Note: Descriptions are shown in the official language in which they were submitted.
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IMPREGNATED GLASS FIBER STRANDS
AND PROiDUCTS INCLUDING THE SAME
Cross Reference to Related Applications
This patent application is a continuation-in-part application of U.S.
Serial No. 09/170,566 of B. Novich et al. entitled "Impregnated Glass
Fiber Strands and Products Including the Same" filed on October 13,
1998, which is a continuation-in-part application of U.S. Serial No.
09/034,077 of B. Novich et al. entitled "Impregnated Glass Fiber Strands
and Products Including the Same" filed March 3, 1998, now abandoned.
This patent application is related to U.S. Patent Application Serial
No. 09/170,579 of B. Novich et al. entitled "Methods for Inhibiting
Abrasive Wear of Glass Fiber Strands" filed on October 13, 1998, which
is a continuation-in-part application of U.S. Application Serial No.
09/034,078 of B. Novich et al. entitled "Methods for Inhibiting Abrasive
Wear of Glass Fiber Strands" filed March 3, i 998, now abandoned; U.S.
Patent Application Serial l~o. 09/170,781 of B. Novich et al. entitled
"Glass Fiber Strands Coated With Thermally Conductive Inorganic Solid
Particles and Products Including the Same" filed on October 13, 1998,
which is a continuation-in-part application of U.S. Application Serial No.
09/034,663 of B. Novich et al. entitled "Glass Fiber Strands Coated With
Thermally Conductive Inorganic Solid Particles and Products Including the
Same" filed March 3, 1988, now abandoned; U.S. Patent Application
Serial No. 09/170,780 of B. Novich et al. entitled "Inorganic Lubricant-
Coated Glass Fiber Strands and Products Including the Same" filed on
October 13, 1998, which is a continuation-in-part application of U.S.
Application Serial No. 09/034,525 of B. Novich et al. entitled "Inorganic
Lubricant-Coated Glass Fiber Strands and Products Including the Same"
filed March 3, 1998, now abandoned; U.S. Patent Application Serial No.
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09/170,565 of B. Novich et al. entitled "Inorganic Particle-Coated Glass
Fiber Strands and Products Including the Same" filed on October 13,
1998, which is a continuation-in-part application of U.S. Application Serial
No. 09/034,056 of B. Newich et al. entitled "Inorganic Particle-Coated
Glass Fiber Strands and Products Including the Same" filed March 3,
1998, now abandoned; II.S. Patent Application Serial No. 09/170,578of
B. Novich et al. entitled "Glass Fiber-Reinforced Laminates, Electronic
Circuit Boards and Methods for Assembling a Fabric" filed October 13,
1998, which is a continuation-in-part application of U.S. Application Serial
No. 09/130,270 of B. Novich et al. entitled "Glass Fiber-Reinforced
Laminates, Electronic Circuit Boards and Methods for Assembling a
Fabric" filed August 6, 1'98, which is a continuation-in-part application of
U.S. Serial No. 09/034,525 of B. Novich et al. entitled "Inorganic
Lubricant-Coated Glass Fiber Strands and Products Including the Same"
filed March 3, 1998, novv abandoned.
This application claims the benefit of U.S. Provisional Application Nos.
60/133,076, filed May 7, 1999, and 60/146,337, filed July 30, 1999.
Field of the Invention
This invention relates generally to coated fiber strands for reinforcing
composites and, more specifically, to glass fiber strands coated with
particles
that provide interstitial spaces between adjacent glass fibers of the strand.
Background of the Invention
In thermosetting melding operations, good "wet-through" (penetration
of a polymeric matrix material through the mat or fabric) and "wet-out"
(penetration of a polymeric matrix material through the individual bundles or
strands of fibers in the mast or fabric) properties are desirable. In
contrast,
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good dispersion properties are of predominant concern in typical
thermoplastic molding operations.
Japanese Patent Application No. 9-208,268 discloses a cloth having
yam formed from glass fibers coated immediately after spinning with starch or
a synthetic resin and 0.001 - 20.0 weight percent of inorganic solid particles
such as colloidal silica, calcium carbonate, kaolin and talc having average
particles sizes of 5 to 2001) nanometers (0.05 to 2 micrometers) to improve
resin impregnation. In paragraph 13 of the Detailed Description of the
Invention, it is disclosed treat such coatings having more than 20 weight
percent inorganic solid particles cannot be applied to the glass fiber. Heat
or
water de-oiling is required prior to formation of a laminate to remove the
coating from the glass fibers.
U.S. Patent No. 3,~~12,569 discloses adhering particles of alumina to
the surfaces of the glass fibers to improve penetration of resin between glass
reinforcement fibers durirn~ formation of a composite. However the Mohs'
hardness values for alumina is greater than about 9', which can cause
abrasion of softer glass fibers.
Soviet Union No. 859400 discloses an impregnating composition for
manufacturing laminates of glass fiber cloth, the composition containing an
alcoholic solution of phenol-formaldehyde resin, graphite, molybdenum
disulphide, polyvinyl butyral and surfactant. Volatile alcoholic solvents are
not
desirable for glass fiber production applications.
Hollow filler particles can be used to modify the impregnation
characteristics of the reinforcing material and/or reduce the overall density
of
the composite material produced therefrom. For example, US. Patent No.
5,412,003 discloses imprE:gnating a glass fiber with a resin co(nposition
containing an unsaturated polyester, a polymerizable monomer, a
' See R. Weast (Ed.), Handbook of Chemistry and Physics, CRC Press (1975) at
page F-22,
which is hereby incorporated by reference.
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thermoplastic resin, a polymerization initiator and hollow glass microspheres
(col. 2, lines 6-14). Molding materials and molded products obtained from the
impregnated fibers are ligr~t in weight (col. 2, lines 26-30). U.S. Patent No.
4,820,575 discloses incorporating hollow body fillers, and particularly heat
expandable hollow body fillers, having particle diameters ranging from about
20 to about 300 micrometers into the interspaces between fibers of
reinforcing materials to permanently reduce the resin pick up and specific
weight of the reinforcing materials (col. 4, lines 39-43 and col. 3, lines 15-
30).
Preferably, the fillers are applied as an aqueous, binder-free suspension to
the reinforcing material (col. 3, lines 63-68 and col. 4, lines 1-3}. U.S.
Patent
No. 5,866,253 discloses incorporating heat expandable hollow particles into
fiber strands. The particles are expandable into "microballoons" to create
fiber strands having enlarc,~ed cross sectional dimensions to be used in
composite materials. The expanded particles generally have particle sizes
ranging from about 40 to ~i0 micrometers which is greater than the diameter
of the fibers of the strand {col. 3, lines 5-10). Fiber strands having the
expanded particles typically have about a four-fold increase in diameter as
compared to fibers without the expanded particles and the density of the
strand is considerably reduced {col. 4, lines 12-18). The larger strand
diameter allows for fewer strands to be used in the formation of composites
thereby providing lower finished product density (col. 1, lines 39-43).
In the case of composites or laminates formed from fiber strands
woven into fabrics, in addition to providing good wet-through and good wet-
out properties of the strands, it is desirable that the coating on the
surfaces of
the fibers strands protect the fibers from abrasion during processing, provide
for good weavability, particularly on air jet looms and be compatible with the
polymeric matrix material into which the fiber strands are incorporated. Many
sizing components commonly used on fiber strands to be woven into fabrics
can adversely affect adhesion between the glass fibers and the laminate
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matrix material. For example, starch, which is a commonly used sizing
component for textile fiber:, is generally not compatible with laminate resin
matrix material. To avoid incompatibility between the glass fibers and the
matrix material, the coatinc,~ or sizing composition is typically removed from
the woven cloth prior to larnination by thermal decomposition of the sizing
components (called heat cleaning or de-oiling) or by washing the cloth with
water (also called de-oiling). A conventional heat cleaning process to
thermally decompose sizing components involves heating the cloth at
380°C
for 60-80 hours. The heat cleaned cloth is then re-coated with a silane
coupling agent to improve adhesion between the glass fiber strands and the
matrix material. However, such de-oiling processes are not always
completely successful in rE;moving the incompatible materials and can further
contaminate the fabric with products of decomposition.
Japanese Patent Application 8-119-682 discloses a primary sizing
composition containing a vuater-soluble epoxy resin that can be easily
removed by rinsing with w~~ter {page 3, paragraph 2) to improve the removal
or de-oiling characteristics of sizing compositions for use in composites.
Preferably, the primary sizing comprises an epoxy resin having aggregated
and formed particles with diameters of 0.5 to 50 micrometers and a pH
between 5.5 and 7.5 (pagE: 4, paragraph 1). Preferably, the epoxy resin is
colloid with particles of 1 to 5 micrometers (page 6, paragraph 1 ). The
particles are believed to bc: beneficial in preventing the flow or migration
of
the epoxy resin during dryiing.
U.S. Patent No. 4,009,317 discloses a primary sizing composition
containing emulsified clad particles that produce a film on glass fibers and
have good burn off characteristics {col. 1. lines 67-68 and col. 2, lines 1-
3).
Other patents disclose methods of forming composite material by
incorporating particles of polymeric resins into fiber strands and
subsequently
heating or pressing the strands to form a composite. U.S. Patent No.
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4,615,933 discloses saturating glass fabrics or strands with aqueous
dispersions of polytetrafluoroethylene or other fluoro-polymer particles to
form
strands having about 50 to 70 percent by weight fiber and about 30 to 50
percent by weight polytetrafluoroethylene. The strands are subsequently
pressed to form composites. U.S. Patent Nos. 5,364,657 and 5,370,911
disclose incorporating polymeric particles into fiber strands by either
contacting a moistened strand with a dry polymer particle-laden air stream
(col. 2, lines 60-68 and col. 3 lines 1-8 of Patent 5,364,fi57) or
electrostatically
adhering polymer particles to a fiber strand (col. 3, lines 13-37 of Patent
5,370,911). The fiber strands are then heated to coalesce the particles into
continuous polymeric coatiing that comprises greater than about 10 percent by
weight of the coated fiber :strand. Other additives such as binders and
emulsifiers agents are generally not desirable in the coatings {col. 4, lines
50-
51 of Patent 5,370,911 arn~ col. 2, lines 18-21 of Patent 5,364,657).
However, coated fiber strands having high levels of polymeric coatings on
their surfaces are often difficult to weave on air jet looms.
There is a need for coatings that inhibit abrasion and breakage of glass
fibers, are compatible with a wide variety of polymeric matrix materials and
provide for good wet-out and wet-through by the matrix material. In addition,
it would be particularly advantageous if the coatings were compatible with
modern air jet weaving equipment to increase productivity.
aummaryr of the Invention
One aspect of the present invention is a coated fiber strand
comprising at least one fiiber having a layer of a dried residue of a resin
compatible coating composition on at least a portion of a surface of the at
least one fiber, the resin compatible coating composition comprising: (a) a
plurality of discrete, dimE;nsionally stable particles formed from materials
selected from the group consisting of organic materials, polymeric
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materials, composite materials and mixtures thereof that provide an
interstitial space between the at least one fiber and at least one adjacent
fiber, the particles havinc,~ an average particle size of about 0.1 to about 5
micrometers; (b) at least one lubricious material; (c) at least one polymeric
film former; and (d) at le~ast one coupling agent, and a fabric incorporating
at least one of the fiber strands.
Another aspect the present invention is a coated fiber strand
comprising at least one glass fiber having a dried residue of an aqueous
resin compatible coating composition on at least a portion of a surface of
the at least one fiber, thES aqueous resin compatible coating composition
comprising (a) a plurality of discrete, polymeric organic particles that
provide an interstitial space between the at least one glass fiber and at
least one adjacent glass fiber, the particles having an average particle size
of up to about 5 micrometers, (b) a lubricious material selected from the
group consisting of oils, waxes, greases and mixtures thereof, (c)
polymeric film-forming material selected from the group consisting of
thermosetting polymeric materials, thermoplastic polymeric materials,
natural polymeric materi~~ls and mixtures thereof, and (d) a coupling agent,
and a fabric incorporating at least one of the fiber strands.
Still another aspeca of the present invention is a coated fiber strand
comprising at least one c,~lass fiber having a dried residue of an aqueous
resin compatible coating composition on at least a portion of a surface of
the at least one fiber, the aqueous resin compatible coating composition
comprising: (a) a plurality of particles comprising; (i) at least one particle
formed from an acrylic copolymer which is a copolymer of styrene and
acrylic; and (ii) at least one particle formed from an inorganic solid
lubricant material selected from the group consisting of boron nitride,
graphite and metal dichalcogenides, wherein the particles have an average
particle size of up to about 5 micrometers and comprise about 35 to about
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55 weight percent of the resin compatible coating composition on a total
solids basis; (b) a lubricious material selected from the group consisting of
cetyl palmitate, cetyl laurate, octadecyl laurate, octadecyl myristate,
octadecyl palmitate, octadecyl stearate and paraffin, wherein the
lubricious material comprises from about 20 to about 40 weight percent
of the resin compatible coating composition on a total solids basis;
(c) thermoplastic polymeric film forming material selected from the group
consisting of polyvinyl pyrrolidone, polyvinyl alcohol, polyacrylamide,
polyacryfic acid and copolymers and mixtures thereof, wherein the
thermoplastic polymeric film-forming material comprises about 5 to about
30 weight percent of the. resin compatible coating composition on a total
solids basis; and (d) a coupling agent, and a fabric incorporating at least
one of the fiber strands.
Yet another aspect of the present invention is a fabric comprising a
plurality of fibers strands comprising at least one fiber, at least a portion
of the fabric having a re:~idue of a resin compatible coating composition
comprising: (a) a pluralit~i of discrete, dimensionally stable particles
formed from materials selected from the group consisting of organic
materials, polymeric materials, composite materials and mixtures thereof
that provide an interstitial space between the at least one fiber and at
least one adjacent fiber, the particles having an average particle size of
about 0.1 to about 5 mic;rorneters; (b) at least one lubricious material;
(c) at least one polymeric film former; and (d) at least one coupling agent.
Briefi Description of the Drawings
The foregoing summary, as well as the following detailed description of
the preferred embodiments, will be better understood when read in
conjunction with the appended drawings. In the drawings:
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Fig. 1 is a perspective view of a coated fiber strand having a primary
layer of a dried residue of a coating composition according to the present
invention;
Fig. 2 is a perspective view of a coated fiber strand having a primary
layer of a dried residue of a sizing composition and thereupon a secondary
layer of a secondary coating composition according to the present invention;
Fig. 3 is a perspective view of a coated fiber strand having a primary
layer of a dried residue of a sizing composition, a secondary layer of a
secondary coating composition, and a tertiary layer thereupon according to
the present invention;
Fig. 4 is a top plan view of a composite according to the present
invention;
Fig. 5 is a top plan view of a fabric according to the present invention;
Fig. 6 is a cross-sectional view of an electronic support according to
the present invention; and
Figs. 7 and 8 are cross-sectional views of alternate embodiments of an
electronic support according to the present invention.
Detailed Description of the Invention
The fiber strands of the present invention have a unique coating that
not only inhibits abrasion and breakage of the fibers during processing but
also provides good wet-through, wet-out and dispersion properties in
formation of composites. Good laminate strength, good thermal stability,
good hydrolytic stability, low corrosion and reactivity in the presence of
high
humidity, reactive acids and alkalies and compatibility with a variety of
polymeric matrix materials, which can eliminate the need for removing the
coating, and in particular heat cleaning, prior to lamination, are other
desirable characteristics which are exhibited by the coated fiber strands of
the
present invention.
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Another significant .advantage of the coated fiber strands of the present
invention is good processability in weaving and knitting. Low fuzz and halos,
low broken filaments, low ;strand tension, high fliability and low insertion
time
are characteristics provided by the coated glass fiber strands of the present
invention that facilitate we~~ving and knitting and consistently provide a
fabric
with few surface defects for printed circuit board applications.
Significant advantal~es of composite materials made from the fiber
strands of the present invention include good flexural strength, good
interlaminar bond strength and good hydrolytic stability, i.e. resistance to
migration of water along tree fiber/matrix interface. Additionally, electronic
supports and printed circuiit boards made from the fiber strands in accordance
with the present invention have good drillability and resistance to metal
migration (also referred to as cathodic-anodic filament formation or CAF}. In
particular, printed circuit beards made from the fiber strand in accordance
with the present invention have low tool wear during drilling and good
locational accuracy of drill~sd holes.
Referring now to F'u,~. 1, wherein like numerals indicate like elements
throughout, there is shown in Fig. 1 a coated fiber strand 10 comprising a
plurality of fibers 12, according to the present invention. As used herein,
"strand" means a plurality of individual fibers. The term "fiber" means an
individual filament. Although not limiting in the present invention, the
fibers 12
typically have an average nominal fiber diameter ranging from about 3 to
about 35 micrometers. Preferably the average nominal fiber diameter of the
present invention is about 5 micrometers and greater. For "fine yarn"
applications, the averagenominal fiber diameter preferably ranges from about
5 to about 7 micrometers.
The fibers 12 can be formed from any type of fiberizable material
known to those skilled in the art including fiberizable inorganic materials,
fiberizable organic materials and mixtures and combinations thereof. The
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inorganic and organic materials can be either man-made or naturally
occurring materials. One skilled in the art will appreciate that the
fiberizable
inorganic and organic materials can also be polymeric materials. As used
herein the term "polymeric material" means a material formed from
macromolecules composed of long chains of atoms that are linked together
and that can become entangled in solution or in the solid state2. As used
herein, the term "fiberizable" means a material capable of being formed into a
generally continuous filament, fiber, strand or yarn.
Preferably, the fibers 12 are formed from an inorganic, fiberizable
glass material. Fiberizable glass materials useful in the present invention
include but are not limited to those prepared from fiberizable glass
compositions such as "E-c,~lass", "A-glass", "C-glass", "D-glass", "R-glass",
"S-glass", and E-glass deirivatives. As used herein, "E-glass derivatives"
means glass compositions that include minor amounts of fluorine and/or
boron and preferably are lluorine-free and/or boron-free. Furthermore, as
used herein, minor mean:. less than about 1 weight percent fluorine and less
than about 5 weight percent boron. Basalt and mineral wool are examples of
other fiberizable glass materials useful in the present invention. Preferred
glass fibers are formed from E-glass or E-glass derivatives. Such
compositions are well known to those skilled in the art and further discussion
thereof is not believed to Ibe necessary in view of the present disclosure.
The
glass fibers of the presen~r invention can be formed in any suitable method
known in the art, for forming glass fibers. For example, glass fibers can be
formed in a direct-melt fiber forming operation or in an indirect, or marble-
melt, fiber forming operation. In a direct-melt fiber forming operation, raw
materials are combined, rnelted and homogenized in a glass ri~elting furnace.
The molten glass moves lFrom the furnace to a forehearth and into fiber
2 James Mark et al. Inorganic f'olvmers, Prentice Hall Polymer Science and
Engineering
Series, {1992) at page 1 which is hereby incorporated by reference.
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forming apparatuses where the molten glass is attenuated into continuous
glass fibers. In a marble-smelt glass forming operation, pieces or marbles of
glass having the final desired glass composition are preformed and fed into a
bushing where they are melted and attenuated into continuous glass fibers. If
a premelter is used, the marbles are fed first into the premelter, melted, and
then the melted glass is fE:d into a fiber forming apparatus where the glass
is
attenuated to form continuous fibers. In the present invention, the glass
fibers are preferably formed by the direct-melt fiber forming operation. For
additional information elating to glass compositions and methods of forming
the glass fibers, see K. Loewenstein, The Manufacturing Technology of Glass
Fibres, (3d Ed. 1993) at pages 30-44, 47-103, and 115-165, U.S. Patents
4,542,106 and 5,789,329, and IPC-EG-140 "Specification for Finished Fabric
Woven from 'E' Glass for Printed Boards" at page 1, a publication of The
Institute for Interconnecting and Packaging Electronic Circuits (June 1997),
which are hereby incorporated by reference.
Non-limiting examples of suitable non-glass fiberizable inorganic
materials include ceramic. materials formed from silicon carbide, carbon,
graphite, mullite, aluminum oxide and piezoelectric ceramic materials. Non-
limiting examples of suitable fiberizable organic materials include cotton,
cellulose, natural rubber, flax, ramie, hemp, sisal and wool. Non-limiting
examples of suitable fiberizable organic polymeric materials include those
formed from polyamides i;such as nylon and aramids), thermoplastic
polyesters (such as polyeahylene terephthalate and polybutylene
terephthalate), acrylics (such as pofyacrylonitriles), polyolefins,
polyurethanes
and vinyl polymers (such as polyvinyl alcohol). Non-glass fiberizable material
useful in the present invention and methods for preparing and processing
such fibers are discussed at length in the Encyclopedia of Polymer Science
and Technoloav, Vol. 6 ('1967) at pages 505-712, which is hereby
incorporated by referencES. It is understood that blends or copolymers of any
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of the above materials and combinations of fibers formed from any of the
above materials can be used in the present invention, if desired.
The present invention will now be discussed generally in the context of
glass fiber strands, although one skilled in the art would understand that the
strand 10 can comprise fivers 12 formed from any fiberizable material known
in the art as discussed above.
With continued reference to Fig. 1, in a preferred embodiment, at least
one and preferably all of the fibers 12 of fiber strand 10 of the present
invention have a layer 14 ~of a residue of a coating composition on at least a
portion 17 of the surfaces 16 of the fibers 12 to protect the fiber surfaces
16
from abrasion during processing and inhibit fiber breakage. Preferably, the
layer 14 is present on the entire outer surface 16 or periphery of the fibers
12.
The coating compositions of the present invention are preferably
aqueous coating compositions and more preferably aqueous, resin
compatible coating compositions. Although not preferred for safety reasons,
the coating compositions ~;an contain volatile organic solvents such as
alcohol
or acetone as needed, burr preferably are free of such solvents. Additionally,
the coating compositions of the present invention can be used as primary
sizing compositions and/or secondary sizing or coating compositions.
As used herein, in ~~ preferred embodiment the terms "size", "sized" or
"sizing" refer to a coating composition applied to the fibers. The terms
"primary size" or "primary aizing" refer to the coating composition applied to
the fibers immediately after formation of the fibers. The terms "secondary
size", "secondary sizing" or "secondary coating" mean coating compositions
applied to the fibers after i:he application of a primary size. This coating
can
be applied to the fiber before the fiber is incorporated into a fabric or it
can be
applied to the fiber after the fiber is incorporated into a fabric , e.g. by
coating
the fabric. In an alternative embodiment, the terms "size", "sized" or
"sizing"
additionally refer to a coating composition (also known as a "finishing size")
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applied to the fibers after at least a portion, and typically all of a
conventional,
non-resin compatible sizing composition has been removed by heat or
chemical treatment, i.e., the finishing size is applied to bare glass fibers
incorporated into a fabric form.
As used herein, the term "resin compatible" means the coating
composition applied to the glass fibers is compatible with the polymeric
matrix
material into which the glass fibers will be incorporated such that the
coating
composition (or selected coating components) does not require removal prior
to incorporation into the matrix material (such as by heat cleaning),
facilitates
good wet-out and wet-through of the matrix material during processing and
results in composite materials having desired physical properties and
hydrolytic stability.
The coating composition of the present invention comprises one or
more, and preferably a plurality of particles 18 that when applied to at least
one fiber 23 of the plurality of fibers 12 adheres to the outer surface 16 of
the
at least one fiber 23 and provides one or more interstitial spaces 21 between
adjacent glass fibers 23, 2;i of the strand 10. These interstitial spaces 21
correspond generally to the: average size 19 of the particles 18 positioned
between the adjacent fibers.
The particles 18 of the present invention are preferably discrete
particles. As used herein tine term "discreten means that the particles do not
tend to coalesce or combine to form films under processing conditions, but
instead generally retained i:heir individual shape or form. In addition, the
particles are preferably dimensionally stable. As used herein the term
"dimensionally stable particles" means that the particles will generally
maintain their average particle size and shape under processing conditions,
such as the forces generated between adjacent fibers during weaving, roving
and other processing operations, so as to maintain the desired interstitial
spaces between adjacent fibers 23, 25. In other words, the particles
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preferably will not crumble, dissolve or substantially deform in the coating
composition to form a partiicle having a maximum dimension less than its
selected average particle size under typical glass fiber processing
conditions,
such as exposure to tempE~ratures of up to about 25°C and preferably up
to
about 100°C, and more prE:ferably up to about 140°C.
Additionally, the
particles 18 should not substantially enlarge or expand in size under glass
fiber processing conditions and, more particularly, under composite
processing conditions where the processing temperatures can exceed
150°C.
As used herein, the phrase' "should not substantially enlarge in size" in
reference to the particles means that the particles should not expand or
increase in size to more than approximately 3 times their initial size during
processing. Preferably, the coating compositions of the present invention are
essentially free of heat expandable hollow particles. As used herein, the term
"heat expandable hollow particles" means hollow particles filled with or
containing a blowing agent, which when exposed to temperatures sufficient to
volatilize the blowing agent expand or substantially enlarge in size. As used
herein the term "essentially free of means the sizing composition comprises
less than about 20 weight percent of heat expandable hollow particles on a
total solids basis, more preferably less than about 5 weight percent, and most
preferably less than 0.001 weight percent. Furthermore, as used herein, the
term "dimensionally stable" includes both crystalline and non-crystalline
materials.
In addition, although not required, it is preferred that the particles 18
are non-waxy. The term "non-waxy" means the materials from which the
particles are formed are not wax-like. As used herein, the term "wax-like"
means materials composer primarily of unentangled hydrocarbons chains
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having an average carbon chain length ranging from about 25 to about 100
carbon atoms3~''.
Preferably, the particles 18 in the present invention are discrete,
dimensionally stable, non-waxy particles.
The particles 18 can have any shape or configuration desired.
Although not limiting in the present invention, examples of suitable particle
shapes include spherical (:such as beads, microbeads or hollow spheres),
cubic, platy or acicular (elongated or fibrous). Additionally, the particles
18
can have an internal structure that is hollow, porous or void free, or a
combination thereof. In adldition, the particles 18 can have a combination of
these structures, e.g. a hollow center with porous or solid walls. For more
information on suitable particle characteristics see H. Katz et al. (Ed.),
Handbook of Fillers and Plastics, (1987) at pages 9-10 which are hereby
incorporated by reference.
The particles 18 can be formed from materials selected from the group
consisting of polymeric anti non-polymeric inorganic materials, polymeric and
non-polymeric organic materials, composite materials and mixtures thereof.
As used herein the term "polymeric inorganic material" means a polymeric
material having a backbone repeat unit based on an element or elements
other than carbon. For mare information see J. E. Mark et al. at page 5,
which is hereby incorporated by reference. Polymeric organic materials
include synthetic polymeric: materials, semisynthetic polymeric materials and
natural polymeric materials. An "organic material", as used herein, means all
compounds of carbon excf:pt such binary compounds as the carbon oxides,
the carbides, carbon disulfide, etc.; such ternary compounds as the metallic
cyanides, metallic carbonyls, phosgene, carbonyl sulfide, etc.; and metallic
3 L. H. Sperling Introduction of P-hysical Polymer Science, John Wiley and
Sons, Inc. (198fi) at
pages 2-5, which are hereby incorporated by reference.
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-17-
carbonates, such as calcium carbonate and sodium carbonate. See R.
Lewis, Sr., Hawley's Condensed Chemical Dictionary, (12th Ed. 1993) at
pages 761-762 which are hereby incorporated by reference. More generally,
organic materials include carbon containing compounds wherein the carbon is
typically bonded to itself and to hydrogen, and often to other elements as
well
and excludes carbon-containing ionic compounds. See M. Silberberg,
Chemistry The Molecular Nature of Matter and Change, {1996) at page 586,
which is hereby incorporated by reference. The term " inorganic material"
generally means all materials that are not compounds of carbon with the
exception of carbon oxides, and carbon disulfide. See R. Lewis, Sr., Hawley's
Condensed Chemical Dictionary, (12th Ed. 1993} at page 636 which are
hereby incorporated by reference. As used herein the term "inorganic
materials" means any matE~rial that is not an organic material. As used here
in the term "composite material" means a combination of two or more different
materials. For more information on particles useful in the present invention,
see G. Vllypych, Handbook of Fillers, 2nd Ed. (1999) at pages 15-202, which
are hereby incorporated by reference.
Non-polymeric, inorc,~anic materials useful in forming the particles 18 of
the present invention inclucte inorganic materials selected from the group
consisting of metals, oxides, carbides, nitrides, borides, sulfides,
silicates,
carbonates, sulfates and hydroxides. A non-limiting example of a suitable
inorganic nitride from which the particles 18 are formed is boron nitride,
which
is the preferred inorganic material from which particles 18 useful in the
present invention are formE:d. A non-limiting example of a useful inorganic
oxide is zinc oxide. Suitable inorganic sulfides include molybdenum disulfide,
tantalum disulfide, tungsten disulfide and zinc sulfide. Useful inorganic
silicates include aluminum silicates and magnesium silicates, such as
' W. Pushaw, et al. "Use of Micronised Waxes and Wax Dispersions in Waterborne
Systems"
Polymers. Paint Colours Journal, V.189, No. 4412 January 1999 at pages 18-21
which are
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-18-
vermiculite. Suitable metals include molybdenum, platinum, palladium, nickel,
aluminum, copper, gold, iron, silver and alloys and mixtures thereof.
Although not required, the particles 18 are formed from solid lubricant
materials. As used herein the term "solid lubricant" means any solid used
between two surfaces to pn~ovide protection from damage during relative
movement and/or to reduce friction and wear. In one embodiment, the solid
lubricants are inorganic sollid lubricants. As used herein, "inorganic solid
lubricant" means that the solid lubricants have a characteristic crystalline
habit which causes them to shear into thin, flat plates which readily slide
over
one another and thus produce an antifriction lubricating effect between the
glass fiber surface and an .adjacent solid surface, at least one of which is
in
motion. See R. Lewis, Sr., Hawley's Condensed Chemical Dictionar~r, (12th
Ed. 1993) at page 712, which is hereby incorporated by reference. Friction is
the resistance to sliding one solid over another. F. Clauss, Solid Lubricants
and Self Lubricating Solids,, (1972) at page 1, which is hereby incorporated
by
reference.
In one embodiment of the present invention, the solid lubricant
materials have a lamellar structure. Solid lubricants having a lamellar
structure are composed of sheets or plates of atoms in hexagonal array, with
strong bonding within the sheet and weak van der Waals bonding between
sheets, providing low shear strength between sheets. A non-limiting example
of a lamellar structure is a (hexagonal crystal structure. K. Ludema Friction.
Wear. Lubrication (1996)at page 125, Solid Lubricants and Self Lubricating
Solids at pages 19-22, 42-;54, 75-77, 80-81, 82, 90-102, 113-120 and 128,
and W. Campbell "Solid Lubricants", Boundar)i Lubrication' An Appraisal of
World Literature, ASME REaearch Committee on Lubrication (1969) at pages
202-203, which are hereby incorporated by reference. Inorganic solid
hereby incorporated by reference.
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particles having a lamellar fullerene structure are also useful in the present
invention.
Non-limiting examK>les of suitable inorganic solid lubricant materials
having a lamellar structure that are useful in forming the particles 18 of the
present invention include boron nitride, graphite, metal dichalcogenides,
mica,
talc, gypsum, kaolinite, caiicite, cadmium iodide, silver sulfide and mixtures
thereof. Preferred inorganic solid lubricant materials include boron nitride,
graphite, metal dichalcogE:nides and mixtures thereof. Suitable metal
dichalcogenides include molybdenum disulfide, molybdenum diselenide,
tantalum disulfide, tantalum diselenide, tungsten disulfide, tungsten
diseienide
and mixtures thereof.
A non-limiting exannple of an inorganic solid lubricant material for use
in the coating composition of the present invention having a hexagonal crystal
structure is boron nitride. Particles formed from boron nitride, zinc sulfide
and
montmorillonite also provide good whiteness in composites with polymeric
matrix materials such as nylon 6,6.
Non-limiting exam~~les of particles formed from boron nitride that are
suitable for use in the preaent invention are PolarTherm~ 100 Series (PT
120, PT 140, PT 160 and PT 180), 300 Series (PT 350) and 600 Series (PT
620, PT 630, PT 640 and PT 670) boron nitride powder particles which are
commercially available from Advanced Ceramics Corporation of Lakewood,
Ohio. "PolarTherm~ Thermally Conductive Fillers for Polymeric Materials" a
technical bulletin of Advanced Ceramics Corporation of Lakewood, Ohio
(1996), which is hereby incorporated by reference. These pa .rticles have a
thermal conductivity of about 250-300 Watts per meter °K at
25°C, a dielectric
constant of about 3.9 and a volume resistivity of about 10'5 olim-centimeters.
The 100 Series powder particles have an average particle size ranging from
about 5 to about 14 micrometers, the 300 Series powder particles have an
average particle size rangiing from about 100 to about 150 micrometers and
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the 600 Series powder particles have an average particle size ranging from
about 16 to greater than about 200 micrometers.
In another embodiment of the present invention, the particles 18 are
formed from inorganic solid lubricant materials that are non-hydratable. As
used herein, "non-hydratable" means that the solid inorganic lubricant
particles do not react with molecules of water to form hydrates and contain
water of hydration or water of crystallization. A "hydrate" is produced by the
reaction of molecules of water with a substance in which the H-OH bond is
not split. See R. t_ewis, Sr., Hawlev's Condensed Chemical DictionarX, (12th
Ed. 1993) at pages 609-610 and T. Perros, Chemistry, (1967) at pages 186-
187, which are hereby incorporated by reference. Hydrates contain
coordinated water, which coordinates the cations in the hydrated material and
cannot be removed without the breakdown of the structure, and/or structural
water, which occupies interstices in the structure to add to the electrostatic
energy without upsetting the balance of charge. R. Evans, An Introduction to
Crystal Chemistry, (1948) .at page 276, which is hereby incorporated by
reference. Preferably, the coating composition is essentially free of
hydratable inorganic solid !lubricants. As used herein the term "essentially
free of means the coating composition comprises less than about 20 weight
percent of hydratable inorganic lubricant particles on a total solids basis,
more
preferably less than about 5 weight percent, and most preferably less than
0.001 weight percent.
While not preferred, the coating compositions according to the present
invention can contain particles formed from hydratable or hydrated inorganic
solid lubricant materials in addition to the non-hydratable inorganic solid
lubricant materials discussed above. Non-limiting examples of such
hydratable inorganic solid (lubricant materials are clay mineral
phyilosilicates,
including micas (such as muscovite), talc, montmorillonite, kaolinite and
gypsum.
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The particles 18 ca n be formed from non-polymeric, organic materials.
Examples of non-polymeric, organic materials useful in the present invention
include but are not limited to stearates (such as zinc stearate and aluminum
stearate), carbon black and stearamide.
The particles 18 cain be formed from inorganic polymeric materials.
Non-limiting examples of useful inorganic polymeric materials include
polyphosphazenes, polysillanes, polysiloxane, polygeremanes, polymeric
sulfur, polymeric selenium, silicones and mixtures thereof. A specific, non-
limiting example of a particle formed from an inorganic polymeric material
suitable for use in the present invention is Tospearl5, which is a particle
formed from cross-linked s~iloxanes and is commercially available from
Toshiba Silicones Company, Ltd. of Japan.
Suitable synthetic, organic polymeric materials from which the particles
can be formed include, but are not limited to, thermosetting materials and
thermoplastic materials. ~~uitable thermosetting materials include
thermosetting polyesters, vinyl esters, epoxy materials, phenolics,
aminoplasts, thermosettinca polyurethanes and mixtures thereof. A specific,
non-limiting example of a preferred synthetic polymeric particle formed from
an epoxy material is an epoxy microgel particle.
Suitable thermopla:>tic materials include thermoplastic polyesters,
polycarbonates, polyolefins, acrylic polymers, polyamides, thermoplastic
polyurethanes, vinyl polymers and mixtures thereof. Preferred thermoplastic
polyesters include but are not limited to polyethylene terephthalate,
polybutylene terephthalate~ and polyethylene naphthalate. Preferred
polyolefins include but are not limited to polyethylene, polypropylene and
poiyisobutene. Preferred sacrylic polymers include copolymers of styrene and
acrylic and polymers containing methacrylate. Non-limiting examples of
5 See R. J. Perry "Applications for Cross-Linked Siloxane Particles" Chemtech.
February 1999
at pages 39-44.
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synthetic polymeric particles formed from an acrylic copolymer are
ROPAQUE~ HP-10558, which is an opaque, non-film-forming, styrene acrylic
polymeric synthetic pigmeint having a 1.0 micrometer particle size, a solids
content of 26.5 percent by weight and a 55 percent void volume, ROPAQUE~
OP-96', which is an opaque, non-film-forming, styrene acrylic polymeric
synthetic pigment dispersion having a particle size of 0.55 micrometers and a
solids content of 30.5 percent by weight, and ROPAQUE~ OP-62 l_Oe which
is also an opaque, non-film-forming, styrene acrylic polymeric synthetic
pigment dispersion having a particles size of 0.40 micrometers and a solids
content of about 36.5 percent by weight, each of which are commercially
available from Rohm and Haas Company of Philadelphia, PA.
Suitable semisynthe;tic, organic polymeric materials from which the
particles 18 can be formed) include but are not limited to cellulosics, such
as
methylcellulose and cellulose acetate; and modified starches, such as starch
acetate and starch hydrox,~ethyl ethers.
Suitable natural pohymeric materials from which the particles 18 can be
formed include but are not limited to polysaccharides, such as starch;
polypeptides, such as casein; and natural hydrocarbons, such as natural
rubber and gutta percha.
In one embodiment of the present invention, the polymeric particles 18
are formed from hydrophobic polymeric materials to reduce or limit moisture
absorption by the coated strand. Non-limiting examples of hydrophobic
polymeric materials believE:d to be useful in the present invention include
but
are not limited to polyethylene, polypropylene, polystyrene and
s See product property sheet entitled: "ROPAQUE~ HP-1055, Hollow Sphere
Pigment for
Paper and Paperboard Coatings." October 1994, available from Rohm and Haas
Company,
Philadelphia, PA at page 1 which is hereby incorporated by reference.
' See product technical bulletin entitled: "Architectural Coatings- ROPAQUE~
OP-96, The All
Purpose Pigment", April 1997 available from Rohm and Haas Company,
Philadelphia, PA at
page 1 which is hereby incorporated by reference.
a Ibid.
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polymethylmethacrylate. Jon-limiting examples of polystyrene copolymers
include ROPAQUE~ HP-1055, ROPAQUE~ OP-96, and ROPAQUE~ OP-62
LO pigments (each discussed above).
In another embodiment of the present invention, polymeric particles 18
are formed from polymeric materials having a glass transition temperature
(Tg) and/or melting point greater than about 25°C and preferably
greater than
about 50°C.
Composite particles 18 useful in the present invention include particles
formed by cladding, encapsulating or coating particles formed from a primary
material with one or more secondary materials. For example, an inorganic
particle formed from an inorganic material such as silicon carbide or
aluminum nitride can be provided with a silica, carbonate or nanoclay coating
to form a useful composite particle. In another example, a silane coupling
agent with alkyl side chains can be reacted with the surtace of an inorganic
particle formed from an inorganic oxide to provide a useful composite particle
.
having a "softer" surface. Other examples include cladding, encapsulating or
coating particles formed from organic or polymeric materials with inorganic
materials or different organic or polymeric materials. A specific non-limiting
example of such compositE: particles is DUALITE, which is a synthetic
polymeric particle coated with calcium carbonate that is commercially
available from Pierce and ;3evens Corporation of Buffalo, NY.
In still another embodiment of the present invention, the particles 18
can be hollow particles formed from materials selected from the group
consisting of inorganic materials, organic materials, polymeric,materials,
composite materials and mixtures thereof. Non-limiting examples of suitable
materials from which the hollow particles can be formed are described above.
Non-limiting examples of a hollow polymeric particle useful in present
invention are ROPAQUE~ HP-1055, ROPAQUE~ OP-96 and ROPAQUE~
OP-62 LO pigments (each discussed above). For other non-limiting
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examples of hollow partic4es that can be useful in the present invention see
H.
Katz et al. (Ed.) (1987) at pages 437-452 which are hereby incorporated by
reference.
The particles 18 can be present in a dispersion, suspension or
emulsion in water. Other :solvents, such as mineral oil or alcohol (preferably
less than about 5 weight percent), can be included in the dispersion,
suspension or emulsion, if' desired. A non-limiting example of a preferred
dispersion of particles formed from an inorganic material is ORPAC BORON
NITRIDE RELEASECOAT~-CONC, which is a dispersion of about 25 weight
percent boron nitride particles in water and is commercially available from
ZYP Coatings, Inc. of Oak Ridge, Tennessee. "ORPAC BORON NITRIDE
RELEASECOAT-CONC", a technical bulletin of ZYP Coatings, Inc., is hereby
incorporated by reference, The boron nitride particles in this product have an
average particle size of less than about 3 micrometers and include about 1
percent of magnesium-aluminum silicate to bind the boron nitride particles to
the substrate to which the dispersion is applied. Other useful products which
are commercially available; from ZYP Coatings include BORON NITRIDE
LUBRICOAT~ paint, and (BRAZE STOP and WELD RELEASE products.
Specific, non-limiting examples of emulsions and dispersions of synthetic
polymeric particles formed from acrylic polymers and copolymers include:
Rhoplex~ GL-623s which is an all acrylic firm polymer emulsion having a
solids content of 45 percent by weight and a glass transition temperature of
about 98°C; EMULSION E. 2321'° which is a hard, methacrylate
polymer
emulsion having a solids content of 45 percent by weight and a glass
transition temperature of about 105°C; ROPAQUE~ OP-96 (discussed
9 See product property sheet entitled: "Rhoplex~ GL-623, Self-Crosslinking
Acrylic Binder of
Industrial Nonwovens", March 1997 available from Rohm and Haas Company,
Philadelphia,
PA which is hereby incorporated by reference.
'° See product property sheet entitled: "Building Products Industrial
Coatings- Emulsion E-
2321 ", 1990, available from Rohm and Haas Company, Philadelphia, PA which is
hereby
incorporated by reference.
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above), which is supplied .as a dispersion having a particle size of 0.55
micrometers and a solids content of 30.5 percent by weight; ROPAQUE~
OP-62 LO (discussed above), which is also a opaque, non-film-forming
synthetic pigment dispersion having a particles size of 0.40 micrometers and
a solids content of about 3~6.5 percent by weight; and ROPAQUE~ HP-1055
(discussed above), which His supplied as a dispersion having a solids content
of about 26.5 percent by weight; all of which are commercially available from
Rohm and Haas Company of Philadelphia, PA.
The particles 18 are' selected to have a average particle size 19
sufficient to effect the desired spacing between adjacent fibers. For example,
the average size 19 of the particles 18 incorporated into a sizing composition
applied to fibers 12 to be processed on air jet looms is preferably selected
to
provide sufficient spacing between adjacent fibers to permit air jet transport
of
the fiber strand 10 across 'the loom. As used herein, "air jet loom" means a
type of loom in which the fill yarn (weft) is inserted into the warp shed by a
blast of compressed air from one or more air jet nozzles. In another example,
the average size 19 of the particles 18 incorporated into a sizing composition
applied to fibers 12 to be impregnated with a polymeric matrix material is
selected to provide sufficient spacing between adjacent fibers to permit good
wet-out and wet-through of the fiber strand 10.
In a specific, non-linniting embodiment of the present invention, the
average particle size 19 of the particles 18 is at least about 0.1
micrometers,
preferably at least about 0..5 micrometers, and ranges from about 0.1
micrometers to about 5 micrometers and preferably from about 0.5
micrometers to about 2.0 rnicrometers. In this embodiment, the particles 18
have an average particle sizes 19 that.is generally smaller than the average
diameter of the fibers 12 to which the coating composition is applied. It has
been observed that twisted yarns made from fiber strands 10 having a layer
14 of a residue of a primary sizing composition comprising particles 18 having
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average particles sizes 19 discussed above can provide sufficient spacing
between adjacent fibers 23, 25 to permit air jet weavability (i.e. air jet
transport across the loom) while maintaining the integrity of the fiber strand
10
and providing acceptable "wet-through" and "wet-outs characteristics when
impregnated with a polymeric matrix material.
In another specific, non-limiting embodiment of the present invention
the average particles size 19 of particles 18 is at least 3 micrometers,
preferably at least about 5 micrometers, and ranges from 3 to about 1000
micrometers, preferably about 5 to about 1000 micrometers, and more
preferably about 10 to about 25 micrometers. Preferably, each of the
particles 18 has a minimurn particle size of at least 3 micrometers, and
preferably of at least about 5 micrometers. It is also preferred in this
embodiment that the average particle size 19 of the particles 18 corresponds
generally to the average nominal diameter of the glass fibers. It has been
observed that fabrics made with strands coated with the particles of the sizes
as discussed above exhibit good "wet-through" and "wet-out" characteristics
when impregnated with a polymeric matrix material.
It will be recognized by one skilled in the art that mixtures of one or
more particles 18 having different average particle sizes 19 can be
incorporated into the sizinc,~ composition in accordance with the present
invention to impart the desired properties and processing characteristics to
the fiber strands 10 and to the products subsequently made therefrom. More
specifically, different sized particles can be combined in required amounts so
as provide fibers having good air jet transport properties as well a fabric
exhibiting good wet-out and wet-through characteristics.
Glass fibers are suk>ject to abrasive wear by contact with asperities of
adjacent glass fibers and/or other solid objects or materials which the glass
fibers contact during forming and subsequent processing, such as weaving or
roving. "Abrasive wear", as used herein, means scraping or cutting off of bits
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of the glass fiber surface sir breakage of glass fibers by frictional contact
with
particles, edges or entities of materials which are hard enough to produce
damage to the glass fiber:~. See K. Ludema at page 129, which is hereby
incorporated by reference. Abrasive wear of glass fiber strands causes
strand breakage during processing and surface defects in products such as
woven cloth and composites, which increases waste and manufacturing cost.
To minimize abrasive wear, in one embodiment of the present
invention, the particles 18 have a hardness value which does not exceed, i.e.,
is less than or equal to, a hardness value of the glass fiber(s). The hardness
values of the particles and glass fibers can be determined by any
conventional hardness measurement method, such as Vickers or Brinell
hardness, but is preferably determined according to the original Mohs'
hardness scale which indicates the relative scratch resistance of the surface
of a material. The Mohs' Hardness value of glass fibers generally ranges from
about 4.5 to about 6.5, arnd is preferably about 6. R. Weast (Ed.), Handbook
of Chemistry and Physics, CRC Press (1975) at page F-22, which is hereby
incorporated by reference.. In this embodiment, the Mohs' hardness value of
the particles 18 preferably ranges from about 0.5 to about 6. The Mohs'
hardness values of severail non-limiting examples of particles formed from
inorganic materials suitable for use in the present invention are given in
Table
A below.
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Table A
Particle material Mohs' hardness (original scale)
boron nitride about 2"
raphite about 0.5-1'2
molybdenum disulfide about 1'3
talc about 1-1.5'4
mica about 2.8-3.2'5
kaolinite about 2.0-2.5's
ypsum about 1.6-2"
calcite (calcium carbonate) about 3'e
calcium fluorides about 4'9
zinc oxide about 4.52
aluminum about 2.52'
copper about 2.5-322
iron about 4-523
gold about 2.5-324
nickel about 525
palladium about 4.828
platinum about 4.32'
silver about 2.5-42s
" K. Ludema, Friction, Wear. Lubrication, (1996) at page 27, which is hereby
incorporated by
reference.
'2 R. Weast (Ed.), Handbook of chemistry and Physics, CRC Press (1975) at page
F-22.
'3 R. Lewis, Sr., Hawlev's Condensed Chemical Dictionary, (12th Ed. 1993) at
page 793,
which is hereby incorporated by reference.
'° Hawlev's Condensed Chemical Dictionary, (12th Ed. 1993) at page
1113, which is hereby
incorporated by reference.
'S Hawlev's Condensed Chemical Dictionary, (12th Ed. 1993) at page 784, which
is hereby
incorporated by reference.
's Handbook of Chemistry and Ph_ vsics at page F-22.
" Handbook of Chemistry and Ph sits at page F-22.
'8 Friction, Wear, Lubrication at page 27.
'9 Frictions Wear, Lubrication at page 27.
Z° Friction Wear, Lubrication at page 27.
2' Fiction, Wear. Lubrication at page 27.
22 Handbook of Chemistry and Physics at page F-22.
za Handbook of Chemistry and Physics at page F-22.
24 Handbook of Chemistry and Ph~rsics at page F-22.
zs Handbook of Chemistry and Physics at page F-22.
2s Handbook of Chemistry and Physics at page F-22.
2' Handbook of Chemistry and Physics at page F-22.
28 Handbook of Chemistry and Physics at page F-22.
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In another embodinnent of the present invention, the particles 18 are
thermally conductive, i.e., have a thermal conductivity greater than about 30
Watts per meter K, such a,s for example boron nitride, graphite, and the
metallic inorganic solid lubricants discussed above. The thermal conductivity
of a solid material can be .determined by any method known to one skilled in
the art, such as the guarded hot plate method according to ASTM C-177-85
(which is hereby incorporated by reference) at a temperature of about 300K.
In yet another embodiment of the present invention, the particles 18
are electrically insulative or have high electrical resistivity, i.e., have an
electrical resistivity greater than about 1000 microohm-cm, such as for
example boron nitride.
The particles 18 can comprise about 1 to about 80 weight percent of
the coating composition on a total solids basis, preferably about 1 to about
60
weight percent. In one embodiment, the coating composition contains about
20 to about 60 weight percent of particles 18 on total solids basis, and
preferably about 35 to about 55 weight percent, and more preferably about
30 to about 50 weight percent.
It will be appreciated by one skilled in the art that discrete particles 18
of the coating composition can include any combination or mixture of particles
18 discussed above. More specifically, the particles 18 can include additional
discrete particles made from any of the materials described above for forming
the particles 18 in an amount less than the particles 18. These additional
particles are different from the other particles 18 in the resin compatible
coating composition, i.e. the addition particles (1) are chemically different
from the other particles; or' (2) are chemically the same but different in
configuration or properties. The additional particles can comprise up to half
of the particles 18, preferably up to about 15 percent of the particles 18.
In addition to the particles, the coating composition preferably
comprises one or more polymeric film-forming materials, such as organic,
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inorganic and natural polymeric materials. Useful organic polymeric materials
include but are not limited to synthetic polymeric materials, semisynthetic
polymeric materials, natural polymeric materials and mixtures thereof.
Synthetic polymeric materiials include but are not limited to thermoplastic
materials and thermosetting materials. Preferably the polymeric film-forming
materials form a generally continuous film when applied to the surface 16 of
the glass fibers. Generally, the amount of polymeric film-forming materials
can range from about 1 to about 60 weight percent of the coating composition
on a total solids basis, preferably about 5 to about 50 weight percent, and
more preferably about 10 i:o about 30 weight percent.
In one embodiment of the present invention, thermosetting polymeric
film-forming mater7als are lthe preferred polymeric film-forming materials for
use in the coating composition for coating glass fiber strands. Such materials
are compatible with thermosetting matrix materials used as laminates for
printed circuit boards, such as FR-4 epoxy resins, which are polyfunctional
epoxy resins and in one particular embodiment of the invention is a
difunctional brominated epoxy resins. See Electronic Materials HandbookTM,
ASM International (1989) at pages 534-537, which are hereby incorporated
by reference.
Useful thermosetting materials include thermosetting polyesters, epoxy
materials, vinyl esters, phe;nolics, aminoplasts, thermosetting polyurethanes
and mixtures thereof. Suitable thermosetting polyesters include STYPOL
polyesters that are commercially available from Cook Composites and
Polymers of Port Washington, Wisconsin and NEOXIL polyesters that are
commercially available from DSM B.V. of Como, Italy.
A non-limiting example of a thermosetting polymeric material is an
epoxy material. Useful epoxy materials contain at least one epoxy or oxirane
group in the molecule, such as polyglycidyl ethers of polyhydric alcohols or
thiols. Examples of suitable epoxy film-forming polymers include EPON~ 826
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and EPON~ 880 epoxy resins, which are commercially available from Shell
Chemical Company of Houston, Texas.
Useful thermoplastic polymeric materials include vinyl polymers,
thermoplastic polyesters, polyolefins, polyamides {e.g. aliphatic polyamides
or
aromatic polyamides such as aramid), thermoplastic polyurethanes, acrylic
polymers (such as polyacrylic acid) and mixtures thereof.
In another embodiment of the present invention, the preferred
polymeric film-forming material is a vinyl polymer. Useful vinyl polymers in
the
present invention include, but are not limited to, polyvinyl pyrrolidones such
as PVP K-15, PVP K-30, PVP K-60 and PVP K-90, each of which is
commercially available from ISP Chemicals of Wayne, New Jersey. Other
suitable vinyl polymers include Resyn 2828 and Resyn 1037 vinyl acetate
copolymer emulsions which are commercially available from National Starch
Starch and Chemical of Bridgewater, New Jersey, other polyvinyl acetates
such as are commercially available from H. B. Fuller and Air Products and
Chemicals Company of Alle~ntown, Pennsylvania, and polyvinyl alcohols
which are also available from Air Products and Chemicals Company.
Thermoplastic polyesters useful in the present invention include
DESMOPHEN 2000 and DE;SMOPHEN 2001 KS, both of which are
commercially available from Bayer of Pittsburgh, Pennsylvania. Preferred
polyesters include RD-847A polyester resin which is commercially available
from Borden Chemicals of t;olumbus, Ohio, and DYNAKOLL SI 100 resin
which is commercially avail~~ble from Eka Chemicals AB, Sweden. Useful
polyamides include the VERSAM1D products that are commercially available
from General Mills Chemicals, Inc. Useful thermoplastic polyurethanes
include WITCOBOND~ W-:?90H, which is commercially available from Witco
Chemical Corp. of Chicago, Illinois, and RUCOTHANE~ 2011 L polyurethane
latex, which is commercially available from Ruco Polymer Corp. of Hicksville,
New York.
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The aqueous sizing composition of the present invention can comprise
a mixture of one or more thermosetting polymeric materials with one or more
thermoplastic polymeric materials. In one embodiment of the present
invention particularly useful for laminates for printed circuit boards, the
polymeric materials of the aqueous sizing composition comprise a mixture of
RD-847A polyester resin, F'VP K-30 polyvinyl pyrrolidone, DESMOPHEN
2000 polyester and VERSAMID polyamide. In an alternative embodiment
suitable for laminates for printed circuit boards, the polymeric materials of
the
aqueous sizing composition comprise PVP K-30 polyvinyl pyrrolidone,
optionally combined EPON 826 epoxy resin.
Semisynthetic polymeric materials suitable for use as polymeric film-
formers include but are not limited to cellulosics such as
hydroxypropylcellose
and modified starches such as KOLLOTEX 1250 (a low viscosity, low
amylose potato-based starch etherified with ethylene oxide) which is
commercially available from AVEBE of the Netherlands
Natural polymeric m;~terials suitable for use as polymeric film-formers
include but are not limited to starches prepared from potatoes, corn, wheat,
waxy maize, sago, rice, mil~o and mixtures thereof.
It should be appreciated that depending on the nature of the starch,
the starch can function as both a particle 18 and/or a film former. More
specifically, some starches will dissolve completely in a solvent, and in
particular water, and function as a film forming material while others will
not
completely dissolve and will maintain a particular grain size and function as
a
particle 18. Although starches (both natural and semisynthetic) can be used
in accordance with the present invention, the coating composition of the
present invention is preferably essentially free of starch materials. As used
herein the term "essentially free of starch materials" means that the coating
composition comprises less than 20 weight percent on a total solids basis of
the coating composition, preferably less than 5 weight percent and more
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preferably is free of starch rnaterials. Primary sizing compositions
containing
starches that are applied to fiber strands to be incorporated into laminates
for
printed circuit boards are typically not resin compatible and must be removed
prior to incorporation into the polymeric matrix material. As previously
discussed, preferably the coating compositions of the present invention are
resin compatible and do not require removal. More preferably, the coating
compositions of the present: invention are compatible with matrix materials
used to make printed circuit; boards (discussed below) and most preferably
are epoxy resin compatible.
The polymeric film-forming materials can be water soluble,
emulsifiable, dispersible and/or curable. As used herein, "water soluble"
means that the polymeric materials are capable of being essentially uniformly
blended and/or molecularly or ionically dispersed in water to form a true
solution. See Hawley's at page 1075, which is hereby incorporated by
reference. "Emulsifiable" means that the polymeric materials are capable of
forming an essentially stable mixture or being suspended in water in the
presence of an emulsifying agent. See Hawley's at page 461, which is
hereby incorporated by reference. Non-limiting examples of suitable
emulsifying agents are set forth below. "Dispersible" means that any of the
components of the polymeric materials are capable of being distributed
throughout water as finely divided particles, such as a latex. See Hawley's at
page 435, which is hereby incorporated by reference. The uniformity of the
dispersion can be increased by the addition of wetting, dispersing or
emulsifying agents (surfactants), which are discussed below. "Curable"
means that the polymeric materials and other components of the sizing
composition are capable of being coalesced into a film or crosslinked to each
other to change the physical properties of the polymeric materials. See
Hawley's at page 331, which is hereby incorporated by reference.
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In addition to or in lieu of the polymeric film forming materials
discussed above, the coating composition preferably comprises one or more
glass fiber coupling agents such as organo-silane coupling agents, transition
metal coupling agents, phosphonate coupling agents, aluminum coupling
agents, amino-containing Vllerner coupling agents and mixtures thereof.
These coupling agents typically have dual functionality. Each metal or silicon
atom has attached to it one or more groups which can either react with or
compatibilize the fiber surface and/or the components of the resin matrix. As
used herein, the term "compatibilize" means that the groups are chemically
attracted, but not bonded, to the fiber surface and/or the components of the
coating composition, for example by polar, wetting or solvation forces. In one
nonlimiting embodiment, each metal or silicon atom has attached to it one or
more hydrolyzable groups that allow the coupling agent to react with the glass
fiber surface, and one or more functional groups that allow the coupling agent
to react with components of the resin matrix. Examples of hydrolyzable
groups include:
O I-I O R3
II I II I
-OR', -O-C-R2, -~J---C-R2, -O-N=C-R', -O-N=CRS, and
the monohydroxy andlor cyclic C2 C3 residue of a 1,2- or 1,3 glycol, wherein
R' is C,-C3 alkyl; Rz is H or ~~,-C4 alkyl; R3 and R4 are independently
selected
from H, C,-C4 alkyl or Ce-CB aryl; and R~ is C4-C, alkylene. Examples of
suitable compatibilizing or functional groups include epoxy, glycidoxy,
mercapto, cyano, allyl, alkyl, urethano, halo, isocyanato, ureido,
imidazolinyl,
vinyl, acrylato, methacrylatc~, amino or polyarnino groups.
Functional organo-silane coupling agents are preferred for use in the
present invention. Examples of useful functional organo silane coupling
agents include gamma-aminopropyltrialkoxysilanes, gamma-
isocyanatopropyltriethoxysilane, vinyl-trialkoxysilanes,
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glycidoxypropyltrialkoxysilanes and ureidopropyltrialkoxysilanes. Preferred
functional organo-silane coupling agents include A-187 gamma-glycidoxy-
propyltrimethoxysilane, A-174 gamma-methacryloxypropyltrimethoxysilane,
A-1100 gamma-aminopropyltriethoxysilane silane coupling agents, A-1108
amino silane coupling agent and A-1160 gamma-ureidopropyltriethoxysilane
(each of which are commercially available from Witco Corporation OSi
Specialties, Inc. of Tarrytovvn, New York). The organo silane coupling agent
can be at least partially hydrolyzed with water prior to application to the
fibers,
preferably at about a 1:1 stoichiometric ratio or, if desired, applied in
unhydrolyzed form. The pf1 of the water can be modified by the addition of an
acid or a base to initiate or speed the hydrolysis of the coupling agent as is
well known in the art.
Suitable transition metal coupling agents include titanium, zirconium,
yttrium and chromium coupling agents. Suitable titanate coupling agents and
zirconate coupling agents are commercially available from Kenrich
Petrochemical Company. ;iuitable chromium complexes are commercially
available from E.I. duPont de Nemours of Wilmington, Delaware. The amino-
containing Werner-type coupling agents are complex compounds in which a
trivalent nuclear atom such as chromium is coordinated with an organic acid
having amino functionality. Other metal chelate and coordinate type coupling
agents known to those skilled in the art can be used herein.
The amount of coupling agent can range from about 1 to about 30
weight percent of the coating composition on a total solids basis, preferably
about 1 to about 10 weight percent, and more preferably about 2 to about 8
weight percent.
The coating composition can further comprise one or more softening
agents or surfactants that impart a uniform charge to the surface of the
fibers
causing the fibers to repel from each other and reducing the friction between
the fibers, so as to function as a lubricant. Although no required, preferably
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the softening agents are chemically different from other components of the
coating composition. Such .softening agents include cationic, non-ionic or
anionic softening agents and mixtures thereof, such as amine salts of fatty
acids, alkyl imidazoline derivatives such as CATION X, which is commercially
available from Rhone Poulenc of Princeton, New Jersey, acid solubilized fatty
acid amides, condensates of a fatty acid and polyethylene imine and amide
substituted polyethylene imines, such as EMERY~ 6717, a partially amidated
polyethylene imine commercially available from Henkel Corporation of
Kankakee, Illinois. While the coating composition can comprise up to about
60 weight percent of softening agents, preferably the coating composition
comprises less than about 2,0 weight percent and more preferably less than
about 5 weight percent of the softening agents. For more information on
softening agents, see A. J. Hall, Textile Finishing, 2nd Ed. (1957) at pages
108-115, which are hereby incorporated by reference.
The coating composition can further include one or more lubricious
materials that are chemically different from the polymeric materials and
softening agents discussed above to impart desirable processing
characteristics to the fiber strands during weaving. Suitable lubricious
materials can be selected from the group consisting of oils, waxes, greases
and mixtures thereof. Non-limiting examples of wax materials useful in the
present invention include a~~ueous soluble, emulsifiable or dispersible wax
materials such as vegetable:, animal, mineral, synthetic or petroleum waxes,
e.g. paraffin. Oils useful in the present invention include both natural oils,
semisynthetic oils and syntlhetic oils. Generally, the amount of wax or other
lubricious material can range from 0 to about 80 weight percent of the sizing
composition on a total solids basis, preferably from about 1 to about 50
weight percent, more preferably from about 20 to about 40 weight percent,
and most preferably from about 25 to about 35 weight percent.
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Preferred lubricious materials include waxes and oils having polar
characteristics, and more pn~ferably include highly crystalline waxes having
polar characteristics and melting points above about 35°C and more
preferably above about 45°C. Such materials are believed to improve the
wet-out and wet-through of polar resins on fiber strands coated with sizing
compositions containing such polar materials as compared to fiber strands
coated with sizing compositions containing waxes and oils that do not have
polar characteristics. Preferred lubricious materials having polar
characteristics include esters formed from reacting (1 ) a monocarboxlyic acid
and (2) a monohydric alcohol. Non-limiting examples of such fatty acid esters
useful in the present invention include cetyl palmitate, which is preferred
(such as is available from Stepan Company of Maywood, New Jersey as
KESSCO 653 or STEPANTEX 653), cetyl myristate (also available from
Stepan Company as STEPANLUBE 654), cetyl faurate, octadecyl laurate,
octadecyl myristate, octadecyl palmitate and octadecyl stearate. Other fatty
acid ester, lubricious materials useful in the present invention include
trimethylolpropane tripelargonate, natural spermaceti andtriglyceride oils,
such as but not limited to soybean oil, linseed oil, epoxidized soybean oil,
and
epoxidized linseed oil.
While not preferred, the coating composition can include one or more
other lubricious materials, such as non-polar petroleum waxes, in lieu of or
in
addition to of those lubricious materials discussed above. Non-limiting
examples of non-polar petroleum waxes include MICHEM~ LURE 296
microcrystalline wax, POLh'MEKON~ SPP-W microcrystalline wax and
PETROLITE 75 microcryst~~lline wax which are commercially available from
Michelman Inc. of Cincinnati, Ohio and the Petrolite Corporation of Tulsa,
Oklahoma, respectively.
Although not required, if desired the coating composition can also
include a resin reactive diluent to further improve lubrication of the coated
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fiber strands of the present invention and provide good processability in
weaving and knitting by reducing the potential for fuzz, halos and broken
filaments during such manufacturing operations, while maintaining resin
compatibility. As used herein, "resin reactive diluent" means that the
diluent includes functional groups that are capable of chemically reacting
with the same resin with vvhich the coating composition is compatible.
The diluent can be any lubricant with one or more functional groups that
react with a resin system, preferably functional groups that react with an
epoxy resin system, and more preferably functional groups that react with
an FR-4 epoxy resin system. Non-limiting examples of suitable lubricants
include lubricants with amine groups, alcohol groups, anhydride groups,
acid groups or epoxy groups. A non-limiting example of a lubricant with
an amine group is a modifiied polyethylene amine, e.g. EMERY 6717,
which is a partially amidated polyethylene imine commercially available
from Henkel Corporation of Kankakee, Illinois. A non-limiting example of a
lubricant with an alcohol group is polyethylene glycol, e.g. CARBOWAX
300, which is a polyethylE:ne glycol that is commercially available from
Union Carbide of Danbury, Connecticut. A non-limiting example of a
lubricant with an acid group is fatty acids, e.g, stearic acid and salts of
stearic acids. Non-limitinc,~ examples of lubricants with an epoxy group
include epoxidized soybean oil and epoxidized linseed oil, e.g. FLEXOL
LOE, which is an epoxidized linseed oil, and FLEXOL EPO, which is an
epoxidized soybean oil, both commercially available from Union Carbide of
Danbury, Connecticut, and LE-9300 epoxidized silicone emulsion, which is
commercially available from Witco Corporation OSi Specialties, Inc. of
Danbury, Connecticut. Alithough not limiting in the present invention, the
sizing composition can include a resin reactive diluent as discussed above
in an amount up to about 15 weight percent of the sizing composition on
a total solids basis.
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The coating composition can include one or more emulsifying agents
for emulsifying or dispersing components of the sizing composition, such as
the particles 18 and/or lubricious materials. Non-limiting examples of
suitable
emulsifying agents or surfactants include polyoxyalkylene block copolymers
(such as PLURONICTM F-108 polyoxypropylene-polyoxyethylene copolymer
which is commercially available from BASF Corporation of Parsippany, New
Jersey), ethoxylated alkyl phenols (such as IGEPAL CA-630 ethoxylated
octylphenoxyethanol which 'is commercially available from GAF Corporation
of Wayne, New Jersey), polyyoxyethylene octylphenyl glycol ethers, ethylene
oxide derivatives of sorbitol esters (such as TMAZ 81 which is commercially
available BASF of Parsippany, New Jersey), polyoxyethylated vegetable oils
(such as ALKAMULS EL-719, which is commercially available from Rhone
Poulenc), ethoxylated alkylf>henols (such as MACOL OP-10 which is also
commercially available from BASF) and nonylphenol surfactants (such as
MACOL NP-6 which is also commercially available from BASF). Generally,
the amount of emulsifying agent can range from about 1 to about 30 weight
percent of the coating com f~osition on a total solids basis, preferably from
about 1 to about 15 weight percent.
Crosslinking materials, such as melamine formaldehyde, and
plasticizers, such as phthalates, trimellitates and adipates, can also be
included in the coating connposition. The amount of crosslinker or plasticizer
can range from about 1 to about 5 weight percent of the coating composition
on a total solids basis.
Other additives can be included in the coating composition, such as
silicones, fungicides, bactericides and anti-foaming materials, generally in
an
amount of less than about 5 weight percent. Organic and/or inorganic acids
or bases in an amount sufficient to provide the coating composition with a pH
of about 2 to about 10 can also be included in the coating composition. A
non-limiting example of a suitable silicone emulsion is LE-9300 epoxidized
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silicone emulsion, which is c:ommercialfy available from Witco Corporation
OSi Specialties, Inc. of Danbury, Connecticut. An example of a suitable
bactericide is Biomet 66 ani~imicrobial compound, which is commercially
available from M & T Chemicals of Rahway, New Jersey. Suitable anti-
s foaming materials are the SAG materials, which are commercially available
from OSi Specialties, Inc. of Danbury, Connecticut and MAZU DF-136, which
is available from BASF Connpany of Parsippany, New Jersey. Ammonium
hydroxide can be added to the coating composition for coating stabilization,
if desired. Preferably water and more preferably deionized water is included
in the coating composition in an amount sufficient to facilitate application
of a
generally uniform coating upon the strand. The weight percentage of solids
of the coating composition generally ranges from about 1 to about 20 weight
percent.
The coating composition is preferably essentially free of glass
materials. As used herein, "essentially free of glass materials" means that
the
sizing composition comprises less than 20 volume percent of glass matrix
materials for forming glass composites, preferably less than about 5 volume
percent, and more preferably is free of glass materials. Examples of such
glass matrix materials include black glass ceramic matrix materials or
aluminosilicate matrix materials such as are well known to those skilled in
the
art.
In one embodiment for weaving fabric for laminated printed circuit
boards, glass fibers of the coated fiber strand of the present invention have
a
primary layer of a dried residue of an aqueous primary sizing composition
comprising ROPAQUE~ I-IP-1055 or ROPAQUE~ OC-96 styrene acrylic
polymeric synthetic pigments, PVP K-30 polyvinyl pyrrolidone, A-174 acrylic-
functional organo silane coupling agents and A-187 epoxy-functional organo
silane coupling agents, EAIIERY~ 6717 partially amidated polyethylene imine,
STEPANTEX 653 cetyl palmitate, TMAZ 81 ethylene oxide derivatives of
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sorbitol esters, MACOL OP-10 ethoxylated alkylphenol and MAZU DF-136
anti-foaming material.
In another preferred embodiment for weaving fabric for laminated
printed circuit boards, glass fibers of the coated fiber strand of the present
invention have applied thereto a primary layer of a dried residue of an
aqueous primary sizing c~~mposition comprising ROPAQUE~ HL-1055 or
ROPAQUE~ OC-96 styrene-acrylic copolymer hollow spheres, PolarTherm~
160 boron nitride powder andlor ORPAC BORON NITRIDE RELEASECOAT-
CONC dispersion, PVP K: 30 polyvinyl pyrrolidone, A-174 acrylic-functional
organo silane coupling agents and A-187 epoxy-functional organo silane
coupling agents, EMERY~ 6717 partially amidated polyethylene imine,
STEPANTEX 653 cetyl palmitate, TMAZ 81 ethylene oxide derivatives of
sorbitol esters, MACOL OP-10 ethyoxylated alkylphenol, and MAZU DF-136
anti-foaming material.
While not preferred, fiber strands having a residue of a coating
composition similar to those described above that are free of particles 18 can
be made in accordance with the present invention. In particular, it is
contemplated that aqueous, resin compatible sizing compositions including
one or more film-forming polymeric materials, such as PVP K-30 polyvinyl
pyrrolidone; one or more silane coupling agents, such as A-174 acrylic-
functional organo silane coupling agents and A-187 epoxy-functional organo
silane coupling agents; and at least about 25 percent by weight of the sizing
composition on a total solids basis of a lubricious material having polar
characteristics, such as STEPANTEX 653 cetyl palmitate, can be made in
accordance with the pre ent invention. It will be further appreciated by those
skilled in the art that fiber strands having a residue of an aqueous, resin
compatible sizing composition that is essentially free of particles 18 can be
woven into fabrics and made into electronic supports and electronic circuit
boards (as described below) in accordance with the present invention.
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The coating compositions of the present invention can be prepared by
any suitable method such as conventional mixing well known to those skilled
in the art. Preferably the components discussed above are diluted with water
to have the desired weight percent solids and mixed together. The particles
18 can be premixed with water, emulsified or otherwise added to one or more
components of the coating composition prior to mixing with the remaining
components of the coating.
Sizing compositions according to the present invention can be applied
in many ways, for example: by contacting the filaments with a roller or belt
applicator, spraying or other means. The sized fibers are preferably dried at
room temperature or at elevated temperatures. The dryer removes excess
moisture from the fibers and, if present, cures any curable sizing composition
components. The temperature and time for drying the glass fibers will
depend upon such variables as the percentage of solids in the sizing
composition, components of the sizing composition and type of glass fiber.
The amount of the coating composition present as a dried residue on
the fiber strand is preferably less than about 30 percent by weight, more
preferably less than about 10 percent by weight and most preferably less than
about 5 percent by weight as measured by loss on ignition (LOI). In one
embodiment of the invention, the LOI is less than 1 percent by weight. As
used herein the term "loss on ignition" means the weight percent of dried
coating composition present on the surface of the fiber strand as determined
by the following equation (Eq.1 ):
LOI= 100 x [(Wd~; Wba,~)IWd~,] Eq. 1
wherein Wary is the weight of the fiber strand plus the residue of the coating
composifion after drying iin an oven at about 220°F (about
104°C) for about
60 minutes and Wba~ is the weight of the bare fiber strand after removal of
residue of the coating composition by heating the fiber strand in an oven at
about 1150°F (about 621 °C) for about 20 minutes.
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After the application of the primary size, the fibers are gathered into
strands having 2 to about 15,000 fibers per strand, and preferably about 100
to about 1600 fibers per strand..
A secondary layer of a secondary sizing or secondary coating
composition can be applied over the primary layer in an amount effective to
coat or impregnate the portion of the strands, for example by dipping the
coated strand in a bath containing the secondary coating composition,
spraying the secondary coating composition upon the coated strand or by
contacting the coated strand with an applicator as discussed above. The
coated strand can be pawed through a die to remove excess coating
composition from the strand andlor dried as discussed above for a time
sufficient to at least partially dry or cure the secondary coating
composition.
The method and apparatus for applying the secondary coating composition to
the strand is determined in part by the configuration of the strand material.
The strand is preferably clried after application of the secondary coating
composition in a manner well known in the art.
Suitable secondary coating compositions can include one or more film-
forming materials, lubricants and other additives such as are discussed
above. The secondary coating is preferably different from the primary sizing
composition, i.e. it (1) contains at least one component which is chemically
different from the components of the sizing composition; or (2) contains at
least one component in an amount which is different from the amount of the
same component contained in the sizing composition. Non-limiting examples
of suitable secondary coating compositions including polyurethane are
disclosed in U.S. Patent Nos. 4,762,750 and 4,762,751, which are hereby
incorporated by reference.
Referring now to Fig. 2, in an alternative embodiment according to the
present invention, the glass fibers 212 of the coated fiber strand 210 can
having applied thereto a primary layer 214 of a dried residue of a primary
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sizing composition which can include any of the sizing components in the
amounts discussed above. Examples of suitable sizing compositions are set
forth in Loewenstein at pages 237-291 (3d Ed. 1993) and U.S. Patent Nos.
4,390,647 and 4,795,678, each of which is hereby incorporated by reference.
A secondary layer 215 of a secondary coating composition is applied to at
least a portion, and preferably over the entire outer surface, of the primary
layer 214. The secondary coating composition comprises one or more types
of discrete particles 216 :such as are discussed in detail above. The amount
of
particles in the secondan~ coating composition can range from about 1 to
about 99 weight percent on a total solids basis and preferably about 20 to
about 90 weight percent. The percentage of solids of the aqueous secondary
coating composition genE:rally ranges from about 5 to about 50 weight
percent.
In an alternative embodiment, the particles of the secondary coating
composition comprise hydrophilic inorganic solid particles that absorb and
retain water in the interstices of the hydrophilic particles. The hydrophilic
inorganic solid particles c;an absorb water or swell when in contact with
water
or participate in a chemical reaction with the water to form, for example, a
viscous gel-like solution which blocks or inhibits further ingress of water
into
the interstices of a telecommunications cable which the coated glass fiber
strand is used to reinforce. As used herein, "absorb" means that the water
penetrates the inner structure or interstices of the hydrophilic material and
is
substantially retained therein. See Hawley's Condensed Chemical Dictionary
at page 3, which is hereby incorporated by reference. "Swell" means that the
hydrophilic particles expand in size or volume. See Webster's New Colle iq ate
Dictionary (1977) at page 1178, which is hereby incorporated by reference.
Preferably, the hydrophilic particles swell after contact with water to at
least
one and one-half times their original dry weight, and more preferably about
two to about six times their original weight. Non-limiting examples of
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hydrophilic inorganic soficl lubricant particles that swell include smectites
such
as vermiculite and montmorillonite, absorbent zeolites and inorganic
absorbent gets. Preferably, these hydrophilic particles are applied in powder
form over tacky sizing or ~ather tacky secondary coating materials. The
amount of hydrophilic inorganic particles in this embodiment of the secondary
coating composition can range from about 1 to about 99 weight percent on a
total solids basis and preiferably about 20 to about 90 weight percent.
In an alternative embodiment shown in Fig. 3, a tertiary layer 320 of a
tertiary coating composition can be applied to at least a portion of the
surface,
and preferably over the entire surface, of a secondary layer 315, i.e. such a
fiber strand 312 would h~we a primary layer 314 of a primary sizing, a
secondary layer 315 of a secondary coating composition and a tertiary, outer
layer 320 of the tertiary coating. The tertiary coating is preferably
different
from the primary sizing composition and the secondary coating composition,
i.e. the tertiary coating composition (1) contains at least one component
which
is chemically different from the components of the primary sizing and
secondary coating composition; or (2) contains at least one component in an
amount which is differenit from the amount of the same component contained
in the primary sizing or secondary coating composition.
In this embodiment, the secondary coating composition comprises one
or more polymeric materials discussed above, such as polyurethane, and the
tertiary powdered coatin~~ composition comprises solid particles, such as the
PolarTherm~ boron nitride particles, and hollow particles, such as
ROPAQUE~ pigments, which are discussed above. Preferably, the
powdered coating is applied by passing the strand having a liquid secondary
coating composition applied thereto through a fluidized bed or spray device to
adhere the powder particles to the tacky secondary coating composition.
Alternatively, the strands can be assembled into a fabric 810 before the layer
812 of tertiary coating is applied, as shown in Fig. 8. The weight percent of
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powdered solid particles adhered to the coated fiber strand 310 can range
from about 0.1 to about 30 weight percent of the total weight of the dried
strand.
The tertiary powdered coating can also include one or more polymeric
materials such as are discussed above, such as acrylic polymers, epoxies, or
polyolefins, conventional stabilizers and other modifiers known in the art of
such coatings, preferably in dry powder form.
The coated fiber strands 10, 210, 310 discussed above can be used as
continuous strand or further processed into diverse products such as chopped
strand, twisted strand, roving andlor fabric, such as wovens, nonwovens,
knits and mats. In addition, the coated fiber strands used as warp and weft
(i.e. fill) strands of a fabric can be non-twisted (also referred to as
untwisted or
zero twist) or twisted prior i:o weaving and the fabric can include various
combinations of both twisted and non-twisted warp and weft strands.
Although the prior discussion is generally directed toward applying
the coating composition of the present invention directly on glass fibers
after fiber forming and subsequently incorporating the fibers into a fabric,
it
should be appreciated by those skilled in the art that the present invention
also includes an embodiment wherein the coating composition of the
present invention is applied to a fabric after it has been manufactured
using various techniques vuell known in the art. Depending on the
processing of the fabric, the coating composition of the present invention
can be applied either directly to the glass fibers in the fabric or to another
coating already on the gla:ys fibers and/or fabric. For example, the glass
fibers can be coated with a conventional starch-oil sizing after forming and
woven into a fabric. The fabric can then be treated to remove starch-oil
sizing prior to applying the. coating composition of the present invention.
This sizing removal can bE: accomplished using techniques well known in
the art, such as thermal treatment or washing of the fabric. In this
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instance, the coating composition would directly coat the surface of the
fibers of the fabric. If any portion of the sizing composition initially
applied
to the glass fibers after forrning is not removed, the coating composition of
the present invention would then be applied over the remaining portion of
the sizing composition rather than directly to the fiber surface.
In another embodiment of the present invention, selected
components of the coating composition of the present invention can be
applied to the glass fibers immediately after forming and the remaining
components of the coating composition can be applied to the fabric after it
is made. In a manner similar to that discussed above, some or all of the
selected components can be removed from the glass fibers prior to
coating the fibers and fabric with the remaining components. As a result,
the remaining components will either directly coat the surface of the fibers
of the fabric or coat those :;elected components that were not removed
from the fiber surface.
The coated fiber strands 10, 210, 310 and products formed therefrom
can be used in a wide variety of applications, but are preferably used as
reinforcements 410 for reinforcing polymeric matrix materials 412 to form a
composite 414, such as is shown in Fig. 4, which will be discussed in detail
below. Such applications include but are not limited to laminates for printed
circuit boards, reinforcements for telecommunications cables, and various
other composites.
One advantage of the coated strands of the present invention is that
they are compatible with t,~pical polymeric matrix resins used to make
electronic supports and printed circuit board and are suitable for use on air-
jet
looms, which are commonly used to make the reinforcing fabrics for such
applications. Conventional sizing compositions applied to fibers to be woven
using air-jet looms include components (such as starches and oils) that are
generally not compatible vvith such resin systems. It has been observed that
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weaving characteristics of fiber strands coated with a residue of a primary
sizing composition comprising particles 18 in accordance with the present
invention approximate the weaving characteristics of fiber strands coated with
conventional starch/oil based sizing compositions and are compatible with
FR-4 epoxy resins. Although not meant to be bound by any particular theory,
it is hypothesized that the particles 18 of the instant invention function in
a
manner similar to the starcri component of conventional starchloil sizing
compositions during processing and air jet weaving by providing the
necessary fiber separation and air drag for the air jet weaving operation
while
further providing compatibility with the epoxy resin system that is not
typical of
conventional starch/oil sizing compositions. More specifically, the particles
18
contribute a dry, powder characteristic to the coating similar to the dry
lubricant charactistics of a starch coating.
Another advantage of the coated strands of the present invention is
that the particles provide interstices between the fibers of the strand which
facilitate flow of the matrix materials therebetween to more quickly and/or
uniformly wet-out and wet-through the fibers of the strand. Surprisingly, the
amount of particles can exceed 20 weight percent of the total solids of the
coating composition applied to the fibers, yet still be adequately adhered to
the fibers and provide strartds having handling characteristics at least
comparable to strands without the particle coating.
In another embodiment shown in Fig. 5, coated fiber strands 510 made
according to the present invention can be used as warp and/or weft strands
514, 516 in a knit or woven fabric 512 reinforcement, preferably to form a
laminate for a printed circuit board (shown in Figs. 6-8). Although not
required, the warp strands 514 can be twisted prior to use by any
conventional twisting technique known to those skilled in the art, for example
by using twist frames to impart twist to the strand at about 0.5 to about 3
turns
per inch. The reinforcing fiabric 512 can include about 5 to about 100 warp
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strands 514 per centimeter (about 13 to 254 warp strand per inch) and
preferably has about 6 to about 50 weft strands per centimeter (about 15 to
about 127 weft strands per inch). The weave construction can be a regular
plain weave or mesh (shown in Fig. 5), although any other weaving style well
known to those skilled in the art, such as a twill weave or satin weave, can
be
used.
A suitable woven reinforcing fabric 512 can be formed by using any
conventional loom well known to those skilled in the art, such as a shuttle
loom, air jet loom or rapier loom, but preferably is formed using an air jet
loom
(discussed above). Preferred air jet looms are commercially available from
Tsudakoma of Japan as Model Nos. 103, 103I 1033 or ZAX; Sulzer Ruti
Model Nos. L-5000, L-510() or L-5200 which are commercially available from
Sulzer Brothers LTD. of Zurich, Switzerland; and Toyoda Model No. JAT610.
The fabric of the present invention is preferably woven in a style
which is suitable for used in a laminate for an electronic support or printed
circuit board, such as are disclosed in "Fabrics Around the World", a
technical bulletin of Clark-Schwebel, fnc. of Anderson, South Carolina
( 1995), which is hereby incorporated by reference. For example, a non
limiting fabric style using E225 E-glass fiber yarns is Style 21 16, which
has 118 warp yarns and 114 fill (or weft) yarns per 5 centimeters (60
warp yarns and 58 fill yarns per inch); uses 7 22 1 x0 (E225 1 /0) warp
and fill yarns; has a nominal fabric thickness of about 0.094 millimeters
(about 0.037 inches); and a fabric weight (or basis weight) of about
103.8 grams per square meter (about 3.06 ounces per square yard). A
non-limiting example of a fabric style using G75 E-glass fiber yarns is
Style 7628, which has 8'7 warp yarns and 61 fill yarns per 5 centimeters
(44 warp yarns and 31 fill yarns per inch?; uses 9 68 1 x0 (G75 1 /0) warp
and fill yarns; has a nominal fabric thickness of about 0.173 millimeters
(about 0.0068 inches); and a fabric weight of about 203.4 grams per
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square meter (about 6.00 ounces per square yard). A non-limiting
example of a fabric style using D450 E-glass fiber yarns is Style 1080,
which has 118 warp yarns. and 93 fill yarns per 5 centimeters (60 warp
yarns and 47 fill yarns per inch); uses 5 1 1 1 x0 (D450 1 /0) warp and fill
yarns; has a nominal fabric: thickness of about 0.053 millimeters (about
0.0021 inches); and a fabric weight of about 46.8 grams per square
meter (about 1.38 ounces per square yard). A non-limiting example of a
fabric style using D900 E-~~lass fiber yarns is Style 106, which has 1 10
warp yarns and 1 10 fill yarns per 5 centimeters (56 warp yarns and 56 fill
yarns per inch); uses 5 5.5 1 x0 (D900 1 /0) warp and fill yarns; has a
nominal fabric thickness of about 0.033 millimeters (about 0.013 inches);
and a fabric weight of about 24.4 grams per square meter (about 0.72
ounces per square yard). Another non-limiting example of a fabric style
using D900 E-glass fiber yarns is Style 108, which has 1 18 warp yarns
and 93 fill yarns per 5 centimeters (60 warp yarns and 47 fill yarns per
inch); uses 5 5.5 1 x2 (D9~00 1 /2) warp and fill yarns; has a nominal fabric
thickness of about 0.061 millimeters (about 0.0024 inches); and a fabric
weight of about 47.5 grarns per square meter (about 1.40 ounces per
square yard). A non-limiting example of a fabric style using both E225
and D450 E-glass fiber yarns is Style 2113, which has 1 18 warp yarns
and 110 fill yarns per 5 centimeters f60 warp yarns and 56 fill yarns per
inch); uses 7 22 1 x0 (E22:5 1 /0) warp yarn and 5 1 1 1 x0 ID450 1 /0) fill
yarn; has a nominal fabric thickness of about 0.079 millimeters (about
0.0031 inches); and a fabric weight of about 78.0 grams per square
meter (about 2.30 ounces, per square yard). A non-limiting example of a
fabric style using both G50 and G75 E-glass fiber yarns is Style 7535
which has 87 warp yarns and 57 fill yarns per 5 centimeters (44 warp
yarns and 29 fill yarns per inch); uses 9 68 1 x0 (G75 1 /0) warp yarn and
9 99 1 x0 (G50 1 /0) fill yarn; has a nominal fabric thickness of about
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0.201 millimeters (about 0.0079 inchesl; and a fabric weight of about
232.3 grams per square meter (about 6.85 ounces per square yard).
These and other useful fabric style specification are given in IPC-EG-140
"Specification for Finished Fabric Woven from 'E' Glass for Printed
Boards", a publication of 1'he Institute for Interconnecting and Packaging
Electronic Circuits (June 1997), which is hereby incorporated by
reference. Although the aforementioned fabric styles use twisted yarns, it
is contemplated that these; or other fabric styles using zero-twist yarns or
rovings in conjunction witlh or in lieu of twisted yarns can be made in
accordance with the present invention. It is further contemplated that
some or all of the warp yarn in the fabric can have fibers coated with a
first resin compatible sizing composition and some or all of the fill yarn
can have fibers coated with a second resin compatible coating different
from the first composition, i.e. the second composition (1) contains at least
one component which is chemically different from the components of the first
sizing composition; or (2) contains at least one component in an amount
which is different from the amount of the same component contained in the
first sizing composition.
It should be appreciated that the laminates can also be a unidirectional
laminate wherein most of tlhe fibers, yarns or strands in each layer of fabric
are oriented in the same direction.
Referring now to Fid. 6, the fabric 612 can be used to form a
composite or laminate 614 by coating and/or impregnating with a polymeric
film-forming thermoplastic or thermosetting matrix material 616. The
composite or laminate 614 is suitable for use as a electronic support. As
used herein, "electronic support" means a structure that mechanically
supports andlor electrically interconnects elements including but not limited
to
active electronic components, passive electronic components, printed circuits,
integrated circuits, semiconductor devices and other hardware associated
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with such elements including but not limited to connectors, sockets, retaining
clips and heat sinks.
Matrix materials useiful in the present invention include thermosetting
materials such as thermosetting polyesters, vinyl esters, epoxides (containing
at least one epoxy or oxirane group in the molecule, such as polyglycidyl
ethers of polyhydric alcoho~ls or thiols), phenolics, aminoplasts,
thermosetting
polyurethanes, derivatives .and mixtures thereof. Preferred matrix materials
for forming laminates for printed circuit boards are FR-4 epoxy resins,
polyimides and liquid crystalline polymers, the compositions of which are well
know to those skilled in the art. If further information regarding such
compositions is needed, se:e Electronic Materials HandbookTM, ASM
International (1989) at pages 534-537.
Non-limiting examples of suitable polymeric thermoplastic matrix
materials include polyolefins, polyamides, thermoplastic polyurethanes and
thermoplastic polyesters, vinyl polymers and mixtures thereof. Further
examples of useful thermoplastic materials include polyimides, polyether
sulfones, polyphenyl sulfones, polyetherketones, polyphenylene oxides,
polyphenylene sulfides, po~lyacetals, polyvinyl chlorides and polycarbonates.
Other components which can be included with the polymeric matrix
material and reinforcing material in the composite include colorants or
pigments, lubricants or processing aids, ultraviolet light (UV) stabilizers,
antioxidants, other fillers and extenders.
The fabric 612 can be coated and impregnated by dipping the fabric
612 in a bath of the polymeric matrix material 616, for example, as discussed
in R. Tummala (Ed.), Micr~~electronics Packaging Handbook, (1989) at pages
895-896, which are hereby incorporated by reference. More generally,
chopped or continuous fiber strand reinforcing material can be dispersed in
the matrix material by hand or any suitable automated feed or mixing device
which distributes the reinforcing material generally evenly throughout the
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polymeric matrix material. f=or example, the reinforcing material can be
dispersed in the polymeric rnatrix material by dry blending all of the
components concurrently or sequentially.
The polymeric matrix: material 616 and strand can be formed into a
composite or laminate 614 by a variety of methods which are dependent upon
such factors as the type of polymeric matrix material used. For example, for a
thermosetting matrix material, the composite can be formed by compression
or injection molding, pultrus;ion, filament winding, hand lay-up, spray-up or
by
sheet molding or bulk molding followed by compression or injection molding.
Thermosetting polymeric matrix materials can be cured by the inclusion of
crosslinkers in the matrix material and/or by the application of heat, for
example. Suitable crosslinkers useful to crosslink the polymeric matrix
material are discussed above. The temperature and curing time for the
thermosetting polymeric m~~trix material depends upon such factors as the
type of polymeric matrix m~~terial used, other additives in the matrix system
and thickness of the composite, to name a few.
For a thermoplastic matrix material, suitable methods for forming the
composite include direct molding or extrusion compounding followed by
injection molding. Method:; and apparatus for forming the composite by the
above methods are discussed in I. Rubin, Handbook of Plastic Materials and
Technoloay (1990) at pagers 955-1062, 1179-1215 and 1225-1271, which are
hereby incorporated by reference.
In a particular embodiment of the invention shown in Fig. 7, composite
or laminate 710 includes f<~bric 712 impregnated with a compatible matrix
material 714. The impregnated fabric can then be squeezed between a set of
metering rolls to leave a measured amount of matrix material, and dried to
form an electronic support in the form of a semicured substrate or prepreg.
An electrically conductive layer 720 can be positioned along a portion of a
side 722 of the prepreg in a manner to be discussed below in the
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specification, and the prepre:g is cured to form an electronic support 718
with
an electrically conductive layer. In another embodiment of the invention, and
more typically in the electronic support industry, two or more prepregs are
combined with one or more electrically conductive layers and laminated
together and cured in a mariner well known to those skilled in the art, to
form
a multilayered electronic support. For example, but not limiting the present
invention, the prepreg stack can be laminated by pressing the stack, e.g.
between polished steel plates, at elevated temperatures and pressures for a
predetermined length of time to cure the polymeric matrix and form a laminate
of a desired thickness. A portion of one or more of the prepregs can be
provided with an electrically conductive layer either prior to or after
lamination
and curing such that the re~~ulting electronic support is a laminate having at
least one electrically conductive layer along a portion of an exposed surface
(hereinafter referred to as a "clad laminate").
Circuits can then be formed from the electrically conductive layers) of
the single layer or multilayered electronic support using techniques well
known in the art to construct an electronic support in the form of a printed
circuit board or printed wiring board (hereinafter collectively referred to as
"electronic circuit boards"). If desired, apertures or holes (also referred to
as
"vias") can be formed in the: electronic supports, to allow for electrical
interconnection between circuits and/or components on opposing surfaces of
the electronic support, by any convenient manner known in the art, including
but not limited to mechanical drilling and laser drilling. More specifically,
after
formation of the apertures, a layer of electrically conductive material is
deposited on the walls of the aperture or the aperture is filled with an
electrically conductive material to facilitate the required electrical
interconnection and/or heat dissipation.
The electrically conductive layer 720 can be formed by any method
well known to those skilled in the art. For example but not limiting the
present
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invention, the electrically conductive layer can be formed by laminating a
thin
sheet or foil of metallic material onto at least a portion of a side of the
semi-
cured or cured prepreg or laminate. As an alternative, the electrically
conductive layer can be fonred by depositing a layer of metallic material onto
at least a portion of a side of the semi-cured or cured prepreg or laminate
using well known techniques including but not limited to electrolytic plating,
electroless plating or sputtering. Metallic materials suitable for use as an
electrically conductive layer include but are not limited to copper (which is
preferred), silver, aluminum, gold, tin, tin-lead alloys, palladium and
combinations thereof.
In another embodiment of the present invention, the electronic support
can be in the form of a multilayered electronic circuit board constructed by
laminating together one or amore electronic circuit boards (described above)
with one or more clad laminates (described above) andlor one or more
prepregs (described above). If desired, additional electrically conductive
layers can be incorporated into the electronic support, for example along a
portion of an exposed side of the multilayered electronic circuit board.
Furthermore, if required, additional circuits can be formed from the
electrically
conductive layers in a manner discussed above. It should be appreciated that
depending on the relative ~~ositions of the layers of the multilayered
electronic
circuit board, the board can have both internal and external circuits.
Additional apertures are formed, as discussed earlier, partially through or
completely through the board to allow electrical interconnection between the
layers at selected location;>. It should be appreciated that the resulting
structure can have some apertures that extend completely through the
structure, some apertures 'that extend only partially through the structure,
and
some apertures that are completely within the structure.
The instant invention further contemplates the fabrication of
multilayered laminates and electronic circuit boards which include at least
one
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composite layer made according to the teachings herein and at least one
composite layer made in a manner different from the composite layer taught
herein, e.g. made using conventional glass fiber composite technology. More
specifically and as is well known to those skilled in the art, traditionally
the
filaments in continuous glass fiber strands used in weaving fabric are treated
with a starch/oil sizing which includes partially or fully dextrinized starch
or
amylose, hydrogenated vegetable oil, a cationic wetting agent, emulsifying
agent and water, including Ibut not limited to those disclosed in I_oewenstein
at pages 237-244 (3d Ed. 1993), which is hereby incorporated by reference.
Warp yarns produced from these strands are thereafter treated with a solution
prior to weaving to protect the strands against abrasion during the weaving
process, e.g. poly(vinyl alcohol) as disclosed in U.S. Patent No. 4,530,876 at
column 3, line 67 through column 4, line 11, which is hereby incorporated by
reference. This operation i,s commonly referred to as slashing. The polyvinyl
alcohol) as well as the starc;h/oil size are generally not compatible with the
polymeric matrix material used by composite manufacturers and the fabric
must be cleaned to remove essentially all organic material from the surface of
the glass fibers prior to impregnating the woven fabric. This can be
accomplished in a variety ways, for example by scrubbing the fabric or, more
commonly, by heat treating the fabric in a manner well known in the art. As a
result of the cleaning operation, there is no suitable interface between the
polymeric matrix material used to impregnate the fabric and the cleaned glass
fiber surface, so that a coupling agent must be applied to the glass fiber
surface. This operation is sometime referred to by those skilled in the art as
finishing. The coupling agents most commonly used in finishing operations
are silanes, including but not limited to those disclosed in E. P.
Plueddemann,
Silane Coupling Aqents (1182) at pages 146-147, which is hereby
incorporated by reference. Also see Loewenstein at pages 249-256 (3d Ed.
1993). After treatment with the silane, the fabric is impregnated with a
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compatible polymeric matrix material, squeezed between a set of metering
rolls and dried to form a semicured prepreg as discussed above. It should be
appreciated that depending on the nature of the sizing, the cleaning operation
andlor the matrix resin ust:d in the composite, the slashing and/or finishing
steps can be eliminated. ~~ne or more prepregs incorporating conventional
glass fiber composite technology can then be combined with one or more
prepregs incorporating the; instant invention to form an electronic support as
discussed above, and in particular a multilayered laminate or electronic
circuit
board. For more information regarding fabrication of electronic circuit
boards,
see Electronic Materials HlandbookTM, ASM International (1989) at pages 113-
115, R. Tummala (Ed.), Microelectronics Packagina Handbook, (1989) at
pages 858-861 and 895-909, M. W. Jawitz, Printed Circuit Board Handbook
(1997) at pages 9.1-9.42, and C. F. Coombs, Jr. (Ed.), Printed Circuits
Handbook, (3d Ed. 1988), pages 6.1-6.7, which are hereby incorporated by
reference.
The composites and laminates forming the etectronic supports of the
instant invention can be u:,ed to form packaging used in the electronics
industry, and more particularly first, second and/or third level packaging,
such
as that disclosed in Tumm~ala at pages 25-43, which is hereby incorporated
by reference. In addition, the present invention can also be used for other
packaging levels.
The present invention also includes a method for reinforcing a
polymeric matrix material to form a composite. The method comprises:
(1 ) applying to a glass fiber strand reinforcing material the above primary
sizing, secondary coating and/or tertiary coating composition including
particles which provide interstitial spaces between adjacent glass fibers of
the
strand, (2) drying the coating to form a substantially uniform coating upon
the
reinforcing material; (3) combining the reinforcing material with the
polymeric
matrix material; and (4) at feast partially curing the polymeric matrix
material
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to provide a reinforced polynneric composite in a manner such as is discussed
in detail above. Although not limiting the present invention, the reinforcing
material can be combined with the polymeric matrix material, for example by
dispersing it in the matrix material.
The present invention also includes a method for inhibiting adhesion
between adjacent glass fibers of a glass fiber strand, comprising the steps
of:
(1 ) applying to a glass fiber atrand the above primary sizing, secondary
coating or tertiary coating composition including particles which provide
interstitial spaces between adjacent glass fibers of the strand; (2) drying
the
coating to form a substantially uniform coating upon the glass fibers of the
glass fiber strand, such that adhesion between adjacent glass fibers of the
strand is inhibited.
The present invention will now be illustrated by the following specific,
non-limiting examples.
EXAMPLE 1
Each of the components in the amounts set forth in Table 1 were
mixed to form aqueous primary size compositions A, B and C according to the
present invention. Each aqueous primary sizing composition was prepared in
a similar manner to that discussed above. Less than about 1 weight percent
of acetic acid on a total weight basis was included in each composition. Each
of the aqueous sizing compositions of Table 1 was coated onto fibers forming
G-75 E-glass fiber strands.
Each of the coated gilass fiber strands was dried, twisted to form yarn,
and wound onto bobbins in a similar manner using conventional twisting
equipment. The yarns coai:ed with the sizing compositions exhibited minimal
sizing shedding during twisting.
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Table 1
WEIGHT
PERCENT
OF
COMPONENT
ON TOTAL
SOLIDS
BASIS
Samp le
COMPONENT A B C
Polyvinyl pyrrolidone~~14.7 14.7 13.4
Ce I Palmitates~ 30.0 29.9 _ 27.3
~~
Epoxy-functional orga~no1.8 1.8 1.6
silane coupling agent31
Acrylic-functional 3.7 3.7 3.3
organo-
silane coupling agent32
Softenin Agent 3~~ 2.4 2.4
Emulsi in Agents 1.6 1.6 1.5
Emulsifying Agents 3.3 3.3 3.0
Antifoamin A ents 0.2 0.2 0.2
Styrene/Acrylic Copolymer0 42.4 0
Hollow Particle
Dispersion37
Styrene/Acrylic Copolymer42.3 0 38.6
Hollow Particle
Dispersion38
Boron Nitride Dispersions0 0 6.3
Boron Nitride Powder~~ 0 0 2.6
~' PVP K-30 polyvinyl pyrrolidone which is commercially available from ISP
Chemicals of
Wayne, NJ.
so STEPANTEX 653 which is commercially available from Stepan Company of
Maywood, NJ
3' A-187 gamma-glycidoxypropyltrimethoxysilane which is commercially available
from OSi
Specialties, Inc. of Tarrytown, NY'.
32 A_174 gamma-methacryloxypropyltrimethoxysilane which is commercially
available from
OSi Specialties, Inc. of Tarrytown, NY.
3' EMERY~ 6717 partially amidated polyethylene imine which is commercially
available from
Henkel Corporation of Kankakee, IL.
sa MACOL OP-10 ethoxylated alkylphenol which is commercially available from
BASF Corp. of
Parsippany, NJ.
35 TMAZ-81 ethylene oxide derivative of a sorbitol ester which is commercially
available from
BASF Corp. of Parsippany, NJ.
~ MAZU DF-136 antifoaming agE;nt which is commercially available from BASF
Corp. of
Parsippany, NJ.
3' ROPAQUE~ HP-1055, 1.0 micron particle dispersion which is commercially
available from
Rohm and Haas Company of Philadelphia, PA.
~ ROPAQUE~ OP-96, 0.55 micron particle dispersion which is commercially
available from
Rohm and Haas Company of Philadelphia, PA.
39 ORPAC BORON NITRIDE RELEASECOAT-CONC boron nitride dispersion which is
commercially available from ZYF~ Coatings, Inc. of Oak Ridge, TN.
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Yarns sized with the each of the sizing compositions (A, B and C) were
used as fill yarn in weaving a 7628 style fabric using a Sulzer Ruti Model
5200 air jet loom. The warp yarn was a twisted G-75 E-glass fiber strand with
fiber coated with a different resin compatible sizing composition4'. The
fabrics
were subsequently pre-prec~ged with an FR-4 epoxy resin having a Tg of
about 140°C (designated 4000-2 resin by Nelco International Corporation
of
Anaheim, CA). The sizing .compositions were not removed from the fabric
prior to pre-pregging. Lamiinates were made by stacking 8-plies of the pre-
pregged material between itwo layers of 1 ounce copper and laminating them
together at a temperature of about 355°F (about 179°C), pressure
of about
300 pounds per square inch (about 2.1 megaPascals) for about 150 minutes
(total cycle time). The thickness of the laminates without copper ranged from
about 0.043 inches (about 0.11 centimeters) to about 0.050 inches (0.13
centimeters).
After forming, the laminates (designated A, B and C according to the
fiber strands from which they were made) were tested as indicated below in
Table 2. During testing, laminate B tested at the same time as a first
laminate
made from glass fiber yarn coated with sizing composition Sample A
(hereinafter designated as Laminate Sample A1 ). At a later date, laminate C
was tested at the same time as a second laminate made from glass fiber yarn
coated with sizing composition Sample C (hereinafter designated as Laminate
Sample A2).
4o PolarTherm~ PT 160 boron nitride powder which is commercially available
from Advanced
Ceramics Corporation of Lakewood, OH.
4' The warp yarn was PPG Industries, Inc.'s commercially available fiber glass
yarn product
designated as G-75 glass fiber yarn coated with PPG Industries, Inc.'s 1383
binder.
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Table 2
Laminate
Sample
Test Units A1* B* A2** C**
Average inches 0.048 0.048 0.053- 0.053-
Thickness 0.055 0.055
Solder Float seconds 409 386 235 253
Solder Dip seconds 320 203 243 242
Flexural Strengthkpsi 99 102 91 90
Warp Direction4z
Flexural Strengthkpsi 86 81 73 72
Weft Direction4s
based on 2 samples
** based on 3 samples
The solder float test was conducted by floating an 4 inch by 4 inch
square (10.16 centimeters by 10.16 centimeters) of the copper clad laminate
in a eutectic lead-tin solder bath at about 550°F (about 288°C)
until blistering
or delamination was observed. The time until the first blister or delamination
was then recorded in seconds.
The solder dip test was conducted by cutting a sample of the laminate,
removing the copper from the sample by etching, smoothing the cut edges of
the sample by polishing and placing the sample in a pressure cooker at
250°F
(about 121 °C) and 15 pounds per square inch (about 0.1 megaPascals)
for
about 60 minutes. After the 60 minute exposure, the sample was removed
from the pressure cooker, patted dry and dipped into a eutectic lead-tin
solder
bath at about 550°F (about 288°C) until blistering or
delamination was
observed. The time until the first blister or delamination was then recorded
in
seconds.
The flexural testing was conducted according to the IPC standard
indicated.
az Per IPC-TM-650 "Flexural Strength of Laminates (At Ambient Temperature)",
12/94,
Revision B.
'3 /bid.
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The laminates A, B and C made using fiber strands sized with sizing
compositions A, B and C respectively, had acceptable properties (shown in
Table 2) for use as electronic supports for printed circuit boards.
EXAMPLE 2
Each of the components in the amounts set forth in Table 3 were
mixed to form aqueous size composition Samples D, E and F according to
the present invention. Less than about 0.5 weight percent of acetic acid
on a total weight basis was included in each composition.
Table 3
WEIGHT
PERCENT
OF COMPONENT
ON TOTAL
SOLIDS
BASIS
Sam le
COMPONENT D E F
pol vin I rrolidone''~ 12.3 11.7 12.3
cet I almitate45 25.0 23.9 25.0
emulsif in a ent4s 3.5 3.9 2.7
emulsif in a ent4' 1.8 2.0 1.4
boron nitride powder 2.4 2.3 2.4
articles48
cationic lubricant49 2.0 2.0 2.0
acrylic-functional organo-silane3.1 2.9 3.1
cou lin a ent 60
a oxy-functional or ano-silane1.5 1.4 1.5
°° PVP K-30 polyvinyl pyrrolidone which is commercially
available from ISP Chemicals of
Wayne, NJ.
°s STEPANTEX 653 cetyl palmitate which is commercially available from
Stepan Company of
Chicago, IL.
as TMAZ 81 ethylene oxide derivative of a sorbitol ester which is commercially
available BASF
of Parsippany, New Jersey.
4' MACOL OP-10 ethoxylated alkylphenol, which is commercially available from
BASF of
Parsippany, New Jersey .
°e PolarTherm~ PT 1fi0 boron nitride powder particles, which are
commercially available from
Advanced Ceramics Corporation of Lakewood, OH.
as EMERY~ 6717 partially amidated polyethylene imine which is commercially
available from
Henkel Corporation of Kankakee, IL.
s° A-174 gamma-methacryloxypropyltrimethoxysilane which is commercially
available from
OSi Specialties, Inc. ofTarrytown, NY.
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couplin a ents,
boron nitride particles 5.7 5.5 5.6
in
aqueous sus ension52
antifoamin a ent53 0.2 0.2 0.2
styrene/ acrylic copolymer35.2 33.7 35.3
hollow article dis ersion
sa
a oxidized linseed oilss 7.3 10.5 0
a oxidized so bean oil5g 0 0 7.3
wei ht ercent solids 3.4 3.5 3.4
LOp ~. _ 0.39 0.30
0.42
-. T
Each of the aqueous size compositions of Table 3 were use to coat
glass fibers forming G-75 E-glass fiber strands. Each coated glass fiber
strand was dried, twisted to form a yarn, and wound onto bobbins in a
similar manner using conventional twisting equipment.
The yarn of Sample D was evaluated by comparing the coated yarn
to yarn coated with a sizing composition similar to Sample D but without
the epoxidized linseed oil (hereinafter "Comparative Sample 1 "). This
comparison included visual inspection of the appearance of a 7628 style
fabric woven on an air jet loom. The woven fabric used Sample D as the
fill yarn a twisted G-75 E-glass fiber strand with fiber coated with a
different
resin compatible sizing compositions' as the warp yarn. It was observed that
fabric woven with yarn coated with Sample D exhibited less loose fuzz on
5' A-187 gamma-glycidoxypropyltrimethoxysilane which is commercially available
from OSi
Specialties, Inc. of Tarrytown, NY.
52 ORPAC BORON NITRIDE RELEASECOAT-CONC boron nitride dispersion which is
dispersion of about 25 weight percent boron nitride particles in water
commercially available
from ZYP Coatings, Inc. of Oak Ridge, TN.
s3 MAZU DF-136 antifoaming agent which is commercially available from BASF
Company of
Parsippany, New Jersey.
54 ROPAQUE~ OP-96, 0.55 micron particle dispersion which is commercially
available from
Rohm and Haas Company of Philadelphia, PA.
55 FLEXOL LOE epoxidized linseed oil commercially available from Union Carbide
of Danbury,
Connecticut.
~ FLEXOL EPO eooxidized soybean oil commercially available from Union Carbide
of
Danburv. Connecticut.
5' The warp yarn was PPG Industries, Inc.'s commercially available fiber glass
yarn product
designated as G-75 glass fiber yarn coated with PPG Industries, Inc.'s 1383
binder.
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the fabric as well as less collected fuzz at contact points on the loom,
especially at the yarn accumulator, when compared to fabric woven with
yarn coated with Comparative Sample 1. No fabric was woven using yarn
incorporating fibers coated with Samples E or F because of the high initial
amount of fuzz observed on the loom. It is believed that this condition
was the result of an LOi level lower than required to prevent excess fuzz
formation. In the present invention, it is anticipated that an LOI of at least
0.40 for the sizing compositions discussed above is required to reduce
fuzz formation during weaving.
EXAMPLE 3
The yarns of Samples A, B and C and a Comparative Sample 258 (yarn
coated with a starchloil sizing) were evaluated for several physical
properties,
such as loss on ignition (LOI), air jet compatibility (Air Drag) and Friction
Force. The results are shown in Table 4.
The loss on ignition (weight percent of solids of the forming size
composition divided by the total weight of the glass and dried forming size
composition) of each Sample is set forth in Table 4.
Each yarn was evaluated for Air Drag Force or tension by feeding the
yarn at a controlled feed rate of 274 meters (300 yards) per minute through a
checkline tension meter, which applied a tension to the yarn, and a Ruti two
millimeter diameter air nozzle at an air pressure of 138 kPa (20 pounds per
square inch).
The Samples and Comparative Sample 2 were also evaluated for
Friction Force by applying a tension of about 20 grams to each yarn sample
as the sample is pulled at a rate of 274 meters (300 yards) per minute
through a pair of conventional tension measurement devices having a
se The yarn was PPG Industries, Inc.'s commercially available fiber glass yarn
designated as
G-75 glass fiber yarn coated with PPG Industries, Inc.'s 695 starch/oil
binder.
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stationary chrome post of about 5 centimeters (2 inches) diameter mounted
therebetween to displace the yarn about 5 centimeters from a straight line
path between the tension measurement devices. The difference in force in
grams is set forth in Table 7 below. The Friction Force test is intended to
simulate the frictional forces to which the yarn is subjected during weaving
operations.
During testing, Samples B and 2 were tested at the same time as a
first quantity of glass fiber yarn coated with sizing composition Sample A
(hereinafter designated as Sample A3) and Sample C was tested at the
same time as a second quantity of glass fiber yarn coated with sizing
composition Sample A (hereinafter designated as Sample A4). Samples
A3, A4 and B were about 2.8 weight percent solids. Sample C was about
3.1 weight percent solid. Comparative Sample 2 was about 5.9 weight
percent solid.
Table 4
Sample
~
A3 B 2 A4 C
LOI (wei ht percent)0.42 0.49 1.11 0.38 0.37
Air Drag (grams) 56.2 51.2 52.9 58.8 53.2
Friction force (grams)53.6 61.5 95.1 48.8 68.9
From Table 4, it can be seen that sizing Samples A, B and C have an
air drag comparable to that of Comparative Sample 2 (starch/oil binder).
Furthermore, the lower friction force in Samples A, B and C indicates that the
yarn is more easily removed from the loom accumulator during weaving when
compared to Comparative Sample 1.
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EXAMPLE 4
The yarns of Samples A, B and C and Comparative Sample 2 were
evaluated for Air Drag in a similar manner to Example 3 above, except that
the Air Drag values were determined for a bobbin sample at the pressures
indicated in Table 5. Each yarn also was evaluated for average number of
broken filaments per 1200 meters of yarn at 200 meters per minute using a
Shirley Model No. 84 041 L broken filament detector, which is commercially
available from SDL International Inc. of England (shown in Table 5 as Test 1).
The broken filament values are reported from sections taken from a full
bobbin, the same bobbin after removing 227 grams (0.5 pounds) and the
same bobbin after removing 4540 grams (10 pounds) of yarn. Each yarn was
further evaluated for the number of broken filaments at increasing levels of
tension and abrasion (shown in Table 5 as Test 2). In Test 2, a sample of
yarn was unwound from a bobbin at 200 meters/minute, threaded in a
serpentine manner through a series of 8 ceramic pins on a uniform tension
control device (sometimes refered to as a gate tensioning device), and
passedthrough the Shirley broken filament detector (discussed above) to
count the number of broken filaments. The spacing of the pins on the
tensioning device was varied using different dial settings to provide various
levels of tension in the yarn. This particular test used a Model UTC-2003
tensioning device commercially available from Steel Heddle Co. of South
Carolina. The broken filaments was reported in number of broken filaments
per meter of yarn.
The results of these tests for Samples A, B and C and Comparative
Sample 2 are set forth in Table 5 below. In a manner similar to that
discussed above in Example 3, Samples B and 2 were tested at the same
time as a first quantity of glass fiber yarn coated with sizing composition
Sample A (hereinafter designated as Sample A5) and at a latter date Sample
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C was tested at the same time as a second quantity of glass fiber yarn coated
with sizing composition Sample A (hereinafter designated as Sample A6).
TABLE 5
Sample
A5 B 2 A6 C
A1R DRAG ( rams)
15 psi 46.10 42.50 42.23 47.47 42.33
20 psi 56.20 51.20 52.94 58.84 53.18
25 psi 67.33 60.30 64.13 69.45 67.66
30 psi 77.34 70.84 75.74 75.29 77.63
35 psi 89.42 89.96 85.96 83.70 82.74
40 psi 104.97 101.21 98.48 87.23 92.18
45 psi 113.41 107.74 110.34 99.91 102.91
TEST 1
full bobbin 0.170 0.882 0.032 1.735 0.066
227 grams 0.160 0.648 0.041 0.904 0.075
(0.5 pound)
4540 grams 0.098 1.348 0.008 0.518 0.022
(10 pounds)
TEST 2
Setting 2 0.683 5.017 0.119 0.372 0.011
Settin 3 0.753 4.772 0.083 0.450 0.017
Setting 4 0.713 3.753 0.147 0.367 0.017
Setting 5 1.267 4.025 0.150 0.811 0.061
Setting 6 1.608 8.383 0.322 0.286 0.044
Settin 7 4.128 6.517 0.611 0.403 0.058
Setting 8 4.472 14.800 0.978 0.406 0.128
As can be seen in Table 5, sizing Samples A, B and C have an air drag
comparable to that of Comparative Sample 2 (starch/oil binder).
From the foregoing description, it can be seen that the present
invention provides glass fiber strands having an abrasion-resistant coating
which provide good thermal stability, low corrosion and reactivity in the
presence of high humidity, reactive acids and alkalies and compatibility with
a
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variety of polymeric matrix materials. These strands can be twisted or
chopped, formed into a roving, chopped mat or continuous strand mat or
woven or knitted into a fabric for use in a wide variety of applications, such
as
reinforcements for composites such as printed circuit boards.
It will be appreciated by those skilled in the art that changes could be
made to the embodiments described above without departing from the broad
inventive concept thereof. It is understood, therefore, that this invention is
not limited to the particular embodiments disclosed, but it is intended to
cover
modifications that are within the spirit and scope of the invention, as
defined
by the appended claims.
