Note: Descriptions are shown in the official language in which they were submitted.
~ro 9412s272 216;~ 3 ~ PCT/USg4/04679
DIMENSIONALLY STABLE REINFORCED THERMOPLASTIC
PVC ARTICLES
Field of The Invention
This invention relates to composite articles cont~ining flexible fiber reinforced
5 polyvinyl chloride.
Bac k~round of the Art
European patent publication 411 429 published 2-6-91 discloses articles made from high
molecular weight polyvinyl chloride, plasticizer, and reinforcement material. The
reinforcement material is selected from particulate or fibrous materials. The polyvinyl
10 chloride has a molecular weight in terms of inherent viscosity above 1.0 preferably 1.4
to 1.7. This material is designed to sustain low continuous load and exhibit little or no
deflection at high telllpelal~;s. Particulate reinforcement is not distinguished from
fiber reinforcen ~nt
U.S. patent no. 3,892,692 discloses ethylene vinyl chloride copolymers which are15 plasticized and exhibit improved plasticizer p ~ -ce. The copolymers contain a
modulus index of less than 3000 psi as colll~ed with rigid polyvinyl chloride having a
modulus of 300,000 psi. Any type of reinforcing fillers can be used among those
suggested are clay, iron oxide, calcium carbonate, asbestos, glass, rayon, and mineral
wool. This patent does not acknowledge that non-fibrous reinforcement behaves
differently with respect to llim~n~ional stability when combined in a plasticized, flexible
matrix, as co~llpared to fibrous reinfolcel-.ent
Plasticized polyvinyl chloride has been exploited as a useful tough, weatherablematerial. US-A-3 084 078 is a general disclosure of phth~l~t~ ester, a widely used
plasticizer. US-A-2 535 643 discloses a class of plasticizers and any usual commercial
PVC (see column 3, lines 20-22). US-A-3 796 681 is directed to plastisols.
EP-A-0 057 470 broadly shows non-reinforced plasticized PVC.
21~1330
WO 94125272 PCT/US94/04679
The fiber reinforcing of rigid thermoplastics has been commercially exploited instructural uses to provide for rigidity (modulus enhancement) beyond that obtainable
from the rigid thermoplastic matrix alone. Chopped glass fibers having a diameter from
about 10 microns to about 25 microns have been commerciall~ developed specifically
S for this purpose. The addition of glass fibers to a rigid thermoplastic matrix resin
reduces the coefficient of linear thermal expansion (CLTE) of the composite. There are
practical upper limits on the amount of glass fiber content usable with PVC, hence
limits on the extent of reduction in CLTE using glass fibers alone with PVC.
There has been observed an inverse relationship between CLTE of the fiber reinforced
10 composite and the tensile modulus of the thermoplastic matrix of the composite. That
is, when one Co~ J~eS the coefficient of linear thermal expansion of two different glass
fiber reinforced thermoplastics, the matrix which has the lower modulus will exhibit a
relatively higher CLTE for the reinforced composite.
In some end use applications for non-structural thermoplastic polymers, the high tensile
15 or flexural modulus is not nPedPrl, however due to poor ~iim~n~ional stability, the
decigner often is of the belief that high modulus is needed to prevent distortions in the
article. The present invention is contrasted with conventional approaches suggesting
high structural strength. The composites of the present invention contain a non-structural colllpollent which has low modulus and strength however, this component
20 possesses an improved degree of dimensional stability, thereby avoiding the build-up of
load stress under çh~nging environmental conditions of exterior applications. The high
~limen~ional stability of the non-structural colnpollent in this invention, over a broad
tclllpcl~ re range, is sufficient to enable close tolerance fit with the structural
component without distortion of the non-structural component. When fibers are present
25 in a viscous thermoplastic melt undergoes, during processing there is fiber orientation
along shear force lines, this may result in non-uniform CLTE throughout the article,
possibly resulting in later distortion. It is desirable to achieve a less random orientation
of fiber reinforcement in the thermoplastic matrix in order to obtain the lowest CLTEin
one direction, especially for elongated articles having high aspect ratio.
,VO 94/25272 21~ ) PCT/US94/04679
- 3 -
SummarV of the Invention
In accordance with the invention there is provided a composite of a reinforced,
plasticized polyvinyl halide composition (A) integrally bonded to a structural member
(B) by mechanical or adhesive f~ctening means. The structural component (A) is
selected from the group concisting of metal sheet, shaped metal articles, rigid
thermoplastic, and rigid thermoset articles. The composite optionally and preferably
further comprises an apl)edldllce (C) layer overlying (A) on the surface not cont~cting
(B). The appedldllce layer (C) can completely surround (A) or cover only the show
side with a small portion e~t.?n~ling around the edge of the show side so as to provide a
area for ~ .ing (C) which is not seen. Preferably (C) comprises a thermoplastic
compound such as non-reinforced, pigm~nt~d plasticized polyvinyl halide composition,
decorative paint and the like. The structural component (B)is generally selected from
the group consicting of a rigid molded, stamped or shaped metal article such as a steel,
all-minl-m or thermoset polymer article, a metal door, a metal door casing, a window
pane, and a metal window casing, to name a few examples. The structural component
(B) can be coated or non-coated for example in a painted automotive body panel, a
RIM molded thermoset polymeric article in the shape of a bumper. Co,llpolle.lt (A) is
most advantageously formed in the shape of an auto body side molding, weather seal
profile, cove trim piece for pools and auto bulnpel fascia, to name a few examples.
Component (A) is a non structural col.lponellt and does not have the capability to
sustain stress loading. Structural component (B) must be joined with (A).
Compol1elll (A) comprises: a PVC miscible plasticizer, polyvinyl chloride
homopolymer resin, and fibers. The polyvinyl chloride exhibits a preferred intrinsic
viscosity measured according to ASTM D1243 of from 0.4 to 0.9. Molecular weightsin terms of inherent viscosity of between 0.5 and 0.7 exhibit the best combination of
melt strength and flowability. The preferred (A) component has poorer sag strength
than materials taught in EP 411 429, and is not as useful for structural strength.
Plasticizer is present at a level of from about 15 weight parts to about 150 weight parts
per 100 weight parts polyvinyl halide resin in (A). Plasticizer is preferably present in
(A) at from 20 weight parts to 55 weight parts per 100 weight parts polyvinyl halide in
WO 94/25272 21613 ~ o PCT/US94/04679
- 4 -
(A). Fibrous reinforcing material can be selected from the group consisting of chopped
glass fibers and polymeric fibers, such as~aramid, polyarnide, polymethacrylate, fibrous
derivatives of cellulose non-glass fibers are usable but less preferred for economic and
technical reasons. In addition to plasticizer component (A) can further contain a
5 flexible polymeric material, for example, EVA, SBR, NBR, MBS, acrylic rubber, ABS,
urethane, copolyester, styrenic block rubbers, any of which may or may not be
completely miscible with PVC.
Component (A) exhibits among the lowest coefficient of linear thermal expansion per
ASTM D696 of any material useful for molding of shaped plastics when sufficient
amounts of plasticizer are used. Generally at least 15 weight parts per 100 weight parts
PVC is required in (A). The plasticiæd PVC polymer will have a PVC phase having
glass transition t~ e of less than 50C. The plasticized PVC matrix has reduced
tensile modulus measured per ASTM D638 co",p~ued with rigid fiber reinforced
materials. However, because component (A) is joined with a structural component (B),
15 the strength and rigidity are not required in (A). The plasticized, reinforced material
exhibits significantly better ~limen~ional stability as shown by CLTE and overcomes the
lack of structural strength.
The amount of glass fibers generally can range from 3% to 50% by weight fiber
reinforcement material. Dimensionally stability is further improved along with a20 balance of good prope,lies when the glass fibers are present at from 10 to 30 percent by
weight. The plefcl,ed chopped glass fibers have a diameter of from about 8 to 25microns and length of from 1 to 25 rnm prior to combining with the thermoplastic.
Upon inco",o,alion into PVC, the glass fibers are broken leaving a variety of fiber
lengths. Preferred glass fibers dimensions and 10-13~1m by 3-6 mm. Optional
25 particulate or platelet reinforcement material can also be combined with or can displace
a quantity of fiber reinforcement and results in a non-structural material having CLTE
of 4x10-5 K-' or less and a good combination of physical plopcllies. The articles are
shaped according to the forming method employed and exhibit a tensile modulus below
that of reinforced rigid therrnoplastic PVC, that is a modulus of from about 0.1 Gpa to
30 about 0.5 Gpa. The coefficient of linear thermal expansion for the preferred
,VO 94/25272 21 ~ 13 ~ Q PCT/US94/04679
embodiments, per ASTM D696, is measured from -30C to +30 C and is found to
preferredly lie in a range of from about O.lx10-5 K-' to 4xlO-s K-', more preferably
from l.Ox10-5 K-' to 2.9x10-5 K-', and still more preferably from l.Ox10-5 K-' to
2.0x10-5 K-'.
S In accordance with the invention there is provided a composite comprising an extruded
non-structural component (A) as above which exhibits a coefficient of linear thermal
expansion of from O.lxlO-s K-' to 4x10-5 K-'. (A) is prepared by subjecting the (A)
compound to an extrusion process whereby a shaped profile is formed which conforms
to the cross-section of the extruder die. The prefe.led extruded non-structural articles
10 are elongated and have an aspect ratio of length to width of at least 2, preferably 4,
more preferably about 6 to 50 or more. The fiber orientation provides an improved
CLTE in the axial direction, and the magnitude of lineal expansion is desirably very
low.
In accordance with the invention there is provided a composite article co~ g non-
15 structural conlponen~ (A) formed by injection molding process. The article has
excellent ~limPn~ional stability. Using the method of injection molding, the compound
is formulated for high melt flowability and the molten material co"~ glass fibers
adequately flows to fill the entire void in the mold. The non-structural co~ ,ollent (A)
exhibits excellent rlim~n~ional stability and can be used in contact with rigid structural
20 articles with tight size tolerance, without causing a distortion in the weaker component
(A).
21~1330
WO 94125272 PCT/US94/04679
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a log-log plot of tensile modulus (GPa) on the x-axis versus coefficient of
linear thermal expansion ( X 10-5 K-' ) (CLTE) for a variety of materials. The
triangular data points include metals, and rigid, fiber reinforced thermoplastics, as well
S as rigid non-reinforced thermoplastics. The circular data points are measurements made
from examples of the method of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The triangular data points in Figure 1 illustrate a plot of CLTE versus tensile modulus
for a variety of materials. The symbols used lepl~,selll the following:
CLTE (X10-5 K)
P-PVC - plasticized particulate
reinforced polyvinyl chloride 36
LDPE - low density non-reinforced
polyethylene 1 8
HDPE - high density non-reinforced
polyethylene 12
PP - non-reinforced polypropylene 11.2
PS - non-reinforced polystyrene 7.2
PC - non-reinforced polycarl,on~e 7.0
u-PVC - particulate reinforced,
non-plasticized rigid polyvinyl chloride 6.3
m~gn~cium 2.6
al~ . 1.8
brass 1.8
copper 1.7
stainless steel 1.6
carbon steel 1.2
The table above illustrates that non-reinforced thermoplastic polymers or particulate
reinforced thermoplastic exhibit higher coefficient of linear thermal expansion and
30 relatively lower tensile modulus compared to a like polymer cont~ining glass
reinforcement. None of the thermoplastic materials represented by triangles, whether
fiber reinforced or not, exhibit a CLTE as close to metals aluminum (Al) magnesium
(Mg), brass, Copper (Cu), 316 stainless steel (SS) and carbon steel (steel). They vary
~O 94125272 2 1 6 1 3 3 ~ pcTrus94lo4679
-7-
by at least a factor of two, and in many instances by a factor of 7 or more. As the
graph depicts, comparing PP to GFPP, as expected, glass fibers increase the tensile
modulus and reduce CLTE. With respect to PVC and GFPVC, the same effect is
noted.
5 The trend in the triangular data points of figure 1 suggests that the tensile modulus of
the matrix material and the CLTE of fiber reinforced versions are inversely
proportional. The lower CLTE of examples A- K for glass reinforced, plasticized PVC
does not follow the observed trend in that with a higher proportion of plasticizer there
is the expected reduction in modulus, however CLTE is decreased. Reduction of
10 CLTE to this extent is hllpol~lt since these levels of CLTE are very near or can be
made equal to that of ~ imil~r structural materials. Because the non-structural
compo~ (A) has no structural strength and cannot sustain load stress, the material
would easily distort, however due to the excellent ~lim~n~ional stability, no distortion is
observed. Also there is no distortion over a wide t~lllpel~ re range making these
15 articles highly desired for exterior decorative trim for automobiles. The composite
Col~t~ g non-structural colllponent (A) can have a close match of the CLTE of the
structural component (B) to which it is ~tt~chç(l As explained previously, non-
structural uses are uses where an article does not bear sustained load stress. Sufficient
intemal stresses would lead to pçrm~n.ont distortion or creep for the non-structural
20 component (A) if it were not for the excellent iimPn~ional stability. In many
applications the non-structural colllpollent(A) can be tightly attached to the structural
component (B) and m~int~in adherence over a wide temperature range and under
prolonged themmal cycling without we~kening or colllplolllising the att~chment means.
Conventional methods for attaching the non-structural component (A) to structural
25 component (B) can be used. These include the use of adhesives such as acrylicpressure sensitive adhesives, adhesive coated foam tapes, urethane adhesives, epoxy
adhesives, and hot melt adhesives all of which are in commercial use. Mechanicalfasteners or rivetting can be used. Themmal bonding or dielectric heating could be used
also, these methods being known and available methods beyond the scope of the
30 invention.
WO 94t25272 21613 ~ O PCT/US94/04679
The plasticized matrix material must exhibit a dominant PVC phase morphology.
Those materials which reduce the modulus`m a blend with PVC but which are
immiscible with PVC are less preferred in the present invention. A combination of
PVC miscible plasticizer and non-miscible polymer is however useful. Miscibilit
5 herein means that the plasticized matrix must exhibit a Tg which is lower that of a rigid
matrix PVC. The matrix may also include lubricants processing aids and at least one
stabilizer for PVC. Impact modifiers are not generally required but may be used.
The plotted data point for example A in figure 1 reples~ s the measured l)ropc.lies
obtained by combining 35 weight parts of plasticizer with polyvinyl chloride (100 wt.
parts) having an inherent viscosity of 0.68. The CLTE of example A was 3.1 x10-5 K-
' and is lower than rigid unplasticized PVC shown in figure 1 having a CLTE of 3.2
x105 K-~. The modulus of example A was 1.4 GPa versus S.l GPa for rigid, glass
reinforced, unplasticized PVC.
Example B plotted in figure 1 resulted from the combination of 100 wt. parts PVC(I.V. 0.52) with 10 parts of polyacrylate proces~ing aid and 35 parts of mixed alkyl (C,-
Cg-C~,) phth~l~te plasticizer, stabilizer, lubricants, and an amount of 0.25 x 13 micron
glass fibers siæd with aminosilane coupling agent such that the total composition
contained 30% by weight of glass fibers. As figure 1 shows the modulus of example B
has been reduced below that of rigid GFPVC but is higher than example A; and the20 CLTE is also favorably identical to the CLTE of al-.,.,i..--,.~ Al~lminlnn can be used as
a substrate for this article over a broad te~ .dlllre range.
Example C represents the combination of 52 weight parts of plasticizer in a compound
similar to example B, but having glass fiber content of 20% by weight. There is noted
a still further reduction in CLTE versus example B due to the additional plasticizer
25 even though the amount of glass content is 20% by weight in C versus 30% by weight
in B. The modulus of C is reduced from 1.9 GPa to 0.79 GPa, yet the m~gnit~l(le of
tensile modulus is not of primary concern for the aforementioned uses. Example Dcontains a still lower CLTE than example C yet has a higher tensile modulus as C and
for some uses this a more desirable combination of properties.
VO 94125272 ~1613 3 a PCT/US94/04679
g
In table 1 below are listed the weight percent glass fiber content and parts plasticizer
per 100 weight parts PVC resin for the examples A-K plotted in figure 1.
TABLE I
EXAMPLE CLTE TENSILE % GLASS WT.PARTS
(x10-5 MODULUS CONTENT PLASTICIZER
K ') (GPa)
E 2.0 0.18 10% 74
G 1.8 0.11 10% 82
Exd", ~ 'e s E and G have a CLTE below GFPVC. As can be seen from the data above10 that i"c,easi"g the level of p~ lici er from 74 to 82 phr at a fixed weight percent glass content
causes a reduction in the coefri~;el,l of linear thermal ex~,ansion.
TABLE 2
EXAMPLE CLTE TENSILE % GLASS WT.PARTS
!x10 5 MODULUS CONTENT PLASTICIZER
OK1) ~
C 2.2 0.79 20% 52
D 2.1 1.2 20% 52
H 1.8 0.50 20% 55
J 1.5 0.43 20% 82
K 1.3 0.21 20% 82
As can seen in table 2 that with 20% glass fiber content and a pl~ ; er content of
either 52 to 82 parts per 100 parts PVC yields reduced CLTE. It can be also seen that the
modulus of the cor"posite is also reduced.
TABLE 3
EXAMPLE CLTE TENSILE % GLASS WT.PARTS
(x10'5 MODULUS CONTENT PLASTICIZER
~ ~ (GPa)
A 3.1 1.4 30% 35
B 2.4 1.9 30% 35
F 1.9 4.9 30% 35
1.7 0.81 30% 52
As table 3 shows, the plasticizer content of 35 or 52 parts per 100 parts PVC yields a
30% glass fiber reinforced PVC composite having a reduced CLTE.
WO 94/25272 216 13 ~ ~ PCT/US94/04679
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,
The above examples each contained polyvinyl chloride homopolymer having an I.V.
ranging from 0.5 to 1.1, a stabilizer such as an organotin or a mixed metal soap type,
such as a barium-zinc stabilizer. Preferred stabilizers are mixed metal types. The
amount of thermal stabilizer used can range from I to 5 weight parts. There can be
5 included other conventional additives such as processing aids, or impact modifiers,
pigments or colorants, UV stabilizers and co-stabilizers known in the compounding art.
Impact modifiers are not generally need because of the inherent toughness of theplasticized matrix. The articles exhibit Izod impact strength of at least 1 ft-lb per inch
of notch. Preferred processing aids are polyacrylates, for example those commercially
10 available from Rohm and Haas, Inc. under the Paraloid trademark. Most preferred
processing aids are styrene-acrylonitrile copolymers. The conventional lubricant waxes,
polyol esters, and fatty soaps can be used. The plefe..ed lubricant is a silicate type, in
which the resulting surface tension of the surface of a shaped article is higher than 35
dynes/cm, preferably 4~ dynes/cm and most preferably from 45 to 65 dynes/cm2 in
15 order provide improved adhesion to coatings or applied films. In-mold transfer of films
during formation is a plefel,~d method of joining one side of the non-structural article
to appearance films such as pigmented non-reinforced flexible PVC films. Amounts of
from 2 to about 15 weight parts of lubricant can be used, with the type and amount of
lubricant and stabilizer depending on factors beyond the scope of this invention.
20 Any of the conventional processes for making PVC polymers such as mass, suspension,
solution or emulsion polymerization methods can be used. Mass and suspension
polymerization methods are the preferred processes. Suspension polymers are mostpreferred. Porous, commercial suspension grade homopolymer PVC having an l.V. offrom 0.4 to 0.85 are preferred with the more preferred PVC polymers having an I.V. of
25 from 0.5 to 0.7. Generally the molecular weight is controlled by the polymerization
temperature and/or by the use of chain transfer agents.
Although the PVC polymer can be a copolymer of vinyl chloride and terminally
unsaturated comonomer(s), it is essenti~l that the PVC resin be a rigid polymer in the
unplasticized state, the p.erclled type of rigid polymers being a homopolymer of30 polyvinyl chloride. In the present invention, homopolymers m~int~in better physical
~O 94/25272 21613 ~ O PCT/US94/04679
I I
properties in the plasticized state such as higher strength and modulus. Homopolymers
or copolymers of PVC having an unplasticized modulus of elasticity of greater than
100,000 pounds per square inch per ASTM-D747 are essential for use in the present
invention. Thus, flexible copolymers of PVC having a Tg in the unplasticized state of
less than about 60 C and having an unplasticized modulus for less than 100,000 p.s.i.
are not suitable in the present invention. Block copolymers of homopolymer PVC may
be suitable, provided there is a major predominant phase of rigid polyvinyl halide
polymer which would meet the above modulus criteria. The use of flexible copolymers
obviates the ability to add sufficient plasticizer to produce the CLTE lowering effect
and therefore are outside the scope of the invention.
The miscible plasticizer forms a single phase, single Tg PVC matrix and is incorporated
at a level of from about 5 weight parts to about 150 weight parts per 100 weight parts
polyvinyl chloride resin, the amount in any embodiment depending on the modulus and
CLTE desired. More preferably, plasticizer is incorporated at 20 weight parts to 65
weight parts per 100 weight parts polyvinyl chloride.
The formulations of the invention must have adequate melt flowability, usually
evaluated by the spiral flow test. Spiral flow is a measure of the extent of injection
melt flow under a fixed ram force input. The extent of spiral flow provides a
prediction of the limitations in size and configuration of injection molding dies suitable
for a given resin compound. The test employs a gr~ te(l 60-inch spiral flow moldwith a standard cross section die such as a 1/8 inch by 3/16 inch rectangular cross
section die used in conjunction with a Van Dorn injection molding m~rhine. Generally,
the mold telnl,e.dlule is set at 55C, the injection melt pressure is a constant psi, with a
constant injection time, clamp time, and mold open time, giving a constant total cycle
time. A screw of specified diameter and L/D is used. Stock tell~e~ re at the nozzle
is standardized also. Spiral flow is proper when the polymer is able to flow into the
pattern of the mold used. The extent of spiral flow varied depending on the molecular
weight of the plasticizer, the molecular weight of the polyvinyl halide polymer as well
as the amount of reinforcement or other material employed. A desirable spiral flow is
at least 15 inches, preferably at least 25 inches, more preferably at least 35 inches, and
most preferably at least 40 inches. Contrary to conventional wisdom, it has been found
2161330
WO 94125272 PCTtUS94/04679
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that relatively low molecular weight polyvinyl chloride having an I.V. of from 0.4 to
0.85 works better in the present invention than PVC having molecular weight of 0.9 or
above. When the molecular weight of polyvinyl chloride is in a range of from O.S to
0.7, there is exhibited the best combination of melt strength and flowability and less
5 plasticizer is required to give the same spiral flow than with the use of high molecular
weight PVC (I.V. above 1.0).
The plasticizers used in this invention are PVC miscible plasticizers to the extent that a
single phase morphology results in combination with PVC. These include those taught
in The Technolo~Y of Plasticizers, Sears and Darby, John Wiley and Sons, New York
(1982) ch.4, incorporated herein by reference. A suitable plasticizer may be polymeric,
or monomeric such as a high Tg solid or a low Tg material but there must be a degree
of miscibility such that a single phase, single Tg results from their combination. The
prefel~ed plasticizers are liquids. The amount of plasticizer employed is the minimum
amount nPces~ry to reduce the CLTE to 4 x10-5 K-' or less. Generally from at least 5
15 weight parts per 100 weight parts PVC (phr) is sufficient to provide a noticeable
reduction in CLTE provided that the fiber content is sufficiently high, such as 10% by
weight or higher. A preferred combination colllains from about 20 to 85 phr
plasticizer. By selecting the amount of flber and plasticizer content the desired
combinations of tensile modulus and CLTE can be obtained.
Examples of suitable polyesters with molecular weight below 10,000, especially those
derived from glutaric or sebacic acid, plasticizers include the phth~l~tes trimellitates,
epoxides, aliphatic diesters, and phosph~tes, including mixtures. Preferred are the
phth~l~tes trimellitates and epoxides. Examples of preferred phth~l~tes include dioctyl
phth~l~te, diisooctyl phth~l~te~ diisodecylphth~l~te; and mixed alkyl esters such as
heptyl, nonyl and undecyl phth~l~te. Preferred trimellitates are tri-octyl trimellitate and
tri-isononyl trimellitate. The preferred epoxides include epoxidized soybean oil, and
epoxidized linseed oil. As used in the present invention, a single plasticizer can be
employed, as well as blends of more than one miscible plasticizer. An example of a
preferred blend is a blend of 85 parts per hundred parts resin of dioctyl phth~l~te and 5
parts per hundred parts resin of epoxidized soybean oil.
VO 94125272 21613 3 0 PCT/US94/04679
- 13 -
The amount of fiber reinforcement used ranges from about 3 weight percent to about 50
weight percent of the non-structural component (A). Preferably from about 6 weight
percent to about 35 weight percent and more preferably from 10%. The most preferred
amount of fiber reinforcement material present depends on the particular combination of
5 ploy~lies desired as these properties can be accurately tailored to suit the requirements.
Examples of suitable fiber reinforcement materials include the various glass fiber types,
such as E-glass, with or without coupling agents incorporated thereon, either as mats,
woven or non woven fibers or chopped; stainless steel shavings; polymeric fibers, such
as aramid or cellulosic fibers, and combinations of more than one type of fiber. The
10 preferred fiber reinforcing material has a diameter of greater than or equal to 8 microns,
preferably 10 to 13 microns, more preferably at least 12 microns and most preferably
about 13 microns, and a length of 1/8" (3 mm) or 1/4" (6 mm). Alternatively, a
particular or platelet filler, or both can be included. An example is the combination of
glass and mineral filler, the mineral filler being either of spherical or platelet shape. A
15 particulate filler such as calcium carbonate and platelet reinforcement fillers such as
mica or talc are exemplary types. Plefel..,d combinations of fiber and platelet
reinforcing filler are 30% fiber and 10% platelet, and 20% fiber and 20% platelet, each
respectively.
The glass used in this invention can be sized or non-sized. A preferred sizing and
coupling agent are disclosed in U.S. Patent 4,536,360 to Rahrig, incorporated herein by
reference which describes the use of aminosilane coupling incolyold~ed into a sizing
Co~ g a film former which is more basic than polyvinyl acetate. Preferred film
formers are polyethers, and silylated polyazamides. Higher physical properties are seen
when fii~minQsilane and preferred film formers are present on the glass fibers.
To prepare component (A) it is preferred to first mix plasticizer with the polyvinyl
chloride resin in the initial compounding step. Fiber reinforcement material is added
subsequently. As a result of the mixing, the reinforcement material, whether initially in
WO 941252~1 6 13 3 0 PCT/US94/04679
- 14 -
long glass fibers or not, will be crushed and broken, and will be dispersed relatively
uniformly throughout the mixture. A specific method of prep~lion of the composite
comprises combining PVC, process aid, plasticizer, stabilizer, filler or pigment, if used,
and lubricants in a Henschel mixer. The powder mixture can be fluxed under heat and
S shear in a Buss reciprocating extruder. Is preferred to equip the extruder with a hopper
and feeding screw through which the glass fibers are added. The polymer compoundand glass lllixlul~ is then sheared to uniformly disperse the glass throughout the melt.
The mixture can be formed into pellets and later molded, extruded, and shaped in any
conventional process for forming shaped thermoplastic articles.
10 The alternative would be to combine the process by directly making the melt mixture
and shaping directly into the final product. No special precautions are needed to
employ con~le.cial PVC extrusion or injection molding processes.
The articles will generally be formed at tel,lpc~ res high enough to induce melt flow
under pl~S~ule. The telllpela~ ;s and work level employed are high enough to fuse the
15 resin particles and ensure complete plasticization of the matrix. The pressule should be
high enough to extrude an article, or inject the molten composition into a mold pattern,
co-extrude a composite article, or co-inject the material with another thermoplastic
component such as a ~liccimil7~t plastic substrate. Typically such temperatures range
from about 175C to about 235C, and preferably from about 180C to about 210C.20 The pressures are generally those encountered in injection molding and extrusion, co-
extrusion, co-injection or l~min~ting processes. The composition is also useful in
compression molding, although this process is not favored as a commercial process.
Examples L- M
The following Examples were prepared to illustrate that both glass fibers and talc can
25 be combined in the method at up to 40% and 50% by weight, and enable achieving the
advantages of low CLTE in addition to good physical prol)ellies. The following
components were combined by batch mixing in a henschel mixer, followed by force
vO 94125272 2 1 613 ~ ~ PCT/US94/04679
feeding to a reciprocating single screw extruder equipped with a down-stream port for
incorporating glass fibers.
Example - Parts by Weight
L M
Suspension PVC (I.V. 1.0) 100
Suspension PVC (I.V. 0.68) - 100
Acrylic process aid 10 10
Mixed (C7-C9-C") Phth~l~tec 50 50
Lubricants 4.4 4.4
Ba-Zn Stabilizer 3 3
Pigment 0.1 0.1
Talc* 30% 20%
* amount based of batch weight
Amounts glass were introduced through the port such that the following weight
15 p~,lcellls as obtained:
Examples- weight %
L M
Chopped glass 10 20
Injection molded test plaques were prepared and the following physical ~.ol~e.lies were
measured:
F.Y~-mrles
L M
Tensile Mod. (psi) 128,000 203,000
Tensile Strength (psi) 2,950 3,800
Tensile Elong (%) 22 5
Notched Izod (ft.-lb./in.) 1.7 1.9
CLTE xlO-s K-' (-30 to +30C)* 2.6 1.8
Spiral Flow, (inches.)/cm. 19.3/49 31.5/34.2
* ASTM D696
WO 94/25272 21613 3 PCT/US94/04679
- 16 -
From the above data for L and M it can be seen that injection molded samples exhibit a
desirable combination, stress/strain, impact strength, and CLTE below that obtainable
without the use of a PVC miscible plasticizer. The modulus is not indicative of
rigidity, however it is understood that the method of use is for non-structural
5 application. The desired propc,Lies are CLTE of less than 2.9XI0-4 K-~, and impact
strength of greater than 1 ft.-lb./inch of notch which is improved as compared to a rigid
PVC reinforced composite absent a significant amount of conventional impact modifier.
