Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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REINFORCING MAT FOR A PULTRUDED PART
Field of the Invention
The present invention relates to a method of making a pultruded part
with a novel reinforcing mat.
Background of the Invention
Pultr-usion is a known technique in which longitudinally continuous
fibrous elements, which can include reinforcing fiber and/or a mat, are
combined into
a resin-based structure. The process generally involves pulling reinforcing
fibers
and/or reinforcing mats through a bath of thermoset resin and then into a
heated
forming die. The heat of the die cures the resin as the part is pulled through
the die
on a continuous basis.
The mat and reinforcing fiber are typically flexible and conformable
textile products since they need to conform'to the profile of the die. The mat
and
reinforcing fiber are typically glass products, while the resin matrix is
usually, but not
necessarily, a thermosetting polyester. Mat material is generally in the form
of a non-
woven, felt-like web having glass fibers randomly placed in a planar swirl
pattern.
During the pultrusion process, reinforcing fibers typically referred to as
rovings comprise groupings of hundreds or thousands of microns-diameter
filaments,
that mechanically behave like flexible rope. The filaments are flexible
because the
diameter of each filament is so small. The flexibility of the individual
filaments
imparts sufficient flexibility to the reinforcing fibers to fulfill the
processing
requirements of pultrusion. In a pultrusion profile, the mat and rovings
constitute the
reinforcement, while the resin constitutes the binder of the solid composite.
After
pultrusion, the rovings are held together by the cured or semi-cured resin
matrix,
providing the pultruded part with rigidity.
The longitudinal strength of pultruded parts is very high since the
majority of the fibers are the longitudinally extending reinforcing fibers
that are
pulled through the die. However, the transverse strength of pultruded parts is
generally minimal because conventional mat fibers extend in random directions
and
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only a small proportion of the total fiber component extends in the transverse
direction.
Conventional mats also have a number of problems that interfere with
the efficiencies of the pultrusion process. First, the mat is relatively
expensive.
Second, the mat is difficult to form into the required shape for complex
parts. The
compressed thickness of the mat also represents a lower limit on the thickness
of
sidewalls, increasing the amount of resin needed for a given part. Lightweight
continuous filament or "swirl" mats are easier to shape, but provide minimal
strength,
and are more prone to ripping at the die entrance due to low wet tensile
strength. The
choice of mat is, in part, a compromise between the necessity for bending to
shape,
the required strength of the pultruded part, and the pulling strength of the
reinforcing
mat.
U.S. Patent No. 5,005,242 (Vane) reports a reinforcing mat having a
plurality of superimposed layers. Each layer consists of a plurality of uni-
directional
non-woven yarns or threads laid side-by-side. The yarns in at least some of
the
different layers extend in different directions. The layers of reinforcing
material are
stitched together by knitting so as to hold the yarns in fixed position
relative to one
another. The mat disclosed in Vane exhibits strength primarily in the
direction of the
uni-directional yams.
U.S. Patent No. 5,908,689 (Dana et al.) reports a mat adapted to
reinforce a therniosetting matrix material. The mat includes a primary,
supporting
layer having a plurality of randomly oriented essentially continuous glass
fiber
strands. The primary layer is about 1 to about 20 weight percent of the mat on
a total
solids basis. A secondary layer is positioned upon and supported by a surface
of the
primary layer. The secondary layer includes a plurality of glass fiber strands
having
a mean average length of about 20 to about 125 millimeters. The strands of the
primary layer are entangled with the strands of the secondary layer by
needling the
primary layer and the secondary layer together.
U.S. Patent No. 5,910,458 (Beer et al.) reports a mat adapted to
reinforce a thermosetting matrix material. The mat includes a primary layer of
generally parallel, essentially continuous glass fiber strands oriented
generally
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parallel to a longitudinal axis of the mat. The primary layer is about 45 to
about 90
weight percent of the mat on a total solids basis. A secondary layer includes
a
plurality of randomly oriented, generally continuous glass fiber strands. The
strands
of the primary layer are entangled with the strands of the secondaiy layer by
needling.
U.S. Patent 4,058,581 (Park) reports adding discontinuous fibers to the
resin bath. Similarly, United States Patent 5,324,377 (Davies) reports mixing
cut
fibers in the resin bath to form a homogeneous mass of resin and fibers. The
continuous fibers, the cut fibers and the resin are then passed through a die
and
become integrated into a pultruded part.
In order for the reinforcing mat to pass through the die with the
longitudinal fibers, it is necessary for the mat to have a sufficient
longitudinal
strength so that it does not tear as it is pulled through the die.
Furthermore, the mat
must have a sufficient shear strength so that it does not twist or skew
allowing one
side edge of the mat to move in advance of the other side edge. If such
twisting or
skewing occurs, the mat will become distorted in the part and the mat
eventually will
break down and the part will be unusable.
Brief Summary of the Invention
The present invention is directed to a reinforcing structure adapted for
use in the manufacture of a pultruded part where the reinforcing structure is
pulled
through a pultrusion die in a continuous longitudinal pull direction. The
reinforcing structure comprises a permeable transport web of staple fibers and
a
plurality of first reinforcing fibers attached to the permeable transport web.
The
portion of the first reinforcing fibers extending in a transverse direction
comprises at
least 40% of a volume of materials comprising the reinforcing structure.
The staple fibers are preferably about 0.01 inch to about 12 inches
long. The staple fibers preferably comprise a weight of about 10 grams per
square
meter to about 1200 grams per square meter before attachment to the first
reinforcing
fibers.
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In one embodiment, the permeable transport web comprises heat-
fusible fibers. In another embodiment, the permeable transport web comprises
at
least two different polymeric fibers, each comprising a different glass
transition
temperature. In yet another embodiment, the permeable transport web comprises
a
plurality of first polymeric fibers comprising a first glass transition
temperature and a
plurality of bi-component fiber wherein a first component comprises the first
glass
transition temperature and a second component comprises a second glass
transition
temperature less than the first glass transition temperature. The bi-component
fibers
can optionally be a core-sheath configuration.
In one embodiment, the permeable transport web comprises a plurality
of fibers at least a portion of which are randomly entangled with the first
reinforcing
fibers. In another embodiment, the permeable transport web comprises a
plurality of
fibers at least a portion of which are thermally bonded to the first
reinforcing fibers.
In yet another embodiment, the first reinforcing fibers are spaced apart and
attached
together by a continuous stitching fiber. In still another embodiment, a
binder
attaches the permeable transport web to the first reinforcing fibers.
The reinforcing structure preferably includes a plurality of perforations
through the peimeable transport web and extending between the first
reinforcing
fibers. The reinforcing structure preferably has a thickness of about 0.004
inches to
about 0.020 inches. The first reinforcing fibers comprise glass fibers,
natural fibers,
carbon fibers, metal fibers, ceramic fibers, synthetic or polymeric fibers,
composite
fibers (including one or more components of glass, natural materials, metal,
ceramic,
carbon, and/or synthetics components), or a combination thereof.
In one embodiment, the transverse direction comprises a direction
about 90 +/- 10 relative to the pull direction. In some embodiments, a
plurality of
permeable transport webs can be used. The reinforcing structure can optionally
include a plurality of second reinforcing fibers extending at one or more
acute angles
relative to the pull direction. In another embodiment, a plurality of second
reinforcing fibers extend at a first acute angle relative to the pull
direction and a
plurality of third reinforcing fibers extend at a second acute angle that is
the negative
of the first acute angle. For example, the reinforcing structure can include
first
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reinforcing fibers oriented at 45 (+/- 15 ) relative to the pull direction
and second
reinforcing fibers oriented at -45 (+/- 15 ) relative to the pull direction.
Alternatively, the
reinforcing structure can include first reinforcing fibers oriented at 60 (+/-
15 ) relative to
the pull direction and second reinforcing fibers oriented at -60 (+/- 15 )
relative to the pull
direction. The ratio of a modulus of elasticity of the reinforcing structure
in the transverse
direction relative to a modulus of elasticity in the pull direction preferably
comprises at least
1.2.
The present reinforcing structure can be prepared by arranging the first
reinforcing
fibers into one or more overlapping layers. In another embodiment, at least a
portion of
fibers in the permeable transport web are thermally bonded and/or stitched to
the first
reinforcing fibers. A binder can also be applied to the permeable transport
web to the first
reinforcing fibers. A plurality of perforations can be formed in the permeable
transport web
and the first reinforcing fibers. A plurality of second reinforcing fibers can
optionally be
arranged at one or more acute angles relative to the pull direction.
The present invention is also directed to a pultruded part made using the
reinforcing
structure. The pultruded part has a cross-section that is uniform along a
longitudinal axis. A
plurality of longitudinal rovings are oriented along the longitudinal axis.
The present
reinforcing structure is arranged along at least a portion of the cross-
section. A resin matrix
substantially surrounds the longitudinal rovings and the reinforcing
structure.
The present invention is also directed to a method of making a pultruded part
using
the reinforcing structure. A plurality of longitudinal rovings are oriented
along the
longitudinal axis of a pultrusion die. The present reinforcing structure is
shaped to generally
conform with at least a portion of the profile of the pultrusion die. A resin
matrix is
combined with the longitudinal rovings and the reinforcing structure in the
pultrusion die so
that the longitudinal rovings and the reinforcing structure are substantially
surrounded by the
resin matrix. The resin matrix is at least partially cured in the pultrusion
die. The pultruded
part is pulled from the pultrusion die.
The present invention is also directed to a method of preparing a reinforcing
structure
for use in the manufacture of a pultruded part, where the reinforcing
structure is pulled
through a pultrusion die in a continuous longitudinal pull direction. The
method includes
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forming a permeable transport web of heat-fusible staple fibers that comprise
a plurality of
first polymeric fibers comprising a first glass transition temperature; and a
plurality of bi-
component fibers wherein a first component comprises the first glass
transition temperature
and a second component comprises a second glass transition temperature less
than the first
glass transition temperature. The permeable transport web is contacted with a
plurality of
first reinforcing fibers that are arranged on the permeable transport web into
one or more
overlapping layers. At least a portion of the heat-fusible staple fibers are
thermally bonded
with the first reinforcing fibers.
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In one embodiment, the reinforcing structure is attached to the
longitudinal rovings prior to combining with the resin matrix. In another
embodiment, a plurality of longitudinal rovings are positioned along each
surface of
the reinforcing structure prior to combining with the resin matrix. Either the
reinforcing structure or the longitudinal rovings can be positioned adjacent
to a
surface of the pultruded part. In one embodiment, alternating layers of
reinforcing
structure and longitudinal rovings are arranged prior to combining with the
resin
matrix.
Brief Description of the Several Views of the Drawing
The invention will now be described in conjunction with the
accompanying drawings in which:
Figure 1 is a schematic, cross-sectional view of a pultruded part in
accordance with the present invention.
Figure lA is an enlarged a portion of the pultruded part shown in
Figure 1.
Figure 2 is a further enlarged schematic detail of the pultruded part
shown in Figures 1 and 1 A.
Figure 2A is a schematic illustration of an alternate pultruded part in
accordance with the present invention.
Figure 3 is a schematic illustration of a pultrusion process and
equipment for carrying out a method of the present invention.
Figure 4 is a schematic illustration of a bottom view of a reinforcing
mat in accordance with the present invention.
Figure 5 is a cross-sectional view of the reinforcing mat of Figure 4.
Figure 6 is a schematic illustration of a top view of an alternate
reinforcing mat in accordance with the present invention.
Figure 7 is a cross-sectional view of the reinforcing mat of Figure 6.
Figure 8 is another cross-sectional view of the reinforcing mat of
Figure 6.
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Figure 9 is a schematic illustration of a method of making a reinforcing
mat in accordance with the present invention.
Figure 10 is a schematic illustration of an entangling device in
accordance with the present invention.
Figure 11 is a schematic illustration of a top view of a web suitable for
making a reinforcing mat in accordance with the present invention.
Figure 12 is a transverse cross-sectional view of the web of Figure 11.
Figure 13 is a longitudinal cross-sectional view of the web of Figure
11.
Figure 14 is another cross-sectional view of the reinforcing mat made
from the web of Figure 11.
Figure 15 is a schematic illustration of a top view of an alternate
reinforcing mat in accordance with the present invention.
Figure 16 is a cross-sectional view of the reinforcing mat of Figure 15.
Figure 17 is an enlarged, fragmentary, schematic representation of a
needle apparatus for forming holes through the thickness of a reinforcing mat.
Figure 18 is an enlarged, fragmentaiy view of a representative needle
useful for entangling staple fibers or cut fibers in a reinforcing mat of the
present
invention.
Figure 19 is a schematic illustration of a top view of an alternate
reinforcing mat in accordance with the present invention.
Figure 20 is a cross-sectional view of the reinforcing mat of Figure 19.
Figure 21 is a schematic illustration of a top view of an alternate
reinforcing mat in accordance with the present invention.
Figure 22 is a cross-sectional view of the reinforcing mat of Figure 21.
Figure 23 is a schematic illustration of a top view of an alternate
reinforcing mat in accordance with the present invention.
Figure 24 is a cross-sectional view of the reinforcing mat of Figure 23.
Figure 25 is a schematic illustration of a top view of an alternate
reinforcing mat in accordance with the present invention.
Figure 26 is a cross-sectional view of the reinforcing mat of Figure 25.
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Figure 27 is a schematic illustration of a top view of an alternate
reinforcing mat in accordance with the present invention.
Figure 28 is a cross-sectional view of the reinforcing mat of Figure 25.
Detailed Description of the Invention
Figures 1 and 1A illustrate a pultruded part 10 for a fenestration
product in accordance with the present invention. The part 10 is shown as a
hollow,
closed, pultruded body 12 having uniformly spaced outer wall structure 14, an
inner
wall structure 16 and a resin matrix 20. The reinforcing mat of the present
invention
is typically located at or near wall structures 14 and 16 to increase
transverse
strength, although other configurations are possible (see Figure 2A). In the
embodiment of Figures 1 and 1A, the pultruded part 10 is a window sash rail,
although numerous fenestration and non-fenstration products can be made using
the
present invention. As used herein, "fenestration products" refers to windows,
doors,
skylights, shutters, and components thereof, such as for example window j
ambs, sills,
heads, sash stiles, sash rails, door thresholds, and the like.
Figure 2 illustrates a portion of the pultruded part 10 and a reinforcing
mat 18. Pultruded body 12 has wall structures 14 and 16 each including the
reinforcing mat 18 located on opposite sides of the resin matrix 20. The resin
matrix
20 includes longitudinally extending reinforcing fibers, referred to herein as
longitudinal rovings 22. The rovings 22 function to give the pultruded part 10
longitudinal strength and modulus. A reinforcing mat 18 provides the
pultrusion
walls 14 and 16 transverse strength to resist transverse forces "F" by
locating
transverse oriented reinforcing fibers in the part. The resin matrix 20
preferably
surrounds and impregnates the longitudinal rovings 22 and the reinforcing mat
18. A
relatively thin layer 24 of the resin 20 covers the outer face of each of the
reinforcement mats 18 to provide the desired surface characteristics. The
resin
matrix 20 preferably impregnates the reinforcing mat 18.
Figure 2A illustrates an alternate wall structures 14A and 16A for a
pultruded part l0A in accordance with the present invention. A reinforcing mat
19A
is located near the interior, rather than near the surfaces. In the
illustrated
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embodiment, one or more layers of rovings 22A are positioned on both sides of
reinforcing mats 18A and 19A. The pultruded part 10A exhibits alternating
layers of
reinforcing mats 1 8A, 19A and rovings 22A. A thin layer 24A of resin forms
the
surface of the wall structures 14A and 16A.
As illustrated in Figure 2A, the layers of reinforcing mat and rovings
can be arranged in a variety of configurations and the present invention is
not limited
to locating the reinforcing mat on an outer surface of the pultruded part. The
present
reinforcing mats 18 or 18A permit the manufacture of pultruded parts with wall
thicknesses of about 0.10 inches, and preferably about 0.06 inches and more
preferably about 0.03 inches or less.
The resin matrix 20 comprises about 20-40% of the cost of the
pultruded part 10. Minimizing wall thickness minimizes resin cost. The thin
reinforcing mat 18 with high transverse strength of the present invention
permits a
reduction in wall thickness without coinpromising transverse strength.
The present reinforcing mat typically has a compressed thickness of
about 0.004 inches to about 0.020 inches. In another embodiment, the
reinforcing
mat has a compressed thickness of about 0.010 inches to about 0.012 inches.
Since
the reinforcing mat can be made relatively thin with a low areal density and
reinforcing fibers oriented in the transverse direction, the present
reinforcing mat can
be used to make relatively thin pultruded parts.
In some embodiments, pultruded parts may be manufactured using the
thin reinforcing mats of the present invention in which the profile consists
of resin
impregnated longitudinal rovings or reinforcing fibers totaling a thickness of
about
0.019 inches, with a resin impregnated reinforcing mat layer about 0.010
inches thick
on each sides of the rovings, for a total wall thickness of about 0.039 inches
or less.
In another embodiment, the wall thickness is about 0.045 inches to about 0.025
inches. The present reinforcing mat permits about a 33% reduction in wall
thickness
with the same or greater transverse strength than pultruded parts reinforced
with
conventional continuous filament mats. Wall thickness of about 0.039 inches
using
the present reinforcing mats have demonstrated a transverse tensile strengths
of about
20,000 psi.
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As used herein, "reinforcing fiber" refers to a single filament such as a
monofilament, or a grouping of a plurality of pliable, cohesive threadlike
filaments,
including without limitation glass fibers, natural fibers, carbon fibers,
metal fibers
(such as for example aluminum), ceramic fibers, synthetic or polymeric fibers,
composite fibers (such as a polymeric matrix with a reinforcement of glass,
natural
materials, metal, ceramic, carbon, and/or synthetics components), or a
combination
thereof. Although the Figures illustrate the reinforcing fibers schematically
as a
single entity or structure, each discrete reinforcing fiber illustrated herein
can be
interpreted as either a single filament, such as a monofilament, or a group of
filaments. As used herein, "roving" refers to a plurality of reinforcing
fibers.
Rovings are typically not twisted or kinked so that maximum longitudinal
strength is
maintained.
Figure 3 schematically illustrates a pultrusion system 111 suitable for
use with a reinforcing mat in accordance with the present invention. One or
more
reinforcing mats 18', 18" (referred to collectively as "18") are directed from
source
rolls 116, 140, respectively over illustrated rollers 118 and/or 120 to resin
bath 122.
The wetted reinforcing webs 18 pass over roller 124 into the pultrusion die
54. A
plurality of longitudinal rovings 126 from source roll 128 passes over roller
130,
through resin bath 132, and then over rollers 134, 136 and 138 into the die
54. The
pultrusion die 54 typically has a profile corresponding to or otherwise needed
to form
the cross-sectional shape of the pultruded part 12. The longitudinal fibers
are
typically 675-yield (about 675 yards per pound), 450-yield, 250-yield, or 113-
yield
glass reinforcing fibers, although fibers with other yields or non-glass
fibers can be
used for some applications.
A variety of techniques well known to one skilled in the art such as
carding plates can be used to pre-form or pre-shape the rovings and the
reinforcing
mats 18 for pulling through the die 54. The reinforcing mats described herein
can be
used in pultrusion processes using the same techniques as are used for
conventional
mats. The rovings and the reinforcing mats are collated together for passage
through
the die but are generally not connected until unified by the setting resin. In
another
embodiment, the reinforcing mats 18 are attached to some of the longitudinal
rovings
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126, such as by stitching, adhesives and other attaching techniques. In yet
another
embodiment, the reinforcing mats 18 can be trapped between layers of rovings,
such
as illustrated in Figure 2A. As the longitudinal rovings 126 are pulled
through the die
54, the mats 18 are pulled along. The reinforcing mat 18 can be shaped using
the
same mechanisms used to position the longitudinal rovings 126 relative to the
die 54.
Prior to entering the die, the reinforcing mats 18 are preferably shaped
to correspond generally with the profile of the die 54. Roll forming analogous
to
those used in forming sheet metal and/or heat-setting techniques can be used
to shape
the reinforcing mats 18. Other suitable methods for shaping the mats 18 are
disclosed in U.S. Patent Nos. 4,752,513 (Rau et al.) and 5,055,242 (Vane).
Pulling mechanism 52, which for example may coinprise a pair of
opposing rollers, is operable to pull part 12 from a pultrusion die 54.
Instead of
passing the longitudinal rovings 126 and the reinforcing mats 18 through
respective
resin baths 122, 132, as shown schematically in Figure 3, resin may be applied
to the
reinforcing fiber and the reinforcing mats 18 using conventional resin-
applying
procedures that are well known to those skilled in this art. Various
techniques for
making pultruded parts are disclosed in U.S. Patent Nos. 4,564,540 (Davies et
al.);
4,752,513 (Rau et al.); 5,322,582 (Davies et al.); and 5,324,377 (Davies).
The positioning of the longitudinal rovings 126 and the reinforcing
mats 18 relative to the die 54 in Figure 3 is purely schematic and may change
depending upon the desired position of the reinforcing mats 18 and the
longitudinal
rovings 126. The reinforcing mats 18 and the longitudinal rovings 126 can be
located
anywhere in a pultruded part. For example, as illustrated in Figure 2A,
alternating
layers of reinforcing mats 18A, 19A and longitudinal rovings 126 can be
located
throughout the pultruded part 12. In some embodiments, the longitudinal
rovings 126
may be closest to the surface of the part, rather than the mat.
A conventional pultrusion resin formulation may be used for
pultruding part 10. A typical formula may include, for example, a mixture of
themzoset polyester resin containing a reactive diluent such as styrene, along
with a
hardener, a catalyst, inorganic fillers, a suitable surface modifier, and a
die lubricant.
Suitable resins are disclosed in U.S. Patent Nos. 4,752,513 (Rau et al.);
5,908,689
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(Dana et al.); and 5,910,458 (Beer et al.). A commercially available thermoset
resin suitable for use in the present invention is available from Resin
Systems
Incorporated located in Edmonton, Alberta under the product designation
Version
G. Other suitable suppliers may include Reichhold, Ashland, and Dow.
Thermosetting matrix materials useful in the present invention can
include thermosetting polyesters, vinyl esters, epoxides, phenolics,
aminoplasts,
thermosetting polyurethanes, derivatives and mixtures thereof. Suitable
thermosetting polyesters include the AROPOLTM products that are commercially
available from Ashland Chemical Inc. of Columbus, Ohio. Examples of useful
vinyl esters include DERAKANE®TM products such as
DERAKANE®TM 470-45, which are commercially available from Dow
Chemical USA of Midland, Michigan. Examples of suitable commercially
available epoxides are EPON®TM 826 and 828 epoxy resins, which are epoxy
functional polyglycidyl ethers of bisphenol A prepared from bisphenol-A and
epichlorohydrin and are commercially available from Shell Chemical.
Non-limiting examples of suitable phenolics include phenol-
formaldehyde from Monsanto of St. Louis, MO, cellobond phenolic from
Borden of Columbus Ohio, and specific phenolic systems formulated for
pultrusion fromBP of Chicago Illinois, Georgia Pacific of Atlanta Georgia, and
Inspec (Laporte Performance Chemicals) of Mount Olive New Jersey.
RESIMENETM 841 melamine formaldehyde from Monsanto. Useful aminoplasts
include urea-formaldehyde and melamine formaldehyde. Suitable thermosetting
polyurethanes include Adiprene PPDI-based polyurethane supplied by
Uniroyal Chemical Company, Inc. of Middlebury, Connecticut and
polyurethanes that are available from Bayer of Pittsburg, Pennsylvania,
Huntsman of Edmonton, Alberta, and other resin formulators such as E. I. du
Pont de Nemours Co. of Wilmington Delaware. Other components which can be
included with the thermosetting matrix material and reinforcing mat in a
pultruded part are, for example, colorants or pigments, lubricants or process
aids,
ultraviolet light'(UV) stabilizers, antioxidants, other fillers, and
extenders.
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The resin used in producing the pultrusion product can be filled with
other materials, either at the longitudinal reinforcing fiber area, at the
surface mat
areas, or both. Fillers are generally present in amounts ranging from a trace
amount to 30 percent, preferably 10 to 25 percent and most preferably 15
percent.
The fillers may be any suitable filler utilized by the art to fill a resin
system of the
type being produced. Fillers and pigments such as calcium carbonate, titanium
dioxide, hydrated alumina, kaolin clay, silicon dioxide, carbon black and the
like
may be used. Wood flour, recycled plastic grinds, metal grinds such as
ValimetTm
H2 spherical aluminum powder or Hoeganaes AncoorsteelTm 1000 atomized steel
powder, fly ash, or the like, can also be used to reinforce or fill the resin
of the
pultruded part, to obtain improved mechanical properties, to improve
aesthetics, to
increase or decrease density, or to reduce cost. Wood-fibers may be employed
to
achieve a natural-wood color in the pultruded product, in addition to the
enhanced
strength and lowered material cost.
Figures 4 and 5 illustrate one embodiment of a reinforcing mat 18A
in accordance with this invention. The reinforcing mat 18A includes a series
of
separate, transversely spaced, reinforcing fibers 28 (also referred to as
transport
fibers) comprising a first longitudinal layer 30. In the illustrated
embodiment, the
first layer 30 is made up of relatively fine reinforcing fibers 28 extending
longitudinally in the 0 or pull direction 29 of reinforcing mat 18A. These
reinforcing fibers 28 can be oriented in the range of 0 to about +/- 20 , and
G
preferably about +/- 10 , and more preferably +1-5 . As used herein, the term
"layer" refers to-the schematic illustration of the various reinforcing fibers
in the
Figures and is not intended to limit the structure of the present reinforcing
mat.
A second set of spaced reinforcing fibers 32 comprising a transverse
second layer 34 extend at an angle of about 90 with respect to the pull
direction
29. Reinforcing fibers 32 are desirably positioned in substantially directly
side-by-
side, non-overlapping, slightly spaced relationship to form a blanket of
fibers
without substantial breaks therebetween. As used herein, "non-overlapping"
refers
to generally coplanar fibers that do not extend over or cover one another.
Each of
the reinforcing fibers 32 preferably extend continuously across the width of
reinforcing
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mat 18A from edge portion 43 to edge portion 45. As used herein, "extend
continuously" refers to a single strand of reinforcing fiber running in an
unbroken
segment from one edge of a reinforcing mat to another edge. The 90
orientation of
the reinforcing fibers 32 maximizes the transverse strength and increased
modulus of
the pultruded part 10. In lieu of the preferred 90 orientation, the
reinforcing fibers
32 may be positioned at other angularities within the range of about 90 +/-30
and
more typically about 90 +/-20 (relative to the 0 or pull direction 29) in
the plane of
the mat.
In the illustrated embodiment, the reinforcing fibers 32 have a
substantially larger cross-sectional profile than the cross-sectional profile
of each of
the elongated reinforcing fibers 28, as is evident from the schematic
representations
of Figures 4 and 5. In an embodiment where the transverse reinforcement fibers
32
extending in the 90 direction (+/- 30 ) are not overlapping (see e.g.,
Figures 4 and 5),
they preferably comprise at least 30%, and more preferably at least 40%, of
the total
volume of material comprising the reinforcing mat 18A. In an embodiment where
the first reinforcing fibers 32 are overlapping (see e.g., Figures 27 and 28),
the
reinforcing fibers extending in the 90 direction (+/- 30 ) direction
preferably
comprise at least 40%, and more preferably at least 50%, of the total volume
of
material comprising the reinforcing mat 18A. As used herein, the pull
direction
29 is designated 0 . The orientation of all other reinforcing fibers will be
referenced
from the pull direction 29. The pull direction 29, however, is independent of
the
orientation of any particular reinforcing fiber. The reinforcing mat 18 can be
oriented
in any direction for pulling through the pultrusion die, although some
directions are
preferred over other. For most applications, however, the larger reinforcing
fibers 32
are preferably oriented transverse from the pull direction 29. As used herein,
"transverse" refers to a direction generally perpendicular to the 0 or
longitudinal pull
direction +/- 30 , and typically +/-20 , in a plane of a reinforcing mat.
Angular reinforcing fibers 38 comprising an angular reinforcing layer
36 extend at an angle of about 45 with respect to the pull direction 29. In
the
illustrated embodiment, the reinforcing layer 36 is located adjacent to the
layer 34.
The reinforcing fibers 38 shown in Figures 4 and 5 have a smaller cross-
sectional
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area as compared with the cross-sectional area of transverse reinforcing
fibers 32.
Another angular reinforcing layer 40 is located adjacent to the layer 36. The
reinforcing fibers 42 are desirably at angle of about 45 with respect to the
0 or the
pull direction 29. The angularity of reinforcing fibers 38 may be
characterized as +
45 while the angularity of reinforcing fibers 42 may be characterized as - 45
both
with respect to the 0 or the pull direction 29. The reinforcing fibers 38 and
42 of
angular layers 36 and 40 may be positioned in diagonal directions within the
range of
about +30 to about +60 and from about -30 to about -60 , respectively. The
angular reinforcing fibers 38 and 42 operate, at least in part, as transport
fibers that
provide longitudinal strength, shear strength and skew resistance. As used
herein,
"transport fiber" refer to fibers that assist in maintaining the integrity of
the
reinforcing mat as it is drawn through the pultrusion die.
The reinforcing fibers 38 of layer 36 and reinforcing fibers 40 of layer
42, extending in opposite directions at 45 angles impart shear strength to
the
reinforcing mat 18A. This increased shear strength is attributable to the fact
that
reinforcing fibers 38 of layer 36 and reinforcing fibers 42 of layer 40
transmit forces
substantially equally in the opposite directions to edge portions 43 and 45 of
the mat.
By providing such diagonally and oppositely oriented fibers at + 45 and - 45
, there
is minimal tendency for one of the edge portions 43 or 45 to move in advance
of the
other edge and thus a twisting or skewing the reinforcing mat during
pultrusion of
part 10. As used herein, "skew" refers to a change in the angular relationship
of
reinforcing fibers in the plane of a reinforcing mat. Skew typically is
exhibited by
one side edge of the reinforcing mat moving in advance of the other side edge
during
pultrusion.
The reinforcing fibers 38 and 42 are preferably continuous and extend
across the width of the reinforcing mat so as to maximize transmission of
forces in
respective diagonal directions. The volume of reinforcing fibers in the layer
36 is
preferably about the sanle as in the layer 40 so that there is a generally
uniform
resistance to skewing and shear strength stiffness modulus throughout the
reinforcing
mat 18A. Layer 30, in conjunction with layers 36 and 40, gives the reinforcing
mat
18A dimensional stability in the 0 and +/- 45 directions so that the
reinforcing mat
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18A can be bent to make pultr-uded parts with complex shapes, yet offer
sufficient
tracking consistency and necking-resistance for consistent processing during
pultrusion.
A permeable transport layer 44 is located adjacent to the layer 40,
although one or more reinforcing layers 44 can be located between any of the
layers
30, 34, 36, 40 of Figure 5. In the illustrated embodiment, the permeable
transport
layer 44 comprises a permeable transport web comprising a plurality of
relatively
short staple fibers or cut fibers 46. The permeable transport layer 44 is
preferably
made up of randomly oriented staple or cut fibers of a length within the range
of
about 0.01 to about 12", and preferably in the range of about 1/2" to about
4". The
staple fibers are preferably heat-fusible fibers. As used herein, "permeable
transport
web" refer to a plurality of staple fibers attachable to various reinforcing
fibers in a
reinforcing mat to provide longitudinal strength, shear strength and anti-skew
properties. Prior to attachment to the reinforcing fibers, the staple fibers
can be a
collection of loosely associated fibers, a batting material, or a variety of
other
configurations. As will be discussed in detail below, in some embodiments the
perineable transport web operates in combination with other transport
components,
such as binders, stitching fibers, adhesives, thermal bonding, various methods
for
entangling the staple fibers with the reinforcing fibers, diagonal reinforcing
fibers
(also referred to as transport fibers), and the like.
A proportion of fibers 46a are deflected from the plane of the layer 44
to become randomly oriented, intertwined and entangled with the reinforcing
fibers
28, 32, 38, 42. The staple fibers or cut fibers 46a effectively mechanically
interconnect or attach the layers 30, 34, 36, 40 and 44. The entangling fibers
46a
preferably extend substantially through the thickness of reinforcing mat 18A
and
prevent the layers 30, 34, 36, 40 and 44 from separating or moving one with
respect
to another as the reinforcing mat 18A is pulled through a pultrusion die 54.
The
reinforcing layer 44 also maintains the relative position of the respective
fibers 28,
32, 38, 42 in the reinforcing mat 18A.
In addition to interconnecting the layers 30, 34, 36, 40 and 44, the
layer 44 provides strength and resistance to skew in substantially all
directions.
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Additionally, while the layer 30 provides strength primarily in about the 0
or pull
direction 29, the fibers 28 will resist skewing forces at some angles other
than 0 .
Similarly, the fibers 32 will resist skewing forces at some angles other than
90 and
the fibers 38, 42 will resist skewing forces at angles other than +/- 45 . It
is the
combined effect of the reinforcing layer 44 and the various fiber layers 30,
34,36, 40
that provide the present reinforcing mat 18 with the properties that make it
suitable
for pultrusion.
The contributions of the fibers 28 and 42 in combination with the
reinforcing layer 44 provides the reinforcing mat 18A with sufficient in-plane
mechanical stability so that thin walled pultruded parts can be made with
minimal
skewing of the reinforcing mat 18 and minimal shifting of the relative
position of
fibers 28, 32, 38, 42. For a planar reinforcing structure, the plirase "in-
plane
mechanical stability" refers to a resistance to defoirnation and skew in the
plane of
the article sufficient to use in a pultruded part having a non-planar profile.
In another embodiment, the layers 30, 34, 36, 40 and 44 can be
interconnected or attached by stitching with a fiber 47 using a conventional
multi-
head stitching machine used in the textile industry. It can be seen in Figures
4 and 5
that the fiber 47 pass through and interconnect all of the layers 30, 34, 36
and 40 of
reinforcing mat 18A. In another embodiment, the layer 44 can also be stitched
to the
other layers 30, 34, 36 and 40. In yet another embodiment, the first
reinforcing fibers
32 can be spaced apart and attached together by continuous fiber stitching 47.
In the embodiment illustrated in Figure 5, the stitching fiber 47 wraps
around some of the reinforcing fibers 32. In embodiments where the reinforcing
fibers 32 are groupings of filaments, the stitching fiber 47 can pass between
individual filaments in the reinforcing fibers 32 (see e.g., Figure 20).
The fiber 47 illustrated in Figures 4 and 5 are schematic only. By
virtue of the flexibility of the individual stitches interconnecting layers
30, 34, 36 and
40, the reinforcing mat remains highly flexible, although mechanically
interconnected in a stabilized manner by the fiber 47. The fiber 47 can be
polyester
thread, a natural fiber thread as for example cotton, or a variety of other
known
materials.
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In another embodiment, the layers 30, 34, 36, 40 and 44 may be
interconnected or attached using a variety of other techniques. As used
herein,
"attach" refers to mechanical and or chemical techniques, including without
limitation stitching, entangling strands of staple fibers or cut fibers
intimately with
the reinforcing fibers, thermal bonding, ultrasonic welding, adhesive bonding,
conductive and non-conductive binders, mechanical entanglement, hydraulic
entanglement, vacuum compaction, or combinations thereof. Adhesive bonding
includes pressure sensitive adhesives, thermosetting or thermoplastic
adhesives,
radiation cured adhesives, adhesives activated by solvents, and combinations
thereof.
Binders may also include a thermoplastic resin sheathing on certain or all of
the
reinforcing fibers, or such resin sheathing may if desired take the place of
an added
thermoplastic binder. Suitable binders are disclosed in U.S. Patent Nos.
4,752,513
(Rau et al.); 5,908,689 (Dana et al.); and 5,910,458 (Beer et al.).
The present reinforcing mat 18A has a modulus of elasticity in the
transverse or 90 direction that is greater than the modulus of elasticity in
the 0 or
pull direction. The ratio of the modulus of elasticity in the transverse
direction to the
modulus of elasticity in the 0 or pull direction is preferably at least 1.2,
more
preferably 1.5, and still more preferably 3. In some embodiments the ratio is
at least
5. As used herein, "modulus of elasticity" refers to a ratio of the increment
of some
specified form of stress to some specified form of strain, such as Young's
modulus,
the bulk modulus, or the shear modulus. Modulus of elasticity can also be
referred to
as the coefficient of elasticity, the elasticity modulus, or the elastic
modulus.
Modulus of elasticity can be evaluated using ASTM D76-99 (Standard
Specification
for Tensile testing Machines for Textiles).
The present reinforcing mat can also be used for all other composite
processes, and is especially capable of high-strength, due to the oriented
fibers, or
reduced thickness, to decrease part cost or weight. The reinforcing mat can be
used
in composite spray-up parts, filament wound parts, resin-transfer-molded
parts,
structural-reaction-injection molded parts, sheet-molding-compound parts,
vacuum-
bag parts, and other composite assemblies, to achieve a thin wall, low cost,
low
weight, high strength, or the like. The process of using this reinforcing mat
would be
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similar to the cuirent technologies of process, but thinner parts, or multiple-
mat
thickness parts would be produced, as could be understood by those skilled in
these
arts.
Figures 6-8 illustrate an alternate reinforcing mat 18B in accordance
with the present invention. The reinforcing mat 18B has a 0 layer 30' made up
of a
series of longitudinally extending reinforcing fibers 28'. The layer 30' is
adjacent to
transverse layer 34' made up of a series of side-by-side reinforcing fibers
32'.
Angular fiber layers 36' and 40' made up of reinforcing fibers 38' and 42',
respectively, are located on opposite faces of the 0 reinforcing fiber layer
30' and 90
transverse reinforcing fiber layer 34', respectively, as best shown in Figures
6 and 7.
The diagonally oriented reinforcing fibers 42 and 38 may have an angularity of
about
+/- 45 to angles within the range of about +/- 30 to about +/- 60 .
Permeable
transport layer 44' is positioned in overlying relationship to the outer face
of angular
reinforcing fiber layer 36'. The layer 44' comprises a series of relatively
short staple
fibers 46' with the entangled connecting fibers being designated by the
numeral 46a'.
Figures 11-13 illustrate a precursor web before the addition of a
permeable transport layer. Two longitudinally extending reinforcing layers 144
and
146 are provided on opposite sides of centrally located, substantially larger
reinforcing fibers in transverse layer 148. Two angular reinforcing layers 150
and
152 are positioned against the face of longitudinal layer 144 opposite
transverse layer
148. The angular reinforcing layers 150 and 152 are preferably oriented in
opposite
diagonal directions at about 45 with respect to the longitudinal length of
the mat.
Figure 14 illustrates a reinforcing mat 18C made from the precursor structure
of
Figure 13. A permeable transport layer 154 is positioned on top of the
diagonal
reinforcing fiber layer 150. The relatively short fibers of the permeable
transport
layer 154 are schematically shown as being entangled with the layers 144, 146,
148,
150, 152.
Figures 15-16 illustrate a reinforcing mat 18D in which diagonal
reinforcing fibers 160 and 162 are positioned at 70 angles with respect 0 or
the pull
direction 29. The layers 164 and 166 are located on opposite sides of the
layer 168
containing the transverse reinforcing fibers 170. The permeable transport
layer 172
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interconnects or attaches the layers 164, 166, 168, and 172. The diagonal
reinforcing
fibers 160, 162 provide adequate dimensional stability in the pull direction
29 so that
the 0 reinforcing fibers can be omitted.
Figures 19-20 illustrate another embodiment of a reinforcing mat 18E
in accordance with the present invention. The reinforcing mat 18E includes a
series
of elongated, separate, essentially parallel, spaced, transverse reinforcing
fibers 220
arranged to form a transverse reinforcing layer 222. The reinforcing fibers
220 of
reinforcing layer 222 are oriented at an angle of approximately 90 with
respect to 0
or the pull direction 29 of a part through the die 54. The reinforcing fibers
220 are
laid continuously across with width of the reinforcing mat 18E and lie in a
slightly
spaced, side-by-side relationship. As previously explained, transversely
oriented
reinforcing fibers increase the modulus of a pultruded part 10 reinforced with
reinforcing mat 18E. Although reinforcing fibers 220 illustrated at 90 in
Figure 19,
the reinforcing fibers 220 may be positioned at other angularities within the
range
from about 60 to about 120 in the plane of the mat. Also as previously
indicated,
transverse fiber reinforcing fibers 220 normally are present in an amount
within the
range of about 40% to about 90% of the total volume of material comprising the
reinforcing mat 18E.
Mat 18E also has two layers 224, 226 of angled reinforcing fibers 228,
230, respectively. As is most evident from Figure 19, the reinforcing fibers
228 of
layer 224 are at an angle of about +45 with respect to 0 while the
reinforcing fibers
230 of layer 226 are at an angle of about -45 . The reinforcing fibers 228,
230 of
layers 224, 226 are of a lesser diameter than the diameter of individual
transverse
reinforcing fibers 220 in order to maintain the as inuch of the volume of the
reinforcing mat 18E in the transverse or 90 direction.
The layers 224, 226, 228 are interconnected or attached by spaced,
parallel individual lines of stitching 232. In the embodiment of Figure 19,
the
reinforcing fibers 220 are typically groups of filaments through which the
stitching
232 can pass. From Figure 19 it can be seen that the lines of stitching 232
extend in
perpendicular relationship to reinforcing fibers 220. Each line of stitching
232 is
made up of a relatively straight bobbin thread 234 and a serpentine stitch
thread 236.
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The bobbin thread 234 of each line of stitching 232 generally lays in
underlying
relationship to the reinforcing fibers 220, while the stitch thread 236 of
each line of
stitching 232 extends into overlying relationship to the layer 224 of
reinforcing mat
18E, thus serving to interconnect layers 222, 224, 226. As used herein, a
"stitched
thread" is located on a front surface of a reinforcing mat and a "bobbin
thread" is
located on the opposite side of the mat.
It is also to be observed from Figure 19 that the upper right segments
236 of adjacent stitch threads 236 are offset from one another in a direction
perpendicular to reinforcing fibers 220. The lines of stitching are applied
using a
multiplicity of adjacent, mutually cooperative, individual stitching heads as
previously herein. Although polyester thread is preferred for lines of
stitching 232,
other common materials may be used such as cotton thread or other natural or
synthetic resin fibers, depending upon the pultrusion process, the mechanical
properties desired of for example a pultruded fenestration product, or other
pultruded
part.
A permeable transport layer 238 is provided in overlying relationship
to layer 224. The permeable layer 238 is preferably made up of randomly
oriented
staple fibers. At least a certain proportion of the staple fibers are
entangling fibers
240 that randomly extend through at least a part of the composite thickness of
reinforcing mat 18 and serve to further interconnect the individual layers
222, 224,
226, 238 of reinforcing mat 18 in conjunction with the lines of stitching 232.
The entangling fibers 240 are preferably hydro-entangled with layers
222, 224, 226 utilizing hydro-entanglement equipment and employing procedures
as
described herein. The closely spaced heads of the hydro-entangler divert
staple fibers
from the plane of the layer 238 thereby causing hydro jet diverted staple
fibers to
extend randomly in a direction through the thickness of the composite mat 18E.
To
that end, the staple fibers making up reinforcing mat 18E preferably have a
relatively
low resistance to bending so that randomly oriented fibers are forced
downwardly
into and through the layers of the reinforcing mat below using hydro-
entangling
equipment.
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Figures 21 and 22 illustrate an alternate reinforcing mat 18F similar to
that illustrated in Figures 19 and 20, except that the layers 322, 324, 326
and 328 are
attached without stitching. Transverse reinforcing fibers 320 are arranged at
90 to
the pull direction 29. Two angled reinforcing layers 324, 326 of angled
reinforcing
fibers 332, 334 oriented at about +/- 45 are positioned between the layer 322
and the
permeable transport layer 328. Fibers 330 from the layer 328 extend throughout
the
thickness of the reinforcing mat 18F to form a mechanical bond between the
layers
322, 324, 326, 328. Supplemental holes 336 are formed in the permeable layer
328
to facilitate wetting of the reinforcing mat 18F with resin during the
pultrusion
process. Secondary attaching techniques may also be used, such as the addition
of
binders and/or adhesives, thermal bonding, and the like.
Figures 23 and 24 illustrate an alternate reinforcing mat 18G in which
the layer 352 of reinforcing fibers 354 arranged at 90 from the pull
direction are
stitching 356. The first reinforcing fibers 354 are preferably spaced apart
and
attached together by continuous fiber stitching 356. The stitching 356 holds
the
reinforcing fibers 354 in an array during attachment of permeable transport
layer 358.
The permeable transport layer 358 is provided on at least one side of the
layer 352.
Staple fibers 360 of layer 358 are entangled with the reinforcing fibers 354
of
transverse reinforcement layer 352 to form a reinforcing mat with in-plane
mechanical stability. Supplemental holes 362 are formed in the permeable layer
358
to facilitate wetting of the reinforcing mat 18F with resin during the
pultiusion
process.
In another embodiment, the array of transverse reinforcing fibers 354
and the permeable transport layer 358 are stitched together to form a combined
structure. The stitching is preferably applied after hydraulic entanglement
and heat
fusing of the transverse reinforcing fibers 354 to the permeable transport
layer 358.
Figures 25 and 26 illustrate an alternate reinforcing mat 18H having a
layer 402 of transverse reinforcing fibers 404 arranged at about 90 relative
to the
pull direction 29. A permeable transport layer 406 is positioned on one side
of the
layer 402. Staple fibers 408 of the layer 406 are entangled with the layer 402
to form
a reinforcing mat 400 with in-plane mechanical stability. Supplemental holes
410 are
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formed in the layer 406 to facilitate wetting during pultrusion. In addition
to the
entangled staple fibers 408, other techniques disclosed herein may also be
used to
attach the layer 402 to the layer 406, such as thermal or adhesive bonding,
binders,
stitching and the like. In one embodiment, a second permeable transport layer
412 is
optionally located on the other side of the layer 402. Fibers 414 from the
layer 412
also entangle with fibers 408 from the layer 406. The second layer 412
reinforces the
reinforcing mat 18H, particularly if the layers 406 and 412 are thermally
bonded.
Figures 27 and 28 illustrate an alternate reinforcing mat 181 having two
layers 420, 422 of transverse-acting reinforcing fibers 424, 426,
respectively. The
transverse-acting reinforcing fibers 424, 426 have a substantially larger
cross section,
corresponding generally to the transverse reinforcing fibers 32 in Figure 5.
In one
embodiment, the reinforcing fibers 424 are arranged at about 60 (+/- 15 )
relative to
the pull direction 29. The reinforcing fibers 424 are desirably positioned in
substantially directly side-by-side, non-overlapping, slightly spaced
relationship. The
reinforcing fibers 426 are arranged at about -60 (+/- 15 ) relative to the
pull
direction 29. The reinforcing fibers 426 also do not overlap with each other.
The
layers 420, 422, however, do overlap. As used herein, "overlap" refers to
fibers that
extend over or cover one another.
In another embodiment, the reinforcing fibers 424, 426 are arranged at
45 and -45 (+/-15 ), respectively. While the orientation of the fibers 424,
426 in
these two embodiments are outside the definition of "transverse", arranging
the
reinforcing fibers 424, 426 at opposing angles in these ranges is desirable
for some
applications. In both embodiments, the reinforcing fibers 424, 426 preferably
comprises at least 30% of a volume of materials comprising the reinforcing mat
181,
and more preferably 40%.
A first permeable transport layer 430 is positioned on one side of the
layers 420, 422. Staple fibers 432 of the layer 430 are entangled with the
layers 420,
422 to form a reinforcing mat 181 with in-plane mechanical stability.
Supplemental
holes 434 are formed in the layer 430 to facilitate wetting during pultrusion.
In one
embodiment, a second permeable transport layer 436 is optionally located on
the
other side of the layers 420, 422. Fibers 432 from the layer 436 also entangle
with
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fibers 424, 426. The second layer 436 reinforces the reinforcing mat 181,
particularly
if the layers 430, 426 are thermally bonded. In another embodiment, an
additional
layer of reinforcing fibers is provided in the 0 direction to enhance pulling
strength
(see Figure 4).
Method of Making a Reinforcing Mat
Figure 9 illustrates an apparatus 78 for making the reinforcing mat 18
in accordance with the present invention. The apparatus 78 includes a conveyor
belt
80 arranged to carry the components of the reinforcing mat 18 fiom an initial
supply
to a wind-up device 82. The longitudinal length 84 of the belt corresponds to
the 0
direction of the reinforcing mat 18 during manufacturing.
A precursor web 85 is made by sequentially laying onto the belt 80 a
plurality of reinforcing fibers from supply units 86, 88, 90, and 92. A
plurality of
needles are preferably located along the edges of the belt 80. Supply head 90
continuously lays down reinforcing fibers along the longitudinal length of
belt 80,
thus providing a 0 lay of reinforcing fibers. Reinforcing fibers supply head
88 is
operable to reciprocate back and forth across the width of belt 80 to lay down
90
transverse reinforcing fibers. The reinforcing fibers are wound around needles
along
each edge of the endless belt 80 to arrange the reinforcing fibers for the
desired
orientations.
Angled reinforcing fiber supply head 92 lays down a reinforcing fibers
on the previously applied 0 and 90 reinforcing fibers at about a 45 angle.
Diagonal
reinforcing fiber supply head 86 functions to lay down reinforcing fibers at
an angle
of about -45 with respect to the longitudinal length 84 of the belt 80. The
head 86
traverses back and forth across belt 80 in timed relationship to the speed of
the belt
80 to provide angled reinforcing fibers. The angled reinforcing fibers are
wound
around the needles along each edge of the endless belt 80. Preferred results
have
been obtained by using 11 courses per inch of 90 reinforcing fiber, about 8
courses
per inch of 45 angular reinforcing fibers, and about 8 courses per inch of 0
reinforcing fibers in an assembled web 18.
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The present method permits the combination of 0 , 90 and +/-45
reinforcing fibers to be varied. For example, the 0 fibers can be eliminated
to
make a reinforcing mat similar to that illustrated in Figures 15 and 16. In
another
embodiment, only the 90 reinforcing fibers are applied, such as illustrated
in
Figures 25 and 26. Various methods for depositing the layers of reinforcing
fibers
are disclosed in U.S. Patent Nos. 4,484,459 (Hutson); 4,550,045 (Hutson);
4,677,831 (Wunner); and 5,308,424 (Sasaki et al.).
In one embodiment, a plurality of stitching heads 94 are provided
down stream of the supply units 86, 88, 90, 92. The stitching heads 94
optionally
form spaced, parallel lines of stitching in the layers of reinforcing fibers
(see e.g.,
Figure 20). The stitch thread can be polyester, aramid thread for toughness,
natural
fibers for cost, polyamides, such as Pegaso Micro HelanfilTM 2x80 dtex or
Honeywell Anso-texTM nylon, for resilience, or carbon threads for stiffness or
high-temperature capability. A suitable assembly for depositing the layers of
reinforcing fibers and stitching the layers together is available from LIBA
Maschinenfabrik GmbH of Germany under the trade designation Centra MaxTM 3
CNC fiber inserter.
In another embodiment, the stitching is omitted and the web 85 is
passed under a hot roll 98 to assist in bonding of the layers of the web 85
one to
another. The use of hot ro1198 is particularly suited when one or more of the
reinforcing fibers contain a polymeric component. The roll 98 act also to
calender
the web 85 so that it is compressed and slightly reduced in thickness. The
temperature of the roll 98 is preferably selected to cause the minimal amount
of
softening of the polymeric content and still achieve an adequate bond between
the
fibers. The roll 98 may also bond the polymeric components of the reinforcing
fibers by imparting ultrasonic energy. In another embodiment, the heat is
omitted
and a simple calendering action is used.
Non-woven machine 100 deposits polymeric cut-staple fibers onto
the web 85. The non-woven machine 100 can be a variety of structures, such as
for
example an air lay machine or a mechanical card. The staple fibers are the
precursor material for making the permeable transport layer discussed herein.
The
staple fibers
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are typically blended and carded, and a predetermined thickness is achieved by
stacking
a plurality of layers of staple-fiber webs or batting onto the web 85.
In one embodiment, the staple fibers comprise a non-woven batting web
may be made by blending of polyester staple fibers. The staple fibers
preferably include
a portion of high melt fibers and a portion of low melt fibers. In another
embodiment,
the low melt fibers are a bi-component fiber with a lugh melt portion and a
low melt
portion. The low melt portion provides a bonding function with the various
layers,
while the high melt portion minimizes warping and shrinkage of the reinforcing
mat 18
and excessive flow of the low melt polymer. A preferred bi-component fiber is
a core-
sheath configuration with the low melt polymer on the sheath and the high melt
polymer at the core. In one embodiment, the high melt fibers have a glass
transition
temperature of about 350 F and the low melt fibers have a glass transition
temperature
of about 270 F.
In another embodiment, the non-woven machine 100 may include
spinning needles that convert an open fiber polymeric material into high loft
"tufts" of
non-woven fibers. The tufts of high loft material are deposited in an
accumulator until a
target weight is reached, whereupon the tufts are dropped onto the web 85.
When more
than one type of open fiber polymeric material is used, separate accumulators
are used
so that the percentage of each type of material can be independently
controlled.
In one embodiment, the staple fibers are blended and opened in a non-
woven opener sold under the product referred to as a carding machine or garnet
wheel
sold by Sigma Fiber Controls of Simpsonville, SC. The staple fibers and/or cut
fibers
are then fed through a RandoTm webber so that a density of about 32 gram/meter
2 to
about 60 gram/meter2 is reached. The RandoTm feed and doff speeds are set to
achieve
the desired density. One or more layers of the non-woven batting is then
deposited on
the web 85.
After the staple fibers are laid onto the web 85, they are entangled with
the layers of reinforcing fibers. In the illustrated embodiment, the staple
fibers are
entangled using a water-jet hydro-entangler 66, such as the structure
illustrated in
Figure 10. The hydro-entangler 66 substantially compresses the staple fibers
to
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achieve the overall reinforcing mat thickness of about 0.004 inches to about
0.020 inches. The individual jets of water wet the randomly oriented fibers of
the staple fibers directly to the reinforcing fibers and force certain of the
fibers
into locations extending throughout the reinforcing mat 18. In some
circumstances the water jets from the hydra-entangler unit may break up some
of the fibers of the reinforcing fibers to produce shorten tangling fibers
randomly oriented in the same manner as entangling staple fibers. These broken
reinforcing fibers may extend throughout the cross-section of the web 18.
These
broken reinforcing fibers cooperate with the staple fibers to maintain the
layers
in proper relative relationship during processing of reinforcing mat 18 and in
the
use thereof as a reinforcement for a pultruded part.
Turning now to Figure 10, the web 85 with multiple layers of
reinforcing fibers 71 A, 71 B, 71 C, 71 D and the layer of staple fibers 73 is
fed
into a hydro-entangler 66 on a fine-mesh belt 76. In general, the hydro-
entangler
66 has upper manifold structure 68 receiving water from supply source 70
provided with a plurality of openings or nozzles 72 which direct water jets 74
directly onto the web. The water-jets delivered from nozzles 72 are preferably
pulsed so that the jet streams exit through respective nozzles 72 and pass
through the thickness of the web 85 until impacting the upper surface of a
fine
mesh belt 76. The water streams impacting against the upper surface of belt 76
cause the water to dissipate and thereby spread the fibers carried by the jet
streams transversely across the top of the belt 76 to enhance entanglement of
the
web 85.
A suitable hydro-entangler is commercially available from ICBT
PerfojetTM of Mont Bonnet, France. The ICBT PerfojetTM hydro-entangler has
three horizontally-spaced manifolds of the type shown schematically in Figure
10,
each having a row of water-jet nozzles 68, with the nozzles spaced at
approximately eight per inch, providing a total of 100 to 150 nozzle openings.
The
water is jetted onto the web 85 with the first manifold set at a water
pressure of
500 psig, the second at 1500 psig, and the third at 1500 psig. The web 85
becomes
entangled as the water jets from manifold 66 pass through the layered material
making up the reinforcing mat 18.
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The hydro-entangler has the capability to blow-in holes or enhance
existing holes in the web 85 to achieve higher permeability. Permeability is
useful to
allow resin to flow through the thickness of the reinforcing mat in the
pultrusion die,
to avoid harmful hydraulics or bubbling of the reinforcing mat at the
pultrusion die
entrance. When enhanced by hydro-entangling, the hole size and distribution
are
determined by the hydro-entangler back screen pattern and back screen mesh
size.
A mesh size of 24 x 48 wires/inch in the backside conveyor belt that
transports the web 85 through the hydro-entangling process has been used to
create
an array of holes 24x48 holes/inch2, to increase the permeability. A mesh size
of 10
x 10 wires/inch can also be used for some applications where the coarses mesh
allows
for larger holes, corresponding to a higher and more desirable permeability. A
permeability of 200-400 ft3/minute/ft2 of air, through the web 85 (at a
pressure
differential of 0.5" of water) is sufficient for the resin to penetrate the
reinforcing mat
18 during pultrusion, but a permeability of 600-800 ft3/minute/ft2 or higher
works
very well for subsequent pultrusion processing. In an alternate embodiment,
the hole
size and distribution is enhanced by a needling operation.
In lieu of using a hydro-entangler as described, a head (not illustrated)
may be provided which supports a series of barbed needles 142 as shown in
Figure
18. In this. case, the layer of staple fibers 73 should be opposite the points
142a of the
needles so that when the barbed needle penetrate the mat, the barbs 142b do
not
engage the fibers of the staple fibers 73. However, upon retraction of the
barbed
needles 142, the barbs 142b thereon engage certain of the relatively short
fibers and
pull all at least a portion of such fibers upwardly into the reinforcing fiber
layers and
to entangle the staple fibers with the reinforcing layers.
Turning back to Figure 9, the web 85 can optionally be fed into a
needler or perforator 108 that has a head 110 which supports a plurality of
parallel,
relatively closely-spaced needles 112 (Figure 17) located downstream of the
hot rolls
106. The head 110 is reciprocated to sequentially direct the needles 112
through the
reinforcing mat to form an array of perforations. The array includes
perforations
spaced both longitudinal and transversely so the series of needles across the
width of
the web 85 are punched through the web 85 as it moves forwardly to provide the
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required number of spaced perforations. The perforations increase the porous
nature
of the reinforcing mat 18 and allow penetration of resin to bond through the
reinforcing mat into the various components of the mat.
From 1 to about 5000 holes per square inch may be formed in the web
using perforator 108, but about 80 holes per square inch formed by #14 needle
size is
preferred in a rectangular grid pattern. The needler 108 may be of
conventional
design which functions at a rate of approximately 20 cycles or reciprocations
per
second. The holes may be round or polygonal and generally are of a diameter
what
may be characterized as pin holes. The hole pattern may be random, square,
rectangular, close-packed-hexagonal, or similar configurations. During
needling, the
needles can optionally be heated to about 160 F, by use of electric heat guns
placed
inside the needle box area, and blowing air through the length of the needle
board.
The flow of viscous resin (such as polyester resin) through the
reinforcing mat during the pultrusion process affects the speed of pultrusion
and the
quality of the pultruded part. The permeability of the reinforcing mat is
particularly
important at the die entrance for both a bath style and a resin-injection
style of
pultrusion.
Pemleability is measured using the procedures disclosed in ASTM
D737-96 Test Method for Air Permeability of Textile Fabrics, which is
incorporated
herein by references. The rate of air flow passing perpendicularly through a
known
area of fabric is adjusted to obtain a prescribed air pressure differential
between the
two fabric surfaces. From this rate of air flow, the air permeability of the
fabric is
determined. The pressure differential used was 0.5 inch column of water.
Reinforcement fiber mats which are parallel to the direction of
pultrusion typically have a permeability of at least about 180 ft3/minute/ft2.
To obtain
pultrusion speeds with 30% filler in the resin, permeability of 300-350
ft3/minute/ft2
is preferred. A permeability of about 300 - 350 ft3/minute/ft2 can be achieved
by
using a coarse mesh entangler-belt in the hydro-entangler, so that a smaller
number of
larger holes are created (in the range of about 50 holes per square inch) to
maximize
the capability of polyester resin flow through the mat. For some applications,
reinforcing mats with a permeability above 350 ft3/minute/ft2 meets can be
used.
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The web 85 is directed under a vacuum system 87 that draws most
of the water from the web 85. The substantially dried web 85 is then passed
through a forced-air oven 89. The oven 89 is preferably operated at a
temperature between the glass transition temperature of the low melt and high
melt staple fibers. The staple fibers preferably soften and bond, but do not
flow
sufficiently to reduce the permeability of the reinforcing mat 18.
In an alternate embodiment, the web 85 is passes between a pair of
hot rolls 106 which act to further calender the reinforcing mat and also to
melt
and activate the polyester fibers to provide a bonding action. In one
embodiment,
the rolls 106 are smooth 12 inch diameter smooth rolls on a B.F. Perkins
calender set at 120 C with a minimum gap of 0.007 inches. The rolls 106 reduce
the reinforcing mat thickness and fuse the polyester material into the
reinforcing
mat 18.
A binder or an equivalent powdered, solvent, thermal or aqueous
based thermoplastic binder is optionally applied to the reinforcing mat 18 by
dispenser 113. The web picks up this binder, and is then squeezed through the
rubber drying rolls 115 set at 30 psi, at the given speed per the needling
process.
Various binder materials can be applied to the reinforcing mat 18 to increase
stiffness, such as corn starch, polyvinyl acetate or similar binder material.
In one
embodiment, the binder material is a reactive modified latex binder applied to
the top surface of the reinforcing mat by an applicator which fills the
interstices
between the layers of the mat.
Binder is applied at a concentration adequate to impart the desired
stiffness to the reinforcing mat for pultrusion handling and processing. The
dry-
mat stiffness may be tailored for ease-of-processing. The reactive sites in
the
binder regulate the occurrence of cross-linking within the- binder upon
drying,
which renders those sited useless for the purpose of enhancing the strength of
the
pultrusion. Although a 10% reactive solution of Franklin DuracetTM X080 binder
has been found to be beneficial and therefore preferred for enhancement of
production strength, the level of binder reactive activity may be varied to
achieve particular processing strengths and product strengths desirable for
particular products.
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An adhesive binding material such as polyvinyl acetate in a water
carrier and containing about 20% to about 60% solids, corn starch or other
adhesive
material can be used to assist in interconnecting the structure so that the
entangled
fibers are bonded to the fibers of the reinforcing layers and the fibers are
bonded to
each other. Generally, the binding agent is present in an amount in the range
of 2%
to 20% by weight (dry weight without water). However, the amount of binding
agent
is significantly reduced relative to conventional non-woven mats and thus the
stiffness of the structure is very much reduced and therefore improved,
allowing the
reinforcing mat to bend to take up the complex shape of the part to be formed
while
restricting shear.
If the staple fibers and/or some of the reinforcing fibers have a
thermoplastic content, the binder can be reduced or omitted. Instead, the
fibers are
heated to provide some amount of heat bonding to each other. In the
arrangement
shown in Figure 9, some of the entangling fibers are of a high melting point
so that
they remain intact and thus act as entangling fibers, and some are of a lower
melting
point so that they act as bonding fibers. In some embodiments where the binder
is
not required for structural purposes, it may still be used to increase
stiffness.
The reinforcing mat passes through drying oven 114 that uses 200 F
air forced through the thickness to dry the mat. A suitable drying oven is
available
from National Drying of Cary, NC.' Once dried, the finished reinforcing mat 18
is
stored on rol182. The reinforcing mat 18 can optionally be slit longitudinally
to the
desired width for pultrusion prior to storage on the roll 82.
The calendering, needling, and padding steps can be rearranged,
processed multiple times, or omitted if the reinforcing layers are thermally
bonded
with a resin as explained in detail herein, depending on the desired
permeability,
stiffness, and thickness required for the mat, to optimize the pultrusion
process, and
the mechanical properties of the pultiuded product. The reinforcing mat
formation
may also be carried out on-line with the pultrusion process so as to avoid the
winding
and supply steps although in general this is unlikely to be practical in many
circumstances due to the different speeds of the processing lines.
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The reinforcing mat 18 as described provides reinforcement which has
sufficient structural strength in the longitudinal and shear directions to
ensure that it
will be transported through the pultrusion die without significant
longitudinal
deformation or skewing. This is attributable to the fact that the main bulk of
the
fibers are arranged in the transverse direction to provide the finished
product with the
required transverse strength. The number of fibers therefore necessary for a
predetermined transverse strength is significantly reduced since the bulk of
the fibers
are arranged in the direction to maximize the strength provided by each fiber.
Reinforcing mats of varying weight per square yard may be fabricated in
accordance with the present invention. Mats of 0.5-1.0 ounces per square yard
are
useful for str-uctural pultrusions with wall thickness of about 0.038 inches
to
unusually-high-strength pultrusions that are 0.090" thick, although other
sizes of
reinforcing mat and pultrusions can be made using this technology. The
internal
integrity of the present reinforcing mat permit strips as small as 0.5 inches
wide to be
slit without causing the reinforcing layers to delaminate.
For example, if G-150 yams are used as the reinforcement layer, then a
pultrusion wall thickness of 0.031" or less is feasible while retaining the
required
capability of a structural part having longitudinal strengths of approximately
40,000
psi, and transverse strengths of approximately 20,000 psi. On the other hand,
much
thicker glass fibers may be used to make thicker pultrusions with unusual high-
strength, due to the orderliness of the fiber orientation in the transverse
direction.
In addition, multiple layers of the reinforcing mat are useful in the
production of high-strength products, to achieve enhanced physical capability
in the
pultruded parts, by use of this technology. For example, if two or three
layers of the
mats are used in a regular structural pultrusion that is 0.25-inches thick,
then the
strength of the pultrusion can be increased in the transverse direction as
much as 200-
400%. The transverse stiffness of the thick pultrusion may also be adjusted by
a
factor of 200-400%, thereby enhancing the longitudinal capability of the
pultrusion
because the bucking strength of the composite pultruded profile is
dramatically
increased.
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In addition, one side of a pultrusion may be provided with multiple
reinforcing mat layers, or a thick reinforcing mat may be employed on the
compression side of the pultrusion product, while the other side of the
pultrusion may
be provided with a single layer on the tensile side. In the case of a hollow
or
channel-profile pultrusion, the outside of the part may be provided with a
single or
thin mat, while the inside of the pultruded part is provided with thicker or
multiple
layers of the reinforcement mats.
The stacking sequence of the layers of the reinforcing mat may also be
varied to achieve the different or enhanced capabilities. For example, in lieu
of the
sequence of layers of the preferred embodiment of reinforcing mat construction
as
illustrated in Figures 19 and 20, the permeable transport layer may be located
against
the outer face of the transverse glass reinforcing fibers, between the
transverse
reinforcing fibers and an adjacent transport layer, or between the oppositely
inclined
rovings.
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Reinforcin Fibers
ibers
The reinforcing fibers and the longitudinal rovings are preferably
compatible with the resin matrix. As used herein, the phrase "compatible" in
the
context of a thermosetting resin or matrix refers to fibers and other
components
of a pultrusion laminate or part are selected or treated so that they
facilitate
penetration and essentially complete wetting and impregnation of the fiber and
component surfaces by the thermosetting resin or matrix material, provide
desired physical properties of the cured or finished laminate or part, are
chemically stable with the thermosetting resin or matrix material and are
resistant to hydrolysis.
The primary reinforcing fiber and the longitudinal rovings used in
pultrusion are typically glass fibers. The 90 reinforcing fibers are
preferably a
900 yield E-glass fiber that has been treated with an organo-silane
composition
to increase reinforcement-matrix interfacial strength. The +/- 45 oriented
reinforcing fibers and the 0 direction reinforcing fibers are preferably
G150's
(15000 yards per pound) with a thermoplastic polyester resin sheathing
available from Engineered Yarns Incorporated of Fall River, MA.
Glass reinforcing fibers can be replaced with carbon fibers to
achieve higher stiffness, strength, or temperature capability. Graphite fibers
may for example be Mitsubishi Pitch K13C2U, HexcelTM PAN AS4, and
AmocoTM PAN T300. Glass reinforcing fibers can also be replaced with aramid
fibers for toughness or resilience, using for example Teijin TechnoraTM or
KevlarTM type aramid fibers, with KevlarTM type 29 being useful and KevlarTM
type 49 being preferred. Polyester fibers may be substituted for glass fibers
where extended elongation or toughness are requisite properties, or natural
fibers (e.g. cotton, jute, hemp) for cost. Metal and ceramic fibers may also
be
used.
The reinforcing fibers may be enhanced to improve the capability
of the mat, or to tailor the reinforcing mat to achieve improved performance,
including changes in geometry, stacking, materials, surface treatments such as
sizings, and binders. For example, the 0 reinforcing fibers and the +/-45
reinforcing fibers may be pre-coated with a thermoplastic synthetic resin
comprising an amide, a polyester,
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or a similar sheath-like binder. When subjected to elevated temperature, the
sheathing binder flows and thereby fuses the reinforcing fibers of all of the
layers of
the reinforcing mat together, thereby producing a windable pre-mat. In
addition,
acrylic, polyvinyl acetatec, or similar emulsions with cross-linkable sites
may be
deposited on the reinforcement fibers so that these fibers react in the
pultrusion
composite to enhance the mechanical properties of the reinforcing mat by
reinforcement of the fiber/resin interface. Methods of making a coated
reinforcing
fiber are disclosed in U.S. Patent No. 4,058,581 (Park).
Enhancement of the glass fibers may be accomplished by addition of a
surface treatment including an organosilane to the fiber surface to augment
the
strength and durability of the final pultruded product. The addition of a
coupling
agent such as an organosilanes has been found to increase the pultruded
product
physical properties, such as wet strength retention. For example, application
of an
organosilane to G75 glass fiber yarns used for the transport fibers results in
a stronger
and more durable pultruded product. When an organosilane coating is added to
the
reinforcing fibers, improved results were obtained when a cationic amino-
functional
silane. Tris (2-methoxyethoxyvinylsilane) and 3-
methacrylopropyltrimethoxysilane
are exemplary silanes.
The composition for treating preferably comprises a surface treatment
containing one or more coupling agents selected from the group consisting of
organo
silane coupling agents, transition metal coupling agents, amino-containing
Werner
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 react with the glass fiber surface and/or the components of the treating
composition. As used herein, the term "react" with respect to coupling agents
refers
to groups that are chemically attracted, but not necessarily chemically
bonded, to the
glass fiber surface and/or the components of the treating composition, for
example by
polar, wetting or solvation forces. Examples of suitable compatibilizing or
functional
groups include epoxy, glycidoxy, mercapto, cyano, allyl, alkyl, urethano,
halo,
isocyanato, ureido, imidazolinyl, vinyl, acrylato, methacrylato, amino or
polyamino
groups.
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CA 02469650 2007-02-01
Functional organo silane coupling agents are preferred for use in
the present invention. Examples of suitable functional organo silane coupling
agents include A- 187 gamma-glycidoxypropyltrimethoxysilane, A- 174
gamma-methacryloxypropyltrimethoxysilane and A-1100 gamma -
aminopropyltriethoxysilane silane coupling agents, each of which are
commercially available from OSi Specialties, Inc. of Tarrytown, N.Y. The
organo silane coupling agent can be at least partially hydrolyzed with water
prior to application to the glass fibers, preferably at about a 1:3
stoichiometric
ratio or, if desired, applied in unhydrolyzed form.
Suitable transition metal coupling agents include titanium,
zirconium and chromium coupling agents. The amount of coupling agent can
be 1 to about 10 weight percent of the composition for treating on a total
solids
basis.
Crosslinking materials, such as the aminoplasts discussed above,
can also be included in the composition for treating. Non-limiting examples of
suitable crosslinkers include melamine formaldehyde, blocked isocyanates such
as BAYBONDTM XW 116 or XP 7055, epoxy crosslinkers such as
WITCOBONDTM XW by Witco Corp., and polyesters such as BAYBONDTM
XP-7044 or 7056. The BAYBONDTM products are commercially available
from Bayer of Pittsburgh, Pa. The amount of crosslinker can be about 1 to
about 25 weight percent of the composition for treating on a total solids
basis.
The composition for treating can include one or more emulsifying
agents for emulsifying components of the composition for treating. Non-
limiting examples of suitable emulsifying agents or surfactants include
polyoxyalkylene block copolymers, ethoxylated alkyl phenols,
polyoxyethylene octylphenyl glycol ethers, ethylene oxide derivatives of
sorbitol esters and polyoxyethylated vegetable oils. Generally, the amount of
emulsifying agent can be about 1 to about 20 weight percent of the composition
for treating on a total solids basis.
The composition for treating can also include one or more
aqueous dispersible or soluble plasticizers to improve flexibility. Examples
of
suitable non-aqueous-based plasticizers which are aqueous dispersible
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plasticizers include phthalates, such as di-n-butyl phthalate; trimellitates,
such
as trioctyl trimellitate; and adipates, such as dioctyl adipate. An example of
an
aqueous soluble plasticizer is CARBOWAXTM 400, a polyethylene glycol which
is commercially available from Union Carbide of Danbury, Conn. The amount of
plasticizer is more preferably less than about 5 weight percent of the
composition
for treating on a total solids basis.
Fungicides, bactericides and anti-foaming materials and organic
and/or inorganic acids or bases in an amount sufficient to provide the aqueous
composition for treating with a pH of about 2 to about 10 can also be included
in
the composition for treating. Water (preferably deionized) is included in the
composition for treating in an amount sufficient to facilitate application of
a
generally uniform coating upon the strand. The weight percentage of solids of
the composition for treating generally can be about 5 to about 20 weight
percent.
Staple Fibers and/or Cut Fibers
Staple and/or cut fibers for making the permeable transport layer
include fibers from polymers such as randomly oriented, cut-staple polyester
fibers.
The staple fibers can be loosely associated or arranged in a sheet or batting
structure. The hydro-entangling jets grasp the staple and/or cut fibers and
carry
parts of the fibers into and through the reinforcing fiber layers, thus
effecting
entanglement and attachment of the underlying reinforcing fiber layers. The
staple
fibers preferably have a relatively low resistance to bending so that fibers
may be
moved downwardly by hydro-entanglement, by mechanical structure such as
barbed needles,'and the like.
Suitable staple fibers are polyester, although glass fibers of reduced
denier meeting the requisite flexibility requirements may be also used as the
staple
fibers. The polyester material making up permeable transport layer comprises a
batting of a blend of about 50%-70%Wellman 1.5 denier x 1.5" polyester staple
fiber, and about 30%-50%Kosa 1.5 denier by 1.5" long bi-component fiber,
crimped and baled. The Kosa fiber gives the batting web a heat-fusible
component,
while the Wellman fiber enhances the consistency of the polyester batting and
decreases shrink of the web during heat-fusing. After the blend is mixed, an
opener
filamentizes the fibers. The polyester batting in one embodiment has a density
of
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about 60 grams/m2 to about 300 grams/m2 and in another embodiment about 90
grams/m2 to about 150 grams/m2. As used herein, "denier" refers to the mass of
a
fiber divided by its length.
The polyester staple fibers can be replaced with polyethylene batting,
such as Honeywell SpectraTM 1000 or Honeywell SpectraTM 2000 fiber, or with a
high strength polyethylene fiber such as DyneemaTM SK60 of Toyobo Company.
A polyamide (nylon) batting may also be used. Furthermore, a textured, bi-
component or crimped thermoplastic or reactive thermoset staple fiber, powder,
or slurry; or combinations of the above fibers, powders, or slurries such as
Kosa
K90 and Wellman polyester staple fibers in water or preferably FIT and Wellman
polyester staple fibers in water as used in paper making processes may be
employed.
Blends of these staple fibers, powders, and slurries may also be
used to achieve desired levels of stiffness and fusability (high-shrink fibers
make
the heat-fusion step more dynamic by causing melting kinetics to focus on the
crossover-points of the reinforcement fibers). A blend of low-melt-flow index
and high-strength (high-melt index) staple fibers achieve a distribution of
reinforcing mat strengths, where the combination of melting kinetics (low-melt-
index), and staple-fiber strength (high-melt-index) was varied to provide
increased reinforcing mat integrity (longitudinal strength and resistance to
melting at the pultrusion die entrance and within the pultrusion die).
The filament diameter size, in a range of about 9 to 25 microns, and
the effective bundle diameter size, in a range of about 0.010-inches to about
0.10-inch, can be adjusted to achieve various dimensions of pultrusion mat.
The
reinforcement layer can be made very thin, by the use of G150 yams, or
smaller.
The strength of the mat, and corresponding pultrusion, can be increased, but
the
distribution of holes (for pultrusion resin wetting) might be lessened,
depending
on the evenness of the distribution of the G150 yarns. The reinforcement
reinforcing fibers may also be increased in size to 110 yield glass fibers
resulting
in a bulkier reinforcing mat of lower cost.
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Circular-Bending Stiffness
The reinforcement mats of the present invention have sufficient
stiffness to be pulled without wrinkling and to maintain tracking
(parallelism) to
minimize distortion during processing, yet retain sufficient suppleness to
allow the
reinforcing mat to conform to the shape of the perimeter of the pultruded
part.
The stiffness of the reinforcing mat is measured according to the
procedure of ASTM D4032-94 Standard Test Method for Stiffness of Fabric by the
Circular Bend Procedure. ASTM D4032 evaluates the maximum force required to
push the fabric through an orifice in a platform. The maximum force is an
indication
of the fabric stiffness or resistance to bending.
The reinforcing mat preferably has a circular-bending stiffness within
the range of about 4 Newtons (1 kilogram-meter/second2) to about 15 Newtons. A
reinforcing mat having a value of less than about 4 Newtons generally does not
track
well in the pre-former ahead of the pultrusion die for a complex part. A
reinforcing
mat over about 15 Newtons circular-bending stiffness has been found to be so
stiff
that it may be difficult to shape in the pre-former. A circular-bending
stiffness of
over about 15 Newtons also results in a preformed reinforcing mat that has
undesirable wrinkles, or spans depressions, because the stiff reinforcing mat
cannot
follow the pre-form shaper. The stiffness of the reinforcing mat can be
readily
adjusted by the concentration and type of the binder used.
Mat Thickness
The mat thickness is measured by a tight squeeze of a digital calipers
from Mitutoyo Corporation. Generally three readings were taken, at three
different
spots, and the average was recorded.
Mat Tensile Stren tg
The reinforcing mat preferably has a tensile strength in the 90 or
transverse direction of about 200 lbs./inch as measured per ASTM D76-99. The
reinforcing mat has a tensile strength in the 0 or pull direction of at least
3 lbs./inch
as measured per ASTM D76-99, and more preferably at least 6 lbs./inch.
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Measurements were taken on samples about 3 inches wide x 6 inches
long (either longitudinal or transverse) prepared by marking off the area and
hand
shearing. The samples were each pulled at a rate of about 0.2 in/minute until
failure.
Load and elongation were recorded. The average of four samples was recorded.
EXAMPLE 1-Thermally Bonded Reinforcing Mat
A reinforcing mat, in a resin matrix, that provides high transverse
strength on the exterior or interior surface of a pultruded part such as a
sash stile or
rail, or a pultruded frame head, sill, or j anlb, or other products outside
the fenestration
industry. The cross-section of the pultruded part is a matrix of thermosetting
resin
with longitudinal and other-reinforcing fibers in the interior of the parts
profile
thickness. A first mat layer accounts for about 0.010 inches of the thickness
of the
pultruded part, the longitudinal-reinforcing fiber area is about 0.030" thick,
and the
opposite mat layer is also about 0.010" thick. The longitudinal reinforcing
fibers are
oriented in the 0 direction. These longitudinal fibers are mostly 675-yield
(about
675 yards per pound) glass reinforcing fibers.
The reinforcing mat is a multi-layered structure, with the longitudinal
direction (e.g. the pull direction) designated as the 0 . A first layer
includes a
plurality of about 1800-yield glass reinforcing fibers in the transverse or 90
direction
in the plane of the reinforcing mat set at about 10 courses per inch. A second
layer
includes of a plurality of an amide, polyester or reactive sheathed fiber
glass bundles
spaced about 4 per inch in about the +/- 45 directions in the plane of the
reinforcing
mat thermally bonded to the transverse glass fibers. A third layer includes of
a
plurality of an amide, polyester or reactive sheathed fiber glass bundles
spaced about
4 threads per inch in about the 0 direction in the plane of the reinforcing
mat
thermally bonded to the transverse glass fibers. A fourth layer includes a
plurality of
polyester fibers that have at least portions thereof which extend in the
thickness
direction through the third, second and/or first layers to effect a connection
therebetween, with a pre-entangled weight of about 32 grams per square meter.
In addition, the reinforcing mat includes holes primarily between the
transverse 1800-yield reinforcing fibers, like sieve-holes in the through-
thickness
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direction, with the holes numbering about eighty per square-inch in a
generally
rectangular grid pattern. A polyvinyl acetate-based binder adheres the
multiple layers
and/or the interstices within a given layer. The entire reinforcing mat
thickness
(slightly compressed during thickness measurement) is approximately 0.010-
inches.
Further, the reinforcing mat includes a back-side with alternately-spaced 0
fibers as
a third layer of a plurality of an amide, polyester or reactive sheathed glass
fiber
bundles spaced about 4 per inch in about the 0 direction in the plane of the
mat,
thermally bonded to the transverse glass fibers.
EXAMPLE 2--Polyester Stitched Reinforcing Mat
A reinforcing mat, in a resin matrix, that provides high transverse
strength on the exterior or interior surface of a pultruded part such as a
sash stile or
rail, or a pultruded frame head, sill, or jamb, or other products outside the
fenestration
industry. The cross-section of the pultruded part is a matrix of thermosetting
resin
with longitudinal and other-reinforcing fibers in the interior of the parts
profile
thickness. A first mat layer accounts for about 0.010 inches of the thickness
of the
pultruded part, the longitudinal-reinforcing fiber area is about 0.030" thick,
and the
opposite mat layer is also about 0.010" thick. The longitudinal reinforcing
fibers are
oriented in the 0 direction. These longitudinal fibers are mostly 675-yield
(about
675 yards per pound) glass reinforcing fibers.
The reinforcing mat is a multi-layered structure, with the longitudinal
direction (e.g. the pull direction) designated as the 0 . A first layer
includes a
plurality of about 1800-yield glass fibers reinforcing fibers substantially in
the
transverse or 90 direction in the plane of the mat, set at about 10 courses
per inch. A
second layer includes a plurality of about 6-denier polyester thread spaced at
about 6
threads per inch in the +45 directions in the plane of the mat is stitched to
the
transverse glass fibers. A third layer includes a plurality of about a 6-
denier polyester
thread spaced about 6 per inch in about the 0 direction in the plane of the
reinforcing
mat stitched to the transverse glass fibers. A fourth layer includes of a
plurality of
about 6-denier fibers that have at least portions thereof that extend in the
thickness
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direction through the third, second and/or first layers to effect a connection
therebetween with a pre-entangled weight of about 32 grams per square meter.
In addition, the reinforcing mat includes holes primarily between the
transverse 1800-yield reinforcing fiber with about eighty per square-inch in a
rectangular grid pattern. A polyvinyl acetate-based binder adheres the
multiple layers
and/or the interstices within a given layer. The entire reinforcing mat
thickness
(slightly compressed during thickness measurement) is about 0.010-inches.
The back-side of the reinforcing mat includes alternately-spaced 0
fibers as a third layer of a plurality of about a 6-denier polyester thread
spaced about
6 threads per inch in about the 0 direction in the plane of the reinforcing
mat and
stitched to the transverse glass fibers.
EXAMPLE 3-Glass Fiber Stitched Reinforcing Mat
A reinforcing mat, in a resin matrix, that provides high transverse
strength on the exterior or interior surface of a pultruded part such as a
sash stile or
rail, or a pultruded frame head, sill, or jamb, or other products outside the
fenestration
industry. The cross-section of the pultruded part is a matrix of thermosetting
resin
with longitudinal and other-reinforcing fibers in the interior of the parts
profile
thickness. A first mat layer accounts for about 0.010 inches of the thickness
of the
pultruded part, the longitudinal-reinforcing fiber area is about 0.030" thick,
and the
opposite mat layer is also about 0.010" thick. The longitudinal reinforcing
fibers are
oriented in the 0 direction. These longitudinal fibers are mostly 675-yield
(about
675 yards per pound) glass reinforcing fibers.
The reinforcing mat is a multi-layered structure, with the longitudinal
direction (e.g. the pull direction) designated as the 0 . A first layer
includes a
plurality of about 1800-yield fiberglass fibers reinforcing fibers
substantially in the
transverse or 90 direction in the plane of the reinforcing mat set at about
10 courses
per inch. A second layer includes a plurality of glass fiber bundles spaced
about 4
per inch in about the +45 directions in the plane of the mat, stitched to the
transverse fiberglass. A third layer includes of a plurality of about a 6-
denier
polyester thread spaced at about 4 threads per inch in the 0 direction in the
plane of
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the reinforcing mat and stitched to the transverse glass fibers. A fourth
layer includes
a plurality of polyester fibers that have at least portions thereof that
extend in the
thickness direction through the third, second and/or first layer to effect a
connection
therebetween with a pre-entangled weight of about 32 grams per square meter.
The reinforcing mat also includes holes primarily between the
transverse 1800-yield reinforcing fiber numbering about eighty per square-inch
in a
rectangular grid pattern. A polyvinyl acetate-based binder adheres the
multiple layers
and/or the interstices within a given layer. The entire reinforcing mat
thickness
(slightly compressed during thickness measurement) is about 0.010-inches. The
reinforcing mat also includes a back-side with alternately-spaced 0 fibers as
a third
layer of a plurality of a fiberglass bundles spaced about 4 threads per inch
in the 0
direction in the plane of the reinforcing mat and stitched to the transverse
fiberglass.
EXAMPLE 4-Heat-Fused Polyester Stitched Reinforcing Mat
A reinforcing mat, in a resin matrix, that provides high transverse
strength on the exterior or interior surface of a pultruded part such as a
sash stile or
rail, or a pultruded frame head, sill, or jamb, or other products outside the
fenestration
industry. The cross-section of the pultruded part is a matrix of thermosetting
resin
with longitudinal and other-reinforcing fibers in the interior of the parts
profile
thickness. A first mat layer accounts for about 0.010 inches of the thickness
of the
pultruded part, the longitudinal-reinforcing fiber area is about 0.030" thick,
and the
opposite mat layer is also about 0.010" thick. The longitudinal reinforcing
fibers are
oriented in the 0 direction. These longitudinal fibers are mostly 250-yield
(about
250 yards per pound) glass reinforcing yarn.
The reinforcing mat is a multi-layered structure, with the longitudinal
direction (e.g. the pull direction) designated as the 0 . The first layer
includes a
plurality of about 1800-yield fiberglass fibers reinforcing fibers
substantially in the
transverse or 90 direction in the plane of the reinforcing mat set at about 8
courses
per inch. A second layer includes a plurality of about G150 glass reinforced
yarn
spaced about 4 threads per inch in about the +/- 45 directions in the plane
of the
reinforcing mat adjacent to the transverse fiberglass. A third layer includes
a
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plurality of about a 150-denier polyester thread spaced about 5 threads per
inch in the
0 direction in the plane of the reinforcing mat and stitched through all the
layers.
The bobbin thread was G150 glass reinforced yarn. The fourth layer includes a
plurality of polyester staple fibers that have at least portions thereof that
extend in the
thickness direction through the third, second and/or first layer to effect a
connection
therebetween with a pre-entangled weight of about 60 grams per square meter.
The
polyester staple fibers are heat-fused at a temperature of about 350 to the
glass
reinforced yarns to act as an interlaminae-connector to the continuous fiber
layers.
The reinforcing mat also includes holes primarily between the
transverse 1800-yield reinforcing fiber numbering about fifty per square-inch
in a
rectangular grid pattern. A reactive modified latex binder adheres the
interstices
between the layers. The entire reinforcing mat thickness (compressed during
thickness measurement) is about 0.010".
EXAMPLE 5-Heat-Fused Smooth-Surface Polyester Stitched Reinforcing Mat
A reinforcing mat, in a resin matrix, that provides high transverse
strength on the exterior or interior surface of a pultruded part such as a
sash stile or
rail, or a pultruded frame head, sill, or jamb, or other products outside the
fenestration
industry. The cross-section of the pultruded part is a matrix of thermosetting
resin
with longitudinal and other-reinforcing fibers in the interior of the parts
profile
thickness. A first mat layer accounts for about 0.010 inches of the thickness
of the
pultruded part, the longitudinal-reinforcing fiber area is about 0.030" thick,
and the
opposite mat layer is also about 0.010" thick. The longitudinal reinforcing
fibers are
oriented in the 0 direction. These longitudinal fibers are mostly 250-yield
(about
250 yards per pound) glass reinforcing yarn.
The reinforcing mat is a multi-layered structure, with the longitudinal
direction (e.g. the pull direction) designated as the 0 . A first layer
includes a
plurality of about 1800-yield glass reinforcing fibers substantially in the
transverse or
90 direction in the plane of the reinforcing mat set at about 8 courses per
inch. A
second layer includes a plurality of about G150 glass reinforced yarn spaced
about 4
courses per inch in the +/- 45 directions in the plane of the reinforcing mat
adjacent
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to the transverse glass fibers. A third layer includes of a plurality of a
about 150-
denier polyester thread spaced about 5 per inch in the 0 direction in the
plane of the
reinforcing mat and stitched through all the layers mentioned above. The
bobbin
thread was G150 glass reinforced yarn. A fourth layer includes of a plurality
of
polyester staple fibers that have at least portions thereof which extend in
the
thickness direction through the third, second and/or first layer to effect a
connection
therebetween with a pre-entangled weight of about 120 grams per square meter.
The
polyester staple fibers are heat-fused at a temperature of about 350 to the
glass
reinforced yams to act as an interlaminae-connector to the continuous fiber
layers.
The reinforcing mat includes holes primarily between the transverse
1800-yield reinforcing fiber numbering fifty holes per square-inch in a
rectangular
grid pattern. A reactive modified latex binder adheres the interstices between
the
layers. The entire reinforcing mat thickness (compressed during thickness
measurement) is about 0.010".
EXAMPLE 6-Heat-Fused Stitchless Reinforcing Mat
A reinforcing mat, in a resin matrix, that provides high transverse
strength on the exterior or interior surface of a pultruded part such as a
sash stile or
rail, or a pultruded frame head, sill, or jamb, or other products outside the
fenestration
industry. The cross-section of the pultruded part is a matrix of thermosetting
resin
with longitudinal and other-reinforcing fibers in the interior of the parts
profile
thickness. A first mat layer accounts for about 0.010 inches of the thickness
of the
pultruded part, the longitudinal-reinforcing fiber area is about 0.030" thick,
and the
opposite mat layer is also about 0.010" thick. The longitudinal reinforcing
fibers are
oriented in the 0 direction. These longitudinal fibers are mostly 250-yield
(about
250 yards per pound) glass reinforcing yam.
The reinforcing mat is a multi-layered structure, with the longitudinal
direction (e.g. the pull direction) designated as the 0 . A first layer
includes a
plurality of 1800-yield fiberglass fibers reinforcing fibers substantially in
the
transverse or 90 direction in the plane of the reinforcing mat set at about 8
courses
per inch. A second layer includes a plurality of G150 fiberglass yam spaced
about 4
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courses per inch in the +/-45 directions in the plane of the reinforcing mat
adjacent
to the transverse glass fibers. A third layer includes a plurality of
polyester staple
fibers that have at least portions thereof which extend in the thickness
direction
through the third, second and/or first layer to effect a connection
therebetween with a
pre-entangled weight of about 120 grams per square meter. The polyester staple
fibers are heat-fused at a temperature of about 350 to the fiberglass yarns
to act as an
interlaminae-connector to the continuous fiber layers.
The reinforcing mat also includes holes primarily between the
transverse 1800-yield reinforcing fiber numbering about fifty per square-inch
in a
rectangular grid pattern. A reactive modified latex binder adheres the
interstices
between the layers. The entire reinforcing mat thickness (compressed during
thickness measurement) is about 0.010".
EXAMPLE 7-Heat-Fused Stitchless Reinforciniz Mat, Without 45 Reinforcing
Fibers
A reinforcing mat, in a resin matrix, that provides high transverse
strength on the exterior or interior surface of a pultruded part such as a
sash stile or
rail, or a pultruded frame head, sill, or jamb, or other products outside the
fenestration
industry. The cross-section of the pultruded part is a matrix of thermosetting
resin
with longitudinal and other-reinforcing fibers in the interior of the parts
profile
thickness. A first mat layer accounts for about 0.010 inches of the thickness
of the
pultruded part, the longitudinal-reinforcing fiber area is about 0.030" thick,
and the
opposite mat layer is also about 0.010" thick. The longitudinal reinforcing
fibers are
oriented in the 0 direction. These longitudinal fibers are mostly 250-yield
(about
250 yards per pound) glass reinforcing yam.
The reinforcing mat is a multi-layered structure, with the longitudinal
direction (e.g. the pull direction) designated as the 0 . A first layer
includes a
plurality of about 1800-yield fiberglass fibers reinforcing fibers
substantially in the
transverse or 90 direction in the plane of the reinforcing mat set at about 8
courses
per inch. A second layer includes a plurality of polyester staple fibers that
have at
least portions thereof that extend in the thickness direction through the
third, second
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and/or first layer to effect a connection therebetween, with a pre-entangled
weight of
about 100-200 grams per square meter. The polyester staple fibers are heat-
fused at a
temperature of about 350 to the glass reinforced yarns to act as an
interlaminae-
connector to the continuous fiber layers.
The reinforcing mat also includes holes primarily between the
transverse 1800-yield reinforcing fiber numbering about fifty per square-inch
in a
rectangular grid pattern. A reactive modified latex binder adheres the
interstices
between the layers. The entire reinforcing mat thickness (compressed during
thickness measurement) is about 0.010".
EXAMPLE 8-Heat-Fused Polyester Stitched Reinforciniz Mat Using Silane-Treated
Yarn
A reinforcing mat, in a resin matrix, that provides high transverse
strength on the exterior or interior surface of a pultruded part such as a
sash stile or
rail, or a pultruded frame head, sill, or jamb, or other products outside the
fenestration
industry. The cross-section of the pultruded part is a matrix of thermosetting
resin
with longitudinal and other-reinforcing fibers in the interior of the parts
profile
thickness. A first mat layer accounts for about 0.010 inches of the thickness
of the
pultruded part, the longitudinal-reinforcing fiber area is about 0.030" thick,
and the
opposite mat layer is also about 0.010" thick. The longitudinal reinforcing
fibers are
oriented in the 0 direction. These longitudinal fibers are mostly 250-yield
(about
250 yards per pound) glass reinforcing yarn.
The reinforcing mat is a multi-layered structure, with the longitudinal
direction (e.g. the pull direction) designated as the 0 . A first layer
includes a
plurality of G37-yield glass reinforced yarns treated with organosilanes. The
yarns of
the first layer are substantially in the transverse or 90 direction in the
plane of the
reinforcing mat set at about 8 courses per inch. A second layer includes a
plurality of
G150 fiberglass yarn spaced about 4 courses per inch in the +/-45-degree
directions
in the plane of the reinforcing mat adjacent to the transverse glass
reinforced yarns of
the first layer. A third layer includes a plurality of about a 100-denier
polyester
thread spaced about 5 threads per inch in the 0 direction in the plane of the
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reinforcing mat and stitched through all the layers mentioned above. The
bobbin
thread was a G150 glass reinforced yarn. A fourth layer includes a plurality
of
polyester staple fibers that have at least portions thereof which extend in
the
thickness direction through the third, second and/or first layer to effect a
connection
there-between with a pre-entangled weight of about 60 grams per square meter.
The
polyester staple fibers are heat-fused at a temperature of about 350 to the
glass
reinforced yarns to act as an interlaminae-connector to the continuous fiber
layers.
The reinforcing mat also includes holes primarily between the
transverse 1800-yield reinforcing fiber numbering about fifty per square-inch
in a
rectangular grid pattern. A reactive modified latex binder adheres the
interstices
between the layers. The entire reinforcing mat thickness (compressed during
thickness measurement) is about 0.010".
EXAMPLE 9-Heat-Fused Polyester Stitched Reinforcing Mat with Metallic 45
Reinforcing Fibers
A reinforcing mat, in a resin matrix, that provides high transverse
strength on the exterior or interior surface of a pultruded part such as a
sash stile or
rail, or a pultruded frame head, sill, or jamb, or other products outside the
fenestration
industry. The cross-section of the pultruded part is a matrix of thermosetting
resin
with longitudinal and other-reinforcing fibers in the interior of the parts
profile
thickness. A first mat layer accounts for about 0.010 inches of the thickness
of the
pultruded part, the longitudinal-reinforcing fiber area is about 0.030" thick,
and the
opposite mat layer is also about 0.010" thick. The longitudinal reinforcing
fibers are
oriented in the 0 direction. These longitudinal fibers are mostly 250-yield
(about
250 yards per pound) glass reinforcing yarn.
The reinforcing mat is a multi-layered structure, with the longitudinal
direction (e.g. the pull direction) designated as the 0 . A first layer
includes a
plurality of 1800-yield glass reinforced fibers substantially in the
transverse or 90
direction in the plane of the reinforcing mat set at about 8 courses per inch.
A second
layer includes a plurality of about 0.008" diameter aluminum wire spaced about
4
wires per inch in the +/-45 directions in the plane of the reinforcing mat
adjacent to
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the transverse fibers. A third layer includes a plurality of about a 100-
denier
polyester thread spaced about 5 threads per inch in the 0 direction in the
plane of the
reinforcing mat and stitched through all the layers mentioned above using a
G150
glass reinforced yarn as the bobbin thread. A fourth layer includes a
plurality of
polyester staple fibers that have at least portions thereof which extend in
the
thickness direction through the third, second and/or first layer to effect a
connection
there-between, with a pre-entangled weight of about 60 grams per square meter.
The
polyester staple fibers are heat-fused at a temperature of about 350 to the
fiberglass
yarns to act as an interlaminae-connector to the continuous fiber layers.
The reinforcing mat also includes holes primarily between the
transverse 1800-yield reinforcing fiber numbering about fifty per square-inch
in a
rectangular grid pattern. A reactive modified latex binder adheres the
interstices
between the layers. The entire reinforcing mat thickness (compressed during
thickness measurement) is about 0.010".
EXA_MPLE 10-Heat-Fused Polyester Stitched Reinforcing Mat without 45
Reinforcing Fibers
A reinforcing mat, in a resin matrix, that provides high transverse
strength on the exterior or interior surface of a pultruded part such as a
sash stile or
rail, or a pultruded frame head, sill, or jamb, or other products outside the
fenestration
industry. The cross-section of the pultruded part is a matrix of thermosetting
resin
with longitudinal and other-reinforcing fibers in the interior of the parts
profile
thickness. A first mat layer accounts for about 0.010 inches of the thickness
of the
pultruded part, the longitudinal-reinforcing fiber area is about 0.030" thick,
and the
opposite mat layer is also about 0.010" thick. The longitudinal reinforcing
fibers are
oriented in the 0 direction. These longitudinal fibers are mostly 250-yield
(about
250 yards per pound) glass reinforcing yarn.
The reinforcing mat is a multi-layered structure, with the longitudinal
direction (e.g. the pull direction) designated as the 0 . A first layer
includes a
plurality of about 1800-yield glass reinforcing fibers substantially in the
transverse or
90 direction in the plane of the reinforcing mat set at about 8 courses per
inch. A
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second layer includes a plurality of about a 100-denier polyester thread
spaced
about 5 per inch in the 0 direction in the plane of the reinforcing mat and
stitched through all the layers mentioned above using a G150 glass reinforced
yarn as the bobbin thread. A third layer includes a plurality of polyester
staple
fibers that have at least portions thereof which extend in the thickness
direction
through the third, second and/or first layer to effect a connection there-
between,
with a pre-entangled weight of about 120 grams per square meter. The polyester
staple fibers are heat-fused at a temperature of about 350 to the fiberglass
yarns
to act as an interlaminae-connector to the continuous fiber layers.
The reinforcing mat also includes holes primarily between the
transverse 1800-yield reinforcing fiber numbering about fifty per square-inch
in
a rectangular grid pattern. A reactive modified latex binder adheres the
interstices between the layers. The entire reinforcing mat thickness
(compressed
during thickness measurement) is about 0.010".
Various modifications and alterations of this invention will become
apparent to those skilled in the art without departing from the scope and
spirit of
this invention, and it should be understood that this invention is not to be
unduly
limited to the illustrative embodiments set forth herein.
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