U.S. patent application number 09/729232 was filed with the patent office on 2001-04-05 for laminated structures with multiple denier polyester core fibers, randomly oriented reinforcement fibers, and methods of manufacture.
Invention is credited to Ette, Robert, Fletemier, Todd, Long, Richard.
Application Number | 20010000162 09/729232 |
Document ID | / |
Family ID | 22558121 |
Filed Date | 2001-04-05 |
United States Patent
Application |
20010000162 |
Kind Code |
A1 |
Fletemier, Todd ; et
al. |
April 5, 2001 |
Laminated structures with multiple denier polyester core fibers,
randomly oriented reinforcement fibers, and methods of
manufacture
Abstract
A laminated panel-type structure particularly suited for vehicle
interior applications such as headliners and door panels has a
multiple denier polyester fiber core and randomly oriented
structural reinforcing fibers. The laminated structure has superior
sound attenuation properties resulting from a core of intertwined
polyester fibers of differing deniers, with preferably relatively
larger denier fibers on exterior areas of the core and some
bicomponent fibers, short non-woven reinforcing fiber strands which
are randomly attached and intertwined with the core on opposing
major sides of the core, an impervious polymer film with a low melt
layer which retains the reinforcing fibers against one side of the
core and is attached to a scrim layer, and a polymer web on an
opposite side of the core which retains the reinforcing fiber
strands on the opposing major side of the core and to which a cover
stock is applied. The invention further includes a method of
manufacturing the laminated structure wherein the various layers
are sequentially unfurled from spools, passed through nip rollers
at points of various subcombinations of materials and layers, the
reinforcing fiber strands are randomly distributed on to the
carrying layers from hoppers or directly from a fiber chopping
device, and the completed laminated structure is cut and
molded.
Inventors: |
Fletemier, Todd; (Gowen,
MI) ; Ette, Robert; (O'Fallon, MI) ; Long,
Richard; (Lincoln Park, MI) |
Correspondence
Address: |
CALFEE HALTER & GISWOLD, LLP
800 SUPERIOR AVENUE
SUITE 1400
CLEVELAND
OH
44114
US
|
Family ID: |
22558121 |
Appl. No.: |
09/729232 |
Filed: |
December 4, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09729232 |
Dec 4, 2000 |
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09156106 |
Sep 18, 1998 |
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6156682 |
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Current U.S.
Class: |
442/35 ; 442/361;
442/394 |
Current CPC
Class: |
B32B 2260/021 20130101;
B32B 5/06 20130101; B29L 2031/3005 20130101; B32B 5/145 20130101;
B32B 2307/102 20130101; B32B 2451/00 20130101; Y10T 428/24995
20150401; B32B 2605/003 20130101; B32B 5/26 20130101; B32B 2255/26
20130101; B32B 2262/101 20130101; B32B 2262/0276 20130101; B32B
2305/20 20130101; Y10T 442/637 20150401; B32B 2255/02 20130101;
B32B 2419/00 20130101; B32B 2398/10 20130101; Y10T 442/159
20150401; B32B 5/022 20130101; B32B 5/08 20130101; B32B 7/12
20130101; B32B 2307/7265 20130101; B32B 5/10 20130101; B32B 37/226
20130101; B32B 2262/0261 20130101; Y10T 442/668 20150401; Y10T
442/674 20150401; B32B 2262/12 20130101; B32B 2607/00 20130101;
Y10T 442/659 20150401; B29C 43/203 20130101; B32B 2262/14 20130101;
B32B 2262/0253 20130101; Y10T 442/2861 20150401; B32B 2305/22
20130101; B32B 2307/546 20130101; B32B 2037/243 20130101; B32B
37/24 20130101; B32B 27/00 20130101; B32B 2260/046 20130101; Y10T
442/643 20150401 |
Class at
Publication: |
442/35 ; 442/361;
442/394 |
International
Class: |
B32B 005/26; D04H
003/00 |
Claims
What is claimed is:
1. A laminate structure comprising: a core of a combination of
non-woven polyester fibers having dissimilar deniers, a thermoset
resin in contact with the core, strands of non-woven structural
reinforcing fibers randomly adhered to opposing sides of the core
by contact with the resin, a polymer web laid over the reinforcing
fibers on one side of the core, and a face cloth laid over the
polymer web, an impervious polymer film laid over the reinforcing
fibers on an opposite side of the core, and a scrim layer laid over
the polymer film.
2. The laminate structure of claim 1 wherein the polyester fibers
of the core have combined deniers in a range of approximately 0.1
to 100.
3. The laminate structure of claim 1 wherein the polyester fibers
of dissimilar deniers of the core are randomly intertwined, and a
greater number of relatively small denier fibers than relatively
large denier fibers.
4. The laminate structure of claim 3 wherein the core comprises
layers of polyester fibers of dissimilar deniers, including an
internal layer of relatively small denier fibers, and an outer
layer of relatively larger density fibers.
5. The laminate structure of claim 1 wherein the core further
comprises bicomponent fibers which partially melt when heated.
6. The laminate structure of claim 5 wherein the bicomponent fibers
are blended with a layer of fibers having a denier which is larger
than a denier of the bicomponent fibers.
7. The laminate structure of claim 1 wherein the polyester fibers
of the core are bicomponent fibers which partially melt when
heated.
8. The laminate structure of claim 1 wherein the reinforcing fibers
are chopped from rovings to lengths in an approximate range of 1 to
4 inches.
9. The laminate structure of claim 1 wherein at least some of the
reinforcing fibers are intertwined with the polyester fibers of the
core.
10. The laminate structure of claim 1 wherein the reinforcing
fibers are glass fibers.
11. The laminate structure of claim 1 wherein the polymer web laid
over the reinforcing fibers on one side of the core has a melting
temperature which is lower than a melting temperature of the fibers
of the core.
12. The laminate structure of claim 1 wherein the impervious
polymer film laid over the reinforcing fibers further comprises low
melt polymer outer layers with adhesive properties.
13. A laminate structure with enhanced sound absorption and
structural properties comprising: a central core having opposite
sides and made of a combination of intertwined polyester fibers
having differing deniers in an approximate range of 0.1 to 100, the
combined fibers arranged with the core to form a layer of fibers of
relatively small denier adjacent to a layer of fibers of relatively
large denier, a resin applied to the core, structural fibers
randomly attached to the opposite sides of the core by contact with
the resin, at least some of the structural fibers being intertwined
with the polyester fibers of the core, a low melt polymer web over
the structural fibers on one of the opposite sides of the core, and
a face cloth over the low melt polymer web, an impervious polymer
film over the structural fibers on an opposite side of the core,
and a scrim layer over the impervious polymer film.
14. The laminate structure of claim 13 wherein the central core
comprises polyester fibers of differing deniers in an approximate
range of 0.9 to 45.
15. The laminate structure of claim 13 wherein the polyester fibers
of the central core include at least some bicomponent fibers which
partially melt when heated.
16. The laminate structure of claim 15 wherein the bicomponent
fibers of the central core are located in outer regions of the core
near the opposite sides of the core.
17. The laminate structure of claim 13 wherein the polyester fibers
of the central core are arranged so that fibers of relatively large
denier are positioned closer to at least one of the sides of the
core than are fibers of relatively small denier.
18. The laminate structure of claim 13 wherein the resin applied to
the core is a thermoset resin.
19. The laminate structure of claim 13 wherein the structural
fibers randomly attached to the opposite sides of the central core
are glass fibers of lengths in an approximate range of 1 to 4
inches.
20. The laminate structure of claim 13 wherein the impervious
polymer film over the structural fibers on one side of the central
core further comprises outer layers with adhesive properties to
bond to the structural fibers and to the scrim layer.
21. A method of manufacturing a laminate structure which can be
molded into a relatively rigid structure and which is effective at
absorbing sound, the method comprising the steps of: providing a
fibrous core and applying a thermoset resin to the fibrous core,
providing a polymer film which has a melting temperature less than
a melting temperature of the fibrous core adjacent to the fibrous
core, putting a plurality of reinforcing non-woven fiber strands
into contact with the polymer film and a first side of the fibrous
core, positioning the fibrous core containing a plurality of
intertwined polyester fibers of differing denier with a thermoset
resin applied to the fibrous core in contact with the plurality of
reinforcing non-woven fiber strands, putting a plurality of
reinforcing non-woven fiber strands into contact with a second side
of the fibrous core generally opposite to the first side, applying
a polymer web over the fiber strands applied to the second side of
the fibrous core, and applying a cover stock to the polymer
web.
22. The method of claim 21 wherein the fibrous core, polymer film,
and polymer web are placed in a generally co-planar arrangement by
being unfurled from spools, and the non-woven fiber strands are
placed in contact with the polymer film and fibrous core by random
distribution.
23. The method of claim 21 further comprising the steps of applying
the thermoset resin to the fibrous core by use of a resin
dispensing mechanism and a coating blade, passing the fibrous core
with thermoset resin through a first set of nip rollers prior to
contact of a first side of the fibrous core with the fiber
strands.
24. The method of claim 21 further comprising the step of passing
the fibrous core with the thermoset resin, fiber strands on the
first side of the fibrous core and polymer film, and fiber strands
and polymer web on the second side of the fibrous core through a
second set of nip rollers prior to application of the cover stock
to the second side of the fibrous core.
25. The method of claim 21 wherein the fiber strands are applied to
the polymer film and fibrous core by random distribution from a
chopping mechanism operative to chop fiber rovings into
strands.
26. A laminated fibrous and fiber-reinforced structure which can be
molded in a heated mold to a fixed shape, the structure having
sufficient structural strength to retain a fixed shape, and adapted
to absorb sound energy, the laminated structure comprising: a scrim
layer adapted to be placed substantially against a surface in
contact with the laminated structure, the scrim layer in contact on
one side with an impervious low melt polymer film having at least
first and second layers, the first layer being substantially
impervious, and the second layer having a relatively low melting
temperature whereby the second layer bonds with another material in
contact when heated, a first layer of structurally reinforcing
non-woven fiber strands placed in contact in a randomly oriented
arrangement with the polymer film on a side opposite to the scrim
layer, a generally planar core made of intertwined polyester fibers
in contact on one side with the first layer of fiber strands, a
second layer of structurally reinforcing non-woven fiber strands
placed in contact in a randomly oriented arrangement on a side of
the core opposite the first layer of fiber strands, a polymer web
in contact with the second layer of fiber strands, and a cover
stock in contact with the polymer web on a side opposite to the
fiber strands.
Description
FIELD OF THE INVENTION
1. The present invention pertains generally to molding of composite
materials including fibers and plastics and, more particularly, to
molding of structural and acoustical panels which include glass
fibers and thermosetting resins.
BACKGROUND OF THE INVENTION
2. Composite material panels-are used in many different
applications, including automobiles, airplanes, housing and
building construction. The properties sought in such panels are
strength, rigidity, sound absorption, and heat and moisture
resistance. One application of such panels which has been
especially challenging is automobile headliners and other
automotive interior panels. Many different types of laminates and
laminated composites have been tested and produced for use in
automobiles. Some headliners have a core of fiberglass fibers and a
polyester resin. Others have been manufactured from a core of open
cell polyurethane foam impregnated with a thermosetting resin, and
with a reinforcing layer of fiberglass. This type of construction
is inefficient in mass production, and has low acoustical
attenuation which is particularly undesirable for automobile
headliners.
3. Other approaches have been to form a laminate of fiber
reinforcing mat, such as a glass fiber mat on a fibrous core, and a
second reinforcing mat on the opposite side. The exposed surfaces
of the reinforcing mat are then coated with a resin and an outer
cover stock applied. This laminate is then formed to a desired
shape under heat and pressure, i.e., compression molding. Although
this type of structure has somewhat improved acoustical
characteristics, additional sound dampening is desired,
particularly for luxury automobiles.
4. In the prior art, the fibrous layers of the laminates consist of
fibers of relatively large and uniform denier or size. This
parameter is critical to sound attenuation properties, and fibers
of finer or smaller denier are required to achieve greater sound
absorption. However, fine denier fibers in the range of 1.2 or less
lack the resiliency required for retention of thermoformed shapes.
Although resiliency can be achieved by impregnating the fibers with
a resin, it is very difficult to impart an even distribution of
resin into a fibrous batt containing fine denier fibers. In the
prior art, extensive impregnation of the fibrous layers was not
required due to the presence of the stiff reinforcing layers.
Hence, given these trade-offs, a truly superior acoustical
dampening headliner of sufficient strength could not be
produced.
5. Although layers containing fiberglass have the desirable
characteristics of strength and some sound attenuation, they have
the undesirable traits of reflecting sound when made very hard or
dense. Fiberglass, particularly in woven mat form, is also
difficult to handle and is a known skin irritant. Because the
production of headliners and similar panels using fiberglass is
most commonly done manually, this is a significant problem which
has not been addressed. Alternative fibers, natural and synthetic,
have not been developed to be both cost effective and have strength
comparable to glass.
SUMMARY OF THE PRESENT INVENTION
6. The present invention overcomes these and other disadvantages of
the prior art, by providing a composite material laminated
structure which has all of the desired physical properties, and an
improved method of manufacture. In accordance with one aspect of
the invention, there is provided a laminated structure having a
core of polymeric fibers, a thermosetting resin impregnated into
the core, and individual chopped fibers randomly applied to
opposite sides of the core layer. A decorative layer is applied to
an exterior side of the laminate, and an impervious film and finish
scrim is applied to the opposite side of the core. The polymeric
fibers of the core are bonded together by a thermoplastic binder
system. A preferred method of bonding the fibers together is by a
bicomponent fiber, in which an outer layer of fibers is a low melt
temperature polymer, and an inner core layer of fibers is a polymer
with a relatively higher melt temperature.
7. In accordance with another aspect of the invention, there is
provided a laminate structure with enhanced sound absorption and
structural properties having a central core having opposite sides
and made of a combination of intertwined polyester fibers having
differing deniers in an approximate range of 0.1 to 100, the
combined fibers arranged with the core to form a layer of fibers of
relatively small denier adjacent to a layer of fibers of relatively
large denier, a resin applied to the core, structural fibers
randomly attached to the opposite sides of the core by contact with
the resin, at least some of the structural fibers being intertwined
with the polyester fibers of the core, a low melt polymer web over
the structural fibers on one of the opposite sides of the core, and
a face cloth over the low melt polymer web, an impervious polymer
film over the structural fibers on an opposite side of the core,
and a scrim layer over the impervious polymer film.
8. And in accordance with another aspect of the invention there is
provided a method of manufacturing a laminate structure which can
be molded into a relatively rigid structure and which is effective
at absorbing sound, the method including the steps of applying a
thermoset resin to the fibrous core, providing a polymer film which
has a melting temperature less than a melting temperature of the
fibrous core adjacent to the fibrous core, putting a plurality of
reinforcing non-woven fiber strands into contact with the polymer
film and a first side of the fibrous core, positioning a fibrous
core containing a plurality of intertwined polyester fibers of
differing denier with a thermoset resin applied to the fibrous core
in contact with the plurality of reinforcing non-woven fiber
strands, putting a plurality of reinforcing non-woven fiber strands
into contact with a second side of the fibrous core generally
opposite to the first side, applying a polymer web over the fiber
strands applied to the second side of the fibrous core, and
applying a cover stock to the polymer web.
9. These and other aspects of the invention are herein described in
particularized detail with reference to the accompanying
Figures.
BRIEF DESCRIPTION OF THE FIGURES
10. In the accompanying Figures:
11. FIGS. 1 and 2 are schematic representations of the laminated
structure of the invention, and
12. FIG. 3 is a schematic representation of a manufacturing set-up
to produce the laminated structure of the invention in accordance
with the method of manufacture of the invention.
DETAILED DESCRIPTION OF PREFERRED AND ALTERNATE EMBODIMENTS
13. As schematically represented in FIG. 1, the invention includes
a laminate, collectively referenced at 10, made up of combined
materials including a core 12 made of non-woven randomly
intertwined polymeric staple fibers of differing deniers (or
fineness as determined by weight per unit length) per filament,
such as for example 0.9, 4.0, 15 and 45, and generally in a wide
range from 0.1 to 100. Although these particular denier values are
given as examples, the invention is not limited to these values.
The more significant factor is that the deniers are combined in a
widely varying range which has been determined by the inventors to
provide the desired mechanical, bonding and acoustical properties.
In other words, it is the combination of fibers of different
deniers, rather than the specific denier values combined, which
improves the properties of the laminate 10. In particular, it has
been found that the fibers with relatively low deniers of, for
example, 0.9, contribute substantially to the increased sound
absorption of the core 12, and therefore in a preferred embodiment
a substantial percentage of the fibers of the core are of
relatively small denier such as 0.9.
14. The fibers range in length from approximately 0.5 inches to 3.0
inches, although other lengths may be used. The fibers are blended
with a bicomponent fiber, such as , which is utilized to effect
adherence between the individual fibers when the core is combined
with other layers of the laminate. As used herein, the term
"bicomponent" generally refers to a fibers having an outer layer or
sheath with a melting temperature which is relatively lower than a
melting temperature of a core. This characteristic allows the
fibers to bond to adjacent fibers or other materials in a thermal
formation process, without altering the desired physical properties
of the fiber core. The percentage content of the bicomponent fiber
ranges from 10 to 100, and is preferably in the range of 40
percent.
15. The fibers of the core 12 are initially held together in for
example a mat form by being intertwined by conventional textile
blending equipment such as carding, needling, air laying or
garnetting. The particular method of formation of the combined
fibers in a mat form is selected to preferably produce a loft of
approximately 150% of the finished part thickness for use in the
laminate manufacturing process described herein.
16. It has further been discovered that the sound absorption of the
laminate 10 is further enhanced by creating a dual density/denier
core 120, schematically depicted in FIG. 2, which can be used in
place of a single fiber denier core 12. The core 120 includes a
sublayer 121 which includes relatively fine denier fiber,
preferably 0.9 denier, blended with, for example 15 denier fibers
and bicomponent fibers such as polyethylene terephthalate (PET). A
second sublayer 122 adjacent sublayer 121 (and/or on both sides of
layer 121 as shown) has generally larger fibers, such as for
example 15 denier blended with 45 denier and bicomponent fibers
creates a dual density/dual denier laminate core. The core 120 can
be needled to impart sufficient strength, and/or passed through an
oven to melt the outermost bicomponent fibers to give the core
structural rigidity and strength.
17. The combined fibers of different deniers and the bicomponent
fibers are more readily and effectively intertwined by needling
than is a mass of fibers of the same denier. Because the fibers are
adequately mechanically interconnected, there is no need to
impregnate the core 12 with a binding agent such as a resin in
order to form the core 12. However, in order to attach the other
layers of the laminate 10 to the core 12, the individual fibers
which malke up the core 12 are preferably a thermoplastic polymer,
such as polyethylene terephthalate (PET). These fibers may be
virgin or manufactured from recycled product. The fibers are
preferably crimped at a rate of from 1 to 30 crimps per inch,
although straight fibers may also be used. Internal bonding of the
fibers of the core 12 occurs when the fibers are heated by forced
air or by a fixed heat source such as a heated mold.
18. Referring again to FIG. 1, the laminate 10 further includes
structural reinforcement layers 14 and 16 which are fiber pieces
chopped from rovings, preferably glass fiber rovings, having from
30 to 400 strands, with a strand thickness in an approximate range
of 5 to 25 microns, and a specific gravity of approximately 2.5. In
a manufacturing process further described below, the strands are
fed into a glass chopper and cut to a length of between
approximately 1 to 4 inches. After the fibers are fed through the
chopper, they are allowed to fall at random onto the sides of the
core 12 as further described below.
19. Alternatively, the reinforcement layers 14 and 16 may be
constructed of continuous strands of continuous mineral fibers,
such as Basalt. The individual strands would preferably have a
thickness in an approximate range of 9 to 16 microns and specific
gravity of approximately 2.9. The fibers would be processed
(chopped) in a manner similar to the glass fiber rovings, with
about 3 to 300 individual strands per roving.
20. With reference to FIG. 3, a method of manufacturing the
laminate 10 is described. In an assembly line set-up indicated
generally at 100, the core 12 (or 120) is fed from a spool 101
through a series of feed rollers 102 past a resin applicator 104 at
which resin, supplied from a resin supply reservoir/dispenser 106,
is applied to the major surfaces of the core 12. The core with
resin applied then passes through upper and lower press rollers
103, and upper and lower guide rollers 105. Fiber rovings, such as
relatively short individual glass fibers, and also referred to as
"strands" 14 are supplied from roving reservoir 108 and randomly
applied to polymer film layer 18, preferably in a random
gravity-fed fashion such as sprinkled from an agitator tray or
chopper 109 positioned over the core as it passes by.
Alternatively, the fiber strands may be applied by manual
distribution from a container, or cut from continuous strands
directly above the core and allowed to fall randomly upon the core.
The fiber strand rovings only partially adhere to the core upon
contact with the resin applied to the surfaces of the core. As the
resin-carrying core 12 passes lower guide roller 105, the lower
side of the core comes into contact with the randomly oriented
strands 14 carried on the upper surface of layer 18. Thereafter,
reinforcing strands 16 are randomly applied to the upper side of
the core 12 from chopper 109.
21. The low melt polymer web layer 19, fed from spool 110, is then
applied over strands 16 on the upper (interior) side of core 12,
and passes through nip rollers 111. The primary purpose of the web
layers 18 and 19 is to contain the individual strands of the fibers
of layers 14 and 16 until the laminate is nipped about the
perimeter or otherwise self-contained such as by insertion into a
mold. Therefore, it is desirable that the web layers 18 and 19 melt
out in the forming process so as not to affect the structural
properties of the completed laminate. A preferred material for the
web layers 18 and 19 is a polyamide web, such as Spunfab
PA1008.
22. As shown in FIG. 1, the web layer 18 is preferably a
multi-layer impervious low melt polymer film applied to the inner
side of the core 12, between the chopped fiber strands and an
internal scrim layer 20. The purpose of web layer 18 is to prevent
any resin from reaching the scrim layer 20 and to thereby retain
the resin within the laminate. A preferred material for web layer
18 has a polyethylene core, and outer layers of a polymer with a
low melting point which bonds by melting to the scrim layer 20 on
one side, and to the fiber strands of layer 14 on the other side.
The scrim layer 20 is constructed from either a woven or
needled/punched product and facilitates bonding and installation of
the laminate 10, for example in the interior of a vehicle.
23. After the web 19 is applied, a cover stock 22 is applied from
spool 23 over web 19 to complete the laminate structure, after
which it may be cut and molded as shown. The cover stock 22 is
decorative and covers the exposed surface of the laminate 10, such
as the interior side of an automobile headliner. It is typically
constructed of a knit textile with a polymer base, such as nylon or
polyester. The cured resin serves to bond the cover stock 22 to the
fiber reinforcing layer. In installations where a soft feel to the
cover stock 22 is desired, a layer of foam may be pre-attached to
the internal side of the cover stock.
24. The resin used to impregnate the core 12 is an elastomeric
thermosetting resin, preferably a curable urethane of approximately
100 parts by weight of a polyol having three or four hydroxly
groups, 70 to 95 parts by weight of an isocyanate compound having
at least two reactive isocyanate groups, with diphenelmethane
diisocyanate (MDI) being preferred; approximately 0.00 to 0.15
parts of a catalyst such as an amine or metal complex;
approximately 0 to 20 parts of an appropriate blowing agent; and 0
to 5 parts of a suitable surfactant. An example of one type of
suitable resin system is a blend of Voranl 446 and Papi 4027 from
Dow Chemical Co.; Dabco from Air Products, Inc.; water, and DC-193
from Dow Corning. The amount of resin applied varies according to
the density of the fiber core. A preferred approximate ratio of
resin to fiber density is 1.2 to 1.
25. Referring again to FIG. 3, the scrim layer 20 and impervious
film layer 18 are unwound in unison from respective spools and fed
under roving choppers 109 for random distribution of the chopped
fiber strands 14. The core 12 is fed at the same rate as the scrim
layer 20 and the impervious film layer 18. The resin is applied by
continuous coating such as roll coating, knife over roll, spray or
curtain. A preferred method of coating for manufacture of the
described laminate structure is to apply the resin to a coater
blade 104 from the resin reservoir or nozzle 106 at a rate
sufficient to maintain a small layer of resin on the blade. The
tangential application angle of the blade relative to the direction
of travel of the core 12 is critical to the amount of resin
imparted into the core 12. The preferred application angle range is
from 10 degrees to 80 degrees, with 35 degrees the most preferred
angle.
26. The distance from the coating blade 104 to the top nip roller
103 is also critical to the resin impregnation of the core 12. This
distance ranges from 10% to 100% of the thickness of the core, with
40% the most preferred distance. The coated core is then fed
through the upper and lower nip rollers 103 to evenly distribute
the resin into the core. The gap in the nip rollers is adjusted to
adequately drive the resin into the pad. This gap ranges from 1% of
the core thickness to 90% of the core thickness.
27. Subsequent to the nip process the core 12 is laid onto the
randomly oriented fiber strands 14 previously applied to film layer
18. The product then passes under the second fiber chopper 109
where the fiber rovinas 16 are cut to length and randomly
distributed onto the impregnated core. The fibers are oriented to
the plane of the core 12 at an infinite number of angles. Some of
the fibers become intertwined with the core 12.
28. The low melt polymer web 19 is laid onto the chopped fibers and
the product is then fed into a second set of nip rollers 111. The
second set of nip rollers serves to coat the resin around the fiber
reinforcing strands. After the nip, the cover stock 22 is unrolled
onto the pad. The product is then cut to length and can be fed into
a mold (not shown) having the desired contours to which the
laminate is to be formed. As is known in the art, the mold is
heated to a temperature sufficient to set the thermosetting resin,
and sufficient to melt the polymer layers of the polymer web 19.
Pressure is applied to compress the laminate to conform to the
internal configuration of the mold.
29. Although the invention has been shown and described with
reference to certain preferred and alternate embodiments. The
invention is not limited to these specific embodiments. Minor
variations and insubstantial differences in the various
combinations of materials and methods of application may occur to
those of ordinary skill in the art while remaining within the scope
of the invention as claimed and equivalents.
* * * * *