Note: Descriptions are shown in the official language in which they were submitted.
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CHOPPED FIBERGLASS LAMINATE FOR AUTOMOTIVE HEADLINERS AND
METHOD OF FABRICATION
CROSS-REFERENCE TO RELATED APPLICATION
This is a continuation-in-part of pending U.S. application Serial No.
09/387,813
filed on September 1, 1999.
1 o BACKGROUND OF THE INVENTION
This invention relates to a chopped fiberglass trilaminate structure and a
method
of manufacture, and more particularly to a chopped fiberglass laminate having
improved
elongation for use in forming moldable headliners made from such structures
for motor
vehicles.
Prior art constructions of moldable headliners for trucks and automotive
vehicles
generally included a phenolic saturated fiberglass mat molded into a shell. In
a secondary
step, a cloth decorative outer layer, usually of a nylon tricot fabric backed
with a 3 mm
foam layer is attached to the shell. The foam helps to hide imperfections in
the fiberglass
2 o shell.
The automotive industry recently has moved away from this construction to
accepted European technology. This technology involves use of a multi-layered
composite including a foam core and two outer layers of chopped fiberglass
surrounding
the foam core. The fiberglass is either chopped in place or provided in mat
form and
2 5 generally includes fiberglass yarns in tow form cut to about 1.27 to 10.16
cm (1/2 " to 4")
long. This tri-laminate is saturated with an isocyanate resin which bonds the
layers
together during the molding process which forms the part into a shape to fit
into a specific
vehicle. The fiberglass layers on either side of the foam core are included to
impart
proper stiffness to the headliner part.
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The European triplex construction is generally further sandwiched between
outer
film layers. These film layers act as burners to prevent the liquid isocyanate
resin from
penetrating through the top layer which is the decorative fabric. Similarly,
the film layer
on the back of the part prevents the isocyanate from penetrating the backing
mold release
layer and contaminating the mold. If the liquid adhesive bleeds through the
decorative
fabric, it would be visible and a cause for rejection of the part, or it could
cause sticking
or attachment of the back side of the part to the mold.
There are ongoing efforts in the automotive industry to provide moldable
headliner components which exhibit increased elongation in both the machine
and
1 o transverse directions and to facilitate fabrication into severe curves and
offsets during the
curing process. Conventional glass fiber layers added to improve stiffening of
the
finished headliner generally are brittle thereby limiting the ultimate shape
of the finished
product.
One example of a commercial sound absorbing laminate is shown in U.S. Patent
No. 4,828,910 to Haussling. Here the laminate structure includes a reinforcing
porous
mat of chopped glass fiber integrally bonded to a resilient fibrous butt. A
decorative
cover sheet covers the exposed or exterior surface of the reinforcing mat all
bonded
together by a thermoset resin binder. The reinforcing mats sandwiching the
fibrous butt
are of glass fibers bonded together by a thermoformable resin to impart the
required
2 0 stiffness to the finished headliner. Finally, a porous cloth scrim as a
release layer is
adhesively secured to the back of the reinforcing mat by the thermoset resin
coating the
mat.
Another type of molded automobile headliner is shown in U. S. Patent No.
4,840,832 to Weinle, et al. Here, the headliner is formed from a butt of
polymeric fibers
2 5 including at least a portion of potentially adhesive fibers. The finished
headliner is
characterized by being of a highly deformable resilient construction which
facilitates
installation in the vehicle. The fibers in the butt are bonded together at a
multiplicity of
locations which impart a self supporting molded rigidity allowing the
headliner to retain
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its shape when installed. A flexible foam layer is adhered to one surface of
the flexible
batt and the outer textile fabric is bonded to the foam layer.
Romesberg, et al. in U.S. Patents No. 5,486,256 and No. 5,582,906 disclose a
typical foam core I-beam type headliner having a layer of chopped fiberglass
on both
sides of a central foam core. The chopped fiberglass is applied at a first
glass chopping
stations onto a belt of adhesive film which becomes the back fiberglass layer
and deposits
a second fiberglass layer onto the front of the foam layer at a second glass
chopping
station. A wet adhesive is then applied onto the second fiberglass layer and a
decorative
fabric applied to the adhesive prior to molding.
1 o U.S. Patent No. 5,591,289 to Souders, et al describes another headliner
based on a
fibrous batt including binder fibers coated with a thermoset resin for
imparting stiffness to
the part. In U.S. Patent No. 5,660,908 to Kelman, et al. A 100% polyethylene
terephthalate (PET) headliner is formed from a fibrous batt having a plurality
of
impressions which are filled with PET filler and bonded to a PET scrim for
imparting
additional stiffness.
While the available constructions produce suitable composites, constructions
that
include glass fibers for stiffening the final product remain difficult to
mold. Accordingly,
it is desirable to provide a chopped fiberglass laminate for a moldable
headliner which
will provide a composite for molding having at least about 30 per cent
elongation in both
2 o the machine and transverse directions, allow excellent conforming to deep-
draw areas
when molding and provide the required stiffness in the final headliner
product.
SUMMARY OF THE INVENTION
2 5 Generally speaking, in accordance with the invention, a chopped fiberglass
laminate for fabricating moldable structures and methods of fabrication of the
laminate
and headliner including the laminate are provided. The chopped fiberglass
laminate is
formed by feeding a continuous nonwoven scrim of fine denier synthetic fiber
and a
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non-porous barrier film through nip rollers. Chopped fiberglass and adhesive
are
deposited on the moving barrier film and nonwoven scrim which is then heated
in an
oven, passed through pressure nip rollers, cooled and then wound in roll form
for
transport and use.
The chopped fiberglass laminate possesses elongation properties at break
exceeding about 30 to 40% in both the machine and transverse directions. The
fine
denier synthetic fiber utilized in the nonwoven scrim is a spunbond fiber
having a
denier of between about 1.8 to 2.2 in order to impart the desired elongation
properties.
A headliner composite is formed by combining the fiberglass laminate with a
1 o foam layer on the fiberglass surface, an additional fiberglass layer is
disposed on the
opposite surface of the foam and a decorative fabric which may include a foam
backing is placed on the exposed fiberglass surface. This headliner composite
is then
ready for molding. The high elongation properties of the chopped fiberglass
laminate
provide excellent conformability to deep-draw areas in the mold.
Accordingly, it is an object of the invention to provide a scrim/barrier
film/chopped fiberglass containing laminate structure having improved
elongation
properties.
Another object of the invention is to provide an improved chopped fiberglass
containing laminate including a nonwoven scrim formed of fine denier spunbond
2 0 synthetic fibers.
A further object of the invention is to provide an improved chopped fiberglass
containing laminate including a nonwoven scrim formed of fine denier spunbond
polyester fibers of about 1.8 to 2.2 denier.
Yet another object of the invention is to provide an improved chopped
fiberglass
2 5 containing laminate including a thermoplastic barrier film for adhering
the chopped
fiberglass thereto and providing a non-porous barner to prevent mold
contamination.
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Yet a further object of the invention is to provide a method for fabricating a
chopped fiberglass containing laminate with elongation at break exceeding 30
to 40%
in both the machine and transverse directions and energy to break less than 20
lbf in. in
either direction.
Still a further object of the invention is to provide a method for forming the
nonwoven scrim/barrier film/chopped fiberglass laminate which can be formed
into a
roll or sheeted for easy storage and transport prior to being combined to form
an
automotive headliner composite.
Still another object of the invention is to provide an apparatus for forming a
1 o nonwoven scrim/barner film/chopped fiberglass laminate which can be stored
in roll or
sheet form.
Still other objects and advantages of the invention all or in part be obvious
and all
in part be apparent from the specification.
The invention accordingly comprises several steps and the relation of one or
more
of such steps with respect to each of the others, and the products which
possess the
characteristics, properties and relation of constituents (components), all as
exemplified in
the detailed disclosure hereinafter said forth, and the scope of the invention
will be
indicated in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
For a fuller understanding of the invention, references is had to the
following
description taken in connection with the accompanying drawings, in which:
FIG. 1 is a perspective view from above a vehicle of a headliner including a
chopped fiberglass/barner film/scrim laminate constructed and arranged in
accordance
2 5 with the invention;
FIG. 2 is a partial cross-sectional view of the chopped fiberglass containing
laminate constructed and arranged in accordance with the invention;
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FIG. 3 is a schematic view illustrating the process; steps and equipment
utilized in
accordance with the invention to fabricate the laminate of FIG. 2;
FIG. 4 is a partial cross-sectional view of the headliner components of FIG. 1
showing how the laminate and additional components are molded; and
FIG. 5 is an enlarged partial sectional view of the headliner of FIG. 1 taken
along
line 5-5.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
1 o A headliner 11 constructed and arranged in accordance with the invention
is
shown mounted to the underside of the roof of an automobile vehicle 12 in FIG.
1.
Headliner 11 may be fastened in a number of conventional ways at points 13
well known
in the art and not described herein. These methods include adhesives, use of
velcro
attachments, fastener strips and various types of moldings. Headliner 11 may
be molded
in non-uniform thickness as shown in FIG. 2. Headliner 11 may also include
various
regions 14 for visors and a cut out region 16 for a dome lamp and a large open
region 17
for a sunroof in a vehicle roof 15.
FIG. 2 illustrates in detailed cross-section the components of a chopped
fiberglass
containing laminate 21 constructed and arranged in accordance with the
invention.
2 0 Laminate 21 includes a nonwoven scrim 22, a burner film 23 and a chopped
fiberglass
layer 24 including a thermoplastic adhesive 26. When assembled, nonwoven scrim
22
will be the back surface of headliner 11 adjacent to metal vehicle roof 18.
Laminate 21
formed from nonwoven scrim 22, barrier film 23 and chopped fiberglass layer 24
in
accordance with the process illustrated in FIG. 3 will provide significant
advantages.
2 5 These include a laminate that will impart stiffening properties when used
as a component
in an automotive headliner, eliminate possible resin bleed-through during post-
lamination
molding which often occurs, and have sufficient elongation properties that
allows
excellent conforming to deep-draw areas when molding.
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Nonwoven scrim 22 used in forming laminate 21 is formed of a spunbond
polyester fiber and has a weight between about 0.50-1.75 oz/yd2 (17-60 g/m2).
Preferably,
nonwoven scrim 22 has a weight between about 0.8-1.2 oz/yd2 (27-41 g/m2) and
is 100%
polyethylene terephthalate (generally referred to as polyester or PET) fiber.
In the
exemplary embodiment, nonwoven scrim is a 100% polyester spunbond fiber
weighing
1.00 oz/yd2 (34 g/m2)
The polyester fiber used to make nonwoven scrim 22 is a spunbond PET fiber
having a denier of between about 1.8-2.2. Utilizing a fiber with this fine
denier, assists in
providing nonwoven scrim 22 with non-bleed-through properties within the
laminate. If
1 o coarser fibers are used to make a nonwoven scrim of the same weight, there
is less
surface area coverage in the nonwoven material. This decreased surface area
would be
accounted for in the larger diameter/denier fiber. Thus, fibers of between 1.8-
2.2 denier
increase the surface area which in turn decreases the permeability of nonwoven
scrim 22.
This reduction in permeability prevents barrier film 23 used in laminate 21
from bleeding
through scrim 22 and inadvertently bonding to a molder's tool during thermal
forming
where tool temperatures are generally above the barrier film's melt
temperature.
Nonwoven scrim 22 is selected to have suitable elongation in both the machine
direction and cross direction so that laminate 21 will have the desired
elongation
properties. Preferably, nonwoven scrim is selected to have between about 30 to
60
2 o percent stretch in both the machine and cross machine directions. Most
preferably, the
break properties exceed about 35 to 45 percent and most preferably about 40
percent
elongation.
In addition to the elongation to break, the tensile strength is also an
important
physical property. Nonwoven scrim 22 is selected so that the tensile strength
is below
2 5 about 7 to 10 pounds of force in the machine direction and below about 4
to 7 pounds in
the cross direction. In the preferred embodiments of the invention, nonwoven
scrim 22
has a tensile strength below about 8 pounds of force in the machine direction
and below
about 4 to 5 pounds of force in the cross or transverse direction.
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In addition to the tensile strength, the energy to break is also an important
physical
characteristic of nonwoven scrim 22. The energy to break corresponds to the
area under a
stress-strain curve, and thus represents the toughness of the material.
Accordingly, if the
energy to break is too high, it will require too much energy to fill the deep
draw cavity
with laminate 21 tearing or bridging in the headliner mold and not be suitable
for the
desired end use of laminate 21. The energy to break of a suitable nonwoven
scrim 22 is
preferably below about 8 to 12 pound inches in the machine direction and below
about 4
to 7 pound inches in the cross direction.
Both the elongation and energy to break properties are determined under a
1 o modified version of ASTM D 5035-95 Test Method For Break Force And
Elongation Of
Textile Fabrics (Strip Test).
Finally, nonwoven scrim 22 is selected so that it can withstand mold
temperatures
which are generally in the range of about 130 to 140°C (about 270-
285°F). A spunbond
polyester scrim having the characteristics described above generally softens
at a
temperature of about 250-260°C. Thus, the integrity of nonwoven scrim
22 should not be
altered substantially when forming an automotive headliner with laminate 21 in
accordance the invention.
Barrier film 23 is formed of a thermoplastic film that may be formed of one or
more layers. There are a wide variety of such barrier films available which
are suitable
2 o for use in laminate 21. A particular film chosen will depend on the
headliner
manufacturer's tool and the molding conditions such as tool temperature and
dwell time.
Whether a high heat stable film is used or a low heat stable film is used, the
thickness of the film should be between about 1.0-2.0 mil (0.001-0.002").
Preferably, the
thickness of barrier film 23 should be about 1.5 mil (0.0015"). The selected
barrier film
2 5 also has an effect on the elongation properties of the final composite and
must be chosen
according to the tool conditions and final composite stretch desired and
required
temperature resistance.
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Barrier film 23 may be a polyolefin film or may be a blend chemistry and can
be
formed of a single or multilayer structure. As noted, a wide selection of
barrier films is
suitable. Specific examples include Dow Intergal 925 film which is a tri-layer
film
having a core layer heat stable up to about 165°C (330°F) and
having outer polyethylene
adhesive layers which are heat activated at temperatures of about 127°C
(260°F).
Alternatively, when such a high heat stable film is not required, a polyolefin
film, such as
Dow Intergal 909 or 906 can be used. The activation point of these films is
below the
mold temperatures and activate at temperatures of about 100°C
(212°F).
Regardless of the particular film selected, barner film 23 should have a
tensile
1 o modulus (2% secant) between about 9,000-50,000 pounds/in2 before
lamination. Of
course, the choice of barrier film 23 will have an effect on the final
elongation properties
of laminate 21 and must be chosen according to molding conditions and stretch
desired of
laminate 21. In these cases, the tensile modulus (2% secant) is determine
using ASTM
test method ASTM D 882.
Barrier film 23 in accordance with the invention is nonporous and has a corona
treated surface. This assists in bonding barrier film 23 to nonwoven scrim 22.
The
corona surface treatment aids in achieving a bond between the two layers which
in turn
plays an important role in achieving the desired stretch properties of final
laminate 21.
Corona treated side of barner film 23 is laminated against nonwoven scrim 22.
2 0 Fiberglass layer 24 is formed by depositing chopped fiberglass on the
exposed
surface of barrier film 23. The fiberglass applied to barrier film 23 is
chopped to provide a
range of between about 30-200 g/mz of fiberglass with strands having a length
between
1.0-4.0 inches in length. Preferably, the length of the chopped rovings is
about 2.0 inches.
Chopped glass fibers are applied to barrier film in a random fashion and is
combined with
2 5 an anti-static chemical sizing agent to reduce static buildup at the glass
chopper.
Prior to completion of assembly of laminate 21, a thermoplastic adhesive is
applied onto the chopped fiberglass randomly. If a powder resin is used as in
the
illustrated embodiment, the particle size used can range from about 100-500
microns
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having an average of about 200-300 microns. The resin adhesive is
thermoplastic and can
be, for example polyethylene, polyester, polyamide, or ethylene vinyl acetate.
Generally,
the amount of thermoplastic adhesive applied ranges from about 0.15-1.00
oz/yd2 (5-43
g/m2). The actual amount of resin applied depends on the amount of fiberglass
deposited
on barrier film 23.
FIG. 3 illustrates the process steps and an apparatus 31 utilized to fabricate
laminate 21. Here, nonwoven scrim 22 wound on a scrim roll 32 at a scray 33
(Station 1)
is fed with the rough side down is fed under a film stand 34. Film stand 34
includes a
first film roll 36 and second film roller 37 (Station 2). In the embodiment
illustrated in
1 o FIG. 3, one or both of film rolls 37 and 38 may be utilized for feeding
barner film 23.
Two rolls allow for continuous feeding when one roll is empty, or for feeding
mufti-layer
barrier films for forming laminate 21.
Barrier film 23 is fed over a third nip roller station 38 (Station 3) and
nonwoven
scrim 22 is fed below nip rollers 38. Nonwoven scrim 22 and barrier film 23
are both fed
between a second pair of nip rollers 39 (Station 3) to form a loose barrier
film/nonwoven
scrim composite 27. Composite 27 is fed below a glass chopper dispenser 41
(Station) 4)
where chopped fiberglass in the desired quantity is deposited on the exposed
surface of
barner film 23. Composite 27 is then fed beneath a resin dispensing hopper 42
(Station
5) which deposits the desired amount of thermoplastic adhesive 26 onto chopped
2 o fiberglass layer 24 on barrier film 23.
When barner film 23 passes through second pair of nip rollers 39, it is
arranged so
that the corona treated surface will be laminated facing nonwoven scrim 22.
Nonwoven
scrim 22 typically has a characteristic flat or smooth side due to the spun
bond technology
used in its manufacture. In accordance with the invention, the method of
forming
2 5 laminate 21 includes arranging nonwoven scrim 22 at the scray so that the
smooth or flat
surface will bond to barrier film 23. Accordingly, in FIG. 3, the lower
surface of
nonwoven scrim 22 is the rough surface. It has been found that this
arrangement imparts
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reduced squeak properties in the final headliner which are advantageous to the
headliner
molder.
Resin and fiberglass/barrier film/nonwoven composite 27 is then fed through an
oven 43 (Station 6) where powder adhesive 26 and barrier film 23 is activated
by the heat.
Oven 43 may be of any suitable type, but configured so that heat is applied to
composite
27. In the preferred embodiment illustrated in FIG. 3, oven 43 includes a
number of
electric infrared heating elements 44 which are located on the upperside of
oven 43 to
apply heat to the fiberglass side of composite 27 only. There is no direct
heat being
applied from the bottom to nonwoven scrim 22 of composite 27.
1 o The oven heat is monitored by measuring the temperature of composite 27 as
it
exits oven 43. Depending on the particular burner film, fiberglass and resin
used, the
oven temperature is monitored so that a bond is achieved between nonwoven
scrim 22
and burner film 23. At the same time, thermoplastic adhesive 26 melts and
blends into
the chopped fiberglass laying on barrier film 23. If the operating temperature
of oven 43
exceeds the desired temperature, the burner film will be activated and bonded
too
strongly to nonwoven scrim 22 thereby jeopardizing the deep draw and high
stretch
properties of finished laminate 21. The primary objective is to provide
sufficient bond
between barrier film 23 and nonwoven scrim 22 so that delamination does not
occur
before composite 27 is molded by the headliner manufacturer.
2 o After thermoplastic adhesive 26 has been activated in oven 43 composite 27
is
laminated at a first nip roller 45 (Station 7) to form laminate 21. First nip
roller station 45
is maintained at a temperature just below room temperature and applies a
downward
pressure of between about 10-80 lbs/in2 to composite 27. Preferably, between
about 30-
40 lbs/inz pressure is applied, and most preferably about 20 lbs/in2 to form
laminate 21.
2 5 The actual pressure depends on the amount of fiberglass added at
fiberglass chopper 41
and the thickness deposited on the barrier film 23.
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If too much pressure is applied at first nip station 45 and the temperature of
oven
43 exceeds the activation temperature of barrier film 23, the nip roller
pressure will force
the fiberglass into barrier film 23 and cause pinholes therein. If this
occurs, the non-
bleed-through properties of barner film 23 would be lost. Use of a cool nip
roller at first
nip roller station 45 quickly solidifies thermoplastic adhesive 26 where
lamination occurs.
Laminate 21 is then further cooled at a cooling station 46. Cooling station 46
includes a first cooling roller 47 and a second cooling roller at 48. Laminate
21 passes
over first cooling roller 47 and under second cooling roller 48. Both rollers
47 and 48 are
maintained below room temperature. Cooling rollers further cool laminate 21
and provide
1 o a desired amount of tension between cooling station 46 and a final batch
roller 49 where
laminate 21 is wound (Station 9).
FX A MPT .F. 1
A laminate formed utilizing the apparatus and process described in connection
with FIG. 3 was evaluated. Evaluation was preformed by preparing a test
solution of
water, 1 % by weight nonionic wetting agent and 1 % by weight of any direct
dye. The
mixture includes the dye to provide easy visual evaluation of bleed-through
properties. A
sample of final laminate 21 is obtained at batch roller 49. Test solution is
then spread on
2 0 the chopped fiberglass side of laminate 21 using a piece of sponge. After
letting the
solution stand on laminate 21 for one minute, laminate 21 is turned over to
determine
whether the solution has bled through the layers.
Laminate 21 should not show any signs of solution bleed-through to the
nonwoven scrim side. A positive test, or appearance of the dye on nonwoven
scrim 22
2 5 indicates that there are holes produced in barrier film 23 during the
lamination process.
Finished laminate 21 was then tested for physical properties on a tensile
testing
machine with an Instron 4400 Series Tester. A total of at least 5 samples were
cut in the
machine direction and transverse direction. The samples were then dye cut into
a 1 " x 6"
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specimen side with the 6" length being the direction tested. This is a
modified version of
ASTM D 5035-95 Test Method For Break Force and Elongation of Textile Fabrics
(Strip
Test). An initial jaw gap of 1" over the chopped fiberglass length is used. If
a 2"
chopped fiberglass composite is produced the initial draw gap should be 3".
This is to
ensure that strands of chopped fiberglass will not be present in both the top
and bottom
testing jaw because this tends to cause inaccurate elongation results. Testing
speed was 12
yds/min. Final elongation at break, not elongation at peak load, in both the
machine
direction and transverse direction of the final laminate exceeded about 30-
40%. The
energy to break has been calculated to be below 20 lbf in. (This is not
calculated at the
1 o peak load, but at the actual break of the laminate.)
F.X A MPT .F 7
Fabrication of a headliner shown in FIG. 5 having an outer layer of a vinyl or
decorative fabric 28 backed with a thin foam to mask surface irregularities is
adhered to
the outer surface of a foam core 29 impregnated with a liquid resin, such as
an isocyanate
as is well known in the art, and a second layer of glass fibers therebetween.
The
components are assembled in the order described above and placed within a mold
S 1 and
closed as shown in FIG. 4. Mold S1 is heated to approximately 93° to
177°C (200°-
2 0 350°F) for 1-10 minutes and the thermoplastic resins bond the
layers together. On
removal and cooling of the composite from the mold, the various layers are
sufficiently
adhered to each other so that the part may be utilized as a sound absorbing
headliner in a
motor vehicle. An alternative method involves preheating the composite to
adhere the
various layers and shaping the final part using a cold mold.
2 5 By providing a nonwoven scrim/barrier film/chopped fiberglass deposit web
in
accordance with the invention, several advantages for the construction of
automotive
headliners are obtained. Use of a fine denier spun bond fiber having a density
in the
range of about 1.8-2.2 results in a composite having an elongation at break
exceeding
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about 30-40% in both the machine and transverse directions. The energy to
break is less
than about 20 lbf in. in both directions.
Improved elongation properties coupled with the low energy to break, allows
deep
draw to be obtained in addition to the absence of pinholes or punctures in the
barner film
preventing bleed-through of the burner film or resin.
It will thus be seen that the objects set forth above, among those made
apparent
from the preceding description, are efficiently attained and since certain
changes may be
made in carrying out the above method and in the article set forth without
departing from
the spirit and scope of the invention, it is intended that all matter
contained in the above
1 o description and shown in the accompanying drawings shall be interpreted as
illustrative
and not in a limiting sense.
It is also to be understood that the following claims are intended to cover
all of the
generic and specific features of the invention herein described and all
statements of the
scope of the invention which, as a matter of language, might be said to fall
there between.
Particularly, it is to be understood that in said claims, ingredients or
compounds
recited in the singular are intended to include compatible mixtures of such
ingredients
wherever the sense permits.
