Abstrict Laminate sheet materials having outer fabric layers and an intermediate
non-woven fiberfill layer are provided, which are particularly suitable
for use in making molded, one-piece, bra cups. The sheet materials
are uniformly pre-shrunk, and include fabric outer layers that are
securely rather than lightly bonded to an intermediate fiberfill
layer by amounts of adhesive that substantially penetrate the intermediate
layer.
Claims We claim:
1. A laminate composition suitable for molding into one-piece bra
cups, comprising oppositely disposed outer fabric layers and an
intermediate fiberfill layer of non-woven staple fibers disposed
therebetween, said layers being held together with a separate and
distinct adhesive composition which substantially penetrates said
intermediate layer to securely bond said outer fabric layers to
said intermediate fiberfill layer, said outer fabric layers and
said intermediate fiberfill layer comprising fiber materials which
shrink at approximately the same rate upon application of heat and
pressure.
2. The laminate composition of claim 1 wherein said laminate composition
is uniformly pre-shrunk prior to complete drying of said adhesive
composition.
3. The laminate composition of claim 1 wherein said adhesive composition
penetrates said intermediate layer to a depth of between about 1/3
and 1/2 the overall thickness of said intermediate layer on each
side of said intermediate layer.
4. The laminate composition of claim 3 wherein said outer fabric
layers comprise polyester fibers having deniers in the range of
about 20 to 70 and said intermediate fiberfill layer comprises
random, non-woven, staple polyester fibers having average fiber
lengths in the range of about 1 to 2 inches.
5. The laminate composition of claim 1 wherein said adhesive composition
is an aqueous dispersion or emulsion of a carboxylic acrylic polymer.
6. A molded bra cup made from the laminate composition of claim
1.
7. A laminate composition suitable for molding into one-piece bra
cups, comprising a first outer fabric layer and an intermediate
fiberfill layer of non-woven staple fibers secured to said outer
fabric layer, said layers being held together with an adhesive composition
which penetrates said intermediate layer to a depth of between about
1/3 and 1/2 the overall thickness of said intermediate layer, said
outer fabric layer comprising polyester fibers having deniers in
the range of about 20 to 70 and said intermediate fiberfill layer
comprising random, non-woven, staple polyester fibers having average
fiber lengths in the range of about 1 to 2 inches, whereby upon
application of heat and pressure said fabric layer and fiberfill
layer shrink at approximately the same rate.
8. A molded bra cup made from the laminate composition of claim
7 wherein a second outer fabric layer is secured to said intermediate
fiberfill layer opposite said first outer fabric layer.
Description BACKGROUND AND SUMMARY OF THE INVENTION
This invention relates to laminated sheet materials, and to specific
laminate materials which have been found to be particularly useful
in making molded, one-piece, non-stitched bra cups.
At present, the bra cup portion of brassieres, as they are currently
manufactured, are made in a multi-step process that requires, among
other things, that two or more pieces of laminated fabric be separately
molded, sewn together to form a completed bra cup, and then integrated
into a finished brassiere. Such a manufacturing technique involves
a considerable amount of manual sewing and cutting by skilled personnel;
it requires the purchase and use of expensive equipment such as
sewing machines; and it requires excessive handling of individual
piece goods as they are cut and fabricated into a finished bra cup.
Perhaps even more importantly, however, the repeated cutting and
sewing required to fabricate bra cups from separate half pieces
greatly increases the opportunity for manufacturing error, by introduction
of the human variable of sewing, and often times results in poorly
fitting bra cups that must be altered through adjustment of straps
and accessories. In addition, the seams which appear across the
center portion of bra cups made by such currently used brassiere
manufacturing techniques are less comfortable for wearers, less
aesthetically pleasing because the seams tend to show through some
blouses and sweaters as ridges, and thus, far less useful for a
variety of fashion end uses than one-piece molded bra cups.
A one-piece molded bra cup, therefore, would not only eliminate
many of the comfort and aesthetic problems for wearers, but would
greatly reduce brassiere manufacturing costs by eliminating both
the need for additional manufacturing personnel to cut and sew separate
half-pieces of fabric together and the need for additional sewing
and cutting equipment to carry out the bra cup manufacture. As a
consequence of the many advantages which result from the use of
a one-piece molded bra cup (instead of the conventional two-piece
approach), considerable interest has developed in the manufacture
of laminate materials which are capable of being efficiently and
effectively molded into a one-piece bra cup. Although processes
have been attempted to manufacture laminate materials suitable for
one-piece molding, none has proved entirely successful. In part,
this has happened because of insufficient bonding between the laminate
layers and because of the inability of the resulting laminate materials
to meet the very stringent commercial requirements for bra cups,
such as permanence of form, washability, strength, durability, softness,
flexibility, smoothness of inner surfaces, and perhaps most importantly,
the absence of wrinkling, fabric slippage and decorative pattern
distortion.
SUMMARY OF THE INVENTION
The laminate materials of the present invention have overcome the
various above-described problems associated with prior art laminate
compositions, and, as a consequence, are particularly well suited
for use in making molded one-piece bra cups that can meet the stringent
commercial criteria for bra cups and brassieres.
The present invention involves unique multi-layered laminate sheets,
which have been demonstrated to be particularly suitable for use
in making molded one-piece bra cups for brassieres. Preferably,
the uniformly pre-shrunk, laminated sheet, and thus the completed
bra cup as well, has a three layer construction, the top and bottom
outer layers preferably being constructed from woven fabric or lace-like
materials made from polyester or related type fibers, while the
center or intermediate layer is preferably constructed from a non-woven
fiberfill type material of bonded polyester or related fibers. The
materials used for the outer and intermediate layers are desirably
compatible with one another and have identical or similar forming
and shrinking characteristics during molding or the application
of uniform heat and pressure.
The laminate sheets of the present invention are made by a process
in which an adhesive is applied to the center fiberfill layer in
two passes, a first pass in which one of the outer fabric layers
is bonded to one side of the fiberfill layer, and then dried and
partially shrunk through the application of heat and uniform pressure,
and a second pass in which the other outer fabric layer is bonded
in the same manner to the opposite side of the fiberfill layer and
similarly dried and partially shrunk. It should be understood, of
course, that the laminate sheets could also be made in a single
pass merely by applying suitable adhesive to both sides of the fiberfill
layer simultaneously.
Unlike prior art laminates, sufficient adhesive is applied to the
intermediate fiberfill layer to insure a strong secure bond between
it and the outer fabric layers. Preferably, adhesive is applied
to the fiberfill layer by a reverse roll which is rotated in a direction
opposite to the direction that the fiberfill layer itself is moving.
This reverse direction application of adhesive results in a deep
penetration of adhesive material into the fiberfill layer, insures
the formation of a desirably strong, secure bond between the outer
and fiberfill layers, and promotes uniform shrinkage of the outer
and intermediate fiberfill layers during subsequent molding operations,
all of which enhance the resultant properties of the finished laminate
sheet and make it highly desirable for use in making molded one-piece
bra cups.
After reverse application of adhesive, the coated side of the fiberfill
layer is brought into contact with one of the outer fabric layers,
and pressed against a rotating heated drum by a moving blanket which
applies a uniform and constant pressure to the two layers. This
continuous and uniform application of heat and pressure also serves
to enhance the properties of the resultant laminate sheet by increasing
the penetration of the adhesive into the fiberfill layer and by
insuring a controlled uniform shrinkage of the laminate material.
Thus, through proper selection of shrink compatible fabric and
fiberfill materials, the use of a reverse application and deep penetration
of adhesive, and the application of uniform and constant heat and
pressure after the application of adhesive, a controlled pre-shrinkage
of the resultant laminate sheet occurs before the sheet is heat
and pressure molded into finished one-piece bra cups. During subsequent
heat and pressure molding, therefore, the laminate materials of
this invention do not experience non-uniform shrinkage between layers,
do not warp or wrinkle, and do not have the many undesired properties
that make other laminate materials ill-suited for use in making
molded one-piece bra cups.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of one embodiment of a process for making
the laminate compositions of this invention, illustrating the manner
in which one of the outer fabric layers of the finished laminate
products is bonded to an intermediate fiberfill layer of material;
FIG. 2 is an enlarged end view of a pre-shrunk finished three-ply
laminate material, suitable for use in making one-piece molded bra
cups, having a non-woven fiberfill intermediate layer disposed between
and securely bonded to two separate fabric outer layers; and
FIG. 3 is an end view of one embodiment of the pre-shrunk three-ply
laminate material of this invention, which illustrates the high
degree of bonding which exists between the outer and intermediate
layers of material, as the outer layers are pulled apart.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, which illustrate one embodiment
of the process and resultant laminate products of this invention,
FIG. 1 shows the general arrangement and operative relation of various
component parts of a modified laminating apparatus useful in the
practice of this invention.
In the practice of the illustrated embodiment of the present invention,
a roll of non-woven fiberfill material 20 (the intermediate layer
in the resultant laminate sheet), after being properly stabilized
by roll 11 is passed from supply roll 10 around an adjustable roll
12 which adjusts and insures that a proper feeding angle exists
and that tension is applied to the fiberfill layer 20 as it is passed
into the adhesive application area, sufficient adhesive is applied
to the fiberfill layer 20 to insure a strong, secure bond between
it and the outer fabric layer 30. This is at least in part accomplished
through the action of reverse roll 15 which as indicated by the
arrows, is rotated in a clockwise direction opposite to the direction
of movement of fiberfill layer 20.
Unlike various prior art laminate structures, such as that described
in U.S. Pat. No. 3799174 adhesive material 31 is applied to the
intermediate fiberfill layer 20 in such a manner to insure substantial
penetration of adhesive into the fiberfill layer, e.g., to levels
between about 1/3 to 1/2 the overall thickness of the fiberfill
layer on each side of the fiberfill layer after final application
of heat and pressure to the laminate. A surface bonding agent which
is capable of only lightly bonding the fiberfill and outer fabric
layers is not sufficient to provide adequate bonding, and indeed
is undesirable. Moreover, as shown in FIG. 3 the outer layers 30
are more than just tacked to the fiberfill layer 20 since as the
outer layers 30 are pulled apart, substantial amounts of fiberfill
material are secured to the outer layers.
Adhesive material 31 contained in trough 32 is removed by a partially
immersed rotating transfer roll 15A, and is applied first to reverse
roll 15 and then in a continuous manner to the moving fiberfill
layer 20. The reverse action of roll 15 and fiberfill layer 20 results
in a deep penetration of adhesive into the continuously moving fiberfill
layer and greatly enhances the resultant properties of the finished
laminate sheet. Preferably, the speed of rotation of reverse roll
15 is regulated so that the appropriate quantity and degree of penetration
of adhesive material 31 can be appropriately adjusted for various
types of fiberfill material, as set forth in greater detail in the
Example given below.
After application of the adhesive, the coated fiberfill layer is
passed around a feeder roll 16 which adjusts the degree of tension
applied to the fiberfill layer 20. From feeder roll 16 the coated
and partially impregnated fiberfill layer moves across spreader
roll 17 which stretches and elongates the fiberfill to increase
its surface area immediately prior to its initial point of contact
40 with outer fabric layer 30.
The outer fabric layer 30 in turn is removed from supply roll 33
and passes across two bars 34 and 35 the latter of which is slightly
bowed so as to maintain a smooth and taut surface for the fabric
layer 30 immediately prior to its initial point of contact 40 with
the treated fiberfill layer 20.
The heating and curing area of the illustrated embodiment indicated
generally as 50 accomplishes two objectives in the laminating process;
it first serves to securely bond the outer fabric layer 30 to the
coated fiberfill layer 20 and secondly serves to uniformly and
partially pre-shrink the resultant laminate material. This heating
and curng area 50 is preferably made up of a heated rotating drum
41 and a superimposed endless blanket 42 which surrounds and engages
the major portion of drum 41. A series of rolls 43 are spaced about
and rotatably support endless blanket 42 as it rotates about the
outer circumference of drum 41. The rollers 43 maintain blanket
42 in spaced, circumferential relationship with drum 41 so that
blanket 42 can apply a uniform and constant pressure to the treated
fiberfill layer 20 and fabric layer 30 as they come into contact
around rotating drum 41 and insure the proper amount of final penetration
of adhesive into the fiberfill layer.
The uniform pressure is applied by a piston 45 which is attached
at one end to roll 44 and at its other end 46 to the frame 47 of
the laminating apparatus. During operation, piston 45 is securely
locked into position on frame 47 to maintain a constant and uniform
pressure on endless blanket 42 and thus, on the contacting outer
fabric layer 30 and intermediate fiberfill layer 20 as they pass
between blanket 42 and heated drum 41.
After the contacting outer fabric layer 30 and fiberfill layer
20 travel across the circumference (approximately 4/5ths the circumference)
of heated drum 41 they are passed beneath heater 48 which acts
to further dry, cure and shrink the laminated layers, and then are
collected on take-up roll 49. In order to complete the entire laminating
process and make a three-layered structure, the two laminated layers,
indicated as 53 are removed from take-up roll 49 placed on roll
10 and reprocessed in a second pass through the process so that
a second outer layer 30 can be similarly bonded to the other (non-bonded)
side of fiberfill layer 20.
Therefore, the resultant laminate sheet, shown generally in FIG.
2 comprises two outer fabric layers 30 which are securely bonded
to a non-woven, intermediate fiberfill layer 20. Preferably, outer
fabric layers 30 and intermediate fiberfill layer 20 are made from
compatible fiber materials which have similar or identical shrink
properties when subjected to heat and pressure. Although a variety
of materials can be used for the fabric layers 30 and fiberfill
layer 20 provided they are compatible, polyester fibers have been
found to be particularly suitable for use in the present invention.
In particular, woven polyester fibers, such as "Dacron"
polyester or "Qiana" polyester, as well as laces and woven
polyester-cotton mixtures having deniers in the range of 20 to 70
have been found to be particularly suitable for use as the outer
fabric layers. The intermediate fiberfill layer, on the other hand,
is desirably made of random, garnet (fibers oriented in one direction)
or isomisor (fibers oriented in -x and -y directions) non-woven
fibers, preferably polyester staple fibers of the conventional drawn
or oriented type employed in the textile industry, and having a
length in the range of one to two inches, or unplasticized polyester
staple fibers of the undrawn or amorphous type, also having a length
in the range of one to two inches. The adhesive materials found
particularly useful in the practice of this invention are aqueous
dispersions or emulsions of carboxylic acrylate polymers, including
cross-linked synthetic polyacrylic aqueous emulsions, having a shipped
viscosity of about 7500 cps, a density of about 8.8 pounds/gallon,
a pH of about 6.7 a total solids content of about 44.5 percent
by weight and a cure time of approximately three minutes at 290.degree.
F. It should be understood, of course, that adhesive materials and
outer fabric and intermediate, non-woven fiberfill materials other
than those discussed herein would be suitable for use in the practice
of the present invention, the polyester fibers and polyacrylate
adhesives merely being more desirable than other compositions.
It has been determined that the properties of the partially pre-shrunk
laminate products of this invention are particularly well suited
for making molded, one-piece bra cups. For example, the laminate
products of this invention are porous and breathable so as to permit
the passage of air and moisture; they do not abrade skin; and after
molding they have sufficient body, strength and resilience to hold
their shape, even after repeated washing. Perhaps even more significant,
the laminate products of this invention can be readily heat and
pressure molded without wrinkling or distorting, and because of
the controlled pre-shrink which occurs during processing, without
excessive, non-uniform shrinking between individual laminate layers.
Although it is generally preferred that adhesive be applied to
the fiberfill layer during processing, it is sometimes more desirable
for some fabrics to reverse the positions of the outer fabric and
fiberfill layers so that adhesive is applied to the outer fabric
layers instead of the fiberfill layer. The amount of adhesive applied
to either the fiberfill or outer layers is adjusted by means of
the speed of reverse roll 15. Typically, sufficient adhesive is
applied to create a strong, secure bond between the outer fabric
and intermediate fiberfill layers. As shown in FIG. 3 sufficient
adhesive is considered applied when about 1/3 to 1/2 the overall
thickness of the fiberfill layer on each side of the fiberfill layer
is penetrated by adhesive, and the outer layers of the finished
laminate cannot be torn apart without a considerable amount of the
fiberfill layer remaining attached to each of the outer fabric layers.
Such a strong, secure bond between the outer fabric layers and intermediate
fiberfill layer prevents a total shift between the outer layers
during molding, which has been found to have an undesirable effect
on the resultant properties of the molded bra cup.
During the application of heat and uniform pressure to the contacting
fabric and fiberfill layers as they pass around rotating drum 41
temperatures in the range of about 175.degree. F. to 330.degree.
F. have been found to be suitable to adequately cure and pre-shrink
the fabric materials useful in the practice of this invention. Temperatures
in the range of about 230.degree. F. to 240.degree. F., for example,
are particularly suitable for the polyester fibers and polyacrylic
adhesives used in the practice of the present invention. The exact
temperature ranges selected for any given combination of outer fabric
and intermediate fiberfill layers is typically below that point
at which the fiber memory is broken, although it is possible that
for some fibers, temperatures above that required to break the fiber
memory can be used.
Sufficient pressure is applied by the endless blanket 42 to insure
the formation of a firm bond between the fabric and fiberfill layers,
as well as adequate penetration of adhesive into the fiberfill layer,
and is best determined for any given fabric combination through
empirical techniques, i.e., pressures sufficient to maintain the
fabric and fiberfill layers in firm contact so that after curing
the outer fabric layers cannot be torn apart without removing significant
portions of attached fiberfill as shown in FIG. 3.
Although there are many advantages to the present invention, the
most meaningful advantage is that it can be used to continuously
make laminate sheets that are especially suited for molding one-piece
bra cups. It is believed that these advantageous properties are
imparted to the finished laminate sheets because of the action of
the variable speed reverse roll which drives adhesive into the fiberfill
layer, thus insuring a strong bond, and because of the constant
and uniform application of heat and pressure to the laminate layers
as adhesive further penetrates the fiberfill layer and is being
cured. In this way, the finished three-layered laminate is partially
pre-shrunk in a uniform fashion, and is thus not susceptible to
the many problems associated with rapid, non-uniform shrinking during
subsequent molding operations.
EXAMPLE
Four separate rolls of laminate sheets were made in the manner
and with the apparatus described in greater detail above, in which
the speed of rotation of reverse roll 15 was varied to vary the
amount and the degree of penetration of adhesive applied to the
intermediate fiberfill layer 20. In each case, one outer fabric
layer material was 40 denier polyester and the other outer layer
20 denier polyester, while the intermediate fiberfill layer was
polyester staple fibers, random web, 2.9 ounces per yard. The same
adhesive was used to make each sample, and each sample roll of laminate
was numbered from 1 to 4.
______________________________________ Sample No. Amount of Adhesive
______________________________________ 1 50 percent less than control
2 25 percent less than control 3 Control 4 25 percent more than
control ______________________________________
The amount of adhesive used in control sample 3 was determined
by adjusting the speed of reverse roll 15 to insure penetration
of adhesive after application of heat and pressure to approximately
1/2 the overall thickness of intermediate layer 20. The speed of
reverse roll 15 was thereafter adjusted to insure approximately
50 percent less adhesive (50 percent decrease in roll speed) in
sample 1 25 percent less in sample 2 and 25 percent more in sample
4.
Sample 1 can best be described as having only light bonding between
the outer fabric and intermediate fiberfill layers to the point
that the layers are almost tacked together as described in U.S.
Pat. No. 3799174 even after application of heat and pressure.
Sample 2 has penetration of adhesive to approximately 1/4th the
overall thickness of the intermediate layer on each pass, while
sample 4 has penetration to approximately 3/4th the thickness of
the intermediate layer on each pass after application of heat and
pressure. Four separate two yerd sample rolls of 3 ply laminate
were made as set forth above and then molded into bra cups as set
forth below on conventional molding equipment.
Trial molding runs were made to establish the correct temperature,
pressure and time for the application of the molds to roll 3 (control)
material. It was established that the proper molding conditions
to obtain a consistently a-propriate molded product from roll 3
were 330.degree. F. at 120 pounds per square inch for 25 seconds.
These conditions were left unchanged during the entire testing period.
Three samples from roll 3 were obtained, one at the beginning of
the testing period, one during the period, and one at the close
of the period. Each were inspected and deemed merchantable and therefore
acceptable.
The other samples were rated as either acceptable (being of the
same quality and merchantability as the samples numbered 3), unacceptable
or marginal. Unacceptable means that a wrinkling occurred on the
inner and outer layers creating a lack of uniformity in thickness
in the cup. As such, the cup was insufficiently aesthetic and ran
the risk of developing larger air pockets when a consumer applied
normal washing techniques. This wrinkling or buckling was apparently
the result of uneven adhesive distribution leaving areas unbonded.
The term "marginal" was used in most cases where it would
have been possible to utilize the product, however, greater experimentation
would have been preferred to attain sample 3 quality.
Of three sample 1 products, none was found acceptable with one
acceptable and two marginal.
Of four sample 2 products, one was found to be acceptable and three
unacceptable.
Of three sample 3 products, all were found to be acceptable.
Of three sample 4 products, none was found acceptable with one
unacceptable and two marginal.
It should be understood, of course, that the preferred laminate
compositions of the present invention have adhesive penetration
levels, after application of heat and pressure, that are between
about 1/3 and 1/2 the overall thickness of the fiberfill layer,
e.g., 1/3 to 1/2 the overall thickness on each side of the fiberfill
layer. This is accomplished in two stages, the first being the application
of adequate adhesive by reverse roll 15 to insure adhesive penetration
in the fiberfill layer to levels at least between 1/20th and 1/10th
the overall thcikness of the fiberfill layer, and the second being
the application of heat and uniform pressure (with blanket 42 for
example) to obtain the final desired adhesive penetration levels
of 1/3 to 1/2 the overall thickness of the fiberfill layer. Naturally,
when insufficient amounts of adhesive are initially applied by reverse
roll 15 then the subsequent adhesive penetration levels normally
accomplished through the application of heat and uniform pressure
cannot be achieved.
Although only three-layered laminates have been discussed and tested
herein, it should be understood that multi-layered laminated products
can be made from other materials than disclosed herein without departing
from the spirit and scope of the present invention.
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