Note: Descriptions are shown in the official language in which they were submitted.
10939:12
The method of this invention is particularly suitable
for forming flexible or rigid foam laminates, including foam
backed carpet laminates. Rigid foam laminates may be used in
autornotive applications for example for contoured wheel covers,
interior panelling and the like.
Foam-fabric laminates are presently formed by adhesive
bonding a foam sheet to the fabric or casting a foam sheet upon
a carrier and applying the fabric, under pressure, after
foaming and prior to complete curing. Generally, an adhesive
is still required. Where the foam is applied in a fluid form
to a porous fabric or substrate, such as carpeting, the foam
bleeds through the fabric during blowing. The need therefore
remains for a method of applying fluid foam directly to a
porous substrate, eliminating the requirement for casting the
foam prior to application to the substrate and bonding.
Another problem in the prior art has been to form a
contoured rigid foam-fabric laminate without wrinkling the
fabric. Where the foam sheet is cast prior to application of
the fabric, wrinkles are f~rmed in the fabric. One technique
^ 20 to reduce wrinkles has been to utilize stretcher frames, which
would require stretching of the fabric prior to application of
the foam layer. Finally, it has been found difficult to cut
or trim the foam-fabric laminate-~ of the prior art because of
the flexibility of the fabric relative to the foam. These
and other problems of the prior art have been solved by the
method and foam laminate of the present invention.
One aspect of the method of forming a foam laminate
of this invention concerns heating a substrate to eliminate the
necessity of precasting a foam layer and the necessity of an
3~ adhesive bond between the foam and substrate, reducing the
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time, labor and apparatus for such operations. Additionally,
this same method aspect forms a permanent, integral bond between
the foam layer and substrate, reducing the chances of delamina-
tion A further aspect of this invention includes forming
a laminate of substrate and foam in a mold (a) to complete
the foaming of the foam layer (b) to cure the foam and (c)
to shape the laminate. A third aspect concerns the formation
of a foam laminate with a skrim embedded within the foam layer.
Each of these aspects may be practiced in combination or
separately. For example, the first aspect is specifically and
preferably for use with a porous substrate, and may or may not
be used in combination with a skrim or a molding step. Further,
the molding aspect does not require the heating step involved
with the first aspect of the invention, nor the use of a skrim.
Thus, the method of this invention may be utilized
with substantially any substrate, including relatively porous
fabrics such as carpeting. Further, relatively rigid foams
and substrates may be formed into permanently contoured shapes,
without pre-forming either the foam or substrate layers. As
described, the method of this invention also substantially
eliminates the problem of wrinkling of the substrate, during
forming. Finally, the preferred method of this invention
results in a unique foam laminate, which ma~ be easily formed
and trimmed without special equipment.
The first aspect of the method of this invention in-
cludes the steps of heating the surface of the substrate, such
as a porous fabric, to which the foam is to be applied, applying
a layer of foaming plastic to the heated substrate surface
and completing the foaming of the plastic layer and curing the
foam and substrate into an integral homogeneous foam-substrate
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laminate. In the preferred method of this inven-tion, a first
layer of foaming plastic is applied to the heated substrate sur-
face, providing a blow barrier at the foam-substrate interface.
A second layer of foamable plastic may then be applied immed-
iately over the first foam layer, permitting the building of
the foam layer into a layer of substantial thickness. As des-
cribed, the substrate may be a relatively porous fabric. For
example, the foam may be applied directly to the backing of a
carpet, providing an integral foam backing for the carpet. The
substrate is preferably heated to at least lOODF., but below
the charring temperature of the substrate. The preferred foam
in the method and laminate of this invention is a polyurethane
foam, which may be a relatively rigid polyurethane foam, as
described below.
Where the method of this invention is used to form a
permanent contoured laminate, the plastic is preferably a rela-
tively-rigid polyurethane. The method of this aspect of the
invention then includes forming the laminate, preferably under
heat and pressure, in a contoured shape, preferably in a matched
set die, or the like. The laminate is received in the die
immediately after applying foam to a substrate, prior to complete
foaming, wherein the foam is utiliæed as a forming media. The
- -Y foaming plastic in the die aids in the forming of the contoured
configuration of the laminate. Three method steps are then
included in the forming die, including completion of the
~; foaming, curing of the foam and shaping of the foam laminate.
The resultant formed laminate is~surprisingly free of folds
and creases, which is believed to be caused by the compressive
strength and pressure of the foam, wherein the strength of the
; 30 foam and pressure offset~ the tendency of the flexible substrate
to wrinkle. As stated previously, this aspect of the invention
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may he practiced separately from heating the substrate to pre-
vent foam bleedthrough, such as with an impervious substrate.
The substrate may also require trimming which has been
a problem withthe prior art primarily because of the difference
in physical properties between the substrate and the foam layer.
For example, when the foam is applied to a carpet, the carpet
will tear during trimming and the foam will crack. This
problem has also been solved by the improved foam laminate of
this invention.
The preferred embodiment of the foam laminate includes
the substrate, such as a napped carpet, a polyurethane foam
layer permanently affixed to the substrate and a grid-like
porous non-resilient skrim located within $he polyurethane foam
continuous through the skrim and the skrim located bewteen the
substrate-polyurethane foam interface and the outer skin of
the foam layer. The skrim is preferably flexible and non-
resilient and permits the laminate to be easily trimmed without
tParing of the substrate.
In the method of this aspect of the invention, the
skrim is disposed over the face of the substrate which is to
receive the foam layer and the substrate may be heated through
the skrim, as by radiant heating. The foam layer is then
sprayed or otherwise applied through the skrim, causing the
skrim to ~Ifloat~ in the foam layer. Where two layers of foam
are applied to the substrate, for example, the skrim will float
at least one-third of the distance between the substrate and
the exposed skin of the foam, preferably near the skin of the
foam. The size of the skrim grid openings should therefore be
selected to cause the skrim to float, as desired. Again, this
aspect of the invention may be practiced with or without the
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steps of either heating the substrate or molding the laminate
in a die.
Other advantages and meritorious features of the
disclosed foam laminate and method of this invention will be
more fully understood from the following description of the
preferred embodiments and methods of this invention the appended
claims and the drawings, a brief description of which follows.
Figure 1 illustrates a process line suitable for
carrying out the separate aspects in the process of this inven- ;
tion;
Figure 2 is a top perspective view of a skrim which
may be utilized in the process and foam laminate of this inven-
tion;
Figure 3 is a top perspective view of the foam laminate
of this invention formed by the method disclosed in Figure l;
and
Figure 4 is a side cross-sectional view of the laminate
shown in Figure 3, in the direction of view arrows 4-4.
The process line 20 shown in Figure 1 includes a
heater station 22, a foam application station 24 and a forming
station 26. The process illustrated in Figure 1 applies a
foam backing to a carpet section and forms the carpet section
into a contoured shape, such as a self-supporting automotive
interior wheel cover used in a stationwagon, fastback or the
like. It will be understood however that the process of this
invention may be utilized to form various types of laminates,
as will be described more fully below.
In the process line shown in Figure 1, carpeting 28
is continuously fed from a roller 30 and skrim 34 is fed from
30 roller 36, over the carpeting, to heater 40 of heater station 22.
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The heater may be a conventional radiant heater having a
plurality of radiant heaters 42, heating the carpet backing
prior to application of the foam. The heaters will also dry
the carpet, removing entrained moisture which may be detrimental
to the foam or laminate. The carpeting may be of any conven-
tional design, including a napped side and a relatively smooth
backing, either porous or non-porous.
Heating of the substrate, which in this case is a
relatively porous carpet, eliminates the problem of the foam
"bleeding" through the carpet upon application of the foam. When
the foam contacts the heated carpet backing, it begins to foam
immediately, forming a blow barrier and preventing the foam
from bleeding through or penetrating the carpet. As described
above, this has been a particularly difficult problem in the
application of a foam layer directly upon a porous substrate,
such as a carpet. When the carpet is heated, the foam expands
upwardly or away from the carpet, providing a bridge without
substantial penetration. Further, a mechanical interlock is
provided between the porous substrate and the f~am layer, pro-
viding excellent adhesion. Where the substrate is a carpet, thefoam forms a tuft lock, actually improving the tuft retention
of the carpet.
The preferred temperature to which the substrate is
heated will depend upon the heat stability of the substrate and
the particular foam utilized. In most applications, the tempera-
ture of the substrate should be at least 100F. and should pre-
ferably be greater than 120F. In the application of a poly-
urethane foam to a conventional carpet backing, the preferred
temperature range is between about 120 and 150F. The heated
carpet and skrim is then received in the foam application station
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24.
In the disclosed embodiment of the process line 20,
foam is applied to the heated carpet backing by a reciprocating
nozzle assembly 46. The nozæle assembly includes a drum 48
having an inlet pipe 50 receiving the constituents of the
foamable plastic. In a conventional spnay nozzle assembly,
the constituents of the foam are mixed at the spray nozzle.
The nozzles are reciprocated by a conventional linkage, includ-
ing a power link 52 driveably connected to a drive shaft 54
and pivotally connected to a follower link 56. The follower
56 is pivotally connected to nozzle tube 58, which is pivotally
connected to the drum at 60. Drive link 52 is thus rotated
about drive shaft 54, pivotally reciprocating nozzle tube 58
from the position shown to the position shown in phantom at 59.
The constituents of the foamable plastic are received through
tube 50, mixed in!drum 48 or previously mixed and sprayed on
the heated carpet backing through nozzles 62. It will be
understood that any suitable method may be used to apply the
foam to the heated carpet backing, including casting with a
metering knife, or the like. The preferred method however
includes spraying the foamable plastic laterally or axially
on the carpet because the thickness of the foam may be built-up
by two or more passes of the disclosed reciprocating nozzle.
Where the foam is applied to a heated porous substrate
by spraying through a reciprocating nozzle, the porous substrate
is first impregnated with foam, forming a blow barrier and mech-
anical interlock as described above. In the second pass of the
reciprocating nozzle, the foam is applied over the impregnated
backing, building-up an integral, homogeneous foam layer. The
thickness of the first layer of foam applied to the substrate
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wlll primarily depend upon the porosity and temperature of the
substrate, but will also depend upon the type of foam used.
Where the foam is applied to a conventional carpet and is
heated to between about 120 and 150F., as describedabove~ the
foam may be applied in thicknesses of about one-quarter inch
foamed thickness per pas~ of the reciprocating nozzle, forming
foam layer 66 shown in Figure 1.
The foam used in the method of this invention will
depend upon the particular application of the composite
laminate. A flexible polyurethane foam may be preferred for
conventional carpet backing. A relatively rigid polyurethane
foam having a density of about two pounds per cubic foot has
been found suitable for the automotive applications described
above. One example of a suitable rigid polyurethane foam in-
cludes an isocyanate component comprising 90% polymeric iso-
cyanate and 5 to 10% inert flame retarder and a resin or
polyol component comprising 60 to 7~% polyether polyol, 20 to
30% fluorocarbon ll-B (trichlorofluoromethane) and approximatel~
1% silicone surfactant and metal or acid salt catalysts. This
foam composition may be purchased from Urechem Corporation.
Other suitable rigid and flexible polyurethane foam compositions
are disclosed in British Patent No. 1,306,372 of the Union
Carbide Corporation.
The composite laminate may then be cured by conventional
means. Where a rigid polyurethane foam is utilizéd and the
laminate is to bç permanently ~ormed into a contoured shape, the
invention contemplates immediately inserting the laminate into
a die, such as shown at forming station 26, prior to complete
foaming and curing of the foam. A cutting blade 68 is shown in
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Figure 1, which cuts the laminate into sections suitable for
receipt in the die. It is understood however that the carpet
and skrim may be pre-cut into suitable sections, prior to
receipt in the heating station 22 or the entire process may be
continuous. It is also to be understood that the aspect of the
invention concerned with forming the contoured shape in the die
at station 26 does not necessarily require the heating step at
station 22, for example, such as when an impervious substrate is
used.
The die assembly shown in forming station 26 is a
conventional matched set die assembly, including a lower platen
or die 74 having conventional heat transfer coils 76 located
within the die platen adjacent the interface between the lower
platen 74 and the upper platen 78. The upper platen 78 is
supported in the disclosed embodiment by frame 80 having con~
~rentional hydraulic rams 82 including pistons 84. Pressure is
applied to the upper platen by extending piston rods 84 and the
die is opened by retracting piston rods 84, as shown in phantom
at 79.
.
As described above, the ~oam-carpet laminate is placed
in the die as soon as the final foam layer is applied. The die
opens immediately upon completion of the last pass of the
reciprocating nozzle, the laminate is inserted and the die is
closed.
Three steps are carried out in the forming die, in-
cluding (1) completion of-foaming, (2) curing of the foam and
(3) shaping of the foam laminate. This method of the invention
thus utilizes the foam as a forming media. Where the foaming
is completed in the die, substantial pressures result and the
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pressure aids in the forming of the contoured configuration
of the laminate. As described above, this is believed to be
caused by the compression strength and pressure of the foam.
The resultant contoured foam laminate is substantially free of
folds and creases.
A suitable die for the method of this invention, as
described, applied a to 10 pounds per square inch pressure.
In the disclosed embodiment, the die is also heated by passing
steam or other fluid medium through the heat transfer coil 76.
The die may be heated to a temperature of about 150F. using
conventional steam, It is understood that the method of forming
of this invention may also be utilized to form foam laminates
having relatively rigid impervious substrates. For example,
contoured shapes may be formed using substrates such as coated
asphalt impregnated craft or chip board, cardboard and the like.
The foam will form a permanent bond to such materials in the
method of this invention.
The method of this invention may also include a final
trimming step, not shown, using a conventional trimmer blade,
such as shown at 68 in Figure 1. The foam laminate of this
invention is particularly adapted to permit easy trimming,
which is a problem in a foam laminate having a relatively
resilient substrate, such as carpet. The utilization of a
non-resilient skrim, retained in position within the foam layer,
permits cutting of the laminate without tearing of the carpet.
Further, a relatively r~gid foam, such as a rigid polyurethane
foam, will break easily when apart from the composite laminate
of this invention, particularly under compressive stress. The
utilization of a non~resilient skrim has solved this problem.
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A suitable skrim for the foam laminate of this inven-
tion is shown at 34 in Figure 2~ The preferred skrim is formed
of non-resilient polyester strands, such as the interwoven per-
pendicular strands 94 and 96 shown in Figure 2. Skrim of this
type are available commercially from various sources. In the
method of this invention the skrim is received on top of the
carpet backing as shown in Figure 1 and the carpet backing is
heated through the skrim. Finally, the foamable plastic is
sprayed through the skrim in the foam application station 24,
causing the skrim to "float" upwardly or away from the carpet
backing as the foam expands. The size of the skrim grid open-
ings should therefore be selected to cause the skrim to float,
as desired. A skrim having perpendicular strands defining
apertures of one-eighth to one-quarter inch, measured from
cross-over points, has been found suitable for the foam laminate
of this invention. In this embodiment, the skrim floats until
it is located at least one-third of the distance between the
carpet backing 100 and the skin 98 of the foam as shown in
Figure 4.
The foam laminate shown in Figures 3 and 4 has been
formed by the method of this invention. The laminate 90 includes
a contoured portion 96 formed in the forming station 26 of Figure
1. As described above, the carpet portion 28 is formed free of
folds, creases or the like and the foam portion 66 is permanent-
ly affixed to the back or reverse side of the carpet 100 and is
homogeneous, although applied in plural passes of the recipro-
cating nozzle assembly 46. The contoured foam laminate is formed
o~ a relatively rigid polyuxethane, such as described above and
will retain the contoured shape after repeated flexing. The foam
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alone is difficult to cut because it is subject to cracking
or breakiny and the carpet alone is more easily torn than cut.
The foam laminate 90 however may be easily trimmed, primarily
because of the non-resilient skrim,
Again, it will be understood that the improvements of
the method of this invention may be used individually or in
combination to produce foam laminates other than the foam lamin-
ate shown in Figures 3 and 4. For example, a flexible foam may
be applied to a carpet backing or other relatively porous fabric
materials. Alternatively, an impervious substrate may be used
in combination with a relatively rigid foam which is then formed
into a pérmanently contoured shape as described above, this
process not requiring the heating step since foam bleedthrough
is not a problem, The skrim may not be required in certain
applications, particularly where~strength is not a factor or
a non-resilient substrate is used.
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