U.S. patent application number 10/099659 was filed with the patent office on 2003-09-18 for insulating material.
Invention is credited to Tilton, Jeffrey A..
Application Number | 20030176131 10/099659 |
Document ID | / |
Family ID | 28039650 |
Filed Date | 2003-09-18 |
United States Patent
Application |
20030176131 |
Kind Code |
A1 |
Tilton, Jeffrey A. |
September 18, 2003 |
Insulating material
Abstract
An insulating material is constructed in weight percent from
about 20-60% low melt bicomponent fiber, 10-40% high melt
bicomponent fiber and 20-60% staple fiber. The material provides a
unique combination of strength, acoustical insulating and even
thermal insulating properties heretofore unavailable in the
art.
Inventors: |
Tilton, Jeffrey A.;
(Louisville, KY) |
Correspondence
Address: |
OWENS CORNING
2790 COLUMBUS ROAD
GRANVILLE
OH
43023
US
|
Family ID: |
28039650 |
Appl. No.: |
10/099659 |
Filed: |
March 15, 2002 |
Current U.S.
Class: |
442/361 ;
442/357; 442/362; 442/364 |
Current CPC
Class: |
G10K 11/162 20130101;
Y10T 442/633 20150401; Y10T 442/641 20150401; B60R 13/08 20130101;
E04B 2001/7687 20130101; D04H 5/06 20130101; Y10T 442/637 20150401;
Y10T 442/638 20150401 |
Class at
Publication: |
442/361 ;
442/362; 442/364; 442/357 |
International
Class: |
D04H 005/00; D04H
001/10 |
Claims
What is claimed
1. An insulating material, comprising in weight percent about
20-60% low melt bicomponent fiber, 10-40% high melt bicomponent
fiber and 20-60% staple fiber.
2. The material of claim 1, including an average fiber diameter of
between about 10-30 microns.
3. The material of claim 1, including an average fiber diameter of
between about 16-24 microns.
4. The material of claim 1, including an average fiber diameter of
between about 18-22 microns.
5. The material of claim 1, wherein said material has a density of
between about 1.0-10.0 pcf and a flexural strength of between about
40-1200 psi.
6. The material of claim 5, wherein said material has the
acoustical absorption coefficients as follows:
1 freq (Hz) @ 2 pcf density 500 0.17-0.24 1000 0.29-0.63 2000
0.50-0.94 4000 0.71-0.99
7. The material of claim 6, wherein said material has a thermal
conductivity value of between about 0.20 and 0.30 at 2 pcf
density.
8. The material of claim 1, wherein said low melt and high melt
bicomponent fibers are a concentric sheath/core CoPET/PET.
9. The material of claim 8, wherein said staple fibers are selected
from a group of materials consisting of polyester fibers,
polyethylene fibers, polypropylene fibers, nylon fibers, rayon
fibers, glass fibers, natural fibers and mixtures thereof.
10. The material of claim 1, wherein said material has the
acoustical absorption coefficients as follows:
2 freq (Hz) @ 2 pcf density 500 0.17-0.24 1000 0.29-0.63 2000
0.50-0.94 4000 0.71-0.99
11. The material of claim 10, wherein said material has a thermal
conductivity value of between about 0.20 and 0.30 at 2 pcf
density.
12. The material of claim 11, wherein said staple fibers are
selected from a group of materials consisting of polyester fibers,
polyethylene fibers, polypropylene fibers, nylon fibers, rayon
fibers, glass fibers, natural fibers and mixtures thereof.
13. The material of claim 1, wherein said staple fibers are
selected from a group of materials consisting of polyester fibers,
polyethylene fibers, polypropylene fibers, nylon fibers, rayon
fibers, glass fibers, natural fibers and mixtures thereof.
14. The material of claim 13, wherein said low melt bicomponent
fibers are selected from a group of materials consisting of
copolyester/polyethylene terephthalate, poly 1,4
cyclohexanedimethyl terephthalate/polyethylene terephthalate, poly
1,4 cyclohexanedimethyl terephthalate/polypropylene,
glycol-modified polyethylene terephthalate/polyethylene
terephthalate, propylene/polyethylene terephthalate, nylon 6/nylon
66, polyethylene/glass, polymer/natural fibers and mixtures thereof
that yield differential melt flow temperatures.
15. The material of claim 14, wherein said bicomponent fibers are
in a configuration selected from a group consisting of sheath-core,
side-by-side, segmented pie and mixtures thereof.
16. The material of claim 14, wherein said low melt bicomponent
fibers have a melt flow temperature of about 100 to about
130.degree. C.
17. The material of claim 13, wherein said high melt bicomponent
fibers are selected from a group of materials consisting of
copolyester/polyethylene terephthalate, poly 1,4
cyclohexanedimethyl terephthalate/polyethylene terephthalate, poly
1,4 cyclohexanedimethyl terephthalate/polypropylene,
glycol-modified polyethylene terephthalate/polyethylene
terephthalate, propylene/polyethylene terephthalate, nylon 6/nylon
66, and mixtures thereof that yield differential melt flow
temperatures.
18. The material of claim 17, wherein said high melt bicomponent
fibers are in a configuration selected from a group consisting of
sheath-core, side-by-side, splitable segmented pie and mixtures
thereof.
19. The material of claim 17, wherein said high melt bicomponent
fibers have a melt flow temperature of about 170 to about
200.degree. C.
20. The material of claim 17, wherein crystalline/semicrystalline
bicomponent fibers having a melt flow temperature of about 150 to
about 180.degree. C. are substituted in part or whole for said high
melt bicomponent fiber.
Description
TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION
[0001] The present invention relates generally to the field of
acoustical and thermal insulation and, more particularly, to a
unique new insulating material of low-melt and high-melt
bicomponent fibers exhibiting a unique blend of structural and
acoustical insulating properties.
BACKGROUND OF THE INVENTION
[0002] Acoustical and thermal liners for application to vehicles
are well known in the art. These liners typically rely upon both
sound absorption, i.e. the ability to absorb incident sound waves
and transmission loss, i.e. the ability to reflect incident sound
waves, in order to provide sound attenuation. They also rely upon
thermal shielding properties to prevent or reduce the transmission
of heat from various heat sources (e.g. engine, transmission and
exhaust system), to the passenger compartment of the vehicle. Such
insulation is commonly employed as a hoodliner, dash liner and
firewall liner. More recently, such liners have been employed on
engine covers so as to attenuate the sound of the engine closer to
its source.
[0003] Examples of acoustical and thermal insulation in the form of
liners are disclosed in a number of prior art patents including
U.S. Pat. Nos. 4,851,283 to Holtrop et al. and 6,008,149 to
Copperwheat. As should be apparent from a review of these two
patents, engineers have generally found it necessary to construct
such liners from a laminate incorporating (a) one or more layers to
provide the desired acoustical and thermal insulating properties
and (b) one or more additional layers to provide the desire
mechanical strength properties which allow simple and convenient
installation as well as proper functional performance over a long
service life.
[0004] While a number of adhesives, adhesive webs and binding
fibers have been specifically developed over the years to secure
the various layers of the laminates together, laminated liners and
insulators have an inherent risk of delamination and failure. The
potential is, in fact, significant mainly due to the harsh
operating environment to which such liners and insulators are
subjected. Many liners and insulators are located near and/or are
designed to shield high heat sources such as the engine,
transmission and components of the exhaust system. As a result, the
liners and insulators are often subjected to temperatures in excess
of 200.degree. F. which have a tendency to degrade the adhesives or
binders over time.
[0005] Additionally, many liners and insulators are subjected to
water from the surface of the roadways which has a tendency to be
drawn by capillary action into the interface between the layers of
the liner or insulator. Such water may have a deleterious affect
upon the integrity of the adhesive layer over time. This is
particularly true when that water includes in solution salt or
other chemicals from the roadway which are corrosive and
destructive.
[0006] A need is therefore identified for a hood, dash, firewall or
engine cover liner incorporating a nonlaminate acoustical and
thermal insulating layer of polymer fibers which avoids any
inherent potential for delamination. Such a liner is suitable for
use in the high temperature operating environment of the engine
compartment and capable of providing the desired mechanical
strength and rigidity for ease of installation as well as the
desired acoustical and thermal insulating properties.
SUMMARY OF THE INVENTION
[0007] Accordingly, the present invention relates to an insulating
material exhibiting a unique combination of acoustical insulating
and strength/structural properties. The insulating material
comprises in weight percent from about 20-60% low melt bicomponent
fiber, 10-40% high melt bicomponent fiber and 20-60% staple fiber.
The melt includes an average fiber diameter of between about 10-30
microns, more typically 16-24 microns and most typically 18-22
microns. The material has a density of between about 1.0-10.0 pcf
and a flexural strength of between about 40-1200 psi. Still more
specifically describing the invention, the insulating material has
the acoustical absorption coefficients as follows: 0.17-0.24 at a
frequency of 500 Hz, 0.29-0.63 at a frequency of 1000 Hz, 0.50-0.94
at a frequency of 2000 Hz and 0.71-0.99 at a frequency of 4000 Hz
all at 2 pcf density.
[0008] Still further describing the invention, the insulating
material has a thermal conductivity value of between about 0.20 and
0.30 at 2 pcf density. The staple or bulking fibers are selected
from a group of materials consisting of polyester fibers,
polyethylene fibers, polypropylene fibers, nylon fibers, rayon
fibers, glass fibers, natural fibers and mixtures thereof.
[0009] The low melt bicomponent fibers are selected from a group of
materials consisting of copolyester/polyethylene terephthalate
(CoPET/PET), poly 1,4 cyclohexanedimethyl
terephthalate/polyethylene terephthalate (PCT/PET), poly 1,4
cyclohexanedimethyl terephthalate/polypropylene (PCT/PP),
glycol-modified polyethylene terephthalate/polyethylene
terephthalate (PETG/PET), propylene/polyethylene terephthalate
(PP/PET), nylon 6/nylon 66, polyethylene/glass, or other
combinations of polymers including polymer/glass and
polymer/natural fiber that yield differential melt flow
temperatures. The bicomponent fibers may be any of a variety of
configurations that yield acceptable fiber binding such as
sheath-core, side-by-side, segmented pie, etc. The low melt
bicomponent fibers are described as having a melt flow temperature
of about 100 to 130.degree. C.
[0010] The high melt bicomponent fibers are selected from a group
of materials consisting of copolyester/polyethylene terephthalate
(CoPET/PET), poly 1,4 cyclohexanedimethyl
terephthalate/polyethylene terephthalate (PCT/PET), poly 1,4
cyclohexanedimethyl terephthalate/polypropylene (PCT/PP),
glycol-modified polyethylene terephthalate/polyethylene
terephthalate (PETG/PET), propylene/polyethylene terephthalate
(PP/PET), nylon 6/nylon 66, or other combinations of polymers that
yield differential melt flow temperatures. The bicomponent fibers
may be any of a variety of configurations that yield acceptable
fiber binding such as sheath-core, side-by-side, splitable
segmented pie, etc. The high melt bicomponent is described as
having a melt flow temperature of about 170-200.degree. C.
Bicomponent fibers described as crystalline or semi-crystalline
which have a melt flow temperature of generally about 150 to
180.degree. C. may be substituted in part or whole for the high
melt bicomponent fiber.
BRIEF DESCRIPTION OF THE DRAWING
[0011] The accompanying drawing incorporated in and forming a part
of the specification, illustrates several aspects of the present
invention, and together with the description serves to explain the
principles of the invention. In the drawing:
[0012] FIG. 1 is a schematical side elevational view of one
possible embodiment of the present invention;
[0013] FIGS. 2-4 are schematical side elevational illustrations of
other possible alternative embodiments of the present
invention;
[0014] FIG. 5 is a graphical illustration comparing the flexural
strength in the machine direction of the structural/acoustical
insulating material of the present invention with a standard state
of the art polymer formulation; and
[0015] FIG. 6 is a graphical illustration comparing the flexural
strength in the cross machine direction of the
structural/acoustical insulating material of the present invention
with a standard state of the art polymer formulation.
[0016] Reference will now be made in detail to the present
preferred embodiment of the invention, an example of which is
illustrated in the accompanying drawing.
DETAILED DESCRIPTION OF THE INVENTION
[0017] The present invention relates to an insulating material that
is particularly noteworthy for its combination of structural and
acoustical properties. Specifically, as described below the
insulating material yields at least a 100% improvement in elastic
modulus over a standard polymer formulation while (1) maintaining
equivalent acoustics to the standard formulation, (2) yielding high
temperature performance and (3) having a minimal cost upcharge over
standard formulations. While in the past it has generally been
found necessary to give up a significant level of acoustical
performance or utilize much higher priced fibers or both to gain
improvement in structural properties, the present invention
achieves the dramatic increase in elastic modulus without
compromising acoustical properties or low production costs and as
such represents a significant advance in the art.
[0018] The insulating material of the present invention comprises
in weight percent from about 20-60% low melt bicomponent fiber,
10-40% high melt bicomponent fiber and 20-60% staple fiber. The
melt includes an average fiber diameter of between about 10-30
microns, or typically 16-24 microns and most typically 18-22
microns. The material has a density of between about 1.0-10.0 pcf
and a flexural strength of between about 40-1200 psi.
[0019] For purposes of clarity, the bicomponent fibers are
comprised of a principal polymer component and a binder polymer
component. The bicomponent fibers may be formed as sheath-core
fibers with the principal polymer component forming the core
material and the binder polymer component forming the sheath around
the core. It should be understood, however, that other arrangements
may be utilized such as a side-by-side arrangement. In any such
arrangement, the binder polymer component binds the bicomponent
fibers and the staple fibers to themselves and to each other.
[0020] The binder polymer component of the bicomponent fibers has a
softening point lower than the softening point of the principal
polymer component so that the two materials respond differently
upon heating. When heated to a temperature above the softening
point of the binder polymer component but below the softening
temperature of the principal polymer component, the binder
component softens and becomes sticky, thereby bonding the various
bicomponent fibers where they are in contact with each other and
the staple fibers. As long as the temperature is not raised as high
as the softening point of the principal polymer component, that
component remains in the form of fibers.
[0021] The low melt bicomponent fibers are selected from a group of
materials consisting of copolyester/polyethylene terephthalate
(CoPET/PET), poly 1,4 cyclohexanedimethyl
terephthalate/polyethylene terephthalate (PCT/PET), poly 1,4
cyclohexanedimethyl terephthalate/polypropylene (PCT/PP),
glycol-modified polyethylene terephthalate/polyethylene
terephthalate (PETG/PET), propylene/polyethylene terephthalate
(PP/PET), nylon 6/nylon 66, polyethylene/glass, or other
combinations of polymers including polymer/glass and
polymer/natural fiber that yield differential melt flow
temperatures. The bicomponent fibers may be any of a variety of
configurations that yield acceptable fiber binding such as
sheath-core, side-by-side, segmented pie, etc. The low melt
bicomponent fibers are described as having a melt flow temperature
of about 100 to 130.degree. C.
[0022] The high melt bicomponent fibers are selected from a group
of materials consisting of copolyester/polyethylene terephthalate
(CoPET/PET), poly 1,4 cyclohexanedimethyl
terephthalate/polyethylene terephthalate (PCT/PET), poly 1,4
cyclohexanedimethyl terephthalate/polypropylene (PCT/PP),
glycol-modified polyethylene terephthalate/polyethylene
terephthalate (PETG/PET), propylene/polyethylene terephthalate
(PP/PET), nylon 6/nylon 66, or other combinations of polymers that
yield differential melt flow temperatures. The bicomponent fibers
may be any of a variety of configurations that yield acceptable
fiber binding such as sheath-core, side-by-side, splitable
segmented pie, etc. The high melt bicomponent is described as
having a melt flow temperature of about 170-200.degree. C.
Bicomponent fibers described as crystalline or semi-crystalline
which have a melt flow temperature of generally about 150 to
180.degree. C. may be substituted in part or whole for the high
melt bicomponent fiber.
[0023] The insulating material provides unique acoustical
insulating properties in combination with the flexural strength of
between about 40-1200 psi. Specifically, the insulating material is
characterized by acoustical absorption coefficients of 0.17-0.24 at
a frequency of 500 Hz, 0.29-0.63 at a frequency of 1000 Hz,
0.50-0.94 at a frequency of 2000 Hz and 0.71-0.99 at a frequency of
4000 Hz all at 2 pcf density. The insulating material also has a
thermal conductivity value of between about 0.20 and 0.30 at 2 pcf
density. Accordingly, it should be appreciated that the insulating
material also provides good thermal insulating properties in
conjunction with good acoustical insulating and structural
properties.
[0024] The staple or bulking fibers utilized in the insulating
material are selected from a group of materials consisting of
polyester fibers, polyethylene fibers, polypropylene fibers, nylon
fibers, rayon fibers, glass fibers, natural fibers and mixtures
thereof.
[0025] The insulating material of the present invention may be
utilized for a number of applications requiring the unique
structural, acoustical insulating and, when appropriate for certain
applications, thermal insulating properties of the present
invention. For example, the insulating material of the present
invention may be utilized in the construction of hood, dash,
firewall or engine cover liners such as shown in FIGS. 1-4 of the
present invention.
[0026] The liner 10 shown in FIG. 1 comprises an acoustical and
thermal insulating layer 12 of the insulating material of the
present invention. More specifically, a single, nonlaminated layer
12 is provided with the necessary mechanical strength and rigidity
to allow easy installation and the desired acoustical and thermal
insulating properties. Advantageously, all of these benefits are
achieved in a light weight liner 10 which may even be used in
compact vehicles where fuel economy concerns lead manufacturers to
seek weight savings wherever possible.
[0027] In a first alternative embodiment shown in FIG. 2, the liner
10 also comprises a single, nonlaminated acoustical and thermal
insulating layer 12 of the insulating material of the present
invention. The layer 12 includes a relatively high density,
nonlaminate or unitary skin 14 of that insulating material along at
least one face thereof. The formation of the relatively high
density, nonlaminate skin 14 of polymer fiber may be completed in
accordance with the process described in detail in co-pending U.S.
patent application Ser. No. 09/607,478, entitled "Process For
Forming A Multi-Layer, Multi-Density Composite Insulator", filed
Jun. 30, 2000 (Owens Corning Case Nos. 24811 and 24812). The full
disclosure of this document is incorporated herein by
reference.
[0028] Advantageously, the high density skin 14 will not delaminate
from the layer 12 under the environmental conditions existing in
the engine compartment and also adds structural integrity and
strength to the liner 10 which aids significantly in handling and
fitting the part during installation. The high density skin 14 is
also more aesthetically pleasing. Still further, for many
applications the high density skin 14 eliminates the need to
provide an additional facing layer of another type of fabric
material. This serves to virtually eliminate any potential for
failure of the lining due to delamination. It also results in a
liner 10 made exclusively of one material that is, therefore, fully
recyclable.
[0029] Further, since the skin may be formed with a hot platen
during the molding of the liner 10 to its desired shape, no
additional processing step is required. This reduces production
costs relative to a liner with a fabric or other facing since such
a facing must be adhere to the acoustical and thermal insulating
layer in a separate processing step.
[0030] In yet another embodiment shown in FIG. 3, the liner 10
includes a single, nonlaminated acoustical and thermal insulating
layer 12 of the insulating material of the present invention in
combination with a facing layer 16 over a first face 18 of the
acoustical and thermal insulating layer. The facing layer 16 may be
constructed from a polymer material selected from a group
consisting of polyester, rayon, polyethylene, polypropylene,
ethylene vinyl acetate, polyvinyl chloride and mixtures
thereof.
[0031] In yet another alternative embodiment shown in FIG. 4, the
liner 10 comprises a single, nonlaminated acoustical and thermal
insulating layer 12 of the insulating material of the present
invention as described above in combination with a first facing
layer 16 covering a first face 18 thereof and a second facing layer
20 covering a second, opposite face 22 thereof. The second facing
layer 20 may be constructed from the same or a different material
as the first facing layer 16. Preferably the first and second
facing layers have a weight of between about 0.50-3.00 ounces per
square yard.
[0032] In accordance with yet another aspect of the present
invention, the acoustical and thermal insulating layer 12 may be a
natural white or include any appropriate form of coloring or
pigment in order to provide a gray or black color. Alternatively,
the acoustical and thermal insulating layer 12 may incorporate any
appropriate color or pigment so as to substantially approximate the
color of the first and/or second facing layers 16, 20 and/or the
paint color of the vehicle. This provides significant aesthetic
benefits. Specifically, when the liner 10 is molded under heat and
pressure in order to nest with the hood, firewall or other
appropriate body panel or superstructure of the engine compartment,
the liner 10 is often subjected to deep drawing at one or more
points. This deep drawing has a tendency to spread the weave of the
fabric facing 16, 20 thereby exposing a portion of the underlying
face 18, 20 of the acoustical and thermal insulating layer to
light. If the acoustical and thermal insulating layer 12 does not
substantially match the color of the facing layer 16, 20 this
creates an undesirable color variation in these deep drawn areas.
In contrast, by matching the color of the layer 12 with the facings
16, 20, this color variation may be substantially eliminated.
[0033] It should further be appreciated that during use the facing
layer 16, 20 may become snagged or subjected to a partial tear
exposing some of the face of the underlying acoustical and thermal
insulating layer 12. Once again, by matching the color of the layer
12 with the facing 16, 20, any color variation is substantially
eliminated and one's attention is not as readily drawn to the
damaged area. Accordingly, an overall improved aesthetic appearance
is maintained over the service life of the liner 10.
[0034] The insulating material of the present invention is produced
in accordance with processing steps generally known in the art.
[0035] The fibers need to be blended in the given ratios and
thermally bonded to form a semi-rigid blanket. The fibers generally
are packaged in 500-700 lb. bales. Each of the three fibers is
generally baled separately although it is possible to get the
fibers from the fiber supplier blended in the proper ratio and
baled together. For purposes of this description, it is assumed
that the fibers come baled separately. Generally each baled fiber
needs to be "opened" by a bale opening system common in the
industry. The opening system fluffs up the fiber and sends the
appropriate amount of fiber by weight to a blending area. This
fluffing serves to decouple the clustered fibrous masses and
enhances fiber-to-fiber contact. The blending area distributes the
different fibers uniformly according to the desired fiber
ratios.
[0036] Once blended the fibers are uniformly distributed on a
conveying system forming an unbonded "sheet" or "blanket" of
uniformly distributed fibers. Thermally activated powdered binders
or other supplemental binding methods may be added during the fiber
blending or conveying stages prior to the sheet entering the
thermal bonding oven. The oven is constructed to allow heated air
to penetrate the fibrous pack and bring the fibers to a temperature
sufficient to activate the binding fibers and/or other binding
materials. If the blanket material is being produced for post
molding applications, the oven temperature need only be high enough
to activate at least some of the low melt binding fibers. The post
mold operation only needs to reach temperatures high enough to
activate the higher melt fibers. If no post mold operation is to
occur then the oven needs to be set to a temperature high enough to
activate both the low melt and high melt fibers--in this case the
required temperature would be at least 180.degree. C. Once the
fibers have reached the appropriate temperature the oven or post
oven area should be capable of reducing the temperature below the
activation point of the binding materials, in this case
approximately below 100.degree. C. The desired thickness of the
blanket is generally established in the oven process. After exiting
the oven, additional binding materials such as powders can be added
to the fibrous blanket or other treatments such as densifying one
or both surfaces of the blanket can occur.
[0037] The blanket can now be handled and utilized "as is" for
structural-acoustical applications or it can be post molded to
produce parts of simple or highly complex shapes. Molding methods
can vary among those typically used in the industry for molding of
thermoplastic materials. One such method is to preheat the blanket
material to a sufficient temperature to (re)activate all of the
binding materials and then quickly transfer the heated blanket to a
cold molding tool and press mold the part until the temperature of
the fibers are below the activation point of the low melt binding
fibers.
[0038] In the case of the samples used for structural testing in
the following example, no post molding operation was utilized to
achieve the desired test thickness.
[0039] The following examples are presented to further illustrate
the invention, but it is not to be considered as limited
thereto.
EXAMPLE
[0040] The structural/acoustical formulation for the insulating
material of the present invention was tested and compared to a
standard formulation of 40% low melt bicomponent having an average
fiber diameter of 14.3 microns, 30% staple (bulking) fiber having
an average fiber diameter of 12.4 microns and 30% staple (bulking)
fiber having an average fiber diameter of 50.0 microns. Together,
the standard formulation had an average fiber diameter of 30.0
microns. Flexural strength testing of the structural/acoustical
formulation of the insulating material of the present invention and
the standard formulation was then run in accordance with ASTM D1037
static three point bend. The results of this testing are clearly
illustrated in FIGS. 5 and 6. FIG. 5 shows the flexural strength of
the two formulations in the machine direction and FIG. 6 shows the
flexural strength of the two formulation in the cross-machine
direction. In both instances, it should be appreciated that the
structural/acoustical formulation of the insulating material of the
present invention provides at least a 100% improvement in elastic
modulus over the standard formulation tested.
[0041] The structural/acoustical formulation of the insulating
material of the present invention also provides acoustical
absorption coefficients somewhat better than those provided by the
standard formulation and as such, provides significant gains in
strength and enhanced acoustical insulating performance. As such,
the present invention represents a significant advance in the
art.
[0042] In summary, numerous benefits result from employing the
concepts of the present invention. An insulating material providing
a unique combination of structural strength, acoustical insulating
and even thermal insulating properties is provided. The insulating
material is particularly suited for use as a hood, dash, firewall
or engine cover liner. It provides the mechanical strength and
rigidity to allow ease in handling and installation while also
providing thermal and acoustical insulating properties that are
consistently and reliably maintained over a long service life even
in the high temperature and high moisture operating environment of
the engine compartment. Such performance characteristics have
heretofore been unavailable in a liner incorporating a single,
nonlaminated layer of acoustical and thermal insulating
material.
[0043] The foregoing description of a preferred embodiment of the
invention has been presented for purposes of illustration and
description. It is not intended to be exhaustive or to limit the
invention to the precise form disclosed.
[0044] The embodiment was chosen and described to provide the best
illustration of the principles of the invention and its practical
application to thereby enable one of ordinary skill in the art to
utilize the invention in various embodiments and with various
modifications as are suited to the particular use contemplated. For
example, crystalline/semicrystalline bicomponent fibers having a
melt flow temperature of about 150.degree. C. to about 180.degree.
C. may be substituted in whole or in part for the high melt
bicomponent fiber. All such modifications and variations are within
the scope of the invention as determined by the appended claims
when interpreted in accordance with the breadth to which they are
fairly, legally and equitably entitled.
* * * * *