Note: Descriptions are shown in the official language in which they were submitted.
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TITLE
IMPROVED NON-WOVEN FIBROUS PRODUCT
BACKGROUND_OF THE INVENTION
The present invention relates to an improved non-woven
fibrous product and more specifically to a non-woven product of
mineral and man-made fibers which exhibits improved strength and
toughness. The man-made, i.e., synthetic, fibers are of two
kinds: standard homogeneous fibers and fibers having a high
melting point core and low melting poink sheath. The blanket may
be formed into sheets, panels and complexly curved and configured
products.
Non-woven fibrous products including shee~s and panels
as well as other thin-wall products such as insulation and
complexly curved and shaped ~tructures formed from such planar
products are known in the art.
In United States Patent No. 2,483,405, two distinct
types of fibers therein designated non-adhesive and potentially
adhesive fibers are utilized to form a non-woven product. The
potentially adhesive fibers typically consist of a thermoplastic
material which axe mixed with non-adhesive fibers to form a
blanket, cord or other produc~ such as a hat. The final product
is formed by activating the potentially adhesive fibers through
the applicakion of heat, pressure or chemical solvents. Such
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activation binds the fibers together and forms a final
product having substantially increased streng-th over the
unactivated product.
United States Patent No. 2,689,199 relates to
non-woven porous, flexible fabrics prepared from masses of
curled, entangled filaments. ~he filaments may be various
materials such as thermoplastic polymers and refractory
fibers of glass, asbestos or steel. A fabric blanket
consisting of curly, relatively short filaments is
compressed and heat is applied to at least one side to
coalesce the fibers into an imperforate film. Thus, a
final product having an imperforate film on one or both
faces may be provided or this product may be utilized to
form multiple laminates. For example, an adhesive may be
applied to the film surface of two layers of the product
and a third layer of refractory fibers disposed between the
film surfaces to form a laminate.
In United States Patent 2,695,855, a felted fibrous
structure which incorporates a rubber-like elastic material
and a thermoplastic or thermosetting resin material is
disclosed. The mat or felt structure includes carrier
fibers of long knit staple cotton, rayon, nylon or glass
fibers, filler fibers of cotton linter or nappers, natural
or synthetic rubber and an appropriate resin. The
resulting structure of fibers intimately combined with the
elastic material and resinous binder is used as a thermal
or acoustical insulating material and for similar purposes.
United States Patent No. 4,568,581 teaches a method of
manufacturing and an article comprising a non-woven blend
of relatively high melting point fibers and relatively low
melting point fibers. At one surface of the article the
low melting point fibers have a fibrous form and at the
opposite surface they exhibit a non-fibrous, fused form.
United States Patent No. 4,612,238 discloses and
claims a composite laminated sheet consisting of a first
layer of blended and extruded thermoplastic polymers, a
particulate filler and short glass fibers, a similar,
second layer of a synthetic thermoplastic polymer,
particulate filler and short glass fibers and a reinforcing
layer of a synthetic thermoplastic polymer, a long glass
fiber mat and particulat~ filler. The first and second
layers include an embossed surface having a plurality of
projections which grip and retain the reinforcing layer to
form a laminate.
One of the inherent difficulties of the non-woven
plural component mat products discussed above relates to
the character and strength of the fiber-to-fiber bonds.
When a thermoplastic resin is utilized, a significant
portion of the resin particles reside in locations within
the fiber matrix where their melting and adhering provide
little or no benefit. This occurs wherever a resin
particle, rather than bridging and securing two adjacent
fibers merely melts on or around a single fiber. Since
there is no way to ensure the emplacement of resin
particles only at fiber junctions, an excess of resin must
be utilized in the blanket in order to assure that
sufficient bonds do develop to produce the re~uisite
strength in the final product. This increases the cost of
the final product. Conversely, not all fiber junctions
receive sufficient resin to create a fiber-to-fiber bond.
Accordingly, unless an excessive amount of thermosetting
resin is added to the fiber blanket, it will not exhibit
the strength and ruggedness theoretically possible because
many junction bonds are absent.
The use of low and high melting po~nt fibers as
suggested in United States Patent No. 2,~83,~05 or
4,568,581 does not entirely solve this difficulty. If the
low melting point fib~r is sufficiently melted to provide
adhesion to another, higher melting point fiber, it may
melt and completely lose its structure. Since low melting
point thermoplastics are typically relatively flexible and
resilient and are utilized in such products for these
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~characteristics, ~he melting and agglomeration of the fiber into
adherent junctions of the other fibers will result in a loss of
resilienca of the product.
It is apparent from the foregoing review of non-woven
mats, blankets and felted structures that variatlons and
improvements in such prior art products are not only possible but
desirable.
SUMMARY OF THE INVENTION
The presen~ invention relates to a non-woven blanket or
mat consisting of a matrix of mineral fibers and man-made fibers.
The mineral fibers are preferably glass fibers. The man-made,
i.e., synthetic, fibers are of two types. The first type may be
conventional, homogeneous solid ox hollow fibers of polyester,
nylon, aramid such as Nomex~or Kevlar or similar synthetic
materials. The second type o~ fibers are bi-component core and
sheath fibers of materials, typically polyesters, having distinct
melting points. A thermosetting resin bonds the fiber matrix
together. A conductive material such as copper or aluminum powder
or a conductive~coloring agent such as carbon black may also be
added and assists static dissipation during manufacture resul~ing
in a product with improved surface finish. Alternatively, the
conductive material may be in the form of fibers.
According to one aspect of the present invention there
is provided a non-woven fibrous product comprising, in
combination, a blended matrix of glass fibers and synthetic
fibers, æaid synthetic fibers including homogeneous fibers
selected from the group consisting of polyester, nylon, Nomex or
Kevlar and bi-component fibers having a core of higher malting
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~temperature polymer and a sheath of lower melting temperature
polymer, and a thermosetting resin dispersed in said matrix
According to a further aspect oP the present invention
there is provided a non-woven fibrous product comprising, in
combination, a homogeneously blended matrix oP glass fihers and
synthetic fibers, said synthetic fibers including homogeneous
fibers selected Prom the group consisting of polyester, nylon,
Nomex or Kevlar and bi-component fibers having a core of higher
melting temperature polymer and a sheath of lower melting
temperature polymer, and a thermosetting resin dispersed in said
matrix.
According to another aspec~t of the present invention
there is provided a non-woven fibrous product comprising, in
combination, a homogeneously blended matrix of glass fibers and
synthetic fibers, said synthetic fibers includiny homogeneous,
~ibers selected from the group consisting of polyester, nylon,
Nomex or Kevlar Pibers and bi-component polyester flbers having a
core of higher melting temperature polyester and a sheath of lower
melting temperature polyester, and a thermosetting resin disposed
in said matrix.
The product consists essentially of fiberized glass
Pibers of three to ten microns in diameter. Such fibers, in an
optimum blend, comprise 66~ by weight of the Pinal product. The
synthetic, homogeneous fibers may be selected from a wide variety
oP materials such as polyesters, nylon , aramids and similar
materials. Larger diameter and/or longer syn~hetic fibers
typically provide more lo~t to the product whereas smaller
diameter and/or shorter iibers produce a denser product. The
optimum propor~lon of synthetic fibers is approximately 12%.
,~ .
by weight. The synthetic, bi-component fibers, consisting
of a core of high melting point polyester surrounded by a
sheath of low melting point polyester comprise about 5~ by
weight of the final product.
A thermosetting resin is dispersed uniformly
throughout the matrix of the mineral and synthetic fibers
and is utilized to bond the fibers together into the final
product configuration. The optimum proportion of the
thermosetting resin is approximately 17% by weight.
If desired, a foraminous or imperforate film or skin
may be applied to one or both surfaces of the blanket
during its manufacture to enhance the surface finish of the
product. Optionally, a conductive coloring agent such as
carbon black or carbon fibers may be included in -the
product. On a total weight basis, the conductive material
preferably constitutes about 1% or less by weight of the
final product.
The density of the product may be adjusted by
adjusting the thickness of the blanket which is initially
formed and the degree to which this blanket is compressed
during subsequent forming processes. Product densities in
the range of from 1 to 50 pounds per cubic foot are
possible.
It is therefore an object of the present invention to
provide a non-woven matrix of glass and homogeneous and
bi-component synthetic fibers having a thermosetting resin
dispersed therethrough.
It is a still further object of the present invention
to provide a non-woven matrix of glass fibers and
homogeneous and bi-component core and sheath synthetic
fibers having a thermosetting resin dispersed therethrough
wherein the sheath of the bi-component fiber may be
activated initially to provide sufficient strength to the
matrix to permit handling and further processing of layers
of distinct rigidity.
It is a still further object of the present invention
to provide a non-woven matrix of glass and homogeneous and
bi-component synthetic fibers having a conductive material
and thermosetting resin dispersed therethrough and a skin
or film on one or both surfaces thereof.
It is a still further object of the present invention
to provide a non-woven matrix of glass fibers, homogeneous
and bi-component synthetic fibers and thermosetting resin
which has its strength and rigidity adjusted by the degree
of activation of the thermosetting resin.
Further objects and advantages of the present
invention will bacome apparent by reference to the
following description of the preferrea and alternate
embodiments and appended drawings.
BRIEF DESCRIPTION_OF THE DRAWINGS
Figure l is an enlarged, diagrammatic view of a
non-woven fiber matrix according to the present invention;
Figure 2A is an enlarged, cross-sectional view of a
hollow, homogeneous fiber utilized in a matrix according to
the present invention;
Figure 2B is an enlarged, cross-sectional view of a
bi-component fiber utilized in a matrix according to the
present invention;
Figure 3 is an enlarged, diagrammatic view of the
fibers of a non-woven fiber matrix according to the present
invention to which thermosetting resin particles have been
added;
Figure 4 is an enlarged, diagrammatic view of a
non-woven fiber matrix according to the present invention
wherein the matrix has been sub~ected to a t~mperature
sufficiently high to melt only the sheath of the
bi--component fiber but not to activate the thermosetting
resin;
Figure 5 is an enlarged, diagrammatic view of a
non-woven fiber matrix according to the present invention
which has been subjected to a temperature sufficiently high
to activate the thermosetting resin;
Figure ~ is an enlarged, diagrammatic view of a first
alternate embodiment of a non-woven fiber matrix product
according to the present invention including conductive
material dispersed therethrough; and
Figure 7 is an enlarged, diagrammatic, fragmentary
side elevational view of a second alternate embodiment of a
non-woven fiber matrix product according to the present
invention having a film disposed on one surface thereof.
DESCRIPTION_OF THE PREFERRED EMBODIMENT
Referring now to Figure 1, an enlarged portion of a
non-woven fibrcus blanket which comprises a matrix of
mineral and man-made fibers according to the present
invention is illustrated and generally designated by the
reference numeral 10. The non-woven ~ibrous blanket 10
includes a plurality of first, mineral fibers 12, second,
homogeneous man-made, i.e., synthetic, fibers 14 and third,
bi-component man-made, i.e., synthetic, fibers 16
homogeneously blended together to form a generally
interlinked matrix.
The first, mineral fibers 12 are preferably glass
fibers. If the fibers 12 are glass fibers, they are
preferably substantially conventional virgin, rotary spun,
fiberized glass fibers having a diameter in the range of
from 3 to 10 microns. The first fibers 12 are utilized in
a dry, i.e., non~resinated, condition. The length of the
individual fibers 12 may vary widely over a range of from
approximately one-half inch or less to approximately 3
inches and depends upon the shredding and processing the
fibers 12 undergo which is in turn dependent upon the
desired characteristics of the final product as will be
s
more fully described subsequently. Other first, mineral
fibers 12 having similar physical properties, i.e. size,
tensile strength, melting point, etc., may also be
utilized.
As illustrated in Figures 1 and 2A, the second,
homogeneous fibers 14 are synthetic, and may be selected
from a broad range of appropriate materials. For example,
polyesters, particularly Dacron polyester, nylons, Kevlar
or Nomex may be utilized. Dacron is a trademark of the E.
I. duPont Co. for its brand of polyester fibers and Kevlar
and Nomex are trademarks of the E. I. duPont Co. for its
brands of aramid fibers. As used in connection with the
second fibers 14, the term "homogeneous" means of uniform
composition and is intended to distinguish the second
fibers 14 from the third, bi-component fibers 16 described
below. The second, homogeneous synthetic fibers 14
preferably define individual fiber lengths of from
approximately one quarter inch to four inches. The
loft/density of the blanket 10 may be adjusted by
appropriate selection of the diameter and/or length of the
synthetic, second fibers 14. Larger and/or longer fibers
in the range of from 5 to 15 denier (approximately 25 to 40
microns) and one to four inches in length provide more loft
to the blanket 10 and final product whereas smaller and/or
shorter fibers in the range of from 1 to 5 denier
(approximately 10 to 25 microns) and one quarter to one
inch in length provide a final product having less loft and
greater density. The second, homogeneous fibers 14 may
likewise be either straight or crimped; straight fibers
providing a final product having less loft and greater
density and crimped fibers providing the opposite
characteristics. The second, homogeneous fibers 14 may
also be hollow and define one or a plurality of axial
passageways 15. The fibers having the passageways 15
exhibit lower lineal weight and higher rigidity than solid
fibers resulting in improved bulk retention.
Referring now to the Figures 1 and 2B, the third,
bi-component synthetic fibers 16 include a core 18 of a
regular melt homopolymer polyester. The polyester core 18
exhibits a melting/bonding temperature of, for e~ample,
485F~ (252C.~ and constitutes approximately 60 percent of
the fiber 16 on a cross sectional and weight basis. The
core 18 is fully surrounded by an annulus or shea~h 20 of a
low melt temperature copolymer polyester. The sheath 20
e~hibits a melting/bonding temperature of, for example,
285E'. (138C~) or, in any event, a temperature
significantly lower, that is, at least about 100 degrees
lower than the melting/bonding temperature of the core 18.
The sheath 20 comprises approximately 40 percent of the
cross section and thus weight of the bi-component fibers
16. A suitable product for use as the bi-component fibers
16 are Dacron polyester core and sheath fibers manufactured
and sold by E.I. du Pont Co. Dacron, as noted, is a
trademark of the E. I. duPont Co.
The bi-component fibers 16 have diameters in the range
of from 1 to 10 denier (approximately 10 to 35 microns~ and
are preferably about 4 denier (approximately 20 microns).
Length of the bi-component fibers 16 may range from less
than about 1 inch to 3 inches and longer.
It should be understood tha~ the melting/bonding
temperatures recited directly above will be inherent
features of the particular homopolymer and copolymer
- chosen. Accordingly, they may vary greatly from the
temperatures given. What is important is that there be a
significant difference between the melting point of the
core 18 and the melting temperature of the sheath 20 and
furthermore that the melting temperature of the sheath 20
be the lower of the two values. So configured, the sheath
20 will melt/bond at a lower temperature than the core 18,
the features and benefits thereof within the context of the
present invention being more fully described subsequently.
~3~
The first, mineral fibers 12, the second, homogeneous
fibers 14 and the third, bi-component fibers 16 are
shredded and blended sufficiently to produce a highly
homogeneous mixture of the three fibers. The mat or
blanket 10 is then formed and the product appears as
illustrated in Figure 1. Typically, the blanket 10 will
have a uniform, initial thickness of between about 1 and 3
inches although a thinner or thicker blanket 10 may be
produced if desired.
Referring now to Figure 3, the blanket 10 also
includes particles of a thermosetting resin 24 dispersed
uniformly throughout the matrix comprising the first,
mineral fibers 12, the second, homogeneous fibers 14, and
the third, bi-component fibers 16. The thermosetting resin
24 may be one of a broad range of general purpose,
engineering or specialty thermosetting resins such as
phenolics, aminos, epoxies and polyesters. The
thermosetting resin 24 functions as a second or final stage
heat activatable adhesive to bond the fibers 12, 14, and 16
together at their points of contact, thereby providing
structural integrity, and rigidity as well as a desired
degree of resiliency and flexibility as will be more fully
described below. The quantity of thermosetting resin 24 in
the blanket 10 directly affects the maximum obtainable
rigidity.
The choice of thermosetting resin 24 also affects
density and loft. For example, shorter flowing
thermosetting resins such as epoxy modified phenolic resins
which, upon the application of heat, quickly li~uify,
generally rapidly bond the fibers 12, 14 and 16 together
throughout the thickness of the blanket 10. Conversely,
longer flowing, unmodified phenolic resins liquify more
slowly and facilitate differential curing of the resin
through the thickness of the blanket 10 as will be
described more fully below.
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Re~erring now to Figure 4, the first or B-stage curiny
of the blanket 10 which produces an intermediate product 26
is illustrated~ As illustrated in Figure 4, the blanket 10
has undergone heating to a temperature in the range of from
about 260F. (1~6C.) to about 300F. (150C.). ~his
initial processing or pre-curing melts the low melting
temperature sheath 20 of the third, synthetic bi-componenk
fiber 16. Instead of being distributed evenly about the
core 18 as illustrated in Figures 2 and 3, the low
melting/bonding temperature copolymer of the sheath 20
flows along the core 18 and agglomerates into junctions or
bonds 28 wherever any of the first, mineral fibers 12 or
second, homogeneous fibers 14 contact or are closely
adjacent the third, bi-component synthetic fibers 16
illustrated in Figure 3. It will thus be appreciated that
the core 18 of the bi-component fibers 16 acts as a carrier
or wick for the low melting -temperature copolymer sheath 20
and, in so doing, facilitates excellent distribution of it
to the other fibers 12 and 14, ensuring a maximum number of
junctions or bonds 28 between such fibers. Furthermore,
the junctions or bonds 28 are formed by the low melting
temperature copolymer resulting in bonds and an
intermediate product 26 which are more resilient and
flexible than bonds and products formed by the bonding of
higher temperature thermoplastics and particularly
thermosetting resins.
Turning now to Figure 5, a final product 32 according
to the instant invention is illustrated. The product 32
has now undergone processing which includes forming in
mating dies to conform the product 32 to a given, final
desired shape and particularly subjecting the matrix of
fibers 12, 14 and 16 and the thermosetting resin 24 -to a
temperature sufficient to activate, i.e., cure, the
particular thermosetting resin 24 utili~ed. Figure 5
illustrates the product 32 in its final form wherein the
particles of thermosetting resin 24 illustrated in the
3%~
preceding Figures have melted and agglomerated into
junctions or bonds 34. Certain of the junctions or bonds
such as the bonds identified by the number 34 generally in
the upper portion of Figure 5 are bonds formed solely of
the thermosetting resin 2~. Th~ thermosetting resin 24
also reinforces the bonds 28 provided by the sheath 20 of
low melting temperature copolymer, as illustrated by the
bonds 34A to the right in Figure 5. The bonds 34A are
bonds of both the copolymer from the sheath 20 of the
bi-component fiber 16 as well as a bond formed by particles
of the thermosetting resin 24. In any event, it will be
appreciated that the melting, activation and curing of tha
thermosetting resin 24 increases the strength alld the
rigidity of the intermediate product 26, thereby forming a
final product 32 having the desired final strength,
rigidity and other structural characteristics.
~ eferring now to Figure 6, a first alternate
embodiment product 36 may include a conductive material 40
dispersed uniformly throughout the matrix comprising the
first, mineral fibers 12, the second, homogeneous fibers 14
and the third, bi-component fibers 16. The conductive
material 40 may be in either fibrous or particulate form.
If the conductive material 40 is in particulate, i.e.
powder, form the particles of conductive material 40 may be
mixed with the fibers 12, 14 and 16, or mixed with the
thermosetting resin 24 prior to application to the blanket
10 or the resin 24 and the particles of conductive material
40 may be applied to the blanket 10 separately.
Alternatively, if in the form of fibers, the conductive
material 40 may be blended with the fibers 12, 14 and 16
when they are blended and formed into the blanket 10.
The particles of conductive material 40 may be
powdered aluminum or copper or carbon black. Other finely
divided or powdered conductive materials, primarily metals,
are also suitable. The carbon black may be like or similar
to Vulcan P or Vulcan XC-72 fluffy carbon black
s
manufactured by the Cabot Corporation. Vulcan is a
trademark of the Cabot Corporation. Pelletized carbon
black may also be utilized but must, of course, be
pulveri~ed before its application to the blanket 10 or
mixing with the thermosetting resin 24 and application to
the blanket 10.
The conductive material 40, if in particulate form and
especially if it is carbon black, changes the appearance of
the product 32, illustrated in Figure 4, from its natural
tan color through grey to silvery black and black depending
upon the relative amount of carbon black added to the
product 32. This color shading and particularly the choice
of the degree of shading is advantageous in the automotive
product market and in applications where the product 32
must be inobtrusive and/or blend with dark surroundings.
Automobile hood liners and similar products are ideal
applications for the product 32 which has been darkened by
the inclusion of carbon black.
The following Table I delineates various ranges as
well as an optimal mixture of the three fibers 12, 14 and
16 and the thermosetting resin 18. The Table sets forth
weight percentages.
TABLE I
Functional Preferred Optimal
Glass Fibers (12)45 - 90 60 - 73 66
Homo, Synthetic Fibers (14) 3 - 30 8 - 18 12.5
Bi-Comp. Synthetic Fibers (1~ 20 3 - 7 4.5
Thermosetting Resin (24) 5 - 40 14 - 20 17
In addition to the foregoing constituents, conductive
material 40 may be added to a maximum weight percentage of
2% and preferably about 1% or less.
~3~3%~
14
A second alternate embodiment 44 of the product 32
according to the present invention is illustrated in Figure
7. Here, the second alternate embodiment product 44,
including the first, mineral fibers 12, the second,
homogeneous synthetic fibers 14, the third, bi-component,
synthetic fibers 18 and the thermosetting resin 24, further
includes a thin skin or film 46. Preferably, the film 46
is adhered to one surface of the product 44 by a suitable
adhesive layer 48. The adhesive layer 48 may be omitted,
however, if sufficient bonding between the blanket 10 and
the film 46 is achieved to satisfy the service requirements
and other considerations of the product 32. The film 46
preferably has a thickness of from about 2 to 10 mils and
may be any suitable material such as spunbonded polyester,
spunbonded nylon as well as a scrim, fabric or mesh
material of such substances. The skin or film 46 may be
either foraminous or imperforate as desired. The prime
characteristics of the film 46 are that it provides both a
supporting substrate and a relatively smooth face for the
product 44, which is particularly advantageous when it
undergoes sequential activation of the bi-component fibers
16 and the thermosetting resin 24 as discussed above. It
is preferable that the skin or film 46 not melt or become
unstable when subjected to the activation temperatures
associated with melting the sheath 20 of the bi-component
fibers 16 of the thermosetting resin 24. It should be
understood that the skin or film 46, though illustrated
onl~ on the face of the product 44, is suitable and
appropriate for use on both faces, if desired.
The products 32, 36 and 44 according to the present
invention provide greatly improved product strength over
previous non-woven fibrous products and fabrication
techniques. The term strength is used its broadest sense
and includes tensile strength, toughness, flexibility and
resistance to puncture. The improvement in these
parameters is primarily the result of the incorporation of
the synthetic, bi-component fibers 16 in the attendant
improvement not only in the total number of bonds 28
achieved between adjacent fibers, that is, between the core
20 of the bi-component fibers 16 and the adjacent first,
mineral fibers 12 and the second, synthetic fibers 14 but
also the flexibility of these joints which are formed from
the low melting temperature copolymer polyester of the
sheath 20. In the final products 32, 36 and 44, wherein
the thermosetting resin 24 has been cured, the relatively
stiff and inflexible of the junctions or bonds 34 formed by
the thermosetting resin 24 and the relatively resilient and
flexible bonds 28 formed from the sheath 20 as well as
bonds 34A formed from both the sheath 20 and thermosetting
resin 24 provide a corresponding combination of qualities,
that is, toughness combining both stiffness and shape
retentivity as well as flexibility and a certain degree of
conformability.
As to the temperatures stated above, it should be
understood that they represent illustrative and relative
temperatures and temperature ranges which relate primarily
to the materials utilized. Generally speaking, however, it
is the relative difference between the melting/bonding
temperatures of the synthetic fibers 14 and 16 and that of
the thermosetting resin 24 which are of most significance.
That is, in order to achieve the appropriate initial
flexible bonding (B-stage curing) provided by the sheath 20
of the bi-component fibers 16 followed by subsequent curing
of the thermosetting resin 24 during the forming of the
final configuration of a product, the melting temperature
of the material of the sheath 20 defines the lowest melting
temperature. Typically, such temperature will be in the
range of from 150 (66C.) to 350F. (177C.). The
melting/curing temperature of the thermosetting resin 24 is
at least 100 and preferably 150F. higher than the melting
temperature of the sheath 20, that is, from 300F. (149C.)
to 550F. (288C.). The melting temperature of the core 18
~.3~
16
of the synthetic, bi-component fiber 16 is desirably at
least 50 and preferably siynificantly more than 50 above
the melting temperature of the chosen thermosetting resin
24 in order that the integrity of the core 18 of the
s~nthetic, bi~component fiber 16 not be damaged by exposure
to excessively high temperatures attendant the curing of
the thermosetting resin 24.
The actual processing temperatures used to melt and
cure the various fibers and resin will, of course, depend
upon the composition of such materials which, in turn,
depend upon the specific application and requirements of
the various products 32, 36 and 44 to be fabricated.
Generally speaking, products including materials having
higher melting points will maintain their structural
integrity at higher service ancl ambient temperatures
whereas products fabricated of fibers and resin having
lower melting temperatures will maintain flexibility at
lower service and ambient temperatures. The foregoing is
illustrative of one of the many parameters which may be
considered in the selection of fibers and thermosetting
resins. Accordingly, neither the temperature range
presented nor the strenyth and application considerations
discussed above should be considered to be limiting or
defining of the present invention in any way.
The foregoing disclosure is the best mode devised by
the inventors for practicing this invention. It is
apparent, however, that products incorporating
modifications and variations will be obvious to one skilled
in the art of non-woven fibrous products. Inasmuch as the
foregoing disclosure is intended to enable one skilled in
the pertinent art to practice the instant invention, it
should not be construed to be limited thereby but should be
construed to include such aforementioned obvious variations
and be limited only by the spirit and scope of the
following claims.
