U.S. patent number RE31,601 [Application Number 06/245,777] was granted by the patent office on 1984-06-12 for composite fabric combining entangled fabric of microfibers and knitted or woven fabric and process for producing same.
This patent grant is currently assigned to Asahi Kasei Kogyo Kabushiki Kaisha. Invention is credited to Masataka Ikeda, Tatsuo Ishikawa, Tsukasa Shima.
United States Patent |
RE31,601 |
Ikeda , et al. |
June 12, 1984 |
Composite fabric combining entangled fabric of microfibers and
knitted or woven fabric and process for producing same
Abstract
The disclosed composite fabric, useful as a substratum for
artificial leather, comprises a woven or knitted frabic and at
least one non-woven fabric firmly bonded to the woven or knitted
fabric, and is produced by providing a precursory sheet with two or
more layers from a woven or knitted fabric and one or more fibrous
webs which consist of numerous extremely fine fibers having an
average diameter of from 0.1 to 6.0 microns, and uniformly
impacting the fibrous web surface of the precursory sheet with
numerous fluid jets ejected under a high pressure of from 15 to 100
kg/cm.sup.2, at a ratio of a total impact area of the fluid jets on
the precursory sheet surface to an area of the precursory sheet
surface to be impacted of at least 1.5, in order to allow the
extremely fine fibers in the fibrous web to randomly entangle with
each other and also to allow a portion of the extremely fine fibers
to penetrate into the inside of the woven or knitted fabric and
entangle with a portion of the fibers in the woven or knitted
fabric.
Inventors: |
Ikeda; Masataka (Nobeoka,
JP), Ishikawa; Tatsuo (Nobeoka, JP), Shima;
Tsukasa (Nobeoka, JP) |
Assignee: |
Asahi Kasei Kogyo Kabushiki
Kaisha (Osaka, JP)
|
Family
ID: |
27309031 |
Appl.
No.: |
06/245,777 |
Filed: |
March 20, 1981 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
826007 |
Aug 19, 1977 |
04146663 |
Mar 27, 1979 |
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Foreign Application Priority Data
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Aug 23, 1976 [JP] |
|
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51-99726 |
Nov 11, 1976 [JP] |
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51-134708 |
Nov 26, 1976 [JP] |
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51-141095 |
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Current U.S.
Class: |
428/93; 28/104;
428/903; 428/96; 428/904; 442/278; 442/280; 442/277 |
Current CPC
Class: |
D04H
1/498 (20130101); B32B 5/26 (20130101); D06N
3/0013 (20130101); D06N 3/0006 (20130101); D06N
3/144 (20130101); D04H 1/43838 (20200501); D06N
3/0011 (20130101); D06N 3/10 (20130101); B32B
5/022 (20130101); D06N 3/106 (20130101); D06N
3/14 (20130101); D04H 1/4382 (20130101); D04H
1/492 (20130101); D06N 3/0004 (20130101); B32B
5/06 (20130101); B32B 5/026 (20130101); D06N
3/0009 (20130101); D04H 1/49 (20130101); B32B
5/024 (20130101); B32B 2260/046 (20130101); Y10T
442/494 (20150401); Y10S 428/903 (20130101); B32B
2262/0261 (20130101); Y10T 442/3772 (20150401); Y10T
442/378 (20150401); B32B 2260/021 (20130101); D06N
2201/0263 (20130101); B32B 2262/0276 (20130101); D04H
1/43835 (20200501); Y10T 428/23964 (20150401); Y10T
442/3805 (20150401); Y10T 428/23986 (20150401); Y10T
442/3789 (20150401); Y10S 428/904 (20130101) |
Current International
Class: |
D04H
13/00 (20060101); D06N 003/00 () |
Field of
Search: |
;428/85,220,219,224,96,238,239,246,252,253,284,287,233,298,299,302,303,903,904
;28/104 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Bell; James J.
Attorney, Agent or Firm: Sprung, Horn, Kramer &
Woods
Claims
What is claimed is:
1. A composite fabric usable as a substratum sheet for artificial
leather and comprising a woven or knitted fabric constituent and at
least one non-woven fabric constituent in an amount of 100% or more
based on the weight of said woven or knitted fabric constituent,
said non-woven fabric constituent having a smooth and even outer
surface and consisting of numerous extremely fine individual fibers
which have an average diameter of 0.1 to 6.0 microns and are
randomly distributed and three-dimensionally entangled with each
other to form a body of non-woven fabric, said non-woven fabric
constituent and said woven or knitted fabric constituent being
superimposed and bonded together, to form a body of composite
fabric in such a manner that a portion of said extremely fine
individual fibers in said non-woven fabric constituent penetrate
into the inside of said woven or knitted fabric constituent and are
entangled with a portion of fibers in said woven or knitted fabric
constituent, and the bonding strength between said woven or knitted
fabric constituent and said non-woven fabric constituent being at
least 30 g/cm.
2. A composite fabric as claimed in claim 1, wherein said woven or
knitted fabric constituent is interposed between two non-woven
fabric constituents.
3. A composite fabric as claimed in claim 1, wherein one non-woven
fabric constituent is superimposed on one woven or knitted fabric
constituent.
4. A composite fabric as claimed in claim 1, wherein said extremely
fine individual fibers in said non-woven fabric constituent are
produced from a synthetic polymer by using a melt blow process and
are substantially free from melt-bonding to each other.
5. A composite fabric as claimed in claim 1, wherein said extremely
fine individual fibers in said non-woven fabric constituent are
three-dimensionally entangled with each other, and penetrate and
three-dimensionally entangle with a portion of the fibers in said
woven or knitted fabric constituent by using the action of numerous
liquid jets ejected under a high pressure toward said non-woven
fabric constituent placed on said woven or knitted fabric
constituent.
6. A composite fabric as claimed in claim 1, wherein said extremely
fine individual fibers consist of a polyester or a polyamide.
7. A composite fabric as claimed in claim 1, wherein said non-woven
fabric constituted had a density of from 0.10 to 0.30 g/cm.sup.3
and a tensile strength of from 0.10 to 0.30 kg/mm.sup.2.
8. A composite fabric as claimed in claim 1, wherein the total
weight of said at least one non-woven fabric constituent is in a
range from 80 to 300 g/m.sup.2.
9. A composite fabric as claimed in claim 1, wherein said woven or
knitted fabric constituent has a weight of from 20 to 80
g/m.sup.2.
10. A composite fabric as claimed in claim 1, wherein the total
weight of said at least one non-woven fabric constituent is in a
range of from 200 to 800% based on the weight of said woven or
knitted fabric constituent.
11. A composite fabric as claimed in claim 1, wherein said bonding
strength between said woven or knitted fabric constituent and said
non-woven fabric constituent is in a range of from 50 to 250
g/cm.
12. A composite fabric as claimed in claim 1, wherein said
composite fabric has an average density of from 0.15 to 0.32
g/cm.sup.3 and a tensile strength of from 0.5 to 1.8
kg/mm.sup.2.
13. A composite fabric as claimed in claim 1, wherein numerous
piles consisting of said extremely fine individual fibers are
formed on the surface of said non-woven fabric constituent.
14. A composite fabric as claimed in claim 1, wherein said
composite fabric is impregnated with a rubber-like elastic polymer
and the non-woven fabric constituent surface of said impregnated
composite fabric is raised.
15. A composite fabric as claimed in claim 14, wherein said elastic
polymer is polyurethane.
16. A composite fabric as claimed in claim 14, wherein said elastic
polymer is present in an amount of from 20 to 70%, based on the
total weight of said composite fabric.
17. A composite fabric as claimed in claim 13, wherein said
extremely fine piles have an average length of from 0.05 to 1.0
mm.
18. A composite fabric as claimed in claim 1, wherein said
composite fabric has an area shrinkage of from 5 to 20% in boiling
water.
19. A process for producing a composite fabric usable as a
substratum sheet for artificial leather, comprising:
forming a fibrous web constituent by randomly massing numerous
extremely fine individual fibers having an average diameter of from
0.1 to 6.0 microns;
forming a multilayer precursory sheet by superimposing a woven or
knitted fabric constituent and at least one said fibrous web
constituent on each other,
jetting numerous fluid streams ejected under a pressure of from 15
to 100 kg/cm.sup.2 toward the surface of said fibrous web
constituent of said percursory sheet, at a ratio of a total impact
area of said fluid jets on said percursory sheet surface to an area
of said precursory sheet surface to be impacted of at least 1.5, to
convert said fibrous web into a non-woven fabric constituent in
which said extremely fine individual fibers are randomly entangled
with each other and to convert said precursory sheet into a
composite fabric in which said non-woven fabric constituent is
bonded to said woven or knitted fabric constituent in such a manner
that a portion of said extremely fine individual fibers penetrate
from said non-woven fabric constituent into the inside of said
woven or knitted fabric constituent and are entangled with a
portion of the fibers within said woven or knitted fabric
constituent, and;
at the same time as said fluid stream jetting operation, applying a
reduced pressure of 10 to 200 mmHg onto a surface of said
precursory sheet opposite to said fibrous web surface.
20. A process as claimed in claim 19, wherein said fluid stream
jetting operation is carried out in at least two successive steps
in such a manner that each fluid stream jet in a preceding jetting
step impacts against said precursory sheet in an impact area
smaller than that in a succeeding step and the impacting force of
each fluid stream jet in a preceding jetting step is at least ten
times that in a succeeding step, in order to eliminate holes and
densts formed on said precursory sheet surface by the action of
said fluid stream jets in the preceding step. .Iadd. 21. An
extremely fine fiber fabric usable as a substratum sheet for an
artificial leather, comprising at least one non-woven fabric
constituent having a smooth and even outer surface and consisting
of numerous extremely fine individual fibers which have an average
diameter of 0.1 to 6.0 microns and are randomly distributed and
three-dimensionally entangled with each other to form a body of
non-woven fabric. .Iaddend. .Iadd. 22. A fabric as claimed in claim
21, wherein said extremely fine individual fibers in said non-woven
fabric constituent are produced from a synthetic polymer by using a
melt blow process and are substantially free from melt-bonding to
each other. .Iaddend..Iadd. 23. A fabric as claimed in claim 21,
wherein the three-dimensional entanglement of said extremely fine
individual fibers is formed by using the action of numerous liquid
jets ejected under a high pressure toward said non-woven fabric
constituent. .Iaddend..Iadd. 24. A fabric as claimed in claim 21,
wherein said extremely fine individual fibers consist of a
polyester or a polyamide. .Iaddend..Iadd. 25. A fabric as claimed
in claim 21, wherein said non-woven fabric constituent had a
density of from 0.10 to 0.30 g/cm.sup.3 and a tensile strength of
from 0.10 to 0.30 kg/mm.sup.2. .Iaddend..Iadd. 26. A fabric as
claimed in claim 21, wherein the total weight of said at least one
non-woven fabric constituent is in a range from 80 to 300
g/m.sup.2. .Iaddend..Iadd. 27. A fabric as claimed in claim 21,
wherein numerous piles consisting of said extremely fine individual
fibers are formed on the surface of said non-woven fabric
constituent. .Iaddend. .Iadd. 28. A fabric as claimed in claim 21,
wherein said fabric is impregnated with a rubber-like elastic
polymer and the surface of said impregnated fabric is raised.
.Iaddend..Iadd. 29. A fabric as claimed in claim 28, wherein said
elastic polymer is polyurethane. .Iaddend..Iadd. 30. A fabric as
claimed in claim 28, wherein said elastic polymer is present in an
amount of from 20 to 70%, based on the weight of said fabric.
.Iaddend..Iadd. 31. A fabric as claimed in claim 27, wherein said
extremely fine piles have an average length of from 0.05 to 1.00
mm. .Iaddend.
Description
The present invention relates to a composite fabric and a process
for producing the same. More particularly the present invention
relates to a composite fabric usable as a substratum sheet for
artificial leather and comprises at least one non-woven fabric
constituent and a woven or knitted fabric constituent firmly bonded
to form a body of a composite fabric, and a process for producing
the composite fabric.
It is known that natural leather is composed of numerous collagen
fiber bundles. When the back side surface of the natural leather is
buffed to provide a pile surface layer, the resultant product is a
suede leather. Also, when the grain side surface is buffed, the
resultant product is a so-called nubuck leather. The buffed surface
of the nubuck leather consists of very thin collagen fiber
piles.
Generally, artificial leather is produced by impregnating a
substratum sheet consisting of a non-woven fabric with an elastic
polymer material, for example, polyurethane and butadiene-styrene
rubber. If desired, the artificial leather is buffed to convert it
into a suede or nubuck-like artificial leather. Accordingly, in
order to prepare an artificial leather having a nubuck-like buffed
surface, it is important that numerous piles consisting of
extremely fine individual fibers are formed at a high density on
the surface of the artificial leather, the surface of the
artificial leather has a writing effect like that of the natural
nubuck leather, and the artificial leather has a high softness and
a proper draping property. The artificial leather is also required
to have a high resistance to breakage even if the artificial
leather has a small thickness of 1 mm or less.
Accordingly, there have been various atempts made to obtain an
artificial leather satisfying the above-mentioned requirements. For
example, Japanese Patent Application Publication No. 49-48583(1974)
(corresponding to U.S. Pat. No. 3,932,687) discloses a non-woven
fabric composed of fibrous bundles of fine fibers having a denier
of 1.5 or less. The non-woven fabric is prepared from special
composite fibers, that is, inland-in-sea type composite fibers. In
the preparation of an artificial leather from this non-woven
fabric, the non-woven fabric is impregnated with an elastic polymer
and, then, the fibrous bundles located on the surface portion of
the non-woven fabric are raised to form numerous piles. However,
this type of the non-woven fabric has a relatively low density
because the sea components are removed from the composite fibers in
order to convert the composite fibers into the fiber bundles.
Therefore, the density of the piles formed on the artificial
leather is also relatively low. In the case where the piles are
relatively short, portions of the raised surface of the artificial
leather are occupied with the elastic polymeric material and,
therefore, the resultant artificial leather exhibits a rough
appearance and a gritty feel. Furthermore, this type of artificial
leather, having a small thickness of 1 mm or less, has poor tensile
and tear strengths due to the fact that the substratum is composed
of a non-woven fabric in which the fiber bundles are randomly
entangled. Especially, the thin artificial leather has a very poor
resistance to breakage at the seams thereof, in which seams
portions of the artificial leather are strongly and frequently
flexed while the artificial leather is being worn or processed.
Further, in the process for producing the above-mentioned
conventional type of artificial leather, the islands-in-sea type
composite filaments are crimped by using a crimping machine, and
cut to form a desired length of staple fibers. Then, the staple
fibers are formed into a random web by using a random webber and
the random web is needle punched to convert it into a precursory
non-woven fabric. Thereafter, the sea component is removed from the
precursory non-woven fabric so as to convert it into a final
non-woven fabric composed of the island component fiber bundles.
The above-mentioned process for producing the final non-woven
fabric involves an undesirable chemical treatment for removing the
sea component and is very complicated and expensive.
Japanese Patent Application Publications No. 41-3759(1966) and No.
51-6261(1976) disclose a non-woven fabric usable as a substratum of
the artificial leather. This type of non-woven fabric is composed
of fibrous bundles of extreamly fine fibers or porous fibers having
a honeycomb-like cross-sectional profile. This non-woven fabric is
produced by providing composite fibers from a blend of at least two
types of component polymers and removing at least one component
polymer from the composite fibers after forming a precursory
non-woven fabric from the composite fibers. This process also
involves the undesirable chemical treatment for removing the
component polymer and is very complicated and expensive.
Japanese Patent Application Publication No. 41-21475(1966)
discloses a non-woven fabric usable as a substratum for suede-like
artificial leather. The non-woven fabric is prepared by providing a
random web from a mixture of staple fibers having a denier of 0.5
(a cross-sectional diameter of about 7 microns) and crimped staple
fibers having a denier of 1.5, and needle-punching the random web
to convert it into a non-woven fabric. However, this type of
non-woven fabric can not be provided with uniform piles in a high
density and, therefore, can not have a good writing property that
is, chalk mark-forming property. Therefore, the raised artificial
leather produced by using the above-mentioned non-woven fabric as a
substratum, is quite different in appearance from natural nubuck
leather and has a poor density, tensile and tear strengths and
dimentional stability because the substratum is composed of only
the non-woven fabric having a poor density, tensile and tear
strengths and dimensional stability.
Japanese Patent Application Laying-open No. 50-121570(1975)
discloses a process for producing a composite fabric. In this
process discontinuous extremely fine fibers are produced in a
melt-blow method and are directly blown toward a woven or knitted
fabric by action of fluid jets. In the initial stage of the blowing
step, a portion of the blown fibers can penetrate into the inside
of the woven or knitted fabric. However, after the surface of the
woven or knitted fabric is covered by a stratum of the extremely
fine fibers, the extremely fine fibers can not penetrate into the
inside of the woven or knitted fabric and, therefore, the
combination of the woven or knitted fabric with the stratum of the
extremely fine fibers can not be proceeded any more. Particularly,
when the stratum of the extremely fine fibers becomes a weight of
20 g/m.sup.2 or more, the blown extremely fine fibers are
completely unable to penetrate into the woven or knitted fabric
through the stratum of the extremely fine fibers. Therefore, the
stratum of the extremely fine fibers is bonded to the woven or
knitted fabric with a very poor bonding strength of 10 g/cm or
less. Further, in the stratum of the extremely fine fibers produced
in accordance with this type of process, the extremely fine fibers
are distributed only in two dimentions, and can not be randomly
distributed in three dimensions and entangled with each other with
a high degree of entanglement.
That is, this type of process can not convert the stratum of the
extremely fine fibers into a non-woven fabric. Accordingly, the
resultant composite fabric has a poor bulkiness and recovery from
compression. When this composite fabric is utilized as a substrate,
the resultant artificial leather has an undesirable paper-like
appearance and feel, and can not provide piles formed in a high
density on the surface thereof. Also, the surface of the artificial
leather has a very poor resistance to abrasion. Therefore, this
type of composite fabric is can not be utilized for producing
nubuck-like artificial leather. Additionally, when the fibers
produced by the melt-blow method adhere to each other, the
resultant composite fabric has an undesirable relatively high
stiffness.
An object of the present invention is to provide a composite fabric
capable of providing a pile layer consisting of extremely fine
fibers existing at a high density and useful as a substratum sheet
for a nubuck-like artificial leather having a desirable chalk
mark-forming property.
Another object of the present invention is to provide a composite
fabric usable as a substratum sheet for artificial leather having a
proper softness and being useful as a material for clothing, and a
process for producing the same.
Still another object of the present invention is to provide a
composite fabric usable as a substratum sheet for artificial
leather having high resistances to breakage and abrasion, a high
dimensional stability, and a process for producing the same.
The above-mentioned objects can be attained by the composite fabric
of the present invention which comprises a woven or knitted fabric
constituent and at least one non-woven fabric constituent, in an
amount of 100% or more based on the weight of said woven or knitted
fabric constituent, and consisting of numerous extremely fine
individual fibers which have an average diameter of 0.1 to 6.0
microns and are randomly distributed and entangled with each other
to form a body of non-woven fabric, said non-woven fabric
constituent and said woven or knitted fabric constituent being
superimposed and bonded together, to form a body of composite
fabric, in such a manner that a portion of said extremely fine
individual fibers in said non-woven fabric constituent penetrate
into the inside of said woven or knitted fabric constituent and are
entangled with a portion of fibers in said woven or knitted fabric
constituent, and the bonding strength between said woven or knitted
fabric constituent and said non-woven fabric constituent is at
least 30 g/cm.
The above-mentioned composite fabric can be produced by using the
process of the present invention which comprises:
forming a fibrous web constituent by randomly massing numerous
extremely fine individual fabrics having an average cross-sectional
diameter of from 0.1 to 6.0 microns;
forming a multilayer precursory sheet by superimposing a woven or
knitted fabric constituent and at least one said fibrous web
constituent on each other;
jetting numerous fluid streams ejected under a pressure of from 15
to 100 kg/cm.sup.2 toward the surface of said fibrous web
constituent of said precursory sheet at a ratio of a total impact
area of said fluid jets on the precursory sheet surface to an area
of the precursory sheet surface to be impacted of at least 1.5, to
convert said fibrous web into a non-woven fabric constituent in
which said extremely fine individual fibers are randomly entangled
with each other and to convert said precursory sheet into a
composite fabric in which said non-woven fabric constituent is
bonded to said woven or knitted fabric constituent in such a manner
that a portion of said extremely fine individual fibers penetrate
from said non-woven fabric constituent into the inside of said
woven or knitted fabric constituent and are entangled with a
portion of the fibers within said woven or knitted fabric
constituent. The above-mentioned conversions of the fibrous web
into the non-woven fabric constituent and of the precursory sheet
into the composite fabric is promoted by applying a reduced
pressure of 10 to 200 mmHg onto a surface of said precursory sheet
opposite to the fibrous web surface.
Further features and advantage of the present invention will be
apparent from the following description, with reference to the
accompanying drawings, wherein:
FIG. 1 is a cross-sectional model view of an internal structure of
natural leather;
FIG. 2 is an explanatory view of a cross-sectional profile of a
conventional artificial leather using fibrous bundles of extremely
fine fibers;
FIG. 3 is an explanatory view of a cross-sectional profile of a
three constituent composite fabric of the present invention;
FIG. 4 is an explanatory view of a cross-sectional profile of a two
constituent composite fabric of the present invention;
FIG. 5 is an explanatory view of a cross-sectional profile of an
artificial leather produced by using a composite fabric of the
present invention and having a pile layer;
FIG. 6 is a schematic view of an apparatus for ejecting numerous
high velocity fluid streams toward a precursory sheet;
FIG. 7 is a cross-sectional view of an orifice through which the
high velocity fluid stream is ejected;
FIG. 8 is an explanatory view of a specimen of the composite fabric
of the present invention for testing the bonding strength between
the woven- or knitted fabric constituent and the non-woven fabric
constituent;
FIG. 9A is an explanatory view of a specimen of the composite
fabric of the present invention, for testing the tear strength
thereof;
FIG. 9B is an explanatory view of a specimen of the composite
fabric of the present invention in a posture for testing a tear
strength thereof, and;
FIG. 10 is an explanatory view of a specimen of the composite
fabric of the present invention for testing its sewing
strength.
Referring to FIG. 1, which shows the internal structure of natural
leather, numerous collagen fiber bundles, which vary in thickness,
are entangled with each other. That is, the collagen fiber bundles
located in the back side surface portion of natural leather have a
relatively large thickness and are composed of relatively thick
individual collagen fibers. However, the grain side surface portion
of natural leather is composed of numerous very thin collagen fiber
bundles and very thin individual collagen fibers.
Accordingly, in a suede leather, which is prepared by buffing the
back side surface of the leather, the buffed surface is covered
with numerous piles consisting of the relatively thick collagen
fiber bundles spaced from each other. Compared with suede leather,
in a nubuck leather, which is produced by buffing the grain side
surface of the leather, the piles covering the buffed surface
consist of very thin collagen fiber bundles and very thin collagen
individual fibers standing close to each other. Consequently, in
order to obtain an artificial leather having a nubuck-like buffed
surface, it is important that the piles consisting of very thin
fiber bundles and very fine individual fibers be formed in a high
density.
Referring to FIG. 2, showing an internal structure of a
conventional artificial leather, numerous fiber bundles, having a
relatively large thickness, are randomly entangled, and the piles 4
formed on the buffed surface thereof are spaced from each other.
That is, the piles are formed at a relatively low density.
Accordingly, a portion of an elastic polymer 5 impregnated between
the fiber bundles 3 is sometimes not completely covered with the
piles. This results in an artificial leather of low quality.
The composite fabric of the present invention has a cross-sectional
structure as explanatorily shown in FIG. 3 or 4. Referring to FIG.
3, the composite fabric 10 is composed of a woven or knitted fabric
constituent 11 embedded between an upper non-woven fabric
constituent 12 and a lower non-woven fabric constituent 13. In each
non-woven fabric constituent, numerous extremely fine fibers 14 are
randomly entangled with each other in three dimensions. Further,
portions of the extremely fine fibers penetrate from the non-woven
fabric constituents 12 and 13 into the inside of the knitted or
woven fabric constituent 11, and entangle with a portion of the
fibers 15 in the woven or knitted fabric constituent 11.
Accordingly, the non-woven fabric constituents 12 and 13 are firmly
bonded to the woven or knitted fabric constituent 11 to form a body
of composite fabric.
Referring to FIG. 4, a non-woven fabric constituent 16 is
superimposed on and firmly bonded to a woven or knitted fabric
constituent 17 in the same manner as mentioned above.
Referring to FIG. 5, an artificial leather 20 is composed of a
composite fabric, as a substratum, impregnated with an elastic
polymer 21. The composite fabric has the same internal structure as
that indicated in FIG. 3, except that the surface layer of the
upper non-woven fabric constituent 12 is buffed so as to form a
pile layer 22. The pile layer 22 consists of numerous extremely
fine fibers 14 uniformly distributed in a high density. That is,
the extremely fine fibers 14 are independent from each other but
not be formed into fiber bundles.
The extremely fine fibers usable for the composite fabric of the
present invention have an average diameter of 0.1 to 6.0 microns,
which corresponds to a denier in a range of about 0.0001 to about
0.35. A diameter smaller than 0.1 microns will result in a very
poor tensile strength of the resultant extremely fine fiber. Also,
a diameter greater than 6 microns will cause the resultant
composite fabric to have a poor softness and the resultant
artificial leather to have a poor chalk mark-forming property due
to a low density of the fibers located in the pile layer.
The artificial leather having a nubuck-like appearance, feel and
chalk mark-forming property can be obtained by utilizing the
composite fabric of the present invention, in which the non-woven
fabric constituent is composed of extremely fine fibers with a
diameter of 0.1 to 6.0 microns, preferably, 0.5 to 3.0 microns,
more preferably, 1.0 to 2.0 microns.
The extremely fine fibers usable for the present invention are not
limited to a specified group of polymers as long as the polymers
are capable of forming the extremely fine fibers having the
specified diameter. For example, the extremely fine fibers may
consist of a regenerated cellulose, for instance, viscose rayon,
and cuprammonium rayon, or a synthetic polymer, for instance,
polyester, polyamide, polyolefin polyacrylonitrile, a copolymer of
two or more of the monomers for forming the above-mentioned
polymers or a mixture of two or more of the above-mentioned
polymers. The polyamides involve nylon 6, nylon 66, nylon 10, nylon
11, nylon 12, a copolymer of nylon 6 with nylon 66, a copolymer of
nylon 6 with nylon 10, a copolymer of nylon 6 with isophthalamide,
a copolymer of nylon 6 with polyoxyethylene-di-amine, a copolymer
of nylon 66 with polyoxyethylene-di-amine, a blend polymer of nylon
66 and polyethyleneglycol, a blend of nylon 6 and
polyethyleneglycol, a blend of nylon 6 or nylon 66 and at least one
of the copolymers described above, and an aromatic polyamide such a
polymethaphenylene tetraphthalamide and poly-N-methyl-phenylene
tetraphthalamide.
The polyesters may be polyethylene terephthalate, a polyethylene
terephthalate-isophthalate copolymer, a polyethylene
terephthalate-adipate copolymer, a polyethylene
terephthalate-trimediate copolymer, a polyethylene
terephthalate-sebacate copolymer, a polyethylene
terephthalate-succinate copolymer, a polyethylene-diethylene glycol
terephthalate copolymer, a polyethylene-ethylene glycol
terephthalate copolymer or a mixture of two or more of the
above-mentioned polymers.
The polyacrylic polymers may be polyacrylonitrile, a copolymer of
acrylonitrile with at least one member selected from methyl
acrylate, methyl methacrylate and ethyl acrylate, or a mixture of
two or more of the above-mentioned polymers.
The polyolefins may be polyethylene, polypropylene or a mixture of
polyethylene and polypropylene.
The extremely fine fibers can be produced by using any of the
conventional fiber-producing methods. Preferably, the extremely
fine fibers are produced from a thermoplastic synthetic polymer by
using a melt-blow method. In order to produce a nubuck-like
artificial leather, it is more preferable that the extremely fine
fibers are produced from polyethylene terephthalate by using the
melt-blow method. This is because the polyethylene terephthalate
fibers have a proper shrinkage which is effective for forming the
pile layer having a high density.
In the composite fabric, it is desired that the extremely fine
fibers in the non-woven fabric constituent are three dimensionally
entangled with each other at a proper degree of entanglement. That
is, the extremely fine fibers should be entangled with each other
to such an extent that the resultant non-woven fabric constituent
has a density of 0.10 to 0.30 g/cm.sup.3, more preferably, 0.15 to
0.28 g/cm.sup.3, and a tensile strength of 0.10 to 0.30
kg/mm.sup.2, more preferably, 0.12 to 0.26 kg/mm.sup.2. Further, it
is desired that the bonding of at least one non-woven fabric
constituent with the woven or knitted fabric constituent will
result in a composite fabric having an average density of 0.15 to
0.32 g/cm.sup.3, more preferably 0.18 to 0.30 g/cm.sup.3, and a
tensile strength of 0.5 to 1.8 kg/mm.sup.2, more preferably, 0.7 to
1.5 kg/mm.sup.2.
When a composite fabric is impregnated with an elastic polymer and
buffed on a surface thereof, a non-woven fabric constituent having
a density lower than 0.10 g/cm.sup.3 and a tensile strength lower
than 0.10 kg/mm.sup.2 will cause the resultant artificial leather
to have a paper-like appearance and feel, and a pile layer having a
poor density. Also, the utilization of a non-woven fabric
constituent having a density greater than 0.30 g/cm.sup.3 and a
tensile strength higher than 0.30 kg/mm.sup.2 will result in an
artificial leather which is poor in natural leather-like softness,
draping property and resilience.
In the composite fabric of the present invention, it is required
that at least one non-woven fabric constituent be in a total amount
of at least 100%, preferably, at least 150%, more preferably, 200
to 800%, based on the weight of the woven or knitted fabric
constituent. The total amount of less than 100% of the non-woven
fabric constituent will result in an extremely poor resilience,
compressibility and recovery from compression and a very low
bulkiness of the resultant composite fabric. Further, the
excessively small amount of the non-woven fabric constituent will
cause the resultant composite fabric to exhibit the disadvantage
that the non-woven fabric constituent can not completely cover the
woven or knitted fabric constituent and, therefore, a portion of
the woven or knitted fabric constituent appears on the surface of
the non-woven fabric constituent layer. Such appearance of the
composite fabric can not be utilized as a substratum for the
artificial leather.
In order to produce an artificial leather useful as a material for
clothing, the composite fabric is required to have a high softness
and resiliency. In order to meet this requirement, it is preferably
that the non-woven fabric constituent has a total weight of 50 to
200 g/m.sup.2, more preferably, 80 to 250 g/m.sup.2, still more
preferably, 100 to 200 g/m.sup.2.
The extremely fine fibers in the non-woven fabric constituent are
required not only to randomly and three-dimensionally entangle with
each other with a high degree of entanglement, but a portion of the
extremely fine fibers are required to penetrate into the inside of
the woven or knitted fabric constituent and entangle with a portion
of the fibers in the woven or knitted fabric constituent to such an
extent that both of the constituents are firmly bonded to each
other with a bonding strength of 30 g/cm or more.
The higher the degree of entanglement of the extremely fine fibers,
penetrated from the non-woven fabric constituent, with the fibers
in the woven or knitted fabric constituent, the higher the bonding
strength between both the constituents. A bonding strength of 30
g/cm or more is sufficient to unite the non-woven fabric
constituent and the woven or knitted fabric constituent into a body
of composite fabric having a proper density. In the case where the
bonding strength is lower than 30 g/cm, the resultant composite
fabric tends to be easily divided into the separate constituents
while the composite fabric is processed, and also tends to form a
paper-like artificial leather having a poor resiliency in spite of
impregnation of the composite fabric with an elastic polymer.
In order to provide an artificial leather useful as a material for
clothing, the composite fabric to be used as a substratum is
required to have not only a high tensile strength, resiliency and
bulkiness, but also a high softness. In order to satisfy these
requirements, it is preferable that the bonding strength between
the non-woven fabric constituent and the woven or knitted fabric
constituent be in a range of from 50 to 250 g/cm, more preferably,
70 to 200 g/cm. The bonding strength is determined in accordance
with a method which will be explained in detail hereinafter.
The woven or knitted fabric usuable as a constituent of the
composite fabric of the present invention is required to have a
density of weaving or knitting structure which allow the fabric to
have spaces formed between the fibers or yarns, which spaces are
large enough to receive the portion of the extremely fine fibers
penetrated from the non-woven fabric constituent into inside of the
woven or knitted fabric constituent. That is, it is preferable that
the woven or knitted fabric has a weight of 10 to 100 g/m.sup.2,
more preferably, 20 to 80 g/m.sup.2, still more preferably, 30 to
60 g/m.sup.2. A very thin woven or knitted fabric having a weight
smaller than 10 g/m.sup.2 and a low density is sometimes difficult
to uniformly open without the formation of wrinkles. The resultant
composite fabric from the thin woven or knitted fabric has poor
tensile and tear strengths. Also, a very thick woven or knitted
fabric with a weight of 100 g/m.sup.2 and a high density is
sometimes difficult to firmly bond to the non-woven fabric due to
the difficulty in the penetration of the extremely fine fibers from
the non-woven fabric into woven or knitted fabric.
The fibers in the woven or knitted fabric constituent may consist
of the same as or different from that of the extremely fine fibers.
That is the woven or knitted fabric constituent may be composed of
viscose rayon fibers, cuprammonium rayon fibers, cellulose acetate
fibers, polyamide fibers, polyester fibers, polyacrylic fibers,
polyolefin fibers or the like. The woven or knitted fabric
constituent may be composed of a mixture of two or more of the
above-mentioned types of fibers, for example, a mixture of the
viscose of cuprammonium rayon fibers and the polyamide fibers or a
mixture of the polyester fibers and the polyamide fibers. The
fibers in the woven or knitted fabric constituent preferably have a
denier of 5 or less, more preferably, 0.2 to 3. If the denier of
the fibers is excessively large, the resultant composite fabric
will create a high stiffness in the artificial leather prepared
from the composite fabric. Further, it is preferable that the yarns
from which the woven or knitted fabric is formed have a total
denier of 150 or less, more preferably, 100 or less, still more
preferably, 70 or less.
The woven or knitted fabrics usable for the composite fabrics of
the present invention are not restricted to a specific class of
fabrics, and can include various types of knitted fabrics, for
example, plain stitch fabrics, warp knitted fabrics, warp knitted
fancy fabrics, weft knitted fabrics, for instance, tricot fabrics,
weft knitted fancy fabrics and laces, as well as various types of
woven fabrics, for example, plain weave fabrics, twill fabrics,
stain fabrics and figured cloths.
In the preparation of the composite fabric of the present
invention, a fibrous web consisting of extremely fine fibers is
arranged on a surface of a woven or knitted fabric constituent and,
if necessary, another fibrous web consisting of the extremely fine
fibers is arranged on the opposite surface of the woven or knitted
fabric to provide a precursory sheet. The precursory sheet is,
then, subjected to a treatment with high speed fluid stream jets to
convert the precursory sheet into a body of composite fabric.
The fibrous web can be prepared from the extremely fine fibers by
using any of the conventional methods. However, it is preferable
that the fibrous web be produced by using a melt-blow method or a
paper-making method. The melt-blow method may be the one disclosed
in Japanese Patent Application Laying-open No. 50-46972(1975). In
this method, a melted thermoplastic fiber-forming polymer is
extruded through numerous spinning orifices arranged in a row into
a high speed stream of a gas. The resultant discontinuous extremely
fine fibers are blown onto a screen conveyer, continuously
forwarded in one direction below the spinning orifices, and
accumulated on the screen conveyer to form a fibrous web. In the
preparation of the fibrous web in the melt-blow method, it is
important to uniformly distribute the resultant fibers on the
screen while preventing melt-adhering of the resultant individual
fibers to each other. That is, it is important, in order to easily
convert the fibrous web into a non-woven fabric, that the
individual fibers be independent from each other and free in
movement in relation to each other. For the above-mentioned
purpose, it is desirable that the distance between the screen and
the orifices be in a range of 20 to 60 cm, more preferably, 30 to
55 cm. The fibrous web produced by the melt-blow method, is
composed of extremely fine independent fibers which do not form
fibrous bundles. In the web, the fibers are laid down along the
surface of the web and entangled with each other in a low degree of
entanglement. However, the fibers can not substantially extend in a
direction at a right angle to the web surface and, also, can not
entangle with each other in this direction. The degree of
entanglement of the fibers can be expressed in terms of the tensile
strength and density of the fibrous web. Usually, the fibrous web
produced in the melt-blow method, has a tensile strength of about
0.01 kg/mm.sup.2 and a density of from 0.02 to 0.05 g/cm.sup.3.
Even if the fibrous web is compressed to increase the density of
the web to about 0.2 g/cm.sup.3, the resultant compressed web still
has a poor tensile strength of about 0.05 kg/mm.sup.2. This
phenomenon illustrates the fact that, in the fibrous web produced
by using the melt-blow method, the fibers are entangled with each
other at a very low degree of entanglement.
When the fibrous web, having a low degree of entanglement of the
fibers therein, is impregnated with an elastic polymer, and the
resultant artificial leather is buffed, the buffed artificial
leather has a paper-like appearance and feel, and a low resiliency,
and is provided with a pile layer having a very low density and a
poor resistance to abrasion. Therefore, the fibrous web mentioned
above is not suitable for producing a nubuck-like artificial
leather. The extemely fine fibers produced by using the melt-blow
method have a diameter of 0.1 to 6.0 microns. The fine fibers may
have a length of about 3 cm or more.
The fibrous web prepared by the method as mentioned above is
superimposed on the surface of a woven or knitted fabric and, if
necessary, another fibrous web is superimposed on the opposite
surface of the woven or knitted fabric. Otherwise the fibrous web
can be formed on a surface of a woven or knitted fabric being
continuously conveyed on the conveyer screen by using the melt-blow
method. In this case, it is necessary to prevent the melt-adhering
of the fibers to each other by spacing the woven or knitted fabric
surface from the orifices a distance of 20 to 60 cm.
In order to three-dimentionally entangle the extremely fine fibers
in the web with each other with a high degree of entanglement and
to firmly bond the non-woven fabric constituent to the woven or
knitted fabric constituent, the precursory sheet is subjected to a
treatment thereof with numerous fluid stream jets having a high
speed. By utilizing this type of treatment, both the constituents
can be firmly bonded togehter substantially without breakage or
deterioration of the extremely fine fibers in the non-woven fabric
constituent and the fibers in the woven or knitted fabric
constituent, and a composite fabric having a high bonding strength
and bulkiness can be obtained.
The conventional needle-punching method in unsuitable for producing
the composite fabric of the present invention, because the
needle-punching operation results in breakage of the extremely fine
fibers and can not cause the entanglement of the extremely fine
fibers with each other. Also, when the fibrous web consisting of
the extremely fine fibers is needle-punched with numerous needles
each having a barb, a number of the extremely fine fibers are
removed by action of the barb with the result that numerous holes
are undesirably formed in the web. Furthermore, the needle-punching
operation causes a portion of the fibers in the woven or knitted
fabric to be broken or to penetrate to the outersurface of the
fibrous web through the body of the fibrous web. The needle-punched
composite fabric has a low mechanical strength, for example,
tensile strength, tear strength and sewing strength. Accordingly,
even if this needle-punched composite fabric is impregnated with
the elastic polymer and, then, the surface of the impregnated
composite fabric is buffed, the resultant artificial leather has a
paper-like appearance and feel, and a low uniformity is quality due
to its poor resiliency, and bonding strength, and a poor density of
the pile layer. Therefore, the needle-punched composite fabric can
not be used as the substratum for a nubuck-like artificial
leather.
The treatment of the precursory sheet with the high speed fluid
stream jets can be carried out by using a method as disclosed in
the Japanese Patent Application No. 48-13749(1973).
Referring to FIG. 6, an apparatus 30 for ejecting numerous fluid
stream jets comprises a screen conveyer 31 which rotates around a
pair of rollers 32 and 33, a pair of rollers 34 and 35 for delivery
a resultant composite fabric 36, and a nozzle device 37 for
ejecting the fluid stream jets. The nozzle device 37 has numerous
orifices 37a through which a fluid is ejected under a high pressure
to form numerous the fluid stream jets. The ejecting orifices are
arranged in at least one row. In the apparatus as indicated in FIG.
6, the ejecting orifices are arranged in three rows and formed on
three distributing pipes 38, 39 and 40. These distributing pipes
38, 39 and 40 are connected to a fluid supply source (which is not
shown in FIG. 6) through a main pipe 41.
In the operation of the apparatus as shown in FIG. 6, the screen
conveyer 31 is rotated in a direction of an arrow A, and a
precursory sheet 42 is placed on the screen 31 in such a manner
that the fibrous web surface of the precursory sheet faces the
orifices 37 and is forwarded on the screen conveyer 31 in the
direction shown by an arrow B. Numerous fluid stream jets are
ejected through the orifices 37 toward the fibrous web surface of
the precursory sheet 42 to convert it into a composite fabric 36.
The ejecting device 37 is reciprocally moved in a direction at a
right angle to the direction in which the precursory sheet 42 is
forwarded so as to uniformly impact the precursory sheet with a
number of the fluid jets ejected under a high pressure. The
precursory sheet 42 is converted into a body of the composite
fabric 36 and, then, the resultant composite fabric is delivered by
the delivery rollers 34 and 35.
In the process for converting the precursory sheet into the
composite fabric, it is preferable that at the same time as the
fluid stream jetting operation, a reduced pressure of 10 to 200
mmHg is applied onto a surface of the precursory sheet opposite to
the fibrous web surface. This pressure reducing operation is
effective to suck the fluid through the body of the precursory
sheet together with numerous air bubbles formed in the inside of
the precursory sheet. The air bubbles existing in the inside of the
presursory sheet obstruct the entanglement of the extremely fine
fibers with each other and with the fibers in the woven or knitted
fabric constituent. However, the air bubbles are very difficult to
remove with suction due to the extremely small size of the air
bubbles which are formed in extremely small spaces formed between
the extremely fine fibers.
The reduced pressure to be applied onto the opposite surface of the
precursory sheet is required to be in a range of from 10 to 200
mmHg, more preferably, 20 to 100 mmHg. An excessively reduced
pressure larger than 200 mmHg tends to restrict the freedom of
movement of the extremely fine fibers in the precursory sheet, and
therefore, to obstruct the entanglement of the extremely fine
fibers with each other and with the fibers in the woven or knitted
fabric constituent.
In the fluid stream ejecting operation, it is preferable that the
fluid jet be formed from water and be in the form of a right
circular rod.
FIG. 7 shows a cross-sectional profile of an orifice usable for the
process of the present invention. In the orifice 50 as shown in
FIG. 7, a cylindrical orifice 51 has an ejecting hole 52. The
diameter of the ejecting hole 52 is preferably in a range of from
0.06 to 0.20 mm, more preferably, 0.07 to 0.15 mm, still more
preferably, 0.08 to 0.12 mm. In order to eject water through the
ejecting hole, it is preferable that the water be under a pressure
of 15 to 100 kg/cm.sup.2, more preferably, 20 to 70 kg/cm.sup.2.
The higher the ejecting pressure of the water, the higher the
bonding strength and the density of the resultant composite fabric.
However, an excessively high ejecting pressure will result in
formation of undesirable holes in and dents on the resultant
composite fabric. The excessively high ejecting pressure also will
result in an excessively high density and stiffness of the
resultant composite fabric. Also, an excessively low ejecting
pressure will result in a poor bonding strength of the non-woven
fabric constituent and the woven or knitted fabric constituent, and
in incomplete conversion of the fibrous web into the non-woven
fabric.
In the fluid stream ejecting operation, it is important that the
fibrous web surface of the precursory sheet be uniformly impacted
with numerous fluid stream jets. For this purpose, it is required
that the fluid jetting operation be carried out at a total impact
area ratio of at least 1.5, the term "total impact area ratio"
referring to a ratio of a total impact area of fluid jets on a
precursory sheet surface to an area of the precursory sheet surface
to be impacted. For example, in the case where a precursory sheet
is forwarded at a constant velocity in one direction, and the
location of the fluid stream jets is reciprocally moved in a
direction at a right angle to the forwarding direction of the
precursory sheet, the total impact area ratio can be calculated in
accordance with the formula (I)
wherein R represent the diameter in cm of an area where the fluid
stream impacts with the fibrous web surface, L represents the
forwarding velocity in cm/min of the precursory sheet, T represents
the number of reciprocal movements per minute of the fluid stream,
n represents the number of fluid streams jetted onto the precursory
sheet, N represent the number of jetting operations applied to the
precursory sheet, A represents the length in cm of one movement of
the fluid stream and W represents the width in cm of the precursory
sheet.
Only when the fluid jetting operation is carried out at a total
impact area ratio of 1.5 or more, can the fibrous web be uniformly
and completely converted into a body of a non-woven fabric
constituent and is the non-woven fabric constituent able to be
uniformly and completely bonded to the woven or knitted fabric
constituent. In the case of a total impact area ratio less than
1.5, it is impossible to obtain a composite fabric having a high
enough bonding strength for producing a practically useful
artificial leather. In view of the necessary degree of density,
bonding strength and entanglement of the extremely fine fibers with
each other of the composite fiber usable for producing the
artificial leather, the fluid jetting operation is preferably
performed at a total impact area ratio of 2.0 to 50, more
preferably, 3.0 to 10. An extremely large total impact area ratio,
for example, more than 50, will results in an excessively high
density of the resultant composite fabric. Such an excessively high
density will cause the resultant artificial leather to have an
excessively high stiffness. Further, it should be noted that an
excessively large total impact area ratio, for example, of more
than 50, will be unable to contribute to the increase of the
bonding strength of the resulting composite fabric.
In the above-described ejecting process, the high speed fluid
stream jets may directly impact on the fibrous web surface of the
precursory sheet. Otherwise, a metal net may be located between the
ejecting orifices and the fibrous web surface so as to weaken the
impacting force of the fluid stream jets and divide then into a
plurality of thin streams by contact of the fluid stream jets with
the net. The reciprocal movement of the fluid stream jets may be
carried out along either a straight line or a curve. Otherwise, a
rotational movement may be added to the reciprocal movement of the
fluid stream jets.
The ejecting operation may be carried out one or more times for one
precursory sheet. However, it is preferable that the at least two
ejecting operations be applied to one precursory sheet. That is, it
is preferable that a first ejecting operation be applied to one
precursory sheet so as to strongly impact against it, and, then, a
later ejecting operation or operations be applied to the precursory
sheet so as to weakly impact against it. The first strong impact
operation results in formation of holes and dents on the surface of
the fibrous web and, therefore, in formation of a rough surface of
the resultant composite fabric. When such a composite fabric is
converted into an artificial leather and buffed, the rough surface
results in an uneven pile layer. Accordingly, it is preferable to
eliminate the holes and dents formed in the first ejecting
operation by the later ejecting operation or operations. That is,
the later ejecting operation is effective for obtaining a
nubuck-like artificial leather having an even pile surface, and a
high and uniform density.
For the purpose of the eliminating the holes and dents formed by
action of the fluid stream jets in a proceeding jetting step, it is
preferable that each fluid stream jet in a preceding jetting step
impact against the precursory sheet in an impact area smaller than
that in a succeeding step and the impacting force of each fluid
stream jets in a preceding jetting step be at least ten times that
in a succeeding step. That is, the impact area in a second or later
jetting step is preferably in a range of from 3.0 to 5.0
mm.sup.2.
The term "impact area", used herein, refers to a cross-sectional
area of one fluid stream jet in which the fluid stream jet impacts
against the precursory sheet surface. The impact area can be
determined by using either of the following methods. In the case
where a fluid stream jet is in the form of a cone, the impact area
is calculated from the distance between the ejecting orifice and
the precursory sheet surface, and an angle between the axis of the
cone and the normal line of the cone. In the other method, a
photograph of the impact area is taken, and the impact area is
measured on the photographic print.
The term "impacting force", used herein, refers to a force applied
by one fluid stram jetted onto the precursory sheet surface and can
be determined in accordance with the equation (2)
wherein F represents an impacting force, P represents a pressure in
kg/cm.sup.2 under which a fluid is ejected through an orifice, S
represents a cross-sectional area in cm.sup.2 of an ejecting hole
of the orifice, A represents an impact area in cm.sup.2 and k is a
constant.
In the jetting process, it is preferable that the ratio of the
impacting force of each fluid stream jet in a preceding jetting
step to that in a succeeding jetting step be at least ten, and more
preferably, that the impacting force satisfys the following
equation (3)
wherein F.sub.1 represents the impacting force of one fluid stream
jet in a preceding step and F.sub.2 represents the impacting force
of one fluid stream jet in a succeeding step.
If the above-mentioned ratio is smaller than 1/500, the holes and
dents formed in a preceding jetting step sometimes can not be
completely eliminated by a succeeding jetting step. Also, if the
above-mentioned ratio is larger than 1/10, the succeeding jetting
step sometimes results in formation of holes and dents on the
precursory sheet, while the holes and dents formed in the preceding
jetting step are eliminated by the succeeding jetting step.
The succeeding jetting step may utilize the same nozzle device as
indicated in FIG. 7 or another type of a nozzle device, for
example, a spraying device. However, it is necessary that the
jetting operation is succeeding step be uniformly applied onto the
precursory sheet.
The composite fabric of the present invention can be converted into
an artificial leather by using any of the conventional methods. For
example, the method disclosed in Japanese Patent Application
Publication No. 37-2489(1962) can be utilized for producing an
artificial leather from the composite fabric of the present
invention. In order to obtain an artificial leather having a high
resiliency and softness, it is preferable that the composite fabric
be impregnated with 20 to 70%, more preferably, 25 to 45%, of a
rubber-like elastic polymer based on the weight of the composite
fabric. The elastic polymer may be selected from polyurethane,
synthetic rubbers such as butadiene-acrylonitrile rubber and
butadiene-styrene rubber, elastic polyvinyl chlorides, elastic
acrylic polymers, polyaminoacids, and elastic copolymers of two or
more monomers of the above-mentioned polymers.
Also, it is preferable that after the composite fabric is
impregnated with the rubber-like elastic polymer, the impregnated
composite fabric be shrunk at an area shrinkage of 5 to 20%, more
preferably, 7 to 15%. The area shrinking process is effective for
increasing the density and resiliency of the resultant artificial
leather and the density of the pile layer. Therefore, even in the
case where the piles are sheared to form a very thin pile layer,
the surface of the resultant artificial leather can be uniformly
covered by a dense pile layer consisting of extremely fine fibers
and no rubber-like elastic polymer appears on the surface of the
artificial leather. A good quality of a nubuck-like artificial
leather can be obtained from the composite fabric of the present
invention.
The artificial leather produced from the composite fabric of the
present invention may be raised by using any conventional raising
machine, for example, a card clothing raising machine and a
so-called sander. In the card clothing raising machine, a card
clothing in which numerous fine needles stand at a high density on
a thin rubber sheet, is wound on a rotatable drum. In the raising
operation, the drum is rotated at a high speed in such a manner
than the top ends of the needles are brought into contact with the
surface of the artificial leather to be raised so as to convert the
individual fine fibers located in the surface portion of the
artificial leather into piles.
The sander involves a drum sander in which sand paper is wound on a
rotatable drum of a belt sander in which an endless belt consisting
of a sand paper is rotated. In both types of sanders, the sand
paper is brought into contact with the surface of the artificial
leather to raise the surface.
The card clothing raising machine is suitable to form relatively
long piles and the sander is proper to produce relatively short
piles. Accordingly, the raising machine suitable for obtaining a
nubuck-like artificial leather is the sander rather than the card
clothing raising machine. However, the artificial leather may be
raised by concurrently using the sander and the card clothing
raising machine. Further, the raised artificial leather may be
subjected to a brushing or shearing process to improve the quality
of the raised pile surface of the artificial leather.
The surface of the artificial leather may also be coated with a
thin layer of a polyurethane. In this case, a grain side layer is
formed on the artificial leather.
The composite fabric of the present invention, and the artificial
leather produced from the composite fabric can be dyed or printed
using a conventional method. Further, the artificial leather may be
subjected to a crumpling process to make the artificial leather
softer.
The composite fabric of the present invention also has an advantage
in that the composite fabric is useful for producing a relatively
thin artificial leather which is useful as a material for clothing,
due to a high mechanical strength, softness and draping property.
Also, the composite fabric of the present invention has a high
compressibility and recovery from compression, because of
incorporation of at least one non-woven fabric constituent which is
bulky and has a high compressibility, and recovery from
compression, into a woven or knitted fabric constituent.
In a conventional process, a thin non-woven fabric is produced by
slicing a thick non-woven fabric into two or more pieces. However,
the process of the present invention can produce a very thin
composite fabric having a thickness of less than 1.0 mm,
particularly, less than 0.5 mm, by forming a thin fibrous web
directly on a thin woven or knitted fabric and, then, converting
the fibrous web into a non-woven fabric while bonding the non-woven
fabric to the woven or knitted fabric.
The composite fabric of the present invention has a smooth and even
surface. Accordingly, the artificial leather obtained from the
composite fabric of the present invention also has a smooth and
even surface, which is able to be uniformly dyed or printed and
converted into a uniform pile layer having a high density.
Also, it is important that the artificial leather obtained from the
composite fabric of the present invention has a good chalk
mark-forming property even when the piles in the pile layer have a
relatively small length of 0.05 to 0.5 mm. This feature of the
artificial leather is similar to that of natural nubuck
leather.
The features and advantages of the present invention are further
illustrated by the examples set forth hereinafter, which are not
intended to limit the scope of the present invention in any
way.
In the following examples and comparison examples, the properties
of the composite fabric and the artificial leather were
respectively determined in accordance with the following
methods.
1. Tensile strength and breaking elongation.
Test specimens, each having a length of 20 cm and a width of 1 cm,
were taken from the fabric to be tested. The full width of the end
portions, of 5 cm lengths, of the specimen was gripped, and the
specimen was stretched with an autograph until the specimen was
broken. The maximum breaking load in kg/mm.sup.2 and the elongation
in % at break was measured.
2. Tear strength.
Test specimens, each having a length of 10 cm and a width of 2 cm,
as indicated in FIG. 8A, were taken from the fabric to be tested.
The specimen was cut from an end thereof to a point C in FIG. 9A.
The end portions A and B, of 5 cm lengths, of the specimen were
gripped and stretched with an autograph, in the manner as shown by
arrows in FIG. 9B, until the specimen was broken. The maximum load
in kg at break was measured.
3. Sewing strength.
Test specimens, having a length of 10 cm and a width of 2 cm, were
taken from the fabric to be tested. Two pieces of the specimens
were overlapped and sewed together, in the manner indicated in FIG.
10, with a sewing machine, using a polyester sewing yarn of 50
metric count and a sewing needle of 11 number count, at a stitch
number of 12 stitches/3 cm. The full width to the end portions, of
5 cm lengths, of the sewed specimens was gripped and stretched with
an autograph until the sewed portion was broken. The maximum
breaking load in kg/cm was measured.
4. Recovery on elongation.
Test specimens, 20 cm long and 1 cm wide, were taken from the
fabric to be tested. A top end portion, of 5 cm length, of the
specimen was gripped and fixed at its full width. The lower end
portion, of 5 cm length, of the specimen was gripped and loaded
with a weight of 1.0 kg. After the specimen was kept under the
loaded condition for 10 minutes, the length of the specimen was
measured. The specimen was released from the load and kept in the
non-loaded condition for 10 minutes. After that, the length of the
specimen was again measured. The recovery on elongation was
determined in accordance with the following equality:
wherein L.sub.0 is the original length of the specimen before
loading, L.sub.1 is the length of the specimen after loading, and
L.sub.2 is the length of the specimen after releasing the load.
5. Compressibility and recovery on compression
Test specimens, 10 cm long and 10 cm wide, were taken from the
fabric to be tested. Ten pieces of the specimens were superimposed
and a thin metal plate having the same size as the specimen and a
weight of 50 g was placed on the superimposed specimens. The total
thickness (t.sub.0) of the superimposed specimens was measured. A
weight of 10 kg was placed on the metal plate in such a manner that
the superimposed specimens were uniformly compressed. The specimens
were kept in the compressed condition for 30 minutes. Thereafter,
the total thickness (t.sub.1) of the compressed superimposed
specimens was measured. The weight was removed and the superimposed
specimens were kept in the non-weighted condition for 30 minutes.
Thereafter, the total thickness (t.sub.2) of the superimposed
specimens was againmeasured.
The compressibility and the recovery on compression were determined
in accordance with the following equalities.
6. Density of fabric
In the determination of density of fabric, a MAEDA type of
compressive elasticity tester was used. A test specimen, 6 cm wide
and 7 cm long, was placed on a disc having a diameter of 2.0 cm,
and a weight of 5.0 g was placed on the testing specimen at a load
of 1.6 g/cm.sup.2. Under this condition, the thickness of the
specimen was measured. The volume in cm.sup.3 of the specimen was
calculated by using the thickness measured above, and the weight of
g of the specimen was measured. The density of the specimen was
determined in accordance with the following equality.
7. Bonding strength
A test specimen, 20 cm long and 1 cm wide, was taken from the
composite fabric to be tested. An end portion of the specimen was
split from an end thereof to a point D 10 cm far from the end along
the intersurface between a non-woven fabric constituent and a woven
or knitted fabric constituent, in the manner as indicated in FIG.
8. The end portions E and F, of 5 cm lengths, of the specimen were
gripped and stretched in opposite directions to each other with an
autograph in the manner as indicated in FIG. 8, until the specimen
was broken. The maximum load in g/cm was measured.
8. Resistance to abrasion
Test specimens, 200 mm long and 50 mm wide, were taken from the
fabric to be tested. The specimens were set on a CASTOM type flat
abrasion tester. The abrasion test was carried out by abrading the
specimen 1,000 times with sand paper of a count of AA400, under a
load of 456 g, at a rate of 125 cycles/minute. After completion of
the abrasion test, the abrasion resistance of the specimen was
evaluated in accordance with the following standard.
______________________________________ Class Remarks
______________________________________ 5 No change 4 A minor
portion of surface layer is broken 3 A major portion of surface
layer is broken 2 The inside layer is broken 1 A hole is made
______________________________________
9. Softness
Softness was measured in accordance with the method set forth in
ASTM D 1388-64.
EXAMPLE 1
Polyethylene terephthalate chips were melted in an extruder and
extruded at a temperature of 320.degree. C. through 1500 spinning
orifices each having a diameter of 0.30 mm, at a extruding rate of
0.15 g/minute per orifice, into a stream of steam blown in the same
direction as the extruding direction, at a temperature of
365.degree. C., under a pressure of 3.5 kg/cm.sup.2. The resultant
discontinuous and extremely fine fivers were randomly accumulated
on a screen conveyer moving at a constant velocity along a path 40
cm far from the orifice ends. A random fibrous web having a weight
of 80 g/cm.sup.2 was obtained. Based on electron microscopic
observation, the resultant fibers had an extremely small diameter
of 1.5 microns, which corresponds to a denier of about 0.02, and
substantially no melt-adhering of the fibers to each other was
found.
A rough interlock knitted fabric made of polyethylene terephthalate
multifilament yarn of 40 denier/36 filaments was uniformly opened
and placed on the above-prepared random web. Another random web
prepared as mentioned above was placed on the knitted fabric to
provide a three layer precursory sheet. The precursory sheet was
converted into a composite fabric by using the apparatus as shown
in FIG. 6. That is, the precursory sheet was placed on the screen
conveyer rotating around a pair of rollers at a velocity of 10
m/minute. Numerous water streams were ejected from the orifices
toward a random web surface of the precursory sheet under the
following conditions.
______________________________________ Diameter of orifice hole
0.10 mm Number of orifices 420 Number of reciprocal movements of
orifices 200/minutes Length of one movement of orifice 3.0 cm
Jetting pressure of water 25 kg/cm.sup.2 Forwarding velocity of
precursory sheet 1.0 m/minute Width of precursory sheet 30 cm
Impact area per jet 0.071 mm.sup.2 Total impact area ratio 5.0
Distance between orifice and precursory sheet 3.0 cm
______________________________________
Simultaneously with jetting operation, a reduced pressure of 50
mmHg was applied to the opposite surface of the precursory sheet.
The above-mentioned operations were applied to both the random web
surfaces of the precursory sheet.
Next, both surfaces of the above-treated precursory sheet were
impacted with numerous water jets under the following conditions,
while a reduced pressure of 35 mmHg was applied to the surface
opposite to the surface onto which the water jets were ejected.
______________________________________ Diameter of orifice hole
0.10 mm Number or orifices 420 Number of reciprocal movements of
orifices 100/minute Jetting pressure of water 50 kg/cm.sup.2
Forwarding velocity of precursory sheet 2.0 m/minute Impact area
per jet 7.1 mm.sup.2 Distance between orifice and precursory sheet
20 cm ______________________________________
The ratio of the impact force of the water jet in the first jetting
step to that in the second step was 1/50.
The resultant composite fabric had a cross-sectional structure as
indicated in FIG. 3, and a high softness and resiliency. Both of
the surfaces of the composite fabric contained no holes or dents
and were very smooth and even.
The properties of the composite fabric are indicated below.
______________________________________ Weight 200 g/m.sup.2
Thickness 0.78 mm Density 0.25 g/cm.sup.3 Tensile strength 0.95
kg/mm.sup.2 Tear strength 3.3 kg Sewing strength 6.7 kg/cm Recovery
on elongation 83% Compressibility 32% Recovery on compression 81%
Softness 26 mm Bonding strength 70 g/cm Ratio of total weight of
non-woven fabric constituents to knitted fabric constituent
______________________________________
The non-woven fabric constituents in the composite fabric had a
density of 0.23 g/cm.sup.3 and a tensile strength of 0.21
kg/mm.sup.2.
The composite fabric was impregnated with a 5% aqueous solution of
polyvinyl alcohol and dried. Thereafter, the composite fabric was
impregnated with 40%, based on the weight of the composite fabric,
of a 10% solution of polyurethane elastomer in dimethyl formamide.
The impregnated composite fabric was immersed in a 30% aqueous
solution of dimethyl formamide so as to completely coagulate the
polyurethane elastomer in the composite fabric. Next, the composite
fabric was immersed in hot water at a temperature of 70.degree. C.
so as to allow the composite fabric to shrink at an area shrinkage
of 10%. The resultant artificial leather was washed, dried and,
then, buffed on one surface thereof with sand paper. The resultant
artificial leather had a nubuck-like pile layer consisting of
extremely fine fibers and having a uniform and high density. The
nubuck-like artificial leather had a high softness and resiliency.
The pile layer surface was observed by using a microscope. The pile
layer was composed of extremely fine non-bundled fibers having an
average diameter of about 1.5 microns and a length of 50 to 500
microns. In spite of the extremely small length of the piles, the
pile layer of the artificial leather had an excellent chalk
mark-forming property and no polyurethane elastomer appeared on the
pile layer surface.
The properties of the nubuck-like artificial leather are indicated
below.
______________________________________ Weight 285 g/m.sup.2 Density
0.32 g/cm.sup.3 Tensile strength 1.03 kg/mm.sup.2 Tear strength 3.5
kg Sewing strength 7.0 kg/cm Recovery on elongation 90%
Compressibility 25% Recovery on compression 86% Bonding strength
230 g/cm Softness 32 mm Resistance to abrasion class 5
______________________________________
COMPARATIVE EXAMPLE 1
Island-in-sea type composite filaments were produced from 40% by
weight of nylon 6 as an island component polymer and 60% by weight
of polystyrene as a sea component polymer by means of a
melt-spinning process. The composite filaments were crimped by
using a stuffing box type crimping machine, and cut to form staple
fibers having a length of 35 mm. The staple fibers were converted
into a cross-laid web. The web was needle-punched at a needling
density of 500 punches/cm.sup.2 to form a non-woven fabric having a
weight of 200 g/m.sup.2. The non-woven fabric was treated with
chloroform to eliminate the sea component polymer. The composite
staple fibers were converted into fibrous bundles each composed of
100 individual extremely fine fibers, each having a denier of
0.1.
The resultant non-woven fabric had the following properties.
______________________________________ Weight 280 g/m.sup.2 Density
0.13 g/cm.sup.3 Tensile strength 0.38 kg/mm.sup.2 Tear strength 1.5
kg Sewing strength 1.8 kg Recovery on elongation 40%
Compressibility 52% Recovery on compression 54% Softness 38 mm
______________________________________
The non-woven fabric was impregnated with the same polyurethane
elastomer and by the same method as those described in Example 1.
The resultant artificial leather was buffed to form a pile layer.
The resultant buffed artificial leather had a poor resiliency and a
paper-like appearance and feel. The pile layer was composed of
fibrous bundles at a low density. Accordingly, the pile layer had a
poor chalk mark-forming property and a rough surface. Further, the
artificial leather had a touch and appearance similar to a low
grade of suede leather.
COMPARATIVE EXAMPLE 2
A cross-laid web was produced by using a carding engine and a
cross-layer from 9 parts by weight of polethylene terephthalate
staple fibers, each having a denier of 0.5, which corresponds to a
diameter of about 7 microns, and a shrinkage of 70%, and 1 part by
weight of crimped polyethyelne terephthalate staple fibers having a
denier of 1.5. The web was needle-punched at a punching density of
500 punches/cm.sup.2, to produce a non-woven fabric having a weight
of 200 g/m.sup.2. The non-woven fabric was immersed in hot water of
80.degree. C. so as to allow the fabric to shrink at an area
shrinkage of about 50%. The shrunk non-woven fabric had the
following properties.
______________________________________ Weight 280 g/cm.sup.2
Density 0.15 g/cm.sup.3 Tensile strength 0.42 kg/mm.sup.2 Tear
strength 1.8 kg Sewing strength 2.0 kg/cm Recovery on elongation
56% Compressibility 47% Recovery on compression 62% Softness 47 mm
______________________________________
That is, the non-woven fabric had a poor density, resiliency,
mechanical strength and softness.
The non-woven fabric was impregnated with the same polyurethane
elastomer and in the same manner as those described in Example 1.
The resultant artificial leather was buffed with sand paper. The
resultant pile layer was composed of a mixture of polyethylene
terephthalate fibers having deniers of 1.5 and 0.5, and had a low
density, and an uneven and rough surface. The surface had a sandy
feel. When the piles were cut into a length of 1 mm or less, the
pile layer had a poor chalk mark-forming property and did not
resemble the pile layer of a nubuck leather.
EXAMPLES 2 THROUGH 7 AND COMPARATIVE EXAMPLES 3
In each of Examples 2 through 5, a random web having a weight of
100 g/m.sup.2 was produced from fibers having a diameter as
indicated in Table 1. The fibers were produced by melting nylon 6
in an extruder and extruding the melt at a temperature of
320.degree. C., at a extruding rate as indicated in Table 1, into a
stream of steam, at a temperature of 360.degree. C. ejected under a
pressure of 4.0 kg/cm.sup.2.
In each of Examples 6 and 7, nylon 6 was melted in an extruder, the
melt was extruded at a temperature of 295.degree. C., at a
extruding rate as indicated in Table 2, and the extruded melt
streams were solidified and wound up at a speed of 800 m/minute.
The filaments prepared were drawn at a draw ratio of 2.7 to provide
nylon 6 filaments each having a denier as indicated in Table 1.
In Comparative Example 3, the same procedures as those described in
Examples 6 and 7 were carried out, except that the extruding rate
and denier of the resultant drawn filaments were as indicated in
Table 1.
In each of Examples 6 and 7 and Comparative Example 3, the drawn
filaments were cut to form staple fibers 5 mm long. The staple
fibers were suspended in water in an amount of 2000 times the
weight of the staple fibers. A dispersing agent consisting of
polyacrylamide was added in a concentration of 0.01% by weight to
the suspension. The suspension was stirred so as to uniformly
distribute the staple fibers in the water. The suspension was
subjected to a paper-making process using a hydroformer type
paper-making machine, to produce a random web having a weight of
100 g/m.sup.2.
In each of Examples 2 through 7 and Comparative Example 3, a tricot
fabric consisting of nylon 6 multifilament yarn, of 70 denier/36
filaments and having a weight of 60 g/m.sup.2, was interposed
between two pieces of the random webs obtained as described above
to provide a three layer precursory sheet. The precursory sheet was
converted into a composite fabric by using the same water-jetting
process as that used in Example 1. The composite fabric was
converted into a buffed artificial leather by using the same
process as that employed in Example 1. The properties of the
resultant artificial leathers of Examples 2 through 7 and
Comparative Example 3 are indicated in Table 1.
TABLE 1
__________________________________________________________________________
Property of artificial leather Extruding Average Resistance rate
diameter to g/min per of fiber Appearance Softness abrasion
Synthetic orifice (micron) (*) (mm) (class) estimation
__________________________________________________________________________
Example No. 2 0.10 0.1 good 26 3 good nubuck-like 3 0.12 0.5 good
26 4 very good nubuck-like 4 0.15 1 very good 28 5 excellent high
grade nubuck-like 5 0.20 2 very good 30 5 excellent high grade
nubuck-like 6 0.05 4 good 35 5 very good nubuck-like 7 0.07 6 good
38 5 good nubuck-like Comparative Example No. 3 0.10 8 bad not like
49 5 bad nubuck
__________________________________________________________________________
Note (*)Appearance involves chalk markforming property and density
of piles
Table 1 shows that the artificial leathers produced by using fibers
having a diameter larger than 6 microns had a poor chalk
mark-forming jproperty and a low density of piles. This type of
artificial leather also had an undesirable sandy feel and,
therefore, did not resemble natural nubuck leather. The fibers
having a diameter of from 0.1 to 6.0 microns were useful for
providing an artificial leather having a natural nubuck
leather-like appearance and feel. Especially, the fibers of 1 to 2
micron diameter were useful for producing an artificial leather
having a high grade of natural nubuck leather-like appearance and
feel, and a very high softness and a high resistance to
abrasion.
EXAMPLE 8
Polyethylene terephthalate chips were melted in an extruder and
extruded at a temperature of 320.degree. C., through 1500 spinning
orifices, each having a diameter of 0.30 mm, at a extruding rate of
0.25 g/minute per orifice, into a stream of steam blown in the same
direction as the extruding direction, at a temperature of
395.degree. C. under a pressure of 2.5 kg/cm.sup.2. The resultant
extremely fine fibers were accumulated on a screen conveyer moving
at a constant velocity and spaced 50 cm from the orifices. The
resultant random fibrous web had a weight of 80 g/m.sup.2 and
consisted of numerous extremely fine fibers with an average
diameter of 3 microns. A two layer precursory sheet was prepared by
superimposing the above-prepared random web on a tricot fabric
consisting nylon 6 multi-filament yarms of 150 denier/50 filaments
and having a weight of 80 g/m.sup.2. The precursory sheet was fed
onto the screen conveyer of the water-jetting apparatus as
indicated in FIG. 6 in such a manner that the random web surface of
the precursory sheet faced the orifices. The water jetting
operation was applied to the precursory sheet under the following
conditions.
______________________________________ Diameter of orifice hole
0.20 mm Number of orifices 420 Number of reciprocal movements of
orifices 150/minutes Length of one movement of orifices 3.0 cm
Jetting pressure of water 50 kg/cm.sup.2 Forwarding velocity of
precursory sheet 2.0 m/minute Width of precursory sheet 30 cm
Impact area per jet 0.50 mm.sup.2 Total impact area ratio 13.4
Distance between orifice and precursory sheet 4 cm
______________________________________
Simultaneously with the jetting operation, a reduced pressure of
150 mmHg was applied to the opposite surface of the precursory
sheet. The above-mentioned operations were repeated two times. The
resultant composite fabric had an internal structure as indicated
in FIG. 4, and was highly soft and resilient.
The composite fabric had the following properties.
______________________________________ Weight 160 g/m.sup.2
Thickness 0.50 mm Density 0.32 g/cm.sup.3 Tensile strength 1.4
kg/mm.sup.2 Tear strength 4.2 kg Sewing strength 6.8 kg/cm Recovery
on elongation 82% Compressibility 28% Recovery on compression 78%
Softness 31 mm Bonding strength 220 g/cm Ratio of weight of
non-woven fabric 1.0 constituent to tricot fabric constituent
______________________________________
The non-woven fabric constituent in the composite fabric had a
density of 0.26 g/cm.sup.3 and a tensile strength of 0.30
kg/mm.sup.2.
The composite fabric was impregnated with 70%, based on the weight
of the composite fabric, of the same polyurethane elastomer and by
the same method as those used in Example 1. The impregnated fabric
was shrunk in boiling water at an area shrinkage of 7% and, then,
buffed with sand paper, to provide a nubuck-like artificial
leather.
The pile layer formed on the artificial leather surface was
composed of extremely fine piles with a length of 200 microns and
had an even appearance. The pile layer also had a high density and
a good chalk mark-forming property.
The resultant nubuck-like artificial leather had the following
properties.
______________________________________ Weight 180 g/cm.sup.2
Thickness 0.4 mm Density 0.45 g/cm.sup.3 Tensile strength 1.6
kg/mm.sup.2 Tear strength 4.4 kg Sewing strength 7.2 kg/cm Recovery
on elongation 86% Compressibility 24% Recovery on compression 84%
Softness 42 mm Bonding strength 360 g/cm Resistance to abrasion
class 5 ______________________________________
EXAMPLES 9A THROUGH 9D
In each of Examples 9A through 9D, two pieces of the same random
webs as that used in Example 1 were prepared. A type of woven or
knitted fabric as indicated in Table 2 was interposed between two
pieces of the random webs to prepare a three layer precursory
sheet. The precursory sheet was subjected to a first water jetting
process by using an apparatus as indicated in FIG. 6 under the
following conditions.
______________________________________ Diameter of orifice hole
0.15 mm Number of orifices 420 Number of reciprocal movements of
orifices 200/minutes Length of one movement of orifice 3.0 cm
Jetting pressure 40 kg/cm.sup.2 Forwarding velocity of precursory
sheet 1.7 m/minute Width of precursory sheet 30 cm Impact area per
jet 0.20 mm.sup.2 Total impact area ratio 9.9 Distance between
orifice and precursory sheet 3.5 cm
______________________________________
A reduced pressure of 70 mmHg was applied onto the opposite surface
of the precursory sheet during the water-jetting operation.
The above-mentioned operations were carried out twice on each of
the web surfaces of the precursory sheet.
Next, the above-treated sheet was subjected to a second
water-jetting process by using an apparatus as shown in FIG. 6
under the following conditions.
______________________________________ Diameter of orifice 0.10 mm
Number of orifices 400 Number of reciprocal movements of orifices
120/minute Jetting pressure 100 kg/cm.sup.2 Forwarding velocity of
sheet 1.5 m/minute Impact area per jet 3.6 mm.sup.2 Distance of
orifice to sheet 1.8 cm Ratio of impact force of water jet in
second 1/16 step to that in first step
______________________________________
The resultant composite fabric was highly soft smooth and resilient
and had the properties as shown in Table 2.
TABLE 2
__________________________________________________________________________
Example No. 9A 9B 9C 9D Woven or Type Knitted.sup.1 Woven.sup.2
Double.sup.3 Tricot.sup.4 knitted Weight lace fabric gauze knitted
fabric fabric fabric (g/m.sup.2) 20 30 80 100
__________________________________________________________________________
Composite Weight (g/m.sup.2) 180 190 240 260 fabric Thickness (mm)
0.75 0.68 0.80 0.95 Density (g/cm.sup.3) 0.24 0.28 0.30 0.27
Tensile strength (kg/mm.sup.2) 0.6 0.8 1.2 1.5 Tear strength (kg)
6.4 7.6 8.8 10.5 Sewing strength (kg/cm) 6.6 7.5 11.5 12.4 Softness
(mm) 26 30 33 38 Recovery on elongation (%) 81 87 90 93
Compressibility (%) 32 38 42 46 Recovery on compression (%) 80 86
92 84 Bonding strength (g/cm) 160 85 55 35
__________________________________________________________________________
Note .sup.1 Knitted lace fabric consisted of polyethylene
terephthalate multifilament yarns of 20 denier/15 filaments. .sup.2
Woven gauze was composed of viscose rayon multifilament yarns of 4
denier/30 filaments. .sup.3 Double knitted fabric was composed of
nylon 66 multifilament yarns of 70 denier/24 filaments. .sup. 4
Tricot fabric was composed of nylon 66 multifilaments yarns of 50
denier/10 filaments.
The composite fabric of Example 9B was impregnated with 50%, based
on the weight of the composite fabric, of styrene-butadiene rubber
by using a styrene-butadiene rubber latex. The impregnated fabric
was immersed in boiling water so as to allow the fabric to shrink
at an area shrinkage of 20%. The resultant artificial leather was
buffed with sand paper. The resultant nubuck-like pile layer was
composed of extremely fine piles having an average length of 800
micron, and had a high density and a good chalk mark-forming
property. The nubuck-like artificial leather had a weight of 290
g/m.sup.2 and a density of 0.35 g/cm.sup.3.
EXAMPLE 10
Nylon 66 chips were melted in an extruder and extruded at a
temperature of 355.degree. C., at an extruding rate of 0.15
g/minute per orifice, into an air stream blown at a temperature of
410.degree. C. under a pressure of 3.5 kg/cm.sup.2. The resultant
extremely fine fibers, having an average diameter of 3 microns were
accumulated on a net moving at a constant velocity and spaced 30 cm
from the orifice. A random web having a weight of 40 g/m.sup.2 was
obtained.
The same procedures as those mentioned above were carried out,
except that the velocity of movement of the net was one third of
that in the above-mentioned procedures. A random web having a
weight of 120 g/m.sup.2 was obtained.
A plain woven fabric consisting of polyethylene terephthalate
multifilament yarns, of 40 denier/200 filaments, and having a
weight of 60 g/m.sup.2, was interposed between the 40 g/m.sup.3
random web and the 120 g/m.sup.3 random web prepared as described
above. The resulting three layer precursory sheet was subjected to
a water jetting process by using an apparatus as shown in FIG.
6.
The water jetting operation was carried out under conditions
detailed below, while a reduced pressure of 200 mmHg was applied
onto the lower surface of the precursory sheet.
______________________________________ Diameter of orifice 0.06 mm
Number of orifices 420 Number of reciprocal movement of orifices
200/minute Length of one movement of orifices 3.0 cm Jetting
pressure 60 kg/cm.sup.2 Forwarding velocity of sheet 1.0 m/minute
Width of sheet 30 cm Impact area per jet 0.032 mm.sup.2 Total
impact area ratio 3.4 Distance between orifice and sheet surface
3.5 cm ______________________________________
The above-mentioned operations were applied to both the upper and
lower surfaces of the procursory sheet.
The resultant composite fabric had the following properties.
______________________________________ Weight 200 g/m.sup.3
Thickness 1.1 mm Density 0.18 g/cm.sup.3 Tensile strength 0.87
kg/mm.sup.2 Tear strength 3.1 kg Sewing strength 6.4 kg/cm
Compressibility 34% Recovery on compression 78% Recovery on
elongation 80% Softness 28 mm Bonding properties 60 g/cm Ratio of
total weight of non-woven fabric 2.7 constituent to woven or
knitted fabric constituent
______________________________________
The non-woven fabric constituent had a density of 0.18 g/cm.sup.3
and a tensile strength of 0.23 kg/mm.sup.2. The composite fabric
was impregnated with 20%, based on the weight of the composite
fabric, of the same polyurethane elastoner and by the same method
as those used in Example 1, immersed in boiling water so as to
shrink it at an area shrinkage of 12%, and then, buffed with sand
paper. The resultant nubuck-like artificial leather had a smooth
and even pile layer consisting of extremely fine piles having an
average length of 1 mm. The pile layer had a high density and a
good chalk mark-forming property. The artifical leather was of a
weight of 210 g/m.sup.2 and a density of 0.25 g/cm.sup.3.
EXAMPLE 11
A random web having a weight of 150 g/m.sup.2 and composed of
extremely fine polyethylene terephthalate fibers, having an average
diameter of 1.5 microns, was prepared by the same method as used in
Example 1, except that the extremely fine fibers were blown toward
a woven fabric placed on the net moving at a constant velocity. The
woven fabric was composed of nylon 66 multifilament yarns of 120
deniers/86 filaments and had a weight of 80 g/m.sup.2. The distance
between the orifice and the net was 40 cm.
The resultant two layer precursory sheet was subjected to a
water-jetting process by using an apparatus as shown in FIG. 6
under the conditions indicated below, while a reduced pressure of
40 mmHg was applied to the lower surface of the precursory
sheet.
______________________________________ Diameter of orifice 0.10 mm
Number of orifices 360 Number of reciprocal movements of orifices
50/minutes Length of one movement of orifices 3.0 cm Jetting
pressure 30 kg/cm.sup.2 Forwarding velocity of sheet 2.0 m/minute
width of sheet 30 cm Impact area per jet 0.071 mm.sup.2 Total
impact area ratio 1.6 Distance between orifice and sheet 3.0 cm
______________________________________
The above-mentioned operations were repeated three times to convert
the precursory sheet into a composite fabric.
The resultant composite fabric was highly soft and resilient and
had the following properties.
______________________________________ Weight 220 g/m.sup.2
Thickness 1.5 mm Density 0.15 g/cm.sup.3 Tensile strength 1.1
kg/mm.sup.2 Tear strength 2.9 kg Sewing strength 6.0 kg/cm Recovery
on elongation 78% Compressibility 33% Recovery on compression 75%
Softness 26 mm Bonding strength 30 g/cm Ratio in weight of
non-woven 1.9 fabric constituent to woven fabric
______________________________________
The non-woven fabric constituent had a density of 0.12 g/cm.sup.3
and a tensile strength of 0.27 kg/mm.sup.2.
The resultant composite fabric was impregnated with 40%, based on
the weight of the composite fabric, of the same polyurethane
elastomer and by the same method as those used in Example 1, and
then, the surface of the non-woven fabric constituent was buffed
with sand paper.
The resultant nubuck-like artificial leather had a uniform and
dense pile layer consisting of extremely fine piles. The artificial
leather also had the following properties.
______________________________________ Weight 320 g/m.sup.2 Density
0.25 g/cm.sup.3 Tensile strength 1.3 kg/mm.sup.2 Tear strength 3.2
kg Sewing strength 6.5 kg/cm Recovery on elongation 86%
Compressibility 31% Recovery on compression 81% Softness 33 nm
Resistance to abrasion class 5 Bonding strength 210 g/cm
______________________________________
EXAMPLE 12
Viscose rayon yarns, each consisting of 50 individual filaments,
each having a diameter of 5 microns, were cut to provide staple
fibers having a length of 3 mm. 650 g of the staple fibers were
suspended in 500 liters of water containing 0.0002% by weight of a
dispersing agent consisting of polyacrylamide, to provide an
aqueous suspension containing 0.13% by weight of the staple
fibers.
Two pieces of random webs, having a weight of 80 g/m.sup.2, were
prepared from the aqueous suspension by using a hydroformer type
paper-making machine.
A twill woven fabric, which was composed of cuprammonium rayon
multifilaments yarns of 40 deniers/46 filaments and had a weight of
80 g/m.sup.2, was interposed between the two pieces of the random
webs, prepared as mentioned above, to provide a three layer
precursory sheet.
The same water-jetting process as that used in Example 1 was
applied to each random web surface of the precursory sheet while a
reduced pressure of 10 mmHg was applied to the opposite surface of
the precursory sheet.
The resultant composite fabric had a density of 0.30 g/cm.sup.3, a
softness of 36 mm, a bonding strength more than 250 g/cm and a
ratio of the total weight of the non-woven fabric constituents to
the weight of the woven fabric constituent of 2.0.
The composite fabric could be converted, by the same process as
described in Example 1, into a nubuck-like artificial leather
having a smooth and dense pile layer.
COMPARATIVE EXAMPLE 4
A random web having weight of 200 g/m.sup.2 and consisting of
polyethylene terephthalate fibers with an average diameter of 2.0
microns was produced by using the same melt-blow process as that
utilized in Example 1, except that the extruding rate was 0.2
g/minute per orifice, the temperature of the steam stream was
385.degree. C. and the blowing pressure of the steam was 4.0
kg/cm.sup.2. The web had an area shrinkage of 40% in boiling water.
The random web was subjected to the same water-jetting process as
that used in Example 1, while a reduced pressure of 35 mmMg was
applied to the lower surface of the random web.
The resultant non-woven fabric was very soft and resilient and had
the following properties.
______________________________________ Density 0.20 g/cm.sup.3
Tensile strength 0.19 kg/mm.sup.2 Tear strength 1.1 kg Sewing
strength 1.3 kg/cm ______________________________________
That is, the non-woven fabric had a poor tensile strength. The
non-woven fabric was impregnated with 40%, based on the weight of
the fabric, of the same polyurethane elastomer and by the same
method as described in Example 1, and then immersed in boiling
water to shrink to an area shrinkage of 15%. Thereafter, the
resultant artificial leather was washed, dried and then raised with
sand paper to form a pile layer. The artificial leather had the
following properties.
______________________________________ Weight 280 g/m.sup.2 Tensile
strength 0.25 kg/mm Tear strength 1.5 kg Sewing strength 1.7 kg/cm
______________________________________
In spite of its beautiful appearance and feel, the artificial
leather had poor tensile strength, tear strength and sewing
strength.
COMPARATIVE EXAMPLE 5
Polyethylene terephthalate filaments having a denier of 2 which
correspond to a diameter of about 15 microns, were cut to provide
staple fibers having a length of 3.0 cm. Two pieces of webs having
weight of 80 g/cm.sup.2 were produced from the staple fibers by
using a carding engine. A cotton gauze fabric having a weight of 40
g/m.sup.2 was interposed between two pieces of the web. The
resultant three-layer precursory sheet was converted into a
composite fabric by using the same process as described in Example
1. The resulting composite fabric had a density of 0.18 g/cm.sup.3
and a softness of 62 mm.
The composite fabric was impregnated with 40%, based on the weight
of the composite fabric, of the same polyurethane elastomer by
using the same process as described in Example 1, and then raised
with sand paper.
The pile layers of the resultant raised fabric is composed of 2
denier piles and, therefore, had a sandy feel and a rough
appearance. Even when the pile layer was sheared to provide piles 1
to 2 mm long, the pile layer could not exhibit a chalk mark-forming
effect. The resultant fabric had the following properties.
______________________________________ Weight 280 g/m.sup.2 Density
0.24 g/cm.sup.3 Tensile strength 0.83 kg/mm.sup.2 Tear strength 3.1
kg Sewing strength 6.7 kg/cm Softness 68 mm
______________________________________
The resultant fabric could not be utilized as an artificial
leather.
COMPARATIVE EXAMPLE 6
The same three-layer precursory sheet as that obtained in Example 1
was needle-punched at a needling density of 500 punches/cm.sup.2.
During the needle-punching operation, a large amount of the
extremely fine fibers are removed from the precursory sheet. After
completion of the needle-punching process, numerous holes and dents
were found in the resultant composite fabric. Also, a portion of
the knitted fabric constituent appeared on the surface of the
composite fabric.
The composite fabric had the following properties.
______________________________________ Weight 160 g/m.sup.2
Thickness 0.94 mm Density 0.17 g/cm.sup.3 Tensile strength 0.35
kg/mm.sup.2 Tear strength 1.6 kg Sewing strength 4.2 kg/cm Recovery
on elongation 68% Compressibility 50% Recovery on compression 62%
Bonding strength 20 g/cm ______________________________________
The non-woven fabric constituent had a density of 0.12 g/cm.sup.3
and a tensile strength of 0.05 kg/mm.sup.2.
From the fact that the above shown tensile strength of the
non-woven fabric constituent is very poor, it is obvious that the
extremely fine fibers in the non-woven fabric constituent are
entangled at a very poor degree of a three-dimensional
entanglement. Also, from the low tensile strength of the composite
fabric, it is evident that a considerable amount of fibers in the
knitted fabric constituent are broken by needles during the
needle-punching process.
The composite fabric was impregnated with a polyurethane elastomer
by the same method as that mentioned in Example 1 and then
raised.
The resultant sheet had a paper-like appearance and feel and a poor
resiliency due to the low degree of the three-dimensional
entanglement of the fibers in the non-woven fabric constituents.
Furthermore, the resultant pile layer had a low density of piles
and an uneven appearance and feel, because the pile layer was
contaminated with thick piles derived from the fibers of the
knitted fabric constituent and because the surface of the non-woven
fabric constituent was unevenly buffed due to the existance of
holes and dents formed by the needle-punching process. The
resultant sheet could not be utilized as an artificial leather and
had the following properties.
______________________________________ Weight 210 g/m.sup.2 Density
0.20 g/cm.sup.3 Tensile strength 0.48 kg/mm.sup.2 Tear strength 1.9
kg Sewing strength 4.6 kg/cm Recovery on elongation 72%
Compressibility 45% Recovery on compression 67%
______________________________________
COMPARATIVE EXAMPLES 7, 8 AND 9
A random web having a weight of 150 g/m.sup.2 was produced from
polyethylene terephthalate chips by using the same melt-blow
process as used in Example 1. A woven fabric consisting of nylon 66
multifilament yarns of 120 denier/86 filaments and having a weight
of 80 g/m.sup.2 was fed onto a net spaced 15 cm (Comparative
Example 7), 20 cm (Comparative Example 8), and 40 cm (Comparative
Example 9) from the orifices and moving at a constant velocity. The
extremely fine fibers having an average diameter of 1.5 microns
were blown onto the woven fabric so as to form a two-layer
precursory sheet.
In the precursory sheet of Comparative Example 7, the resultant
extremely fine fibers melt-adhered to each other and to the fibers
in the woven fabric constituent. The precursory sheet of
Comparative Example 7 failed to be converted into a composite
fabric by the same water-jetting process as that used in Example
1.
In comparative Example 8, the melt-blown extremely fine fibers
melt-adhered to each other and to the fibers in the woven fabric
constituent, and the resultant precursory sheet was impregnated
with 40%, based on the weight of the composite fabric, of the same
polyurethane elastomer by using the same process as those described
in Example 1, and buffed with sand paper, without applying the
water-jetting process to the precursory sheet.
The resultant sheet had the following properties.
______________________________________ Weight 320 g/m.sup.2 Density
0.19 g/cm.sup.3 Tensile strength 0.72 kg/mm.sup.2 Tear strength 2.4
kg Sewing strength 5.2 kg/cm Recovery on elongation 65%
Compressibility 8% Recovery on compression 43% Softness 63 mm
Resistance to abrasion class 2 Bonding strength 100 g/cm
______________________________________
The sheet of Comparative Example 8 had a paper-like appearance, a
stiff feel and a low resiliency. Since the pile layer had a low and
uneven density of piles, this sheet, therefore, could not be
utilized as an artificial leather.
In the precursory sheet of Comparative Example 9, no melt-adhering
of the extremely fine fibers to each other and to the fibers in the
woven fabric constituent was observed. However, the precursory
sheet had a very poor bonding strength of 15 g/cm; therefore, the
woven fabric constituent could be easily separated from the
non-woven fabric constituent.
The precursory sheet was impregnated with 40%, based on the weight
of the sheet, of the same polyurethane elastomer by using the same
process as those described in Example 1, and buffed with sand paper
without using the water-jetting process for the precursory
sheet.
The resultant sheet had a paper-like appearance and feel and the
following properties.
______________________________________ Weight 320 g/m.sup.2 Density
0.17 g/cm.sup.3 Tensile strength 0.67 kg/mm.sup.2 Tear strength 2.2
kg Sewing strength 5.1 kg/cm Recovery on elongation 67%
Compressibility 11% Recovery on compression 45% Softness 38 mm
Resistance to abrasion class 2 Bonding strength 70 g/cm
______________________________________
The bonding strength of the sheet was extremely poor because a
number of air bubbles were formed on the intersurface between the
woven fabric constituent and the web constituent. Also, the sheet
had an appearance and feel similar to those of paper and low
resiliency. The pile layer of the sheet was extremely rough and
uneven; therefore, the sheet could not be used as an artificial
leather.
* * * * *