U.S. patent number 3,731,352 [Application Number 05/046,410] was granted by the patent office on 1973-05-08 for method of manufacturing a fibrous sheet.
This patent grant is currently assigned to Toray Industries, Inc.. Invention is credited to Keiichi Ashida, Toyohiko Hikota, Makoto Kounosu, Shungi Mizuguchi, Miyoshi Okamoto, Koji Watanabe.
United States Patent |
3,731,352 |
Okamoto , et al. |
May 8, 1973 |
METHOD OF MANUFACTURING A FIBROUS SHEET
Abstract
A method of manufacturing a fibrous sheet including an
application of a locational cutting operation to one or more
superimposed fibrous webby masses at a stage preceding the usual
needle punching operation thereon and a fibrous sheet manufactured
thereby having an internal configuration wherein numerous fine
fibers are three-dimensionally entangled with each other. The known
islands-in-a-sea type synthetic filaments are advantageously used
in the formation of the fibrous webby masses with later elimination
of the sea component.
Inventors: |
Okamoto; Miyoshi (Osaka,
JA), Watanabe; Koji (Otsu, JA), Ashida;
Keiichi (Kyoto, JA), Hikota; Toyohiko (Kyoto,
JA), Mizuguchi; Shungi (Otsu, JA), Kounosu;
Makoto (Otsu, JA) |
Assignee: |
Toray Industries, Inc. (Tokyo,
JA)
|
Family
ID: |
27542564 |
Appl.
No.: |
05/046,410 |
Filed: |
June 15, 1970 |
Current U.S.
Class: |
28/112; 19/.6;
19/6 |
Current CPC
Class: |
D04H
3/10 (20130101); D04H 18/02 (20130101) |
Current International
Class: |
D04H
3/10 (20060101); D04H 18/00 (20060101); D04H
3/08 (20060101); D04h 018/00 () |
Field of
Search: |
;28/72.2,76T ;161/80
;19/.6 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Rimrodt; Louis K.
Claims
What we claim is:
1. An improved method of manufacturing a non-woven fibrous sheet
comprising, in a sequential combination, forming a fibrous webby
mass from a plurality of continuous filamentary fibers and
thereafter repeatedly penetrating said mass with a multiplicity of
small spaced cutting instruments comprising needles having cutting
blade-formed points to effect locational cutting operations at
random locations to sever individual fibers of said mass into
random lengths, and subjecting the resulting fibrous webby mass of
random length fibers to a needling operation three dimensionally to
entangle said random length fibers with one another.
2. An improved method claimed in claim 1, wherein said random
locational cutting is carried out by pressing said webby fibrous
mass by a porous board and piercing blade-pointed cutting
instruments into said mass through holes of said porous board.
3. An improved method claimed in claim 1, wherein said random
locational cutting is performed in combination with a needle
punching operation.
4. An improved method claimed in claim 1, wherein said fibrous
webby mass is made up of fibers having a loop strength in a range
from 0.2 to 1.5 g/denier.
5. An improved method claimed in claim 1, wherein said fibrous
webby mass is made up of polymer blend filaments.
6. An improved method claimed in claim 1, wherein a plurality of
said fibrous webby masses are superposed and are subjected to said
locational cutting and needling operations while superposed.
7. An improved method claimed in claim 1, wherein said cutting
instruments are caused to penetrate said fibrous webby mass at an
inclined angle.
8. An improved method claimed in claim 1, wherein said continuous
filamentary fibers are deposited on a conveyor belt under pneumatic
suction force.
9. An improved method of manufacturing a non-woven fibrous sheet
comprising, in a sequential combination, forming a fibrous webby
mass from a plurality of islands-in-a-sea type continuous
filamentary fibers, repeatedly penetrating said mass with a
multiplicity of small spaced cutting instruments comprising needles
having cutting blade-formed points to effect locational cutting
operations at random locations to sever individual fibers of said
mass into random lengths, subjecting the resulting fibrous webby
mass of random length fibers to a needle punching operation three
dimensionally to entangle said random length fibers with one
another, and thereafter removing the sea component of said
islands-in-a-sea type filamentary fibers.
10. An improved method claimed in claim 9, wherein said
islands-in-a-sea type filamentary fiber is composed of island
components of from 0.001 to 0.5 denier fineness and sea component
having a loop strength of 1.5 g/d or smaller in a single filament
form.
11. An improved method claimed in claim 9, wherein said
islands-in-a-sea fiber contains discontinuous fine island
components of at least 1 cm length embraced by sea component having
a loop strength of 1.5 g/d or smaller in a single filament
form.
12. An improved method claimed in claim 9, wherein said needle
punched webby mass is impregnated with a water soluble polymeric
substance, said sea component is removed from said mass by a
solvent thereof, said mass is further impregnated with an elastic
polymeric substance and said water soluble polymeric substance is
removed from said mass simultaneously with or after coagulation of
said elastic polymeric substance.
13. An improved method claimed in claim 9, wherein a plurality of
said fibrous webby masses are superposed and are subjected to said
locational cutting and needling operations while superposed.
Description
The present invention relates to an improved method for
manufacturing a fibrous sheet and the resulting product, and more
particularly relates to an improved method for manufacturing a
fibrous sheet through employment of a locational cutting operation
applied to one or more superimposed fibrous webby masses prior to
the usual needle punching application and a fibrous sheet made
thereby made up of numerous three-dimensionally entangled fine
fibers.
The conventional fibrous sheets such as non-woven fabrics are
roughly classified into two typical types. In one type of fibrous
sheet, fibers are massed into a sheet form and are bonded or fused
to each other. In this type, no application of a punching operation
to the massed fibers is employed and therefore, fibers are not
entangled with each other to an appreciable extent in the internal
configuration of the fibrous sheet. For convenience in the ensuing
description, this type of fibrous sheet is herein named as
"non-entangled type." Another type of fibrous sheet is made up of
mutually, randomly and three-dimensionally entangled numerous fine
fibers. This entanglement of the fibers is effectuated by the
application of the needle punching operation to the fibrous mass.
This type of fibrous sheet will hereinafter be named as "entangled
type."
In the case of the non-entangled type fibrous sheet, the sheet is
made up of numerous fine fibers generally in the continuous
filamentary form. So, the sheet is provided with a lesser number of
fiber ends extending out of the surface thereof. This absence of
fiber ends on the surface degrades the handling quality of the
sheet, which handling quality is mostly dependent upon the presence
of numerous very fine fiber ends on the surface. Further, the
fibers are not entangled with each other to an appreciable extent
in the internal configuration of the sheet and the fibers composing
the sheet are liable to be separated therefrom by application of,
for example, an external abrasive force. In addition, the internal
configuration of the sheet of this type is essentially different
from that of the entangled type sheet. The componental fibers are
amalgamated together through mutual bonding or fusing but are not
entangled together to an appreciable extent. In other words, some
bonding or fusing agent is necessary to effectuate this
amalgamation.
Further, it should be noted that the non-entangled type fibrous
sheet contains less fibers running in the direction of the
thickness thereof and this absence of the fiber causes paper-like
handling of the end product. Poor entanglement of the componental
fibers requires making the fibrous web rather compact in order to
provide the product with enstrengthened binding. This results in
undesirably hard touch of the end product especially when a thick
construction is required.
On the other hand, in the case of the conventional entangled type
fibrous sheets, the componental fibers are supplied in the form of
short cut fibers. In some instances, needle punching is exerted on
a webby mass composed of fibers of non-continuous form. This is due
firstly to a difficulty in the needle punching operation on a webby
mass made up of continuous fibers. Such a needle punching operation
is frequently accompanied with accidental breakage of the punching
needles. Provided that long fibers are used in the formation of
this entangled type fibrous sheet, considerable difficulty in the
punching operation practically results. This difficulty leads to
the presence of fewer componental fibers running in the thickness
direction of the sheet. So, even application of a buffing operation
to the surface of the end product cannot assure raising of numerous
fibers ends on the surface and the obtained end product lacks the
suede like surface touch. In the needle punching operation, the
webby mass of short fibers is pierced by a plurality of hooked
punching needles so that the componental fibers are entangled with
each other in a direction inclined or perpendicular to the surface
of the mass. Therefore, the hooked punching needles tend to
accidentally break through their hooking of the fibers when the
componental fibers are supplied in a continuous filamentary form.
This frequent accidental needle breakage has formed a bar in the
practical manufacture of the fibrous sheets such as non-woven
fabrics using continuous filamentary fibers.
In order to overcome this difficulty, one of the conventional
processes involves crimping the drawn filaments, cutting the
crimped filaments after a pertinent oiling operation into a staple
form, forming a webby fibrous mass by passing thus obtained staple
fibers through cards, cross-lappers and random webbers and needle
punching the thusly obtained webby fibrous mass or masses. However,
this multiple staged process is accompained with an inevitable
increase in the production cost of the obtained products. Further,
when islands-in-a-sea type fibers are used, this type of process
tends to cause undesirable exposure of the island components for
example during the carding action and such exposure of the island
component tends to form a bar in the smooth punching operation.
There have been no creative methods for attaining desirable
entanglement of the usual synthetic continuous filamentary fibers
in the internal configuration of the fibrous sheet of the
above-described type.
It is supposed to be employable, in the formation of the fibrous
sheet, to take up the extruded filaments at a high speed, to cut
the filaments instantly into short fibers and to mass the cut
fibers into a sheet form. However, under the present day's
situation, none of the modern techniques can assure success in
cutting the filaments into short fibers of any desired fiber length
while processing the filaments at high speeds in a range from 3,000
to 7,000 MPM.
A principal object of the present invention is to provide a simple
method for manufacturing a fibrous sheet of a three-dimensionally
entangled internal configuration directly from continuous
filamentary fibers with lessened malfunctions such as punching
needle breakage or damage.
Another object of the present invention is to provide a fibrous
sheet durable against various types of external load applications
and having an excellent dimensional stability even through
long-time use under severe conditions.
In order to attain the above-recited objects, the method of the
present invention is characterized by firstly forming a fibrous
webby mass from a plurality of continuous filamentary fibers and
secondly, applying a locational cutting operation to one or more
superimposed fibrous webby masses so that the resultant fibrous
sheet is provided with a three-dimensionally entangled internal
configuration. Extremely fine fibers composing the resultant
fibrous sheet can be obtained by using the islands-in-a-sea type
fibers as the continuous filamentary fibers.
Further features and advantages of the present invention will be
made more apparent from the following description including some
examples, reference being made to the accompanying drawing, in
which;
FIGS. 1A to 1J are fragmentary front views of the cutting blades
used in the locational cutting operation in the method of the
present invention,
FIG. 2 is a schematic representation of a transversal cross section
of one embodiment of the islands-in-a-sea type fibers preferably
used in the manufacturing of the fibrous sheet of the present
invention,
FIG. 3 is a schematic side view of a device for measuring the loop
strength of the fibers used in a particular case of the method of
the present invention,
FIG. 4 is a graphical representation of the relationship between
the punching density and the number of needle breakages during the
needle punching operation.
The continuous filamentary fibers usable in the manufacturing
method of the present invention can be supplied in the form of any
of the conventionally known filaments such as filaments
manufactured in the melt-spinning system, dry spinning system or
wet spinning system. Further, the fibers can be supplied in the
form of composite filaments, polymer blend type filaments, emulsion
spinning type filaments, textured crimped filaments or
islands-in-a-sea type filaments. In this connection, however, the
process of the present invention is most desirably and
advantageously employed in combination with the manufacturing
process of the melt-spinning type filaments, polymer-blend type
filaments, composite filaments and islands-in-a-sea type filaments.
This is because the extruded filaments in the melt spinning process
can be taken up at speeds from 3000 to 8000 MPM with sufficient
orientation effect and such a high speed processing of the
filaments is well conformable to the relatively high speed
manufacturing of the fibrous sheet of the present invention.
Further, the configurationally modified filaments procured by the
above-mentioned techniques well contribute to the enrichment of the
bulkiness of the resultant fibrous sheet.
As to the mechanical nature of the continuous filamentary fibers,
their breaking elongation should advantageously be 12 percent or
larger, more particularly it should be 20 percent or larger in the
condition before being cut into short fibers. In case the breaking
elongation is smaller than 12 percent, the resultant fibrous sheet
is provided with a very hard handling quality such as a board and
further, wrinkles are liable to develop over its surface during use
thereof.
The above-recited material filamentary fibers may advantageously be
made up of such polyamides as nylon 6, nylon 66, nylon 610, nylon
7, nylon 8, nylon 9, nylon 11 or nylon 12; such polyesters as
polyethyleneterephthalate, polybutylene-terephthalate or
polyoxyethylene-benzoate; such polyolefins as polyethylene or
polypropylene; such polymers as polyvinyl-alcohol
polyacrylonitrile, polystyrene or polyurethane; or the derivatives
or copolymers of the above-recited polymers. Such additives as
dyestuffs, pigments, delusters or antistatic agents can also be
contained.
As the first stage of the manufacturing method of the present
invention, the selected filamentary fibers must be formed into a
webby fibrous mass. In the practical process of the webby mass
formation, the filaments are distributed over a collector belt
using an ejector or ejectors. In case the ejector is not used in
taking up the extruded filaments, this distribution of the
filaments is carried out using pneumatic flow and/or electro-static
force. For a better formation of the webby mass, it is recommended
to effect any pneumatic suction force from the underside of the
collector belt. At this stage of the filaments' distribution, it is
also desirable to mix such substances as water, oiling agent,
sizing bonding agent or filaments of low melting point to the webby
mass so as to mitigate the undesirable scattering and flying of the
distributed filamentary fibers outside the collector belt. In case
the filaments are already provided with potential crimps, crimp
development can be performed during or after this webby mass
formation, thereby entanglement of the fibers composing the mass
can be further increased. When required, the crimp development can
be carried out in the later stage of the fibrous sheet
manufacturing.
It is further recommended to form this webby mass from several
different kinds or types of fibers. This is also done by
amalgamating two or more sets of webby masses of different kinds or
types in a superimposed disposition. By the suitable introduction
of the above-described amalgamation of different kinds and/or types
of fibers or webby masses, the resultant bending characteristics of
the obtained fibrous sheet can be adjusted as desired.
After completion of the above-explained webby mass formation, the
webby mass obtained is next subjected to a locational cutting
operation. In this connection, two or more webby masses may be fed
in a superimposed disposition. By this application of the
locational cutting to the webby mass or masses, continuous
filamentary fibers in the mass or masses are cut into staple fibers
so that the subsequent punching operation can be performed
smoothly. This cutting is usually done by using needles having
blade-formed points or piercers having blade-formed points or
saw-teethed points. Knife-edged cutters can be used, also. Piercing
the above-described cutting device can be performed at random
locations of the webby mass. When any particular esthetic effect is
required on the surface of the resultant fibrous sheet, the cutting
is done at purposely selected locations. It is not always necessary
that the cutting devices pierce through the webby mass perfectly.
That is, in some instances, it is rather desirable for the
resultant fibrous sheet to contain some extent of uncut continuous
filamentary fibers. Presence of such survived continuous
filamentary fibers within the resultant fibrous sheet contributes
to the enrichment of the tensile strength of the obtained
product.
In order to mitigate the heterogeneity of the strength through the
configuration of the obtained fibrous sheet, it is advantageous to
effectuate this locational cutting operation in a direction
inclined to the surface of the webby mass, in other words, in a
direction not perpendicular to the surface of the webby mass. By
this employment of the inclined directional cutting, cut points of
the fibers can be randomly and rather uniformly distributed
throughout the internal configuration of the webby mass. This
inclined directional cutting is in general carried out in two ways.
In the first method, the cutting devices obliquely pierce into the
webby mass placed in a horizontal disposition whereas, in the
second method, the cutting devices vertically pierce into the webby
mass placed in an inclined disposition. In both cases, it is
preferable to place the webby mass in a stationary disposition and
move the cutting devices through a porous guide plate.
Several examples of the cutting blades used for this locational
cutting operation are shown in FIGS. 1A to 1J.
Subsequent to the locational cutting operation, the webby mass is
processed to a usual needle punching stage, which needle punching
is performed in a fashion conformable to the users' requirement for
the end product.
It should be understood that various modifications can be derived
from the above-described principal method for manufacturing the
fibrous sheet. For example, a needle punching of a moderate extent
can be applied to the webby mass prior to the application of the
locational cutting. By this application of moderate needle
punching, the continuous filamentary fibers still in a
non-entangled condition can be displaced rather freely in the
configuration of the webby mass. This disordering of the
componental fibers is helpful in enhancing the uniform distribution
of the cut points of the fibers in the configuration of the mass
after the application of the locational cutting operation. After
the cutting operation, a final needle punching is performed. When
required, this combination of needle punching and locational
cutting can be repeated several times.
In another modification, the above-mentioned locational cutting can
be attained by utilizing the usual needle punching operation
itself. In this case, the material fiber should preferably have a
loop strength of from 0.2 to 1.5 g/denier, or more preferably from
0.4 to 1.2 g/denier. When the loop strength exceeds this upper
limit value, increased needle breakage will occur whereas, when the
loop strength is smaller than this lower limit value, the obtained
fibrous felt cannot be provided with sufficient strength.
In this connection, the loop strength of the used fiber is measured
using the measuring device shown in FIG. 3, wherein a pair of
looped fibers of 2.5 cm loop length are hooked with each other and
the respective fiber loops 10 and 11 are pulled in the opposite
direction by the respective clamps 12 and 13. At the breakage of
the fiber loops, the strength of the fiber per unit denier is
recorded.
As is briefly mentioned in the foregoing description, the
islands-in-a-sea type fibers are very desirably used as the
filamentary fibers in the method of the present invention.
The term islands-in-a-sea type fibers as herein used is defined as
follows in reference to the illustration shown in FIG. 2, wherein a
perticular transversal cross section 1 of the fiber is composed of
a continuous sea component 2 and a plurality of island components 3
distributed at random within the sea component 2. Some of the
island components 3 are wholly embraced by the sea component 2
whereas some of the island components 3 may be only partly embraced
by the sea component 2. The island components 3 are elongated along
the lengthwise direction of the fiber in such a manner that the
number of the island components within a particular transversal
cross section is the same with that in other cross sections
remotely away from that particular cross section by 5 meters or
longer. The number of the island components should be 5 or more,
desirably 10 or more and further desirably 15 or more. The
transversal cross-sectional profile of the fiber may be round,
square, polygonal, flat square or elliptical.
As to the number of the island components within the particular
transversal cross section of the fiber, it should be 5 or more as
above-mentioned. When this number is fewer than 5, frequent needle
breakage during the punching operation tends to result. Further,
this causes relatively hard and rough handling quality of the
fibrous sheet obtained.
The fineness of the island component should be in a range from
0.001 to 0.5 denier. Fineness of the island component exceeding 0.5
denier oftentimes causes frequent needle breakage in the punching
operation and roughened surface touch with degraded handling
quality of the resultant fibrous sheet.
The percent total weight content of the island component in the
islands-in-a-sea type fiber should preferably be 55 percent or
smaller, more desirably be 30 percent or smaller. In case the
content exceeds 55 percent, it becomes difficult to spin the fiber
continuously for a long time, frequent needle breakage results in
the punching operation and the softness of the obtained fibrous
sheet is oftentimes degraded.
In addition to the already recited polymeric substances, the island
component may be made up of such fiber formable polymeric
substances as polyvinyl acetate, cellulose and its derivative,
polyether, polycarbonate or polyalkyl substituted
phenyleneoxide.
As to the mechanical property of the sea component, it is desirable
that the loop strength is 1.5 g/denier or smaller for a filament of
1 to 6 denier fineness and made up of the polymeric substance
composing the sea component. If a polymeric substance of larger
loop strength is used, it results in frequent needle breakage and
damage during the punching operation.
The kind and type of polymeric substance composing the sea
component should preferably be so selected that the polymeric
substance can be easily removed from the fiber by using any usual
solvent. For example, such polymeric substances are preferably used
as polyisopropylene capro-amide, polyethylene terephthalate, water
soluble polyamide, polystyrene, copolymer of polyethylene glycol,
rayon, acetate, triacetate, vinylidene chloride or
polymethylmethacrylate and its derivatives.
In case the above-explained islands-in-a-sea type fibers are used
in the formation of the webby mass, it is necessary to remove the
sea component from the fibrous mass in the later stage of the
manufacturing process, thereby the obtained fibrous sheet is
composed of three-dimensionally entangled numerous bundles of
extremely fine fibers converted from the island components. Removal
of the sea component can be done by using solvents such as, for
example, formic acid, sulfuric acid, benzene, xylene, toluene,
dimethyl formamide, dimethyl sulfoxide, acetone, water, alcohol or
alkaline solution.
In a modified embodiment of the method of the present invention,
the fibrous sheet made up of the islands-in-a-sea type fibers is
impregnated with a polymeric substance of a water soluble nature
after the completion of the cutting and the needle punching
operations. Next, the sea component is removed from the fibrous
sheet by the solvent application.
Further, the fibrous sheet is impregnated with polymeric substance
of elastic nature. Upon or after the solidification of the elastic
polymeric substance, the water-soluble polymeric substance is
removed from the fibrous sheet.
The merit and advantage ascertained through the employment of the
method of the present invention is as hereinafter described in
detail.
In the first place, because the cutting operation is applied to the
webby mass prior to the needle punching operation, the subsequent
needle punching can be carried out smoothly with lessened
operational troubles such as needle breakage or damage. Further, by
suitably changing the manner of cutting, the functional property of
the resultant fibrous sheet can be adjusted in conformity to the
requirements of the end use thereof. Owing to the smoothness in the
operation, a sufficient needle punching effect can be expected and
the undesirable partial separation of the fibrous sheet during the
actual use can be effectively obviated.
Next, owing to the sequentially continuous manufacturing process of
the present invention, the work required for manufacturing the
fibrous sheet can be remarkably reduced and simplified.
Thirdly, use of the islands-in-a-sea type fibers in the
manufacturing of the fibrous sheet introduces further advantages.
At the stage of the webby mass formation, fibers are supplied in
the form of continuous filaments and this considerably contributes
to the lessening of the unevenness in thickness of the obtained
webby mass. At the needle punching stage the sea component is not
yet removed from the webby mass and the individual islands-in-a-sea
type fiber still retains its relatively large fineness. This
assures an effective punching effect and the fibers are well
entangled with each other. After the removal of the sea component,
the fibrous sheet is composed of three-dimensionally entangled
numerous bundles of extremely fine fibers converted from the island
components. This particular internal configuration of the fibrous
sheet has excellent mechanical properties with enhanced handling
quality and surface touch. Further, the use of the islands-in-a-sea
type fibers in the present invention is far more advantageous over
the use of the known blend fibers. In the case of the blend fibers,
removal of the sea component merely results in disintegration of
the entire fiber configuration whereas, in case the island
components are removed therefrom, no extremely fine fibers such as
that obtained in the present invention can be acquired.
The fibrous sheet of the present invention is suited for such uses
as floor coverings, interior decoration, artificial leathers, felts
for paper making, warmth retainers, shock absorbers, belts or
bags.
The following examples are illustrative of the process of the
present invention but are not to be construed as limiting the
same.
EXAMPLE 1
A copolymer of styrene with acrylonitrile was used as the sea
component forming material whereas nylon 6 was used as the island
components forming material. Sixty parts by weight of the former
was amalgamated with 40 parts by weight of the latter. Both
material chips were molten at 285.degree.C in respective melters of
the spinning devices and both molten material were introduced, via
gear pumps, to a common spinning terminal having a nozzle
particularly designed for this purpose. The amalgamated materials
were extruded through the nozzle in the form of islands-in-a-sea
type filaments, each filament containing 16 island components in
its transversal cross section. The extruded filaments were taken up
at a speed of 1,000 MPM by the first godet roller and subsequently,
at a speed of 3,400 MPM by the second godet roller. A heater plate
maintained at a temperature of 110 .+-. 5.degree.C was provided in
between the two rollers. The individual filament was thereafter
introduced through an ejector utilizing a highly pressured air flow
and fibers of from 2 to 3 denier were obtained. Being entrained in
this pressured air flow, the thusly obtained fibers were
distributed in a webby form over a conveyer belt. At this moment,
an aqueous solution of adhesive oiling agent was added to the
fibrous mass for anti-static purposes. The conveyer belt moved so
that the unit weight of the web should be 350 g/m.sup.2 and the web
was processed through press rollers during movement of the belt.
The width of the web was controlled at about 40 cm. Numerous
lance-formed cutting needles having blades at their sharpened
points (see FIG. 1A) were mounted on a porous board and the board
was placed for several times in a pressure contact with the fibrous
web for cutting purposes. Cutting was performed at a cutting
density of in average from 5 to 10 times per 1 cm.sup.2 area.
Pneumatic suction was effected from underneath the belt for drying
the fibrous web. Subsequently, the fibrous web was subjected to
needle punching at a density of 450 needles per 1 cm.sup.2 area.
The needle punching could be performed very smoothly without any
needle breakage and the obtained fibrous sheet was provided with
desirable handling quality. The thickness of the obtained fibrous
sheet under 5 g/cm.sup.2 load application was 4.36 mm. The apparent
density of the fibrous mass calculated basing upon this value was
0.080 g/cm.sup.3 and the fibrous sheet in this condition was
provided with appreciable resiliency. The loop strength of the
fiber before cutting was 3.6 g/denier and the elongation thereof
was 27 percent.
The obtained fibrous sheet was impregnated with 10 percent
polyvinyl alcohol aqueous solution and dried. Removal of the sea
component was performed by immersing the fibrous sheet in a benzene
bath. After drying, the sheet was further impregnated with
dimethylformamide solution of polyurethane, whose solidification
was done in a water bath. Both surfaces of the obtained fibrous
sheet were subjected to a buffing operation by sand paper and the
property of the resulted fibrous sheet was as is shown in the
following table.
In a longidudinal In a lateral direction direction Strength in
kg/cm.sup.2 76.8 75.6 Elongation in % 79 111 Stress at 20%
elongation in kg/cm.sup.2 22.4 11.6
COMPARATIVE EXAMPLE 1
In the process of the preceding example, the cutting operation was
omitted and the fibrous web was directly subjected to the needle
punching operation. When the punching density was increased up to
100 punches/cm.sup.2, 13 needle breakage per 1 m.sup.2 area were
caused. In order to examine the effect by the punching condition,
the depth of the needle piercing was changed from 6 to 15 mm and it
was confirmed that increase in the piercing depth dilutes the
substantial punching effect. So, the needle piercing depth is
preferably in a range from 8 to 12 mm. But this needle piercing
depth tends to be accompanied with frequent needle breakage during
the punching operation.
For the purpose of comparison with the result in the preceding
example, the needle punching operation was carried out at a
punching density of 450 punches/cm.sup.2. The resulted fibrous
sheet was provided with tight superficial configuration but with
relatively slackened internal configuration. Therefore, the product
was provided with poor resilience against bending and application
of bending operation to the product developed paper-like creases on
its surface. The apparent density of the resultant fibrous sheet
was 0.043 g/cm.sup.3, which value apparently showed the relatively
slackened internal configuration of the obtained product.
EXAMPLE 2
The islands-in-a-sea type fibers different in their composition
from those used in Example 1 were used. That is, a blend of 95
percent by weight of polystyrene with 5 percent by weight of
polyethylene-glycol was used as the sea component forming material
and polyethyleneterephthalate was used as the island components
forming material. Sixty-five parts by weight of the former was
amalgamated with 35 parts by weight of the latter in the
islands-in-a-sea disposition and a fibrous sheet was manufactured
in a manner similar to that in Example 1.
The loop strength of the fiber used was 1.2 g/denier. In the
application of the needle punching, the needle piercing depth was
changed as in case of the comparative example 1. Three needle
breakages per 1 m.sup.2 surface area of the fibrous sheet were
resulted at the needle piercing depth of 14 mm. However, increase
of the piercing depth to 15 mm resulted only 1.3 needle breakages
per that unit surface area.
When the needle punching density was increased up to 1,000
punches/cm.sup.2, a small piece was cut off from the sheet and the
componental fibers were extracted therefrom by treating the piece
with a solvent of polystyrene. In this observation, it was
confirmed that majority of the componental fibers were about 10 cm
long. The apparent density of the felt was 0.123 g/cm.sup.3 and the
felt was as a whole provided with uniformly tight configuration.
The strength of the felt was 2.68 kg/cm.sup.2. However, after
removal of the polystyrene component through immersion in a carbon
tetrachloride bath, the felt was provided with a strength of 7.36
kg/cm.sup.2. From this result, it is supposed that the polystyrene
component contributes less to the strength of the entire fibrous
felt or that the polystyrene component rather functions to lower
the strength of the entire fibrous felt.
Application of needle punching operation to such a weak felt causes
undesirable breakage of the componental fibers. In order to obviate
such undesirable fiber breakages, punching needles having
particular blades should be used in this case. Needle breakage
during the punching operation can be obviated by merely lowering
the strength of the componental fibers. In the process of the
present invention, together with making the punching operation do
the part of fiber cutting, the relative fiber strength is increased
by removing the negative component after the completion of the
fiber entanglement and the end product is formed of fibers of
extremely fine nature. The end product can thusly be provided with
uniformly interlaced and strengthened internal configuration.
EXAMPLE 3
The islands-in-a-sea type fibers were composed of 65 parts by
weight of a blend of 95 percent by weight of polystyrene with 5
percent by weight of polyethyleneglycol and 35 parts by weight of
nylon 6. The manufacturing process was basically the same with that
employed the preceding example with the following exceptions.
Take-up speed of the first godet roller in MPM 500 Take-up speed of
the first godet roller in MPM 1450 Temperature of the heater plate
in .degree.C 110 - 120 Width of the web on the conveyer belt in cm
35 Unit weight of the web in g/cm.sup.2 458 Punching density in
needles per 1 cm.sup.2 area 1,000
The needle punching could be practiced without any trouble. The
loop strength of the fibers was 1.14 g/denier. The percent
compression of the needle punched felt under 20 g/cm.sup.2 load
application was 31, which fact proves that the felt was provided
with high density.
The fibrous sheet now in a felt form was next impregnated with 15
percent polyvinylalcohol aqueous solution, softly squeezed by
rollers and dried at 100.degree.C. Then, the fibrous sheet was
washed in a trichroethylene bath for removal of polystyrene and was
dried in a manner not to lower its bulky nature. The fibrous sheet
was further impregnated with a solution of polyurethane in
dimethylformamide and immersed in a water bath for coagulation.
Thereafter, the fibrous sheet was immersed in a hot water bath for
removal of polyvinylalcohol and dried. By the subsequent
application of buffing, raising and rubbing, the fibrous sheet was
converted into a deer skin-like fabric having remarkable softness,
air permeability and durability against bending fatigue.
EXAMPLE 4
Instead of the material filament used in Example 3,
islands-in-a-sea type filaments composed of 50 parts by weight of
polystyrene as the sea component and 50 parts by weight of
polyethylene-terephthalate as the islands were used. The loop
strength of the fiber was 1.5 g/denier. The fibrous sheet was
manufactured from these filaments in a manner the same as that in
Example 3 with no needle breakage during the needle punching
operation. The final product was also provided with excellent
qualities as in the case of the preceding examples.
COMPARATIVE EXAMPLE 2
Islands-in-a-sea type filaments were composed of 65 parts by weight
of nylon 6 and 35 parts by weight of polyethyleneterephthalate and
the manufacturing of the fibrous sheet was carried out in a manner
similar to that employed in Example 3 with the only exception being
that the extruded filaments were taken up at a speed of 500 MPM by
the first godet roller and at a speed of 1,750 MPM by the second
godet roller.
Omission of the cutting operation was accompanied with undesirable
frequent needle breakage to such an extent that needle punching
could not be practiced and the resultant fibrous sheet was provided
with degraded functional properties. The loop strength of the fiber
was 5.7 g/denier.
COMPARATIVE EXAMPLE 3
In the composition of the islands-in-a-sea type filament used in
Example 3, nylon 6 was replaced by polypropylene and a fibrous
sheet was manufactured in a similar manner with omission of the
cutting operation. Frequent needle breakage during the needle
punching operation together with the degraded quality of the end
products resulted.
The loop strength of the fiber was 2.5 g/denier. The needle
punching was accompanied with considerably frequent needle breakage
and the needle punching could hardly be performed at a density over
300 punches/cm.sup.2. The obtained non-woven fabric was provided
with considerable bulkiness and the density thereof was 0.033
g/cm.sup.3. Its strength was a mere 1.95 kg/cm.sup.2.
EXAMPLE 5
The content ratio of nylon 6 in the islands-in-a-sea type filaments
of Example 3 was changed variously and the loop strength of the
resultant fibers was measured for the respective content ratio
(percent by weight) as is shown in the following table.
Sample Percent by weight Loop strength of the number of content
ratio resultant fiber in of the island g/denier. component. 1 65
2.1 2 50 1.5 3 40 1.3 4 30 0.9 5 20 0.4
Webs are produced from the respective fibers in a manner the same
with that employed in Example 1 and the obtained web of 30 cm.
width and 10 m. length was subjected to a needle punching operation
at a needle piercing depth of 12 mm. and a punching pitch of 5 mm.
using punching needles of 36 count without application of
particular draft. The relationship obtained in between the selected
punching density and the number of needle breakages per 1 m.sup.2
surface area of the felt was as is shown in FIG. 4. As is clearly
seen from the result shown in the drawing, the number of the needle
breakages increases suddenly at the loop strength of 1.5 g/denier.
The larger is the frequency of the needle breakage, the lower is
the quality of the end product. It was observed that, when the
frequency of the needle breakage increases, there is a separation
of the nylon 6 island components from the polystyrene sea component
and the extremely fine nylon 6 fibers are exposed on the surface of
the fiber without being cut. This proves the fact that the increase
in the strength of the fiber makes the cutting by the needle
punching more difficult.
EXAMPLE 6
As in the usual case, polyethyleneterephthalate was melt spun into
fibers and the produced fibers were, with drawing in between the
godet rollers, taken up by the ejector for dispersion on the
conveyer belt. The obtained fiber had a fineness of 2.3 denier and
a loop strength of 4.2 g/denier. The webby mass of fibers on the
conveyer belt was subjected to a thermal pressing at a temperature
of 160.degree.C and, next, subjected to a cutting operation by the
cutting blades such as shown in FIG. 1C planted in a board moving
up and down. The density of this locational cutting was 7
punches/cm.sup.2. The locationally cut web was further subjected to
a subsequent needle punching operation at a punching density of
1200 punches/cm.sup.2 and a needle piercing depth of 10 mm. using
punching needles of 40 count. The frequency of the needle breakage
was 2.3 per 1 m.sup.2 surface area of the web.
The obtained felt was provided with a density of 0.152 g/cm.sup.3,
a unit weight of 386 g/cm.sup.2 and a strength of 17 kg/cm.sup.2
and was further provided with excellent resilience particularly
suited for use as pads for base material for carpets. When the web
was subjected directly to the needle punching without application
of the preliminary locational cutting, a punching density of 50
punches/cm.sup.2 was accompanied with up to 19 needle breakages per
1 m.sup.2. surface area, which frequency was too large to carry the
punching operation further.
EXAMPLE 7
In Example 2, polystyrene was used as the sea component at a
content ratio of 50 parts by weight and the loop strength of the
fibers was 2.8 g/denier. A web composed of this fiber was subjected
to a needle punching on a needle punching machine having
needle-shaped blades planted together with needles in the needle
board. 10 m length of the web was processed through this needle
punching simultaneously with cutting at a punching density of 700
punches/cm.sup.2 and only seven needle breakages resulted.
The obtained felt was heated within a dry atmosphere of
120.degree.C temperature for 10 minutes and was impregnated with 20
percent polyvinylalcohol aqueous solution of 50.degree.C
temperature. Drying was performed at a temperature of 140.degree.C.
After this drying, the imparted polyvinylalcohol was mostly
contained within the superficial part of the felt and the inner
part of the felt was provided with less of this substance. The
thusly obtained felt was sliced at the middle thickness portion in
the surface direction and the sliced felt was impregnated with 15
percent dimethylformamide solution of polyurethane. Solidification
of the polyurethane component was performed by perfectly washing
the felt with hot water. Both surfaces of the sliced felt were
subjected to a raising operation, thereby one of the raised surface
was provided with numerous shortly raised resilient fiber ends and
the other of the raised surfaces was provided with raised fiber
ends of soft touch. The obtained felt was provided with a
particular softness together with a very natural leather like
handling quality.
EXAMPLE 8
Seventy parts by weight of nylon 6 and 30 parts by weight of
polyethylenephthalate were mixed together in the status of polymer
chips and the mixture was spun at a spinning temperature of
285.degree.C. After extrusion of the spinneret, the spun filaments
were taken up by an ejector at a location 30 cm downstream of the
spinneret and were uniformly distributed over a conveyer belt. The
fineness of thusly obtained fibers were in a range from 0.6 to 4.0
denier and its average loop strength was 3.2 g/denier. A web of 320
g/m.sup.2 unit weight was produced of these fibers and the web was
subjected to a locational cutting operation at a punching density
of 23 punches/cm.sup.2 using punching needles such as shown in FIG.
1A. In succession the locationally cut felt was subjected to a
needle punching operation at a punching density of 1,000
punches/cm.sup.2 using needles of 40 count and only 0.92 needle
breakages/m.sup.2 resulted. The density of the obtained felt was
0.117 g/cm.sup.3, which value shows that the obtained felt was
provided with a dense internal configuration and enhanced
resilience. When the locational cutting operation was omitted,
there resulted considerably frequent needle breakages at a punching
density of 350 punches/cm.sup.2 and the density of the felt was
0.033 g/cm.sup.3, which value apparently shows that the obtained
felt was provided with undesirably slackened construction.
EXAMPLE 9
In Example 8, polystyrene was substituted for nylon 6. The fineness
of the obtained fiber was in average 1.7 denier and the loop
strength thereof was 0.78 g/denier. A web of 550 g/m.sup.2 unit
weight was produced of these fibers. The obtained web was subjected
to a needle punching at a punching density of 300 punches/cm.sup.2
and a needle piercing depth of 12 mm using needles of 32 count.
Next, the punched felt was further subjected to an additional
needle punching operation using punching needles of 40 count until
the total needle punching density became 1200 punches/cm.sup.2.
Except for a few needle breakages at the initiating stage of the
punching operation, the whole needle punching operation could be
performed without any particular malfunctions. The obtained felt
was provided with a density of 0.157 g/cm.sup.3.
The felt was impregnated with 10 percent aqueous solution of
polyvinylalcohol and, after drying, was further immersed into a
trichloroethylene bath. Next, the felt was further impregnated with
dimethylformamide solution of polyurethane partly containing amino
acid resin, solidified and dried. One hundred and fifty-three parts
by weight of polyurethane was imparted to 100 parts by weight of
fibrous component. The obtained fibrous felt had a strength of 51
kg/cm.sup.2, an elongation of 141 percent a stress at 20 percent
elongation of 36 kg/cm.sup.2 and a very natural leather like soft
handling quality.
In the practical utilization of the method of the present
invention, it is also desirable to use polymer blend filaments
which are obtained by blend spinning at least two component
polymers. In this case, it is desirable that, in the internal
configuration of the filaments, at least one of the components
should elongate more than 1 cm. along the length of the
filament.
Although the above-described fibrous sheet composed of the
islands-in-a-sea type filamentary fibers provides many advantages
over the conventional fibrous sheets such as artificial leather or
non-woven fabrics, it is still inferior in its internal
configuration, dimensional stability and easiness in its
processability when compared with the natural collagen fibers. This
inferiority of the islands-in-a-sea type filamentary fibers can be
improved by application of a pertinent thermal treatment to the
webby mass after the entanglement of the fibers in the mass. In
this thermal treatment, the internally entangled webby fibrous mass
is subjected to a thermal application at temperatures higher than
the drawing temperature of the fibers or higher than the
crystallization or compactness temperature, temperature of the
island component forming material for a period longer than the
drawing time. In this connection, it is especially desirable to
form the webby mass from the fibers containing the island
components in an imperfectly crystallized state. Then, by the
application of the above-described thermal treatment, the
crystallization of the island components is well promoted, thereby
the fibers shrink in the internal configuration of the webby mass
for enhancing the compactness of the entangled fibrous
configuration of the webby mass.
* * * * *