U.S. patent application number 14/889970 was filed with the patent office on 2016-06-23 for organic resin non-crimped staple fiber.
This patent application is currently assigned to TEIJIN LIMITED. The applicant listed for this patent is TEIJIN LIMITED. Invention is credited to Noritaka BAN, Hironori GODA, Shinichi TAKAHASHI.
Application Number | 20160177476 14/889970 |
Document ID | / |
Family ID | 51988775 |
Filed Date | 2016-06-23 |
United States Patent
Application |
20160177476 |
Kind Code |
A1 |
BAN; Noritaka ; et
al. |
June 23, 2016 |
ORGANIC RESIN NON-CRIMPED STAPLE FIBER
Abstract
The present invention is intended to provide an organic resin
non-crimped staple fiber that has notably few defects and that
uniformly disperses in a dispersion medium, and that is preferred
for use in wet-laid nonwoven fabrics or resin reinforcement in
applications such as in industrial materials and daily commodities.
The organic resin non-crimped staple fiber of the present invention
has a fineness of 0.0001 to 0.6 decitex, a fiber length of 0.01 to
5.0 millimeters, a moisture content of 10 to 200 weight %, a
cut-end coefficient of 1.00 to 1.40, and a coefficient of variation
relative to fiber length (CV %) of 0.0 to 15.0%, the cut-end
coefficient and the coefficient of variation relative to fiber
length being defined as follows: (1) Cut-End Coefficient=b/a,
wherein a is the fiber diameter of a single yarn of the non-crimped
staple fiber, and b is the maximum diameter at the cut end; (2)
Coefficient of Variation Relative to Fiber Length (CV %)=(standard
deviation of fiber length)/(mean value of fiber
length).times.100(%), wherein the number of measured single yarns
is 50 in (1) and (2). The foregoing object can be achieved with
this configuration.
Inventors: |
BAN; Noritaka; (Ehime,
JP) ; GODA; Hironori; (Ehime, JP) ; TAKAHASHI;
Shinichi; (Yamaguchi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TEIJIN LIMITED |
Osaka |
|
JP |
|
|
Assignee: |
TEIJIN LIMITED
Osaka-shi, Osaka
JP
|
Family ID: |
51988775 |
Appl. No.: |
14/889970 |
Filed: |
May 27, 2014 |
PCT Filed: |
May 27, 2014 |
PCT NO: |
PCT/JP2014/063980 |
371 Date: |
November 9, 2015 |
Current U.S.
Class: |
428/373 ;
428/401 |
Current CPC
Class: |
D10B 2321/02 20130101;
D10B 2331/04 20130101; D01F 8/04 20130101; D01F 6/62 20130101; D04H
1/00 20130101; D04H 1/435 20130101; D01F 6/605 20130101; D04H 1/54
20130101; D01F 6/04 20130101; D10B 2331/021 20130101; D01D 5/26
20130101; D01G 1/04 20130101; D04H 1/4326 20130101 |
International
Class: |
D01G 1/04 20060101
D01G001/04; D04H 1/00 20060101 D04H001/00; D01F 6/62 20060101
D01F006/62; D01F 8/04 20060101 D01F008/04; D01F 6/04 20060101
D01F006/04; D01F 6/60 20060101 D01F006/60 |
Foreign Application Data
Date |
Code |
Application Number |
May 30, 2013 |
JP |
2013-114241 |
Sep 25, 2013 |
JP |
2013-198500 |
Claims
1-4. (canceled)
5. An organic resin non-crimped staple fiber for wet-laid nonwoven
fabrics, the organic resin non-crimped staple fiber having a
fineness of 0.0001 to 0.6 decitex, a fiber length of 1.0 to 5.0
millimeters, a moisture content of 10 to 100 weight %, a cut-end
coefficient of 1.00 to 1.40, and a coefficient of variation
relative to fiber length (CV %) of 0.0 to 15.0%, the cut-end
coefficient, and the coefficient of variation relative to fiber
length being defined as follows: Cut-End Coefficient=b/a, (1)
wherein a is the fiber diameter of a single yarn of the non-crimped
staple fiber, and b is the maximum diameter at the cut end;
Coefficient of Variation Relative to Fiber Length(CV %)=(standard
deviation of fiber length)/(mean value of fiber
length).times.100(%), (2) wherein the number of measured single
yarns is 50 in (1) and (2).
6. The organic resin non-crimped staple fiber according to claim 5,
wherein the non-crimped staple fiber is a polyester non-crimped
staple fiber, a wholly aromatic polyamide non-crimped staple fiber,
or a polyolefin non-crimped staple fiber.
7. The organic resin non-crimped staple fiber according to claim 5,
wherein the non-crimped staple fiber is a polyethylene
terephthalate non-crimped staple fiber, a polytrimethylene
terephthalate non-crimped staple fiber, a polytetramethylene
terephthalate non-crimped staple fiber, a polyethylene naphthalate
non-crimped staple fiber, a polytrimethylene naphthalate
non-crimped staple fiber, a polytetramethylene naphthalate
non-crimped staple fiber, a meta-type wholly aromatic polyamide
non-crimped staple fiber, a para-type wholly aromatic polyamide
non-crimped staple fiber, a polyethylene non-crimped staple fiber,
or a polypropylene non-crimped staple fiber.
8. The organic resin non-crimped staple fiber according to claim 5,
wherein the non-crimped staple fiber is a conjugate fiber
configured from two or more organic resins.
9. The organic resin non-crimped staple fiber according to claim 6,
wherein the non-crimped staple fiber is a polyethylene
terephthalate non-crimped staple fiber, a polytrimethylene
terephthalate non-crimped staple fiber, a polytetramethylene
terephthalate non-crimped staple fiber, a polyethylene naphthalate
non-crimped staple fiber, a polytrimethylene naphthalate
non-crimped staple fiber, a polytetramethylene naphthalate
non-crimped staple fiber, a meta-type wholly aromatic polyamide
non-crimped staple fiber, a para-type wholly aromatic polyamide
non-crimped staple fiber, a polyethylene non-crimped staple fiber,
or a polypropylene non-crimped staple fiber.
Description
TECHNICAL FIELD
[0001] The present invention relates to an organic resin
non-crimped staple fiber having uniform dispersibility in
media.
BACKGROUND ART
[0002] Wet-laid nonwoven fabrics made from a raw material that is
partially or fully a staple fiber (as a short fiber as it is also
called) obtained from a wholly aromatic polyamide having desirable
properties such as mechanical characteristics, electrical
characteristics, heat resistance, flame-retardation, and
dimensional stability, or from more cost advantageous polyester are
used in applications such as in electrical insulation paper, and a
cleaning web for copiers (see, for example, PTL 1). Such wet-laid
nonwoven fabrics are also used in a wide range of applications,
including industrial materials such as reinforcing materials for
resin molded products, and daily commodities. The increasing demand
for more flexible, thinner and denser nonwoven fabrics has created
a demand to increase the fineness of organic resin stable fibers
used for the wet-laid nonwoven fabrics. In order to make a thin and
dense nonwoven fabric, the dispersibility of the stable fiber in a
dispersion medium needs to be improved for the formation of the
wet-laid nonwoven fabric. This requires further reducing the fiber
length of the stable fiber.
[0003] However, the fibers become more likely to intertangle as
they become finer and increase the aspect ratio (fiber
length-to-fiber diameter ratio). A nonwoven fabric made with such
fibers tends to involve fluff ball defects. Such defects can be
circumvented by reducing the fiber length and keeping the aspect
ratio small. While this can reduce the fluff ball defects due to
intertangling of fibers, defects at the cut-end of the fibers cause
the stable fibers to be entangled with each other and aggregate,
with the result that the product (e.g., nonwoven fabric) becomes
defective. Ultrafine fibers of 0.6 decitex or less can be cut into
essentially any fiber length as short as less than 1 millimeter
with a known guillotine cutter. Specifically, the aspect ratio can
be reduced. However, for reasons related to the mechanism of the
cutting equipment, the fibers cannot be adequately held during the
cutting procedure, and easily produce cut-end defects (see, for
example, PTL 2). Stable fibers with the cut-end defects become
entangled with each other and aggregate, and cause defects in
nonwoven fabrics or reinforcing materials, making the final product
defective. Particularly, when an organic resin with high fiber
strength is used, the very high friction that occurs between the
resin and the metal when cutting the fiber may quickly make the
cutter blade blunt. Fine stable fibers also tend to involve cut-end
defects such as projecting ends, and an obliquely cut surface
relative to the fiber axis. Currently, for technical reasons, no
non-crimped stable fibers are available that use organic resins
having few dispersion defects. On the other hand, inventions are
known concerning uniform fibers with small distributions of fiber
diameters and fiber lengths, and fiber paper that use a fiber
characterized by the shapes of its projecting portions (see PTL 3,
4, and 5).
CITATION LIST
Patent Literature
PTL 1: JP-A-2011-232509
PTL 2: JP-A-2009-221611
PTL 3: JP-A-2007-092235
PTL 4: JP-A-2000-119989
PTL 5: JP-A-2001-295191
SUMMARY OF INVENTION
Technical Problem
[0004] The present invention was made under these circumstances,
and the invention is concerned with an organic resin non-crimped
staple fiber (stable fiber) that uniformly disperses in a medium
without causing aggregation defects.
Solution to Problem
[0005] The present inventors conducted intensive studies to solve
the foregoing problems, and arrived at using the following
configurations as a solution to the foregoing problems.
[0006] 1. The present invention was completed on the basis of the
finding that the defects can be reduced with an organic resin
non-crimped staple fiber having a fineness of 0.0001 to 0.6
decitex, a fiber length of 0.01 to 5.0 millimeters, a moisture
content of 10 to 200 weight %, a cut-end coefficient of 1.00 to
1.40, and a coefficient of variation relative to fiber length (CV
%) of 0.0 to 15.0%, the cut-end coefficient and the coefficient of
variation relative to fiber length being defined as follows:
Cut-End Coefficient=b/a, (1)
wherein a is the fiber diameter of a single yarn of the non-crimped
staple fiber, and b is the maximum diameter at the cut end;
Coefficient of Variation Relative to Fiber Length (CV %)=(standard
deviation of fiber length)/(mean value of fiber
length).times.100(%), (2)
[0007] wherein the number of measured single yarns is 50 in (1) and
(2).
[0008] Preferably, the present invention has the following
configurations.
[0009] 2. The organic resin non-crimped staple fiber according to
the 1 above, wherein the non-crimped staple fiber is a polyester
non-crimped staple fiber, a wholly aromatic polyamide non-crimped
staple fiber, or a polyolefin non-crimped staple fiber.
[0010] 3. The organic resin non-crimped staple fiber according to
the 1 or 2 above, wherein the non-crimped staple fiber is a
polyethylene terephthalate non-crimped staple fiber, a
polytrimethylene terephthalate non-crimped staple fiber, a
polytetramethylene terephthalate non-crimped staple fiber, a
polyethylene naphthalate non-crimped staple fiber, a
polytrimethylene naphthalate non-crimped staple fiber, a
polytetramethylene naphthalate non-crimped staple fiber, a
meta-type wholly aromatic polyamide non-crimped staple fiber, a
para-type wholly aromatic polyamide non-crimped staple fiber, a
polyethylene non-crimped staple fiber, or a polypropylene
non-crimped staple fiber.
[0011] 4. The organic resin non-crimped staple fiber according to
any one of the 1 to 3 above, characterized in that the non-crimped
staple fiber is a conjugate fiber configured from two or more
organic resins.
Advantageous Effects of Invention
[0012] The present invention enables uniformly dispersing a
non-crimped staple fiber of organic resin in a dispersion medium,
and reducing generation of an aggregated clump in using a
non-crimped staple fiber for wet-laid nonwoven fabrics or staple
fiber reinforced resins. The nonwoven fabric or other products made
from such non-crimped staple fibers contain staple fibers uniformly
dispersed therein. The product nonwoven fabric is thus free from
defects such as microscopic nonuniform dispersion of staple fibers,
and variation of basis weight and thickness, and can have desirable
properties such as uniform breathability and liquid permeability.
The final product produced by processing such nonwoven fabrics
involves few defects, and can have physical properties with
improved reliability (reliable product warranty). The yield of the
interim product (e.g., nonwoven fabric, and resin molded body) also
can improve. The present invention is thus also highly advantageous
in terms of resource saving and economy.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 is a schematic view at the cut end of an organic
resin non-crimped staple fiber of the present invention.
REFERENCE NUMERAL IN DRAWINGS
[0014] a: Fiber diameter of a single yarn [0015] b: Maximum width
of the fiber at the cut-end (maximum diameter when the cut-end has
a circular or a substantially circular shape)
DESCRIPTION OF EMBODIMENTS
(Organic Resin Composition)
(Polyester)
[0016] Embodiments of the present invention are described below in
detail. First, use of polyester as a specific example of the
organic resin of the present invention is described. For example,
the polyester is any of polyesters of aromatic dicarboxylic acid
and aliphatic diol, including, for example, polyalkylene
terephthalates such as polyethylene terephthalate, polytrimethylene
terephthalate, and polybutylene terephthalate (polytetramethylene
terephthalate), and polyalkylene naphthalates such as polyethylene
naphthalate, polytrimethylene naphthalate, and polybutylene
naphthalate (polytetramethylene naphthalate). Other examples
include polyesters obtained from alicyclic dicarboxylic acid and
aliphatic diol such as polyalkylene cyclohexane dicarboxylate,
polyesters obtained from aromatic dicarboxylic acid and alicyclic
diol such as polycyclohexane dimethylene terephthalate, polyesters
obtained from aliphatic dicarboxylic acid and aliphatic diol such
as polyethylene succinate, polybutylene succinate, and polyethylene
adipate, and polyesters obtained from polyhydroxycarboxylic acid
such as polylactic acid, and polyhydroxybenzoic acid.
[0017] Other examples include copolymers and blends containing
these polyester components in any proportions. According to the
intended purpose, one or more dicarboxylic acid components may be
copolymerized. Examples of such components include isophthalic
acid, phthalic acid, alkali metal salts of 5-sulfoisophthalic acid,
quaternary ammonium salts of 5-sulfoisophthalic acid, quaternary
phosphonium salts of 5-sulfoisophthalic acid, succinic acid, adipic
acid, suberic acid, sebacic acid, cyclohexane dicarboxylic acid,
.alpha.,.beta.-(4-carboxyphenoxy)ethane, 4,4-dicarboxyphenyl,
2,6-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic
acid, 1,3-cyclohexane dicarboxylic acid, 1, 4-cyclohexane
dicarboxylic acid, and diester compounds of these organic groups of
1 to 10 carbon atoms. According to the intended purpose, one of
more diol components may be copolymerized. Examples of such
components include diethylene glycol, 1,2-propanediol,
1,2-butanediol, 1,3-butanediol, 1,6-hexanediol, neopentyl glycol,
1,4-cyclohexane dimethanol,
2,2-bis(p-.beta.-hydroxyethylphenyl)propane, polyethylene glycol,
poly(1,2-propylene)glycol, poly(trimethylene)glycol, and
poly(tetramethylene)glycol. It is also possible to form a branch by
copolymerizing one or more components selected from
.omega.-hydroxyalkylcarboxylic acid, pentaerythritol,
trimethylolpropane, trimellitic acid, and hydroxycarboxylic acids
such as trimesic acid, or compounds with three or more carboxylic
acid components or hydroxyl groups. The polyester also includes
mixtures of these and other polyesters of different
compositions.
(Wholly Aromatic Polyamide: Meta-Type Wholly Aromatic
Polyamide)
[0018] The following describes use of wholly aromatic polyamide as
a specific example of the organic resin forming the organic resin
non-crimped staple fiber of the present invention. A meta-type
wholly aromatic polyamide staple fiber is described as an exemplary
embodiment of the wholly aromatic polyamide staple fiber. The
meta-type wholly aromatic polyamide as a raw material of the
meta-type wholly aromatic polyamide staple fiber used for the
organic resin non-crimped staple fiber of the present invention is
configured from a meta-type aromatic diamine component and a
meta-type aromatic dicarboxylic acid component, and may be
copolymerized with other copolymer component, such as a para-type
component, provided that it does not interfere with the objects of
the present invention.
[0019] For mechanical characteristics and heat resistance,
particularly preferred for use in the present invention are
meta-type wholly aromatic polyamides that contain a m-phenylene
isophthalamide unit as a primary component. The meta-type wholly
aromatic polyamides configured from a m-phenylene isophthalamide
unit preferably contain the m-phenylene isophthalamide unit in 90
mol % or more, more preferably 95 mol % or more, particularly
preferably 100 mol % of the total repeating unit.
[0020] Examples of the meta-type aromatic diamine component as a
raw material of the meta-type wholly aromatic polyamide include
m-phenylenediamine, 3,3'-diaminodiphenyl ether,
3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenyl ether,
3,4'-diaminodiphenylsulfone, and derivatives thereof having a
substituent such as halogen, C.sub.1-3 alkyl, and C.sub.1-3 alkoxy
in one or two of the aromatic rings of these aromatic diamine
compounds. Specific examples include 2,4-tolylenediamine,
2,6-tolylenediamine, 2,4-diaminochlorobenzene, and
2,6-diaminochlorobenzene. Particularly preferred are wholly
aromatic diamine components containing only m-phenylenediamine, or
70 mol % or more of m-phenylenediamine as the meta-type aromatic
diamine component.
[0021] Examples of the meta-type aromatic dicarboxylic acid
component as a raw material of the meta-type wholly aromatic
polyamide include meta-type aromatic dicarboxylic acid dihalides.
Examples of the meta-type aromatic dicarboxylic acid dihalides
include isophthalic acid dihalides such as isophthalic acid
dichloride, isophthalic acid bromide, isophthalic acid diiodide,
and derivatives thereof having a substituent such as halogen,
C.sub.1-3 alkyl, C.sub.1-3 alkoxy in the aromatic rings, for
example, such as 3-chloroisophthalic acid dichloride, and
3-methoxyisophthalic acid dichloride. Particularly preferred are
wholly aromatic dicarboxylic acid dihalides that contain only
isophthalic acid dichloride, or 70 mol % or more of isophthalic
acid dichloride.
(Wholly Aromatic Polyamide: Copolymer Components of Meta-Type
Wholly Aromatic Polyamide)
[0022] The following copolymer components may be used other than
the foregoing meta-type aromatic diamine components and meta-type
aromatic dicarboxylic acid components. Example of aromatic diamines
as such copolymer components include benzene derivatives (such as
p-phenylenediamine, 2,5-diaminochlorobenzene,
2,5-diaminobromobenzene, and
aminoanisidine(2-amino-4-methoxyaniline)), 1,5-naphthylenediamine,
1,6-naphthylenediamine, 4,4'-diaminodiphenyl ether,
4,4'-diaminodiphenylketone, 4,4'-diaminodiphenylamine, and
4,4'-diaminodiphenylmethane. Examples of aromatic dicarboxylic acid
components as copolymer components include terephthalic acid
dichloride, 1,4-naphthalene dicarboxylic acid dichloride,
2,6-naphthalene dicarboxylic acid dichloride, 4,4'-biphenyl
dicarboxylic acid dichloride, and 4,4'-diphenyl ether dicarboxylic
acid dichloride. These copolymer components are contained in
preferably 20 mol % or less of the total dicarboxylic acid
component of the meta-type wholly aromatic polyamide because the
properties of the meta-type wholly aromatic polyamide tend to
deteriorate when the copolymerization ratio of these copolymer
components is too high. Particularly, the meta-type wholly aromatic
polyamide is preferably a polyamide containing the m-phenylene
isophthalamide unit in 90 mol % or more of the total repeating
unit, particularly preferably poly m-phenylene isophthalamide.
(Wholly Aromatic Polyamide: Para-Wholly Aromatic Polyamide)
[0023] The following describes use of a para-type wholly aromatic
polyamide staple fiber as an embodiment of the staple fiber made of
wholly aromatic polyamide. Examples of the para-type wholly
aromatic polyamide as a raw material of the para-type wholly
aromatic polyamide staple fiber used as an example of the organic
resin non-crimped staple fiber of the present invention include
para-type wholly aromatic polyamides of polyparaphenylene
terephthalamide or polyparaphenylene terephthalamide copolymerized
with 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether,
4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenylsulfone,
3,4'-diaminodiphenylsulfone, or 4,4'-diaminodiphenylsulfone, and
para-type wholly aromatic polyamides copolymerized with small
quantities of isophthalic acid or m-phenylenediamine. Preferred are
copolyparaphenylene-3,4'-oxydiphenylene terephthalamide, and
polyparaphenylene terephthalamide. More preferred is
copolyparaphenylene-3,4'-oxydiphenylene terephthalamide, a wholly
aromatic polyamide containing terephthalic acid as an acid
component, and a mixed diamine component containing 40 mol % or
more of p-phenylenediamine and 40 mol % or more of
3,4'-diaminodiphenyl ether.
[0024] Examples of the aromatic diamine component that can be used
for the para-type wholly aromatic polyamide include
p-phenylenediamine, 4,4'-diaminodiphenyl ether,
4,4'-diaminodiphenylsulfone, and derivatives thereof having a
substituent such as halogen, C.sub.1-3 alkyl, C.sub.1-3 alkoxy in
one or two of the aromatic rings of these aromatic diamine
compounds. Specific examples include 2,5-tolylenediamine,
2,5-diaminochlorobenzene, and 2,5-diaminobromobenzene. Particularly
preferred are wholly aromatic diamine components that contain only
p-phenylenediamine, or 70 mol % or more of p-phenylenediamine as
the para-type aromatic diamine component.
[0025] Examples of the para-type aromatic dicarboxylic acid
component as a raw material of the para-type wholly aromatic
polyamide include para-type aromatic dicarboxylic acid dihalides.
Examples of the para-type aromatic dicarboxylic acid dihalides
include terephthalic acid dihalides such as terephthalic acid
dichloride, terephthalic acid bromide, and terephthalic acid
diiodide, and derivatives thereof having a substituent such as
halogen, C.sub.1-3 alkyl, and C.sub.1-3 alkoxy in the aromatic
rings, for example, such as 3-chloroterephthalic acid dichloride,
and 3-methoxyterephthalic acid dichloride. Particularly preferred
are wholly aromatic dicarboxylic acid dihalides that contain only
terephthalic acid dichloride, or 70 mol % or more of terephthalic
acid dichloride.
(Wholly Aromatic Polyamide: Copolymer Components of Para-Type
Wholly Aromatic Polyamide)
[0026] The following copolymer components may be used other than
the foregoing para-type aromatic diamine components and para-type
aromatic dicarboxylic acid components. Examples of aromatic
diamines as such copolymer components include benzene derivatives
(such as m-phenylenediamine, 2,4-diaminochlorobenzene,
2,6-diaminochlorobenzene, 2,4-diaminobromobenzene,
2,6-diaminobromobenzene, 2-amino-4-methoxyaniline, and
3-amino-4-methoxyaniline), 1,3-naphthylenediamine,
1,4-naphthylenediamine, 1,5-naphthylenediamine,
1,6-naphthylenediamine, 3,4'-diaminodiphenyl ether,
3,4'-diaminodiphenylketone, 3,4'-diaminodiphenylamine, and
3,4'-diaminodiphenylmethane. Examples of aromatic dicarboxylic acid
components as copolymer components include isophthalic acid
dichloride, 1,3-naphthalene dicarboxylic acid dichloride,
2,7-naphthalene dicarboxylic acid dichloride, 3,4'-biphenyl
dicarboxylic acid dichloride, and 3,4'-diphenyl ether dicarboxylic
acid dichloride. These copolymer components are contained in
preferably 20 mol % or less of the total dicarboxylic acid
component of the meta-type wholly aromatic polyamide because the
properties of the meta-type wholly aromatic polyamide tend to
deteriorate when the copolymerization ratio of these copolymer
components is too high. In referring to the non-crimped staple
fibers of the meta-type wholly aromatic polyamides, it is to be
understood that the "meta-" or "m-" notation may be appropriately
replaced with "para-" or "p-" in the wholly aromatic polyamides.
Such wholly aromatic polyamides also fall within the scope of the
invention of the organic resin non-crimped staple fiber according
to the present invention.
(Polyolefin)
[0027] The following describes use of polyolefin as a specific
example of the organic resin forming the non-crimped staple fiber
of the present invention. Preferred examples of the polyolefin used
as the organic resin in the present invention include isotactic
polypropylene, syndiotactic polypropylene, atactic polypropylene,
high-density polyethylene, medium-density polyethylene, linear
low-density polyethylene, low-density polyethylene,
ethylene-propylene random copolymerization polyolefin, and
polyethylene or polypropylene copolymerized with a third component
by block copolymerization or graft copolymerization. Examples of
the third component include vinyl acetate, vinyl chloride, styrene,
methyl acrylate, ethyl acrylate, isopropyl acrylate, methyl
methacrylate, ethyl methacrylate, isopropyl methacrylate, acrylic
acid, methacrylic acid, maleic acid, maleic acid anhydride, vinyl
chloride, vinylidene chloride, acrylonitrile, and acrylamide.
Particularly preferred is at least one polyolefin selected from the
group consisting of high-density polyethylene, an
ethylene-propylene random copolymer, polyethylene block or graft
copolymerized with maleic acid anhydride, and polypropylene block
copolymerized with maleic acid anhydride. More than one polyolefin
may be selected from these polyolefins, and used as a mixture.
[0028] Other than these organic resins, it is also possible to use
organic resins such as polyamide (e.g., nylon-6, and nylon-6,6),
polyoxymethylene, polyphenylene ether, polyphenylene sulfide,
cellulose, polysulfone, polyethersulfone, polycarbonate, and
polyallylate. These organic resins may be polyester compositions
containing known additives, for example, such as pigments, dyes,
flatting agents, stain-proofing agents, antimicrobial agents,
deodorants, fluorescent bleach, antioxidants, fire retardants,
stabilizers, UV absorbers, and lubricants. Taken together, the
non-crimped staple fiber in the organic resin non-crimped staple
fiber of the present invention is preferably any of organic resin
non-crimped staple fibers selected from a polyester non-crimped
staple fiber, a wholly aromatic polyamide non-crimped staple fiber,
and a polyolefin non-crimped staple fiber. In the organic resin
non-crimped staple fiber of the present invention, it is also
preferable that the non-crimped staple fiber is any of organic
resin non-crimped staple fibers selected from a polyethylene
terephthalate non-crimped staple fiber, a polytrimethylene
terephthalate non-crimped staple fiber, a polytetramethylene
terephthalate non-crimped staple fiber, a polyethylene naphthalate
non-crimped staple fiber, a polytrimethylene naphthalate
non-crimped staple fiber, a polytetramethylene naphthalate
non-crimped staple fiber, a meta-type wholly aromatic polyamide
non-crimped staple fiber, a para-type wholly aromatic polyamide
non-crimped staple fiber, a polyethylene non-crimped staple fiber,
and a polypropylene non-crimped staple fiber.
(Cross Sectional Shape and Configuration of Non-Crimped Staple
Fiber)
[0029] As an example of the shape of the transverse plane of the
organic resin non-crimped staple fiber of the present invention,
the fiber may be a solid fiber, a hollow fiber, or a conjugate
fiber, provided that the transverse plane orthogonal to the fiber
axial direction has a circular cross section at the circumference.
The shape of the fiber transverse plane is not limited to a
circular cross section, and may have an oval cross section, a
multi-lobed cross section such as a cross section with 3 to 8
lobes, or a modified cross section such as a triangular to
octangular polygonal cross section. As used herein, "fiber
transverse plane" means a fiber cross section taken at right angle
to the fiber axis. The fiber configuration is not limited to fibers
of a single organic resin. The non-crimped staple fiber of the
present invention may be a conjugate fiber configured from two or
more organic resins. The conjugate fiber may have a form of, for
example, a concentric sheath-core conjugate fiber, an eccentric
sheath-core conjugate fiber, a side-by-side conjugate fiber, an
island-in-the-sea conjugate fiber, and a segmented pie conjugate
fiber.
[0030] With the conjugate fiber configuration, the organic resin
non-crimped staple fiber of the present invention may be provided
as, for example, a fine fiber of 0.01 dtex or less, or a binder
fiber bonded to other fibers under heat and pressure.
[0031] Specific examples of the polyester-containing conjugate
fiber include sheath-core conjugate fibers in which polyalkylene
terephthalates such as polyethylene terephthalate, polytrimethylene
terephthalate, and polybutylene terephthalate, or polyalkylene
naphthalates such as polyethylene naphthalate, polytrimethylene
naphthalate, or polybutylene naphthalate are disposed as the core
component, and a copolymerized polyester or polyolefin is disposed
as the sheath component. The conjugate fiber also may be, for
example, an island-in-the-sea conjugate fiber in which a core
component organic resin such as above is disposed as the island
component, and a sheath component organic resin such as above is
disposed as the sea component. The conjugate fiber also may be, for
example, a side-by-side conjugate fiber or a segmented pie
conjugate fiber in which a core component organic resin such as
above, and a sheath component organic resin such as above are
separately disposed. Examples of the copolymer components of the
copolymerized polyester include one or more of the compounds, for
example, isophthalic acid, and polyethylene glycol, that can be
copolymerized with the polyester components above.
[0032] The polyolefin-containing conjugate fiber may be, for
example, a sheath-core conjugate fiber in which polypropylene (may
be any of the polypropylenes above) is disposed as the core
component, and polyethylene (may be any of the polyethylenes
above), a randomly copolymerized polyolefin of ethylene and
propylene, or copolymer polyethylene of polyethylene or
polypropylene copolymerized with a third component by block or
graft copolymerization is disposed as the sheath component. The
polyolefin-containing conjugate fiber also may be, for example, an
island-in-the-sea conjugate fiber in which an organic resin such as
the core components above is disposed as the island component, and
an organic resin such as the sheath components above is disposed as
the sea component. The polyolefin-containing conjugate fiber also
may be, for example, a side-by-side conjugate fiber or a segmented
pie conjugate fiber in which a core component organic resin such as
above, and a sheath component organic resin such as above are
separately disposed.
[0033] The non-crimped staple fiber of the present invention may be
an undrawn staple fiber or a drawn staple fiber. An undrawn staple
fiber is preferable for use as a binder fiber, which is bonded to
other fibers under heat and pressure using a calendar roller or the
like.
(Fineness, Fiber Length, and Crimp of Non-Crimped Staple Fiber)
[0034] The organic resin non-crimped ultrafine staple fiber of the
present invention has a single yarn fineness of 0.0001 to 0.6
decitex, preferably 0.007 to 0.55 decitex, more preferably 0.01 to
0.53 decitex. With a single yarn fineness of less than 0.0001
decitex, the staple fibers tend to seriously intertangle, and a
nonwoven fabric made from the non-crimped staple fiber of the
present invention may have a defective texture. Small single yarn
finenesses also cause difficulties in yarn making. Specifically,
small finenesses are not preferable as they cause breaking of yarn
or fluffing during yarn making, which makes it difficult to stably
produce fibers of desirable quality, and increases the cost of the
staple fiber. Another disadvantage of small single yarn finenesses
is that the increased contact area between the cutter and the fiber
increases the discharge resistance due to the fiber-metal friction
when cutting the fiber, and cause the blade to easily break, or
wear at the blade edge. However, an ultrafine non-crimped staple
fiber with a fineness as small as 0.0002 to 0.006 decitex, despite
the small single yarn fineness, has desirable properties such as
moisture permeability and waterproofing, odor adsorption, and the
efficiency for trapping microscopic objects, and can provide
desirable effects different from the effects of the staple fibers
of the foregoing fineness ranges, for example, in applications such
as abrasive cloths for magnetic discs, and separator or capacitor
papers for batteries. Staple fibers with such small finesses thus
also represent a preferred form of the present invention. On the
other hand, with a single yarn fineness exceeding 0.6 decitex, it
becomes difficult to exploit the advantages of the ultrafine fiber,
specifically the high nonwoven fabric strength, the high paper
strength, and the high density of the nonwoven fabric or the like
in a low basis weight region.
[0035] The organic resin non-crimped staple fiber of the present
invention has a fiber length of 0.01 to 5.0 millimeters, preferably
0.015 to 4.0 millimeters, more preferably 0.02 to 3.5 millimeters,
further preferably 1.0 to 3.3 millimeters. When the fiber length
exceeds 5.0 millimeters, the fibers tend to intertangle, and cause
defects. With a fiber length of less than 0.01 millimeters, the
aspect ratio as a ratio of fiber length to the width or the oblong
diameter of the fiber transverse plane becomes too small. This is
not preferable in terms of fiber binding in a nonwoven fabric, and
the strength of a nonwoven fabric. A fiber length may be selected
according to such factors as the intended use, and processability.
A staple fiber with the foregoing ultrafine finenesses and a fiber
length of 0.015 to 0.06 mm can be as effective as the ultrafine
staple fiber despite the stable fiber length, and such staple
fibers also represent a preferred form of the present
invention.
[0036] The staple fiber of the present invention needs to be
non-crimped, and there is no need to actively impart crimps. When
crimped, the staple fiber may not uniformly disperse upon being
dispersed in a dispersion medium, or a nonwoven fabric produced
from such staple fibers may not be able to have a low basis
weight.
(Cut-End Coefficient of Non-Crimped Staple Fiber)
[0037] The organic resin non-crimped staple fiber of the present
invention needs to have a cut-end coefficient of 1.00 to 1.40. The
cut-end coefficient represents the extent of cut-end defect as
defined in the present invention. The cut-end coefficient is
described below in detail with reference to FIG. 1, which
schematically represents an end portion of the non-crimped staple
fiber of the present invention. Referring to FIG. 1, the cut-end
coefficient is represented by b/a, where b is the maximum width
along a direction orthogonal to the fiber axis at the cut end
portion (or the maximum diameter when the cut end shape is circular
or substantially circular), and a is the thickness of a single yarn
(or the fiber diameter or fiber width of a single yarn) on the side
surface at the cut end of the non-crimped staple fiber magnified
with a light microscope. The cut-end coefficient is a measure of
the spread of the shape of the staple fiber at the cut end portion
relative to a normal single yarn thickness, and can be used as an
index of the appropriateness of the shape at the cut end portion. A
staple fiber with an index above 1.00 crushes under the pressure
exerted right angle to the fiber axis when cutting the fiber, and
has a large wide shape at the end. Such a wide shape is not a
simple expansion of the shape of the fiber transverse plane, but
can be described as a shape with no point symmetry. Specifically,
the large wide shape is often different from the shape of the fiber
transverse plane, and does not usually have a circular cross
section when the fiber transverse plane has a circular cross
section. The large wide shape also does not usually reflect the
modified cross section of the fiber transverse plane when the
transverse plane cross section is irregular in shape. When the
cut-end coefficient as an index of the fiber shape is 1.00 to 1.40,
the fiber can uniformly disperse in a dispersion medium, and
generation of aggregated clumps can be reduced even when the
cut-end has a shape different from the shape of the fiber
transverse plane itself of the single yarn fiber. The effects of
the present invention still can be obtained in this case. However,
an index above 1.40 makes the shape defective by making the maximum
width b of the large wide shape excessively large. A staple fiber
with such a defective cut-end shape has a terminal projection, and
becomes entangled with other staple fibers when dispersed in a
dispersion medium. Such tangles serve as the trapping points of
staple fibers having normal cut-ends, and often cause undispersed
clumps in the staple fibers in the dispersion medium. The
undispersed clumps lead to defective appearance or performance in a
nonwoven fabric or other such products produced with the
non-crimped staple fiber of the present invention. The proportion
of fibers with defective cut-ends thus needs to be reduced below
certain levels to reduce such defects. Studies by the present
inventors revealed that the defects can be reduced when the cut-end
coefficient ranges from 1.00 to 1.40, and that a cut-end
coefficient above 1.40 creates a cut-end projection, or a shape
that causes tangles. The present invention was completed on the
basis of these findings. A cut-end coefficient of 1.00 means that
the shape of the cut-end portion of the staple fiber and the shape
of the fiber transverse plane completely match in all non-crimped
staple fibers. The cut-end coefficient cannot take values below 1.0
with cutting methods that are generally considered practicable. The
cut-end coefficient was measured by observing the side surface at
the cut-end of randomly collected 50 non-crimped staple fibers with
a light microscope or a scanning electron microscope, using the
length measurement functionality of the microscope. The results
were averaged for evaluation. The fibers show desirable medium
dispersibility with no aggregated clumps when the cut-end
coefficient is 1.00 to 1.40, preferably 1.001 to 1.35, further
preferably 1.01 to 1.30. The most desirable state is when the
cut-end coefficient is 1.00, as mentioned above.
(Variation of Fiber Length of Non-Crimped Staple Fiber)
[0038] Fiber length variation needs to be reduced in the
non-crimped staple fiber of the present invention. Desirably, the
coefficient of variation relative to fiber length (the percentage
of the standard deviation relative to mean value) is 0.0% to 15.0%,
preferably 0.01% to 14.0%, more preferably 0.1% to 13.0% in a fiber
length measurement of randomly selected 50 non-crimped staple
fibers. With a large fiber length variation, fibers with large
aspect ratios (fiber length/fiber diameter) generate, and the
fibers become more likely to contact and become entangled with each
other upon being stirred in a dispersion medium. It is important to
reduce fiber length variation because this becomes more likely as
the fineness (fiber diameter) decreases. For the measurement of
coefficient of variation relative to fiber length, randomly
selected 50 staple fiber samples are placed on a cover glass, and
magnified with a light microscope or a scanning electron microscope
under the weight on the cover glass. The fiber lengths are then
measured in the magnified image using the length measurement
functionality of the light microscope or scanning electron
microscope, and the mean value and the standard deviation are
calculated. The ratio of standard deviation to mean value is then
calculated to determine the coefficient of variation relative to
fiber length. The non-crimped staple fiber of the present invention
is preferably a drawn yarn. With a drawn yarn, a wet-laid nonwoven
fabric or other such products made from the non-crimped staple
fiber of the present invention can have a sufficient tensile
strength, or other strengths necessary as a nonwoven fabric.
(Moisture Content of Non-Crimped Staple Fiber)
[0039] The non-crimped staple fiber of the present invention needs
to have a moisture content of 10 to 200 weight %. A moisture
content of less than 10 weight % is not preferable because it makes
it difficult for the staple fibers to form a bundle, and tends to
increase the cut-end coefficient or the variation coefficient of
fiber length. On the other hand, a moisture content above 200
weight % is not preferable because it causes a large amount of
water to become removed from the fiber tow, and may interfere with
the ease of handling of the fiber bundle in the cutting process.
Preferably, moisture is imparted before the cutting process in
staple fiber production. The moisture content can be adjusted by
imparting water with an oiling roller when the desired moisture
content is toward the lower end of the foregoing range, or with nip
rollers by which the fibers dipped in water are held and squeezed
when the desired moisture content is toward the upper end of the
foregoing range. When even smaller moisture contents are needed,
water may be imparted by spraying. When spraying water, water may
be imparted after the cutting process. The moisture content is
preferably 12 to 150 weight %, more preferably 13 to 120 weight %,
further preferably 16 to 100 weight %.
(Producing Process of Organic Resin Non-Crimped Staple Fiber)
[0040] The organic resin non-crimped staple fiber of the present
invention above may be produced by using, for example, the
following processes.
(Producing Process of Polyester Non-Crimped Staple Fiber)
[0041] A process for producing the polyester non-crimped staple
fiber is described first. A polyester polymer is melted, ejected
through a spinneret of known spinning equipment, and taken up at a
rate of 100 to 2000 m/min while being cooled with cooled air to
obtain an undrawn yarn. The undrawn yarn is drawn in 70 to
100.degree. C. hot water or in a 100 to 125.degree. C. steam, and
an oil is imparted to obtain a drawn yarn. The drawn yarn is then
subjected to drying, and, as required, a relaxation heat treatment
to obtain a fiber bundle, which is then cut into a fiber length of
0.01 to 5.0 millimeters to obtain a non-crimped staple fiber.
[0042] Preferably, water is imparted to the fiber bundle before
cutting the fiber bundle, as described above. The method of
imparting water to the fiber bundle is not particularly limited,
and water may be imparted by using, for example, a spray method, an
oiling roller method, or a dipping method, after the relaxation
heat treatment and before feeding the fiber bundle to the cutter.
The oiling roller method is preferred in terms of uniformly
imparting moisture in the foregoing ranges. When using a spray
method or an oiling roller method, water should be imparted from
the both sides of the fiber bundle to uniformly impart water to the
fiber bundle.
[0043] The method for cutting the fiber bundle into a predetermined
fiber length is not particularly limited. However, when a
guillotine fiber-bundle cutter device is used to cut fibers of fine
single yarns, the fibers easily bend or buckle, and the cutting
blade may not contact the fibers at right angle, producing
obliquely cut fibers, or fibers of different lengths. Such
nonuniformity is believed to be due to the cutting method of the
guillotine fiber-bundle cutter device, whereby a fiber bundle is
pushed for the predetermined cut length toward the shear blades
composed of a fixed blade and a movable blade. This may not be
desirable as it increases the cut-end coefficient or the
coefficient of variation relative to fiber length (fiber length
variation) of the present invention.
[0044] When using a guillotine fiber-bundle cutter device, movement
of the fiber bundle should thus be restricted while cutting the
fibers so that the fiber bundle does not bend or buckle under its
weight or under the pressure of the cutter blade. Typically, fiber
bundles are restricted by being wrapped in a sheet-like material.
It is, however, not always possible to sufficiently restrict
movement of the fiber bundle with a method that wraps the fiber
bundle in, for example, paper. In a more preferred method, the
fiber bundle is dipped in water, and frozen after being degassed to
make an ice pillar and fix the fiber bundle. The fiber bundle is
then cut in the ice pillar with a guillotine cutter, and the ice
(water) is removed. This method involves less fiber displacement,
and makes the coefficient of variation relative to fiber length
(fiber length variation) desirable to prevent the cut-end defect.
The ice pillar may be replaced by a dry ice pillar.
[0045] Another method to cut a fiber bundle into a predetermined
length uses an Eastman or other such rotary cutters with multiple
cutter blades that are radially disposed outwardly at regular
intervals. In this method, a fiber bundle is rolled onto the rotary
cutter blades, and is continuously cut into a predetermined length
while being pressed against the cutting blades. This cutting method
has limitations in the cutter blade intervals with which the cut
non-crimped staple fibers can be discharged. The method is
nonetheless preferable because of the advantage that the cut-end
defect or the fiber length variation due to single yarn
displacement can be reduced by applying a moderate tension to the
fiber bundle with the constituent single yarns being uniformly
aligned without a slack before feeding the fiber bundle to the
rotary cutter device. However, the method involves problems
intrinsic to the device structure, including the large discharge
resistance of the cut fibers, and breaking of the cutter blade. The
discharge resistance can be reduced by providing a large space for
the cut fibers in the device structure, whereas breaking of the
cutter blade can be prevented by reducing the fiber-metal friction
with a diamond-like coating applied to the cutter blade surface. In
this way, a fiber with the desired fiber length of 5.0 millimeters
or less, or a shorter fiber of a 3.0 millimeters or less can be
stably obtained.
[0046] The rotary cutter device typically includes cutter blades,
and feed rollers for supplying a fiber bundle to the cutter blade.
Desirably, the draft rate of the rotary cutter and the feed rollers
[(circumferential velocity of rotary cutter)/(circumferential
velocity of feed rollers)] is set to 1.01 to 1.05. With a draft
rate of less than 1.01, the tension created in the single yarn
fibers of the fiber bundle tends to vary when cutting long fibers,
and variation often occurs in the fiber length of the resulting
staple fibers. A draft rate above 1.05 is not preferable because it
has the possibility of mechanically stretching the fiber itself,
and altering the physical properties of the fiber. Specifically,
when using a rotary cutter device, a staple fiber with a
coefficient of variation relative to fiber length of 0.0 to 15.0%
can be obtained by setting the draft ratio as above. Desirably, the
fiber bundle is cut by being pressed with pressure rollers
installed at a certain clearance between the rollers and the edge
of the cutter blade of the rotary cutter. By being cut under the
gradually applied pressure of the pressure rollers, the cut fibers
experience less resistance as they pass between the cutter blades,
and can have less deformation at the cut-end. Further, with the
pressure applied to the edge of the cutter blade at a certain
clearance between the rollers and the edge, the amount of the fiber
bundle rolled onto the rotary cutter can remain constant during a
continuous operation. The fiber bundle at the outermost periphery
becomes relaxed in fiber direction as it approaches the rotor
center, and is cut upon contacting the cutter blade. Here, any
fluctuation in the roll amount of the fiber bundle leads to
variation of the extent of relaxation, and varies the fiber
length.
(Producing Process of Meta-Type Wholly Aromatic Polyamide
Non-Crimped Staple Fiber)
[0047] The following describes a process for producing the wholly
aromatic polyamide non-crimped staple fiber. The process will be
described through the case of a meta-type wholly aromatic polyamide
staple fiber as a specific example of the wholly aromatic polyamide
staple fiber of the present invention. The process is described in
steps, which include a meta-type wholly aromatic polyamide
producing step, a spinning solution preparation step, a spinning
and coagulation step, a plasticization draw bath drawing step, a
washing step, a saturated water vapor treatment step, a dry heat
treatment step, and a cutting step.
[Meta-Type Wholly Aromatic Polyamide Producing Step]
[0048] The meta-type wholly aromatic polyamide producing process is
not particularly limited, and processes such as solution
polymerization and interface polymerization may be used that use,
for example, a meta-type aromatic diamine component and a meta-type
aromatic dicarboxylic acid dichloride component as raw materials.
For example, m-phenylenediamine and isophthalic acid dichloride may
be used as raw materials. The degree of polymerization of the
meta-type wholly aromatic polyamide should be 1.3 to 3.0 dL/g in
terms of an inherent viscosity (IV) as measured by using 30.degree.
C. concentrated sulfuric acid as solvent.
[Spinning Solution Preparation Step]
[0049] A typical example of the producing process of the meta-type
wholly aromatic polyamide non-crimped staple fiber used in the
present invention is described below. First, a long fiber is
produced in the steps described below. The long fiber is then fed
to the cutting step to obtain the meta-type wholly aromatic
polyamide staple fiber.
[0050] In the spinning solution preparation step, the meta-type
wholly aromatic polyamide is dissolved in an amide solvent to
prepare a spinning solution (meta-type wholly aromatic polyamide
polymer solution). The spinning solution is typically prepared with
an amide solvent. Examples of the amide solvent include
N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), and
dimethylacetoamide (DMAc). Preferred for solubility and safety of
handling are NMP and DMAc. The concentration of the spinning
solution may be appropriately selected taking into consideration
the coagulation rate, and the solubility of the meta-type wholly
aromatic polyamide in the next spinning and coagulation step.
Typically, the concentration is preferably, for example, 10 to 30
mass % when the meta-type wholly aromatic polyamide is poly
m-phenylene isophthalamide, and the solvent is NMP.
[Spinning and Coagulation Step]
[0051] In the spinning and coagulation step, the spinning solution
(meta-type wholly aromatic polyamide polymer solution) obtained
above is spun into a coagulation solution to coagulate, and a
porous fiber material is obtained. The spinning device is not
particularly limited, and a known wet spinning device may be used.
Conditions such as the number of spinning holes in the spinneret,
the hole arrangement, and the hole shape are not particularly
limited, as long as the solution can be stably wet spun. For
example, a multi-hole spinneret for staple fibers (short fibers)
with 500 to 30,000 holes, and a spinning hole diameter of 0.05 to
0.2 millimeters may be used. The temperature of the spinning
solution (meta-type wholly aromatic polyamide polymer solution)
spun out of the spinneret should be 10 to 90.degree. C. The
coagulation bath is configured as a two-component aqueous solution
of substantially amide solvent and water. The amide solvent in the
coagulation bath composition is not particularly limited, as long
as it can dissolve the meta-type wholly aromatic polyamide, and is
desirably miscible with water. Preferred examples include
N-methyl-2-pyrrolidone, dimethylacetoamide, dimethylformamide, and
dimethylimidazolidinone (e.g., 1,3-dimethyl-2-imidazolidinone). The
mixing ratio (weight ratio) of the amide solvent to water is
preferably 10/90 to 90/10, more preferably 30/70 to 70/30.
[0052] As required, an inorganic sodium salt, a potassium salt, a
magnesium salt, or a calcium salt may be dissolved in the
coagulation bath in 0.1 to 8.0 weight %.
[Plasticization Draw Bath Drawing Step]
[0053] In the plasticization draw bath drawing step, the fiber
bundle is drawn in a plasticization draw bath while the porous
fiber (yarn) bundle obtained after the coagulation in the
coagulation bath is in a plastic state. The plasticization draw
bath used to obtain the fiber used in the present invention is
prepared from an aqueous solution containing an amide solvent, and
is substantially salt free. The amide solvent is not particularly
limited, as long as it can swell the meta-type wholly aromatic
polyamide, and is desirably miscible with water. Examples of the
amide solvent include N-methyl-2-pyrrolidone, dimethylacetoamide,
dimethylformamide, and dimethylimidazolidinone.
[0054] The temperature and the composition of the plasticization
draw bath are closely related to each other. Preferably, the
plasticization draw bath contains 20 to 70 mass % of the amide
solvent, and has a temperature of 20 to 70.degree. C. When the mass
concentration of the amide solvent, or the temperature is below
these ranges, the porous fiber material does not sufficiently
plasticize, and it becomes difficult to ensure a sufficient draw
ratio in the plasticization drawing.
[0055] On the other hand, when the mass concentration of the amide
solvent, or the temperature is above the foregoing ranges, the
porous fiber surface melts and fuses, and makes it difficult to
desirably make yarns.
[0056] In obtaining the fiber used in the present invention, the
draw ratio in the plasticization draw bath is preferably 1.5 to 10,
more preferably 2.0 to 6.0. With a draw ratio of less than 1.5, the
resulting fiber suffers from poor mechanical characteristics (e.g.,
strength, and modulus), and it may become difficult to provide the
necessary break strength for the nonwoven fabric or other such
products produced with the fiber of the present invention. It also
becomes difficult to promote sufficient removal of the solvent from
the porous fiber material, making it difficult to produce a fiber
with 1.0 mass % or less of residual solvent.
[Washing Step]
[0057] In the washing step, the fiber from the plasticization draw
bath drawing step is sufficiently washed with water. Preferably,
washing is performed in stages to avoid adverse effects on fiber
quality. Particularly, the temperature of the washing bath, and the
concentration of the amide solvent in the washing bath in the
washing step have effects on the state of the amide solvent
extracted from the fiber, and the state of water entering the fiber
from the washing bath. In order to optimize these states, it is
preferable to perform the washing step in stages, and control the
temperature condition, and the concentration condition of the amide
solvent.
[Saturated Water Vapor Treatment Step]
[0058] In the saturated water vapor treatment step, the fiber
washed in the washing step is subjected to a heat treatment in a
saturated water vapor. The saturated water vapor treatment enables
improving alignment while reducing fiber crystallization. The heat
treatment in a saturated water vapor atmosphere allows the heat to
more uniformly reach inside the fiber bundle than in a dry heat
treatment, and enables producing a more uniform fiber. The draw
ratio in the saturated water vapor treatment step is also closely
related to development of fiber strength. Any draw ratio may be
chosen, taking into account the required physical properties of the
product. In the present invention, the draw ratio is 0.7 to 5.0,
preferably 1.1 to 2.0. A draw ratio below 0.7 is not preferable as
it lowers the cohesion of the fiber bundle (yarn) in a saturated
water vapor atmosphere. On the other hand, a draw ratio above 5.0
is not preferable as it increases the occurrence of single yarn
breakage during the draw, and generates a fluff or broken yarns.
Preferably, the saturated water vapor treatment is performed for
0.5 to 5.0 seconds. When continuously treating the running fiber
bundle, the most effective treatment time should be selected by
appropriately adjusting factors that determine the treatment time,
specifically the running distance and the running speed of the
fiber bundle in a water vapor treatment vessel.
[Dry Heat Treatment Step]
[0059] In the dry heat treatment step, the fiber from the saturated
water vapor treatment step is subjected to a dry heat treatment.
The dry heat treatment method is not particularly limited, and may
be, for example, a method that uses a hot plate, a heat roller, or
the like. After the dry heat treatment, a long fiber of meta-type
wholly aromatic polyamide can be finally obtained. The heat
treatment temperature of the dry heat treatment step preferably
ranges from 250 to 400.degree. C., more preferably 300 to
380.degree. C. When the dry heat treatment temperature is less than
250.degree. C., the porous fiber cannot be sufficiently densified,
and the mechanical characteristics of the fiber become
insufficient. On the other hand, a dry heat treatment temperature
above 400.degree. C. is not preferable because it causes heat
deterioration on fiber surface, and lowers quality.
[0060] The draw ratio in the dry heat treatment step is closely
related to development of fiber strength. Any draw ratio may be
chosen according to the strength or other required properties of
the fiber. The draw ratio in the dry heat treatment step is
preferably 0.7 to 4.0, more preferably 1.5 to 3.0. When the draw
ratio is less than 0.7, the step tension decreases, and the fiber
suffers from poor mechanical characteristics. On the other hand,
when the draw ratio is above 4.0, the single yarn becomes more
likely to break while being drawn, and generates a fluff or broken
yarns. As used herein, "draw ratio" is the ratio of the treated
fiber length to the undrawn fiber length, as with the case of the
draw rate described in conjunction with the saturated water vapor
treatment step. For example, a draw ratio of 0.7 means that the
fiber becomes 70% of the original length after it restrictively
shrinks in the dry heat treatment step. A draw ratio of 1.0 means a
fixed-length heat treatment. The process time of the dry heat
treatment step is preferably 1.0 to 45 seconds. The treatment time
may be adjusted according to the running speed of the fiber bundle,
and the contact length with a hot plate, a heat roller, or the
like.
[Cutting Step]
[0061] In the production of the wholly aromatic polyamide
non-crimped staple fiber of the present invention, the meta-type
wholly aromatic polyamide long fiber after the dry heat treatment
is cut into a predetermined length in a cutting step. The method
used to cut the fiber into a predetermined length is not
particularly limited. However, considerations need to be given with
regard to use of a guillotine fiber-bundle cutter device that
includes shear blades composed of a fixed blade and a movable
blade, and in which a fiber bundle is pushed for a predetermined
cut length toward the shear blades. Specifically, when cutting
fibers of fine single yarns, the fibers easily bend or buckle, and
the cutting blade may not contact the fibers at right angle,
producing obliquely cut fibers, or fibers of different lengths.
This may not be appropriate as it increases the cut-end
coefficient, or the coefficient of variation relative to fiber
length (fiber length variation) of the present invention. By
performing the cutting procedure in the same manner as in the
production of the polyester non-crimped staple fiber with care
being given to the considerations described therein, a staple fiber
of predetermined physical properties can be obtained also for the
meta-type wholly aromatic polyamide non-crimped fiber.
[0062] In the steps from the meta-type wholly aromatic polyamide
producing step to the cutting step, it is to be understood that the
"meta-" or "m-" notation may be appropriately replaced with "para-"
or "p-", and that the foregoing steps also represent the process
for producing the organic resin non-crimped staple fiber of the
present invention made from such corresponding para-type wholly
aromatic polyamides.
(Producing Process of Polyolefin Non-Crimped Staple Fiber)
[0063] A process for producing the polyolefin non-crimped staple
fiber is described below. In the polyolefin non-crimped staple
fiber producing process, the polyester used as the organic resin in
the polyester non-crimped staple fiber producing process is
replaced with a desired polyolefin. The desired polyolefin
non-crimped staple fiber can be produced by melt-spinning the
selected polyolefin under the common melt-spinning conditions after
replacing some of or all of these conditions with the conditions
used in the polyester non-crimped staple fiber producing process
above.
(Moisture Content in Cutting Step, and Effects of the
Invention)
[0064] The moisture content of the fiber bundle fed to the rotary
cutter is desirably 10 to 200% in the non-crimped staple fiber of
any organic resin, whether it is a polyester, a wholly aromatic
polyamide, or a polyolefin, as described above. The fibers in a
fiber bundle with a moisture content of 10% or more bind together,
and the fiber bundle uniformly contacts the cutter blade at right
angle when being cut. The fibers thus contact the cutter blade
under uniform pressure while being cut. This improves the cut-end
coefficient, and the coefficient of variation relative to fiber
length. The resulting staple fibers with the desirable cut-end
coefficient and the desirable coefficient of variation relative to
fiber length are thus less likely to include fibers of large aspect
ratios. The fibers are thus less likely to be entangled with each
other, and can uniformly disperse in a medium without causing
aggregation defects. On the other hand, a moisture content above
200% causes a large amount of water to become removed from the tow,
or the fibers in a fiber bundle state, and may interfere with the
ease of handling. The moisture content should therefore be at most
200%. By confining the moisture content of the fiber bundle in the
fiber cutting step in the foregoing range, the moisture content of
the product organic resin non-crimped staple fiber can also fall in
the foregoing range. The surface of the organic resin non-crimped
staple fiber may be treated with a surface treatment agent such as
a dispersant, a lightfast agent, a smoothing agent, an adhesive, or
a mixture of these, provided that such a surface treatment is not
detrimental to the effects of the present invention. When the
non-crimped staple fiber is a polyester non-crimped staple fiber or
a polyolefin non-crimped staple fiber, it is preferable to impart a
polyester-polyether copolymer that is compatible with both the
organic resin and the dispersion medium.
INDUSTRIAL APPLICABILITY
[0065] The organic resin non-crimped staple fiber of the present
invention can uniformly disperse in a dispersion medium, and can
reduce generation of aggregated clumps in applications such as
wet-laid nonwoven fabrics, and staple fiber reinforced resins. The
staple fibers in a nonwoven fabric or other such products made from
the non-crimped staple fiber are also uniformly dispersed. The
product nonwoven fabric is thus free from defects such as
microscopic nonuniform dispersion of staple fibers, and variation
of basis weight and thickness, and can have desirable properties
such as uniform breathability and liquid permeability. The final
product produced by processing such nonwoven fabrics involves few
defects, and can have physical properties with improved reliability
(reliable product warranty). The yield of the interim product
(e.g., nonwoven fabric, and resin molded body) also can improve.
The present invention is thus also highly advantageous in terms of
resource saving and economy.
EXAMPLES
[0066] The following describes the configurations and the effects
of the present invention in detail using Examples. The present
invention, however, is in no way limited by the following Examples.
In the following, "part" means "weight part", unless otherwise
stated. The values of various physical properties in Examples and
Comparative Examples were measured according to the following
methods.
(1) Inherent Viscosity: [.eta.]
[0067] For the polyester fiber, 0.12 g of a fiber (polymer) sample
was dissolved in 10 mL of a tetrachloroethane/phenol mixed solvent
(volume ratio 1/1), and measured for inherent viscosity (dL/g) at
35.degree. C. For the wholly aromatic polyamide fiber, the fiber
(polymer) was dissolved in 97 mass % concentrated sulfuric acid,
and measured for inherent viscosity (dL/g) at 30.degree. C. with an
Ostwald viscometer.
(2) Melt Flow Rate: MFR
[0068] Melt flow rate was measured according to condition 4 of JIS
K 7210 (measurement temperature 190.degree. C., load 21.18N). The
melt flow rate is a measured value of a polymer pellet sample
immediately before melt-spinning.
(3) Melting Point: Tm
[0069] The TA Instruments product TA-2920 differential scanning
calorimeter DSC was used. For the measurement, a polymer sample (10
mg) was heated from room temperature to 260.degree. C. at
10.degree. C./min in a nitrogen atmosphere. The melting point was
defined as the peak temperature at the crystal melting endothermic
peak.
(4) Single Yarn Fineness
[0070] Single yarn fineness was measured by using the method
described in JIS L 1015:2005 8.5.1, method A. Specifically, the
following measurement technique was used. A small amount of a fiber
sample was combed parallel to each other with a metal comb, and put
on flock paper placed on a cutting board. With a gauge plate
pressed against the fiber sample being pulled straight with a
moderate force, the fiber sample was cut into a 30-mm length with
the blade of a safety razor or the like. The fibers were counted,
and a set of 300 fibers was weighed to determine apparent fineness.
The actual fineness was calculated from the apparent fineness and
the separately measured equilibrium moisture content, using the
following equation. The actual fineness was calculated five times,
and the mean value was determined.
F=[(100+R0)/(100+Rc)].times.D
[0071] F: Actual fineness
[0072] D: Apparent fineness
[0073] R0: Formal moisture content (%) (value specified by JIS L
0105 4.1)
[0074] Rc: Equilibrium moisture content (%)
(5) Cut-End Coefficient
[0075] Fifty non-crimped staple fibers were randomly picked up, and
placed on a cover glass. The fibers were observed with a light
microscope or a scanning electron microscope under the weight of
the cover glass. The fibers were then measured for maximum diameter
b at the cut-end, and fiber diameter a of a single yarn (see FIG.
1), using the length measurement functionality of the light
microscope or scanning electron microscope. The cut-end coefficient
was calculated as follows.
Cut-end coefficient=b/a
[0076] The mean value of the measured values of each fiber was used
for the evaluation of cut-end coefficient.
(6) Coefficient of Variation Relative to Fiber Length
[0077] Fifty non-crimped staple fibers were randomly picked up, and
placed on a cover glass. The fibers were observed with a light
microscope or a scanning electron microscope under the weight of
the cover glass. The fiber length was then measured using the
length measurement functionality of the light microscope or
scanning electron microscope. After determining the mean value and
the standard deviation, the coefficient of variation relative to
fiber length (CV %) was calculated as follows.
Coefficient of variation relative to fiber length(CV %)=(standard
deviation of fiber length)/(mean value of fiber
length).times.100(%)
(7) Moisture Content
[0078] About 100 g of fibers with moisture were bone-dried in a
120.degree. C. hot-air circulation drier. Moisture content was
determined from the weight W0 of the sample before drying, and the
weight W1 of the sample after drying, as follows.
Moisture content (%)=[(W0-W1)/W1].times.100
(8) Water Dispersibility
[0079] The dispersibility of fibers in water was evaluated to
determine the presence or absence of a fiber aggregation defect due
to cut-end and fiber length. Soft water (500 cc) was placed in a
1000-cc beaker, and fibers (0.5 g) that had been cut into a
predetermined fiber length were put in the beaker, and stirred with
a magnetic stirrer (stirrer) at ordinary temperature for 20 min.
The fibers were filtered through a 0.15 mm-mesh metal net, and the
number of fiber clumps with a size of 1 mm.sup.2 or more remaining
on the metal net was counted. The results are represented as Good
when the number of fiber clumps was 3 or less, Acceptable when 3 to
5 fiber clumps were observed, and Poor when there were 5 or more
fiber clumps.
Example 1
[0080] A polyethylene terephthalate (PET) chip with an inherent
viscosity of 0.64 dL/g containing 0.3 weight % of titanium dioxide
was melted at 290.degree. C., ejected through a spinneret having
3000 round holes at an ejection rate of 450 g/min, and taken up at
a rate of 1320 m/min to obtain polyethylene terephthalate undrawn
yarns having a single yarn fineness of 1.14 decitex. The undrawn
yarns were aligned, and a tow of 140000 decitex was obtained. The
tow was drawn in two stages in hot water at a total draw ratio of
2.51, and a polyester-polyether copolymer was imparted in 0.3
weight % of the polyester fiber weight. After imparting the
polyester-polyether copolymer, the yarns were dried, and heat set
at 120.degree. C. in a relaxed state to obtain an uncrimped drawn
polyethylene terephthalate fiber bundle having a single yarn
fineness of 0.51 decitex. Water was imparted to the drawn
polyethylene terephthalate fiber bundle with an oiling roller to
make the moisture content 15%, and the fibers were cut into staple
fibers with a fiber length of 3.0 millimeters, using an Eastman
rotary cutter fiber cutting device with a blade interval of 3.0
millimeters. The fibers were cut with a draft rate of 1.02 between
the rotary cutter and feed rollers under the pressure of a pressure
roller pressing the fiber bundle against the cutter blade. Table 1
shows the evaluation results, including the fineness, the moisture
content, the cut-end coefficient, the coefficient of variation
relative to fiber length, and the water dispersibility of the
polyester non-crimped staple fiber.
Example 2
[0081] The same procedures used in Example 1 were performed to
obtain a non-crimped staple fiber, except that the fiber was cut
into a staple fiber with a fiber length of 1.5 millimeters. The
evaluation results for the polyester non-crimped staple fiber are
presented in Table 1.
Example 3
[0082] The non-crimped drawn polyethylene terephthalate fiber
bundle obtained in Example 1 was dipped in water, and held and
squeezed with nip rollers to make the moisture content 30%. Four of
the fiber bundles prepared in this fashion were disposed side by
side to make a fiber bundle. The fiber bundle was dipped in a
cylindrical container that had been charged with boiled processing
water, and frozen at an atmospheric temperature of -12.degree. C.
over the course of 15 h to obtain a fiber bundle contained in ice.
The fiber bundle in ice was then cut into a fiber length of 1.5
millimeters using a known guillotine fiber-bundle cutter device
(Onouchi Seisakusho, Model: D100) that had been adjusted to make
this fiber length. The polyester non-crimped staple fiber was
evaluated after being thawed. The results are presented in Table 1.
The notation "ice pillar+guillotine" used in Tables 1 and 3 refers
to the fiber bundles of Examples 3 to 5 that were cut in ice with a
guillotine cutter.
Example 4
[0083] An ultrafine long fiber bundle was produced from an
island-in-the-sea conjugate fiber by using the following
procedures. Polyethylene terephthalate with a melt viscosity of 120
Pasec at 285.degree. C. was used as the island component. As the
sea component, altered copolymerized polyethylene terephthalate
with a 285.degree. C. melt viscosity of 135 Pasec was used that was
prepared by copolymerizing 4 weight % of polyethylene glycol having
a number average molecular weight of 4000, and 9 mol % of 5-sodium
sulfoisophthalic acid. The fiber was melt-spun at a spinning speed
of 1500 m/min to obtain an ultrafine fiber precursor fiber
(island-in-the-sea conjugate fiber) that was drawn 3.9 times, using
a spinneret designed to produce a conjugate fiber containing 400
islands in a sea component:island component weight ratio of 30:70.
The drawn ultrafine fiber precursor fibers were bundled together to
obtain a fiber bundle of 500000 decitex, and dipped and passed
through a 75.degree. C., 4 weight % sodium hydroxide aqueous
solution at such a rate that the fibers were in the solution for 15
min. This produced an ultrafine long fiber bundle (single yarn
fiber diameter of 750 nanometers, 0.0056 decitex) that was 27.6
weight % less than the fiber bundle of the ultrafine fiber
precursor fibers.
[0084] The ultrafine long fiber bundle was dipped in water, and
held and squeezed with nip rollers to make the moisture content
100%. Four of the fiber bundles prepared in this fashion were
disposed side by side to make a fiber bundle. The fiber bundle was
dipped in a cylindrical container that had been charged with boiled
processing water, and frozen at an atmospheric temperature of
-12.degree. C. over the course of 15 h to obtain a fiber bundle
contained in ice. The fiber bundle in ice was then cut into a fiber
length of 0.05 millimeters using a known guillotine fiber-bundle
cutter device (Onouchi Seisakusho, Model: D100) that had been
adjusted to make this fiber length. The polyester non-crimped
staple fiber was evaluated after being thawed. The results are
presented in Table 1.
Example 5
[0085] The same procedures used in Example 4 were performed, except
that a spinneret designed to produce 1500 islands was used, and
that the fibers were spun, drawn, and cut to produce a fiber bundle
with a single yarn fineness of 0.0004 decitex (fiber diameter of
200 nanometers), and a fiber length of 0.02 millimeters. The
evaluation results for the polyester non-crimped staple fiber are
presented in Table 1.
TABLE-US-00001 TABLE 1 Unit Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Fiber
configuration -- Single component Single component Single Component
Island-in-sea conjugate Island-in-sea conjugate fiber fiber fiber
fiber fiber Organic resin -- PET PET PET Island component: PET,
Island component: PET, Sea component: Sea component: Copolymerized
PET Copolymerized PET Cutting method -- Rotary cutter Rotary cutter
Ice pillar + guillotine Ice pillar + guillotine Ice pillar +
guillotine Fineness dtex 0.51 0.51 0.51 0.0056 0.0004 Fiber length
mm 3.0 1.5 1.5 0.05 0.02 Moisture content weight % 15 15 30 100 100
Cut-end coefficient -- 1.02 1.03 1.20 1.30 1.30 coefficient of
variation % 2.4 3.3 8.0 10.0 12.0 relative to fiber length Water
dispersibility -- Good Good Good Good Good
Comparative Example 1
[0086] Ten of the non-crimped drawn polyethylene terephthalate
fiber bundles obtained in Example 1 were bundled to obtain a fiber
bundle of 1400000 decitex. The fiber bundle was then wrapped in
paper. The wrapped fiber bundle was cut into a fiber length of 3.0
millimeters to obtain a non-crimped staple fiber, using a known
guillotine fiber-bundle cutter device (Onouchi Seisakusho, Model:
D100) that had been adjusted to make this fiber length. The
evaluation results for the polyester non-crimped staple fiber are
presented in Table 2.
Comparative Example 2
[0087] The same procedures used in Comparative Example 1 were
performed to obtain a non-crimped staple fiber, except that the
fiber bundle was cut into a staple fiber with a fiber length of 1.5
millimeters. The evaluation results for the polyester non-crimped
staple fiber are presented in Table 2.
Comparative Example 3
[0088] The same procedures used in Comparative Example 1 were
performed to obtain a non-crimped staple fiber, except that the
draft rate between the rotary cutter and the feed rollers was set
to 0.98. The evaluation results for the polyester non-crimped
staple fiber are presented in Table 2.
TABLE-US-00002 TABLE 2 Unit Com. Ex. 1 Com. Ex. 2 Com. Ex. 3 Fiber
configuration -- Single component Single component Single component
fiber fiber fiber Organic resin -- PET PET PET Cutting method --
Guillotine Guillotine Rotary cutter Fineness dtex 0.51 0.51 0.51
Fiber length mm 3.0 1.5 3.0 Moisture content weight % 15 15 15
Cut-end coefficient -- 1.50 1.60 1.02 coefficient of variation %
50.0 80.0 18.0 relative to fiber length Water dispersibility --
Poor Poor Acceptable
Example 6
Spinning Solution Preparation Step
[0089] A reaction vessel equipped with a thermometer, an agitator,
and a raw material inlet was charged with 815 parts of
N-methyl-2-pyrrolidone (hereinafter, "NMP") that had been
dehydrated with molecular sieves. Thereafter, 108 parts of
m-phenylenediamine was dissolved into the NMP, and the mixture was
cooled to 0.degree. C. For reaction, 203 parts of isophthalic acid
chloride that had been purified by distillation, and pulverized in
a nitrogen atmosphere was added to the cooled m-phenylenediamine
solution while being stirred. The reaction temperature increased to
about 50.degree. C., and the mixture was kept stirred at this
temperature for 60 min. The reaction was further allowed for 60 min
under the applied heat of 60.degree. C.
[0090] After the reaction, calcium hydroxide (70 parts) was added
to the polymer solution in fine powdery form, and dissolved for
neutralization over the course of 60 min (first neutralization).
Four parts of the remaining calcium hydroxide was dispersed in 83
parts of NMP to prepare a slurry, and the slurry (neutralizer) was
added to the neutralized polymer solution while being stirred
(second neutralization). The second neutralization was performed at
40 to 60.degree. C. with stirring for about 60 min to prepare a
polymer solution (spinning solution) in which the calcium hydroxide
was completely dissolved.
[0091] The polymer solution (spinning solution) had a polymer
concentration of 14 (in terms of weight parts of the polymer with
respect to the total 100 weight parts of the polymer and the NMP),
and the resultant poly m-phenylene isophthalamide polymer had an
inherent viscosity (IV) of 2.37 dL/g. The polymer solution
(spinning solution) had a calcium chloride concentration of 46.6
parts, and a water concentration of 15.1 parts with respect to 100
parts of the polymer.
[Spinning and Coagulation Step]
[0092] The spinning solution prepared in the spinning solution
preparation step was ejected and spun into a 40.degree. C.
coagulation bath through a spinneret having 500 holes with a hole
diameter of 0.07 millimeters. The coagulation solution had a
composition with a water:NMP:calcium chloride mass ratio of
48:48:4, and was passed through the coagulation bath over a dip
length (effective coagulation bath length) of 70 cm at a yarn rate
of 5 m/min. The porous fiber material after the coagulation in the
coagulation bath had a density of 0.71 g/cm.sup.3.
[Plasticization Draw Bath Drawing Step]
[0093] The fiber bundle was drawn in a plasticization draw bath at
a draw ratio of 3.0. The plasticization draw bath had a composition
with a water:NMP:calcium chloride mass ratio of 44:54:2, and a
temperature of 40.degree. C.
[Washing Step]
[0094] The plasticized and drawn fiber bundle was thoroughly washed
first with 30.degree. C. cold water, and then with 60.degree. C.
hot water. The cold water and the hot water were checked for
sufficiently lowered levels of amide solvent concentration after
the washing.
[Saturated Water Vapor Treatment Step]
[0095] The fibers were then subjected to a saturated water vapor
heat treatment at a draw ratio of 1.1 in a container with the
maintained saturated water vapor pressure of 0.05 MPa. The heat
treatment was performed under adjusted conditions, for example, by
adjusting the running distance and the running speed of the fiber
bundle, so that the fiber bundle was treated with saturated water
vapor for about 1.0 second.
[Dry Heat Treatment Step]
[0096] A dry heat treatment was performed at a draw ratio of 1.0
(constant length) on a hot plate with a surface temperature of
360.degree. C. The resulting poly m-phenylene isophthalamide fiber
was rolled.
[Physical Properties of Long Fiber]
[0097] The poly m-phenylene isophthalamide drawn fiber was
sufficiently dense with a fineness of 0.8 decitex, a density of
1.33 g/cm.sup.3, a tensile strength of 3.68 cN/dtex, and an
elongation of 42%. The fiber had desirable mechanical
characteristics, and there was no variation in quality. There was
also not observed any abnormal yarn.
[Cutting Step]
[0098] A fiber bundle was produced from the roll of the poly
m-phenylene isophthalamide fiber after the dry heat treatment.
Water was imparted to the fiber bundle to make the moisture content
15%. The fiber bundle was then cut into staple fibers with a fiber
length of 3.0 millimeters, using an Eastman rotary cutter fiber
cutting device with a blade interval of 3.0 millimeters. The fiber
bundle was cut with a draft rate of 1.02 between the rotary cutter
and feed rollers under the pressure of a pressure roller pressing
the fiber bundle against the cutter blade. Table 3 shows the
evaluation results, including the fineness, the moisture content,
the cut-end coefficient, the coefficient of variation relative to
fiber length, and the water dispersibility of the meta-type wholly
aromatic polyamide non-crimped staple fiber.
Example 7
[0099] Four of the fiber bundles produced by imparting water to the
poly m-phenylene isophthalamide fiber rolled after the dry heat
treatment in the manner described in Example 6 were disposed side
by side to produce a fiber bundle. The fiber bundle prepared from
the four parallel fiber bundles was frozen at an atmospheric
temperature of -12.degree. C. for 15 hours while being dipped in a
cylindrical container charged with boiled processing water to
obtain a fiber bundle contained in ice. The fiber bundle in ice was
cut into a fiber length of 1.0 millimeters using a known guillotine
fiber-bundle cutter device (Onouchi Seisakusho, Model: D100) that
had been adjusted to make this fiber length. The meta-type wholly
aromatic polyamide non-crimped staple fiber was evaluated after
being thawed. The results are presented in Table 1.
Example 8
[0100] The same procedures used in Example 7 were performed, except
that the fiber bundle was cut into a staple fiber with a fiber
length of 0.02 millimeters. The meta-type wholly aromatic polyamide
non-crimped staple fiber was evaluated after being thawed. The
results are presented in Table 3.
TABLE-US-00003 TABLE 3 Unit Ex. 6 Ex. 7 Ex. 8 Fiber configuration
-- Single component Single component Single component fiber fiber
fiber Organic resin -- meta-type Wholly meta-type Wholly meta-type
Wholly aromatic polyamide aromatic polyamide aromatic polyamide
Cutting method -- Rotary cutter Ice pillar + Ice pillar +
guillotine guillotine Fineness dtex 0.80 0.80 0.80 Fiber length mm
3.0 1.0 0.02 Moisture content weight % 15 15 15 Cut-end coefficient
-- 1.07 1.25 1.35 coefficient of variation % 3.3 10.0 15.0 relative
to fiber length Water dispersibility -- Good Good Good
Comparative Example 4
[0101] The fiber bundle produced by imparting water to the poly
m-phenylene isophthalamide fiber rolled after the dry heat
treatment in the manner described in Example 6 was cut into a fiber
length of 3.0 millimeters to obtain a non-crimped staple fiber,
using a known guillotine fiber-bundle cutter device (Onouchi
Seisakusho, Model: D100) that had been adjusted to make this fiber
length. The evaluation results for the meta-type wholly aromatic
polyamide non-crimped staple fiber are presented in Table 4.
Comparative Example 5
[0102] The fiber bundle produced by imparting water to the poly
m-phenylene isophthalamide fiber rolled after the dry heat
treatment in the manner described in Example 6 was cut into a fiber
length of 1.0 millimeters to obtain a non-crimped staple fiber,
using a known guillotine fiber-bundle cutter device (Onouchi
Seisakusho, Model: D100) that had been adjusted to make this fiber
length. The evaluation results for the meta-type wholly aromatic
polyamide non-crimped staple fiber are presented in Table 4.
Comparative Example 6
[0103] The same procedures used in Example 6 were performed to
obtain a non-crimped staple fiber, except that the fiber was cut
with a draft rate of 0.98 between the rotary cutter and the feed
rollers. The evaluation results for the meta-type wholly aromatic
polyamide non-crimped staple fiber are presented in Table 4.
TABLE-US-00004 TABLE 4 Unit Com. Ex. 4 Com. Ex. 5 Com. Ex. 6 Fiber
configuration -- Single component Single component Single component
fiber fiber fiber Organic resin -- meta-type Wholly meta-type
Wholly meta-type Wholly aromatic polyamide aromatic polyamide
aromatic polyamide Cutting method -- Guillotine Guillotine Rotary
cutter Fineness dtex 0.80 0.80 0.80 Fiber length mm 3.0 1.0 3.0
Moisture content weight % 15 15 15 Cut-end coefficient -- 1.60 1.80
1.08 coefficient of variation % 33.0 60.0 17.0 relative to fiber
length Water dispersibility -- Poor Poor Acceptable
Example 9
[0104] High-density polyethylene (HDPE) with an MFR of 20 g/10 min
and a melting point Tm of 131.degree. C. was selected as a
low-melting-point thermal binder component, and isotactic
polypropylene (PP) with an MFR of 39 g/10 min and a Tm of
160.degree. C. was selected as a fiber forming component. These
polyolefins were separately melted with different extruders, and
melt ejected through a concentric core-sheath conjugate spinneret
having 1336 round ejection holes. The polymers were ejected as a
conjugate of 245.degree. C. molten polymers with a composition
containing an HDPE sheath component and a PP core component in a
sheath-to-core ratio of 50:50 (weight ratio). Here, the polymers
were melt ejected at a rate of 190 g/min with a spinneret
temperature of 260.degree. C. The ejected polymer was cooled with
27.degree. C. cool air at a position 31 mm below the spinneret, and
a polyether.cndot.polyester copolymer emulsion was imparted to the
yarns with an oiling roller. The fiber was then taken up at 1300
m/min to obtain an undrawn yarn. The undrawn yarn was bundled, and
drawn 4.10 times in 95.degree. C. hot water. After imparting a
polyether.cndot.polyester copolymer as draw oil, the fiber was
dried at 105.degree. C. for 60 min to obtain a
polyethylene/polypropylene conjugate fiber bundle having a single
yarn fineness of 0.32 decitex, and a total fineness of 70000
denier. After imparting water to the conjugate fiber bundle with an
oiling roller to make the moisture content 15%, the fibers were cut
into staple fibers with a fiber length of 3.0 millimeters, using an
Eastman rotary cutter fiber cutting device with a blade interval of
3.0 millimeters. The fiber bundle was cut with a draft rate of 1.02
between the rotary cutter and feed rollers under the pressure of a
pressure roller pressing the fiber bundle against the cutter blade.
Table 3 shows the evaluation results, including the fineness, the
moisture content, the cut-end coefficient, the coefficient of
variation relative to fiber length, and the water dispersibility of
the polyolefin non-crimped conjugate staple fiber.
Example 10
[0105] Isotactic polypropylene (PP) with an MFR of 39 g/10 min and
a melting point Tm of 160.degree. C. was selected as an organic
resin for forming a staple fiber. The isotactic polypropylene was
melted with an extruder, and melt ejected as a 255.degree. C.
molten polymer using a spinneret having 3000 round ejection holes.
Here, the polymer was ejected at a rate of 190 g/min with a
spinneret temperature of 260.degree. C. The ejected polymer was
cooled with 27.degree. C. cool air at a position 25 mm below the
spinneret, and taken up at 1300 m/min to obtain an undrawn yarn.
The undrawn yarn was bundled, and drawn 2.70 times in 95.degree. C.
hot water. After imparting a polyether-polyester copolymer as draw
oil, the drawn yarn was dried at 110.degree. C. for 60 min to
obtain a polypropylene fiber bundle having a single yarn fineness
of 0.30 decitex, and a total fineness of 70000 denier. After
imparting water to the polypropylene fiber bundle with an oiling
roller to make the moisture content 15%, the fibers were cut into
staple fibers with a fiber length of 3.0 millimeters, using an
Eastman rotary cutter fiber cutting device with a blade interval of
3.0 millimeters. The fibers were cut with a draft rate of 1.02
between the rotary cutter and feed rollers under the pressure of a
pressure roller pressing the fiber bundle against the cutter blade.
Table 5 shows the evaluation results for the polypropylene
non-crimped staple fiber.
Example 11
[0106] High-density polyethylene (HDPE) with an MFR of 20 g/10 min
and a melting point Tm of 131.degree. C. was selected as an organic
resin for forming a staple fiber. The high-density polyethylene was
melted with an extruder, and melt ejected as a 210.degree. C.
molten polymer using a spinneret having 144 round ejection holes.
Here, the polymer was ejected at a rate of 15 g/min with a
spinneret temperature of 210.degree. C. The ejected polymer was
cooled with 27.degree. C. cool air at a position 25 mm below the
spinneret, and taken up at 1000 m/min to obtain an undrawn yarn.
The undrawn yarn was bundled, and drawn 3.60 times in 95.degree. C.
hot water. After imparting a polyether-polyester copolymer as draw
oil, the drawn yarn was dried at 105.degree. C. for 60 min to
obtain a polyethylene fiber bundle having a single yarn fineness of
0.32 decitex, and a total fineness of 70000 denier. After imparting
water to the polyethylene fiber bundle with an oiling roller to
make the moisture content 15%, the fibers were cut into staple
fibers with a fiber length of 3.0 millimeters, using an Eastman
rotary cutter fiber cutting device with a blade interval of 3.0
millimeters. The fibers were cut with a draft rate of 1.02 between
the rotary cutter and feed rollers under the pressure of a pressure
roller pressing the fiber bundle against the cutter blade. Table 5
shows the evaluation results for the polyethylene non-crimped
staple fiber.
TABLE-US-00005 TABLE 5 Unit Ex. 9 Ex. 10 Ex. 11 Fiber configuration
-- Sheath-core conjugate Single Single fiber component fiber
component fiber Organic resin -- Core component: PP, PP HDPE Sheath
component: PE Cutting method -- Rotary cutter Rotary cutter Rotary
cutter Fineness dtex 0.32 0.30 0.32 Fiber length mm 3.0 3.0 3.0
Moisture content weight % 15 15 15 Cut-end coefficient -- 1.03 1.03
1.04 coefficient of variation % 3.8 4.5 4.8 relative to fiber
length Water dispersibility -- Good Good Good
Comparative Example 7
[0107] Twenty of the non-crimped polypropylene/polyethylene
sheath-core conjugate fiber bundles obtained after imparting water
in the manner described in Example 9 were bundled to obtain a fiber
bundle of 1400000 decitex. The fiber bundle was then wrapped in
paper. The wrapped sheath-core conjugate fiber bundle was cut into
a fiber length of 3.0 millimeters to obtain a non-crimped staple
fiber, using a known guillotine fiber-bundle cutter device (Onouchi
Seisakusho, Model: D100) that had been adjusted to make this fiber
length. The evaluation results for the polypropylene/polyethylene
sheath-core conjugate staple fiber are presented in Table 6.
Comparative Example 8
[0108] Twenty of the polypropylene fiber bundles obtained after
imparting water in the manner described in Example 10 were bundled
to obtain a fiber bundle of 1400000 decitex. The fiber bundle was
then wrapped in paper. The wrapped polypropylene fiber bundle was
cut into a fiber length of 3.0 millimeters to obtain a non-crimped
staple fiber, using a known guillotine fiber-bundle cutter device
(Onouchi Seisakusho, Model: D100) that had been adjusted to make
this fiber length. The evaluation results for the polypropylene
non-crimped staple fiber are presented in Table 6.
Comparative Example 9
[0109] Twenty of the polyethylene fiber bundles obtained after
imparting water in the manner described in Example 11 were bundled
to obtain a fiber bundle of 1400000 decitex. The fiber bundle was
then wrapped in paper. The wrapped polyethylene fiber bundle was
cut into a fiber length of 3.0 millimeters to obtain a non-crimped
staple fiber, using a known guillotine fiber-bundle cutter device
(Onouchi Seisakusho, Model: D100) that had been adjusted to make
this fiber length. The evaluation results for the polyethylene
non-crimped staple fiber are presented in Table 6.
TABLE-US-00006 TABLE 6 Unit Com. Ex. 7 Com. Ex. 8 Com. Ex. 9 Fiber
configuration -- Sheath-core conjugate Single Single fiber
component fiber component fiber Organic resin -- Core component:
PP, PP HDPE Sheath component: PE Cutting method -- Guillotine
Guillotine Guillotine Fineness dtex 0.32 0.30 0.32 Fiber length mm
3.0 3.0 3.0 Moisture content weight % 15 15 15 Cut-end coefficient
-- 1.50 1.60 1.60 coefficient of variation % 50.0 70.0 75.0
relative to fiber length Water dispersibility -- Poor Poor Poor
Comparative Example 10
[0110] The same procedures used in Example 9 were performed to
obtain a non-crimped staple fiber, except that the fibers were cut
at a draft rate of 0.98 between the rotary cutter and the feed
rollers. The evaluation results for the polyethylene/polypropylene
sheath-core conjugate non-crimped staple fiber are presented in
Table 7.
Comparative Example 11
[0111] The same procedures used in Example 10 were performed to
obtain a non-crimped staple fiber, except that the fibers were cut
at a draft rate of 0.98 between the rotary cutter and the feed
rollers. The evaluation results for the polypropylene non-crimped
staple fiber are presented in Table 7.
Comparative Example 12
[0112] The same procedures used in Example 1 were performed to
obtain a non-crimped staple fiber, except that water was sprayed to
make the moisture content 1.0% before being supplied to the rotary
cutter to be cut. The evaluation results for the polyester
non-crimped staple fiber are presented in Table 7.
TABLE-US-00007 TABLE 7 Unit Com. Ex. 10 Com. Ex. 11 Com. Ex. 12
Fiber configuration -- Sheath-core conjugate Single Single fiber
component fiber component fiber Organic resin -- Core component:
PP, PP PET Sheath component: PE Cutting method -- Rotary cutter
Rotary cutter Rotary cutter Fineness dtex 0.32 0.30 0.51 Fiber
length mm 3.0 3.0 3.0 Moisture content weight % 15 15 1.0 Cut-end
coefficient -- 1.04 1.05 1.15 coefficient of variation % 25.0 32.0
25.0 relative to fiber length Water dispersibility -- Poor Poor
Poor
* * * * *