Note: Descriptions are shown in the official language in which they were submitted.
CA 02336245 2000-12-20
POLYPARAPHENYLENE TEREPHTHALAMIDE FIBER AND
METHOD FOR PRODUCING THE SAME
Technical Field of the Invention
The present invention relates to para system aramide fiber
and method for producing the same.
Background Art of the Invention
Polyparaphenylene terephthalamide fiber (hereinaf,ter,
referred to as para system aramide fiber) is a synthetic fiber
having high functions such as of high strength, high modulus
elasticity, high thermal resistance, non-electro-conductivity,
and no rust occurrence, as well as having flexibility and
lightweight property, which are characteristics of organic
fibers. From these properties, it is used as a reinforcement
material for a tire for a motorcar, a motorcycle and a bicycle,
a timing belt for a motorcar, a conveyer and the like. Further,
it is also used for reinforcing an optical fiber cable, and as a
rope. Furthermore, it is also applied to a bulletproof jacket,
protection clothes which are formed as working gloves and
working clothes by utilizing the feature being hard to be cut
against an edged tool, and clothes for fire fighting formed by
utilizing the feature being hard to burn.
In these applications, nevertheless a dyeable property is
required in addition to the above-described properties, it has
been difficult to dye aramide fiber, because of its high
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crystallinity, and its minute structure due to high
intermolecular force.
The following methods have been proposed so far, as methods
for dyeing aramide fibers.
JP-A-SHO 50-12322 proposes a method for diffusing additives
such as dye, antioxidant, ultraviolet insulation agent, and
fireproofing agent in a fiber expanded by water. However, JP-A-
SHO 50-12322 does not describe with respect to diffusion of all
kinds of dyes into fibers, and also does not specify the
conditions. Especially, it does not describe dyeing under a
condition of a water content of 500 or less.
JP-A-SHO 54-59476 discloses a method for dyeing from
buckling portions of a fiber after providing crimps to the fiber
at 10 crimps/inch or more. Further, JP-A-HEI 2-41414 discloses
a method for adding an organic pigment to a dope for spinning.
JP-A-SHO 63-145412 proposes a method for introducing para
oriented aramide into a process, in which the tension is
relaxed, at a coagulation step immediately after spinning,
thereby bringing it into contact with a dyeing solution.
Further, JP-A-HEI 7-258980 proposes a method for bringing para
system aromatic polyamide, whose inherent viscosity is 2.5 dl/g
or less and which is expanded by water, into contact with a
dyeing solution. JP-A-HEI 8-260362 discloses a method for
dyeing by a cation system dye at a temperature of 130 C or
higher, while using a fiber expansion agent. JP-A-HEI 5-209372
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discloses a method for dyeing a copolymerized para system
aramide fiber at a temperature of 160 C; or higher by using a
dispersed dye having a molecular weight of 400 or less.
Furthermore, JP-A-HEI 9-87978 and JP-A-HEI 9-87979 propose a
method for dyeing a para system aramide fiber under a condition
of a high pressure and a temperature of 200 C after treating it
with a polar solvent such as dimethylsulfoxide.
In the method of the above-described JP-A-SHO 54-59476,
however, for a high-strength and rigid para system aramide
fiber, it is difficult to provide crimps at 10 crimps/inch or
more, and this method is restricted for a formation of a staple.
The method disclosed in JP-A-HEI 2-41414 is a proposal for a so-
called originally colored spinning, and the method described in
JP-A-SHO 63-145412 is a method for bringing a fiber into contact
with a dye solution at a tension-free condition without winding
it after spinning. In any method, a fairly large volume of
production per one color is required, and the color employed is
limited. In the method disclosed in JP-A-HEI 7-258980, the
strength of a fiber is extremely low because of a low viscosity
of the polymer, and therefore, the method cannot satisfy the
feature of high strength which aramide fiber essentially has.
The method disclosed in JP-A-HEI 8-260362 is a proposal for a
spun yarn, which is inferior to a filamentary yarn in tensile
strength and tensile elastic modulus, and therefore, it is not
satisfied as a method for dyeing a filament capable of utilizing
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the function of a high strength and a high elastic modulus of
original aramide fiber. The methods disclosed in JP-A-HEI 5-
209372, JP-A-HEI 9-87978 and JP-A-HEI 9-87979 are not common,
because they require special equipment such as one for recovery
of a polar solvent or for high-temperature dyeing.
So far, a method for post-dyeing capable of applying various
colors at a form of a filament which cari maintain the features
of high-strength and high-elastic modulus of aramide fiber,
namely, a method for dyeing various colors in a dyeing process,
capable of dyeing at respective colors individually from each
other, separatedly and after a process in which a spun filament
is once wound onto a tube-like material, has not yet been
realized.
A yarn forming process for forming a filamentary yarn and a
dyeing process for dyeing the yarn generally are separated from
each other, and the respective processes are performed by
respective technical experts using respective exclusive
equipment. To satisfy severe requirements of customers as to
colors of dyed textile products, it is important to break off
the process once after producing fibers, and to transport the
fibers to a plant for dyeing and dye the fibers in respective
colors, that customers require, by technical experts for dyeing.
Disclosure of the Invention
Accordingly, it is an object of the present invention to
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provide a para system aramide fiber which can be dyed while its
properties of high strength and high modulus elasticity can be
maintained, and a para system aramide fiber dyed in various
colors.
To accomplish this object, the present invention takes the
following ways.
(1) A dyeable polyparaphenylene terephthalamide fiber which has
been wound once after spinnig and has not been dyed yet,
characterized in that the fiber has a tensile strength of 15
g/denier or more and a crystal size (110 direction) of 30 to 55
angstroms and has no history of a treatment drying to have a
water content of 8% or less.
(2) The dyeable polyparaphenylene terephthalamide fiber
according to the above-described (1), wherein the fiber has no
history of a treatment drying to have a water content of 15% or
less.
(3) A staple type of dyeable polyparaphenylene terephthalamide
fiber, wherein the fiber according to the above-described (1) or
(2) is treated to be provided with 4 to 9 crimps/25mm, and cut
at a fiber length of 20 to 150 mm.
(4) A flock type of dyeable polyparaphenylene terephthalamide
fiber, wherein the fiber according to the above-described (1) or
(2) is cut at a length of 0.1 to 3 mm.
(5) A dyed polyparaphenylene terephthalamide fiber, wherein the
fiber according to the above-described (1) or (2) is dyed.
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(6) The dyed polyparaphenylene terephthalamide fiber according
to the above-described (5), wherein the fiber is dyed by a
cation dye.
(7) A staple type of dyed polyparaphenylene terephthalamide
fiber, wherein the staple type of polyparaphenylene
terephthalamide fiber according to the above-described (3) is
dyed.
(8) The staple type of dyed polyparaphenylene terephthalamide
fiber according to the above-described (7), wherein the fiber is
dyed by a cation dye.
(9) A flock type of dyed polyparaphenylene terephthalamide
fiber, wherein the flock type of polyparaphenylene
terephthalamide fiber according to the above-described (4) is
dyed.
(10) The flock type of dyed polyparaphenylene terephthalamide
fiber according to the above-described (9), wherein the fiber is
dyed by a cation dye.
(11) A method for producing a dyeable polyparaphenylene
terephthalamide fiber by a filament forming step and a filament
dyeing step, performed separatedly from each other, the filament
forming step being performed by preparing a dope for spinning
from polyparaphenylene terephthalamide having an inherent
viscosity (r7 inh) of 5 or more and a concentrated sulphuric acid,
once spinning the dope in air through fine holes of a spinning
die, and immediately thereafter, introducing the spun dope into
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water to coagulate it to form a high-strength and high-modulus
elasticity filament, characterized in that the fiber has a
tensile strength of 15 g/denier or more and a crystal size (110
direction) of 30 to 55 angstroms, and a water content of the
fiber is always maintained at 8 or more.
(12) A method for cheese-dyeing the dyeable polyparaphenylene
terephthalamide fiber produced by the method according to the
above-described (11) by using a cation dye at a condition of a
number of twist defined by a coefficient of twist of 0.2 or less
represented by the following equation.
K=(T f D)/2870
K: coefficient of twist
T: number of twist (number/m)
D: fiber size in absolute dry condition (denier)
The Best mode for carrying out the Invention
A polyparaphenylene terephthalamide (hereinafter, also
referred to as "PPTA") according to the present invention is a
polymer obtained by polycondensation of terephthalic acid and
paraphenylenediamine, and a small amount of dicarboxylic acid
and diamine may be copolymerized. Polyparaphenylene
terephthalamide fiber (hereinafter, referred to as "para system
aramide fiber") according to the present invention is produced
by making an optically anisotropic dope from PPTA having an
inherent viscosity inh) of 5 or more and a concentrated
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sulphuric acid, once spinning the dope in air through fine holes
of a spinning die, immediately thereafter, introducing the spun
dope into water to coagulate it, introducing it into a Nelson
roller and neutralizing it in a sodium hydroxide solution,
slightly drying it by a hot roller after a water washing
process, and passing it through a process for continuously
winding it on a tube as a filament. Para system aramide fiber
wound is wrapped by a wrapping material such as a polyethylene
film so as to prevent it from being dried before being sent to a
drying process. The crystallinity of the para system aramide
fiber in this step is 50% or less. Although the tensile modulus
elasticity of the fiber is over 400 g/denier and it has a
feature as a high-modulus elasticity fiber, in order to further
increase the modulus elasticity, the fiber is heat treated at a
temperature of 350 to 400 C for 5 to 10 seconds after drying, and
by this treatment, the crystallinity is generally increased up
to a degree over 50%.
The inherent viscosity ( r1inh) of PPTA used in the present
invention is preferably 5 or more. If the inherent viscosity (
77inh) is less than 5, it is hard to obtain the fiber properties
of high strength and high modulus elasticity.
In the para system aramide fiber according to the present
invention, it is necessary that the crystal size (110 direction)
is in a range of 30 to 55 angstroms and the water content is
always more than 80. If the crystal size is less than 30
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angstroms, it is difficult to sufficiently densify the fiber and
to achieve the fiber properties of high strength and high
modulus elasticity, and if the crystal size is more than 50
angstroms, it is difficult to dye.
Where, "the water content is always more than 8%" means that
it has no history of a treatment that has dried it at a water
content of 8% or less. If the fiber is dried at a water content
of 8a or less, the structure is too densified and it becomes
hard to dye it. In such a condition, even if water is provided
again, the dyeability cannot be recovered. Preferably, the
water content of para system aramide fiber is in a range of 15
to 49%. If the water content is 50% or more, it is difficult to
wind the fiber because the frictional resistance between the
fiber and guide rolls and the like becomes great. To control
such a preferable water content, it is desired to dry the spun
para system aramide fiber at a hot roller temperature of 100 to
150 C for 5 to 20 seconds. If drying temperature is lower than
100 C, it is difficult to remove water, and occurs a problem in
handling after winding the fiber onto a tube. If higher than 150
C , it is difficult to dye because the crystallinity is too
accelerated.
In the present invention, para system aramide fiber having
such properties is served to a dyeing treatment. For the method
for dyeing, a particular apparatus and a particular method are
not required, and an existing apparatus for dyeing synthetic
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fibers can be used. The dyeing is achieved by controlling pH by
adding an assistant and an acid to a proper amount of dye,
starting to dye at, for example, 60 C, elevating the temperature
to 130 C for 60 minutes, and dyeing for 30 minutes. As the dye
to be used in a condition of a water content less than 50%, a
cation dye, which easily permeates even into a dense structure
of fiber, is most desirable.
Para system aramide fiber according to the present invention
is useful to various applications. Dyed para system aramide
fiber filament can be used as machine cottons, cords, ropes and
woven fabrics with various colors. Para system aramide fiber
fabrics with various colors obtained by the present invention
can be used for clothing for sports, bag texture, working
clothes, clothes for fire fighting, and various kinds of
protection clothes, tents clothes and other applications. In a
texture for bulletproof jacket dyed in an inconspicuous color,
even if the outer skin is broken by shot and the para system
aramide fiber used as a bulletproof texture is exposed, it is
not conspicuous.
Further, as products applied with dyed para system aramide
fiber according to the present invention, seat belts for
motorcars, protection clothes for speedboat race players,
bowstrings, tennis guts, fishing lines and the like can be
raised. In a case where dyed para system aramide fiber
according to the present invention is used as a reinforcing
CA 02336245 2000-12-20
material of a transparent or semi-transparent resin, it may be
produced as a colorful resin product because the colored
reinforcing material can be seen through the transparent or
semi-transparent resin. For example, such a structure can be
employed for a glass frame made from resin, a frame of tennis
racket, a hockey stick, a fishing rod, a golf shaft and the
like. In a case where the resin is an elastomer, it is useful
for a force transmitting resin belt, a resin hose, a bicycle
tire and the like. Para system aramide fiber according to the
present invention can be applied to ropes or electric wires
whose production year is indicated by colors. In a bundle of
electric wires, reinforcement of each electric wire and
discrimination of a terminal of each electric wire can be both
achieved by using reinforcing materials having the respective
colors different from each other. It can also be used for a so-
called lip cord, in which the fiber is provided under the
covering material of the electric wire and the covering material
can be cut by using the fiber to expose the wire terminal.
A colored para system aramide fiber staple can be obtained
by passing a dyed para system aramide fiber filament through a
crimper to provide 4 to 9 crimps/25mm (for example, 6
crimps/inch) similarly to that in commercial para system aramide
fibers, and cutting the crimped fiber at a length suitable for
spinning, namely, at a length of 20 to 150 mm. The dyed para
system aramide fiber can be made as flocks for electrical
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.74023-32
flocking by cutting it at a length of a 1 to 3 mm without crimping.
In the present invention, it may be performed that para system
aramide fiber before dyeing is crimped and cut, and after making
a staple, it is dyed. Similarly, it may be performed that the
fiber is dyed after being cut to make flocks for electrical
flocking.
Examples
The present invention will be hereunder explained based on
Examples. The following methods for estimating properties in
the were employed.
(1) Crystal size
It is determined by wide angle X-ray diffraction method.
= X-ray analysis apparatus: Type 4036A2 produced by Rigaku Denki
corporation
X-ray source . CuKa ray
curved'crystal monochorometer
(used with graphite)
(2) Inherent viscosity
Inherent viscosity ( 77 inh) is determined by a regular
method, using a solution in which a polymer is dissolved in a
concentrated sulphuric acid with a concentration of 98.5 wt% at
a polymer concentration (C) of 0.5 g/dl and at a temperature of
30 C.
n inh = ( ln = 77 rel ) /C
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(3) Tensile strength and Elongation properties of fiber
Tensile strength and tensile modulus elasticity (initial
tensile resistance) of fiber are determined according to JIS-L-
1013.
(4) Water content
Water content is determined according to JIS-L-1013.
Water content (w-W') X100/W'
Where,
W: mass of a sample at the time when the sample is taken
W': mass of the sample in absolute dry condition
(5) L value
L value is determined according to JIS-Z-8729. As the
nieasurement apparatus, Macbeth Color Eyes 3000 produced by
Sumika Bunseki Center Corporation is used.
Example 1, Comparative Example 1:
Para system aramide fiber A (filamentary yarn), which had a
filament number of 1,000 and a total size of 1,500 deniers
(converted into absolute dry condition) was produced by
dissolving PPTA prepared by a usual method (71 inh = 6.5) in
concentrated sulphuric acid with a concentration of 99.9 % to
prepare a dope for spinning having a polymer concentration of
19.0 % at a temperature of 80 C, after spinning the dope in air
through_1,000 fine holes each having a diameter of 0.06 mm of a
die for a moment, introducing the spun dope into water of 40 C to
*Trade-mark
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=74023-32
coagulate it, introducing it into Nelson roller, neutralizing it
by 8% sodium hydroxide solution, after washing, drying it by a
hot roller for 15 seconds and winding it continuously onto a
plastic tube.
Further, dried para system aramide fiber B (filamentary
yarn) was produced by introducing the para system aramide fiber
A, without winding, into a following hot roller to further heat
treat it at a temperature of 350 C for 10 seconds, and
thereafter, winding it.
The properties of these para system aramide fibers are shown
in Table 1.
Table 1
Kind of fiber A B
Crystal size (A)110 direction 42 65
Tensile strength (g/denier) 23.0 22.2
Tensile modulus elasticity(g/denier) 565 850
Water .content (%) 48 2.2
These para system aramide fiber filamentary yarns were dyed
in a dark blue at the following conditions. The "owf" indicates
wt% of a.dye relative to fiber weight of a dried fiber. "g/1"
indicates weight ratio of an assistant relative to 1 liter of a
dyeing bath prepared.
Dyes (cation dyes):
"ASTRAZON GOLDEN YELLOW GL"
(Cl YELLOW 28, produced by DYSTER Corporation) : 0.1 %owf
"I'.AYACRYL* RED GL"
*Trade-mark
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.74023-32
(Cl RED 29, produced by Nippon Kayaku Corporation) : 2.0 %owf
"AIZEN*CATHILON BLUE TBLH"
(produced by Hodogaya Kagaku Corporation) : 8.0 '-6owf
Assistant:
"Neodespori AC" (produced by Mohrin Corporation) : 2 g/l
Acetic acid : 1 g/l
Nitric acid sodium : 20 g/l
"Terealcarrier Al11" (produced by Meisei Kagaku Corporation)
20 g/l
A sample of the para system aramide fiber was taken by a
weight of 10 g as a weight converted into absolute dried
condition, it was started to be dyed at a condition of a bath
ratio of 1:15 and a temperature of 60 C, the temperature was
elevated up to 130 C for 60 minutes, and it was dyed for 30
minutes. After dyeing, it was served to reduction cleaning in a
bath of an anti-ion active agent and a reductant at 80 C for 20
minutes, and after dehydrated and dried, L value was determined.
The smaller the L value is, the smaller the reflection of a
light is and the darker the color tone is. In a case of an
identical color, the smaller the L value is, the better it is
dyed. In the dyeing method using the dyeing bath prepared in the
above-described manner, a grade of 50 or less in L value was
determined to be well-dyed.
Para system aramide fiber A adsorbed the dye well, but para
system aramide fiber B almost was not dyed.
* Trade-mark
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Examples 2 to 4, Comparative Example 2:
Para system aramide fiber A was left at a room temperature
to release water, the water content before dyeing was varied,
and then it was dyed at the same condition as that of the above-
described Example. The fibers were well dyed except in
Comparative Example 2 of a water content of 5 s.
Comparative Example 3:
Para system aramide fiber A was dyed under the
aforementioned condition after the water content before dyeing
had been controlled at 0 % by drying the fiber at 100C for 60
minutes using a circulation type hot-air dryer. However, it
almost was not dyed.
The results of these Examples and Comparative Examples are
shown in Table 2.
Table 2
Kind Water L value Tensile Tensile
of content strength modulus
fiber elasticity
(o) (g/denier) (g/denier)
Comparative B 2.2 65.6 22.2 830
Example 1
Example 1 A 48 45.4 23.0 565
Example 2 A 45 45.5 23.0 565
Example 3 A 28 45.4 23.0 565
Example 4 A 12 46.0 23.0 565
Comparative A 5 50.2 23.0 565
Example2
Comparative A 0 65.2 23.0 565
Example 3
Example 5:
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The yarn of para system aramide fiber A was wound, without
adding a twist to the yarn, onto a plastic tube at a tension of
0.04 g/denier, which tube has an inner diameter of 51 mm, an
outer diameter of 57 mm and a length of 250 mm length and has
many holes each having a diameter of 8 mm on the portion that
the yarn is to be wound. The amount of winding was set at 1 kg
as a weight in absolute dried condition. It was dyed under the
aforementioned condition, using a cheese-dyeing apparatus, in
which a dyeing solution was circulated from the holes defined on
the plastic tube to the outside of the cheese through the yarn.
The water content of the para system aramide fiber before dyeing
determined was 48 %. Because the para system aramide fiber A
slightly released water and its volume decreased accompanying
with the elevating temperature during dyeing, gaps were formed
between fibers and the dyeing solution was well circulated. L
value of the para system aramide fiber A after dyeing was 45.5,
and it was well dyed. Tensile strength of the dyed para system
aramide fiber was 23.0 g/denier, tensile modulus elasticity was
565 g/denier, and they were satisfactory as properties of a
high-strength and high-modulus elasticit.y para system aramide
fiber.
Comparative Example 4:
Twists were added to the yarn of para system aramide fiber A
by a ring twister at a number of twist of 74/m corresponding to a
coefficient of twist = 1 defined by the below equation. This
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twisted yarn was cheese-dyed in the same manner as that of
Example 5. Because the filamentary yarn had a circular section
by the twisting and a space was formed between yarns at a state
wound on a plastic tube, the circulation of the dyeing solution
during dyeing was better than that in Example 5. However,
partially there occurred an insufficient dyeing portion having a
low concentration.
Water in the filament was released by ballooning at the
twisting and a centrifugal force exerted on a rotating bobbin,
and it was observed that water drops were splashed around the
twister. As a result, low-water content portions were formed
partially on the para system aramide fiber in its longitudinal
direction, and on those portions the dyeing was insufficient.
K=(T~_D)/2870
K: coefficient of twist
T: number of twist (number/m)
D: fiber size in absolute dry condition (denier)
Thus, according to the present invention, a
polyparaphenylene terephthalamide fiber, which can be dyed while
its properties of high strength and high modulus elasticity are
maintained, and a polyparaphenylene terephthalamide fiber dyed
in a variety of colors, can be provided.
Industrial Applications of the Invention
In the present invention, a polyparaphenylene
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terephthalamide fiber, which can be dyed while its properties of
high strength and high modulus elasticity are maintained, and a
polyparaphenylene terephthalamide fiber dyed in a variety of
colors, can be provided. The para system aramide fiber
according to the present invention is suitable for various
applications, especially the dyed para system aramide fiber
filament can be used as machine cottons, cords, ropes and
textiles with various colors. Para system aramide fiber textile
with various colors according to the present invention can be
used as clothing for sports, bag texture, working clothes,
clothes for fire fighting, and various kinds of protection
clothes, tents clothes and other applications.
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