JPH09157948A - Production of polybenzazole fiber and production device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently reduce a basic unit and to obtain a polybenzazole fiber excellent in productivity by using a polybenzazole prepared by solution polymerization in an acid solvent, extruding a dope filament from a spinneret and continuously supplying the dope filament to a spinning process for staple when an end breakage occurs. SOLUTION: A polybenzazole polymer is obtained by solution polymerization in an acid solvent, a polymerization solution is directly extruded as spinning dope from a spinneret 1. A spinning position having caused an end breakage is continuously supplied to a spinning process for staple. A prepared dope filament is coagulated/washed/dried to give a polybenzazole fiber. The fiber is obtained by using a production apparatus equipped with a conveyor 5 transporting a fiber having passed a coagulating bath 2 to a staple can 6, below take-off rollers 3 arranged at an outlet of the coagulating bath 2 of each spinning position. A suction device 4 for fiber is preferably installed between the take-off rolls 3 and the conveyor 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing fibers of high-strength, high-modulus polybenzoxazole. More specifically, the present invention relates to a method and an apparatus for producing fibers of high-strength and high-modulus polybenzoxazole with a low basic unit.

[0002]

2. Description of the Related Art Polybenzazole fiber has a strength and elastic modulus more than twice that of polyparaphenylene terephthalamide fiber, which is a typical super fiber currently on the market. Therefore, it is expected as a next-generation super fiber. It is known to make fibers from polyphosphoric acid solutions of polybenzazole polymers. For example, U.S. Pat. No. 5,296,185 and U.S. Pat. No. 5,294,390 have been proposed for the spinning method, JP-A-7-197307 has been proposed for the drying method, and US Pat. No. 5,288,445 has been proposed for the heat treatment method. US Patent Application 008/425493 has also been proposed for a method of producing staples. Basically, polybenzazole fiber can be produced by these production techniques, but when operating a production line that actually has many weights, it is necessary to solve the problem of reducing the basic unit due to lack of weight due to yarn breakage. is there.

[0003]

When a spinning dope composed of polybenzazole and polyphosphoric acid is produced by a so-called polymerization direct spinning method using a large number of spinning spindles, it is possible to prevent the occurrence of yarn breakage as in conventional wet spinning. It is extremely difficult to stop the polymer supply of the generated weight or store it separately as a dope for spinning. Because, if the polymer supply to the weight is stopped, fluctuation of the polymer quality in the polymerization process is caused, and if the polymer for the weight is stockpiled in order to avoid this, the spinning dope composed of polybenzazole and polyphosphoric acid is used for normal wet spinning. This is because, unlike the dope used in the present invention, the viscosity is extremely high and the spinning temperature easily exceeds 100,000 poise. Therefore, it is difficult to use a separately stocked spinning dope on an industrial scale. The present invention provides a high-speed spinning technology and equipment for overcoming such technical difficulties and minimizing the decrease in the unit consumption of polybenzazole fiber due to the thread breakage weight.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have conducted intensive studies and found a solution to the problem of producing polybenzazole fiber at high speed and at low cost. That is,
A method for producing a polybenzazole filament by subjecting a polybenzazole polymer to solution polymerization in an acid solvent, directly extruding the polymerization solution as a spinning dope from a spinneret, and coagulating / washing / drying the obtained dope filament. A method for producing a polybenzazole fiber, which comprises continuously providing a dope filament to a staple production process without stopping the supply of a spinning dope when a break occurs. In a polybenzazole filament manufacturing apparatus composed of a plurality of spinning spindles, a conveyor for transporting the yarns passing through the coagulation bath to the staple cans at the bottom of the trading roll arranged at the outlet of the coagulation bath of each spindle. An apparatus for producing a polybenzazole fiber, which is provided.

Hereinafter, the present invention will be described in detail. The polybenzazole fiber in the present invention refers to a fiber made of a polybenzazole polymer, and is a polybenzazole (PBZ)
"Polybenzoxazole (PBO) homopolymer, polybenzothiazole (PBT) homopolymer, and random, sequential or block copolymers of PBO and PBT. Here, polybenzoxazole, polybenzothiazole and their random, sequential or block copolymers are described in, for example, "Liquid Crystalline Polymer C" by Wolfe et al.
ompositions, Process and Products, U.S. Patent No. 47
03103 (October 27, 1987), "Liquid C
rystall-ine Polymer Compositions, Process and Pro
ducts "US Patent No. 4,533,692 (August 6, 1985)
Sun), "Liquid Crystalline Poly (2,6-Benzothiazole)
Composition, Process and Products, U.S. Patent No. 45
33724 (August 6, 1985), "Liquid Crys
talline Polymer Compositions, Process and Product
s "U.S. Pat. No. 4,533,693 (August 6, 1985)
Sun), Evers "Thermooxidative-ly Stable Articula
ted p-Benzobisoxazole and p-Benzobisthiazole Polym
res "U.S. Pat. No. 4,539,567 (November 16, 1982); Tasi et al.," Method for making Heterocyclic ".
Block Copolymer "US Pat. No. 4,578,432 (19
March 25, 1986). The structural unit contained in the PBZ polymer is preferably selected from a lyotropic liquid crystal polymer. The monomer units consist of the monomer units described in structural formulas (a) to (h), and more preferably essentially consist of structural formulas (a) to (h).
It consists of monomer units selected from (c).

[0006]

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[0007]

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Suitable solvents for forming the dope of PBZ polymer include cresol and non-oxidizing acids capable of dissolving the polymer. Examples of suitable acid solvents include polyphosphoric acid, methanesulfonic acid and concentrated sulfuric acid or mixtures thereof. Further suitable solvents are polyphosphoric acid and methanesulfonic acid. The most suitable solvent is polyphosphoric acid.

[0009] The polymer concentration in the solvent is preferably at least about 7% by weight, more preferably at least 1% by weight.
0% by weight, most preferably at least 14% by weight. The maximum concentration is limited by practical handling properties such as, for example, polymer solubility and dope viscosity. Due to their limiting factors, the polymer concentration is usually 20% by weight
Never exceed.

[0010] Suitable polymers, copolymers or dopes are synthesized by known techniques. See, eg, Wolfe et al., US Pat. No. 4,533,693 (August 6, 1985), Sy.
U.S. Pat. No. 4,772,678 to Bert et al. (September 2, 1988)
0) Harris U.S. Pat. No. 4,847,350 (198).
(July 11, 2009). PB
Z polymers are disclosed in US Pat. No. 5,089,959 to Gregory et al.
No. (February 18, 1992), it is possible to increase the molecular weight at a high reaction rate under a relatively high temperature and high shear condition in a dehydrating acid solvent.

The dope polymerized in this way is supplied to the spinning section and discharged from the spinneret at a temperature of usually 100 ° C. or higher. The arrangement of the base pores is usually plural in a circumferential or lattice shape, but other arrangements are also possible. The number of pores in the spinneret is not particularly limited, but the arrangement of the spinning pores on the spinneret surface needs to maintain a pore density such that fusion between the discharge yarns does not occur.

The filamentous dope discharged from the spinneret into a non-solidified gas (so-called air gap) is given a draft in the air gap. Providing a so-called quench chamber for cooling the yarn using cooling air in the air gap in order to increase the cooling efficiency of the yarn is particularly effective for obtaining a high spinning speed.

Then, the yarn is introduced into a coagulating liquid and coagulated and / or extracted and washed. The coagulation liquid is preferably a phosphoric acid aqueous solution, and the phosphoric acid aqueous solution has a phosphoric acid concentration of 10% or more and 50% or more and a temperature of 30 ° C. or more and 80 ° C. or less.

The residual phosphorus concentration of the yarn after coagulation and washing is 100
00 ppm or less, preferably 5000 ppm or less. The washing step includes a neutralization step, an alkali metal base is used as a neutralizing agent, and the atomic ratio of the alkali metal to phosphorus remaining in the fiber is 0.5 or more and 1.5 or less. It is particularly preferable because it retains physical properties during post-processing, but is not essential.

The yarn that has undergone the coagulation / washing process is dried in a dryer. The spun yarn spun, coagulated, and washed under the above-mentioned preferable conditions can be dried at a high temperature of 200 ° C. or higher without generating voids that cause deterioration of the physical properties of the fiber. Of course, it is also possible to raise the temperature stepwise and dry. As the dryer, a heat roll, an oven or other dryer can be used.

When this method for producing a polybenzazole filament is used for production on an industrial scale, it is produced using a large number of spinnerets as shown in FIG. As described above, since many yarns are hooked on the same production line at the same time, generally, when a yarn breakage occurs, the basic unit is not reduced and the spinning pump or the like is deficient in weight. For the spinning of polybenzazole, it is desirable to employ a polymerization direct spinning method with high viscosity. In this case, it is not preferable in terms of stability of the polymer to change the amount of polymerization supplied in accordance with the decrease in the required amount of spinning dope required for spinning. Also, as a method of solving the problem, leaving the yarn breakage weight discharged causes waste of the raw material and increases the basic unit.

In the present invention, in order to achieve both stable supply of polymer and productivity, a conveyor (5) is installed below the take-up roll (3) provided at the outlet of the coagulation bath (2) to produce a polybenzazole filament. The yarns of the weight, at which the yarn breakage sometimes occurs, are continuously shaken off onto the conveyor by the suction device (4) above the conveyor. The conveyor is preferably a net conveyor for separating the coagulation bath and the yarn. A staple can (6) is provided at the exit of the conveyor, and the yarn of the yarn breakage weight is taken up by the can. Of course, the number of yarn breaks leading to the yarn hooking of all the yarns in the production line is determined in consideration of productivity, and when the number of yarn breaks reaches the set value, the yarn re-threading of all the yarns in the line is performed.

In this way, the yarns of the yarn breakage weight which have been taken up by the staple cans for a certain period of time are collected and collected as a plurality of yarns by a separate off-line processing device in the same manner as the above-mentioned production of the filaments, and dried. . Preferably, the off-line processor is a staple manufacturing apparatus, and after drying, crimps the yarn and cuts it with a rotary cutter to produce staples. Of course, the processing order may be changed, and it is also possible to perform processing such as washing and drying on the conveyor without using staple cans. The essential technique of the present invention is to install a treatment step different from the filament production line to reduce the polymer basic unit.

EXAMPLES Examples are shown below, but the present invention is not limited to these examples. <Example> Polybenzazole 14.0 having an intrinsic viscosity of 24.4 dL / g measured with a methanesulfonic acid solution at 30 ° C., obtained by the method described in US Pat. No. 4,533,693.
A spinning dope composed of polyphosphoric acid having a (wt)% and a phosphorus pentoxide content of 83.17% was used for spinning. The dope was passed through a metal mesh filter material, and then kneaded and defoamed with a biaxial kneading device, and then the pressure was raised to a polymer solution temperature of 17
17 from 4 spinnerets with 0 holes and 334 holes
The yarn was spun out at 0 ° C., the discharged yarn was cooled with cooling air at a temperature of 60 ° C., and then introduced into a coagulation bath. Spinning speed is 600m
/ Min at 50 ° C. at 20 ° C. with a 20% phosphoric acid aqueous solution, the spinning speed is given by a take-up roll, the yarn is washed in the second and third extraction baths, and then 0.1N hydroxylation is performed. It was immersed in a sodium solution and neutralized. After further washing with a washing bath, it was immediately dried using a dryer. The drying conditions and the physical properties of the obtained fiber are also shown in Table 1. One of the four yarn threads was artificially cut, and then it was shaken off using a suction machine on a net conveyor provided at the lower part of the roll.
The yarn dropped on the can from the end of the net conveyor was separately washed with water and dried. As shown in Table 1, the physical properties of the fiber were not inferior to those of the filament.

Separately collected fibers were washed with water, crimped with a crimper, cut into 44 mm, and dried to form staples. When the staple was formed into a spun yarn through a spinning process, it could be processed without any problems in the manufacturing process, and the spun yarn obtained had excellent yarn physical properties as shown in Table 1, and was obtained by the method of the present invention. It can be seen that the spun yarn obtained is as good as a product at all and is a sufficient production method. Therefore, according to the method of the present invention, the polybenzazole fiber can be inexpensively produced at a value close to the theoretical unit even in a mass production facility where a large number of weights are present in one line.

[0020]

[Table 1]

[0021]

Industrial Applicability According to the present invention, polybenzazole fiber can be produced at a low cost on an industrial scale.

[Brief description of the drawings]

FIG. 1 is a schematic view of a manufacturing apparatus of the present invention.

[Explanation of symbols]

1. Spinneret, 2. Coagulation bath, 3. Take-up roll, 4.
Suction device, 5. Conveyor 6. Staple cans

Claims (4)

[Claims] 1. A polybenzazole polymer is solution-polymerized in an acid solvent, and the polymerization solution is directly extruded as a spinning dope from a spinneret, and the obtained dope filament is coagulated, washed, and washed.
In the method for producing a polybenzazole filament by drying, the dope filament is continuously subjected to a staple production process without stopping the supply of the spinning dope when a yarn breakage occurs. Production method. 2. The method for producing a polybenzazole fiber according to claim 1, wherein the dope filament is extruded from a plurality of spinnerets, and only the weight in which the yarn breakage occurs is continuously supplied to the yarn making process for staple. 3. In a polybenzazole filament manufacturing apparatus composed of a plurality of spinning spindles, a yarn passing through the coagulating bath is conveyed to a staple can under a trading roll arranged at the outlet of the coagulating bath of each spindle. An apparatus for producing a polybenzazole fiber, characterized in that a conveyor for performing the operation is provided. 4. The apparatus for producing polybenzazole fiber according to claim 3, further comprising a suction device for sucking the yarn that has passed through the coagulation bath between the take-up roll and the conveyor.