JPS63235520A - Production of ultrafine aromatic polyamide fiber - Google Patents

Abstract

PURPOSE:To obtain the titled fiber outstanding in molecular chain packing characteristics, useful as a resin reinforcer, etc., by dispersing a solvent (e.g. conc. sulfuric acid) solution of aromatic polyamide in a coagulating solvent with each specific solubility parameter and solubility to water to separate the fiber out. CONSTITUTION:The objective ultrafine fiber can be obtained by dispersing (A) a solution consisting of (i) 0.05-3.0wt.% of an aromatic polyamide [e.g., poly(p-phenylene terephthalamide)] and (ii) 99.95-97.0wt.% of at least one kind of solvent selected from >=97wt.% conc. sulfuric acid, chlorosulfuric acid, fluorosulfuric acid, etc. in (B) a coagulating agent with a solubility parameter (deltac) of 11.0-17.0 and solubility to water (s) of >=5wt% (at 20 deg.C) (e.g., dimethylformamide) to separate aromatic polyamide fiber out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing aromatic polyamide ultrafine fibers.

[Conventional technology]

In order to improve the mechanical strength of polymer molded bodies, it is common practice to reinforce them with fibers such as glass fibers and carbon II fibers. Since it is necessary to add a large amount, moldability is poor, and the obtained molded product has a poor surface condition, has anisotropy in strength, and has the disadvantage that it cannot be molded into a film or fiber.

In order to overcome the above-mentioned drawbacks, it has been proposed to use aromatic polyamide fine fibers.

(For example, JP-A-57-61040, JP-A-58
-53953) However, the above-mentioned fine fibers are J, Polymer 5
science.

Polymer Physics Edition,
Vol. 17, 115 (1979), it is prepared by supplying a shear-oriented solution of aromatic polyamide to water or acetone under ultrasonic irradiation and coagulating and precipitating it. The chains are arranged regularly [hereinafter referred to as notesking property]. When X-ray diffracted (200)
The smaller the half-value of the peaks, the more regularly they are arranged. ], the reinforcing effect was small, and the mechanical strength (modulus of elasticity, strain at break) of the obtained molded product was small.

[Problem that the invention seeks to solve]

In view of the above drawbacks, the object of the present invention is to obtain a molded product that can be mixed with a resin and molded into a film or fiber, has a good surface condition, has a large elastic modulus and breaking strain, and has no anisotropy in mechanical strength. An object of the present invention is to provide a method for producing aromatic polyamide ultrafine fibers that can be used.

[Means for solving problems]

The aromatic polyamide used in the present invention is a polyamide whose molecular skeleton is aromatic, and is a polycondensate of aromatic diamine and aromatic dicarboxylic acid halide, such as 0-
Phenylene 7-talamide, m-7 22lene 7-talamide, p-7 22lene-7-talamide, o-phenylene iso-7-talamide, m-phenylene iso-7-talamide, p
-phenylene inotsukuramide, O-phenylene tele 7
talamide, m-phenylene tele 7 talamide, p-phenylene tele 7 talamide, 1.5-s 7 talen 7 talamide, 1.5-s 7 talente 7 talamide, 4,
Aromatic amides such as 4'-di7-di-terephthalamide F, p-phenylene-4゜4'-diphenyldicarbonamide, 1,4-natuthalenthalamide, etc., which are bonded to the benzene wing of the aromatic amide. Homopolymers of compounds in which part of the hydrogen is replaced with halogen, and compounds in which part of the benzene wing of the aromatic amide is replaced with piperazine such as piperazine, 2,5-dimethylpiperazine, 2,5-diethylpiperazine, etc. , copolymers, and poly(p-benzamide), which is a self-assembly of aromatic aminocarboxylic acids and derivatives thereof. In the above aromatic polyamide, the amide bond chains are coaxially or parallelly bonded.
Oriented aromatic polyamides are preferred because they have excellent heat resistance and mechanical strength, and poly(p-phenylene tele-7 talamide) is particularly preferred.

Further, the molecular weight of the aromatic polyamide is preferably 1,000 or more, more preferably 10,000 or more, since mechanical strength decreases as the molecular weight decreases.

In the present invention, the aromatic polyamide is dissolved in a solvent, but if the aromatic polyamide is not uniformly dissolved and uniformly dispersed in the coagulation solvent, the resulting fibers will become thick. One or more solvents selected from the group consisting of % sulfuric acid, chlorosulfuric acid, and fluorosulfuric acid are used.

In addition, the solution contains the above aromatic polyamide 0.05 to 3.0
1! It is formed from 99.95 to 97.0 Jljt%.

In the present invention, the above solution is dispersed in a coagulation solvent to precipitate aromatic polyamide fibers, but if the solubility parameter (δ,) of the coagulation solvent is too large or too small, the precipitated fibers may become thick. %ILON is 17.0 because the backing property of the molecular chain deteriorates, and the solubility (8) in water is 5 wt% or more (20°C) because it becomes difficult for the aromatic polyamide to precipitate as it decreases.

As a coagulating solvent that satisfies the above-mentioned solubility factor (j.
co ), ethanol (δI=110.5=co )
, n-Pro/Nor (Je=1!0.5=co), n
-butano-” (la=IL3, s=7.7), dimethyl sulfoxide (δ*=119, S=ω), dimethylformamide (δ,=1211s=), ethylene glycol (J,=16.3, ), propylene glybur (δ·=14.8, s=), and the like.

The coagulation solvent is preferably used in large excess with respect to the above solution, and it is preferable to stir the coagulation solvent during dispersion.

Any method may be used to blend the ultrafine fibers obtained by the production method of the present invention with resins such as nylon, vinyl chloride resin, ABS resin, etc., such as dry blending, melt blending, side force blending, etc. Examples include a method of casting a solution in which a fraction of the resin and fibers are dissolved in a solvent that dissolves the resin and fibers but not the fibers, and a method of supplying the solution to a coagulating solvent and coagulating it.

In addition, any conventionally known method may be used to obtain molded products such as fibers, films, and sheets from the resulting blend, such as press molding, injection molding, roll molding, extrusion molding, and spinning molding. I can give you a method.

〔Effect of the invention〕

Since the configuration of the uninvented method for producing ultrafine aromatic polyamide fibers is as described above, it is possible to easily produce ultrafine aromatic polyamide fibers with a diameter of 700 μm or less and excellent molecular chain stretchability. can do.

In addition, the resulting blend of aromatic polyamide ultrafine fibers and resin can be easily molded into molded products such as fibers, films, and sheets, and the resulting molded products have good surface conditions and low elastic modulus and breaking strain. Large size, no anisotropy in mechanical strength:
.

In particular, molded articles made of heat-resistant resins such as nylon have excellent heat resistance and are therefore useful in fields such as automobiles, aircraft, electronics, and industrial materials.

〔Example〕

Next, an uninvented embodiment will be described.

Examples 1 to 4, Comparative Example 3.4 Concentrated sulfuric acid (98 wt%) in which poly(p-7 22 lentele 7 talamide) (viscosity average molecular j 140,000) was dissolved in LO weight%
)f! Solution g was supplied to a large excess of the coagulating solvent shown in Table 1 under vigorous stirring to coagulate and precipitate. The precipitate was thoroughly washed with water and then dried to obtain ultrafine fibers. The diameter of the ultrafine fibers was measured using a scanning electron microscope and the results are shown in Table 1.

In addition, ultrafine fibers were compression molded to obtain a sheet with a thickness of about 0.5 wt, and the obtained sheet was measured by X-ray diffraction method.
The value of the half value of the diffraction peak from the (200) plane is the first! !
It was shown to. Moreover, the X-ray diffraction patterns when dimethylformamide was used as a coagulation solvent (Example 2) and when water was used (Comparative Example 3) are shown in FIGS. 1 and 2.

Amorphous nylon (manufactured by Mitsubishi Kasei Corporation, trade name: Glycidylamide TR55) was dissolved in dimethylformamide to obtain a 3% by weight solution of nylon in dimethylformamide. The resulting solution was mixed with 50% of the total amount of ultrafine fibers and nylon.
After the mixture was added and dispersed to a concentration of % by weight, it was supplied to a large excess of water under vigorous stirring to coagulate and precipitate.

After thoroughly washing the precipitate with water, it was fed into a vacuum dryer at 120°C and dried for 24 hours to obtain a polyamide composition.

The obtained polyamide composition was heated at 220°C and 150 kq/c.
Press molding was performed under the conditions of d to obtain a sheet with a thickness of 500 μm.

The obtained sheet was subjected to a tensile test according to JIS K7113 (Danpel No. 2, tensile speed 5, /dai, 25°C), and the results are shown in Table 1.

Comparative Example 1 Amorphous nylon (manufactured by Mitsubishi Kasei Corporation, trade name: Glycidylamide TR55) was press-molded at 220°C and 150 kg/-, and the obtained sheet with a thickness of 500 μm was formed in the same manner as in Example 1. A tensile test was conducted using the following methods, and the results are shown in Table 1.

Comparative example 2 Bo! Concentrated sulfuric acid (98 wt.
%) The solution was fed to a large excess of dimethylformamide under vigorous stirring to cause coagulation and precipitation. The precipitate was sufficiently dried to obtain ultrafine fibers. Using the obtained ultrafine fibers, the fiber diameter and (200) were determined in the same manner as in Example 1.
The half-maximum value of the diffraction peak from the surface was measured and the results are shown in Table 1. Further, a polyamide composition was obtained in the same manner as in Example 1, a sheet was obtained, and a tensile test was performed, and the results were reported in the first example.
Shown in the table.

Comparative Example 5 Bo! 1 (concentrated sulfuric acid (98 wt%) in which 10 wt% of p-phenylene terephthalamide (viscosity average molecular weight 40,000) was dissolved
The solution was supplied to a large excess of water that was being irradiated with ultrasonic waves to coagulate and precipitate. The precipitate was sufficiently dried to obtain ultrafine fibers. Using the obtained ultrafine fibers, the diameter of the fibers and the mid-half value of the diffraction peak from the (200) plane were measured in the same manner as in Example 1, and the results are shown at 12%. Further, a polyamide composition was obtained in the same manner as in Example 1, and then a sheet was obtained and a tensile test was performed, and the results are shown in Table 1.

(Margin below)

[Brief explanation of the drawing]

FIG. 1 is an X-ray diffraction diagram of the ultrafine fiber obtained in Example 2, and FIG. 2 is an X-ray diffraction diagram of the ultrafine fiber obtained in Comparative Example 3.

Claims (2)

[Claims] 1. Aromatic polyamide 0.05-3.0% by weight and 97w
t% or more of one or more solvents selected from the group consisting of concentrated sulfuric acid, chlorosulfuric acid, and fluorosulfuric acid99.9
A solution consisting of 5 to 97.0% by weight has a solubility parameter (δ_0) of 11.0 to 17.0 and a solubility in water (
A method for producing ultrafine aromatic polyamide fibers, characterized in that aromatic polyamide ultrafine fibers are precipitated by dispersing them in a coagulation solvent in which s) is 5 wt% or more (at 20° C.). 2. The method for producing aromatic polyamide ultrafine fibers according to claim 1, wherein the aromatic polyamide is poly(p-phenylene terephthalamide).