JPS62162013A - Production of pulp-like short fiber of poly(p-phenylene terephthalamide) - Google Patents

Abstract

PURPOSE:In a polar amide solvent containing an alkali metal chloride, terephthaloyl chloride is added stepwise to p-phenylenediamine to effect polycondensation reaction, then a precipitating agent is added, and the precipitate is crushed to give the titled fiber of high processability, giving high-duration paper. CONSTITUTION:The primary reaction between 1mol of p-phenylenediamine and 0.5-0.9mol of terephthaloyl chloride is carried out in a polar amide solvent containing 2-5wt% of an alkali or alkaline earth metal chloride to form oligomers of 1.5-15 polymerization degree. Then, the remaining terephthaloyl chloride and 3-50wt%, based on the amide solvent, of pyridine are simultaneously or step by step added to the reaction mixture under stirring to effect the secondary reaction to give a composition containing a polymer of high polymerization degree. Then, a precipitating agent is added to the product, crushed to give the objective short fibers of 30-45Angstrom crystal size.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing high quality pulp-like short fibers consisting essentially of poly(P-phenylene terephthalamide).

[Prior Art] Pulp-like short fibers of poly(P-phenylene terephthalamide) are produced by spinning an optically anisotropic solution of poly(P-phenylene terephthalamide), which has molecular orientation. P-phenylene terephthalamide) fibers are crushed by applying mechanical shearing force such as beating, and the fibers are fibrillated (see Japanese Patent Publication No. 59-603).

This method not only requires a spinning process to produce -tan fibers, but also a process of cutting the spun fibers into appropriate lengths to make them easier to beat, and a process of beating the cut staple fibers. Since it is necessary, it cannot necessarily be said that it is economically advantageous.

Recently, as a method to solve the above-mentioned problems seen in the conventional method for producing pulp-like short fibers, a method has been developed in which paraphenylenediamine and terephthalic acid chloride are combined with 3 to 50% by weight of pyridine and 97 to 50% by weight of an amide solvent. Furthermore, if necessary, an alkali metal or alkaline earth metal chloride 1
React in a polymerization solvent system to which ~5% by weight is added, stir during the polymerization reaction to form a solid reaction mixture with molecular orientation, and beat this to obtain pulp-like short fibers. A method has been proposed
(See Publication No. 801).

This method eliminates the need for a spinning process, making it possible to produce pulp-like short fibers more economically than conventional methods. The problem is that the degree of polymerization of the poly(P-phenylene terephthalamide) to be formed is difficult to increase, and the degree of polymerization of the poly(P-phenylene terephthalamide) obtained varies widely, making it impossible to obtain a product of uniform quality. be. In addition, the special public corporation Showa 6
Pulp-like short fibers with a high degree of crystallinity and a large crystal size as described in Publication No. 0-56801 have poor processability when made into paper, and the durability of the obtained paper is also insufficient. It turns out.

[Object of the Invention] The first object of the present invention is to overcome the drawbacks of the above-mentioned methods and to provide a pulp-like shortened product of poly(P-7 ethylene terephthalamide) of economically good quality. An object of the present invention is to provide a method for industrially manufacturing fibers. Another object of the present invention is to provide a method for producing pulp-like short fibers of poly(P-phenylene terephthalamide) that can be formed into paper with excellent processability and good durability. It is in.

[Structure of the Invention] The above-mentioned object, according to the present invention, is based on the amount of terephthalic acid chloride of 0.5 to 0.
The first reaction is carried out in a polar amide solvent containing 2 to 5% by weight of an alkali metal or alkaline earth metal to form an oligomer with an average degree of polymerization of 1.5 to 15. Next, 3 to 30% by weight of pyridine based on the weight of the remaining terephthalic acid chloride and polar amide solvent is simultaneously or sequentially added to the polymerization system and stirred to perform a secondary reaction. A composition containing poly(P-phenylene terephthalamide) having a polymerization degree is formed, and then a precipitant is added to the composition and pulverized to obtain pulp-like short fibers with a crystal size of 30 to 45 people. This is achieved by

In the method of the present invention, the polymerization of poly(P-phenylene terephthalamide) is carried out using novel 2
This is carried out by a step polymerization method, and then pulp-like short fibers are produced directly from the polymer composition by the method described below (/9).

(1') First-stage reaction First, in the first-stage reaction, P-phenylenediamine and terephthalic acid chloride are mixed with 0.5 to 0.9 terephthalic acid chloride per mole of P-phenylenediamine.
mol, preferably 0.55 to 0.8 mol, particularly preferably 0.6 to 0.8 mol, in the polymerization solvent,
- Perform low-temperature solution polymerization with a large excess of phenylenediamine. As the polymerization solvent system, a system in which an alkali metal chloride and/or an alkaline earth metal chloride is added to a polar amide solvent is used. As the polar amide solvent, N.

Preferred are N'-dimethylformamide, N,N'-dimethylacetamide, N-methyl-2-pyrrolidone, tetramethylurea and the like. Furthermore, the effect of the present invention may be further improved by adding a small amount of a non-solvent such as tetrahydrofuran, methylene chloride, methyl ethyl ketone, etc. to the polar amide solvent.

Moreover, lithium chloride is preferable as the alkali metal chloride, and calcium chloride is preferable as the alkaline earth metal chloride. The content of the chloride in the polar amide solvent is preferably 2 to 5% by weight based on the total weight of the solvent system.

Japanese Patent Publication No. 60-48537 discloses that poly(P-phenylene terephthalamide) is polymerized in a polymerization solvent system in which 5% by weight or more of calcium chloride is added to a polar amide solvent such as N-methylpyrrolidone. is stated, but
In the present invention, there is no need to use a solvent system containing such a large amount of chloride, and 5% by weight or less of chloride is sufficient. A large amount of chloride in the solvent system is undesirable since there is a risk that a considerable amount of chloride will be contained in the final pulp-like short fibers.

Furthermore, JP-A-52-124050 describes the use of an amide solvent-pyridine-chloride system as the polymerization solvent system; When pyridine is included, the polymerization reaction proceeds too rapidly, resulting in only polymers with extremely large variations in the degree of polymerization.

In the first stage reaction of the method of the present invention, the diamine component (P-phenylenediamine) and the dicarboxylic acid component (terephthalic acid chloride) are charged into the reaction system at a ratio (mole ratio) of 1 to 0.5 of the latter. ~0.9 (preferably 0
．． 55 to 0.8, more preferred [however, n=1 to 15. Preferably, oligomers represented by [2 to 9] are obtained.

Here, if the molar ratio is smaller than 0.5, almost no oligomer will be produced, and if it is larger than 0.9, the reaction will proceed too much and the reaction system will solidify, resulting in a predetermined degree of polymerization. It is difficult to form an oligomer.

The reaction initiation temperature should be 0-30℃, and 0-20℃
is preferably used. Usually, the first reaction is carried out by dissolving a predetermined amount of P-phenylenediamine in the solvent system, adjusting the temperature to a predetermined reaction initiation temperature, and then adding terephthalic acid chloride and stirring. The amount of each monomer component in the polymerization solvent system is preferably adjusted so that the polymer concentration in the final composition after the polymerization reaction (after the second reaction) is 4 to 8% by weight. Further, the reaction time of the first reaction is preferably about 5 to 60 minutes.

In addition, in carrying out the first reaction, a part of the P-phenylenediamine (for example, 10 mol % or less) is added to other aromatic diamines, such as m-phenylenediamine, sphenylenediamine, 3,4-diamino diphenyl ether, 4
．． 4'-diaminodiphenyl ether, etc. can be substituted, and a portion (for example, 10 mol% or less) of terephthalic acid chloride can be replaced with other aromatic dicarboxylic acids, such as isophthalic acid chloride, 2,6-natutaledicarboxylic acid chloride, etc. You can also replace it with

After the first reaction is completed, it is preferable to introduce anhydrous ammonia gas into the reaction system to neutralize H(J) produced by the reaction.

(01 Second reaction According to the present invention, after obtaining a predetermined oligomer solution by the first reaction as described above, the remaining terephthalic acid chloride, that is, P-phenylenediamine and substantially Terephthalic acid chloride and pyridine are added in equimolar amounts simultaneously or sequentially, and the system is stirred to carry out the second reaction.

The amount of pyridine added should be 3 to 50% by weight, preferably 5 to 30%, based on the weight of the polar amide solvent. Moreover, the timing of adding pyridine is preferably after the addition of terephthalic acid chloride, and it is especially preferable to add pyridine within 10 to 60 seconds after the completion of addition of terephthalic acid chloride. If the addition of pyridine is too slow, the effects of the present invention cannot be obtained.

Stirring is preferably performed by applying a strong shearing force to the polymerization system (secondary reaction system), and in some cases, it is appropriate to use a kneader or the like.

This secondary reaction is preferably carried out at 10 to 50°C,
The reaction time may be about 1 to 5 hours, but the actual stirring time may be about 2 to 5 minutes, and when the reaction system solidifies, the stirring may be stopped and left standing for 1 to 5 hours.

In addition, the latter half of the reaction may be strongly kneaded using a kneader or the like.

＼) Pulp-like short fibers The polymerized system after the second reaction is gelled and almost solid, but when a precipitant is added to it and stirred and pulverized, the polymerized system becomes fine fibrils. becomes pulp-like short fibers with

As the precipitant, water, lower alcohol, acetone, or lower alkyl halide such as methylene chloride is used. These may be used alone or in combination of two or more.

The pulp-like short fibers thus obtained have a length of 50
It has many fine fibrils with a size of 0 to 5000 μm.

The pulp-like short fibers have a crystallinity of 50% or more by X-ray diffraction and a crystal size within the range of 30 to 45 crystals, compared to the pulp-like short fibers described in Japanese Patent Publication No. 60-56801. It is characterized by a very small crystal size. Further, the intrinsic viscosity IV of poly(P-phenylene terephthalamide) constituting the pulp-like short fibers is usually 6.0.
In addition, the variation in the intrinsic viscosity of the polymer is very small.

[Effects of the Invention] The pulp-like short fibers of poly(P-phenylene terephthalamide) obtained by the method of the present invention have high strength and quality stability because the polymerization degree of the constituent polymer is high and the variation in the polymerization degree is small as described above. In addition, the crystal size is 3
Due to the number of 0 to 45 people, it has the advantage that it has excellent processability when it is made into paper, such as calender processing, embossing, etc., and the paper has good durability.

In addition, the reaction control in the polymerization reaction (first reaction and second reaction) is easy and the process stability is good. In addition, just by adding a precipitant to the composition after the polymerization reaction and stirring and pulverizing it, a good process can be achieved. Since it becomes pulp-like short fibers, it is extremely easy to manufacture.

The pulp-like short fibers obtained by the method of the present invention are mixed with wholly aromatic polyamide fibers and used for electrical insulation.

It can be effectively used as a paper-like sheet for honeycomb cores or as a friction material by mixing it with inorganic fibers.

[Method of measuring indicators] Next, a method for measuring each index referred to in the present invention will be explained.

(ω Intrinsic viscosity (IV) concentrated sulfuric acid (98%) + 2804) 0.
It is determined from the value measured at 30°C for a solution containing 5 g of polymer.

<b+ Crystallinity By normal X-ray method.

<c> Crystal size According to the method for measuring the "apparent microcrystal size" described in Japanese Patent Publication No. 59-14567.

[Example] Next, the present invention will be explained in more detail with reference to Examples.

Example 1. Comparative Examples 1 and 2 The inside of a separable flask with a volume of 300 d, which has a stirring blade rotating at high speed, an inlet and an inlet for dry nitrogen, and a raw material inlet, was thoroughly dried by flowing nitrogen while heating from the outside. N-methyl-2-pyrrolidone (NMP) was prepared by dissolving calcium chloride in molecular sieves to a concentration of 4% by weight.
) After drying 120 m, it was placed in the above flask.

Next, P-phenylenediamine (PPDA) was dissolved in the above NMP solution in an amount of 6 g per 100 d of solvent, and after cooling to 0°C, terephthalic acid chloride (TPO) powder was added per mole of PPDA while stirring. 0.67 mol was added to carry out the first reaction, and after the reaction was completed, anhydrous NH4 gas was blown into the reaction system to neutralize HCj generated in the first reaction. The oligomer obtained by this first reaction had an average degree of polymerization of 2.5.

Subsequently, this oligomer solution was added with TPO of the amount shown in Table 1.
The powder was added, and 30 seconds later, an amount of pyridine not shown in Table 1 was added, and the mixture was vigorously stirred and mixed to carry out the first reaction. After stirring and mixing, the polymerization reaction system became viscous and became solid after about 3 minutes, so stirring was stopped and the reaction system was left standing for 3 hours. When water was added to the reaction system and strongly stirred, it became pulpy. Short fibers were produced.

Regarding the pulp-like short fibers thus obtained, the intrinsic viscosity (IVY) of the polymer, the size of the pulp-like IM@, the degree of crystallinity, the crystal size, etc. were measured.

Then each pulpy short! Poly(m-phenylene isophthalamide) with a cut length of 5 # for 50 parts by weight of l fiber!
50 parts by weight of i-fiber (registered trademark "UNEX") was mixed and formed into a sheet, which was calendered to form a paper-like product. The papermaking properties were good, and the properties of the obtained paper were also excellent.

For comparison, a case in which PPDA and TOC were charged in equimolar amounts in the first reaction using the same method as in Example 1 (Comparative Example 1) and a case in which pyridine was not added in the second reaction (Comparative Example) We also conducted an experiment regarding 2).

The experimental conditions for each experiment are shown in Table 1, and the experimental results are shown in Table 2.

From these Tables 1 and 2, it can be seen that in the method of the present invention (Example 1), the IV of the pulp-like short fibers is high, and the paper-making properties and physical properties of the paper-like products made are excellent. .

(Margin below) Table 1: Experimental conditions Table 2: Experimental results Procedural amendment June 72, 1986

Claims (6)

[Claims] (1) Both of the above components are combined with an alkali metal or alkaline earth metal in a proportion of 2 to 5% by weight of terephthalic acid chloride at a ratio of 0.5 to 0.9 mol to 1 mol of P-phenylenediamine.
A first reaction is carried out in the polar amide solvent containing the oligomer to form an oligomer with an average degree of polymerization of 1.5 to 15, and then 3 to 50% by weight based on the weight of the remaining terephthalic acid chloride and the polar amide solvent. % of pyridine is simultaneously or sequentially added to the polymerization system and stirred to carry out a secondary reaction to form a composition containing poly(P-phenylene terephthalamide) with a high degree of polymerization, and then the composition A method for producing pulp-like short fibers consisting essentially of poly(P-phenylene terephthalamide), characterized in that pulp-like short fibers having a crystal size of 30 to 45 Å are obtained by adding a precipitant to the mixture and pulverizing the same. . (2) The production method according to claim (1), wherein the polymerization initiation temperature of the first reaction is 0 to 30°C. (3) Claim (1) or (2) states that after the completion of the first reaction, anhydrous ammonia gas is introduced into the reaction system to neutralize and remove HCl generated in the first reaction. manufacturing method. (4) The production method according to claim (1), wherein in the second reaction, pyridine is added within about 1 minute after the completion of the addition of terephthalic acid chloride. (5) The polymer concentration in the composition after the second reaction is 4 to 8.
The manufacturing method according to claim (1) or (4), expressed as weight %. (6) As a precipitant, water, lower alcohol, acetone,
The manufacturing method according to claim (1), wherein at least one liquid selected from lower alkyl halides is used.