JPH03259921A - Production of poly-p-phenyleneterephthalamide - Google Patents

Abstract

PURPOSE:To produce a poly-p-phenyleneterephthalamide of lowered hygroscopicity by reacting p-phenylenediamine with terephthaloyl chloride in the presence of three specified compounds in an N-substituted amide solvent in which a metal halide is dissolved. CONSTITUTION:A metal halide (e.g. LiCl) is dissolved in an N-substituted amide solvent (e.g. N-methyl-2-pyrrolidone) to obtain a solvent. Separately, 0.1-5mol, based on the monomer to be reacted, carbodiimide compound as a polymerizing agent (e.g. dicyclohexylcarbodiimide) is mixed with 0.2-1.5mol.%, based on the monomer to be reacted, monoamine (e.g. aniline) and/or monocarboxylic acid chloride (e.g. benzoyl chloride) as a terminating agent to obtain a mixture. p-Phenylenediamine is made to react with terephthaloyl chloride in the presence of the obtained mixture in the solvent D to obtain a poly-p- phenyleneterephthalamide with the content of 20meq./kg of a terminal carboxylic group.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing polyparaphenylene terephthalamide (hereinafter abbreviated as PPTA).

More specifically, when the bottom shape is formed on fibers or films,
The present invention relates to a method for producing PPTA that has a low moisture absorption rate, good electrical insulation, and a low content of metal impurities.

[Conventional technology]

PPTA obtained by polymerizing terephthalic acid chloride and paraphenylenediamine is a polymer with a rigid molecular skeleton, and the fiber obtained by liquid crystal spinning from a sulfuric acid solution has extremely high mechanical properties and is useful for tire cords and fiber-reinforced composites. Practical use is progressing as reinforcing fiber for industrial applications.

On the other hand, conventionally, PPTA film was only soluble in strong acids due to its molecular structure, and in order to form liquid crystals in such solutions, the film obtained by casting was excessively uniaxially oriented and easily cracked. However, recently, a technique to obtain an isotropic film by relaxing the liquid crystal state has been developed (for example, Japanese Patent Publication No. 17886/1986), and it has been put into practical use as a film with excellent heat resistance and mechanical strength. It is becoming more and more popular.

PPTA is usually produced by low-temperature solution polymerization of para-phenylenediamine and terephthalic acid chloride in a solvent system consisting of an N-substituted amide type solvent and a metal halide salt (Japanese Patent Publication No. 3544399, etc.), and the end of the polymer is It is known that carboxylic acid groups and acino groups exist as groups.

Traditionally, PPTA has been mainly used to take advantage of its mechanical properties, but as electronics progresses and electrical equipment becomes smaller and more integrated, films and fibers are used for printed wiring boards, electrical insulation films, heat-resistant adhesive tapes, etc. It is expected to be used as a heat-resistant electrical insulating material. However, PPTA has a relatively high hygroscopicity and tends to reduce insulation resistance, especially at high humidity, which is a problem in this application.

As a method to improve this problem regarding the hygroscopicity of PPTA, the molecular chain ends are blocked with hydrophobic substituents and the dimensional change due to moisture absorption of molded products is prevented by using a polymer with a reduced amount of amine and carboxylic acid end groups. It is described in Japanese Unexamined Patent Application Publication No. 63-46222 that the size is smaller. This polymer with few terminal groups is synthesized by adding monofunctional compounds such as monoamines and monocarboxylic acid chlorides to the polymerization system of PPTA, but it is produced by the reaction between a small amount of water present in the polymerization system and acid chloride groups. It has been difficult to reduce the number of carboxylic acid terminal groups below a certain amount, and therefore it has been difficult to sufficiently improve moisture absorption, insulation resistivity under high humidity, etc.

[Problem to be solved by the invention]

The object of the present invention is to improve the problems of conventional PPTA polymers, such as their hygroscopicity and electrical insulation properties under high humidity conditions. The object of the present invention is to provide a method for producing a PPTA polymer by which highly insulating films, fibers, etc. can be obtained.

[Means for Solving the Problems] In order to find an effective method for solving the above problems, the inventors of the present invention, in particular, conducted studies on methods for controlling the amount of terminal groups in polymers, and found that PPTA In some cases, the inventors discovered that the amount of carboxylic acid terminal groups can be significantly reduced by adding a combination of specific compounds, and further studies led to the present invention.

That is, in the present invention, when polymerizing paraphenylene diamine and terephthalic acid chloride in a solvent system consisting of an N-substituted amide type solvent and a metal halide salt, a carbodiimide compound and a monoamine and/or a monocarboxylic acid chloride are added to the polymerization system. 1. A method for producing polyparaphenylene terephthalamide, characterized by:

In other words, the present invention is a so-called low-temperature solution in which paraphenylene cyanide and a metal halide salt are dissolved in an N-substituted amide solvent, and then this solution and terephthalic acid chloride are mixed with stirring to perform a polymerization reaction. P by polymerization method
By adding a carboxylic acid compound and a monoamine and/or a monocarboxylic acid chloride to the polymerization system when producing PTA, a polymer is provided that allows molded products with excellent hygroscopicity and electrical insulation properties under high humidity to be obtained. It is characterized by:

The metal halide compound used in the present invention acts as a solubilization aid for PPTA, and examples include halides of alkali metals or alkaline earth metals, and specific examples include LICII CaC1z and MgCh.

As the N-substituted adduct solvent, for example, N-methyl-2
-Pyrrolidone, N,N-dimethylacetamide, N-acetyl-2-pyrrolidine, hexamethylphosphoramide, etc. are used, and N-methyl-2-pyrrolidone is especially used because of its low side reactions and safety to the human body. Preferably used.

In addition to these fractions, the present invention requires the addition of a carbodiimide compound and a monoamine and/or monocarboxylic acid chloride to the polymerization system.

Here, the carbodiimide compound means a compound having a carboxyd bond (-N=C=N-) in the molecule, and acts as a condensing agent in polymerization, and includes dicyclohexylcarbosiimide, diphenyl Carbodiimide, ethyl-3(dimethylaminopropyl)carbodiimide, 1-cyclohexyl-3-(3-morpholinoethyl)carbodiimide, and the like are used. The carbodiimide compound is added in an amount usually in the range of 0.1 to 5 mol%, preferably 0.5 to 1.5 mol%, based on the monomer.

Monoamine and monocarboxylic acid chloride are added as end-blocking agents, and one or both of them can be used. Monoamine compounds include aniline, o-, m- or p-chloroaniline, o-m-
or P-) luidine, o-, m- or p-nitroaniline, α- or β-naphthylane, 2-2
3- or 4-biphenylamine or the like is used. Further, as the monocarboxylic acid chloride, benzoyl chloride, o-, m- or P-)luoyl chloride, propionyl chloride, etc. are used. The amount of the terminal capping agent to be charged is preferably in the range of usually 0.2 to 1.5 mol% based on the monomer, and the number of moles of amino groups and acid chloride groups in the polymerization system of the monomer and the terminal capping agent is approximately It is preferable to set them to be equal.

The carbodiimide compound, monoamine, and monocarboxylic acid chloride can be added to the paraphenylenediamine solution before polymerization, or can be added to the polymerization system after the start of polymerization. Further, as for the addition method, they can be added alone to a solvent without being dissolved, but they can also be added as a solution of these compounds and paraphenylene cyagon dissolved in a solvent, such as an N-substituted amide type solvent. However, since carbodiimide compounds are highly reactive and rapid reactions may occur depending on the solvent, it is necessary to control the concentration, temperature, etc.

The degree of polymerization of PPTA obtained by the method of the present invention varies depending on the amount of monomer, carbodiimide compound, monocarboxylic acid chloride, purity, temperature during polymerization, stirring conditions, etc., but if it is too low, the mechanical properties It is preferable to control these to make the logarithmic viscosity ηinh 3.0 or more, and 4.0
It is more preferable to set it as above.

Furthermore, the PPTA obtained by the method of the present invention has a carboxylic acid terminal group content of 20. equivalents/kg or less, preferably 15 milliequivalents/kg or less, and the amount of amine end groups is 40 milliequivalents/k
g or less.

The production method of the present invention is characterized in that the amount of carboxylic acid terminal groups can be reduced compared to conventional methods. The reason for this is thought to be that the carboxylic acid group produced by the reaction of terephthalic acid chloride with impurity water does not react any further in a normal method, but the reaction with the amine further progresses with the addition of a carbodiimide compound.

Since the heat resistance of PPTA molded products is significantly lowered if carboxylic acid terminal groups are present, neutralization with sodium hydroxide or the like is usually performed in the fiber or film manufacturing process. As a result, the terminal becomes a carboxylic acid salt, which is thought to reduce hygroscopicity and electrical insulation under high humidity conditions.

In contrast, in the method of the present invention, it is possible to reduce the amount of carboxylic acid terminal groups, so it is thought that these performances can be improved.

Next, the manufacturing method of the present invention will be explained in more detail.

In the method of the present invention, first, a solution is prepared by dissolving paraphenylenediamine and a metal halide salt in an N-substituted oxide solvent. The concentration of metal halide salt is 1 to 10% by weight.
is preferable, 1.5 to 7% by weight is more preferable, and the concentration of paraphenylenediamine is preferably 1 to 8% by weight, 2
-6% by weight is more preferred.

After cooling this solution as necessary, terephthalic acid chloride is added and mixed and stirred. Terephthalic acid chloride is preferably added in powder or molten state, but
It can also be added as a solution in an N-substituted amide solvent.

The polymerization reaction is accompanied by exothermic heat, and the temperature of the system rises in a short period of time, but by adjusting the initial temperature and cooling, the temperature can be reduced to -20 to 80°.
It is preferable to control it within the range of C. Further, as the degree of polymerization increases, the viscosity of the system increases and further solidification of the polymer occurs, but in order to obtain a high degree of polymerization, it is preferable to continue stirring even after solidification using strong stirring.

The methods for adding the carbodiimide compound, monoamine, and monocarboxylic acid chloride include: (1) dissolving them in an N-substituted amide type solvent together with phenylene diamine and metal halide salt before polymerization; (2) adding them to the polymerization system at the same time as the start of polymerization; (2) A method of adding it to the polymerization system after the start of polymerization can be used.

Among these methods, from the viewpoint of the performance of the resulting polymer, method (2) in which the compound is added to the polymerization system after the initiation of polymerization is preferably used.

The polymerization reactor may be either a batch type or a continuous type, but it must have an efficient mixing mechanism to promote homogeneous mixing between monomers in the early stage of polymerization, and a high viscosity or semi-solid state in the late stage of polymerization. It is important to use equipment that has the necessary crosstalk effect, and multi-stage polymerization using a combination of equipment that has each function is preferably used.

Mainly, the first-stage equipment includes a reaction bed equipped with stirring blades, a continuous mixer that performs continuous mixing using high shear action, and the second-stage equipment includes a single-screw or twin-screw extruder, A kneader mixer, a co-kneader Henschel mixer, etc. can be used.

A method for adding carbodiimide compounds, monoamines, and monocarboxylic acid chlorides to the polymerization system is to inject these compounds or a solution dissolved in an appropriate solvent through a nozzle installed in the polymerization apparatus while metering the mixture using a plunger pump or the like. done in a manner.

The mixture containing the polymer produced in this way is washed with water, acetone, methanol, etc., neutralized with sodium hydroxide, calcium hydroxide, etc., then separated in a furnace or centrifuged, and dried. of PPTA polymer is obtained.

Furthermore, a dope prepared by redissolving this polymer in a solvent such as sulfuric acid can be shaped into fibers, films, fibrids, etc. by wet, dry, or dry-jet-wet molding methods.

〔Example〕

The present invention will be explained in more detail with reference to Examples.

The physical properties were measured as follows.

(1) Quantification of terminal groups The amine terminal groups were determined by measuring the absorbance at a wavelength of 430 nm of a compound produced by reacting with 1-fluoro-2,4-dinitrobenzene.

On the other hand, the carboxylic acid terminal group was determined by neutralizing with sodium hydroxide and back titrating the remaining alkali with hydrochloric acid. The details of these operations were carried out in the same manner as in JP-A-6346222.

(2) Logarithmic viscosity ηinh Calculated from the relative viscosity ηr determined at 35°C using an Ostwald viscosity tube for a 99.5% sulfuric acid solution at a concentration C=0.2g/100M1 using the following formula.

η1nh=1nηr/C (3) Put about 1 g of the sample into a moisture absorption rate measurement bottle, dry it at 130″C for 6 hours, measure the weight, and dry it in a 50% air conditioner at 23°C for 48 hours.
The weight was measured after being left for a period of time, and the weight was calculated from the difference.

(4) Measurement electrodes and guard electrodes were deposited with aluminum on the surface of the volume resistivity film.
After standing for a period of time, measurements were taken using a super megohmmeter in this state.

Example 1 N was added to a jacketed flask with an internal volume of 10 f, which had a seven-layer inlet, a nitrogen inlet, an additive inlet, and a stirring blade.
- Add methyl-2-pyrrolidone 71 and add LiCl
118.5 g (2.8 mof) was added and stirred for 1 hour to dissolve. Then add phenylene diamine to 302.8
g (2,800 mof) was added and after stirring for - hours to dissolve, the solution temperature was cooled to -10°C by passing cold brine through the jacket. While continuing to stir, 573.5% (2,820%) of terephthalic acid chloride was finely powdered.
mol ) and added 3.7 g (0
,04mo E ) and 6-2 g of dicyclohexylcarbodiimide (0,03mof ) each in 10% N
-Methyl-2-pyrrolidone solution. After that, hot water at 30°C was passed through the jacket, stirring was continued for 30 minutes, and the resulting polymer mixture was washed with water and dried, and the PPTA
A polymer was obtained.

The ηinh of this polymer is 4.7, the carboxylic acid end volume is 14.9 meq/kg, and the amino end group amount is 22.
It was 8 milliequivalents/kg.

Next, a film was formed using this polymer in the following manner.

The polymer was dissolved in concentrated sulfuric acid with a concentration of 99.5% to prepare a stock solution with a polymer concentration of 12%. This stock solution was cast onto a glass plate using a doctor knife, and then the glass plate was placed on a hot plate to make it optically isotropic.
It was coagulated with concentrated dilute sulfuric acid. After neutralizing with 1% NaOH and washing with water, it was fixed in a stainless steel metal frame, dried at 200°C for 10 minutes, and then heat-treated at 350°C for 5 minutes to obtain a 15μ-thick film. The mechanical properties of the film are strength: 29) cg/-1 elongation: 21%, modulus: 925
kg/-1 moisture absorption rate 2.2%, volume resistivity 5. lX10”
It was Ω・Bi.

Examples 2 to 4, Comparative Examples 1 to 2 Table 1 shows the results of experiments conducted in the same manner as in Example 1, using aniline and benzoyl chloride as end-blocking agents and varying their amounts. Example 2 according to the method of the present invention
-4 have lower moisture absorption rates and higher volume resistivities at high temperatures than the comparative examples.

[Margin below] 〔Effect of the invention〕

The method of the present invention produces PPTA that has the performance required for heat-resistant insulating materials, such as low moisture absorption, high insulation resistivity under high humidity, good long-term heat resistance, and low amount of metal impurities. can do. The film obtained by molding this PPTA can be used as a base material for flexible printed wiring boards, carrier tapes for LSI mounting, insulation films for motor transformers, heat-resistant adhesive tapes, etc.
Furthermore, when the fiber is used in woven fabrics for printed wiring boards, etc., it has superior performance compared to those using conventional PPTA.

Claims (1)

[Claims] 1. When polymerizing paraphenylenediamine and terephthalic acid chloride in a solvent system consisting of an N-substituted amide type solvent and a metal halide salt, a carbodiimide compound and a monoamine and/or monocarboxylic acid chloride are added to the polymerization system. A method for producing polyparaphenylene terephthalamide.