JPH03212427A - Production of poly-p-phenylene terephthalamide - Google Patents

Abstract

PURPOSE:To obtain the subject polymer having low hygroscopicity and excellent electrical insulation and useful as fiber, etc., by adding an aromatic monoamine and thionyl chloride to a polymerization system for the polymerization of p- phenylenediamine and terephthaloyl chloride in a solvent. CONSTITUTION:The objective polymer preferably having a polymerization degree corresponding to a logarithmic viscosity of >=3.0, a terminal carboxyl group content of <=20 m-equivalent/kg and a terminal amino group content of <=40 m-equivalent/kg can be produced by adding an aromatic monoamine (e.g. aniline) and thionyl chloride to a polymerization system for the polymerization of p- phenylenediamine and terephthaloyl chloride in a solvent consisting of an N- substituted amide-type solvent (e.g. N-methyl-2-pyrrolidone) and a metal halide (e.g. LiCl).

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). For more details,
The present invention relates to a method for producing PPTA which, when molded into fibers or films, provides a molded product with low moisture absorption, good electrical insulation, and low content of metal impurities.

[Conventional technology]

PPTA obtained by polymerizing terephthalic acid chloride and paraphenylene diamine 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 a reinforcing fiber for materials. On the other hand, conventionally, PPTA films were only soluble in strong acids due to their molecular structure, and in order to form liquid crystals in these solutions, the films obtained by casting were excessively uniaxially oriented and easily cracked. I couldn't.

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).
It is being put into practical use as a film with excellent heat resistance and mechanical strength.

PPTA is usually produced by low-temperature solution polymerization of paraphenylenediamine 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. 35-14399, etc.). It is known that carboxylic acid groups and amino groups exist as terminal groups.

Conventionally, PPTA has mainly been used to make use 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, and heat-resistant adhesive tapes. It is expected to be used as an electrically insulating material with equal heat resistance. However, PPTA has a relatively high hygroscopicity and tends to reduce insulation resistance, especially at high humidity, which is a drawback in this application.

As a method to improve this drawback of PPTA regarding its hygroscopicity, the molecular chain ends are blocked with hydrophobic substituents and the dimensional change due to moisture absorption of the molded product 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 PPTA polymerization system, but it is difficult to reduce the number of carboxylic acid terminal groups below a certain amount. For this reason, it has been difficult to sufficiently improve moisture absorption rate, insulation resistivity under high humidity, and the like.

[Problem to be solved by the invention]

The object of the present invention is to improve the shortcomings of conventional PPTA polymers, such as their hygroscopicity and electrical insulation properties under high humidity, and in addition to excellent heat resistance and mechanical properties, they also have low hygroscopicity and electrical insulation properties under high humidity. P can provide highly insulating films, fibers, etc.
A method for producing PTA polymer is provided.

[Means to solve the problem]

In order to find an effective method for solving the above-mentioned problems, the present inventors have conducted a study on a method for controlling the amount of terminal groups in a polymer, and as a result, they have found that a combination of specific compounds in the polymerization of PPTA has been developed. It was discovered that the amount of carboxylic acid terminal groups could be significantly reduced by adding it, and further studies led to the present invention.

That is, the present invention is characterized in that when paraphenylene diamine and terephthalic acid chloride are polymerized in a solvent system consisting of an N-substituted amide type solvent and a metal halide salt, an aromatic monoamine and thionyl chloride are added to the polymerization system. This is a method for producing polyparaphenylene terephthalamide.

In other words, PPTA is produced by a so-called low-temperature solution polymerization method in which paraphenylene diamine and 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. By adding an aromatic monoamine and thionyl chloride to the polymerization system during production, it is possible to obtain a polymer that provides molded articles with excellent hygroscopicity and electrical insulation properties under high humidity conditions.

The metal halide used in the method of the invention is P
It acts as a solubilization aid for PTA, and includes, for example, alkali metal or alkaline earth metal halides. Specifically, LiCβ, CaCl2,
MgCA2 etc. are used.

Examples of N-substituted amide type solvents include N-methyl-2
-Pyrrolidone, N,N-dimethylacetamide, N-acetyl-2-pyrrolidine, hexamethylphosphoramide, etc. are used, and N-methyl-2-pyrrolidone is particularly preferred due to its low side reactions and safety to the human body. used.

In the method of the present invention, in addition to these components, thionyl chloride and an aromatic monoamine compound are added to the polymerization system. Here, as the aromatic monoamine compound, aniline, o-, m- or p-chloroaniline, o-
, m- or p-toluidine, o-, m-also < is p
- nitroaniline, α- or β-naphthylamine,
Substituted or unsubstituted aromatic monoamine compounds such as 2-13- or 4-biphenylamine are used.

The thionyl chloride and the aromatic monoamine compound 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, it can be added alone without being dissolved in a solvent, but it can also be added as a solution of these compounds and paraphenylenediamine dissolved in a solvent such as an N-substituted amide type solvent. However, thionyl chloride is highly reactive, and depending on the solvent, a rapid reaction accompanied by heat generation may occur, so it is necessary to control the concentration, temperature, etc.

In the method of the present invention, the amount of monomer charged and the amount of aromatic monoamine added can be set as follows.

CPDA+CAM÷2=CTP.・・・・・・
(1) C□/CPDA=0.003~0.03
・・・・・・ (2) CTI/CPDA=0.003
~0.03 ...... (3) However, CPD^ (moβ/l); paraphenylene diamide 20
Ding pc (moβ/1); Terephthalic acid chloride CA
MCmo (1/ (1); aromatic monoamine C
T+(moA/(1); Thionyl chloride, that is, as shown in formula (1), in the polymerization system, it is important to make the number of amino groups and the number of carboxylic acid chloride groups as equal as possible, and thereby Reduce the number of (
can do. In actual production, there are restrictions on measurement accuracy, but as long as it is within a range of about ±0.1% with respect to equation (1), a polymer superior to conventional ones can be obtained. On the other hand, the degree of polymerization changes by changing the amount of aromatic monoamine added to the monomer, but the range of formula (2) is preferably used to obtain a polymer with a practical degree of polymerization.

On the other hand, the amount of thionyl chloride added is preferably within the range of formula (3), and can be changed depending on the amount of impurities in the polymerization system.

The degree of polymerization of PPTA obtained by the method of the present invention varies depending on the amount of monomers, thionyl chloride, and aromatic monoamine added, purity, temperature during polymerization, stirring conditions, etc., but if it is too low, the mechanical properties will deteriorate, so By controlling the logarithmic viscosity (ηinh)
．． It is preferably 0 or more, and more preferably 4.0 or more.

Furthermore, the amount of PPTA carboxylic acid end groups obtained by the method of the present invention is 20 meq/kg or less, preferably 15 meq/kg or less, and the amount of amine end groups is 40 meq/kg.
kg 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. It is thought that this is because the reaction with the amine proceeds further due to thionyl chloride, whereas the reaction does not occur any further.

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 amide type solvent. The concentration of metal halide salt is 1 to 1
The concentration of paraphenylenediamine is preferably 0% by weight, more preferably 1.5 to 7% by weight, and the concentration of paraphenylenediamine is preferably 1 to 8% by weight, and even more preferably 2 to 6% by weight.

After cooling this solution as necessary, terephthalic acid chloride is added and mixed and stirred. Terephthalyl chloride is preferably added in powder or molten form, but 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 it, the temperature can be lowered from -20 to 80℃.
It is preferable to control it within the range of . Furthermore, 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 a powerful stirring device.

The method for adding the aromatic monoamine and thionyl chloride is as follows: (1) A method in which they are dissolved in an N-substituted amide type solvent together with paraphenylenediamine and a metal halide salt before polymerization. (2) A method in which it is added to the polymerization system at the same time as the start of polymerization, (2) A method in which it is added to the polymerization system after the start of polymerization, and thionyl chloride can also be used in combination with (2) terephthalic acid chloride. 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 is important to have an efficient mixing mechanism to promote homogeneous mixing of monomers in the early stage of polymerization and a reaction in a high viscosity or semi-solid state in the late stage of polymerization. It is important to use equipment that has the crosstalk effect necessary for the polymerization to proceed, and multi-stage polymerization using a combination of equipment having respective functions is preferably used. Mainly, first-stage equipment includes, for example, a reaction bed equipped with stirring blades, a continuous mixer that performs continuous mixing using high shear action, and second-stage equipment, such as a single-screw or twin-screw extruder, A kneader mixer, co-kneader, Henschel mixer, etc. can be used.

Thionyl chloride and aromatic monoamine can be added to the polymerization system by injecting 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. be exposed.

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

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

〔Example〕

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

The measurement method was 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 base alkali with hydrochloric acid. The details of these operations can be found in Japanese Unexamined Patent Application Publication No. 1983.
The same method as in JP-46222 was used.

(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=0.2 g/100 ml using the following formula.

r) 1nh= (l B r/C (3) Put about 1 g of the sample into a moisture absorption rate weighing bottle, dry it at 130°C for 6 hours, then measure the weight, and then leave it in an atmosphere of 23° 050% for 48 hours. The weight was measured and calculated from the difference.

(4) Volume resistivity A sample in which a measurement electrode and a card electrode were deposited with aluminum on the surface of the film was left in a 960% atmosphere at 23° C. for 24 hours, and then measured in this state using a super megohmmeter.

Example 1 A jacketed flask with an internal volume of 10j7, which had a monomer inlet, a nitrogen inlet, an additive inlet, and a stirring blade, was
Add N-methyl-2-pyrrolidone 71 and add LiC to this.
118.5 g (2.8 moA) of A was added and stirred for 1 hour to dissolve. Then paraphenylenediamine is added to 302
．． After adding 8 g (2,800 mo I!) and stirring for -h to dissolve, the solution temperature was cooled to -10°C by passing cold brine through the jacket. Further, while continuing to stir, 573.5 g of pulverized terephthalic acid chloride (
2,820 mol) was added, and after 2 minutes, aniline 3.
7 g (0.04 mo 1 ) and thionyl chloride 9
．． 5 g (0.04 moj7) were added in each case as a 1O% N-methyl-2-pyrrolidone solution. After that, 30℃ hot water was passed through the jacket and stirring was continued for 30 minutes.
The resulting polymer mixture was washed with water and dried to obtain a PPTA polymer.

The logarithmic viscosity (ηinh) of this polymer is 4.5; i
'The amount of fulponic acid end groups was 13.5 milliequivalents/kg, and the amount of amino end groups was 25.3 mm equivalents/glare.

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, the glass plate was placed on a hot plate to make the stock solution optically isotropic, and the solution was coagulated with dilute sulfuric acid at a temperature of 0°C and a concentration of 30%.

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 heated at 350°C.
The film was heat-treated for 5 minutes to obtain a film with a thickness of 15 μm. The mechanical properties of the film are strength 27 kg/mIn2, elongation 23%, modulus 950 kg/mm2, and moisture absorption rate 1.
Examples 2 to 4 and Comparative Examples 1 to 2 where the volume resistivity was 2.6 x 101 aΩcm, and Comparative Examples 1 to 2 Experiments were conducted in the same manner as in Example 1 by changing the types and amounts of terephthalic acid chloride, thionyl chloride, and aromatic monoamine. The results are shown in Table 1. Examples 1 to 4 obtained by the method of the present invention have a lower moisture absorption rate and a higher volume resistivity under high humidity than the comparative example.

〔Effect of the invention〕

PPTA produced by the method of the present invention has heat resistance, such as low moisture absorption of fibers and films obtained by molding, high insulation resistivity under high humidity, good long-term heat resistance, and low amount of metal impurities. It has the performance required as an insulating material.

Films include flexible printed wiring boards and LSI
When used as a base material for carrier tapes for mounting, insulating films for motors, transformers, heat-resistant adhesive tapes, etc., and as fibers for woven fabrics for printed wiring boards, etc., compared to those using conventional PPTA. It has excellent performance.

Claims (1)

[Claims] 1. A polyparaphenylene characterized by adding aromatic monoamine and thionyl chloride to the polymerization system when paraphenylenediamine and terephthalic acid chloride are polymerized in a solvent system consisting of an N-substituted amide type solvent and a metal halide salt. Method for producing terephthalamide.