JPH02127429A - Pyrazine ring-containing aromatic polyamide and production thereof - Google Patents

Abstract

PURPOSE:To obtain the title polyamide having a specific recurring unit and specific intrinsic viscosity as well as high modulus and low hygroscopic properties by subjecting a specific para-substituted aromatic dicarboxylic acid chloride to solution polymerization reaction with a specific para-substituted aromatic diamine in an amide based solvent. CONSTITUTION:A para-substituted aromatic diamine expressed by formula I and/or formula II (R1, R2, R3 and R4 are H or monovalent substituent groups; X is Cl, Br, etc.) is subjected to solution polymerization with a para-substituted aromatic diamine expressed by formula III and/or formula IV (R5, R6, R7 and R8 are H or monovalent substituent groups) at substantially equimolar amount and in a ratio being 0.1-1.0 in sum of molar fraction of a halide expressed by formula I and diamine expressed by formula III in an amide based solvent to provide the aimed polyamide having recurring unit expressed by formula V (Ar1 and Ar2 are bivalent aromatic cyclic groups expressed by formula VI and formula VII), being 0.1-1 in molar fraction of a group expressed by formula VI to wholly aromatic cyclic group and having >=2.0 intrinsic viscosity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pyrazine ring-containing aromatic polyamide and a method for producing the same.

More specifically, the present invention relates to a novel para-oriented aromatic polyamide having a pyrazine ring and a method for producing the same.

[Conventional technology and its problems]

Para-oriented aromatic polyamides, represented by polyparaphenylene terephthalamide (hereinafter referred to as PPTA), have excellent heat resistance, chemical resistance, and mechanical properties, and are useful for fibers,
It is extremely useful as a film or fibrid, and is one of the polymers that has received particular attention in recent years.

In addition, we investigated the structure of the carboxylic acid chloride or diamine used as the monomer of PPTA, and by introducing a copolymer component, when formed into fibers etc., PPTA
It has been widely studied to impart higher strength and modulus of elasticity compared to that of steel, as well as to improve and impart various other properties.

For example, Japanese Patent Publication No. 55-11763, Japanese Patent Publication No. 574
No. 9205 discloses that a polymer obtained by introducing a rigid copolymer component is used, and by liquid crystal spinning,
It is disclosed that fibers with higher modulus than PPTA can be obtained.

These polymers are mainly produced using the corresponding aromatic diamine and aromatic dicarboxylic acid halide as raw materials in a solvent containing an inorganic salt by a low temperature polymerization method etc. (Japanese Patent Publication No. 60-48537, (Special Publication No. 60-55538, etc.).

By molding the para-oriented aromatic polyamide as described above, molded articles such as fibers and films having excellent heat resistance, chemical resistance, and mechanical properties can be obtained.

However, such para-oriented aromatic polyamides have the disadvantage of high hygroscopicity due to their amide bonds. For this reason, for example, when these fibers are used as a composite with a resin, problems such as minute cracks occur due to the difference in dimensional change from the matrix resin due to moisture absorption.

In addition, the film also suffers from the problem that its electrical characteristics change significantly and its dimensions change significantly due to moisture absorption.

In addition, these aromatic polyamides are often used as reinforcing materials, for example in the form of fibers or films, but in this case, in order to improve the mechanical properties of the resulting molded product, it is necessary to have a high elastic modulus. This is strongly required.

In conventional para-oriented aromatic polyamides as described above, it has been difficult to create a material that has both such low hygroscopicity and high elastic modulus.

[Invention tries to solve it! In view of the above problems, it is an object of the present invention to provide a para-oriented aromatic polyamide material that simultaneously satisfies high elastic modulus and low hygroscopicity when formed into fibers, films, etc.

[Means to solve the problem]

That is, the present invention has the following repeating unit: - Ship type; -NH-Ar + -NH-CO-Art-CO--, and in the formula, Ar+ and Arz each independently represent the following (1) or The divalent aromatic cyclic group in (2), and among all the aromatic cyclic groups, (1)
The pyrazine ring-containing aromatic polyamide is in the range of 0.1≦χ≦1 and has an intrinsic viscosity of at least 2.0 or more, where χ is the molar fraction of .

(Here, R,, R1, R3, and R4 can be the same or different and represent hydrogen or a monovalent substituent.

■Also, para-oriented aromatic dicarboxylic acid halide is expressed by the following formula (
3) and (or) (4), and the para-oriented aromatic diamines are the following formulas (5) and (6), and the para-oriented aromatic diamines are the following formulas (3) and (3).
) and (substantially equimolar amounts of para-oriented aromatic dicarboxylic acid halide and para-oriented aromatic diamine in which the sum of the molar fractions of (5) is 0.1 or more and 1.0 or less are reacted in an amide solvent. This is a method for producing a pyrazine ring-containing aromatic polyamide, which is characterized by the following.

(Here, R8 to R, can be the same or different and represent hydrogen or a monovalent substituent, and X is CI, Br,
The molar fraction of the pyrazine ring component in the pyrazine ring-containing aromatic polyamide of the present invention (representing a halogen atom) is 0°1 or more and 1.0
It is as follows. If this molar fraction is less than 0.1%, the expected degree of high elastic modulus and low moisture absorption rate will be very small, and only a polymer with a low degree of polymerization will be obtained. The sum of the molar fractions of the seven polymers (3) and (5) used is 0.1 or more.

Must be less than or equal to O.

In the pyrazine ring-containing aromatic polyamide of the present invention, none of the aromatic rings thereof may be substituted, or some or all of them may be WI'A-substituted with a monovalent substituent. The type of substituent is not particularly limited, but substituents that do not significantly reduce the reactivity of the monomer and are unlikely to cause side reactions are preferred, and generally include lower alkyl groups such as methyl and ethyl groups, halogen groups such as chloro, and methoxy groups. used in

The pyrazine ring-containing aromatic polyamide of the present invention may contain a small amount of units different from the above-mentioned repeating units, such as aliphatic, aromatic, or alicyclic units, to the extent that the function of the polyamide itself is not impaired. It can also contain repeating units.

As a monomer for producing the polymer, terephthalic acid siparide (one in which the halogen is chlorine is hereinafter referred to as TP)
L2.5-di(P-heroformylphenyl) designated as C
Pyrazine (hereinafter referred to as PCP when the halogen is chlorine), paraphenylenediamine (hereinafter referred to as PICA)
, 2,5-di(P-aminophenyl)pyrazine (hereinafter referred to as APP), and aromatic ring substituted products of these compounds are used.

The degree of polymerization of the pyrazine ring-containing aromatic polyamide in the present invention requires an intrinsic viscosity of at least 2.0,
Preferably it is 3.0 or more. If the intrinsic viscosity is less than 2.0, it is difficult to mold into fibers, films, etc., and it is impossible to obtain a molded product with the desired mechanical strength.

In the method for producing a pyrazine ring-containing aromatic polyamide of the present invention, para-oriented aromatic dicarboxylic acid halides represented by formulas (3) and (4), and para-oriented aromatic dicarboxylic acid halides represented by (5) and formula (6) are used. Polymerization methods used in the production of ordinary aromatic polyamides using oriented aromatic diamines, such as solution polymerization, interfacial polymerization, melt polymerization, etc., can be applied, and solution polymerization is particularly preferred. The sum of the molar fractions of formulas (3) and (5) containing pyrazine rings is 0.1 or more.1.
It is necessary that the amount is 0 or less, thereby making it possible to obtain the above-mentioned pyrazine ring-containing aromatic polyamide.

Furthermore, regardless of the molar fraction of the pyrazine ring-containing monomer, the para-oriented aromatic dicarboxylic acid halide and the para-oriented aromatic diamine must be in substantially equimolar proportions, specifically, one monomer component and the other The molar ratio with the monomer must be 9.95 or more and 1.05 or less,
Preferably it is 1. Exceeding this range, if either monomer component is present in excess, the degree of polymerization will be significantly reduced.

When producing the pyrazine ring-containing aromatic polyamide of the present invention by a solution polymerization method, the solvent used in the present invention is:
An amide solvent is used because it needs to have good solubility for the polymer used and the polymer obtained by the polymerization reaction.

In addition, it is preferable to use a substance that does not cause side reactions. Specifically, N-methyl-2-pyrrolidone (hereinafter referred to as NMP), hexamethylphosphortriamide (hereinafter referred to as IMP) is preferable.
Aprotic amide polar solvents such as ^) are preferably used. Furthermore, two or more of these solvents can be used as a mixture, but in either case, the concentration of impurities is preferably 0.1% by weight or less, more preferably 0.01% by weight or less. .

If the amount of impurities in the solvent increases, it becomes a cause of hindering the polymerization reaction, making it difficult to obtain a polymer with a high degree of polymerization.

Also, the lower the water content in the solvent, the better (preferably 110
It is 0 pp or less. This is the same as mentioned above (because it causes interference with the polymerization reaction).

In liquid polymerization, it is preferable to add a solubilizing agent to the polymerization reaction solution before or during the polymerization to increase the solubility of the solvent.

For example, calcium chloride, lithium chloride, lithium carbonate,
Calcium carbonate, calcium hydroxide, lithium hydroxide,
Examples include alkaline metal compounds such as lithium hydride and calcium hydride, with calcium chloride and lithium chloride being particularly preferred.

There is no particular problem with the purity of these solubilizing aids as long as they do not significantly inhibit the polymerization reaction, but in general, purity of 99.0% or more is preferably used. More preferably, it is 99.5% or more. If this purity is extremely low, it will be difficult to obtain a polymer with a high degree of polymerization because the solubility of the solvent will be insufficient or impurities will interfere with the polymerization reaction.

Further, from the viewpoint of shortening the dissolution time, the particle size is preferably such that it can pass through a 5-mesh sieve.

In order to produce a pyrazine ring-containing aromatic polyamide by the solution polymerization method of the present invention, a solution of a solubilizing agent, especially calcium chloride or lithium chloride, which satisfies the above conditions, is dissolved in a V solvent which also satisfies the conditions. to make. The amount added is 0.8 times or more 1.5 times the 7-mer concentration (MC).
It is preferably 1.3 times or more and 2.0 times or less, particularly preferably 1.3 times or more and 2.0 times or less.

If the amount added is less than this range, the resulting polymer may not be sufficiently polymerized or the polymer may precipitate early during the polymerization reaction. Further, even if the amount added exceeds this range, similar precipitation of the polymer will occur.

In the polymerization reaction of the present invention, the mixing of the 1,000-glycerides is preferably carried out as follows. That is, a solution is prepared by dissolving a solubilizing agent, such as calcium chloride or lithium chloride, in a solvent, and a para-oriented aromatic diamine is further added thereto, and the solution is adjusted to the polymerization initiation temperature described in 4. , para-oriented aromatic dicarboxylic acid halide may be added to advance the solution polymerization reaction.

The monomer concentration (MC) in the present invention is 0°5 mol
#! The following is preferable: If it exceeds 0.5 mol/1, the polymer will precipitate extremely quickly after the start of the polymerization reaction, making it difficult to obtain a polymer with a high degree of polymerization.

Moreover, in order to obtain a polymer with a high degree of polymerization, the polymerization initiation temperature (T) is preferably set to -10°C to 10°C. If T is less than 10°C, the polymerization reaction of the resulting polymer will not proceed sufficiently, and if T exceeds 10°C, polymer precipitation will occur during the polymerization reaction, and even if the temperature is low, polymers with a high degree of polymerization may not be produced. difficult to obtain. Polymerization initiation temperature (
The temperature of the cooling bath for adjusting T) is -50°
Examples of the refrigerant selected from C to 0'C include brine, methanol, ethanol, ice water and calcium chloride, but any refrigerant may be used as long as it satisfies the above temperature.

The temperature after the start of the reaction is preferably selected to be 10 to 100°C, more preferably 30 to 80'C.

If the temperature after the start of the reaction exceeds 80"C, decomposition of the polymer may occur in the polymerization reaction pile, and this is not suitable for obtaining a polymer with a high degree of polymerization.

After the polymerization starts, the polymerization reaction system gradually increases in viscosity, changes from a paste-like state to a gel-like state, and becomes powder-like or granular-like by further kneading. As a polymerization reaction apparatus that can add sufficient stirring and mixing to such a polymerization reaction system, for example, a single-screw or twin-screw extruder,
Examples include a continuous Niegoo mixer, a reciprocating rotary reactor, and a vertical stirring tank. In the laboratory, a small test kneader or a small vertical stirring tank is conveniently used. In such an apparatus, a polymer having a high degree of polymerization can be obtained by kneading the polymerization reaction until it becomes powder or granules.

Various additives such as antioxidants and ultraviolet absorbers can be added during the polymerization reaction to the extent that they do not interfere with the reaction.

After the completion of the polymerization reaction, the powdered or granular polymerization reaction product is washed as it is with water, aqueous alkaline solution, acetone, methanol, chloroform, etc., and then dried and isolated as a polymer.

The pyrazine ring-containing aromatic polyamide of the present invention can be molded into fibers, films, fibrids, etc. from a dope prepared by redissolving it in a solvent such as sulfuric acid using a wet molding method or a so-called dry jet wet molding method. Can be done.

These molded bodies have high strength and heat resistance1 similar to PPTA.
．． In addition to chemical resistance, it also has excellent elastic modulus and low moisture absorption.

In addition, it can be processed chemically and mechanically in the same way as PPTA molded products, and is expected to be widely used as industrial materials, clothing fibers, and high-performance films.

(Example) Examples of the present invention are shown below, but these are not constituted as limiting the present invention.

Intrinsic viscosity (η1n
h) is i! of 98.5 times i1χ! Concentration C=0.2 in sulfuric acid
A solution containing a polymer dissolved in g/d2 was measured at 35°C using a conventional method.

Intrinsic viscosity (η1nh) = in ηrel/C Examples 1 to 3 and Comparative Examples 1 to 3 35 d of NMP purified by distillation was charged into a dried glass flask with an internal volume of about 100, and further 2.331 g was charged.
(21n+ mol) of CaCl, and 1.514g (
14 mmol) of PDA was charged and dissolved at room temperature. Next, the solution temperature in the flask was prepared with dry ice-methanol at 20°C so that the temperature was as shown in Table 1, and then PCP and TPC powders were added in the amount shown in Table 1. Stir vigorously. PCP and TPC were quickly dissolved, and the polymerization reaction system gradually increased in viscosity and became gel-like, but it was continued to be vigorously stirred and kneaded until the polymerization reaction product became powder-like. The powdered polymerization reaction product was taken out, washed with water, dried to isolate the polymer, and the intrinsic viscosity (η1n
h) was measured. The results are shown in Table 1.

Example 4 CaC] 0.597 g (14 m mol) instead of z
Polymerization was carried out in the same manner as in Example 1 except that LiC1 was used. The results are shown in Table 1.

Example 5 3.668g (14w mol) of PDA instead
Polymerization was carried out in the same manner as in Comparative Example 2 except that pp was used. The results are shown in Table 1.

(Spinning Example) The polyamide synthesized by the method shown in Example 1 and Comparative Example 2 was dissolved in 'a sulfuric acid of 99.9χ so that the polymer concentration was 13χ while maintaining the temperature at 80°C, and spinning was carried out. A polymer solution was prepared. It was confirmed by polarizing microscope observation under crossed Nicols that this polymer solution exhibited optical anisotropy.

This polymer solution was used for spinning after degassing under vacuum for 2 hours. Polymer solution was added using a microfeeder for 20 to 4
0.1 m+1 at extrusion speed of 0 ttdl/hr
The mixture was extruded through a nozzle with a hole diameter of φ into the coagulation bath through 2 mm of air. The coagulation bath is water cooled to 0-1''C. The filament extruded into the coagulation bath is taken up with a Nelson roll, and then wound onto a bobbin with a wine goo.

The filament thus wound onto the bobbin was then washed by immersing the whole bobbin in running water, and then dried in a hot air dryer at 100° C. for 2 hours.

Table 2 shows the tensile properties and moisture absorption rate of the obtained fibers.

〔Effect of the invention〕

The pyrazine ring-containing aromatic polyamide of the present invention is a para-oriented aromatic polyamide that has both low hygroscopicity and high elastic modulus due to its structural characteristics. In addition to similar high strength, heat resistance, and chemical resistance, it also has superior elastic modulus and low moisture absorption, and is expected to be widely used as industrial materials, clothing fibers, and high-performance films.

Claims (2)

[Claims] (1), has a general formula; -NH-Ar_1-NH-CO-Ar_2-CO-, and in the formula, Ar_1 and Ar_2 each independently represent the following divalent (1) or (2). aromatic cyclic group, and among all the aromatic cyclic groups, (1
) A pyrazine ring-containing aromatic polyamide having an intrinsic viscosity of at least 2.0, which is in the range of 0.1≦χ≦1, where χ is the molar fraction of ▲There are mathematical formulas, chemical formulas, tables, etc.▼…………(1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼…………(2) (Here, R_1, R_2, R_3, R_4 are the same or different. , and represents hydrogen or a monovalent substituent. (2), the para-oriented aromatic dicarboxylic acid halide has the following formula (
3) and (or) (4), and the para-oriented aromatic diamine is the following formula (5) and (or) (6), and the sum of the molar fractions of the following formulas (3) and (5) is 0. .1 or more and 1.0 or less, substantially equimolar amounts of para-oriented aromatic dicarboxylic acid halide and para-oriented aromatic diamine are subjected to a solution polymerization reaction in an amide solvent. A method for producing aromatic polyamide. ▲There are mathematical formulas, chemical formulas, tables, etc.▼…………(3) ▲There are mathematical formulas, chemical formulas, tables, etc.▼…………(4) ▲There are mathematical formulas, chemical formulas, tables, etc.▼…………(5 ) ▲There are mathematical formulas, chemical formulas, tables, etc.▼…………(6) (Here, R_1 to R_8 can be the same or different and represent hydrogen or a monovalent substituent, and X is Cl, Br
, represents a halogen atom of I. )