JPS59199717A - Preparation of polyamide - Google Patents

Abstract

PURPOSE:To obtain polyamide useful as a material in the field of electricity and machinery requiring strength and heat resistance, simply and efficiently, by subjecting directly a dicarboxylic acid as it is and a diamine to polycondensation in the presence of diphosphorus pentoxide without passing the dicarboxylic acid through chlorination process. CONSTITUTION:A dicarboxylic acid (e.g., isophthyalic acid, etc.), a diamine[preferably aromatic diamine such as bis(4-aminophenyl)ether, etc.] and diphosphorus pentoxide (preferably 1-2mol diphosphorus pentoxide based on 1mol dicarboxylic acid) are added to a reaction system, and, if necessary, an alkaline(earth) metal halide (e.g., lighium chloride, etc., preferably 0.5-1.5mol alkaline metal halide based on 1mol dicarboxylic acid) is added to it, and polycondensation is carried out preferably at 60-100 deg.C, to give the desired polyamide.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polyamide, and more particularly to a method for efficiently producing a high molecular weight polyamide by directly reacting a dicarboxylic acid and a diamine in the presence of diline pentoxide.

In general, polyamides, especially polyamides containing aromatic rings, have excellent heat resistance and are therefore widely used in various fields. Such polyamides have conventionally been produced by polycondensing dicarboxylic acid chloride and diamine in the presence of an alkali. However, in the above conventional method, dicarboxylic acid is used as a chloride, so this chloride must be isolated. However, it is difficult to isolate and store because it is easily hydrolyzed.

An object of the present invention is to develop a method for efficiently producing polyamide through a simple process of directly reacting dicarboxylic acid with diamine without going through a dicarboxylic acid salting step.

The present inventor has conducted extensive research in order to achieve this objective.

As a result, they discovered that the objective could be achieved by allowing niline pentoxide to exist in the reaction system, and completed the present invention. That is, the present invention provides a method for producing a polyamide, which is characterized by subjecting a dicarboxylic acid and a diamine to a polycondensation reaction in the presence of diline pentoxide.

The dicarboxylic acid that can be used in the method of the present invention is not particularly limited, and various types can be used.

Specifically, adipic acid, pimelic acid, speric acid, azelaic acid, and sebacic acid.

Examples include phthalic acid, isophthalic acid, and terephthalic acid.

On the other hand, various diamines can be used, including alkylene diamines such as ethylene diamine, trimethylene diamine, and tetramethylene diamine, and various aromatic diamines. Especially one of them
Considering the heat resistance of the polyamide product, monoaromatic diamines are preferred, and specific examples include compounds represented by the following formulas.

It is necessary to react in the presence of niline pentoxide. If niline pentoxide is not present in the reaction system, the polycondensation reaction between dicarboxylic acid and diamine will hardly proceed. The amount of diline pentoxide used here may be determined as appropriate depending on various conditions, but generally it is 0.
The amount may be 5 to 3.0 times by mole, preferably 1.0 to 2.0 times by mole.

In the method of the present invention, it is also effective to add an alkali metal halide or alkaline earth metal halide to the reaction system, if necessary.

These alkali metal halides and alkaline earth metal halides serve to increase the solubility of the raw material compounds and initial reaction products in the reaction system, thereby increasing the reaction rate and the molecular weight of the resulting polyamide. It will be done.

Here, examples of the alkali metal halides include lithium chloride and potassium chloride, and examples of the alkaline earth metal halides include calcium cyclide and magnesium chloride. The amount of these alkali metal halides or alkaline earth metal halides to be added may be determined as appropriate, but is usually 0 to 2.0 times the mole of dicarboxylic acid, which is one of the raw material compounds, preferably 0. The amount may be .5 to 1.5 times the mole.

In carrying out the method of the present invention, the above-mentioned dicarboxylic acid, diamine and diline pentoxide are added to the reaction system,
Further, if necessary, an alkali metal halide or an alkaline earth metal halide is added and heated to a predetermined temperature, usually Fi.
The reaction may be carried out at 20-130°C, preferably 60-100°C. This reaction, that is, the polycondensation reaction between dicarboxylic acid and diamine, may be carried out without a solvent.
Usually N-methyl-2-pyrrolidone, hexamethylphosphoramide 1. Proceed in a solvent such as pyridine.

According to the method of the present invention, it is possible to efficiently obtain polyamide from very inexpensive raw material compounds through an extremely simplified production process, and furthermore, this polyamide has a polymerization degree of 5.
0-200. It has a relatively large molecular weight with an intrinsic viscosity of about 0.15 to 0.85 di/y.

Therefore, the polyamide produced by the method of the present invention can be used in electrical appliances that require strength and heat resistance.

Effectively used as a variety of materials in the mechanical field.

Next, examples of the present invention will be shown.

Example 1 20m/! Dis 1pentoxide 71.23 in an Erlenmeyer flask
56 F (8.71 mmol) and 5 ml of N-methyl-2-pyrrolidone were added and stirred to dissolve.

Next, 0.4820 t (2.g mmol) of isophthalic acid was added and reacted at 80°C for 1 hour, and then 0.245f (5.8 mmol) of lithium chloride was added and reacted at 80°C for 1 hour.
Allowed time to react. Next, bis(4-aminophe-1:
/I/ )! -TE# 0.5803 f (2.9 mmol) was added and a polycondensation reaction was carried out at 80°C for 24 hours. Thereafter, the reaction product was placed in a 1% aqueous solution of NaHOO3 at 500 mA', filtered, washed with water, and dried under reduced pressure to obtain a polyamide. The polymer yield in this case is 99
%, and its intrinsic viscosity (0.5 g/dl in concentrated sulfuric acid)
l, measured at 30°C. same as below. ) is 0°28a
It was J/r.

Example 2 A polyamide was obtained in the same manner as in Example 1, except that 2-9 mmol of adipic acid was used instead of isophthalic acid. The polymer yield in this case is 97
%, and its intrinsic viscosity was 0.85 d1/2.

Example 3 A polyamide was obtained in the same manner as in Example 1 except that 2.9 mmol of sebacic acid was used instead of isophthalic acid. The polymer yield in this case is 9
6%, and its intrinsic viscosity is 0.45d1. /l.

Example 4 Same as Example 1 except that 2.9 mmol of adipic acid was used instead of isophthalic acid and 2.9 mmol of bis(4-aminophenyl)methane was used instead of bis(4-aminophenyl) ether. A polyamide was obtained in the same manner as in Example 1. The polymer yield in this case is 98%,
Its intrinsic viscosity is 0.33 di/? Met.

Example 5 In Example 1, 2.9 mmol of sepa7ic acid was used instead of isophthalic acid, and 2.9 mmol of bis(4-aminophenyl) sulfone was used instead of bis(4-aminophenyl) ether.
A polyamide was obtained in the same manner as in Example 1 except that IJmol was used. The polymer yield in this case was 99% and its intrinsic viscosity was 0.31 dl-/l.

Example 6 In Example 1, 2.9 mmol of adipic acid was substituted for isophthalic acid, and 2.9 mmol of bis(4-aminophenyl) sulfide was substituted for bis(4-aminophenyl) ether.
A polyamide was obtained in the same manner as in Example 1 except that 9 mmol was used. The polymer yield in this case was 99% and its intrinsic viscosity was 0.24 d, Jl-/f.

Patent applicant: Idemitsu Kosan Co., Ltd.

Claims (2)

[Claims] (1) A method for producing polyamide, which comprises subjecting a dicarboxylic acid and a diamine to a polycondensation reaction in the presence of diline pentoxide. (2) The method according to claim 1, in which a. silica metal chloride or alkaline earth metal chloride is added to the reaction system.