JPS5910372B2 - Houkozoku polyamide no seizou hohou - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for producing aromatic polyamide.

More specifically, the present invention relates to an improved method for producing an aromatic polyamide by thermally condensing an aromatic dicarboxylic acid and an aromatic diamine. Aromatic polyamides, such as poly p-
Polyamides such as phenylene terephthalamide and polym-phenylene isophthalamide have excellent properties such as high thermal stability, high rigidity, and high tensile strength. researched.

The manufacturing method involves reacting an aromatic diamine and an aromatic dicarboxylic acid chloride in the presence of a dehydrochlorination agent.

2) Heat condensation of aromatic diamine and aromatic dicarboxylic acid ester.

3) Direct heating condensation of aromatic diamine and aromatic dicarboxylic acid.

etc.

Among these, if a high polymer can be obtained by the direct polymerization method 3), aromatic polyamides can be obtained industrially very advantageously. Conventionally, regarding this direct polymerization method, a method has been proposed in which terephthalic acid and paraphenylenediamine are thermally condensed in a solvent such as diphenylsulfone using balatoluenesulfonic acid as a catalyst.

However, although a relatively high polymer can be obtained by this method, the degree of polymerization of the obtained polymer is not sufficiently high and is highly colored, which is not preferable. The present inventors have conducted extensive research into methods for producing aromatic polyamides that do not have these drawbacks, and as a result, have arrived at the method of the present invention.

That is, in the present invention, when producing an aromatic polyamide by condensing at least one aromatic dicarboxylic acid and at least one aromatic diamine in a liquid phase at a high temperature of 200° C. or higher, the condensation reaction is carried out mainly using diarylsulfone. This is a method for producing an aromatic polyamide, characterized in that the method is carried out in a solvent in the presence of a catalyst selected from the group consisting of phosphoric acid, phosphoric acid esters, and partial alkali metal salts thereof.

In the method of the present invention, any aromatic dicarboxylic acid that is conventionally known as a raw material for this type of aromatic polyamide can be used.

Specific examples of such aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, and diphenyl ether.
, 4'-dicarboxylic acid, diphenylsulfone 4, 4
'-dicarboxylic acid, diphenoxyethane-4,4'
-dicarboxylic acid, - Diphenylketone-4,4'-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, etc. can be exemplified. Particularly preferred among these are terephthalic acid and isophthalic acid; when these aromatic dicarboxylic acids are used, the polycondensation rate is fast and industrially useful aromatic polyamides can be easily produced. Further, as the aromatic diamine, an aromatic diamine conventionally used in the production of this type of aromatic polyamide can be used. Such aromatic diamines include, for example, p-phenylene diamine, m-phenylene diamine, diphenyl ether-4,4'-diamine, diphenyl ether-3,4'-diamine, 4,4
'-diaminobiphenyl and the like can be mentioned. Among these, p-phenylene diamine, m-phenylene diamine, diphenyl ether-4,4'-diamine, diphenyl ether-3,4'-diamine and the like are particularly preferred. The ratio of the aromatic diamine to be used is 0.8 to 1.5 moles, preferably 1 to 1.5 moles, relative to the aromatic dicarboxylic acid.
The amount is preferably 2 times by mole, particularly preferably 1 to 1.1 times by mole.

In the method of the present invention, the aromatic polyamide is produced by subjecting the aromatic dicarboxylic acid and aromatic diamine to a heating reaction at a high temperature of 2000 C or more in the presence of a solvent and a catalyst having a melting point below the condensation temperature.

As the solvent, an organic solvent mainly composed of diarylsulfone such as diphenylsulfone and ditolylsulfone is used.

The amount of the solvent to be used is 0.1 to 100 times, preferably 0.5 to 50 times, particularly preferably 2 to 20 times the weight of the aromatic polyamide to be produced.

Moreover, when the above-mentioned solvent is not used, it is difficult to obtain an aromatic polyamide that is easily soluble in the polyamide solvent described below and has a high degree of polymerization.

The catalyst used in the present invention is selected from the group consisting of phosphoric acid, phosphoric esters and partial alkali metal salts thereof.

One or more types of these can be used. Here, phosphoric acid refers to orthophosphoric acid, phosphorous acid, hypophosphorous acid, birophosphoric acid,
It is an oxygen acid of phosphorus such as polyphosphoric acid, etc., and phosphoric acid ester is an ester of the above-mentioned phosphoric acid and alcohol or phenol, and their partial alkali metal salt is one per phosphorus atom contained in the molecule. or partial metal salts of the phosphoric acid and phosphoric acid ester containing alkali metal ions or less.

The alkali metals include lithium, sodium, potassium, cesium, rubidium, and the like. Specifically, the phosphoric acid esters include CH3OPO2H2, C2H, OPO2H2, C4H,
OPO2H2, C6H5OPO2H2, (CH3O)2
P0H1(C4H,O)2P0H,(C6H,O)2P
0H(CH3O)3P1(C4H,O)3P1(CH3
C6H4O)3P1(CH3O)(C4H,O)2P1
(C4H,O)(C6H5O)2P1(CH3O)(C
2H,OXC4H,O)PlCH,OPO(0H)2,
C3H7OPO(0H)2, (CH3O)2P0(0H
), (C2H5O)2P0(0H), (C,H,lO)
2P0(0X(C6H,O)2P0(0H),(CH3
O)3P0, (C2H5O)3P01(C4H,O)3
P01(C2H5O)2(C6H5O)POl(C2H
5O)(C3H7O)(C6H,O)POl(C2H5
O) POP(0C2H,)2, CH3OPO(0H)0
Examples include P0(0H)0CH3.

In addition, specific examples of partial alkali metal salts of phosphoric acid or phosphoric acid ester include NaIIPO4, KH2PO4, N
aH2PO2, NaOPO(0H)0P0(0H)0N
a1(CH3O)2P0(0Na), C3H7OPO(
0H) (0K), (CH3O)2P (0K), C2H5
OP (0H) (0Na), LiH2PO4, CSH2P
O4, RbH2PO4, (C6H5O)2P0(0Li
), C6H5OPO(0H)(0Na), and the like.

Among these compounds, preferred are pentavalent phosphorus compounds. The amount of the catalyst used is 30 mol % or less in terms of phosphorus atoms based on the aromatic dicarboxylic acid, preferably 10 to 0,001 mol %. , more preferably 5 to 0.00
5 mol%, particularly preferably 5 to 0.01 mol? It is.

If the amount of catalyst used is too large, not only will the resulting aromatic polyamide be markedly colored, probably due to thermal decomposition of the aromatic polyamide during the condensation reaction, but the rate of the condensation reaction will slow down. In the method of the present invention, the condensation reaction is carried out at a temperature of 200°C or higher, preferably 220-450°C, particularly preferably 240-380°C.

If the condensation reaction temperature is too low, the condensation reaction rate will be slow, and if it is too high, the resulting aromatic polyamide will be colored.
Undesirable. The condensation reaction time varies depending on the condensation reaction temperature, but is required to be at least 1 hour, preferably 3 to 3 hours.
30 hours, particularly preferably 5 to 10 hours. The aromatic polyamide obtained by the method of the present invention has better thermal stability and color tone than the conventional method. It also has the advantage that it can be molded industrially advantageously, depending on its solubility. The method of the present invention will be described below with reference to Examples.

Incidentally, the reduced specific viscosity (ηSp/c) shown in the examples was obtained by dissolving the aromatic polyamide in concentrated sulfuric acid, and the concentration (C) was 1.29/c.
dl at 35°C.

Moreover, "parts" means parts by weight. Example 1 8.3 parts of terephthalic acid, 5.4 parts of p-phenylenediamine
parts, 50 parts of diphenylsulfone and 0.1 part of orthophosphoric acid (
2.0 mol% based on terephthalic acid) was charged into a reactor, reacted for 20 minutes at 250°C in a nitrogen stream, and then
The temperature was raised to 360°C over a period of 15 minutes, and the condensation reaction was carried out at 360°C for 150 minutes while water produced as a result of the reaction was distilled out of the reaction system.

After the reaction was completed, the reaction mixture was cooled, then acetone was added thereto, and the mixture was taken out from the reactor and further evaporated.

Subsequently, the aromatic polyamide containing a small proportion of diphenyl sulfone was transferred again to the Soxhlet type 1 extractor and extracted with acetone. The yield of aromatic polyamide was 11.5 parts (yield 97%), and ηSp/c was 4.53.

Moreover, the sulfuric acid solution (concentration 19/1d1) of the aromatic polyamide obtained here was pale yellow in color. Comparative Example 1 0 p-toluenesulfonic acid instead of 0.1 part of orthophosphoric acid
．． An aromatic polyamide was condensed in exactly the same manner as in Example 1, except that 17 parts (2.0 mol % based on terephthalic acid) was used.

The yield of the aromatic polyamide obtained was 11.4 parts (yield: 9
6%), and ηSp/c was 1.42. Also,
A sulfuric acid solution of the aromatic polyamide obtained here (concentration 19
/1d1) was dark and colored. It can be seen that this aromatic polyamide is highly colored compared to the aromatic polyamide of Example 1. Examples 2 to 15 Aromatic polyamides were polymerized in the same manner as in Example 1, except that 1.0 mol% of various catalysts shown in Table 1 were used based on terephthalic acid instead of orthophosphoric acid (H3PO4). .

The results obtained are shown in Table 1. Example 16 An aromatic polyamide was polymerized in the same manner as in Example 6 except that 50 parts of ditolyl sulfone was used instead of diphenyl sulfone.

Claims (1)

[Claims] 1. When producing an aromatic polyamide by condensing at least one aromatic dicarboxylic acid and at least one aromatic diamine in a liquid phase at a high temperature of 200° C. or higher,
Production of an aromatic polyamide characterized in that the condensation reaction is carried out in a solvent mainly composed of diarylsulfone in the presence of a catalyst selected from the group consisting of phosphoric acid, phosphoric acid esters and partial alkali metal salts thereof. Method.