CS260187B1 - Process for producing polyaramides - Google Patents

Abstract

A method for producing highly thermostable polyaramids with low solubility even in polar solvents by mutual reaction of compounds of the general formula I with compounds of the general formula ROOC—Arz—COOR in the presence of polar solvents and in an inert atmosphere. The production can also be carried out in the melt so that the mixture of selected reactants in the form of a melt is continuously introduced into the editorial zone, through which it passes for a certain time. In the above formulas, An and Arz optionally denote methyl or chlorine-substituted phenylene, Rl and R2 hydrogen, methyl, chlorine, methoxy or ethoxy and R methyl or ethyl. The reaction is carried out at a temperature of 180 to 380 °C for 1 to 8 hours.

Description

This invention relates to the polyaramid and its essence is the reaction between N, N'-bis (aminophenyl) -benzendlkarboxamidy, optionally substituted on the aromatic nuclei, and esters of benzenedicarboxylic acids, optionally substituted, at temperatures of 180-380 DEG C. ^b

Until now, polyaramides of the Kevlar and Nomex type have been produced by polycondensation of phenylenediamines or their salts with terephthalic or isophthalic chlorides (Du Pont, Belgium patents 565 266, 565 267, 565 268). The actual polycondensation is generally carried out in an environment of active organic solvents and the product obtained is finally freed from both co-solvents and hydrogen chloride formed in the reaction. Removing acidity is a lengthy and technically demanding process.

According to the present invention, polyaramides are prepared by interacting with compounds of formula I

wherein An represents a benzene radical, optionally substituted by CH3 or Cl, R1 and R2 denote H, CH3, Cl, OCH3 or OC2H5, wherein R1 and R2 may be the same or different and the compounds of the general formula

ROOC — Al'2 — COOR, where Ar2 has the same meaning as An, wherein An and Arz may be the same or different, R = CH3 or C2H5, at temperatures of 180 to 380 ^° C for 1 to 8 h, optionally in the presence of polar solvents, preferably under an inert atmosphere.

'The invention is based on the recognition that comparatively complicated diamines of general formula I possess an unexpected thermal stability so that it can carry out the reaction with di-N2- ROOC-COOR ¹ in the melt at temperatures unusual in organic synthesis. Optional addition of polar solvents such as 1-methylpyrrolidone, Ν, Ν-dimethylaeetamide, N, N-dimethylformamide, Ν, Ν-diethylformamide, dimethylsulfoxide, pyridine, phosphoric esters or alkylated phosphoric amines and the like (one or a mixture of solvents may be used) ), facilitates the stirrability of the reactive system and may affect the degree of polycondensation.

Groupings are formed during the reaction

wherein Ar 1, Ar 2, R 1, R 2 are as defined above, wherein the terminal groups may be two amino groups or two —COOR or one — NH2 and one — --COOR.

The desired diamino compounds of formula I can be prepared, for example, by reduction of the corresponding dinitroderivatives obtained by the methods of OA 193 137 and AO 198 794 or by the controlled reaction of terephthalic acid dichloride and p-phenylenediamine (Japanese patent Asahi Chem. Co. Ltd., Jpn. Kokai Tokkyo). Koho 79 28, 395; CA 91, 21423 (1979). Benzene dicarboxylic acid diesters are readily available, e.g., by esterification of the free acids. Some of the diesters - eg dimethyl terephthalate - are prepared in considerable tonnages in the production of PES fibers.

In carrying out the actual condensations of the present invention, the selected reactants are heated to temperatures of 180 to 380 ° C, first melting and then condensing. The degree of reaction taking place is, on the one hand, the amount of alcohol liberated - for example, methyl alcohol using dimethyl ter- or dimethylisophthalate - and, on the other hand, the continuous increase in the viscosity of the reaction mixture. The function of the polar solvents, if any, has already been defined. The optimal ratio of the starting diamines I and diesters of dicarboxylic acids expressed in molar ratio is 1: 1; a slight excess of some of the components may not significantly affect the course of the reaction. The polycondensation proceeds even with a considerable excess of some component, but usually a suitable mol is not achieved. weight. Heating of the system to the reaction temperature can be carried out either gradually and then gradually increased up to 380 ° C, or the system is quickly heated to the selected reaction temperature in the interval 180 to 380 ° C and maintained at this temperature for 1 to 8 hours. Alternatively, the mixture of components is continuously fed into a continuous reactor with a reaction zone at a temperature between 180 ° C and 380 ° C, through which the mass passes through a specified time schedule. During polycondensation, volatile alcohol escapes from the system and its excess pressure in the reactor can be reduced by vapor discharge.

The resulting polyaramides are highly thermostable and are characterized by a relatively low solubility in the polar solvents listed above.

Example 1

1 mole of N, N'-bis (4-amnophenyl) -1,4-benzenedicarboxamide and 1 mole of dimethyl terephthalate are poured into the autoclave, the autoclave is sealed, flushed with nitrogen and the mixture is heated to 300 ° C over 1.5 h. and held at this temperature for 4 h; the reaction overpressure is maintained at 0.8 MPa by occasional evaporation of the methanol vapors. 480 g of a yellowish polycondensate are obtained. In place of 1 mole of N, N'-bis (4-aminophenyl) -1,4-benzene dicarboxamide, 1 mole of N, Nibis (4-aminophenyl) -1,3-benzene dicarboxamide can be used and then a polycondensate with m-configuration in the molecule is obtained. ; can also be used

N, N‘-bis- (3-aminophenyl) -1,3-benzenedicarboxamide.

Example 2

1 mol of N, N'-bis (4-amino-2,5-dimethylphenyl) -1,4-benzenedicarboxamide, 1 mol of dimethyl terephthalate and 500 ml of 1-methylpyrrolidone are mixed in the autoclave, the autoclave is closed, flushed with nitrogen and the mixture is The mixture is heated to 180 DEG C. over a period of 1.5 hours and then the temperature is gradually raised to 350 DEG C. over a period of 5 hours while maintaining a positive pressure of about 1.0 MPa. After cooling, 542 g of almost dry polycondensate are obtained.

Instead of N, N'-bis (4-amino-2,5-dimethylphenyl) -1,4-benzenedicarboxamide, 1 mole of N, N'-bis (4-amino-2-methyl-5-chloro- phenyl) -1,4- or -1,3-benzenedicarboxamide and 1 mole of dimethyl isophthalate in place of dimethyl terephthalate.

Example 3

A mixture of 1 mol of N, N'-bis (4-aminophenyl) -1,4-benzenedicarboxamide, 1.1 mol of dimethyl terephthalate and 400 millimeters of Ν, dim-dimethylacetamide is heated to 180 ^° C in a stirred reactor, and the mixture is then brought to of a flow reactor having a reaction zone of 340 ° C and passing therethrough is condensed analogously to AO 199 162. A polycondensate of similar quality as in Example I is obtained.

Claims (2)

I will invent the object A process for the production of polyamides, characterized in that they interact with compounds of the general formula I Rf N - NH0C 'Atij-CONH' · Oj ' ¹ R ~ ⁿ _/} wherein Ar represents benzenický radical, optionally substituted with CH 3 or Cl, R, and R2 represents H, CH3, Cl, OCH3 or OC2H5, wherein Ri and R2 may be the same or different, and a compound of the formula ROOC-Ar 2 —COOR, wherein Ar2 has the same meaning as Ar1, wherein Ar1 and Ar2 may be the same or different, R = CH3 or C2H5, at temperatures of 180 to 380 ° C for 1 to 8 h, optionally in the presence of polar solvents, preferably in inert atmosphere. 2. A process according to claim 1, characterized in that the mixture of selected reactants, preferably in the form of a melt, is continuously introduced into the reaction zone at a temperature of 180 to 380 [deg.] C. and passes through the zone during 1 to 8 hours.