Patent GB-1068285-A (GB)
Title: Polyamides,polybenzoxazinones,and the preparation thereof
IPC: C08G73/06
Filed: 1965-06-16
Abstract: Linear polyamides having the formula <FORM:1068285/C3/1> wherein (Ar) is a tetravalent aromatic radical having at least 6 carbon atoms, R is a divalent radical, R1 is a monovalent radical selected from hydrogen, alkyl radicals of 1 to 6 carbon atoms and a phenyl radical, the bonds (1) and (2), similarly as with bonds (3) and (4), being directly bonded to carbon atoms adjoining each other on the aromatic radical, and n is an integer sufficiently large that the inherent viscosity measured in a 0.5% solution of the polymer in concentrated sulphuric acid at 30 DEG  C. becomes at least 0.1 are prepared by reacting at a temperature not exceeding 200 DEG  C. (a) at least one aromatic diamino dicarboxylic acid having the formula <FORM:1068285/C3/2> with (b) at least one dicarboxylic acid component having the formula X-R-X, wherein X is a monovalent functional radical which is capable of forming a carboamide by reacting with the amino radical of the aromatic diamino dicarboxylic acid component. Oxazinone ring containing polymers of the formula <FORM:1068285/C3/3> may then be prepared from the linear polyamides by effecting an intramolecular cyclization with elimination of R1OH from the linear polyamides.  Suitable aromatic diamino dicarboxylic acid components which may be used include amongst many others, 3,31-benzidine dicarboxylic acid and the methyl and ethyl esters thereof, 2,5-diamino terephthalic acid, 4,6-diamino isophthalic acid, diphenyl 2,7-diamino - 3,6 - naphthalene dicarboxylate, bis (3 - amino - 4 - carboxyphenyl) ether and 2,2 - bis (3 - amino - 4 - carboxyphenyl) propane. The amine salts of such compounds with hydrochloric acid may also be used.  The monovalent functional radical X of the dicarboxylic acid component (b) is preferably a <FORM:1068285/C3/4> radical, where R1 is as above and Hal is a halogen atom. Included amongst suitable components (b) are terephthalic acid, ethyl terephthalate, terephthalamide isophthaloyl chloride, 1,5 - naphthalene dicarboxylic acid, 4,41-biphenyl carboxylic acid, 4,41-diphenyl methane dicarboxylic acid, bis (4-chlorocarboxylphenyl) methane, 2,2 - bis (- 4 - carbamoylphenyl) propane, bis (4 - chlorocarboxyphenyl) ether, oxalic acid, adipic acid, adipic acid chloride, adipamide and ethyl adipate.  Generally the reaction is carried out in an inert organic solvent such as those of the N,N-dialkyl carboxylic amide group and the system may have an alkali metal salt or alkaline earth metal salt dissolved therein. Alternatively polyphosphoric acid may be used as the liquid medium for the reaction.  The cyclizing reaction to form the polybenzoxazinones may be carried out either by heating the polyamides to at least 200 DEG  C. or in the case where R1 is hydrogen by treating the polyamides with a dehydrating agent.  In the case of the former method it is preferred to heat the polyamides under a reduced pressure of below 10 mm. Hg or in a non-oxidizing atmosphere such as nitrogen, argon or CO2.  Preferred dehydrating agents are anhydrous basic organic solutions containing a carboxylic acid anhydride, amines or metal alkoxides being the most suitable basic compounds.