GB747614A - Improvements in the viscosity stabilisation of polyamides - Google Patents

Abstract

Polyamides are viscosity stabilized with o-phenylene diamine or a C or N substitution derivative thereof, the substituent group not being reactive with an amino or carboxy group. Only one hydrogen on one amino group may be substituted. The o-aromatic diamine may be included in the reaction mixture or may be reacted with the formed polyamide and is used in a quantity up to 4 mol. per cent of the dicarboxylic acid (in a dicarboxylic acid-diamine reaction) or of the amino-acid (in an amino-acid condensation). Twenty-nine suitable substitution derivatives are specified. In examples (1) 225 parts hexamethylene diammonium adipate, 150 parts water and 1.02 part o-phenylene diamine are heated at 290 DEG C. in an autoclave for 3 1/2 hours, the pressure then being released slowly. The relative viscosity, dye uptake and carboxy and amino end group content are compared with those from a polyamide viscosity stabilized with acetic acid. Example (2) is similar but using different polymerization conditions. (3) A short chain polymer is made from hexamethylene diammonium adipate by heating at 220 DEG C. for 3 hours. To 10 parts of the polymer 0.046 parts o-phenylene diamine are added and the mixture heated at 285 DEG C. for 30 minutes. The relative viscosity and amino end group content of the polymer are compared with those of an acetic acid stabilized polymer. Example (4) demonstrates the stabilizing effect of o-phenylene diamine when the polymer is heated at 285 DEG C. for 1 hour. In further examples 1 - methyl - 3 : 4 - diaminobenzene, 1 : 2 - dimethyl - 3 : 4 - diaminobenzene, 1 : 2-diaminonaphthalene, 1 - chloro - 3 : 4 - diamino benzene and N-methyl-o-phenylene diamine are used instead of o-phenylene diamine. Specifications 461,236, 461,237, 495,790, 533,306 and 533,307 are referred to.