GB1202698A - Polyamides - Google Patents

Abstract

1,202,698. Polyamides. IMPERIAL CHEMICAL INDUSTRIES Ltd. 11 Oct., 1967 [28 Oct., 1966], No. 48485/66. Heading C3R. Synthetic linear polyamides are stabilized by a phenol substituted in the aromatic nucleus in one of the ortho positions to the phenolic OH group by an aliphatic, cycloaliphatic or araliphatic hydrocarbon radical in which the C atom joining the said radical to the phenolic nucleus is a saturated C atom attached to at least two other C atoms other than the C atom of the phenolic nucleus. The phenol also contains a carboxyl group (or carboxylic ester, carbamyl, N-substituted carbamyl or cyano group or a salt of a carboxyl group) other than in the ortho position to the phenolic hydroxyl group. The stabilizer may be added to the polyamide or to the polyamide forming ingredients before or during polymerization. The carboxyl group (or group derived therefrom) may be directly attached to the phenolic nucleus or separated therefrom by one or more carbon atoms. The hydrocarbon group may be a tertiary alkyl radical. Typical stabilizers have the formula R 1 is a tertiary alkyl, aralkyl or cycloalkyi group; R 2 is an alkyl, cycloalkyl, aryl, aralkyl or alkoxy group or a group A-X in which A is a direct link or an alkylene radical and X is carboxyl, carbamyl, carboxylic ester or cyano group; R 3 is either a group A-X as set out above or a group where A is an alkylene radical and X and X<SP>1</SP> are carboxyl, carbamyl, carboxylic ester or cyano groups which may be the same or different. Examples of suitable phenols are: 3,5- di - tert. - butyl - 4 - hydroxybenzoic acid and # - (4 - hydroxy - 3,5 - di - tert. - butylphenyl)- propionic acid. The carboxyl group(s), or group(s) derived therefrom is preferably sufficiently labile to take part in the condensation reaction. The stabilizers may be used at 0À01- 5% by wt. of the polyamide. In addition to the phenolic stabilizer there may also be present a phosphorus acid: in which X is H, OH or an aliphatic, cycloaliphatic, araliphatic or aryl radical or a salt or ester of such an acid. Examples of suitable phosphorus compounds which may be used at 0À01-2% by wt. of the polyamide are phosphorous and phosplionous acid or salts thereof with an amine, sodium hypophosphite, hexamethylene diammonium hypophosphite and sodium phenyl phosphite. Examples relate to the stabilization of nylon 6.6 in which the stabilizers are added at the start of the polymerization.