GB830799A - Improvements in and relating to the preparation of synthetic fibre-forming polyamides and polyamides prepared thereby - Google Patents

Abstract

Synthetic fibre-forming polyamides are made by condensing an aliphatic normal diprimary diamine having four to ten carbon atoms, a lower dialkyl ester of isocinchomeronic acid and a lower dialkyl ester of an aliphatic dicarboxylic acid having two to ten carbon atoms, by reacting at a temperature of 50 DEG to 150 DEG C. and than at a temperature of 200 DEG to 300 DEG C., under reduced pressure, the mols. of diamine being equal to within \sB 5 mol. per cent to the sum of mols. of isocinchomeronic acid ester and mols. of aliphatic dicarboxylic acid ester, and the molar ratio of isocinchomeronic acid ester to aliphatic dicarboxylic acid ester being in the range 30:70 to 80:20. Lower alkyls are defined as methyl, ethyl, propyl or butyl. The polymers may be made by condensing the three components together or by condensing the diamine with one of the components and then with the remaining reactant. Reaction solvents specified are methanol, ethanol, butanol, and acetone. Specified diamines are tetra-, penta-, hexa-, hepta-, octa-, nona- and decamethylene diamine. Specified dicarboxylic acids are oxalic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic and sebacic acid. Viscosity stabilizers, e.g. aliphatic or aromatic alkyl esters, may be present in the reaction mixture. The products of the invention may be heated to temperatures 30 DEG C. above their melting-points and drawn into filaments, the filaments being drawn in hot water or air heated to 100 DEG to 150 DEG C. to three or four times their original length and annealed at 220 DEG C. for about 30 minutes. In the examples: (1) dimethyl isocinchomeronate, dimethyl adipate and hexamethylene diamine are dissolved in ethanol and heated firstly under reflux and then at 255 DEG to 265 DEG C. under reduced pressure to give a polyamide; (II) hexamethylene diamine and dimethyl isocinchomeronate are heated under reflux in ethanol, the product being reacted with diethyl oxalate to form a pre-polymer which is further heated at 235 DEG to 240 DEG C. to form a polyamide; (III) the 2-component prepolymer of Example (II) is refluxed with dimethyl adipate in ethanol, the resultant prepolymer being heated at 260 DEG to 270 DEG C. to give a polyamide; (IV) diethyl malonate and hexamethylene diamine are refluxed in methanol, dimethyl isocinchomeronate and methanol are added and the mixture refluxed and then heated under reduced pressure; (V) hexamethylene diamine and dimethyl adipate are refluxed with methanol, dimethyl isocinchomeronate is added and the refluxing continued to give a prepolymer which is further condensed by heating in the presence of nitrogen at 250 DEG to 275 DEG C. under reduced pressure; (VI) is similar to (V) but with the addition of methyl benzoate during the second reflux; (VII) tetramethylene diamine and dimethyl adipate are refluxed in ethanol, dimethyl isocinchomeronate is added and the mixture is refluxed and condensed under reduced pressure to form a polyamide; (VIII) decamethylene diamine and diethyl sebacate are refluxed in butanol, dimethyl isocinchomeronate is added and the mixture refluxed and then heated to form a polyamide; (IX) decamethylene diamine and dimethyl adipate are refluxed in ethanol, dimethyl isocinchomeronate is added and the mixture refluxed and then heated to form a polyamide; (X) hexamethylene diamine, dimethyl azelate and dimethyl isocinchomeronate are refluxed in methanol, the methanol evaporated off and the product heated to form a polyamide; (XI) hexamethylene diamine and dimethyl isocinchomeronate are refluxed in ethanol, diethyl oxalate is added and the mixture condensed to form a polyamide; and (XII) tetramethylene diamine and dimethyl azelate are refluxed in ethanol, dimethyl isocinchomeronate is added and the mixture heated to form a polyamide. The products of the examples are (I) to (III), (V) to (VII) and (IX) to (XII) spun into filaments, the filaments being (V) and (VI) drawn in boiling water and heated under strain in air at 150 DEG C.; (VII) drawn in a water bath at 80 DEG C. and heated in air at 150 DEG C.; and (XI) drawn in a water bath at 60 DEG C. and heated at 150 DEG C.