GB569073A - Improvements in or relating to the manufacture of shaped articles from synthetic linear polyamides - Google Patents

Abstract

Articles are made by shaping a gel comprising a polyamide or a polyesteramide and a mixed organic solvent containing an alcohol and an aromatic hydrocarbon or a chlorinated hydrocarbon, and then removing the solvent from the shaped gel. The gels are made by refluxing the polyamide, with stirring, with the solvent mixture, sometimes under pressure, or by soaking the polyamide in an amount of solvent mixture insufficient to give a solution. Preferably, the solvent mixture contains 50-90 per cent by volume of an alcohol boiling below 210 DEG C., and 10-50 per cent by volume of the aromatic or chlorinated hydrocarbon boiling below 210 DEG C. The polyamide amounts to 20-80 per cent of the total weight of the gel, and preferably 25-50 per cent. The solvent mixture comprises preferably 65-75 per cent methanol or ethanol by volume, and 25-35 per cent benzene. Polyamides used include interpolyamides prepared by customary methods, simple polyamides prepared according to usual methods (cf. Specifications 461,236 and 461,237), for example, from 12-aminostearic acid, from 2 : 5-dimethylhexamethylenediamine and a a 1-dimethyl adipic acid, and from 3 : 31-diamino-dipropyl ether and adipic acid, modified polyamides obtained by reacting a solution of a polyamide in formic acid with formaldehyde and an alcohol, polyamides formed from a monoaminomonohydric alcohol and a dibasic carboxylic acid, and polyesteramides formed from, for instance, glycol-dibasic acid mixtures or hydroxy acids and polyamide-forming reactants. Alcohols specified are propyl, isopropyl, butyl, isobutyl, furfuryl, benzyl, alkyl, and cyclohexyl alcohols, and ether alcohols such as b -methoxy ethanol. Other components specified are benzene, toluene, xylene, styrene, chloroform, trichlorethylene, methylene chloride and ethylene dichloride. Materials or fillers which may be incorporated with the gels are phenol-aldehyde or sulphonamide-formaldehyde resin, thiocyanates, halides, sulphates, phosphates, pigments such as titanium dioxide or carbon black, barium sulphate, plasticizers, crown clay, calcium phosphate. The soluble inorganic salts may be removed by leaching in water after forming of the gel. The gels can be shaped in injection and compression moulding machines, milled, calendered, or stuffed, or used to prepare collapsable tubes by impact extrusion methods, or to prepare laminated products. In examples: (1) an interpolyamide prepared from hexamethylene diammonium adipate hexamethylene diammonium sabacate, and caprolactam is refluxed with stirring with an ethanol-toluene mixture. Bars moulded from the gel obtained collapse on loss of solvent to bars of smaller dimensions, and the gel is moulded as a conical cup to form a covering for a shoe heel which is shrunk on the heel by loss of solvent, or moulded with smaller dimensions than the heel, blown with hot air, and shrunk on by loss of heat. (2) A gel similar to that of example (1) is formed into sheeting. (3) An interpolyamide prepared from hexamethylene-diammonium sebacate and adipate is heated under pressure and with agitation with a methanol-chloroform mixture. The gel obtained is worked into sheeting on a rubber mill. (4) The gel of example (1) is worked into tubing on a Royle screw stuffer. Crown clay or a thiocyanate (e.g. sodium, calcium, ammonium, lithium, or barium) may be incorporated with the gel, and the thiocyanate may be subsequently removed by leaching with water. (5) The interpolyamide of (3) above is gelled with cyclohexanol and chloroform and worked into sheet form on rolls. Specification 542,444 also is referred to.