Polyamide and polyolefin composite article prodn. - by successive injection into mould, using grafted polypropylene as adhesion aid

摘要

A laminated structure comprising a polyolefin core sheathed in a polyamide skin is produced by first injecting the polyamide compn. into a mould and, prior to solidification of the central zone of the compn., injecting the polyolefin into the mould to cause expansion or spreading of the polyamide towards the mould cavity periphery. Into either of the two polymers is incorporated (1) a (co)polypropylene grafted with an unsatd. dicarboxylic acid or anhydride and opt. (2) >=1 cpd(s) chosen from aromatic monocarboxylic acids, OH-contg. monocarboxylic acids which can form a cyclic anhydride, polycarboxylic acids with is not >4 COOH gps. and is not >1 atom of an element other than C, H and O, and their anhydrides. The grafted copolymer (I) contains >=1 wt.% of C=O in the acid or anhydride gps. of (I) and in the free acid or anhydride, the amt. of (I) is 20 wt.%, based on the polymers of the compn., and is such that, together with the free acid or anhydride, the compn. contains 0.02-1% wt., based on the polymers, of acid and/or anhydride gps. (expressed as C=O). (I) together with the free acid ensures good adhesion between the polyolefin and the polyamide and does not have to be separately injected.