Flat, fibre-reinforced composites with thermoplast matrix - have thin outer zone of similar but higher mol.wt. thermoplast

摘要

Composites (I) with matrix of thermoplast (II) have in at least one outer zone a polymer of same basic type as (II), with mol.wt. at least 10% higher and 1-250 microns thick. Mfr. is continuous or discontinuous prepn. Textile reinforcing fibre article is preimpregnated or impregnated with a (II) and at least one surface layer of same basic type as (I) is applied simultaneously or in a second stage, mol.wt. of (I) in outer layer being at least 10% greater than that of (II) in the core. ADVANTAGE - The bond between outer, higher mol.wt. layer and lower mol.wt. core layer is good due to 'solubility' of one (II) in the other, (I) combine advantages of good impregnation of core and relatively short waiting times with favourable properties of higher mol. (II) on surface, i.e. reduced tendency to adhere to metal and to tensile cracking, higher resistance to solvents and other chemicals and greater tolerance to slight mechanical damage.