Foamed plastics mouldings with textured surface - using org complexing agent as inhibitor to prevent premature foaming

摘要

Foamed plastics with a relief structure are made by foaming plastics matls. contg. a heat-decomposable blowing agent and heavy metal cpd., in the presence of an org. complexing agent for heavy metals as inhibitor. Presence of inhibitor prevents pre-activation of the blowing agent by heavy metal cpds. present in the compsn., without giving rise to decompsn. prods. or to coloured by-prods. which would discolour the foamed prod. The plastics compsn. may be e.g. based on polyethylene, polypropylene, polyvinyl acetate, polystyrene, ABS and (esp.) plastiised PVC. The blowing agent may be e.g. azodicarbonamide, azoisobutyrodinitrile, benzosulphohydrazide, dinitrosopentamethylenetetramine, etc. Activators such as lead carbonate, zinc octoate, etc., may be added, while the compsn. may also contain heavy metal cpds. as stabilisers, etc. The org. complexing agent may be added e.g. at 5-30 wt% on thee plastics matl., and may be e.g. thiourea, quinaldic acid, toluyltriazole, the di Na salt of ethylenediaminetetra-acetic acid, hydroxyquinoline, etc.