Shelf-stable ethylene-.alpha.-olefin (diene) elastomer powders comprising a release agent and a process for the production thereof

Abstract

A process for producing a shelf-stable ethylene-.alpha.-olefin (diene) elastomer powder which comprises a release agent, comprising grinding crumbs or preliminarily comminuted particles of an ethylene-.alpha.-olefin (diene) elastomer having a green strength of 5-20 MPa and a Mooney viscosity ML (1+4) 100.degree. C. of 50-150, and, prior to, during or after the grinding step, adding 0.5-10 parts by weight per 100 parts by weight of the ethylene-.alpha.-olefin (diene) elastomer, of a release agent which is (a) polyethylene of a density of 0.910-0.975 g/cm.sup.3, a viscosity number of 50-330 cm.sup.3 /g and a melt index of 0.2-50 g/10 min, polypropylene of a density of 0.90-0.910 g/cm.sup.3, a viscosity number of 100-1000 cm.sup.3 /g and a melt index of 0.1-50 g/10 min, polybutene-1 of a density of 0.910-0.975 g/cm.sup.3, a viscosity number of 100-1000 cm.sup.3 /g and a melt index of 0.1-100 g/10 min, polyvinyl chloride of a viscosity number of 50-200, all having an average secondary particle size of 5-50 .mu.m; (b) a synthetic amorphous silicic acid (SiO.sub.2) having an average primary particle size of 0.01-0.2 .mu.m and an average secondary particle size of 5-35 .mu.m; a naturally occurring silicic acid, at least 65% by weight of which has an average primary particle diameter of <5 .mu.m and an average secondary particle size of 7-50 .mu.m; or a silicic-acid-containing mineral having an average primary particle size of 0.5-2.5 .mu.m and an average secondary particle size of 10-35 .mu.m; or (c) a carbon black with an average primary particle size of <0.3 .mu.m.

Dependencies are inferred from the claim text.