Foaming propylene copolymer, and foamed particles and foams thereof

Abstract

Provided are a foaming propylene-ethylene random copolymer which is characterized in that (1) its ethylene unit content [x (wt. %)] falls between 0.2 and 10% by weight, (2) its MI falls between 1 and 16 g/10 min, (3) its boiling diethyl ether extraction [E (wt. %)] and x satisfy the relation of a formula (I): E.ltoreq.0.25x+1.1 (I), (4) its melting point [Tm (.degree. C.)] and x satisfy the relation of a formula (II): Tm.ltoreq.165-5x (II), (5) its isotactic triad fraction in the PPP chain moiety as measured through .sup.13 C.ltoreq.NMR is not smaller than 98 mol %, and preferably, (6) the relation between the time of relaxation .tau. (sec) of the copolymer and MI of the copolymer satisfies a formula (III): .tau..ltoreq.0.80-0.42.times.log MI (III), and also its foaming beads and cellular articles. The copolymer and its foaming beads have improved primary and secondary foamability, and the cellular articles of the copolymer have excellent mechanical properties including rigidity.

Dependencies are inferred from the claim text.