THERMOPLASTIC RESIN FOAM

摘要

PROBLEM TO BE SOLVED: To obtain a thick thermoplastic resin foam with a high expansion ratio and closed cell content. SOLUTION: This foam is produced from a thermoplastic resin (pref. a polypropylene resin) having such a relaxation modulus G(t) measured at 180 deg.C that it is expressed by the formula: G(t)=σ(t)/6 [whereinσ(t) is the stress (dyn/ cm<2> ) after being kept for t (sec) under a shear strain of 6], that G(T) at t=10<-1> sec is 10<4> -10<6> dyn/cm<2> , and that G(t) at t=10 sec is 1.5×10<3> -10<5> dyn/cm<2> .