VIBRATION DAMPING COMPOSITE STRUCTURAL BODY BY INJECTION MOLDING

摘要

PURPOSE:To obtain inexpensively a molded product, which can form a structural body independently and is superior in a vibration damping and soundproof functions, by a method wherein synthetic resin whose modulus of elasticity is low as compared with that of synthetic resin to be used for an outer layer is used for an intermediate layer by a sandwich injection molding method. CONSTITUTION:Polypropylene resin whose modulus of elasticity is high at the normal temperature and injection molding is comparatively easy is suitable for synthetic resin A constituting an outer layer. Ethylene copolymer resin whose synthetic resin B constituting an intermediate layer possesses the low modulus of elasticity as compared with that of the synthetic resin A and the peak value of its tan delta is in a range of -10 deg.C-80 deg.C and its value is 0.3 or more is preferable. Out of copolymer such as ethylene and vinyl acetate, a matter having a large number of ramifications, the peak value of the tan deltain a viscoelastic value is 0.3 or more and content of copolymeric ingredient is 15wt.% or more is preferable. A sandwich injection molding method is used as a molding for a structural body.