Abstract: The present invention relates to a viscoelastic resin composition for a vibration damping material and a vibration damping material using the same. The viscoelastic resin composition includes as its main components: Low Tg resin (A) with a glass transition temperature of -60.degree. C. to 0.degree. C. and a number average molecular weight of 5000 to 50000, the Low Tg resin (A) being a polyester containing an acid component having 50 to 90 mol % of aromatic dicarboxylic acid and 10 to 50 mol % of dimer acid, and a glycol component having at least 30 mol % of glycol with an alkyl group as its side chain and the glycol having at least four carbon atoms; and High Tg resin (B) which is at least one selected from the group consisting of amorphous polyester resins, phenoxy resins, and epoxy resins, the epoxy resins having a number average molecular weight of at least 1000, the respective resins having a glass transition temperature in the range of 0.degree. C. to 80.degree. C.

Abstract: There is disclosed a viscoelastic resin composition for vibration damping material containing as essential components a polyester resin having a molecular weight of 5,000 to 50,000 and an acid value of 50 to 500 equivalents/10.sup.6 g, at least 80 mol % of the polycarboxylic acid component of which is an aromatic dicarboxylic acid and, at least 30 mol % of the polyol component of which is a compound of the formula (I):H--(OR.sub.2).sub.n --O--A--R.sub.1 --A--O--(R.sub.2 O).sub.n --H(I)wherein R.sub.1 is oxygen or a straight or branched chain C.sub.1-6 alkylene group; R.sub.2 is a straight or branched C.sub.1-6 alkylene group; A is a group of the formula: ##STR1## (wherein R.sub.3 is hydrogen or a C.sub.1-6 alkyl group); and n is an integer of 1 to 6, an acid anhydride compound having at least two acid anhydride groups in a molecule, and an epoxy compound having at least two epoxy groups in a molecule.

Abstract: Disclosed herein is a viscoelastic resin composition for vibration-damping material which comprises (A) at least one amorphous polyester resin of low specific gravity in which more than 40 mol % of the dibasic acid moiety is of aromatic type, (B) at least one amorphous polyester resin of high specific gravity in which more than 80 mol % of the dibasic acid moiety is of aromatic type, and (C) at least one hardener selected from the group consisting of polyisocyanate compounds, epoxy group-containing compounds, and acid anhydrides, said consitutents (A) and (B) being in the ratio of from 90:10 to 30:70 by weight and differing from each other in specific gravity (at 30.degree. C.) by 0.06 to 0.15 and also in molecular weight by more than 10000, with that of either of them being higher than 5000. This resin composition gives a vibration-damping material which exhibits improved vibration-damping properties, adhesive strength, formability, and heat resistance after forming.

Abstract: The use of an amorphous block copolyester resin as a viscoelastic resin for a composite vibration damping material, and a viscoelastic resin composition for a composite vibration damping material which comprises the amorphous block copolyester resin and at least one compound selected from the group consisting of polyepoxy compounds, polyisocyanate compounds and acid anhydrides.