Viscoelastic resin composition or vibration damping material

A viscoelastic resin composition useful for vibration damping material which comprises:

• (a) a polyester resin having a molecular weight of 5,000 to 50,000, an acid value of 50 to 500 equivalents/10.sup.6 g, a polycarboxylic acid component, at least 80 mol % of which is an aromatic dicarboxylic acid, and a polyol component, at least 30 mol % 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 chain C.sub.1-6 alkylene group;
• A is a group of the formula:
• ##STR3## wherein R.sub.3 is hydrogen or a C.sub.1-6 alkyl group;
• and n is an integer of 1 to 6, and at most 70 mol % of the polyol component of which is at least one polyol selected from the group consisting of ethylene glycol, neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, reductant of dimer acid, eicosanediol, 8,13-methyleicosanediol, 3-methylpentanediol, trimethylpentanediol and cycloaliphatic polyols,
• (b) an acid anhydride compound having at least two acid anhydride groups in a molecule,
• (c) an epoxy compound having at least two epoxy groups in a molecule, and
• (d) a ring-opening catalyst of the epoxy group,
• said composition having a gel fraction of at least 50% by weight when in the form of a coating having a thickness of not more than 100 .mu.m after drying at 180.degree. C. for 3 minutes.