Chromate-free resin-composite vibration deadening material

A vibration-deadening material, comprising:

• a multilayer structure comprising an intermediate layer, a first metal sheet, and a second metal sheet, wherein the intermediate layer comprises a viscoelastic resin composition provided between the first metal sheet and the second metal sheet, and wherein:
• (i) the viscoelastic resin composition comprises a thermosetting resin which includes an amorphous copolymerizable polyester resin and a curing agent,
• wherein the amorphous copolymerizable polyester resin includes a polycarboxylic acid chosen from at least one of adipic acid, sebacic acid, dimer acid, hydrogenated dimer acid, or alkenylsuccinic acid in an amount of between approximately 5 mol % to approximately 50 mol % in whole polycarboxylic acid components, the amorphous copolymerizable polyester resin further including aromatic dicarboxylic acid in an amount of approximately 50 mol % or more in the whole polycarboxylic acid components,
• wherein the amorphous copolymerizable polyester resin includes a glass transition point temperature between approximately −40° C. and approximately −10° C.,
• wherein a weight average molecular weight of the amorphous copolymerizable polyester resin is approximately 8,000 or more, a blended amount of the curing agent in the viscoelastic resin is approximately 3 parts by mass to approximately 35 parts by mass or more, with respect to 100 parts by weight of the amorphous copolymerizable polyester resin,
• and wherein the curing agents include at least one types of curing agents selected from the group consisting of polyepoxy compounds, acid anhydrides, and polyisocyanate compounds;
• (ii) a first surface of the first metal sheet and a second surface of the second metal sheet contact the viscoelastic resin composition;
• and
• (iii) each of the first and second surfaces includes a bonding undercoat comprising between about 5 and 50 mass % of silica, between about 5 and 50 mass % of a polyester resin having a glass transition point temperature of approximately 0° C. or greater, between about 1 and 50 mass % of tannic acid, and between about 0 and 30 mass % of a silane coupling agent, and
• wherein the bonding undercoat is essentially free of chromate.