DAMPING SHEET FOR RESTRICTION TYPE DAMPING STRUCTURE AND VISCOELASTIC MATERIAL FOR FORMING THE SAME SHEET

摘要

PURPOSE:To keep high damping properties within a wide temp. range by consti tuting a three-layer sheet by sandwiching a viscoelastic layer composed of a mixture wherein the ratio of an olefin oligomer and an inorg. filler is specified between both bituminous sheets specified in a thickness and specific gravity to superpose all of them one upon another. CONSTITUTION:A bituminous sheet 1 is based on straight asphalt and has a thickness of 1.0 - 3.0 mm, specific gravity of about 1.6 and softening temp. of about 130 deg.C. A viscoelastic layer 2 is composed of a mixture consisting of 30- 55 pts.wt. of an olefin oligomer and 85 - 150 pts. wt. of an inorg. filler and the viscosity thereof at 140 deg.C is 1,000,000 - 2,000,000 CP and the loss tangent angle thereof takes the max. value at -10 -20 deg.C and the value thereof is 0.3 or more. When a restriction type damping structure 6 is formed by interposing the viscoelastic material having these properties between asphalt sheets as a layer of 100 - 1,000mum, flow-out at high temp. is eliminated and damping properties can be improved.