Laminat af metalplader med svingningsdæmpende, selvhæftende mellemlag indeholdende en vinylacetattetrapolymer

1,246,997. Vibration damping laminates. FARBWERKE HOECHST A.G. 4 Dec., 1968 [6 Dec., 1967], No. 57606/68. Heading B5N. [Also in Divisions B2 and C3] A vibration damping laminated system comprises two plates, e.g. of metal such as steel, bonded together with an interlayer comprising a graft polymer of 40-80% by weight of a equimolar mixture of styrene and acrylonitrile on 60-20% by weight of a copolymer of 30-40% by weight of vinyl acetate, 30-40% by weight of 2-ethylhexyl acrylate, 10-30% by weight di-n-butyl maleate and 5-15% by weight of a copolymerizable unsaturated caroxylic acid, e.g. crotonic acid. The graft polymer may be cross-linked with a compound containing a plurality of epoxide or isocyanate groups. The graft polymer may contain minor amounts of fillers, e.g. heavy spar, silicic acid, graphite, soot or a mixture thereof, and one or more plasticizers. The total thickness of the laminated system may be 1-6 mm., the thickness of the interlayer being 0À1-1 mm. and the ratio of the thickness of the plates being from 1 : 1 to 4 : 1. The graft polymer may be applied to the plates by trowelling, brushing or pouring at an elevated temperature and the system cooled under pressure between rollers. A solution of the copolymer in the mixture of styrene and acrylonitrile containing a polymerization initiator, e.g. tertiary butyl hydroperoxide, may be applied between the plates and the laminated system subjected to heating at 60-180‹ C. to effect grafting.