METHOD FOR THE DIRECT BACKFOAMING OF ABSORBER SYSTEMS

摘要

A very low density sound absorbing layer(2) is covered on the back foaming side with a cover layer(3) which prevents foam penetration and is placed in a foam molding tool. Pressure is increased in the absorber layer in the closed tool via the non back-foamed side before the back foaming stage occurs. Pressure is applied by a gas, in particular compressed air. Applied pressure is 0.5-7 bar, in particular 1-3 bar. The cover layer(3) on the back foaming side is either a fleece or film. The sound absorbing layer(2) may be an open cell or part open cell foam with a density of 5-38kg/cu m or a molded cold foam with a density of 35-190kg/cu m and a foam blocking cover layer. A further alternative absorbing layer comprises a non-compressed fleece with a foam blocking cover layer on the back foaming side. Pressure increase is controlled by valves before and during the foaming stage. An Independent claim is included for an absorber system comprising a foam or fleece layer with a cover layer(3,4) on one or both sides and a back foam layer(5).