METHOD FOR PRODUCTION OF MOULDING SOUND-ABSORBING MATERIAL Russian patent published in 2003 - IPC

FIELD: sound proofing of buildings and vehicles. SUBSTANCE: method is based on milled urethane foam mainly of the open-type porous structure with a density of 15-70 kg/cu.m passing through a screen with mesh of 7 mm, it consists in its mixing with the binder, mechanical packing in a mould to a density of 100-160 g/cu.m, then - hardening of the packed material at a temperature of 130-150 C for 15-25 min. Urea-formaldehyde resin is used as binder with the relation of ammine and formaldehyde groups equal to 1:0.8, modified by melamine, with the content of melamine from 1-100 mg, and by diethyleneglycol with the content diethyleneglycol within 1-20 mg for 100 mg of polymer, with a hardening catalyst, or 45-50-% aqueous dispersion of acrylic copolymer with relation of methyl methacrylate: butylcrylate: methacrylic acid = 15:80:5 mas.%, or 45-80-% aqueous dispersion of polyvinyl acetate modified by epoxy oligomer taken within 70-100 mg for 100 mg of polyvinyl acetate. The binder is taken within 10-55 mas.%. Used as the hardening catalyst is a 25-% aqueous solution of ammonium chloride at a relation resin: catalyst = 97:3 mas.% in terms of a dry substance. The material may include particles of milled natural or synthetic fibre and/or polyethylene terephthalate film passing through a screen with a mesh of 7 mm, 1-20 mas.% for 100 mas.% of milled urethane foam. The material sound-absorbing factor within a frequency range from 800 to 6300 Hz makes up to 0.20-0.95. EFFECT: expanded range of sound-absorbing materials. 3 cl, 1 tbl