SOUND-ABSORBING MATERIAL BASED ON CLOSED-CELL NEEDLE-PUNCHED FOAMED POLYETHYLENE AND A METHOD FOR MANUFACTURE THEREOF Russian patent published in 2007 - IPC C08J9/00 E04B1/82 B60R13/08 G10K11/16 

FIELD: polymer materials.

SUBSTANCE: invention relates to sound-absorbing materials for noise insulation of a motor car and its parts within frequency range 1600 to 5000 Hz, e.g. cowl, front guard, doors, as well as agricultural technics, mechanical engineering and construction pieces wherein efficient sound absorption is required and, in particular, wherein these requirements are coupled with requirements concerning low water uptake. Material according to invention is made as follows. Foamed polyethylene having density 40±15 kg/m³ and thickness 5-10 mm, prepared through extrusion from high-pressure polyethylene with melt flowability index 1.5-2.5 g/10 min, is punched with needles 1.8-2.2 mm in diameter at punch rate 10-14 cm^-2. Further, glue layer is applied on the needle-entry side.

EFFECT: enhanced sound-absorbing properties of material, reduced dynamic modulus of elasticity, and preserved low water uptake level.

4 cl, 4 tbl, 4 ex