US 7,018,700 B2 · Acoustic absorption polymer foam having improved thermal insulating performance

Abstract

Polymer foams having a good balance of high sound absorption, low thermal conductivity and generally low water absorption are disclosed which are obtainable by perforating (i.e., hole punching) a polymer foam having a moderately large cell size (1.5 mm to 4 mm) and an open content not greater than 40 percent to increase the open cell content of the foam by at least about 10 percent relative to the non-perforated foam, the polymer foam matrix preferably made of a thermoplastic foam, such as a low-density polyethylene (LDPE) resin, a high melt strength (HMS) polypropylene resin (PP), or a blend of an HMS PP resin and an LDPE resin, optionally containing a cell size enlarging agent such as glycerol monostearate, an antioxidant, carbon black and/or flame retardant additives, using a volatile organic compound, e.g. isobutane, as blowing agent. These foams are useful for applications in which a combination of acoustic absorption, thermal insulation and possibly low water absorption is needed, such as outdoor, motor vehicle and marine applications. They exhibit a noise reduction coefficient greater than 0.3, a thermal conductivity not greater than 90 mW/m° K measured at an average temperature of 10° C. according to DIM52616 and a low (less than 10, such as less than 1.5, percent by volume) water absorption when measured according to EN 12088 at a 50° C. temperature gradient for an exposure test period of 14 days.

Claims18

Dependent claims

A method for making cellular acoustic absorption polymer foam having improved thermal insulating performance comprising:

(A) Providing a polymer foam having an average cell size in the range from 1.5 mm to 4 mm and an open cell content not greater than 40 percent measured according to ASTM D2856, Procedure A, and
(B) Perforating the polymer foam provided in step (A) at a surface of the polymer foam to form a multiplicity of perforation channels extending from that surface into the polymer foam such that the open cell content of the foam measured according to ASTM D2856, Procedure A, is increased relative to the step (A) polymer foam by at least 10 percent to obtain a perforated polymer foam having an open cell content of at least 20 percent, measured according to ASTM D2856, Procedure A,
wherein the perforating step (B) is carried out such that the number of perforation channels per square centimeter formed by step (B), “PD”, has a value defined by equation (I):
PD≧X/(ACS)2 (I)
wherein “ACS” represents the average cell size of the polymer foam provided in step (A) measured in millimeters according to ASTM D3576 and “X” equals 4, wherein PD is at least 30 perforation channels per 10 square centimeters and/or ACS is at least 3 mm.

2 more elements

Dependencies are inferred from the claim text.

Acoustic absorption polymer foam having improved thermal insulating performance

Life of this patent

Acoustic absorption polymer foam having improved thermal insulating performance

Life of this patent

Abstract

Claims18