Dow Global Technolgoies LLC

Sandrine Burgun

Suresh Subramonian

Chung Poo Park

William Gerald Stobby

Jonathan Kammerer

Foam a polymer blend of (a) a high melt strength polypropylene (HMS PP); (b) a linear or substantially linear polypropylene that has a melting point within ten degrees Celsius of (a), a melt flow rate that is significantly different than (a) and that is miscible with (a); and, optionally, (c) a polyethylene that is immiscible with (a) produces a polymeric foam having an average cell size of at least four millimeters and that has an inherent open-celled content of at least 40 percent. The HMS PP makes up 60 weight percent (wt %) or more and 90 wt % or less of the total combined weight of (a) and (b). Component (c) makes up 60 wt % or less of the total polymer blend weight.

Inherently open-celled polypropylene foam with large cell size

A macrocellular foam is described having improved cell size and Fire-test-response Characteristics, among other features, which is obtained by selecting a particle size less than 1 micron for the flame retardant adjuvant. The inventors found that the amount of fire retardant adjuvant can be increased for a given foam cell size or the foam cell size can be increased for a given amount of fire retardant adjuvant, allowing the production of foams having exceptionally large, well-formed, cells that have excellent Fire-test-response Characteristics. The benefits are especially noteworthy in relation to thermoplastic foams and inorganic flame retardation adjuvants, due to the unexpected reduction in the nucleation effect of the adjuvant. The foams are useful for improving the acoustic performance of products that are required to meet certain Fire-test-response Characteristics. It may be used in automotive and other transportation devices, building and construction, household and garden appliances, power tool and appliance and electrical supply housing, connectors, and aircraft as acoustic systems for sound absorption and insulation.

Fire resistance acoustic foam

Preparation of a macrocellular acoustic foam

Macrocellular polyolefin foams that can withstand temperatures above 110&deg; C. are described for use in sound absorption and insulation applications, especially in elevated temperature and/or moist environments. These foams have a large cell size (&gE;1.5 mm), are open or closed-cell foams, and preferably have at least one perforation per square centimeter and/or a density less than 25 kg/m . They are obtainable by extruding a high melt strength (HMS) polypropylene resin (PP), or preferably a blend of a HMS PP resin and a free radical polymerized ethylene polymer present in the blend in a weight ratio of at least 35:65, optionally another polymer such as a substantially random interpolymer, a cell size enlarging agent such a glycerol monostearate, an antioxidant, carbon black and/or flame retardant additives, using a volatile organic compound, e.g. isobutane, as blowing agent.

Growing community of inventors

Leutenheim, France

Sandrine Burgun