초록 ▼

An improved closed cell polymer foam and foaming agent involving the use of a hydrogen-containing halocarbon blowing agent (e.g., HCFC-22) in combination with an effective amount of a hydrogen bond forming blocking agent (e.g., organic ether, ester or ketone). The presence of the blocking agent is s

An improved closed cell polymer foam and foaming agent involving the use of a hydrogen-containing halocarbon blowing agent (e.g., HCFC-22) in combination with an effective amount of a hydrogen bond forming blocking agent (e.g., organic ether, ester or ketone). The presence of the blocking agent is shown to significantly reduce the escape of blowing agent from and entry of air into the foam resulting in low thermal conductivity over a longer period of time and improved thermal insulation value. A closed cell thermoplastic foam such as polyethylene, polypropylene, polystyrene, among others, is disclosed produced by means of an environmentally friendly nonflammable blowing agent substantially free of halogen substituents other than fluorine and comprising HFC-134 (1,1,2,2-tetrafluoroethane).

대표청구항 ▼

[ What is claimed is:] [1.] A method for preparing a non-flammable insulating thermoplastic foam body comprising the steps ofa) providing a first molten composition of thermoplastic resin,b) introducing an effective quantity of a blowing agent composition, said blowing agent composition comprising a

[ What is claimed is:] [1.] A method for preparing a non-flammable insulating thermoplastic foam body comprising the steps ofa) providing a first molten composition of thermoplastic resin,b) introducing an effective quantity of a blowing agent composition, said blowing agent composition comprising at least 70 weight percent 1,1,2,2 tetrafluoroethane and no components having halogen substituents other than fluorine into said first molten compositionc) dispersing said blowing agent composition throughout said first molten composition to form a second molten composition; andd) extruding said second molten composition through a die from a region of high pressure to a region of low pressure such that said second molten composition foams upon extrusion through said die to form a closed cell thermoplastic foam body having a density of about 0.75-15 pounds per cubic foot (12 to 240 kilograms per cubic meter) and having cells of an average cell size of 0.1-1.5 mm.