abstract |
A process is provided for preparing a thermoplastic polymer foam, which comprises providing a foamable composition comprising a thermoplastic polymer and a blowing agent, wherein the blowing agent comprises from 10% to 60% by weight of Z-1,1 , 1,4,4,4-hexafluoro-2-butene (Z-HFO-1336mzz) and from 40% to 90% by weight of 1,1-difluoroethane (HFC-152a), and wherein the thermoplastic polymer comprises homopolymer of polystyrene, a polystyrene copolymer, styrene-acrylonitrile copolymer or, or mixtures of these, and that expands the foamable composition to produce a closed cell smooth skin polymer foam, having a density of less than 42 kg / m3 . Also described is a thermoplastic polymer foam composition comprising a thermoplastic polymer selected from the group consisting of polystyrene homopolymer, a polystyrene copolymer, styrene-acrylonitrile copolymer, or mixtures of these, defining a plurality of cells having a average cell size and a blowing agent comprising from 10% to 60% by weight of Z-1,1,1,4,4,4-hexafluoro-2-butene (Z-HFO-1336mzz) and 40% to 90% by weight 1,1-difluoroethane (HFC-152a), which has a density of less than 42 kg / m2, according to the ISO 845-85 method, where the thermoplastic polymer has a flow rate of melt less than 25 g / 10 min. |