| 摘要 |
#CMT# #/CMT# Foam comprises thermoplastic polyesters with high homogeneity, low open-cell factor and high elongation at break under shear stress, where dianhydrides of tetracarboxylic acid are used as modifier, and the polyester foam comprises thermoplastic elastomer. #CMT# : #/CMT# Independent claims are included for: (1) a process for producing the foam, comprising mixing a polyester with a pre-mixture of thermoplastic elastomers, preferably thermoplastic copolyester elastomers and dianhydrides of tetracarboxylic acids, and foaming the mixture into a foam; and (2) an agent for producing the foam, comprising a pre-mixture containing 25-95, preferably 80-90 wt.% of thermoplastic elastomers, preferably thermoplastic copolyester elastomer, 5-30, preferably 10-15 wt.% of dianhydrides of tetracarboxylic acids, 0-70, preferably 1-50 wt.% of stabilizers, nucleating agents, flame retardants and/or polyester, preferably a polyester of the same quality as a modifier to the main polyester. #CMT#USE : #/CMT# Used as foam. #CMT#ADVANTAGE : #/CMT# The foam exhibits high homogeneity, low open-cell factor, high elongation at break under shear stress and high density. #CMT#POLYMERS : #/CMT# Preferred Components: The foam contains 0.5-15 wt.% of thermoplastic elastomer, preferably thermoplastic copolyester elastomers. The thermoplastic copolyester elastomer comprises polyester blocks. The polyester blocks from diol, preferably 1,4-butanediol or 1,2-ethanediol, and dicarboxylic acid, preferably terephthalic acid are esterified with polyethers carrying hydroxyl end groups in condensation reaction. The foam contains less than 8, preferably 4% of open cells. The polyester foam has a shear elongation of more than 12%, preferably more than 50%. Preferred Process: The polyester is mixed with a pre-mixture of thermoplastic copolyester elastomer and dianhydrides of tetracarboxylic acids in reactor or mixer, preferably single- or twin screw extruder, multiple-screw extruder or tandem system of two combined single- or twin-screw extruder. #CMT#EXAMPLE : #/CMT# Polyester granulate (96.3 wt.%) was dried for 5 hours at 170[deg] C with dry air. The dried granulate, a premixture (2.7 wt.%) (obtained by drying thermoplastic copolyester elastomer (TPC) in the form of granules for 4 hours at 100[deg] C using hot air, mixing the dried TPC (40-85 wt.%) and pyromellitic dianhydride (15 wt.%) at 200-210[deg] C, heating, cooling and drying the resulting premixture for 3 hours at 70[deg] C) and talcum (1%) were fed into a first extruder, mixed, melted at 248[deg] C, and foamed with carbon dioxide to obtain corresponding foam. |
