| 摘要 |
The production of expanded thermoplastic resin sheets having a continuous non-porous surface involves fusing, at least partly a mixture of a thermoplastic resin having a fluxing temperature of 150-185 DEG C. and a blowing agent, e.g. azodicarbonamide having a decomposition temperature of at least 190 DEG C., calendering the mixture at 150-185 DEG C. to a coherent film of thickness 0,001 to 0,15 inch, and subsequently heating the film to a temperature of 190-255 DEG C. for 5-60 seconds to decompose the blowing agent without rupturing the film. The product has a continuous unbroken surface. The resins referred to are homopolymers of vinylchloride and copolymers of vinyl chloride with vinyl acetate, vinylidene chloride and diethyl maleate, graft polymers of styrene and acrylomitrile or polybutadiene or GR-S, mixtures of resins with rubbery materials e.g. polyvinyl chloride and/or styrene-acrylomitrile resin with GR-S or nitrile rubber. Modifiers such as phenolic resins and fillers, flock, pigments, plasticisers, softeners stabilizers and anti-oxidants may be incorporated. An example of a suitable formulation is 100 parts polyvinyl chloride, 80 parts dioctylphthalate (plasticiser), 1 part barium-cadmium laurate, 1 part diphenylphosphite, 1 part epoxidised glycidyl ether, 0,5 parts stearic acid (stabilizers) and 15 parts of azodicarbonamide. The fused mixture may be combined with sheets of another plastic, fabric or wood before blowing.ALSO:The production of expanded thermoplastic resin sheets having a continuous, non-porous surface involves fusing, at least partly, a mixture of a thermoplastic resin having a fluxing temperature of 150-185 DEG C and a blowing agent, e.g. azodicarbonamide, having a decomposition temperature of at least 190 DEG C, calendering the mixture, while maintaining the temperature at 150-185 DEG C, to a coherent film of thickness 0,001 to 0,15 inch, and subsequently heating the film to a temperature of 190-255 DEG C. for 5-60 seconds to decompose the blowing agent without rupturing the film. The product has a continuous unbroken surface. The resins referred to are homopolymers of vinyl chloride and copolymers of vinyl chloride with vinyl acetate, vinylidene chloiode and diethyl maleate, graft polymers of styrene and acrylonitrile on polybutadiene or GR-S, mixtures of resin with rubbery materials, e.g. polyvinyl chloride and/or styrene-acrylonitrile resin with GR-S or nitrile rubber. Modifiers such as phenolic resins, and fillers, flock, pigments, plasticizers, softeners, stabilizers and antioxidants may be incorporated; an example of a suitable formulation is: 100 parts of polyvinyl chloride with 80 parts of the plasticizer dioctyl phthalate and 3,5 parts of the stabilizers barium-cadmium laurate, diphenyl phosphite, epoxidated glycidyl ether and stearic acid, and 15 parts of azodicarbonamide. The fused mixture may be combined with sheets of another plastic, fabric or wood before the blowing. U.S.A. Specifications 2,666,036 and 2,763,475 are referred to. |
