| 摘要 |
In a process for making microporous compositions and films by dispersing finely-divided thermoplastic particles throughout an inert, incompatible matrix medium, heating to a temperature sufficient to fuse the particles, and then extracting the matrix medium from the formed composition, the matrix medium comprises at least two mutually incompatible and inert matrix substances which are in a viscous state at the temperature used to fuse the thermoplastic particles. Specified thermoplastic particles are of polyvinyl chloride, polyvinyl chloride-acetate, polyvinylidene chloride, polyethylene, polystyrene, polymethyl methacrylate, polyvinyl acetate, polytrifluoromonochloroethylene, butadiene-styrene, butadiene-acrylonitrile, chlorinated rubber, polyamides, ethyl cellulose, cellulose acetate and nitrocellulose. Multiple matrix components specified are siloxane polymers, e.g. polymethyl siloxane oils with "Piccopale" (a petroleum resin which is a polymerization product of a mixture of dienes and olefins) or "Piccopale" with sperm oil. The matrices are usually leached out of the microporous composition by a solvent, e.g. tetrachloroethylene. The dispersion may be formed by admixing the thermoplastic particles and the matrix medium with water or glycerine, or a mixture thereof. Specification 789,882 is referred to.ALSO:In a process for making microporous compositions and films by dispersing finely divided thermoplastic particles throughout an inert, incompatible matrix medium, heating to a temperature sufficient to fuse the particles, and then extracting the matrix medium from the formed composition, the matrix medium comprises at least two mutually incompatible and inert matrix substances which are in a viscous state at the temperature used to fuse the thermoplastic particles. Specified thermoplastic particles are of polyvinyl chloride, polyvinyl chloride-acetate, polyvinylidene chloride, polyethylene, polystyrene, polymethyl methacrylate, polyvinyl acetate, polytrifluoromonochloroethylene, butadiene-styrene, butadiene-acrylonitrile, chlorinated rubber, polyamides, ethyl cellulose, cellulose acetate and nitrocelluloses. Multiple matrix components specified are siloxane polymers e.g. polymethyl siloxane oils with "Piccopale" (a petroleum resin which is a polymerisation product of a mixture of dienes and olefines) or "Piccopale" with sperm oil. The matrices are usually leached out of the microporous composition by a solvent e.g. tetrachloroethylene. The dispersion may be formed by admixing the thermoplastic particles and the matrix medium with water or glycerine, or a mixture thereof. Specification 789,882 is referred to. |
