| 摘要 |
Aqueous polymer dispersions which comprise polyvinyl chloride, from 10 to 100 parts by weight of polystyrene per 100 parts by weight of polyvinyl chloride, and a plasticizer. Plasticisers specified are di-n-propyl and di-n-butyl phthalates, and tricresyl and triphenyl phosphates. The dispersions may be made by mixing a dispersion of polyvinyl chloride with a dispersion of polystyrene which separately may be made by known processes. The plasticiser may be incorporated either with the polyvinyl chloride dispersion or the polystyrene dispersion separately or it may be incorporated with both dispersions separately. Or it may be incorporated with the combined dispersions after mixing. Thickening agents such as proteins, salts of alginic acid, natural gums and resins, and alkali metal salts of polyacrylic acid, generally in proportions between 0.1 and 5 parts per 100 parts of nonaqueous material in the dispersion, may be added. The dispersions are especially suitable for the production of hollow-shaped articles by a dipping process. A former of glass or porcelain is immersed in the dispersion, withdrawn, dried and backed. The coating is then removed from the former. A series of coats may be applied to the former. In examples: (1) an aqueous dispersion of polyvinyl chloride and the sodium salt of sulphonated oleic acid is mixed with an aqueous dispersion of polystyrene and the above salt, water added and stirred. An aqueous paste of the sodium salt of sulphated sperm oil alcohol and dibutyl phthalate is added, stirred, heated and strained. Finally, an aqueous syrup of ammonium polymethacrylate is added. Formers are immersed in this, withdrawn, dried and heated. This may be repeated several times; (2) an aqueous dispersion of polyvinyl chloride, dibutyl phthalate, the sodium salt of castor oil fatty acids, sodium stearate, and the sodium salt of sulphonated oleic acid are mixed with an aqueous dispersion of polystyrene and the sodium salt of sulphonated oleic acid. An aqueous syrup of ammonium polymethacrylate is added and the treatment of example (1) applied. Specifications 410,132, 494,772, 573,366, 575,901 and 577,317 are referred to. |
