| 摘要 |
Particles of polyvinyl chloride, coated with an insoluble layer of condensation resin, are produced by adding to an aqueous polymer latex made by the emulsion polymerization of vinyl chloride, at least one water-soluble aldehyde, e.g. formaldehyde, and at least one watersoluble compound capable of forming thermoset resins therewith, e.g. urea, thiourea, aminotriazines such as melamine, phenols such as monohydroxybenzene, cresols, xylenols, resorcinol and naturally occurring phenols such as quebracho tannin, and reacting to form an insoluble resin on the surface of the particles in the latex. In a modification of the process at least one water-soluble condensation product of an aldehyde and aldehyde reactable compound is introduced into the latex and reacted to form the insoluble coating. Latices of copolymers of vinyl chloride with vinyl acetate or vinylidene chloride may be used in place of the polyvinyl chloride latex. An improvement in certain physical properties, e.g. tensile strength and impact strength, of natural and synthetic polymers such as natural and synthetic rubbers and polyvinyl chloride results when these have incorporated in them the coated polymer particles described above. The incorporation is preferably carried out by latex blending. Such compositions may have plasticizers, stabilizers, pigments and curing agents added to them, and have good chemical and heat resistance, and good electrical and external weathering properties. The products of the invention are adaptable to conversion into shaped articles by the action of heat and pressure. |
