| 摘要 |
A polyvinyl chloride composition comprises polyvinyl chloride, a plasticizer, a pigment, at least 3 per cent of a swellable macromolecular substance which does not dissolve in or react with polyvinyl chloride, and a swelling agent for the macromolecular substance which is either water or an organic liquid which has no solvent action on polyvinyl chloride and volatilizes at the temperature at which the polyvinyl chloride is gelled, said swellable macromolecular substance being present in the composition as discrete particles and said swelling agent being present in the composition in an amount which swells the macromolecular substance but is insufficient to form a dispersion or macromolecular solution therewith. The polyvinyl chloride, plasticizer and pigment may be mixed together and slightly gelled before adding the other ingredients. Macromolecular substances swellable in water include starch, dextrin, pectin, alginates, casein, gelatin, methyl cellulose, cellulose glycollate salts, agar-agar, polyamides, polyvinyl alcohol, polyacrylic and polymethacrylic acid salts. Organic swelling agents specified are methanol, ethanol and benzine. Macromolecular substances swellable in organic solvents are polyvinyl acetate and acetal, polyamides, benzyl cellulose and polystyrene. Up to 10 per cent, preferably 0.2-5 per cent of blowing agents may be included, e.g. ammonium carbonate and bicarbonate, percarbamide, iron oxalate, ethyl malonic acid, citric acid, azodibutyric acid nitrile, o- and m-benzoic acid, n-azoxy-benzoic acid, benzoyl peroxide, hydrazobenzene, and diaminodiphenylamine. A hydrophilic filler may also be included, e.g. flocks of cotton, staple fibre, artificial silk, paper, wood, cork or leather meal, leather powder, animal hair, bentonite, silica gel. Conventional plasticizers, e.g. dioctyl phthalate, may be partly or completely replaced by acetylated castor oil. The composition may be coated on cotton-twill, then gelled and rendered porous. |
