| 摘要 |
A soil-repellent coating composition comprising silica, polyvinyl alcohol and a wetting agent in an aqueous carrier medium. The composition is characterized in that it, in addition to the aqueous carrier medium, contains 0.5-30% by weight of silica and 0.01-6% by weight of polyvinyl alcohol, and 0.05-2.5% by weight of a wetting agent, based on the total weight of the composition. The ready-made coating composition comprises 0.05-5% by weight of silica, 0.05-0.5% by weight of polyvinyl alcohol and 0.05-0.5% by weight of the wetting agent. The silica is present in the form of an alkali stabilized, preferably ammonium stabilized silica sol with an average particle size of 4-30 nm. The polyvinyl alcohol preferably has a hydrolysis degree of 85-100% and an average molecular weight of 15,000-100,000. The weight ratio of silica to polyvinyl alcohol is above 3:1 and preferably from 5:1 to 40:1. The wetting agent preferably is nonionic. The aqueous carrier medium of the composition may comprise a water-miscible, low-boiling solvent such as ethanol in an amount of up to 20% by weight.
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