| 摘要 |
Polyvinyl alcohol agglomerates resistant to abrasion and soluble in water without lump formation are prepared by a method wherein a polyvinyl ester is subjected to alcoholysis in methanol and the polyvinyl alcohol so formed, when moist with or suspended in the methanolic liquor is intimately mixed, prior to or during drying, with 1 to 20 weight per cent of a 0.01 to 2% aqueous solution of an emulsifier or wetting agent with continuous mechanical agitation and the mixture is dried at 100 DEG to 200 DEG C. Specified emulsifiers and wetting agents are alkali metal salts of sulphonated alkylbenzenes and alkyl sulphates, and hydroxyethylated alkyl phenols, fatty acids or fatty alcohols. Drying may be effected in a fluidized bed, paddle or flash drier. In examples, sodium dodecylbenzene sulphonate solution is added to a suspension of polyvinyl alcohol in a methanol/methyl acetate mixture and dried in a flash drier under nitrogen. |
