| 摘要 |
1,199,534. Flexible porous products. KURASHIKI RAYON K.K. 20 June, 1968 [23 June, 1967], No. 29567/68. Headings C3C and C3P. A flexible porous product is made by immersing in an aq. coagulating bath a composite body comprising (a) a solution of polyvinyl formal (viz. a polyvinyl alcohol wherein 40-90% of the hydroxyl groups have been formalized) in a homogenous aqueous solution of a water-soluble compound, (b) 5-20 parts by wt., per 1 part by wt. of the formal, of a pulverized inorganic material, (c) 0À3-6% by wt., based on the formal, of a metal powder capable of generating hydrogen on reaction with a mineral acid at a temperature of at least 28‹ C. and sufficient mineral acid to react with the metal, the bath being heated to 50-95‹ C., whereby the body is coagulated and foamed by the hydrogen generated, the body being maintained at below 28‹ C. prior to immersion in the bath. The (a) solution may be a solution of the formal in an aq. solution of hydrogen chloride, zinc chloride, acetic acid or formic acid. The inorganic material may be gypsum, calcium silicate, titanium oxide, asbestos or perlite. The metal may be aluminium or zinc. In examples the body was in the form of a sheet and the coagulating bath consisted of an aq. mixture of acetic and sulphuric acids, zinc chloride and sulphuric acid or dioxane and sulphuric acid; or an aq. solution of hydrochloric acid. |
