| 摘要 |
1,190,785. Sealing composition. DOW CHEMICAL CO. 31 Oct., 1967 [7 Nov., 1966], No. 49441/67. Heading C3P. An opening is sealed against the passage of aqueous fluid by placing in the opening a fluid gelable composition capable of setting autonomously to a water-swellable, resilient solid, the composition comprising water, a watersoluble metal or ammonium salt or mixture of such salts capable of lowering the surface tension of water to a maximum of 12 mols. of Hg, and a water-dispersible synthetic polymer selected from polyvinyl alcohol, polyvinylmorpholinone, polyvinyloxazolidinone, a polyvinylalkyloxazolidinone, polyethylene oxide, a polyvinyltoluene sulphonate, a polystyrene sulphonate, polyvinylpyrrolidone, vinylacetatemaleic acid half amide copolymer, vinylpyrrolidone-maleic anhydride copolymer, and mixtures thereof. Suitable salts are halides, sulphates, acetates, formates, phosphates and nitrates of Ca, Mg, Sr, Fe, Al, Li, K, Na, Sn, NH 4 , and Cu and mixtures and hydrates thereof. The polymer may be present in from about 0À3 to 6À0 pounds per gallon (36-720 g/1) of the gelable composition, and preferably the composition is formed by flowing separate streams of the water-dispersible synthetic polymer and aqueous salt solution into the opening, permitting the streams to meet and mix by normal turbulence so that the composition is formed in situ prior to setting to the desired water-swellable solid. In the examples, the polymers used are sodium polystyrene sulphonate, polyvinyl pyrrolidone, polyethylene oxide, polyvinyl alcohol, polyvinyl morpholinone, a copolymer of vinyl acetate and maleic acid half amide and a copolymer of vinyl pyrrolidone maleic anhydride copolymer, and the metal salt is a chloride of zinc and/or calcium, potassium acetate or carbonate or ferric and calcium chlorides.
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