| 摘要 |
905,061. Treating wood; proofing against fire and fungi. KOPPERS CO. Inc. March 26, 1959 [April 1, 1958], No. 10658/59. Drawings to Specification. Class 140. The resistance of wood to fire, fungi and dimensional change is increased without loss of impact strength by impregnation with an aqueous solution containing between 10 and 25% by combined weight of dicyandiamide and ortho-phosphoric acid in a mol. ratio of from 1: 1 to 3 : 1, and heating to a final temperature between 70 and 100‹ C. The aqueous solution may be pre-reacted (to form guanylurea phosphate) at a temperature of 80-100‹ C. before the impregnation. It is stated that such prereacted solutions give better retention in the wood than do solutions of preformed guanylurea phosphate. Both the pre-reacted solutions and the unreacted solutions react with the cellulose of the wood during the curing step. The solution may also contain chromated copper arsenate, chromated zinc arsenate, or chromated zinc chloride. The wood may be impregnated by applying first vacuum and then pressure while it is immersed in the solution, or by other standard processes. Specification 649,642 is referred to.
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