| 摘要 |
1527451 Modified phenol-formaldehyde precondensates TH GOLDSCHMIDT AG 11 Jan 1977 [12 Jan 1976] 980/77 Heading C3R [Also in Divisions E1 and B5] A method of modifying a phenol-formaldehyde precondensate comprises incorporating in the precondensate a compound of the general formula generally in an amount of from 3-20% wt., based on the weight of precondensate solids, wherein R is an aliphatic or cycloaliphatic radical having 4-6 carbon atoms or a phenyl radical and x is 1 to 2. Preferably R is butyl isobutyl, cyclohexyl or phenyl. The modifying agent can be added at any stage of the manufacture of the precondensate, e.g. at the beginning of the reaction or to the finished precondensate. The modifying agent is cocondensed into the resin upon curing. In the examples an aqueous solution of an alkaline-condensed phenol-formaldehyde precondensate is modified with (1) a mixture of C 6 H 5 OCH 2 CH 2 OH and C 6 H 5 (OCH 2 CH 2 ) 2 OH; or (2) C 4 H 9 OCH 2 CH 2 OH alone or together with C 4 H 9 (OCH 2 CH 2 ) 2 OH. Uses.-The modified precondensates can be used in the manufacture of shuttering for concrete by impregnating and coating a carrier, e.g. a paper, with an aqueous solution of the modified precondensate and then heat-pressing the coated carrier onto a substrate, e.g. a woodbased material. |
