| 摘要 |
<p>1,256,542. Impregnating wood. GENERAL MILLS Inc. 31 Oct., 1969 [31 Oct., 1968], No. 53587/69. Heading D1P. Wood is waterproofed by impregnation with a solution, in an inert volatile organic solvent, of an organic polyisocyanate and an imine group-containing derivative of a diisocyanate in a total concentration of 12.5-75% by weight, the equivalent ratio of NCO groups in the polyisocyanate to the imine groups in the derivative being 1.5:1 to 1:1.5. The said derivative is obtained by reaction of a compound OCN(CH 2 ) y -D-(CH 2 ) y NCO (wherein y is 0 or 1 and D is a divalent group resulting from dimerization of an ethylenically unsaturated C 16 -C 22 monocarboxylic acid) with a dialdimine or diketimine, itself being the reaction product of a polyamine containing two NH 2 groups with a compound R 1 .CO.R 2 (wherein R 1 and R 2 are H or an organic group inert to ketimine or aldimine formation, and at least one of R 1 and R 2 is such a group). The polyisocyanate may be aliphatic, aromatic or araliphatic, e.g. a tris (hexamethylene isocyanate) derivative of biuret or a compound OCN-CH 2 -D-CH 2 -NCO where D is derived from dimerized hydrogenated tall oil acids. The derivative exemplified is the reaction product of the last-mentioned diisocyanate and the diketimine prepared from diethylene triamine and methylisobutyl ketone. In examples, soft pinewood is impregnated by dipping and the wood is then air dried. Moisture in the wood and/or the air is believed to unblock the imine groups of the derivative when then react to form a polymer with the isocyanate.</p> |
