| 摘要 |
The invention concerns a bottom-residue product containing isocyanate groups and with a toluylene diisocyanate content of less than 5 % by wt., preferably less than 1 % by wt., and in particular less than 200 ppm by wt.. The product is obtained from (A) distilliation residues arising in the production of toluylene diisocyanate, by mixing the distillation residues (A) with (B) polyisocyanates or polyisocyanate mixtures of the diphenylmethane series optionally modified with urethane and/or allophane groups and with an NCO content of at least 15 % by wt., followed by distillation of the mixture, the mixture being heated, before or during distillation, to temperatures of 190 to 250 DEG C, thus causing a high degreee of substitution of the toluylene diisocyanate, reversibly bound up in the distillation residues (A), by polyisocyanates (B). The product is suitable for use as a binder in the production of substrates for the manufacture of pressed products. |
