| 摘要 |
FIELD: chemical technology. ^ SUBSTANCE: invention relates to producing urea-formaldehyde resins. Invention describes a method for preparing urea-formaldehyde resins involving condensation of urea-formaldehyde concentrate with carbamide. Condensation is carried out at the initial mole ratio formaldehyde to carbamide = (1.72-2.3):1 at temperature 80-95°C and medium pH 6-9 followed by change of pH medium to 3.5-5.5 with adduct based on a mixture of aliphatic aminoalcohols with inorganic and/or organic acids or their anhydrides no containing chloride ions or a mixture of aliphatic and heterocyclic aminoalcohols with inorganic and/or organic acids or their anhydrides no containing chloride ions, at their mass ratio = (1.0-3.0):1.0 in the amount 0.1-3.0% of urea-formaldehyde concentrate mass followed by carrying out the condensation reaction with additional amount of carbamide to achievement of viscosity value 30-80 s and the following condensation of additional amount of carbamide wherein the final mole ratio of formaldehyde to carbamide = (0.9-1.76):1 and cooling the resin. Invention provides the development of operated technology for synthesis of urea-formaldehyde resins with required properties and, first of all, the low content of formaldehyde after their hardening. Invention can be used in manufacturing urea-formaldehyde resins used as binding agents for making splint-slab and wood-fiber slabs, veneer, adhesives for gluing wood, binding agent components used in making heat-insulating materials and others. ^ EFFECT: improved method of synthesis of resins. ^ 3 tbl, 1 dwg, 12 ex |
