METHOD OF PRODUCING UREA-FORMALDEHYDE RESIN FOR REINFORCEMENT OF GROUND Russian patent published in 2006 - IPC C08G12/12 

FIELD: polymer production.

SUBSTANCE: preparation of urea-formaldehyde resin comprises urea/formaldehyde condensation carried out in presence of ammonia at pH varying from 7.1-7.15 to 5.1-5.3 at 88-104°C, atmosphere pressure, and urea/formaldehyde/ammonia molar ratio 1:(2.0-2.2):(0.1-0.13) until viscosity (using viscosimeter VS-4) achieves 15.5-26.0 s, after which mixture is subjected to post-condensation at 77-58°C with additional urea to achieve final urea-to-formaldehyde molar ratio 1:(1.9-2.0). Reaction mixture is the given additional amount of ammonia and held at 62-38°C for 20-30 min until final urea-to-ammonia ratio 1:(0.11-0.19).

EFFECT: enabled production of low-toxicity, freely flowing binder capable of being hardened at ambient temperature for required hardening time and providing high strength to reinforced ground, reduced production expenses, and simplified equipment.

3 cl, 1 tbl, 4 ex