| 摘要 |
Solid finely divided curing catalysts for amino resins consist of (a) 20-50 wt. % of an ammonium salt of a strong mineral acid, (b) 0-50 wt. % of a retarder and (c) 1-20 % esp. 2-10 wt. % of an alkali metal or ammonium salt of an amphoteric oxide of a gp. III, IV or V metal. The compsn. may also contain known inert mineral or organic fillers. Typical components (c) are stannates, arsenates, germanates, antimonates, pyroantimonates and (esp) aluminates of sodium, potassium or ammonium. The hardeners are esp. useful for use with urea-formaldehyde adhesives in hot-cure plywood, or wood-paper laminates and give higher bond strengths with such porous substrates than known hardeners. |
