| 摘要 |
A method for the prodn. of a resin which is used for mfg. an adhesive for cellulose based prods., comprises mixing (i) 30-70 wt.% of a urea phenol resin (I); with (ii) 70-30 wt.% of a melamine resin (II). (I) is obtd. either by (1) adding to a precondensate of formaldehyde, urea and opt. melamine, a crosslinking agent contg. a co-condensate of phenol, formaldehyde and urea, or contg. also a co-condensate of phenol and formaldehyde as urea; condensing under acid conditions; stopping the reaction by alkalisation; and adding additional urea to adjust the final molar ratio to 1.4-0.6 moles of urea, 0.006-0.3 moles of phenol and 0-0.04 moles of melamine/mole of formaldehyde; or by (2) adding to an evaporated condensate of formaldehyde, urea and opt. melamine, a crosslinking agent as specified above, so that the final molar ratio is as specified previously in (1). (II) is obtd. by condensing melamine and formaldehyde in a molar ratio of formaldehyde to melamine of 1.7-2.4. |
