Patent ID: 7834124

Claim:
A ketone-modified resorcinol-formalin resin, which is a resin (G) obtained by a process comprising: adding and dissolving, into a water solvent, resorcinol (A) in an amount of 100 to 200 parts by weight relative to 100 parts by weight of water, adding an organic acid or inorganic acid (B1) as a catalyst in an amount of 0.2 to 0.6 part by weight relative to 100 parts by weight of water, adding 1 to 40% formalin (C) dropwise in a molar ratio relative to resorcinol (A) in terms of formaldehyde/resorcinol of 0.3 to 0.8 under stirring over a period of 1 to 300 minutes while maintaining the reaction system at 0 to 150° C., stirring the aqueous resorcinol formaldehyde reaction mixture for further 20 to 90 minutes after the completion of the dropwise addition of formalin to cause a reaction to proceed, cooling the mixture after the further stirring, neutralizing the cooled mixture with adding 1 to 30% ammonia water (D1) in an amount of 1.0 to 2.0 molar equivalents relative to the organic acid or inorganic acid (B1), extracting the neutralized solution with an extracting solvent (E) in an amount of 1 to 5 equivalents relative to resorcinol (A), repeating the extraction N times, subjecting the remaining aqueous layer to azeotropic distillation to remove residual extracting solvent (E), cooling the residue obtained after the azeotropic distillation to obtain a resorcinol-formalin condensation liquid (F), adding 10 to 80 parts by weight of a liquid ketone (H) represented by the general formula [1] and 0.1 to 1.5 parts by weight of an organic or inorganic acid (B2) as a catalyst to 100 parts by weight of the condensation liquid (F), elevating the temperature to 50 to 100° C., and continuing reaction for 5 to 24 hours while maintaining the temperature, adding 10 to 50 parts by weight of water to 100 parts by weight of the reaction solution after the completion of the reaction, removing by azeotropic distillation the unreacted liquid ketone (H) and water in an amount to be removed by the azeotropic distillation, taking out the remaining water layer part, and neutralizing the remaining water mixture with 1 to 30% ammonia water (D2), to obtain the resin (G), wherein N represents an integer of 2 to 5, a peak area corresponding to resorcinol monomer is 3 to 9% and a peak area corresponding to resorcinol pentanuclear and higher nuclear bodies is 30 to 55% relative to the total peak area obtained by gel permeation chromatographic analysis of the resin (G): wherein R1 and R2 are the same or different from each other and each represents a methyl group, an ethyl group, an n-propyl group, a 2-propyl group, an n-butyl group, a secondary-butyl group, an isobutyl group, or a tertiary-butyl group.