Patent ID: 8519083

Claim:
A process for producing an MEK-modified resorcinol-formalin resin, the process comprising: (a) mixing, in any order, and dissolving: 100 parts by mass of water; 20 to 40 parts by mass of resorcinol (A), relative to the 100 parts by mass of the water; and 20 to 80 parts by mass of calcium chloride (B), relative to the 100 parts by mass of the water; then (b) adding, in any order: 10 to 100 parts by mass of methyl ethyl ketone (C), relative to 100 parts by mass of the resorcinol (A), followed by stirring to form a two-phase mixture which does not contain residual solid content; and hydrochloric acid (D) as a catalyst; then (c) adding dropwise 1 to 40% formalin (E) under stirring in such an amount that results in a formaldehyde/resorcinol molar ratio of 0.3 to 0.7, thereby allowing a liquid-liquid heterogeneous mixture to react; then (d) allowing the liquid-liquid heterogeneous mixture to stand and separate into two layers, and then removing an aqueous layer ( 0 ); then (e) adding water to a methyl ethyl ketone layer ( 0 ), which is a reaction product layer that remains after removing the aqueous layer ( 0 ), in an amount of from an equivalent amount to 5 times the amount of the reaction product layer, to conduct a water washing; then (f) allowing a resulting mixture ( 1 ) to stand and separate into two layers, and then removing an aqueous layer ( 1 ), thereby obtaining a methyl ethyl ketone layer ( 1 ); then (g) further conducting at least one additional water washing of the methyl ethyl ketone layer ( 1 ) to remove an aqueous layer ( 2 ), thereby obtaining a methyl ethyl ketone layer ( 2 ) comprising an MEK-modified resorcinol-formalin resin; then (h) adding water in an amount of from 2.5 to 5 times by mass to the methyl ethyl ketone layer ( 2 ), and then adding 1 to 30% aqueous ammonia to form a resulting mixture ( 2 ) comprising an aqueous resin solution ( 1 ); and then (i) distilling the resulting mixture ( 2 ), thereby removing the methyl ethyl ketone (C), to obtain an aqueous resin solution ( 2 ) having: an MEK-modified resorcinol-formalin resin concentration of from 30 to 80%; moderate flowability with a pH of 6 to 10; a calcium chloride (B) concentration of 100 ppm or less; a peak area corresponding to a resorcinol monomer of from 3 to 9% to an entire peak area obtained by gel permeation chromatography analysis; and a peak area corresponding to resorcinol pentanuclear or higher nuclear bodies of from 30 to 55% to the entire peak, wherein recovery and reuse of specific raw materials comprising water, the calcium chloride (B), and the methyl ethyl ketone (C), in the production steps, and recovery and reuse of methanol contained in the formalin (E), are carried out in parallel.