| 摘要 |
PROBLEM TO BE SOLVED: To obtain a low-dinuclear-component-content novolak phenolic resin inexpensively and relatively simply by reacting a phenol with an aldehyde in the presence of an acidic catalyst and a phosphoric ester. SOLUTION: This resin is prepared by reacting a phenol such as phenol, cresol, t-butylphenol, t-octylphenol, or xylenol with an aldehyde selected from among formalin, paraformaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, trioxane, etc., in the presence of 0.1-20 wt.%, desirably, 1-10 wt.%, based on the charge of the phenol, phosphoric ester of the formula and an acidic catalyst at a temperature equal to or lower than the reflux temperature and concentrating the reaction mixture by dehydration in a vacuum. In the formula, R1 and R2 are each a 1-10C alkyl or phenyl; and (x), (y), and (z) are in the ranges: 1<=x<=2; 0<=y<=2; and 0<=z<=2, provided that x+y+z=3.
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