| 摘要 |
PROBLEM TO BE SOLVED: To provide a cresol novolak resin having a high molecular weight at a low cost by changing the compounding ratio of metacresol and paracresol at the initial stage and the later stage of reaction when the cresol novolak resin is manufactured. SOLUTION: Metacresol and aldehyde, or metacresol and paracresol and aldehyde are reacted (primary reaction) in the presence of an acid catalyst to obtain a cresol novolak resin low-molecular weight condensate, one kind selected from metacresol and paracresol or one kind of them and aldehyde are added to this condensate, and they are reacted (secondary reaction) to obtain an alkali-soluble cresol novolak resin component. The ratio between matecresol and paracresol is set to the range of 10/0-4/6 during the primary reaction, and it is set to the range of 8/2-2/8 during the secondary reaction. The weight-average molecular weight of the cresol novolak resin is set to 3,000 or below when the primary reaction is completed, and it is set to 3,500-20,000 for the final product. |
