浅色松香树脂的制备及浅色机理初探

PREPARATION OF LIGHT-COLORED ROSIN ESTER AND STUDIES ON MECHANISM OF COLOR-LIGHTENING

松香在新型催化剂(CLC)存在下与醇发生酯化反应,生成加纳色号2～4的浅色松香树脂。对反应前后松香成分分析发现:加入CLC反应后松香中的脱氢枞酸和氢化树脂酸含量从零增加到30%和22%,枞酸型树脂酸含量从86%下降到34%。不加CLC的对照实验中,没有脱氢枞酸和氢化树脂酸生成,枞酸型树脂酸含量变化不大。实验表明CLC在松香酯化反应过程中起了松香歧化反应的催化作用。由于歧化反应,使松香中枞酸型树脂酸含量降低是松香浅色的主要原因。

Lightcolored rosin ester with Gardner color 2-4 was prepared by reacting rosin with alcohol in the presence of a new CLC catalyst.Analysis of the product showed that relative content of dehydroabietic acid and hydrogenated resin acids increased from 0 in rosin to 30% and 22% in rosin ester,respectively,and relative content of abietictype resin acids decreased from 86% to 34%.Contrast experiment without CLC showed that there were no products of dehydroabietic acid and hydrogenated resin acid in rosin ester,and relative content of abietictype resin acid did not change much.It was proved that CLC was a catalyst responsible for the disproportionation reaction of rosin.The decrease of abietictype resin acids through disproportionation was responsible for the colorlightening effect on rosin ester.