vegetable tanning extract是什么意思

用法例句

It was discovered that corrosion resistance of the epoxy antirust paint could be improved and rust could be conversed by adding vegetable tannic acid in the paint.

通过实验发现在环氧－聚酰胺防锈漆中加入植物丹宁酸能提高其耐蚀性，并能够转化锈，而合成丹宁酸这种作用不明显。