| 摘要 |
A non-erasable pencil lead has its pores impregnated with an unsatd. cpd. contg. an unsatd. gp. with an I2 no. of 130 or higher, the unsatd. cpds. pref. being fatty acids, fatty acid esters, fatty acid glycerides, mixts. of natural drying oils, synthetic (opt. fractionated) drying oils, copolymerised drying oils, fatty acid esters of polyhydric alcohols, dehydrogenated (or dehydrated) castor oil or conjugated isomerised oils.
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