| 摘要 |
PROBLEM TO BE SOLVED: To produce a polyamide copolymer having high whiteness sufficient to be used in the cosmetic field, since the fine particles of polyamide produced by the conventional process is colored in yellow. SOLUTION: Since crude polyamide copolymer fine particles synthesized by the existing process are contaminated with the reaction solvent, by-products and the like and they must be removed. Thus, the nylon cake is treated with an aqueous solution containing 15-25 wt.%, based on the nylon cake, of 35% concentration of hydrogen peroxide solution at 70-75 deg.C for 20-25 minutes to give the objective polyamide of high whiteness.
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