To obtain a moisture absorbent polyester fiber product having a good resistance to washing by converting the acid terminals of unsaturated organic acids introduced into a polyester fiber product by graft polymerization to their alkali metal salts.
This product is obtained by preparing a polymerization bath of a water-based emulsion comprising 0.01 to 5 wt.% of hydrophobic free-radical initiator e.g. benzoyl peroxide, 0.01 to 2.0 wt.% of phthalimide-based compound e.g. N-alkyl phthalimide, and 0.5 to 10 wt.% of ethylenic unsaturated organic acid e.g. (meth)acrylic acid, by immersing a polyester fiber product in the polymerization bath, by graft polymerizing it by heat treatment and by treating it with a water solution comprising a basic alkali metal compound e.g. NaOH and sequestering agent e.g. ethylenediaminetetraacetic acid sodium salt. The thus obtained product has a coefficient of moisture absorption (20°C×65%RH) of ≥4% and the same of ≥3% after a repeating washing test (JISL 0217-103 method) comprising 10 washings.
ISHIDA SEIJI
OCHI SEIICHI
