PURPOSE: To obtain glass fibers having superior strength and suitable for reinforced plastics or the like by removing greige goods used to treat the surfaces of glass fibers from the fibers with starch digestive enzyme and by treating the fibers with a coupling agent.
CONSTITUTION: The surfaces of glass fibers for reinforced plastics or the like are treated with starch paste-base greige goods mixed optionally with synthetic paste such as PVA or polyvinyl acetate. The surface treated fibers are immersed in an aq. soln. contg. ≥0.005% starch digestive enzyme such as α-amylase for ≤30min. The aq. soln. is prepd. by dissolving the enzyme in water of 4.0W10.5pH having 0.001W0.1 molar concn. of Ca2+ at 0W70°C. The fibers are taken out of the aq. soln. and put in hot water at ≥80°C to deactivate the enzyme, the synthetic paste is removed by washing with an org. solvent and the greige goods are removed under flowing water. The fibers are then impregnated with a soln. contg. 0.1W3% coupling agent such as a silane, titanate or zirconium type coupling agent and drying is carried out at 60W120°C for 10W20min.
ODAJIMA TOSHIHIRO
KISHI SATOSHI
