| 摘要 |
PROBLEM TO BE SOLVED: To efficiently perform a dehydration drying of a vinyl monomer at low temperatures in high operability by gas-liquid contact under reduced pressures between the liquid vinyl monomer and a mixed gas of oxygen and nitrogen with a dew point of <=0 deg.C. SOLUTION: A vinyl monomer is subjected to dehydration drying by gas- liquid contact under a reduced pressure (pref. 600 mmHg, more pref. <=500 mmHg) between the liquid vinyl monomer [a compound having a (meth)acryloyl group, also pref. liquid at normal temperatures] and a mixed gas of oxygen and nitrogen with a dew point of <=0 deg.C, pref. <=-5 deg.C, more pref. <=-10 deg.C [with a mixing volume ratio of pref. (5:95) to (90:10) under an identical pressure]. By this method, the dehydration drying can be done without the need of heating, therefore enabling a dehydration drying of a composition incorporated with a polymerization initiator such as thermal polymerization initiator or photopolymerization initiator.
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