PROCESS FOR REMOVING WATER
To provide a process for removing water, which is free from formation of stains due to transfer of an article among dipping sumps, with which the water removal performance will not be decreased even for an article having a complicated shape, which can suppress suspension of water in a water removal solvent in a dipping sump, and which can maintain stable water removal performance continuously for a long period of time only with one dipping sump. A process for removing water from an article, which comprises using a fluorinated solvent containing an alcohol as a water removal solvent, bringing the water removal solvent in a dipping sump to a boiling state, condensing vapor of the water removal solvent at an upper portion of the dipping sump, removing the water from the condensed water removal solvent outside the dipping sump and then returning the water removal solvent to the dipping sump, dipping an article having water attached in the water removal solvent in a boiling state in the dipping sump to remove water and then withdrawing the article.
1 . A process for removing water from an article, which comprises using a fluorinated solvent containing an alcohol as a water removal solvent, dipping an article having water attached in a liquid of the water removal solvent to dissolve or disperse the water in the water removal solvent and remove it from the article, withdrawing the article from the liquid of the water removal solvent and drying it to remove the water from the article having water attached, wherein the water removal solvent in a dipping sump in which the water removal solvent is stored is brought to a boiling state, a cooling means to condense vapor of the water removal solvent is provided at an upper portion of the dipping sump and the condensed water removal solvent is sent out of the dipping sump, a water removal solvent containing water at a concentration less than the saturated water concentration at the boiling temperature of the water removal solvent or containing no water is introduced to the dipping sump, and the article having water attached is dipped in the liquid of the water removal solvent in a boiling state in the dipping sump to remove water, and then the article is withdrawn from the liquid of the water removal solvent.
2 . The process for removing water according to claim 1 , wherein the amount of the condensed water removal solvent sent out is adjusted so that the water concentration contained in the water removal solvent boiling in the dipping sump is at most the saturated water concentration at the boiling temperature when the article is withdrawn, and the amount of the water removal solvent introduced to the dipping sump is adjusted to be substantially equal to the amount of the water removal solvent sent out.
3 . The process for removing water according to claim 1 , wherein the water removal solvent sent out of the dipping sump is introduced to a water separation sump, the water is separated from the water removal solvent in the water separation sump by a specific gravity separation method, the separated water is discharged from the water separation sump, and the water removal solvent from which the water is separated is introduced from the water separation sump to the dipping sump as the water removal solvent containing water at a concentration less than the saturated water concentration.
4 . The process for removing water according to claim 3 , wherein the temperature (T) of the water removal solvent in the water separation sump is T b −10≦T<T b (wherein T b is the boiling point of the water removal solvent).
5 . The process for removing water according to claim 1 , wherein the fluorinated solvent is a hydrofluoroether or a hydrofluorocarbon.
6 . The process for removing water according to claim 1 , wherein the fluorinated solvent is at least one hydrofluoroether selected from the group consisting of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethylether, (perfluorobutoxy)methane and (perfluorobutoxy)ethane.
7 . The process for removing water according to claim 1 , wherein the fluorinated solvent is at least one hydrofluorocarbon selected from the group consisting of 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorohexane, 1,1,1,3,3-pentafluorobutane and 1,1,1,2,2,3,4,5,5,5-decafluoropentane.
8 . The process for removing water according to claim 1 , wherein the alcohol is a C 1-3 alkanol.
9 . The process for removing water according to claim 1 , wherein the content of the alcohol in the water removal solvent is from 3 to 15 mass %.
10 . The process for removing water according to claim 1 , wherein the water removal solvent is an azeotropic composition of the alcohol and the fluorinated solvent.