反应详情

The method (a) is a method wherein only water is distilled out at 50~100° C. under a reduced pressure of less than 760 mmHg, as the system is not forming azeotropic mixture with water. The method (b) is a method wherein orthocarboxylic acid esters, such as methyl orthoformate, ethyl orthoformate, methyl orthoacetate, ethyl orthoacetate or the like, or diketene, formamide, dicyclohexyl carbodiimide or the like is added and the residual water is decomposed by reacting therewith at 30~90° C. If the reaction temperature is lower than 30° C., the water decomposition will require a long time, while if in excess of 90° C., moisture will condense at vacant spaces in the reactor, rather resulting in insufficient water-removal, so that either case is not preferable. In this water removing method, low boiling point solvents are by-produced as decomposition products, such as methyl alcohol, ethyl alcohol, methyl formate, ethyl formate, methyl acetate, ethyl acetate or the like, when the orthocarboxylic acid esters are used, or such as acetone or the like, when the diketene is used. Therefore, it is preferred that these low boiling point solvents are distilled off under vacuum, after the water decomposition reaction, for the purpose of preventing popping of coating films. Further, ammonium formate when the formamide is used, or dicyclohexyl urea when dicyclohexyl carbodiimide is used, is by-produced, such a decomposition product is required to be separated by filtration after the water decomposition reaction. The method (c) is a method wherein the organic layer is passed through a column filled with polymer water absorbents, such as Sumika Gel S-50, SP-520, N-100, Np-1020, F-03, F-51 or F-75 (all trade names, manufactured by Sumitomo Chemical Co., Ltd.), Aquakeep 4S or 10HS (both trade names, manufactured by Seitetsu Kagaku Co., Ltd.) or molecular sieves, or a method wherein any one of or a mixture of the above polymer water absorbents, molecular sieves or dehydrates of inorganic salts such as sodium sulphate, calcium chloride, calcium oxide or the like is admixed with the organic layer and, after stirring, separated by filtration. The method (d) is a water removing method that has been generally used to obtain dry particles after emulsion polymerization, as is for example referred to British Patent No. 967,051, page 5, wherein organic solvents capable to form an azeotropic mixture with water are added and water is azeotropically distilled off at 50~100° C. Alternatively, it is a method wherein the organic layer is sprayed at 20~100° C. from a nozzle to vaporize water with organic solvent and then drying residue is dispersed again in the organic solvent.

1. distillationis distilled out at 50~100° C. under a reduced pressure of less than 760 mmHg, as the system
2. customis not forming azeotropic mixture with water
3. customat 30~90° C
4. customis lower than 30° C.
5. customwhile if in excess of 90° C., moisture will condense at vacant spaces in the reactor
6. customremoval