PROCESS FOR PRODUCING POWDERY HYDROPHILIC FILLERS

摘要

1384516 Production of powdery hydrophilic polymers CESKOSLOVENSKA AKADEMIE VED 21 June 1973 [26 June 1972] 29549/73 Heading C3P A process for producing a powdery hydrophilic filler material comprises copolymerizing a monomer containing carboxylic groups or groups which can be readily converted into carboxylic groups at a concentration of 5-60 wt. per cent, with 0À1 to 40 wt. per cent (based on the monomers), of a cross-linking monomer containing more than one vinyl or vinylidene group, in a solvent or a mixture of solvents which do not dissolve the formed copolymer and from which the polymer precipitates with a particle size below 100 Ám, and then converting the polymer into the sodium potassium or ammonium salt form. Examples of the carboxylic monomer are acrylic acid, methacrylic acid, fumaric acid, maleic acid, anhydrides and acid chlorides thereof, and mixtures of the above. Examples of the cross-linking monomer are divinylbenzene, ethylene glycol dimethacrylate and diethyl glycol dimethacrylate. The conversion into the salt form may be effected directly in the polymerization solvent after polymerization, after the polymer has been isolated, or in a solvent or mixture of solvents which dissolve the monomers but not the polymer. Reagents for forming the sodium, potassium or ammonium salt may be an aqueous or alcoholic solution of the appropriate hydroxide, hydrogen carbonate or alcoholate. In the examples, the indicated monomers are polymerized in the indicated solvents and converted to salts; (1) ethylene glycol dimethacrylate (EGDM) and methacrylic or acrylic acid in toluene; (2) maleic anhydride and divinyl benzene in methyl ethyl ketone; (3) methacrylic acid maleic anhydride and divinyl benzene in cyclopentanone; (4) methacrylic acid and EGDM in propanol and (5) maleic acid and EGDM in butanol.