摘要:
Provided is a dispersion assistant useful for suspension polymerization of vinyl-based compounds. The dispersion assistant comprises a polyvinyl alcohol-based polymer (A) comprising a constituent unit represented by the general formula (1) shown below at 0.1 to 10 mol % per polyvinyl alcohol monomer unit and having a saponification degree of 15 to 70 mol %. (In the formula, R denotes an alkyl group.)
摘要:
A dispersion stabilizer for suspension polymerization is provided that includes a vinyl alcohol-based polymer (A), wherein a 0.1 mass % concentration aqueous solution of the polymer (A) has an absorbance (a1) of less than 0.25 at a wavelength of 280 nm, the aqueous solution has an absorbance (a2) of less than 0.030 at a wavelength of 320 nm, the polymer (A) has a degree of saponification of not less than 68 mol % and not more than 98 mol %, the polymer (A) has a viscosity-average degree of polymerization of more than 1500 and less than 4500, and the polymer (A) in powder form has a YI value of not less than 5. The dispersion stabilizer is capable of producing a vinyl-based resin that is excellent in polymerization stability, has a small particle size, and has an improved bulk density.
摘要:
A method for producing a polymer, which contains: bringing a monomer containing a vinyl bond into contact with a compressive fluid and melting or dissolving the monomer containing a vinyl bond, followed by carrying out addition polymerization of the monomer containing a vinyl bond in the presence of an initiator.
摘要:
Water-redispersible polymer powder compositions are obtained by means of free-radical-initiated polymerization in aqueous medium of one or more monomers of vinyl esters of unbranched or branched alkylcarboxylic acids having from 1 to 15 carbon atoms, methacrylic esters and acrylic esters of alcohols having from 1 to 15 carbon atoms, vinylaromatics, olefins, dienes and vinyl halides and subsequent drying of the polymer dispersion, wherein one or more silanes of the general formula (RO)3−nR1nSiR2X (1) where X is an amino- or epoxy-containing radical are added before drying of the polymer dispersion. The powders are especially useful in tile adhesives for tiles having low water absorbtion capacity.
摘要:
Acetic acid is converted to vinyl acetate monomer by a reaction with oxygen and ethylene. The vinyl acetate is polymerized to form a vinyl acetate polymer or copolymer, which is then reacted in a methanolysis reaction with methanol and base to form a polymer or copolymer of vinyl alcohol and a methyl acetate byproduct. Ethanol is produced from methyl acetate by a hydrogenolysis reaction. The hydrogenolysis reaction also produces methanol. At least a portion of this ethanol is converted to ethylene by a dehydration reaction. At least a portion of the ethylene produced in this dehydration reaction is recycled to react with acetic acid and oxygen to form vinyl acetate. By converting a byproduct and by recycle of compositions, a polymer or copolymer of vinyl alcohol is efficiently produced with minimal waste.
摘要:
Ethanol is produced from methyl acetate by a hydrogenolysis reaction. The methyl acetate is produced as a byproduct during the conversion of a vinyl acetate polymer or copolymer to a polymer or copolymer of vinyl alcohol. By integrating the two processes, a valuable product, i.e. ethanol, is produced from a methyl acetate byproduct.
摘要:
The invention relates to a process for producing formulations of sparingly water-soluble substances, said sparingly soluble substances being present in amorphous embedded form in a copolymer, and said copolymer being obtained by free-radically initiated polymerization of a mixture of i) 30 to 80% by weight of N-vinyllactam, ii) 10 to 50% by weight of vinyl acetate, and iii) 10 to 50% by weight of a polyether, with the proviso that the sum of components i), ii) and iii) equals 100% by weight, which comprises embedding the sparingly soluble substance into the copolymer at temperatures above the melting point of the sparingly soluble substances.
摘要:
Solid polyvinyl acetate resins functionalized by acid groups which also contain terminal carboxy groups besides carboxy-functional comonomer units display superior properties as low profile additives for unsaturated polyester resins.
摘要:
For preparing a water-containing vinyl acetate polymer dispersion, vinyl acetate monomer and initiator are added to a water solution from an emulsifier and hydroxypropyl starch and/or hydroxyethyl starch. The emulsifier amount is equal to 0,5 to 5 weight % from the monomer amount. The degree of substitution of the starch is higher than 0,8 substituted glucose hydroxyl groups per anhydroglucose unit and lies more specially between 0,8 and 1,8 substituted glucose hydroxyl groups per anhydroglucose unit, when the starch is hydroxypropyl starch or between 0,8 and 2,75 substituted glucose hydroxyl groups per anhydroglucose unit, when the starch is hydroxyethyl starch.
摘要:
Telomers useful for stabilizing aqueous formaldehyde solutions are made by telomerising vinyl acetate and carbon tetrachloride, oxidising the product, and then acetalising it with formaldehyde.