摘要:
This invention relates to an improvement in a process for producing a latex containing dispersed polymer. The improvement in the process for polymerizing a reaction mixture of vinyl monomer, stabilizer, oxidizing agent and reducing agent comprises using a water-soluble ketone bisulfite as the reducing agent, either alone or with other reducing agents, the ketone having from 3 to 8 carbon atoms in the structure. During the polymerization, the ketone bisulfite is maintained in stoichiometric excess of the oxidizing agent. Vinyl acetate-ethylene copolymers are some of the preferred polymer systems produced.
摘要:
A vinyl alcohol copolymer comprising the following general structure ##STR1## where R is hydrogen or methyl;R.sup.1 is a C.sub.6 -C.sub.18 hydrocarbyl group not containing an olefinic functionality;x is 70 to 99.5% mole %;y is 0 to 29.5 mole %; andz is 0.5 to 8 mole %.
摘要:
An extrudable polyvinyl alcohol composition useful for packaging and molding applications is prepared by melt blending polyvinyl alcohol and thermoplastic modified starch to provide a product which has reduced water sensitivity, improved modulus and reduced elongation at high relative humidity.A method for extruding the polyvinyl alcohol composition comprises:adding sufficient energy to the polyvinyl alcohol composition to both melt it and essentially eliminate the polyvinyl alcohol crystallinity in the melt, andsimultaneously removing energy from the melt at a rate sufficient to avoid decomposition of the polyvinyl alcohol.The thermoplastic modified starch may be added to the polyvinyl alcohol before or during the melting of the polyvinyl alcohol and elimination of its crystallinity, or the starch may be blended with the thus treated polyvinyl alcohol and then melt extruding the polyvinyl alcohol/starch blend.
摘要:
A vinyl alcohol copolymer comprising the following general structure: ##STR1## wherein R is hydrogen or methyl;R.sup.1 is hydrogen or methyl;R.sup.2 is hydrogen, C.sub.1 -C.sub.20 alkyl, C.sub.6 -C.sub.20 aryl or C.sub.7 -C.sub.30 alkylaryl;n is a number from 1-1,000;x is 50-99.9 mole %;y is 0-50 mole %; and z is 0.001-50 mole %.
摘要:
A solid state process for modifying polyvinyl alcohol using a Michael-type addition wherein dry polyvinyl alcohol powder is sprayed with a solution of a monomer capable of Michael-type addition in an amount sufficient to swell the polyvinyl alcohol or maintain its swollen state, but not dissolve or form a slurry of the polyvinyl alcohol. The swollen polyvinyl alcohol is sprayed with a catalyst and the temperature is raised to initiate the reaction between the polyvinyl alcohol and the monomer.
摘要:
An extrudable polyvinyl alcohol composition useful for packaging and molding applications is prepared by melt blending polyvinyl alcohol and thermoplastic polyethylene oxide to provide a product which has improved pH stability and salt solution solubility. Useful extruded articles prepared from such compositions include films and containers.A method for extruding the polyvinyl alcohol composition comprises:adding sufficient energy to the polyvinyl alcohol composition to both melt it and essentially eliminate the polyvinyl alcohol crystallinity in the melt, andsimultaneously removing energy from the melt at a rate sufficient to avoid decomposition of the polyvinyl alcohol.The thermoplastic polyethylene oxide may be added to the polyvinyl alcohol before the polyvinyl alcohol is melted and its crystallinity eliminated or blended with the thus thermally treated polyvinyl alcohol and then melt extruding the polyvinyl alcohol/polyethylene oxide blend.
摘要:
An extruable polyvinyl alcohol composition useful for packaging and molding applications is prepared by melt blending polyvinyl alcohol and thermoplastic polyurethane to provide a product which has low water absorptivity, improved impact resistance, and improved low temperature/low humidity tensile properties. Useful extruded articles prepared from such compositions include films and bottles.A method for extruding the polyvinyl alcohol composition comprises:adding sufficient energy to the polyvinyl alcohol composition to both melt it and essentially eliminate the polyvinyl alcohol crystallinity in the melt, andsimultaneously removing energy from the melt at a rate sufficient to avoid decomposition of the polyvinyl alcohol.The thermoplastic polyurethane may be added to the polyvinyl alcohol before the polyvinyl alcohol is melted and its crystallinity eliminated or blended with the thus treated polyvinyl alcohol and then melt extruding the polyvinyl alcohol/polyurethane blend.
摘要:
An aqueous size composition for cotton-containing textile yarn comprising in an aqueous solution(a) 100 parts polyvinyl alcohol(b) 2-15 parts hydrophobic waxy material(c) 0.2-5 parts ethylene oxide-propylene oxide surfactant which has a surface tension between about 37 and 48 dynes/cm as a 0.1% aqueous solution at 25.degree. C., and a foaming number less than about 20 (ml foam/g solution).degree. F. as a 7% aqueous polyvinyl alcohol solution containing 11.4 parts hydrogenated tallow wax and 2 parts surfactant per 100 parts polyvinyl alcohol.
摘要:
A substantially homogeneous random vinyl acetate copolymer comprising the following general structure: ##STR1## wherein R is hydrogen or methyl;R.sup.1 is hydrogen or methyl;R.sup.2 is hydrogen, C.sub.1 -C.sub.20 alkyl, C.sub.6 -C.sub.20 aryl or C.sub.7 -C.sub.30 alkylaryl;n is a number from 1-1,000;y is 50-99.999 mole%; andz is 0.001-50 mole%.The vinyl acetate copolymer is hydrolyzed to provide a substantially random homogeneous vinyl alcohol copolymer that can be thermoplastically processed into shaped articles possessing good gas barrier properties.
摘要:
A method is provided for reducing the solvent content and increasing the sticking temperature of polyvinyl alcohol, which is prepared from the alcoholysis of polyvinyl acetate, charged to a dryer. The polyvinyl alcohol from the alcoholysis reaction, without prior vacuum drying at an elevated temperature, is slurried in a liquid medium comprising methanol, methyl acetate, water and, optionally, a nonsolvent for polyvinyl alcohol. The slurry is heated to at least 60.degree. C. for at least 5 minutes. The polyvinyl alcohol burnt particle count is reduced in the subsequent drying step and a product is afforded which has a reduced ash content and increased cold water solubility and low temperature solubility.