Water absorbent polymers and a process for their preparation are disclosed. The process for preparing water absorbent polymers comprises preparing a slurry with relatively high amounts of polymer particles (in the range of 40 to 55 wt % of the total mass of the slurry) having water absorbed therein. The slurry is then directly spray dried to obtain water absorbent polymers.

[Problem to be Solved]

Provided are an aqueous dispersion of a fluoroolefin and the like that do not corrode vessels and enable a copolymer to be given at a high conversion ratio and high productivity from the fluoroolefin as a raw material monomer.

[Solution]

An aqueous dispersion containing: a fluoroolefin (a) represented by the following general formula (1); a surfactant (c) represented by the following general formula (2); and a dispersion medium containing water, wherein the aqueous dispersion has a cumulant diameter of 250 to 2,000 nm, and the aqueous dispersion has a pH of 2.0 to 7.0:

CF.sub.2═CF—[O—CF.sub.2—CF(CF.sub.3)].sub.n—O—[CF.sub.2].sub.m—Z   (1) wherein n represents an integer of 0 or more and 2 or less, m represents an integer of 2 or more and 4 or less, and Z represents CF.sub.3, SO.sub.2F, or COOH.sub.3, and

CF.sub.3—[CF.sub.2].sub.m—O—[CF(CF.sub.3)—CF.sub.2—O].sub.n—CF(CF.sub.3)—Z   (2) wherein m represents an integer of 0 to 2, n represents an integer of 0 to 6, Z represents COOM, wherein N represents H, Li, Na, K, or NR.sub.4, wherein R represents H or a linear alkyl group having 1 to 4 carbon atoms.

[Problem to be Solved]

Provided are an aqueous dispersion of a fluoroolefin and the like that do not corrode vessels and enable a copolymer to be given at a high conversion ratio and high productivity from the fluoroolefin as a raw material monomer.

[Solution]

An aqueous dispersion containing: a fluoroolefin (a) represented by the following general formula (1); a surfactant (c) represented by the following general formula (2); and a dispersion medium containing water, wherein the aqueous dispersion has a cumulant diameter of 250 to 2,000 nm, and the aqueous dispersion has a pH of 2.0 to 7.0:

CF.sub.2═CF—[O—CF.sub.2—CF(CF.sub.3)].sub.n—O—[CF.sub.2].sub.m—Z   (1) wherein n represents an integer of 0 or more and 2 or less, m represents an integer of 2 or more and 4 or less, and Z represents CF.sub.3, SO.sub.2F, or COOH.sub.3, and

CF.sub.3—[CF.sub.2].sub.m—O—[CF(CF.sub.3)—CF.sub.2—O].sub.n—CF(CF.sub.3)—Z   (2) wherein m represents an integer of 0 to 2, n represents an integer of 0 to 6, Z represents COOM, wherein N represents H, Li, Na, K, or NR.sub.4, wherein R represents H or a linear alkyl group having 1 to 4 carbon atoms.

A method for recovering an unreacted α,β-ethylenically unsaturated nitrile monomer contained in a latex of a nitrile rubber obtained by emulsion polymerizing a monomer mixture comprising an α,β-ethylenically unsaturated nitrile monomer and a carboxyl group-containing monomer is provided. The method includes the steps of: adjusting a pH of the latex of the carboxyl group-containing nitrile rubber to 6.5 or more; decompressing the latex of the carboxyl group-containing nitrile rubber having the pH adjusted to 6.5 or more under a heating condition; and recovering a component evaporated by the decompression under the heating condition.

A method for recovering an unreacted α,β-ethylenically unsaturated nitrile monomer contained in a latex of a nitrile rubber obtained by emulsion polymerizing a monomer mixture comprising an α,β-ethylenically unsaturated nitrile monomer and a carboxyl group-containing monomer is provided. The method includes the steps of: adjusting a pH of the latex of the carboxyl group-containing nitrile rubber to 6.5 or more; decompressing the latex of the carboxyl group-containing nitrile rubber having the pH adjusted to 6.5 or more under a heating condition; and recovering a component evaporated by the decompression under the heating condition.

Water-redispersible polymer powders with improved characteristics in building materials are prepared using a drying aid which is a polyvinyl alcohol copolymer also containing vinyl ester monomers and specific comonomers.

Water-redispersible polymer powders with improved characteristics in building materials are prepared using a drying aid which is a polyvinyl alcohol copolymer also containing vinyl ester monomers and specific comonomers.

The present invention relates to a method of preparing a thermoplastic resin, a thermoplastic resin prepared by the same, and a thermoplastic resin composition including the same. More specifically, the method of the present invention includes a step of performing acid coagulation of emulsion polymerization latex, a step of treating coagulated slurry with a base and performing dehydration, and a step of adding a metal salt and water to dehydrated wet powder to adjust pH to 9 or more. According to the present invention, the method may increase the productivity of a thermoplastic resin, and the thermoplastic resin prepared by the method has excellent mechanical strength, thermal stability, and appearance properties. In addition, when the thermoplastic resin of the present invention is used in coating, the thermoplastic resin has an effect of improving the adhesive strength and appearance quality of a coating film.

The present invention relates to a method of preparing a thermoplastic resin, a thermoplastic resin prepared by the same, and a thermoplastic resin composition including the same. More specifically, the method of the present invention includes a step of performing acid coagulation of emulsion polymerization latex, a step of treating coagulated slurry with a base and performing dehydration, and a step of adding a metal salt and water to dehydrated wet powder to adjust pH to 9 or more. According to the present invention, the method may increase the productivity of a thermoplastic resin, and the thermoplastic resin prepared by the method has excellent mechanical strength, thermal stability, and appearance properties. In addition, when the thermoplastic resin of the present invention is used in coating, the thermoplastic resin has an effect of improving the adhesive strength and appearance quality of a coating film.

A process for producing superabsorbents, comprising polymerization of a monomer solution and thermal surface postcrosslinking, wherein the monomer solution comprises at least 0.75% by weight of a hydroxyphosphonic acid or salts thereof, calculated on the basis of the total amount of monomer used, and at least 0.09% by weight of aluminum cations, calculated on the basis of the total amount of polymer particles used, is added to the polymer particles before, during or after the thermal surface postcrosslinking.