There is provided a method for more easily producing an acrylic rubber capable of providing a crosslinked rubber having excellent water resistance. A method for producing an acrylic rubber comprising the steps of subjecting a monomer to emulsion polymerization to obtain a polymerized emulsion; mixing the polymerized emulsion with a coagulant to obtain a water-containing crumb; and water-washing the water-containing crumb, wherein, in the step of water-washing the water-containing crumb, the water-containing crumb is water-washed until an electrical conductivity of the washing water after water-washing the water-containing crumb becomes 6.0 mS/cm or less.

The present invention provides an acrylic copolymer coagulant which is a copolymer of a monomer mixture comprising a carboxylic acid-based monomer and an acrylic monomer, and a method of preparing a graft copolymer using the same. According to the present invention, a graft copolymer excellent in impact strength, surface gloss characteristics, and processability can be prepared.

The present invention provides an acrylic copolymer coagulant which is a copolymer of a monomer mixture comprising a carboxylic acid-based monomer and an acrylic monomer, and a method of preparing a graft copolymer using the same. According to the present invention, a graft copolymer excellent in impact strength, surface gloss characteristics, and processability can be prepared.

Provided is a method of preparing a graft polymer, which includes: polymerizing a monomer mixture comprising a carboxylic acid monomer and methyl acrylate, wherein the carboxylic acid monomer is included at 1.5 to 2.5 wt %, and thus preparing an acrylic coagulant having an average particle diameter of 60 to 70 nm; polymerizing diene-based monomers in the presence of an emulsifier containing a salt of a compound and thus preparing a first diene-based rubber polymer; enlarging the first diene-based rubber polymer using the acrylic coagulant and thus preparing a second diene-based rubber polymer; and graft-polymerizing an aromatic vinyl-based monomer and a vinyl cyanide-based monomer to the second diene-based rubber polymer and thus preparing a graft polymer.

The present invention relates to a method of preparing a thermoplastic resin. More particularly, the present invention relates to a method of preparing a thermoplastic resin, the method including A) a step of coagulating an emulsion-polymerized latex with an acid; B) a step of treating the coagulated aggregate (slurry) with a base, followed by dehydration; and C) a step of treating the dehydrated wet powder with an acid, followed by dehydration. A method of preparing a thermoplastic resin which exhibits reduced gas generation, color improvement, and superior thermal stability is provided.

A masterbatch manufacturing method in accordance with the present disclosure comprises an operation in which pre-coagulation rubber latex comprising filler is coagulated to obtain a coagulum; an operation in which the coagulum is dewatered; and an operation in which the dewatered coagulum is plasticized as it is dried by means of an extruder; wherein, during the operation in which the dewatered coagulum is plasticized as it is dried, the coagulum comprises a peptizing agent.

A masterbatch manufacturing method in accordance with the present disclosure comprises an operation in which pre-coagulation rubber latex comprising filler is coagulated to obtain a coagulum; an operation in which the coagulum is dewatered; and an operation in which the dewatered coagulum is plasticized as it is dried by means of an extruder; wherein, during the operation in which the dewatered coagulum is plasticized as it is dried, the coagulum comprises a peptizing agent.

A method for producing a carboxyl group-containing liquid nitrile rubber includes: bringing a latex of a carboxyl group-containing liquid nitrile rubber into contact with a mono- or divalent metal salt under a condition at a pH of 5 or less to salt out and separate the carboxyl group-containing liquid nitrile rubber from an aqueous phase.

A latex including: a nitrile rubber containing an α,β-ethylenically unsaturated nitrile monomer unit in a content of 8 to 50 wt % and an α,β-ethylenically unsaturated dicarboxylic acid monoester monomer unit in a content of 1 to 10 wt %, and having an iodine value of 120 g/100 g or less; and a benzisothiazoline-based compound represented by the following general formula (1), wherein the content of the benzisothiazoline-based compound is 50 ppm by weight or more, with respect to the nitrile rubber, and a redox potential of the latex is 80 to 800 mV. ##STR00001##
In the general formula (1) mentioned above, R.sup.1 represents a hydrogen atom, or a substituted or unsubstituted organic group, R.sup.2 each independently represents a hydrogen atom, or a substituted or unsubstituted organic group, and “n” represents an integer of 0 to 4.

The present invention relates to a solidification process of the natural rubber latex by means of polyquaternary polymers.

The process of the present invention has the advantage to not require the addition of acids and/or salts, with an evident saving in terms of cost for the reagents. Furthermore, in such a way neither the neutralization step of the rubber nor the treatment of the processing water before their disposal are required.

The process of the present invention is suitable both for the continuous and batchwise embodiment, with evident advantages as far as its industrial application is concerned.