Disclosed are a method of preparing a resin powder and an integrated reactor for the same. When a coagulation process is performed using an acidic coagulant in the integrated coagulator for latex coagulation and aging according to the present invention, a remaining acidic coagulant is also removed from a reactor through neutralization, and thus, a resin powder having enhanced moist-heat resistance and thermal stability may be prepared.

A synthetic polyisoprene latex containing synthetic polyisoprene, wherein the synthetic polyisoprene constituting the synthetic polyisoprene latex includes a low-molecular weight synthetic isoprene chain having a molecular weight of less than 1,000,000 at a content rate of 10 to 70% by weight and a high-molecular weight synthetic isoprene chain having a molecular weight of 1,000,000 or more at a content rate of 30 to 90% by weight. Also, a method for producing the synthetic polyisoprene latex, wherein the synthetic polyisoprene containing the low-molecular weight synthetic isoprene chain and the high-molecular weight synthetic isoprene chain is obtained by polymerizing a monomer containing isoprene in an organic solvent by use of an organic alkali metal catalyst.

A method for producing a synthetic polyisoprene latex, including a step of mixing a latex of synthetic polyisoprene (A) synthesized by use of a Ziegler type catalyst and a latex of synthetic polyisoprene (B) synthesized by use of an organic alkali metal catalyst at a weight ratio of synthetic polyisoprene (A): synthetic polyisoprene (B)=10:90 to 90:10. In the method, preferably, the weight average molecular weight of the synthetic polyisoprene (A) is 100,000 to 3,000,000 and the weight average molecular weight of the synthetic polyisoprene (B) is 1,000,000 to 5,000,000.

A method for producing a polymer latex, includes a step of emulsifying a polymer solution of a synthetic polyisoprene and/or a styrene-isoprene-styrene block copolymer, in water in the presence of a rosin and/or a rosin metal salt, thereby obtaining an emulsified liquid, wherein the rosin and/or the rosin metal salt to be used have/has a total content rate of abietic acid, neoabietic acid and palustric acid, and salts thereof, of 5% by weight or less.

A method for producing a modified conjugated diene polymer latex, includes: a modification step of obtaining a modified conjugated diene polymer by contacting a conjugated diene polymer with a radical generator; and an emulsification step of emulsifying the modified conjugated diene polymer in water, wherein the modification step includes modifying the conjugated diene polymer on a condition where the total amount of an organic solvent and water used is 20 parts by weight or less with respect to 100 parts by weight of the conjugated diene polymer.

Methods to make a silica elastomer composite with a destabilized dispersion of silica are described, along with silica elastomer composites made from the methods. The advantages achieved with the methods are further described.

Disclosed is a dip-formed article obtained by dip-molding a latex composition for dip-forming, which contains a crosslinking agent and a latex for dip-forming containing a copolymer composed of 40-80% by weight of conjugated diene monomer units (A) containing an isoprene unit, 20-45% by weight of ethylenically unsaturated nitrile monomer units (B), and 2-15% by weight of ethylenically unsaturated acid monomer units (C), and having a weight ratio of butadiene unit content to isoprene unit content that falls within the range of 60:40 to 100:0. Tear strength is at least 50 N/mm, tensile strength is at least 25 MPa, and oil swelling rate does not exceed 5%.

A latex composition containing a conjugated diene polymer latex and a medium-chain fatty acid glyceride, wherein a content proportion of the medium-chain fatty acid glyceride is 1 to 40 parts by weight with respect to 100 parts by weight of the conjugated diene polymer. In the present invention, a medium-chain fatty acid forming the medium-chain fatty acid glyceride is preferably a fatty acid having 6 to 18 carbon atoms. In the present invention, the medium-chain fatty acid glyceride is preferably a medium-chain fatty acid triglyceride. The latex composition preferably further contains a crosslinking agent.

A method of producing a packaging structure, including the steps: coating at least one surface of a first sheet base material and/or a second sheet base material with a synthetic polyisoprene latex having a weight average molecular weight of 500,000 -5,000,000 and/or a styrene-isoprene-styrene block copolymer having a weight average molecular weight of 100,000-300,000, sandwiching an article to be packaged in a state wherein the first and second sheet base material are in contact with each other via a latex coated surface formed on the first and/or second sheet base material to thereby obtain a laminated body, pressing a portion where at least the first and second sheet base material of the laminated body are in contact with each other via the latex coated surface at a temperature of 100 C. or less to thereby obtain a pressed laminated body, and performing a sterilization treatment on the pressed laminated body.

Disclosed herein is a polymeric article comprises an elastomeric layer comprising cured synthetic polyisoprene particles that comprise a rare earth catalysed polyisoprene. The polyisoprene particles may comprise sulfur crosslinks and/or may be pre- vulcanized. Also disclosed herein are methods for producing polymeric articles comprising an elastomeric layer comprising cured synthetic polyisoprene particles that comprise a rare earth catalysed polyisoprene.