Sanyo Chemical Industries, Ltd.

Kouzou Sakai

Shigeyuki Yoshida

Hidehiko Matsuya

Yoshihisa Ohta

Tatsuya Ohsumi

Yoshio Kano

Makoto Dakurige

A viscosity index improver, comprising an oil-soluble copolymer (A) having 20-70% by weight of alkyl acrylate units and 30-80% by weight of alkyl methacrylate units, and a viscosity index improver, comprising 20-80% by weight of an oil-soluble alkyl acrylate (co)polymer (A1) and 20-80% by weight of an oil-soluble methacrylate (co)polymer (A2), are capable of reducing high-temperature high-shear viscosity, particularly isoparaffin-containing high viscosity index oil, and provide luburicating oils useful as engine oil, gear lubricant and so on.

Lubricating oil compositions of reduced high-temperature high-shear

Viscosity index improver and lubricating oil

A viscosity index improver which contains a polymer dispersion comprising: a polyolefin having a weight average molecular weight of 10,000 to 500,000, a dispersant comprising a reaction product of an ethylenically unsaturated dicarboxylic acid added polyolefin with a carboxylic acid-reactive compound selected from the group consisting of an amine, a ketimine compound, an alcohol and an isocyanate compound and an organic liquid medium comprising a liquid phenolic derivative selected from the group consisiting of an alkyl phenol and an alkyl salicylate.

Viscosity index improver

Disclosed is a viscosity index improver in the form of a high-concentration non-aqueous dispersion of a low-viscosity olefinic polymer and a method of preparing the same. The improver comprises (1) an olefinic polymer, (2) a compound of (i) or (ii), (i) being a compound having at least one segment comprising A and B wherein A is a residue of a compound substantially composed of a hydrocarbon having a weight average molecular weight of 500 to 500,000 and having hydroxyl and/or carboxyl and/or carbonyl and/or amino and/or dithiocarboxyl group(s) and B is a residue of a compound having carboxyl and/or hydroxyl and/or isocyanate and/or amino and/or ketomine group(s), said A and B being bonded through at least one linkage selected from ester linkage, thioester linkage, urethane linkage, urea linkage, amide linkage, imide linkage and ether linkage, and (ii) being a reaction product of AA and BB wherein AA is an olefinic polymer having a weight average molecular weight of 500 to 500,000 and added with ethylenic unsaturated dicarboxylic acid(s) and BB is a compound having at least one group selected from mercapto group, amino group, ketimine group, hydroxy group and isocyanate group, said AA and BB being bonded through at least one linkage selected from thioester linkage, amide linkage, imide linkage and ester linkage, and (3) a medium which does not substantially dissolve or which scarcely dissolves the said olefinic polymer.

Viscosity index improver and method for producing the same

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Omihachiman, Japan

Kouzou Sakai