Sanyo Chemical Industries, Ltd.

Hiroki Hagihara

Hiroki Hashimoto

Hiroki Yamashita

Ayumu Sakaguchi

Kenyuu Yoshida

Nobuhiro Naito

The present invention aims to provide a viscosity index improver composition capable of providing a lubricant composition that has an excellent viscosity index improving effect, excellent antifoaming properties, and excellent persistence of the antifoaming properties. The present invention relates to a viscosity index improver composition, containing: a (co)polymer (A) containing a monomer (a) represented by the following formula (1) as an essential monomer; a C18-C40 chain aliphatic alcohol (B); and a base oil, [Chem. 1] wherein Ris a hydrogen atom or a methyl group; —X— is a group represented by —O— or —NH—; Ris a C2-C4 alkylene group; Rand Rare each independently a C8-C24 linear or branched alkyl group; and p is an integer of 0 to 20, with each Rbeing optionally the same as or different from each other when p is 2 or greater.

Viscosity index improver composition and lubricating oil composition

A viscosity index improver containing a copolymer (A) whose essential constituent monomer is a monomer (a) having a number average molecular weight of 800 to 4,000 represented by the following formula (1), the copolymer (A) having a solubility parameter in the range of 9.00 to 9.40: wherein Ris a hydrogen atom or a methyl group; &#x2014;X&#x2014; is a group represented by &#x2014;O&#x2014;, &#x2014;O(AO)&#x2014;, or &#x2014;NH&#x2014;, AO is a C2-C4 alkyleneoxy group, m is an integer of 1 to 10, each AO may be the same or different when m is 2 or more, and the (AO)moieties may be randomly bonded or block-bonded; Ris a residue after removal of one hydrogen atom from a hydrocarbon polymer whose essential constituent monomer is butadiene in which the butadiene is present in a proportion of 50% by weight or more based on the weight of R, or after removal of one hydrogen atom from a polymer formed by partial hydrogenation of the hydrocarbon polymer; and p represents a number of 0 or 1.

Growing community of inventors

Kyoto, Japan

Hiroki Hagihara