Sanyo Chemical Industries, Ltd.

Kenyuu Yoshida

Satoshi Matsumoto

Hiroki Yamashita

Nobuhiro Naito

Shigekuni Nakada

Ayumu Sakaguchi

Hiroki Hagihara

Ryota Sato

Masahiro Hashimoto

The present invention aims to provide a viscosity-index improving agent having an excellent friction reduction effect to reduce friction of a lubricating oil composition when the viscosity-index improving agent is added thereto. The present also aims to provide a lubricating oil composition containing the viscosity-index improving agent. The present invention relates to, for example, a viscosity-index improving agent containing: (co)polymer (A) containing, as an essential constituent monomer, a polyolefin-based monomer (a) represented by the following formula (1); an ester oil (B1) having a kinematic viscosity at 100° C. of 1.00 to 2.50 mm/s; and an ester oil (B2) having a kinematic viscosity at 100° C. of 2.51 to 5.00 mm/s: wherein Ris a hydrogen atom or a methyl group; —X— is a group represented by —O—, —O(AO)-, or —NH—, A is a C2-C4 alkylene group, m is an integer of 1 to 10, and each A may be the same or different when m is 2 or more; Ris a residue after removal of one hydrogen atom from a hydrocarbon polymer containing a 1,2-butylene group as a structural unit; and p represents a number of 0 or 1.

Viscosity index improver and lubricating oil composition

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

The present invention provides a viscosity index improver having an excellent viscosity index improving effect, a lubricant composition having excellent low-temperature viscosity in which the viscosity reduction due to long-term use is small, and a method for producing the lubricant composition. A viscosity index improver of the present invention contains a copolymer (A) containing, as monomer units, an alkyl (meth)acrylate (a) whose alkyl group contains 5 or more carbon atoms, and an alkyl (meth)acrylate (b) whose alkyl group contains 1 to 4 carbon atoms, wherein the alkyl group of the alkyl (meth)acrylate (a) whose alkyl group contains 5 or more carbon atoms has a molar-average carbon number (Q) of 29 or more, and the alkyl (meth)acrylate (b) whose alkyl group contains 1 to 4 carbon atoms is contained as a monomer unit in an amount of 38 to 75% by weight based on the weight of the copolymer (A).

Viscosity index improver, lubricant composition, and method for manufacturing lubricant composition

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Kyoto, Japan

Kenyuu Yoshida