US 12,258,534 B2
Viscosity index improver and lubricating oil composition
Nobuhiro Naito, Kyoto (JP); Satoshi Matsumoto, Kyoto (JP); Masahiro Hashimoto, Kyoto (JP); Kenyuu Yoshida, Kyoto (JP); Hiroki Yamashita, Kyoto (JP); and Ryota Sato, Kyoto (JP)
Assigned to SANYO CHEMICAL INDUSTRIES, LTD., Kyoto (JP)
Appl. No. 18/025,430
Filed by SANYO CHEMICAL INDUSTRIES, LTD., Kyoto (JP)
PCT Filed Sep. 14, 2021, PCT No. PCT/JP2021/033641
§ 371(c)(1), (2) Date Mar. 9, 2023,
PCT Pub. No. WO2022/054957, PCT Pub. Date Mar. 17, 2022.
Claims priority of application No. 2020-154046 (JP), filed on Sep. 14, 2020.
Prior Publication US 2023/0323241 A1, Oct. 12, 2023
Int. Cl. C10M 169/04 (2006.01); C10M 145/14 (2006.01); C10M 149/10 (2006.01); C10N 20/02 (2006.01); C10N 20/04 (2006.01); C10N 30/02 (2006.01); C10N 40/04 (2006.01); C10N 40/08 (2006.01); C10N 40/25 (2006.01)
CPC C10M 169/041 (2013.01) [C10M 145/14 (2013.01); C10M 149/10 (2013.01); C10M 2203/003 (2013.01); C10M 2203/1006 (2013.01); C10M 2207/2815 (2013.01); C10M 2207/2825 (2013.01); C10M 2209/084 (2013.01); C10M 2217/028 (2013.01); C10N 2020/02 (2013.01); C10N 2020/04 (2013.01); C10N 2030/02 (2013.01); C10N 2040/04 (2013.01); C10N 2040/08 (2013.01); C10N 2040/25 (2013.01)] 9 Claims
 
1. A viscosity-index improving agent comprising:
a (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 mm2/s; and
an ester oil (B2) having a kinematic viscosity at 100° C. of 2.51 to 5.00 mm2/s:
wherein a weight ratio {(B1)/(B2)} of the ester oil (B1) to the ester oil (B2) in the viscosity-index improving agent is 25/75 to 75/25,

OG Complex Work Unit Chemistry
wherein R1 is a hydrogen atom or a methyl group; —X1— is a group represented by —O—, —O(AO)m—, 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;
R2 is 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, and
wherein a difference ((B2)−(B1)) in kinematic viscosity at 100° C. between the ester oil (B1) and the ester oil (B2) in the viscosity-index improving agent is 0.88 to 1.3 mm2/s
wherein a ratio {(A)/((B1)+(B2))} of the weight of the (co)polymer (A) to the total weight of the ester oil (B1) and the ester oil (B2) in the viscosity-index improving agent is 15/85 to 43/57, and
wherein, when the viscosity-index improving agent is added to a lubricating oil composition comprising 76.55 wt. % to 86.04 wt. % of a hydrocarbon oil, the lubricating oil composition has a friction coefficient of 0.112 to 0.123,
wherein the friction coefficient is measured using a high-frequency reciprocating rig with a test steel ball made of SUJ2 and having a diameter of 6 mm and a test disk made of SUJ2 under the following conditions:
measurement temperature: 80° C.;
load: 3.92 N (400 g);
stroke: 1000 μm; and
frequency: 20 Hz.