Viscosity modifier for lubricating oil and lubricating oil composition for hydraulic fluid

Patent metadata

Field	Value
Publication number	US-12398338-B2
Application number	US-202218578257-A
Country	US
Kind code	B2
Filing date	Jul 15, 2022
Priority date	Jul 20, 2021
Publication date	Aug 26, 2025
Grant date	Aug 26, 2025

Abstract

A viscosity modifier for lubricating oil, including an (C) ethylene-α-olefin copolymer having an ethylene molar content rate within a range of 30 to 70 mol %, a rotational viscosity at 150° C. of 300 to 8,000 mPa·s, a Hasen chromaticity of 30 or lower, a molecular weight distribution (Mw/Mn) of 2.5 or less, and a B value of 1.1 or more; a lubricating oil composition with a lubricating oil base oil including a (A) mineral oil having a kinematic viscosity at 40° C. of 10 to 100 mm 2 /s, a viscosity index of 90 or more, and a pour point of 0° C. or lower and/or a (B) synthetic oil having a kinematic viscosity at 40° C. of 4 to 100 mm 2 /s, a viscosity index of 90 or more and a pour point of −30° C. or lower; and the viscosity modifier having has a kinematic viscosity at 40° C. of 28 to 170 mm 2 /s.

First claim

The invention claimed is:

1. A viscosity modifier for lubricating oil, comprising an (C) ethylene-α-olefin copolymer having the following characteristics (C1) to (C5), and (C6):
(C1) an ethylene molar content rate is within a range of 53 to 58 mol %,
(C2) a rotational viscosity at 150° C. is 300 to 8,000 mPa·s,
(C3) a Hasen chromaticity is 30 or lower,
(C4) a molecular weight distribution (Mw/Mn) is 2.0 or more and 2.2 or less in molecular weight obtained in terms of polystyrene, as measured by gel permeation chromatography (GPC),
(C5) a B value represented by the following formula [1] is 1.1 or more:

B
=

P
OE

2
⁢

P
O

·

P
E

n

[
1
]

wherein in the formula [1], P E represents a molar fraction of ethylene component, Po represents a molar fraction of α-olefin component, and P OE represents a molar fraction of ethylene-α-olefin chain in a total dyad chain and (C6) a weight-average molecular weight (Mw) is 20,000 to 30,000 obtained in terms of polystyrene, as measured by gel permeation chromatography (GPC).

2. A lubricating oil composition for hydraulic fluid, comprising: a lubricating oil base oil comprising a (A) mineral oil having the following characteristics (A1) to (A3) and/or a (B) synthetic oil having the following characteristics (B1) to (B3); and the viscosity modifier for lubricating oil according to claim 1 , wherein the lubricating oil composition for hydraulic fluid has a kinematic viscosity at 40° C. of 28 to 170 mm 2 /s:
(A1) a kinematic viscosity at 40° C. is 10 to 100 mm 2 /s,
(A2) a viscosity index is 90 or more,
(A3) a pour point is 0° C. or lower,
(B1) a kinematic viscosity at 40° C. is 4 to 100 mm 2 /s,
(B2) a viscosity index is 90 or more,
(B3) a pour point is −30° C. or lower.

3. The lubricating oil composition for hydraulic fluid according to claim 2 , wherein an ethylene molar content rate of the (C) ethylene-α-olefin copolymer is within a range of 40 to 60 mol %.

4. The lubricating oil composition for hydraulic fluid according to claim 2 , wherein a rotational viscosity of the (C) ethylene-α-olefin copolymer at 150° C. is 1,000 to 5,000 mPa·s.

5. The lubricating oil composition for hydraulic fluid according to claim 2 , wherein an α-olefin of the (C) ethylene-α-olefin copolymer is propylene.

6. The lubricating oil composition for hydraulic fluid according to claim 2 , wherein the content of the (C) ethylene-α-olefin copolymer is 1 to 10% by mass.

7. A hydraulic oil for machine tools, forming machines, or construction machinery, comprising the lubricating oil composition for hydraulic fluid according to claim 2 .

8. A method for producing the viscosity modifier for lubricating oil according to claim 1 , comprising a step of producing the (C) ethylene-α-olefin copolymer by the following method (α):
method (α): a method comprising a step of solution polymerizing ethylene and a C3-C20 α-olefin in the presence of a catalyst system comprising a bridged metallocene compound (a-1′) represented by formula [II-I], and
at least one compound (b) selected from the group consisting of an organometallic compound (b-1), an organoaluminum oxy compound (b-2), and a compound (b-3) that reacts with the bridged metallocene compound (a-1′) to form an ion pair:

wherein in formula [II-I], R 1 , R 2 , R 3 , R 4 , R 5 , R 8 , R 9 , and R 12 are each independently a hydrogen atom, a C1-C20 hydrocarbon group or a silicon-containing hydrocarbon group, and a plurality of adjacent groups are optionally connected together to form a ring structure,
R 6 and R 11 are identical to each other and are each a hydrogen atom, a C1-C20 hydrocarbon group or a silicon-containing hydrocarbon group,
R 7 and R 10 are identical to each other and are each a hydrogen atom, a C1-C20 hydrocarbon group or a silicon-containing hydrocarbon group,
R 6 , R 7 , R 10 and R 11 are not simultaneously hydrogen atoms;
R 6 and R 7 are optionally bonded with a C2-C3 hydrocarbon to form a ring structure,
R 10 and R 11 are optionally bonded with a C2-C3 hydrocarbon to form a ring structure,
R 13 and R 14 are each independently an aryl group;
Y is a carbon atom or a silicon atom;
M is a titanium atom, a zirconium atom, or a hafnium atom;
Q is independently a halogen atom, a C1-C20 hydrocarbon group, an anionic ligand or a neutral ligand capable of coordinating with a lone electron pair; and
j is an integer of 1 to 4.

Assignees

• Mitsui Chemicals Inc

Inventors

• Abe Shota
• Kanaya Hirotaka

Classifications

• C10N2040/08

  Hydraulic fluids, e.g. brake-fluids · CPC title

• C10N2030/02

  Pour-point; Viscosity index · CPC title

• C10N2020/04

  Molecular weight; Molecular weight distribution · CPC title

• C10N2020/02

  Viscosity; Viscosity index · CPC title

• C10M2205/024

  Propene · CPC title