# US 11,993,757 B2 · Lubricating oil composition for shock absorber, additive for friction adjustment, lubricating oil additive, shock absorber, and method for adjusting friction of shock absorber lubricating oil

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- Number: US 11,993,757 B2
- Document ID: US11993757B2
- Status: Granted
- Kind: B2
- Application number: 17/285,175
- Filed: 2019-12-24
- Published: 2021-12-09
- Granted: 2024-05-28
- Earliest claimed: 2018-10-26
- Assignees: KYB Corporation
- Applicants: KYB Corporation
- Inventors: Shinji Kato
- Web page: https://patentgrep.com/patent/US11993757B2

## CPC

- C10M 141/10: at least one of them being an organic phosphorus-containing compound
- C10M 169/04: Mixtures of base-materials and additives
- C10M 2207/022: containing at least two hydroxy groups
- C10M 2207/283: of polyhydroxy compounds
- C10M 2223/045: Metal containing thio derivatives
- C10N 2010/04: Groups 2 or 12
- C10N 2030/06: Oiliness; Film-strength; Anti-wear; Resistance to extreme pressure
- C10N 2040/08: Hydraulic fluids, e.g. brake-fluids
- C10M: LUBRICATING COMPOSITIONS (well drilling compositions C09K8/02); USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION (mould release, i.e. separating, agents for metals B22C3/00, for plastics or substances in a plastic state, in general B29C33/56, for glass C03B40/02; textile lubricating compositions D06M11/00, D06M13/00, D06M15/00; immersion oils for microscopy G02B21/33)
- C10N: INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS

## Abstract

To provide a lubricating oil composition for a shock absorber, an additive for friction adjustment, a lubricating oil additive, a shock absorber, and a method for adjusting friction of a shock absorber lubricating oil, capable of achieving both operation stability and riding comfort. A lubricating oil composition for a shock absorber contains a base oil and a friction adjusting agent, in which the friction adjusting agent contains zinc dithiophosphate and pentaerythritol.

## Claims

### Claim 1

A shock absorber including a lubricating oil composition, the lubricating oil composition comprising:
a base oil; and
a friction adjusting agent, wherein
the friction adjusting agent contains zinc dithiophosphate and pentaerythritol esters and/or pentaerythritol derivatives,
the zinc dithiophosphate has at least one secondary alkyl group having 3 to 5 carbon atoms,
wherein
the pentaerythritol esters and/or pentaerythritol derivatives are contained in 2 to 5 wt. % based on total amount of the lubricating oil composition,
the pentaerythritol esters and/or pentaerythritol derivatives contain pentaerythritol tetraester and/or pentaerythritol tetraester derivative, and
all four terminal substituents of the pentaerythritol tetraester and/or pentaerythritol tetraester derivative are ester-bonded oleic acid residues.

### Claim 2 (depends on 1)

The shock absorber according to claim 1, wherein
the zinc dithiophosphate is contained in an amount of 0.1 wt. % or more and 4.0 wt. % or less in the lubricating oil composition.

### Claim 3 (depends on 1)

The shock absorber according to claim 1, wherein
the zinc dithiophosphate is primary zinc dithiophosphate represented by Formula 1 below,
wherein, in Formula 1, R11 to R14 are alkyl groups, and the alkyl groups have a primary alkyl group and a secondary alkyl group, and one or more and three or less Rs of R11 to R14 are primary alkyl groups and the rest of R11 to R14 are secondary alkyl groups.

### Claim 4 (depends on 2)

The shock absorber according to claim 2, wherein
the friction adjusting agent is configured so as to adjust an amplitude dependent index in a range of 0.3 to 3.0 in addition to the friction coefficient of the composition.

### Claim 5 (depends on 1)

The shock absorber according to claim 1, wherein
the zinc dithiophosphate is a mixture of primary zinc dithiophosphate and secondary zinc dithiophosphate different from the primary zinc dithiophosphate.