Lubricant composition and lubricating system

Patent metadata

Field	Value
Publication number	US-11124731-B2
Application number	US-201816494584-A
Country	US
Kind code	B2
Filing date	Apr 3, 2018
Priority date	Apr 5, 2017
Publication date	Sep 21, 2021
Grant date	Sep 21, 2021

Abstract

The present invention provides a lubricant composition suitable for reducing friction between sliding members such as those within a pump for circulating a heat medium of a heat pump device, and a lubricating system using the composition as a heat medium. A lubricant composition 10 of the present invention comprises: an antifreeze liquid 11 containing ethylene glycol; and 0.01 mass % or less of nanodiamond particles 12. The nanodiamond particles 12 are preferably detonation nanodiamond particles. The lubricant composition 10 is preferably a liquid composition for a heat pump. In addition, the lubricating system of the present invention uses the lubricant composition 10 as a heat medium.

First claim

The invention claimed is:

1. A lubricant composition comprising:
an antifreeze liquid containing ethylene glycol; and
0.0003 to 0.006 mass % of nanodiamond particles; wherein the zeta potential of the nanodiamond particles is from −50 to −30 mV, wherein the zeta potential is measured by Doppler electrophoresis at a measurement temperature of 25° C.

2. The lubricant composition according to claim 1 , wherein the nanodiamond particles are detonation nanodiamond particles.

3. The lubricant composition according to claim 1 , wherein the lubricant composition is a liquid composition for a heat pump.

4. A lubricating system which uses the lubricant composition described in claim 1 as a heat medium.

5. The lubricant composition according to claim 1 , wherein a content percentage of the antifreeze liquid is 90 mass % or greater.

6. The lubricant composition according to claim 1 , wherein a content percentage of ethylene glycol in the antifreeze liquid is from 10 to 90 mass %.

7. The lubricant composition according to claim 1 , wherein the antifreeze liquid is an ethylene glycol aqueous solution.

8. The lubricant composition according to claim 7 , wherein the ethylene glycol aqueous solution comprises from 25 to 60 mass % of ethylene glycol, and from 40 to 75 mass % of water.

9. The lubricant composition according to claim 1 , wherein a D50 particle size of the nanodiamond particles in the lubricant composition is not greater than 10 nm,
wherein the D50 particle size is measured by dynamic light scattering technique using a noncontact backscatter mode.

10. A lubricant composition according to claim 1 , wherein a content percentage of the nanodiamond particles in the lubricant composition is from 0.0005 to 0.003 mass %.

11. The lubricant composition according to claim 2 , wherein a D50 particle size of the nanodiamond particles in the lubricant composition is not greater than 6 nm,
wherein the D50 particle size is measured by dynamic light scattering technique using a noncontact backscatter mode.

12. The lubricant composition according to claim 11 , wherein a content percentage of the nanodiamond particles in the lubricant composition is from 0.0008 to 0.002 mass %.

13. The lubricant composition according to claim 12 , wherein the ethylene glycol aqueous solution comprises from 25 to 60 mass % of ethylene glycol and from 40 to 75 mass % of water.

14. A lubricating system having the lubricant composition described in claim 1 present between sliding surfaces of two members having the sliding surfaces.

15. The lubricating system according to claim 14 , wherein a material of the sliding surface is a diamond-like carbon.

Assignees

• Daicel Corp

Inventors

• Kimoto Norihiro
• Goto Tomohiro

Classifications

• C10M125/02

  Carbon; Graphite · CPC title

• C01B32/28

  After-treatment, e.g. purification, irradiation, separation or recovery · CPC title

• C10M169/04 Primary

  Mixtures of base-materials and additives · CPC title

• C09K5/10

  Liquid materials · CPC title

• B82Y30/00

  Nanotechnology for materials or surface science, e.g. nanocomposites · CPC title