Additive for lubricants
An additive for lubricants containing, a ZrO 2 particle coated with a silane coupling agent, and a dispersion medium for the ZrO 2 particle, wherein a BET specific surface area of the ZrO 2 particle coated with the silane coupling agent obtained by removing the dispersion medium is 40% or more of a BET specific surface area of the ZrO 2 particle before coating with the silane coupling agent.
1. An additive for lubricants comprising, a ZrO 2 particle coated with a silane coupling agent, and a dispersion medium for the ZrO 2 particle, wherein a BET specific surface area of the ZrO 2 particle coated with the silane coupling agent obtained by removing the dispersion medium is 40% or more of a BET specific surface area of the ZrO 2 particle before coating with the silane coupling agent.
2. The additive for lubricants according to claim 1 , comprising the ZrO 2 particle coated with the silane coupling agent in an amount of 1 mass % or more and 80 mass % or less.
3. A lubricant composition comprising, the additive for lubricants according to claim 1 .
4. A method for producing an additive for lubricants containing a ZrO 2 particle coated with a silane coupling agent, comprising:
mixing a ZrO 2 particle with a dispersion medium for the ZrO 2 particle; and
reacting the ZrO 2 particle with a silane coupling agent in the obtained mixture until a BET specific surface area of the ZrO 2 particle coated with the silane coupling agent obtained by removing the dispersion medium from the mixture after the reaction of the ZrO 2 particle with the silane coupling agent reaches 40% or more of a BET specific surface area of the ZrO 2 particle before coating with the silane coupling agent.
5. The method for producing an additive for lubricants according to claim 4 , wherein the mixture comprises a catalyst.
6. The method for producing an additive for lubricants according to claim 4 , wherein a reaction temperature of the ZrO 2 particle and the silane coupling agent is 10° C. or more and 100° C. or less.
7. The method for producing an additive for lubricants according to claim 4 , wherein the dispersion medium is removed from the mixture, and resulting powder containing the ZrO 2 particle coated with the silane coupling agent is dispersed in another dispersion medium.
8. A method for producing a lubricant composition comprising, mixing the additive for lubricants according to claim 1 with a lubricant.
9. The method for producing a lubricant composition according to claim 8 , wherein the dispersion medium contained in the additive for lubricants is removed from the mixture of the additive for lubricants and the lubricant.