Abstract: Provided is a composition for a refrigeration machine capable of reducing a friction coefficient in friction between sliding members in a refrigeration machine, and a composition kit for a refrigeration machine for providing the composition for a refrigeration machine. A composition for a refrigeration machine of the present disclosure includes a refrigeration machine oil, nanodiamond particles dispersed in the refrigeration machine oil, and a dispersant. The refrigeration machine oil preferably contains a polyvinyl ether, a polyol ester, a polyalkylene glycol, an alkylbenzene, or a mineral oil. The composition kit for a refrigeration machine of the present disclosure includes a refrigeration machine oil (A) containing a base oil and nanodiamond particles dispersed in the base oil, and a refrigerant (B).

Abstract: Provided is a surface-modified nanodiamond having excellent dispersibility in an organic solvent, and a method capable of introducing various surface-modifying groups and easily producing surface-modified nanocarbon particles with little zirconia contamination. The surface-modified nanodiamond includes nanodiamond particles and a group that surface-modifies the nanodiamond particles and is represented by Formula (1): —X—R1 (1) [where X represents —NH—, —O—, —O—C(?O)—, —C(?O)—O—, —NH—C(?O)—, —C(?O)—NH—, or —S—; the bond extending left from X is bonded to a nanodiamond particle; R1 represents a monovalent organic group that does not have a hydroxy group, carboxy group, amino group, mono-substituted amino group, terminal alkenyl group, and terminal epoxy group; an atom bound to X is a carbon atom; and a molar ratio of carbon atoms to the total amount of heteroatoms selected from the group consisting of nitrogen atoms, oxygen atoms, sulfur atoms, and silicon atoms is 4.5 or greater.

Abstract: Provided is a nanodiamond dispersion composition having excellent dispersibility of nanodiamond particles in an organic dispersion medium. A nanodiamond dispersion composition including an organic dispersion medium, nanodiamond particles dispersed in the organic dispersion medium, and a fatty acid ester dispersing agent, the nanodiamond particles being surface-modified by a surface-modifying group or compound containing an organic group. The fatty acid ester dispersing agent preferably has a mass loss rate of 30% or less when held in an air atmosphere at a temperature of 200° C. for 180 minutes.

Abstract: Provided is a surface-modified nanodiamond having excellent dispersibility in an organic solvent, or a surface-modified nanodiamond which is an intermediate for obtaining the surface-modified nanodiamond. Also, provided is a method of producing surface-modified nanocarbon particles, in which various surface-modifying groups can be introduced into the nanocarbon particles. The surface-modified nanodiamond according to the present disclosure includes a nanodiamond particle and a group that surface-modifies the nanodiamond particle, the group being represented by Formula (1) or (2).

Abstract: Provided is a nanodiamond dispersion composition having excellent dispersibility of nanodiamond particles in an organic dispersion medium even when the organic dispersion medium has a small SP value. The nanodiamond dispersion composition according to an embodiment of the present invention includes an organic dispersion medium, nanodiamond particles dispersed in the organic dispersion medium, and a fatty acid ester dispersing agent. The fatty acid ester dispersing agent preferably has a mass loss rate of 20% or less when held in an air atmosphere at a temperature of 200° C. for 180 minutes. The fatty acid ester dispersing agent preferably has an acid value of 40 mgKOH/g or less.

Abstract: Provided is a surface-modified nanodiamond having excellent dispersibility in an organic solvent, and a method capable of introducing various surface-modifying groups and easily producing surface-modified nanocarbon particles with little zirconia contamination. The surface-modified nanodiamond includes nanodiamond particles and a group that surface-modifies the nanodiamond particles and is represented by Formula (1): —X—R1 (1) [where X represents —NH—, —O—, —O—C(?O)—, —C(?O)—O—, —NH—C(?O)—, —C(?O)—NH—, or —S—; the bond extending left from X is bonded to a nanodiamond particle; R1 represents a monovalent organic group that does not have a hydroxy group, carboxy group, amino group, mono-substituted amino group, terminal alkenyl group, and terminal epoxy group; an atom bound to X is a carbon atom; and a molar ratio of carbon atoms to the total amount of heteroatoms selected from the group consisting of nitrogen atoms, oxygen atoms, sulfur atoms, and silicon atoms is 4.5 or greater.