Composition for freezer, and composition kit for freezer

Abstract

Provided are: a composition for a freezer, which can decrease a friction coefficient in the friction between sliding members in a freezer; and a composition kit for a freezer, which is used for the preparation of the composition for a freezer. The composition for a freezer according to the present disclosure comprises a freezer oil, nano-diamond particles dispersed in the freezer oil, and a dispersing agent. It is preferred for the freezer oil to contain a polyvinyl ether, a polyol ester, a polyalkylene glycol, an alkyl benzene, or a mineral oil. The composition kit for a freezer according to the present disclosure comprises: a freezer oil (A) comprising a base oil and nano-diamond particles dispersed in the base oil; and a cooling medium (B).

Description

Refrigerating machine composition and refrigerator composition kit

[0001] The present disclosure relates to a refrigerator composition and a refrigerator composition kit. More specifically, the present disclosure relates to a refrigerator composition containing a refrigerator oil, and a refrigerator composition kit that is a kit for obtaining the refrigerator composition. This application claims priority from Japanese Patent Application No. 2021-082882, filed in Japan on May 27, 2021, the contents of which are incorporated herein by reference.

[0002] For example, a refrigerator such as a compression type refrigerator is generally composed of a compressor, a condenser, an expansion mechanism (an expansion valve or the like), an evaporator, etc., and has a structure in which a mixture of a refrigerant and a refrigerating machine oil (a refrigerating machine composition) circulates within a sealed system.

[0003] Refrigerating machine oil is used in refrigerator compressors to reduce friction between various sliding parts. The refrigerating machine oil is sealed inside the compressor together with the refrigerant to lubricate sliding parts such as connecting rods and pistons.

[0004] As the composition for refrigerators, for example, a lubricating oil composition containing a specific base oil and a specific nanodiamond is known (see Patent Document 1). The lubricating oil composition is described as having excellent friction properties.

[0005] JP 2020-180248 A JP 2020-76044 A International Publication No. 2020 / 026790

[0006] Conventionally, anti-wear agents such as phosphate esters and oiliness improvers have been used in compressors for refrigerators, but in a mixed lubrication state that occurs depending on the installation state and operating conditions, there is a risk of wear and seizure occurring, which could damage the equipment. Although the lubricant composition described in Patent Document 1 is said to have excellent friction properties, there are concerns about the dispersibility of nanodiamond particles in the base oil, and there is a risk that the reduction in the friction coefficient will be insufficient.

[0007] Patent Document 2 discloses a lubricant composition for initial break-in containing nanocarbon particles, and Patent Document 3 discloses a dispersion in which specific surface-modified nanodiamonds are dispersed in an organic solvent.

[0008] However, Patent Document 2 does not disclose a test (e.g., a ring-on-disk friction test) that simulates friction occurring in a refrigerator compressor. Furthermore, Patent Document 3 does not disclose that the dispersion is effective as a lubricant for sliding members in a refrigerator. Thus, Patent Documents 2 and 3 do not disclose the use of the lubricant composition or the dispersion as a refrigerator oil or in combination with a refrigerant as a refrigerator composition.

[0009] Therefore, an object of the present disclosure is to provide a refrigerator composition that can reduce the coefficient of friction between sliding members in a refrigerator, and a refrigerator composition kit for obtaining the refrigerator composition.

[0010] As a result of intensive research to achieve the above object, the inventors of the present disclosure have found that a composition for a refrigerator containing a refrigerator oil, nanodiamond particles dispersed in the refrigerator oil, and a dispersant can reduce the coefficient of friction between sliding members in a refrigerator. The present disclosure relates to a product that has been completed based on these findings.

[0011] The present disclosure provides a composition for a refrigerator comprising a refrigerator oil, nanodiamond particles dispersed in the refrigerator oil, and a dispersant.

[0012] The refrigerating machine oil preferably contains polyvinyl ethers, polyol esters, polyalkylene glycols, alkylated aromatic hydrocarbon compounds, or mineral oils.

[0013] The dispersant preferably contains a dispersant (I) having a mass average molecular weight of 500 or more and an amine value of 15 mgKOH / g or more, and / or a fatty acid ester-based dispersant (II).

[0014] The SP value of the above refrigerating machine oil is 6.0 to 12.0 (cal / cm 3 ) 1 / 2 It is preferable that:

[0015] The above-mentioned composition for a refrigerator preferably has a friction coefficient of 0.08 or less when used as a lubricant in a ring-on-disk friction test under conditions of a surface pressure of 2 MPa and a speed of 1.5 m / s.

[0016] The composition for refrigerators is preferably used for refrigerator compressors.

[0017] The refrigerator is preferably an air conditioner.

[0018] The present disclosure also provides a refrigeration composition kit comprising a refrigeration oil (A) containing a base oil and nanodiamond particles dispersed in the base oil, and a refrigerant (B).

[0019] The refrigerating machine oil (A) preferably has a friction coefficient of 0.08 or less when used as a lubricant in a ring-on-disk friction test under conditions of a surface pressure of 2 MPa and a speed of 1.5 m / s.

[0020] The refrigerator composition of the present disclosure can reduce the coefficient of friction between sliding members in a refrigerator. Furthermore, the refrigerator composition of the present disclosure can quickly reduce the coefficient of friction. Furthermore, the refrigerator composition kit of the present disclosure can obtain the refrigerator composition by mixing a refrigerating machine oil and a refrigerant.

[0021] 1 is a graph showing the coefficients of friction measured in a ring-on-disk friction test (in the atmosphere, sliding speed of 0.5 m / s) when the refrigerator compositions of Example 1 and Comparative Example 1 are used as lubricants. FIG. 2 is a graph showing the coefficients of friction measured in a ring-on-disk friction test (in the atmosphere, sliding speed of 1.5 m / s) when the refrigerator compositions of Example 1 and Comparative Example 1 are used as lubricants. FIG. 3 is a graph showing the coefficients of friction measured in a ring-on-disk friction test (in the atmosphere, sliding speed of 2.5 m / s) when the refrigerator compositions of Example 1 and Comparative Example 1 are used as lubricants. FIG. 4 is a graph showing the amount of wear measured in a ring-on-disk friction test (in the atmosphere) when the refrigerator compositions of Example 1 and Comparative Example 1 are used as lubricants. FIG. 5 is a graph showing the coefficients of friction measured in a ring-on-disk friction test (in a refrigerant, sliding speed of 0.5 m / s) when the refrigerator compositions of Example 1 and Comparative Example 1 are used as lubricants. 1 is a graph showing the coefficients of friction measured in a ring-on-disk friction test (in a refrigerant, sliding speed of 1.5 m / s) when the refrigerant compositions of Example 1 and Comparative Example 1 are used as lubricants. FIG. 2 is a graph showing the coefficients of friction measured in a ring-on-disk friction test (in a refrigerant, sliding speed of 2.5 m / s) when the refrigerant compositions of Example 1 and Comparative Example 1 are used as lubricants. FIG. 3 is a graph showing the amount of wear measured in a ring-on-disk friction test (in a refrigerant) when the refrigerant compositions of Example 1 and Comparative Example 1 are used as lubricants. FIG. 4 is a graph showing the coefficients of friction measured in a ring-on-disk friction test (in a refrigerant, sliding speed of 0.5 m / s) when the refrigerant compositions of Example 2 and Comparative Example 1 are used as lubricants. FIG. 5 is a graph showing the coefficients of friction measured in a ring-on-disk friction test (in a refrigerant, sliding speed of 1.5 m / s) when the refrigerant compositions of Example 2 and Comparative Example 1 are used as lubricants. 1 is a graph showing the coefficient of friction measured in a ring-on-disk friction test (in a refrigerant, sliding speed 2.5 m / s) when the refrigerating machine compositions of Example 2 and Comparative Example 1 are used as lubricants. 2 is a graph showing the amount of wear measured in a ring-on-disk friction test (in a refrigerant) when the refrigerating machine compositions of Example 2 and Comparative Example 1 are used as lubricants.

[0022] [Refrigerator composition] A refrigerator composition according to one embodiment of the present disclosure comprises at least a refrigerator oil, nanodiamond particles dispersed in the refrigerator oil, and a dispersant. The refrigerator composition is filled into a refrigerator for use. The nanodiamond particles are dispersed in at least the refrigerator oil.

[0023] (Refrigerating Machine Oil) The above-mentioned refrigerating machine oil may be a known or conventional refrigerating machine oil such as a synthetic oil or a mineral oil used in a conventional refrigerating machine composition. Examples of the refrigerating machine oil include polyvinyl ethers (PVEs), polyol esters (POEs), polyalkylene glycols (PAGs), polyesters, polycarbonates, hydrogenated α-olefin oligomers, alicyclic hydrocarbon compounds, alkylated aromatic hydrocarbon compounds such as alkylbenzenes (ABs), and mineral oils. Examples of mineral oils include oils obtained by vacuum distillation of atmospheric residual oils obtained by atmospheric distillation of crude oils such as paraffinic crude oil, intermediate crude oil, and naphthenic crude oil, and then refining the lubricating oil fraction by solvent deasphalting, solvent extraction or hydrocracking, solvent dewaxing or catalytic dewaxing, hydrorefining, etc.; oils produced by isomerizing mineral oil wax; and oils produced by hydroisomerization dewaxing of residual wax (gas-to-liquid wax) in GTL processes such as the Fischer-Tropsch process. Among these, polyvinyl ethers, polyol esters, polyalkylene glycols, alkylated aromatic hydrocarbon compounds, and mineral oils are preferred from the viewpoints of excellent dispersibility of nanodiamond particles, compatibility with refrigerants, and hydrolysis resistance. The above-mentioned refrigeration oils may be used alone or in combination of two or more.

[0024] The polyvinyl ethers are polymers containing structural units derived from vinyl ethers. Among them, from the viewpoint of obtaining better stability, polymers containing structural units derived from vinyl ethers having an alkyl group having 1 to 4 carbon atoms in the side chain are preferred.

[0025] The SP value of the refrigerating machine oil [Hildebrand solubility parameter (δ) at 25°C, unit: (cal / cm 3 )1 / 2 ] is preferably 6.0 to 12.0, more preferably 6.0 or more and less than 11.0. When the SP value of the refrigerating machine oil is within the above range, the dispersibility of the nanodiamond particles is excellent and the compatibility with the refrigerant is also excellent.

[0026] The content of the refrigerating machine oil in the refrigerating machine composition is not particularly limited, but is, for example, 1 to 99 mass %, and preferably 20 to 95 mass %, relative to the total amount of the refrigerating machine composition.

[0027] (Nanodiamond Particles) The nanodiamond particles are not particularly limited, and known or conventional nanodiamond particles can be used. The nanodiamond particles may be surface-modified nanodiamond (surface-modified nanodiamond) particles, or may be non-surface-modified nanodiamond particles. Note that non-surface-modified nanodiamond particles have hydroxyl groups (-OH) or carboxyl groups (-COOH) on the surface. Only one type of nanodiamond particle may be used, or two or more types may be used.

[0028] The nanodiamond particles preferably include primary nanodiamond particles, and may also include secondary particles formed by aggregation of a plurality of the primary particles.

[0029] As the nanodiamond particles, for example, detonation nanodiamonds (i.e., nanodiamonds produced by detonation) and high-temperature high-pressure nanodiamonds (i.e., nanodiamonds produced by high-temperature high-pressure) can be used. Among them, detonation nanodiamonds are preferred because they have better dispersibility in the refrigerator composition, i.e., the particle size of the primary particles is in the single digit nanometers.

[0030] The above-mentioned detonation nanodiamond includes air-cooled detonation nanodiamond (i.e., the nanodiamond produced by air-cooled detonation method) and water-cooled detonation nanodiamond (i.e., the nanodiamond produced by water-cooled detonation method).Among them, air-cooled detonation nanodiamond is preferred because its primary particle is smaller than that of water-cooled detonation nanodiamond.

[0031] In the above-mentioned surface-modified nanodiamonds, examples of the compounds or functional groups that modify the surface of the nanodiamond particles include silane compounds, phosphonate ions or phosphonate residues, surface-modifying groups having a vinyl group at the end, amide groups, cations of cationic surfactants, groups containing polyglycerin chains, and groups containing polyethylene glycol chains.

[0032] In the surface-modified nanodiamonds, the compound or functional group that modifies the nanodiamond particles preferably contains an organic group. The organic group is more preferably an organic group having 4 or more carbon atoms (e.g., 4-25), even more preferably an organic group having 6 or more carbon atoms (e.g., 6-22), and particularly preferably an organic group having 8 or more carbon atoms (e.g., 8-20). When the surface-modifying compound or functional group contains an organic group (e.g., an organic group having 4 or more carbon atoms), the hydrophobic interaction between the organic group and the refrigerating machine oil improves the dispersibility of the nanodiamond particles in the refrigerating machine oil. Examples of the organic group include substituted or unsubstituted hydrocarbon groups, substituted or unsubstituted heterocyclic groups, and groups in which two or more of the above hydrocarbon groups and / or the above heterocyclic groups are bonded. Specific examples of the organic group include the organic groups in the monovalent organic groups exemplified and explained as R in formula (I) below.

[0033] The surface modifying group is preferably a group represented by the following formula (I). That is, the nanodiamond particles are preferably surface-modified nanodiamonds (nanodiamond particles) in which the surface of the nanodiamond particles is modified with a group represented by the following formula (I): -X-R (I) [In formula (I), X represents a linking group, and the bond extending to the left from X is bonded to the nanodiamond. R represents a monovalent organic group, and the atom bonded to X is a carbon atom.]

[0034] In the above formula (I), X represents a linking group, for example, an amino group (—NR a-), ether bond (-O-), ester bond (-C(=O)O-), phosphinic acid group (-PH(=O)O-), phosphonic acid group (-P(-OH)(=O)O-), phosphate ester (-O-P(=O)(OH)-O-), sulfide bond (-S-), carbonyl group (-C(=O)-), amide group (-C(=O)-NR a -), urethane bond (-R a H-C(=O)-O-), imide bond (-C(=O)-NR a Examples include -C(=O)-), thiocarbonyl group (-C(=S)-), siloxane bond (-Si-O-), sulfate ester group (-O-S(=O)2-O-), sulfonyl group (-S(=O)2-O-), sulfone group (-S(=O)2-), sulfoxide (-S(=O)-), and groups in which two or more of these are bonded. In asymmetric divalent groups, there are no particular restrictions on the direction of the divalent group relative to the nanodiamond side and the R side. In addition, the R a represents a hydrogen atom or a monovalent organic group. a Examples of the monovalent organic group in include those exemplified and explained as the monovalent organic group in R above.

[0035] Examples of the monovalent organic group in R include substituted or unsubstituted hydrocarbon groups (monovalent hydrocarbon groups), substituted or unsubstituted heterocyclic groups (monovalent heterocyclic groups), and groups in which two or more of the above-mentioned monovalent hydrocarbon groups and / or monovalent heterocyclic groups are bonded together.The bonded groups may be bonded directly or via a linking group.Examples of the linking group include an amino group, an ether bond, an ester bond, a phosphinic acid group, a sulfide bond, a carbonyl group, an organic group-substituted amide group, an organic group-substituted urethane bond, an organic group-substituted imide bond, a thiocarbonyl group, a siloxane bond, and groups in which two or more of these are bonded together.

[0036] Examples of the hydrocarbon group in the monovalent organic group include an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, and groups in which two or more of these groups are bonded together.

[0037] Examples of the aliphatic hydrocarbon group include an alkyl group, an alkenyl group, and an alkynyl group. Examples of the alkyl group include a C group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a hexyl group, an octyl group, an isooctyl group, a decyl group, and a dodecyl group. 1-22 Alkyl group (preferably C 2-20 alkyl group, more preferably C 3-18 Examples of the alkenyl group include C groups such as vinyl group, allyl group, methallyl group, 1-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl group, 5-hexenyl group, and oleyl group. 2-22 Alkenyl group (preferably C 4-20 Alkenyl groups, more preferably C 8-18 Examples of the alkynyl group include C alkynyl groups such as ethynyl and propynyl groups. 2-22 Alkynyl group (preferably C 4-20 Alkynyl groups, more preferably C 8-18 alkynyl groups).

[0038] Examples of the alicyclic hydrocarbon group include a C group such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclododecyl group. 3-12 Cycloalkyl group; C such as cyclohexenyl group 3-12 Cycloalkenyl group; C such as bicycloheptanyl group, bicycloheptenyl group 4-15 Examples include a bridged cyclic hydrocarbon group.

[0039] Examples of the aromatic hydrocarbon group include C groups such as phenyl and naphthyl groups. 6-14 Aryl groups (especially C 6-10 aryl groups).

[0040] Examples of heterocycles constituting the heterocyclic group include aromatic heterocycles and non-aromatic heterocycles. Examples of such heterocycles include 3- to 10-membered rings (preferably 4- to 6-membered rings) containing carbon atoms and at least one heteroatom (e.g., oxygen atom, sulfur atom, nitrogen atom, etc.) as ring-constituting atoms, and condensed rings thereof. Specific examples include heterocycles containing an oxygen atom as a heteroatom (e.g., 3-membered rings such as an oxirane ring; 4-membered rings such as an oxetane ring; 5-membered rings such as a furan ring, tetrahydrofuran ring, oxazole ring, isoxazole ring, γ-butyrolactone ring; 6-membered rings such as a 4-oxo-4H-pyran ring, tetrahydropyran ring, morpholine ring; condensed rings such as a benzofuran ring, isobenzofuran ring, 4-oxo-4H-chromene ring, chroman ring, isochroman ring); 3-oxatricyclo[4.3.1.1 4,8 ] undecan-2-one ring, 3-oxatricyclo[4.2.1.0 4,8 ] nonan-2-one ring and the like), heterocycles containing a sulfur atom as a heteroatom (for example, 5-membered rings such as a thiophene ring, a thiazole ring, an isothiazole ring, a thiadiazole ring, and the like; 6-membered rings such as a 4-oxo-4H-thiopyran ring, and the like; fused rings such as a benzothiophene ring, and the like), heterocycles containing a nitrogen atom as a heteroatom (for example, 5-membered rings such as a pyrrole ring, a pyrrolidine ring, a pyrazole ring, an imidazole ring, and a triazole ring, and the like; 6-membered rings such as an isocyanuric ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a piperidine ring, and a piperazine ring, and the like; indole ring, indoline ring, quinoline ring, acridine ring, a naphthyridine ring, a quinazoline ring, and a fused ring such as a purine ring, and the like).

[0041] Examples of the group in which an aliphatic hydrocarbon group and an alicyclic hydrocarbon group are bonded include a cyclohexylmethyl group and a methylcyclohexyl group. Examples of the group in which an aliphatic hydrocarbon group and an aromatic hydrocarbon group are bonded include C groups such as a benzyl group and a phenethyl group. 7-18 Aralkyl groups (especially C 7-10 C groups such as aralkyl groups, cinnamyl groups, etc. 6-10 Aryl-C 2-6 C such as alkenyl group, tolyl group 1-4 C such as alkyl-substituted aryl group, styryl group 2-4Alkenyl-substituted aryl groups and the like are included.

[0042] Examples of the group in which two or more of the monovalent hydrocarbon groups and / or monovalent heterocyclic groups are bonded via a linking group include a group in which the monovalent hydrocarbon group and / or the monovalent heterocyclic group is bonded to an alkoxy group, an alkenyloxy group, an alkynyloxy group, an aryloxy group, an aralkyloxy group, an acyloxy group, an alkylthio group, an alkenylthio group, an arylthio group, an aralkylthio group, an acyl group, an alkenylcarbonyl group, an arylcarbonyl group, an aralkylcarbonyl group, an alkoxycarbonyl group, an alkenyloxycarbonyl group, an aryloxycarbonyl group, an aralkyloxycarbonyl group, a dialkylamino group, an acylamino group, an oxetanyl group-containing group, a carbamoyl group, or a group in which two or more of these are bonded.

[0043] The monovalent organic group may have a substituent, for example, a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, a cyano group, an isocyanate group, an isothiocyanate group, a hydroxy group, a carboxy group, an amino group, a mono-substituted amino group, a thiol group, or a phosphate group.

[0044] Of the groups represented by the above formula (I), groups represented by the following formula (1) and groups containing a polyglycerin chain are preferred: -X 1 -R 1 (1) [In formula (1), X 1 represents —O—Si—, —Si—, —NH—, —O—, —O—C(═O)—, —C(═O)—O—, —NH—C(═O)—, —C(═O)—NH—, or —S—; X 1 The bond extending to the left from R binds to the nanodiamond. 1 represents a substituted or unsubstituted monovalent hydrocarbon group, and X 1 The atom bonded to is a carbon atom.

[0045] The above R 1The number of carbon atoms in the refrigerant oil is preferably 4 to 25, more preferably 6 to 22, and even more preferably 8 to 20. When the number of carbon atoms is 4 or more, the steric hindrance between the surface modifying groups is sufficient, and the refrigerant oil is easily dispersed. When the number of carbon atoms is 25 or less, the surface modifying groups are prevented from becoming entangled with each other, and the refrigerant oil is easily dispersed.

[0046] The above R 1 The monovalent hydrocarbon group in may have the above-mentioned substituent. It is also preferable that the monovalent hydrocarbon group does not have a functional group containing active hydrogen (such as a hydroxy group, a carboxy group, an amino group, a mono-substituted amino group, a thiol group, or a phosphate group).

[0047] The above R 1 preferably contains a hydrocarbon group having four or more consecutive carbon atoms in a straight chain. Examples of such a hydrocarbon group include linear alkylene groups such as tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, and decamethylene; branched alkylene groups such as 2-ethylhexamethylene; linear alkenylene groups such as 1-butenylene, 2-butenylene, 1-pentenylene, 2-pentenylene, and 3-pentenylene; branched alkenylene groups such as 2-methyl-2-butenylene; alicyclic hydrocarbon groups having four or more carbon atoms such as cyclohexyl; and aromatic hydrocarbon groups having six or more carbon atoms such as phenyl.

[0048] In formula (1), the 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 preferably 4.5 or more, more preferably 5 or more, and even more preferably 5.5 or more. When the molar ratio is 4.5 or more, the dispersibility in refrigerating machine oil is superior. The molar ratio is not particularly limited, but may be, for example, 22 or less, or 20 or less.

[0049] In the above formula (1), X 1is preferably —O—Si—, —O—, —O—C(═O)—, —C(═O)—O—, or —NH—. In this case, it is possible to more easily produce a surface-modified nanodiamond that has excellent dispersibility in refrigerating machine oil.

[0050] In the above formula (1), X 1 is —O—Si—, —O—, —O—C(═O)—, or —C(═O)—O—, R 1 is more preferably a linear or branched hydrocarbon group having 8 to 20 carbon atoms.

[0051] In the above formula (1), X 1 is —NH—, R 1 is preferably a substituted or unsubstituted aliphatic hydrocarbon group containing 8 to 20 carbon atoms, more preferably a substituted or unsubstituted unsaturated aliphatic hydrocarbon group. 1 is preferably a monovalent hydrocarbon group containing a hydrocarbon group having four or more consecutive carbon atoms in a linear chain.

[0052] Examples of the group containing a polyglycerin chain include a group having a polyglyceryl group and a group in which the hydrogen atoms of at least some of the hydroxy groups in the polyglyceryl group have been substituted with monovalent organic groups.

[0053] The group containing a polyglycerin chain is preferably a polyglycerin chain-containing surface modifying group represented by the following formula (2): -(X 2 C3H5)-(OC3H5)p-(X 3 R 2 ) q (2) [In formula (2), p represents an integer of 1 or more, and q represents an integer that satisfies q = p + 2. X 2 represents a divalent group, [X 2 X in 2 The bond extending to the left from [X 3 R 2 ] represents the end of the polyglycerol chain, and X 3 represents a single bond or a divalent group, and R 2 represents a hydrogen atom or a monovalent organic group.

[0054] [X in the above formula (2)]2 C3H5] is [-X 2 -CH2-C(-)H-CH2-]. 2 X in 2 is bonded to the nanodiamond, and the two Cs are O in [OC3H5] or [X 3 R 2 ]X in 3 The above [X 2 X in 2 represents a divalent group.

[0055] Examples of the divalent group include the divalent groups exemplified and explained as X in formula (I) above. Among the divalent groups, —NR a -, -O-, -C(=O)O-, -PH(=O)O-, and -S- are preferred, and -NR a -, -O-, or -C(=O)O-.

[0056] The [OC3H5] with p in the above formula (2) is a structure derived from glycerin represented by [—O—CH2—C(—)H—CH2—], and [X 2 The polyglycerol chain is formed together with [OC3H5]. p represents a repeating unit of [OC3H5] and is an integer of 1 or more, preferably 3 to 20, and more preferably 5 to 15. p may be the same or different in the group containing multiple polyglycerol chains.

[0057] In the above formula (2), [X 3 R 2 ] indicates the end of the polyglycerol chain, and [X 2 It bonds to C in [C3H5] or C in [OC3H6]. 2 represents a hydrogen atom or a monovalent organic group.

[0058] The above [X 3 R 2 ]X in 3 represents a single bond or a divalent group, and the divalent group is one of the above-mentioned [X 2 X in C3H5 2 Examples of the divalent groups include those exemplified and explained as X 3 Among others, -NR a-, -O-, -C(=O)O-, -O-C(=O)-, -PH(=O)O-, -O-P(=O)(OH)-O-, -S-, -O-S(=O)2-O-, and -O-S(=O)2- are preferred, and -NR a - or -O-. 2 X in 2 and the above [X 3 R 2 ]X in 3 and may be the same or different. 3 R 2 ] may be the same or different. 3 R 2 ]X in 3 may be the same or different in the group containing multiple polyglycerol chains. q represents an integer of 3 or more, the value of which depends on the value of p, and satisfies the equation q = p + 2. q may be the same or different in the group containing multiple polyglycerol chains.

[0059] The above R 2 is a monovalent organic group, the plurality of R 2 are preferably the same. Examples of the monovalent organic group include those exemplified and explained as the monovalent organic group for R in formula (1) above. Among them, substituted or unsubstituted hydrocarbon groups (monovalent hydrocarbon groups), substituted or unsubstituted heterocyclic groups (monovalent heterocyclic groups), and groups in which two or more of these are bonded together are exemplified. In addition, the monovalent organic group may be in the form of an ion.

[0060] The bonded group may be directly bonded or may be bonded via a linking group. The hydrocarbon group in the substituted or unsubstituted hydrocarbon group is preferably an alkyl group, more preferably an alkyl group having 1 to 18 carbon atoms, still more preferably an alkyl group having 1 to 6 carbon atoms, and particularly preferably an ethyl group, a propyl group, a butyl group, or a hexyl group.

[0061] [X 3 R 2Specific examples of the aryl group include OH, NH, CH, an alkoxy group, an acyl group, a mono- or di-alkylamino group, a mono- or di-alkenylamino group, an alkylamide group, an alkenylamide group, a quaternary ammonium-substituted alkoxy group, a chlorine-substituted alkoxy group, and a polyalkylene oxide group.

[0062] The number-average degree of polymerization of glycerin in the polyglycerin chain is preferably 1 to 100, more preferably 2 to 40, and even more preferably 3 to 20. A high number-average degree of polymerization ensures sufficient repulsive forces between nanodiamonds, further increasing the dispersibility of nanodiamonds in refrigerator compositions. A number-average degree of polymerization of 100 or less inhibits entanglement of polyglycerin chains between nanodiamond particles, thereby improving the dispersibility of nanodiamond particles in refrigerator compositions. The number-average degree of polymerization is defined as the number of glycidol units constituting the polyglycerin chain in the group bonded to the surface functional group 1 of the raw nanodiamond. The number of surface functional groups of the raw nanodiamond can be determined by measuring the elemental analysis value or acid value of the raw nanodiamond, or by combining these two methods.

[0063] The mass ratio of nanodiamond to surface-modifying group in the surface-modified nanodiamond [nanodiamond / surface-modifying group] is not particularly limited, but is preferably 0.5 to 1.0, more preferably 0.6 to 0.8. When the mass ratio is 0.5 or more (particularly 0.6 or more), the properties of the nanodiamond are less likely to be impaired. When the mass ratio is 1.0 or less (particularly 0.8 or less), the degree of modification with the surface-modifying group is sufficient, resulting in better dispersibility in refrigerating machine oil. The mass ratio is determined based on the weight loss rate measured by thermogravimetric analysis, with the reduced weight being the mass of the surface-modifying group.

[0064] In the refrigeration composition, nanodiamond particles are dispersed in the refrigeration oil. The nanodiamond particles are preferably dispersed on the nanometer order in the refrigeration composition. The average dispersed particle size (D50, median diameter) of the nanodiamond particles in the refrigeration composition is preferably 2 to 240 nm, more preferably 4 to 200 nm, even more preferably 5 to 100 nm, even more preferably 6 to 70 nm, even more preferably 10 to 60 nm, even more preferably 10 to 40 nm, and particularly preferably 11 to 30 nm. The average dispersed particle size can be measured by dynamic light scattering. When the average dispersed particle size of the nanodiamond particles is within the above range, the nanodiamond particles are well dispersed in the refrigeration composition, and the coefficient of friction can be sufficiently reduced.

[0065] The content of nanodiamond particles in the refrigerating composition is preferably 1 to 10,000 ppm by mass, more preferably 5 to 1,000 ppm by mass, and even more preferably 10 to 500 ppm by mass, relative to the total amount of refrigerating oil. A content of 1 ppm by mass or greater can more sufficiently reduce the coefficient of friction between sliding components in a refrigerator. A content within the above range improves the dispersibility of the nanodiamond particles. The refrigerating composition may also be a concentrated solution that is diluted before use to reduce the nanodiamond particle content. Therefore, the content may be greater than 10,000 ppm by mass or greater than 2% by mass. Because the refrigerating composition has excellent nanodiamond particle dispersibility, even when the content exceeds 10,000 ppm by mass, the nanodiamond particles can be dispersed with a small particle size while reducing the amount of dispersant added. The content is preferably 10% by mass or less to improve the dispersibility of the nanodiamond particles.

[0066] The content of the nanodiamond particles can be calculated from the absorbance at 350 nm.In addition, when the content of surface-modified nanodiamond particles is low concentration (for example, 2000 mass ppm or less), the compound that surface-modifies the nanodiamond particles can be detected by high-frequency inductively coupled plasma atomic emission spectroscopy (ICP atomic emission spectroscopy), and the content can be determined based on the detected amount.

[0067] (Dispersant) The refrigerating machine composition contains a dispersant. By incorporating a dispersant, the dispersibility of nanodiamond particles in the refrigerating machine oil is improved. As the dispersant, a dispersant having a mass average molecular weight of 500 or more and an amine value of 15 mg KOH / g or more (sometimes referred to as "dispersant (I)") or a fatty acid ester-based dispersant (sometimes referred to as "dispersant (II)") is preferred. By using such a dispersant, the dispersibility of nanodiamond particles in the refrigerating machine composition is particularly excellent. The dispersant may be used alone or in combination of two or more types.

[0068] The mass average molecular weight of the dispersant (I) is 500 or more, preferably 650 or more, and more preferably 950 or more. The mass average molecular weight is preferably 20,000 or less, and more preferably 10,000 or less. In this specification, the mass average molecular weight is a molecular weight measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0069] The amine value of the dispersant (I) is 15 mgKOH / g or more, preferably 18 mgKOH / g or more, more preferably 20 mgKOH / g or more, and even more preferably 30 mgKOH / g or more, and is preferably 100 mgKOH / g or less, more preferably 90 mgKOH / g or less, and even more preferably 60 mgKOH / g or less.

[0070] As the dispersant (I), compounds having a structure derived from polyalkylene glycol monoalkyl ether (particularly a structure derived from polyethylene glycol monoalkyl ether or a structure derived from polypropylene glycol monoalkyl ether), compounds having a carbamate structure, and compounds having a structure derived from polycaprolactone are preferred. Each of the above compounds may contain only one type, or may contain two or more types. Furthermore, one compound may alone have one or two or more of the above structures.

[0071] Commercially available dispersants (I) can also be used. Examples of commercially available dispersants (I) include those sold under the trade names "DISPERBYK-2008", "BYK-9076", "BYK-9077", and "ANTI-TERRA-U" (all manufactured by BYK-Chemie).

[0072] The acid value of the dispersant (II) is preferably 40 mgKOH / g or less, more preferably 35 mgKOH / g or less, even more preferably 30 mgKOH / g or less, even more preferably 20 mgKOH / g or less, and particularly preferably 6 mgKOH / g or less. The acid value may be, for example, 0.1 mgKOH / g or more, 0.3 mgKOH / g or more, or 0.5 mgKOH / g or more. When the acid value is 40 mgKOH / g or less (particularly 30 mgKOH / g or less), the dispersibility in the refrigerating machine oil tends to be more excellent.

[0073] The amine value of the dispersant (II) is preferably 5 mgKOH / g or less, more preferably 1 mgKOH / g or less, even more preferably 0.5 mgKOH / g or less, still more preferably 0.1 mgKOH / g or less, and particularly preferably 0 mgKOH / g.

[0074] The dispersant (II) preferably has an average molecular weight Mp of 300 or more, more preferably 1000 or more (e.g., 1000 to 100,000), and even more preferably 3000 or more (e.g., 3000 to 10,000). When the average molecular weight Mp is 300 or more, the dispersibility in the refrigerating machine oil tends to be better. The average molecular weight Mp is a molecular weight measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0075] The dispersant (II) preferably exhibits a mass loss rate (sometimes referred to as "200°C 180-minute mass loss rate") of 30% or less when maintained in an air atmosphere at 200°C for 180 minutes, more preferably 25% or less, even more preferably 20% or less, and particularly preferably 15% or less. When the mass loss rate is 30% or less, the composition for a refrigerator exhibits excellent heat resistance and dispersion stability in high-temperature environments. The mass loss rate can be measured by thermogravimetry-differential thermal analysis (TG-DTA).

[0076] The dispersant (II) may have an acidic functional group, such as a carboxylic acid, a sulfonic acid, or a salt thereof.

[0077] Examples of fatty acids constituting the fatty acid ester-based dispersant (II) include carboxylic acids, sulfonic acids, and salts thereof. Examples of the carboxylic acids include aliphatic monocarboxylic acids such as acetic acid, propionic acid, caprylic acid, nonanoic acid, capric acid, octylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, isononanoic acid, and arachic acid; and aromatic monocarboxylic acids such as benzoic acid and p-(t-butylbutyl)benzoic acid. Examples of the sulfonic acids include naphthalenesulfonic acid. The fatty acids are preferably higher fatty acids. That is, the dispersant (II) is preferably a higher fatty acid ester dispersant. The fatty acids may be used singly or in combination of two or more.

[0078] Examples of compounds constituting the ester component of the fatty acid ester dispersant (II) include cyclic ester compounds such as propiolactone, valerolactone, and caprolactone; condensates of glycols and dibasic acids; and glycerin. The polyester in the fatty acid ester dispersant preferably has a molecular weight of approximately 300 to 9,000, more preferably 400 to 6,000. Specific examples of dispersant (II) include glycerol monooleate.

[0079] Commercially available products can also be used as the dispersant (II). Examples of commercially available fatty acid ester dispersants include those sold under the trade names "Ajisper PA111" and "Ajisper PN411" (both manufactured by Ajinomoto Fine-Techno Co., Ltd.) and "Rheodor MO-60" (manufactured by Kao Corporation).

[0080] Dispersant (II) has high heat resistance and is therefore unlikely to decompose due to heat. Therefore, even when the temperature of the composition for refrigerators rises during use or when used in a high-temperature environment, the composition for refrigerators has excellent dispersion stability in a high-temperature environment and is unlikely to discolor. Furthermore, since dispersant (II) is commercially available and easily available, there is no need to produce it through a complicated production process, and it is easy to produce.

[0081] The content of the dispersant in the above-mentioned refrigerator composition is preferably 100 to 10,000 parts by mass, more preferably 200 to 5,000 parts by mass, and even more preferably 400 to 2,000 parts by mass, per 100 parts by mass of the total amount of nanodiamond particles.

[0082] (Refrigerant) The refrigerating machine oil composition may further contain a refrigerant. The refrigerant may be a known or conventional refrigerant used in conventional refrigerating machine compositions. Examples of the refrigerant include fluorocarbon refrigerants, hydrocarbon (HC) refrigerants which are natural refrigerants, carbon dioxide, ammonia, etc. When the refrigerating machine oil composition contains a refrigerant, a portion of the nanodiamond particles may be dispersed in the refrigerant. Only one type of the refrigerant may be used, or two or more types may be used.

[0083] Among these, fluorinated hydrocarbon refrigerants are preferred as the refrigerant, and examples of the fluorinated hydrocarbon refrigerant include saturated fluorinated hydrocarbon refrigerants and unsaturated fluorinated hydrocarbon refrigerants.

[0084] Examples of the saturated fluorinated hydrocarbon compound include alkane fluorides. The alkane is preferably an alkane having 1 to 4 carbon atoms, more preferably an alkane having 1 to 3 carbon atoms, and even more preferably an alkane having 1 to 2 carbon atoms. Specific examples of the alkane fluorides include trifluoromethane, difluoromethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,2-trifluoroethane, 1,1,1,2-tetrafluoroethane, 1,1,2,2-tetrafluoroethane, and 1,1,1,2,2-pentafluoroethane.

[0085] Examples of the unsaturated fluorinated hydrocarbon refrigerant include fluorinated straight-chain or branched-chain olefins and fluorinated cyclic olefins.

[0086] The linear or branched chain olefin is preferably a linear or branched chain olefin having a carbon number of 2 to 6. Examples of fluorinated products of the linear olefin include ethylene having 1 to 3 fluorine atoms introduced therein, propene having 1 to 5 fluorine atoms introduced therein, butene having 1 to 7 fluorine atoms introduced therein, pentene having 1 to 9 fluorine atoms introduced therein, and hexene having 1 to 11 fluorine atoms introduced therein.

[0087] The cyclic olefin is preferably a cyclic olefin having a hydrocarbon ring with 4 to 6 carbon atoms. Examples of the fluorinated cyclic olefin include cyclobutene having 1 to 5 fluorine atoms introduced therein, cyclopentene having 1 to 7 fluorine atoms introduced therein, and cyclohexene having 1 to 9 fluorine atoms introduced therein.

[0088] The HC-based refrigerant is preferably a hydrocarbon having 1 to 8 carbon atoms, more preferably a hydrocarbon having 1 to 5 carbon atoms, and even more preferably a hydrocarbon having 3 to 5 carbon atoms. If the hydrocarbon has 8 or less carbon atoms, the boiling point of the refrigerant will not be too high, making it preferable as a refrigerant. Specific examples of the HC-based refrigerant include methane, ethane, ethylene, propane, cyclopropane, propylene, n-butane, isobutane, 2-methylbutane, n-pentane, isopentane, cyclopentane, isobutane, and normal butane.

[0089] The content of the refrigerant in the composition for refrigerators is, for example, 1 to 99 mass %, and preferably 2 to 95 mass %, relative to the total amount of the composition for refrigerators.

[0090] (Other Components) The refrigerating machine composition may contain other components in addition to the above-mentioned components. Examples of the other components include known or commonly used components that may be contained in conventional refrigerating machine oils, refrigerants, and refrigerating machine compositions. Examples of the other components include antioxidants, oiliness improvers, extreme pressure agents, acid scavengers, oxygen scavengers, metal deactivators, rust inhibitors, and antifoaming agents. When the refrigerating machine composition contains the other additives, the content of the other additives is preferably 0.05 to 5 mass%, more preferably 0.1 to 3 mass%, and even more preferably 0.2 to 2 mass%, relative to the total amount of the refrigerating machine composition. Only one of the other components may be used, or two or more of them may be used.

[0091] As the extreme pressure agent, known or commonly used extreme pressure agents that may be contained in conventional refrigerator compositions can be used, among which phosphorus-based extreme pressure agents, metal salts of carboxylic acids, and sulfur-based extreme pressure agents are preferred.

[0092] Examples of the phosphorus-based extreme pressure agents include phosphate esters, acid phosphate esters, phosphites, acid phosphites, and amine salts thereof. Specific examples of the phosphorus-based extreme pressure agents include tricresyl phosphate (TCP), trithiophenyl phosphate, tri(nonylphenyl)phosphite, dioleylhydrogen phosphite, and 2-ethylhexyldiphenyl phosphite.

[0093] Examples of the metal salts of carboxylic acids include metal salts of carboxylic acids having 3 to 60 carbon atoms (preferably 3 to 30 carbon atoms). Of these, metal salts of fatty acids having 12 to 30 carbon atoms and metal salts of dicarboxylic acids having 3 to 30 carbon atoms are preferred. The metal constituting the metal salts is preferably an alkali metal or alkaline earth metal, more preferably an alkali metal.

[0094] Examples of the sulfur-based extreme pressure agents include sulfurized fats and oils, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dihydrocarbyl polysulfides, thiocarbamates, thioterpenes, and dialkylthiodipropionates.

[0095] The content of the extreme pressure agent is preferably 0.0005 to 3 mass %, more preferably 0.002 to 2 mass %, relative to the total amount of the refrigerator composition, from the viewpoint of further reducing the friction coefficient and the wear amount.

[0096] (Composition for refrigerator) The haze value of the composition for refrigerator is preferably 5 or less, more preferably 3 or less, and even more preferably 1 or less. The composition for refrigerator has excellent dispersibility of nanodiamond particles, so that a composition for refrigerator with the above haze value can be obtained. The haze value can be measured according to JIS K 7136.

[0097] The coefficient of friction of the composition for a refrigerator when used as a lubricant in a ring-on-disk friction test under conditions of a surface pressure of 2 MPa and a speed of 1.5 m / s is preferably 0.08 or less, more preferably 0.05 or less, even more preferably 0.04 or less, and particularly preferably 0.03 or less. When the coefficient of friction is 0.08 or less, the coefficient of friction and the amount of wear of the sliding member tend to be further reduced.

[0098] The above-mentioned refrigerating machine composition can be obtained, for example, by mixing a refrigerating machine oil (A) containing refrigerating machine oil and nanodiamond particles dispersed in the above-mentioned refrigerating machine oil with a refrigerant (B).In addition, the refrigerating machine oil (A) and the refrigerant (B) can be combined to form a refrigerating machine composition kit, and the refrigerating machine composition can be prepared by mixing before use.

[0099] [Refrigerant composition kit] The refrigerant composition kit includes at least a refrigerant oil (A) and a refrigerant (B) (the refrigerant). The refrigerant oil (A) includes a base oil, nanodiamond particles dispersed in the base oil, and the dispersant. Examples of the base oil include those exemplified and described as the refrigerant oil contained in the refrigerant composition. The refrigerant oil (A) and the refrigerant (B) may each contain the components exemplified and described as other components described above.

[0100] The content of the base oil in the refrigerating machine oil (A) is not particularly limited, but is, for example, 80 to 98 mass %, preferably 90 to 95 mass %, based on the total amount of the refrigerating machine oil (A).

[0101] In the refrigerating machine oil (A), the nanodiamond particles are preferably dispersed on the order of nanometers. The average dispersed particle diameter (D50, median diameter) of the nanodiamond particles in the refrigerating machine oil (A) is preferably 2 to 240 nm, more preferably 4 to 200 nm, more preferably 5 to 100 nm, even more preferably 10 to 70 nm, and particularly preferably 12 to 40 nm. The average dispersed particle diameter can be measured by dynamic light scattering.

[0102] The content of nanodiamond particles in the refrigerating machine oil (A) is preferably 1 to 10,000 ppm by mass, more preferably 5 to 1,000 ppm by mass, and even more preferably 10 to 500 ppm by mass, relative to the total amount of the refrigerating machine oil (A). A content of 1 ppm by mass or more can more sufficiently reduce the coefficient of friction between sliding members in the refrigerator. When the content is within the above range, the dispersibility of the nanodiamond particles is improved. Furthermore, the refrigerating machine oil (A) may be a concentrated liquid that is diluted before use to reduce the content of nanodiamond particles. Therefore, the content may be greater than 10,000 ppm by mass or greater than 2% by mass. Because the refrigerating machine oil (A) has excellent dispersibility of nanodiamond particles, even when the content exceeds 10,000 ppm by mass, the nanodiamond particles can be dispersed with a small dispersed particle size while reducing the amount of dispersant added. The content is preferably 10% by mass or less, from the viewpoint of better dispersibility of the nanodiamond particles.

[0103] The content of the nanodiamond particles can be calculated from the absorbance at 350 nm.In addition, when the content of surface-modified nanodiamond particles is low concentration (for example, 2000 mass ppm or less), the compound that surface-modifies the nanodiamond particles can be detected by high-frequency inductively coupled plasma atomic emission spectroscopy (ICP atomic emission spectroscopy), and the content can be determined based on the detected amount.

[0104] The content of the dispersant in the refrigerating machine oil (A) is preferably 100 to 10,000 parts by mass, more preferably 200 to 5,000 parts by mass, and even more preferably 400 to 2,000 parts by mass, per 100 parts by mass of the total amount of nanodiamond particles.

[0105] The content of the extreme pressure agent is preferably 0.001 to 5 mass%, more preferably 0.005 to 3 mass%, based on the total amount of the refrigerating machine oil (A), from the viewpoint of further reducing the friction coefficient and the amount of wear.

[0106] The refrigerating machine oil (A) preferably has a friction coefficient of 0.08 or less, more preferably 0.07 or less, even more preferably 0.05 or less, and particularly preferably 0.03 or less, when used as a lubricant in a ring-on-disk friction test under conditions of a surface pressure of 2 MPa and a speed of 1.5 m / s. When the friction coefficient is 0.08 or less, the friction coefficient and wear amount of the sliding member tend to be further reduced.

[0107] Refrigerating machine oil (A) can be produced, for example, by mixing nanodiamond particles, a dispersant, and, if necessary, other components into the base oil to disperse the nanodiamond particles. In addition, refrigerating machine oil (A) using surface-modified nanodiamond particles can also be produced through a process (modification process) in which a compound to be surface-treated is reacted with the nanodiamond particles in the base oil. In this case, the solvent used in the modification process can be used as the base oil in the refrigerating machine oil (A). In addition, the solvent used in the modification process can be used as the base oil in the refrigerating machine oil (A) as is, or solvent exchange can be performed after the modification process.

[0108] In the above-mentioned modification step, when the nanodiamond particles contain nanodiamond particle aggregates formed by the aggregation of nanodiamond particles to form secondary particles, it is preferable to carry out the reaction between the surface treatment compound and the nanodiamond particles while crushing or dispersing the nanodiamond particles. This allows the nanodiamond particle aggregates to be crushed into primary particles, the surfaces of the nanodiamond primary particles to be modified, and the dispersibility of the nanodiamond particles in the refrigerating machine oil (A) to be improved.

[0109] Examples of methods for crushing or dispersing nanodiamond particles include methods using a high shear mixer, a high shear mixer, a homomixer, a ball mill, a bead mill, a high-pressure homogenizer, an ultrasonic homogenizer, a colloid mill, a jet mill, etc. Among these, ultrasonic treatment in the presence of crushing media (e.g., zirconia beads, etc.) is preferred.

[0110] The refrigerating machine composition can be produced by, for example, mixing the refrigerating machine oil (A) prepared as described above with the refrigerant (B) while maintaining the nanodiamond particles dispersed. In this way, the refrigerating machine oil (A) in which the nanodiamond particles are dispersed in the base oil and the refrigerating machine composition can be obtained. In addition, the refrigerating machine composition kit can be obtained by combining the refrigerating machine oil (A) and the refrigerant (B).

[0111] The above-mentioned refrigerator composition and the refrigerator composition kit refrigerator composition are compositions used in refrigerators. Use of the refrigerator composition in a refrigerator can reduce the coefficient of friction between sliding members within the refrigerator. Furthermore, when used in a refrigerator, a refrigerator composition containing a refrigerant is required to promote lubrication between sliding members under pressure at reduced pressure, and is required to have sufficient lubrication performance under conditions more severe than atmospheric conditions. In contrast, the refrigerator composition of the present disclosure can reduce the coefficient of friction between sliding members even when used under such severe conditions. Furthermore, reducing the viscosity of the refrigerator composition used as a lubricant can be considered to reduce the coefficient of friction between sliding members within a refrigerator, but reducing the viscosity tends to make the sliding members more susceptible to seizure. In contrast, the refrigerator composition of the present disclosure can suppress seizure of sliding members and reduce the amount of wear of the sliding members.

[0112] The refrigerator includes, for example, a compressor, a condenser, an expansion mechanism (such as an expansion valve), an evaporator, and a dryer. Therefore, the refrigerator composition can be used in such various devices that the refrigerator may include. The refrigerator composition is used, for example, as a lubricant for lubricating sliding parts provided in a compressor or the like. In this case, the refrigerator composition can be used as a working fluid for a refrigerator.

[0113] The lubricant may be an initial break-in lubricant used to form a low-friction surface (break-in surface) at the beginning of use of a refrigerator having a sliding member. The initial break-in lubricant, for example, smooths out unevenness on the surface of the sliding member or forms a modified surface. After the break-in surface is formed, the initial break-in lubricant is removed by washing or the like, and sliding is performed using a lubricant that performs the main lubrication. Here, the lubricant that performs the main lubrication refers to a lubricant that is not removed and remains in the sliding part during operation of the sliding member (during use of the refrigerator). Note that the initial break-in lubricant can be used as the main lubricant after the formation of the break-in surface, either as is or after being removed and then resupplied to the sliding part. For example, the refrigerating machine oil (A) described below may be used as the initial break-in lubricant.

[0114] Examples of the refrigeration machine include air conditioners, refrigerators, vending machines, showcases, refrigeration systems, hot water supply systems, heating systems, etc. Examples of the air conditioners include car air conditioners such as open-type car air conditioners and electric car air conditioners, gas heat pump (GHP) air conditioners, and indoor air conditioners.

[0115] Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. Each configuration and combination thereof in each embodiment is an example, and addition, omission, substitution, and other modifications of configurations are possible as appropriate within the scope of the present disclosure. Furthermore, each invention according to this disclosure is not limited by the embodiments or the following examples, but is limited only by the scope of the claims.

[0116] Hereinafter, one embodiment of the present disclosure will be described in more detail based on examples.

[0117] Example 1 (Production of surface nanodiamond particles) First, a nanodiamond production process was carried out by detonation. In this process, a formed explosive with an electric detonator attached was placed inside a pressure-resistant container for detonation, and the container was sealed. The container was made of iron and had a volume of 15 m 3As the explosive, 0.50 kg of a mixture of TNT and RDX was used. The mass ratio of TNT to RDX (TNT / RDX) in this explosive was 50 / 50. Next, an electric detonator was detonated to detonate the explosive in the container (generation of nanodiamonds by detonation method). Next, the container and its interior were allowed to cool by leaving it at room temperature for 24 hours. After this cooling, the nanodiamond crude product (including the aggregates of nanodiamond particles and soot generated by the detonation method) adhering to the inner wall of the container was scraped off with a spatula, and the nanodiamond crude product was recovered.

[0118] The crude nanodiamond product obtained by repeating the above-described production process multiple times was then subjected to an acid treatment process. Specifically, 200 g of the crude nanodiamond product was added to 6 L of 10% by mass hydrochloric acid to obtain a slurry, which was then heated under reflux at atmospheric pressure for 1 hour. The heating temperature in this acid treatment was 85-100°C. Next, after cooling, the solids (including nanodiamond aggregates and soot) were washed with water by decantation. The solids were repeatedly washed with water by decantation until the pH of the precipitated liquid reached 2 from the low pH side.

[0119] Next, an oxidation treatment step was carried out. Specifically, 6 L of 98% by mass sulfuric acid and 1 L of 69% by mass nitric acid were added to the precipitate liquid (containing nanodiamond aggregates) obtained through decantation after the acid treatment to form a slurry, and this slurry was then heat-treated for 48 hours under reflux at atmospheric pressure. The heating temperature in this oxidation treatment was 140-160°C. Next, after cooling, the solids (including nanodiamond aggregates) were washed with water by decantation. The supernatant liquid was colored at the beginning of the washing, and the solids were repeatedly washed with water by decantation until the supernatant liquid became visually transparent.

[0120] Next, 1000 mL of the nanodiamond-containing liquid obtained after the above-mentioned water washing treatment was spray-dried using a spray dryer (trade name "Spray Dryer B-290", manufactured by Nippon Buchi Co., Ltd.) (drying step), thereby obtaining 50 g of nanodiamond powder.

[0121] 0.3 g of nanodiamond particles obtained in the drying process was weighed into a reaction vessel, and 13.5 g of MIBK and 1.2 g of hexyltrimethoxysilane as a silane compound were added and stirred for 10 minutes.

[0122] After stirring, 36 g of zirconia beads (Tosoh Corporation, registered trademark "YTZ", diameter 30 μm) were added. After addition, the mixture was cooled in ice water and ultrasonicated for 20 hours using an ultrasonic disperser (model "UP-400s", Hielscher) with the tip of the ultrasonic disperser's transducer immersed in the solution in the reaction vessel, resulting in a reaction between the nanodiamond particles and the silane compound. Initially, the mixture was gray, but the particle size gradually decreased and the dispersion improved, eventually becoming a uniform, black liquid. This is thought to be due to the nanodiamond particles gradually being disintegrated (disintegrated) from the nanodiamond particle aggregates, and the silane compound acting on and bonding to the dissociated nanodiamond particles, resulting in the dispersion and stabilization of the surface-modified nanodiamond particles in MIBK. In this way, a nanodiamond dispersion (MIBK dispersion) was obtained.

[0123] (Preparation of nanodiamond-dispersed refrigerator composition) A dispersant (trade name "BYK-9077", manufactured by BYK-Chemie) was added to the surface-modified nanodiamond dispersion obtained above and stirred, after which the MIBK was distilled off using a rotary evaporator, and refrigerant oil (trade name "Daphne Hermetic Oil FVC68D", manufactured by Idemitsu Kosan Co., Ltd.) was added. In this way, a nanodiamond-dispersed refrigerator composition (nanodiamond concentration: 10 ppm by mass, dispersant concentration: 100 ppm by mass) was prepared. The nanodiamond concentration was determined from the absorbance at 350 nm.

[0124] Example 2 (Preparation of nanodiamond-dispersed refrigerator composition) After adding a dispersant (trade name "Ajisper PN411", manufactured by Ajinomoto Fine-Techno Co., Ltd.) to the surface-modified nanodiamond dispersion liquid prepared in Example 1 and stirring, MIBK was distilled off using a rotary evaporator, and refrigerant oil (trade name "Daphne Hermetic Oil FVC68D", manufactured by Idemitsu Kosan Co., Ltd.) was added. In this way, a nanodiamond-dispersed refrigerator composition (nanodiamond concentration: 10 mass ppm, dispersant concentration: 50 mass ppm) was prepared. The nanodiamond concentration was determined from the absorbance at 350 nm.

[0125] Comparative Example 1 Trade name "Daphne Hermetic Oil FVC68D" (manufactured by Idemitsu Kosan Co., Ltd.) was used as a refrigerating machine oil.

[0126] <Evaluation> Each of the nanodiamond-dispersed refrigerator compositions obtained in the examples and comparative examples was evaluated as follows.

[0127] (1) Ring-on-disk friction test (in air) Each of the nanodiamond-dispersed refrigerator compositions obtained in Example 1 and Comparative Example 1 was used as a lubricating oil sample. The friction test was conducted using a ring-on-disk thrust friction and wear tester (disk contact surface method) (device name "AT-800", manufactured by A&D Co., Ltd.). The test specimens, the ring and disk, were a cast iron ring with an outer diameter of 44 mm and an inner diameter of 32 mm at the contact surface, and a cast iron disk with a diameter of 50 mm at the contact surface, both of which were subjected to flat polishing (Ra = 0.3 μm or less). At the start of the test, the disk was immersed in the refrigerator composition, and the test was conducted at room temperature.

[0128] The comparison results of Example 1 and Comparative Example 1 are shown in Figures 1 to 3 (friction coefficients) and Figure 4 (wear volume). Figure 1 shows the graph at a sliding speed of 0.5 m / s, Figure 2 shows the graph at a sliding speed of 1.5 m / s, and Figure 3 shows the graph at a sliding speed of 2.5 m / s. In the figures, black squares (■) indicate the Example (with nanodiamond particles), and black circles (●) indicate the Comparative Example (without nanodiamond particles).

[0129] (2) Ring-on-Disk Friction Test (in Refrigerant) The nanodiamond-dispersed refrigeration compositions obtained in Examples 1 and 2 and Comparative Example 1 were used as lubricant samples. The friction tests were conducted using a ring-on-disk thrust friction and wear tester (disk contact type) (device name "AT-800" manufactured by A&D Co., Ltd.). The test specimens, the ring and disk, were cast iron rings with an outer diameter of 44 mm and an inner diameter of 32 mm at the contact surface, and cast iron disks with a diameter of 50 mm at the contact surface, both of which were polished to a flat surface (Ra = 0.3 μm or less). At the start of the test, 300 mL of the lubricant sample was poured onto the sliding surface of the disk, and 0.2 kg of refrigerant was poured into the disks under reduced pressure using a vacuum pump. The test was then conducted under pressurized conditions. The refrigerant used in the comparison tests for Example 1 and Comparative Example 1 was R32, and the refrigerant used in the comparison tests for Example 2 and Comparative Example 1 was R410A.

[0130] The results of comparing Example 1 and Comparative Example 1 are shown in Figures 5 to 7 (friction coefficient) and Figure 8 (wear amount), while the results of comparing Example 2 and Comparative Example 1 are shown in Figures 9 to 11 (friction coefficient) and Figure 12 (wear amount). Figures 5 and 9 show graphs at a sliding velocity of 0.5 m / s, Figures 6 and 10 show graphs at a sliding velocity of 1.5 m / s, and Figures 7 and 11 show graphs at a sliding velocity of 2.5 m / s. In the figures, black squares (■) indicate Examples (with nanodiamond particles), and black circles (●) indicate Comparative Examples (without nanodiamond particles).

[0131] The test conditions for the ring-on-disk friction tests (1) and (2) above were a stepwise change of the sliding velocity from 0.5 m / s, 1.5 m / s, and 2.5 m / s, while the inter-face contact pressure at each sliding velocity was changed from 0.5 MPa to 1.0 MPa, 2.0 MPa, 3.0 MPa, 4.0 MPa, and 5.0 MPa. Specifically, the sliding velocity was first maintained at 0.5 m / s, while the inter-face contact pressure was changed from 0.5 MPa to 1.0 MPa, 2.0 MPa, 3.0 MPa, 4.0 MPa, and 5.0 MPa. The sliding velocity was then changed to 1.5 m / s, while the inter-face contact pressure was returned to 0.5 MPa. Similarly, the inter-face contact pressure was changed stepwise to 5.0 MPa while maintaining the sliding velocity. The sliding velocity was then changed to 2.5 m / s, and the inter-face contact pressure was returned to 0.5 MPa. Similarly, while maintaining the sliding velocity, the inter-face contact pressure was changed stepwise up to 5.0 MPa, with each step held for 5 minutes.

[0132] The amount of wear of the ring and the disc was determined as the difference in mass between the ring and the disc before and after the ring-on-disc test.

[0133] As shown in Figures 1-3, 5-7, and 9-11, when a refrigerator composition containing dispersed nanodiamond particles was used as a lubricant (Example), the coefficient of friction tended to be lower than when a refrigerator composition containing no nanodiamond particles was used as a lubricant (Comparative Example). Furthermore, the coefficient of friction was particularly reduced in the range where the interfacial contact pressure was 4 MPa or less. Furthermore, as shown in Figures 4, 8, and 12, when a refrigerator composition containing dispersed nanodiamond particles was used as a lubricant (Example), the amount of wear was either equivalent or significantly reduced compared to when a refrigerator composition containing no nanodiamond particles was used as a lubricant (Comparative Example).

[0134] Variations of the present invention are described below. [Appendix 1] A refrigerating composition comprising a refrigerating oil, nanodiamond particles dispersed in the refrigerating oil, and a dispersant. [Appendix 2] The refrigerating composition according to Appendices 1 or 2, wherein the refrigerating oil comprises polyvinyl ethers, polyol esters, polyalkylene glycols, alkylated aromatic hydrocarbon compounds, or mineral oil. [Appendix 3] The refrigerating composition according to Appendices 1 or 2, wherein the dispersant comprises a dispersant (I) having a mass average molecular weight of 500 or more and an amine value of 15 mgKOH / g or more, and / or a fatty acid ester-based dispersant (II). [Appendix 4] The refrigerating composition according to Appendices 3, wherein the dispersant (I) has a mass average molecular weight of 650 or more (preferably 950 or more). [Appendix 5] The refrigerating composition according to Appendices 3 or 4, wherein the dispersant (I) has a mass average molecular weight of 20,000 or less (preferably 10,000 or less). [Appendix 6] The refrigerator composition according to any one of Appendices 3 to 5, wherein the dispersant (I) has an amine value of 18 mgKOH / g or more (preferably 20 mgKOH / g or more, more preferably 30 mgKOH / g or more). [Appendix 7] The refrigerator composition according to any one of Appendices 3 to 6, wherein the dispersant (I) has an amine value of 100 mgKOH / g or less (preferably 90 mgKOH / g or less, more preferably 60 mgKOH / g or less). [Appendix 8] The refrigerator composition according to any one of Appendices 3 to 7, wherein the dispersant (I) is one or more compounds selected from a compound having a polyalkylene glycol monoalkyl ether-derived structure (particularly a polyethylene glycol monoalkyl ether-derived structure or a polypropylene glycol monoalkyl ether-derived structure), a compound having a carbamate structure, and a compound having a polycaprolactone-derived structure. [Appendix 9] The composition for refrigerators according to any one of Appendices 3 to 8, wherein the acid value of the dispersant (II) is 40 mgKOH / g or less (preferably 35 mgKOH / g or less, more preferably 30 mgKOH / g or less, even more preferably 20 mgKOH / g or less, particularly preferably 6 mgKOH / g or less). [Appendix 10] The composition for refrigerators according to any one of Appendices 3 to 9, wherein the acid value of the dispersant (II) is 0.1 mgKOH / g or more (preferably 0.3 mgKOH / g or more, more preferably 0.5 mgKOH / g or more).[Appendix 11] The composition for a refrigerator according to any one of Appendices 3 to 10, wherein the amine value of the dispersant (II) is 5 mgKOH / g or less (preferably 1 mgKOH / g or less, more preferably 0.5 mgKOH / g or less, even more preferably 0.1 mgKOH / g or less, and particularly preferably 0 mgKOH / g). [Appendix 12] The composition for a refrigerator according to any one of Appendices 3 to 11, wherein the average molecular weight Mp of the dispersant (II) is 300 or more (preferably 1000 or more (e.g., 1000 to 100,000), more preferably 3000 or more (e.g., 3000 to 10,000)). [Appendix 13] The composition for a refrigerator according to any one of Appendices 3 to 12, wherein the dispersant (II) has a mass loss rate of 30% or less (preferably 25% or less, more preferably 20% or less, and even more preferably 15% or less) when maintained in an air atmosphere at 200°C for 180 minutes. [Appendix 14] The refrigerator composition according to any one of Appendices 3 to 13, wherein the dispersant (II) has an acidic functional group. [Appendix 15] The refrigerator composition according to any one of Appendices 3 to 14, wherein the dispersant (II) is a higher fatty acid ester dispersant. [Appendix 16] The refrigerating machine oil has an SP value of 6.0 to 12.0 (cal / cm). 3 ) 1 / 2 The refrigerator composition according to any one of Appendices 1 to 15, wherein the nanodiamond particles are surface-modified nanodiamonds having a surface-modifying group containing an organic group that surface-modifies the nanodiamond particles. [Appendix 18] The refrigerator composition according to Appendices 17, wherein the organic group is an organic group having 4 or more carbon atoms (e.g., 4 to 25), 6 or more carbon atoms (e.g., 6 to 22), or 8 or more carbon atoms (e.g., 8 to 20). [Appendix 19] The refrigerator composition according to Appendices 17 or 18, wherein the surface-modifying group is a group represented by the following formula (I): -X-R (I) [In formula (I), X represents a linking group, and the bond extending to the left from X is bonded to the nanodiamond. R represents a monovalent organic group, and the atom bonded to X is a carbon atom. [Appendix 20] The composition for a refrigerator according to Appendices 19, wherein the group represented by formula (I) is a group represented by the following formula (1) or a group containing a polyglycerin chain: -X 1 -R 1 (1) [In formula (1), X1 represents —O—Si—, —Si—, —NH—, —O—, —O—C(═O)—, —C(═O)—O—, —NH—C(═O)—, —C(═O)—NH—, or —S—; X 1 The bond extending to the left from R binds to the nanodiamond. 1 represents a substituted or unsubstituted monovalent hydrocarbon group, and X 1 The atom bonded to R is a carbon atom. 1The refrigerator composition according to any one of Appendices 1 to 22, wherein the number of carbon atoms in the formula (I) is 4 to 25 (preferably 6 to 22, more preferably 8 to 20). [Appendix 22] The refrigerator composition according to any one of Appendices 1 to 21, wherein the nanodiamond particles are dispersed on the order of nanometers. [Appendix 23] The refrigerator composition according to any one of Appendices 1 to 22, wherein the average dispersed particle size (D50, median diameter) of the nanodiamond particles in the refrigerator composition is 2 to 240 nm (preferably 4 to 200 nm, more preferably 5 to 100 nm, even more preferably 6 to 70 nm, even more preferably 10 to 60 nm, even more preferably 10 to 40 nm, and particularly preferably 11 to 30 nm). [Appendix 24] The refrigerating composition according to any one of Appendices 1 to 23, wherein the content of nanodiamond particles in the refrigerating composition is 1 to 10,000 ppm by mass (preferably 5 to 1,000 ppm by mass, more preferably 10 to 500 ppm by mass) relative to the total amount of refrigerating oil. [Appendix 25] The refrigerating composition according to any one of Appendices 1 to 24, wherein the content of dispersant in the refrigerating composition is 100 to 10,000 parts by mass (preferably 200 to 5,000 parts by mass, more preferably 400 to 2,000 parts by mass) relative to 100 parts by mass of the total amount of nanodiamond particles. [Appendix 26] The refrigerating composition according to any one of Appendices 1 to 25, further comprising an extreme pressure agent (preferably a phosphorus-based extreme pressure agent, a metal salt of a carboxylic acid, a sulfur-based extreme pressure agent, more preferably a phosphorus-based extreme pressure agent). [Appendix 27] The refrigerator composition according to Appendices 26, wherein the content of the extreme pressure agent is 0.0005 to 3 mass% (preferably 0.002 to 2 mass%) relative to the total amount of the refrigerator composition. [Appendix 28] The refrigerator composition according to any one of Appendices 1 to 27, wherein the haze value is 5 or less (preferably 3 or less, more preferably 1 or less). [Appendix 29] The refrigerator composition according to any one of Appendices 1 to 28, wherein the coefficient of friction when used as a lubricant in a ring-on-disk friction test under conditions of a surface pressure of 2 MPa and a speed of 1.5 m / s is 0.08 or less. [Appendix 30] The refrigerator composition according to any one of Appendices 1 to 29, which is for use in a compressor of a refrigerator. [Appendix 31] The refrigerator composition according to any one of Appendices 1 to 30, wherein the refrigerator is an air-conditioning device.

[0135] [Appendix 32] A refrigerator composition kit comprising a refrigerating machine oil (A) containing a base oil and nanodiamond particles dispersed in the base oil, and a refrigerant (B). [Appendix 33] The refrigerator composition kit according to Appendices 32, wherein the content of the base oil in the refrigerating machine oil (A) is 80 to 98 mass% (preferably 90 to 95 mass%) relative to the total amount of the refrigerating machine oil (A). [Appendix 34] The refrigerator composition kit according to Appendices 32 or 33, wherein the refrigerating machine oil contains polyvinyl ethers, polyol esters, polyalkylene glycols, alkylated aromatic hydrocarbon compounds, or mineral oil. [Appendix 35] The refrigerator composition kit according to any one of Appendices 32 to 34, wherein the dispersant contains a dispersant (I) having a mass average molecular weight of 500 or more and an amine value of 15 mgKOH / g or more, and / or a fatty acid ester-based dispersant (II). [Appendix 36] A refrigerator composition kit according to Appendices 35, in which the dispersant (I) has a mass average molecular weight of 650 or more (preferably 950 or more). [Appendix 37] A refrigerator composition kit according to Appendices 35 or 36, in which the dispersant (I) has a mass average molecular weight of 20,000 or less (preferably 10,000 or less). [Appendix 38] A refrigerator composition kit according to any one of Appendices 35 to 37, in which the dispersant (I) has an amine value of 18 mgKOH / g or more (preferably 20 mgKOH / g or more, more preferably 30 mgKOH / g or more). [Appendix 39] A refrigerator composition kit according to any one of Appendices 35 to 38, in which the dispersant (I) has an amine value of 100 mgKOH / g or less (preferably 90 mgKOH / g or less, more preferably 60 mgKOH / g or less). [Appendix 40] The composition kit for a refrigerator according to any one of Appendices 35 to 39, wherein the dispersant (I) is one or more compounds selected from a compound having a structure derived from a polyalkylene glycol monoalkyl ether (particularly, a structure derived from a polyethylene glycol monoalkyl ether or a structure derived from a polypropylene glycol monoalkyl ether), a compound having a carbamate structure, and a compound having a structure derived from polycaprolactone.[Appendix 41] The refrigerator composition kit according to any one of Appendices 35 to 40, wherein the acid value of the dispersant (II) is 40 mgKOH / g or less (preferably 35 mgKOH / g or less, more preferably 30 mgKOH / g or less, even more preferably 20 mgKOH / g or less, and particularly preferably 6 mgKOH / g or less). [Appendix 42] The refrigerator composition kit according to any one of Appendices 35 to 41, wherein the acid value of the dispersant (II) is 0.1 mgKOH / g or more (preferably 0.3 mgKOH / g or more, more preferably 0.5 mgKOH / g or more). [Appendix 43] The refrigerator composition kit according to any one of Appendices 35 to 42, wherein the amine value of the dispersant (II) is 5 mgKOH / g or less (preferably 1 mgKOH / g or less, more preferably 0.5 mgKOH / g or less, even more preferably 0.1 mgKOH / g or less, particularly preferably 0 mgKOH / g). [Appendix 44] The refrigerator composition kit according to any one of Appendices 35 to 43, wherein the average molecular weight Mp of the dispersant (II) is 300 or more (preferably 1,000 or more (e.g., 1,000 to 100,000), more preferably 3,000 or more (e.g., 3,000 to 10,000)). [Appendix 45] A refrigerator composition kit according to any one of Appendices 35 to 44, wherein the dispersant (II) has a mass loss rate of 30% or less (preferably 25% or less, more preferably 20% or less, and even more preferably 15% or less) when maintained in an air atmosphere at a temperature of 200°C for 180 minutes. [Appendix 46] A refrigerator composition kit according to any one of Appendices 35 to 45, wherein the dispersant (II) has an acidic functional group. [Appendix 47] A refrigerator composition kit according to any one of Appendices 35 to 46, wherein the dispersant (II) is a higher fatty acid ester dispersant. [Appendix 48] The refrigerating machine oil has an SP value of 6.0 to 12.0 (cal / cm). 3 ) 1 / 2The refrigerator composition kit according to any one of Appendices 32 to 47, wherein the nanodiamond particles are surface-modified nanodiamonds having a surface-modifying group containing an organic group that surface-modifies the nanodiamond particles. [Appendix 50] The refrigerator composition kit according to Appendices 49, wherein the organic group is an organic group having 4 or more carbon atoms (e.g., 4 to 25), 6 or more carbon atoms (e.g., 6 to 22), or 8 or more carbon atoms (e.g., 8 to 20). [Appendix 51] The refrigerator composition kit according to Appendices 49 or 50, wherein the surface-modifying group is a group represented by the following formula (I): -X-R (I) [In formula (I), X represents a linking group, and the bond extending to the left from X is bonded to the nanodiamond. R represents a monovalent organic group, and the atom bonded to X is a carbon atom. [Appendix 52] The composition kit for a refrigerator according to Appendices 51, wherein the group represented by formula (I) is a group represented by the following formula (1) or a group containing a polyglycerin chain: -X 1 -R 1 (1) [In formula (1), X 1 represents —O—Si—, —Si—, —NH—, —O—, —O—C(═O)—, —C(═O)—O—, —NH—C(═O)—, —C(═O)—NH—, or —S—; X 1 The bond extending to the left from R binds to the nanodiamond. 1 represents a substituted or unsubstituted monovalent hydrocarbon group, and X 1 The atom bonded to R is a carbon atom. 1The number of carbon atoms in the formula (A) is 4 to 25 (preferably 6 to 22, more preferably 8 to 20). [Appendix 54] The refrigerator composition kit according to any one of Appendices 32 to 53, wherein the nanodiamond particles are dispersed in the refrigerator oil (A) on the order of nanometers. [Appendix 55] The refrigerator composition kit according to any one of Appendices 32 to 54, wherein the average dispersed particle size (D50, median diameter) of the nanodiamond particles in the refrigerator oil (A) is 2 to 240 nm (preferably 4 to 200 nm, more preferably 5 to 100 nm, even more preferably 10 to 70 nm, and particularly preferably 12 to 40 nm). [Appendix 56] The refrigerator composition kit according to any one of Appendices 32 to 55, wherein the content of nanodiamond particles in the refrigerator oil (A) is 1 to 10,000 ppm by mass (preferably 5 to 1,000 ppm by mass, more preferably 10 to 500 ppm by mass) relative to the total amount of the refrigerator oil (A). [Appendix 57] The refrigerator composition kit according to any one of Appendices 32 to 56, wherein the content of dispersant in the refrigerator oil (A) is 100 to 10,000 parts by mass (preferably 200 to 5,000 parts by mass, more preferably 400 to 2,000 parts by mass) relative to 100 parts by mass of the total amount of nanodiamond particles. [Appendix 58] The refrigerator composition kit according to any one of Appendices 32 to 57, wherein the refrigerator oil (A) contains an extreme pressure agent. [Appendix 59] The refrigerating machine composition kit according to Appendices 58, wherein the content of the extreme pressure agent is 0.001 to 5 mass% (preferably 0.005 to 3 mass%) relative to the total amount of the refrigerating machine oil (A). [Appendix 60] The refrigerating machine composition kit according to any one of Appendices 32 to 53, wherein the refrigerating machine oil (A) has a friction coefficient of 0.08 or less when used as a lubricant in a ring-on-disk friction test under conditions of a surface pressure of 2 MPa and a speed of 1.5 m / s. [Appendix 61] The refrigerating machine composition kit according to any one of Appendices 32 to 60, which is for use in a compressor of a refrigerating machine. [Appendix 62] The refrigerating machine composition kit according to any one of Appendices 32 to 61, wherein the refrigerating machine is an air-conditioning equipment.

[0136] The composition for refrigerators of the present disclosure can be used in refrigerators and air conditioning equipment that uses refrigerators.

Claims

1. A composition for a refrigerator comprising a refrigerator oil, nanodiamond particles dispersed in the refrigerator oil, and a dispersant.

2. 2. The refrigeration composition according to claim 1, wherein the refrigeration oil comprises polyvinyl ethers, polyol esters, polyalkylene glycols, alkylated aromatic hydrocarbon compounds, or mineral oils.

3. 3. The composition for a refrigerator according to claim 1, wherein the dispersant comprises a dispersant (I) having a mass average molecular weight of 500 or more and an amine value of 15 mgKOH / g or more, and / or a fatty acid ester-based dispersant (II).

4. The SP value of the refrigerating machine oil is 6.0 to 12.0 (cal / cm ３ ) １／２ The composition for refrigerators according to claim 1 or 2,

5. 3. The composition for refrigerators according to claim 1, which has a friction coefficient of 0.08 or less when used as a lubricant in a ring-on-disk friction test under conditions of a surface pressure of 2 MPa and a speed of 1.5 m / s.

6. The composition for a refrigerator according to claim 1 or 2, which is used for a compressor of a refrigerator.

7. The composition for a refrigerator according to claim 1 or 2, wherein the refrigerator is an air-conditioning device.

8. A refrigeration composition kit comprising a refrigeration oil (A) containing a base oil and nanodiamond particles dispersed in the base oil, and a refrigerant (B).

9. 9. The refrigeration composition kit according to claim 8, wherein the refrigeration oil (A) has a friction coefficient of 0.08 or less when used as a lubricant in a ring-on-disk friction test under conditions of a surface pressure of 2 MPa and a speed of 1.5 m / s.