JP7587372B2 - Lubricant fillers and lubricant compositions - Google Patents

Description

The present invention relates to a lubricating filler and a lubricating composition.

Many machines are equipped with parts that slide against each other while rubbing against each other (sliding parts). In such machines, low friction is usually required in the sliding parts. To reduce friction in such sliding parts, various lubricating compositions have been used in the past.

2. Description of the Related Art Lubricating compositions containing solid lubricants such as graphite, polytetrafluoroethylene (PTFE), and molybdenum disulfide (MoS ₂ ) are known.

However, conventional solid lubricants have limitations in reducing the dynamic friction coefficient when used in a lubricating composition. Specifically, currently widely used solid lubricants, when used in a lubricating composition, exhibit a dynamic friction coefficient of only 0.04 under friction evaluation conditions as described below (see, for example, Non-Patent Document 1). For this reason, there is a demand for solid lubricants that, when used in a lubricating composition, exhibit a dynamic friction coefficient that is even lower than 0.04.

Recently, in light of the trend toward resource and energy conservation, the applicant has reported on lubricating fillers such as lightweight carbon-coated inorganic particles and hollow carbon microparticles that can be mass-produced at low cost (Patent Document 1), and has mentioned fillers that are lightweight and have excellent lubricity, excellent electrical conductivity, excellent thermal conductivity, and excellent oxidation resistance as examples of the industrial applicability of this lubricating filler ("Industrial Applicability" in Patent Document 1).

International Publication No. 2020/054833

New Edition "Solid Lubrication Handbook" Edited by Solid Lubrication Research Group of the Japanese Society of Tribologists, 1st Edition, March 2, 2010

The object of the present invention is to provide a lubricating filler that, when made into a lubricating composition, can exhibit a dynamic friction coefficient at a level even lower than 0.04. Also, the object of the present invention is to provide a lubricating composition containing such a lubricating filler.

The applicant, referring to the lubricating filler described in Patent Document 1, investigated whether it is possible to design a solid lubricant that, when made into a lubricating composition, can exhibit a dynamic friction coefficient even lower than 0.04. Then, when designing a lubricating filler in which the surfaces of inorganic particles are coated with a carbon material, it was found that a significantly low dynamic friction coefficient can be exhibited by controlling the average particle diameter (D90, the maximum diameter value that includes 90% of all particles counting from the smallest) of the inorganic particles to a specific size, and further found that a dynamic friction coefficient even lower than 0.04 can be exhibited.

The lubricating filler according to an embodiment of the present invention comprises:
A lubricating filler in which the surface of an inorganic particle is coated with a carbon material,
The inorganic particles have an average particle size of 0.5 μm or more.

In one embodiment, the lubricating filler is
When a dispersion obtained by dispersing the dispersion in a dispersion medium to a concentration of 20% by mass is subjected to a friction test, the average dynamic friction coefficient μ(20,1000) after 1000 reciprocating slides is less than 0.04.

In one embodiment, the lubricating filler has an average dynamic friction coefficient μ(5,1000) of less than 0.04 after 1,000 reciprocating slides when the dispersion is dispersed in a dispersion medium to a concentration of 5% by mass and subjected to a friction test.

The lubricating composition according to an embodiment of the present invention includes a lubricating filler according to an embodiment of the present invention.

According to the present invention, it is possible to provide a lubricating filler that, when made into a lubricating composition, can exhibit a dynamic friction coefficient at a level even lower than 0.04. It is also possible to provide a lubricating composition that contains such a lubricating filler.

FIG. 2 is a schematic cross-sectional view showing an organic-inorganic composite that can be produced during the production of a lubricating filler according to an embodiment of the present invention. FIG. 1 is a schematic cross-sectional view showing a core-shell particle as an example of a lubricating filler according to an embodiment of the present invention. FIG. 2 is a graph showing the measurement results of the relationship between the number of reciprocating slides and the average dynamic friction coefficient in the friction test in Examples 1 and 2. FIG. 13 is a graph showing the measurement results of the relationship between the number of reciprocating slides and the average dynamic friction coefficient in the friction test in Examples 3 and 4. FIG. 1 is a graph showing the relationship between the number of reciprocating slides and the average dynamic friction coefficient in the friction test in Examples 5, 6, and 7. FIG. 1 is a graph showing the relationship between the number of reciprocating slides and the average dynamic friction coefficient in the friction test in Comparative Examples 1 and 2. FIG. 13 is a graph showing the measurement results of the relationship between the number of reciprocating slides and the average dynamic friction coefficient in the friction test in Example 8. FIG. 13 is a graph showing the measurement results of the relationship between the number of reciprocating slides and the average dynamic friction coefficient in the friction test in Example 9. FIG. 13 is a graph showing the measurement results of the relationship between the number of reciprocating slides and the average dynamic friction coefficient in the friction test in Example 10. FIG. 13 is a graph showing the measurement results of the relationship between the number of reciprocating slides and the average dynamic friction coefficient in the friction test in Example 11. FIG. 13 is a graph showing the measurement results of the relationship between the number of reciprocating slides and the average dynamic friction coefficient in the friction test in Example 12. FIG. 1 is a graph showing the measurement results of the relationship between the number of reciprocating slides and the average dynamic friction coefficient in the friction test in Reference Example 1.

In this specification, the "carbon material" contained in the lubricating filler may be referred to as the "carbon material portion." Also, in this specification, the "inorganic particles" contained in the lubricating filler may be referred to as the "inorganic particle portion."

<<<<1. Lubricating filler>>>
The lubricating filler according to an embodiment of the present invention is a lubricating filler in which the surfaces of inorganic particles are coated with a carbon material, and the inorganic particles have an average particle size of 0.5 μm or more.

The effect of the lubricating filler according to the embodiment of the present invention is largely due to rolling friction, so if the particles have a particle size distribution, it is believed that the larger components of each particle size contribute more to rolling friction. For this reason, D90, which is the maximum diameter value that includes 90% of all particles, counting from the smallest, is used as the average particle diameter for the lubricating filler according to the embodiment of the present invention.

In the lubricating filler according to the embodiment of the present invention, the average particle size (D90) of the inorganic particles is 0.5 μm or more, preferably 1.0 μm or more, more preferably 1.5 μm or more, even more preferably 2.0 μm or more, and particularly preferably 2.3 μm or more. The upper limit of the average particle size (D90) of the inorganic particles is preferably 10.0 μm or less, more preferably 5.0 μm or less, even more preferably 3.0 μm or less, and particularly preferably 2.7 μm or less. If the average particle size (D90) of the inorganic particles is controlled within the above-mentioned specific range, the lubricating filler according to the embodiment of the present invention can exhibit unprecedentedly excellent low friction that exceeds the limit value of the dynamic friction coefficient that can be expressed when a conventional solid lubricant, typically graphite, polytetrafluoroethylene (PTFE), molybdenum disulfide (MoS ₂ ), etc. is used as a lubricating composition (graphite is 0.06 level, PTFE is 0.04 level, MoS ₂ is 0.04 level). If the average particle size (D90) of the inorganic particles is outside the above range, there is a risk that the kinetic friction coefficient achieved will be equal to or less than that achieved when the lubricating composition is made of a conventional solid lubricant, typically graphite, polytetrafluoroethylene (PTFE), molybdenum disulfide (MoS ₂ ), etc.

The average particle size (D90) of inorganic particles is the average particle size (D90) in the volume-based particle size distribution, and is preferably measured by a laser diffraction scattering method.

The lubricating filler according to the embodiment of the present invention is preferably a spherical particle. Spherical particles can be more effective due to rolling friction. As the spherical particles, rounded particles and true spherical particles are particularly preferred.

The lubricating filler according to the embodiment of the present invention can exhibit very excellent lubricity when used in a lubricating composition. Specifically, it can exhibit a lower level of dynamic friction coefficient than the level of 0.04, which is generally known as the limit value of the dynamic friction coefficient that can be exhibited when a conventional solid lubricant is used in a lubricating composition.

The lubricating filler according to an embodiment of the present invention has an average dynamic friction coefficient μ(20,1000) of less than 0.04 after 1000 reciprocating slides when the dispersion, which is dispersed in a dispersion medium to a concentration of 20% by mass, is subjected to a friction test. Details of the friction test will be described later.

Considering that the reciprocating sliding was performed at a high frequency of 1000 times, the fact that the above μ(20,1000) is less than 0.04 means that an unprecedentedly excellent low friction can be achieved that exceeds the limit value of the dynamic friction coefficient that can be achieved when conventional solid lubricants, typically graphite, polytetrafluoroethylene (PTFE), molybdenum disulfide ( _MoS2 ), etc. are used as the lubricating composition (graphite is at the 0.06 level, PTFE is at the 0.04 level, and _MoS2 is at the 0.04 level).

The above μ(20,1000) is preferably 0.035 or less, more preferably 0.03 or less, even more preferably 0.025 or less, even more preferably 0.02 or less, even more preferably 0.015 or less, particularly preferably 0.010 or less, and most preferably 0.005 or less. The lower limit of the above μ(20,1000) is preferably as low as possible, and in reality, it is 0.001 or more.

The lubricating filler according to the embodiment of the present invention has an average dynamic friction coefficient μ(5,1000) at 1000 reciprocating slides when the dispersion is dispersed in a dispersion medium to a concentration of 5% by mass and subjected to a friction test, which is preferably less than 0.04, more preferably 0.035 or less, even more preferably 0.03 or less, even more preferably 0.025 or less, even more preferably 0.02 or less, particularly preferably 0.015 or less, and most preferably 0.010 or less. The lower limit of the above μ(5,1000) is preferably as low as possible, and is practically 0.001 or more. Considering that the dispersion concentration is as low as 5 mass % and that the reciprocating sliding is performed at a high frequency of 1000 times, the fact that the above μ (5,1000) is within the above range means that an unprecedentedly excellent low friction can be achieved that exceeds the limit value of the dynamic friction coefficient that can be achieved when a conventional solid lubricant, typically graphite, polytetrafluoroethylene (PTFE), molybdenum disulfide (MoS ₂ ), etc. is used as the lubricating composition (graphite is at the 0.06 level, PTFE is at the 0.04 level, and MoS ₂ is at the 0.04 level).

The lubricating filler according to the embodiment of the present invention has an average dynamic friction coefficient μ(0.5,1000) at 1000 reciprocating slides when the dispersion is dispersed in a dispersion medium to a concentration of 0.5% by mass and subjected to a friction test, which is preferably less than 0.04, more preferably 0.035 or less, even more preferably 0.03 or less, even more preferably 0.025 or less, even more preferably 0.02 or less, particularly preferably 0.015 or less, and most preferably 0.010 or less. The lower limit of the above μ(0.5,1000) is preferably as low as possible, and in reality, it is 0.001 or more. Considering that the dispersion concentration is an ultra-low concentration of 0.5 mass % and that the reciprocating sliding is performed at a high number of times, 1000 times, the fact that the above μ (0.5, 1000) is within the above range means that an unprecedented and even superior low friction can be achieved that exceeds the limit value of the dynamic friction coefficient that can be achieved when a conventional solid lubricant, typically graphite, polytetrafluoroethylene (PTFE), molybdenum disulfide (MoS ₂ ), etc. is used as the lubricating composition (graphite is at the 0.06 level, PTFE is at the 0.04 level, and MoS ₂ is at the 0.04 level).

The above friction test conditions are merely one of the suitable conditions for using the lubricating filler according to the embodiment of the present invention. The lubricating filler according to the embodiment of the present invention can also be used suitably under other conditions.

The lubricating filler according to the embodiment of the present invention exhibits high lubricating properties by itself, but it is also preferable to use it in a liquid state such as a dispersion medium or in a semi-liquid state such as a grease. In that case, it is preferable to use a dispersion medium to make it into a semi-liquid state.

As the dispersion medium, any suitable dispersion medium can be used as long as it can disperse the lubricating filler according to the embodiment of the present invention well, and does not impair the effects of the present invention.

The harder the material of the substrate and contacts, the better their wear resistance, but by using the lubricating filler according to an embodiment of the present invention, relatively soft metals can also be used. In addition to metals, ceramics can also be used as the base material.

It is believed that the lighter and lower the load and pressure, the smaller the coefficient of friction and the better the wear resistance, but if the lubricating filler of the present invention is used, it can be used suitably even under higher pressure conditions. Specifically, the load and pressure are preferably 1 kPa or more, and more preferably 1 MPa or more.

The lubricating filler according to an embodiment of the present invention is made of inorganic particles whose surfaces are coated with a carbon material.

In accordance with an embodiment of the present invention, the thickness of the carbon material layer of the lubricating filler in which the surface of the inorganic particle is coated with a carbon material is preferably 0.3 nm or more, more preferably 0.5 nm or more. In order not to impair the properties of the inorganic particle, the thickness of the carbon material layer is preferably 10 nm or less, more preferably 5 nm or less.

In the lubricating filler according to an embodiment of the present invention, any appropriate method may be used to coat the surfaces of the inorganic particles with a carbon material as long as it does not impair the effects of the present invention.

The lubricating filler according to the embodiment of the present invention is preferably the lubricating filler of the following two embodiments. However, the lubricating filler according to the embodiment of the present invention may be one other than the following two embodiments, as long as it does not impair the effects of the present invention.

(Preferred embodiment 1)
A lubricant filler obtained by a method including a heating step (I) of heating a composition containing a compound (A) that undergoes a condensation reaction between identical molecules and/or different molecules when heated, and inorganic particles, and a carbon material removal step of removing a portion of the carbon material produced by heating the compound (A) after the heating step (I), and, if necessary, a heating step (II) of further heating after the carbon material removal step.

(Preferred embodiment 2)
A lubricating filler obtained by a method including a mixing step (I) of mixing a soluble carbon material that is soluble in a solvent (S) with inorganic particles in the solvent (S).

The lubricating filler according to the present invention will be described below in two preferred embodiments: Preferred embodiment 1 and Preferred embodiment 2.

<<1-1. Preferred embodiment 1 of lubricating filler>>
A preferred embodiment 1 of the lubricant filler is a lubricant filler obtained by a method including a heating step (I) of heating a composition containing inorganic particles and a compound (A) that undergoes a condensation reaction between identical molecules and/or different molecules when heated, and a carbon material removal step of removing a portion of the carbon material generated by heating the compound (A) after the heating step (I), and, if necessary, a heating step (II) of further heating after the carbon material removal step.

In the heating step (I) in which a composition containing inorganic particles and a compound (A) that undergoes a condensation reaction between the same molecules and/or different molecules by heating is heated, the compound (A) in the composition is heated to become a carbon material, and an organic-inorganic composite in which a plurality of inorganic particles are dispersed in the carbon material as a matrix is formed.

1, the heating step (I) produces an organic-inorganic composite 100 in which a plurality of inorganic particles 20 are dispersed in a carbon material 10 as a matrix, and at the interface between the carbon material 10 and the inorganic particles 20, a carbon material region (carbon material bonded region) 30 is typically formed by the carbon material forming a bond with a functional group present on the surface of the inorganic particles 20. In this case, for example, when the carbon material is soluble in a solvent, a carbon material removal step is performed in which the organic-inorganic composite 100 is treated with a solvent that dissolves the carbon material, and a heating step (II) is further performed as necessary, thereby obtaining a core-shell particle (core part: inorganic particle, shell part: carbon material bonded region) 200 in which the surface of the inorganic particle 20 is coated with a carbon material bonded region (region that is not dissolved by the solvent) 30, as shown in FIG. 2. The core-shell particle 200 obtained when the heating step (II) is performed is a highly carbonized core-shell particle.

The carbon material 10 as the matrix in FIG. 1 and the carbon material bonding region (region that is not dissolved by the solvent) 30 in FIG. 2 correspond to the carbon material in the lubricating filler according to an embodiment of the present invention. In terms of being able to more effectively express the effects of the present invention, the lubricating filler according to an embodiment of the present invention is preferably a core-shell particle 200 (including the case of a highly carbonized core-shell particle) shown in FIG. 2, and in this case, the carbon material bonding region (region that is not dissolved by the solvent) 30 present on the surface of the inorganic particle 20 corresponds to the carbon material in the lubricating filler according to an embodiment of the present invention.

≪1-1-1. Inorganic particles≫
As the inorganic particles, any appropriate inorganic particles can be adopted as long as the effects of the present invention are not impaired.

There may be only one type of inorganic particles, or two or more types.

The inorganic particles are preferably at least one selected from the group consisting of inorganic oxide particles, inorganic nitride particles, inorganic sulfide particles, inorganic carbide particles, and insoluble salt particles.

<1-1-1-1. Inorganic oxide particles>
The inorganic oxide particles may be of one type or of two or more types. Examples of the use of two or more types of inorganic oxide particles include the case where two or more types of inorganic oxide particles are simply used in combination (mixed, etc.) and the case where two or more types of inorganic oxide particles are bound to each other.

The decomposition temperature of the inorganic oxide particles is preferably 800°C or higher, more preferably 850°C or higher, even more preferably 900°C or higher, and particularly preferably 950°C or higher, in order to better demonstrate the effects of the present invention.

Inorganic oxide particles include not only metal particles that are entirely oxidized, but also metal particles that are partially oxidized, preferably metal particles that have at least a portion of their surface oxidized. This is because metals can generally be partially, preferably at least a portion of their surface, oxidized in the presence of oxygen.

Metals that can be used in inorganic oxide particles are preferably metals that are easily oxidized, such as magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), indium (In), gallium (Ga), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), cadmium (Cd), aluminum (Al), tin (Sn), lanthanum (La), yttrium (Y), cerium (Ce), and silicon (silicon, Si), and more preferably copper (Cu), aluminum (Al), and silicon (silicon, Si). Such metals are easily oxidized, and are either entirely oxidized or partially, preferably at least partially, on the surface.

Specific examples of inorganic oxide particles include:
(1) Metal particles that are entirely oxidized;
(2) Metal particles having a part thereof oxidized (preferably, metal particles having at least a part of their surface oxidized);
(3) Composite oxide particles having two or more constituent metal elements;
(4) So-called solid solution oxide particles, which are oxides (also called single metal oxides) or composite oxides each consisting of one type of metal element, to which a different element (metal element, non-metal element other than oxygen such as nitrogen or fluorine) is further dissolved in solid solution.
etc.

Examples of the above (1) "metal particles entirely oxidized" or (2) "metal particles partially oxidized (preferably metal particles at least partially oxidized on the surface)" include magnesium oxide, calcium oxide, strontium oxide, barium oxide, titanium oxide, zirconium oxide, hafnium oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, indium oxide, gallium oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, zinc oxide, cadmium oxide, aluminum oxide, tin oxide, lanthanum oxide, yttrium oxide, cerium oxide, and silicon oxide, and preferably magnesium oxide, titanium oxide (titania), aluminum oxide (alumina), and silicon oxide (silica).

As the above (3) "composite oxide particles having two or more constituent metal elements," any appropriate composite oxide particles may be used as long as the effects of the present invention are not impaired. Representative examples of such composite oxide particles include oxide particles containing two or more metals, such as composite oxide particles with a perovskite structure and composite oxide particles with a spinel structure.

The perovskite structure composite oxide particles are typically oxide particles represented by the formula ABO ₃ (A and B represent different elements), and examples of such oxides include perovskite (perovskite, CaTiO 3 ), barium titanate _{(BaTiO 3 ), strontium titanate (SrTiO 3 ), lead zirconate titanate (Pb(Zr,Ti)O 3 ) , barium} zirconate (BaZrO ₃ ), and lithium niobate (LiNbO ₃ ).

Examples of the double oxide particles having a spinel structure include spinel (MgAl ₂ O ₄ ) particles, lithium titanate (LiTi ₂ O ₄ ) particles, and chrysoberyl (BeAl ₂ O ₄ ) particles.

As for the above (4) "so-called solid solution oxide particles in which a heterogeneous element (metal element, nonmetal element other than oxygen, such as nitrogen or fluorine) is further dissolved in an oxide (also called a single metal oxide) or a composite oxide consisting of one type of constituent metal element," any appropriate solid solution oxide particle may be adopted within a range that does not impair the effects of the present invention. A representative example of such solid solution oxide particles is a particle in which a heterogeneous metal element and/or a nonmetal element other than oxygen (such as nitrogen or fluorine) is dissolved in a single metal oxide or a composite oxide.

In terms of being able to more effectively exhibit the effects of the present invention, the inorganic oxide particles are preferably inorganic oxide particles having a functional group on the surface. Examples of such functional groups include hydroxyl functional groups such as M-OH; oxygen functional groups containing ether functional groups such as M-O-M; nitrogen functional groups containing amine functional groups such as M-NH ₂ and M-NH-M; sulfur functional groups containing thiol functional groups such as M-SH and M-S-M; and silicon functional groups, boron functional groups, phosphorus functional groups, and the like (M conceptually indicates the object to which the functional group is bonded, and indicates any appropriate object to which the functional group can be bonded, such as the inorganic oxide particles themselves, or metal elements and organic groups constituting the inorganic oxide particles). These functional groups can be easily formed by surface-treating the inorganic oxide particles with various compounds. If inorganic oxide particles having functional groups on the surface are used as the inorganic oxide particles, the functional groups present on the surface of the inorganic oxide particles can easily form bonds with the carbon material, and therefore inorganic oxide particles coated with the carbon material can be obtained. The inorganic oxide particles are preferably inorganic oxide particles having oxygen functional groups on the surface.

The inorganic oxide particles having a functional group on the surface are preferably at least one selected from the group consisting of silica particles, alumina particles, titania particles, magnesium oxide particles, polyacid particles, metal particles having at least a portion of their surface oxidized, composite oxide particles, and solid solution oxide particles. By adopting at least one selected from the group consisting of silica particles, alumina particles, titania particles, magnesium oxide particles, polyacid particles, metal particles having at least a portion of their surface oxidized, composite oxide particles, and solid solution oxide particles as the inorganic oxide particles having a functional group on the surface, the functional groups present on the surface of the inorganic oxide particles can more easily form bonds with the carbon material.

Polyacids that make up the polyacid particles include isopolyacids and heteropolyacids.

As the isopolyacid, any suitable isopolyacid may be used as long as it does not impair the effects of the present invention. Examples of such isopolyacids include inorganic acids and salts thereof that are mainly composed of inorganic elements such as molybdenum, vanadium, tungsten, niobium, titanium, tantalum, chromium, manganese, rhenium, iron, ruthenium, cobalt, nickel, palladium, platinum, copper, silver, gold, tin, titanium, zirconium, rhodium, iridium, osmium, and zinc, and representative examples include molybdic acid, vanadic acid, tungstic acid, niobic acid, titanic acid, and tantalic acid.

As the heteropolyacid, any appropriate heteropolyacid may be used as long as it does not impair the effects of the present invention. Examples of such heteropolyacids include isopolyacids or metal salts thereof into which a heteroatom has been introduced. Examples of heteroatoms include oxygen, sulfur, phosphorus, ammonium, potassium, sodium, and silicon. The heteropolyacid may be a hydrate.

Specific examples of heteropolyacids include tungsten-based heteropolyacids obtained by introducing a heteroatom into a tungsten-containing isopolyacid, and molybdenum-based heteropolyacids obtained by introducing a heteroatom into a molybdenum-containing isopolyacid.

Examples of tungsten-based heteropolyacids include phosphotungstic acid, silicotungstic acid, cobalt tungstic acid, germanotungstic acid, borotungstic acid, phosphovanadotungstic acid, and phosphotungstomolybdic acid.

Examples of molybdenum-based heteropolyacids include phosphomolybdic acid, silicomolybdic acid, and phosphovanadomolybdic acid.

<1-1-1-2. Inorganic nitride particles>
As the inorganic nitride particles, any suitable inorganic nitride particles can be adopted as long as the effect of the present invention is not impaired. Examples of such inorganic nitride particles include boron nitride particles, carbon nitride particles, aluminum nitride particles, and gallium nitride particles, and preferably boron nitride particles and aluminum nitride particles.

The inorganic nitride particles may be of one type or of two or more types.

In terms of being able to further exert the effects of the present invention, the inorganic nitride particles are preferably inorganic nitride particles having functional groups on the surface. Examples of such functional groups include hydroxyl functional groups such as M-OH; oxygen functional groups containing ether functional groups such as M-O-M; nitrogen functional groups containing amine functional groups such as M-NH ₂ and M-NH-M; sulfur functional groups containing thiol functional groups such as M-SH and M-S-M; and silicon functional groups, boron functional groups, phosphorus functional groups, and the like (M conceptually indicates the object to which the functional group is bonded, and indicates any appropriate object to which the functional group can be bonded, such as the inorganic nitride particles themselves, or metal elements and organic groups constituting the inorganic nitride particles). These functional groups can be easily formed by surface-treating the inorganic nitride particles with various compounds. If inorganic nitride particles having functional groups on the surface are adopted as the inorganic nitride particles, the functional groups present on the surface of the inorganic nitride particles can easily form bonds with the carbon material, so that inorganic nitride particles coated with the carbon material can be obtained.

<1-1-1-3. Inorganic sulfide particles>
As the inorganic sulfide particles, any suitable inorganic sulfide may be used as long as it does not impair the effects of the present invention. Examples of such inorganic sulfide particles include copper sulfide particles, zinc sulfide particles, and sulfide particles. Cadmium particles and the like.

The inorganic sulfide particles may be of one type or of two or more types.

In terms of being able to further exert the effects of the present invention, the inorganic sulfide particles are preferably inorganic sulfide particles having functional groups on the surface. Examples of such functional groups include hydroxyl functional groups such as M-OH; oxygen functional groups containing ether functional groups such as M-O-M; nitrogen functional groups containing amine functional groups such as M-NH ₂ and M-NH-M; sulfur functional groups containing thiol functional groups such as M-SH and M-S-M; and other silicon functional groups, boron functional groups, phosphorus functional groups, and the like (M conceptually indicates the object to which the functional group is bonded, and indicates any appropriate object to which the functional group can be bonded, such as the inorganic sulfide particles themselves, or metal elements and organic groups constituting the inorganic sulfide particles). These functional groups can be easily formed by surface-treating the inorganic sulfide particles with various compounds. If inorganic sulfide particles having functional groups on the surface are used as the inorganic sulfide particles, the functional groups present on the surface of the inorganic sulfide particles can easily form bonds with the carbon material, so that inorganic sulfide particles coated with the carbon material can be obtained.

<1-1-1-4. Inorganic carbide particles>
As the inorganic carbide particles, any suitable inorganic carbide particles can be used as long as the effects of the present invention are not impaired. Examples of such inorganic carbide particles include silicon carbide particles, tungsten carbide particles, and calcium carbide particles.

The inorganic carbide particles may be of one type or of two or more types.

In terms of being able to more effectively exhibit the effects of the present invention, the inorganic carbide particles are preferably inorganic carbide particles having functional groups on the surface. Examples of such functional groups include hydroxyl functional groups such as M-OH; oxygen functional groups containing ether functional groups such as M-O-M; nitrogen functional groups containing amine functional groups such as M-NH ₂ and M-NH-M; sulfur functional groups containing thiol functional groups such as M-SH and M-S-M; and silicon functional groups, boron functional groups, phosphorus functional groups, and the like (M conceptually indicates the object to which the functional group is bonded, and indicates any appropriate object to which the functional group can be bonded, such as the inorganic carbide particles themselves, or metal elements and organic groups constituting the inorganic carbide particles). These functional groups can be easily formed by surface-treating the inorganic carbide particles with various compounds. If inorganic carbide particles having functional groups on the surface are used as the inorganic carbide particles, the functional groups present on the surfaces of the inorganic carbide particles can easily form bonds with the carbon material, and therefore inorganic carbide particles coated with the carbon material can be obtained.

<1-1-1-5. Insoluble salt particles>

As the insoluble salt particles, any suitable insoluble salt particles may be used as long as the effects of the present invention are not impaired. Such insoluble salt particles are preferably metal-containing salt particles that are insoluble in organic solvents, such as metal phosphate particles, such as lithium iron phosphate particles, and metal sulfate particles, and are preferably lithium iron phosphate particles.

The insoluble salt particles may be of only one type or of two or more types.

≪1-1-2. Organic-inorganic composite≫
In a preferred embodiment 1 of the lubricating filler, a heating step (I) is performed in which a composition containing a compound (A) that undergoes a condensation reaction between the same molecules and/or different molecules by heating and inorganic particles is heated to form the composition. The compound (A) in the matrix is heated to become a carbon material, which becomes an organic-inorganic composite in which a plurality of inorganic particles are dispersed in the carbon material as a matrix. The organic-inorganic composite contains a carbon material and inorganic particles.

The carbon material may be one type or two or more types.

There may be only one type of inorganic particles, or two or more types.

The heating temperature in the heating step (I) is preferably (T-150)°C or higher when the condensation reaction temperature of compound (A) is T°C.

In the heating step (I), a composition containing compound (A) and inorganic particles that undergoes a condensation reaction between the same molecules and/or different molecules by heating is heated. The compound (A) and inorganic particles are preferably 0.01% by mass to 1,000,000% by mass, more preferably 0.1% by mass to 100,000% by mass, and particularly preferably 1% by mass to 1,000% by mass, relative to 100% by mass of the inorganic substance. If the compound (A) and inorganic particles are within the above range, an organic-inorganic composite having a more precisely controlled structure can be produced more easily under milder conditions. The compounding ratio of these inorganic particles and compound (A) can be adjusted arbitrarily depending on the physical properties of the desired organic-inorganic composite. For example, by adjusting the compounding ratio of inorganic particles and compound (A), the physical properties and form (for example, solubility in a solvent, the shape of the carbon component or inorganic component (particulate or non-particulate), the size of the carbon component or inorganic component, etc.) of the obtained organic-inorganic composite can be controlled.

The composition containing inorganic particles and compound (A) that undergoes a condensation reaction between the same molecules and/or different molecules upon heating may contain any other appropriate components as long as they do not impair the effects of the present invention. Examples of such other components include a solvent, a catalyst, a base material, and a carrier.

The composition to be heated in the heating step (I) may be prepared by any suitable method as long as it does not impair the effects of the present invention. Examples of such methods include a method in which compound (A) and inorganic particles are mixed in a solid state by any suitable method (e.g., crushing, pulverization, etc.). Another example includes a method in which compound (A), inorganic particles, a solvent, and, if necessary, other components other than the solvent, are mixed by any suitable method (e.g., ultrasonic treatment, etc.), and the solvent is removed by any suitable method (e.g., vacuum drying). Crushing may also be performed as necessary.

The heating temperature in the heating step (I) is preferably (T-150)°C or higher, more preferably (T-150 to T+50)°C, even more preferably (T-130 to T+45)°C, even more preferably (T-100 to T+40)°C, particularly preferably (T-80 to T+35)°C, and most preferably (T-50 to T+30)°C, when the condensation reaction temperature of compound (A) is T°C. When producing an organic-inorganic composite, the reaction can proceed and carbonization can proceed from a relatively low temperature compared to the condensation reaction temperature of compound (A) because of the high catalytic ability of the inorganic particles and the high reactivity of the functional groups on the inorganic particles with the carbon material. By adjusting the heating temperature to the above range, an organic-inorganic composite having solubility in a solvent or an organic-inorganic composite with a more precisely controlled structure can be produced more easily under milder conditions.

The condensation reaction temperature of the compound (A) can be determined by TG-DTA analysis. Specifically, it is as follows.
(1) When one type of compound is used as compound (A), the TG-DTA analysis of compound (A) is performed in a nitrogen gas atmosphere by increasing the temperature from 40° C. at a temperature increase rate of 10° C./min, and the peak top temperature on the lowest temperature side of the DTA is determined as the condensation reaction temperature (T° C.) of compound (A).
(2) When a mixture of two or more compounds is used as compound (A), the mixture is subjected to TG-DTA analysis in a nitrogen gas atmosphere by increasing the temperature from 40° C. at a temperature increase rate of 10° C./min, and the peak top temperature on the lowest temperature side of the DTA is determined as the condensation reaction temperature (T° C.) of compound (A) (a mixture of two or more compounds).
(3) However, when the compound (A) as one type of compound or a mixture of two or more types of compounds contains impurities such as a solvent, moisture, or hydration water, the DTA peak (sometimes called the impurity peak) associated with the elimination of the impurity may be observed at a temperature lower than the condensation reaction temperature. In such a case, the above-mentioned impurity peak is ignored and the condensation reaction temperature of the compound (A) is determined. Usually, the above-mentioned impurity peak is ignored and the lowest DTA peak top temperature is determined as the condensation reaction temperature of the compound (A).

The TG-DTA analysis can be carried out, for example, using the following apparatus and conditions.
Measurement device: Differential thermal and thermogravimetric simultaneous measurement device (TG/DTA6200, manufactured by Seiko Instruments Inc.)
The condensation reaction temperature of compound (A) can be determined as follows.
(1) When one type of compound is used as compound (A), the TG-DTA analysis of compound (A) is performed in a nitrogen gas atmosphere by increasing the temperature from 40° C. at a temperature increase rate of 10° C./min, and the peak top temperature on the lowest temperature side of the DTA is determined as the condensation reaction temperature (T° C.) of compound (A).
(2) When a mixture of two or more compounds is used as compound (A), the mixture is subjected to TG-DTA analysis in a nitrogen gas atmosphere by raising the temperature from 40° C. at a temperature increase rate of 10° C./min, and the peak top temperature on the lowest temperature side of the DTA can be determined as the condensation reaction temperature (T° C.) of compound (A) (a mixture of two or more compounds).
(3) However, when the compound (A) as one kind of compound or a mixture of two or more kinds of compounds contains impurities such as a solvent, moisture, water of hydration, etc., the DTA peak (sometimes called impurity peak) associated with the elimination of the impurity may be observed at a temperature lower than the condensation reaction temperature. In such a case, the above-mentioned impurity peak can be ignored and the condensation reaction temperature of the compound (A) can be determined. Specifically, the above-mentioned impurity peak can be ignored and the lowest DTA peak top temperature can be determined as the condensation reaction temperature of the compound (A).

The oxidation start temperature of the organic-inorganic composite can be estimated from the lowest DTA rise temperature when the temperature is increased from 40°C in an air atmosphere at a rate of 10°C/min.

The heating temperature in the heating step (I) is preferably 200°C to 500°C, more preferably 220°C to 400°C, even more preferably 230°C to 350°C, and most preferably 250°C to 300°C. By adjusting the heating temperature to within the above range, organic-inorganic composites that are soluble in solvents and organic-inorganic composites with more precisely controlled structures can be produced more easily under milder conditions. In particular, because the heating temperature in the heating step (I) is so low, organic-inorganic composites can be produced industrially under milder conditions.

The heating time in the heating step (I) is preferably 0.1 to 120 hours, more preferably 0.5 to 100 hours, even more preferably 1 to 50 hours, and most preferably 2 to 24 hours. By adjusting the heating time within the above range, an organic-inorganic composite that is soluble in a solvent or an organic-inorganic composite with a more precisely controlled structure can be produced more easily under milder conditions.

The content of the carbon material in the organic-inorganic composite is preferably 0.01% by mass to 99.99% by mass, and particularly preferably 0.1% by mass to 99.9% by mass, in terms of mass percentage. If the content of the carbon material in the organic-inorganic composite is within the above range, the organic-inorganic composite can be industrially produced under mild conditions, and the lubricating filler according to an embodiment of the present invention can be industrially produced using the organic-inorganic composite as a material.

The content of inorganic particles in the organic-inorganic composite is preferably 0.01% by mass to 99.99% by mass, and particularly preferably 0.1% by mass to 99.9% by mass, in terms of mass percentage. If the content of inorganic particles in the organic-inorganic composite is within the above range, the organic-inorganic composite can be industrially produced under mild conditions, and the lubricating filler according to an embodiment of the present invention can be industrially produced using the organic-inorganic composite as a material.

In the organic-inorganic composite, the ratio of all carbon-oxygen bonds, i.e., the total amount of C-O bonds and C=O bonds, to the total amount of all bonds, i.e., the total amount of C-C bonds, C=C bonds, C-H bonds, C-O bonds (including C-O bonds derived from alcohols, C-O bonds derived from ethers, C-O bonds derived from epoxy, etc.) and C=O bonds (including C=O bonds derived from carbonyls, C=O bonds derived from carboxyls, C=O bonds derived from esters, C=O bonds derived from lactones, etc.), as determined by C1s XPS analysis, is preferably 10% or more, more preferably 20% or more, and even more preferably 25% or more. The upper limit of the above ratio is preferably 35% or less. In an organic-inorganic composite, if the ratio of the total amount of C-O bonds and C=O bonds to the total amount of C-C bonds, C=C bonds, C-H bonds, C-O bonds, and C=O bonds according to C1sXPS analysis is within the above range, the organic-inorganic composite will have various physical properties such as solubility, unlike conventionally known simple carbon materials.

The C1sXPS analysis can be carried out, for example, using a photoelectron spectrometer (AXIS-ULTRA, manufactured by Shimadzu Corporation) under the following conditions.
Source: Mg (dual node)
Emission: 10mA
Anode: 10 kV
Analyzer: Pass Energy: 40
Measurement range: C1s: 296 to 270 eV
Number of integrations: 10 Analysis conditions: Peaks derived from C1s orbitals were separated for each functional group at the energies listed below, and the percentage was calculated from each area. The types of functional groups were separated into five peaks: (1) -COO-, lactone, and some ketones @ 288.3 eV, (2) C=O and epoxy groups @ 286.2 eV, (3) C-OH and C-O-C @ 285.6 eV, (4) 6-membered ring C=C @ 284.3 eV, and (5) C-C, C-H, and 5-membered ring C=C @ 283.6 eV. For the calculation of percentage, (4) and (5) may be calculated together. The % in the part related to C1s XPS means atomic %.

In the organic-inorganic composite, the ratio of the total amount of ether-derived C-O bonds (i.e., C-O-C bonds) and alcohol-derived C-O bonds (i.e., C-OH bonds) to the total amount of all carbon-oxygen bonds, i.e., C-O bonds (including alcohol-derived C-O bonds, ether-derived C-O bonds, epoxy-derived C-O bonds, etc.) and C=O bonds (including carbonyl-derived C=O bonds, carboxyl-derived C=O bonds, ester-derived C=O bonds, lactone-derived C=O bonds, etc.) as determined by C1s XPS analysis is preferably 50% or more, more preferably 60% or more, even more preferably 65% or more, particularly preferably 70% or more, and most preferably 75% or more. The upper limit of the above ratio is preferably 90% or less. In the organic-inorganic composite, if the ratio of the total amount of ether-derived C-O bonds and alcohol-derived C-O bonds to the total amount of C-O bonds and C=O bonds by C1sXPS analysis is within the above range, the organic-inorganic composite can increase the structural control rate of the carbon material portion and the structure can be controlled more precisely. The structural control rate indicates the ratio of bonds derived from the desired reaction to the total number of bonds. The total number of bonds corresponds to the total amount of C-O bonds and C=O bonds, and the bonds derived from the desired reaction correspond to the total amount of ether-derived C-O bonds and alcohol-derived C-O bonds. In other words, a high structural control rate means that there are many bonds derived from the desired reaction and few bonds derived from undesired reactions. The bonds derived from undesired reactions are C=O bonds derived from decomposition reactions, and the lower the structural control rate, the more the decomposition reaction is suppressed. It can be said that such an organic-inorganic composite has a more precisely controlled structure.

In the organic-inorganic composite, the ratio of the total amount of ether-derived C-O bonds (i.e., C-O-C bonds) and alcohol-derived C-O bonds (i.e., C-OH bonds) to the total amount of all bonds, i.e., C-C bonds, C-H bonds, C-O bonds (including alcohol-derived C-O bonds, ether-derived C-O bonds, epoxy-derived C-O bonds, etc.) and C=O bonds (including carbonyl-derived C=O bonds, carboxyl-derived C=O bonds, ester-derived C=O bonds, lactone-derived C=O bonds, etc.) according to C1s XPS analysis is preferably 15% or more, more preferably 17% or more, and even more preferably 20% or more. The upper limit of the above ratio is preferably 30% or less. In an organic-inorganic composite, if the ratio of the total amount of ether-derived C-O bonds (i.e., C-O-C bonds) and alcohol-derived C-O bonds (i.e., C-OH bonds) to the total amount of all bonds according to C1sXPS analysis is within the above range, the organic-inorganic composite can be said to be an organic-inorganic composite with a more precisely controlled structure.

It is particularly preferable that the organic-inorganic composite has a ratio of all carbon-oxygen bonds, i.e., the total amount of C-O bonds and C=O bonds, to the total amount of all bonds, i.e., C-C bonds, C=C bonds, C-H bonds, C-O bonds (including C-O bonds derived from alcohols, C-O bonds derived from ethers, C-O bonds derived from epoxy, etc.) and C=O bonds (including C=O bonds derived from carbonyls, C=O bonds derived from carboxyls, C=O bonds derived from esters, C=O bonds derived from lactones, etc.), as determined by C1s XPS analysis, within the above range, and In this embodiment, the ratio of the total amount of ether-derived C-O bonds (i.e., C-O-C bonds) and alcohol-derived C-O bonds (i.e., C-OH bonds) to the total amount of all carbon-oxygen bonds, i.e., C-O bonds (including alcohol-derived C-O bonds, ether-derived C-O bonds, epoxy-derived C-O bonds, etc.) and C=O bonds (including carbonyl-derived C=O bonds, carboxyl-derived C=O bonds, ester-derived C=O bonds, lactone-derived C=O bonds, etc.) as determined by C1sXPS analysis, is within the above range. In this embodiment, the organic-inorganic composite can further increase the solubility of the carbon material portion and can further increase the structural control rate of the carbon material portion. In addition, in this embodiment, the structure of the organic-inorganic composite can be controlled even more precisely.

It is particularly preferable that the organic-inorganic composite has a ratio of all carbon-oxygen bonds, i.e., the total amount of C-O bonds and C=O bonds, to the total amount of all bonds, i.e., C-C bonds, C=C bonds, C-H bonds, C-O bonds (including C-O bonds derived from alcohols, C-O bonds derived from ethers, C-O bonds derived from epoxy, etc.) and C=O bonds (including C=O bonds derived from carbonyls, C=O bonds derived from carboxyls, C=O bonds derived from esters, C=O bonds derived from lactones, etc.), as determined by C1s XPS analysis, within the above range, and In this embodiment, the ratio of the total amount of ether-derived C-O bonds (i.e., C-O-C bonds) and alcohol-derived C-O bonds (i.e., C-OH bonds) to the total amount of all bonds, i.e., C-C bonds, C-H bonds, C-O bonds (including alcohol-derived C-O bonds, ether-derived C-O bonds, epoxy-derived C-O bonds, etc.) and C=O bonds (including carbonyl-derived C=O bonds, carboxyl-derived C=O bonds, ester-derived C=O bonds, lactone-derived C=O bonds, etc.), based on analysis, is within the above range. In this embodiment, the organic-inorganic composite can further increase the solubility of the carbon material portion and can further increase the structural control rate of the carbon material portion. In addition, in this embodiment, the structure of the organic-inorganic composite can be controlled more precisely.

The organic-inorganic composite is most preferably such that the ratio of the total carbon-oxygen bonds, i.e., the total amount of C-O bonds and C=O bonds, to the total amount of all bonds, i.e., C-C bonds, C-H bonds, C-O bonds (including C-O bonds derived from alcohols, C-O bonds derived from ethers, C-O bonds derived from epoxy, etc.) and C=O bonds (including C=O bonds derived from carbonyls, C=O bonds derived from carboxyls, C=O bonds derived from esters, C=O bonds derived from lactones, etc.) as determined by C1s XPS analysis, is within the above range, and The ratio of the total amount of ether-derived C-O bonds (i.e., C-O-C bonds) and alcohol-derived C-O bonds (i.e., C-OH bonds) to the total amount of C-O bonds (including C-O bonds derived from alcohols, C-O bonds derived from ethers, C-O bonds derived from ethers, C-O bonds derived from epoxides, etc.) is within the above range, and the ratio of the total amount of ether-derived C-O bonds (i.e., C-O-C bonds) and alcohol-derived C-O bonds (i.e., C-OH bonds) to the total amount of all bonds, i.e., C-C bonds, C-H bonds, and C-O bonds (including C-O bonds derived from alcohols, C-O bonds derived from ethers, C-O bonds derived from epoxy, etc.) and C=O bonds (including C=O bonds derived from carbonyls, C=O bonds derived from carboxyls, C=O bonds derived from esters, C=O bonds derived from lactones, etc.) by C1sXPS analysis is within the above range. In such an embodiment, the organic-inorganic composite can further increase the solubility of the carbon material portion and further increase the structural control rate of the carbon material portion. Furthermore, in this embodiment, the structure of the organic-inorganic composite can be controlled even more precisely.

The organic-inorganic composite has an oxidation onset temperature, indicated by the DTA rise temperature when TG-DTA analysis is performed under air atmosphere with a temperature rise condition of 10°C/min from 40°C, of preferably 200°C or higher, more preferably 250°C or higher, and most preferably 300°C or higher. If the oxidation onset temperature indicated by the DTA rise temperature when TG-DTA analysis is performed under air atmosphere with a temperature rise condition of 10°C/min from 40°C for the organic-inorganic composite is within the above range, the organic-inorganic composite has high oxidation stability, that is, the structure is controlled and the skeletal structure is maintained, so that the oxidation resistance (decomposition resistance) is high. If the skeleton is cleaved to generate a C=O bond, the stability of the skeleton is reduced, and there is a risk of the oxidation resistance (decomposition resistance) being reduced.

The presence of carbon materials in organic-inorganic composites can be easily confirmed by X-ray photoelectron spectroscopy (C1sXPS).

The carbon material in the organic-inorganic composite preferably has a honeycomb structure (graphene structure) derived from benzene rings within its structure. The presence or absence of the graphene structure can be confirmed by Raman spectroscopy.

The Raman spectroscopic analysis can be performed, for example, using the following apparatus and conditions.
Measurement equipment: Raman microscope (JASCO NRS-3100)
Measurement conditions: 532 nm laser used, 20x objective lens, 1 second CCD capture time, 64 times total (resolution = 4 cm-1)

In addition, in Raman spectroscopy, the G' band and the D+D' band may appear overlapping, and the D+D' band may be analyzed as a broad peak with a shoulder. In this case, the inflection point of the shoulder peak is regarded as the peak of the G' band.

The carbon material in the organic-inorganic composite preferably contains 0.1 atomic % or less of metal components as impurities, based on 100 atomic % of carbon atoms, more preferably 0.01 atomic % or less, and particularly preferably substantially zero. The content of metal components as impurities in the carbon material in the organic-inorganic composite can be confirmed by X-ray fluorescence elemental analysis (XRF).

The carbon material in the organic-inorganic composite must contain carbon as an essential constituent element, and may contain elements other than carbon. Such elements other than carbon are preferably at least one element selected from oxygen, hydrogen, nitrogen, sulfur, fluorine, chlorine, bromine, and iodine, more preferably at least one element selected from oxygen, hydrogen, nitrogen, and sulfur, even more preferably at least one element selected from oxygen, hydrogen, and nitrogen, and particularly preferably at least one element selected from oxygen and hydrogen.

When the total amount of elements other than hydrogen among the elements constituting the carbon material in the organic-inorganic composite is taken as 100 atomic %, carbon is preferably 60 atomic % or more, more preferably 70 atomic % or more, and even more preferably 75 atomic % or more. When the total amount of elements other than hydrogen among the elements constituting the carbon material is taken as 100 atomic %, elements other than carbon are preferably 10 atomic % or more. The above ratio can be confirmed by quantifying the carbon material in the organic-inorganic composite by X-ray photoelectron spectroscopy (C1sXPS).

The carbon material in the organic-inorganic composite is preferably
(i) having peaks in the G band (generally in the range of 1550 cm ⁻¹ to 1650 cm ⁻¹ ) and the D band (generally in the range of 1300 cm ⁻¹ to 1400 cm ⁻¹ ) in a Raman spectrum obtained by Raman spectroscopy;
(ii) It contains a carbon-based compound that is soluble in a solvent.

The carbon material in the organic-inorganic composite exhibits a peak in the G band (generally in the range of 1550 cm ^-1 to 1650 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy. The fact that the carbon material has a peak in the G band (generally in the range of 1550 cm ^-1 to 1650 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy means that the carbon material has a graphene structure or a structure similar to a graphene structure. If the G band is strong and sharp, it can be said that the carbon material has a cleaner graphene structure or a structure similar to a graphene structure.

The carbon material in the organic-inorganic composite has a peak in the D band (generally in the range of 1300 cm ^-1 to 1400 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy. The carbon material having a structure derived from defects in the graphene structure shows a peak in the D band (generally in the range of 1300 cm ^-1 to 1400 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy. The fact that the carbon material has a peak in the D band (generally in the range of 1300 cm ^-1 to 1400 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy means that the carbon material has a structure derived from defects in the graphene structure or a structure similar to a structure derived from defects in the graphene structure. If the intensity of the D band is low, it can be said that the carbon material has a cleaner graphene structure or a structure similar to the graphene structure. The fact that the D band can be confirmed means that the carbon material in the organic-inorganic composite has a functional group, which can increase the solubility in the solvent.

The carbon material in the organic-inorganic composite shows a peak in the G' band (generally in the range of 2650 cm ^-1 to 2750 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy. The fact that the carbon material has a peak in the G' band (generally in the range of 2650 cm ^-1 to 2750 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy means that the carbon material has a graphene structure or a structure similar to the graphene structure. The intensity of the G' band is strongest when the graphene structure is one layer, and gradually decreases as the number of stacked graphene structures increases. Even if the intensity of the G' band gradually decreases as the number of stacked graphene structures increases, the peak can be observed. The presence of a peak in the G' band means that the carbon material in the organic-inorganic composite has a graphene structure or a structure similar to the graphene structure. The G' band is sometimes called a 2D band.

The carbon material in the organic-inorganic composite preferably has a peak in the D+D' band (generally in the range of 2800 cm ^-1 to 3000 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy. A carbon material having a structure derived from defects in a graphene structure exhibits a peak in the D+D' band (generally in the range of 2800 cm ^-1 to 3000 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy. A carbon material having a peak in the D+D' band (generally in the range of 2800 cm ^-1 to 3000 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy means that the carbon material has a structure derived from defects in the graphene structure or a structure similar to a structure derived from defects in the graphene structure. If the intensity of the D+D' band is low, it can be said that the carbon material has a cleaner graphene structure or a structure similar to a graphene structure. The D+D' band may also be called the D+G band. The fact that the D+D' band can be confirmed means that the carbon material in the organic-inorganic composite has a functional group, which can increase the solubility in the solvent.

When the carbon material in the organic-inorganic composite contains functional groups and has defects in part of the graphene structure, these defects can contribute to the solubility of the carbon material in a solvent.

As described above, unlike conventionally known carbon materials, the carbon material in the organic-inorganic composite has a graphene structure or a structure similar to a graphene structure, and the solubility of the carbon material in the organic-inorganic composite in a solvent is superior (for example, more components of the carbon material dissolve in the solvent, or more types of solvents in which the carbon material can be dissolved).

The molecular weight of the carbon-based compound contained in the carbon material in the organic-inorganic composite is preferably 1000 to 1300000, more preferably 5000 to 1000000, even more preferably 10000 to 700000, particularly preferably 15000 to 500000, and most preferably 20000 to 300000. If the molecular weight of the carbon-based compound contained in the carbon material in the organic-inorganic composite is within the above range, the solubility of the carbon material in the organic-inorganic composite in the solvent is more excellent in combination with the above characteristic (i) (for example, more components of the carbon material dissolve in the solvent, or more types of solvents in which the carbon material can be dissolved). If the molecular weight of the carbon-based compound contained in the carbon material in the organic-inorganic composite exceeds 1300000, the solubility of the carbon material in the organic-inorganic composite in the solvent may be deteriorated. If the molecular weight of the carbon-based compound contained in the carbon material in the organic-inorganic composite is less than 1000, the characteristics of the carbon material in the organic-inorganic composite may be weakened.

The molecular weight can be measured, for example, using gel permeation chromatography (GPC, Tosoh Corporation HLC-8220GPC) by mixing each carbon material in N,N-dimethylformamide (containing 0.1% LiBr) so that the carbon material is 0.02% by mass, ultrasonicating for 1 hour, and then passing the mixture through a PTFE filter paper (0.45 μm) as a pretreatment. The filtrate can then be calculated in polystyrene equivalent terms using N,N-dimethylformamide (containing 0.1% LiBr) as the developing solvent. The maximum molecular weight in the carbon material can be calculated from the rising point of the peak.

The content of the carbon-based compound in the carbon material in the organic-inorganic composite is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, even more preferably 90% by mass to 100% by mass, particularly preferably 95% by mass to 100% by mass, and most preferably substantially 100% by mass. If the content of the carbon-based compound in the carbon material in the organic-inorganic composite is within the above range, the solubility of the carbon material in the organic-inorganic composite in the solvent is improved in combination with the above features (i) and (ii) (for example, more components of the carbon material dissolve in the solvent, or more types of solvents in which the carbon material can be dissolved).

The carbon material in the organic-inorganic composite preferably exhibits a peak in the range of 20° to 30° in an XRD spectrum chart obtained by XRD analysis. In one preferred embodiment, the carbon material has a structure in which graphene structures are stacked (graphene stacked structure). By having a stacked structure, the carbon material in the organic-inorganic composite can be stronger and more stable.

The XRD measurement can be performed, for example, using a fully automatic horizontal X-ray diffractometer (SMART LAB, manufactured by Rigaku Corporation) under the following conditions.
CuKα1 line: 0.15406nm
Scanning range: 10°-90°
X-ray output setting: 45 kV-200 mA
Step size: 0.020°
Scan speed: 0.5°min ⁻¹ to 4°min ⁻¹

The XRD measurements can be performed in an inert atmosphere by loading the sample onto an airtight sample stage in a glove box.

The carbon material in the organic-inorganic composite may preferably exist in a bulk state. In general, the properties of a substance in a bulk state are the inherent properties of that substance. That is, for a substance in a bulk state, the basic properties of that substance, such as the boiling point, melting point, viscosity, and density, can be determined. The physical properties of a substance refer to the properties of the bulk portion. Examples of bulk states include particles, pellets, and films. Examples of the state in which particles exist include powder. As for the film, it is preferable that it is a free-standing film.

<1-1-2-1. Compound (A)>
In the first embodiment, the compound (A) undergoes a condensation reaction between the same molecules and/or between different molecules by heating, so that the composition containing the compound (A) and inorganic particles is heated in the heating step (I), Typically, the compound (A) can be a carbon material.

Compound (A) is preferably solid in a 23°C environment and has a melting point. By having a melting point, it melts during the firing process and the reaction between molecules proceeds smoothly. If it does not have a melting point, it will not melt during the firing process, so the position of the molecules will be fixed, and the reaction between molecules will not be promoted easily, making it difficult to turn into a carbon material. By using such a compound (A), it is possible to promote condensation reactions, suppress decomposition reactions, and improve the solubility of the carbon material in the solvent (for example, more components of the carbon material will dissolve in the solvent, or the number of types of solvents in which the carbon material can be dissolved will increase).

It is preferable that the skeleton of compound (A) that does not contribute to condensation is an aromatic structure. By having an aromatic skeleton, the carbon component of the resulting carbon material can be more stable. Examples of such aromatic structures are aromatic structures consisting of carbon atoms, such as benzene and naphthalene; heteroaromatic structures consisting of carbon atoms and heteroatoms (such as nitrogen and oxygen), such as pyridine, pyrimidine, furan, and thiophene; and among these, aromatic structures and heteroaromatic structures having a six-membered ring structure, such as benzene and pyridine, are more preferable.

The molecular weight of compound (A) may be any appropriate molecular weight within a range that does not impair the effects of the present invention. In order to better express the effects of the present invention, such a molecular weight is preferably 500 or less, more preferably 75 to 450, even more preferably 80 to 400, and most preferably 100 to 350.

The condensation reaction temperature of compound (A) may be any appropriate temperature within a range that does not impair the effects of the present invention. In order to more effectively exert the effects of the present invention, the condensation reaction temperature is preferably 450°C or less, more preferably 400°C or less, even more preferably 200°C to 370°C, and particularly preferably 250°C to 350°C.

When TG-DTA analysis of compound (A) is performed under nitrogen gas atmosphere with a temperature rise condition of 10°C/min from 40°C, the mass ratio (M500/M50) of the mass M500 at a temperature of 500°C to the initial mass M50 at a temperature of 50°C is preferably 0.2 or more, more preferably 0.2 to 0.9, and most preferably 0.3 to 0.8, in order to further demonstrate the effects of the present invention. By using compound (A) whose mass ratio (M500/M50) falls within the above range, the carbon material can be sufficiently left in the organic-inorganic composite obtained after heating.

[1-1-2-1-1. Preferred embodiment 1 of compound (A)]
A preferred embodiment 1 of the compound (A) is an aromatic compound that is decomposed by heating to generate radicals on the aromatic ring. The aromatic compound having radicals on the aromatic ring can undergo a condensation reaction between the same molecules and/or different molecules to become a carbon material.

The aromatic compound that decomposes when heated to generate radicals on the aromatic ring is preferably an aromatic compound that generates a gas (a gas that is in a gaseous state at room temperature and normal pressure) when heated.

As the aromatic compound that generates a gas when heated, any appropriate aromatic compound can be used as long as it is an aromatic compound that generates a gas when heated. The gas that is in a gaseous state at normal temperature and pressure is preferably at least one selected from CO, _CO2 , _N2 , _O2 , _H2 , and _NO2 .

Examples of aromatic compounds that generate CO and/or _CO2 upon heating include aromatic compounds having a "-C(=O)-" and/or "-O-C(=O)-" structure (e.g., aromatic ketone derivatives, aromatic ester derivatives, acid anhydrides, etc.).

Examples of aromatic compounds that generate CO and/or _CO2 when heated include the following compounds:

Examples of aromatic compounds that generate _N2 upon heating include aromatic compounds having an "-NH-NH-" structure, an "-N=N-" structure, or an " _-N3 " structure (e.g., aromatic azo compounds, aromatic azide compounds, triazole-substituted aromatic compounds, tetrazole-substituted aromatic compounds, triazine or derivatives thereof, tetrazine or derivatives thereof, aromatic hydrazine derivatives, etc.).

Examples of aromatic compounds that generate _N2 upon heating include the following compounds: In the following compounds, R represents a hydrogen atom, or an alkyl group, an aryl group, or a heteroaryl group which may have a substituent.

Examples of aromatic compounds that generate _O2 when heated include aromatic compounds having an "-O-O-" structure (e.g., aromatic carbon oxides, aromatic peroxides, etc.).

Examples of aromatic compounds that generate _O2 upon heating include the following compounds. In the following compounds, R represents a hydrogen atom, or an alkyl group, an aryl group, or a heteroaryl group that may have a substituent.

Examples of aromatic compounds that generate H ₂ when heated include condensed polycyclic aromatic compounds having a "-CH ₂ -" structure (such as phenalene compounds).

Examples of aromatic compounds that generate _H2 upon heating include the following compounds:

Examples of aromatic compounds that generate _NO2 when heated include aromatic compounds having a " _-NO2 " structure (such as aromatic nitro compounds).

Examples of aromatic compounds that generate _NO2 when heated include the following compounds:

Aromatic compounds that decompose by heating to generate radicals on aromatic rings are compounds that have decomposability by heating, and at least a part of the skeleton is dissociated and decomposed to generate gas molecules (preferably at least one selected from CO, CO ₂ , N ₂ , O ₂ , H ₂ , and NO ₂ ), and radicals are generated on the remaining aromatic ring. By using such aromatic compounds, a reaction occurs only by the decomposition of the compound itself without the need for a reaction catalyst, so that by-products of chemical reactions and reaction catalysts can be prevented from being present in the carbon material and becoming fatal impurities, and a higher quality carbon material can be obtained. In addition, by using such aromatic compounds, a carbon material can be obtained in a relatively mild temperature environment without using flammable gases. In addition, such aromatic compounds can have high reactivity without the need for catalytic action.

[1-1-2-1-2. Another preferred embodiment 2 of compound (A)]
Another preferred embodiment 2 of the compound (A) is a compound in which one neutral molecule is formed and eliminated from two or more groups by a condensation reaction. In this embodiment 2, one compound may have two or more groups, or two or more compounds may combine their respective groups to form two or more groups. Such a compound (A) may undergo a condensation reaction between the same molecules and/or between different molecules to become a carbon material.

As the condensation reaction, any appropriate condensation reaction can be adopted as long as it is a condensation reaction in which one neutral molecule is formed from two or more groups and then eliminated, as long as it does not impair the effects of the present invention. By adopting such a condensation reaction, it may be possible to carry out the reaction at a relatively low temperature. Examples of such condensation reactions include
(a) a condensation reaction in which H ₂ O is formed and eliminated from —H groups and —OH groups;
(b) a condensation reaction between an -H group and an -OR group, where R is any suitable substituted or unsubstituted alkyl group, to form and eliminate ROH;
(c) a condensation reaction of a -H group with a -X group (wherein X is a halogen or CN) to form and eliminate HX;
(d) condensation reaction of -H group with _-NH2 group with formation and elimination of _NH3 ;
(e) a condensation reaction between an -H group and an -NHR group (wherein R is any suitable substituted or unsubstituted alkyl group) by the formation and elimination of _RNH2 ;
(f) a condensation reaction between an -H group and a -NR ¹ R ² group (where R ¹ and R ² are any suitable substituted or unsubstituted alkyl groups) to form and eliminate R ¹ R ² NH;
(g) a condensation reaction in which H ₂ S is formed and eliminated from a -H group and a -SH group;
(h) a condensation reaction between an -H group and a -SR group, where R is any suitable substituted or unsubstituted alkyl group, to form and eliminate RSH;
(i) a condensation reaction between an -H group and an -OOCR group (wherein R is any suitable substituted or unsubstituted alkyl group) to form and eliminate RCOOH;
(j) a condensation reaction between a -H group and a -OSO(OH) group with the formation and elimination _{of H2SO3} ;
(k) a condensation reaction between an -H group and an -OSO ₂ R group, where R is any suitable substituted or unsubstituted alkyl group, to form and eliminate RSO ₂ (OH);
(l) a condensation reaction between an -H group and _{an -OSO2} (OR) group, where R is any suitable substituted or unsubstituted alkyl group, to form and eliminate _ROSO3H ;
(m) a condensation reaction between a -H group and _a -OSO2(OH) group, with the formation and elimination _{of H2SO4} ;
In particular, if the desorbed neutral components are gaseous components at the desorption temperature (calcination temperature), they are not incorporated into the carbon material and remain in the gas phase, and therefore are unlikely to become impurities.

As a representative example of the condensation reaction, the condensation reaction (a) above) in which H ₂ O is formed and eliminated from a —H group and a —OH group will be described.

One embodiment of compound (A) in embodiment 2 (sometimes referred to as embodiment (X)) is compound (a1) having a skeleton consisting of one six-membered carbon ring structure or compound (a2) having a skeleton in which two or more six-membered carbon ring structures are bonded and/or condensed, and half of the substituents that do not contribute to the formation of the skeleton are -OH groups and the other half are -H groups.

In embodiment (X),
(i) When compound (A) is compound (a1) having a skeleton consisting of one 6-membered carbon ring structure,
(ii) When compound (A) is compound (a2) having a skeleton in which two or more 6-membered carbon ring structures are bonded and/or condensed,
Either of the following two cases can be adopted.

In embodiment (X), "substituents that do not contribute to the formation of the skeleton" refer to the "skeleton consisting of one carbon six-membered ring structure" in the above case (i) or the "skeleton consisting of two or more carbon six-membered ring structures bonded and/or condensed" in the above case (ii). For example, in the above case (i), when compound (a1) having a skeleton consisting of one carbon six-membered ring structure is represented by the chemical formula (a1-1) shown later, the substituents that do not contribute to the formation of the skeleton consisting of one carbon six-membered ring structure are six -OH groups and six -H groups, and when compound (a1) having a skeleton consisting of one carbon six-membered ring structure is represented by the chemical formula (a1-2) shown later, the substituents that do not contribute to the formation of the skeleton consisting of one carbon six-membered ring structure are three -OH groups and three -H groups. Also, for example, in the case of (ii) above, when compound (a2) having a skeleton in which two or more 6-membered carbon ring structures are bonded and/or fused is represented by the chemical formula (a2-1) shown below, the substituents that do not contribute to the formation of the structure of the skeleton in which two or more 6-membered carbon ring structures are bonded and/or fused are six -OH groups and six -H groups.

In embodiment (X), half of the substituents not contributing to the formation of the structure of compound (a1) having a skeleton consisting of one 6-membered carbon ring structure are -OH groups and the other half are -H groups, and half of the substituents not contributing to the formation of the structure of compound (a2) having a skeleton in which two or more 6-membered carbon ring structures are bonded and/or condensed are -OH groups and the other half are -H groups. By having such a substituent configuration, compound (A) can effectively undergo a dehydration reaction between identical molecules and/or different molecules when heated.

Compounds (A) that can be used in embodiment (X) include compounds (a1) having a skeleton consisting of one 6-membered carbon ring structure, or compounds (a2) having a skeleton in which two or more 6-membered carbon ring structures are bonded and/or condensed, and any appropriate compound can be used as long as it does not impair the effects of the present invention, as long as half of the substituents that do not contribute to the formation of the skeleton are -OH groups and the other half are -H groups. Examples of such compounds (A) include the following compounds.

Among the compounds (A) that can be used in embodiment (X), phloroglucinol (compound (a1-2)) and hexahydroxytriphenylene (HHTP) (compound (a2-1)) are preferred, since they are presumed to easily undergo a condensation reaction in which H ₂ O is formed from a -H group and a -OH group and then eliminated, and the reaction is presumed to proceed easily at low temperatures.

Another embodiment of compound (A) in embodiment 2 (sometimes referred to as embodiment (Y)) is two or more compounds selected from compound (a1) having a skeleton consisting of one 6-membered carbon ring structure and/or compound (a2) having a skeleton in which two or more 6-membered carbon ring structures are bonded and/or condensed, in which half of the total number of substituents not contributing to the formation of the skeleton structure of compound (a1) and the total number of substituents not contributing to the formation of the skeleton structure of compound (a2) are -OH groups, and the other half are -H groups.

In embodiment (Y),
(i) When the compound (A) is composed of two or more compounds selected from the compound (a1) having a skeleton consisting of one 6-membered carbon ring structure,
(ii) When the compound (A) is composed of two or more compounds selected from the group consisting of compounds (a2) having a skeleton in which two or more 6-membered carbon ring structures are bonded and/or condensed,
(iii) when compound (A) is composed of one or more compounds (a1) having a skeleton consisting of one 6-membered carbon ring structure and one or more compounds (a2) having a skeleton consisting of two or more 6-membered carbon ring structures bonded and/or condensed,
One of the following three cases can be adopted.

In embodiment (Y), "the total number of substituents that do not contribute to the formation of the skeleton of compound (a1) and the total number of substituents that do not contribute to the formation of the skeleton of compound (a2)" has the following meaning. That is, in the case of (i) above, it means the total number of substituents that do not contribute to the formation of the skeleton of "a skeleton consisting of one carbon 6-membered ring structure" in each of two or more compounds (a1). In the case of (ii) above, it means the total number of substituents that do not contribute to the formation of the skeleton of "a skeleton consisting of two or more carbon 6-membered ring structures" in each of two or more compounds (a2). In the case of (iii) above, it means the total number of substituents that do not contribute to the formation of the skeleton of "a skeleton consisting of one carbon 6-membered ring structure" in each of one or more compounds (a1) and the total number of substituents that do not contribute to the formation of the skeleton of "a skeleton consisting of two or more carbon 6-membered ring structures" in each of one or more compounds (a2).

In embodiment (Y), for example, in the case of (i) above, when two or more types of compounds (a1) are represented by the following chemical formulas (a1-5) and (a1-6), the substituents that do not contribute to the formation of the structure of the skeleton consisting of one six-membered carbon ring structure of the compound represented by chemical formula (a1-5) are two -OH groups and four -H groups, and the substituents that do not contribute to the formation of the structure of the skeleton consisting of one six-membered carbon ring structure of the compound represented by chemical formula (a1-6) are four -OH groups and two -H groups, for a total of six -OH groups and six -H groups. For example, in the case of (iii) above, when one or more compounds (a1) are represented by the following chemical formulas (a1-5) and (a1-7), and one or more compounds (a2) are represented by the following chemical formula (a2-3), the substituents that do not contribute to the formation of a skeleton structure consisting of one 6-membered carbon ring structure of the compound represented by chemical formula (a1-5) are two -OH groups and four -H groups, the substituents that do not contribute to the formation of a skeleton structure consisting of one 6-membered carbon ring structure of the compound represented by chemical formula (a1-7) are six -OH groups, and the substituents that do not contribute to the formation of a skeleton structure consisting of two or more bonded and/or condensed 6-membered carbon ring structures of the compound represented by chemical formula (a2-3) are two -OH groups and six -H groups.

By using such a compound (A), the reaction occurs by its own dehydration reaction without the need for a reaction catalyst, so it is possible to prevent by-products of the chemical reaction or reaction catalysts from being present in the carbon material and becoming fatal impurities, and a higher quality carbon material can be obtained. In addition, by using such a compound (A), it is possible to obtain a carbon material in a relatively mild temperature environment without using flammable gases. In addition, such a compound (A) can have high reactivity without the need for catalytic action.

A preferred embodiment of compound (A) in embodiment 2 is a compound having three or more phenolic hydroxyl groups in the molecule.

As the compound having three or more phenolic hydroxyl groups in the molecule, any suitable compound having three or more phenolic hydroxyl groups in the molecule may be used as long as it does not impair the effects of the present invention.

In a compound having three or more phenolic hydroxyl groups in the molecule, the aromatic ring to which the phenolic hydroxyl groups are bonded is preferably a hydrocarbon aromatic ring. The effects of the present invention can be achieved even if the aromatic ring to which the phenolic hydroxyl groups are bonded is a heteroaromatic ring, but the carbon material obtained can be more stable if the aromatic ring has a more stable ring structure. Note that a heteroaromatic ring means an aromatic ring whose ring structure is formed by carbon and an element other than carbon, unlike a hydrocarbon aromatic ring whose ring structure is formed by carbon.

A compound having three or more phenolic hydroxyl groups in a molecule may have a substituent other than the phenolic hydroxyl group. Any suitable substituent may be used as such a substituent as long as it does not impair the effects of the present invention. In terms of further enhancing the effects of the present invention, it is preferable that such a substituent is only a hydroxyl group. Although the effects of the present invention can be achieved even if a substituent other than a hydroxyl group is present, it is easier to prevent side reactions and to make a carbon material if no substituent other than a hydroxyl group is present. Note that the "hydroxyl group" as a substituent other than a phenolic hydroxyl group referred to here means a hydroxyl group that is not phenolic. Note that, as a matter of course, a substituent is a group that is substituted in place of a hydrogen group (-H).

As the elements constituting the compound having three or more phenolic hydroxyl groups in the molecule, any appropriate elements may be used as long as they do not impair the effects of the present invention. In terms of enhancing the effects of the present invention, it is preferable that such elements are only carbon, oxygen, and hydrogen. Although the effects of the present invention can be achieved even if elements other than carbon, oxygen, and hydrogen are present, it is easier to prevent side reactions and to convert the material into a carbon material if no elements other than carbon, oxygen, and hydrogen are present.

For compounds having three or more phenolic hydroxyl groups in the molecule, the condensation reaction temperature of the compound is preferably in the range of 200°C to 450°C, and more preferably in the range of 200°C to 400°C, in order to maximize the effects of the present invention. This allows the compound to be effectively converted into a carbon material.

The compound having three or more phenolic hydroxyl groups in the molecule may be of only one type, or of two or more types. Even in the case of two or more types, it is preferable that the condensation reaction temperature between the molecules is within the above-mentioned range.

Examples of compounds having three or more phenolic hydroxyl groups in the molecule include the compounds shown in general formulas (1) to (11).

In each of the general formulas (1) to (11), X represents a hydrogen atom or a hydroxyl group, and three or more of the X's are hydroxyl groups (phenolic hydroxyl groups).

Here, the phenolic hydroxyl group means a hydroxyl group bonded to an aromatic ring. That is, in general formula (1), three or more of the six Xs bonded to the aromatic ring are phenolic hydroxyl groups, in general formula (2), three or more of the six Xs bonded to the aromatic ring are phenolic hydroxyl groups, in general formula (3), three or more of the ten Xs bonded to the aromatic ring are phenolic hydroxyl groups, in general formula (4), three or more of the eleven Xs bonded to the aromatic ring are phenolic hydroxyl groups, in general formula (5), three or more of the nine Xs bonded to the aromatic ring are phenolic hydroxyl groups, and in general formula (6), nine Xs bonded to the aromatic ring are phenolic hydroxyl groups. In general formula (7), three or more of the ten Xs bonded to the aromatic ring are phenolic hydroxyl groups; in general formula (8), three or more of the eleven Xs bonded to the aromatic ring are phenolic hydroxyl groups; in general formula (9), three or more of the nine Xs bonded to the aromatic ring are phenolic hydroxyl groups; in general formula (10), three or more of the nine Xs bonded to the aromatic ring are phenolic hydroxyl groups; and in general formula (11), three or more of the twelve Xs bonded to the aromatic ring are phenolic hydroxyl groups.

Among compounds having three or more phenolic hydroxyl groups in the molecule, phloroglucinol and hexahydroxytriphenylene are preferred, and phloroglucinol is more preferred, since it is believed that a condensation reaction is likely to occur due to the formation and elimination of H ₂ O from the -H group and the -OH group, and the reaction is likely to proceed easily.

[1-1-2-1-3. Further preferred embodiment 3 of compound (A)]
Yet another embodiment 3 of the compound (A) is an embodiment in which both the embodiment 1 and the embodiment 2 are simultaneously adopted. That is, the embodiment 3 is an aromatic compound that decomposes upon heating to generate radicals on the aromatic ring, and is a compound in which one neutral molecule is formed and eliminated from two or more types of groups by a condensation reaction. Such a compound (A) can undergo a condensation reaction between the same molecules and/or between different molecules to become a carbon material.

An example of a specific structure of embodiment 3 is compound (a3-1). When compound (a3-1) is heated, carbon dioxide molecules are eliminated, generating radicals (reactive sites) on the aromatic ring, and the hydroxyl group and hydrogen group undergo intermolecular dehydration, causing a condensation reaction.

By using such a compound (A), the reaction occurs by its own dehydration reaction without the need for a reaction catalyst, so it is possible to prevent by-products of the chemical reaction or reaction catalysts from being present in the carbon material and becoming fatal impurities, and a higher quality carbon material can be obtained. In addition, by using such a compound (A), it is possible to obtain a carbon material in a relatively mild temperature environment without using flammable gases. In addition, such a compound (A) can have high reactivity without the need for catalytic action.

<1-1-3. Details of the lubricating filler according to embodiment 1>
As shown in Fig. 1, an organic-inorganic composite 100 in which a plurality of inorganic particles 20 are dispersed in a carbon material 10 as a matrix can be said to be a lubricating filler in which the surface of an inorganic particle is coated with a carbon material, and therefore can correspond to the lubricating filler according to embodiment 1. Also, as shown in Fig. 2, a core-shell particle (core part: inorganic particle, shell part: carbon material bonding region) 200 in which the surface of an inorganic particle 20 is coated with a carbon material bonding region (region that is not dissolved by a solvent) 30, and a highly carbonized core-shell particle in which the shell part is highly carbonized can be said to be a lubricating filler in which the surface of an inorganic particle is coated with a carbon material, and therefore can correspond to the lubricating filler according to embodiment 1.

In the organic-inorganic composite 100 shown in FIG. 1, a carbon material region (carbon material bonded region) 30 is present at the interface between the carbon material 10 and the inorganic particle 20, typically resulting from the carbon material forming a bond with a functional group present on the surface of the inorganic particle 20. In this case, for example, when the carbon material is soluble in a solvent, a carbon material removal step is performed in which the organic-inorganic composite 100 is treated with a solvent that dissolves the carbon material, and a heating step (II) is further performed as necessary, thereby obtaining a core-shell particle (core part: inorganic particle, shell part: carbon material bonded region) 200 in which the surface of the inorganic particle 20 is coated with a carbon material bonded region (region that is not dissolved by the solvent) 30, as shown in FIG. 2. The core-shell particle 200 obtained when the heating step (II) is performed is a highly carbonized core-shell particle.

The carbon material 10 as the matrix in FIG. 1 and the carbon material bonding region (region that is not dissolved by the solvent) 30 in FIG. 2 correspond to the carbon material in the lubricating filler according to embodiment 1. In terms of being able to more effectively express the effects of the present invention, the lubricating filler according to the embodiment of the present invention is preferably a core-shell particle 200 (including the case of a highly carbonized core-shell particle) shown in FIG. 2, and in this case, the carbon material bonding region (region that is not dissolved by the solvent) 30 present on the surface of the inorganic particle 20 corresponds to the carbon material in the lubricating filler according to embodiment 1.

When the carbon material is soluble in a solvent, a carbon material removal step is performed in which the organic-inorganic composite is treated with a solvent that dissolves the carbon material, and a heating step (II) is further performed as necessary, whereby a lubricating filler according to an embodiment of the present invention can be obtained as shown in FIG. 2, in the form of a core-shell particle (core portion: inorganic particle, shell portion: carbon material bonding region) 200 in which the surface of an inorganic particle 20 is coated with a carbon material bonding region (region that is not dissolved by the solvent) 30. The core-shell particle obtained by performing the heating step (II) has a shell portion that is highly carbonized, becoming a highly carbonized core-shell particle (core portion: inorganic particle, shell portion: highly carbonized material).

The carbon material coated on the surface of the inorganic particles can be typically produced by subjecting the organic-inorganic composite to a carbon material removal step in which a portion of the carbon material produced by heating the compound (A) is removed after the heating step (I) during the production of the organic-inorganic composite.

In the carbon material removal process, the organic-inorganic composite is treated with a solvent that dissolves the carbon material contained in the organic-inorganic composite. As a result, as shown in FIG. 2, a core-shell particle (core part: inorganic particle, shell part: carbon material bonding region) 200 can be obtained in which the surface of the inorganic particle 20 is coated with a carbon material bonding region (region that is not dissolved by the solvent) 30. This core-shell particle can correspond to the lubricating filler according to embodiment 1.

Examples of solvents that dissolve the carbon material contained in the organic-inorganic composite include N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, methanol, ethanol, 2-propanol, butanol, chloroform, and dichloromethane. Preferred are N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, and chloroform, and more preferred are N,N-dimethylformamide and N-methylpyrrolidone.

By carrying out the heating step (II) after carrying out the carbon material removal step, as described above, the shell portion is highly carbonized, and highly carbonized core-shell particles (core portion: inorganic particles, shell portion: highly carbonized material) can be obtained. These highly carbonized core-shell particles can correspond to the lubricating filler according to embodiment 1. When the lubricating filler according to embodiment 1 is a highly carbonized core-shell particle, the strength and heat resistance can be improved.

The heating temperature in the heating step (II) may be any suitable temperature within a range that the inorganic particles of the core portion can withstand, as long as the effects of the present invention are not impaired. Such a heating temperature is preferably 500°C to 3000°C, more preferably 600°C to 2500°C, and most preferably 700°C to 2000°C. By adjusting the heating temperature in the heating step (II) to within the above range, the shell portion can be effectively highly carbonized.

The specific heating time in the heating step (II) is preferably 0.1 to 120 hours, more preferably 0.5 to 100 hours, even more preferably 1 to 50 hours, and most preferably 2 to 24 hours. By adjusting the heating time to within the above range, the shell portion can be effectively highly carbonized.

<<1-2. Another preferred embodiment 2 of the lubricating filler>>
A second preferred embodiment of the lubricating filler is a lubricating filler obtained by a method including a mixing step (I) of mixing a soluble carbon material that is soluble in a solvent (S) and inorganic particles in the solvent (S).

In embodiment 2, the soluble carbon material and inorganic particles are mixed in a solvent (S). In embodiment 2, the soluble carbon material and inorganic particles are simply mixed in the solvent (S) without firing the soluble carbon material or its precursor, an organic compound, and inorganic particles in a coexisting state, and the lubricating filler can be obtained. In other words, in embodiment 2, there is no need to fire the soluble carbon material and inorganic particles in a coexisting state, and the thermal energy required for firing can be reduced, so the lubricating filler can be easily produced under mild conditions.

Representative preferred forms of the lubricating filler obtained in embodiment 2 are the following four forms of lubricating filler. However, the lubricating filler obtained in embodiment 2 may be other than the following four forms as long as the effects of the present invention are not impaired.
(i) A lubricating filler dispersion in which a lubricating filler having an inorganic particle portion and a carbon material portion (either an embodiment in which only the carbon material portion exists on the surface of the inorganic particle portion by strongly interacting with the outermost surface of the inorganic particle portion, or an embodiment in which both the carbon material portion and a carbon material portion that can be removed by the soluble carbon material removal step (IIb)) is dispersed in a solvent (S).
(ii) A lubricating filler having an inorganic particle portion and a carbon material portion (either the carbon material portion is present on the surface of the inorganic particle portion by strongly interacting with the outermost surface of the inorganic particle portion, or the carbon material portion and a carbon material portion that can be removed by the soluble carbon material removal step (IIb)) obtained by subjecting the lubricating filler dispersion of (i) above to a solvent removal step (IIa) (typically, an "organic-inorganic composite" described later).
(iii) A lubricating filler (typically, the "organic-inorganic composite" described later) having an inorganic particle portion and a carbon material portion (substantially only the carbon material portion that strongly interacts with the outermost surface of the inorganic particle portion and is present on the surface of the inorganic particle portion) obtained by subjecting the lubricating filler (ii) above (typically, the "organic-inorganic composite" described later) to a soluble carbon material removal step (IIb). (Typically, the "core-shell particle" described later).
(iv) A lubricating filler (typically, the "core-shell particles" described later) obtained by subjecting the lubricating filler (iii) above (typically, the "core-shell particles" described later) to a heating step (III) in which the lubricating filler is further heated (typically, the "highly carbonized core-shell particles" described later).

The lubricating filler according to embodiment 2 may ultimately be in any suitable state. For example, the lubricating filler may be in a dispersion state in which it is dispersed in a solvent, or may be in a solid state (e.g., particulate, fibrous, thin film, plate, etc.) from which the solvent has been removed.

The carbon material portion contained in the lubricating filler according to embodiment 2 is typically
(i) a raw soluble carbon material;
(ii) a carbon material derived from a raw material soluble carbon material, which carbon material is present on the surface of an inorganic particle by strongly interacting with the outermost surface of the inorganic particle;
(iii) a highly carbonized carbon material obtained by subjecting the carbon material of (ii) above to a heating step (III) to high carbonization;
etc.

By the mixing step (I) in which the soluble carbon material and the inorganic particles are mixed in the solvent (S), a lubricating filler in the form of a lubricating lubricant containing inorganic particles can typically be obtained (in this case, a particulate lubricating filler can be obtained by crushing or the like). In addition, by adjusting the blending ratio of the soluble carbon material and the inorganic particles, a particulate lubricating filler can also be obtained by the mixing step (I) in which the soluble carbon material and the inorganic particles are mixed in the solvent (S).

In the mixing step (I), a soluble carbon material that is soluble in the solvent (S) and inorganic particles are mixed in the solvent (S).

As a mixing method, any appropriate mixing method may be adopted as long as it does not impair the effects of the present invention. For example, such a mixing method may include a method in which the soluble carbon material, the inorganic material, and the solvent (S) are mixed by any appropriate method (e.g., ultrasonic treatment, etc.). In this case, the soluble carbon material and the inorganic particles may be mixed after any appropriate treatment (e.g., crushing, crushing, pulverization, etc.).

Any appropriate mixing temperature may be adopted as long as it does not impair the effects of the present invention. Such a mixing temperature is preferably 0°C to 100°C, more preferably 10°C to 90°C, and even more preferably 20°C to 80°C, in order to better express the effects of the present invention. By keeping the temperature within the above range, the soluble carbon material can be dissolved sufficiently quickly and mixed with the inorganic particles.

When mixing, any suitable other components other than the soluble carbon material, inorganic particles, and solvent (S) may be included as long as they do not impair the effects of the present invention.

The blending ratio of the soluble carbon material and the inorganic particles is preferably 0.01% by mass to 1,000,000% by mass, more preferably 0.1% by mass to 100,000% by mass, and particularly preferably 1% by mass to 1,000% by mass, relative to 100% by mass of the inorganic particles. If the blending ratio of the soluble carbon material and the inorganic particles is within the above range, the lubricating filler can be produced more easily under milder conditions. The blending ratio of these soluble carbon materials and the inorganic particles can be adjusted arbitrarily depending on the physical properties of the desired lubricating filler. For example, by adjusting the blending ratio of the soluble carbon material and the inorganic particles, the physical properties and form of the obtained lubricating filler (for example, solubility in a solvent, the shape of the carbon material portion or the inorganic particle portion (particulate or non-particulate), the size of the carbon material portion or the inorganic particle portion, etc.) can be controlled. In addition, a higher proportion of soluble carbon material will quickly combine with the inorganic particles, while a lower proportion of soluble carbon material will be easier to remove in the subsequent soluble carbon material removal step (IIb).

≪1-2-1. Inorganic particles≫
As the inorganic particles, any appropriate inorganic particles can be adopted as long as the effects of the present invention are not impaired.

There may be only one type of inorganic particles, or two or more types.

The inorganic particles may be, for example, at least one selected from the group consisting of inorganic oxide particles, inorganic nitride particles, inorganic sulfide particles, inorganic carbide particles, and insoluble salt particles.

For inorganic oxide particles, the explanation in the above section <1-1-1-1. Inorganic oxide particles> may be used.

For inorganic nitride particles, the explanation in the above section <1-1-1-2. Inorganic nitride particles> may be used.

For inorganic sulfide particles, the explanation in the above section [1-1-1-3. Inorganic sulfide particles] may be used.

For inorganic carbide particles, the explanation in the above section <1-1-1-4. Inorganic carbide particles> may be used.

For insoluble salt particles, the explanation in the above section <1-1-1-5. Insoluble salt particles> may be used.

In the second embodiment, taking into consideration the surface characteristics, preferred examples of inorganic particles include inorganic particles having a basic surface and inorganic particles having a surface capable of π-π interactions.

Inorganic particles with basic surfaces can bond more strongly to soluble carbon materials through acid-base interactions when the soluble carbon materials have acid groups (e.g., phenolic hydroxyl groups).

Inorganic particles with a surface capable of π-π interactions can bond more firmly with a soluble carbon material through π-π interactions if the soluble carbon material has π electrons.

As the inorganic particles having a basic surface, any suitable inorganic particles having a basic surface may be used as long as the effect of the present invention is not impaired. Examples of such inorganic particles having a basic surface include inorganic particles made of a substance having a basic surface, such as inorganic substances such as alumina, magnesium oxide, and aluminum nitride, and organic substances such as benzoguanamine-formaldehyde condensates, benzoguanamine-melamine-formaldehyde condensates, and melamine-formaldehyde condensates. In addition, as the inorganic particles having a basic surface, inorganic particles having at least the above-mentioned substance having a basic surface on the surface thereof may be preferably used.

As the inorganic particles having a surface capable of π-π interaction, any suitable inorganic particles having a surface capable of π-π interaction may be used as long as the effects of the present invention are not impaired. Examples of such inorganic particles having a surface capable of π-π interaction include inorganic particles made of a substance having a surface capable of π-π interaction, such as inorganic substances such as boron nitride and graphite, and organic substances such as benzoguanamine-formaldehyde condensates, benzoguanamine-melamine-formaldehyde condensates, and melamine-formaldehyde condensates. Note that, as the inorganic particles having a surface capable of π-π interaction, inorganic particles having at least the above-mentioned substance having a surface capable of π-π interaction on their surface may be preferably used.

≪1-2-2. Soluble carbon material≫
The soluble carbon material is a carbon material that is soluble in a solvent (S). Here, when a carbon material is soluble in a solvent (S), it means that the carbon material is more soluble in the solvent than conventional carbon materials. In this case, excellent and easy handling can be realized.

The carbon material may be soluble in the solvent (S) preferably in the following manner.
(Embodiment 1) An embodiment in which the entire carbon material is dissolved in the solvent (S), i.e., an embodiment in which the carbon material is composed only of a component (component A) that is soluble in the solvent (S).
(Embodiment 2) An embodiment in which a part of the carbon material dissolves in the solvent (S). That is, an embodiment in which the carbon material comprises a component (component A) that dissolves in the solvent (S) and a component (component B) that does not dissolve in the solvent (S).

In the present invention, "soluble in solvent (S)" means an embodiment in which there is a component that dissolves in any suitable solvent (S). Any suitable solvent may be used as the solvent (S) as long as it does not impair the effects of the present invention. As such a solvent (S), preferably, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, methanol, ethanol, 2-propanol, butanol, chloroform, dichloromethane, etc. are mentioned. That is, an embodiment in which there is a component that dissolves in at least one solvent selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, methanol, ethanol, 2-propanol, butanol, chloroform, dichloromethane, and water (including acidic and basic water) is preferable. More preferably, the composition contains a component that dissolves in at least one solvent selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, and chloroform; even more preferably, the composition contains a component that dissolves in at least one solvent selected from the group consisting of N,N-dimethylformamide and N-methylpyrrolidone; and particularly preferably, the composition contains a component that dissolves in N-methylpyrrolidone.

The solvent (S) may consist of only one type of solvent, or may be a mixture of two or more types of solvents.

One embodiment in which the carbon material is soluble in the solvent (S) is, for example, an embodiment in which the carbon material includes a carbon-based compound that is soluble in the solvent (S).

As a method for determining whether or not a material is soluble in a solvent (S), for example, a carbon material is mixed with the solvent (S) so that the concentration is 0.001% by mass, and then ultrasonic treatment is performed for 1 hour. When the resulting liquid is passed through a PTFE filter paper (pore size 0.45 μm), it can be determined whether or not the liquid that passes through the filter paper contains a carbon-based compound. If the liquid that passes through the filter paper contains a carbon-based compound, it is determined that the carbon material contains a carbon-based compound that is soluble in the solvent. As the PTFE filter paper, for example, a GL Chromatodisc (Model 13P) manufactured by GL Sciences Inc. can be used.

Soluble carbon materials are typically obtained by heating a compound (A) that undergoes a condensation reaction between identical molecules and/or different molecules upon heating.

When the condensation reaction temperature of compound (A) is T°C, the heating temperature of compound (A) to obtain a soluble carbon material is preferably (T-150)°C or higher, more preferably (T-150 to T+50)°C, even more preferably (T-130 to T+45)°C, even more preferably (T-100 to T+40)°C, particularly preferably (T-80 to T+35)°C, and most preferably (T-50 to T+30)°C.

As described above, the reaction of the soluble carbon material can proceed from a relatively low temperature compared to the condensation reaction temperature of compound (A), and carbonization can proceed. By adjusting the heating temperature to within the above range, it is possible to more easily produce a soluble carbon material that is more soluble in a solvent or a soluble carbon material whose structure is more precisely controlled under milder conditions.

The condensation reaction temperature of the compound (A) can be determined by TG-DTA analysis. Specifically, it is as follows.
(1) When one type of compound is used as compound (A), the TG-DTA analysis of compound (A) is performed in a nitrogen gas atmosphere by increasing the temperature from 40° C. at a temperature increase rate of 10° C./min, and the peak top temperature on the lowest temperature side of the DTA is determined as the condensation reaction temperature (T° C.) of compound (A).
(2) When a mixture of two or more compounds is used as compound (A), the mixture is subjected to TG-DTA analysis in a nitrogen gas atmosphere by increasing the temperature from 40° C. at a temperature increase rate of 10° C./min, and the peak top temperature on the lowest temperature side of the DTA is determined as the condensation reaction temperature (T° C.) of compound (A) (a mixture of two or more compounds).
(3) However, when the compound (A) as one type of compound or a mixture of two or more types of compounds contains impurities such as a solvent, moisture, or hydration water, the DTA peak (sometimes called the impurity peak) associated with the elimination of the impurity may be observed at a temperature lower than the condensation reaction temperature. In such a case, the above-mentioned impurity peak is ignored and the condensation reaction temperature of the compound (A) is determined. Usually, the above-mentioned impurity peak is ignored and the lowest DTA peak top temperature is determined as the condensation reaction temperature of the compound (A).

The heating temperature of compound (A) to obtain a soluble carbon material is preferably 200°C to 500°C, more preferably 220°C to 400°C, even more preferably 230°C to 350°C, and most preferably 250°C to 300°C. By adjusting the heating temperature of compound (A) to within the above range, a soluble carbon material having superior solubility in a solvent or a soluble carbon material having a more precisely controlled structure can be produced more easily under milder conditions.

The heating time of compound (A) to obtain a soluble carbon material is preferably 0.1 to 120 hours, more preferably 0.5 to 100 hours, even more preferably 1 to 50 hours, and most preferably 2 to 24 hours. By adjusting the heating time within the above range, a soluble carbon material having superior solubility in a solvent or a soluble carbon material having a more precisely controlled structure can be produced more easily under milder conditions.

<1-2-2-1. Compound (A)>
In the second embodiment, the compound (A) is preferably a solid at 23° C. and has a melting point. By having a melting point, the compound (A) melts during the firing process and the reaction between molecules proceeds smoothly. If the compound (A) does not have a melting point, it will not melt during the firing process, so the positions of the molecules will be fixed, and it will be difficult to promote reactions between the molecules, making it difficult to convert the compound (A) into a carbon material. This promotes the condensation reaction, suppresses the decomposition reaction, and improves the solubility of the resulting soluble carbon material in a solvent (for example, more components are dissolved in the solvent, and more types of solvents can be used). (or increase).

It is preferable that the skeleton of compound (A) that does not contribute to condensation is an aromatic structure. By having an aromatic skeleton, the carbon component of the obtained soluble carbon material can be more stable. Examples of such aromatic structures are aromatic structures consisting of carbon atoms such as benzene and naphthalene; heteroaromatic structures consisting of carbon atoms and heteroatoms (such as nitrogen and oxygen) such as pyridine, pyrimidine, furan, and thiophene; and among these, aromatic structures and heteroaromatic structures having a six-membered ring structure such as benzene and pyridine are more preferable.

The molecular weight of compound (A) may be any appropriate molecular weight within a range that does not impair the effects of the present invention. In order to better express the effects of the present invention, such a molecular weight is preferably 500 or less, more preferably 75 to 450, even more preferably 80 to 400, and most preferably 100 to 350.

The condensation reaction temperature of compound (A) may be any appropriate temperature within a range that does not impair the effects of the present invention. In order to more effectively exert the effects of the present invention, the condensation reaction temperature is preferably 450°C or less, more preferably 400°C or less, even more preferably 200°C to 370°C, and particularly preferably 250°C to 350°C.

When compound (A) is subjected to TG-DTA analysis under nitrogen gas atmosphere with a temperature rise condition of 10°C/min from 40°C, the weight ratio (M500/M50) of the weight M500 at a temperature of 500°C to the initial weight M50 at a temperature of 50°C is preferably 0.2 or more, more preferably 0.2 to 0.9, and most preferably 0.3 to 0.8, in order to further exert the effects of the present invention. By using compound (A) whose weight ratio (M500/M50) falls within the above range, a sufficient amount of soluble carbon material can be obtained.

[1-2-2-1-1. Preferred embodiment 1 of compound (A)]
The first embodiment of the compound (A) is an aromatic compound that is decomposed by heating to generate radicals on the aromatic ring. The aromatic compound having radicals on the aromatic ring can undergo a condensation reaction between the same molecules and/or different molecules to become a soluble carbon material.

The aromatic compound that decomposes when heated to generate radicals on the aromatic ring is preferably an aromatic compound that generates a gas (a gas that is in a gaseous state at room temperature and normal pressure) when heated.

As for aromatic compounds that generate gas when heated, the explanation in the above section [1-1-2-1-1. Preferred embodiment 1 of compound (A)] may be used.

Aromatic compounds that decompose by heating to generate radicals on aromatic rings are compounds that have decomposability by heating, and at least a part of the skeleton is dissociated and decomposed to generate gas molecules (preferably at least one selected from CO, CO ₂ , N ₂ , O ₂ , H ₂ , and NO ₂ ), and radicals are generated on the remaining aromatic ring. By using such aromatic compounds, a reaction occurs only by the decomposition of the compound itself without the need for a reaction catalyst, so that by-products of chemical reactions and reaction catalysts can be prevented from being present in the carbon material and becoming fatal impurities, and a higher quality soluble carbon material can be obtained. In addition, by using such aromatic compounds, a soluble carbon material can be obtained in a relatively mild temperature environment without using a flammable gas. In addition, such aromatic compounds can have high reactivity without the need for a catalyst.

[1-2-2-1-2. Another preferred embodiment 2 of compound (A)]
Another preferred embodiment 2 of the compound (A) is a compound in which one neutral molecule is formed and eliminated from two or more groups by a condensation reaction. In this embodiment 2, one compound may have two or more groups, or two or more compounds may combine their respective groups to form two or more groups. Such a compound (A) can undergo a condensation reaction between the same molecules and/or between different molecules to become a soluble carbon material.

For the condensation reaction, the explanation in the above section [1-1-2-1-2. Another preferred embodiment 2 of compound (A)] may be used.

[1-2-2-1-3. Further preferred embodiment 3 of compound (A)]
Yet another preferred embodiment 3 of the compound (A) is a form in which both the embodiment 1 and the embodiment 2 are simultaneously adopted. That is, the embodiment 3 is an aromatic compound that is decomposed by heating to generate radicals on an aromatic ring, and is a compound in which one neutral molecule is formed and eliminated from two or more types of groups by a condensation reaction. Such a compound (A) can undergo a condensation reaction between the same molecules and/or between different molecules to become a soluble carbon material.

For embodiment 3, the explanation in the above section [1-1-2-1-3. Further preferred embodiment 3 of compound (A)] may be used.

<1-2-3. Other processes>
In a preferred embodiment 2 of the lubricating filler, after the mixing step (I), preferably
(1) a solvent removal step (IIa) of removing at least a portion of the solvent (S);
(2) a soluble carbon material removal step (IIb) of removing at least a portion of the soluble carbon material;
(3) a heating step (III) of further heating;
(4) an inorganic particle removing step (IV) of removing the inorganic particle portion;
The compound includes at least one selected from the group consisting of:

In the second embodiment, after the mixing step (I), in addition to the above steps (IIa), (IIb), (III), and (IV), any appropriate step may be included within a range that does not impair the effects of the present invention. Such a step may be, for example, a purification step. For example, the purification step may be a step of washing the object to be purified with any appropriate solvent. Although such a solvent may be a recovered solvent, a fresh solvent is preferable in terms of improving the washing effect. Moreover, washing may be performed once or multiple times, such as two or more times. Note that such washing may be performed, for example, in the above steps (IIa), (IIb), (III), and (IV).

When embodiment 2 includes at least one step selected from the group consisting of a solvent removal step (IIa), a soluble carbon material removal step (IIb), a heating step (III), and an inorganic particle removal step (IV), the order of these steps can be appropriately set depending on the desired form of the lubricating filler.

In the case where the target lubricating filler is a lubricating filler (typically an "organic-inorganic composite" to be described later) having an inorganic particle portion and a carbon material portion (either the carbon material portion is present on the surface of the inorganic particle portion by strongly interacting with the outermost surface of the inorganic particle portion, or the carbon material portion and the carbon material portion that can be removed by the soluble carbon material removal step (IIb)), after the mixing step (I), preferably, a solvent removal step (IIa) is performed, and further, if necessary, a soluble carbon material removal step (IIb) may be performed.

When the target lubricating filler is a lubricating filler (typically a "core-shell particle" to be described later) having an inorganic particle portion and a carbon material portion (substantially only the carbon material portion that strongly interacts with the outermost surface of the inorganic particle portion and exists on the surface of the inorganic particle portion), after the mixing step (I), preferably, a solvent removal step (IIa) is performed, and further, a soluble carbon material removal step (IIb) is performed.

When the target lubricating filler is a lubricating filler in which the carbon material portion is highly carbonized (typically, the "highly carbonized core-shell particles" described below), after the mixing step (I), preferably, a solvent removal step (IIa) is performed, followed by a soluble carbon material removal step (IIb), and then a heating step (III).

<1-2-3-1. Solvent removal step (IIa)>
As described above, the mixing step (I) typically produces a lubricating filler (typically, the "organic-inorganic composite" described below) having an inorganic particle portion and a carbon material portion (either the carbon material portion is present on the inorganic particle surface by strongly interacting with the outermost surface of the inorganic particle, or the carbon material portion and the carbon material portion that can be removed by the soluble carbon material removal step). This lubricating filler typically contains a solvent (S) immediately after the mixing step (I). That is, this lubricating filler can typically be in the form of a dispersion.

The lubricating filler thus obtained (typically, the "organic-inorganic composite" described below) may be subjected to a solvent removal step (IIa) in which at least a portion of the solvent (S) is removed.

At least a portion of the solvent (S) is removed by the solvent removal step (IIa). Typically, substantially all of the solvent (S) is removed in the solvent removal step (IIa).

In the solvent removal step (IIa), any suitable solvent removal means may be used to remove at least a portion of the solvent (S) as long as it does not impair the effects of the present invention. Examples of such solvent removal means include distillation and dialysis.

<1-2-3-2. Soluble carbon material removal step (IIb)>
In the second embodiment, after the mixing step (I), a soluble carbon material removing step (IIb) of removing at least a portion of the soluble carbon material may be carried out.

At least a portion of the soluble carbon material is removed by the soluble carbon material removal step (IIb). Typically, in the soluble carbon material removal step (IIb), at least a portion of the carbon material portion that can be removed by the soluble carbon material removal step (IIb) is removed, other than the carbon material portion that strongly interacts with the outermost surface of the inorganic particle portion and is present on the surface of the inorganic particle portion. Typically, substantially all of the carbon material portion that can be removed by the soluble carbon material removal step (IIb) is removed.

In the soluble carbon material removal step (IIb), any suitable soluble carbon material removal means may be used as the means for removing at least a portion of the soluble carbon material, as long as the effect of the present invention is not impaired. Examples of such soluble carbon material removal means include washing with any suitable solvent. Washing can be achieved by dissolving the soluble portion with a suitable solvent, followed by filtration or centrifugation. Such a solvent may be a recovered solvent, but a fresh solvent is preferred in terms of increasing the washing effect. Washing may be performed once, or multiple times (two or more times).

<1-2-3-3. Heating process (III)>
In the second embodiment, the mixing step (I) may be followed by a heating step (III).

The heating step (III) typically results in the carbon material portion being highly carbonized.

The specific heating temperature in the heating step (III) is preferably 500°C to 3000°C, more preferably 600°C to 2500°C, and most preferably 700°C to 2000°C. By adjusting the heating temperature in the heating step (III) to within the above range, the carbon material portion can be effectively highly carbonized. The above temperature is preferably equal to or lower than the heat resistance temperature of the inorganic particles.

The heating time in the heating step (III) is preferably 0.1 to 120 hours, more preferably 0.5 to 100 hours, even more preferably 1 to 50 hours, and most preferably 2 to 24 hours. By adjusting the heating time to within the above range, the carbon material portion can be effectively highly carbonized.

<1-2-3-4. Inorganic particle removal step (IV)>
In the second embodiment, the mixing step (I) may be followed by an inorganic particle removing step (IV).

At least a portion of the inorganic particle portion is removed by the inorganic particle removal step (IV). Typically, substantially all of the inorganic particle portion is removed by the inorganic particle removal step (IV).

In the inorganic particle removal step (IV), any suitable inorganic particle removal means may be used as a means for removing at least a portion of the inorganic particle portion, as long as the effect of the present invention is not impaired. Examples of such inorganic particle removal means include treatment with any suitable solvent. For example, when the inorganic particle portion is an inorganic portion, a method of removing it with a solvent that can dissolve the inorganic portion without dissolving the carbon material portion is included. Although not particularly limited, a solvent having the above-mentioned solubility characteristics is preferable, and an aqueous solvent is preferable. The reason why an aqueous solvent is preferable in this way is that the carbon material portion contained in the lubricating filler produced by the production method of the present invention is difficult to dissolve in water, while the inorganic portion is often soluble in water (especially acidic water or basic water). Examples of aqueous solvents include acidic aqueous solutions such as sulfuric acid, hydrochloric acid, and nitric acid; basic aqueous solutions such as sodium hydroxide, potassium hydroxide, and ammonia; and the like. In addition, in the inorganic particle removal step (IV), the temperature is not particularly limited, but is preferably 0°C to 150°C, and more preferably 20°C to 100°C, in order to effectively express the solubility characteristics of the aqueous solvent. Furthermore, the physical treatment in the inorganic particle removal step (IV) is not particularly limited, but from the viewpoint of effectively expressing the removability, standing, stirring, ultrasonic treatment, and shear operation are preferable, and stirring, ultrasonic treatment, and shear operation are more preferable.

<1-2-4. Details of the lubricating filler according to embodiment 2>
A second preferred embodiment of the lubricating filler is a lubricating filler obtained by a method including a mixing step (I) of mixing a soluble carbon material that is soluble in a solvent (S) and inorganic particles in the solvent (S).

The lubricating filler according to the second embodiment can be used for various applications by controlling the thickness of the carbon material portion. For example, the thickness of the carbon material portion can be as follows:
(Aspect 1) The film thickness of the carbon material portion in the lubricating filler obtained by removing all carbon material portions other than the carbon material portions that strongly interact with the outermost surfaces of the inorganic particle portions and are present on the surfaces of the inorganic particles in the soluble carbon material removal step (IIb),
(Aspect 2) The film thickness of the carbon material portion of the lubricating filler in a state in which all or a part of the carbon material portion of the lubricating filler remains,
Examples include:

More specifically, the carbon material portion in the above (Aspect 1) is a carbon material portion that strongly interacts with the outermost surface of the inorganic particle, obtained by removing all carbon material (typically, soluble carbon material) other than the carbon material portion that strongly interacts with the outermost surface of the inorganic particle portion and is present on the inorganic particle surface in the soluble carbon material removal step (IIb). The film thickness of such a carbon material portion is thin, and although it depends on the structure of the carbon material portion, it is preferably 0.3 nm to 10 nm, and more preferably 0.4 nm to 3 nm. By controlling the film thickness of the carbon material portion within this range, the carbon material portion that strongly interacts with the inorganic particle can be fully utilized for various applications.

In the above (Aspect 1), typically, the film thickness of the carbon material portion is thin, but it is possible to adjust the thickness without any upper limit by adopting an appropriate soluble carbon material removal method in the soluble carbon material removal step (IIb).

The film thickness of the carbon material portion in the above (Aspect 2) is typically thicker than the film thickness of the carbon material portion in the above (Aspect 1), but in order to better function as a carbon material film, it is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 10 μm or less, and most preferably 1 μm or less. In the above (Aspect 2), if the film thickness of the carbon material portion is controlled within this range, it can fully function as a film.

The film thickness of the carbon material portion can be appropriately controlled by the type of raw material compound (e.g., soluble carbon material, more specifically, typically compound (A)) used in the manufacturing method of the lubricating filler and the manufacturing conditions.

The film thickness of such carbon material parts can be confirmed by various analytical methods. Examples of such analytical methods include a method of direct observation using an electron microscope (Method A) and a method of estimating the amount of carbon calculated from elemental analysis or thermogravimetric analysis from the macroscopic surface area of the inorganic particle part (excluding the surface area of a microstructure that organic molecules cannot penetrate) and the density of the carbon material part (Method B).

More specifically, the above (Method A) can be exemplified by a method in which a cross section of a sample of lubricating filler is observed using a transmission electron microscope or a scanning electron microscope, preferably a transmission electron microscope or a scanning electron microscope equipped with an energy dispersive X-ray analyzer.

In the above (Method B), the macroscopic surface area of the inorganic particle portion can be estimated from the shape of the lubricating filler sample and the shape of the inorganic particle portion contained therein.

In the above (Method A), for example, when the sample is a particle, it is preferable to measure the thickness at three or more points for each particle contained in the sample and use the simple average value as the film thickness of the particle, and more preferably, to measure the film thickness of 10 or more particles and use the simple average value as the average film thickness of the sample. It is preferable that the film thickness (average film thickness) obtained in this way is within the desired film thickness range to be controlled as described above.

In the above (Method B), the analyzed film thickness can be regarded as the average film thickness of the sample. It is preferable that the film thickness analyzed by this (Method B) falls within the desired film thickness range to be controlled, for example, as described above.

Examples of lubricating fillers according to embodiment 2 include organic-inorganic composites, core-shell particles, and highly carbonized core-shell particles.

<1-2-4-1. Organic-inorganic composite>
The organic-inorganic composite can typically be obtained by a mixing step (I) of mixing a soluble carbon material that is soluble in a solvent (S) with inorganic particles in the solvent (S).

As a mixing method, any appropriate mixing method may be adopted as long as it does not impair the effects of the present invention. For example, such a mixing method may include a method in which the soluble carbon material, inorganic particles, and solvent (S) are mixed by any appropriate method (e.g., ultrasonic treatment, etc.). In this case, the soluble carbon material and inorganic particles may be mixed after any appropriate treatment (e.g., crushing, crushing, pulverization, etc.).

When mixing, any suitable other components other than the soluble carbon material, inorganic particles, and solvent (S) may be included as long as they do not impair the effects of the present invention.

The blending ratio of the soluble carbon material to the inorganic particles is preferably 0.01% by mass to 1,000,000% by mass, more preferably 0.1% by mass to 100,000% by mass, and particularly preferably 1% by mass to 1,000% by mass, relative to 100% by mass of the inorganic particles. If the blending ratio of the soluble carbon material to the inorganic particles is within the above range, an organic-inorganic composite having a more precisely controlled structure can be produced more easily under milder conditions. The blending ratio of these soluble carbon materials to the inorganic particles can be adjusted arbitrarily depending on the physical properties of the desired organic-inorganic composite. For example, by adjusting the blending ratio of the soluble carbon material to the inorganic particles, the physical properties and form of the obtained organic-inorganic composite (for example, solubility in a solvent, the shape of the carbon material portion or the inorganic portion (particulate or non-particulate), the size of the carbon material portion or the inorganic particle portion, etc.) can be controlled.

Soluble carbon materials are typically obtained by heating a compound (A) that undergoes a condensation reaction between identical molecules and/or different molecules upon heating.

The soluble carbon material may be one type or two or more types.

There may be only one type of inorganic particles, or two or more types.

For soluble carbon materials, the explanation in section 1-2-2. Soluble carbon materials may be used.

For inorganic particles, the explanation in section 1-2-1. Inorganic particles may be used.

The organic-inorganic composite includes a carbon material portion and an inorganic particle portion. The carbon material portion includes a soluble carbon material, and typically includes (i) a carbon material portion that strongly interacts with the outermost surface of the inorganic particle portion and is present on the surface of the inorganic particle portion, and (ii) a carbon material portion that can be removed by the soluble carbon material removal step (IIb).

As shown in FIG. 1, the organic-inorganic composite 100 is typically a composite in which a plurality of inorganic particles 20 are dispersed in a carbon material 10 as a matrix, and at the interface between the carbon material 10 and the inorganic particles 20, there is a carbon material region (carbon material bonded region) 30 formed by bonding the carbon material with a functional group present on the surface of the inorganic particles 20. Then, for example, when the carbon material is soluble in a solvent, by treating the organic-inorganic composite 100 with a solvent that dissolves the carbon material, as shown in FIG. 2, a core-shell particle (core part: inorganic oxide particle, shell part: carbon material bonded region) 200 in which the surface of the inorganic particle 20 is coated with a carbon material bonded region (region that is not dissolved by the solvent) 30 can be obtained. By removing the inorganic particle 20 as the core part from the core-shell particle 20 thus obtained, hollow carbon microparticles having a carbon material can be obtained.

The content of the carbon material portion in the organic-inorganic composite is preferably 0.01% by mass to 99.99% by mass, and particularly preferably 0.1% by mass to 99.9% by mass. If the content of the carbon material portion in the organic-inorganic composite is within the above range, the organic-inorganic composite can be industrially produced under mild conditions. The content of these carbon material portions can be easily adjusted to any desired ratio by the soluble carbon material removal step (IIb) or the like, depending on the desired physical properties.

The content of the inorganic particle portion in the organic-inorganic composite is preferably 0.01% by mass to 99.99% by mass, and particularly preferably 0.1% by mass to 99.9% by mass. If the content of the inorganic particle portion in the organic-inorganic composite is within the above range, the organic-inorganic composite can be industrially produced under mild conditions. The content of these inorganic particle portions can be easily adjusted to any desired ratio by the soluble carbon material removal step (IIb) or the like, depending on the desired physical properties.

The organic-inorganic composite has an oxidation onset temperature, indicated by the DTA rise temperature, of preferably 200°C or higher, more preferably 250°C or higher, and most preferably 300°C or higher, when TG-DTA analysis is performed in an air atmosphere under a temperature rise condition of 10°C/min from 40°C. If the oxidation onset temperature, indicated by the DTA rise temperature, when TG-DTA analysis is performed in an air atmosphere under a temperature rise condition of 10°C/min from 40°C, is within the above range, the lubricating filler of the present invention has high oxidation stability, that is, the structure is controlled and the skeletal structure is maintained, so that the oxidation resistance (decomposition resistance) is high. If cleavage of the skeleton occurs such that a C=O bond is generated, the stability of the skeleton may decrease, and the oxidation resistance (decomposition resistance) may decrease.

The organic-inorganic composite includes a carbon material portion and an inorganic particle portion, and the carbon material portion includes a soluble carbon material, typically including (i) a carbon material portion that strongly interacts with the outermost surface of the inorganic particle portion and is present on the surface of the inorganic particle portion, and (ii) a carbon material portion that can be removed by the soluble carbon material removal step (IIb).

The presence of carbon components in the carbon material portion can be easily confirmed by C1sXPS analysis. In addition, the carbon material portion preferably has a honeycomb structure (graphene structure) derived from benzene rings within its structure. The presence or absence of the graphene structure can be confirmed by Raman spectroscopy analysis.

The carbon material portion has a total content of impurity metal components, preferably 0.1 atomic % or less, more preferably 0.01 atomic % or less, and particularly preferably substantially zero, relative to 100 atomic % of carbon atoms. These can be confirmed by analyzing the carbon material portion using X-ray fluorescence elemental analysis (XRF). In addition, when the lubricating filler (in this item, the organic-inorganic composite) is analyzed using X-ray fluorescence elemental analysis (XRF), the content of metal components other than the metal components contained in the inorganic particle portion constituting the lubricating filler (in this item, the organic-inorganic composite) is preferably 0.1 atomic % or less, more preferably 0.01 atomic % or less, and particularly preferably substantially zero, relative to 100 atomic % of carbon atoms. For example, when a lubricating filler (organic-inorganic composite in this section) in which the inorganic particle portion is alumina is analyzed by X-ray fluorescence elemental analysis (XRF), if the only metal component contained in the alumina is aluminum, the content of metal components other than aluminum is preferably 0.1 atomic % or less, more preferably 0.01 atomic % or less, and particularly preferably substantially zero, relative to 100 atomic % of carbon atoms.

The carbon material portion must contain carbon as a constituent element, and may contain elements other than carbon. Such elements other than carbon are preferably at least one element selected from oxygen, hydrogen, nitrogen, sulfur, fluorine, chlorine, bromine, and iodine, more preferably at least one element selected from oxygen, hydrogen, nitrogen, and sulfur, even more preferably at least one element selected from oxygen, hydrogen, and nitrogen, and particularly preferably at least one element selected from oxygen and hydrogen. When the total amount of elements other than hydrogen among the elements constituting the carbon material portion is taken as 100 atomic %, carbon is preferably 60 atomic % or more, more preferably 70 atomic % or more, and even more preferably 75 atomic % or more. In addition, elements other than carbon are preferably 10 atomic % or more. When the ratio of each element falls within this range, it is possible to exhibit good solubility even though it is a carbon material portion. These can be confirmed by quantifying the carbon material portion by X-ray photoelectron spectroscopy (C1sXPS). In addition, when the lubricating filler (in this item, the organic-inorganic composite) is quantified by X-ray photoelectron spectroscopy (C1sXPS), when the total amount of elements other than the elements contained in the inorganic part constituting the lubricating filler (in this item, the organic-inorganic composite) is taken as 100 atomic %, carbon is preferably 60 atomic % or more, more preferably 70 atomic % or more, and even more preferably 75 atomic % or more. In addition, elements other than carbon are preferably 10 atomic % or more.

The carbon material portion contained in the organic-inorganic composite typically includes (i) a carbon material portion that is present on the surface of the inorganic particle portion by strongly interacting with the outermost surface of the inorganic particle portion, and (ii) a carbon material portion that can be removed by the soluble carbon material removal step (IIb).

Both the carbon material portion (i) and the carbon material portion (ii) above may be soluble in a solvent. Here, the carbon material portion (i) above is present on the surface of the inorganic particle portion by strongly interacting with the outermost surface of the inorganic particle portion, and therefore tends to have a lower solubility in the solvent than the carbon material portion (ii) above. In addition, the carbon material (ii) above is a carbon material portion that can be removed by the soluble carbon material removal step (IIb), and tends to have a higher solubility in the solvent. Note that the "solvent" referred to here does not have to be the same as the solvent (S) used in the mixing step (I).

As an embodiment in which the carbon material portion contained in the organic-inorganic composite is soluble in a solvent, the following embodiments can be preferably adopted.
(Embodiment 1) An embodiment in which the entire carbon material portion is soluble in a solvent, that is, an embodiment in which the carbon material portion is composed only of a component (component A) that is soluble in a solvent.
(Embodiment 2) An embodiment in which a part of the carbon material portion dissolves in a solvent, that is, an embodiment in which the carbon material portion comprises a component (component A) that dissolves in a solvent and a component (component B) that does not dissolve in a solvent.

The carbon material portion contained in the organic-inorganic composite is more preferably soluble in a solvent as described above (embodiment 2). That is, the component that dissolves in the solvent (component A) is the carbon material portion that can be removed by the soluble carbon material removal step (IIb), and the component that does not dissolve in the solvent (component B) is the carbon material portion that strongly interacts with the outermost surface of the inorganic particle portion and is present on the surface of the inorganic particle portion.

As the solvent, any suitable solvent may be used as long as it does not impair the effects of the present invention. Such solvents preferably include N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, methanol, ethanol, 2-propanol, butanol, chloroform, dichloromethane, etc. That is, an embodiment in which there is a component that dissolves in at least one solvent selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, methanol, ethanol, 2-propanol, butanol, chloroform, and dichloromethane is preferable. More preferably, the composition contains a component that dissolves in at least one solvent selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, and chloroform; even more preferably, the composition contains a component that dissolves in at least one solvent selected from the group consisting of N,N-dimethylformamide and N-methylpyrrolidone; and particularly preferably, the composition contains a component that dissolves in N-methylpyrrolidone.

The solvent may consist of only one type of solvent, or may be a mixture of two or more types of solvents.

One embodiment in which the carbon material portion is soluble in a solvent is, for example, an embodiment in which the carbon material portion includes a carbon-based compound that is soluble in a solvent.

As a method for determining whether or not a compound is soluble in a solvent, for example, an organic-inorganic complex is mixed with a solvent so that the concentration is 0.001% by mass, and then ultrasonic treatment is performed for 1 hour. When the resulting liquid is passed through a PTFE filter paper (pore size 0.45 μm), it can be determined whether or not the liquid that passed through the filter paper contains a carbon-based compound. If the liquid that passed through the filter paper contains a carbon-based compound, it is determined that the carbon material portion contains a carbon-based compound that is soluble in the solvent. As the PTFE filter paper, for example, a GL Chromatodisc (Model 13P) manufactured by GL Sciences Inc. can be used.

The carbon material portion preferably (i) exhibits a peak in the G band (generally in the range of 1550 cm ^-1 to 1650 cm ^-1 ) in a Raman spectrum obtained by Raman spectroscopy. Therefore, when the carbon material portion has a peak in the G band (generally in the range of 1550 cm ^-1 to 1650 cm ^-1 ) in a Raman spectrum obtained by Raman spectroscopy, it means that the carbon material portion has a graphene structure or a structure similar to a graphene structure. If the G band is strong and sharp, it can be said that the carbon material portion has a cleaner graphene structure or a structure similar to a graphene structure.

The carbon material portion preferably (ii) exhibits a peak in the D band (generally in the range of 1300 cm ^-1 to 1400 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy. The carbon material portion having a structure derived from defects in the graphene structure exhibits a peak in the D band (generally in the range of 1300 cm ^-1 to 1400 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy. Therefore, the carbon material portion having a peak in the D band (generally in the range of 1300 cm ^-1 to 1400 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy means that the carbon material portion contains a functional group, has a structure derived from defects in the graphene structure, or has a structure similar to a structure derived from defects in the graphene structure. If the intensity of the D band is low, it can be said that the lubricating filler has a cleaner graphene structure or a structure similar to a graphene structure. In addition, the fact that the D band can be confirmed means that the lubricating filler obtained by the manufacturing method of the present invention has a functional group, which can increase the solubility in a solvent.

The carbon material portion preferably (i) exhibits a peak in the G band (generally in the range of 1550 cm ^-1 to 1650 cm ^-1 ) in a Raman spectrum obtained by Raman spectroscopy, and further (ii) exhibits a peak in the D band (generally in the range of 1300 cm ^-1 to 1400 cm ^-1 ) in a Raman spectrum obtained by Raman spectroscopy.

The carbon material portion preferably (iii) exhibits a peak in the G' band (generally in the range of 2650 cm ^-1 to 2750 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy. Therefore, when the carbon material portion has a peak in the G' band (generally in the range of 2650 cm ^-1 to 2750 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy, it means that the carbon material portion has a graphene structure or a structure similar to a graphene structure. The intensity of the G' band is strongest when the graphene structure is one layer, and gradually decreases as the number of stacked layers of the graphene structure increases. However, even if the intensity of the G' band gradually decreases as the number of stacked layers of the graphene structure increases, the peak can be observed. Therefore, when the G' band has a peak, it can be said that the carbon material portion has a graphene structure or a structure similar to a graphene structure. The G' band is sometimes called a 2D band.

The carbon material portion preferably (i) exhibits a peak in the G band (generally in the range of 1550 cm ^-1 to 1650 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy, (ii) exhibits a peak in the D band (generally in the range of 1300 cm ^-1 to 1400 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy, and (iii) exhibits a peak in the G' band (generally in the range of 2650 cm ^-1 to 2750 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy.

The carbon material portion preferably exhibits a peak in the D+D' band (generally in the range of 2800 cm ^-1 to 3000 cm ^-1 ) in the Raman spectrum obtained by (iv) Raman spectroscopy. A carbon material having a structure derived from defects in a graphene structure exhibits a peak in the D+D' band (generally in the range of 2800 cm ^-1 to 3000 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy. Therefore, when the carbon material portion has a peak in the D+D' band (generally in the range of 2800 cm ^-1 to 3000 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy, it means that the carbon material portion contains a functional group or has a structure derived from defects in the graphene structure or a structure similar to a structure derived from defects in the graphene structure. If the intensity of the D+D' band is low, it can be said that the carbon material has a cleaner graphene structure or a structure similar to a graphene structure. The D+D' band may also be called the D+G band. Furthermore, the fact that the D+D' band can be confirmed also means that the lubricating filler obtained by the manufacturing method of the present invention has a functional group, which can enhance the solubility in a solvent.

The carbon material portion preferably (i) exhibits a peak in the G band (generally in the range of 1550 cm ^-1 to 1650 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy, (ii) exhibits a peak in the D band (generally in the range of 1300 cm ^-1 to 1400 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy, (iii) exhibits a peak in the G' band (generally in the range of 2650 cm ^-1 to 2750 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy, and (iv) exhibits a peak in the D+D' band (generally in the range of 2800 cm ^-1 to 3000 cm ^-1 ) in the Raman spectrum obtained by Raman spectroscopy.

The carbon material portion preferably includes a carbon-based compound that is soluble in the solvent.

In one embodiment, the carbon material portion includes, for example, a carbon-based compound that (i) exhibits a peak in the G band (generally in the range of 1550 cm ^-1 to 1650 cm ^-1 ) in a Raman spectrum obtained by Raman spectroscopy, and (ii) exhibits a peak in the D band (generally in the range of 1300 cm ^-1 to 1400 cm ^-1 ) in a Raman spectrum obtained by Raman spectroscopy, and is soluble in a solvent.

When the carbon material portion contains functional groups and has defects in part of the graphene structure, these defects can contribute to the solubility of the carbon material portion in a solvent.

As described above, unlike conventionally known carbon materials, the carbon material portion has a graphene structure or a structure similar to a graphene structure, and the solubility of the carbon material portion in a solvent is superior (for example, more components of the carbon material portion dissolve in the solvent, or more types of solvents in which the carbon material portion can dissolve are available).

The molecular weight of the carbon-based compound contained in the carbon material portion is preferably 1000 to 1300000, more preferably 5000 to 1000000, even more preferably 10000 to 700000, particularly preferably 15000 to 500000, and most preferably 20000 to 300000. If the molecular weight of the carbon-based compound contained in the carbon material portion is within the above range, the solubility of the carbon material portion in the solvent is more excellent (for example, more components of the carbon material portion dissolve in the solvent, or more types of solvents in which the carbon material portion can be dissolved). If the molecular weight of the carbon-based compound contained in the carbon material portion exceeds 1300000, the solubility of the carbon material portion in the solvent may be poor. If the molecular weight of the carbon-based compound contained in the carbon material portion is less than 1000, the characteristics of the carbon material portion may be weakened. These molecular weights can be analyzed by the method described below.

The content of the carbon-based compound in the carbon material portion is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, even more preferably 90% by mass to 100% by mass, particularly preferably 95% by mass to 100% by mass, and most preferably substantially 100% by mass. If the content of the carbon-based compound in the carbon material portion is within the above range, the solubility of the carbon material portion in the solvent is more excellent (for example, more components of the carbon material portion dissolve in the solvent, or more types of solvents in which the carbon material portion can dissolve).

The carbon material portion preferably exhibits a peak in the range of 20° to 30° in an XRD spectrum chart obtained by XRD analysis. In other words, in one preferred embodiment, the carbon material portion has a structure in which graphene structures are stacked (graphene stacked structure). By having a stacked structure, the carbon material portion can become stronger and more stable.

More preferred forms of the carbon material portion are those that have any one of the above forms (i) to (iv) or a combination of forms (i) and (ii), (i), (ii) and (iii), (i), (ii), (iii) and (iv) in the Raman spectrum obtained by Raman spectroscopy, and that show a peak within the range of 20° to 30° in the XRD spectrum chart obtained by XRD analysis.

The organic-inorganic composite may be in any suitable state. For example, it may be a dispersion in which it is dispersed in a solvent, or it may be a solid (e.g., particulate, fibrous, thin film, plate, etc.) from which the solvent has been removed.

The organic-inorganic composite may preferably exist in a bulk state. In general, the properties of a substance in a bulk state are the inherent properties of that substance. That is, for a substance in a bulk state, the basic properties of that substance, such as the boiling point, melting point, viscosity, and density, can be determined. The physical properties of a substance refer to the properties of the bulk portion. Examples of bulk states include particles, pellets, and films. Examples of the state in which particles exist include powder. As for the film, it is preferable that it is a free-standing film.

<1-2-4-2. Core-shell particles>
The core-shell particles are typically lubricating fillers having an inorganic particle portion and a carbon material portion (substantially only the carbon material portion that is present on the surface of the inorganic particle portion and strongly interacts with the outermost surface of the inorganic particle portion).

The core-shell particles are obtained by carrying out a soluble carbon material removal step (IIb) on a lubricating filler (typically an organic-inorganic composite) having an inorganic particle portion and a carbon material portion (including both a carbon material portion that strongly interacts with the outermost surface of the inorganic particle portion and exists on the surface of the inorganic particle portion, and a carbon material portion that can be removed by a soluble carbon material removal step (IIb)) obtained by carrying out a mixing step (I) and a solvent removal step (IIa) in the lubricating filler according to embodiment 2. In the soluble carbon material removal step (IIb), the organic-inorganic composite is treated with a solvent that dissolves the carbon material contained in the organic-inorganic composite. As a result, as shown in FIG. 2, a core-shell particle (core portion: inorganic particle, shell portion: carbon material binding region) 200 in which a carbon material binding region (a region that is not dissolved by the solvent) 30 is coated on the surface of the inorganic particle 20 can be obtained. Such a core-shell particle is a lubricating filler according to embodiment 2.

Examples of the solvent include N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, methanol, ethanol, 2-propanol, butanol, chloroform, dichloromethane, etc., and preferably N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, chloroform, more preferably N,N-dimethylformamide, N-methylpyrrolidone, and particularly preferably N-methylpyrrolidone.

<1-2-4-3. Highly carbonized core-shell particles>
The highly carbonized core-shell particles are typically lubricating fillers in which the carbon material portion of the core-shell particles is highly carbonized.

The highly carbonized core-shell particles are typically obtained by subjecting core-shell particles (core portion: inorganic particles, shell portion: carbon material bonding region) to a heating step (III) in the lubricating filler according to embodiment 2. This heating step (III) can highly carbonize the shell portion. This makes it possible to obtain highly carbonized core-shell particles (core portion: inorganic particles, shell portion: highly carbonized material). High carbonization can improve the strength and heat resistance of the obtained lubricating filler. The highly carbonized core-shell particles are the lubricating filler according to embodiment 2.

The heating temperature in the heating step (III) may be within a range that the inorganic particle portion of the core can withstand, but specific heating temperatures are preferably 500°C to 3000°C, more preferably 600°C to 2500°C, and most preferably 700°C to 2000°C. By adjusting the heating temperature in the heating step (III) to within the above range, the shell portion can be effectively highly carbonized.

The specific heating time in the heating step (III) is preferably 0.1 to 120 hours, more preferably 0.5 to 100 hours, even more preferably 1 to 50 hours, and most preferably 2 to 24 hours. By adjusting the heating time to within the above range, the shell portion can be effectively highly carbonized.

≪≪≪2. Lubricating composition≫≫≫
Lubricant compositions according to embodiments of the present invention include lubricant fillers according to embodiments of the present invention.

The lubricating composition according to an embodiment of the present invention may contain any other appropriate components as long as they do not impair the effects of the present invention, as long as they contain the lubricating filler according to an embodiment of the present invention.

Other components that may be included in the lubricating composition according to the embodiment of the present invention include, for example, a dispersion medium (also called a base oil; for example, water, an organic solvent, etc., including low-viscosity and high-viscosity ones), a dispersion stabilizer, a viscosity modifier, a viscosity index improver, a detergent dispersant, an antioxidant, an emulsifier, etc. In particular, with regard to the dispersion medium, tetraethylene glycol dimethyl ether, secondary alcohol ethoxylate, and liquid paraffin used in the friction test for the lubricating filler according to the embodiment of the present invention are examples, and any dispersion medium that exhibits low friction can be suitably used. For example, a dispersion medium that can disperse the lubricating filler (equivalent to an organic-inorganic composite) well and has low resistance that does not interfere with the rolling friction of the lubricating filler can be suitably used.

Specific examples of the dispersion medium include polyoxyalkylene dispersion mediums having polyoxyalkylene moieties in the molecule such as tetraethylene glycol dimethyl ether and softanol, which disperse the organic-inorganic composite well, plant essential oils having triglyceride moieties, mineral oils, and synthetic oils (hydrocarbon-based, ester-based, ether-based, silicone-based, etc.). Furthermore, even if the organic-inorganic composite is difficult to disperse in water, etc., these dispersion mediums can be used suitably as long as a layer of the lubricating filler can be formed at the sliding interface during sliding. In other words, even if the composition is difficult to disperse and difficult to form a stable dispersion, it can be used by making it into a temporary dispersion by shaking it vigorously before use. In addition, the dispersion medium can be used suitably whether it has a low viscosity or a high viscosity (for example, lubricating oil or grease, etc.). Furthermore, as the dispersion medium, one that has volatility is also preferred. For example, by using a solvent with a low boiling point, the lubricating filler can be formed into a film on the sliding part in the form of paint, spray, aerosol, etc. and dried. After drying, the non-volatile dispersion medium remains as a new lubricating composition, so that the film exhibits good friction characteristics.

The preferred concentration of the lubricating filler in the lubricating composition according to the embodiment of the present invention varies depending on the application and conditions of use. The lubricating filler according to the embodiment of the present invention can be used in various concentrations, and the effects of the present invention can be achieved at any concentration, but the concentration is preferably 0.01% by mass or more and 99% by mass or less, more preferably 0.05% by mass or more and 90% by mass or less, and even more preferably 0.1% by mass or more and 50% by mass or less. In addition, when a volatile component is present in the composition, the filler concentration in the lubricating composition according to the embodiment of the present invention is preferably such that the composition after evaporation falls within the above range.

The degree of carbonization of the carbon material layer on the surface of the lubricating filler according to the embodiment of the present invention can be adjusted by heating. By adjusting the degree of carbonization of the lubricating filler according to the embodiment of the present invention to an appropriate dispersion medium, the dispersibility can be adjusted. Even if the lubricating filler according to the embodiment of the present invention is difficult to disperse in a dispersion medium, it is possible to improve the dispersibility by appropriately applying a dispersion stabilizer (such as a surfactant).

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass". In this specification, "mass" may be read as "weight". However, in the parts related to C1sXPS in this specification, "%" means atomic %.
Ta.

<Friction test>
The friction test was performed under the following conditions, and the average value of the dynamic friction coefficient area in the forward path in each reciprocating sliding was taken as the average dynamic friction coefficient. The dispersion to be tested was prepared by adjusting the lubricating filler as a sample to a predetermined dispersion concentration using a dispersion medium.
Temperature: 25°C
Relative humidity: 50%
Testing machine: TL201 manufactured by Trinity Lab Co., Ltd.
Dispersion medium: Tetraethylene glycol dimethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd., hereinafter referred to as TEGD), secondary alcohol ethoxylate (manufactured by Nippon Shokubai, Softanol 120, hereinafter referred to as SOFT), or liquid paraffin (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., hereinafter referred to as PARA)
Substrate: SUS304
Contact: 10 mm x 10 mm SUS304 surface contact or 6 mm φ SUS304 point contact Load: 400 g (3.92 kPa for surface contact, 39.2 MPa for point contact)
Sliding distance: 10 mm
Sliding speed: 10 mm/sec. Number of sliding strokes: 1000 round trips (data acquisition time = 10 ms)

<Average particle size>
Inorganic particles were added to methanol to a concentration of 1% by mass, and dispersed for 10 minutes using an ultrasonic disperser to prepare a measurement sample. This sample was measured using a laser diffraction/scattering type particle size distribution measuring device (LA-920 manufactured by Horiba, Ltd.). The arithmetic mean value of the obtained volume-based particle size distribution was taken as the average particle size.

Example 1
10 g of spherical silica particles (manufactured by Nippon Shokubai) with an average particle size of 0.5 μm and 1 g of phloroglucinol (manufactured by Tokyo Kasei Kogyo Co., Ltd.) were dispersed and mixed in acetone by ultrasonic treatment, and then dried to obtain a mixture of spherical silica particles and phloroglucinol. This mixture was fired at 300° C. for 2 hours while stirring under a nitrogen atmosphere. The fired body obtained was repeatedly subjected to ultrasonic treatment and centrifugation in N,N-dimethylformamide (DMF) to remove excess carbon material. Thereafter, it was dried and fired at 700° C. for 2 hours under a nitrogen atmosphere to obtain a lubricating filler (1) in which the surface of the inorganic particles was coated with a carbon material. A friction test was performed with a dispersion concentration of 5% by mass (dispersion medium: TEGD, contact: SUS304 surface contact of 10 mm×10 mm).
The results are shown in Table 1 and FIG.

Example 2
The friction test was carried out in the same manner as in Example 1, except that the dispersion concentration was set to 20% by mass.
The results are shown in Table 1 and FIG.

Example 3
A lubricating filler (2) was obtained in the same manner as in Example 1, except that spherical silica particles (manufactured by Nippon Shokubai) having an average particle size of 1.0 μm were used instead of spherical silica particles (manufactured by Nippon Shokubai) having an average particle size of 0.5 μm. A friction test was performed with a dispersion concentration of 5 mass% (dispersion medium: TEGD, contact: 10 mm × 10 mm SUS304 surface contact).
The results are shown in Table 1 and FIG.

Example 4
The same procedure as in Example 3 was carried out except that the friction test was carried out with the dispersion concentration set to 20% by mass.
The results are shown in Table 1 and FIG.

Example 5
A lubricating filler (3) was obtained in the same manner as in Example 1, except that spherical silica particles (manufactured by Nippon Shokubai) having an average particle size of 2.5 μm were used instead of spherical silica particles (manufactured by Nippon Shokubai) having an average particle size of 0.5 μm. A friction test was performed with a dispersion concentration of 5 mass% (dispersion medium: TEGD, contact: 10 mm × 10 mm SUS304 surface contact).
The results are shown in Table 1 and FIG.

Example 6
The same procedure as in Example 5 was carried out except that the friction test was carried out with the dispersion concentration set to 20% by mass.
The results are shown in Table 1 and FIG.

Example 7
The same procedure as in Example 5 was carried out except that the friction test was carried out with the dispersion concentration set to 0.5% by mass.
The results are shown in Table 1 and FIG.

Comparative Example 1
A lubricating filler (C1) was obtained in the same manner as in Example 1, except that spherical silica particles (manufactured by Nippon Shokubai) having an average particle size of 0.2 μm were used instead of spherical silica particles (manufactured by Nippon Shokubai) having an average particle size of 0.5 μm. A friction test was performed with a dispersion concentration of 5 mass% (dispersion medium: TEGD, contact: 10 mm × 10 mm SUS304 surface contact).
The results are shown in Table 1 and FIG.

Comparative Example 2
The friction test was carried out in the same manner as in Comparative Example 1, except that the dispersion concentration was changed to 20% by mass.
The results are shown in Table 1 and FIG.

Example 8
The same procedures as in Example 5 were carried out except that the dispersion concentration was 5% by mass and the friction test was carried out (dispersion medium: TEGD, contact: 6 mmφ SUS304 point contact).
The results are shown in Table 1 and FIG.
These results show that the effect is also seen under point contact conditions, which are more pressurized conditions than surface contact.

Example 9
The same procedure as in Example 5 was repeated except that the dispersion medium was changed to Softanol 120.
The results are shown in Table 1 and FIG.

Example 10
The same procedure as in Example 5 was repeated except that the dispersion medium was liquid paraffin.
The results are shown in Table 1 and FIG.
Liquid paraffin is a highly hydrophobic dispersion medium in which inorganic particles are difficult to disperse, but it has been found that the present invention is effective even when liquid paraffin is used.

Example 11
The same procedure as in Example 5 was carried out except that the dispersion medium was water.
The results are shown in Table 1 and FIG.
Water is a dispersion medium that has strong polarity and makes it difficult for carbon-coated inorganic particles to disperse therein. However, it has been found that the present invention is effective even when water is used.

Example 12
In the same manner as in Example 6, a 20% TEGD dispersion of the lubricant filler (3) was prepared, and then a low boiling point solvent, dichloromethane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., boiling point 40 degrees), was added thereto to dilute the dispersion by a factor of 50. This diluted dispersion was sprayed onto a SUS304 substrate for friction testing using an organic solvent spraying spray, and dried, and then a friction test (dispersion medium: TEGD, contact: SUS304 surface contact of 10 mm x 10 mm) was similarly performed.
The results are shown in Table 1 and FIG.
By diluting with a low boiling point solvent, it became possible to spray the lubricating composition and form a thin film over a wide area. The thin film formed also exhibited the effects of the present invention and showed good friction characteristics.

[Reference Example 1]
As a reference example, particles not coated with carbon, i.e., spherical silica particles having an average particle diameter of 2.5 μm (manufactured by Nippon Shokubai), were used as they were, and a friction test was performed at a dispersion concentration of 5 mass% (dispersion medium: TEGD, contact: 10 mm × 10 mm SUS304 surface contact).
The results are shown in Table 1 and FIG.
It was found that even for particles without a carbon coating, the initial friction characteristics are good due to rolling friction, but the friction characteristics deteriorate (low wear resistance) with repeated sliding. From this result, it was found that carbon coating can provide good friction characteristics (rolling friction + wear resistance).

The lubricating filler according to the embodiment of the present invention can be suitably used, for example, to reduce friction in sliding parts in various machines that have parts that rub against each other and slide against each other (sliding parts).

10 Carbon material 20 Inorganic particle 30 Carbon material binding region 100 Organic-inorganic composite 200 Core-shell particle

Claims (4)

A lubricating filler in which the surface of a silica particle is coated with a carbon material,
The average particle diameter (D90) of the silica particles is 0.5 μm or more and 5.0 μm or less.
Lubricating filler. The lubricating filler according to claim 1, in which the average dynamic friction coefficient μ(20,1000) after 1000 reciprocating slides when the dispersion dispersed in a dispersion medium to a concentration of 20% by mass is subjected to a friction test is less than 0.04. The lubricating filler according to claim 2, in which the average dynamic friction coefficient μ(5,1000) after 1,000 reciprocating strokes when the dispersion is dispersed in a dispersion medium to a concentration of 5% by mass and subjected to a friction test is less than 0.04. A lubricating composition comprising the lubricating filler according to any one of claims 1 to 3.

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