Dispersion, lubricating composition, and method for producing dispersion

Abstract

Provided are: a dispersion with which nano-sized molybdenum disulfide particles capable of highly expressing lubricating performance can be stably dispersed even over time; a lubricating composition comprising the same; and a simple method for producing the same. Specifically, provided are: a dispersion comprising molybdenum disulfide particles (A) having a specific surface area of at least 40 m2 / g, and at least one compound (B) selected from the group consisting of secondary nitrogen-containing compounds and organic acid salts; and a lubricating composition obtained by mixing said dispersion with a base oil. The compound is preferably at least one compound (B1) selected from the group consisting of: compounds having a substituted succinimide group and a secondary nitrogen-containing group; alkylbenzene sulfonates; and alkyl salicylates.

Description

Dispersion, Lubricating Composition, and Method for Producing Dispersion

[0001] The present invention relates to a dispersion obtained by dispersing molybdenum disulfide particles, a method for producing the same, and a lubricating composition containing the same.

[0002] Molybdenum disulfide has long been known as a solid lubricant. In recent years, it has been clarified that nanosized molybdenum disulfide particles obtained by nanoparticle formation exhibit more excellent properties as solid lubricants (see, for example, Patent Documents 1 to 3). Further, a lubricant composition using a dispersant having a weight average molecular weight of 2000 daltons or more as a dispersant for metal nanoparticles which are concentric polyhedra having a multilayer structure or a laminated sheet-like structure has been provided (see, for example, Patent Document 4). Furthermore, in order to improve the dispersibility of molybdenum disulfide particles in a base oil, a lubricating composition obtained by performing surface treatment and further using a plurality of compounds in combination to uniformly disperse them has also been provided (see, for example, Patent Document 5).

[0003] Specification of Chinese Patent Application Publication No. 113897232 International Publication No. 2022 / 201610 International Publication No. 2023 / 182120 Special Table 2016-515663 Specification of Chinese Patent Application Publication No. 104911003

[0004] Although nanosized molybdenum disulfide particles are excellent in lubricating performance, they have a problem of dispersion stability because they are solid, and sedimentation and precipitation over time occur, so that it is often difficult to be used as a component of a DI package or engine oil. In recent years, from the viewpoint of improving fuel efficiency, the viscosity of engine oil has been decreasing, and the problem of dispersion stability has become more prominent when implementing nanosized molybdenum disulfide particles.

[0005] In Patent Document 1, molybdenum disulfide powder is crushed and a mixture containing dispersants such as 12-thiol, Span-80, polypropylene ethylene glycol, Tween-80, and oleic acid, along with a solvent, is uniformly dispersed under ultrasonic dispersion or high pressure to form nanosheets. This mixture is then washed with water and vacuum-dried to obtain sheet-like nano-sized particles. When mixing this with a base oil, it is again wetted with 12-thiol to form a lubricating composition. However, the process is complicated, and the dispersion stability after mixing with the base oil is not evaluated. Patent Document 2 introduces that dispersants further suppress the sedimentation of nano-sized molybdenum disulfide particles, and Patent Document 3 states that amines, ester compounds, phosphoric acid compounds, and amide compounds are suitable as dispersants, and also describes an example using oleylamine as a dispersant. However, the temporal stability of the dispersion was insufficient with these methods. Patent Document 4 only provides a general description of metal nanoparticles, and the examples use tungsten disulfide nanoparticles, and furthermore, the proportion of dispersant used is relatively high. In this document as well, the stability after dispersion is not evaluated. Patent document 5 describes preparing a lubricating composition after surface-treating nano-sized molybdenum disulfide particles to improve dispersibility. Furthermore, hydrothermal synthesis from molybdate or thiomolybdate salts generally makes it difficult to obtain molybdenum disulfide with high chemical purity, and the lubricating function may be inferior.

[0006] Therefore, the present invention aims to provide a dispersion of nano-sized molybdenum disulfide particles that can exhibit high lubrication performance and remain stably dispersed over time, a lubricating composition containing the same, and a simple method for producing the same.

[0007] As a result of diligent research, the inventors have discovered that in dispersions or lubricating compositions containing molybdenum disulfide particles, a combination of molybdenum disulfide particles having a specific specific surface area and a specific dispersant exhibits particularly good dispersion stability over time. Furthermore, they have found that by using this dispersant, media-less dispersion can be suitably applied, thereby improving productivity, leading to the completion of the present invention.

[0008] The present invention encompasses the following embodiments: [1] Specific surface area of ​​40 m² ２ A dispersion containing molybdenum disulfide particles (A) of 1g or more, and one or more compounds (B) selected from the group consisting of compounds having a secondary nitrogen and organic acid salts. [2] The dispersion according to [1], wherein compound (B) is one or more compounds (B1) selected from the group consisting of compounds having a substituted succinimide group and a group containing a secondary nitrogen, alkylbenzene sulfonates and alkyl salicylates. [3] The dispersion according to [1] or [2], wherein the molybdenum disulfide particles (A) have a 3R / 2H ratio of 0.25 or more, which is the ratio of the 3R crystal structure to the 2H crystal structure. [4] The dispersion according to any one of [1] to [3], wherein the dispersant (B) is a compound having a 3-polyalkenylpyrrole-2,5-dione-1-yl group. [5] The dispersant (B) is a compound of the following general formula (1)

[0009] A dispersion according to any one of [1] to [4], which is a compound represented by [Formula (1), where R represents a polyalkenyl group, n represents an integer of 1 or more, and R1 represents an n-valent organic group containing secondary nitrogen.] [6] A dispersion according to [5], wherein R in Formula (1) is a polyisobutenyl group. [7] A dispersion according to any one of [1] to [6], wherein the ratio of the molybdenum disulfide particles (A) to the compound (B) is in the range of 10 to 500 parts by mass per 100 parts by mass of the molybdenum disulfide particles (A). [8] A dispersion according to any one of [1] to [7], further containing petroleum resin (C). [9] A lubricating composition comprising the dispersion according to any one of [1] to [8] and a base oil.

[10] A specific surface area of ​​40 m² ２A method for producing a dispersion, comprising: a dispersion of molybdenum disulfide particles (A) of 1 / g or more; and one or more compounds (B) selected from the group consisting of compounds having a secondary nitrogen and organic acid salts, using a medialess dispersion method.

[11] The method for producing the dispersion according to

[10] , wherein compound (B) is one or more compounds (B1) selected from the group consisting of compounds having a substituted succinimide group and a group containing a secondary nitrogen, alkylbenzene sulfonates, and alkyl salicylates.

[12] A method for producing a dispersion according to

[10] , comprising mixing one or more compounds (B) selected from the group consisting of compounds having a secondary nitrogen and organic acid salts with a petroleum resin (C), and then further mixing the compounds with a specific surface area of ​​40 m². ２ A method for producing a dispersion, comprising adding molybdenum disulfide particles (A) of 1g or more and forming a dispersion using medialess dispersion.

[13] The method for producing a dispersion according to

[12] , wherein the compound (B) is one or more compounds (B1) selected from the group consisting of compounds having a substituted succinimide group and a group containing a secondary nitrogen, alkylbenzene sulfonates, and alkyl salicylates.

[0010] The present invention makes it possible to create a dispersion of specific molybdenum disulfide particles that exhibits excellent dispersion stability over time. Furthermore, by using a specific compound as a dispersant, dispersions and lubricating compositions can be provided by a simple method.

[0011] Figure 1 is a schematic diagram showing an example of an apparatus used to produce molybdenum trioxide particles, which are the raw material for molybdenum disulfide particles in this embodiment.

[0012] Next, embodiments for carrying out the present invention will be described in detail. The present invention is not limited to the following embodiments, and it should be understood that appropriate design changes, improvements, etc., can be made based on the ordinary knowledge of those skilled in the art, without departing from the spirit of the invention.

[0013] One embodiment of the dispersion has a specific surface area of ​​40 m². ２ It contains molybdenum disulfide particles (A) of 1g or more, and one or more compounds (B) selected from the group consisting of compounds having secondary nitrogen and organic acid salts.

[0014] <Molybdenum disulfide particles (A)> The dispersion of this embodiment contains molybdenum disulfide particles (A). Molybdenum compounds have been conventionally used as one of the solid lubricants. However, commercially available molybdenum disulfide is in the form of powder by so-called grinding, so its particle size is large and its specific surface area is small. Furthermore, since the specific gravity is as large as about 5, even when trying to disperse it in a liquid medium, sedimentation easily occurs, and once it sediments, it adheres and it is difficult to redisperse.

[0015] Also, even if trying to use molybdenum disulfide particles with a small specific surface area as a lubricant as they are, in recent years, as a result of the demand for those with high lubrication performance due to technological innovation, it is difficult to exhibit a sufficient effect, the interaction with the dispersant is insufficient, and it is difficult to obtain sufficient dispersibility.

[0016] Therefore, in the present invention, it is essential to use molybdenum disulfide particles (A) having a specific surface area of 40 m ２ / g or more. Furthermore, it is more preferably 50 to 300 m ２ / g, even more preferably 70 to 250 m ２ / g, and particularly preferably 90 to 200 m ２ / g. The specific surface area is measured from the adsorption amount of nitrogen gas by the BET method.

[0017] When the specific surface area of the molybdenum disulfide particles (A) measured by the BET method is 40 m ２ / g or more, when the primary particles thereof exist between the friction surfaces of the sliding part, the contact area with the friction surface can be increased, and the area where the friction surfaces of the sliding part contact each other can be further reduced, so excellent anti-friction and anti-wear characteristics can be exhibited. Also, by using a specific compound described later as a dispersant for molybdenum disulfide particles (A) having a specific surface area of 40 m ２ / g or more, due to the large specific surface area, the dispersion effect is enhanced, and it is considered that the stability as a dispersion, particularly the stability over time, can be exhibited.

[0018] Also, the median diameter D obtained by a dynamic light scattering type particle size distribution measuring device for the molybdenum disulfide particles (A) ５０Preferably, the wavelength is 400 nm or less, more preferably 200 nm or less, particularly preferably 150 nm or less, and most preferably 100 nm or less. ５０ The lower limit is not particularly limited; for example, it may be 5 nm or more, or 10 nm or more.

[0019] Furthermore, the molybdenum disulfide particles (A) are not perfectly spherical, but rather have a particle thickness determined by observation with an atomic force microscope (AFM) and the aforementioned median diameter D. ５０ The [aspect ratio] obtained from this = [median diameter D] ５０ It is preferable that the ratio of ]÷[particle thickness] is in the range of 2 to 110. In particular, it is preferable that the aspect ratio is 5 or more, more preferably 10 or more, and most preferably 15 or more.

[0020] The molybdenum disulfide particles (A) preferably contain both a 2H crystal structure and a 3R crystal structure of molybdenum disulfide, and it is particularly preferable that the ratio of the 3R crystal structure to the 2H crystal structure, 3R / 2H, is 0.25 or greater. In molybdenum disulfide having a layered crystal structure, the interaction between each layer of the 3R structure is smaller than that of the 2H structure, making it easier to break down, less likely to cause aggregation of primary particles, and easier to achieve stable dispersion. It is particularly preferable that the ratio be 1 or greater, and even more preferable that it be 1.5 or greater. The ratio 3R / 2H can be determined by using high-resolution powder X-ray diffraction (XRD) with a high-power source or Rietveld analysis with powder XRD.

[0021] The fact that the molybdenum disulfide particles (A) contain a metastable 3R crystal structure can also be distinguished by the fact that in the spectrum obtained from powder X-ray diffraction (XRD) using Cu-Kα rays as the X-ray source, the peaks around 39.5° and the peaks around 49.5° both consist of composite peaks of the 2H crystal structure and the 3R crystal structure.

[0022] Furthermore, it is preferable that the molybdenum disulfide particles (A) have a spectrum obtained from powder X-ray diffraction (XRD) using Cu-Kα rays as an X-ray source, in which the peak around 39.5° and the peak around 49.5° both consist of composite peaks of the 2H crystal structure and the 3R crystal structure, and the full width at half maximum is 1° or more. In addition, the molybdenum disulfide particles (A) may also contain crystal structures other than the 2H crystal structure and the 3R crystal structure of molybdenum disulfide, such as the 1H crystal structure.

[0023] Furthermore, the molybdenum disulfide particles (A) may also contain an amorphous phase. The relative abundance of the amorphous phase of the molybdenum disulfide particles is expressed as 100 (%) - (degree of crystallinity (%)), and is preferably 5% or more, more preferably 15% or more, and even more preferably 20% or more. When the relative abundance of the amorphous phase of the molybdenum disulfide particles is 5% or more, the coefficient of friction is further reduced, and the frictional properties can be improved.

[0024] As described above, the primary particle shape of the molybdenum disulfide particles (A) in the two-dimensional image captured by a transmission electron microscope (TEM) has an aspect ratio in the range of 2 to 110, and may be plate-shaped, needle-shaped, string-shaped, ribbon-shaped, or sheet-shaped, and may include a combination of these shapes. The shape of the molybdenum disulfide particles (A) is preferably ribbon-shaped or sheet-shaped, and the shape of 50 primary particles of molybdenum disulfide particles (A) preferably has an average size in the range of length (vertical) × width (horizontal) = 2 to 600 nm × 1 to 500 nm, more preferably in the range of 2 to 500 nm × 1 to 400 nm, and particularly preferably in the range of 2 to 400 nm × 1 to 300 nm. Being ribbon-shaped or sheet-shaped allows for a large specific surface area of ​​the molybdenum disulfide particles (A). Here, being ribbon-shaped or sheet-shaped means being in a thin layer shape.

[0025] The primary particle shape of the molybdenum disulfide particles (A) is not a simple sphere, but rather a ribbon-like or sheet-like shape with a large aspect ratio. This is expected to more efficiently cover the friction surfaces of the materials that are about to come into contact, thereby reducing the probability of contact between the friction surfaces of the materials (or contact area × time), and making seizing due to friction less likely.

[0026] The primary particles of the molybdenum disulfide particles (A) are composed of layers that approach each other through relatively weak interactions, and can be easily displaced by external forces such as friction. Therefore, when the primary particles of the molybdenum disulfide particles (A) are sandwiched between two metals that are being slidable, the frictional force causes the layers that make up the primary particles to slide against each other, reducing the apparent coefficient of friction and preventing contact between the metals that are being slidable.

[0027] In the radial distribution function obtained from the broad-field X-ray absorption fine structure (EXAFS) spectrum of the molybdenum K absorption edge of the molybdenum molybdenum particles (A), the ratio (I / II) of the peak intensity I due to Mo-S to the peak intensity II due to Mo-Mo is preferably greater than 1.0, more preferably 1.1 or greater, and particularly preferably 1.2 or greater.

[0028] Whether the crystal structure of molybdenum disulfide is a 2H crystal structure or a 3R crystal structure, the distance between Mo and S atoms is almost the same due to covalent bonding. Therefore, in the broad-field X-ray absorption fine structure (EXAFS) spectrum of molybdenum at the K absorption edge, the intensity of the peak caused by Mo-S is the same. On the other hand, because the 2H crystal structure of molybdenum disulfide is hexagonal, another hexagon is located directly below the hexagon of a Mo atom at a 90° angle. As a result, the distance between Mo and Mo atoms becomes shorter, and the peak intensity II caused by Mo-Mo becomes stronger.

[0029] Conversely, because the 3R crystal structure of molybdenum disulfide is rhombohedral, the hexagons are not directly below the 90° hexagons, but are offset by half a hexagon. As a result, the distance between Mo-Mo atoms increases, and the peak intensity II caused by Mo-Mo atoms weakens. In the pure 2H crystal structure of molybdenum disulfide, the ratio (I / II) is small, but as the 3R crystal structure is included, the ratio (I / II) increases. In the 3R crystal structure, the hexagons of the Mo atoms in each of the three layers are offset from each other by half a hexagon. Therefore, compared to the 2H crystal structure where the hexagons of the Mo atoms in the two layers are arranged vertically and regularly, the interaction between each layer is smaller, and it is expected that the layer will be more slippery.

[0030] <Method for producing molybdenum disulfide particles (A)> The molybdenum disulfide particles (A) can be produced, for example, by heating molybdenum trioxide particles having an average primary particle size of 5 to 1000 nm at a temperature of 300 to 800°C in the presence of a sulfur source.

[0031] The average particle size of primary molybdenum trioxide particles is defined as the average of the primary particle sizes of 50 randomly selected primary particles. This is achieved by photographing molybdenum trioxide particles with a scanning electron microscope (SEM) or transmission electron microscope (TEM), measuring the major axis (the longest observed Ferret diameter) and minor axis (the shortest Ferret diameter perpendicular to the longest Ferret diameter) of the smallest unit particles constituting the aggregate on the two-dimensional image (i.e., primary particles), and taking the average of these values ​​as the primary particle size.

[0032] The molybdenum oxide particles used in the production of the molybdenum disulfide particles (A) preferably consist of an aggregate of primary particles containing a β-crystalline structure of molybdenum trioxide. Compared to conventional molybdenum trioxide particles consisting only of α-crystals as their crystalline structure, these molybdenum oxide particles have better reactivity with sulfur and contain a β-crystalline structure of molybdenum trioxide, so in the reaction with the sulfur source, MoS ２ Conversion rate R Ｃ It can be made larger.

[0033] The β-crystal structure of molybdenum trioxide is shown in the spectrum obtained from powder X-ray diffraction (XRD) using Cu-Kα rays as the X-ray source, as MoO３ This can be confirmed by the presence of a peak (around 2θ: 23.01°, No. 86426 (Inorganic Crystal Structure Database (ICSD))) which is attributed to the (011) plane of the β crystal. The α crystal structure of molybdenum trioxide is MoO ３ This can be confirmed by the presence of a peak on the (021) plane of the α crystal (around 2θ: 27.32°, No. 166363 (Inorganic Crystal Structure Database (ICSD))).

[0034] Examples of sulfur sources include sulfur and hydrogen sulfide, which may be used individually or in combination.

[0035] The method for producing the molybdenum disulfide particles (A) may include heating molybdenum trioxide particles, which consist of an aggregate of primary particles containing a β-crystalline structure of molybdenum trioxide, at a temperature of 200 to 800°C in the absence of a sulfur source, and then heating them at a temperature of 200 to 1000°C in the presence of a sulfur source.

[0036] The heating time in the presence of a sulfur source may be any amount of time required for the sulfidation reaction to proceed sufficiently, and may be 1 to 20 hours, 2 to 15 hours, or 3 to 10 hours.

[0037] In the method for producing the molybdenum disulfide particles (A), the MoO ３ The ratio of the amount of sulfur in the sulfur source to the total amount of other materials is preferably such that the sulfidation reaction proceeds sufficiently. ３ The amount of sulfur in the sulfur source is preferably 250 mol% or more, preferably 400 mol% or more, and preferably 500 mol% or more, per 100 mol% of the total amount. ３ The amount of sulfur in the sulfur source may be 3000 mol% or less, 2000 mol% or less, or 1500 mol% or less per 100 mol% of the total amount.

[0038] In the method for producing the molybdenum disulfide particles (A), the heating temperature in the presence of the sulfur source may be any temperature at which the sulfurization reaction proceeds sufficiently, preferably 320°C or higher, more preferably 340°C or higher, and particularly preferably 360°C or higher. It may also be 320 to 1000°C, 340 to 1000°C, or 360 to 600°C.

[0039] In the method for producing the molybdenum disulfide particles (A), it is preferable that the average particle size of the primary particles of the molybdenum trioxide particles is 1 μm or less. From the viewpoint of reactivity with sulfur, it is more preferable that it is 600 nm or less, even more preferable that it is 400 nm or less, and particularly preferable that it is 200 nm or less. The average particle size of the primary particles of the molybdenum trioxide particles may be 10 nm or more, 20 nm or more, or 40 nm or more.

[0040] In the method for producing the molybdenum disulfide particles (A), the molybdenum trioxide particles are measured by X-ray fluorescence (XRF) ３ It is preferable that the content ratio of is 99.6% or more, thereby MoS ２ Conversion rate R Ｃ This allows for a larger size, enabling the production of high-purity molybdenum sulfide with good storage stability, free from the risk of generating sulfides derived from impurities.

[0041] In the method for producing the molybdenum disulfide particles (A), the molybdenum trioxide particles are such that, in the spectrum obtained from powder X-ray diffraction (XRD) using Cu-Kα rays as the X-ray source, MoO ３ The peak intensity attributable to the (011) plane of the β crystal of MoO ３ It is preferable that the ratio (β(011) / α(021)) to the peak intensity attributed to the (021) plane of the α crystal is 0.1 or greater.

[0042] MoO ３ The peak intensity attributable to the (011) plane of the β crystal, and MoO ３ For the peak intensities attributed to the (021) plane of the α crystal, the maximum peak intensity is read, and the ratio (β(011) / α(021)) is determined.

[0043] In the molybdenum trioxide particles, the ratio (β(011) / α(021)) is preferably 0.1 to 10.0, more preferably 0.2 to 10.0, and particularly preferably 0.4 to 10.0.

[0044] The molybdenum trioxide particles have a specific surface area of ​​10 m² as measured by the BET method. ２ / g to 150m ２ It is preferable that the amount is / g.

[0045] In the molybdenum trioxide particles, the specific surface area is set to 10 m in order to achieve good reactivity with sulfur. ２ It is preferable that it be 20 m or more ２ It is preferable that it be 30m or more per gram. ２ It is preferable that the amount is 120 m or more. In the molybdenum trioxide particles, since it is easier to manufacture, ２ It is preferable that it be less than or equal to 100m ２ It may be less than / g, and 80m ２ It may be less than / g.

[0046] In the aforementioned molybdenum trioxide particles, it is preferable that the ratio (I / II) of the peak intensity I due to Mo-O to the peak intensity II due to Mo-Mo in the radial distribution function obtained from the broad-field X-ray absorption fine structure (EXAFS) spectrum of the K absorption edge of molybdenum is greater than 1.1.

[0047] The peak intensity I, caused by Mo-O, and the peak intensity II, caused by Mo-Mo, are determined by reading the maximum peak intensity and calculating the ratio (I / II). The ratio (I / II) is calculated for molybdenum trioxide particles, where MoO ３ This is considered an indicator of whether a β-crystal structure has been obtained, and the larger the ratio (I / II), the better the reactivity with sulfur.

[0048] In the molybdenum trioxide particles, the ratio (I / II) is preferably 1.1 to 5.0, may be 1.2 to 4.0, or 1.2 to 3.0.

[0049] (Method for producing molybdenum trioxide particles) The molybdenum trioxide particles can be produced by mechanically crushing commercially available molybdenum trioxide to the desired size and using it as is. Alternatively, they can be produced by vaporizing a molybdenum oxide precursor compound to form molybdenum trioxide vapor, and then cooling the molybdenum trioxide vapor.

[0050] The method for producing the molybdenum trioxide particles includes calcining a raw material mixture containing a molybdenum oxide precursor compound and a metal compound other than the molybdenum oxide precursor compound, vaporizing the molybdenum oxide precursor compound to form molybdenum trioxide vapor, and preferably the proportion of the metal compound to 100% by mass of the raw material mixture is 70% by mass or less in terms of oxide.

[0051] The method for producing the molybdenum trioxide particles can be suitably carried out using the manufacturing apparatus 1 shown in Figure 1.

[0052] Figure 1 is a schematic diagram of an example of an apparatus used for manufacturing molybdenum trioxide particles. The manufacturing apparatus 1 includes a calcination furnace 2 that calcines a molybdenum oxide precursor compound or the raw material mixture to vaporize the molybdenum oxide precursor compound, a cross-shaped cooling pipe 3 connected to the calcination furnace 2 to atomize the molybdenum trioxide vapor vaporized by the calcination, and a recovery machine 4 which is a recovery means for recovering the molybdenum trioxide particles atomized in the cooling pipe 3. In this case, the calcination furnace 2 and the cooling pipe 3 are connected via an exhaust port 5. The cooling pipe 3 has an opening adjustment damper 6 at the left end of an outside air intake port (not shown) and an observation window 7 at the upper end. The recovery machine 4 is connected to an exhaust device 8, which is a first blowing means. When the exhaust device 8 exhausts air, the recovery machine 4 and the cooling pipe 3 are drawn in, and outside air is blown into the cooling pipe 3 from the opening adjustment damper 6 of the cooling pipe 3. In other words, the exhaust device 8 performs a suction function, passively generating airflow into the cooling pipe 3. The manufacturing apparatus 1 may also have an external cooling device 9, which makes it possible to arbitrarily control the cooling conditions of the molybdenum trioxide vapor generated from the firing furnace 2.

[0053] The opening adjustment damper 6 draws in air from the outside air intake, cools the molybdenum trioxide vapor vaporized in the firing furnace 2 under an air atmosphere, and converts it into molybdenum trioxide particles, thereby making the ratio (I / II) greater than 1.1, and in the molybdenum trioxide particles, MoO ３ The β crystal structure is easily obtained. Cooling molybdenum trioxide vapor in a nitrogen atmosphere with a low oxygen concentration, such as when molybdenum trioxide vapor is cooled using liquid nitrogen, tends to increase the oxygen vacancy density and decrease the ratio (I / II).

[0054] As the molybdenum oxide precursor compound, a precursor compound for forming molybdenum trioxide particles consisting of an aggregate of primary particles containing the β-crystal structure of molybdenum trioxide is preferred.

[0055] The molybdenum oxide precursor compound is not particularly limited as long as it forms molybdenum trioxide vapor upon calcination, but examples include metallic molybdenum, molybdenum trioxide, molybdenum dioxide, and molybdenum sulfide. It is preferable to use commercially available α-crystalline molybdenum trioxide as the molybdenum oxide precursor compound. Furthermore, when ammonium molybdate is used as the molybdenum oxide precursor compound, it is converted to thermodynamically stable molybdenum trioxide upon calcination, so the vaporized molybdenum oxide precursor compound is the aforementioned molybdenum trioxide.

[0056] Molybdenum trioxide vapor can also be formed by calcining a raw material mixture containing a molybdenum oxide precursor compound and a metal compound other than the said molybdenum oxide precursor compound.

[0057] Other metal compounds besides the molybdenum oxide precursor compound are not particularly limited, but include aluminum compounds, silicon compounds, titanium compounds, magnesium compounds, sodium compounds, potassium compounds, zirconium compounds, yttrium compounds, zinc compounds, copper compounds, iron compounds, and the like. Of these, aluminum compounds, silicon compounds, titanium compounds, and magnesium compounds are preferred.

[0058] In some cases, an intermediate may be formed between the molybdenum oxide precursor compound and a metal compound other than the molybdenum oxide precursor compound. However, even in this case, the intermediate can be decomposed by calcination, allowing molybdenum trioxide to be vaporized in a thermodynamically stable form.

[0059] As for metal compounds other than the molybdenum oxide precursor compound, it is preferable to use an aluminum compound to prevent damage to the firing furnace, and it is also acceptable not to use any metal compounds other than the molybdenum oxide precursor compound in order to improve the purity of the molybdenum trioxide particles.

[0060] Examples of aluminum compounds include aluminum chloride, aluminum sulfate, basic aluminum acetate, aluminum hydroxide, boehmite, pseudoboehmite, transition aluminum oxides (such as γ-aluminum oxide, δ-aluminum oxide, and θ-aluminum oxide), α-aluminum oxide, and mixed aluminum oxides having two or more crystalline phases.

[0061] When calcining a raw material mixture containing a molybdenum oxide precursor compound and a metal compound other than the molybdenum oxide precursor compound, the content ratio of the molybdenum oxide precursor compound to 100% by mass of the raw material mixture is preferably 40% to 100%, may be 45% to 100%, or 50% to 100%.

[0062] The firing temperature varies depending on the molybdenum oxide precursor compound, metal compound, and desired molybdenum trioxide particles used, but it is generally preferable to set the temperature at which the intermediate can decompose. For example, when a molybdenum compound is used as the molybdenum oxide precursor compound and an aluminum compound is used as the metal compound, aluminum molybdate may be formed as an intermediate, so the firing temperature is preferably 500°C to 1500°C, more preferably 600°C to 1550°C, and even more preferably 700°C to 1600°C.

[0063] There are no particular restrictions on the firing time; for example, it can be between 1 minute and 30 hours, between 10 minutes and 25 hours, or between 100 minutes and 20 hours.

[0064] The heating rate varies depending on the molybdenum oxide precursor compound used, the metal compound, and the properties of the desired molybdenum trioxide particles, but from the viewpoint of manufacturing efficiency, it is preferably 0.1 to 100°C / min, more preferably 1 to 50°C / min, and even more preferably 2 to 10°C / min.

[0065] The internal pressure inside the firing furnace is not particularly limited and may be positive or reduced pressure. However, from the viewpoint of suitably discharging the molybdenum oxide precursor compound from the firing furnace to the cooling pipe, firing is preferably carried out under reduced pressure. Specifically, the degree of reduced pressure is preferably -5000 to -10 Pa, more preferably -2000 to -20 Pa, and even more preferably -1000 to -50 Pa. A reduced pressure of -5000 Pa or higher is preferable because it does not require excessive airtightness or mechanical strength of the firing furnace, thereby reducing manufacturing costs. On the other hand, a reduced pressure of -10 Pa or lower is preferable because it prevents clogging of the molybdenum oxide precursor compound at the firing furnace outlet.

[0066] Furthermore, when gas is blown into the firing furnace during firing, the temperature of the blown gas is preferably 5 to 500°C, and more preferably 10 to 100°C.

[0067] Furthermore, the gas blowing speed is preferably 1 to 500 L / min, and more preferably 10 to 200 L / min, per 100 L of the effective volume of the firing furnace.

[0068] The temperature of the vaporized molybdenum trioxide vapor varies depending on the type of molybdenum oxide precursor compound used, but is preferably 200 to 2000°C, and more preferably 400 to 1500°C. When the temperature of the vaporized molybdenum trioxide vapor is 2000°C or lower, it tends to be easily atomized in the cooling pipe by blowing in outside air (0 to 100°C).

[0069] The discharge rate of molybdenum trioxide vapor discharged from the firing furnace can be controlled by the amount of the molybdenum oxide precursor compound used, the amount of the metal compound used, the temperature of the firing furnace, the amount of gas supplied into the firing furnace, and the diameter of the firing furnace exhaust port. Although it also varies depending on the cooling capacity of the cooling pipe, the discharge rate of molybdenum trioxide vapor from the firing furnace to the cooling pipe is preferably 0.001 to 100 g / min, and more preferably 0.1 to 50 g / min.

[0070] Furthermore, the molybdenum trioxide vapor content in the gas discharged from the calcination furnace is preferably 0.01 to 1000 mg / L, and more preferably 1 to 500 mg / L.

[0071] Next, the molybdenum trioxide vapor is cooled to atomize it. Cooling of the molybdenum trioxide vapor is achieved by lowering the temperature of the cooling pipe. In this case, cooling methods include cooling by blowing gas into the cooling pipe, cooling by the cooling mechanism of the cooling pipe, and cooling by an external cooling device, as described above.

[0072] Cooling of molybdenum trioxide vapor is preferably carried out in an air atmosphere. By cooling molybdenum trioxide vapor in an air atmosphere and converting it into molybdenum trioxide particles, the ratio (I / II) can be made greater than 1.1, and in the molybdenum trioxide particles, MoO ３ The β crystal structure is easily obtained.

[0073] The cooling temperature (cooling pipe temperature) is not particularly limited, but is preferably -100 to 600°C, and more preferably -50 to 400°C.

[0074] The cooling rate of molybdenum trioxide vapor is not particularly limited, but is preferably 100 to 100,000°C / s, and more preferably 1,000 to 50,000°C / s. It should be noted that the faster the cooling rate of molybdenum trioxide vapor, the more likely it is to yield molybdenum trioxide particles with smaller particle sizes and larger specific surface areas.

[0075] When the cooling means is cooling by blowing gas into a cooling pipe, the temperature of the blown gas is preferably -100 to 300°C, and more preferably -50 to 100°C.

[0076] Furthermore, the gas blowing speed is 0.1 to 20 m / s. ３ It is preferably / min, and 1 to 10m ３ It is more preferable that the gas blowing velocity is 0.1 m / min. ３ A value of 20 m / min or higher is preferable because it allows for a high cooling rate and prevents clogging of the cooling pipes. On the other hand, a gas blowing speed of 20 m / min is preferable. ３ A value of / min or less is preferable because it eliminates the need for an expensive first blowing means (such as an exhaust fan), thereby lowering manufacturing costs.

[0077] The particles obtained by cooling molybdenum trioxide vapor are transported to a recovery machine and collected.

[0078] The method for producing the molybdenum trioxide particles may also involve cooling the molybdenum trioxide vapor to obtain the particles, and then firing them again at a temperature of 100°C to 320°C.

[0079] In other words, the molybdenum trioxide particles obtained by the above method for producing molybdenum trioxide particles may be calcined again at a temperature of 100°C to 320°C. The calcination temperature for the second calcination may be 120°C to 280°C or 140°C to 240°C. The calcination time for the second calcination may be, for example, 1 minute to 4 hours, 10 minutes to 5 hours, or 100 minutes to 6 hours. However, by calcining again, a part of the β crystal structure of molybdenum trioxide will disappear, and if calcined at a temperature of 350°C or higher for 4 hours, the β crystal structure in the molybdenum trioxide particles will disappear, the ratio (β(011) / α(021)) will become 0, and the reactivity with sulfur will be impaired. By the method for producing molybdenum trioxide particles described above, molybdenum trioxide particles suitable for producing the above molybdenum disulfide particles (A) can be produced.

[0080] <Compound (B)> The dispersion in this embodiment uses one or more compounds (B) selected from the group consisting of compounds having secondary nitrogen and organic acid salts. After repeated studies on compounds that can stably disperse the aforementioned specific molybdenum disulfide particles (A) and maintain their dispersibility even after long-term storage, it was found that carboxymethylcellulose and oleylamine, which have been conventionally used for dispersing solid lubricants, lack sufficient dispersion stability, and it was found that the use of the aforementioned specific compound is essential. By using this compound (B) as a dispersant, it becomes possible to easily disperse it in the base oil without using any special process when using it as a lubricating composition as described later. Furthermore, even if the molybdenum disulfide particles (A) come into contact with each other during long-term storage, strong adhesion does not occur, and it is possible to redisperse them.

[0081] Examples of compounds having a secondary nitrogen as compound (B) include polyalkylene polyamines, polyoxyalkylene polyamines alone, or various compounds having polyalkylene polyamino groups or polyoxyalkylene polyamino groups as substituents, N-methylaniline which may have substituents on the ring, and piperidine which may have substituents on the ring. Among these, it is preferable to use a compound having a substituted succinimide group and a group containing a secondary nitrogen.

[0082] The compound having the substituted succinimide group and the secondary nitrogen-containing group is not particularly limited, and commercially available compounds can be used as is. The structural formula and properties of commercially available polyamine-polyisobutenylsuccinimide (PIBSI) are described on page 31 of the Journal of the Chemical Society of Japan, 1990 (1), and these commercially available products can be used as is. Alternatively, it may be synthesized by known methods as shown in succinimide-A to C described on pages 112-113 of the Journal of the Japan Petroleum Society, 1970 (13).

[0083] As the substituted succinimide group, for example, a 3-polyalkenylpyrrole-2,5dione-1-yl group is preferred, and a 3-polyisobutenylpyrrole-2,5dione-1-yl group is more preferred.

[0084] Examples of compounds having the substituted succinimide group and a group containing a secondary nitrogen include the following general formula (1):

[0085] [In formula (1), R represents a polyalkenyl group, and n represents an integer of 1 or more, R １ represents an n-valent organic group containing secondary nitrogen. It is preferable that the compound is represented by ].

[0086] In formula (1), R is more preferably a polybutenyl group or a polyisobutenyl group. The weight-average molecular weight of the polyalkenyl group is preferably 300 to 4000, more preferably 500 to 3000, and even more preferably 600 to 2000.

[0087] R in formula (1) １ n is an n-valent organic group containing secondary nitrogen, where n is an integer of 1 or more, particularly preferably an integer between 1 and 5, and most preferably an integer between 1 and 3.

[0088] R in formula (1) １ Preferably, the organic group is represented by the following general formulas (2) to (5), and particularly preferably by the organic group represented by (2) to (4).

[0089]

[0090] [In formula (2), m is an integer between 2 and 5, and in formula (3), q is an integer between 1 and 4. In both cases, the terminal carbon atom is the bonding site with the nitrogen atom in formula (1).]

[0091] Examples of organic salts for compound (B) include monoalkyl sulfates, alkylpolyoxyethylene sulfates, alkylbenzene sulfonates, monoalkyl phosphates, polycarboxylates, alkyl sulfonates, alkane sulfonates, α-olefin sulfonates, and alkyl salicylates, with alkylbenzene sulfonates and alkyl salicylates being particularly preferred.

[0092] The alkylbenzene sulfonate is preferably a calcium salt or a magnesium salt, and more preferably a calcium salt. The alkyl group of the alkylbenzene sulfonate is preferably an alkyl group having 12 to 24 carbon atoms, and there may be two or more alkyl groups, and it may also have a hydroxyl group as a substituent on the benzene ring. The alkylbenzene sulfonate may be overbasicized with an excess of base, and such a base is preferably calcium carbonate.

[0093] The alkyl salicylate is preferably a calcium salt or a magnesium salt, and more preferably a calcium salt. The alkyl group of the alkyl salicylate is preferably an alkyl group having 12 to 24 carbon atoms.

[0094] In other words, it is preferable that the compound (B) is one or more compounds (B1) selected from the group consisting of compounds having a substituted succinimide group and a group containing a secondary nitrogen, alkylbenzene sulfonates, and alkyl salicylates. Such a dispersant (B) may consist of a single compound, or two or more may be used in combination.

[0095] The proportion of the dispersant (B) used is not particularly limited, as long as it can adequately disperse the molybdenum disulfide particles (A). However, a proportion of 10 to 500 parts by mass per 100 parts by mass of the molybdenum disulfide particles (A) is preferable from the viewpoint of easily balancing dispersibility and lubrication performance, a proportion of 20 to 300 parts by mass is more preferable, and a proportion of 50 to 200 parts by mass is most preferable.

[0096] Furthermore, the dispersion, which is one embodiment of the present invention, may be in a liquid state or a paste state (semi-solid) at room temperature (25°C). From the viewpoint of preventing sedimentation during long-term storage, a paste state is preferable.

[0097] Furthermore, other dispersants may be used in combination as needed, to the extent that they do not inhibit the effects of the present invention. Commercially available dispersants can be used as is, for example, octylamine, decylamine, tetradecylamine, hexadecylamine, eicosylamine, dodecenylamine, hexadecenylamine, octadecenylamine, octadecadienylamine, stearylamine, palmitylamine, oleylamine, linoleylamine, linolenylamine, 9,12-octadecadienylamine (linoleamine), laurylamine, 9,12,15-octadecadrienyamine, monooleyltrimethylammonium chloride, dioleyldimethylammonium chloride, polyalkyleneoxymonomethyldioleylammonium chloride, bis(polyalkyleneoxy)monomethylmonoleylammonium chloride, oleylglycerin ester, stearylglycerin Examples include ester compounds such as esters and laurylglycerin esters, amide compounds such as laurylamide, oleylamide, and stearylamide, higher alcohol compounds such as decyl alcohol, lauryl alcohol, cetyl alcohol, stearyl alcohol, and lauryl myristyl alcohol, and thiol compounds such as decanethiol, dodecanethiol, hexadecanethiol, nonanthiol, octadecanethiol, octanthiol, pentadecanethiol, tetradecanethiol, decanethiol, undecanethiol, dodecanethiol, mercaptoundecyltrifluoroacetate, 1H,1H,2H,2H-perfluorodecanethiol, 2-ethylhexanethiol, cis-9-octadecene-1-thiol, tert-dodecylmercaptan, and tert-nonylmercaptan.

[0098] Furthermore, compounds obtained by reacting relatively low molecular weight amine compounds with long-chain fatty acids can also be used. Examples of amine compounds that can be used in this case include diamine compounds such as pentamethylenediamine, hexamethylenediamine, m-xylylenediamine, p-xylylenediamine, isophoronediamine, bis(aminomethyl)cyclohexane, bis(aminocyclohexyl)methane, 2,5-bis(aminomethyl)bicyclo-[2.2.1]-heptane, 2,6-bis(aminomethyl)bicyclo-[2.2.1]-heptane, tolylenediamine, 4,4'-diphenylmethanediamine, and phenylenediamine. Alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine may also be used. This amine compound contains linear fatty acids such as caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nonadecanoic acid, and arachidic acid, as well as 2-butyl-5-methylpentanoic acid, 2-isobutyl-5-methylpentanoic acid, dimethyloctanoic acid, dimethylnonanoic acid, 2-butyl-5-methylhexanoic acid, methylundecanoic acid, dimethyldecanoic acid, 2-ethyl-3-methylnonanoic acid, 2,2-dimethyl-4-ethyloctanoic acid, methyldocosanoic acid, 2-propyl-3-methylnonanoic acid, methyltridecanoic acid, dimethyldodecanoic acid, 2-butyl-3-methylnonanoic acid, methyltetradecanoic acid, ethyltridecanoic acid, and propyldodecanoic acid. Acids, butyl undecanoic acid, pentyldecanoic acid, hexylnonanoic acid, 2-(3-methylbutyl)-3-methylnonanoic acid, 2-(2-methylbutyl)-3-methylnonanoic acid, butylethylnonanoic acid, methylpentadecanoic acid, ethyltetradecanoic acid, propyltridecanoic acid, butyldodecanoic acid, pentyl undecanoic acid, hexyldecanoic acid, heptylnonanoic acid, dimethyltetradecanoic acid, butylpentylheptanoic acid, trimethyltridecanoic acid, methylhexadecanoic acid, ethylpentadecanoic acid, propyltetradecanoic acid, butyltridecanoic acid, pentyldodecanoic acid, hexyl undecanoic acid, heptyldecanoic acid, methylheptylnonanoic acid, dipentylheptanoic acid, methylheptadecanoic acid, ethylhexadecanoic acid, ethylhexadecanoic acid,Branched fatty acids such as propylpentadecanoic acid, butyltetradecanoic acid, pentyltridecanoic acid, hexyldodecanoic acid, heptylundecanoic acid, octyldecanoic acid, dimethylhexadecanoic acid, methyloctylnonanoic acid, methyloctadecanoic acid, ethylheptadecanoic acid, dimethylheptadecanoic acid, methyloctyldecanoic acid, methylnonadecanoic acid, methylnonadecanoic acid, dimethyloctadecanoic acid, and butylheptylnonanoic acid, octenic acid, nonene Straight-chain monoenoic acids such as decenoic acid, caproleic acid, undecylenic acid, lindelic acid, sucroseic acid, lauroleic acid, tridecenoic acid, tuzic acid, myristoleic acid, pentadecenoic acid, hexedecenoic acid, palmitoleic acid, heptadecenoic acid, octadecenoic acid, oleic acid, nonadecenoic acid, gondoiic acid; methylheptenoic acid, methylnonenic acid, methylundecenoic acid, dimethyldecenoic acid, methyldodecenoic acid, methyltridecenoic acid, dimethyldodecenoic acid Branched monoenoic acids such as chlorophosate, dimethyltridecenoic acid, methyloctadecenoic acid, dimethylheptadecenoic acid, and ethyloctadecenoic acid; di or trienoic acids such as linoleic acid, linoleidic acid, eleostearic acid, linolenic acid, linoleneelaidic acid, pseudoeleostearic acid, parinalic acid, and arachidonic acid; octinic acid, nonicinic acid, decinic acid, undecinic acid, dodecinic acid, tridecinic acid, tetradecinic acid, pentadecinic acid, hep Dispersants can be obtained by reacting fatty acids such as acetylene acids (e.g., tadecic acid, octadecic acid, nonadecinic acid, dimethyloctadecic acid) and cyclic acids (e.g., methyleneoctadecenoic acid, methyleneoctadecanoic acid, aleprolic acid, aleprestic acid, aleprilic acid, aleprilic acid, hydrinocarpunic acid, schormuglic acid, golic acid, α-cyclopentylic acid, α-cyclohexylic acid, α-cyclopentylethylic acid). The reaction between amine compounds and fatty acids is not particularly limited, and well-known methods can be used as appropriate.

[0099] Furthermore, compounds obtained by reacting relatively low molecular weight isocyanate compounds with long-chain fatty acids as described above can also be used. Examples of isocyanate compounds that can be used in this case include aliphatic diisocyanate compounds such as butane diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate; alicyclic diisocyanate compounds such as norbornane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, and hydrogenated diphenylmethane diisocyanate; aromatic diisocyanate compounds such as tolylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diisocyanato-3,3'-dimethylbiphenyl, and o-tolidine diisocyanate, as well as isocyanate compounds such as isocyanurate modified versions, biuret modified versions, and allophanate modified versions thereof. A dispersant can be obtained by reacting this isocyanate compound with the aforementioned fatty acid. The reaction between the isocyanate compound and the fatty acid is not particularly limited, and any well-known method can be used as appropriate.

[0100] Furthermore, the compounds obtained by reacting the epoxy groups in the epoxy compounds with the aforementioned fatty acids contain hydroxyl groups, ether bonds, and ester bonds resulting from the ring-opening reaction of the epoxy groups, which improves their dispersion properties and makes them desirable dispersants.

[0101] The epoxy compound can be a compound with a relatively low molecular weight used alone, or as an epoxy resin containing compounds with different repeating numbers, or a mixture of compounds having multiple different skeletons. Examples of commercially available epoxy resins include liquid epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AD ​​type epoxy resin, polyhydroxybenzene type epoxy resin, polyhydroxynaphthalene type epoxy resin, biphenyl type epoxy resin, and tetramethylbiphenyl type epoxy resin; brominated epoxy resins such as brominated phenol novolac type epoxy resin; solid bisphenol A type epoxy resin, phenol novolac type epoxy resin, bisphenol F novolac type epoxy resin, cresol novolac type epoxy resin, and triphe Examples include nylmethane-type epoxy resins, tetraphenylethane-type epoxy resins, dicyclopentadiene-phenol addition reaction type epoxy resins, phenol aralkyl-type epoxy resins, phenylene ether-type epoxy resins, naphthylene ether-type epoxy resins, naphthol novolac-type epoxy resins, naphthol aralkyl-type epoxy resins, naphthol-phenol copolymer novolac-type epoxy resins, naphthol-cresol copolymer novolac-type epoxy resins, aromatic hydrocarbon formaldehyde resin-modified phenol resin-type epoxy resins, biphenyl-modified novolac-type epoxy resins, etc., which may be used individually or in combination of two or more. The reaction between these epoxy resins and the fatty acids may also be carried out according to known methods and is not particularly limited. Furthermore, some of the raw materials may remain in the resulting reaction product, or it may be purified into a single compound before being used as a dispersant.

[0102] Among these, from the viewpoint of ease of molecular weight adjustment and good reactivity, it is preferable to use compounds obtained by reacting a monofatty acid with a low molecular weight amine compound, compounds obtained by reacting a monofatty acid with a low molecular weight isocyanate compound, and compounds obtained by reacting a monofatty acid with a low molecular weight epoxy resin. In addition, these other dispersants may be used individually or in combination, but it is preferable to use them in a range that does not hinder the effects of the present invention. Specifically, it is preferable that the amount is 100 parts by mass or less, particularly 50 parts by mass or less, and even more preferably 30 parts by mass or less, per 100 parts by mass of compound (B).

[0103] Furthermore, from the viewpoint of suitably applying the dispersion manufacturing method described later, a mixture of the aforementioned compound (B) with a high-viscosity liquid medium beforehand can also be used as a dispersant for the molybdenum disulfide particles (A).

[0104] The high-viscosity liquid medium is not particularly limited as long as it does not react with the molybdenum disulfide particles (A) and the compound (B). For example, the base oil described later may be used as is. Alternatively, high-viscosity resins such as rosins, terpene resins, petroleum resins, coumarone resins, and indene resins can be used. In particular, the use of petroleum resin (C) is preferred from the viewpoint of having better dispersibility in the base oil described later.

[0105] <Method for producing the dispersion> The method for producing the dispersion according to one embodiment of the present invention is not particularly limited as long as the specific molybdenum disulfide particles (A) and the compound (B) can be uniformly mixed, but a so-called media-less dispersion method that does not use pulverizing media such as glass beads or ceramic beads is preferred.

[0106] Generally, when dispersing submicron-sized particles, methods that utilize direct physical forces resulting from collisions between media such as balls or beads and the particles require consideration of the size relationship between the media and the particles. Therefore, uniform dispersion of nanoparticles can sometimes be difficult. Consequently, so-called media-less dispersion methods, which do not use dispersion media such as beads, are preferable. Furthermore, media-less dispersion methods do not require a process to separate the resulting dispersion from the media, making them highly suitable for mass production. Specific examples of such methods include high-pressure homogenizers and jet mills that utilize shear stress in a liquid.

[0107] Dispersion using high-pressure homogenizers and jet mills requires, in principle, to increase the fluid speed to generate kinetic energy. Therefore, it is common to apply pressure and pass the fluid through a nozzle with a diameter of approximately 100 to 1000 μm. However, conventional compositions of molybdenum disulfide particles and dispersants generate aggregates, preventing them from passing through the nozzle and causing clogging. This makes them unsuitable for use in jet mills and poses productivity problems. This is evident, for example, from Patent Document 1, which describes a long ultrasonic treatment process involving the dispersant and a large excess of solvent before high-pressure homogenization. In one embodiment of the present invention, by using the aforementioned compound (B) in combination with specific molybdenum disulfide particles (A), it becomes possible to directly apply a high-pressure homogenizer or jet mill. In addition, premixing may be performed as a pretreatment to facilitate feeding into media-less dispersers such as high-pressure homogenizers and jet mills during the production of the dispersion. Specific examples of such methods include mixing machines, kneaders, planetary mixers, screw mixers, and Huber malas.

[0108] The dispersion conditions in media-less dispersers such as high-pressure homogenizers and jet mills are not particularly limited, but for example, a method in which the material is passed through a pore nozzle with a diameter of 100 to 1000 μm at 1 to 300 MPa is possible, and a method in which the material is passed through a pore nozzle with a diameter of 300 to 500 μm at 10 to 200 MPa is particularly preferred. Furthermore, a method in which the material is passed through a channel having pores is also acceptable, or a method in which a channel having pores is branched and collided with each other is also acceptable.

[0109] <Lubricant Composition> The lubricant composition of one embodiment of the present invention comprises the aforementioned dispersion and base oil as essential components, and various other additives can be added and blended as appropriate depending on the application and desired performance. In this case, since the aforementioned dispersion already has molybdenum disulfide particles (A) uniformly dispersed, the preparation method for commonly used lubricant compositions can be applied, and there is no need to perform any other special preparation, mixing, or dispersion steps. After preparing the lubricant composition, if it is stored for a long period of time by standing, for example, sedimentation may be observed, but when using the dispersion of the present invention, it is possible to easily return to the uniformly dispersed system after preparation by simple stirring, and the generation of excessive aggregates of molybdenum disulfide particles (A) can be suppressed, thereby effectively suppressing deterioration of lubrication performance.

[0110] The aforementioned base oil is not particularly limited, and examples include mineral oil, synthetic oil, or semi-synthetic oil.

[0111] Mineral oils as base oils include, but are not limited to, oils obtained by rock drilling, oils obtained from plants or animals, and mixtures thereof. Examples of such oils include, but are not limited to, castor oil, lard, olive oil, peanut oil, corn oil, soybean oil, linseed oil, liquid petroleum, and paraffinic, naphthenic, or paraffin-naphthenic base oils. Such base oils may be partially or completely hydrogenated if desired.

[0112] Examples of synthetic base oils include polyalphaolefin-based, hydrocarbon-based, ester-based, ether-based, silicone-based, alkylnaphthalene-based, or perfluoroalkyl polyether-based base oils.

[0113] A base oil that is a semi-synthetic oil refers to a base oil that is a mixture of these mineral oils and synthetic oils.

[0114] The aforementioned lubricating composition can use any base oil commonly used in lubricating compositions without limitation.

[0115] The kinematic viscosity of the base oil used in the lubricating composition of this embodiment at 40°C is 10 to 1000 mm². ２ It may also be / s, and 20-500 mm ２ It may also be / s, and 30-200 mm ２ It may also be / s, and 40-150 mm ２ It may also be / s. In the lubricating composition of this embodiment, since the molybdenum disulfide particles (A) are uniformly dispersed by compound (B), even when using a base oil with relatively low viscosity, the settling of the molybdenum disulfide particles (A) can be suppressed.

[0116] The lubricating composition preferably contains 0.0001% to 50% by mass of the molybdenum disulfide particles (A), which are the lubricant, based on 100% by mass of the total mass of the lubricating composition; more preferably, it contains 0.01% to 10% by mass; and particularly preferably, it contains 0.1% to 5% by mass.

[0117] The lubricating composition may further contain known additives such as detergents, viscosity modifiers, anti-foaming agents, corrosion inhibitors, rust inhibitors, antioxidants, anti-wear agents, and friction modifiers.

[0118] Furthermore, the dispersion of this embodiment can also be used in a particle-containing grease composition, and known base oils can be used in this case. For example, naphthenic and / or paraffinic mineral oils (spindle oil, turbine oil, motor oil, brightstock, etc.), synthetic oils (one or more selected from diesters, polyol esters, silicone oils, PFPE (perfluoropolyether), PAO (polyalphaolefin), PAG (polyalkylene glycol), alkyl diphenyl ether, polyphenyl ether, etc.) can be used.

[0119] When used as the aforementioned particle-containing grease composition, a soap-based or non-soap-based thickener can be used. Examples of soap-based thickeners include one or more selected from Ca soap (beef tallow-based or castor oil-based), Li complex soap, Ba complex soap, Al soap, Ca complex, Li complex, Al complex, etc. Examples of non-soap-based thickeners include one or more selected from urea compounds (aromatic diurea, aliphatic or alicyclic diurea, triurea, tetraurea, Na terephthalate, PTFE, bentonite, silica gel, carbon black, etc.).

[0120] Furthermore, when used as the particle-containing grease composition, load-bearing additives may be further included from the viewpoint of reducing frictional wear between friction surfaces and preventing seizing. Examples of load-bearing additives include one or more selected from naphthenic acid Pb, chlorinated paraffin, SP compounds, various metal compounds, phosphorus compounds such as MoDTP and ZnDTP, sulfur compounds, etc.

[0121] Furthermore, since the dispersion, which is one embodiment of the present invention, can be easily dispersed in any liquid medium, it can also be mixed with substances other than the base oil. For example, when an organic solvent or liquid resin is used, it can be suitably used in paints and the like based on molybdenum disulfide particles (A).

[0122] The aforementioned paint is prepared by dispersing molybdenum disulfide particles in a binder solution obtained by dissolving a binder resin in a solvent. Examples of binder resins include polyamide-imide, epoxy resin, furan resin, melamine resin, acrylic resin, and urethane resin, and examples of solvents include xylene, toluene, butanol, isobutyl alcohol, isopropyl alcohol, dioxane, methyl ethyl ketone, and n-methyl-2-pyrrolidone. In addition to the above components, other dispersants different from the dispersant in the present invention, as well as defoamers, stabilizers, flame retardants, curing accelerators, pigments, etc., may be added to the paint as appropriate.

[0123] Various organic solvents can be selected, including alcohol-based, ketone-based, hydrocarbon-based, glycol-based, and aqueous-based solvents. Specifically, examples include alcohol-based solvents such as methanol, ethanol, 1-propanol, isopropanol, butanol, pentanol, benzyl alcohol, and diacetone alcohol; ketone-based solvents such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone; ester-based solvents such as 3-methyl-methoxypropionate; glycol derivatives such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol isopropyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol methyl ether acetate, and propylene glycol ethyl ether acetate; amides such as formamide, N-methylformamide, dimethylformamide, dimethylacetamide, and N-methyl-2-pyrrolidone; aromatic hydrocarbons such as toluene and xylene; and halogenated hydrocarbons such as ethylene chloride and chlorobenzene. These solvents can be used individually or in combination of two or more.

[0124] As the liquid resin, monomers or oligomers that harden by polymerization, such as methyl methacrylate or styrene, or thermoplastic resins dissolved in organic solvents or reactive monomers can be used. In the case of thermoplastic resins, they become fluid above their melting point, so it is possible to mix the dispersion in this embodiment without using other liquid media. Alternatively, the dispersion can be mixed with plasticizers that can be used with these resins, such as triethylene glycol di-2-ethylhexanate, triethylene glycol di-2-ethyl butyrate, or tetraethylene glycol di-2-ethylhexanate.

[0125] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[0126] [Method for measuring the average particle size of primary molybdenum trioxide particles] Molybdenum trioxide particles were imaged using a scanning electron microscope (SEM). For the smallest unit particles constituting the aggregates on the two-dimensional image (i.e., primary particles), their major axis (the Ferret diameter of the longest observed part) and minor axis (the shorter Ferret diameter perpendicular to the Ferret diameter of the longest part) were measured, and the average value of these measurements was taken as the primary particle diameter. The same procedure was performed on 50 randomly selected primary particles, and the average particle size of the primary particles was calculated from the average primary particle diameter of these particles.

[0127] [Purity Measurement of Molybdenum Trioxide: XRF Analysis] Using a Primus IV X-ray fluorescence analyzer (manufactured by Rigaku Corporation), approximately 70 mg of the recovered molybdenum trioxide particle sample was placed on filter paper, covered with a PP film, and subjected to compositional analysis. The amount of molybdenum determined from the XRF analysis results was calculated as molybdenum trioxide (mass%) relative to 100% by mass of molybdenum trioxide particles.

[0128] [Crystal structure analysis: XRD method] The recovered molybdenum trioxide particles or their sulfide samples were packed into a 0.5 mm deep sample holder, which was then placed in a wide-angle X-ray diffraction (XRD) instrument (Ultima IV, manufactured by Rigaku Corporation). Measurements were performed under the following conditions: Cu / Kα rays, 40 kV / 40 mA, scan speed 2 degrees / min, and scan range between 10 and 70 degrees.

[0129] [Specific Surface Area Measurement: BET Method] For samples of molybdenum trioxide particles or molybdenum disulfide particles, the specific surface area was measured using a surface area meter (Microtrac Bell, BELSORP-mini), and the surface area per gram of sample, measured from the amount of nitrogen gas adsorbed by the BET method, was defined as the specific surface area (m²). ２ It was calculated as ( / g).

[0130] [MoS ２ Conversion rate R Ｃ The molybdenum sulfide particles in black powder were measured by X-ray diffraction (XRD). Next, molybdenum disulfide (MoS) was analyzed by the RIR (reference intensity ratio) method. ２ ) RIR value K Ａ and molybdenum sulfide (MoS ２ The integrated intensity I of the peak around 2θ = 14.4° ± 0.5°, which is attributed to the (002) or (003) plane of ). Ａ , and each molybdenum oxide (the raw material is MoO ３ , and the reaction intermediate Mo ９ O ２５ Mo ４ O １１ MoO ２ RIR value K (etc.) Ｂ and each molybdenum oxide (the raw material is MoO ３ , and the reaction intermediate Mo ９ O ２５ Mo ４ O １１ MoO ２ The integrated intensity I of the strongest line peak (etc.) Ｂ Using this, from the following equation (1), MoS ２ Conversion rate R Ｃ We sought R. Ｃ (%) = (I Ａ / K Ａ ) / (Σ(I Ｂ / KＢ )) × 100 ... (1) Here, the RIR values ​​used were those listed in the Inorganic Crystal Structure Database (ICSD), and the analysis was performed using Integrated Powder X-ray Spectroscopy Software (PDXL) (manufactured by Rigaku Corporation).

[0131] [Extensive X-ray Absorption Fine Structure (EXAFS) Measurement] 36.45 mg of molybdenum disulfide powder and 333.0 mg of boron nitride were mixed in a mortar. 123.15 mg of this mixture was weighed out and compressed into a φ8 mm tablet to obtain the measurement sample. Using this measurement sample, the extensive X-ray absorption fine structure (EXAFS) was measured by transmission method at BL5S1 of the Aichi Synchrotron Radiation Center. Analysis was performed using Athena (Internet<URL: https: / / bruceravel.github.io / demeter / > ) was used.

[0132] [Median diameter D of molybdenum disulfide particles] ５０ [Measurement] 0.01 g of molybdenum disulfide powder was added to 20 cc of acetone, and sonicated in an ice bath for 4 hours. Then, the concentration was adjusted with acetone to a level within the measurable range of a dynamic light scattering particle size distribution analyzer (Nanotrac Wave II, manufactured by MicrotracBEL) to obtain a measurement sample. Using this measurement sample, the particle size distribution in the range of 0.0001 μm to 10 μm was measured using a dynamic light scattering particle size distribution analyzer (Nanotrac Wave II, manufactured by MicrotracBEL), and the median diameter D was measured. ５０ The result was calculated.

[0133] [Method for observing the particle shape of molybdenum disulfide particles] Molybdenum disulfide particles were measured using an atomic force microscope (AFM) (Oxford Cypher-ES) to observe their particle shape.

[0134] Synthesis Example 1 Molybdenum trioxide was produced using an RHK simulator (manufactured by Noritake Co., Ltd.) as the firing furnace and a VF-5N dust collector (manufactured by Amano Corporation) as the dust collector. 1.5 kg of aluminum hydroxide (manufactured by Nippon Light Metal Co., Ltd.) and 1 kg of molybdenum trioxide (manufactured by Nippon Muki Co., Ltd.) were mixed, then placed in a sagger, and fired at a temperature of 1100°C for 10 hours. During firing, outside air (airflow rate: 150 L / min, outside air temperature: 25°C) was introduced from the sides and bottom of the firing furnace. After the molybdenum trioxide evaporated in the furnace, it cooled near the dust collector and precipitated as particles, so the molybdenum trioxide (1) was recovered by the dust collector.

[0135] After firing, 1.0 kg of blue aluminum oxide powder and 0.8 kg of molybdenum trioxide (1) recovered by a dust collector were taken from the sac. The median diameter D of the primary particles of the recovered molybdenum trioxide (1) was determined by dynamic light scattering. ５０ The wavelength was 87.8 nm, and the particle shape observed by TEM was ribbon or particulate. By X-ray fluorescence measurement, the purity of molybdenum trioxide (1) was determined (MoO ３ The content ratio was confirmed to be 99.9% by mass.

[0136] Furthermore, when the crystal structure of molybdenum trioxide (1) was analyzed by X-ray diffraction (XRD), peaks attributed to molybdenum trioxide of the α crystal and molybdenum trioxide of the β crystal were observed, and no other peaks were observed. Next, when the peak intensity ratio of the (011) plane of the β crystal and the (021) plane of the α crystal was compared, β(011) / α(021) was found to be 4. In addition, by applying Rigaku Corporation's XRD profile analysis software PDXL Version 2, the XRD instrument constants were determined using LaB6 (NIST SRM660c LaB6 Standard Powder) as a standard material, and the crystallite size was evaluated using the Scherre method. It was confirmed that molybdenum trioxide (1) has a crystal structure containing α crystals with an average crystallite size of 15.7 nm and β crystals with an average crystallite size of 16.8 nm.

[0137] In a mixture of α-crystals and β-crystals of molybdenum trioxide, the content of α-crystals of molybdenum trioxide can be determined from the obtained profile data by the RIR (Reference Intensity Ratio) method. Using the RIR value KA of the α-crystal of molybdenum trioxide and the integrated intensity IA of the (021) plane of the α-crystal of molybdenum trioxide (around 2θ: 27.32°, No. 166363 (Inorganic Crystal Structure Database, ICSD)), as well as the RIR value KB of the β-crystal of molybdenum trioxide and the integrated intensity IB of the (011) plane of the β-crystal of molybdenum trioxide (around 2θ: 23.01°, No. 86426 (Inorganic Crystal Structure Database, ICSD)), the content (%) of α-crystals of molybdenum trioxide can be determined from the following equation (2). The α-crystal content of molybdenum trioxide (%) = (IA / KA) / ((IA / KA) + (IB / KB)) × 100 ... (2) Here, the RIR values ​​can be those listed in the ICSD database, and the integrated powder X-ray analysis software (Rigaku Corporation, PDXL Version 2) can be used for the analysis. The α-crystal content of molybdenum trioxide obtained from equation (2) was 30%.

[0138] Synthesis Example 2 In a magnetic crucible, 450 g of molybdenum trioxide particles obtained in Synthesis Example 1 and 504 g of sulfur powder (manufactured by Kanto Chemical Co., Ltd.) were mixed with a stirring rod until the powders were uniform. The mixture was then fired in a high-temperature atmosphere furnace, after evacuating the furnace and replacing it with nitrogen, at 500°C for 4 hours under a nitrogen atmosphere to obtain black powder. Here, the MoO of the molybdenum trioxide ３ For a total amount of 100 mol%, the sulfur content is 500 mol%. In the X-ray diffraction (XRD) pattern of this black powder, molybdenum disulfide (MoS) ２ Only peaks attributable to ) were detected, and molybdenum disulfide (MoS ２ No peaks not attributed to the by-product molybdenum dioxide (MoO) were observed. ２ No reaction intermediate peaks such as ) were observed, and molybdenum disulfide (MoS ２ Since only peaks attributable to ) were observed, the powder obtained in synthesis example 2 is MoS ２ Conversion rate R Ｃwas 99% or more, and it was confirmed that the reaction with sulfur proceeded rapidly, and it was confirmed that it was composed of molybdenum disulfide particles.

[0139] When the specific surface area of the molybdenum disulfide particles (A-1) obtained in Synthesis Example 2 was measured by the BET method, it was 108 m ２ / g. 3R / 2H obtained by Rietveld analysis in XRD measurement was 1.5. Also, the particle size distribution of the molybdenum disulfide particles was measured with a dynamic light scattering particle size distribution measuring device, and the median diameter D ５０ was determined to be 260 nm. Furthermore, its thickness was measured with an AFM manufactured by Oxford Cypher-ES. The aspect ratio calculated from the median diameter D ５０ and the particle thickness obtained from AFM was 8.

[0140] Synthesis Example 3 Molybdenum disulfide particles (A-2) were obtained in the same manner as in Synthesis Example 2, except that the firing temperature was changed to 380 °C and the firing time was changed to 4 hours. The specific surface area was 40 m ２ / g, the 3R / 2H was 0.25, and the aspect ratio was 5.

[0141] Examples 1 to 2, Comparative Examples 1 to 5 Dispersions and lubricating compositions were prepared in the following steps using the materials shown in Table 1. Step 1-1: Dispersion 1 part by mass of molybdenum disulfide particles and 2 parts by mass of a dispersant were mixed with an automatic Hoover mixer manufactured by Toyo Seiki Seisakusho (test load 68.04 kg, rotation speed 100 rpm, 1 minute). Step 2-2: Lubricating composition 9 parts by mass of the dispersion obtained in Step 1-1 was diluted with 10,000 parts by mass of a base oil (YUBASE4, Group III mineral oil), and ultrasonic dispersion (output 500 W, frequency 40 kHz) was performed at 25 to 30 °C for 1 minute.

[0142] Ten mL of the obtained lubricating composition was placed in a 20 mL glass bottle and allowed to stand at room temperature (25°C) for 7 and 30 days. After that, the glass bottle was inverted and the dispersion stability was visually evaluated by the degree of sedimentation of the precipitate that had accumulated at the bottom of the bottle. The lubricating composition is black because it contains a high degree of molybdenum disulfide particle dispersion, and it is necessary to invert the glass bottle to observe the precipitate. (The less sedimentation, the better the dispersion stability). The symbols in the table have the following meanings. The results are shown in Table 1. ◎...Excellent, ○...Good, △...Acceptable, ×...Poor, ××...Very poor Excellent: No precipitate at all at the bottom of the bottle Good: Almost no precipitate at the bottom of the bottle Acceptable: A small amount of precipitate at the bottom of the bottle Poor: Pretty clear precipitate at the bottom of the bottle Very poor: Precipitation is clearly visible at the bottom of the bottle without even having to invert the glass bottle

[0143]

[0144] M-5 powder: Molybdenum disulfide manufactured by Daizo. Measurements were taken in the same manner as in the synthesis example, and the specific surface area was 8 m². ２ The ratio was / g, 3R / 2H was 0.03, and the aspect ratio was 0.9. Succinimide 1: A mixture of the reaction product of polyethylene polyamine and (polyisobutenyl derivative of succinic anhydride) (CAS number 84605-20-9) and a hydrogenated heavy paraffinic petroleum fraction (CAS number 64742-54-7). Active ingredient concentration: 75% by mass. Sulfonate 1: 3-[dimethyl(octadecyl)ammonio]propane-1-sulfonate

[0145] Examples 3-10, Comparative Examples 6-13 Dispersions and lubricating compositions were prepared using the materials shown in Tables 2-3 in the following steps. Step 1-1: Premixing One part by mass of molybdenum disulfide particles and two parts by mass of the compound used as a dispersant were mixed using an automatic Huber marler manufactured by Toyo Seiki Seisakusho (test load 68.04 kg, rotation speed 100 rpm, 1 minute). Step 1-2: High-pressure homogenizer The mixture obtained in Step 1-1 was dispersed using a high-pressure homogenizer NAGS20 manufactured by Joko Co., Ltd. (nozzle diameter 300 μm) at a discharge pressure of ≤65 MPa to obtain a dispersion. Step 2-2: Lubrication composition. Nine parts by mass of the dispersion obtained in Step 1-2 were diluted with 10,000 parts by mass of base oil (YUBASE 4, Group III mineral oil), and ultrasonic dispersion (output 500 W, frequency 40 kHz) was performed at 25-30°C for 1 minute.

[0146] In steps 1-2, the presence or absence of clogging in the high-pressure homogenizer was checked. If there was no clogging, it could be judged that the productivity and mass production capabilities were excellent. Furthermore, the dispersion stability of the obtained lubricating composition was visually evaluated using the same method as in Examples 1-2. The results are shown in Tables 2-3.

[0147]

[0148]

[0149] Succinimide 2: A mixture of borate (CAS No. 134758-95-5), a reaction product of polyethylene polyamine and (a polyisobutenyl derivative of succinic anhydride), and a hydrogenated heavy paraffinic petroleum fraction (CAS No. 64742-54-7). Active ingredient concentration: 60% by mass. Benzesulfonate 1: A mixture of calcium salt of alkyl (C=16-24) benzenesulfonic acid (CAS No. 70024-69-0) and a hydrogenated heavy paraffinic petroleum fraction (CAS No. 64742-54-7). Active ingredient concentration: 55% by mass. Salicylate 1: Calcium salt of 2 [alkyl (C=14-18)-2-hydroxybenzoic acid] (2:1) (CAS No. 114959-46-5)

[0150] Examples 11-16, Comparative Examples 14-17: The lubricating compositions obtained in Examples 3, 5, 6, 7, 9, 10, and Comparative Examples 8, 10, 12, 13 were subjected to SRV testing using an SRV5 manufactured by Parker Heat Treatment Industries Co., Ltd., with a surface pressure of 400 N, a measurement frequency of 50 Hz, and an amplitude of 1.5 mm. A 100Cr6 disc with a diameter of 24 mm and a thickness of 7.9 mm was used as the lower substrate, and a 100Cr6 cylinder with a diameter of 15 mm and a length of 15 mm was used as the upper substrate. The values ​​measured after sliding at 40°C for 7 minutes and 30 seconds are shown in Table 4.

[0151]

[0152] 1...Manufacturing equipment, 2...Firing furnace, 3...Cooling piping, 4...Recovery machine, 5...Exhaust port, 6...Opening adjustment damper, 7...Observation window, 8...Air exhaust device, 9...External cooling device.

Claims

1. Specific surface area is 40 m² ２ A dispersion containing molybdenum disulfide particles (A) at a concentration of 1 / g or more, and one or more compounds (B) selected from the group consisting of compounds having secondary nitrogen and organic acid salts.

2. The dispersion according to claim 1, wherein the compound (B) is one or more compounds (B1) selected from the group consisting of compounds having a substituted succinimide group and a group containing a secondary nitrogen, alkylbenzene sulfonates, and alkyl salicylates.

3. The dispersion according to claim 1, wherein the molybdenum disulfide particles (A) have a 3R / 2H ratio, which is the ratio of 3R crystal structure to 2H crystal structure, of 0.25 or more.

4. The dispersion according to claim 1, wherein the dispersant (B) is a compound having a 3-polyalkenylpyrrole-2,5-dione-1-yl group.

5. The dispersant (B) is the following general formula (1) [In formula (1), R represents a polyalkenyl group, and n represents an integer of 1 or more, R １ The dispersion according to claim 1, wherein represents an n-valent organic group containing secondary nitrogen.

6. The dispersion according to claim 5, wherein R in formula (1) is a polyisobutenyl group.

7. The dispersion according to claim 1, wherein the ratio of molybdenum disulfide particles (A) to compound (B) is in the range of 10 to 500 parts by mass per 100 parts by mass of molybdenum disulfide particles (A).

8. The dispersion according to claim 1, further containing petroleum resin (C).

9. A lubricating composition comprising a dispersion according to any one of claims 1 to 8 and a base oil.

10. Specific surface area of ​​40 m² ２ A method for producing a dispersion, comprising dispersing molybdenum disulfide particles (A) at a concentration of 1 / g or more, and one or more compounds (B) selected from the group consisting of compounds having secondary nitrogen and organic acid salts, using medialess dispersion.

11. The method for producing a dispersion according to claim 10, wherein the compound (B) is one or more compounds (B1) selected from the group consisting of compounds having a substituted succinimide group and a group containing a secondary nitrogen, alkylbenzene sulfonates, and alkyl salicylates.

12. After mixing one or more compounds (B) selected from the group consisting of compounds having secondary nitrogen and organic acid salts with petroleum resin (C), the specific surface area is further reduced to 40 m². ２ A method for producing a dispersion, comprising adding molybdenum disulfide particles (A) at a concentration of 1g or more and forming a dispersion using medialess dispersion.

13. The method for producing a dispersion according to claim 12, wherein the compound (B) is one or more compounds (B1) selected from the group consisting of compounds having a substituted succinimide group and a group containing a secondary nitrogen, alkylbenzene sulfonates, and alkyl salicylates.

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