WO2025225467A1 - Method for producing molybdenum dithiocarbamate, molybdenum dithiocarbamate obtained by said production method, and lubricating oil composition or grease composition containing said molybdenum dithiocarbamate - Google Patents

Abstract

The present invention relates to a method for producing molybdenum dithiocarbamate comprising: a DTC formation step for obtaining a DTC intermediate by reacting one or more molybdenum compounds selected from the group consisting of molybdic acid and salts thereof, a sulfur source containing octasulfur and carbon disulfide, and an amine compound represented by general formula (1); and a reduction step for reducing the resulting DTC intermediate in the presence of a reducing agent to obtain molybdenum dithiocarbamate represented by general formula (2). The present invention also relates to molybdenum dithiocarbamate obtained by the production method. Formula (1) (In the formula, R¹-R² each independently represent a C4-14 hydrocarbon group.)　Formula (2) (In the formula, R³-R⁶ each independently represent a C4-14 hydrocarbon group, and X¹-X⁴ each independently represent an oxygen atom or a sulfur atom.)

Description

Method for producing molybdenum dithiocarbamate, molybdenum dithiocarbamate obtained by said method, and lubricating oil or grease composition containing said molybdenum dithiocarbamate

The present invention relates to a method for producing molybdenum dithiocarbamate, which can produce molybdenum dithiocarbamate with a high sulfur content in high yield.

In the automotive sector, regulations on fuel economy and exhaust gas emissions, as well as regulations stemming from environmental issues such as global warming, air pollution, and acid rain, as well as the need to protect finite resources such as petroleum energy, are becoming stricter every year. To address these issues, for example, in order to improve the fuel efficiency of automobiles, not only are improvements to the automobile itself, such as reducing the weight of the car body and improving the engine, but improvements to engine oils, such as lowering the viscosity of engine oil to prevent friction loss in the engine and adding good friction modifiers, are also important. Among friction modifiers, molybdenum dithiocarbamate has excellent lubricating properties and friction-reducing effects, and is also less corrosive to metals, so it is added to a variety of lubricating oils.

Patent Document 1 describes a method for producing molybdenum dithiocarbamate in which carbon disulfide and a secondary amine are added to an aqueous solution of molybdenum trioxide or an alkali metal salt of molybdic acid combined with an alkali hydrosulfide or alkali sulfide and having a pH of 8.5 to 11.

Furthermore, Patent Document 2 describes a method for producing highly sulfurized molybdenum dithiocarbamate, which is believed to provide good antioxidant stability and improved antifriction retention properties, comprising the steps of reacting a metal source, water, at least one reagent amine, and carbon disulfide under pressure at a temperature higher than the normal boiling point of carbon disulfide.

Japanese Patent Application Publication No. 4-182494 Special Publication No. 2009-512735

The method described in Patent Document 1 is said to produce an organo-molybdenum compound with a relatively high sulfur content compared to conventional organo-molybdenum compounds, but there are problems with the purity and yield of the resulting product being insufficient.

The method described in Patent Document 2 produces molybdenum dithiocarbamate with a high sulfur content, which is believed to have excellent properties. However, the method described in Patent Document 2 requires special equipment for carrying out the reaction under a heated and pressurized environment, and therefore there has been a need for the development of a simpler method for producing molybdenum dithiocarbamate with a high sulfur content.

Therefore, an object of the present invention is to provide a method for producing molybdenum dithiocarbamate that can produce molybdenum dithiocarbamate with a high sulfur content in high yield.

As a result of extensive research aimed at solving the above-mentioned problems, the inventors discovered that a production method having specific steps can produce molybdenum dithiocarbamate with a high sulfur content in high yield, and thus completed the present invention. Specifically, the present invention is a method for producing molybdenum dithiocarbamate, comprising: a DTC conversion step in which one or more molybdenum compounds selected from the group consisting of molybdic acid and its salts, a sulfur source including octasulfur and carbon disulfide, and an amine compound represented by the following general formula (1) are reacted to obtain a DTC intermediate; and a reduction step in which the obtained DTC intermediate is reduced in the presence of a reducing agent to obtain molybdenum dithiocarbamate represented by the following general formula (2).

(In the formula, R ¹ and R ² each independently represent a hydrocarbon group having 4 to 14 carbon atoms.)

(wherein R ³ to R ⁶ each independently represent a hydrocarbon group having 4 to 14 carbon atoms, and X ¹ to X ⁴ each independently represent an oxygen atom or a sulfur atom.)

The present invention provides a method for producing molybdenum dithiocarbamate that can produce molybdenum dithiocarbamate with a high sulfur content in high yield.

A. Method for Producing Molybdenum Dithiocarbamate Hereinafter, the method for producing the molybdenum dithiocarbamate of the present invention will be described.

A1. DTC Formation Step The DTC formation step in the method for producing molybdenum dithiocarbamate of the present invention is a step of reacting one or more molybdenum compounds selected from the group consisting of molybdic acid and its salts, a sulfur source containing octasulfur and carbon disulfide, and an amine compound represented by general formula (1) to obtain a DTC (dithiocarbamate) intermediate.

(1) Molybdenum Compound In the present invention, the molybdenum compound used in the DTC formation step is one or more selected from the group consisting of molybdic acid and its salts. Examples of molybdic acid include molybdenum trioxide and molybdenum trioxide hydrate. Examples of molybdic acid salts include ammonium molybdate, sodium molybdate, potassium molybdate, sodium hydrogen molybdate, molybdic acid chloride, molybdic acid bromide, and molybdic heteropolyacid. One or more of these can be used. In the present invention, among these, it is preferable to use one or more molybdenum compounds selected from the group consisting of molybdenum trioxide, molybdenum trioxide hydrate, sodium molybdate, and potassium molybdate. It is even more preferable to use one or more molybdenum compounds selected from the group consisting of molybdenum trioxide and molybdenum trioxide hydrate.

(2) Sulfur Source In the present invention, the sulfur source used in the DTC formation step is a sulfur source containing octasulfur and carbon disulfide. Octasulfur is an inorganic compound composed of eight sulfur elements, represented by the chemical formula _S8 , and its CAS number is 10544-50-0. In the present invention, by using octasulfur and carbon disulfide in combination, molybdenum dithiocarbamate with a high sulfur content can be easily obtained in high yield. Other sulfur sources, such as polysulfide compounds, can also be used in the DTC formation step. However, from the viewpoint of easily obtaining molybdenum dithiocarbamate with a high sulfur content in high yield, the total sulfur content of octasulfur and carbon disulfide in the sulfur source is preferably 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass (the sulfur source is composed of octasulfur and carbon disulfide) based on the total sulfur content in the sulfur source. The ratio of octasulfur to carbon disulfide used as the sulfur source is not particularly limited, but from the viewpoint of facilitating the production of molybdenum dithiocarbamate with a high elemental sulfur content in high yield, it is preferable to adjust the mass ratio of the octasulfur to carbon disulfide so that the mass ratio of the elemental sulfur content of the octasulfur to the elemental sulfur content of carbon disulfide is 10:90 to 90:10. The mass ratio of the elemental sulfur content of the octasulfur to the elemental sulfur content of carbon disulfide is more preferably 20:80 to 80:20, even more preferably 30:70 to 70:30, and particularly preferably 40:60 to 60:40.

In this DTC process, by using octasulfur in addition to carbon disulfide, which is conventionally used as a sulfur source, it is believed that DTC intermediates such as those represented by the following general formulas (3) to (5) can be easily and efficiently obtained, and it is believed that it is particularly easy to obtain a DTC intermediate represented by general formula (5) with a high sulfur content.

(In the formula, R ⁷ to R ¹⁰ each independently represent a hydrocarbon group having 4 to 14 carbon atoms.)

(In the formula, R ¹¹ to R ¹⁴ each independently represent a hydrocarbon group having 4 to 14 carbon atoms.)

(In the formula, R ¹⁵ to R ¹⁸ each independently represent a hydrocarbon group having 4 to 14 carbon atoms.)

Examples of the hydrocarbon group having 4 to 14 carbon atoms represented by R ⁷ to R ¹⁰ in general formula (3), R ¹¹ to R ¹⁴ in general formula (4), and R ¹⁵ to R ¹⁸ in general formula (5) respectively include linear alkyl groups such as n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-unsil group, n-dodecyl group, n-tridecyl group, and n-tetradecyl group; secondary butyl group, isobutyl group, secondary pentyl group, isopentyl group, secondary hexyl group, isohexyl group, secondary heptyl group, isoheptyl group, secondary octyl group, isooctyl group, secondary nonyl group, isononyl group, secondary decyl group, isodecyl group, and secondary undecyl group; Examples of suitable hydrocarbon groups include branched alkyl groups such as isoundecyl, secondary dodecyl, isododecyl, secondary tridecyl, isotridecyl, secondary tetradecyl, and isotetradecyl, unsaturated hydrocarbon groups such as butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, and tetradecenyl, alicyclic hydrocarbon groups such as cyclohexyl, methylcyclohexyl, dimethylcyclohexyl, and ethylcyclohexyl, and aromatic hydrocarbon groups such as phenyl and benzyl. R to ^R in general formula (3), ^R to ^R in general formula ( ⁴ ), and R to ^R in general formula (5) ^each correspond to the structure of the hydrocarbon group of the amine compound used in the DTC formation step.

(3) Amine Compound In the present invention, the amine compound used in the DTC formation step is an amine compound having a hydrocarbon group having 4 to 14 carbon atoms and represented by the following general formula (1):

In general formula (1), R ¹ and R ² each independently represent a hydrocarbon group having 4 to 14 carbon atoms. Examples of the hydrocarbon group having 4 to 14 carbon atoms include linear alkyl groups such as n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-unsyl, n-dodecyl, n-tridecyl, and n-tetradecyl groups; secondary butyl, isobutyl, secondary pentyl, isopentyl, secondary hexyl, isohexyl, secondary heptyl, isoheptyl, secondary octyl, isooctyl, secondary nonyl, isononyl, secondary decyl, isodecyl, secondary undecyl, and isoonyl. Examples of such groups include branched alkyl groups such as a decyl group, a secondary dodecyl group, an isododecyl group, a secondary tridecyl group, an isotridecyl group, a secondary tetradecyl group, and an isotetradecyl group; unsaturated hydrocarbon groups such as a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, and a tetradecenyl group; alicyclic hydrocarbon groups such as a cyclohexyl group, a methylcyclohexyl group, a dimethylcyclohexyl group, and an ethylcyclohexyl group; and aromatic hydrocarbon groups such as a phenyl group and a benzyl group. The amine compound used in the DTC formation step may be an amine compound of general formula (1) in which ^R1 and ^R2 are the same hydrocarbon group, or an amine compound in which ^R1 and ^R2 are different hydrocarbon groups, but from the viewpoint of facilitating the production of a molybdenum dithiocarbamate with a high sulfur content in high yield, it is preferable to use an amine compound in which ^R1 and ^R2 are the same hydrocarbon group. Furthermore, in the DTC formation step, one type of amine compound or two or more types of amine compounds may be used.

In the present invention, from the viewpoint of facilitating the production of molybdenum dithiocarbamate having a high sulfur content in high yield, the amine compound used in the DTC formation step is preferably an amine compound represented by general formula (1) in which R ¹ and R ² are each independently a linear alkyl group having 4 to 14 carbon atoms or a branched alkyl group having 4 to 14 carbon atoms, more preferably an amine compound in which R ¹ and R ² are each independently a linear alkyl group having 8 to 13 carbon atoms or a branched alkyl group having 8 to 13 carbon atoms, even more preferably an amine compound in which R ¹ and R ² are each independently a linear alkyl group having 8 or 13 carbon atoms or a branched alkyl group having 8 or 13 carbon atoms, and particularly preferably an amine compound in which R ¹ and R ² are each independently a branched alkyl group having 8 or 13 carbon atoms.

(4) Organic Solvent In addition, from the viewpoint of facilitating the production of molybdenum dithiocarbamate having a high sulfur content in a higher yield, the DTC step is preferably carried out by mixing the molybdenum compound, sulfur source, and amine compound in the presence of an organic solvent which is a monohydric alcohol having 3 to 8 carbon atoms and which has a Hansen solubility parameter dispersion term δd of 15.0 to 17.5 (MPa) ^1/2 , a dipolar term δp of 0 to 6.8 (MPa) ^1/2 , and a hydrogen bond term δh of 10.0 to 17.5 (MPa) ^1/2 . Examples of such organic solvents that are monohydric alcohols having 3 to 8 carbon atoms include aliphatic alcohols such as 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butyl alcohol, 1-pentanol, 2-pentanol, 3-methyl-1-butanol, 2-methyl-2-butanol, 1-hexanol, 2-hexanol, cyclohexanol, 2-methyl-2-pentanol, 3-methyl-1-pentanol, 1-heptanol, 2-heptanol, 1-octanol, 2-octanol, and 2-ethylhexanol. Examples of suitable organic solvents include glycol ethers such as ethanol, ethylene glycol monobutyl ether, ethylene glycol mono-n-hexyl ether, ethylene glycol mono-2-ethylhexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monoisopropyl ether, propylene glycol mono-t-butyl ether, dipropylene glycol mono-n-propyl ether, and tripropylene glycol monomethyl ether, and one or more of these can be used. In the present invention, the use of such an organic solvent in the DTC formation step can improve the reactivity of the molybdenum compound with the sulfur source and the amine compound, thereby enabling the DTC formation intermediate to be obtained more efficiently and, as a result, enabling the production of molybdenum dithiocarbamate with a high sulfur content in high yield.

Furthermore, in the present invention, the use of an organic solvent having a boiling point of 110°C or higher as the organic solvent is preferred, since this can prevent evaporation of the organic solvent and destabilization of the system during the reaction, allowing the target reaction to proceed stably, and enabling the production of molybdenum dithiocarbamate with a high elemental sulfur content more easily. Among the organic solvents described above, in the present invention, from the viewpoint of easily and efficiently obtaining a DTC intermediate and a molybdenum dithiocarbamate with a high elemental sulfur content, the organic solvent preferably has a Hansen solubility parameter of 15.0 to 16.5 (MPa) ^1/2 for the dispersion term δd, 3.0 to 6.5 (MPa) ^1/2 for the dipolar term δp, and 11.0 to 17.0 (MPa) It is more preferable to use a monohydric alcohol having 3 to 8 carbon atoms, where the ratio is ^1/2 , and it is more preferable to use one or more selected from the group consisting of 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-hexanol, 2-hexanol, cyclohexanol, 2-ethylhexanol, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether. It is even more preferable to use one or more selected from the group consisting of 1-propanol, 2-propanol, 1-butanol, 2-butanol, cyclohexanol, 2-ethylhexanol, 2-butanol, and propylene glycol monomethyl ether, and it is particularly preferable to use 1-butanol. In the present invention, the dispersion term δd representing the London dispersion energy, the polar term δp representing the dipole-dipole interaction energy, and the hydrogen bond term δh representing the hydrogen bond energy in the Hansen solubility parameters are values calculated by the van Krevelen & Hoftyzer method based on the atomic group contribution method.

(5) Reaction Conditions The DTC formation step in the present invention is a step of reacting the molybdenum compound, sulfur source, and amine compound described above. The ratio of the raw materials used in the DTC formation step is not particularly limited, and can be adjusted appropriately as long as it results in a DTC intermediate. In this case, the raw materials may be added in their entirety at once and reacted, or may be added in two or more portions and reacted. The conditions for reacting the molybdenum compound, sulfur source, and amine compound are also not particularly limited, and any reaction temperature and reaction time may be used as long as a DTC intermediate is obtained. For example, the reaction temperature is preferably 10 to 100°C, more preferably 20 to 70°C, and even more preferably 20 to 50°C. The reaction time is preferably 30 minutes to 15 hours, more preferably 1 to 10 hours.

(6) Molar Equivalent Ratio of Each Element and Amine In the DTC formation step, from the viewpoint of easily obtaining a molybdenum dithiocarbamate having a high sulfur content in high yield, the molar equivalent ratio (Mo:S) of the Mo element contained in the molybdenum compound to the S element contained in the sulfur source is preferably 1:1.5 to 1:10, more preferably 1:2 to 1:8, even more preferably 1:3 to 1:6, and particularly preferably 1:4 to 1:5. In this case, from the viewpoint of facilitating the production of a molybdenum dithiocarbamate having a high sulfur content in high yield, the molar equivalent ratio of Mo contained in the molybdenum compound used, S contained in the octasulfur compound used as the sulfur source, and S contained in the carbon disulfide is preferably 1:0.2-5:0.1-6, more preferably 1:0.8-4:1-5, even more preferably 1:1-3:1.1-4, and particularly preferably 1:1.2-2.5:1.2-3.

In the DTC conversion process, from the viewpoint of facilitating the production of a high yield of molybdenum dithiocarbamate with a high sulfur content, the molar equivalent ratio of Mo contained in the molybdenum compound used to the amine compound (Mo:amine) is preferably 1:0.8 to 1:2, more preferably 1:1 to 1:1.5, even more preferably 1:1.01 to 1:1.3, and particularly preferably 1:1.02 to 1:1.2.

In the DTC conversion process, from the viewpoint of facilitating the production of a high yield of molybdenum dithiocarbamate with a high sulfur content, the molar equivalent ratio of the sulfur element contained in the sulfur source used to the amine compound (S:amine) is preferably 10:2 to 1.5:0.8, more preferably 8:1 to 1:1.5, even more preferably 6:1.01 to 3:1.3, and particularly preferably 5:1.02 to 5:1.2.

In the DTC conversion process, from the viewpoint of facilitating the production of a high yield of molybdenum dithiocarbamate with a high sulfur content, the molar equivalent ratio (Mo:S:amine) of the Mo element contained in the molybdenum compound used, the S element contained in the sulfur source, and the amine compound, where the molar equivalent of Mo is taken as 1, is preferably 1:1.5-10:0.8-2, more preferably 1:2-8:1-1.5, even more preferably 1:3-6:1.01-1.3, and particularly preferably 1:4-5:1.02-1.2.

(7) Molar Equivalent Ratio of Each Element and Amine to Organic Solvent When the DTC conversion step is carried out in the presence of the above-mentioned organic solvent, from the viewpoint of easily obtaining a molybdenum dithiocarbamate having a high sulfur content in high yield, the molar equivalent ratio of the S element contained in the sulfur source used to the organic solvent (S:organic solvent) is preferably 10:0.05 to 1.5:10, more preferably 8:0.1 to 2:5, even more preferably 6:0.2 to 3:3, and particularly preferably 5:0.3 to 4:2.

When the DTC conversion step is carried out in the presence of the organic solvent described above, from the viewpoint of facilitating the production of a high yield of molybdenum dithiocarbamate with a high sulfur content, the molar equivalent ratio of the amine compound used to the organic solvent (amine:organic solvent) is preferably 2:0.05 to 0.8:10, more preferably 1.5:0.1 to 1:5, even more preferably 1.3:0.2 to 1.01:3, and particularly preferably 1.2:0.3 to 1.02:2.

When the DTC conversion step is carried out in the presence of the organic solvent described above, from the viewpoint of facilitating the production of a high yield of molybdenum dithiocarbamate with a high sulfur content, the molar equivalent ratio of Mo contained in the molybdenum compound used to the organic solvent (Mo:organic solvent) is preferably 1:0.05 to 1:10, more preferably 1:0.1 to 1:5, even more preferably 1:0.2 to 1:3, and particularly preferably 1:0.3 to 1:2.

When the DTC conversion step is carried out in the presence of the organic solvent described above, from the viewpoint of facilitating the production of a high yield of molybdenum dithiocarbamate with a high sulfur content, the molar equivalent ratio (Mo:S:amine:organic solvent) of the Mo element contained in the molybdenum compound used, the S element contained in the sulfur source, the amine compound, and the organic solvent, where the molar equivalent of Mo is taken as 1, is preferably 1:1.5-10:0.8-2:0.05-10, more preferably 1:2-8:1-1.5:0.1-5, even more preferably 1:3-6:1.01-1.3:0.2-3, and particularly preferably 1:4-5:1.02-1.2:0.3-2.

A2. Reduction Step The reduction step in the method for producing molybdenum dithiocarbamate of the present invention is a step in which the DTC intermediate obtained in the above-mentioned DTC step is reduced in the presence of a reducing agent to obtain a molybdenum dithiocarbamate represented by the following general formula (2):

(wherein R ³ to R ⁶ each independently represent a hydrocarbon group having 4 to 14 carbon atoms, and X ¹ to X ⁴ each independently represent an oxygen atom or a sulfur atom.)

(1) Reducing Agent In the present invention, the reducing agent used in the reduction step is not particularly limited as long as it is a compound that can cause a reduction reaction of the DTC intermediate. Examples of the reducing agent include alkali sulfides such as sodium sulfide, sodium polysulfide, potassium sulfide, and ammonium sulfide; alkali hydrosulfides such as sodium hydrosulfide and potassium hydrosulfide; hydrides such as hydrogen iodide, hydrogen sulfide, and sodium borohydride; salts of lower oxygen acids such as sodium sulfite, sodium dithionite, sodium dithionite (hydrosulfide), sodium hydrogensulfite, sodium pyrosulfite, and sodium thiosulfate; salts of metals in a low valence state such as iron(II), tin(II), titanium(III), and chromium(II); aldehydes such as formaldehyde and acetaldehyde; hydrazine, borane, diborane, formic acid, oxalic acid, and ascorbic acid. One or more of these may be used. In the present invention, among these, from the viewpoint of facilitating the production of molybdenum dithiocarbamate having a high sulfur content ratio in high yield, it is preferable to use one or more selected from the group consisting of alkali sulfides, alkali hydrosulfides, and salts of lower oxygen acids, it is more preferable to use one or more selected from the group consisting of alkali hydrosulfides and salts of lower oxygen acids, it is even more preferable to use one or more selected from the group consisting of sodium hydrosulfide, potassium hydrosulfide, sodium pyrosulfite, and sodium thiosulfate, and it is particularly preferable to use sodium hydrosulfide.
When sodium hydrate is used as the reducing agent, it is preferably used in the form of a 10% to 70% aqueous solution from the viewpoint of safety.

The amount of reducing agent used in the reduction step is not particularly limited, as long as it is an amount that can reduce the DTC intermediate obtained in the DTC step described above. However, from the perspective of easily obtaining a high yield of molybdenum dithiocarbamate with a high sulfur content, the amount of reducing agent is preferably 0.5 to 3 moles, more preferably 1 to 2.5 moles, even more preferably 1.2 to 2.2 moles, and particularly preferably 1.4 to 2 moles, per mole of Mo contained in the DTC intermediate.

(2) Reaction Conditions The reduction step in the present invention is a step in which the DTC intermediate obtained in the above-described DTC step is reduced in the presence of a reducing agent. In this step, the reduction temperature is not particularly limited and can be adjusted as appropriate. However, from the viewpoint of easily obtaining a molybdenum dithiocarbamate having a high sulfur content in high yield, the reduction temperature is preferably 40°C to 120°C, more preferably 60°C to 110°C, and even more preferably 70°C to 100°C. Furthermore, the reduction time is not particularly limited and can be adjusted as appropriate. However, from the viewpoint of efficiently obtaining a molybdenum dithiocarbamate having a high sulfur content in high yield, reduction is preferably carried out for 0.5 to 20 hours, and more preferably for 1 to 10 hours.

In the present invention, by carrying out such a reduction step, it is possible to obtain the molybdenum dithiocarbamate represented by general formula (2) in high yield from the above-mentioned DTC intermediate, and in particular, it is possible to easily obtain in high yield a molybdenum dithiocarbamate with a high sulfur content, which is considered to have excellent properties among the molybdenum dithiocarbamates represented by general formula (2). Here, a molybdenum dithiocarbamate with a high sulfur content is a molybdenum dithiocarbamate in which the ratio of sulfur atoms in X ¹ to X ⁴ in general formula (2) is high, for example, a molybdenum dithiocarbamate in which the ratio of the number of oxygen atoms to the number of sulfur atoms in X ¹ to X ⁴ is 1.8 to 0:2.2 to 4.

A3. Other Steps In addition to the DTC formation step and reduction step described above, the method for producing molybdenum dithiocarbamate of the present invention may include other steps, such as a dehydration step, a reflux step, and a purification step, depending on the purpose. Furthermore, in the present invention, in the DTC formation step, reduction step, and other steps, the solution may be neutralized by adding an acid such as hydrochloric acid, nitric acid, nitrous acid, sulfuric acid, sulfurous acid, phosphoric acid, phosphorous acid, or perchloric acid. In the present invention, from the viewpoint of obtaining a molybdenum dithiocarbamate having a high sulfur content in high yield, at least one acid selected from the group consisting of hydrochloric acid, nitric acid, and sulfuric acid is added in the DTC formation step or reduction step in an amount that is 0.001 to 2.0 moles, and more preferably 0.01 to 1.0 moles, where the molar equivalent of Mo contained in the molybdenum compound used is taken as 1. In this case, the acid may be added in the form of an aqueous solution, if necessary.

B. Molybdenum Dithiocarbamate The molybdenum dithiocarbamate of the present invention is a molybdenum dithiocarbamate represented by the following general formula (2), which is obtained by the above-described method for producing molybdenum dithiocarbamate.

In general formula (2), R ³ to R ⁶ each independently represent a hydrocarbon group having 4 to 14 carbon atoms. Examples of such hydrocarbon groups having 4 to 14 carbon atoms include linear alkyl groups such as n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-unsyl, n-dodecyl, n-tridecyl, and n-tetradecyl groups; secondary butyl, isobutyl, secondary pentyl, isopentyl, secondary hexyl, isohexyl, secondary heptyl, isoheptyl, secondary octyl, isooctyl, secondary nonyl, isononyl, secondary decyl, and isodesyl groups. branched alkyl groups such as a butenyl group, a secondary undecyl group, an isoundecyl group, a secondary dodecyl group, an isododecyl group, a secondary tridecyl group, an isotridecyl group, a secondary tetradecyl group, and an isotetradecyl group; unsaturated hydrocarbon groups such as a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, and a tetradecenyl group; alicyclic hydrocarbon groups such as a cyclohexyl group, a methylcyclohexyl group, a dimethylcyclohexyl group, and an ethylcyclohexyl group; and aromatic hydrocarbon groups such as a phenyl group and a benzyl group.

In general formula (2), X ¹ to X ⁴ each independently represent an oxygen atom or a sulfur atom. In this case, the ratio of the number of oxygen atoms to the number of sulfur atoms in X ¹ to X ⁴ is not particularly limited and can be adjusted depending on the purpose, but from the viewpoint of various properties such as the friction-reducing properties of the molybdenum dithiocarbamate, the ratio of the number of oxygen atoms to the number of sulfur atoms in X ¹ to X ⁴ is preferably 1.8 to 0:2.2 to 4, more preferably 1.7 to 0:2.3 to 4, even more preferably 1.2 to 0:2.8 to 4, and particularly preferably 1 to 0.4:3 to 3.6.

The molybdenum dithiocarbamate of the present invention can be used in any application that conventional molybdenum dithiocarbamates are used for, without any particular limitation. For example, it can be used in lubricating oils such as engine oil, gear oil, turbine oil, hydraulic oil, flame-retardant hydraulic fluid, refrigeration oil, compressor oil, vacuum pump oil, bearing oil, insulating oil, slideway oil, rock drill oil, metal processing oil, plastic processing oil, and heat treatment oil; and greases such as bearing grease, gear grease, joint grease, and bearing grease.

C. Lubricating Oil Composition When the molybdenum dithiocarbamate of the present invention is added to a base oil to be used as a lubricating oil composition, the amount of molybdenum dithiocarbamate blended is not particularly limited, but from the viewpoint of making it easier to exhibit the properties of the molybdenum dithiocarbamate of the present invention, the amount of molybdenum dithiocarbamate blended relative to the total amount of the lubricating oil composition is preferably an amount that results in an elemental molybdenum content of 10 to 3,000 ppm by mass, more preferably an amount that results in ...

When the molybdenum dithiocarbamate of the present invention is used in a lubricating oil composition, the base oil of the lubricating oil composition is not particularly limited and can be appropriately selected from mineral base oils, chemically synthesized base oils, animal and vegetable base oils, and mixed base oils thereof, etc., depending on the purpose and conditions of use.
Examples of mineral base oils include paraffinic crude oil, naphthenic crude oil, intermediate crude oil, and aromatic crude oil. Further, distillate oils obtained by atmospheric distillation of these oils, or distillate oils obtained by vacuum distillation of residual oil from atmospheric distillation, and refined oils obtained by refining these oils according to conventional methods, specifically solvent refined oil, hydrogenated refined oil, dewaxed oil, and clay-treated oil, can also be used.

Examples of chemically synthesized base oils include poly-α-olefins, polyisobutylene (polybutene), monoesters, diesters, polyol esters, silicate esters, polyalkylene glycols, polyphenyl ethers, silicones, fluorinated compounds, alkylbenzenes, and GTL base oils. Among these, examples of poly-α-olefins include polymers or oligomers of 1-hexene, 1-octene, 1-nonene, 1-decene, 1-dodecene, and 1-tetradecene, as well as hydrogenated versions of these. Examples of diesters include diesters of dibasic acids such as glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid with alcohols such as 2-ethylhexanol, octanol, decanol, dodecanol, and tridecanol. Examples of polyol esters include esters of polyols such as neopentyl glycol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, and tripentaerythritol with fatty acids such as caproic acid, caprylic acid, lauric acid, capric acid, myristic acid, palmitic acid, stearic acid, and oleic acid, and refined base oils of these can also be used.

Examples of animal and vegetable base oils include vegetable oils such as castor oil, olive oil, cocoa butter, sesame oil, rice bran oil, safflower oil, soybean oil, camellia oil, corn oil, rapeseed oil, palm oil, palm kernel oil, sunflower oil, cottonseed oil, and coconut oil, and animal oils such as beef tallow, lard, milk fat, fish oil, and whale oil. If necessary, highly refined base oils, which are obtained by highly refining these base oils to reduce the amount of impurities such as sulfur, may also be used.

The base oil used in the lubricating oil composition can be one or more of the various base oils described above. The kinematic viscosity of the base oil used in the lubricating oil composition is not particularly limited and can be adjusted appropriately depending on the purpose. For example, a base oil with a kinematic viscosity at 40°C of 1.0 to 600 cSt can be used. From the perspective of the friction characteristics and other properties of the resulting lubricating oil composition, it is preferable to use a base oil with a kinematic viscosity at 40°C of 2.0 to 200 cSt, more preferably 4.0 to 100 cSt, and even more preferably 6.0 to 50 cSt.

The lubricating oil composition containing the molybdenum dithiocarbamate of the present invention may contain known lubricating oil additives depending on the intended use, from the viewpoints of friction characteristics, wear characteristics, oxidation stability, temperature stability, storage stability, detergency, rust prevention, corrosion prevention, ease of handling, etc. Examples of such lubricating oil additives include known antioxidants, friction reducers, anti-wear agents, oiliness improvers, detergents, ashless dispersants, viscosity index improvers, rust inhibitors, corrosion inhibitors (metal deactivators), antifoaming agents, etc., and one or more of these can be used.

As the antioxidant, any antioxidant used in lubricating oils can be used without particular limitation, but examples include 2,6-di-t-butylphenol, 2,6-di-t-butyl-p-cresol, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,4-dimethyl-6-t-butylphenol, 4,4'-methylenebis(2,6-di-t-butylphenol), 4,4'-bis(2,6-di-t-butylphenol), 4,4'-bis(2-methyl-6-t-butylphenol), 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 4, 4'-isopropylidenebis(2,6-di-t-butylphenol), 2,2'-methylenebis(4-methyl-6-cyclohexylphenol), 2,2'-methylenebis(4-methyl-6-nonylphenol), 2,2'-isobutylidenebis(4,6-dimethylphenol), 2,6-bis(2'-hydroxy-3'-t-butyl-5'-methylbenzyl)-4-methylphenol, 3-t-butyl-4-hydroxyanisole, 2-t-butyl-4-hydroxyanisole, octyl 3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, stearyl 3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, oleyl 3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, dodecyl 3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, decyl 3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, tetrakis{3-(4-hydroxy-3,5-di-t-butylphenyl)propionyloxymethyl}methane, glycerin monoester of 3-(4-hydroxy-3,5-di-t-butylphenyl)propionic acid, ester of 3-(4-hydroxy-3,5-di-t-butylphenyl)propionic acid and glycerin monooleyl ether, butylene glycol diester of 3-(4-hydroxy-3,5-di-t-butylphenyl)propionic acid, thiodiglycol diester of 3-(4-hydroxy-3,5-di-t-butylphenyl)propionic acid, 4,4'-thiobis(3-methyl-6-t-butylphenyl)propionic acid phenol), 4,4'-thiobis(2-methyl-6-t-butylphenol), 2,2'-thiobis(4-methyl-6-t-butylphenol), 2,6-di-t-butyl-α-dimethylamino-p-cresol, 2,6-di-t-butyl-4-(N,N'-dimethylaminomethylphenol), bis(3,5-di-t-butyl-4-hydroxybenzyl)sulfide, tris{(3,5-di-t-butyl-4-hydroxyphenyl)propionyl-oxyethyl}isocyanurate, tris(3,5-di-t-butyl-4-hydroxyphenyl)isocyanurate, 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, bis{2-methyl-4-(3-n-alkylthiopropionyloxy)-5-t-butylfuran phenyl} sulfide, 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, tetraphthaloyl-di(2,6-dimethyl-4-t-butyl-3-hydroxybenzyl sulfide), 6-(4-hydroxy-3,5-di-t-butylanilino)-2,4-bis(octylthio)-1,3,5-triazine, 2,2-thio-{diethyl-bis-3-(3,5-di-t-butyl-4-hydroxyphenyl)}propionate, N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinamide), 3,5-di-t-butyl-4-hydroxy-benzyl-phosphate diester, bis(3-methyl-4-hydroxy-5-t-butylbenzyl) sulfide, 3,9-bis[1,1- phenolic antioxidants such as dimethyl-2-{β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane, 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, and bis{3,3'-bis-(4'-hydroxy-3'-t-butylphenyl)butyric acid}glycol ester; 1-naphthylamine, phenyl-1-naphthylamine, p-octylphenyl-1-naphthylamine, p-nonylphenyl-1-naphthylamine, p-dodecylphenyl-1-naphthylamine, phenyl-2-naphthylamine; naphthylamine-based antioxidants such as N,N'-diisopropyl-p-phenylenediamine, N,N'-diisobutyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N,N'-di-β-naphthyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine, dioctyl-p-phenylenediamine, phenylhexyl-p-phenylenediamine, and phenyloctyl-p-phenylenediamine; phenylenediamine-based antioxidants such as dipyridylamine, diphenylamine, p,p'-di-n-butyldiphenylamine, and p,p'-di-t-butyldiphenylamine; diphenylamine-based antioxidants such as phenylamine, p,p'-di-t-pentyldiphenylamine, p,p'-dioctyldiphenylamine, p,p'-dinonyldiphenylamine, p,p'-didecyldiphenylamine, p,p'-didodecyldiphenylamine, p,p'-distyryldiphenylamine, p,p'-dimethoxydiphenylamine, 4,4'-bis(4-α,α-dimethylbenzoyl)diphenylamine, p-isopropoxydiphenylamine, and dipyridylamine; and phenothiazine-based antioxidants such as phenothiazine, N-methylphenothiazine, N-ethylphenothiazine, 3,7-dioctylphenothiazine, phenothiazine carboxylic acid ester, and phenoselenazine, and these may be contained alone or in combination. The amount of these antioxidants added is not particularly limited, but is preferably 0.01 to 5 mass% of the total amount of the lubricating oil composition, and more preferably 0.02 to 4 mass%.

The friction reducer can be any friction reducer used in lubricating oils, without any particular restrictions. Examples include organic molybdenum compounds such as molybdenum dithiophosphate and molybdenum amine salts; ashless friction modifiers such as aliphatic amines, fatty acid esters, fatty acid amides, fatty acids, fatty alcohols, and aliphatic ethers, each having at least one alkyl or alkenyl group having 6 to 30 carbon atoms in the molecule; and oils, amines, amides, and sulfurized esters. One or more of these may be contained. The amount of these friction reducers to be added is not particularly limited, but is preferably 0.01 to 10 mass %, and more preferably 0.02 to 5 mass %, of the total amount of the lubricating oil composition.

As anti-wear agents, any anti-wear agent used in lubricating oils can be used without particular limitation, but examples include sulfurized fats and oils, olefin polysulfides, sulfurized olefins, dibenzyl sulfide, ethyl-3-[[bis(1-methylethoxy)phosphinothioyl]thio]propionate, tris-[(2, or 4)-isoalkylphenol]thiophosphate, 3-(di-isobutoxy-thiophosphorylsulfanyl)-2-methyl-propionic acid, triphenylphosphorothionate, β-dithiophosphorylated propionic acid, methylenebis(dibutyldithiocarbamate), O,O-diisopropyl-dithiophosphorylethylpropionate, and the like. sulfur-based additives such as 2,5-bis(n-nonyldithio)-1,3,4-thiadiazole, 2,5-bis(1,1,3,3-tetramethylbutanethio)1,3,4-thiadiazole, and 2,5-bis(1,1,3,3-tetramethyldithio)-1,3,4-thiadiazole; monooctyl phosphate, dioctyl phosphate, trioctyl phosphate, monobutyl phosphate, dibutyl phosphate, tributyl phosphate, monophenyl phosphate, diphenyl phosphate, triphenyl phosphate, tricresyl phosphate, monoisopropyl phenyl phosphate, diisopropyl phenyl phosphate, phosphate, triisopropylphenyl phosphate, mono-tert-butylphenyl phosphate, di-tert-butylphenyl phosphate, tri-tert-butylphenyl phosphate, triphenylthiophosphate, monooctyl phosphite, dioctyl phosphite, trioctyl phosphite, monobutyl phosphite, dibutyl phosphite, tributyl phosphite, monophenyl phosphite, diphenyl phosphite, triphenyl phosphite, monoisopropylphenyl phosphite, diisopropylphenyl phosphite, triisopropylphenyl phosphite, mono Examples of suitable antiwear agents include phosphorus compounds such as mono-tert-butylphenyl phosphite, di-tert-butylphenyl phosphite, and tri-tert-butylphenyl phosphite; organometallic compounds such as metal dithiophosphates (e.g., Sb, Mo), metal dithiocarbamates (e.g., Zn, Sb, W), metal naphthenates, metal fatty acid salts, metal phosphates, metal phosphate esters, and metal phosphites; and boron compounds, alkylamine salts of mono- and dihexyl phosphates, amine phosphate esters, and mixtures of triphenylthiophosphates and tert-butylphenyl derivatives. The lubricating oil composition may contain one or more of these antiwear agents. The amount of these antiwear agents to be added is not particularly limited, but is preferably 0.01 to 5 mass %, and more preferably 0.02 to 3 mass %, of the total amount of the lubricating oil composition.

The oiliness improver can be any oiliness improver used in lubricating oils, without any particular restrictions. Examples include higher alcohols such as oleyl alcohol and stearyl alcohol; fatty acids such as oleic acid and stearic acid; esters such as oleyl glycerin ester, stearyl glycerin ester, and lauryl glycerin ester; amides such as laurylamide, oleylamide, and stearylamide; amines such as laurylamine, oleylamine, and stearylamine; and ethers such as lauryl glycerin ether and oleyl glycerin ether. One or more of these may be contained. The amount of these oiliness improvers to be added is not particularly limited, but is preferably 0.01 to 5 mass %, and more preferably 0.02 to 3 mass %, of the total amount of the lubricating oil composition.

Any detergent used in lubricating oils can be used without particular restrictions. Examples include basic salts and overbased salts of metals such as calcium, magnesium, and barium, such as sulfonates, phenates, salicylates, and phosphates. One or more of these can be contained. The TBN (total base number) of these compounds is not particularly limited, but a TBN of 30 to 800 mgKOH/g is preferred. The amount of detergent to be added is not particularly limited, but a range of 0.5 to 10 mass% is preferred, and 1 to 8 mass% is more preferred, based on the total amount of the lubricating oil composition. Among these, one or more detergents consisting of a basic or overbased salt of calcium and a basic or overbased salt of magnesium are preferred, and a basic or overbased salt of calcium and a basic or overbased salt of magnesium are even more preferred. In this case, the content of calcium atoms derived from the detergent in the lubricating oil composition is not particularly limited, but from the standpoint of detergency, etc., the content of calcium atoms derived from the detergent in the lubricating oil composition is preferably 100 to 3,000 ppm by mass, and more preferably 200 to 2,500 ppm by mass. Furthermore, the content of magnesium atoms derived from the detergent in the lubricating oil composition is not particularly limited, but from the standpoint of detergency, etc., the content of magnesium atoms derived from the detergent in the lubricating oil composition is preferably 50 to 2,000 ppm by mass, and more preferably 100 to 1,000 ppm by mass.

Any ashless dispersant suitable for use in lubricating oils may be used without particular limitation. Examples include nitrogen-containing compounds having at least one linear or branched alkyl or alkenyl group having 40 to 400 carbon atoms in the molecule, or derivatives thereof. Specific examples include succinimides, succinamides, succinate esters, succinate ester-amides, benzylamines, polyamines, polysuccinimides, and Mannich bases. Derivatives thereof include those obtained by reacting these nitrogen-containing compounds with boron compounds such as boric acid and borates, phosphorus compounds such as thiophosphoric acid and thiophosphates, organic acids, and hydroxypolyoxyalkylene carbonates. The lubricating oil composition may contain one or more of these compounds. The amount of these ashless dispersants to be added is not particularly limited, but is preferably 0.5 to 10 mass %, and more preferably 1 to 8 mass %, of the total amount of the lubricating oil composition.

Any viscosity index improver suitable for use in lubricating oils can be used without particular limitation. Examples include poly(C1-18) alkyl (meth)acrylate, (C1-18) alkyl acrylate/(C1-18) alkyl (meth)acrylate copolymer, diethylaminoethyl (meth)acrylate/(C1-18) alkyl (meth)acrylate copolymer, ethylene/(C1-18) alkyl (meth)acrylate copolymer, polyisobutylene, polyalkylstyrene, ethylene/propylene copolymer, styrene/maleic acid ester copolymer, and hydrogenated styrene/isoprene copolymer. One or more of these may be contained. The weight-average molecular weight is approximately 10,000 to 1,500,000. The amount of these viscosity index improvers to be used is not particularly limited, but is preferably 0.1 to 20 mass %, and more preferably 0.3 to 15 mass %, of the total amount of the lubricating oil composition.

The rust inhibitor can be any rust inhibitor used in lubricating oils, without particular limitation. Examples include sodium nitrite, oxidized paraffin wax calcium salt, oxidized paraffin wax magnesium salt, tallow fatty acid alkali metal salt, alkaline earth metal salt or amine salt, alkenyl succinic acid or alkenyl succinic acid half ester (alkenyl group molecular weight approximately 100 to 300), sorbitan monoester, nonylphenol ethoxylate, lanolin fatty acid calcium salt, etc., and the lubricating oil composition can contain one or more of these. The amount of these rust inhibitors to be added is not particularly limited, but is preferably 0.01 to 3 mass %, and more preferably 0.02 to 2 mass %, of the total amount of the lubricating oil composition.

As the corrosion inhibitor, any corrosion inhibitor used in lubricating oils can be used without any particular limitation. Examples include triazole, tolyltriazole, benzotriazole, benzimidazole, benzothiazole, benzothiadiazole, and derivatives of these compounds, such as 2-hydroxy-N-(1H-1,2,4-triazol-3-yl)benzamide, N,N-bis(2-ethylhexyl)-[(1,2,4-triazol-1-yl)methyl]amine, N,N-bis(2-ethylhexyl)-[(1,2,4-triazol-1-yl)methyl]amine, and 2,2'-[[(4 or 5 or 1)-(2-ethylhexyl)-methyl-1H-benzotriazole-1-methyl]imino]bisethanol, bis(poly-2- Examples of the corrosion inhibitor include tetramethyl-N-(4-hydroxybenzoyl)-N' ...

The antifoaming agent can be any antifoaming agent used in lubricating oils, without particular limitation. Examples include polydimethyl silicone, dimethyl silicone oil, trifluoropropylmethyl silicone, colloidal silica, polyalkyl acrylate, polyalkyl methacrylate, alcohol ethoxy/propoxylate, fatty acid ethoxy/propoxylate, and sorbitan partial fatty acid ester, and the composition can contain one or more of these. The amount of these antifoaming agents to be added is not particularly limited, but is preferably 0.0001 to 0.1 mass%, and more preferably 0.001 to 0.01 mass%, of the total amount of the lubricating oil composition.

D. Grease Composition When the molybdenum dithiocarbamate of the present invention is added to a base oil to be used as a grease composition, the amount of molybdenum dithiocarbamate blended is not particularly limited, but from the viewpoint of making it easier to exhibit the properties of the molybdenum dithiocarbamate of the present invention, the amount of molybdenum dithiocarbamate blended relative to the total amount of the grease composition is preferably an amount that results in an elemental molybdenum content of 0.01 to 1 mass%, more preferably an amount that results in an amount that results in an amount that results in an elemental molybdenum content of 0.02 to 0.7 mass%, and even more preferably an amount that results in an amount that results in an elemental molybdenum content of 0.03 to 0.5 mass%.

When the molybdenum dithiocarbamate of the present invention is added to a base oil to form a grease composition, known grease additives may be used in combination, if necessary. Examples of grease additives include antioxidants such as amine-based antioxidants, phenol-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants; detergents such as basic salts and overbased salts of metals such as calcium, magnesium, and barium, such as sulfonates, phenates, salicylates, and phosphates; oiliness improvers such as higher alcohols, higher fatty acids, higher fatty acid glycerol esters, higher fatty acid amides, and higher alkylamines; dispersants such as alkenyl succinimides; extreme pressure agents such as phosphate esters, zinc dialkyldithiophosphates, and zinc dialkyldithiocarbamates; other organic molybdenum compounds such as dialkyldithiophosphates, molybdenum long-chain amine salts, and molybdenum alkenyl succinimide complexes; viscosity index improvers, pour point depressants, rust inhibitors, corrosion inhibitors, and antifoaming agents. These additives may also be mixed with the molybdenum dithiocarbamate of the present invention before being incorporated into the grease.

When the molybdenum dithiocarbamate of the present invention is used in a grease composition, there are no particular restrictions on the base oil of the grease composition; for example, the base oils exemplified for lubricating oil compositions can be used. Among these, the base oil used in the grease composition preferably contains at least a mineral oil or a hydrocarbon-based synthetic oil, as these are more likely to exhibit the lubrication-enhancing effect of the molybdenum dithiocarbamate. It is even more preferable to use a base oil containing a paraffin-based highly refined mineral oil, a poly-α-olefin-based or GTL-based chemically synthetic base oil, or a mixed base oil of these. In this case, it is preferable to contain 50 mass% or more of these base oils out of the total amount of base oil, as this allows the properties of the molybdenum dithiocarbamate to be more fully exhibited, and it is even more preferable for these base oils to account for 90 mass% or more of the total amount of base oil.

When the molybdenum dithiocarbamate of the present invention is added to a base oil to form a grease composition, it may further contain a thickener. Examples of thickeners include soap-based or complex soap-based thickeners, organic non-soap-based thickeners, and inorganic non-soap-based thickeners, and the grease may contain one or more of these.

Soap-based thickeners include, for example, soaps made by reacting higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, 12-hydroxystearic acid, arachic acid, behenic acid, zomalic acid, oleic acid, linoleic acid, linolenic acid, and ricinoleic acid with bases such as lithium, sodium, potassium, aluminum, barium, and calcium, as well as complex soap thickeners made by further reacting the above fatty acids and bases with acetic acid, benzoic acid, sebacic acid, azelaic acid, phosphoric acid, boric acid, etc.

Organic non-soap thickeners include, for example, terephthalate-based thickeners, urea-based thickeners, and fluorine-based thickeners such as polytetrafluoroethylene and fluorinated ethylene-propylene copolymers, with urea-based thickeners being preferred. Examples of urea-based thickeners include monourea compounds formed by reacting a monoisocyanate with a monoamine, diurea compounds formed by reacting a diisocyanate with a monoamine, ureaurethane compounds formed by reacting a diisocyanate with a monoamine and a monool, and tetraurea compounds formed by reacting a diisocyanate with a diamine and a monoisocyanate.

Examples of inorganic non-soap thickeners include carbon black, boron nitride, organic clay, silica gel, etc.

This disclosure includes the following aspects:

[1] A method for producing molybdenum dithiocarbamate, comprising: a DTC conversion step in which one or more molybdenum compounds selected from the group consisting of molybdic acid and its salts, a sulfur source including octasulfur and carbon disulfide, and an amine compound represented by general formula (1) are reacted to obtain a DTC conversion intermediate; and a reduction step in which the obtained DTC conversion intermediate is reduced in the presence of a reducing agent to obtain a molybdenum dithiocarbamate represented by general formula (2).

[2] The method for producing molybdenum dithiocarbamate according to [1], wherein the ratio of oxygen atoms to sulfur atoms (O:S) of X ¹ to X ⁴ in general formula (2) is 1.8-0:2.2-4.

[3] The method for producing molybdenum ^{dithiocarbamate} according to [1] or [2], wherein the DTC step is carried out in the presence of an organic solvent that is a monohydric alcohol having 3 to 8 carbon atoms, and in which the Hansen solubility parameters have a dispersion parameter δd value of 15.0 to 17.5 (MPa) ^1/2 , a dipolar parameter δp value of 0 to 6.8 (MPa) ^1/2 , and a hydrogen bond parameter δh of 10.0 to 17.5 (MPa) 1/2 .

[4] A method for producing molybdenum dithiocarbamate according to any one of [1] to [3], wherein the mass ratio of the sulfur element content of the octasulfur to the sulfur element content of the carbon disulfide is 10:90 to 90:10.

[5] A method for producing molybdenum dithiocarbamate according to any one of [1] to [4], wherein the reducing agent is one or more selected from the group consisting of sodium hydrosulfide, potassium hydrosulfide, sodium pyrosulfite, and sodium thiosulfate.

[6] A method for producing molybdenum dithiocarbamate according to any one of [1] to [5], wherein the molar equivalent ratio (Mo:S:amine) of the Mo element contained in the molybdenum compound, the S element contained in the sulfur source, and the amine compound is 1:1.5-10:0.8-2, where the molar equivalent of the Mo element is 1.

[7] Molybdenum dithiocarbamate obtained by the manufacturing method described in any one of [1] to [6].

[8] A lubricating oil composition or grease composition containing the molybdenum dithiocarbamate described in [7].

The present invention will be explained in more detail below with reference to the following examples. Note that in the following examples, percentages are by weight unless otherwise specified.

Example 1
A flask equipped with a stirrer, thermometer, nitrogen tube, and reflux condenser was charged with 45.2 g (0.31 mol) of molybdenum trioxide, 20.1 g (0.078 mol) of octasulfur, 39.8 g (0.16 mol) of di-2-ethylhexylamine, 62.7 g (0.16 mol) of di-isotridecylamine, 16.4 g (0.22 mol) of 1-butanol, and 4.43 g (0.02 mol) of 35% sulfuric acid. 29.5 g (0.39 mol) of carbon disulfide was then added dropwise over 1 hour at 20 to 55°C to react the raw materials, yielding a green Mo-DTC intermediate. In this DTC conversion step, the molar equivalent ratio (Mo:S:amine) of the Mo element contained in the molybdenum compound, the S element contained in the sulfur compound, and the amine compound was 1:4.4:1.05, where the molar equivalent of Mo was taken as 1. Subsequently, 100.0 g (0.53 mol) of a 30% aqueous solution of sodium hydrosulfide was added, and the mixture was reduced for 3 hours at 95° C. Thereafter, the aqueous layer was removed, the mixture was washed with water, and the mixture was dehydrated under reduced pressure. Then, 293.7 g of mineral oil (naphthenic mineral base oil, kinematic viscosity at 100° C. 2.2 mm/s) was added, and the mixture was filtered to obtain 454.8 g of an amber viscous liquid product composed of mineral oil and a molybdenum compound. The resulting viscous liquid product was analyzed using high-performance liquid chromatography, inductively coupled plasma mass spectrometry, nuclear magnetic resonance spectroscopy, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. As a result, it was found that the resulting viscous liquid product contained 157.6 g (yield 94.6%) of molybdenum dithiocarbamate represented by general formula (2), in which R ³ to R ⁶ were isotridecyl groups or 2-ethylhexyl groups (the ratio of isotridecyl groups to 2-ethylhexyl groups was 2:2), and the ratio of oxygen atoms to sulfur atoms in X ¹ to X ⁴ was 1.6:2.4.

Example 2
A flask equipped with a stirrer, thermometer, nitrogen tube, and reflux condenser was charged with 45.0 g (0.31 mol) of molybdenum trioxide, 20.3 g (0.079 mol) of octasulfur, 39.7 g (0.16 mol) of di-2-ethylhexylamine, 63.1 g (0.17 mol) of di-isotridecylamine, 17.2 g (0.23 mol) of 1-butanol, and 4.41 g (0.02 mol) of 35% sulfuric acid. 29.2 g (0.38 mol) of carbon disulfide was then added dropwise over 1 hour at 20 to 55°C to react the raw materials, yielding a green Mo-DTC intermediate. In this DTC conversion step, the molar equivalent ratio (Mo:S:amine) of the Mo element contained in the molybdenum compound, the S element contained in the sulfur compound, and the amine compound was 1:4.4:1.05, where the molar equivalent of Mo was taken as 1. Subsequently, 147.5 g (0.79 mol) of a 30% aqueous solution of sodium hydrosulfide was added, and the mixture was reduced for 3 hours at 95° C. Thereafter, the aqueous layer was removed, the mixture was washed with water, and the mixture was dehydrated under reduced pressure. Then, 297.0 g of mineral oil (naphthenic mineral base oil, kinematic viscosity at 100° C. 2.2 mm/s) was added, and the mixture was filtered to obtain 446.9 g of an amber viscous liquid product composed of mineral oil and a molybdenum compound. The resulting viscous liquid product was analyzed using high-performance liquid chromatography, inductively coupled plasma mass spectrometry, nuclear magnetic resonance spectroscopy, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. As a result, it was found that the resulting viscous liquid product contained 131.3 g (yield: 79.1%) of molybdenum dithiocarbamate represented by general formula (2), in which R ³ to R ⁶ were isotridecyl groups or 2-ethylhexyl groups (the ratio of isotridecyl groups to 2-ethylhexyl groups was 2:2) and the ratio of oxygen atoms to sulfur atoms in X ¹ to X ⁴ was 1.6:2.4.

Example 3
A flask equipped with a stirrer, thermometer, nitrogen tube, and reflux condenser was charged with 45.0 g (0.31 mol) of molybdenum trioxide, 10.1 g (0.039 mol) of octasulfur, 39.7 g (0.16 mol) of di-2-ethylhexylamine, 63.1 g (0.17 mol) of di-isotridecylamine, 17.0 g (0.23 mol) of 1-butanol, and 4.42 g (0.02 mol) of 35% sulfuric acid. The raw materials were reacted by adding 53.0 g (0.70 mol) of carbon disulfide dropwise over 1 hour at 20 to 55°C, yielding a green Mo-DTC intermediate. In this DTC conversion step, the molar equivalent ratio (Mo:S:amine) of the Mo element contained in the molybdenum compound, the S element contained in the sulfur compound, and the amine compound was 1:5.4:1.05, where the molar equivalent of Mo was 1. Subsequently, 101.7 g (0.54 mol) of a 30% aqueous solution of sodium hydrosulfide was added, and the mixture was reduced for 3 hours at 95° C. Thereafter, the aqueous layer was removed, the mixture was washed with water, and the mixture was dehydrated under reduced pressure. Then, 296.4 g of mineral oil (naphthenic mineral base oil, kinematic viscosity at 100° C. 2.2 mm/s) was added, and the mixture was filtered to obtain 446.9 g of an amber viscous liquid product composed of mineral oil and a molybdenum compound. The resulting viscous liquid product was analyzed using high-performance liquid chromatography, inductively coupled plasma mass spectrometry, nuclear magnetic resonance spectroscopy, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. As a result, it was found that the resulting viscous liquid product contained 152.3 g (yield 91.8%) of molybdenum dithiocarbamate represented by general formula (2), in which R ³ to R ⁶ were isotridecyl groups or 2-ethylhexyl groups (the ratio of isotridecyl groups to 2-ethylhexyl groups was 2:2), and the ratio of oxygen atoms to sulfur atoms in X ¹ to X ⁴ was 1.8:2.2.

<Comparative Example 1>
A flask equipped with a stirrer, thermometer, nitrogen tube, and reflux condenser was charged with 45.0 g (0.31 mol) of molybdenum trioxide, 39.6 g (0.16 mol) of di-2-ethylhexylamine, 62.8 g (0.16 mol) of di-isotridecylamine, 16.5 g (0.22 mol) of 1-butanol, and 4.56 g (0.02 mol) of 35% sulfuric acid, and 28.8 g (0.38 mol) of carbon disulfide was added dropwise over 1 hour at 20 to 55°C to react the raw materials, thereby obtaining a DTC intermediate. In this DTC conversion step, the molar equivalent ratio (Mo:S:amine) of the Mo element contained in the molybdenum compound, the S element contained in the sulfur compound, and the amine compound was 1:2.4:1.05, where the molar equivalent of Mo element was taken as 1. Subsequently, 100.8 g (0.54 mol) of a 30% aqueous solution of sodium hydrosulfide was added, followed by reduction for 3 hours at 95° C. Thereafter, the aqueous layer was removed, the mixture was washed with water, and dehydrated under reduced pressure. After that, 296.2 g of mineral oil (naphthenic mineral base oil, kinematic viscosity at 100° C. 2.2 mm/s) was added, and the mixture was filtered to obtain 411.8 g of an amber viscous liquid product composed of mineral oil and a molybdenum compound. The resulting viscous liquid product was analyzed by high performance liquid chromatography, inductively coupled plasma mass spectrometry, and nuclear magnetic resonance spectroscopy. As a result, it was found that the resulting viscous liquid product contained 99.2 g (yield 59.8%) of molybdenum dithiocarbamate represented by general formula (2), in which R ³ to R ⁶ were isotridecyl groups or 2-ethylhexyl groups (the ratio of isotridecyl groups to 2-ethylhexyl groups was 2:2), and the ratio of oxygen atoms to sulfur atoms in X ¹ to X ⁴ was 1.8:2.2.

<Comparative Example 2>
A flask equipped with a stirrer, thermometer, nitrogen tube, and reflux condenser was charged with 45.1 g (0.31 mol) of molybdenum trioxide, 39.7 g (0.16 mol) of di-2-ethylhexylamine, 62.7 g (0.16 mol) of di-isotridecylamine, 17.0 g (0.23 mol) of 1-butanol, and 4.42 g (0.02 mol) of 35% sulfuric acid, and 76.8 g (1.01 mol) of carbon disulfide was added dropwise over 1 hour at 20 to 55°C to react the raw materials, thereby obtaining a DTC intermediate. In this DTC conversion step, the molar equivalent ratio (Mo:S:amine) of the Mo element contained in the molybdenum compound, the S element contained in the sulfur compound, and the amine compound used was 1:6.4:1.05, where the molar equivalent of Mo element was taken as 1. Subsequently, the mixture was reacted at 95°C for 3 hours, the aqueous layer was removed, washed with water, and dehydrated under reduced pressure. 297.6 g of mineral oil (naphthenic mineral base oil, kinematic viscosity at 100°C 2.2 mm/s) was added, and the mixture was filtered to obtain 447.9 g of a reddish-purple viscous liquid product consisting of mineral oil and a molybdenum compound. The resulting viscous liquid product was analyzed using high-performance liquid chromatography, inductively coupled plasma mass spectrometry, and nuclear magnetic resonance spectroscopy, and the presence of the molybdenum dithiocarbamate represented by general formula (2) was not confirmed in the resulting viscous liquid product.

As the above results show, the present invention enables the production of high-sulfur molybdenum dithiocarbamate in high yield. On the other hand, in Comparative Examples 1 and 2, in which a raw material containing no octasulfur was used as the sulfur source, the yield of molybdenum dithiocarbamate was low, or molybdenum dithiocarbamate could not be produced. In these Comparative Examples, it is believed that because sufficient DTC intermediates such as those represented by general formulas (3) to (5) could not be obtained in the DTC conversion step, the desired molybdenum dithiocarbamate represented by general formula (2) could not be obtained in the subsequent reduction step. Furthermore, the high-sulfur molybdenum dithiocarbamate obtained in high yield by the present invention is expected to have excellent properties and can therefore be suitably used in lubricating oil and grease compositions.

Claims (8)

A method for producing molybdenum dithiocarbamate, comprising: a DTC conversion step of reacting one or more molybdenum compounds selected from the group consisting of molybdic acid and its salts, a sulfur source including octasulfur and carbon disulfide, and an amine compound represented by the following general formula (1) to obtain a DTC conversion intermediate; and a reduction step of reducing the obtained DTC conversion intermediate in the presence of a reducing agent to obtain a molybdenum dithiocarbamate represented by the following general formula (2).
(In the formula, R ¹ and R ² each independently represent a hydrocarbon group having 4 to 14 carbon atoms.)
(wherein R ³ to R ⁶ each independently represent a hydrocarbon group having 4 to 14 carbon atoms, and X ¹ to X ⁴ each independently represent an oxygen atom or a sulfur atom.) 2. The method for producing molybdenum dithiocarbamate according to claim 1, wherein the ratio of oxygen atoms to sulfur atoms (O:S) of X ¹ to X ⁴ in general formula (2) is 1.8-0:2.2-4. 2. The method for producing molybdenum dithiocarbamate according to claim 1, wherein the DTC step is carried out in the presence of an organic solvent which is a monohydric alcohol having 3 to 8 carbon atoms and ^which has a Hansen solubility parameter dispersion parameter δd of 15.0 to 17.5 (MPa) ^1/2 , a dipolar parameter δp of 0 to 6.8 (MPa) ^1/2 , and a hydrogen bond parameter δh of 10.0 to 17.5 (MPa) 1/2 . The method for producing molybdenum dithiocarbamate according to claim 1, wherein the mass ratio of the elemental sulfur content of the octasulfur to the elemental sulfur content of the carbon disulfide is 10:90 to 90:10. The method for producing molybdenum dithiocarbamate according to claim 1, wherein the reducing agent is one or more selected from the group consisting of sodium hydrosulfide, potassium hydrosulfide, sodium pyrosulfite, and sodium thiosulfate. The method for producing molybdenum dithiocarbamate according to claim 1, wherein the molar equivalent ratio (Mo:S:amine) of the Mo element contained in the molybdenum compound, the S element contained in the sulfur source, and the amine compound is 1:1.5-10:0.8-2, where the molar equivalent of the Mo element is 1. Molybdenum dithiocarbamate obtained by the manufacturing method described in any one of claims 1 to 6. A lubricating oil composition or grease composition containing the molybdenum dithiocarbamate of claim 7.