JP6797033B2 - Urea grease composition - Google Patents

Description

The present invention relates to a urea-based grease composition.

It is generally known that urea-based grease is excellent in heat resistance and oxidative stability. From the viewpoint of high temperature durability, urea grease is widely used in industrial machine parts such as constant velocity joints, various bearings, linear guides, and gears.
In recent years, with the achievement of both miniaturization and high output of machines and devices, grease tends to be used under a higher load or a higher temperature than before, and the environment in which grease is used has become harsher. Therefore, it is desired to enclose urea-based grease having excellent heat resistance in the parts of machines and devices. In particular, grease used in the lubrication environment of spindle bearings for wind power generation, speed reducers for wind power generation, reduction gears for industrial robots, etc. is subject to high pressure and a large load, so load bearing performance is strongly required. There is.

Conventionally, it has been known to blend a solid lubricant such as graphite, molybdenum disulfide, or an organic molybdenum compound in order to impart load-bearing performance to grease (see, for example, Non-Patent Document 1).
Further, a grease composition for gear lubrication having excellent wear resistance, which uses lithium soap as a thickener and is added with molybdenum dithiocarbamate and calcium sulfonate, is disclosed (see, for example, Patent Document 1).
Further, it contains a base oil and a thickener as a grease composition having excellent wear resistance and extreme pressure resistance and having a long life even when used in a geared motor or the like, and as an extreme pressure agent, 0 in terms of sulfur content. At least one of 0.01% by mass to 1% by mass (based on the total amount of the composition) and zinc dithiocarbamate, and a phosphorus-based extreme pressure of 150% by mass to 4000% by mass (based on the total amount of the composition) in terms of phosphorus amount. A grease composition containing an agent is disclosed (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2004-269722 Japanese Unexamined Patent Publication No. 2008-143927

Japan Tribology Society Grease Study Group ed .: "Basics and Applications of Lubricating Grease", Yokendo, 2007, p. 77

However, in reality, even if extreme pressure type grease is used, the sufficient lubrication function is not always exhibited, and the metal parts of machines and devices may reach the end of their life earlier than expected.
In order to improve the life of metal parts, a technique for preventing seizure under a high load and suppressing metal wear is required.
The grease compositions described in Patent Documents 1 and 2 may not have sufficient wear resistance under a load capacity. Further, the grease composition using lithium soap described in Patent Document 1 does not have sufficient heat resistance. Furthermore, urea-based greases that use urea compounds as thickeners for heat-resistant greases contain additives such as extreme pressure agents and anti-wear agents, as compared to metal soap-based greases that use metal soaps as thickeners. It is known that it is difficult to obtain the effect of the additive when blended.

The present invention has been made in view of the above, and an object of the present invention is to provide a urea-based grease composition having heat resistance and excellent load-bearing performance and wear-resistant performance.

As a result of diligent studies to solve the above problems, the present inventors have identified a specific amount of sulfur-based extreme pressure agent containing an aliphatic diurea compound as a thickener and having a specific structure in the grease composition. It has been found that the grease composition has heat resistance and the load-bearing performance and the wear-resistant performance are improved by adding at least one kind of a phosphorus-based wear inhibitor having a specific amount.

Means for solving the above problems include the following embodiments.
<1> A base oil, a linear or branched aliphatic diurea compound as a thickener, and at least one sulfur-based extreme pressure agent selected from the group consisting of polysulfide, sulfide olefin, sulfide ester, and sulfide fat and oil. Select from 0.1% by mass to 2% by mass in terms of sulfur content with respect to the total mass of the grease composition, and amine salts of acidic phosphoric acid esters having 1 to 6 carbon atoms and acidic phosphoric acid esters having 1 to 6 carbon atoms. A urea-based grease composition containing at least one phosphorus-based anti-wear agent, which is 0.1% by mass to 1% by mass in terms of phosphorus amount, based on the total mass of the grease composition.

<2> The sulfur-based extreme pressure agent is at least one of polysulfide and sulfide oil and fat, and the phosphorus-based wear inhibitor is an acidic phosphoric acid ester having 1 to 4 carbon atoms and an acidic phosphoric acid ester having 1 to 4 carbon atoms. The urea-based grease composition according to <1>, which is at least one selected from the amine salts of.

According to the present invention, there is provided a urea-based grease composition having heat resistance and excellent load-bearing performance and wear-resistant performance.

Hereinafter, embodiments for carrying out the present invention will be described in detail.
In addition, in this specification, "~" which represents a numerical range represents the range including the numerical value described as the upper limit and the lower limit respectively. Further, when the unit is described only for the upper limit value in the numerical range represented by "~", it means that the lower limit value is also the same unit.
In the present specification, the content of each component in the composition is the total of the plurality of substances present in the composition unless otherwise specified, when a plurality of substances corresponding to each component are present in the composition. Means the content rate of.

<Urea grease composition>
The urea-based grease composition of the present invention (hereinafter, also referred to as "grease composition") includes a base oil, a linear or branched aliphatic diurea compound as a thickener, polysulfide, an olefin sulfide, and a sulfide ester. At least one sulfur-based extreme pressure agent (hereinafter, also referred to as “specific sulfur-based extreme pressure agent”) selected from the group consisting of sulfide oils and fats is 0.1 in terms of sulfur amount with respect to the total mass of the grease composition. At least one phosphorus-based anti-wear agent selected from an amine salt of an acidic phosphoric acid ester having 1 to 6 carbon atoms and an acidic phosphoric acid ester having 1 to 6 carbon atoms (hereinafter, "specific phosphorus") having a mass% to 2% by mass. (Also referred to as “system wear inhibitor”) is contained in an amount of 0.1% by mass to 1% by mass in terms of phosphorus amount with respect to the total mass of the grease composition. The grease composition may contain other components in addition to the above components.

The grease composition of the present invention has the above-mentioned structure, and although it is a grease composition containing an aliphatic diurea compound having a linear or branched chain as a thickener, it has heat resistance and an excellent load capacity. It is possible to exhibit performance and wear resistance. The reason for this is not clear, but it is presumed as follows.
It is presumed that the urea compound, which is a thickener, is more easily adsorbed on the metal surface than additives such as extreme pressure agents and anti-wear agents, and inhibits the adsorption of the additive on the metal surface. Therefore, in urea-based grease containing a urea compound, the effect of the additive tends to be difficult to be sufficiently exhibited.
Sulfur, phosphorus, etc. contained in the specific sulfur-based extreme pressure agent and the specific phosphorus-based anti-wear agent used in the grease composition of the present invention have higher adsorptivity to the metal surface than the urea compound, so that the additive is added to the metal surface. It is presumed that the film (lubricating film) is preferentially formed. Since the formed lubricating film is relatively soft and tends to be easily sheared, it is possible to prevent friction and wear between the metals.
Further, since the contact surface under a high load is in a high temperature state, the sulfur-based extreme pressure agent containing sulfur or phosphorus and the phosphorus-based wear inhibitor, which exhibit high activity under high temperature, are applied to the metal surface of the machine or device. It is more responsive and tends to promote the formation of a lubricating film.
Further, since the grease composition of the present invention contains a specific sulfur-based extreme pressure agent and a specific phosphorus-based wear inhibitor in specific amounts, the grease composition appropriately meets the metal surface to the extent that it does not promote corrosive wear of metal parts of machines and devices. It becomes possible to react to form a lubricating film.
Since the grease composition of the present invention contains a linear or branched aliphatic diurea compound as a thickener, it has heat resistance and can exhibit excellent load resistance.
That is, even if the grease composition of the present invention contains a urea compound as a thickener, it has excellent load bearing performance and resistance without impairing the effect of adding the specific sulfur-based extreme pressure agent and the specific phosphorus-based wear inhibitor. It is presumed that it exhibits wear performance and has heat resistance.
Hereinafter, each component contained in the grease composition will be described.

(1) Base oil The grease composition of the present invention contains a base oil. The base oil is not particularly limited, and may be, for example, a mineral oil, a synthetic oil, or a mixed oil thereof. As the base oil, synthetic oil is preferable from the viewpoint of excellent lubrication long life of grease and heat resistance of the base oil.
Examples of the synthetic oil include ether-based synthetic oils such as alkyldiphenyl ethers, ester-based synthetic oils such as diesters, polyol esters and complex-type polyol esters, synthetic hydrocarbon oils such as polyα-olefins, and alkylnaphthalene-based synthetic oils.

(2) Thickener (i) Composition of Aliphatic Diurea Compound The grease composition of the present invention contains a linear or branched aliphatic diurea compound which is a thickener. When the grease composition contains a linear or branched aliphatic diurea compound, it tends to have excellent heat resistance.
Examples of the straight-chain or branched-chain aliphatic diurea compound include those obtained by reacting a straight-chain or branched-chain aliphatic monoamine with diisocyanate.
In the present specification, the linear or branched aliphatic diurea compound includes a diurea compound having at least a linear or branched aliphatic hydrocarbon group in the compound.

Examples of the straight-chain or branched-chain aliphatic monoamine include saturated or unsaturated aliphatic monoamines having 6 to 20 carbon atoms.

Examples of the linear or branched saturated aliphatic monoamine having 6 to 20 carbon atoms include octylamine, 2-ethylhexylamine, dodecylamine, dioctylamine, di (2-ethylhexyl) amine, octadecylamine and the like.

Examples of the unsaturated aliphatic monoamine having a linear or branched chain having 6 to 20 carbon atoms include oleylamine and the like.

Examples of the diisocyanate include aromatic diisocyanates, aliphatic diisocyanates and alicyclic diisocyanates.

Examples of the aromatic diisocyanate include 4,4'-diphenylmethane diisocyanate (MDI), 2,4- or 2,6-toluene diisocyanate (TDI), m- or p-phenylenediocyanate, 1,3- or 1, Examples thereof include 4-xylylene diisocyanate (XDI) and 1,5-naphthalenediocyanate (NDI).

Examples of the aliphatic diisocyanate include hexamethylene diisocyanate (HDI), hydrogenated MDI (H12MDI), and trimethylhexamethylene diisocyanate.

Examples of the alicyclic diisocyanate include hydrogenated xylylene diisocyanate and isophorone diisocyanate.

As a combination of a linear or branched aliphatic monoamine and a diisocyanate, a combination of a linear or branched saturated aliphatic monoamine having 6 to 20 carbon atoms and an aromatic diisocyanate is preferable, and a direct chain having 6 to 20 carbon atoms is used. The combination of the saturated aliphatic monoamine of the chain and the aromatic diisocyanate is more preferable, and among these, the linear saturated aliphatic monoamine having 6 to 20 carbon atoms is octylamine, and the aromatic diisocyanate is used from the viewpoint of heat resistance. , 4, 4'-Diphenylmethane diisocyanate is more preferred.

Examples of the linear or branched aliphatic diurea compound include compounds represented by the following formula (1).

In formula (1), R ¹ and R ³ independently represent a linear or branched alkyl group having 6 to 20 carbon atoms, and R ² represents a divalent hydrocarbon group having 1 to 30 carbon atoms. ..

From the viewpoint of improving heat resistance, R ¹ and R ³ are preferably a linear alkyl group having 6 to 20 carbon atoms, more preferably a linear alkyl group having 6 to 15 carbon atoms, and having 6 to 10 carbon atoms. A straight chain alkyl group is more preferred.

Examples of the linear alkyl group having 6 to 20 carbon atoms include an n-hexyl group, an n-nonyl group, an n-octyl group, an n-decyl group, an n-dodecyl group, an n-hexadecyl group and an n-octadecyl group. Can be mentioned.

From the viewpoint of improving heat resistance, R ² is more preferably a divalent hydrocarbon group having 6 to 20 carbon atoms, and further preferably a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms.

Examples of the divalent aromatic hydrocarbon group having 6 to 15 carbon atoms include a phenylene group, a methylphenylene group, a dimethylphenylene group, a naphthylene group, a diphenylmethane group, a 1,1-diphenylethane group and 1,1,1-. Examples thereof include a methyldiphenylethane group.

The method for synthesizing the linear or branched aliphatic diurea compound is not particularly limited, and a known method can be used. For example, a straight-chain or branched-chain aliphatic diurea compound can be obtained by heating and mixing a linear or branched-chain aliphatic monoamine and diisocyanate in the presence of a base oil.

(Ii) Content The content of the linear or branched aliphatic diurea compound can be appropriately adjusted according to the desired mixing consistency, and is preferably 3% by mass to 20% by mass based on the total mass of the grease composition. It is by mass, more preferably 5% by mass to 15% by mass.

(3) Additives (i) Specified Sulfur-based Extreme Pressure Agent The grease composition of the present invention contains at least one sulfur-based extreme pressure agent selected from the group consisting of polysulfide, olefin sulfide, sulfide ester and fat and oil sulfide.
It is presumed that sulfur contained in the specific sulfur-based extreme pressure agent is adsorbed on the metal surface and reacts with the metal surface to form a sulfide film having a small shearing force. When the grease composition contains at least one sulfur-based extreme pressure agent selected from the group consisting of polysulfide, sulfide olefin, sulfide ester and sulfide oil and fat, a sulfide film is formed and wear of metal parts of machines and equipment. And tend to prevent fusion. Further, by combining the specific phosphorus-based wear inhibitor described later and the specific sulfur-based extreme pressure agent, it is possible to further improve the load bearing performance.

From the viewpoint of load bearing performance and wear resistance, the specific sulfur-based extreme pressure agent is preferably at least one selected from the group consisting of polysulfide, olefin sulfide and fat and oil sulfide, and at least one of polysulfide and fat and oil sulfide. More preferably, and even more preferably polysulfide.

Examples of polysulfide include diisobutyldisulfide, dioctylpolysulfide, di-tert-butylpolysulfide, di-tert-nonylpolysulfide, di-tert-dodecyltrisulfide, and dibenzylpolysulfide.

Examples of the sulphide olefin include those obtained by sulphurizing olefins such as polyisobutylene and terpenes with a sulfide such as sulfur.

Examples of the sulfurized fats and oils include those obtained by sulfurizing animal and vegetable fats and oils such as beef tallow, lard, fish fat, rapeseed oil, and soybean oil by a known method. Specific examples of the sulfide oil and fat include lard sulfide, rapeseed sulfide oil, castor oil sulfide, soybean sulfide oil, fish sulfide oil, and whale sulfide oil.

Examples of the sulfide ester include alkyl esters having 1 to 12 carbon atoms of sulfide fatty acids having 8 to 22 carbon atoms.

Examples of the sulfide ester include unsaturated fatty acid esters obtained by reacting unsaturated fatty acids such as oleic acid, linoleic acid or fatty acids extracted from the above animal and vegetable fats and oils with various alcohols, and sulfided by an arbitrary method. ..

Specific examples of the sulfide ester include sulfide fatty acid methyl ester and the like.

The content of the specific sulfur-based extreme pressure agent is 0.1% by mass to 2% by mass in terms of sulfur amount with respect to the total mass of the grease composition. If the content of the specific sulfur-based extreme pressure agent is less than 0.1% by mass, the effect of improving the load-bearing performance is not sufficient. If the content of the specific sulfur-based extreme pressure agent exceeds 2% by mass, no effect can be expected for the content, and the thermal stability may be impaired. From the above viewpoint, the content of the specific sulfur-based extreme pressure agent is preferably 0.25% by mass to 1.8% by mass, and more preferably 0.5% by mass to 1.5% by mass.

The grease composition of the present invention may be used in combination with a sulfur-based extreme pressure agent other than the specified sulfur-based extreme pressure agent as long as the effects of the present invention are not impaired.
When the grease composition of the present invention contains a sulfur-based extreme pressure agent other than the specified sulfur-based extreme pressure agent, the content of the sulfur-based extreme pressure agent other than the specified sulfur-based extreme pressure agent is determined from the viewpoint of oxidation stability. The amount of sulfur is preferably 0.1% by mass to 0.5% by mass with respect to the total mass of the composition.

(Ii) Specific phosphorus-based wear inhibitor The grease composition of the present invention has at least one phosphorus-based wear selected from an amine salt of an acidic phosphoric acid ester having 1 to 6 carbon atoms and an acidic phosphoric acid ester having 1 to 6 carbon atoms. Contains inhibitor.
It is presumed that the specific acidic phosphoric acid ester is adsorbed on the metal surface and reacts with the metal surface to form a film (lubricating film) of an inorganic compound having a small shearing force. In particular, since the acidic phosphoric acid ester is acidic, it tends to react more easily with the metal surface and form a lubricating film as compared with the phosphoric acid ester.
When the grease composition contains an acidic phosphoric acid ester having 1 to 6 carbon atoms as a phosphorus-based wear inhibitor, a film of an inorganic compound is formed to prevent wear and fusion of metal parts of machines and devices. Is possible.
Further, by combining the specific phosphorus-based wear inhibitor and the specific sulfur-based wear inhibitor, the load-bearing performance can be further improved.

Examples of the acidic phosphoric acid ester having 1 to 6 carbon atoms include compounds represented by the following general formula (2).

In the general formula (2), R ^{3 to} R ⁵ independently represent a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms. However, of R ^{3 to} R ⁵ , one or two are hydrogen atoms, the rest are monovalent hydrocarbon groups having 1 to 6 carbon atoms, and all of R ^{3 to} R ⁵ are hydrogen atoms or hydrocarbon groups. It cannot be.

Examples of the hydrocarbon group of R ^{3 to} R ⁵ include an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group, and any of them may be used. Among these, the hydrocarbon group of R ^{3 to} R ⁵ is preferably an aliphatic hydrocarbon group.

When the hydrocarbon group in R ^{3 to} R ⁵ is an aliphatic hydrocarbon group, the aliphatic hydrocarbon group may be a linear aliphatic hydrocarbon group or a branched chain aliphatic hydrocarbon group. Good. Further, the aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group.

From the viewpoint of abrasion resistance, R ^{3 to} R ⁵ are preferably hydrogen atoms or monovalent saturated aliphatic hydrocarbon groups independently, and hydrogen atoms or monovalent linear saturated aliphatic hydrocarbon groups are more preferable. preferable.

The monovalent linear saturated aliphatic hydrocarbon group in R ^{3 to} R ⁵ has 1 to 6 carbon atoms, preferably 1 to 5 carbon atoms from the viewpoint of wear resistance, and 1 to 4 carbon atoms. More preferably, 1 carbon number is further preferable.

Examples of the compound represented by the general formula (2) include compounds having a linear aliphatic hydrocarbon group or a branched chain aliphatic hydrocarbon group.

Specific examples of the compound having a linear aliphatic hydrocarbon group include methyl acidic phosphoric acid ester, ethyl acidic phosphoric acid ester, butyl acidic phosphoric acid ester, hexylic acid phosphoric acid ester and the like.

Specific examples of the compound having a branched-chain aliphatic hydrocarbon group include isopropyl acidic phosphoric acid ester and the like.

Examples of the amine salt of the acidic phosphoric acid ester include those obtained by neutralizing the acidic phosphoric acid ester with an amine compound represented by the following general formula (3).

In the general formula (3), R ^{6 to} R ⁸ independently represent a monovalent hydrocarbon group or a hydrogen atom having 1 to 22 carbon atoms, and at least one of R ^{6 to} R ⁸ is a hydrocarbon. Indicates a group.

Examples of the hydrocarbon group of R ^{6 to} R ⁸ include an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group, and any of them may be used. Among these, the hydrocarbon group of R ^{6 to} R ⁸ is preferably an aliphatic hydrocarbon group.

When the hydrocarbon group in R ^{6 to} R ⁸ is an aliphatic hydrocarbon group, the aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group. ..

Further, the aliphatic hydrocarbon group may be a linear aliphatic hydrocarbon group or a branched chain aliphatic hydrocarbon group.

The monovalent aliphatic hydrocarbon group in R ^{6 to} R ⁸ has 1 to 22 carbon atoms, and 4 to 18 carbon atoms are preferable from the viewpoint of wear resistance.

Specific examples of the amine compound represented by the general formula (3) include dibutylamine, octylamine, dioctylamine, 2-ethylhexylamine, di (2-ethylhexyl) amine, dodecylamine, tert-dodecylamine, and laurylamine. Examples thereof include dilaurylamine, oleylamine, coconutamine and beef fat amine.

Specific examples of the amine salt of the acidic phosphoric acid ester include a di (2-ethylhexyl) amine salt of the methyl acidic phosphoric acid ester, a tert-dodecylamine salt of the methyl acidic phosphoric acid ester, and a di (2-ethylhexyl) of the butyl acidic phosphoric acid ester. Ethylhexyl) amine salt, tert-dodecylamine salt of butyl acidic phosphate and the like can be mentioned.

The content of the specific phosphorus-based anti-wear agent is 0.1% by mass to 1% by mass in terms of phosphorus amount with respect to the total mass of the grease composition. If the content of the specific phosphorus-based wear inhibitor is less than 0.1% by mass, the effect of improving the wear resistance performance is not sufficient, and if it exceeds 1% by mass, corrosion wear tends to be promoted.
From the above viewpoint, the content of the specific phosphorus-based wear inhibitor is preferably 0.1% by mass to 0.5% by mass, and more preferably 0.2% by mass to 0.4% by mass.

The grease composition of the present invention may be used in combination with a phosphorus-based abrasion inhibitor other than the specific phosphorus-based abrasion inhibitor as long as the effects of the present invention are not impaired.

When the grease composition of the present invention contains a phosphorus-based wear inhibitor other than the specific phosphorus-based wear inhibitor, the content of the phosphorus-based wear inhibitor other than the specific phosphorus-based wear inhibitor is determined from the viewpoint of suppressing metal corrosion. The amount of phosphorus is preferably 0.1% by mass to 0.2% by mass based on the total mass of the grease composition.

(4) Other Additives In the grease composition of the present invention, additives such as antioxidants, corrosion inhibitors, rust preventives and the like other than the above additives can be appropriately added as needed. Other additives may be used alone or in combination of two or more.

Antioxidants include alkylphenols such as 2,6-di-tert-butyl-p-cresol, bisphenols such as 4,4'-methylenebis- (2,6-di-t-butylphenol), and n-octadecyl. Examples thereof include phenolic compounds such as -3- (4'-hydroxy-3', 5'-di-t-butylphenol) propionates, aromatic amine compounds such as naphthylamines and dialkyldiphenylamines, and zinc thiophosphate compounds.

When the antioxidant is added, the addition ratio is preferably 0.5% by mass to 5% by mass, more preferably 1% by mass to 4% by mass, based on the total mass of the grease composition.

Examples of the corrosion inhibitor include benzotriazole, triltriazole, thiadiazole, benzimidazole and the like.

Examples of the rust preventive include a sulfonic acid metal salt compound and a sorbitan compound.

Hereinafter, the present invention will be specifically described with reference to Examples. The present invention is not limited to these examples.

(Examples 1 to 8 and Comparative Examples 1 to 11)
In Examples and Comparative Examples, the following components * 1 to * 19 were contained in the proportions of the blending amounts (parts by mass) shown in Tables 1 and 2 to prepare a grease composition. In addition, "-" in the table means that the said component is not blended.

* 1: Base oil; Mineral oil A (hydrorefined mineral oil, 40 ° C. kinematic viscosity: 32 mm ² / s)
* 2: Base oil; Mineral oil B (hydrorefined mineral oil, 40 ° C. kinematic viscosity: 99 mm ² / s)

* 3: Thickener; straight-chain or branched-chain aliphatic diurea compound <Procedure for producing straight-chain or branched-chain aliphatic diurea compound>
Mineral oil A or mineral oil B base oil and 4,4'-diphenylmethane diisocyanate are added to a heat-resistant container, heated to about 90 ° C. with stirring, and then a mixed solution of the above base oil and octylamine is prepared. In addition, the reaction was carried out for about 60 minutes. Then, the mixture was heated to 160 ° C. with stirring and then cooled to 60 ° C. to obtain a linear or branched aliphatic diurea compound.
* 4: Thickener; alicyclic diurea compound <Procedure for manufacturing alicyclic diurea compound>
Mineral oil B and 4,4'-diphenylmethane diisocyanate are added as base oils to a heat-resistant container, heated to about 90 ° C. with stirring, and then a solution of the above base oil and cyclohexylamine is added. It was allowed to react for 60 minutes. Then, the mixture was heated to 160 ° C. with stirring and then cooled to 60 ° C. to obtain an alicyclic diurea compound.

* 5: Sulfur-based extreme pressure agent; polysulfide (compound name: di-tert-dodecyltrisulfide, trade name: TPS20, manufactured by Atofina Japan Co., Ltd.)
* 6: Sulfur-based extreme pressure agent; olefin sulfide (compound name: isobutylene sulfide, trade name: ELCO217, manufactured by The Elco Corporation)
* 7: Sulfur-based extreme pressure agent; sulfide fats and oils (compound name: sulfurized lard, trade name: Mayco Base1351, manufactured by DOVER CHEMICAL CORPORATION)
* 8: Sulfur-based extreme pressure agent; sulfide ester (compound name: sulfide fatty acid methyl ester, trade name: Dylube GS-230S, manufactured by DIC Corporation)
* 9: Sulfur-based extreme pressure agent; MoDTC (Compound name: molybdenum dibutyldithiocarbamate, trade name: MOLYVAN A, manufactured by Vanderbilt Chemicals)
* 10: Sulfur-based extreme pressure agent; ZnDTP (compound name: zinc dialkyldithiophosphate, trade name: HiTEC7197, manufactured by Afton Chemical Corporation)
* 11: Sulfur-based extreme pressure agent; MoS ₂ (Compound name: molybdenum disulfide, trade name: B powder, manufactured by Daizo Co., Ltd.)
* 12: Phosphorus-based anti-wear agent; acidic phosphoric acid ester A (with 1 carbon atom. Compound name: methyl acidic phosphoric acid ester, trade name: Phoslex A-1, manufactured by SC Organic Chemical Co., Ltd.)
* 13: Phosphorus-based anti-wear agent; acidic phosphoric acid ester B (with 4 carbon atoms. Compound name: butyl acidic phosphoric acid ester, trade name: Phoslex A-4, manufactured by SC Organic Chemical Co., Ltd.)
* 14: Phosphorus-based anti-wear agent; acidic phosphoric acid ester C (having 8 carbon atoms and having a straight chain. Compound name: octyl acidic phosphoric acid ester, trade name: Phoslex A-8N, manufactured by SC Organic Chemical Co., Ltd.)
* 15: Phosphorus-based anti-wear agent; acidic phosphoric acid ester D (having a branched chain with 8 carbon atoms. Compound name: 2-ethylhexylic phosphate ester, trade name: Phoslex A-8, SC Organic Chemistry Co., Ltd. Made)
* 16: Phosphorus-based anti-wear agent; amine salt a of acidic phosphoric acid ester A (* 12 amine salt. Compound name: di (2-ethylhexyl) amine salt of methyl acidic phosphoric acid ester, trade name: Rubedyne 1500, SC organic Made by Chemical Co., Ltd.)
* 17: Phosphorus-based anti-wear agent; amine salt b of acidic phosphoric acid ester A (* 12 amine salt. Compound name: tert-dodecylamine salt of methyl acidic phosphoric acid ester, trade name: Rubedyne 3000, SC Organic Chemistry Co., Ltd. ) Made)
* 18: Phosphorus-based anti-wear agent; amine salt c of acidic phosphoric acid ester D (* 15 amine salt. Compound name: oleylamine salt of 2-ethylhexylic phosphate ester, trade name: Phospair-16, SC organic chemistry ( Made by Co., Ltd.)
* 19: Phosphorus-based anti-wear agent; Phosphate ester (Compound name: tricresylphosphate, trade name: TCP, manufactured by Daihachi Chemical Industry Co., Ltd.)

The obtained grease composition was evaluated for its mixing consistency, drip point, load-bearing performance, and seizure-preventing performance.

(Measuring method)
(1) Mixing consistency Measured based on the consistency test method of JIS K 2220: 2013.

(2) Drip point As an evaluation of heat resistance, measurement was performed based on the drip point test method of JIS K 2220: 2013. As a test condition, the expected dropping point was set to 190 ° C. If the sample did not drip even when the test temperature reached 230 ° C, the result was indicated as “> 230 ° C” at 230 ° C or higher.

(3) Load-bearing performance and wear-resistant performance A four-ball extreme pressure test was conducted based on ASTM D 2596, and the fusion load (WP; Weld Point, unit: kgf) and maximum non-seizure load (LNSL; Last Non-Seizure Road) were carried out. , Unit; kgf), and the load-bearing performance and wear-resistant performance were evaluated. As the test conditions, the rotation speed was 1770 ± 60 rpm, the time was 10 seconds, and the temperature was room temperature.

As for the fusion load (WP), the larger the value of the fusion load, the better the load bearing capacity. JIS K2220 stipulates that the fusion load (WP) in this test is 250 kgf or more as the load-bearing grease, and it is preferably more than 315 kgf, more preferably 400 kgf or more from the viewpoint of load-bearing performance. ..

The larger the value of the maximum non-seizure load (LNSL), the better the wear resistance. In this test, the maximum non-seizure load (LNSL) is preferably 160 kgf or more, and more preferably 200 kgf or more, from the viewpoint of wear resistance performance.

As shown in Table 1, a base oil, a linear or branched aliphatic diurea as a thickener, a specific amount of a specific sulfur-based extreme pressure agent, and a specific amount of a specific phosphorus-based anti-wear agent. The grease compositions of Examples 1 to 8 containing the grease compositions had higher values of the fusion load and the maximum non-seizure load as compared with Comparative Examples 1 to 11, and were excellent in load bearing performance and wear resistance performance. Further, it can be seen that the grease compositions of Examples 1 to 8 have a drip point temperature of 230 ° C. or higher and have heat resistance.
On the other hand, as shown in Table 2, Comparative Example 1 containing no specific phosphorus-based anti-wear agent, Comparative Example 4 containing an acidic phosphoric acid ester having a straight chain having 8 carbon atoms, and branching having 8 carbon atoms. The grease compositions of Comparative Example 5 containing an acidic phosphoric acid ester having a chain, Comparative Example 6 containing an amine salt of an acidic phosphoric acid ester having a branched chain having 8 carbon atoms, and Comparative Example 7 containing a phosphoric acid ester , The load resistance and wear resistance were inferior.
Comparative Example 2 not containing the specific sulfur-based extreme pressure agent, Comparative Example 3 in which the sulfur or phosphorus equivalent amount of the specific sulfur-based extreme pressure agent and the specific phosphorus-based anti-wear agent is less than 0.1% by mass, the specific sulfur-based extreme pressure The grease compositions of Comparative Example 8 containing MoDTC which is not an agent, Comparative Example 9 containing ZnDTP as a sulfur-based extreme pressure agent, and Comparative Example 11 containing an alicyclic diurea have wear resistance, but load resistance. Was inferior. The grease composition of Comparative Example 10 containing MoS ₂ , which is not a specific sulfur-based extreme pressure agent, had load-bearing performance, but was inferior in wear-resistant performance.

Based on the above, the grease composition of the present invention is a combination of a specific sulfur-based extreme pressure agent and a specific phosphorus-based anti-wear agent, and the specific sulfur-based extreme pressure agent is converted into a sulfur amount with respect to the total mass of the grease composition. By including 0.1% by mass to 2% by mass and 0.1% by mass to 1% by mass of a specific phosphorus-based anti-wear agent in terms of phosphorus amount with respect to the total mass of the grease composition. Although it is a grease compound containing a linear or branched aliphatic sulfur compound in the agent, it has heat resistance without impairing the effect of adding the additive, and exhibits excellent load bearing performance and abrasion resistance.

The grease composition of the present invention can be suitably used for various industrial machines, automobiles, etc., and in particular, it can be suitably used as grease for gear mechanisms such as speed reducers for wind power generation and speed reducers for robot machines. It is possible.

Claims (2)

Base oil and
Linear or branched aliphatic diurea compounds that are thickeners,
At least one sulfur-based extreme pressure agent selected from the group consisting of polysulfide, olefin sulfide, sulfide ester, and sulfide oil and fat was added to the total mass of the grease composition in terms of 0.1% by mass to 2% by mass in terms of sulfur amount.
At least one phosphorus-based anti-wear agent selected from an amine salt of an acidic phosphoric acid ester having 1 to 6 carbon atoms and an acidic phosphoric acid ester having 1 to 6 carbon atoms is added to the total mass of the grease composition in terms of phosphorus content. From 0.1% by mass to 1% by mass,
Urea grease composition containing. The sulfur-based extreme pressure agent is at least one of polysulfide and sulfide oil and fat, and the phosphorus-based anti-wear agent is an amine salt of an acidic phosphoric acid ester having 1 to 4 carbon atoms and an acidic phosphoric acid ester having 1 to 4 carbon atoms. The urea-based grease composition according to claim 1, which is at least one selected from.