JP2006063248A - Lubricant additive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricant additive having excellent functions as an oxidation-stable, heat-stable and NOx resistant extreme-pressure additive or atntiwear agent and a lubrication oil composition containing it. <P>SOLUTION: The lubricant additive is composed of a phosphate derivative expressed by formula [I] [wherein, Y represents S(sulfur) or O(oxygen); R<SP>1</SP>represents a 4-24C organic group; R<SP>2</SP>represents a 1-6C divalent organic group; n is an integer of 1-3]. The lubrication oil composition contains the additive. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an additive for lubricants, and more specifically, a novel phosphate ester derivative having excellent oxidation stability, thermal stability, and NOx deterioration resistance, and having an excellent function as an extreme pressure additive and an antiwear agent. The present invention also relates to a lubricant additive comprising a reaction product of the phosphate ester derivative and a zinc compound or a mixture of the phosphate ester derivative and an organic zinc compound, and a lubricating oil composition containing these additives.

The lubricating oil is required to have an ability to prevent wear of the metal surface due to sliding contact or rolling contact between the parts when the mechanical device is operated and an ability to control wear. Therefore, the role of the additive becomes extremely important in order to improve the wear resistance of the lubricating oil and extend the life of the apparatus.
On the other hand, the base oil alone cannot have many special properties required for the use of other lubricating oil compositions including internal combustion engine lubricating oil and drive system lubricating oil. Therefore, it is necessary to use the additive for lubricating oil to impart each specific property and improve the performance of the lubricating oil composition. For this reason, a search has been made for lubricating oils having one or more properties suitable for use in these lubricating oil compositions.
For example, Patent Document 1 discloses a general formula as a lubricating oil.

[Wherein, R represents a saturated aliphatic hydrocarbon group having 2 to 3 carbon atoms, X represents O or S, respectively, and a plurality of R ′ are each an alkyl group having 1 to 18 carbon atoms, or the like. The phosphorous and sulfur-containing phosphoric acid ester compounds represented by the formula are disclosed, but no specific use is described.
Patent Document 2 discloses a general formula.

[Wherein, A represents an alkylene group having 2 to 6 carbon atoms, and R ′ represents an alkyl group having 2 to 4 carbon atoms, respectively. ] The phosphoric acid ester derivative represented by this is further disclosed, and this is copolymerized with an acrylic ester and used as a flameproofing agent.
Patent Document 3 discloses an aromatic amine and a general formula.

[Wherein, X is O or S (at least one is S), m is 0 or 1 (at least three m is 1), and a plurality of R are alkyl groups or aromatic groups. An ester-based lubricating composition comprising an organic thiophosphoric acid or phosphorous acid represented by the following formula is disclosed and used as an antioxidant.
In Patent Document 4, the general formula Ya-S-Yb [wherein Ya is

Z is a hydrocarbyl group, R is a hydrocarbyl group, a hydrocarbyloxy group, etc., and R ′ is hydrogen or a divalent hydrocarbyl group. X is S or O, and Yb is a hydrocarbyl group or the like. The phosphorus and sulfur containing compounds represented by the formula are described and used as oxidation stabilizers and antiwear agents.
Patent Document 5 discloses a general formula.

[Wherein, R represents an alkyl group, a cycloalkyl group, R ′ represents an alkyl group, x is 1 to 4, m is 1 or 2, and m + m ′ = 3. ] And is used as a corrosion inhibitor for ferrous metals.
Patent Document 6 describes that the general formula RO- (CH ₂ CH ₂ O) _x P (R ′) — OH
[Wherein, R is an alkyl group or alkenyl, R ′ is OH, alkoxy or the like, and x is 2-4. ], And is used as an additive for improving water tolerance for oil.
Patent Document 7 discloses a general formula.

[Wherein, R is alkyl or the like, R ′ is an alkylene group, and X represents O, NH or S. m is 1 to 3, m ′ is 1 to 12, and m ^″ is 0 or 1. And are used as antiwear, antioxidant and friction modifiers in lubricating oil compositions such as automotive transmission fluids.
Patent Document 8 discloses sulfur obtained by reacting at least one sulfur composition with a di- or tri-hydrocarbyl phosphite and / or an amine compound as a useful additive in fuel and lubricating and functional fluid compositions. Phosphorus and nitrogen containing derivatives of the containing compounds are disclosed.

Patent Document 9 and Patent Document 10 include (1) β-hydroxythioether reactant, (2) dihydrocarbyl hydrogen phosphite, trihydrocarbyl phosphite and mixtures thereof, (3) specific nucleophilic reactants, The reaction product of a reaction mixture containing is disclosed and used as an antiwear and antioxidant agent.
In Patent Document 11, the general formula (RX'-R'-Y ') _m- P- (OH) _3-m
[Wherein, X ′ represents S (sulfur) and Y ′ represents S (sulfur) or O (oxygen). R represents an organic group having 6 to 20 carbon atoms, and R ′ represents an organic group having 1 to 6 carbon atoms. m is an integer of 1-3. ]
And general formula

[In the formula, X ′, Y ′, R and R ′ are the same as above. p represents an integer of 0 to 2, q represents an integer of 0 or 1, and is not 0 at the same time. And phosphorous compounds containing sulfur and sulfur.
In Patent Document 12, the general formula A- (RO)-(R'O) -P- (O) _m [wherein A is H or OH, m is 0 or 1, and when m is 0, A is When OH and m are 1, A represents H or OH, and R and R ′ each represent H or a hydrocarbon containing at least one S or O. ] The composition obtained by heat-processing the imide dispersing agent containing phosphoric acid and / or phosphorous acid represented by these, and boron is disclosed.
Patent Document 13 includes a general formula.

[Wherein, R represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, X represents O or S, respectively, and Z represents a metal atom. ] And is used as an additive for maintaining the base number and preventing wear.
However, when these conventional additives are used in lubricating oils, the extreme pressure properties, wear resistance and friction characteristics under severe conditions under high load have not yet been satisfactory.

U.S. Pat. No. 2,750,342 U.S. Pat. No. 2,960,523 U.S. Pat. No. 3,446,738 U.S. Pat. No. 4,081,387 US Pat. No. 4,511,480 US Pat. No. 4,579,672 US Pat. No. 4,776,969 WO88 / 03554 pamphlet WO89 / 12666 pamphlet Japanese National Patent Publication No. 3-500061 Japanese Patent Laid-Open No. 11-171892 US Pat. No. 6,352,962 JP 2002-294271 A

  The present invention has been made under such circumstances, and provides a novel sulfur-containing organophosphorus compound and an additive for lubricating oil containing the compound, and further provides a high load such as an internal combustion engine and a drive train machine. An object of the present invention is to provide a lubricating oil composition having excellent extreme pressure properties, wear resistance and friction characteristics even under severe operating conditions.

As a result of intensive studies by the present inventors to achieve the above object, the specific phosphate ester derivative is excellent in thermal stability, oxidation stability, NOx resistance and base number maintenance, and is extremely It has been found useful as a pressure agent, an antiwear agent, and a friction property modifier, and the present invention has been completed.
That is, the present invention provides the following additives for lubricants and the like.
1. General formula [I]

[Wherein Y represents S (sulfur) or O (oxygen). R ¹ represents an organic group having 4 to 24 carbon atoms, and R ² represents a divalent organic group having 1 to 6 carbon atoms. n shows the integer of 1-3. ]
The additive for lubricants which consists of phosphate ester derivative (A) represented by these.
2. General formula [I]

[Wherein Y represents S (sulfur) or O (oxygen). R ¹ represents an organic group having 4 to 24 carbon atoms, and R ² represents a divalent organic group having 1 to 6 carbon atoms. n shows the integer of 1-3. ]
A lubricant additive comprising a reaction product of a phosphate ester derivative (A) and a zinc compound (B) represented by the formula:
3. General formula [I]

[Wherein Y represents S (sulfur) or O (oxygen). R ¹ represents an organic group having 4 to 24 carbon atoms, and R ² represents a divalent organic group having 1 to 6 carbon atoms. n shows the integer of 1-3. ]
The additive for lubricants which consists of a mixture of the phosphoric acid ester derivative (A) represented by these, and an organic zinc compound (C).
4. The additive for lubricant according to any one of 1 to 3 above, wherein in the general formula (I), Y is a phosphate ester derivative of O (oxygen).
5. The lubricant according to 2 above, wherein the zinc compound (B) is at least one compound selected from the group consisting of zinc metal, zinc oxide, organic zinc compound, zinc oxyacid salt, zinc halide and zinc complex. Additive.
6. The additive for lubricant according to 2 above, wherein the zinc compound (B) is at least one compound selected from the group consisting of zinc, zinc oxide, zinc hydroxide, zinc carbonate, dimethyl zinc, diphenyl zinc and zinc complexes. .
7. The lubricant according to 3 above, wherein the organic zinc compound (C) is at least one compound selected from the group consisting of zinc alkylcarboxylate, zinc alkenylcarboxylate, zinc alkylphenylcarboxylate and zinc alkenylphenylcarboxylate. Additive.
8. The lubricant according to 3 above, wherein the organic zinc compound (C) is at least one compound selected from the group consisting of zinc oleate, zinc isostearate, zinc stearate, zinc alkylphenylcarboxylate, and zinc alkylsalicylate. Additive.
9. A lubricant additive composition comprising the lubricant additive according to any one of 1 to 8 above.
10. A lubricating oil composition comprising the lubricating base oil containing 0.001 to 0.5 mass% of the additive for lubricant according to any one of 1 to 8 above in terms of phosphorus element.
11. Lubricating oil for internal combustion engines, characterized in that the lubricating base oil contains 0.001 to 0.5 mass% of the additive for lubricant according to any one of 1 to 8 above in terms of phosphorus element. Composition.
12. A method for producing an additive for lubricant, which is obtained by reacting the phosphate ester derivative (A) and the zinc compound (B) according to 2 or 4 above.

The lubricating oil composition of the present invention is extremely excellent in base number retention under NOx atmosphere, that is, long drain performance, and further has excellent wear prevention performance and high temperature cleaning performance.
Therefore, lubricating oils for internal combustion engines with high NOx gas concentration and relatively high temperatures, such as gasoline engines, diesel engines, and gas engines, natural gas, LPG (liquefied petroleum gas), cracked gas, coal cracking It is effectively used as crankcase oil for internal combustion engines that use gas or the like as fuel. Further, the lubricating oil composition of the present invention is a lubricating oil that requires base number maintenance, wear prevention performance and high temperature cleanliness, such as lubricating oil for power transmission, gear oil, bearing oil, shock absorber oil. It can also be used as industrial lubricating oil.

1st invention of this application is an additive for lubricants which consists of a phosphate ester derivative (A) which is represented by the said general formula [I].
In the general formula [I], R ¹ is preferably a hydrocarbon group having 4 to 24 carbon atoms, particularly 8 to 16 carbon atoms.
Are preferred. When the carbon number of R ¹ is smaller than 4, the oil solubility, extreme pressure characteristics, wear resistance characteristics, friction characteristics, and lubrication characteristics are inferior and the corrosivity increases. Specifically, R ¹ is a butyl group, a pentyl group, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, various undecyl groups, various dodecyl groups, various tridecyl groups, various tetradecyl groups. , Various pentadecyl groups, various hexadecyl groups, various heptadecyl groups, various octadecyl groups, various nonadecyl groups, various eicodecyl groups and other alkyl groups; cyclohexyl group, various methylcyclohexyl groups, various ethylcyclohexyl groups, various propylcycloalkyl groups, various dimethyl groups Cycloalkyl groups such as cycloalkyl groups; phenyl groups, various methylphenyl groups, various ethylphenyl groups, various propylphenyl groups, various trimethylphenyl groups, various butylphenyl groups, various naphthyl groups, and other aryl groups; benzyl groups, various phenylethyl groups Groups, various methylbenzyl groups, various phenylpropyl groups, and arylalkyl groups such as various phenylbutyl group and the like.
In the general formula [I], R ² is preferably a hydrocarbon group having 1 to 6 carbon atoms, particularly preferably an alkylene group having 1 to 4 carbon atoms. Specifically, methylene group, ethylene group, 1,2-propylene group; 1,3-propylene group, various butylene groups, various pentylene groups, divalent aliphatic groups of various hexylene groups, cyclohexane, methylcyclopentane, etc. An alicyclic group having two bonding sites on the alicyclic hydrocarbon, various phenylene groups and the like can be mentioned.

Y represents S (sulfur) or O (oxygen), and contains at least one S as the general formula [I]. n represents an integer of 1 to 3, preferably 1 or 2, and more preferably 2.
Specific examples of the phosphate ester derivative represented by the above general formula [I] include tri (hexylthioethoxy) phosphate, tri (octylthioethoxy) phosphate, tri (dodecylthioethoxy) phosphate, (Hexadecylthioethoxy) phosphate, di (hexylthioethoxy) phosphate, di (octylthioethoxy) phosphate, di (dodecylthioethoxy) phosphate, di (hexadecylthioethoxy) phosphate Mono (hexylthioethoxy) phosphate, mono (octylthioethoxy) phosphate, mono (dodecylthioethoxy) phosphate, mono (hexadecylthioethoxy) phosphate, and the like.
Although there is no restriction | limiting in particular about the manufacturing method of the phosphate ester derivative represented by the said general formula [I], For example, a phosphate ester derivative is general formula [II]
R ¹ —S—R ² —YH (II)
[Wherein Y represents S (sulfur) or O (oxygen). R ¹ and R ² are the same as described above. Or an alkylthioalkyl alcohol represented by the general formula [III]
R ¹ —X—R ² —YNa (III)
[Wherein, X, Y, R ¹ and R ² are the same as described above. ]
Can be obtained by reacting phosphorus oxychloride (POCl ₃ ) with no catalyst or in the presence of a base.

In these reactions, the alkylthioalkyl alcohol or alkylthioalkoxide and phosphorus oxychloride are usually used at a molar ratio of 0.1 to 5.0 mol of alkylthioalkyl alcohol or alkylthioalkoxide per mol of phosphorus oxychloride. Preferably it is 1-3 mol, More preferably, it is the range of 1.5-2.5 mol.
The reaction temperature is usually selected in the range of -20 to 100 ° C, preferably -10 to 50 ° C. This reaction may be performed without a catalyst or in the presence of a base. As this base, for example, triethylamine, pyridine and the like can be used. In carrying out this reaction, a solvent such as xylene, toluene, THF, diethyl ether or the like can be used.

The second invention of the present application is an additive for a lubricant composed of a reaction product of the phosphate ester derivative (A) and the zinc compound (B).
As the zinc compound (B), metal zinc, zinc oxide, organic zinc compound, zinc oxyacid salt, zinc halide, zinc complex and the like are preferable. Specifically, zinc, zinc oxide, zinc hydroxide, zinc carbonate, Examples include dimethylzinc, diphenylzinc, and zinc complexes.
The reaction of the phosphate ester derivative (A) and the zinc compound (B) can be obtained by reacting in the absence of a catalyst or in the presence of a catalyst. In this reaction, the use ratio of the phosphate ester derivative and the zinc compound is usually 0.1 to 5.0 mol, preferably 1 to 3 mol of the phosphate ester derivative with respect to 1 mol of the zinc compound in a molar ratio. More preferably, it is the range of 1.5-2.5 mol.
The reaction range is usually selected in the range of room temperature to 200 ° C, preferably 40 to 150 ° C. In carrying out this reaction, a solvent such as xylene, toluene, hexane or the like can be used.

The third invention of the present application is an additive for a lubricant composed of a mixture of a phosphate ester derivative (A) and an organic zinc compound (C).
As the organic zinc salt (C), zinc alkyl or alkenyl carboxylate, zinc alkyl or alkenyl phenyl carboxylate and the like are preferable. Specifically, zinc oleate, zinc isostearate, zinc stearate, zinc alkylphenylcarboxylate, alkyl Examples include zinc salicylate.
As described above, the additive for lubricant in the present invention can be used only with the phosphate ester derivative (A), but the reaction product of the component (A) with the zinc compound (B), or the component (A) It is preferably used as a mixture with the organozinc compound (C). These reactants and mixtures may be one kind or two or more kinds.
The effective amount of these additives varies depending on the use, but is usually 0.001 to 1.0% by mass, preferably 0.005 to 0.5% by mass in terms of phosphorus element, based on the base oil. It is preferable to contain.

Mineral oil and synthetic oil can be used as the lubricating base oil. There are various mineral oils and synthetic oils, and they may be appropriately selected according to the use. Examples of mineral oil include paraffinic mineral oil, naphthenic mineral oil, intermediate base mineral oil, etc. Specific examples include light neutral oil, medium neutral oil, heavy neutral oil, bright stock by solvent refining or hydrogenation refining. And so on.
On the other hand, as synthetic oil, for example, poly α-olefin, α-olefin copolymer, polybutene, alkylbenzene, polyol ester, dibasic acid ester, polyhydric alcohol ester, polyoxyalkylene glycol, polyoxyalkylene glycol ester, polyoxyalkylene glycol Examples include ethers and cycloalkane compounds.
These lubricating base oils can be used alone or in combination of two or more kinds, and mineral oil and synthetic oil may be used in combination.
In the additive composition for lubricants of the present invention, various additive components conventionally used in lubricant compositions, for example, detergent dispersants, antioxidants, and the like, as long as the object of the present invention is not impaired. An agent, a rust preventive agent, a defoaming agent, a viscosity index improver, a pour point depressant, a demulsifier, another extreme pressure agent, an antiwear agent, and the like can be blended.

EXAMPLES Next, although an Example demonstrates this invention, this invention is not limited at all by these examples.
Example 1
In a 500 ml flask, 13.2 g (0.55 mol) of sodium hydride and 100 ml of xylene are placed under a nitrogen stream, and a solution of 95.2 g (0.5 mol) of octylthioethanol in xylene (100 ml) is stirred. While dripping. The reaction was carried out for 5 hours while refluxing.
On the other hand, 38.3 g (0.25 mol) of phosphorus oxychloride and 100 ml of THF were placed in a 1000 ml flask under ice-cooling under a nitrogen stream. The aforementioned reaction mixture was added dropwise over 2 hours, and then reacted at room temperature for 1 hour.
To the reaction solution, 10 g (0.55 mol) of water was added dropwise and stirred at room temperature for 1 hour, and then 100 ml of water was added and stirred at room temperature for 1 hour. The organic layer and the aqueous layer are separated by standing, 100 ml of water is added to the organic layer again, and the mixture is stirred at room temperature. Do this twice. Xylene and THF were distilled from the organic layer, and unreacted octylthioethanol and by-product octylthioethyl chloride were removed by distillation under reduced pressure. The yield of produced octylthioethyl phosphoric acid was 75 g.

Example 2
A 300 ml flask is charged with 45 g of octylthioethyl phosphoric acid obtained in Example 1, 50 ml of toluene and 1 g of water, and the temperature is raised to 70 ° C. 4.1 g (0.05 mol) of zinc oxide was added. The reaction was carried out at 70 ° C. for 3 hours. Toluene and water were distilled off under reduced pressure, then diluted with 15 g of 150N equivalent mineral oil, and the reaction product was filtered. The yield of the obtained reaction product was 60 g.
Example 3
In Example 1, it implemented like Example 1 except having used 123.3 g (0.5 mol) of dodecyl thioethanol instead of octyl thioethanol. The yield of the obtained reaction product (dodecylthioethyl phosphoric acid) was 92 g.
Example 4
The same procedure as in Example 2 was performed except that 55 g of the reaction product (dodecylthioethyl phosphoric acid) obtained in Example 3 was used instead of the reaction product obtained in Example 1. Carried out. The yield of the obtained reaction product was 70 g.

Example 5
In Example 1, it implemented like Example 1 except having used 81.1 g (0.5 mol) of hexyl thioethanol instead of octyl thioethanol. The yield of the obtained reaction product (hexylthioethyl phosphoric acid) was 61 g.
Example 6
In Example 2, the same procedure as in Example 2 was used except that 33 g of the reaction product (hexylthioethyl phosphoric acid) obtained in Example 5 was used instead of the reaction product obtained in Example 1. Carried out. The yield of the obtained reaction product was 50 g.
Example 7
In Example 1, it implemented like Example 1 except having used 42.2 g (0.275 mol) of phosphorus oxychloride instead of 38.3 g (0.25 mol) of phosphorus oxychloride. The yield of the obtained reaction product (octylthioethyl phosphoric acid) was 62 g.
Example 8
The same procedure as in Example 2 was performed except that the reaction product (octylthioethyl phosphate) obtained in Example 7 was used instead of the reaction product obtained in Example 1. did. The yield of the obtained reaction product was 60 g.

Example 9
In Example 1, it implemented like Example 1 except having used 34.5 g (0.225 mol) of phosphorus oxychloride instead of 38.3 g (0.25 mol) of phosphorus oxychloride. The yield of the obtained reaction product was 78 g.
Example 10
In Example 2, the reaction product obtained in Example 9 was used in the same manner as in Example 2 except that the reaction product (octylthioethyl phosphoric acid) obtained in Example 9 was used instead of the reaction product obtained in Example 1. did. The yield of the obtained reaction product was 61 g.
Example 11
A 500 ml flask was charged with 112.8 g (0.4 mol) of oleic acid, 16.2 g (0.2 mol) of zinc oxide, 50 ml of toluene and 2 g of water, and reacted at 70 ° C. for 3 hours. Toluene and water were distilled off under reduced pressure, and the residue was diluted with 30 g of mineral oil equivalent to 150 N, and the reaction product was filtered. The yield of the obtained reaction product was 145 g.
Example 12
In Example 11, it carried out like Example 11 except having used 113.6 g (0.4 mol) of stearic acid instead of oleic acid. The yield of the obtained reaction product was 148 g.
Example 13
In Example 11, it carried out like Example 11 except having used 122.4 g (0.4 mol) of dodecyl salicylic acid instead of oleic acid. The yield of the obtained reaction product was 156 g.

Examples 14 to 21 and Comparative Examples 1 and 2
By adding the phosphate ester derivative obtained above or a commercially available antiwear agent or phosphate dibutyl ester and various additives to the base oil of 100N mineral oil or 500N mineral oil according to the formulation in Table 1, the lubricating oil of the present invention Compositions (Examples 14 to 21) and comparative lubricating oil compositions (Comparative Examples 1 and 2) were prepared.

(note)
* 1 Hydrorefined mineral oil, 100 ° C kinematic viscosity 4.5mm ² / s, sulfur content 0.0% by mass or less
* 2 Hydrorefined mineral oil, kinematic viscosity at 100 ° C 10.9 mm ² / s, sulfur content 0.01% by mass or less
* 3 Zinc secondary dialkyldithiophosphate, phosphorus content 8.2% by mass, zinc content 9.0% by mass, sulfur content 17.1% by mass
* 4 Ca salicylate, Ca: 7.94% by mass
* 5 Polybutenyl succinimide, nitrogen content 1.56% by mass
* 6 Boron-modified polybutenyl succinimide, nitrogen content 1.76% by mass, boron content 2.0% by mass
* 7 Mixture of dialkyldiphenylamine and hindered phenol antioxidant
* 8 Metal deactivators, antifoaming agents, demulsifiers, etc.

About each composition obtained by the above, the NOx resistance test, the valve-wear abrasion test, and the Falex load-bearing capacity test were done by the following method.
(1) NOx resistance test 250 ml of sample oil was charged with 6 liter / hr of nitric oxide (NO) gas at a concentration of 8000 ppm in the presence of iron and copper catalyst (test piece of oxidation test JIS K-2514) and air. Blowing was performed at a rate of 6 liters / hr. The base oil number (hydrochloric acid method) was measured when the temperature of the sample oil was kept at 140 ° C. and forcedly deteriorated. The smaller the base number decrease, the higher the base number maintainability even in a nitrogen oxide gas atmosphere used in an internal combustion engine, indicating that the lubricating oil can be used for a longer period of time.
(2) Valve system wear test A JASO M 328-95 valve system wear test was performed, and the rocker arm pad scuff area, rocker arm wear amount, and cam wear amount after 100 hours test were measured. Each value of 10 or less indicates a lubricating oil composition having excellent wear resistance.
(3) Falex load-bearing capacity test Pin material: AISI-3153, block material: AISI-1137, oil amount: 300 mL, rotation speed: 290 rpm, oil temperature: 100 ° C., load 1112 N After the operation, the load was continuously increased at an oil temperature of 100 ° C., and the seizure load was measured according to ASTM D3233. The higher the seizure load, the more excellent the load bearing capacity.

From the NOx resistance test results shown in Table 2 above, the lubricating oil compositions (Examples 14 to 21) of the present invention show excellent base number retention in a nitrogen oxide gas atmosphere. On the other hand, in Comparative Example 1 in which the antiwear agent in the present invention was replaced with zinc dithiophosphate and tested in the same manner, it was found that the base number maintenance characteristics were remarkably inferior.
Further, from the results of the valve train wear test shown in Table 3, the lubricating oil compositions of the present invention (Examples 14 and 19) are excellent in wear resistance performance, but in Comparative Example 1, the wear resistance performance is low. It turns out that it is remarkably inferior.
Comparative Example 2 shows excellent base number durability under a nitrogen atmosphere (Table 2), and also has excellent wear resistance (Table 3), but the load bearing performance is the lubricating oil composition of the present invention (Examples). 14 and 19) (Table 4).

The lubricating oil composition of the present invention can be used, for example, as an internal combustion engine lubricating oil, a power transmission lubricating oil, a gear oil, a bearing oil, a shock absorber oil, an industrial lubricating oil, and the like.

Claims (12)

Formula [I]

[Wherein Y represents S (sulfur) or O (oxygen). R ¹ represents an organic group having 4 to 24 carbon atoms, and R ² represents a divalent organic group having 1 to 6 carbon atoms. n is an integer of 1 to 3. ]
The additive for lubricants which consists of phosphate ester derivative (A) represented by these. Formula [I]

[Wherein Y represents S (sulfur) or O (oxygen). R ¹ represents an organic group having 4 to 24 carbon atoms, and R ² represents a divalent organic group having 1 to 6 carbon atoms. n is an integer of 1 to 3. ]
A lubricant additive comprising a reaction product of a phosphate ester derivative (A) and a zinc compound (B) represented by the formula: Formula [I]

[Wherein Y represents S (sulfur) or O (oxygen). R ¹ represents an organic group having 4 to 24 carbon atoms, and R ² represents a divalent organic group having 1 to 6 carbon atoms. n is an integer of 1 to 3. ]
The additive for lubricants which consists of a mixture of the phosphoric acid ester derivative (A) represented by these, and an organic zinc compound (C). In the said general formula (I), Y is O (oxygen), The additive for lubricants in any one of Claims 1-3. The additive for lubricant according to claim 2, wherein the zinc compound (B) is at least one compound selected from the group consisting of metal zinc, zinc oxide, organic zinc compound, zinc oxyacid salt, zinc halide and zinc complex. Agent. The additive for lubricant according to claim 5, wherein the zinc compound (B) is at least one compound selected from the group consisting of zinc, zinc oxide, zinc hydroxide, zinc carbonate, dimethyl zinc, diphenyl zinc and zinc complexes. The additive for lubricant according to claim 3, wherein the organic zinc compound (C) is at least one compound selected from the group consisting of zinc alkylcarboxylate, zinc alkenylcarboxylate, zinc alkylphenylcarboxylate and zinc alkenylphenylcarboxylate. Agent. The additive for lubricant according to claim 7, wherein the organic zinc compound (C) is at least one compound selected from the group consisting of zinc oleate, zinc isostearate, zinc stearate, zinc alkylphenylcarboxylate and zinc alkylsalicylate. Agent. The additive composition for lubricants which mix | blends the additive for lubricants in any one of Claims 1-8. A lubricating oil composition comprising the lubricating base oil containing 0.001 to 0.5 mass% of the additive for lubricant according to any one of claims 1 to 8 in terms of phosphorus element. A lubricating oil composition for an internal combustion engine, characterized in that the lubricating base oil contains 0.001 to 0.5 mass% of the additive for lubricant according to any one of claims 1 to 8 in terms of phosphorus element. object. A method for producing an additive for lubricant, which is obtained by reacting the phosphate ester derivative (A) according to claim 2 or 4 with a zinc compound (B).