JP5497982B2 - Lubricating oil composition for transmission oil - Google Patents

Description

  The present invention relates to lubricating oil compositions, particularly transmission oils.

  Since automobile transmissions are used under high-speed and high-load conditions, transmission oils used for them are required to have excellent anti-seizure properties and wear resistance. On the other hand, improvement in fuel consumption is also required. As a method of improving fuel efficiency, methods of lowering friction by lowering viscosity or adding a friction modifier were common, but lowering friction by adding a friction modifier reduces the malfunction of the synchro synchronization mechanism in the case of a manual transmission. In order to generate this, a technique for improving fuel efficiency by reducing viscosity has been mainly employed.

  However, lowering the viscosity of the lubricant may cause problems such as reduced seizure resistance and damage to equipment. For automotive transmission oils, sulfurized olefins and sulfurized esters are used to increase seizure resistance. An extreme pressure agent such as a sulfur-based additive such as phosphoric acid ester or a phosphoric acid-based additive such as an amine salt of phosphoric acid ester has been added in an increased amount. (Patent Document 1) (Patent Document 2) (Patent Document 3)

  In recent years, due to the rapid increase in demand for high-speed transportation using highways, the specific gravity of high-speed driving of automobiles has increased. In addition, measures such as higher engine output and improved aerodynamic characteristics have made transmission gear units more compact. As a result, the temperature of transmission oil used in manual transmissions and reduction gears has increased significantly in the machine.

  In order to cope with this, it is necessary to add an extreme amount of an extreme pressure agent such as the above-mentioned sulfurized olefin or phosphoric acid ester having a high anti-seizure property, and as a result, oxidation stability at a high temperature (usually 150 ° C. or higher). There is a strong tendency to promote defects and corrosive wear, resulting in problems such as corrosion and sludge formation on metals, particularly copper, and as a result, a phenomenon of promoting gear tooth surface wear and seizure may occur. In addition, in manual transmissions, the synchronizer ring and gear cone portion of the synchromesh mechanism cause a friction coefficient drop or abnormal wear, resulting in problems such as poor synchronization, increased shift force, and inability to shift. Sometimes.

For these reasons, recently, in order to solve the shift synchronization problem, a metal detergent-zinc dithiophosphate system has been proposed from the above-described sulfur-phosphorus extreme pressure agent. However, it has been pointed out that sufficient extreme pressure performance cannot be obtained.
JP2004-262980 JP-A-10-259393 JP-A-10-316987

  The present invention is capable of extending the service life by maintaining a sufficient extreme pressure, low fatigue characteristics, high oxidation stability, and without losing seizure resistance performance even under high speed and high load operation conditions due to downsizing of the transmission. The lubricating oil composition is to be obtained.

In order to solve the above-mentioned problems, the present invention provides a base oil of mineral oil and / or synthetic oil, poly (meth) acrylate containing a hydroxyl group and poly (meth) acrylate not containing a hydroxyl group, and conventionally has a low extreme pressure. And a mass ratio of the poly (meth) acrylate having a hydroxyl group and a poly (meth) acrylate having no hydroxyl group is 83. 3:16. 7 to 40:60, the FALEX seizure test result of the composition is 907.2 Kg (2000 lbs) or more, the ISOT test (kinematic viscosity increase rate at 40 ° C. and 100 ° C.) is 8% or less, FZG The result is a lubricating oil composition for transmission oils having a pitching test result of 48 hours or longer.
Furthermore, a lubricating oil composition is obtained by containing a dihydrocarbylcarbamic acid derivative.

  According to the present invention, a lubricating oil composition having good seizure resistance performance, extreme pressure equal to or higher than that of a sulfur-phosphorus extreme pressure agent, low fatigue characteristics, high oxidation stability, and long life. The transmission can be downsized, and sufficient lubrication performance can be obtained even under conditions of high speed and high load operation.

  The lubricating base oil in the lubricating oil composition of the present invention is not particularly limited, and a mineral base oil and / or a synthetic base oil used for ordinary lubricating oils can be used. These mineral oil base oils and synthetic base oils can be used by mixing appropriate mineral oil base oils, synthetic base oils, and mineral oil base oils and synthetic base oils in an arbitrary ratio.

The viscosity index of the lubricating base oil is not particularly limited, but the value is preferably 90 or more, more preferably 100 or more, and most preferably 110 so that excellent viscosity characteristics can be obtained from low temperature to high temperature. That's it.
The upper limit of the viscosity index is not particularly limited, and those having about 135 to 180, such as normal paraffin, slack wax, GTL (gas-liquid) wax, or isoparaffin mineral oil obtained by isomerizing these, or complex ester group Oils and oils of about 150 to 250 such as PAO (poly α-olefin) base oil can also be used.
When the lubricating base oil has a viscosity index of less than 90, the added amount of poly (meth) acrylate, which is a viscosity index improver to be added, or the use of poly (meth) acrylate having a large molecular weight, shear stability May get worse.

  Specifically, as the mineral base oil, the lubricating oil fraction obtained by subjecting the crude oil to atmospheric distillation obtained under reduced pressure is subjected to solvent removal, solvent extraction, hydrocracking, Examples of the lubricating base oil include those refined by one or more treatments such as solvent dewaxing and hydrorefining, or wax isomerized mineral oil.

The lubricating base oil other than the above-described mineral oil base oil is not particularly limited, and a conventionally used synthetic oil can be used. It is appropriately selected and selected according to the application and used in any ratio with the mineral oil. be able to. For example, poly-α-olefin, α-olefin copolymer, polybutene, polyol ester, dibasic acid ester, polyhydric alcohol ester, polyoxyalkylene glycol, polyoxyalkylene glycol ester, polyoxyalkylene glycol ether, cycloalkane compound, etc. Can be mentioned.
Moreover, the lubricating base oil etc. which are manufactured by the method of isomerizing GTL WAX (Gas Liquid Wax) manufactured from natural gas by the Fischer-Tropsch process etc. can be illustrated.

The upper limit of the kinematic viscosity at 100 ° C. of the base oil is 8 mm ² / s, preferably 6 mm ² / s. On the other hand, the lower limit of the kinematic viscosity at 100 ° C. of the base oil is 2 mm ² / s, preferably 3 mm ² / s. When the kinematic viscosity at 100 ° C. is less than 2 mm ² / s, the oil film is not sufficiently formed at the lubrication point, so that the lubricity is poor and the tooth surface is seized and worn, and the base oil has a large evaporation loss. May be.

The base oil of the present invention contains a metal salt of dithiophosphate. As the dithiophosphoric acid metal salt, zinc dialkyldithiophosphate and / or molybdenum dialkyldithiophosphate are used, and the alkyl group is usually a primary or secondary alkyl group having 3 to 22 carbon atoms, carbon number. Zinc dialkyldithiophosphates and / or molybdenum dialkyldithiophosphates having alkylaryl groups substituted with 3-18 alkyl groups are used.
These zinc dialkyldithiophosphates, molybdenum dialkyldithiophosphates and the like can be used singly or in combination of two or more, and in particular, those mainly composed of zinc dialkyldithiophosphate having a secondary alkyl group. From the viewpoint of improving wear resistance, it is preferable.

  Specific examples of the zinc dialkyldithiophosphate include zinc dipropyldithiophosphate, zinc dibutyldithiophosphate, zinc dipentyldithiophosphate, zinc dihexyldithiophosphate, zinc diisopentyldithiophosphate, zinc diethylhexyldithiophosphate, zinc dioctyldithiophosphate, Zinc dinonyl dithiophosphate, zinc didecyl dithiophosphate, zinc didodecyl dithiophosphate, zinc dipropylphenyl dithiophosphate, zinc dipentylphenyl dithiophosphate, zinc dipropylmethylphenyl dithiophosphate, zinc dinonylphenyl dithiophosphate, didodecylphenyl dithiophosphorus Zinc acid, zinc dodecylphenyl dithiophosphate, etc. are mentioned.

  Specific examples of the molybdenum dialkyldithiophosphate include molybdenum dipropyldithiophosphate, molybdenum dibutyldithiophosphate, molybdenum dipentyldithiophosphate, molybdenum dihexyldithiophosphate, molybdenum diisopentyldithiophosphate, molybdenum diethylhexyldithiophosphate, molybdenum dioctyldithiophosphate, Molybdenum dinonyldithiophosphate, molybdenum didecyldithiophosphate, molybdenum didodecyldithiophosphate, molybdenum dipropylphenyldithiophosphate, molybdenum dipentylphenyldithiophosphate, molybdenum dipropylmethylphenyldithiophosphate, molybdenum dinonylphenyldithiophosphate, didodecylphenyldithiophosphorus Molybdate, molybdenum didodecylphenyldithiophosphate, etc.

  The zinc dialkyldithiophosphate and / or molybdenum dialkyldithiophosphate is about 0.02 to 1% by mass, preferably 0.04 to 0.5% by mass, more preferably 0, as the zinc content in the lubricating oil composition. 0.08 to 0.4% by mass, and the molybdenum content in the lubricating oil composition is 0 to 0.2% by mass, preferably 0 to 0.1% by mass, more preferably 0 to 0% by mass. It mix | blends so that it may become 0.05 mass%.

  This lubricating oil composition contains a poly (meth) acrylate containing a hydroxyl group together with the dithiophosphate metal salt. The poly (meth) acrylate containing a hydroxyl group is a copolymer, and an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms and a hydroxyl group-containing vinyl monomer are essential constituent monomers. It is a copolymer.

As the alkyl (meth) acrylate (a) having an alkyl group having 1 to 20 carbon atoms, specifically,
(A1) Alkyl (meth) acrylate having an alkyl group having 1 to 4 carbon atoms:
For example, methyl (meth) acrylate, ethyl (meth) acrylate, n- or iso-propyl (meth) acrylate, n-, iso- or sec-butyl (meth) acrylate (a2) an alkyl group having 8 to 20 carbon atoms. Alkyl (meth) acrylate having:
For example, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-decyl (meth) acrylate, n-isodecyl (meth) acrylate, n-undecyl (meth) acrylate, n-dodecyl (meth) acrylate, 2-methylundecyl (meth) acrylate, n-tridecyl (meth) acrylate, 2-methyldodecyl (meth) acrylate, n-tetradecyl (meth) acrylate, 2-methyltridecyl (meth) acrylate, n-pentadecyl (meta ) Acrylate, 2-methyltetradecyl (meth) acrylate, n-hexadecyl (meth) acrylate, and n-octadecyl (meth) acrylate, n-eicosyl (meth) acrylate, n-docosyl (meth) acrylate, dovanol 23 Such methacrylate Mitsubishi Chemical methacrylate oxo alcohol mixture on the Co., Ltd. 12 carbon atoms / carbon atoms 13, Dobanol 45 [carbons manufactured by Mitsubishi Chemical Corporation 13 / number 14 oxo alcohol mixture of carbon,
(A3) Alkyl (meth) acrylate having an alkyl group having 5 to 7 carbon atoms:
Examples thereof include n-pentyl (meth) acrylate and n-hexyl (meth) acrylate.

  Of the above (a1) to (a3), preferred are the substances belonging to (a1) and (a2), and more preferred is the substance (a2). Among the above (a1), those having 1 to 2 carbon atoms of the alkyl group are preferable from the viewpoint of the viscosity index. Among the above (a2), preferred are those having 10 to 20 carbon atoms, more preferably 12 to 14 carbon atoms, from the viewpoint of solubility in base oil and low temperature characteristics.

One or more (preferably 1 or 2) hydroxyl group-containing vinyl monomers (b) constituting the copolymer with the above alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms. It is a vinyl monomer containing the hydroxyl group. As a specific example,
(B1) Hydroxyalkyl (C2-6) (meth) acrylate:
For example, 2-hydroxyethyl (meth) acrylate, 2 or 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 1-methyl-2-hydroxyethyl (meth) acrylate, etc.
(B2) Mono- or di-hydroxyalkyl (C1-C4) substituted (meth) acrylamide:
For example, N, N-dihydroxymethyl (meth) acrylamide, N, N-dihydroxypropyl (meth) acrylamide, N, N-di-2-hydroxybutyl (meth) acrylamide, etc. (b3) Vinyl alcohol (hydrolysis of vinyl acetate units) Formed by decomposition),
(B4) Alkenol having 3 to 12 carbon atoms:
For example, (meth) allyl alcohol, crotyl alcohol, isocrotyl alcohol, 1-octenol, 1-undecenol, etc.
(B5) Alkene diol having 4 to 12 carbon atoms:
For example, 1-buten-3-ol, 2-buten-1-ol, 2-butene-1,4-diol, etc.
(B6) Hydroxyalkyl (C1-6) alkenyl (C3-10) ether: For example, 2-hydroxyethylpropenyl ether, etc.
(B7) Hydroxyl group-containing aromatic monomer: For example, o-, m- or p-hydroxystyrene (b8) Polyvalent (3 to 8 valent) alcohol:
For example, alkane polyol, intramolecular or intermolecular dehydrate, alkenyl (3 to 10 carbon atoms) ether or (meth) acrylate (for example, glycerin, pentaerythritol, sorbitol, sorbitan, diglycerin, sucrose) (for example, Sucrose (meth) allyl ether)
(B9) Vinyl monomer containing polyoxyalkylene chain and hydroxyl group:
For example, polyoxyalkylene glycol (alkylene group having 2 to 4 carbon atoms, polymerization degree 2 to 50) or polyoxyalkylene polyol {polyoxyalkylene ether of 3 to 8 valent alcohol (alkyl group having 2 to 4 carbon atoms, Mono (meth) acrylate or mono (meth) allyl ether {eg, polyethylene glycol (degree of polymerization 2-9) mono (meth) acrylate, polypropylene glycol (degree of polymerization 2-12) mono (meth) ) Acrylate, polyethylene glycol (degree of polymerization 2-30) mono (meth) allyl ether} and the like.

  Of the above (b1) to (b9), from the viewpoint of the effect of improving the viscosity index, preferred is (b1), particularly 2-hydroxyethyl methacrylate.

It is preferable that each ratio in the monomer which comprises the copolymer of the said poly (meth) acrylate containing a hydroxyl group becomes as follows from a viewpoint of a viscosity index.
The lower limit of the component (a) is preferably 50% by mass, more preferably 75% by mass, and the upper limit is preferably 95% by mass, more preferably 85% by mass.

The lower limit of the above (a1) is preferably 0% by mass, more preferably 1% by mass, and the upper limit is preferably 20% by mass, more preferably 10% by mass.
The lower limit of the above (a2) is preferably 50% by mass, more preferably 70% by mass, and the upper limit is 95% by mass, more preferably 90% by mass.

  The lower limit of the above (b) is preferably 5% by mass, more preferably 7% by mass, particularly preferably 11% by mass, and the upper limit is preferably 50% by mass, more preferably 30% by mass, and particularly preferably 15% by mass. %.

  The lower limit of the total of (a) + (b) is preferably 55% by mass, more preferably 82% by mass, and the upper limit is preferably 100% by mass.

The lower limit of the mass average molecular weight of the poly (meth) acrylate containing a hydroxyl group is preferably 5,000, more preferably 8,000, particularly preferably 10,000, and the upper limit is preferably 50,000, more preferably. Is 40,000, particularly preferably 35,000, particularly preferably 30,000.
When the mass average molecular weight is in the above range, good shear stability can be provided. The mass average molecular weight is determined by gel permeation chromatography, and is calculated in terms of polystyrene.
The mass average molecular weight can be adjusted by the polymerization temperature, monomer concentration (solvent concentration), catalyst amount or chain transfer agent amount.

  The dispersity (Mw / Mn) of the poly (meth) acrylate containing a hydroxyl group is preferably 1 to 2.5, more preferably 1.2 to 2, and particularly preferably 1.5 to 1.7. The smaller the degree of dispersion, the better the shear stability. Mn is obtained in the same manner as Mw.

  The solubility parameter has a lower limit of preferably 8.6, more preferably 9.2, particularly preferably 9.3, and an upper limit of preferably 11, more preferably 10.5, particularly preferably 9. 7. When the solubility parameter value is within the above range, the solubility in the base oil is further improved. The solubility parameter value was calculated by the Fedors method (Polym. Eng. Sci. 14 (2), 152, (1974).

  Furthermore, the HLB of the poly (meth) acrylate containing a hydroxyl group is preferably 0.5 to 7. When the HLB is within this range, the demulsibility is particularly good. More preferably, HLB is 1-6.5, Most preferably, it is 1.5-6. This HLB value is a value calculated by the HLB of the Oda method based on the concept of organic inorganicity (“New surfactant introduction”, published by Sanyo Chemical Industries, Ltd., P128).

  Moreover, the hydroxyl value of the poly (meth) acrylate containing a hydroxyl group used as an additive is 10 to 100, preferably 20 to 50, more preferably 25 to 35. The measurement of the hydroxyl value is a numerical value obtained by measurement according to JIS K3342 (1961), and is a value indicating the amount of hydroxyl group in the additive.

It is also effective to use a dihydrocarbylcarbamic acid derivative together with the dithiophosphate metal salt.
Examples of the dihydrocarbyl carbamic acid derivative include dihydrocarbyl carbamic acid aliphatic esters and dihydrocarbyl carbamic acid metal salts.
Examples of the dihydrocarbyl carbamic acid aliphatic ester include those represented by the general formula 1.

（式中、Ｒ¹は１ないし２０個の炭素原子およびｎに等しい遊離原子価を有する脂肪族基であり、Ｒ²およびＲ³は個別的に、１ないし２０個の炭素原子を有するアルキル基であり、ｎは１または２の整数である。）

Wherein R ¹ is an aliphatic group having 1 to 20 carbon atoms and a free valence equal to n, and R ² and R ³ are individually alkyl groups having 1 to 20 carbon atoms. And n is an integer of 1 or 2.)

As the dihydrocarbyl carbamate metal salt, zinc dihydrocarbyl carbamate and molybdenum dihydrocarbyl carbamate are preferable.
Examples of zinc dihydrocarbyl carbamate include zinc dithiocarbamate (ZnDTC). Examples of molybdenum dihydrocarbylcarbamate include molybdenum dithiocarbamate (MoDTC).

The zinc dihydrocarbylcarbamate is represented by the following general formula 2.

  In the above general formula 2, R and R ′ each independently represent an alkyl group having 1 to 18 carbon atoms. Examples of such an alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, linear or branched pentyl group, linear or branched hexyl group, linear or branched heptyl group, linear or branched Octyl group, linear or branched nonyl group, linear or branched decyl group, linear or branched undecyl group, linear or branched dodecyl group, linear or branched tridecyl group, straight Examples thereof include a linear or branched tetradecyl group, a linear or branched pentadecyl group, a linear or branched hexadecyl group, a linear or branched heptadecyl group, a linear or branched octadecyl group, and the like.

The alkyl group may be a so-called primary alkyl group in which the carbon atom bonded to the nitrogen atom is a primary carbon, or a so-called secondary alkyl group in which the carbon atom is secondary. A so-called tertiary alkyl group in which the carbon atom is tertiary may be used.
Among the compounds represented by the above general formula 2, zinc dialkyldihydrocarbylcarbamate in which R and R ′ are individually an alkyl group having 4 to 13 carbon atoms is a friction reducing effect of a new oil and sustaining the effect. It is particularly preferable in terms of giving a lubricating oil composition having excellent properties.

When the lubricating oil composition for an internal combustion engine is used, the content of the two components of the general formula is based on the total amount of the lubricating oil composition, and the lower limit is 0.01% by mass, preferably 0.1% by mass, On the other hand, the upper limit is 5% by mass, preferably 2% by mass.
When the content of the above two components of the general formula is less than 0.01% by mass, the friction reduction effect of the new oil is still insufficient. On the other hand, when it exceeds 5% by mass, the friction is reduced to match the content. Since there is no improvement in the effect, each should be avoided. In addition, as a general formula 2 component, you may use it with the form diluted with the solvent or lubricating oil from the ease of handling.

Preferable examples of the above-mentioned molybdenum dihydrocarbyl carbamate include those represented by the following general formula 3.
(Chemical formula 3)
(R ¹ R ² N-CS-S) ₂ Mo ₂ OpSq (3)

(In Formula 3, R ¹ and R ² each independently represent an alkyl group having 1 to 24 carbon atoms, preferably 3 to 18 carbon atoms, p is 0 to 3, q is 4 to 1, and p + q = 4)

  Examples of the molybdenum dialkyldithiocarbamate of the general formula 3 include, for example, molybdenum diethyldithiocarbamate, molybdenum dipropyldithiocarbamate, molybdenum dibutyldithiocarbamate, molybdenum dipentyldithiocarbamate, molybdenum dipentyldithiocarbamate, molybdenum dihexyldithiocarbamate, molybdenum dioctyldithiocarbamate, Molybdenum sulfide didecyl dithiocarbamate, sulfide molybdenum didodecyl dithiocarbamate, molybdenum di (butylphenyl) dithiocarbamate sulfide, molybdenum di (nonylphenyl) dithiocarbamate, sulfurized oxymolybdenum diethyldithiocarbamate, sulfurized oxymolybdenum dipropyldithiocarbamate, sulfurized oxymolybdenum dibutyldithiocarbamate Baa , Sulfurized oxymolybdenum dipentyldithiocarbamate, sulfurized oxymolybdenum dihexyldithiocarbamate, sulfurized oxymolybdenum dioctyldithiocarbamate, sulfurized oxymolybdenum didecyldithiocarbamate, sulfurized oxymolybdenum didodecyldithiocarbamate, sulfurized oxymolybdenum di (butylphenyl) dithiocarbamate, sulfurized oxymolybdenum di ( Nonylphenyl) dithiocarbamate and mixtures thereof.

  It is also possible to add a general conventional poly (meth) acrylate containing no hydroxyl group at the same time as the above-mentioned hydroxyl group-containing poly (meth) acrylate, the amount of which is the hydroxyl group-containing poly (meth) acrylate. : Hydroxyl group-free poly (meth) acrylate, which can be added at a mass ratio of 100: 0 to 40:60.

  Other additives such as rust preventives, detergents, dispersants, antioxidants, extreme pressure agents, oiliness agents, friction modifiers, pour point depressants, antifoaming agents, etc. should be added as necessary. You can also.

The following samples were prepared for the production of Examples 1 to 7 , Reference Examples 1 to 2 and Comparative Examples 1 to 5.
(1) Base oil (1-1) Base oil A: The oil type is API Gp. I, Gp. II, Gp. Mixed oil of III (characteristic: kinematic viscosity at 40 ° C .; 18.7 mm ² / s, kinematic viscosity at 100 ° C .; 4.1 mm ² / s, viscosity index; 122)
(1-2) Base oil B: The oil type is API Gp. I, Gp. II, Gp. V mixed oil (characteristic: kinematic viscosity at 40 ° C .; 16.5 mm ² / s, kinematic viscosity at 100 ° C .; 3.6 mm ² / s, viscosity index; 96)
(2) Poly (meth) acrylate (PMA) containing a hydroxyl group: mass average molecular weight (Mw); 16,000, hydroxyl value 30, (Sanyo Kasei Kogyo Co., Ltd., Include V1070)
(3) Conventional poly (meth) acrylate (PMA) containing no hydroxyl group
(3-1) Conventional PMA (I): Mass average molecular weight; 15,000, (Degussa, Viscoplex 0-050)
(3-2) Conventional PMA (II): Mass average molecular weight; 35,000, (manufactured by Sanyo Chemical Industries, Inc., 811)
(3-3) Conventional PMA (III): Mass average molecular weight; 75,000, (Degussa, Viscoplex 0-291)
(4) Zinc dialkyldithiophosphate (4-1) ZnDTP (I): primary diethylhexyl dithiophosphate zinc (4-2) ZnDTP (II): zinc dialkyldithiophosphate (as alkyl groups, isopropyl (C3) and 4-methyl (Secondary type 2 pentyl (C6) is about 4: 6)
(5) Dihydrocarbyl carbamic acid derivative (5-1) MoDTC: Molybdenum dihydrocarbyl carbamate (5-2) ZnDTC: Zinc dihydrocarbyl carbamate (5-3) DTC: Methylenebisdibutyldithiocarbamate (6) Phenol-based oxidation Inhibitor: IRGANOX-L135, benzenepropanoic acid, 3,5-bis (1,1 dimethyl-ethyl) -4hydroxy, C7-C9 side chain alkyl ester (7) Sulfurized oil and fat: Sulfurized lard oil, manufactured by Ciba Specialty Chemicals (8) Phosphate ester: alkylated triphenyl phosphate (9) Package additive: detergent + dispersant + antioxidant

Lubricating oils of Comparative Examples 1 to 5 for comparison with Examples 1 to 7 , Reference Examples 1 to 2 and Comparative Examples 1 to 5 using the above samples and mixing well according to the composition shown in Table 1, Table 2 and Table 3. A composition was obtained. In Comparative Example 5, a commercially available transmission oil was used.

(test)
In order to compare the performance of Examples, Reference Examples and Comparative Examples, the following tests were conducted.

(Property / Composition Measurement Test)
1. Kinematic viscosity at 40 ° C (unit: mm ² / s)
2, 100 ° C kinematic viscosity (unit: mm ² / s)
3. Viscosity index (VI)
4. Phosphorus content (unit: mass%)
5. Sulfur content (unit: mass%)

(FALEX seizure test)
(Test conditions): A test piece is set in a test apparatus, an oil tank containing 60 ml of test oil is heated by a heater, and the oil temperature is raised to 100 ° C.
When the oil temperature reaches 100 ° C., the drive motor of the test apparatus is started and a test is started with a load of 136.08 kg (300 pounds) applied to the block. Run at 136.08 kg (300 pounds) for 2 minutes, then increase the load to 226.8 kg (500 pounds) and run for 1 minute. Thereafter, increase the load by 136.08 kg (300 lbs), run for 1 minute each, and repeat until seizure occurs.
(Test piece): (1) FALEX # 8 TEST PIN
(2) FALEX XEE BLOCK (STANDARD)
(Determination): The occurrence of burn-in is determined by the sudden increase in friction torque, the generation of an abnormal noise “key”, or the breakage of the pin.
The heater is stopped when it reaches 100 ° C., and the test is continued in that state.
The higher the value, the better the seizure resistance.

(ISOT test)
Compared with the new oil, the sample after conducting the oxidation test under the conditions of 135 ± 0.5 ° C. × 96 hr in accordance with JIS K2514 is 40 ° C. kinematic viscosity change rate (increase rate) and 100 ° C. kinematics. The viscosity change rate (rise rate) is measured. A thing with a small increase rate is favorable, and makes a pass value 8 or less.

(SONIC test)
Under the test conditions specified in JASO M347-95, 30 ml of sample was irradiated with ultrasonic waves for 1 hour, and the kinematic viscosity change rate (reduction rate) at 40 ° C. and the kinematic viscosity change rate (reduction rate) at 100 ° C. with the new oil. taking measurement. A thing with a small fall rate is favorable, and makes a pass value 7 or less.

(FZG pitching test)
Conforms to DIN 51354. TYPE PT-C gear, load is 9 stage, oil temperature is 120 ° C, rotation speed is 1440 / min.
In the fatigue life determination method, the test apparatus is stopped, the tooth surface is regularly observed, and the time (hr) when 1 mm ² of pitching occurs is set. The observation interval is every 8 hours for the first 24 hours and every 2 to 4 hours thereafter.

(result)
The results of the above tests are shown in Table 1, Table 2, and Table 3.
(Discussion)
In each of Examples 1 to 7 , in the FALEX seizure test, all were 907.2 kg (2000 lbs) or more, and good results in seizure resistance were obtained. Further, in the FZG pitching test, it was 48 to 78 hours, and in particular, in Examples 1 and 5 to 7, it was 72 hours or more and a long fatigue life was obtained. Furthermore, a certain level of good results have been obtained in the ISOT test and the SONIC test. In Example 4, although the kinematic viscosity of the new oil is high, the rate of increase in kinematic viscosity in the ISOT test is within the acceptable value. In Reference Example 2 , particularly excellent results were obtained in the rate of decrease in viscosity in the SONIC test.
In Comparative Examples 1, 2, and 4, zinc dialkyldithiophosphate (ZnDTP (II)) was used, but conventional PMA not containing a hydroxyl group was used. Comparative Example 1 was an ISOT test and a SONIC test. In the FALEX image sticking test, 567 kg (= 1250 pounds), which is inferior in the image sticking resistance compared to the examples. In Comparative Examples 2 and 4, good results were obtained in the ISOT test, but in the FALEX seizure test, the seizure resistance was inferior to that in Examples.
Comparative Example 3 contains a hydroxyl group-containing PMA and a conventional PMA that does not contain a hydroxyl group, but does not contain ZnDTP, and instead contains an SP-based additive. In the FALEX image sticking test, 793.8 kg (= 1750 pounds), which shows a certain result in the seizure resistance, but does not give a good result in the oxidation stability in the ISOT test.
In the FZG pitching test, Comparative Example 1 is 42 hours, but Comparative Examples 2 and 4 have a fatigue life of 30 to 32 hours. In Comparative Example 3, since the result of the ISOT test was bad, the FZG pitching test was omitted.
The commercially available transmission oil of Comparative Example 5 has poor results in the SONIC test, and good results have not been obtained in the FALEX seizure test and FZG pitching test.

Claims (6)

A mineral oil and / or synthetic oil base oil containing a hydroxyl group-containing poly (meth) acrylate and a hydroxyl group-free poly (meth) acrylate and zinc dithiophosphate, the hydroxyl group-containing poly (meth) The mass ratio of acrylate to poly (meth) acrylate containing no hydroxyl group is 83. 3:16. 7 to 40:60, the FALEX seizure test result of the composition is 907.2 Kg (2000 lbs) or more, the ISOT test (kinematic viscosity increase rate at 40 ° C. and 100 ° C.) is 8% or less, FZG A lubricating oil composition for transmission oils having a pitching test result of 48 hours or more.   The mass average molecular weight of the poly (meth) acrylate containing a hydroxyl group is 5,000 to 50,000, and the mass average molecular weight of a poly (meth) acrylate not containing a hydroxyl group is 20,000 to 100,000. The lubricating oil composition for transmission oil according to claim 1, wherein   The lubricating oil composition for transmission oil according to claim 1 or 2, further comprising a dihydrocarbylcarbamic acid derivative.   The lubricating oil composition for transmission oil according to claim 3, wherein the dihydrocarbyl carbamic acid derivative is a dihydrocarbyl carbamic acid aliphatic ester or a dihydrocarbyl carbamic acid metal salt.   The lubricating oil composition for transmission oil according to claim 4, wherein the metal salt of dihydrocarbylcarbamate is zinc dihydrocarbylcarbamate or molybdenum dihydrocarbylcarbamate. The base oil, 100 ° C. kinematic viscosity of ^{2mm 2} / ^s~8mm 2 / s, the transmission oil for lubricating oil according to claim 1, viscosity index is characterized by a 90 to 250 Composition.