JP2010248284A - Lubricating oil composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricating oil composition for use in wet brakes, which has excellent wet brake friction characteristics, wear resistance, and oxidative stability and is suitable as a general-purpose lubricating oil for an agricultural tractor or a construction machinery vehicle. <P>SOLUTION: The lubricating oil composition for use in wet brakes comprises: (A) 0.01 to 0.5 mass%, based on the total weight of the composition, of a diol compound represented by formula: C<SB>n</SB>H<SB>2n+2</SB>O<SB>2</SB>or C<SB>n</SB>H<SB>2n</SB>O<SB>2</SB>(formula 1), wherein the number of carbon atoms n is from 10 to 24; and (B) 0.05 to 5 mass%, based on the total weight of the composition, of a phosphorus compound represented by formula: (RO)<SB>2</SB>PH=O (formula 2), wherein R is a 14-18C alkyl or alkenyl group, with a mineral oil and a synthetic oil as base oils, wherein the ratio of μ3/μ38 at 40°C in a micro-clutch test is 0.8 or less. The lubricating oil composition for use in wet brakes meets the ratio of μ3/μ38 ranging from 0.7 to 0.8. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lubricating oil composition for a wet brake suitable as a common lubricating oil for agricultural tractors and construction machinery vehicles having excellent wet brake friction characteristics, wear resistance and oxidation stability.

  Agricultural tractor wet braking systems require braking performance commensurate with pedaling force, but at the same time, the friction part is also required to prevent abnormal noise and abnormal vibration caused by sliding. Specifically, a higher coefficient of static friction is preferable for braking performance, but it is likely to cause squeal and abnormal vibration due to a stick-slip phenomenon immediately before stopping. Therefore, if the friction coefficient is increased when the sliding speed is high, such as at the start of braking, and the static friction coefficient is low when the braking speed is low, good brake stop performance and stick-slip resistance can be achieved. It will be compatible.

  If the friction characteristics are classified in this way, the dynamic friction coefficient is high in order to achieve both good brake stop performance and stick-slip resistance, and if the static friction coefficient is low, the value of μs / μd becomes small. If the stick-slip resistance is poor, the dynamic friction coefficient is low, the static friction coefficient is high, and the value of μs / μd is large.

  In general, a friction modifier (FM) is blended in order to impart necessary friction characteristics to the lubricating oil for wet clutches and wet brakes. As the friction modifier, fatty acids, ester compounds, alcohol compounds, amine compounds, amide compounds, phosphorus compounds, sulfur compounds, solid lubricants, and the like are used.

  The friction modifier adsorbs on the surface of the brake material or clutch material to form an adsorbed film, and the frictional resistance / peeling resistance between the films becomes the frictional force. If the adsorbing force is large, the frictional force increases. . On the other hand, if the attractive force is small, the frictional force becomes small as a result of being easily peeled off. The wet friction characteristic determines how much the adsorption force changes depending on whether the sliding speed is large or small, and is related to the dynamic friction coefficient and the static friction coefficient.

  Fatty acids have excellent adsorption properties, but have poor thermal oxidation stability and poor water separation. The blending of other ester compounds, alcohol compounds, and amide compounds differs in lipophilicity and adsorption power depending on the structure of each compound. That is, ester compounds have a problem of hydrolyzability when mixed with water, amine compounds are likely to generate lacquer at high temperatures, and alcohol compounds are weak in lipophilicity as FM. Has a point.

  Examples of the wet brake lubricant composition include Patent Document 1 and Patent Document 2, but the former includes acidic phosphate ester amine salt, oleic acid, oleic acid diethanolamide, oleic acid triglyceride and stearyl alcohol as friction modifiers. On the other hand, in the latter, ethers and phosphate compounds of higher alcohols having 8 or more carbon atoms and glycerin are introduced. In Patent Document 3, a combination of diol and phosphate is introduced as a friction modifier.

Japanese Patent Laid-Open No. 6-200269 JP 2004-204002 A Japanese Patent No. 4132280

  As described above, the present invention, for example, an agricultural tractor having a friction characteristic that increases the dynamic friction coefficient when the sliding speed is high, such as when the brake is applied, and has a low static friction coefficient when the speed at which the brake stops is low. It is an object of the present invention to provide a lubricating oil composition that is effective in wet braking systems for large vehicles such as the above and has both brake stop performance and stick-slip resistance.

The first of the present invention is a wet type containing a mineral oil and a synthetic oil as a base oil and (A) 0.01 to 0.5% by mass of a diol compound represented by the following general formula (formula 1) based on the total amount of the composition The present invention relates to a lubricating oil composition for brakes.
C _n H _2n + _{2 O} 2 or _C n _H 2n _{O 2} (Formula 1)
(The carbon number n is 10 to 24)
The second of the present invention uses mineral oil and synthetic oil as a base oil, and (A) a diol compound represented by the following general formula (formula 1) is 0.01 to 0.3% by mass based on the total amount of the composition, and (B ) The phosphorus compound represented by the general formula (Formula 2) is contained in an amount of 0.05 to 5% by mass based on the total amount of the composition, and the ratio of μs / μd (μ3 / μ38) at 40 ° C. in the microclutch test is 0.8. The present invention relates to the following lubricating oil composition for wet brakes.
C _n H _2n + _{2 O} 2 or _C n _H 2n _{O 2} (Formula 1)
(The carbon number n is 10 to 24)
(RO) ₂ PH = O (Formula 2)
(R is an alkyl or alkenyl group having 14 to 18 carbon atoms)
According to a third aspect of the present invention, the lubricating oil composition for wet brakes of claims 1 and 2 is further added to a metal detergent dispersant, an ashless dispersant, a zinc dialkyldithiophosphate, a hindered phenol antioxidant, and an amine antioxidant. The present invention relates to a composition containing at least one agent, a sarcosine rust inhibitor, a polymethacrylate viscosity improver and a silicone antifoaming agent.

  An object of the present invention is to provide a lubricating oil composition which is effective as a lubricant for a wet brake system for a large vehicle such as an agricultural tractor and has both improved brake stop performance and stick-slip resistance.

  The present invention relates to the improvement of the prior art as described above, and as a result of earnest research to overcome the problems of alcohol compound friction modifiers, alcohol compound friction modifiers having a special structure and In combination with a specific phosphate ester, the ratio of the friction coefficient of 3 mm / s to the friction coefficient of 38 mm / s, that is, the ratio of μ3 / μ38 at 40 ° C. is 0.8 or less, preferably 0.5 -0.8, more preferably 0.6-0.8, it has been found that it has not only brake performance but also excellent stick-slip resistance, and a lubricating oil composition for wet brakes using this I came to discover things.

  The composition of the present invention will be described in detail. One preferred embodiment thereof is a mineral lubricating oil having a viscosity of about 1 to 50 cSt at 100 ° C. or a refined product thereof (hereinafter referred to as “mineral oil”) and a viscosity of about 100 ° C. 0.01 to 0.5% by mass, preferably about 0.05 to 0%, of the alcohol component (A) represented by the formula 1 with respect to the lubricating base oil selected from 1 to 50 cSt synthetic lubricating oil base materials. .3% by mass blended with mineral oil or hydrocarbon synthetic oil. If it is less than this, the original effect will not be exhibited, while if it is more, the solubility in oil may be problematic. In order to increase the solubility, the addition amount can be further increased by adding a small amount of ester or the like. Moreover, since it is not necessary to completely dissolve in the base oil for applications such as grease, the amount added can be further increased.

C _n H _{2n + 2} O ₂ or C _n H _2n O ₂ (the carbon number n is 10 to 24) (Formula 1)

Specifically, the aliphatic alcohol component is a diol having 8 to 18 carbon atoms, more preferably 12 to 16 carbon atoms, and two OH groups. More preferably, the OH group is an aliphatic 1,2-diol, that is, an OH group bonded to positions 1 and 2 of the aliphatic carbon. The aliphatic part may be either an alkyl group or an alkenyl group.
The following compounds can be listed as exemplary compounds.
1,2-decanediol, 1,2-undecanediol, 1,2-dodecanediol, 1,2-tridecanediol, 1,2-tetradecane as OH groups bonded to the 1- and 2-positions Diol, 1,2-pentadecanediol, 1,2-hexadecanediol, 1,2-heptadecanediol, 1,2-octadecanediol, 1,2-nonadecanediol, 1,2-icosanediol, 1,2, -Henicosanediol, 1,2-docosanediol, 1,2-tricosanediol, 1,2-tetracosanediol.

And it is preferable to contain 0.05-5 mass% of phosphorus compounds (B) shown by Formula 2 on the basis of the total amount of the composition.
(RO) ₂ PH = O (Formula 2)
(R is an alkyl or alkenyl group having 12 to 18 carbon atoms)
Particularly preferred are dialkyl hydrogen phosphites or dialkenyl hydrogen phosphites. This hydrogen phosphite has a characteristic that it does not impair the oxidative stability of the lubricating oil because it is less acidic than the acidic phosphate ester. Specifically, for example, di-n-dodecyl hydrogen phosphite (dilauryl hydrogen phosphite), di-n-tetradecyl hydrogen phosphite (dimyristyl hydrogen phosphite), di-n-hexadecyl hydro Gen phosphite (dipalmityl hydrogen phosphite), di-n-octadecyl hydrogen phosphite (distearyl hydrogen phosphite), di-9-octadecenyl hydrogen phosphite (dioleoyl hydrogen phosphite) ), Diesters such as di-n-icosenyl hydrogen phosphite, n-dodecyl hydrogen phosphite (lauryl hydrogen phosphite), n-tetradecyl hydrogen phosphite (myristyl hydrogen phosphite) Phosphite), n-hexadecyl hydrogen phosphite (palmityl hydrogen phosphite), n-octadecyl hydrogen phosphite (stearyl hydrogen phosphite), 9-octadecenyl hydrogen phosphite (oleyl hydrogen phosphite) Phyto), n-icosenyl hydrogen phosphite and the like are preferable, and dioleyl hydrogen phosphite is most preferable.

  If both of the above components (A) and (B) are too small, the effect of addition will not be sufficiently exhibited, and if the amount is too large, improvement of the effect cannot be expected, which is disadvantageous because of high costs. . They discovered that performance can be improved synergistically by combining them, not alone.

  In addition to the above components (A) and (B), the lubricating oil composition of the present invention includes known additives that are usually used according to the purpose, such as metal detergent dispersants, ashless dispersants, and seizures. Antiwear agents, antioxidants, corrosion inhibitors, viscosity index improvers, pour point depressants, antifoaming agents and the like are blended.

As the mineral base oil of the present invention, specifically, a lubricating oil fraction obtained by distillation under reduced pressure of atmospheric residual oil obtained by atmospheric distillation of crude oil, solvent removal, solvent extraction, hydrogen This is a method of isomerizing GTL WAX (gas to liquid wax) produced by one or more treatments such as cracking, solvent dewaxing, hydrorefining, etc., or wax isomerized mineral oil, Fischer-Tropsch process, etc. Examples of the lubricant base oil to be manufactured can be given.
Synthetic oils include, for example, poly α-olefin (PAO), α-olefin copolymer, polybutene, alkylbenzene, polyol ester, dibasic acid ester, polyoxyalkylene glycol, polyoxyalkylene glycol ester, polyoxyalkylene glycol ether. , Hindered esters, silicone oils and the like. As described above, these synthetic oils can be used alone or in combination of two or more, and further, mineral oil and synthetic oil can be used in combination.

  Examples of metal detergent dispersants include alkaline earth metal sulfonates and alkaline earth metal phenates. Examples of ashless dispersants include alkenyl succinimides, alkenyl succinates, amides of long-chain fatty acids and polyamines (aminoamide type), and the like. However, seizure wear inhibitors include sulfurized fats and oils, sulfurized olefins, sulfides, phosphate esters, phosphite esters, thiophosphate esters, etc., and antioxidants such as amine and phenolic antioxidants are corrosive. Examples of the inhibitor include benzotriazole and alkenyl succinate, polymethacrylate and olefin copolymer as the viscosity index improver, polymethacrylate as the pour point depressant, silicon compound as the antifoaming agent, Examples thereof include ester-based antifoaming agents.

The wet friction characteristics were evaluated in accordance with the friction test method (JCMAS P 0474) using a micro-clutch tester of the Japan Construction Mechanization Association / Hydraulic hydraulic fluid for construction machinery-Friction characteristics test method (JCMAS P 047: 2004). Was done.
The detailed test method of the micro clutch test is shown below.
[Specimen material]
Clutch disc facing material: D-0512 (JASO M349 material)
Plate material: SS400
[Test conditions]
Temperature: 40 and 80 ° C
Surface pressure: 1MPa
Sliding speed: 3.0 and 38.0 mm / s
Friction time: 5 min
Hereinafter, the present invention will be described by way of examples and comparative examples under the above microclutch test conditions, but these are merely examples, and the present invention is not limited by these.

[Examples 1-7 and Comparative Examples 1-5]
Examples and comparative examples of the present invention include commercially available tractor oil comparative example 1 (including overbased calcium sulfonate, zinc di-2-ethylhexyl dithiophosphate, triphenyl phosphite, polybutenyl succinimide, succinate) Example 4, Comparative Example 1 and Comparative Example, in which 0.2% by mass of each of alcohol compounds 1, 2 and 3 was added to the package additive), and Examples 2 and 3 and Example 2 were further combined with a phosphorus compound. Comparative Examples 2, 3, 4, 5 in which 0.2% by mass of alcohol compounds 4, 5, 6, and 7 were added to 1 respectively, and 0.1% by mass and 0.3% by mass of alcohol compound 2 in Comparative Example 1 A prototype Example 7 was prepared by combining the added Examples 5 and 6 and Example 6 with 0.2% by mass of a phosphorus compound. The components and properties of Comparative Example 1 are shown in Table 1, and the formulations of Examples and Comparative Examples are shown in Table 2 and Table 3.

(A) Alcohol compound and (B) Phosphorus compound used in Examples and Comparative Examples Alcohol compound 1: 1,2-tetra / hexadecanediol mixed Alcohol compound 2: 1,2-hexadecanediol Alcohol compound 3: 1, 2- Dodecanediol Alcohol compound 4: 1-Hexadecanol Alcohol compound 5: 1-Dodecanol Alcohol compound 6: 1-Octanol Alcohol compound 7: 1,2-Octanediol Phosphorus compound: Dioleyl hydrogen phosphite

ここで比較例１の市販トラクターオイルは、過塩基性カルシウムスルホネート、ジ−２−エチルヘキシルジチオリン酸亜鉛、トリフェニルホスファイト、ポリブテニルコハク酸イミド、コハク酸エステルが含まれるパッケージ添加剤６質量％とポリメタアクリレート系の粘度指数向上剤６質量％を基油（鉱油系基油、動粘度が５．９５ｍｍ^２／ｓ ＠１００℃ および３７．５ｍｍ^２／ｓ ＠４０℃）に添加して調整したもので、さらにポリメタアクリレート系の流動点降下剤を外割で０．１質量％および泡立ち防止剤としてシリコーン系消泡剤を１０ｐｐｍ添加している。 Comparative Example 1 Commercial Tractor Oil Properties and Its Constituents

Here, the commercial tractor oil of Comparative Example 1 is an overbased calcium sulfonate, zinc di-2-ethylhexyl dithiophosphate, triphenyl phosphite, polybutenyl succinimide, and succinic acid ester containing 6% by mass of a package additive. And 6% by mass of polymethacrylate viscosity index improver added to base oil (mineral oil base oil, kinematic viscosities 5.95mm ² / s @ 100 ° C and 37.5mm ² / s @ 40 ° C) In addition, 0.1% by mass of a polymethacrylate-based pour point depressant and 10 ppm of a silicone-based antifoaming agent as an antifoaming agent were added.

Example formulation

Formulation of comparative example

比較例のマイクロクラッチ試験測定結果

About the Example and comparative example which were made as an experiment, the sliding speed measured the friction coefficient of 3 mm / s and 38 mm / s at the oil temperature of 40 degreeC and 80 degreeC. The results are shown in Tables 4 and 5.
Example microclutch test measurement results

Microclutch test measurement results of comparative example

Looking at the test results at 40 ° C., Comparative Example 1 is a commercial tractor oil, but the friction coefficient μs (3 mm / s) is 0.108, whereas μd (38 mm / s) is 0.117, and μs / μd. The ratio of 0.923 was 0.923, but when the mixed diol of C14 and C16 of Example 1 was added, μs was 0.082, μd was 0.113, and the ratio of μs / μd was as low as 0.726. It becomes low and it has shown that the anti-stick slip in a wet clutch is suppressed. Further, the ratio of C16 1,2-hexadecanediol is 0.741 and the C12 dodecanediol is 0.739, both of which are low and give good friction properties. Certain C16 1-hexadecanol has a ratio of μs / μd of 0.862, 1-dodecanol of 0.802 and 1-octanediol of 0.808, which is lower than the commercial tractor oil of Comparative Example 1 μs / μd. However, the ratio of μs / μd was higher than that of the example, and the excellent friction characteristics of the diol of the example were shown.
Similarly, considering the results at 80 ° C., the ratios of μs / μd in Examples 1, 2, and 3 were 0.694, 0.692, and 0.692, respectively, whereas Comparative Examples 1, 2, 3, 4 The μs / μd ratio of 5 was 0.731, 0.764, 0.736, 0.716, and 0.704, and the example clearly showed excellent friction characteristics as at 40 ° C.
Further, as in Example 4, when the μs / μd ratio at 80 ° C. is 0.659 and diol and dioleyl hydrogen phosphite are combined, the friction characteristics are further improved.

  Furthermore, in Examples 5 and 6, the addition amount of 1,2-hexadecanediol was added at 0.1 and 0.3% by mass, and the friction behavior was checked. At the same time, in Example 7 in which 0.2% by mass of dioleyl hydrogen phosphite was added to Example 6, the friction characteristics could be further improved.

Claims (3)

A lubricating oil composition for wet brakes which contains mineral oil and synthetic oil as a base oil and (A) 0.01 to 0.5 mass% of a diol compound represented by the following general formula (formula 1) based on the total amount of the composition.
C _n H _2n + _{2 O} 2 or _C n _H 2n _{O 2} (Formula 1)
(The carbon number n is 10 to 24) Mineral oil and synthetic oil as a base oil, (A) 0.01 to 0.3% by mass of a diol compound represented by the following general formula (formula 1) based on the total amount of the composition, and (B) general formula (formula 2) A lubricating oil composition for wet brakes containing 0.05 to 5% by mass of the phosphorus compound represented by formula (1) based on the total amount of the composition, and the ratio of μ3 / μ38 at 40 ° C. in the microclutch test is 0.8 or less.
C _n H _2n + _{2 O} 2 or _C n _H 2n _{O 2} (Formula 1)
(The carbon number n is 10 to 24)
(RO) ₂ PH = O (Formula 2)
(R is an alkyl or alkenyl group having 14 to 18 carbon atoms) 3. The wet brake lubricating oil composition according to claim 1 and 2, further comprising a metal detergent dispersant, an ashless dispersant, a zinc dialkyldithiophosphate, a hindered phenol antioxidant, an amine antioxidant, and a sarcosine rust inhibitor. A composition comprising at least one polymethacrylate viscosity improver and a silicone antifoaming agent.