JPH0587115B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a fluid composition for traction drives, and more particularly to a fluid composition for traction drives that has excellent traction coefficients and high-temperature properties. BACKGROUND TECHNOLOGY In the power transmission section of a traction drive device such as a ball & cone type, cone & ring type, wheel & disc type, chain & sheave type, toroidal type, or planetary roller type, the rolling contact surface Since power is transmitted using the rolling friction created by the hardening of the lubricating oil film, the lubricant used there, that is, the traction drive fluid, must have excellent power transmission ability, that is, a high traction coefficient. is required. At the same time, since the traction drive fluid is exposed to extremely high temperature conditions when the traction drive device operates at high speed, it is necessary to have high temperature characteristics to be able to form an oil film on the friction surface even under high temperature conditions.
That is, it is required to have a small amount of evaporation loss at high temperatures and a certain level of viscosity even at high temperatures. Conventionally, regarding traction drive fluid, for example, Japanese Patent Publication No. 46-338, No. 46-339,
No. 47-7664, No. 48-29715, No. 48-42067,
No. 48-42068, No. 53-36105, No. 58-12319,
No. 58-27838, No. 60-1353, No. 60-1354,
Various compounds have been proposed in Patents No. 60-19951, No. 60-43391, No. 60-43392, and many other patents and documents. Problems to be Solved by the Invention However, the known traction drive fluids listed above have not been put into practical use due to reasons such as difficulty in obtaining raw materials, complicated manufacturing methods, and unsuitable traction coefficients for practical use. 2,4-dicyclohexyl-2-methylpentane, which was proposed in Japanese Patent Publications No. 53-36105 and No. 58-12319, is considered to be practical, and may be used as a fluid as it is or be expanded to this. It is only used as a grease by blending it with an agent. However, although this 2,4-zylclohexyl-2-methylpentane has an excellent traction coefficient, it has the drawbacks of high evaporation loss and low viscosity under high temperature conditions. The present inventors have conducted extensive research to overcome the drawbacks of the conventionally known traction drive fluids as described above, and as a result, a composition containing compounds having specified structures and properties in a specific ratio has been developed. The present inventors have discovered that this fluid has excellent performance as a drive fluid, and have completed the present invention. An object of the present invention is to provide a fluid composition for a traction drive that has a high traction coefficient and excellent high-temperature properties, that is, has low evaporation loss under high-temperature conditions and excellent viscosity properties. Means for Solving the Problems The present invention provides one or more ester compounds selected from the group consisting of () (A) diesters, and (B) polyol esters, and has a kinematic viscosity of 2 at 40°C. ~
40cSt, 20-80% by weight, and () general formula

[Formula, n represents an integer of 0 or 1, R ₁ and R ₂ are R ₂ = CH 3 when R 1 = H, and R ₂ = CH ₃ when R ₁ = CH ₃
Each group represents a group in which R ₂ =H. The present invention provides a fluid composition for a traction drive, characterized in that it is made by mixing 80 to 20% by weight of polycyclohexyl alkane represented by: Hereinafter, the content of the present invention will be explained in more detail. The component () in the present invention is one or more ester compounds selected from the group consisting of (A) diester and (B) polyol ester,
The kinematic viscosity at 40°C is 2 to 40 cSt. As (A) diester and (B) polyol ester used as component () of the present invention, any one can be used as long as it satisfies the above characteristics, but specifically, for example, the following can be used. Such compounds are preferably used. That is, as (A) diester, the general formula

A compound represented by the following formula is desirable. In the above formula, R ₃ represents a divalent hydrocarbon group having 4 to 12 carbon atoms, preferably 4 to 10 carbon atoms, preferably an alkylene group, and R ₄ and R ₅ may be the same or different, and each represents a carbon atom. It represents an alkyl group having a number of 6 to 16, preferably 8 to 13. In particular, as R ₃ , the general formula (-CH ₂ )- _n
A linear alkylene group represented by (m is an integer of 4 to 10) is preferred. Among the diesters represented by the above formula, particularly preferred as component () of the present invention are, for example, di-2-ethylhexyl adipate, di-2-ethylhexyl azelate, and di-2-ethylhexyl azelate.
2-ethylhexyl sebacate, di-2-ethylhexyl dodecanoate, diisooctyl adipate, diisooctyl azelate, diisooctyl sebacate, diisooctyl dodecanoate,
Examples include diisodecyl adipate, diisodecyl azelate, diisodecyl sebacate, diisodecyl dodecanoate, ditridecyl adipate, ditridecyl azelate, ditridecyl sebacate, ditridecyl dodecanoate, and mixtures thereof. On the other hand, (B) polyol ester has the general formula

A compound represented by the following formula is desirable. In the above formula, a and b are 0≦a≦2, 2≦b≦4, respectively,
And it shows an integer such that a+b=4. Also
R ₆ is an alkyl group having 1 to 4 carbon atoms, preferably a methyl group or an ethyl group, R ₇ is an alkyl group having 2 to 17 carbon atoms,
Preferably each represents 2 to 12 alkyl groups. Specifically, as the polyol ester, an ester of a polyol in which the β carbon (second carbon) on the alcohol side of the ester bond is a tertiary carbon and an aliphatic monocarboxylic acid having 3 to 13 carbon atoms is particularly preferred. Specific examples of this polyol include neopentyl glycol, trimethylolethane, trimethylolpropane, pentaerythritol, and mixtures thereof, while aliphatic monocarboxylic acids include those having 3 to 13 carbon atoms.
Straight-chain or branched aliphatic monocarboxylic acids, specifically straight-chain fatty acids such as butanoic acid, caproic acid, caprylic acid, capric acid, and uralic acid obtained by decomposing fats and oils, and synthetically obtained Examples include straight-chain C ₇ C ₉ acids, branched acids, neopentyl-type branched acids, and mixtures thereof. Furthermore, as the component () of the present invention, the above-mentioned
An ester mixture obtained by mixing (A) diester and (B) polyol ester in any ratio can also be used. In addition, the ester used as component () of the present invention has a viscosity of 2 to 40 cSt at 40°C, and also has a pour point of -30°C or lower, preferably -40°C or lower. is desirable. On the other hand, the component () as used in the present invention refers to the general formula

It is a polycyclohexyl alkane represented by In the above formula, n represents an integer of 0 or 1, and R ₁
and R ₂ represent a group in which R ₂ =CH ₃ when R ₁ =H, and R ₂ =H when R ₁ =CH ₃ . This component (), polycyclohexylalkane, is produced by, for example, polymerizing α-methylstyrene or thermally decomposing poly-α-methylstyrene to obtain triphenylalkane or tetraphenylalkane. It can be produced by nuclear hydrogenation. Specifically, for example, the polymerization of α-methylstyrene uses a solid acid catalyst such as acid clay, activated clay, silica-alumina, montmolinite-type viscosity, or silica gel, and an oxygen-containing catalyst such as water, dihydric alcohol, or ether. This reaction can be easily carried out by using a compound as a reaction regulator and reacting α-methylstyrene under heating. In addition, the nuclear hydrogenation reaction uses a nuclear hydrogenation catalyst such as nickel, nickel-diatomaceous earth, Raney nickel, platinum, platinum-alumina, rhodium, rhodium-alumina, etc. This can be easily done by contacting with. Depending on the conditions, the polycyclohexylalkane obtained by the above method may have a structure other than the component () of the present invention (dicyclohexylalkane,
Pentacyclohexylalkanes, cyclic compounds, etc.) may also be mixed in as by-products, so if necessary, the target compound can be extracted by separation operations such as distillation. In the traction drive fluid composition of the present invention, the mixing ratio of components () and () is as follows:
The proportion of component () is 80 to 20% by weight, preferably 70 to 30% by weight, relative to 20 to 80% by weight, preferably 30 to 70% by weight of component (). If the mixing ratio of component () is less than the above range, the viscosity of the composition becomes too high, and in particular, component () alone is semi-solid at room temperature and cannot be put to practical use. On the other hand, if the mixing ratio of component () exceeds the above range, the high temperature properties and traction coefficient of the composition will decrease, which is not preferable. In the present invention, a traction drive fluid with excellent various performances can be obtained by mixing the above-mentioned components () and () in a specific ratio.
It may also contain 4-dicyclohexyl-2-methylpentane. The content of this 2,4-dicyclohexyl-2-methylpentane is arbitrary, but is usually at most 100 parts by weight, preferably at most 50 parts by weight, based on 100 parts by weight of the polycyclohexylalkane (). When this 2,4-dicyclohexyl-2-methylpentane is used in combination, the components () and () of the present invention are mixed to obtain the fluid composition for traction drive according to the present invention, and then 2,4-dicyclohexyl-2-methylpentane is used. -dicyclohexyl-2
- Methylpentane may be mixed. Furthermore, as mentioned above, when producing component () by polymerizing α-methylstyrene, depending on the reaction conditions, in addition to component (), 2,4-dicyclohexyl-2
-Because methylpentane is also produced as a by-product, the by-produced 2,
4-dicyclohexyl-2-methylpentane may be mixed with component () in the form of a mixture with component () without being separated and removed. Furthermore, as mentioned above, when producing component () by polymerizing α-methylstyrene, depending on the reaction conditions, a cyclic compound (α-
Nuclear hydrogenation products of cyclic dimers, cyclic trimers and cyclic tetramers of methylstyrene may also be produced as by-products, but these cyclic compounds may also be used in the present invention to the extent that they do not impair the effects of the present invention. It may be included in the traction drive fluid composition. Furthermore, various commonly used lubricating oil additives can be added to the traction drive fluid composition of the present invention, if necessary. Specifically, for example, hinted phenols such as 2,6-di-t-butyl-p-cresol, aromatic amines such as phenyl-α-naphthylamine, organometallic compounds such as zinc dialkyldithiophosphate, sulfides, and disulfides. Antioxidants such as sulfur compounds such as carboxylic acids, sulfonic acids, phosphates, amines, alcohols, rust inhibitors such as esters, organic sulfur compounds, organic halogen compounds,
Organic metal salts such as zinc dialkyldithiophosphate, molybdenum dialkyldithiophosphate, and molybdenum dialkyldithiocarbamate, extreme pressure agents such as phosphate esters, polymethacrylate,
Viscosity index improvers such as polyisobutylene, antifoaming agents such as silicone oil, etc. can be added. Although the amount of these known lubricating oil additives added is arbitrary, it is usually desirable to add them so that the total amount added is 20% by weight or less, preferably 10% by weight or less, based on the total amount of the composition. . Furthermore, known organic or inorganic thickeners for greases, specifically soap-based thickeners such as lithium soap, sodium soap, calcium soap, lithium complex soap, calcium complex soap, Complex soap thickeners such as aluminum complex soaps, non-soap thickeners such as organic siloxanes, terephthalamates, polyureas, organically treated clays, and silica aerogels can be added to the traction drive fluid composition of the present invention. It can also be used as a traction grease. The amount of thickening agent mixed when used as a traction grease is arbitrary, but the content of thickening agent is usually 1 to 1% based on the total amount of the grease composition.
It is preferable to mix it so that it is 30% by weight, preferably 3 to 20% by weight. EXAMPLES OF THE INVENTION The contents of the present invention will now be explained in more detail with reference to Examples and Comparative Examples. Examples 1 to 3 and Comparative Examples 1 to 4 Traction drive fluid compositions (Examples 1 to 4) according to the present invention were obtained with the compositions shown in Table 1. In addition, each component shown in Table 1 has the following properties. () Ingredient diester; diisooctyl sebacate. Kinematic viscosity 11.5cSt
(@40℃), pour point -60℃ or less, flash point 222℃. Polyol ester 1; trimethylolpropane tricaprylate. Kinematic viscosity 28.2cSt, pour point -50℃, flash point 209℃. Polyol ester 2: Tetraester of pentaerythritol and linear C ₆ to _{C 10} mixed fatty acid. Kinematic viscosity 3.5cSt (@40℃), pour point -48℃, flash point 257℃. () Component polycyclohexylalkane: A distillate with a boiling point of 415 to 430°C (converted to normal pressure) obtained by nuclear hydrogenation of a product obtained by polymerizing α-methylstyrene using activated clay as a catalyst using a nickel catalyst, and then distilling the product. minutes, is semi-solid at room temperature (20℃),

[Chemical formula] (R ₁ = CH ₃ , R ₂ = H or R ₁ = H, R ₂ = CH ₃ as the main component (content 95% by weight). Regarding the compositions of Examples 1 to 3, the following is A performance evaluation test was conducted, and the results are also shown in Table 1. Performance evaluation test [High temperature viscosity] The kinematic viscosity at 100°C was measured according to the kinematic viscosity test method specified in JIS K 2283.3. [Evaporation loss amount ] After heating at 120°C for 100 hours according to the lubricating oil thermal stability test method specified in JIS K 2540, the evaporation loss (weight loss) of the oil was determined in weight %. [Traction coefficient] Four-cylinder rolling friction test using a machine, 1500rpm,
Measurements were made under the conditions of a load of 92.5 Kg/mm ² and a slip ratio of 2%. For comparison, the case where only component () was used (Comparative Examples 1 to 3) and the case where 2,4-dicyclohexyl-2-methylpentane, which is widely used as a traction drive fluid, were used (Comparative Example 4). ) was also subjected to the above performance evaluation test,
The results are also listed in Table 1.

【table】

[Table] Effects of the Invention As is clear from the comparison of the performance evaluation tests of Examples in Table 1 and Comparative Examples 1 to 3, the high-temperature properties are significantly improved by blending component () compared to when component () is used alone. (increased viscosity at high temperatures and reduced evaporation loss) and also improved the traction coefficient. Component (), which cannot be put to practical use alone, works extremely effectively as a combination agent of component (). I know what you're doing. Furthermore, the compositions of Examples according to the present invention have particularly excellent high-temperature properties compared to 2,4-dicyclohexyl-2-methylpentane of Comparative Example 4, which is generally used as a traction drive fluid. Useful as a shock drive fluid.

Claims (1)

[Scope of Claims] 1 () One or more ester compounds selected from the group consisting of (A) diesters, and (B) polyol esters, having a kinematic viscosity of 2 to 2 at 40°C.
40 cSt, 20 _{to 80} % by weight _{, and} () general _formula When R ₁ = CH ₃
Each group represents a group in which R ₂ =H. ) A fluid composition for a traction drive, characterized in that it is made by mixing 80 to 20% by weight of a polycyclohexyl alkane represented by: