JP2014185289A - Hydraulic oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic oil composition capable of securing both of prevention of inner leakage and reduction of piping resistance and high in energy efficiency of whole hydraulic system.SOLUTION: There is provided a hydraulic oil composition containing a lubricant base oil and at least one kind of copolymer selected from an olefine copolymer having a number average molecular weight of 18000 or less of 0.2 to 40 mass% based on the total amount of the composition and a copolymer of α olefine and dicarboxylic acid ester having the number average molecular weight of 20000 or less.

Description

  The present invention relates to a hydraulic fluid composition. Specifically, the present invention relates to a hydraulic energy composition having high energy efficiency and containing a viscosity index improver.

  In recent years, energy-saving hydraulic fluid has been developed as one of the countermeasures against global warming. As a conventional energy-saving hydraulic fluid, for example, there is one in which energy consumption at the start-up of the apparatus is reduced by lowering the low temperature viscosity.

  In addition, energy-saving hydraulic fluids have been developed that contain a viscosity index improver to reduce energy consumption during steady operation after the change in viscosity of the hydraulic fluid is reduced and the oil temperature is increased. This energy-saving hydraulic fluid prevents oil leakage (internal leakage) from inside various hydraulic equipment unique to construction machinery by reducing the change in viscosity of the hydraulic fluid (higher viscosity index), thereby reducing energy consumption. (For example, refer to Patent Documents 1 to 3).

JP 2005-307197 A JP 2011-046900 A JP 2012-180535 A

  However, in the case of the energy-saving hydraulic hydraulic fluid as described in Patent Documents 1 to 3 above, loss due to pipe resistance increases due to the higher viscosity index of the hydraulic fluid. Therefore, even if energy consumption can be reduced by preventing internal leakage, there is still room for improvement in terms of improving the energy efficiency of the entire hydraulic system.

  The present invention has been made in view of such circumstances, and a hydraulic fluid composition that can achieve both internal leakage prevention and pipe resistance reduction, and can improve the energy efficiency of the entire hydraulic system. The purpose is to provide.

  As a result of intensive studies, the inventors of the present invention have found that a hydraulic fluid composition in which a specific amount of a specific copolymer is blended with a lubricating base oil is excellent for both preventing internal leakage of hydraulic systems and reducing pipe resistance. The present inventors have found that it has viscosity characteristics and have completed the present invention.

  That is, the present invention relates to a lubricating base oil, an olefin copolymer having a number average molecular weight of 20,000 or less and an α-olefin having a number average molecular weight of 20,000 or less, based on the total amount of the composition. There is provided a hydraulic fluid composition containing at least one copolymer selected from copolymers with dicarboxylic acid esters.

The hydraulic fluid composition has a viscosity index of 155 or more, (A) kinematic viscosity at 80 ° C. (unit: mm ² / s), and (B) shear viscosity at 80 ° C. (unit: mPa · s). s, shearing condition: 10 ⁶ / s) (A / B) is preferably 1.3 or less.

  The hydraulic fluid composition of the present invention has a low kinematic viscosity with respect to a high shear viscosity, can achieve both internal leakage prevention and pipe resistance reduction, and can improve the energy efficiency of the entire hydraulic system. It has a great effect.

  Hereinafter, preferred embodiments of the present invention will be described.

  A hydraulic fluid composition according to an embodiment of the present invention includes a lubricant base oil, an olefin copolymer having a number average molecular weight of 20,000 or less, and an α olefin having a number average molecular weight of 20,000 or less and a dicarboxylic acid ester. Contains at least one selected from polymers.

  Examples of the lubricating base oil used in the present embodiment include mineral oil, synthetic hydrocarbon oil, synthetic oxygenated oil, and fat. These lubricating base oils can be used singly or in combination of two or more.

  The mineral oil is not particularly limited. For example, a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation and vacuum distillation can be subjected to solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, contact Paraffinic mineral oil or naphthenic mineral oil refined by appropriately combining purification treatments such as dewaxing, hydrorefining, sulfuric acid washing, and clay treatment may be mentioned.

  Examples of the synthetic hydrocarbon oil include poly α-olefin (polybutene, 1-octene oligomer, 1-decene oligomer, etc.), alkylbenzene, alkylnaphthalene, and the like.

  Examples of the synthetic oxygen-containing oil include esters such as monoesters of monohydric alcohols and monohydric fatty acids, polyol esters of polyhydric alcohols and monohydric fatty acids, and polyoxyalkylene glycols.

  As fats and oils, for example, vegetable oils such as palm oil, palm kernel oil, rapeseed oil, soybean oil, high oleic rapeseed oil, and high oleic sunflower oil are used.

  Among these, mineral oil and synthetic hydrocarbon oil are preferably used, and mineral oil is more preferably used.

The kinematic viscosity at 40 ° C. of the lubricating base oil is not particularly limited, but is preferably 15 mm ² / s or more, more preferably 20 mm ² / s or more, further preferably 25 mm ² / s or more, and most preferably 30 mm ² / s. That's it. The kinematic viscosity of the lubricating base oil at 40 ° C. is preferably 50 mm ² / s or less, more preferably 45 mm ² / s or less, still more preferably 40 mm ² / s or less, and most preferably 35 mm ² / s or less. . The kinematic viscosity at 40 ° C. of the lubricating base oil is preferably 15 mm ² / s or more from the viewpoint of evaporability, and the piping resistance is reduced when the kinematic viscosity at 40 ° C. of the lubricating base oil is 50 mm ² / s or less. This is preferable.

  The viscosity index of the lubricating base oil is not particularly limited, but is preferably 150 or more, more preferably 160 or more, still more preferably 170 or more, and most preferably 175 or more. When the viscosity index is 150 or more, it is possible to suppress an increase in the low-temperature kinematic viscosity when the high-temperature kinematic viscosity is ensured. On the other hand, the upper limit value of the viscosity index is not particularly limited, but is 250, for example.

  In the present specification, “kinematic viscosity” and “viscosity index” mean values measured according to JIS K 2283.

  The content of the lubricating base oil is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more based on the total amount of the composition. The content of the lubricating base oil is preferably 99% by mass or less, more preferably 98% by mass or less, based on the total amount of the composition. When the content of the lubricating base oil is 50% by mass or more, the excellent effect of the hydraulic fluid can be sufficiently exhibited.

  The hydraulic fluid composition of this embodiment comprises at least one selected from an olefin copolymer having a number average molecular weight of 20,000 or less and a copolymer of an α olefin having a number average molecular weight of 20,000 or less and a dicarboxylic acid ester. contains.

  In addition, the “number average molecular weight” in the present specification refers to a number average molecular weight in terms of polystyrene determined by a gel permeation chromatography (GPC) measurement method (standard substance: polystyrene).

  The olefin copolymer is a co-oligomer or copolymer of ethylene and α-olefin. Examples of the α-olefin include propylene, 1-butene and 1-pentene, and propylene is preferably used. The copolymer of ethylene and α-olefin is not particularly limited, and may be a random polymer or a block polymer.

  The number average molecular weight of the olefin copolymer is 18000 or less, preferably 16000 or less, more preferably 14000 or less, and still more preferably 10,000 or less. The number average molecular weight of the olefin copolymer is preferably 700 or more, more preferably 1000 or more, and further preferably 1500 or more. A number average molecular weight of 18000 or less is preferable in terms of pump efficiency, and a number average molecular weight of 700 or more is preferable because the effect of improving the viscosity index is increased.

  Examples of the copolymer of α-olefin and dicarboxylic acid ester include compounds represented by the following general formula (1).

In the above formula (1), R ¹ represents a linear or branched alkyl group. R ^{2 to} R ⁵ may be the same or different, and each represents hydrogen, a linear or branched alkyl group, an ester group represented by —R ⁶ —CO ₂ R ⁷ or —CO ₂ R ⁸ (R ⁶ Represents a linear or branched alkylene group, R ⁷ and R ⁸ may be the same or different and each represents a linear or branched alkyl group), and any of R ^{2 to} R ⁵ These two are the ester groups. X and Y may be the same or different and each represents a positive number.

  Here, the partial structure represented by the following general formula (2) in the general formula (1) is derived from an α-olefin, and the α-olefin having 3 to 20 carbon atoms is used. Preferably, those having 6 to 18 carbon atoms are used.

  Specific examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, Examples include 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicocene and the like.

  The partial structure represented by the following general formula (3) in the general formula (1) is derived from a dicarboxylic acid ester.

  Specific examples of the dicarboxylic acid include maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid and the like.

  The number average molecular weight of the copolymer of α-olefin and dicarboxylic acid diester is 20000 or less, preferably 18000 or less, more preferably 14000 or less, still more preferably 12000 or less, and most preferably 10,000 or less. The number average molecular weight is preferably 20000 or less from the viewpoint of improving pump efficiency. The number average molecular weight of the copolymer of α-olefin and dicarboxylic acid diester is not particularly limited, but is preferably 5000 or more, more preferably 6000 or more, and further preferably 8000 or more. A number average molecular weight of 5,000 or more is preferred from the viewpoint of viscosity improving ability.

The kinematic viscosity at 100 ° C. of the copolymer of α-olefin and dicarboxylic acid ester is not particularly limited, but is preferably 1 mm ² / s or more, more preferably 10 mm ² / s or more, further preferably 50 mm ² / s or more, most preferably at 200 mm ² / s or more, and preferably 5000 mm ² / s or less, more preferably 3000 mm ² / s or less, more preferably 2000 mm ² / s or less, and most preferably not more than 1000 mm ² / s. When the kinematic viscosity at 100 ° C. is 1 mm ² / s or more, it is preferable from the viewpoint of increasing the viscosity, and when it is 5000 mm ² / s or less, it is preferable from the viewpoint of handling during production.

  In this embodiment, when using together the olefin copolymer and the copolymer of alpha olefin and dicarboxylic acid ester, those ratios are not specifically limited, but are arbitrary.

  The content of the copolymer is 0.2 to 40% by mass based on the total amount of the composition. When the content of the copolymer is 0.2% by mass or more, the blending effect is easily obtained. Moreover, when content is 40 mass% or less, it is preferable at the point of solubility or stability.

  When the olefin copolymer is used alone as the copolymer, the content of the copolymer is preferably 20% by mass or less, more preferably 15% by mass or less, and further preferably 10% by mass or less, based on the total amount of the composition. Most preferably, it is 8 mass% or less. The copolymer content is 0.2% by mass or more, more preferably 0.5% by mass or more, further preferably 1% by mass or more, and most preferably 3% by mass or more, based on the total amount of the composition. .

  When a copolymer of α-olefin and dicarboxylic acid ester is used alone as a copolymer, the content of the copolymer is 40% by mass or less, preferably 35% by mass or less, based on the total amount of the composition. Preferably it is 30 mass% or less, More preferably, it is 25 mass% or less. The content of the copolymer is preferably 1% by mass or more, more preferably 3% by mass or more, further preferably 5% by mass or more, and most preferably 10% by mass or more, based on the total amount of the composition.

  When an olefin copolymer and a copolymer of an α-olefin and a dicarboxylic acid ester are used in combination as the copolymer, the content of the copolymer is 40% by mass or less, preferably 35%, based on the total amount of the composition. It is at most 30% by mass, more preferably at most 30% by mass, even more preferably at most 25% by mass. The content of the copolymer is 0.1% by mass or more, preferably 1% by mass or more, more preferably 3% by mass or more, and further preferably 5% by mass or more, based on the total amount of the composition.

  If the content of the olefin copolymer and / or the copolymer of α-olefin and dicarboxylic acid ester is not less than the above-mentioned predetermined amount, the effect of blending can be easily obtained, and if it is not more than the above-mentioned predetermined amount, solubility or It is preferable in terms of stability.

The kinematic viscosity at 40 ° C. of the hydraulic fluid composition is not particularly limited, but is preferably 20 mm ² / s or more, more preferably 30 mm ² / s or more, further preferably 40 mm ² / s or more, and most preferably 45 mm ² / s. s or more. The kinematic viscosity at 40 ° C. of the hydraulic fluid composition is preferably 80 mm ² / s or less, more preferably 70 mm ² / s or less, further preferably 60 mm ² / s or less, and most preferably 50 mm ² / s or less. is there. The kinematic viscosity at 40 ° C. of the hydraulic fluid composition is preferably 20 mm ² / s or more from the viewpoint of durability of the hydraulic system, and is preferably 80 mm ² / s or less from the viewpoint of friction reduction.

  The viscosity index of the hydraulic fluid composition is preferably 150 or more, more preferably 155 or more, further preferably 160 or more, and most preferably 165 or more. A viscosity index of 150 or more is preferable because the optimum viscosity range can be maintained in a wide temperature range. On the other hand, the upper limit value of the viscosity index is not particularly limited, but is 250, for example.

The ratio (A / B) of (A) kinematic viscosity at 80 ° C. and (B) shear viscosity at 80 ° C. (unit: mPa · s, shear condition: 10 ⁶ / s) of the hydraulic fluid composition is particularly Although not limited, it is preferably 1.4 or less, more preferably 1.3 or less, still more preferably 1.25 or less, and most preferably 1.2 or less. The above A / B is preferably 1.4 or less in terms of pump efficiency and piping resistance. On the other hand, the lower limit value of A / B is not particularly limited, but is 1.1, for example.

  In addition, the “shear viscosity” in this specification means a value measured in accordance with ASTM (D4741, D4683, D6616) and CEC (L-36A-90).

  In order to further improve the excellent effects of the hydraulic fluid composition according to the present embodiment, an extreme pressure agent, an antioxidant, a pour point depressant, a rust inhibitor, a metal deactivator, It may further contain a viscosity index improver, an antifoaming agent, a demulsifier, an oily agent and the like. These additives may be used individually by 1 type, or may be used in combination of 2 or more type.

  Examples of extreme pressure agents include sulfur compounds such as sulfurized esters, sulfurized fats and oils, polysulfides, zinc dithiophosphate, and phosphorus compounds, and phosphorus compounds are preferably used. Specific examples include phosphoric acid esters, acidic phosphoric acid esters, amine salts of acidic phosphoric acid esters, chlorinated phosphoric acid esters, phosphorous acid esters, and phosphorothioates. Examples of these phosphorus compounds include esters of phosphoric acid, phosphorous acid or thiophosphoric acid and alkanols, polyether type alcohols, or derivatives thereof.

  Among the above phosphorus compounds, phosphoric acid ester, acidic phosphoric acid ester, and amine salt of acidic phosphoric acid ester are preferable, and among them, phosphoric acid ester is more preferable. The content of the extreme pressure agent is preferably 0.05 to 5% by mass based on the total amount of the composition.

  Examples of the antioxidant include phenolic compounds such as 2,6-ditertiarybutyl-p-cresol (DBPC), aromatic amines such as phenyl-α-naphthylamine, hindered amine compounds, phosphites, and organometallic compounds. Is mentioned. The content of the phenolic antioxidant is preferably 0.01 to 2% by mass based on the total amount of the composition. Moreover, it is preferable that content of an amine antioxidant is 0.001-2 mass% on the composition whole quantity basis.

  Examples of the pour point depressant include a copolymer of at least one monomer selected from various acrylic esters and methacrylic esters or a hydrogenated product thereof. The content of the pour point depressant is preferably 0.01 to 5% by mass based on the total amount of the composition.

  Rust inhibitors include amino acid derivatives, partial esters of polyhydric alcohols; esters such as lanolin fatty acid esters, alkyl succinic acid esters, alkenyl succinic acid esters; sarcosine; polyhydric alcohol partial esters such as sorbitan fatty acid esters; fatty acid metals Examples thereof include metal soaps such as salts, lanolin fatty acid metal salts and oxidized wax metal salts; sulfonates such as calcium sulfonate and barium sulfonate; oxidized wax; amines; phosphoric acid; The content of the rust inhibitor is preferably 0.01 to 5% by mass based on the total amount of the composition.

  Examples of the metal deactivator include benzotriazole, thiadiazole, and imidazole compounds. The content of the metal deactivator is preferably 0.001 to 1% by mass based on the total amount of the composition.

  The hydraulic fluid composition of the present embodiment can further contain a viscosity index improver other than the above copolymer. Specific examples thereof include a copolymer of at least one monomer selected from various methacrylates or a hydride thereof, a polyisobutylene or a hydrogenated product thereof, a hydride of a styrene-diene copolymer, and a non-alkylated styrene. Examples thereof include a dispersion type viscosity index improver. The content of the viscosity index improver other than the copolymer is preferably 0.01 to 15% by mass based on the total amount of the composition.

  Examples of antifoaming agents include silicones such as dimethyl silicone and fluorosilicone. The content of the antifoaming agent is preferably 0.001 to 0.05% by mass based on the total amount of the composition.

  Examples of the demulsifier include polyoxyalkylene glycol, polyoxyalkylene alkyl ether, polyoxyalkylene alkylamide, polyoxyalkylene fatty acid ester and the like.

  Examples of oily agents include fatty acids, esters, alcohols and the like. The content of the oily agent is preferably 0.01 to 0.5% by mass based on the total amount of the composition.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to these content at all.

  In Examples 1 to 4 and Comparative Examples 1 to 4, lubricating oil base oils and additives were blended with the compositions shown in Tables 1 and 2 to prepare hydraulic fluid compositions. The lubricating base oils and additives used in the examples and comparative examples are as follows.

<Lubricant base oil>
Base oil 1: hydrorefined mineral oil (total aromatic content: 0.0 mass%, sulfur content: 10 mass ppm or less, 40 ° C. kinematic viscosity: 20 mm ² / s, viscosity index: 124)
Base oil 2: hydrorefined mineral oil (total aromatic content: 0.0 mass%, sulfur content: 10 mass ppm or less, 40 ° C. kinematic viscosity: 26 mm ² / sec, viscosity index: 131)
Base oil 3: hydrorefined mineral oil (total aromatic content: 0.0 mass%, sulfur content: 10 mass ppm or less, 40 ° C. kinematic viscosity: 46 mm ² / sec, viscosity index: 127)

  Here, the total aromatic content was measured by Analytical Chemistry Vol. 44 No. 6 (1972) pp. 915-919 “Separation of High-Boiling Petroleum Distiled Alu-Gel Elution Min-Gold Elution Aid-Gold-Et. It measured according to the silica-alumina gel chromatographic analysis method described in "."

  Also, the sulfur content was measured by ASTM D4951 “Standard Test Method for Determining of Additive Elements in Lubricating Oils by Inductively Coupled Plasma Atomic Emission.

  The kinematic viscosity and the viscosity index were measured according to JIS K 2283.

<Viscosity index improver>
A: Ethylene propylene copolymer (Mitsui Chemicals Co., Ltd .: Lucant HC2000, number average molecular weight 13100)
B: Copolymer of α-olefin and dicarboxylic acid ester (Ketjenrub Co., Ltd .: KL2700, number average molecular weight 9800, kinematic viscosity at 100 ° C. 700 mm ² / sec)
C: Styrene-diene copolymer (Infinium: SV151, number average molecular weight 144000)
D: Polymethacrylate (manufactured by Sanyo Kasei Co., Ltd., number average molecular weight 40000)
E: Polymethacrylate (manufactured by Sanyo Kasei Co., Ltd., number average molecular weight 100,000)
F: Olefin copolymer (manufactured by Chevron: PARATONE 8451, number average molecular weight 230000)

<Other additives>
In Examples 1 to 4 and Comparative Examples 1 to 4, tricresyl phosphate, 2,6-ditertiary butyl-p-cresol (DBPC) and pour point depressant were added as other additives, respectively, based on the total amount of the composition. 0.5% by mass.

About each hydraulic fluid composition obtained in Examples 1-4 and Comparative Examples 1-4, each property was measured as follows. The results are shown in Tables 1 and 2.
Kinematic viscosity and viscosity index: Measured according to JIS K 2283.
Shear viscosity: Measured according to ASTM (D4741, D4683, D6616) and CEC (L-36A-90) at 80 ° C. under shear conditions of 10 ⁶ / s. As a measuring device, a USV (Ultra Shear Viscometer) viscometer manufactured by PCS Instruments was used.

[HPV35 + 35 pump test]
The HPV 35 + 35 pump test was performed on each hydraulic fluid composition obtained in Examples 1-4 and Comparative Examples 1-4. Specifically, the rotational torque of the pump was measured under the following test conditions, and the total efficiency was calculated. The results are shown in Tables 1 and 2.
Pump name: Komatsu HPV35 + 35
Discharge amount + drain amount: 40 L / min
Pump type: Swash plate type Oil temperature: 80 ℃
Pressure: No load, 35 MPa
Pump rotation: 2100 rpm

Claims (2)

Lubricating base oil,
At least one selected from an olefin copolymer having a number average molecular weight of 18,000 or less and a copolymer of an α-olefin having a number average molecular weight of 20000 or less and a dicarboxylic acid ester of 0.2 to 40% by mass based on the total amount of the composition. A copolymer of
A hydraulic fluid composition comprising: (A) Kinematic viscosity at 80 ° C. (unit: mm ² / s) and (B) Shear viscosity at 80 ° C. (unit: mPa · s, shear condition: 10 ⁶ / s). The hydraulic fluid composition according to claim 1, wherein the ratio (A / B) to 1.3 is 1.3 or less.