JP6055320B2 - Hydraulic fluid composition - Google Patents

Description

The present invention has a low coefficient of friction, excellent power saving performance, wear resistance, thermal oxidation stability, storage stability and demulsibility, such as construction machines, injection molding machines and press machines. The present invention relates to an industrial hydraulic fluid composition that can be used in hydraulic equipment.

In recent years, as a measure against global warming, reduction of carbon dioxide emissions has become an urgent task, and in the industry, efforts are being made to save energy in industrial machines and transport equipment. In Japan, the Law Concerning Rational Use of Energy and the Law Concerning Promotion of Global Warming Countermeasures were revised and implemented in 2006, and factories, transportation companies, etc. have been required to reduce power consumption more than ever. I came.

One method of reducing power consumption in the industry is to change the hydraulic fluid used in hydraulic equipment such as construction machines, injection molding machines, and press machines to a power-saving type. This method only needs to replace the hydraulic fluid with a power-saving type, and can contribute to power saving without the need for modification of the equipment.

As one of methods for imparting power saving performance to hydraulic fluid, a technique of blending a friction reducing agent with hydraulic fluid is known (for example, Patent Documents 1 and 2). Among the components of industrial hydraulic equipment, hydraulic pumps (gear pumps, vane pumps, piston pumps), hydraulic motors (gear motors, vane motors, piston motors), pistons / cylinders, etc. have sliding parts. In view of the above, energy saving is achieved by reducing energy loss due to friction of these sliding portions.

In addition, as a method for imparting power saving performance to a hydraulic fluid, a technique of blending a viscosity index improver such as an olefin copolymer or poly (meth) acrylate having a predetermined molecular weight with a low-viscosity base oil is also known ( For example, Patent Documents 3 to 5). This is a very narrow component of the industrial hydraulic system, where the hydraulic fluid flows inside the hydraulic pump, various control valves such as flow rate, direction and pressure, and actuators such as cylinders and hydraulic motors. This technique focuses on having a route. In such a narrow path through which the hydraulic fluid flows, exposure to high shear conditions increases pressure loss, which tends to cause energy loss. From this point of view, the above technique aims to save power by reducing the temporary shear viscosity (hereinafter referred to as “high shear viscosity”) under high shear conditions.

JP 2007-327069 A JP 2008-195953 A JP 2010-215698 A JP 2010-215699 A JP 2011-46900 A

As described above, various studies have been recently made on the technology for enhancing the power saving effect of the hydraulic fluid, and further improvement of the effect is expected.

On the other hand, it is also required that the basic performance of the hydraulic fluid, such as wear resistance, thermal oxidation stability, and demulsibility, be good. However, the power saving effect improving technology may adversely affect the basic performance of such hydraulic fluid.

For example, in the technique of blending a friction reducing agent, the friction reducing agent is a substance having a high polarity and a hydrophilic group because it has a function of adsorbing to a metal surface to hold an oil film and prevent direct contact between metal and metal. There are many cases. Therefore, the friction reducing agent may have poor solubility in the base oil and adversely affect storage stability. Also, the wear resistance of the hydraulic fluid may be reduced due to competitive adsorption with an antiwear or extreme pressure agent. Furthermore, there is a possibility that the demulsibility is lowered to promote the affinity with water.

In addition, when considering the improvement of the power saving effect of the entire target device, it is considered preferable to combine the technology of blending friction reducers with different principles with the technology of blending viscosity index improvers. When a hydraulic fluid is prepared with a combination of an agent and a viscosity index improver, the performance as a hydraulic fluid may be adversely affected, such as deteriorating storage stability, demulsibility, and abrasion resistance.

As a result of intensive studies to solve the above problems, the present inventors have improved the friction reducing effect by adding a specific amount of a fatty acid and a specific fatty acid amide to the base oil. It was found that the basic performance can be secured, and further the basic performance can be secured even when the viscosity index improver is used in combination, and the present invention has been completed.

（一般式（１）及び一般式（２）中のＲ_１、Ｒ_３及びＲ_５は炭素数６〜２４の直鎖もしくは分岐鎖の脂肪族炭化水素基を表し、Ｒ_２は水素原子または炭素数１〜２４の直鎖もしくは分岐鎖の脂肪族炭化水素基を表し、Ｒ_４は炭素数１〜６の直鎖もしくは分岐鎖の２価の脂肪族炭化水素基を表す。）
また、本発明は、上記油圧作動油組成物において、前記一般式（１）において、Ｒ２が水素原子またはメチル基である油圧作動油組成物を提供するものである。 That is, the present invention comprises (a) at least one base oil selected from mineral oil and / or synthetic oil, (b) 0.02 to 0.8 % by mass of fatty acid,
(C) 0.01 to 1.0% by mass of a fatty acid amide selected from the fatty acid monoamide represented by the following general formula (1) and the fatty acid bisamide represented by the following general formula (2),
A hydraulic fluid composition characterized by containing (however, having a mesogenic structure in the molecule, a viscosity-pressure coefficient at 40 ° C. of 20 GPa ⁻¹ or less, and friction with increasing pressure under a pressure of 10 MPa or more. Excluding those containing at least one organic compound that develops a minimum value of the coefficient) .

(R ₁ , R ₃ and R ₅ in the general formula (1) and the general formula (2) represent a linear or branched aliphatic hydrocarbon group having 6 to 24 carbon atoms, and R ₂ represents a hydrogen atom or carbon. A straight or branched aliphatic hydrocarbon group having 1 to 24 carbon atoms is represented, and R ₄ represents a straight or branched divalent aliphatic hydrocarbon group having 1 to 6 carbon atoms.)
The present invention also provides the hydraulic fluid composition as described above, wherein in the general formula (1), R2 is a hydrogen atom or a methyl group.

The present invention, in the oil pressure hydraulic oil composition, (d) a weight average molecular weight of 70,000 to 200,000 of the poly (meth) acrylate 0.06 to 3% by weight, (e) a weight average molecular weight 5000 the 100,000 olefin copolymer 0.1 to 5 wt%, there is provided a hydraulic working oil composition characterized by blending.

Furthermore, the present invention is the oil pressure hydraulic oil composition, there is provided a hydraulic working oil composition characterized by containing 5 to 95 ppm by weight (f) demulsifier.

ADVANTAGE OF THE INVENTION According to this invention, the hydraulic fluid composition which improved the power saving performance by having a low friction coefficient is realizable. At the same time, it is possible to realize a hydraulic fluid composition having good basic properties such as wear resistance, thermal oxidation stability, storage stability and demulsibility. Furthermore, these basic performances can be maintained by the combined use of a viscosity index improver. Therefore, the hydraulic fluid composition of the present invention can be suitably used as an industrial hydraulic fluid for hydraulic equipment such as construction machines, injection molding machines, and press machines.

(A) Base oil The base oil used in the hydraulic fluid composition of the present invention is not particularly limited as long as it is a base oil normally used as a hydraulic fluid, but JIS K 2283 “Kinematic viscosity test” can be used. It is preferable to use a hydrocarbon base oil having a kinematic viscosity of 28 to 51 mm ² / s at 40 ° C. measured by the “method”, and more preferably 30 to 48 mm ² / s. The kinematic viscosity of the base oil here refers to the kinematic viscosity after mixing when two or more different base oils are mixed. Hereinafter, the base oil of the present invention that is preferably used alone or in combination is referred to as a “base oil portion”. 28 kinematic viscosity of the base oil part is 28
By setting it to mm ² / s or more, it is easy to ensure a flash point of 250 ° C. or more. In addition, it is easy to suppress a decrease in volumetric efficiency of the pump, and even when used in a high pressure hydraulic device of 10 MPa or more, it is easy to hold an oil film, and it is easy to suppress the influence on wear resistance. Moreover, the power-saving effect improvement by pressure loss suppression can be anticipated by making 40 degreeC kinematic viscosity of a base oil part into 51 mm < ² > / s or less. Lubricating oils with a flash point of 250 ° C. or higher are classified as “designated flammables and flammable liquids” in the Fire Service Law, except for some, and are advantageous in terms of storage and management.

The density of the base oil or base oil part used in the hydraulic fluid composition of the present invention is preferably such that the density at 15 ° C. is in the range of 0.8200 to 0.8500 g / cm ³ , and 0.8300 to 0.8. What is in the range of 8500 g / cm < ³ > is more preferable. By setting the density of the base oil portion to 0.8200 g / cm ³ or more, it is easy to ensure a flash point of 250 ° C. or more. Moreover, by setting the density of the base oil portion to 0.8500 g / cm ³ or less, the absolute viscosity can be kept low, the pressure loss is suppressed, and a higher power saving effect can be expected.

The base oil or base oil part used in the hydraulic fluid composition of the present invention is a distillation test (hereinafter referred to as GC) in accordance with “6. Gas chromatographic distillation test method” of JIS K 2254 “Petroleum products-distillation test method”. The initial distillation point is 350 ° C. or higher, and the 5% distillation temperature is preferably 380 ° C. or higher, and the initial distillation point is 370 ° C. or higher and the 5% distillation temperature is 390 ° C. or higher. More preferably. By setting the initial boiling point in the GC distillation of the base oil portion to 350 ° C. or higher and the 5% distillation temperature to 380 ° C. or higher, the flash point becomes 250 ° C. or higher when the hydraulic fluid composition is prepared.

The base oil or base oil part used in the hydraulic fluid composition of the present invention has a percent CP of 72 to 90, a percent CN of 10 to 28, and a percent CA of 2 in ASTM D3238 “ndm ring analysis method”. Preferably,% CP is 75 to 88,% CN is 12 to 25, and% CA is 1 or less. By setting% CP to 72 or more,% CN to 28 or less, and% CA to 2 or less, it is easy to ensure a high viscosity index without increasing the addition amount of the viscosity index improver, and the density tends to decrease. Therefore, it is preferable. In addition, by setting% CP to 90 or less and% CN to 10 or more, it is easy to ensure the solubility of various additives including the fatty acid of component (b) and the fatty acid amide of component (c) of the present invention. This is preferable.

The base oil or base oil part used in the hydraulic fluid composition of the present invention preferably has a viscosity index of 110 or more, more preferably 120 or more. By setting the viscosity index to 110 or more, the viscosity index when the hydraulic fluid composition is prepared is increased. As a result, the low-temperature viscosity is decreased, so that it is easy to reduce power consumption at low-temperature start. In addition, the viscosity index of the composition can be increased as the blending amount of the viscosity index improver is increased. However, if the viscosity index of the base oil is high, the blending amount can be suppressed, and filterability can be improved. , It can improve storage stability and keep costs low. Moreover, when the compounding quantity of a viscosity index improver is suppressed, when it combines with the fatty acid of (b) component of this invention and the fatty acid amide of (c) component, it is easy to suppress the influence on storage stability.

The base oil or base oil part used in the hydraulic fluid composition of the present invention is preferably 110 ° C. to 130 ° C., more preferably 120 ° C. to 130 ° C. in JIS K 2256 “aniline point test method”. preferable. It is preferable to set the aniline point to 110 ° C. or higher because a high viscosity index and a low density can be easily obtained and a power saving effect by suppressing pressure loss can be expected. Moreover, it is preferable to set the aniline point to 130 ° C. or lower because it tends to ensure the solubility of the additive. Also, from the viewpoint of ensuring compatibility with the sealing material, the aniline point needs to be in an appropriate range, and from this viewpoint, it is preferably 110 ° C to 130 ° C.

The base oil contained in the base oil portion of the hydraulic fluid composition of the present invention is not particularly limited as long as it has the above properties when used alone or in combination. As the base oil constituting the base oil portion having the above-mentioned properties, base oils mainly composed of paraffin or isoparaffin such as solvent refined mineral oil, hydrorefined mineral oil, hydrocracked mineral oil, hydrocarbon-based synthetic oil are suitable. Used for. Of these, hydrorefined mineral oil and hydrocracked mineral oil are preferably used, and hydrocracked mineral oil is particularly preferred. Although the manufacturing method of hydrorefining mineral oil and hydrocracked mineral oil is not specifically limited, As a preferable manufacturing method, the following method is mentioned. First, residual oil obtained by atmospheric distillation of crude oil is treated with a vacuum distillation apparatus. The vacuum gas oil thus obtained is hydrotreated and hydrocracked, and then a residue obtained by removing light and fuel components with a vacuum stripper is obtained. This residue is distilled under reduced pressure, and the resulting lubricating oil fraction is subjected to hydrodewaxing treatment or wax isomerization treatment and stabilization treatment. At that time, those having a high viscosity index by wax isomerization are more preferably used.

In the case where a hydrocarbon synthetic oil is used as the base oil contained in the base oil portion of the hydraulic fluid composition of the present invention, a polyα olefin is preferably used. As a suitable production example of poly α-olefin, an α-olefin having 6 to 18 carbon atoms is synthesized by low polymerization of ethylene or thermal decomposition of wax, 2 to 9 units of this α-olefin are polymerized, and hydrogenation reaction is performed. Synthesized by doing. In addition, base oils obtained by hydrocracking and hydroisomerization of raw materials such as slack wax by solvent dewaxing and wax obtained by Fischer-Tropsch synthesis, base oils such as alkylnaphthalene and alkylbenzene, etc. Aromatic hydrocarbon oils can also be suitably used. When using these hydrocarbon synthetic oils, hydroisomerized base oils of wax raw materials, and aromatic hydrocarbon oils, solvent refined mineral oils, hydrogenation to make% CP and% CN within appropriate ranges It is more preferable to use a mixture of refined mineral oil, hydrocracked mineral oil or the like.

The above-mentioned hydrocarbon base oil is used for the base oil portion of the hydraulic fluid composition of the present invention, but other than hydrocarbons such as ester oils and alkylated phenyl ether oils as long as they do not affect the effects of the present invention. These synthetic base oils can also be used. However, since synthetic base oils other than hydrocarbon base oils have a high density, when these base oils are used, it is preferable to mix them at a ratio of 30% or less of the base oil portion, and a ratio of 20% or less. More preferably, a ratio of 10% or less is more preferable, and a ratio of 5% or less is most preferable.

In the hydraulic fluid composition of the present invention, the content of the base oil part is preferably 85 to 99.5% by mass, more preferably 87 to 99% by mass, based on the total amount of the hydraulic fluid composition. More preferably, it is 90-98 mass%.

(B) Fatty acid The fatty acid used in the hydraulic fluid of the present invention is blended as one type of friction modifier. Moreover, there exists an effect | action which raises the solubility to the base oil of the fatty acid amide of (c) component mix | blended similarly as 1 type of a friction modifier. Although the fatty acid amide has a high friction reducing effect, it has a low solubility in the base oil, so the addition amount has to be small, and as a result, it is difficult to obtain a sufficient friction reducing effect by itself. Moreover, even if the addition amount is small, there is a concern about the effect on storage stability because it is likely to precipitate at a low temperature. The blending of the fatty acid in the present invention has the effect of increasing the solubility of the fatty acid amide having such properties, and as a result, the friction reducing effect of the fatty acid amide can be further enhanced, and at the same time, the storage stability is also improved. You can also.

Although there is no restriction | limiting in particular as a fatty acid used for the hydraulic fluid of this invention, A C6-C28 thing is preferable and a thing of 12-24 is more preferable because the solubility to a base oil is favorable. The carboxyl group of the fatty acid is preferably divalent (dicarboxylic acid) or monovalent (monocarboxylic acid), more preferably monovalent. Those having a valence of 3 or more are not preferred because the demulsibility may be inferior. Further, the aliphatic hydrocarbon group of the fatty acid may be linear or branched, but is preferably linear. Moreover, although a saturated type or an unsaturated type may be sufficient, an unsaturated type is more preferable, and in the case of an unsaturated type, what an unsaturated group is a carbon-carbon double bond is preferable. In the case of the unsaturated type, the number of carbon-carbon double bonds is preferably 1 to 4, more preferably 1 to 2, and particularly preferably 1.

Examples of the fatty acids include (iso) caproic acid, (iso) caprylic acid, (iso) capric acid, (iso) undecanoic acid, (iso) lauric acid, (iso) tridecylic acid, Iso) myristic acid, (iso) pentadecylic acid, (iso) palmitic acid, (iso) margaric acid, (iso) stearic acid, (iso) nonadecyl acid, (iso) arachidic acid, (iso) behenic acid, (iso) Examples include lignoceric acid, (iso) cellotic acid, (iso) montanoic acid and the like. In the case of the unsaturated type, (iso) β-propylacrylic acid, (iso) caproleic acid, (iso) undecylenic acid, (iso) lauroleic acid, (iso) lindelic acid, (iso) tuzuic acid, ( Iso) myristoleic acid, (iso) palmitoleic acid, (iso) zomarinic acid, (iso) petroceric acid, (iso) petroceridic acid, (iso) oleic acid, (iso) elaidic acid, (iso) basenic acid, (Iso) codoic acid, (iso) gonodoic acid, (iso) cetroleic acid, (iso) erucic acid, (iso) brassic acid, (iso) ceracoleic acid, and the like.

These fatty acids may be used alone or in combination of two or more. Fatty acids used in the present invention is 0.02 to 0.8% by weight with respect to hydraulic fluid composition total amount, particularly preferably from 0.05 to 0.5 wt%. When the content is less than 0.02 % by mass, the effect of the fatty acid cannot be obtained sufficiently. On the other hand, if it exceeds 0.8 % by mass, thermal oxidation stability and demulsibility may be inferior, and an improvement in the effect commensurate with the blending amount cannot be expected. In order to reduce the friction coefficient, it is particularly preferable that the content of the fatty acid is 0.15 to 0.4 mass% with respect to the total amount of the hydraulic fluid composition.

(C) Fatty acid amide The fatty acid amide used in the hydraulic fluid of the present invention is blended as one type of friction modifier. As described above, since fatty acid amides are not particularly soluble in base oils at low temperatures, a high friction reduction effect and good storage stability can be obtained by using the fatty acid of component (b) in combination. .
The fatty acid amide for use in hydraulic oils of the present invention, preferably has a carbon number of 6 to 40, more preferable because those 12 to 24 are good solubility in the base oil. The amide group of the fatty acid amide is preferably divalent (bisamide) or monovalent (monoamide), and more preferably monoamide. On the other hand, those having a valence of 3 or more are not preferable because the demulsibility may be inferior.
Compound represented by the general formula (1) as the fatty acid monoamide, Ru compound der represented by the general formula (2) as the fatty acid bisamide.

（一般式（１）及び一般式（２）中のＲ_１、Ｒ_３及びＲ_５は炭素数６〜２４の直鎖もしくは分岐鎖の脂肪族炭化水素基を表し、Ｒ_２は水素原子または炭素数１〜２４の直鎖もしくは分岐鎖の脂肪族炭化水素基を表し、Ｒ_４は炭素数１〜６の直鎖もしくは分岐鎖の２価の脂肪族炭化水素基を表す。）

(R ₁ , R ₃ and R ₅ in the general formula (1) and the general formula (2) represent a linear or branched aliphatic hydrocarbon group having 6 to 24 carbon atoms, and R ₂ represents a hydrogen atom or carbon. A straight or branched aliphatic hydrocarbon group having 1 to 24 carbon atoms is represented, and R ₄ represents a straight or branched divalent aliphatic hydrocarbon group having 1 to 6 carbon atoms.)

R ₁ in the general formula (1) is an aliphatic hydrocarbon group having 6 to 24 carbon atoms, preferably 10 to 22 carbon atoms, and more preferably 16 to 20 carbon atoms. R1 may be linear or branched, but is more preferably linear. R1 may be saturated or unsaturated, but is preferably unsaturated. In the unsaturated type, R1 is preferably a carbon-carbon double bond. Furthermore, when R1 is unsaturated, the number of carbon-carbon double bonds is preferably 1 to 4, more preferably 1 to 2, and particularly preferably 1. On the other hand, R2 is a hydrogen atom or an aliphatic hydrocarbon group having 1 to 24 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and most preferably a hydrogen atom or a methyl group.

In the general formula (2), R ₃ and R ₅ are aliphatic hydrocarbon groups having 6 to 24 carbon atoms, preferably 10 to 22 carbon atoms, and more preferably 16 to 20 carbon atoms. . R ₃ and R ₅ may be linear or branched, but are more preferably linear. R ₃ and R ₅ may be saturated or unsaturated, but are preferably unsaturated, and in the case of unsaturated, the unsaturated group is preferably a carbon-carbon double bond. . Further, when R ₃ and R ₅ are unsaturated, the number of carbon-carbon double bonds is preferably 1 to 4, more preferably 1 to 2, and particularly preferably 1. On the other hand, R ₄ is a linear or branched divalent aliphatic hydrocarbon group having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, and more preferably 2 carbon atoms. R ₄ may be linear or branched, but is more preferably linear. R ₄ may be saturated or unsaturated, but is preferably saturated.

Specific examples of the fatty acid amide include bisamides such as ethylene bis-stearic amide, ethylene bis-isostearic amide, ethylene bis-oleic amide, ethylene bis-erucic amide, (iso) caproic monoamide, (iso) Caprylic acid monoamide, (iso) capric acid monoamide, (iso) undecanoic acid monoamide, (iso) lauric acid monoamide, (iso) tridecylic acid monoamide, (iso) myristic acid monoamide, (iso) pentadecyl acid monoamide, (iso) palmitin Saturated fatty acid monoamides such as acid monoamide, (iso) margaric acid monoamide, (iso) stearic acid monoamide, (iso) nonadecyl acid monoamide, (iso) arachidic acid monoamide, (iso) behenic acid monoamide, (iso) caproleic acid Noamide, (Iso) undecylenic acid monoamide, (Iso) lauroleic acid monoamide, (Iso) lindelic acid monoamide, (Iso) Tuzic acid monoamide, (Iso) myristoleic acid monoamide, (Iso) palmitoleic acid monoamide, (Iso) Zomarin Acid monoamide, (iso) petroceric acid monoamide, (iso) petroselinic acid monoamide, (iso) oleic acid monoamide, (iso) elaidic acid monoamide, (iso) basenic acid monoamide,

Unsaturated fatty acid monoamides such as (iso) codoic acid monoamide, (iso) gonodoic acid monoamide, (iso) cetroleic acid monoamide, (iso) erucic acid monoamide, N-methyl (iso) lauric acid amide, N-methyl (iso ) Tridecylic acid amide, N-methyl (iso) myristic acid amide, N-methyl (iso) pentadecylic acid amide, N-methyl (iso) palmitic acid amide, N-methyl (iso) margaric acid amide, N-methyl (iso ) Stearic acid amide, N-methyl (iso) nonadecyl amide, N-methyl (iso) arachidic acid amide, N-methyl (iso) behenic acid amide, N-methyl (iso) lauroleic acid amide, N-methyl (iso ) Lindelamide, N-methyl (iso) zutamide, N-methyl (iso) myristole Acid amide, N-methyl (iso) palmitoleic acid amide, N-methyl (iso) zomarinic acid amide, N-methyl (iso) petroceric acid amide, N-methyl (iso) petroceledic acid amide, N-methyl (iso ) Oleic acid amide, N-methyl (iso) elaidic acid amide, N-methyl (iso) basenic acid amide, N-methyl (iso) codoic acid amide, N-methyl (iso) gonodoic acid amide, N-methyl (iso N-methyl fatty acid amides such as) cetrolein acid amide, N-methyl (iso) erucic acid amide, (iso) stearic acid (iso) caprylamide, (iso) stearic acid (iso) stearyl amide, (iso) stearic acid ( Iso) oleylamide, (iso) oleic acid (iso) caprylamide, (iso) oleic acid (iso) ste Riruamido, N- alkyl fatty acid amides such as (iso) Oleic acid (iso) oleylamide, and the like.

These fatty acid amides may be used alone or in combination of two or more. The fatty acid amide used in the present invention is preferably contained in an amount of 0.01% by mass to 1.0% by mass, more preferably 0.02% by mass to 0.8% by mass, based on the total amount of the hydraulic fluid composition. Preferably it is 0.03-0.5 mass%. If the content is less than 0.01% by mass, a sufficient friction reducing effect cannot be obtained. On the other hand, when it exceeds 1.0 mass%, thermal oxidation stability and storage stability may be inferior, and an improvement in the effect commensurate with the content may not be expected. In order to reduce the friction coefficient, it is particularly preferable that the content of the fatty acid amide is 0.06 to 0.3% by mass with respect to the total amount of the hydraulic fluid composition.
The content ratio of the fatty acid amide to the fatty acid is 10:90 to 60:40, preferably 15:85 to 50:50. By setting this ratio, a higher effect can be obtained.

(D) Poly (meth) acrylate In the hydraulic fluid composition of the present invention, in addition to the above (b) fatty acid and (c) fatty acid amide, in order to further enhance the power saving effect of the entire hydraulic equipment, It is preferable to mix | blend with (meth) acrylate and the olefin copolymer mentioned later. Unlike the above (b) fatty acid and (c) fatty acid amide, which increase the power saving effect by reducing friction, these increase the power saving effect by reducing the shear viscosity.

The poly (meth) acrylate (hereinafter sometimes referred to as PMA) that can be used in the hydraulic fluid of the present invention is specifically at least one selected from compounds represented by formula (1). Copolymerized with one or more monomers selected from non-dispersed PMA or a compound represented by formula (1) and a monomer having a polar group other than an acrylic group, The dispersion type PMA obtained by this is mentioned. These PMAs can be added as a viscosity index improver previously dissolved in a base oil (also referred to as diluent oil) when used in the hydraulic fluid composition of the present invention. A viscosity index improver based on non-dispersed PMA is called a non-dispersed PMA viscosity index improver, a viscosity index improver based on dispersed PMA is called a dispersed PMA viscosity index improver, Either of them can be used, but a non-dispersed PMA viscosity index improver is preferably used.

(R6 in Formula (3) represents a hydrogen atom or a methyl group and may be the same or different. R7 in Formula (3) is a linear or branched alkyl having 1 to 18 carbon atoms. Specific examples of monomers having polar groups include nitrogen atom-containing compounds such as alkyl-vinyl pyridine, N-vinyl pyrrolidone and vinyl imidazole, and esters such as polyalkylene glycol esters, maleic esters and fumaric esters. Kind. These may be used alone or in combination of two or more.

The weight average molecular weight of the poly (meth) acrylate is preferably 70,000 to 200,000, more preferably 100,000 to 180,000, and particularly preferably 120,000 to 160,000. When the weight average molecular weight is less than 70,000, the high shear viscosity can be lowered, and a high power saving effect based on poly (meth) acrylate is easily obtained. On the other hand, when the weight average molecular weight exceeds 200,000, the permanent shear stability is lowered, so that it is preferably 200,000 or less. The weight average molecular weight is measured by gel permeation chromatography and is a value in terms of polystyrene.

The number average molecular weight of the poly (meth) acrylate is preferably 20,000 to 80,000, more preferably 30,000 to 65,000. By setting the number average molecular weight to 20,000 or more, the high shear viscosity can be lowered, and a high power saving effect based on poly (meth) acrylate is easily obtained, which is preferable. Moreover, it is preferable for the number average molecular weight to be 80,000 or less because better permanent shear stability can be easily obtained. The number average molecular weight is measured by gel permeation chromatography and is a value in terms of polystyrene.

The poly (meth) acrylate has a Mw / Mn ratio of preferably 1.5 to 3.5, more preferably 1.9 to 3.0.
The above poly (meth) acrylates may be used alone or in combination of two or more. When two or more are used in combination, the weight average molecular weight and number average molecular weight are It is preferable to be in the above range.
The above poly (meth) acrylates may be used alone or in combination of two or more. When two or more are used in combination, the weight average molecular weight and number average molecular weight are It is preferable to be in the above range.

The blending amount of the poly (meth) acrylate with respect to the total amount of the hydraulic fluid composition is preferably 0.06 to 3% by mass, more preferably 0.1 to 2% by mass, and still more preferably 0.15 to 1%. 0.5% by mass. By setting the blending amount to 0.06% by mass or more, the viscosity index of the hydraulic fluid composition can be sufficiently increased, and the temporary shear viscosity under high shear conditions can be sufficiently reduced. A power saving effect based on (meth) acrylate is easily obtained. In addition, since poly (meth) acrylate has a relatively high compatibility with the additive as compared with the olefin copolymer, the blending amount is preferably 0.06% by mass or more from this point. On the other hand, if the blending amount exceeds 3% by mass, the permanent shear stability is deteriorated and it is difficult to ensure the solubility in the base oil.

(E) Olefin Copolymer In the hydraulic fluid composition of the present invention, in addition to the above-mentioned (b) fatty acid and (c) fatty acid amide, in order to further enhance the power saving effect of the entire hydraulic equipment, the above-mentioned poly ( It is preferable to blend an olefin copolymer with (meth) acrylate. As described above, these increase the power saving effect by lowering the shear viscosity.
The (e) olefin copolymer (hereinafter sometimes referred to as OCP) that can be used in the hydraulic fluid of the present invention is used as a viscosity index improver, and any copolymer of different olefins can be used. For example, a copolymer of ethylene and a monomer other than ethylene may be used.

Examples of monomers other than ethylene that form a copolymer with ethylene include olefin hydrocarbons, diene hydrocarbons, vinyl aromatics, and the like. These carbon number becomes like this. Preferably it is 3-30, More preferably, it is 3-25, More preferably, it is 3-15, Especially preferably, it is 3-8, Most preferably, it is 3-5. It is preferable for the number of carbon atoms in the monomer to be 30 or less because the molecular weight can be kept relatively low and shear resistance can be improved. The olefin hydrocarbon used as a monomer other than ethylene may be linear, cyclic, or branched. Specific examples include propylene, n-butene, i-butylene, cyclobutene, n-pentene, i-pentene, cyclopentene, n-hexene, i-hexene, n-heptene, i-heptene and the like. The diene hydrocarbon used as a monomer other than ethylene may be a chain, a ring, or a branched chain. Specific examples include butadiene, cyclobutadiene, pentadiene, cyclopentadiene, hexadiene, heptadiene and the like. Examples of the vinyl aromatic used as the monomer other than ethylene in the olefin copolymer include styrene and divinylbenzene.
Among these, it is particularly preferable to use an ethylene / propylene copolymer.

When a copolymer of ethylene and a monomer other than ethylene is used as the olefin copolymer, the molar ratio of the monomer other than ethylene and ethylene is not particularly limited, but is preferably 80:20 to 20:80, more preferably 70: It is 30-30: 70, More preferably, it is 65: 35-35: 65. When the ratio of ethylene exceeds 80, it tends to be difficult to dissolve in the base oil.

Such a copolymer may be any of regular alternating polymers, random polymers, block polymers, or graft polymers, and may be either dispersed or non-dispersed. From the viewpoint of stability, a non-dispersed copolymer is preferable.
These olefin copolymers can also be added as viscosity index improvers previously dissolved in a base oil (also referred to as diluent oil) when used in the hydraulic fluid composition of the present invention, as in PMA. Since the olefin copolymer used in the present invention has a relatively small molecular weight, it is often handled as a viscosity index improver without being dissolved in the base oil.

The weight average molecular weight of the olefin copolymer is preferably 5,000 to 100,000, more preferably 8,000 to 80,000, still more preferably 10,000 to 50,000, particularly preferably 10,000 to 20,000. By setting the weight average molecular weight to 5,000 or more, the temporary shear viscosity under high shear conditions can be sufficiently lowered, and the power saving effect based on the olefin copolymer can be easily obtained. If the weight average molecular weight exceeds 100,000, the permanent shear stability is lowered, so that it is preferably 100,000 or less. Here, the weight average molecular weight is measured by gel permeation chromatography and is a value in terms of polystyrene.

The number average molecular weight of the olefin copolymer is preferably 4,000 to 50,000, more preferably 6,000 to 30,000. By setting the number average molecular weight to 4,000 or more, the temporary shear viscosity under high shear conditions can be lowered, and the power saving effect based on the olefin copolymer tends to be easily obtained, which is preferable. In addition, it is preferable that the number average molecular weight is 50,000 or less because it tends to easily obtain better permanent shear stability. Here, the number average molecular weight is measured by gel permeation chromatography and is a value in terms of polystyrene.
The olefin copolymer preferably has a Mw / Mn ratio of 1.5 to 3.0, more preferably 1.6 to 2.5.
The olefin copolymer may be used alone or in combination of two or more, and when two or more are used in combination, the weight average molecular weight and number average molecular weight are within the above ranges. Preferably.

The blending amount of the olefin copolymer with respect to the total amount of the hydraulic fluid composition is preferably 0.1 to 5% by mass, more preferably 0.2 to 3% by mass, and still more preferably 0.3 to 2% by mass. is there. By setting the blending amount to 0.1% by mass or more, the viscosity index of the hydraulic fluid composition can be increased, the temporary shear viscosity under high shear conditions can be lowered, and the power saving effect based on the olefin copolymer can be obtained. Since it becomes easy, it is preferable. On the other hand, if the olefin copolymer is too much, the permanent shear stability is lowered, so the blending amount is preferably 5% by mass or less. If the olefin copolymer is too much, the compatibility with other additives, particularly fatty acid amides, is lowered, and in particular, the compatibility of the additives may be further lowered when the base oil is a paraffinic base oil. As a result, it may be difficult to sufficiently obtain the effect of the additive. Also in this respect, the blending amount of the olefin copolymer is preferably 5% by mass or less.

In the hydraulic fluid composition of the present invention, in order to increase the power saving effect by blending poly (meth) acrylate or olefin copolymer and lowering the high shear viscosity, the poly (( It is preferable to contain both (meth) acrylate and an olefin copolymer having a specific weight average molecular weight at a predetermined content. In other words, low molecular weight poly (meth) acrylates and olefin copolymers have excellent permanent shear stability, but are less likely to decrease in viscosity against temporary shear, and have little effect on increasing the viscosity index of a hydraulic fluid composition. Therefore, the contribution to power saving performance tends to be low. Conversely, high molecular weight poly (meth) acrylates and olefin copolymers can increase the viscosity index and decrease in viscosity with respect to temporary shear, but tend to have poor permanent shear stability.

On the other hand, when comparing poly (meth) acrylates and olefin copolymers of the same molecular weight, poly (meth) acrylates are easier to increase the viscosity index, have excellent compatibility with additives, and the effects of additives such as wear resistance are sufficient. Has the advantage of being easily pulled out, but tends to be inferior in permanent shear stability. On the contrary, the olefin copolymer has an advantage of excellent balance between the temporary shear viscosity reduction rate and the permanent shear stability, but tends to be inferior in compatibility with the additive. Therefore, it is difficult to satisfy all of high viscosity index, temporary shear viscosity reduction, permanent shear stability, and compatibility with additives alone, either by poly (meth) acrylate or olefin copolymer alone. By including both an average molecular weight poly (meth) acrylate and a specific weight average molecular weight olefin copolymer, all of the required performances can be satisfied.
In order to achieve the above performance, the content ratio of the component (d) and the component (e) is preferably in the range of 10 to 1000 parts by mass of the component (e) with respect to 100 parts by mass of the component (d), and 20 to 500 parts. The range of parts by mass is more preferable.

(F) Demulsifier In the hydraulic fluid composition of the present invention, in addition to the above (b) fatty acid, (c) fatty acid amide, (d) poly (meth) acrylate, and (e) olefin copolymer, various hydraulic equipment as a whole In order to further enhance the power saving effect, it is preferable to further contain (f) a demulsifier. This is to prevent a decrease in wear resistance and a decrease in power saving effect due to the oil film being cut when moisture is mixed, by improving the separation of moisture.

(F) As a demulsifier, a nonionic surfactant is preferable. As the nonionic surfactant, polyalkylene glycol is preferable. Specific examples of the polyalkylene glycol as the main component include homopolymers obtained by polymerizing ethylene glycol, propylene glycol or butylene glycol as monomers, and copolymers obtained by polymerizing these in combination. The homopolymer and copolymer may be used alone or in combination of two or more. As the nonionic surfactant, a copolymer is preferable, and an ethylene oxide-propylene oxide copolymer obtained by polymerizing a combination of ethylene glycol and propylene glycol is particularly preferable. The molecular weight of the surfactant is preferably from 100 to 20,000, particularly preferably from 1,000 to 15,000. In the case of the ethylene oxide-propylene oxide copolymer as the main component, the molar ratio of ethylene oxide: propylene oxide is preferably 10: 1 to 1:20, and particularly preferably 5: 1 to 1:10.

  The content of the (f) demulsifier in the hydraulic fluid composition of the present invention is preferably from 5 to 95 ppm by mass, particularly preferably from 10 to 80 ppm by mass, based on the total amount of the hydraulic fluid composition. By setting the content of (f) demulsifier in the hydraulic fluid composition of the present invention to 5 ppm by mass or more, it is easy to obtain a good effect. However, even if it exceeds 95 mass ppm, improvement in the effect commensurate with the amount added cannot be expected, and if the balance of the blending amount of (b) fatty acid and (c) fatty acid amide is not appropriate, emulsification is reversed. Therefore, the content is preferably 95 ppm by mass or less. From this point of view, when (f) a demulsifier is contained, the ratio of the content of (f) demulsifier to the total content of (b) fatty acid and (c) fatty acid amide is {(b) + (C)} :( f) = 100: 1 to 10: 1 (mass ratio) is preferable, and {(b) + (c)} :( f) = 80: 1 to 20: 1 (mass ratio) is preferable. Particularly preferred.

(G) Other Additives The hydraulic fluid composition of the present invention can contain various known additives as necessary within a range that does not impair the object of the present invention. Examples thereof include antioxidants, extreme pressure agents, antiwear agents, oiliness agents, detergent dispersants, ashless dispersants, rust inhibitors, metal deactivators, pour point depressants, and antifoaming agents.

Antioxidants include monocyclic rings such as 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, etc. Phenolic antioxidants, 4,4′-bis (2,6-di-t-butylphenol), 4,4′-methylenebis (2,6-di-t-butylphenol), 4,4′-ethylenebis ( 2,6-di-t-butylphenol), 4,4'-butylenebis (2,6-di-t-butylphenol), 6,6'-methylenebis (2-di-t-butyl-4-methylphenol), etc. -Containing bisphenol antioxidants, sulfur content such as 4,4′thiobis- (2,6-di-tert-butyl-phenol), 4,4′thiobis- (2-methyl-6-tert-butyl-phenol) Phenolic antioxidant, Alky Examples thereof include amine-based antioxidants such as diphenylamine and alkylated phenyl-α-naphthylamine, and phosphorus-based antioxidants such as phosphonic acid esters.

Examples of extreme pressure agents include sulfur-based extreme pressure agents such as sulfurized olefins, polysulfides, sulfurized fats and oils, dithiophosphoric acid derivatives, and organometallic extreme pressure agents such as ZnDTP and ZnDTC. Particularly preferred are sulfurized olefins and dithiophosphoric acid derivatives, and specific examples include β-dithiophosphorylated propionic acid.

Examples of the antiwear agent include phosphate esters and phosphites, and derivatives thereof. Specific examples of phosphate esters and phosphites include tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, dicresyl phenyl phosphate, tripropyl phosphate, tributyl phosphate, tri (2-ethylhexyl) phosphate , Dioctyl phosphate, monooleyl phosphate, dioleyl phosphite, diphenyl phosphite, tricresyl phosphite, trixylenyl phosphite and the like. These derivatives include amine salts such as stearylamine salts, oleylamine salts, and coconut amine salts.
Examples of the oily agent include higher alcohols such as oleyl alcohol, amines such as oleylamine, esters such as butyl stearate, and polyhydric alcohol half esters such as glycerin monooleate.

Examples of the cleaning dispersant include alkaline earth metal cleaning dispersants, and specific examples include Ca salicylate, Ca phenate, and Ca sulfonate.
Examples of the ashless dispersant include succinimide compounds, specifically, polybutenyl bissuccinimide and boron-modified compounds thereof.
Rust inhibitors include metal soaps such as sulfonate metal salts and naphthenic acid metal salts, alkyl succinic acid derivatives, alkenyl succinic acid derivatives, lanolin compounds, surfactants such as sorbitan monooleate and pentaerythritol monooleate, wax and Oxidized wax, petrolatum, N-oleylsarcosine, rosinamine, alkylated amine compounds such as dodecylamine and octadecylamine, fatty acids such as oleic acid and stearic acid, phosphorus compounds such as phosphite, etc. Acid derivatives, alkenyl succinic acid derivatives, surfactants, and alkylated amine compounds are preferably used, and alkyl succinic acid derivatives and alkenyl succinic acid derivatives are more preferable.

As the metal deactivator, benzotriazole and its derivatives, indazole and its derivatives, benzimidazole and its derivatives, indole and its derivatives, thiadiazole and its derivatives, etc. are used, benzotriazole and its derivatives, thiadiazole and its derivatives Is preferably used.
Examples of the pour point depressant include polyalkyl methacrylate, polybutene, polyalkyl styrene, polyvinyl acetate, polyalkyl acrylate and the like. The pour point depressant poly (meth) acrylate has a low molecular weight, preferably has a weight average molecular weight of less than 70,000, more preferably 65,000 or less, and 60,000 or less. More preferably. Further, the number average molecular weight of the poly (meth) acrylate as the pour point depressant is preferably less than 30,000, and more preferably 25,000 or less.
Examples of the antifoaming agent include silicone-based antifoaming agents such as dimethyl silicone, alkyl-modified silicone, phenyl-modified silicone, and fluorine-modified silicone, and polyacrylate-based antifoaming agents.

(H) Property of composition The hydraulic fluid composition of the present invention has a kinematic viscosity at 40 ° C. within the range conforming to any one of ISO VG10, 15, 22, 32, 46, 68, and 100. JIS K2283 kinematic viscosity test In the method, it is preferably 9.00 to 110 mm ² / s.
It 40 ° C. kinematic viscosity of the hydraulic fluid composition of the present invention is more preferably 18~100mm ² / s, more preferably from 25~75mm ² / s, a 40~51mm ² / s Is particularly preferred.

The viscosity index of the hydraulic fluid composition of the present invention is not particularly limited, but is preferably 120 or more, more preferably 130 or more, and further preferably 140 or more in the JIS K2283 kinematic viscosity test method. By setting the viscosity index to 120 or more, the low-temperature viscosity becomes low, so that it is easy to suppress the power consumption at the time of low-temperature start and tends to obtain a higher power saving effect.

The flash point of the hydraulic fluid composition of the present invention is preferably 200 ° C. or higher, more preferably 250 ° C. or higher. A flash point of 250 ° C. or higher is preferred because it is designated as a “flammable liquid” in the dangerous goods classification under the Fire Service Law, and the storage and handling regulations are greatly relaxed. The flash point of the hydraulic fluid composition is such that the initial distillation point in GC distillation of the base oil (or base oil after mixing when a plurality of base oils are used) is 350 ° C. or higher and the 5% distillation temperature is 380 ° C. By setting it as ℃ or more, it is easy to ensure 250 ℃ or more.

(I) Applications The hydraulic fluid composition of the present invention can be applied to various industrial hydraulic fluids, but can be preferably used as a hydraulic fluid used in a hydraulic system. Furthermore, it is especially effective when there are sliding parts between metals such as a vane pump in a hydraulic system, or when wear resistance is required due to high pressure, and you want to reduce the friction loss of these sliding parts. It is.
Furthermore, the hydraulic fluid composition using the poly (meth) acrylate as the component (d) and the olefin copolymer as the component (e) in combination with many hydraulic pipes, various filters, various control valves, etc. , Hydraulic pumps, hydraulic motors, control valves, etc., especially effective for power saving in places where hydraulic oil is exposed to high shear conditions. This is effective for saving power.

Next, the present invention will be described more specifically with reference to examples. In addition, this invention is not restrict | limited at all by these examples. The base oil and additive components used in the preparation of the hydraulic fluid composition in each example and comparative example are as follows.

<Base oil>
・ Hydrocracked mineral oil A: Indonesian paraffin-based crude oil is used as the raw material, the residual oil obtained by atmospheric distillation is distilled under reduced pressure, and then the fraction obtained as a lubricating oil fraction is hydrocracked and again decompressed. A mineral oil obtained by distillation and hydrofinishing after wax distillation and has the properties shown in Table 1.
・ Hydrocracked mineral oil B: Middle oil-derived paraffinic crude oil as a raw material, after the residual oil obtained by atmospheric distillation was distilled under reduced pressure, the fraction obtained as a lubricating oil fraction was hydrocracked and again decompressed A mineral oil obtained by distillation and hydrofinishing after wax distillation and has the properties shown in Table 1.

<Friction modifier>
Friction modifier A: oleic acid Friction modifier B: Isostearic acid Friction modifier C: Oleamide (R2 in Formula (1) is a hydrogen atom)
-Friction modifier D: Glycerol monooleate-Friction modifier E: Ditridecyl adipate (DTDA)
・ Friction modifier F: Isostearyl alcohol

<Performance additive>
Non-Zn hydraulic oil PKG (package): Contains amine antioxidant, phosphorus-sulfur-containing extreme pressure agent, fatty acid rust inhibitor, thiadiazole derivative.
Dispersant: polybutenyl-bissuccinimide (the weight average molecular weight of the two polybutenyl groups is 1300, and the nitrogen content is 1.8% by mass)
・ Demulsifier: Ethylene oxide-propylene oxide copolymer (ethylene oxide: propylene oxide = 1: 4 (molar ratio))
・ Phosphorus antiwear agent: tricresyl phosphate ・ Antifoaming agent: Dimethyl silicone ・ Rust inhibitor: Alkenyl succinic acid half ester ・ Phenol antioxidant: Di-t-butyl-p-cresol ・ Pour point depressant: Poly (meth) acrylate (Mw: 51,000, Mn: 28,000, Mw / Mn = 1.82)

<Viscosity index improver>
OCP: non-dispersed olefin copolymer (ethylene / propylene copolymer), weight average molecular weight 16,000, number average molecular weight 7000, ethylene / propylene molar ratio: 10/9, active ingredient amount 100% by mass.
PMA: non-dispersed poly (meth) acrylate viscosity index improver, weight average molecular weight 140,000, number average molecular weight 50,000, active ingredient amount 60% by mass.

The physicochemical property tests of the base oil and hydraulic fluid compositions shown in Tables 1 to 5 were performed by the test methods shown below.
·density
: JIS K 2249 “Density Test Method”
・ Kinematic viscosity
: JIS K 2283 "Kinematic viscosity test method"
・ Viscosity index
: JIS K 2283 "Viscosity index calculation method"
・ Pour point
: JIS K 2269 "Pour point test method"
·Flash point
: JIS K 2265-4 "Flash point test method (Cleveland open method)"
・ Residual carbon
: JIS K 2270 “Residual carbon content test method”
・ Acid value
: JIS K 250.1 “Neutralization test method”
・ ASTM color
: JIS K 2580 “ASTM color test method”
・ Sulfur content (ultraviolet fluorescence method)
: JIS K 2541-6 “Sulfur content test method (ultraviolet fluorescence method)”
・ Nitrogen content
: JIS K 260.9 "Testing method for nitrogen content"

・ Ndm
: ASTM 3238-85 "Standard Test Method for Calculation of Carbon Distribution
and Structural Group Analysis of Petroleum Oils By the ndm Method "
-Aniline point: JIS K 2256 "Test method for aniline point and mixed aniline point"
・ Iodine value: JIS K 07.70 “Testing methods for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponified product of chemical products”
GC distillation temperature: JIS K 2254 “Distillation test method (gas chromatography method)”
-About absolute viscosity, it computed with the following formula | equation. In addition, the density and kinematic viscosity in a formula were measured according to the said measuring method.
Absolute viscosity (40 ° C) = density (40 ° C) x kinematic viscosity (40 ° C)

The performance evaluation tests of the hydraulic fluid compositions shown in Tables 2 to 5 were performed by the following test methods.
・ Solubility at the time of preparation: A predetermined amount of all the substrates were put into a beaker, and the dissolution state of the composition immediately after preparation at a temperature of 60 ° C. for 1 hour was observed. The observation results are indicated by the following symbols.
○: No turbidity, clear dissolution △: Slight turbidity is observed
×: not dissolved or cloudy

Storage stability: About 90 ml of the sample was injected into a 100 ml sample tube, stored at room temperature and 0 ° C. for 1 week, and observed for turbidity / precipitation / discoloration. The observation results were evaluated with the following symbols.
○: No turbidity / precipitation / discoloration, clear dissolution △: Slight turbidity, precipitation / discoloration x: Obvious turbidity, precipitation / discoloration

SRV friction test: A friction test was performed under the following conditions using an "SRVIII" tester manufactured by Optimol Co., Ltd., and the coefficient of friction after 30 minutes was evaluated.
(Test conditions)

Temperature: 40 ° C

Load: 100N

Frequency: 50Hz

Amplitude: 1 mm
The lower the coefficient of friction obtained by the SRV friction test, the better. 0.155 or less is preferable, 0.150 or less is more preferable, 0.145 or less is more preferable, and 0.142 or less is particularly preferable.

表２中の粘度指数向上剤の含有量（質量％）を示す数値において、括弧内は希釈油を除く有効成分量である。

In the numerical values indicating the content (mass%) of the viscosity index improver in Table 2, the amount in parentheses is the amount of active ingredient excluding diluent oil.

表３中の粘度指数向上剤の含有量（質量％）を示す数値において、括弧内は希釈油を除く有効成分量である。

In the numerical values showing the content (mass%) of the viscosity index improver in Table 3, the amount in parentheses is the amount of active ingredient excluding diluent oil.

表４中の粘度指数向上剤の含有量（質量％）を示す数値において、括弧内は希釈油を除く有効成分量である。

In the numerical values indicating the content (mass%) of the viscosity index improver in Table 4, the amount in parentheses is the amount of active ingredient excluding diluent oil.

表５中の粘度指数向上剤の含有量（質量％）を示す数値において、括弧内は希釈油を除く有効成分量である。

In the numerical values indicating the content (mass%) of the viscosity index improver in Table 5, the amount in parentheses is the amount of active ingredient excluding diluent oil.

For the hydraulic fluid compositions shown in Tables 2 to 5, the following performance tests were further performed under the following test conditions. The results are shown in Tables 6-8.
Thermal oxidation stability test: 40 ml of a sample is put in a glass container having an inner diameter of 2.5 cm, a steel and copper catalyst is immersed, and left in a thermostatic bath with a rotating plate at 140 ° C., and the amount of sludge after 240 h (0 .8 μm Millipore filter used).
(Catalyst material / size)
Steel = SPCC-SB, Copper = C1100P, both sizes are 1.0mm x 20mm x 50mm
Demulsibility: Demulsibility was evaluated in accordance with JIS K 2520 “Water Separation Test Method 5. Demulsibility Test Method”. The evaluation results are shown as follows.
Oil layer-water tank-emulsified layer (elapsed time) = OW-E (min)

High shear viscosity: USV (Ultra Shear Viscometer, manufactured by PCS Instruments) was used to measure the shear viscosity at a temperature of 40 ° C. and a shear rate of 10 ⁶ (S ⁻¹ ).
-Primary shear viscosity reduction rate: High shear viscosity was measured by the above-mentioned apparatus and conditions, and the primary shear viscosity reduction rate was calculated from the following formula.
Primary shear viscosity reduction rate = (high shear viscosity (40 ° C.) − Absolute viscosity (40 ° C.)) / (Absolute viscosity (40 ° C.)) × 100

Vickers 104c pump test: ASTM D 7043-10 “Standard Test Method for Indicating Wear Characteristics of Non-Petalum and Petroleum Fluid Fluid in a Con V The amount was evaluated.

As shown in Table 2, Table 3 and Table 6, Examples 1 to 6 satisfying the constitution of the present invention are excellent in solubility at the time of preparation, storage stability at room temperature and 0 ° C., and 0.155 in the SRV test. The following low coefficient of friction is shown. In addition, the amount of sludge in the thermal oxidation stability test is as good as 1.0 mg / 40 ml or less, and the demulsibility is also good within 30 minutes. In addition, all have low high shear viscosity which is an effect by OCP and PMA.
Further, as shown in Table 8, in Example 1, the amount of wear in the Vickers 104c pump test also cleared the acceptance criteria of the hydraulic fluid standard JCMAS HK (JCMAS P041: 2004) for construction machinery, and further the German Industrial Standard DIN51524. -2 (Abrasion Resistant Hydraulic Fluid Standard) The required performance of HLP46 is greatly exceeded, and it can be seen that the hydraulic fluid has good performance.

On the other hand, as shown in Table 4, Table 5, and Table 7, Comparative Examples 1 to 8 that do not satisfy the configuration of the present invention are solubility at the time of preparation, storage stability at room temperature and 0 ° C., SRV friction coefficient, thermal oxidation. It turns out that it is inferior compared with an Example in either stability or demulsibility.
That is, Comparative Examples 1 and 2, which do not contain a friction modifier, are excellent in solubility at the time of preparation, storage stability at room temperature and 0 ° C., thermal oxidation stability, and demulsibility are also good, but SRV test The friction coefficient at is high. In addition, the comparative example 1 which does not contain OCP and PMA also has a high high shear viscosity.

Comparative Example 3, which contains only fatty acids as a friction modifier, and whose blending amount is larger than the blending amount of the examples, is inferior in storage stability (discolored at room temperature), has a slightly higher friction coefficient, thermal oxidation stability and resistance. The emulsifiability is also inferior, and Comparative Example 4 containing only fatty acid amide has a low friction coefficient, but is inferior in storage stability at 0 ° C. and demulsibility. Further, Comparative Example 5 containing glycerin monooleate, which is a kind of polyhydric alcohol half ester as a friction modifier, has a low friction coefficient but is poor in storage stability at 0 ° C.
Further, Comparative Example 6 combining fatty acid amide and DTDA which is a dibasic acid ester has a low friction coefficient but poor storage stability at 0 ° C., and is a comparative example combining fatty acid amide and isostearyl alcohol which is an aliphatic alcohol. 7 has a slightly higher coefficient of friction and inferior storage stability at 0 ° C.

Although the hydraulic fluid composition of the present invention can be applied as various industrial lubricating oils, it can be preferably used particularly as a hydraulic fluid used in a hydraulic system.

Claims (4)

(A) at least one base oil selected from mineral oil and / or synthetic oil,
(B) 0.02-0.8 % by mass of fatty acid,
(C) 0.01 to 1.0% by mass of a fatty acid amide selected from the fatty acid monoamide represented by the following general formula (1) and the fatty acid bisamide represented by the following general formula (2),
A hydraulic fluid composition characterized by containing (however, having a mesogenic structure in the molecule, a viscosity-pressure coefficient at 40 ° C. of 20 GPa ⁻¹ or less, and friction with increasing pressure under a pressure of 10 MPa or more. Excluding those containing at least one organic compound that develops the minimum value of the coefficient) .

(R ₁ , R ₃ and R ₅ in the general formula (1) and the general formula (2) represent a linear or branched aliphatic hydrocarbon group having 6 to 24 carbon atoms, and R ₂ represents a hydrogen atom or carbon. A straight or branched aliphatic hydrocarbon group having 1 to 24 carbon atoms is represented, and R ₄ represents a straight or branched divalent aliphatic hydrocarbon group having 1 to 6 carbon atoms.) The hydraulic fluid composition according to claim 1, wherein R ₂ in the general formula (1) is a hydrogen atom or a methyl group. (D) 0.06-3 mass% of poly (meth) acrylate having a weight average molecular weight of 70,000 to 200,000,
(E) 0.1-5 mass% of olefin copolymers with a weight average molecular weight of 5000-100,000 are contained, The hydraulic fluid composition of Claim 1 or 2 characterized by the above-mentioned. The hydraulic fluid composition according to any one of claims 1 to 3, wherein (f) a demulsifier is contained in an amount of 5 to 95 mass ppm.