JP5202850B2 - Hydrous lubricating oil composition and pH stabilizer used therefor - Google Patents

Description

  The present invention relates to a water-containing lubricating oil composition that has both good property stability and excellent flame retardancy over a long period of time, such as a water-containing lubricating oil pH stabilizer or a kinematic viscosity stabilizer. It relates to the property stabilizer of

  Hydraulic equipment is widely adopted in the industry and contributes to productivity improvement. In these hydraulic systems, hydraulic fluid is used as a power transmission medium, but water-glycol hydraulic fluid and other fluids have been used for disaster prevention in the vicinity of high-temperature heat sources and equipment that generates electric sparks. Various hydrous hydraulic fluids are used.

There is little change in the liquid property of the hydraulic fluid with respect to heat and shear, and it is desired to maintain the property within an appropriate range for a long period of time and to maintain the performance.
For example, water-glycol based hydraulic fluid has excellent performance, but it can be used while maintaining the performance by controlling the properties of the fluid such as pH and kinematic viscosity (JIS K2234) by replenishing the concentrate. It is common to do. For this reason, in the use of a water-glycol hydraulic fluid, it is a problem that labor and cost are required for maintenance and performance maintenance, and reduction of labor by extending the life of the fluid is required.

  Examples of techniques for improving the performance of hydrous lubricating oil include polyoxyalkylene glycol diether compounds having a specific structure, polyoxyalkylene glycol monoether compounds having a specific structure, polyoxypropylene glycol monoether compounds having a specific structure, and fatty acids having a specific structure. A water-containing lubricating oil composition containing a salt (see Patent Document 1), a water-glycol flame-retardant hydraulic fluid containing a neutralized product of glycerol borate and a base (see Patent Document 2), a water structure having a specific structure Water-glycol flame retardant hydraulic fluid containing a reactive polyether (see Patent Document 3) and the like, and these inventions focus on sustaining lubricity and wear resistance.

It has also been proposed to use aminotetrazole and water-soluble salts thereof as water-soluble iron anticorrosives (see Patent Document 4). However, the present invention is an invention aimed at preventing the occurrence of rust at a low concentration, and is characterized by the combined use of alkenyl succinic acid and its derivatives.

Japanese Patent No. 3323490 Japanese Patent No. 2646308 Japanese Patent Laid-Open No. 7-23391 JP 2000-26982 A

The present invention has been made in view of the circumstances of the prior art, for a long period of use of the water-based lubricant, pH stabilizer making it possible to reduce the maintenance and containing the same excellent A hydrous lubricating oil composition having high pH stability is also provided.

As a result of intensive studies to solve the above problems, the present inventor has found that an aminotetrazole compound or a salt thereof has an excellent pH stabilizing function, and has completed the present invention. Moreover, it came to complete the long-life water-containing lubricating oil composition by mix | blending an aminotetrazole type compound or its salt.
That is, the present invention provides a pH stabilizer for hydrous lubricating oil containing 30 to 50% by mass of water containing the aminotetrazole compound represented by the general formula (1) or a salt thereof as an active ingredient. is there.

(In the formula, R ¹ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ² and R ³ are a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkanol group.)
Further, in the above pH stabilizer, in which R ^1, R ² and R ³ in the general formula (1) provides a pH stabilizer are all hydrogen atoms.
The present invention also provides a pH stabilizer for the water-containing lubricating oil used in the above-mentioned pH stabilizer.
The present invention also provides a pH stabilizer, wherein the glycol contained in the water-glycol hydraulic fluid is propylene glycol, dipropylene glycol or a mixture thereof.

Moreover, this invention is 0.02-0.1 mass% in conversion of the amount of aminotetrazole type compounds about the pH stabilizer which uses the aminotetrazole type compound or its salt represented by General formula (1) as an active ingredient. And a water-containing lubricating oil composition characterized by containing 30 to 50% by mass of water .
In addition, the present invention provides a water-containing lubricating oil composition that further contains an alkali metal or alkaline earth metal hydroxide.
The present invention also provides a water-containing lubricating oil composition comprising 5 to 40% by mass of a thickener comprising a water- soluble polyoxyalkylene polyol or an alkyl ether derivative thereof in the water- containing lubricating oil composition. is there.

Further, the present invention provides the water-containing lubricating oil composition, wherein the polyoxyalkylene polyol is an ethylene oxide homopolymer, an ethylene oxide / propylene oxide copolymer, or a polyhydric alcohol with an ethylene oxide homopolymer, ethylene oxide, and The present invention provides a water-containing lubricating oil composition which is a compound obtained by adding a copolymer of propylene oxide or a copolymer of ethylene oxide and another alkylene oxide.
The present invention also provides a water-containing lubricating oil composition, wherein the water-containing lubricating oil composition is a water-glycol-based hydraulic fluid composition.

The water-containing lubricating oil composition of the present invention is excellent in pH stability and can reduce maintenance over a long period of use. In addition to the water glycol-based hydraulic fluid, the water-containing lubricating oil composition is the same for W / O emulsion type, O / W emulsion type hydraulic fluid, rolling oil, forging oil, drawing oil, and cutting oil. Can be expected.

The aminotetrazole compound or a salt thereof used in the present invention is a compound represented by the general formula (1). In the formula, R ¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Examples of R ¹ include a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a 1-methylpropyl group, a 2-methylpropyl group, and a t-butyl group. In the formula, R ² and R ³ represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or an alkanol group, and R ² and R ³ may be the same or different. Examples of R ² and R ³ include a hydrogen atom, methyl group, ethyl group, propyl group, isopropyl group, 1-methylpropyl group, 2-methylpropyl group, t-butyl group and one of each alkyl group. And an alkanol group in which the hydrogen atom is substituted with a hydroxyl group.
At least one of R ¹ , R ² and R ^{3 in} the general formula (1) is preferably a hydrogen atom, more preferably two or more are hydrogen atoms, and more preferably three are hydrogen atoms. Particularly preferred. Further, when R ^1, R ² or R ³ in the general formula (1) is an alkyl group or an alkanol group having 1 to 4 carbon atoms is preferably an alkyl group or an alkanol group having 1 to 3 carbon atoms, The alkyl group or alkanol group having 1 to 2 carbon atoms is more preferable, and the alkyl group or alkanol group having 1 carbon atom is particularly preferable.

Examples of the salt of the aminotetrazole-based compound salt include alkali metal salts such as sodium salt and potassium salt, metal salts such as alkaline earth metal salts such as calcium salt, monoethanolamine salt, diethanolamine salt, triethanolamine salt, and isopropanol. Examples thereof include alkanolamine salts such as amine salts, ammonium salts, and alkylammonium salts.

The content of the aminotetrazole-based compound may be appropriately selected, but is preferably 0.001 to 1% by mass, more preferably 0.05 to 0.5% by mass, and particularly preferably 0. It is 02-0.1 mass%. When the content is small, there is a problem that a sufficient addition effect cannot be obtained, and when it exceeds 1% by mass, an addition effect corresponding to the addition amount cannot be obtained, which is not preferable.
Moreover, when using an aminotetrazole type compound salt, an aminotetrazole type compound salt may be appropriately contained so that the amount of the aminotetrazole type compound becomes the above amount.
Moreover, you may use together an aminotetrazole type compound and its salt, and what is necessary is just to adjust content so that the total amount may become the said amount of an aminotetrazole type compound.

The appropriate amount varies within the above range depending on the inclusion of other additives and the like, but in a hydrous lubricating oil composition containing an aminotetrazole compound or a salt thereof, JIS K2514 (Lubricating oil oxidation stability test method) In the life evaluation test using the test device specified in item 6 (Rotating cylinder type oxidation stability test method)), it is possible to select an addition amount that reduces the amount of change in pH, kinematic viscosity, etc. before and after the test. . The test conditions for this test are, for example, the amount of test solution: 80 g, catalyst; none, test temperature: 120 ° C., sealed oxygen pressure: 620 kPa (@ 25 ° C.), test time: 24 Hr.
When the above test conditions are used, the amount of change in pH is within ± 25%, preferably within ± 15%, particularly preferably within ± 8% before and after the test, or the change in kinematic viscosity at 40 ° C. is within the test. Before and after, it may be added so that it is within ± 25%, preferably within ± 15%, particularly preferably within ± 5%.
As described above, the aminotetrazole-based compound or a salt thereof exhibits excellent performance as a property stabilizing additive such as a pH stabilizer and a kinematic viscosity stabilizer.

In addition, the present invention is a water-containing lubricating oil composition containing an aminotetrazole compound or a salt thereof capable of obtaining such a test result.
The hydrous lubricating oil composition of the present invention can be applied to various hydrous lubricating oils, but can be suitably applied to water-glycol hydraulic fluids.
A hydrous lubricating oil such as a water-glycol hydraulic fluid contains water. The water content, Ru 30-50% by mass. Examples of glycols contained in the water-glycol hydraulic fluid include glycols such as ethylene glycol, diethylene glycol, trimethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, hexylene glycol, and dihexylene glycol. The monoalkyl ether of these glycols is mentioned. Here, as for carbon number of the alkyl group in monoalkyl ether, 1-8 are preferable. These glycols may be used alone or in combination of two or more. Usually, it is preferable to use propylene glycol or dipropylene glycol. Content of glycols should just be 20-60 mass%, Preferably it is 25-50 mass%.

In the water-containing lubricating oil composition of the present invention, it is preferable to further blend an alkali metal or alkaline earth metal hydroxide, and more preferably blend an alkali metal hydroxide. As an alkali metal, lithium, sodium, and potassium are preferable, and sodium and potassium are more preferable. As the alkaline earth metal, magnesium, calcium and barium are preferable, and calcium is more preferable.
By blending the aminotetrazole-based compound or a salt thereof and these components, excellent property stabilization properties such as excellent pH stabilization property or kinematic viscosity stabilization property for a hydraulic fluid adjusted to a desired pH can be exhibited. .
The content of alkali metal or alkaline earth metal hydroxide is preferably 0.05 to 1% by mass, particularly preferably 0.1 to 0.5% by mass.

  In the water-containing lubricating oil composition of the present invention, in addition to blending the aminotetrazole-based compound or aminotetrazole-based compound with an alkali metal or alkaline earth metal hydroxide, the water-containing lubricating oil composition is usually used for a water-containing lubricating oil. Any of the components can be used.

In the hydrous lubricating oil composition of the present invention, it is preferable to add a thickener.
As the thickener, a water-soluble polyoxyalkylene polyol or an alkyl ether derivative thereof can be used. Specifically, water-soluble ethylene oxide (EO) homopolymer, EO / propylene oxide (PO) copolymer, polyhydric alcohol with EO homopolymer, EO and PO copolymer or EO and other Examples thereof include compounds obtained by adding a copolymer with an alkylene oxide (for example, 1,2-butylene oxide, tetrahydrofuran, α-olefin oxide, etc.), or alkyl ether derivatives thereof. 1-4 are preferable and, as for carbon number of the alkyl group in the alkyl ether group in this alkyl ether derivative, 1-3 are especially preferable.

Specific examples of the water-soluble polyoxyalkylene polyols include polyoxyalkylene glycol, polyoxyalkylene triol, polyoxyalkylene glycol monoether, polyoxyalkylene glycol diether and the like.
When using a copolymer of EO and another alkylene oxide, or a copolymer of EO and another alkylene oxide as an adduct to a polyhydric alcohol, the other alkylene oxide is preferably PO, The molar ratio of EO / other alkylene oxide is preferably 25/75 to 80/20. If the molar ratio of EO is too small, the solubility in the working fluid may be insufficient. Further, the addition mode of EO and other alkylene oxide copolymers may be random addition or block addition.

The average molecular weight of the water-soluble polyoxyalkylene polyols is preferably in the range of 1,000 to 20,000. When the average molecular weight is lower than 1,000, the original thickening effect is small and it is necessary to increase the blending amount. Therefore, the blending ratio of glycols is relatively decreased and the solubility of the system is changed. Therefore, it is not preferable. On the other hand, if the molecular weight exceeds 20,000, the stability of the thickener against heat and shear may be impaired, and the change in properties when the thickener is decomposed is not preferred.
Content of a thickener should just be 5-40 mass%, Preferably it is 10-30 mass%.

The hydrous lubricating oil composition of the present invention preferably has a 40 ° C. kinematic viscosity of 19.8 to 74.8 mm ² / sec, particularly preferably 28.8 to 50.6 mm ² / sec.
The water-containing lubricating oil composition of the present invention includes a lubricant, a liquid phase rust preventive agent, a gas phase rust preventive agent, a metal deactivator, a pH adjuster, an antifoaming agent, a colorant, and other optional additives. Can be blended as needed.
Lubricants include saturated fatty acids such as caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid and stearic acid, unsaturated fatty acids such as oleic acid, linoleic acid and linolenic acid, aromatic fatty acids and dimer acids Etc. Moreover, these fatty acids may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  Examples of the liquid phase or gas phase rust preventive include alkylated morpholines such as morpholine, methylmorpholine, and ethylmorpholine, monoethanolamine, diethanolamine, triethanolamine, 3-amino-1-propanol, 1-amino-2-propanol, 3-methoxypropylamine, 3-ethoxypropylamine, ethylenediamine, diethylenetriamine, cyclohexylamine, N-methylethanolamine, N-methyldiethanolamine, N-ethylethanolamine, N-ethyldiethanolamine, Nn-butylethanolamine, N -n-butyldiethanolamine, dimethylethanolamine, diethylethanolamine, dibutylethanolamine, N- (β-aminoethyl) ethanolamine, 1,4-bis (2-hydroxyethyl) ) Imidazoline, hydroxyethyl piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, 2,6 organic amines and their derivatives such as dimethyl piperazine, and the like carboxylic acid alkali metal salt. These liquid phase or vapor phase rust preventives may be used alone or in combination of two or more.

  As the pH adjuster, in addition to the alkali metal hydroxides and alkaline earth metal hydroxides described above, those mentioned as the gas phase and liquid phase rust preventive agents can also be used. It is preferable to adjust the alkalinity of the hydraulic fluid to a desired pH by blending these pH adjusters. If the pH is too low, the solubility of the lubricant present in the liquid is insufficient and there is a risk of sludge formation. On the other hand, if the pH is too high, the wear resistance of the hydraulic fluid may be reduced.

Examples of the metal deactivator include benzotriazole compounds such as benzotriazole, tolyltriazole, 5-methylbenzotriazole, carboxybenzotriazole and alkali metal salts or amine salts thereof, mercaptobenzothiazole and alkali metal salts thereof. It is done.
Examples of the antifoaming agent include emulsions of silicone compounds, and examples of the coloring agent include alcohol-based coloring agents and metal-based coloring agents.

Hereinafter, 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.
(Evaluation of hydraulic fluid)
Regarding the stability of the hydraulic fluid, the life was evaluated using a rotary cylinder type oxidation stability tester. This tester is defined in item 6 of JIS K2514 (Lubricating oil oxidation stability test method). Evaluation was made based on changes in pH and kinematic viscosity of the solution after the test. The smaller the amount of change, the better the stability of the hydraulic fluid.
The test conditions are as follows.
Test solution volume: 80g
Catalyst; None Test temperature: 120 ° C
Enclosed oxygen pressure: 620 kPa (@ 25 ° C.)
Test time: 24 hours

(Examples 1-6 )
The components shown in Table 1 and Table 2 were mixed at the blending amounts shown in Table 1 and Table 2 to prepare a water-containing lubricating oil composition. It evaluated by the said test using the prepared water-containing lubricating oil composition. The evaluation results are shown in Tables 1 and 2. The aminotetrazole used in this example is 5-amino-1H-tetrazole in which R ¹ , R ² and R ³ in the general formula are all hydrogen atoms. Aminotetrazole previously dissolved in 20% by mass in 10% by mass potassium hydroxide aqueous solution was used.

(Comparative Examples 1-2)
The components shown in Table 3 were mixed at the blending amounts shown in Table 3 to prepare a water-containing lubricating oil composition. It evaluated by the said test using the prepared water-containing lubricating oil composition. The evaluation results are shown in Table 3.

In Tables 1 to 3, thickeners, glycols, metal deactivators, and lubricants are shown below.
Thickener A is polyoxyethylene / oxypropylene glycol, a random copolymer having an EO / PO molar ratio of 75/25, and an average molecular weight of 15,000. Thickener B is polyoxyethylene / oxypropylene glycol, a random copolymer having an EO / PO molar ratio of 75/25, and an average molecular weight of 5,000. Thickener C is polyoxyethylene / oxypropylene glycol, a random copolymer having a EO / PO molar ratio of 50/50, and an average molecular weight of 1,750.

The glycol is propylene glycol, and the lubricant is coconut fatty acid. A benzotriazole derivative was used as a metal deactivator.
About each Example and the comparative example, it adjusted so that 40 degreeC kinematic viscosity might be set to 48.0 mm < ² > / sec by 10.0 with the compounding quantity of an alkali agent, propylene glycol, and a thickener.

As shown in Tables 1 and 2, all examples according to the present invention showed excellent stability.

  The water-containing lubricating oil composition of the present invention can suppress a change in pH for a long period of time, can also suppress a change in kinematic viscosity for a long period of time, and can reduce labor required for maintenance of the water-containing lubricating oil composition. Therefore, it is extremely useful in the field of hydrous lubricating oil.

Claims (9)

A pH stabilizer for hydrous lubricating oil containing 30 to 50% by mass of water containing an aminotetrazole compound represented by the general formula (1) or a salt thereof as an active ingredient.

(In the formula, R ¹ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ² and R ³ are a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkanol group.) The pH stabilizer according to claim 1 , wherein R ¹ , R ² and R ^{3 in the} general formula (1) are all hydrogen atoms. The pH stabilizer according to claim 1 or 2, wherein the water-containing lubricating oil is used for a water-glycol hydraulic fluid. The pH stabilizer according to claim 3, wherein the glycol contained in the water-glycol hydraulic fluid is propylene glycol, dipropylene glycol or a mixture thereof. The pH stabilizer to aminotetrazole compound or the salt thereof according to claim 1, in aminotetrazole based compound amount in terms of, 0.02 to 0.1 wt%, and water 30 to 50 wt% A water-containing lubricating oil composition characterized by comprising. The water-containing lubricating oil composition according to claim 5 , further comprising an alkali metal or alkaline earth metal hydroxide. The water-containing lubricating oil composition according to claim 5 or 6 , further comprising 5 to 40% by mass of a thickener comprising a water-soluble polyoxyalkylene polyol or an alkyl ether derivative thereof. Polyoxyalkylene polyol is ethylene oxide homopolymer, ethylene oxide / propylene oxide copolymer, or polyhydric alcohol with ethylene oxide homopolymer, copolymer of ethylene oxide and propylene oxide or ethylene oxide and other alkylene oxide. The water-containing lubricating oil composition according to claim 7 , which is a compound obtained by adding a polymer. The water-containing lubricating oil composition according to any one of claims 5 to 8, wherein the water-containing lubricating oil composition is a water-glycol hydraulic fluid composition.