JP2014051650A - Water-containing hydraulic fluid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-containing hydraulic fluid having small pH decrease, excellent in oxidation stability with small pH decrease by inhibiting acid formation over long time use.SOLUTION: A water-containing hydraulic fluid contains 0.01 to 1 mass% of one or more kind selected from compounds represented by general formulae (1) and (2). The general formula (1): a compound in which each two nitrogen atoms in piperazine is substituted by Rand R, where Rand Rare hydrogen atoms or alkyl groups having 1 to 3 carbon atoms, and at least one of Rand Ris an alkyl group having 1 to 3 carbon atoms. The general formula (2): a compound in which a nitrogen atom in piperidine is substituted by R, where Ris a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

Description

  The present invention relates to a water-containing hydraulic fluid that suppresses acid generation over a long period of use, has a small pH drop, and is excellent in oxidation stability.

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. However, in the vicinity of high-temperature heat sources and equipment that generates electric sparks, various difficulties such as water-glycol hydraulic fluids are required for disaster prevention. Flammable water-containing hydraulic fluid is used.
It is desired that the water-containing hydraulic oil has little change in liquid properties with respect to oxidation and shear, and keeps its properties within an appropriate range over a long period of time and maintains its performance.

For example, water-glycol hydraulic fluid has excellent performance, but generation of acid and viscosity reduction occur due to shear and oxidation during use. In order to maintain the performance, the concentrate is generally replenished and used while controlling the properties of the solution such as the pH of the solution. For this reason, in the use of a water-glycol based hydraulic fluid, maintenance and performance maintenance are troublesome and costly, so that it is necessary that the pH is not easily lowered during use.

In addition, when the water-glycol hydraulic fluid exceeds its proper value during use and deteriorates excessively to the extent that it is not appropriate to manage it by replenishing the concentrate, the working fluid is usually discarded. Replace with new solution. At this time, it is best to extract the used liquid sufficiently and replace it with a new one after flushing, but the water glycol-based hydraulic fluid is often used in dangerous places such as near high-temperature heat sources. Since the machine piping is also complicated and the liquid replacement is costly, the used liquid is rarely removed completely. For this reason, it is inevitable that the remaining solution is mixed with the new solution, but the acid contained in the remaining solution lowers the pH of the replaced solution and acts as a catalyst to promote oxidation. It becomes a factor that accelerates deterioration. For this reason, it is necessary to suppress the pH drop of the water-glycol hydraulic fluid and improve the oxidation stability when the working solution is mixed with the new solution.

Examples of performance improvement technologies such as pH reduction suppression and oxidative stability improvement of water-containing hydraulic fluid include, for example, polyoxyalkylene glycol diether compounds having a specific structure, polyoxyalkylene glycol monoether compounds having a specific structure, and polyoxyalkylene having a specific structure. Water-containing hydraulic fluid containing a propylene glycol monoether compound and a fatty acid salt having a specific structure (see Patent Document 1), water containing a neutralized product of glycerol borate and a base
Glycol-based flame retardant hydraulic fluid (see Patent Document 2), water containing a water-soluble polyether having a specific structure-glycol-based flame retardant hydraulic fluid (see Patent Document 3), water containing an alkylated morpholine having a specific structure -Glycol flame retardant hydraulic fluid (
(See Patent Document 4).

Japanese Patent No. 3323490 Japanese Patent No. 2646308 JP 2000-26982 A JP 2007-39569 A

The present invention has been made in view of the above-described prior art, and suppresses acid generation over a long period of use, has a small pH drop, has excellent oxidation stability, and further contains an acid generated by deterioration. An object of the present invention is to provide a water-containing working fluid that does not greatly impair such effects even when a water-containing working fluid is mixed.

  As a result of intensive studies to solve the above problems, the present inventor has found that a specific amount of a compound having a specific structure is contained, thereby suppressing a decrease in pH of the aqueous hydraulic fluid and improving oxidation stability. The invention has been completed.

（式中、Ｒ^１及びＲ^２は水素原子又は炭素数１〜３のアルキル基であって、かつＲ^１及びＲ^２の少なくともいずれか一方が炭素数１〜３のアルキル基である。）

（式中、Ｒ^３は水素原子又は炭素数１〜３のアルキル基である。） That is, the present invention provides a hydrous working fluid characterized by containing 0.01 to 1% by mass of one or more selected from the compounds represented by the general formulas (1) and (2).

(In the formula, R ¹ and R ² are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and at least one of R ¹ and R ² is an alkyl group having 1 to 3 carbon atoms.)

(In the formula, R ³ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)

（式中、Ｒ^４は炭素数１〜３のアルキル基である。）
また、本発明は、上記含水系作動液において、ベンゾトリアゾール及びトリルトリアゾールの内の1種以上を０．０１〜１質量％含むことを特徴とする含水系作動液を提供するものである。
また、本発明は、上記含水系作動液が水―グリコール系作動液である含水系作動液を提供するものである。 The present invention also provides a water-containing working fluid characterized in that the water-containing working fluid contains 0.01 to 1% by mass of the compound represented by the general formula (3).

(In the formula, R ⁴ is an alkyl group having 1 to 3 carbon atoms.)
The present invention also provides a water-containing working fluid characterized in that the water-containing working fluid contains 0.01 to 1% by mass of one or more of benzotriazole and tolyltriazole.
The present invention also provides a water-containing working fluid in which the water-containing working fluid is a water-glycol working fluid.

  The water-containing hydraulic fluid of the present invention suppresses acid generation over a long period of use, has a small pH drop, is excellent in oxidation stability, and further contains a water-containing hydraulic fluid containing an acid generated by deterioration. However, this effect is not greatly impaired, and maintenance can be reduced over a long period of use.

（式中、Ｒ^１及びＲ^２は水素原子又は炭素数１〜３のアルキル基であって、かつＲ^１及びＲ^２の少なくともいずれか一方が炭素数１〜３のアルキル基である。）

（式中、Ｒ^３は水素原子又は炭素数１〜３のアルキル基である。） The hydrous hydraulic fluid of the present invention contains one or more selected from the compounds represented by the general formulas (1) and (2).

(In the formula, R ¹ and R ² are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and at least one of R ¹ and R ² is an alkyl group having 1 to 3 carbon atoms.)

(In the formula, R ³ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)

R ¹ and R ^{2 in} the general formula (1) are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and at least one of R ¹ and R ² is an alkyl group having 1 to 3 carbon atoms. . Examples of R ¹ and R ² include a hydrogen atom, a methyl group, an ethyl group, a propyl group, and an isopropyl group. R ¹ and R ² are more preferably both alkyl groups, both are alkyl groups, and at least one is particularly preferably a methyl group, and most preferably two are methyl groups. That is, N, N-dimethylpiperazine is most preferable as the compound of the general formula (1).
R ^{3 in the} general formula (2) represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Examples of R ³ include a hydrogen atom, a methyl group, an ethyl group, a propyl group, and an isopropyl group. R ³ is preferably an alkyl group, and R ³ is particularly preferably a methyl group. That is, N-methylpiperidine is most preferable as the compound of the general formula (2).

The content of the compounds of the general formulas (1) and (2) is preferably 0.01 to 1% by mass, more preferably 0.05 to 0.98% by mass with respect to the total amount of the water-containing hydraulic fluid. Especially preferably, it is 0.2-0.95 mass%. If the content is small, a sufficient addition effect cannot be obtained, and if it exceeds 1% by mass, the metal may be corroded. The water-containing hydraulic fluid of the present invention may contain only one type selected from the group consisting of the compound of general formula (1) and the compound of general formula (2), or may contain two or more types. . In the case of containing two or more kinds, the total content of the water-containing hydraulic fluid needs to be within the numerical range of the above content.

（式中、Ｒ^４は炭素数１〜３のアルキル基である。） The water-containing working fluid of the present invention can further contain a compound represented by the general formula (3). By containing the compound of the general formula (3), it becomes easier to obtain a higher pH reduction suppressing effect, and the amount of the expensive compounds of the general formulas (1) and (2) can be reduced.

(In the formula, R ⁴ is an alkyl group having 1 to 3 carbon atoms.)

R ^{4 in the} general formula (3) represents an alkyl group having 1 to 3 carbon atoms. Examples of R ⁴ include a methyl group, an ethyl group, a propyl group, and an isopropyl group. R ^{4 in the} general formula (3) is preferably an ethyl group. That is, N-ethylmorpholine is preferred as the compound of general formula (3).

The content of the compound of the general formula (3) is preferably 0.01 to 1% by mass, more preferably 0.05 to 0.90% by mass, particularly with respect to the total amount of the water-containing hydraulic fluid. Preferably it is 0.2-0.80 mass%. Inclusion of 0.01% by mass or more facilitates obtaining a higher pH lowering effect, but if it exceeds 1% by mass, the metal may be corroded, which is not preferable. The mass ratio of the content of the compound of the general formula (3) to the content of the compound of the general formula (1) and the compound of the general formula (2) is preferably 1/4 to 4, and 1/3 to 3 is preferable. More preferably, 1 / 2-2 are still more preferable.
In addition, the compound of General formula (3) may contain only 1 type, and may contain 2 or more types. In the case of containing two or more kinds, the total content of the water-containing hydraulic fluid needs to be within the numerical range of the above content.

The hydrous working fluid of the present invention can further contain benzotriazole or tolyltriazole. By containing these, metal corrosion can be suppressed.
Examples of tolyltriazole include 3-methyl-1-H-benzotriazole, 4-methyl-1-H-benzotriazole, 5-methyl-1-H-benzotriazole, 6-methyl-1-H-benzotriazole, etc. Is mentioned.
The content of benzotriazole and tolutoazole is preferably 0.01 to 1% by mass, more preferably 0.05 to 0.70% by mass, particularly preferably based on the total amount of the hydraulic fluid. Is 0.08 to 0.50 mass%. Inclusion of 0.01% by mass or more facilitates obtaining a higher corrosion prevention effect, but if it exceeds 1% by mass, an effect commensurate with the content cannot be obtained, which is not preferable. In addition, benzotriazole and tolyltriazole may contain any one type, and may use together or may contain both. When using together, it is preferable to make total content into the said range.

The hydrous hydraulic fluid of the present invention can be applied to various hydrous hydraulic fluids such as water glycol hydraulic fluid, W / O emulsion type and O / W emulsion type hydraulic fluid, but optimally applied to water glycol hydraulic fluid it can.
A hydrous working fluid such as a water-glycol working fluid contains water. The water content is preferably 30 to 60% by mass and more preferably 30 to 50% by mass with respect to the total amount of the hydrous working fluid. If the water content is less than 30% by mass, the flame retardancy that is the merit of the water-containing hydraulic fluid may not be sufficiently exhibited. Moreover, when the water | moisture content exceeding 60 mass% is included, the abrasion resistance which is the objective of this invention may be insufficient from the time of unused.

The water glycol based hydraulic fluid contains water and glycols in the liquid.
The glycols contained in the water glycol-based hydraulic fluid include glycols such as ethylene glycol, diethylene glycol, trimethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, hexylene glycol, dihexylene glycol, and the like. And monoalkyl ethers of glycols. 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 ethylene glycol, propylene glycol or dipropylene glycol. Content of glycols should just be 20-60 mass%, Preferably it is 25-50 mass%. The glycols may be used alone or in combination of two or more, but when two or more types are used in combination, the total content is preferably within the above range.

In the water-containing working fluid of the present invention, an alkali metal or alkaline earth metal hydroxide may be used as an alkaline agent for pH adjustment, and in that case, the content thereof is the whole of the water-containing working fluid. 0.05-1 mass% is preferable with respect to quantity, and 0.1-0.5 mass% is more preferable.
In the water-containing working fluid of the present invention, it is preferable to blend a thickener. As the thickener, a water-soluble polyoxyalkylene polyol or an alkyl ether derivative thereof can be used. Specifically, water-soluble ethylene oxide (hereinafter also referred to as EO) homopolymer, EO / propylene oxide (hereinafter also referred to as PO) copolymer, polyhydric alcohol with EO homopolymer, EO and PO. Copolymer or EO and other alkylene oxides (
For example, a compound obtained by adding a copolymer with 1,2-butylene oxide, tetrahydrofuran, α-olefin oxide or the like, or an alkyl ether derivative 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 a copolymer of EO and another alkylene oxide, or a copolymer of EO and another alkylene oxide is used as an adduct to a polyhydric alcohol, the other alkylene oxide is preferably PO. , EO /
The molar ratio of the other alkylene oxide is preferably 25/75 to 90/10, and more preferably 50/50 to 85/15. 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 weight average molecular weight of the water-soluble polyoxyalkylene polyols is preferably in the range of 3,000 to 75,000, and more preferably in the range of 10,000 to 55,000. When the weight average molecular weight is lower than 3,000, the original thickening effect is small and the amount needs to be increased. Therefore, the blending ratio of glycols is relatively reduced and the solubility of the system is reduced. Since it changes, it is not preferable. On the other hand, if the weight average molecular weight exceeds 75,000, the stability of the thickener against heat and shearing may be impaired, and the change in properties when the thickener is decomposed is not preferable. The weight average molecular weight is measured by gel permeation chromatography and is a value in terms of polystyrene.
The content of the thickener may be 5 to 40% by mass, preferably 10 to 30% by mass with respect to the total amount of the hydrous working fluid.

The water based hydraulic fluid, preferably 40 ° C. kinematic viscosity of 20.0 ~ 75.0mm ² / sec, particularly preferably 30.0~55.0mm ² / sec.
The hydrous working fluid of the present invention requires 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. It can be blended according to.
Examples of the lubricant include saturated fatty acids such as myristic acid, palmitic acid, lauric acid and stearic acid, unsaturated fatty acids such as oleic acid, linoleic acid and linolenic acid, aromatic fatty acids and dimer acids. Among these, it is preferable to use an unsaturated fatty acid having 14 to 22 carbon atoms, and it is more preferable to use an unsaturated fatty acid having 16 to 20 carbon atoms. By setting it to 14 or more carbon atoms, better lubricity can be easily obtained. Moreover, it is hard to precipitate a fatty acid by setting it as C22 or less, and it is easy to obtain better long-term storage stability.
These fatty acids may be used alone or in combination of two or more.

Examples of the liquid phase or gas phase rust preventive agent include morpholine, monoethanolamine, diethanolamine, and triethanol in addition to the compounds represented by the general formulas (1), (2), and (3) that are constituents of the present invention. Amine, 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, Nn-butyldiethanolamine, dimethylethanolamine, diethylethanolamine, dibutylethanolamine, N- (β-aminoethyl) ethanolamine 1,4-bis (2-hydroxyethyl) imidazoline, piperazine, hydroxyethylpiperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, organic amines such as 2,6-dimethylpiperazine and their derivatives, carboxylic acid alkali metal salts Etc. These liquid phase or gas phase rust preventives are 1
One species may be used alone, or two or more species may be mixed and used.

Examples of the pH adjuster include alkali metal compounds such as potassium hydroxide and sodium hydroxide in addition to those mentioned as the liquid phase and gas phase rust preventives. It is preferable to adjust the pH of the hydraulic fluid to about 8 to 11 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 water-containing working fluid may be lowered.
As the metal deactivator, in addition to benzotriazole and tolyltriazole, which are essential components of the present invention, benzotriazole compounds such as carboxybenzotriazole and alkali metal salts or amine salts thereof, mercaptobenzothiazole and alkali metal salts thereof Etc.
Examples of the antifoaming agent include 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.

(Examples 1-10, Comparative Examples 1-7)
1. Composition Preparation In Examples 1 to 10, water-glycol hydraulic fluids were prepared by mixing the components shown in Table 1 in the blending amounts shown in Table 1.
Moreover, the comparative examples 1-7 mixed the component shown by Table 2 with the compounding quantity shown by Table 2, and prepared the water- glycol type hydraulic fluid.
In addition, each water-glycol type | system | group hydraulic fluid of Table 1 and Table 2 contains what is shown below as a thickener, glycols, a lubrication agent, and an alkaline agent. Each composition was adjusted to have a pH of 10.3 and a 40 ° C. kinematic viscosity of 49.0 mm ² / sec depending on the blending amount.

Thickener: A polyoxyethylene / oxypropylene glycol random copolymer having a molar ratio of EO / PO of 75/25. Weight average molecular weight 29,000.
Glycols: Dipropylene glycol
Propylene glycol lubricant: Palm fatty acid Alkaline oleate: Potassium hydroxide (KOH)

2. Evaluation Method For each of the water-glycol based hydraulic fluids described in Tables 1 and 2, the following oxidation stability test was conducted for 24 hours and evaluated by pH measurement. In addition, pH measurement was performed about following (1)-(3), and the result was described in each table | surface. The higher the numerical values of “pH after mixing of deteriorated hydraulic fluid” and “pH after test”, the better the stability of the water-glycol hydraulic fluid.
(1) pH immediately after preparation of water-glycol hydraulic fluid
(2) pH of “deteriorated hydraulic fluid mixture” after mixing 30% by mass of the following “degraded hydraulic fluid” separately adjusted
(3) pH after the oxidation stability test for the “degraded hydraulic fluid mixture” in (2) above

<Oxidation stability test>
An oxidation stability test was carried out under the following conditions using a rotary cylinder type oxidation stability tester defined in item 6 of "JIS K2514 (Lubricating oil oxidation stability test method)".
Test solution volume: 80g
Catalyst; None Test temperature; 120 ° C
Enclosed oxygen pressure; 620
kPa (@ 25 ℃)

<Preparation of “degraded hydraulic fluid”>
A product obtained by degrading Cosmofluid GS46, which is a commercially available water glycol-based hydraulic fluid, using the rotary cylinder type oxidation stability tester until pH 8.0 was used as a “degraded hydraulic fluid”.

The numbers after the components in the table are shown below.
* 1 N, N-dimethylpiperazine: a compound in which R ¹ and R ² are methyl groups in general formula (1) * 2 N-methylpiperazine: a compound in which R ¹ is hydrogen and R ² is methyl groups in general formula (1) * 3 Piperazine: A compound in which R ¹ and R ² are hydrogen in general formula (1) * 4 N-methylpiperidine: A compound in which R ³ is a methyl group in general formula (2) * 5 N-ethylmorpholine: General formula ( 3) R ⁴ is an ethyl group compound

Of the above examples, Example 10 was subjected to the storage stability test described below. As a result, the deteriorated hydraulic fluid mixture had no turbidity and was excellent in storage stability.
<Storage stability test>
The “deteriorated working fluid mixture” after the oxidation stability test was allowed to stand at 0 ° C. for 1 week, and the appearance was visually confirmed.

* 5 N-ethylmorpholine: Compound with general formula (3) and R ⁴ is ethyl group * 6 Morpholine: Compound with general formula (3) and R ⁴ is hydrogen atom

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

Claims (4)

A hydrous working fluid comprising 0.01 to 1% by mass of one or more selected from the compounds represented by the general formulas (1) and (2).

(In the formula, R ¹ and R ² are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and at least one of R ¹ and R ² is an alkyl group having 1 to 3 carbon atoms.)

(In the formula, R ³ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.) The water-containing hydraulic fluid according to claim 1, comprising 0.01 to 1% by mass of the compound represented by the general formula (3).

(In the formula, R ⁴ is an alkyl group having 1 to 3 carbon atoms.)   The water-containing working fluid according to claim 1 or 2, comprising 0.01 to 1% by mass of one or more compounds selected from benzotriazole and tolyltriazole. The water-containing hydraulic fluid according to any one of claims 1 to 3, wherein the water-containing hydraulic fluid is a water-glycol hydraulic fluid.