JP2646309B2 - Water-glycol hydraulic fluid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-glycol-based flame-retardant hydraulic fluid which is a kind of flame-retardant hydraulic oil (hereinafter referred to as "water-glycol-based hydraulic fluid").

[0002]

2. Description of the Related Art Devices utilizing hydraulic pressure have been widely adopted in the industry and have contributed to the improvement of productivity. Among them, devices such as high-temperature metals, electric sparks and heating furnaces coexist with the danger of fire. Uses flame-retardant hydraulic oil as hydraulic oil.

[0003] In the case of using a flammable hydraulic oil, particularly a water-containing hydraulic oil, the problem is that the life of the rolling bearings used in hydraulic pumps and motors is shortened. In other words, when a hydrous hydraulic fluid is used, the life of the rolling bearing is greatly reduced compared to mineral oil or synthetic hydraulic oil, and pump troubles due to bearing damage are likely to occur, impeding the normal operation of the entire hydraulic system. Often do.

[0004] In order to prevent the above-mentioned bearing troubles, the present situation is to improve the hydraulic equipment and install additional facilities. For example, to use at a pressure lower than the rated working pressure that hydraulic equipment originally has, to improve the standard specification bearing part to a specially large one, and to forcibly lubricate bearing parts where lubrication failure is likely to occur Special hydraulic oil circulation circuit is installed.

[0005] Changing the specifications of these devices and investing in equipment are measures that are not particularly necessary if the bearing life of the hydrous hydraulic fluid is improved. It is desired to extend the bearing life of a hydrous hydraulic fluid, especially a water-glycol hydraulic fluid, which is the mainstream of a hydrous hydraulic fluid.

[0006] Water-glycol hydraulic fluids currently on the market have the basic composition shown in Table 1.

[0007]

[Table 1]

Examples of the solvents shown in Table 1 include ethylene glycol, propylene glycol, dipropylene glycol and the like, which have a function of lowering the pour point and also have a role of increasing the compatibility of various additives. included. As the thickener, a polyalkylene glycol having an appropriate molecular weight is used. By adjusting the amount of the thickener to be added, it is possible to obtain a working fluid compatible with various ISO viscosity grades. Water is essential for maintaining flame retardancy.

As described above, typically, a three-component mixed system of glycol (solvent), polyalkylene glycol (thickener) and water is the base oil of the water-glycol hydraulic fluid.

[0010]

However, some of the current water-glycol based hydraulic fluids using these fluids are quite satisfactory in terms of sliding lubrication, but they are not sufficient in terms of rolling lubrication. In other words, there is a trouble that the bearing is damaged in a much shorter time than in the case of the mineral oil-based hydraulic oil due to a reduction in the rolling life of the rolling bearing used in the hydraulic pump and the motor.

[0011] The present invention provides a water-glycol of a uniform solution which can extend the life of a rolling bearing without impairing the excellent flame retardancy of the water-glycol-based hydraulic fluid and without impairing various required performances. It is intended to provide a system hydraulic fluid.

[0012]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above object, and as a result, by adding a specific amount of a specific ether compound, the water-glycol working fluid The present inventors have found that the rolling bearing life can be significantly improved without impairing various performances, and have completed the present invention.

That is, the present invention provides a compound represented by the general formula R ₁ -OR
An ether compound represented by _2- OH (wherein R ₁ represents a saturated or unsaturated hydrocarbon group having 1 to 8 carbon atoms, and R ₂ represents a divalent hydrocarbon group having 2 to 3 carbon atoms) (Hereinafter simply referred to as "ether compound") in an amount of 0.01 to 3.0% by weight.
The gist of the present invention is a water-glycol-based working fluid characterized by containing.

R ₁ in the above general formula is a saturated or unsaturated hydrocarbon group having 1 to 8 carbon atoms, and is a linear or branched alkyl group, a linear or branched allyl group, or an aryl group. It is. For example, a methyl group, an ethyl group, a propyl group,
Isopropyl group, butyl group, isobutyl group, pentyl group, isopentyl group, neopentyl group, hexyl group, isohexyl group, 2-ethylhexyl group, heptyl group, octyl group, propenyl group, 2-methyl-1-propenyl group, 2-methylallyl Group, 2-butenyl group, cyclohexyl group, phenyl group and the like. Preferred are a methyl, propyl, isopropyl, butyl, isobutyl, hexyl, 2-ethylhexyl and phenyl group. If the carbon number of R ₁ exceeds 8, wear tends to occur.

In the above general formula, R ₂ is a group having 2 to 3 carbon atoms.
Particularly preferred are the monovalent hydrocarbon groups, specifically, an ethyl group or a propylene group, wherein at least one of the hydrogen atoms is substituted with a hydroxyl group. R ₂ has 3 carbon atoms
If it exceeds, the specific effect of the present invention will not be exhibited.

The most preferred ether compounds for use as rolling bearing life extenders in the compositions of the present invention are:
It has at least one phenyl group. Representative examples of suitable ether compounds include ethylene glycol monophenyl ether (hereinafter, referred to as “PhG”) and propylene glycol monophenyl ether (hereinafter, “PhFG”).
There is).

The ether bond of the ether compound not only improves the dissolving power of the oil agent added separately, but also functions to make it easier for the ether compound to enter the boundary lubrication surface of the bearing. Further, the hydroxyl group increases the water solubility in water.

Since this component is inherently water-soluble, it is infinitely soluble in a water-glycol hydraulic fluid. However, when added in a large amount, the properties of the water-glycol hydraulic fluid, especially slip lubricity and elastomer properties Inversely, if the amount is too small, the above effect cannot be obtained. Therefore, in the present invention, in the total amount of the composition of the present invention, 0.01 to
The ether compound is added so as to be 3.0% by weight, preferably 0.01 to 1.0% by weight. In the case of hydraulic oil, the operating environment is a closed system, and there is no lubricating oil additive taken out of the system as seen in the case of cutting oil, rolling oil, etc., and the initial concentration is maintained. You. For this reason, excessive addition of the ether compound is disadvantageous in terms of cost.

The base oil in the composition of the present invention is a commonly used water-glycol type hydraulic fluid, which comprises about 25 to 50% by weight of glycols, about 10 to 20% by weight of a thickener, about 3 to 20% by weight.
It consists of 5 to 50% by weight of water. It may contain a lubricant, a liquid phase rust inhibitor, a gas phase rust inhibitor, a metal deactivator, a pH adjuster, a defoamer, a colorant, and other additives.

As the glycols constituting the base oil, glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol and hexylene glycol can be used alone or in combination of two or more. Can be used.

As the thickener constituting the base oil, a polyether thickener such as a polyalkylene glycol or an alkyl ether derivative thereof is usually used. Specific examples thereof include polyoxyalkylene polyols of polyhydric alcohols, for example, Newpol 75H90.
Polyoxyalkylene glycols such as 000 (trade name, manufactured by Sanyo Chemical Co.), polyoxyalkylene triols such as Newpol V-10-C (trade name, manufactured by Sanyo Chemical), and polyoxyalkylenes described in JP-A-54-105653. Polyols: Polyoxyalkylene polyols of polyamides, for example, polyoxyalkylene polyols described in JP-B-51-44275 can be exemplified. These thickeners can be used alone or in combination of two or more.

Examples of the lubricant which may be added to the above base oil include unsaturated fatty acids such as oleic acid, saturated fatty acids such as lauric acid and stearic acid, aromatic fatty acids, and dimer acid.

As the liquid or gas phase rust inhibitor, organic amines (monoethanolamine, triethanolamine,
Ethylenediamine, diethylenetriamine, cyclohexylamine, morpholine, 1,4-bis (2-aminoethyl) piperazine, 2-heptadecyl-1- (2-hydroxyethyl) imidazoline and the like], organic amine derivatives [alkylene oxide adducts of the above amines and the like] And carboxylic acid alkali metal salts and cyclohexylamine nitrite.

Examples of the metal deactivator include alkali metal salts of mercaptobenzothiazole and derivatives of methylbenzotriazole. Examples of the pH adjuster include alkali metal compounds (KOH, NaOH, etc.), alkanolamines, morpholines and the like. Examples of the antifoaming agent include an emulsion of a silicon compound, and examples of the coloring agent include an alcohol-based coloring agent and a metal-based coloring agent.

[0025]

【Example】

Examples 1 to 8 Water-glycol-based hydraulic fluids of the present invention were prepared by adding ether compounds shown in Table 4 to base oils having the compositions shown in Table 3 in the proportions shown in Table 4. A uni-steel rolling life test was performed on these hydraulic fluids under the conditions shown in Table 2 by the method described below, and the results are shown in Table 4. For comparison, a uni-steel rolling life test was carried out using three types of commercially available water-glycol based hydraulic fluids under the same conditions and under the same conditions. The results are also shown in Table 4.

[0026]

[Table 2]

The test method was as follows. The ball bearing is rotated on the washer-shaped test piece under the conditions shown in Table 2. As the operation is continued, small holes of wear due to fatigue, that is, pitching, occur on the track of the test piece. When pitching occurs, vibration occurs in the test section.
The rotation stop vibrometer adjusted so as to stop when it becomes G or more is operated, and the test machine is stopped. Fatigue life time (h
r) was determined as the integrated time up to this point. The exam is
The data was accumulated 5 to 7 times, and the data was accumulated and plotted on Weibull probability paper. 10% life (time when the cumulative failure probability became 10%), 50% life (the cumulative failure probability became 50%) Time).

[0028]

[Table 3]

[0029]

[Table 4]

Incidentally, the flame-retardant hydraulic oil is generally used for a long period of time under severe conditions. Further, the flame-retardant hydraulic oil acts not only as a pressure transmission medium but also as a lubricant for a sliding portion of a hydraulic pump or a hydraulic motor. Further, the flame-retardant hydraulic oil needs to be compatible with various materials (metal material, rubber, etc.) used in the hydraulic system. Therefore, in order to confirm that the water-glycol-based hydraulic fluid of the present invention exerts these effects and also has the above compatibility, a vane pump durability test was performed under the conditions shown in Table 5, Table 6 shows the results.

[0031]

[Table 5]

[0032]

[Table 6]

As is clear from Table 6, the wear amount is saturated after normal initial wear. No discoloration of the cartridge or adhesion of sludge was observed at all, and changes in the general properties (viscosity, pH, preliminary alkalinity, etc.) of the working fluid were very slight, confirming that it exhibited sufficient compatibility. Was done.

Further, with respect to the water-glycol-based hydraulic fluid of the present invention of Examples 1 to 8, at the same time as the above tests, a metal material immersion test (according to JIS K 2234) and a rubber material immersion test (according to JIS K 6301). ) Was carried out, but in these tests, there was no problem, and it was confirmed that the water-glycol-based hydraulic fluid of the present invention had sufficient compatibility as a hydraulic oil.

[0035]

The water-glycol hydraulic fluid of the present invention contains a specific amount of a specific ether compound in its components, so that the lubricating properties are improved and, in particular, the occurrence of pitting in rolling bearings is effectively suppressed. be able to. In addition, the water-glycol hydraulic fluid of the present invention can easily penetrate the sliding lubrication surface and the rolling surface of the bearing, and can greatly extend the life of the rolling bearing due to the specific structure. Further, the water-glycol based hydraulic fluid of the present invention has an effect of not impairing various properties (flame retardancy, low temperature fluidity, metal compatibility, etc.) inherently provided by the water-glycol based hydraulic fluid. ing. As a result, in the various devices using the water-glycol-based hydraulic fluid of the present invention, high pressure can be used, and these devices can be downsized, and the secondary effect is large.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C10N 40:02 40:08

Claims (1)

(57) [Claims] 1. A compound of the general formula R ₁ —O—R ₂ —OH wherein
₁ is a saturated or unsaturated hydrocarbon group having 1 to 8 carbon atoms,
Wherein R ₂ represents a divalent hydrocarbon group having 2 to 3 carbon atoms) in an amount of 0.01 to 3.0% by weight.