JP2000178576A - Water-soluble hydraulic fluid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-soluble hydraulic fluid which is a composition substantially free of glycol for solving the problem of water treatment and yet retains functions required for a hydraulic fluid to levels comparable to those of conventional water/glycol hydraulic fluids. SOLUTION: This hydraulic fluid satisfies all of the following conditions (a), (b), (c) and (d): (a) it comprises from 20 to 60 wt.% polyether which is prepared using a compound having two or more active hydrogen groups in a molecule as a starting material, which is addition polymerized with an alkylene oxide to achieve an average molecular weight per active hydrogen group of from 1,000 to 5,000, is terminated with hydroxyl groups as all terminals, and is optionally water-compatible at from 0 to 50 deg.C; (b) comprises 40 wt.% or more water; (c) has a total of (a) the polyether and (b) water of 90 wt.% or more; and (d) is substantially free of a water-soluble polyhydric alcohol such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butane diol, pentane diol, hexylene glycol, glycerin, pentaerythritol or sorbitol or a derivative thereof which is a water-soluble compound having a molecular weight of smaller than 2,000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic fluid (synonymous with hydraulic fluid and hydraulic fluid) as a pressure transmission medium in a hydraulic system, and is not particularly limited to use as a flame-retardant hydraulic fluid. It can be used in fields where a water glycol-based hydraulic fluid is used. Hydraulic hydraulic fluids are classified into mineral oil-based, synthetic oil-based, and water-containing hydraulic fluids. Synthetic oil-based and hydrous hydraulic fluids are used to prevent fire accidents.
It is positioned as a flame retardant hydraulic fluid for general mineral oil systems.

[0002]

2. Description of the Related Art Hydraulic hydraulic oil, such as steel equipment, die-casting machines, and welding robots for automobile assembly equipment, has a risk of fire when flammable hydraulic oil is used, and flame-resistant hydraulic oil is used. . The flame-retardant hydraulic fluid includes a phosphate ester type hydraulic fluid and a fatty acid ester type hydraulic fluid as a synthetic system, and a water glycol type hydraulic fluid, a W / O emulsion type hydraulic fluid, and an O / W emulsion type hydraulic fluid as a water-containing type. is there.
Among these flame-retardant hydraulic fluids, the water-glycol-based hydraulic fluid has a well-balanced function as a hydraulic fluid, has excellent flame retardancy, and is relatively inexpensive. Therefore, the field of use has been steadily expanding as the mainstream of flame-retardant hydraulic fluids.

[0003]

The conventional aqueous glycol-based hydraulic fluid contains, as main components, a solubilizing agent and a pour point depressant glycol in an amount of about 35 to 45% by weight, and a polyether as a thickener. About 10 to 20% by weight of a nonionic water-soluble high molecular compound such as a compound is contained, and these two components occupy most of the COD load. These two components are
Since all are nonionic water-soluble substances, they cannot be removed by the coagulation treatment which is a general water treatment method.
In order to reduce OD, it was necessary to combine a water treatment method other than the aggregation treatment.

From the findings so far, biological treatments and oxidation treatments are effective as water treatment methods capable of removing glycols, and adsorption treatments and membrane filtration treatments are examples of water treatment methods capable of removing polyethers. It has been clarified that it is effective, and it was possible to reduce the COD of the water glycol-based hydraulic fluid drainage by a combination of these treatment methods. However, a combination of a plurality of processing methods is not practiced because it has various disadvantages such as processing cost, processing equipment cost, and occupied area of the processing equipment. That is, C accompanying the mixing of the water glycol-based hydraulic fluid into the wastewater
In order to solve the problem of increase in OD, it was necessary to change the composition of the working fluid to allow water treatment by a general treatment method already used.

[0005] From the above, a water-soluble hydraulic fluid containing no glycol component is also considered. However, when glycol is removed from a water-glycol-based hydraulic fluid, an important function as a hydraulic fluid is to maintain a proper viscosity and to use hydraulic equipment. It is difficult to maintain the suitability (mainly lubricity). An object of the present invention is to solve the problems related to water treatment by using a composition that is substantially free of glycol, and is capable of maintaining functions required as a hydraulic fluid equivalent to those of a conventional water glycol-based hydraulic fluid. To provide a hydraulic fluid.

[0006]

Means for Solving the Problems The present invention provides the following (a):
The present invention relates to a water-soluble hydraulic fluid that satisfies all of the conditions (b), (c), and (d). (A) Starting from a compound having two or more active hydrogen groups in one molecule, the average molecular weight per active hydrogen group is 10
20 to 60% by weight of a polyether which is an addition-polymerized alkylene oxide having a hydroxyl group of from 00 to 5000, and is optionally compatible with water in the range of 0 ° C to 50 ° C. (B) 40% by weight or more of water;
(C) The sum of the polyether of (a) and water of (b) is 9
0% by weight or more, (d) water-soluble polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butanediol, pentanediol, hexylene glycol, glycerin, pentaerythritol and sorbitol, and derivatives thereof It does not substantially contain a water-soluble compound having a molecular weight of less than 2000.

According to the present invention, as a result of earnestly studying the relationship between the constituents of the working fluid and the water treatment properties and the required functions of the working fluid, the present invention includes nonionic water-soluble low molecular weight compounds represented by glycol. Instead, using a water-soluble polyether having a specific average molecular weight and a functional group number and water as base components, a water-soluble working fluid having a sufficient function as a working fluid was completed. Further, in the present invention, by optimizing the hydrophilic-hydrophobic balance of the polyether as a base material component, it is possible to maintain the same lubricity as a conventional water glycol-based hydraulic fluid even in a system containing no glycol.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As a starting material in (a) of the present invention, compounds having two or more active hydrogens in one molecule include, for example, ethylene glycol, propylene glycol, glycerin, pentaerythritol, sorbitol and the like. Examples include polyhydric alcohols, polyamines such as ethylenediamine and hexamethylenediamine, polycarboxylic acids such as maleic acid, phthalic acid, and succinic acid, and polyamides. Examples of the alkylene oxide include ethylene oxide, propylene oxide, and butylene oxide.

The polyether of the present invention can be easily obtained by subjecting an active hydrogen group of the above-mentioned starting material to addition polymerization of an alkylene oxide according to a conventional method.

The average molecular weight per active hydrogen group of the above polyether is preferably in the range of 1,000 to 5,000.
When the molecular weight exceeds 5,000, the influence of the terminal hydroxyl group having strong hydrophilicity becomes relatively small, so that the hydrophobicity becomes too strong in the hydrophilic-hydrophobic balance. On the other hand, if the value is less than 1000, the thickening effect becomes small, and it becomes impossible to maintain an appropriate viscosity in a system having a water content of 40% or more. Preferably, the range of 2000 to 5000 is desirable.
In addition, since the polyether dislikes separation and precipitation of solid components when using the working fluid, it is necessary that the polyether be arbitrarily compatible with water in the operating temperature range of 0 ° C to 50 ° C.

In the present invention, the polyether needs to be contained in an amount of 20 to 60% by weight in order to impart necessary viscosity to the working fluid and to exert the effect of the lubricant additive. If the content is less than 20% by weight,
It is difficult to impart the required viscosity to the working fluid, and if the content is more than 60% by weight, the content of water as another component is less than 40% by weight, and the flame retardancy is reduced. Would.

In the present invention, water is at least 40% by weight, preferably 40 to 75% by weight. This is for imparting sufficient flame retardancy as a flame-retardant hydraulic fluid. If the water content is less than 40% by weight, the flame retardancy decreases. Further, from the viewpoint of securing more excellent flame retardancy and cost, the content is preferably 50% by weight or more, more preferably 60% by weight or more.

In the present invention, the condition that the total of the polyether of (a) and the water of (b) is 90% by weight or more is to limit the content of the additive component to the entirety to less than 10% by weight. As additives for the water-soluble hydraulic fluid, lubricating additives, rust inhibitors, corrosion inhibitors, defoamers and the like are used. Among these, COD is used in general water treatment methods.
Components that are difficult to reduce loading may be used. In other words, considering actual drainage regulations, COD
It is necessary that the water content is not less than 90% by weight of water and polyether which can be removed by activated carbon adsorption treatment.
Particularly, 90 to 98% by weight is preferable.

The condition (d) is a condition for ensuring the water-treating property of the working fluid of the present invention. The glycols and glycol derivatives are difficult to reduce in general water treatment.
It is necessary that these components are not substantially contained in order to give a D load. Here, the term "substantially not included" means that
A small amount that does not impair the object of the present invention is meant, but is most preferably not contained at all.

It is to be noted that any additive can be used as long as the object of the present invention is not impaired. For example, extreme pressure agents, corrosion inhibitors, lubricating additives, rust inhibitors, pH adjusters, sequestering agents, defoamers, coloring agents and the like can be mentioned. Examples of extreme pressure agents include sulfur compounds and phosphorus compounds. Examples of corrosion inhibitors include benzotriazole and mercaptobenzothiazole. Examples of lubricating additives include, but are not limited to, those having 6 carbon atoms.
As described above, preferred are 8-36 monocarboxylic acids and dicarboxylic acids. Specifically, caprylic acid, capric acid, lauric acid, oleic acid, myristic acid, palmitic acid, stearic acid, other aromatic fatty acids, dimer acid and the like are preferable.

As the basic compound used as a pH adjuster for the purpose of rust prevention, specifically, KOH, Na
Inorganic alkalis such as OH, alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, methyldiethanolamine, ethyldiethanolamine, dimethylethanolamine, diethylethanolamine and triisopropanolamine, monomethylamine, dimethylamine, trimethylamine, cyclohexylamine, etc. And polyamines such as ethylenediamine and diethylenetriamine, and morpholines. As sequestering agents, aminocarboxylic acids such as ethylenediaminetetraacetate, etc., as defoaming agents, silicon compounds, polyether type, special nonionic type, etc., as emulsions, as coloring agents, organic dyes And the like are specific examples.

The water-soluble hydraulic fluid of the present invention can be obtained by uniformly dissolving the above components. The procedure for dissolution is not particularly limited because the working liquid is not an irreversible system such as an emulsified system but a reversible solution.

[0018]

EXAMPLES The difference between the product of the present invention and the conventional product will be specifically described below with reference to Examples and Comparative Examples of formulations shown in Table 1, but the present invention is not limited to these. The polymers described in Table 1 have the structures described below. Polymer 1: polyalkylene glycol having a molecular weight of about 2,000 per functional group obtained by randomly adding ethylene oxide and propylene oxide to a trifunctional polyol. Polymer 2: randomly adding ethylene oxide and propylene oxide to a trifunctional polyol. 3: a polyalkylene glycol polymer having a molecular weight of about 3,000 per functional group obtained by random addition of ethylene oxide and propylene oxide to a trifunctional polyol; a polyalkylene glycol polymer having a molecular weight of about 4,500 per functional group A polyalkylene glycol having a molecular weight of about 5,200 per functional group obtained by randomly adding ethylene oxide and propylene oxide to a 4: 3 functional polyol. The Kishido obtained by adding a random, polyalkylene glycol Note any polyether about 8,300 molecules per functional group amount, optionally compatible with water in the range of 0 ° C. to 50 ° C..

[0019]

[Table 1]

The test evaluation methods and evaluation conditions are as follows. Table 2 shows the results. (1) Pump abrasion resistance test Hydraulic circuit: Conforms to ASTM D-2882 Pump used: F11-SQP2-12 vane pump (manufactured by Tokimec) Liquid temperature: 40 to 50 ° C Discharge pressure: 17.5 MPa Motor rotation speed: 1200 rpm Evaluation method : After running for a predetermined time, the amount of wear of the cam ring as a sliding part was measured.

(2) Activated carbon adsorption treatment test Treated raw water: a sample solution diluted 100-fold with ion-exchanged water Activated carbon: Powdered activated carbon (Taihei Kagaku Sangyo Co., Ltd., Umebee F charcoal) Treatment method: 10,000 ppm of activated carbon in treated raw water After input,
Filtration after stirring at room temperature for 1 hour Evaluation: CODCr before and after the treatment was measured, and the COD reduction rate after the treatment was calculated.

[0022]

[Table 2]

As can be seen from the table, in the examples, the wear amount was as small as 100 mg or less in the pump wear resistance test.
In addition, the wear tends to stop with time. In addition, in all the activated carbon adsorption treatments, the COD reduction rate exceeded 90%, and the water treatment property was excellent.

[0024]

EFFECT OF THE INVENTION The water-soluble hydraulic fluid of the present invention is superior to conventional water-glycol-based flame-retardant hydraulic fluids in water treatment properties and flame-retardant properties. Has equivalent lubricity.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Akihiko Konami 10-33 Ashiharacho, Nishinomiya-shi, Hyogo Matsumura Petroleum Institute Co., Ltd. F-term (reference) 4H104 AA01Z BB42A CB14A EA17Z PA05 QA05

Claims (1)

[Claims] 1. A water-soluble hydraulic fluid that satisfies all of the following conditions (a), (b), (c) and (d). (A) Starting from a compound having two or more active hydrogen groups in one molecule, the average molecular weight per active hydrogen group is 10
20 to 60% by weight of a polyether which is an addition-polymerized alkylene oxide having a hydroxyl group of from 00 to 5000, and is optionally compatible with water in the range of 0 ° C to 50 ° C. (B) 40% by weight or more of water;
(C) The sum of the polyether of (a) and water of (b) is 9
0% by weight or more, (d) water-soluble polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butanediol, pentanediol, hexylene glycol, glycerin, pentaerythritol and sorbitol, and derivatives thereof It does not substantially contain a water-soluble compound having a molecular weight of less than 2000.