JPH0776695A - Water/glycol-based hydraulic liquid - Google Patents

Abstract

PURPOSE:To provide a water/glycol-based hydraulic liquid containing a specific water-soluble polyurethane resin, having a viscosity adjustable to a proper level by the addition of a small amount of the resin, exhibiting excellent lubricity, metal-abrasion resistance and durability and useful for a vane pump of a hydraulic apparatus, etc. CONSTITUTION:This water/glycol-based hydraulic liquid contains water, glycol and preferably 5-20wt.% of a water-soluble polyurethane resin (having an NHCOO concentration of preferably 0.1-5wt.%) having a weight-average molecular weight of 5,000-300,000 and an oxyethylene unit content of >=260wt.% and derived from (A) a water-soluble polyoxyalkylene polyol such as an ethylene oxide homopolymer and/or a random or block copolymer of ethylene oxide and propylene oxide and (B) an organic polyisocyanate such as 4,4'- diphenylmethane diisocyanate.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a water-glycol type hydraulic fluid. More specifically, the present invention relates to a water-glycol type hydraulic fluid having excellent durability, lubricity and metal abrasion resistance.

[0002]

2. Description of the Related Art Conventionally, mineral oil type hydraulic fluids have been used as various hydraulic fluids for hydraulic machines and the like. -Glycol type hydraulic fluids have come into use. However, the water-glycol type hydraulic fluid does not have sufficient metal abrasion resistance, and therefore not only wears the friction portion of the hydraulic equipment, but also the metal powder generated by the abrasion is mixed into the hydraulic fluid and the hydraulic fluid itself. It has a drawback that various problems occur due to accelerated deterioration of turbidity. This is due to the lack of lubricity of the water-glycol type working fluid, and it is known that the lubricity is improved by making the working fluid have an appropriate viscosity. It has been proposed to improve the lubricity of a water-glycol type working fluid by adding a polyoxyalkylene polyol derivative such as the alkylene oxide adduct of (1) or the alkylene oxide adduct of polyhydric alcohol (for example, JP-B-5).
8-21958, Japanese Patent Publication No. 60-53079). However, in any case, a large amount of viscosity modifier must be added in order to provide sufficient lubricity, and it is not always possible to provide a satisfactory working fluid from the viewpoint of contamination at the time of leakage, economical efficiency, etc. .

[0003]

DISCLOSURE OF THE INVENTION The object of the present invention is to provide a water having good metal abrasion resistance, which can adjust the viscosity to a proper level with a smaller amount than conventional viscosity modifiers and can improve lubricity. It is to provide a glycol type hydraulic fluid.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that by using a specific water-soluble polyurethane resin as a viscosity modifier, a smaller amount than conventional viscosity modifiers can be used. It was found that a water-glycol type hydraulic fluid having excellent lubricity and good metal abrasion resistance was obtained, and the present invention was accomplished. That is, according to the present invention, in a water-glycol type working fluid containing water and glycol, the weight average molecular weight derived from the water-soluble polyoxyalkylene polyol (A) and the organic polyisocyanate (B) is 5,000 to 300, Water and a water-soluble polyurethane resin having a content of oxyethylene units of at least 60% by weight.
It is a glycol type hydraulic fluid.

Examples of the water-soluble polyoxyalkylene compound (A) of the present invention include ethylene oxide (E
O) homopolymer, EO / propylene oxide (PO)
Copolymer, compound (a) having a hydroxyl group, EO
Alone or EO and other alkylene oxides [PO,
1,2-butylene oxide, tetrahydrofuran, α
-Olefin oxide and the like, alkylene oxide substitution products (epichlorohydrin, styrene oxide and the like)] are added, and a mixture of two or more of these compounds can be mentioned. Examples of (a) include polyhydric alcohols (butylene glycol, hexylene glycol, polypropylene glycol, polyoxytetramethylene glycol, polycaprolactam, dimethylolpropionic acid (salt), glycerin, trimethylolpropane, trimethylolethane, penta Erythritol, sorbitol, sucrose, etc.); polyhydric phenols (hydroquinone,
Catechol, etc.); bisphenols (bisphenol A, bisphenol S, tetramethylbisphenol A, tetramethylbisphenol S, etc.) and water. Of these, preferred are ethylene glycol, propylene glycol and water. The addition mode when other alkylene oxide is used together with EO may be random addition or block addition. Among those exemplified above as (A), particularly preferable ones are polyethylene glycol and EO / PO random copolymers. The average oxyethylene unit content in (A) is usually 60% by weight or more, preferably 70% by weight or more.

The number average molecular weight of (A) is usually 1,000.
To 30,000, preferably 2,000 to 25,000
Is. When the number average molecular weight of (A) is less than 1,000,
The polyurethane resin becomes poorly soluble in water, and when it exceeds 30,000, the reactivity with the polyisocyanate (B) becomes poor and it becomes difficult to obtain the water-soluble polyurethane resin (C) having the desired performance.

Further, the above-mentioned (A) is used as the polyol component.
At the same time, if necessary, another compound having a hydroxyl group can be used in combination within a range that does not impair the water solubility of the water-soluble polyurethane resin (C). Other compounds having a hydroxyl group include the compounds having a hydroxyl group (excluding water) exemplified as the above (a). The amount of the compound used is
It is usually 10% by weight or less with respect to (A).

In the present invention, examples of the polyisocyanate (B) include 4,4'-diphenylmethane diisocyanate (MDI), 2,4- or 2,6-tolylene diisocyanate (TDI) and hexamethylene diisocyanate (HDI). , Isophorone diisocyanate (IPDI), ethylene diisocyanate, 1,5-naphthylene diisocyanate, 4,4'-dibenzyl diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, xylylene diisocyanate and other organic diisocyanates A reaction product of tolylene diisocyanate and trimethylolpropane; a polyphenylmethane polyisocyanate obtained by phosgenating a polyamine obtained by reacting aniline with formaldehyde in the presence of hydrochloric acid; Extent in the resulting crude polyisocyanates; and the like, and mixtures of two or more thereof. Of these, preferred are organic diisocyanates and crude diphenylmethane diisocyanate, and particularly preferred are MDI and TD.
I, IPDI and HDI.

The concentration of urethane group (-NHCOO-) in the water-soluble polyurethane resin (C) is usually 0.1 to 5% by weight,
It is preferably 0.1 to 3% by weight. If the urethane group concentration in (C) is less than 0.1% by weight, the metal abrasion resistance is insufficient, and if it exceeds 5% by weight, the water solubility of (C) deteriorates. The weight average molecular weight of (C) is usually 5,000 to 30.
50,000, preferably 10,000 to 100,000
Is. When the weight average molecular weight is less than 5,000, metal abrasion resistance is insufficient, and when it exceeds 300,000, shear stability is deteriorated. The molecular weight distribution (represented by weight average molecular weight / number average molecular weight) of the (C) is usually 1.2 to 6.
0, preferably 1.3 to 4.0. The content of oxyethylene units in (C) is usually 60% by weight or more, preferably 70% by weight or more. When the content of the oxyethylene unit is less than 60% by weight, the water solubility becomes insufficient and the homogeneity of the working fluid may be impaired.

The method for producing the water-soluble polyurethane resin (C) is not particularly limited, and it can be obtained by reacting (A) with (B) by a usual method for producing a urethane polymer.
The reaction temperature is usually 30 to 200 ° C., preferably 50 to 18
It is 0 ° C. The reaction time is usually 0.1 to 30 hours, preferably 0.1 to 8 hours. This reaction is usually carried out in a solventless system, but if necessary, it may be carried out in an organic solvent inert to isocyanate. Examples of the organic solvent include acetone, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, toluene, dioxane and the like. When these solvents are used, the solvent is usually distilled off after the reaction to obtain the water-soluble polyurethane resin (C).

The water-glycol type working fluid of the present invention can be prepared by using a water-soluble polyurethane resin (C) in place of all or a part of the viscosity modifiers that have been conventionally used. The content of (C) in the hydraulic fluid of the present invention is usually 3 to 25% by weight, preferably 5 to 20% by weight. If the content of (C) is less than 3% by weight, the lubricity and metal abrasion resistance are poor, and if it exceeds 25% by weight, the viscosity of the working fluid increases and the load on the pump becomes too large, which is not preferable.

An example of the formulation of the water-glycol type working fluid of the present invention is as follows. Water 35 to 40% by weight, water-soluble polyurethane resin (C) 5 to 20% by weight, glycol 25 to 50% by weight, oiliness improver. 0 to 10% by weight, rust preventive 0 to 5% by weight, pH adjuster, defoaming agent, antioxidant and sequestering agent become 0 to 2% by weight, respectively. Also,
Other known viscosity modifiers (for example, polyoxyalkylene polyol) may be used in combination with (C), if necessary. The mixing ratio in that case is not particularly limited, but usually,
It is 50% by weight or less based on (C).

As the glycol, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, hexylene glycol, dihexylene glycol, trihexylene glycol and a mixture of two or more thereof are used. To be

Examples of the oiliness improver include aliphatic or aromatic carboxylic acids (capric acid, oleic acid, isostearic acid, benzoic acid, dimethylbenzoic acid, etc.) and alkali metal salts thereof.

As the rust preventive, organic amines (monoethanolamine, triethanolamine, N-dimethylaminoethanol, ethylenediamine, diethylenetriamine, cyclohexylamine, morpholine, 1,4-bis-2-aminoethylpiperazine, 2-heptadecyl are used. -1
-(2-hydroxyethyl) imidazoline and the like); organic amine derivatives (the alkylene oxide adducts of the above amines and the like); the aforementioned carboxylic acid alkali metal salts; cyclohexylamine nitrite and the like. Examples of the pH adjusting agent include the above-mentioned organic amines and hydroxides of alkali metals, and in some cases, they may also serve as an oiliness improver or a rust preventive.

A silicon-based defoaming agent is usually used as the defoaming agent. Benzotriazole, as an antioxidant,
Examples thereof include mercaptobenzimidazole and mercaptobenzothiazole. Examples of the anti-coloring agent include basic dyes and acid dyes. Examples of the sequestering agent include, for example, ethylenediamine tetraacetic acid, diethylenetriamine pentaacetic acid or derivatives thereof (especially metal salts); oxycarboxylic acids such as gluconic acid and tartaric acid or derivatives thereof (especially metal salts). Examples include one kind or a mixture of two or more kinds selected.

[0017]

The present invention will be further described with reference to the following examples, but the present invention is not limited thereto. In the following, "part" means part by weight and "%" means% by weight.

Production Example 1 Polyethylene glycol (number average molecular weight 6,000) 9
0 part, EO / PO copolymer [polypropylene glycol (number average molecular weight 1,700) with EO added; number average molecular weight 8,500, EO = 80% by weight] 50 parts and MDI 7 parts (urethane group concentration 0 .69%) to 160 ° C
At room temperature for 2.5 hours to obtain the water-soluble polyurethane resin [1] of the present invention. The weight average molecular weight of the [1] by gel permeation gas chromatography (GPC) was 63,000, and the molecular weight distribution (weight average molecular weight / number average molecular weight) was 1.5.

Production Example 2 Polyalkylene polyol [hexylene glycol to E
Random addition of O and PO; number average molecular weight 15,
000, EO = 75% by weight] 200 parts and TDI 1.
4 parts (urethane group concentration 0.34%) were reacted at 150 ° C. for 6 hours to obtain the water-soluble polyurethane resin [2] of the present invention. The weight average molecular weight of the [2] by GPC is 40,0.
00, the molecular weight distribution was 1.4.

Production Example 3 EO / PO copolymer [ethylene glycol with EO and PO
Randomly added; number average molecular weight 4,000, E
O = 80% by weight] 200 parts and HDI 5.9 parts (urethane group concentration 1,42%) are reacted at 170 ° C. for 8 hours,
A water-soluble polyurethane resin [3] of the present invention was obtained. GPC
The weight average molecular weight of [3] was 45,000 and the molecular weight distribution was 1.5.

Production Example 4 Polyalkylene polyol [Glycerin with random addition of EO and PO; number average molecular weight of 30,000, EO
= 65% by weight] 200 parts and IPDI 1.5 parts (urethane group concentration 0.28%) are reacted at 150 ° C. for 8 hours,
A water-soluble polyurethane resin [4] of the present invention was obtained. GPC
The weight average molecular weight of [4] was 58,000, and the molecular weight distribution was 2.4.

Examples 1 to 4 Water-soluble urethane resins [1] to [4] obtained in Production Examples 1 to 4
Was used to prepare the water-glycol type working fluid of the present invention according to the formulation shown in Table 1.

Comparative Examples 1-2 EO / PO random copolymer (EO: PO = 75: 2)
5, a weight average molecular weight of 15,000) was used as a viscosity modifier to prepare a comparative water-glycol type working fluid according to the formulation shown in Table 1.

[0024]

[Table 1]

Performance Test Examples For the water-glycol type hydraulic fluids prepared in Examples 1 to 4 and Comparative Examples 1 and 2, ASTM D 2822-70T.
Table 2 shows the results of the pump test according to the above. The measuring device and conditions are as follows. (A) Hydraulic pump; Vickers V-104-E type vane pump (b) Oil amount; 40 l (c) Relief valve set pressure; 70 kg / cm ² (d) Rotation speed; 1200 rpm (e) Pump inlet temperature; 50 C. (f) Test time: 250 hours Further, evaluation as a working fluid was performed by the total amount of wear of the vane of the pump and the cam ring, the state of sludge adhesion and the appearance of the working fluid after the test.

[0026]

[Table 2] As is clear from Table 2, the water-glycol type working fluid of the present invention has little wear, almost no sludge adhesion on the tip of the vane is observed, and there is no change in the appearance of the test fluid. There is.

[0027]

The water-glycol type hydraulic fluid of the present invention has the following effects. (1) It is possible to greatly improve the shortage of lubricity and metal abrasion resistance, which are the drawbacks of the conventional water-glycol type hydraulic fluid containing polyoxyalkylene polyol. (2) Since the working fluid does not become turbid even when used for a long period of time, it does not impair the general properties required for the water-glycol type working fluid, such as flame resistance, water solubility, viscosity characteristics, degradability, and shear stability. ,
It is possible to extend the replacement period of each component of the pump body, the filter, etc., and prevent malfunction of the equipment due to sludge deposition. (3) Since a small amount of addition produces good hydraulic fluid performance,
Excellent in economy. Since it has the above effects, the water-glycol type hydraulic fluid of the present invention, opening and closing of hot rolling equipment and various heating furnaces of iron mills,
It is extremely useful as a hydraulic fluid for various press machines such as die casting machines, vane pumps and gear pumps of hydraulic devices such as hot coil conveyors, cranes, and forklifts.

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Claims (4)

[Claims] 1. A water-glycol type working fluid containing water and glycol, which has a weight average molecular weight of 5,000 to 300, derived from a water-soluble polyoxyalkylene polyol (A) and an organic polyisocyanate (B). 0
Water-soluble polyurethane resin (C) having a oxyethylene unit content of at least 60% by weight
A water-glycol type hydraulic fluid comprising: 2. The water-glycol type working fluid according to claim 1, wherein (A) is an ethylene oxide homopolymer and / or a random or block copolymer of ethylene oxide and propylene oxide. 3. A urethane group (—NHCOO) in (C).
-) The water-glycol type hydraulic fluid according to claim 1 or 2, which has a concentration of 0.1 to 5% by weight. 4. The water-glycol type hydraulic fluid according to claim 1, wherein the content of (C) is 5 to 20% by weight.