JP2012224795A - Aqueous hydraulic fluid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problems that in a water-glycol hydraulic fluid essentially composed of glycol such as ethylene glycol and propylene glycol and used for hydraulic equipment, even in the case when a rust preventive is added thereto, sometimes, corrosion of partial metal can not be perfectly suppressed, and sludge is produced, thus a filter is clogged, or, sometimes, a sealing material is swelled to deteriorate hardness and strength.SOLUTION: By using glycerin and/or polyglycerol in an aqueous hydraulic fluid, the corrosion of a metallic member can be dominantly inhibited, and further, an influence on a sealing material can be reduced compared with the case of a hydraulic fluid only using glycerin.

Description

  The present invention relates to an aqueous hydraulic fluid used in the steel industry, the automobile industry, the chemical industry, the food and beverage industry, and the pharmaceutical industry.

  Conventionally, hydraulic fluids of various compositions have been used as power transmission media in hydraulic equipment. In particular, hydraulic equipment is often used in places where there is a risk of fire, such as rolling mills and die casting machines, and flame retardant hydraulic fluid is used as a disaster prevention measure. Examples of the flame retardant hydraulic fluid include non-hydrous phosphates and fatty acid esters, hydrous water-glycol hydraulic fluids, and O / W or W / O emulsions, and are particularly excellent in flame retardancy. Therefore, many water-glycol hydraulic fluids are used.

  Currently, commercially available water-glycol hydraulic fluids have the following basic composition.

  As the solvent of the composition component, for example, glycol such as ethylene glycol or propylene glycol is used, and the hydraulic fluid has fluidity at low temperature and also has a role of increasing the compatibility of various additives. As the thickener, polyalkylene glycol having an appropriate molecular weight is used. By adjusting the addition amount, a working fluid suitable for various ISO viscosity grades can be obtained. Water is indispensable for maintaining flame retardancy. Thus, the water-glycol based hydraulic fluid is based on a ternary mixed system of glycol-polyalkylene glycol-water.

  Furthermore, as shown in Table 1, an oily agent, an alkali agent, a rust preventive agent, an antifoaming agent, a colorant and the like are added to improve performance as a working fluid. For example, as the oil agent, unsaturated fatty acids such as oleic acid, saturated fatty acids such as lauric acid and stearic acid, carboxylic acids such as aromatic fatty acids and dimer acids are used to improve lubricity. As the rust preventive agent, an organic amine, an organic amine derivative, an alkali metal carboxylate, or the like is used to suppress metal corrosion. In practice, the aforementioned carboxylic acid and organic amine salt or carboxylic acid alkali metal salt may be used as both an oily agent and a rust inhibitor. Further, metal hydroxides such as sodium hydroxide and potassium hydroxide are used as the alkaline agent, and the pH is set in a pH range where iron is passivated to suppress corrosion.

  However, the water-glycol based hydraulic fluid is different in composition from the hydraulic fluid mainly composed of mineral oil, and various physical properties differ accordingly. Therefore, in the hydraulic system, it is necessary to pay attention to the compatibility with various metal members and sealing materials that may come into contact with the hydraulic fluid.

  Since the water-glycol based hydraulic fluid contains water, there is a concern about the influence on the metal, and therefore, corrosion inhibition is achieved by adding a rust inhibitor. However, metal corrosion cannot be completely suppressed, sludge is generated, and filter clogging may occur. In particular, for aluminum, cadmium, and magnesium, water-glycol hydraulic fluids are corrosive, and therefore cannot be used as materials for valves, pipes, and filters (Non-Patent Document 1, (See 2nd grade).

  For the sealing material, the working fluid may swell rubber, which is a material thereof, so that properties such as hardness and strength necessary for the sealing material cannot be maintained. In particular, the water-glycol based hydraulic fluid swells fluorine, silicone, and acrylic rubber, so that it is inappropriate to use them as a sealing material (see Non-Patent Document 3).

“Checkpoints for water-glycol based hydraulic fluid”, Lubricating Communication Co., Ltd. Homepage Juntsuunette 21, <http: // www. juntsu. co. jp / qa / qa0516. html> "Working oil", Fujikoshi Corporation technical data, <http: // www. nachi-fujikoshi. co. jp / web / hydric / b_catalog2011 / n-01_fluid. pdf> Japanese Industrial Standard JIS B 2410

  The present invention has been made in view of the above-described state of the art, and does not impair the excellent flame retardancy of the water-glycol-based hydraulic fluid and does not impair various required performances, and the metal member and the sealing material. Provided is an aqueous working fluid that is a homogeneous solution that can improve compatibility.

  As a result of intensive studies, the present inventors have used a glycerin and / or polyglycerin as a water-based working fluid in order to solve the above-described problems. It was found that the corrosion of the rubber and the swelling of the rubber can be suppressed, and the compatibility with the metal member and the sealing material can be improved.

  Corrosion of the metal generated in a general water-glycol based hydraulic fluid is reduced, and generation of sludge due to corrosion can be suppressed. Moreover, the swelling of rubber can be suppressed, and the influence on the hardness and strength of the sealing material can be reduced.

  The glycerin and / or polyglycerin in the present invention is used to make an aqueous working fluid excellent in compatibility with a metal member and a sealing material as compared with a conventional water-glycol working fluid. It replaces part or all. That is, like glycol, glycerin and / or polyglycerin has fluidity at low temperatures and has a function of increasing the compatibility of various additives, and these one or two kinds can be combined in an arbitrary ratio. Can be used. Here, the polyglycerin is a polymer such as a polycondensate of glycerin or glycidol, and those having any degree of polymerization can be used. In the present invention, polyglycerol having an average degree of polymerization of 2 to 20 is preferable.

  In addition, glycerin and / or polyglycerin can be used in combination with glycol at an arbitrary ratio. In the present invention, when glycerin and / or polyglycerin and glycol are used in combination, the blending amount of glycol is less than 4 by weight with respect to the blending amount of glycerin and / or polyglycerin. Preferably there is.

  The blending ratio of glycerin and / or polyglycerin in the present invention is preferably 10 to 50% by weight. When the blending ratio of glycerin and / or polyglycerin is less than 10% by weight, the influence on the metal member and the sealing material is reduced as compared with the water-glycol hydraulic fluid, but the metallic component is used as the aqueous hydraulic fluid. In addition, the influence on the sealing material cannot be sufficiently reduced. Also, if it is 50% by weight or more, the physical properties such as flame retardancy, viscosity, lubricity, etc. necessary for aqueous hydraulic fluids are maintained by reducing the amount of water, thickeners and additives which are other components. Can not do it.

  In addition, by using glycerin and / or polyglycerin in a predetermined ratio in the aqueous working fluid, the compatibility with the metal member and the sealing material is excellent compared to the water-glycol working fluid. However, it is more preferable to use glycerin from the viewpoint of cost effectiveness.

  In the present invention, it is preferable to use other additives in order to obtain physical properties such as viscosity and lubricity necessary for the aqueous working fluid. Examples of other additives include a thickener, an oily agent, a rust preventive agent, an alkali agent, an antifoaming agent, and a colorant.

  As the thickener to be added, polyalkylene glycol obtained by addition polymerization of alkylene oxide to monovalent or polyhydric alcohol is mainly used. As monohydric alcohol, methanol or butanol is used, and as polyhydric alcohol is ethylene glycol. , Propylene glycol, glycerin, neopentyl glycol, trimethylolpropane, pentaerythritol and the like, and ethylene oxide, propylene oxide, butylene oxide and the like are used as the alkylene oxide. Alternatively, alkyl ether derivatives of these polyalkylene glycols are also used. These can be used alone or in combination of two or more suitable thickeners depending on the desired viscosity of the aqueous working fluid.

  Examples of the oily agent to be added include fatty acids such as oleic acid, lauric acid and stearic acid, and dibasic acids such as succinic acid and dimer acid. Moreover, it can use also as derivatives, such as those metal salts and ester, and these can be used individually or in combination of 2 or more types.

  Examples of the rust inhibitor to be added include amine compounds such as triethanolamine, triazole compounds such as benzotriazole, nitrite compounds such as dicyclohexylammonium nitrite, carbamate compounds such as cyclohexyl carbamate, and the like. Alternatively, two or more types can be selected and used. Further, fatty acids, dibasic acids, derivatives thereof such as metal salts and esters, which are added as oil agents, can be added as rust inhibitors.

  Moreover, in order to adjust the pH of the aqueous working fluid composition to be alkaline, a metal hydroxide such as sodium hydroxide or potassium hydroxide can be added as an alkaline agent.

  In addition, a defoaming agent is added to prevent foaming in the aqueous hydraulic fluid, and a colorant is added for early detection in the event of a leak or to distinguish other hydraulic fluids from aqueous hydraulic fluids. You can also

  The aqueous working fluid composition of the present invention can be adjusted by appropriately blending and mixing the respective components in predetermined amounts. The mixing method and addition method in this adjustment are not particularly limited, and can be carried out by various methods. The mixing order and addition order of each component can also be carried out by various mixing orders and addition orders.

  The hydraulic device that can use the aqueous hydraulic fluid composition of the present invention is not particularly limited, and is a machine tool, a die casting machine, a transfer machine, a press machine, a forging machine, a cargo handling machine, a civil engineering construction machine, a plant. Various hydraulic devices used in various machines including control devices, automobiles, ships, aircrafts, rockets, etc., especially high-temperature metal processing devices with fire hazards, devices that generate electric sparks, heating furnaces, It is effective in a hydraulic apparatus used in the vicinity of a heat source such as a continuous casting apparatus, a hot rolling mill, and an aluminum die casting machine. The hydraulic pump used in the hydraulic device is not particularly limited, and can be used for various hydraulic pumps, such as a vane pump, a gear pump, a plunger pump, and a screw pump.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention in detail, this invention is not limited to these Examples.

Example 1
In a 1000 ml four-necked flask, 400 g of glycerin (“Purified Glycerin” manufactured by Sakamoto Pharmaceutical Co., Ltd.), 150 g of polyalkylene glycol (EO, PO copolymer, molecular weight of about 20000), 400 g of water, sodium oleate (Wako Pure Chemical) 20 g of a reagent), 15 g of benzotriazole (a reagent manufactured by Kishida Chemical), and 15 g of potassium hydroxide (a reagent manufactured by Kishida Chemical) were added and stirred at room temperature for 30 minutes to obtain an aqueous working fluid composition.

Examples 2-7
According to the formulation shown in Table 2, stirring was performed in the same manner as in Example 1 to obtain each aqueous working fluid composition.

Comparative Examples 1-3
According to the formulation shown in Table 2, stirring was performed in the same manner as in Example 1 to obtain each aqueous working fluid composition.

  About these water-system hydraulic fluid composition, the property, kinematic viscosity, fluidity | liquidity in -20 degreeC confirmation, the corrosivity test with respect to each metal, and the compatibility test of each sealing material were done by the method described below.

<Properties>
30 g of the composition was placed in a 50 ml transparent glass container and allowed to stand for 30 minutes, and then the presence or absence of insoluble matter was visually confirmed from the side of the transparent glass container.

<Kinematic viscosity>
The kinematic viscosity at 40 ° C. of the composition was measured in a thermostat adjusted to 40 ° C. ± 0.01 ° C. according to JIS K 2283. The proper viscosity varies depending on the hydraulic equipment, but it is preferable to conform to ISO standard viscosity grades VG32, VG46, and VG68. That kinematic viscosity at 40 ° C. of the working fluid, the VG32, 28.8~35.2mm ² / s, the VG46 41.4~51.6mm ² / s, the VG68 61.2~74.8mm ² / s It is preferable to be within the range.

<Confirmation of fluidity at low temperature>
30 g of the composition was put into a 50 ml glass container capable of being sealed, left in a thermostat adjusted to −20 ° C. for 24 hours, and then taken out, and the glass container was tilted 90 ° to check for fluidity. If it is not fluid at low temperatures, it is difficult to use it as an aqueous working fluid in winter and cold regions, so it is desirable to flow at −20 ° C.

Δｍ：質量の変化（ｍｇ／ｃｍ^２）、ｍ_１：試験前の試験片の質量（ｍｇ）、ｍ_２：試験後の試験片の質量（ｍｇ）、Ｓ：試験前の試験片の全表面積（ｃｍ^２）
質量の変化は、銅において±０．１５、はんだにおいて±０．３０、黄銅において±０．１５、鋼において±０．１５、鋳鉄において±０．１５、アルミニウム鋳物において±０．３０の範囲内に収まることが望ましい。 <Metal corrosion test>
In accordance with JIS K 2234, a metal assembly test piece is placed in a glass container provided with a cooler, a thermometer and a vent pipe, various antifreeze compositions are added, dry air is blown at 100 ml / min, and 60 ° C. ± The test was conducted at 2 ° C. for 168 hours. As the metal piece, copper (C1100P), solder (H30A), brass (C2680P), steel (SPCC-SB), cast iron (FC200), aluminum cast iron (AC2A-F), and stainless steel (SUS304) were used. The change in mass was calculated according to equation (1).

Δm: change in mass (mg / cm ² ), m ₁ : mass of test specimen before test (mg), m ₂ : mass of test specimen after test (mg), S: total surface area of test specimen before test (Cm ² )
Mass change is within ± 0.15 for copper, ± 0.30 for solder, ± 0.15 for brass, ± 0.15 for steel, ± 0.15 for cast iron, ± 0.30 for aluminum castings It is desirable to fit in.

ΔＶ_１００：体積変化率（％）、ｍ_１：空気中での試験前のゴム片の質量（ｍｇ）、ｍ_２：水中での試験前の試験片の質量（ｍｇ）、ｍ_３：空気中での試験後のゴム片の質量（ｍｇ）、ｍ_４：水中での試験後の試験片の質量（ｍｇ）
体積変化率について、明確な基準はないが、できるだけ小さいことが好ましい。 <Sealant compatibility test>
In accordance with JIS K 6258, 30 g of the composition in a 50 ml glass container capable of being sealed, rubber pieces of each material are immersed in the glass container, sealed, and adjusted to 60 ° C. ± 1 ° C. for 168 hours. A test was conducted. As rubber pieces, NBR (JIS B 2401: 1 type A), NBR (JIS B 2401: 1 type B), NBR (JIS B 2401: 2 types), SBR (JIS B 2401: 3 types), VQM (JIS) B 2401: 4 species C), FCM (JIS B 2401: 4 species D). The volume change rate was calculated according to equation (2).

ΔV ₁₀₀ : volume change rate (%), m ₁ : mass (mg) of rubber piece before test in air, m ₂ : mass (mg) of test piece before test in water, m ₃ : in air Mass of rubber piece after test in mg (mg), m ₄ : Mass of test piece after test in water (mg)
There is no clear standard for the volume change rate, but it is preferable to be as small as possible.

  The above results are shown in Table 3.

From the above results, by using glycerin and / or polyglycerin as shown in Examples 1 to 7, conventional water-glycol without using the glycerin or polyglycerin shown in Comparative Example 1 and Comparative Example 2 Compared with the system hydraulic fluid, corrosion of the metal and swelling of the rubber can be suppressed, and compatibility with the metal member and the sealing material can be improved.
Moreover, in order to reduce the influence on a metal and a sealing material in the comparative example 3, when the amount of glycol is reduced and the rust preventive agent is increased, an insoluble matter is generated in the composition, and the fluidity at −20 ° C. is also obtained. Unsustainable and undesirable.

  In Example 6, compared with Comparative Example 1 and Comparative Example 2, although corrosion of the metal can be suppressed preferentially, the suppression to some metals is insufficient, and it cannot be said that the aqueous working fluid is sufficient. . In Example 7, although the effect of inhibiting metal corrosion is sufficient, a desired amount of thickener cannot be added due to the large amount of glycerin and / or polyglycerin, and the viscosity is suitable as a working fluid. Is not obtained. That is, by setting the addition amount of glycerin and / or polyglycerin to 10 to 50% by weight described in Examples 1 to 5, the metal corrosiveness, sealing material compatibility, and other physical properties suitable as an aqueous working fluid are obtained. Obtainable.

  Since the aqueous working fluid of the present invention contains glycerin and / or polyglycerin, compared to conventional water-glycol working fluids, corrosion of metals can be suppressed, resulting in generation of sludge, It is possible to suppress the clogging of the filter due to. Moreover, swelling of rubber can be suppressed, and compatibility with a sealing material can be improved. Furthermore, the water-based hydraulic fluid of the present invention does not impair any performance (flame retardancy, viscosity, lubricity, etc.) inherent to conventional water-glycol hydraulic fluids. This eliminates the need for changes in hydraulic equipment specifications and capital investment. Therefore, the aqueous working fluid of the present invention is extremely useful in practice.

Claims (4)

  An aqueous working fluid containing glycerin and / or polyglycerin.   The aqueous working fluid according to claim 1, wherein the concentration of glycerin and / or polyglycerin is 10 to 50% by weight.   The aqueous working fluid according to claim 2, which always contains glycerin.   Furthermore, the aqueous | water-based hydraulic fluid in any one of Claims 1-3 containing at least 1 sort (s) chosen from a thickener, an oiliness agent, a rust preventive agent, an alkali agent, an antifoamer, and a coloring agent.