JP2011173997A - Lubricating method using water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricating method using water that improves lubricity (extreme pressure properties and low friction) and also has low environmental load when water is used as a lubricant from the aspect of safety and good hygiene. <P>SOLUTION: In the lubricating method, a gel-like lubricant or grease, which is obtained by blending 1-60 mass% of a thickener based on the total composition with mineral oil-based, synthetic oil-based and/or animal and vegetable oil-based lubricating oil and producing a semisolid state, is applied to a sliding part, and subsequently the sliding part is lubricated with water. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lubrication method using water, which is the most preferred liquid, in terms of safety and low environmental load.

  Attempts have been made to use water as a base for lubricants instead of oils, but since the viscosity of water is too low to provide the required lubricity, there has been no realization of a general-purpose tribo system using water lubrication. . In order to obtain a high lubrication effect using water as a base for the lubricant, it is said that it is essential to develop a water lubrication system including an additive having a small impact on the environment from the viewpoint of ecology. However, no practical system has been found, and how to use water as a lubricant has become a problem.

  As an attempt to use water as a lubricant, there has been reported a hydraulic operation system that can withstand practical use to some extent in a low load region. However, in the case of a machine element such as a rolling bearing that receives a high contact surface pressure during operation, even if the bearing material is ceramics, water lubrication may only show a bearing life of about a few percent that of oil lubrication. It has been reported (Non-Patent Document 1). Water lubrication is mainly handled from the sliding material surface (Patent Documents 1 and 2), and almost no correspondence is observed in the lubrication method. In other words, it can be said that the water lubrication technology is still far from practical use.

JP-A-7-293556 JP-A-10-101461

"Research and development on low environmental load tribo system using water-based lubrication" Kagawa Prefectural Science and Technology Foundation, Industry-Academia-Government Joint Research and Development Project Report (2001)

  The present invention provides a lubrication method that improves lubricity, particularly extreme pressure properties, and further improves efficiency by reducing friction when water is used as a lubricant for safety and hygiene purposes. The purpose is to provide.

In developing a lubrication method that solves the above-mentioned problems, the inventors focused on a semi-solid lubricant such as grease, particularly a gel lubricant, and lubricated the sliding material coated with water with water. As a result, the present inventors have found that wear is reduced and friction is reduced, and the present invention has been completed.
The gel lubricant is a semi-solid, with a polar gelling agent forming a three-dimensional matrix (micelle) by hydrogen bonding, and lubricating oil (base oil and additive) is taken into it. In addition, since the gelling agent is difficult to dissolve in water, the micelle is not destroyed, and the sliding part during operation of the equipment / machine is covered with a coating of gelling agent, and the water flows around it, mainly cooling Work for sealing. On the other hand, gel-like lubricants contain a large amount of gelling agent, which is an oily agent itself, and because it is in a semi-solid state, it forms a strong adsorption film while incorporating various additives, and wears. Can be reduced and the friction can be reduced.
From these facts, it was found that a lubrication method using water for the sliding portion after applying a semi-solid lubricant, particularly a gel lubricant, to the sliding portion is an extremely useful water lubrication method. .

That is, the present invention is a lubrication method as follows.
(1) A gel-like lubricant or grease obtained by semi-solidifying a mineral oil, synthetic oil and / or animal and vegetable oil based lubricant with 1 to 60% by mass of a thickener based on the total composition. A lubrication method in which the sliding part is lubricated with water after being applied to the sliding part.

  In particular, (2) The lubricating method according to the above (1), wherein the thickener is an amide compound having a melting point of 50 to 300 ° C.

  Furthermore, (3) The lubrication method according to the above (1) or (2), wherein the liquefying temperature of the semi-solid gel lubricant is higher than the water temperature in the sliding portion during operation.

  (4) The lubricating method according to any one of (1) to (3), wherein the base oil of the gel lubricant is biodegradable.

According to the lubricating method of the present invention, even when water that is inferior in lubricity as compared with an oil agent is used as a liquid lubricant, the gel lubricant or grease applied to the sliding portion is a sliding material such as a metal. In order to form a sufficient film that prevents mutual contact, the lubricity comparable to that of an oil agent, and further, the friction can be reduced to increase the efficiency of the machine. Further, since the liquid is water, an extremely safe working environment is created, and at the same time, the gel-like lubricant or grease is not evaporated to the atmosphere, so that the surrounding environment is prevented from being contaminated.
This lubrication method works as a main lubricant until the coated semi-solid gel lubricant or grease is consumed and there is no coating on the sliding material surface. Useful. Further, since the surface of the sliding material is smoothed by the operation of the equipment / machine until the coating disappears, the effect of wear reduction and low friction is maintained. If the coating is consumed and water lubrication alone is insufficient, the effect can be maintained over a long period of time by applying the gel lubricant to the sliding portion again.

The semi-solid gel lubricant and grease used in the present invention are prepared from a lubricant and a thickener comprising a base oil and optionally an additive.
As the base oil used for the lubricating oil, a lubricating base oil such as a mineral oil, a synthetic oil, an animal or vegetable oil can be used. Furthermore, these lubricating base oils may be used alone or in combination of two or more.
Mineral oil base oils include paraffin mineral oil and naphthene mineral oil, synthetic oil systems include poly-α-olefins, polybutenes, alkylbenzenes, esters, ethers, silicone oils, and animal and vegetable oil systems include beef tallow and whale oil. Examples include oil, soybean oil, rapeseed oil, palm oil, and modified oils thereof.

Among these base oils, a polar base oil is preferable because it forms a strong gel. Examples of such base oils include base oils such as ester-based, ether-based, or animal-plant systems, and base oils that are gelled with a polar gelling agent, and usually form a strong gel by hydrogen bonding.
In addition, it is more preferable that the base oil is biodegradable, assuming a case where a semi-solid gel lubricant mixed in water is discarded even if a small amount. As a standard for biodegradability, the certification standard for obtaining the “Eco Mark” certified by the Japan Environment Association is one guideline, and biodegradation is performed by the OECD method (OECD 301B, C, F or ASTM D5864, D6731). The degree is over 60%. Among the base oils, hydrocarbon oils such as mineral oils are not biodegradable, but most of esters, ethers having a specific structure, and animal and vegetable oils are biodegradable.

Preferably 8~1000mm ² / s as the kinematic viscosity at 40 ° C. of the base oil, 32~500mm ² / s is more preferable. When the viscosity of the base oil is too low, the coating film formed becomes thin and the lubricity becomes poor. When the viscosity of the base oil is too high, the gel fluidity is lost and the handling becomes difficult. The higher the flash point, the better from the viewpoint of safety, preferably 200 ° C or higher, more preferably 250 ° C or higher.

As additives to be added to the base oil, alkyl earth metal detergents, antiwear agents, extreme pressure agents, dispersants, antioxidants, rust inhibitors, conventionally used in lubricating oils, greases, etc. Additives such as metal deactivators and antifoaming agents can be added to improve performance.
Examples of the alkaline earth metal detergents include alkaline earth metals such as magnesium, calcium, and barium, and examples thereof include alkaline earth metal sulfonates, phenates, and salicylates. Examples of the antiwear agent include phosphate esters, acidic phosphate esters, phosphate ester amine salts, phosphite amine salts, zinc dialkyldithiophosphates, and the like.

  Other additives include sulfurized olefins and sulfurized fats and oils as extreme pressure agents, and polyalkenyl succinimides, polyalkenyl succinic acid esters and their respective boric acid modified products as dispersants. Antioxidants such as amine and phenolic antioxidants, metal deactivators such as benzotriazole, rust inhibitors such as alkenyl succinic acid esters or partial esters, antifoaming agents such as silicone compounds, etc. Respectively.

  In order to reduce the friction with the additive, that is, to reduce the friction coefficient, it is effective to add a friction modifier. The friction modifier is adsorbed on the sliding material, and its adsorption coating prevents organic metals such as esters, alcohols and amide compounds from reacting with the sliding member. There are metal-containing friction modifiers such as molybdenum compounds that reduce friction by forming a shear coating. Examples of the molybdenum compound include molybdenum disulfide, molybdenum dithiocarbamate, and molybdenum dithiophosphate. In particular, the addition of a molybdenum compound is effective, and the blending amount in the gel lubricant is preferably 0.5 to 20% by mass, more preferably 1 to 10% by mass. If the addition amount is too small, there is no effect of reducing friction, and if it is too much, the balance with other additives is deteriorated and the stability is lowered.

Of the thickeners that semisolidify lubricating oils containing additives in base oils, amide compounds are suitable as gelling agents for producing gel lubricants. As the amide compound, a fatty acid amide having one or more amide groups is preferable, and a monoamide having one amide group and a bisamide having two amide groups can be preferably used. Monoamide compounds include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, saturated fatty acid amides such as hydroxy stearic acid amide, unsaturated fatty acid amides such as erucic acid amide, stearyl stearic acid amide, oleyl oleic acid amide And amides substituted with a saturated or unsaturated long-chain fatty acid and a long-chain amine, such as oleyl stearamide. Usually, the fatty acid amide has 8 to 20 carbon atoms in the fatty acid moiety.
Examples of the bisamide compound include ethylene bis stearic acid amide, ethylene bis oleic acid amide, methylene bis lauric acid amide, hexamethylene bis oleic acid amide, hexamethylene bishydroxy stearic acid amide, m-xylene bis stearic acid amide and the like.

  The melting point of the amide compound is 50 to 300 ° C., preferably 100 to 200 ° C., and a compound having an appropriate melting point may be selected according to the use. In some cases, two or more amide compounds are mixed and melted. The temperature may be adjusted. The amide compound as a thickener is blended in an amount of 1 to 60% by mass, preferably 5 to 40% by mass, and more preferably 10 to 35% by mass with respect to the entire composition (gel lubricant). It is. The hardness of the finished gel lubricant depends on the blending amount of the gelling agent. If the blending amount is too small, the film formed is too soft and the formed film becomes thin. On the other hand, if it is too large, it becomes too hard and difficult to handle.

  Since the temperature at which the gel-like lubricant is liquefied is several degrees lower than the melting point of the gelling agent, the gelling agent is used so that the liquefaction temperature is higher than the temperature of the water lubricant in the sliding portion during use. It is desirable to select The temperature of the water lubricant in the sliding portion can be measured with a non-contact thermometer. Further, when the water lubricant is recycled, the temperature of the water lubricant flowing out from the sliding portion can be substituted.

In addition, the grease is semi-solid obtained by blending a lubricant with a thickener. As this thickener, a urea compound or a metal soap can be used.
Examples of the urea compound include a diurea compound, a triurea compound, a tetraurea compound, a urea / urethane compound, and the like, which can be appropriately used depending on the purpose.
Metal soap is a saponified carboxylic acid or ester thereof with a metal hydroxide such as an alkali metal or alkaline earth metal. Here, sodium, calcium, lithium, aluminum and the like are preferable as the metal, and the carboxylic acid is a crude fatty acid obtained by hydrolyzing fats and oils to remove glycerin, monocarboxylic acid such as stearic acid, and 12-hydroxystearic acid. Suitable are monohydroxycarboxylic acids such as dibasic acids such as azelaic acid, and aromatic carboxylic acids such as terephthalic acid, salicylic acid and benzoic acid. These may be used individually by 1 type, or may be used in combination of 2 or more type. Specifically, lithium soap is preferable, and lithium soap using 12-hydroxystearic acid is particularly preferable.

  The thickener is blended in an amount of 1 to 60% by mass, preferably 5 to 40% by mass, and more preferably 10 to 35% by mass with respect to the entire composition (grease). The hardness of the finished grease depends on the blending amount of the thickener. If the blending amount is too small, the film formed becomes too soft and the formed film becomes thin. On the contrary, if the blending amount is too large, it becomes too hard and difficult to handle.

  The water used in the present invention is not particularly limited, but it is preferable that the amount of dust, microorganisms, and metals is as small as possible. From this point, ion-exchanged water or distilled water is preferable. These waters are anti-wear agents such as water-soluble alcohols, carboxylic acids, and phosphoric acids, extreme pressure agents, and water lubricants with appropriate amounts of preservatives and antifungal agents added to prevent the generation of bacteria and soot. It can also be used.

A specific procedure for applying the lubrication method of the present invention to a sliding part is as follows. First, a semi-solid lubricant, particularly a gel lubricant is applied to the sliding material to form a gel lubricant coating. The application can be performed by an appropriate method conventionally used, and generally using a brush, a brush, a coater or the like. Gel lubrication with a method in which the temperature rises and the sliding material is immersed in a liquid gel lubricant and then taken out and cooled, or after spraying the liquid gel lubricant with a spray and then cooled An agent film may be formed.
To lubricate a sliding part covered with a gel lubricant with water as a lubricant, conventional methods of lubricating the sliding part with a liquid lubricant, for example, dripping, spraying, spraying, dipping, etc. The method may be applied by replacing the lubricating oil with water. It is preferable that the entire sliding portion is covered with water.

  The lubrication method of the present invention is a lubrication method that is lubricated with water, reduces wear, further reduces friction and improves efficiency, is safe and has low environmental load, and is used in a wide range of water lubrication applications. Can be usefully applied. The sliding material used in the machine is preferably a surface-treated material such as manganese phosphate treatment or zinc phosphate treatment in which pores exist, and a semi-solid gel lubricant is present in the pores. Since it penetrates, it becomes difficult to peel off, and the effect is maintained for a longer time.

  Hereinafter, the present invention will be described in more detail based on examples. In addition, this invention is not restrict | limited at all by the following examples.

(Preparation of gel lubricant)
Gel lubricants (Gel-1 to Gel-4) were prepared at the blending ratios shown in Table 1 using the following lubricant base oil, thickener (gelling agent), and additives. The blending ratio was expressed as mass% based on the whole composition.
(A) Base oil / paraffinic mineral oil base oil (kinematic viscosity (40 ° C.) 97 mm ² / s, viscosity index 98, pour point −12.5 ° C., flash point 274 ° C., VG100, manufactured by Japan Energy Co., Ltd.)
Polyol ester base oil (an ester of pentaerythritol with 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid (1: 1 in molar ratio), kinematic viscosity (40 ° C.) 69 mm ² / s, viscosity index 89 , Pour point -40 ° C, flash point 252 ° C, manufactured by NOF Corporation, VG68)
(B) Additive / tricresyl phosphate (TCP, DURAD TCP manufactured by Ajinomoto Co., Inc.)
Basic calcium sulfonate (LZ-74 manufactured by Nippon Lubrizol Co., Ca content: 12% by mass, base number: 305 mgKOH / g)
Molybdenum dithiocarbamate (MoDTC, Sakuralube 165 manufactured by ADEKA Corporation, Mo content 4.6% by mass, S content 5.1% by mass)
(C) Gelling agent / ethylene bisstearyl bisamide (melting point 145 ° C., reagent manufactured by Wako Pure Chemical Industries, Ltd.)
N-lauryl lauric acid amide (melting point 77 ° C., reagent manufactured by Wako Pure Chemical Industries, Ltd.)

[Grease and lubricating oil]
As the grease, commercially available JOMO lysonic grease No. 2 (lithium (Li) soap type) and JOMO urea grease No. 2 (urea type) were used. As the lubricating oil, commercially available “JOMO Hydrax A46” (mineral oil-based hydraulic oil) and “JOMO screw 32” (mineral oil-based air compressor oil) were used. Both are manufactured by Japan Energy.

〔water〕
As the water, purified water (purified water produced by distillation of water purified by an ion exchange method, reagent manufactured by Kyoei Pharmaceutical Co., Ltd.) was used as it was.

(Lubricity evaluation)
The four types of gel lubricants and two types of greases thus prepared were applied to test pieces as Examples 1 to 4 and Examples 5 to 6, respectively, and then lubricated in a purified water bath ( FALEX seizure load) was measured, and the coefficient of friction was measured using an Iwata-type pendulum type oiliness tester. The obtained results are shown in Table 2. On the other hand, as Comparative Examples, Comparative Examples 1, 2 and 3 measured the FALEX seizure load and the friction coefficient in the same manner as in Examples in water, hydraulic oil and compressor oil without using a gel-like lubricant. . In Comparative Examples 4 to 6, the FALEB seizure load and the friction coefficient were measured in the same manner by applying the gel lubricant without using water lubrication. The results of Comparative Examples 1 to 6 obtained are shown in Table 3.
(FALEX test)
Abrasion amount: With reference to ASTM D2670, a gel lubricant, grease or lubricating oil was applied to the V block, set in combination with pins, then immersed in a water bath and tested, and the seizure load was measured. The measurement was performed under conditions of a water temperature of 20 ° C., a rotation speed of 100 rpm, and a leveling operation (load 250 Lbf, 1 minute). However, only Comparative Example 4 was tested by putting oil in the tank.
(Iwata pendulum test)
The coefficient of friction was measured at room temperature using a Kamata pendulum type oiliness tester. Apply semi-solid gel lubricant, grease or lubricating oil to the roller pin, set the ball in the oil tank, put purified water in place of the oil and immerse it, and gently push the roller pin of the pendulum The friction coefficient was measured on the surface. However, about the comparative example 4, it was set as the test which put oil in the oil tank.
Note that Comparative Example 1 was not measured for equipment maintenance because seizure occurred during the FALEX test break-in and a high coefficient of friction was expected.

  As can be seen from Tables 2 and 3, the lubrication method of the present invention can be said to be a very good lubrication method because it can improve the seizure load and reduce the friction. In particular, when a gel lubricant is used as the coating lubricant of Examples 1 to 4, the seizure load is high and the friction coefficient is low, which is an excellent result and is excellent. Even when grease was used for application in Examples 5 and 6, the results were much better than the lubricating oils in Comparative Examples 2 and 3. When the lubricant of Comparative Example 1 was not applied, only a very low lubricity was shown. Only the gel lubricants of Comparative Examples 4 to 6 were used, and even when water was not used, only low lubricity was shown.

  The lubrication method of the present invention improves lubricity when there is a lot of wear on equipment and machinery only with lubrication with water, or when extreme pressure becomes a bottleneck in achieving energy saving and safety, which are the advantages of water lubrication. In addition, it is a method of reducing friction and improving efficiency, and can be usefully applied to a wide range of applications.

Claims (4)

  Sliding gel lubricant or grease obtained by blending 1-60 mass% of thickener with mineral oil, synthetic oil and / or animal and vegetable oils based on the total composition. A method of lubricating the sliding portion with water after being applied to the portion.   The lubricating method according to claim 1, wherein the thickener is an amide compound having a melting point of 50 to 300 ° C.   The lubrication method according to claim 1 or 2, wherein the liquefaction temperature of the semi-solid gel lubricant is higher than the water temperature in the sliding portion during operation.   The lubricating method according to any one of claims 1 to 3, wherein the base oil of the gel lubricant is biodegradable.