KR100900748B1 - Lubricant - Google Patents

Abstract

Aluminum or an aluminum material in contact with graphite or molybdenum disulfide using a perfluoropolyether oil having a kinematic viscosity at 50 ° C of 50 to 1500 mm ² / sec and containing no (CF ₂ O) _n group as a polymer repeating unit. Lubricant consisting of a lubricant or grease, characterized in that it is used for contact with. As the perfluoropolyether base oil, F (CF ₂ CF ₂ CF ₂ O) _m C ₂ F ₅ , RfO [CF (CF ₃ ) CF ₂ O] _p (CF ₂ CF ₂ O) _q Rf ′ is used. This lubricant is not significantly impaired in high temperature properties (high temperature durability) even when used for various purposes as described above. Moreover, when the base oil whose kinematic viscosity is 50-250 mm <^2> / sec is used, it is excellent also in low temperature characteristic.

Kinematic viscosity, base oils, lubricants, perfluoropolyethers, high temperature properties, grease

Description

Lubricant {LUBRICANT}

The present invention relates to a lubricant. More specifically, lubricating oil or grease used for contact with graphite or molybdenum disulfide, such as sintered oil-impregnated bearings containing graphite or molybdenum disulfide, or for contact with aluminum, such as a sliding member using aluminum. It relates to a lubricant made.

The sintered oil-impregnated bearing is composed of a porous body in which several kinds of solid powders are pressed by adding a solid lubricant graphite, molybdenum disulfide, carbon black and the like to metal powders such as iron, copper, tin and zinc. Sintered oil-impregnated bearings are used lubricated by self-lubrication by a small amount of lubricant impregnated initially. Therefore, it is important for the life of the bearing that the lubricant is kept long in the bearing by a sufficient amount and can be used stably.

Automotive bearings are increasingly using sintered oil-impregnated bearings that are cheaper than ball / roller bearings, and the lubricants used in these sintered oil-impregnated bearings are particularly important for their high temperature durability and low temperature properties. Are in a more demanding environment. For this kind of purpose, a lubricating oil composition using a perfluoropolyether oil as a base oil is used, and such base oil is also a perfluoro by contacting and coexisting with several kinds of metals or solid lubricants having a very large surface area. Polyether uranium is also unable to maintain stable high temperature characteristics depending on its structure.

Patent Document 1: Patent No. 2,595,583

In addition, although aluminum is light, its specific strength is high, and it can be obtained by alloying or processing it to obtain higher strength. Furthermore, since it has corrosion resistance, sliding parts, automobile parts, aviation / ship parts, home appliances, electric motors, etc. It is used for various purposes ranging from tools. They contribute to reducing the weight of various machines, increasing the working efficiency of high-speed rotating parts and sliding parts, and reducing fuel costs. Also in the parts using these aluminum materials, it is required that the lubricant used for them can stably maintain the outstanding performance.

Summary of the Invention

The inventors found that the high temperature properties of perfluoropolyether oils depend not only on their structure, but also on the fact that their high temperature properties are drastically degraded by contact with graphite or molybdenum disulfide, which is used as a component in sintered oil-impregnated bearings. Came out. In addition, it has been found that perfluoropolyether oil rapidly deteriorates high temperature characteristics even by contact with an aluminum material.

An object of the present invention is to contact graphite or molybdenum disulfide, such as sintered oil-impregnated bearings containing graphite or molybdenum disulfide, or use in contact with metal parts such as ball bearings containing graphite or molybdenum disulfide, and the like. The present invention also provides a lubricant in which high temperature characteristics (high temperature durability) are not significantly impaired, even when used, or even when used in contact with an aluminum material including the use of an aluminum material as a rotating member.

An object of the present invention is a kinematic viscosity at 40 ° C. of 50 to 1500 mm ² / sec, preferably 50 to 250 mm ² / sec, particularly preferably 65 to ²⁰⁰ mm ² / sec, and as a repeating unit of the polymer (CF ₂ O a) a lubricant characterized in that it is used in contact with graphite or molybdenum disulfide or in contact with an aluminum material, based on a perfluoropolyether oil containing no _n group. The lubricant may be in the form of either lubricant or grease. Here, as the perfluoropolyether base oil, a perfluoropolyether oil represented by the following general formula is used.

F (CF ₂ CF ₂ CF ₂ O) _m C ₂ F ₅

RfO [CF (CF ₃ ) CF ₂ O] _p (CF ₂ CF ₂ O) _q Rf '

Effects of the Invention

The high temperature properties (high temperature durability) of perfluoropolyether oils depend not only on their structure, but also on the high temperature properties of the fluoro oil impregnated bearings, which are rapidly degraded by contact with graphite or molybdenum disulfide. According to the invention, it is used for contact with graphite or molybdenum disulfide, such as sintered oil-impregnated bearings containing graphite or molybdenum disulfide, or for use in contact with metal parts, such as ball bearings containing graphite or molybdenum disulfide. Even in the case, a lubricant is provided in which the high temperature properties are not significantly impaired.

On the other hand, applications for use in contact with metal parts include an atmosphere in which graphite or molybdenum disulfide is scattered or mixed, for example, contact with graphite or molybdenum disulfide derived from a motor part such as a brush or a shaft. The atmosphere in which graphite or molybdenum disulfide is scattered or mixed is not limited to these cases.

In such a perfluoropolyether oil, having a kinematic viscosity of 50 to 1500 mm ² / sec at 40 ° C., even when used under high temperature conditions in excess of 150 ° C. in the presence of a solid lubricant such as graphite and molybdenum disulfide, it is volatile or stable over a long period of time. Maintenance and long life of the used parts can be achieved. In particular, perfluoropolyether oil having a kinematic viscosity of 50 to 250 mm ² / sec, preferably 65 to ²⁰⁰ mm ² / sec is also excellent in low temperature properties.

These lubricants are applied to all sliding forms including rotation, reciprocation, sliding, and swinging, such as sintered oil-impregnated bearings or bushes containing graphite or molybdenum disulfide, such as idle speed control, exhaust gas recirculation, or electronic throttle control. Applications requiring heat resistance, low temperature, and load resistance such as fuel injection devices, hub units, traction motors, alternators, etc., and abrasion resistance and low friction characteristics, such as power transmission devices, power wind motors, wipers, etc. Automotive use such as intended use; Information equipment applications requiring high speed, low friction coefficient, low outgas resistance, and the like represented by hard disk drives, flexible disk storage devices, compact disk drives, magneto-optical disk drives, and the like; Office equipment applications represented by LBP scanner motors and the like; The motor use etc. which are used also in the high temperature environment of other home appliances, an acoustic equipment article, etc. are mentioned, In addition, it is effectively applied also to the use used in the environment which graphite or molybdenum disulfide contacts or mixes.

In addition, the high temperature property (high temperature durability) of perfluoropolyether oil is sharply lowered even when used for contact with aluminum materials, including the use of aluminum materials as sliding members. Even in the case of the lubricant of the present invention, the high temperature properties are not significantly impaired. That is, even when the lubricant of the present invention is used under high temperature conditions of 150 ° C. or 200 ° C. under the coexistence of aluminum materials, it is possible to achieve volatility and stability over a long period of time, thereby exhibiting lubricity in various slidings, thereby achieving ultra-life of used parts. Can be.

In addition to these various applications, this lubricant is also used in bearings or bushes in plastic processing equipment, office equipment, copier heat rolls, construction machinery, machine tools, power tools, printing, bookbinding, paper processing machinery or chains used in these parts. Further, it is also used for lubrication of contact parts between sliding member objects such as rotary bearings, planar bearings, sintered bearings, gears, valves, cokes, oil seals, rolls, and electrical contacts.

1 is a graph showing the change over time of the weight loss rate at 200 ° C. in the presence of graphite or molybdenum disulfide of various perfluoropolyether base oils.

Implement the invention  for Best  shape

As the base oil, the kinematic viscosity at 40 ° C. (according to JIS K2283; corresponding to ASTM D445) is 50 to 1500 mm ² / sec, preferably 50 to 250 mm ² / sec, particularly preferably 65 to ²⁰⁰ mm ² / sec, and the polymer As the repeating unit of, one containing no (CF ₂ O) _n group is used. If late in Example 1 and measures the polyether significant change over time (rate of weight decrease of the oil) perfluoroalkyl of time as shown in the graph of Figure 1, hayeoteul value in a constant temperature bath at 200 ℃, as a repeating unit of the polymer (CF ₂ O) The change over time of the perfluoropolyether containing _n group is not particularly remarkable compared to other perfluoropolyether oils in the absence of graphite or molybdenum disulfide, but when graphite or molybdenum coexists, Is significantly remarkable, while the absence of (CF ₂ O) _n groups as repeating units is mild in characterization even in the presence of graphite or molybdenum disulfide, and thus perfluoro containing no (CF ₂ O) _n groups as repeating units. Polyether oils are used as base oils.

In addition, as shown in the results of the later Example 2, even in the presence of an aluminum material, the weight loss amount at a high temperature of 250 ° C. of the lubricant according to the present invention is within an acceptable range, and also in the kinematic viscosity at −40 ° C. .

Roneun as the polymer repeating units (CF ₂ O) _n which does not contain a group perfluoropolyether oils (base oils), for example are as follows.

(A) F (CF ₂ CF ₂ CF ₂ O) _m C ₂ F ₅

(B) RfO [CF (CF ₃ ) CF ₂ O] _p (CF ₂ CF ₂ O) _q Rf '
Here, Rf and Rf 'are the same or different C1-C5 perfluoroalkyl groups.

Perfluoropolyether oil (A): Anionic polymerization of 2,2,3,3-tetrafluorooxetane in the presence of cesium fluoride catalyst, resulting in fluorine-containing polyether (CH ₂ CF ₂ CF ₂ O) _n It is obtained by treating a fluorine gas under ultraviolet irradiation of -300 degreeC. It is possible to use a thing having a kinematic viscosity at 40 ° C in the range of ⁵ to 2000 mm ² / sec, which satisfies the condition of m = 2 to 100 in the general formula of the perfluoropolyether oil (A).

Perfluoropolyether oil (B): Hexafluoropropylene oxide or this and tetrafluoro by completely fluorination of hexafluoropropylene or a precursor produced by photo oxidation polymerization of this and tetrafluoroethylene or in the presence of a cesium fluoride catalyst. It is obtained by anionic polymerization of ethylene oxide and treatment of the acid fluoride compound having the terminal CF (CF ₃ ) COF group obtained with fluorine gas. It can be used that the kinematic viscosity at 40 ℃ in the range of 5 ~ 2000mm ² / sec, this is p + q = 2 ~ 200, q / p = 0 ~ 2 in the general formula of the perfluoropolyether oil (B) Satisfies the condition

However, if the kinematic viscosity is 50 or less, the evaporation loss rate (weight reduction rate) increases, and the oil film strength decreases, which may cause a decrease in life, abrasion, and abnormal engine stop. Not only does it become very high and cannot obtain sufficient low-temperature characteristics, but also it can cause harmful effects such as increased power consumption and torque due to an increase in viscosity resistance. Therefore, if the kinematic viscosity at 40 ° C is 50 to 1500 mm ² / sec, sufficient heat resistance stability is achieved. a and exhibits, in particular, for example, if the good low temperature properties required under a low temperature condition such as -40 ℃ has limited 50~250mm ² / sec, preferably 65~200 mm ² / sec perfluoropolyether euro . The perfluoropolyether oil having such kinematic viscosity not only satisfies sufficient evaporation loss characteristics or low temperature characteristics, but also enables stable use under high temperature conditions exceeding 200 ° C. However, two or more types of perfluoropolyether oils may be mixed and used, and in that case, the kinematic viscosity at 40 ° C of the mixed base oil may be within this range.

A thickening agent is added and used for such base oil, Preferably a fluororesin is used. As the fluororesin, a polytetrafluoroethylene, a tetrafluoroethylene-hexafluoropropene copolymer, a perfluoroalkylene resin and the like which have been conventionally used as a lubricant are used. Polytetrafluoroethylene produces polytetrafluoroethylene which has a number average molecular weight (Mn) of about 1000-1 million by the method of emulsion polymerization, suspension polymerization, solution polymerization, etc. of tetrafluoroethylene, and thermally decomposes it, The number average molecular weight (Mn) of about 1000-50000 is processed and processed by methods, such as electron beam irradiation decomposition and physical grinding | pulverization. Copolymerization reaction and low molecular weight treatment of tetrafluoroethylene and hexafluoropropene are also carried out in the same manner as in the case of polytetrafluoroethylene, and a number average molecular weight (Mn) of about 1000 to 600000 is used. do. On the other hand, the control of the molecular weight can be carried out using a chain transfer agent in the copolymerization reaction. The obtained powdered fluorine resin generally has an average primary particle size of about 500 μm or less, preferably about 0.1 to 30 μm. The addition of the powdered fluorine resin imparts oil film forming ability, splash resistance, leakage resistance, and rust resistance, and can further improve lubricity and durability.

As the thickener other than the fluorine resin, metal soaps such as Li soap, urea resins, minerals such as bentonite, organic pigments, polyethylene, polypropylene, polyamides, and the like can also be used. In view of heat resistance and lubricity, aliphatic dicar Acid metal salts, monoamide monocarboxylic acid metal salts, monoester carboxylic acid metal salts, diurea, triurea, tetraurea and the like are used.

Thickeners, such as these fluororesin powders, are added and mixed in the ratio of 0.1-40 weight%, Preferably it is 0.5-30 weight% of the whole composition which added the thickener to perfluoro polyether oil base oil. At higher addition ratios, the composition becomes too hard to be encapsulated in bearings and the like. On the other addition ratios below, the increase in fluorine resin is not exhibited, leading to a decrease in apparent viscosity and deterioration in dispersibility in base oil. It is not expected that the improvement of splash resistance, leakage resistance, and rust resistance will be sufficient. When the addition ratio of the thickener is about 10% by weight of the total amount with the base oil, grease is formed, and in the later examples and comparative examples, when the ratio of the thickener is 5% by weight or less, fluidity in the category of "liquid grease" As a result, the evaluation of the low temperature properties is shown as the low temperature viscosity of the base oil mixture. On the other hand, in the example where the proportion of the thickener is 30% by weight, since it becomes semi-solid in the category of grease, evaluation of the low temperature characteristic is shown as the evaluation result of the low temperature torque.

In addition, within the scope not impairing the object of the present invention, the ends of conventionally known fluorine-based additives, such as perfluoropolyether, may be selected from alcohols, carboxylic acids or esters thereof, amines, amides, phosphoric acids or esters thereof, phosphonic acids or The compound substituted by the reaction product of this ester, an isocyanate, alcohol, or an amine, etc. can also be mix | blended according to a use as needed.

By further adding fluorine resin to the base oil, various non-fluorine additives, viscosity index improvers, pour point depressants, ashless dispersants, metallic detergents, antioxidants, and rust inhibitors, which were conventionally incompatible with perfluoropolyether oils. Additives added to conventional lubricants such as corrosion inhibitors, antiseptics, extreme pressure agents, oily agents, friction modifiers and solid lubricants may be added as necessary.

Examples of the antioxidant include phenolic antioxidants such as 2,6-di-t-butyl-4-methylphenol and 4,4'-methylenebis (2,6-di-t-butylphenol), and carbon atoms. And amine antioxidants such as alkyldiphenylamine, triphenylamine, phenyl-α-naphthylamine, alkylated α-naphthylamine, phenothiazine, and alkylated phenothiazine having an alkyl group of ˜20.

Examples of the rust inhibitors include fatty acids, fatty acid amines, alkyl sulfonic acid metal salts, alkyl sulfonic acid amine salts, paraffin oxides, polyoxyethylene alkyl ethers, and the like. As corrosion inhibitors, for example, benzotriazole, benzoimidazole, and thiadiazole Etc. can be mentioned.

Examples of the extreme pressure agent include phosphorus compounds such as phosphoric acid esters, phosphorous acid esters, and phosphoric acid ester amine salts, sulfur compounds such as sulfides and disulfides, dialkyldithio phosphate metal salts, and dialkyldithio carbamic acid metal salts. have.

Examples of the oily agent include fatty acids or esters thereof, higher alcohols, polyhydric alcohols or esters thereof, aliphatic amines, fatty acid monoglycerides, and the like.

In addition, examples of the solid lubricant include graphite, molybdenum disulfide, nitrogen boron, nitrogen silane, and the like. In the case where graphite or molybdenum disulfide is used as the solid lubricant, the change in the heat resistance time of the perfluoropolyether base oil is reduced. It can prevent effectively.

The following preparation method is employ | adopted for preparation of the composition formed by adding a thickening agent to perfluoro polyether base oil, for example.

(a) A predetermined amount of a thickening agent is added to perfluoropolyether base oil, and it is knead | mixed fully with a 3 rolls or a high pressure homogenizer, (b) Perfluoropolyether oil in the reaction kiln which can be heated and stirred. Aliphatic carboxylic acid was added to heat and melt, and a predetermined amount of metal hydroxide (and amide compound or alcohol compound) was added thereto, followed by metal chloride reaction (and amidation reaction or esterification reaction), followed by cooling. The method of kneading sufficiently as a homogenizer or (c) perfluoropolyether oil and an isocyanate is added to the reaction kiln which can be heated and stirred, and it heats, a predetermined amount is added to it, it is made to react, it is three rolls, Or by sufficiently kneading with a high pressure homogenizer.

Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these Examples.

Example  One

Graphite powder (manufactured graphite powder CB-150 from Nippon Kokuen Co., Ltd .; 98.0% or more fixed carbon content, average particle diameter of 40 μm) or molybdenum disulfide (LM13-SM powder from Daito Honkatsu); 0.4 μm of the particle diameter) was mixed in an amount of 10% by weight in the sample, 0.6 g of this test sample was taken in a 37-mm glass shale, uniformly coated in a thin film form, and then left in a 200 ° C. thermostat. The change over time of the weight loss rate of the oil was measured.

The results obtained are shown in the graph of FIG.

●: F (CF ₂ CF ₂ CF ₂ O) _m C ₂ F ₅ (Kinematic viscosity at 40 ° C: 100 mm ² / sec)

○: + graphite

▲: RfO [CF (CF ₃ ) CF ₂ O] _p (CF ₂ CF ₂ O) _q Rf '(Kinematic viscosity: 180 mm ² / sec)

△: + graphite

■: RfO (CF ₂ CF ₂ O) _m (CF ₂ O) _n Rf '(Kinematic Viscosity: 160mm ² / sec)

□: + Graphite

◆: + Molybdenum Disulfide

From this result, in the perfluoropolyether oil containing no (CF ₂ O) _n group as the repeating unit of the polymer, the weight loss rate of the oil at 200 ° C. was hardly affected by the presence of graphite, In perfluoropolyether oils containing (CF ₂ O) _n groups as repeat units, it can be seen that almost all oils are evaporated and lost in a very short time due to the presence of graphite or molybdenum disulfide, in particular graphite.

Example  2

To the following perfluoropolyether base oils (A) or (B) having kinematic viscosity at various temperatures of 40 ° C, aluminum powder (from Wako Pure Chemical Co., Ltd .; purity: 99.5%, particle diameter: 53-150 μm) was added in an amount of 10% by weight in the sample. 0.6 g of the test sample was mixed with 37 mm diameter glass shale, uniformly applied in a thin film form, and then allowed to stand in a thermostat at 250 ° C. After 100 hours, the weight of the entire glass shale was measured. It measured and calculated the weight loss rate of an oil.

Perfluoropolyether oil (A): F (CF ₂ CF ₂ CF ₂ O) _m C ₂ F ₅

Kinematic Viscosity at 40 ℃

(A-1) 65 mm ² / sec

(A-2) 100mm ² / sec

(A-3) 200mm ² / sec

(A-4) 23mm ² / sec

Perfluoropolyether oil (B): RfO [CF (CF ₃ ) CF ₂ O] _p Rf '

Kinematic Viscosity at 40 ℃

(B-1) 180mm ² / sec

(B-2) 400 mm ² / sec

(B-2) 25mm ² / sec

(B-4) 1200mm ² / sec

Perfluoropolyether oil (C): RfO (CF ₂ CF ₂ O) _m (CF ₂ O) _n Rf '

Kinematic Viscosity at 40 ℃

140 mm ² / sec

On the other hand, as the fluororesin powder, emulsion polymerization polytetrafluoroethylene powder (Mn of about 50000 to 100000, average primary particle diameter of 0.2 µm) was used.

The results obtained are based on the type and amount of the base oil (parts by weight) and the amount of the fluororesin (parts by weight), and 40 ° C kinematic viscosity and pour point (according to JIS K2269; ASTM D97 correspondence), oil ( The weight loss rate of the base oil) and the low temperature viscosity (according to JIS K2283, kinematic viscosity at −40 ° C .; corresponding to ASTM D445) are shown in Table 1 below. On the other hand, No. 1-12 are Examples, and No. 13-15 is a comparative example.

From the above results, it can be seen that the weight reduction rate at 250 ° C. is remarkably increased when the one having a 40 ° C. kinematic viscosity of less than 50 mm ² / sec is used (No. 13, 14). In addition, it can be seen that the discard is the weight loss after 250 ℃, 100 sigan large majority of the sample is lost when as the polymer repeating units used in that it comprises an _{n (CF 2 O) (No. 15} ). On the other hand, in the 40 degreeC kinematic viscosity in the range of 50-1500 mm <^2> / sec, the weight loss amount at the high temperature of 250 degreeC is in the allowable range, and the 40 degreeC kinematic viscosity in the range of 50-250 mm <^2> / sec is -40 degreeC The same applies to kinematic viscosity at (No. 1 to 10).

In addition, A-1 70 weight part-fluorine resin 30 weight part (No. 21), A-2 70 weight part-fluorine resin 30 weight part (No. 22), B-2 70 weight part-fluorine resin 30 weight part For grease consisting of (No. 23) and B-3 70 parts by weight-30 parts by weight of fluorine resin (No. 24), in addition to the above items, the low temperature torque test (according to JIS K2220.5.14, when starting at -40 ° C and The value at normal time was measured; corresponding to ASTM D1478. The results obtained are shown in Table 2 below. On the other hand, No. 24 is a comparative example.

Claims (18)

It is used for contacting with aluminum materials using a perfluoropolyether oil having a kinematic viscosity at 40 ° C of 50 to 1500 mm ² / sec and containing no (CF ₂ O) _n group as a repeating unit of the polymer. Characterized in that the lubricant. The lubricant according to claim 1, wherein a perfluoropolyether oil having a kinematic viscosity at 40 ° C of 50 to 250 mm ² / sec is used as the base oil. The perfluoropolyether base oil is a general formula according to claim 1 F (CF ₂ CF ₂ CF ₂ O) _m C ₂ F ₅ Wherein m is an integer from 2 to 100, and the perfluoropolyether oil (A) and the general formula RfO [CF (CF ₃ ) CF ₂ O] _p (CF ₂ CF ₂ O) _q Rf ' Where Rf and Rf 'are the same or different perfluoroalkyl groups of 1 to 5 carbon atoms, p + q = 2 to 200, q / p = 0 to 2 and q may be 0, CF (CF ₃ ) The lubricant, characterized in that at least one of the perfluoropolyether oil (B) represented by the CF ₂ O group and CF ₂ CF ₂ O group is randomly bonded in the main chain). The perfluoropolyether base oil is a general formula according to claim 2 F (CF ₂ CF ₂ CF ₂ O) _m C ₂ F ₅ Wherein m is an integer from 2 to 100, and the perfluoropolyether oil (A) and the general formula RfO [CF (CF ₃ ) CF ₂ O] _p (CF ₂ CF ₂ O) _q Rf ' Where Rf and Rf 'are the same or different perfluoroalkyl groups having 1 to 5 carbon atoms, p + q = 2 to 200, q / p = 0 to 2 and q may be 0, and CF (CF ₃ ) The lubricant, characterized in that at least one of the perfluoropolyether oil (B) represented by the CF ₂ O group and CF ₂ CF ₂ O group is randomly bonded in the main chain). The lubricant according to claim 1, wherein the lubricant is a lubricant. The lubricant according to claim 2, wherein the lubricant is a lubricant. The lubricant according to claim 1, wherein the thickener is further mixed and used as grease. The lubricant according to claim 7, wherein the thickener is a fluororesin powder. The lubricant according to claim 2, wherein the thickener is further mixed and used as grease. The lubricant according to claim 9, wherein the thickener is a fluororesin powder. delete delete delete delete delete delete The lubricant according to claim 1, which is used for the use of an aluminum material as the sliding member. The lubricant according to claim 2, which is used for the use of an aluminum material as the sliding member.

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