JP2005232433A - Grease composition for electrical contact - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease composition for an electrical contact excellent in sulfide-resistance of the contact and in improving effect of stability of contact resistance and further improved in heat stability, storage stability or the like. <P>SOLUTION: The grease composition for an electrical contact contains against 100 pts.wt. of (A) a polyorganosiloxane having a viscosity at 25°C of 10-100,000 mPa s, 0.1-30 pts.wt. of (B) a thickener, 0.01-3 pts.wt. of (C) an organomercaptan, and 0.01-3 pts.wt. of (D) sulfurized oil and fat that are processed with a fine-powdered active carbon. As the component (A), a polyorganosiloxane represented by general formula: [R<SP>1</SP><SB>a</SB>SiO<SB>(4-a)/2</SB>]<SB>n</SB>may be used. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a silicone grease for electrical contacts used for contacts of electronic devices and the like.

  Conventionally, greases based on silicone oil (polyorganosiloxane) have been used as greases for electrical contacts in electrical and electronic equipment, as well as mineral oil greases, synthetic oil greases such as polyether and diester. Yes. Since such silicone grease has good electrical properties and chemical stability and can be used in a wide temperature range, the amount used has increased in recent years.

  It improves the sulfidation resistance and contact stability of the silver contact grease, prevents a phenomenon called "galling" that prevents the switch from returning at a light load contact pressure, and operates a contact with high contact pressure such as volume. As a grease that can extend the service life, a combination of a silicone-based extreme pressure lubricant and a mercaptan-based rust preventive agent has been proposed. (For example, see Patent Document 1)

  However, in such electrical contact grease, since the sulfur-based extreme pressure lubricant contains impurities such as unreacted sulfur and hydrogen sulfide, the effect of the rust preventive agent is not fully exhibited, and the contact portion There was a problem that the silver coated on the surface of phosphor bronze or white bronze was corroded.

  That is, aliphatic mercaptan, which is a rust preventive agent, has a problem of being highly reactive and being oxidized over time to change into organodisulfide having a poor rust preventive effect. There is a problem that it occurs in a short period of time when mercaptans and sulfur-based extreme pressure lubricants coexist. In addition, it is thought that this is because the impurity (CuS) in the sulfurized fat or oil which is a sulfur-based extreme pressure lubricant promotes the deterioration of the rust preventive agent with time.

  In addition, since the aliphatic mercaptan, which is a rust preventive agent, is easily oxidized to disulfide, not only the melting point of the grease rises, but also when the fluororesin fine particles that are solid lubricants are blended in the grease, disulfide May be precipitated around fine particles such as fluororesin, which is one of the causes of shortening the product life.

  In order to solve such a problem, various methods for removing impurities in the sulfurized fat and oil have been proposed. For example, a method has been proposed in which sulfurized fats and oils are heated to 50 to 120 ° C. under atmospheric pressure and air or nitrogen gas is blown to remove remaining hydrogen sulfide. (For example, see Patent Document 2)

  In addition, a method in which a gas containing dissolved oxygen is blown and a desulfation catalyst such as basic copper carbonate is used in combination has been proposed. (For example, see Patent Document 3)

  However, in the method described in Patent Document 2, it takes a very long time to remove impurities, and the efficiency is poor. Moreover, in the method described in Patent Document 3, although the treated catalyst is removed by filtration, the copper sulfide produced by the reaction with the impurities is a fine particle, so it remains in the system without being completely removed. This has the problem of adversely affecting the properties of the contact grease.

Furthermore, conventional greases containing sulfurized fats and oils, which are sulfur-based extreme pressure lubricants, are not sufficiently heat stable, and the base polymer silicone oil (polyorganosiloxane) is decomposed by heating and becomes volatile. The content of a high-molecular-weight low-molecular siloxane component (low-molecular silicone compound) increases. For this reason, there has been a problem that the low-molecular siloxane that has volatilized adheres to the contact portion and a contact failure tends to occur.
JP-A-57-195198 Japanese Patent Publication No. 2-9640 JP-A-9-1000048

  The present invention has been made to solve these problems, and is excellent in the effect of improving the sulfidation resistance and contact resistance stability of contacts, and further improved in thermal stability and storage stability. The purpose is to provide grease.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have previously treated sulfur oils and fats, which are sulfur-based extreme pressure lubricants, with finely powdered activated carbon to remove impurities such as CuS. As a result, it was found that even when this was used in combination with an organomercaptan-based rust preventive agent, the silver in the contact portion was not corroded and no white precipitate was formed during storage, and the present invention was completed. It was.

  The grease for electrical contacts of the present invention comprises (A) 0.1 to 30 parts by weight of a thickener, with respect to 100 parts by weight of polyorganosiloxane having a viscosity at 25 ° C. of 10 to 100,000 mPa · s, It contains 0.01 to 3 parts by weight of (C) organomercaptan and 0.01 to 3 parts by weight of sulfurized fat and oil treated with (D) finely powdered activated carbon.

  According to the grease for electrical contacts of the present invention, the sulfidation resistance of contacts and the stability of contact resistance are improved. Moreover, this grease is excellent in thermal stability, and low-molecular siloxane components having high volatility are rarely generated by heating. Therefore, the occurrence of contact failure due to the low molecular siloxane is prevented. Furthermore, the storage stability is good, and even when stored for a long period of time, no precipitate is generated, and the operability of the contact can be stably improved.

  Embodiments of the present invention will be described below.

  In the embodiment of the grease for electrical contacts of the present invention, (A) 100 parts by weight of a polyorganosiloxane having a viscosity of 10 to 100,000 mPa · s at 25 ° C. is used. Parts, (C) 0.01 to 3 parts by weight of organomercaptan, and (D) 0.01 to 3 parts by weight of sulfurized fat and oil refined with finely powdered activated carbon.

  In the embodiment of the present invention, the component (A) is a polyorganosiloxane having a viscosity at 25 ° C. of 10 to 100,000 mPa · s, more preferably 20 to 10,000 mPa · s, and constitutes the main component of grease.

  When the viscosity of the polyorganosiloxane (A) is less than 10 mPa · s, not only is the volatility too high, but the resulting grease is liable to flow, causing an accident due to contact wear and the like, which is not preferable. On the other hand, when the viscosity exceeds 100,000 mPa · s, the viscosity resistance of the grease becomes too large, and the lubricity of the contact is liable to be adversely affected.

In addition, the highly volatile low-molecular-weight siloxane component contained in the polyorganosiloxane is volatilized from the applied contact parts and burned by sparks generated at other relays and motor contacts in the surroundings, and thus generated. Insulating inorganic silica tends to cover the terminal surface of the contact portion. In order to prevent the occurrence of contact failure due to such factors, it is desirable to use the polyorganosiloxane of component (A) from which the volatile low molecular siloxane component contained has been removed in advance. More specifically, the total content of cyclic silicone components (D ₄ , D ₅ , D ₆ , D ₇ , D ₈ , D ₉ and D ₁₀ components), which are low-molecular siloxanes with high volatility, is 1000 ppm. More preferably, it is 300 ppm or less. D represents a bifunctional siloxy unit represented by the general formula: (CH ₃ ) ₂ SiO.

As the component (A), a silicone oil represented by the general formula: [R ¹ _a SiO _{(4-a) / 2} ] _n can be used.

Here, the organic group R ¹ bonded to the silicon atom is a monovalent group selected from the group consisting of an alkyl group having 1 to 30 carbon atoms, a halogenated phenyl group, an alkenyl group, an aryl group, and an aralkyl group. When the carbon number of the alkyl group exceeds 30, the viscosity becomes high and inconvenience occurs in handling. Specifically, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, nonyl machine, alkyl group such as decyl group, dodecyl group, alkenyl group such as allyl group, phenyl group And aryl groups such as chlorinated phenyl groups, brominated phenyl groups, and halogenated phenyl groups such as iodinated phenyl groups, and aralkyl groups such as 2-phenylethyl and 2-phenylpropyl. These may be the same as or different from each other.

  A in the formula is a number in the range of 1.9 to 2.7. If the value of a is less than 1.9, the grease becomes too hard to be used, and if it is greater than 2.7, the optimum viscosity range cannot be obtained. Furthermore, n in the formula is a positive number, and is a number that satisfies the desired viscosity (10 to 100,000 mPa · s) as the component (A). Further, the component (A) may be a mixture of polyorganosiloxanes having different n.

As the molecular structure, the main component is a diorganosiloxane unit, which may contain a monoorganosiloxane unit and a silicate (SiO ₂ ) unit, and whose molecular ends are blocked with a triorganosilyl group. It is.

または一般式：

（ただし、Ｒ^２は炭素数１〜１８のアルキル基およびアルケニル基から成る群より選ばれる１価の炭化水素基、Ｒ^３は炭素数３以下のアルキル基、フェニル基から成る群より選ばれる1価の炭化水素基をそれぞれ示す。ｍは正数である。)で表わされるポリオルガノシロキサンの脂肪酸エステルを配合することができる。 When the silicone oil represented by the above general formula is used as the component (A), (E) the general formula:

Or general formula:

(Wherein R ² is a monovalent hydrocarbon group selected from the group consisting of an alkyl group having 1 to 18 carbon atoms and an alkenyl group, and R ³ is selected from the group consisting of an alkyl group having 3 or less carbon atoms and a phenyl group 1 A polyvalent hydrocarbon group, m being a positive number).

Examples of R ² in the formula include an alkyl group having 1 to 18 carbon atoms such as a stearyl group, an alkenyl group such as a vinyl group and an allyl group, and R ³ represents R in the average formula representing the component (A). The same group as ¹ is illustrated.

  Such (E) fatty acid ester not only helps to stabilize the contact resistance of silicone grease, improve lubricity, and restore the contact point, but also has a function of preventing the flow of grease. It also contributes to secure retention.

  The amount of component (E) added is desirably 1.0 to 50 parts by weight, more preferably 5 to 20 parts by weight, based on 100 parts by weight of component (A). If the addition amount is less than 1.0 part by weight, the effect of addition is not recognized. On the other hand, if it exceeds 50 parts by weight, the effect is not increased even if it is added more than that, and the discoloration of the contact is improved From the point of view, no better results can be obtained.

  The thickener of the component (B) used in the embodiment of the present invention imparts an appropriate consistency to the silicone oil that is the component (A), and examples thereof include silica fine particles, metal soaps, diurea compounds and the like. The

  Examples of the metal soap include laurates such as aluminum, zinc, manganese, lithium and potassium, myristate, palmitate, stearate and oleate. These may be used alone or in combination.

  The diurea compound is a compound having two urea groups (—NHCONH—) in the molecule, and is obtained by reaction of diisocyanate and amine. Examples of the diisocyanate include phenylene diisocyanate, tolylene diisocyanate, diphenyl diisocyanate, hexane diisocyanate, decane diisocyanate, and the like. Examples of amines include stearylamine, octylamine, dodecylamine, hexadecylamine, aniline, cyclohexylamine, diphenylamine and the like.

Silica fine powder has the effect of increasing the viscosity of the liquid, and also has the effect of polishing and cleaning the insulating material produced by oxidation and sulfidation of the surface of the contact portion, and has a specific surface area of 50 m ² / g or more is used. If the specific surface area is smaller than this, contact wear tends to occur. Examples of such silica fine powder include fumed silica, silica airgel, and precipitated silica. You may use what carried out the surface treatment of these silica fine powders with organosilane, polyorganosiloxane, organosilazane, etc.

  The silica fine powder is preferably added in the range of 0.1 to 10 parts by weight per 100 parts by weight of component (A). If the amount of silica fine powder added is less than 0.1 parts by weight, there is no effect of polishing and cleaning the surface of the contact point, resulting in poor contact. On the other hand, when the amount is more than 10 parts by weight, the apparent viscosity increases, and not only can the operation of the contact not be followed, but also the lubricity deteriorates and the lubrication life is impaired. By selecting an appropriate addition amount, a stable contact resistance can be provided even at a contact having a low contact pressure.

  Moreover, the compounding quantity of the whole thickener which is (B) component including such silica fine powder shall be 0.1-30 weight part with respect to 100 weight part of (A) component, More preferably, it is 1- 15 parts by weight. When the blending amount of the (B) thickener is less than 0.1 parts by weight, an appropriate consistency cannot be obtained, the grease tends to flow, and it is difficult to hold the grease at the contact part over a long period of time. When the blending amount exceeds 30 parts by weight, the consistency becomes too large, and it becomes difficult to apply grease to the contact part. Also, the lubricity is lowered, and the surface of the contact is polished more than necessary, which may cause a contact failure, which is not preferable.

  The organomercaptan which is the component (C) used in the embodiment of the present invention is a rust preventive agent for preventing oxidation / sulfurization of the silver surface which is a constituent material of the contact, and has 10 to 24 carbon atoms, more preferably 18 carbon atoms. A saturated or unsaturated aliphatic mercaptan in the range of ~ 22 is selected.

  Examples of such an organomercaptan include dexyl mercaptan, dodecyl mercaptan, cetyl mercaptan, lauryl mercaptan, stearyl mercaptan, isostearyl mercaptan, oleyl mercaptan, eicosyl mercaptan, docosyl mercaptan, and the like. One kind may be used alone, or two or more kinds may be used in combination.

  Aliphatic mercaptans having less than 10 carbon atoms are not suitable because they are not only insufficient in sulfidation resistance but also have a low vapor pressure, and thus easily volatilize indoors. In addition, saturated or unsaturated aliphatic mercaptans having more than 24 carbon atoms have extremely poor solubility with the polyorganosiloxane as the component (A) and are difficult to uniformly disperse in the silicone grease. Furthermore, silicone grease containing a higher aliphatic mercaptan having more than 24 carbon atoms tends to have extremely unstable contact resistance. In addition, since alkyl mercaptan having an odd number of carbon atoms is difficult to obtain industrially, it is particularly preferable to use stearyl mercaptan in view of easy handling.

  The amount of (C) organomercaptan added is 0.01 to 3 parts by weight, more preferably 0.03 to 0.5 parts by weight, based on 100 parts by weight of component (A). (C) If the addition amount of organomercaptan is less than 0.01 weight part, the antirust effect by addition is not fully acquired. Moreover, when the addition amount exceeds 3 parts by weight, not only the contact resistance of the grease becomes extremely unstable at a temperature of 0 ° C. or lower, but also there is a risk of poor conductivity.

  The component (D) in the embodiment of the present invention is an essential component for extending the lubrication life of the contact as a sulfur-based extreme pressure lubricant, and the sulfurized fat and oil purified by removing impurities with finely powdered activated carbon. Is used. Sulfurized oils and fats are sulfides obtained by reacting animal oils, vegetable oils, or olefins with sulfur.

  As the activated carbon for purifying such sulfurized fats and oils and removing impurities in the fats and oils, fine powders having an average particle size of 105 μm or less (150 mesh or less) are used. As a commercial item, there exists activated carbon (powder charcoal for water purification) made from Tsurumi Coal, for example. If the activated carbon has a large particle size (for example, 32 mesh or less and an average particle size of 500 μm), the effect of removing impurities cannot be sufficiently improved.

  As a treatment method, it is possible to adopt a known method of removing impurities by adsorbing with activated carbon, such as adding activated carbon in fine powder form, stirring and mixing while heating, if necessary, and filtering to remove the activated carbon. it can.

  The degree of purification treatment using activated carbon can be known, for example, by measuring the amount of Cu in the sulfurized fat and oil by ICP (high frequency inductively coupled plasma) analysis and calculating the amount of CuS as an impurity. It is preferable that the amount of CuS in the sulfurized fat after the treatment is not more than the measurement sensitivity by the ICP analysis method.

  (D) Addition amount of the sulfurized fat and oil treated with activated carbon as component is 0.01 to 3 parts by weight, more preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of component (A). . When the amount of component (D) is less than 0.01 parts by weight, the effect of addition is not recognized. That is, a phenomenon called “galling” in which lubricity cannot be obtained at a high temperature and the switch does not return when the switch is pressed tends to occur. When the addition amount exceeds 3 parts by weight, very good operability can be obtained at a high temperature, but the silver contact part tends to corrode and the contact resistance becomes unstable, which is not preferable. Moreover, since use under a wide range of temperatures, which is a characteristic of silicone grease, is significantly impaired, it is not preferable.

  In the embodiment of the present invention, a fluororesin fine powder can be further blended in addition to these components. The fluororesin fine powder has a function as a solid lubricant and functions to improve initial sliding properties. As the fluororesin fine powder, those having an average particle diameter of 0.05 to 50 μm are preferably used. Those having an average particle diameter of 0.05 μm are difficult to obtain industrially. On the other hand, if the average particle diameter exceeds 20 μm, the contact resistance of the contact is deteriorated, which is not preferable.

  The addition amount of the fluororesin fine powder is suitably in the range of 0.01 to 30 parts by weight, more preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of component (A). When the addition amount of the fluororesin fine powder is less than 0.01 parts by weight, the effect of improving the lubricity cannot be sufficiently obtained. On the other hand, when the amount exceeds 30 parts by weight, the contact resistance of the contact deteriorates, which is not preferable.

  The electrical contact grease according to the embodiment of the present invention can improve the sulfidation resistance of the contact and the stability of the contact resistance. Moreover, it is excellent in thermal stability and hardly generates a low molecular siloxane component by heating. Furthermore, the storage stability is good, no deposits are observed even after long-term storage, and the effect of improving the operability of the contacts is not reduced.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to a following example. In the examples, “parts” means parts by weight, and all viscosities are values at 25 ° C.

Examples 1-6
Sulfuric fats and oils that are sulfur-based extreme pressure lubricants are fats and oils obtained by reacting sulfur at a high temperature of 120 to 180 ° C. with animal fats and oils consisting of myristic acid, palmitic acid, stearic acid, oleic acid and linoleic acid. By treating with basic copper carbonate, unreacted sulfur was precipitated as copper sulfide, and this was removed by filtration. This sulfurized fat (S-1) was a black liquid having a viscosity of 3200 mPa · s.

  Next, this sulfurized fat (S-1) was refined with activated carbon. That is, 100 g of the above-mentioned sulfurized fat (S-1) was weighed into a 1 L flask equipped with a cooling pipe and a stirring device, diluted with 300 g of toluene, and then finely powdered activated carbon (Tsurumi Co., Ltd. water purification grade) PA) 100 g was added and mixed with stirring while heating at 80 ° C. for 24 hours. After stirring, the activated carbon was removed by suction filtration with filter paper. Further, the filtered toluene solution was transferred to a flask, heated to 60 ° C. with a rotary evaporator to remove toluene, and purified sulfurized fats and oils. The sulfurized fat (S-2) thus obtained was a brown liquid with a viscosity of 5600 mPa · s.

  Moreover, when the amount of Cu in the sulfurized fat (S-2) subjected to purification treatment with activated carbon was measured by ICP analysis and the amount of CuS as an impurity was calculated, it was below the measurement sensitivity.

  Next, polyorganosiloxanes (F-1) to (F-5) shown in Table 1 were prepared as base oils. These base oils and fatty acid esters of polyorganosiloxane (F-6), silica fine particles as a thickener, fluororesin fine particles (average particle size 0.3 μm), rust preventive (stearyl mercaptan), and the refined sulfurized fats and oils Each component was charged into a kneader with the composition shown in Table 2 to prepare a grease. The viscosity of the obtained grease was as shown in Table 2.

で表されるポリオルガノシロキサンの脂肪酸エステルであり、３０ｍＰａ・ｓの粘度（２５℃）を有する。また、シリカ微粒子としては、オクタメチルシクロテトラシロキサンで表面処理をした、比表面積２００ｍ^２／ｇの煙霧質シリカを用いた。 (F-6) is the chemical formula:

It has a viscosity (25 ° C.) of 30 mPa · s. Further, as silica fine particles, fumed silica having a specific surface area of 200 m ² / g, which was surface-treated with octamethylcyclotetrasiloxane, was used.

Comparative Example 1
Grease was prepared with the composition shown in Table 2 using sulfurized fat (S-1) that had not been purified by activated carbon. The viscosity of the obtained grease was 6000 mPa · s. In addition, by measuring the amount of Cu by ICP analysis, the amount of CuS, which is an impurity in the sulfurized fat (S-1) that has not been subjected to purification treatment with activated carbon, was calculated and found to be 2300 ppm.

Comparative Example 2
In a 2 L flask equipped with a condenser and a stirrer, 100 g of sulfurized fat (S-1) not subjected to activated carbon treatment was weighed and diluted with 300 g of toluene, and then hydrotalcite compound (Mg _0.7 Al _{0 .3} O _1.15 ) (Kyowa Chemical Industry Co., Ltd., KW-2000) powder was added, and the mixture was heated and mixed at 60 ° C. for 24 hours. After stirring for a predetermined time, suction filtration with a filter paper was performed to remove the hydrotalcite compound powder. Subsequently, the filtered toluene solution was transferred to a flask, heated to 60 ° C. with a rotary evaporator to remove toluene, and purified sulfurized fats and oils. The obtained sulfurized oil (S-3) was a brown liquid having a viscosity of 3300 mPa · s.

  Using the thus obtained sulfurized fat (S-3), a grease was prepared with the composition shown in Table 2. The viscosity of the obtained grease was 6000 mPa · s.

Comparative Example 3
In a 1 L flask equipped with a condenser and a stirrer, 100 g of sulfurized fat (S-1) not subjected to activated carbon treatment was weighed and diluted with 300 g of toluene, and then a chelate fiber (manufactured by Kirest Co., Ltd., Kirest Fiber). IRY) 20 g was added and mixed by heating at 40 ° C. for 24 hours. After stirring for a predetermined time, suction filtration with a filter paper was performed to remove the chelate fiber. Subsequently, the filtered toluene solution was transferred to a flask, heated to 60 ° C. with a rotary evaporator to remove toluene, and purified sulfurized fats and oils. The obtained sulfurized oil (S-4) was a brown liquid having a viscosity of 4000 mPa · s.

  Using the thus obtained sulfurized fat (S-4), grease was prepared with the composition shown in Table 2. The viscosity of the obtained grease was 6000 mPa · s.

Comparative Example 4
A 1 L flask equipped with a condenser and a stirrer was weighed 100 g of sulfurized fat (S-1) that had not been subjected to activated carbon treatment, diluted with 300 g of toluene, and then granulated silica alumina gel (Shinagawa Kasei Co., Ltd.) 50 g of Secard K-3) was added and mixed by heating at 50 ° C. for 24 hours. After stirring for a predetermined time, suction filtration with a filter paper was performed to remove the silica alumina gel. Subsequently, the filtered toluene solution was transferred to a flask, heated to 60 ° C. with a rotary evaporator to remove toluene, and purified sulfurized fats and oils. The obtained sulfurized oil (S-5) was a brown liquid having a viscosity of 3400 mPa · s.

  Using the thus obtained sulfurized fat (S-5), greases were prepared with the compositions shown in Table 2. The viscosity of the obtained grease was 6000 mPa · s.

Comparative Example 5
Grease was prepared with the composition shown in Table 2 without blending a rust inhibitor and sulfurized fat. The viscosity of the obtained grease was 6000 mPa · s.

Comparative Example 6
Grease was prepared with the composition shown in Table 2 without blending sulfurized fats and oils. The viscosity of the obtained grease was 5500 mPa · s.

  Next, using the silicone grease obtained in each of Examples 1 to 6 and Comparative Examples 1 to 6, the change in operating force of a switch contact with a contact load of 10 g obtained by plating silver on phosphor bronze to a thickness of about 3 μm was measured. . Moreover, the silver plate corrosion test was done. That is, a plate obtained by plating silver with phosphor bronze to a thickness of about 3 μm was cut into a size of 2 cm × 5 cm and immersed in grease at 85 ° C. for 24 hours to examine the degree of discoloration on the surface.

  Furthermore, the storage stability of the grease was examined. That is, 500 g from the silicone grease obtained in Examples 1 to 6 and Comparative Examples 1 to 6 was weighed into a 1 L plastic container and allowed to stand at room temperature in a cool and dark place for a predetermined time. Was observed. Furthermore, the change in the operating force of the switch contact was measured in the same manner as described above for the grease thus left for one year. These measurement results are shown in Table 2.

In addition, the silicone grease obtained in Example 1 and Comparative Example 1 was subjected to a heating acceleration test to examine thermal stability. In the heating acceleration test, the silicone greases of Example 1 and Comparative Example 1 were heated in a closed system at 80 ° C. for 7 days, respectively, and D ₄ , D ₅ , D ₆ , D ₇ , D ₈ , which are volatile low molecular siloxanes. , D ₉ and D ₁₀ , and the total of these contents was measured. For the silicone grease of Comparative Example 1, the content of low molecular siloxane after heating at 80 ° C. for 1 day was also measured. The measurement results for the silicone grease of Example 1 are shown in FIG. 1, and the measurement results for the silicone grease of Comparative Example 1 are shown in FIG.

From these measurement results, in the silicone grease of Comparative Example 1, decomposition of the base oil (polyorganosiloxane) proceeds by heating, and a cyclic silicone component (D ₄ , D ₅ , D), which is a low-molecular siloxane with high volatility. ₆ , D ₇ , D ₈ , D ₉ and D ₁₀ components) are significantly increased. Generation | occurrence | production of these cyclic silicones means that the principal chain of polyorganosiloxane which is base oil is cut | disconnected.

  On the other hand, in the silicone grease of Example 1, the generation of low molecular siloxane by heating is hardly observed. This is because, in the silicone grease of Example 1, the sulfurized fat (S-2) refined by activated carbon is blended, and CuS which is an impurity in the sulfurized fat is almost completely removed. This is considered to be because decomposition due to heating is suppressed.

  According to the grease for electrical contacts of the present invention, the sulfidation resistance and contact resistance stability of the contact are improved, and the operability of the contact is stably improved. Moreover, it is excellent in thermal stability, and the production of low-molecular siloxane components having high volatility by heating is small. Furthermore, it is excellent in storage stability, and precipitates are not generated even when stored for a long period of time, and the effect of improving the operability of the contact does not deteriorate. Therefore, it is suitable as a grease for lubricating silver contacts of electrical and electronic equipment.

It is a graph which shows the change of content of a low molecular siloxane component at the time of heating the silicone grease obtained in Example 1 of this invention. It is a graph which shows the change of content of a low molecular siloxane component at the time of heating the silicone grease obtained by the comparative example 1. FIG.

Claims (5)

  (A) With respect to 100 parts by weight of polyorganosiloxane having a viscosity at 25 ° C. of 10 to 100,000 mPa · s, (B) 0.1 to 30 parts by weight of thickener and (C) organomercaptan 0.01 to An electrical contact grease comprising 3 parts by weight and (D) 0.01 to 3 parts by weight of a sulfurized fat and oil treated with finely powdered activated carbon, respectively. The component (A) has the general formula: [R ¹ _a SiO _{(4-a) / 2} ] _n (where R ¹ is an alkyl group having 1 to 30 carbon atoms, a halogenated phenyl group, an alkenyl group, an aryl group, and A monovalent group selected from the group consisting of aralkyl groups, wherein a is a number from 1.9 to 2.7, and n is a positive number). The grease for electrical contacts according to claim 1. For 100 parts by weight of component (A),
(E) General formula:

Or general formula:

(Wherein R ² is a monovalent hydrocarbon group selected from the group consisting of an alkyl group having 1 to 18 carbon atoms and an alkenyl group, and R ³ is selected from the group consisting of an alkyl group having 3 or less carbon atoms and a phenyl group 1 3. The electrical contact according to claim 2, further comprising 1.0 to 50 parts by weight of a fatty acid ester of polyorganosiloxane, each of which represents a valent hydrocarbon group, m is a positive number. For grease.   The electrical contact grease according to any one of claims 1 to 3, wherein the thickener (B) contains silica fine powder.   The electrical contact grease according to any one of claims 1 to 4, further comprising a fluororesin fine powder which is a solid lubricant.

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