JP5374190B2 - Lubricating composition for electrical contacts - Google Patents

Abstract

The present invention provides a lubricating composition which curtails the light actuation and actuation power change at high temperatures without impairing the stabilization of contact resistance and also the sulfuration resistance at an electric contact part, and which is improved in the durability. The lubricating composition for use in electric contacts contains (A) 100 parts by weight of a polydimethylsiloxane as a base oil, (B) 1.0-20 parts by weight of a silica powder as a thickener, (C) 1.0-15 parts by weight of an additive oil, (D) 0.01-5.0 parts by weight of a fluororesin fine powder, (E) 0.01-1.0 parts by weight of an organothiol compound with a specific chemical structure and (F) 0.1-5.0 parts by weight of a specific chemical structure-containing compound of thiazoles, oxazoles, imidazoles or thiadiazoles.

Description

  TECHNICAL FIELD The present invention relates to a lubricating composition for electrical contacts, and in particular, a lubricating composition for electrical contacts used for sliding electrical contacts of mechanical parts (switches, encoders, position sensors, etc.) such as electronic devices and sliding portions adjacent thereto. About.

  Lubricating compositions used to protect sliding electrical contacts of mechanical parts such as conventional electronic devices (switches, encoders, position sensors, etc.) and sliding parts close to them are made of silicone oil or synthetic oil using silica powder or metal soap. It is a thickened lubricant. Although a lubricant using silicone oil is effective for the stability of electrical connection (Patent Document 1), there is a drawback in blocking the corrosive gas such as hydrogen sulfide, and this is compensated for. Therefore, it is common to use a sulfidation inhibitor.

  However, the addition of an anti-sulfurizing agent forms a film on the surface, which improves the lubricity, but the contact resistance becomes unstable, and even when the connection stability in the stationary state is ensured, external shock vibration and sliding Such dynamic connection stability deteriorates. Also, good connection stability means poor lubricity, and contact between contact metals by sliding becomes intense and operation becomes heavy, resulting in significant wear. Furthermore, it is known that the load of recent electrical contacts has been reduced, and even the contact using silicone oil has an adverse effect on connection stability.

  On the other hand, in the case of synthetic oils such as hydrocarbon oils, the lubricating oil film is stronger than that of silicone oil and the lubricity is good, but the contact resistance tends to be difficult to stabilize. In the past analog circuits, only the stability of the static connection has been functioning, but it cannot be used while the digital signal processing in recent years has become the mainstream of electronic circuits. In particular, with the recent trend of light and thin electrical and electronic devices, this demand is further heightened when the contact load is reduced in weight and light operation is required.

  In addition, as the usage environment of electric / electronic devices becomes wider, the level and time required for storage temperature conditions tend to increase. Further, as the size of the device becomes smaller, the temperature applied to the electronic mechanism component accompanying internal heat generation has increased. In order to improve the lubrication performance while maintaining the electrical connection, there are a method of adding an extreme pressure agent such as fluorine oil, an ester compound, and a sulfur compound and a method of adding a solid lubricant such as PTFE (polytetrafluoroethylene). It is done. However, in the case of a light-load contact, a general extreme pressure additive or the like cannot be expected to have an effect because the load pressure is not concentrated at one point. In addition, the fluidity of the lubricant itself is improved at high temperatures, and in particular, in the case of additives that are not solid or compatible, they are excluded from the contact portion together with the additive, causing direct metal-to-metal contact and initial actuation force. It is inappropriate because it becomes heavy. In addition, solid lubricants such as PTFE do not affect the temperature when used alone, but when dispersed in oil, they are excluded in the same manner as the above-mentioned extreme pressure additive. The initial action will be heavy.

JP 2005-232433 A

  These proposed methods are effective when the temperature rise of the electrical / electronic equipment is relatively small. However, in recent years, the number of devices placed at a temperature close to 100 ° C. has increased, and the device has been left unattended for more than 100 hours, so that the sliding portion has been exposed to stricter conditions than before. As a result, changes in quality such as electrical contact and other contact lubricants are lost and oxidized, and the operating force increases rapidly, resulting in a fatal state that is inoperable (referred to as “galling”). There is also.

  At a light load, although there is a difference between these states, galling occurs when the temperature exceeds a certain level. In order to improve this, a method of adding an additive constituting a strong lubricating film and a method of using a large amount of the additive are proposed, but these methods impair electrical connection and cause a contact failure.

  There is a need for a lubricating composition that can ensure the stability of electrical connection in a stationary state and a sliding state at a light load contact of about a few tens of grams, and can stabilize the operating force even when left for a long time in a high temperature state. ing.

  The present invention has been made in view of the above points, and is an electric contact that is improved in durability while reducing light operation and change in operating force at high temperature without impairing the stabilization of contact resistance and sulfidation resistance of the electric contact portion. An object of the present invention is to provide a lubricating composition.

The lubricating composition for electrical contacts of the present invention comprises (A) 100 parts by weight of polydimethylsiloxane as a base oil, (B) 3 to 5 parts by weight of silica powder as a thickener, and (C) an additive oil. 0 part by weight to 15 parts by weight, (D) 0.1 part by weight to 1.0 part by weight of fluororesin fine powder, and (E) the general formula R ¹ SH (R ¹ is a carbon number of 10 to 20 carbon atoms) A saturated or unsaturated monovalent hydrocarbon group) and a general formula HSR ² SH (R ² represents a saturated or unsaturated divalent hydrocarbon group having 3 to 16 carbon atoms). And 0.05 part by weight to 1.0 part by weight of an organothiol compound selected from the group consisting of the following compounds: (F) general formula —N═C (X) —S—R ³ (wherein R ³ is the number of carbon atoms) A saturated or unsaturated monovalent hydrocarbon group having 6 to 16 carbon atoms, wherein X is one of the elements C, S or N Indicates that it is bound with.) And the general formula -N = C (X) -S- S-R 4 ( wherein, ^{R 4} is a monovalent saturated or unsaturated 16 carbon 6 atoms carbon atoms Thiazoles or oxazoles selected from the group consisting of compounds having a partial structure represented by the following: X represents a hydrocarbon group, and X represents that one of the elements of C, S or N is bonded to carbon. Or 0.1 to 5.0 parts by weight of an imidazole or thiadiazole compound, and the polydimethylsiloxane is a kind of polydimethylsiloxane having a viscosity at 25.0 ° C. of 500 cSt to 10,000 cSt. or a more mixed oil of the a silica powder is fumed silica, a specific surface area of ^{50m 2} / ^g~300m 2 / g, the additive oil is a fluorine-based oil, 98.9 Viscosity at is characterized in that it is a 1CSt～50cSt.

  According to this configuration, when used in sliding electrical contacts of mechanical parts such as electronic devices and sliding portions adjacent thereto, an oil film generated by the base oil is added by an additive oil having compatibility with the base oil. Since it is easy to break, the contact resistance of the electrical contact portion can be stabilized, lubrication performance can be exhibited by the fluororesin fine powder, and sulfidation resistance can be exhibited by the organothiol compound. Further, by adding thiazoles, oxazoles, imidazoles, or thiadiazole compounds, it is possible to reduce light operation and change in operating force even at high temperatures and improve durability. Furthermore, by adjusting the content of each component, long-term operating durability can be significantly improved without impairing contact resistance stabilization or sulfidation resistance.

In the lubricating composition for electrical contacts of the present invention, it is preferable that a polyorganosilicone oil and / or an aliphatic hydrocarbon oil is mixed with the fluorine oil .

  In the lubricating composition for electrical contacts of the present invention, the organothiol compound is preferably an organomercaptan having 12 to 20 carbon atoms.

In the lubricating composition for electrical contacts of the present invention, the thiazoles, oxazoles, imidazoles or thiadiazole compounds are represented by the general formula —N═C (S) —S—S—R ⁴ (wherein R ⁴ represents the number of carbon atoms). It is preferably a thiazole or thiadiazole compound selected from the group consisting of compounds having a partial structure represented by 6 to 16 carbon atoms, a saturated or unsaturated monovalent hydrocarbon group.

  In the lubricating composition for electrical contacts of the present invention, the thiazoles, oxazoles, imidazoles or thiadiazole compounds are preferably thiadiazole compounds having 6 to 12 carbon atoms.

  The electrolubricating composition of the present invention is a light load having a contact force of several gf when used for sliding electrical contacts of mechanical parts such as electronic devices (switches, encoders, position sensors, etc.) and sliding parts adjacent thereto. The contact resistance of the electrical contacts is stable and the resistance to sulfidation is not impaired, and light operation and change in operating force are reduced even at high temperatures, and the durability is remarkably improved and extremely reliable. High electrical contact can be provided.

Embodiments of the present invention will be described below.
The lubricating composition for electrical contacts of the present invention comprises (A) 100 parts by weight of polydimethylsiloxane as a base oil, (B) 3 to 5 parts by weight of silica powder as a thickener, and (C) an additive oil. 0 part by weight to 15 parts by weight, (D) 0.1 part by weight to 1.0 part by weight of fluororesin fine powder, and (E) the general formula R ¹ SH (R ¹ is a carbon number of 10 to 20 carbon atoms) A saturated or unsaturated monovalent hydrocarbon group) and a general formula HSR ² SH (R ² represents a saturated or unsaturated divalent hydrocarbon group having 3 to 16 carbon atoms). And 0.05 part by weight to 1.0 part by weight of an organothiol compound selected from the group consisting of the following compounds: (F) general formula —N═C (X) —S—R ³ (wherein R ³ is the number of carbon atoms) A saturated or unsaturated monovalent hydrocarbon group having 6 to 16 carbon atoms, wherein X is one of the elements C, S or N Indicates that it is bound with.) And the general formula -N = C (X) -S- S-R 4 ( wherein, ^{R 4} is a monovalent saturated or unsaturated 16 carbon 6 atoms carbon atoms Thiazoles or oxazoles selected from the group consisting of compounds having a partial structure represented by the following: X represents a hydrocarbon group, and X represents that one of the elements of C, S or N is bonded to carbon. Or 0.1 to 5.0 parts by weight of an imidazole or thiadiazole compound, and the polydimethylsiloxane is a kind of polydimethylsiloxane having a viscosity at 25.0 ° C. of 500 cSt to 10,000 cSt. or a more mixed oil of the a silica powder is fumed silica, a specific surface area of ^{50m 2} / ^g~300m 2 / g, the additive oil is a fluorine-based oil, 98.9 Viscosity at is characterized in that it is a 1CSt～50cSt.

In the lubricating composition for electrical contacts of the present invention, polydimethylsiloxane commonly referred to as silicone oil is used as the base oil (A) as the main component. Polydimethylsiloxane is, the fluidity of the lubricating composition, the lubricating effect, in consideration of viscosity resistance, and having a viscosity of 500cSt~10,000cSt at temperature 25 ° C.. Such polydimethylsiloxane may be one kind or a mixture of plural kinds of different viscosities. The molecular shape of polydimethylsiloxane may be linear or branched.

In the lubricating composition for electrical contacts of the present invention, silica powder is used as the thickener (B) that imparts an appropriate consistency to the base oil (A). This thickener (B) is in the range of 3 to 5 parts by weight with respect to 100 parts by weight of the base oil (A) component in consideration of imparting an appropriate consistency, ease of application, lubricity and the like. Used in. When silica powder is blended at an appropriate blending amount, the particle size is as small as several nanometers to several micrometers, so it is effective to scrape and remove the contaminated film and oxide film formed on the surface without impairing the connection of electrical contacts. It is.

Silica powder has a specific surface area of fumed silica of ^{50m 2} / ^g~300m 2 / g. The famed silica that has been surface-treated with organosilane, polyorganosiloxane, organosilazane, or the like may be used .

  The lubricating composition for electrical contacts of the present invention contains an additive oil (C) having a different compatibility with polydimethylsiloxane. In the lubricating composition for electrical contacts, the additive oil (C) has a function of assisting lubrication performance and also makes the oil film produced by the base oil (A) easily breakable. For this reason, “additive oil having different compatibility” means that the base oil (A) has a relatively low affinity with the polydimethylsiloxane, that is, the composition formula is different from that of the base oil (A), or is added to the base oil (A). The difference in the solubility parameter (SP value) of the oil is in the range of 0.3 to 1.5 in absolute value and the viscosity is 500 cSt (25.0 degrees) or more with respect to the average viscosity of (A). Means added oil. This additive oil (C) is in the range of 1.0 to 15 parts by weight with respect to 100 parts by weight of the base oil (A) component in consideration of lubrication performance and easy tearing of the oil film created by the base oil. Use.

Examples of the additive oil (C) include polyorganosilicone oil, aliphatic hydrocarbon oil, and fluorine oil. The polyorganosilicone oil is represented by an average composition formula R ³ _a SiO _{(4-a) / 2} . This polyorganosilicone oil may be one kind or a mixed oil of plural kinds. In the average composition formula, as the organic group R ³ bonded to the silicon atom, a substituted or daily substituted monovalent hydrocarbon group, for example, a methyl group, an ethyl group, a propyl group, a butyl group, an amyl group, a hexyl group, an octyl group Alkyl groups having 1 to 30 carbon atoms such as a group, dodecyl group, hexadecyl group, octadecyl group; aryl groups such as phenyl groups; aralkyl groups such as β-phenylethyl groups, chloromethyl groups, trifluoropropyl groups, etc. And a substituted monovalent hydrocarbon group. These R ³ may be the same or two or more different. Moreover, in said average composition formula, a is a number of 1.9-2.7, and shows the average value per silicon atom in a molecule | numerator. Of these organic groups, 50% or more is preferably a methyl group in view of ease of synthesis and heat resistance.

  These polyorganosilicone oils desirably have a viscosity of 10 cSt to 500 cSt at a temperature of 25 ° C. in consideration of volatility, lubrication performance, electrical connection stability (contact resistance), viscosity resistance, and the like. This viscosity is desirably lower than the viscosity of the base oil (A). Such polyorganosilicone oil may be one kind or a plurality of kinds of mixed oils. In the case of a plurality of types of mixed oils, a mixture of oils having different viscosities may be used. The molecular shape of the polyorganosilicone oil may be linear or branched. The polyorganosilicone oil is preferably an alkyl-modified silicone oil from the viewpoint of affinity with petroleum-based additives.

  Examples of the aliphatic hydrocarbon oil include liquid paraffin, poly α-olefin oligomer, olefin copolymer, and mineral oil. This aliphatic hydrocarbon oil preferably has a viscosity at 98.9 ° C. of 1 cSt to 20 cSt in consideration of lubrication performance, electrical connection stability (contact resistance), viscous resistance, and the like. This viscosity is desirably lower than the viscosity of the base oil.

Examples of the fluorine oil include perfluoroalkane, polytrifluorinated ethylene, and perfluoropolyether. In particular, perfluoropolyether has a low affinity with other oils but is relatively easy to mix and is excellent in the stability of the properties of the composition. The fluorine oil, fluidity, electrical connection stability (contact resistance) and the like into consideration, and a viscosity at 98.9 ° C. is 1CSt～50cSt. This viscosity is desirably lower than the viscosity of the base oil (A).

  The additive oil (C) is a fluorine oil alone or a mixture of a polyorganosilicone oil and / or an aliphatic hydrocarbon oil in the blending range.

The lubricating composition for electrical contacts of the present invention contains a fluororesin fine powder (D). This fluororesin fine powder (D) is effective in lubrication performance, particularly lubricity in a temperature range exceeding 60 degrees, and is necessary for stabilization of lubrication performance. The fluororesin fine powder (D) is used in the range of 0.1 parts by weight to 1.0 parts by weight with respect to 100 parts by weight of the base oil component, considering that it does not become an obstacle as a foreign matter to the electrical contacts. The average particle size of the fluororesin fine powder (D) is preferably 0.05 μm to 20 μm.

The lubricating composition for electrical contacts of the present invention has a general formula R ¹ SH (R ¹ represents a saturated or unsaturated monovalent hydrocarbon group having 10 to 20 carbon atoms) and a general formula HSR ² SH (R ² contains an organothiol compound (E) selected from the group consisting of compounds represented by (C 3 -C 16 saturated or unsaturated divalent hydrocarbon group). This organothiol compound (E) is a component that exhibits sulfidation resistance. In consideration of sulfidation resistance, stability of contact resistance value, etc., 0.05 part by weight to 100 parts by weight of the base oil component Used in the range of 1.0 part by weight .

Among the organothiol compounds (E), the organothiol compound (organomercaptan) represented by the general formula R ¹ SH is C10-C20, preferably in consideration of vapor pressure, stability of contact resistance, etc. It is preferable that it is the range of C14-C18. Examples of such organomercaptans include decyl mercaptan, dodecyl mercaptan, tetradecyl mercaptan, hexadecyl mercaptan, octadecyl mercaptan, lauryl mercaptan, cetyl mercaptan, stearyl mercaptan, β-naphthalene thiol and the like.

Among the organothiol compounds (E), the organodithiol compound represented by the general formula HSR ² SH is in the range of 3 to 16 carbons in consideration of vapor pressure, stability of contact resistance, etc. Is preferred. Examples of such organodithiols include 1,3-trimethylenedithiol, 1,4-tetramethylenedithiol, 1,5-pentamethylenedithiol, 1,6-hexamethylenedithiol, 1,8-octamethylenedithiol, , 10-decamethylenedithiol and the like.

The lubricating composition for electrical contacts of the present invention has a —N═C (X) —S—R ³ (wherein R ³ represents a saturated or unsaturated monovalent hydrocarbon group having 6 to 16 carbon atoms). X represents that one of the elements of C or S or N is bonded.) And —N═C (X) —S—S—R ⁴ (wherein R ⁴ has 6 carbon atoms) A compound having a partial structure represented by a saturated or unsaturated monovalent hydrocarbon group having 16 carbon atoms, wherein X represents that one of C, S, or N is bonded. A thiazole, oxazole, imidazole, or thiadiazole compound (F) (hereinafter simply referred to as compound (F)) selected from the group consisting of:

  The compound (F) is usually used as a corrosion inhibitor in the range of 0.003 to 0.03 parts by weight with respect to 100 parts by weight of the base oil (A) component. The present inventors have discovered that the compound (F) exhibits a special performance with respect to silver contacts by using the compound (F) in a predetermined ratio with respect to 100 parts by weight of the base oil component. In the lubricating composition for electrical contacts of the present invention, the lubricating performance at high temperature is obtained by using 0.1 part by weight to 5.0 parts by weight of the compound (F) with respect to 100 parts by weight of the base oil (A) component. Is stabilized and the stability of the contact resistance can be improved.

Among these compounds (F), from the viewpoint of lubrication performance and stability of contact resistance, the general formula —N═C (S) —S—S—R ⁴ (wherein R ⁴ has 6 to 6 carbon atoms) A thiazole or thiadiazole compound selected from the group consisting of a partial structure represented by the following formula: 16 saturated or unsaturated monovalent hydrocarbon groups. Among these thiazoles or thiadiazole compounds, thiadiazole having 6 to 12 carbon atoms is particularly preferable.

In the lubricating composition for electrical contacts of the present invention, by using the organothiol compound (E) and the compound (F) in combination, good lubricating performance and stable contact resistance can be obtained over a wide range from low temperature to high temperature. Can do. In the organothiol compound (E) and the compound (F), each sulfur atom is coordinated to the surface of the metal, and the general formula —R ⁵ S ^— M ⁺ (wherein R ⁵ is an arbitrary substituent, M Represents a metal atom). Thus, by forming mercaptide, a monomolecular film of the organothiol compound (E) and the compound (F) of about several angstroms is formed on the metal surface. By forming this monomolecular film, good lubrication performance and stability of contact resistance can be expressed.

  Moreover, in the lubricating composition for electrical contacts of the present invention, by utilizing the difference in coordination of sulfur atoms between the organothiol compound (E) and the compound (F), good lubricating performance over a wide range of temperatures and Expresses the stability of contact resistance. The sulfur atom of the organothiol compound (E) coordinates suitably on the metal surface at a low temperature (10 ° C. to 50 ° C.). On the other hand, the sulfur atom of the compound (F) is suitably coordinated to the metal surface at a high temperature (60 ° C to 100 ° C). Therefore, at low temperatures, the organothiol compound (E) forms a monomolecular film on the metal surface, and at high temperatures, the compound (F) forms a monomolecular film on the metal surface. By blending the compound (F) at a predetermined ratio, good lubrication performance and stability of contact resistance can be obtained over a wide temperature range.

  In addition, the sulfur atom of the compound (F) has a higher coordination property to the metal surface than the organothiol compound (E), and when used alone, there is a concern about sulfurization of the metal surface. In the resin composition for electrical contacts of the present invention, a component of the organothiol compound (E) having a different coordination property from the compound (F) to the metal surface of the sulfur atom is blended at a predetermined ratio. Thus, the compound (F) is used by adjusting the coordination of the organothiol compound (E) to the metal of the sulfur atom and the coordination of the sulfur atom of the compound (F) to the metal atom. However, good lubrication performance and stability of contact resistance can be obtained without flowing metal. For example, by increasing the organothiol compound (E) with respect to the compound (F), coordination of the organothiol compound (E) to the metal surface is promoted, and sulfidation of the metal surface by the compound (F) can be suppressed. In addition, by increasing the number of compounds (F) having high coordination properties to the metal surface at high temperatures relative to the organothiol compound (E), a monomolecular film on the metal surface can be formed well even at high temperatures, and lubrication performance and contact Resistance stability can be obtained.

  Furthermore, in the lubricating composition for electrical contacts of the present invention, the organothiol compound (E) and the compound (F) may each use a single component, or a mixture of a plurality of components. For example, any organothiol compound (E) or compound (F) is selected, and other organothiol compound (E) or compound (F) is selected so as to complement the coordination property of the sulfur atom to the metal surface. By selecting and mixing the compound (F) or the organothiol compound (E), lubrication performance and contact resistance stability can be obtained over a wide temperature range and various metal materials.

  The blending ratio of the organothiol compound (E) and the compound (F) is 1% by weight to 2% by weight with respect to the total amount of the lubricating composition for electrical contacts from the viewpoint of lubrication performance and contact resistance stability. preferable.

  When the lubricating composition for electrical contacts of the present invention having the above composition is used for sliding electrical contacts of mechanical parts such as electronic devices (switches, encoders, position sensors, etc.) and sliding parts close to them, There is an effect of remarkably improving durability while reducing light operation and change in operating force from low to high temperatures without impairing the stabilization of contact resistance and sulfidation resistance of the electrical contact portion.

Next, reference examples made to clarify the effects of the present invention will be described. The present invention is not limited to the following reference examples . In the reference examples , “parts” means “parts by weight”, and the viscosity indicates a value at 25 ° C. unless otherwise specified. Moreover, since the viscosity is not finally adjusted but the addition amount is maintained, the viscosity of the finished lubricating composition varies depending on each reference example .

( Reference Example 1)
To 100 parts by weight of a polydimethyl silicone oil having a viscosity of 5,000 cSt as a base oil, 5 parts by weight of dimethyl silicone oil having a low viscosity (50 cSt) was added as an additive oil having a different compatibility with this. The oil was first thickened with 3 parts by weight of silica powder, and as additives, 0.5 parts by weight of fluororesin fine powder, 0.05 parts by weight of stearyl mercaptan and 0.10 parts by weight of thiadiazole having 10 carbon atoms were added. Finally, it was kneaded with a three-roll mill until it became grease-like. There was thus obtained electrical contacts lubricating composition of Reference Example 1 (Reference Example 1). The weight ratio of silica powder / added oil was 0.6. The weight ratio of each component is shown in Table 1 below.

About the lubricating composition for electrical contacts of Reference Example 1, the operating life, high-temperature operating force, high-temperature contact resistance, and sulfide characteristics were examined. The results are shown in Table 2 below. The service life is the value of contact resistance value, noise and operating force at the time of 10,000 times and 100,000 times of operation. Judged. For operating life, the switch was moved with a dedicated test device operating approximately 30 times per minute. The contact resistance was measured using a YHP milliohm meter 4338B. The bounce state was measured using an oscilloscope at 5 V and 500 μA for noise.

The operating force evaluation is as follows with respect to the initial reference value.
Standard value <+ 10%: ◎
Standard value <+ 30%: ○
Reference value <+ 50%: △
Reference value <+ 100%: ×
Reference value> + 100%: XX

Evaluation of contact resistance value and noise is as follows.
30 mΩ or less and no noise: ◎
50 mΩ or less and no noise: ○
100mΩ or less and low noise: △
100 mΩ or more and low noise: ×
100mΩ or more and large noise: XX

  The lubricating composition for electrical contacts was also examined for high temperature storage characteristics. In other words, thinly apply the lubricant composition for electrical contacts to the contacts of a single circuit push switch, and determine the contact resistance value, noise, and operating force values after leaving it at 85 ° C for 250 hours and 500 hours in a general-purpose thermostat. did.

The operating force evaluation is as follows with respect to the initial reference value.
Standard value <+ 10%: ◎
Standard value <+ 30%: ○
Reference value <+ 50%: △
Reference value <+ 100%: ×
Reference value> + 100%: XX

Evaluation of contact resistance value and noise is as follows.
30 mΩ or less and no noise: ◎
50 mΩ or less and no noise: ○
100mΩ or less and low noise: △
100 mΩ or more and low noise: ×
100mΩ or more and large noise: XX

Sulfurization characteristics are as follows. Lubricating composition for electrical contacts is thinly applied to the contacts of a four-circuit push switch and tested using a sulfidation tester manufactured by Yamazaki Seiki Co., Ltd., hydrogen sulfide 1 ppm, 40 ° C., relative humidity 70% RH to relative Judgment was made from the contact resistance value after leaving in an environment of humidity 75% RH for 240 hours and the discolored state of the contact part. The degree of discoloration is a visual judgment.
Less than 50mΩ and slight discoloration: ◎
Less than 100mΩ and small discoloration: ○
Less than 200mΩ and discoloring: △
200mΩ or more and large discoloration: ×

( Reference Example 2 to Reference Example 8, Comparative Example 1 to Comparative Example 9)
The components shown in Table 1 below were blended in predetermined amounts, finished kneaded until greasy with three rolls Reference Example 2 to Reference Example 8 A lubricating composition for electrical contacts of Comparative Example 1 to Comparative Example 7 Got. Reference example 2 Reference Example 8, the electrical contacts lubricating composition of Comparative Example 1 to Comparative Example 7, the initial contact resistance, initial actuation force, operating life, were examined sulfide characteristics. The results are also shown in Table 2 below. Of the reference examples 2 to 8, only the reference example 7 satisfies all the requirements of the present invention and can be called an example.

  As can be seen from Table 2, the lubricating composition for electrical contacts of Comparative Example 1 had poor high temperature operating force and contact resistance. This is considered because the oil film produced | generated with the base oil (A) became difficult to cut | disconnect because there is little quantity of the addition oil (C) with which compatibility with a base oil (A) is different. The lubricating composition for electrical contacts of Comparative Example 2 had poor high temperature operating force and contact resistance. This is presumably because of the large amount of fluororesin fine powder, which became an obstacle as a foreign object in the electrical contact. The lubricating composition for electrical contacts of Comparative Example 3 had poor contact resistance and operating force. This is presumably because the contact resistance value became unstable due to the large amount of organothiol compound added. The lubricating composition for electrical contacts of Comparative Example 4 did not function as a lubricating composition. This is presumably because the base oil and the additive oil were separated because the amount of the additive oil added to the thickener was large. The lubricating composition for electrical contacts of Comparative Example 5 had poor operating life and high temperature operating force. This is presumably because the oil film produced by the base oil was not efficiently broken because the amount of additive oil added to the thickener was small. The lubricating composition for electrical contacts of Comparative Example 6 had a poor high temperature operating force. This is presumably because the lubricity at high temperature did not develop because there was no component of compound (F). The lubricating composition for electrical contacts of Comparative Example 7 had poor contact resistance. This is presumably because mercaptides were formed on the metal surface because of the large amount of the compound (F).

  As described above, according to the lubricating composition for electrical contacts of the present invention, by using the additive oil (C) having different compatibility with the base oil (A) and various additives, a wide range from low temperature to high temperature can be obtained. A lubricating composition for electrical contacts that has good lubricating performance in a range and can be used for a long time is obtained.

  The embodiment disclosed this time is illustrative in all respects and is not limited to this embodiment. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

The lubricating composition for electrical contacts of the present invention is effective for sliding electrical contacts of mechanical parts (switches, encoders, position sensors, etc.) such as electronic devices and sliding portions adjacent thereto.

Claims (5)

(A) 100 parts by weight of polydimethylsiloxane as a base oil;
(B) 3 to 5 parts by weight of silica powder as a thickener;
(C) 1.0 to 15 parts by weight of additive oil;
(D) 0.1 to 1.0 part by weight of fluororesin fine powder,
(E) General formula R ¹ SH (R ¹ represents a saturated or unsaturated monovalent hydrocarbon group having 10 to 20 carbon atoms) and general formula HSR ² SH (R ² represents 3 to carbon atoms) and organo thiol compound 0.05 part by weight to 1.0 parts by weight chosen from the group consisting of compounds represented by.) showing a divalent hydrocarbon group having 16 saturated or unsaturated,
(F) General formula —N═C (X) —S—R ³ (wherein R ³ represents a saturated or unsaturated monovalent hydrocarbon group having 6 to 16 carbon atoms, and X represents C or And one of the elements of S or N is bonded to carbon.) And the general formula —N═C (X) —S—S—R ⁴ (wherein R ⁴ has 6 to carbon atoms) A compound having a partial structure represented by the following formula: 16 represents a saturated or unsaturated monovalent hydrocarbon group, and X represents that one of the elements of C, S or N is bonded to carbon. 0.1 to 5.0 parts by weight of a thiazole or oxazole or imidazole or thiadiazole compound selected from the group consisting of:
Contain,
The polydimethylsiloxane is one or more mixed oils of polydimethylsiloxane having a viscosity at 25.0 ° C. of 500 cSt to 10,000 cSt,
The silica powder is fumed silica, the specific surface area of ^{50m 2} / ^g~300m 2 / g,
The lubricating oil composition for electrical contacts, wherein the additive oil is a fluorinated oil and has a viscosity at 98.9 ° C. of 1 cSt to 50 cSt .   The lubricating composition for electrical contacts according to claim 1, wherein a polyorganosilicone oil and / or an aliphatic hydrocarbon oil is mixed with the fluorine oil. The lubricating composition for electrical contacts according to claim 1 or 2, wherein the organothiol compound is an organomercaptan having 12 to 20 carbon atoms. The thiazoles, oxazoles, imidazoles or thiadiazole compounds are represented by the general formula —N═C (S) —S—S—R ⁴ (wherein R ^{4 is} a saturated or unsaturated 1 having 6 to 16 carbon atoms). 4. The electrical contact according to claim 1 , wherein the compound is a thiazole or thiadiazole compound selected from the group consisting of compounds having a partial structure represented by: Lubricating composition. The lubricating composition for electrical contacts according to claim 4, wherein the thiazole, oxazole, imidazole or thiadiazole compound is a thiadiazole compound having 6 to 12 carbon atoms.