JPH0128799B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composition for protecting silver contacts of switches such as electronic devices. Traditionally, mineral oil-based greases have been used to protect contacts. However, when mineral oil-based grease is used, the contact resistance is unstable even if the plating condition of the silver surface of the contact is improved. Additionally, silver contacts made of phosphor bronze or nickel silver have had a problem of poor sulfidation resistance. Silicone grease, which has become popular in recent years, solves these problems to a considerable extent, but it is still not sufficient, so in Japanese Patent Publication No. 51-33254, polyorganosiloxane We are proposing a silicone grease that has the ability to improve sulfidation resistance and contact resistance stability by adding fatty acid-proofing esters and mercaptans, and restore the properties of contacts that have suffered from poor performance. However, even then, the improvement in malfunction over time was not satisfactory. Additionally, with the recent trend toward smaller switches, switches with lighter contact pressure are beginning to dominate the market. However, if the contact pressure is too light, the lubricity of the silicone grease decreases over time, causing a phenomenon in which the switch does not return after being pressed (this phenomenon is called galling). The present inventors applied silicone grease containing sulfide of animal and vegetable oil or olefin and mercaptan to the silver contacts of the switch.
The present invention was accomplished by discovering that the lubricity on the surface of a silver contact is significantly improved, extending the operating life of the silver contact and preventing malfunction. That is, the present invention provides (A) general formula

[Formula] (where R ¹ is an alkyl group having 1 to 30 carbon atoms,
R ² is a monovalent group selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, an alkenyl group, and a substituted or unsubstituted aryl group, and a+b is 1.9 to
2.7, where n is a positive number that satisfies the following viscosity), and the viscosity at 25℃ is
Polyorganosiloxane that is 10~100000cSt
100 parts by weight, (B) 0.01 to 50 parts by weight of thickener, (C) General formula R ³ SH (R ³ represents a saturated or unsaturated monovalent hydrocarbon group having 10 to 22 carbon atoms) ,
and general formula HSR ⁴ SH (however, R ⁴ has 3 carbon atoms)
- 0.01 to 3 parts by weight of an organothiol compound selected from the group consisting of compounds represented by (16 saturated or unsaturated divalent groups), and (D) sulfide of animal or vegetable oil or olefin 001
The present invention relates to a composition for protecting silver contacts, characterized in that the composition comprises up to 10 parts by weight. Component (A) used in the present invention has the general formula

It is a polyorganosiloxane represented by the formula: (wherein R ¹ , R ² , a, b and n are as described above). If the number of carbon atoms in R ¹ is too large, it is inconvenient to handle and the thermal stability decreases, so the number of carbon atoms is limited to 30 or less, but examples include methyl group, ethyl group, propyl group, butyl group, pentyl group, and hexyl group. , octyl group, nonyl group, decyl group, dodecyl group, etc. having 14 or less carbon atoms are preferable.
R ² is a methyl group, an ethyl group, a propyl group,
Examples include a vinyl group, a phenyl group, a chlorinated phenyl group, an iodinated phenyl group, a brominated phenyl group, and a methyl group is preferred from the viewpoint of ease of synthesis and heat resistance. The molecular structure may be linear, cyclic, or slightly branched, but a+
If the value of b is less than 1.9, the grease becomes hard and cannot be used, and if it is larger than 2.7, the viscosity range described below for the component (A) cannot be obtained. Linear oil is preferable because of its fluidity as a base oil and ease of synthesis. Siloxy units of linear molecules include R ¹ R ² SiO,
It may contain R ¹ ₂ SiO, R ² ₃ SiO _1/2 , etc., but for ease of synthesis, the general formula R ² ₃ SiO (R ¹ R ² SiO) _p (R ² SiO) _q SiR ² ₃
(p, q are integers satisfying the conditions regarding a, b, and n described above) are also preferred. The viscosity of component (A) is 25℃
is 10 to 100,000 oSt, preferably in the range of 20 to 10,000. If it is lower than 10cSt, this component will be easily separated from the grease and will be highly volatile.
Problems such as grease flowing easily occur, and if it is higher than 100,000cSt, the lubricity of the contacts will deteriorate. The thickener (B) used in the present invention is one that imparts appropriate consistency to the polyorganosiloxane (A) component, and includes fine silica powder, metal soap, carbon, graphite, talc, and organically modified bentonite. , urea resin, fluororesin, molybdenum disulfide, etc. These thickeners contain component (A)
It is necessary to select within the range of 0.01 to 50 parts by weight per 100 parts by weight. If it is less than 0.01 part by weight, it will not be possible to obtain an appropriate consistency, and when applied to the contacts, it may leak or
This is inappropriate as it may cause layer separation. Also,
If it exceeds 50 parts by weight, it is unsuitable because it causes not only poor flow but also a decrease in lubricity. Among these thickeners, fine silica powder and metal soap are particularly effective. The former significantly impairs the lubrication life when the amount is increased, but if an appropriate amount is selected, the particle size is small, from several microns to several microns, so it provides stable contact resistance even at contacts with low contact pressure. When the surface of a silver contact is chemically or physically changed due to gas contamination or surface abrasion, fine silica powder is effective in scraping off the surface. It is generally desirable to use fine silica powder in a range of 0.1 to 10 parts by weight. The latter provides the best lubricity in silicone oils among the various thickeners.
Furthermore, among metal sets, aluminum sets are superior in that they exhibit extremely stable values for contact resistance. The silica fine powder and the metal soap may be used alone, or they may be used in combination. The organothiol compound as component (C) used in the present invention is represented by the general formula R ³ SH (R ³ is as described above) or HSR ⁴ SH (R ⁴ is as described above). The organothiol compound (organomercaptan) represented by the general formula R ³ SH (R ³ is as described above) has 10 to 22 carbon atoms, preferably 18 to 22 carbon atoms. If the number of carbon atoms is less than 10, it is unsuitable because the vapor pressure is low and it easily volatizes at room temperature. Silicone greases using organomercaptans with carbon numbers of 24 or more are unsuitable because the contact resistance tends to be extremely unstable. It is. Examples of organomercaptans that meet these conditions include decylmercaptan, dodecylmercaptan, n-tetradecylmercaptan, tert-tetradecylmercaptan, hexadecylmercaptan, octamedecylcaptan, isooctadecylmercaptan, and cis-9-octadecylmercaptan. Examples include cenyl mercaptan, eicosyl mercaptan, and docosyl mercaptan. In addition, organomercaptans with a number of carbon atoms are difficult to obtain industrially.
Among the above organomercaptans, carbon number is 18~
A range of 22 is preferred. If the number of carbon atoms is 16 or less, sulfidation resistance is insufficient, and in electronic equipment such as tuners and switches that are used up to temperatures around 70°C, it will evaporate over time and will not be sufficient to provide stable sulfidation resistance. This is because the best results will not be maintained. The organothiol represented by the general formula HSR ⁴ SH (R ⁴ is as described above) has a carbon number ranging from 3 to 16. If the number of carbon atoms is less than 3, it is unsuitable because the vapor pressure is low and it easily evaporates at room temperature.
If the number of carbon atoms exceeds 16, the contact resistance tends to become extremely unstable and is therefore unsuitable. Examples of these organodithiols include 1,3-propenyldithiol, 1,4-putenyldithiol,
1,5-pentyldithiol, 1,6-hexyldithiol, 1,8-octyldithiol, 1,
Examples include 10-decyldithiol, 1,12-dodecyldithiol, 1,14-tetradecyldithiol, and the like. The amount of component (C) added is 0.01 to 3 parts by weight, preferably 0.1 to 5 parts by weight, per 100 parts by weight of component (A).
Parts by weight range. If the amount added is less than 0.01 parts by weight, the effect of the addition blend will not be recognized, and if it exceeds 3 parts by weight, the contact resistance of the grease will become extremely unstable at temperatures around 0°C, and the wear of the silver contacts will become severe, resulting in poor conductivity. It may also become defective. Component (D) of the present invention is a necessary component for extending the lubricating life of electrical contacts, which is the object of the present invention, and is obtained by reacting animal fat, vegetable fat, or olefin with sulfur. It is a sulfide. (D)
It is necessary to use the component in a range of 0.01 to 10 parts by weight per 100 parts by weight of component (A), and further 0.1 to 10 parts by weight.
It is preferable to use within the range of 3 parts by weight. If the amount added is less than 0.01 part by weight, no effect of the addition blend will be observed. In addition, if the amount exceeds 10 parts by weight, not only will the contact resistance of the electrical contact become unstable, but
It is unsuitable because it significantly impairs its ability to be used under a wide range of temperatures, which is a characteristic of silicone greases. By applying the composition consisting of components (A) to (D) to the silver contacts of a switch, the lubricity on the surface of the silver contacts and its durability are significantly improved, resulting in an extension of the operating life of the silver contacts. Malfunctions can be prevented. The present invention will be explained below with reference to Examples. In the examples, all parts are by weight. Example A polydiorganosiloxane blocked at both ends with trimethylsilyl groups as shown in Table 1 was used as the base oil. However, F-3 is a branched polyorganosiloxane.

[Table] Furthermore, as the sulfides of animal and vegetable oils and fats or olefins, those shown in Table 2 were used. In the table, S-
1 is a sulfurized fat made by reacting sulfur with animal fat consisting of myristic acid, palmitic acid, stearic acid, oleic acid and linoleic acid at high temperature;
S-2 is a sulfurized fat made by reacting sulfur with vegetable oil consisting of palmitic acid, stialic acid, oleic acid, linoleic acid and linolenic acid at high temperature.
S-3 is a sulfurized olefin made by reacting a mixture of _C12 to _C18 α-olefins with sulfur at high temperature.

[Table] Silicone greases 1 to 10 were prepared using the ingredients shown in Table 3. However, Greases 8 and 9 are comparative samples in which no animal or vegetable oil or fat or olefin sulfide is added, and Grease 10 is a comparative sample in which no organothiol compound is added. The fine silica powder is fumed silica with a specific surface area of 200 m ² /g that has been surface-treated with octamethylcyclotetrasiloxane. The numbers indicate the number of copies of each component. Using these greases, changes in contact resistance of volume contacts and changes in operating force of switch contacts with a contact load of 10 g were measured. The results are shown in Table 3. The operating force was measured for the switch parts excluding the spring.

【table】

Claims (1)

[Claims] 1 (A) General formula [Formula] (wherein R ¹ is an alkyl group having 1 to 30 carbon atoms,
R ² is a monovalent group selected from the group consisting of an alkyl group having 1 to 3 carbon atoms, an alkenyl group, and a substituted or unsubstituted aryl group, and a+b is 1.9 to
2.7, where n is a positive number that satisfies the following viscosity), and the viscosity at 25℃ is
Polyorganosiloxane that is 10~100000cSt
100 parts by weight, (B) 0.01 to 50 parts by weight of thickener, (C) General formula R ³ SH (R ³ represents a saturated or unsaturated monovalent hydrocarbon group having 10 to 22 carbon atoms) ,
and general formula HSR ⁴ SH (however, R ⁴ has 3 carbon atoms)
~16 saturated or unsaturated divalent groups) 0.01 to 3 parts by weight of an organothiol compound selected from the group consisting of compounds represented by the following: and (D) 0.01 parts by weight of an animal or vegetable oil or olefin sulfide.
A composition for protecting silver contacts, characterized in that it comprises ~10 parts by weight. 2. The composition according to claim 1, wherein the polyorganosiloxane (A) has a viscosity of 20 to 10,000 cSt at 25°C. 3. The composition according to claim 1, wherein (B) is a fine silica powder. 4. The composition according to claim 3, wherein the amount of (B) added is 0.1 to 10 parts by weight. 5. The composition according to claim 1, wherein (B) is a metal soap. 6. The composition according to claim 5, wherein (B) is an aluminum powder. 7. The composition according to claim 1, wherein (C) is an organomercaptan having 18 to 22 carbon atoms. 8. The composition according to claim 1, wherein the amount of (C) added is 0.1 to 0.5 parts by weight. 9. The composition according to claim 1, wherein the amount of (D) added is 0.1 to 3 parts by weight.