JPH0376359B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention provides lubricity to a rotating shaft portion such as a rotary variable resistor (volume) or dial of an electronic component switch, various audio devices, etc. to smooth its rotation, and reduces rotational resistance in a bearing. The present invention relates to a silicone grease that appropriately utilizes (torque) to give a luxurious feel to the hands of those who perform rotational operations. [Technical background of the invention and its problems] Greases conventionally used for the purpose of imparting luxury and lubricity to the rotating shafts of rotating volumes such as electronic parts and audio equipment include, for example, polyisobutene and thickeners. Those consisting of polyisobutene, mineral oil and a thickening agent are generally known. However, these greases have the disadvantage that if they are left in a high temperature area of 100℃ or higher for a long time, the viscosity of the polyisobutene decreases rapidly and it flows out of the applied area, or the polyisobutene begins to decompose and the grease itself becomes hard. . On the other hand, it solidifies in a low temperature region around 0° C., making it difficult to operate the volume or, in extreme cases, making it impossible to rotate it. Various proposals have been made in the past as attempts to improve this type of drawback, for example,
66552 and JP-A-53-43171 disclose inventions relating to silicone greases having appropriate adhesiveness. In other words, the above-mentioned Japanese Patent Application Publication No. 1973
Publication No. 66552 discloses a silicone grease comprising a polydiorganosiloxane and an organosiloxane composition comprising a polyorganosiloxane comprising R ₃ SiO _1/2 units, R ₂ SiO units and SiO ₂ units, and a thickener. JP-A-53-43171 discloses polydiorganosiloxane and
A silicone grease comprising a polyorganosiloxane composition comprising R ₃ SiO _1/2 units, RSiO _3/2 units and SiO ₂ units and a thickener is disclosed (wherein R is an alkyl group, an alkenyl group, an aryl group). (a group selected from the group). However, these silicone greases
When the rotating volume is operated for a long time, the torque value decreases, and the rotating shaft eventually becomes damaged and stops moving (so-called seizure). The inventor of the present invention conducted research to eliminate such conventional drawbacks, and found that the cause of the decrease in torque value described above was due to the molecular backbone chain of linear polyorganosiloxane, which was conventionally used as a base oil for silicone grease. It was confirmed that this was caused by the amputation. In other words, in order to increase the torque value of silicone grease, it is necessary to increase the viscosity of the base oil, which is silicone oil.For this reason, linear polyorganosiloxane has traditionally been used as the base oil, but it is necessary to increase the rotational volume. When operated for a long time, the chains of the molecular skeleton that form this linear polyorganosiloxane are cut,
The adsorption force of the rotating volume to the rotating shaft is reduced, and the torque value of the rotating volume is reduced,
Otherwise, it was causing burn-in. [Objective of the Invention] The present invention has been made based on the above findings, and is a relatively new base oil that uses a polyorganosiloxane having repeating units of a specific structure in the molecule as a base oil instead of a linear polyorganosiloxane. It is an object of the present invention to provide a silicone grease that has good tackiness in a range from a low temperature region to a high temperature region, has little change in torque value when used for a long time, and has a long operating life. [Summary of the Invention] That is, the silicone grease of the present invention has the following: (A) Average compositional formula (R ¹ SiO _3/2 ) _l (R ² ₂ SiO) _n (R ³ ₃
SiO _1/2 ) _o (wherein R ¹ , R ² and R ³ are each a monovalent group selected from the group consisting of an alkyl group having 1 to 30 carbon atoms, a substituted and unsubstituted aryl group, is a number from 1 to 4, m is a number selected to achieve the required viscosity range, and n is a number from 1 to 6), and the viscosity at 25°C is 100 to 500,000 cSt. It consists of 100 parts by weight of organosiloxane, (B) R ⁴ ₃ SiO _1/2 units and SiO ₂ units, and has ⁵ OR groups bonded to the Si atom (however, R ⁴ is a monovalent group that is the same or different from each other). hydrocarbon group,
R ⁵ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms), R ⁴ ₃ SiO _1/2 per mol of SiO ₂ unit
Benzene-soluble polyorganosiloxane (resin) 1-250 with a unit mole number of 0.4-2.0 moles
parts by weight, and (C) 2 to 180 parts by weight of a thickener. The reason why the components of the silicone grease and their blending amounts are limited as described above in the present invention is as follows. That is, if the number of carbon atoms in R ¹ , R ² , and R ³ of the branched polyorganosiloxane of component (A) exceeds 30, it is not preferable because handling becomes inconvenient and the thermal stability also decreases. R ¹ may be the same or different, such as methyl, ethyl, propyl, butyl,
Examples include pentyl value, hexyl group, phenyl group, and chlorinated phenyl group. The same applies to R ² and R ³ . l is a number from 1 to 4. When l is 0, the polyorganosiloxane obtained becomes linear,
If it exceeds 4, the polyorganosiloxane will be three-dimensionally crosslinked and gelled, which is not preferable.
In addition, m is a number selected to give the polyorganosiloxane obtained the necessary viscosity (100 to 500000 cSt at 25°C), and varies depending on the number of l, but in order to make the viscosity 100 cSt or more, m is 80
It is preferable that it is above. Furthermore, n is 1 because the obtained polyorganosiloxane does not gel.
Although it needs to be above 6, it is not preferable because a large amount of linear polyorganosiloxane will be contained in the polyorganosiloxane. Furthermore, if the viscosity of the branched polyorganosiloxane (A) is less than 100 cSt at 25° C., the volatility of the polyorganosiloxane becomes large and the obtained silicone composition becomes easy to flow, which is not preferable. On the other hand, those whose viscosity exceeds 500,000 cSt are difficult to synthesize and workability decreases, which is not preferable. These branched polyorganosiloxanes (A) have a three-dimensional molecular structure compared to linear polyorganosiloxanes, so they have higher viscosity and adhesive strength even with the same molecular weight. Therefore, silicone grease containing this has improved adhesive strength and is maintained for a long period of time compared to conventional silicone grease. The benzene-soluble polyorganosiloxane (resin) as the component (B) is a component for further increasing the tackiness of the branched polyorganosiloxane as the component (A) to impart appropriate tackiness to the resulting grease. Here, R ⁴ of the above polyorganosiloxane may be the same or different from each other, and examples thereof include a methyl group, an ethyl group, a propyl group, a vinyl group, and a phenyl group. In addition,
Examples of the OR ⁵ group include a hydroxyl group and an alkoxy group such as a methoxy group, an ethoxy group, and a propoxy group, and they may be the same or different.
The amount of R ⁴ ₃ SiO _1/2 units per mole of SiO ₂ units is 0.4
If it is less than 2.0 moles, it will not be possible to impart sufficient tackiness to the resulting grease, and if it exceeds 2.0 moles, the compatibility with component (A) will deteriorate, so both are not preferred. The amount of benzene-soluble polyorganosiloxane (resin) (B) added is 1 part by weight per 100 parts by weight of component (A).
If it is less than 250 parts by weight, a composition with sufficient tackiness cannot be obtained, and if it exceeds 250 parts by weight, the resulting composition will solidify and become unusable as a grease, so neither is preferable. The thickener component (C) used in the present invention is one that imparts appropriate consistency to components (A) and (B), and includes fine silica powder, metal soap, carbon, graphite,
Examples include fine powders of fluororesins such as talc, organically modified bentonite, urea resin, molybdenum disulfide, ethylene tetrafluoride resin, and propylene hexafluoride resin. Among these, fine silica powder, lithium soap, and fine fluororesin powder are preferred from the viewpoint of ease of availability and workability. Furthermore, if the amount of component (C) is less than 2 parts by weight per 100 parts by weight of component (A), an appropriate consistency cannot be obtained and the resulting grease becomes fluid, and when applied to the rotating shaft of a rotating volume, This is inappropriate as it may cause outflow, layer separation, etc. Moreover, if it exceeds 180 parts by weight, the consistency becomes too large, making it difficult to apply to the rotating shaft, reducing the lubricity, and undesirably polishing the rotating shaft more than necessary, which may cause seizure. The silicone grease of the present invention can be produced by mixing the above-mentioned three components by conventional means, or by stirring and mixing them under heating at a predetermined temperature, and after cooling, kneading them uniformly using three rolls such as paint rolls. It can be easily obtained by If necessary, various additives such as antioxidants such as amine compounds and selenium compounds, and extreme pressure additives such as halogen compounds and phosphoric acid compounds may be added to the extent that the effects of the present invention are not impaired. You may. [Effects of the Invention] As explained above, the silicone grease of the present invention has extremely small changes in consistency and torque value over a wide temperature range, has a long operating life, and is suitable for electrical products such as stereos, radios, televisions, etc. It can be widely used in various rotating volumes of other acoustic communication devices. [Embodiments of the Invention] Next, embodiments of the present invention will be described. The branched polyorganosiloxane used in the present invention was synthesized under the following conditions. Synthesis Example 1 To 100 parts by weight of octamethylcyclotetrasiloxane, the average composition formula (CH ₃ SiO _3/2 ) ((CH ₃ ) ₂ SiO) ₄
1 part by weight of organosiloxane represented by ((CH ₃ ) ₃ SiO _1/2 ) ₂ was blended and subjected to alkaline polymerization at 25°C.
A branched polyorganosiloxane (A-1) having a viscosity of 65,000 sSt was obtained. Synthesis Example 2 To 100 parts by weight of octamethylcyclotetrasiloxane, the average composition formula

[Formula] 1 part by weight of organosiloxane represented by ((CH ₃ ) ₂ SiO) ₆ ((CH ₃ ) ₃ SiO _1/2 ) ₃ and (CH ₃ ) ₃ SiO
0.2 parts by weight of an organosiloxane represented by ((CH ₃ ) ₂ SiO) ₂ Si(CH ₃ ) ₃ was blended and polymerized under an acid catalyst to form a branched polyorganosiloxane (A-2) with a viscosity of 4400 cSt at 25°C. ) was obtained. Synthesis Example 3 To 100 parts by weight of octamethylcyclotetrasiloxane, the average compositional formula (CH ₃ SiO _3/2 ) ₂ ((CH ₃ ) ₂ SiO) ₆
1 part by weight of organosiloxane represented by ((CH ₃ ) ₃ SiO _1/2 ) ₃ was blended and subjected to alkaline polymerization at 25°C.
A branched polyorganosiloxane (A-3) having a viscosity of 100,000 cSt was obtained. Synthesis Example 4 100 parts by weight of octamethylcyclotetrasiloxane was added with the average composition formula (CH ₃ SiO _3/2 ) ((CH ₃ ) ₂ SiO) ₆
1 part by weight of an organosiloxane represented by ((CH ₃ ) ₃ SiO _1/2 ) ₃ and (CH ₃ ) ₃ SiO ((CH ₃ ) ₂ SiO) ₂ Si
Alkaline polymerization was carried out using 0.4 parts by weight of an organosiloxane represented by (CH ₃ ) ₃ , and a branched polyorganosiloxane (A
-4) was obtained. Adjustment example (CH ₃ ) ₃ Consists of SiO _1/2 unit and SiO ₂ unit, SiO ₂
A 60% xylene solution of polymethylsiloxane (resin) containing 0.5 mol of (CH ₃ ) ₃ SiO _1/2 units per 1 mol of units was heated and stirred to completely remove xylene, and benzene-soluble polyorganosiloxane resin (B −
1) was obtained. Similarly, for 1 mol of SiO ₂ units, (CH ₃ ) ₃ SiO _1/2 units are 0.6 mol, 0.65 mol, 0.8 mol,
1 mol of benzene-soluble polyorganosiloxane resins (B-2 to B-5) was obtained. Examples Branched polyorganosiloxanes (A-1 to A-4) obtained in Synthesis Examples 1 to 4 and benzene-soluble polyorganosiloxanes (resins) obtained in Preparation Examples (B
-1 to B-5) in the combinations and amounts shown in the table below, and then add fine Teflon powder and fine silica powder treated with octamethylcyclotetrasiloxane or lithium stearate in the amounts shown in the table below. After heating and kneading, samples S-1 to S-7 were obtained using a triple roll. As comparative examples, comparative samples R-1 and R-2 were obtained by using linear polydimethylsiloxanes having trimethylsilyl groups at both ends and having a viscosity of 100,000 cSt and 10,000 cSt at 25° C. instead of the branched polyorganosiloxanes. Furthermore, as a comparative example, polybutene "Polybis 200N" with a viscosity of 100,000 cSt at 25°C was used instead of the branched polyorganosiloxane and benzene-soluble polyorganosiloxane (resin) mixture.
(trade name of polybutene manufactured by Nippon Oil & Fats Co., Ltd.)
Comparative Example Sample R-3 was obtained. The following experiment was conducted to investigate the characteristics of the grease thus obtained. A shaft (made of aluminum) with a diameter of 4.95 mm and a length of 13.5 mm is installed on a bearing (made of brass) with a diameter of 5 mm and a length of 11.8 mm.
-1 to S-7 and comparative samples R-1 to R-3 were applied, respectively, and then rotated at a torque rotation speed of 20 rpm. The torque values after 60 seconds (initial stage), 10 minutes, 20 minutes, and 30 minutes, and the torque value at -30°C are also listed in the following table.

【table】

【table】

Claims (1)

[Claims] 1 (A) Average compositional formula (R ¹ SiO _3/2 ) _l (R ² ₂ SiO) _n (R ³ ₃
SiO _1/2 ) _o (wherein R ¹ , R ² and R ³ are each a monovalent group selected from the group consisting of an alkyl group having 1 to 30 carbon atoms, a substituted and unsubstituted aryl group, is a number from 1 to 4, m is a number selected to achieve the required viscosity range, and n is a number from 1 to 6)
and the viscosity at 25℃ is 100~
500000cSt Branched Polyorganosiloxane 100
(B) consists of R ⁴ ₃ SiO _1/2 units and SiO ₂ units, and has OR ⁵ groups bonded to Si atoms (provided that R ⁴ is a monovalent hydrocarbon group that is the same or different from each other) ,
R ⁵ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms), R ⁴ ₃ SiO _1/2 per mol of SiO ₂ unit
Benzene-soluble polyorganosiloxane (resin) 1-250 with a unit mole number of 0.4-2.0 moles
and (C) 2 to 180 parts by weight of a thickener.