JPH0273893A - Silicone oil composition for fluid coupling - Google Patents

Abstract

PURPOSE:To provide the subject composition containing a high viscous dimethyl polysiloxane and a low viscous methyl group- or phenyl group-containing organopolysiloxane in a specified ratio and having viscosity-temperature characteristics and long-period durability against oxidation and thermal decomposition at high temperatures. CONSTITUTION:An objective composition containing (A) 95-75wt.% (preferably 95-80wt.%) dimethyl polysiloxane with a high viscosity (e.g., 5000-1000000cst) and (B) 5-25wt.% (preferably 5-20wt.%) methyl group- and/or phenyl group- containing organopolysiloxane with a low viscosity (e.g., 100-5000cst at 25 deg.C).

Description

DETAILED DESCRIPTION OF THE INVENTION (Objective of the Invention) (Industrial Application Field) The present invention is a fluid coupling (also called a viscous coupling (VC)) as a torque transmission means.

), and more specifically, it relates to a silicone oil composition for fluid couplings that has excellent viscosity-temperature characteristics and is resistant to oxidation and thermal decomposition during long-term use at high temperatures.

(Prior art and its problems) A fluid coupling (VC) includes, for example, a plurality of outer plates fixed to a drive shaft side with a certain gap, and a driven shaft movably arranged between the outer plates. A plurality of installed inner plates are accommodated in the housing,
It is constructed by filling this with viscous fluid for torque transmission. A shearing force, that is, a shearing torque, is generated in the plate group due to the difference in rotational speed between the driving shaft and the driven shaft, and the torque is transmitted to the driven shaft.

The properties of the working fluid used in fluid couplings as described above include: - Small viscosity change due to temperature changes (small viscosity-temperature coefficient), - Stability against heat and oxidation, - Purpose of use It is required to have a sufficient viscosity to suit the conditions, - have flexibility in selecting the viscosity, and - have small changes in viscosity due to shearing.

Dimethylpolysiloxane is generally used as a working fluid for this type of fluid coupling in consideration of the above-mentioned required performance.

However, under severe usage conditions of fluid couplings, specifically at high temperatures of 200°C or higher, dimethylpolysiloxane rapidly loses its viscosity stability and thickens, making it difficult for normal torque transmission. cause serious trouble. This is because dimethylpolysiloxane deteriorates due to heat and oxygen on the high temperature side, becoming three-dimensional and gelling.

In order to deal with this, various antioxidants and heat resistance improvers are added, or
No. 2, No. 1, pp. 10-13, proposes a silicone oil composition comprising a combination of specific amounts of two or more types of methyl group- and/or phenyl group-containing organopolysiloxanes having significantly different viscosities.

The mixed organopolysiloxane described above contains (a) a high viscosity organopolysiloxane containing methyl groups and/or phenyl groups (80 to 20 parts by weight), and (b) a low viscosity organopolysiloxane containing methyl groups and/or phenyl groups. Organopolysiloxanes containing methyl groups and/or phenyl groups are commercially available, consisting of 20 to 80 parts by weight, specifically high viscosity dimethylpolysiloxane-low viscosity dimethylpolysiloxane, Alternatively, high viscosity methylphenylpolysiloxane and low viscosity methylphenylpolysiloxane, organopolysiloxanes having different viscosities but the same composition are used. However, in the case of fluid couplings that require high transmission forces, 10,0
A fluid with a viscosity of 00C3t (25°C) or higher is required, and a combination of dimethylpolysiloxanes does not have sufficient heat resistance, and a combination of methylphenylpolysiloxanes does not have sufficient viscosity-temperature characteristics.

(Problems to be Solved by the Invention) As a result of intensive studies to solve the problems of the working fluid for fluid couplings described above, the present inventors adopted dimethylpolysiloxane as a high-viscosity organopolysiloxane and focused on the fact that methylphenylpolysiloxane, which shares methyl and phenyl groups, has better oxidation and thermal stability than dimethylpolysiloxane, and by blending a specific amount of methylphenylpolysiloxane, a product with excellent heat resistance and viscosity-temperature characteristics was created. It was discovered that a fluid can be obtained.

An object of the present invention is to provide a silicone oil composition for fluid couplings that is stable against oxidation and thermal decomposition, especially during long-term use at high temperatures.

(Structure of the Invention) (Means for Solving the Problems) To summarize the present invention, the present invention has the following features: (1) High viscosity (for example, 5,000 to 1,000,000
(2) low viscosity (
For example, organopolysiloxane containing methyl groups and/or phenyl groups with a viscosity of 5 to 25% by weight The present invention relates to a silicone oil composition for fluid couplings that has excellent temperature characteristics and excellent durability.

Hereinafter, the configuration of the present invention will be explained in detail.

The high viscosity dimethylpolysiloxane used in the silicone oil composition for fluid couplings of the present invention is known per se. Since dimethylpolysiloxane has excellent viscosity-temperature characteristics over a wide temperature range, it is preferred as a working fluid for fluid couplings. Torque transmission in fluid couplings is based on viscosity, and from the viewpoint that the fluid needs to have a viscosity that changes little with temperature changes, in the present invention, 5,000 to 1,000,000 c
st (25°C) dimethylpolysiloxane is used.

However, as mentioned above, the dimethylpolysiloxane component lacks stability at high temperatures. Therefore, in the present invention, low viscosity methylphenylpolysiloxane or diphenylpolysiloxane is mixed in order to improve stability at high temperatures, thereby improving heat resistance while maintaining viscosity-temperature characteristics.

Organopolysiloxanes containing low viscosity methyl groups and/or phenyl groups are also well known and have excellent high temperature oxidation stability. In the present invention, 100 to 5,000
cst (25°C) is used. In the methylphenylpolysiloxane component, the content of phenyl groups is not particularly limited, but if the content of fer groups becomes excessive, it worsens the temperature dependence of viscosity (increases the viscosity reduction rate). It is preferably 20 to 25 mol% or less.

In the silicone oil composition for fluid couplings of the present invention, the blending amounts of the high viscosity dimethylpolysiloxane and the low viscosity methyl group- and/or phenyl group-containing organopolysiloxane are as follows: (1) The high viscosity dimethylpolysiloxane is used for torque transmission. (11) On the other hand, low-viscosity polysiloxanes containing methyl and/or phenyl groups have the opposite properties. Although the viscosity and temperature characteristics are worse than dimethylpolysiloxane, by limited use of methylphenylpolysiloxane, which has excellent oxidation and thermal stability, it has excellent viscosity and temperature characteristics and excellent heat resistance. It is determined by taking into consideration things such as the fact that the fluid can be made into a From the above viewpoint, it is desirable to use as much high viscosity dimethylpolysiloxane as possible, but in the present invention, it is 95 to 75% by weight, preferably 95 to 80% by weight.
Use weighted %. On the other hand, the low viscosity organopolysiloxane containing methyl groups and/or phenyl groups is used in an amount of 5 to 25% by weight, preferably 5 to 20% by weight. Incidentally, if the amount of the latter used is less than 5% by weight, no heat resistance effect will be exhibited, and if it exceeds 25% by weight, excellent viscosity-temperature characteristics will not be obtained.

The preferred viscosity range of the silicone oil composition for fluid couplings comprising the above-described high viscosity dimethylpolysiloxane and low viscosity methyl group- and/or phenyl group-containing organopolysiloxane of the present invention is io, ooo to 600.000 cs.
t (25°C).

In addition to the essential components of the above-mentioned high viscosity dimethyl polysiloxane and low viscosity methyl group- and/or phenyl group-containing organopolysiloxane, the silicone oil composition for fluid couplings of the present invention is particularly suitable for use under severe usage conditions such as high temperatures. Heat resistance improvers, antioxidants, etc. can be added to develop stable torque transmission characteristics.

Heat resistance improvers of this type include various organic transition metal compounds, such as various organic acid salts of iron such as iron octoate, iron naphtonite, ferrocene, iron caproate, and iron toluylate; titanium, chromium, cobalt, nickel, copper, and zirconium. , organic acid salts of various transition metals such as cerium, yttrium, and lanthanum (cerium octoate, zirconium octoate, etc.); Special Publication No. 56-14700
Heterosiloxane compounds (ferro-siloxane, zirconium-siloxane, cerium-siloxane, etc.) disclosed in No. 1, No. 51-24377, No. 53-980, etc.; N-phenylaminophenyl groups bonded within the molecule. These include siloxane.

In addition, examples of antioxidants include amine antioxidants such as free radical-scavenging phenyl-α-naphthylamine and P-isopropoxydiphenylamine, and phenolic antioxidants such as 2,6-di-t-butylphenol and styrenated phenol. Agents are useful.

In particular, as described above, the present invention uses dimethylpolysiloxane as the main component as a silicone base oil, and the deterioration of the dimethylpolysiloxane at high temperatures is caused by (a) hydrogen handling from methyl groups by M atoms. Generation of radicals and autoxidation reactions based thereon; (b) three-membered ring in dimethylpolysiloxane main chain;
Formation of a cyclic siloxane such as a four-membered ring, and ring-opening polymerization of a cyclic siloquiline moiety. Therefore, it is preferable to use the above-mentioned heat resistance improver and a free radical-scavenging antioxidant in combination. . These stabilizers may be blended in a proportion of 0.01 to 2.0% by weight, respectively, based on the base oil.

The silicone oil composition for fluid couplings obtained as described above has stable torque transmission characteristics over a long period of time with little viscosity fluctuation even under severe conditions of high temperature and high shear rate. Therefore, the silicone oil composition for fluid couplings of the present invention can be applied to, for example, fluid couplings for center differentials, rear differentials, and front differentials of passenger cars, and can improve easy drive and safety drive. can.

(Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 A mixture of 80% by weight of dimethyl silicone (DNS) having a kinematic viscosity of about 300,000 cst at room temperature and 20% by weight of methylphenyl silicone (IPs) having a kinematic viscosity of about 1,000 cst at room temperature was used as a sample oil (at room temperature). about 100
．． 000cst of the present invention) and about 100.0 at room temperature.
Using OOcst dimethyl silicone (DNS for comparison), the time required for gelation and the viscosity-temperature coefficient (V, T, C) were measured in the following manner.

・Take about 3 (IJ) of sample oil in a 100 cc beaker (inner diameter 5 cm), place it horizontally in an air circulation precision constant temperature oven, heat it at a predetermined temperature, and measure the time required for gelation. It was measured.

・Viscosity-temperature coefficient (VJ, C) For each sample oil, the viscosity-temperature coefficient (V, T
, C) were measured.

The results are shown in Tables 1 and 2.

(Margins below) Table 1 Example 2゜ As sample oils, 80% by weight of dimethyl silicone (D) (S) having a kinematic viscosity of about 30,000 cst at room temperature and methylphenyl silicone (M) having a kinematic viscosity of about 500 cst at room temperature
PS) mixture with 20% by weight (approx. 12.500c at room temperature)
Example 1.st of the present invention) and dimethyl silicone (comparative D) Is) of about 12.500 cst at room temperature. A similar experiment was conducted.

The results are shown in Tables 3 and 4.

Table 2 Table 3 (Unit: Time) Table Next, each sample oil was subjected to a constant shear rate of 5 x 103 SeC, the time required for gelation was measured, and the stability under shear was compared.

The results are shown in Table 6.

Example 3 To each of the sample oils used in Example 2, 0.2% by weight of phenyl-α-naphdylamine was added as an antioxidant, and the gelation time at a predetermined temperature i of 250°C was measured.

The results are shown in Table 5.

Table 5 (unit: hours) Table 6 (unit: 2 hours) Example 4゜As a sample oil, dimethyl silicone (DH3) having a kinematic viscosity of about 60.000 cst at room temperature was 90% by weight and about 1,000 cst at room temperature. 000cst methylphenyl silicone (
MPS) 10% by weight (approximately 50.0OOOO at room temperature)
cst of the present invention) and about 50% at room temperature. ooocs
Example 1.t dimethyl silicone (DNS for comparison) was used. The gelation time and V, T, and C were determined in the same manner as above.

The results are shown in Tables 7 and 8.

Diphenylamine was added as an inhibitor in the amount of 0.2% by weight, and the gelation time was measured at a predetermined temperature of 250°C.

The results are shown in Table 9.

Table 9 (Unit: Time) Table Example 5゜Example 4. Each of the sample oils used in the above was oxidized and then subjected to a constant shear rate of 5 x 103 SeC, the time required for gelation was measured, and the stability under shear was compared.

The results are shown in Table 10.

(Margin below) Table 10 The results are also shown in Table 11.

(Units: hours) Table 11 (Units: hours) Example 6゜ As sample oil 1, dimethyl silicone (DNS > 80% by weight and about 500cst) of about 30,000 cst at room temperature
4.4'-thio-bis-(4,4'-thio-bis-(
3-methyl-6-t-butylphenol) (A) to 0,
Cerium octoate (2% by weight added to the base oil)
B) with 0.2% by weight added and 4.4° to the base oil.
-thio-bis-(3-methyl-6-t-butylphenol) (A) and cerium octoate (B) at 0.1 each
Products (products of the present invention) were prepared by adding each weight %, and the gelation time of each product was measured in the same manner as in Example 1.

〔Effect of the invention〕

The silicone oil composition for fluid couplings of the present invention, which contains a specific amount of high-viscosity dimethylpolysiloxane and low-viscosity organopolysiloxane containing methyl groups and/or phenyl groups, has excellent viscosity-temperature characteristics. , exhibits excellent durability against oxidation and thermal decomposition during long-term use at high temperatures.

Therefore, the silicone oil composition for fluid couplings of the present invention is extremely useful, particularly for fluid couplings (VC) that operate under severe conditions such as high temperatures and high shear rates.

Patent applicant: Toa Fuel Industries Co., Ltd.

Claims (1)

[Claims] 1. (1) High viscosity dimethylpolysiloxane...95
~75% by weight (2) Low viscosity methyl group- and/or phenyl group-containing organopolysiloxane 5-25% by weight Silicone for fluid couplings with excellent viscosity-temperature characteristics and durability oil composition. 2. The viscosity of dimethylpolysiloxane is 5,000 to 1,
000,000 cst (25°C), the viscosity of the organopolysiloxane containing methyl groups and/or phenyl groups is 10
The silicone oil composition for fluid couplings according to claim 1, which has a silicone oil composition of 0 to 5,000 cst (25°C).