JPH0665505A - Organopolysiloxane composition for viscous fluid coupling - Google Patents

Abstract

PURPOSE:To provide a composition for viscous fluid coupling which in reduced in viscosity increase or decrease under high-temp. and high-shear conditions to cause little torque change and can withstand long-term use. CONSTITUTION:This composition comprises a liquid organopolysiloxane represented by the formula R<1>a R<2>b SiO[4-(a+b)]1/2 (wherein R<1> is an alkyl, R<2> is an aryl, a+b=1.95-2.05, and b/(a+b)=0.05-0.30) and either a compound represented by the formula (wherein R<3>s are the same or different alkyl groups) or a polymer thereof.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an organopolysiloxane composition for viscous fluid couplings.
The present invention relates to an organopolysiloxane composition for viscous fluid joints, which has little increase in viscosity and decrease in viscosity under high temperature and high shear and is stable for a long time.

[0002]

2. Description of the Related Art Conventionally, as a fluid used for a viscous fluid coupling, it has a proper viscosity, a high flash point, is stable against oxidation and thermal decomposition, and has a small temperature dependence of viscosity. Organopolysiloxane fluids are commonly used because of the properties required. However, due to severe shearing and heat generation due to friction generated in the fluid coupling, the organopolysiloxane fluid alone has a drawback in that viscosity increase or gelation or the like occurs after a certain period of time and the function as the fluid coupling is lost. . Therefore, a method of adding various antioxidants to the organopolysiloxane fluid and blending them to prevent their deterioration is being studied. For example, JP-B-55-18457 and JP-B-63-
In JP 19538, a dimethylpolysiloxane composition having a low viscosity increase under high temperature conditions can be obtained by adding and blending dimethylpolysiloxane having a low degree of polymerization modified with an aromatic amine compound to a dimethylpolysiloxane fluid. It is disclosed.

[0003]

However, the dimethylpolysiloxane compositions obtained by these methods are all dimethylpolysiloxanes having a low degree of polymerization modified with an aromatic amine compound under high temperature and high shearing force. Undergoes a rearrangement reaction with the dimethylpolysiloxane fluid of the base oil, and the viscosity of the dimethylpolysiloxane fluid itself decreases. Therefore, when this is used as a viscous fluid coupling, there is a drawback that the torque transmission rate decreases and the fluid coupling loses its function. Further, in order to produce a low degree of polymerization dimethylpolysiloxane modified with an aromatic amine compound, a complicated procedure is required, so that the dimethylpolysiloxane composition obtained by this method has a drawback of high cost. there were. The present inventors have arrived at the present invention as a result of extensive studies to solve the above-mentioned drawbacks. That is, an object of the present invention is to provide an organopolysiloxane composition for viscous fluids, which has little increase in viscosity and decrease in viscosity under high temperature and high shear, has almost no torque fluctuation, and can withstand long-term use. .

[0004]

Means for Solving the Problem and Its Action The above-mentioned object is (A) the general formula R ¹ _a R ² _b SiO _{[4- (a + b)] / 2} (wherein R ¹ is an alkyl group, R ² is an aryl group, a + b = 1.
95-2.05, b / (a + b) = 0.05-0.30. ) Organopolysiloxane fluid 100 represented by
Parts by weight and (B) general formula

[Chemical 2] (In the formula, R ³ is the same or different alkyl groups.) Or its polymer 0.01 to 5
The present invention relates to an organopolysiloxane composition for viscous fluid couplings, characterized in that the composition comprises parts by weight.

To explain this, it is used in the present invention.
The organopolysiloxane as the component (A) is the main ingredient of the composition of the present invention, and in the above formula, R ¹ is an alkyl group exemplified by a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group and the like. And of these, a methyl group is preferable. R ² is an aryl group exemplified by a phenyl group and a tolyl group, and among them, a phenyl group is preferable. a + b is a number from 1.95 to 2.05. b / (a +
b) shows the amount of aryl groups with respect to all organic groups. As this value increases, the temperature viscosity coefficient increases,
Viscosity decreases significantly at high temperatures, which impedes torque transmission. On the other hand, when this value is small, a sufficient effect of improving heat resistance is not recognized, and the dissolving ability of the component (B) is also reduced.
Therefore, the value of b / (a + b) is in the range of numbers of 0.05 to 0.30, preferably in the range of 0.05 to 0.20. Examples of such a diorganopolysiloxane include a dimethylsiloxane / methylphenylsiloxane copolymer capped with trimethylsiloxy groups at both ends, a dimethylsiloxane / diphenylsiloxane copolymer with trimethylsiloxy groups blocked at both ends, and a dimethylsiloxane with dimethylphenylsiloxy groups blocked at both ends. -Methylphenylsiloxane copolymer, dimethylphenylsiloxy group-capped dimethylsiloxane-diphenylsiloxane at both ends, and the like are exemplified.
The viscosity of this component is not particularly limited, but it is preferably within the range of 100 to 1,000,000 centistokes at 25 ° C from the viewpoint of torque transmission, and more preferably within the range of 500 to 500,000 centistokes. Is. In the composition of the present invention, the above (A)
The components may be used alone, as a mixture of two or more kinds having different viscosities, or as a mixture of two or more kinds having different chemical structures.

The component (B) used in the present invention is a component which is a feature of the present invention.

[Chemical 3] (In the formula, R ³ is an alkyl group exemplified by a methyl group, an ethyl group, a propyl group, an isopropyl group, an octyl group and a nonyl group, and these R ³ may be the same or different from each other.). It is the compound shown or its polymer. A typical example of such a compound is quinoline,
There are 1,2-dihydro-2,2,4-trimethyl-, homopolymers. The addition amount of this component is 0.01 to 5 parts by weight based on 100 parts by weight of the component (A). This is because when the compounding amount is less than 0.01 part by weight, the action and effect due to the addition of this component are not recognized, and when it exceeds 5 parts by weight, the solubility of this component in the component (A) becomes poor. This is because there is a risk that it may be difficult to obtain a uniform organopolysiloxane composition.

The composition of the present invention comprises the above-mentioned component (A) and (B).
It can be easily produced by uniformly mixing a predetermined amount of the ingredients with heating. In this case, since the component (B) is usually solid, it is advantageous to mix the component (B) under a temperature condition at which the component (B) is melted or higher. The heating temperature at this time is generally in the range of 60 to 130 ° C, preferably 90 to 130 ° C. Further, in this mixing, a part of the component (A) and the component (B) may be uniformly mixed in advance and then the remaining component (A) may be mixed.

[0008]

EXAMPLES The present invention will now be described in detail with reference to Examples.
In the examples, “part” means “part by weight”, viscosity is measured at 25 ° C., and “cs” is centistokes.

[0009]

Example 1 80 parts of a dimethylsiloxy group-capped dimethylsiloxane / diphenylsiloxane copolymer having a viscosity of 7000 cs (diphenylsiloxane unit content of 15 mol%) was added to 80 parts of a dimethylsiloxy group-capped dimethylsiloxane / diphenylsiloxane having a trimethylsiloxy group of 130 cs. Copolymer (diphenylsiloxane unit content 15
20 parts by mole to give an organopolysiloxane fluid having a viscosity of 4200 cs. Then 100 parts by weight of this organopolysiloxane fluid was added to the formula

[Chemical 4] Red-brown powder that is a low polymer of the compound shown in [Quinol
ine, 1,2-dihydro-2,2,4-trimethyl-, homopolymer; (Poly
merized2,2,4-trimethyl-1,2-dihydroquinoline), softening point 65-110 ° C, polymerization degree 2-4]
In an atmosphere of nitrogen, the mixture was stirred at 100 ° C. for 5 minutes and uniformly mixed to prepare an organopolysiloxane composition for viscous fluid coupling. 30 g of the organopolysiloxane composition for a viscous fluid coupling was placed in a 100 ml beaker and left in a hot air circulation oven at 280 ° C., and the change in viscosity with time was measured (Test 1). Further, 80 g of each of these compositions was injected into a fluid coupling device and continuously operated at an ambient temperature of 280 ° C./3000 rpm to measure the time until the organopolysiloxane composition for viscous fluid coupling gelled (Test 2). Table 1 below shows these results as Test 1 and Test 2, respectively.
It was shown to. In Table 1, the maximum viscosity decrease rate is the rate of change in viscosity when the maximum decrease in viscosity was obtained during the test.
The maximum viscosity lowering time is the time until the viscosity becomes the minimum, and the gelling time is the time until the viscosity rises and the fluidity is lost.

[0010]

Example 2 A low polymer of the compound represented by the formula used in Example 1 was added to 100 parts of a dimethylsiloxy / diphenylsiloxane copolymer having a viscosity of 10,000 cs and having trimethylsiloxy groups at both ends blocked (diphenylsiloxane unit content: 10 mol%). 0.5 part of the reddish brown powder was added and mixed under stirring in a nitrogen atmosphere at 100 ° C. for 5 minutes to prepare an organopolysiloxane composition for a viscous fluid coupling. The characteristics of this composition were measured in the same manner as in Example 1, and the results are shown in Table 1 below.

[0011]

Example 3 A low polymer of the compound represented by the formula used in Example 1 was added to 100 parts of a dimethylsiloxane / diphenylsiloxane copolymer capped with trimethylsiloxy groups at both ends and having a viscosity of 10,000 cs (diphenylsiloxane unit content: 15 mol%). 0.5 part of the reddish brown powder was added, and the mixture was stirred and mixed at 100 ° C. for 5 minutes in a nitrogen atmosphere to prepare an organopolysiloxane composition for viscous fluid coupling.
The characteristics of this composition were measured in the same manner as in Example 1, and the results are shown in Table 1.

[0012]

Comparative Example 1 An organopolysiloxane composition for a viscous fluid coupling was prepared in the same manner as in Example 1 except that the reddish brown powder which was a low polymer of the compound represented by the formula was not added. The characteristics of this composition were measured in the same manner as in Example 1, and the measurement results are shown in Table 1.

[Table 1]

[0013]

EFFECTS OF THE INVENTION The organopolysiloxane composition for viscous fluid couplings of the present invention comprises the components (A) and (B), and since it contains the special compound (B), it has a high temperature. In addition, there is little increase in viscosity and decrease in viscosity under high shear, and there is almost no torque fluctuation, and it can withstand long-term use.

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Claims (1)

[Claims] 1. (A) General formula R ¹ _a R ² _b SiO _{[4- (a + b)] / 2}
(In the formula, R ¹ is an alkyl group, R ² is an aryl group, and a + b =
1.95 to 2.05, b / (a + b) = 0.05 to 0.30
Is. ) Organopolysiloxane fluid 10
0 parts by weight and (B) general formula: (In the formula, R ³ is the same or different alkyl groups.) Or its polymer 0.01 to 5
An organopolysiloxane composition for viscous fluid couplings, characterized in that it comprises 1 part by weight.