JPH0639591B2 - Silicone grease composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a silicone grease composition, and particularly to a heat-dissipating silicone grease composition having excellent thermal conductivity.

<Prior Art> Conventionally, as a heat dissipation grease based on silicone oil, there has been known one using zinc white or alumina powder as a thickener (Japanese Patent Publication No. 52-33272 and Japanese Patent Publication No. 59-52195). Further, in recent years, aluminum nitride has been developed as a thickener capable of achieving further improvement in thermal conductivity (for example, Japanese Patent Publications 60-14792 and 57).
-36302).

<Problems to be Solved by the Invention> However, since the oil holding power of aluminum nitride is not sufficient, the amount of aluminum nitride that can be contained in silicone oil has been extremely limited in the past, and therefore, aluminum nitride itself. Although it has good thermal conductivity, the thermal conductivity of the silicone grease composition has not been improved so much. For example, in the invention disclosed in Japanese Examined Patent Publication No. 60-14792, 50 to 95 parts by weight of aluminum nitride powder is added to 100 parts by weight of silicone oil. However, the addition amount is small and sufficient thermal conductivity is obtained. Can't expect improvement.

Further, in the invention described in Japanese Patent Publication No. 57-36302, the flaky aluminum nitride powder is an optional component, but since spherical silica fiber is an essential component for the purpose of improving oil holding power, it is nitrided. The content of the aluminum powder is unavoidably reduced, and it cannot be expected that the thermal conductivity is sufficiently improved.

The inventors of the present invention have conducted intensive studies to solve such drawbacks, and as a result, by combining a specific organopolysiloxane with spherical hexagonal aluminum nitride powder having a certain particle size range, an extremely large amount of silicone oil can be obtained. The present invention has been completed by finding that aluminum nitride can be contained.

Therefore, an object of the present invention is to provide a silicone grease composition having a low oil separation degree and good thermal conductivity.

<< Means for Solving the Problems >> It was achieved by a silicone grease composition consisting of 100 parts by weight of an organopolysiloxane represented by the formula and 100-900 parts by weight of spherical hexagonal aluminum nitride powder having an average particle size of 0.5-5 μm.

The organopolysiloxane as the first component in the present invention is In, R is one or more groups selected from the group of saturated or unsaturated monovalent hydrocarbon groups having 1 to 18 carbon atoms. Examples of such groups include methyl group, ethyl group, propyl group, hexyl group, octyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, saturated hydrocarbon group such as octadecyl group, vinyl group, phenyl group, Examples thereof include unsaturated hydrocarbon groups such as a chlorophenyl group and the like, with a methyl group, a phenyl group and an alkyl group having 6 to 14 carbon atoms being particularly preferable.

Also, a is 1.8 to 2.3.

The viscosity of the organopolysiloxane used in the present invention needs to be 50 to 500,000 cs at 25 ° C., particularly 100 to 100, from the viewpoint of the consistency and thermal conductivity required for the silicone grease composition. It is preferably 000 cs.

In the present invention, a spherical hexagonal aluminum nitride powder, which is particularly excellent in oil holding power, is used as the second component as the aluminum nitride powder that imparts thermal conductivity to the silicone grease composition. In this case, if the average particle size of the aluminum nitride powder is 0.5 μm or less, the thickening effect becomes too large and the grease becomes low in hardness (hard), and the grease which is preferable for use cannot be obtained. Therefore, in order to use a spherical hexagonal crystal powder having an average particle diameter of 0.5 μm or less to obtain a preferable grease for use, it is necessary to reduce the content of the aluminum nitride powder. It is not preferable because the original purpose is poor thermal conductivity. On the other hand, if the average particle size is larger than 5 μm, the uniformity of the finished grease is poor, the stability of the grease is poor, the oil separation is large, and the separation of the base oil becomes severe, which is not preferable. Therefore, in the present invention, it is necessary that the average particle size of the spherical hexagonal system used is 0.5 to 5 μm.

In order to produce the grease of the present invention, the first component and the second component are weighed and mixed with a mixer such as a planetary mixer. Further, a known third component such as an antioxidant may be added if necessary. The mixing can be performed, for example, by heating and mixing under pressure or reduced pressure, and then sufficiently kneading with a kneader such as a three-roll mill.

The grease of the present invention produced as described above has a degree of oil separation (J
IS-K-2220) is very small at 0 to 0.8% under the condition of 120 ° C./24 hours, and according to the TCW-1,000 type heat conductivity method thermal conductivity meter manufactured by Vacuum Riko Co., Ltd. For example, the thermal conductivity of conventional grease is 1.0 to 2.0 x 10
^-3 cal / cm · sec ° C., whereas in the case of the grease of the present invention, it is 2.5 to 5.5 × 10 ⁻³ cal / cm · sec ° C.
It can greatly improve its thermal conductivity.

<< Effects of the Invention >> The silicone grease composition of the present invention obtained as described above has a small oil separation degree and a small oil separation amount, and also has good thermal conductivity, which is superior to that of the conventional thermal conductive grease. Has much better performance.

<Examples> The present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto.

Examples 1-9. 100 parts by weight of various organopolysiloxanes having the viscosity shown in Table 1 were used as a base oil, and spherical hexagonal aluminum nitride powder having an average particle size shown in the same table was weighed in an amount shown in the same table. And the mixture was thoroughly mixed with a planetary mixer for 30 minutes, and then kneading with a three-roll mill was carried out three times to prepare a silicone grease composition of the present invention.

The base oils used in Table 1 are as follows.

Examples 1 to 4: Dimethylpolysiloxane blocked with trimethylsilyl groups at both ends Examples 5-7: Dimethyldecylmethylpolysiloxane blocked with trimethylsilyl groups at both ends (25 mol% decyl group) Examples 8-9: Dimethyldiphenyl blocked with trimethylsilyl groups at both ends Polysiloxane (25 mol% of phenyl groups) Each of the obtained samples was light gray in appearance and had a smooth surface, and was in the form of a uniform grease. Also, 120 ℃, 2
The oil separation degree after 4 hours was low and extremely good.

Table 2 shows the results of measuring the thermal conductivity of each sample using a TCW-1,000 type thermal conductivity measuring device (heat wire method) manufactured by Vacuum Riko Co., Ltd.

The results shown in Table 2 demonstrate that the thermal conductivity of the silicone grease composition of the present invention is remarkably excellent as compared with the conventional grease represented by Comparative Examples described below.

The measurements of the consistency and oil separation in the table are JIS-K-222.
It was done by 0.

Comparative Examples 1-6. As shown in Table 3, a sample was prepared using the base oil and the thickener in the same manner as in the example.

Consistency, oil separation and thermal conductivity of each of the obtained samples were measured in the same manner as in the examples.

The grease of Comparative Example No. 1 has good smoothness,
Sufficient thermal conductivity could not be obtained because the amount of aluminum nitride powder added was small.

The grease of Comparative Example No. 2 became too hard and had poor extensibility and could not be used.

The grease of Comparative Example No. 3 showed a good thermal conductivity, but lacked uniformity as a grease, resulting in severe oil separation after standing.

The greases of Comparative Examples Nos. 4 and 5 were those using conventional zinc white powder. In each case, the grease had excellent uniformity but low thermal conductivity.

The grease of Comparative Example No. 6 uses alumina powder, but its thermal conductivity is as low as that of zinc white, and the amount of oil separated is relatively large.

The results are summarized in Table 4, and it was confirmed that the performance of any of the samples was significantly inferior to the performance of the silicone grease composition of the present invention obtained in Examples.

The base oil used was dimethylpolysiloxane blocked with trimethylsilyl groups at both ends in Comparative Examples 1 and 2, and dimethyldecylmethylpolysiloxane blocked with trimethylsilyl groups at both terminals in Comparative Examples 3 and 4 (decyl group 25). In the case of Comparative Examples 5 and 6, it is a dimethylphenylpolysiloxane blocked with trimethylsilyl groups at both ends (phenyl group 25 mol%).

The results of the above Examples and Comparative Examples demonstrate that the performance of the silicone grease composition for heat radiation of the present invention is remarkably superior to that of conventional products.

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Claims (1)

[Claims] 1. A general formula A silicone grease composition comprising 100 parts by weight of an organopolysiloxane represented by the formula (1) and 100-900 parts by weight of spherical hexagonal aluminum nitride powder having an average particle size of 0.5 to 5 μm; Is one or two or more groups selected from the group of saturated or unsaturated monovalent hydrocarbon groups having 1 to 18 carbon atoms, and a is 1.8 to 2.3.
Is.