JPS61157587A - Acid-resistant heat-dissipating grease - Google Patents

Abstract

PURPOSE:A heat-dissipation silicone grease that is composed of a specific polyorganosiloxane and a metal oxide at a specific ratio, thus resisting acidic conditions such as die casting of anodized aluminum without deterioration. CONSTITUTION:The objective grease is composed of (A) 10-50wt%, preferably 10-30wt% of a polyorganosiloxane of formula I [R<1> is 4-16C alkyl; R<2> is 2-phenylethyl, 2-phenylpropyl; m+n is 10-1,000; 0.3<=n/(m+n)<1.0] such as a straight-chain polyorganosiloxane and (B) 90-50wt%, preferably 90-70wt% of a metal oxide, preferably zinc oxide or alumina.

Description

[Detailed Description of the Invention] [Technical Field of Kaimei] The present invention relates to a heat dissipating grease with good thermal conductivity, and more specifically to a heat dissipating silicone that does not deteriorate even under acidic conditions, such as anodized die-cast aluminum. It concerns grease.

[Technical background of the invention and its problems] Conventionally, release silicone greases have been known that are prepared by adding a metal oxide having good thermal conductivity to a polyorganosiloxane such as polydimethylsiloxane or polymethylphenylsiloxane. It is. However, these greases tend to cause oil separation, and when used in electronic components, the separated oil causes the junction coating materials and manufacturing materials, especially silicone resin materials, to swell and crack. .

In order to solve this problem, Japanese Patent Laid-Open No. 50-10557
No. 3 discloses a silicone grease using polymethylalkyl (c6-14) siloxane. Also, in Japanese Patent Publication No. 52-33272.

A group selected from 5 to 50 mol% of monovalent hydrocarbon groups bonded to a silicon atom from a 2-phenylethyl group, a 2-phenylpropyl group, or an alkyl group having 6 to 30 carbon atoms, with the remainder being methyl. Silicone greases using the base bo]noorganosiloxane are disclosed. However, although these greases have improved swelling properties due to oil separation, they have a problem in that they have poor heat resistance and gel when used at high temperatures for a long time.

In addition, recently, when heat dissipating silicone grease is used between a transistor, especially a device that generates a large amount of heat such as a Nokuward Run Sister, and a heat sink, most of the organosiloxane, which is the base oil of the silicone grease, is exuded. A new problem arose: storage. An investigation into the cause revealed that the alumite treatment on the surface of the radiator was carried out in a strong acid electrolytic decomposition layer, and that acid remained on the surface. It was discovered that this acid and heat generation caused a cracking reaction in polyorganosiloxane, particularly polydiorganosiloxane, which is the base oil of silicone grease, resulting in the production of low-molecular-weight siloxane, which caused the base oil to evaporate.

[Object of the Invention] An object of the present invention is to solve the above-mentioned problems and to provide a heat dissipating silicone grease that has excellent heat resistance even under acidic conditions.

[Structure of the Invention] As a result of extensive research into heat dissipating silicone grease that has excellent heat resistance even under acidic conditions, the present inventor has discovered that when a polyorganosiloxane having a specific structure is used, an acid-resistant heat dissipating grease that is significantly superior The present invention was completed based on the discovery that the following can be obtained.

That is, the acid-resistant heat dissipating grease of the present invention has the following formula (A):
-phenylethyl group or 2-phenylpropyl group, m
+n is an integer from 10 to 1.000 (7), and 0.3≦m+.

<1.0) 10 to 50% by weight of polyorga/siloxane
, and (B) 90 to 50% by weight of metal oxide.

The polyorganosiloxane (A) used in the present invention is
This is a compound represented by the above general formula.

In the above formula, R1 is a group for imparting acid resistance to silicone grease, and is an alkibbutyl group having 4 to 16 carbon atoms,
Examples include pentyl group, hexyl group, heptyl group, octyl group, dodecyl group, and stearyl (octadecyl) group. On the other hand, ) 12 is a group for imparting heat resistance to silicone grease, and is a 2-phenylethyl group or a 2-phenylethyl group.
- phenylpropyl group. m+n is lO ~ 1,0
It is an integer of 00, preferably an integer of 10 to 200. m
If +n is less than 10, the viscosity of the polyorganosiloxane will be too low, making it impossible to obtain a silicone grease with the expected consistency; if it exceeds 1.000, the viscosity of the polyorganosiloxane will become too high, so filling with metal oxides, etc. It becomes difficult to prepare silicone grease by adding agents. Further, m and n must satisfy the relationship 0.3≦1+1<1.0. If -1- is less than 0.3, the number of 2-phenyl ethyl groups or 2-phenylpropyl groups will be too small and it will not be possible to obtain a silicone grease with sufficient heat resistance. In this case, there is no alkyl group having 4 to 16 carbon atoms i&-, h *No acidity is imparted.

The metal oxide (B) used in the present invention imparts appropriate consistency to the polyorcasiloxane (A), and
It is a component for imparting thermal conductivity. Such metal oxides include zinc oxide, alumina, titanium dioxide,
Beryllium oxide, magnesium oxide, nickel oxide, vanadium oxide.

Examples include copper oxide, iron oxide, silver oxide, etc., but preferred are zinc oxide and alumina, which are non-toxic and can be blended in large amounts.

The blending ratio of component (A) and component CB is 10% of component (A).
~50% by weight, component (B) can be varied within the range of 90 to 50% by weight depending on the viscosity and type of component (A), the type of component (B), or the consistency of the silicone grease at a given ψ. I can do it. (B) I! The blending amount of t, min is 5
If the content is 0% by weight, sufficient thermal conductivity cannot be obtained, and it is difficult to incorporate component (B) in an amount exceeding 90% by weight. In order to obtain silicone grease with particularly high thermal conductivity, 10 to 30% by weight of component (A) and 90% of component (B) are required.
It is preferable to blend it in a proportion of ~70% by weight.

The uninvented silicone grease contains component (A) and component (B).
) The ingredients are mixed uniformly, the mixture is placed in a heating pot equipped with a stirrer, heated and stirred at 100 to 150°C, cooled, and homogenized through a triple roll, paint roll, etc., or (A) It can be prepared by mixing the components and component (B) and homogenizing the mixture by passing it through a Miki roll, a paint roll, etc. several times.

The grease of the present invention may optionally contain various additives that are added to ordinary greases, such as amine compounds such as isopropoxydiphenylamine and phenyl-α-naphthylamine, selenium compounds, dilaurylselenide, etc. It is possible to add antioxidants and the like.

[Effects of the Invention] The silicone grease of the present invention has extremely excellent heat resistance even under acidic conditions, and also has good thermal conductivity. Therefore, the acid-resistant heat dissipating grease of the present invention is useful, for example, as a heat dissipating grease for attaching a semiconductor to a heat radiator of a semiconductor device, particularly a heat radiator coated under strongly acidic conditions.

[Examples of the Invention] The present invention will be explained below with reference to Examples. In the examples, all parts are parts by weight, and Me represents a methyl group.

Further, the consistency was measured according to JIS K 2220.

Example 1 75 parts of zinc oxide was added to 25 parts of the linear polyorganosiloxane represented by the formula, heated and kneaded at 150°C for 2 hours, homogenized with three rolls, and sample 1 with a consistency of 30B was prepared. Obtained. The thermal conductivity of sample 1 is 2. OX 10'4ca l
/cm SL1°C.

For comparison, polydimethylol 0C with a viscosity of 10,000 cP was heated and kneaded for 2 hours, and then homogenized using three rolls to obtain a comparative example sample 1 with a consistency of 270. Comparative example sample l
The thermal conductivity of is 1.8X 1 (1' cal/cm*
s*” was 0.

Sample 1 and comparative sample 1 were subjected to alumite treatment (
After degreasing the aluminum plate with alkali, it is washed with water and neutralized.
temperature! Used as an anode plate in 20% sulfuric acid at 8°C.
After performing electrolytic oxidation with 8A/A, 12A DC, washing with water, and sealing with pressurized steam.)
Coated on aluminum die-cast, 150
When left for 24 hours at .degree. C., most of the oil in Comparative Sample 1 evaporated, leaving only zinc oxide, and it lost its greasy appearance. Regarding Sample 1, there was no change at all, and it remained greasy.

Furthermore, for comparison, 70 parts of zinc oxide was added to 30 parts of the linear polyorganosiloxane represented by the formula, stirred, and then homogenized with a three-roll roll to obtain Comparative Example Sample 2 with a consistency of 303.

The thermal conductivity of Comparative Example Sample 3 is 1.9X 1 (1' ca
l/c+ss s・℃.

When Sample 1 and Comparative Sample 2 were each coated on an alumite-treated Fulumi die-cast surface and left at 150° C. for 24 hours, about half of the oil in Comparative Sample 2 evaporated.

However, Sample 1 did not change at all and remained greasy.

75 parts of zinc oxide was added to 25 parts of the linear polyorganosiloxane shown in Example 2, stirred, and then homogenized with a Miki roll to obtain Sample 2 with a consistency of 300. The thermal conductivity of sample 2 is 2. OX 1 (1' cal/c■・S・℃).

For comparison, 75 parts of zinc oxide was added to 25 parts of the linear polyorganosiloxane represented by the formula, stirred, and then homogenized with a Miki roll to obtain Comparative Example Sample 3 with a consistency of 310.

The thermal conductivity of Comparative Example Sample 3 is as follows: 2. OX 1(1'
cal/cues was 11°C.

When Sample 2 and Comparative Sample 3 were each coated on an alumite-treated aluminum plate and left at 200°C for 72 hours, Comparative Sample 3 completely solidified and peeled off from the aluminum plate, but Sample 2 did not. The surface was only slightly gelled, and the inside remained greasy.

Example 3 70 parts of a mixture of zinc oxide and aluminum oxide at a weight ratio of 3:1 was added to 30 parts of the linear polyorganosiloxane represented by the formula, stirred, and then homogenized with a Miki roll to obtain a consistency of 330. Sample 3 was obtained. The thermal conductivity of Sample 3 was 2.2X 10" cal/cm @'s e°C.

When Comparative Example Sample 3 and Sample 3 were respectively coated on an alumite-treated aluminum plate and left at 200"C for 72 hours, Comparative Example Sample 3 completely gelled and peeled off from the aluminum plate, but Sample 3 did not. The surface was only slightly gelled, and the inside remained greasy.

Example 4 75 parts of zinc oxide was added to 25 parts of the linear polyorganosiloxane represented by the formula, and the mixture was heated and stirred at 120°C.

Sample 4 was homogenized with an aqua regia roll and had a penetration of 290.

The thermal conductivity of sample 4 is 2. OX 10'''1cal/aw
It was eS・℃.

For comparison, 70 parts of zinc oxide was added to 30 parts of the linear polyorganosiloxane represented by the formula, heated and stirred at 120°C, and then homogenized with a Miki roll to obtain Comparative Example Sample 4 with a consistency of 310. The thermal conductivity of Comparative Example Sample 4 is 1.9X 10-c
al/cme S @ “Cte was there.

When each coating was applied onto an alumite-treated aluminum die-cast surface and left at 150°C for 24 hours, in Comparative Example Sample 4, about half of the oil content evaporated, and the content of lead oxide increased, resulting in a grease-like appearance. I had lost it. However, Sample 4 did not change at all and remained greasy.

Claims (1)

[Claims] 1. (A) General formula ▲ There are numerical formulas, chemical formulas, tables, etc. ▼ (In the formula, R^1 is an alkyl group having 4 to 16 carbon atoms, R^2
is a 2-phenylethyl group or a 2-phenylpropyl group, m+n is an integer from 10 to 1,000, and 0.3≦n/(
m+n)<1.0) 10 to 50% by weight of polyorganosiloxane
, and (B) 90 to 50% by weight of a metal oxide. 2. The acid-resistant heat dissipating grease according to claim 1, wherein the metal oxide (B) is zinc oxide or alumina. 3. The blending ratio of components (A) and (B) is (A) 10 to 30
The acid-resistant heat dissipating grease according to claim 1, wherein (B) is 90 to 70% by weight.