KR20050098035A - Thermal conductivity silicone rubber composite with carnbone nano tube - Google Patents

Abstract

The present invention is an organopolysiloxane gum having a viscosity of at least 1,000,000 mPa · s at 25 ° C., fine particles having excellent thermal conductivity; A thermally conductive silicone rubber composition comprising a carbon nanotube, graphite, alumina, a filler of titanium oxide, and an organic peroxide curing agent.

Description

Thermally Conductive Silicone Rubber Composition Containing Carbon Nanotubes {THERMAL CONDUCTIVITY SILICONE RUBBER COMPOSITE WITH CARNBONE NANO TUBE}

The present invention relates to a silicone rubber composition excellent in thermal conductivity and a method of manufacturing the same. More specifically, the present invention relates to a silicone rubber composition having excellent thermal conductivity and a method of manufacturing a thermally conductive silicone rubber by adding a small amount of carbon nanotubes and graphite having excellent thermal conductivity.Since silicone rubber has a wide temperature range for use and excellent weather resistance, Used as a thermally conductive rubber. So far it has been proposed in many thermally conductive silicone rubber compositions. For example, a mixture of alumina fine powder in liquid silicone rubber (Patent Publication No. 1996-0041280), a mixture of zinc oxide, alumina, and alumina nitride powder in liquid silicone rubber (US Pat. No. 6,114,429) and addition reaction curability Thermally conductive silicone rubber compositions (Patent Publication No. 2001-0063954) and the like are known. However, the thermally conductive silicone rubber composition prepared from such a composition requires the use of expensive liquid silicone and high content of the thermally conductive filler and is composed of a two-component type, which deteriorates the handleability and formability of the silicone rubber composition. There is this. Accordingly, the present invention relates to a thermally conductive silicone rubber composition and a thermally conductive silicone rubber composition comprising a mixture of a thermally curable organopolysiloxane gum having excellent economics and functionality and carbon nanotubes and graphite having excellent thermal conductivity.

An object of the present invention is to provide a thermally conductive silicone rubber composition having excellent thermal conductivity, excellent handleability and moldability by adding a filler having excellent thermal conductivity and a mixed powder containing a small amount of carbon nanotubes.

The present invention relates to a thermally conductive silicone rubber composition comprising an organopolysiloxane gum, a thermally conductive filler, and an organic peroxide curing agent.

There is no restriction on the type and curing method of the silicone rubber of the thermally conductive silicone rubber of the present invention. Silicone rubbers that can be used in the thermally conductive rubber composition can be broadly divided into millable type silicone gum and liquid silicone, and the curing reaction of the silicone rubber is dependent on hydroxylation, condensation and addition depending on the structure of the silicone rubber. Reaction, or radical reaction.

Organopolysiloxane gum An organic peroxide-curable millable type organopolysiloxane gum can be used, and the dimethylsilicone rubber with different organosiloxane gum chemical structures depending on the required properties, methylphenylsilicone rubber that can maintain elasticity even at low temperatures And methylvinyl silicone rubber having heat resistance, cold resistance, and radiation resistance, and fluorosilicone rubber having oil resistance can be used.

Thermally conductive fillers impart thermal conductivity to the resulting silicone rubber, for example aluminum powder, copper powder, silver powder, gold powder, nickel powder, silicon powder, nickel powder, iron powder, zirconium powder, zinc powder and other metals. Powders can be used, and alumina, magnesium oxide, zinc oxide, beryllium oxide, aluminum hydroxide, titanium oxide, chromium oxide, iron oxide and other metal oxide powders can be used, and boron nitride powder, aluminum nitride powder, titanium nitride powder and silicon nitride Powders and other metal nitride powders can be used, boron carbide powders, silicon carbide powders and other metal carbide powders can be used, and silicon carbide, boron carbide and other carbides can be used. Graphite, carbon black, carbon nanotubes and other carbon based powders can be used. The aforementioned powders may be used alone or as a mixture of two or more powders as a thermally conductive filler. There is no restriction on the average particle size of the thermally conductive filler, but 0.1 to 150 mu m is preferred. When the average particle size is 0.1 μm or less, the dispersibility is inferior, and when the average particle size is 150 μm or more, the thermal conductivity becomes poor. In addition, when graphite powder is used as the thermally conductive filler, natural graphite or artificial graphite may be used as the thermally conductive powder, and an average particle size of 0.1 to 50 µm is preferable. When the thermally conductive filler is graphite powder, it can be used at 5 to 800% by weight. When the content of graphite is less than 5% by weight, the thermal conductivity is inferior, and at a content of 800% by weight or more, the composition is inferior. When the carbon nanotube powder is used as the thermally conductive filler, the carbon nanotube powder is composed of 0.5 to 100% by weight. The amount of carbon nanotube powder is preferably 1 to 30% by weight. The carbon nanotubes used in the present invention are anisotropic materials having diameters of several to several hundred nm and lengths of several to several hundred μm, and preferably single-walled carbon nanotubes or multi-walled carbon nanotubes. Carbon nanotubes are mechanically strong (100 times of steel), have excellent chemical stability, and have excellent thermal conductivity of 2000 W / mK. Due to their hollow nature, carbon nanotubes have lower density than general carbon materials such as graphite or carbon fiber. Has In the present invention, multilayer wall carbon nanotubes (SWNT: single-wall nanotube) and multilayer wall carbon nanotubes (MWNT: multi-wall nanotube) may be used. The carbon nanotubes used as the thermally conductive fillers preferably have a diameter of 0.5 to 500 nm and a length of several hundred μm. When titanium dioxide powder is used as the thermally conductive filler, the titanium dioxide powder having an average particle size of 0.1 µm to 30 µm is composed of 1 to 400% by weight. In addition, when the alumina powder is used as the thermally conductive filler, the alumina powder having an average particle size of 1 μm to 30 μm is composed of 1 to 400 wt%. The aforementioned powders may be used alone or as a mixture of two or more powders as a thermally conductive filler. The vulcanizing agent is used at 0.1 to 10% by weight of organic peroxide. If the vulcanizing agent is less than 0.1% by weight, the physical properties of the composition are drastically degraded. If the vulcanizing agent is more than 10% by weight, the hardness of the composition is increased, and the crosslinking time is difficult to control. Examples of organic peroxides include 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, p-methyl benzoyl peroxide, t-butyl perbenzoate, o-methyl benzoyl peroxide, dicumyl peroxide , m-methyl benoyl peroxide and benzoyl peroxide. In addition, such an organic peroxide is characterized in that it contains silicon oil alone, or at the same time containing a silicon oil and a fine powder silica-based filler.

EXAMPLE

Although the specific manufacturing method and effect of this invention are shown with reference to an Example, the scope of the present invention is not limited by it. In addition, the characteristics of the thermally conductive silicone rubber composition were measured in the following manner.

[Thermal Conductivity of Silicone Rubber]

Unsteady heat source using silicone rubber thermal conductivity using Hot-disk Method Thermal Analyzer, Model TPA-501 Kyo (commercially available from Kyoto Electronics Manufacturing Co., Ltd.) Measure using the method.

[Hardness of Thermally Conductive Silicone Rubber]

The hardness of the thermally conductive silicone rubber composition was measured using IRHD as detailed in ASTM D 1415.

Example 1

100% by weight of organopolysiloxane gum used as a main component in the organic peroxide-curable millable type thermally conductive silicone rubber composition, 50% by weight of graphite having an average particle size of 10 μm as a thermally conductive filler and organic as a vulcanizing agent. 1% by weight of peroxide 2,5-dimethyl-2,5-di (t-butylperoxy) hexane was blended into a roll, kneaded and homogenized. On the other hand, using a calender roll, the silicone rubber composition was spouted to a thickness of 2 nm, then cured at 160 ° C. for 4 minutes, and after curing for 4 hours at 200 ° C., the volatiles were removed. The properties of the thermally conductive silicone rubber composition are listed in Table 1.

Comparative Example 1

The silicone rubber composition was prepared in the same manner as in Example 1 with 70 wt% of the graphite powder used in Example 1 instead of 50 wt%. The characteristics of the silicone rubber composition are shown in Table 1 below.

Comparative Example 2

The silicone rubber composition was prepared in the same manner as in Example 1 with 100 wt% of the graphite powder used in Example 1 instead of 50 wt%. The characteristics of the silicone rubber composition are shown in Table 1 below.

Comparative Example 3

The silicone rubber composition was prepared in the same manner as in Example 1 with 150 wt% of the graphite powder used in Example 1 instead of 50 wt%. The characteristics of the silicone rubber composition are shown in Table 1 below.

Example 2

100% by weight of organopolysiloxane gum, which is used as a main component in the organic peroxide-curable millable type thermally conductive silicone rubber composition, is a thermally conductive filler containing 0.5 to 500 nm in diameter and several hundred μm in length of carbon nanotube powder. % And 1% by weight of organic peroxide 2,5-dimethyl-2,5-di (t-butylperoxy) hexane as a vulcanizing agent were mixed with a roll, kneaded and homogenized. On the other hand, using a calender roll, the silicone rubber composition was spouted to a thickness of 2 mm, then cured at 160 ° C. for 4 minutes, and after curing for 4 hours at 200 ° C., the volatiles were removed. The properties of the thermally conductive silicone rubber composition are listed in Table 1.

Comparative Example 4

3 wt% of the carbon nanotube powder used in Example 2 was added instead of 1 wt% to prepare a silicone rubber composition in the same manner as in Example 2. The characteristics of the silicone rubber fired product are shown in Table 1 below.

Comparative Example 5

The carbon nanotube powder used in Example 2 was added 5% by weight instead of 1% by weight to prepare a silicone rubber composition in the same manner as in Example 2. The characteristics of the silicone rubber composition are shown in Table 2 below.

Comparative Example 6

The carbon nanotube powder used in Example 2 was added 10% by weight instead of 1% by weight to prepare a silicone rubber composition in the same manner as in Example 2. The characteristics of the silicone rubber composition are shown in Table 1 below.

Example 3

100% by weight of the organopolysiloxane gum used as a main component in the organic peroxide-curable millable type thermally conductive silicone rubber composition, 50% by weight of graphite having an average particle size of 10 μm, and a diameter of 0.5 to 15 nm. 1 weight% of carbon nanotube powders and 1 weight% of organic peroxides 2,5-dimethyl-2,5-di (t-butylperoxy) hexane as a vulcanizing agent were mixed with a roll, and kneaded to homogenize. On the other hand, using a calender roll, the silicone rubber composition was spouted to a thickness of 2 mm, then cured at 160 ° C. for 4 minutes, and after curing for 4 hours at 200 ° C., the volatiles were removed. The properties of the thermally conductive silicone rubber compositions are listed in Table 2.

Comparative Example 7

3 wt% of the carbon nanotube powder used in Example 3 was added instead of 1 wt% to prepare a silicone rubber composition in the same manner as in Example 3. The characteristics of the silicone rubber composition are shown in Table 2 below.

Comparative Example 8

5 wt% of the carbon nanotube powder used in Example 3 was added instead of 1 wt% to prepare a silicone rubber composition in the same manner as in Example 3. The characteristics of the silicone rubber composition are shown in Table 2 below.

Comparative Example 9

The carbon nanotube powder used in Example 3 was added with 10% by weight instead of 1% by weight to prepare a silicone rubber composition in the same manner as in Example 3. The characteristics of the silicone rubber composition are shown in Table 2 below.

Example 4

100% by weight of the organopolysiloxane gum used as a main component in the organic peroxide-curable millable type thermally conductive silicone rubber composition, 70% by weight of graphite having an average particle size of 10 μm and a diameter of 0.5 to 15 nm. 1 weight% of carbon nanotube powders and 1 weight% of organic peroxides 2,5-dimethyl-2,5-di (t-butylperoxy) hexane as a vulcanizing agent were mixed with a roll, and kneaded to homogenize. On the other hand, using a calender roll, the silicone rubber composition was spouted to a thickness of 2 mm, then cured at 160 ° C. for 4 minutes, and after curing for 4 hours at 200 ° C., the volatiles were removed. The properties of the thermally conductive silicone rubber compositions are listed in Table 2.

Comparative Example 10

The carbon nanotube powder used in Example 4 was added 3% by weight instead of 1% by weight to prepare a silicone rubber composition in the same manner as in Example 4. The characteristics of the silicone rubber composition are shown in Table 2 below.

Comparative Example 11

The carbon nanotube powder used in Example 4 was added 5% by weight instead of 1% by weight to prepare a silicone rubber composition in the same manner as in Example 4. The characteristics of the silicone rubber composition are shown in Table 2 below.

Comparative Example 12

The carbon nanotube powder used in Example 4 was added 10% by weight instead of 1% by weight to prepare a silicone rubber composition in the same manner as in Example 4. The characteristics of the silicone rubber composition are shown in Table 2 below.

Example 5

100% by weight of organopolysiloxane gum used as a main component in the organic peroxide-curable millable type thermally conductive silicone rubber composition, 100% by weight of graphite having an average particle size of 10 μm, and a diameter of 0.5 to 15 nm as a thermally conductive filler. 1% by weight of carbon nanotube powder of component (B-3) and 1% by weight of organic peroxide 2,5-dimethyl-2,5-di (t-butylperoxy) hexane as a vulcanizing agent were mixed with a roll and kneaded to homogenize. It was. On the other hand, using a calender roll, the silicone rubber composition was spouted to a thickness of 2 mm, then cured at 160 ° C. for 4 minutes, and after curing for 4 hours at 200 ° C., the volatiles were removed. The properties of the thermally conductive silicone rubber compositions are listed in Table 3.

Comparative Example 13

3 wt% of the carbon nanotube powder used in Example 5 was added instead of 1 wt% to prepare a silicone rubber composition in the same manner as in Example 5. The characteristics of the silicone rubber composition are shown in Table 3 below.

Comparative Example 14

The carbon nanotube powder used in Example 5 was added 5% by weight instead of 1% by weight to prepare a silicone rubber composition in the same manner as in Example 5. The characteristics of the silicone rubber composition are shown in Table 3 below.

Comparative Example 15

The carbon nanotube powder used in Example 5 was added to 10% by weight instead of 1% by weight to prepare a silicone rubber composition in the same manner as in Example 5. The characteristics of the silicone rubber composition are shown in Table 3 below.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Thermal Conductivity (W / m.K) 3.0 1.0 4.2 5.5 7.3 2.0 3.9 5.2 Hardness 45 42 50 58 71 46 53 65

Example 3 Example 4 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 Thermal Conductivity (W / m.K) 4.5 5.7 5.9 10.3 14.8 7.3 12.1 16.8 Hardness 50 54 55 65 78 61 72 84

Example 5 Comparative Example 13 Comparative Example 14 Comparative Example 15 Thermal Conductivity (W / m.K) 7.8 9.8 13.3 19.4 Hardness 65 72 81 88

As a result, when the thermally conductive filler is used as a single powder, the effect of thermal conductivity can be maximized when a mixed powder of graphite and carbon nanotubes is used. In order to maximize the effect of thermal conductivity, it is preferable to use 3% by weight or more of carbon nanotube powder in a constant graphite content.

As described above, when the CNT (carbone nanotube) used in the present invention is added as a thermally conductive additive, the thermal conductivity is greatly improved even with a small amount compared to the conventionally added amount of the thermally conductive material. It greatly contributes to the improvement of moldability and thermal conductivity.

Claims (4)

A thermally conductive silicone rubber composition comprising an organic peroxide-curable organopolysiloxane gum, a thermally conductive filler, an organic peroxide vulcanizing agent. The organopolysiloxane gum according to claim 1, wherein the organopolysiloxane gum comprises a dimethyl group, methylphenyl group, methylvinyl group, or fluorine group. The thermally conductive silicone rubber composition according to claim 1, wherein the thermally conductive filler comprises natural phosphate graphite, artificial phosphate graphite, or carbon nanotubes alone or in a mixed powder of 1 to 800 wt% per 100 wt% of organopolysiloxane. The thermally conductive silicone rubber according to claim 1, wherein the organic peroxide, wherein the vulcanizing agent is 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, comprises 0.1 to 10% by weight per 100% by weight of the organopolysiloxane. Composition.