CN105566918A - Silicon sheet and preparation method thereof - Google Patents

Abstract

The invention relates to a silica gel sheet. The silica gel sheet contains thermally conductive powder. Based on the total weight of the silica gel sheet, the content of the thermally conductive powder is 90-97% by weight. The present invention also relates to a method for preparing a silica gel sheet. The method comprises: (1) mixing vinyl silicone oil, hydrogen-containing silicone oil, an inhibitor, and a catalyst to obtain an organosilicon crosslinking system; (2) mixing heat-conducting powder, organosilicon Ball milling the cross-linking system and an organic solvent; (3) Spray granulating the mixture obtained by the ball milling to obtain a powder; (4) Dry pressing the powder; (5) Exchanging the sheet obtained by the dry pressing joint reaction. The present invention also relates to the silica gel sheet prepared by the above method. The silica gel sheet of the invention has the advantages of simple preparation process, excellent thermal conductivity, low production cost, etc., and can meet the heat dissipation requirements of electronic product modules.

Description

A kind of silica gel sheet and preparation method thereof

technical field

The invention relates to a silica gel sheet, a method for preparing the silica gel sheet, and the silica gel sheet prepared by the method.

Background technique

With the rapid development of industries such as aviation, automobiles, and electronics, people's requirements for thermally conductive materials are getting higher and higher. Silicone has become an excellent carrier for thermally conductive composite materials because of its excellent heat resistance, insulation, and weather resistance. However, the thermal conductivity of organic silicon composite materials is poor at present, and a coupling agent needs to be added in the preparation process. The preparation process is complicated and the cost is high, which seriously affects the application of organic silicon thermal conductive materials.

Therefore, there is an urgent need for a silicone thermally conductive material with simple preparation process, excellent thermal conductivity and low production cost.

Contents of the invention

The purpose of the present invention is to overcome the defects of complex preparation process, poor thermal conductivity and high production cost in organic silicon heat-conducting materials in the prior art, to provide a silica gel sheet, a method for preparing a silica gel sheet, and the silica gel prepared by the method piece.

The inventors of the present invention found in research that when the thermal conductivity of the silica gel sheet is above 6W/mK, the thermal conductivity of the silica gel sheet can be significantly improved, the production cost is low, and the preparation process of the silica gel sheet is relatively simple.

Therefore, in order to achieve the above object, on the one hand, the present invention provides a silica gel sheet, the thermal conductivity of the silica gel sheet is above 6W/mK.

On the other hand, the present invention also provides a kind of preparation method of silica gel sheet, and this method comprises:

(1) Mix vinyl silicone oil, hydrogen-containing silicone oil, inhibitor, and catalyst to obtain a silicone crosslinking system;

(2) Ball milling the heat-conducting powder, the organosilicon cross-linking system and the organic solvent;

(3) The mixture obtained by ball milling is sprayed and granulated to obtain a powder;

(4) Carry out dry pressing molding to powder;

(5) Perform a crosslinking reaction on the sheet obtained by dry pressing.

In the third aspect, the present invention also provides the silica gel sheet prepared by the above method.

The silica gel sheet of the invention has the advantages of simple preparation process, excellent thermal conductivity, low production cost, etc., and can meet the heat dissipation requirements of electronic product modules.

Other features and advantages of the present invention will be described in detail in the detailed description that follows.

detailed description

Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

The invention provides a silica gel sheet, the thermal conductivity of the silica gel sheet is above 6W/mK.

Preferably, the thermal conductivity of the silica gel sheet is 6-6.8W/mK.

According to the silica gel sheet of the present invention, as long as the thermal conductivity of the silica gel sheet is more than 6W/mK, the thermal conductivity of the silica gel sheet can be improved, but in order to further improve the thermal conductivity of the silica gel sheet, the silica gel sheet contains thermally conductive powder. Based on the total weight of the silica gel sheet, the content of the thermally conductive powder is 90-97% by weight.

According to the silica gel sheet of the present invention, the thermally conductive powder in the silica gel sheet can be a conventional thermally conductive powder in the art, preferably at least one selected from aluminum oxide, zinc oxide, silicon dioxide, aluminum nitride, boron nitride and silicon carbide. One, more preferably aluminum oxide and/or zinc oxide, can further increase the thermal conductivity of the silica gel sheet, thereby further improving the thermal conductivity of the silica gel sheet. When the heat-conducting powder is a mixture of aluminum oxide and zinc oxide, the weight ratio of aluminum oxide and zinc oxide is preferably 1:0.2-1.

According to the silica gel sheet of the present invention, wherein, the size of the heat-conducting powder can be the specification of the heat-conducting powder conventionally used in the art to prepare the heat-conducting silica gel sheet, but, in order to further improve the thermal conductivity of the silica gel sheet, preferably, the particle size of the heat-conducting powder The diameter is 0.5-4.5μm.

On the other hand, the present invention also provides a kind of preparation method of silica gel sheet, and this method comprises:

(1) Mix vinyl silicone oil, hydrogen-containing silicone oil, inhibitor, and catalyst to obtain a silicone crosslinking system;

(2) Ball milling the heat-conducting powder, the organosilicon cross-linking system and the organic solvent;

(3) The mixture obtained by ball milling is sprayed and granulated to obtain a powder;

(4) Carry out dry pressing molding to powder;

(5) Perform a crosslinking reaction on the sheet obtained by dry pressing.

According to the method of the present invention, wherein, as long as the above-mentioned method is used to prepare the silica gel sheet, the thermal conductivity of the obtained silica gel sheet can be improved, but in order to further improve the thermal conductivity of the prepared silica gel sheet, preferably, the thermal conductivity The powder is selected from at least one of aluminum oxide, zinc oxide, silicon dioxide, aluminum nitride, boron nitride and silicon carbide, more preferably aluminum oxide and/or zinc oxide, which can further improve the thermal conductivity of the silica gel sheet, thereby Further improve the thermal conductivity of the silica gel sheet. When the heat-conducting powder is a mixture of aluminum oxide and zinc oxide, the weight ratio of aluminum oxide and zinc oxide is preferably 1:0.2-1.

According to the method of the present invention, wherein, the size of the heat-conducting powder can be the specification of the heat-conducting powder conventionally used in the art to prepare the heat-conducting silica gel sheet, but, in order to further improve the thermal conductivity of the prepared silica gel sheet, preferably, the heat-conducting powder The particle size is 0.5-4.5μm.

According to the method of the present invention, wherein, in step (5), the conditions of the crosslinking reaction can be the conditions of the conventional crosslinking reaction in the art, but, in order to further improve the thermal conductivity of the prepared silica gel sheet, preferably, The conditions of the crosslinking reaction include: the temperature is 130-180° C., and the time is 15-60 minutes.

According to the method of the present invention, wherein, in step (1), the amount ratio between vinyl silicone oil, hydrogen-containing silicone oil, inhibitor and catalyst can be the conventional amount ratio in this field, for example, vinyl silicone oil, hydrogen-containing silicone oil The weight ratio of the inhibitor and the catalyst can be 100:7-15:0.02-0.1:0.02-0.1.

According to the method of the present invention, wherein, in step (2), the amount ratio between the heat-conducting powder, the organosilicon crosslinking system and the organic solvent can be a conventional amount ratio in the field, for example, the heat-conducting powder, the organosilicon crosslinking system The weight ratio with the organic solvent can be 100:3-6:200-500.

In the present invention, the organic solvent may be a conventional organic solvent in the art, for example, at least one selected from n-hexane, acetone, xylene and toluene.

In the present invention, the ball milling method and conditions can adopt conventional ball milling methods and conditions in the art, for example, the ball milling conditions can include: ball milling in a ball mill jar for 2-4 hours.

According to the method of the present invention, wherein, in step (3), the spray granulation conditions can be conventional spray granulation conditions in the art, preferably, the spray granulation conditions include: the temperature is 70-100°C. When the temperature is within this range, the mixture obtained by ball milling can be prevented from cross-linking reaction during the spray granulation process. Wherein, the spray granulation method can be a conventional spray granulation method in the art.

According to the method of the present invention, wherein, in step (4), the conditions of dry pressing can be conventional dry pressing conditions in the art, for example, the conditions of dry pressing can include: the pressure is 8-80 MPa. Wherein, the method of dry pressing may be a conventional dry pressing method in the art.

According to the method of the present invention, wherein the vinyl silicone oil can be the vinyl silicone oil used in the art for preparing silica gel sheets, for example, it can be vinyl-terminated silicone oil. In the present invention, the viscosity and vinyl content of vinyl silicone oil are not particularly limited, for example, its viscosity can be 100-50000cp, based on the moles of vinyl silicone oil, the content of vinyl in the vinyl silicone oil is 0.2 -2mol%. According to the method of the present invention, wherein the hydrogen-containing silicone oil can be the hydrogen-containing silicone oil commonly used in the art to prepare silica gel sheets, for example, it can be hydrogen-terminated silicone oil. In the present invention, the content of SiH in the hydrogen-containing silicone oil is not particularly limited, for example, the content of SiH in the hydrogen-containing silicone oil may be 0.05-0.5% by weight.

According to the method of the present invention, wherein, the inhibitor can be a conventional inhibitor in the art that prevents the crosslinking reaction from occurring, for example, it can be selected from 3-methyl-1-butyn-3-ol, 1-ethynyl At least one of cyclohexanol, methylhydrazine, phenylhydrazine, triphenylphosphine, triphenylphosphite, and sulfoxides.

According to the method of the present invention, wherein, the catalyst can be a conventional catalyst used in the art to catalyze the crosslinking reaction of vinyl silicone oil and hydrogen-containing silicone oil, and the catalyst is preferably a Group VIII transition metal and its compound or complex , more preferably a platinum catalyst, more preferably at least one of chloroplatinic acid-isopropanol, chloroplatinic acid-divinyl tetramethyldisiloxane and chloroplatinic acid-diethyl phthalate .

In the third aspect, the present invention also provides the silica gel sheet prepared by the above method.

The filling amount of thermal conductive powder in the silica gel sheet of the present invention is as high as 90-97% by weight, and the thermal conductivity can reach more than 6W/mK. Therefore, the silica gel sheet of the present invention has excellent thermal conductivity.

Example

Example 1

This example is used to illustrate the silica gel sheet of the present invention and its preparation method.

(1) Vinyl silicone oil (viscosity is 100cp, vinyl content is 0.2mol%), hydrogen-containing silicone oil (SiH content is 0.05% by weight), 1-ethynyl cyclohexanol, chloroplatinic acid-divinyl tetra Methyldisiloxane is mixed uniformly according to the weight ratio of 100:7:0.06:0.02 to obtain a silicone crosslinking system;

(2) Ball mill aluminum oxide (with a particle size of 4.5 μm), silicone crosslinking system and n-hexane for 3 hours at a weight ratio of 100:3:200;

(3) performing spray granulation on the mixture obtained by ball milling at 80° C. to obtain a powder;

(4) Dry pressing the powder under the condition of 8MPa to obtain a sheet with a thickness of 2mm;

(5) The sheet obtained by dry pressing was subjected to a crosslinking reaction at 180° C. for 15 minutes to obtain a silica gel sheet A1.

Example 2

This example is used to illustrate the silica gel sheet of the present invention and its preparation method.

(1) Vinyl silicone oil (viscosity is 20000cp, vinyl content is 2mol%), hydrogen-containing silicone oil (SiH content is 0.5% by weight), triphenylphosphine, chloroplatinic acid-isopropanol according to the weight ratio of 100: 11:0.06:0.02 to mix evenly to obtain a silicone cross-linking system;

(2) Ball mill zinc oxide (with a particle size of 4.5 μm), silicone crosslinking system and n-hexane for 2 hours at a weight ratio of 100:3.5:400;

(3) The mixture obtained by ball milling is subjected to spray granulation at 85° C. to obtain a powder;

(4) Dry pressing the powder under the condition of 40MPa to obtain a sheet with a thickness of 2mm;

(5) The sheet obtained by dry pressing was subjected to crosslinking reaction at 150°C for 60 minutes to obtain silica gel sheet A2. The filling amount of zinc oxide in the prepared silica gel sheet was calculated according to the mass of the residual components after spraying. The results are shown in the table 1.

Example 3

This example is used to illustrate the silica gel sheet of the present invention and its preparation method.

(1) Vinyl silicone oil (viscosity is 50000cp, vinyl content is 1.5mol%), hydrogen-containing silicone oil (the content of SiH is 0.25% by weight), phenylhydrazine, chloroplatinic acid-diethyl phthalate Mix evenly at a ratio of 100:15:0.02:0.1 to obtain a silicone crosslinking system;

(2) Ball mill the mixture of alumina and zinc oxide (the weight ratio of alumina and zinc oxide is 3:1, and the particle size is 0.5 μm), the silicone crosslinking system and n-hexane according to the weight ratio of 100:5:500 4h;

(3) Spray granulating the mixture obtained by ball milling at 100° C. to obtain a powder;

(4) Dry pressing the powder under the condition of 50MPa to obtain a sheet with a thickness of 2mm;

(5) The sheet obtained by dry pressing was subjected to a cross-linking reaction at 130° C. for 30 minutes to obtain a silica gel sheet A3.

Example 4

This example is used to illustrate the silica gel sheet of the present invention and its preparation method.

A silica gel sheet was prepared according to the method in Example 1, except that boron nitride with the same particle size was used instead of alumina with the same particle size to obtain a silica gel sheet A4.

Example 5

This example is used to illustrate the silica gel sheet of the present invention and its preparation method.

A silica gel sheet was prepared according to the method of Example 1, except that the alumina with a particle size of 4.5 μm was replaced with alumina with a particle size of 10 μm to obtain a silica gel sheet A5.

Comparative example 1

Prepare glue A and glue B first, wherein the component content of glue A is: 50 parts of vinyl silicone oil, 7 parts of hydrogen, 0.06 parts of cyclohexanol: 210.5 parts of alumina powder; the content of components of glue B is: 50 parts Part of vinyl silicone oil, 0.02 part of chloroplatinic acid-divinyltetramethyldisiloxane, 217.5 parts of alumina powder, the preparation of glue A and glue B can be prepared as long as its components are mixed, and then A Glue and B glue were mixed according to the weight ratio of 1:1, and stirred for 0.5h to obtain a slurry, and then the slurry was calendered, and then cross-linked at 120°C for 0.5h to obtain the same thickness as in Example 1 Silicone sheet D1.

test case

The filling amount of the thermally conductive powder of the silica gel sheets A1-A5 prepared in Examples 1-5 and the silica gel sheet D1 prepared in Comparative Example 1 was determined by thermogravimetric method. The specific method is: weigh the silica gel sheet, then raise the temperature from 25°C to 800°C at a rate of 5°C/min in the air atmosphere, and the remaining solid obtained when the temperature rises to 800°C is the thermal conductive powder filled in the silica gel sheet, and then Weigh the remaining solids to calculate the filling amount of the thermally conductive powder.

The silica gel sheet A1-A5 that embodiment 1-5 makes and the silica gel sheet D1 that comparative example 1 makes carry out thermal conductivity test, and the method for thermal conductivity test is laser flash method, and equipment is laser thermal conductivity meter, model is NETZSCHLFA447, test The results are shown in Table 1.

Table 1

Sample serial number Filling amount (weight%) Thermal conductivity (W/mK) A1 97.1 6.8 A2 96.6 6.8 A3 95.2 6.7 A4 90.9 6.1 A5 90.1 6 D1 80 1.5

Comparing Examples 1-5 with Comparative Example 1, it can be seen that the filling amount of heat-conducting powder in the silica gel sheet of the present invention is as high as 90-97% by weight, and the thermal conductivity can reach more than 6W/mK. Therefore, the silica gel sheet of the present invention has Excellent thermal conductivity.

Comparing Example 1 with Example 4, it can be seen that when the thermally conductive powder is aluminum oxide and/or zinc oxide, the thermal conductivity of the prepared silica gel sheet can be further improved.

Comparing Example 1 with Example 5, it can be seen that when the particle size of the thermally conductive powder is 0.5-4.5 μm, the thermal conductivity of the prepared silica gel sheet can be further improved, that is, the use of a smaller particle size conductive powder can further improve The thermal conductivity of the prepared silica gel sheets.

The silica gel sheet of the invention has the advantages of simple preparation process, excellent thermal conductivity, low production cost, etc., and can meet the heat dissipation requirements of electronic product modules.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention. These simple modifications All belong to the protection scope of the present invention.

In addition, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way if there is no contradiction. The combination method will not be described separately.

In addition, various combinations of different embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the idea of the present invention, they should also be regarded as the disclosed content of the present invention.

Claims (17)

1. A silica gel sheet, characterized in that the thermal conductivity of the silica gel sheet is more than 6W/mK. 2. The silica gel sheet according to claim 1, wherein the silica gel sheet contains thermally conductive powder, based on the total weight of the silica gel sheet, the content of the thermally conductive powder is 90-97% by weight. 3. The silica gel sheet according to claim 2, wherein the thermally conductive powder is selected from at least one of aluminum oxide, zinc oxide, silicon dioxide, aluminum nitride, boron nitride and silicon carbide, preferably aluminum oxide and/or zinc oxide. 4. The silica gel sheet according to claim 2 or 3, wherein the particle size of the heat-conducting powder is 0.5-4.5 μm. 5. a preparation method of silica gel sheet, it is characterized in that, the method comprises: (1) Mix vinyl silicone oil, hydrogen-containing silicone oil, inhibitor, and catalyst to obtain a silicone crosslinking system; (2) Ball milling the heat-conducting powder, the organosilicon cross-linking system and the organic solvent; (3) The mixture obtained by ball milling is sprayed and granulated to obtain a powder; (4) Carry out dry pressing molding to powder; (5) Perform a crosslinking reaction on the sheet obtained by dry pressing. 6 . The method according to claim 5 , wherein, in step (5), the conditions of the crosslinking reaction include: the temperature is 130-180° C., and the time is 15-60 min. 7. The method according to claim 5, wherein the thermally conductive powder is selected from at least one of aluminum oxide, zinc oxide, silicon dioxide, aluminum nitride, boron nitride and silicon carbide, preferably aluminum oxide and / or zinc oxide. 8. The method according to claim 5 or 7, wherein the particle size of the thermally conductive powder is 0.5-4.5 μm. 9. The method according to claim 5, wherein, in step (1), the weight ratio of vinyl silicone oil, hydrogen-containing silicone oil, inhibitor, and catalyst is 100:7-15:0.02-0.1:0.02-0.1. 10. The method according to claim 5, wherein, in step (2), the weight ratio of the heat-conducting powder, the silicone cross-linking system and the organic solvent is 100:3-6:200-500. 11. The method according to claim 5, wherein, in step (3), the conditions for spray granulation include: a temperature of 70-100°C. 12. The method according to claim 5, wherein, in step (4), the conditions for dry pressing include: the pressure is 8-80 MPa. 13. The method according to claim 5 or 9, wherein the viscosity of the vinyl silicone oil is 100-50000cp, based on the number of moles of the vinyl silicone oil, the content of vinyl in the vinyl silicone oil is 0.2- 2mol%. 14. The method according to claim 5 or 9, wherein, based on the total weight of the hydrogen-containing silicone oil, the content of SiH in the hydrogen-containing silicone oil is 0.05-0.5% by weight. 15. The method according to claim 5 or 9, wherein the inhibitor is selected from the group consisting of 3-methyl-1-butyn-3-ol, 1-ethynylcyclohexanol, methylhydrazine, phenylhydrazine, tris At least one of phenylphosphine, triphenyl phosphite, and sulfoxides. 16. The method according to claim 5 or 9, wherein the catalyst is a Group VIII transition metal and a compound or complex thereof, preferably a platinum catalyst, more preferably chloroplatinic acid-isopropanol, platinum chloride At least one of acid-divinyltetramethyldisiloxane and chloroplatinic acid-diethylphthalate. 17. The silica gel sheet prepared by the method according to any one of claims 5-16.