A low-contact thermal resistance thermally conductive silicone cloth and its preparation method

Abstract

This invention discloses a low-contact thermal resistance thermally conductive silicone cloth. The raw materials, by weight, include: 15-50 parts modified polysiloxane, 120-550 parts inorganic powder, 0.1-0.5 parts lubricant, and 0.2-45 parts diluent. The thermally conductive powder prepared by the combined action of alumina with different shapes and particle sizes exhibits low contact thermal resistance and high thermal conductivity. High thermal conductivity can be achieved with low amounts of the added thermally conductive powder. Furthermore, the coating process results in low viscosity before molding, high filler uniformity, easy processing, and good surface smoothness, thickness tolerance, and product uniformity. It also possesses high reliability, insulation, softness and elasticity, low contact thermal resistance, and high thermal conductivity, making it widely applicable in switching power supplies, communication equipment, computers, flat-panel TVs, mobile devices, video equipment, network products, and home appliances.

Description

Technical Field

[0001] This invention relates to a low-contact thermal resistance thermally conductive silicone cloth and its preparation method, specifically to C08L, and more particularly to the field of polymer compound compositions. Background Technology

[0002] With the development of technology, the functional requirements of electronic products are increasing, and the integration of these functions is also growing. This leads to higher heat dissipation during operation. If the generated heat cannot be dissipated in time, it can cause internal damage to the electronic product and affect its lifespan. Current heat dissipation methods mostly involve adding heat sinks to conduct heat away. However, the interface between the electronic product and the heat sink still presents a certain degree of heat dissipation resistance. Therefore, developing a bonding material with good heat dissipation performance is crucial for highly integrated electronic products. Current heat dissipation bonding materials mostly optimize the particle size of heat dissipation powders. Nanoscale heat dissipation powders have good heat dissipation effects and high thermal conductivity. However, nanoscale heat dissipation powders are prone to agglomeration, which increases the consistency of the bonding material, making construction more difficult and resulting in higher production costs.

[0003] Chinese invention patent CN201610119396.0 discloses a thermally conductive composite material and a thermally conductive sheet made from the material, as well as a method for preparing the same. It optimizes the selection of particle size and morphology of various thermally conductive fillers and balances surface wettability treatment to achieve excellent thermal conductivity while maintaining the material's safety, resilience, and flexibility. However, it requires the combined action of multiple fillers, some of which contain metal powder, reducing the material's insulation performance. Chinese invention patent CN201310408997.X discloses a method for preparing an insulating and highly thermally conductive composite material. It uses specific types and particle sizes of inorganic particles as composite thermally conductive fillers, added to a crystalline polymer matrix to form a composite material with more thermal conductivity pathways than a single filler, significantly improving the material's thermal conductivity. However, the resulting composite material has high hardness, limiting its application range. Summary of the Invention

[0004] In order to reduce the contact thermal resistance of silicone cloth and improve its insulation performance, the first aspect of the present invention provides a low contact thermal resistance thermally conductive silicone cloth, the raw materials for which, by weight, include: 15-50 parts of modified polysiloxane, 120-550 parts of inorganic powder, 0.1-0.5 parts of lubricant, and 0.2-45 parts of diluent.

[0005] In a preferred embodiment, the modified polysiloxane is selected from one or a combination of several of double-bond modified polysiloxanes or hydrogenated modified polysiloxanes.

[0006] In a preferred embodiment, the modified polysiloxane has a viscosity of 30-550000 mPa·s at 25°C.

[0007] In a preferred embodiment, the modified polysiloxane has a viscosity of 40-350000 mPa·s at 25°C.

[0008] In a preferred embodiment, the inorganic powder is selected from one or a combination of several of the following: metal oxides, metal nitrides, non-metal oxides, non-metal carbides, and non-metal nitrides.

[0009] In a preferred embodiment, the particle size of the metal oxide is 0.05-90 μm, and the particle size of the non-metal nitride is 3-15 μm.

[0010] In a preferred embodiment, the inorganic powder is a combination of metal oxides and non-metal nitrides, wherein the weight ratio of the metal oxides to the non-metal nitrides is (145-165):10.

[0011] In a preferred embodiment, the metal oxide is selected from one or a combination of aluminum oxide, zinc oxide, and magnesium oxide.

[0012] In a preferred embodiment, the non-metallic nitride is selected from one or a combination of silicon nitride and boron nitride.

[0013] In a preferred embodiment, the inorganic powder is a combination of alumina and boron nitride.

[0014] In a preferred embodiment, the alumina is a combination of spherical alumina and ellipsoidal alumina.

[0015] In a preferred embodiment, the spherical alumina has a particle size of 3-10 μm, and the ellipsoidal alumina has a particle size of 0.1-1 μm.

[0016] In a preferred embodiment, the alumina is a combination of spherical alumina with a particle size of 5-10 μm, spherical alumina with a particle size of 3-5 μm, and ellipsoidal alumina with a particle size of 0.1-1 μm.

[0017] In a preferred embodiment, the alumina is a combination of spherical alumina with a particle size of 10 μm, spherical alumina with a particle size of 3 μm, and ellipsoidal alumina with a particle size of 0.5 μm.

[0018] In a preferred embodiment, the weight ratio of the spherical alumina with a particle size of 10 μm, the spherical alumina with a particle size of 3 μm, and the ellipsoidal alumina with a particle size of 0.5 μm is (90-100):(30-50):(10-25).

[0019] In a preferred embodiment, the boron nitride has a particle size of 5-10 μm.

[0020] In a preferred embodiment, the diluent is selected from one or a combination of several of the following: n-hexane, methanol, n-butane, toluene, xylene, cyclohexanone, isopropanol, isoparaffins, acetone, and butanol.

[0021] In a preferred embodiment, the diluent is acetone.

[0022] In a preferred embodiment, the lubricating agent is selected from one or a combination of several of the following: siloxane lubricants, aluminate esters, acrylate esters, and alcohol esters.

[0023] In a preferred embodiment, the lubricant is a siloxane lubricant, which is an alkylsiloxane selected from octyltriethoxysilane coupling agent, dodecyltrimethoxysilane coupling agent, and hexadecyltrimethoxysilane coupling agent.

[0024] A second aspect of the present invention provides a method for preparing a low-contact thermal resistance thermally conductive silicone cloth, comprising the following steps:

[0025] (1) Vacuum dry the inorganic powder and then cool it naturally to room temperature;

[0026] (2) Add modified polysiloxane and lubricant to the dried inorganic powder, mix evenly, add diluent, stir evenly, and degas to obtain mixed adhesive.

[0027] (3) Apply the mixed adhesive to the base film, use a coating scraper to spread it evenly, dry it in the drying tunnel, cut it, and rewind it into a roll once to obtain the final product.

[0028] In a preferred embodiment, the vacuum drying temperature in step 1 is 170-200℃, and the drying time is 3-5 hours.

[0029] In a preferred embodiment, the degassing pressure in step 2 is -1 to 1 mPa, and the degassing time is 20 to 30 min.

[0030] In a preferred embodiment, the drying tunnel temperature in step 3 is 150-180℃, the drying tunnel length is 10-15m, and the drying tunnel speed is 1-5m / min.

[0031] In a preferred embodiment, the coating thickness in step 3 is 0.01-0.2 mm.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The low contact thermal resistance thermal conductive silicone cloth of the present invention is prepared by the combined action of alumina with different shapes and particle sizes. The thermal conductive powder has low contact thermal resistance and high thermal conductivity. High thermal conductivity can be achieved by using a low amount of thermal conductive powder.

[0034] (2) The low contact thermal resistance thermal conductive silicone cloth of the present invention adopts a coating process, with low viscosity before molding, high uniformity of filler mixing, easy processing, and good surface flatness, thickness tolerance and product uniformity of the produced product.

[0035] (3) The low contact thermal resistance thermal conductive silicone cloth of the present invention has high reliability, insulation, softness and elasticity, low contact thermal resistance and high thermal conductivity, and can be widely used in switching power supplies, communication equipment, computers, flat panel TVs, mobile devices, video equipment, network products, home appliances and other fields. Detailed Implementation

[0036] Example 1

[0037] A low-contact thermal resistance thermally conductive silicone cloth is prepared by means of the following raw materials in parts by weight: 15 parts modified polysiloxane, 160 parts inorganic powder, 0.3 parts lubricant, and 7 parts diluent.

[0038] The modified polysiloxane is a vinyl-modified polysiloxane with a vinyl content of 0.18 wt% and a viscosity of 2500 mPa·s at 25°C. It was purchased from Shenzhen Jipeng Silicon Fluorine Materials Co., Ltd., and its grade is JP-01V-2500.

[0039] The inorganic powder is a combination of alumina and boron nitride; the alumina is a combination of spherical alumina with a particle size of 10 μm (Sichuan Ya'an Baitu New Materials, Bak-10), spherical alumina with a particle size of 3 μm (Zhonglv New Materials, ASF-3), and ellipsoidal alumina with a particle size of 0.5 μm (Sichuan Ya'an Baitu New Materials, SHA-10); the boron nitride has a particle size of 5 μm (Sichuan Ya'an Baitu New Materials, PBN-5); the weight ratio of spherical alumina with a particle size of 10 μm, spherical alumina with a particle size of 3 μm, ellipsoidal alumina with a particle size of 0.5 μm and boron nitride is 90:40:20:10.

[0040] The diluent is acetone. The lubricant is octyltriethoxysilane coupling agent.

[0041] A method for preparing a low-contact thermal resistance thermally conductive silicone cloth includes the following steps:

[0042] (1) Vacuum dry the inorganic powder and then cool it naturally to room temperature;

[0043] (2) Add modified polysiloxane and lubricant to the dried inorganic powder, mix evenly, add diluent, stir evenly, and degas to obtain mixed adhesive.

[0044] (3) Apply the mixed adhesive to the base film, use a coating scraper to spread it evenly, dry it in the drying tunnel, cut it, and rewind it into a roll once to obtain the final product.

[0045] The vacuum drying temperature in step 1 is 180℃, and the drying time is 4 hours.

[0046] The degassing pressure in step 2 is -1 mPa, and the degassing time is 30 min.

[0047] The drying tunnel temperature in step 3 is 160℃, the tunnel length is 12m, and the drying speed is 5m / min. The coating thickness in step 3 is 0.03mm. The base film is a PI film.

[0048] Example 2

[0049] A low-contact thermal resistance thermally conductive silicone cloth is prepared by means of the following raw materials in parts by weight: 16 parts modified polysiloxane, 170 parts inorganic powder, 0.4 parts lubricant, and 10 parts diluent.

[0050] The modified polysiloxane is a vinyl-modified polysiloxane with a vinyl content of 0.28 wt% and a viscosity of 1500 mPa·s at 25°C. It was purchased from Shenzhen Jipeng Silicon Fluorine Materials Co., Ltd., and its grade is JP-01V-1500.

[0051] The inorganic powder is a combination of alumina and boron nitride; the alumina is a combination of spherical alumina with a particle size of 10 μm (Sichuan Ya'an Baitu New Materials, Bak-10), spherical alumina with a particle size of 3 μm (Sichuan Ya'an Baitu New Materials, Bak-3), and ellipsoidal alumina with a particle size of 0.5 μm (Sichuan Ya'an Baitu New Materials, Bak-S05); the boron nitride has a particle size of 10 μm (Sichuan Ya'an Baitu New Materials, PBN-10); the weight ratio of spherical alumina with a particle size of 10 μm, spherical alumina with a particle size of 3 μm, ellipsoidal alumina with a particle size of 0.5 μm and boron nitride is 100:40:20:10.

[0052] The diluent is acetone. The lubricant is dodecyltrimethoxysilane coupling agent.

[0053] A method for preparing a low-contact thermal resistance thermally conductive silicone cloth includes the following steps:

[0054] (1) Vacuum dry the inorganic powder and then cool it naturally to room temperature;

[0055] (2) Add modified polysiloxane and lubricant to the dried inorganic powder, mix evenly, add diluent, stir evenly, and degas to obtain mixed adhesive.

[0056] (3) Apply the mixed adhesive to the base film, use a coating scraper to spread it evenly, dry it in the drying tunnel, cut it, and rewind it into a roll once to obtain the final product.

[0057] The vacuum drying temperature in step 1 is 180℃, and the drying time is 4 hours.

[0058] The degassing pressure in step 2 is -1 mPa, and the degassing time is 30 min.

[0059] The drying tunnel temperature in step 3 is 170℃, the tunnel length is 12m, and the drying speed is 4m / min. The coating thickness in step 3 is 0.04mm. The base film is a PI film.

[0060] Comparative Example 1

[0061] A low-contact thermal resistance thermally conductive silicone cloth is prepared by means of the following raw materials in parts by weight: 15 parts modified polysiloxane, 150 parts inorganic powder, 0.3 parts lubricant, and 5 parts diluent.

[0062] The modified polysiloxane is a vinyl-modified polysiloxane with a vinyl content of 0.32 wt% and a viscosity of 1000 mPa·s at 25°C. It was purchased from Shenzhen Jipeng Silicon Fluorine Materials Co., Ltd., and its grade is JP-01V-1000.

[0063] The inorganic powder is a combination of alumina and boron nitride; the alumina is a combination of spherical alumina with a particle size of 10 μm (Sichuan Ya'an Baitu New Materials, Bak-10), spherical alumina with a particle size of 3 μm (Sichuan Ya'an Baitu New Materials, Bak-3), and ellipsoidal alumina with a particle size of 0.5 μm (Sichuan Ya'an Baitu New Materials, Bak-05); the boron nitride has a particle size of 5 μm (Sichuan Ya'an Baitu New Materials, PBN-5); the weight ratio of spherical alumina with a particle size of 10 μm, spherical alumina with a particle size of 3 μm, ellipsoidal alumina with a particle size of 0.5 μm and boron nitride is 80:40:20:10.

[0064] The diluent is acetone. The lubricant is a hexadecyltrimethoxysilane coupling agent.

[0065] A method for preparing a low-contact thermal resistance thermally conductive silicone cloth includes the following steps:

[0066] (1) Vacuum dry the inorganic powder and then cool it naturally to room temperature;

[0067] (2) Add modified polysiloxane and lubricant to the dried inorganic powder, mix evenly, add diluent, stir evenly, and degas to obtain mixed adhesive.

[0068] (3) Apply the mixed adhesive to the base film, use a coating scraper to spread it evenly, dry it in the drying tunnel, cut it, and rewind it into a roll once to obtain the final product.

[0069] The vacuum drying temperature in step 1 is 180℃, and the drying time is 4 hours.

[0070] The degassing pressure in step 2 is -1 mPa, and the degassing time is 30 min.

[0071] The drying tunnel temperature in step 3 is 160℃, the tunnel length is 12m, and the drying speed is 5m / min. The coating thickness in step 3 is 0.07mm. The base film is a PI film.

[0072] Comparative Example 2: A low-contact thermal resistance thermally conductive silicone cloth, the raw materials for which are prepared by weight include: 13 parts modified polysiloxane, 180 parts inorganic powder, 0.3 parts lubricant, and 2 parts diluent.

[0073] The modified polysiloxane is a vinyl-modified polysiloxane with a vinyl content of 0.17 wt% and a viscosity of 3000 mPa·s at 25°C. It was purchased from Shenzhen Jipeng Silicon Fluorine Materials Co., Ltd., and its grade is JP-01V-3000.

[0074] The inorganic powder is a combination of alumina; the alumina is a combination of spherical alumina with a particle size of 10μm (Sichuan Ya'an Baitu New Materials, SHA-10), spherical alumina with a particle size of 3μm (Sichuan Ya'an Baitu New Materials, Bak-3), and ellipsoidal alumina with a particle size of 0.5μm (Sichuan Ya'an Baitu New Materials, Bak-05), and the weight ratio of spherical alumina with a particle size of 10μm, spherical alumina with a particle size of 3μm, and ellipsoidal alumina with a particle size of 0.5μm is 110:50:20.

[0075] The diluent is isododecane. The lubricant is stearic acid.

[0076] A method for preparing a low-contact thermal resistance thermally conductive silicone cloth includes the following steps:

[0077] (1) Vacuum dry the inorganic powder and then cool it naturally to room temperature;

[0078] (2) Add modified polysiloxane and lubricant to the dried inorganic powder, mix evenly, add diluent, stir evenly, and degas to obtain mixed adhesive.

[0079] (3) After calendering, the upper structure uses release film and the lower structure uses PI film. After drying in the drying tunnel, cutting, and rewinding once, the product is obtained.

[0080] The vacuum drying temperature in step 1 is 180℃, and the drying time is 4 hours.

[0081] The degassing pressure in step 2 is -1 mPa, and the degassing time is 30 min.

[0082] The drying tunnel temperature in step 3 is 120℃, the tunnel length is 12m, and the drying speed is 1m / min. The calendering thickness in step 3 is 0.15mm.

[0083] Performance testing

[0084] 1. Thickness: The thickness of the high thermal conductivity insulating sheet prepared according to ASTM D374 test examples 1-3.

[0085] 2. Contact thermal resistance: The contact thermal resistance of the high thermal conductivity insulating sheet prepared according to ASTM 5470 test examples 1-3.

[0086] 3. Thermal conductivity: The thermal conductivity of the high thermal conductivity insulating sheets prepared in Examples 1-3 was tested according to ISO22007-2.

[0087] 4. Breakdown voltage: The breakdown voltage of the high thermal conductivity insulating sheet prepared in Examples 1-3 was tested according to ASTM D149.

[0088] The test results are shown in Table 1.

[0089] Table 1

[0090] Comparative Example 1 Comparative Example 2 Example 1 Example 2 Thickness (mm) 0.07 0.15 0.03 0.04 <![CDATA[Thermal resistance (°C cm 2 / W)]]> 1.82 2.11 1.45 1.52 Thermal conductivity (W / m·K) 0.725 3.324 1.458 1.626 Dielectric strength (kV / mm) 26 29 28 28

Claims

1. A low-contact thermal resistance thermally conductive silicone cloth, characterized in that, The raw materials for preparation include, by weight: 15 parts modified polysiloxane, 160 parts inorganic powder, 0.3 parts lubricant, and 7 parts diluent; The modified polysiloxane is a vinyl-modified polysiloxane with a vinyl content of 0.18 wt% or 0.28 wt%. The inorganic powder is a combination of alumina and boron nitride; the alumina is a combination of spherical alumina with a particle size of 10 μm, spherical alumina with a particle size of 3 μm, and ellipsoidal alumina with a particle size of 0.5 μm; the boron nitride has a particle size of 5 μm; the weight ratio of the spherical alumina with a particle size of 10 μm, the spherical alumina with a particle size of 3 μm, the ellipsoidal alumina with a particle size of 0.5 μm and the boron nitride is 90:40:20:10; The diluent is acetone. The lubricant is an octyltriethoxysilane coupling agent. The preparation method of the low-contact thermal resistance thermally conductive silicone cloth includes the following steps: (1) Vacuum dry the inorganic powder and then let it cool naturally to room temperature; (2) Add modified polysiloxane and lubricant to the dried inorganic powder, mix evenly, add diluent, stir evenly, and degas to obtain mixed adhesive; (3) Apply the mixed adhesive to the base film, use a coating scraper to spread it evenly, dry it in the drying tunnel, cut it, and rewind it once to form a roll.

2. The low-contact thermal resistance thermally conductive silicone cloth according to claim 1, characterized in that, The modified polysiloxane has a viscosity of 30-550000 mPa•s at 25°C.

3. A method for preparing a low-contact thermal resistance thermally conductive silicone cloth according to any one of claims 1-2, characterized in that, Includes the following steps: (1) Vacuum dry the inorganic powder and then let it cool naturally to room temperature; (2) Add modified polysiloxane and lubricant to the dried inorganic powder, mix evenly, add diluent, stir evenly, and degas to obtain mixed adhesive; (3) Apply the mixed adhesive to the base film, use a coating scraper to spread it evenly, dry it in the drying tunnel, cut it, and rewind it once to form a roll.