Thermally conductive material composition, boron nitride fiber thermally conductive material, and method for producing the same

Abstract

The present application relates to the technical field of interface heat-conducting material, and particularly relates to a composition for heat-conducting material, a boron nitride fiber heat-conducting material and a preparation method thereof. The composition comprises: vinyl silicone oil, hydrogen-containing silicone oil, inhibitor, catalyst and modified boron nitride fiber. The heat-conducting material prepared by using the composition has excellent insulation, heat-conducting property and mechanical property.

Description

Technical Field

[0001] This invention relates to the field of interface thermal conductive materials technology, specifically to compositions for thermal conductive materials, boron nitride fiber thermal conductive materials, and methods for their preparation. Background Technology

[0002] Interfacial thermal conductive materials are commonly used for electronic heat dissipation. With the rapid development of microelectronic chips, the requirements for electronic heat dissipation are becoming increasingly stringent, which in turn places higher demands on interfacial thermal conductive materials. Silicone thermal pads, as a type of interfacial thermal conductive material, are basically made by filling silicone with thermally conductive fillers. Common thermally conductive fillers include alumina, zinc oxide, aluminum nitride, and boron nitride. Among them, boron nitride has the highest thermal conductivity, with powder generally exceeding 200 W / mK. The thermal conductivity of the thermal conductive material prepared by filling it into silicone is generally 1-10 W / mK. In order to improve the thermal conductivity of the thermal conductive material, the amount of thermally conductive filler added is generally increased during the preparation of the thermal conductive material. However, excessive filler will affect the mechanical properties of the final thermal conductive material.

[0003] Furthermore, since silicone is a long-chain organic polymer and thermally conductive powder is an inorganic ceramic material, there are a large number of unbonded atoms between them, and vibrations cannot be transmitted in this interface, resulting in very high interfacial thermal resistance. This makes it difficult to improve the thermal conductivity of the overall thermally conductive silicone pad. To solve the above problems, carbon fiber is currently used as a thermally conductive filler, but carbon fiber is a conductive material, so its application is not widespread at present. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of poor insulation and / or poor thermal conductivity of carbon fiber thermal conductive materials in the prior art, and to provide a new composition for thermal conductive materials, a boron nitride fiber thermal conductive material and its preparation method. The composition for thermal conductive materials uses boron nitride fiber as the main body, which has insulation properties and can also achieve good thermal conductivity.

[0005] The first aspect of the present invention provides a composition for a thermally conductive material, wherein the composition comprises: vinyl silicone oil, hydrogen-containing silicone oil, inhibitor, catalyst, and modified boron nitride fiber.

[0006] In some preferred embodiments, the composition for the thermally conductive material comprises, by weight, 100 parts vinyl silicone oil, 1-15 parts hydrogen-containing silicone oil, 0.01-0.5 parts inhibitor, 0.05-0.5 parts catalyst, and 1000-2000 parts modified boron nitride fiber.

[0007] In some preferred embodiments, the composition for the thermally conductive material comprises, by weight, 100 parts vinyl silicone oil, 4-6 parts hydrogen-containing silicone oil, 0.01-0.03 parts inhibitor, 0.1-0.3 parts catalyst, and 1500-2000 parts modified boron nitride fiber.

[0008] In some preferred embodiments, the composition for the thermally conductive material comprises, by weight, 100 parts vinyl silicone oil, 5 parts hydrogen-containing silicone oil, 0.02 parts inhibitor, 0.2 parts catalyst, and 1800 parts modified boron nitride fiber.

[0009] In some embodiments, the vinyl silicone oil has a viscosity of 800-1200 mm at 25°C. 2 / s, vinyl content is 0.19-0.23wt%.

[0010] In this invention, the source of the vinyl silicone oil is not particularly limited as long as the purpose of this invention can be achieved. Preferably, the vinyl silicone oil is purchased from Ningbo Runhe High-Tech Materials Technology Co., Ltd., and the model is RH-Vi305B.

[0011] In some embodiments, the hydrogen-containing silicone oil comprises a combination of hydrogen-terminated polydimethylsiloxane and partially hydrogen-terminated polydimethylsiloxane, preferably in a weight ratio of 1:(0.8-1.2).

[0012] In this invention, although the use of modified boron nitride fibers can increase the thermal conductivity and tensile strength of the thermally conductive material, the resulting boron nitride fiber thermally conductive material is prone to oil seepage, possibly due to the morphology of the modified boron nitride fibers themselves. The inventors unexpectedly discovered that using a specific combination of hydrogen-terminated polydimethylsiloxane and partially hydrogen-terminated polydimethylsiloxane can reduce the oil seepage rate of the prepared boron nitride fiber thermally conductive material. The inventors speculate that hydrogen-terminated polydimethylsiloxane can reduce the ductility of the system, while partially hydrogen-terminated polydimethylsiloxane can reduce the crosslinking density of the system. At the same time, due to the different structures of the two, they can form a cross-stacked structure in the system, making the crosslinking structure of the system more complex, which can better lock the small molecular structure in the system and reduce the oil seepage rate of the material.

[0013] In some preferred embodiments, the hydrogen-terminated polydimethylsiloxane has a viscosity of 60-70 mm at 25°C. 2 / s, with a hydrogen content of 0.04-0.05%.

[0014] In this invention, as long as the purpose of this invention can be achieved, the source of the hydrogen-terminated polydimethylsiloxane is not particularly limited. Preferably, the hydrogen-terminated polydimethylsiloxane is purchased from Ningbo Runhe High-Tech Materials Technology Co., Ltd., and the model is RH-DH04.

[0015] In some preferred embodiments, the partially hydrogen-terminated polydimethylsiloxane has a viscosity of 80-100 mm at 25°C. 2 / s, with a hydrogen content of 0.01-0.03%.

[0016] In this invention, as long as the purpose of this invention can be achieved, the source of the partially hydrogen-capped polydimethylsiloxane is not particularly limited. Preferably, the partially hydrogen-capped polydimethylsiloxane is purchased from Ningbo Runhe High-Tech Materials Technology Co., Ltd., and the model is RH-222-3.

[0017] In this invention, the addition of inhibitors serves to suppress the crosslinking reaction between vinyl silicone oil and hydrogen-containing silicone oil, preventing the crosslinking rate from being too fast during the preparation process, which would affect the uniformity and performance of the raw materials. In some preferred embodiments, the inhibitors are alkynyl alcohol compounds, such as ethynylcyclohexanol and / or methylbutynol.

[0018] In this invention, the catalyst may be a commonly used catalyst in the art, such as a platinum group catalyst, preferably a Karstedt platinum catalyst.

[0019] The method for preparing the modified boron nitride fiber includes:

[0020] S1 dimethyl sulfoxide, strong base and aramid nanofibers are mixed to obtain dispersion A;

[0021] S2 mixes boron nitride fiber with dimethyl sulfoxide to obtain dispersion B;

[0022] S3 mixes dispersion B and dispersion A and then pushes them into a thin film using a quartz rod. The film is then regenerated in water until it floats. Finally, it is washed with water until neutral and dried to obtain a composite film with a thickness of 30-40 micrometers.

[0023] S4 cuts the composite film into modified boron nitride fibers with a width of 50-100 micrometers and a length of 80-150 millimeters.

[0024] In this invention, there are no special restrictions on the amount of dimethyl sulfoxide, strong base, and aramid nanofibers used in step S1, as long as the amount of dimethyl sulfoxide and strong base is sufficient to ensure that there is no solid residue in dispersion A. In some embodiments, the mass ratio of dimethyl sulfoxide, strong base, and aramid nanofibers in step S1 is 100:(1-5):(1-5), preferably 100:2.5:2.

[0025] In some embodiments, in step S1, the strong base is selected from at least one of potassium tert-butoxide, sodium methoxide, sodium tert-butoxide, potassium tert-butoxide, and sodium hydroxide, preferably potassium ethoxide.

[0026] In some embodiments, the aramid nanofibers are selected from Kevlar 29.

[0027] In some embodiments, in step S2, the mass ratio of boron nitride fiber to dimethyl sulfoxide is (2-10):100, preferably (3-5):100.

[0028] In some embodiments, in step S3, the mass ratio of boron nitride fibers in dispersion B to aramid nanofibers in dispersion A is 1:(1-5), preferably 1:(1.6-2.5).

[0029] In some embodiments, in step S3, the boron nitride fiber is composed of boron nitride fiber A with a particle size of 300-350 mesh and boron nitride fiber B with a particle size of 600-100 mesh, and the weight ratio is 1:(0.8-1.2).

[0030] In this invention, boron nitride fiber A and boron nitride fiber B are distinguished only by their different particle sizes.

[0031] In this invention, the inventors discovered that using two boron nitride fibers of different particle sizes in interaction can better increase the thermal conductivity of the thermally conductive material. This may be because the two boron nitride fibers of different particle sizes can enable the prepared modified boron nitride fibers to form a denser network structure in the system during the modification process.

[0032] In this invention, water washing and drying are conventional techniques in the field, and will not be described in detail here.

[0033] In this invention, the cutting method in step S4 can be any method well known in the art, such as laser cutting.

[0034] In this invention, the inventors discovered through research that using the specific modified boron nitride fibers described in this invention within the boron nitride fiber thermal conductive material not only increases the material's temperature resistance but also mitigates the defect that using boron nitride fibers alone reduces the material's tensile strength. The inventors hypothesize that during the preparation of the modified boron nitride fibers, aramid nanofibers can become entangled with boron nitride through multiple hydrogen bonds, forming a connected network in the system. This allows the material containing the specific modified boron nitride fibers described in this invention to undergo stress transfer under external force, with stress evenly distributed between the connected networks. However, the research revealed that the ratio of aramid nanofibers to boron nitride fibers must be strictly controlled. When the mass ratio of boron nitride fibers in dispersion B to aramid nanofibers in dispersion A is 1:(1-5), especially 1:(1.6-2.5), the thermal conductivity and tensile strength of the thermal conductive material can simultaneously reach their optimal levels.

[0035] A second aspect of the present invention provides a method for preparing a boron nitride fiber thermally conductive material, wherein the preparation method includes:

[0036] (1) Take modified boron nitride fibers and arrange them in a mold in an orientation;

[0037] (2) Mix vinyl silicone oil, hydrogen-containing silicone oil, inhibitor and catalyst to obtain mixture A;

[0038] (3) Pour the mixture A onto the modified boron nitride fiber and perform ultrasonic vibration;

[0039] (4) Then place the mold in a 110-150℃ environment and cure for 1-5 hours to obtain the block.

[0040] (5) The block is sliced ​​along the vertically modified boron nitride fibers to obtain the boron nitride fiber thermal conductive material.

[0041] In this invention, "directional arrangement" refers to the arrangement of modified boron nitride fibers in one direction.

[0042] In this invention, there are no special restrictions on the mixing method in step (2), and any mixing method in the art can be used; there are no special restrictions on the conditions of ultrasonic vibration in step (3), as long as the mixture A can be completely wetted by the modified boron nitride fiber.

[0043] In this invention, boron nitride fiber thermal conductive material can be sliced ​​into the required thickness, for example, 1-5 mm, as needed.

[0044] The third aspect of the present invention provides a boron nitride fiber thermal conductive material prepared according to the second aspect of the present invention. Detailed Implementation

[0045] The present invention will be described in detail below through embodiments, including comparative examples:

[0046] The vinyl silicone oil was purchased from Ningbo Runhe Advanced Materials Technology Co., Ltd., model number RH-Vi305B; the hydrogen-terminated polydimethylsiloxane was purchased from Ningbo Runhe Advanced Materials Technology Co., Ltd., model number RH-DH04; and the partially hydrogen-terminated polydimethylsiloxane was purchased from Ningbo Runhe Advanced Materials Technology Co., Ltd., model number RH-222-3.

[0047] Example 1

[0048] Preparation of modified boron nitride fibers:

[0049] S1 mixes dimethyl sulfoxide, a strong base, and aramid nanofibers in a mass ratio of 100:2.5:2 to obtain dispersion A;

[0050] S2 mixes boron nitride fibers (boron nitride fiber A with a particle size of 325 mesh and boron nitride fiber B with a particle size of 800 mesh in a weight ratio of 1:1) with dimethyl sulfoxide to obtain dispersion B;

[0051] S3 mixes dispersion B with dispersion A (the mass ratio of boron nitride fibers in dispersion B to aramid nanofibers in dispersion A is 1:2) and then pushes it into a thin film using a quartz rod. After that, it is sent to water for regeneration until the film floats. Finally, it is washed with water until neutral and dried to obtain a composite film with a thickness of 35 micrometers.

[0052] S4 cuts the composite film into modified boron nitride fibers with a width of 80 micrometers and a length of 100 millimeters.

[0053] Preparation of boron nitride fiber thermal conductive materials:

[0054] (1) Weigh out 100 parts of vinyl silicone oil, 5 parts of hydrogen-containing silicone oil, 0.02 parts of inhibitor, 0.2 parts of catalyst, and 1800 parts of modified boron nitride fiber by weight for later use.

[0055] (2) The modified boron nitride fibers prepared above are oriented and arranged in a mold;

[0056] (3) Mix vinyl silicone oil, hydrogen-capped polydimethylsiloxane in a mass ratio of 1:1 with a portion of hydrogen-capped polydimethylsiloxane, ethynylcyclohexanol and Karstedt platinum catalyst to obtain mixture A.

[0057] (4) Pour mixture A onto the modified boron nitride fiber and perform ultrasonic vibration;

[0058] (5) Then place the mold in a container and cure it at 120°C for 1.5 hours to obtain the block.

[0059] (6) The block was sliced ​​along the vertical modified boron nitride fibers to obtain a boron nitride fiber thermal conductive material with a thickness of 2 mm.

[0060] Example 2

[0061] Preparation of modified boron nitride fibers:

[0062] S1 mixes dimethyl sulfoxide, strong base and aramid nanofibers in a mass ratio of 100:3:3 to obtain dispersion A;

[0063] S2 mixes boron nitride fibers (boron nitride fiber A with a particle size of 325 mesh and boron nitride fiber B with a particle size of 800 mesh in a weight ratio of 1:1) with dimethyl sulfoxide to obtain dispersion B;

[0064] S3 mixes dispersion B with dispersion A (the mass ratio of boron nitride fibers in dispersion B to aramid nanofibers in dispersion A is 1:2.5) and then pushes it into a thin film using a quartz rod. After that, it is sent to water for regeneration until the film floats. Finally, it is washed with water until neutral and dried to obtain a composite film with a thickness of 35 micrometers.

[0065] S4 cuts the composite film into modified boron nitride fibers with a width of 80 micrometers and a length of 100 millimeters.

[0066] Preparation of boron nitride fiber thermal conductive materials:

[0067] (1) Weigh out 100 parts of vinyl silicone oil, 4 parts of hydrogen-containing silicone oil, 0.02 parts of inhibitor, 0.2 parts of catalyst, and 1600 parts of modified boron nitride fiber by weight for later use.

[0068] (2) The modified boron nitride fibers prepared above are oriented and arranged in a mold;

[0069] (3) Mix vinyl silicone oil, hydrogen-capped polydimethylsiloxane in a mass ratio of 1:0.8 with a portion of hydrogen-capped polydimethylsiloxane, methylbutynol, and Karstedt platinum catalyst to obtain mixture A;

[0070] (4) Pour mixture A onto the modified boron nitride fiber and perform ultrasonic vibration;

[0071] (5) Then the mold is placed in the mold and cured at 130°C for 1 hour to obtain the block;

[0072] (6) The block was sliced ​​along the vertical modified boron nitride fibers to obtain a boron nitride fiber thermal conductive material with a thickness of 2 mm.

[0073] Example 3

[0074] Preparation of modified boron nitride fibers:

[0075] S1 mixes dimethyl sulfoxide, a strong base, and aramid nanofibers in a mass ratio of 100:2.5:3 to obtain dispersion A;

[0076] S2 mixes boron nitride fibers (boron nitride fiber A with a particle size of 325 mesh and boron nitride fiber B with a particle size of 800 mesh) with dimethyl sulfoxide at a mass ratio of 5:100 to obtain dispersion B;

[0077] S3 mixes dispersion B with dispersion A (the mass ratio of boron nitride fibers in dispersion B to aramid nanofibers in dispersion A is 1:2.5) and then pushes it into a thin film using a quartz rod. After that, it is sent to water for regeneration until the film floats. Finally, it is washed with water until neutral and dried to obtain a composite film with a thickness of 35 micrometers.

[0078] S4 cuts the composite film into modified boron nitride fibers with a width of 80 micrometers and a length of 100 millimeters.

[0079] Preparation of boron nitride fiber thermal conductive materials:

[0080] (1) Weigh out 100 parts of vinyl silicone oil, 6 parts of hydrogen-containing silicone oil, 0.04 parts of inhibitor, 0.3 parts of catalyst, and 1800 parts of modified boron nitride fiber by weight for later use.

[0081] (2) The modified boron nitride fibers prepared above are oriented and arranged in a mold;

[0082] (3) Mix vinyl silicone oil, hydrogen-capped polydimethylsiloxane in a mass ratio of 1:1.2 with a portion of hydrogen-capped polydimethylsiloxane, methylbutynol, and Karstedt platinum catalyst to obtain mixture A;

[0083] (4) Pour mixture A onto the modified boron nitride fiber and perform ultrasonic vibration;

[0084] (5) Then the mold is placed in the mold and cured at 120°C for 2 hours to obtain the block;

[0085] (6) The block was sliced ​​along the vertical modified boron nitride fibers to obtain a boron nitride fiber thermal conductive material with a thickness of 2 mm.

[0086] Example 4

[0087] The method described in Example 1 differs in that:

[0088] Five parts by weight of hydrogen-capped polydimethylsiloxane were used to replace some of the hydrogen-capped polydimethylsiloxane; the rest was the same as in Example 1, and boron nitride fiber thermal conductive material was finally prepared.

[0089] Example 5

[0090] The method described in Example 1 differs in that:

[0091] Five parts by weight of partially hydrogen-capped polydimethylsiloxane were used to replace the hydrogen-capped polydimethylsiloxane and partially hydrogen-capped polydimethylsiloxane; the rest was the same as in Example 1, and boron nitride fiber thermal conductive material was finally prepared.

[0092] Example 6

[0093] The method described in Example 1 differs in that:

[0094] When preparing modified boron nitride fibers, the mass ratio of boron nitride fibers in dispersion B to aramid nanofibers in dispersion A is 1:0.8. Modified boron nitride fibers are then prepared using these modified boron nitride fibers according to the method in Example 1 to obtain boron nitride fiber thermal conductive materials.

[0095] Comparative Example 1

[0096] Preparation of boron nitride fiber thermal conductive materials:

[0097] (1) Weigh out 100 parts of vinyl silicone oil, 5 parts of hydrogen-containing silicone oil, 0.02 parts of inhibitor, 0.2 parts of catalyst, and 1800 parts of boron nitride fiber (boron nitride fiber A with a particle size of 325 mesh and boron nitride fiber B with a particle size of 800 mesh in a weight ratio of 1:1) by weight for later use.

[0098] (2) Mix vinyl silicone oil, hydrogen-capped polydimethylsiloxane in a mass ratio of 1:1, a portion of hydrogen-capped polydimethylsiloxane, ethynylcyclohexanol, Karstedt platinum catalyst and boron nitride fiber to obtain mixture A.

[0099] (3) Pour the mixture A into the mold;

[0100] (4) Then the mold is placed in the mold and cured at 120°C for 1.5 hours to obtain the block;

[0101] (5) The block is sliced ​​to obtain a 2mm thick boron nitride fiber thermal conductive material.

[0102] Performance testing

[0103] The boron nitride fiber thermal conductive materials prepared in the examples and comparative examples were tested as follows, and the test results are shown in Table 1.

[0104] 1. Thermal conductivity:

[0105] Thermal conductivity was tested according to ASTM D 5470 standard (pressure 50 psi, along the direction perpendicular to the modified boron nitride fiber);

[0106] 2. Tensile strength:

[0107] The tensile strength in the horizontal direction (perpendicular to the modified boron nitride fiber) was tested according to ASTM D 412 standard.

[0108] 3. Oil seepage rate:

[0109] Test method: The prepared boron nitride fiber thermal conductive material was clamped on both sides with steel plates, and filter paper (the size of the filter paper is larger than the size of the boron nitride fiber thermal conductive material) was sandwiched between the steel plates and the thermal conductive material. The clamping pressure was 30Psi, and then the filter paper was weighed after being placed at 130℃ for 48h.

[0110] Oil penetration rate = (increased mass of filter paper / original mass of boron nitride fiber thermal conductive material) * 100%.

[0111] Table 1

[0112]

Claims

1. A composition for use in thermally conductive materials, characterized in that, The composition for the thermally conductive material comprises, by weight, 100 parts of vinyl silicone oil, 1-15 parts of hydrogen-containing silicone oil, 0.01-0.5 parts of inhibitor, 0.05-0.5 parts of catalyst, and 1000-2000 parts of modified boron nitride fiber. The hydrogen-containing silicone oil includes a combination of hydrogen-terminated polydimethylsiloxane and a portion of hydrogen-terminated polydimethylsiloxane; The method for preparing the modified boron nitride fiber includes: S1 dimethyl sulfoxide, strong base and aramid nanofibers are mixed to obtain dispersion A; S2. Boron nitride fiber is mixed with dimethyl sulfoxide to obtain dispersion B; S3 After mixing dispersion B and dispersion A, a quartz rod is used to push the mixture into a thin film. The mass ratio of boron nitride fibers in dispersion B to aramid nanofibers in dispersion A is 1:(1-5). The film is then regenerated in water until it floats. Finally, it is washed with water until it is neutral and dried to obtain a composite film with a thickness of 30-40 micrometers. S4 cuts the composite film into pieces with a width of 50-100 micrometers and a length of 80-150 millimeters.

2. The composition according to claim 1, characterized in that, The vinyl silicone oil has a viscosity of 800-1200 mm at 25°C. 2 / s, vinyl content is 0.19-0.23wt%.

3. The composition according to claim 1, characterized in that, The hydrogen-terminated polydimethylsiloxane has a viscosity of 60-70 mm at 25°C. 2 / s, hydrogen content of 0.04-0.05%; the viscosity of the partially hydrogen-terminated polydimethylsiloxane at 25°C is 80-100 mm. 2 / s, with a hydrogen content of 0.01-0.03%.

4. The composition according to claim 1, characterized in that, In step S1, the mass ratio of dimethyl sulfoxide, strong alkali, and aramid nanofibers is 100:(1-5):(1-5).

5. A method for preparing a composition for a thermally conductive material according to any one of claims 1-4, characterized in that, The preparation method includes: (1) Take modified boron nitride fibers and arrange them in a mold in an orientation; (2) Mix vinyl silicone oil, hydrogen-containing silicone oil, inhibitor, and catalyst to obtain mixture A; (3) Pour mixture A onto the modified boron nitride fiber and subject it to ultrasonic vibration; (4) Then place the mold in a 110-150℃ environment and cure for 1-5 hours to obtain the block; (5) The block is sliced ​​along the vertically modified boron nitride fibers to obtain boron nitride fiber thermal conductive material.

6. A boron nitride fiber thermal conductive material prepared by the preparation method of claim 5.

Images