CN117887272A - Heat-conducting composite material and preparation method thereof - Google Patents
Heat-conducting composite material and preparation method thereof Download PDFInfo
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- CN117887272A CN117887272A CN202410123604.9A CN202410123604A CN117887272A CN 117887272 A CN117887272 A CN 117887272A CN 202410123604 A CN202410123604 A CN 202410123604A CN 117887272 A CN117887272 A CN 117887272A
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- 238000002360 preparation method Methods 0.000 title claims abstract description 20
- 239000000463 material Substances 0.000 claims abstract description 103
- 238000004513 sizing Methods 0.000 claims abstract description 97
- 238000003756 stirring Methods 0.000 claims abstract description 84
- 239000000945 filler Substances 0.000 claims abstract description 58
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- 238000000034 method Methods 0.000 claims abstract description 42
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- 238000002156 mixing Methods 0.000 claims abstract description 39
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- 239000003054 catalyst Substances 0.000 claims abstract description 21
- 238000005859 coupling reaction Methods 0.000 claims abstract description 18
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- 239000003112 inhibitor Substances 0.000 claims abstract description 15
- 238000010438 heat treatment Methods 0.000 claims abstract description 13
- 239000000203 mixture Substances 0.000 claims abstract description 10
- 238000003825 pressing Methods 0.000 claims abstract description 7
- 229910052739 hydrogen Inorganic materials 0.000 claims description 22
- 239000001257 hydrogen Substances 0.000 claims description 22
- 239000011231 conductive filler Substances 0.000 claims description 20
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 10
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical group [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 10
- -1 dodecyl siloxane Chemical class 0.000 claims description 9
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 8
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims description 8
- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims description 8
- 230000035699 permeability Effects 0.000 claims description 7
- 238000004321 preservation Methods 0.000 claims description 7
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- 239000010432 diamond Substances 0.000 claims description 5
- 229910052697 platinum Inorganic materials 0.000 claims description 5
- NMEPHPOFYLLFTK-UHFFFAOYSA-N trimethoxy(octyl)silane Chemical compound CCCCCCCC[Si](OC)(OC)OC NMEPHPOFYLLFTK-UHFFFAOYSA-N 0.000 claims description 5
- QYLFHLNFIHBCPR-UHFFFAOYSA-N 1-ethynylcyclohexan-1-ol Chemical group C#CC1(O)CCCCC1 QYLFHLNFIHBCPR-UHFFFAOYSA-N 0.000 claims description 4
- 239000004480 active ingredient Substances 0.000 claims description 4
- 239000011787 zinc oxide Substances 0.000 claims description 4
- 150000004645 aluminates Chemical class 0.000 claims description 3
- SNRUBQQJIBEYMU-UHFFFAOYSA-N Dodecane Natural products CCCCCCCCCCCC SNRUBQQJIBEYMU-UHFFFAOYSA-N 0.000 claims description 2
- VDABAEUEVYDURI-UHFFFAOYSA-N [dimethoxy(propyl)silyl]oxymethyl acetate Chemical compound CCC[Si](OC)(OC)OCOC(C)=O VDABAEUEVYDURI-UHFFFAOYSA-N 0.000 claims description 2
- XNGIFLGASWRNHJ-UHFFFAOYSA-L phthalate(2-) Chemical compound [O-]C(=O)C1=CC=CC=C1C([O-])=O XNGIFLGASWRNHJ-UHFFFAOYSA-L 0.000 claims description 2
- 230000008569 process Effects 0.000 description 29
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Abstract
The invention provides a heat-conducting composite material and a preparation method thereof, and belongs to the technical field of functional material preparation. The preparation method comprises the steps of carrying out first stirring and mixing on vinyl silicone oil and a coupling agent, and carrying out second stirring and mixing on the obtained mixture and a heat-conducting filler to obtain a sizing material A; heating the sizing material A under the stirring condition to perform coupling reaction to obtain a sizing material B; heating the sizing material B under the stirring condition to carry out vacuum kneading treatment to obtain sizing material C; thirdly stirring and mixing the sizing material C, the inhibitor and the cross-linking agent under the vacuum condition to obtain a sizing material D; stirring and mixing the sizing material D and the catalyst for the fourth time under the vacuum condition to obtain a sizing material E; and (3) sequentially pressing and curing the sizing material E to obtain the heat-conducting composite material. The method provided by the invention can be used for preparing the heat-conducting composite material with excellent comprehensive performance, and is simple in operation, safe, environment-friendly and low in cost.
Description
Technical Field
The invention relates to the technical field of functional material preparation, in particular to a heat-conducting composite material and a preparation method thereof.
Background
With the rapid development of various industries and fields such as electronic appliances, aerospace, weaponry, 5G communication and the like, the integration, miniaturization and high-power requirements of electronic equipment facilities and semiconductor materials are increasingly increased, and therefore, the high heat output brings higher requirements on the heat conducting performance, reliability and long-term usability of the heat conducting material.
The high heat conduction filler such as diamond, aluminum nitride, carbon fiber and the like is limited to be singly used in the heat conduction composite material due to the problems of overhigh cost, overlarge oil absorption value and the like, so that the traditional heat conduction filler such as aluminum oxide is still widely used for preparing the heat conduction composite material, and the improvement of the filling amount of the traditional heat conduction filler is still a main means for improving the heat conductivity of the heat conduction composite material at the present stage.
At present, filler modification and the addition of coupling agents are two methods that are effective in increasing filler loading. The modifier used for modifying the filler is usually an amphoteric modifier, a firm chemical bond can be formed between the modifier and the filler, and a physical coating layer can be formed on the surface of the filler by adding the coupling agent. For example, in patent CN 111675908a, a heat conductive filler and a coupling agent are mixed and then modified by a dry method in a high-speed mixer, and after being dried, the mixture is mixed with silicone oil with an organic matrix to increase the filling amount of the heat conductive filler; in the patent CN 111635636A, ethanol is used as a solvent to carry out wet modification on the heat-conducting filler, and the heat-conducting filler is dried and then mixed with silicone oil, so that the high-heat-conducting ageing-resistant heat-conducting gasket is prepared based on the heat-conducting filler; in CN 105733270a, a coupling agent is directly added into a heat conductive filler to form a physical coating, and then mixed with silicone oil, so as to increase the filling amount of the heat conductive filler. However, the filler treatment process in the prior art has defects such as complex wet modification process, and needs a large amount of solvent, so that the cost is high and the environment is not protected; the wetting effect of the liquid-solid interface between the filler and the coupling agent in the dry process is limited by the small amount of the coupling agent, so that the contact sites are small, and the good modification effect is difficult to achieve; in the process of directly adding the coupling agent to physically coat the heat-conducting filler, the acting force between the coupling agent and the heat-conducting filler is weak, the coupling agent and the heat-conducting filler are easy to damage, and the stability is poor.
Disclosure of Invention
The invention aims to provide a heat-conducting composite material and a preparation method thereof, and the heat-conducting composite material with excellent comprehensive performance can be prepared by adopting the method provided by the invention, and the method is simple in operation, safe and environment-friendly and low in cost.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of a heat-conducting composite material, which comprises the following steps:
The vinyl silicone oil and the coupling agent are subjected to first stirring and mixing, and the obtained mixture and the heat conducting filler are subjected to second stirring and mixing to obtain a sizing material A;
heating the sizing material A under the stirring condition to perform coupling reaction to obtain a sizing material B;
heating the sizing material B under the stirring condition to carry out vacuum kneading treatment to obtain sizing material C;
Thirdly stirring and mixing the sizing material C, the inhibitor and the cross-linking agent under the vacuum condition to obtain a sizing material D;
stirring and mixing the sizing material D and the catalyst for the fourth time under the vacuum condition to obtain a sizing material E;
and (3) sequentially pressing and curing the sizing material E to obtain the heat-conducting composite material.
Preferably, the viscosity of the vinyl silicone oil is 100-5000 cp, and the molar content of vinyl in the vinyl silicone oil is 0.3-1.5%;
the coupling agent comprises one or more of acetoxyl propyl trimethoxy silane, n-octyl trimethoxy silane, dodecyl siloxane, hexadecyl siloxane, octadecyl siloxane, phthalate and aluminate;
The heat conducting filler comprises one or more of aluminum oxide, zinc oxide, aluminum nitride and diamond, and the mass fraction of the aluminum oxide in the heat conducting filler is 50-100%.
Preferably, the mass ratio of the vinyl silicone oil to the heat-conducting filler is 1: 10-40% of coupling agent, wherein the mass of the coupling agent is 0.1-2.0% of the mass of the heat conducting filler.
Preferably, the stirring speed of the first stirring and mixing and the second stirring and mixing is independently 20-1000 rpm, and the stirring time is independently 5-60 min.
Preferably, the temperature of the coupling reaction is 40-100 ℃, the time is 30-90 min, and the stirring speed is 20-1000 rpm.
Preferably, the temperature of the vacuum kneading treatment is 120-170 ℃, the time is 60-120 min, and the stirring speed is 20-1000 rpm.
Preferably, the inhibitor is ethynyl cyclohexanol, and the mass of the inhibitor is 0.01-0.5% of the mass of the sizing material C;
The cross-linking agent is hydrogen-containing silicone oil, and the mass of the cross-linking agent is 0.01-1.5% of the mass of the sizing material C;
The catalyst is a platinum catalyst, and the concentration of active ingredients in the catalyst is 100-10000 ppm.
Preferably, the stirring speed of the third stirring and mixing and the fourth stirring and mixing is independently 20-5000 rpm, and the stirring time is independently 30-60 min.
Preferably, the curing comprises sequentially performing a first stage curing and a second stage curing; the curing temperature in the first stage is 80-120 ℃, and the heat preservation time is 15-60 min; the curing temperature in the second stage is 125-150 ℃, and the heat preservation time is 15-30 min.
The invention provides the heat-conducting composite material prepared by the preparation method, wherein the heat conductivity coefficient is 2.0-15.0W/m.K, and the oil permeability is 0.5-2.0%.
The invention provides a preparation method of a heat-conducting composite material, which comprises the following steps: the vinyl silicone oil and the coupling agent are subjected to first stirring and mixing, and the obtained mixture and the heat conducting filler are subjected to second stirring and mixing to obtain a sizing material A; heating the sizing material A under the stirring condition to perform coupling reaction to obtain a sizing material B; heating the sizing material B under the stirring condition to carry out vacuum kneading treatment to obtain sizing material C; thirdly stirring and mixing the sizing material C, the inhibitor and the cross-linking agent under the vacuum condition to obtain a sizing material D; stirring and mixing the sizing material D and the catalyst for the fourth time under the vacuum condition to obtain a sizing material E; and (3) sequentially pressing and curing the sizing material E to obtain the heat-conducting composite material. The method provided by the invention can be used for preparing the heat-conducting composite material with excellent comprehensive performance, and is simple in operation, safe, environment-friendly and low in cost. Specifically, the invention takes the organic matrix (vinyl silicone oil) as the solvent to increase the contact site between the heat conduction filler and the coupling agent, thereby being beneficial to improving the modification effect of the heat conduction filler; the invention combines the filler modification process and the sizing material high-temperature kneading process into a continuous process, simplifies the process flow, is beneficial to improving the production stability, and is safe and environment-friendly; the invention can effectively realize the modification of the heat conducting filler and the high-temperature kneading of the sizing material in a high-temperature period, thereby reducing the energy consumption.
Detailed Description
The invention provides a preparation method of a heat-conducting composite material, which comprises the following steps:
The vinyl silicone oil and the coupling agent are subjected to first stirring and mixing, and the obtained mixture and the heat conducting filler are subjected to second stirring and mixing to obtain a sizing material A;
heating the sizing material A under the stirring condition to perform coupling reaction to obtain a sizing material B;
heating the sizing material B under the stirring condition to carry out vacuum kneading treatment to obtain sizing material C;
Thirdly stirring and mixing the sizing material C, the inhibitor and the cross-linking agent under the vacuum condition to obtain a sizing material D;
stirring and mixing the sizing material D and the catalyst for the fourth time under the vacuum condition to obtain a sizing material E;
and (3) sequentially pressing and curing the sizing material E to obtain the heat-conducting composite material.
In the prior art, the filler modification process and the sizing material high-temperature kneading process are usually two independent discontinuous production processes, and the discontinuous production processes have a plurality of key control conditions, are unfavorable in production stability control, and also have long production period and low productivity. According to the invention, the filler modification process and the high-temperature kneading process of the sizing material are combined into a continuous process, so that on the premise of ensuring excellent comprehensive performance of the product, the key control conditions are reduced, the risk of unstable production is reduced, the production period is shortened, the productivity is improved, and finally the cost is reduced. Specifically, the invention combines the filler modification process and the sizing material high-temperature kneading process into a whole, realizes the modification of the heat-conducting filler in the material mixing process, improves the compatibility of the heat-conducting filler and an organic matrix (vinyl silicone oil), and finally obtains the sizing material with uniform and stable structure, and compared with the stepwise wet modification, the invention can save a large amount of solvents, is environment-friendly and can reduce the cost; compared with the stepwise dry modification, the addition of the vinyl silicone oil can ensure that the coupling agent is better dispersed on the surface of the heat-conducting filler, increase the contact sites and ensure that the probability of the coupling reaction is greater, so the modification effect is good; compared with the direct physical coating coupling agent process, the chemical bond formed by the coupling reaction has better stability and better post-stability performance of the product. The method of the present invention will be described in detail.
In the present invention, the raw materials used are commercially available products well known to those skilled in the art unless specified otherwise.
According to the invention, vinyl silicone oil and a coupling agent are subjected to first stirring and mixing, and the obtained mixture and a heat conducting filler are subjected to second stirring and mixing, so that a sizing material A is obtained. In the invention, the viscosity of the vinyl silicone oil is preferably 100-5000 cp, and can be one or more of the vinyl silicone oils with the viscosity of 100cp, 500cp, 1000cp, 2000cp and 5000cp, preferably the vinyl silicone oil with the viscosity of 500 cp; the vinyl group content (mol/mol) of the vinyl silicone oil is preferably 0.3 to 1.5%, more preferably 0.5 to 1.0%. In the present invention, the coupling agent preferably includes one or more of acetoxypropyltrimethoxysilane, n-octyltrimethoxysilane, dodecylsiloxane, hexadecylsiloxane, octadecylsiloxane, phthalate and aluminate, more preferably n-octyltrimethoxysilane or hexadecylsiloxane. In the present invention, the heat conductive filler preferably includes one or more of alumina, zinc oxide, aluminum nitride, and diamond, and the mass fraction of alumina in the heat conductive filler is preferably 50 to 100%, more preferably 60 to 80%, still more preferably 65 to 77%, still more preferably 70 to 72%. In the invention, the heat conducting filler can be aluminum oxide, or can be a mixture of aluminum oxide and at least one of zinc oxide, aluminum nitride and diamond, and particularly can be a mixture of aluminum nitride and aluminum oxide, so that the mass fraction of aluminum oxide in the heat conducting filler can meet the requirements. In the present invention, the grading of the heat conductive filler is preferably: the heat conductive filler having a particle size of 90 to 150 μm preferably accounts for 20 to 60% of the total mass of the heat conductive filler (more preferably 40%), the heat conductive filler having a particle size of 40 to 90 μm preferably accounts for 10 to 30% of the total mass of the heat conductive filler (more preferably 20%), the heat conductive filler having a particle size of 10 to 40 μm preferably accounts for 5 to 20% of the total mass of the heat conductive filler (more preferably 12%), the heat conductive filler having a particle size of 1 to 10 μm preferably accounts for 10 to 40% of the total mass of the heat conductive filler (more preferably 20%), and the heat conductive filler having a particle size of 0.1 to 1 μm preferably accounts for 1 to 10% of the total mass of the heat conductive filler (more preferably 8%). In the invention, the mass ratio of the vinyl silicone oil to the heat-conducting filler is preferably 1:10 to 40, more preferably 1:15 to 34, more preferably 1:24 to 32, more preferably 1: 28-30 parts; the mass of the coupling agent is preferably 0.1 to 2.0%, more preferably 0.2 to 1.5%, still more preferably 0.3 to 1.0%, and still more preferably 0.4 to 0.7% of the mass of the heat conductive filler. In the present invention, the stirring rate of the first stirring and mixing is preferably 20 to 1000rpm, more preferably 30 to 100rpm; the stirring time is preferably 5 to 60 minutes, more preferably 5 to 15 minutes. In the present invention, the stirring rate of the second stirring and mixing is preferably 20 to 1000rpm, more preferably 20 to 100rpm; the stirring time is preferably 5 to 60 minutes, more preferably 10 to 20 minutes.
After the sizing material A is obtained, the sizing material A is heated under the stirring condition to carry out coupling reaction, so as to obtain the sizing material B. In the present invention, the temperature of the coupling reaction is preferably 40 to 100 ℃, more preferably 50 to 60 ℃; the time is preferably 30 to 90 minutes, more preferably 30 to 40 minutes; the stirring rate is preferably 20 to 1000rpm, more preferably 20 to 100rpm. The coupling reaction is preferably carried out under the stirring condition, which is favorable for ensuring that the coupling agent is fully contacted with the heat-conducting filler, so that the coupling reaction is fully carried out.
After the sizing material B is obtained, the sizing material B is heated under the stirring condition to be subjected to vacuum kneading treatment, so that the sizing material C is obtained. In the present invention, the temperature of the vacuum kneading treatment is preferably 120 to 170 ℃, more preferably 120 to 130 ℃; the time is preferably 60 to 120min, more preferably 60 to 70min; the stirring rate is preferably 20 to 1000rpm, more preferably 20 to 100rpm; the vacuum degree is preferably 0.08 to 0.1MPa, more preferably 0.09 to 0.1MPa. The invention preferably kneads under the conditions of the temperature and the vacuum degree, the viscosity of the vinyl silicone oil is reduced to be low enough, the vinyl silicone oil can better wet the surface of the heat-conducting filler, a denser structure is formed with the heat-conducting filler, so that the heat-conducting filler can be filled in a larger amount, and meanwhile, the coupling agent which is not reacted in the coupling reaction process and some small molecular vinyl silicone oil volatilize at high temperature (the volatilized material mass is about 0.1 percent of the mass of the whole sizing material system and does not influence the product yield), so that the residual quantity of the vinyl silicone oil in the sizing material system is reduced, and the rapid reduction of product defects and ageing performance caused by volatilization of the thermal-conducting composite material product in the subsequent curing step and the application process under the high-temperature environment is avoided. After the vacuum kneading treatment, the obtained material is preferably cooled to room temperature to obtain a sizing material C; the cooling mode and the cooling rate are not particularly limited, and the cooling can be carried out to room temperature.
After the sizing material C is obtained, the sizing material C, the inhibitor and the cross-linking agent are subjected to third stirring and mixing under the vacuum condition to obtain the sizing material D. In the present invention, the inhibitor is preferably ethynyl cyclohexanol, and the mass of the inhibitor is preferably 0.01 to 0.5%, more preferably 0.02 to 0.4%, still more preferably 0.03 to 0.3%, still more preferably 0.04 to 0.2%, still more preferably 0.05 to 0.1% of the mass of the compound C. In the present invention, the crosslinking agent is preferably hydrogen-containing silicone oil; the hydrogen-containing silicone oil preferably comprises terminal hydrogen-containing silicone oil and side hydrogen-containing silicone oil, and the molar ratio of the terminal hydrogen-containing silicone oil to the side hydrogen-containing silicone oil is preferably 0.1-3: 1, more preferably 0.15:1, a step of; the hydrogen-containing silicone oil preferably has a hydrogen concentration (g/g) of 0.08 to 1.0wt%, and may specifically be one or more of hydrogen-containing silicone oils having a hydrogen concentration of 0.08wt%, 0.18wt%, 0.5wt% and 1.0wt%, preferably hydrogen-containing silicone oils having a hydrogen concentration of 0.18 wt%; the mass of the crosslinking agent is preferably 0.01 to 1.5%, more preferably 0.05 to 1%, still more preferably 0.1 to 0.6%, still more preferably 0.15 to 0.45%, still more preferably 0.25 to 0.35% of the mass of the compound C. In the present invention, the stirring rate of the third stirring and mixing is preferably 20 to 5000rpm, more preferably 20 to 100rpm; the stirring time is preferably 30 to 60 minutes, more preferably 30 to 40 minutes; the vacuum degree is preferably 0.08 to 0.1MPa, more preferably 0.09 to 0.1MPa.
After the sizing material D is obtained, the sizing material D and the catalyst are subjected to fourth stirring and mixing under the vacuum condition to obtain the sizing material E. In the present invention, the catalyst is preferably a platinum catalyst, and the concentration of the active ingredient in the catalyst is preferably 100 to 10000ppm, more preferably 300 to 500ppm; the mass of the catalyst is preferably 0.02 to 3%, more preferably 0.05 to 2%, and even more preferably 0.1 to 1% of the mass of the sizing material C. In the present invention, the stirring rate of the fourth stirring and mixing is preferably 20 to 5000rpm, more preferably 20 to 100rpm; the stirring time is preferably 30 to 60 minutes, more preferably 30 to 40 minutes; the vacuum degree is preferably 0.08 to 0.1MPa, more preferably 0.09 to 0.1MPa. After the fourth stirring and mixing, the stirring is preferably stopped, and then the vacuum pumping is continued for 10min to obtain the sizing material E.
After the sizing material E is obtained, the sizing material E is sequentially pressed and cured to obtain the heat-conducting composite material. The pressing of the invention is preferably carried out on a calender, preferably the desired thickness of the thermally conductive composite material, the pressing conditions being such that conditions well known to those skilled in the art are employed. In the present invention, the curing preferably includes sequentially performing a first stage curing and a second stage curing. In the present invention, the temperature of the first stage curing is preferably 80 to 120 ℃, more preferably 90 to 100 ℃; the heat preservation time is preferably 15 to 60 minutes, more preferably 15 to 25 minutes; the temperature of the second stage curing is preferably 125-150 ℃, more preferably 125-135 ℃; the holding time is preferably 15 to 30 minutes, more preferably 15 to 20 minutes. The curing is preferably carried out in a tunnel oven.
The invention provides the heat conduction composite material prepared by the preparation method of the technical scheme, and the heat conduction coefficient of the heat conduction composite material is 2.0-15.0W/m.K, and can be 3.1135-14.2286W/m.K; the oil permeability is 0.5 to 2.0 percent, and can be particularly 0.56 to 1.78 percent; the breakdown voltage is 8.5-13.8 KV, and the tensile strength is 0.19-0.52 MPa.
The technical solutions of the present invention will be clearly and completely described in the following in connection with the embodiments of the present invention. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Examples 1 to 3
Adding vinyl silicone oil and a coupling agent into a planetary stirrer, and stirring and mixing for 5min at 30 rpm; then sequentially adding heat-conducting fillers with different particle sizes according to the particle sizes from small to large, and stirring and mixing for 10min under the condition of 20rpm to obtain a sizing material A;
Heating the sizing material A to 50 ℃, carrying out coupling reaction at the temperature of 50 ℃ for 30min, and maintaining the stirring speed at 20rpm in the heat preservation process to obtain sizing material B;
Heating the sizing material B to 120 ℃ and vacuumizing to the vacuum degree of 0.1MPa, carrying out kneading treatment at the temperature of 120 ℃ for 60min, maintaining the stirring speed at 20rpm in the heat preservation process, stopping stirring and vacuumizing after the kneading treatment is finished, and cooling to room temperature (25 ℃) to obtain sizing material C;
adding an inhibitor and a cross-linking agent into the sizing material C, vacuumizing to the vacuum degree of 0.1MPa, and stirring and mixing for 30min under the condition of 20rpm to obtain a sizing material D;
Adding a catalyst into the sizing material D, stirring and mixing for 30min under the conditions of stirring speed of 20rpm and vacuum degree of 0.1MPa, stopping stirring, and continuously vacuumizing for 10min to obtain a sizing material E;
the sizing material E is rolled on a calender and then is cured by a tunnel furnace, the curing comprises a first-stage curing and a second-stage curing which are sequentially carried out, the first-stage curing is kept for 15min at 100 ℃, and the second-stage curing is kept for 15min at 125 ℃ to obtain a heat-conducting gasket;
Wherein the viscosity of the vinyl silicone oil is 500cp, and the molar content of vinyl is 0.5%; the coupling agent is n-octyl trimethoxy silane; the heat conducting filler is micron-sized alumina, wherein the alumina with the grain diameter of 90-150 mu m accounts for 40wt%, the alumina with the grain diameter of 40-90 mu m accounts for 20wt%, the alumina with the grain diameter of 10-40 mu m accounts for 12wt%, the alumina with the grain diameter of 1-10 mu m accounts for 20wt%, and the alumina with the grain diameter of 0.1-1 mu m accounts for 8wt%; the inhibitor is ethynyl cyclohexanol; the cross-linking agent is hydrogen-containing silicone oil, the hydrogen-containing silicone oil comprises terminal hydrogen-containing silicone oil and side hydrogen-containing silicone oil, and the molar ratio of the terminal hydrogen-containing silicone oil to the side hydrogen-containing silicone oil is 0.15:1, wherein the hydrogen concentration of the hydrogen-containing silicone oil is 0.18wt%; the catalyst is a platinum catalyst, and the concentration of active ingredients in the platinum catalyst is 500ppm; the proportions of the raw materials used in each example are shown in Table 1.
Table 1 the proportions of the raw materials (unit: g) in examples 1 to 3
| Raw material type | Example 1 | Example 2 | Example 3 |
| Vinyl silicone oil | 100 | 100 | 100 |
| Inhibitors | 0.2 | 0.5 | 1 |
| Coupling agent | 10 | 15 | 24 |
| Crosslinking agent | 4 | 4 | 4 |
| Catalyst | 1 | 1 | 1 |
| Heat conductive filler | 1000 | 1500 | 2400 |
Examples 4 to 6
The heat conductive gaskets were prepared according to the methods of examples 1 to 3, respectively, except that aluminum nitride with the same particle size was used instead of part of the micron-sized alumina, and that the coupling agent used was cetyl siloxane; the proportions of the raw materials used in each example are shown in Table 2.
Table 2 raw material ratios (unit: g) in examples 4 to 6
Comparative examples 1 to 6
The raw material ratios of comparative examples 1 to 6 are the same as examples 1 to 6, respectively, except that the preparation method is as follows: mixing vinyl silicone oil, a coupling agent and a heat-conducting filler, heating to 120 ℃, vacuumizing to a vacuum degree of 0.1MPa, carrying out kneading treatment at 120 ℃ for 60min, maintaining the stirring speed at 20rpm in the heat-preserving process, stopping stirring and vacuumizing after the kneading treatment is finished, and cooling to room temperature (25 ℃) to obtain a sizing material C; a thermally conductive gasket was then prepared as in example 1.
Test example 1
The thermal pads prepared in examples 1 to 6 and comparative examples 1 to 6 were tested for performance by the following test method:
appearance state: visually observing the surface condition, and judging whether the surface has the phenomena of unevenness, air holes, powder falling and the like;
Thermal conductivity coefficient: ASTM D5470;
breakdown voltage: ASTM D149;
Tensile strength: ASTM D412;
Oil permeability: the detection is carried out according to a conventional method in the field, and comprises the following specific steps:
(1) Taking a round sample with the diameter of 30mm from a heat conduction gasket with the thickness of 2mm, weighing the net weight of a sample, and recording as G; (2) weighing the total weight of the four layers of glass fiber cloth, and recording as G1; (3) Covering 2 layers of glass fiber cloth on the upper and lower surfaces of a sample respectively, covering 3 layers of filter paper and 1 layer of high-temperature-resistant release film outside the glass fiber cloth respectively, placing the glass fiber cloth between two compression clamps, compressing the thickness of a heat conduction gasket by 50%, sleeving a 1mm thickness limiting gasket in a stud, and locking four screws through the thickness limiting gasket; (4) Placing the mixture into a precise oven preheated to 125 ℃, baking for 72 hours, and taking out; cooling in a dryer, standing for 2h, removing the oil seepage tooling, carefully taking down filter paper, weighing and recording the total weight of the sample and the glass fiber cloth, and recording as G2; (5) calculating according to a calculation formula: oil permeability: r% = [1- (G2-G1)/G ]. Times.100%.
The test results are shown in Table 3.
Table 3 results of performance test of the heat conductive gaskets prepared in examples 1 to 6 and comparative examples 1 to 6
As can be seen from Table 3, the continuous process combining the filler modification process and the high-temperature kneading process of the sizing material is not only suitable for a system completely adopting aluminum oxide as the heat-conducting filler, but also suitable for a system adding aluminum nitride as the heat-conducting filler, and finally the heat-conducting gasket with excellent performances in all aspects is prepared.
The performance test results of the heat-conducting gaskets prepared in comparative examples 1 to 6 and comparative examples 1 to 6 show that the continuous process combining the filler modification process and the high-temperature kneading process of the sizing material has obvious advantages compared with the traditional process of directly adding the coupling agent. The first stage (low temperature stage) of sizing material treatment is a process of coupling reaction between the coupling agent and the heat conducting filler to form chemical bonds, and the coupling reaction at the stage ensures that the heat conducting filler and the resin matrix have better compatibility, so that the heat conducting filler can be better dispersed in the resin matrix, the sizing material state is improved, meanwhile, the interface thermal resistance among heat conducting filler particles is reduced, and the heat conducting capability is improved. The second stage (high temperature stage) of sizing material treatment is a process of removing the superfluous coupling agent which does not participate in the coupling reaction, if the residual coupling agent in the system is not removed, the residual coupling agent can volatilize in the high temperature curing process, thereby causing defects of products such as air holes, peeling and the like and affecting various performances of the products; in addition, residual coupling agent escapes after curing is finished, so that the oil permeability is increased, the ageing performance is reduced, and the product is adversely affected. Therefore, two stages in a continuous process combining a filler modification process and a sizing material high-temperature kneading process have a critical influence on the performance of the finally prepared heat-conducting gasket, and the heat-conducting gasket prepared by the method has the advantages of higher heat conductivity, lower oil permeability, excellent mechanical and electrical properties and stable aging resistance.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (10)
1. A preparation method of the heat-conducting composite material comprises the following steps:
The vinyl silicone oil and the coupling agent are subjected to first stirring and mixing, and the obtained mixture and the heat conducting filler are subjected to second stirring and mixing to obtain a sizing material A;
heating the sizing material A under the stirring condition to perform coupling reaction to obtain a sizing material B;
heating the sizing material B under the stirring condition to carry out vacuum kneading treatment to obtain sizing material C;
Thirdly stirring and mixing the sizing material C, the inhibitor and the cross-linking agent under the vacuum condition to obtain a sizing material D;
stirring and mixing the sizing material D and the catalyst for the fourth time under the vacuum condition to obtain a sizing material E;
and (3) sequentially pressing and curing the sizing material E to obtain the heat-conducting composite material.
2. The preparation method according to claim 1, wherein the viscosity of the vinyl silicone oil is 100-5000 cp, and the molar content of vinyl in the vinyl silicone oil is 0.3-1.5%;
the coupling agent comprises one or more of acetoxyl propyl trimethoxy silane, n-octyl trimethoxy silane, dodecyl siloxane, hexadecyl siloxane, octadecyl siloxane, phthalate and aluminate;
The heat conducting filler comprises one or more of aluminum oxide, zinc oxide, aluminum nitride and diamond, and the mass fraction of the aluminum oxide in the heat conducting filler is 50-100%.
3. The preparation method according to claim 1 or 2, wherein the mass ratio of the vinyl silicone oil to the heat conductive filler is 1: 10-40% of coupling agent, wherein the mass of the coupling agent is 0.1-2.0% of the mass of the heat conducting filler.
4. The method according to claim 1, wherein the stirring rate of the first stirring and the second stirring is 20 to 1000rpm independently and the stirring time is 5 to 60min independently.
5. The preparation method according to claim 1, wherein the coupling reaction is carried out at a temperature of 40 to 100 ℃ for 30 to 90 minutes with a stirring rate of 20 to 1000rpm.
6. The method according to claim 1, wherein the vacuum kneading treatment is carried out at a temperature of 120 to 170 ℃ for 60 to 120 minutes at a stirring rate of 20 to 1000rpm.
7. The preparation method according to claim 1, wherein the inhibitor is ethynyl cyclohexanol, and the mass of the inhibitor is 0.01-0.5% of the mass of the sizing material C;
The cross-linking agent is hydrogen-containing silicone oil, and the mass of the cross-linking agent is 0.01-1.5% of the mass of the sizing material C;
The catalyst is a platinum catalyst, and the concentration of active ingredients in the catalyst is 100-10000 ppm.
8. The method according to claim 1, wherein the stirring rate of the third stirring and the fourth stirring is 20-5000 rpm, and the stirring time is 30-60min.
9. The method of claim 1, wherein the curing comprises sequentially performing a first stage cure and a second stage cure; the curing temperature in the first stage is 80-120 ℃, and the heat preservation time is 15-60 min; the curing temperature in the second stage is 125-150 ℃, and the heat preservation time is 15-30 min.
10. The heat conductive composite material prepared by the preparation method of any one of claims 1 to 9, wherein the heat conductivity coefficient is 2.0-15.0W/m.K, and the oil permeability is 0.5-2.0%.
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