Double-sided anisotropic heat conduction / heat insulation bifunctional film and preparation method thereof

Abstract

The invention discloses a double-faced anisotropic heat conduction / heat insulation bifunctional membrane and a preparation method thereof.The bifunctional membrane comprises a laminated filter disc and functional slurry laid on the laminated filter disc, the aperture of filter holes of the laminated filter disc is gradually reduced from top to bottom, and the functional slurry is prepared from, by weight, 10-30 parts of functional slurry and 10-30 parts of functional slurry. Comprising the following components in parts by weight: 10-50 parts of heat-conducting powder, 10-50 parts of heat-insulating powder, 40-80 parts of a film-forming substance, 40-80 parts of water and 20-30 parts of an auxiliary agent, wherein the particle size of the heat-conducting powder is 1.3-2.6 microns, and the heat conductivity coefficient of the heat-conducting powder is greater than 100W / (m.K); the particle size of the heat insulation powder is 13-100 microns, and the heat conductivity coefficient of the heat insulation powder is smaller than 0.03 W / (m.K). The heat conduction / heat insulation bifunctional film can realize comprehensive heat management of heat dissipation / heat insulation in a narrow space.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal management materials, and in particular to a double-sided anisotropic thermally conductive / insulating dual-functional film and a preparation method thereof. Background Art

[0002] With the upgrading of smart electronic products, smart phones, computers, etc. have gradually become an indispensable part of daily life. However, with the popularization of 5G and the enhancement of equipment configuration, the power consumption and battery heat generation of electronic products are getting bigger and bigger. Considering the product size, the heat insulation and heat dissipation space reserved in the product is extremely limited. Usually, a film material with heat insulation and heat dissipation function is attached to the surface of the battery cell. In order to meet the needs of battery thermal management, the membrane material must not only quickly conduct the heat generated by the battery, but also provide good heat insulation protection for the battery. In the prior art, membrane materials with both heat conduction and heat insulation functions are usually realized by stacking a layer of heat insulation material and a layer of heat conductive material in sequence. However, this method not only requires more space, but also poor material matching can easily cause material peeling and falling off, thus affecting the overall effect. Summary of the invention

[0003] In order to overcome the above-mentioned shortcomings, the purpose of the present invention is to provide a double-sided anisotropic thermal conductive / insulating dual-functional film and a preparation method thereof, so as to realize the comprehensive thermal management of heat dissipation / insulation in a small space.

[0004] In order to achieve the above purpose, one of the technical solutions adopted by the present invention is: a thermally conductive / insulating dual-functional membrane, comprising a laminated filter and a functional slurry laid on the laminated filter, the filter pore diameter of the laminated filter gradually decreases from top to bottom, and the functional slurry comprises, by weight, 10 to 50 parts of thermally conductive powder, 10 to 50 parts of thermally insulating powder, 40 to 80 parts of film-forming material, 40 to 80 parts of water, and 20 to 30 parts of additives; wherein the particle size of the thermally conductive powder is 1.3 to 2.6 μm, and its thermal conductivity is greater than 100 W / (m·K); the particle size of the thermally insulating powder is 13 to 100 μm, and its thermal conductivity is less than 0.03 W / (m·K).

[0005] The beneficial effects of the heat-conducting / heat-insulating dual-function film of the present invention are: The functional slurry can have both thermal conductivity and thermal insulation functions by combining high thermal conductivity, small particle size (high bulk density) thermal conductive powder with low thermal conductivity, large particle size (low bulk density) thermal insulation powder; the combination of film-forming substances, water and additives can facilitate the mixing of thermal conductive powder and thermal insulation powder in the slurry, thereby facilitating the flow of the slurry from the laminated filter disc; on the laminated filter disc, the difference in particle size between the thermal insulation powder and the thermal conductive powder is utilized, and the difference in filter pore size of the laminated filter disc is combined, so that the thermal insulation powder with large particle size can be located on the upper layer of the thermal conductive powder with small particle size, thereby facilitating the flow of the slurry from the laminated filter disc; on the laminated filter disc, the difference in particle size between the thermal insulation powder and the thermal conductive powder is utilized, and the difference in filter pore size of the laminated filter disc is combined, so that the thermal insulation powder with large particle size can be located on the upper layer of the thermal conductive powder with small particle size, thereby The dual-functional membrane can utilize the high thermal conductivity of the thermal conductive powder to dissipate the heat of the product on one side, and utilize the high thermal insulation performance of the thermal insulation powder to block the heat from radiating outward on the other side, thereby realizing comprehensive thermal management of the product surface; and because the thermal conductive powder and the thermal insulation powder are directly mixed in the slurry and then laid on the laminated filter, compared with the stacked laying of thermal conductive films and thermal insulation films in the prior art, it can not only improve the structural strength, but also effectively reduce the overall film thickness of the dual-functional membrane, thereby realizing the heat dissipation / thermal insulation problem in a small space.

[0006] Furthermore, the thermally conductive powder is at least one of metal (such as gold, silver, copper, aluminum, tungsten, zinc, etc.), diamond, aluminum nitride, silicon carbide, and graphite. Graphite is preferred. Graphite has high thermal conductivity in the XY direction and low thermal conductivity in the Z direction. Using graphite as a thermally conductive powder can facilitate rapid heat dispersion.

[0007] Furthermore, the thermal insulation powder is at least one of aerogel, aerosil, and hollow glass microspheres. Preferably, the aerogel is a surface hydrophobic aerogel with a bulk density of 25-100 g / cm 3 .

[0008] Furthermore, the film-forming substance is at least one of polyurethane emulsion, modified polyurethane emulsion, acrylic emulsion, epoxy emulsion, and silicone emulsion.

[0009] Specifically, the film-forming substance is a nano-scale polyurethane emulsion or a modified polyester emulsion. The nano-scale film-forming substance is more conducive to the dispersion of the slurry, so that each component is dispersed more evenly. Furthermore, the modified polyurethane emulsion is a fluorine-modified polyurethane emulsion, and the thermal insulation performance of the film-forming substance is improved by grafting and modifying the polyurethane emulsion.

[0010] Furthermore, the auxiliary agent includes at least one of a dispersant, a wetting agent, a defoaming agent, a leveling agent, a thickener, a multifunctional auxiliary agent, a film-forming auxiliary agent, a flame retardant, and a bactericide and mildew preventer.

[0011] Furthermore, the additives include 1 to 5 parts of dispersant, 1 to 5 parts of wetting agent, 1 to 10 parts of defoaming agent, 5 to 10 parts of leveling agent, 1 to 10 parts of thickener, 1 to 5 parts of multifunctional additive, 1 to 10 parts of film-forming additive, 10 to 15 parts of flame retardant, and 1 to 5 parts of bactericide and mildewicide.

[0012] The second technical solution adopted by the present invention is: a method for preparing a heat-conducting / heat-insulating dual-functional film, comprising the following steps: (1) Add thermal conductive powder, thermal insulation powder, film-forming material, water and additives into a high-speed disperser for dispersion to obtain a functional slurry; (2) Stacking filter membranes of different pore sizes from top to bottom in descending order of pore size to form a laminated filter; (3) The functional slurry is evenly spread on the filter membrane of the uppermost layer of the laminated filter disc, and then high-frequency vibration and low negative pressure filtration are performed until the filter membrane of the lowermost layer of the laminated filter disc is covered with the functional slurry to form a wet filter cake; (4) The wet filter cake is dried under constant pressure to obtain a dual-functional membrane.

[0013] The beneficial effects of the preparation method of the heat-conducting / heat-insulating dual-functional film of the present invention are: Through the configuration of step (1), the thermal conductive powder and the thermal insulating powder can be integrated into the functional slurry, so as to facilitate the subsequent integrated film formation of the functional slurry; through the configuration of step (2), the laminated filter can perform layered screening on the functional slurry, and then through the high-frequency vibration and low-negative-pressure filtration of step (3), the functional slurry is layered on the laminated filter, so that the thermal insulating powder is screened on the upper part of the laminated filter, and the thermal conductive powder is screened on the lower part of the laminated filter; finally, through step (4), an integrated dual-functional membrane is formed.

[0014] Since the thermally conductive powder and thermally insulating powder are dispersed in the functional slurry, and the functional slurry is directly laid on the laminated filter disc, the film-forming property of the wet filter cake can be not affected. The particle differences of the thermally conductive powder and thermally insulating powder and the pore size differences of the laminated filter disc can be utilized to make the wet filter cake present the phenomenon of stratification of the thermally conductive powder and thermally insulating powder, thereby achieving the effect of one-piece molding of the dual-functional membrane with both thermal conductivity and thermal insulation properties.

[0015] Furthermore, in step (2), the thickness of the filter membrane is 2-5 μm, the total thickness of the laminated filter is 10-20 μm, and the pore size of the filter membrane is one of 0.2 μm, 0.5 μm, 1 μm, 2 μm, 5 μm, 10 μm, 20 μm, 50 μm, and 80 μm.

[0016] Furthermore, in step (4), the constant pressure is 0.02-0.5 MPa, and the thickness of the bifunctional membrane is 50-1000 μm. DETAILED DESCRIPTION

[0017] The preferred embodiments of the present invention are described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more explicit definition of the protection scope of the present invention. It should be noted that the following embodiments are for a better understanding of the present invention, are not limited to the best embodiments, and do not limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0018] It should be noted that, in the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0019] In addition, if the specific experimental steps or conditions are not specified in the examples, the operations or conditions of the conventional experimental steps described in the literature in the art can be carried out. The numerical ranges shown by "~" in the examples indicate the ranges containing the values ​​recorded before and after "~" as the minimum and maximum values, respectively. If the manufacturers of the reagents or instruments are not specified, they are all conventional reagent products that can be obtained commercially.

[0020] The invention discloses a double-sided anisotropic heat-conducting / insulating dual-functional membrane, comprising a laminated filter and a functional slurry laid on the laminated filter. The filter hole diameter of the laminated filter gradually decreases from top to bottom. The functional slurry comprises 10 to 50 parts of heat-conducting powder, 10 to 50 parts of heat-insulating powder, 40 to 80 parts of film-forming material, 40 to 80 parts of water, and 20 to 30 parts of additives by weight. The particle size of the heat-conducting powder is 1.3 to 2.6 μm, the fineness is 5000 to 10000 mesh, and the thermal conductivity is greater than 100 W / (m·K). The particle size of the heat-insulating powder is 13 to 100 μm, the fineness is 150 to 1000 mesh, and the thermal conductivity is less than 0.03 W / (m·K).

[0021] The functional slurry can have both thermal conductivity and thermal insulation functions by combining high thermal conductivity, small particle size thermal conductive powder with low thermal conductivity, large particle size thermal insulation powder; the combination of film-forming substances, water and additives can facilitate the mixing of thermal conductive powder and thermal insulation powder in the slurry, thereby facilitating the flow of the slurry from the laminated filter disc; on the laminated filter disc, the difference in particle size between the thermal insulation powder and the thermal conductive powder is utilized, and the difference in filter pore size of the laminated filter disc is combined, so that the large particle size thermal insulation powder can be located on the upper layer of the small particle size thermal conductive powder, thereby enabling the dual-functional membrane to On one side, the high thermal conductivity of the thermal conductive powder is used to dissipate the heat of the product itself, and on the other side, the high thermal insulation performance of the thermal insulation powder is used to block the heat from radiating outward, thereby achieving comprehensive thermal management of the product surface; and because the thermal conductive powder and the thermal insulation powder are directly mixed in the slurry and then laid on the laminated filter, compared with the stacking of thermal conductive films and thermal insulation films in the prior art, it can not only improve the structural strength, but also effectively reduce the overall film thickness of the dual-functional film, thereby achieving the heat dissipation / thermal insulation problem in a small space.

[0022] In some embodiments, the thermally conductive powder is at least one of metal, diamond, aluminum nitride, silicon carbide, and graphite. Graphite is preferred. Graphite has high thermal conductivity in the XY direction and low thermal conductivity in the Z direction. Using graphite as a thermally conductive powder can facilitate rapid heat dispersion. However, due to the limited internal space of electronic products, while dispersing heat, it is possible to cause the temperature of heat-sensitive components near the heat source to be too high. Therefore, it is also necessary to use materials with good thermal insulation effects.

[0023] In some embodiments, the thermal insulation powder is at least one of aerogel, aerosil, and hollow glass microspheres. Preferably, the aerogel is a surface hydrophobic aerogel with a bulk density of 25 to 100 g / cm 3 The nano-scale porous structure of aerogel can effectively isolate heat conduction and heat convection.

[0024] In order to ensure the stratification effect of the thermal conductive powder and the thermal insulating powder in the dual-functional membrane, in some embodiments, the density ratio of the thermal conductive powder to the thermal insulating powder is 30:1, and the particle size ratio of the thermal conductive powder to the thermal insulating powder is 1:5 to 60. This makes the thermal conductive powder and the thermal insulating powder have a high density difference and a high particle size difference, which is conducive to the stratification of the functional slurry on the laminated filter.

[0025] In some embodiments, the film-forming substance is at least one of polyurethane emulsion, modified polyurethane emulsion, acrylic emulsion, epoxy emulsion, and silicone emulsion. Preferably, it is nano-scale polyurethane emulsion or modified polyester emulsion. Nano-scale film-forming substances are more conducive to the dispersion of the slurry, making the dispersion of each component more uniform. Furthermore, the modified polyurethane emulsion is a fluorine-modified polyurethane emulsion, and the thermal insulation performance of the film-forming substance is improved by grafting and modifying the polyurethane emulsion.

[0026] In some embodiments, the additive includes at least one of a dispersant, a wetting agent, a defoaming agent, a leveling agent, a thickener, a multifunctional additive, a film-forming additive, a flame retardant, and a bactericide and mildew preventer. Specifically, the dispersant is at least one of 5040 dispersant, sodium tripolyphosphate, sodium tetrapolyphosphate and sodium hexapolyphosphate, the wetting agent is at least one of 740 wetting agent, polyoxyethylene fatty acid ester, polyoxyethylene alkylphenyl ether, the defoaming agent is at least one of triphenyl phosphate and DF-071 defoaming agent, the leveling agent is cellulose acetate butyrate, the thickener is at least one of 820 thickener, TT-935 thickener, hydroxymethyl cellulose, and hydroxyethyl cellulose, the multifunctional auxiliary agent is at least one of AMP-95, HT96, and CD90, the film-forming auxiliary agent is at least one of ethylene glycol ethyl ether, ethylene glycol butyl ether, ethylene glycol, and propylene glycol, the flame retardant is at least one of brominated flame retardants, nitrogen flame retardants, and red phosphorus, and the bactericidal and mildew-proofing agent is at least one of MA-21 mildew-proofing agent, BC-652 mildew-proofing agent, and phenol.

[0027] Exemplarily, the additives include 1 to 5 parts of dispersant, 1 to 5 parts of wetting agent, 1 to 10 parts of defoaming agent, 5 to 10 parts of leveling agent, 1 to 10 parts of thickener, 1 to 5 parts of multifunctional additive, 1 to 10 parts of film-forming additive, 10 to 15 parts of flame retardant, and 1 to 5 parts of bactericide and mildewicide.

[0028] The present invention also provides a method for preparing a double-sided anisotropic thermally conductive / insulating dual-functional film, comprising the following steps: (1) Add thermal conductive powder, thermal insulation powder, film-forming material, water and additives into a high-speed disperser for dispersion to obtain a functional slurry; wherein the speed of the high-speed disperser is 500-2000 rpm and the dispersion time is 5-30 min; (2) stacking filter membranes of different pore sizes from top to bottom in descending order of pore size to form a laminated filter disc; wherein the thickness of the filter membrane is 2 to 5 μm, and the total thickness of the laminated filter disc is 10 to 20 μm; (3) The functional slurry is evenly spread on the filter membrane of the uppermost layer of the laminated filter disc, and then high-frequency vibration and low negative pressure filtration are performed until the filter membrane of the lowermost layer of the laminated filter disc is covered with the functional slurry to form a wet filter cake; (4) The wet filter cake is dried under a constant pressure to obtain a bifunctional membrane, wherein the constant pressure is 0.02-0.5 MPa and the thickness of the bifunctional membrane is 50-1000 μm.

[0029] In the preparation method of the present invention, through the setting of step (1), the thermal conductive powder and the thermal insulating powder can be integrated into the functional slurry, so as to facilitate the subsequent integrated film formation of the functional slurry; through the setting of step (2), the laminated filter can perform layered screening on the functional slurry, and then through the high-frequency vibration and low-negative pressure filtration in step (3), the functional slurry is layered on the laminated filter, so that the thermal insulating powder is screened on the upper part of the laminated filter, and the thermal conductive powder is screened on the lower part of the laminated filter; finally, through step (4), an integrated dual-functional membrane is formed.

[0030] Furthermore, in step (2), the pore size of the filter membrane is one of 0.2 μm, 0.5 μm, 1 μm, 2 μm, 5 μm, 10 μm, 20 μm, 50 μm, and 80 μm.

[0031] In addition, by utilizing the density difference between the thermal conductive powder and the thermal insulation powder, the following method can be used to prepare a dual-functional membrane. The specific steps are as follows: (1) Add thermal conductive powder, thermal insulation powder, film-forming material, water and additives into a high-speed disperser for dispersion to obtain a functional slurry; wherein the speed of the high-speed disperser is 500-2000 rpm and the dispersion time is 5-30 min; (2) Pour the functional slurry into a centrifuge tube with a small hole at the bottom. At this time, the small hole at the bottom is in a closed state. Then put the centrifuge tube into a centrifuge for centrifugation. The speed of the centrifuge is 500-1000 rpm. The centrifugation time is 1-10 min. The functional slurry is controlled to form a continuous gradient band of different densities before the solid-liquid separation phenomenon occurs. (3) Open the small hole at the bottom of the centrifuge tube to allow the functional slurry to flow slowly and evenly into the mold at a flow rate of 1-5 ml / s; after drying, the dual-functional membrane is obtained.

[0032] This method requires that a lower centrifugal speed be used during the centrifugation process so that the substances in the functional slurry can form a continuous gradient band according to the density, and then the functional slurry is spread in the mold in sequence according to different densities through small holes to form a layered dual-functional membrane.

[0033] Example 1 The bifunctional membrane is prepared by the following steps, and the specific steps are: (1) Add 30 parts of thermal conductive powder, 30 parts of thermal insulating powder, 80 parts of film-forming substance, 50 parts of water and 30 parts of additives into a high-speed disperser and disperse at a speed of 1500 rpm for 20 minutes to obtain a functional slurry; wherein the thermal conductive powder is 5000 mesh (particle size is 2.6 μm) graphite, the thermal insulating powder is 1000 mesh (particle size is 13 μm) aerogel powder, the film-forming substance is a polyurethane emulsion with an emulsion particle size of less than 100 nm, and the additives are 2 parts of 5040 dispersant, 3 parts of 740 wetting agent, 5 parts of DF-071 defoaming agent, 3 parts of cellulose acetate butyrate, 1 part of 820 thickener, 2 parts of AMP-95 multifunctional additive, 3 parts of ethylene glycol ethyl ether, 10 parts of red phosphorus and 1 part of MA-21 mildew inhibitor.

[0034] (2) Filter membranes with pore sizes of 0.5 μm, 1 μm, 2 μm, 5 μm, and 10 μm and a thickness of 2 μm are stacked from top to bottom in descending order of pore size to form a laminated filter. The total thickness of the laminated filter is 10 μm.

[0035] (3) The functional slurry is evenly spread on the filter membrane of the top layer of the laminated filter disc, and then high-frequency vibration and low negative pressure filtration are performed until the filter membrane of the bottom layer of the laminated filter disc is covered with the slurry to form a wet filter cake.

[0036] (4) The wet filter cake was taken out and dried at a constant pressure of 0.03 MPa to obtain a bifunctional membrane with a thickness of 200 μm.

[0037] Example 2 The difference between this embodiment and embodiment 1 is that the thermal conductive powder material is diamond, and the thermal insulating powder material is gas silicon powder.

[0038] Example 3 The difference between this embodiment and embodiment 1 is that the number of portions of thermal conductive powder is 20 portions, and the number of portions of thermal insulating powder is 40 portions.

[0039] Example 4 The difference between this embodiment and embodiment 1 is that the fineness of the thermal conductive powder is 10000 mesh, and the fineness of the thermal insulation powder is 150 mesh; the laminated filter is composed of 2μm thick filter membranes with pore sizes of 0.2μm, 0.5μm, 1μm, 5μm, 10μm, 20μm, 50μm, and 80μm, and the total thickness of the laminated filter is 16μm.

[0040] Example 5 The functional membrane is prepared by the following steps, and the specific steps are: (1) Add 30 parts of thermal conductive powder, 30 parts of thermal insulating powder, 80 parts of film-forming substance, 50 parts of water and 30 parts of additives into a high-speed disperser and disperse at a speed of 1500 rpm for 20 minutes to obtain a functional slurry; wherein the thermal conductive powder is 5000 mesh (particle size is 2.6 μm) graphite, the thermal insulating powder is 1000 mesh (particle size is 13 μm) aerogel powder, the film-forming substance is a polyurethane emulsion with an emulsion particle size of less than 100 nm, and the additives are 2 parts of 5040 dispersant, 3 parts of 740 wetting agent, 5 parts of DF-071 defoaming agent, 3 parts of cellulose acetate butyrate, 1 part of 820 thickener, 2 parts of AMP-95 multifunctional additive, 3 parts of ethylene glycol ethyl ether, 10 parts of red phosphorus and 1 part of MA-21 mildew inhibitor.

[0041] (2) Pour 10 ml of the functional slurry into a centrifuge tube with a small hole at the bottom. At this time, the small hole at the bottom is in a closed state. Then put the centrifuge tube into a centrifuge for centrifugation. The speed of the centrifuge is 1000 rpm and the centrifugation time is 10 min. (3) Open the small hole at the bottom of the centrifuge tube to allow the functional slurry to flow slowly and evenly into the mold (mold size is 10 cm*25 cm) at a rate of 1 ml / s. After drying, a dual-functional membrane with a film thickness of 200 μm is obtained.

[0042] Example 6 The difference between this embodiment and embodiment 5 is that the thermal conductive powder is copper powder, the centrifuge speed is 500 rpm, and the centrifugation time is 5 minutes.

[0043] Example 7 The difference between this embodiment and embodiment 1 is that in step (4), the constant pressure is 0.06 MPa and the film thickness is 100 μm.

[0044] Example 8 The difference between this embodiment and embodiment 5 is that the mold size is 20 cm*25 cm and the film thickness is 100 μm.

[0045] Comparative Example 1 The difference between this comparative example and Example 1 is that no thermal insulation powder is added to the functional slurry.

[0046] Comparative Example 2 The difference between this comparative example and Example 1 is that no thermal conductive powder is added to the functional slurry.

[0047] Test example The bifunctional membranes prepared in Examples 1-8 and Comparative Examples 1-2 were subjected to performance testing, and the testing method was as follows: at room temperature (21°C), one side of the bifunctional membrane (hereinafter referred to as the "front side of the membrane") was completely attached to a heat source, and the other side (hereinafter referred to as the "back side of the membrane") was completely exposed to the air, and the temperature of the heat source was kept constant at 90°C; then the temperatures of both sides of the bifunctional membrane were tested every 1 minute, and the test results are shown in Table 1.

[0048] Table 1 Test results of Examples 1-8 and Comparative Examples 1-2

[0049] From Table 1 we can see that: 1. According to the test results of Examples 1-4, the dual-function film of the present invention has good thermal conductivity on the side close to the heat source, and at the same time, has good thermal insulation on the side away from the heat source; among them, compared with Example 1, Example 3 reduces the amount of thermal conductive powder and increases the amount of thermal insulation powder, resulting in a slowdown in the thermal conductivity rate of the front side of the film of Example 3, while the thermal insulation effect of the back side of the film is better.

[0050] 2. According to the test results of Examples 1 and 5, the thermal conductivity and thermal insulation properties of the bifunctional membrane prepared by the preparation method of Example 1 are better than those of the bifunctional membrane prepared by the preparation method of Example 5. The reason is that the centrifugal separation operation in Examples 5 and 6 is difficult to control, and the outflow process of the functional slurry may also cause the components to mix again, thereby affecting the final stratification effect of the bifunctional membrane.

[0051] 3. According to the test results of Examples 5 and 6, when the bifunctional membrane is prepared by the preparation methods of Examples 5 and 6, the difference in centrifugal operation will affect the stratification effect of the functional slurry, and further affect the final comprehensive performance of the bifunctional membrane. 4. According to the test results of Examples 1 and 7 or Examples 5 and 8, it can be seen that as the film thickness decreases, the thermal conductivity of the bifunctional film does not change significantly, but the thermal insulation performance decreases significantly.

[0052] 5. According to the test results of Example 1 and Comparative Example 1, it can be seen that: compared with the traditional thermal conductive film, the thermal conductivity of the dual-functional film of the present invention is not significantly different, but the thermal insulation performance is significantly improved.

[0053] 6. According to the test results of Example 1 and Comparative Example 2, it can be seen that the thermal conductivity and thermal insulation properties of the dual-functional film of the present invention are improved compared with the traditional thermal insulation film.

[0054] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A double-sided anisotropic thermal conductive / insulating dual-function film, characterized in that: It comprises a laminated filter disc and a functional slurry laid on the laminated filter disc, wherein the filter hole diameter of the laminated filter disc gradually decreases from top to bottom, and the functional slurry comprises, by weight, 10 to 50 parts of thermal conductive powder, 10 to 50 parts of thermal insulating powder, 40 to 80 parts of film-forming material, 40 to 80 parts of water, and 20 to 30 parts of additives; wherein the particle size of the thermal conductive powder is 1.3 to 2.6 μm, and its thermal conductivity is greater than 100 W / (m·K); the particle size of the thermal insulating powder is 13 to 100 μm, and its thermal conductivity is less than 0.03 W / (m·K).

2. A double-sided anisotropic thermal conductive / insulating dual-function film according to claim 1, characterized in that: The thermally conductive powder is at least one of metal, diamond, aluminum nitride, silicon carbide and graphite.

3. A double-sided anisotropic thermal conductive / insulating dual-function film according to claim 1, characterized in that: The thermal insulation powder is at least one of aerogel, aerosil, and hollow glass microspheres.

4. The double-sided anisotropic thermal conductive / insulating dual-function film according to claim 1, characterized in that: The film-forming substance is at least one of polyurethane emulsion, modified polyurethane emulsion, acrylic emulsion, modified acrylic emulsion, epoxy emulsion and silicone emulsion.

5. A double-sided anisotropic thermal conductive / insulating dual-function film according to claim 4, characterized in that: The film-forming substance is nano-scale polyurethane emulsion or modified polyurethane emulsion.

6. The double-sided anisotropic thermal conductive / insulating dual-function film according to claim 1, characterized in that: The auxiliary agent includes at least one of a dispersant, a wetting agent, a defoaming agent, a leveling agent, a thickener, a multifunctional auxiliary agent, a film-forming auxiliary agent, a flame retardant, and a bactericide and mildew preventer.

7. A double-sided anisotropic thermal conductive / insulating dual-function film according to claim 6, characterized in that: The additives include 1 to 5 parts of a dispersant, 1 to 5 parts of a wetting agent, 1 to 10 parts of a defoaming agent, 5 to 10 parts of a leveling agent, 1 to 10 parts of a thickener, 1 to 5 parts of a multifunctional additive, 1 to 10 parts of a film-forming additive, 10 to 15 parts of a flame retardant, and 1 to 5 parts of a bactericide and mildew preventer.

8. A method for preparing a double-sided anisotropic thermal conductive / insulating dual-functional film, characterized in that: The steps include: (1) Add thermal conductive powder, thermal insulation powder, film-forming material, water and additives into a high-speed disperser for dispersion to obtain a functional slurry; (2) Stacking filter membranes of different pore sizes from top to bottom in descending order of pore size to form a laminated filter; (3) The functional slurry is evenly spread on the filter membrane of the uppermost layer of the laminated filter disc, and then high-frequency vibration and low negative pressure filtration are performed until the filter membrane of the lowermost layer of the laminated filter disc is covered with the functional slurry to form a wet filter cake; (4) The wet filter cake is dried under constant pressure to obtain a dual-functional membrane.

9. The method for preparing a double-sided anisotropic thermal conductive / insulating dual-functional film according to claim 8, characterized in that: In step (2), the thickness of the filter membrane is 2-5 μm, the total thickness of the laminated filter is 10-20 μm; the pore size of the filter membrane is one of 0.2 μm, 0.5 μm, 1 μm, 2 μm, 5 μm, 10 μm, 20 μm, 50 μm, and 80 μm.

10. The method for preparing a double-sided anisotropic thermal conductive / insulating dual-functional film according to claim 8, characterized in that: In step (4), the constant pressure is 0.02-0.5 MPa, and the thickness of the bifunctional membrane is 50-1000 μm.

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