CN114835861A - Low-dielectric high-thermal-conductivity composite film and preparation method thereof - Google Patents

Low-dielectric high-thermal-conductivity composite film and preparation method thereof Download PDF

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CN114835861A
CN114835861A CN202210507740.9A CN202210507740A CN114835861A CN 114835861 A CN114835861 A CN 114835861A CN 202210507740 A CN202210507740 A CN 202210507740A CN 114835861 A CN114835861 A CN 114835861A
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composite film
boron nitride
parts
low dielectric
thermal conductivity
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杨应彬
任泽明
王号
廖骁飞
吴攀
贺超
张松
李宏高
任泽永
潘锋芳
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Guangdong Suqun Industrial Co ltd
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    • C08F283/00—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G
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Abstract

The application relates to the technical field of composite films, in particular to a composite film with low dielectric constant and high thermal conductivity and a preparation method thereof. The composition comprises the following raw materials in parts by weight: 50-70 parts of waterborne polyurethane, 5-8 parts of acrylic acid, 12-18 parts of heat-conducting filler, 0.3-0.5 part of dispersing agent, 0.2-0.3 part of defoaming agent, 0.05-0.1 part of curing agent and 20-30 parts of water. The composite film has a good heat conduction effect and low dielectric.

Description

Low-dielectric high-thermal-conductivity composite film and preparation method thereof
Technical Field
The application relates to the technical field of composite films, in particular to a composite film with low dielectric constant and high thermal conductivity and a preparation method thereof.
Background
The composite film mainly refers to a film obtained by compounding two or more materials, and at present, the composite film has heat conduction, is mainly used for heat dissipation of electronic products, such as heat dissipation of mobile phones, computers, new energy automobiles and the like, and commonly used composite films mainly comprise metal heat dissipation types, graphite types, insulating heat dissipation types and the like, wherein the metal heat dissipation types comprise heat dissipation copper foils, heat dissipation aluminum foils and the like, the graphite types comprise natural graphite sheets, artificial graphite sheets, graphene films and the like, and the metal types and the graphite types have good heat dissipation effects, but have high dielectric properties and are easy to conduct electricity, so that the possibility of electric shock is easy to occur when the electronic products are used for heat dissipation; furthermore, most of electronic products choose heat dissipation films of the insulating and heat conducting type, but with the technological progress, people's demands are increased, the quality requirements for articles are also increased, and the electronic products are updated and upgraded day by day, for example, common mobile phones or computers are developed with the internet, the application software of mobile phones is increased, and further the generated heat is increased, so that the existing insulating and heat conducting type heat dissipation materials cannot be demanded, and therefore, the research of new heat dissipation materials is imperative.
Disclosure of Invention
In order to obtain a material with high thermal conductivity and low dielectric constant, the application provides a composite film with low dielectric constant and high thermal conductivity and a preparation method thereof.
In a first aspect, the present application provides a low dielectric high thermal conductive composite film, which is prepared from the following raw materials in parts by weight:
aqueous polyurethane: 50-70 parts of
Acrylic acid: 5-8 parts of
Heat-conducting filler: 12 to 18 portions of
Dispersing agent: 0.3 to 0.5 portion
Defoaming agent: 0.2 to 0.3 portion
Curing agent: 0.05 to 0.1 portion
Water: 20-30 parts.
The raw materials and the weight parts of the raw materials are in a better range, and the prepared composite film has the advantages of low dielectric constant, insulation and high heat conduction, so that when the composite film is used for heat dissipation of electronic products, the heat dissipation effect can be improved, and the possibility of electric shock is reduced.
Generally, a composite film made of waterborne polyurethane is generally coated, cured and then formed into a composite film. The waterborne polyurethane has the advantages of no pollution, safety, reliability, excellent mechanical property, good compatibility and the like, and has good insulativity after film forming, and the acrylic acid is an important organic synthetic raw material and a synthetic resin monomer, is an ethylene monomer with very high polymerization speed, is easy to self-polymerize or polymerize with other organic matters, and can improve the viscosity of the waterborne polyurethane after being mixed with the waterborne polyurethane, so that a stable composite film can be easily formed after coating. The defoaming agent has a defoaming effect and reduces the possibility of generating bubbles in the composite film; the curing agent can promote the composite film to be rapidly generated and shorten the film forming time. And can improve the heat conduction effect of composite film through the heat conduction filler, wherein, boron nitride has better heat conduction effect, and is insulating moreover, and the filler has the filling effect, and the compatilizer can improve boron nitride and filler and polymer's compatibility, and then can make composite film have better heat conduction effect and insulation.
Further, the aqueous polyurethane mentioned in the present application is a dispersion of polyurethane dissolved in water, wherein the ionic type of the aqueous polyurethane is anionicA seed; the solid content is 45-55%; the viscosity is 200-500 mPa.s; the specific gravity is 1.0-1.1g/cm 3 . The composite film formed by the waterborne polyurethane with the solid content range, the viscosity range and the specific gravity range has good thermal conductivity, insulativity and low dielectric property, and further has good effect of leading to electronic products, and is not easy to leak electricity.
Preferably, the heat-conducting filler is prepared from boron nitride, a filler and a compatilizer in a weight ratio of 8-12:3-5: 1.
The crystal of the boron nitride, which is composed of nitrogen atoms and boron atoms, has good insulation property and thermal conductivity, and can further improve the insulation property and the thermal conductivity of the composite film, but the inertia of the boron nitride is large, and the boron nitride is not easy to disperse in a raw material system of the composite film, so that the compatibility of the boron nitride and a polymer is improved by adding a compatilizer, the boron nitride is uniformly dispersed in the raw material system of the composite film, the electrical conductivity and the insulation property of the composite film are improved, and the filler has a filling effect.
The boron nitride is modified boron nitride, and the modified boron nitride comprises the following preparation steps:
step 1: weighing 0.2-0.3 part of sodium pyrophosphate, 5-8 parts of sodium hydroxide and 1-3 parts of potassium hydroxide according to parts by weight, dissolving in 100 parts of water, heating to 55-75 ℃, adding 20-30 parts of boron nitride while stirring, stirring for 3-5h, filtering and drying to obtain pretreated boron nitride;
step 2: weighing 0.3-0.8 part of fatty alcohol-polyoxyethylene ether, 30-50 parts of 55-75% alcohol solution and 5-10 parts of 4-methyl-2-pentanol by weight, adding all the pretreated boron nitride obtained in the step 1, vibrating for 2-3h, filtering and drying to obtain the modified boron nitride.
The method comprises the steps of dissolving sodium hydroxide and potassium hydroxide in water to obtain a strong alkali solution, wherein the strong alkali solution has strong alkalinity, further activating boron nitride, etching the surface of the boron nitride, adding sodium pyrophosphate as dispersibility to improve the dispersibility of the boron nitride, fully contacting the boron nitride with the alkali solution, fully activating the boron nitride by stirring, and enabling the obtained pretreated boron nitride to be easily subjected to hydroxylation reaction.
In the step 2, the fatty alcohol-polyoxyethylene ether is used as a surfactant, so that the diffusivity and the dispersibility are good, the dispersion of the pretreated boron nitride can be promoted, and the pretreated boron nitride can be hydroxylated conveniently; meanwhile, the alcohol solution and the 4-methyl-2-pentanol are used as hydroxyl sources of the pretreated boron nitride and can be matched with fatty alcohol-polyoxyethylene ether to promote the hydroxylation of the pretreated boron nitride, so that the obtained modified boron nitride has better hydrophilicity, the inertia of the boron nitride is reduced, the compatibility of the modified boron nitride and a compatilizer is improved, the dispersibility of the boron nitride in a composite film raw material system is improved, the composite film obtains better heat conductivity and insulativity, and the composite film has better heat dissipation when being used for electronic products, and meanwhile, the possibility of electric leakage of the electronic products is reduced.
Preferably, the filler is prepared from mica powder, glass micro powder and aluminum nitride in a weight ratio of 4-6:1-3: 1.
The mica powder has insulativity and strong adhesive force, so that the mica powder is easy to compound with a polymer, and has the performance of resisting ultraviolet rays, infrared rays and the like; the glass beads have the advantages of light weight, low heat conduction, insulation and the like; and aluminium nitride has higher heat transfer capacity, and has insulating nature, and then carry out the complex through mica powder, glass miropowder, aluminium nitride and can improve the insulating nature of heat conduction filler, the heat conduction effect, and then improve the heat conduction effect of the composite film who makes, when making this composite film be used for the electronic product heat dissipation, can improve the radiating effect, this composite film has lower dielectric simultaneously, ultraviolet resistance and anti-infrared effect, reduce the possibility that the ion sees through composite film when being used for the electronic product, reduce the possibility that the electric shock appears, the people who reduces to use the electronic product simultaneously receives the influence of ultraviolet.
Preferably, the compatilizer is composed of titanate coupling agent, aluminate coupling agent and organosilicon.
After the titanate coupling agent, the aluminate coupling agent and the organic silicon are compounded, the boron nitride and the filler are combined, so that the obtained heat-conducting filler has good compatibility with a polymer, the heat-conducting filler is fully uniformly mixed with a raw material system of the composite film, the heat-conducting effect and the insulating property of the composite film are improved, the heat-radiating effect of the composite film for an electronic product is further improved, and meanwhile, the composite film has lower dielectric property and reduces the possibility of electric shock. Meanwhile, the organic silicon has better high temperature resistance and insulativity, and the insulativity and the high temperature resistance of the composite film are further improved.
Preferably, the ratio of the titanate coupling agent to the aluminate coupling agent to the organosilicon is 3-5:2-3: 1.
The organic silicon is preferably vinyl trimethoxy silane which is a silane coupling agent and can act synergistically with a titanate coupling agent and an aluminate coupling agent to further promote lipophilicity of boron nitride and a filler, so that the boron nitride and the filler have better dispersibility in a raw material system of the composite film, the heat conduction effect and the insulativity of the composite film are improved, and the composite film has lower dielectric property, so that when the composite film is used for an electronic product, the composite film has better heat dissipation effect and lower dielectric property, and the possibility of electric leakage is reduced.
Preferably, the heat conductive filler comprises the following preparation steps:
step 1: dissolving titanate coupling agent, aluminate coupling agent and organic silicon in water at a weight ratio of 3-5:2-3:1, and shaking for 15-20min to obtain compatible liquid;
step 2: weighing 8-15 parts of boron nitride and 3-5 parts of filler according to parts by weight, and uniformly mixing to obtain a mixture; and spraying the compatible liquid on the mixture until the mixture is completely wetted, uniformly stirring, grinding for 1-3h, drying, and sieving by a sieve of 100 meshes and 200 meshes to obtain the heat-conducting filler.
The heat-conducting filler prepared by the process is more easily compatible with the polymer, so that the heat conductivity coefficient of the heat-radiating film is improved. And the compatible liquid is fully combined with the heat-conducting filler in a grinding mode.
Preferably, the curing agent is p-hydroxybenzene sulfonic acid.
The p-hydroxybenzene sulfonic acid has good curing effect, shortens the time for forming the composite film and improves the production efficiency.
Preferably, the defoaming agent is one or more of polyoxypropylene glycerol ether, higher alcohol fatty acid ester compound and polyoxypropylene polyoxyethylene glycerol ether.
One or two of polyoxypropylene glycerol ether, a high-alcohol fatty acid ester compound and polyoxypropylene polyoxyethylene glycerol ether are adopted as a defoaming agent, so that a good defoaming effect is achieved, and bubbles generated by a composite film are reduced.
Preferably, the dispersing agent is polyvinylpyrrolidone and/or fatty alcohol-polyoxyethylene ether.
The polyvinylpyrrolidone and/or the fatty alcohol-polyoxyethylene ether are/is selected as the dispersing agent, so that the dispersion of the raw material system of the composite film can be promoted, the raw materials of the composite film are mixed more uniformly, and the performance of the composite film is improved.
In a second aspect, a method for preparing a composite film with low dielectric constant and high thermal conductivity comprises the following steps: weighing acrylic acid, waterborne polyurethane, a dispersing agent and water, stirring for 10-20min, adding sodium bicarbonate to adjust the pH value to 7-8, stirring for 20-30min, adding heat-conducting fillers in 2-3 batches, stirring uniformly, adding a defoaming agent and a curing agent, stirring uniformly to obtain a compound emulsion, coating the compound emulsion on the surface of a base material, drying and curing to form a film on the surface of the base material, separating the film from the base material to obtain a composite film, wherein the thickness of the composite film is 0.05-1 mm.
The preparation method has the advantages of high production efficiency and yarn, the obtained composite film has good thermal conductivity and low dielectric, wherein sodium bicarbonate is used as a pH regulator, a small amount of sodium bicarbonate is slowly added while stirring when the pH value is regulated, then the test is carried out, and the addition can be stopped when the pH value obtained by the test is 7 or 8.
In summary, the present application has the following beneficial effects:
1. through adopting aqueous polyurethane and acrylic acid to compound, the composite film who makes has better insulating nature and low dielectric, further adds heat conduction filler, improves composite film's heat conduction effect, and then makes composite film have heat conduction effect, insulating nature simultaneously, and obtains lower dielectric, and then when this composite film is used for electronic product, has better radiating effect, and is difficult for producing the possibility of electrocuteeing.
2. According to the preparation method of the modified boron nitride, the surface of the boron nitride is activated through a strong alkaline solution, the dispersibility of the boron nitride is improved by adding sodium pyrophosphate as a surfactant, the boron nitride is fully contacted with the alkaline solution, and the boron nitride is fully activated through stirring to obtain the pretreated boron nitride; and then, the fatty alcohol-polyoxyethylene ether is utilized to improve the dispersibility of the pretreated boron nitride in the alcohol solution, so that the pretreated boron nitride is fully hydroxylated, the hydrophilicity of the modified boron nitride is improved, the inertia of the boron nitride is reduced, the compatibility of the modified boron nitride and a compatilizer is improved, the dispersibility of the boron nitride in a composite film raw material system is improved, the composite film obtains better heat conductivity and insulativity, and further the composite film can have better heat dissipation when being used for an electronic product, and meanwhile, the possibility of electric leakage of the electronic product is reduced.
3. According to the preparation method of the heat-conducting filler, the compatible liquid is fully combined with the heat-conducting filler in a grinding mode, the lipophilicity of boron nitride is improved, the dispersibility of the boron nitride in a composite film raw material system is further improved, the composite film obtains better heat conductivity and insulativity, and the composite film can have better heat dissipation when being used for electronic products, and meanwhile, the possibility of electric leakage of the electronic products is reduced.
Detailed Description
The present application is described in further detail below with reference to preparation examples and examples.
Polyvinylpyrrolidone, total nitrogen amount (N): 11.5-12.8%, relative molecular mass: 10000-;
fatty alcohol polyoxyethylene ether, average molecular weight: 575-605.
Preparation example of modified boron nitride
Preparation example 1
A modified boron nitride comprises the following preparation steps:
step 1: weighing 0.2Kg of sodium pyrophosphate, 5Kg of sodium hydroxide and 1Kg of potassium hydroxide, dissolving in 100Kg of water, heating to 55 ℃, adding 20Kg of boron nitride while stirring, stirring for 3h, filtering with a suction pump, and drying the filter residue in an oven for 8h to obtain pretreated boron nitride;
step 2: weighing 0.3Kg of fatty alcohol-polyoxyethylene ether, 30Kg of 55% alcohol solution and 5Kg of 4-methyl-2-pentanol, adding all the pretreated boron nitride obtained in the step 1, putting ultrasonic waves to vibrate for 2Kgh, wherein the frequency of the ultrasonic waves is 40KHZ, filtering by using a suction pump, and putting filter residues into an oven to dry for 6 hours to obtain the modified boron nitride.
Preparation example 2
A modified boron nitride comprises the following preparation steps:
step 1: weighing 0.3Kg of sodium pyrophosphate, 6Kg of sodium hydroxide and 2Kg of potassium hydroxide, dissolving in 100Kg of water, heating to 65 ℃, adding 25Kg of boron nitride while stirring, stirring for 4h, filtering with a suction pump, and drying the filter residue in an oven for 8h to obtain pretreated boron nitride;
step 2: weighing 0.5Kg of fatty alcohol-polyoxyethylene ether, 40Kg of 65% alcohol solution and 7Kg of 4-methyl-2-pentanol, adding all the pretreated boron nitride obtained in the step 1, putting the pretreated boron nitride into ultrasonic waves for vibration for 2.5h, wherein the frequency of the ultrasonic waves is 40KHZ, filtering the mixture by using a suction pump, and putting filter residues into an oven for drying for 6h to obtain the modified boron nitride.
Preparation example 3
A modified boron nitride comprises the following preparation steps:
step 1: weighing 0.3Kg of sodium pyrophosphate, 8Kg of sodium hydroxide and 3Kg of potassium hydroxide, dissolving in 100Kg of water, heating to 75 ℃, adding 30Kg of boron nitride while stirring, stirring for 5h, filtering with a suction pump, and drying the filter residue in an oven for 6h to obtain pretreated boron nitride;
step 2: weighing 0.8Kg of fatty alcohol-polyoxyethylene ether, 50Kg of 75% alcohol solution by mass and 10Kg of 4-methyl-2-pentanol, adding all the pretreated boron nitride obtained in the step 1, putting the pretreated boron nitride into ultrasonic waves for vibration for 3 hours, filtering the pretreated boron nitride by using a suction pump, and putting filter residues into an oven for drying for 6 hours to obtain the modified boron nitride.
Comparative example for preparation of modified boron nitride
Preparation of comparative example 1
Comparative example 1 was prepared to differ from example 2 in that: sodium pyrophosphate was replaced with sodium hydroxide in equal amounts.
Preparation of comparative example 2
A modified boron nitride comprises the following preparation steps:
weighing 1.5Kg of fatty alcohol-polyoxyethylene ether, 40Kg of 65% alcohol solution and 7Kg of 4-methyl-2-pentanol, adding all the pretreated boron nitride obtained in the step 1, putting the pretreated boron nitride into ultrasonic waves for vibration for 6.5h, filtering the pretreated boron nitride by using a suction pump, and putting filter residues into an oven for drying for 14h to obtain the modified boron nitride.
Preparation example of Heat conductive Filler
Preparation example 4
The preparation of the heat-conducting filler comprises the following steps:
step 1: weighing 0.5Kg of titanate coupling agent, 0.33Kg of aluminate coupling agent and 0.17Kg of organic silicon, dissolving in water, and placing in ultrasonic waves for shaking for 15min, wherein the frequency of the ultrasonic waves is 33KHZ, so as to obtain compatible liquid;
step 2: weighing 8Kg of modified boron nitride obtained in preparation example 3, 2Kg of mica powder, 0.5Kg of glass beads and 0.5Kg of aluminum nitride, and uniformly mixing to obtain a mixture; and spraying the compatible liquid on the mixture until the mixture is completely wetted, uniformly stirring, grinding in a grinding machine for 1h, drying in a drying oven for 10h, and sieving by a 100-mesh sieve to obtain the heat-conducting filler.
Preparation example 5
The preparation of the heat-conducting filler comprises the following steps:
step 1: weighing 0.53Kg of titanate coupling agent, 0.33Kg of aluminate coupling agent and 0.14Kg of organic silicon, dissolving in water, and placing in ultrasonic waves for vibration for 18min, wherein the frequency of the ultrasonic waves is 33KHZ, so as to obtain compatible liquid;
step 2: weighing 10Kg of modified boron nitride obtained in preparation example 2, 2.5Kg of mica powder, 1Kg of glass beads and 0.5Kg of aluminum nitride, and uniformly mixing to obtain a mixture; and spraying the compatible liquid on the mixture until the mixture is completely wetted, uniformly stirring, grinding for 2h in a grinding machine, drying for 10h in an oven, and sieving by a 150-mesh sieve to obtain the heat-conducting filler.
Preparation example 6
The preparation of the heat-conducting filler comprises the following steps:
step 1: weighing 0.56Kg of titanate coupling agent, 0.33Kg of aluminate coupling agent and 0.11Kg of organic silicon, dissolving in water, and placing in ultrasonic waves for vibration for 20min, wherein the frequency of the ultrasonic waves is 33KHZ, so as to obtain compatible liquid;
step 2: weighing 12Kg of modified boron nitride obtained in preparation example 3, 3Kg of mica powder, 1.5Kg of glass beads and 0.5Kg of aluminum nitride, and uniformly mixing to obtain a mixture; and spraying the compatible liquid on the mixture until the mixture is completely wetted, uniformly stirring, grinding for 3h in a grinding machine, drying for 10h in an oven, and sieving by a 200-mesh sieve to obtain the heat-conducting filler.
Preparation example 7
Preparation 7 differs from preparation 5 in that: the modified boron nitride obtained in preparation comparative example 1 was used.
Preparation example 8
Preparation 8 differs from preparation 5 in that: the modified boron nitride obtained in preparation comparative example 2 was used. Preparation 9 differs from preparation 5 in that: commercially available boron nitride is used.
Comparative preparation example of Heat-conducting Filler
Preparation of comparative example 3
Preparative comparative example 3 differs from preparative example 5 in that: the titanate coupling agent is replaced by the aluminate coupling agent in equal amount.
Preparation of comparative example 4
Comparative preparation example 4 differs from preparation example 5 in that: the titanate coupling agent and the aluminate coupling agent are replaced by organic silicon in equal amount.
Preparation of comparative example 5
Comparative preparation example 5 differs from preparation example 5 in that: the mica powder, the glass beads and the aluminum nitride are replaced by boron nitride.
Preparation of comparative example 6
The preparation of the heat-conducting filler comprises the following steps:
weighing 12Kg of modified boron nitride obtained in preparation example 3, 3Kg of mica powder, 1.5Kg of glass beads, 0.56Kg of titanate coupling agent, 0.33Kg of aluminate coupling agent, 0.11Kg of organic silicon and 0.5Kg of aluminum nitride, stirring and mixing for 18min, putting into a grinder for grinding for 3h, putting into an oven for drying for 10h, and sieving with a 200-mesh sieve to obtain the heat-conducting filler.
Examples
Example 1
The preparation method of the composite film with low dielectric constant and high thermal conductivity comprises the following steps:
weighing 50Kg of waterborne polyurethane, 0.3Kg of sodium pyrophosphate, 5Kg of acrylic acid and 20Kg of deionized water, stirring for 10min, adding sodium bicarbonate to adjust the pH value to 7, stirring for 20min, adding 12Kg of the heat-conducting filler obtained in preparation example 5 in 2 batches, stirring uniformly, adding 0.2Kg of polyoxypropylene glycerol ether and 0.05Kg of p-hydroxybenzene sulfonic acid, stirring uniformly to obtain a compound emulsion, coating the compound emulsion on the surface of a substrate, putting the compound emulsion into a 55 ℃ oven for drying until the compound emulsion is completely cured, forming a film on the surface of the substrate, and separating the film from the substrate to obtain the composite film, wherein the thickness of the composite film is 0.05 mm.
Example 2
The preparation method of the composite film with low dielectric constant and high thermal conductivity comprises the following steps:
weighing 60Kg of waterborne polyurethane, 0.1Kg of sodium pyrophosphate, 0.3Kg of polyvinylpyrrolidone, 6Kg of acrylic acid and 25K of deionized water, stirring for 15min, adding sodium bicarbonate to adjust the pH value to 8, stirring for 25min, adding 15Kg of the heat-conducting filler obtained in preparation example 5 in 3 batches, stirring uniformly, adding 0.2Kg of polyoxypropylene glycerol ether, 0.1Kg of polyoxypropylene polyoxyethylene glycerol ether and 0.08Kg of p-hydroxybenzene sulfonic acid, stirring uniformly to obtain a compound emulsion, coating the compound emulsion on the surface of a substrate, drying in an oven at 55 ℃ until the compound emulsion is completely cured, forming a film on the surface of the substrate, and separating the film from the substrate to obtain the compound film, wherein the thickness of the compound film is 0.2 mm.
Example 3
The preparation method of the composite film with low dielectric constant and high thermal conductivity comprises the following steps:
weighing 70Kg of waterborne polyurethane, 0.1Kg of sodium pyrophosphate, 0.3Kg of polyvinylpyrrolidone, 0.1Kg of fatty alcohol-polyoxyethylene ether, 8Kg of acrylic acid and 25Kg of deionized water, stirring for 20min, adding sodium bicarbonate to adjust the pH value to 7, stirring for 30min, adding 18Kg of the heat-conducting filler obtained in preparation example 5 in 3 batches, stirring uniformly, adding 0.2Kg of polyoxypropylene glycerol ether, 0.1Kg of polyoxypropylene polyoxyethylene glycerol ether and 0.1Kg of p-hydroxybenzene sulfonic acid, stirring uniformly to obtain a compound emulsion, coating the compound emulsion on the surface of a substrate, drying in an oven at 55 ℃ until the compound emulsion is completely cured, forming a film on the surface of the substrate, separating the film from the substrate to obtain the compound film, wherein the thickness of the compound film is 1 mm.
Examples 4 to 12
Examples 4-12 differ from example 2 in that: the sources of the heat-conducting fillers are different, and are specifically shown in table 1;
table 1 sources of thermally conductive fillers for examples 4-12
Examples Sources of modified fillers
Example 4 Preparation example 4
Example 5 Preparation example 6
Example 6 Preparation example 7
Example 7 Preparation example 8
Example 8 Preparation example 9
Example 9 Preparation of comparative example 3
Example 10 Preparation of comparative example 4
Example 11 Preparation of comparative example 5
Example 12 Preparation of comparative example 6
Comparative example
Comparative example 1
Comparative example 1 differs from example 2 in that: replacement of thermally conductive fillers into waterborne polyurethanes
Comparative example 2
Comparative example 2 differs from example 2 in that: the heat conductive filler is replaced with carbon nanotubes.
Performance test
The compound emulsions obtained in examples 1 to 12 and comparative examples 1 to 2 were coated, dried and cured to form a composite film with a thickness of 0.5mm (the curing and curing process is the same as the drying and curing process in the preparation method of the present application, but a film with a thickness of 0.5mm is uniformly prepared, which is convenient for the following performance tests), and the compound emulsions were used for testing the thermal conductivity and the dielectric constant by the following testing methods, and the specific data are shown in table 2.
Detection method/test method
1. Coefficient of thermal conductivity
Coefficient of thermal conductivity: the test of the thermal conductivity coefficient is carried out at 25 ℃ by using a NETZSCH HY 009 thermal conductivity tester according to the test of the national standard GB/T2588-2008.
2. Dielectric constant of
Dielectric constant: the dielectric constant is detected by referring to GB/T31838.1-2015, and a dielectric constant tester is adopted, and the model is as follows: ZJD-B; test frequency range: 10 kHz-70 MHz.
TABLE 2 Experimental data for examples 1-12 and comparative examples 1-2
Figure BDA0003638066240000091
Figure BDA0003638066240000101
Combining example 2 and comparative example 1 and table 2, it can be seen that the thermal conductivity of example 2 is 12.4(W/m.k) higher than that of comparative example 1, and the dielectric constant of example 2 is 2.7 lower than that of comparative example 1, indicating that the thermal conductive filler has better thermal conductive effect and low dielectric constant.
Combining example 2 and comparative example 1 and table 2, it can be seen that the dielectric constant of example 2 is lower than that of comparative example 2 by 3.5, which indicates that the composite film obtained after carbon nanotubes are used as the heat conductive filler has higher dielectric.
By combining example 2 and examples 6-7 and table 2, it can be seen that the dielectric constant of example 2 is lower than that of example 7, and the thermal conductivity is higher than that of examples 6-7, which further illustrates that the addition of sodium pyrophosphate can improve the dispersibility of boron nitride, so that boron nitride can be better activated, and further boron nitride can be easier to hydroxylate, so that the modified boron nitride has better hydrophilicity, and is easy to combine with compatibility.
Combining example 2 and example 9 with table 2, it can be seen that example 2 has a higher thermal conductivity than example 9, and further that the modified boron nitride is easier to bond with a compatibilizer, and further easier to bond with a polymer, and improves the dispersibility of the boron nitride in the raw material system of the composite film.
By combining the examples 2 and 9-11 and combining the table 2, it can be seen that the dielectric constant of the example 2 is lower than that of the examples 9-11, and the thermal conductivity is higher than that of the examples 9-11, which shows that the composite film prepared by compounding the titanate coupling agent, the aluminate coupling agent and the organosilicon has better modification effect, and further can improve the dispersibility of the filler and the modified boron nitride in the polymer, and further improve the thermal conductivity of the composite film, and has the advantage of low dielectric.
By combining example 2 and example 12 and table 2, it can be seen that the dielectric constant of example 2 is lower than that of example 12, and the thermal conductivity is higher than that of example 12, which indicates that the raw material system of the thermal conductive filler and the composite film obtained by the preparation method of the present application has better dispersibility, so that the composite film has better thermal conductivity and low dielectric constant.
The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims (10)

1. A composite film with low dielectric and high thermal conductivity is characterized in that: the feed is prepared from the following raw materials in parts by weight:
aqueous polyurethane: 50-70 parts of
Acrylic acid: 5-8 parts of
Heat-conducting filler: 12 to 18 portions of
Dispersing agent: 0.3 to 0.5 portion
Defoaming agent: 0.2 to 0.3 portion
Curing agent: 0.05 to 0.1 portion.
2. The composite film with low dielectric constant and high thermal conductivity as claimed in claim 1, wherein: the heat-conducting filler is prepared from boron nitride, a filler and a compatilizer according to the weight ratio of 8-12:3-5: 1.
3. The composite film with low dielectric constant and high thermal conductivity as claimed in claim 2, wherein: the boron nitride is modified boron nitride, and the modified boron nitride comprises the following preparation steps:
step 1: weighing 0.2-0.3 part of sodium pyrophosphate, 5-8 parts of sodium hydroxide and 1-3 parts of potassium hydroxide according to parts by weight, dissolving in 100 parts of water, heating to 55-75 ℃, adding 20-30 parts of boron nitride while stirring, stirring for 3-5h, filtering and drying to obtain pretreated boron nitride;
and 2, step: weighing 0.3-0.8 part by weight of fatty alcohol-polyoxyethylene ether, 30-50 parts by weight of 55-75% alcohol solution and 5-10 parts by weight of 4-methyl-2-pentanol, adding all the pretreated boron nitride obtained in the step 1, vibrating for 2-3h, filtering and drying to obtain the modified boron nitride.
4. The composite film with low dielectric constant and high thermal conductivity as claimed in claim 2, wherein: the filler is prepared from mica powder, glass micropowder and aluminum nitride in a weight ratio of 4-6:1-3: 1.
5. The composite film with low dielectric constant and high thermal conductivity as claimed in claim 2, wherein: the compatilizer is prepared by mixing titanate coupling agent, aluminate coupling agent and organic silicon in a weight ratio of 3-5:2-3: 1.
6. The composite film with low dielectric constant and high thermal conductivity as claimed in any one of claims 2 to 5, wherein: the heat-conducting filler comprises the following preparation steps:
step 1: dissolving titanate coupling agent, aluminate coupling agent and organic silicon in water at a weight ratio of 3-5:2-3:1, and shaking for 15-20min to obtain compatible liquid;
step 2: weighing 8-15 parts of boron nitride and 3-5 parts of filler according to parts by weight, and uniformly mixing to obtain a mixture; and spraying the compatible liquid on the mixture until the mixture is completely wetted, uniformly stirring, grinding for 1-3h, drying, and sieving by a sieve of 100 meshes and 200 meshes to obtain the heat-conducting filler.
7. The composite film with low dielectric constant and high thermal conductivity as claimed in claim 1, wherein: the curing agent is p-hydroxybenzene sulfonic acid.
8. The composite film with low dielectric constant and high thermal conductivity as claimed in claim 1, wherein: the defoaming agent is one or more of polyoxypropylene glycerol ether, a higher alcohol fatty acid ester compound and polyoxypropylene polyoxyethylene glycerol ether.
9. The composite film with low dielectric constant and high thermal conductivity as claimed in claim 1, wherein: the dispersing agent is polyvinylpyrrolidone and/or fatty alcohol-polyoxyethylene ether.
10. A method for preparing a low dielectric high thermal conductive composite film according to any one of claims 1 to 9, wherein: weighing acrylic acid, waterborne polyurethane, a dispersing agent and water, stirring for 10-20min, adding sodium bicarbonate to adjust the pH value to 7-8, stirring for 20-30min, adding heat-conducting fillers in 2-3 batches, stirring uniformly, adding a defoaming agent and a curing agent, stirring uniformly to obtain a compound emulsion, coating the compound emulsion on the surface of a base material, drying and curing to form a film on the surface of the base material, separating the film from the base material to obtain a composite film, wherein the thickness of the composite film is 0.05-1 mm.
CN202210507740.9A 2022-05-11 2022-05-11 Low-dielectric high-thermal-conductivity composite film and preparation method thereof Pending CN114835861A (en)

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CN106085190A (en) * 2016-07-30 2016-11-09 许星星 A kind of modified aqueous polyurethane heat-conductive coating for power distribution cabinet and preparation method thereof
CN109181511A (en) * 2018-07-19 2019-01-11 浙江博菲电气股份有限公司 A kind of high heat conductive insulating water paint
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JP2015122360A (en) * 2013-12-20 2015-07-02 日東電工株式会社 Heat diffusing film and electronic device
CN106085190A (en) * 2016-07-30 2016-11-09 许星星 A kind of modified aqueous polyurethane heat-conductive coating for power distribution cabinet and preparation method thereof
CN109181511A (en) * 2018-07-19 2019-01-11 浙江博菲电气股份有限公司 A kind of high heat conductive insulating water paint
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* Cited by examiner, † Cited by third party
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