CN117423492A - High-temperature-resistant flexible composite conductive film - Google Patents
High-temperature-resistant flexible composite conductive film Download PDFInfo
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- CN117423492A CN117423492A CN202311410693.7A CN202311410693A CN117423492A CN 117423492 A CN117423492 A CN 117423492A CN 202311410693 A CN202311410693 A CN 202311410693A CN 117423492 A CN117423492 A CN 117423492A
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B5/00—Non-insulated conductors or conductive bodies characterised by their form
- H01B5/14—Non-insulated conductors or conductive bodies characterised by their form comprising conductive layers or films on insulating-supports
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/20—Conductive material dispersed in non-conductive organic material
- H01B1/24—Conductive material dispersed in non-conductive organic material the conductive material comprising carbon-silicon compounds, carbon or silicon
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
- H01B13/0026—Apparatus for manufacturing conducting or semi-conducting layers, e.g. deposition of metal
Abstract
The invention belongs to the technical field of conductive films, and in particular relates to a high-temperature-resistant flexible composite conductive film which comprises a high-temperature-resistant conductive substrate layer and a conductive carbon layer coated on the surface of the high-temperature-resistant conductive substrate layer; the surface of the high-temperature-resistant conductive substrate layer is distributed with a plurality of microporous structures, and the surface of the high-temperature-resistant conductive substrate layer is distributed with a plurality of polystyrene microspheres. The conductive carbon layer is prepared from conductive slurry; the conductive paste comprises the following components in parts by weight: 10-20 parts of carboxyl carbon nano tube, 20-30 parts of graphite powder, 5-10 parts of conductive carbon black, 3-6 parts of dispersing agent, 2-10 parts of adhesive, 0.5-2 parts of polycarbodiimide and 300-500 parts of solvent; the adhesive is at least one of carboxymethyl cellulose and carboxymethyl starch. According to the flexible composite conductive film, the film forming resin does not need to be added in the conductive carbon layer, an adhesive layer does not need to be arranged between the conductive carbon layer and the substrate layer, so that good adhesive force between the conductive carbon layer and the substrate layer can be realized, and the conductivity of the flexible composite conductive film is improved.
Description
Technical Field
The invention belongs to the technical field of conductive films, and particularly relates to a high-temperature-resistant flexible composite conductive film.
Background
As an electronic functional material, the conductive paste is widely used in the main fields of batteries, ink, capacitors, electric heating and the like, and in recent years, graphene and carbon nanotubes are widely used for preparing carbon-based conductive paste because of their excellent conductivity as conductive fillers. The prepared conductive paste is directly coated on the surfaces of plastic films such as PET substrate films, PE substrate films, PI substrate films and the like in a silk screen printing or blade coating or spraying mode, and then baked and cured to obtain the flexible conductive carbon film. However, there are few patents reporting improvement of performance of the substrate, and in order to achieve adhesion between the conductive paste and the substrate, one or more of polyurethane resin, acrylic resin, epoxy resin and the like are basically used as a system film forming substance in the formulation of the conductive paste reported at present, and the conductive paste is prepared by coating the substrate and curing the coated substrate. The conductive paste has the advantages that the conductive performance is general due to the fact that a large amount of resin is added into the conductive paste, the carbon content is small, and meanwhile, the temperature resistance of the prepared conductive carbon film is low due to the fact that the temperature resistance of film forming substances is low, and the conductive carbon film cannot be used in a scene that the temperature is higher than 200 ℃ or even higher. Meanwhile, it is reported that no matter the conductive film of graphene or other carbon system is currently used, because the adhesion between the conductive carbon film and the substrate is poor, an adhesive layer is usually arranged to realize the combination between the conductive layer and the substrate, and the conductive or heat conducting effect of the prepared conductive film is greatly reduced.
Disclosure of Invention
The invention aims to provide a high-temperature-resistant flexible composite conductive film, and aims to solve the technical problems that an adhesive force between a conductive carbon layer and a substrate layer of the conventional flexible composite conductive film is poor, a large amount of film-forming resin needs to be added into the conductive carbon layer, and an adhesive layer needs to be arranged between the conductive carbon layer and the substrate layer.
In order to achieve the above object, the present invention adopts the following technical scheme:
the invention provides a high-temperature-resistant flexible composite conductive film, which comprises a high-temperature-resistant conductive substrate layer and a conductive carbon layer coated on the surface of the high-temperature-resistant conductive substrate layer; the surface of the high-temperature-resistant conductive substrate layer is distributed with a plurality of microporous structures, and the surface of the high-temperature-resistant conductive substrate layer is provided with a plurality of polystyrene microspheres.
According to the invention, the micropore structure and the polystyrene microspheres are arranged on the surface of the high-temperature-resistant conductive substrate layer, so that after the conductive paste is coated on the surface of the high-temperature-resistant conductive substrate layer, part of the conductive paste can enter the micropore structure, and the other part of the conductive paste can be combined with the polystyrene microspheres, so that the conductive carbon layer formed after the conductive paste is solidified can be firmly combined with the high-temperature-resistant conductive substrate layer, an adhesive layer and a large amount of film forming resin are not required to be additionally adopted for adhering the conductive carbon layer and the conductive substrate layer, the conductive carbon layer and the conductive substrate layer are not easy to separate, and the prepared composite conductive film has good conductive performance and high-temperature resistance.
The upper surface and the lower surface of the high-temperature-resistant conductive substrate layer are respectively provided with a conductive carbon layer, the thickness of the high-temperature-resistant conductive substrate layer is 8-25 mu m, the thickness of the conductive carbon layer is 5-25 mu m, and preferably, the thickness of the conductive carbon layer is 7-15 mu m.
Wherein the conductive carbon layer is prepared from conductive slurry; the conductive paste comprises the following components in parts by weight:
the adhesive is at least one of carboxymethyl cellulose and carboxymethyl starch.
The conductive paste is compounded by adopting the components, the weight ratio of the components is strictly controlled, the prepared conductive paste has good film forming property and cohesiveness under the condition of no film forming resin, the conductive carbon layer prepared by adopting the conductive paste has good bonding effect with a substrate layer, the prepared conductive carbon layer has high conductivity, high wear resistance, water resistance and high temperature resistance, and good adhesive force, and no adhesive layer is required to be additionally arranged between the conductive carbon layer and the substrate layer. Specifically, the conductive paste disclosed by the invention can be used for improving the viscosity of the paste and improving the adhesive force between the conductive carbon layer and the substrate layer by selecting a specific type of adhesive, and can be used for carrying out a synergistic effect with a dispersing agent to disperse the carbon nano-tubes, the graphite powder and the conductive carbon black and improving the dispersing effect among all components in the paste.
Wherein the dispersing agent is at least one of polyvinyl alcohol, polyvinylpyrrolidone, vinylpyrrolidone and vinyl acetate copolymer. The dispersing agent of the type has good dispersing effect, can improve the dispersing uniformity of each component in the conductive paste, further improve the conductive performance of the conductive paste, and lead the finally prepared conductive film to have good conductivity, wear resistance, water resistance and mechanical property.
Wherein the solvent is deionized water or N-methyl pyrrolidone.
The preparation method of the conductive paste comprises the following steps:
s1, uniformly mixing graphite powder, an adhesive and a part of solvent, and grinding for 0.5-6 hours at the speed of 1000-6000rpm/min by using grinding equipment to obtain C1 slurry;
s2, adding a carboxyl carbon nano tube, a dispersing agent and the rest solvent into the C1 slurry, and homogenizing for 6-12 times by using a high-pressure homogenizer at a pressure of 600-1000bar to obtain C2 slurry;
s3, adding conductive carbon black into the C2 slurry, and homogenizing for 3-6 times by using a high-pressure homogenizer under the pressure of 600-1000bar to obtain C3 slurry;
s4, adding polycarbodiimide into the C3 slurry, and dispersing for 0.5-1h at a speed of 1000-1600rpm/min by adopting a high-speed dispersing machine, wherein the dispersing temperature is less than 15 ℃, so as to obtain the conductive slurry.
The conductive paste is prepared by adopting a graded dispersion and compounding process, so that the dispersion effect of each component in the paste can be improved to the greatest extent, the conductivity and film forming property of the paste are further improved, and the conductive carbon layer prepared by adopting the paste has good film forming effect and adhesive force and high conductivity, wear resistance and water resistance. According to the invention, specific types of adhesives are selected and the grinding speed is controlled, the flake graphite powder is firstly stripped in situ to obtain graphene micro-flakes, then a polymer dispersing agent with viscosity reduction effect is adopted to perform synergistic effect with a thickening binder, and homogenizing pressure is controlled to sequentially disperse the carbon nano tubes and the conductive carbon black, so that the high-solid low-viscosity of the carbon system material is realized, smooth pulping of the slurry is ensured, meanwhile, point, surface and line lap joint is realized through compounding cooperation of the flake graphene, the tubular carbon nano tubes and the nano conductive carbon black, a good conductive path is obtained, and the obtained conductive slurry has high-carbon content high-conductivity characteristic.
And step S4, dispersing by a high-speed dispersing machine, and filtering the slurry through 150-mesh gauze to finally obtain the conductive slurry.
Wherein the carboxyl carbon nano tube is at least one of a multi-wall carbon nano tube and a single-wall carbon nano tube, the diameter of the carboxyl carbon nano tube is 6-50nm, and the tube length is 5-20 mu m.
Wherein the graphite powder is flake graphite powder, and the particle size of the graphite powder is 50-250 mu m.
The preparation method of the conductive carbon layer comprises the following steps: coating the conductive slurry on a high-temperature-resistant conductive substrate layer, curing for 0.2-0.5h at 80-120 ℃, coating a conductive carbon layer on the other surface of the high-temperature-resistant conductive substrate layer according to the method, and curing.
The preparation method of the high-temperature-resistant conductive substrate layer comprises the following steps: adding glass microspheres and conductive powder into polyimide varnish solution, mixing uniformly to form conductive polyimide slurry, coating the conductive polyimide slurry on a PET release film to form a substrate layer, spraying polystyrene microspheres on the surface of the substrate layer, and corroding the cured substrate layer by hydrofluoric acid after the substrate layer is cured to obtain the polyimide film layer with a micropore structure.
According to the invention, the high-temperature resistant polyimide varnish, the glass microspheres and the conductive powder are mixed to prepare the conductive polyimide slurry, after the conductive polyimide slurry is cast and cured through a coating process, part of the glass microspheres are positioned on the surface of the substrate layer, and HF is adopted to etch away the glass microspheres positioned on the surface, so that micropores are left on the polyimide film, and the conductive polyimide film with a micropore structure is obtained. And part of the slurry after the conductive slurry is coated on the polyimide film enters the microporous structure, so that good combination of the conductive carbon layer and the high-temperature-resistant conductive substrate layer is realized, and the adhesive force between the conductive carbon layer and the high-temperature-resistant conductive substrate layer is improved. And the glass microspheres positioned in the high-temperature resistant conductive substrate layer can improve the high-temperature resistance and mechanical properties of the substrate layer. The microporous structure is prepared on the substrate layer by adopting a glass microsphere and hydrofluoric acid etching method, the pore diameter of micropores can be controlled by controlling the size of the glass microsphere, so that the conductive paste can enter the microporous structure during coating, and the good combination between the conductive carbon layer and the substrate layer is improved.
According to the invention, before the conductive polyimide slurry is coated and uncured, the polystyrene microspheres are sprayed, so that the polystyrene microspheres are attached to the surface of the cured polyimide film layer, more anchor points can be provided for coating the conductive carbon layer, and the binding force between the high-temperature-resistant conductive substrate layer and the conductive carbon layer is improved.
The preparation method of the high-temperature-resistant conductive substrate layer comprises the steps of coating the conductive polyimide slurry on a PET release film, firstly baking at 80-110 ℃, removing most of solvent to obtain a semi-cured substrate layer, then stripping the PET release film, spraying polystyrene microspheres on the upper surface and the lower surface of the semi-cured substrate layer, then baking at 120-160 ℃, obtaining the cured substrate layer, and corroding the cured substrate layer by adopting hydrofluoric acid to obtain the polyimide film layer with a microporous structure.
When the high-temperature resistant conductive substrate layer is prepared, the semi-cured substrate layer is obtained by baking at the temperature of 80-110 ℃, then the polystyrene microspheres are sprayed, the semi-cured substrate layer has moderate hardness, the polystyrene microspheres are not only directly immersed in the conductive polyimide slurry and coated by the slurry after being sprayed, but also part of the microspheres are positioned in the substrate layer after being sprayed and are mutually adhered and fixed with the slurry, and the other part of the microspheres protrude out of the substrate layer, so that the binding force of the polystyrene microspheres and the substrate layer can be effectively improved, the polystyrene microspheres are not easy to separate from the substrate layer, and the binding force of the conductive carbon layer and the substrate layer can be further improved.
The polystyrene microsphere is carboxylated polystyrene microsphere, carboxyl functional groups in the carboxylated polystyrene microsphere can react with polycarbodiimide in the conductive carbon layer to generate a crosslinked network structure, and the binding force between the conductive carbon layer and the substrate layer is further improved.
Wherein the glass microsphere is a hollow glass microsphere prepared from soda lime glass or borosilicate glass. The hollow glass microspheres can reduce the overall weight of the composite conductive carbon film on one hand, and facilitate hydrofluoric acid to quickly corrode the composite conductive carbon film on the other hand, so that the preparation efficiency of the microporous structure of the substrate layer is improved.
Wherein the particle size of the glass microsphere is 5-50 mu m. The particle size of the glass microspheres is controlled so as to control the pore size of micropores, so that the conductive slurry can enter the micropore structure during coating, and good combination between the conductive carbon layer and the substrate layer is improved.
The preparation method of the conductive polyimide slurry comprises the following steps: mixing the nano conductive powder, the glass microspheres and the polyimide varnish according to the solid content ratio of 0.025-1:0.025-0.5:100, and then dispersing for 0.5-3 hours at the dispersion speed of 500-3000rpm/min to obtain the conductive polyimide slurry.
The polyimide varnish has a solid content of 20-35% and a viscosity of 800-2500 cps.
The nanometer conductive powder is one or more of nanometer graphene, carbon nano tube, nanometer carbon black, nanometer carbon fiber, nanometer carbon sphere and ketjen black, and the particle size of the nanometer conductive powder is 25 nm-250 nm.
The invention has the beneficial effects that:
according to the invention, the micropore structure and the polystyrene microspheres are arranged on the surface of the high-temperature-resistant conductive substrate layer, so that after the conductive paste is coated on the surface of the high-temperature-resistant conductive substrate layer, part of the conductive paste can enter the micropore structure, and the other part of the conductive paste can be combined with the polystyrene microspheres, so that the conductive carbon layer formed after the conductive paste is solidified can be firmly combined with the high-temperature-resistant conductive substrate layer, and the conductive carbon layer and the conductive substrate layer are not required to be bonded by adopting an adhesive layer, so that the conductive carbon layer and the conductive substrate layer are not easy to separate.
The conductive paste disclosed by the invention can not only improve the viscosity of the paste and improve the adhesive force between the conductive carbon layer and the substrate layer by selecting a specific type of adhesive, but also can be used for being cooperated with a dispersing agent to disperse the carbon nano-tubes, the graphite powder and the conductive carbon black and improve the dispersing effect among all components in the paste.
Detailed Description
For the purpose of making the objects, technical solutions and technical effects of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described, and the embodiments described below are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art without the benefit of the teachings of this invention, are intended to be within the scope of the invention. The specific conditions are not noted in the examples, and are carried out according to conventional conditions or conditions suggested by the manufacturer; the reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
In the description of the present invention, the term "and/or" describes an association relationship of an association object, which means that three relationships may exist, for example, a and/or B may mean: a alone, a and B together, and B alone. Wherein A, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship.
In the description of the present invention, "at least one" means one or more, and "a plurality" means two or more. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively.
It should be understood that the weights of the relevant components mentioned in the embodiments of the present invention may refer not only to the specific contents of the components, but also to the proportional relationship between the weights of the components, so long as the contents of the relevant components are scaled up or down according to the embodiments of the present invention, which are within the scope of the present disclosure. Specifically, the weight in the embodiment of the invention can be mass units well known in the chemical industry field such as mu g, mg, g, kg.
In addition, the expression of a word in the singular should be understood to include the plural of the word unless the context clearly indicates otherwise. The terms "comprises" or "comprising" are intended to specify the presence of stated features, integers, steps, operations, elements, components, or groups thereof, but are not intended to preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof.
In order that the details of the above-described implementations and operations of the present invention may be clearly understood by those skilled in the art, and that the present invention may be embodied with significant improvements in the embodiments of the present invention, the above-described technical solutions will be exemplified by a plurality of embodiments.
Example 1
A high-temperature-resistant flexible composite conductive film comprises a high-temperature-resistant conductive substrate layer and a conductive carbon layer coated on the surface of the high-temperature-resistant conductive substrate layer; the surface of the high-temperature-resistant conductive substrate layer is distributed with a plurality of microporous structures, and the surface of the high-temperature-resistant conductive substrate layer is provided with a plurality of polystyrene microspheres.
The preparation method of the high-temperature-resistant flexible composite conductive film comprises the following steps:
step one, preparing conductive polyimide slurry: mixing 1 part by weight of nano conductive carbon black with the particle size of 25nm, 0.5 part by weight of sodium-calcium hollow glass microspheres with the particle size of 5 mu m and 400 parts by weight of polyimide varnish, wherein the solid content of the polyimide varnish is 25%, the viscosity is 1200cps, and then dispersing for 1h at the dispersion speed of 1600rpm/min to obtain conductive polyimide slurry;
step two, preparing a high-temperature-resistant conductive substrate layer: coating conductive polyimide slurry on a PET double-sided silicon release film with a release force of 5-10 g at 75 mu m by using a coating machine, baking at 95 ℃ to remove most of solvent to obtain a semi-cured substrate layer, peeling the PET double-sided silicon release film, spraying carboxylated polystyrene microspheres on the upper and lower surfaces of the semi-cured substrate layer, baking at 160 ℃ at high temperature to imidize the substrate layer to obtain a substrate layer with a dry film thickness of 12 mu m, etching the cured substrate layer by using hydrofluoric acid to etch hollow glass spheres to leave cavities, repeatedly soaking the etched film for 5 times (replacing water after each soaking), and drying at 100 ℃ to obtain the conductive polyimide substrate layer with a microporous structure;
step three, preparing conductive slurry:
s1, uniformly mixing 30 parts by weight of flake graphite powder with the particle size of 50 mu m, 10 parts by weight of carboxymethyl cellulose adhesive and 300 parts by weight of water, and grinding for 6 hours at the speed of 3000rpm/min by using a vertical sand mill to obtain C1 slurry;
s2, adding 15 parts by weight of carboxyl carbon nano tubes with the tube diameter of 20nm and the tube length of 10 mu m into the C1 slurry, uniformly mixing 6 parts by weight of dispersing agent and 200 parts by weight of water, wherein the dispersing agent is a mixture of vinyl pyrrolidone and vinyl acetate copolymer according to the mass ratio of 1:1, and homogenizing for 6 times by using a high-pressure homogenizer at the pressure of 800bar to obtain C2 slurry;
s3, adding 10 parts by weight of conductive carbon black into the C2 slurry, uniformly mixing, and homogenizing for 3 times by using a high-pressure homogenizer at a pressure of 600bar to obtain C3 slurry;
s4, adding 2 parts by weight of polycarbodiimide into the C3 sizing agent, dispersing for 0.5h at the speed of 1600rpm/min by adopting a high-speed dispersing machine, wherein the dispersing temperature is less than 15 ℃, and filtering the sizing agent through 150-mesh gauze after dispersing to prepare the conductive sizing agent.
Step four, preparing a conductive carbon layer: coating the conductive paste on the first surface of the high-temperature-resistant conductive substrate layer, curing at 110 ℃ for 0.2h to obtain a conductive carbon film semi-finished product with the conductive carbon layer thickness of 15 mu m, coating the conductive carbon paste on the second surface of the high-temperature-resistant conductive substrate layer, curing at 110 ℃ for 0.2h, and coating the conductive carbon film semi-finished product with the conductive carbon layer dry film thickness of 15 mu m to obtain the conductive carbon film semi-finished product with the conductive carbon layer coated on both sides.
Fifth, rolling and manufacturing the high-temperature-resistant flexible conductive carbon film: and rolling the semi-finished conductive carbon film with the conductive carbon layers coated on both sides at normal temperature through a roll squeezer to obtain the high-temperature-resistant flexible composite conductive film.
Example 2
The structure of the high temperature-resistant flexible composite conductive film is the same as that of the high temperature-resistant flexible composite conductive film of example 1.
The preparation method of the high-temperature-resistant flexible composite conductive film comprises the following steps:
step one, preparing conductive polyimide slurry: mixing 0.025 parts by weight of ketjen black with the particle size of 30nm, 0.025 parts by weight of borosilicate hollow glass microspheres with the particle size of 50 mu m and 500 parts by weight of polyimide varnish, wherein the solid content of the polyimide varnish is 20%, the viscosity of the polyimide varnish is 800cps, and then dispersing for 1h at the dispersion speed of 1600rpm/min to obtain conductive polyimide slurry;
step two, preparing a high-temperature-resistant conductive substrate layer: coating conductive polyimide slurry on a PET double-sided silicon release film with a release force of 5-10 g at 50 mu m by using a coating machine, baking at 110 ℃ to remove most of solvent to obtain a semi-cured substrate layer, peeling the PET double-sided silicon release film, spraying carboxylated polystyrene microspheres on the upper and lower surfaces of the semi-cured substrate layer, baking at 160 ℃, imidizing to obtain a substrate layer with a dry film thickness of 25 mu m, etching the cured substrate layer by using hydrofluoric acid to leave cavities after etching the hollow glass spheres, repeatedly soaking the etched substrate layer for 5 times (replacing water after each soaking), and drying at 100 ℃ after soaking to obtain the conductive polyimide substrate layer with a microporous structure;
step three, preparing conductive slurry:
s1, uniformly mixing 30 parts by weight of crystalline flake graphite powder with the particle size of 150 mu m, 10 parts by weight of carboxymethyl cellulose adhesive and 400 parts by weight of water, and grinding for 6 hours at the speed of 3500rpm/min by using a vertical sand mill to obtain C1 slurry;
s2, adding 10 parts by weight of carboxyl carbon nano tubes with the tube diameter of 50nm and the tube length of 15 mu m into the C1 slurry, uniformly mixing the carboxyl carbon nano tubes with 6 parts by weight of polyvinylpyrrolidone and 100 parts by weight of water, and homogenizing the mixture for 6 times by using a high-pressure homogenizer at the pressure of 1000bar to obtain C2 slurry;
s3, adding 10 parts by weight of conductive carbon black into the C2 slurry, uniformly mixing, and homogenizing for 3 times by using a high-pressure homogenizer at a pressure of 600bar to obtain C3 slurry;
s4, adding 2 parts by weight of polycarbodiimide into the C3 sizing agent, dispersing for 0.5h at the speed of 1600rpm/min by adopting a high-speed dispersing machine, wherein the dispersing temperature is less than 15 ℃, and filtering the sizing agent through 150-mesh gauze after dispersing to prepare the conductive sizing agent.
Step four, preparing a conductive carbon layer: and coating the conductive paste on the first surface of the high-temperature-resistant conductive substrate layer, curing at 110 ℃ for 0.2h to obtain a conductive carbon film semi-finished product with the conductive carbon layer thickness of 7 mu m, coating the conductive carbon paste on the second surface of the high-temperature-resistant conductive substrate layer, curing at 110 ℃ for 0.2h, and coating the conductive carbon film semi-finished product with the conductive carbon layer dry film thickness of 7 mu m to obtain the conductive carbon film semi-finished product with the conductive carbon layer coated on both sides.
Fifth, rolling and manufacturing the high-temperature-resistant flexible conductive carbon film: and rolling the semi-finished conductive carbon film with the conductive carbon layers coated on both sides at normal temperature through a roll squeezer to obtain the high-temperature-resistant flexible composite conductive film.
Example 3
The structure of the high temperature-resistant flexible composite conductive film is the same as that of the high temperature-resistant flexible composite conductive film of example 1.
The preparation method of the high-temperature-resistant flexible composite conductive film comprises the following steps:
step one, preparing conductive polyimide slurry: mixing 0.3 part by weight of conductive carbon black with the particle size of 25nm, 0.3 part by weight of borosilicate hollow glass microspheres with the particle size of 50 mu m and 400 parts by weight of polyimide varnish, wherein the solid content of the polyimide varnish is 30%, the viscosity of the polyimide varnish is 2500cps, and then dispersing for 1h at the dispersion speed of 1600rpm/min to obtain conductive polyimide slurry;
step two, preparing a high-temperature-resistant conductive substrate layer: coating conductive polyimide slurry on a PET double-sided silicon release film with a release force of 5-10 g at 50 mu m by using a coating machine, baking at 110 ℃ to remove most of solvent to obtain a semi-cured substrate layer, peeling the PET double-sided silicon release film, spraying carboxylated polystyrene microspheres on the upper and lower surfaces of the semi-cured substrate layer, baking at 160 ℃, imidizing to obtain a substrate layer with a dry film thickness of 8 mu m, etching the cured substrate layer by using hydrofluoric acid to leave cavities after etching the hollow glass spheres, repeatedly soaking the etched substrate layer for 5 times (replacing water after each soaking), and drying at 100 ℃ after soaking to obtain the conductive polyimide substrate layer with a microporous structure;
step three, preparing conductive slurry:
s1, uniformly mixing 20 parts by weight of crystalline flake graphite powder with the particle size of 250 mu m, 2 parts by weight of carboxymethyl starch adhesive and 200 parts by weight of N-methyl pyrrolidone, and grinding for 3 hours at the speed of 6000rpm/min by using a vertical sand mill to obtain C1 slurry;
s2, adding 10 parts by weight of carboxyl carbon nano tubes with the tube diameter of 30nm and the tube length of 20 mu m into the C1 slurry, uniformly mixing 3 parts by weight of dispersing agent and 100 parts by weight of water, wherein the dispersing agent is a mixture of vinyl pyrrolidone and vinyl acetate copolymer according to the mass ratio of 1:1, and homogenizing for 12 times by using a high-pressure homogenizer at the pressure of 800bar to obtain C2 slurry;
s3, adding 5 parts by weight of conductive carbon black into the C2 slurry, uniformly mixing, and homogenizing for 3 times by using a high-pressure homogenizer at a pressure of 800bar to obtain C3 slurry;
s4, adding 0.5 part by weight of polycarbodiimide into the C3 sizing agent, dispersing for 1h at the speed of 1000rpm/min by adopting a high-speed dispersing machine, wherein the dispersing temperature is less than 15 ℃, and filtering the sizing agent through 150-mesh gauze after dispersing to prepare the conductive sizing agent.
Step four, preparing a conductive carbon layer: and coating the conductive paste on the first surface of the high-temperature-resistant conductive substrate layer, curing at 110 ℃ for 0.5h to obtain a conductive carbon film semi-finished product with the conductive carbon layer thickness of 25 mu m, coating the conductive carbon paste on the second surface of the high-temperature-resistant conductive substrate layer, curing at 110 ℃ for 0.5h, and coating the conductive carbon film semi-finished product with the conductive carbon layer dry film thickness of 25 mu m to obtain the conductive carbon film semi-finished product with the conductive carbon layer coated on both sides.
Fifth, rolling and manufacturing the high-temperature-resistant flexible conductive carbon film: and (3) carrying out hot rolling at 80 ℃ on the conductive carbon film semi-finished product coated with the conductive carbon layers on the two sides by a roll squeezer to obtain the high-temperature-resistant flexible composite conductive film.
Comparative example 1
The preparation method of the composite conductive film comprises the following steps:
step one, preparing conductive polyimide slurry: mixing 1 part by weight of nano conductive carbon black with the particle size of 25nm with 400 parts by weight of polyimide varnish, wherein the solid content of the polyimide varnish is 25%, the viscosity is 1200cps, and then dispersing for 1h at the dispersion speed of 1600rpm/min to obtain conductive polyimide slurry;
step two, preparing a high-temperature-resistant conductive substrate layer: coating conductive polyimide slurry on a PET double-sided silicon release film with a release force of 5-10 g at 75 mu m by using a coating machine, baking at 95 ℃ to remove most of solvent to obtain a semi-cured substrate layer, peeling the PET double-sided silicon release film, spraying carboxylated polystyrene microspheres on the upper and lower surfaces of the semi-cured substrate layer, baking at 160 ℃ at high temperature, and imidizing to obtain a conductive polyimide substrate layer with a dry film thickness of 12 mu m;
step three, preparing conductive slurry:
s1, uniformly mixing 30 parts by weight of flake graphite powder with the particle size of 50 mu m, 10 parts by weight of carboxymethyl cellulose adhesive and 300 parts by weight of water, and grinding for 6 hours at the speed of 3000rpm/min by using a vertical sand mill to obtain C1 slurry;
s2, adding 15 parts by weight of carboxyl carbon nano tubes with the tube diameter of 20nm and the tube length of 10 mu m into the C1 slurry, uniformly mixing 6 parts by weight of dispersing agent and 200 parts by weight of water, wherein the dispersing agent is a mixture of vinyl pyrrolidone and vinyl acetate copolymer according to the mass ratio of 1:1, and homogenizing for 6 times by using a high-pressure homogenizer at the pressure of 800bar to obtain C2 slurry;
s3, adding 10 parts by weight of conductive carbon black into the C2 slurry, uniformly mixing, and homogenizing for 3 times by using a high-pressure homogenizer at a pressure of 600bar to obtain C3 slurry;
s4, adding 2 parts by weight of polycarbodiimide into the C3 sizing agent, dispersing for 0.5h at the speed of 1600rpm/min by adopting a high-speed dispersing machine, wherein the dispersing temperature is less than 15 ℃, and filtering the sizing agent through 150-mesh gauze after dispersing to prepare the conductive sizing agent.
Step four, preparing a conductive carbon layer: coating the conductive paste on the first surface of the high-temperature-resistant conductive substrate layer, curing at 110 ℃ for 0.2h to obtain a conductive carbon film semi-finished product with the conductive carbon layer thickness of 15 mu m, coating the conductive carbon paste on the second surface of the high-temperature-resistant conductive substrate layer, curing at 110 ℃ for 0.2h, and coating the conductive carbon film semi-finished product with the conductive carbon layer dry film thickness of 15 mu m to obtain the conductive carbon film semi-finished product with the conductive carbon layer coated on both sides.
Fifth, rolling and manufacturing the high-temperature-resistant flexible conductive carbon film: and rolling the semi-finished conductive carbon film with the conductive carbon layers coated on both sides at normal temperature through a roll squeezer to obtain the high-temperature-resistant flexible composite conductive film.
Comparative example 2
The preparation method of the composite conductive film comprises the following steps:
step one, preparing conductive polyimide slurry: mixing 1 part by weight of nano conductive carbon black with the particle size of 25nm, 0.5 part by weight of sodium-calcium hollow glass microspheres with the particle size of 5 mu m and 400 parts by weight of polyimide varnish, wherein the solid content of the polyimide varnish is 25%, the viscosity is 1200cps, and then dispersing for 1h at the dispersion speed of 1600rpm/min to obtain conductive polyimide slurry;
step two, preparing a high-temperature-resistant conductive substrate layer: coating conductive polyimide slurry on a PET double-sided silicon release film with a release force of 5-10 g at 75 mu m by using a coating machine, baking at 95 ℃ to remove most of solvent to obtain a semi-cured substrate layer, baking at 160 ℃ to obtain a substrate layer with a dry film thickness of 12 mu m after imidization, etching the cured substrate layer by using hydrofluoric acid to etch hollow glass spheres, leaving micropores after etching, repeatedly soaking the etched film for 5 times (changing water after each soaking), and drying at 100 ℃ after soaking to obtain the conductive polyimide substrate layer with a microporous structure;
step three, preparing conductive slurry:
s1, uniformly mixing 30 parts by weight of flake graphite powder with the particle size of 50 mu m, 10 parts by weight of carboxymethyl cellulose adhesive and 300 parts by weight of water, and grinding for 6 hours at the speed of 3000rpm/min by using a vertical sand mill to obtain C1 slurry;
s2, adding 15 parts by weight of carboxyl carbon nano tubes with the tube diameter of 20nm and the tube length of 10 mu m into the C1 slurry, uniformly mixing 6 parts by weight of dispersing agent and 200 parts by weight of water, wherein the dispersing agent is a mixture of vinyl pyrrolidone and vinyl acetate copolymer according to the mass ratio of 1:1, and homogenizing for 6 times by using a high-pressure homogenizer at the pressure of 800bar to obtain C2 slurry;
s3, adding 10 parts by weight of conductive carbon black into the C2 slurry, uniformly mixing, and homogenizing for 3 times by using a high-pressure homogenizer at a pressure of 600bar to obtain C3 slurry;
s4, adding 2 parts by weight of polycarbodiimide into the C3 sizing agent, dispersing for 0.5h at the speed of 1600rpm/min by adopting a high-speed dispersing machine, wherein the dispersing temperature is less than 15 ℃, and filtering the sizing agent through 150-mesh gauze after dispersing to prepare the conductive sizing agent.
Step four, preparing a conductive carbon layer: coating the conductive paste on the first surface of the high-temperature-resistant conductive substrate layer, curing at 110 ℃ for 0.2h to obtain a conductive carbon film semi-finished product with the conductive carbon layer thickness of 15 mu m, coating the conductive carbon paste on the second surface of the high-temperature-resistant conductive substrate layer, curing at 110 ℃ for 0.2h, and coating the conductive carbon film semi-finished product with the conductive carbon layer dry film thickness of 15 mu m to obtain the conductive carbon film semi-finished product with the conductive carbon layer coated on both sides.
Fifth, rolling and manufacturing the high-temperature-resistant flexible conductive carbon film: and rolling the semi-finished conductive carbon film with the conductive carbon layers coated on both sides at normal temperature through a roll squeezer to obtain the high-temperature-resistant flexible composite conductive film.
Comparative example 3
The preparation method of the composite conductive film comprises the following steps:
step one, preparing conductive polyimide slurry: mixing 0.025 parts by weight of ketjen black with the particle size of 30nm, 0.025 parts by weight of borosilicate hollow glass microspheres with the particle size of 50 mu m and 500 parts by weight of polyimide varnish, wherein the solid content of the polyimide varnish is 20%, the viscosity of the polyimide varnish is 800cps, and then dispersing for 1h at the dispersion speed of 1600rpm/min to obtain conductive polyimide slurry;
step two, preparing a high-temperature-resistant conductive substrate layer: coating conductive polyimide slurry on a PET double-sided silicon release film with a release force of 5-10 g at 50 mu m by using a coating machine, baking at 110 ℃ to remove most of solvent to obtain a semi-cured substrate layer, peeling the PET double-sided silicon release film, spraying carboxylated polystyrene microspheres on the upper and lower surfaces of the semi-cured substrate layer, baking at 160 ℃, imidizing to obtain a substrate layer with a dry film thickness of 25 mu m, etching the cured substrate layer by using hydrofluoric acid, etching hollow glass spheres to leave micropores, repeatedly soaking the etched substrate layer for 5 times (replacing water after each soaking), and drying at 100 ℃ to obtain the conductive polyimide substrate layer with a microporous structure;
step three, preparing conductive slurry:
s1, uniformly mixing 30 parts by weight of crystalline flake graphite powder with the particle size of 150 mu m, 10 parts by weight of carboxymethyl cellulose adhesive and 400 parts by weight of water, and grinding for 6 hours at the speed of 3500rpm/min by using a vertical sand mill to obtain C1 slurry;
s2, adding 10 parts by weight of carboxyl carbon nano tubes with the tube diameter of 50nm and the tube length of 15 mu m into the C1 slurry, uniformly mixing the carboxyl carbon nano tubes with 6 parts by weight of polyvinylpyrrolidone and 100 parts by weight of water, and homogenizing the mixture for 6 times by using a high-pressure homogenizer at the pressure of 1000bar to obtain C2 slurry;
s3, adding 10 parts by weight of conductive carbon black into the C2 slurry, uniformly mixing, and homogenizing for 3 times by using a high-pressure homogenizer at a pressure of 600bar to obtain C3 slurry;
and S4, filtering the C3 slurry through 150-mesh gauze to obtain the conductive slurry.
Step four, preparing a conductive carbon layer: and coating the conductive paste on the first surface of the high-temperature-resistant conductive substrate layer, curing at 110 ℃ for 0.2h to obtain a conductive carbon film semi-finished product with the conductive carbon layer thickness of 7 mu m, coating the conductive carbon paste on the second surface of the high-temperature-resistant conductive substrate layer, curing at 110 ℃ for 0.2h, and coating the conductive carbon film semi-finished product with the conductive carbon layer dry film thickness of 7 mu m to obtain the conductive carbon film semi-finished product with the conductive carbon layer coated on both sides.
Fifth, rolling and manufacturing the high-temperature-resistant flexible conductive carbon film: and rolling the semi-finished conductive carbon film with the conductive carbon layers coated on both sides at normal temperature through a roll squeezer to obtain the high-temperature-resistant flexible composite conductive film.
Performance testing
1. Performance test of conductive paste prepared in step three of examples 1 to 3 and comparative examples 1 to 3:
1. conductive performance test of conductive paste: coating the conductive paste prepared in the step three of the examples 1-3 and the comparative examples 1-3 in a PET substrate, controlling the thickness of a wet film through a coating slit gap, curing to obtain a conductive carbon layer, testing the thickness by a film thickness meter, and then testing the conductivity by four probes;
2. and (3) testing the solid content of the conductive paste: the conductive pastes prepared in the steps three of examples 1-3 and comparative examples 1-3 were tested by using a paste solid content tester according to the GB1725-1979 paint solid content measurement method;
3. conductive carbon layer powder removal test: the method comprises the steps of lightly wiping the surface of a coating by using paper towels, observing whether the coating is wiped out or not, and judging whether the coating is subjected to powder removal or not, wherein the specific operation is to uniformly coat conductive slurry on a sample plate, solidify and dry the conductive slurry, cover two layers of white cotton cloth on a grinding head for a test of a scrubbing resistance tester, place the dried sample plate on the scrubbing resistance tester for reciprocating wiping, take down the cotton cloth, visually observe the color difference of the cotton cloth before and after wiping, and judge the degree of powder removal severity if the white cotton cloth is obviously black; whereas the more slight the run off is if there is little or only a small amount of grey on the white cotton cloth.
2. And (3) testing the performance of the high-temperature-resistant flexible composite conductive film:
1. and (3) testing the conductivity of the high-temperature-resistant flexible composite conductive film: four-probe testing of the conductive performance was performed on the high-temperature-resistant flexible composite conductive films obtained by rolling in examples 1 to 3 and comparative examples 1 to 3;
2. high temperature resistant flexibility composite conductive film flexibility test: the flexibility tester is adopted to test according to the standard of GB1731 paint film flexibility test, namely, a 1mm rigid roller is used as the axle center, the sample is folded in half for 1 time, and whether the sample is cracked or peeled off is observed.
3. High temperature flexibility resistance test of composite conductive film: the two ends of the sample are fixed on an HM-8666 bending resistance tester with a force of 0.98N, and the bending test is started under the condition that the bending radius is 5mm and the bending angle is 180 degrees, so that the bending times of the sample are tested.
4. And (3) water-soaking resistance test: cutting a high-temperature-resistant flexible composite conductive film sample into square pieces with the length of 5cm, putting the square pieces into a container such as a beaker filled with deionized water, completely soaking the sample in water, standing for 72 hours, taking out the conductive film sample, and observing the appearance condition of the soaked conductive film sample.
TABLE 1 Performance test of conductive pastes prepared in step three of examples 1-3 and comparative examples 1-3
As can be seen from Table 1, the conductive paste obtained by adjusting the normal components and the preparation process of the embodiment has no large amount of film forming resin such as epoxy resin, polyurethane and the like, and the conductive paste is prepared by dispersing and bonding the carbon-based filler by using the adhesive to form a coating, so that the content of conductive carbon is greatly improved, the obtained conductive paste can ensure that the coating is not destoner, the resistivity of the coating is extremely low and is far lower than 0.01 ohm cm, and good performance is provided for preparing the conductive carbon film.
Table 2 test of composite conductive film properties
| Example 1 | Example 2 | Example 3 | Comparative example 1 | Comparative example 2 | Comparative example 3 | |
| Thickness before rolling (μm) | 42 | 39 | 58 | 42 | 42 | 39 |
| Thickness after rolling (μm) | 36 | 35 | 53 | 39 | 36 | 35 |
| Bending resistance times (times) | >1000 | >1000 | >1000 | >1000 | >1000 | >1000 |
| Flexibility of the product | Intact (good) | Intact (good) | Intact (good) | Slight cracking and falling off | Slight cracking and falling off | Intact (good) |
| Resistivity after roll | 0.011 | 0.009 | 0.013 | 0.019 | 0.023 | 0.02 |
| Water-resistant bubble | Intact (good) | Intact (good) | Intact (good) | Slightly skinning and swelling | Skinning and swelling | Slightly skinning and swelling |
Examples 1-3 in table 2 are composite conductive carbon films prepared by normal formulation and process, comparative example 1 is a conductive polyimide substrate layer prepared without adding hollow glass microspheres, and the obtained substrate layer has no microporous structure; comparative example 2 is a method in which carboxylated polyethylene benzene microspheres are not sprayed on the surface of a polyimide substrate layer; comparative example 3 is a composite conductive film made using a conductive paste without the addition of polycarbodiimide.
Through thickness contrast before the roll-in can know, can make the conductive carbon layer form dense carbon layer after the roll-in, design substrate has the micropore structure after moreover, and conductive carbon layer combines more compactly with conductive polyimide layer, and conductive carbon layer can realize more compact structure through the roll-in. As can be seen from the comparison of the example 1 and the comparative example 1, the design of the microporous structure of the base material further improves the binding force of the conductive carbon layer, so that the obtained composite conductive carbon film has thinner thickness and better flexibility. From the comparison of the example 1 and the comparative example 2, the surface of the base material is subjected to the spraying treatment of the carboxylated polystyrene microsphere, and the carboxylated polystyrene microsphere can be used as an anchor point to react with the crosslinking auxiliary agent of the conductive paste, so that better improvement of the adhesive force is realized. As can be seen from the comparison of example 2 and comparative example 3, a conductive carbon layer excellent in conductivity and film forming effect was produced by formulating a formulation of a highly conductive carbon-based conductive paste.
The invention designs and prepares the conductive polyimide film by utilizing the micropore structure of the hollow glass microsphere, and carries out surface spraying carboxylated polystyrene treatment on the conductive substrate film, designs a plurality of anchor points, takes the anchor points as the substrate layer to carry out upper and lower surface coating conductive carbon layers, realizes tight combination between the conductive carbon layers and the substrate layer, ensures good combination fastness between the substrate layer and the conductive layer by rolling, obtains a compact composite conductive carbon film, avoids separation and falling phenomena between the substrate layer and the conductive layer due to insufficient combination fastness, and simultaneously has excellent conductivity and wider application field.
The foregoing examples illustrate only a few embodiments of the invention and are described in detail herein without thereby limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (10)
1. The high-temperature-resistant flexible composite conductive film is characterized by comprising a high-temperature-resistant conductive substrate layer and a conductive carbon layer coated on the surface of the high-temperature-resistant conductive substrate layer; the surface of the high-temperature-resistant conductive substrate layer is distributed with a plurality of microporous structures, and the surface of the high-temperature-resistant conductive substrate layer is provided with a plurality of polystyrene microspheres.
2. The high temperature resistant flexible composite conductive film of claim 1, wherein the conductive carbon layer is prepared from a conductive paste; the conductive paste comprises the following components in parts by weight:
the adhesive is at least one of carboxymethyl cellulose and carboxymethyl starch.
3. The high temperature resistant flexible composite conductive film of claim 2, wherein the dispersant is at least one of polyvinyl alcohol, polyvinylpyrrolidone, vinylpyrrolidone, and vinyl acetate copolymer.
4. The high temperature resistant flexible composite conductive film of claim 2, wherein the solvent is deionized water or N-methylpyrrolidone.
5. The high-temperature-resistant flexible composite conductive film according to claim 2, wherein the conductive paste is prepared by the following method:
s1, uniformly mixing graphite powder, an adhesive and a part of solvent, and grinding for 0.5-6 hours at the speed of 1000-6000rpm/min by using grinding equipment to obtain C1 slurry;
s2, adding a carboxyl carbon nano tube, a dispersing agent and the rest solvent into the C1 slurry, and homogenizing for 6-12 times by using a high-pressure homogenizer at a pressure of 600-1000bar to obtain C2 slurry;
s3, adding conductive carbon black into the C2 slurry, and homogenizing for 3-6 times by using a high-pressure homogenizer at a pressure of 600-1000bar to obtain C3 slurry;
s4, adding polycarbodiimide into the C3 slurry, and dispersing for 0.5-1h at a speed of 1000-1600rpm/min by adopting a high-speed dispersing machine, wherein the dispersing temperature is less than 15 ℃, so as to obtain the conductive slurry.
6. The high temperature resistant flexible composite conductive film according to claim 1, wherein the preparation method of the high temperature resistant conductive substrate layer comprises the following steps: adding glass microspheres and conductive powder into polyimide varnish solution, mixing uniformly to form conductive polyimide slurry, coating the conductive polyimide slurry on a PET release film to form a substrate layer, spraying polystyrene microspheres on the surface of the substrate layer, and etching the cured substrate layer by using hydrofluoric acid after the substrate layer is cured to obtain the high-temperature-resistant conductive substrate layer with a micropore structure.
7. The method for preparing the high-temperature-resistant flexible composite conductive film according to claim 6, wherein the method comprises the steps of firstly baking at 80-110 ℃ after the conductive polyimide slurry is coated on the PET release film, removing most of solvent to obtain a semi-cured substrate layer, spraying polystyrene microspheres on the surface of the semi-cured substrate layer, baking at 120-160 ℃ to obtain the cured substrate layer, and etching the cured substrate layer by hydrofluoric acid to obtain the high-temperature-resistant conductive substrate layer with a micropore structure.
8. The high temperature resistant flexible composite conductive film of claim 1, wherein the polystyrene microspheres are carboxylated polystyrene microspheres.
9. The high-temperature-resistant flexible composite conductive film according to claim 6, wherein the glass microspheres are hollow glass microspheres made of soda lime glass or borosilicate glass.
10. The high temperature resistant flexible composite conductive film according to claim 6, wherein the glass microspheres have a particle size of 5-50 μm.
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