CN113026412B - Method for preparing heat-conducting graphite film by utilizing artificial graphite film leftover material - Google Patents

Method for preparing heat-conducting graphite film by utilizing artificial graphite film leftover material Download PDF

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CN113026412B
CN113026412B CN202110384369.7A CN202110384369A CN113026412B CN 113026412 B CN113026412 B CN 113026412B CN 202110384369 A CN202110384369 A CN 202110384369A CN 113026412 B CN113026412 B CN 113026412B
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graphite film
heat
conducting
hydrophilic
preparing
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CN113026412A (en
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刘占军
陶则超
李香粉
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Shanxi Institute of Coal Chemistry of CAS
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Shanxi Institute of Coal Chemistry of CAS
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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
    • D21H13/36—Inorganic fibres or flakes
    • D21H13/46—Non-siliceous fibres, e.g. from metal oxides
    • D21H13/50—Carbon fibres
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H15/00—Pulp or paper, comprising fibres or web-forming material characterised by features other than their chemical constitution
    • D21H15/02—Pulp or paper, comprising fibres or web-forming material characterised by features other than their chemical constitution characterised by configuration
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20—Macromolecular organic compounds
    • D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
    • D21H17/24—Polysaccharides
    • D21H17/25—Cellulose
    • D21H17/26—Ethers thereof
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/06—Paper forming aids
    • D21H21/08—Dispersing agents for fibres

Abstract

The invention relates to a method for preparing a heat-conducting graphite film by utilizing artificial graphite film leftover materials, belongs to the technical field of heat-conducting materials, and solves the technical problem of recycling the graphite film leftover materials after high-temperature graphitization treatment. The obtained heat-conducting graphite film has low additive content, and the graphite fibers form a heat-conducting path through mutual boundary, so that the obtained heat-conducting graphite film has high heat conductivity. The heat-conducting graphite film obtained by the method provided by the invention has higher volume density and heat conductivity, is positioned between the artificial graphite film and the natural graphite film in thickness and heat-conducting capacity, fills the blank of the area, and enriches the selection of heat control design.

Description

Method for preparing heat-conducting graphite film by utilizing artificial graphite film leftover material
Technical Field
The invention belongs to the technical field of heat conduction materials, and particularly relates to a method for preparing a heat conduction graphite film by utilizing artificial graphite film leftover materials.
Background
The artificial graphite film is a high-crystallinity graphite film formed by using a polyimide film as a precursor through a high-temperature heat treatment mode, the plane thermal conductivity of the artificial graphite film can reach more than 1500W/m.K, and the thickness of the artificial graphite film is 20-60 mu m mostly. In the process of producing the artificial graphite film, a large amount of waste thin-strip-shaped artificial graphite film leftover materials can be generated by processes of slicing, edge cutting and the like, the thin-strip-shaped artificial graphite film leftover materials belong to solid wastes, and the treatment and the recovery of the thin-strip-shaped artificial graphite film leftover materials become common problems in the industry.
The method has the theoretical feasibility of assembling the existing commercial artificial graphite film or the artificial graphite film leftover material into a compound with larger thickness by taking the existing commercial artificial graphite film or the artificial graphite film leftover material as a raw material. However, the artificial graphite film and the leftover materials thereof are all subjected to high-temperature graphitization treatment, the surface of the graphite film hardly contains functional groups, and the chemical reaction activity is extremely low. Therefore, it is difficult to directly assemble a composite having a certain thickness and strength by simply using the graphite thin film as a raw material.
In addition to this, researchers in the field now typically will carbon fiber paper, that is, willThe chopped carbon fibers are added into the paper pulp, and the paper-making process is utilized to prepare the carbon fiber paper-like sheet without orientation. Yangyonggang (Chinese patent application number: 200410012492.2) and other people add chopped fibers into paper pulp and prepare the paper with the bulk density of 0.45g/cm by a wet papermaking process3The carbon fiber sheet with the thickness of 0.1-0.5 mm has the conductivity of 0.05 omega cm; in addition, other researchers (Chinese patent publication No. CN 106436439A) add resin binder to enhance the bonding strength during the wet papermaking process. However, most of the carbon fiber paper prepared by the method is porous material, and the volume density is 0.45g/cm3The thermal conductivity is generally below 20W/m.K, the main application is a fuel cell diaphragm, an electrothermal material and the like, the carbon fiber paper does not have the thermal conductivity performance, and the conventional carbon fiber paper cannot provide the thermal conductivity performance.
Disclosure of Invention
In order to overcome the defects of the prior art and solve the technical problem of recycling the leftover materials of the graphite film after high-temperature graphitization treatment, the invention provides a method for preparing a heat-conducting graphite film by utilizing the leftover materials of an artificial graphite film. Compared with a natural graphite film, the heat-conducting graphite film obtained by the method provided by the invention has higher volume density and heat conductivity.
The invention is realized by the following technical scheme.
A method for preparing a heat-conducting graphite film by utilizing artificial graphite film leftover materials comprises the following steps:
s1, sequentially crushing and hydrophilically modifying the artificial graphite film leftover materials to obtain hydrophilic short-cut graphite fibers, wherein the length of each hydrophilic short-cut graphite fiber is 6-10 mm;
s2, uniformly mixing the hydrophilic chopped graphite fibers prepared in the step S1, paper pulp, a dispersing agent and water, and defibering the obtained mixture to obtain mixed slurry; the mass ratio of the total mass of the hydrophilic chopped graphite fibers, the paper pulp and the dispersing agent to water is 1 (1-5), the mass of the hydrophilic chopped graphite fibers accounts for 60-90% of the total mass of the hydrophilic chopped graphite fibers and the paper pulp, and the mass of the dispersing agent accounts for 1-5% of the total mass of the hydrophilic chopped graphite fibers and the paper pulp;
s3, sequentially carrying out wire papermaking and primary drying on the mixed slurry prepared in the step S2 to obtain base paper;
s4, applying a binder on the surface of the base paper prepared in the step S3, wherein the mass ratio of solute in the binder to the base paper is (1-10): 100, laminating the raw paper with the surface applied with the binding agent, and then sequentially extruding and drying for the second time to obtain a heat-conducting graphite film; the direction of the extrusion is perpendicular to the paper surface.
Further, in the step S1, the hydrophilic modification is a coupling agent modification, an oxygen plasma modification, or a nitric acid modification.
Further, in step S2, the dispersant is carboxymethyl cellulose or carboxyethyl cellulose.
Further, in the step S2, the defibering is performed under the stirring condition, the stirring speed is 1000 to 5000rpm, and the stirring time is 1 to 30 min.
Further, in the step S3, the thickness of the prepared base paper is 0.3 to 1.5 mm.
Further, in the step S4, the adhesive is a polyvinyl alcohol aqueous solution, and the mass percentage of the polyvinyl alcohol aqueous solution is 3 to 10 wt.%.
Further, in the step S4, the deformation amount of the base paper after the extrusion is 33 to 70%.
Further, the drying temperature of the primary drying in the step S3 and the drying temperature of the secondary drying in the step S4 are both 80-130 ℃, and the drying time is 10-100 min.
Further, the thickness of the heat-conducting graphite film prepared in the step S4 is 0.1-1 mm, the volume density is 0.3-0.8 g/cm3, and the thermal conductivity is 400-600W/m.K.
Compared with the prior art, the invention has the beneficial effects that:
the method comprises the steps of processing the artificial graphite leftover into short fibers with the length of 6-10 mm, then preparing raw paper with a certain thickness through a wet papermaking process, pressing the raw paper into a compact sheet shape in an extrusion mode, and finally drying the compact sheet shape to form the heat-conducting graphite film. The graphite fibers in the obtained heat-conducting graphite film form a heat-conducting path through mutual boundary, so that the obtained heat-conducting graphite film has high heat conductivity. The heat-conducting graphite film prepared by the method provided by the invention is positioned between the artificial graphite film and the natural graphite film in thickness and heat-conducting capacity, so that the blank of the area is filled, and the selection of heat control design is enriched.
Experimental results show that the thickness of the heat-conducting graphite film obtained by the method provided by the invention reaches 0.1-0.7 mm, and the volume density reaches 0.51-0.80 g/cm3The thermal conductivity reaches 443-565W/m.K, the volume density is high, the thermal conductivity is excellent, and the performance requirement of the heat conduction material can be met.
Detailed Description
The invention provides a method for preparing a heat-conducting graphite film by utilizing artificial graphite film leftover materials, which comprises the following steps of:
s1, sequentially crushing and hydrophilically modifying the leftover materials of the artificial graphite film to obtain hydrophilic chopped graphite fibers; the length of the hydrophilic short-cut graphite fiber is 6-10 mm;
s2, mixing the hydrophilic chopped graphite fibers, paper pulp, a dispersing agent and water, and defibering the obtained mixture to obtain mixed slurry;
s3, sequentially carrying out wire papermaking and primary drying on the mixed slurry to obtain base paper;
s4, after the surface of the base paper is applied with the binder, the obtained base paper with the surface applied with the binder is laminated and then sequentially extruded and secondarily dried to obtain the heat-conducting graphite film; the direction of the extrusion is perpendicular to the paper surface.
In the present invention, unless otherwise specified, each raw material in the process is a commercially available product well known to those skilled in the art.
The method comprises the following steps of sequentially crushing and hydrophilically modifying leftover materials of the artificial graphite film to obtain hydrophilic chopped graphite fibers; the length of the hydrophilic short-cut graphite fiber is 6-10 mm.
The source of the artificial graphite film leftover material is not particularly limited in the invention, and the source known by the person skilled in the art can be adopted.
The artificial graphite film may be crushed into chopped graphite fibers by the method of the present invention. In the present invention, the hydrophilic modification preferably includes a coupling agent modification, an oxygen plasma modification or a nitric acid modification.
In the present invention, the coupling agent is preferably modified by immersing the chopped graphite fibers in the coupling agent and then drying the fibers in an anhydrous environment. In the present invention, the coupling agent in the modification of the coupling agent is preferably a silane coupling agent, specifically, silane coupling agent K-550. In the invention, the mass ratio of the coupling agent to the chopped graphite fibers is preferably (1-5): 100. in the invention, the drying temperature is preferably 80-130 ℃, and more preferably 120 ℃; the time is preferably 10 to 50min, and more preferably 10 min.
In the invention, the time for modifying the oxygen plasma is preferably 50 to 70s, and more preferably 60 s. In the present invention, the method of oxygen plasma modification is preferably a plasma irradiation method; the plasma irradiation method is not particularly limited in the present invention, and a plasma irradiation method known to those skilled in the art may be used.
In the present invention, the nitric acid modification method is preferably performed by immersing the chopped graphite fibers in nitric acid and then washing the fibers to neutrality. In the invention, the concentration of the nitric acid is preferably 65-70 wt.%, and more preferably 68 wt.%. In the invention, the soaking time is preferably 1-2 h. The cleaning method of the present invention is not particularly limited, and a cleaning method known to those skilled in the art may be used.
According to the invention, through hydrophilic modification, the number of polar functional groups on the surface of the chopped graphite fiber is increased, and the hydrophilic performance of the chopped graphite fiber is improved.
In the invention, the length of the modified graphite fiber is 6-10 mm, preferably 7-9 mm.
After the modified graphite fiber is obtained, the modified graphite fiber, paper pulp, a dispersing agent and water are mixed, and the obtained mixture is defibered to obtain mixed slurry.
In the present invention, the mass of the modified graphite fiber is preferably 60 to 90%, more preferably 65 to 85% of the total mass of the modified graphite fiber and the pulp. In the present invention, the mass ratio of the total mass of the hydrophilic chopped graphite fibers, pulp, and dispersant to water is preferably 1: (1-5), more preferably 1: (1.5-4.5). In the present invention, the concentration of the pulp is preferably 2 to 5wt.%, more preferably 3 to 4wt.%, most preferably 3 wt.%. The source of the pulp is not particularly limited in the present invention, and any pulp source known to those skilled in the art may be used, and specifically, the pulp is commercially available. In the present invention, the dispersant is preferably carboxymethyl cellulose or carboxyethyl cellulose. In the present invention, the mass of the dispersant is 1 to 5%, more preferably 1 to 4%, of the total mass of the modified graphite fiber and the pulp. The mixing method is not particularly limited in the present invention, and mixing known to those skilled in the art, such as stirring, may be employed.
In the present invention, the defibering is preferably performed under stirring; the stirring speed is preferably 1000-5000 rpm, and more preferably 2000-4000 rpm; the time is preferably 1 to 30min, and more preferably 10 to 30 min.
After the mixed pulp is obtained, the mixed pulp is sequentially subjected to wire papermaking and primary drying to obtain the base paper.
The process of the wire papermaking in the present invention is not particularly limited, and a wire papermaking process in wet papermaking known to those skilled in the art may be used.
In the invention, the temperature of the primary drying is preferably 80-130 ℃, and more preferably 90-120 ℃; the time is preferably 10 to 100min, and more preferably 30 to 70 min. In the invention, the thickness of each piece of base paper is preferably 0.3-1.5 mm, and more preferably 0.4-1.3 mm. In the present invention, the primary drying apparatus is preferably an oven.
After the base paper is obtained, after the surface of the base paper is applied with the adhesive, the obtained base paper with the surface applied with the adhesive is laminated and then sequentially extruded and secondarily dried to obtain the heat-conducting graphite film; the direction of the extrusion is perpendicular to the paper surface.
In the present invention, the binder is preferably an aqueous polyvinyl alcohol solution; the mass percentage of the polyvinyl alcohol aqueous solution is preferably 3-10 wt.%, and more preferably 4-8 wt.%. In the invention, the mass ratio of the solute to the base paper in the binder is preferably (1-10): 100, more preferably (2-5): 100. in the present invention, the method of applying the binder to the surface of the base paper is preferably spray coating; the spray coating is not particularly limited in the present invention, and a spray coating process known to those skilled in the art may be used.
In the present invention, the extrusion apparatus is preferably a two-roll press. The invention controls the thickness of the base paper after extrusion by adjusting the gap between the two rollers in the double-roller rolling machine. In the present invention, the deformation amount of the base paper after extrusion is preferably 33 to 70%.
In the invention, the temperature of the secondary drying is preferably 80-130 ℃, and more preferably 90-120 ℃; the time is preferably 10 to 100min, and more preferably 30 to 70 min. In the present invention, the secondary drying apparatus is preferably an oven.
In the invention, the thickness of the heat-conducting graphite film is preferably 0.1-1 mm, and more preferably 0.1-0.7 mm; the preferred volume density is 0.3-0.8 g/cm3More preferably 0.5 to 0.8g/cm3(ii) a The thermal conductivity is preferably 400 to 600W/mK, and more preferably 440 to 570W/mK.
The heat-conducting graphite film prepared by the method provided by the invention is positioned between the artificial graphite film and the natural graphite film in thickness and heat-conducting capacity (the thickness of the artificial graphite film is less than 60 mu m, the heat conductivity is 700-1500W/m.K, the thickness of the natural graphite film is 0.1-0.3 mm, and the heat conductivity is only 300W/m.K), the blank of the area is filled, the selection of thermal control design is enriched, and the heat-conducting graphite film can be used for temperature equalization and heat dissipation of electronic equipment.
In order to further illustrate the present invention, the following examples are provided to describe the method for preparing the heat conductive graphite film by using the offcuts of the artificial graphite film in detail, but they should not be construed as limiting the scope of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The reagents used in the following examples are all commercially available.
Example 1
S1, crushing the artificial graphite film leftover into chopped graphite fibers, soaking the chopped graphite fibers in a silane coupling agent K-550, and drying in an anhydrous environment, wherein the silane coupling agent K-550 accounts for 1 wt% of the artificial graphite film leftover, so as to obtain the hydrophilic chopped graphite fibers with the length of 6-10 mm;
s2, mixing 60 parts by mass of hydrophilic chopped graphite fibers, 40 parts by mass of softwood kraft pulp (with a concentration of 3 wt.%) and 5 parts by mass of carboxymethyl cellulose, and stirring the obtained mixture at a rotating speed of 3000rpm for 30min for defibering to obtain mixed slurry;
s3, performing net part papermaking on the mixed pulp, and drying for 1h at 120 ℃ to obtain base paper with the thickness of 1.5 mm;
s4, spraying a binder polyvinyl alcohol aqueous solution with the mass percentage of 5wt.% on the surface of the obtained base paper, wherein the mass ratio of the binder to the base paper is 3: 100, extruding the base paper with the surface applied with the binder on a double-roller rolling machine to obtain a sheet with the thickness of 0.7mm, and finally drying the obtained sheet at the temperature of 120 ℃ for 1h to obtain the heat-conducting graphite film.
Example 2
S1, crushing the artificial graphite film leftover materials into short-cut graphite fibers, soaking the short-cut graphite fibers in a silane coupling agent K-550, and drying in an anhydrous environment, wherein the silane coupling agent K-550 accounts for 1 wt% of the artificial graphite film leftover materials, so that the hydrophilic short-cut graphite fibers with the length of 6-10 mm are obtained;
s2, mixing 70 parts by mass of hydrophilic chopped graphite fibers, 30 parts by mass of softwood kraft pulp (with a concentration of 3 wt.%) and 5 parts by mass of carboxymethyl cellulose, and stirring the obtained mixture at a rotating speed of 3000rpm for 30min for defibering to obtain mixed slurry;
s3, performing net part papermaking on the mixed pulp, and drying for 1h at 120 ℃ to obtain base paper with the thickness of 1 mm;
s4, spraying a binder polyvinyl alcohol aqueous solution with the mass percentage of 5wt.% on the surface of the obtained base paper, wherein the mass ratio of the binder to the base paper is 3: 100, extruding the base paper with the surface applied with the binder on a double-roller rolling machine to obtain a sheet with the thickness of 0.5mm, and finally drying the obtained sheet at the temperature of 120 ℃ for 1h to obtain the heat-conducting graphite film.
Example 3
S1, crushing the artificial graphite film leftover into chopped graphite fibers, soaking the chopped graphite fibers in a silane coupling agent K-550, and drying in an anhydrous environment, wherein the silane coupling agent K-550 accounts for 1 wt% of the artificial graphite film leftover, so as to obtain the hydrophilic chopped graphite fibers with the length of 6-10 mm;
s2, mixing 80 parts by mass of hydrophilic chopped graphite fibers, 20 parts by mass of softwood kraft pulp (with the concentration of 3 wt.%) and 1 part by mass of carboxymethyl cellulose, and stirring the obtained mixture at the rotating speed of 3000rpm for 30min for defibering to obtain mixed slurry;
s3, performing net part papermaking on the mixed pulp, and drying for 1h at 120 ℃ to obtain base paper with the thickness of 0.5 mm;
s4, spraying a binder polyvinyl alcohol aqueous solution with the mass percentage of 5wt.% on the surface of the obtained base paper, wherein the mass ratio of the binder to the base paper is 3: 100, extruding the base paper with the surface applied with the binder on a double-roller rolling machine to obtain a sheet with the thickness of 0.35mm, and finally drying the obtained sheet at the temperature of 120 ℃ for 1h to obtain the heat-conducting graphite film.
Example 4
S1, crushing the leftover materials of the artificial graphite film into chopped graphite fibers, and performing oxygen plasma modification on the chopped graphite fibers for 60S by using oxygen plasma through a plasma irradiation method to obtain hydrophilic chopped graphite fibers with the lengths of 6-10 mm;
s2, mixing 90 parts by mass of hydrophilic chopped graphite fibers, 10 parts by mass of softwood kraft pulp (with a concentration of 3 wt.%) and 1 part by mass of carboxymethyl cellulose, and stirring the obtained mixture at a rotating speed of 3000rpm for 30min for defibering to obtain mixed slurry;
s3, performing net part papermaking on the mixed pulp, and drying for 1h at 120 ℃ to obtain base paper with the thickness of 0.5 mm;
s4, spraying a binder polyvinyl alcohol aqueous solution with the mass percentage of 5wt.% on the surface of the obtained base paper, wherein the mass ratio of the binder to the base paper is 3: 100, extruding the base paper with the surface applied with the binder on a double-roller rolling machine to obtain a sheet with the thickness of 0.28mm, and finally drying the obtained sheet at the temperature of 120 ℃ for 1h to obtain the heat-conducting graphite film.
Example 5
S1, crushing the leftover materials of the artificial graphite film into chopped graphite fibers, and performing oxygen plasma modification on the chopped graphite fibers for 60S by using oxygen plasma through a plasma irradiation method to obtain hydrophilic chopped graphite fibers with the lengths of 6-10 mm;
s2, mixing 80 parts by mass of hydrophilic chopped graphite fibers, 20 parts by mass of softwood kraft pulp (with the concentration of 3 wt.%) and 1 part by mass of carboxymethyl cellulose, and stirring the obtained mixture at the rotating speed of 3000rpm for 30min for defibering to obtain mixed slurry;
s3, performing net part papermaking on the mixed pulp, and drying for 1h at 120 ℃ to obtain base paper with the thickness of 0.3 mm;
s4, spraying a binder polyvinyl alcohol aqueous solution with the mass percentage of 5wt.% on the surface of the obtained base paper, wherein the mass ratio of the binder to the base paper is 3: 100, extruding the base paper with the surface applied with the binder on a double-roller rolling machine to obtain a sheet with the thickness of 0.1mm, and finally drying the obtained sheet at the temperature of 120 ℃ for 1h to obtain the heat-conducting graphite film.
Example 6
S1, crushing the artificial graphite film leftover into short-cut graphite fibers, soaking the short-cut graphite fibers in concentrated nitric acid for 2 hours, and then cleaning the short-cut graphite fibers to be neutral to obtain hydrophilic short-cut graphite fibers with the length of 6-10 mm;
s2, mixing 90 parts by mass of hydrophilic chopped graphite fibers, 10 parts by mass of softwood kraft pulp (with a concentration of 3 wt.%) and 1 part by mass of carboxymethyl cellulose, and stirring the obtained mixture at a rotating speed of 3000rpm for 30min for defibering to obtain mixed slurry;
s3, performing net part papermaking on the mixed pulp, and drying for 1h at 120 ℃ to obtain base paper with the thickness of 0.6 mm;
s4, spraying a binder polyvinyl alcohol aqueous solution with the mass percentage of 5wt.% on the surface of the obtained base paper, wherein the mass ratio of the binder to the base paper is 3: 100, extruding the base paper with the surface applied with the binder on a double-roller rolling machine to obtain a sheet with the thickness of 0.25mm, and finally drying the obtained sheet at the temperature of 120 ℃ for 1h to obtain the heat-conducting graphite film.
Example 7
S1, crushing the artificial graphite film leftover into short-cut graphite fibers, soaking the short-cut graphite fibers in concentrated nitric acid for 2 hours, and then cleaning the short-cut graphite fibers to be neutral to obtain hydrophilic short-cut graphite fibers with the length of 6-10 mm;
s2, mixing 80 parts by mass of hydrophilic chopped graphite fibers, 20 parts by mass of softwood kraft pulp (with the concentration of 3 wt.%) and 1 part by mass of carboxymethyl cellulose, and stirring the obtained mixture at the rotating speed of 3000rpm for 30min for defibering to obtain mixed slurry;
s3, performing net part papermaking on the mixed pulp, and drying for 1h at 120 ℃ to obtain base paper with the thickness of 0.45 mm;
s4, spraying a binder polyvinyl alcohol aqueous solution with the mass percentage of 5wt.% on the surface of the obtained base paper, wherein the mass ratio of the binder to the base paper is 3: 100, extruding the base paper with the surface applied with the binder on a double-roller rolling machine to obtain a sheet with the thickness of 0.19mm, and finally drying the obtained sheet at the temperature of 120 ℃ for 1h to obtain the heat-conducting graphite film.
The volume density and the thermal conductivity of the heat-conducting graphite film obtained in the embodiment 1-7 are tested according to GB/T22588-2008, and the obtained test results are shown in Table 1.
Figure DEST_PATH_IMAGE002
As shown in Table 1, the volume density of the heat-conducting graphite film obtained by the method provided by the invention reaches 0.51-0.80 g/cm3The thermal conductivity reaches 443-565W/m.K, and the high-density high-thermal conductivity ceramic has high density and good thermal conductivity.
The heat-conducting graphite film prepared by the method provided by the invention is positioned between the artificial graphite film and the natural graphite film in thickness and heat-conducting capacity, so that the blank of the area is filled, and the selection of heat control design is enriched.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (9)

1. A method for preparing a heat-conducting graphite film by utilizing artificial graphite film leftover materials is characterized by comprising the following steps:
s1, sequentially crushing and hydrophilically modifying the artificial graphite film leftover materials to obtain hydrophilic short-cut graphite fibers, wherein the length of each hydrophilic short-cut graphite fiber is 6-10 mm;
s2, uniformly mixing the hydrophilic chopped graphite fibers prepared in the step S1, paper pulp, a dispersing agent and water, and defibering the obtained mixture to obtain mixed slurry; the mass ratio of the total mass of the hydrophilic chopped graphite fibers, the paper pulp and the dispersing agent to water is 1 (1-5), the mass of the hydrophilic chopped graphite fibers accounts for 60-90% of the total mass of the hydrophilic chopped graphite fibers and the paper pulp, and the mass of the dispersing agent accounts for 1-5% of the total mass of the hydrophilic chopped graphite fibers and the paper pulp;
s3, sequentially carrying out wire papermaking and primary drying on the mixed slurry prepared in the step S2 to obtain base paper;
s4, applying a binder on the surface of the base paper prepared in the step S3, wherein the mass ratio of solute in the binder to the base paper is (1-10): 100, laminating the raw paper with the surface applied with the binding agent, and then sequentially extruding and drying for the second time to obtain a heat-conducting graphite film; the direction of the extrusion is perpendicular to the paper surface.
2. The method for preparing the heat-conducting graphite film by using the artificial graphite film leftover material according to claim 1, wherein the method comprises the following steps: in the step S1, the hydrophilic modification is coupling agent modification, oxygen plasma modification, or nitric acid modification.
3. The method for preparing the heat-conducting graphite film by using the artificial graphite film leftover material according to claim 1, wherein the method comprises the following steps: in step S2, the dispersant is carboxymethyl cellulose or carboxyethyl cellulose.
4. The method for preparing the heat-conducting graphite film by using the artificial graphite film leftover material according to claim 1, wherein the method comprises the following steps: in the step S2, the defibering is performed under the condition of stirring, the stirring speed is 1000-5000 rpm, and the stirring time is 1-30 min.
5. The method for preparing the heat-conducting graphite film by using the artificial graphite film leftover material according to claim 1, wherein the method comprises the following steps: in the step S3, the thickness of the prepared base paper is 0.3-1.5 mm.
6. The method for preparing the heat-conducting graphite film by using the artificial graphite film leftover material according to claim 1, wherein the method comprises the following steps: in the step S4, the binder is a polyvinyl alcohol aqueous solution, and the mass percentage of the polyvinyl alcohol aqueous solution is 3 to 10 wt.%.
7. The method for preparing the heat-conducting graphite film by using the artificial graphite film leftover material according to claim 1, wherein the method comprises the following steps: in the step S4, the deformation of the extruded base paper is 33-70%.
8. The method for preparing the heat-conducting graphite film by using the artificial graphite film leftover material according to claim 1, wherein the method comprises the following steps: the drying temperature of the primary drying in the step S3 and the drying temperature of the secondary drying in the step S4 are both 80-130 ℃, and the drying time is both 10-100 min.
9. The method for preparing the heat-conducting graphite film by using the artificial graphite film leftover material according to claim 1, wherein the method comprises the following steps: the thickness of the heat-conducting graphite film prepared in the step S4 is 0.1-1 mm, and the volume density is 0.3-0.8 g/cm3The thermal conductivity is 400 to 600W/m.K.
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CN109911893A (en) * 2018-12-04 2019-06-21 重庆云天化瀚恩新材料开发有限公司 The preparation method of thermally conductive electrographite gasket
CN111017920A (en) * 2019-12-02 2020-04-17 广东工业大学 High-thermal-conductivity graphite film and preparation method and application thereof
CN111212555A (en) * 2020-03-03 2020-05-29 世星科技股份有限公司 Super-thick heat-conducting graphite film and preparation method thereof

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JPH0219598A (en) * 1988-07-07 1990-01-23 Nippon Kasei Kk Flame retardant composite paper material and production thereof
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TW201817676A (en) * 2016-11-10 2018-05-16 達邁科技股份有限公司 Polyimide film for graphitization process, graphite film and a method of manufacturing the same characterized by adding a foaming agent in a graphitization process to increase the foaming thickness of the polyimide film, and the graphitization parameters can be fixed to allow the selection of different graphite film thicknesses freely
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