CN112456484B - Graphite heat-conducting film and preparation method thereof - Google Patents
Graphite heat-conducting film and preparation method thereof Download PDFInfo
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Abstract
A method for preparing a graphite heat-conducting film, comprising the steps of: preparing dispersion liquid, adding the multi-walled carbon nano-tubes subjected to surface treatment into a solvent for mixing, and performing ultrasonic dispersion to form uniform carbon nano-tube dispersion liquid; preparing polyamic acid resin, namely adding a diamine monomer, a dianhydride monomer and an inorganic filler into the carbon nano tube dispersion liquid in sequence, and performing polycondensation reaction to generate the polyamic acid resin; preparing a polyamic acid adhesive film, carrying out tape casting on polyamic acid resin, and carrying out partial imidization to obtain the polyamic acid adhesive film; preparing a polyimide composite film, heating a polyamic acid adhesive film at a high temperature, and stretching the polyamic acid adhesive film in a transverse direction and a longitudinal direction to obtain the polyimide composite film; preparing a graphite heat-conducting film, and sequentially carrying out carbonization and graphitization treatment on the polyimide composite film to obtain the graphite heat-conducting film. The graphite heat-conducting film has good mechanical and heat-conducting properties, and the preparation method of the graphite heat-conducting film is simple in process.
Description
Technical Field
The invention relates to the field of high polymer materials, in particular to a graphite heat-conducting film and a preparation method thereof.
Background
The traditional heat dissipation materials are metals with high heat conductivity, such as copper, silver and aluminum, but the requirements of microelectronic products cannot be met with the increase of the heat productivity of electronic components. The graphite film has higher thermal conductivity and good material stability, and has wide application prospect in the fields of microelectronic packaging and integration.
In the last 70 th century, scientists found that Polyimide (PI) films could be carbonized and graphitized to obtain highly oriented graphite heat-conducting films close to single-crystal graphite structures. However, the graphite film prepared from the conventional PI film has low thermal conductivity, poor mechanical property and low bending resistance, and is easy to fall off and break in the preparation and use processes. With the expansion of 5G communications, the need for thermal management materials with superior performance is also increasing.
Disclosure of Invention
In view of the above, there is a need for a method for preparing a graphite heat-conducting film, which is simple and has excellent mechanical properties and heat-conducting properties.
The graphite heat-conducting film is obtained by carbonizing, graphitizing and rolling a polyimide film, the thickness of the graphite heat-conducting film is 15-50 micrometers, the tensile strength of the graphite heat-conducting film is larger than 60MPa, and the heat conductivity of the graphite heat-conducting film is larger than 1600W/(m.K).
A method for preparing a graphite heat-conducting film, comprising the steps of:
(1) preparing dispersion liquid, adding the multi-walled carbon nanotubes with different lengths subjected to acidizing or amination surface treatment into a solvent for mixing, and performing ultrasonic dispersion to form uniform carbon nanotube dispersion liquid;
(2) preparing polyamic acid resin, namely adding a diamine monomer, a dianhydride monomer and an inorganic filler into the carbon nano tube dispersion liquid in sequence, and performing polycondensation reaction to generate the polyamic acid resin;
(3) preparing a polyamic acid adhesive film, carrying out tape casting on the polyimide resin, and carrying out partial imidization to obtain the polyamic acid adhesive film;
(4) preparing a polyimide composite film, heating a polyamic acid adhesive film at high temperature and stretching the polyamic acid adhesive film in a transverse direction and a longitudinal direction to obtain the polyimide composite film;
(5) preparing a graphite heat-conducting film, and sequentially carrying out carbonization, graphitization and calendering treatment on the polyimide composite film to obtain the graphite heat-conducting film.
In a preferred technical scheme of the invention, the solvent in the step (1) is one or more of N, N '-dimethylformamide, N' -dimethylacetamide and N-methylpyrrolidone.
In a preferable technical scheme of the invention, the diameter of the multi-walled carbon nanotube in the step (1) is 20-100 nm, the lengths of the two specifications are respectively (a) 0.5-0.8 μm and (b) 2-5 μm, the mass ratio of a to b is 80: 20-60: 40, and the total addition amount of the carbon nanotubes is 0.1-2% of the total mass of the polyimide composite film.
In a preferred technical scheme of the present invention, the diamine monomer in step (2) is one or a combination of more of p-phenylenediamine, 4 '-diaminodiphenyl ether, 4' -diaminodiphenyl sulfone, 4 '-diaminobenzophenone, and 3,4' -diaminodiphenyl ether.
In a preferred technical scheme of the present invention, the dianhydride monomer in step (2) is one or a combination of more of pyromellitic dianhydride, 3,3',4,4' -biphenyl tetracarboxylic dianhydride, 2,3,3',4' -diphenyl ether tetracarboxylic dianhydride, and 3,3',4,4' -benzophenone tetracarboxylic dianhydride.
In a preferred embodiment of the present invention, the inorganic filler in step (2) includes one or more of inorganic salts, oxides, nitrides and carbides, and is preferably calcium hydrogen phosphate.
In a preferable technical scheme of the invention, the particle size of the inorganic filler in the step (2) is 50-2000 nm, preferably 500 nm.
In a preferable technical scheme of the present invention, in the step (2), the solid content of the diamine monomer, the dianhydride monomer and the inorganic filler added to the carbon nanotube dispersion liquid is set to 10-35%.
In the preferable technical scheme of the invention, the inorganic filler in the step (2) accounts for 0.05-5% of the total weight of the polyimide composite film.
In a preferred technical scheme of the invention, the molar ratio of the diamine monomer to the dianhydride monomer in the step (2) is 1: (0.8 to 1.2), preferably 1: 1.
In the preferable technical scheme of the invention, the diamine monomer in the step (2) is 4,4' -diaminodiphenyl ether, the dianhydride monomer is pyromellitic dianhydride, the molar ratio of the diamine monomer to the dianhydride monomer is 1:1, and the inorganic filler is calcium hydrophosphate.
In a preferred embodiment of the present invention, the viscosity of the polyamic acid resin in the step (2) is controlled to be 10 to 45 × 104mPa·s。
In a preferred embodiment of the present invention, the imidization method in the step (3) includes one of a thermal imidization method for dehydrating the polyamic acid by heating to form the polyimide and a chemical imidization method for adding a catalyst and a dehydrating agent to the polyamic acid to convert the polyamic acid into the polyimide.
In the preferable technical scheme of the invention, in the step (5), the polyimide composite film is sequentially put into a carbonization furnace and a graphitization furnace for carbonization and graphitization treatment, and is taken out for calendaring and cutting to obtain the graphite heat-conducting film.
A method for preparing a graphite heat-conducting film, comprising the steps of:
preparing dispersion liquid, adding the acidified multi-walled carbon nano-tubes into a solvent for mixing, and performing ultrasonic dispersion to form uniform carbon nano-tube dispersion liquid;
preparing polyamic acid resin, namely adding a diamine monomer, a dianhydride monomer and an inorganic filler into the carbon nano tube dispersion liquid in sequence, and performing polycondensation reaction to generate the polyamic acid resin;
preparing a polyamic acid adhesive film, carrying out tape casting on the polyimide resin, and carrying out partial imidization to obtain the polyamic acid adhesive film;
preparing a polyimide composite film, heating a polyamic acid adhesive film at high temperature and stretching the polyamic acid adhesive film in a transverse direction and a longitudinal direction to obtain the polyimide composite film;
preparing a graphite heat-conducting film, and sequentially carrying out carbonization and graphitization treatment on the polyimide composite film to obtain the graphite heat-conducting film.
Further, the solvent in the step of preparing the dispersion liquid is one or more of N, N '-dimethylformamide, N' -dimethylacetamide and N-methylpyrrolidone.
Furthermore, the diameter of the multi-walled carbon nanotube in the step of preparing the dispersion liquid is 20-100 nm, the length of the multi-walled carbon nanotube is 0.5-5 microns, the addition amount of the multi-walled carbon nanotube is 0.1-2% of the total mass of the polyimide composite film, the tensile strength of the multi-walled carbon nanotube is more than 50GPa, and the thermal conductivity of the multi-walled carbon nanotube is more than 2500W/(m.K).
Further, the imidization method in the step of preparing the polyimide composite film includes a thermal imidization method and a chemical imidization method.
Further, the diamine monomer in the step of preparing the polyamic acid resin is one or more of p-phenylenediamine, 4 '-diaminodiphenyl ether, 4' -diaminodiphenyl sulfone, 4 '-diaminobenzophenone and 3,4' -diaminodiphenyl ether.
Further, the dianhydride monomer in the step of preparing the polyamic acid resin is one or more of pyromellitic dianhydride, 3,3',4,4' -biphenyl tetracarboxylic dianhydride, 2,3,3',4' -diphenyl ether tetracarboxylic dianhydride and 3,3',4,4' -benzophenone tetracarboxylic dianhydride.
Further, the inorganic filler in the step of preparing the polyamic acid resin includes one or more of inorganic salt, oxide, nitride, and carbide.
Further, in the step of preparing the polyamic acid resin, the solid content of the diamine monomer, the dianhydride monomer and the inorganic filler added to the carbon nanotube dispersion liquid is set to 10-35%.
Further, the viscosity of the polyamic acid resin in the preparation of the polyamic acid resin is controlled to be 10-45 multiplied by 104mPa·s。
The graphite heat-conducting film prepared by the method has the tensile strength of more than 60MPa and the heat conductivity of more than 1600W/(m.K).
Unless otherwise specified, the performance parameters in the present invention are determined as follows:
mechanical properties: the test standard was ASTM D882 using an INSTRON-6800 Universal testing machine.
Thermal conductivity: NETZSCH-LFA467 laser thermal conductivity instrument is used, room temperature, In-Plane mode, 14mm of light spot and nitrogen protection.
And (3) bending resistance test: and (3) using an INUO-YN-MIT135 type folding endurance tester with the test standard of IPCTM650, and observing whether the surface of the graphite film has folds after bending for 3000 times.
The invention has the beneficial effects that:
the carbon nano tubes with different sizes are used for constructing the three-dimensional network structure, so that the prepared graphite film has good mechanical and heat-conducting properties, the comprehensive performance of the sintered graphite film is greatly improved, the sintered graphite film has higher heat conductivity, better tensile strength and folding resistance, the powder falling phenomenon in the firing process is inhibited, the preparation process of the graphite heat-conducting film is simple, and the practicability is high.
Drawings
Fig. 1 is a schematic flow chart of a method for preparing a graphite heat-conducting film according to an embodiment of the present invention.
The following detailed description will further illustrate the invention in conjunction with the above-described figures.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. 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.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "or/and" includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1, fig. 1 is a schematic flow chart of a method for preparing a graphite heat conduction film according to an embodiment of the present invention, which specifically includes the following steps:
s11, adding the acidified multi-walled carbon nanotubes into a solvent, mixing, and performing ultrasonic dispersion to form a uniform carbon nanotube dispersion liquid;
s12, sequentially adding a diamine monomer, a dianhydride monomer and an inorganic filler into the carbon nanotube dispersion liquid, and carrying out polycondensation reaction to generate polyamide acid resin;
s13, casting the polyamic acid resin, and obtaining a polyamic acid adhesive film after partial imidization;
s14, heating the polyamic acid adhesive film at high temperature and performing transverse and longitudinal biaxial stretching to obtain a polyimide composite film;
and S15, sequentially carbonizing and graphitizing the polyimide composite film to obtain the graphite heat-conducting film.
In one embodiment, the solvent in step S11 comprises one or more of N, N '-dimethylformamide, N' -dimethylacetamide, and N-methylpyrrolidone.
In one embodiment, the diameter of the multi-walled carbon nanotube in the step S11 is 20 to 100nm, the length is 0.5 to 5 μm, the addition amount is 0.01 to 5% of the total mass of the polyimide composite film, preferably 0.1 to 2%, the tensile strength of the multi-walled carbon nanotube is greater than 50GPa, the thermal conductivity is greater than 2500W/(m · K), and the mechanical and thermal conductivity of the graphite thermal conductive film obtained by sintering can be greatly improved. The surface of the treated multi-wall carbon nano tube contains functional groups such as carboxyl, hydroxyl, amino and the like, the dispersibility of the multi-wall carbon nano tube in an organic solvent is improved through ultrasonic dispersion treatment, the resin viscosity is increased along with the addition of diamine and dianhydride monomers in a system, and the dispersed carbon nano tube is separated by macromolecular chains, so that the re-agglomeration of the multi-wall carbon nano tube in a polyimide film is prevented.
In one embodiment, the diamine monomer in step S12 is one or more of p-phenylenediamine, 4 '-diaminodiphenyl ether, 4' -diaminodiphenyl sulfone, 4 '-diaminobenzophenone, and 3,4' -diaminodiphenyl ether.
In one embodiment, the dianhydride monomer in step S12 is one or more of pyromellitic dianhydride, 3,3',4,4' -biphenyl tetracarboxylic dianhydride, 2,3,3',4' -diphenyl ether tetracarboxylic dianhydride, and 3,3',4,4' -benzophenone tetracarboxylic dianhydride.
The inorganic filler in step S12 includes one or more of inorganic salt, oxide, nitride and carbide. The inorganic filler has a particle size of 50-2000 nm, and accounts for 0.05-5% of the total weight of the polyimide composite film, and in one embodiment, the inorganic filler is calcium hydrogen phosphate, and the particle size is 500 nm. The inorganic filler is used as a slipping agent, so that the surface of the prepared polyimide film is smoother and is not adhered.
In one embodiment, the solid content of the diamine monomer, the dianhydride monomer, and the inorganic filler sequentially added to the carbon nanotube dispersion in step S12 is set to 10 to 35%. The molar ratio of diamine monomer to dianhydride monomer is about 1: 1.
In one embodiment, the viscosity of the polyamic acid resin in the step S12 is controlled to be 10-45 × 104mPa·s。
In one embodiment, the imidization method in steps S13 and S14 includes a thermal imidization method in which the polyamic acid is dehydrated by heating to form polyimide, and a chemical imidization method in which a catalyst and a dehydrating agent are added to the polyamic acid to convert the polyamic acid into polyimide.
And S15, specifically, putting the polyimide composite film into a carbonization furnace and a graphitization furnace in sequence for carbonization and graphitization treatment, taking out, and rolling and cutting to obtain the graphite heat-conducting film.
The graphite heat-conducting film prepared by the method has the tensile strength of more than 60MPa and the heat conductivity of more than 1600W/(m.K).
The present invention will be further described with reference to specific examples. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
Example 1
Taking 1.25g of acidified multi-walled carbon nano-tube with the diameter of 80nm and the length of 2 mu m, adding 2.1kg of N, N-dimethylformamide for mixing, performing ultrasonic dispersion for 1h to obtain uniform and stable carbon nano-tube dispersion, adding 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 2.1g of calcium hydrophosphate filler into the carbon nano-tube dispersion, performing polycondensation reaction for 2h to obtain polyamic acid resin, performing vacuum defoamation, adding a chemical imidization reagent, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, casting to obtain a polyamic acid adhesive film, performing high-temperature heating and bidirectional stretching to obtain a polyimide composite film, sequentially putting the polyimide composite film into a carbonization furnace and a graphitization furnace for carbonization and graphitization, and taking out, rolling and cutting to obtain the graphite heat-conducting film.
Example 2
Taking 4.18g of acidified multi-walled carbon nano-tube with the diameter of 80nm and the length of 2 mu m, adding 2.1kg of N, N-dimethylformamide for mixing, performing ultrasonic dispersion for 1h to obtain uniform and stable carbon nano-tube dispersion, adding 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 2.1g of calcium hydrophosphate filler into the carbon nano-tube dispersion, performing polycondensation reaction for 2h to obtain polyamic acid resin, performing vacuum defoaming, adding chemical imidization reagents, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, casting to obtain a polyamic acid adhesive film, performing high-temperature heating and bidirectional stretching to obtain a polyimide composite film, sequentially putting the polyimide composite film into a carbonization furnace and a graphitization furnace for carbonization and graphitization, and taking out, rolling and cutting to obtain the graphite heat-conducting film.
Example 3
Taking 6.72g of acidified multi-walled carbon nano-tube with the diameter of 80nm and the length of 2 μm, adding 2.1kg of N, N-dimethylformamide for mixing, performing ultrasonic dispersion for 1h to obtain uniform and stable carbon nano-tube dispersion, adding 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 2.1g of calcium hydrophosphate filler into the carbon nano-tube dispersion, performing polycondensation reaction for 2h to obtain polyamic acid resin, performing vacuum defoamation, adding chemical imidization reagents, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, casting to obtain a polyamic acid adhesive film, performing high-temperature heating and bidirectional stretching to obtain a polyimide composite film, sequentially putting the polyimide composite film into a carbonization furnace and a graphitization furnace for carbonization and graphitization, and taking out, rolling and cutting to obtain the graphite heat-conducting film.
Example 4
Taking 7.5g of acidified multi-walled carbon nano-tube with the diameter of 80nm and the length of 2 mu m, adding 2.1kg of N, N-dimethylformamide for mixing, performing ultrasonic dispersion for 1h to obtain uniform and stable carbon nano-tube dispersion, adding 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 2.1g of calcium hydrophosphate filler into the carbon nano-tube dispersion, performing polycondensation reaction for 2h to obtain polyamic acid resin, performing vacuum defoamation, adding chemical imidization reagents, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, casting to obtain a polyamic acid adhesive film, performing high-temperature heating and bidirectional stretching to obtain a polyimide composite film, sequentially putting the polyimide composite film into a carbonization furnace and a graphitization furnace for carbonization and graphitization, and taking out, rolling and cutting to obtain the graphite heat-conducting film.
Comparative example 1
Carrying out polycondensation reaction on 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 2.1g of calcium hydrogen phosphate filler for 2h to obtain polyamic acid resin, adding a chemical imidization reagent, specifically 204.2g of acetic anhydride and 25.8g of isoquinoline, casting to obtain a polyamic acid adhesive film, heating at high temperature and carrying out biaxial stretching to obtain a polyimide composite film, sequentially putting the polyimide composite film into a carbonization furnace and a graphitization furnace for carbonization and graphitization treatment, taking out, and carrying out calendaring and cutting to obtain the graphite heat-conducting film.
Comparative example 2
Taking 0.2g of acidified multi-walled carbon nano-tube with the diameter of 80nm and the length of 2 mu m, adding 2.1kg of N, N-dimethylformamide for mixing, performing ultrasonic dispersion for 1h to obtain uniform and stable carbon nano-tube dispersion, adding 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 2.1g of calcium hydrophosphate filler into the carbon nano-tube dispersion, performing polycondensation reaction for 2h to obtain polyamic acid resin, performing vacuum defoaming, adding chemical imidization reagents, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, casting to obtain a polyamic acid adhesive film, performing high-temperature heating and bidirectional stretching to obtain a polyimide composite film, sequentially putting the polyimide composite film into a carbonization furnace and a graphitization furnace for carbonization and graphitization, and taking out, rolling and cutting to obtain the graphite heat-conducting film.
Comparative example 3
Taking 9.2g of acidified multi-walled carbon nano-tube with the diameter of 80nm and the length of 2 mu m, adding 2.1kg of N, N-dimethylformamide for mixing, performing ultrasonic dispersion for 1h to obtain uniform and stable carbon nano-tube dispersion, adding 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 2.1g of calcium hydrophosphate filler into the carbon nano-tube dispersion, performing polycondensation reaction for 2h to obtain polyamic acid resin, performing vacuum defoaming, adding chemical imidization reagents, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, casting to obtain a polyamic acid adhesive film, performing high-temperature heating and bidirectional stretching to obtain a polyimide composite film, sequentially putting the polyimide composite film into a carbonization furnace and a graphitization furnace for carbonization and graphitization, and taking out, rolling and cutting to obtain the graphite heat-conducting film.
As can be seen from table 1, after the multi-walled carbon nanotubes are added, the carbon nanotubes form a three-dimensional network in the graphite heat-conducting film obtained by sintering, so that the heat conductivity of the graphite heat-conducting film is increased, the tensile strength and the bending resistance are improved, the phenomenon of powder falling due to crushing in the sintering process is suppressed, but after the addition amount exceeds 2%, the dispersibility of the carbon nanotubes is reduced, the agglomeration is generated, various properties are reduced, and the powder falling phenomenon occurs.
Table 1 shows the appearance, mechanical properties and thermal conductivity test data of the products of comparative example and example.
As can be seen from table 1, the tensile strength of the graphite heat conductive film obtained by sintering after adding the multi-walled carbon nanotubes was increased, but when the addition amount exceeded 2%, the tensile strength was rather decreased due to the poor dispersibility of the carbon nanotubes, and at the same time, the graphite heat conductive film became brittle and was prone to powder falling due to the excessively high addition amount of the carbon nanotubes. The addition of proper amount of multi-wall carbon nano-tubes can greatly improve the thermal conductivity of the graphite film obtained by sintering, so that the tensile strength of the graphite heat-conducting film is more than 60MPa, and the thermal conductivity is more than 1600W/(m.K).
The graphite heat-conducting film and the preparation method utilize the good heat conductivity of the carbon nano tube, the carbon nano tube can form a heat-conducting network in the polyimide film after being doped with the polyimide film, the heat conductivity of the graphite film obtained by sintering is greatly improved, the preparation process of the graphite heat-conducting film is simple, the graphite heat-conducting film is suitable for various polyimide films, even in the simplest single dianhydride and diamine resin system, the prepared graphite heat-conducting film has excellent performance, the heat conductivity is more than 1600W/(m.K), and the graphite heat-conducting film has excellent mechanical performance, wherein the tensile strength is more than 60MPa, and the whole production process is simple and easy to implement and is beneficial to popularization.
Example 5
Taking 2.1g of multi-walled carbon nanotubes subjected to surface treatment, wherein the diameter of the multi-walled carbon nanotubes is 80nm, 1.68g of carbon nanotubes with the length of 0.5 mu m and 0.42g of carbon nanotubes with the length of 4 mu m are added into 2.1kg of N, N-dimethylformamide for mixing, obtaining uniform and stable carbon nanotube dispersion after ultrasonic dispersion for 1h, adding 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 2.1g of calcium hydrophosphate filler into the carbon nanotube dispersion, wherein the particle size of the calcium hydrophosphate is 500nm, carrying out polycondensation reaction for 2h to obtain resin, adding a chemical imidization reagent after vacuum defoamation, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, carrying out tape casting to obtain a polyamide acid adhesive film, carrying out high-temperature heating and carrying out biaxial stretching to obtain a polyimide composite film, sequentially putting the polyimide composite film into a carbonization furnace and a graphitization furnace for carbonization and graphitization treatment, and taking out, rolling and cutting to obtain the graphite heat-conducting film.
Example 6
The procedure was the same as in example 5, except that the total amount of the multi-walled carbon nanotubes added was 3.39g, the diameter was 80nm, 2.373g of carbon nanotubes having a length of 0.5 μm and 1.017g of carbon nanotubes having a length of 4 μm.
Example 7
The procedure was the same as in example 5, except that the total amount of the multi-walled carbon nanotubes added was 5.73g, the diameter was 80nm, 4.011g of carbon nanotubes having a length of 0.5 μm and 1.719g of carbon nanotubes having a length of 4 μm.
Example 8
The procedure was the same as in example 5, except that the total amount of the multi-walled carbon nanotubes added was 8.01g, the diameter was 80nm, 4.806g of carbon nanotubes having a length of 0.5 μm and 3.204g of carbon nanotubes having a length of 4 μm.
Comparative example 4
The procedure was the same as in example 5, except that the total amount of the multi-walled carbon nanotubes added was 0.336g, the diameter was 80nm, and 0.147g of carbon nanotubes having a length of 0.5 μm and 0.063g of carbon nanotubes having a length of 4 μm were used.
Comparative example 5
The procedure was the same as in example 5, except that the total amount of the multi-walled carbon nanotubes added was 9.02g, the diameter was 80nm, 6.314g of carbon nanotubes having a length of 0.5 μm and 2.706g of carbon nanotubes having a length of 4 μm.
Comparative example 6
The procedure was the same as in example 5, except that the total amount of the multi-walled carbon nanotubes added was 5.73g, the diameter was 80nm, 2.865g of carbon nanotubes having a length of 0.5 μm and 2.865g of carbon nanotubes having a length of 4 μm.
Comparative example 7
The procedure was the same as in example 5, except that the total amount of the multi-walled carbon nanotubes added was 5.73g, the diameter was 80nm, 5.157g of carbon nanotubes having a length of 0.5 μm and 0.573g of carbon nanotubes having a length of 4 μm.
Table 2 shows the appearance, mechanical properties and thermal conductivity test data of the products of comparative example and example.
It should be understood by those skilled in the art that the above embodiments are only for illustrating the present invention and are not to be used as a limitation of the present invention, and that suitable changes and modifications of the above embodiments are within the scope of the claimed invention as long as they are within the spirit and scope of the present invention.
Claims (17)
1. The preparation method of the graphite heat-conducting film is characterized in that the graphite heat-conducting film is obtained by carbonizing, graphitizing and rolling a polyimide film, the thickness of the graphite heat-conducting film is 15-50 mu m, the tensile strength of the graphite heat-conducting film is more than 60MPa, and the heat conductivity is more than 1600W/(m.K);
the preparation method of the graphite heat conduction film comprises the following steps:
(1) preparing dispersion liquid, adding the multi-walled carbon nanotubes with different lengths subjected to acidizing or amination surface treatment into a solvent for mixing, and performing ultrasonic dispersion to form uniform carbon nanotube dispersion liquid;
(2) preparing polyamic acid resin, namely adding a diamine monomer, a dianhydride monomer and an inorganic filler into the carbon nano tube dispersion liquid in sequence, and performing polycondensation reaction to generate the polyamic acid resin;
(3) preparing a polyamic acid adhesive film, carrying out tape casting on the polyimide resin, and carrying out partial imidization to obtain the polyamic acid adhesive film;
(4) preparing a polyimide composite film, heating a polyamic acid adhesive film at high temperature and stretching the polyamic acid adhesive film in a transverse direction and a longitudinal direction to obtain the polyimide composite film;
(5) preparing a graphite heat-conducting film, and sequentially carrying out carbonization, graphitization and calendering treatment on the polyimide composite film to obtain the graphite heat-conducting film;
the diameter of the multi-walled carbon nanotube in the step (1) is 20-100 nm, the lengths of the two specifications are respectively (a) 0.5-0.8 mu m and (b) 2-5 mu m, the mass ratio of a to b is 80: 20-60: 40, and the total addition amount of the carbon nanotube is 0.1-2% of the total mass of the polyimide composite film.
2. The method of claim 1, wherein the solvent in step (1) is comprised of one or more of N, N '-dimethylformamide, N' -dimethylacetamide, and N-methylpyrrolidone.
3. The method of claim 1, wherein the diamine monomer in step (2) is one or more of p-phenylenediamine, 4 '-diaminodiphenyl ether, 4' -diaminodiphenyl sulfone, 4 '-diaminobenzophenone, and 3,4' -diaminodiphenyl ether.
4. The method according to claim 1, wherein the dianhydride monomer in step (2) is one or more of pyromellitic dianhydride, 3,3',4,4' -biphenyl tetracarboxylic dianhydride, 2,3,3',4' -diphenyl ether tetracarboxylic dianhydride, and 3,3',4,4' -benzophenone tetracarboxylic dianhydride.
5. The method of claim 1, wherein the inorganic filler in step (2) comprises one or more of inorganic salts, oxides, nitrides and carbides, preferably calcium hydrogen phosphate.
6. The method of claim 5, wherein the inorganic filler in step (2) is dibasic calcium phosphate.
7. The method according to claim 1, wherein the inorganic filler in the step (2) has a particle size of 50 to 2000 nm.
8. The method according to claim 7, wherein the inorganic filler in the step (2) has a particle size of 500 nm.
9. The method of claim 1, wherein the solid content of the diamine monomer, the dianhydride monomer and the inorganic filler added to the carbon nanotube dispersion liquid in the step (2) is set to 10 to 35%.
10. The method according to claim 1, wherein the inorganic filler in the step (2) is 0.05 to 5% by weight based on the total weight of the polyimide composite film.
11. The method of claim 1, wherein the molar ratio of diamine monomer to dianhydride monomer in step (2) is 1: (0.8 to 1.2).
12. The method of claim 11, wherein the diamine monomer and dianhydride monomer in step (2) are present in a 1:1 molar ratio.
13. The method of claim 1, wherein the diamine monomer in step (2) is 4,4' -diaminodiphenyl ether, the dianhydride monomer is pyromellitic dianhydride, the molar ratio of the diamine monomer to the dianhydride monomer is 1:1, and the inorganic filler is calcium hydrogen phosphate.
14. The method of claim 1, wherein the viscosity of the polyamic acid resin in the step (2) is controlled to be 10 to 45 x 104mPa·s。
15. The method according to claim 1, wherein the imidization method in the step (3) includes any one of a thermal imidization method of dehydrating the polyamic acid by heating to produce the polyimide and a chemical imidization method of adding a catalyst and a dehydrating agent to the polyamic acid to convert it into the polyimide.
16. The method according to claim 1, wherein in the step (5), the polyimide composite film is sequentially put into a carbonization furnace and a graphitization furnace for carbonization and graphitization treatment, taken out, and then rolled and cut to obtain the graphite heat-conducting film.
17. A graphite heat transfer film prepared by the method of any one of claims 1-16.
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| CN112919452A (en) * | 2021-03-23 | 2021-06-08 | 苏州烯时代材料科技有限公司 | High-heat-flux graphene-polyimide carbonized film and preparation method and application thereof |
| CN113717524A (en) * | 2021-08-31 | 2021-11-30 | 安徽国风塑业股份有限公司 | Polyimide film for preparing graphite film and preparation method thereof |
| CN114736019B (en) * | 2022-06-10 | 2022-09-13 | 宁波长阳科技股份有限公司 | Artificial graphite sheet with high vertical heat conduction and radiating fin comprising artificial graphite sheet |
| CN114956068B (en) * | 2022-06-23 | 2023-09-08 | 中天电子材料有限公司 | Artificial graphite heat conducting film and preparation method thereof |
| CN115353392A (en) * | 2022-07-07 | 2022-11-18 | 慧迈材料科技(广东)有限公司 | Preparation method of polyimide-based graphite film with high thermal conductivity |
| CN116283293B (en) * | 2022-09-07 | 2024-04-30 | 安徽国风新材料股份有限公司 | High-heat-conductivity graphite film and preparation method thereof |
| CN115627073A (en) * | 2022-10-31 | 2023-01-20 | 安徽碳华新材料科技有限公司 | Wide artificial graphite high-conductivity film structure for communication base station |
| CN116731364A (en) * | 2023-07-20 | 2023-09-12 | 广东双拉智造科技有限公司 | Preparation method of polyimide film |
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