WO2019205237A1 - 一种石墨膜的制备方法及其产品和用途 - Google Patents

一种石墨膜的制备方法及其产品和用途 Download PDF

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WO2019205237A1
WO2019205237A1 PCT/CN2018/090732 CN2018090732W WO2019205237A1 WO 2019205237 A1 WO2019205237 A1 WO 2019205237A1 CN 2018090732 W CN2018090732 W CN 2018090732W WO 2019205237 A1 WO2019205237 A1 WO 2019205237A1
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temperature
film
graphite film
rate
graphite
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PCT/CN2018/090732
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English (en)
French (fr)
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赖优萍
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苏州格优碳素新材料有限公司
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Publication of WO2019205237A1 publication Critical patent/WO2019205237A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/20—Graphite
    • C01B32/205—Preparation

Definitions

  • the present application relates to the field of thermal conductive materials, and in particular to a method for preparing a graphite film, a product thereof and a use thereof.
  • Highly oriented graphite has good thermal conductivity due to its highly directional layered structure, and it has shown its irreplaceable superior performance in many fields.
  • the original highly oriented graphite was synthesized by pyrolysis and was called highly oriented pyrolytic graphite, which was obtained by high temperature heat treatment of pyrolytic carbon under stress.
  • highly oriented pyrolytic graphite which was obtained by high temperature heat treatment of pyrolytic carbon under stress.
  • the preparation process of pyrolytic graphite is complicated, which makes the material very expensive and greatly limits its application.
  • PI polyimide
  • the sample prepared has high oriented pyrolytic graphite.
  • CN103011141A discloses a method for manufacturing a high thermal conductivity graphite film, which uses a PI film as a raw material, cuts a PI film and a graphite paper into a fixed size, and laminates a PI film layer cut into a predetermined size into a certain height, and gathers at each layer.
  • Graphite paper is added between the yttrium imide films: the PI film is placed in a carbonization furnace after the graphite paper is cross-laminated, and the carbonization and graphite are performed under the protection of an inert gas at 1000-1400 ° C and 2500-3000 ° C, respectively.
  • a high thermal conductivity graphite film is obtained.
  • the anti-bending property of the graphite film is enhanced, and the brittleness of the graphite film is lowered, but the carbonization degree, the breaking strength, the electrical conductivity and the thermal conductivity of the graphite film are not improved.
  • CN107311661A discloses a preparation method of composite graphite film, comprising: preparing a composite film formed by nano diamond and PI; performing carbonization and graphitization under inert gas protection, and then removing graphite paper to obtain formation by nano diamond and PI.
  • Composite graphite film In the process of carbonization and graphitization, nano-diamond acts as a nucleus to promote the carbonization and graphitization of PI, improve the degree of graphitization and carbonization yield, thereby improving the thermal conductivity and electrical conductivity of the composite carbon film.
  • the thermal conductivity is only 1056W/(m ⁇ K), which needs to be improved, and the degree of dispersion of nano-diamonds will make the crystal structure uniformity of graphite difficult to control, the performance stability of the product is not good enough, and the diamond increases the cost and is not suitable for scale-up production.
  • One of the purposes of the present application is to provide a method for preparing a graphite film, which further improves the thermal conductivity of the graphite film, has high controllability and good repeatability, and is suitable for mass production of high thermal conductivity graphite films of various thicknesses.
  • the embodiment of the present invention adopts the following technical solutions:
  • an embodiment of the present invention provides a method for preparing a graphite film, comprising the following steps:
  • the PI film is heated to 650-750 ° C, constant temperature for 100-150 min, and the temperature is further increased to 850 ° C to 950 ° C, constant temperature for 100-150 min, and the temperature is further increased to 1250 - 1350 ° C, the temperature is 80-130 min, and cooled to obtain a carbonized film;
  • the carbonized film is heated to 1550 ⁇ 1650 ° C, constant temperature 20 ⁇ 60min, continue to raise the temperature to 1750 ⁇ 1850 ° C, constant temperature 20 ⁇ 90min, continue to raise the temperature to 2300 ⁇ 2400 ° C, constant temperature 20 ⁇ 90min, temperature rise 2750 ⁇ 2900 ° C, cooling , a graphite film is obtained.
  • the carbonization stage of the PI film is mainly pyrolysis, releasing CO and CO 2 , and the hetero atoms such as N and O are gradually released, and the molecular chain structure of PI is broken and recombined, and the raw material film is gradually transformed into a crystal structure.
  • the mechanical and thermal conduction and electrical conduction properties are unpredictable.
  • a carbonization gradient heating program is designed to form an appropriate dynamic temperature field, and three constant temperature platforms release a hetero atom in the carbonization process. It is properly buffered to prevent the removal of C atoms from the exclusion of heterocyclic atoms and to reduce defects such as intramolecular cleavage.
  • the impurity removal rate in the carbonization stage is increased while reducing defects such as intramolecular wrinkles or fractures, and a carbonized structure having high crystallinity is obtained.
  • the graphitization stage is much higher than the carbonization stage, and the carbon hexagonal network is mainly ordered, and complex three-phase transformation and carbon recrystallization process occur in the reaction field. At this stage, heterocyclic atoms are further excluded. As the temperature increases, the crystals of C atoms are more rapidly and violently arranged. When a certain high temperature is reached, the crystallization reaction is degraded, and the constant temperature platforms at 1550 to 1650 ° C, 1750 to 1850 ° C, and 2300 to 2400 ° C are kept at a constant temperature for a period of time. The atomic arrangement crystals are more uniform, that is, the graphite film thickness is more uniform after the graphitization is completed, and the probability of surface fracture, particles and the like is greatly reduced.
  • a graphitized gradient heating program is designed, and the two-stage temperature rising program cooperates to form a graphite film with high orientation, high crystallinity and high conductivity.
  • the ratio between the thickness of the PI film and the target thickness of the graphite film product in the step (1) is 1.85 to 2.35:1, for example, 1.85:1, 1.88:1, 1.90:1, 1.92:1, 1.95: 1, 2.00:1, 2.15:1, 2.25:1 or 2.35:1, and the like.
  • the thickness of the PI film in the step (1) is 39 to 40 ⁇ m, for example, 39 ⁇ m, 39.1 ⁇ m, 39.2 ⁇ m, 39.3 ⁇ m, 39.4 ⁇ m, 39.5 ⁇ m, 39.6 ⁇ m, 39.7 ⁇ m, 39.8 ⁇ m, 39.9 ⁇ m or 40 ⁇ m, and the like.
  • the thickness of the PI film in the step (1) is 53 to 54 ⁇ m, for example, 53 ⁇ m, 53.1 ⁇ m, 53.2 ⁇ m, 53.3 ⁇ m, 53.4 ⁇ m, 53.5 ⁇ m, 53.6 ⁇ m, 53.7 ⁇ m, 53.8 ⁇ m, 53.9 ⁇ m or 54 ⁇ m, and the like.
  • the thickness of the PI film in the step (1) is 74 to 75 ⁇ m, for example, 74 ⁇ m, 74.1 ⁇ m, 74.2 ⁇ m, 74.3 ⁇ m, 74.4 ⁇ m, 74.5 ⁇ m, 74.6 ⁇ m, 74.7 ⁇ m, 74.8 ⁇ m, 74.9 ⁇ m or 75 ⁇ m, and the like.
  • the sintering process of the related art is not perfect. If a graphite film with a high degree of carbonization is desired, the thickness of the raw material cannot be too thick, so that the sintered density cannot be simultaneously satisfied; on the contrary, if the sintered density is pursued, the thickness of the raw material must be increased, but due to the sintering process Insufficient, the degree of carbonization of the graphite film has to be sacrificed.
  • the thickness of the raw material PI film of the 17 ⁇ m graphite film is generally up to 37 to 38 ⁇ m
  • the thickness of the raw material PI film of the 25 ⁇ m graphite film is generally up to 49 to 50 ⁇ m
  • the thickness of the raw material PI film of the 40 ⁇ m graphite film is generally up to 49 to 50 ⁇ m.
  • the thickness of the raw material PI film of the embodiment of the present invention can be larger than that of the related art.
  • the thickness of the PI film is further increased. The sintering density of the graphite film is improved, and the conductivity of the graphite film can be ensured.
  • the carbonization in step (1) is carried out in a carbonization furnace.
  • the internal gas pressure of the carbonization furnace in the carbonization process in the step (1) is -1 to -0.5 MPa, for example, -1 MPa, -0.9 MPa, -0.8 MPa, -0.7 MPa, -0.6 MPa or -0.5 MPa, and the like.
  • the step (1) is heated to 650-750 ° C in such a manner that the PI film is first heated to 250-350 ° C, the temperature is kept for 20-60 min, and the temperature is further increased to 650-750 ° C.
  • the step (1) is heated to 650-750 ° C by heating the PI film to 250-350 ° C, constant temperature for 20-60 min, then heating to 350-450 ° C, constant temperature 40-80 min, and continuing to raise the temperature to 650. ⁇ 750 ° C.
  • the rate of raising the temperature to 250-350 ° C in step (1) is 6-10 ° C / min, such as 6 ° C / min, 6.5 ° C / min, 7 ° C / min, 7.5 ° C / min, 8 ° C / min 8.5 ° C / min, 9 ° C / min, 9.5 ° C / min or 10 ° C / min and so on.
  • the rate of the temperature rise to 350-450 ° C in step (1) is 1.5-3.5 ° C / min, such as 1.5 ° C / min, 1.8 ° C / min, 2.0 ° C / min, 2.2 ° C / min, 2.5 ° C / min 2.8 ° C / min, 3.2 ° C / min or 3.5 ° C / min and so on.
  • the rate of the temperature rise to 650-750 ° C in step (1) is 0.5-1 ° C / min, such as 0.5 ° C / min, 0.6 ° C / min, 0.7 ° C / min, 0.8 ° C / min, 0.9 ° C / min Or 1 ° C / min.
  • the rate of raising the temperature to 850 ° C to 950 ° C in step (1) is 0.3 to 0.7 ° C / min, such as 0.3 ° C / min, 0.4 ° C / min, 0.5 ° C / min, 0.6 ° C / min or 0.7 ° C / Min et al.
  • the rate of the temperature rise to 1250 to 1350 ° C in the step (1) is 2.5 to 5 ° C / min, for example, 2.5 ° C / min, 2.8 ° C / min, 3.0 ° C / min, 3.2 ° C / min, 3.5 ° C / min 3.8 ° C / min, 4.0 ° C / min, 4.2 ° C / min, 4.5 ° C / min, 4.8 ° C / min or 5 ° C / min and so on.
  • the step (2) is heated to a temperature of 1750 to 1850 ° C in such a manner that the carbonized film is first heated to 1550 to 1650 ° C, and the temperature is maintained for 20 to 60 minutes, and the temperature is further increased to 1750 to 1850 ° C.
  • the step (2) is heated to a temperature of 1750 to 1850 ° C by heating the carbonized film to 950 to 1050 ° C, maintaining a temperature of 10 to 15 minutes, continuing to raise the temperature to 1550 to 1650 ° C, and maintaining a constant temperature of 20 to 60 minutes. To 1750 ⁇ 1850 ° C.
  • the rate of the temperature rise to 950-1050 ° C in step (2) is 12.5-20 ° C / min, such as 12.5 ° C / min, 13 ° C / min, 13.5 ° C / min, 14 ° C / min, 14.5 ° C / min , 15 ° C / min, 15.5 ° C / min, 16 ° C / min, 16.5 ° C / min, 17 ° C / min, 17.5 ° C / min, 18 ° C / min, 18.5 ° C / min, 19 ° C / min, 19.5 ° C / min Or 20 ° C / min and so on.
  • the method of raising the temperature to 1550-1650 ° C in the step (2) is: first raising the temperature to 1150 to 1250 ° C at a rate of 3 to 4 ° C / min, for example, 3 ° C / min, 3.2 ° C / min, 3.5 ° C / Min, 3.8 ° C / min or 4 ° C / min, etc.; then increase the temperature to 1550 ⁇ 1650 ° C at 4 ⁇ 8 ° C / min, such as 4 ° C / min, 4.5 ° C / min, 5 ° C / min, 5.5 ° C / min , 6 ° C / min, 6.5 ° C / min, 7 ° C / min, 7.5 ° C / min or 8 ° C / min and so on.
  • the rate of the temperature rise to 1750 to 1850 ° C in the step (2) is 2 to 5 ° C / min, for example, 2 ° C / min, 2.2 ° C / min, 2.5 ° C / min, 2.8 ° C / min, 3 ° C / min 3.2 ° C / min, 3.5 ° C / min, 3.8 ° C / min, 4 ° C / min, 4.2 ° C / min, 4.5 ° C / min, 4.8 ° C / min or 5 ° C / min and so on.
  • the method of raising the temperature to 2300 to 2400 ° C in the step (2) is: first raising the temperature to 2050 to 2150 ° C, constant temperature for 20 to 90 minutes, and further increasing the temperature to 2300 to 2400 ° C.
  • the rate of the temperature rise to 2050-2150 ° C in step (2) is 3-10 ° C / min, such as 3 ° C / min, 4 ° C / min, 5 ° C / min, 6 ° C / min, 7 ° C / min , 8 ° C / min, 9 ° C / min or 10 ° C / min and so on.
  • the rate of raising the temperature to 2300 to 2400 ° C in step (2) is 2.5 to 5 ° C / min, such as 2.5 ° C / min, 2.8 ° C / min, 3 ° C / min, 3.2 ° C / min, 3.5 ° C / min 3.8 ° C / min, 4 ° C / min, 4.2 ° C / min, 4.5 ° C / min, 4.8 ° C / min or 5 ° C / min and so on.
  • the rate of the temperature rise to 2750-2900 ° C in the step (2) is 2 to 4 ° C / min, for example, 2 ° C / min, 2.2 ° C / min, 2.3 ° C / min, 2.5 ° C / min, 2.8 ° C / min , 3 ° C / min, 3.2 ° C / min, 3.5 ° C / min, 3.8 ° C / min or 4 ° C / min and so on.
  • the temperature further comprises: a constant temperature of 0 to 90 min.
  • the graphitization of step (2) is carried out in a graphitization furnace.
  • the graphitization of step (2) is carried out in an inert atmosphere.
  • the method for preparing the graphite film comprises the following steps:
  • Carbonization is carried out in a carbonization furnace with a PI membrane as a raw material and an internal gas pressure of -1 to -0.5 MPa using the following gradient heating procedure:
  • the PI film is heated to 250-350 ° C, the rate is 6 ⁇ 10 ° C / min, constant temperature 20 ⁇ 60min, continue to raise the temperature to 350 ⁇ 450 ° C, the rate is 1.5 ⁇ 3.5 ° C / min, constant temperature 40 ⁇ 80min, continue to heat up to 650 ⁇ 750 ° C, the rate is 0.5 ⁇ 1 ° C / min, constant temperature 100 ⁇ 150min, continue to raise the temperature to 850 ° C ⁇ 950 ° C, the rate is 0.3 ⁇ 0.7 ° C / min, constant temperature 100 ⁇ 150min, continue to raise the temperature to 1250 ⁇ 1350 ° C, the rate 2.5 to 5 ° C / min, constant temperature 80 ⁇ 130min, cooling, to obtain a carbonized film;
  • the carbonized film is heated to 950 to 1050 ° C, the rate is 12.5 ⁇ 20 ° C / min, the temperature is 10 ⁇ 15min, and the temperature is further increased to 1150 ⁇ 1250 ° C at a rate of 3 ⁇ 4 ° C / min, followed by 4 ⁇ 8 ° C /
  • the rate of min is raised to 1550 ⁇ 1650 ° C, constant temperature 20 ⁇ 60min, continue to raise the temperature to 1750 ⁇ 1850 ° C, the rate is 2 ⁇ 5 ° C / min, constant temperature 20 ⁇ 90min, continue to heat up to 2050 ⁇ 2150 ° C, the rate is 3 ⁇ 10 °C / min, constant temperature 20 ⁇ 90min, continue to raise the temperature to 2300 ⁇ 2400 ° C, the rate is 2.5 ⁇ 5 ° C / min, constant temperature 20 ⁇ 90min, continue to heat up to 2750 ⁇ 2900 ° C, the rate is 2 ⁇ 4 ° C / min, constant temperature
  • the embodiment of the invention provides a graphite film prepared by the method for preparing a graphite film according to the first aspect.
  • the graphite film has a thermal conductivity greater than 1300 W/(m ⁇ K).
  • the embodiment of the present invention provides the use of the graphite film according to the second aspect, wherein the graphite film is used for a heat conductive film, a conductive film, a signal shielding film, and a wear resistant material.
  • the embodiments of the present invention have at least the following beneficial effects:
  • a carbonization gradient heating program is designed to form an appropriate dynamic temperature field to obtain a high crystallinity carbonization structure; on the basis of carbonization, a graphitization gradient heating program is further designed, and the two-stage temperature rising program cooperates with each other. , forming a high orientation, high crystallinity, high conductivity graphite film, 17 ⁇ m graphite film thermal conductivity greater than 1700W / (m ⁇ K), 25 ⁇ m graphite film thermal conductivity greater than 1500W / (m ⁇ K), 40 ⁇ m graphite film thermal conductivity greater than 1300W/(m ⁇ K);
  • the method for preparing the graphite film of the embodiment of the invention has good repeatability, and can realize quantitative production of graphite films with different thicknesses;
  • the raw material PI film of the embodiment of the present invention can be thicker than the related art, and the carbonization and graphitization processes of the embodiment of the present invention are combined.
  • increasing the thickness of the PI film further increases the sintering density of the graphite film, and at the same time ensures the conductivity of the graphite film.
  • the present application enumerates the embodiments as follows. It should be understood by those skilled in the art that the embodiments are only used to help the understanding of the present application and should not be construed as a limitation.
  • a method for preparing a graphite film comprising the steps of:
  • Carbonization was carried out in a carbonization furnace having a thickness of 39 ⁇ m as a raw material and an internal gas pressure of -1 MPa using the following gradient heating procedure:
  • the PI membrane was placed in a carbonization furnace, and the temperature was raised to 300 ° C at a rate of 6 ° C / min, the temperature was maintained for 30 min, and the temperature was further increased to 400 ° C at a rate of 1.5 ° C / min, the temperature was maintained for 60 min, and the temperature was further increased to 700 ° C at a rate of 0.5 ° C / min.
  • Constant temperature 130min continue to increase the temperature to 900 ° C at a rate of 0.3 ° C / min, constant temperature 120min, continue to increase the temperature to 1300 ° C at a rate of 2.5 ° C / min, constant temperature 100min, cooling, to obtain a carbonized film;
  • the carbonized film was placed in a graphitization furnace, heated to 1000 ° C at a rate of 20 ° C / min under an argon atmosphere, kept at a constant temperature for 10 min, and further heated to a temperature of 4 ° C / min to 1200 ° C, followed by 8 ° C / min
  • the temperature is raised to 1600 ° C, the temperature is 35 min, and the temperature is raised to 1800 ° C at a rate of 5 ° C / min, the temperature is 35 min, and the temperature is raised to 2100 ° C at a rate of 10 ° C / min, the temperature is 35 min, and the temperature is raised to 2350 ° C at a rate of 5 ° C / min.
  • the temperature was further raised to 2750 ° C at a rate of 4 ° C / min, the temperature was kept for 60 min, and cooled to obtain a graphite film.
  • a method for preparing a graphite film comprising the steps of:
  • Carbonization was carried out in a carbonization furnace having a thickness of 40 ⁇ m as a raw material and an internal gas pressure of -0.5 MPa using the following gradient heating procedure:
  • the PI membrane was placed in a carbonization furnace, and the temperature was raised to 300 ° C at a rate of 10 ° C / min, the temperature was maintained for 30 min, and the temperature was further increased to 400 ° C at a rate of 3.5 ° C / min, the temperature was maintained for 60 min, and the temperature was further increased to 700 ° C at a rate of 1 ° C / min.
  • Constant temperature 130min continue to increase the temperature to 900 ° C at a rate of 0.7 ° C / min, constant temperature 120min, continue to increase the temperature to 1300 ° C at 5 ° C / min, constant temperature 100min, cooling, to obtain a carbonized film;
  • the carbonized film was placed in a graphitization furnace, heated to 1000 ° C at a rate of 12. ° C / min under an argon atmosphere, kept at a constant temperature for 10 min, and further heated to a temperature of 3 ° C / min to 1200 ° C, followed by 4 ° C / min
  • the temperature is raised to 1600 ° C, the temperature is 35 min, and the temperature is raised to 1800 ° C at a rate of 2 ° C / min, the temperature is 35 min, and the temperature is further increased to 2100 ° C at a rate of 3 to 10 ° C / min, the temperature is 35 min, and the temperature is further increased at a rate of 2.5 ° C / min.
  • the temperature was raised to 2,350 ° C to 2,750 ° C at a rate of 2 ° C / min, and the temperature was maintained for 60 min, and cooled to obtain a graphite film.
  • Example 1 The only difference from Example 1 is that the thickness of the PI film is 37 ⁇ m.
  • Example 1 The only difference from Example 1 is that the thickness of the PI film is 42 ⁇ m.
  • a method for preparing a graphite film comprising the steps of:
  • Carbonization was carried out in a carbonization furnace having a thickness of 53 ⁇ m as a raw material and an internal gas pressure of -0.8 MPa using the following gradient heating procedure:
  • the PI membrane was placed in a carbonization furnace, and the temperature was raised to 350 ° C at a rate of 7 ° C / min, the temperature was maintained for 30 min, and the temperature was further increased to 450 ° C at a rate of 2 ° C / min, the temperature was maintained for 60 min, and the temperature was further increased to 750 ° C at a rate of 0.6 ° C / min.
  • constant temperature for 130 min continue to increase the temperature to 950 ° C at a rate of 0.4 ° C / min
  • constant temperature for 120 min continue to increase the temperature to 1350 ° C at a rate of 3 ° C / min, constant temperature for 100 min, and cool to obtain a carbonized film;
  • the carbonized film was placed in a graphitization furnace, and the temperature was raised to 1050 ° C at a rate of 15 ° C / min under an argon atmosphere, and the temperature was raised for 15 minutes, and the temperature was further increased to 1250 ° C at a rate of 3.2 ° C / min, followed by 5 ° C / min.
  • the temperature is raised to 1650 ° C, constant temperature 60 min, continue to increase to 3850 ° C at 3 ° C / min, constant temperature 35 min, continue to increase the temperature to 2150 ° C at 5 ° C / min, constant temperature 90 min, continue to increase the temperature to 2300 ° C at 3 ° C / min At a constant temperature of 90 min, the temperature was raised to 2900 ° C at a rate of 2.5 ° C / min, the temperature was maintained for 90 min, and cooled to obtain a graphite film.
  • Example 5 The only difference from Example 5 is that the thickness of the PI film is 54 ⁇ m.
  • Example 5 The only difference from Example 5 is that the thickness of the PI film is 49 ⁇ m.
  • Example 5 The only difference from Example 5 is that the thickness of the PI film is 56 ⁇ m.
  • a method for preparing a graphite film comprising the steps of:
  • Carbonization was carried out in a carbonization furnace having a thickness of 74 ⁇ m as a raw material and an internal gas pressure of -0.6 MPa using the following gradient heating procedure:
  • the PI membrane was placed in a carbonization furnace, and the temperature was raised to 250 ° C at a rate of 8 ° C / min, the temperature was maintained for 20 min, and the temperature was further increased to 350 ° C at a rate of 3 ° C / min, the temperature was maintained for 40 min, and the temperature was further increased to 650 ° C at a rate of 0.8 ° C / min.
  • constant temperature for 100 min continue to increase the temperature to 850 ° C at a rate of 0.6 ° C / min
  • constant temperature for 150 min continue to increase the temperature to 1250 ° C at a rate of 4 ° C / min, constant temperature 130 min, cooling, to obtain a carbonized film;
  • the carbonized film was placed in a graphitization furnace, heated to 950 ° C at a rate of 18 ° C / min under an argon atmosphere, kept at a constant temperature for 10 min, and further heated to a temperature of 3.7 ° C / min to 1150 ° C, followed by 4.6 ° C / min
  • the temperature is raised to 1550 ° C, constant temperature for 35 min, continue to increase to 4750 ° C at a rate of 4 ° C / min, constant temperature 35 min, continue to increase the temperature to 2050 ° C at 8 ° C / min, constant temperature 35 min, continue to increase the temperature to 2300 ° C at 4 ° C / min
  • the temperature was raised to 2800 ° C at a rate of 3.5 ° C / min, the temperature was maintained for 60 min, and cooled to obtain a graphite film.
  • Example 9 The only difference from Example 9 is that the thickness of the PI film is 75 ⁇ m.
  • Example 9 The only difference from Example 9 is that the thickness of the PI film is 71 ⁇ m.
  • Example 9 The only difference from Example 9 is that the thickness of the PI film is 77 ⁇ m.
  • the only difference from the embodiment 9 is that the temperature is not controlled at 250 ° C in the step (1).
  • the only difference from the embodiment 9 is that the temperature is not controlled at 350 ° C in the step (1).
  • the only difference from the embodiment 9 is that the temperature is not maintained at 950 ° C in the step (2).
  • the only difference from the embodiment 9 is that the temperature is not maintained at 2050 ° C in the step (2).
  • step (1) neither 250 ° C nor 350 ° C is thermostated, and in step (2), 950 ° C and 2050 ° C are not thermostated.
  • Example 9 The only difference from Example 9 is that the temperature is not controlled at 650 ° C in the step (1).
  • the only difference from the embodiment 9 is that the temperature is not controlled at 850 ° C in the step (1).
  • the only difference from the embodiment 9 is that the temperature is not controlled at 1250 ° C in the step (1).
  • the only difference from the embodiment 9 is that the temperature is not maintained at 1550 ° C in the step (2).
  • the only difference from the embodiment 9 is that the temperature is not controlled at 1750 ° C in the step (2).
  • the only difference from the embodiment 9 is that the temperature is not controlled at 2300 ° C in the step (2).
  • the thickness of the graphite film was tested by a spiral micrometer, and the test results are shown in Table 1;
  • the thermal diffusion coefficient of the graphite film was detected by the German LFA447 Nanofalsh laser thermal conductivity meter, and the thermal conductivity of the graphite film was calculated according to the detected thermal diffusion coefficient. The results are shown in Table 1;
  • the carbonization yield (C%) of the graphite film was measured.
  • the carbonization yield was calculated by (Wz/W1) ⁇ 100%, and the results are shown in Table 1.
  • Example 1 17 2.056 1784.35 54% 25
  • Example 2 17 2.112 1836.23 53% 26
  • Example 3 16 2.085 1712.57 52% twenty three
  • Example 4 18 2.056 1721.68 53% 27
  • Example 5 twenty three 1.985 1679.28 55% 26
  • Example 6 twenty three 2.044 1724.83 53% 27
  • Example 7 twenty three 1.834 1546.27 53% twenty four
  • Example 8 25 1.867 1571.62 52%
  • Example 9 38 1.859 1382.36 53% 25
  • Example 10 38 1.877 1416.24 53% 27
  • Example 11 38 1.546 1330.56 51% twenty four
  • Example 12 40 1.814 1354.67 54%
  • Example 13 38 1.811 1334.41 52% 25
  • Example 15 38 1.796 1313.55 52% 26
  • Example 16 38 1.834 1348.13 53% twenty four
  • Example 9 Comparing Example 9, Examples 13 to 17, and Comparative Examples 9-1 to 9-6, it can be seen that the embodiment of the present invention designs a carbonization gradient temperature program, 650 to 750 ° C, 850 ° C to 950 ° C, and 1250 to 1350 ° C.
  • a constant temperature platform can properly buffer the release of heterocyclic atoms during carbonization, preventing C atoms from being taken away when the hetero atom is severely excluded, and reducing defects such as intramolecular cleavage.
  • the impurity removal rate in the carbonization stage is increased while reducing defects such as intramolecular wrinkles or fractures, and a carbonized structure having high crystallinity is obtained.
  • the graphitization gradient heating program is further designed, and the C atoms are arranged and crystallized more uniformly at a constant temperature of 1550 ⁇ 1650 ° C, 1750 ⁇ 1850 ° C, 2300 ⁇ 2400 ° C for a period of time, that is, the graphitization is completed.
  • the thickness of the post-graphite film is more uniform, and the probability of surface breakage, particle and other defects is greatly reduced.
  • the two-stage heating process cooperates with each other to form a graphite film with high orientation, high crystallinity and high conductivity.
  • the thermal conductivity of the 17 ⁇ m graphite film is greater than 1700W/(m ⁇ K), and the thermal conductivity of the 25 ⁇ m graphite film is greater than 1500W/(m). ⁇ K), 40 ⁇ m graphite film thermal conductivity greater than 1300W / (m ⁇ K). Omission of any of the necessary temperature risers will result in a significant decrease in thermal conductivity, density, carbonization yield, and mechanical properties of the graphite film.

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Abstract

石墨膜的制备方法，其包括：(1)碳化：将PI膜升温至650～750℃，恒温100～150min，继续升温至850℃～950℃，恒温100～150min，继续升温至1250～1350℃，恒温80～130min，冷却，得到碳化膜；(2)石墨化：将步骤(1)所得碳化膜采用如下梯度升温程序进行石墨化：将所述碳化膜升温至1550～1650℃，恒温20～60min，继续升温至1750～1850℃，恒温20～90min，继续升温至2300～2400℃，恒温20～90min，升温至2750～2900℃，冷却，得到高取向、高结晶度、高传导性能的石墨膜。

Description

一种石墨膜的制备方法及其产品和用途 技术领域
本申请涉及导热材料技术领域，具体涉及一种石墨膜的制备方法及其产品和用途。
背景技术
随着科学技术的不断发展，散热问题成为许多领域发展遇到的一个共同难题。例如，在大型笔记本电脑CPU、手机，以及许多家用电器中电子元件的高集成化、高密度化，使得材料表面产生的热量急剧增加，如不能及时将热量排除则会影响电子元件的寿命和系统的稳定性。另外，在导弹鼻锥体、固体火箭发动机喷管、航天飞行器热控系统以及核聚变反应等领域，除热问题也是亟待解决的科技难关。炭、石墨材料具有较高的热导率，优良的机械性能，低密度、低热膨胀系数等，被认为是解决以上难题的优良材料，具备很大的发展潜力。
高定向石墨因其高定向性层状结构，具有良好的导热性能，在许多领域更显示了其不可替代的优越性能。最初的高定向石墨是由热解法合成，被称为高定向热解石墨，它是由热解炭在应力作用下高温热处理而得。但热解石墨的制备工艺较为复杂，使得材料十分昂贵，极大地限制了其应用。上世纪70代初期，科学家发现，通过将聚酰亚胺(PI)在惰性气氛下加压炭化，并经2800～3200℃石墨化处理可制得石墨，所制样品具有与高定向热解石墨一样的高结晶度和沿膜表面高度择优的石墨层取向。采用PI制备具有高定向石墨极大的简化制备工艺，节约了成本，大大的降低了高定向石墨的成本。但是采用PI制得的高定向石墨存在着一定的缺陷，例如其在碳化或石墨化过程中容易发生卷曲，导致最终产品脆性大，同时还存在着碳化程度低、断裂强度差、导热和导电性差的缺陷，这些问题极大的限制了其应用。
CN103011141A公开了一种高导热石墨膜的制造方法，采用PI薄膜作为原材料，将PI薄膜和石墨纸切割成固定尺寸，将切割成规定尺寸的PI薄膜层层叠放成确定高度，在每一层聚酞亚胺薄膜之间加入石墨纸：将间隔有石墨纸交叉层叠后PI薄膜放入碳化炉中，在惰性气体保护下，分别在1000-1400℃下，以及2500-3000℃下进行碳化和石墨化，得到高导热的石墨膜。增强了石墨膜的抗弯曲性能，降低了石墨膜的脆性，但是对石墨膜的碳化程度、断裂强度、导电性和导热性并没有改进。
CN107311661A公开了一种复合石墨膜的制备方法，包括：制备由纳米金刚石和PI形成的复合薄膜；在惰性气体保护下，进行碳化和石墨化处理，然后去除石墨纸，得到由纳米金刚石和PI形成的复合石墨膜。在碳化和石墨化过程中，纳米金刚石作为晶核促进PI的碳化和石墨化，提高石墨化度和碳化产率，从而提高复合碳膜的导热性能、导电性。但导热率最高只有1056W/(m·K)，有待提高，且纳米金刚石的分散程度会导致石墨的晶体结构均匀性难以控制，产品性能稳定性不够好，且金刚石增加成本，不适于放大生产。
因此，需要开发一种石墨膜的制备方法，进一步提高石墨膜的导热性，且工艺可控性高，重复性佳，适于量产各种厚度的高导热石墨膜。
发明内容
以下是对本文详细描述的主题的概述。本概述并非是为了限制权利要求的保护范围。
本申请的目的之一是提供一种石墨膜的制备方法，进一步提高石墨膜的导热性，且工艺可控性高，重复性佳，适于量产各种厚度的高导热石墨膜。
为达此目的，本发明实施例采用如下技术方案：
第一方面，本发明实施例提供一种石墨膜的制备方法，包括如下步骤：
(1)碳化：以PI膜为原料，采用如下梯度升温程序进行碳化：
将PI膜升温至650～750℃，恒温100～150min，继续升温至850℃～950℃，恒温100～150min，继续升温至1250～1350℃，恒温80～130min，冷却，得到碳化膜；
(2)石墨化：将步骤(1)所得碳化膜采用如下梯度升温程序进行石墨化：
将所述碳化膜升温至1550～1650℃，恒温20～60min，继续升温至1750～1850℃，恒温20～90min，继续升温至2300～2400℃，恒温20～90min，升温2750～2900℃，冷却，得到石墨膜。
PI膜的碳化阶段主要是发生热解，释放出CO和CO 2，且N、O等杂原子逐渐释放出来，PI的分子链结构发生断裂和重组，随着原料膜逐渐向晶体结构转变，衍生出类石墨结构，其力学和热传导、电传导性能出现不可预期的转折，本发明实施例通过设计碳化的梯度升温程序，形成恰当的动态温度场，三个恒温平台使得碳化过程中释放杂环原子时得以适当缓冲，防止因剧烈排除杂环原子时带走C原子，减少分子内断裂等缺陷。最终提高碳化阶段的杂质去除率的同时减少分子内褶皱或断裂等缺陷，获得高结晶度的碳化结构。
石墨化阶段相较于碳化阶段温度高得多，主要将碳六角网络进行有序化，反应场中发生复杂的三相转变和碳的再结晶过程，在此阶段初期也会进一步排除杂环原子，随着温度升高C原子排列结晶越迅速剧烈，达到一定高温时排列结晶反应又衰退，而在1550～1650℃、1750～1850℃、2300～2400℃这几个恒温平台恒温一段时间使C原子排列结晶更加均匀，即石墨化完成后石墨膜厚度更均匀，出现表面断裂、颗粒等缺陷的概率大大降低。
本发明实施例在碳化的基础上，设计石墨化的梯度升温程序，两阶段升温程序互相配合，形成高取向、高结晶度、高传导性能的石墨膜。
优选地，步骤(1)所述PI膜的厚度与石墨膜产品的目标厚度之间之比为 1.85～2.35∶1，例如1.85∶1、1.88∶1、1.90∶1、1.92∶1、1.95∶1、2.00∶1、2.15∶1、2.25∶1或2.35∶1等。
优选地，当石墨膜产品的目标厚度为17μm时，步骤(1)所述PI膜的厚度为39～40μm，例如39μm、39.1μm、39.2μm、39.3μm、39.4μm、39.5μm、39.6μm、39.7μm、39.8μm、39.9μm或40μm等。
优选地，当石墨膜产品的目标厚度为25μm时，步骤(1)所述PI膜的厚度为53～54μm，例如53μm、53.1μm、53.2μm、53.3μm、53.4μm、53.5μm、53.6μm、53.7μm、53.8μm、53.9μm或54μm等。
优选地，当石墨膜产品的目标厚度为40μm时，步骤(1)所述PI膜的厚度为74～75μm，例如74μm、74.1μm、74.2μm、74.3μm、74.4μm、74.5μm、74.6μm、74.7μm、74.8μm、74.9μm或75μm等。
相关技术的烧结工艺不完善，如果想要得到碳化程度高的石墨膜，则原料厚度不能太厚，从而烧结密度不能同时满足；反之，如果追求烧结密度，原料厚度必须增加，但由于烧结工艺的不足，则不得不牺牲石墨膜的碳化程度。
相关技术中17μm石墨膜的原材料PI膜厚度一般最多37～38μm，25μm石墨膜的原材料PI膜厚度一般最多49～50μm，40μm石墨膜的原材料PI膜厚度一般最多49～50μm。在石墨膜产品的目标厚度相同的情况下，本发明实施例的原料PI膜相较于相关技术厚度可以更大，本发明实施例的碳化和石墨化工艺配合的前提下，增加PI膜厚度进一步提高了石墨膜的烧结密度，同时能保证石墨膜的传导性能。
优选地，步骤(1)所述碳化在炭化炉中进行。
优选地，步骤(1)所述碳化过程中炭化炉的内部气压为-1～-0.5MPa，例如-1MPa、-0.9MPa、-0.8MPa、-0.7MPa、-0.6MPa或-0.5MPa等。
优选地，步骤(1)升温至650～750℃的方式为：将PI膜先升温至250～350℃，恒温20～60min，继续升温至650～750℃。
优选地，步骤(1)升温至650～750℃的方式为：将PI膜先升温至250～350℃，恒温20～60min，再升温至350～450℃，恒温40～80min，继续升温至650～750℃。
优选地，步骤(1)所述升温至250～350℃的速率为6～10℃/min，例如6℃/min、6.5℃/min、7℃/min、7.5℃/min、8℃/min、8.5℃/min、9℃/min、9.5℃/min或10℃/min等。
优选地，步骤(1)所述升温至350～450℃的速率为1.5～3.5℃/min，例如1.5℃/min、1.8℃/min、2.0℃/min、2.2℃/min、2.5℃/min、2.8℃/min、3.2℃/min或3.5℃/min等。
优选地，步骤(1)所述升温至650～750℃的速率为0.5～1℃/min，例如0.5℃/min、0.6℃/min、0.7℃/min、0.8℃/min、0.9℃/min或1℃/min。
优选地，步骤(1)所述升温至850℃～950℃的速率为0.3～0.7℃/min，例如0.3℃/min、0.4℃/min、0.5℃/min、0.6℃/min或0.7℃/min等。
优选地，步骤(1)所述升温至1250～1350℃的速率为2.5～5℃/min，例如2.5℃/min、2.8℃/min、3.0℃/min、3.2℃/min、3.5℃/min、3.8℃/min、4.0℃/min、4.2℃/min、4.5℃/min、4.8℃/min或5℃/min等。
优选地，步骤(2)升温至1750～1850℃的方式为：将所述碳化膜先升温至1550～1650℃，恒温20～60min，继续升温至1750～1850℃。
优选地，步骤(2)升温至1750～1850℃的方式为：将所述碳化膜先升温至950～1050℃，恒温10～15min，继续升温至1550～1650℃，恒温20～60min，继续升温至1750～1850℃。
优选地，步骤(2)所述升温至950～1050℃的速率为12.5～20℃/min，例如 12.5℃/min、13℃/min、13.5℃/min、14℃/min、14.5℃/min、15℃/min、15.5℃/min、16℃/min、16.5℃/min、17℃/min、17.5℃/min、18℃/min、18.5℃/min、19℃/min、19.5℃/min或20℃/min等。
优选地，步骤(2)所述升温至1550～1650℃的方式为：先以3～4℃/min的速率升温至1150～1250℃，例如3℃/min、3.2℃/min、3.5℃/min、3.8℃/min或4℃/min等；再以4～8℃/min的速率升温至1550～1650℃，例如4℃/min、4.5℃/min、5℃/min、5.5℃/min、6℃/min、6.5℃/min、7℃/min、7.5℃/min或8℃/min等。
优选地，步骤(2)所述升温至1750～1850℃的速率为2～5℃/min，例如2℃/min、2.2℃/min、2.5℃/min、2.8℃/min、3℃/min、3.2℃/min、3.5℃/min、3.8℃/min、4℃/min、4.2℃/min、4.5℃/min、4.8℃/min或5℃/min等。
优选地，步骤(2)所述升温至2300～2400℃的方式为：先升温至2050～2150℃，恒温20～90min，再升温至2300～2400℃。
优选地，步骤(2)所述升温至2050～2150℃的速率为3～10℃/min，例如3℃/min、4℃/min、5℃/min、6℃/min、7℃/min、8℃/min、9℃/min或10℃/min等。
优选地，步骤(2)所述升温至2300～2400℃的速率为2.5～5℃/min，例如2.5℃/min、2.8℃/min、3℃/min、3.2℃/min、3.5℃/min、3.8℃/min、4℃/min、4.2℃/min、4.5℃/min、4.8℃/min或5℃/min等。
优选地，步骤(2)所述升温至2750～2900℃的速率为2～4℃/min，例如2℃/min、2.2℃/min、2.3℃/min、2.5℃/min、2.8℃/min、3℃/min、3.2℃/min、3.5℃/min、3.8℃/min或4℃/min等。
优选地，步骤(2)所述升温至2750～2900℃之后还包括：恒温0～90min。
优选地，步骤(2)所述石墨化在石墨化炉中进行。
优选地，步骤(2)所述石墨化在惰性气氛中进行。
作为本发明实施例优选的技术方案，所述石墨膜的制备方法包括如下步骤：
(1)碳化：以PI膜为原料，内部气压为-1～-0.5MPa的炭化炉中采用如下梯度升温程序进行碳化：
将PI膜升温至250～350℃，速率为6～10℃/min，恒温20～60min，继续升温至350～450℃，速率为1.5～3.5℃/min，恒温40～80min，继续升温至650～750℃，速率为0.5～1℃/min，恒温100～150min，继续升温至850℃～950℃，速率为0.3～0.7℃/min，恒温100～150min，继续升温至1250～1350℃，速率为2.5～5℃/min，恒温80～130min，冷却，得到碳化膜；
(2)石墨化：将步骤(1)所得碳化膜置于石墨化炉中，惰性气氛中采用如下梯度升温程序进行石墨化：
将所述碳化膜升温至950～1050℃，速率为12.5～20℃/min，恒温10～15min，继续以3～4℃/min的速率升温至1150～1250℃，接着以4～8℃/min的速率升温至1550～1650℃，恒温20～60min，继续升温至1750～1850℃，速率为2～5℃/min，恒温20～90min，继续升温至2050～2150℃，速率为3～10℃/min，恒温20～90min，继续升温至2300～2400℃，速率为2.5～5℃/min，恒温20～90min，继续升温至2750～2900℃，速率为2～4℃/min，恒温0～90min，冷却，得到石墨膜。
第二方面，本发明实施例提供一种如第一方面所述的石墨膜的制备方法制备出的石墨膜。
优选地，所述石墨膜的导热系数大于1300W/(m·K)。
第三方面，本发明实施例提供如第二方面所述的石墨膜的用途，所述石墨膜用于导热膜、导电膜、信号屏蔽膜和耐磨材料。
与相关技术方案相比，本发明实施例至少具有如下有益效果：
1.本发明实施例通过设计碳化的梯度升温程序，形成恰当的动态温度场， 获得高结晶度的碳化结构；在碳化的基础上，进一步设计石墨化的梯度升温程序，两阶段升温程序互相配合，形成高取向、高结晶度、高传导性能的石墨膜，17μm石墨膜导热系数大于1700W/(m·K)，25μm石墨膜导热系数大于1500W/(m·K)，40μm石墨膜导热系数大于1300W/(m·K)；
2.本发明实施例的石墨膜的制备方法重复性好，可实现不同厚度石墨膜的量化生产；
3.在进一步优选的技术方案中，当石墨膜产品的目标厚度相同时，本发明实施例的原料PI膜相较于相关技术厚度可以更大，本发明实施例的碳化和石墨化工艺配合的前提下，增加PI膜厚度进一步提高了石墨膜的烧结密度，同时能保证石墨膜的传导性能。
具体实施方式
为便于理解本申请，本申请列举实施例如下。本领域技术人员应该明了，所述实施例仅仅用于帮助理解本申请，不应视为对本申请的具体限制。
实施例1
一种石墨膜的制备方法，包括如下步骤：
(1)碳化：以厚39μm的PI膜为原料，内部气压为-1MPa的炭化炉中采用如下梯度升温程序进行碳化：
将PI膜置于炭化炉中，以6℃/min速率升温至300℃，恒温30min，继续以1.5℃/min速率升温至400℃，恒温60min，继续以0.5℃/min速率升温至700℃，恒温130min，继续以0.3℃/min速率升温至900℃，恒温120min，继续以2.5℃/min速率升温至1300℃，恒温100min，冷却，得到碳化膜；
(2)石墨化：将步骤(1)所得碳化膜采用如下梯度升温程序进行石墨化：
将所述碳化膜置于石墨化炉中，氩气气氛下以20℃/min速率升温至1000℃， 恒温10min，继续以4℃/min的速率升温至1200℃，接着以8℃/min的速率升温至1600℃，恒温35min，继续以5℃/min速率升温至1800℃，恒温35min，继续以10℃/min速率升温至2100℃，恒温35min，继续以5℃/min速率升温至2350℃，恒温35min，继续以4℃/min的速率升温至2750℃，恒温60min，冷却，得到石墨膜。
实施例2
一种石墨膜的制备方法，包括如下步骤：
(1)碳化：以厚40μm的PI膜为原料，内部气压为-0.5MPa的炭化炉中采用如下梯度升温程序进行碳化：
将PI膜置于炭化炉中，以10℃/min速率升温至300℃，恒温30min，继续以3.5℃/min速率升温至400℃，恒温60min，继续以1℃/min速率升温至700℃，恒温130min，继续以0.7℃/min速率升温至900℃，恒温120min，继续以5℃/min速率升温至1300℃，恒温100min，冷却，得到碳化膜；
(2)石墨化：将步骤(1)所得碳化膜采用如下梯度升温程序进行石墨化：
将所述碳化膜置于石墨化炉中，氩气气氛下以12.℃/min速率升温至1000℃，恒温10min，继续以3℃/min的速率升温至1200℃，接着以4℃/min的速率升温至1600℃，恒温35min，继续以2℃/min速率升温至1800℃，恒温35min，继续以3～10℃/min速率升温至2100℃，恒温35min，继续以2.5℃/min速率升温至2350℃，恒温35min，继续以2℃/min的速率升温至2750℃，恒温60min，冷却，得到石墨膜。
实施例3
与实施例1的区别仅在于：PI膜的厚度为37μm。
实施例4
与实施例1的区别仅在于：PI膜的厚度为42μm。
实施例5
一种石墨膜的制备方法，包括如下步骤：
(1)碳化：以厚53μm的PI膜为原料，内部气压为-0.8MPa的炭化炉中采用如下梯度升温程序进行碳化：
将PI膜置于炭化炉中，以7℃/min速率升温至350℃，恒温30min，继续以2℃/min速率升温至450℃，恒温60min，继续以0.6℃/min速率升温至750℃，恒温130min，继续以0.4℃/min速率升温至950℃，恒温120min，继续以3℃/min速率升温至1350℃，恒温100min，冷却，得到碳化膜；
(2)石墨化：将步骤(1)所得碳化膜采用如下梯度升温程序进行石墨化：
将所述碳化膜置于石墨化炉中，氩气气氛下以15℃/min速率升温至1050℃，恒温15min，继续以3.2℃/min的速率升温至1250℃，接着以5℃/min的速率升温至1650℃，恒温60min，继续以3℃/min速率升温至1850℃，恒温35min，继续以5℃/min速率升温至2150℃，恒温90min，继续以3℃/min速率升温至2300℃，恒温90min，继续以2.5℃/min的速率升温至2900℃，恒温90min，冷却，得到石墨膜。
实施例6
与实施例5的区别仅在于：PI膜的厚度为54μm。
实施例7
与实施例5的区别仅在于：PI膜的厚度为49μm。
实施例8
与实施例5的区别仅在于：PI膜的厚度为56μm。
实施例9
一种石墨膜的制备方法，包括如下步骤：
(1)碳化：以厚74μm的PI膜为原料，内部气压为-0.6MPa的炭化炉中采用如下梯度升温程序进行碳化：
将PI膜置于炭化炉中，以8℃/min速率升温至250℃，恒温20min，继续以3℃/min速率升温至350℃，恒温40min，继续以0.8℃/min速率升温至650℃，恒温100min，继续以0.6℃/min速率升温至850℃，恒温150min，继续以4℃/min速率升温至1250℃，恒温130min，冷却，得到碳化膜；
(2)石墨化：将步骤(1)所得碳化膜采用如下梯度升温程序进行石墨化：
将所述碳化膜置于石墨化炉中，氩气气氛下以18℃/min速率升温至950℃，恒温10min，继续以3.7℃/min的速率升温至1150℃，接着以4.6℃/min的速率升温至1550℃，恒温35min，继续以4℃/min速率升温至1750℃，恒温35min，继续以8℃/min速率升温至2050℃，恒温35min，继续以4℃/min速率升温至2300℃，恒温35min，继续以3.5℃/min的速率升温至2800℃，恒温60min，冷却，得到石墨膜。
实施例10
与实施例9的区别仅在于：PI膜的厚度为75μm。
实施例11
与实施例9的区别仅在于：PI膜的厚度为71μm。
实施例12
与实施例9的区别仅在于：PI膜的厚度为77μm。
实施例13
与实施例9的区别仅在于：步骤(1)中250℃不进行恒温。
实施例14
与实施例9的区别仅在于：步骤(1)中350℃不进行恒温。
实施例15
与实施例9的区别仅在于：步骤(2)中950℃不进行恒温。
实施例16
与实施例9的区别仅在于：步骤(2)中2050℃不进行恒温。
实施例17
与实施例9的区别仅在于：步骤(1)中250℃、350℃均不进行恒温且步骤(2)中950℃、2050℃也不进行恒温。
对比例9-1
与实施例9的区别仅在于：步骤(1)中650℃不进行恒温。
对比例9-2
与实施例9的区别仅在于：步骤(1)中850℃不进行恒温。
对比例9-3
与实施例9的区别仅在于：步骤(1)中1250℃不进行恒温。
对比例9-4
与实施例9的区别仅在于：步骤(2)中1550℃不进行恒温。
对比例9-5
与实施例9的区别仅在于：步骤(2)中1750℃不进行恒温。
对比例9-6
与实施例9的区别仅在于：步骤(2)中2300℃不进行恒温。
性能测试：
对各实施例和对比例制备的石墨膜的导电性、导热性、碳化收率以及断裂强度进行检测；
用真空密度仪对石墨膜进行密度进行测试，检测结果见表1；
用螺旋测微仪对石墨膜进行厚度测试，检测结果见表1；
用德国LFA447Nanofalsh激光法导热仪对石墨膜的面向热扩散系数进行检测，并且根据检测到的面向热扩散系数计算出石墨膜的导热率，结果见表1；
采用万能电子试验机对石墨膜的断裂强度进行检测，检测结果见表1；
检测石墨膜的碳化收率(C％)，每张石墨膜的检测方法为：称量PI膜的重量，记为W 1，称量石墨膜的重量，记为W 2，根据公式C％＝(Wz/W1)×100％计算得到碳化收率，结果见表1。
表1
石墨膜 厚度μm 密度g/cm 3 导热率W/(m·K) 碳化收率％ 断裂强度Mpa
实施例1 17 2.056 1784.35 54％ 25
实施例2 17 2.112 1836.23 53％ 26
实施例3 16 2.085 1712.57 52％ 23
实施例4 18 2.056 1721.68 53％ 27
实施例5 23 1.985 1679.28 55％ 26
实施例6 23 2.044 1724.83 53％ 27
实施例7 23 1.834 1546.27 53％ 24
实施例8 25 1.867 1571.62 52％ 27
实施例9 38 1.859 1382.36 53％ 25
实施例10 38 1.877 1416.24 53％ 27
实施例11 38 1.546 1330.56 51％ 24
实施例12 40 1.814 1354.67 54％ 26
实施例13 38 1.822 1355.62 53％ 25
实施例14 38 1.811 1334.41 52％ 25
实施例15 38 1.796 1313.55 52％ 26
实施例16 38 1.834 1348.13 53％ 24
实施例17 38 1.817 1320.56 51％ 23
对比例9-1 38 1.482 1025.84 47％ 16
对比例9-2 38 1.534 1064.51 50％ 17
对比例9-3 38 1.717 1153.76 48％ 22
对比例9-4 38 1.805 1241.86 51％ 23
对比例9-5 38 1.794 1208.77 52％ 20
对比例9-6 38 1.773 1195.19 52％ 20
对照实施例9、实施例13～17与对比例9-1～9-6可知，本发明实施例通过设 计碳化的梯度升温程序，650～750℃、850℃～950℃、1250～1350℃三个恒温平台使得碳化过程中释放杂环原子时得以适当缓冲，防止因剧烈排除杂环原子时带走C原子，减少分子内断裂等缺陷。最终提高碳化阶段的杂质去除率的同时减少分子内褶皱或断裂等缺陷，获得高结晶度的碳化结构。在碳化的基础上，进一步设计石墨化的梯度升温程序，在1550～1650℃、1750～1850℃、2300～2400℃这几个恒温平台恒温一段时间使C原子排列结晶更加均匀，即石墨化完成后石墨膜厚度更均匀，出现表面断裂、颗粒等缺陷的概率大大降低。两阶段升温程序互相配合，协同作用，形成高取向、高结晶度、高传导性能的石墨膜，其中17μm石墨膜导热系数大于1700W/(m·K)，25μm石墨膜导热系数大于1500W/(m·K)，40μm石墨膜导热系数大于1300W/(m·K)。省略必要升温平台中的任意一个都会使得石墨膜的导热系数、密度、碳化收率和机械性能显著下降。
对照实施例1～4，再对照实施例5～8的结果，然后对照实施例9～12的结果，可以得出相同的结论：在进一步优选的技术方案中，当石墨膜产品的目标厚度相同时，本发明实施例的原料PI膜相较于相关技术厚度可以更大，本发明实施例的碳化和石墨化工艺配合的前提下，增加PI膜厚度进一步提高了石墨膜的烧结密度，同时能保证石墨膜的传导性能，相关技术很难同时保证石墨膜的烧结密度和传导性能。
申请人声明，本申请通过上述实施例来说明本发明实施例的详细工艺设备和工艺流程，但本发明实施例并不局限于上述详细工艺设备和工艺流程，即不意味着本发明实施例必须依赖上述详细工艺设备和工艺流程才能实施。所属技术领域的技术人员应该明了，对本发明实施例的任何改进，对本发明实施例产品各原料的等效替换及辅助成分的添加、具体方式的选择等，均落在本申请的保护范围和公开范围之内。

Claims (12)

  1. 一种石墨膜的制备方法，其包括如下步骤：
    (1)碳化：以PI膜为原料，采用如下梯度升温程序进行碳化：
    将PI膜升温至650～750℃，恒温100～150min，继续升温至850℃～950℃，恒温100～150min，继续升温至1250～1350℃，恒温80～130min，冷却，得到碳化膜；
    (2)石墨化：将步骤(1)所得碳化膜采用如下梯度升温程序进行石墨化：
    将所述碳化膜升温至1550～1650℃，恒温20～60min，继续升温至1750～1850℃，恒温20～90min，继续升温至2300～2400℃，恒温20～90min，升温2750～2900℃，冷却，得到石墨膜。
  2. 如权利要求1所述的石墨膜的制备方法，其中，步骤(1)所述PI膜的厚度与石墨膜产品的目标厚度之间之比为1.85～2.35∶1。
  3. 如权利要求2所述的石墨膜的制备方法，其中，当石墨膜产品的目标厚度为17μm时，步骤(1)所述PI膜的厚度为39～40μm。
  4. 如权利要求2所述的石墨膜的制备方法，其中，当石墨膜产品的目标厚度为25μm时，步骤(1)所述PI膜的厚度为53～54μm；
    优选地，当石墨膜产品的目标厚度为40μm时，步骤(1)所述PI膜的厚度为74～75μm。
  5. 如权利要求1至4中任一项所述的石墨膜的制备方法，其中，步骤(1)所述碳化在炭化炉中进行；
    优选地，步骤(1)所述碳化过程中炭化炉的内部气压为-1～-0.5MPa。
  6. 如权利要求1～5任一项所述的石墨膜的制备方法，其中，步骤(1)升温至650～750℃的方式为：将PI膜先升温至250～350℃，恒温20～60min，继续升温至650～750℃；
    优选地，步骤(1)升温至650～750℃的方式为：将PI膜先升温至250～350℃，恒温20～60min，再升温至350～450℃，恒温40～80min，继续升温至650～750℃；
    优选地，步骤(1)所述升温至250～350℃的速率为6～10℃/min；
    优选地，步骤(1)所述升温至350～450℃的速率为1.5～3.5℃/min；
    优选地，步骤(1)所述升温至650～750℃的速率为0.5～1℃/min；
    优选地，步骤(1)所述升温至850℃～950℃的速率为0.3～0.7℃/min；
    优选地，步骤(1)所述升温至1250～1350℃的速率为2.5～5℃/min。
  7. 如权利要求1～6任一项所述的石墨膜的制备方法，其中，步骤(2)升温至1750～1850℃的方式为：将所述碳化膜先升温至1550～1650℃，恒温20～60min，继续升温至1750～1850℃；
    优选地，步骤(2)升温至1750～1850℃的方式为：将所述碳化膜先升温至950～1050℃，恒温10～15min，继续升温至1550～1650℃，恒温20～60min，继续升温至1750～1850℃；
    优选地，步骤(2)所述升温至950～1050℃的速率为12.5～20℃/min；
    优选地，步骤(2)所述升温至1550～1650℃的方式为：先以3～4℃/min的速率升温至1150～1250℃，再以4～8℃/min的速率升温至1550～1650℃；
    优选地，步骤(2)所述升温至1750～1850℃的速率为2～5℃/min。
  8. 如权利要求1～7任一项所述的石墨膜的制备方法，其中，步骤(2)所述升温至2300～2400℃的方式为：先升温至2050～2150℃，恒温20～90min，再升温至2300～2400℃；
    优选地，步骤(2)所述升温至2050～2150℃的速率为3～10℃/min；
    优选地，步骤(2)所述升温至2300～2400℃的速率为2.5～5℃/min；
    优选地，步骤(2)所述升温至2750～2900℃的速率为2～4℃/min；
    优选地，步骤(2)所述升温至2750～2900℃之后还包括：恒温0～90min。
  9. 如权利要求1～8任一项所述的石墨膜的制备方法，其中，步骤(2)所述石墨化在石墨化炉中进行；
    优选地，步骤(2)所述石墨化在惰性气氛中进行。
  10. 一种如权利要求1～9任一项所述的石墨膜的制备方法制备出的石墨膜。
  11. 如权利要求10所述的石墨膜，其中，所述石墨膜的导热系数大于1300W/(m·K)。
  12. 如权利要求10或11所述的石墨膜的用途，其中，所述石墨膜用于导热膜、导电膜、信号屏蔽膜和耐磨材料。
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CN111559744A (zh) * 2020-06-19 2020-08-21 株洲时代新材料科技股份有限公司 一种高导热石墨材料的制备方法
CN112591743A (zh) * 2020-12-28 2021-04-02 碳元科技股份有限公司 超厚发泡石墨及其制备方法、导电发热材料
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