TW201912688A - Method of making carbonized film using a polyimide film as a precursor on which a carbonizing heat treatment is performed - Google Patents

Abstract

A method of making a carbonized film is provided. The method is characterized in that a polyimide film is used as a precursor, on which a carbonizing heat treatment is performed, wherein the condition of performing heat treatment is: the average heating rate during the carbonizing heat treatment within 500 to 800 degrees Celsius is equal to or lower than 2 degrees Celsius per minute. The highest carbonizing temperature is equal to or higher than 1000 degrees Celsius so as to form a carbonized film. The carbonized film is processed with a graphitizing heat treatment, in which the average heating rate for graphitization at 2200 degrees Celsius to the highest graphitizing temperature is equal to or lower than 3 degrees Celsius per minute, and the highest graphitizing temperature is equal to or higher than 2500 degrees Celsius to form a graphite film.

Description

 Carbonized film manufacturing method  

The present invention relates to a method for producing a carbonized film, in particular, a heat treatment to form a carbonized film using a polyimide film as a precursor, and a carbonized film having a better quality is obtained by controlling a temperature increase rate at a specific temperature range.

The rapid growth of mobile devices has made light and thin a trend toward electronic products, and electronic components have been densely packed in order to reduce the volume. Therefore, heat dissipation problems of wafers, backlight modules, and batteries have become important issues. When the requirements for heat conduction and heat dissipation are gradually severe, the market for artificial soft graphite film has solved these problems. The artificial graphite film has good conductivity, flexibility and heat transfer efficiency four times better than copper. The mobile device is used in large quantities.

The high thermal conductivity graphite film is manufactured by subjecting a high aromatic structural polymer film to a series of high temperature cracking reactions and atom rearrangement processes, which are called carbonization and graphitization. The main function of the carbonization process is thermal cracking of non-carbon elements, and the treatment temperature is between 500-1300 °C. The function of graphitization is to promote carbon atoms through high temperature, so that carbon atoms are rearranged to form a continuous ordered layered structure, which will act as a foaming phenomenon in the process, and form a foamed graphite layer structure. The temperature occurs between 2000 and 3000 °C. After the obtained foamed graphite film is subjected to a rolling treatment, a graphite film having flexibility can be obtained to be suitable for heat dissipation and electromagnetic wave shielding layers in electronic equipment.

Regardless of the multi-piece (stacked) or rolled continuous (coil) process, the carbonized film produced by the process has a problem that it is easy to cause fusion and adhesion between the film surface and the film surface. This phenomenon causes a decrease in the yield of defects or breakage on the surface of the carbonized film.

The method for producing a carbonized film of the present invention is characterized in that the average temperature rising rate of the polyimide film precursor of the carbonized film in the heating range of 500 to 800 ° C is 2 ° C or less per minute, and the highest carbonization temperature is 1000 ° C or higher. temperature.

The carbonized film produced according to the present invention can reduce the characteristics of sticking and welding between the film and the film, and obtain a carbonized film of better quality.

The method for producing a graphite film according to the present invention is characterized in that the carbonization film is subjected to heat treatment, and the average temperature rise rate at 2200 ° C to the highest graphitization temperature is less than 3 ° C per minute, and the highest carbonization temperature is 2500 ° C or higher.

Figure 1 shows the case where the carbonized film is stuck.

Figure 2 shows a good carbonized film.

Figure 3 shows the adhesion of the graphite film.

Figure 4 shows the case where the graphite film is corrugated.

Figure 5 is a good graphite film.

The graphite film produced by the present invention is produced by a thermal decomposition method of a polymer, and the production process includes carbonization and graphitization.

The carbonized film is obtained by subjecting the polyimide to a reduced pressure or an inert gas atmosphere under reduced pressure and simultaneously introducing an inert gas. The heat treatment for the carbonization step must have a maximum temperature of at least 1000 ° C, preferably 1100 ° C or higher, more preferably 1200 ° C or higher.

Graphite film: The above carbonized film is subjected to a reduced pressure or an inert gas. The heat treatment at the graphitization step has a maximum temperature of 2,400 ° C or more, preferably 2,600 ° C or more, more preferably 2,800 ° C or more. A graphite film having a high thermal diffusivity can be obtained at 2800 ° C or higher.

The film placement method of the carbonization and graphitization process of the present invention is not particularly limited. For example, the polyimide film is cut into a sheet shape, and a single piece or a plurality of pieces are stacked one on another, and then stacked by a graphite spacer. The layers of the quinone imine are heat treated after being separated; for example, the polyimide is heat-treated with a roll film having a length of more than 5 meters.

The heating device and the method to be used in the present invention are not particularly limited, and for example, a high-temperature furnace using a resistance type or a coil induction type heater. Another example is the Acheson method.

The fusion and adhesion between the carbonized film faces is due to the high temperature cracking of the lysate of the polyimide film during carbonization, which is also called tar, which cannot be smoothly discharged between the film and the film. Further, when the residual tar is carbonized after the heat treatment, sticking occurs, as shown in Fig. 1 .

The corrugations or wrinkles of the graphite film surface are caused by the simultaneous cracking of the polyimide film during the carbonization process, and the film is corrugated when the film has uneven shrinkage due to uneven heating. In the graphitization process, the carbonized film is graphitized at 2000 ° C to the highest temperature, and when the carbon structure is changed from SP ³ to SP ² , the film surface direction expands, and when the film is unevenly heated, uneven expansion occurs, or Without sufficient expansion time, wrinkles or ripples may be generated on the film surface, as shown in Fig. 4, or sticking, as shown in Fig. 3.

The method for producing a carbonized film of the present invention is characterized in that the average temperature rising rate of the polyimide film precursor of the carbonized film in the heating range of 500 to 800 ° C is 2 ° C or less per minute, and the highest carbonization temperature is 1000 ° C or higher. A preferred carbonized film 12 can be obtained as shown in FIG.

Judging criteria for adhesion: A: no sticking; B: sticking at 1~3; C: sticking at more than 3

Judging criteria for membrane surface corrugation: A: no corrugation: B: corrugation area less than 10%; C: corrugation area greater than 10%

Example 1

A flake graphite film was prepared.

<Example 1> Sheet carbonized film preparation

Polyimide (Model: TH5) produced by Damai Technology was used as a precursor, and it was sliced into a length and width of 323 mm and 323 mm, respectively, with 5 layers of polyimide film as a layer, and 0.25 layer between layers. Mm graphite spacer paper is separated. The temperature is raised under a reduced pressure atmosphere, and the rate of temperature rise is divided into the following sections: room temperature to 500 ° C is 5 ° C per minute, 500 to 800 ° C is 2 ° C per minute, and 800 to carbonization section is the highest temperature of 2 ° C per minute.

Sheet graphite film preparation

The carbonized film is graphitized by heating under normal pressure and under argon gas at a heating rate of 10 ° C per minute from room temperature to 2000 ° C, 5 ° C per minute from 2000 to 2200 ° C, and 3 ° C per minute above 2200 ° C. °C, the highest temperature of graphitization is 2850 ° C and constant temperature for 1 hour.

Example 2

The procedure of Example 1 was repeated except that the carbonization heating rate was 500 to 80 ° C at 1 ° C per minute.

Example 3

The procedure of Example 1 was repeated except that the carbonization heating rate was 500 to 800 ° C of 0.5 ° C per minute.

Example 4

The procedure of Example 1 was repeated except that the carbonization heating rate was 500 to 800 ° C of 0.25 ° C per minute.

Example 5

The procedure of Example 3 was repeated except that the graphitization heating rate was 2200 ° C or higher and 2 ° C per minute.

Example 6

The procedure of Example 3 was repeated except that the graphitization heating rate was 2200 ° C or more and was 1 ° C per minute.

Example 7

The procedure of Example 6 was repeated except that the carbonization heating rate was 500 to 800 ° C of 0.25 ° C per minute.

Example 8

The procedure of Example 7 was repeated except that the maximum temperature of carbonization was 1200 °C.

Example 9

The procedure of Example 7 was repeated except that the highest temperature of carbonization was 1000 °C.

Example 10

The procedure of Example 6 was repeated except that the maximum temperature of carbonization was 1200 °C.

Example 11

The procedure of Example 10 was repeated using a polyimide film having a thickness of 38 μm.

Example 12

The procedure of Example 10 was repeated using a polyimide micronimide film having a thickness of 62 μm, except that the highest temperature for graphitization was 2,750 °C.

Example 13

The procedure of Example 10 was repeated using a polyimide film having a thickness of 75 μm, except that the highest temperature for graphitization was 2700 °C.

Comparative example 1

The procedure of Example 1 was repeated except that the carbonization heating rate was 500 to 800 ° C of 3 ° C per minute.

Comparative example 2

The procedure of Example 3 was repeated except that the graphitization heating rate was 2200 or more and ° C was 4 ° C per minute.

Comparative example 3

The procedure of Example 7 was repeated except that the highest temperature of carbonization was 900 °C.

Example 14

Preparation of rolled graphite film

<Example 14> Rolled carbonization film preparation

A polytheneimine (model: TH5) produced by Damai Technology was used as a precursor, and a graphite film having a width of 257 mm and a length of 100 M was wound around a die having an inner diameter of 76.2 mm. The temperature is raised under a reduced pressure atmosphere, and the rate of temperature rise is divided into the following sections: room temperature to 500 ° C is 5 ° C per minute, 500 to 800 ° C is 0.5 ° C per minute, and 800 to carbonization is the highest temperature of 2 ° C per minute.

Rolled graphite film preparation

The carbonized film is graphitized by heating under normal pressure and under argon gas at a heating rate of 10 ° C per minute from room temperature to 2000 ° C, 5 ° C per minute from 2000 to 2200 ° C, and 1 per minute above 2200 ° C. °C, the highest temperature of graphitization is 2850 ° C and constant temperature for 1 hour.

Example 15

The procedure of Example 14 was repeated except that the carbonization heating rate was 500 to 800 ° C at 1 ° C per minute.

Example 16

The procedure of Example 14 was repeated except that the carbonization heating rate was 500 to 800 ° C of 2 ° C per minute.

Example 17

The procedure of Example 15 was repeated except that the graphitization heating rate was 2200 ° C or higher and 2 ° C per minute.

Comparative example 4

The procedure of Example 14 was repeated except that the carbonization heating rate was 500 to 800 ° C at 3 ° C per minute.

Comparative Example 5

The procedure of Example 15 was repeated except that the graphitization heating rate was 2200 ° C or more and was 3 ° C per minute.

Judging criteria for adhesion: A: no sticking; B: sticking at 1~3; C: sticking at more than 3

Corrugation criteria: A: no ripple: B: corrugation area is less than 10%; C: corrugation area is greater than 10%

Comparing Examples 1 to 4 with Comparative Example 1, the heating rate of carbonization at 500 ° C to 800 ° C was lowered from 3 ° C / min to 0.25 ° C / min, and the adhesion was raised from C to A. The amine membrane is sufficiently cleaved and sufficient time to drain the tar.

Comparing Examples 5 to 6 with Comparative Example 2, the temperature rising rate of graphitization from 2200 ° C to the highest temperature of graphitization was lowered from 4 ° C / min to 1 ° C / min, and the graphite film corrugation was raised from C to A. Graphitization is achieved due to sufficient heat energy.

Comparing Examples 7 to 9 with Comparative Example 3, as the maximum temperature of carbonization is increased, the pyrolyzate can be completely cleaved to obtain a high-quality carbonized film, as shown in Fig. 2, and graphitized. After that, a graphite film having high heat diffusibility is obtained, as shown in Fig. 5 .

Examples 10 to 13 are graphitized films of different thickness polyimine films, and graphite films having good appearance and high thermal diffusion properties were obtained.

Comparing Examples 14 to 16 with Comparative Example 4, the heating rate of carbonization at 500 ° C to 800 ° C was lowered from 3 ° C / min to 0.5 ° C / min, and the adhesion was raised from C to A due to the roll-like polymerization. The ruthenium imide membrane is sufficiently cleaved and sufficient time to drain the tar.

Comparing Example 15 and Example 17 with Comparative Example 5, the temperature rise rate of graphite at 2200 ° C or higher was lowered from 3 ° C / min to 1 ° C / min, and a good film surface state was obtained at 2 ° C / min, 1 ° C / Min has better thermal diffusion properties due to more sufficient heating.

The above description of the specific embodiments is intended to be illustrative of the invention, and is not intended to limit the invention. It will be understood by those skilled in the art that various changes or modifications may be made to the present invention without departing from the scope of the appended claims.

10‧‧‧ ripple

12‧‧‧Carbon film

14‧‧‧ Sticky

16‧‧‧ ripple

18‧‧‧ graphite film

Claims (5)

 A method for producing a carbonized film, comprising the steps of: providing a polyimide film as a precursor; and performing carbonization heat treatment on the polyimide film at an average temperature rising rate in a heating range of 500 to 800 ° C for each carbonization heat treatment The temperature below 2 ° C, the highest carbonization temperature is above 1000 ° C.    The method for producing a carbonized film according to the first aspect of the invention is preferably an average temperature increase rate of 1 ° C or less per minute in a heating range of 500 to 800 ° C in the carbonization heat treatment.    The method for producing a carbonized film according to claim 1, wherein the average temperature increase rate in the heating period of the carbonization heat treatment at 500 to 800 ° C is preferably 0.5 ° C or less per minute.    The method for producing a carbonized film according to the above aspect of the invention, wherein the polyimine film is in the form of a stack or a roll.    The method for producing a carbonized film according to claim 1, wherein the highest carbonization temperature is preferably 1300 °C.