A polytetrafluoroethylene vacuum bag film, a preparation method and application thereof

Abstract

The application belongs to the technical field of polymer films, and relates to a polytetrafluoroethylene vacuum bag film and a preparation method and application thereof. The preparation method comprises the following steps: first, turning a polytetrafluoroethylene rod blank to obtain a polytetrafluoroethylene turned film; then, adopting a hot roller to roll the obtained polytetrafluoroethylene turned film at 320-420 DEG C to obtain a polytetrafluoroethylene rolled film; finally, contacting one side of the obtained polytetrafluoroethylene rolled film with a sodium-naphthalene tetrahydrofuran treatment solution with a molar concentration of 0.2-0.8 mol / L for not less than 30 s to obtain the polytetrafluoroethylene vacuum bag film. The polytetrafluoroethylene vacuum bag film prepared by the above preparation method has a smooth and flat film surface and no obvious wrinkles, one side can keep the original non-stickiness and excellent demolding characteristics of polytetrafluoroethylene, and the other side has good surface adhesion, can be reliably bonded with a sealing rubber strip or a mold frame, and is suitable for a composite material forming process.

Description

Technical Field

[0001] This invention belongs to the field of polymer film technology, and relates to a polytetrafluoroethylene vacuum bag film, its preparation method and application. Background Technology

[0002] In composite material vacuum bag compression molding and autoclave molding processes, the quality of the vacuum bag directly affects the structural integrity and surface finish of the final component. Composite material curing processes in the aerospace field typically require materials to withstand temperatures exceeding 200°C, with some processes even reaching above 280°C. Under these conditions, most traditional vacuum bag films will degrade, shrink, or lose critical properties. Polytetrafluoroethylene (PTFE), due to its excellent high-temperature resistance (melting point up to 326°C), chemical inertness, and non-stick properties, has become the ideal choice for vacuum bag materials in aerospace and high-end industrial composite material molding processes.

[0003] In the existing technology, the main method for preparing dense, non-porous pure PTFE films is to cut PTFE sintered blanks into films using a special lathe, which has the advantages of simple process and high production efficiency. However, the existing turning method for PTFE films has the following technical problems: (1) During the turning process, factors such as tool vibration and material plastic deformation can easily lead to microscopic unevenness and uneven thickness on the film surface; (2) Even after annealing, the turned film may still have problems such as local wrinkles and "kelp edge" curling deformation; (3) The turned polytetrafluoroethylene film has poor sealing performance and poor barrier properties (oxygen permeability is about 8000 cm⁻¹). 3 / (m 2 ·24 h×0.1 MPa)), which cannot meet the sealing requirements of high temperature vacuum bag film; (4) Due to its extremely low surface energy and chemical inertness, PTFE is difficult to reliably bond with mold frame or sealing strip through conventional adhesives, which seriously limits its application in vacuum bag sealing structure.

[0004] Currently, existing literature reports the use of sodium-naphthalene treatment solutions to modify the surface of PTFE films, altering the surface chemical composition through chemical etching to improve their hydrophilicity and adhesion properties. However, the integration of machining, high-temperature hot roller compaction, and single-sided sodium-naphthalene treatment into the preparation of vacuum bags has not yet been reported in this field.

[0005] Therefore, there is an urgent need to develop a method for preparing polytetrafluoroethylene vacuum bag films that can take into account the uniformity, flatness, and single-sided adhesiveness of the film surface. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a polytetrafluoroethylene (PTFE) vacuum bag film, its preparation method, and its application. The PTFE vacuum bag film prepared by the method has a smooth and flat surface without obvious wrinkles. One side retains the original non-adhesiveness and excellent mold release properties of PTFE, while the other side has good surface adhesion capabilities, enabling reliable bonding with sealing strips or mold frames. It is suitable for composite material molding processes.

[0007] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a polytetrafluoroethylene vacuum bag film, the method comprising the following steps: (1) The polytetrafluoroethylene rod blank is machined to obtain a polytetrafluoroethylene machined film; (2) The polytetrafluoroethylene machined film obtained in step (1) is subjected to roll pressing at 320~420℃ (e.g., 320℃, 340℃, 360℃, 380℃, 400℃ or 420℃, etc.) using hot rollers to obtain a polytetrafluoroethylene roll-pressed film. (3) One side of the polytetrafluoroethylene roll-pressed film obtained in step (2) is contacted with a sodium-naphthalenetetrahydrofuran treatment solution with a molar concentration of 0.2~0.8 mol / L (e.g. 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, 0.55 mol / L, 0.6 mol / L, 0.7 mol / L or 0.8 mol / L, etc.) for no less than 30 s (e.g. 30 s, 60 s, 90 s, 120 s, 150 s, 200 s, 250 s, 300 s, 350 s, 400 s, 450 s, 500 s, 550 s or 600 s, etc.) to obtain the polytetrafluoroethylene vacuum bag film.

[0008] The preparation method provided by this invention first involves turning a polytetrafluoroethylene (PTFE) rod blank to obtain a PTFE-machined film. Then, the obtained PTFE-machined film is subjected to roll pressing treatment using hot rollers, with the rolling temperature controlled at 320-420°C, to obtain a PTFE-rolled film. This roll pressing process causes the surface of the PTFE-machined film to enter a micro-melting state. After the film surface micro-melts, it flows and re-solidifies under the pressure of the hot rollers, thereby eliminating machining marks and microscopic unevenness, significantly improving the uniformity and smoothness of the film surface. After hot roller pressing treatment, the film changes from an opaque white after machining to a translucent crystal color, indicating a significant improvement in film density and uniformity. Finally, one side of the obtained PTFE-rolled film is coated with a film with a molar concentration of 0.2-0.8... The sodium-naphthalene tetrahydrofuran treatment solution is applied for at least 30 seconds to perform sodium-naphthalene chemical modification treatment. The chemical composition of the film surface is changed by chemical etching, which improves the hydrophilicity and adhesion of one side of the surface, while the other side of the surface retains the original non-stickiness and excellent mold release properties of polytetrafluoroethylene.

[0009] In summary, the polytetrafluoroethylene vacuum bag film obtained by the preparation method provided by this invention has a smooth and flat surface without obvious wrinkles. One side retains the original non-stickiness and excellent mold release properties of polytetrafluoroethylene, while the other side has good surface adhesion, enabling reliable bonding with sealing strips or mold frames. This makes it suitable for composite material molding processes. Preferably, the polytetrafluoroethylene rod blank in step (1) is obtained by sieving, molding, and sintering polytetrafluoroethylene resin powder.

[0010] Preferably, the polytetrafluoroethylene resin powder is a suspension polymerized polytetrafluoroethylene resin powder.

[0011] In this invention, the suspension polymerized polytetrafluoroethylene resin powder can be selected from grades such as JF-4TM, JF-4TN-S, DF-16A, and CGM-16F.

[0012] Preferably, the sintering temperature is 370~380℃, such as 370℃, 371℃, 372℃, 373℃, 374℃, 375℃, 376℃, 377℃, 378℃, 379℃ or 380℃.

[0013] Preferably, the sintering time is 4 to 12 hours, such as 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12 hours.

[0014] In this invention, further limiting the sintering temperature and time within the above-mentioned range ensures that the obtained polytetrafluoroethylene rod blank is fully sintered and free of internal defects.

[0015] Preferably, the length of the polytetrafluoroethylene rod blank is 1~2 m, such as 1 m, 1.1 m, 1.2 m, 1.3 m, 1.4 m, 1.5 m, 1.6 m, 1.7 m, 1.8 m, 1.9 m or 2 m.

[0016] Preferably, the turning temperature in step (1) is 22~25℃, such as 22℃, 22.5℃, 23℃, 23.5℃, 24℃, 24.5℃ or 25℃.

[0017] Preferably, the thickness of the polytetrafluoroethylene machined film in step (1) is 50~200 μm, such as 50 μm, 70 μm, 90 μm, 110 μm, 130 μm, 150 μm, 170 μm, 190 μm or 200 μm.

[0018] Preferably, the spindle speed and feed motion of the tool used for turning in step (1) are controlled by a CNC system, and a constant tension winding system is used to wind the turning film to prevent stretching deformation during the winding process.

[0019] Preferably, the pressure of the roller pressing process in step (2) is 0.1~0.5 MPa, such as 0.1 MPa, 0.15 MPa, 0.2 MPa, 0.25 MPa, 0.3 MPa, 0.35 MPa, 0.4 MPa, 0.45 MPa or 0.5 MPa.

[0020] Preferably, during the rolling process in step (2), the polytetrafluoroethylene machined film passes through the hot roller at a speed of 0.5~5 m / min (e.g., 0.5 m / min, 1 m / min, 1.5 m / min, 2 m / min, 2.5 m / min, 3 m / min, 3.5 m / min, 4 m / min, 4.5 m / min or 5 m / min, etc.).

[0021] In this invention, the obtained polytetrafluoroethylene machined film is subjected to roll pressing by a hot roller device, which is equipped with one or more pairs of heating rollers, and the interior of the heating rollers is heated by an electric heating tube or a heat transfer oil medium.

[0022] Preferably, step (2) further includes a step of cooling and shaping the polytetrafluoroethylene roll-pressed film using a cooling roller after the roll pressing process.

[0023] In this invention, the roll forming process is further defined as including a cooling and shaping step using a cooling roller to achieve rapid cooling and prevent the film from sticking and deforming during winding.

[0024] Preferably, the contact method in step (3) is single-sided coating or single-sided impregnation.

[0025] Preferably, the contact temperature in step (3) is 20~40℃, such as 20℃, 22℃, 24℃, 26℃, 28℃, 30℃, 32℃, 34℃, 36℃, 38℃ or 40℃.

[0026] Preferably, the contact time in step (3) is 30~600 s, such as 30 s, 60 s, 90 s, 120 s, 150 s, 200 s, 250 s, 300 s, 350 s, 400 s, 450 s, 500 s, 550 s or 600 s, etc.

[0027] In this invention, the molar ratio of sodium to naphthalene in the sodium-naphthalene tetrahydrofuran treatment solution in step (3) is 1:1.

[0028] Preferably, step (3) further includes a cleaning and drying step after contact.

[0029] In this invention, the cleaning process can remove residual sodium-naphthalenetetrahydrofuran treatment solution from the surface.

[0030] In a second aspect, the present invention provides a polytetrafluoroethylene vacuum bag film, which is prepared by the preparation method described in the first aspect.

[0031] Preferably, the thickness of the polytetrafluoroethylene vacuum bag film is 50~200 μm, such as 50 μm, 70 μm, 90 μm, 110 μm, 130 μm, 150 μm, 170 μm, 190 μm or 200 μm.

[0032] Preferably, the width of the polytetrafluoroethylene vacuum bag film is 1~2 m, such as 1 m, 1.1 m, 1.2 m, 1.3 m, 1.4 m, 1.5 m, 1.6 m, 1.7 m, 1.8 m, 1.9 m or 2 m.

[0033] Thirdly, the present invention provides an application of polytetrafluoroethylene vacuum bag film as described in the first aspect in composite material molding processes.

[0034] Preferably, the composite material molding process includes any one of composite material vacuum bag molding, composite material autoclave molding, or composite material isobaric molding.

[0035] Specifically, the polytetrafluoroethylene vacuum bag film can be used in the manufacture of aerospace composite components such as carbon fiber reinforced wing spars, tail fins, and nose cone parts.

[0036] Compared with the prior art, the present invention has the following beneficial effects: The polytetrafluoroethylene vacuum bag film prepared by the method provided in this invention has a smooth and flat surface without obvious wrinkles, good density, and an oxygen permeability not exceeding 153 cm⁻¹. 3 / (m 2 With a strength of 24 h × 0.1 MPa, it retains the original non-stickiness and excellent mold release properties of PTFE on one side, while having good surface adhesion on the other. It can reliably bond with sealing strips or mold frames, and is suitable for composite material vacuum bag compression molding, autoclave molding and isobaric molding processes. It can be used in the manufacture of aerospace composite material components (such as carbon fiber reinforced wing spars, tail fins and nose parts). The maximum operating temperature can reach 326°C, and it can maintain excellent vacuum sealing and mold release properties in high-temperature curing processes. Attached Figure Description

[0037] Figure 1 This is a photograph of the polytetrafluoroethylene machined film obtained in step (2) of Example 1; Figure 2 This is a photograph of the polytetrafluoroethylene vacuum bag film obtained in Example 1. Detailed Implementation

[0038] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0039] Example 1 A method for preparing a polytetrafluoroethylene vacuum bag film specifically includes the following steps: (1) Preparation of PTFE rod blank: Suspension polymerized PTFE resin powder (brand name JF-4TM) was selected, sieved through a three-layer combination sieve of 20 / 60 / 20 mesh, then molded at 0.25 MPa, and finally sintered at 375℃ for 10 h to obtain PTFE rod blank with a length of 2 m. (2) Turning and forming: The PTFE rod blank obtained in step (1) is mounted on a high-precision CNC lathe, the turning environment temperature is controlled at 24°C, and the rotating blank is continuously turned by a precision turning tool. The spindle speed and feed motion of the turning tool are controlled by the CNC system. A constant tension winding system is used to wind the film to obtain a polytetrafluoroethylene turning film with a thickness of 150 μm. (3) Rolling treatment: The polytetrafluoroethylene machined film obtained in step (2) is passed through a high-temperature hot roller device. The device is equipped with a pair of hot rollers. The inside of the rollers is heated by electric heating tubes. The surface temperature of the hot rollers is controlled at 350°C and the pressure between the rollers is 0.25 MPa. The PTFE machined film passes through the hot rollers at a speed of 1 m / min and then passes through the cooling rollers at a speed of 1 m / min. The surface temperature of the cooling rollers is 150°C, thus obtaining a polytetrafluoroethylene roll-pressed film. (4) Sodium-naphthalene chemical modification treatment: one side of the obtained polytetrafluoroethylene roll-pressed film is immersed in sodium-naphthalene tetrahydrofuran treatment solution (sodium molar concentration is 0.4 mol / L, sodium and naphthalene molar ratio is 1:1) for 5 min at a temperature of 35°C. After immersion, the film surface is thoroughly cleaned with deionized water and dried to obtain the polytetrafluoroethylene vacuum bag film.

[0040] Appearance: The actual image of the polytetrafluoroethylene machined film obtained by step (2) of the preparation method provided in Example 1 is shown below. Figure 1 As shown in the image, the final physical image of the polytetrafluoroethylene vacuum bag film is as follows. Figure 2 As shown; comparison Figure 1 and Figure 2 It can be seen that the PTFE machined film after machining is opaque white, and the PTFE vacuum bag film obtained after hot roller pressing is translucent crystal color, indicating that the density and uniformity of the film surface have been significantly improved.

[0041] Example 2 A method for preparing a polytetrafluoroethylene vacuum bag film specifically includes the following steps: (1) Preparation of PTFE rod blank: Suspension polymerized PTFE resin powder (brand name JF-4TN) was selected, sieved through a three-layer combination sieve of 20 / 60 / 20 mesh, then molded at 0.25 MPa, and finally sintered at 380℃ for 5 h to obtain PTFE rod blank with a length of 1.5 m. (2) Turning and forming: The PTFE rod blank obtained in step (1) is installed on a high-precision CNC lathe. The turning environment temperature is controlled at 23°C. The rotating blank is continuously turned by a precision turning tool. The spindle speed and feed motion of the turning tool are controlled by the CNC system. The film is wound by a constant tension winding system to obtain a polytetrafluoroethylene turning film with a thickness of 60 μm. (3) Rolling treatment: The polytetrafluoroethylene machined film obtained in step (2) is passed through a high-temperature hot roller device. The device is equipped with two pairs of hot rollers. The inside of the two pairs of hot rollers is heated by electric heating tubes. The surface temperature of the two pairs of hot rollers is controlled at 325°C. The pressure between the rollers is 0.45 MPa. The PTFE machined film passes through the hot rollers at a speed of 0.6 m / min and then passes through the cooling rollers at a speed of 0.6 m / min. The surface temperature of the cooling rollers is 150°C, thus obtaining the polytetrafluoroethylene roll-pressed film. (4) Sodium-naphthalene chemical modification treatment: Sodium-naphthalene tetrahydrofuran treatment solution (sodium molar concentration of 0.3 mol / L, sodium and naphthalene molar ratio of 1:1) is coated on one side of the polytetrafluoroethylene roll-pressed film, and the holding time is 9 min at a temperature of 25°C. After the treatment, the film surface is thoroughly cleaned with deionized water and dried to obtain the polytetrafluoroethylene vacuum bag film.

[0042] Example 3 A method for preparing a polytetrafluoroethylene vacuum bag film specifically includes the following steps: (1) Preparation of PTFE rod blank: Suspension polymerized PTFE resin powder (brand name DF-16A) was selected, sieved through a three-layer combination sieve of 20 / 60 / 20 mesh, then molded at 0.25 MPa, and finally sintered at 370℃ for 11 h to obtain PTFE rod blank with a length of 1 m. (2) Turning and forming: The PTFE rod blank obtained in step (1) is installed on a high-precision CNC lathe. The turning environment temperature is controlled at 25°C. The rotating blank is continuously turned by a precision turning tool. The spindle speed and feed motion of the turning tool are controlled by the CNC system. The film is wound by a constant tension winding system to obtain a polytetrafluoroethylene turning film with a thickness of 180 μm. (3) Rolling treatment: The polytetrafluoroethylene machined film obtained in step (2) is passed through a high-temperature hot roller device. The device is equipped with three pairs of hot rollers. The inside of the three pairs of hot rollers is heated by electric heating tubes. The surface temperature of the three pairs of hot rollers is controlled at 410°C and the pressure between the rollers is 0.15 MPa. The PTFE machined film passes through the three pairs of hot rollers at a speed of 4.5 m / min and then passes through a pair of cooling rollers at a speed of 4.5 m / min. The surface temperature of the cooling rollers is 150°C, thus obtaining a polytetrafluoroethylene roll-pressed film. (4) Sodium-naphthalene chemical modification treatment: One side of the obtained polytetrafluoroethylene roll-pressed film is immersed in sodium-naphthalene tetrahydrofuran treatment solution (sodium molar concentration is 0.6 mol / L, sodium and naphthalene molar ratio is 1:1) for 1 min at a temperature of 35°C. After immersion, the film surface is thoroughly cleaned with deionized water and dried to obtain the polytetrafluoroethylene vacuum bag film.

[0043] Comparative Example 1 A method for preparing a polytetrafluoroethylene vacuum bag film differs from Example 1 only in that the temperature of the hot roller surface is controlled at 300°C, while all other conditions and parameters are the same as in Example 1.

[0044] Comparative Example 2 A method for preparing a polytetrafluoroethylene vacuum bag film differs from Example 1 only in that the temperature of the hot roller surface is controlled at 450°C, while other conditions and parameters are the same as in Example 1.

[0045] Comparative Example 3 A method for preparing a polytetrafluoroethylene vacuum bag film differs from Example 1 only in that the molar concentration of sodium in the sodium-naphthalenetetrahydrofuran treatment solution is 0.1 mol / L, while all other conditions and parameters are the same as in Example 1.

[0046] Comparative Example 4 A method for preparing a polytetrafluoroethylene vacuum bag film differs from Example 1 only in that the molar concentration of sodium in the sodium-naphthalenetetrahydrofuran treatment solution is 1 mol / L, while all other conditions and parameters are the same as in Example 1.

[0047] Comparative Example 5 A method for preparing a polytetrafluoroethylene vacuum bag film, which differs from Example 1 only in that the impregnation treatment time is 25 s, while all other conditions and parameters are the same as in Example 1.

[0048] Comparative Example 6 A method for preparing a polytetrafluoroethylene vacuum bag film, which differs from Example 1 in that step (3) roll forming is not performed, while other conditions and parameters are the same as in Example 1.

[0049] Comparative Example 7 A method for preparing a polytetrafluoroethylene vacuum bag film, which differs from Example 1 in that step (4) sodium-naphthalene chemical modification is not performed, while other conditions and parameters are the same as in Example 1.

[0050] Performance testing: (1) Film appearance: Visually inspect whether the thickness of the polytetrafluoroethylene vacuum bag film is uniform, whether the film surface is flat and smooth, and whether there are obvious wrinkles.

[0051] (2) Oxygen permeability: Tested according to the method provided in GB / T 19789-2021.

[0052] (3) Adhesion: Under the condition that the peel force between the PTFE vacuum bag film and the sealing tape is 3 N / cm, the test shows that the sealing tape has good adhesion and the two cannot be torn apart. After being placed at room temperature for 7 days, the adhesion of the sealing tape is almost unchanged, and the test shows that the sealing tape has good adhesion and the two cannot be torn apart. After being placed at 300℃ for 6 hours, the adhesion of the sealing tape is almost unchanged, and the two are still difficult to tear apart. If the adhesion test is met, the adhesion test requirement is not met.

[0053] The polytetrafluoroethylene vacuum bag films obtained in Examples 1-3 and Comparative Examples 1-7 were tested according to the above test methods. The test results are shown in Table 1. Table 1

[0054] According to the data in Table 1: The polytetrafluoroethylene vacuum bag films obtained by the preparation methods provided in Examples 1-3 have a uniform, smooth, and wrinkle-free surface, and an oxygen permeability not exceeding 153 cm⁻¹. 3 / (m 2 It has a strength of 24 h × 0.1 MPa and one side has good surface adhesion.

[0055] The low temperature of the rolling process in the preparation method provided in Comparative Example 1 and the absence of rolling process in the preparation method provided in Comparative Example 6 both resulted in the inability to form a micro-melting state on the membrane surface, thus failing to eliminate machining marks and micro-unevenness. Consequently, the membrane surface had poor flatness and could not seal the pores, leading to a high oxygen permeability.

[0056] The preparation method provided in Comparative Example 2 uses a high temperature for the rolling process, which easily causes the film surface to soften and is prone to breakage under tension, making it difficult to process and form.

[0057] The sodium molar concentration in the sodium-naphthalenetetrahydrofuran treatment solution in the preparation method provided in Comparative Example 3 was too low, the impregnation treatment time in the preparation method provided in Comparative Example 5 was too short, and Comparative Example 7 did not perform impregnation treatment at all. All of these resulted in poor modification degree, poor adhesion of the obtained polytetrafluoroethylene vacuum bag film, and difficulty in changing the original non-stick surface characteristics of the polytetrafluoroethylene vacuum bag film.

[0058] In the preparation method provided in Comparative Example 4, the molar concentration of sodium in the sodium-naphthalenetetrahydrofuran treatment solution is too high, which can easily cause membrane perforation and make it difficult to use.

[0059] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a polytetrafluoroethylene vacuum bag film, characterized in that, The preparation method includes the following steps: (1) The polytetrafluoroethylene rod blank is machined to obtain a polytetrafluoroethylene machined film; (2) The polytetrafluoroethylene machined film obtained in step (1) is subjected to roll pressing at 320~420℃ using hot rollers to obtain a polytetrafluoroethylene roll-pressed film; (3) Contact one side surface of the polytetrafluoroethylene roll-pressed film obtained in step (2) with a sodium-naphthalenetetrahydrofuran treatment solution with a molar concentration of 0.2~0.8 mol / L for no less than 30 s to obtain the polytetrafluoroethylene vacuum bag film.

2. The preparation method according to claim 1, characterized in that, The polytetrafluoroethylene rod blank in step (1) is obtained by sieving, molding and sintering polytetrafluoroethylene resin powder.

3. The preparation method according to claim 1, characterized in that, The turning temperature in step (1) is 22~25℃.

4. The preparation method according to claim 1, characterized in that, The pressure of the roller pressing process in step (2) is 0.1~0.5 MPa.

5. The preparation method according to claim 1, characterized in that, Step (2) after the roll forming process also includes a step of cooling and shaping the polytetrafluoroethylene roll-formed film using a cooling roller.

6. The preparation method according to claim 1, characterized in that, The contact method described in step (3) is single-sided coating or single-sided impregnation.

7. The preparation method according to claim 1, characterized in that, The contact time in step (3) is 30~600 s.

8. A polytetrafluoroethylene vacuum bag film, characterized in that, The polytetrafluoroethylene vacuum bag film is prepared by the preparation method described in any one of claims 1 to 7.

9. The polytetrafluoroethylene vacuum bag film according to claim 8, characterized in that, The thickness of the polytetrafluoroethylene vacuum bag film is 50~200 μm.

10. The application of a polytetrafluoroethylene vacuum bag film as described in claim 8 or 9 in a composite material molding process.

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