Expanded polytetrafluoroethylene sealing material, preparation method thereof and aerospace covering cap structure

Abstract

The invention relates to the technical field of sealing materials, in particular to an expanded polytetrafluoroethylene sealing material, a preparation method thereof and an aerospace covering cap structure. The preparation method of the expanded polytetrafluoroethylene sealing material comprises the following steps: sequentially coiling a first expanded polytetrafluoroethylene film with the thickness of 0.01-0.03 mm, a second expanded polytetrafluoroethylene film with the thickness of 0.06-0.12 mm and a third expanded polytetrafluoroethylene film with the thickness of 0.01-0.03 mm onto a roller; the expanded polytetrafluoroethylene film coated on the roller is laminated while the expanded polytetrafluoroethylene film is rolled up to the roller; after coiling is completed, laminating and sintering are continued, and the expanded polytetrafluoroethylene sealing material is obtained; wherein the pressure of the lamination is 0.2 to 0.3 MPa. According to the preparation method, high strength and stability of the expanded polytetrafluoroethylene sealing material are guaranteed, and meanwhile, the sealing performance, the flexibility and the wear resistance are improved.

Description

Technical Field

[0001] The invention relates to the technical field of sealing materials, in particular to an expanded polytetrafluoroethylene sealing material and a preparation method thereof, and an aerospace cover structure. Background Art

[0002] In the complex design and precise construction of aerospace vehicles, in order to meet diverse functional requirements, engineers have to cleverly set various openings on the fuselage. The structural frame around these openings is called the opening frame. The opening frame is not only a simple opening boundary, but also a bridge connecting the inside of the aerospace vehicle with the outside world, carrying important functional and structural tasks.

[0003] In aerospace equipment, the flap structure is a key component to maintain the sealing of the internal environment. In order to maintain the sealing and safety of aerospace equipment, firstly, the flap must have good sealing performance to prevent dust and moisture from the external environment from entering the cabin. Secondly, the flap should have a certain strength and rigidity to withstand various mechanical effects during flight.

[0004] Traditional sealing materials often have problems such as poor sealing effect and easy wear when dealing with complex and changeable flight environments and small gaps. As a high-performance sealing material, expanded polytetrafluoroethylene material has good corrosion resistance and high temperature resistance. However, under extreme working conditions, especially in the aerospace field, the flap needs to withstand large pressure differences and temperature changes, and its sealing durability may be affected. It may not be enough to meet the sealing requirements under extreme conditions, and may not be able to completely prevent small leakage of gas or liquid. During the manufacturing process, the shape and size of the material need to be precisely controlled to ensure the reliability of the seal, but the processing performance of expanded polytetrafluoroethylene material is poor. Expanded polytetrafluoroethylene material is generally soft or hard, and it is difficult to adapt to the complex and changeable flap structure. During the opening and closing process of the flap, the expanded polytetrafluoroethylene material may be damaged due to friction and extrusion. Frequent friction and wear will shorten the service life of the flap and the mouth frame and increase maintenance costs. In an environment of high pressure, high speed or frequent movement, expanded polytetrafluoroethylene material may still produce significant wear. The accumulation of friction and wear will lead to a decrease in sealing performance and even cause failures.

[0005] In view of this, this invention is proposed. Summary of the invention

[0006] The first object of the present invention is to provide a method for preparing an expanded polytetrafluoroethylene sealing material, which improves the sealing performance, softness and wear resistance of the expanded polytetrafluoroethylene sealing material while ensuring the high strength and stability of the expanded polytetrafluoroethylene sealing material.

[0007] The second object of the present invention is to provide an expanded polytetrafluoroethylene sealing material, which has an excellent sealing effect, can effectively prevent the leakage of gas or liquid, and reduce friction and wear.

[0008] The third purpose of the present invention is to provide an aerospace cover structure, which improves the sealing effect of the cover, reduces friction and wear, and prolongs the service life.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0010] In a first aspect, the present invention provides a method for preparing an expanded polytetrafluoroethylene sealing material, comprising the following steps:

[0011] The first expanded polytetrafluoroethylene film, the second expanded polytetrafluoroethylene film and the third expanded polytetrafluoroethylene film are rolled up onto a roller in sequence, and the expanded polytetrafluoroethylene film coated on the roller is laminated while being rolled up onto the roller; after the rolling is completed, the lamination is continued, and after sintering, the expanded polytetrafluoroethylene sealing material is obtained;

[0012] The thickness of the first expanded polytetrafluoroethylene film is 0.01-0.03 mm, the thickness of the second expanded polytetrafluoroethylene film is 0.06-0.12 mm, the thickness of the third expanded polytetrafluoroethylene film is 0.01-0.03 mm, and the lamination pressure is 0.2-0.3 MPa.

[0013] Furthermore, the rolled-up thickness of the first expanded polytetrafluoroethylene film is 0.55 to 0.65 mm.

[0014] Furthermore, the rolled-up thickness of the second expanded polytetrafluoroethylene film is 1.2-1.3 mm.

[0015] Furthermore, the rolled-up thickness of the third expanded polytetrafluoroethylene film is 0.55 to 0.65 mm.

[0016] Furthermore, the rotation speed of the roller is 2 to 6 m / min.

[0017] Furthermore, after the rolling is completed, lamination is continued for 2 to 5 minutes.

[0018] Furthermore, the sintering includes: heat preservation treatment at 360-380° C. for 1-2 hours.

[0019] Furthermore, the preparation method of the expanded polytetrafluoroethylene sealing material comprises the following steps:

[0020] S1, rolling up the first expanded polytetrafluoroethylene film onto a roller, and performing a first lamination on the expanded polytetrafluoroethylene film coated on the roller to obtain a roller A coated with the film;

[0021] S2, rolling the second expanded polytetrafluoroethylene film onto the film-coated roller A, and performing a second lamination on the expanded polytetrafluoroethylene film coated on the roller to obtain a film-coated roller B;

[0022] S3, rolling the third expanded polytetrafluoroethylene film onto the roller B coated with the film, and performing a third lamination on the expanded polytetrafluoroethylene film coated on the roller to obtain a roller C coated with the film;

[0023] S4, performing a fourth lamination and sintering on the roller C coated with the film to obtain the expanded polytetrafluoroethylene sealing material.

[0024] In a second aspect, the present invention further provides an expanded polytetrafluoroethylene sealing material, which is prepared by the method for preparing the expanded polytetrafluoroethylene sealing material as described above.

[0025] In a third aspect, the present invention further provides an aerospace cover structure, which is made of the expanded polytetrafluoroethylene sealing material as described above.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The preparation method of the expanded polytetrafluoroethylene sealing material of the present invention can make the expanded polytetrafluoroethylene sealing material more balanced in overall performance by improving the thickness of each layer and the preparation process, and improve the sealing performance, softness, wear resistance, aging resistance, corrosion resistance, etc. while ensuring high strength and stability.

[0028] 2. The expanded polytetrafluoroethylene sealing material of the present invention has a three-layer structure. The middle layer can provide high strength and stability, and the surface layers on both sides can provide better sealing and softness. The layers are tightly combined, and the functional characteristics of different layers are complementary to each other to achieve an improvement in the overall performance. While maintaining the overall strength, better sealing performance and flexibility can be achieved.

[0029] 3. The aerospace cover structure made of the expanded polytetrafluoroethylene sealing material of the present invention can withstand large pressure differences and temperature changes; can adapt to complex and changeable cover structures; can better fill the small gap between the cover frame and the cover; can reduce friction and wear; and improve the sealing performance and service life of the aerospace cover structure. DETAILED DESCRIPTION

[0030] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be appreciated by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work, all belong to the scope of protection of the present invention. If specific conditions are not indicated in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0031] The following is a detailed description of an expanded polytetrafluoroethylene sealing material and a preparation method thereof and an aerospace cover structure according to an embodiment of the present invention.

[0032] In some embodiments of the present invention, a method for preparing an expanded polytetrafluoroethylene sealing material is provided, comprising the following steps:

[0033] The first expanded polytetrafluoroethylene film, the second expanded polytetrafluoroethylene film and the third expanded polytetrafluoroethylene film are rolled up onto a roller in sequence, and the expanded polytetrafluoroethylene film coated on the roller is laminated while being rolled up onto the roller; after the rolling is completed, the lamination is continued, and after sintering, an expanded polytetrafluoroethylene sealing material is obtained;

[0034] The thickness of the first expanded polytetrafluoroethylene film is 0.01-0.03 mm, the thickness of the second expanded polytetrafluoroethylene film is 0.06-0.12 mm, the thickness of the third expanded polytetrafluoroethylene film is 0.01-0.03 mm, and the lamination pressure is 0.2-0.3 MPa.

[0035] The preparation method of the expanded polytetrafluoroethylene sealing material of the present invention improves the thickness of each layer and the preparation process, so that the prepared expanded polytetrafluoroethylene sealing material forms a three-layer structure, and each layer has specific functional characteristics; the middle layer can provide high strength and stability, and the surface layers on both sides can provide more excellent sealing and softness, so that the expanded polytetrafluoroethylene sealing material is more balanced in overall performance. While ensuring overall high strength and stability, the sealing performance, softness, wear resistance, aging resistance, corrosion resistance and other aspects are all improved.

[0036] The expanded polytetrafluoroethylene film with a thickness of 0.01 to 0.03 mm is thinner and has a lower density, so the prepared expanded polytetrafluoroethylene sealing material has better softness, porosity and sealing effect; the expanded polytetrafluoroethylene film with a thickness of 0.06 to 0.12 mm is thicker, so the prepared expanded polytetrafluoroethylene sealing material has a relatively higher density, a smaller shrinkage rate, and a more stable product size; the expanded polytetrafluoroethylene sealing material prepared by using films of different thicknesses has a three-layer structure, the upper and lower layers provide better softness and sealing, and the middle layer provides better dimensional stability.

[0037] Expanded polytetrafluoroethylene itself has certain softness and elasticity. After being treated by the process of the present invention, its surface softness can be further improved, so that it can better adapt to the complex and changeable mouth cover structure and better fill the small gap between the mouth frame and the mouth cover, thereby providing an excellent sealing effect; in addition, the softer expanded polytetrafluoroethylene sealing material can reduce the damage caused by friction and extrusion, reduce the friction and wear between the sealing material and the mouth frame, thereby extending the service life of the mouth cover and the mouth frame.

[0038] The preparation method of the present invention can ensure the close bonding between the layers and the compactness of the material, can effectively prevent the leakage of gas or liquid, and improve the sealing effect.

[0039] The present invention performs lamination under a pressure of 0.2-0.3 MPa, thereby improving the peeling strength of the material, ensuring strong interlayer bonding of the sealing material, and achieving the required density of the product. When the pressure is too high, the product density is too high, and vice versa, the interlayer bonding is poor and the peeling strength is low.

[0040] In the preparation method of the present invention, lamination pressure is applied while the polytetrafluoroethylene film is rolled onto a roller, so that the films are more closely bonded, the interlayer bonding force is improved, the problems of delamination and falling off are prevented during use, and the overall strength and stability are improved.

[0041] In different embodiments of the present invention, the thickness of the first expanded polytetrafluoroethylene film may be 0.01 mm, 0.015 mm, 0.02 mm, 0.025 mm, 0.03 mm, or a range of any two thereof;

[0042] The thickness of the second expanded polytetrafluoroethylene film may be 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.1 mm, 0.11 mm, 0.12 mm or a range of any two thereof;

[0043] The thickness of the third expanded polytetrafluoroethylene film may be 0.01 mm, 0.015 mm, 0.02 mm, 0.025 mm, 0.03 mm, or a range of any two thereof;

[0044] The lamination pressure may be 0.2 MPa, 0.22 MPa, 0.24 MPa, 0.26 MPa, 0.28 MPa, 0.3 MPa or a range of any two thereof.

[0045] The rolling up of the present invention refers to: winding and coating the expanded polytetrafluoroethylene film on a roller, and the coating is completed when the coating reaches the required thickness.

[0046] In some embodiments of the present invention, the roller comprises a circular film-coated roller.

[0047] The invention adopts a circular roller, so that the expanded polytetrafluoroethylene film can be evenly and tightly coated on the roller.

[0048] In some embodiments of the present invention, the rolled-up thickness of the first expanded polytetrafluoroethylene film is 0.55-0.65 mm; typically but not limiting, for example, the rolled-up thickness of the first expanded polytetrafluoroethylene film can be 0.55 mm, 0.6 mm, 0.65 mm or a range of any two thereof.

[0049] In some embodiments of the present invention, the rolled-up thickness of the second expanded polytetrafluoroethylene film is 1.2-1.3 mm; typically but not limitatively, for example, the rolled-up thickness of the second expanded polytetrafluoroethylene film can be 1.2 mm, 1.22 mm, 1.24 mm, 1.26 mm, 1.28 mm, 1.3 mm or a range of any two thereof.

[0050] In some embodiments of the present invention, the rolled-up thickness of the third expanded polytetrafluoroethylene film is 0.55-0.65 mm; typically but not limitatively, for example, the rolled-up thickness of the third expanded polytetrafluoroethylene film can be 0.55 mm, 0.6 mm, 0.65 mm or a range of any two thereof.

[0051] The thickness of the upper roll directly affects the thickness of the prepared expanded polytetrafluoroethylene sealing material; the above three-layer structure enables the sealing material to have both excellent sealing performance and product dimensional stability. If the upper and lower layers are too thick and the middle layer is thin, it will cause serious shrinkage of the product size, otherwise it will lead to poor sealing performance.

[0052] The rolled-up thickness of the present invention refers to the thickness obtained by multiplying the thickness of one layer of expanded polytetrafluoroethylene film by the number of coated turns.

[0053] In some preferred embodiments of the present invention, the thickness of the first expanded polytetrafluoroethylene film is the same as the thickness of the third expanded polytetrafluoroethylene film; and the lamination pressure is kept consistent during the entire rolling process.

[0054] In some embodiments of the present invention, the rotation speed of the roller is 2 to 6 m / min; typically but not limitatively, for example, the rotation speed of the roller can be 2 m / min, 3 m / min, 4 m / min, 5 m / min, 6 m / min or a range of any two thereof.

[0055] In some embodiments of the present invention, after rolling is completed, lamination is continued for 2 to 5 minutes; typically but not limitatively, for example, after rolling is completed, the lamination time may be continued for 2 minutes, 3 minutes, 4 minutes, 5 minutes or a range of any two thereof.

[0056] In some embodiments of the present invention, sintering includes: heat preservation treatment at 360-380°C for 1-2h; typically but not limitatively, for example, the sintering temperature can be 360°C, 365°C, 370°C, 375°C, 380°C or a range consisting of any two thereof; the sintering time can be 1h, 1.5h, 2h or a range consisting of any two thereof.

[0057] In some embodiments of the present invention, a dispersed polytetrafluoroethylene resin is prepared into a calendered film by a paste molding method, and then biaxially stretched to prepare a first expanded polytetrafluoroethylene film, a second expanded polytetrafluoroethylene film and a third expanded polytetrafluoroethylene film of different thicknesses.

[0058] In some embodiments of the present invention, the method for preparing the expanded polytetrafluoroethylene sealing material specifically comprises the following steps:

[0059] S1, rolling a first expanded polytetrafluoroethylene film with a thickness of 0.01-0.03 mm onto a circular roller through a laminating unit, and performing a first lamination on the film coated on the roller, the roller speed is 2-6 m / min, the first lamination pressure is 0.2-3 MPa, the rolling thickness is 0.55-0.65 mm, and a roller A coated with the film is obtained;

[0060] S2, rolling up the second expanded polytetrafluoroethylene film with a thickness of 0.06-0.12 mm onto the roller A coated with the film through a laminating unit, and performing a second lamination on the film coated on the laminating roller, the roller speed is 2-6 m / min, the second lamination pressure is 0.2-0.3 MPa, the rolling thickness is 1.2-1.3 mm, and a roller B coated with the film is obtained;

[0061] S3, rolling up the third expanded polytetrafluoroethylene film with a thickness of 0.01-0.03 mm onto the roller B coated with the film through a coating unit, and performing a third lamination on the film coated on the coating roller, the roller speed is 2-6 m / min, the third lamination pressure is 0.2-0.3 MPa, the rolling thickness is 0.55-0.65 mm, and a roller C coated with the film is obtained;

[0062] S4, continuing the fourth lamination of the roller C coated with the film for 2 to 5 minutes, the rotation speed of the roller is 2 to 6 m / min, and the pressure of the fourth lamination is 0.2 to 0.3 MPa; after sintering, an expanded polytetrafluoroethylene sealing material is obtained.

[0063] In some embodiments of the present invention, an expanded polytetrafluoroethylene sealing material is also provided, which is prepared by the above-mentioned method for preparing the expanded polytetrafluoroethylene sealing material.

[0064] The expanded polytetrafluoroethylene sealing material of the present invention comprises a first film layer, a second film layer and a third film layer; the thickness ratio of the first film layer, the second film layer and the third film layer is (0.9-1.1): (1.8-2.2): (0.9-1.1).

[0065] In some embodiments of the present invention, the density of the expanded polytetrafluoroethylene sealing material is 0.6±0.05 g / cm 3 , thickness is 1.1~1.3mm.

[0066] The expanded polytetrafluoroethylene sealing material of the present invention has a three-layer structure, the second film layer is responsible for bearing most of the pressure and stress, while the first film layer and the second film layer provide additional protection and sealing effects; the overall performance is improved by complementing the functional characteristics of different layers, which helps to achieve better sealing performance and flexibility while maintaining overall strength.

[0067] The expanded polytetrafluoroethylene sealing material of the present invention has excellent surface softness, which can better adapt to the complex and changeable cover structure and reduce the damage caused by friction and extrusion.

[0068] The present invention can reduce the friction and wear between the sealing material and other materials by optimizing the surface characteristics and structure of the expanded polytetrafluoroethylene sealing material.

[0069] The expanded polytetrafluoroethylene sealing material of the present invention has layers that are tightly combined, and has good material density, which can effectively prevent gas or liquid leakage, thereby improving sealing performance.

[0070] In some embodiments of the present invention, an aerospace cover structure is also provided, which is made of the above-mentioned expanded polytetrafluoroethylene sealing material.

[0071] The aerospace cover structure made of the expanded polytetrafluoroethylene sealing material can withstand large pressure differences and temperature changes; can adapt to complex and changeable cover structures; can better fill the tiny gap between the cover frame and the cover; during the opening and closing process of the cover, it can reduce material damage caused by friction and extrusion; and improve the sealing performance and service life of the aerospace cover structure.

[0072] Example 1

[0073] The method for preparing the expanded polytetrafluoroethylene sealing material provided in this embodiment comprises the following steps:

[0074] S1. Prepare a calendered film by a paste molding method using a dispersed polytetrafluoroethylene resin, and prepare an expanded polytetrafluoroethylene film with a thickness of 0.015±0.01 mm and an expanded polytetrafluoroethylene film with a thickness of 0.09±0.02 mm by biaxial stretching;

[0075] A first expanded polytetrafluoroethylene film with a thickness of 0.015±0.01 mm is rolled up onto a circular coating roller through a coating unit, and a pressure mechanism is used to perform a first lamination on the film coated on the coating roller. The rotation speed of the coating roller is 2 m / min, the pressure of the first lamination is 0.2 MPa, and the thickness of the roll-up is 0.55-0.65 mm, thereby obtaining a coating roller A coated with the film;

[0076] S2, rolling up the second expanded polytetrafluoroethylene film with a thickness of 0.09±0.02 mm onto the film-coated film-coated roller A through a film-coating unit, and at the same time, performing a second lamination on the film coated on the film-coated roller by a pressure mechanism, the rotation speed of the film-coating roller is 2 m / min, the pressure of the second lamination is 0.2 MPa, and the rolling thickness is 1.2-1.3 mm, so as to obtain a film-coated film-coated roller B;

[0077] S3, rolling up the third expanded polytetrafluoroethylene film with a thickness of 0.015±0.01mm onto the film-coated film-coated roller B through the film-coating unit, and at the same time, performing a third lamination on the film coated on the film-coated roller by a pressure mechanism, the rotation speed of the film-coating roller is 2m / min, the third pressure is 0.2MPa, and the rolling thickness is 0.55-0.65mm, so as to obtain a film-coated film-coated roller C;

[0078] S4, the film coating roller C is subjected to the fourth lamination for 3 minutes by a pressure mechanism, the rotation speed of the coating roller is 2m / min, the pressure of the fourth lamination is 0.2MPa, the films at both ends of the coating roller are fixed, and then the roller is removed; the removed roller is placed in a sintering furnace, heat-treated at 370°C for 1 hour, the sintering box is opened and cooled to room temperature, and the roller is taken out from the sintering furnace, the obtained expanded polytetrafluoroethylene sealing material is removed from the roller, and then cut according to production requirements;

[0079] The density of expanded polytetrafluoroethylene sealing material is 0.6±0.05g / cm 3 , thickness is 1.2±0.05mm.

[0080] Example 2

[0081] The preparation method of the expanded polytetrafluoroethylene sealing material provided in this embodiment refers to Example 1, except that in step S1, the pressure of the first lamination is 0.3 MPa; in step S2, the pressure of the second lamination is 0.3 MPa; in step S3, the pressure of the third lamination is 0.3 MPa; in step S4, the pressure of the fourth lamination is 0.3 MPa; the density of the expanded polytetrafluoroethylene sealing material is 0.65±0.05 g / cm 3 , thickness is 1.15±0.05mm.

[0082] Example 3

[0083] The preparation method of the expanded polytetrafluoroethylene sealing material provided in this embodiment refers to that in embodiment 1, the only difference is that in steps S1 to S4, the rotation speed of the coating roller is 4 m / min; the density of the expanded polytetrafluoroethylene sealing material is 0.6±0.05 g / cm 3 , thickness is 1.2±0.05mm.

[0084] Comparative Example 1

[0085] The preparation method of the expanded polytetrafluoroethylene sealing material provided in this comparative example is based on Example 1, except that in step S1, the pressure of the first lamination is 0.4 MPa; in step S2, the pressure of the second lamination is 0.4 MPa; in step S3, the pressure of the third lamination is 0.4 MPa; in step S4, the pressure of the fourth lamination is 0.4 MPa; the density of the expanded polytetrafluoroethylene sealing material is 0.75±0.05 g / cm 3 , thickness is 1.1±0.1mm.

[0086] Comparative Example 2

[0087] The preparation method of the expanded polytetrafluoroethylene sealing material provided in this comparative example comprises the following steps:

[0088] S1, preparing a calendered film by a paste molding method using a dispersed polytetrafluoroethylene resin, and preparing an expanded polytetrafluoroethylene film with a thickness of 0.09±0.02 mm by biaxial stretching;

[0089] S2, rolling the expanded polytetrafluoroethylene film onto a circular coating roller through a coating unit, and laminating the film coated on the coating roller using a pressure mechanism, the rotation speed of the coating roller is 2m / min, the pressure of the pressure mechanism is 0.2MPa, the thickness of the roll is 2.3-2.6mm, and a roller coated with the film is obtained;

[0090] S3, fix the films at both ends of the coating roller, and then remove the roller; place the removed roller in a sintering furnace, keep it at 370°C for 1 hour, open the sintering box to cool it to room temperature, take it out of the sintering furnace, remove the obtained expanded polytetrafluoroethylene sealing material from the roller, and then cut it according to production requirements;

[0091] The density of expanded polytetrafluoroethylene sealing material is 0.65±0.05g / cm 3 , thickness is 1.2±0.1mm.

[0092] Comparative Example 3

[0093] The preparation method of the expanded polytetrafluoroethylene sealing material provided in this comparative example refers to comparative example 1, except that the expanded polytetrafluoroethylene film with a thickness of 0.09±0.02 mm is replaced by an expanded polytetrafluoroethylene film with a thickness of 0.015±0.01 mm; the density of the expanded polytetrafluoroethylene sealing material is 0.65±0.05 g / cm 3 , thickness is 1.2±0.1mm.

[0094] Test example

[0095] The properties of the expanded polytetrafluoroethylene sealing materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were tested, and the results are shown in Table 1.

[0096] The test method for longitudinal tensile strength is: GB / T1040.2-2006;

[0097] The test method for transverse tensile strength is: GB / T1040.2-2006;

[0098] The test method for peel strength is: GB / T2792-2014.

[0099] Table 1

[0100]

[0101]

[0102] It can be seen from Table 1 that the density of the expanded polytetrafluoroethylene sealing material of Comparative Example 1 is too high. The greater the lamination pressure, the greater the density of the material; under the same lamination pressure, the thinner the film, the lower the density of the sealing material produced. The sealing material prepared by the preparation method of the present invention has both excellent tensile properties and peel strength.

[0103] The sealing performance of the expanded polytetrafluoroethylene sealing materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was tested, and the results are shown in Table 2.

[0104] The test method for sealing performance is: test the low-pressure sealing performance according to the method specified in Section 4.5.10 of GJB 8272-2014.

[0105] Table 2

[0106]

[0107] The heat resistance stability of the expanded polytetrafluoroethylene sealing materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was tested, and the results are shown in Table 3.

[0108] Test method for heat stability: Conduct heat stability test according to the provisions of Appendix A of GJB 8272-2014.

[0109] Table 3

[0110]

[0111] It can be seen from Table 2 and Table 3 that, compared with Comparative Examples 1 and 2, the thermal properties of the sealing materials prepared in Examples 1 to 3 are similar, but the sealing effect is better; compared with Comparative Example 3, the thermal properties and sealing effect of the sealing materials prepared in Examples 1 to 3 are improved.

[0112] The reusability of the expanded polytetrafluoroethylene sealing materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was tested, and the results are shown in Table 4.

[0113] Reusability test method: Reusability test shall be carried out in accordance with Section 4.5.11 of GJB 8272-2014.

[0114] Table 4

[0115]

[0116]

[0117] It can be seen from Table 4 that the expanded polytetrafluoroethylene sealing material prepared in the present invention has good reusability and can still maintain its original performance after being reused for many times.

[0118] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an expanded polytetrafluoroethylene sealing material, characterized in that: The steps include: The first expanded polytetrafluoroethylene film, the second expanded polytetrafluoroethylene film and the third expanded polytetrafluoroethylene film are rolled up onto a roller in sequence, and the expanded polytetrafluoroethylene film coated on the roller is laminated while being rolled up onto the roller; after the rolling is completed, the lamination is continued, and after sintering, the expanded polytetrafluoroethylene sealing material is obtained; The thickness of the first expanded polytetrafluoroethylene film is 0.01-0.03 mm, the thickness of the second expanded polytetrafluoroethylene film is 0.06-0.12 mm, the thickness of the third expanded polytetrafluoroethylene film is 0.01-0.03 mm, and the lamination pressure is 0.2-0.3 MPa.

2. The method for preparing expanded polytetrafluoroethylene sealing material according to claim 1, characterized in that: The rolled-up thickness of the first expanded polytetrafluoroethylene film is 0.55-0.65 mm.

3. The method for preparing expanded polytetrafluoroethylene sealing material according to claim 1, characterized in that: The rolled-up thickness of the second expanded polytetrafluoroethylene film is 1.2-1.3 mm.

4. The method for preparing expanded polytetrafluoroethylene sealing material according to claim 1, characterized in that: The rolled-up thickness of the third expanded polytetrafluoroethylene film is 0.55-0.65 mm.

5. The method for preparing expanded polytetrafluoroethylene sealing material according to claim 1, characterized in that: The rotation speed of the roller is 2-6 m / min.

6. The method for preparing expanded polytetrafluoroethylene sealing material according to claim 1, characterized in that: After the rolling is completed, the lamination is continued for 2 to 5 minutes.

7. The method for preparing expanded polytetrafluoroethylene sealing material according to claim 1, characterized in that: The sintering comprises: heat preservation treatment at 360-380° C. for 1-2 hours.

8. The method for preparing an expanded polytetrafluoroethylene sealing material according to any one of claims 1 to 7, characterized in that: The steps include: S1, rolling up the first expanded polytetrafluoroethylene film onto a roller, and performing a first lamination on the expanded polytetrafluoroethylene film coated on the roller to obtain a roller A coated with the film; S2, rolling the second expanded polytetrafluoroethylene film onto the film-coated roller A, and performing a second lamination on the expanded polytetrafluoroethylene film coated on the roller to obtain a film-coated roller B; S3, rolling the third expanded polytetrafluoroethylene film onto the roller B coated with the film, and performing a third lamination on the expanded polytetrafluoroethylene film coated on the roller to obtain a roller C coated with the film; S4, performing a fourth lamination and sintering on the roller C coated with the film to obtain the expanded polytetrafluoroethylene sealing material.

9. An expanded polytetrafluoroethylene sealing material, characterized in that: The expanded polytetrafluoroethylene sealing material is prepared by the preparation method of any one of claims 1 to 8.

10. An aerospace cover structure, characterized in that: It is made from the expanded polytetrafluoroethylene sealing material described in claim 9.

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