Preparation method of fusible polytetrafluoroethylene pipe

Abstract

The invention provides a preparation method of a fusible polytetrafluoroethylene pipe, relates to the technical field of polytetrafluoroethylene, and aims to improve the high temperature resistance of a polytetrafluoroethylene material and enhance the mechanical property of the polytetrafluoroethylene material. The method comprises the following three main steps: S1, mixing tetrafluoroethylene, perfluoroalkyl vinyl ether, octafluorocyclobutane, sodium perfluorooctanoate, ammonium perfluorooctanoate, hydrogen peroxide and a metal oxide, and carrying out electrified modification; s2, adding the carbon fibers and the ceramic fibers into a mixed solution of ethanol, phenol and hydrochloric acid, adding an antioxidant and a nucleating agent, and carrying out heat treatment; and S3, mixing the electrically modified tetrafluoroethylene material, an initiator, a chain transfer agent, the modified carbon fiber and the modified ceramic fiber, reacting under the protection of nitrogen or helium to obtain fusible polytetrafluoroethylene, and performing pushing, extruding, sizing, stretching and cooling to obtain the pipe.

Description

Technical Field

[0001] The invention relates to the technical field of polytetrafluoroethylene, in particular to a method for preparing a fusible polytetrafluoroethylene pipe. Background Art

[0002] As a high-performance material, polytetrafluoroethylene (PTFE) has been widely used in many fields such as chemical industry, electronics, aerospace, etc. due to its excellent chemical stability, high temperature resistance, corrosion resistance and electrical insulation properties. However, traditional PTFE is prone to oxidative degradation in high temperature environments, resulting in a decrease in material performance and shortened service life. In addition, the mechanical properties of traditional PTFE materials are poor and it is difficult to meet the requirements of high strength and high toughness. Summary of the invention

[0003] To achieve the above objectives, the present invention is implemented by the following technical scheme, specifically a method for preparing a fusible polytetrafluoroethylene pipe, comprising the following steps:

[0004] S1. After tetrafluoroethylene, perfluoroalkyl vinyl ether, octafluorocyclobutane, sodium perfluorooctanoate, ammonium perfluorooctanoate, hydrogen peroxide and metal oxide are uniformly mixed, and then subjected to electrical modification. During this process, nitrogen or helium is introduced as a protective gas, the electrode voltage is set to 1000-1200V, the current is controlled at 0.5-0.9A, and the processing time is 2-3min, and finally an electrically modified tetrafluoroethylene material is obtained;

[0005] S2: adding carbon fiber and ceramic fiber to a mixed solution consisting of ethanol, phenol and hydrochloric acid, adding an antioxidant and a nucleating agent thereto, putting the mixture into an autoclave and heating it to 120° C. to 180° C., keeping the temperature for 20 to 30 minutes, cooling and filtering to obtain modified carbon fiber and modified ceramic fiber;

[0006] S3: Add the electrically modified tetrafluoroethylene material, initiator, chain transfer agent, modified carbon fiber and modified ceramic fiber to the reactor in proportion, and react under the protection of nitrogen or helium, control the temperature between 120℃ and 180℃, stir at 100-200rpm, and pressurize to 1.7-2.4MPa at the same time. Release the pressure and cool down after 3-6 hours of reaction to obtain fusible polytetrafluoroethylene, heat the fusible polytetrafluoroethylene to 280℃ to 320℃ to make the fusible polytetrafluoroethylene reach a molten state. Finally, the fusible polytetrafluoroethylene pipe is obtained by pushing, extruding, shaping, stretching and cooling.

[0007] The tetrafluoroethylene, perfluoroalkyl vinyl ether, octafluorocyclobutane, sodium perfluorooctanoate, ammonium perfluorooctanoate, hydrogen peroxide and metal oxide are in parts by weight: 20 to 30 parts of tetrafluoroethylene, 3 to 9 parts of perfluoroalkyl vinyl ether, 15 to 30 parts of octafluorocyclobutane, 1 to 3 parts of sodium perfluorooctanoate, 1 to 2 parts of ammonium perfluorooctanoate, 0.5 to 1 part of hydrogen peroxide and 2 to 4 parts of metal oxide.

[0008] The metal oxide comprises 0.5 to 1 part of zinc oxide (ZnO) and 0.5 to 1 part of iron oxide (Fe 2 O 3 ) 1-2 parts and cobalt tetraoxide (Co 3 O 4 )0.5~1 part; Metal oxides can optimize the thermal conductivity of materials and improve heat dissipation efficiency. The high thermal conductivity of zinc oxide combined with the thermal stability of iron oxide and cobalt tetroxide helps to improve the heat dissipation performance of the material. Zinc oxide can effectively conduct current during the power-on modification process, promote the chemical reaction between polytetrafluoroethylene and other materials, and improve the modification efficiency. Its high electron mobility helps to form a uniform current distribution, thereby improving the modification effect; As a catalyst, iron oxide can accelerate the chemical reaction rate and improve the efficiency of the modification process.

[0009] The carbon fiber, ceramic fiber, mixed solution composed of ethanol, phenol and hydrochloric acid, antioxidant and nucleating agent are composed of 5-15 parts of carbon fiber, 5-10 parts of ceramic fiber, 36-50 parts of mixed solution composed of ethanol, phenol and hydrochloric acid, 0.5-2 parts of antioxidant and 0.5-2 parts of nucleating agent in parts by weight.

[0010] The volume ratio of ethanol, phenol and hydrochloric acid in the mixed solution of ethanol, phenol and hydrochloric acid is 7:1:2; ethanol, as a polar solvent, dissolves impurities and pollutants on the fiber surface and improves the surface activity of the fiber; phenol, as a weakly acidic compound, can undergo esterification reaction with hydroxyl or carboxyl groups on the fiber surface and improve the surface properties of the fiber; the purpose of hydrochloric acid is to dissolve inorganic salts on the fiber surface and further optimize the surface structure of the fiber.

[0011] The antioxidant is tris(nonylphenyl)phosphite, and the nucleating agent is talcum powder or white carbon black.

[0012] The carbon fiber has a length ranging from 5 to 10 millimeters and a diameter ranging from 7 to 8 microns; the ceramic fiber has a length ranging from 3 to 7 millimeters and a diameter ranging from 10 to 15 microns.

[0013] The electrically modified tetrafluoroethylene material, initiator, chain transfer agent, modified carbon fiber and modified ceramic fiber are prepared by weight of 80-90 parts of polytetrafluoroethylene material, 0.1-1 parts of initiator, 0.1-1 parts of chain transfer agent, 5-15 parts of modified carbon fiber and 5-10 parts of modified ceramic fiber.

[0014] The chain transfer agent is methanol or perfluoropolyether carboxylic acid.

[0015] The initiator is di-tert-butyl peroxide or diisopropylbenzene peroxide.

[0016] The present invention provides a method for preparing a fusible polytetrafluoroethylene pipe, which has the following beneficial effects:

[0017] 1. Through electrical modification, zinc oxide (ZnO), iron oxide (Fe 2 O 3 ) and cobalt tetraoxide (Co 3 O 4 ) and other metal oxides, effectively conduct current, promote the chemical reaction of tetrafluoroethylene with other materials, and improve the modification efficiency. The high thermal conductivity of zinc oxide combined with the thermal stability of iron oxide and cobalt tetroxide helps to improve the heat dissipation performance of the material.

[0018] 2. Metal oxides optimize the thermal conductivity of the material and improve the heat dissipation efficiency. These oxides act as catalysts during the electrical modification process, accelerating the chemical reaction rate and significantly improving the mechanical strength and toughness of the material. At the same time, the addition of modified carbon fiber and ceramic fiber further improves the overall performance of the composite material. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Embodiment 1:

[0021] A method for preparing a fusible polytetrafluoroethylene pipe comprises the following steps:

[0022] S1: Take 25 parts of tetrafluoroethylene, 5 parts of perfluoroalkyl vinyl ether, 20 parts of octafluorocyclobutane, 2 parts of sodium perfluorooctanoate, 1.5 parts of ammonium perfluorooctanoate, 0.8 parts of hydrogen peroxide and 2.5 parts of metal oxides (including 0.75 parts of zinc oxide, 1.25 parts of iron oxide and 0.5 parts of cobalt tetroxide), mix them evenly, and then perform electrical modification. During this process, nitrogen was introduced as a protective gas, the electrode voltage was set to 1100V, and the current was controlled at 0.7A. The processing time was 2.5min, and the electrically modified tetrafluoroethylene material was finally obtained;

[0023] S2: 10 parts of carbon fiber and 8 parts of ceramic fiber are added to 40 parts of a mixed solution consisting of ethanol, phenol and hydrochloric acid, and 1 part of an antioxidant and 1 part of a nucleating agent are added thereto, and the mixture is put into an autoclave and heated to 150°C, kept warm for 25 minutes, cooled and filtered to obtain modified carbon fiber and modified ceramic fiber.

[0024] S3: 85 parts of electrically modified tetrafluoroethylene material, 0.5 parts of initiator, 0.5 parts of chain transfer agent, 10 parts of modified carbon fiber and 8 parts of modified ceramic fiber are added to the reactor in proportion, and reacted under the protection of nitrogen, the temperature is controlled between 150°C, the stirring speed is 150rpm, and the pressure is increased to 2MPa. After reacting for 4.5 hours, the pressure is released and the temperature is lowered to obtain fusible polytetrafluoroethylene, and the fusible polytetrafluoroethylene is heated to 300°C to make the soluble polytetrafluoroethylene reach a molten state. Finally, the fusible polytetrafluoroethylene pipe is obtained by pushing, extruding, shaping, stretching and cooling.

[0025] Embodiment 2:

[0026] A method for preparing a fusible polytetrafluoroethylene pipe comprises the following steps:

[0027] S1: Take 28 parts of tetrafluoroethylene, 6 parts of perfluoroalkyl vinyl ether, 25 parts of octafluorocyclobutane, 2.5 parts of sodium perfluorooctanoate, 1.8 parts of ammonium perfluorooctanoate, 0.9 parts of hydrogen peroxide and 3.0 parts of metal oxides (including 0.8 parts of zinc oxide, 1.5 parts of iron oxide and 0.7 parts of cobalt tetroxide), mix them evenly, and then perform electrical modification. In this process, helium is introduced as a protective gas, the electrode voltage is set to 1150V, and the current is controlled at 0.8A. The processing time is 2min, and the electrically modified tetrafluoroethylene material is finally obtained;

[0028] S2: 12 parts of carbon fiber and 9 parts of ceramic fiber are added to 45 parts of a mixed solution consisting of ethanol, phenol and hydrochloric acid, and 1.5 parts of an antioxidant and 1.5 parts of a nucleating agent are added thereto, and the mixture is put into an autoclave and heated to 160°C, kept warm for 28 minutes, cooled and filtered to obtain modified carbon fiber and modified ceramic fiber.

[0029] S3: 88 parts of electrically modified tetrafluoroethylene material, 0.8 parts of initiator, 0.8 parts of chain transfer agent, 12 parts of modified carbon fiber and 9 parts of modified ceramic fiber are added to the reactor in proportion, and reacted under the protection of helium, the temperature is controlled between 160°C, the stirring speed is 180rpm, and the pressure is increased to 2.2MPa. After reacting for 5 hours, the pressure is released and the temperature is lowered to obtain fusible polytetrafluoroethylene, and the fusible polytetrafluoroethylene is heated to 310°C to make the soluble polytetrafluoroethylene reach a molten state. Finally, the fusible polytetrafluoroethylene pipe is obtained by pushing, extruding, shaping, stretching and cooling.

[0030] Embodiment 3:

[0031] A method for preparing a fusible polytetrafluoroethylene pipe comprises the following steps:

[0032] S1: Take 30 parts of tetrafluoroethylene, 7 parts of perfluoroalkyl vinyl ether, 28 parts of octafluorocyclobutane, 3 parts of sodium perfluorooctanoate, 2 parts of ammonium perfluorooctanoate, 1 part of hydrogen peroxide and 4 parts of metal oxides (including 1 part of zinc oxide, 2 parts of iron oxide and 1 part of cobalt tetroxide), mix them evenly, and then perform electrical modification. During this process, nitrogen was introduced as a protective gas, the electrode voltage was set to 1200V, and the current was controlled at 0.9A. The processing time was 3min, and the electrically modified tetrafluoroethylene material was finally obtained;

[0033] S2: 15 parts of carbon fiber and 10 parts of ceramic fiber are added to 50 parts of a mixed solution consisting of ethanol, phenol and hydrochloric acid, and 2 parts of an antioxidant and 2 parts of a nucleating agent are added thereto, and the mixture is put into an autoclave and heated to 170°C, kept warm for 30 minutes, cooled and filtered to obtain modified carbon fiber and modified ceramic fiber.

[0034] S3: 90 parts of electrically modified tetrafluoroethylene material, 1 part of initiator, 1 part of chain transfer agent, 15 parts of modified carbon fiber and 10 parts of modified ceramic fiber are added to the reactor in proportion, and reacted under the protection of nitrogen, the temperature is controlled between 170°C, the stirring speed is 200rpm, and the pressure is increased to 2.4MPa. After reacting for 6 hours, the pressure is released and the temperature is lowered to obtain fusible polytetrafluoroethylene, and the soluble polytetrafluoroethylene is heated to 320°C to make the soluble polytetrafluoroethylene reach a molten state. Finally, the fusible polytetrafluoroethylene pipe is obtained by pushing, extruding, shaping, stretching and cooling.

[0035] Embodiment 4:

[0036] A method for preparing a fusible polytetrafluoroethylene pipe comprises the following steps:

[0037] S1: Take 27 parts of tetrafluoroethylene, 7 parts of perfluoroalkyl vinyl ether, 27 parts of octafluorocyclobutane, 2.7 parts of sodium perfluorooctanoate, 1.7 parts of ammonium perfluorooctanoate, 0.95 parts of hydrogen peroxide and 3.15 parts of metal oxides (including 0.85 parts of zinc oxide, 1.55 parts of iron oxide and 0.75 parts of cobalt tetroxide), mix them evenly, and then perform electrical modification. During this process, nitrogen was introduced as a protective gas, the electrode voltage was set to 1100V, and the current was controlled at 0.75A. The processing time was 2.5min, and the electrically modified tetrafluoroethylene material was finally obtained;

[0038] S2: 11 parts of carbon fiber and 9 parts of ceramic fiber are added to 45 parts of a mixed solution consisting of ethanol, phenol and hydrochloric acid, and 1.5 parts of an antioxidant and 1.5 parts of a nucleating agent are added thereto, and the mixture is put into an autoclave and heated to 155°C, kept warm for 25 minutes, cooled and filtered to obtain modified carbon fiber and modified ceramic fiber.

[0039] S3: 88 parts of electrically modified tetrafluoroethylene material, 0.8 parts of initiator, 0.8 parts of chain transfer agent, 11 parts of modified carbon fiber and 9 parts of modified ceramic fiber are added to the reactor in proportion, and reacted under the protection of nitrogen, the temperature is controlled between 155°C, the stirring speed is 175rpm, and the pressure is increased to 2.1MPa. After reacting for 4.5 hours, the pressure is released and the temperature is lowered to obtain fusible polytetrafluoroethylene, and the soluble polytetrafluoroethylene is heated to 305°C to make the soluble polytetrafluoroethylene reach a molten state. Finally, the fusible polytetrafluoroethylene pipe is obtained by pushing, extruding, shaping, stretching and cooling.

[0040] Embodiment 5:

[0041] A method for preparing a fusible polytetrafluoroethylene pipe comprises the following steps:

[0042] S1: Take 26 parts of tetrafluoroethylene, 8 parts of perfluoroalkyl vinyl ether, 26 parts of octafluorocyclobutane, 2.6 parts of sodium perfluorooctanoate, 1.6 parts of ammonium perfluorooctanoate, 0.92 parts of hydrogen peroxide and 3.0 parts of metal oxides (including 0.8 parts of zinc oxide, 1.5 parts of iron oxide and 0.7 parts of cobalt tetroxide), mix them evenly, and then perform electrical modification. In this process, helium is introduced as a protective gas, the electrode voltage is set to 1120V, and the current is controlled at 0.78A. The processing time is 2min, and the electrically modified tetrafluoroethylene material is finally obtained;

[0043] S2: 13 parts of carbon fiber and 10 parts of ceramic fiber are added to 48 parts of a mixed solution consisting of ethanol, phenol and hydrochloric acid, and 1.8 parts of an antioxidant and 1.8 parts of a nucleating agent are added thereto, and the mixture is put into an autoclave and heated to 165°C, kept warm for 27 minutes, cooled and filtered to obtain modified carbon fiber and modified ceramic fiber.

[0044] S3: 89 parts of electrically modified tetrafluoroethylene material, 0.85 parts of initiator, 0.85 parts of chain transfer agent, 13 parts of modified carbon fiber and 10 parts of modified ceramic fiber are added to the reactor in proportion, and reacted under the protection of helium, the temperature is controlled between 165°C, the stirring speed is 190rpm, and the pressure is increased to 2.3MPa. After reacting for 5.5 hours, the pressure is released and the temperature is lowered to obtain fusible polytetrafluoroethylene, and the fusible polytetrafluoroethylene is heated to 315°C to make the soluble polytetrafluoroethylene reach a molten state. Finally, the fusible polytetrafluoroethylene pipe is obtained by pushing, extruding, shaping, stretching and cooling.

[0045] Embodiment 6:

[0046] A method for preparing a fusible polytetrafluoroethylene pipe comprises the following steps:

[0047] S1: Take 29 parts of tetrafluoroethylene, 9 parts of perfluoroalkyl vinyl ether, 28 parts of octafluorocyclobutane, 2.8 parts of sodium perfluorooctanoate, 1.7 parts of ammonium perfluorooctanoate, 0.98 parts of hydrogen peroxide and 3.3 parts of metal oxides (including 0.9 parts of zinc oxide, 1.6 parts of iron oxide and 0.8 parts of cobalt tetroxide), mix them evenly, and then perform electrical modification. During this process, nitrogen was introduced as a protective gas, the electrode voltage was set to 1150V, and the current was controlled at 0.85A. The processing time was 2.5min, and the electrically modified tetrafluoroethylene material was finally obtained;

[0048] S2: 14 parts of carbon fiber and 9 parts of ceramic fiber are added to 47 parts of a mixed solution consisting of ethanol, phenol and hydrochloric acid, and 1.9 parts of an antioxidant and 1.9 parts of a nucleating agent are added thereto, and the mixture is put into an autoclave and heated to 168°C, kept warm for 28 minutes, cooled and filtered to obtain modified carbon fiber and modified ceramic fiber.

[0049] S3: 90 parts of electrically modified tetrafluoroethylene material, 0.9 parts of initiator, 0.9 parts of chain transfer agent, 14 parts of modified carbon fiber and 9 parts of modified ceramic fiber are added to the reactor in proportion, and reacted under the protection of nitrogen, the temperature is controlled between 168°C, the stirring speed is 195rpm, and the pressure is increased to 2.4MPa. After reacting for 6 hours, the pressure is released and the temperature is lowered to obtain fusible polytetrafluoroethylene, and the fusible polytetrafluoroethylene is heated to 320°C to make the soluble polytetrafluoroethylene reach a molten state. Finally, the fusible polytetrafluoroethylene pipe is obtained by pushing, extruding, shaping, stretching and cooling.

[0050] Embodiment 7:

[0051] A method for preparing a fusible polytetrafluoroethylene pipe comprises the following steps:

[0052] S1: Take 27 parts of tetrafluoroethylene, 5 parts of perfluoroalkyl vinyl ether, 21 parts of octafluorocyclobutane, 2.5 parts of sodium perfluorooctanoate, 1.2 parts of ammonium perfluorooctanoate, 0.90 parts of hydrogen peroxide and 3.1 parts of metal oxides (including 0.8 parts of zinc oxide, 1.6 parts of iron oxide and 0.7 parts of cobalt tetroxide), mix them evenly, and then perform electrical modification. In this process, helium is introduced as a protective gas, the electrode voltage is set to 1120V, and the current is controlled at 0.78A. The processing time is 2min, and the electrically modified tetrafluoroethylene material is finally obtained;

[0053] S2: 12 parts of carbon fiber and 9 parts of ceramic fiber are added to 45 parts of a mixed solution consisting of ethanol, phenol and hydrochloric acid, and 1.5 parts of an antioxidant and 1.5 parts of a nucleating agent are added thereto, and the mixture is put into an autoclave and heated to 152°C, kept warm for 25 minutes, cooled and filtered to obtain modified carbon fiber and modified ceramic fiber.

[0054] S3: 82 parts of electrically modified tetrafluoroethylene material, 0.8 parts of initiator, 0.8 parts of chain transfer agent, 12 parts of modified carbon fiber and 9 parts of modified ceramic fiber are added to the reactor in proportion, and reacted under the protection of helium, the temperature is controlled between 158°C, the stirring speed is 180rpm, and the pressure is increased to 2.2MPa at the same time. The reaction is carried out for 5 hours, the pressure is released and the temperature is lowered to obtain fusible polytetrafluoroethylene, and the soluble polytetrafluoroethylene is heated to 310°C to make the soluble polytetrafluoroethylene reach a molten state. Finally, the fusible polytetrafluoroethylene pipe is obtained by pushing, extruding, shaping, stretching and cooling.

[0055] Embodiment 8:

[0056] A method for preparing a fusible polytetrafluoroethylene pipe comprises the following steps:

[0057] S1: Take 20 parts of tetrafluoroethylene, 4 parts of perfluoroalkyl vinyl ether, 25 parts of octafluorocyclobutane, 2.5 parts of sodium perfluorooctanoate, 1.2 parts of ammonium perfluorooctanoate, 0.5 parts of hydrogen peroxide and 3.0 parts of metal oxides (including 0.8 parts of zinc oxide, 1.5 parts of iron oxide and 0.7 parts of cobalt tetroxide), mix them evenly, and then perform electrical modification. During this process, nitrogen was introduced as a protective gas, the electrode voltage was set to 1150V, and the current was controlled at 0.8A. The processing time was 2 minutes, and the electrically modified tetrafluoroethylene material was finally obtained;

[0058] S2: 13 parts of carbon fiber and 10 parts of ceramic fiber are added to 48 parts of a mixed solution consisting of ethanol, phenol and hydrochloric acid, and 1.6 parts of an antioxidant and 1.8 parts of a nucleating agent are added thereto, and the mixture is put into an autoclave and heated to 165°C, kept warm for 27 minutes, cooled and filtered to obtain modified carbon fiber and modified ceramic fiber.

[0059] S3: 89 parts of electrically modified tetrafluoroethylene material, 0.80 parts of initiator, 0.85 parts of chain transfer agent, 13 parts of modified carbon fiber and 10 parts of modified ceramic fiber are added to the reactor in proportion, and reacted under the protection of nitrogen, the temperature is controlled between 165°C, the stirring speed is 190rpm, and the pressure is increased to 2.3MPa at the same time. The reaction is released after 5.5 hours of pressure and the temperature is lowered to obtain soluble polytetrafluoroethylene. The fusible polytetrafluoroethylene is heated to 315°C to make the soluble polytetrafluoroethylene reach a molten state. Finally, the fusible polytetrafluoroethylene pipe is obtained by pushing, extruding, shaping, stretching and cooling.

[0060] Comparative Example 1:

[0061] In Comparative Example 1, except that zinc oxide was not added, the rest of the raw material ratios, preparation methods, and operating conditions were the same as those of Example 1.

[0062] Comparative Example 2:

[0063] In Comparative Example 2, except that no iron oxide was added, the rest of the raw material ratios, preparation methods, and operating conditions were the same as those in Example 1.

[0064] Comparative Example 3:

[0065] In Comparative Example 3, except that cobalt tetroxide was not added, the rest of the raw material ratios, preparation methods, and operating conditions were the same as those in Example 1.

[0066] Comparative Example 4:

[0067] In Comparative Example 4, except that modified carbon fiber and modified ceramic fiber were not added, the rest of the raw material ratios, preparation methods, and operating conditions were the same as those in Example 1.

[0068] Comparative Example 5:

[0069] In Comparative Example 5, the carbon fiber and ceramic fiber are not modified, and the carbon fiber and ceramic fiber are directly added in step S3. The rest of the raw material ratios, preparation methods, and operating conditions are the same as those in Example 1.

[0070] Performance testing

[0071] The fusible polytetrafluoroethylene pipes prepared in Examples 1 to 3 and Comparative Examples 1 to 5 were respectively taken as test objects, and the tensile strength, compressive strength and shrinkage (%) at 200°C of the fusible polytetrafluoroethylene pipes were tested. The specific test steps and test standards were referred to GB / T1447-2005 "Test Method for Tensile Properties of Fiber Reinforced Plastics", GB / T1039-1992 "General Principles for Test Methods for Mechanical Properties of Plastics" and QB / T4877-2015 "Polytetrafluoroethylene Pipes". The test results are detailed in Table 1:

[0072] Table 1

[0073]

[0074]

[0075] It can be seen from the data of the embodiments and comparative examples in Table 1 that embodiment 5 is the best embodiment, and its compressive strength reaches 35.6 MPa and its tensile strength reaches 50.7 MPa.

[0076] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a fusible polytetrafluoroethylene pipe, characterized in that: The following steps are involved: S1: Tetrafluoroethylene, perfluoroalkyl vinyl ether, octafluorocyclobutane, sodium perfluorooctanoate, ammonium perfluorooctanoate, hydrogen peroxide and metal oxide are uniformly mixed and then electrically modified, nitrogen or helium is introduced as a protective gas, the electrode voltage is 1000-1200V, the current is 0.5-0.9A, and the electrically modified tetrafluoroethylene material is obtained after treating for 2-3 minutes; S2: adding carbon fiber and ceramic fiber to a mixed solution consisting of ethanol, phenol and hydrochloric acid, adding an antioxidant and a nucleating agent thereto, putting the mixture into an autoclave and heating it to 120-180° C., keeping the temperature for 20-30 minutes, cooling and filtering to obtain modified carbon fiber and modified ceramic fiber; S3: Add electrically modified tetrafluoroethylene material, initiator, chain transfer agent, modified carbon fiber and modified ceramic fiber into a reactor in proportion, and react under the protection of nitrogen or helium, control the temperature between 120°C and 180°C, stir at 100-200rpm, and pressurize to 1.7-2.4MPa. Release the pressure and cool after reacting for 3-6 hours to obtain fusible polytetrafluoroethylene. Heat the fusible polytetrafluoroethylene to 280°C-320°C to melt the fusible polytetrafluoroethylene. Finally, obtain a fusible polytetrafluoroethylene pipe by pushing, extruding, shaping, stretching and cooling.

2. A method for preparing a fusible polytetrafluoroethylene pipe according to claim 1, characterized in that: The metal oxide consists of zinc oxide (ZnO), iron oxide (Fe2O3) and cobalt tetraoxide (Co3O4).

3. The method for preparing a fusible polytetrafluoroethylene pipe according to claim 1, characterized in that: The volume ratio of ethanol, phenol and hydrochloric acid in the mixed solution of ethanol, phenol and hydrochloric acid is 7:1:

2.

4. A method for preparing a fusible polytetrafluoroethylene pipe according to claim 1, characterized in that: The antioxidant is tris(nonylphenyl)phosphite, and the nucleating agent is talcum powder or white carbon black.

5. The method for preparing a fusible polytetrafluoroethylene pipe according to claim 1, characterized in that: The chain transfer agent is methanol or perfluoropolyether carboxylic acid.

6. A method for preparing a fusible polytetrafluoroethylene pipe according to claim 1, characterized in that: The initiator is di-tert-butyl peroxide or diisopropylbenzene peroxide.

Images