A preparation method of a soluble polytetrafluoroethylene pipe

Abstract

The present invention provides a method for preparing soluble polytetrafluoroethylene pipes, which relates to the technical field of polytetrafluoroethylene, aiming to improve the high-temperature resistance of polytetrafluoroethylene materials and enhance their mechanical properties at the same time. This method includes three main steps: S1, mixing tetrafluoroethylene, perfluoroalkyl vinyl ether, octafluorocyclobutane, perfluorosodium octanoate, ammonium perfluorooctanoate, hydrogen peroxide and metal oxides, and then carrying out electrification modification; S2, adding carbon fiber and ceramic fiber into a mixed solution of ethanol, phenol and hydrochloric acid, adding antioxidant and nucleating agent, and then carrying out heat treatment; S3, mixing the electrically modified tetrafluoroethylene material, initiator, chain transfer agent, modified carbon fiber and modified ceramic fiber, reacting under the protection of nitrogen or helium to obtain soluble polytetrafluoroethylene, and then making pipes through pushing, extrusion, shaping, stretching and cooling.

Description

Technical Field

[0001] The present invention relates to the technical field of polytetrafluoroethylene, and specifically to a preparation method of soluble polytetrafluoroethylene pipes. Background Art

[0002] Polytetrafluoroethylene (PTFE), as a high-performance material, 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 decline in material properties and a shortened service life. In addition, the mechanical properties of traditional PTFE materials are poor and 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 realized through the following technical solutions. Specifically, it is a preparation method of soluble polytetrafluoroethylene pipes, including the following steps:

[0004] S1. After uniformly mixing tetrafluoroethylene, perfluoroalkyl vinyl ether, octafluorocyclobutane, perfluorosodium octanoate, perfluoroammonium octanoate, hydrogen peroxide and metal oxide, conduct power-on modification. During this process, introduce nitrogen or helium as a protective gas, set the electrode voltage to 1000 - 1200V, control the current at 0.5 - 0.9A, and the treatment time is 2 - 3 minutes to finally obtain an electrically modified tetrafluoroethylene material;

[0005] S2: Add carbon fiber and ceramic fiber to a mixed solution composed of ethanol, phenol and hydrochloric acid, and add an antioxidant and a nucleating agent thereto, then put them into an autoclave and heat to 120°C - 180°C, keep warm for 20 - 30 minutes, and filter after cooling 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 reaction kettle in proportion, and conduct the reaction under the protection of nitrogen or helium. Control the temperature between 120°C and 180°C, the stirring speed is 100 - 200 rpm, and at the same time pressurize to 1.7 - 2.4 MPa. After reacting for 3 - 6 hours, release the pressure and cool down to obtain soluble polytetrafluoroethylene. Heat the soluble polytetrafluoroethylene to 280°C to 320°C to make the soluble polytetrafluoroethylene reach a molten state. Finally, through pushing, extrusion, shaping, stretching and cooling, soluble polytetrafluoroethylene pipes are manufactured.

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

[0008] The metal oxide is composed of 0.5 - 1 part of zinc oxide (ZnO), 1 - 2 parts of iron oxide (Fe2O3) and 0.5 - 1 part of cobalt tetroxide (Co3O4) by weight; the metal oxide can optimize the thermal conductivity of the material and improve the heat dissipation efficiency. The combination of the high thermal conductivity of zinc oxide and 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 electrification modification process, promote the chemical reaction between polytetrafluoroethylene and other materials, and improve the modification efficiency. Its relatively high electron mobility helps to form a uniform current distribution, thus 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 the mixed solution composed of ethanol, phenol and hydrochloric acid, 0.5 - 2 parts of antioxidant and 0.5 - 2 parts of nucleating agent by weight.

[0010] The volume ratio of ethanol, phenol and hydrochloric acid in the mixed solution composed of ethanol, phenol and hydrochloric acid is 7:1:2; ethanol, as a polar solvent, dissolves the impurities and pollutants on the fiber surface and improves the surface activity of the fiber. Phenol, as a weak acidic compound, can undergo an esterification reaction with the hydroxyl or carboxyl groups on the fiber surface to improve the surface properties of the fiber. Hydrochloric acid is used to dissolve the inorganic salts on the fiber surface to 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 length range of the carbon fiber is between 5 - 10 mm, and the diameter is 7 - 8 μm; the length range of the ceramic fiber is between 3 - 7 mm, and the diameter is 10 - 15 μm.

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

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

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

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

[0017] 1. Through electrification modification, using metal oxides such as zinc oxide (ZnO), iron oxide (Fe₂O₃), and cobalt ferrite (Co₃O₄), the current can be effectively conducted, promoting the chemical reaction between tetrafluoroethylene and other materials, and improving the modification efficiency. The high thermal conductivity of zinc oxide combined with the thermal stability of iron oxide and cobalt ferrite helps to improve the heat dissipation performance of the material.

[0018] 2. The metal oxides optimize the thermal conductivity of the material and improve the heat dissipation efficiency. These oxides act as catalysts during the electrification modification process, accelerating the chemical reaction rate, significantly enhancing 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. Specific embodiments

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] Example 1:

[0021] A method for preparing soluble polytetrafluoroethylene pipes includes the following steps:

[0022] S1: Take 25 parts of tetrafluoroethylene, 5 parts of perfluoroalkyl vinyl ether, 20 parts of octafluorocyclobutane, 2 parts of perfluorooctanoic acid sodium, 1.5 parts of perfluorooctanoic acid ammonium, 0.8 part of hydrogen peroxide, and 2.5 parts of metal oxide (including 0.75 part of zinc oxide, 1.25 parts of iron oxide, and 0.5 part of cobalt ferrite). After mixing evenly, carry out electrification modification. During this process, nitrogen is introduced as a protective gas, the electrode voltage is set to 1100V, and the current is controlled at 0.7A. The treatment time is 2.5 min, and finally, an electrically modified tetrafluoroethylene material is obtained;

[0023] S2: Add 10 parts of carbon fiber and 8 parts of ceramic fiber into 40 parts of a mixed solution composed of ethanol, phenol, and hydrochloric acid, and add 1 part of antioxidant and 1 part of nucleating agent thereto. Then put them into an autoclave and heat to 150 °C, keep warm for 25 min, and filter after cooling to obtain modified carbon fiber and modified ceramic fiber.

[0024] S3: Add 85 parts of electro-modified tetrafluoroethylene material, 0.5 part of initiator, 0.5 part of chain transfer agent, 10 parts of modified carbon fiber and 8 parts of modified ceramic fiber into the reaction kettle in proportion, and carry out the reaction under the protection of nitrogen. Control the temperature between 150°C, the stirring speed is 150 rpm, and at the same time pressurize to 2 MPa. After reacting for 4.5 hours, release the pressure and cool down to obtain soluble polytetrafluoroethylene. Heat the soluble polytetrafluoroethylene to 300°C to make the soluble polytetrafluoroethylene reach the molten state. Finally, through pushing, extrusion, shaping, stretching and cooling, the soluble polytetrafluoroethylene pipe is prepared.

[0025] Example 2:

[0026] A method for preparing a soluble polytetrafluoroethylene pipe, comprising the following steps:

[0027] S1: Take 28 parts of tetrafluoroethylene, 6 parts of perfluoroalkyl vinyl ether, 25 parts of octafluorocyclobutane, 2.5 parts of perfluorosodium octanoate, 1.8 parts of perfluorooctanoic acid ammonium, 0.9 part of hydrogen peroxide and 3.0 parts of metal oxide (where 0.8 part of zinc oxide, 1.5 parts of iron oxide and 0.7 part of cobalt tetroxide), mix them evenly, and then carry out electro-modification. During this process, helium is introduced as the protective gas, the electrode voltage is set at 1150 V, and the current is controlled at 0.8 A. The treatment time is 2 min, and finally the electro-modified tetrafluoroethylene material is obtained;

[0028] S2: Add 12 parts of carbon fiber and 9 parts of ceramic fiber into 45 parts of the mixed solution composed of ethanol, phenol and hydrochloric acid, and add 1.5 parts of antioxidant and 1.5 parts of nucleating agent to it, then put them into the autoclave and heat to 160°C, keep warm for 28 min, and filter after cooling to obtain modified carbon fiber and modified ceramic fiber.

[0029] S3: Add 88 parts of electro-modified tetrafluoroethylene material, 0.8 part of initiator, 0.8 part of chain transfer agent, 12 parts of modified carbon fiber and 9 parts of modified ceramic fiber into the reaction kettle in proportion, and carry out the reaction under the protection of helium. Control the temperature between 160°C, the stirring speed is 180 rpm, and at the same time pressurize to 2.2 MPa. After reacting for 5 hours, release the pressure and cool down to obtain soluble polytetrafluoroethylene. Heat the soluble polytetrafluoroethylene to 310°C to make the soluble polytetrafluoroethylene reach the molten state. Finally, through pushing, extrusion, shaping, stretching and cooling, the soluble polytetrafluoroethylene pipe is prepared.

[0030] Example 3:

[0031] A method for preparing a soluble polytetrafluoroethylene pipe, comprising the following steps:

[0032] S1: Take 30 parts of tetrafluoroethylene, 7 parts of perfluoroalkyl vinyl ether, 28 parts of octafluorocyclobutane, 3 parts of perfluorosodium octanoate, 2 parts of perfluoroammonium octanoate, 1 part of hydrogen peroxide, and 4 parts of metal oxide (including 1 part of zinc oxide, 2 parts of iron oxide, and 1 part of cobalt tetroxide). After mixing evenly, conduct electrification modification. During this process, introduce nitrogen as the protective gas, set the electrode voltage to 1200V, and control the current at 0.9A. The treatment time is 3 minutes, and finally obtain the electrically modified tetrafluoroethylene material;

[0033] S2: Add 15 parts of carbon fiber and 10 parts of ceramic fiber to 50 parts of a mixed solution composed of ethanol, phenol, and hydrochloric acid, and add 2 parts of antioxidant and 2 parts of nucleating agent thereto. Then put them into an autoclave and heat to 170°C, keep warm for 30 minutes, and filter after cooling to obtain modified carbon fiber and modified ceramic fiber.

[0034] S3: Add 90 parts of the 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 to the reaction kettle in proportion, and carry out the reaction under the protection of nitrogen. Control the temperature between 170°C, the stirring speed is 200rpm, and at the same time pressurize to 2.4MPa. After reacting for 6 hours, release the pressure and cool down to obtain soluble polytetrafluoroethylene. Heat the soluble polytetrafluoroethylene to 320°C to make the soluble polytetrafluoroethylene reach the molten state. Finally, through pushing, extrusion, shaping, stretching, and cooling, produce soluble polytetrafluoroethylene pipes.

[0035] Example 4:

[0036] A preparation method of soluble polytetrafluoroethylene pipes, comprising the following steps:

[0037] S1: Take 27 parts of tetrafluoroethylene, 7 parts of perfluoroalkyl vinyl ether, 27 parts of octafluorocyclobutane, 2.7 parts of perfluorosodium octanoate, 1.7 parts of perfluoroammonium octanoate, 0.95 part of hydrogen peroxide, and 3.15 parts of metal oxide (including 0.85 part of zinc oxide, 1.55 parts of iron oxide, and 0.75 part of cobalt tetroxide). After mixing evenly, conduct electrification modification. During this process, introduce nitrogen as the protective gas, set the electrode voltage to 1100V, and control the current at 0.75A. The treatment time is 2.5 minutes, and finally obtain the electrically modified tetrafluoroethylene material;

[0038] S2: Add 11 parts of carbon fiber and 9 parts of ceramic fiber to 45 parts of a mixed solution composed of ethanol, phenol, and hydrochloric acid, and add 1.5 parts of antioxidant and 1.5 parts of nucleating agent thereto. Then put them into an autoclave and heat to 155°C, keep warm for 25 minutes, and filter after cooling to obtain modified carbon fiber and modified ceramic fiber.

[0039] S3: Add 88 parts of electro-modified tetrafluoroethylene material, 0.8 part of initiator, 0.8 part of chain transfer agent, 11 parts of modified carbon fiber and 9 parts of modified ceramic fiber into the reaction kettle in proportion, and carry out the reaction under the protection of nitrogen. Control the temperature between 155 °C, the stirring speed is 175 rpm, and at the same time pressurize to 2.1 MPa. After reacting for 4.5 hours, release the pressure and cool down to obtain soluble polytetrafluoroethylene. Heat the soluble polytetrafluoroethylene to 305 °C to make the soluble polytetrafluoroethylene reach the molten state. Finally, through pushing, extrusion, shaping, stretching and cooling, the soluble polytetrafluoroethylene pipe is prepared.

[0040] Example 5:

[0041] A method for preparing a soluble polytetrafluoroethylene pipe, comprising the following steps:

[0042] S1: Take 26 parts of tetrafluoroethylene, 8 parts of perfluoroalkyl vinyl ether, 26 parts of octafluorocyclobutane, 2.6 parts of perfluorosodium octanoate, 1.6 parts of perfluoroammonium octanoate, 0.92 part of hydrogen peroxide and 3.0 parts of metal oxide (where 0.8 part of zinc oxide, 1.5 parts of iron oxide and 0.7 part of cobalt tetroxide), mix evenly and then carry out electro-modification. During this process, helium is introduced as the protective gas, the electrode voltage is set at 1120 V, and the current is controlled at 0.78 A. The treatment time is 2 min, and finally the electro-modified tetrafluoroethylene material is obtained;

[0043] S2: Add 13 parts of carbon fiber and 10 parts of ceramic fiber into 48 parts of the mixed solution composed of ethanol, phenol and hydrochloric acid, and add 1.8 parts of antioxidant and 1.8 parts of nucleating agent thereto, and put them into the autoclave and heat to 165 °C, keep warm for 27 min, and filter after cooling to obtain modified carbon fiber and modified ceramic fiber.

[0044] S3: Add 89 parts of electro-modified tetrafluoroethylene material, 0.85 part of initiator, 0.85 part of chain transfer agent, 13 parts of modified carbon fiber and 10 parts of modified ceramic fiber into the reaction kettle in proportion, and carry out the reaction under the protection of helium. Control the temperature between 165 °C, the stirring speed is 190 rpm, and at the same time pressurize to 2.3 MPa. After reacting for 5.5 hours, release the pressure and cool down to obtain soluble polytetrafluoroethylene. Heat the soluble polytetrafluoroethylene to 315 °C to make the soluble polytetrafluoroethylene reach the molten state. Finally, through pushing, extrusion, shaping, stretching and cooling, the soluble polytetrafluoroethylene pipe is prepared.

[0045] Example 6:

[0046] A method for preparing a soluble polytetrafluoroethylene pipe, comprising the following steps:

[0047] S1: Take 29 parts of tetrafluoroethylene, 9 parts of perfluoroalkyl vinyl ether, 28 parts of octafluorocyclobutane, 2.8 parts of perfluorosodium octanoate, 1.7 parts of perfluoroammonium octanoate, 0.98 parts of hydrogen peroxide, and 3.3 parts of metal oxide (including 0.9 part of zinc oxide, 1.6 parts of iron oxide, and 0.8 part of cobalt tetroxide). After mixing evenly, carry out electro-modification. During this process, introduce nitrogen as the protective gas, set the electrode voltage to 1150V, and control the current at 0.85A. The treatment time is 2.5 min, and finally obtain electro-modified tetrafluoroethylene material;

[0048] S2: Add 14 parts of carbon fiber and 9 parts of ceramic fiber into 47 parts of the mixed solution composed of ethanol, phenol, and hydrochloric acid, and add 1.9 parts of antioxidant and 1.9 parts of nucleating agent thereto. Then put them into an autoclave and heat to 168°C, keep warm for 28 min, and filter after cooling to obtain modified carbon fiber and modified ceramic fiber.

[0049] S3: Add 90 parts of electro-modified tetrafluoroethylene material, 0.9 part of initiator, 0.9 part of chain transfer agent, 14 parts of modified carbon fiber, and 9 parts of modified ceramic fiber into the reaction kettle according to the proportion, and carry out the reaction under the protection of nitrogen. Control the temperature between 168°C, the stirring speed is 195 rpm, and at the same time pressurize to 2.4 MPa. After reacting for 6 hours, release the pressure and cool down to obtain soluble polytetrafluoroethylene. Heat the soluble polytetrafluoroethylene to 320°C to make the soluble polytetrafluoroethylene reach the molten state. Finally, through pushing, extrusion, shaping, stretching, and cooling, produce soluble polytetrafluoroethylene pipes.

[0050] Example 7:

[0051] A preparation method of soluble polytetrafluoroethylene pipes, comprising the following steps:

[0052] S1: Take 27 parts of tetrafluoroethylene, 5 parts of perfluoroalkyl vinyl ether, 21 parts of octafluorocyclobutane, 2.5 parts of perfluorosodium octanoate, 1.2 parts of perfluoroammonium octanoate, 0.90 parts of hydrogen peroxide, and 3.1 parts of metal oxide (including 0.8 part of zinc oxide, 1.6 parts of iron oxide, and 0.7 part of cobalt tetroxide). After mixing evenly, carry out electro-modification. During this process, introduce helium as the protective gas, set the electrode voltage to 1120V, and control the current at 0.78A. The treatment time is 2 min, and finally obtain electro-modified tetrafluoroethylene material;

[0053] S2: Add 12 parts of carbon fiber and 9 parts of ceramic fiber into 45 parts of the mixed solution composed of ethanol, phenol, and hydrochloric acid, and add 1.5 parts of antioxidant and 1.5 parts of nucleating agent thereto. Then put them into an autoclave and heat to 152°C, keep warm for 25 min, and filter after cooling to obtain modified carbon fiber and modified ceramic fiber.

[0054] S3: Add 82 parts of electro-modified tetrafluoroethylene material, 0.8 part of initiator, 0.8 part of chain transfer agent, 12 parts of modified carbon fiber and 9 parts of modified ceramic fiber into the reaction kettle in proportion, and carry out the reaction under the protection of helium. Control the temperature between 158 °C, the stirring speed is 180 rpm, and at the same time pressurize to 2.2 MPa. After reacting for 5 hours, release the pressure and cool down to obtain soluble polytetrafluoroethylene. Heat the soluble polytetrafluoroethylene to 310 °C to make the soluble polytetrafluoroethylene reach the molten state. Finally, through pushing, extrusion, shaping, stretching and cooling, the soluble polytetrafluoroethylene pipe is prepared.

[0055] Example 8:

[0056] A preparation method of soluble polytetrafluoroethylene pipe, comprising the following steps:

[0057] S1: Take 20 parts of tetrafluoroethylene, 4 parts of perfluoroalkyl vinyl ether, 25 parts of octafluorocyclobutane, 2.5 parts of perfluorosodium octanoate, 1.2 parts of ammonium perfluorooctanoate, 0.5 part of hydrogen peroxide and 3.0 parts of metal oxide (where 0.8 part of zinc oxide, 1.5 parts of iron oxide and 0.7 part of cobalt tetroxide), mix evenly, and then carry out electro-modification. During this process, introduce nitrogen as the protective gas, set the electrode voltage to 1150 V, and control the current at 0.8 A. The treatment time is 2 min, and finally the electro-modified tetrafluoroethylene material is obtained;

[0058] S2: Add 13 parts of carbon fiber and 10 parts of ceramic fiber into 48 parts of the mixed solution composed of ethanol, phenol and hydrochloric acid, and add 1.6 parts of antioxidant and 1.8 parts of nucleating agent thereto, and put them into the autoclave and heat to 165 °C, keep warm for 27 min, and filter after cooling to obtain modified carbon fiber and modified ceramic fiber.

[0059] S3: Add 89 parts of electro-modified tetrafluoroethylene material, 0.80 part of initiator, 0.85 part of chain transfer agent, 13 parts of modified carbon fiber and 10 parts of modified ceramic fiber into the reaction kettle in proportion, and carry out the reaction under the protection of nitrogen. Control the temperature between 165 °C, the stirring speed is 190 rpm, and at the same time pressurize to 2.3 MPa. After reacting for 5.5 hours, release the pressure and cool down to obtain soluble polytetrafluoroethylene. Heat the soluble polytetrafluoroethylene to 315 °C to make the soluble polytetrafluoroethylene reach the molten state. Finally, through pushing, extrusion, shaping, stretching and cooling, the soluble polytetrafluoroethylene pipe is prepared.

[0060] Comparative Example 1:

[0061] In Comparative Example 1, except that zinc oxide is not added, the raw material ratio, preparation method, operating conditions are the same as those in Example 1.

[0062] Comparative Example 2:

[0063] Comparative Example 2 was the same as Example 1 in terms of the raw material ratio, preparation method, operating conditions, except that iron oxide was not added.

[0064] Comparative Example 3:

[0065] Comparative Example 3 was the same as Example 1 in terms of the raw material ratio, preparation method, operating conditions, except that cobalt tetroxide was not added.

[0066] Comparative Example 4:

[0067] Comparative Example 4 was the same as Example 1 in terms of the raw material ratio, preparation method, operating conditions, except that modified carbon fiber and modified ceramic fiber were not added.

[0068] Comparative Example 5:

[0069] Comparative Example 5 was the same as Example 1 in terms of the raw material ratio, preparation method, operating conditions, except that the carbon fiber and ceramic fiber were not modified, and the carbon fiber and ceramic fiber were directly added in Step S3.

[0070] Performance detection test

[0071] The soluble polytetrafluoroethylene pipes prepared in Examples 1 to 3 and Comparative Examples 1 to 5 were respectively taken as the test objects, and the tensile strength, compressive strength and shrinkage rate (%) at 200 °C of the soluble polytetrafluoroethylene pipes were tested. The specific detection steps and detection standards refer to GB / T 1447-2005 "Test Methods for Tensile Properties of Fiber Reinforced Plastics", GB / T 1039-1992 "General Rules for Test Methods of Mechanical Properties of Plastics" and QB / T 4877-2015 "Polytetrafluoroethylene Pipes". The test results are shown in Table 1:

[0072] Table 1

[0073]

[0074]

[0075] It can be seen from the data of the examples and comparative examples in Table 1 that Example 5 is the optimal example, with a compressive strength of 35.6 Mpa and a tensile strength of 50.7 Mpa.

[0076] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a soluble polytetrafluoroethylene pipe, characterized in that, It includes the following steps: S1: Tetrafluoroethylene, perfluoroalkyl vinyl ether, octafluorocyclobutane, sodium perfluorooctanoate, ammonium perfluorooctanoate, hydrogen peroxide, and metal oxide are mixed evenly and then subjected to electrification modification. Nitrogen or helium is introduced as a protective gas. The electrode voltage is 1000 - 1200V, the input current is 0.5 - 0.9A, and after treatment for 2 - 3 minutes, an electro-modified tetrafluoroethylene material is obtained; S2: Carbon fiber and ceramic fiber are added to a mixed solution composed of ethanol, phenol, and hydrochloric acid, and an antioxidant and a nucleating agent are added thereto. The mixture is put into an autoclave and heated to 120 - 180°C, kept warm for 20 - 30 minutes, and after cooling, it is filtered to obtain modified carbon fiber and modified ceramic fiber; S3: The electro-modified tetrafluoroethylene material, initiator, chain transfer agent, modified carbon fiber, and modified ceramic fiber are added to a reaction kettle in proportion and reacted under the protection of nitrogen or helium. The temperature is controlled between 120°C and 180°C, the stirring speed is 100 - 200 rpm, and at the same time, the pressure is increased to 1.7 - 2.4 MPa. After reacting for 3 - 6 hours, the pressure is released and the temperature is decreased to obtain soluble polytetrafluoroethylene. The soluble polytetrafluoroethylene is heated to 280°C - 320°C to make the soluble polytetrafluoroethylene reach a molten state. Finally, through pushing, extrusion, shaping, stretching, and cooling, soluble polytetrafluoroethylene pipes are manufactured; The metal oxide is composed of zinc oxide (ZnO), iron oxide (Fe2O3), and cobalt tetroxide (Co3O4).

2. The preparation method of a soluble polytetrafluoroethylene pipe according to claim 1, characterized in that: The volume ratio of ethanol, phenol, and hydrochloric acid in the mixed solution composed of ethanol, phenol, and hydrochloric acid is 7:1:

2.

3. A method for preparing a soluble 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.

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

5. 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.

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