Polytetrafluoroethylene sealing element material and manufacturing method thereof

Abstract

The invention particularly relates to a polytetrafluoroethylene sealing element material and a manufacturing method thereof. The polytetrafluoroethylene sealing element material comprises the following raw materials in parts by weight: 70-99 parts of modified polytetrafluoroethylene resin, 5-15 parts of glass fibers, 3-10 parts of carbon fibers, 2-10 parts of bronze powder, 0.5-1 part of furan ring-containing thermosetting resin microcapsules, 0.5-2 parts of multiwalled carbon nanotubes, 0-5 parts of a lubricant and 0-3 parts of a functional aid. According to the polytetrafluoroethylene sealing element material disclosed by the invention, the mechanical property, wear resistance and sealing property of a sealing element are remarkably improved by optimizing the types and contents of the filling agent, the lubricating agent and the functional additive, and the sealing element disclosed by the invention is suitable for sealing application in high-temperature, high-pressure and strong-corrosion environments and has a wide market prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of seal manufacturing, and particularly relates to a polytetrafluoroethylene seal material and a manufacturing method thereof. Background Art

[0002] Seals play a crucial role in many industrial fields, and their performance directly affects the normal operation and safety of equipment. Due to its excellent chemical stability, low friction coefficient and other characteristics, polytetrafluoroethylene is widely used in seal manufacturing. However, the mechanical properties of pure polytetrafluoroethylene such as wear resistance and creep resistance need to be improved, and it is difficult to meet the requirements of some special working conditions. In the prior art, the performance of polytetrafluoroethylene is usually improved by adding fillers (such as glass fiber, carbon fiber, etc.), but the existing formulations and processes still have the following problems:

[0003] (1) The dispersion of the filler is poor, resulting in uneven performance of the seal;

[0004] (2) The manufacturing process is complex and the cost is high;

[0005] (3) The service life of the seal is short under high temperature and high pressure environments.

[0006] Therefore, it is of great significance to develop a polytetrafluoroethylene seal material with better performance and a manufacturing method thereof. Summary of the Invention

[0007] In order to overcome the disadvantages and deficiencies existing in the prior art, the purpose of the present invention is to provide a polytetrafluoroethylene seal material and a manufacturing method thereof.

[0008] The purpose of the present invention is achieved by the following technical solutions: a polytetrafluoroethylene seal material and a manufacturing method thereof, including the following raw materials in parts by weight: 70-99 parts of modified polytetrafluoroethylene resin, 5-15 parts of glass fiber, 3-10 parts of carbon fiber, 2-10 parts of bronze powder, 0.5-1 part of thermosetting resin microcapsule containing furan ring, 0.5-2 parts of multi-walled carbon nanotube, 0-5 parts of lubricant, and 0-3 parts of functional additive.

[0009] Further, the modification method of the polytetrafluoroethylene resin includes the following steps: putting the dried polytetrafluoroethylene resin into a sodium naphthalene solution and soaking for 5-30 minutes, immediately taking it out after soaking and washing the residual sodium naphthalene solution on the surface of the polytetrafluoroethylene resin with an organic solvent and deionized water in sequence, and drying after washing; the drying temperature is 100-120 °C, the drying time is 2-4 hours; the water content of the modified polytetrafluoroethylene resin is less than 0.02%.

[0010] Further, the volume ratio of the polytetrafluoroethylene resin to the sodium naphthalene solution is 1:1.2-2.

[0011] Furthermore, the preparation method of the sodium naphthalene solution comprises the following steps: add 450 - 550 g of naphthalene into 900 - 1000 mL of tetrahydrofuran, and after complete dissolution, slowly add 90 g of sodium in several portions, and stir at room temperature until the sodium is completely dissolved.

[0012] Furthermore, the lubricant is at least one of molybdenum disulfide, graphite, and nano boron nitride.

[0013] Furthermore, each portion of the lubricant comprises the following raw materials in parts by weight: 1 - 3 parts of molybdenum disulfide, 1 - 2 parts of graphite, and 1 - 3 parts of nano boron nitride.

[0014] Furthermore, each portion of the functional auxiliary agent comprises the following raw materials in parts by weight: 0.5 - 1.5 parts of antioxidant, 0.3 - 1 part of light stabilizer, and 0.5 - 1.5 parts of coupling agent.

[0015] Furthermore, the antioxidant is a phenolic antioxidant and a thioester antioxidant; the phenolic antioxidant is selected from at least one of BHT and antioxidant 1010, and the thioester antioxidant is DLTP.

[0016] Furthermore, the light stabilizer is a hindered amine light stabilizer, and the hindered amine light stabilizer is selected from at least one of light stabilizer 944 and light stabilizer LQ - 622.

[0017] Furthermore, the coupling agent is a silane coupling agent and a titanate coupling agent; the silane coupling agent is selected from at least one of KH550 and A - 151, and the titanate coupling agent is KR - 12.

[0018] Furthermore, the length of the glass fiber is 3 - 5 mm, and the diameter is 10 - 15 μm; the length of the carbon fiber is 1 - 3 mm, and the diameter is 7 - 10 μm; the particle size of the bronze powder is less than 300 mesh; the particle size of the molybdenum disulfide is less than 400 mesh; the particle size of the graphite is less than 200 mesh; the particle size of the nano boron nitride is 50 - 100 nm; the particle size of the thermosetting resin microcapsule containing a furan ring is 1 - 100 μm; the inner diameter of the multi - walled carbon nanotube is 5 - 10 nm, the outer diameter is 10 - 20 nm, and the length is 10 - 30 μm.

[0019] Furthermore, the weight ratio of the core material to the wall material of the thermosetting resin microcapsule containing a furan ring is 3:7. The core material is furfuryl alcohol resin, and the wall material is silica and calcium carbonate; the model of the furfuryl alcohol resin is Huilong Chemical Industry FN - 4; the weight ratio of silica to calcium carbonate is 3:1.

[0020] In the present invention, glass fibers are added to polytetrafluoroethylene resin, increasing the hardness of the material and improving its wear resistance to a certain extent; carbon fibers in the present invention form a good interfacial bond with the resin matrix, significantly enhancing the mechanical properties of the material; bronze powder in the present invention can improve the thermal conductivity of the material, reduce the influence of heat generated by friction on the performance of the seal, and the hardness of the bronze powder also helps to improve the wear resistance of the seal and can play a certain supporting role in terms of compression resistance; the layered structures of molybdenum disulfide and graphite can slide at the friction interface, playing a lubricating role; the nano-scale size of nano boron nitride enables it to be evenly dispersed in the polytetrafluoroethylene matrix, effectively filling the microscopic defects in the matrix and enhancing the compression resistance and wear resistance of the seal; when the thermosetting resin microcapsule containing furan rings is slightly damaged, it ruptures due to stress concentration and releases furan rings, and the furan rings react with the active groups on the surface of multi-walled carbon nanotubes pre-dispersed in the matrix to achieve self-repair of the seal. After being modified with sodium naphthalene solution, the surface polarity and adhesion performance of polytetrafluoroethylene are significantly enhanced, significantly improving the surface polarity and surface energy of polytetrafluoroethylene.

[0021] Another object of the present invention is to provide a method for manufacturing a polytetrafluoroethylene seal, comprising the following steps:

[0022] (1) Mixing: Input each raw material according to parts by weight into a high-speed mixer and mix evenly to obtain mixture A, and the rotation speed of the mixer is 1500 r / min;

[0023] (2) Forming: Mixture A is formed into blank B by compression molding or extrusion molding;

[0024] (3) Sintering: Blank B is sintered at a temperature of 370 - 390 °C for 1 - 4 hours;

[0025] (4) Cooling: The sintered blank B is cooled by natural cooling or by controlling the cooling rate;

[0026] (5) Turning: The cooled blank B is turned to obtain product C; the turning speed is 100 - 500 m / min, the feed rate is 0.05 - 0.2 mm / r, and the cutting depth is 0.5 - 2 mm;

[0027] (6) Post-treatment: Product C is cleaned and inspected.

[0028] In the present invention, different forming methods are used for seals with different shapes. For some seals with regular shapes and large batches, compression molding is used, and for tubular or seals with continuous shapes, extrusion molding is used. Sintering enables the raw material particles to fuse with each other, improving the density and strength of the material. The use of coolant during turning can effectively reduce the cutting temperature, prevent material softening and tool wear.

[0029] Further, in step (2), the compression molding is to hold the mixture A under a pressure of 10 - 30 MPa and a temperature of 360 - 380 °C for 10 - 30 minutes.

[0030] Further, in step (2), the extrusion molding is to extrude the mixture A at a temperature of 320 - 360 °C through a screw extruder and a specific die orifice, and then cool and size it by air cooling or water cooling after extrusion.

[0031] Further, in step (5), a water-soluble cutting fluid is used as the coolant during the turning process, and the coolant flow rate is 5 - 10 L / min.

[0032] Further, in step (5), the surface roughness of the product C is Ra0.8 - Ra3.2 μm.

[0033] Further, in step (6), the cleaning process is to soak the product C in an organic solvent or a special plastic cleaning agent for 10 - 30 minutes, and then rinse it thoroughly with clean water.

[0034] By reasonably matching the raw material ratio of the polytetrafluoroethylene resin seal and controlling the process parameters of each step in the preparation method of the polytetrafluoroethylene resin seal, in this invention, mixing each raw material evenly by a high-speed mixer can ensure the uniformity of components, make the polytetrafluoroethylene resin, filler, functional additives, and lubricant disperse evenly in the resin matrix, improve the processing performance, and ensure the consistency of the fluidity of the material during processing.

[0035] The beneficial effects of this invention are as follows: In the polytetrafluoroethylene resin seal of this invention, raw materials such as glass fiber, carbon fiber, bronze powder, thermosetting resin microcapsules containing furan rings, and multi-walled carbon nanotubes are added to the modified polytetrafluoroethylene resin, and functional additives and lubricants are added. Each raw material cooperates with each other, not only fully exerting the advantages of the chemical stability and low friction coefficient of polytetrafluoroethylene, but also improving the mechanical strength, creep resistance, electrical conductivity, thermal conductivity, and load-bearing capacity of the seal through fillers and functional additives. Further reducing the friction coefficient through lubricants and functional additives, improving the self-lubricating performance and heat resistance, it can meet the performance requirements of seals in different industrial fields and has broad application prospects. Specific Embodiments

[0036] For the convenience of understanding by those skilled in the art, the present invention will be further described below in conjunction with embodiments. The content mentioned in the embodiments does not limit the present invention.

[0037] In some embodiments of the present invention, a polytetrafluoroethylene sealing material and its manufacturing method include the following raw materials in parts by weight: 70-99 parts of modified polytetrafluoroethylene resin, 5-15 parts of glass fiber, 3-10 parts of carbon fiber, 2-10 parts of bronze powder, 0.5-1 part of thermosetting resin microcapsule containing furan ring, 0.5-2 parts of multi-walled carbon nanotubes, 0-5 parts of lubricant, and 0-3 parts of functional additive.

[0038] In some embodiments of the present invention, the modification method of the polytetrafluoroethylene resin includes the following steps: putting the dried polytetrafluoroethylene resin into a sodium naphthalene solution and soaking it for 5-30 minutes, immediately taking it out after soaking and washing the residual sodium naphthalene solution on the surface of the polytetrafluoroethylene resin with an organic solvent or deionized water, and drying it after washing; the drying temperature is 100-120°C, and the drying time is 2-4 hours; the water content of the modified polytetrafluoroethylene resin is less than 0.02%.

[0039] In some embodiments of the present invention, the volume ratio of the polytetrafluoroethylene resin to the sodium naphthalene solution is 1:1.2-2.

[0040] In some embodiments of the present invention, the preparation method of the sodium naphthalene solution includes the following steps: adding 450-550 grams of naphthalene to 900-1000 milliliters of tetrahydrofuran, completely dissolving it and then slowly adding 90 grams of sodium in several portions, and stirring at room temperature until the sodium is completely dissolved.

[0041] In some embodiments of the present invention, the lubricant is at least one of molybdenum disulfide, graphite, and nano boron nitride.

[0042] In some embodiments of the present invention, each part of the lubricant includes the following raw materials in parts by weight: 1-3 parts of molybdenum disulfide, 1-2 parts of graphite, and 1-3 parts of nano boron nitride.

[0043] In some embodiments of the present invention, each part of the functional additive includes the following raw materials in parts by weight: 0.5-1.5 parts of antioxidant, 0.3-1 part of light stabilizer, and 0.5-1.5 parts of coupling agent.

[0044] In some embodiments of the present invention, the antioxidant is a phenolic antioxidant and a thioester antioxidant; the phenolic antioxidant is selected from at least one of BHT and antioxidant 1010, and the thioester antioxidant is selected from DLTP.

[0045] In some embodiments of the present invention, the light stabilizer is a hindered amine light stabilizer, and the hindered amine light stabilizer is selected from at least one of light stabilizer 944 and light stabilizer LQ-622.

[0046] In some embodiments of the present invention, the coupling agent is a silane coupling agent or a titanate coupling agent, the silane coupling agent is at least one of KH550 and A-151, and the titanate coupling agent is KR-12.

[0047] In some embodiments of the present invention, the length of the glass fiber is 3-5 mm and the diameter is 10-15 μm; the length of the carbon fiber is 1-3 mm and the diameter is 7-10 μm; the particle size of the bronze powder is less than 300 mesh; the particle size of the molybdenum disulfide is less than 400 mesh; the particle size of the graphite is less than 200 mesh; the particle size of the nano-boron nitride is 50-100 nm; the particle size of the thermosetting resin microcapsules containing furan rings is 1-100 μm; the inner diameter of the multi-walled carbon nanotubes is 5-10 nm, the outer diameter is 10-20 nm, and the length is 10-30 μm.

[0048] In some embodiments of the present invention, the weight ratio of the core material to the wall material of the furan ring-containing thermosetting resin microcapsules is 3:7, the core material is furfuryl alcohol resin, and the wall material is silica and calcium carbonate; the model of the furfuryl alcohol resin is Huilong Chemical FN-4; the weight ratio of silica to calcium carbonate is 3:1.

[0049] Another object of the present invention is to provide a method for manufacturing a polytetrafluoroethylene seal, comprising the following steps:

[0050] (1) Mixing: Each raw material was put into a high-speed mixer according to weight and mixed uniformly to obtain a mixture A. The speed of the mixer was 1500 r / min;

[0051] (2) Molding: Mixed material A is molded or extruded to obtain blank B;

[0052] (3) Sintering: Blank B is sintered at a temperature of 370-390°C for 1-4 hours;

[0053] (4) Cooling: Cooling the sintered blank B by natural cooling or controlling the cooling rate;

[0054] (5) Turning: The cooled blank B is turned to obtain product C; the turning speed is 100-500 m / min, the feed rate is 0.05-0.2 mm / r, and the cutting depth is 0.5-2 mm;

[0055] (6) Post-processing: Clean and inspect product C.

[0056] In some embodiments of the present invention, in step (2), the compression molding is to maintain the mixture A at a pressure of 10-30 MPa and a temperature of 360-380° C. for 10-30 minutes.

[0057] In some embodiments of the present invention, in step (2), the extrusion molding is to extrude the mixture A at a temperature of 320 - 360 °C through a screw extruder and a specific die orifice, and after extrusion, it is cooled and sized by air cooling or water cooling.

[0058] In some embodiments of the present invention, in step (5), during the turning process, a water-soluble cutting fluid is used as the coolant, and the coolant flow rate is 5 - 10 L / min.

[0059] In some embodiments of the present invention, in step (5), the surface roughness of the product C is Ra0.8 - Ra3.2 μm.

[0060] In some embodiments of the present invention, in step (6), the cleaning process is to soak the product C in an organic solvent or a special plastic cleaning agent for 10 - 30 minutes, and then rinse it thoroughly with clean water.

[0061] Example 1

[0062] This example provides a polytetrafluoroethylene sealant material, which comprises the following raw materials in parts by weight: 80 parts of modified polytetrafluoroethylene resin, 8 parts of glass fiber, 5 parts of carbon fiber, 4 parts of bronze powder, 1 part of thermosetting resin microcapsule containing furan ring, 1 part of multi-walled carbon nanotube, 4 parts of lubricant, and 2 parts of functional additive.

[0063] Furthermore, the modification method of the polytetrafluoroethylene resin comprises the following steps: putting the dried polytetrafluoroethylene resin into a sodium naphthalene solution and soaking it for 15 minutes, immediately taking it out after soaking and washing the residual sodium naphthalene solution on the surface of the polytetrafluoroethylene resin with absolute ethanol and deionized water in sequence, and drying it after washing; the drying temperature is 120 °C, and the drying time is 2 hours; the water content of the modified polytetrafluoroethylene resin is less than 0.02%.

[0064] Furthermore, the volume ratio of the polytetrafluoroethylene resin to the sodium naphthalene solution is 1:1.5.

[0065] Furthermore, the preparation method of the sodium naphthalene solution comprises the following steps: adding 550 grams of naphthalene into 1000 milliliters of tetrahydrofuran, completely dissolving it and then adding 90 grams of sodium in several portions slowly, and stirring at room temperature until the sodium is completely dissolved.

[0066] Furthermore, each part of the lubricant comprises the following raw materials in parts by weight: 2 parts of molybdenum disulfide, 1 part of graphite, and 1 part of nano boron nitride.

[0067] Furthermore, each part of the functional additive comprises the following raw materials in parts by weight: 1 part of antioxidant, 0.5 part of light stabilizer, and 0.5 part of coupling agent.

[0068] Further, the antioxidant is a phenolic antioxidant and a thioester antioxidant; the phenolic antioxidant is BHT, and the thioester antioxidant is DLTP.

[0069] Further, the weight ratio of BHT to DLTP is 2:1.

[0070] Further, the light stabilizer is light stabilizer 944.

[0071] Further, the coupling agent is a silane coupling agent and a titanate coupling agent; the silane coupling agent is KH550, and the titanate coupling agent is KR-12.

[0072] Further, the weight ratio of KH550 to KR-12 is 1:1.

[0073] Further, the length of the glass fiber is 3 - 5 mm, and the diameter is 10 - 15 μm; the length of the carbon fiber is 1 - 3 mm, and the diameter is 7 - 10 μm; the particle size of the bronze powder is less than 300 mesh; the particle size of the molybdenum disulfide is less than 400 mesh; the particle size of the graphite is less than 200 mesh; the particle size of the nano boron nitride is 50 - 100 nm; the particle size of the thermosetting resin microcapsule containing a furan ring is 1 - 100 μm; the inner diameter of the multi-walled carbon nanotube is 5 - 10 nm, the outer diameter is 10 - 20 nm, and the length is 10 - 30 μm.

[0074] Further, the weight ratio of the core material to the wall material of the thermosetting resin microcapsule containing a furan ring is 3:7. The core material is furfuryl alcohol resin, and the wall material is silica and calcium carbonate; the model of the furfuryl alcohol resin is Huilong Chemical Industry FN-4; the weight ratio of silica to calcium carbonate is 3:1.

[0075] Further, the model of the polytetrafluoroethylene resin is DuPont Teflon7A.

[0076] This embodiment also provides a manufacturing method of a polytetrafluoroethylene seal, including the following steps:

[0077] (1) Mixing: Put each raw material according to the weight parts into a high-speed mixer and mix evenly to obtain mixture A. The rotation speed of the mixer is 1500 r / min;

[0078] (2) Molding: Adopt compression molding. Keep the pressure of mixture A at 20 MPa and the temperature at 370 °C for 20 minutes to obtain blank B;

[0079] (3) Sintering: Sinter blank B at a temperature of 380 °C for 2.5 hours;

[0080] (4) Cooling: Cool the sintered blank B by natural cooling or controlling the cooling rate;

[0081] (5) Turning process: The turning speed is 300 m / min, the feed rate is 0.1 mm / r, and the cutting depth is 1 mm;

[0082] (6) Post-treatment: The product C is cleaned and inspected.

[0083] Furthermore, in step (5), a water-soluble cutting fluid is used as the coolant during the turning process, and the coolant flow rate is 10 L / min.

[0084] Furthermore, in step (5), the surface roughness of the product C is Ra 1.5 μm.

[0085] Furthermore, in step (6), the cleaning process involves soaking the product C in a special plastic cleaning agent for 10 minutes and then rinsing it thoroughly with clean water.

[0086] Example 2

[0087] This example provides a polytetrafluoroethylene sealant material, including the following raw materials in parts by weight: 90 parts of modified polytetrafluoroethylene resin, 6 parts of glass fiber, 3 parts of carbon fiber, 2 parts of bronze powder, 0.5 part of thermosetting resin microcapsule containing furan ring, 0.5 part of multi-walled carbon nanotube, 5 parts of lubricant, and 3 parts of functional additive.

[0088] Furthermore, the modification method of the polytetrafluoroethylene resin includes the following steps: Put the dried polytetrafluoroethylene resin into a sodium naphthalene solution and soak it for 20 minutes. Immediately take it out after soaking and wash the residual sodium naphthalene solution on the surface of the polytetrafluoroethylene resin with anhydrous ethanol and deionized water in turn, and dry it after washing. The drying temperature is 105 °C and the drying time is 3.5 hours; the water content of the modified polytetrafluoroethylene resin is less than 0.02%.

[0089] Furthermore, the volume ratio of the polytetrafluoroethylene resin to the sodium naphthalene solution is 1:1.2.

[0090] Furthermore, the preparation method of the sodium naphthalene solution includes the following steps: Add 450 grams of naphthalene to 900 milliliters of tetrahydrofuran, completely dissolve it, and then add 90 grams of sodium in several portions slowly and stir at room temperature until the sodium is completely dissolved.

[0091] Furthermore, each part of the lubricant includes the following raw materials in parts by weight: 1 part of molybdenum disulfide, 2 parts of graphite, and 1 part of nano boron nitride.

[0092] Furthermore, each part of the functional additive includes the following raw materials in parts by weight: 1 part of antioxidant, 0.5 part of light stabilizer, and 0.5 part of coupling agent.

[0093] Further, the antioxidant is a phenolic antioxidant and a thioester antioxidant; the phenolic antioxidant is selected as antioxidant 1010, and the thioester antioxidant is selected as DLTP.

[0094] Further, the weight ratio of antioxidant 1010 to DLTP is 1:1.

[0095] Further, the light stabilizer is light stabilizer LQ-622.

[0096] Further, the coupling agent is a silane coupling agent and a titanate coupling agent; the silane coupling agent is selected as A-151, and the titanate coupling agent is KR-12.

[0097] Further, the weight ratio of A-151 to KR-12 is 1:1.

[0098] Further, the length of the glass fiber is 3-5 mm, and the diameter is 10-15 μm; the length of the carbon fiber is 1-3 mm, and the diameter is 7-10 μm; the particle size of the bronze powder is less than 300 mesh; the particle size of the molybdenum disulfide is less than 400 mesh; the particle size of the graphite is less than 200 mesh; the particle size of the nano boron nitride is 50-100 nm; the particle size of the thermosetting resin microcapsule containing a furan ring is 1-100 μm; the inner diameter of the multi-walled carbon nanotube is 5-10 nm, the outer diameter is 10-20 nm, and the length is 10-30 μm.

[0099] Further, the weight ratio of the core material to the wall material of the thermosetting resin microcapsule containing a furan ring is 3:7. The core material is furfuryl alcohol resin, and the wall material is silica and calcium carbonate; the model of the furfuryl alcohol resin is Huilong Chemical FN-4; the weight ratio of silica to calcium carbonate is 3:1.

[0100] Further, the model of the polytetrafluoroethylene resin is Daikin Polyflo M-111.

[0101] This embodiment also provides a manufacturing method of a polytetrafluoroethylene seal, including the following steps:

[0102] (1) Mixing: Put each raw material in parts by weight into a high-speed mixer and mix evenly to obtain mixture A. The rotation speed of the mixer is 1500 r / min;

[0103] (2) Molding: Adopt extrusion molding. Extrude mixture A at a temperature of 340 °C through a screw extruder and a specific die orifice, and then cool and size it by air cooling after extrusion to obtain blank B;

[0104] (3) Sintering: Sinter blank B at a temperature of 375 °C for 3 hours;

[0105] (4) Cooling: Control the cooling rate to 10 °C / min to cool the sintered blank B.

[0106] (5) Turning: The turning speed is 200 m / min, the feed rate is 0.08 mm / r, and the cutting depth is 0.8 mm.

[0107] (6) Post-treatment: Clean and inspect the product C.

[0108] Further, in step (5), a water-soluble cutting fluid is used as the coolant during the turning process, and the coolant flow rate is 6 L / min.

[0109] Further, in step (5), the surface roughness of the product C is Ra 2.1 μm.

[0110] Further, in step (6), the cleaning process involves soaking the product C in an organic solvent for 15 minutes and then rinsing it thoroughly with clean water.

[0111] Example 3

[0112] This example provides a polytetrafluoroethylene sealant material, including the following raw materials in parts by weight: 75 parts of modified polytetrafluoroethylene resin, 10 parts of glass fiber, 6 parts of carbon fiber, 5 parts of bronze powder, 1 part of thermosetting resin microcapsule containing furan ring, 2 parts of multi-walled carbon nanotubes, 2 parts of lubricant, and 1 part of functional additive.

[0113] Further, the modification method of the polytetrafluoroethylene resin includes the following steps: Put the dried polytetrafluoroethylene resin into a sodium naphthalene solution and soak it for 25 minutes. Immediately take it out after soaking and wash the residual sodium naphthalene solution on the surface of the polytetrafluoroethylene resin with an organic solvent and deionized water in turn. After washing, dry it; the drying temperature is 115 °C and the drying time is 2.5 hours; the water content of the modified polytetrafluoroethylene resin is less than 0.02%.

[0114] Further, the volume ratio of the polytetrafluoroethylene resin to the sodium naphthalene solution is 1:2.

[0115] Further, the preparation method of the sodium naphthalene solution includes the following steps: Add 500 g of naphthalene to 1000 ml of tetrahydrofuran, completely dissolve it, and then slowly add 90 g of sodium in multiple times and stir at room temperature until the sodium is completely dissolved.

[0116] Further, each part of the lubricant includes the following raw materials in parts by weight: 1 part of molybdenum disulfide and 3 parts of nano boron nitride.

[0117] Further, each part of the functional additive includes the following raw materials in parts by weight: 1 part of antioxidant, 0.5 part of light stabilizer, and 0.5 part of coupling agent.

[0118] Further, the antioxidant is a phenolic antioxidant and a thioester antioxidant; the phenolic antioxidant is selected from BHT and antioxidant 1010, and the thioester antioxidant is selected from DLTP.

[0119] Further, the weight ratio of BHT, antioxidant 1010, and DLTP is 1:1:1.

[0120] Further, the light stabilizer is light stabilizer 944 and light stabilizer LQ-622.

[0121] The weight ratio of light stabilizer 944 and light stabilizer LQ-622 is 2:1.

[0122] Further, the coupling agent is a silane coupling agent and a titanate coupling agent. The silane coupling agent is selected from KH550 and A-151, and the titanate coupling agent is KR-12.

[0123] Further, the weight ratio of KH550, A-151, and KR-12 is 1:1:1.

[0124] Further, the length of the glass fiber is 3 - 5 mm, and the diameter is 10 - 15 μm; the length of the carbon fiber is 1 - 3 mm, and the diameter is 7 - 10 μm; the particle size of the bronze powder is less than 300 mesh; the particle size of the molybdenum disulfide is less than 400 mesh; the particle size of the graphite is less than 200 mesh; the particle size of the nano boron nitride is 50 - 100 nm; the particle size of the thermosetting resin microcapsule containing a furan ring is 1 - 100 μm; the inner diameter of the multi-walled carbon nanotube is 5 - 10 nm, the outer diameter is 10 - 20 nm, and the length is 10 - 30 μm.

[0125] Further, the weight ratio of the core material to the wall material of the thermosetting resin microcapsule containing a furan ring is 3:7. The core material is furfuryl alcohol resin, and the wall material is silica and calcium carbonate; the model of the furfuryl alcohol resin is Huilong Chemical Industry FN-4; the weight ratio of silica and calcium carbonate is 3:1.

[0126] Further, the model of the polytetrafluoroethylene resin is 3M DYNEONTF2027.

[0127] This embodiment also provides a manufacturing method of a polytetrafluoroethylene seal, including the following steps:

[0128] (1) Mixing: Input each raw material according to the weight parts into a high-speed mixer and mix evenly to obtain mixture A. The rotation speed of the mixer is 1500 r / min;

[0129] (2) Molding: Adopt compression molding. Keep the pressure of mixture A at 25 MPa and the temperature at 375 °C for 25 minutes to obtain blank B;

[0130] (3) Sintering: The blank B is sintered at a temperature of 385 °C for 2 hours;

[0131] (4) Cooling: The sintered blank B is cooled by natural cooling;

[0132] (5) Turning: The turning speed is 400 m / min, the feed rate is 0.15 mm / r, and the cutting depth is 1.5 mm;

[0133] (6) Post-treatment: The product C is cleaned and inspected.

[0134] Further, in step (5), a water-soluble cutting fluid is used as the coolant during the turning process, and the coolant flow rate is 9 L / min.

[0135] Further, in step (5), the surface roughness of the product C is Ra 1.4 μm.

[0136] Further, in step (6), the cleaning process involves soaking the product C in an organic solvent for 25 minutes and then rinsing it thoroughly with clean water.

[0137] Comparative Example 1

[0138] The difference between this comparative example and Example 1 is as follows: In this comparative example, a polytetrafluoroethylene sealant material includes the following raw materials in parts by weight: 80 parts of polytetrafluoroethylene resin, 8 parts of glass fiber, 5 parts of carbon fiber, 4 parts of bronze powder, 1 part of a thermosetting resin microcapsule containing a furan ring, 1 part of multi-walled carbon nanotubes, 4 parts of lubricant, and 2 parts of functional additives. The polytetrafluoroethylene resin is not modified by the modification method of the polytetrafluoroethylene resin in Example 1. The rest of this comparative example is the same as that of Example 1 and will not be elaborated here.

[0139] Comparative Example 2

[0140] The difference between this comparative example and Example 1 is as follows: In this comparative example, a polytetrafluoroethylene sealant material includes the following raw materials in parts by weight: 80 parts of modified polytetrafluoroethylene resin, 8 parts of glass fiber, 5 parts of carbon fiber, 4 parts of bronze powder, 4 parts of lubricant, and 2 parts of functional additives. The rest of this comparative example is the same as that of Example 1 and will not be elaborated here.

[0141] Comparative Example 3

[0142] The difference between this comparative example and Example 1 is as follows: In this comparative example, a polytetrafluoroethylene sealant material includes the following raw materials in parts by weight: 80 parts of modified polytetrafluoroethylene resin, 8 parts of glass fiber, 5 parts of carbon fiber, 4 parts of bronze powder, 4 parts of lubricant, 1 part of a thermosetting resin microcapsule containing a furan ring, and 1 part of multi-walled carbon nanotubes. The rest of this comparative example is the same as that of Example 1 and will not be elaborated here.

[0143] The performance tests were carried out on the polytetrafluoroethylene seals prepared in Examples 1-3 and Comparative Examples 1-3, and the test results are described in the following table:

[0144]

[0145] Among them, the tensile strength and elongation at break were tested according to the test method in the standard of GB / T1040.1-2018; the friction coefficient was tested according to the test method in the standard of GB / T3960-2016; the wear rate was tested according to the test method in the standard of GB / T3960-2016; the heat distortion temperature was tested according to the standard of GB / T1634.1-2019; the sealing performance was tested according to the test method in the standard of GB / T3452.1-2005.

[0146] In summary, for the polytetrafluoroethylene resin seal of the present invention, by adding raw materials such as glass fiber, carbon fiber, bronze powder, thermosetting resin microcapsules containing furan rings, multi-walled carbon nanotubes, etc. into the modified polytetrafluoroethylene resin, and adding functional aids and lubricants, the raw materials cooperate with each other, which not only fully exerts the advantages of polytetrafluoroethylene such as chemical stability and low friction coefficient, but also improves the mechanical strength, creep resistance, electrical conductivity, thermal conductivity and load-bearing capacity of the seal through fillers and functional aids. The friction coefficient is further reduced through lubricants and functional aids, and the self-lubricating performance and heat resistance are improved, which can meet the performance requirements of seals in different industrial fields and has broad application prospects.

[0147] The above specific embodiments further illustrate the technical solutions and beneficial effects of the present invention, and do not limit the implementation manners. For those skilled in the art, any obvious replacement without departing from the concept of the present invention is within the protection scope of the present invention.

Claims

1. A polytetrafluoroethylene seal, characterized in that: It includes the following raw materials in parts by weight: 70 - 99 parts of modified polytetrafluoroethylene resin, 5 - 15 parts of glass fiber, 3 - 10 parts of carbon fiber, 2 - 10 parts of bronze powder, 0.5 - 1 part of thermosetting resin microcapsule containing furan ring, 0.5 - 2 parts of multi-walled carbon nanotubes, 0 - 5 parts of lubricant, and 0 - 3 parts of functional additive.

2. The polytetrafluoroethylene seal according to claim 1, wherein: The modification method of the polytetrafluoroethylene resin includes the following steps: Put the dried polytetrafluoroethylene resin into the sodium naphthalene solution and soak for 5 - 30 minutes. Immediately take it out after soaking and wash the residual sodium naphthalene solution on the surface of the polytetrafluoroethylene resin with organic solvent and deionized water in sequence, and dry it after washing; the drying temperature is 100 - 120 °C, and the drying time is 2 - 4 hours; the water content of the modified polytetrafluoroethylene resin is less than 0.02%.

3. The polytetrafluoroethylene seal according to claim 1, characterized in that: The lubricant is at least one of molybdenum disulfide, graphite, and nano boron nitride.

4. A polytetrafluoroethylene seal according to claim 1, characterized in that: Each part of the lubricant includes the following raw materials in parts by weight: 1 - 3 parts of molybdenum disulfide, 1 - 2 parts of graphite, and 1 - 3 parts of nano boron nitride.

5. A polytetrafluoroethylene seal according to claim 1, characterized in that: Each part of the functional additive includes the following raw materials in parts by weight: 0.5 - 1.5 parts of antioxidant, 0.3 - 1 part of light stabilizer, and 0.5 - 1.5 parts of coupling agent.

6. A polytetrafluoroethylene seal according to claim 1, wherein: The length of the glass fiber is 3 - 5 mm, and the diameter is 10 - 15 μm; The length of the carbon fiber is 1 - 3 mm, and the diameter is 7 - 10 μm; The particle size of the bronze powder is less than 300 mesh; The particle size of the molybdenum disulfide is less than 400 mesh; The particle size of the graphite is less than 200 mesh; The particle size of the nano boron nitride is 50 - 100 nm; The particle size of the thermosetting resin microcapsule containing furan ring is 1 - 100 μm; The inner diameter of the multi-walled carbon nanotubes is 5 - 10 nm, the outer diameter is 10 - 20 nm, and the length is 10 - 30 μm.

7. A manufacturing method of a polytetrafluoroethylene seal as described in any one of claims 1-6, characterized in that, It includes the following steps: (1) Mixing: Put each raw material into a high-speed mixer according to parts by weight and mix evenly to obtain mixture A, and the rotation speed of the mixer is 1500 r / min; (2) Forming: Mixture A is formed by compression molding or extrusion molding to obtain blank B; (3) Sintering: Blank B is sintered at a temperature of 370 - 390 °C for 1 - 4 hours; (4) Cooling: The sintered blank B is cooled by natural cooling or controlling the cooling rate; (5) Turning: The cooled blank B is turned to obtain product C; the turning speed is 100 - 500 m / min, the feed rate is 0.05 - 0.2 mm / r, and the cutting depth is 0.5 - 2 mm; (6) Post-treatment: Product C is inspected, deburred, polished, and cleaned.

8. The manufacturing method of the polytetrafluoroethylene seal according to claim 7, characterized in that: In step (2), the compression molding is to keep the pressure of mixture A at 10 - 30 MPa and the temperature at 360 - 380 °C for 10 - 30 minutes.

9. The manufacturing method of the polytetrafluoroethylene seal according to claim 7, characterized in that: In step (2), the extrusion molding is to extrude mixture A at a temperature of 320 - 360 °C through a screw extruder and a specific die orifice, and cool and size it by air cooling or water cooling after extrusion.

10. The manufacturing method of the polytetrafluoroethylene seal according to claim 7, characterized in that: In step (5), the surface roughness of product C is Ra0.8 - Ra3.2 μm.

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