Fluororubber sealing ring with improved wear and mechanical properties and method for producing the same

Abstract

This application relates to the field of polymer sealing materials technology, and more particularly to a fluororubber sealing ring with improved wear resistance and mechanical properties, and its preparation method. The raw materials comprise the following components, by mass parts: 80-120 parts fluororubber; 5-30 parts hydrophobic silica; 2-10 parts polytetrafluoroethylene (PTFE) micropowder, wherein the PTFE micropowder has a particle size of 0.1-20 μm; 0.1-5 parts internal release agent; 0.5-4 parts accelerator; and 0.5-4 parts vulcanizing agent. This invention improves the wear resistance and mechanical properties of fluororubber by adding PTFE of a specific size. The PTFE of a specific size can delay the vulcanization time of the rubber, thus forming a suitable three-dimensional network. The rubber has sufficient strength to resist damage while maintaining good elasticity, enhancing the wear resistance of the material. The hydrophobic silica reinforces the mechanical shortcomings and effectively reduces material agglomeration. Under high-speed friction, in addition to the PTFE resisting friction, the hydrophobic silica also synergistically disperses the load, reducing volumetric wear.

Description

Technical Field

[0001] This application relates to the field of polymer sealing materials technology, and in particular to a fluororubber sealing ring with improved wear resistance and mechanical properties, and a method for preparing the same. Background Technology

[0002] Fluororubber (FKM) is a synthetic polymer elastomer in which fluorine atoms are bonded to the carbon atoms of the main chain or side chains. Due to the extremely high bond energy of the carbon-fluorine bond (approximately 485 kJ / mol) and the tight shielding protection that the fluorine atoms provide to the main chain carbon atoms, fluororubber exhibits excellent heat resistance, media resistance, aging resistance, and ozone resistance. It is widely used in sealing products under harsh operating conditions in aerospace, automotive, petrochemical, and semiconductor manufacturing industries.

[0003] However, fluororubber has relatively insufficient wear resistance, especially in dynamic sealing scenarios such as high-speed rotation and reciprocating motion. Wear-induced seal failure has become the main factor limiting the service life of fluororubber seals. At the same time, improving wear resistance often comes with a significant increase in hardness and a decrease in elasticity, resulting in a reduction in the sealing compensation capacity of the seal. This constitutes a contradiction between wear resistance and mechanical properties.

[0004] In the existing technology, the main technical routes to improve the wear resistance of fluororubber include the following: (1) Carbon black or silica (silica) reinforcement - by increasing the amount of filler, the tear resistance and wear resistance of the material can be improved, but excessive filling will lead to a sharp increase in hardness and deterioration of processing performance; (2) Fiber reinforcement - such as carbon fiber, aramid fiber, etc., to improve wear resistance by utilizing the high strength and high modulus of the fiber, but there are problems such as difficulty in fiber dispersion and poor processing fluidity; (3) Solid lubricant filling - such as graphite, molybdenum disulfide (MoS2), polytetrafluoroethylene (PTFE) micro powder, etc., to reduce surface wear by utilizing their low coefficient of friction. Among them, PTFE micro powder is considered one of the most effective wear-resistant additives due to its extremely low surface energy and coefficient of friction (the coefficient of friction is about 0.04-0.1).

[0005] Chinese patent application CN114316482A discloses a rubber polymer elastomer, which is prepared by mixing 100 parts of fluororubber and ≤20 parts of polytetrafluoroethylene through a two-stage vulcanization process on an open mill. This scheme utilizes the low friction characteristics of PTFE to improve the wear resistance of fluororubber to a certain extent. However, the single PTFE filling has the following shortcomings: (1) The interfacial bonding force between PTFE and the fluororubber matrix is ​​weak. PTFE particles are easily pulled out and detached from the matrix during friction, resulting in a decrease in long-term wear resistance; (2) The addition of PTFE will slow down the vulcanization rate and reduce the crosslinking density. Although it improves elasticity, it sacrifices mechanical properties such as tensile strength; (3) No effective reinforcing filler is introduced, and the overall mechanical properties of the material (especially tensile strength and tensile stress) are difficult to meet the requirements of high-pressure sealing conditions.

[0006] Chinese patent application CN120310163A discloses a high-sealing semiconductor sealing ring, which is prepared by using a composition of 100-120 parts perfluoroether rubber, 15-20 parts silica, and 2-6 parts polytetrafluoroethylene through open milling and two-stage vulcanization processes. This method uses both silica and PTFE, but its matrix is ​​expensive perfluoroether rubber, and it does not involve a systematic study of the influence of PTFE particle size on the performance of the fluororubber sealing ring, nor does it propose a technical approach to achieve synergistic optimization of wear resistance and mechanical properties by controlling the PTFE particle size.

[0007] Therefore, there is an urgent need in this field for a technical solution that can significantly improve the wear resistance and mechanical properties of fluororubber seals while maintaining their appropriate hardness and elasticity. Summary of the Invention

[0008] The purpose of this application is to overcome the above-mentioned shortcomings of the prior art and provide a fluororubber sealing ring with improved wear resistance and mechanical properties, and a method for preparing the same.

[0009] This application provides the following technical solution: a fluororubber sealing ring with improved wear resistance and mechanical properties, the raw material of which contains the following components, by mass parts: 80-120 parts of fluororubber; 5-30 parts of hydrophobic silica; 2-10 parts of polytetrafluoroethylene micro powder, wherein the particle size of the polytetrafluoroethylene micro powder is 0.1-20μm; 0.1-5 parts of internal release agent; 0.5-4 parts of accelerator; and 0.5-4 parts of vulcanizing agent.

[0010] In a preferred embodiment, the particle size of the polytetrafluoroethylene micro powder is 10-20 μm, more preferably 13-17 μm, and most preferably 15 μm.

[0011] The fluororubber is at least one of peroxide-based fluororubber and triazine-based fluororubber.

[0012] The hydrophobic silica is at least one of hydrophobic modified fumed silica and hydrophobic modified precipitated silica. Preferably, the amount of hydrophobic silica used is 10-20 parts, more preferably 16 parts.

[0013] The preferred internal release agent is struktol WS280 or struktol HT290.

[0014] The accelerator is used to promote the vulcanization reaction and is selected from at least one of BPP (benzyltriphenylphosphine chloride), TAIC (trimethyleneisocyanurate), and BTPPC (benzyltriphenylphosphine chloride).

[0015] The vulcanizing agent is used to initiate the crosslinking reaction of fluororubber and is selected from at least one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (commonly known as "bis-25"), triazine trithiol tetrabutylammonium salt, and 1,3-bis(tert-butylperoxyisopropyl)benzene.

[0016] This application also provides a method for preparing the above-mentioned fluororubber sealing ring, including the following steps: (1) Weigh each raw material component according to the formula requirements; (2) After drying the raw materials in step (1) at 40-60℃, add them to the open mill for mixing. The open mill temperature is 30-70℃. Mix evenly to obtain the compound. (3) The compound obtained in step (2) is vulcanized in a vulcanizing machine at a vulcanizing temperature of 150-190℃ and a vulcanizing time of 8-12min to obtain a vulcanized product. (4) The first vulcanized product obtained in step (3) is placed in a blower oven for second vulcanization. The vulcanization temperature is 200-250℃ and the vulcanization time is 8-24h to obtain the fluororubber sealing ring.

[0017] Furthermore, in step (2), the refining temperature is 45-55℃, preferably 50℃.

[0018] Furthermore, in step (3), the vulcanization temperature is 165-175℃, preferably 170℃; the vulcanization time is 9-11min, preferably 10min.

[0019] Furthermore, in step (4), the second-stage vulcanization temperature is 195-205℃, preferably 200℃; the vulcanization time is 22-24h, preferably 24h.

[0020] The beneficial effects of this application are as follows: This invention improves the wear resistance and mechanical properties of fluororubber by adding polytetrafluoroethylene (PTFE) within a specific size range. The specific size range of PTFE can delay the vulcanization time of the rubber, thus forming a suitable three-dimensional network. The rubber has sufficient strength to resist damage while maintaining good elasticity. At this point, the wear mechanism is mainly fatigue wear, energy is effectively dissipated, and wear resistance is at its highest. Both PTFE and hydrophobic silica have extremely low surface energies. Comparison of moduli shows that 15μm PTFE has the best dispersion effect. At this size, PTFE enhances the wear resistance of the material, while hydrophobic silica compensates for mechanical shortcomings, effectively reducing material agglomeration. Under high-speed friction, in addition to PTFE resisting friction, hydrophobic silica also synergistically disperses the load, reducing volumetric wear. In dynamic testing, PTFE can provide better dimensional stability, further enhancing the reinforcing effect of hydrophobic silica, thereby improving tensile strength. Attached Figure Description To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0021] Figure 1 Scanning electron microscope (SEM) images of the vulcanizates obtained in each embodiment and comparative example; Figure 2 The Fourier Transform Infrared (FTIR) spectra of PTFE micropowders with different particle sizes (P1: 15 μm, P2: 5 μm, P3: 1 μm); Figure 3 X-ray diffraction (XRD) patterns of PTFE micropowders with different particle sizes (P1-P3); Figure 4 A comparison chart showing the volumetric wear of the sealing rings obtained in each embodiment and comparative example; Figure 5 Comparison diagrams showing the compression set deformation of the sealing rings obtained in each embodiment and comparative example; Figure 6 Comparison of the mechanical properties (tensile strength, elongation at break) of the sealing rings obtained in each embodiment and comparative example: (a) stress-strain curves, (b) bar charts. Figure 7 A comparison chart of the Shore A hardness of the sealing rings obtained in each embodiment and comparative example; Figure 8 The vulcanization curves of the compound obtained in each embodiment and comparative example are shown. Figure 9The TG thermogravimetric curves (a) and DTG differential thermogravimetric curves (b) of the sealing rings obtained in each embodiment and comparative example are shown. Detailed Implementation

[0022] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application. The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0024] The main raw materials used in the following examples and comparative examples are as follows: Fluoropolymer peroxide: Grade P757, fluorine content 67%, Solvay; Hydrophobic silica: Micro-application (nano-hydrophobic fumed silica); Polytetrafluoroethylene (PTFE) micro powder: Mairuida Company selected three specifications with nominal particle sizes of 15μm (P1), 5μm (P2) and 1μm (P3); Internal release agent: HT290, Struktol; Accelerator: TAIC (tracenepropyl isocyanurate), AkzoNobel; Vulcanizing agent: 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (bis-2,5), AkzoNobel.

[0025] Comparative Example 1 (Baseline formulation without PTFE) Prepare the fluororubber sealing ring according to the following steps: S1. Weigh the raw materials: 100 parts by weight of fluoropolymer P757, 16 parts by weight of hydrophobic silica, 1 part by weight of internal release agent HT290, 2 parts by weight of accelerator TAIC, and 1 part by weight of vulcanizing agent bis(2,5)5.

[0026] S2. Mixing: The fluororubber raw material, hydrophobic silica, internal release agent, accelerator and vulcanizing agent weighed in step S1 are added to a two-roll mill for mixing in sequence. The mixing temperature is controlled at 50±5℃. After uniform mixing, the mixture is sheeted out to obtain the compound rubber.

[0027] S3, First-stage vulcanization: The compound obtained in step S2 is placed in a vacuum flat vulcanizing machine and vulcanized at 170°C and 10MPa for 10 minutes, and then pressed into a sealing ring and a test piece.

[0028] S4. Two-stage vulcanization: The sealing ring and test piece obtained in step S3 are placed in a forced-air drying oven and vulcanized at 200℃ for 24 hours. After natural cooling to room temperature, the resulting sample is recorded as M1 (comparative example).

[0029] Example 1 (15μm PTFE micro powder) S1. Weigh the raw materials: 100 parts by weight of fluoropolymer P757, 16 parts by weight of hydrophobic silica, 1 part by weight of PTFE micro powder (P1, nominal particle size 15μm), 1 part by weight of internal release agent HT290, 2 parts by weight of accelerator TAIC, and 1 part by weight of vulcanizing agent bis(2,5)5.

[0030] S2. Mixing: The fluororubber raw material, hydrophobic silica, PTFE micro powder, internal release agent, accelerator and vulcanizing agent weighed in step S1 are added to a two-roll mill for mixing in sequence. The mixing temperature is controlled at 50±5℃. After uniform mixing, the mixture is sheeted out to obtain the compound rubber.

[0031] S3, First-stage vulcanization: The compound obtained in step S2 is placed in a vacuum flat vulcanizing machine and vulcanized at 170°C and 10MPa for 10 minutes, and then pressed into a sealing ring and a test piece.

[0032] S4. Two-stage vulcanization: The sealing ring and test piece obtained in step S3 are placed in a forced-air drying oven and vulcanized at 200°C for 24 hours. After natural cooling to room temperature, the resulting sample is recorded as M2 (Example 1).

[0033] Example 2 (5μm PTFE micro powder) S1. Weigh the raw materials: 100 parts by weight of fluoropolymer P757, 16 parts by weight of hydrophobic silica, 1 part by weight of PTFE micro powder (P2, nominal particle size 5μm), 1 part by weight of internal release agent HT290, 2 parts by weight of accelerator TAIC, and 1 part by weight of vulcanizing agent bis(2,5)5.

[0034] S2. Mixing: The fluororubber raw material, hydrophobic silica, PTFE micro powder, internal release agent, accelerator and vulcanizing agent weighed in step S1 are added to a two-roll mill for mixing in sequence. The mixing temperature is controlled at 50±5℃. After uniform mixing, the mixture is sheeted out to obtain the compound rubber.

[0035] S3, First-stage vulcanization: The compound obtained in step S2 is placed in a vacuum flat vulcanizing machine and vulcanized at 170°C and 10MPa for 10 minutes, and then pressed into a sealing ring and a test piece.

[0036] S4. Two-stage vulcanization: The sealing ring and test piece obtained in step S3 are placed in a forced-air drying oven and vulcanized at 200°C for 24 hours. After natural cooling to room temperature, the resulting sample is recorded as M3 (Example 2).

[0037] Example 3 (1μm PTFE micro powder) S1. Weigh the raw materials: 100 parts by weight of fluoropolymer P757, 16 parts by weight of hydrophobic silica, 1 part by weight of PTFE micro powder (P3, nominal particle size 1μm), 1 part by weight of internal release agent HT290, 2 parts by weight of accelerator TAIC, and 1 part by weight of vulcanizing agent bis(2,5)5.

[0038] S2. Mixing: The fluororubber raw material, hydrophobic silica, PTFE micro powder, internal release agent, accelerator and vulcanizing agent weighed in step S1 are added to a two-roll mill for mixing in sequence. The mixing temperature is controlled at 50±5℃. After uniform mixing, the mixture is sheeted out to obtain the compound rubber.

[0039] S3, First-stage vulcanization: The compound obtained in step S2 is placed in a vacuum flat vulcanizing machine and vulcanized at 170°C and 10MPa for 10 minutes, and then pressed into a sealing ring and a test piece.

[0040] S4. Two-stage vulcanization: The sealing ring and test piece obtained in step S3 are placed in a forced-air drying oven and vulcanized at 200°C for 24 hours. After natural cooling to room temperature, the resulting sample is recorded as M4 (Example 3).

[0041] The samples obtained in Comparative Example 1 and Examples 1-3 were subjected to performance tests, the specific tests of which are as follows: Scanning electron microscopy (SEM) testing: The morphology of the cross-section was observed using a Thermo Fisher Nano Sem 200 scanning electron microscope. Results are as follows: Figure 1 As shown, the cross-section of Comparative Example 1 (M1) is relatively flat overall, with gently extending layered textures and very little undulation, only a few tiny protrusions, indicating poor toughness and susceptibility to brittle cracking under stress. The fracture surface roughness of Example 1 (M2, 15μm PTFE) is significantly higher than that of M1, with numerous uneven tear areas and locally bright aggregated particles, indicating that the matrix undergoes more plastic deformation under external force, and the fracture mode begins to shift from brittle to ductile. The fracture surface roughness of Example 2 (M3, 5μm PTFE) is further aggravated, with large areas of wrinkles and grooved tear morphology. The fracture surface roughness of Example 3 (M4, 1μm PTFE) is between that of M2 and M3, and long, protruding filler strips can be seen.

[0042] FTIR spectroscopy: The chemical structure of the PTFE micropowder was determined using a PerkinElmer L1230104 Fourier transform infrared spectrometer in ATR mode. Results are as follows: Figure 2 As shown, the infrared spectra of PTFE micropowders of three particle sizes (P1-P3) all exhibit the characteristic absorption peak of PTFE (~1200 cm⁻¹). -1 and ~1145 cm -1 The CF stretching vibration peak at the location indicates that PTFE micropowders of different particle sizes are chemically consistent, and the difference in particle size does not affect their basic chemical properties.

[0043] X-ray diffraction (XRD) test: The crystal structure of PTFE micropowder was tested using a Bruker D8 ADVANCE X-ray diffractometer. Results are as follows: Figure 3 As shown, the XRD patterns of PTFE micropowders of three particle sizes all exhibit characteristic diffraction peaks of PTFE (2θ≈18.1°), indicating that the PTFE micropowders maintain good crystallinity at different particle sizes. The 15μm (P1) specification has moderate diffraction peak intensity and narrow half-peak width, indicating that it has high crystallinity and uniform grain size.

[0044] Abrasion resistance test: Volumetric abrasion loss (mm³) was tested using a DIN abrasion tester according to ASTM D5963 standard. Results are as follows: Figure 4 As shown, Example 1 (M2, 15μm PTFE) had the lowest volumetric wear, which was reduced by about 14% compared to Comparative Example 1; Example 2 (M3, 5μm PTFE) was reduced by about 4%; and Example 3 (M4, 1μm PTFE) was reduced by only about 6%. The above results indicate that: (1) the introduction of PTFE micropowder can effectively improve the wear resistance of fluororubber seals; (2) the PTFE particle size has a significant impact on the wear resistance effect, and PTFE micropowder with a particle size of 15μm exhibits the best wear resistance enhancement effect.

[0045] Compression set test: According to ASTM D395 Method B, the test conditions were 200℃ × 24h, and the compression ratio was 25%. Results are as follows: Figure 5 As shown, under the test condition of 200 ℃, the compressive deformation of the M1 matrix was 24%, while the compressive deformation of samples M2, M3, and M4 after the introduction of filler decreased to 23%. The rigid filler restricts the movement of polymer chains and slightly improves the material's resistance to compressive deformation. When the temperature rises to 250 ℃, the polymer chain segments relax due to heat, and the compressive deformation of all samples increases; the compressive deformation of sample M1 is 52%, and the compressive deformation of samples M2-M4 all reach 57%, which is higher than that of the matrix material.

[0046] Tensile property testing: Tensile strength and elongation at break were tested using a universal testing machine according to ASTM D412 standard at a tensile rate of 500 mm / min. Results are as follows: Figure 6 As shown, the tensile strength of M1 was only 15.2 MPa; after adding filler, the tensile strengths of M2, M3, and M4 samples increased to 28.9 MPa, 26.4 MPa, and 25.7 MPa, respectively. Regarding elongation at break, the elongation of M2 sample decreased to 170%, the elongation of M3 sample was 182%, and the elongation of M4 was 190%.

[0047] Hardness testing: Tested using a Shore A hardness tester according to ASTM D2240 standard. Results are as follows: Figure 7 As shown, there was no significant difference in Shore A hardness among the four samples M1-M4.

[0048] Vulcanization curve test: An ALPHA RPA2000 rubber processing analyzer was used, with test conditions of 170℃ × 12 min. Results are as follows: Figure 8 As shown, the M2 sample has the lowest steady-state torque. The agglomeration of filler weakens the interaction between polymer chains, reduces melt viscosity, and improves the processing fluidity of the material.

[0049] Thermogravimetric analysis (TGA): A Beijing Instrument High-Tech ZSL-V thermogravimetric analyzer was used under a nitrogen atmosphere, with a heating rate of 10℃ / min and a test range of 30-800℃. Results are as follows: Figure 9 As shown in the TG curves, almost no thermal weight loss was observed in all samples within the 300-420 ℃ range; the polymer matrix underwent severe thermal decomposition in the 420-520 ℃ range; and the thermal decomposition process ended after 520 ℃. Compared to the pure matrix M1, the char content of the filler-modified M2-M4 samples was significantly increased.

[0050] In summary, this invention improves the wear resistance and mechanical properties of fluororubber by adding 15μm polytetrafluoroethylene (PTFE). The 15μm PTFE delays the curing time of the rubber, resulting in a suitable three-dimensional network. This allows the rubber to possess sufficient strength to resist damage while maintaining good elasticity. At this point, the wear mechanism is primarily fatigue wear, with energy effectively dissipated, resulting in the highest wear resistance. Both PTFE and hydrophobic silica have extremely low surface energies. Comparison of moduli shows that 15μm PTFE has the best dispersion effect. At this level, PTFE enhances the wear resistance of the material, while hydrophobic silica compensates for mechanical shortcomings, effectively reducing material agglomeration. Under high-speed friction, in addition to PTFE resisting friction, hydrophobic silica also synergistically disperses the load, reducing volumetric wear. In dynamic testing, PTFE provides better dimensional stability, further enhancing the reinforcing effect of hydrophobic silica, thereby improving tensile strength.

[0051] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A fluororubber seal ring having improved wear resistance and mechanical properties, characterized by, Its raw materials contain the following components, in parts by mass: 80-120 parts of fluororubber; 5-30 parts of hydrophobic silica; 0.5-10 parts of polytetrafluoroethylene (PTFE) micro powder, wherein the particle size of the PTFE micro powder is 0.1-20 μm; Internal release agent 0.1-5 parts; Accelerator 0.5-4 parts; Vulcanizing agent 0.5-4 parts.

2. The fluororubber sealing ring according to claim 1, characterized in that, The raw material comprises the following components, in parts by mass: 100 parts of fluororubber; 16 parts of hydrophobic silica; 1 part of polytetrafluoroethylene micro powder; 1 part inner mold release agent; Two parts of accelerator; 1 part vulcanizing agent.

3. The fluororubber sealing ring according to claim 1, characterized in that, The fluororubber is at least one of peroxide-based fluororubber and triazine-based fluororubber.

4. The fluororubber sealing ring according to claim 1, characterized in that, The hydrophobic silica is at least one of hydrophobic modified fumed silica and hydrophobic modified precipitated silica.

5. The fluororubber sealing ring according to claim 1, characterized in that, The particle size of the polytetrafluoroethylene micro powder is 10-20 μm.

6. The fluororubber sealing ring according to claim 1, characterized in that, The internal release agent is at least one of struktol WS280 and struktol HT290.

7. The fluororubber sealing ring according to claim 1, characterized in that, The accelerator is at least one of BPP, TAIC, and BTPPC.

8. The fluororubber sealing ring according to claim 1, characterized in that, The vulcanizing agent is at least one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, triazine trithiol tetrabutylammonium salt, and 1,3-bis(tert-butylperoxyisopropyl)benzene.

9. A method for preparing a fluororubber sealing ring according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Weigh each raw material component according to the formula requirements; (2) After drying the raw materials in step (1) at 40-60℃, add them to the open mill for mixing. The open mill temperature is 30-70℃. Mix evenly to obtain the compound. (3) The compound obtained in step (2) is vulcanized in a vulcanizing machine at a vulcanizing temperature of 150-190℃ and a vulcanizing time of 8-12min to obtain a vulcanized product. (4) The first vulcanized product obtained in step (3) is placed in a blower oven for second vulcanization. The vulcanization temperature is 200-250℃ and the vulcanization time is 8-24h to obtain the fluororubber sealing ring.

10. The preparation method according to claim 9, characterized in that, In step (2), the initial smelting temperature is 45-55℃; in step (3), the first stage vulcanization temperature is 165-175℃ and the vulcanization time is 9-11 min; in step (4), the second stage vulcanization temperature is 195-205℃ and the vulcanization time is 22-24 h.

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