Plasma-resistant low-temperature-resistant combined sealing ring and preparation method thereof

Abstract

The application relates to the technical field of sealing rings, and particularly discloses a low-temperature-resistant and plasma-resistant combined sealing ring and a preparation method thereof. The combined sealing ring comprises a low-temperature-resistant rubber inner core and a corrosion-resistant rubber outer layer, the corrosion-resistant rubber outer layer is fully coated on the surface of the low-temperature-resistant rubber inner core, the glass transition temperature of the low-temperature-resistant rubber inner core is lower than-40 DEG C, the inner and outer cross section height ratio and the outer layer thickness are constrained to meet the sealing requirement of the application scene, the inner core is separately formed first, then the outer layer is injection molded and co-vulcanized with the inner core, and finally the obtained combined sealing ring not only has excellent low-temperature-resistant and plasma-resistant capacity, but also can maintain a relatively long service life in the low-temperature-normal-temperature cycle.

Description

Technical Field

[0001] This invention relates to the field of sealing ring technology, and in particular to a plasma-resistant and low-temperature-resistant combined sealing ring and its preparation method. Background Technology

[0002] Sealing rings are commonly used mechanical parts. On the one hand, they prevent fluids or solid particles from leaking between adjacent mating surfaces. On the other hand, they prevent external dust or moisture and other impurities from entering the components or materials inside the machine. In some applications of advanced semiconductor manufacturing processes, sealing rings face low-temperature and plasma corrosion working environments. These harsh working environments place high demands on the sealing ring materials, which can lead to rapid sealing ring failure. Once the sealing ring fails, it will directly reduce the environmental stability of semiconductor production, and in severe cases, it will result in batch scrap.

[0003] Perfluoroelastomer (PFE) is an elastomer material with excellent resistance to plasma and chemical media and is widely used in semiconductor applications. However, when PFE is used in sealing components, low-temperature environments can cause PFE to lose sufficient elasticity, leading to seal failure. If low-temperature resistant rubber is directly applied to sealing components, the low-temperature resistant elastomer is difficult to resist plasma corrosion.

[0004] Currently, there is an urgent need to develop a composite sealing ring that is resistant to plasma and low temperatures. Summary of the Invention

[0005] To address the technical problems existing in the background art, the present invention proposes a plasma-resistant and low-temperature resistant combined sealing ring, the combined sealing ring comprising a low-temperature resistant rubber inner core and a corrosion-resistant rubber outer layer, wherein the corrosion-resistant rubber outer layer fully covers the surface of the low-temperature resistant rubber inner core; the glass transition temperature of the low-temperature resistant rubber inner core is below -40℃.

[0006] On the same cross section perpendicular to the sealing surface, the cross section height of the low-temperature rubber inner core is B, and the cross section height of the combined sealing ring is A. A / B=5 / 3, (AB) / 2=0.3-3mm.

[0007] In this invention, the glass transition temperature of the elastic core is below -40°C. Therefore, the elastic core maintains high elasticity and high resilience when working at low temperatures. When A / B=5 / 3 and (AB) / 2=0.3-3mm, the deformation stress of the corrosion-resistant rubber outer layer is small. It is not easy to crack and fail after being reduced from constant pressure at room temperature to the applied low temperature. The elastic inner core provides continuous pressure to the sealing surface and can maintain sufficient rebound force on the corrosion-resistant rubber outer layer under the applied low temperature conditions. This prevents the corrosion-resistant rubber outer layer from creating micro-gap leakage channels at the interface with the contact component under pressure, thereby meeting the sealing requirements.

[0008] Preferably, the low-temperature resistant rubber core is any one of silicone rubber, EPDM rubber, nitrile rubber, hydrogenated nitrile rubber, fluororubber, or fluorosilicone rubber.

[0009] Preferably, the corrosion-resistant rubber outer layer is perfluoroether rubber.

[0010] Preferably, a transition layer is further included between the low-temperature resistant rubber inner core and the corrosion-resistant rubber outer layer.

[0011] Preferably, the transition layer is achieved by chemical bonding between the low-temperature resistant rubber inner core and the corrosion-resistant rubber outer layer through a silane coupling agent containing polysulfide groups and unsaturated carbon-carbon double bonds.

[0012] In this invention, the transition layer connects the low-temperature resistant rubber inner core and the corrosion-resistant rubber outer layer. On the one hand, the transition layer has a certain "stress relaxation" capability, reducing the generation of microcracks; on the other hand, when the sealing rubber ring returns to room temperature, the polysulfide bonds in the transition layer can dynamically repair microcracks, significantly extending service life. Simultaneously, the transition layer can also mitigate the risks of separation between the inner and outer layers, and outer layer cracking, caused by differences in shrinkage rates due to the different materials of the inner and outer layers under temperature changes.

[0013] The present invention also proposes a method for preparing the above-mentioned plasma-resistant and low-temperature-resistant combined sealing ring, the method comprising the following steps: S1. Low-temperature resistant rubber inner core compound and corrosion-resistant rubber outer layer compound are obtained respectively; S2. The low-temperature resistant rubber inner core is obtained by vulcanizing the low-temperature resistant rubber inner core compound and then surface treating it. S3. Place the low-temperature resistant rubber inner core into the mold cavity, inject the corrosion-resistant rubber outer layer compound to form a composite elastomer, and vulcanize the composite elastomer to obtain the combined sealing ring.

[0014] Preferably, the surface treatment includes sandblasting the surface of the low-temperature resistant rubber core.

[0015] In this invention, the sandblasting step can increase the surface roughness of the low-temperature resistant rubber core, increase the contact area between the two rubber layers, and thus increase the connection strength at the interface.

[0016] Preferably, the low-temperature resistant rubber core compound comprises low-temperature resistant rubber raw rubber, silica, structure control agent, vulcanizing agent, crosslinking agent, and release agent; the corrosion-resistant rubber outer layer compound comprises perfluoroether rubber raw rubber, silica, crosslinking agent, and vulcanizing agent.

[0017] Preferably, the corrosion-resistant rubber outer compound further includes a silane coupling agent containing polysulfide groups and unsaturated carbon-carbon double bonds.

[0018] Preferably, the surface treatment further includes grafting mercaptosilane onto the surface of the low-temperature resistant rubber core after sandblasting.

[0019] In this invention, the mercapto-containing silane grafted onto the surface of the low-temperature resistant rubber core allows the surface of the low-temperature resistant rubber core to be coated with mercapto groups. The mercapto groups and the unsaturated carbon-carbon double bonds in the coupling agent undergo a mercapto-alkene click chemical reaction at the vulcanization temperature. The coupling agent achieves a strong chemical bond on both sides of the rubber. The coupling agent forms a transition layer containing polysulfide bonds at the interface of the two rubber layers, which significantly extends the service life of the combined sealing ring.

[0020] Beneficial effects of this invention: (1) By constraining the size ratio, the outer layer is not easily brittle at low temperatures, and the inner core continues to provide elasticity. The resulting combined sealing ring can maintain good sealing performance in low-temperature corrosive environments. (2) When a transition layer containing polysulfide bonds is formed at the interface, the service life of the combined sealing ring during low-temperature to room-temperature cycling is significantly increased. Attached Figure Description

[0021] Figure 1 This is a cross-sectional schematic diagram of the combined sealing ring in Example 1; Figure 2 This is a cross-sectional schematic diagram of the combined sealing ring in Example 2; Figure 3 This is a cross-sectional schematic diagram of the combined sealing ring in Example 3. Detailed Implementation

[0022] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[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 invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0024] The technical solution of the present invention will now be described more clearly and completely with reference to specific embodiments and comparative examples.

[0025] Example 1 This embodiment proposes a plasma-resistant and low-temperature-resistant combined sealing ring, the preparation method of which includes the following steps: (1) Preparation of fluorosilicone compound (FVMQ) and perfluoroether compound (FFKM): The preparation methods are as follows, and the parts in the following preparation methods are all by weight: 100 parts of fluorosilicone rubber raw rubber, 20 parts of filler silica, 3.5 parts of structure control agent hydroxyl fluorosilicone oil, 2 parts of vulcanizing agent 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 3 parts of triallyl isocyanurate (TAIC), and 0.8 parts of mold release agent zinc stearate were placed in a two-roll mill and mixed at 35°C for 20 minutes to obtain fluorosilicone compound. 100 parts of perfluoroether raw rubber, 15 parts of silica, 2.5 parts of vulcanizing agent 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, and 3 parts of triallyl isocyanurate (TAIC) were placed in a two-roll mill and mixed at 50°C to obtain perfluoroether compound. (2) The fluorosilicone compound is placed in the sealing ring mold of the flat vulcanizing machine and vulcanized for the first time to obtain an O-ring with a wire diameter of 2.118 mm and an inner diameter of 26.402 mm. The surface of the O-ring is then sandblasted and cleaned with ethanol to obtain a rough O-ring. The first vulcanization temperature is 175℃ and the first vulcanization time is 15 min. (3) Place the rough O-ring in the O-ring injection molding mold cavity and inject perfluoroether compound with a thickness of 0.706 mm on its upper and lower surfaces respectively to form a composite elastomer. Place the composite elastomer in an oven for a second vulcanization to obtain the combined sealing ring. The second vulcanization temperature is 230℃. The second vulcanization is to raise the temperature to the predetermined temperature and keep it at the temperature for 16 hours.

[0026] The cross-section of the combined sealing ring obtained in Example 1 is as follows: Figure 1 As shown, they are concentric circles, where A / B = (2.118 + 2 × 0.706) / 2.118 = 5 / 3. When the combined sealing ring is installed on the sealing assembly, any convex surface can be used as the sealing direction / groove installation direction.

[0027] Example 2 This embodiment proposes a plasma-resistant and low-temperature-resistant combined sealing ring, the preparation method of which includes the following steps: (1) Preparation of fluorosilicone compound (FVMQ) and perfluoroether compound (FFKM): The preparation methods are as follows, and the parts in the following preparation methods are all by weight: 100 parts of fluorosilicone rubber raw rubber, 35 parts of filler silica, 6 parts of structure control agent hydroxyl fluorosilicone oil, 2 parts of vulcanizing agent 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 3 parts of triallyl isocyanurate (TAIC), and 1 part of mold release agent zinc stearate were placed in a two-roll mill and mixed at 40°C for 30 minutes to obtain fluorosilicone compound. 100 parts of perfluoroether raw rubber, 10 parts of silica, 2.5 parts of vulcanizing agent 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, and 3 parts of triallyl isocyanurate (TAIC) were placed in a two-roll mill and mixed at 50°C to obtain perfluoroether compound. (2) The fluorosilicone compound is placed in the sealing ring mold of the flat vulcanizing machine and vulcanized for the first time to obtain an O-ring with a wire diameter of 2.118 mm and an inner diameter of 26.402 mm. The surface of the O-ring is then sandblasted and cleaned with ethanol to obtain a rough O-ring. The first vulcanization temperature is 185℃ and the first vulcanization time is 15 min. (3) Place the rough O-ring in the O-ring injection molding mold cavity and inject perfluoroether compound with a thickness of 0.706 mm on its upper and lower surfaces respectively to form a composite elastomer. Place the composite elastomer in an oven for a second vulcanization to obtain the combined sealing ring. The second vulcanization temperature is 200℃ and the second vulcanization time is 16h.

[0028] The cross-section of the combined sealing ring obtained in Example 2 is as follows Figure 2 As shown, it is a D-shaped structure with a semicircle and a straight edge, where the semicircular side is the sealing direction and the straight edge is the groove installation direction.

[0029] Example 3 This embodiment proposes a plasma-resistant and low-temperature-resistant combined sealing ring, the preparation method of which includes the following steps: (1) Preparation of fluorosilicone compound (FVMQ) and perfluoroether compound (FFKM): The preparation methods are as follows, and the parts in the following preparation methods are all by weight: 100 parts of fluorosilicone rubber raw rubber, 10 parts of filler silica, 2 parts of structure control agent hydroxyl fluorosilicone oil, 1 part of vulcanizing agent 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1.5 parts of triallyl isocyanurate (TAIC), and 0.5 parts of mold release agent zinc stearate were placed in a two-roll mill and mixed at 40°C for 15 minutes to obtain fluorosilicone compound. 100 parts of perfluoroether raw rubber, 15 parts of silica, 2.5 parts of vulcanizing agent 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, and 3 parts of triallyl isocyanurate (TAIC) were placed in a two-roll mill and mixed at 50°C to obtain perfluoroether compound. (2) The fluorosilicone compound is placed in the sealing ring mold of the flat vulcanizing machine and vulcanized for the first time to obtain an O-ring with a wire diameter of 2.118 mm and an inner diameter of 26.402 mm. The surface of the O-ring is then sandblasted and cleaned with ethanol to obtain a rough O-ring. The first vulcanization temperature is 170℃ and the first vulcanization time is 20 min. (3) Place the rough O-ring in the O-ring injection molding mold cavity and inject perfluoroether compound with a thickness of 0.706 mm on its upper and lower surfaces respectively to form a composite elastomer. Place the composite elastomer in an oven for a second vulcanization to obtain the combined sealing ring. The second vulcanization temperature is 230℃ and the second vulcanization time is 10h.

[0030] The cross-section of the combined sealing ring obtained in Example 3 is as follows: Figure 3 As shown, this is a D-shaped structure with a semicircular and wavy toothed edge, where the semicircular side is the groove mounting direction and the wavy toothed edge is the sealing direction.

[0031] Example 4 This embodiment proposes a plasma-resistant and low-temperature-resistant combined sealing ring, the preparation method of which includes the following steps: (1) Preparation of fluorosilicone compound (FVMQ) and perfluoroether compound (FFKM): The preparation methods are as follows, and the parts in the following preparation methods are all by weight: 100 parts of fluorosilicone rubber raw rubber, 20 parts of filler silica, 3.5 parts of structure control agent hydroxyl fluorosilicone oil, 1.5 parts of vulcanizing agent 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 3 parts of triallyl isocyanurate (TAIC), and 0.8 parts of mold release agent zinc stearate were placed in a two-roll mill and mixed at 35°C for 20 minutes to obtain fluorosilicone compound. 100 parts of perfluoroether raw rubber, 15 parts of silica, 2 parts of silane coupling agent containing polysulfide groups and unsaturated carbon-carbon double bonds, 3 parts of vulcanizing agent 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, and 3 parts of triallyl isocyanurate (TAIC) were placed in a two-roll mill and mixed at 50°C to obtain perfluoroether compound. The silane coupling agent containing polysulfide groups and unsaturated carbon-carbon double bonds is synthesized through the following steps: The raw materials were weighed according to the molar ratio of bis-(γ-triethoxysilylpropyl)tetrasulfide:polyethylene glycol monoallyl ether = 1:4. The two were put into a three-necked flask, and then 0.3 wt% of the catalyst tetrabutyl titanate was added. Under nitrogen protection, the mixture was stirred at 90°C for 3 hours and then rotary evaporated to obtain the product. The ethoxy group in bis-(γ-triethoxysilylpropyl)tetrasulfide was replaced by polyethylene glycol monoallyl ether through transesterification to obtain a silane coupling agent containing polysulfide groups and unsaturated carbon-carbon double bonds. (2) The fluorosilicone compound was placed in the sealing ring mold of the flat vulcanizing machine for the first vulcanization to obtain an O-ring with a wire diameter of 2.118 mm and an inner diameter of 26.402 mm. The surface of the O-ring was then sandblasted and cleaned with ethanol. The cleaned O-ring was then immersed in a modifying solution (15 wt% mercaptopropyltrimethoxysilane, 50 wt% ethanol, and 35 wt% deionized water). The immersed O-ring was then dried and cured at 80 °C for 60 min to obtain a rough O-ring with grafted mercapto groups. The first vulcanization temperature is 175℃, and the first vulcanization time is 15 minutes; (3) Place the O-ring in the O-ring injection molding mold cavity and inject perfluoroether compound with a thickness of 0.706mm on its upper and lower surfaces respectively to form a composite elastomer. Place the composite elastomer in an oven for a second vulcanization to obtain the combined sealing ring. The second vulcanization temperature is 220℃ and the second vulcanization time is 12h.

[0032] The cross-section of the combined sealing ring obtained in Example 4 is as follows Figure 1 As shown, during the second vulcanization, on the perfluoroether rubber side, the coupling agent forms stable siloxane bonds with the hydroxyl groups on the surface of silica; on the silicone fluororubber side, the thiol groups on the surface of the O-ring undergo a thiol-alkene click chemical reaction with the double bonds in the coupling agent, forming stable thioether bonds. That is, the coupling agent achieves strong chemical bonding on both sides of the rubber. The coupling agent forms a transition layer containing polysulfide bonds at the interface of the two rubber layers. On the one hand, the transition layer has a certain "stress relaxation" ability, reducing the generation of microcracks; on the other hand, when the sealing rubber ring returns to room temperature, the polysulfide bonds in the transition layer can also dynamically repair microcracks; in addition, the long side chains of the coupling agent can also undergo chain entanglement at the interface, providing a certain physical bond at the interface. The resulting transition layer can significantly extend the service life of the combined sealing ring.

[0033] Comparative Example 1 This comparative example proposes a sealing rubber ring, the preparation method of which is the same as that of Example 1, except that step (3) "perfluoroether compound" is replaced with "fluorosilicone compound".

[0034] In Comparative Example 1, the final size of the sealing rubber ring is the same as that in Example 1, except that the inner core and outer layer of the sealing rubber ring obtained in Comparative Example 1 are all composed of fluorosilicone rubber.

[0035] Comparative Example 2 This comparative example proposes a sealing rubber ring, which is prepared in the same way as in Example 1, except that the “fluorosilicone compound” in step (2) is replaced with “perfluoroether compound”.

[0036] In Comparative Example 2, the final size of the sealing rubber ring is the same as that in Example 1, except that the inner core and outer layer of the sealing rubber ring obtained in Comparative Example 2 are all composed of perfluoroether rubber.

[0037] Comparative Example 3 This comparative example proposes a sealing rubber ring, which is prepared in the same way as in Example 1, except that in step (2), "obtaining an O-ring with a wire diameter of 2.118 mm and an inner diameter of 26.402 mm" is replaced with "obtaining an O-ring with a wire diameter of 3.12 mm and an inner diameter of 13.406 mm"; and "injecting a 0.706 mm thick perfluoroether compound on its upper and lower surfaces" is replaced with "injecting a 0.205 mm thick perfluoroether compound on its upper and lower surfaces".

[0038] In Comparative Example 3, although the bus diameter of the combined rubber ring remains the same as in Example 1, the reduction in the thickness of the outer layer of the rubber ring causes the outer layer of the sealing rubber ring to crack and separate from the inner core when the temperature is reduced to the operating temperature, resulting in a significant decrease in the performance of the sealing rubber ring. In addition, the reduced molding thickness of the outer layer also significantly increases the processing difficulty, which has an adverse effect on production stability and economy.

[0039] Comparative Example 4 This comparative example proposes a sealing rubber ring, which is prepared in the same way as in Example 4, except that the phrase “weigh the raw materials according to the molar ratio of bis-(γ-triethoxysilylpropyl)tetrasulfide:polyethylene glycol monoallyl ether = 1:4” in step (1) is replaced with “weigh the raw materials according to the molar ratio of bis-(γ-triethoxysilylpropyl)tetrasulfide:polyethylene glycol monomethyl ether = 1:4”.

[0040] In Comparative Example 4, because the reactants for transesterification changed, the coupling agent obtained in the end did not have a reactive carbon-carbon double bond. Therefore, during the second vulcanization, the coupling agent in Comparative Example 4 could not form a click chemical bond with the thiol groups on the inner core surface and could not form an effective transition layer at the interface. On the contrary, because thiol groups themselves have strong reactivity, the free thiol groups will undergo a rapid cross-linking reaction with the vulcanizing agent or the unsaturated structure in the rubber, interfering with the normal vulcanization process and forming an interface layer with uneven local cross-linking density. This makes it easier to generate microcracks, ultimately leading to a rapid decline in product performance. That is, the service life of Comparative Example 4 was 5-10% lower than that of Example 4, and significantly lower than that of Example 4 by about 20%.

[0041] The sealing rubber rings obtained in Examples 1-4 and Comparative Examples 1-4 were used as samples for performance testing. Plasma tolerance: The samples of each example and comparative example were continuously irradiated for 30 hours under a plasma of 550W, 50sccmNF3 + 30sccmN2, and the weight change (weight loss, wt%) before and after irradiation was measured. Low-temperature performance: In an adjustable-temperature helium detector, each O-ring was compressed at 25% and evacuated at room temperature for 20 minutes. After the displayed helium leakage rate stabilized, the temperature was gradually lowered to -80℃. If the helium leakage rate increased sharply at a certain temperature, that temperature was determined to be the leakage temperature of the O-ring. Low-temperature compression permanent deformation: Each example of sealing ring was placed in an environment of -60℃ for 168 hours with a compression rate of 25%, and then removed and restored to room temperature. The thickness change was measured and the ratio of the thickness reduction to the original thickness was calculated. The results of the three tests are detailed in Table 1.

[0042] Table 1 Performance test results of each embodiment and comparative example Due to the thinning of the outer layer, it detaches from the inner layer at -20℃ and is then fractured, causing leakage.

[0043] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A low temperature resistant, plasma resistant, combined sealing ring, characterized in that The combined sealing ring includes a low-temperature resistant rubber inner core and a corrosion-resistant rubber outer layer, wherein the corrosion-resistant rubber outer layer completely covers the surface of the low-temperature resistant rubber inner core; the glass transition temperature of the low-temperature resistant rubber inner core is below -40°C. On the same cross section perpendicular to the sealing surface, the cross section height of the low-temperature resistant rubber inner core is B, and the cross section height of the combined sealing ring is A. A / B=5 / 3, (AB) / 2=0.3-3mm; The low-temperature resistant rubber core is any one of silicone rubber, EPDM rubber, nitrile rubber, fluororubber, or fluorosilicone rubber; the corrosion-resistant rubber outer layer is perfluoroether rubber. A transition layer is also included between the low-temperature resistant rubber inner core and the corrosion-resistant rubber outer layer; The transition layer is achieved through chemical bonding between the low-temperature resistant rubber inner core and the corrosion-resistant rubber outer layer by a silane coupling agent containing polysulfide groups and unsaturated carbon-carbon double bonds.

2. A method for preparing the plasma-resistant and low-temperature-resistant combined sealing ring as described in claim 1, characterized in that, The preparation method includes the following steps: S1. Low-temperature resistant rubber inner core compound and corrosion-resistant rubber outer layer compound are obtained respectively; S2. The low-temperature resistant rubber inner core is obtained by vulcanizing the low-temperature resistant rubber inner core compound and then surface treating it. S3. Place the low-temperature resistant rubber inner core into the mold cavity, inject the corrosion-resistant rubber outer layer compound to form a composite elastomer, and vulcanize the composite elastomer to obtain the combined sealing ring.

3. The method for preparing the plasma-resistant and low-temperature-resistant combined sealing ring according to claim 2, characterized in that, The surface treatment includes sandblasting the surface of the low-temperature resistant rubber core.

4. The method for preparing the plasma-resistant and low-temperature-resistant combined sealing ring according to claim 2, characterized in that, The low-temperature resistant rubber core compound includes low-temperature resistant rubber raw rubber, silica, structure control agent, vulcanizing agent, crosslinking agent, and release agent; the corrosion-resistant rubber outer layer compound includes perfluoroether rubber raw rubber, silica, crosslinking agent, and vulcanizing agent.

5. The method for preparing the plasma-resistant and low-temperature-resistant combined sealing ring according to claim 4, characterized in that, The corrosion-resistant rubber outer compound also includes a silane coupling agent containing polysulfide groups and unsaturated carbon-carbon double bonds.

6. The method for preparing the plasma-resistant and low-temperature-resistant combined sealing ring according to claim 3, characterized in that, The surface treatment also includes grafting mercaptosilanes onto the surface of the low-temperature resistant rubber core after sandblasting.

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