A kind of EPDM rubber sealing ring and preparation method thereof

Abstract

The present application relates to the field of rubber materials, and specifically discloses an EPDM rubber seal ring and a preparation method thereof. An EPDM rubber seal ring is prepared from the following raw materials in parts by weight: 60-80 parts of EPDM rubber, 20-30 parts of silane-grafted polyurethane elastomer, 8-15 parts of carboxyl-terminated liquid nitrile rubber, 35-55 parts of filler, 10-20 parts of plasticizer, 5-10 parts of dispersant, 3-8 parts of accelerator, and 1-3 parts of vulcanizer; the silane-grafted polyurethane elastomer is prepared by reacting pentaerythritol triallyl ether, triethylene glycol diacrylate, silane coupling agent, diisocyanate and catalyst; the preparation method is: raw material mixing, sheeting, cutting; molding vulcanization molding, punching. The preparation process of the present application is simple, and the prepared EPDM rubber seal ring has a relatively moderate hardness and good compression permanent deformation, and has good sealing stability under long-term compression.

Description

Technical Field

[0001] The present application relates to the field of rubber materials, and more specifically, to an EPDM rubber sealing ring and a preparation method thereof. Background Art

[0002] EPDM is a copolymer of ethylene, propylene and a small amount of non-conjugated dienes. It is a type of ethylene-propylene rubber, represented by EPDM. It has excellent aging resistance such as ozone resistance, heat resistance, and weather resistance. It can be widely used in automotive parts, building waterproof materials, wire and cable sheaths, heat-resistant hoses, tapes, automotive seals and other fields.

[0003] When EPDM rubber is used in sealing rings, it is generally composed of EPDM rubber, carbon black filler, cross-linking agent and anti-aging agent. The amount of carbon black filler used in EPDM rubber is relatively large. The addition of carbon black filler increases the hardness of the manufactured sealing ring. When the sealing ring is under long-term sealing compression, the sealing stability performance is prone to decrease. Summary of the invention

[0004] In order to solve the problem that the sealing stability performance of the sealing ring is easily reduced when it is used in a long-term compression state, the present application provides an EPDM rubber sealing ring and a preparation method thereof.

[0005] In the first aspect, the present application provides an EPDM rubber sealing ring, which adopts the following technical solution:

[0006] An EPDM rubber sealing ring is made from the following raw materials in parts by weight:

[0007] EPDM 60-80 parts

[0008] Silane grafted polyurethane elastomer 20-30 parts

[0009] 8-15 parts of carboxyl-terminated liquid nitrile rubber

[0010] 35-55 parts of filler

[0011] Plasticizer 10-20 parts

[0012] Dispersant 5-10 parts

[0013] 3-8 parts of accelerator

[0014] 1-3 parts of vulcanizing agent;

[0015] The silane-grafted polyurethane elastomer is prepared by reacting pentaerythritol triallyl ether, triethylene glycol diacrylate, a silane coupling agent, diisocyanate and a catalyst.

[0016] By adopting the above technical scheme, EPDM rubber is a copolymer of ethylene, propylene and a small amount of non-conjugated dienes, the main chain is composed of chemically stable saturated hydrocarbons, and the side chain contains unsaturated double bonds, so it has good aging resistance and flexibility, the silane-grafted polyurethane elastomer has a good cross-linked network structure, so it has good flexibility and elasticity, and both ends of the carboxyl-terminated liquid nitrile rubber molecular chain segment have active carboxyl groups, which have good elasticity and strength. The EPDM rubber, silane-grafted polyurethane elastomer and carboxyl-terminated liquid nitrile rubber are compounded in a better amount as a rubber system, and the three produce a good synergistic effect. Under the action of a vulcanizer and an accelerator, the prepared sealing ring has relatively good flexibility and resistance to compression permanent deformation, and the filler plays a role in improving The invention relates to a novel sealing ring having a mechanical strength improving effect. However, the addition of fillers increases the hardness of the sealing ring, thereby reducing the compression permanent deformation resistance of the prepared sealing ring. The addition of a silane-grafted polyurethane elastomer prepared by pentaerythritol triallyl ether, triethylene glycol diacrylate, a silane coupling agent, a diisocyanate and a catalyst in the present application solves the problem of the hardness of the sealing ring being increased due to the addition of fillers, so that the fillers are evenly dispersed while improving the flexibility and elasticity of the sealing ring. The dispersant plays a role in further improving the vulcanization and cross-linking properties of the rubber system, further improving the flexibility and compression permanent deformation resistance of the prepared sealing ring. The sealing ring prepared by the present application is suitable for use under long-term compression and has good temperature resistance and sealing stability.

[0017] Preferably, the silane-grafted polyurethane elastomer is prepared from the following raw materials in parts by weight:

[0018] 20-40 parts of diisocyanate

[0019] Alkane coupling agent 5-8 parts

[0020] Pentaerythritol triallyl ether 5-10 parts

[0021] 3-8 parts of triethylene glycol diacrylate

[0022] 1-3 parts of catalyst.

[0023] By adopting the above technical scheme, under the action of a catalyst, diisocyanate and a silane coupling agent undergo a grafting reaction, pentaerythritol triallyl ether has a branched alkenyl structure, and triethylene glycol diacrylate has an acrylic unsaturated structure, which can undergo a further cross-linking reaction with diisocyanate, and the two have a good synergistic effect, so that a silane-grafted polyurethane elastomer with a dense interwoven network molecular structure is prepared, which has good temperature resistance and elasticity, and can further improve the flexibility and resistance to permanent compression deformation of the prepared sealing ring.

[0024] Preferably, the silane coupling agent is composed of a vinyl silane coupling agent and a long-chain alkyl silane coupling agent in a weight ratio of 1:(0.2-0.5), and the long-chain alkyl silane coupling agent is one or more of dodecyltrimethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, and hexadecyltriethoxysilane.

[0025] By adopting the above technical scheme, the long-chain alkyl silane coupling agent has a hydrophobic flexible chain segment, which can be stably dispersed and interwoven in the network molecular structure, further improving the network structure stability and density of the prepared silane-grafted polyurethane elastomer, and the long-chain alkyl silane coupling agent and the vinyl silane coupling agent with a better dosage ratio have a good synergistic effect, can stably interweave and graft with the diisocyanate system, improve the flexibility and elasticity of the prepared silane-grafted polyurethane elastomer, and further improve the compression permanent deformation resistance of the prepared sealing ring.

[0026] Preferably, the catalyst is composed of an organic tin catalyst and an organic amine catalyst in a weight ratio of (1-2):1, the organic tin catalyst is dibutyltin dilaurate and / or stannous octoate, and the organic amine catalyst is one or a combination of triethylamine, dimethylamine, and diethylenetriamine.

[0027] By adopting the above technical solution, the catalyst with a better dosage ratio can stably catalyze the grafting reaction, further improving the elasticity and molecular structure density of the prepared silane-grafted polyurethane elastomer.

[0028] Preferably, the silane-grafted polyurethane elastomer is prepared by the following steps:

[0029] A1. Add diisocyanate, pentaerythritol triallyl ether and triethylene glycol diacrylate into a reaction device, heat to 40-60° C., mix well, and obtain a mixture A;

[0030] A2. Add silane coupling agent and catalyst to mixture A, evacuate the mixture and raise the temperature to 80-95°C, react for 1-3 hours to obtain silane-grafted polyurethane elastomer.

[0031] By adopting the above technical solution, each component can stably undergo grafting reaction to prepare a silane-grafted polyurethane elastomer with stable performance.

[0032] Preferably, the filler is one or a combination of carbon black, white carbon black, calcium carbonate, talcum powder, barium sulfate and clay.

[0033] By adopting the above technical solution, the above filler is suitable for the rubber system of the present application and has a good performance reinforcement effect on the rubber system.

[0034] Preferably, the plasticizer is paraffin oil and / or naphthenic oil.

[0035] By adopting the above technical solution, the above plasticizer can improve the processing stability and fluidity of the rubber system and improve the comprehensive performance of the manufactured sealing ring.

[0036] Preferably, the dispersant consists of hydrogenated castor oil and polytrimethylene ether glycol in a weight ratio of 1:(0.2-0.8).

[0037] By adopting the above technical solution, polytrimethylene ether glycol has a helical molecular structure and is compounded with hydrogenated castor oil and used as a dispersant, which can improve the degree of vulcanization and cross-linking of the rubber system, thereby improving the flexibility and compression permanent deformation resistance of the manufactured sealing ring.

[0038] Preferably, the accelerator is one or a combination of DPTT, CBS-80, TT-80, and BZ-80, and the vulcanizing agent is S-80 and / or dipentadienyl vulcanizing agent.

[0039] By adopting the above technical solution, the above vulcanizing agent and accelerator are suitable for the rubber system of the present application, and have a relatively moderate vulcanization rate and good vulcanization efficiency.

[0040] In a second aspect, the present application provides a method for preparing an EPDM rubber sealing ring, using the following technical solution:

[0041] A method for preparing an EPDM rubber sealing ring comprises the following steps:

[0042] S1, mixing ethylene propylene diene monomer rubber, silane grafted polyurethane elastomer, carboxyl-terminated liquid nitrile rubber, filler, plasticizer and dispersant to obtain a mixed material I;

[0043] S2, after cooling to a temperature less than 90°C, adding an accelerator and a vulcanizing agent for mixing, tableting, and cutting to obtain a prefabricated sheet;

[0044] S3, molding and vulcanizing the prefabricated sheet, and punching and cutting to obtain a sealing ring.

[0045] By adopting the above technical scheme, the raw materials are firstly mixed, and then cooled after mixing and an accelerator and a vulcanizer are added. The purpose of cooling is to allow the vulcanizer and the accelerator to be stably mixed into the system without affecting the vulcanization stability of the vulcanizer and the accelerator. The raw materials are then pressed into sheets and cut into prefabricated sheets. The prefabricated sheets are vulcanized and formed. During the vulcanization forming process, the shape of the sealing ring is formed. The raw materials are then punched and the scraps are removed, so as to prepare an EPDM rubber sealing ring with stable performance.

[0046] Preferably, the mixing temperature in step S1 is 160-180°C, and the molding temperature in step S3 is 170-180°C.

[0047] By adopting the above technical scheme, the optimal mixing temperature can make the raw materials of each component mixed evenly and have good fluidity and viscosity, which is easy to carry out the subsequent processing steps; the optimal molding temperature can make the prefabricated sheet stably vulcanized and cross-linked, and prepare a sealing ring with good flexibility and resistance to permanent compression deformation.

[0048] In summary, this application has the following beneficial effects:

[0049] 1. The EPDM rubber sealing ring of the present application uses EPDM rubber, silane-grafted polyurethane elastomer and terminal carboxyl liquid nitrile rubber as the rubber system, and is compounded with fillers, dispersants, accelerators and vulcanizers, wherein the silane-grafted polyurethane elastomer is prepared by reacting pentaerythritol triallyl ether, triethylene glycol diacrylate, silane coupling agent, diisocyanate and catalyst. The silane-grafted polyurethane elastomer prepared in this way has an interwoven network molecular structure, which can improve the dispersion uniformity of the filler in the rubber system while improving the temperature resistance, flexibility and compression permanent deformation resistance of the prepared sealing ring. The EPDM rubber sealing ring prepared in this way can be used under long-term compression and has good sealing stability.

[0050] 2. By using hydrogenated castor oil and polytrimethylene ether glycol in an optimal dosage ratio, the vulcanization cross-linking degree of the rubber system can be further improved, thereby improving the flexibility and compression set resistance of the obtained sealing ring.

[0051] 3. The preparation method of the present application comprises the steps of first mixing the raw materials, cooling the mixture after mixing and adding an accelerator and a vulcanizing agent, and then pressing and cutting the raw materials into prefabricated sheets, vulcanizing the prefabricated sheets to form the shape of a sealing ring during the vulcanization molding process, and then punching and removing scraps to prepare an EPDM rubber sealing ring with stable performance. DETAILED DESCRIPTION

[0052] The present application is further described in detail below in conjunction with embodiments.

[0053] The following are the sources and specifications of some raw materials of this application. The raw materials used in the preparation examples and embodiments of this application can be obtained from the market, including but not limited to the raw materials of the following models and manufacturers. Raw materials with equivalent performance can be used:

[0054] 1. EPDM rubber: ARLANXEO 10950C;

[0055] 2. Carboxyl-terminated liquid nitrile rubber: KMIKE, CAS: 25265-19-4, nitrile rubber (CTBN);

[0056] 3. Carbon black: Cabot reinforcing carbon black N550;

[0057] 4. White carbon black: Cabot TS-530;

[0058] 5. Calcium carbonate: light calcium carbonate, 800-1250 mesh;

[0059] 6. Talc: 800-1250 mesh;

[0060] 7. Hydrogenated castor oil: BASF CO40;

[0061] 8. Polytrimethylene ether glycol: SK ECOPROL H2700 from Korea;

[0062] 9. DPTT: Dipentamethylenethiuram tetrasulfide, CAS No. 120-54-7;

[0063] 10. CBS-80: Aikem pre-dispersed masterbatch;

[0064] 11. TT-80: rubber accelerator, Shanghe Chemical, tetrabenzylthiuram disulfide;

[0065] 12. BZ-80: Rubber accelerator, Luchuan Chemical, 80% zinc di-n-butyl dithiocarbamate and 20% polymer and dispersant mixture;

[0066] 13. S-80: French MLPC S-80 vulcanizing agent.

[0067] Preparation Example of Silane Grafted Polyurethane Elastomer

[0068] Preparation Example 1

[0069] Preparation Example 1 discloses a silane-grafted polyurethane elastomer, which is prepared by the following steps:

[0070] A1. Add 6 kg of hexamethylene diisocyanate as diisocyanate, 2.4 kg of pentaerythritol triallyl ether and 0.4 kg of triethylene glycol diacrylate into a reaction kettle, heat to 40° C., mix for 30 min, and mix evenly to obtain a mixture A;

[0071] A2. Add 1 kg of vinyl trimethoxysilane as a silane coupling agent and a catalyst consisting of 0.05 kg of dibutyltin dilaurate and 0.05 kg of dimethylamine to mixture A, raise the temperature to 80° C. under a vacuum condition of -0.08 MPa, react for 1 hour, and obtain a silane-grafted polyurethane elastomer.

[0072] Preparation Example 2-3

[0073] The difference between Preparation Example 2-3 and Preparation Example 1 is that the amount of raw materials used and the preparation conditions are different, see Table 1 below for details.

[0074] Table 1 Raw material dosage and preparation conditions of Preparation Examples 1-3

[0075]

[0076]

[0077] Preparation Example 4

[0078] The difference between Preparation Example 4 and Preparation Example 2 is that the silane coupling agent is different. The silane coupling agent in Preparation Example 4 is composed of a vinyl silane coupling agent and a long-chain alkyl silane coupling agent in a weight ratio of 1:0.2. The vinyl silane coupling agent is vinyl triisopropoxy silane, and the long-chain alkyl silane coupling agent is dodecyl trimethoxy silane. The rest is the same as Preparation Example 2.

[0079] Preparation Example 5

[0080] The difference between Preparation Example 5 and Preparation Example 2 is that the silane coupling agent is composed of a vinyl silane coupling agent and a long-chain alkyl silane coupling agent in a weight ratio of 1:0.5, the vinyl silane coupling agent is vinyltrimethoxysilane, and the long-chain alkyl silane coupling agent is hexadecyltriethoxysilane, and the rest is the same as Preparation Example 2.

[0081] Preparation Comparative Example 1

[0082] The difference between Preparation Comparative Example 1 and Preparation Example 1 is that an equal amount of pentaerythritol triallyl ether is replaced by triethylene glycol diacrylate, and the rest is the same as Preparation Example 1.

[0083] Preparation Comparative Example 2

[0084] The difference between Preparation Comparative Example 2 and Preparation Example 1 is that an equal amount of triethylene glycol diacrylate is replaced by hydroxyethyl acrylate, and the rest is the same as Preparation Example 1.

[0085] Preparation Comparative Example 3

[0086] The difference between Preparation Comparative Example 3 and Preparation Example 1 is that pentaerythritol triallyl ether and triethylene glycol diacrylate are replaced by polyether triol (Arkema, TO330) in equal amounts, and the rest is the same as Preparation Example 1.

[0087] Example

[0088] Example 1

[0089] Example 1 discloses an EPDM rubber sealing ring, which is prepared by the following steps:

[0090] S1, 6 kg of EPDM rubber, 2 kg of silane-grafted polyurethane elastomer prepared in Preparation Example 1, 0.8 kg of carboxyl-terminated liquid nitrile rubber, 3.5 kg of carbon black as filler, 1 kg of 26# liquid paraffin as plasticizer and 0.5 kg of 1,4-butanediol as dispersant were mixed at a temperature of 160° C. for 1 hour to obtain a mixture I;

[0091] S2, after cooling to 89°C, add 0.3kg DPTT as an accelerator and 0.1kg dipentadienyl vulcanizer for mixing, mix for 30min, press into sheets, cut into sheets with a thickness of 3mm;

[0092] S3. Use a flat plate molding vulcanizer to perform compression molding of the preform at a molding temperature of 170° C. for 25 seconds, and then punch out to obtain a sealing ring with an outer diameter of 12.8 mm, an inner diameter of 10.6 mm, and a thickness of 0.8 mm.

[0093] Example 2-3

[0094] The difference between Example 2-3 and Example 1 is that the amount of raw materials, preparation conditions and the source of the silane-grafted polyurethane elastomer are different, see Table 2 below for details.

[0095] Table 2 Raw material dosage, preparation conditions and sources of silane grafted polyurethane elastomers of Examples 1-3

[0096]

[0097]

[0098] Example 4

[0099] The difference between Example 4 and Example 2 is that the silane-grafted polyurethane elastomer is derived from Preparation Example 4, and the rest is the same as Example 2.

[0100] Example 5

[0101] The difference between Example 5 and Example 2 is that the silane-grafted polyurethane elastomer is derived from Preparation Example 5, and the rest is the same as Example 2.

[0102] Example 6

[0103] The difference between Example 6 and Example 2 is that the dispersant consists of hydrogenated castor oil and polytrimethylene ether glycol in a weight ratio of 1:0.2, and the rest is the same as Example 2.

[0104] Example 7

[0105] The difference between Example 7 and Example 2 is that the dispersant consists of hydrogenated castor oil and polytrimethylene ether glycol in a weight ratio of 1:0.8, and the rest is the same as Example 2.

[0106] Comparative Example

[0107] Comparative Examples 1-3

[0108] The difference between Comparative Examples 1-3 and Example 1 is that the sources of the silane-grafted polyurethane elastomer are different, see Table 3 below for details.

[0109] Table 3 Sources of silane-grafted polyurethane elastomers of Comparative Examples 1-3

[0110] Comparative Example Source table of silane grafted polyurethane elastomers Comparative Example 1 Preparation Comparative Example 1 Comparative Example 2 Preparation Comparative Example 2 Comparative Example 3 Preparation Comparative Example 3

[0111] Comparative Example 4

[0112] The difference between Comparative Example 4 and Example 1 is that the dispersant is replaced by an equal amount of silane-grafted polyurethane elastomer, and the rest is the same as Example 1.

[0113] Comparative Example 5

[0114] The difference between Comparative Example 5 and Example 1 is that the silane-grafted polyurethane elastomer is replaced by an equal amount of carboxyl-terminated liquid nitrile rubber, and the rest is the same as Example 1.

[0115] Performance testing

[0116] The following is a performance test of the EPDM rubber seal rings prepared in Examples 1-7 and Comparative Examples 1-5:

[0117] (1) Hardness test

[0118] According to the test method in GB / T 531.1-2008, test the hardness (unit: Shore A) of the EPDM rubber sealing ring, and test and record the test results;

[0119] (2) Resistance to permanent compression deformation:

[0120] a) According to the test method in GB / T 1683-2018, test at room temperature (23±2℃) for 360h, and test and record the compression set rate (unit: %);

[0121] b) According to the test method in GB / T 1683-2018, test for 360 hours at a temperature of 200°C and a humidity of 85%, and test and record the compression set rate (unit: %);

[0122] The following are the performance test data of the EPDM rubber sealing rings prepared in Examples 1-7 and Comparative Examples 1-5, see Table 4 below for details.

[0123] Table 4 is a table showing the performance test data of the EPDM rubber sealing rings prepared in Examples 1-7 and Comparative Examples 1-5.

[0124]

[0125] Combining Examples 1-3 and Comparative Examples 1-3, and Comparative Example 5 and 4, it can be seen that the EPDM rubber sealing ring made using the silane-grafted polyurethane elastomer prepared in the present application has a relatively moderate hardness and a good compression deformation resistance rate; and when EPDM rubber, silane-grafted polyurethane elastomer and terminal carboxyl liquid nitrile rubber are compounded for use, a good synergistic effect can be produced, and the compression stability of the prepared EPDM rubber sealing ring is improved. In Comparative Example 5, EPDM rubber, silane-grafted polyurethane elastomer and terminal carboxyl liquid nitrile rubber are not used for compounding, and the performance of the prepared EPDM rubber sealing ring is significantly reduced; and Comparative Examples 1-3 do not use pentaerythritol triallyl ether, triethylene glycol diacrylate, silane coupling agent, diisocyanate and catalyst to prepare the silane-grafted polyurethane elastomer, and the performance of the prepared EPDM rubber sealing ring is also reduced.

[0126] It can be seen from Examples 1-3 and 4-5 and Table 4 that the silane-grafted polyurethane elastomer prepared by using a combination of a vinyl silane coupling agent and a long-chain alkyl silane coupling agent in a preferred ratio of the present application can produce an EPDM rubber with better performance.

[0127] It can be seen from Examples 1-5, Examples 6-7, Comparative Example 4 and Table 4 that the use of a preferred ratio of hydrogenated castor oil and polytrimethylene ether glycol in the present application for compounding can further improve the vulcanization crosslinking density of the prepared EPDM rubber sealing ring and improve the performance of the prepared EPDM rubber sealing ring.

[0128] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. An EPDM rubber sealing ring, characterized in that: Made from the following raw materials in parts by weight: EPDM 60-80 parts Silane grafted polyurethane elastomer 20-30 parts 8-15 parts of carboxyl-terminated liquid nitrile rubber 35-55 parts of filler Plasticizer 10-20 parts Dispersant 5-10 parts 3-8 parts of accelerator 1-3 parts of vulcanizing agent; The silane-grafted polyurethane elastomer is prepared from the following raw materials in parts by weight: 20-40 parts of diisocyanate Silane coupling agent 5-8 parts Pentaerythritol triallyl ether 5-10 parts 3-8 parts of triethylene glycol diacrylate 1-3 parts of catalyst; The silane coupling agent is composed of a vinyl silane coupling agent and a long-chain alkyl silane coupling agent in a weight ratio of 1:(0.2-0.5), and the long-chain alkyl silane coupling agent is one or more of dodecyltrimethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, and hexadecyltriethoxysilane; The silane-grafted polyurethane elastomer is prepared by the following steps: A1. Add diisocyanate, pentaerythritol triallyl ether and triethylene glycol diacrylate into a reaction device, heat to 40-60° C., mix well, and obtain a mixture A; A2, adding silane coupling agent and catalyst to mixture A, evacuating and heating to 80-95°C, reacting for 1-3h, to obtain silane-grafted polyurethane elastomer; The dispersant consists of hydrogenated castor oil and polytrimethylene ether glycol in a weight ratio of 1:(0.2-0.8).

2. The EPDM rubber sealing ring according to claim 1, characterized in that: The filler is one or a combination of carbon black, white carbon black, calcium carbonate, talcum powder, barium sulfate and clay.

3. The EPDM rubber sealing ring according to claim 1, characterized in that: The plasticizer is paraffin oil and / or naphthenic oil.

4. The EPDM rubber sealing ring according to claim 1, characterized in that: The accelerator is one or a combination of DPTT, CBS-80, TT-80, and BZ-80, and the vulcanizing agent is S-80 and / or dipentadienyl vulcanizing agent.

5. A method for preparing an EPDM rubber sealing ring according to any one of claims 1 to 4, characterized in that: The method comprises the following preparation steps: S1, mixing ethylene propylene diene monomer rubber, silane grafted polyurethane elastomer, carboxyl-terminated liquid nitrile rubber, filler, plasticizer and dispersant to obtain a mixed material I; S2, after cooling to a temperature less than 90°C, adding an accelerator and a vulcanizing agent for mixing, tableting, and cutting to obtain a prefabricated sheet; S3, molding and vulcanizing the prefabricated sheet, and punching and cutting to obtain a sealing ring.

6. The method for preparing an EPDM rubber sealing ring according to claim 5, characterized in that: The mixing temperature in step S1 is 160-180°C, and the molding temperature in step S3 is 170-180°C.

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