Ethylene-propylene-diene monomer rubber for low-voltage-change color environment-friendly O-shaped ring and preparation method thereof

Abstract

The invention discloses an ethylene propylene diene monomer for a low-pressure-change color environment-friendly O-shaped ring and a preparation method of the ethylene propylene diene monomer, and belongs to the technical field of ethylene propylene diene monomer, the ethylene propylene diene monomer for the low-pressure-change color environment-friendly O-shaped ring comprises the following components: a reinforcing agent, a plasticizer, an active agent, g-C3N4 / shell powder composite particles, a modified vulcanizing agent, a coloring agent and ethylene propylene diene monomer. According to the invention, the hydroxypropyl methylcellulose acetate succinate is introduced, so that the endurance capacity of the O-shaped ring under an extremely low temperature condition is remarkably enhanced, the application range of the O-shaped ring is widened, and the O-shaped ring can keep stable performance in a severe environment. And g-C3N4 / shell powder composite particles are ingeniously fused, so that the compression deformation rate of the material in a high-temperature environment is greatly reduced, and the recovery capability of the material after deformation is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of ethylene propylene diene monomer rubber, and in particular to ethylene propylene diene monomer rubber for low-pressure color-changing environmentally friendly O-rings and a preparation method thereof. Background Art

[0002] O-rings are suitable for assembly on various precision mechanical equipment, and they play a sealing role in a static or moving state at specified temperatures, pressures, and in different liquid and gas media. Various types of sealing elements are widely used in industrial machinery such as machine tools, ships, automobiles, aerospace, metallurgical machinery, chemical machinery, construction machinery, agricultural machinery, and various instruments and meters. O-rings are mainly used for static sealing and reciprocating motion sealing. When used for rotary motion sealing, they are limited to low-speed rotary sealing devices. O-rings are generally installed in grooves with rectangular outer or inner cross-sections to play a sealing role. O-rings still play a good sealing and shock-absorbing role in environments such as oil resistance, acid and alkali resistance, abrasion, and chemical erosion. Therefore, O-rings are the most widely used seals in hydraulic and pneumatic transmission systems.

[0003] For example, Chinese patent CN115678171B discloses a method for preparing an ultra-low cold-resistant EPDM rubber seal ring, which specifically comprises: using silicone oil grafted EPDM, modified sodium montmorillonite and commercialized EPDM in combination. On this basis, compound paraffin oil, vulcanizing agent, accelerator, etc., after mixing and vulcanization, the product can be obtained. The organosilicon-modified EPDM used in the present invention can significantly improve the cold resistance and has good compatibility with EPDM; adding organic montmorillonite improves the process performance of the rubber compound, and using environmentally friendly compounding agents reduces its toxic side effects and pollution to the environment.

[0004] Although the above patent improves the cold resistance, it cannot maintain a small compression deformation rate at high temperature, that is, the recovery still needs to be improved.

[0005] Based on this, the present invention designs an EPDM rubber for a low-pressure color-changing environmentally friendly O-ring and a preparation method thereof to solve the above-mentioned problems. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, the present invention provides an EPDM rubber for a low-pressure color-changing environmentally friendly O-ring and a preparation method thereof.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] A low-pressure color-changing environmentally friendly EPDM rubber for O-rings, comprising the following components:

[0009] 35-40 parts of reinforcing agent;

[0010] 8-10 parts of plasticizer;

[0011] 3.6-4.2 parts of active agent;

[0012] C 3 N 4 / shell powder composite particles 1.9-2.3 parts;

[0013] 3.8-5.3 parts of modified vulcanizing agent;

[0014] Colorant 2.7-5.8 parts;

[0015] 45-58 parts of EPDM rubber;

[0016] The modified vulcanizing agent contains a vulcanizing agent, hydroxypropyl methylcellulose acetate succinate, potassium silicate and chitosan in a mass ratio of 25-36:3-6:5-8:15-18.

[0017] A method for preparing EPDM rubber for low-pressure color-changing environmentally friendly O-rings comprises the following steps:

[0018] Step 1: preparing a modified vulcanizing agent;

[0019] A. Put a vulcanizing agent into water to prepare a suspension; heat the suspension to 75-80° C., and add molten hydroxypropyl methylcellulose acetate succinate to the suspension to obtain a mixture A;

[0020] B. Adjust the pH of the potassium silicate solution to 9-10, add chitosan to react, and then adjust the pH to 3-4 to degrade the chitosan and precipitate modified silicon dioxide in the solution; centrifuge to obtain the solid, and dry to obtain solid B;

[0021] C. Add solid B into mixture A, disperse evenly and keep warm at 70-75°C for 10-15 minutes to obtain a modified vulcanizing agent;

[0022] Step 2: preparing a modified active agent;

[0023] Preheat the active agent to 42-53°C, add 1 / 4-1 / 3 of gC 3 N 4 / shell powder composite particles, stir, and raise the temperature by 3-15℃ while stirring; add 1 / 4-1 / 3 gC 3 N 4 / shell powder composite particles, stir; add the remaining gC 3 N 4 / shell powder composite particles, stirring, and heating to 80-82°C while stirring to obtain a modified active agent;

[0024] Step 3: Take 30-40% of the total amount of the reinforcing agent, calcine it and grind it into powder; mix the remaining reinforcing agent and plasticizer evenly to obtain a mixture C;

[0025] Step 4: Put the EPDM rubber and the calcined reinforcing agent into an internal mixer, mix them at 130-142°C, lift the hammer and clean them; put the colorant, mixture C, modified activator and modified vulcanizer into the internal mixer, mix them at 145-162°C, unload the materials and flake them to obtain the EPDM rubber for low-pressure color-changing environmentally friendly O-rings.

[0026] Furthermore, step A is specifically as follows: adding a vulcanizing agent into water at 45-60° C. to prepare a suspension; heating the suspension to 75-80° C. at a rate of 10-15° C. / min, and adding molten hydroxypropyl methylcellulose acetate succinate to the suspension to obtain a mixture A.

[0027] Furthermore, step B is specifically as follows: adjusting the pH of a 38-42% potassium silicate solution to 9-10, adding chitosan to react for 20-30 minutes, and then adjusting the pH to 3-4 to degrade the chitosan and precipitate modified silicon dioxide in the solution; centrifuging to obtain a solid, and drying to obtain solid B.

[0028] Furthermore, in step B, the mass ratio of hydroxypropyl methylcellulose acetate succinate, potassium silicate and chitosan is 3-6:5-8:15-18.

[0029] Furthermore, step 2 is as follows: preheat the active agent to 42-53°C, add 1 / 4-1 / 3 of gC 3 N 4 / shell powder composite particles, stir at a speed of 200-300r / min for 15-20min, while stirring, heating at a speed of 3-5℃ / min to 3-15℃; add 1 / 4-1 / 3 of gC 3 N 4 / shell powder composite particles, stir at a speed of 200-300r / min for 15-20min, keep warm for 5-8min; add the remaining gC 3 N 4 / shell powder composite particles, stirring at a speed of 200-300r / min for 15-20min, heating to 80-82°C at a speed of 3-5°C / min while stirring to obtain a modified active agent.

[0030] Furthermore, step three is specifically as follows: 30-40% of the total amount of the reinforcing agent is calcined at 800-900° C. for 2-3 hours and then ground into powder; the remaining reinforcing agent is evenly mixed with the plasticizer to obtain a mixture C.

[0031] Furthermore, step four is specifically as follows: putting the EPDM rubber and the calcined reinforcing agent into an internal mixer, mixing them at 130-142°C, lifting the hammer and cleaning, putting the colorant, mixture C, modified activator and modified vulcanizer into the internal mixer, mixing them at 145-162°C, and then unloading the material to obtain low-pressure color-changing environmentally friendly O-ring EPDM rubber.

[0032] Furthermore, the reinforcing agent is a mixture of precipitated silica VN3 and dry-calcined kaolin in a mass ratio of 3-4:2-5.

[0033] Furthermore, the active agent is liquid polyethylene glycol with a molecular weight of 300-400.

[0034] Compared with the prior art, the present invention has the following beneficial effects: 1. The Shore hardness of the EPDM rubber for the low-pressure color-changing environmentally friendly O-ring prepared by the present invention is precisely controlled within the range of 65 to 75, ensuring excellent durability and sealing performance. The tensile strength is not less than 8MPa, and the elongation at break is as high as more than 200%. All mechanical properties far exceed the industry standards, demonstrating excellent physical properties and stability.

[0035] 2. The present invention introduces hydroxypropyl methylcellulose acetate succinate through scientific proportioning, which significantly enhances the tolerance of the O-ring under extreme low temperature conditions, broadens its application range, and enables it to maintain stable performance even in harsh environments.

[0036] 3. In addition, the present invention also cleverly integrates gC 3 N 4 / Shell powder composite particles, this innovative combination not only greatly reduces the compression deformation rate of the material in high temperature environment, but also improves its recovery ability after deformation, ensuring the long-lasting sealing effect and efficient recovery of the O-ring in high temperature operation, providing a more reliable and durable solution for industrial applications. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Example 1

[0039] This embodiment provides a method for preparing EPDM rubber for low-pressure color-changing environmentally friendly O-rings, comprising the following steps:

[0040] Step 1: Weigh the raw materials;

[0041] Reinforcing agent 40kg;

[0042] Plasticizer 10kg;

[0043] Active agent 4.2kg;

[0044] Active agent modifier: gC 3 N 4 / Shell powder composite particles 2.3kg;

[0045] Modified vulcanizing agent 5.3kg;

[0046] Colorant 5.8kg;

[0047] EPDM rubber 58kg;

[0048] In the modified vulcanizing agent, the mass ratio of the vulcanizing agent, hydroxypropyl methylcellulose acetate succinate, potassium silicate and chitosan is 36:6:8:18;

[0049] The reinforcing agent is a mixture of precipitated silica VN3 and dry-calcined kaolin in a mass ratio of 4:5;

[0050] The dry calcined kaolin was purchased from Lingshou County Longde Mineral Products Sales Co., Ltd.

[0051] The plasticizer was purchased from Hebei Ideal Composite Materials Co., Ltd. PB2251 plasticizer;

[0052] The vulcanizing agent is Kemao XLA-60GA;

[0053] The active agent is liquid polyethylene glycol with a molecular weight of 300;

[0054] The colorant is purchased from Shandong Yuquan New Material Technology Co., Ltd. paint and rubber colorant;

[0055] The model of the EPDM rubber is KUMHO KEP330;

[0056] Step 2: preparing a modified vulcanizing agent;

[0057] A. Put the vulcanizing agent into 120 kg of water at 60° C. to prepare a suspension; heat the suspension to 80° C. at a rate of 15° C. / min, and add molten hydroxypropyl methylcellulose acetate succinate to the suspension to obtain a mixture A;

[0058] B. Adjust the pH of 42% potassium silicate solution to 10, add chitosan and react for 30 minutes, then adjust the pH to 4 to degrade chitosan and precipitate modified silicon dioxide in the solution; centrifuge to obtain solid, and dry to obtain solid B;

[0059] C. Add solid B into mixture A, disperse evenly and keep warm at 75°C for 15 minutes to obtain a modified vulcanizing agent;

[0060] Step 3: preparing a modified active agent;

[0061] Preheat the active agent to 53°C and add 1 / 3 of gC 3 N 4 / shell powder composite particles, stirred at 300r / min for 20min, while heating at 5℃ / min by 15℃; added 1 / 3 gC 3 N 4 / shell powder composite particles, stirred at 300r / min for 20min, kept warm for 8min; added the remaining gC 3 N 4 / shell powder composite particles, stirring at a speed of 300r / min for 20min, and heating to 82°C at a speed of 5°C / min while stirring to obtain a modified active agent;

[0062] Step 4: calcine 40% of the total amount of the reinforcing agent at 900°C for 3 hours and grind into powder; mix the remaining reinforcing agent and plasticizer evenly to obtain a mixture C;

[0063] Step 5: Put the EPDM rubber and the calcined reinforcing agent into the internal mixer, mix at 142°C for 80 seconds, then lift the hammer and clean it; put the colorant, mixture C, modified activator and modified vulcanizer into the internal mixer, mix at 162°C for 100 seconds, then unload the material and produce sheets to obtain low-pressure color-changing environmentally friendly O-ring EPDM rubber.

[0064] The gC 3 N 4 / Shell powder composite particles are selected from Zhang Xiaolan. Preparation and antibacterial properties of g-C_3N_4 / shell powder / PE composite film[D]. Xi'an University of Technology, 2024.DOI:10.27398 / d.cnki.gxalu.2024.000599.

[0065] The hydroxypropyl methylcellulose acetate succinate was purchased from Hebei Chuangzhiyuan Biotechnology Co., Ltd.

[0066] Example 2

[0067] This embodiment provides a method for preparing EPDM rubber for low-pressure color-changing environmentally friendly O-rings, comprising the following steps:

[0068] Step 1: Weigh the raw materials;

[0069] Reinforcing agent 35kg;

[0070] Plasticizer 8kg;

[0071] Active agent 3.6kg;

[0072] Active agent modifier: gC 3 N 4 / Shell powder composite particles 1.9kg;

[0073] Modified vulcanizing agent 3.8kg;

[0074] Colorant 2.7kg;

[0075] EPDM 45kg;

[0076] In the modified vulcanizing agent, the mass ratio of the vulcanizing agent, hydroxypropyl methylcellulose acetate succinate, potassium silicate and chitosan is 25:3:5:15;

[0077] The reinforcing agent is a mixture of precipitated silica VN3 and dry calcined kaolin in a mass ratio of 3:2;

[0078] The dry calcined kaolin was purchased from Lingshou County Longde Mineral Products Sales Co., Ltd.

[0079] The plasticizer was purchased from Hebei Ideal Composite Materials Co., Ltd. PB2251 plasticizer;

[0080] The vulcanizing agent is Kemao XLA-60GA;

[0081] The active agent is liquid polyethylene glycol with a molecular weight of 400;

[0082] The colorant is purchased from Shandong Yuquan New Material Technology Co., Ltd. paint and rubber colorant;

[0083] The model of the EPDM rubber is KUMHO KEP330;

[0084] Step 2: preparing a modified vulcanizing agent;

[0085] A. Put the vulcanizing agent into 100 kg of water at 45°C to prepare a suspension; heat the suspension to 75°C at a rate of 10°C / min, and add molten hydroxypropyl methylcellulose acetate succinate to the suspension to obtain a mixture A;

[0086] B. Adjust the pH of 38% potassium silicate solution to 9, add chitosan and react for 20 minutes, then adjust the pH to 3 to degrade chitosan and precipitate modified silicon dioxide in the solution; centrifuge to obtain solid, and dry to obtain solid B;

[0087] C. Add solid B into mixture A, disperse evenly and keep warm at 70°C for 10 minutes to obtain a modified vulcanizing agent;

[0088] Step 3: preparing a modified active agent;

[0089] Preheat the active agent to 42°C and add 1 / 4 gC 3 N 4 / shell powder composite particles, stirred at 200r / min for 15min, while heating at 3℃ / min by 3℃; added 1 / 4 gC 3 N 4 / shell powder composite particles, stirred at 200r / min for 15min, kept warm for 5min; added the remaining gC 3 N 4 / shell powder composite particles, stirring at a speed of 200r / min for 15min, and heating to 80°C at a speed of 3°C / min while stirring to obtain a modified active agent;

[0090] Step 4: 30% of the total amount of the reinforcing agent is calcined at 800°C for 2 hours and then ground into powder; the remaining reinforcing agent is mixed evenly with the plasticizer to obtain a mixture C;

[0091] Step 5: Put the EPDM rubber and the calcined reinforcing agent into an internal mixer, mix them at 130°C for 50s, then lift the hammer and clean it; put the colorant, mixture C, modified activator and modified vulcanizer into the internal mixer, mix them at 145°C for 70s, then discharge the material and produce sheets to obtain low-pressure color-changing environmentally friendly O-ring EPDM rubber.

[0092] Example 3

[0093] This embodiment provides a method for preparing EPDM rubber for low-pressure color-changing environmentally friendly O-rings, comprising the following steps:

[0094] Step 1: Weigh the raw materials;

[0095] Reinforcing agent 38kg;

[0096] Plasticizer 9kg;

[0097] Active agent 3.9kg;

[0098] Active agent modifier: gC 3 N 4 / Shell powder composite particles 2.1kg;

[0099] Modified vulcanizing agent 4.2kg;

[0100] Colorant 3.8kg;

[0101] EPDM rubber 52kg;

[0102] In the modified vulcanizing agent, the mass ratio of the vulcanizing agent, hydroxypropyl methylcellulose acetate succinate, potassium silicate and chitosan is 29:5:6:17;

[0103] The reinforcing agent is a mixture of precipitated silica VN3 and dry calcined kaolin in a mass ratio of 3:4;

[0104] The dry calcined kaolin was purchased from Lingshou County Longde Mineral Products Sales Co., Ltd.

[0105] The plasticizer was purchased from Hebei Ideal Composite Materials Co., Ltd. PB2251 plasticizer;

[0106] The vulcanizing agent is Kemao XLA-60GA;

[0107] The active agent is liquid polyethylene glycol with a molecular weight of 300;

[0108] The colorant is purchased from Shandong Yuquan New Material Technology Co., Ltd. paint and rubber colorant;

[0109] The model of the EPDM rubber is KUMHO KEP330;

[0110] Step 2: preparing a modified vulcanizing agent;

[0111] A. Put the vulcanizing agent into 110 kg of water at 48°C to prepare a suspension; heat the suspension to 78°C at a rate of 14°C / min, and add molten hydroxypropyl methylcellulose acetate succinate to the suspension to obtain a mixture A;

[0112] B. The pH of a 40% potassium silicate solution was adjusted to 9, chitosan was added and reacted for 22 minutes, and then the pH was adjusted to 3 to degrade the chitosan and precipitate modified silicon dioxide in the solution; solids were collected by centrifugation and dried to obtain solid B;

[0113] C. Add solid B into mixture A, disperse evenly and keep warm at 74°C for 12 minutes to obtain a modified vulcanizing agent;

[0114] Step 3: preparing a modified active agent;

[0115] Preheat the active agent to 44°C and add 1 / 4 gC 3 N 4 / shell powder composite particles, stirred at 250r / min for 18min, while heating at 4℃ / min by 12℃; added 1 / 3 gC 3 N 4 / shell powder composite particles, stirred at 280r / min for 18min, kept warm for 7min; added the remaining gC 3 N 4 / shell powder composite particles, stirring at a speed of 290r / min for 16min, and heating to 82°C at a speed of 4°C / min while stirring to obtain a modified active agent;

[0116] Step 4: 35% of the total amount of the reinforcing agent is calcined at 820°C for 2 hours and then ground into powder; the remaining reinforcing agent is mixed evenly with the plasticizer to obtain a mixture C;

[0117] Step 5: Put the EPDM rubber and the calcined reinforcing agent into an internal mixer, mix them at 140°C for 60 seconds, then lift the hammer and clean it; put the colorant, mixture C, modified activator and modified vulcanizer into the internal mixer, mix them at 151°C for 80 seconds, then unload the material and produce sheets to obtain low-pressure color-changing environmentally friendly O-ring EPDM rubber.

[0118] Example 4

[0119] This embodiment provides a method for preparing EPDM rubber for low-pressure color-changing environmentally friendly O-rings, comprising the following steps:

[0120] Step 1: Weigh the raw materials;

[0121] Reinforcing agent 36kg;

[0122] Plasticizer 9kg;

[0123] Active agent 3.9kg;

[0124] Active agent modifier: gC 3 N 4 / Shell powder composite particles 2.1kg;

[0125] Modified vulcanizing agent 4.2kg;

[0126] Colorant 4.6kg;

[0127] EPDM rubber 52kg;

[0128] In the modified vulcanizing agent, the mass ratio of the vulcanizing agent, hydroxypropyl methylcellulose acetate succinate, potassium silicate and chitosan is 31:5:6:17;

[0129] The reinforcing agent is a mixture of precipitated silica VN3 and dry-calcined kaolin in a mass ratio of 3:5;

[0130] The dry calcined kaolin was purchased from Lingshou County Longde Mineral Products Sales Co., Ltd.

[0131] The plasticizer was purchased from Hebei Ideal Composite Materials Co., Ltd. PB2251 plasticizer;

[0132] The vulcanizing agent is Kemao XLA-60GA;

[0133] The active agent is liquid polyethylene glycol with a molecular weight of 300;

[0134] The colorant is purchased from Shandong Yuquan New Material Technology Co., Ltd. paint and rubber colorant;

[0135] The model of the EPDM rubber is KUMHO KEP330;

[0136] Step 2: preparing a modified vulcanizing agent;

[0137] A. Put the vulcanizing agent into 115 kg of water at 49°C to prepare a suspension; heat the suspension to 79°C at a rate of 14°C / min, and add molten hydroxypropyl methylcellulose acetate succinate to the suspension to obtain a mixture A;

[0138] B. The pH of a 41% potassium silicate solution was adjusted to 9, chitosan was added and reacted for 22 minutes, and then the pH was adjusted to 3 to degrade the chitosan and precipitate modified silicon dioxide in the solution; solids were collected by centrifugation and dried to obtain solid B;

[0139] C. Add solid B into mixture A, disperse evenly and keep warm at 74°C for 11 minutes to obtain a modified vulcanizing agent;

[0140] Step 3: preparing a modified active agent;

[0141] Preheat the active agent to 51°C and add 1 / 4 gC 3 N 4 / shell powder composite particles, stirred at 220r / min for 16min, while heating at 5℃ / min by 15℃; added 1 / 3 gC 3 N 4 / shell powder composite particles, stirred at 280r / min for 16min, kept warm for 7min; added the remaining gC 3 N 4 / shell powder composite particles, stirring at a speed of 230r / min for 18min, and heating to 82°C at a speed of 5°C / min while stirring to obtain a modified active agent;

[0142] Step 4: calcine 30% of the total amount of the reinforcing agent at 820°C for 2 hours and grind into powder; mix the remaining reinforcing agent and plasticizer evenly to obtain a mixture C;

[0143] Step 5: Put the EPDM rubber and the calcined reinforcing agent into the internal mixer, mix them at 137°C for 60 seconds, then lift the hammer and clean it; put the colorant, mixture C, modified activator and modified vulcanizer into the internal mixer, mix them at 151°C for 80 seconds, then unload the material and produce sheets to obtain the EPDM rubber for low-pressure color-changing environmentally friendly O-rings.

[0144] Comparative Example 1

[0145] The difference from Example 4 is that this comparative example does not add gC 3 N 4 / shell powder composite particles;

[0146] This embodiment provides a method for preparing EPDM rubber for low-pressure color-changing environmentally friendly O-rings, comprising the following steps:

[0147] Step 1: Weigh the raw materials;

[0148] Reinforcing agent 36kg;

[0149] Plasticizer 9kg;

[0150] Active agent 3.9kg;

[0151] Modified vulcanizing agent 4.2kg;

[0152] Colorant 4.6kg;

[0153] EPDM rubber 52kg;

[0154] In the modified vulcanizing agent, the mass ratio of the vulcanizing agent, hydroxypropyl methylcellulose acetate succinate, potassium silicate and chitosan is 31:5:6:17;

[0155] The reinforcing agent is a mixture of precipitated silica VN3 and dry-calcined kaolin in a mass ratio of 3:5;

[0156] The dry calcined kaolin was purchased from Lingshou County Longde Mineral Products Sales Co., Ltd.

[0157] The plasticizer was purchased from Hebei Ideal Composite Materials Co., Ltd. PB2251 plasticizer;

[0158] The vulcanizing agent is Kemao XLA-60GA;

[0159] The active agent is liquid polyethylene glycol with a molecular weight of 300;

[0160] The colorant is purchased from Shandong Yuquan New Material Technology Co., Ltd. paint and rubber colorant;

[0161] The model of the EPDM rubber is KUMHO KEP330;

[0162] Step 2: preparing a modified vulcanizing agent;

[0163] A. Put the vulcanizing agent into 115 kg of water at 49°C to prepare a suspension; heat the suspension to 79°C at a rate of 14°C / min, and add molten hydroxypropyl methylcellulose acetate succinate to the suspension to obtain a mixture A;

[0164] B. The pH of a 41% potassium silicate solution was adjusted to 9, chitosan was added and reacted for 22 minutes, and then the pH was adjusted to 3 to degrade the chitosan and precipitate modified silicon dioxide in the solution; solids were collected by centrifugation and dried to obtain solid B;

[0165] C. Add solid B into mixture A, disperse evenly and keep warm at 74°C for 11 minutes to obtain a modified vulcanizing agent;

[0166] Step 3: preparing a modified active agent;

[0167] The active agent was preheated to 51°C, stirred at a speed of 220 r / min for 16 minutes, and heated at a speed of 5°C / min while stirring by 15°C; stirred at a speed of 280 r / min for 16 minutes, and kept warm for 7 minutes; stirred at a speed of 230 r / min for 18 minutes, and heated to 82°C at a speed of 5°C / min while stirring to obtain a modified active agent;

[0168] Step 4: calcine 30% of the total amount of the reinforcing agent at 820°C for 2h and grind into powder; mix the remaining reinforcing agent and plasticizer evenly to obtain a mixture C;

[0169] Step 5: Put the EPDM rubber and the calcined reinforcing agent into the internal mixer, mix them at 137°C for 60 seconds, then lift the hammer and clean it; put the colorant, mixture C, modified activator and modified vulcanizer into the internal mixer, mix them at 151°C for 80 seconds, then unload the material and produce sheets to obtain the EPDM rubber for low-pressure color-changing environmentally friendly O-rings.

[0170] Comparative Example 2

[0171] The difference from Example 4 is that no hydroxypropyl methylcellulose acetate succinate was added in this comparative example;

[0172] This embodiment provides a method for preparing EPDM rubber for low-pressure color-changing environmentally friendly O-rings, comprising the following steps:

[0173] Step 1: Weigh the raw materials;

[0174] Reinforcing agent 36kg;

[0175] Plasticizer 9kg;

[0176] Active agent 3.9kg;

[0177] Active agent modifier: gC 3 N 4 / Shell powder composite particles 2.1kg;

[0178] Modified vulcanizing agent 4.2kg;

[0179] Colorant 4.6kg;

[0180] EPDM rubber 52kg;

[0181] In the modified vulcanizing agent, the mass ratio of vulcanizing agent, potassium silicate and chitosan is 31:5:17;

[0182] The reinforcing agent is a mixture of precipitated silica VN3 and dry-calcined kaolin in a mass ratio of 3:5;

[0183] The dry calcined kaolin was purchased from Lingshou County Longde Mineral Products Sales Co., Ltd.

[0184] The plasticizer was purchased from Hebei Ideal Composite Materials Co., Ltd. PB2251 plasticizer;

[0185] The vulcanizing agent is Kemao XLA-60GA;

[0186] The active agent is liquid polyethylene glycol with a molecular weight of 300;

[0187] The colorant is purchased from Shandong Yuquan New Material Technology Co., Ltd. paint and rubber colorant;

[0188] The model of the EPDM rubber is KUMHO KEP330;

[0189] Step 2: preparing a modified vulcanizing agent;

[0190] A. Add the vulcanizing agent into 115 kg of water at 49°C to prepare a suspension; heat the suspension to 79°C at a rate of 14°C / min to obtain a mixture A;

[0191] B. The pH of a 41% potassium silicate solution was adjusted to 9, chitosan was added and reacted for 22 minutes, and then the pH was adjusted to 3 to degrade the chitosan and precipitate modified silicon dioxide in the solution; solids were collected by centrifugation and dried to obtain solid B;

[0192] C. Add solid B into mixture A, disperse evenly and keep warm at 74°C for 11 minutes to obtain a modified vulcanizing agent;

[0193] Step 3: preparing a modified active agent;

[0194] Preheat the active agent to 51°C and add 1 / 4 gC 3 N 4 / shell powder composite particles, stirred at 220r / min for 16min, while heating at 5℃ / min by 15℃; added 1 / 3 gC 3 N 4 / shell powder composite particles, stirred at 280r / min for 16min, kept warm for 7min; added the remaining gC 3 N 4 / shell powder composite particles, stirring at a speed of 230r / min for 18min, and heating to 82°C at a speed of 5°C / min while stirring to obtain a modified active agent;

[0195] Step 4: calcine 30% of the total amount of the reinforcing agent at 820°C for 2h and grind into powder; mix the remaining reinforcing agent and plasticizer evenly to obtain a mixture C;

[0196] Step 5: Put the EPDM rubber and the calcined reinforcing agent into the internal mixer, mix them at 137°C for 60 seconds, then lift the hammer and clean it; put the colorant, mixture C, modified activator and modified vulcanizer into the internal mixer, mix them at 151°C for 80 seconds, then unload the material and produce sheets to obtain the EPDM rubber for low-pressure color-changing environmentally friendly O-rings.

[0197] Experimental example

[0198] The performance of Examples 1-4 and Comparative Examples 1-2 was tested, and the results were as follows:

[0199]

[0200] The EPDM rubber for low-pressure color-changing environmentally friendly O-ring prepared by the present invention has a hardness between 65-75, a tensile strength of ≥8Mpa, an elongation at break of ≥200%, and various mechanical properties meet the industry standards; the low-temperature resistance is effectively improved by adding hydroxypropyl methylcellulose acetate succinate, and the low-temperature resistance is effectively improved by adding gC 3 N 4 / shell powder composite particles significantly reduce the compression deformation rate at high temperature and improve the recovery.

[0201] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-pressure color-changing environmentally friendly EPDM rubber for O-rings, characterized in that: Includes the following components: 35-40 parts of reinforcing agent; 8-10 parts of plasticizer; 3.6-4.2 parts of active agent; 1.9-2.3 parts of g-C3N4 / shell powder composite particles; 3.8-5.3 parts of modified vulcanizing agent; Colorant 2.7-5.8 parts; 45-58 parts of EPDM rubber; The modified vulcanizing agent contains a vulcanizing agent, hydroxypropyl methylcellulose acetate succinate, potassium silicate and chitosan in a mass ratio of 25-36:3-6:5-8:15-18.

2. A method for preparing the EPDM rubber for low-pressure color-changing environmentally friendly O-ring as claimed in claim 1, characterized in that: The following steps are involved: Step 1: preparing a modified vulcanizing agent; A. Put a vulcanizing agent into water to prepare a suspension; heat the suspension to 75-80° C., and add molten hydroxypropyl methylcellulose acetate succinate to the suspension to obtain a mixture A; B. Adjust the pH of the potassium silicate solution to 9-10, add chitosan to react, and then adjust the pH to 3-4 to degrade the chitosan and precipitate modified silicon dioxide in the solution; centrifuge to obtain the solid, and dry to obtain solid B; C. Add solid B into mixture A, disperse evenly and keep warm at 70-75°C for 10-15 minutes to obtain a modified vulcanizing agent; Step 2: preparing a modified active agent; Preheat the active agent to 42-53°C, add 1 / 4-1 / 3 of the g-C3N4 / shell powder composite particles, stir, and raise the temperature by 3-15°C while stirring; add 1 / 4-1 / 3 of the g-C3N4 / shell powder composite particles, stir; add the remaining g-C3N4 / shell powder composite particles, stir, and raise the temperature to 80-82°C while stirring to obtain the modified active agent; Step 3: Take 30-40% of the total amount of the reinforcing agent, calcine it and grind it into powder; mix the remaining reinforcing agent and plasticizer evenly to obtain a mixture C; Step 4: Put the EPDM rubber and the calcined reinforcing agent into an internal mixer, mix them at 130-142°C, lift the hammer and clean them; put the colorant, mixture C, modified activator and modified vulcanizer into the internal mixer, mix them at 145-162°C, unload the materials and flake them to obtain the EPDM rubber for low-pressure color-changing environmentally friendly O-rings.

3. The preparation method according to claim 2, characterized in that: Step A specifically comprises: adding a vulcanizing agent into water at 45-60° C. to prepare a suspension; heating the suspension to 75-80° C. at a rate of 10-15° C. / min, and adding molten hydroxypropyl methylcellulose acetate succinate to the suspension to obtain a mixture A.

4. The preparation method according to claim 3, characterized in that: Step B specifically comprises: adjusting the pH of 38-42% potassium silicate solution to 9-10, adding chitosan to react for 20-30 minutes, adjusting the pH to 3-4 to degrade chitosan and precipitate modified silicon dioxide in the solution; centrifuging to obtain solids, and drying to obtain solid B.

5. The preparation method according to claim 4, characterized in that: In step B, the mass ratio of hydroxypropyl methylcellulose acetate succinate, potassium silicate and chitosan is 3-6:5-8:15-18.

6. The preparation method according to claim 5, characterized in that: Step two is specifically as follows: preheat the active agent to 42-53°C, add 1 / 4-1 / 3 of the g-C3N4 / shell powder composite particles, stir at a speed of 200-300r / min for 15-20min, and heat up at a rate of 3-5°C / min while stirring for 3-15°C; add 1 / 4-1 / 3 of the g-C3N4 / shell powder composite particles, stir at a speed of 200-300r / min for 15-20min, and keep warm for 5-8min; add the remaining g-C3N4 / shell powder composite particles, stir at a speed of 200-300r / min for 15-20min, and heat up to 80-82°C at a rate of 3-5°C / min while stirring to obtain the modified active agent.

7. The preparation method according to claim 6, characterized in that: Step three is as follows: 30-40% of the total amount of the reinforcing agent is calcined at 800-900° C. for 2-3 hours and then ground into powder; the remaining reinforcing agent is evenly mixed with the plasticizer to obtain a mixture C.

8. The preparation method according to claim 7, characterized in that: Step 4 is as follows: put the EPDM rubber and the calcined reinforcing agent into an internal mixer, mix them at 130-142°C, lift the hammer and clean them; put the colorant, mixture C, modified activator and modified vulcanizer into the internal mixer, mix them at 145-162°C, unload the materials and flake them to obtain the EPDM rubber for low-pressure color-changing environmentally friendly O-rings.

9. The preparation method according to claim 8, characterized in that: The reinforcing agent is a mixture of precipitated silica VN3 and dry calcined kaolin in a mass ratio of 3-4:2-5.

10. The preparation method according to claim 9, characterized in that: The active agent is liquid polyethylene glycol with a molecular weight of 300-400.

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