Production process for manufacturing sealing strip from regenerated rubber

Abstract

The invention discloses a production process for manufacturing a sealing strip from regenerated rubber, belongs to the technical field of rubber product manufacturing, and discloses a production process for manufacturing a sealing strip from regenerated rubber. Comprising the following steps: performing microwave and biological desulfurization synergistic composite desulfurization treatment on the waste rubber, performing a segmented mixing process combining an internal mixer and an open mill, performing a microwave and hot air combined composite vulcanization process, and performing post-treatment. Through the application of a reinforcing agent compounded by modified carbon black and nano silicon dioxide and a poly (propylene glycol adipate) environment-friendly softening agent, and by combining an efficient sectional mixing and composite vulcanization technology, the mechanical properties, including tensile strength and wear resistance, of the sealing strip are remarkably improved, meanwhile, emission of volatile organic compounds in the mixing process is reduced, the vulcanization uniformity of the inner layer and the outer layer is improved, and the service life of the sealing strip is prolonged. And the compression set is controlled below 30%. The method takes high-value utilization of waste rubber as a core, has environmental protection property and high performance, and is suitable for production of sealing strips in the fields of automobiles, buildings and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of rubber product manufacturing, and particularly relates to a production process for manufacturing sealing strips from recycled rubber. Background Art

[0002] As the core carrier for goods transportation and warehousing, the performance of the sealing strips of logistics boxes directly affects the moisture-proof, dust-proof, anti-corrosion and safety of goods. Especially in scenarios such as cold chain logistics and fresh food transportation, the sealing strips need to withstand severe conditions such as long-term high and low temperature cycles, humidity changes, and mechanical vibrations. The production of traditional logistics box sealing strips relies on natural rubber or synthetic rubber as raw materials. The consumption of new rubber raw materials requires a large amount of petroleum resources or natural rubber tree planting resources, with high costs and unsustainability. Among the tens of millions of tons of waste rubber generated globally each year, only less than 40% is effectively recycled. The traditional high-temperature desulfurization process has high energy consumption and releases a large amount of pollutants such as hydrogen sulfide and benzene series. The traditional single hot air vulcanization process has problems of uneven vulcanization of the inner and outer layers, resulting in a significant decrease in the low-temperature elasticity of the sealing strips, easy occurrence of cracks or hardening, and causing sealing failure. The tensile strength of the sealing strips reinforced with ordinary carbon black is only 6 - 7 MPa, and the wear resistance is insufficient, making them easy to break in the scenarios of frequent opening and closing and friction of logistics boxes, with a short service life, usually less than 1 year. There are also pollution and health risks. The traditional process uses aromatic oil as a softening agent, and volatile organic compounds such as benzene and toluene are released during the mixing process, which not only pollutes the environment but also poses a threat to the health of production workers.

[0003] Therefore, developing a production process for logistics box sealing strips with recycled rubber as the core raw material, having high strength, weather resistance, and low pollution, is of great significance for promoting the development of the green packaging industry. Summary of the Invention

[0004] In view of the above pain points, the present invention provides a production process for manufacturing sealing strips from recycled rubber. It is a production method for preparing high-performance sealing strips by using waste rubber as the raw material and through processes such as microwave-biological composite desulfurization, segmented mixing, microwave-hot air composite vulcanization, and surface treatment, solving the problems of high pollution and poor performance in traditional processes.

[0005] The solution of the present invention is as follows:

[0006] A production process for manufacturing sealing strips from recycled rubber, characterized by comprising the following steps:

[0007] S1. Pretreat the waste rubber, including crushing and composite desulfurization treatment, and the composite desulfurization treatment is a combination of microwave desulfurization and biological desulfurization;

[0008] S2. Mix and blend the raw materials according to the formula. The raw materials include recycled rubber, new rubber, reinforcing agent, softening agent, vulcanizing agent, activator, and anti-aging agent, wherein the reinforcing agent is a compound of modified carbon black and nano-silica;

[0009] S3. Adopt a segmented mixing process. In the first-stage mixing, add recycled rubber, new rubber, reinforcing agent and softening agent. In the second-stage mixing, add vulcanizing agent, activator and antioxidant.

[0010] S4. Conduct composite vulcanization treatment on the formed seal strip blank. The composite vulcanization treatment is a combination of microwave vulcanization and hot air vulcanization.

[0011] S5. Conduct post-treatment on the vulcanized seal strip, including cooling and shaping, trimming and surface treatment.

[0012] Preferably, the frequency of the microwave desulfurization is 2450 MHz, the power is 5 to 10 kW, and the treatment time is 30 to 60 minutes. The biological desulfurization uses a microbial flora containing sulfur-oxidizing bacteria and Desulfovibrio desulfuricans, and reacts for 24 to 48 hours under the conditions of 25 to 35 °C and pH 6.5 to 7.5.

[0013] Preferably, the new rubber is a mixture of natural rubber and styrene-butadiene rubber with a mass ratio of 1:1, accounting for 10% to 20% of the total mass of the raw materials. The softening agent is polypropylene glycol adipate with a molecular weight of 1000 to 3000, accounting for 5% to 15% of the total mass of the raw materials, replacing traditional aromatic oil to reduce the emission of volatile organic compounds (VOCs) during the mixing process.

[0014] Preferably, the modified carbon black is prepared by treatment with a silane coupling agent. The dosage of the silane coupling agent is 2% to 5% of the mass of the carbon black, and the treatment conditions are stirring and reacting in an ethanol solution at 60 to 80 °C for 2 to 4 hours. The modified carbon black in the reinforcing agent accounts for 15% to 25%, and the nano-silica accounts for 3% to 8%.

[0015] Preferably, in the segmented mixing process, the first-stage mixing is carried out in a internal mixer at a temperature of 80 to 100 °C, a rotation speed of 30 to 50 r / min, and a mixing time of 5 to 10 minutes. The second-stage mixing is carried out on a two-roll mill at a roll temperature of 50 to 70 °C, and the number of thin passes is 3 to 5 times. The dispersion degree of the mixed rubber is controlled by on-line monitoring to be not less than 90% to avoid premature decomposition of the vulcanizing agent.

[0016] Preferably, the composite vulcanization treatment includes: preheating with hot air at 80 to 100 °C for 10 to 15 minutes, microwave vulcanization with a power of 3 to 8 kW and a time of 5 to 10 minutes, and post-vulcanization with hot air at 120 to 140 °C for 20 to 30 minutes, so that the compression set of the seal strip does not exceed 30% after being maintained at 70 °C for 22 hours, and the uniformity of vulcanization of the inner and outer layers is improved by 80%.

[0017] Preferably, the surface treatment is to coat a polyurethane wear-resistant coating with a thickness of 0.05 to 0.1 mm.

[0018] Compared with the prior art, the advantages of the present invention are as follows:

[0019] (1) The composite desulfurization process synergistically enhances efficiency, taking into account both efficiency and environmental protection: By combining microwave desulfurization and biological desulfurization, the plasticity of recycled rubber is increased by more than 30%, the residual amount of sulfides is reduced by 60%, the energy consumption is reduced by 40% compared with traditional chemical desulfurization, and the wastewater discharge is reduced by 70%, solving the problems of pollution and unstable performance in the regeneration of waste rubber from the source;

[0020] (2) Environmentally friendly formulation and staged mixing achieve low emissions and high dispersion: Using poly(propylene glycol adipate) with a molecular weight of 1000 - 3000 as a softening agent, the VOCs emissions during the mixing process are reduced by more than 60%, meeting the requirements of the EU REACH regulation; The staged mixing process is combined with on-line dispersion monitoring to avoid premature decomposition of the vulcanizing agent, enabling the reinforcing agent to be evenly distributed in the rubber matrix, laying a foundation for the subsequent uniformity of vulcanization;

[0021] (3) High-performance reinforcement and surface treatment: After the modified carbon black is surface-treated with a silane coupling agent and compounded with nano-silica, the tensile strength of the sealing strip is ≥8 MPa and the wear resistance is improved by 40%; A polyurethane wear-resistant coating with a thickness of 0.05 - 0.1 mm is coated on the surface to further enhance the weather resistance and scratch resistance, meeting the requirements of harsh scenarios such as automotive doors and windows and high-speed rail sealing. Description of the Drawings

[0022] Figure 1 It is a schematic process flow diagram of a production process for manufacturing a sealing strip from recycled rubber. Detailed Embodiments

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] Example 1

[0025] Raw material composition, by mass:

[0026] Recycled rubber: 70 parts, obtained after pretreatment by S1;

[0027] New rubber: 15 parts, the mass ratio of natural rubber to styrene-butadiene rubber is 1:1;

[0028] Reinforcing agent: 12 parts, 20% modified carbon black, 5% nano-silica, and the rest is the carrier;

[0029] Softening agent: 10 parts, poly(propylene glycol adipate) with a molecular weight of 2000;

[0030] Vulcanizing agent: 2 parts, sulfur;

[0031] Activator: 3 parts, a compound of zinc oxide and stearic acid;

[0032] Antioxidant: 1 part, N-phenyl-2-naphthylamine.

[0033] Preparation steps:

[0034] S1. Pretreatment of waste rubber.

[0035] Crush the waste rubber to a particle size of ≤5 mm, put it into a microwave desulfurization device, and process it for 45 minutes under the conditions of a frequency of 2450 MHz and a power of 7.5 kW. Then transfer it to a biological desulfurization reactor, add a microbial flora containing sulfur-oxidizing bacteria and Desulfovibrio desulfuricans, with a bacterial liquid concentration of 1×10 8 CFU / mL, control the temperature at 30°C and pH 7.0, and react for 36 hours to obtain recycled rubber with a 40% increase in plasticity and a 65% reduction in sulfide residue.

[0036] S2. Raw material mixing.

[0037] Weigh the recycled rubber, new rubber, reinforcing agent (modified carbon black treated with a silane coupling agent: the dosage of the silane coupling agent is 3% of the mass of the carbon black, and stir and react in an ethanol solution at 70°C for 3 hours), softening agent, vulcanizing agent, activator, and antioxidant according to the formula, and set aside.

[0038] S3. Segmented mixing process.

[0039] First-stage mixing: Put the recycled rubber, new rubber, reinforcing agent, and softening agent into an internal mixer, control the temperature at 90°C and the rotation speed at 40 r / min, and mix for 8 minutes until the materials are initially uniform;

[0040] Second-stage mixing: Transfer the internally mixed materials to an open mill, with a roll temperature of 60°C, add the vulcanizing agent, activator, and antioxidant, and thin-pass 4 times. Control the dispersion degree of the mixed rubber to reach 92% through on-line monitoring to avoid premature decomposition of the vulcanizing agent.

[0041] S4. Composite vulcanization treatment.

[0042] Preheat the formed seal strip blank in hot air at 90°C for 12 minutes, transfer it to a microwave vulcanization device, vulcanize it at a power of 5 kW for 8 minutes, and then place it in hot air at 130°C for post-vulcanization for 25 minutes, so that the compression set (70°C×22 h) of the seal strip is 28%, and the vulcanization uniformity of the inner and outer layers is increased by 85%.

[0043] S5. Post-treatment.

[0044] After vulcanization, the seal strip is cooled and shaped by circulating cooling water. After removing the flash, a polyurethane wear-resistant coating with a thickness of 0.08 mm is coated on the surface and dried naturally for 2 hours to obtain the finished seal strip.

[0045] Example 2

[0046] Raw material composition, by mass:

[0047] Recycled rubber: 65 parts, obtained after pretreatment with S1;

[0048] New rubber: 18 parts, the mass ratio of natural rubber to styrene-butadiene rubber is 1:1;

[0049] Reinforcing agent: 13 parts, modified carbon black 22%, nano silicon dioxide 6%, and the rest is carrier;

[0050] Softener: 9 parts, polypropylene adipate with a molecular weight of 1500;

[0051] Curing agent: 2.5 parts, sulfur and dicumyl peroxide are mixed in a mass ratio of 1:1;

[0052] Active agent: 3.5 parts, zinc oxide and stearic acid are compounded in a mass ratio of 2:1;

[0053] Antioxidant: 1.2 parts, "N-phenyl-2-naphthylamine" and "4,4'-bis(α,α-dimethylbenzyl)diphenylamine" are compounded in a mass ratio of 1:1.

[0054] Preparation steps:

[0055] S1. Pretreatment of waste rubber.

[0056] The waste rubber was crushed to a particle size of ≤4 mm and placed in a microwave desulfurization device for 40 minutes at a frequency of 2450 MHz and a power of 8 kW. It was then transferred to a biological desulfurization reactor and a microbial flora of sulfur-oxidizing bacteria and Vibrio desulfuricans was added. The bacterial liquid concentration was 1.2×10 8 CFU / mL, controlled temperature at 32°C, pH 7.2, and reacted for 32 hours to obtain recycled rubber with a 38% increase in plasticity and a 63% decrease in sulfide residue.

[0057] S2. Mixing of raw materials.

[0058] According to the formula, the recycled rubber, new rubber, reinforcing agent (modified carbon black treated with silane coupling agent: the amount of silane coupling agent is 3.5% of the mass of carbon black, and stirred in 75°C ethanol solution for 3.5 hours), softener, vulcanizer, activator and antioxidant are accurately weighed to prepare for subsequent mixing.

[0059] S3, segmented mixing process.

[0060] The first stage of mixing: add recycled rubber, new rubber, reinforcing agent and softener into the internal mixer, control the temperature at 95℃ and the speed at 45r / min, and mix for 7 minutes to allow the materials to reach a preliminary uniform mixing state;

[0061] Second-stage mixing: Transfer the material after internal mixing to an open mill, with the roll temperature at 65°C. Add vulcanizing agent, activator, and antioxidant, and thin-pass 4 times. Use an on-line monitoring system to ensure that the dispersion degree of the mixed rubber reaches 93%, and prevent premature decomposition of the vulcanizing agent.

[0062] S4. Composite vulcanization treatment.

[0063] First, preheat the formed seal strip blank in hot air at 95°C for 13 minutes, then transfer it to a microwave vulcanization device and vulcanize it at a power of 6 kW for 7 minutes. Finally, post-vulcanize it in hot air at 135°C for 22 minutes, so that the compression set (70°C × 22 h) of the seal strip is 26%, and the uniformity of vulcanization of the inner and outer layers is improved by 87%.

[0064] S5. Post-treatment.

[0065] The vulcanized seal strip is cooled and shaped through a cooling water circulation, carefully removing the burrs, and then coating a polyurethane wear-resistant coating with a thickness of 0.09 mm on the surface and drying it naturally for 2.2 hours to make the finished seal strip.

[0066] Example 3

[0067] Raw material composition, by mass:

[0068] Recycled rubber: 75 parts, obtained after pretreatment in S1;

[0069] New rubber: 12 parts, with the mass ratio of natural rubber to styrene-butadiene rubber being 1:1;

[0070] Reinforcing agent: 10 parts, 18% modified carbon black, 4% nano-silica, and the rest is the carrier;

[0071] Softening agent: 11 parts, polypropylene glycol adipate with a molecular weight of 2500;

[0072] Vulcanizing agent: 1.8 parts, dicumyl peroxide;

[0073] Activator: 2.8 parts, compounded by zinc oxide and stearic acid with a mass ratio of 3:1;

[0074] Antioxidant: 0.8 part, "4,4'-bis(α,α-dimethylbenzyl) diphenylamine".

[0075] Preparation steps:

[0076] S1. Pretreatment of waste rubber.

[0077] The waste rubber is crushed to a particle size of ≤6 mm and fed into a microwave desulfurization device. It is processed for 50 minutes under the conditions of a frequency of 2450 MHz and a power of 7 kW, and then transferred to a biological desulfurization reactor. A microbial flora containing sulfur-oxidizing bacteria and Desulfovibrio desulfuricans is added, and the bacterial liquid concentration is 0.8×10 8 CFU / mL. The temperature is controlled at 28°C and the pH at 6.8, and the reaction is carried out for 40 hours to obtain recycled rubber with a 36% increase in plasticity and a 61% reduction in the residual amount of sulfide.

[0078] S2. Raw material mixing.

[0079] Weigh the recycled rubber, new rubber, reinforcing agent (modified carbon black treated with a silane coupling agent: the dosage of the silane coupling agent is 2.5% of the mass of the carbon black, and the stirring reaction is carried out in an ethanol solution at 65°C for 4 hours), softening agent, vulcanizing agent, activator, and antioxidant according to the formula.

[0080] S3. Staged mixing process.

[0081] The first-stage mixing: Add the recycled rubber, new rubber, reinforcing agent, and softening agent to an internal mixer, control the temperature at 85°C and the rotation speed at 35 r / min, and mix for 9 minutes to preliminarily mix the materials evenly.

[0082] The second-stage mixing: Transfer the internal mixer materials to an open mill, with a roll temperature of 55°C. Add the vulcanizing agent, activator, and antioxidant, and thin-pass 3 times. Ensure that the dispersion degree of the mixed rubber reaches 91% through on-line monitoring to avoid premature decomposition of the vulcanizing agent.

[0083] S4. Composite vulcanization treatment.

[0084] The formed seal strip blank is first preheated in hot air at 85°C for 14 minutes, then transferred to a microwave vulcanization device, vulcanized at a power of 4 kW for 9 minutes, and finally post-vulcanized in hot air at 125°C for 28 minutes, so that the compression set (70°C×22 h) of the seal strip is 29%, and the vulcanization uniformity of the inner and outer layers is improved by 83%.

[0085] S5. Post-treatment.

[0086] The vulcanized seal strip is cooled and shaped by circulating cooling water. After removing the burrs, a polyurethane wear-resistant coating with a thickness of 0.07 mm is coated on the surface and naturally dried for 1.8 hours to obtain the finished seal strip.

[0087] Example 4

[0088] Raw material composition, by mass:

[0089] Recycled rubber: 62 parts, obtained after pretreatment by S1;

[0090] New rubber: 22 parts, the mass ratio of natural rubber to styrene-butadiene rubber is 1:1;

[0091] Reinforcing agent: 16 parts, modified carbon black 24%, nano silicon dioxide 7%, and the rest is carrier;

[0092] Softener: 7 parts, polypropylene adipate with a molecular weight of 1200;

[0093] Curing agent: 3.2 parts, sulfur and dicumyl peroxide are mixed in a mass ratio of 3:1;

[0094] Active agent: 4.2 parts, zinc oxide and stearic acid are compounded in a mass ratio of 5:2;

[0095] Antiaging agent: 1.5 parts, "N-phenyl-2-naphthylamine" and "4,4'-bis(α,α-dimethylbenzyl)diphenylamine" are compounded in a mass ratio of 2:1.

[0096] Preparation steps:

[0097] S1. Pretreatment of waste rubber.

[0098] The waste rubber was crushed to a particle size of ≤3mm and placed in a microwave desulfurization device for 35 minutes at a frequency of 2450MHz and a power of 9kW. It was then transferred to a biological desulfurization reactor and a microbial flora of sulfur-oxidizing bacteria and desulfurizing Vibrio was added. The bacterial liquid concentration was 1.5×10 8 CFU / mL, controlled temperature at 34°C and pH 7.4, reacted for 28 hours, and obtained recycled rubber with 42% increased plasticity and 67% reduced sulfide residue.

[0099] S2. Mixing of raw materials.

[0100] According to the formula, the recycled rubber, new rubber, reinforcing agent (modified carbon black treated with silane coupling agent: the amount of silane coupling agent is 4% of the mass of carbon black, stirred and reacted in 85°C ethanol solution for 2.5 hours), softener, vulcanizer, activator and antioxidant were accurately weighed.

[0101] S3, segmented mixing process.

[0102] The first stage of mixing: put the recycled rubber, new rubber, reinforcing agent and softener into the internal mixer, control the temperature at 105℃ and the speed at 55r / min, mix for 6 minutes to quickly mix the materials;

[0103] The second stage of mixing: transfer the mixed materials to the open mixing mill, set the roller temperature at 75℃, add the vulcanizing agent, activating agent and antioxidant, and pass the mixture through 5 times. Through online monitoring, the dispersion of the mixed rubber reaches 94% to prevent the vulcanizing agent from decomposing prematurely.

[0104] S4, composite vulcanization treatment.

[0105] First, preheat the formed seal strip blank in hot air at 105°C for 11 minutes, then transfer it to a microwave vulcanization device and vulcanize it at a power of 7 kW for 6 minutes. Finally, post-vulcanize it in hot air at 145°C for 18 minutes, so that the compression set (70°C × 22 h) of the seal strip is 23%, and the vulcanization uniformity of the inner and outer layers is improved by 90%.

[0106] S5. Post-treatment.

[0107] After the vulcanized seal strip is cooled and shaped by circulating cooling water, and the burrs are removed, a polyurethane wear-resistant coating with a thickness of 0.11 mm is coated on the surface and dried naturally for 1.6 hours to make the finished seal strip.

[0108] Example 5

[0109] Raw material composition, by mass:

[0110] Recycled rubber: 72 parts, obtained after pretreatment by S1;

[0111] New rubber: 16 parts, the mass ratio of natural rubber to styrene-butadiene rubber is 1:1;

[0112] Reinforcing agent: 11 parts, 19% of modified carbon black, 4.5% of nano-silica, and the rest is the carrier;

[0113] Softening agent: 10 parts, polypropylene glycol adipate with a molecular weight of 2200;

[0114] Vulcanizing agent: 2.2 parts, sulfur;

[0115] Activator: 3.3 parts, zinc oxide and stearic acid are compounded according to a mass ratio of 2.5:1;

[0116] Antioxidant: 1.1 parts, N-phenyl-2-naphthylamine.

[0117] Preparation steps:

[0118] S1. Pretreatment of waste rubber.

[0119] Crush the waste rubber to a particle size ≤ 4.5 mm, put it into a microwave desulfurization device, and process it for 42 minutes under the conditions of a frequency of 2450 MHz and a power of 7.8 kW; then transfer it to a biological desulfurization reactor, add a microbial flora containing sulfur-oxidizing bacteria and Desulfovibrio desulfuricans, the bacterial liquid concentration is 1.1×10 8 CFU / mL, control the temperature at 31°C and pH at 7.1, and react for 34 hours to obtain recycled rubber with a 39% increase in plasticity and a 64% reduction in sulfide residue.

[0120] S2. Raw material mixing.

[0121] Accurately weigh the recycled rubber, new rubber, reinforcing agent (modified carbon black treated with silane coupling agent: the dosage of silane coupling agent is 3.2% of the mass of carbon black, and the stirring reaction is carried out in an ethanol solution at 72°C for 3.2 hours), softening agent, vulcanizing agent, activator and antioxidant according to the formula.

[0122] S3. Segmented mixing process.

[0123] First-stage mixing: Put the recycled rubber, new rubber, reinforcing agent and softening agent into the internal mixer, control the temperature at 92°C and the rotation speed at 42 r / min, and mix for 7.5 minutes to make the materials preliminarily and evenly mixed;

[0124] Second-stage mixing: Transfer the internally mixed materials to the open mill, with the roll temperature at 62°C, add the vulcanizing agent, activator and antioxidant, and thin-pass 4 times. Ensure that the dispersion degree of the mixed rubber reaches 92.5% through on-line monitoring to avoid premature decomposition of the vulcanizing agent.

[0125] S4. Composite vulcanization treatment.

[0126] The formed sealing strip blank is first preheated in hot air at 92°C for 12.5 minutes, then transferred to a microwave vulcanization device, vulcanized at a power of 5.5 kW for 7.5 minutes, and finally post-vulcanized in hot air at 132°C for 23.5 minutes, so that the compression set (70°C×22 h) of the sealing strip is 27%, and the uniformity of vulcanization of the inner and outer layers is increased by 86%.

[0127] S5. Post-treatment.

[0128] The vulcanized sealing strip is cooled and shaped by circulating cooling water. After removing the flash, a polyurethane wear-resistant coating with a thickness of 0.085 mm is coated on the surface and dried naturally for 1.9 hours to obtain the finished sealing strip.

[0129] Performance testing

[0130] Conduct a comprehensive performance test on the sealing strips prepared in the above Examples 1-5. The following are the detailed test results and the description of the test methods for each test item:

[0131] 1. Mechanical properties

[0132] 1-1. Tensile strength and elongation at break:

[0133] Test method: Test according to the GB / T528 standard; make the prepared sealing strip sample into a dumbbell-shaped specimen with specified dimensions, use a tensile testing machine to stretch the specimen at a constant tensile speed until the specimen breaks; during the stretching process, the testing machine records the maximum tensile force borne by the specimen and the elongation at break; calculate the ratio of the maximum tensile force to the original cross-sectional area of the specimen to obtain the tensile strength, and the ratio of the elongation at break to the original gauge length is the elongation at break;

[0134] Table 1

[0135]

[0136] Test results: The tensile strength of Example 4 reached 9.5 MPa, and the elongation at break was 380%, showing the best performance among several examples.

[0137] 1 - 2. Shore A hardness:

[0138] Test method: Execute in accordance with the GB / T531.1 standard; use a Shore A hardness tester to test the sealing strip sample; press the foot of the hardness tester steadily on the surface of the sample, and read the hardness value after the pointer stabilizes; during the test, multiple measurements need to be carried out at different parts of the sample, and the average value is taken as the final result;

[0139] Table 2

[0140]

[0141] Test results: The Shore A hardness of Example 4 was 69 degrees, which was relatively high; the Shore A hardness of Example 3 was 63 degrees, and the texture was relatively soft.

[0142] 2. Abrasion resistance

[0143] Test method: Conduct the abrasion resistance test according to the GB / T9867 standard; use an abrasion tester to rub the sealing strip sample with abrasives under certain pressure and friction conditions, and measure the abrasion volume of the sample after a specified friction stroke; the smaller the abrasion volume, the better the abrasion resistance of the sealing strip;

[0144] Table 3

[0145]

[0146] Test results: The abrasion amount of Example 4 was 11 mm 3 , with the best abrasion resistance.

[0147] 3. Compression set performance

[0148] Test method: Conduct the test according to the GB / T7759.1 standard. Place the sealing strip sample in a specific compression device, apply a specified compression force to the sample at 70 °C for 22 hours; then take out the sample, place it at room temperature for a certain time, and measure the thickness of the sample after recovery; by calculating the change rate of the thickness of the sample before and after compression, the compression set rate is obtained, and the smaller the compression set rate, the better;

[0149] Table 4

[0150]

[0151] Test results: The compression set (70°C × 22 h) of Example 4 is 23%, showing the best performance.

[0152] 4. Aging performance

[0153] 4-1. Retention rate of performance after hot air aging:

[0154] Test method: Conduct a hot air aging test according to the GB / T3512 standard; place the sealing strip sample in a hot air aging chamber and maintain it at a temperature of 70°C for 72 hours; after the aging test, test the tensile strength and elongation at break of the sample, and compare with the test results before aging to calculate the retention rates of tensile strength and elongation at break;

[0155] Table 5

[0156]

[0157]

[0158] Test results: After the hot air aging test, the retention rate of tensile strength of Example 4 is 90%, and the retention rate of elongation at break is 85%, showing outstanding performance.

[0159] 4-2. Ozone resistance aging performance

[0160] Test method: Conduct an ozone resistance aging test according to the GB / T7762 standard; stretch the sealing strip sample in an ozone concentration environment of 50 pphm at an elongation rate of 20% and maintain it for 48 hours; after the test, observe whether cracks appear on the surface of the sample to evaluate its ozone resistance aging performance;

[0161] Table 6

[0162]

[0163] Test results: In the ozone resistance aging test, no cracks appeared in Examples 1, 2, 4, and 5, showing good ozone resistance aging performance; while slight cracks appeared in Example 3.

[0164] 5. Oil resistance performance

[0165] Test method: Conduct an oil resistance performance test according to the GB / T1690 standard; immerse the sealing strip sample in IRM903 oil at 100°C for 24 hours, then take out the sample, dry the oil on the surface with filter paper, and measure the volume and mass changes of the sample before and after immersion; evaluate the oil resistance performance of the sealing strip by calculating the volume change rate and mass change rate. The smaller the volume change rate and mass change rate, the better the oil resistance performance;

[0166] Table 7

[0167]

[0168] Test results: The volume change rate of Example 4 is 8%, the mass change rate is 6%, and the oil resistance performance is the best.

[0169] 6. Emission of volatile organic compounds (VOCs)

[0170] Test method: The gas chromatography method is used to detect the VOCs emission during the mixing stage; during the mixing process, a certain amount of waste gas samples are collected, and the volatile organic compounds in the samples are separated and quantitatively analyzed by a gas chromatograph, the emission amount of VOCs is calculated, and it is compared with the control group that does not adopt the process of the present invention to obtain the reduction rate of the emission of volatile organic compounds (VOCs).

[0171] Table 8

[0172]

[0173] Test results: During the mixing stage, the VOCs emissions of each example are significantly reduced.

[0174] The above Examples 1-5 show that the present invention effectively improves the physical properties and environmental protection properties of the recycled rubber sealing strip through processes such as compound desulfurization, staged mixing, and compound vulcanization, meeting the requirements of industrial production.

[0175] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification are only preferred examples of the present invention and are not used to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A production process for manufacturing a sealing strip from recycled rubber, characterized in that, It includes the following steps: S1. Pretreat the waste rubber, including crushing and composite desulfurization treatment, and the composite desulfurization treatment is a combination of microwave desulfurization and biological desulfurization; S2. Mix the raw materials according to the formula. The raw materials include recycled rubber, new rubber, reinforcing agent, softening agent, vulcanizing agent, activator and antioxidant. The reinforcing agent is composed of a compound of modified carbon black and nano-silica; S3. Adopt a segmented mixing process. In the first-stage mixing, add recycled rubber, new rubber, reinforcing agent and softening agent. In the second-stage mixing, add vulcanizing agent, activator and antioxidant; S4. Conduct composite vulcanization treatment on the formed seal strip blank. The composite vulcanization treatment is a combination of microwave vulcanization and hot air vulcanization; S5. Conduct post-treatment on the vulcanized seal strip, including cooling and shaping, trimming and surface treatment.

2. The production process of manufacturing a sealing strip from recycled rubber according to claim 1, characterized in that, The frequency of the microwave desulfurization is 2450 MHz, the power is 5 to 10 kW, and the treatment time is 30 to 60 minutes; the biological desulfurization uses a microbial flora containing sulfur-oxidizing bacteria and Desulfovibrio, and reacts at 25 to 35 °C and pH 6.5 to 7.5 for 24 to 48 hours.

3. The production process of manufacturing a sealing strip from recycled rubber according to claim 1, characterized in that, The new rubber is a mixture of natural rubber and styrene-butadiene rubber, with a mass ratio of 1:1, accounting for 10% to 20% of the total mass of the raw materials; the softening agent is polypropylene glycol adipate with a molecular weight of 1000 to 3000, accounting for 5% to 15% of the total mass of the raw materials, replacing traditional aromatic oil and reducing the emission of volatile organic compounds (VOCs) during the mixing process.

4. The production process of manufacturing a sealing strip from recycled rubber according to claim 1, characterized in that, The modified carbon black is prepared by treatment with a silane coupling agent. The dosage of the silane coupling agent is 2% to 5% of the mass of the carbon black, and the treatment conditions are stirring reaction in an ethanol solution at 60 to 80 °C for 2 to 4 hours. In the reinforcing agent, the modified carbon black accounts for 15% to 25%, and the nano-silica accounts for 3% to 8%.

5. The production process of manufacturing a sealing strip from recycled rubber according to claim 1, characterized in that, In the segmented mixing process, the first-stage mixing is carried out in a mixer at a temperature of 80 to 100 °C, a rotation speed of 30 to 50 r / min, and a mixing time of 5 to 10 minutes; the second-stage mixing is carried out on an open mill at a roll temperature of 50 to 70 °C, with 3 to 5 passes of thin passing. The dispersion degree of the mixed rubber is controlled by on-line monitoring to be not less than 90% to avoid premature decomposition of the vulcanizing agent.

6. The production process of manufacturing a sealing strip from recycled rubber according to claim 1, characterized in that, The composite vulcanization treatment includes: preheating with hot air at 80 to 100 °C for 10 to 15 minutes, microwave vulcanization with a power of 3 to 8 kW and a time of 5 to 10 minutes, and post-vulcanization with hot air at 120 to 140 °C for 20 to 30 minutes, so that the compression set of the seal strip does not exceed 30% after being maintained at 70 °C for 22 hours, and the vulcanization uniformity of the inner and outer layers is improved by 80%.

7. The production process of manufacturing a sealing strip from recycled rubber according to claim 1, characterized in that, The surface treatment is to coat a polyurethane wear-resistant coating with a thickness of 0.05 to 0.1 mm.

Images