Process for producing near-zero voc super abrasion rubber articles with dual network crosslinking and articles

Abstract

The application discloses a production process of a double-network crosslinked near-zero VOC super-wear-resistant rubber product, belongs to the field of advanced processing technology of high polymer materials, and aims to solve the long-standing contradiction among reinforcement and elasticity, environmental protection and performance, and efficiency and quality in traditional rubber production processes. The process realizes the synchronous improvement of the super-wear resistance, high elasticity and long dynamic fatigue life of the rubber product through the cooperation of four core modules of in-situ interface polymerization modification of fillers, one-step closed mixing assisted by supercritical CO2, photo-thermal double-stage crosslinking vulcanization and whole-chain VOC closed-loop control, simultaneously achieves near-zero VOC emission, greatly improves the production efficiency and product batch stability, and is suitable for the large-scale preparation of rubber products in extreme working condition scenes such as new energy vehicles, aerospace and rail transit.

Description

Technical Field

[0001] This invention belongs to the field of advanced processing technology of polymer materials, specifically involving a rubber product manufacturing process and products that combine ultra-wear resistance, high elasticity, long dynamic fatigue life, and near-zero VOC emissions. It is particularly suitable for large-scale preparation in extreme working conditions such as chassis shock absorbers for new energy vehicles, aerospace sealing components, transmission components for high-end engineering machinery, and shock absorbers for rail transit. Background Technology

[0002] Rubber products are an indispensable core component in the field of high-end equipment manufacturing. With the rapid development of industries such as new energy vehicles, aerospace, and rail transportation, the performance of rubber products has been put forward with the extreme requirements of "four highs and two difficulties": high wear resistance, high elasticity, high fatigue resistance, and high environmental protection. At the same time, it is necessary to solve the problem of balancing low-temperature performance and wear resistance, and the problem of balancing production efficiency and batch stability.

[0003] Existing conventional and high-end rubber production processes have consistently failed to overcome three core technological contradictions that have long plagued the industry, representing "technical problems that the industry longs to solve but has consistently failed to resolve." First, there is the inherent contradiction between reinforcement and elasticity. Traditional processes improve wear resistance by increasing the amount of reinforcing fillers such as carbon black and silica. However, when the filler content exceeds 30 parts, agglomeration easily occurs, leading to a significant decrease in the elasticity of the rubber matrix, a surge in dynamic heat generation, and a sharp reduction in fatigue life. It is impossible to achieve a simultaneous improvement in "ultra-wear resistance and high elasticity". Existing coupling agent modification technology can only achieve physical compatibility between the filler and the matrix, but cannot form a continuous stress transmission network, thus failing to fundamentally solve this contradiction.

[0004] Second, there is a conflict between environmental protection and performance. Traditional VOC control relies solely on end-of-pipe adsorption, failing to reduce VOCs at the source. The numerous small-molecule additives (plasticizers, antioxidants, dispersants, etc.) added to enhance performance are a core source of VOCs, while replacing them with environmentally friendly additives often leads to performance degradation, making it impossible to achieve a balance between "near-zero VOC emissions and ultimate performance." Existing technologies cannot address the core challenge of additives being "non-migratory, non-volatile, and capable of cross-linking."

[0005] Third, there is the inherent contradiction between efficiency and quality. Traditional vulcanization processes employ a single constant-temperature hot vulcanization method, which results in an uncontrollable cross-linking reaction rate. This easily leads to localized under- or over-vulcanization, uneven distribution of the cross-linking network, high internal stress in the products, and poor batch stability. To ensure performance, the vulcanization time must be extended, resulting in low production efficiency and an inability to simultaneously improve "high-efficiency production and high performance and stability".

[0006] In addition, existing processes cannot meet the requirements of extreme working conditions: shock absorbers for new energy vehicles need to maintain a service life of more than 10 years under a wide temperature range of -40℃ to 120℃ and high-frequency dynamic working conditions. Traditional process products have a fatigue life of less than 3 years under these conditions, and their wear resistance and low-temperature elasticity retention cannot meet the standards.

[0007] In response to the aforementioned industry bottlenecks, this invention breaks through the technological path dependence of traditional processes and constructs a set of collaborative and innovative production processes throughout the entire process. This fundamentally solves the contradictions of the three core technologies and improves the performance of rubber products. Summary of the Invention

[0008] The core objective of this invention is to address the key deficiencies of existing technologies by providing a near-zero VOC ultra-wear-resistant rubber product manufacturing process with dual-network crosslinking, primarily solving the following technical problems: Breaking through the contradiction between reinforcement and elasticity in traditional processes, we achieve simultaneous improvement in the ultra-wear resistance, high elasticity, and long fatigue life of rubber products; We have built a closed-loop VOC control system covering the entire chain, achieving near-zero VOC emissions from source reduction, process capture to end-of-life degradation, far exceeding the most stringent environmental standards at home and abroad. Develop precise and controllable crosslinking processes to achieve uniform design of crosslinking networks, significantly improve batch stability, shorten production cycles, and reduce overall energy consumption and carbon emissions. Achieve stable performance across a wide temperature range to meet the extreme requirements of new energy vehicles, aerospace, and other extreme scenarios.

[0009] To achieve the above objectives, the specific technical solution of the present invention is as follows: This invention provides a manufacturing process for near-zero VOC ultra-wear-resistant rubber products with dual-network crosslinking, comprising the following steps: obtaining the basic formulation components to be processed, wherein the basic formulation, by weight, includes: 100 parts of matrix rubber, 30-50 parts of surface in-situ polymerized modified silica, a reactive functional additive system, a composite vulcanization system, 2-3 parts of active zinc oxide, and 1-1.5 parts of stearic acid; performing in-situ interfacial polymerization modification treatment on nano-silica to obtain modified silica with a flexible interfacial polymer layer on the surface that can participate in vulcanization crosslinking; preparing the final compound using a supercritical CO2-assisted closed-loop one-step mixing process; performing low-stress preforming on the final compound to obtain a preform with dimensional accuracy; performing vulcanization treatment on the preform using a photo-thermal dual-stage crosslinking vulcanization process to construct a dual-network crosslinking structure; and performing full-chain VOC closed-loop control post-treatment on the vulcanized product to obtain the finished rubber product.

[0010] Furthermore, the base rubber is a blend of 60-80 parts of high cis-butadiene rubber (BR) and 20-40 parts of solution-polymerized styrene-butadiene rubber (SSBR), with a Mooney viscosity ML(1+4)100℃ of 45-55; the high cis-BR ensures wear resistance and low-temperature performance, while the SSBR ensures slip resistance and processing performance, and there are no small molecule residual monomers.

[0011] Furthermore, the reactive functional additive system comprises, by weight, 6-12 parts of epoxy-based reactive polyester plasticizer, 1-2 parts of reactive hindered amine antioxidant, and 0.8-1.5 parts of reactive dispersant; the above components participate 100% in vulcanization crosslinking, with no migration or volatilization, thus eliminating VOC sources from the outset.

[0012] Furthermore, the composite vulcanization system comprises, by weight: 1.0 to 1.8 parts of insoluble sulfur IS-60, 0.3 to 0.6 parts of accelerator TBzTD, and 1.2 to 1.8 parts of accelerator CBS; the insoluble sulfur prevents blooming, the delayed-acting accelerator ensures vulcanization safety, and there is no precipitation of nitrosamines.

[0013] Further, the specific steps for in-situ interfacial polymerization modification of nano-silica are as follows: Nano-silica (specific surface area 160–200 m² / g) is added to a high-speed mixer, heated to 100–110°C, and vacuum dehydrated for 20 min to remove surface hydroxyl-bound water; the temperature is then lowered to 85–95°C, and a composite modification system is added. This composite modification system consists of silane coupling agent KH560 (epoxy-terminated) + hydroxyl-terminated butadiene-acrylonitrile rubber (HTBN, number average molecular weight 3000–5000) + initiator dicumyl peroxide (…). The DCP (dichlorosilane precipitate) is added at a mass ratio of 3:6:1, at a rate of 8%–12% of the mass of silica. Under high-speed shear conditions of 3500–4000 rpm, the in-situ polymerization reaction is carried out for 15–20 min, forming a flexible interfacial polymerization layer with a thickness of 5–10 nm on the surface of silica. One end of this interfacial layer is covalently bonded to the silica surface through silicon-oxygen bonds, while the other end has double bonds and epoxy groups that can participate in the vulcanization reaction. It can form an interpenetrating cross-linked network with the rubber matrix, completely solving the filler agglomeration problem and simultaneously constructing a continuous stress transmission network.

[0014] Furthermore, the specific steps of the supercritical CO2-assisted closed-loop one-step mixing process are as follows: The base rubber, in-situ modified silica, reactive functional additive system, active zinc oxide, and stearic acid are all added to a closed-loop mixer equipped with a supercritical CO2 injection system according to the formula; supercritical CO2 is injected into the mixer, controlling the system pressure at 8–12 MPa and the temperature at 55–65°C, and mixing at a speed of 35–45 rpm for 4–6 minutes; supercritical CO2 can rapidly penetrate into the spaces between rubber molecular chains, reducing melt viscosity by more than 60% and significantly improving... The filler dispersion efficiency can simultaneously extract residual small molecule monomers and oligomers in the rubber in advance; rapid pressure relief allows the extracted VOCs to be discharged simultaneously with CO2 and enter the VOC capture system; then, while maintaining the system temperature at 40-50℃, the composite vulcanization system is added and mixed at 25-35 rpm for 2-3 minutes, and the final rubber is obtained by discharge. The discharge temperature is strictly controlled at ≤100℃ to completely avoid the risk of scorching; the discharged CO2 is condensed and recovered with a recycling rate of ≥95%, and the extracted VOCs enter the subsequent degradation system simultaneously, with no fugitive emissions.

[0015] Furthermore, the specific steps of the low-stress preforming are as follows: the final compound is passed through a two-roll mill at room temperature 3-4 times, with the roll gap controlled at 0.3-0.8 mm, to eliminate internal stress in the compound; then, the preform is obtained by extrusion through a cold-feed precision extruder at an extrusion temperature of 45-55℃ and a screw speed of 15-25 rpm. A laser diameter gauge is used to control the dimensional tolerance of the preform in real time to ≤±0.05 mm, ensuring the dimensional accuracy of the product.

[0016] Further, the specific steps of the photo-thermal dual-stage crosslinking vulcanization process are as follows: First stage: room temperature ultraviolet pre-crosslinking. The preformed blank is placed in a vulcanization mold equipped with an ultraviolet irradiation module. Under normal pressure and room temperature conditions, an ultraviolet LED light source with a wavelength of 365nm is used for irradiation, with an irradiation intensity of 800-1200mW / cm² and an irradiation time of 30-60s. Through ultraviolet light excitation, the double bonds in the rubber compound undergo a pre-crosslinking reaction, constructing a uniformly distributed "physically entangled pre-crosslinking point network" throughout the entire rubber compound system. This provides uniform crosslinking nucleation sites for subsequent thermal vulcanization, completely avoiding local scorching and over-vulcanization problems. Second stage: three-stage gradient heating thermal vulcanization. After molding, the vulcanization pressure is kept constant at 12-15 MPa, and gradient temperature vulcanization is adopted: the first stage is heated to 138-142℃, and the vulcanization time is 35% of the total vulcanization time, so as to achieve uniform diffusion of vulcanizing agent and accelerator in pre-crosslinked network; the second stage is heated to 152-156℃, and the vulcanization time is 50% of the total vulcanization time, to complete the main vulcanization reaction, so that the interfacial polymer layer between the rubber matrix and the filler surface forms an interpenetrating chemical crosslinked double network; the third stage is cooled to 142-145℃, and the vulcanization time is 15% of the total vulcanization time, to complete the vulcanization reaction, eliminate internal stress of the product, and improve dimensional stability; the total vulcanization time is adjusted according to the thickness of the product, and the total vulcanization time of a 2mm thick product is only 6-7 minutes, which is more than 40% shorter than the traditional process.

[0017] Furthermore, the specific steps of the full-chain VOC closed-loop control post-treatment are as follows: the vulcanized product is immediately placed in a sealed oven equipped with an integrated vacuum devolatilization + photocatalytic degradation device, and firstly, it is devolatilized for 1 to 1.5 hours at a vacuum degree of -0.08 to -0.09 MPa and a temperature of 85 to 95°C to completely remove the residual trace small molecules in the product; the gas discharged from the devolatilization enters the photocatalytic degradation reactor, where ultraviolet light with a wavelength of 254 nm is used in conjunction with a nano-TiO2 catalyst to completely degrade the VOC into CO2 and H2O, with a degradation rate of ≥99.9% and no secondary pollution; subsequently, it is heat-treated at normal pressure and 80°C for 1 hour to eliminate the internal stress of the product, improve dimensional stability, and obtain the finished product.

[0018] The groundbreaking and beneficial effects of this invention are as follows: A complete breakthrough has been achieved in overcoming the inherent contradiction between reinforcement and elasticity, resulting in a significant improvement in overall performance. Through in-situ interfacial polymerization modification and photothermal dual-stage dual-network crosslinking, the dispersion of fillers in the rubber matrix is ​​increased by more than 60%, with no agglomeration. The tensile strength of the finished product is ≥22MPa, tear strength is ≥55kN / m, Akron abrasion loss is ≤0.05cm³ / 1.61km, and wear resistance is improved by more than 100% compared to traditional high-end processes. At the same time, the elongation at break is ≥550%, and the resilience is ≥65%, achieving a simultaneous improvement in ultra-wear resistance and high elasticity, resolving a decades-old inherent contradiction in the industry.

[0019] The product meets all performance standards under extreme working conditions, and its service life is significantly extended. The dual-network cross-linked structure gives the product excellent wide-temperature performance: elasticity retention rate ≥85% at -40℃, compression set ≤15% at 120℃; dynamic compression heat generation (Goodrich flexure test) ≤18℃, which is more than 60% lower than traditional processes; high-frequency dynamic fatigue life is increased by more than 300%, fully meeting the service life requirements of more than 10 years for new energy vehicles, and is suitable for extreme working conditions such as aerospace and rail transportation.

[0020] The entire process achieves near-zero VOC control, with environmental performance far exceeding international standards. Through source reduction using a reactive additive system, extraction via supercritical CO2 process, and end-stage photocatalytic degradation, fugitive VOC emissions during the sulfidation process are reduced by more than 95%, resulting in a finished product VOC content of ≤3μg / g. This is far below the most stringent limits stipulated by EU REACH regulations and GB / T39600-2021, achieving near-zero VOC emissions and eliminating any environmental risks.

[0021] Production efficiency and batch stability are significantly improved simultaneously. The mixing time is shortened by more than 50% compared with traditional processes, the vulcanization time is shortened by more than 40%, and the total production cycle is shortened by more than 50%. The supercritical CO2-assisted mixing and precise cross-linking process greatly reduces the impact of human and environmental factors, and the performance fluctuation between batches is ≤2.5%, which is far lower than the fluctuation level of more than 15% of traditional processes, realizing the large-scale stable production of high-end products.

[0022] Low-carbon and environmentally friendly, in line with the dual-carbon policy requirements. The comprehensive energy consumption per unit product is reduced by more than 35% compared with traditional processes, and CO2 emissions are reduced by more than 40%; the supercritical CO2 recycling rate is ≥95%, with no wastewater or waste residue generated. The entire process is green and low-carbon, in line with the national dual-carbon strategy requirements. Attached Figure Description

[0023] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 The following is a general flow chart of the manufacturing process of near-zero VOC ultra-wear-resistant rubber products with dual-network crosslinking provided in an embodiment of the present invention; Figure 2 A flowchart illustrating the steps of the photo-thermal two-stage crosslinking vulcanization process provided in an embodiment of the present invention is shown. Figure 3 A schematic diagram of the structure of the modified silica surface interface polymerization layer provided in an embodiment of the present invention is shown. Figure 4 A schematic diagram of the full-chain VOC closed-loop management system provided by an embodiment of the present invention is shown. Detailed Implementation

[0024] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the present application can be combined with each other.

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0026] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0027] The present invention will be further described in detail below with reference to specific embodiments and comparative examples. The embodiments are only used to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0028] Example 1 Formula (parts by weight): 70 parts high cis BR, 30 parts SSBR, 40 parts modified silica, 9 parts reactive polyester plasticizer, 1.5 parts reactive antioxidant, 1 part reactive dispersant, 1.5 parts insoluble sulfur IS-60, 0.4 parts accelerator TBzTD, 1.5 parts accelerator CBS, 2.5 parts active zinc oxide, and 1.2 parts stearic acid.

[0029] Process steps In-situ interfacial polymerization modification of filler: 40 parts of nano-silica and 4 parts of composite modification system (1.2 parts of KH560, 2.4 parts of HTBN, and 0.4 parts of DCP) were added to a high-speed mixer and vacuum dehydrated at 105℃ for 20 min. The temperature was then lowered to 90℃ and added to the composite modification system. The mixture was then subjected to in-situ polymerization reaction at 3800 rpm for 18 min to obtain modified silica with a flexible interfacial polymerization layer on the surface that can participate in sulfurization crosslinking. Supercritical CO2-assisted closed-loop one-step mixing: Take the base rubber, modified silica, reactive functional additive system, active zinc oxide, and stearic acid of the above formula by weight and put them into a closed-loop internal mixer equipped with a supercritical CO2 injection system. Inject supercritical CO2 into the internal mixer, control the system pressure to 10 MPa and the temperature to 60°C, and mix at 40 rpm for 5 minutes. After quickly depressurizing to remove CO2 and extracted VOCs, cool down to 45°C, add the composite vulcanization system of the above formula by weight, mix at 30 rpm for 2.5 minutes, and discharge the final rubber at a discharge temperature of 98°C. Low-stress preforming: The final rubber compound is passed through a two-roll mill at room temperature 4 times with a roll gap of 0.5 mm to eliminate internal stress in the rubber compound; then, it is extruded by a cold-feed precision extruder to obtain a preformed blank at an extrusion temperature of 50℃ and a screw speed of 20 rpm. The preformed blank is 2 mm thick and has a dimensional tolerance of ≤ ±0.05 mm. Photo-thermal dual-stage crosslinking vulcanization: The first stage is room temperature UV pre-crosslinking. The preform is placed in a vulcanization mold equipped with a UV irradiation module. Under normal pressure and room temperature conditions, a 365nm wavelength UV LED light source is used for irradiation at an intensity of 1000mW / cm² for 45s, constructing a uniformly distributed network of pre-crosslinked points within the rubber compound system. The second stage is gradient temperature thermal vulcanization. After mold closing, the vulcanization pressure is kept constant at 13MPa, and gradient temperature vulcanization is used. The total vulcanization time is 6.5min: the first stage is 140℃, vulcanization time 2.275min; the second stage is 155℃, vulcanization time 3.25min; and the third stage is 143℃, vulcanization time 0.975min. Full-chain VOC closed-loop control post-processing: The vulcanized products are immediately placed in a sealed oven with an integrated vacuum devolatilization + photocatalytic degradation device. First, they are devolatilized for 1.2 hours at a vacuum of -0.085MPa and a temperature of 90℃. The gas emitted after devolatilization is then treated in a photocatalytic degradation reactor before being discharged. Subsequently, the products are heat-treated for 1 hour at 80℃ and normal pressure to obtain the finished rubber products.

[0030] Example 2 Formula (parts by weight): 80 parts high cis BR, 20 parts SSBR, 35 parts modified silica, 7 parts reactive polyester plasticizer, 1.2 parts reactive antioxidant, 0.8 parts reactive dispersant, 1.2 parts insoluble sulfur IS-60, 0.3 parts accelerator TBzTD, 1.3 parts accelerator CBS, 2 parts active zinc oxide, and 1.5 parts stearic acid.

[0031] Process steps In-situ interfacial polymerization modification of filler: 35 parts of nano-silica and 3.5 parts of composite modification system (1.05 parts of KH560, 2.1 parts of HTBN, and 0.35 parts of DCP) were added to a high-speed mixer and vacuum dehydrated at 100℃ for 20 min. The mixture was then cooled to 88℃ and added to the composite modification system. The mixture was then subjected to in-situ polymerization reaction at 3500 rpm for 20 min to obtain modified silica with a flexible interfacial polymerization layer on the surface that can participate in sulfurization crosslinking. Supercritical CO2-assisted closed-loop one-step mixing: Take the base rubber, modified silica, reactive functional additive system, active zinc oxide, and stearic acid of the above formula by weight and put them into a closed-loop internal mixer equipped with a supercritical CO2 injection system. Inject supercritical CO2 into the internal mixer, control the system pressure to 9 MPa and the temperature to 58°C, and mix at 38 rpm for 6 minutes. After quickly depressurizing to remove CO2 and extracted VOCs, cool down to 42°C, add the composite vulcanization system of the above formula by weight, mix at 28 rpm for 3 minutes, and discharge the rubber to obtain the final rubber at a discharge temperature of 96°C. Low-stress preforming: The final rubber compound is passed through a two-roll mill three times with a roll gap of 0.6 mm to eliminate internal stress in the rubber compound; then, it is extruded by a cold-feed precision extruder to obtain a preformed blank at an extrusion temperature of 48℃ and a screw speed of 18 rpm. The preformed blank is 2 mm thick and has a dimensional tolerance of ≤ ±0.05 mm. Photo-thermal dual-stage vulcanization: The first stage involves room temperature UV pre-crosslinking, where the preform is placed in a vulcanization mold equipped with a UV irradiation module. Under normal pressure and room temperature conditions, a 365nm wavelength UV LED light source is used for irradiation at an intensity of 900mW / cm² for 50 seconds, constructing a uniformly distributed network of pre-crosslinked points within the rubber compound system. The second stage involves gradient temperature thermal vulcanization, where the vulcanization pressure is kept constant at 12MPa after mold closing. Gradient temperature vulcanization is employed, with a total vulcanization time of 7 minutes: the first stage at 139℃ for 2.45 minutes; the second stage at 153℃ for 3.5 minutes; and the third stage at 142℃ for 1.05 minutes. Full-chain VOC closed-loop control post-processing: The vulcanized products are immediately placed in a sealed oven with an integrated vacuum devolatilization + photocatalytic degradation device. First, they are devolatilized for 1.5 hours at a vacuum of -0.09MPa and a temperature of 88°C. The gas emitted after devolatilization is then treated in a photocatalytic degradation reactor before being discharged. Subsequently, the products are heat-treated for 1 hour at 80°C and normal pressure to obtain the finished rubber products.

[0032] Example 3 Formula (parts by weight): 60 parts high cis BR, 40 parts SSBR, 45 parts modified silica, 11 parts reactive polyester plasticizer, 1.8 parts reactive antioxidant, 1.2 parts reactive dispersant, 1.7 parts insoluble sulfur IS-60, 0.5 parts accelerator TBzTD, 1.7 parts accelerator CBS, 3 parts active zinc oxide, and 1 part stearic acid.

[0033] Process steps In-situ interfacial polymerization modification of filler: 45 parts of nano-silica and 5.4 parts of composite modification system (1.62 parts of KH560, 3.24 parts of HTBN, and 0.54 parts of DCP) were added to a high-speed mixer and vacuum dehydrated at 110℃ for 20 min. The temperature was then lowered to 92℃ and added to the composite modification system. The mixture was then subjected to in-situ polymerization reaction at 4000 rpm for 15 min to obtain modified silica with a flexible interfacial polymerization layer on the surface that can participate in sulfurization crosslinking. Supercritical CO2-assisted closed-loop one-step mixing: Take the base rubber, modified silica, reactive functional additive system, active zinc oxide, and stearic acid of the above formula by weight and put them into a closed-loop internal mixer equipped with a supercritical CO2 injection system. Inject supercritical CO2 into the internal mixer, control the system pressure to be 11 MPa and the temperature to be 62°C, and mix at 42 rpm for 4 min. After quickly depressurizing to remove CO2 and extracted VOCs, cool down to 48°C, add the composite vulcanization system of the above formula by weight, mix at 32 rpm for 2 min, and discharge the rubber to obtain the final rubber at a discharge temperature of 99°C. Low-stress preforming: The final rubber compound is passed through a two-roll mill four times with a roll gap of 0.4 mm to eliminate internal stress in the rubber compound; then, it is extruded by a cold-feed precision extruder to obtain a preformed blank at an extrusion temperature of 52℃ and a screw speed of 22 rpm. The preformed blank is 2 mm thick and has a dimensional tolerance of ≤ ±0.05 mm. Photo-thermal dual-stage vulcanization: The first stage involves room temperature UV pre-crosslinking, where the preform is placed in a vulcanization mold equipped with a UV irradiation module. Under normal pressure and room temperature conditions, a 365nm wavelength UV LED light source is used for irradiation at an intensity of 1100mW / cm² for 40 seconds, constructing a uniformly distributed network of pre-crosslinked points within the rubber compound system. The second stage involves gradient temperature thermal vulcanization, where the vulcanization pressure is kept constant at 14MPa after mold closing. Gradient temperature vulcanization is employed, with a total vulcanization time of 6 minutes: the first stage at 141℃ for 2.1 minutes; the second stage at 156℃ for 3 minutes; and the third stage at 144℃ for 0.9 minutes. Full-chain VOC closed-loop control post-processing: The vulcanized products are immediately placed in a sealed oven with an integrated vacuum devolatilization + photocatalytic degradation device. First, they are devolatilized for 1 hour at a vacuum of -0.08MPa and a temperature of 92℃. The gas emitted after devolatilization is treated in a photocatalytic degradation reactor before being discharged. Then, they are heat-treated for 1 hour at 80℃ and normal pressure to obtain the finished rubber products.

[0034] Scale settings Comparative Example 1: Traditional conventional process, formula is the same as in Example 1, using ordinary unmodified silica, traditional one-stage mixing for 15 min, constant temperature vulcanization at 150℃ for 12 min, natural cooling, no VOC post-treatment.

[0035] Comparative Example 2: Existing high-end process (mainstream high-end solution in the industry), the formula is the same as that of Example 1, using KH550 coupling agent to modify fumed silica, two-stage internal mixing, constant temperature vulcanization at 150℃ for 10 min, ordinary oven heat treatment + activated carbon adsorption.

[0036] Comparative Example 3: Only in-situ modified silica was used, while other processes were carried out using traditional methods (no supercritical mixing, no light-heat two-stage sulfidation).

[0037] Comparative Example 4: Only supercritical CO2 mixing was used, while other processes were traditional (no in-situ modification, no light-heat two-stage vulcanization).

[0038] Comparative Example 5: Only light-heat two-stage vulcanization was used, while other processes were carried out using traditional methods (no in-situ modification, no supercritical mixing).

[0039] Performance test comparison All samples were tested according to national / international standards, and the test results are shown in the table below:

[0040] Key conclusions from the test results: The performance of each embodiment of the present invention has been significantly improved, with wear resistance increased by more than 350% and dynamic fatigue life increased by more than 300% compared with traditional processes, and VOC content reduced by more than 90%, fully achieving the intended purpose of the invention. The performance improvement of Comparative Examples 3-5 is far less than that of the Examples, proving that there is a significant synergistic effect among the four innovative modules of the present invention, which is not a simple superposition of technologies. It has outstanding substantive features and significant progress, and meets the inventiveness requirements of an invention patent. This invention completely solves the three core contradictions of traditional processes: "reinforcement and elasticity, environmental protection and performance, and efficiency and quality," and achieves a significant improvement in the performance of rubber products.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A manufacturing process for near-zero VOC ultra-abrasion-resistant rubber products with dual-network crosslinking, characterized in that, Includes the following steps: S1. In-situ interfacial polymerization modification of filler: Nano-silica is added to a high-speed mixer and vacuum dehydrated at 100-110℃ for 20 min; then cooled to 85-95℃ and added to a composite modification system. In-situ polymerization reaction is carried out at 3500-4000 rpm for 15-20 min to obtain modified silica with a flexible interfacial polymerization layer on the surface that can participate in sulfurization crosslinking. S2. Supercritical CO2-assisted closed-loop one-step mixing: Take 100 parts by weight of base rubber, 30-50 parts of modified silica, reactive functional additive system, 2-3 parts of active zinc oxide, and 1-1.5 parts of stearic acid and put them into a closed-loop mixer equipped with a supercritical CO2 injection system; inject supercritical CO2 into the mixer, control the system pressure at 8-12 MPa and the temperature at 55-65℃, and mix at 35-45 rpm for 4-6 minutes; quickly depressurize to remove CO2 and extracted VOCs, cool to 40-50℃ and then add the composite vulcanization system, mix at 25-35 rpm for 2-3 minutes, and discharge the rubber to obtain the final rubber. The discharge temperature is controlled at ≤100℃. S3, Low-stress preforming: The final rubber compound is passed through a two-roll mill at room temperature 3 to 4 times, with the roll gap controlled at 0.3 to 0.8 mm, to eliminate internal stress in the rubber compound; then it is extruded through a cold-feed precision extruder to obtain a preformed blank, with an extrusion temperature of 45 to 55°C and a screw speed of 15 to 25 rpm. S4, photo-thermal dual-stage crosslinking vulcanization: S41. Room temperature UV pre-crosslinking: The preformed blank is placed in a vulcanization mold with a UV irradiation module. Under normal pressure and room temperature conditions, a UV LED light source with a wavelength of 365nm is used for irradiation, with an irradiation intensity of 800~1200mW / cm² and an irradiation time of 30~60s, to construct a uniformly distributed network of pre-crosslinking points in the rubber system. S42. Three-stage gradient temperature vulcanization: After mold closing, maintain a constant vulcanization pressure of 12-15 MPa and adopt gradient temperature vulcanization. The first stage is vulcanization at 138-142℃, with a vulcanization time of 35% of the total vulcanization time; the second stage is vulcanization at 152-156℃, with a vulcanization time of 50% of the total vulcanization time; the third stage is vulcanization at 142-145℃, with a vulcanization time of 15% of the total vulcanization time. S5. Full-chain VOC closed-loop control post-processing: The vulcanized products are immediately placed in a sealed oven equipped with an integrated vacuum devolatilization + photocatalytic degradation device. First, they are devolatilized at a vacuum degree of -0.08 to -0.09 MPa and a temperature of 85 to 95°C for 1 to 1.5 hours. The gas emitted from the devolatilization is then treated in a photocatalytic degradation reactor before being discharged. Subsequently, the products are heat-treated at atmospheric pressure and 80°C for 1 hour to eliminate internal stress and obtain finished rubber products.

2. The production process according to claim 1, characterized in that, In step S1, the composite modification system is a mixture of silane coupling agent KH560, hydroxyl-terminated butadiene-acrylonitrile rubber HTBN, and initiator dicumyl peroxide DCP in a mass ratio of 3:6:1, and the amount added is 8%-12% of the mass of silica.

3. The production process according to claim 1, characterized in that, The base rubber is a blend of 60-80 parts of high cis-butadiene rubber BR and 20-40 parts of solution-polymerized styrene-butadiene rubber SSBR, with a Mooney viscosity ML(1+4)100℃ = 45-55.

4. The production process according to claim 1, characterized in that, In step S1, the thickness of the flexible interface polymer layer on the surface of the modified silica is 5-10 nm. One end of the interface layer is covalently bonded to the surface of the silica through silicon-oxygen bonds, and the other end has double bonds and epoxy groups that can participate in the sulfidation reaction.

5. The production process according to claim 1, characterized in that, In step S2, the supercritical CO2 is recycled with a rate of ≥95% after condensation and recovery, and the VOCs discharged from the pressure relief system simultaneously enter the photocatalytic degradation system, eliminating fugitive emissions.

6. The production process according to claim 1, characterized in that, The reactive functional additive system comprises, by weight, 6-12 parts of epoxy-based reactive polyester plasticizer, 1-2 parts of reactive hindered amine antioxidant, and 0.8-1.5 parts of reactive dispersant. All components of the reactive functional additive system can participate in the vulcanization crosslinking reaction.

7. The production process according to claim 1, characterized in that, The composite vulcanization system, by weight, includes 1.0 to 1.8 parts of insoluble sulfur IS-60, 0.3 to 0.6 parts of accelerator TBzTD, and 1.2 to 1.8 parts of accelerator CBS.

8. The production process according to claim 1, characterized in that, In step S4, the total vulcanization time for the 2mm thick product is 6-7 minutes.

9. The production process according to claim 1, characterized in that, In step S5, photocatalytic degradation uses ultraviolet light with a wavelength of 254 nm in combination with a nano-TiO2 catalyst, and the VOC degradation rate is ≥99.9%.

10. A near-zero VOC ultra-abrasion resistant rubber product prepared by the production process according to any one of claims 1-9.

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