Low exhaust emission acrylic sheet environmental protection manufacturing process

Abstract

The present application belongs to the technical field of high molecular compound, and particularly relates to an environment-friendly manufacturing process of acrylic sheet with low waste gas emission. The process comprises the following steps: recycling waste acrylic sheet, cleaning and cutting the acrylic sheet into cracking raw materials; filling raw material gas into a substrate polymerization cavity and sealing, stirring and positive and negative pressure fluctuation circulation; heating and controlling pressure to make the raw materials preliminarily polymerize and form cracking polymerization plates, and stacking the formed plates in multiple layers; taking the plates by a gas extraction device and sending them into a cracking cavity to replace the raw materials for cracking, and setting a periodic cycle; after completing exhaust and glue removal in the polymerization cavity, filling polymerization gas to perform laminating and forming, and finally obtaining acrylic sheet blanks, and forming finished acrylic sheet by hot cutting and trimming; and setting a waste gas recovery system to condense and filter the waste gas, and recycling methacrylic acid and methanol. The process effectively reduces waste gas emission, improves raw material utilization and product quality, and is suitable for continuous and large-scale production of environment-friendly acrylic sheet.

Description

Technical Field

[0001] This invention belongs to the technical field of polymer compounds, specifically an environmentally friendly manufacturing process for acrylic sheets with low emissions. Background Technology

[0002] Acrylic sheets, typically referring to polymethyl methacrylate (PMMA) sheets, possess excellent transparency, weather resistance, and processability, and are widely used in architectural decoration, advertising signage, transportation, medical equipment, and other fields. Existing acrylic sheet manufacturing processes mainly include two categories: casting and extrusion. Casting is more widely used due to its higher product quality.

[0003] Traditional acrylic sheet manufacturing processes typically involve the polymerization of methyl methacrylate (MMA), a monomer that requires large amounts of initiators, solvents, and other auxiliary additives. These materials readily generate volatile organic compounds (VOCs) and other harmful gases, such as benzene compounds, formaldehyde, and small amounts of unreacted monomers, during polymerization, molding, and post-processing. These waste gases not only pollute the production environment but also pose a threat to the health of operators and increase the cost of emission control and compliance.

[0004] To reduce emissions, some existing technologies have been developed that optimize raw material formulations, improve polymerization reaction conditions, employ closed reaction systems, and add waste gas treatment devices. However, these technologies still have the following shortcomings:

[0005] Although some processes control exhaust emissions, the polymerization reaction itself still uses a large amount of traditional monomers and additives, making it difficult to effectively reduce emissions at the source. Some environmentally friendly acrylic sheet manufacturing processes often sacrifice the transparency, impact resistance, or mechanical properties of the products while reducing exhaust emissions, making it difficult to meet both environmental protection requirements and product quality needs.

[0006] Therefore, how to provide an environmentally friendly manufacturing process that can effectively control exhaust emissions at the source, take into account the performance indicators of acrylic sheets, and is simple to process and suitable for large-scale production has become an urgent technical problem to be solved in this field. Summary of the Invention

[0007] To address the aforementioned problems in the existing technology, the present invention aims to provide an environmentally friendly manufacturing process for acrylic sheets with low exhaust emissions, comprising the following steps:

[0008] S1. Waste board recycling: Recycling discarded acrylic boards;

[0009] S2, Pyrolysis Polymerization: The substrate polymerization chamber is filled, sealed, and stirred with raw material gas, and positive and negative pressure fluctuations are circulated.

[0010] S3, Molding substrate: After the raw material gas treatment is completed, the raw material is initially polymerized and shaped in the polymerization chamber by heating and controlling the pressure to obtain a cracked polymer board with a certain thickness and strength.

[0011] S4. Stack the formed pyrolysis polymerization plates in multiple layers: After taking out the formed pyrolysis polymerization plates, stack them in multiple layers in a predetermined order to prepare for subsequent replacement raw material pyrolysis and lamination polymerization operations.

[0012] S5. Replacement raw material pyrolysis: Material is taken from the material pool of the gas extraction device and sent into the pyrolysis chamber. The slurry is submerged under negative pressure for pre-pyrolysis, and positive and negative pressure fluctuation stirring is carried out simultaneously to promote the reaction.

[0013] S6. Cyclic cycle: Some of the material in the molten pool is precipitated into the sedimentation tank. After the material is extracted to the preset height, return to step S5 to perform at least five cycles of replacement raw material pyrolysis and sedimentation gas extraction.

[0014] S7. Exhausting and removing adhesive: The final pre-pyrolysis gas in the polymerization chamber is exhausted through the external exhaust valve;

[0015] S8. Polymerization molding and lamination: Polymerization gas is filled into the polymerization cavity of the substrate, and after polymerization, molding and degassing and de-adhesive removal operations, acrylic sheet molding is obtained.

[0016] S9. Finishing: Hot-cut the acrylic sheet to obtain the target finished acrylic sheet;

[0017] S10, Waste gas recovery and cracking recovery of methacrylic acid and methanol: The gas in the polymerization chamber is drawn into the waste gas recovery device for treatment.

[0018] Furthermore, the recycling of waste acrylic sheets in step S1 specifically includes: recycling the used waste acrylic sheets, performing cleaning and decontamination operations to remove stains and adhering substances from the surface of polymethyl methacrylate, and using cutting equipment to cut the whole waste acrylic sheet into strips of preset size for pyrolysis raw materials.

[0019] Furthermore, step S5 specifically includes the following steps:

[0020] S51. Cut and extract material from the material pool of the gas extraction device and send it into the pyrolysis chamber inside the gas extraction device;

[0021] S52, Sinking into slurry: While performing the substrate molding operation, open the second valve of the valve group to sink the material in the molten pool into the pyrolysis chamber in the gas extraction device under negative pressure.

[0022] S53, Pre-pyrolysis: Pre-pyrolyze the gaseous substances in the polymerization chamber, so that the pre-pyrolyzed gas enters the polymerization chamber through the gas inlet valve;

[0023] S54. Positive and negative pressure stirring: During pre-pyrolysis, the air pump is controlled to perform positive and negative pressure fluctuation stirring on the polymerization chamber.

[0024] Furthermore, the positive and negative pressure fluctuation stirring in step S54 specifically includes:

[0025] S541: Maintain the internal pressure of the polymerization chamber at 1 / 3 of the external air pressure, and inject the pre-pyrolysis gas in the pyrolysis chamber into the polymerization chamber at a preset flow rate;

[0026] S542: When the pressure inside the polymerization chamber reaches three times the external air pressure, open the air outlet and output the excess pre-pyrolysis gas into the pyrolysis chamber at a first preset flow rate;

[0027] S543: When the gas pressure inside the polymerization chamber drops to 1 / 3 of the external gas pressure, close the gas outlet and repeat steps S541 and S542.

[0028] Furthermore, in step S6, some of the material in the molten pool is precipitated into a sedimentation tank, and positive and negative pressure stirring is used to control the positive and negative pressure ratio to be 1:3.

[0029] Furthermore, in step S10, the gas in the polymerization chamber is drawn into the waste gas recovery device for treatment. Specifically, the waste gas is filtered and condensed in the waste gas recovery device, and then methacrylic acid and methanol are cracked and recovered to produce polymethyl methacrylate.

[0030] Furthermore, the polymerization molding lamination in step S8 specifically includes: applying adhesive to the surfaces of two or more polymer plates, placing the polymer plates in a heated pressing tank while they are in contact with each other, heating them to 120°C at a heating rate of 4°C / min, and performing degassing and pressing operations simultaneously with heating.

[0031] Furthermore, the process of venting and pressing while heating specifically includes: venting excess gas from the substrate polymerization chamber at a preset speed, and slowly pressurizing at 0.2 MPa. When the pressure inside the polymerization chamber reaches 1 / 4 of the external air pressure, pressurization and venting are stopped to maintain a constant internal pressure in the polymerization chamber.

[0032] This invention also provides an environmentally friendly acrylic sheet manufacturing equipment with low exhaust emissions, used to implement the aforementioned environmentally friendly acrylic sheet manufacturing process with low exhaust emissions, the equipment comprising:

[0033] Waste gas recovery device: The waste gas recovery device is used to collect the generated waste gas;

[0034] Substrate polymerization chamber: The substrate polymerization chamber is used for polymerization of raw material gas, degassing and degumming, and multi-layer board polymerization molding. The substrate polymerization chamber is equipped with a stirring paddle for positive and negative pressure fluctuation stirring of the internal gas. The substrate polymerization chamber is also equipped with an inlet valve and an outlet valve.

[0035] Gas extraction device: The gas extraction device includes a pyrolysis chamber and a polymerization chamber;

[0036] The pyrolysis chamber is equipped with a valve group, which includes a first valve and a second valve connected to the gas inlet valve, for introducing the pre-pyrolysis gas generated in the pyrolysis chamber into the substrate polymerization chamber;

[0037] The polymerization chamber is used for polymerization extraction and separation of impurities. The polymerization chamber is provided with an air outlet. The air outlet is connected to the air inlet valve of the substrate polymerization chamber through a pipeline. An air pump is provided at the air outlet.

[0038] Cutting chamber: The cutting chamber includes an opening and closing cover and an inlet and an outlet provided on the opening and closing cover. Both the inlet and the outlet are provided with air lock valves. A cutting tool is provided inside the cutting chamber.

[0039] Furthermore, the waste gas recovery device is equipped with a return pipeline, which is connected to the substrate polymerization chamber. The waste gas recovery device extracts polymethyl methacrylate from the waste gas according to a preset ratio and inputs it into the substrate polymerization chamber.

[0040] Beneficial effects

[0041] This invention provides an environmentally friendly manufacturing process and supporting equipment for acrylic sheets with low exhaust emissions. Addressing the problems of high exhaust emissions, significant environmental pressure, and high energy consumption in existing acrylic sheet production processes, it proposes a comprehensive solution combining source control and process optimization, offering the following beneficial effects:

[0042] 1. Significantly reduced exhaust emissions: By adopting steps such as waste board recycling, pyrolysis polymerization, pre-pyrolysis gas treatment, and positive and negative pressure fluctuation stirring, the raw materials are efficiently pyrolyzed and reused, which greatly reduces the emissions of volatile organic compounds (VOCs) such as methyl methacrylate, meeting the requirements of green and environmentally friendly production.

[0043] 2. Improve raw material utilization: This invention maximizes the recovery of methacrylic acid and methanol by pyrolyzing and recycling waste acrylic sheets, reducing the need for new raw materials, lowering raw material costs, and improving resource utilization efficiency.

[0044] 3. Improve finished product quality: In the molding substrate and multi-layer stacking stages, optimized heating rate and positive and negative pressure control processes are adopted to effectively avoid common defects such as bubbles and cracks, ensuring the excellent transparency, mechanical properties and dimensional stability of acrylic sheets.

[0045] 4. Continuous and efficient process flow: By setting up periodic replacement of raw material cracking and precipitation extraction steps, and simultaneously carrying out degassing and pressing during the polymerization molding process, continuous and automated production can be achieved, which improves production efficiency and shortens the board making cycle.

[0046] In summary, this invention has achieved significant technical results in reducing exhaust emissions, improving resource utilization, ensuring the performance of acrylic sheet products, and optimizing production costs and efficiency. It has good prospects for promotion and application and market competitiveness. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0048] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0049] Example 1

[0050] according to Figure 1 As shown, this embodiment provides an environmentally friendly manufacturing process for acrylic sheets with low exhaust emissions, including the following steps:

[0051] S1. Waste board recycling: The used waste acrylic boards are recycled, cleaned and decontaminated to remove stains and adhering substances from the surface of polymethyl methacrylate, and the whole waste acrylic board is cut into strips of preset size pyrolysis raw materials using cutting equipment.

[0052] S2, Pyrolysis Polymerization: The substrate polymerization chamber is filled, sealed, and stirred with raw material gas, and positive and negative pressure fluctuations are circulated.

[0053] S3, Molding substrate: After the raw material gas treatment is completed, the raw material is initially polymerized and shaped in the polymerization chamber by heating and controlling the pressure to obtain a cracked polymer board with a certain thickness and strength.

[0054] S4. Stack the formed pyrolysis polymerization plates in multiple layers: After taking out the formed pyrolysis polymerization plates, stack them in multiple layers in a predetermined order to prepare for subsequent replacement raw material pyrolysis and lamination polymerization operations.

[0055] S5. Replacement raw material pyrolysis: Material is taken from the material pool of the gas extraction device and sent into the pyrolysis chamber. The slurry is submerged under negative pressure for pre-pyrolysis, and positive and negative pressure fluctuation stirring is carried out simultaneously to promote the reaction.

[0056] S6. Cyclic cycle: Some of the material in the molten pool is precipitated into the sedimentation tank. After the material is extracted to the preset height, return to step S5 to perform at least five cycles of replacement raw material pyrolysis and sedimentation gas extraction.

[0057] S7. Exhausting and removing adhesive: The final pre-pyrolysis gas in the polymerization chamber is exhausted through the external exhaust valve;

[0058] S8. Polymerization molding and lamination: Polymerization gas is filled into the polymer cavity of the substrate. After polymerization, molding and degassing and de-adhesive removal operations, an acrylic sheet molded board is obtained. Adhesive is applied to the surfaces of two or more polymer boards. The polymer boards are placed in a heating and pressing tank with the boards in a mutually bonded state. The temperature is raised to 120°C at a heating rate of 4°C / min. Degassing and pressing operations are performed simultaneously with heating.

[0059] S9. Finishing: Hot-cut the acrylic sheet to obtain the target finished acrylic sheet;

[0060] S10, Waste gas recovery and cracking recovery of methacrylic acid and methanol: The gas in the polymerization chamber is drawn into the waste gas recovery device for treatment.

[0061] Example 2

[0062] This embodiment further defines the limitations based on Embodiment 1:

[0063] Step S5 specifically includes the following steps:

[0064] S51. Cut and extract material from the material pool of the gas extraction device and send it into the pyrolysis chamber inside the gas extraction device;

[0065] S52, Sinking into slurry: While performing the substrate molding operation, open the second valve of the valve group to sink the material in the molten pool into the pyrolysis chamber in the gas extraction device under negative pressure.

[0066] S53, Pre-pyrolysis: Pre-pyrolyze the gaseous substances in the polymerization chamber, so that the pre-pyrolyzed gas enters the polymerization chamber through the gas inlet valve;

[0067] S54, Positive and Negative Pressure Stirring: During pre-pyrolysis, the air pump is controlled to perform positive and negative pressure fluctuation stirring on the polymerization chamber; the positive and negative pressure fluctuation stirring in step S54 specifically includes:

[0068] S541: Maintain the internal pressure of the polymerization chamber at 1 / 3 of the external air pressure, and inject the pre-pyrolysis gas in the pyrolysis chamber into the polymerization chamber at a preset flow rate;

[0069] S542: When the pressure inside the polymerization chamber reaches three times the external air pressure, open the air outlet and output the excess pre-pyrolysis gas into the pyrolysis chamber at a first preset flow rate;

[0070] S543: When the gas pressure inside the polymerization chamber drops to 1 / 3 of the external gas pressure, close the gas outlet and repeat steps S541 and S542.

[0071] Example 3

[0072] This embodiment provides an environmentally friendly manufacturing process for acrylic sheets with low exhaust emissions. The process mainly relies on the recycling of waste acrylic sheets. Through an optimized pyrolysis polymerization and lamination molding process, polymethyl methacrylate (PMMA) material is regenerated and prepared. By controlling the positive and negative pressure of the entire process system and the exhaust gas recovery mechanism, the amount of organic waste gas emissions is significantly reduced, thereby improving overall production efficiency and environmental friendliness.

[0073] Specifically, the process includes the following steps:

[0074] S1, Recycling waste boards

[0075] First, the waste acrylic sheets generated during use are sorted and recycled. Sheets with oil, dust, coatings, and other impurities on their surfaces are sequentially fed into a cleaning device, where they are scrubbed using a weak alkaline solution and soft brushes. After cleaning, the waste sheets are dried with hot air in a drying device to remove residual moisture and ensure no moisture interference in subsequent operations.

[0076] Subsequently, the dried waste board is resized using intelligent cutting equipment. According to process requirements, the whole acrylic board is cut into strips of about 100mm×100mm for pyrolysis raw materials, so that they can be subsequently fed into the gas pyrolysis system for pyrolysis and polymerization.

[0077] S2, pyrolysis polymerization

[0078] The pyrolysis feedstock, after being cut, is sequentially fed into the substrate polymerization chamber via a feeding valve. The chamber is then sealed using an airtight system. Subsequently, the stirring mechanism is activated to begin low-speed, uniform stirring of the feedstock within the chamber. Simultaneously, the air pump is controlled to implement a positive and negative pressure fluctuation cycle, gradually increasing the pressure inside the polymerization chamber from one-third of the external pressure to three times the external atmospheric pressure, then rapidly releasing it back to the initial state, forming a complete pressure fluctuation process. This cycle is repeated 3–5 times, which helps to decompose impurities and residual gases in the polymerization chain segments in advance, promoting the uniformity of subsequent polymerization reactions.

[0079] S3, molding substrate

[0080] After the pyrolysis polymerization is completed, constant heating is applied to the inside of the polymerization chamber. The temperature is steadily raised to 85℃-95℃ using a temperature control device and maintained for 20-30 minutes, allowing the raw materials to complete the initial polymerization under the combined effects of pressure and temperature. During the polymerization process, the raw materials are deposited layer by layer at the bottom of the chamber to form a polymer of a certain thickness, becoming a pyrolysis polymerization plate with basic strength. The thickness of this plate can be set according to the required finished plate specifications, typically 3mm to 6mm.

[0081] S4, multi-layer stacking

[0082] The pre-cured pyrolysis polymerized plates in the polymerization chamber are removed by a robotic arm and stacked according to a pre-set layering sequence. During stacking, a suitable amount of high-temperature adhesive is sprayed between the plates to ensure bonding and polymerization between the multiple layers. After the multi-layer stacking is completed, the entire slab enters the processing area, ready to proceed to the next round of replacement raw material pyrolysis.

[0083] S5, Replacement raw material pyrolysis

[0084] This step consists of the following sub-steps:

[0085] S51: By controlling the cutting device, new pyrolysis feedstock strips are cut from the material pool of the gas extraction device and sent into the pyrolysis chamber of the gas extraction device via a closed conveyor belt.

[0086] S52: While the substrate is being molded, the second valve is opened, and the slurry-like reactants in the molten pool are drawn out by the negative pressure pump and sucked into the pyrolysis chamber for mixing.

[0087] S53: The built-in heating element is used to preheat the pyrolysis chamber, so that the original gaseous substances in the polymerization chamber begin to pyrolyze when the temperature is raised to 120°C, releasing the pre-pyrolyzed gas;

[0088] S54: Control the air pump to start positive and negative pressure oscillation stirring to fully mix the pre-pyrolysis gas. During the oscillation stirring operation, the pressure inside the polymerization chamber cyclically changes between 1 / 3 of the external gas pressure and 3 times the external gas pressure.

[0089] S6, Cyclic Loop

[0090] After one replacement pyrolysis cycle, the pyrolysis residue is piped into a settling tank, where heavy materials precipitate out through sedimentation. Alternating positive and negative pressure stirring technology ensures thorough sedimentation. A height sensor is installed; when the slurry level in the settling tank reaches a set height, it is automatically extracted and returned to the pyrolysis chamber, repeating step S5. The entire process is continuously cyclical at least five times to ensure complete reaction and product purity.

[0091] S7, Exhaust and Degumming

[0092] After the cycle of pyrolysis is completed, the external vent valve is opened to quickly remove the remaining pre-pyrolysis gas from the polymerization chamber, and the chamber is then evacuated under vacuum. This step prevents defects such as blistering and adhesive residue on the boards caused by residual gas.

[0093] S8, Polymerization Molding Lamination

[0094] The multi-layered polymer boards are fed into a heated pressing tank to begin polymerization. Polymerization gas is introduced into the polymerization chamber through an inlet valve, and the reaction is completed as the internal temperature rises from room temperature to 120°C at a rate of 4°C / min. Simultaneously, vacuum degassing and slow pressurization at 0.2 MPa are implemented to ensure uniform diffusion of the adhesive between the multi-layer boards and to achieve dense lamination and curing. The control system judges the reaction progress based on the gas pressure value. When the internal pressure of the polymerization chamber is maintained at a constant level of 1 / 4 of the external gas pressure, it remains unchanged to ensure molding stability.

[0095] S9, Repair

[0096] After molding, the acrylic sheet is sent to the hot-cutting area and cut to the set dimensions using precision cutting equipment. Depending on the application, it can be cut into rectangular sheets, round sheets, or other custom-sized sheets. The trimmed sheets then enter the finished product inspection area for testing parameters such as thickness, gloss, impact resistance, and transparency.

[0097] S10, Waste Gas Recovery and Pyrolysis Reuse

[0098] Gases emitted at each stage of the process are collected via pipelines to a waste gas recovery unit. This unit includes a condensation unit, a filtration module, and a return pipeline. The condensation system condenses and recovers methacrylic acid and methanol from the waste gas, and then uses a catalytic reaction device to resynthesize them into polymethyl methacrylate monomers for subsequent production. Uncondensed tail gas is treated by adsorption in the filtration module to meet emission standards. Some recyclable materials are returned to the polymerization chamber via the return pipeline, further improving the system's closed-loop efficiency and environmental friendliness.

[0099] In summary, this embodiment provides a highly efficient, environmentally friendly, and closed-loop method for manufacturing acrylic sheets by integrating raw material pyrolysis, polymerization reaction, lamination molding, and waste gas recovery technologies. It offers advantages such as low emissions, low cost, and high quality, making it suitable for widespread application in modern materials processing industries. This process not only improves waste recycling efficiency but also significantly reduces volatile organic compound (VOC) emissions, meeting the requirements of green manufacturing and sustainable development.

[0100] Example 4

[0101] In this embodiment, the equipment includes a waste gas recovery device, a substrate polymerization chamber, a gas extraction device, and a cutting chamber. The components are organically connected through pipes, gas valves, and a control system to form a continuous, closed-loop operation process.

[0102] 1. Waste gas recovery device

[0103] The waste gas recovery device is used to collect and treat waste gas generated during the manufacturing process, preventing the direct emission of volatile organic compounds (VOCs) into the environment. It specifically includes a condensation unit, a filtration unit, and a return pipeline system. The waste gas first passes through the condensation module, where components such as methacrylic acid and methanol are liquefied and recovered under low-temperature conditions. The uncondensed exhaust gas then enters a multi-layer filtration module, where it is further purified through processes such as activated carbon adsorption or catalytic decomposition. The purified gas emissions meet national environmental protection standards.

[0104] The waste gas recovery device is equipped with a return pipeline connected to the substrate polymerization chamber. The recovered and extracted methyl methacrylate monomer is reintroduced into the substrate polymerization chamber in a certain proportion for subsequent pyrolysis polymerization operations, thereby achieving raw material recycling and reducing production costs and raw material consumption.

[0105] 2. Substrate polymerization cavity

[0106] The substrate polymerization chamber is the core component for the main polymerization reaction and sheet forming. The internal space of the polymerization chamber is enclosed, resistant to high temperatures and corrosion, and can withstand high-intensity positive and negative pressure fluctuations. An agitator is installed inside the chamber, connected to an external motor via a central drive shaft, enabling timed, speed-controlled, and adjustable stirring to ensure uniform mixing of gas and initial polymer within the chamber, preventing incomplete polymerization or bubble formation.

[0107] The top of the polymerization chamber is equipped with an inlet valve and an outlet valve. The inlet valve is connected to a gas extraction device to receive pre-pyrolysis gases, while the outlet valve is connected to a waste gas recovery device to promptly remove gaseous impurities generated during the reaction and maintain a stable atmosphere within the chamber. Furthermore, the chamber is equipped with pressure and temperature sensors to monitor the internal status in real time and link with the central control system for precise adjustment of polymerization reaction parameters.

[0108] The substrate polymerization chamber is also equipped with a glue discharge port. At the end of the polymerization process, the residual gas and glue residue in the chamber are discharged through an external vent valve to further ensure the purity and surface smoothness of the board.

[0109] 3. Gas extraction device

[0110] The gas extraction device consists of two parts: a pyrolysis chamber and a polymerization chamber, which are connected to each other through built-in channels.

[0111] Pyrolysis Chamber: The pyrolysis chamber is used for the preliminary thermal pyrolysis of the cut waste board raw material. A heating module is installed inside the pyrolysis chamber, which raises the chamber temperature to 120℃~150℃ through electric heating or external steam heating, causing the polymer chain segments in the raw material to break down and releasing methyl methacrylate monomer and a small amount of auxiliary components. A valve assembly is installed on the pyrolysis chamber, including a first valve and a second valve. The first valve controls the discharge of pyrolysis gas, and the second valve is directly connected to the inlet valve of the substrate polymerization chamber, used to introduce the generated pre-pyrolysis gas into the polymerization chamber for further polymerization reaction.

[0112] Polymerization Chamber: The polymerization chamber within the gas extraction device assists in gas polymerization and impurity extraction and separation. The pre-pyrolyzed gas is further heated and stirred within the polymerization chamber, causing unreacted monomers to separate from light impurities. The light gas is discharged through the outlet to the waste gas recovery device, while the effective monomers smoothly enter the substrate polymerization chamber to complete polymerization and molding.

[0113] The gas extraction device is also equipped with an air pump, which is installed at the air outlet to provide the necessary gas flow power during the switching between positive and negative pressure, ensuring the continuous and stable extraction and transmission process.

[0114] 4. Cutting cavity

[0115] The cutting chamber is used for preliminary dimensional processing of recycled waste acrylic sheets to ensure the efficiency of subsequent pyrolysis operations and the quality of the finished product. The cutting chamber has a compact structure, good sealing, and is equipped with high-precision cutting tools that can perform strip or sheet cutting operations according to a set program.

[0116] The cutting chamber includes a hinged cover with an inlet and an outlet for easy loading and unloading of raw materials. To prevent gas leakage or impurities from entering, both the inlet and outlet are equipped with airlock valves, which are linked to the central control system to ensure stable pressure during switching and prevent gas contamination or energy loss during operation.

[0117] The cut raw materials can be directly fed into the gas extraction unit through a closed conveyor system, forming a continuous operation chain and improving overall production efficiency.

[0118] The foregoing has shown and described 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 to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An environmentally friendly manufacturing process for acrylic sheets with low exhaust emissions, characterized in that, Implementation based on environmentally friendly acrylic sheet manufacturing equipment with low exhaust emissions; The device includes: Waste gas recovery device; the waste gas recovery device is used to collect the generated waste gas; Substrate polymerization chamber: The substrate polymerization chamber is used for polymerization of raw material gas, degassing and degumming, and multi-layer board polymerization molding. The substrate polymerization chamber is equipped with a stirring paddle for positive and negative pressure fluctuation stirring of the internal gas. The substrate polymerization chamber is also equipped with an inlet valve and an outlet valve. Gas extraction device: The gas extraction device includes a pyrolysis chamber and a polymerization chamber; The pyrolysis chamber is equipped with a valve group, which includes a first valve and a second valve connected to the gas inlet valve, for introducing the pre-pyrolysis gas generated in the pyrolysis chamber into the substrate polymerization chamber; The polymerization chamber is used for polymerization extraction and separation of impurities. The polymerization chamber is provided with an air outlet. The air outlet is connected to the air inlet valve of the substrate polymerization chamber through a pipeline. An air pump is provided at the air outlet. Cutting chamber: The cutting chamber includes an opening and closing cover and an inlet and an outlet provided on the opening and closing cover. Both the inlet and the outlet are provided with air lock valves. A cutting tool is provided inside the cutting chamber. The manufacturing process includes the following steps: S1. Waste board recycling: Recycling discarded acrylic boards; S2, Pyrolysis Polymerization: The substrate polymerization chamber is filled, sealed, and stirred with raw material gas, and positive and negative pressure fluctuations are circulated. S3, Molding substrate: After the raw material gas treatment is completed, the raw material is initially polymerized and shaped in the polymerization chamber by heating and controlling the pressure to obtain a cracked polymer board with a certain thickness and strength. S4. Stack the formed pyrolysis polymerization plates in multiple layers: After taking out the formed pyrolysis polymerization plates, stack them in multiple layers in a predetermined order to prepare for subsequent replacement raw material pyrolysis and lamination polymerization operations. S5. Replacement raw material pyrolysis: Material is taken from the material pool of the gas extraction device and sent into the pyrolysis chamber. The slurry is submerged under negative pressure for pre-pyrolysis, and positive and negative pressure fluctuation stirring is carried out simultaneously to promote the reaction. S6. Cyclic cycle: Some of the material in the molten pool is precipitated into the sedimentation tank. After the material is extracted to the preset height, return to step S5 to perform at least five cycles of replacement raw material pyrolysis and sedimentation gas extraction. S7. Exhaust and remove adhesive: Exhaust the last pre-cracked gas in the polymerization chamber through the external exhaust valve; S8. Polymerization molding and lamination: Polymerization gas is filled into the polymerization cavity of the substrate, and after polymerization, molding and degassing and de-adhesive removal operations, acrylic sheet molding is obtained. S9. Finishing: Hot-cut the acrylic sheet to obtain the target finished acrylic sheet; S10, Waste gas recovery and cracking recovery of methacrylic acid and methanol: The gas in the polymerization chamber is drawn into the waste gas recovery device for treatment.

2. The environmentally friendly manufacturing process for low-emission acrylic sheets according to claim 1, characterized in that, The recycling of waste acrylic sheets in step S1 specifically includes: recycling the used waste acrylic sheets, cleaning and decontamination operations to remove stains and adhering substances from the surface of polymethyl methacrylate, and using cutting equipment to cut the whole waste acrylic sheet into strips of preset size for pyrolysis raw materials.

3. The environmentally friendly manufacturing process for low-emission acrylic sheets according to claim 1, characterized in that, Step S5 specifically includes the following steps: S51. Cut and extract material from the material pool of the gas extraction device and send it into the pyrolysis chamber inside the gas extraction device; S52, Immersion in slurry: While performing the substrate molding operation, open the second valve of the valve group to immerse the material in the molten pool into the pyrolysis chamber in the gas extraction device under negative pressure. S53, Pre-pyrolysis: Pre-pyrolyze the gaseous substances in the polymerization chamber, and let the pre-pyrolyzed gas enter the substrate polymerization chamber through the gas inlet valve; S54. Positive and negative pressure stirring: During pre-pyrolysis, the air pump is controlled to stir the polymerization chamber with positive and negative pressure fluctuations.

4. The environmentally friendly manufacturing process for low-emission acrylic sheets according to claim 3, characterized in that, The positive and negative pressure fluctuation stirring in step S54 specifically includes: S541: Maintain the internal pressure of the polymerization chamber at 1 / 3 of the external air pressure, and inject the pre-pyrolysis gas in the pyrolysis chamber into the polymerization chamber at a preset flow rate; S542: When the pressure inside the polymerization chamber reaches three times the external air pressure, open the air outlet and output the excess pre-pyrolysis gas into the pyrolysis chamber at a first preset flow rate; S543: When the gas pressure inside the polymerization chamber drops to 1 / 3 of the external gas pressure, close the gas outlet and repeat steps S541 and S542.

5. The environmentally friendly manufacturing process for low-emission acrylic sheets according to claim 1, characterized in that, In step S6, some of the material in the molten pool is precipitated into a sedimentation tank, and positive and negative pressure stirring is used to control the positive and negative pressure ratio to be 1:

3.

6. The environmentally friendly manufacturing process for low-emission acrylic sheets according to claim 1, characterized in that, In step S10, the gas in the polymerization chamber is drawn into the waste gas recovery device for treatment. Specifically, the waste gas is filtered and condensed in the waste gas recovery device, and then methacrylic acid and methanol are cracked and recovered to produce polymethyl methacrylate.

7. The environmentally friendly manufacturing process for low-emission acrylic sheets according to claim 1, characterized in that, The polymerization molding lamination in step S8 specifically includes: applying adhesive to the surfaces of two or more polymer plates, placing the polymer plates in a heated pressing tank while they are in contact with each other, heating them to 120°C at a heating rate of 4°C / min, and performing degassing and pressing operations while heating.

8. The environmentally friendly manufacturing process for low-emission acrylic sheets according to claim 7, characterized in that, The process of venting and pressing while heating specifically includes: venting excess gas from the substrate polymerization chamber at a preset speed, and slowly pressurizing at 0.2 MPa. When the pressure inside the polymerization chamber reaches 1 / 4 of the external air pressure, pressurization and venting are stopped to maintain a constant internal pressure in the polymerization chamber.

9. The environmentally friendly manufacturing process for low-emission acrylic sheets according to claim 1, wherein the waste gas recovery device is provided with a return pipeline, the return pipeline is connected to the substrate polymerization chamber, and the waste gas recovery device extracts polymethyl methacrylate from the waste gas according to a preset ratio and inputs it into the substrate polymerization chamber.

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