Catalytic oxidation and multi-stage devolatilization synergetic low-VOC polypropylene preparation device and method
By employing a synergistic approach of catalytic oxidation and multi-stage devolatilization, and utilizing hydrotalcite catalytic oxidation and a compound physicochemical adsorbent, the problem of VOC removal from polypropylene materials was solved, achieving efficient and stable VOC control and improved mechanical properties.
Patent Information
- Application Number
- CN202511277784.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-09
- Publication Date
- 2025-11-14
AI Technical Summary
In existing technologies, volatile organic compounds (VOCs) introduced during the production and processing of polypropylene materials are difficult to remove effectively. In particular, high VOC content can easily lead to adsorbent saturation, while low content and complex physicochemical properties of VOCs are difficult to remove completely. Furthermore, traditional devolatilization methods are inefficient and cannot meet the needs of industrial applications.
By employing a synergistic approach of catalytic oxidation and multi-stage devolatilization, and through segmented barrel design and multi-process control, combined with the catalytic oxidation function of hydrotalcite and compounded physicochemical adsorbents, targeted decomposition and depressurized devolatilization are achieved, forming a multi-mechanism synergistic effect to remove VOCs step by step.
It effectively reduces VOC content to below 10ppm, improves the mechanical properties of materials, solves the problems of adsorbent saturation and volatilization, improves volatilization efficiency and reduces costs, and is suitable for a variety of polymer material systems.
Smart Images
Figure CN120939889A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer material processing technology, and in particular to a low-VOC polypropylene preparation apparatus and method using synergistic catalytic oxidation and multi-stage devolatilization. Background Technology
[0002] Polypropylene (PP), as a low-density, easily processed, and mechanically excellent synthetic resin, has become one of the most widely used polymer materials globally, with applications in numerous industries such as automobiles, home appliances, and daily necessities. However, during the production and processing of polypropylene, volatile organic compounds (VOCs) are inevitably introduced into the material due to factors such as polymerization processes, types of processing aids, and processing methods. These VOCs include benzene compounds (such as toluene and xylene), aldehydes (such as formaldehyde), ketones (such as acetone), alkanes / olefins (such as n-hexane), oxygen-containing organic compounds, and halogenated hydrocarbons. These VOCs continue to evaporate during material use, especially in relatively enclosed environments such as automotive dashboards and interior trim, posing potential hazards to the human respiratory and nervous systems. Therefore, VOC control has become one of the core indicators of concern for industries such as automotive.
[0003] Currently, the removal of VOCs from polypropylene materials mainly relies on adsorption and devolatilization methods, but both methods have significant limitations. Adsorption methods achieve in-situ capture of VOCs by adding adsorbent materials to the material, and are divided into physical adsorption and chemical adsorption. Among them, physical adsorption has a fast adsorption rate, strong versatility, and low cost, but it is prone to adsorption saturation and desorption problems when dealing with high VOC content. If the problem is alleviated by increasing the amount of adsorbent, it will lead to a sharp decline in the mechanical properties of the material and an increase in density, which violates the requirements of lightweighting. Chemical adsorption achieves adsorption through chemical bonding, and the effect is relatively stable, but its versatility is extremely poor. One adsorbent can usually only remove 1-2 specific VOCs, and it also has the bottleneck of adsorption saturation. The devolatilization method allows VOCs to dynamically escape from the matrix by adjusting thermodynamic parameters or modifying extrusion equipment (such as setting up a multi-stage vacuum screw configuration). The core equipment is a screw extruder with an exhaust port and an external vacuum pump. However, this method has obvious drawbacks: First, it relies on a single devolatilization mechanism (such as vacuum decompression), making it difficult to build a multi-mechanism synergistic system. It has poor removal efficiency for complex VOC systems with coexisting polar / non-polar and high / low boiling points, limiting its applicability. Second, for VOC components that are well miscible with the polypropylene matrix, vacuum deboilation efficiency is extremely low. Third, when the VOC content is below 300 ppm, the removal capacity decreases significantly due to insufficient mass transfer driving force and adsorption threshold effect, making it impossible to achieve deep removal of residual VOCs.
[0004] Therefore, in order to address the problems in existing technologies where high VOC content easily leads to adsorbent saturation and low-content and complex VOC with complex physicochemical properties are difficult to completely remove, there is an urgent need to develop a new type of polypropylene material VOC removal device and method to achieve efficient and stable VOC control and meet the needs of industrial applications. Summary of the Invention
[0005] The purpose of this invention is to provide a low-VOC polypropylene preparation apparatus and method that combines catalytic oxidation and multi-stage devolatilization. The aim is to solve the industry bottleneck problem of easy adsorption saturation of high-content VOCs and difficulty in removing low-content and physicochemically complex VOC components by integrating a catalytic oxidation-multi-stage devolatilization device with a stepwise synergistic process, thereby achieving a reduction in VOC content and a significant improvement in mechanical properties of polypropylene materials.
[0006] On the one hand, the low-VOC polypropylene preparation apparatus for synergistic catalytic oxidation and multi-stage devolatilization provided by the present invention adopts the following technical solution:
[0007] A low-VOC polypropylene preparation apparatus combining catalytic oxidation and multi-stage devolatilization includes a motor, a barrel, a screw, and a die head. The barrel is provided with a first feed port, a first compression section, a second feed port, a melt-gas mixing section, a depressurization devolatilization section, a third feed port, a second compression section, and a melt metering section in sequence along the screw's spiral direction.
[0008] The decompression and devolatilization section includes an inert gas inlet and an exhaust port, and multiple sets of exhaust ports are provided.
[0009] By employing the aforementioned technical means, and through segmented barrel design and multi-process control technology, the dual goals of efficient devolatilization and material performance optimization are achieved. The barrel, along the screw's spiral direction, is sequentially configured with a first feed port, a first compression section, a second feed port, a melt-gas mixing section, a depressurization devolatilization section, a third feed port, a second compression section, and a melt metering section, forming a gradient processing flow. The first, second, and third feed ports allow for the gradient input of main materials, functional additives, and auxiliaries, effectively preventing compatibility issues caused by excessively high local concentrations. Depressurization devolatilization... The section includes an inert gas inlet and an exhaust port. By setting multiple sets of exhaust ports, the inert environment is used to suppress oxidation side reactions. At the same time, through the synergistic effect of screw shearing and depressurized devolatilization, free VOCs in the molten state are efficiently discharged, achieving efficient devolatilization. This invention can effectively avoid the two major problems of high residual VOC content after adsorption saturation of physicochemical adsorbents and the difficulty in removing VOCs with good miscibility with the matrix polymer through devolatilization. In addition, the application scope can be extended to other polymer material systems, providing a technical path that takes into account both energy efficiency and economy for the industrial production of low VOC materials.
[0010] Preferably, the decompression and devolatilization section is provided with an exhaust regulating block, and there are multiple sets of exhaust regulating blocks, with each set of exhaust regulating blocks located between two adjacent sets of exhaust ports.
[0011] By employing the above-mentioned technical means, the present invention is equipped with an exhaust regulating baffle. The exhaust regulating baffle effectively regulates the emission rate of inert gas and VOC by precisely controlling the opening of the exhaust port, which helps to maintain the internal pressure of the barrel and avoids melt flow disorder caused by pressure fluctuation. At the same time, the exhaust baffle can also guide the melt to form a more regular flow field, enhance the contact opportunity between the melt and the gas, and thus improve the efficiency of volatiles escaping from the melt.
[0012] Preferably, the first compression section includes a temperature zone one, a temperature zone two, and a temperature zone three;
[0013] The second compression section includes temperature zones four, five, and six; a vacuum device is provided between temperature zone six and the melt metering section.
[0014] Preferably, the length-to-diameter ratio of the screw is not less than 50:1.
[0015] On the other hand, the present invention also provides a method for preparing low-VOC polypropylene through synergistic catalytic oxidation and multi-stage devolatilization.
[0016] A method for preparing low-VOC polypropylene using a low-VOC polypropylene preparation apparatus with synergistic catalytic oxidation and multi-stage devolatilization as described above includes the following steps:
[0017] S1. Start the motor, the screw starts to rotate, take polypropylene resin and processing aids, mix them and put them into the first feed port, and melt and blend them in the first compression section to obtain the first mixture;
[0018] S2. Take hydrotalcite and put it into the second feed port, mix it with the first mixture obtained in step S1, and after catalytic decomposition of VOC in the melt gas mixing section, the second mixture is obtained.
[0019] S3. Inert gas is introduced into the inert gas inlet, so that the second mixture obtained in step S2 undergoes VOC removal in the depressurization devolatilization section under inert environment to obtain the third mixture;
[0020] S4. Take the compounded physicochemical adsorbent and put it into the third feed port to mix with the third mixture obtained in step S3. Melt and blend in the second compression section. After being vacuumed by the vacuum device, it is extruded from the die head through the melt metering section, water-cooled granulation and dried to obtain low VOC polypropylene material.
[0021] By employing the above-mentioned technical means, this invention utilizes a multi-mechanism synergistic mechanism of targeted decomposition, depressurized devolatilization, and physicochemical adsorption. It introduces hydrotalcite material with catalytic oxidation function into the second feed inlet, combining this with the device's multi-stage depressurized devolatilization structure and a physicochemical adsorption method to achieve complex physicochemical properties.
[0022] Effective removal of VOC components while avoiding adsorption saturation problems in high-VOC materials; utilizing the interlayer metal ions of hydrotalcite to target and catalyze the decomposition of some difficult-to-remove VOC components, transforming them into easily removable small molecules. For example, VOC components containing specific functional groups such as hydroxyl and carboxyl groups (e.g., aldehydes, ketones) can be converted into harmless substances such as carbon dioxide. This not only reduces the total VOC content but also significantly enhances the mass transfer driving force in the vacuum devolatilization stage. Simultaneously, the vacuum devolatilization equipment design creates a synergistic effect of "catalytic decomposition-gradient devolatilization." Residual low-content VOC components are removed by a compounded physicochemical adsorbent, thus forming a multi-level VOC deep removal method and material system to achieve the goal of producing low-VOC polypropylene materials. Adding the compounded physicochemical adsorbent at the third feed port allows for the adsorption of low-content VOCs. Compared with previous technologies, this invention does not require the addition of many additives, reducing the negative impact of adsorbents on the mechanical properties of materials; hydrotalcite loaded with different metal ions can catalytically decompose different VOC components, achieving efficient removal of multi-component VOCs; after devolatilization, a compound physicochemical adsorbent is introduced, since most of the VOCs have already been removed in the previous treatment process.
[0023] This method avoids the adsorption saturation problem that occurs with physicochemical adsorbents. At the same time, it greatly reduces the possibility that adsorbents with low hardness will be sheared and broken by the screw, thus affecting the adsorption effect and making them more efficient at absorbing VOCs.
[0024] Preferably, the temperature of the first compression section increases within the range of 70-180°C along the screw's spiral direction;
[0025] The temperatures of the second feed inlet, the melt-gas mixing section, the depressurization devolatilization section, and the third feed inlet are all 170-190℃;
[0026] The temperature of the second compression section increases within the range of 170-200℃ along the screw's spiral direction;
[0027] The temperature of the melt metering section is 170-210℃;
[0028] The temperature of the machine head is 170-200℃.
[0029] Preferably, the mass ratio of the polypropylene resin, processing aid, hydrotalcite and compound physicochemical adsorbent is (65-100):(0-25):(0-5):(0-5).
[0030] Preferably, the processing aid is at least one of filler, coupling agent, compatibilizer, antioxidant, and ultraviolet absorber;
[0031] The hydrotalcite is selected from, but is not limited to, at least one of magnesium aluminum hydrotalcite, zinc aluminum hydrotalcite, nickel aluminum hydrotalcite, and calcium aluminum hydrotalcite. The interlayer spacing of the hydrotalcite is 0.75-1.25 nm, and the specific surface area of the hydrotalcite is greater than 100 m². 2 / g.
[0032] Preferably, the compound physicochemical adsorbent includes a physical adsorbent and a chemical adsorbent, and the particle size of the compound physicochemical adsorbent is 500-10000 mesh;
[0033] The physical adsorbent is at least one of activated carbon, graphene, zeolite molecular sieve, and organic mesoporous silica.
[0034] The chemical adsorbent is at least one of HDV-536 resin, VOC degradation adsorbent, metal-organic framework, organic polymer TenaxTA, and odor absorber 602.
[0035] Preferably, the screw speed in step S1 is 150-700 rpm;
[0036] In step S4, the vacuum level extracted by the vacuum pumping device is -0.1 to 0.05 MPa.
[0037] In summary, the present invention has the following beneficial technical effects:
[0038] 1. This invention removes VOCs step by step through targeted decomposition, depressurized volatilization, and physicochemical adsorption, constructing a full-process VOC control system. Compared with single-stage treatment, it can reduce the VOC content in materials by more than 95%. It can effectively reduce the VOC content during processing and effectively avoid the adsorption saturation and desorption problems of adsorption methods and the difficulty of removing multiple VOCs in one step by volatilization methods.
[0039] 2. This invention utilizes the catalytic oxidation effect of metal ions in hydrotalcite on some VOCs, decomposing them into small molecules, and further performing vacuum volatilization to effectively reduce the VOC content. For the low-content residual VOCs that have not been removed, a compound physicochemical adsorbent is added for adsorption treatment, thereby achieving the ideal VOC removal effect. This method effectively avoids the two major problems of high residual VOCs after the physicochemical adsorbent is saturated and the difficulty in removing VOCs with good miscibility with the matrix polymer through volatilization, and can reduce the VOC content of the material to below 10 ppm.
[0040] 3. This invention removes VOC components from materials stepwise through melt reaction, vacuum devolatilization, and physicochemical adsorption. An inert gas is introduced and an exhaust port is provided to suppress oxidation side reactions in the inert environment. Simultaneously, the synergistic effect of screw shearing and vacuum devolatilization efficiently removes free VOCs in the molten state, achieving a devolatilization efficiency more than 90% higher than traditional methods. A synergistic functional strategy using a combination of physicochemical adsorbents is achieved, reducing raw material costs by approximately 70% compared to pure chemical modification methods while maintaining the material's mechanical properties. Furthermore, this method is continuous and solves the industrialization bottlenecks in traditional low-VOC polypropylene material preparation, such as frequent intermittent operations, high energy consumption, and poor batch stability. Attached Figure Description
[0041] Figure 1 This is a schematic diagram of the apparatus structure of the low-VOC polypropylene preparation device and method of the present invention, which combines catalytic oxidation and multi-stage devolatilization.
[0042] Figure 2 This is a schematic diagram of the decompression devolatilization section;
[0043] Figure 3 This is a schematic diagram of the apparatus for preparing polypropylene materials in Comparative Examples 1-3.
[0044] Explanation of reference numerals in the attached diagram: 1. Motor; 2. Barrel; 21. First feed port; 22. First compression section; 221. Temperature zone 1; 222. Temperature zone 2; 223. Temperature zone 3; 23. Second feed port; 24. Melt-gas mixing section; 25. Pressure reduction and devolatilization section; 251. Inert gas inlet; 252. Exhaust port; 253. Exhaust regulating block; 26. Third feed port; 27. Second compression section; 271. Temperature zone 4; 272. Temperature zone 5; 273. Temperature zone 6; 28. Melt metering section; 29. Vacuum device; 3. Screw; 4. Die head; 5. Second motor; 6. Second barrel; 61. Feed port; 62. Extrusion zone; 7. Second screw; 8. Second die head. Detailed Implementation
[0045] The following is in conjunction with the appendix Figure 1-3 The present invention will be further described in detail with reference to the embodiments.
[0046] Example
[0047] Example 1
[0048] Reference Figure 1 and Figure 2A low-VOC polypropylene preparation apparatus for synergistic catalytic oxidation and multi-stage devolatilization includes a motor 1, a barrel 2, a screw 3, and a die head 4. The motor 1 and the die head 4 are located at opposite ends of the barrel 2 along its length. The screw 3 is disposed inside the barrel 2, and the motor 1 drives the screw 3 to rotate. The barrel 2, along the screw 3's spiral direction, is sequentially provided with a first feed port 21, a first compression section 22, a second feed port 23, a melt-gas mixing section 24, a depressurization devolatilization section 25, a third feed port 26, a second compression section 27, and a melt metering section 28. The depressurization devolatilization section 25 includes an inert gas inlet 251 and an exhaust port 252, with multiple sets of exhaust ports 252. Among them, the first feeding port 21, the second feeding port 23 and the third feeding port 26 can realize the gradient input of main materials, functional additives and auxiliaries, effectively preventing compatibility problems caused by excessive local concentration; in the vacuum devolatilization section 25, the inert environment is used to suppress oxidation side reactions, and at the same time, through the synergistic effect of screw 3 shearing and vacuum devolatilization, the free VOCs in the molten state are efficiently discharged, realizing efficient devolatilization.
[0049] Reference Figure 1 and Figure 2 The inert gas inlet 251 of the depressurization and devolatilization section 25 has a downward opening direction, while the exhaust port 252 has an upward opening direction. There are 1-6 exhaust ports 252, the number of which can be set according to the VOC content. In this embodiment, 3 exhaust ports 252 are preferred. The depressurization and devolatilization section 25 is equipped with multiple sets of exhaust regulating blocks 253, evenly distributed along the length of the screw 3. In this embodiment, 3 sets of exhaust regulating blocks 253 are preferred. One set of exhaust regulating blocks 253 is located between the inert gas inlet 251 and its adjacent exhaust port 252, and the remaining sets of exhaust regulating blocks 253 are located between each pair of adjacent exhaust ports 252. By setting the exhaust port 252, the inert environment is used to suppress oxidation side reactions. At the same time, through the synergistic effect of shearing by the screw 3 and decompression devolatilization, free VOCs in the molten state are efficiently discharged, achieving efficient devolatilization. The exhaust regulating baffle 253 effectively regulates the emission rate of inert gas and VOC by precisely controlling the opening of the exhaust port 252, which helps to maintain the internal pressure of the barrel 2 and avoids melt flow turbulence caused by pressure fluctuations. At the same time, the exhaust regulating baffle 253 can also guide the melt to form a more regular flow field, enhance the contact opportunity between the melt and the gas, and thus improve the efficiency of volatiles escaping from the melt.
[0050] Reference Figure 1 and Figure 2The length-to-diameter ratio of the screw 3 is not less than 50:1, and in this embodiment, the length-to-diameter ratio of the screw 3 is preferably 70:1. The first compression section 22 includes temperature zone 1 221, temperature zone 222, and temperature zone 3 223; the second compression section 27 includes temperature zone 4 271, temperature zone 5 272, and temperature zone 6 273; a vacuum device 29 is provided between temperature zone 6 273 and the melt metering section 28. After the material passing through temperature zone 6 273 is evacuated by the vacuum device 29, it is extruded from the die head 4 through the melt metering section 28 to obtain low-VOC polypropylene material.
[0051] Example 2
[0052] A method for preparing low-VOC polypropylene using the above-mentioned synergistic catalytic oxidation and multi-stage devolatilization apparatus includes the following steps:
[0053] 1) Take 75 parts of copolymer polypropylene resin, 20.5 parts of processing aid, and 4 parts of a polymer with an interlayer spacing of 0.95 nm and a surface area of 200 m². 2 / g of hydrotalcite and 0.5 parts of compound physicochemical adsorbent are prepared for later use;
[0054] The hydrotalcite includes at least one of magnesium aluminum hydrotalcite, zinc aluminum hydrotalcite, nickel aluminum hydrotalcite, calcium aluminum hydrotalcite, or copper, cobalt, manganese, iron, chromium, and gallium ion-loaded hydrotalcite. In this embodiment, magnesium aluminum hydrotalcite is preferred.
[0055] The processing aids include 20 parts talc, 0.3 parts titanate coupling agent, and 0.2 parts antioxidant 1010;
[0056] The compound physicochemical adsorbent includes 0.2 parts of HDV-536 resin with a particle size of 500 mesh and 0.3 parts of zeolite molecular sieve with a particle size of 1000 mesh;
[0057] 2) Mix the copolymer polypropylene resin and processing aid prepared in step 1) in a mixer at 300 rpm for 10 min to obtain a premix.
[0058] 3) Start the motor, the screw starts to rotate at 300 rpm, set the temperature of zone 1 in the first compression section to 150℃, the temperature of zone 2 to 160℃ and the temperature of zone 3 to 170℃, put the premix obtained in step 2) into the first feed port, and melt and blend it in the first compression section to obtain the first mixture;
[0059] 4) Set the temperature of the second feed port, the melt gas mixing section, the depressurization devolatilization section and the third feed port to 180℃. Put the magnesium aluminum hydrotalcite prepared in step 1) into the second feed port and mix it with the first mixture in step 3). After the VOC is catalytically decomposed in the melt gas mixing section, the second mixture is obtained.
[0060] 5) Nitrogen gas is introduced into the inert gas inlet to allow the second mixture obtained in step 4) to undergo three-stage VOC removal in the depressurization devolatilization section under inert conditions and exhaust through multiple exhaust ports to obtain the third mixture;
[0061] 6) Set the temperature of zone four in the second compression section to 180℃, the temperature of zone five to 185℃, and the temperature of zone six to 185℃. Add the compound physicochemical adsorbent prepared in step 1) into the third feed port and mix it with the third mixture obtained in step 5). After melting and blending in the second compression section, vacuum the mixture using a vacuum device with a vacuum degree set to 0.04MPa, and then extrude it from the die head at 180℃ through the melt metering section at 185℃. After water cooling and granulation, dry it in a 120℃ forced-air drying oven for 2 hours to obtain low-VOC polypropylene material.
[0062] Example 3
[0063] A method for preparing low-VOC polypropylene using the above-mentioned synergistic catalytic oxidation and multi-stage devolatilization apparatus includes the following steps:
[0064] 1) Take 72 parts of copolymer polypropylene resin, 23.2 parts of processing aid, and 4 parts of a polymer with an interlayer spacing of 0.95 nm and a surface area of 200 m². 2 / g magnesium aluminum hydrotalcite and 0.8 parts of compound physicochemical adsorbent are prepared for later use;
[0065] The processing aids include 20 parts glass fiber, 3 parts maleic anhydride-grafted polypropylene FT-102 and 0.2 parts antioxidant 1010.
[0066] The compound physicochemical adsorbent includes 0.4 parts of HDV-536 resin with a particle size of 500 mesh and 0.4 parts of zeolite molecular sieve with a particle size of 1000 mesh;
[0067] 2) Mix the copolymer polypropylene resin and processing aid prepared in step 1) in a mixer at 300 rpm for 10 min to obtain a premix.
[0068] 3) Start the motor, the screw starts to rotate at 300 rpm, set the temperature of zone 1 in the first compression section to 160℃, the temperature of zone 2 to 170℃ and the temperature of zone 3 to 180℃, put the premix obtained in step 2) into the first feed port, and melt-blend it in the first compression section to obtain the first mixture;
[0069] 4) Set the temperature of the second feed port, the melt gas mixing section, the depressurization devolatilization section and the third feed port to 190℃. Put the magnesium aluminum hydrotalcite prepared in step 1) into the second feed port and mix it with the first mixture in step 3). After the VOC is catalytically decomposed in the melt gas mixing section, the second mixture is obtained.
[0070] 5) Nitrogen gas is introduced into the inert gas inlet to allow the second mixture obtained in step 4) to undergo three-stage VOC removal in the depressurization devolatilization section under inert conditions and exhaust through multiple exhaust ports to obtain the third mixture;
[0071] 6) Set the temperature of zone four in the second compression section to 190℃, the temperature of zone five to 195℃, and the temperature of zone six to 195℃. Add the compound physicochemical adsorbent prepared in step 1) into the third feed port and mix it with the third mixture obtained in step 5). After melting and blending in the second compression section, vacuum the mixture using a vacuum device with a vacuum degree set to 0.04MPa, and then extrude it from the die head at 190℃ through the melt metering section at 195℃. After water cooling and granulation, dry it in an 80℃ forced-air drying oven for 2 hours to obtain low-VOC polypropylene material.
[0072] Example 4
[0073] A method for preparing low-VOC polypropylene using the above-mentioned synergistic catalytic oxidation and multi-stage devolatilization apparatus includes the following steps:
[0074] 1) Take 100 parts of copolymer polypropylene resin for later use;
[0075] 2) Start the motor, the screw starts to rotate at 300 rpm, set the temperature of zone 1 in the first compression section to 155℃, the temperature of zone 2 to 165℃ and the temperature of zone 3 to 170℃, put the copolymer polypropylene resin prepared in step 1) into the first feed port, and melt-blend it in the first compression section to obtain the first mixture.
[0076] 3) Set the temperature of the second feed port, the melt-gas mixing section, the vacuum devolatilization section and the third feed port to 180℃. After the first mixture in step 2) undergoes catalytic decomposition of VOC in the melt-gas mixing section, the second mixture is obtained.
[0077] 4) Nitrogen gas is introduced into the inert gas inlet to allow the second mixture obtained in step 3) to undergo three-stage VOC removal in the depressurization devolatilization section under inert environment and exhaust through multiple exhaust ports to obtain the third mixture;
[0078] 5) Set the temperature of zone four in the second compression section to 185℃, the temperature of zone five to 185℃, and the temperature of zone six to 190℃. The third mixture obtained in step 4) is melted in the second compression section, then evacuated by a vacuum device with a vacuum degree of 0.04MPa, and then extruded from the die head at 185℃ in the melt metering section at 190℃. After water cooling granulation and drying in an 80℃ forced-air drying oven for 2 hours, low-VOC polypropylene material is obtained.
[0079] Comparative Example
[0080] Comparative Example 1
[0081] Reference Figure 3 A polypropylene preparation apparatus includes a second motor 5, a second barrel 6, a second screw 7, and a second die head 8. The second motor 5 and the second die head 8 are located at opposite ends of the length of the second barrel 6. The second screw 7 is disposed inside the second barrel 6, and the second motor 5 drives the second screw 7 to rotate. The second barrel 6 has a feeding port 61 and an extrusion zone 62 arranged sequentially along the screw 7's spiral direction. Multiple sets of extrusion zones 62 are provided; in this comparative example, eight sets of extrusion zones 62 are preferably provided. The length-to-diameter ratio of the screw is 45:1.
[0082] The method for preparing polypropylene using the aforementioned polypropylene preparation apparatus specifically includes the following steps:
[0083] 1) Take 73 parts of copolymer polypropylene resin, 20.5 parts of processing aid, and 5 parts of a polymer with an interlayer spacing of 0.95 nm and a surface area of 200 m². 2 / g magnesium aluminum hydrotalcite and 1.5 parts of compound physicochemical adsorbent are prepared for later use;
[0084] The processing aids include 20 parts talc, 0.3 parts titanate coupling agent, and 0.2 parts antioxidant 1010;
[0085] The compound physicochemical adsorbent includes 0.5 parts of HDV-536 resin with a particle size of 500 mesh and 1 part of zeolite molecular sieve with a particle size of 1000 mesh.
[0086] 2) Mix the copolymer polypropylene resin, processing aid, magnesium aluminum hydrotalcite and compound physicochemical adsorbent prepared in step 1) in a mixer at a speed of 300 rpm for 10 min to obtain a premix.
[0087] 3) Start the second motor, and the second screw starts to rotate at a speed of 300 rpm. The temperatures of the eight extrusion zones along the direction of the second screw's rotation are set to 150℃, 160℃, 170℃, 175℃, 180℃, 185℃, 190℃, and 185℃, respectively. The premixed material obtained in step 2) is fed into the feeding port to prepare polypropylene material. After preparation, it is extruded from the second die head at 185℃, water-cooled and granulated, and dried in a 120℃ forced-air drying oven for 2 hours to obtain polypropylene material.
[0088] Comparative Example 2
[0089] Using the polypropylene preparation apparatus in Comparative Example 1, the method for preparing polypropylene specifically includes the following steps:
[0090] 1) Take 70 parts of copolymer polypropylene resin, 23.7 parts of processing aid, and 5 parts of a polymer with an interlayer spacing of 0.95 nm and a surface area of 200 m². 2 / g magnesium aluminum hydrotalcite and 1.3 parts of compound physicochemical adsorbent are prepared for later use;
[0091] The processing aids include 20 parts glass fiber, 3.5 parts maleic anhydride-grafted polypropylene FT-102 and 0.2 parts antioxidant 1010.
[0092] The compound physicochemical adsorbent includes 0.5 parts of HDV-536 resin with a particle size of 500 mesh and 0.8 parts of zeolite molecular sieve with a particle size of 1000 mesh;
[0093] 2) Mix the copolymer polypropylene resin, processing aid, magnesium aluminum hydrotalcite and compound physicochemical adsorbent prepared in step 1) in a mixer at a speed of 300 rpm for 10 min to obtain a premix.
[0094] 3) Start the second motor, and the second screw starts to rotate at a speed of 300 rpm. The temperatures of the eight extrusion zones along the screw's rotation direction are set to 160℃, 170℃, 180℃, 185℃, 190℃, 195℃, 200℃, and 195℃, respectively. The premixed material obtained in step 2) is fed into the feed port to prepare polypropylene material. After preparation, it is extruded from the second die head at 195℃, water-cooled and granulated, and dried in an 80℃ forced-air drying oven for 2 hours to obtain polypropylene material.
[0095] Comparative Example 3
[0096] Using the polypropylene preparation apparatus in Comparative Example 1, the method for preparing polypropylene specifically includes the following steps:
[0097] 1) Take 100 parts of copolymer polypropylene resin for later use;
[0098] 2) Start the second motor, and the second screw starts to rotate at a speed of 300 rpm. The temperatures of the eight extrusion zones along the screw's rotation direction are set to 155℃, 165℃, 170℃, 175℃, 180℃, 180℃, 185℃, and 180℃, respectively. The copolymer polypropylene resin prepared in step 1) is fed into the feed port to prepare the polypropylene material. After preparation, it is extruded from the second die head at 180℃, water-cooled and granulated, and dried in an 80℃ forced-air drying oven for 2 hours to obtain the polypropylene material.
[0099] Test case
[0100] Test Example 1
[0101] VOC tests were conducted on polypropylene materials prepared in Examples 2-4 and Comparative Examples 1-3 respectively. The test standard was in accordance with ISO 12219-2:2012 "Screening method for determination of volatile organic compounds in automotive interior parts and materials - bag method". The results are shown in Table 1.
[0102] Table 1 VOC content of polypropylene materials (unit: μg / m³) 3 )
[0103]
[0104] According to the test results in Table 1, for the preparation method of adding inorganic filler (talc), in combination with Example 2 and Comparative Example 1, the low VOC polypropylene preparation device and method of catalytic oxidation and multi-stage devolatilization synergy of the present invention in Example 2 improves the VOC removal effect by 70-80% compared with the polypropylene material preparation device and preparation method of the comparative example.
[0105] Regarding the preparation method of adding glass fiber, in combination with Example 3 and Comparative Example 2, the low VOC polypropylene preparation device and method of Example 3 of the present invention, which combines catalytic oxidation and multi-stage devolatilization, improves the VOC removal effect by more than 80% compared with the polypropylene material preparation device and method of the comparative example.
[0106] Based on the test results of Example 4 and Comparative Example 3, it can be seen that the low-VOC polypropylene preparation apparatus and method of the present invention, which combines catalytic oxidation and multi-stage devolatilization, has a better VOC removal effect on pure polypropylene than the polypropylene material preparation apparatus and method of the comparative example.
[0107] Comparing the results of Examples 2-4 and Comparative Examples 1-3, it can be seen that even without adding any additional additives, using only the equipment and method for preparing polypropylene materials to prepare pure materials can still reduce VOC content, but the effect is not significant compared to the synergistic effect of adding additional additives.
[0108] Test Example 2
[0109] The polypropylene materials prepared in Examples 2-4 and Comparative Examples 1-3 were subjected to mechanical and thermal property analysis. Tensile strength was tested according to ISO 527-1-2019 "Plastics – Determination of tensile properties"; flexural strength and flexural modulus were tested according to ISO 178-2010 "Plastics – Determination of flexural properties"; notched impact strength of cantilever beams was tested according to ISO 180-2023 "Plastics – Determination of cantilever beam impact strength"; and heat distortion temperature under load was tested according to ISO 75-1-2013 "Plastics – Determination of temperature of deflection under load". The test results are shown in Table 2.
[0110] Table 2 Properties of Polypropylene Materials
[0111]
[0112] According to the test results in Table 2, compared with Comparative Example 3, the mechanical and thermal properties of the material prepared in the present invention are slightly better than those of the material prepared in the comparative example. This is because when there is a lot of residual VOC in the material, structural defects will be generated inside the material, the interfacial bonding force will be weakened, and thus the mechanical properties will be negatively affected. The device for removing VOC from polypropylene material by catalytic oxidation-multi-stage devolatilization further reduces the VOC content during the preparation process.
[0113] By comparing Examples 2-3 with Comparative Examples 1-2, it can be found that the materials prepared by adding additional additives (processing aids, hydrotalcite and compounded physicochemical adsorbents) during the preparation of polypropylene materials, combined with the catalytic oxidation-multi-stage devolatilization device of the present invention for removing VOCs from polypropylene materials, have good mechanical properties and thermal stability, and are of high quality.
[0114] In summary, the low-VOC polypropylene preparation apparatus and method of the present invention, which combines catalytic oxidation and multi-stage devolatilization, can simultaneously achieve effective reduction of VOC content and improvement of mechanical properties and thermal stability of the material during the material preparation process, and has broad application prospects.
[0115] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.
Claims
1. A low-VOC polypropylene preparation apparatus for synergistic catalytic oxidation and multi-stage devolatilization, comprising a motor (1), a barrel (2), a screw (3), and a die head (4), characterized in that, The barrel (2) is provided with a first feeding port (21), a first compression section (22), a second feeding port (23), a melt-gas mixing section (24), a pressure reduction and devolatilization section (25), a third feeding port (26), a second compression section (27), and a melt metering section (28) in sequence along the screw (3) spiral direction. The decompression and devolatilization section (25) includes an inert gas inlet (251) and an exhaust port (252), and the exhaust port (252) is provided in multiple sets.
2. The low-VOC polypropylene preparation apparatus according to claim 1, characterized in that, The decompression and de-volume section (25) is provided with an exhaust regulating block (253). There are multiple sets of exhaust regulating blocks (253), and each set of exhaust regulating blocks (253) is located between two adjacent sets of exhaust ports (252).
3. The low-VOC polypropylene preparation apparatus based on the synergistic effect of catalytic oxidation and multi-stage devolatilization according to claim 1, characterized in that, The first compression section (22) includes temperature zone 1 (221), temperature zone 2 (222) and temperature zone 3 (223); The second compression section (27) includes temperature zone four (271), temperature zone five (272) and temperature zone six (273); a vacuum device (29) is provided between temperature zone six (273) and melt metering section (28).
4. The low-VOC polypropylene preparation apparatus according to claim 1, characterized in that, The length-to-diameter ratio of the screw (3) is not less than 50:
1.
5. A method for preparing a low-VOC polypropylene preparation apparatus according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Start the motor (1), the screw (3) starts to rotate, take polypropylene resin and processing aids, mix them and put them into the first feeding port (21), and melt and blend them through the first compression section (22) to obtain the first mixture; S2. Take water talc and put it into the second feed port (23), mix it with the first mixture obtained from step S1, and after the VOC is catalytically decomposed in the melt gas mixing section (24), the second mixture is obtained. S3. Inert gas is introduced into the inert gas inlet (251) so that the second mixture obtained in step S2 is subjected to VOC removal in the depressurization devolatilization section (25) under inert environment to obtain the third mixture; S4. Take the compounded physicochemical adsorbent and put it into the third feed port (26) and mix it with the third mixture obtained in step S3. Melt and blend it in the second compression section (27). After being vacuumed by the vacuum device (29), it is extruded from the die head (4) through the melt metering section (28), water-cooled granulation and drying to obtain low VOC polypropylene material.
6. The method for preparing low-VOC polypropylene by synergistic catalytic oxidation and multi-stage devolatilization according to claim 5, characterized in that, The temperature of the first compression section (22) increases within the range of 70-180℃ along the screw (3) spiral direction; The temperatures of the second feed inlet (23), the melt-gas mixing section (24), the depressurization and devolatilization section (25) and the third feed inlet are all 170-190℃; The temperature of the second compression section (27) increases within the range of 170-200℃ along the screw (3) spiral direction; The temperature of the melt metering section (28) is 170-210℃; The temperature of the machine head (4) is 170-200℃.
7. The method for preparing low-VOC polypropylene by synergistic catalytic oxidation and multi-stage devolatilization according to claim 5, characterized in that, The mass ratio of the polypropylene resin, processing aid, hydrotalcite and compound physicochemical adsorbent is (65-100):(0-25):(0-5):(0-5).
8. The method for preparing low-VOC polypropylene by synergistic catalytic oxidation and multi-stage devolatilization according to claim 5, characterized in that, The processing aid is at least one of the following: filler, coupling agent, compatibilizer, antioxidant, and ultraviolet absorber; The hydrotalcite is selected from, but is not limited to, at least one of magnesium aluminum hydrotalcite, zinc aluminum hydrotalcite, nickel aluminum hydrotalcite, and calcium aluminum hydrotalcite. The interlayer spacing of the hydrotalcite is 0.75-1.25 nm, and the specific surface area of the hydrotalcite is greater than 100 m². 2 / g.
9. The method for preparing low-VOC polypropylene by synergistic catalytic oxidation and multi-stage devolatilization according to claim 5, characterized in that, The compound physicochemical adsorbent includes physical adsorbents and chemical adsorbents, and the particle size of the compound physicochemical adsorbent is 500-10000 mesh. The physical adsorbent is at least one of activated carbon, graphene, zeolite molecular sieve, and organic mesoporous silica. The chemical adsorbent is at least one of HDV-536 resin, VOC degradation adsorbent, metal-organic framework, organic polymer TenaxTA, and odor absorber 602.
10. The method for preparing low-VOC polypropylene by synergistic catalytic oxidation and multi-stage devolatilization according to claim 5, characterized in that, The rotational speed of the screw (3) in step S1 is 150-700 rpm; In step S4, the vacuum level extracted by the vacuum pumping device (29) is -0.1 to 0.05 MPa.