On-line modified extrusion double-granulation device and PP on-line modified extrusion double-granulation device

Abstract

The invention provides an on-line modified extrusion double-granulation device, which comprises: a main extrusion line, which comprises a first extruder, a melt pump, a filter device and a first granulation device, which are connected in sequence; the modified extrusion line comprises a second extruder, at least one functional material feeding scale and a second pelletizing device, the second extruder is connected with the second pelletizing device, the functional material feeding scale is connected with the second extruder, the second extruder is a double-screw extruder, and the functional material feeding scale is connected with the second pelletizing device. At least one meshing block screw section or tooth-shaped disc screw section is arranged on the screw, and the position of the meshing block screw section or the tooth-shaped disc screw section corresponds to the position of the functional material feeding scale; and the shunting pipeline is used for shunting part of the melt in the main machine outgoing line to the modified extrusion line before the melt in the main extrusion line enters the first pelletizing device.

Description

Technical Field

[0001] The present invention generally relates to the field of extruder equipment, and in particular to a modified extrusion equipment and process. Background Art

[0002] Physical modifications of polymer materials include filling modification, blending modification, and reinforcement modification. Polymer materials are polymers, and many polymers have extremely high molecular weights. This results in their physical properties being characterized by high viscosity, and even solidity at room temperature and pressure. In response to human needs, the development of polymer materials tends towards composite modification, allowing their superior properties to be demonstrated and missing properties to be supplemented. Taking polypropylene (PP) as an example, it is a semi-crystalline thermoplastic polymer made from propylene monomers through polyaddition reactions. Adding organic or inorganic additives to the PP matrix during the mixing and kneading process results in PP composite materials with excellent performance, which mainly include filling modification, blending modification, and reinforcement modification.

[0003] (1) Filling modification

[0004] Filling modification is the addition of fillers such as silicate, silica, cellulose, glass fiber, calcium carbonate, clay, talc and mica to PP, aiming to improve the heat resistance of PP, reduce costs, increase rigidity, reduce molding shrinkage and other properties. However, filling modification will lead to a decrease in the impact strength and elongation of PP. Different fillers added in filling modification have different characteristics and functions. For example, glass fiber is an inorganic non-metallic whisker with excellent performance. It is low in price, has good insulation, strong heat resistance, good corrosion resistance, and high mechanical strength. It is widely used. The performance of PP modified by glass fiber filling is significantly improved. However, the mechanical properties of the material can only be significantly improved when the glass fiber addition reaches about 30%. If the addition amount is too large, part of the glass fiber will not be fully impregnated, which will deteriorate the bonding performance of the polymer matrix and the glass fiber interface, resulting in a decrease in the mechanical strength of the composite material. As the amount of glass fiber added increases, the flowability of the composite material decreases, resulting in poor PP molding processability. Energy difficulties; calcium carbonate can reduce product costs, improve product performance, and increase its stiffness, hardness, heat resistance, and dimensional stability; clay, also known as kaolin, is a plastic filler with excellent electrical insulation and can be used to manufacture various wire sheaths. It can also be used as a crystallization nucleating agent to improve the uniformity of material crystallization and enhance product transparency. It also has a certain flame retardant effect and can be used as an auxiliary flame retardant modification; talc powder, as a filler, can improve product stiffness, hardness, flame retardant properties, electrical insulation properties, dimensional stability, and has a lubricating effect; mica can increase PP modulus and heat resistance, reduce creep, prevent product warping, and reduce molding shrinkage.

[0005] (2) Blending modification

[0006] Blending modification refers to the process of mixing two or more polymer materials and additives at a certain temperature to modify their properties. For example, to improve low-temperature impact resistance, PP can be blended with EPDM (ethylene propylene diene monomer), POE (polyolefin elastomer), EVA (ethylene-vinyl acetate copolymer), and SBS (styrene-butadiene block copolymer). However, the compatibility between the polymers must be carefully considered during blending modification. The desired modification effect can only be achieved when a heterogeneous system, which is not completely compatible but also uniformly dispersed, is formed. The blending modification process is easy to control, has a short production cycle, and is low-cost. It can improve various properties of PP, including colorability, processability, antistatic properties, and impact resistance. Polymer blending can combine the strengths of each component and compensate for any deficiencies, significantly improving the overall performance of the blend. However, the low-temperature resistance and aging resistance of blended PP remain less than ideal. During blending modification, shear force may cause a part of the macromolecular chains to be cut to form free radicals and form grafted or block copolymers. These new copolymers can also effectively increase the compatibilization of PP.

[0007] (3) Enhancement modification

[0008] Adding fibrous materials to plastics can significantly increase their strength, hence the term "reinforcement modification." Materials with a high diameter-to-thickness ratio can significantly increase their flexural modulus (rigidity), also known as "reinforcement modification."

[0009] The reinforcing materials used in the modification of PP (polypropylene) are primarily glass fiber and its products, in addition to carbon fiber, organic fiber, boron fiber, whiskers, etc. In glass fiber-reinforced PP, alkali-free glass fiber and medium-alkali glass fiber are the most commonly used, with alkali-free glass fiber being the most widely used. The glass fiber diameter is controlled within the range of 6 to 15 μm, and the glass fiber length must be maintained between 0.25 and 0.76 mm. This ensures both product performance and good dispersion of the glass fiber. It is generally believed that the modification effect is only achieved when the glass fiber length in the product is greater than 0.2 mm. The optimal glass fiber content (mass fraction) is 10% to 30%, with performance deteriorating when it exceeds 40%. Furthermore, the addition of an organosilane coupling agent can form a good interface between the glass fiber and PP, improving the composite system's flexural modulus, hardness, load deflection temperature, and particularly dimensional stability.

[0010] Because glass fiber reinforced PP can improve mechanical strength and heat resistance, and glass fiber reinforced PP has good water vapor resistance, chemical corrosion resistance and creep resistance, it can be used as engineering plastics in many occasions, such as fan blades, heater grilles, impeller pumps, lampshades, electric furnaces and heater housings, etc.

[0011] While the production quantity of polypropylene is growing rapidly, its performance is also constantly being innovated, which makes the breadth and depth of its application constantly changing. In recent years, some new varieties of polypropylene with more unique properties have come out, such as transparent polypropylene and high melt strength polypropylene, either by improving the polymerization reaction or taking measures during granulation after polymerization.

[0012] Regarding the implementation method of the above-mentioned physical modification, generally, the pelletized polymer material is melted in a screw extruder, and a modifier is added to perform modification treatment, followed by granulation to form modified particles.

[0013] The contents of the background technology section are merely the technologies known to the applicant and do not necessarily represent the existing technologies in this field. Summary of the Invention

[0014] In view of one or more problems existing in the prior art, the present invention provides an online modified extrusion double granulation device, comprising:

[0015] A main extrusion line comprises a first extruder, a melt pump, a filter device and a first pelletizing device, wherein the first extruder, the melt pump, the filter device and the first pelletizing device are connected in sequence;

[0016] The modified extrusion line includes a second extruder, at least one functional material feed scale, and a second pelletizing device, wherein the second extruder is connected to the second pelletizing device, and the functional material feed scale is connected to the second extruder. The second extruder is a twin-screw extruder having at least one meshing block screw segment or toothed disk screw segment on its screw, and the position of the meshing block screw segment or toothed disk screw segment corresponds to the position of the functional material feed scale;

[0017] The diversion pipeline is used to divert part of the melt in the main extrusion line to the modified extrusion line before the melt in the main extrusion line enters the first pelletizing device.

[0018] Furthermore, as a preferred solution, the first pelletizing device is an underwater pelletizing device.

[0019] As another preferred embodiment, the second pelletizing device is a strand pelletizing device.

[0020] Furthermore, the main extrusion line further includes a drain valve, which is arranged between the melt pump and the filtering device.

[0021] Furthermore, the first extruder includes a pressure building section.

[0022] Furthermore, the functional material feeding machine is connected to the second extruder in a side feeding manner.

[0023] Furthermore, the modified extrusion line is connected to two or more functional material feeding scales.

[0024] Furthermore, the diversion pipeline includes a melt pipe, a buffer hopper, and a gear pump, which are connected in sequence; wherein, a control valve and a drain valve are provided on the melt pipe, and the gear pump is arranged between the buffer hopper and the second extruder.

[0025] Furthermore, the melt pipe and buffer hopper are both provided with jacket insulation devices.

[0026] This application also provides a PP online modified extrusion twin granulation device, using the above device, the first extruder is a twin-screw extruder, and the upstream section of the screw is a meshing block screw for completing the grinding and melting of the PP powder. Preferably, the length of the meshing block screw is 5D.

[0027] Preferably, the functional material feeding scale is configured such that a polymer material feeding scale and an inorganic filler feeding scale are sequentially connected to the second extruder along the direction of melt travel.

[0028] Furthermore, the length of the meshing screw on the second extruder corresponding to the polymer material feeding scale is 4D; the length of the meshing screw on the second extruder corresponding to the inorganic filler feeding scale is 6D.

[0029] Furthermore, the second extruder is also connected to an additive feeding scale.

[0030] Furthermore, the length of the intermeshing block screw on the second extruder corresponding to the additive feeding scale is 2D.

[0031] Furthermore, the first extruder is also provided with a melt devolatilization section.

[0032] The present application uses two extrusion lines working simultaneously to complete the physical modification of polymer materials, ensuring the needs of multiple modifications during the extrusion granulation process, that is, to simultaneously produce polymer material particles and polymer material particles after the required physical modification. It effectively saves the process flow, reduces production costs, and ensures the quality of the polymer material particles and modified particles prepared at the same time. The present application scheme is particularly effective in improving the efficiency of online modification of PP materials. PP material is powdery at room temperature and pressure. In addition to the large demand for its pure PP material, its various physically modified products are also in great demand. Based on the online modified extrusion double granulation device, the present application designs a precise twin-screw combination structure for the main extrusion line and the modified extrusion line of the PP material, which significantly improves its efficiency in actual production. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0034] Figure 1 2 is a schematic structural diagram of an online modified extrusion double granulation device according to one embodiment of the present invention;

[0035] Figure 2 2 is a schematic structural diagram of a PP online modified extrusion double granulation device according to one embodiment of the present invention;

[0036] Among them, 1: main extrusion line, 2: modified extrusion line, 3: diversion pipeline, 11: first extruder, 12: melt pump, 13: filtering device, 14: first pelletizing device, 111: melt plasticizing section, 10: meshing block screw, 112: melt devolatilization section, 113: pressure building section, 15: drain valve, 21: second extruder, 22: second pelletizing device, 201: first functional material feeding scale ( Figure 1 ) or polymer material feeding ( Figure 2 ), 202: Second function material feeding scale ( Figure 1 ) or inorganic filler feed ( Figure 2 ), 203: additive feeding scale, 211, 212, 213: meshing block screw section, 31: melt pipe, 32: buffer hopper, 33: gear pump, 34: control valve, 35: drain valve. DETAILED DESCRIPTION

[0037] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present application. Therefore, the drawings and description are to be regarded as illustrative in nature and not restrictive.

[0038] In the description of this application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this application and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting this application. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly indicate the number of the technical features indicated. Therefore, features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of this application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0039] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections, or interconnected connections; direct connections or indirect connections through an intermediary; and internal connections between two components or interactions between two components. Those skilled in the art will understand the specific meanings of these terms in this application based on specific circumstances.

[0040] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact via another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or diagonally above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly above or diagonally above the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0041] The disclosure below provides many different embodiments or examples for realizing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art will appreciate the application of other processes and / or the use of other materials.

[0042] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application and are not used to limit the present application.

[0043] Example 1:

[0044] like Figure 1 As shown, the first embodiment of the present invention provides an online modified extrusion dual granulation device, comprising: a main extrusion line 1, a modified extrusion line 2, and a diversion pipeline 3. The main extrusion line 1 produces particles of the initial polymer material through extrusion, melting, and granulation. The diversion pipeline 3 diverts a portion of the melt from the main extrusion line 1 to the modified extrusion line 2 for modification. The modified extrusion line 2 also utilizes an extruder, where filler is added and mixed, extruded, and granulated to ultimately produce particles of the modified polymer composite material.

[0045] The specific structures of the main extrusion line 1, the modified extrusion line 2 and the diversion pipeline 3 are described in detail below.

[0046] Main extrusion line 1

[0047] The main extrusion line includes a first extruder 11, a melt pump 12, a filter device 13 and a first pelletizing device 14, and the first extruder 11, the melt pump 12, the filter device 13 and the first pelletizing device 14 are connected in sequence. The first pelletizing device 14 is an underwater pelletizing device. The first extruder 11 adopts a twin-screw extruder. Generally, the first extruder 11 only needs to meet the necessary conditions for online modification under the condition of having a pressure building section 113. However, for different materials, other extrusion sections can be added to the first extruder. For example, for the online modification of PP materials that need to be protected in this application, the first extruder 11 also needs to set a melt plasticizing section 111 and a melt devolatilization section 112 at the most upstream. The melt-plasticizing section 111 utilizes a combination of a transmission element and an intermeshing screw. The transmission element continuously supplies PP powder, while the intermeshing screw provides shear heat and melts it. The melt-devolatilization section 112 utilizes a combination of a transmission element and a toothed disc screw. The toothed disc shears the molten PP into pieces, increasing its specific surface area and facilitating devolatilization. The pressure-building section 113 utilizes a conventional twin-screw extruder, which acts as a conveyor, driving the material downstream to the melt pump 12 while simultaneously increasing the material pressure, typically to 5-10 MPa. Under the action of the pressure-building section 112, the molten material moves from the mixing and dispersing section 111 to the pressure-building section 113 and then flows into the melt pump 12, which rapidly increases the material pressure to 15-30 MPa. The filtration device 13 generally utilizes a filter screen. The mesh size of the filter screen can be selected based on the molecular size of the material after cross-linking or oxidation. The selection of the mesh size is a routine method used by those skilled in the art. Filter 13 removes unqualified materials such as cross-linked materials and yellowing materials (typically caused by oxidation), thereby improving product purity. After passing through the high-resistance filter 13, the pressure of the material rapidly decreases, typically to 5-10 MPa. The relatively clean polymer material after filtration passes through underwater pelletizing device 14 (the first pelletizing device), where it is solidified and pelletized to produce polymer particles.

[0048] As a preferred embodiment, a drain valve 15 is provided between the melt pump 12 and the filtering device 13 in this embodiment to detect and discharge waste materials such as aged yellow materials in the equipment.

[0049] Modified extrusion line 2

[0050] The modified extrusion line includes a second extruder 21, a second pelletizing device 22 and at least one functional material feeding scale. Figure 1As shown, this embodiment takes two types of fillers as an example, a first functional material feed scale 201 and a second functional material feed scale 202. The diversion pipeline 3 inputs part of the melt of the polymer material melt of the main extrusion line to the second extruder 21. Through the research of this application, it was found that the diversion amount is too large and difficult to control. The diverted partial melt generally accounts for less than 30% of the melt of the main extrusion line, which can ensure the balanced operation of the two extrusion lines. When the diverted partial melt accounts for 8-13% of the melt of the main extrusion line, it is more beneficial to the balance of the two extrusion lines, with low control difficulty and higher stability. The second extruder 21 is connected to the second pelletizing device 22, and the first functional material feed scale 201 and the second functional material feed scale 202 are respectively connected to the second extruder 21. The second extruder 21 is a twin-screw extruder, and the positions corresponding to the first functional material feed scale 201 and the second functional material feed scale 202 on the twin screw of the second extruder are provided with meshing block screws, that is, meshing block screw segments 211 and 212 are formed on the twin screw. The purpose of the meshing block screw segments 211 and 212 is to achieve sufficient dispersion and mixing of the polymer melt and the added functional fillers. Those skilled in the art can determine the length of the meshing block screw segments 211 and 212 according to the composite material to be dispersed. The polymer melt is mixed by the meshing block screw segments 211 and 212 and is fed into the second pelletizing device 22 under the drive of the twin screw. The present application can also use a toothed disc screw instead of the meshing block screw, and then form the toothed disc screw segments 211 and 212 on the twin screw. Most of the functional materials are inorganic materials such as fibers and particles, and some are large molecular organic materials. The shapes of these fillers are very different from those of the molten polymer materials, making them difficult to mix and also making the filling process difficult. The existing mixing process of adding these fillers is mainly completed in a mixing kettle with stirring or shearing functions, which is difficult to complete directly on the extrusion line. In order to overcome this difficulty, the present application decomposes the functional materials into multiple functional material feeding scales according to the filler morphology and function, and cooperates with multiple meshing block screw segments, while adopting a side feeding method. The second pelletizing device 22 is a strand pelletizing device, which is a commonly used pelletizing device in the art. The composite material modified by the second extruder 21 is extruded into the strand pelletizing device 22 for drawing, cooling, and pelletizing to obtain composite material particles.

[0051] Diverter line 3

[0052] The diversion pipeline 3 is used to divert part of the melt in the main extrusion line 1 to the modified extrusion line 2 before the melt in the main extrusion line 1 enters the first pelletizing device 14. The diversion pipeline 3 includes a melt pipe 31, a buffer hopper 32, and a gear pump 33, and the melt pipe 31, the buffer hopper 32, and the gear pump 33 are connected in sequence; wherein, the melt pipe is provided with a control valve 34 and a drain valve 35. The gear pump 33 is arranged between the buffer hopper 32 and the second extruder 21. One end (feed end) of the melt pipe 31 is arranged upstream of the first pelletizing device 14 and connected to the first pelletizing device 14. At this time, the pressure of the melt on the main extrusion line is the lowest, which is more conducive to controlling the balanced operation of the main extrusion line 1 and the modified extrusion line 2. In this embodiment, the feed end of the melt pipe 31 is arranged between the filter device 13 and the first pelletizing device 14. The melt pipe 31 sends the diverted melt into the buffer hopper 32, which is then pumped into the second extruder 21 after being pressurized by the gear pump 33. The melt pipe 31 and the buffer hopper 32 are both equipped with jacket insulation devices to ensure the fluidity of the melt. Before opening the control valve 34, the air in the modified extrusion line 2 is first discharged from the modified extrusion line 2 with nitrogen or other inert gases. Before the second extruder 21 of the modified extrusion line 2, the control valve 34 is opened, and the melt in the main extrusion line 1 enters the melt pipe 31 and is tested by the drain valve 35. If the melt does not meet the process requirements, the grounding end of the drain valve 35 is opened to discharge it. When the detected melt meets the process requirements, the grounding end is closed and it enters the buffer hopper 32. The material storage capacity in the buffer hopper 32 can be controlled by the control valve 34, and can be adjusted according to the processing speed of the modified extrusion line 2.

[0053] Example 2:

[0054] like Figure 2 As shown, this embodiment shows an online modified extrusion double granulation device for PP. Polypropylene (Polypropylene, referred to as PP) is solid at room temperature and pressure. This embodiment can achieve online physical modification of solid PP. This embodiment has made precise improvements on the basis of the device of Example 1. The main improvement is that the first extruder 11 adopts a twin-screw extruder, and the upstream section of the screw is an intermeshing block screw 10, which is used to complete the grinding and melting of PP powder. The length of the intermeshing block screw 10 is 5D, and the unit of D is mm. The actual length of D is related to the model of the extruder. For example: if the model of the extruder is GP52, then D = 52mm, and the following "D" is explained in the same way. As Figure 1As shown, this embodiment is an online modified extrusion double granulation device for PP materials, wherein the first extruder 11 is configured to include a melt plasticizing section 111 located upstream, a melt devolatilization section 112 located midstream, and a pressure building section 113 located downstream. The melt plasticizing section 111 uses a combination of a transmission element and an intermeshing block screw 10. The transmission element continuously provides PP powder, and the intermeshing block screw provides shear heat and melts it. The melt devolatilization section 112 uses a combination of a transmission element and a toothed disk screw. The toothed disk is used to shear the molten PP into pieces, thereby increasing its specific surface area and being more conducive to devolatilization. Figure 2 As shown, the functional material feeding scale is set up in such a way that a polymer material feeding scale 201, an inorganic filler feeding scale 202 and an additive feeding scale 203 are sequentially connected to the second extruder along the direction of travel of the melt. The polymer material feeding scale 201 is used to accurately deliver polymer modifiers, such as POE (polyolefin elastomer), to the second extruder 21. The inorganic filler feeding scale 202 is used to accurately deliver inorganic fillers, such as a mixture of glass fiber, carbon fiber, calcium carbonate, clay, talcum powder, etc., to the second extruder 21. The additive feeding scale 203 is used to accurately deliver additives, such as antioxidants and flame retardants commonly used on the market, to the second extruder 21. The polymer material feeding scale 201, the inorganic filler feeding scale 202 and the additive feeding scale 203 are all set as intermeshing block screws on the twin screw in the second extruder 2, see Figure 2 , respectively, are meshing block screw segments 211, 212, and 213. The remaining twin screws are conventional twin screws. The meshing block screw 211 corresponding to the polymer material feed scale 201 has a length of 4D; the meshing block screw 212 corresponding to the inorganic filler feed scale 202 has a length of 6D; and the meshing block screw 213 corresponding to the additive feed scale 203 has a length of 2D. The PP melt diverted from the main extrusion line 1 to the modified extrusion line 2 is first thoroughly mixed with the polymer modifier pumped in by the polymer feed scale 201 under the action of the corresponding meshing block screw, then thoroughly mixed with the inorganic filler delivered by the inorganic filler feed scale 202, and finally thoroughly mixed with the additive delivered by the additive feed scale 203. Under the action of the twin screws, the PP melt mixed with the polymer modifier, inorganic filler, and additives is extruded into the strand pelletizing device 22, ultimately obtaining modified PP particles.

[0055] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An online modified extrusion double granulation device, characterized in that, include: A main extrusion line comprises a first extruder, a melt pump, a filter device and a first pelletizing device, wherein the first extruder, the melt pump, the filter device and the first pelletizing device are connected in sequence; The modified extrusion line includes a second extruder, at least one functional material feed scale, and a second pelletizing device, wherein the second extruder is connected to the second pelletizing device, and the functional material feed scale is connected to the second extruder. The second extruder is a twin-screw extruder having at least one meshing block screw segment or toothed disk screw segment on its screw, and the position of the meshing block screw segment or toothed disk screw segment corresponds to the position of the functional material feed scale; The diversion pipeline is used to divert part of the melt in the main extrusion line to the modified extrusion line before the melt in the main extrusion line enters the first pelletizing device.

2. The online modified extrusion double granulation device according to claim 1, characterized in that, The first pelletizing device is an underwater pelletizing device.

3. The online modified extrusion double granulation device according to claim 1, characterized in that, The second pelletizing device is a strand pelletizing device.

4. The online modified extrusion double granulation device according to claim 1, characterized in that, The main extrusion line further comprises a drain valve, which is arranged between the melt pump and the filtering device.

5. The online modified extrusion double granulation device according to claim 1, characterized in that, The first extruder includes a pressure building section.

6. The online modified extrusion double granulation device according to claim 1, characterized in that, The functional material feeding scale is connected to the second extruder in a side feeding manner.

7. The online modified extrusion double granulation device according to claim 1, characterized in that: The modified extrusion line is connected to two or more functional material feeding scales.

8. The online modified extrusion double granulation device according to claim 1, characterized in that: The diversion pipeline includes a melt pipe, a buffer hopper, and a gear pump, which are connected in sequence; wherein the melt pipe is provided with a control valve and a drain valve, and the gear pump is arranged between the buffer hopper and the second extruder.

9. The online modified extrusion double granulation device according to claim 1, characterized in that: The melt pipe and buffer hopper are both provided with jacket insulation devices.

10. A PP online modified extrusion double granulation device, characterized in that, The device according to any one of claims 1 to 6 is used, wherein the first extruder is a twin-screw extruder, and the upstream section of the screw is a meshing block screw for completing the grinding and melting of PP powder; Preferably, the length of the engaging block screw is 5D.

11. The PP online modification extrusion double granulation device according to claim 10, characterized in that: The functional material feeding scale is configured such that a polymer material feeding scale and an inorganic filler feeding scale are sequentially connected to the second extruder along the direction of melt travel; Preferably, the length of the intermeshing block screw on the second extruder corresponding to the polymer material feeding scale is 4D; Preferably, the length of the intermeshing block screw on the second extruder corresponding to the inorganic filler feeding scale 202 is 6D.

12. The PP online modification extrusion double granulation device according to claim 11, characterized in that: The second extruder is also connected to an additive feeding scale; Preferably, the length of the intermeshing block screw on the second extruder corresponding to the additive feeding scale 203 is 2D.

13. The PP online modification extrusion double granulation device according to claim 10, characterized in that: The first extruder is also provided with a melt devolatilization section.

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