N-layer composite board co-extrusion module with concentration gradient and multi-layer co-extrusion equipment

Abstract

The present invention discloses an N-layer composite plate co-extrusion module with a concentration step, which is used for N-layer co-extrusion, and includes an extrusion device, a manifold, a mixing tube and a melt distributor which are sequentially connected and arranged along the flow direction of the fluid, and the extrusion device includes a first extruder and a second extruder. The present invention uses a partition arranged in the manifold and N mixing channels distributed from left to right formed in the mixing tube to achieve an ascending gradient change in the volume ratio of the basic material and the functional material in the N mixing channels from left to right, and then uses a melt distributor to stack the mixed materials flowing out of the N mixing tubes in order from top to bottom into N layers of materials. The N-layer composite plate co-extrusion module with a concentration step is further combined with an extrusion die to form a multi-layer co-extrusion device, which can realize multi-layer co-extrusion molding of more layers of composite plates with concentration steps with a smaller number of extrusion devices, and the volume ratio of the basic material and the functional material in each layer is an arbitrary preset ratio.

Description

Technical Field

[0001] The invention belongs to the technical field of wave absorbing materials, and in particular relates to an N-layer composite plate co-extrusion module with concentration steps and a multi-layer co-extrusion device. Background Art

[0002] With the rapid development of the electronics industry and the widespread application of electronic products, electromagnetic wave pollution can be seen everywhere in daily life. It not only reduces the service life of electronic products, but also causes certain harm to the human living environment. In order to improve the wave absorption strength and wave absorption frequency band width of electromagnetic wave absorbing materials, some researchers in this field prepare wave absorbing composite plates by multi-layer co-extrusion of multiple functional materials (such as the Chinese patent document with application number 201810593725.4), and some adjust the proportion of each component in the wave absorbing composite material, and make the wave absorbing composite plate by multi-layer co-extrusion of the composite material containing different component ratios. However, due to the technical defects of the multi-layer co-extrusion equipment in the prior art, the number of extruders required must correspond to the number of layers of the wave absorbing composite plate. Whether it is the equipment cost or the required assembly space, or the specific process, the number of layers of the wave absorbing composite plate is limited, and ultimately affects the wave absorption strength and the wave absorption frequency band width. Summary of the invention

[0003] In order to overcome the above problems in the prior art, the present invention provides an N-layer composite board co-extrusion module and a multi-layer co-extrusion device with a concentration gradient, which can realize the molding and preparation of composite boards with more layers with a smaller number of extruders.

[0004] In order to achieve the purpose of the present invention, the technical solution adopted by the present invention is: an N-layer composite plate co-extrusion module with a concentration gradient, used for N-layer co-extrusion, N is any integer greater than 2, including:

[0005] An extrusion device, the extrusion device comprising a first extruder for extruding a base material and a second extruder for extruding a functional material;

[0006] A manifold, wherein a partition is provided along the extension direction of the manifold, for dividing the internal flow channel of the manifold into a basic material flow channel and a functional material flow channel which are distributed up and down, wherein the inlet of the basic material flow channel is in sealed communication with the outlet of the first extruder, and the inlet of the functional material flow channel is in sealed communication with the outlet of the second extruder;

[0007] A mixing pipe is provided with a mixing channel along the extension direction of the mixing pipe, and the mixing channels are N in number and distributed from left to right, and are used to separate the basic material flowing out of the basic material channel and the functional material flowing out of the functional material channel into N strands at the same time, and make the volume ratio of the basic material and the functional material in each strand a preset ratio; the N mixing channels are provided with a mixing structure (further, the mixing structure is a static mixer or a spiral stirring rod, which is arranged in the mixing channel along the axis of the mixing channel, and is driven to rotate by a motor when in use. Static mixer The mixer can also be called a static mixer. Its basic working mechanism is to use the mixing unit body arranged in the mixing flow channel to change the flow state of the fluid in the mixing flow channel to achieve the purpose of good dispersion and sufficient mixing between different fluids. For example, it can be a convexity arranged in the mixing flow channel, a concave arranged in the mixing flow channel, a plurality of cross units formed by cross bars arranged in the mixing flow channel according to a certain rule (similar to the SX type static mixer) or a spiral sheet arranged in the mixing flow channel), which is used to mix the basic materials and functional materials in each strand to obtain a mixed material;

[0008] The melt distributor is used to stack the mixed materials flowing out of N mixing pipes in sequence from top to bottom to form N layers of materials.

[0009] In order to increase the width of the absorbing frequency band, the absorbing composite plate is often designed to be multi-layered, and the volume ratio of the basic material to the functional material in each layer is often variable. Therefore, in order to achieve this purpose, as a preference, the volume ratio of the basic material to the functional material in the N mixing channels changes gradiently from left to right according to the preset ratio. Furthermore, the volume ratio of the basic material to the functional material in the N mixing channels changes gradiently from left to right or decreases gradiently.

[0010] Furthermore, it also includes a connecting pipe, which is used to connect the manifold and the extrusion equipment, and has two flow channels formed in the connecting pipe, which are respectively used to be sealed and connected with the basic material flow channel and the functional material flow channel, and the basic material extruded by the first extruder enters the basic material flow channel through one of the flow channels, and the functional material extruded by the second extruder enters the functional material flow channel through the other flow channel. Furthermore, the connecting pipe and the manifold are detachably connected.

[0011] According to different wave absorption requirements, the number of layers of the wave absorbing composite plate and the volume ratio of the basic material and the functional material in each layer will be adaptively adjusted. In order to facilitate the adjustment, the manifold is preferably detachably connected to the extrusion equipment. The manifold includes a tube shell and a detachable liner placed in the tube shell. The partition is fixedly installed in the liner, and the basic material flow channel and the functional material flow channel are formed in the liner; the two ends of the tube shell are respectively provided with connecting flanges. When in use, the partitions with different shapes or different partition forms can be replaced according to the design requirements, so as to realize that the cross-section of the basic material flow channel and the functional material flow channel gradually changes in the left and right directions. As another implementation method: a slot is provided on the inner wall of the manifold, and the partition is detachably inserted into the manifold through the slot. Furthermore, the manifold is a rectangular tube, and the cross-section of the partition is straight or curved.

[0012] A multi-layer co-extrusion device, comprising the N-layer composite plate co-extrusion module with concentration steps as described above, and also comprising an extrusion die head, when the N-layer composite plate co-extrusion module with concentration steps is one, the feed port of the extrusion die head is connected to the outlet end of a melt distributor, and is used to extrude the N layers of material extruded by the N-layer composite plate co-extrusion module with concentration steps into N layers of composite plates with concentration steps;

[0013] When there are two or more co-extrusion modules for the N-layer composite plate with concentration steps, it also includes a co-extrusion adapter, in which a flow channel corresponding to the co-extrusion module for the N-layer composite plate with concentration steps and distributed from top to bottom is arranged, the flow channel inlet of the co-extrusion adapter is connected one-to-one with the outlet end of the melt distributor, and the flow channel outlet of the co-extrusion adapter is connected one-to-one with the feed port of the extrusion die head, and is used to sequentially co-extrude the N layers of material extruded by the co-extrusion module for the N-layer composite plate with concentration steps into a multi-layer composite plate with concentration steps, the number of layers of the multi-layer composite plate with concentration steps is the sum of the number of layers of the N layers of material extruded by each co-extrusion module for the N-layer composite plate with concentration steps, and the volume ratio of the basic material and the functional material in each layer of the multi-layer composite plate with concentration steps changes gradiently according to a preset value.

[0014] Compared with the prior art, the technical effect achieved by the present invention is as follows: based on the technical solution of the N-layer composite plate co-extrusion module with a concentration step, the volume ratio of the basic material and the functional material in the N-layer material can be realized at any preset ratio, and based on the multi-layer co-extrusion equipment based on the N-layer composite plate co-extrusion module with a concentration step, multi-layer co-extrusion molding of more layers of composite plates with concentration steps can be realized with a smaller number of extrusion equipment, and the volume ratio of the basic material and the functional material in each layer is any preset ratio.

[0015] This scheme can also be used to prepare N-layer composite boards with concentration steps such as heat insulation, UV protection and water and oxygen barrier materials, that is, the concentration of each material in each layer of the board is a set ratio, which can increase, decrease, or change in other regular or irregular ways. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of a co-extrusion module of an N-layer composite plate with concentration steps in an embodiment of the present invention (viewed from top).

[0017] Figure 2 for Figure 1 Cross-sectional view along the AA direction.

[0018] Figure 3 for Figure 1 Cross-sectional view along the BB direction (the mixing structure is not shown in the figure).

[0019] Figure 4 Schematic diagram of the structure of a co-extrusion module of an N-layer composite plate with concentration steps in an embodiment of the present invention (viewed from the right);

[0020] Figure 5 Schematic diagram of the structure of a melt distributor in a co-extrusion module of an N-layer composite plate with a concentration gradient in an embodiment of the present invention (viewed from top);

[0021] Figure 6 It is a structural schematic diagram (front view direction) of a melt distributor in a co-extrusion module of an N-layer composite plate with concentration steps in an embodiment of the present invention.

[0022] Figure 7 It is a schematic structural diagram (rearward view) of a melt distributor in a co-extrusion module of an N-layer composite plate with concentration steps in an embodiment of the present invention.

[0023] Figure 8 It is a schematic diagram of the structure of a multi-layer co-extrusion device in an embodiment of the present invention.

[0024] Fig. 9 The mixing structure of the present invention is a schematic structural diagram of a protrusion arranged in a mixing flow channel.

[0025] Fig.10 The mixing structure of the present invention is a schematic structural diagram of a depression arranged in a mixing flow channel.

[0026] Fig.11 The mixing structure of the present invention is a schematic structural diagram of a plurality of cross units formed by cross bars arranged in a mixing flow channel according to a certain rule.

[0027] Fig.12 The mixing structure of the present invention is a schematic structural diagram of a spiral sheet arranged in a mixing flow channel.

[0028] Fig.13 It is a schematic diagram of another arrangement of the partition of the present invention.

[0029] Fig.14 This is a schematic diagram of another arrangement of the partition of the present invention.

[0030] The reference numerals in the figure are: 1. extrusion die head, 2. melt distributor, 2-11. first flow channel, 2-12. first flow channel inlet, 2-13. first flow channel outlet, 2-21. second flow channel, 2-22. second flow channel inlet, 2-23. second flow channel outlet, 2-31. third flow channel, 2-32. third flow channel inlet, 2-33. third flow channel outlet, 3. mixing pipe, 4. manifold, 5. connecting pipe, 6. first extruder, 7. second extruder, 8. frame, 9. partition, 10. first mixing flow channel, 11. second mixing flow channel, 12. third mixing flow channel, 13. protrusion, 14. depression, 15. spiral sheet, 16. cross unit, 16-1. horizontal bar, 17. co-extrusion sleeve. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with embodiments:

[0032] See Figures 1 to 7 , an N-layer composite plate co-extrusion module with a concentration step, used for N-layer co-extrusion, N is any integer greater than 2 (N is equal to 3 in this embodiment), including an extrusion device, a manifold 4, a mixing pipe 3 and a melt distributor 2 connected in sequence along the fluid flow direction.

[0033] The extrusion equipment includes a first extruder 6 for extruding basic materials (such as polymer resins including polyethylene, polypropylene, polystyrene, polycarbonate, polymethyl methacrylate, polyamide, polyethylene terephthalate, etc., which are used to extrude basic materials such as films and sheets) and a second extruder 7 for extruding functional materials (such as: resistive absorbing materials such as silicon carbide and graphite used as absorbing fillers; dielectric absorbing materials such as barium titanate; magnetic dielectric absorbing materials such as ferrite and hydroxy iron; new absorbing materials including nanomaterials, chiral materials, conductive polymers, polycrystalline iron fibers and circuit simulation absorbing materials, etc.).

[0034] A partition 9 is provided along the extension direction of the manifold 4, which is used to separate the internal flow channel of the manifold 4 into a basic material flow channel and a functional material flow channel distributed vertically. The inlet of the basic material flow channel is tightly connected to the outlet of the first extruder 6, and the inlet of the functional material flow channel is tightly connected to the outlet of the second extruder 7.

[0035] A mixing channel is provided along the extension direction of the mixing tube 3. There are three mixing channels and they are distributed from left to right, and they are the first mixing channel 10, the second mixing channel 11 and the third mixing channel 12, respectively. The three mixing channels of this embodiment can separate the basic material flowing out of the basic material channel and the functional material flowing out of the functional material channel into three strands at the same time, and the volume ratio of the basic material and the functional material in each strand is a preset ratio; the three mixing channels are provided with a mixing structure, and the mixing structure is a static mixer or a spiral stirring rod. The spiral stirring rod is arranged in the mixing channel along the axis of the mixing channel. When in use, the spiral stirring rod is driven to rotate by a motor. In this embodiment, a spiral stirring rod is preferably used. A static mixer can also be called a static mixer. Its basic working mechanism is to use a mixing unit body arranged in the mixing channel to change the flow state of the fluid in the mixing channel, so as to achieve the purpose of good dispersion and sufficient mixing between different fluids. For example, it can be a protrusion 13 (see Fig. 9 ), the depression 14 (see Fig.10 ), or it may be a plurality of cross units 16 formed by cross bars arranged in the mixing flow channel according to a certain rule, such as Fig.11 (wherein the horizontal bar 16-1 is arc-shaped, of course, the horizontal bar 16-1 can also be straight or curved, etc.), similar to the SX type static mixer, or a spiral sheet 15 (such as Fig.12 ) is used to mix the basic materials and functional materials in each strand to obtain a mixed material; it is used to mix the basic materials and functional materials in each strand to obtain a mixed material.

[0036] The melt distributor 2 is used to stack the mixed materials flowing out of the three mixing pipes 3 in order from top to bottom to form three layers of materials. Figures 5 to 7 The melt distributor 2 is provided with three flow channels, namely the first flow channel 2-11, the second flow channel 2-21 and the third flow channel 2-31. The inlet of the first flow channel 2-12, the inlet of the second flow channel 2-22 and the inlet of the third flow channel 2-32 are arranged from left to right, and correspond to the first mixing flow channel 10, the second mixing flow channel 11 and the third mixing flow channel 12 one by one and are tightly connected; the outlet of the first flow channel 2-13, the outlet of the second flow channel 2-23 and the outlet of the third flow channel 2-33 are arranged from top to bottom.

[0037] In this embodiment, the basic material flow channel and the functional material flow channel are first separated by an inclined partition 9 which are arranged up and down and have a right-angled triangle cross-section, and then combined with the three mixing flow channels distributed on the left and right arranged in the mixing structure, the volume ratio of the basic material and the functional material in the three mixing flow channels changes in an ascending gradient from left to right.

[0038] According to different absorbing requirements, the number of layers of the absorbing composite plate and the volume ratio of the basic material and the functional material in each layer will be adaptively adjusted. In order to facilitate the adjustment, the manifold 4 is preferably detachably connected to the extrusion equipment. The manifold 4 includes a tube shell and a detachable liner placed in the tube shell. The partition 9 is fixedly installed in the liner, and the basic material flow channel and the functional material flow channel are both formed in the liner; the two ends of the tube shell are respectively provided with connecting flanges. When in use, the partition 9 with different shapes or different partition forms can be replaced according to the design requirements, so as to realize that the cross-section of the basic material flow channel and the functional material flow channel gradually changes in the left and right directions. As another implementation method: a slot is provided on the inner wall of the manifold 4, and the partition 9 is detachably inserted into the manifold 4 through the slot. Furthermore, the manifold 4 is a rectangular tube, and the cross-section of the partition 9 is straight or curved (the shape of the partition 9 in this embodiment is straight).

[0039] It also includes a connecting pipe 5, which is used to connect the manifold 4 and the extrusion equipment. Two flow channels are formed in the connecting pipe 5, which are respectively used for corresponding and sealed connections with the basic material flow channel and the functional material flow channel. The basic material extruded by the first extruder 6 enters the basic material flow channel through one of the flow channels, and the functional material extruded by the second extruder 7 enters the functional material flow channel through the other flow channel. The connecting pipe 5 and the manifold 4 are detachably connected. It should be noted that the co-extrusion equipment, connecting pipe 5, manifold 4 and mixing pipe 3 in this embodiment are all connected by flanges.

[0040] See Figure 5 A multi-layer co-extrusion device comprises at least one N-layer electromagnetic wave absorbing composite plate multi-layer co-extrusion module as described above, and also comprises an extrusion die head 1. When the N-layer composite plate co-extrusion module with a concentration step is one, the feed port of the extrusion die head 1 is connected to the outlet end of a melt distributor 2, so as to extrude the N layers of material extruded by the N-layer composite plate co-extrusion module with a concentration step into an N-layer composite plate with a concentration step.

[0041] When there are two or more co-extrusion modules for the N-layer composite plate with concentration steps, it also includes a co-extrusion adapter, in which a flow channel corresponding to the co-extrusion module for the N-layer composite plate with concentration steps and distributed from top to bottom is arranged, the flow channel inlet of the co-extrusion adapter is connected one-to-one with the outlet end of the melt distributor, and the flow channel outlet of the co-extrusion adapter is connected one-to-one with the feed port of the extrusion die head, and is used to sequentially co-extrude the N layers of material extruded by the co-extrusion module for the N-layer composite plate with concentration steps into a multi-layer composite plate with concentration steps, the number of layers of the multi-layer composite plate with concentration steps is the sum of the number of layers of the N layers of material extruded by each co-extrusion module for the N-layer composite plate with concentration steps, and the volume ratio of the basic material and the functional material in each layer of the multi-layer composite plate with concentration steps changes gradiently according to a preset value.

[0042] The specific number of the N-layer electromagnetic wave absorbing composite plate multilayer co-extrusion modules can be adjusted according to actual needs. In this embodiment, three N-layer electromagnetic wave absorbing composite plate multilayer co-extrusion modules as described above are arranged. The specific extrusion die head 1 is connected to the N-layer electromagnetic wave absorbing composite plate multilayer co-extrusion module through the co-extrusion adapter 17. In this embodiment, the co-extrusion adapter 17 is provided with three flow channels distributed up and down, which respectively receive the N layers of materials extruded by the three N-layer electromagnetic wave absorbing composite plate multilayer co-extrusion modules, and distribute the N layers of materials up and down in sequence, and then enter the extrusion die head 1 to be extruded into a multilayer electromagnetic wave absorbing composite plate. The number of layers of the multilayer electromagnetic wave absorbing composite plate is 9.

[0043] The N-layer electromagnetic wave absorbing composite board multilayer co-extrusion module and multilayer co-extrusion equipment of this embodiment can also be used to prepare N-layer composite boards with concentration steps such as heat insulation, UV protection and water and oxygen barrier materials, that is, the concentration of each material in each layer of the board is a set ratio, which can be increased, decreased, or changed in other regular or irregular ways.

[0044] The partition plate 9 used to separate the internal flow channel of the manifold 4 into the basic material flow channel and the functional material flow channel distributed up and down can be of various shapes or in various configurations. Fig.13 , which is another arrangement mode of the partition of the present invention, see Fig.14 , which is another arrangement method of the partition of the present invention.

[0045] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0046] The present invention is not limited to the following specific embodiments. A person skilled in the art can implement the present invention in various other specific embodiments according to the contents disclosed in the present invention, or any simple changes or modifications made to the design structure and ideas of the present invention fall within the protection scope of the present invention. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0047] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0048] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

Claims

1. A N-layer composite board co-extrusion module with concentration gradient, characterized in that: For N-layer co-extrusion, N is any integer greater than 2, including: An extrusion device, the extrusion device comprising a first extruder (6) for extruding a basic material and a second extruder (7) for extruding a functional material; The manifold (4) is provided with a partition (9) along the extension direction of the manifold (4) for dividing the internal flow channel of the manifold (4) into a basic material flow channel and a functional material flow channel distributed vertically. The inlet is in sealed communication with the outlet of the first extruder (6), and the inlet of the functional material flow channel is in sealed communication with the outlet of the second extruder (7); A mixing pipe (3) is provided with mixing channels along the extension direction of the mixing pipe (3), wherein the mixing channels are N in number and are distributed from left to right, and are used to separate the basic material flowing out of the basic material channel and the functional material flowing out of the functional material channel into N strands at the same time, and to make the volume ratio of the basic material to the functional material in each strand to be a preset ratio; each of the N mixing channels is provided with a mixing structure, and is used to mix the basic material and the functional material in each strand to obtain a mixed material, wherein the basic material and the functional material in the mixed material are well dispersed and fully mixed; The melt distributor (2) is used to stack the mixed materials flowing out of the N mixing pipes (3) in order from top to bottom to form N layers of material; The volume ratio of the basic material and the functional material in the N mixing channels changes gradually from left to right according to the preset ratio; The mixing structure is a static mixer or a spiral stirring rod, and the spiral stirring rod is arranged in the mixing flow channel along the axial direction of the mixing flow channel. When in use, the spiral stirring rod is driven to rotate by a motor; The static mixer is a protrusion (13) arranged in the mixing flow channel, a depression (14) arranged in the mixing flow channel, a spiral sheet (15) arranged in the mixing flow channel, or a plurality of cross units arranged in the mixing flow channel, wherein the cross units are composed of horizontal bars (16-1) cross-arranged in the mixing flow channel, and the horizontal bars are straight or curved.

2. The N-layer composite board co-extrusion module with concentration gradient according to claim 1, characterized in that: The horizontal strip (16-1) is arc-shaped.

3. The N-layer composite board co-extrusion module with concentration gradient according to claim 1, characterized in that: The volume ratio of the basic material to the functional material in the N mixing channels changes in an ascending gradient or a descending gradient from left to right.

4. The N-layer composite board co-extrusion module with concentration gradient according to claim 1, characterized in that: The device also includes a connecting pipe (5) for connecting the manifold (4) and the extrusion device. The connecting pipe (5) is formed with two flow channels for correspondingly and hermetically connecting with the basic material flow channel and the functional material flow channel, respectively. The basic material extruded by the first extruder (6) enters the basic material flow channel via one of the flow channels, and the functional material extruded by the second extruder (7) enters the functional material flow channel via the other flow channel.

5. The N-layer composite board co-extrusion module with concentration gradient according to claim 4, characterized in that: The connecting pipe (5) and the manifold (4) are detachably connected.

6. The N-layer composite board co-extrusion module with concentration gradient according to claim 1, characterized in that: The manifold (4) is detachably connected to the extrusion device, the manifold (4) comprises a tube shell and a detachable liner placed in the tube shell, the partition (9) is fixedly installed in the liner, and the basic material flow channel and the functional material flow channel are both formed in the liner; both ends of the tube shell are provided with connection flanges; Alternatively, the manifold (4) is detachably connected to the extrusion device, a slot is provided on the inner wall of the manifold (4), and the partition (9) is detachably inserted into the manifold (4) through the slot.

7. The N-layer composite board co-extrusion module with concentration gradient according to claim 1, characterized in that: The manifold (4) is a rectangular tube, and the cross section of the partition (9) is straight or curved.

8. A multi-layer co-extrusion device, characterized in that: The invention comprises an N-layer composite plate co-extrusion module with a concentration step as claimed in any one of claims 1 to 6, and further comprises an extrusion die head (1). When the N-layer composite plate co-extrusion module with a concentration step is one, the feed port of the extrusion die head (1) is connected to the outlet end of a melt distributor (2), and is used for extruding the N layers of material extruded by the N-layer composite plate co-extrusion module with a concentration step into an N-layer composite plate with a concentration step; When there are more than two N-layer composite board co-extrusion modules with concentration steps, the method further comprises a co-extrusion adapter (17), wherein a flow channel corresponding to the N-layer composite board co-extrusion modules with concentration steps and distributed from top to bottom is arranged in the co-extrusion adapter (17), the flow channel inlet of the co-extrusion adapter (17) is connected to the outlet end of the melt distributor (2) in a one-to-one correspondence, and the flow channel outlet of the co-extrusion adapter (17) is connected to the feed port of the extrusion die head (1) in a one-to-one correspondence, and is used to sequentially co-extrude the N layers of material extruded by the N-layer composite board co-extrusion modules with concentration steps into a multi-layer composite board with concentration steps, wherein the number of layers of the multi-layer composite board with concentration steps is the sum of the number of layers of the N layers of material extruded by each of the N-layer composite board co-extrusion modules with concentration steps, and the volume ratio of the basic material to the functional material in each layer of the multi-layer composite board with concentration steps changes in a gradient according to a preset value.

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