Supercritical fluid assisted polymer extrusion foaming apparatus based on melt self-sealing

Abstract

The application discloses a supercritical fluid assisted polymer extrusion foaming device based on melt self-sealing, which comprises a cylinder, an extrusion screw and an extrusion screw driving device; the extrusion screw comprises a key connecting section, a threaded sealing section, a compression section, a separation section and a transportation section; the compression section and the transportation section are provided with helical screw ribs with opposite rotation directions; the compression section screw rib and the inner wall of the cylinder form a high-pressure melt cavity, the bottom diameter of the compression section screw rib gradually increases from front to back, and the transportation section screw rib and the inner wall of the cylinder form a melt extrusion cavity; the cylinder is provided with a first feeding port and a discharging port which are communicated with the high-pressure melt cavity, and is provided with a second feeding port and a third feeding port which are communicated with the melt extrusion cavity; a bypass valve for adjusting the pressure of the homogeneous solution in the high-pressure melt cavity is further connected between the discharging port and the third feeding port. The application effectively solves the problems that the supercritical fluid is easy to separate from the polymer melt and the gas is easy to leak from the gap at the tail end of the extrusion screw during the extrusion process, and belongs to the polymer extrusion foaming device.

Description

Technical Field

[0001] This invention relates to polymer extrusion foaming apparatus, and more specifically to a cooling extruder in the second stage of a two-stage extruder. Background Technology

[0002] Supercritical fluid extrusion foaming is an advanced polymer material processing technology. During extrusion, a supercritical fluid (usually a non-reactive gas such as carbon dioxide or nitrogen) is first injected into the extruder barrel. Under the shearing and mixing action of the screw, the supercritical fluid rapidly diffuses and dissolves in the polymer melt, forming a homogeneous polymer / supercritical fluid solution. Then, the homogeneous solution is extruded through the extruder die. Due to the enormous pressure drop during extrusion, the dissolved supercritical fluid rapidly precipitates, inducing a large number of bubble nuclei in the extruded melt. During the subsequent cooling process, the bubble nuclei inside the extruded melt continuously grow and solidify, ultimately yielding microporous foamed plastic extruded products. These microporous plastic products, produced based on supercritical fluid extrusion foaming technology, are lightweight, have high specific strength, and possess excellent shock load absorption capabilities, as well as advantages such as thermal insulation, sound insulation, damping, electrical insulation, and corrosion resistance. Therefore, they are widely used in industries such as construction, automotive, pharmaceuticals, footwear, electronics, and food packaging.

[0003] Currently, equipment types for supercritical fluid-assisted extrusion molding of microcellular foamed plastic parts (including sheets, plates, profiles, films, etc.) include single-screw, twin-screw, and two-stage extruders. Among them, the two-stage extruder consists of two independent extrusion units (i.e., a foaming extruder and a cooling extruder) connected in series. The foaming extruder is mainly responsible for melting and plasticizing the plastic particles and injecting and mixing the supercritical fluid to form a homogeneous polymer / supercritical fluid solution; the cooling extruder is mainly responsible for the precise control of the homogeneous solution temperature to stably and with high quality extrude and mold the desired foamed parts. Because of its comprehensive advantages such as high production efficiency, stable product quality, and low energy consumption, the two-stage extruder is the most widely used molding equipment in the extrusion foaming industry.

[0004] One of the key technical challenges in supercritical fluid extrusion foaming production using a two-stage extruder is preventing the supercritical fluid dissolved in the polymer melt from precipitating out due to localized pressure drops during the transfer of the homogeneous polymer / supercritical fluid solution from the foaming extruder to the cooling extruder. This precipitated gas then leaks through the mechanical assembly gap at the tail of the cooling extruder. Gas leakage significantly reduces the concentration of supercritical fluid dissolved in the polymer melt, affecting foaming performance and reducing the quality of the extruded foamed parts. Current solutions involve installing graphite packing at the tail of the cooling extruder barrel to seal the screw-barrel assembly gap and prevent gas leakage. However, during operation, the high-speed rotation of the screw within the barrel causes deformation and wear of the graphite packing. Therefore, the tail of the cooling extruder needs periodic disassembly and replacement of the graphite packing to maintain the seal. This not only increases maintenance costs but also affects continuous equipment operation, significantly reducing the production efficiency of the extrusion foaming process. Summary of the Invention

[0005] To address the technical problems existing in the prior art, the purpose of this invention is to provide a supercritical fluid-assisted polymer extrusion foaming device based on melt self-sealing, so as to solve the problems in the prior art where supercritical fluid is easily separated from the polymer melt and the separated gas is easily leaked from the gap at the tail end of the cooling extruder.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A supercritical fluid-assisted polymer extrusion foaming device based on melt self-sealing includes a barrel, an extrusion screw disposed in the barrel, and an extrusion screw drive device connected to the rear end of the extrusion screw. The extrusion screw includes, from back to front, a keyed connection section, a threaded sealing section, a compression section, a separation section, and a transport section. The separation section is cylindrical and has a clearance fit with the inner hole of the barrel. The compression section and the transport section are provided with helical ribs of opposite rotation. The helical ribs of the compression section and the inner wall of the barrel form a high-pressure melt cavity, and the bottom diameter of the helical ribs of the compression section gradually increases from front to back along the extrusion direction of the homogeneous solution in the high-pressure melt cavity. The helical ribs of the transport section and the inner wall of the barrel form a melt extrusion cavity. The barrel is provided with a first inlet and an outlet communicating with the high-pressure melt cavity. The barrel is also provided with a second inlet and a third inlet communicating with the melt extrusion cavity. A bypass valve that can adjust the pressure of the homogeneous solution in the high-pressure melt cavity is connected between the outlet and the third inlet.

[0008] Preferably, the gap between the separator and the inner hole of the barrel is 0.02-0.1 mm.

[0009] Preferably, the bypass valve includes a valve body, a conical valve core, a spring, an adjusting screw, an end cap, and a pressure sensor. The valve body has a feed hole, a discharge hole, and a stepped hole drilled in it. The feed hole and discharge hole are respectively connected to the small-diameter hole of the stepped hole. The conical valve core includes a flange end and a conical end. The flange end is located in the large-diameter hole of the stepped hole, and the conical end is located in the small-diameter hole of the stepped hole with a clearance fit. When the conical valve core slides axially along the stepped hole, the conical end connects or blocks the discharge hole from the small-diameter hole of the stepped hole. After the adjusting screw is connected to the threaded through hole of the end cap, the bottom end of the adjusting screw is inserted into the large-diameter hole of the stepped hole. The spring is located in the large-diameter hole of the stepped hole and is compressed between the bottom end face of the adjusting screw and the top end face of the flange end of the conical valve core. The end cap is fixed to one end of the valve body by a screw. The pressure sensor is installed in the valve body, and the measuring end of the pressure sensor is connected to the small-diameter hole of the stepped hole in the valve body.

[0010] Preferably, the feed port of the bypass valve is connected to the discharge port on the material cylinder through a feed pipe; the discharge port of the bypass valve is connected to the third feed port on the material cylinder through a discharge pipe.

[0011] Preferably, a sealing ring is provided between the conical end of the conical valve core and the inner wall of the small diameter hole of the stepped hole to prevent the homogeneous solution from flowing out into the large diameter hole of the stepped hole.

[0012] Preferably, the supercritical fluid-assisted polymer extrusion foaming device based on melt self-sealing further includes a connector, through which the die of the foaming extruder is connected to the barrel; the connector has one inlet and two outlets, and a fluid channel is provided inside the connector, with the two outlets connected to the inlet in parallel through the fluid channel, the inlet communicating with the die of the foaming extruder, and the two outlets communicating with the first feed port and the second feed port of the barrel respectively.

[0013] Preferably, the extrusion screw drive device includes an extrusion motor and a reducer; the extrusion motor is connected to the input end of the reducer, the output shaft of the reducer is connected to the key connection section of the extrusion screw, and the rear end of the barrel is connected to the flange of the output end of the reducer.

[0014] Preferably, a heating device is provided on the outer wall of the barrel; a heating device is also provided on the outer surface of the valve body. The heating device can be an electric heating coil, an electromagnetic induction coil, or an infrared heating cylinder, etc.

[0015] Preferably, the axial direction of the extrusion screw and the barrel is arranged in the horizontal direction, the first feed port and the second feed port are located at the upper end of the barrel, and the discharge port and the third feed port are located at the lower end of the barrel.

[0016] Preferably, the heating device is an electric heating coil, an electromagnetic induction coil, or an infrared heating cylinder.

[0017] Preferably, the pressure of the homogeneous solution in the high-pressure melt chamber is controlled by adjusting the pre-compression of the spring in the bypass valve.

[0018] The working principle of this invention is as follows: The polymer / supercritical fluid homogeneous solution formed in the foaming extruder is diverted by the connector and enters the high-pressure melt chamber and the melt extrusion chamber through the first and second feed ports of the barrel, respectively. Because the compression section and conveying section of the extrusion screw have oppositely rotating screw threads, the homogeneous solution entering the melt extrusion chamber is continuously conveyed along the front end of the extrusion screw under the rotational action of the extrusion screw, while the homogeneous solution entering the high-pressure melt chamber is continuously conveyed along the tail end of the extrusion screw. Since the bottom diameter of the screw threads in the compression section of the extrusion screw gradually increases along the extrusion direction of the melt in the high-pressure melt chamber, the homogeneous solution entering the high-pressure melt chamber is continuously compressed while being continuously conveyed, thereby forming a high-pressure zone for the homogeneous solution in the high-pressure melt chamber. The pressure of the homogeneous solution in the high-pressure melt chamber can be flexibly controlled by adjusting the pre-compression of the spring in the bypass valve. When the pressure of the homogeneous solution in the high-pressure zone exceeds the saturation pressure of the supercritical fluid, the resulting high-pressure zone not only makes it difficult for the supercritical fluid dissolved in the polymer melt to precipitate, but also prevents the precipitated gas from leaking out from the mechanical gap at the tail of the extrusion screw, thus achieving a self-sealing effect. The high-pressure homogeneous solution in the high-pressure melt chamber enters the melt extrusion chamber through the third feed port of the barrel after passing through the bypass valve. After mixing with the homogeneous solution here, it is continuously extruded and molded to finally obtain the desired microporous foamed part.

[0019] The present invention has the following advantages:

[0020] (1) The supercritical fluid-assisted polymer extrusion foaming device provided by the present invention can form a high-pressure melt zone at the tail end of the extrusion screw to produce a self-sealing effect, which can effectively solve the problems of supercritical fluid easily precipitating from the polymer melt and gas leakage from the gap at the tail end of the extrusion screw.

[0021] (2) Compared with the prior art, the supercritical fluid-assisted polymer extrusion foaming device based on melt self-sealing provided by the present invention does not require regular disassembly and maintenance, thereby effectively ensuring the continuous operation of extrusion foaming production and realizing the efficient and high-quality production of microporous plastic parts.

[0022] (3) The present invention has the advantages of simple structure and stable production process, and is easy to promote and apply in extrusion foaming industrial production.

[0023] (4) The connector is designed to better integrate the present invention with the foaming extruder in terms of structure. The fluid channel structure of the connector is designed so that the polymer / supercritical fluid homogeneous solution transported from the foaming extruder can be proportionally split into the high-pressure melt chamber and the melt extrusion chamber. Attached Figure Description

[0024] Figure 1This is a schematic diagram of the structure of the supercritical fluid-assisted polymer extrusion foaming device based on melt self-sealing according to the present invention.

[0025] Figure 2 yes Figure 1 A magnified view of a portion of point A in the middle.

[0026] Figure 3 This is a schematic diagram of the extrusion screw.

[0027] Figure 4 This is a schematic diagram of the material cylinder structure.

[0028] Figure 5 This is a schematic diagram of the explosion of a bypass valve.

[0029] The labels in the above figures are explained as follows: 1—Barrel; 1-1—First feed inlet; 1-2—Discharge outlet; 1-3—Second feed inlet; 1-4—Third feed inlet; 2—Extrusion screw; 2-1—Key connection section; 2-2—Threaded sealing section; 2-3—Compression section; 2-4—Separation section; 2-5—Transportation section; 3—High-pressure melt chamber; 4—Mel extrusion chamber; 5—Bypass valve; 5-1—Valve body; 5-2—Conical valve core; 5-3—Spring; 5-4—Adjusting screw; 5-5—End cap; 5-6—Pressure sensor; 5-7—Feed hole; 5-8—Discharge hole; 5-9—Stepped hole; 5-10—Sealing ring; 6—Feed pipe; 7—Discharge pipe; 8—Extrusion motor; 9—Reducer; 10—Connector; 11—Foaming extruder; 12—Electric heating coil. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0031] Figure 1-5The present invention illustrates the specific structure of a supercritical fluid-assisted polymer extrusion foaming device based on melt self-sealing, comprising a barrel 1, an extrusion screw 2 disposed within the barrel, and an extrusion screw drive device connected to the rear end of the extrusion screw. The extrusion screw 2 is sequentially provided with a keyed connection section 2-1, a threaded sealing section 2-2, a compression section 2-3, a separation section 2-4, and a conveying section 2-5. The separation section 2-4 is cylindrical and has a clearance fit with the inner bore of the barrel 1, with a clearance size of 0.02-0.1 mm. The extrusion screw 2 has a compression section 2-3 and a conveying section 2-5 with helical ribs of opposite directions of rotation (e.g., the screw ribs of the compression section 2-3 are left-handed, and the screw ribs of the conveying section 2-5 are right-handed). The screw ribs of the compression section 2-3 and the inner wall of the barrel 1 form a high-pressure melt cavity 3, and the bottom diameter of the screw ribs of the compression section 2-3 gradually increases along the extrusion direction of the melt in the high-pressure melt cavity 3. The screw ribs of the conveying section 2-5 and the inner wall of the barrel 1 form a melt extrusion cavity 4. The barrel 1 is provided with a first feed port 1-1 and a discharge port 1-2 that communicate with the high-pressure melt cavity 3. The barrel 1 is also provided with a second feed port 1-3 and a third feed port 1-4 that communicate with the melt extrusion cavity 4. A bypass valve 5 that can adjust the pressure of the homogeneous solution in the high-pressure melt cavity is connected between the discharge port 1-2 and the third feed port 1-4.

[0032] like Figure 2 and 5 As shown, the bypass valve 5 includes a valve body 5-1, a conical valve core 5-2, a spring 5-3, an adjusting screw 5-4, an end cap 5-5, and a pressure sensor 5-6. The valve body 5-1 has a feed hole 5-7, a discharge hole 5-8, and a stepped hole 5-9 drilled in it. The feed hole 5-7 and the discharge hole 5-8 are respectively connected to the two ends of the small-diameter hole of the stepped hole 5-9. The conical valve core 5-2 includes a flange end and a conical end. The flange end is installed in the large-diameter hole of the stepped hole, and the conical end is installed in the small-diameter hole of the stepped hole 5-9 with a clearance fit. The length of the conical end is preferably such that when the conical valve core 5-2 slides back and forth in the stepped hole 5-9, the small-diameter hole of the stepped hole 5-9 and the discharge hole 5-8 can achieve either a "connected" or "blocked" state. After the adjusting screw 5-4 is connected to the threaded through hole of the end cap 5-5, its bottom end is inserted into the large-diameter hole of the stepped hole 5-9. Spring 5-3 is disposed within the large-diameter hole of stepped hole 5-9, with its two ends tightly fitted to the bottom end face of adjusting screw 5-4 and the top end face of flange of conical valve core 5-2, respectively. End cap 5-5 is fixed to one end of valve body 5-1 by screws. Pressure sensor 5-6 is disposed in valve body 5-1, with its measuring end communicating with the small-diameter hole of stepped hole 5-9 in valve body 5-1. In addition, a sealing ring 5-10 is provided between the conical end of conical valve core 5-2 and the inner wall of small-diameter hole of stepped hole 5-9 to prevent homogeneous solution in small-diameter hole from flowing out to large-diameter hole. Stepped hole is a two-stage hole, including large-diameter hole and small-diameter hole. Inlet and outlet holes are both connected to and perpendicular to small-diameter hole. Outlet hole is located at the end closer to large-diameter hole, and inlet hole is located at the end farther from large-diameter hole.

[0033] The feed port 5-7 of the bypass valve 5 is connected to the discharge port 1-2 on the material cylinder 1 through the feed pipe 6, and the discharge port 5-8 of the bypass valve 5 is connected to the third feed port 1-4 on the material cylinder 1 through the discharge pipe 7.

[0034] like Figure 1 As shown, the extrusion screw drive device includes an extrusion motor 8 and a reducer 9. The extrusion motor 8 is connected to the input end of the reducer 9, the output shaft of the reducer 9 is connected to the key connection section 2-1 of the extrusion screw 2, and the tail end of the barrel 1 is connected to the flange of the output end of the reducer 9.

[0035] like Figure 1 As shown, the first feed port 1-1 and the second feed port 1-3 of the barrel are respectively connected to the die of the foaming extruder 11 through the connecting body 10. The connecting body has one inlet and two outlets. A fluid channel is provided inside the connecting body. The two outlets are connected to the inlet in parallel through the fluid channel. The inlet is connected to the die of the foaming extruder. The two outlets are respectively connected to the first feed port and the second feed port of the barrel.

[0036] In addition, an electric heating coil 12 is provided on the outer wall of the barrel 1, and an electric heating coil 12 is also provided on the outer surface of the valve body of the bypass valve 5.

[0037] The extrusion screw and barrel are axially aligned horizontally. The first and second feed inlets are located at the upper end of the barrel, while the discharge port and third feed inlet are located at the lower end. The connector is located at the upper end, and the bypass valve is located at the lower end.

[0038] The working process of the supercritical fluid-assisted polymer extrusion foaming device based on melt self-sealing is as follows: First, the electric heating coils 12 set on the outer wall of the barrel 1 and the surface of the bypass valve 5 heat the barrel 1 and valve body 5-1 to above the polymer melting temperature (e.g., 180°C). After the temperature stabilizes, the extrusion motor 8 is started. The output torque of the extrusion motor 8 is amplified by the reducer 9 and drives the extrusion screw 2 to rotate. Then, the polymer / supercritical carbon dioxide homogeneous solution formed in the foaming extruder 11 is diverted by the connector 10 and enters the high-pressure melt chamber 3 and the melt extrusion chamber 4 through the first feed port 1-1 and the second feed port 1-3 of the barrel, respectively. Since the compression section 2-3 and the conveying section 2-5 of the extrusion screw 2 are provided with screw edges of opposite rotation, under the rotation of the extrusion screw 2, the homogeneous solution entering the melt extrusion chamber 4 will be continuously conveyed along the front end of the extrusion screw 2, while the homogeneous solution entering the high-pressure melt chamber 3 will be continuously conveyed along the tail end of the extrusion screw. Because the bottom diameter of the screw ribs in the compression section 2-3 of the extrusion screw 2 gradually increases along the extrusion direction of the melt in the high-pressure melt chamber 3, the homogeneous solution entering the high-pressure melt chamber 3 is continuously compressed while being continuously transported, thus forming a high-pressure zone for the homogeneous solution in the high-pressure melt chamber 3. Subsequently, the high-pressure homogeneous solution in the high-pressure melt chamber 3 enters the small-diameter hole of the stepped hole 5-9 in the valve body 5-1 through the discharge port 1-2 of the barrel, the feed pipe 6, and the feed hole 5-7 of the bypass valve 5. At this time, rotating the adjusting screw 5-4 causes the spring 5-3 to generate a certain pre-compression amount, while observing the pressure value of the pressure sensor 5-6. When the pressure of the homogeneous solution gradually increases to the preset value (such as 15MPa, which is usually higher than the saturation pressure of supercritical carbon dioxide), the rotation of the adjusting screw 5-4 is stopped, thus stabilizing the pressure of the homogeneous solution in the high-pressure melt chamber 3 at the preset pressure level. Because the pressure of the homogeneous solution in the high-pressure melt chamber 3 exceeds the saturation pressure of supercritical carbon dioxide (e.g., 7.38 MPa), not only is it difficult for dissolved supercritical carbon dioxide to precipitate from the polymer melt, but it also prevents the carbon dioxide gas that has already precipitated from the polymer melt from passing through the high-pressure zone and leaking out from the mechanical gap at the tail of the extrusion screw 2. Finally, the high-pressure homogeneous solution in the small-diameter holes of the stepped holes 5-9 enters the melt extrusion chamber 4 through the discharge holes 5-8 of the bypass valve 5, the discharge pipe 7, and the third feed port 1-4 of the barrel 1. After mixing with the homogeneous solution here, it is continuously extruded and molded to finally obtain the desired microporous foamed part.

[0039] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A supercritical fluid-assisted polymer extrusion foaming device based on melt self-sealing, comprising a barrel, an extrusion screw disposed in the barrel, and an extrusion screw drive device connected to the rear end of the extrusion screw, characterized in that: The extrusion screw includes, from back to front, a keyed connection section, a threaded sealing section, a compression section, a separation section, and a conveying section. The separation section is cylindrical and has a clearance fit with the inner bore of the barrel. The compression section and the conveying section are provided with helical ribs of opposite directions of rotation. The helical ribs of the compression section and the inner wall of the barrel form a high-pressure melt cavity, and the bottom diameter of the helical ribs of the compression section gradually increases from front to back along the extrusion direction of the homogeneous solution in the high-pressure melt cavity. The helical ribs of the conveying section and the inner wall of the barrel form a melt extrusion cavity. The barrel is provided with a first inlet and an outlet communicating with the high-pressure melt cavity. The barrel is also provided with a second inlet and a third inlet communicating with the melt extrusion cavity. A bypass valve that can adjust the pressure of the homogeneous solution in the high-pressure melt cavity is connected between the outlet and the third inlet. The bypass valve includes a valve body, a conical valve core, a spring, an adjusting screw, an end cap, and a pressure sensor. The valve body has a feed port, a discharge port, and a stepped hole. The feed port and discharge port are connected to the small-diameter hole of the stepped hole. The conical valve core includes a flange end and a conical end. The flange end is located within the large-diameter hole of the stepped hole, and the conical end is located within the small-diameter hole of the stepped hole with a clearance fit. When the conical valve core slides axially along the stepped hole, the conical end connects or blocks the discharge port from the small-diameter hole of the stepped hole. After the adjusting screw is connected to the threaded through hole of the end cap, the bottom end of the adjusting screw is inserted into the large-diameter hole of the stepped hole. The spring is located within the large-diameter hole of the stepped hole and is compressed between the bottom end face of the adjusting screw and the top end face of the flange end of the conical valve core. The end cap is fixed to one end of the valve body by a screw. The pressure sensor is installed in the valve body, and the measuring end of the pressure sensor is connected to the small-diameter hole of the stepped hole in the valve body. The axial direction of the extrusion screw and the barrel is set horizontally, the first and second feed ports are located at the upper end of the barrel, and the discharge port and the third feed port are located at the lower end of the barrel; The feed port of the bypass valve is connected to the discharge port on the barrel through a feed pipe; the discharge port of the bypass valve is connected to the third feed port on the barrel through a discharge pipe.

2. The supercritical fluid-assisted polymer extrusion foaming device based on melt self-sealing according to claim 1, characterized in that: The gap between the separator and the inner hole of the barrel is 0.02-0.1 mm.

3. The supercritical fluid-assisted polymer extrusion foaming device based on melt self-sealing according to claim 1, characterized in that: A sealing ring is also provided between the conical end of the conical valve core and the inner wall of the small diameter hole of the stepped hole to prevent the homogeneous solution from flowing out into the large diameter hole of the stepped hole.

4. The supercritical fluid-assisted polymer extrusion foaming device based on melt self-sealing according to claim 1, characterized in that: It also includes a connector, through which the die of the foaming extruder is connected to the barrel; the connector has one inlet and two outlets, and a fluid channel is provided inside the connector. The two outlets are connected to the inlet in parallel through the fluid channel. The inlet is connected to the die of the foaming extruder, and the two outlets are connected to the first feed port and the second feed port of the barrel, respectively.

5. The supercritical fluid-assisted polymer extrusion foaming device based on melt self-sealing according to claim 1, characterized in that: The extrusion screw drive unit includes an extrusion motor and a reducer; the extrusion motor is connected to the input end of the reducer, the output shaft of the reducer is connected to the keyed section of the extrusion screw, and the rear end of the barrel is connected to the flange at the output end of the reducer.

6. The supercritical fluid-assisted polymer extrusion foaming device based on melt self-sealing according to claim 1, characterized in that: A heating device is installed on the outer wall of the barrel; a heating device is also installed on the outer surface of the valve body.

7. The supercritical fluid-assisted polymer extrusion foaming device based on melt self-sealing according to claim 1, characterized in that: The pressure of the homogeneous solution in the high-pressure melt chamber is controlled by adjusting the pre-compression of the spring in the bypass valve.

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