Production process and system of ultraviolet resistant polyethylene terephthalate film

Abstract

The application discloses a kind of production process and system of ultraviolet-resistant polyethylene terephthalate film, belong to film production technical field.The production process includes: after PET chip and anti-ultraviolet master batch are mixed respectively after drying, melt blend is obtained by double-screw extruder, is casted by extrusion die head, and the film substrate is formed by biaxial stretching, then the film substrate is carried out online double-side synchronous pre-coating and heat curing shaping treatment, finally, finished film is obtained by winding.The application realizes the double ultraviolet-resistant protective effect of film by the composite mode of internal blending modification of substrate and online double-side coating protection, discards the complicated process of traditional offline coating, improves production efficiency, improves film stress unevenness, warping defect;At the same time, it is matched with special linkage feeding system, guarantees material conveying stability, cooperates with accurate material drying process, effectively improves film forming quality and comprehensive performance, and is suitable for high-end ultraviolet-resistant PET film large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of thin film production technology, and particularly relates to a process and system for producing ultraviolet-resistant polyethylene terephthalate (PET) films. Background Technology

[0002] Polyethylene terephthalate (PET) film has excellent mechanical and optical properties and is widely used in photovoltaic and electronics fields. Existing UV-resistant PET films are divided into two types: one type uses a substrate blending method with UV-resistant masterbatch, which can impart weather resistance to the film itself, but simple substrate blending is difficult to achieve reliable double-sided surface protection; the other type uses an offline double-sided coating process to prepare the protective coating. Offline processing requires secondary transfer treatment, which involves many steps and low production efficiency. The step-by-step coating process can also easily lead to inconsistent stress on the two sides of the film, resulting in warping and affecting the film's performance. Summary of the Invention

[0003] The purpose of this invention is to address the aforementioned technical problems by providing a UV-resistant polyethylene terephthalate (PET) film production process and system. This system combines UV-resistant masterbatch blended within the substrate with online double-sided synchronous pre-coating, thus balancing the UV resistance of the film itself with the protective effect on both surfaces. This reduces offline secondary processing steps, improves production efficiency, addresses the issues of uneven stress and warping on both sides of the film, and ensures the film's performance.

[0004] In view of this, the present invention provides a process for producing a UV-resistant polyethylene terephthalate film, comprising the following steps: S1. Take polyethylene terephthalate chips and UV-resistant masterbatch according to the preset ratio, and dry the polyethylene terephthalate chips and UV-resistant masterbatch respectively. S2. The dried polyethylene terephthalate chips are mixed with the UV-resistant masterbatch, and the mixture is then fed into a twin-screw extruder. S3. The mixed polyethylene terephthalate chips and UV-resistant masterbatch are melt-blended using a twin-screw extruder to obtain a melt-blended material. S4. The molten blend material is conveyed to the extrusion die, and after being extruded through the extrusion die, it is cast into a film to obtain a cast film substrate; S5. The cast substrate is subjected to biaxial stretching treatment to form a biaxially stretched film matrix. S6. Perform online double-sided synchronous pre-coating on the biaxially stretched film substrate to form an anti-UV coating on both surfaces of the film substrate. S7. Curing and shaping the UV-resistant coating to ensure it adheres to the film substrate surface; S8. The film that has been coated and cured is wound up to obtain a UV-resistant polyethylene terephthalate film.

[0005] In the above technical solution, further, in step S1: The drying temperature for polyethylene terephthalate chips is 160-170℃, and the drying time is 40-80 min; the drying temperature for UV-resistant masterbatch is 120-140℃, and the drying time is 20-40 min. The moisture content of the material after drying should be controlled below 50 ppm.

[0006] In the above technical solution, further: The masterbatch matrix of the UV-resistant masterbatch is polyethylene terephthalate.

[0007] This invention provides a production system for manufacturing UV-resistant polyethylene terephthalate (PET) films, comprising: An extruder includes a frame and a barrel mounted on the frame, with a screw installed inside the barrel and a drive mechanism to drive the screw to rotate, and a feeding hopper is provided on the side of the barrel near the drive mechanism; The feeding cylinder is mounted on the side of the frame with a bracket, and one end extends into the feeding hopper with a discharge port and the other end has a feeding port. The rotating shaft is coaxially installed inside the feeding cylinder, and the end near the feed inlet is connected to the drive motor; The spiral blades are fitted onto the rotating shaft and located inside the feeding cylinder. They are used to rotate with the rotating shaft and convey the material entering from the feed inlet to the discharge outlet. The connecting block is installed on the inner wall of the feeding hopper and is used to connect the feeding cylinder and the feeding hopper. It is rotatably connected to the end of the rotating shaft away from the drive motor. The jet mechanism is connected to the rotating shaft and is linked to the rotation of the rotating shaft. It is used to intermittently jet gas outward along the radial direction of the rotating shaft. The material shaking mechanism is installed inside the feeding hopper and is linked to the rotation of the rotating shaft to shake the material inside the feeding hopper for discharge.

[0008] In the above technical solution, further: An installation cavity is formed inside the shaft; The jet mechanism includes an inner cylinder and an air supply unit. One end of the inner cylinder is connected to the connecting block, and the other end extends into the mounting cavity and is rotatably connected to the inner wall of the mounting cavity. A through hole is provided on the connecting block, and a connector is provided connected to the through hole. The connector is connected to the air supply unit through a conduit. The inner wall of the inner cylinder has multiple first air outlets that extend radially through it, and the inner wall of the mounting cavity has multiple second air outlets that extend radially through it. When the shaft rotates, the second air outlets intermittently align with and communicate with the first air outlets.

[0009] In the above technical solution, further: The helical blades form multiple helical grooves along the axis of rotation; The first air outlet on the inner cylinder and the second air outlet on the rotating shaft are both spirally distributed and are set in correspondence with the spiral groove.

[0010] In the above technical solution, further: The spiral groove is equipped with a stirring rod that connects to the spiral blades, and the stirring rod is located on the side of the spiral blades away from the axis of rotation.

[0011] In the above technical solution, further; An annular protrusion is formed on the inner wall of the feeding hopper and is located below the discharge port of the feeding cylinder; The organizations that leak information include: The discharge hopper is installed inside the feed hopper and includes a discharge cylinder, a guide section and an extension section, with the extension section corresponding to the annular boss. A spring is mounted on an annular boss, and multiple springs are provided at equal intervals along the circumference, with the extension abutting against the top of the spring. A drive unit, mounted on an annular boss, is used to intermittently pull the extension closer to the annular boss.

[0012] In the above technical solution, further: The annular boss has multiple mounting holes for installing springs; The driving components include: An electromagnet body is installed in a mounting hole, and a spring is sleeved on the electromagnet body; A ferromagnetic body is installed on the side of the extension near the annular boss, and the end of the spring near the extension is sleeved on the ferromagnetic body. The opening and closing element is installed on the rotating shaft and is used to intermittently link with the rotation of the rotating shaft and intermittently conduct the electromagnet.

[0013] In the above technical solution, the opening and closing components further include: The first electrode block is installed on the inner wall of the equipment cavity; The second electrode block is installed on the inner wall of the equipment cavity and is correspondingly arranged with the first electrode block, forming a gap between them. A conductive sheet is mounted on the surface of the rotating shaft and is configured to correspond to the gap between the first electrode block and the second electrode block.

[0014] The beneficial effects of this invention are as follows: 1. By melt-blending UV-resistant masterbatch with PET chips, the film substrate itself acquires UV resistance. Then, an UV-resistant coating is formed on both sides of the film substrate through online double-sided synchronous pre-coating, achieving dual UV protection for both the substrate and the coating. Online double-sided coating eliminates offline transfer and secondary processing steps, simplifying the production process and improving production efficiency. Simultaneous double-sided coating preparation helps alleviate stress differences between the two sides of the film, reduces the risk of film warping, and improves the overall performance of the finished film.

[0015] 2. By using spiral blades for stable feeding, and working in conjunction with the intermittent jetting mechanism and the material shaking mechanism, material bridging, clumping, and blockage can be effectively eliminated, avoiding material shortages and supply fluctuations during the extrusion process. This ensures uniform and stable material conveying, effectively improves the uniformity of melt blending, guarantees film quality from the source, and reduces product defect rates. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is the present invention. Figure 1 Top view; Figure 3 This is the present invention. Figure 2 Sectional view at point AA; Figure 4 This is the present invention. Figure 3 Enlarged view of point B in the middle; Figure 5 This is the present invention. Figure 3 Enlarged view of point C in the middle; Figure 6 This is a partial structural diagram of the helical blade of the present invention; The markings in the diagram represent: 1. Frame; 2. Cylinder; 3. Drive mechanism; 4. Feed hopper; 40. Annular boss; 41. Mounting hole; 5. Feeding cylinder; 50. Discharge port; 51. Feed inlet; 6. Support; 7. Rotating shaft; 8. Drive motor; 9. Spiral blade; 10. Connecting block; 11. Air jet mechanism; 110. Inner cylinder; 111. Through hole; 112. Connector; 113. First air outlet; 114. Second air outlet; 12. Shaking mechanism; 120. Discharge hopper; 1200. Discharge cylinder; 1201. Guide section; 1202. Extension section; 121. Spring; 122. Electromagnet; 123. Ferromagnetic body; 124. First electrode block; 125. Second electrode block; 126. Conductive sheet; 13. Mounting cavity; 14. Spiral groove; 15. Stirring rod; 16. Partition plate; 17. Equipment cavity. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0018] Example 1:

[0019] This embodiment provides a process for producing UV-resistant polyethylene terephthalate (PET) film, including the following steps: S1. Take polyethylene terephthalate chips and UV-resistant masterbatch according to the preset ratio, and dry the polyethylene terephthalate chips and UV-resistant masterbatch respectively. S2. The dried polyethylene terephthalate chips are mixed with the UV-resistant masterbatch, and the mixture is then fed into a twin-screw extruder. S3. The mixed polyethylene terephthalate chips and UV-resistant masterbatch are melt-blended using a twin-screw extruder to obtain a melt-blended material. S4. The molten blend material is conveyed to the extrusion die, and after being extruded through the extrusion die, it is cast into a film to obtain a cast film substrate; S5. The cast substrate is subjected to biaxial stretching treatment to form a biaxially stretched film matrix. S6. Perform online double-sided synchronous pre-coating on the biaxially stretched film substrate to form an anti-UV coating on both surfaces of the film substrate. S7. Curing and shaping the UV-resistant coating to ensure it adheres to the film substrate surface; S8. The film that has been coated and cured is wound up to obtain a UV-resistant polyethylene terephthalate film.

[0020] As can be seen from this embodiment, by melt-blending the UV-resistant masterbatch with PET chips, the film substrate itself acquires UV resistance. Then, by online double-sided synchronous pre-coating, a UV-resistant coating is formed on both sides of the film substrate, achieving dual UV protection of the substrate and the coating. Online double-sided coating eliminates offline transfer and secondary processing steps, simplifies the production process, and improves production efficiency. Simultaneous double-sided coating preparation helps to alleviate stress differences on both sides of the film, reduces the risk of film warping, and improves the overall performance of the finished film.

[0021] Example 2:

[0022] This embodiment provides a process for producing a UV-resistant polyethylene terephthalate film. In addition to the technical solutions described in the above embodiments, it also has the following technical features, in step S1: The drying temperature for polyethylene terephthalate chips is 160-170℃, and the drying time is 40-80 min; the drying temperature for UV-resistant masterbatch is 120-140℃, and the drying time is 20-40 min. The moisture content of the material after drying should be controlled below 50 ppm.

[0023] As can be seen from this embodiment, by using appropriate drying process conditions for PET chips and UV-resistant masterbatch respectively, the internal moisture of the materials can be fully removed, the moisture content can be controlled within a reasonable range, the hydrolysis and degradation phenomenon during melt extrusion can be reduced, defects such as bubbles and crystal points in the film can be avoided, and the extrusion film quality and mechanical properties of the film can be guaranteed.

[0024] Example 3:

[0025] This embodiment provides a process for producing UV-resistant polyethylene terephthalate (PET) films. In addition to the technical solutions described in the above embodiments, it also has the following technical features: The masterbatch matrix of the UV-resistant masterbatch is polyethylene terephthalate.

[0026] As can be seen from this embodiment, by using the same material as the PET chip substrate for the UV-resistant masterbatch matrix, the compatibility between the UV-resistant masterbatch and the PET chips is improved, the dispersion during the melt blending process is more uniform, the phase separation phenomenon is reduced, and the functional components of the masterbatch are evenly distributed inside the film matrix, ensuring the uniform and stable UV resistance of the film as a whole, while improving the film formation effect.

[0027] Example 4:

[0028] This embodiment provides a production system for manufacturing UV-resistant polyethylene terephthalate (PET) films, including: An extruder includes a frame 1 and a barrel 2 mounted on the frame 1. A screw is installed inside the barrel 2, and a drive mechanism 3 is provided to drive the screw to rotate. A feeding hopper 4 is provided on the side of the barrel 2 near the drive mechanism 3. The feeding cylinder 5 is mounted on the side of the frame 1 by means of a bracket 6, and one end extends into the feeding hopper 4 with a discharge port 50 and the other end has a feed port 51. The rotating shaft 7 is coaxially installed inside the feeding cylinder 5, and the end near the feed inlet 51 is connected to the drive motor 8; The spiral blade 9 is sleeved on the rotating shaft 7 and located inside the feeding cylinder 5. It is used to rotate with the rotating shaft 7 and to convey the material entering from the feed port 51 to the discharge port 50. The connecting block 10 is installed on the inner wall of the feeding hopper 4 and is used to connect the feeding cylinder 5 and the feeding hopper 4. It is also rotatably connected to the end of the rotating shaft 7 away from the drive motor 8. The jet mechanism 11 is connected to the rotating shaft 7 and is linked to the rotation of the rotating shaft 7. It is used to intermittently jet gas outward along the radial direction of the rotating shaft 7. The material shaking mechanism 12 is installed in the feeding hopper 4 and is linked to the rotation of the rotating shaft 7 to shake the material in the feeding hopper 4 for discharge. The spiral blade 9 and the rotating shaft 7 can be welded together, and a feed hopper or a feed chute is installed at the feed inlet 51. The specific structure of the drive mechanism 3 and the screw, as well as other mechanisms of the extruder, such as the barrel 2 heating and cooling unit, control unit, and extrusion die assembly, are all conventional structures of traditional screw extruders, which are known to those skilled in the art from traditional screw extruders and will not be described in detail here.

[0029] As can be seen from this embodiment, by using the rotating shaft 7 to drive the spiral blade 9 to rotate, the mixed material can be continuously and stably fed, reducing the instantaneous excessive material caused by directly adding the mixed material to the upper hopper 4, which may lead to material bridging, clumping, or even material blockage, as well as material shortage at the extrusion die, thus effectively ensuring the film melt blending effect and product quality. The jetting mechanism 11 can blow the material, which can not only reduce material jamming, but also introduce dry and high-temperature gas to further dry and preheat the material, ensuring the stability and quality of subsequent film formation. The shaking mechanism 12 can further prevent bridging, clumping and blockage of material from the feeding hopper 4. By shaking the material, it ensures smooth and stable discharge.

[0030] Example 5:

[0031] This embodiment provides a production system for manufacturing UV-resistant polyethylene terephthalate (PET) films. In addition to the technical solutions described in the above embodiments, it also has the following technical features: The rotating shaft 7 has an internal mounting cavity 13; The jet mechanism 11 includes an inner cylinder 110 and an air supply unit. One end of the inner cylinder 110 is connected to the connecting block 10, and the other end extends into the mounting cavity 13 and is rotatably connected to the inner wall of the mounting cavity 13. A through hole 111 is provided on the connecting block 10, and a connector 112 is provided connected to the through hole 111. The connector 112 is connected to the air supply unit through a conduit. The inner wall of the inner cylinder 110 is provided with a plurality of first air outlet holes 113 through the radial direction, and the inner wall of the mounting cavity 13 is provided with a plurality of second air outlet holes 114 through the radial direction. When the rotating shaft 7 rotates, the second air outlet holes 114 are intermittently aligned with the first air outlet holes 113 and connected. Meanwhile, the gas supply unit can be an air compressor, air tank, dryer, electric heater, etc., which are conventional equipment used to supply dry, high-pressure, and high-temperature gases. These are choices that those skilled in the art can make according to their needs, and will not be elaborated here. It should be noted that the dry, high-pressure, high-temperature gas has a water content of less than or equal to 30 ppm, a gas supply pressure of 0.25-0.4 MPa, and a gas temperature of 70-90℃.

[0032] As can be seen from this embodiment, the gas supply unit supplies dry, high-pressure, and high-temperature gas to the inner cylinder 110, preventing the material from absorbing moisture again due to the air jet, thus ensuring the quality of subsequent products. At the same time, the air pressure impact is moderate, which can effectively loosen the material without causing excessive material to be thrown up, and the gas temperature can have a heat preservation and preheating effect on the material. The first air outlet 113 opened on the inner wall of the inner cylinder 110 and the second air outlet 114 opened on the inner wall of the mounting cavity 13 can be fixed by the inner cylinder 110. When the rotating shaft 7 rotates, the first air outlet 113 and the second air outlet 114 are intermittently connected, thereby realizing intermittent air jet and reducing the accumulation and jamming of material when it is conveyed by the spiral blade 9.

[0033] Example 6:

[0034] This embodiment provides a production system for manufacturing UV-resistant polyethylene terephthalate (PET) films. In addition to the technical solutions described in the above embodiments, it also has the following technical features: The spiral blade 9 forms multiple spiral grooves 14 along the axis of rotation 7; The first air outlet 113 on the inner cylinder 110 and the second air outlet 114 on the rotating shaft 7 are both spirally distributed and are corresponding to the spiral groove 14.

[0035] As can be seen from this embodiment, by correspondingly setting the first air outlet 113 and the second air outlet 114 with the multiple spiral grooves 14 formed by the spiral blade 9 along the axis of the rotating shaft 7, it is possible to alleviate the material accumulation and jamming that may occur at the spiral grooves 14.

[0036] Example 7:

[0037] This embodiment provides a production system for manufacturing UV-resistant polyethylene terephthalate (PET) films. In addition to the technical solutions described in the above embodiments, it also has the following technical features: The spiral groove 14 is provided with a stirring rod 15 that connects to the spiral blade 9, and the stirring rod 15 is located on the side of the spiral blade 9 away from the axis of the rotating shaft 7.

[0038] As can be seen from this embodiment, by setting the stirring rod 15, the material can be turned over to a certain extent during the rotation of the spiral blade 9, which promotes the mixing of the material and prevents stratification.

[0039] Example 8:

[0040] This embodiment provides a production system for producing UV-resistant polyethylene terephthalate film, which, in addition to the technical solutions of the above embodiments, also has the following technical features; An annular protrusion 40 is formed on the inner wall of the feeding hopper 4 and is located below the discharge port 50 of the feeding cylinder 5; The 12 information-sharing agencies include: The discharge hopper 120 is installed inside the feed hopper 4 and includes a discharge cylinder 1200, a guide part 1201 and an extension part 1202, and the extension part 1202 is correspondingly provided with the annular boss 40. Spring 121 is mounted on an annular boss 40 and has multiple protrusions at equal intervals along the circumference, and the extension 1202 abuts against the top of spring 121. A drive unit, mounted on the annular boss 40, is used to intermittently pull the extension 1202 close to the annular boss 40. The force exerted by the driving component on the discharge hopper 120 is greater than the elastic restoring force of the spring 121. The elastic restoring force of the spring 121 is greater than the total weight of the discharge hopper 120 and the material. The weight of the material can reduce the rotation speed of the spiral blade 9, thereby reducing the feeding speed of the discharge port 50, and thus making the total weight of the discharge hopper 120 and the material less than the elastic restoring force of the spring 121.

[0041] As can be seen from this embodiment, by using a discharge hopper 120 for the shaking mechanism 12 and supporting it with a spring 121, the discharge hopper 120 can vibrate continuously. Furthermore, the driving component applies force to the discharge hopper 120 intermittently, which avoids the inability to compress the spring 121 and produce a vibration effect when there is a small amount of material. This is beneficial for the discharge hopper 120 to vibrate and discharge material continuously, reducing the possibility of material jamming.

[0042] Example 9:

[0043] This embodiment provides a production system for manufacturing UV-resistant polyethylene terephthalate (PET) films. In addition to the technical solutions described in the above embodiments, it also has the following technical features: The annular boss 40 has multiple mounting holes 41 for mounting springs 121; The driving components include: An electromagnet body 122 is installed in the mounting hole 41, and a spring 121 is sleeved on the electromagnet body 122. Ferromagnetic body 123 is installed on the side of extension 1202 near the annular boss 40, and spring 121 is sleeved on the end of extension 1202 near ferromagnetic body 123. The opening and closing component is installed on the rotating shaft 7 and is used to intermittently link with the rotation of the rotating shaft 7 and intermittently conduct the electromagnet body 122. Among them, the feeding cylinder 5 is provided with a partition 16 on the side near the connecting block 10, and the partition 16 and the connecting block 10 form a device cavity 17 for installing opening and closing parts. Meanwhile, the spring 121 can be made of austenitic stainless steel to avoid affecting the attraction of the electromagnet 122 to the ferromagnet 123.

[0044] As can be seen from this embodiment, by opening the mounting hole 41, the installation stability of the spring 121 is improved, and the multiple electromagnets 122 are switched on and off by the opening and closing device. Then, based on the intermittent adsorption of the electromagnets 122 on the ferromagnets 123, the continuous action on the discharge hopper 120 is ensured, and the continuous shaking of the discharge hopper 120 is maintained. The spring 121 is sleeved on the electromagnet body 122, and the mounting hole 41 can limit the installation of the spring 121. At the same time, the end of the spring 121 is also sleeved on the ferromagnet body 123. Thus, the stability of the spring 121 installation can be further improved by installing the electromagnet body 122 and the ferromagnet body 123. Meanwhile, the opening and closing components are arranged in an independent equipment cavity 17, which is isolated from the materials, reducing the interference of material dust on the opening and closing components.

[0045] Example 10:

[0046] This embodiment provides a production system for manufacturing UV-resistant polyethylene terephthalate (PET) films. In addition to the technical solutions described in the above embodiments, it also has the following technical features, including an opening / closing component: The first electrode block 124 is installed on the inner wall of the equipment cavity 17; The second electrode block 125 is installed on the inner wall of the equipment cavity 17 and is correspondingly arranged with the first electrode block 124, forming a gap between them. The conductive sheet 126 is mounted on the surface of the rotating shaft 7 and is configured to correspond to the gap between the first electrode block 124 and the second electrode block 125. The first electrode block 124 and the second electrode block 125 are connected in series in the circuit of the electromagnet body 122. The specific circuit wiring is existing conventional technology, which can be known by those skilled in the art from traditional circuit wiring, and will not be described in detail here.

[0047] As can be seen from this embodiment, by setting the driving component as a first electrode block 124 and a second electrode block 125, and having the conductive sheet 126 follow the rotation of the rotating shaft 7, when the conductive sheet 126 enters the gap, the first electrode block 124 and the second electrode block 125 are energized, thereby realizing the energization of the electromagnet 122. When the conductive sheet 126 moves out of the gap, the first electrode block 124 and the second electrode block 125 are de-energized, thereby realizing the de-energization of the electromagnet 122. The intermittent energization and de-energization of the electromagnet 122 following the rotation of the rotating shaft 7 ensures the continuous shaking of the discharge hopper 120.

[0048] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A process for producing UV-resistant polyethylene terephthalate film, characterized in that, Includes the following steps: S1. Take polyethylene terephthalate chips and UV-resistant masterbatch according to the preset ratio, and dry the polyethylene terephthalate chips and UV-resistant masterbatch respectively. S2. The dried polyethylene terephthalate chips are mixed with the UV-resistant masterbatch, and the mixture is then fed into a twin-screw extruder. S3. The mixed polyethylene terephthalate chips and UV-resistant masterbatch are melt-blended using a twin-screw extruder to obtain a melt-blended material. S4. The molten blend material is conveyed to the extrusion die, and after being extruded through the extrusion die, it is cast into a casting sheet to obtain a casting substrate. S5. The cast substrate is subjected to biaxial stretching treatment to form a biaxially stretched film substrate. S6. Perform online double-sided synchronous pre-coating on the biaxially stretched film substrate to form an anti-UV coating on both surfaces of the film substrate. S7. The UV-resistant coating is cured and shaped to solidify and adhere to the surface of the film substrate. S8. The film that has been coated and cured is wound up to obtain a UV-resistant polyethylene terephthalate film.

2. The process for producing UV-resistant polyethylene terephthalate film according to claim 1, characterized in that, In step S1: The polyethylene terephthalate chips are dried at a temperature of 160-170℃ for 40-80 minutes; the UV-resistant masterbatch is dried at a temperature of 120-140℃ for 20-40 minutes, and the moisture content of the dried material is controlled below 50 ppm.

3. The process for producing UV-resistant polyethylene terephthalate film according to claim 1, characterized in that: The masterbatch matrix of the UV-resistant masterbatch is polyethylene terephthalate.

4. A production system applied to the production process of the UV-resistant polyethylene terephthalate film according to any one of claims 1-3, characterized in that, include: An extruder includes a frame (1) and a barrel (2) mounted on the frame (1). A screw is installed inside the barrel (2) and a drive mechanism (3) is provided to drive the screw to rotate. A feeding hopper (4) is provided on the side of the barrel (2) near the drive mechanism (3). The feeding cylinder (5) is installed on the side of the frame (1) by means of a bracket (6), and one end extends into the feeding hopper (4) with a discharge port (50) and the other end has a feed port (51). The rotating shaft (7) is coaxially installed inside the feed cylinder (5), and the end near the feed inlet (51) is connected to the drive motor (8). The spiral blade (9) is sleeved on the rotating shaft (7) and located inside the feed cylinder (5). It is used to rotate with the rotating shaft (7) and to convey the material entering from the feed inlet (51) to the discharge outlet (50). The connecting block (10) is installed on the inner wall of the feeding hopper (4) for connecting the feeding cylinder (5) and the feeding hopper (4), and is rotatably connected to the end of the rotating shaft (7) away from the drive motor (8); The jet mechanism (11) is connected to the rotating shaft (7) and is linked to the rotation of the rotating shaft (7) for intermittent jetting outward along the radial direction of the rotating shaft (7); The material shaking mechanism (12) is installed in the feeding hopper (4) and is linked with the rotation of the rotating shaft (7) to shake the material in the feeding hopper (4) for discharge.

5. The production system for producing UV-resistant polyethylene terephthalate film according to claim 4, characterized in that: The rotating shaft (7) has an internal mounting cavity (13). The jet mechanism (11) includes an inner cylinder (110) and an air supply unit. One end of the inner cylinder (110) is connected to the connecting block (10), and the other end extends into the mounting cavity (13) and is rotatably connected to the inner wall of the mounting cavity (13). A through hole (111) is provided on the connecting block (10), and a connector (112) is provided connected to the through hole (111). The connector (112) is connected to the air supply unit through a conduit. The inner wall of the inner cylinder (110) is provided with a plurality of first air outlet holes (113) through the radial direction, and the inner wall of the mounting cavity (13) is provided with a plurality of second air outlet holes (114) through the radial direction. When the rotating shaft (7) rotates, the second air outlet holes (114) are intermittently aligned with the first air outlet holes (113) and connected.

6. The production system for producing UV-resistant polyethylene terephthalate film according to claim 5, characterized in that: The spiral blade (9) forms multiple spiral grooves (14) along the axis of rotation (7); The first air outlet (113) is located on the inner cylinder (110) and the second air outlet (114) is located on the rotating shaft (7) in a spiral pattern, and both are set in correspondence with the spiral groove (14).

7. The production system for producing UV-resistant polyethylene terephthalate film according to claim 6, characterized in that: The spiral groove (14) is provided with a stirring rod (15) that connects to the spiral blade (9), and the stirring rod (15) is located on the side of the spiral blade (9) away from the axis of rotation (7).

8. The production system for the UV-resistant polyethylene terephthalate film production process according to claim 4, characterized in that... ； The inner wall of the feeding hopper (4) forms an annular boss (40), which is located below the discharge port (50) of the feeding cylinder (5); The shaking mechanism (12) includes: The discharge hopper (120) is installed inside the feed hopper (4) and includes a discharge cylinder (1200), a guide part (1201) and an extension part (1202), and the extension part (1202) is correspondingly provided with the annular boss (40); Spring (121) is mounted on an annular boss (40) and multiple such bosses are provided at equal intervals along the circumference, and the extension (1202) abuts against the top of the spring (121); A drive unit, mounted on an annular boss (40), is used to intermittently pull the extension (1202) close to the annular boss (40).

9. The production system for the UV-resistant polyethylene terephthalate film production process according to claim 8, characterized in that: The annular boss (40) has multiple mounting holes (41) for mounting springs (121). The driving component includes: An electromagnet body (122) is installed in a mounting hole (41), and a spring (121) is sleeved on the electromagnet body (122). A ferromagnetic body (123) is installed on the side of the extension (1202) near the annular boss (40), and a spring (121) is sleeved on the end of the extension (1202) near the ferromagnetic body (123). The opening and closing component is installed on the rotating shaft (7) and is used to intermittently link with the rotation of the rotating shaft (7) and intermittently conduct the electromagnet (122). The feeding cylinder (5) has a partition (16) on the side near the connecting block (10), and a device cavity (17) for installing opening and closing parts is formed between the partition (16) and the connecting block (10).

10. The production system for the UV-resistant polyethylene terephthalate film production process according to claim 9, characterized in that, The opening and closing element includes: The first electrode block (124) is installed on the inner wall of the equipment cavity (17); The second electrode block (125) is installed on the inner wall of the equipment cavity (17) and is correspondingly arranged with the first electrode block (124), forming a gap between them; A conductive sheet (126) is mounted on the surface of the rotating shaft (7) and is configured to correspond to the gap between the first electrode block (124) and the second electrode block (125).

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