A production process for reducing the heat shrinkage of a film

Abstract

The present application relates to the technical field of PVDC casing film production process, and particularly relates to a production process for reducing the heat shrinkage of a film, which comprises a pretreatment unit, a roller unit and a setting unit. First, in the pretreatment unit, a film roll is loaded on a fixing roller, which is used to fix the film roll to prevent the film roll from swinging and moving after starting; the fixing roller is made of metal and is fixed on a rack through connecting rods at both ends; after passing through the fixing roller, the film roll is flattened by a metal flattening straight roller, which is connected to a bearing seat through a bearing. The present application can improve the production process and innovatively modify three production devices, thereby maximizing the improvement of the heat shrinkage performance of the PVDC casing film, improving the utilization rate of the film and reducing the occurrence rate of defective and unqualified products.

Description

Technical Field

[0001] This invention relates to the technical field of PVDC sausage casing film production process, specifically to a production process for reducing the thermal shrinkage rate of the film. Background Technology

[0002] PVDC, as a green and novel packaging material, can be widely used in high-end packaging fields such as food, pharmaceuticals, cosmetics, military, chemicals, and hardware machinery products. It is an ideal packaging material with high barrier properties, strong toughness, and good chemical stability. However, PVDC casing film is a heat-sensitive flexible packaging material with a high heat shrinkage rate, which will shrink at high temperatures. The heat shrinkage rate of plastic film is related to the shape and dimensional accuracy of the product, and has a significant impact on the aesthetics of flexible packaging. An appropriate heat shrinkage rate can make the packaging compact, especially a uniform longitudinal and transverse shrinkage rate, which can make the film have a tighter and more uniform wrapping effect, preventing wrinkles on the packaging cover caused by uneven shrinkage. During the production of PVDC sausage casing film, due to its thinner and softer film rolls and larger shrinkage rate compared to general packaging films, the film thickness may be uneven, sometimes too thick, sometimes too thin, or the film surface may be uneven due to various reasons such as raw materials, machinery, and operation. Usually, measures and means such as adjusting resin raw materials, adjusting die head gap and temperature, and adjusting blow-up ratio and traction ratio are used to improve the blow molding process and stabilize production. However, the above processes inevitably have the possibility of quality accidents, which leads to the problem of unstable film heat shrinkage rate in subsequent production processes. Summary of the Invention

[0003] The purpose of this invention is to provide a production process for reducing the thermal shrinkage rate of film. This process, through improvements in the production process and innovative modifications to three production equipment, maximizes the improvement of the thermal shrinkage performance of PVDC sausage casing film, increases film utilization, and reduces the incidence of defective and substandard products.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A production process for reducing the thermal shrinkage rate of films mainly includes the following steps: S1. The entire process consists of three parts: pretreatment unit, roller passing unit, and quality control unit. First, in the pretreatment unit, the film roll is loaded onto the fixed roller. The fixed roller is used to fix the film roll and prevent it from swinging or moving after the machine is started. The fixed roller is made of metal and is fixed to the frame at both ends by connecting rods. S2. After passing through the fixed roller, the film roll is flattened by the metal flattening roller. The metal flattening roller is connected to the bearing seat through the bearing, and the bearing seat is installed on the frame by the anchor bolts. The surface of the metal flattening roller can rotate 360 ​​degrees independently and flexibly. S3. After the film roll is flattened by the metal flattening straight roller, it passes through three sets of roller passing devices in sequence to stretch the film roll. The specifications of these three sets of roller passing devices are the same as those of the metal flattening straight roller in the previous process. Both ends are fixed by connecting rods, which are directly welded to the frame. During normal operation, the roller surface can move flexibly in the axial tangential direction. S4. After the film roll passes through the three sets of rollers in the previous step in sequence, it enters the low-temperature heating roller. The low-temperature heating roller is designed to heat at 30°C. The heating method of the low-temperature heating roller is oil heating. The heat transfer oil is heated by an electric heating heat transfer oil furnace and then enters from one end of the low-temperature heating roller through the oil inlet pipe. Then it flows out from the other end of the low-temperature heating roller and returns to the heating furnace through the oil outlet pipe for recirculation and heating. S5. After the film roll passes through the low-temperature heating roller, it passes through a set of guide rollers in sequence. The specifications of the guide rollers are the same as those of the low-temperature heating rollers in the previous process. The two ends of the guide rollers are fixed by connecting rods, which are directly welded to the frame. During normal operation, the roller surface of the guide rollers can move flexibly in the axial tangential direction. The function of the guide rollers in this step is to stretch the film roll. S6. After the film roll passes through the roller in the previous step, it enters the roller unit in sequence and passes through the rubber-coated arc-shaped flattening roller. The rubber-coated arc-shaped flattening roller is connected to the connecting rod through the bearing. The rubber-coated arc-shaped flattening roller can rotate 360 ​​degrees independently and flexibly. S7. After passing through the adhesive-coated arc-shaped flattening roller in the previous step, the film roll passes through three sets of rollers in sequence. The specifications of the rollers in this step are the same as those of the adhesive-coated arc-shaped flattening roller in the previous process. Both ends of the rollers are fixed by connecting rods, which are directly welded to the frame. During normal operation, the roller surface of the rollers in this step can move flexibly in the axial tangential direction. S8. After passing through the roller unit in the previous step, the film roll enters the shaping unit. First, it passes through two sets of rollers in sequence. The specifications of the two sets of rollers in this step are the same as those of the rollers in the previous process. Both ends are fixed by connecting rods, which are directly welded to the frame. During normal operation, the roller surface in this step can move flexibly in the axial tangential direction. S9. Sequentially, the film roll that has passed through the previous process enters the high-temperature heating roller of the qualitative unit. The heating temperature of the roller surface of the high-temperature heating roller is 80℃~90℃. The heating method of the high-temperature heating roller is oil heating. The heat transfer oil is heated by an electric heating heat transfer oil furnace and then enters from one end of the high-temperature heating roller through the oil inlet pipe. Then it flows out from the other end and returns to the heating furnace through the oil outlet pipe for circulation heating and reuse. S10. Sequentially, the film roll from the previous process enters the low-temperature flattening roller made of metal in the shaping unit. The heating temperature of the low-temperature flattening roller in this step is 50±1℃. The design curvature of the roller surface and the contact surface between the low-temperature flattening roller and the film roll is 50-60mm / m. The heating method of the low-temperature flattening roller in this step is oil heating. The heat transfer oil is heated by an electric heating heat transfer oil furnace and then enters from one end of the low-temperature flattening roller through the oil inlet pipe. Then it flows out from the other end and returns to the heating furnace through the oil outlet pipe for recirculation and heating. S11. After passing through a set of pressure rollers, the film roll from the previous process begins to be wound up. The effective diameter of the winding roller is 203.2mm. Both ends are connected and fixed to the robotic arm via connecting rods. The winding roller in this step uses a large core paper tube for winding, which makes the film less prone to wrinkling and the surface smoother. The film roll has better thermal stability in the subsequent curing process. S12. After passing through the winding rollers in sequence, the film roll is placed in a 60°C curing chamber for curing for 48 hours, after which the film roll is taken out.

[0005] Furthermore, in step S2, the metal flattening roller can move independently in its axial tangential direction. The movement mode is independent. Connecting rods are arranged on both sides of the metal flattening roller. After the connecting rods are properly adjusted, they are fixed. The connecting rods in this step do not move with the movement of the flattening roller surface of the metal flattening roller. Both ends of the metal flattening roller bearing seats have anchor bolts and are fixed to the equipment support by the anchor bolts.

[0006] Furthermore, in step S2, since the heating temperature of the low-temperature heating roller is 30°C and the running speed is 120-140 r / min, when a film with a thickness of 40-50 μm passes through the low-temperature heating roller, it is easy to curl and wrinkle, thus affecting the shrinkage rate of the film. Therefore, this set of metal flattening rollers is added to the upstream process. The metal flattening rollers can make the film roll have better extensibility and tensile strength before passing through the low-temperature heating roller, which is more conducive to reducing the thermal shrinkage rate of the film.

[0007] Furthermore, in step S6, the rubber-coated arc-shaped flattening roller is connected to the connecting rod via a bearing. The flattening roller in the rubber-coated arc-shaped flattening roller can move independently in the axial tangential direction. Its movement mode is independent. The connecting rod in the rubber-coated arc-shaped flattening roller is fixed after being properly adjusted in position and does not move with the movement of the flattening roller surface. The connecting rod in this step is made of metal and its curvature is fixed.

[0008] Furthermore, in step S6, one end of the connecting rod in the rubber-surfaced arc-shaped flattening roller is connected to the bending roller adjustment seat at the adjustment end via a bearing sleeve, and the other end of the connecting rod is connected to the bending roller adjustment seat at the fixed end via a bearing sleeve; the connecting rod is tightly engaged with the gear sleeve via a fixed key, and during the adjustment process, the rotation of the lead screw can be controlled by the adjustment handle to drive the gear sleeve to rotate, thereby driving the connecting rod to rotate 360 ​​degrees in the axial tangential direction.

[0009] Furthermore, in step S6, the film roll comes into contact with the curved flattening roller during its travel. The change in the rotation angle of the connecting rod will cause a change in the angle between the flattening roller and the film roll contact surface. The amount of adjustment of the arc size is 0-70 mm / m. When the arc of the contact surface between the curved flattening roller and the film roll is controlled at 50-70 mm / m, the thermal shrinkage rate of the film can be reduced to the greatest extent.

[0010] Furthermore, in step S10, connecting rods are arranged on both sides of the low-temperature flattening roller. The low-temperature flattening roller is connected to the connecting rods through bearings. The arc-shaped flattening roller surface of the low-temperature flattening roller can rotate 360 ​​degrees independently and flexibly. After the connecting rods are properly adjusted, they are fixed and do not move with the movement of the arc-shaped flattening roller surface.

[0011] Furthermore, in step S10, one end of the connecting rod in the low-temperature flattening roller is connected to the bending roller adjustment seat at the adjustment end via a bearing sleeve, and the other end of the connecting rod is connected to the bending roller adjustment seat at the fixed end via a bearing sleeve; the connecting rod is tightly engaged with the gear sleeve via a fixed key; during the adjustment process, the rotation of the lead screw is controlled by the adjustment handle to drive the gear sleeve to rotate, thereby driving the connecting rod to rotate 360 ​​degrees in the axial tangential direction.

[0012] Furthermore, in step S10, the film roll comes into contact with the arc-shaped flattening roller in the low-temperature flattening roller during its travel. The change in the rotation angle of the connecting rod will cause a change in the angle between the flattening roller and the film roll contact surface. The amount of adjustment of the arc size is 0-70 mm / m. When the arc of the contact surface between the bending roller and the film roll is controlled at 50-60 mm / m, the thermal shrinkage rate of the film can be reduced to the greatest extent.

[0013] The beneficial effects of this invention are as follows: The production process for reducing the thermal shrinkage rate of films according to this invention has a scientifically designed overall structure and layout, and compared with the existing PVDC sausage casing film production process, it has the following technical features and advantages: 1. Cost reduction and efficiency improvement: The production process of the present invention for reducing the thermal shrinkage rate of film can stabilize the thermal shrinkage rate of film to the greatest extent, improve the yield, reduce the scrap rate, and reduce the consumption of raw materials. 2. Improve production efficiency; The production process of this invention, which reduces the thermal shrinkage rate of the film, can improve the film performance, stabilize output, and significantly increase production efficiency. 3. The modified and newly added equipment occupies little space, is easy and quick to operate, is conducive to production personnel, reduces the workload of employees, and improves work efficiency; 4. The metal roller surface material used in the production process of reducing film heat shrinkage rate of the present invention has a low replacement frequency, which extends the service life of the low temperature flattening roller and reduces the frequency of equipment replacement. Attached Figure Description

[0014] Figure 1 This is an overall schematic diagram of the production process for reducing the thermal shrinkage rate of the film according to the present invention; Figure 2 This is a schematic diagram of the pretreatment unit in the production process of this invention; Figure 3 This is a schematic diagram of the roller passing unit in the production process of this invention; Figure 4 This is a schematic diagram of the structure of the qualitative unit in the production process of this invention; Figure 5 This is a schematic diagram of the flattening roller in the production process of this invention; Figure 6 This is a schematic diagram of the structure of the rubber-surfaced arc-shaped flattening roller in the production process of this invention; Figure 7 This is a schematic diagram of the structure of the bending roller adjustment end in the production process of this invention; Figure 8 This is a schematic diagram of the low-temperature flattening roller in the production process of this invention; The numbers in the diagram are as follows: 2-1-Fixed roller; 2-2-Metal flattening roller; 2-3-Passing roller A; 2-4-Passing roller B; 2-5-Passing roller C; 2-6-Low-temperature heating roller; 2-7-Passing roller D; 3-8-Rubber-surface curved flattening roller; 3-9-Passing roller E; 3-10-Passing roller F; 3-11-Passing roller G; 4-12-Passing roller H; 4-13-Passing roller I; 4-14-High-temperature heating roller; 4-15-Low-temperature flattening roller; 4-16-Pressure roller; 4-17-Take-up roller; 5-1-Flattening roller ; 5-2-Bearing A with seat; 5-3-Bearing B with seat; 6-1-Roller-shaped flattening roller surface; 6-2-Bending roller adjusting seat (fixed end); 6-3-Bending roller adjusting seat (adjusting end); 6-4-Adjusting handle; 7-1-Adjusting screw; 7-2-Gear sleeve; 7-3-Fixing key; 8-1-Metal arc-shaped flattening roller; 8-2-Metal bending roller adjusting seat (fixed end); 8-3-Metal bending roller adjusting seat (adjusting end); 8-4-Metal adjusting handle; 8-5-Oil inlet pipe; 8-6-Oil outlet pipe. Detailed Implementation

[0015] Specific Embodiment 1: The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that: In the present invention, unless otherwise specified, all implementation methods and preferred implementation methods mentioned herein can be combined with each other to form new technical solutions. In the present invention, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form new technical solutions. In the present invention, unless otherwise specified, the components involved or their preferred components can be combined with each other to form new technical solutions. In the present invention, unless otherwise specified, the numerical range "a~b" represents an abbreviation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "1.5~2.5" means that all real numbers between "1.5~2.5" have been listed herein, and "1.5~2.5" is just an abbreviation of these numerical combinations. The "scope" disclosed in this invention is in the form of a lower limit and an upper limit, and may be one or more lower limits and one or more upper limits, respectively. In this invention, unless otherwise stated, the various reaction or operation steps may be performed sequentially or in sequence. Preferably, the reaction methods described herein are performed sequentially. Unless otherwise stated, the technical and scientific terms used herein have the same meaning as those familiar with the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be applied to this invention. To address the problems of unstable heat shrinkage performance, low film utilization, and high incidence of defective and substandard products in existing PVDC casing films, this invention provides a production process for reducing the heat shrinkage rate of the film, mainly including the following steps: S1. The entire process consists of three parts: pretreatment unit, roller passing unit, and quality control unit. First, in the pretreatment unit, the film roll is mounted on the fixed roller 2-1. The fixed roller is used to fix the film roll and prevent it from swinging or moving after the machine is started. The fixed roller is made of metal and is fixed to the frame at both ends by connecting rods. S2. After passing through the fixed roller, the film roll is flattened by the metal flattening roller. During installation, the metal flattening roller is connected to the bearing housing via bearings, and the bearing housing is mounted on the frame with anchor bolts. The surface of the metal flattening roller can rotate 360 ​​degrees independently; that is, the flattening roller can move independently in its axial tangential direction. Its movement is independent, while the connecting rod is fixed after being properly adjusted and does not move with the movement of the flattening roller surface. Both ends of the flattening roller bearing housing have anchor bolts, which are used to fix it to the equipment support. Since the design heating temperature of the low-temperature heating rollers 2-6 is 30℃ and the operating speed is 120-140r / min, when a film with a thickness of 40-50μm passes through the low-temperature heating roller, it is easy to curl and wrinkle, thus affecting the shrinkage rate of the film. Therefore, this set of metal flattening rollers is added to the upstream process. This set of metal flattening rollers can give the film roll better extensibility and tensile strength before passing through the low-temperature heating roller, which is more conducive to reducing the thermal shrinkage rate of the film. S3. After the film roll is flattened by the metal flattening straight roller, it passes through three sets of roller passing devices in sequence to stretch the film roll. The specifications of these three sets of roller passing devices are the same as those of the metal flattening straight roller in the previous process. Both ends are fixed by connecting rods, which are directly welded to the frame. During normal operation, the roller surface can move flexibly in the axial tangential direction. S4. After the film roll passes through the three sets of rollers in the previous step, it enters the low-temperature heating rollers 2-6. The low-temperature heating rollers are designed to heat at 30°C. The heating method of the low-temperature heating rollers is oil heating. The heat transfer oil is heated by an electric heating heat transfer oil furnace and then enters from one end of the low-temperature heating roller through the oil inlet pipe. It then flows out from the other end of the low-temperature heating roller and returns to the heating furnace through the oil outlet pipe for recirculation and heating. S5. After the film roll passes through the low-temperature heating roller, it passes through a set of guide rollers in sequence. The specifications of the guide rollers are the same as those of the low-temperature heating rollers in the previous process. The two ends of the guide rollers are fixed by connecting rods, which are directly welded to the frame. During normal operation, the roller surface of the guide rollers can move flexibly in the axial tangential direction. The function of the guide rollers in this step is to stretch the film roll. S6. After the film roll passes through the rollers in the previous step, it enters the roller unit in sequence, passing through the curved rubber-coated flattening roller 3-8. This curved rubber-coated flattening roller is connected to a connecting rod via bearings. The curved rubber-coated flattening roller surface 6-1 can rotate 360 ​​degrees independently. The curved rubber-coated flattening roller can move independently in its axial tangential direction. Its movement is independent. The connecting rod is fixed after being properly adjusted and does not move with the flattening roller surface. The connecting rod is made of metal with a fixed curvature. One end of the connecting rod is connected to the bending roller adjusting seat 6-3 at the adjusting end via a bearing sleeve, and the other end of the connecting rod is connected to the bending roller adjusting seat 6-2 at the fixed end via a bearing sleeve. The detailed structure of the bending roller adjusting seat at the adjusting end is as follows: Figure 7 As shown, the connecting rod is tightly engaged with the gear sleeve 7-2 via the fixing key 7-3. During adjustment, the rotation of the lead screw is controlled by the adjusting handle 6-4, which drives the gear sleeve to rotate, thereby causing the connecting rod to rotate 360 ​​degrees in the axial tangential direction. The internal structure of the fixed end curved roller adjusting seat is the same as that of the adjusting end, consisting of the gear sleeve and the fixing key. Both the fixed end curved roller adjusting seat and the adjusting end curved roller adjusting seat have anchor bolts, which are used to fix them to the equipment support. During adjustment, rotating the adjusting handle 6-4 will change the curvature of the flattening roller surface. Rotating the adjusting seat handle clockwise will cause the adjusting lead screw to rotate accordingly. Due to the tight engagement of the lead screw, fixing key, and gear sleeve, the connecting rod will rotate 360 ​​degrees in its axial tangential direction. As the film roll contacts the curved flattening roller during its travel, the change in the rotation angle of the connecting rod will cause a change in the angle of the contact surface between the flattening roller and the film roll. The curvature adjustment range is 0-70 mm / m, which can be flexibly applied in actual production. When the curvature of the contact surface between the bending roller and the film roll is controlled at 50-70 mm / m, the thermal shrinkage rate of the film can be reduced to the greatest extent and the effect is optimal. Rotating counterclockwise will reduce the curvature of the bending roller. S7. After passing through the adhesive-coated arc-shaped flattening roller in the previous step, the film roll passes through three sets of rollers in sequence. The specifications of the rollers in this step are the same as those of the adhesive-coated arc-shaped flattening roller in the previous process. Both ends of the rollers are fixed by connecting rods, which are directly welded to the frame. During normal operation, the roller surface of the rollers in this step can move flexibly in the axial tangential direction. S8. After passing through the roller unit in the previous step, the film roll enters the shaping unit. First, it passes through two sets of rollers in sequence. The specifications of the two sets of rollers in this step are the same as those of the rollers in the previous process. Both ends are fixed by connecting rods, which are directly welded to the frame. During normal operation, the roller surface in this step can move flexibly in the axial tangential direction. S9. Sequentially, the film roll that has passed through the previous process enters the high-temperature heating roller 4-14 of the qualitative unit. The heating temperature of the roller surface of the high-temperature heating roller is 80℃~90℃. The heating method of the high-temperature heating roller is oil heating. The heat transfer oil is heated by an electric heating heat transfer oil furnace and then enters from one end of the high-temperature heating roller through the oil inlet pipe. Then it flows out from the other end and returns to the heating furnace through the oil outlet pipe for circulation heating and reuse. S10. Sequentially, the film roll that has passed the previous process enters the low-temperature flattening rollers 4-15 made of metal in the shaping unit. The original process design here is a non-heated, straight, adhesive-coated roller. Figure 8Detailed diagram of the low-temperature flattening roller: 8-1 is the metal arc-shaped flattening roller; 8-2 is the metal bending roller adjustment seat at the fixed end; 8-3 is the metal bending roller adjustment seat at the adjustment end; 8-4 is the metal adjustment handle of the bending roller adjustment seat; 8-5 is the inlet pipe of the heat transfer oil; 8-6 is the outlet pipe of the heat transfer oil. The designed heating temperature of the low-temperature flattening roller is 50±1℃, and the designed curvature of the roller surface contacting the film roll is 50-60mm / m. The length of the low-temperature flattening roller surface is consistent with the passing length of the preceding and following processes. The low-temperature flattening roller is connected to the connecting rod via bearings. Its arc-shaped flattening roller surface can rotate 360 ​​degrees independently and flexibly, meaning the flattening roller can move independently in its axial tangential direction. The connecting rod, after being properly adjusted, is fixed and does not move with the movement of the flattening roller surface. The connecting rod is made of metal and has a fixed degree of curvature. One end of the connecting rod is connected to the fixed end metal bending roller adjusting seat 8-2 via a bearing sleeve. The detailed structure of the adjusting end bending roller adjusting seat is as follows: Figure 7 As shown, the connecting rod is tightly engaged with the gear sleeve 7-2 via the fixing key 7-3. During adjustment, the rotation of the lead screw is controlled by the metal adjusting handle 8-4, which drives the gear sleeve to rotate, thereby causing the connecting rod to rotate 360 ​​degrees in the axial tangential direction. The internal structure of the fixed end bending roller adjusting seat is the same as that of the adjusting end, both consisting of a gear sleeve and a fixing key. Both the fixed end bending roller adjusting seat and the adjusting end bending roller adjusting seat have anchor bolts, which are used to fix them to the equipment support. The heating method of this low-temperature flattening roller is oil heating. The heat transfer oil is heated by an electric heating heat transfer oil furnace and then enters from one end of the low-temperature flattening roller through the oil inlet pipe, and then flows out from the other end and returns to the heating furnace for recirculation and heating. During adjustment, rotating the metal adjusting handle 8-4 will change the curvature of the flattening roller surface. Rotating the adjusting seat handle clockwise will cause the adjusting lead screw to rotate accordingly. Due to the tight engagement of the lead screw, fixing key, and gear sleeve, the connecting rod will rotate 360 ​​degrees in its axial tangential direction. As the film roll travels through the curved flattening roller, changes in the connecting rod's rotation angle will cause changes in the angle between the flattening roller and the film roll's contact surface. The degree of adjustment for the curvature ranges from 0-70 mm / m, and can be flexibly applied in actual production. When the curvature of the contact surface between the bending roller and the film roll is controlled at 50-60 mm / m, the thermal shrinkage rate of the film can be minimized. Rotating the handle counterclockwise will reduce the curvature of the bending roller. The film rolls are rapidly shaped due to the temperature difference generated after passing through high-temperature heating rollers and low-temperature flattening rollers. This high and low temperature heating process stabilizes the thermal shrinkage rate of the film, and the curved roller design increases the lateral tensile force of the film, which is more conducive to improving the film's elongation. The use of metal rollers instead of rubber rollers solves the problem of frequent equipment replacement and short service life caused by rubber aging. S11. After passing through a set of pressure rollers 4-16, the film roll from the previous process begins to be wound up. The effective diameter of the winding roller 4-17 is 203.2mm. Both ends are connected and fixed to the robotic arm via connecting rods. The winding roller in this step uses a large core paper tube for winding, which makes the film less prone to wrinkling and the surface smoother. The film roll has better thermal stability in the subsequent curing process. S12. After passing through the winding rollers in sequence, the film roll is placed in a 60°C curing chamber for curing for 48 hours, after which the film roll is taken out.

[0016] Please refer to the above. Figure 1 , Figure 2 , Figure 5 The labeling of the flattening and straightening roller in the above case demonstrates that the addition of the flattening and straightening roller can effectively solve the problem of unstable heat shrinkage rate of the film and reduce the heat shrinkage rate of the film. Under the premise that other parameters (operators, process parameters, equipment, film type and structure, workshop temperature and humidity, etc.) remain unchanged, the addition of the flattening and straightening roller was used to measure the heat shrinkage rate of the produced film rolls. The test data results are as follows:

[0017] Through experimentation and verification, the following conclusion was reached: After adding the flattening roller, the heat shrinkage rate of the long and short sides of the film decreased by -0.4 mm and -0.2 mm respectively compared with the heat shrinkage rate without the flattening roller. The overall shrinkage rate showed a downward trend. In subsequent actual production, when other film structures were replaced, the heat shrinkage rate decreased to varying degrees. Multiple tests have proven that the addition of the flattening roller is beneficial to improving the heat shrinkage rate performance of the film. 2. Please refer to the above. Figure 1 , Figure 3 , Figure 6 Regarding the labeling of the curved flattening roller on the adhesive surface, this invention replaces the roller with a flattening bending roller to prevent film wrinkling and edge overlapping, ultimately reducing the film's heat shrinkage rate. With other parameters (operators, process parameters, equipment, film type and structure, workshop temperature and humidity, etc.) remaining unchanged, by changing this to a curved flattening bending roller, and conducting heat shrinkage rate tests on the produced film rolls at a radius of 50-70 mm / m, the test data comparison results are as follows:

[0018] Through experimental verification, the following experimental conclusions were drawn: After improving the curvature of the flattening roller to 50-70 mm / m, the film's heat shrinkage rate decreased by -0.4 mm on the long side and -0.3 mm on the short side compared to a straight roller without curvature. In subsequent production processes, when switching to other film structures, flattening rollers with a curvature of 50-70 mm / m were consistently used, resulting in varying degrees of reduction in heat shrinkage rate. This demonstrates the innovative improvement of the flattening roller, and that designing the curvature to 50-70 mm / m significantly improves and enhances the film's heat shrinkage performance. 3. Please refer to the above. Figure 1 , Figure 4 , Figure 8 Regarding the labeling of the low-temperature flattening roller, this invention replaces the rubber-coated straight roller with a metal low-temperature flattening roller. Under the premise that other parameters (operator, process parameters, equipment, film type and structure, workshop temperature and humidity, etc.) remain unchanged, this change to a low-temperature flattening roller is used. Multiple sets of heat shrinkage rate tests were conducted on the produced film rolls at different temperatures (room temperature, 50℃). The test data results are as follows:

[0019] Based on this experiment, the following conclusions were drawn: After modifying the straight roller with adhesive surface to a low-temperature heated roller, the changes in heat shrinkage rate under different temperature conditions were tested. It was found that when the temperature was set at 50±1℃ and the curvature of the metal arc-shaped flattening roller was controlled at 50-60mm / m, the film heat shrinkage rate was the lowest (the heat shrinkage rates of the long and short sides decreased by -0.2 and -0.3, respectively). In subsequent production processes, a large number of repeated tests were conducted on the type of film roll and the temperature to demonstrate that the temperature of 50±1℃ and the curvature of 50-60 mm / m provided the best feedback on the heat shrinkage rate of the film roll in actual production. 4. Please refer to the above process flow diagram for the modification of the three production devices. Start the three production devices of this invention in tandem for production. Under the premise that other parameters (operators, process parameters, equipment, film type and structure, workshop temperature and humidity, etc.) remain unchanged, conduct a heat shrinkage rate test on the produced film rolls. The test data comparison results are as follows:

[0020] Through experimental verification, the following experimental conclusions were drawn: After the three production units were started in tandem, the thermal shrinkage rate of the film decreased by -1.1 mm on the long side and -1 mm on the short side, compared to data where the three units remained unchanged. In subsequent large-scale production, when changing to films with different structures, the thermal shrinkage rate decreased significantly with the three production units operating in tandem. This demonstrates that the innovative invention of the three production units effectively improves and enhances the thermal shrinkage performance of the film, with significant results.

[0021] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A production process for reducing the thermal shrinkage rate of films, characterized in that, The main steps include the following: S1. The entire process consists of three parts: pretreatment unit, roller passing unit, and quality control unit. First, in the pretreatment unit, the film roll is loaded onto the fixed roller. The fixed roller is used to fix the film roll and prevent it from swinging or moving after the machine is started. The fixed roller is made of metal and is fixed to the frame at both ends by connecting rods. S2. After passing through the fixed roller, the film roll is flattened by the metal flattening roller. The metal flattening roller is connected to the bearing seat through the bearing, and the bearing seat is installed on the frame by the anchor bolts. The surface of the metal flattening roller can rotate 360 ​​degrees independently and flexibly. S3. After the film roll is flattened by the metal flattening straight roller, it passes through three sets of roller passing devices in sequence to stretch the film roll. The specifications of these three sets of roller passing devices are the same as those of the metal flattening straight roller in the previous process. Both ends are fixed by connecting rods, which are directly welded to the frame. During normal operation, the roller surface can move flexibly in the axial tangential direction. S4. After the film roll passes through the three sets of rollers in the previous step in sequence, it enters the low-temperature heating roller. The low-temperature heating roller is designed to heat at 30°C. The heating method of the low-temperature heating roller is oil heating. The heat transfer oil is heated by an electric heating heat transfer oil furnace and then enters from one end of the low-temperature heating roller through the oil inlet pipe. Then it flows out from the other end of the low-temperature heating roller and returns to the heating furnace through the oil outlet pipe for recirculation and heating. S5. After the film roll passes through the low-temperature heating roller, it passes through a set of guide rollers in sequence. The specifications of the guide rollers are the same as those of the low-temperature heating rollers in the previous process. The two ends of the guide rollers are fixed by connecting rods, which are directly welded to the frame. During normal operation, the roller surface of the guide rollers can move flexibly in the axial tangential direction. The function of the guide rollers in this step is to stretch the film roll. S6. After the film roll passes through the roller in the previous step, it enters the roller unit in sequence and passes through the rubber-coated arc-shaped flattening roller. The rubber-coated arc-shaped flattening roller is connected to the connecting rod through the bearing. The rubber-coated arc-shaped flattening roller can rotate 360 ​​degrees independently and flexibly. S7. After passing through the adhesive surface arc flattening device in the previous step, the film roll passes through three sets of rollers in sequence. The specifications of the rollers in this step are the same as those of the adhesive surface arc flattening rollers in the previous process. Both ends of the rollers are fixed by connecting rods, which are directly welded to the frame. During normal operation, the roller surface of the rollers in this step can move flexibly in the axial tangential direction. S8. After passing through the roller unit in the previous step, the film roll enters the shaping unit. First, it passes through two sets of rollers in sequence. The specifications of the two sets of rollers in this step are the same as those of the rollers in the previous process. Both ends are fixed by connecting rods, which are directly welded to the frame. During normal operation, the roller surface in this step can move flexibly in the axial tangential direction. S9. Sequentially, the film roll that has passed through the previous process enters the high-temperature heating roller of the qualitative unit. The heating temperature of the roller surface of the high-temperature heating roller is 80℃~90℃. The heating method of the high-temperature heating roller is oil heating. The heat transfer oil is heated by an electric heating heat transfer oil furnace and then enters from one end of the high-temperature heating roller through the oil inlet pipe. Then it flows out from the other end and returns to the heating furnace through the oil outlet pipe for circulation heating and reuse. S10. Sequentially, the film roll from the previous process enters the metal low-temperature flattening roller in the shaping unit. The heating temperature of the low-temperature flattening roller in this step is 50±1℃. The design curvature of the roller surface and the contact surface between the low-temperature flattening roller and the film roll is 50-60mm / m. The heating method of the low-temperature flattening roller in this step is oil heating. The heat transfer oil is heated by an electric heating heat transfer oil furnace and then enters from one end of the low-temperature flattening roller through the oil inlet pipe. It then flows out from the other end and returns to the heating furnace through the oil outlet pipe for recirculation and heating. S11. After passing through a set of pressure rollers, the film roll from the previous process begins to be wound up. The effective diameter of the winding roller is 203.2mm. Both ends are connected and fixed to the robotic arm via connecting rods. The winding roller in this step uses a large core paper tube for winding, which makes the film less prone to wrinkling and the surface smoother. The film roll has better thermal stability in the subsequent curing process. S12. After passing through the winding rollers in sequence, the film roll is placed in a 60°C curing chamber for curing for 48 hours, after which the film roll is taken out. In step S6, the film roll comes into contact with the curved flattening roller during its travel. The change in the rotation angle of the connecting rod causes a change in the angle between the flattening roller and the film roll contact surface. The curvature of the contact surface between the curved flattening roller and the film roll is controlled at 50-70 mm / m.

2. The production process for reducing the thermal shrinkage rate of a film according to claim 1, characterized in that, In step S2, the metal flattening roller can move independently in the axial tangential direction. The movement mode is independent. Connecting rods are arranged on both sides of the metal flattening roller. After the connecting rods are properly adjusted, they are fixed. The connecting rods in this step do not move with the movement of the flattening roller surface. The bearing seats at both ends of the metal flattening roller are fixed to the equipment support by anchor bolts.

3. The production process for reducing the thermal shrinkage rate of a film according to claim 1, characterized in that, In step S6, the flattening roller in the rubber-coated arc flattening roller can move independently in the axial tangential direction. Its movement is independent. The connecting rod in the rubber-coated arc flattening roller is fixed after being properly adjusted and does not move with the movement of the flattening roller surface. The connecting rod in this step is made of metal and its curvature is fixed.

4. The production process for reducing the thermal shrinkage rate of a film according to claim 3, characterized in that, In step S6, one end of the connecting rod in the rubber-surfaced arc-shaped flattening roller is connected to the bending roller adjustment seat at the adjustment end via a bearing sleeve, and the other end of the connecting rod is connected to the bending roller adjustment seat at the fixed end via a bearing sleeve. The connecting rod is tightly engaged with the gear sleeve via a fixed key. During the adjustment process, the rotation of the lead screw can be controlled by the adjustment handle to drive the gear sleeve to rotate, thereby driving the connecting rod to rotate 360 ​​degrees in the axial tangential direction.

5. The production process for reducing the thermal shrinkage rate of a film according to claim 4, characterized in that, In step S10, connecting rods are arranged on both sides of the low-temperature flattening roller. The low-temperature flattening roller is connected to the connecting rods through bearings. The arc-shaped flattening roller surface of the low-temperature flattening roller can rotate 360 ​​degrees independently and flexibly. After the connecting rod is properly adjusted, it is fixed and does not move with the movement of the arc-shaped flattening roller surface.

6. The production process for reducing the thermal shrinkage rate of a film according to claim 5, characterized in that, In step S10, one end of the connecting rod in the low-temperature flattening roller is connected to the bending roller adjustment seat at the adjustment end through a bearing sleeve, and the other end of the connecting rod is connected to the bending roller adjustment seat at the fixed end through a bearing sleeve; the connecting rod is tightly engaged with the gear sleeve through a fixed key; during the adjustment process, the rotation of the lead screw is controlled by the adjustment handle to drive the gear sleeve to rotate, thereby driving the connecting rod to rotate 360 ​​degrees in the axial tangential direction.

Images