Mildew-proof flame-retardant polyethylene film and preparation device thereof

Abstract

The invention relates to the technical field of polyethylene film preparation, in particular to a mildew-proof flame-retardant polyethylene film and a preparation device thereof. Comprises: 100 parts of a base material; 1 part of a mildew preventive; 5 parts of a flame retardant; 5 parts of a nucleating agent and a toughening agent; 1.5 parts of a processing aid; the preparation process comprises the following steps: (1) uniformly mixing all the components according to a preset proportion, then carrying out melt blending through a twin-screw extruder to ensure that all the components are fully dispersed, and granulating by adopting an underwater granulating process; and (2) carrying out drying treatment on the granulated material particles, and preparing the mildew-proof flame-retardant polyethylene film by adopting a film blowing process. The HDPE with high strength and heat resistance and the LLDPE with good flexibility and tear resistance are mixed according to a specified proportion, the hardness and the flexibility are balanced, the mechanical property of the polyethylene film is improved, and the nano-silver and the natural antibacterial essential oil are combined, so that a stronger mildew-proof effect is achieved at a lower concentration.

Description

Technical Field

[0001] The present invention relates to the technical field of polyethylene film preparation, in particular to a mildew-proof and flame-retardant polyethylene film and a preparation device thereof. Background Art

[0002] Polyethylene, as a widely used thermoplastic, is widely used in many industries due to its excellent mechanical properties, chemical stability and processing convenience.

[0003] However, traditional polyethylene films are susceptible to mold erosion under specific environments, and their flammable properties limit their application in certain high-risk situations. With the continuous improvement of society's requirements for environmental protection and safety, the development of polyethylene films with both mold-proof and flame-retardant functions has become an urgent need for industry development. The current common method to solve the problems of polyethylene's flammability and susceptibility to mold erosion is to add flame retardants and mold inhibitors to the polyethylene blending formula system. After adding flame retardants and mold inhibitors, the presence of ordinary flame retardants and mold inhibitors will restrict the free movement of polyethylene chain segments, making the material more "rigid", resulting in a decrease in the mechanical properties of polyethylene. In order to ensure the mechanical properties of polyethylene films, a new type of mold-proof and flame-retardant polyethylene film is proposed. Summary of the Invention

[0004] In order to overcome the disadvantage that adding flame retardants and mildewproofing agents to existing polyethylene will cause a decrease in mechanical properties, the present invention provides a mildew-proof and flame-retardant polyethylene film and a preparation device thereof.

[0005] The technical solution is: a mildew-proof and flame-retardant polyethylene film, comprising:

[0006] Base material: 100 parts;

[0007] Antifungal agent: 1 part;

[0008] Flame retardant: 5 parts;

[0009] Nucleating agent and toughening agent: 5 parts;

[0010] Processing aid: 1.5 parts;

[0011] The matrix material is composed of 70 parts of HDPE particles and 30 parts of LLDPE particles; the mildew inhibitor is composed of 0.5 parts of nanosilver and 0.5 parts of natural antibacterial essential oil;

[0012] Preparation process:

[0013] All the above ingredients are mixed evenly in a predetermined ratio, then melt-blended through a twin-screw extruder to ensure that the components are fully dispersed, and granulated using an underwater granulation process;

[0014] The granulated material particles are dried and a film blowing process is used to produce a mildew-proof and flame-retardant polyethylene film.

[0015] Furthermore, the nucleating agent and toughening agent are 5 parts of organosilicon-modified montmorillonite; the processing aid is 0.5 parts of bio-based lubricant and 1 part of light stabilizer.

[0016] Furthermore, the flame retardant is 3 parts of expanded graphite and 2 parts of phosphorus-based flame retardant.

[0017] A device for preparing a mildew-proof and flame-retardant polyethylene film, comprising:

[0018] The extruder housing is mounted on the supporting box and has two screws installed inside;

[0019] A pelletizing die is installed on one side of the extruder housing. The polyethylene extruded from the extruder housing is pelletized underwater in the pelletizing die. The support box is fixedly connected to the motor and the reducer. The output shaft of the motor is fixedly connected to the input end of the reducer. The reducer is provided with two output ends.

[0020] A sliding member is slidably connected to the extruder housing, the sliding member is rotatably connected to the two screws, and the ends of the two screws away from the pelletizing die are fixedly connected to a spline rod;

[0021] The mounting plate is fixed to the supporting box, the mounting plate is rotatably connected to two toothed sleeves, the two toothed sleeves are meshed with each other, the two spline rods are spline-connected to adjacent toothed sleeves, the mounting plate is rotatably connected to a fixed sleeve, the fixed sleeve is fixed to a gear, and the gear is meshed with adjacent toothed sleeves;

[0022] Limiting member 1 is fixedly connected to the first output end of the reducer, and the first output end is located in the fixed sleeve and rotates. The fixed sleeve is spline-connected to limiting member 2. Limiting member 1 is used to limit the limiting member 2. A spring 1 is fixedly connected between the gear and the limiting member 2.

[0023] Furthermore, it also includes:

[0024] The support frame is fixedly connected to the support box, and the support frame is rotatably connected to a threaded rod. One side of the threaded rod is provided with a reciprocating thread and the other side is rotatably connected to a limiting sleeve.

[0025] The second limiting sleeve is spline-connected to the middle part of the threaded rod, and teeth are provided on the opposite sides of the second limiting sleeve and the first limiting sleeve.

[0026] Furthermore, the teeth of the limiting sleeve 1 and the limiting sleeve 2 are both provided with inclined surfaces, and the limiting sleeve 1 and the second output end of the reducer are driven by a belt and a pulley.

[0027] Furthermore, it also includes:

[0028] The first driving rod is fixedly connected to the lower side of the support frame, the second limiting sleeve is rotatably connected to the first fixing plate, and the first fixing plate on the second limiting sleeve is fixedly connected to the telescopic portion of the first driving rod;

[0029] a sliding plate, threadedly connected to the threaded portion of the threaded rod, wherein a connecting rod is fixedly connected between the sliding plate and the sliding member;

[0030] The second driving rod is fixed to the support frame by a mounting frame, the second limiting member is rotatably connected to the second fixing plate, the second driving rod is filled with hydraulic oil, and a first oil guide pipe is connected between the second driving rod and the first driving rod.

[0031] Furthermore, it also includes:

[0032] a sliding rod, slidably connected to the telescopic portion of the second driving rod, the sliding rod being fixedly connected to the second fixed plate on the second limiting member, and a tension spring being fixedly connected between the telescopic portion of the second driving rod and the second fixed plate on the second limiting member;

[0033] A limiting rod, wherein the second driving rod is fixedly connected to a mounting seat, the limiting rod is slidably connected to the mounting seat of the second driving rod, the telescopic portion of the second driving rod is provided with a blind hole, and the limiting rod is located in the blind hole of the telescopic portion of the second driving rod;

[0034] Spring 2, the limiting rod is fixed with a support plate, and the spring 2 is fixed between the support plate of the limiting rod and the mounting seat of the driving rod 2.

[0035] Furthermore, it also includes:

[0036] A fixing rod is fixedly connected to the second fixing plate of the limiting member 2, the fixing rod is provided with a limiting slot, and the mounting bracket of the driving rod 2 is fixedly connected to the driving rod 3;

[0037] The drive rod four is fixedly connected to the extruder housing, an elastic member is installed in the drive rod four, the telescopic portion of the drive rod four is in squeeze contact with the connecting rod, the drive rod four is filled with hydraulic oil, and a second oil guide pipe is connected between the drive rod four and the drive rod three.

[0038] Furthermore, an elastic member is provided in the driving rod 4, and the telescopic portion of the driving rod 3 is in sliding contact with the fixed rod.

[0039] The beneficial effects of the present invention are as follows: 1. The present invention adopts HDPE with high strength and heat resistance and LLDPE with good flexibility and tear resistance to be mixed in a specified proportion to balance hardness and flexibility, thereby improving the mechanical properties of the polyethylene film. By combining nanosilver with natural antibacterial essential oils, a stronger mildew-proof effect can be achieved at a lower concentration, reducing the use of chemical substances. In addition, a composite system of expanded graphite and phosphorus-based flame retardants is adopted. The two materials work together to form a multi-layer protection mechanism, thereby improving the flame retardant efficiency.

[0040] 2. The present invention utilizes the matching state between the first and second limit members to change the working state of the threaded rod, adjusts the relative position between the two screws and the extruder housing, and utilizes the left and right movement of the two screws to rub the large particle materials stuck between the screws and the extruder housing, so that the large particle materials are discharged from between the two, thereby preventing the large particle materials from being stuck between the two for a long time and causing mechanical damage such as scratches on the screw. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0042] Figure 2 It is a schematic diagram of the three-dimensional structure of the motor and reducer and other parts of the present invention;

[0043] Figure 3 Schematic diagram of the cross-sectional three-dimensional structure of the extruder housing of the present invention;

[0044] Figure 4 It is a schematic diagram of the three-dimensional structure of the parts such as the limiter 1 and the spring 1 of the present invention;

[0045] Figure 5 Exploded diagram of the first and second limiter parts of the present invention;

[0046] Figure 6 It is a schematic diagram of the three-dimensional structure of the support frame and threaded rods and other parts of the present invention;

[0047] Figure 7 It is a schematic diagram of the three-dimensional structure of the limiting sleeve 1 and the limiting sleeve 2 of the present invention;

[0048] Figure 8 It is a schematic diagram of the three-dimensional structure of the driving rod 2 and the fixing rod and other parts of the present invention;

[0049] Figure 9 This is a schematic diagram of the three-dimensional structure of the fixing rod and the driving rod of the present invention.

[0050] Figure numbers: 1-extruder housing, 2-granulating mold, 3-motor, 4-reducer, 5-sliding part, 6-spline rod, 7-mounting plate, 8-tooth braces, 9-fixed sleeve, 10-gear, 11-limiting part 1, 12-limiting part 2, 13-spring 1, 14-support frame, 15-threaded rod, 16-limiting sleeve 1, 17-limiting sleeve 2, 18-driving rod 1, 19-sliding plate, 20-connecting rod, 21-driving rod 2, 22-sliding rod, 23-tension spring, 24-limiting rod, 25-spring 2, 26-fixed rod, 27-driving rod 3, 28-driving rod 4. DETAILED DESCRIPTION

[0051] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0052] Example 1: A mildew-proof and flame-retardant polyethylene film, comprising: base material: 100 parts; mildew inhibitor: 1 part; flame retardant: 5 parts; nucleating agent and toughening agent: 5 parts; processing aid: 1.5 parts;

[0053] Preparation process:

[0054] 1. All the above ingredients are mixed evenly in a predetermined proportion, then melt-blended through a twin-screw extruder to ensure that the components are fully dispersed, and granulated using an underwater granulation process; 2. The granulated material particles are dried and a mildew-proof and flame-retardant polyethylene film is produced using a film blowing process.

[0055] The base material is composed of 70 parts of HDPE particles and 30 parts of LLDPE particles; the mildew inhibitor is 0.5 parts of nanosilver and 0.5 parts of natural antibacterial essential oil; the nucleating agent and toughening agent is 5 parts of silicone-modified montmorillonite; the processing aid is 0.5 parts of bio-based lubricant and 1 part of light stabilizer; the flame retardant is 3 parts of expanded graphite and 2 parts of phosphorus-based flame retardant.

[0056] When producing mildew-proof and flame-retardant polyethylene film, it is necessary to use a twin-screw extruder to melt-blend various materials, and then complete granulation. The film is produced by placing the obtained granules into a film blowing machine. However, in the process of melt-blending various materials in the twin-screw extruder, the material particles are uneven, which will cause large particles to be stuck between the screw and the barrel wall, increasing the resistance when the screw rotates, which can easily cause wear on the screw surface. At the same time, the agglomeration between various materials will also increase the resistance when the screw rotates, which can easily cause the screw to get stuck and cause serious processing accidents.

[0057] Example 2: Based on Example 1, Figure 1-Figure 5 As shown, a mildew-proof and flame-retardant polyethylene film includes: an extruder housing 1, which is installed on a supporting box and has two screws installed inside; a granulation die 2, which is installed on the left side of the extruder housing 1, and the polyethylene extruded in the extruder housing 1 is granulated underwater in the granulation die 2. The above-mentioned supporting box is fixedly connected with a motor 3 and a reducer 4, and the motor 3 and the reducer 4 are located on the right side of the extruder housing 1. The output shaft of the motor 3 is fixedly connected to the input end of the reducer 4, and the reducer 4 is provided with two output ends, which are respectively a first output end and a second output end; a sliding member 5, which is slidably connected to the extruder housing 1, and the sliding member 5 is rotationally connected to the two screws, and the right ends of the two screws are fixed with a flower Key rod 6; mounting plate 7, fixed on the support box, mounting plate 7 is rotatably connected to two tooth sleeves 8, the two tooth sleeves 8 are meshed with each other, two spline rods 6 are spline-connected to adjacent tooth sleeves 8, mounting plate 7 is rotatably connected to fixed sleeve 9, fixed sleeve 9 is fixed with gear 10, gear 10 is meshed with adjacent tooth sleeves 8; limit member 11, fixed to the first output end of reducer 4, the first output end is located in fixed sleeve 9 and rotates, fixed sleeve 9 is spline-connected to limit member 2 12, limit member 11 is used to limit limit member 2 12, a spring 13 is fixed between gear 10 and limit member 2 12, spring 13 is used to squeeze limit member 2 12 so that limit member 2 12 fits with limit member 11.

[0058] like Figure 2 、 Figure 6 and Figure 7 As shown, it also includes: a support frame 14, which is fixed to the support box body, and the support frame 14 is rotatably connected to a threaded rod 15, the left side of the threaded rod 15 is provided with a reciprocating thread, and the right side is rotatably connected to a limit sleeve 16; a limit sleeve 2 17, which is splined to the middle part of the threaded rod 15, and the opposite sides of the limit sleeve 2 17 and the limit sleeve 1 16 are provided with teeth, and the teeth of the limit sleeve 1 16 and the limit sleeve 2 17 are provided with inclined surfaces to facilitate the contact and cooperation between the two, and the limit sleeve 1 16 and the second output end of the reducer 4 are driven by a belt and a pulley.

[0059] Such as 6- Figure 9 As shown, it also includes: a driving rod 18, which is fixed to the support frame 14, a limiting sleeve 17 is rotatably connected to the first fixed plate, and the first fixed plate on the limiting sleeve 17 is fixed to the telescopic part of the driving rod 18; a sliding plate 19, which is threadedly connected to the threaded part of the threaded rod 15, and a connecting rod 20 is fixed between the sliding plate 19 and the sliding member 5; a driving rod 21, which is fixed to the lower side of the support frame 14 by using a mounting frame, and the limiting member 12 is rotatably connected to the second fixed plate, the driving rod 21 is filled with hydraulic oil, and a first oil guide pipe is connected between the driving rod 21 and the driving rod 18.

[0060] Such as 8 and Figure 9 As shown, it also includes: a sliding rod 22, which is slidably connected to the telescopic part of the driving rod 21, the sliding rod 22 is fixed to the second fixed plate on the limiting member 12, and a tension spring 23 is fixed between the telescopic part of the driving rod 21 and the second fixed plate on the limiting member 12, and the tension spring 23 is used to drive the sliding rod 22 to reset; a limiting rod 24, the driving rod 21 is fixed with a mounting seat, the limiting rod 24 is slidably connected to the mounting seat of the driving rod 21, the telescopic part of the driving rod 21 is provided with a blind hole, and the limiting rod 24 is located in the blind hole of the telescopic part of the driving rod 21; a spring 25, the limiting rod 24 is fixed with a support plate, and the spring 25 is fixed between the support plate of the limiting rod 24 and the mounting seat of the driving rod 21.

[0061] Such as 3 and Figure 9 As shown, it also includes: a fixed rod 26, which is fixedly connected to the second fixed plate of the limiting member 2 12, and the fixed rod 26 is provided with a limiting groove, and the mounting frame of the driving rod 21 is fixedly connected to the driving rod 3 27; a driving rod 4 28, which is fixedly connected to the extruder housing 1, and an elastic member is installed in the driving rod 4 28, and the elastic member is used to make the telescopic part of the driving rod 4 28 extend outward, and the telescopic part of the driving rod 4 28 is in compression contact with the connecting rod 20, and hydraulic oil is filled in the driving rod 4 28, and a second oil guide pipe is connected between the driving rod 4 28 and the driving rod 3 27, and an elastic member is provided in the driving rod 4 28, and the telescopic part of the driving rod 3 27 is in sliding contact with the fixed rod 26.

[0062] In the above scheme, the main purpose is to change the positions of the two screws when the rotational resistance of the two screws increases, so as to prevent the material from getting stuck between the inner wall of the extruder housing 1 and the two screws. A feeder is installed on the top of the extruder housing 1, which ensures the uniformity of material feeding. The pelletizing mold 2 is an existing structure, and the system structure required for underwater pelletizing is not specifically shown in the accompanying drawings. A driving motor is provided on the left side of the pelletizing mold 2, a heating element is installed on the outside of the extruder housing 1, and the outer shape of the sliding member 5 is in contact with the inner wall of the cavity of the extruder housing 1. In order to prevent the material from getting stuck between the sliding member 5 and the extruder housing 1, a high-temperature resistant seal can be installed on the outside of the sliding member 5, and the teeth of the limiter 11 and the limiter 2 12 are both set to an inclined shape (such as Figure 5 ), and in the initial state, under the elastic force of the spring 13, the teeth of the limiter 11 and the limiter 2 12 are in a meshing state, and the two screws are in the process of normal rotation of the extruder housing 1, and the limiter 11 and the limiter 2 12 are in a tightly fitted state (such as Figure 4 ), the elastic force of spring 13 is sufficient to maintain the matching state of limit member 11 and limit member 2 12 during normal operation, the limit sleeve 16 and the second output end of the reducer 4 are both equipped with pulleys and the two are driven by a belt, and the driving rod 18 is located on the rear side of the threaded rod 15.

[0063] Working process: When using this device, first preheat the device, then the staff starts the motor 3, the feeder starts feeding, the output shaft of the motor 3 drives the input end of the reducer 4 to rotate, the first output end and the second output end of the reducer 4 rotate synchronously, the first output end of the reducer 4 drives the limiter 11 to rotate, the limiter 11 drives the limiter 2 12 to rotate synchronously through the teeth, the spring 13 is in the storage state, the limiter 2 12 drives the fixed sleeve 9 and the gear 10 to rotate synchronously through the spline, the gear 10 drives the front tooth sleeve 8 to rotate through the teeth, and at this time the two gears The toothed sleeve 8 rotates on the mounting plate 7 in opposite directions, and the toothed sleeve 8 drives the spline rod 6 thereon to rotate. The two spline rods 6 drive the two screws to rotate on the sliding member 5 and in the extruder housing 1. The two screws push the material to the left. The material is melt-blended in the extruder housing 1 and extruded from the pelletizing die 2 to complete pelletizing. During the rotation of the two output ends of the reducer 4, the second output end of the reducer 4 drives the limit sleeve 16 to rotate synchronously through the pulley and belt. The limit sleeve 16 rotates on the threaded rod 15. At this time, the limit sleeve 16 and the limit sleeve 2 17 are not in contact.

[0064] When the second stopper 12 is engaged, the second stopper 12 is engaged, and the second stopper 12 is engaged, so that the second stopper 12 is engaged, and the second stopper 12 is engaged, so that the second stopper 12 is engaged, and the second stopper 12 is engaged, so that the second stopper 12 is engaged, and the second stopper 12 is engaged, so that the second stopper 12 is engaged, and the second stopper 12 is engaged, so that the second stopper 12 is engaged, so that the second stopper 12 is engaged, and the second stopper 12 is engaged, so that the second stopper 12 is engaged, so that the second stopper 12 is engaged, and the second stopper 12 is engaged When the limit force is greater than the blind hole limit force of the limit rod 24 and the driving rod 21, the limit rod 24 moves upward, and the spring 25 is compressed at the same time, and the telescopic portion of the driving rod 21 is released from the limit. Subsequently, under the tension of the tension spring 23, the telescopic portion of the driving rod 21 extends, and the hydraulic oil in the driving rod 21 flows into the driving rod 1 along the first oil guide pipe. The telescopic portion of the driving rod 18 extends outward, and the telescopic portion of the driving rod 18 drives the limit sleeve 2 17 to move right, and the limit sleeve 2 1 7 slides to the right along the threaded rod 15 until the limiting sleeve 2 17 and the limiting sleeve 1 16 contact and cooperate with each other, the limiting sleeve 1 16 drives the limiting sleeve 2 17 to rotate synchronously, the limiting sleeve 2 17 drives the threaded rod 15 to rotate through the spline, the threaded portion of the threaded rod 15 drives the sliding plate 19 to move to the right through the thread, the sliding plate 19 drives the sliding member 5 to slide to the right through the connecting rod 20, and the sliding member 5 drives the two screws to move to the right synchronously, thereby changing the relative position between the screw and the extruder housing 1.

[0065] When the sliding plate 19 moves to the right, the sliding plate 19 drives the sliding member 5 and the two screw rods to move to the left. In the process of the sliding plate 19 moving to the left, if the resistance encountered by the two screw rods when rotating is restored, the telescopic end of the driving rod 3 27 limits the fixed rod 26, and the limiting member 12 The hydraulic oil in the driving rod 18 flows back into the driving rod 21, and the telescopic part of the driving rod 18 drives the limiting sleeve 21 to move to the left and reset. The limiting sleeve 21 separates from the limiting sleeve 16, and the threaded rod 15 stops rotating, and the sliding plate 19 is reset to the initial state at the same time.

[0066] When the sliding plate 19 moves to the left, the rotational resistance of the two screws does not decrease. After the sliding plate 19 moves to the left, it continues to move to the right. When the staff uses the device, they can know the status of the two screws in the extruder housing 1 according to the moving status of the sliding plate 19, so as to perform maintenance or cleaning at the most reasonable time. When the device is stopped, the staff will turn off the reducer 4 and the drive motor on the left side of the extruder housing 1 to stop granulation.

[0067] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A mildew-proof and flame-retardant polyethylene film, characterized in that: Includes: Base material: 100 parts; Antifungal agent: 1 part; Flame retardant: 5 parts; Nucleating agent and toughening agent: 5 parts; Processing aid: 1.5 parts; The matrix material is composed of 70 parts of HDPE particles and 30 parts of LLDPE particles; the mildew inhibitor is composed of 0.5 parts of nanosilver and 0.5 parts of natural antibacterial essential oil; Preparation process: All the above ingredients are mixed evenly in a predetermined ratio, then melt-blended through a twin-screw extruder to ensure that the components are fully dispersed, and granulated using an underwater granulation process; The granulated material particles are dried and a film blowing process is used to produce a mildew-proof and flame-retardant polyethylene film.

2. The mildew-proof and flame-retardant polyethylene film according to claim 1, characterized in that: The nucleating agent and toughening agent are 5 parts of silicone-modified montmorillonite; the processing aids are 0.5 parts of bio-based lubricant and 1 part of light stabilizer.

3. The mildew-proof and flame-retardant polyethylene film according to claim 2, characterized in that: The flame retardant is 3 parts of expanded graphite and 2 parts of phosphorus flame retardant.

4. A device for preparing mildew-proof and flame-retardant polyethylene film, characterized in that: Includes: An extruder housing (1) is mounted on the supporting box and has two screws installed inside; A pelletizing die (2) is installed on one side of the extruder housing (1), and the polyethylene extruded from the extruder housing (1) is pelletized underwater in the pelletizing die (2). The support box is fixedly connected to a motor (3) and a reducer (4), and the output shaft of the motor (3) is fixedly connected to the input end of the reducer (4). The reducer (4) is provided with two output ends. A sliding member (5) is slidably connected to the extruder housing (1), the sliding member (5) is rotatably connected to the two screws, and the ends of the two screws away from the pelletizing die (2) are fixedly connected to a spline rod (6); The mounting plate (7) is fixed on the supporting box body. The mounting plate (7) is rotatably connected to two tooth sleeves (8). The two tooth sleeves (8) are meshed with each other. The two spline rods (6) are spline-connected to the adjacent tooth sleeves (8). The mounting plate (7) is rotatably connected to a fixed sleeve (9). The fixed sleeve (9) is fixed with a gear (10). The gear (10) is meshed with the adjacent tooth sleeves (8). A limiting member 1 (11) is fixedly connected to the first output end of the reducer (4), and the first output end is located in the fixed sleeve (9) and rotates. The fixed sleeve (9) is spline-connected to the limiting member 2 (12). The limiting member 1 (11) is used to limit the limiting member 2 (12). A spring 1 (13) is fixedly connected between the gear (10) and the limiting member 2 (12).

5. The mildew-proof and flame-retardant polyethylene film according to claim 4, characterized in that: Also included are: The support frame (14) is fixed to the support box, and the support frame (14) is rotatably connected to a threaded rod (15). One side of the threaded rod (15) is provided with a reciprocating thread and the other side is rotatably connected to a limiting sleeve (16); a limiting sleeve (17) is spline-connected to the middle part of the threaded rod (15), and teeth are provided on the opposite sides of the limiting sleeve (17) and the limiting sleeve (16).

6. The mildew-proof and flame-retardant polyethylene film according to claim 5, characterized in that: The teeth of the limiting sleeve 1 (16) and the limiting sleeve 2 (17) are both provided with inclined surfaces, and the limiting sleeve 1 (16) and the second output end of the reducer (4) are driven by a belt and a pulley.

7. The mildew-proof and flame-retardant polyethylene film according to claim 6, characterized in that: Also included are: The driving rod (18) is fixedly connected to the support frame (14), the limiting sleeve (17) is rotatably connected to the first fixing plate, and the first fixing plate on the limiting sleeve (17) is fixedly connected to the telescopic part of the driving rod (18); a sliding plate (19) threadedly connected to the threaded portion of the threaded rod (15), and a connecting rod (20) fixedly connected between the sliding plate (19) and the sliding member (5); The second driving rod (21) is fixed to the lower side of the support frame (14) by using a mounting frame, the second limiting member (12) is rotatably connected to a second fixed plate, the second driving rod (21) is filled with hydraulic oil, and a first oil guide pipe is connected between the second driving rod (21) and the first driving rod (18).

8. The mildew-proof and flame-retardant polyethylene film according to claim 7, characterized in that: Also included are: A sliding rod (22) is slidably connected to the telescopic portion of the second driving rod (21), the sliding rod (22) is fixedly connected to the second fixed plate on the second limiting member (12), and a tension spring (23) is fixedly connected between the telescopic portion of the second driving rod (21) and the second fixed plate on the second limiting member (12); A limiting rod (24), the second driving rod (21) is fixedly connected with a mounting seat, the limiting rod (24) is slidably connected to the mounting seat of the second driving rod (21), the telescopic portion of the second driving rod (21) is provided with a blind hole, and the limiting rod (24) is located in the blind hole of the telescopic portion of the second driving rod (21); Spring 2 (25), the limiting rod (24) is fixed with a support plate, and the spring 2 (25) is fixed between the support plate of the limiting rod (24) and the mounting seat of the driving rod 2 (21).

9. The mildew-proof and flame-retardant polyethylene film according to claim 8, characterized in that: Also included are: A fixing rod (26) is fixedly connected to the second fixing plate of the second limiting member (12), the fixing rod (26) is provided with a limiting groove, and the mounting frame of the second driving rod (21) is fixedly connected to the third driving rod (27); The driving rod four (28) is fixedly connected to the extruder housing (1), an elastic member is installed in the driving rod four (28), the telescopic portion of the driving rod four (28) is in squeeze contact with the connecting rod (20), the driving rod four (28) is filled with hydraulic oil, and a second oil guide pipe is connected between the driving rod four (28) and the driving rod three (27).

10. The mildew-proof and flame-retardant polyethylene film according to claim 9, characterized in that: An elastic member is provided in the driving rod four (28), and the telescopic portion of the driving rod three (27) is in sliding contact with the fixed rod (26).

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