A three-bubble five-layer co-extrusion production process for an easy-to-tear cross-linked heat shrinkable film

Abstract

The present invention is applicable to the technical field of heat shrinkable films, and provides a three-bubble method five-layer co-extrusion production process for an easy-to-tear cross-linked heat shrinkable film, comprising the following steps: preparing raw materials for five film layers; after uniformly mixing the raw materials for each film layer, respectively adding them to a five-layer circular extruder for extrusion, and stacking multiple layers to form a first film bubble; subjecting the first film bubble to secondary water cooling molding to obtain a first film body; subjecting the first film body to a three-stage heating treatment, and then inflating it to form a second film bubble, and then cooling it through cold air circulation to obtain a second film body; subjecting the second film body to dotted line punching equipment to dotted line punching, and then cross-linking it using an electron beam as an irradiation source; the present invention adopts a three-bubble method to prepare a five-layer composite film layer structure to achieve a straight line tearing effect; by adding modified nano-expanded perlite to the film layer raw materials and sodium lignin sulfonate at the same time, the two have a synergistic effect, and the mechanical properties of the heat shrinkable film are further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of heat shrinkable films, and in particular relates to a three-bubble five-layer co-extrusion production process of an easy-to-tear cross-linked heat shrinkable film. Background Art

[0002] Heat shrink film is used for the sale and transportation of various products. Its main function is to stabilize, cover and protect the products. The shrink film must have high puncture resistance, good shrinkage and certain shrinkage stress. During the shrinking process, the film cannot have holes.

[0003] How to open the package conveniently and quickly has become a trend. The easy-tear design of food and drug outer packaging reflects the convenience of life. Existing easy-tear heat shrink films are generally easy to tear by making a tear; due to the poor tearing guidance of the tearing edge, it often leads to poor tearing or uneven tearing edges, causing the contents to spill. Summary of the invention

[0004] The present invention provides a three-bubble five-layer co-extrusion production process for an easy-to-tear cross-linked heat shrinkable film, aiming to solve the above-mentioned problem.

[0005] The present invention is achieved by a three-bubble five-layer co-extrusion production process of an easy-to-tear cross-linked heat shrinkable film, comprising the following steps:

[0006] Prepare raw materials for five membrane layers;

[0007] After the raw materials of each film layer are mixed evenly, they are added to the five-layer circular extruder for extrusion, and multiple layers are superimposed to form the first film bubble;

[0008] The first film bubble is subjected to secondary water cooling to obtain a first film body;

[0009] The first film body is subjected to a three-stage heating treatment, and then inflated by air to form a second film bubble, and then cooled by cold air circulation to obtain a second film body, wherein the inflation ratio in the second bubble inflation is preferably 4.5-5.5, and the stretching ratio is 3-6;

[0010] The second film body is perforated with dotted lines by using a dotted line perforating device, and then cross-linked by using an electron beam as a radiation source to obtain the desired tearable cross-linked heat shrinkable film.

[0011] Preferably, in the secondary water-cooling forming, the temperature of the first water-cooling is 15-20°C, and the temperature of the second water-cooling is 20-25°C.

[0012] Preferably, the temperatures of the three-stage heating treatment are controlled to be 180-190°C, 150-170°C and 90-110°C respectively.

[0013] Preferably, in the cross-linking treatment, the energy of the electron beam is 0.5-1.5 MeV, the absorbed dose is 120-140 kGy, and the irradiation speed is 100-120 m / min.

[0014] Preferably, in parts by weight, the raw materials of each film layer include: 50-60 parts of linear low-density polyethylene, 25-35 parts of cyclic polyolefin, 10-15 parts of ethylene-vinyl acetate copolymer, 4-8 parts of modified nano-expanded perlite, 2-4 parts of sodium lignin sulfonate, 2-5 parts of polyurethane acrylate, and 1-3 parts of epoxy soybean oil.

[0015] Preferably, in parts by weight, the raw materials of each film layer include: 52-58 parts of linear low-density polyethylene, 28-32 parts of cyclic polyolefin, 11-14 parts of ethylene-vinyl acetate copolymer, 5-7 parts of modified nano-expanded perlite, 2.5-3.5 parts of sodium lignin sulfonate, 3-4 parts of polyurethane acrylate, and 1.5-2.5 parts of epoxy soybean oil.

[0016] Preferably, in parts by weight, the raw materials of each film layer include: 55 parts of linear low-density polyethylene, 30 parts of cyclic polyolefin, 12.5 parts of ethylene-vinyl acetate copolymer, 6 parts of modified nano-expanded perlite, 3 parts of sodium lignin sulfonate, 3.5 parts of polyurethane acrylate, and 2 parts of epoxy soybean oil.

[0017] Preferably, the preparation method of the modified nano expanded perlite is as follows: take expanded perlite, clean the surface, dry and then perform preliminary crushing; then place it in a muffle furnace and program the temperature to 600-700°C, constant temperature roasting for 1-2h, and grind it to a particle size of 100-200 mesh after cooling; then add 25-35vt% hydrochloric acid solution and soak for 2-4h; filter to obtain a solid product, put the solid product into a culture vessel and inject bacterial cellulose fermentation liquid, wrap it, and culture it at 25-30°C for 3-5 days, rinse the culture product with deionized water, remove the residual culture liquid, soak it with deionized water for 3-5h, and finally filter, dry and grind to obtain the modified nano expanded perlite. The expanded perlite is first calcined to remove water in different states in the structure, making the internal structure loose and porous and increasing the specific surface area. The expanded perlite is then surface-corroded and modified by hydrochloric acid to form a stable porous structure on the surface of the expanded perlite. During the fermentation process, bacterial cellulose grows into the expanded perlite to form an interlaced interpenetrating network, thereby improving the mechanical properties of the nano-expanded perlite.

[0018] Preferably, the preparation method of the bacterial cellulose fermentation liquid is as follows: inoculating Gluconacetobacter species into the culture liquid, the temperature is 25-28°C, the stirring speed is 200-240r / min, and the culture time is 24-36h to obtain seed liquid; the seed liquid with a volume of 6-10% of the culture liquid is added to the culture liquid, mixed and set aside, to obtain bacterial cellulose fermentation liquid.

[0019] Preferably, the dotted line punching device comprises:

[0020] A mounting frame, the mounting frame comprising a base plate and a door-shaped frame fixed on the base plate;

[0021] Two sets of scissor-type mechanisms are installed in the portal frame symmetrically in front and back, and a plurality of support rollers are installed between the two sets of scissor-type mechanisms, and adjacent support rollers are respectively located at both ends of a scissor-type rod;

[0022] A mounting rod is vertically arranged on the side of the two groups of scissor-fork mechanisms away from the support rollers, a guide sleeve is sleeved on the mounting rod, the guide sleeve is hinged to the end of the scissor-fork mechanism where the support rollers are installed, one end of the mounting rod away from the support rollers is hinged to the end of the scissor-fork mechanism away from the support rollers, a mounting plate is fixed to the end of the mounting rod close to the support rollers, a perforated needle plate is arranged on the side of the mounting plate close to the support rollers, and both ends of the perforated needle plate are fixedly connected to the mounting plate through support rods;

[0023] A power mechanism for driving the extension and retraction of the scissor mechanism, the power mechanism comprising a stepping motor, a bidirectional screw and an internal threaded sleeve. Bidirectional screws are rotatably installed on both sides of the portal frame and can be rotatably installed through bearings. A stepping motor is fixed on the top of the portal frame to drive a bidirectional screw to rotate. The two bidirectional screws are connected by a transmission structure. Internal threaded sleeves are respectively threaded on the two threaded sections of the bidirectional screw. One of the internal threaded sleeves is connected to an adjacent guide sleeve, and the other internal threaded sleeve is connected to an adjacent mounting rod end.

[0024] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0025] The three-bubble method five-layer co-extrusion production process of the easy-tear cross-linked heat shrinkable film provided by the present invention adopts the three-bubble method to prepare a five-layer composite film structure, the film layer uses linear low-density polyethylene and cyclic polyolefin as main raw materials, and the anisotropy of the film is achieved by adjusting the stretching ratio and the blowing ratio, the blowing ratio is 4.5-5.5, and the stretching ratio is 3-6, so that a continuous sea-island structure is formed inside the film to achieve a straight-line tearing effect; by adding modified nano-expanded perlite to the film layer raw material, the mechanical properties are improved, and at the same time, sodium lignin sulfonate is added, the two have a synergistic effect, and the mechanical properties of the heat shrinkable film are further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of a three-bubble method five-layer co-extrusion production process of an easy-tear cross-linked heat shrinkable film provided by the present invention;

[0027] Figure 2 It is a structural schematic diagram of a three-bubble method five-layer co-extrusion production process of an easy-tear cross-linked heat shrinkable film provided by the present invention;

[0028] Figure 3 It is a structural schematic diagram of a three-bubble method five-layer co-extrusion production process of an easy-tear cross-linked heat shrinkable film provided by the present invention;

[0029] Figure 4 The present invention provides a schematic diagram of the overall structure of a three-bubble five-layer co-extrusion production process for an easy-to-tear cross-linked heat shrinkable film.

[0030] Notes on the accompanying drawings: 1. Base plate; 2. Door frame; 3. Scissor mechanism; 4. Mounting rod; 5. Guide sleeve; 6. Mounting plate; 7. Support rod; 8. Support roller; 9. Bidirectional screw rod; 10. Stepper motor; 11. Transmission structure; 12. Internal threaded sleeve; 13. Punch needle plate. DETAILED DESCRIPTION

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of this application; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0032] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0033] Example 1

[0034] The embodiment of the present invention provides a three-bubble five-layer co-extrusion production process for an easy-to-tear cross-linked heat shrinkable film, such as Figure 1 As shown, the following steps are included:

[0035] Prepare raw materials for five membrane layers;

[0036] After the raw materials of each film layer are mixed evenly, they are added to the five-layer circular extruder for extrusion, and multiple layers are superimposed to form the first film bubble;

[0037] The first film bubble is subjected to secondary water cooling to obtain a first film body;

[0038] The first film body is subjected to a three-stage heating treatment, and then inflated by air to form a second film bubble, and then cooled by cold air circulation to obtain a second film body. In this embodiment, the inflation ratio in the second bubble inflation is 4.5, and the stretching ratio is 3;

[0039] The second film body is perforated with dotted lines by using a dotted line perforating device, and then cross-linked by using an electron beam as a radiation source to obtain the desired tearable cross-linked heat shrinkable film.

[0040] Among them, the temperature of the first water cooling in the secondary water cooling forming is 15°C, and the temperature of the second water cooling is 20°C.

[0041] Specifically, the temperatures of the three-stage heating treatment are controlled to be 180° C., 150° C. and 90° C. respectively.

[0042] In a specific implementation, the energy of the electron beam in the cross-linking treatment is 0.5 MeV, the absorbed dose is 120 kGy, and the irradiation speed is 100 m / min.

[0043] In this embodiment, the raw materials of each film layer include, by weight: 50 parts of linear low-density polyethylene, 25 parts of cyclic polyolefin, 10 parts of ethylene vinyl acetate copolymer, 4 parts of modified nano-expanded perlite, 2 parts of sodium lignin sulfonate, 2 parts of polyurethane acrylate, and 1 part of epoxy soybean oil.

[0044] Preferably, the preparation method of the modified nano expanded perlite is as follows: take expanded perlite, clean the surface, dry it and then perform preliminary crushing; then place it in a muffle furnace and program the temperature to 600°C, calcine it at a constant temperature for 1 hour, and grind it to a particle size of 100 mesh after cooling; then add 25vt% hydrochloric acid solution and soak it for 2 hours; filter to obtain a solid product, put the solid product into a culture vessel and inject bacterial cellulose fermentation liquid, wrap it, and culture it at 25°C for 3 days, rinse the culture product with deionized water, remove the residual culture liquid, soak it with deionized water for 3 hours, and finally filter, dry and grind it to obtain the modified nano expanded perlite.

[0045] The preparation method of the bacterial cellulose fermentation liquid is as follows: inoculating Gluconacetobacter species into the culture liquid, the temperature is 25°C, the stirring speed is 200r / min, and the culture time is 24h to obtain seed liquid; the seed liquid with a volume of 6% of the culture liquid is added to the culture liquid, mixed and set aside to obtain bacterial cellulose fermentation liquid.

[0046] Example 2

[0047] The embodiment of the present invention provides a three-bubble five-layer co-extrusion production process for an easy-to-tear cross-linked heat shrinkable film, such as Figure 1 As shown, the following steps are included:

[0048] Prepare raw materials for five membrane layers;

[0049] After the raw materials of each film layer are mixed evenly, they are added to the five-layer circular extruder for extrusion, and multiple layers are superimposed to form the first film bubble;

[0050] The first film bubble is subjected to secondary water cooling to obtain a first film body;

[0051] The first film body is subjected to a three-stage heating treatment, and then inflated by air to form a second film bubble, and then cooled by cold air circulation to obtain a second film body. In this embodiment, the inflation ratio in the second bubble inflation is 4.5, and the stretching ratio is 3;

[0052] The second film body is perforated with dotted lines by using a dotted line perforating device, and then cross-linked by using an electron beam as a radiation source to obtain the desired tearable cross-linked heat shrinkable film.

[0053] Among them, the temperature of the first water cooling in the secondary water cooling forming is 15°C, and the temperature of the second water cooling is 20°C.

[0054] Specifically, the temperatures of the three-stage heating treatment are controlled to be 180° C., 150° C. and 90° C. respectively.

[0055] In a specific implementation, the energy of the electron beam in the cross-linking treatment is 0.5 MeV, the absorbed dose is 120 kGy, and the irradiation speed is 100 m / min.

[0056] In this embodiment, the raw materials of each film layer include, by weight: 52 parts of linear low-density polyethylene, 28 parts of cyclic polyolefin, 11 parts of ethylene vinyl acetate copolymer, 5 parts of modified nano-expanded perlite, 2.5 parts of sodium lignin sulfonate, 3 parts of polyurethane acrylate, and 1.5 parts of epoxy soybean oil.

[0057] Preferably, the preparation method of the modified nano expanded perlite is as follows: take expanded perlite, clean the surface, dry it and then perform preliminary crushing; then place it in a muffle furnace and program the temperature to 600°C, calcine it at a constant temperature for 1 hour, and grind it to a particle size of 100 mesh after cooling; then add 25vt% hydrochloric acid solution and soak it for 2 hours; filter to obtain a solid product, put the solid product into a culture vessel and inject bacterial cellulose fermentation liquid, wrap it, and culture it at 25°C for 3 days, rinse the culture product with deionized water, remove the residual culture liquid, soak it with deionized water for 3 hours, and finally filter, dry and grind it to obtain the modified nano expanded perlite.

[0058] The preparation method of the bacterial cellulose fermentation liquid is as follows: inoculating Gluconacetobacter species into the culture liquid, the temperature is 25°C, the stirring speed is 200r / min, and the culture time is 24h to obtain seed liquid; the seed liquid with a volume of 6% of the culture liquid is added to the culture liquid, mixed and set aside to obtain bacterial cellulose fermentation liquid.

[0059] Example 3

[0060] The embodiment of the present invention provides a three-bubble five-layer co-extrusion production process for an easy-to-tear cross-linked heat shrinkable film, such as Figure 1 As shown, the following steps are included:

[0061] Prepare raw materials for five membrane layers;

[0062] After the raw materials of each film layer are mixed evenly, they are added to the five-layer circular extruder for extrusion, and multiple layers are superimposed to form the first film bubble;

[0063] The first film bubble is subjected to secondary water cooling to obtain a first film body;

[0064] The first film body is subjected to a three-stage heating treatment, and then inflated by air to form a second film bubble, and then cooled by cold air circulation to obtain a second film body. In this embodiment, the inflation ratio in the second bubble inflation is 5, and the stretching ratio is 4.5;

[0065] The second film body is perforated with dotted lines by using a dotted line perforating device, and then cross-linked by using an electron beam as a radiation source to obtain the desired tearable cross-linked heat shrinkable film.

[0066] Among them, the temperature of the first water cooling in the secondary water cooling forming is 18°C, and the temperature of the second water cooling is 22°C.

[0067] Specifically, the temperatures of the three-stage heating treatment are controlled to be 185° C., 160° C. and 100° C. respectively.

[0068] In a specific implementation, the energy of the electron beam in the cross-linking treatment is 1 MeV, the absorbed dose is 130 kGy, and the irradiation speed is 110 m / min.

[0069] In this embodiment, the raw materials of each film layer include, by weight: 55 parts of linear low-density polyethylene, 30 parts of cyclic polyolefin, 12.5 parts of ethylene-vinyl acetate copolymer, 6 parts of modified nano-expanded perlite, 3 parts of sodium lignin sulfonate, 3.5 parts of polyurethane acrylate, and 2 parts of epoxy soybean oil.

[0070] Preferably, the preparation method of the modified nano expanded perlite is as follows: take the expanded perlite, clean the surface, dry it and then perform preliminary crushing; then place it in a muffle furnace and program the temperature to 650°C, calcine it at a constant temperature for 1.5 hours, and grind it to a particle size of 100 mesh after cooling; then add 30vt% hydrochloric acid solution and soak it for 3 hours; filter to obtain a solid product, put the solid product into a culture vessel and inject bacterial cellulose fermentation liquid, wrap it, and culture it at 28°C for 4 days, rinse the culture product with deionized water, remove the residual culture liquid, soak it with deionized water for 4 hours, and finally filter, dry and grind it to obtain the modified nano expanded perlite.

[0071] The preparation method of the bacterial cellulose fermentation liquid is as follows: inoculating Gluconacetobacter species into the culture liquid, the temperature is 26.5°C, the stirring speed is 220r / min, and the culture time is 30h to obtain seed liquid; the seed liquid with a volume of 8% of the culture liquid is added to the culture liquid, mixed and set aside to obtain bacterial cellulose fermentation liquid.

[0072] Example 4

[0073] The embodiment of the present invention provides a three-bubble five-layer co-extrusion production process for an easy-to-tear cross-linked heat shrinkable film, such as Figure 1 As shown, the following steps are included:

[0074] Prepare raw materials for five membrane layers;

[0075] After the raw materials of each film layer are mixed evenly, they are added to the five-layer circular extruder for extrusion, and multiple layers are superimposed to form the first film bubble;

[0076] The first film bubble is subjected to secondary water cooling to obtain a first film body;

[0077] The first film body is subjected to a three-stage heating treatment, and then inflated by air to form a second film bubble, and then cooled by cold air circulation to obtain a second film body. In this embodiment, the inflation ratio in the second bubble inflation is 5.5 and the stretching ratio is 6;

[0078] The second film body is perforated with dotted lines by using a dotted line perforating device, and then cross-linked by using an electron beam as a radiation source to obtain the desired tearable cross-linked heat shrinkable film.

[0079] Among them, the temperature of the first water cooling in the secondary water cooling forming is 20°C, and the temperature of the second water cooling is 25°C.

[0080] Specifically, the temperatures of the three-stage heating treatment are controlled to be 190° C., 170° C. and 110° C. respectively.

[0081] In a specific implementation, the energy of the electron beam in the cross-linking treatment is 1.5 MeV, the absorbed dose is 140 kGy, and the irradiation speed is 120 m / min.

[0082] In this embodiment, the raw materials of each film layer include, by weight: 58 parts of linear low-density polyethylene, 32 parts of cyclic polyolefin, 14 parts of ethylene vinyl acetate copolymer, 7 parts of modified nano-expanded perlite, 3.5 parts of sodium lignin sulfonate, 4 parts of polyurethane acrylate, and 2.5 parts of epoxy soybean oil.

[0083] Preferably, the preparation method of the modified nano expanded perlite is as follows: take expanded perlite, clean the surface, dry it and then perform preliminary crushing; then place it in a muffle furnace and program the temperature to 700°C, calcine it at a constant temperature for 2 hours, and grind it to a particle size of 100 mesh after cooling; then add 35vt% hydrochloric acid solution and soak it for 4 hours; filter to obtain a solid product, put the solid product into a culture vessel and inject bacterial cellulose fermentation liquid, wrap it, and culture it at 30°C for 5 days, rinse the culture product with deionized water, remove the residual culture liquid, soak it with deionized water for 5 hours, and finally filter, dry and grind to obtain the modified nano expanded perlite.

[0084] The preparation method of the bacterial cellulose fermentation liquid is as follows: inoculating Gluconacetobacter species into the culture liquid, the temperature is 28°C, the stirring speed is 240r / min, and the culture time is 36h to obtain seed liquid; the seed liquid with a volume of 10% of the culture liquid is added to the culture liquid, mixed and set aside to obtain bacterial cellulose fermentation liquid.

[0085] Example 5

[0086] The embodiment of the present invention provides a three-bubble five-layer co-extrusion production process for an easy-to-tear cross-linked heat shrinkable film, such as Figure 1 As shown, the following steps are included:

[0087] Prepare raw materials for five membrane layers;

[0088] After the raw materials of each film layer are mixed evenly, they are added to the five-layer circular extruder for extrusion, and multiple layers are superimposed to form the first film bubble;

[0089] The first film bubble is subjected to secondary water cooling to obtain a first film body;

[0090] The first film body is subjected to a three-stage heating treatment, and then inflated by air to form a second film bubble, and then cooled by cold air circulation to obtain a second film body. In this embodiment, the inflation ratio in the second bubble inflation is 5.5 and the stretching ratio is 6;

[0091] The second film body is perforated with dotted lines by using a dotted line perforating device, and then cross-linked by using an electron beam as a radiation source to obtain the desired tearable cross-linked heat shrinkable film.

[0092] Among them, the temperature of the first water cooling in the secondary water cooling forming is 20°C, and the temperature of the second water cooling is 25°C.

[0093] Specifically, the temperatures of the three-stage heating treatment are controlled to be 190° C., 170° C. and 110° C. respectively.

[0094] In a specific implementation, the energy of the electron beam in the cross-linking treatment is 1.5 MeV, the absorbed dose is 140 kGy, and the irradiation speed is 120 m / min.

[0095] In this embodiment, the raw materials of each film layer include, by weight: 60 parts of linear low-density polyethylene, 35 parts of cyclic polyolefin, 15 parts of ethylene vinyl acetate copolymer, 8 parts of modified nano-expanded perlite, 4 parts of sodium lignin sulfonate, 5 parts of polyurethane acrylate, and 3 parts of epoxy soybean oil.

[0096] Preferably, the preparation method of the modified nano expanded perlite is as follows: take expanded perlite, clean the surface, dry it and then perform preliminary crushing; then place it in a muffle furnace and program the temperature to 700°C, calcine it at a constant temperature for 2 hours, and grind it to a particle size of 100 mesh after cooling; then add 35vt% hydrochloric acid solution and soak it for 4 hours; filter to obtain a solid product, put the solid product into a culture vessel and inject bacterial cellulose fermentation liquid, wrap it, and culture it at 30°C for 5 days, rinse the culture product with deionized water, remove the residual culture liquid, soak it with deionized water for 5 hours, and finally filter, dry and grind to obtain the modified nano expanded perlite.

[0097] The preparation method of the bacterial cellulose fermentation liquid is as follows: inoculating Gluconacetobacter species into the culture liquid, the temperature is 28°C, the stirring speed is 240r / min, and the culture time is 36h to obtain seed liquid; the seed liquid with a volume of 10% of the culture liquid is added to the culture liquid, mixed and set aside to obtain bacterial cellulose fermentation liquid.

[0098] Example 6

[0099] like Figure 2-Figure 4 As shown, the dotted line punching device used in embodiments 1-5 includes:

[0100] A mounting frame, the mounting frame comprising a base plate 1 and a door-shaped frame 2 fixed on the base plate 1;

[0101] Two sets of scissor-type fork mechanisms 3 are installed in the door frame 2 in a front-to-back symmetric manner, and a plurality of support rollers 8 are installed between the two sets of the scissor-type fork mechanisms 3, and adjacent support rollers 8 are respectively located at both ends of a scissor-type fork rod;

[0102] A mounting rod 4 is vertically arranged on the side of the two groups of scissor-fork mechanisms 3 away from the support roller 8, and a guide sleeve 5 is sleeved on the mounting rod 4. The guide sleeve 5 is hinged to the end of the scissor-fork mechanism 3 on which the support roller 8 is installed. One end of the mounting rod 4 away from the support roller 8 is hinged to the end of the scissor-fork mechanism 3 away from the support roller 8. A mounting plate 6 is fixed to the end of the mounting rod 4 close to the support roller 8. A perforated needle plate 13 is provided on the side of the mounting plate 6 close to the support roller 8. Both ends of the perforated needle plate 13 are fixedly connected to the mounting plate 6 through support rods 7;

[0103] A power mechanism for driving the scissor mechanism 3 to extend and retract, the power mechanism comprising a stepper motor 10, a bidirectional screw rod 9 and an internal threaded sleeve 12. The bidirectional screw rods 9 are rotatably installed on both sides of the portal frame 2, and can be rotatably installed through bearings. A stepper motor 10 is fixed on the top of the portal frame 2, which can be fixed by bolts and is used to drive a bidirectional screw rod 9 to rotate. The two bidirectional screw rods 9 are connected by a transmission structure 11, which can be a belt or synchronous belt transmission structure 11. The two threaded sections of the bidirectional screw rod 9 are respectively threaded with internal threaded sleeves 12. One of the internal threaded sleeves 12 is connected to the adjacent guide sleeve 5, and the other internal threaded sleeve 12 is connected to the adjacent end of the mounting rod 4. It can be a rotatable connection or a fixed connection without too many restrictions.

[0104] During operation, the shrink film is passed through multiple support rollers 8 in sequence. When punching, the shrink film does not move, and the bidirectional screw rod 9 is driven to rotate by the stepper motor 10. The bidirectional screw rod 9 drives the two internal threaded sleeves 12 to move away, and the internal threaded sleeve 12 drives the scissor mechanism 3 to shorten through the mounting rod 4 and the guide sleeve 5, so that the scissor mechanism 3 drives the mounting plate 6 to approach the support roller 8 through all the mounting rods 4, and the mounting plate 6 drives the punching needle plate 13 to punch holes in the shrink film on the support roller 8, so that multiple holes can be punched in the shrink film at the same time, thereby improving work efficiency. After completion, the stepper motor 10 is reversed, and the stepper motor 10 drives the bidirectional screw rod 9 to reverse, so that the scissor mechanism 3 is reset, and the scissor mechanism 3 drives the mounting plate 6 to move away from the support roller 8 through the mounting rod 4, and all the punching needle plates 13 leave the shrink film. After the shrink film is driven to move to a set length by external winding and other equipment, the next punching is performed.

[0105] Comparative Example 1

[0106] The difference from Example 3 is that the modified nano-expanded perlite is replaced by ordinary nano-expanded perlite.

[0107] Comparative Example 2

[0108] The difference from Example 3 is that the modified nano-expanded perlite is not contained.

[0109] Comparative Example 3

[0110] The difference from Example 3 is that sodium lignin sulfonate is not contained.

[0111] Comparative Example 4

[0112] The difference from Example 3 is that the modified nano-expanded perlite is replaced by ordinary nano-expanded perlite and sodium lignin sulfonate is not contained.

[0113] Comparative Example 5

[0114] A commercially available heat shrink film.

[0115] The performance tests were performed on the heat shrinkable films of Examples 1-5 and Comparative Examples 1-4. The results are shown in the following table.

[0116]

[0117] From the above results, it can be seen that the heat shrinkable film prepared by the present invention has excellent tensile strength, elongation at break and right-angle tear strength. In particular, by adding modified nano-expanded perlite and sodium lignin sulfonate, the two synergistically enhance the mechanical properties of the heat shrinkable film.

[0118] It should be noted that, for the above-mentioned embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the described order of actions, because according to the present invention, some steps may be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present invention.

[0119] In the several embodiments provided in the present application, it should be understood that the disclosed device can be implemented in other ways. For example, the device embodiments described above are only schematic, such as the division of the above-mentioned units, which is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or communication connection shown or discussed can be through some interfaces, and the indirect coupling or communication connection between devices or units can be in the form of telecommunication or other forms.

[0120] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on these embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field can still combine, add, delete or make other adjustments to the features in the various embodiments of the present invention according to the circumstances without conflict, without making creative work, so as to obtain different other technical solutions that do not deviate from the concept of the present invention in essence, and these technical solutions also belong to the scope of protection of the present invention.

Claims

1. A three-bubble five-layer co-extrusion production process for an easy-to-tear cross-linked heat shrinkable film, characterized in that: include: Prepare raw materials for five membrane layers; After the raw materials of each film layer are mixed evenly, they are added to the five-layer circular extruder for extrusion, and multiple layers are superimposed to form the first film bubble; The first film bubble is subjected to secondary water cooling to obtain a first film body; The first film body is subjected to a three-stage heating treatment, and then inflated by air to form a second film bubble, and then cooled by cold air circulation to obtain a second film body; The second film body is punched with dotted line holes by using a dotted line punching device, and then cross-linked by using an electron beam as a radiation source to obtain the desired easy-tear cross-linked heat shrinkable film; The raw materials of each film layer include, by weight: 50-60 parts of linear low-density polyethylene, 25-35 parts of cyclic polyolefin, 10-15 parts of ethylene-vinyl acetate copolymer, 4-8 parts of modified nano-expanded perlite, 2-4 parts of sodium lignin sulfonate, 2-5 parts of polyurethane acrylate, and 1-3 parts of epoxy soybean oil. The preparation method of the modified nano-expanded perlite is as follows: take the expanded perlite, clean the surface, dry it and then perform preliminary crushing; then place it in a muffle furnace and program the temperature to 600 -700℃, constant temperature roasting for 1-2h, grinding to a particle size of 100-200 mesh after cooling; then adding 25-35vt% hydrochloric acid solution and soaking for 2-4h; filtering to obtain a solid product, putting the solid product into a culture vessel and injecting bacterial cellulose fermentation liquid, wrapping it, and culturing it at 25-30℃ for 3-5 days, rinsing the culture product with deionized water, removing the residual culture liquid, soaking it with deionized water for 3-5h, and finally filtering, drying and grinding to obtain the modified nano expanded perlite.

2. The three-bubble five-layer co-extrusion production process of the easily tearable cross-linked heat shrinkable film according to claim 1, characterized in that: The temperature of the first water cooling in the secondary water cooling forming is 15-20°C, and the temperature of the second water cooling is 20-25°C.

3. The three-bubble five-layer co-extrusion production process of the easily tearable cross-linked heat shrinkable film according to claim 1, characterized in that: The temperatures of the three-stage heating treatment are controlled to be 180-190°C, 150-170°C and 90-110°C respectively.

4. The three-bubble five-layer co-extrusion production process of the easily tearable cross-linked heat shrinkable film according to claim 1, characterized in that: The energy of the electron beam in the cross-linking treatment is 0.5-1.5 MeV, the absorbed dose is 120-140 kGy, and the irradiation speed is 100-120 m / min.

5. The three-bubble five-layer co-extrusion production process of the easily tearable cross-linked heat shrinkable film according to claim 1, characterized in that: By weight, the raw materials of each film layer include: 52-58 parts of linear low-density polyethylene, 28-32 parts of cyclic polyolefin, 11-14 parts of ethylene-vinyl acetate copolymer, 5-7 parts of modified nano-expanded perlite, 2.5-3.5 parts of sodium lignin sulfonate, 3-4 parts of polyurethane acrylate, and 1.5-2.5 parts of epoxy soybean oil.

6. The three-bubble five-layer co-extrusion production process of the easily tearable cross-linked heat shrinkable film according to claim 5, characterized in that: In parts by weight, the raw materials of each film layer include: 55 parts of linear low-density polyethylene, 30 parts of cyclic polyolefin, 12.5 parts of ethylene-vinyl acetate copolymer, 6 parts of modified nano-expanded perlite, 3 parts of sodium lignin sulfonate, 3.5 parts of polyurethane acrylate, and 2 parts of epoxy soybean oil.

7. The three-bubble five-layer co-extrusion production process of the easily tearable cross-linked heat shrinkable film according to claim 1, characterized in that: The preparation method of the bacterial cellulose fermentation liquid is as follows: inoculating Gluconacetobacter species into a culture liquid, the temperature is 25-28°C, the stirring speed is 200-240r / min, and the culture time is 24-36h to obtain a seed liquid; the seed liquid with a volume of 6-10% of the culture liquid is introduced into the culture liquid, mixed and set aside, and the bacterial cellulose fermentation liquid is obtained.

8. The three-bubble five-layer co-extrusion production process of the easily tearable cross-linked heat shrinkable film according to claim 6, characterized in that: The dotted line punching device comprises: A mounting frame, the mounting frame comprising a base plate and a door-shaped frame fixed on the base plate; Two sets of scissor-type mechanisms are installed in the portal frame symmetrically in front and back, and a plurality of support rollers are installed between the two sets of scissor-type mechanisms, and adjacent support rollers are respectively located at both ends of a scissor-type rod; A mounting rod is vertically arranged on the side of the two groups of scissor-fork mechanisms away from the support rollers, a guide sleeve is sleeved on the mounting rod, the guide sleeve is hinged to the end of the scissor-fork mechanism where the support rollers are installed, one end of the mounting rod away from the support rollers is hinged to the end of the scissor-fork mechanism away from the support rollers, a mounting plate is fixed to the end of the mounting rod close to the support rollers, a perforated needle plate is arranged on the side of the mounting plate close to the support rollers, and both ends of the perforated needle plate are fixedly connected to the mounting plate through support rods; A power mechanism for driving the extension and retraction of the scissor mechanism, the power mechanism comprising a stepping motor, a bidirectional screw and an internal threaded sleeve. Bidirectional screws are rotatably installed on both sides of the portal frame and can be rotatably installed through bearings. A stepping motor is fixed on the top of the portal frame to drive a bidirectional screw to rotate. The two bidirectional screws are connected by a transmission structure. Internal threaded sleeves are respectively threaded on the two threaded sections of the bidirectional screw. One of the internal threaded sleeves is connected to an adjacent guide sleeve, and the other internal threaded sleeve is connected to an adjacent mounting rod end.

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