Anti-freezing PE (polyethylene) film, composite film thereof and related preparation method

Abstract

The invention discloses an anti-freezing PE (polyethylene) film, a composite film of the anti-freezing PE film and a related preparation method, relates to the field of packaging films, and aims to solve the problem of low freezing resistance and puncture resistance in the prior art. Comprising anti-freezing layer components: low-density polyethylene, high-density polyethylene, metallocene linear low-density polyethylene resin, cold-resistant PA66 resin, composite phosphate, olefin block copolymer resin, a modified nanoscale silicon oxide coupling agent and a nanoparticle toughening agent, and barrier layer components: low-density polyethylene, linear low-density polyethylene and high-density polyethylene. The toughening heat-sealing layer comprises the following components: low-density polyethylene, sarin resin, metallocene linear low-density polyethylene resin, EVA (Ethylene Vinyl Acetate) modified bonding resin, a slipping agent, a nanoparticle toughening agent, a modified nanoscale silicon oxide coupling agent, dioctyl adipate and an antioxidant. The composite material can resist-38 DEG C ultra-low temperature freezing, and is puncture-resistant, cold-resistant and excellent in barrier property.

Description

Technical Field

[0001] The invention relates to the technical field of packaging films, in particular to an anti-freezing PE film and a composite film thereof and related preparation methods. Background Art

[0002] In the field of flexible packaging, frozen product packaging conditions require rapid freezing at a temperature of -38°C, and storage and transportation at a temperature of -18°C or lower after packaging. Due to the use of ultra-low temperature quick freezing and cold chain storage throughout the process, the product moisture is locked in time to keep it fresh. Frozen food must have the characteristics of long shelf life, not easy to spoil, and keep fresh. Therefore, its packaging material adaptability is required to be high. At present, the common frozen product packaging structures on the market are: BOPP / CPP, BOPP / PE, PA / PE, PA / CPP, PET / CPP, PET / PE, etc.

[0003] Due to the characteristics of CPP and PE materials, they will become brittle and easy to break if they are exposed to low temperature for a long time, and their physical properties will drop sharply and their cold resistance will deteriorate. As the temperature decreases, the plastic will become brittle and easy to break due to the decrease in the activity of its polymer molecular chain. Under the specified impact strength, the plastic will be brittle. If the packaging material used for frozen food has poor cold resistance, the sharp protrusions of the frozen food will easily puncture the packaging during the later transportation and loading and unloading process, causing leakage problems and accelerating the spoilage of the food.

[0004] Chinese patent CN116409038A discloses a frozen food packaging film with long-lasting antibacterial and antiviral functions. The technical solution adopted is that the outer film and the inner film are connected by an adhesive layer. The outer film is composed of a plurality of layers of copolymer nylon film. The copolymer nylon particles are one of PA66 / 6, PA66 / 610 or PA66 / 612 or a combination thereof; the inner film is composed of a plurality of layers of PE film. The raw material of the PE film is metallocene polyethylene.

[0005] Chinese patent CN113715453B discloses a freeze-resistant cast PE film and a preparation method thereof, which discloses 45-55 parts of low-density polyethylene, 4-6 parts of high-density polyethylene, 3-6 parts of polyvinyl alcohol, 3-5 parts of hyperbranched polyamine, 2-4 parts of trehalose, 1-3 parts of sorbitol, 1-3 parts of glycerol, 0.1-2 parts of tackifier, 0.5-2 parts of plasticizer, 0.5-2 parts of lubricant and 1-3 parts of coupling agent;

[0006] The toughened inner layer comprises the following components in parts by weight:

[0007] 25-35 parts of low-density linear polyethylene, 6-8 parts of ethylene-vinyl alcohol copolymer, 5-10 parts of polyethylene grafted maleic anhydride, 1-3 parts of nano-silicon dioxide, 0.5-2 parts of antioxidant, 0.5-2 parts of tackifier and 1-3 parts of coupling agent.

[0008] The above-mentioned existing patents all put some raw materials that can enhance the strength of the antifreeze layer into other layers and then compound them with the antifreeze layer. This method will lead to a decrease in the overall antifreeze and anti-puncture strength of the film.

[0009] Therefore, an ultra-low temperature resistant anti-freezing PE film is developed to improve the anti-freezing performance of the composite film and extend the life cycle of the product packaging. Summary of the invention

[0010] The technical problem to be solved by the present invention is to overcome the existing defects and provide an anti-freezing PE film and its composite film and related preparation method, which can effectively solve the problems in the background technology.

[0011] In order to achieve the above object, the present invention first discloses an anti-freezing PE film, which adopts a technical solution comprising an anti-freezing layer, a barrier layer and a toughening heat-sealing layer, wherein the composition ratio of each layer in parts by weight is as follows:

[0012] The antifreeze layer components include: 30-50 parts of low-density polyethylene, 10-20 parts of high-density polyethylene, 20-35 parts of metallocene linear low-density polyethylene resin, 2-3 parts of cold-resistant PA66 resin, 1-2 parts of composite phosphate, 2-5 parts of olefin block copolymer resin, 1-3 parts of modified nano-scale silicon oxide coupling agent, and 2-3 parts of nanoparticle toughening agent;

[0013] The antifreeze layer can keep the product tough at low temperatures without becoming brittle;

[0014] The barrier layer components: 30-40 parts of low-density polyethylene, 30-40 parts of linear low-density polyethylene, 10-20 parts of high-density polyethylene, and 10-15 parts of polyolefin elastomer;

[0015] The barrier layer can make the film have good barrier properties and ensure the freshness of the product;

[0016] The toughening heat seal layer comprises: 30-45 parts of low-density polyethylene, 10-20 parts of sarling resin, 30-45 parts of metallocene linear low-density polyethylene resin, 3-5 parts of EVA modified adhesive resin, 1-1.5 parts of lubricant, 3-5 parts of nanoparticle toughening agent, 1-3 parts of modified nano-scale silicon oxide coupling agent, 1-3 parts of dioctyl adipate, and 0.5-1 parts of antioxidant;

[0017] The heat-increasing heat-sealing layer can improve the toughness of the film, prevent it from breaking in a low-temperature environment, and facilitate heat-sealing into bags during processing.

[0018] As a preferred technical solution of the present invention, the modified nano-scale silicon oxide coupling agent is modified silicon dioxide; and the nano-particle toughening agent is calcium carbonate.

[0019] The present invention also discloses a method for preparing the above-mentioned low-temperature freezing resistant PE film, and the technical scheme adopted is that the method comprises the following steps:

[0020] Step 1, preparing antifreeze layer blended pellets,

[0021] Weigh olefin block copolymer resin, composite phosphate, cold-resistant PA66 resin, modified nano-scale silicon oxide coupler, nano-particle toughening agent, low-density polyethylene, high-density polyethylene and metallocene linear low-density polyethylene resin according to weight ratio, fully blend and modify the olefin block copolymer resin, composite phosphate, cold-resistant PA66 resin, modified nano-scale silicon oxide coupler, nano-particle toughening agent and low-density polyethylene, and then mix with high-density polyethylene and metallocene linear low-density polyethylene resin to obtain anti-freeze layer blended granules;

[0022] Step 2, preparing barrier layer blended pellets,

[0023] Weigh low-density polyethylene, linear low-density polyethylene, high-density polyethylene, and polyolefin elastomer according to weight ratio, mix them and stir them thoroughly to obtain barrier layer blended pellets;

[0024] Step 3, preparing toughened heat seal layer blended granules,

[0025] Weigh low-density polyethylene, surlyn resin, metallocene linear low-density polyethylene resin, EVA modified adhesive resin, lubricant, nanoparticle toughening agent, modified nano-scale silicon oxide coupling agent, dioctyl adipate, and antioxidant according to weight ratio, fully blend and modify the low-density polyethylene, surlyn resin, EVA modified adhesive resin, nanoparticle toughening agent, modified nano-scale silicon oxide coupling agent, dioctyl adipate, and antioxidant to make granules, then add metallocene linear low-density polyethylene resin and lubricant, and fully stir to obtain toughened heat-sealing layer blended granules;

[0026] Step 4, film making,

[0027] On a three-layer co-extrusion casting machine, the anti-freeze layer blended granules, the barrier layer blended granules and the toughened heat-sealing layer blended granules prepared in steps 1-3 are co-extruded at an interlayer ratio of 1:2:1 to obtain an ultra-low temperature freezing resistant PE film.

[0028] As a preferred technical solution of the present invention, in step 4, the die extrusion temperature of the cast co-extrusion is 230°C, the barrel temperature is 220-230°C, the flow channel temperature is 230°C, and the machine speed is 25m / min.

[0029] The present invention also discloses a composite film based on the above-mentioned low-temperature freezing resistant PE film, and the technical solution adopted is that it comprises a low-temperature freezing resistant PE film layer, an ink layer is connected to the top of the low-temperature freezing resistant PE film layer through a glue layer, and a printing layer is provided on the ink layer;

[0030] The glue layer is a two-component solvent-free polyurethane system glue layer;

[0031] The ink layer is a polyurethane system ink layer;

[0032] The printing layer is a printing-grade biaxially oriented polyamide film.

[0033] The present invention also discloses a method for preparing the composite film, and the technical scheme adopted is comprising the following steps:

[0034] Step a, printing images and texts on the printing layer using a gravure printing process, thereby forming an ink layer;

[0035] Step b, corona treatment of the surface of the anti-cold freezing PE film layer, bonding the printing surface of the printing layer to the corona surface of the anti-cold freezing PE film layer using a glue layer, and sandwiching the ink layer between the anti-cold freezing PE film layer and the printing layer;

[0036] Step c, maturation.

[0037] As a preferred technical solution of the present invention, in the step a, the speed of the printing press during the printing process is 180-250 m / min; and the printing is dried at 65-80°C after printing.

[0038] As a preferred technical solution of the present invention, in the bonding process of step b, the glue cylinder temperature is 40-42°C, the composite temperature is 42°C, and the dry basis glue amount is 1.6-2.0g / m 2 .

[0039] As a preferred technical solution of the present invention, in the step c, the mixture is aged at 40° C. for 36 hours.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention arranges an antifreeze layer, a barrier layer and a toughening sealing layer; in the antifreeze layer, metallocene, cold-resistant PA66, olefin block copolymer resin, etc. are blended with polyethylene, and compared with the prior art that the materials are dispersed into other layers and then stacked, the antifreeze layer has stronger antifreeze performance, ensuring that the long-term storage under low temperature conditions will not become brittle; the barrier layer can ensure the barrier property of the film by arranging different polyethylene and polyolefin elastomers, thereby preventing the packaging bag from leaking while preventing the packaged product from contacting with the outside air, thereby extending the shelf life; the toughening heat-sealing layer can enhance the toughness of the packaging bag, and improve the tensile strength and elongation at break. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of the structure of the anti-freezing PE film of the present invention;

[0042] Figure 2 It is a schematic diagram of the structure of the anti-freezing PE composite film of the present invention.

[0043] In the figure: 1. Anti-low temperature freezing PE film layer; 101. Anti-freezing layer; 102. Barrier layer; 103. Toughened heat sealing layer; 2. Glue layer; 3. Ink layer; 4. Printing layer. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention. Example 1

[0045] This embodiment discloses a first implementation mode of the present invention. Figure 1 As shown, firstly, an antifreeze PE film is disclosed, and the technical scheme adopted is that it includes an antifreeze layer 101, a barrier layer 102 and a toughened heat-sealing layer 103, wherein the antifreeze layer 101 includes 45 parts of low-density polyethylene, 10 parts of high-density polyethylene, 35 parts of metallocene linear low-density polyethylene resin, 2 parts of cold-resistant PA66 resin, 1 part of composite phosphate, 2 parts of olefin block copolymer resin, 3 parts of modified nano-silica coupling agent and 2 parts of calcium carbonate by weight;

[0046] The barrier layer 102 includes 35 parts of low-density polyethylene, 35 parts of linear low-density polyethylene, 15 parts of high-density polyethylene, and 15 parts of polyolefin elastomer by weight;

[0047] The toughened heat seal layer 103 includes, by weight, 38 parts of low-density polyethylene, 15 parts of surin resin, 32.5 parts of metallocene linear low-density polyethylene resin, 5 parts of EVA modified adhesive resin, 1.5 parts of lubricant, 4 parts of calcium carbonate, 2 parts of modified nano-scale silica coupling agent, 2 parts of dioctyl adipate, and 0.5 parts of antioxidant.

[0048] The preparation method of the above-mentioned anti-freezing PE film is as follows:

[0049] Step 1, preparing the antifreeze layer 101 blended pellets,

[0050] Weigh olefin block copolymer resin, composite phosphate, cold-resistant PA66 resin, modified nano-scale silicon oxide coupler, nano-particle toughening agent, low-density polyethylene, high-density polyethylene and metallocene linear low-density polyethylene resin according to weight ratio, fully blend and modify the olefin block copolymer resin, composite phosphate, cold-resistant PA66 resin, modified nano-scale silicon oxide coupler, nano-particle toughening agent and low-density polyethylene, and then mix with high-density polyethylene and metallocene linear low-density polyethylene resin to obtain anti-freeze layer blended granules;

[0051] Step 2, preparing barrier layer 102 blended pellets,

[0052] Weigh low-density polyethylene, linear low-density polyethylene, high-density polyethylene, and polyolefin elastomer according to weight ratio, mix them and stir them thoroughly to obtain barrier layer blended pellets;

[0053] Step 3, preparing the toughened heat seal layer 103 blended granules,

[0054] Weigh low-density polyethylene, surlyn resin, metallocene linear low-density polyethylene resin, EVA modified adhesive resin, lubricant, nanoparticle toughening agent, modified nano-scale silicon oxide coupling agent, dioctyl adipate, and antioxidant according to weight ratio, fully blend and modify the low-density polyethylene, surlyn resin, EVA modified adhesive resin, nanoparticle toughening agent, modified nano-scale silicon oxide coupling agent, dioctyl adipate, and antioxidant to make granules, then add metallocene linear low-density polyethylene resin and lubricant, and fully stir to obtain toughened heat-sealing layer blended granules;

[0055] Step 4, film making,

[0056] On a three-layer co-extrusion casting machine, the anti-freeze layer 101 blended granules, the barrier layer 102 blended granules and the toughened heat-sealing layer 103 blended granules prepared in the steps 1-3 are cast and co-extruded at an interlayer ratio of 1:2:1. The die extrusion temperature of the cast co-extrusion is 230°C, the barrel temperature is 220°C, the flow channel temperature is 230°C, and the machine speed is 25m / min to obtain an ultra-low temperature resistant PE film.

[0057] This embodiment also discloses a composite film based on the above-mentioned low-temperature freezing resistant PE film, such as Figure 2 As shown, the composite film includes a low-temperature freezing resistant PE film layer 1, which is connected to a printing layer 4 of a printing-grade biaxially oriented polyamide film through a glue layer 2 of a two-component solvent-free polyurethane system glue layer, and an ink layer 3 of a polyurethane system is provided between the printing layer 4 and the glue layer 2.

[0058] The preparation method of the above composite film is as follows:

[0059] Step a, printing images and texts on the printing layer 4 by gravure printing process, with the printing machine speed being 250 m / min; drying at 65° C. after printing, thereby forming an ink layer 3;

[0060] Step b, corona treatment of the surface of the anti-low-temperature freezing PE film layer 1, using the glue layer 2 to bond the printed surface of the printing layer 4 to the corona surface of the anti-low-temperature freezing PE film layer 1. During the bonding process, the glue cylinder temperature is 40°C, the composite temperature is 42°C, and the dry basis glue amount is 1.6g / m 2 , sandwiching the ink layer 3 between the low-temperature freezing resistant PE film layer 1 and the printing layer 4;

[0061] Step c, aging at 40° C. for 36 hours to obtain a composite membrane. Example 2

[0062] The difference between this embodiment and embodiment 1 is that the antifreeze layer 101 of an antifreeze PE film includes 30 parts of low-density polyethylene, 20 parts of high-density polyethylene, 20 parts of metallocene linear low-density polyethylene resin, 3 parts of cold-resistant PA66 resin, 2 parts of composite phosphate, 5 parts of olefin block copolymer resin, 1 part of modified nano-silica coupling agent and 3 parts of calcium carbonate by weight;

[0063] The barrier layer 102 includes 30 parts of low-density polyethylene, 30 parts of linear low-density polyethylene, 10 parts of high-density polyethylene, and 10 parts of polyolefin elastomer by weight;

[0064] The toughened heat seal layer 103 includes, by weight, 45 parts of low-density polyethylene, 20 parts of surin resin, 45 parts of metallocene linear low-density polyethylene resin, 3 parts of EVA modified adhesive resin, 1 part of lubricant, 3 parts of calcium carbonate, 1 part of modified nano-scale silica coupling agent, 1 part of dioctyl adipate, and 1 part of antioxidant.

[0065] Regarding the preparation method of the above-mentioned low-temperature freezing resistant PE film, in step 4, the barrel temperature is 230°C.

[0066] In the preparation method of the composite film based on the above-mentioned low-temperature resistant PE film, the printing machine speed in step a is 180m / min, and the printing is dried at 80°C after printing;

[0067] During the bonding process in step b, the glue tank temperature is 42°C and the dry glue amount is 2.0g / m 2 . Example 3

[0068] The difference between this embodiment and embodiment 1 is that an antifreeze layer 101 of an antifreeze PE film includes 50 parts of low-density polyethylene, 15 parts of high-density polyethylene, 25 parts of metallocene linear low-density polyethylene resin, 2.5 parts of cold-resistant PA66 resin, 1.5 parts of composite phosphate, 3.5 parts of olefin block copolymer resin, 2 parts of modified nano-silica coupling agent and 2.5 parts of calcium carbonate by weight;

[0069] The barrier layer 102 includes 40 parts of low-density polyethylene, 40 parts of linear low-density polyethylene, 20 parts of high-density polyethylene, and 12 parts of polyolefin elastomer by weight;

[0070] The toughened heat seal layer 103 includes, by weight, 30 parts of low-density polyethylene, 10 parts of surin resin, 40 parts of metallocene linear low-density polyethylene resin, 4 parts of EVA modified adhesive resin, 1.25 parts of lubricant, 5 parts of calcium carbonate, 3 parts of modified nano-scale silica coupling agent, 3 parts of dioctyl adipate, and 0.75 parts of antioxidant.

[0071] Regarding the preparation method of the above-mentioned low-temperature resistant PE film, in step 4, the barrel temperature is 250°C.

[0072] In the preparation method of the composite film based on the above-mentioned low-temperature resistant PE film, the printing machine speed in step a is 200m / min, and the printing is dried at 70°C after printing;

[0073] During the bonding process in step b, the glue tank temperature is 41°C and the dry glue amount is 1.8g / m 2 .

[0074] Comparing Example 1 with the prior art, the anti-freezing PE film disclosed in Example 1 and the PE film prepared by the prior art with a thickness of 60 μm were prepared, and the toughness and anti-freezing performance were compared. The results are as follows: Table-1 Performance test data of the 60 μm thick anti-freezing PE film prepared in Example 1

[0075] Table-2 Performance test data of 60μm thick PE film produced by existing technology

[0076] The toughness and anti-freezing performance of the composite film prepared in Example 1 were compared with that of the composite film in which the anti-freezing PE film layer 1 was replaced with the anti-freezing film of the prior art. The results are as follows: Table-3 Example 1 Ultra-low temperature resistant NY / PE composite film performance test data

[0077] Table-4 Performance test data of existing NY / PE composite membrane

[0078] Through the above comparison, it can be known that compared with the prior art, the low-temperature freezing resistant PE film layer 1 prepared in this application adds the metallocene linear low-density polyethylene resin that can improve the elongation at break and the olefin block copolymer that can improve the chain winding and film stability to the anti-freezing layer, and the addition of dioctyl adipate in the toughening heat seal layer enables the plasticizer to better enter between the chains, thereby having higher puncture strength and anti-pendulum impact energy, and its tensile strength and elongation at break are higher. Similarly, the composite film prepared based on the low-temperature freezing resistant PE film layer 1 of this application is compared with the composite film prepared by the existing anti-freezing PE film layer, and its puncture strength and anti-pendulum impact energy are also improved, the tensile strength and elongation at break are improved, and the water vapor permeability and oxygen permeability are greatly reduced. The composite film prepared in Example 1 has resistance to ultra-low temperature freezing of -38°C, excellent puncture resistance, cold resistance, and barrier properties, which can greatly maintain the flavor, fragrance, and freshness of the packaged goods, and extend the shelf life of the product, and can be used for plastic flexible packaging such as frozen food and seafood.

[0079] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low temperature and freezing resistant PE film, characterized in that: It comprises an antifreeze layer (101), a barrier layer (102) and a toughened heat-sealing layer (103), and the composition ratio of each layer in parts by weight is as follows: The antifreeze layer (101) comprises: 30-50 parts of low-density polyethylene, 10-20 parts of high-density polyethylene, 20-35 parts of metallocene linear low-density polyethylene resin, 2-3 parts of cold-resistant PA66 resin, 1-2 parts of composite phosphate, 2-5 parts of olefin block copolymer resin, 1-3 parts of modified nano-scale silicon oxide coupling agent, and 2-3 parts of nano-particle toughening agent; The barrier layer (102) comprises: 30-40 parts of low-density polyethylene, 30-40 parts of linear low-density polyethylene, 10-20 parts of high-density polyethylene, and 10-15 parts of polyolefin elastomer; The toughened heat seal layer (103) comprises: 30-45 parts of low-density polyethylene, 10-20 parts of sarling resin, 30-45 parts of metallocene linear low-density polyethylene resin, 3-5 parts of EVA modified adhesive resin, 1-1.5 parts of lubricant, 3-5 parts of nanoparticle toughening agent, 1-3 parts of modified nano-scale silicon oxide coupling agent, 1-3 parts of dioctyl adipate, and 0.5-1 part of antioxidant.

2. The low temperature and freezing resistant PE film according to claim 1, characterized in that: The modified nano-scale silicon oxide coupling agent is modified silicon dioxide; the nano-particle toughening agent is calcium carbonate; the composite phosphate is sodium dihydrogen phosphate; and the antioxidant is phosphite.

3. A method for preparing the low temperature freezing resistant PE film according to claim 1, characterized in that: The following steps are involved: Step 1, preparing an antifreeze layer (101) blended pellets, Weigh olefin block copolymer resin, composite phosphate, cold-resistant PA66 resin, modified nano-scale silicon oxide coupler, nano-particle toughening agent, low-density polyethylene, high-density polyethylene and metallocene linear low-density polyethylene resin according to weight ratio, fully blend and modify the olefin block copolymer resin, composite phosphate, cold-resistant PA66 resin, modified nano-scale silicon oxide coupler, nano-particle toughening agent and low-density polyethylene, and then mix with high-density polyethylene and metallocene linear low-density polyethylene resin to obtain anti-freeze layer blended granules; Step 2, preparing barrier layer (102) blended pellets, Weigh low-density polyethylene, linear low-density polyethylene, high-density polyethylene, and polyolefin elastomer according to weight ratio, mix them and stir them thoroughly to obtain barrier layer blended pellets; Step 3, preparing a toughened heat seal layer (103) blended granules, Weigh low-density polyethylene, surlyn resin, metallocene linear low-density polyethylene resin, EVA modified adhesive resin, lubricant, nanoparticle toughening agent, modified nano-scale silicon oxide coupling agent, dioctyl adipate, and antioxidant according to weight ratio, fully blend and modify the low-density polyethylene, surlyn resin, EVA modified adhesive resin, nanoparticle toughening agent, modified nano-scale silicon oxide coupling agent, dioctyl adipate, and antioxidant to make granules, then add metallocene linear low-density polyethylene resin and lubricant, and fully stir to obtain toughened heat-sealing layer blended granules; Step 4, film making, On a three-layer co-extrusion casting machine, the anti-freeze layer (101) blended pellets, the barrier layer (102) blended pellets and the toughened heat-sealing layer (103) blended pellets prepared in steps 1-3 are co-extruded at an interlayer ratio of 1:2:1 to obtain an ultra-low temperature resistant PE film.

4. The method for preparing the low temperature freezing resistant PE film according to claim 3, characterized in that: In step 4, the die head extrusion temperature of the cast co-extrusion is 230° C., the barrel temperature is 220-230° C., the flow channel temperature is 230° C., and the machine speed is 25 m / min.

5. A composite film based on the low temperature freezing resistant PE film according to claim 1, characterized in that: It comprises a low-temperature freezing resistant PE film layer (1), an ink layer (3) is connected to the top of the low-temperature freezing resistant PE film layer (1) via a glue layer (2), and a printing layer (4) is provided on the ink layer (3); The glue layer (2) is a two-component solvent-free polyurethane system glue layer; The ink layer (3) is a polyurethane system ink layer; The printing layer (4) is a printing-grade biaxially oriented polyamide film.

6. A method for preparing the composite membrane according to claim 5, characterized in that: The following steps are involved: Step a, printing images and texts on the printing layer (4) using a gravure printing process, thereby forming an ink layer (3); Step b, performing corona treatment on the surface of the low-temperature resistant PE film layer (1), bonding the printed surface of the printed layer (4) to the corona surface of the low-temperature resistant PE film layer (1) using a glue layer (2), and sandwiching the ink layer (3) between the low-temperature resistant PE film layer (1) and the printed layer (4); Step c, maturation.

7. The method for preparing a composite membrane according to claim 6, characterized in that: In the step a, the speed of the printing press during the printing process is 180-250 m / min; and the printing is dried at 65-80° C. after printing.

8. The method for preparing a composite membrane according to claim 6, characterized in that: During the bonding process of step b, the glue cylinder temperature is 40-42°C, the compounding temperature is 42°C, and the dry basis glue amount is 1.6-2.0 g / m 2 .

9. The method for preparing a composite membrane according to claim 6, characterized in that: In the step c, the mixture is aged at 40° C. for 36 hours.

Images