A self-adhesive film for stainless steel and preparation method thereof

Abstract

The present invention relates to the field of polymer materials, in particular to a self-adhesive film for stainless steel and a preparation method thereof, which comprises a first PE film layer, an adhesive film layer and a second PE film layer in sequence. The raw materials for preparing the adhesive film layer comprise: castor oil-based polyester polyol, diisocyanate, hydroxy disulfide, alicyclic alcohol chain extender and organic tin catalyst. The self-adhesive film prepared by the present invention has excellent adhesive properties and mechanical properties and can be repeatedly used, especially still showing good adhesive properties on the surface of stainless steel.

Description

Technical Field

[0001] The invention relates to the field of polymer materials, in particular to a self-adhesive film for stainless steel and a preparation method thereof. Background Art

[0002] Self-adhesive film is a film that has adhesive force itself and can be repeatedly attached and detached without a separate adhesive, and is widely used in advertising films, decorative films, protective films for electronic components, etc. Usually, polyethylene, polypropylene, ethylene vinyl acetate, etc. are used as base resins for preparing such self-adhesive films, and tackifiers, plasticizers, etc. are added thereto to give the film adhesion, flexibility, etc., but such self-adhesive films have poor adhesion to stainless steel and are difficult to meet usage requirements. Summary of the invention

[0003] Purpose of the invention: In view of the above technical problems, the present invention provides a self-adhesive film for stainless steel and a preparation method thereof.

[0004] The technical solutions adopted are as follows:

[0005] A self-adhesive film for stainless steel, comprising a first PE film layer, an adhesive film layer, and a second PE film layer in sequence, wherein the raw materials for preparing the adhesive film layer include:

[0006] Castor oil-based polyester polyol, diisocyanate, hydroxy disulfide, alicyclic alcohol chain extender, organic tin catalyst.

[0007] Furthermore, in parts by weight, the raw materials for preparing the adhesive film layer include:

[0008] 60-70 parts of castor oil-based polyester polyol, 8-15 parts of diisocyanate, 2-4 parts of hydroxy disulfide, 1-2 parts of alicyclic alcohol chain extender, and 0.05-0.1 parts of organic tin catalyst.

[0009] Furthermore, the first PE film layer and the second PE film layer are made of the same material, which is a mixture of LDPE and LLDPE in a mass ratio of 1:2-4.

[0010] Furthermore, the preparation method of the castor oil-based polyester polyol is as follows:

[0011] Mix castor oil, small molecule alcohol and sodium hydroxide evenly, heat to 190-220°C under inert gas protection, react for 2-4 hours to obtain an intermediate, mix the intermediate, phthalic anhydride and tetrabutyl titanate evenly, heat to 220-230°C under inert gas protection, keep warm for reaction and measure the acid value, when the acid value of the system reaches 10-15 mgKOH / g, cool to 160-180°C, and when the acid value of the system reaches 1.5-2 mgKOH / g, cool to room temperature.

[0012] Furthermore, the small molecule alcohol is any one of ethylene glycol, glycerol or pentaerythritol.

[0013] Furthermore, the diisocyanate is any one or more combinations of toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, naphthalene diisocyanate or diphenylmethane diisocyanate.

[0014] Furthermore, the diisocyanate is toluene diisocyanate and isophorone diisocyanate, and the mass ratio of the two is 1:1-2.

[0015] Furthermore, the hydroxy disulfide is bis(10-hydroxydecyl) disulfide or bis(11-hydroxyundecyl) disulfide.

[0016] Furthermore, the alicyclic alcohol chain extender is 1,4-cyclohexanediol or hydrogenated bisphenol A.

[0017] The present invention also provides a method for preparing a self-adhesive film for stainless steel:

[0018] S1: Castor oil-based polyester polyol, diisocyanate, hydroxy disulfide and organotin catalyst are mixed, stirred and reacted at 65-70°C for 2-3h to obtain a prepolymer, alicyclic alcohol chain extender is added to the prepolymer, the reaction is continued with stirring for 2-3h, the mixture is quickly stirred and uniformly degassed, and then poured into a mold to obtain an elastomer;

[0019] S2: Add a mixture of LDPE and LLDPE in a mass ratio of 1:2-4, and a mixture of elastomer, LDPE and LLDPE in a mass ratio of 1:2-4 into the outer film hopper, the middle film hopper and the inner film hopper respectively, and extrude each hopper through a three-layer co-extrusion blown film machine. During the extrusion process, the screw temperature of the outer film extrusion mechanism is 170-175°C, and the rotation speed is 35-40rpm. The screw temperature of the middle film extrusion mechanism is 210-220°C, and the rotation speed is 50-60rpm. The screw temperature of the inner film extrusion mechanism is 170-175°C, and the rotation speed is 35-40rpm. The films are then converged into a spiral film blowing die head with a die head temperature of 220-230°C. After extrusion through the die head, the films are stretched and air-cooled at 5-8°C for final shaping.

[0020] Beneficial effects of the present invention:

[0021] The invention provides a self-adhesive film for stainless steel. Castor oil has a low hydroxyl value, poor reactivity, and is easy to shrink after film formation. Therefore, the inventor introduces small molecule alcohol and phthalic anhydride to carry out ester exchange and esterification reaction, thereby improving the reactivity of castor oil and the crosslinking degree during polymerization reaction. Hydroxyl disulfide can introduce long chains and disulfide groups. The disordered winding of the long chains can improve the adhesion of the adhesive film layer. The disulfide groups bring more active sites for the degradation reaction, so that it has better degradation performance. Alicyclic alcohol chain extenders can introduce the alicyclic structure in the molecule into the polyurethane main chain as a transition between the hard segment and the soft segment, so that the segment structure of the polyurethane has better continuity and better mechanical properties. According to tests, the self-adhesive film prepared by the invention has excellent bonding performance and mechanical properties, can be used repeatedly, and can still show good bonding performance on the surface of stainless steel. DETAILED DESCRIPTION

[0022] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0023] Embodiment 1:

[0024] A self-adhesive film for stainless steel, comprising a first PE film layer, an adhesive film layer, and a second PE film layer in sequence, wherein the raw materials for preparing the adhesive film layer include:

[0025] 65 parts of castor oil-based polyester polyol, 5 parts of toluene diisocyanate, 10 parts of isophorone diisocyanate, 3 parts of bis(11-hydroxyundecyl) disulfide, 1 part of hydrogenated bisphenol A, and 0.05 parts of dibutyltin dilaurate.

[0026] Wherein, the preparation method of castor oil-based polyester polyol is as follows:

[0027] Mix castor oil, glycerin and sodium hydroxide in a mass ratio of 1000:200:1 evenly, heat to 220°C under inert gas protection, react for 3 hours to obtain an intermediate, mix the intermediate, phthalic anhydride and tetrabutyl titanate in a mass ratio of 750:100:1 evenly, heat to 230°C under inert gas protection, keep the temperature for reaction and measure the acid value. When the acid value of the system reaches 10.5 mgKOH / g, cool to 180°C. When the acid value of the system reaches 1.5 mgKOH / g, cool to room temperature.

[0028] The present invention also provides a method for preparing a self-adhesive film for stainless steel:

[0029] After weighing the raw materials, castor oil-based polyester polyol, toluene diisocyanate, isophorone diisocyanate, bis(11-hydroxyundecyl) disulfide, and dibutyltin dilaurate were mixed and stirred at 70°C for 3 hours to obtain a prepolymer. Hydrogenated bisphenol A was added to the prepolymer as a chain extender, and the stirring reaction was continued for 3 hours. After rapid stirring and degassing, the mixture was poured into a mold to obtain an elastomer. LDPE and LLDPE were added to the outer film hopper, the middle film hopper, and the inner film hopper in a mass ratio of 1:3. A mixture of mixed materials, elastomers, LDPE and LLDPE in a mass ratio of 1:3 is extruded from each hopper through a three-layer co-extrusion film blowing machine. During the extrusion process, the screw temperature of the outer film extrusion mechanism is 175°C, and the speed is 40rpm. The screw temperature of the middle film extrusion mechanism is 220°C, and the speed is 50rpm. The screw temperature of the inner film extrusion mechanism is 175°C, and the speed is 40rpm. The films are then converged into a spiral film blowing die head with a die head temperature of 230°C. After extrusion through the die head, the films are stretched and air-cooled at 5°C for finalization.

[0030] Embodiment 2:

[0031] A self-adhesive film for stainless steel, comprising a first PE film layer, an adhesive film layer, and a second PE film layer in sequence, wherein the raw materials for preparing the adhesive film layer include:

[0032] 70 parts of castor oil-based polyester polyol, 5 parts of toluene diisocyanate, 10 parts of isophorone diisocyanate, 4 parts of bis(11-hydroxyundecyl) disulfide, 2 parts of hydrogenated bisphenol A, and 0.1 parts of dibutyltin dilaurate.

[0033] Wherein, the preparation method of castor oil-based polyester polyol is as follows:

[0034] Mix castor oil, glycerin and sodium hydroxide in a mass ratio of 1000:200:1 evenly, heat to 220°C under inert gas protection, react for 4 hours to obtain an intermediate, mix the intermediate, phthalic anhydride and tetrabutyl titanate in a mass ratio of 750:100:1 evenly, heat to 230°C under inert gas protection, keep the temperature for reaction and measure the acid value, when the acid value of the system reaches 15 mgKOH / g, cool to 180°C, and when the acid value of the system reaches 2 mgKOH / g, cool to room temperature.

[0035] The present invention also provides a method for preparing a self-adhesive film for stainless steel:

[0036] S1: After weighing the raw materials, castor oil-based polyester polyol, toluene diisocyanate, isophorone diisocyanate, bis(11-hydroxyundecyl) disulfide, and dibutyltin dilaurate were mixed, and stirred for reaction at 70° C. for 3 h to obtain a prepolymer, and hydrogenated bisphenol A was added to the prepolymer as a chain extender, and the stirring reaction was continued for 3 h. After rapid stirring and degassing, the mixture was poured into a mold to obtain an elastomer;

[0037] S2: Add a mixture of LDPE and LLDPE in a mass ratio of 1:3, and a mixture of elastomer, LDPE and LLDPE in a mass ratio of 1:3 into the outer film hopper, the middle film hopper and the inner film hopper respectively, and extrude each hopper through a three-layer co-extrusion blown film machine. During the extrusion process, the screw temperature of the outer film extrusion mechanism is 175°C and the speed is 40rpm, the screw temperature of the middle film extrusion mechanism is 220°C and the speed is 60rpm, and the screw temperature of the inner film extrusion mechanism is 175°C and the speed is 40rpm. The films are then converged into a spiral film blowing die head with a die head temperature of 230°C, stretched after extrusion through the die head, and air-cooled at 8°C for shaping.

[0038] Embodiment 3:

[0039] A self-adhesive film for stainless steel, comprising a first PE film layer, an adhesive film layer, and a second PE film layer in sequence, wherein the raw materials for preparing the adhesive film layer include:

[0040] 60 parts of castor oil-based polyester polyol, 5 parts of toluene diisocyanate, 10 parts of isophorone diisocyanate, 2 parts of bis(11-hydroxyundecyl) disulfide, 1 part of hydrogenated bisphenol A, and 0.05 parts of dibutyltin dilaurate.

[0041] Wherein, the preparation method of castor oil-based polyester polyol is as follows:

[0042] Mix castor oil, glycerin and sodium hydroxide in a mass ratio of 1000:200:1 evenly, heat to 190°C under inert gas protection, react for 2 hours to obtain an intermediate, mix the intermediate, phthalic anhydride and tetrabutyl titanate in a mass ratio of 750:100:1 evenly, heat to 220°C under inert gas protection, keep the temperature for reaction and measure the acid value. When the acid value of the system reaches 10 mgKOH / g, cool to 160°C. When the acid value of the system reaches 1.5 mgKOH / g, cool to room temperature.

[0043] The present invention also provides a method for preparing a self-adhesive film for stainless steel:

[0044] S1: After weighing the raw materials, castor oil-based polyester polyol, toluene diisocyanate, isophorone diisocyanate, bis(11-hydroxyundecyl) disulfide, and dibutyltin dilaurate were mixed, and stirred at 65° C. for 2 h to obtain a prepolymer, and hydrogenated bisphenol A was added to the prepolymer as a chain extender, and the stirring reaction was continued for 2 h. After rapid stirring and degassing, the mixture was poured into a mold to obtain an elastomer;

[0045] S2: Add a mixture of LDPE and LLDPE in a mass ratio of 1:3, and a mixture of elastomer, LDPE and LLDPE in a mass ratio of 1:3 into the outer film hopper, the middle film hopper and the inner film hopper respectively, and extrude each hopper through a three-layer co-extrusion blown film machine. During the extrusion process, the screw temperature of the outer film extrusion mechanism is 170°C and the speed is 35rpm, the screw temperature of the middle film extrusion mechanism is 210°C and the speed is 50rpm, and the screw temperature of the inner film extrusion mechanism is 170°C and the speed is 35rpm. The films are then converged into a spiral film blowing die head with a die head temperature of 220°C, stretched after extrusion through the die head, and air-cooled at 5°C for shaping.

[0046] Embodiment 4:

[0047] A self-adhesive film for stainless steel, comprising a first PE film layer, an adhesive film layer, and a second PE film layer in sequence, wherein the raw materials for preparing the adhesive film layer include:

[0048] 65 parts of castor oil-based polyester polyol, 15 parts of isophorone diisocyanate, 3 parts of bis(11-hydroxyundecyl) disulfide, 1 part of hydrogenated bisphenol A, and 0.05 parts of dibutyltin dilaurate.

[0049] Wherein, the preparation method of castor oil-based polyester polyol is as follows:

[0050] Mix castor oil, glycerin and sodium hydroxide in a mass ratio of 1000:200:1 evenly, heat to 220°C under inert gas protection, react for 3 hours to obtain an intermediate, mix the intermediate, phthalic anhydride and tetrabutyl titanate in a mass ratio of 750:100:1 evenly, heat to 230°C under inert gas protection, keep the temperature for reaction and measure the acid value. When the acid value of the system reaches 10.5 mgKOH / g, cool to 180°C. When the acid value of the system reaches 1.5 mgKOH / g, cool to room temperature.

[0051] The present invention also provides a method for preparing a self-adhesive film for stainless steel:

[0052] After weighing the raw materials, castor oil-based polyester polyol, isophorone diisocyanate, bis(11-hydroxyundecyl) disulfide, and dibutyltin dilaurate were mixed and stirred at 70°C for 3 hours to obtain a prepolymer. Hydrogenated bisphenol A was added to the prepolymer as a chain extender, and the stirring reaction was continued for 3 hours. After rapid stirring and degassing, the mixture was poured into a mold to obtain an elastomer. A mixture of LDPE and LLDPE in a mass ratio of 1:3 was added to the outer film hopper, the middle film hopper, and the inner film hopper, respectively. A mixture of elastomer, LDPE and LLDPE in a mass ratio of 1:3 is extruded from each hopper through a three-layer co-extrusion film blowing machine. During the extrusion process, the screw temperature of the outer film extrusion mechanism is 175°C, and the speed is 40rpm, the screw temperature of the middle film extrusion mechanism is 220°C, and the speed is 50rpm, and the screw temperature of the inner film extrusion mechanism is 175°C, and the speed is 40rpm. The materials are then converged into a spiral film blowing die with a die head temperature of 230°C, stretched after extrusion through the die head, and air-cooled at 5°C for shaping.

[0053] The method is substantially the same as Example 1, except that isophorone diisocyanate is used alone.

[0054] Embodiment 5:

[0055] A self-adhesive film for stainless steel, comprising a first PE film layer, an adhesive film layer, and a second PE film layer in sequence, wherein the raw materials for preparing the adhesive film layer include:

[0056] 65 parts of castor oil-based polyester polyol, 15 parts of toluene diisocyanate, 3 parts of bis(11-hydroxyundecyl) disulfide, 1 part of hydrogenated bisphenol A, and 0.05 parts of dibutyltin dilaurate.

[0057] Wherein, the preparation method of castor oil-based polyester polyol is as follows:

[0058] Mix castor oil, glycerin and sodium hydroxide in a mass ratio of 1000:200:1 evenly, heat to 220°C under inert gas protection, react for 3 hours to obtain an intermediate, mix the intermediate, phthalic anhydride and tetrabutyl titanate in a mass ratio of 750:100:1 evenly, heat to 230°C under inert gas protection, keep the temperature for reaction and measure the acid value. When the acid value of the system reaches 10.5 mgKOH / g, cool to 180°C. When the acid value of the system reaches 1.5 mgKOH / g, cool to room temperature.

[0059] The present invention also provides a method for preparing a self-adhesive film for stainless steel:

[0060] After weighing the raw materials, castor oil-based polyester polyol, toluene diisocyanate, bis(11-hydroxyundecyl) disulfide and dibutyltin dilaurate were mixed, and the mixture was stirred and reacted at 70°C for 3 hours to obtain a prepolymer. Hydrogenated bisphenol A was added to the prepolymer as a chain extender, and the stirring reaction was continued for 3 hours. After rapid stirring and degassing, the mixture was poured into a mold to obtain an elastomer. A mixture of LDPE and LLDPE in a mass ratio of 1:3 was added to the outer film hopper, the middle film hopper and the inner film hopper, respectively. A mixture of elastomer, LDPE and LLDPE in a mass ratio of 1:3 is extruded from each hopper through a three-layer co-extrusion film blowing machine. During the extrusion process, the screw temperature of the outer film extrusion mechanism is 175°C, and the speed is 40rpm. The screw temperature of the middle film extrusion mechanism is 220°C, and the speed is 50rpm. The screw temperature of the inner film extrusion mechanism is 175°C, and the speed is 40rpm. The materials are then converged into a spiral film blowing die head with a die head temperature of 230°C. After being extruded through the die head, they are stretched and air-cooled at 5°C for shaping.

[0061] The method is basically the same as Example 1, except that toluene diisocyanate is used alone.

[0062] Embodiment 6:

[0063] A self-adhesive film for stainless steel, comprising a first PE film layer, an adhesive film layer, and a second PE film layer in sequence, wherein the raw materials for preparing the adhesive film layer include:

[0064] 65 parts of castor oil-based polyester polyol, 5 parts of toluene diisocyanate, 10 parts of isophorone diisocyanate, 3 parts of bis(10-hydroxydecyl) disulfide, 1 part of hydrogenated bisphenol A, and 0.05 parts of dibutyltin dilaurate.

[0065] Wherein, the preparation method of castor oil-based polyester polyol is as follows:

[0066] Mix castor oil, glycerin and sodium hydroxide in a mass ratio of 1000:200:1 evenly, heat to 220°C under inert gas protection, react for 3 hours to obtain an intermediate, mix the intermediate, phthalic anhydride and tetrabutyl titanate in a mass ratio of 750:100:1 evenly, heat to 230°C under inert gas protection, keep the temperature for reaction and measure the acid value. When the acid value of the system reaches 10.5 mgKOH / g, cool to 180°C. When the acid value of the system reaches 1.5 mgKOH / g, cool to room temperature.

[0067] The present invention also provides a method for preparing a self-adhesive film for stainless steel:

[0068] After weighing the raw materials, castor oil-based polyester polyol, toluene diisocyanate, isophorone diisocyanate, bis(10-hydroxydecyl) disulfide, and dibutyltin dilaurate were mixed and stirred at 70°C for 3 hours to obtain a prepolymer. Hydrogenated bisphenol A was added to the prepolymer as a chain extender, and the stirring reaction was continued for 3 hours. After rapid stirring and degassing, the mixture was poured into a mold to obtain an elastomer. LDPE and LLDPE in a mass ratio of 1:3 were added to the outer film hopper, the middle film hopper, and the inner film hopper, respectively. A mixture of compound, elastomer, LDPE and LLDPE in a mass ratio of 1:3 is extruded from each hopper through a three-layer co-extrusion film blowing machine. During the extrusion process, the screw temperature of the outer film extrusion mechanism is 175°C, and the speed is 40rpm, the screw temperature of the middle film extrusion mechanism is 220°C, and the speed is 50rpm, and the screw temperature of the inner film extrusion mechanism is 175°C, and the speed is 40rpm. The mixture flows into a spiral film blowing die with a die head temperature of 230°C, is stretched after extrusion through the die head, and is air-cooled at 5°C for shaping.

[0069] The method is substantially the same as Example 1, except that bis(11-hydroxyundecyl)disulfide is replaced by bis(10-hydroxydecyl)disulfide.

[0070] Comparative Example 1

[0071] Comparative Example 1 is substantially the same as Example 1, except that bis(11-hydroxyundecyl) disulfide is not added.

[0072] Comparative Example 2

[0073] Comparative Example 2 is substantially the same as Example 1, except that castor oil is directly used as the polyol.

[0074] Performance Testing:

[0075] The shear bonding strength test of the adhesive film layer was performed separately: the adhesive film layers in Examples 1-6 of the present invention and Comparative Examples 1-2 were cut into 1 cm×1 cm specimens, respectively, and bonded to the surface of 304 stainless steel material. After applying a uniform load of 5 N for 10 seconds, the surfaces were bonded together, and the shear bonding strength was tested in the shear direction using an electronic universal testing machine.

[0076] Repeated bonding test: Repeat the bonding between the adhesive film layer and the surface of the 304 stainless steel material for 50 times, and use an electronic universal testing machine to test the shear bonding strength. Observe the change of shear bonding strength with the number of tests. The test method is consistent with the test method of shear adhesion strength. Calculate the decrease rate of shear bonding strength after 50 repeated bondings.

[0077] Mechanical property test: Instron 5965 universal material testing machine was used to test the tensile stress and strain of the self-adhesive films in Examples 1-6 of the present invention and Comparative Examples 1-2. The specimens were dumbbell-shaped, the cutting knife size adopted the national standard GB / T9865.1 / 3, and the test process adopted a pneumatic clamp. The tensile rate was 500 mm / min. At least 5 groups were tested for each system, and the average value of the final result after the test was taken.

[0078] The above test results are shown in Table 1 below:

[0079] Table 1:

[0080]

[0081]

[0082] It can be seen from Table 1 above that the self-adhesive film prepared by the present invention has excellent bonding properties and mechanical properties and can be used repeatedly, especially on stainless steel surfaces.

[0083] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-adhesive film for stainless steel, characterized in that: The first PE film layer, the adhesive film layer and the second PE film layer are sequentially included, and the raw materials for preparing the adhesive film layer include, by weight: 60-70 parts of castor oil-based polyester polyol, 8-15 parts of diisocyanate, 2-4 parts of hydroxy disulfide, 1-2 parts of alicyclic alcohol chain extender, 0.05-0.1 parts of organotin catalyst; The first PE film layer and the second PE film layer are made of the same material, which is a mixture of LDPE and LLDPE in a mass ratio of 1:2-4; The preparation method of the castor oil-based polyester polyol is as follows: Mix castor oil, small molecule alcohol and sodium hydroxide evenly, heat to 190-220°C under inert gas protection, react for 2-4 hours to obtain an intermediate, mix the intermediate, phthalic anhydride and tetrabutyl titanate evenly, heat to 220-230°C under inert gas protection, keep warm for reaction and measure the acid value, when the acid value of the system reaches 10-15 mgKOH / g, cool to 160-180°C, and when the acid value of the system reaches 1.5-2 mgKOH / g, cool to room temperature; The small molecule alcohol is any one of ethylene glycol, glycerol or pentaerythritol; The diisocyanate is a combination of toluene diisocyanate and isophorone diisocyanate, and the mass ratio of the two is 1:1-2; The hydroxy disulfide is bis(10-hydroxydecyl) disulfide or bis(11-hydroxyundecyl) disulfide; The alicyclic alcohol chain extender is 1,4-cyclohexanediol or hydrogenated bisphenol A; The preparation method of the self-adhesive film for stainless steel is as follows: S1: Castor oil-based polyester polyol, diisocyanate, hydroxy disulfide and organotin catalyst are mixed, stirred and reacted at 65-70°C for 2-3h to obtain a prepolymer, alicyclic alcohol chain extender is added to the prepolymer, the reaction is continued with stirring for 2-3h, the mixture is quickly stirred and uniformly degassed, and then poured into a mold to obtain an elastomer; S2: Add a mixture of LDPE and LLDPE in a mass ratio of 1:2-4 to the outer film hopper, add an elastomer to the middle film hopper, add a mixture of LDPE and LLDPE in a mass ratio of 1:2-4 to the inner film hopper, and extrude each hopper through a three-layer co-extrusion blown film machine. During the extrusion process, the screw temperature of the outer film extrusion mechanism is 170-175℃, and the rotation speed is 35-40rpm. The screw temperature of the middle film extrusion mechanism is 210-220℃, and the rotation speed is 50-60rpm. The screw temperature of the inner film extrusion mechanism is 170-175℃, and the rotation speed is 35-40rpm. The films are then converged to a spiral film blowing die head with a die head temperature of 220-230℃. After extrusion through the die head, the films are stretched and air-cooled at 5-8℃ for final shaping.

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