A four-layer film for infusion and a method for preparing the same

Abstract

The application belongs to the technical field of infusion bag films, and provides a four-layer infusion film, which comprises an outer layer, a secondary outer layer, a middle layer and an inner layer.The outer layer comprises the following raw material components and weight fractions: 20-35 parts of nano zinc oxide and 50-80 parts of amino acrylate.The secondary outer layer comprises the following raw material components and weight fractions: 70-90 parts of homopolymer polypropylene and 10-30 parts of elastomer.The middle layer comprises the following raw material components and weight fractions: 20-40 parts of copolymer polypropylene, 40-60 parts of elastomer and 10-20 parts of cyclic olefin copolymer.The inner layer comprises the following raw material components and weight fractions: 60-80 parts of binary copolymer polypropylene, 20-40 parts of elastomer and 1-3 parts of chitosan.The application can sufficiently improve the bonding strength of nano zinc oxide and the film surface of the outer layer, and the adhesion is strong, thereby achieving the effect of long-term antibacterial property.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of infusion bag films, and particularly relates to a four-layer infusion film and a preparation method thereof. BACKGROUND

[0002] Although traditional infusion bottles have the advantages of low cost and good compatibility with drugs, they have the disadvantages of large quality, large volume, difficult transportation and fragility. Plastic bottles solve the problems of the glass bottles to some extent, but in the use process, the liquid needs to be added with internal pressure to drip out, which increases the risk of secondary pollution. Further, PVC soft bags are born at the historic moment, but the PVC material contains polyvinyl chloride monomer, which is not conducive to human health. At the same time, the plasticizer diethyl phthalate (DEHP) in the PVC material is easy to precipitate, and along with the drug solution into the human body, it causes damage to the human body.

[0003] Therefore, in the prior art, non-PVC soft bags are used to solve the above problems of PVC soft bags. For example, a new three-layer co-extrusion infusion bag film is disclosed in the patent with the publication number CN202716491U. Specifically, the patent discloses an infusion film bag film prepared by a three-layer co-extrusion process, the main material of which is polypropylene or modified polypropylene. The film has high transparency and will not turn white during sterilization and use, and has good sterilization adaptability.

[0004] However, although the non-PVC soft bag in the prior art has good mechanical properties and stable physicochemical properties, and solves the technical problem of the need to use plasticizers in PVC materials, it still has the defects of high water vapor permeability and insufficient antibacterial performance, like other multi-layer co-extrusion infusion films currently used in China. Therefore, it still cannot guarantee the stability of most drugs and the safety of drug use.

[0005] Therefore, based on the above description, there is an urgent need for a multi-layer co-extrusion infusion film with strong water vapor barrier ability and good antibacterial performance. SUMMARY

[0006] In view of the above deficiencies in the prior art, the first purpose of the present application is to provide a four-layer infusion film with strong water vapor barrier ability and good antibacterial performance, which guarantees the safety and stability during drug use.

[0007] The application is achieved by the following technical solutions:

[0008] A four-layer infusion film, comprising an outer layer, a sub-outer layer, a middle layer and an inner layer,

[0009] The outer layer comprises the following raw material components and weight fractions: 20-35 parts of nano-zinc oxide, 50-80 parts of amino acrylate;

[0010] The secondary outer layer comprises the following raw material components and weight fractions: homopolymer polypropylene 70-90 parts, elastomer 10-30 parts;

[0011] The middle layer comprises the following raw material components and weight fractions: copolymer polypropylene 20-40 parts, elastomer 40-60 parts, cyclic olefin copolymer 10-20 parts;

[0012] The inner layer comprises the following raw material components and weight fractions: binary copolymer polypropylene 60-80 parts, elastomer 20-40 parts, chitosan 1-3 parts.

[0013] The binary copolymer polypropylene can also be replaced by ternary copolymer polypropylene.

[0014] In the outermost layer formula, the amino acrylate can provide an active group of amino for grafting nano zinc oxide, and the acrylate group therein can provide certain viscosity, so that the nano zinc oxide can be quickly bonded to the surface of the outer layer film, thereby sufficiently improving the stability of the nano zinc oxide.

[0015] In the middle layer formula, the added cyclic olefin copolymer has excellent properties such as high strength, high transparency, water vapor barrier property, and chemical inertness, but when used as a packaging material, the hardness is too large to be used alone. Further, the cyclic olefin copolymer is used in blending with polypropylene and elastomer, which not only solves the molding problem of pure cyclic olefin copolymer, but also improves the thermal stability, water vapor barrier property, and other properties of the blended material without increasing the barrier layer.

[0016] In the inner layer formula system, the natural and harmless biological antibacterial agent chitosan is added. Chitosan has good biocompatibility and biological activity, and does not harm the efficacy of drugs or the human body. By blending chitosan, polypropylene and elastomer, not only the production process is simple, but also the inner layer material is endowed with certain antibacterial properties, thereby ensuring the safety and stability of infusion drugs during use.

[0017] Further, the elastomer is at least one of styrene-ethylene-butylene-styrene block copolymer, styrene-ethylene-propylene-styrene copolymer, and polyolefin elastomer.

[0018] Further, the thickness of the outer layer is 1-10 μm.

[0019] Further, the thickness of the secondary outer layer is 20-30 μm.

[0020] Further, the thickness of the middle layer is 120-160 μm.

[0021] Further, the thickness of the inner layer is 20-40 μm.

[0022] Further, the total thickness of the infusion film is 190-220 μm.

[0023] A second object of the present application is to provide a preparation method of the four-layer infusion film, comprising the following steps:

[0024] S1 adopts a three-layer co-extrusion under-blowing water-cooling blown film processing technology, uniformly mixes the outer layer raw material, the middle layer raw material and the inner layer raw material according to the corresponding mass ratio, puts them into a co-extrusion blown film machine for co-extrusion blown film, and then sequentially performs water ring cooling and winding into a cylindrical film to obtain a composite film;

[0025] S2 sprays amino acrylate on the outer surface of the composite film, and then uniformly screens the nano zinc oxide on the surface of the amino acrylate coating under ultrasonic vibration to obtain a pre-fabricated film;

[0026] S3 places the pre-fabricated film in an oxygen atmosphere for irradiation treatment, and after standing for 1-5 min, dries to obtain an infusion film.

[0027] The amino acrylate contains amino and acrylate groups in the molecule, thereby having the active group of amino and the adhesion property of acrylate. After spraying, the amino acrylate can be quickly adhered to the surface of the outer film. Then, the nano zinc oxide is screened on the surface of the amino acrylate coating by ultrasonic vibration. The amino acrylate can quickly bond the nano zinc oxide particles, and under the condition of vibration, the nano zinc oxide particles are uniformly embedded or immersed in the amino acrylate. Further, under the oxygen atmosphere, irradiation treatment is performed. After the rays pass through the amino acrylate, the nano zinc oxide layer and the outer film material, active groups such as hydroxyl, carboxyl and amide groups on the surface of the outer film material react with the amino active group in the amino acrylate, so that the nano zinc oxide is stably grafted on the surface of the outer film.

[0028] Further, in step S1, the secondary outer layer extrusion temperature is 190-210°C, the middle layer extrusion temperature is 180-210°C, and the inner layer extrusion temperature is 190-200°C.

[0029] Further, in step S2, the ultrasonic frequency range is 30-40 KHz, and the aperture of the vibration screen is 20-30 nm.

[0030] Further, in step S3, the radiation source is a cobalt-60 gamma ray, the irradiation dose is 2-10 Gy, and the irradiation dose rate is 10 Gy / min.

[0031] The present application has the following beneficial effects:

[0032] (1) by adding amino acrylate in the outer layer formula, can play the role of providing amino active group grafting nano zinc oxide, at the same time, the acrylate group in it can provide certain viscosity, and then make the nano zinc oxide and the film surface of the outer layer combination strength high, strong adhesion, can long keep antibacterial effect.

[0033] (2) the cycloolefin copolymer is used by blending with polypropylene and elastomer, not only can increase the forming problem of pure cycloolefin copolymer, but also can improve the water vapor barrier performance of the blended material without increasing the barrier layer.

[0034] (3) by blending chitosan, polypropylene and elastomer, not only the production process is simple, but also can endow the inner layer material with certain antibacterial property, ensure the safety and stability of infusion drugs in use. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments, it should be understood that the following drawings only show some embodiments of the present application, therefore should not be regarded as the limitation to the scope, for those skilled in the art, without paying the creative labor, can also obtain other related drawings according to these drawings.

[0036] Figure 1 For the cross section structure schematic diagram of part of the film layer of the embodiments of the present application.

[0037] Figure legend: 1-outer layer, 2-secondary outer layer, 3-middle layer, 4-inner layer. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be described clearly and completely below. The specific conditions are not marked in the embodiments, according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used are not marked by the manufacturer, which are conventional products that can be purchased in the market.

[0039] EMBODIMENT

[0040] EMBODIMENT 1

[0041] The embodiment provides a four-layer transfusion film, (1) an outer layer material and components thereof, wherein nano-zinc oxide is 20 parts by weight, amino acrylate is 80 parts by weight, and the thickness is 5 microns; (2) a secondary outer layer material and components thereof, wherein homopolymer polypropylene is 90 parts by weight, styrene-ethylene-butylene-styrene block copolymer is 10 parts by weight, and the thickness is 25 microns; (3) a middle layer material and components thereof, wherein copolymer polypropylene is 30 parts by weight, styrene-ethylene-butylene-styrene block copolymer is 60 parts by weight, and cycloolefin copolymer is 10 parts by weight, and the thickness is 145 microns; (4) an inner layer material and components thereof, wherein binary polypropylene is 60 parts by weight, styrene-ethylene-butylene-styrene block copolymer is 37 parts by weight, and chitosan is 3 parts by weight, and the thickness is 20 microns; (5) the granules are uniformly mixed according to the foregoing formula, a three-layer co-extrusion film blowing machine is used, the die head temperature is ensured to be 180-210 DEG C, melt extrusion is carried out, film blowing is carried out by blowing downwards, and then water ring cooling and winding into a cylinder film are carried out, so that a composite film is obtained; further, 65 parts of amino acrylate is sprayed on the outer layer surface of the composite film by using a high-pressure airless spraying mode, then 20 parts of nano-zinc oxide dry powder is uniformly sieved on the surface of the amino acrylate coating by using an ultrasonic vibration sieve with a pore size of 25 nm under a frequency of 35 KHz, so that a prefabricated film is obtained; the prefabricated film is placed in an oxygen atmosphere, and irradiation treatment is carried out, a radiation source is cobalt-60 gamma rays, an irradiation dose is 2 Gy, an irradiation dose rate is 10 Gy / min, after standing for 1 min, air blowing drying is carried out, and a transfusion film is obtained.

[0042] Example 2

[0043] The embodiment provides a four-layer transfusion film, (1) an outer layer material and components thereof, in terms of weight fraction, 23 parts of nano-zinc oxide, 77 parts of amino acrylate, and a thickness of 5 μm; (2) a secondary outer layer material and components thereof, in terms of weight fraction, 90 parts of homopolymer polypropylene, 10 parts of styrene-ethylene-butylene-styrene block copolymer, and a thickness of 25 μm; (3) a middle layer material and components thereof, in terms of weight fraction, 30 parts of copolymer polypropylene, 60 parts of styrene-ethylene-butylene-styrene block copolymer, and 10 parts of cyclic olefin copolymer, and a thickness of 150 μm; (4) an inner layer material and components thereof, in terms of weight fraction, 60 parts of binary polypropylene, 37 parts of styrene-ethylene-butylene-styrene block copolymer, and 3 parts of chitosan, and a thickness of 20 μm; (5) the granules are uniformly mixed according to the foregoing formula, a three-layer co-extrusion film blowing machine is used, the die head temperature is ensured to be 180-210 ℃, melt extrusion is performed, film blowing is performed, and then water ring cooling and winding into a cylinder film are sequentially performed, so that a composite film is obtained; further, in terms of weight fraction, 65 parts of amino acrylate is sprayed on the outer layer surface of the composite film by using a high-pressure airless spraying mode, then 23 parts of nano-zinc oxide dry powder is uniformly sieved on the surface of the amino acrylate coating by using an ultrasonic vibration sieve with a pore size of 25 nm at a frequency of 35 KHz, so that a prefabricated film is obtained; the prefabricated film is placed in an oxygen atmosphere, and irradiation treatment is performed, a radiation source is cobalt-60 gamma rays, an irradiation dose is 2 Gy, an irradiation dose rate is 10 Gy / min, after standing for 1 min, air blowing drying is performed, and a transfusion film is obtained.

[0044] Example 3

[0045] The embodiment provides a four-layer transfusion film, (1) an outer layer material and components thereof, wherein nano-zinc oxide is 26 parts by weight, amino acrylate is 74 parts by weight, and the thickness is 5 microns; (2) a secondary outer layer material and components thereof, wherein homopolymer polypropylene is 90 parts by weight, styrene-ethylene-butylene-styrene block copolymer is 10 parts by weight, and the thickness is 25 microns; (3) a middle layer material and components thereof, wherein copolymer polypropylene is 30 parts by weight, styrene-ethylene-butylene-styrene block copolymer is 60 parts by weight, and cycloolefin copolymer is 10 parts by weight, and the thickness is 150 microns; (4) an inner layer material and components thereof, wherein binary polypropylene is 60 parts by weight, styrene-ethylene-butylene-styrene block copolymer is 37 parts by weight, and chitosan is 3 parts by weight, and the thickness is 25 microns; (5) the granules are uniformly mixed according to the foregoing formula, a three-layer co-extrusion film blowing machine is used, the die head temperature is ensured to be 180-210 DEG C, melt extrusion is carried out, film blowing is carried out by blowing downwards, and then water ring cooling and winding into a cylinder film are carried out, so that a composite film is obtained; further, 65 parts of amino acrylate is sprayed on the outer layer surface of the composite film by using a high-pressure airless spraying mode, then 26 parts of nano-zinc oxide dry powder is uniformly sieved on the surface of the amino acrylate coating by using an ultrasonic vibration sieve with a pore size of 25 nm under a frequency of 35 KHz, so that a prefabricated film is obtained; the prefabricated film is placed in an oxygen atmosphere, and irradiation treatment is carried out, a radiation source is cobalt-60 gamma rays, an irradiation dose is 2 Gy, an irradiation dose rate is 10 Gy / min, after standing for 1 min, air blowing drying is carried out, and a transfusion film is obtained.

[0046] Example 4

[0047] The embodiment provides a four-layer transfusion film, (1) an outer layer raw material and components thereof, in terms of weight fraction, 29 parts of nano-zinc oxide, 71 parts of amino acrylate, and a thickness of 5 μm; (2) a secondary outer layer raw material and components thereof, in terms of weight fraction, 90 parts of homopolymer polypropylene, 10 parts of styrene-ethylene-butylene-styrene block copolymer, and a thickness of 25 μm; (3) a middle layer raw material and components thereof, in terms of weight fraction, 30 parts of copolymer polypropylene, 60 parts of styrene-ethylene-butylene-styrene block copolymer, and 10 parts of cyclic olefin copolymer, and a thickness of 155 μm; (4) an inner layer raw material and components thereof, in terms of weight fraction, 60 parts of binary polypropylene, 37 parts of styrene-ethylene-butylene-styrene block copolymer, and 3 parts of chitosan, and a thickness of 25 μm; (5) the pellets are uniformly mixed according to the foregoing formula, a three-layer co-extrusion film blowing machine is used, the die head temperature is ensured to be 180-210 ℃, melt extrusion is performed, film blowing is performed by downward blowing, and then water ring cooling and winding into a cylinder film are sequentially performed, so that a composite film is obtained; further, in terms of weight fraction, 65 parts of amino acrylate is sprayed on the outer layer surface of the composite film by using a high-pressure airless spraying mode, then 29 parts of nano-zinc oxide dry powder is uniformly sieved on the surface of the amino acrylate coating by using an ultrasonic vibration sieve with a pore size of 25 nm at a frequency of 35 KHz, so that a prefabricated film is obtained; the prefabricated film is placed in an oxygen atmosphere, and irradiation treatment is performed, a radiation source is cobalt-60 gamma rays, an irradiation dose is 2 Gy, an irradiation dose rate is 10 Gy / min, after standing for 1 min, air blowing drying is performed, and thus a transfusion film is obtained.

[0048] Example 5

[0049] The embodiment provides a four-layer transfusion film, (1) an outer layer material and components thereof, in terms of weight fractions, 32 parts of nano-zinc oxide, 68 parts of amino acrylate, and a thickness of 5 microns; (2) a secondary outer layer material and components thereof, in terms of weight fractions, 90 parts of homopolymer polypropylene, 10 parts of styrene-ethylene-butylene-styrene block copolymer, and a thickness of 25 microns; (3) a middle layer material and components thereof, in terms of weight fractions, 30 parts of copolymer polypropylene, 60 parts of styrene-ethylene-butylene-styrene block copolymer, and 10 parts of cyclic olefin copolymer, and a thickness of 155 microns; (4) an inner layer material and components thereof, in terms of weight fractions, 60 parts of binary polypropylene, 37 parts of styrene-ethylene-butylene-styrene block copolymer, and 3 parts of chitosan, and a thickness of 30 microns; (5) the granules are uniformly mixed according to the foregoing formula, a three-layer co-extrusion film blowing machine is used, the die head temperature is ensured to be 180-210 DEG C, melt extrusion is performed, film blowing is performed by downward blowing, and then water ring cooling and winding into a cylinder film are sequentially performed, so that a composite film is obtained; further, in terms of weight fractions, 65 parts of amino acrylate is sprayed on the outer layer surface of the composite film by using a high-pressure airless spraying mode, then 32 parts of nano-zinc oxide dry powder is uniformly sieved on the surface of the amino acrylate coating by using an ultrasonic vibration sieve with a pore size of 25 nm at a frequency of 35 KHz, so that a prefabricated film is obtained; the prefabricated film is placed in an oxygen atmosphere, and irradiation treatment is performed, a radiation source is cobalt-60 gamma rays, an irradiation dose is 2 Gy, an irradiation dose rate is 10 Gy / min, after standing for 1 min, air blowing drying is performed, and thus a transfusion film is obtained.

[0050] Example 6

[0051] The embodiment provides a four-layer transfusion film, (1) the outer layer material and components thereof adopt, in terms of weight fraction, 32 parts of nano zinc oxide, 68 parts of amino acrylate, and the thickness is 5 microns; (2) the secondary outer layer material and components thereof adopt, in terms of weight fraction, 90 parts of homopolymer polypropylene, 10 parts of styrene-ethylene-butylene-styrene block copolymer, and the thickness is 25 microns; (3) the middle layer material and components thereof adopt, in terms of weight fraction, 30 parts of copolymer polypropylene, 60 parts of styrene-ethylene-butylene-styrene block copolymer, and 10 parts of cyclic olefin copolymer, and the thickness is 160 microns; (4) the inner layer material and components thereof adopt, in terms of weight fraction, 60 parts of binary polypropylene, 37 parts of styrene-ethylene-butylene-styrene block copolymer, and 3 parts of chitosan, and the thickness is 30 microns; (5) according to the foregoing formula, the granules are uniformly mixed, a three-layer co-extrusion film blowing machine is used, the die head temperature is ensured to be 180-210 DEG C, melt extrusion is carried out, film blowing is carried out by blowing downward, and then water ring cooling and winding into a cylinder film are sequentially carried out, so that the composite film is obtained; further, in terms of weight fraction, 65 parts of amino acrylate are sprayed on the outer layer surface of the composite film by using a high-pressure airless spraying mode, then 32 parts of nano zinc oxide dry powder are uniformly sieved on the surface of the amino acrylate coating by using an ultrasonic vibration sieve with a pore size of 25 nm under a frequency of 35 KHz, so that the prefabricated film is obtained; the prefabricated film is placed in an oxygen atmosphere, and irradiation treatment is carried out, a radiation source is a cobalt-60 gamma ray, an irradiation dose is 2 Gy, an irradiation dose rate is 10 Gy / min, after standing for 1 min, air blowing drying is carried out, and the transfusion film is obtained.

[0052] Comparative Example

[0053] Comparative Example 1

[0054] The difference between the present comparative example and the embodiment 1 is that the outer layer is not used, and the secondary outer layer is directly coated with a nano zinc oxide aqueous solution.

[0055] Comparative Example 2

[0056] The difference between the present comparative example and the embodiment 1 is that the nano zinc oxide aqueous solution is brushed on the surface of the amino acrylate.

[0057] Comparative Example 3

[0058] The difference between the present comparative example and the embodiment 1 is that the outer layer material and components thereof adopt, in terms of weight fraction, 10 parts of nano zinc oxide and 90 parts of amino acrylate.

[0059] Comparative Example 4

[0060] The difference between the present comparative example and the embodiment 1 is that the outer layer material and components thereof adopt, in terms of weight fraction, 60 parts of nano zinc oxide and 40 parts of amino acrylate.

[0061] Comparative Example 5

[0062] The difference between the present comparative example and Example 1 is that the middle layer raw material and components used in the present comparative example are as follows: copolymerized polypropylene 40 parts by weight, styrene-ethylene-butylene-styrene block copolymer 60 parts by weight, and the thickness is 145 μm.

[0063] Comparative Example 6

[0064] The difference between the present comparative example and Example 1 is that the inner layer raw material and components used in the present comparative example are as follows: binary polypropylene 60 parts by weight, styrene-ethylene-butylene-styrene block copolymer 40 parts by weight, and the thickness is 20 μm.

[0065] Test Example

[0066] The tensile strength, water vapor permeability, and antibacterial rate of the film material produced in Examples 1-6 and Comparative Examples 1-6 were detected, and the detection results are shown in Table 1:

[0067] Table 1

[0068]

[0069] According to Table 1, by comparing Examples 1-6 with Comparative Examples 1-6, it can be seen that by adding a suitable amount of aminopropyl acrylate in the outer layer formula, the stability of the outer layer nano zinc oxide and the uniformity of the coverage can be improved, and the antibacterial effect is greatly improved. In addition, compared with the existing technology of directly brushing the nano zinc oxide aqueous solution, the uniformity and compactness of the outer layer nano zinc oxide are better by using the ultrasonic vibration sieve screening method, and the use of cyclic olefin copolymer can effectively reduce the water vapor permeability of the middle layer, and chitosan can improve the antibacterial performance of the inner layer.

[0070] The above only describes preferred embodiments of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A four-layer film for infusion solutions, characterized in that, The four-layer infusion film comprises an outer layer, a sub-outer layer, a middle layer and an inner layer. The outer layer comprises the following raw material components and weight fractions: 25-35 parts of nano-zinc oxide, 50-80 parts of amino acrylate. The sub-outer layer comprises the following raw material components and weight fractions: 70-90 parts of homopolymer polypropylene, 10-30 parts of elastomer. The middle layer comprises the following raw material components and weight fractions: 20-40 parts of copolymer polypropylene, 40-60 parts of elastomer, 10-20 parts of cyclic olefin copolymer. The inner layer comprises the following raw material components and weight fractions: 60-80 parts of binary copolymer polypropylene, 20-40 parts of elastomer, 1-3 parts of chitosan. The four-layer infusion film comprises the following preparation steps: S1: using a three-layer co-extrusion under-blowing water-cooled blown film processing technology, the outer layer raw material, the middle layer raw material and the inner layer raw material are mixed uniformly according to the corresponding mass ratio, and then put into a co-extrusion blown film machine for co-extrusion blown film, and then sequentially cooled by a water ring and rolled into a cylindrical film to obtain a composite film; S2: using amino acrylate to spray the surface of the outer layer of the composite film, and then uniformly sieving nano-zinc oxide on the surface of the amino acrylate coating under ultrasonic vibration to obtain a preformed film; S3: placing the preformed film in an oxygen atmosphere for irradiation treatment, and then drying after standing for 1-5 minutes to obtain an infusion film.

2. The four-layer infusion film according to claim 1, characterized by The elastomer is at least one of styrene-ethylene-butylene-styrene block copolymer, styrene-ethylene-propylene-styrene copolymer and polyolefin elastomer.

3. The four-layer infusion film according to claim 1, characterized by The thickness of the outer layer is 1-10 μm.

4. The four-layer infusion film according to claim 1, characterized by The thickness of the sub-outer layer is 20-30 μm.

5. The four-layer infusion film according to claim 1, characterized by The thickness of the middle layer is 120-160 μm.

6. The four-layer infusion film according to claim 1, characterized by The thickness of the inner layer is 20-40 μm, and the total thickness of the infusion film is 190-220 μm.

7. The four-layer infusion film according to claim 1, characterized by In step S1, the extrusion temperature of the outer layer is 190-210℃, the extrusion temperature of the middle layer is 180-210℃, and the extrusion temperature of the inner layer is 190-200℃.

8. The four-layer infusion film according to claim 1, characterized by In step S2, the ultrasonic frequency range is 30-40 KHz, and the aperture of the vibrating sieve is 20-30 nm.

9. The four-layer infusion film according to claim 1, wherein In step S3, the radiation source is a cobalt-60 gamma ray, the irradiation dose is 2-10 Gy, and the irradiation dose rate is 10 Gy / min.

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