Falling-resistant recyclable MDOPE sterile packaging bag and preparation method thereof

Abstract

The invention belongs to the technical field of packaging materials, and particularly relates to a drop-resistant recyclable MDOPE sterile packaging bag and a preparation method thereof. The composite film is formed by sequentially compounding an MDOPE film, a VMBOPE film and a PE film. Wherein the MDOPE film is formed by co-extruding an inner layer, a middle layer and an outer layer which are sequentially connected, the PE film is formed by co-extruding a first layer, a second layer and a third layer, and the VMBOPE film is prepared from a BOPE film through a vacuum aluminum plating process. The prepared packaging bag has good falling resistance and antibacterial performance; and meanwhile, the single material of the membrane material is realized in the preparation process of the sterile packaging bag, so that waste materials are convenient to recycle and reuse, and environmental protection is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of packaging materials, and in particular to a drop-resistant and recyclable MDOPE aseptic packaging bag and a preparation method thereof. Background Art

[0002] Flexible packaging bags are made by sealing the films on each side of the bag to form a cavity to load the contents. Compared with rigid containers, they have the advantages of light weight, small volume for transportation, and convenient carrying. At present, they have been widely used in industries such as food, daily chemicals, medicines, and dangerous goods transportation. The main raw material for making flexible packaging bags is plastic film. Plastic film can be divided into single film and composite film. Single film is a film made by hot-melt extrusion of masterbatch particles by an extruder, and then through casting, calendering or hollow blow molding, and sometimes unidirectional or bidirectional stretching. The function of a single film is limited and single, and water and gas barrier properties are often not available at the same time. Therefore, most flexible packaging bags on the market are made of composite film. Composite film is a film produced by single film through coating, hot-melt extrusion, vacuum coating or adhesive lamination. It has good barrier properties and good mechanical properties and can withstand a certain degree of impact from the contents. Polyethylene is currently the most important general-purpose plastic and the polymer material with the largest output and the most widespread application among synthetic resins. Polyethylene can be processed using the same molding methods as general thermoplastics. It is odorless, non-toxic, feels like wax, has excellent low-temperature resistance, good chemical stability, can withstand corrosion from most acids and alkalis, is insoluble in general solvents at room temperature, has low water absorption, and is widely used in industries, agriculture, and daily necessities, among which packaging materials are the most widely used.

[0003] Chinese patent with publication number CN118386631A discloses a pure PE liquid self-supporting bag with high oxygen barrier, wherein the outer layer of the self-supporting bag is a uniaxially stretched PE film (MDOPE film), and the inner layer of the self-supporting bag is a 7-layer co-extruded high oxygen barrier PE film, and its specific structure is PE1 / PE2 / TIE3 / EVOH / TIE3 / PE2 / PE1; the physical blending of ethylene-vinyl alcohol copolymer resin and maleic anhydride grafted polyethylene promotes the compatibility of ethylene-vinyl alcohol copolymer and matrix PE resin, so that the distribution of ethylene-vinyl alcohol copolymer in the film layer is more uniform, thereby obtaining a PE film with high oxygen barrier performance; Chinese patent with publication number CN118772490A discloses an antibacterial packaging bag and a preparation method thereof, creatively setting the positional relationship between the antibacterial outer layer and the shielding inner layer and specific fillers, and a layered composite structure between the antibacterial outer layer and the shielding inner layer; the design of the structure and the selection of raw materials make the prepared packaging bag have good antibacterial function and anti-ultraviolet performance, and the preparation process is simple to operate and easy to industrialize. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a drop-resistant and recyclable MDOPE aseptic packaging bag and a preparation method thereof. The MDOPE film, VMBOPE film and PE film are compounded in sequence. The prepared packaging bag has good drop-resistant and antibacterial properties.

[0005] The technical solution provided by the present invention to solve the above technical problems is as follows: A drop-resistant and recyclable MDOPE aseptic packaging bag, wherein the aseptic packaging bag is formed by sequentially compounding an MDOPE film, a VMBOPE film and a PE film; The MDOPE film comprises an inner layer, a middle layer and an outer layer connected in sequence; the inner layer comprises 55-65 parts by weight of ultra-low molecular weight polyethylene, 35-45 parts by weight of ultra-high molecular weight polyethylene and 0.2-0.4 parts by weight of processing aid; the middle layer comprises 25-35 parts by weight of ultra-low molecular weight polyethylene, 45-55 parts by weight of ultra-high molecular weight polyethylene, 20-30 parts by weight of metallocene polyethylene and 0.3-0.5 parts by weight of processing aid; the outer layer comprises 30-40 parts by weight of ultra-high molecular weight polyethylene, 55-65 parts by weight of metallocene polyethylene and 0.3-0.5 parts by weight of processing aid; the MDOPE film is a uniaxially stretched PE film; the processing aid is 100991-K produced by Anpise Co., Ltd.

[0006] Plastic flexible packaging is the main form of packaging, mainly including polyethylene film, polypropylene film, polyester film, polycarbonate film, polyimide film, etc. Among them, polyethylene is currently the most important general-purpose plastic, and is also the polymer material with the largest output and the most widely used in synthetic resins. It is formed by addition polymerization of ethylene. Polyethylene also includes copolymers of ethylene and a small amount of α-olefins, which can be processed by general thermoplastic molding methods and has been widely used in packaging materials. However, the presence of factors such as transportation and falling from heights during circulation can easily cause the packaging bag to rupture, resulting in product loss. Therefore, in the present invention, MDOPE film, VMBOPE film and PE film are compounded in sequence to obtain a packaging bag with better performance. Among them, the MDOPE film is located in the outer layer of the packaging bag, and needs to have good toughness, strength and impact resistance, and can provide a certain strength of protection in the event of an accidental fall, to prevent rupture and protect the packaged goods. Therefore, in the present invention, the MDOPE film is co-extruded by the inner layer, middle layer and outer layer connected in sequence. The inner layer mainly includes ultra-low molecular weight polyethylene and ultra-high molecular weight polyethylene; the middle layer mainly includes ultra-low molecular weight polyethylene, ultra-high molecular weight polyethylene and metallocene polyethylene; the outer layer mainly includes ultra-high molecular weight polyethylene and metallocene polyethylene. Ultra-low molecular weight polyethylene is copolymerized by ethylene and polar monomers, and has high rigidity and toughness, good mechanical strength, good resistance to environmental stress cracking, and good softness; the main chain of ultra-high molecular weight polyethylene is long and entangled with each other, with a crystallinity of 65%-85%, and has outstanding wear resistance, excellent stress cracking resistance, high temperature creep resistance and low temperature resistance, and has excellent tensile strength and extremely high impact strength; metallocene polyethylene has the characteristics of wide molecular weight distribution and composition distribution, and has a lower heat sealing starting temperature than traditional polyethylene, good low temperature heat sealing performance, and high heat sealing strength. At the same time, in order to make the layers of the MDOPE film have better compatibility, the raw materials of the inner layer and the middle layer of the present invention contain the same raw material components of ultra-low molecular weight polyethylene and ultra-high molecular weight polyethylene, and the raw materials of the middle layer and the outer layer contain ultra-high molecular weight polyethylene and metallocene polyethylene; the layers in contact with each other have part of the same raw materials, so in the co-extrusion process, the repulsion between the layers caused by the large difference in raw materials can be reduced, so that the layers are more tightly compounded.

[0007] The VMBOPE film is made of BOPE film through vacuum aluminum plating process; BOPE film has high molecular weight orientation and crystal orientation, excellent impact resistance and puncture resistance, and small deformation after impact, which can significantly reduce the rate of broken packages during transportation and display. Furthermore, by vacuum aluminum plating on both sides of the BOPE film, a double-full aluminum-plated BOPE film is obtained, so that it has both the characteristics of a film and the characteristics of a metal. After aluminum plating, the film can effectively block light and ultraviolet rays, protect the contents from damage by light and ultraviolet rays, and extend the shelf life; and after aluminum plating, the aluminum plating layer has good conductivity, can eliminate the electrostatic effect, has good sealing performance, and ensures the sealing performance of the packaging.

[0008] The PE film is co-extruded by a first layer, a second layer and a third layer; the third layer and the inner layer are respectively connected to the two sides of the VMBOPE film; the surfaces of the third layer and the inner layer connected to the VMBOPE film are hydroxylated; and the surface of the first layer away from the second layer is grafted with chitosan.

[0009] Furthermore, the first layer comprises 55-65 parts by weight of linear low density polyethylene and 25-35 parts by weight of high density polyethylene; the second layer comprises 15-25 parts by weight of linear low density polyethylene, 55-65 parts by weight of high density polyethylene and 20-30 parts by weight of ultra low molecular weight polyethylene; the third layer comprises 25-35 parts by weight of high density polyethylene and 55-65 parts by weight of ultra low molecular weight polyethylene.

[0010] The inner layer of the packaging bag is made of PE film, which is composed of the first layer, the second layer and the third layer. The first layer mainly includes linear low-density polyethylene and high-density polyethylene, the second layer mainly includes linear low-density polyethylene, high-density polyethylene and ultra-low molecular weight polyethylene, and the third layer mainly includes high-density polyethylene and ultra-low molecular weight polyethylene. Among them, linear low-density polyethylene is copolymerized by ethylene and α-olefin. Due to the introduction of α-olefin, there are many short and regular branches on the molecular chain. The crystallinity is between high-density polyethylene and low-density polyethylene, which is suitable for film. Compared with low-density polyethylene, it has higher strength and toughness; high-density polyethylene has good heat and cold resistance, good chemical stability, high rigidity and toughness, but lacks flexibility; therefore, in the preparation process of PE film, the second layer containing a higher proportion of high-density polyethylene is used as the middle layer of the PE film. Since the first and third layers have linear low-density polyethylene and ultra-low molecular weight polyethylene with good flexibility, the film on both sides has high flexibility during the composite process, which can protect and buffer the second layer with strong rigidity, so that the prepared PE film has both flexibility and rigidity. Similarly, in the process of preparing PE film, the first layer and the second layer as well as the second layer and the third layer contain the same raw material components, that is, the layers in contact with each other have some of the same raw materials. During the composite process, the large repulsive force caused by the large difference in raw materials can be reduced, making the composite between the layers more tightly.

[0011] The present invention also provides a method for preparing a drop-resistant and recyclable MDOPE sterile packaging bag, comprising the following steps: S1. Preparation of MDOPE film: weigh and mix the raw materials according to the formula to prepare an inner layer mixture, a middle layer mixture and an outer layer mixture respectively, add the mixtures of each layer into the corresponding extruder hopper, heat at high temperature to plasticize into a melt, and extrude the MDOPE film from the extruder die by three-layer co-extrusion; wherein the extrusion speed of the extruder is 450±50Kg / h, and the heating temperature of the die is 195-205°C; S2. The surface of the inner layer connected to the VMBOPE film is hydroxylated: 1-hydroxycyclohexyl phenyl ketone is dissolved in ethanol, 1,2,3-butanetriol is added after ultrasonic dissolution, and the mixture is evenly coated on the surface of the inner layer connected to the VMBOPE film, covered with a glass plate, irradiated with ultraviolet light, and dried to obtain a hydroxylated inner layer; wherein the ultraviolet light irradiation conditions are: temperature 45-50°C, sample distance 15-18cm from the light source, illumination time 8-10min; the mass ratio of 1-hydroxycyclohexyl phenyl ketone, ethanol and 1,2,3-butanetriol is 0.1-0.25:10:2-4.5; In this step, free radicals are generated under heating conditions by using a free radical photoinitiator 1-hydroxycyclohexyl phenyl ketone. These free radicals can introduce oxygen-containing functional groups into the surface of the inner layer of the polymer, resulting in the generation of polar functional groups on the surface of the inner layer. 1,2,3-butanetriol is introduced to give the surface of the inner layer more polar functional groups, thereby increasing the polarity of the surface of the inner layer and increasing its bonding strength with the metal. S3, preparation of PE film: weigh and mix the raw materials according to the formula to prepare the first layer mixture, the second layer mixture and the third layer mixture respectively, add the mixture of each layer into the corresponding extruder hopper, heat at high temperature to plasticize into a melt, and extrude the PE film from the extruder die head by three-layer co-extrusion; wherein the extrusion speed of the extruder is 400±50Kg / h, and the heating temperature of the die head is 195-205°C; S4. The surface of the third layer connected to the VMBOPE film is hydroxylated: 1-hydroxycyclohexyl phenyl ketone is dissolved in ethanol, 1,2,3-butanetriol is added after ultrasonic dissolution, and the mixture is evenly coated on the surface of the third layer connected to the VMBOPE film, covered with a glass plate, irradiated with ultraviolet light, and dried to obtain a hydroxylated third layer; wherein the conditions for ultraviolet light irradiation are: temperature 45-50°C, sample distance 15-18cm from the light source, and illumination time 8-10min; the mass ratio of 1-hydroxycyclohexyl phenyl ketone, ethanol and 1,2,3-butanetriol is 0.1-0.25:10:2-4.5; The purpose of this step of hydroxylating the surface of the third layer connected to the VMBOPE film is similar to the purpose of step S2 of hydroxylating the surface of the inner layer connected to the VMBOPE film; S5. Perform chitosan grafting modification on the surface of the first layer away from the second layer: uniformly mix benzophenone and acrylic acid and drop them on the surface of the first layer away from the second layer, cover with a glass plate, irradiate with ultraviolet light, and then place in a vacuum drying oven at 45-55°C for 4-6 hours to obtain an acrylic acid grafted film; treat the acrylic acid grafted film with alkali solution and place in a vacuum drying oven at 50-65°C for 3-5 hours, then apply chitosan acetic acid solution on the surface, dry naturally in air, and obtain the first layer modified by chitosan grafting; wherein the conditions for ultraviolet light irradiation are: temperature 40-45°C, sample The light source is 13-15cm away from the sample, and the illumination time is 6-8min. The mass ratio of benzophenone to acrylic acid is 0.1:6-8.5. The process of alkali solution treatment is: coating the surface of the acrylic acid grafted film with sodium hydroxide solution, and washing with distilled water for 3-5 times after coating for 8-12min. The concentration of the sodium hydroxide solution is 0.2mol / L. The preparation method of chitosan acetic acid solution is: dissolving chitosan in acetic acid aqueous solution and stirring evenly. The volume ratio of acetic acid to water is 1:100, and the mass concentration of chitosan in acetic acid aqueous solution is 0.5%-1.2%. In this step, chitosan is a natural antibacterial agent that can destroy cell walls and membranes, change the permeability of cell membranes, cause leakage of cell contents, and achieve antibacterial and antimicrobial effects. In this step, acrylic acid is first grafted on the surface of the first layer to introduce polar groups on its surface to improve surface wettability, and then chitosan is coated; the acrylic acid graft chain contains a large number of polar groups such as carbonyl and hydroxyl groups, which can form hydrogen bonds with the hydroxyl groups of chitosan molecules, making the chitosan molecules more firmly bonded to the film surface; S6. Preparation of VMBOPE film: placing a BOPE film in an aluminum plating chamber for vacuum aluminum plating, and after the aluminum plating is completed, nitrogen is filled into the aluminum plating chamber in stages to obtain a single-sided aluminum-plated BOPE film; then placing the single-sided aluminum-plated BOPE film in an aluminum plating chamber for vacuum aluminum plating, and after the aluminum plating is completed, nitrogen is filled into the aluminum plating chamber in stages to obtain a double-sided aluminum-plated BOPE film; wherein, during the vacuum aluminum plating process of the aluminum-plated BOPE film, the unwinding speed of the BOPE film is 180-320 m / min, the wire feeding speed of the aluminum wire is 0.6-1.2 m / min, the temperature in the aluminum plating chamber is 1300±50°C, and the vacuum degree is greater than 2×10 -2 Pa; The BOPE film is subjected to corona treatment before vacuum aluminum plating; In this step, the corona treatment before vacuum aluminum plating can form a microstructure on the surface of the aluminum plating film, increase the surface energy, and thus improve the adhesion of the aluminum plating film; S7, subjecting the MDOPE film and the VMBOPE film to a composite process to obtain an MDOPE / VMBOPE composite film; S8, compounding the PE film with the MDOPE / VMBOPE composite film to obtain an MDOPE / VMBOPE / PE composite film; S9, ripening and bag-making the MDOPE / VMBOPE / PE composite film to obtain the aseptic packaging bag.

[0012] During the preparation of the composite film, the third layer and the inner layer are in contact with the VMBOPE film under pressure. Since the surfaces of the third layer and the inner layer in contact with the VMBOPE film are hydroxylated and contain more oxygen-containing functional groups such as hydroxyl groups, under the action of pressure, coordination bonds are formed between the third layer and the inner layer and the aluminum-plated layers on both sides of the VMBOPE film, so that a strong bond is formed between the VMBOPE film and the MDOPE film and the PE film, and the layers have a strong bonding effect.

[0013] The present invention has the following beneficial effects: The aseptic packaging bag prepared by the present invention is compounded in sequence by MDOPE film, VMBOPE film and PE film. The MDOPE film is formed by co-extrusion of an inner layer, a middle layer and an outer layer connected in sequence, the PE film is formed by co-extrusion of a first layer, a second layer and a third layer, and the VMBOPE film is prepared by a BOPE film through a vacuum aluminum plating process. In order to make each layer have better compatibility, the same raw material components are contained between adjacent layers, and the large repulsive force caused by excessive differences in raw materials can be reduced during the composite process, so that the layers are more closely compounded. In addition, the surfaces of the MDOPE film and the VMBOPE film in contact with the VMBOPE film are both hydroxylated and modified. During the composite process, the polar functional groups such as hydroxyl groups contained on the surfaces of the MDOPE film and the VMBOPE film form a strong bonding effect with the aluminum plating layer of the VMBOPE film, thereby enhancing the bonding effect between the layers; in addition, chitosan grafting modification is performed on the surface of the first layer away from the second layer, so that the prepared packaging bag has good antibacterial properties. At the same time, the aseptic packaging bag prepared by the present invention adopts homogeneous materials in the preparation process, realizes the single material of the film material, facilitates the recycling of waste materials, and is beneficial to environmental protection. DETAILED DESCRIPTION

[0014] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0015] The ultra-low molecular weight polyethylene (VL8005) used in the present invention was purchased from Dongguan Hongkuo Plastic Co., Ltd., the ultra-high molecular weight polyethylene (code: XW019002884028) was purchased from Sinopharm Chemical Reagent Co., Ltd., and metallocene polyethylene (industrial grade) was purchased from Mitsui Chemicals of Japan; linear low-density polyethylene (DFDA7042) was purchased from China National Petroleum Corporation; high-density polyethylene (BE0400) was purchased from Suzhou Fengjuan Plastic Raw Materials Co., Ltd.; 1-hydroxycyclohexyl phenyl ketone (98%), 1,2,3-butanetriol (TCI-B0918, 90.0% (GC)), dibenzophenone (AR), acrylic acid (AR (Shanghai test), ≥99.0%), and chitosan (SigmaAldrich-448869) were purchased from Sinopharm Chemical Reagent Co., Ltd., and all reagents are commonly available on the market.

[0016] Embodiment 1 A drop-resistant and recyclable MDOPE aseptic packaging bag is formed by compounding an MDOPE film, a VMBOPE film and a PE film in sequence.

[0017] The MDOPE film includes an inner layer, a middle layer and an outer layer connected in sequence; the inner layer includes 60 parts by weight of ultra-low molecular weight polyethylene, 40 parts by weight of ultra-high molecular weight polyethylene and 0.3 parts by weight of processing aid; the middle layer includes 30 parts by weight of ultra-low molecular weight polyethylene, 50 parts by weight of ultra-high molecular weight polyethylene, 25 parts by weight of metallocene polyethylene and 0.4 parts by weight of processing aid; the outer layer includes 35 parts by weight of ultra-high molecular weight polyethylene, 60 parts by weight of metallocene polyethylene and 0.4 parts by weight of processing aid; the MDOPE film is a uniaxially stretched PE film; the processing aid is 100991-K produced by Anpise Company.

[0018] The VMBOPE film is made from BOPE film by vacuum aluminum plating process; The PE film is co-extruded from the first layer, the second layer and the third layer; the third layer and the inner layer are connected to the two sides of the VMBOPE film respectively; the surfaces of the connection between the third layer and the inner layer and the VMBOPE film are hydroxylated; the surface of the first layer away from the second layer is grafted with chitosan.

[0019] The first layer includes 60 parts by weight of linear low-density polyethylene and 30 parts by weight of high-density polyethylene; the second layer includes 20 parts by weight of linear low-density polyethylene, 60 parts by weight of high-density polyethylene and 25 parts by weight of ultra-low molecular weight polyethylene; the third layer includes 30 parts by weight of high-density polyethylene and 60 parts by weight of ultra-low molecular weight polyethylene.

[0020] A method for preparing a drop-resistant and recyclable MDOPE sterile packaging bag comprises the following steps: S1. Preparation of MDOPE film: weigh and mix the raw materials according to the formula to prepare the inner layer mixture, the middle layer mixture and the outer layer mixture respectively, add the mixture of each layer into the corresponding extruder hopper, heat at high temperature to plasticize into a melt, and extrude the MDOPE film from the extruder die by three-layer co-extrusion; wherein the heating temperatures of 8 plasticizing sections are set to 55°C, 190°C, 200°C, 200°C, 200°C, 200°C, 200°C, 200°C, 200°C, 200°C, the extrusion speed of the extruder is 450±50Kg / h, the heating temperature of the die is 195-205°C, the molten film is inflated to form a film bubble, the blowing ratio is 2.8, and then cooled at room temperature, and then MDO longitudinal stretching is performed to obtain the film; the heating temperature of MDO longitudinal stretching is 90°C, and the stretching ratio is 2.6:1; the thickness of the obtained MDOPE film is 30μm; S2. The surface of the inner layer connected to the VMBOPE film is hydroxylated: 1-hydroxycyclohexyl phenyl ketone is dissolved in ethanol, 1,2,3-butanetriol is added after ultrasonic dissolution, and the mixture is evenly coated on the surface of the inner layer connected to the VMBOPE film, covered with a glass plate, irradiated with ultraviolet light, and then dried to obtain a hydroxylated inner layer; wherein, the conditions for ultraviolet light irradiation are: temperature 45°C, sample 16cm away from the light source, and illumination time 10min; the mass ratio of 1-hydroxycyclohexyl phenyl ketone, ethanol and 1,2,3-butanetriol is 0.15:10:3.2; the drying conditions are: drying at 45°C in a vacuum drying oven for 2.5h; the grafting rate is 5.2g / m 2 ; The calculation method of grafting rate is: grafting rate = (mass of grafted film (g) - mass of blank film (g)) / grafting area (m 2 ).

[0021] S3, preparation of PE film: weigh and mix the raw materials according to the formula to prepare the first layer mixture, the second layer mixture and the third layer mixture respectively, add the mixture of each layer into the corresponding extruder hopper, heat at high temperature to plasticize into a melt, and extrude the PE film from the extruder die head by three-layer co-extrusion; wherein the heating temperatures of 8 plasticizing sections are set to 50°C, 195°C, 200°C, 200°C, 200°C, 200°C, 200°C, 200°C, 200°C in sequence, the extrusion speed of the extruder is 400±50Kg / h, the heating temperature of the die head is 195-205°C, the molten film is inflated to form a film bubble, the blowing ratio is 2.2, and then cooled at room temperature; the thickness of the prepared PE film is 28μm; S4. The surface of the third layer connected to the VMBOPE film is hydroxylated: 1-hydroxycyclohexyl phenyl ketone is dissolved in ethanol, 1,2,3-butanetriol is added after ultrasonic dissolution, and the mixture is evenly coated on the surface of the third layer connected to the VMBOPE film, covered with a glass plate, irradiated with ultraviolet light, and then dried to obtain a hydroxylated third layer; wherein the ultraviolet light irradiation conditions are: temperature 45°C, sample 16cm away from the light source, illumination time 10min; the mass ratio of 1-hydroxycyclohexyl phenyl ketone, ethanol and 1,2,3-butanetriol is 0.15:10:3.2; the drying conditions are: drying at 45°C in a vacuum drying oven for 2.5h; the grafting rate is 4.8g / m 2 ; The calculation method of the grafting rate is the same as step S2; S5. Perform chitosan grafting modification on the surface of the first layer away from the second layer: mix benzophenone and acrylic acid evenly and drop them on the surface of the first layer away from the second layer, cover with a glass plate, irradiate with ultraviolet light, and then place in a vacuum drying oven at 50°C for 5 hours to obtain an acrylic acid grafted film; treat the acrylic acid grafted film with alkali solution and place in a vacuum drying oven at 55°C for 4 hours, then coat the surface with chitosan acetic acid solution, dry naturally in air, and obtain the first layer modified by chitosan grafting; wherein the conditions for ultraviolet light irradiation are: temperature 45°C, sample distance from light source 100mm 14cm, illumination time 8min; the mass ratio of benzophenone to acrylic acid is 0.1:7.2; the process of alkali solution treatment is: coating sodium hydroxide solution on the surface of acrylic acid grafted film, washing with distilled water 5 times after coating for 10min; the concentration of sodium hydroxide solution is 0.2mol / L; the preparation method of chitosan acetic acid solution is: dissolving chitosan in acetic acid aqueous solution and stirring evenly; the volume ratio of acetic acid to water is 1:100, and the mass concentration of chitosan in acetic acid aqueous solution is 1.0%; the grafting rate is: 7.5g / m 2 ; The calculation method of the grafting rate is the same as step S2; S6. Preparation of VMBOPE film: placing a BOPE film in an aluminum plating chamber for vacuum aluminum plating, and filling the aluminum plating chamber with nitrogen in stages after the aluminum plating is completed to obtain a single-sided aluminum-plated BOPE film; then placing the single-sided aluminum-plated BOPE film in an aluminum plating chamber for vacuum aluminum plating, and filling the aluminum plating chamber with nitrogen in stages after the aluminum plating is completed to obtain a double-sided aluminum-plated BOPE film; wherein, during the vacuum aluminum plating process of the aluminum-plated BOPE film, the unwinding speed of the BOPE film is 220 m / min, the wire feeding speed of the aluminum wire is 0.8 m / min, the temperature in the aluminum plating chamber is 1300±50°C, and the vacuum degree is greater than 2×10 -2 Pa; BOPE film is corona treated before vacuum aluminum plating; discharge voltage is controlled at 10000V / m 2 ; The thickness of the aluminum coating is 25nm; The thickness of the VMBOPE film is 20μm; S7, dry-compounding the MDOPE film and the VMBOPE film, with the oven temperature at 50° C. and the composite tension at 6.5 kg, to obtain a MDOPE / VMBOPE dry composite film; S8, dry-compounding the PE film and the MDOPE / VMBOPE dry composite film, with the oven temperature being 55° C. and the composite tension being 6.8 kg, to obtain the MDOPE / VMBOPE / PE dry composite film; S9. Place the MDOPE / VMBOPE / PE dry composite film in a 45°C oven for aging for 48 hours and then make a sterile packaging bag; the heat sealing temperature is 130°C, the temperature fluctuation is controlled at ±1°C, each position of the bag is heat-sealed 4 times, and the bag making speed is controlled at 65 knives / min.

[0022] Embodiment 2 Compared with the first embodiment, this embodiment has the following differences, specifically: In the MDOPE film, the inner layer includes 55 parts by weight of ultra-low molecular weight polyethylene, 35 parts by weight of ultra-high molecular weight polyethylene and 0.2 parts by weight of processing aid; the middle layer includes 25 parts by weight of ultra-low molecular weight polyethylene, 45 parts by weight of ultra-high molecular weight polyethylene, 20 parts by weight of metallocene polyethylene and 0.3 parts by weight of processing aid; the outer layer includes 30 parts by weight of ultra-high molecular weight polyethylene, 55 parts by weight of metallocene polyethylene and 0.3 parts by weight of processing aid; In the PE film, the first layer includes 55 parts by weight of linear low-density polyethylene and 25 parts by weight of high-density polyethylene; the second layer includes 15 parts by weight of linear low-density polyethylene, 55 parts by weight of high-density polyethylene and 20 parts by weight of ultra-low molecular weight polyethylene; the third layer includes 25 parts by weight of high-density polyethylene and 55 parts by weight of ultra-low molecular weight polyethylene.

[0023] In the preparation process of the aseptic packaging bag, in step S1, the blowing ratio is 2.6, the stretching ratio is 2.2:1, and the thickness of the obtained MDOPE film is 26 μm; in step S2, the conditions of ultraviolet light irradiation are: temperature 45°C, the sample is 15 cm away from the light source, and the illumination time is 8 minutes; the mass ratio of 1-hydroxycyclohexyl phenyl ketone, ethanol and 1,2,3-butanetriol is 0.1:10:2; the drying conditions are: drying at 40°C in a vacuum drying oven for 2 hours; the grafting rate is: 5.0 g / m 2 ; In step S3, the blowing ratio is 2.0, and the thickness of the PE film is 25 μm; in step S4, the conditions for ultraviolet light irradiation are: temperature 45°C, sample distance 15 cm from the light source, and illumination time 8 min; the mass ratio of 1-hydroxycyclohexyl phenyl ketone, ethanol and 1,2,3-butanetriol is 0.1:10:2; the drying conditions are: drying at 40°C in a vacuum drying oven for 2 h, and the grafting rate is 4.6 g / m 2 ; In step S5, after ultraviolet light irradiation, the film is placed in a vacuum drying oven at 45°C for 4 hours to obtain an acrylic acid grafted film; the acrylic acid grafted film is treated with alkali solution and placed in a vacuum drying oven at 50°C for 3 hours. The conditions for ultraviolet light irradiation are: temperature 40°C, sample 13cm away from the light source, and illumination time 6min; the mass ratio of benzophenone to acrylic acid is 0.1:6; the process of alkali solution treatment is: coating sodium hydroxide solution on the surface of the acrylic acid grafted film, and washing it with distilled water 3 times after coating for 8 minutes; the mass concentration of chitosan in acetic acid aqueous solution is 0.5%; the grafting rate is: 7.2g / m 2 In step S6, the unwinding speed of the BOPE film is 180m / min, the wire feeding speed of the aluminum wire is 0.6m / min, the thickness of the aluminum coating is 20nm, and the discharge voltage is controlled at 9000V / m 2; In step S7, the oven temperature is 45°C and the composite tension is 6kg; in step S8, the oven temperature is 50°C and the composite tension is 6.2kg; in step S9, the heat sealing temperature is 120°C, each position of the bag is heat sealed 3 times, and the bag making speed is controlled at 60 knives / min.

[0024] Embodiment 3 Compared with the first embodiment, this embodiment has the following differences, specifically: In the MDOPE film, the inner layer includes 65 parts by weight of ultra-low molecular weight polyethylene, 45 parts by weight of ultra-high molecular weight polyethylene and 0.4 parts by weight of processing aid; the middle layer includes 35 parts by weight of ultra-low molecular weight polyethylene, 55 parts by weight of ultra-high molecular weight polyethylene, 30 parts by weight of metallocene polyethylene and 0.5 parts by weight of processing aid; the outer layer includes 40 parts by weight of ultra-high molecular weight polyethylene, 65 parts by weight of metallocene polyethylene and 0.5 parts by weight of processing aid; In the PE film, the first layer includes 65 parts by weight of linear low-density polyethylene and 35 parts by weight of high-density polyethylene; the second layer includes 25 parts by weight of linear low-density polyethylene, 65 parts by weight of high-density polyethylene and 30 parts by weight of ultra-low molecular weight polyethylene; the third layer includes 35 parts by weight of high-density polyethylene and 65 parts by weight of ultra-low molecular weight polyethylene.

[0025] In the preparation process of the aseptic packaging bag, in step S1, the blowing ratio is 2.9, the stretching ratio is 2.8:1, and the thickness of the obtained MDOPE film is 34 μm; in step S2, the conditions of ultraviolet light irradiation are: temperature 50°C, sample distance 18 cm from the light source, and illumination time 10 min; the mass ratio of 1-hydroxycyclohexyl phenyl ketone, ethanol and 1,2,3-butanetriol is 0.25:10:4.5; the drying conditions are: drying at 50°C in a vacuum drying oven for 3 hours; the grafting rate is: 4.8 g / m 2 ; In step S3, the blowing ratio is 2.4, and the thickness of the PE film is 32 μm; in step S4, the conditions for ultraviolet light irradiation are: temperature 50°C, sample distance 18 cm from the light source, and illumination time 10 min; the mass ratio of 1-hydroxycyclohexyl phenyl ketone, ethanol and 1,2,3-butanetriol is 0.25:10:4.5; the drying conditions are: drying at 50°C in a vacuum drying oven for 3 h, and the grafting rate is 4.3 g / m 2; In step S5, after ultraviolet light irradiation, the film is placed in a vacuum drying oven at 55°C for 6 hours to obtain an acrylic acid grafted film; the acrylic acid grafted film is treated with alkali solution and placed in a vacuum drying oven at 65°C for 5 hours. The conditions for ultraviolet light irradiation are: temperature 45°C, sample 15cm away from the light source, and illumination time 8min; the mass ratio of benzophenone to acrylic acid is 0.1:8.5; the process of alkali solution treatment is: coating sodium hydroxide solution on the surface of the acrylic acid grafted film, and washing it with distilled water 5 times after coating for 12 minutes; the mass concentration of chitosan in acetic acid aqueous solution is 1.2%; the grafting rate is: 7.0g / m 2 In step S6, the unwinding speed of the BOPE film is 280m / min, the wire feeding speed of the aluminum wire is 1.2m / min, the thickness of the aluminum coating is 28nm, and the discharge voltage is controlled at 9000V / m 2 ; In step S7, the oven temperature is 52°C and the composite tension is 6.8kg; in step S8, the oven temperature is 58°C and the composite tension is 7.2kg; in step S9, the heat sealing temperature is 135°C, each position of the bag is heat sealed 5 times, and the bag making speed is controlled at 70 knives / min.

[0026] Comparative Example 1 Compared with Example 1, the surface of the inner layer connected to the VMBOPE film and the surface of the third layer connected to the VMBOPE film are not hydroxylated, and the surface of the first layer away from the second layer is not grafted with chitosan. The rest is referenced to Example 1. The specific preparation process is as follows: S1. Preparation of MDOPE film: weighing and mixing raw materials according to the formula to prepare an inner layer mixture, a middle layer mixture and an outer layer mixture respectively, adding each layer mixture into a corresponding extruder hopper, heating at high temperature to plasticize into a melt, and extruding from the extruder die head by three-layer co-extrusion to obtain an MDOPE film; S2, preparation of PE film: weighing and mixing raw materials according to the formula to prepare the first layer mixture, the second layer mixture and the third layer mixture respectively, adding each layer mixture into the corresponding extruder hopper, heating at high temperature to plasticize into a melt, and extruding from the extruder die head by three-layer co-extrusion to obtain a PE film; S3, preparation of VMBOPE film: placing the BOPE film in an aluminum plating chamber for vacuum aluminum plating, and after the aluminum plating is completed, nitrogen is filled into the aluminum plating chamber in stages to obtain a single-sided aluminum-plated BOPE film; then placing the single-sided aluminum-plated BOPE film in an aluminum plating chamber for vacuum aluminum plating, and after the aluminum plating is completed, nitrogen is filled into the aluminum plating chamber in stages to obtain a double-sided aluminum-plated BOPE film; S4, subjecting the MDOPE film and the VMBOPE film to a composite process to obtain an MDOPE / VMBOPE composite film; S5, compounding the PE film with the MDOPE / VMBOPE composite film to obtain an MDOPE / VMBOPE / PE composite film; S6. The MDOPE / VMBOPE / PE composite film is cured and bag-formed to obtain a sterile packaging bag.

[0027] Comparative Example 2 Compared with Example 1, this comparative example composites the MDOPE film and the VMBOPE film to obtain a sterile packaging bag, and the rest is referred to Example 1. The specific preparation process is as follows: S1. Preparation of MDOPE film: weighing and mixing raw materials according to the formula to prepare an inner layer mixture, a middle layer mixture and an outer layer mixture respectively, adding each layer mixture into a corresponding extruder hopper, heating at high temperature to plasticize into a melt, and extruding from the extruder die head by three-layer co-extrusion to obtain an MDOPE film; S2. The surface of the inner layer connected to the VMBOPE film is hydroxylated: 1-hydroxycyclohexyl phenyl ketone is dissolved in ethanol, 1,2,3-butanetriol is added after ultrasonic dissolution, and the mixture is evenly coated on the surface of the inner layer connected to the VMBOPE film, covered with a glass plate, irradiated with ultraviolet light, and dried to obtain a hydroxylated inner layer; S3, preparation of VMBOPE film: placing the BOPE film in an aluminum plating chamber for vacuum aluminum plating, and after the aluminum plating is completed, nitrogen is filled into the aluminum plating chamber in stages to obtain a single-sided aluminum-plated BOPE film; then placing the single-sided aluminum-plated BOPE film in an aluminum plating chamber for vacuum aluminum plating, and after the aluminum plating is completed, nitrogen is filled into the aluminum plating chamber in stages to obtain a double-sided aluminum-plated BOPE film; S4, subjecting the MDOPE film and the VMBOPE film to a composite process to obtain an MDOPE / VMBOPE composite film; S5. Ripening and bag-making the MDOPE / VMBOPE composite film to obtain a packaging bag.

[0028] Comparative Example 3 Compared with Example 1, this comparative example composites the PE film with the VMBOPE film to obtain a sterile packaging bag, and the rest is referred to Example 1. The specific preparation process is as follows: S1. Preparation of PE film: weighing and mixing raw materials according to the formula to prepare the first layer mixture, the second layer mixture and the third layer mixture respectively, adding each layer mixture into the corresponding extruder hopper, heating at high temperature to plasticize into a melt, and extruding from the extruder die head by three-layer co-extrusion to obtain a PE film; S2. The surface of the third layer connected to the VMBOPE film is hydroxylated: 1-hydroxycyclohexyl phenyl ketone is dissolved in ethanol, 1,2,3-butanetriol is added after ultrasonic dissolution, and the mixture is evenly coated on the surface of the third layer connected to the VMBOPE film, covered with a glass plate, irradiated with ultraviolet light, and dried to obtain a hydroxylated third layer; S3, performing chitosan grafting modification on the surface of the first layer away from the second layer: uniformly mixing benzophenone and acrylic acid, dripping the mixture on the surface of the first layer away from the second layer, covering with a glass plate, irradiating with ultraviolet light, and drying to obtain an acrylic acid grafted film; treating the acrylic acid grafted film with alkaline solution and drying, coating the surface with chitosan acetic acid solution, and naturally air-drying to obtain a first layer grafted with chitosan; S4, preparation of VMBOPE film: placing the BOPE film in an aluminum plating chamber for vacuum aluminum plating, and after the aluminum plating is completed, nitrogen is filled into the aluminum plating chamber in stages to obtain a single-sided aluminum-plated BOPE film; then placing the single-sided aluminum-plated BOPE film in an aluminum plating chamber for vacuum aluminum plating, and after the aluminum plating is completed, nitrogen is filled into the aluminum plating chamber in stages to obtain a double-sided aluminum-plated BOPE film; S5, compounding the PE film and the VMBOPE film to obtain a PE / VMBOPE composite film; S6. The PE / VMBOPE composite film is cured and bag-formed to obtain a sterile packaging bag.

[0029] Related tests: The packaging bags prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to relevant tests. The tensile strength in the MD and TD directions was tested using a universal tensile testing machine. The pressure test was performed as follows: the packaging bag was sealed after being filled with 500g of water, and then flat-pressed with an 80kg weight, and maintained in the pressed state for 60s without damage or cracking. The drop test was performed as follows: the packaging bag was filled with 500g of water and dropped from a height of 1m for 6 times without damage or cracking. The test results are shown in Table 1.

[0030] Table 1 Related performance test results It can be seen from the above test results that Examples 1 to 3 have good mechanical properties compared with Comparative Examples 1 to 3, and have good pressure resistance and drop resistance, especially Example 1 has the best performance.

[0031] Antimicrobial test: The packaging bags obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were tested for antibacterial properties in accordance with GB / T 31402-2015 “Test methods for antibacterial properties of plastics and plastic surfaces”. The test results are shown in Table 2.

[0032] Table 2 Antibacterial test results It can be seen from the above test results that Examples 1 to 3 and Comparative Example 3 all have good antibacterial effects, while the packaging bags prepared in Comparative Examples 1 and 2 do not have antibacterial effects because there is no grafted chitosan.

[0033] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0034] Although the embodiments of the present application 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 application, and that the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A drop-resistant and recyclable MDOPE sterile packaging bag, characterized in that: The aseptic packaging bag is formed by compounding an MDOPE film, a VMBOPE film and a PE film in sequence; The MDOPE film comprises an inner layer, a middle layer and an outer layer connected in sequence; the inner layer comprises 55-65 parts by weight of ultra-low molecular weight polyethylene, 35-45 parts by weight of ultra-high molecular weight polyethylene and 0.2-0.4 parts by weight of a processing aid; the middle layer comprises 25-35 parts by weight of ultra-low molecular weight polyethylene, 45-55 parts by weight of ultra-high molecular weight polyethylene, 20-30 parts by weight of metallocene polyethylene and 0.3-0.5 parts by weight of a processing aid; the outer layer comprises 30-40 parts by weight of ultra-high molecular weight polyethylene, 55-65 parts by weight of metallocene polyethylene and 0.3-0.5 parts by weight of a processing aid; The VMBOPE film is made of BOPE film through a vacuum aluminum plating process; the PE film is co-extruded by a first layer, a second layer and a third layer; the third layer and the inner layer are respectively connected to the two sides of the VMBOPE film; the surfaces of the third layer and the inner layer at the connection with the VMBOPE film are hydroxylated; the surface of the first layer away from the second layer is grafted with chitosan.

2. The drop-resistant and recyclable MDOPE aseptic packaging bag according to claim 1, characterized in that: The first layer comprises 55-65 parts by weight of linear low density polyethylene and 25-35 parts by weight of high density polyethylene; the second layer comprises 15-25 parts by weight of linear low density polyethylene, 55-65 parts by weight of high density polyethylene and 20-30 parts by weight of ultra low molecular weight polyethylene; the third layer comprises 25-35 parts by weight of high density polyethylene and 55-65 parts by weight of ultra low molecular weight polyethylene.

3. The method for preparing the drop-resistant and recyclable MDOPE aseptic packaging bag according to any one of claims 1 to 2, characterized in that: The steps include: S1. Preparation of MDOPE film: weighing and mixing raw materials according to the formula to prepare an inner layer mixture, a middle layer mixture and an outer layer mixture respectively, adding each layer mixture into a corresponding extruder hopper, heating at high temperature to plasticize into a melt, and extruding from the extruder die head by three-layer co-extrusion to obtain an MDOPE film; S2. The surface of the inner layer connected to the VMBOPE film is hydroxylated: 1-hydroxycyclohexyl phenyl ketone is dissolved in ethanol, 1,2,3-butanetriol is added after ultrasonic dissolution, and the mixture is evenly coated on the surface of the inner layer connected to the VMBOPE film, covered with a glass plate, irradiated with ultraviolet light, and dried to obtain a hydroxylated inner layer; S3, preparation of PE film: weighing and mixing raw materials according to the formula to prepare the first layer mixture, the second layer mixture and the third layer mixture respectively, adding each layer mixture into the corresponding extruder hopper, heating at high temperature to plasticize into a melt, and extruding from the extruder die head by three-layer co-extrusion to obtain a PE film; S4. The surface of the third layer connected to the VMBOPE film is hydroxylated: 1-hydroxycyclohexyl phenyl ketone is dissolved in ethanol, 1,2,3-butanetriol is added after ultrasonic dissolution, and the mixture is evenly coated on the surface of the third layer connected to the VMBOPE film, covered with a glass plate, irradiated with ultraviolet light, and dried to obtain a hydroxylated third layer; S5, performing chitosan grafting modification on the surface of the first layer away from the second layer: uniformly mixing benzophenone and acrylic acid, dripping the mixture on the surface of the first layer away from the second layer, covering it with a glass plate, irradiating it with an ultraviolet lamp, and drying it to obtain an acrylic acid grafted film; treating the acrylic acid grafted film with an alkali solution and drying it, coating the surface with a chitosan acetic acid solution, and air-drying it naturally to obtain a first layer grafted with chitosan; S6, preparation of VMBOPE film: placing the BOPE film in an aluminum plating chamber for vacuum aluminum plating, and after the aluminum plating is completed, nitrogen is filled into the aluminum plating chamber in stages to obtain a single-sided aluminum-plated BOPE film; then placing the single-sided aluminum-plated BOPE film in an aluminum plating chamber for vacuum aluminum plating, and after the aluminum plating is completed, nitrogen is filled into the aluminum plating chamber in stages to obtain a double-sided aluminum-plated BOPE film; S7, subjecting the MDOPE film and the VMBOPE film to a composite process to obtain an MDOPE / VMBOPE composite film; S8, compounding the PE film with the MDOPE / VMBOPE composite film to obtain an MDOPE / VMBOPE / PE composite film; S9, ripening and bag-making the MDOPE / VMBOPE / PE composite film to obtain the aseptic packaging bag.

4. The method for preparing the drop-resistant and recyclable MDOPE aseptic packaging bag according to claim 3, characterized in that: In step S2 and step S4, the conditions for ultraviolet lamp irradiation are: temperature 45-50°C, sample 15-18cm away from the light source, and illumination time 8-10min; in step S5, the conditions for ultraviolet lamp irradiation are: temperature 40-45°C, sample 13-15cm away from the light source, and illumination time 6-8min.

5. The method for preparing the drop-resistant and recyclable MDOPE aseptic packaging bag according to claim 3, characterized in that: In step S5, the process of alkali solution treatment is: coating the surface of the acrylic acid grafted membrane with sodium hydroxide solution, coating for 8-12 minutes, and then washing with distilled water for 3-5 times.

6. The method for preparing the drop-resistant and recyclable MDOPE aseptic packaging bag according to claim 3, characterized in that: In step S5, the chitosan acetic acid solution is prepared by dissolving chitosan in an acetic acid aqueous solution and stirring the solution evenly.

7. The method for preparing the drop-resistant and recyclable MDOPE aseptic packaging bag according to claim 3, characterized in that: In step S1, the extrusion speed of the extruder is 450±50Kg / h, and the heating temperature of the die head is 195-205°C; in step S3, the extrusion speed of the extruder is 400±50Kg / h, and the heating temperature of the die head is 195-205°C.

8. The method for preparing the drop-resistant and recyclable MDOPE aseptic packaging bag according to claim 3, characterized in that: In step S6, during the vacuum aluminum plating process of the aluminum-plated BOPE film, the unwinding speed of the BOPE film is 180-320 m / min, the wire feeding speed of the aluminum wire is 0.6-1.2 m / min, the temperature in the aluminum plating chamber is 1300±50°C, and the vacuum degree is greater than 2×10 -2 Pa.

9. The method for preparing the drop-resistant and recyclable MDOPE aseptic packaging bag according to claim 3, characterized in that: In step S6, the BOPE film is subjected to corona treatment before vacuum aluminum plating.

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