Fresh food bacteriostatic packaging material and preparation method thereof

Abstract

The invention relates to the technical field of food packaging materials, in particular to a fresh food bacteriostatic packaging material and a preparation method thereof.The packaging material structurally comprises a first PET film layer, a second ink film layer, a third VMPET film layer or AL barrier layer and a fourth PE bacteriostatic film layer from top to bottom, according to the fresh food antibacterial packaging material formed by processing the packaging structure, through the arrangement, the first PET film layer, the second ink film layer and the third VMPET film layer or the AL barrier layer are arranged in the packaging material film, the packaging material film has good mechanical properties of strength, toughness and barrier property, the integrity of a product in the transportation and storage process can be protected, and the packaging structure can be used for packaging fresh food. The polyethylene PE antibacterial film layer is arranged in the packaging material film, so that antibacterial components in the polyethylene PE antibacterial film layer are released lastingly and slowly, the antibacterial components continuously play an antibacterial role in the shelf life of a product, and adverse effects on a human body or the environment due to excessive release are avoided.

Description

Technical Field

[0001] The invention relates to the technical field of production and processing of packaging composite films, in particular to an antibacterial packaging material for fresh food and a preparation method thereof. Background Art

[0002] In today's era of health and safety, the research and development of antibacterial packaging materials for fresh food has become a key area in the packaging industry. As consumers' requirements for product preservation and hygiene continue to increase, traditional packaging materials can no longer meet the demand. The research and development of antibacterial packaging materials is committed to effectively integrating antibacterial agents into the packaging matrix, among which nanotechnology plays an important role. For example, nanosilver particles and nanozinc ions can inhibit the growth and reproduction of microorganisms such as bacteria and molds.

[0003] When some antibacterial packaging materials for fresh food carry out antibacterial modification on the packaging film, less attention is paid to the overall strength, toughness and barrier properties of the packaging film, and it is difficult to ensure the integrity of the packaging film during transportation and product protection and storage. Therefore, in order to solve the above problems, an antibacterial packaging material for fresh food and a preparation method thereof are proposed. Summary of the invention

[0004] The purpose of the present invention is to provide an antibacterial packaging material for fresh food and a preparation method thereof, which is used to solve the problem that when some antibacterial packaging materials for fresh food are subjected to antibacterial modification treatment on the packaging film, less attention is paid to the overall strength, toughness and barrier properties of the packaging film, and it is difficult to ensure the integrity of the packaging film during transportation and storage of the product.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] Disclosed is an antibacterial packaging material for fresh food and a preparation method thereof. The distribution structure of the packaging material from top to bottom is: a first PET film layer, a second ink film layer, a third VMPET film layer or an AL barrier layer, and a fourth polyethylene PE antibacterial film layer. The polyethylene PE antibacterial film layer is mainly prepared by a film blowing process and is made into the packaging material by three-layer co-extrusion. The outer layer is mixed with low-density polyethylene in a ratio of 10-25% and linear low-density polyethylene in a ratio of 75-90%. The middle layer is mixed with low-density polyethylene in a ratio of 10-20%, linear low-density polyethylene in a ratio of 70-85%, and an antibacterial agent in a ratio of 2-5%. The inner layer is mixed with polyethylene in a ratio of 10-15%, linear low-density polyethylene in a ratio of 40-50%, metallocene polyethylene in a ratio of 30-40%, and an antibacterial agent in a ratio of 2-5%. The antibacterial agent is nano-active zinc oxide.

[0007] Preferably, when the third layer is a VMPET film layer, specifically, a method for preparing an antibacterial packaging material for fresh food is:

[0008] A1. Preparation of the first PET film layer:

[0009] First, the PET resin slices are pre-dried to prevent hydrolysis, and then extruded into amorphous thick slices through a T-die at 280°C in an extruder, quenched by a cooling drum or a coolant, and then subjected to a biaxial stretching treatment, wherein the longitudinal stretching is to preheat the thick slice to 86-87°C and stretch it 3 times along the plane extension direction of the thick slice at this temperature, the transverse stretching preheating temperature is 98-100°C, the stretching temperature is 100-120°C, and the stretching ratio is 2.5-4.0. The film after longitudinal and transverse stretching is heat-set, wherein the heat-setting temperature is 230-240°C, and a biaxially stretched PET film layer with good thermal stability is prepared;

[0010] A2. Preparation of the third VMPET film layer:

[0011] (1) Preparation of aluminum nitride coating: half of the biaxially oriented PET film obtained in step A1 above is used as the raw material for secondary processing and is sent into a coating chamber containing metallic chromium, and the vacuum degree is maintained at less than 1.5×10 -3 Pa, and heated to 135 degrees Celsius, nitrogen and argon were continuously introduced into the device, the sputtering power was set to 12KW, and magnetron sputtering was continued for 5 minutes. Nitrogen reacted with the sputtered chromium atoms to form a nitride layer, which was evenly deposited on the surface of the biaxially oriented PET film layer;

[0012] (2) Aluminum evaporation: The biaxially oriented PET film layer is rolled into a tube, and before evaporation, the tube-shaped PET film layer is transported and moved by an external unwinding device and a winding device, and the PET film layer is transported and moved inside a vacuum evaporation machine, and a vacuum pump provided inside the vacuum evaporation machine is used for vacuuming, so that the vacuum degree reaches 1.3×10 -2 ~1.3×10 -3 Pa, the evaporation boat is heated to 1300℃~1400℃, and then the aluminum wire with a purity of 99.9% is continuously fed to the evaporation boat, the unwinding speed of the PET film layer, the winding speed of the PET film layer, the aluminum wire feeding speed and the evaporation amount of the aluminum wire are adjusted, and the cooling source is turned on to make the aluminum wire melt and evaporate continuously on the evaporation boat, so that a bright aluminum layer is formed on the surface of the nitride layer of the PET film layer after cooling, the thickness of the aluminum coating layer is 50~150nm, and the width of the aluminum coating film is 800mm~2000mm, so as to form a VMPET film layer, and then the aluminum coating layer is subjected to laser thickness measurement processing, and after the aluminum coating layer thickness inspection is qualified, it is flattened and rolled up;

[0013] A3. Preparation of polyethylene PE antibacterial film layer:

[0014] The polyethylene PE antibacterial film layer is processed by a three-layer co-extrusion film blowing machine. The outer layer raw material is a mixture of 10-25% low-density polyethylene and 75-90% linear low-density polyethylene. The middle layer raw material is a mixture of 10-20% low-density polyethylene, 70-85% linear low-density polyethylene, and 2-5% nano-active zinc oxide. The inner layer raw material is a mixture of 10-15% polyethylene, 40-50% linear low-density polyethylene, 30-40% metallocene polyethylene, and 2-5% nano-active zinc oxide.

[0015] The working process of the three-layer co-extrusion film blowing machine when producing the polyethylene PE antibacterial film layer is as follows: first, three layers of different kinds of raw materials are placed in their respective extruders, heated and melted by their respective extruders, and then formed into a melt through the die head. The melt then enters the blowing device. During this process, air is injected into the melt and quickly blown to form a film. The film then enters the cooling system to quickly cool and harden. Finally, the traction and winding device tractions and winds up the hardened film;

[0016] A4. Composite process treatment:

[0017] (1) The bottom surface of the first PET film layer and the top surface of the third VMPET film layer are subjected to corona treatment, and the second ink film layer uses a UV ink whose base resin is polyurethane acrylate, and the UV ink is coated and distributed on the surface of the embossing roller of the printing equipment;

[0018] (2) A base film roll with the first layer of PET film installed on the motor reel is placed in the direction specified by the equipment, and the base film roll of the third layer of VMPET film is installed. UV ink is applied to the bottom of the first layer of PET film through the inside of the printing equipment. The coating amount of UV ink is 2.5-3.5g / ㎡. The top of the third layer of VMPET film is compounded with UV ink and then sent to the UV curing machine. The wavelength of the ultraviolet lamp is set to 300-400nm and the radiation energy is set to 50-100J / cm 2 , solidified into a second ink film layer connecting the first PET film layer and the third VMPET film layer;

[0019] (3) A base film roll with a fourth polyethylene PE antibacterial film layer installed is arranged on the motor reel, and the film is placed according to the direction specified by the equipment, and the base film roll composed of the first PET film layer, the second ink film layer, and the third VMPET film layer is installed, and then a set of rollers of the rubber roller is lifted so that the base film roll does not contact the rubber roller, polyurethane adhesive is added to the adhesive disk, and the drying oven heater is turned on. The pressure between the rubber roller and the anilox roller is adjusted so that a thin and uniform layer of polyurethane adhesive is coated on the rubber roller. The drying oven heater is a three-stage heating structure, wherein the front end temperature of the drying oven is 50-60°C, the middle end temperature is 60-70°C, and the rear end temperature is 70-80°C. The coating amount of the polyurethane adhesive is 2.5-3.5g / ㎡. When the drying oven temperature reaches the requirement, the cooling equipment and the heat dissipation equipment are used to maintain the drying oven temperature, and the rollers on the rubber roller are lowered to compound the fourth polyethylene PE antibacterial film layer with the third VMPET film layer through the polyurethane adhesive;

[0020] A5. Ripening treatment:

[0021] The film compounded in the above step A4 is placed in a curing room, the temperature inside the curing room is maintained at 45-50°C, a ventilation and exhaust pipe structure is set inside the curing room, and the curing time is 24-36 hours, so that the main agent and curing agent inside the polyurethane adhesive undergo cross-linking reaction, and interact with the fourth layer of polyethylene PE antibacterial film layer and the third layer of VMPET film layer substrate surface, so that the main agent and curing agent inside the polyurethane adhesive fully react within a certain period of time to achieve the best composite strength, and at the same time remove the residual solvent with a low boiling point inside the polyurethane adhesive, and finally use the bag making equipment to make packaging film bags that meet the product size requirements.

[0022] Preferably, when the third layer is an AL barrier layer, specifically, a method for preparing an antibacterial packaging material for fresh food is:

[0023] B1. Preparation of the first PET film layer:

[0024] First, the PET resin slices are pre-dried to prevent hydrolysis, and then extruded into amorphous thick slices through a T-die at 280°C in an extruder, quenched by a cooling drum or a coolant, and then subjected to a biaxial stretching treatment, wherein the longitudinal stretching is to preheat the thick slice to 86-87°C and stretch it 3 times along the plane extension direction of the thick slice at this temperature, the transverse stretching preheating temperature is 98-100°C, the stretching temperature is 100-120°C, and the stretching ratio is 2.5-4.0. The film after longitudinal and transverse stretching is heat-set, wherein the heat-setting temperature is 230-240°C, and a biaxially stretched PET film layer with good thermal stability is prepared;

[0025] B2. Preparation of polyethylene PE antibacterial film layer:

[0026] The polyethylene PE antibacterial film layer is processed by a three-layer co-extrusion film blowing machine. The outer layer raw material is a mixture of 10-25% low-density polyethylene and 75-90% linear low-density polyethylene. The middle layer raw material is a mixture of 10-20% low-density polyethylene, 70-85% linear low-density polyethylene, and 2-5% nano-active zinc oxide. The inner layer raw material is a mixture of 10-15% polyethylene, 40-50% linear low-density polyethylene, 30-40% metallocene polyethylene, and 2-5% nano-active zinc oxide.

[0027] The working process of the three-layer co-extrusion film blowing machine when producing the polyethylene PE antibacterial film layer is as follows: first, three layers of different kinds of raw materials are placed in their respective extruders, heated and melted by their respective extruders, and then formed into a melt through the die head. The melt then enters the blowing device. During this process, air is injected into the melt and quickly blown to form a film. The film then enters the cooling system to quickly cool and harden. Finally, the traction and winding device tractions and winds up the hardened film;

[0028] B3. Composite treatment process:

[0029] (1) performing corona treatment on the top surface of the fourth polyethylene PE antibacterial film layer;

[0030] (2) Preparation of aluminum nitride coating: The fourth polyethylene PE antibacterial film layer is placed in a coating chamber containing metal chromium, and the vacuum degree is maintained at less than 1.5×10 -3 Pa, and heated to 135 degrees Celsius, nitrogen and argon were continuously introduced into the device, the sputtering power was set to 12KW, and magnetron sputtering was continued for 5 minutes. Nitrogen reacted with the sputtered chromium atoms to form a nitride layer, which was evenly deposited on the surface of the polyethylene PE antibacterial film layer;

[0031] (2) Aluminum evaporation: The polyethylene PE antibacterial film layer is rolled into a tube, and before evaporation, the tube-shaped polyethylene PE antibacterial film layer is transported and moved by an external unwinding device and a winding device, and the polyethylene PE antibacterial film layer is transported and moved inside a vacuum evaporation machine, and a vacuum pump provided inside the vacuum evaporation machine is used for vacuuming, so that the vacuum degree reaches 1.3×10 -2 ~1.3×10 -3Pa, the evaporation boat is heated to 1300℃~1400℃, and then the aluminum wire with a purity of 99.9% is continuously fed to the evaporation boat, the unwinding speed of the polyethylene PE antibacterial film layer, the winding speed of the polyethylene PE antibacterial film layer, the aluminum wire conveying speed and the evaporation amount of the aluminum wire are adjusted, and the cooling source is turned on to make the aluminum wire continuously melt and evaporate on the evaporation boat, so that a bright aluminum layer is formed on the surface of the nitride layer of the polyethylene PE antibacterial film layer after cooling, the thickness of the aluminum coating layer is 50~150nm, and the width of the aluminum coating film is 800mm~2000mm, forming a composite treatment of the fourth polyethylene PE antibacterial film layer and the third AL barrier layer, and then the aluminum coating layer is subjected to laser thickness measurement. After the aluminum coating layer thickness inspection is qualified, it is flattened and rolled up;

[0032] B4. Composite process treatment:

[0033] (1) The bottom surface of the first PET film layer is subjected to corona treatment, and the second ink film layer is selected from UV inks whose base resin is polyurethane acrylate, and the above-mentioned UV inks are coated and distributed on the surface of the embossing roller of the printing equipment;

[0034] (2) Place the base film roll with the first layer of PET film on the motor reel, place the film in the direction specified by the equipment, and install the base film roll with the fourth layer of polyethylene PE antibacterial film and the third layer of AL barrier layer. Apply UV ink to the bottom of the first layer of PET film through the printing equipment. The coating amount of UV ink is 2.5-3.5g / ㎡. The top of the third layer of AL barrier layer is compounded with UV ink and then sent to the UV curing machine. Set the wavelength of the ultraviolet lamp to 300-400nm and the radiation energy to 50-100J / cm 2 , solidified into a second ink film layer connecting the first PET film layer and the third AL barrier layer. The traction and winding device traction and winding the hardened film, and finally through the bag making equipment into a packaging film bag that meets the size requirements of the product for use.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. In the present invention, on the one hand, the first PET film layer, the second ink film layer, and the third VMPET film layer or AL barrier layer provided inside the packaging material film of the present invention have good mechanical properties of strength, toughness, and barrier properties, and can protect the integrity of the product during transportation and storage;

[0037] 2. In the present invention, on the other hand, the polyethylene PE antibacterial film layer is arranged inside the packaging material film of the present invention, so that the antibacterial components inside the polyethylene PE antibacterial film layer are released lastingly and slowly, so that it can continue to exert its antibacterial effect during the shelf life of the product without causing adverse effects on the human body or the environment due to excessive release. DETAILED DESCRIPTION

[0038] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The present invention provides a technical solution:

[0040] Disclosed is an antibacterial packaging material for fresh food and a preparation method thereof. The distribution structure of the packaging material from top to bottom is: a first PET film layer, a second ink film layer, a third VMPET film layer or an AL barrier layer, and a fourth polyethylene PE antibacterial film layer. The polyethylene PE antibacterial film layer is mainly prepared by a film blowing process and is made into the packaging material by three-layer co-extrusion. The outer layer is mixed with low-density polyethylene in a ratio of 10-25% and linear low-density polyethylene in a ratio of 75-90%. The middle layer is mixed with low-density polyethylene in a ratio of 10-20%, linear low-density polyethylene in a ratio of 70-85%, and an antibacterial agent in a ratio of 2-5%. The inner layer is mixed with polyethylene in a ratio of 10-15%, linear low-density polyethylene in a ratio of 40-50%, metallocene polyethylene in a ratio of 30-40%, and an antibacterial agent in a ratio of 2-5%. The antibacterial agent is nano-active zinc oxide.

[0041] When the third layer is a VMPET film layer, specifically, a method for preparing an antibacterial packaging material for fresh food is as follows:

[0042] A1. Preparation of the first PET film layer:

[0043] First, the PET resin slices are pre-dried to prevent hydrolysis, and then extruded into amorphous thick slices through a T-die at 280°C in an extruder, quenched by a cooling drum or a coolant, and then subjected to a biaxial stretching treatment, wherein the longitudinal stretching is to preheat the thick slice to 86-87°C and stretch it 3 times along the plane extension direction of the thick slice at this temperature, the transverse stretching preheating temperature is 98-100°C, the stretching temperature is 100-120°C, and the stretching ratio is 2.5-4.0. The film after longitudinal and transverse stretching is heat-set, wherein the heat-setting temperature is 230-240°C, and a biaxially stretched PET film layer with good thermal stability is prepared;

[0044] A2. Preparation of the third VMPET film layer:

[0045] (1) Preparation of aluminum nitride coating: half of the biaxially oriented PET film obtained in step A1 above is used as the raw material for secondary processing and is sent into a coating chamber containing metallic chromium, and the vacuum degree is maintained at less than 1.5×10 -3Pa, and heated to 135 degrees Celsius, nitrogen and argon were continuously introduced into the device, the sputtering power was set to 12KW, and magnetron sputtering was continued for 5 minutes. Nitrogen reacted with the sputtered chromium atoms to form a nitride layer, which was evenly deposited on the surface of the biaxially oriented PET film layer;

[0046] (2) Aluminum evaporation: The biaxially oriented PET film layer is rolled into a tube, and before evaporation, the tube-shaped PET film layer is transported and moved by an external unwinding device and a winding device, and the PET film layer is transported and moved inside a vacuum evaporation machine, and a vacuum pump provided inside the vacuum evaporation machine is used for vacuuming, so that the vacuum degree reaches 1.3×10 -2 ~1.3×10 -3 Pa, the evaporation boat is heated to 1300℃~1400℃, and then the aluminum wire with a purity of 99.9% is continuously fed to the evaporation boat, the unwinding speed of the PET film layer, the winding speed of the PET film layer, the aluminum wire feeding speed and the evaporation amount of the aluminum wire are adjusted, and the cooling source is turned on to make the aluminum wire melt and evaporate continuously on the evaporation boat, so that a bright aluminum layer is formed on the surface of the nitride layer of the PET film layer after cooling, the thickness of the aluminum coating layer is 50~150nm, and the width of the aluminum coating film is 800mm~2000mm, so as to form a VMPET film layer, and then the aluminum coating layer is subjected to laser thickness measurement processing, and after the aluminum coating layer thickness inspection is qualified, it is flattened and rolled up;

[0047] A3. Preparation of polyethylene PE antibacterial film layer:

[0048] The polyethylene PE antibacterial film layer is processed by a three-layer co-extrusion film blowing machine. The outer layer raw material is a mixture of 10-25% low-density polyethylene and 75-90% linear low-density polyethylene. The middle layer raw material is a mixture of 10-20% low-density polyethylene, 70-85% linear low-density polyethylene, and 2-5% nano-active zinc oxide. The inner layer raw material is a mixture of 10-15% polyethylene, 40-50% linear low-density polyethylene, 30-40% metallocene polyethylene, and 2-5% nano-active zinc oxide.

[0049] The working process of the three-layer co-extrusion film blowing machine when producing the polyethylene PE antibacterial film layer is as follows: first, three layers of different kinds of raw materials are placed in their respective extruders, heated and melted by their respective extruders, and then formed into a melt through the die head. The melt then enters the blowing device. During this process, air is injected into the melt and quickly blown to form a film. The film then enters the cooling system to quickly cool and harden. Finally, the traction and winding device tractions and winds up the hardened film;

[0050] A4. Composite process treatment:

[0051] (1) The bottom surface of the first PET film layer and the top surface of the third VMPET film layer are subjected to corona treatment, and the second ink film layer uses a UV ink whose base resin is polyurethane acrylate, and the UV ink is coated and distributed on the surface of the embossing roller of the printing equipment;

[0052] (2) A base film roll with the first layer of PET film installed on the motor reel is placed in the direction specified by the equipment, and the base film roll of the third layer of VMPET film is installed. UV ink is applied to the bottom of the first layer of PET film through the inside of the printing equipment. The coating amount of UV ink is 2.5-3.5g / ㎡. The top of the third layer of VMPET film is compounded with UV ink and then sent to the UV curing machine. The wavelength of the ultraviolet lamp is set to 300-400nm and the radiation energy is set to 50-100J / cm 2 , solidified into a second ink film layer connecting the first PET film layer and the third VMPET film layer;

[0053] (3) A base film roll with a fourth polyethylene PE antibacterial film layer installed is arranged on the motor reel, and the film is placed according to the direction specified by the equipment, and the base film roll composed of the first PET film layer, the second ink film layer, and the third VMPET film layer is installed, and then a set of rollers of the rubber roller is lifted so that the base film roll does not contact the rubber roller, polyurethane adhesive is added to the adhesive disk, and the drying oven heater is turned on. The pressure between the rubber roller and the anilox roller is adjusted so that a thin and uniform layer of polyurethane adhesive is coated on the rubber roller. The drying oven heater is a three-stage heating structure, wherein the front end temperature of the drying oven is 50-60°C, the middle end temperature is 60-70°C, and the rear end temperature is 70-80°C. The coating amount of the polyurethane adhesive is 2.5-3.5g / ㎡. When the drying oven temperature reaches the requirement, the cooling equipment and the heat dissipation equipment are used to maintain the drying oven temperature, and the rollers on the rubber roller are lowered to compound the fourth polyethylene PE antibacterial film layer with the third VMPET film layer through the polyurethane adhesive;

[0054] A5. Ripening treatment:

[0055] The film compounded in the above step A4 is placed in a curing room, the temperature inside the curing room is maintained at 45-50°C, a ventilation and exhaust pipe structure is set inside the curing room, and the curing time is 24-36 hours, so that the main agent and curing agent inside the polyurethane adhesive undergo cross-linking reaction, and interact with the fourth layer of polyethylene PE antibacterial film layer and the third layer of VMPET film layer substrate surface, so that the main agent and curing agent inside the polyurethane adhesive fully react within a certain period of time to achieve the best composite strength, and at the same time remove the residual solvent with a low boiling point inside the polyurethane adhesive, and finally use the bag making equipment to make packaging film bags that meet the product size requirements.

[0056] When the third layer is an AL barrier layer, specifically, a method for preparing an antibacterial packaging material for fresh food is as follows:

[0057] B1. Preparation of the first PET film layer:

[0058] First, the PET resin slices are pre-dried to prevent hydrolysis, and then extruded into amorphous thick slices through a T-die at 280°C in an extruder, quenched by a cooling drum or a coolant, and then subjected to a biaxial stretching treatment, wherein the longitudinal stretching is to preheat the thick slice to 86-87°C and stretch it 3 times along the plane extension direction of the thick slice at this temperature, the transverse stretching preheating temperature is 98-100°C, the stretching temperature is 100-120°C, and the stretching ratio is 2.5-4.0. The film after longitudinal and transverse stretching is heat-set, wherein the heat-setting temperature is 230-240°C, and a biaxially stretched PET film layer with good thermal stability is prepared;

[0059] B2. Preparation of polyethylene PE antibacterial film layer:

[0060] The polyethylene PE antibacterial film layer is processed by a three-layer co-extrusion film blowing machine. The outer layer raw material is a mixture of 10-25% low-density polyethylene and 75-90% linear low-density polyethylene. The middle layer raw material is a mixture of 10-20% low-density polyethylene, 70-85% linear low-density polyethylene, and 2-5% nano-active zinc oxide. The inner layer raw material is a mixture of 10-15% polyethylene, 40-50% linear low-density polyethylene, 30-40% metallocene polyethylene, and 2-5% nano-active zinc oxide.

[0061] The working process of the three-layer co-extrusion film blowing machine when producing the polyethylene PE antibacterial film layer is as follows: first, three layers of different kinds of raw materials are placed in their respective extruders, heated and melted by their respective extruders, and then formed into a melt through the die head. The melt then enters the blowing device. During this process, air is injected into the melt and quickly blown to form a film. The film then enters the cooling system to quickly cool and harden. Finally, the traction and winding device tractions and winds up the hardened film;

[0062] B3. Composite treatment process:

[0063] (1) performing corona treatment on the top surface of the fourth polyethylene PE antibacterial film layer;

[0064] (2) Preparation of aluminum nitride coating: The fourth polyethylene PE antibacterial film layer is placed in a coating chamber containing metal chromium, and the vacuum degree is maintained at less than 1.5×10 -3 Pa, and heated to 135 degrees Celsius, nitrogen and argon were continuously introduced into the device, the sputtering power was set to 12KW, and magnetron sputtering was continued for 5 minutes. Nitrogen reacted with the sputtered chromium atoms to form a nitride layer, which was evenly deposited on the surface of the polyethylene PE antibacterial film layer;

[0065] (2) Aluminum evaporation: The polyethylene PE antibacterial film layer is rolled into a tube, and before evaporation, the tube-shaped polyethylene PE antibacterial film layer is transported and moved by an external unwinding device and a winding device, and the polyethylene PE antibacterial film layer is transported and moved inside a vacuum evaporation machine, and a vacuum pump provided inside the vacuum evaporation machine is used for vacuuming, so that the vacuum degree reaches 1.3×10 -2 ~1.3×10 -3 Pa, the evaporation boat is heated to 1300℃~1400℃, and then the aluminum wire with a purity of 99.9% is continuously fed to the evaporation boat, the unwinding speed of the polyethylene PE antibacterial film layer, the winding speed of the polyethylene PE antibacterial film layer, the aluminum wire conveying speed and the evaporation amount of the aluminum wire are adjusted, and the cooling source is turned on to make the aluminum wire continuously melt and evaporate on the evaporation boat, so that a bright aluminum layer is formed on the surface of the nitride layer of the polyethylene PE antibacterial film layer after cooling, the thickness of the aluminum coating layer is 50~150nm, and the width of the aluminum coating film is 800mm~2000mm, forming a composite treatment of the fourth polyethylene PE antibacterial film layer and the third AL barrier layer, and then the aluminum coating layer is subjected to laser thickness measurement. After the aluminum coating layer thickness inspection is qualified, it is flattened and rolled up;

[0066] B4. Composite process treatment:

[0067] (1) The bottom surface of the first PET film layer is subjected to corona treatment, and the second ink film layer is selected from UV inks whose base resin is polyurethane acrylate, and the above-mentioned UV inks are coated and distributed on the surface of the embossing roller of the printing equipment;

[0068] (2) Place the base film roll with the first layer of PET film on the motor reel, place the film in the direction specified by the equipment, and install the base film roll with the fourth layer of polyethylene PE antibacterial film and the third layer of AL barrier layer. Apply UV ink to the bottom of the first layer of PET film through the printing equipment. The coating amount of UV ink is 2.5-3.5g / ㎡. The top of the third layer of AL barrier layer is compounded with UV ink and then sent to the UV curing machine. Set the wavelength of the ultraviolet lamp to 300-400nm and the radiation energy to 50-100J / cm 2 , solidified into a second ink film layer connecting the first PET film layer and the third AL barrier layer. The traction and winding device traction and winding the hardened film, and finally through the bag making equipment into a packaging film bag that meets the size requirements of the product for use.

[0069] Workflow: The present invention provides an antibacterial packaging material for fresh food and a preparation method thereof, which are mainly aimed at the antibacterial packaging treatment of fresh food.

[0070] On the one hand, the first PET film layer, the second ink film layer, and the third VMPET film layer or AL barrier layer arranged inside the packaging material film of the present invention have good mechanical properties of strength, toughness, and barrier properties, and can protect the integrity of the product during transportation and storage.

[0071] On the other hand, by means of the polyethylene PE antibacterial film layer disposed inside the packaging material film of the present invention, the antibacterial components inside the polyethylene PE antibacterial film layer are released lastingly and slowly, so that they continue to exert their antibacterial effects during the shelf life of the product without causing adverse effects on the human body or the environment due to excessive release.

[0072] Among them, the polyethylene PE antibacterial film layer is processed by a three-layer co-extrusion film blowing machine. The outer layer raw material is a mixture of 10-25% low-density polyethylene and 75-90% linear low-density polyethylene. The middle layer raw material is a mixture of 10-20% low-density polyethylene, 70-85% linear low-density polyethylene and 2-5% nano-active zinc oxide. The inner layer raw material is a mixture of 10-15% polyethylene, 40-50% linear low-density polyethylene, 30-40% metallocene polyethylene and 2-5% nano-active zinc oxide. The polyethylene PE antibacterial film layer made by the above-mentioned raw material antibacterial ratio formula can not only achieve the purpose of antibacterial, but also provide better packaging sealing and stability.

[0073] In a humid environment, the antibacterial modified nano-active zinc oxide component inside the polyethylene PE antibacterial film layer will slowly release trace amounts of zinc ions.

[0074] First, because the bacterial surface is negatively charged, the positively charged zinc ions will be adsorbed on the bacterial surface, thereby destroying its charge balance and causing the bacteria to die due to damage to the cell wall.

[0075] Secondly, zinc ions will enter the bacteria, react and combine with the bacterial cellular enzymes, inhibiting the activity of the cellular enzymes and the reproduction and regeneration of bacteria, thereby achieving the effect of killing bacteria.

[0076] Through the above arrangement, the packaging material film of the present invention has better toughness, barrier properties and lasting antibacterial properties than the conventional antibacterial packaging films.

[0077] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A fresh food antibacterial packaging material, characterized in that: The distribution structure of the packaging material from top to bottom is: a first PET film layer, a second ink film layer, a third VMPET film layer or an AL barrier layer, and a fourth polyethylene PE antibacterial film layer, wherein the polyethylene PE antibacterial film layer is mainly prepared by a film blowing process, and is made into the packaging material by three-layer co-extrusion, the outer layer is mixed with 10-25% low-density polyethylene and 75-90% linear low-density polyethylene, the middle layer is mixed with 10-20% low-density polyethylene, 70-85% linear low-density polyethylene, and 2-5% antibacterial agent, the inner layer is mixed with 10-15% polyethylene, 40-50% linear low-density polyethylene, 30-40% metallocene polyethylene, and 2-5% antibacterial agent, and the antibacterial agent is nano-active zinc oxide.

2. The antibacterial packaging material for fresh food according to claim 1, characterized in that: When the third layer is a VMPET film layer, specifically, a method for preparing an antibacterial packaging material for fresh food is as follows: A1. Preparation of the first PET film layer: First, the PET resin slices are pre-dried to prevent hydrolysis, and then extruded into amorphous thick slices through a T-die at 280°C in an extruder, quenched by a cooling drum or a coolant, and then subjected to a biaxial stretching treatment, wherein the longitudinal stretching is to preheat the thick slice to 86-87°C and stretch it 3 times along the plane extension direction of the thick slice at this temperature, the transverse stretching preheating temperature is 98-100°C, the stretching temperature is 100-120°C, and the stretching ratio is 2.5-4.

0. The film after longitudinal and transverse stretching is heat-set, wherein the heat-setting temperature is 230-240°C, and a biaxially stretched PET film layer with good thermal stability is prepared; A2. Preparation of the third VMPET film layer: (1) Preparation of aluminum nitride coating: half of the biaxially oriented PET film obtained in step A1 above is used as the raw material for secondary processing and is sent into a coating chamber containing metallic chromium, and the vacuum degree is maintained at less than 1.5×10 -3 Pa, and heated to 135 degrees Celsius, nitrogen and argon were continuously introduced into the device, the sputtering power was set to 12KW, and magnetron sputtering was continued for 5 minutes. Nitrogen reacted with the sputtered chromium atoms to form a nitride layer, which was evenly deposited on the surface of the biaxially oriented PET film layer; (2) Aluminum evaporation: The biaxially oriented PET film layer is rolled into a tube, and before evaporation, the tube-shaped PET film layer is transported and moved by an external unwinding device and a winding device, and the PET film layer is transported and moved inside a vacuum evaporation machine, and a vacuum pump provided inside the vacuum evaporation machine is used for vacuuming, so that the vacuum degree reaches 1.3×10 -2 ~1.3×10 -3 Pa, the evaporation boat is heated to 1300℃~1400℃, and then the aluminum wire with a purity of 99.9% is continuously fed to the evaporation boat, the unwinding speed of the PET film layer, the winding speed of the PET film layer, the aluminum wire feeding speed and the evaporation amount of the aluminum wire are adjusted, and the cooling source is turned on to make the aluminum wire melt and evaporate continuously on the evaporation boat, so that a bright aluminum layer is formed on the surface of the nitride layer of the PET film layer after cooling, the thickness of the aluminum coating layer is 50~150nm, and the width of the aluminum coating film is 800mm~2000mm, so as to form a VMPET film layer, and then the aluminum coating layer is subjected to laser thickness measurement processing, and after the aluminum coating layer thickness inspection is qualified, it is flattened and rolled up; A3. Preparation of polyethylene PE antibacterial film layer: The polyethylene PE antibacterial film layer is processed by a three-layer co-extrusion film blowing machine. The outer layer raw material is a mixture of 10-25% low-density polyethylene and 75-90% linear low-density polyethylene. The middle layer raw material is a mixture of 10-20% low-density polyethylene, 70-85% linear low-density polyethylene, and 2-5% nano-active zinc oxide. The inner layer raw material is a mixture of 10-15% polyethylene, 40-50% linear low-density polyethylene, 30-40% metallocene polyethylene, and 2-5% nano-active zinc oxide. The working process of the three-layer co-extrusion film blowing machine when producing the polyethylene PE antibacterial film layer is as follows: first, three layers of different kinds of raw materials are placed in their respective extruders, heated and melted by their respective extruders, and then formed into a melt through the die head. The melt then enters the blowing device. During this process, air is injected into the melt and quickly blown to form a film. The film then enters the cooling system to quickly cool and harden. Finally, the traction and winding device tractions and winds up the hardened film; A4. Composite process treatment: (1) The PET film surface of the bottom surface of the first PET film layer and the top surface of the third VMPET film layer are subjected to corona treatment, and the second ink film layer is selected from UV inks whose base resin is polyurethane acrylate, and the above-mentioned UV inks are coated and distributed on the surface of the embossing roller of the printing equipment; (2) A base film roll with the first layer of PET film installed on the motor reel is placed in the direction specified by the equipment, and the base film roll of the third layer of VMPET film is installed. UV ink is applied to the bottom of the first layer of PET film through the inside of the printing equipment. The coating amount of UV ink is 2.5-3.5g / ㎡. The top of the third layer of VMPET film is compounded with UV ink and then sent to the UV curing machine. The wavelength of the ultraviolet lamp is set to 300-400nm and the radiation energy is set to 50-100J / cm 2 , solidified into a second ink film layer connecting the first PET film layer and the third VMPET film layer; (3) A base film roll with a fourth polyethylene PE antibacterial film layer installed is arranged on the motor reel, and the film is placed according to the direction specified by the equipment, and the base film roll composed of the first PET film layer, the second ink film layer, and the third VMPET film layer is installed, and then a set of rollers of the rubber roller is lifted so that the base film roll does not contact the rubber roller, polyurethane adhesive is added to the adhesive disk, and the drying oven heater is turned on. The pressure between the rubber roller and the anilox roller is adjusted so that a thin and uniform layer of polyurethane adhesive is coated on the rubber roller. The drying oven heater is a three-stage heating structure, wherein the front end temperature of the drying oven is 50-60°C, the middle end temperature is 60-70°C, and the rear end temperature is 70-80°C. The coating amount of the polyurethane adhesive is 2.5-3.5g / ㎡. When the drying oven temperature reaches the requirement, the cooling equipment and the heat dissipation equipment are used to maintain the drying oven temperature, and the rollers on the rubber roller are lowered to compound the fourth polyethylene PE antibacterial film layer with the third VMPET film layer through the polyurethane adhesive; A5. Ripening treatment: The film compounded in the above step A4 is placed in a curing room, the temperature inside the curing room is maintained at 45-50°C, a ventilation and exhaust pipe structure is set inside the curing room, and the curing time is 24-36 hours, so that the main agent and curing agent inside the polyurethane adhesive undergo cross-linking reaction, and interact with the fourth layer of polyethylene PE antibacterial film layer and the third layer of VMPET film layer substrate surface, so that the main agent and curing agent inside the polyurethane adhesive fully react within a certain period of time to achieve the best composite strength, and at the same time remove the residual solvent with a low boiling point inside the polyurethane adhesive, and finally use the bag making equipment to make packaging film bags that meet the product size requirements.

3. The antibacterial packaging material for fresh food according to claim 1, characterized in that: When the third layer is an AL barrier layer, specifically, a method for preparing an antibacterial packaging material for fresh food is as follows: B1. Preparation of the first PET film layer: First, the PET resin slices are pre-dried to prevent hydrolysis, and then extruded into amorphous thick slices through a T-die at 280°C in an extruder, quenched by a cooling drum or a coolant, and then subjected to a biaxial stretching treatment, wherein the longitudinal stretching is to preheat the thick slice to 86-87°C and stretch it 3 times along the plane extension direction of the thick slice at this temperature, the transverse stretching preheating temperature is 98-100°C, the stretching temperature is 100-120°C, and the stretching ratio is 2.5-4.

0. The film after longitudinal and transverse stretching is heat-set, wherein the heat-setting temperature is 230-240°C, and a biaxially stretched PET film layer with good thermal stability is prepared; B2. Preparation of polyethylene PE antibacterial film layer: The polyethylene PE antibacterial film layer is processed by a three-layer co-extrusion film blowing machine. The outer layer raw material is a mixture of 10-25% low-density polyethylene and 75-90% linear low-density polyethylene. The middle layer raw material is a mixture of 10-20% low-density polyethylene, 70-85% linear low-density polyethylene, and 2-5% nano-active zinc oxide. The inner layer raw material is a mixture of 10-15% polyethylene, 40-50% linear low-density polyethylene, 30-40% metallocene polyethylene, and 2-5% nano-active zinc oxide. The working process of the three-layer co-extrusion film blowing machine when producing the polyethylene PE antibacterial film layer is as follows: first, three layers of different kinds of raw materials are placed in their respective extruders, heated and melted by their respective extruders, and then formed into a melt through the die head. The melt then enters the blowing device. During this process, air is injected into the melt and quickly blown to form a film. The film then enters the cooling system to quickly cool and harden. Finally, the traction and winding device tractions and winds up the hardened film; B3. Composite treatment process: (1) Corona treatment is performed on the top surface of the fourth polyethylene PE antibacterial film layer; (2) Preparation of aluminum nitride coating: The fourth polyethylene PE antibacterial film layer is placed in a coating chamber containing metal chromium, and the vacuum is maintained at less than 1.5×10 -3 Pa, and heated to 135 degrees Celsius, nitrogen and argon were continuously introduced into the device, the sputtering power was set to 12KW, and magnetron sputtering was continued for 5 minutes. Nitrogen reacted with the sputtered chromium atoms to form a nitride layer, which was evenly deposited on the surface of the polyethylene PE antibacterial film layer; (2) Aluminum evaporation: The polyethylene PE antibacterial film layer is rolled into a tube, and before evaporation, the tube-shaped polyethylene PE antibacterial film layer is transported and moved by an external unwinding device and a winding device, and the polyethylene PE antibacterial film layer is transported and moved inside a vacuum evaporation machine, and a vacuum pump provided inside the vacuum evaporation machine is used for vacuuming, so that the vacuum degree reaches 1.3×10 -2 ~1.3×10 -3 Pa, the evaporation boat is heated to 1300℃~1400℃, and then the aluminum wire with a purity of 99.9% is continuously fed to the evaporation boat, the unwinding speed of the polyethylene PE antibacterial film layer, the winding speed of the polyethylene PE antibacterial film layer, the aluminum wire conveying speed and the evaporation amount of the aluminum wire are adjusted, and the cooling source is turned on to make the aluminum wire continuously melt and evaporate on the evaporation boat, so that a bright aluminum layer is formed on the surface of the nitride layer of the polyethylene PE antibacterial film layer after cooling, the thickness of the aluminum coating layer is 50~150nm, and the width of the aluminum coating film is 800mm~2000mm, forming a composite treatment of the fourth polyethylene PE antibacterial film layer and the third AL barrier layer, and then the aluminum coating layer is subjected to laser thickness measurement. After the aluminum coating layer thickness inspection is qualified, it is flattened and rolled up; B4. Composite process treatment: (1) The bottom surface of the first PET film layer is subjected to corona treatment, and the second ink film layer is selected from UV inks whose base resin is polyurethane acrylate, and the above-mentioned UV inks are coated and distributed on the surface of the embossing roller of the printing equipment; (2) Place the base film roll with the first layer of PET film on the motor reel, place the film in the direction specified by the equipment, and install the base film roll with the fourth layer of polyethylene PE antibacterial film and the third layer of AL barrier layer. Apply UV ink to the bottom of the first layer of PET film through the printing equipment. The coating amount of UV ink is 2.5-3.5g / ㎡. The top of the third layer of AL barrier layer is compounded with UV ink and then sent to the UV curing machine. Set the wavelength of the ultraviolet lamp to 300-400nm and the radiation energy to 50-100J / cm 2 , solidified into a second ink film layer connecting the first PET film layer and the third AL barrier layer. The traction and winding device traction and winding the hardened film, and finally through the bag making equipment into a packaging film bag that meets the size requirements of the product for use.