Preparation process of recyclable liquid washing small package film

Abstract

The application relates to the technical field of packaging materials, in particular to a preparation process of a recyclable liquid washing small packaging film. The recyclable liquid washing small packaging film comprises, from outside to inside, a BOPP outer film printing layer, a VMCPP middle film layer and a CPP inner film layer; the thickness ratio of the BOPP outer film printing layer, the VMCPP middle film layer and the CPP inner film layer is 0.1-1:1-2:1-4; the VMCPP middle film layer comprises, in sequence, a first corona layer, a first intermediate layer, an inner layer and an aluminized layer; the CPP inner film layer comprises, in sequence, a second corona layer, a second intermediate layer and a heat sealing layer; one side of the BOPP printing layer is attached to the first corona layer of the VMCPP middle film layer, and the aluminized layer of the VMCPP middle film layer is attached to the second corona layer of the CPP inner film layer. The application can effectively enhance the degradation effect of the product after being discarded, quickly promote the degradation of microorganisms and ultraviolet rays, has good barrier performance and high heat sealing strength.

Description

Technical Field

[0001] This invention relates to the field of packaging materials technology, and in particular to a process for preparing a recyclable liquid-washable small packaging film. Background Technology

[0002] Packaging films are widely used in various aspects of life, such as food, medicine, and cosmetics, primarily to prevent products from absorbing moisture, becoming damp, or oxidizing, thereby extending their shelf life. The requirements for packaging films differ depending on the application in different fields.

[0003] In recent years, with the continuous and rapid development of the plastics industry, liquid-washable small packaging films have been widely used. Due to their excellent properties such as light weight, high strength, convenience, and low cost, liquid-washable small packaging films have greatly facilitated people's lives.

[0004] Currently, the main packaging materials for liquid washable small packages on the market are PET / PE / VMPET / PE, PET / VMPET / PE, and PET / PE. These are primarily composed of polymers with stable chemical structures and properties. They generally do not degrade on their own and are not easily corroded by bacteria. After disposal, these packaging materials do not rot or decompose, causing serious environmental pollution. Furthermore, the packaging films have poor barrier properties. While methods such as adding inorganic nanomaterials, co-extruding high-barrier resins, coating barrier material layers, and adding aluminum foil are often used to improve their barrier performance, these methods further reduce the biodegradability of the packaging film.

[0005] Therefore, it is imperative to promote high-barrier and environmentally friendly packaging film materials. On the one hand, the high barrier properties can meet the safety and quality requirements of the shelf life and reduce the impact of water vapor and oxygen on the contents of the packaging. On the other hand, it can enhance the biodegradability of the film layer and achieve the degradation effect of the packaging film, which has excellent research prospects. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a process for preparing recyclable liquid washable small packaging films.

[0007] A recyclable liquid-washable small packaging film, comprising, from the outside to the inside: a BOPP outer film printing layer, a VMCPP middle film layer, and a CPP inner film layer; the thickness ratio of the BOPP outer film printing layer, the VMCPP middle film layer, and the CPP inner film layer is 0.1-1:1-2:1-4; the VMCPP middle film layer comprises, from the outside to the inside: a first corona layer, a first intermediate layer, an inner layer, and an aluminized layer; the thickness ratio of the first corona layer, the first intermediate layer, the inner layer, and the aluminized layer is 500-1000:1000-1500:500-1000:2.5-3.5; the CPP inner film layer comprises, from the outside to the inside: a second corona layer, a second intermediate layer, and a heat-sealing layer; the thickness ratio of the second corona layer, the second intermediate layer, and the heat-sealing layer is 1-2:1-5:1-2; wherein, one side of the BOPP printing layer is bonded to the first corona layer of the VMCPP middle film layer, while the aluminized layer of the VMCPP middle film layer is bonded to the second corona layer of the CPP inner film layer.

[0008] Preferably, the first intermediate layer, the inner layer of the VMCPP membrane, and the second intermediate layer of the CPP inner membrane are all made of polypropylene.

[0009] Preferably, the raw materials for the first corona layer of the VMCPP membrane include, by weight: 50-100 parts of polypropylene, 5-15 parts of cyclic olefin copolymer, and 5-10 parts of polyolefin copolymer.

[0010] Preferably, the raw materials for the second corona layer of the CPP inner membrane layer include, by weight: 10-20 parts of polypropylene and 50-100 parts of binary copolymer polypropylene.

[0011] Preferably, the heat-sealing material of the CPP inner film layer includes, by weight: 50-100 parts of polypropylene, 1-2 parts of opening agent, and 1-2 parts of slip agent.

[0012] Preferably, the polypropylene used in the first corona layer material of the VMCPP membrane layer, the second corona layer material of the CPP inner membrane layer, and the heat-sealing layer material of the CPP inner membrane layer is activated polypropylene.

[0013] Preferably, activated polypropylene is prepared by the following steps: Nanographene, cerium chloride, cholesterol, and phospholipids are added to chloroform and stirred for 10-30 minutes. The chloroform is removed by rotary evaporation. The mixture is then added to phosphate buffer solution and sonicated at 30-40°C for 10-20 minutes. Allyltrimethoxysilane is added, and sonication continues at 50-60°C for 1-2 hours. The mixture is dried and pulverized to obtain activated graphene. Polypropylene powder is added to a sealed reactor, a mixed gas is introduced, and the pressure inside the reactor is maintained at 6-10 kPa. The mixture is treated at 60-70°C for 1-2 hours. Under nitrogen protection, activated graphene and chloroform are added, and the mixture is stirred at 120-140°C for 10-30 minutes. The mixture is then cooled, filtered, washed, and vacuum dried.

[0014] More preferably, the mass ratio of nanographene, cerium chloride, cholesterol, phospholipid, allyltrimethoxysilane, and polypropylene is 1-2:1-2:1-5:10-20:0.1-1:50-100.

[0015] More preferably, the concentration of the phosphate buffer solution is 0.01-0.02 mol / L, and its pH is neutral.

[0016] More preferably, the mixture is added to a phosphate buffer solution and then subjected to sonication at a frequency of 5-10 kHz.

[0017] More preferably, the mixed gas includes chlorine and nitrogen, with a volume ratio of chlorine to nitrogen of 1-2:10.

[0018] The above-mentioned method for preparing recyclable liquid washable small packaging films includes the following steps:

[0019] S1. The raw materials of each layer of the VMCPP film layer are produced by three-layer co-extrusion casting method, and then vacuum metallization is performed to obtain the VMCPP film.

[0020] S2. The CPP inner membrane is produced by using a three-layer co-extrusion casting method to produce the raw materials of each layer of the CPP inner membrane.

[0021] S3. The VMCPP middle membrane and CPP inner membrane are combined in a single composite process to obtain a composite membrane, which is then combined with the BOPP outer membrane in an online corona discharge composite process.

[0022] Beneficial effects:

[0023] 1. In this invention, the VMCPP inner film layer and the CPP inner film layer adopt a three-layer structure, which, together with the BOPP outer film printing layer, makes the resulting packaging film use polypropylene resin as the main material from the outer layer, middle layer to the inner layer. After the packaging film is used, it is easy to recycle and has high recycling value, and it can also reduce the environmental pollution of plastics.

[0024] 2. The activated polypropylene used in this invention is a combination of cholesterol and phospholipids to form a phospholipid vesicle bilayer structure. Hydrophobic nano-graphene enters the hydrophobic gap between the bilayer, and cerium chloride is bound to the outer hydrophilic layer and further stabilized by precipitation in the outer structure. Then it is combined with polypropylene, which not only has excellent barrier properties, effectively reducing the impact of water vapor and oxygen on the contents of the packaging, but also has high tensile strength, good puncture resistance, and significantly enhances the dimensional stability of the product.

[0025] This invention employs a phospholipid vesicle bilayer structure to bridge graphene nanoparticles and rare earth cerium, which are simultaneously introduced into a polypropylene matrix. The resulting packaging film not only has excellent film-forming properties but also excellent degradability.

[0026] After the packaging film is discarded, the activated polypropylene, under conditions of water and oxygen, promotes the entry of microorganisms into the interior to decompose the organic matter, resulting in rapid degradation. Experiments have shown that this invention significantly enhances photodegradability, promoting molecular chain breakage and degradation. With its combined effect, the degradation rate reaches over 89% within 90 days, making it environmentally friendly.

[0027] 3. The polypropylene used in the first corona layer, second corona layer, and heat-sealing layer of this invention is activated polypropylene, which not only effectively enhances the degradation effect after the product is disposed of, but also rapidly promotes microbial and ultraviolet degradation. Compared with existing liquid-washable small packaging, this invention can reduce moisture loss during the shelf life of the packaging film and maintain the quality of the contents of the packaging for a longer period of time. At the same time, heat sealing can be achieved using conventional heat sealing temperatures, and the heat sealing strength is high. It is also easy to degrade after disposal, making it green and environmentally friendly. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the cross-sectional structure of the recyclable liquid washable small packaging film obtained by the present invention.

[0029] Figure 1 In the diagram, 1 is the CPP inner film layer, 2 is the VMCPP middle film layer, 3 is the BOPP outer film printing layer, 11 is the heat-sealing layer, 12 is the second intermediate layer, 13 is the second corona layer, 21 is the first corona layer, 22 is the first intermediate layer, 23 is the inner layer, and 24 is the aluminum plating layer.

[0030] Figure 2 The graph shows a comparison of the tensile strength and puncture resistance of the recyclable liquid washable small packaging films obtained in Examples 5, 6, Comparative Example 1, and Comparative Example 2.

[0031] Figure 3 The image shows a comparison of the peel strength and heat-sealing strength of the recyclable liquid-washable small packaging films obtained in Examples 5, 6, Comparative Example 1, and Comparative Example 2.

[0032] Figure 4 The graph shows a comparison of the barrier properties of the recyclable liquid washable small packaging films obtained in Examples 5, 6, Comparative Example 1, and Comparative Example 2.

[0033] Figure 5 The graph shows a comparison of the longitudinal dimensional shrinkage rate and sun exposure degradation rate of the recyclable liquid washable small packaging films obtained in Examples 5, 6, Comparative Example 1, and Comparative Example 2. Detailed Implementation

[0034] The present invention will be further explained below with reference to specific embodiments.

[0035] The cyclic olefin copolymers used below are sourced from Polyplastics Japan, brand name 8007F-600. The polyolefin copolymers used below are sourced from Sumitomo Chemicals Japan, brand name WH303. The binary copolymer polypropylene used below is sourced from Sinopec Korea, brand name FCP80.

[0036] The polypropylene used in the first intermediate layer and inner layer of the VMCPP membrane, and the second intermediate layer of the CPP inner membrane, is sourced from Borealis, with the grade RD265CF. The homopolymer polypropylene is sourced from Lotte Chemicals, South Korea, with the grade JC160.

[0037] The opening agent used below was purchased from Baolide, brand name ABPP10S. The slip agent used below was purchased from Beijing Yalun, brand name SLIP-7. The BOPP outer film used below was purchased from Guofeng Plastics, and is printing grade BOPP.

[0038] Example 1

[0039] A recyclable liquid-washable small packaging film comprises, from the outside to the inside: a BOPP outer film printing layer with a thickness of 2μm, a VMCPP middle film layer, and a CPP inner film layer.

[0040] The VMCPP film layers sequentially include: a first corona layer with a thickness of 5 μm, a first intermediate layer with a thickness of 10 μm, an inner layer with a thickness of 5 μm, and an aluminum-plated layer with a thickness of 25 nm; wherein, the raw materials of the first corona layer include: 50 g of activated polypropylene, 5 g of cyclic olefin copolymer, and 5 g of polyolefin copolymer; while the material of the first intermediate layer and the inner layer is polypropylene.

[0041] The CPP inner membrane layer comprises, in sequence: a second corona layer with a thickness of 10 μm, a second intermediate layer with a thickness of 10 μm, and a heat-sealing layer with a thickness of 10 μm. The second corona layer is composed of activated polypropylene and binary copolymer polypropylene in a mass ratio of 1:5; the heat-sealing layer comprises 50 g of activated polypropylene, 1 g of opening agent, and 1 g of slip agent; and the second intermediate layer is made of polypropylene.

[0042] One side of the BOPP printed layer is bonded to the first corona layer of the VMCPP inner film layer, while the aluminum plating layer of the VMCPP inner film layer is bonded to the second corona layer of the CPP inner film layer.

[0043] The activated polypropylene used above was prepared using the following steps: 1g of nano-graphene, 1g of cerium chloride, 1g of cholesterol, and 10g of phospholipids were added to 5g of chloroform and stirred at 100r / min for 10min. The chloroform was removed by rotary evaporation. The mixture was then added to 20g of a 0.01mol / L, neutral phosphate buffer solution and sonicated at 30℃ for 10min at a frequency of 5kHz. 0.1g of allyltrimethoxysilane was added, and the mixture was sonicated at 50℃ for 1h. After dehydration and drying, the mixture was pulverized to obtain activated graphene. 50g of homopolymer polypropylene powder was added to a sealed reactor, and a mixed gas was introduced while maintaining the pressure inside the reactor at 6kPa. The mixture was treated at 60℃ for 1h, wherein the mixed gas included chlorine and nitrogen, with a chlorine to nitrogen volume ratio of 1:10. Under nitrogen protection, activated graphene and 100g of chloroform were added and stirred at 120℃ for 10min. The mixture was then cooled, filtered, washed, and vacuum dried.

[0044] The above-mentioned method for preparing recyclable liquid washable small packaging films includes the following steps:

[0045] S1. The raw materials of each layer of the VMCPP film layer are produced by three-layer co-extrusion casting method, and then vacuum metallization is performed to obtain the VMCPP film.

[0046] S2. The CPP inner membrane is produced by using a three-layer co-extrusion casting method to produce the raw materials of each layer of the CPP inner membrane.

[0047] S3. The VMCPP middle membrane and CPP inner membrane are combined in a single composite process to obtain a composite membrane, which is then combined with the BOPP outer membrane in an online corona discharge composite process.

[0048] Example 2

[0049] A recyclable liquid-washable small packaging film comprises, from the outside to the inside: a BOPP outer film printing layer with a thickness of 15μm, a VMCPP middle film layer, and a CPP inner film layer.

[0050] The VMCPP film layers sequentially include: a first corona layer with a thickness of 10 μm, a first intermediate layer with a thickness of 15 μm, an inner layer with a thickness of 10 μm, and an aluminum-plated layer with a thickness of 35 nm; wherein, the raw materials of the first corona layer include: 100 g of activated polypropylene, 15 g of cyclic olefin copolymer, and 10 g of polyolefin copolymer; while the material of the first intermediate layer and the inner layer is polypropylene.

[0051] The CPP inner membrane layer comprises, in sequence: a second corona layer with a thickness of 20 μm, a second intermediate layer with a thickness of 45 μm, and a heat-sealing layer with a thickness of 20 μm. The second corona layer is composed of activated polypropylene and binary copolymer polypropylene in a mass ratio of 20:100; the heat-sealing layer comprises 100 g of activated polypropylene, 2 g of opening agent, and 2 g of slip agent; and the second intermediate layer is made of polypropylene.

[0052] One side of the BOPP printed layer is bonded to the first corona layer of the VMCPP inner film layer, while the aluminum plating layer of the VMCPP inner film layer is bonded to the second corona layer of the CPP inner film layer.

[0053] The activated polypropylene used above was prepared using the following steps: 2g of nano-graphene, 2g of cerium chloride, 5g of cholesterol, and 20g of phospholipids were added to 10g of chloroform and stirred at 500r / min for 30min. The chloroform was removed by rotary evaporation. The mixture was then added to 40g of a 0.02mol / L, neutral phosphate buffer solution and sonicated at 40℃ for 20min at a frequency of 10kHz. 1g of allyltrimethoxysilane was added, and the mixture was sonicated at 60℃ for another 2h. After dehydration and drying, the mixture was pulverized to obtain activated graphene. 100g of homopolymer polypropylene powder was added to a sealed reactor, and a mixed gas was introduced while maintaining the pressure inside the reactor at 10kPa. The mixture was treated at 70℃ for 2h, where the mixed gas included chlorine and nitrogen, with a chlorine to nitrogen volume ratio of 2:10. Under nitrogen protection, activated graphene and 200g of chloroform were added and stirred at 140℃ for 30min. The mixture was then cooled, filtered, washed, and vacuum dried.

[0054] The above-mentioned method for preparing recyclable liquid washable small packaging films includes the following steps:

[0055] S1. The raw materials of each layer of the VMCPP film layer are produced by three-layer co-extrusion casting method, and then vacuum metallization is performed to obtain the VMCPP film.

[0056] S2. The CPP inner membrane is produced by using a three-layer co-extrusion casting method to produce the raw materials of each layer of the CPP inner membrane.

[0057] S3. The VMCPP middle membrane and CPP inner membrane are combined in a single composite process to obtain a composite membrane, which is then combined with the BOPP outer membrane in an online corona discharge composite process.

[0058] Example 3

[0059] A recyclable liquid-washable small packaging film comprises, from the outside to the inside: a BOPP outer film printing layer with a thickness of 5μm, a VMCPP middle film layer, and a CPP inner film layer.

[0060] The VMCPP film layers sequentially include: a first corona layer with a thickness of 7 μm, a first intermediate layer with a thickness of 13 μm, an inner layer with a thickness of 7 μm, and an aluminum-plated layer with a thickness of 32 nm; wherein, the raw materials of the first corona layer include: 70 g of activated polypropylene, 12 g of cyclic olefin copolymer, and 7 g of polyolefin copolymer; while the material of the first intermediate layer and the inner layer is polypropylene.

[0061] The CPP inner membrane layer comprises, in sequence: a second corona layer with a thickness of 18 μm, a second intermediate layer with a thickness of 20 μm, and a heat-sealing layer with a thickness of 12 μm. The second corona layer is composed of activated polypropylene and binary copolymer polypropylene in a mass ratio of 18:70; the heat-sealing layer comprises 90 g of activated polypropylene, 1.5 g of opening agent, and 1.5 g of slip agent; and the second intermediate layer is made of polypropylene.

[0062] One side of the BOPP printed layer is bonded to the first corona layer of the VMCPP inner film layer, while the aluminum plating layer of the VMCPP inner film layer is bonded to the second corona layer of the CPP inner film layer.

[0063] The activated polypropylene used above was prepared using the following steps: 1.3g of nano-graphene, 1.8g of cerium chloride, 2g of cholesterol, and 18g of phospholipids were added to 7g of chloroform and stirred at 400r / min for 15min. The chloroform was removed by rotary evaporation, and the mixture was added to 35g of 0.012mol / L neutral phosphate buffer solution. The mixture was sonicated at 37℃ for 12min at a frequency of 9.5kHz. Then, 0.2g of allyltrimethoxysilane was added, and the mixture was sonicated at 58℃. Continue sonication at ℃ for 80 min, dehydrate and dry, pulverize to obtain activated graphene; add 90 g of homopolymer polypropylene powder to a sealed reactor, introduce a mixed gas and maintain the pressure inside the reactor at 7 kPa, and treat at 68℃ for 80 min, wherein the mixed gas includes chlorine and nitrogen, and the volume ratio of chlorine to nitrogen is 1.8:10; under nitrogen protection, add activated graphene and 120 g of chloroform, stir at 125-135℃ for 25 min, cool, filter, wash, and vacuum dry.

[0064] The above-mentioned method for preparing recyclable liquid washable small packaging films includes the following steps:

[0065] S1. The raw materials of each layer of the VMCPP film layer are produced by three-layer co-extrusion casting method, and then vacuum metallization is performed to obtain the VMCPP film.

[0066] S2. The CPP inner membrane is produced by using a three-layer co-extrusion casting method to produce the raw materials of each layer of the CPP inner membrane.

[0067] S3. The VMCPP middle membrane and CPP inner membrane are combined in a single composite process to obtain a composite membrane, which is then combined with the BOPP outer membrane in an online corona discharge composite process.

[0068] Example 4

[0069] A recyclable liquid-washable small packaging film comprises, from the outside to the inside: a BOPP outer film printing layer with a thickness of 13μm, a VMCPP middle film layer, and a CPP inner film layer.

[0070] The VMCPP film layers sequentially include: a first corona layer with a thickness of 9 μm, a first intermediate layer with a thickness of 11 μm, an inner layer with a thickness of 9 μm, and an aluminum-plated layer with a thickness of 28 nm; wherein, the raw materials of the first corona layer include: 90 g of activated polypropylene, 8 g of cyclic olefin copolymer, and 9 g of polyolefin copolymer; while the material of the first intermediate layer and the inner layer is polypropylene.

[0071] The CPP inner membrane layer comprises, in sequence: a second corona layer with a thickness of 12 μm, a second intermediate layer with a thickness of 40 μm, and a heat-sealing layer with a thickness of 18 μm. The second corona layer is composed of activated polypropylene and binary copolymer polypropylene in a mass ratio of 12:90; the heat-sealing layer comprises 70 g of activated polypropylene, 1.5 g of opening agent, and 1.5 g of slip agent; and the second intermediate layer is made of polypropylene.

[0072] One side of the BOPP printed layer is bonded to the first corona layer of the VMCPP inner film layer, while the aluminum plating layer of the VMCPP inner film layer is bonded to the second corona layer of the CPP inner film layer.

[0073] The activated polypropylene used above was prepared using the following steps: 1.7g of nano-graphene, 1.2g of cerium chloride, 4g of cholesterol, and 12g of phospholipids were added to 9g of chloroform and stirred at 200r / min for 25min. The chloroform was removed by rotary evaporation. The mixture was then added to 25g of 0.018mol / L phosphate buffer solution with a neutral pH. The mixture was sonicated at 33℃ for 18min at a frequency of 8.5kHz. 0.8g of allyltrimethoxysilane was added, and the mixture was then sonicated at 52℃. Continue sonication for 100 min, dehydrate and dry, pulverize to obtain activated graphene; add 70 g of homopolymer polypropylene powder to a sealed reactor, introduce a mixed gas and maintain the pressure inside the reactor at 9 kPa, and treat at 62℃ for 100 min, wherein the mixed gas includes chlorine and nitrogen, and the volume ratio of chlorine to nitrogen is 1.2:10; under nitrogen protection, add activated graphene and 120-180 g of chloroform, stir at 135℃ for 15 min, cool, filter, wash, and vacuum dry.

[0074] The above-mentioned method for preparing recyclable liquid washable small packaging films includes the following steps:

[0075] S1. The raw materials of each layer of the VMCPP film layer are produced by three-layer co-extrusion casting method, and then vacuum metallization is performed to obtain the VMCPP film.

[0076] S2. The CPP inner membrane is produced by using a three-layer co-extrusion casting method to produce the raw materials of each layer of the CPP inner membrane.

[0077] S3. The VMCPP middle membrane and CPP inner membrane are combined in a single composite process to obtain a composite membrane, which is then combined with the BOPP outer membrane in an online corona discharge composite process.

[0078] Example 5

[0079] A recyclable liquid-washable small packaging film comprises, from the outside to the inside: a BOPP outer film printing layer with a thickness of 10μm, a VMCPP middle film layer, and a CPP inner film layer.

[0080] The VMCPP film layers sequentially include: a first corona layer with a thickness of 8μm, a first intermediate layer with a thickness of 12μm, an inner layer with a thickness of 8μm, and an aluminum-plated layer with a thickness of 30nm; wherein, the raw materials of the first corona layer include: 80g of activated polypropylene, 10g of cyclic olefin copolymer, and 8g of polyolefin copolymer; while the material of the first intermediate layer and the inner layer is polypropylene.

[0081] The CPP inner membrane layer comprises, in sequence: a second corona layer with a thickness of 15 μm, a second intermediate layer with a thickness of 30 μm, and a heat-sealing layer with a thickness of 15 μm. The second corona layer is composed of activated polypropylene and binary copolymer polypropylene in a mass ratio of 15:80; the heat-sealing layer comprises 80 g of activated polypropylene, 1.5 g of opening agent, and 1.5 g of slip agent; and the second intermediate layer is made of polypropylene.

[0082] One side of the BOPP printed layer is bonded to the first corona layer of the VMCPP inner film layer, while the aluminum plating layer of the VMCPP inner film layer is bonded to the second corona layer of the CPP inner film layer.

[0083] The activated polypropylene used above was prepared using the following steps: 1.5g of nano-graphene, 1.5g of cerium chloride, 3g of cholesterol, and 15g of phospholipids were added to 8g of chloroform and stirred at 300r / min for 20min. The chloroform was removed by rotary evaporation. The mixture was then added to 30g of 0.015mol / L phosphate buffer solution with a neutral pH. The mixture was sonicated at 35℃ for 15min at a frequency of 9kHz. 0.5g of allyltrimethoxysilane was then added, and the mixture was sonicated at 5℃ for 15min. Continue sonication at 5℃ for 90 min, dehydrate and dry, pulverize to obtain activated graphene; add 80g of homopolymer polypropylene powder to a sealed reactor, introduce a mixed gas and maintain the pressure inside the reactor at 8kPa, and treat at 65℃ for 90 min, wherein the mixed gas includes chlorine and nitrogen, and the volume ratio of chlorine to nitrogen is 1.5:10; under nitrogen protection, add activated graphene and 150g of chloroform, stir at 130℃ for 20 min, cool, filter, wash, and vacuum dry.

[0084] The above-mentioned method for preparing recyclable liquid washable small packaging films includes the following steps:

[0085] S1. The raw materials of each layer of the VMCPP film layer are produced by three-layer co-extrusion casting method, and then vacuum metallization is performed to obtain the VMCPP film.

[0086] S2. The CPP inner membrane is produced by using a three-layer co-extrusion casting method to produce the raw materials of each layer of the CPP inner membrane.

[0087] S3. The VMCPP middle membrane and CPP inner membrane are composited in a single composite process to obtain a composite membrane, which is then composited with the BOPP outer membrane in an online corona discharge composite process.

[0088] Example 6

[0089] A recyclable liquid-washable small packaging film comprises, from the outside to the inside: a BOPP outer film printing layer with a thickness of 10μm, a VMCPP middle film layer, and a CPP inner film layer.

[0090] The VMCPP film layers sequentially include: a first corona layer with a thickness of 8μm, a first intermediate layer with a thickness of 12μm, an inner layer with a thickness of 8μm, and an aluminum-plated layer with a thickness of 30nm; wherein, the raw materials of the first corona layer include: 80g of polypropylene, 10g of cyclic olefin copolymer, and 8g of polyolefin copolymer; while the material of the first intermediate layer and the inner layer is polypropylene.

[0091] The CPP inner membrane layer comprises, in sequence: a second corona layer with a thickness of 15 μm, a second intermediate layer with a thickness of 30 μm, and a heat-sealing layer with a thickness of 15 μm. The second corona layer is composed of activated polypropylene and binary copolymer polypropylene in a mass ratio of 15:80; the heat-sealing layer comprises 80 g of activated polypropylene, 1.5 g of opening agent, and 1.5 g of slip agent; and the second intermediate layer is made of polypropylene.

[0092] One side of the BOPP printed layer is bonded to the first corona layer of the VMCPP inner film layer, while the aluminum plating layer of the VMCPP inner film layer is bonded to the second corona layer of the CPP inner film layer.

[0093] The activated polypropylene used above was prepared using the following steps: 1.5g of nano-graphene, 1.5g of cerium chloride, 3g of cholesterol, and 15g of phospholipids were added to 8g of chloroform and stirred at 300r / min for 20min. The chloroform was removed by rotary evaporation. The mixture was then added to 30g of 0.015mol / L phosphate buffer solution with a neutral pH. The mixture was sonicated at 35℃ for 15min at a frequency of 9kHz. 0.5g of allyltrimethoxysilane was then added, and the mixture was sonicated at 5℃ for 15min. Continue sonication at 5℃ for 90 min, dehydrate and dry, pulverize to obtain activated graphene; add 80g of homopolymer polypropylene powder to a sealed reactor, introduce a mixed gas and maintain the pressure inside the reactor at 8kPa, and treat at 65℃ for 90 min, wherein the mixed gas includes chlorine and nitrogen, and the volume ratio of chlorine to nitrogen is 1.5:10; under nitrogen protection, add activated graphene and 150g of chloroform, stir at 130℃ for 20 min, cool, filter, wash, and vacuum dry.

[0094] The above-mentioned method for preparing recyclable liquid washable small packaging films includes the following steps:

[0095] S1. The raw materials of each layer of the VMCPP film layer are produced by three-layer co-extrusion casting method, and then vacuum metallization is performed to obtain the VMCPP film.

[0096] S2. The CPP inner membrane is produced by using a three-layer co-extrusion casting method to produce the raw materials of each layer of the CPP inner membrane.

[0097] S3. The VMCPP middle membrane and CPP inner membrane are combined in a single composite process to obtain a composite membrane, which is then combined with the BOPP outer membrane in an online corona discharge composite process.

[0098] Comparative Example 1

[0099] A recyclable liquid-washable small packaging film comprises, from the outside to the inside: a BOPP outer film printing layer with a thickness of 10μm, a VMCPP middle film layer, and a CPP inner film layer.

[0100] The VMCPP film layers sequentially include: a first corona layer with a thickness of 8μm, a first intermediate layer with a thickness of 12μm, an inner layer with a thickness of 8μm, and an aluminum-plated layer with a thickness of 30nm; wherein, the raw materials of the first corona layer include: 80g of activated polypropylene, 10g of cyclic olefin copolymer, and 8g of polyolefin copolymer; while the material of the first intermediate layer and the inner layer is polypropylene.

[0101] The CPP inner membrane layer comprises, in sequence: a second corona layer with a thickness of 15 μm, a second intermediate layer with a thickness of 30 μm, and a heat-sealing layer with a thickness of 15 μm. The second corona layer is composed of activated polypropylene and binary copolymer polypropylene in a mass ratio of 15:80; the heat-sealing layer comprises 80 g of activated polypropylene, 1.5 g of opening agent, and 1.5 g of slip agent; and the second intermediate layer is made of polypropylene.

[0102] One side of the BOPP printed layer is bonded to the first corona layer of the VMCPP inner film layer, while the aluminum plating layer of the VMCPP inner film layer is bonded to the second corona layer of the CPP inner film layer.

[0103] The activated polypropylene used above was prepared using the following steps: 1.5g of nano-graphene and 1.5g of cerium chloride were added to 8g of chloroform, stirred at 300r / min for 20min, the chloroform was removed by rotary evaporation, and the mixture was added to 30g of 0.015mol / L neutral phosphate buffer solution. The mixture was sonicated at 35℃ for 15min at a frequency of 9kHz, and then 0.5g of allyltrimethoxysilane was added. The mixture was then sonicated at 55℃ for another 90min. Dehydrate, dry, and pulverize to obtain activated graphene; add 80g of homopolymer polypropylene powder to a sealed reactor, introduce a mixed gas and maintain the pressure inside the reactor at 8kPa, and treat at 65℃ for 90min, wherein the mixed gas includes chlorine and nitrogen, and the volume ratio of chlorine to nitrogen is 1.5:10; under nitrogen protection, add activated graphene, 3g cholesterol, 15g phospholipid, and 150g chloroform, stir at 130℃ for 20min, cool, filter, wash, and vacuum dry.

[0104] The above-mentioned method for preparing recyclable liquid washable small packaging films includes the following steps:

[0105] S1. The raw materials of each layer of the VMCPP film layer are produced by three-layer co-extrusion casting method, and then vacuum metallization is performed to obtain the VMCPP film.

[0106] S2. The CPP inner membrane is produced by using a three-layer co-extrusion casting method to produce the raw materials of each layer of the CPP inner membrane.

[0107] S3. The VMCPP middle membrane and CPP inner membrane are combined in a single composite process to obtain a composite membrane, which is then combined with the BOPP outer membrane in an online corona discharge composite process.

[0108] Comparative Example 2

[0109] A recyclable liquid-washable small packaging film comprises, from the outside to the inside: a BOPP outer film printing layer with a thickness of 10μm, a VMCPP middle film layer, and a CPP inner film layer.

[0110] The VMCPP film layers sequentially include: a first corona layer with a thickness of 8μm, a first intermediate layer with a thickness of 12μm, an inner layer with a thickness of 8μm, and an aluminum-plated layer with a thickness of 30nm; wherein, the raw materials of the first corona layer include: 80g of activated polypropylene, 10g of cyclic olefin copolymer, and 8g of polyolefin copolymer; while the material of the first intermediate layer and the inner layer is polypropylene.

[0111] The CPP inner membrane layer comprises, in sequence: a second corona layer with a thickness of 15 μm, a second intermediate layer with a thickness of 30 μm, and a heat-sealing layer with a thickness of 15 μm. The second corona layer is composed of activated polypropylene and binary copolymer polypropylene in a mass ratio of 15:80; the heat-sealing layer comprises 80 g of activated polypropylene, 1.5 g of opening agent, and 1.5 g of slip agent; and the second intermediate layer is made of polypropylene.

[0112] One side of the BOPP printed layer is bonded to the first corona layer of the VMCPP inner film layer, while the aluminum plating layer of the VMCPP inner film layer is bonded to the second corona layer of the CPP inner film layer.

[0113] The activated polypropylene used above was prepared using the following steps: 1.5g of cerium chloride, 3g of cholesterol, and 15g of phospholipids were added to 8g of chloroform and stirred at 300r / min for 20min. The chloroform was removed by rotary evaporation. The mixture was then added to 30g of 0.015mol / L phosphate buffer solution with a neutral pH. The mixture was sonicated at 35℃ for 15min at a frequency of 9kHz. 0.5g of allyltrimethoxysilane was added, and the mixture was sonicated again at 55℃ for 90min. The pretreated cerium oxide was dehydrated, dried, and pulverized. 80g of homopolymer polypropylene powder was added to a sealed reactor, a mixed gas was introduced and the pressure inside the reactor was maintained at 8kPa, and the reactor was treated at 65℃ for 90min. The mixed gas included chlorine and nitrogen, with a chlorine to nitrogen volume ratio of 1.5:10. Under nitrogen protection, the pretreated cerium oxide, 1.5g of nano-graphene, and 150g of chloroform were added, and the reactor was stirred at 130℃ for 20min. The mixture was then cooled, filtered, washed, and vacuum dried.

[0114] The above-mentioned method for preparing recyclable liquid washable small packaging films includes the following steps:

[0115] S1. The raw materials of each layer of the VMCPP film layer are produced by three-layer co-extrusion casting method, and then vacuum metallization is performed to obtain the VMCPP film.

[0116] S2. The CPP inner membrane is produced by using a three-layer co-extrusion casting method to produce the raw materials of each layer of the CPP inner membrane.

[0117] S3. The VMCPP middle membrane and CPP inner membrane are combined in a single composite process to obtain a composite membrane, which is then combined with the BOPP outer membrane in an online corona discharge composite process.

[0118] The mechanical properties of the recyclable liquid-washable small packaging films obtained in Examples 5, 6, Comparative Example 1, and Comparative Example 2 were determined as follows:

[0119] (1) Tensile strength test was performed in accordance with GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for thin plastics and sheets";

[0120] (2) Puncture resistance and peel strength were tested in accordance with GB / T 10004-2008 "Dry lamination and extrusion lamination of plastic composite films and bags for packaging".

[0121] (3) The heat sealing strength of the plastic film packaging bag was determined in accordance with QB / T 2358-1998 "Test Method for Heat Sealing Strength of Plastic Film Packaging Bag", and the heat sealing temperature was set to 120℃.

[0122] like Figure 2 and Figure 3 As shown, the recyclable liquid washable small packaging film obtained in Example 5 has the highest tensile strength, puncture resistance, peel strength and heat sealing strength, which are superior to Example 6 and Comparative Examples 1-2 (P<0.05).

[0123] The barrier properties of the recyclable liquid-washable small packaging films obtained in Examples 5, 6, Comparative Example 1, and Comparative Example 2 were determined as follows:

[0124] (4) The water vapor transmission rate was tested according to the weight gain method in GB / T 1037-2021 "Determination of Water Vapor Transmission Performance of Plastic Films and Sheets by Cup Weight Gain and Weight Loss Method". The test temperature was 38°C, the humidity was 90%RH, the preheating time was 2h, the rotation interval was 10min, and 3 parallel tests were set up for each group.

[0125] (5) The oxygen permeability test was conducted in accordance with GB / T 1038.1-2022 "Test Method for Gas Permeability of Plastic Films and Sheets Part 1: Differential Pressure Method". The test temperature was 23°C, the humidity was 50%RH, and the vacuum time was 4h. Ensure that the sample surface is free of contamination and scratches, and set up 3 parallel samples for each group.

[0126] like Figure 4 As shown, the recyclable liquid-washable small packaging film obtained in Example 5 had the lowest water vapor permeability and oxygen permeability, which was better than that of Example 6 and Comparative Examples 1-2 (P<0.05), confirming that the recyclable liquid-washable small packaging film obtained in Example 5 had the best barrier performance.

[0127] The recyclable liquid-washable small packaging films obtained in Examples 5, 6, Comparative Example 1, and Comparative Example 2 were placed in an oven at 120°C for 30 minutes, and the longitudinal dimensional shrinkage rate of each group of samples was measured.

[0128] like Figure 5 As shown, the longitudinal dimensional shrinkage rate of the recyclable liquid washable small packaging film obtained in Example 5 was the smallest, similar to that of the recyclable liquid washable small packaging film obtained in Example 6, with no significant difference, but better than Comparative Examples 1-2 (P<0.05).

[0129] The recyclable washable small packaging films obtained in Examples 5, 6, Comparative Example 1, and Comparative Example 2 were fixed at all four sides and laid flat on the outdoor soil surface, with no obstructions near the test site. The test period was from July 1st to September 28th of the same year, totaling 90 days. This included 68 sunny days, 12 cloudy days, 3 overcast days, and 7 rainy days, with an average temperature of 35.7℃. The tensile strength of each group of samples was measured before and after the test, and the tensile strength loss rate was used to characterize the degradation rate due to sun exposure.

[0130] Tensile strength loss rate = [1 - (final tensile strength ÷ initial tensile strength)] × 100%

[0131] like Figure 5 As shown, the recyclable liquid-washable small packaging film obtained in Example 5 had the highest tensile strength loss rate under exposure, which was higher than that of Example 6 and Comparative Examples 1-2 (P<0.05), confirming that the recyclable liquid-washable small packaging film obtained in Example 5 had the best degradation performance.

[0132] The applicant believes the above results are due to the following: The activated polypropylene used in this invention employs a combination of cholesterol and phospholipids to form a phospholipid vesicle bilayer structure. Hydrophobic nano-graphene enters the hydrophobic gaps between the bilayers, while cerium chloride is bound to the outer hydrophilic layer and further stabilized through precipitation within the outer structure before combining with the polypropylene. This not only results in excellent barrier properties, effectively reducing the impact of water vapor and oxygen on the packaged contents, but also provides high tensile strength, good puncture resistance, and significantly enhanced dimensional stability of the product. This invention uses a phospholipid vesicle bilayer structure to bridge nano-graphene and rare earth cerium, simultaneously introducing them into the polypropylene matrix. The resulting packaging film not only possesses excellent film-forming properties but also excellent degradability. When the packaging film is discarded, the activated polypropylene, under conditions of water and oxygen, promotes the entry of microorganisms to decompose the organic matter, resulting in rapid degradation.

[0133] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A recyclable liquid-washable small packaging film, characterized in that, From the outside in, it includes: BOPP outer film printing layer, VMCPP middle film layer, and CPP inner film layer; The thickness ratio of the BOPP outer film printing layer, the VMCPP middle film layer, and the CPP inner film layer is 0.1-1:1-2:1-4; The VMCPP film layers sequentially include: a first corona layer, a first intermediate layer, an inner layer, and an aluminum-plated layer; the thickness ratio of the first corona layer, the first intermediate layer, the inner layer, and the aluminum-plated layer is 500-1000:1000-1500:500-1000:2.5-3.5; The CPP inner membrane layer comprises, in sequence, a second corona layer, a second intermediate layer, and a heat-sealing layer; the thickness ratio of the second corona layer, the second intermediate layer, and the heat-sealing layer is 1-2:1-5:1-2; In this case, the BOPP printed layer is bonded to the first corona layer of the VMCPP middle film layer, while the aluminum plating layer of the VMCPP middle film layer is bonded to the second corona layer of the CPP inner film layer. The raw materials for the first corona layer of the VMCPP membrane, by weight, include: 50-100 parts of polypropylene, 5-15 parts of cyclic olefin copolymer, and 5-10 parts of polyolefin copolymer. The raw materials for the second corona layer of the CPP inner membrane layer include, by weight: 10-20 parts of polypropylene and 50-100 parts of binary copolymer polypropylene. The heat-sealing material of the CPP inner film layer includes, by weight: 50-100 parts of polypropylene, 1-2 parts of opening agent, and 1-2 parts of slip agent. The polypropylene used in the first corona layer of the VMCPP membrane, the second corona layer of the CPP inner membrane, and the heat-sealing layer of the CPP inner membrane is activated polypropylene. Activated polypropylene is prepared by the following steps: Nanographene, cerium chloride, cholesterol, and phospholipids are added to chloroform and stirred for 10-30 minutes. The chloroform is removed by rotary evaporation. The chloroform is then added to phosphate buffer solution and sonicated at 30-40°C for 10-20 minutes. Allyltrimethoxysilane is added and sonicated at 50-60°C for 1-2 hours. The mixture is then dried and pulverized to obtain activated graphene. Polypropylene powder is added to a sealed reactor, and a mixed gas is introduced while maintaining the pressure inside the reactor at 6-10 kPa. The mixture is then treated at 60-70°C for 1-2 hours. Under nitrogen protection, activated graphene and chloroform are added and stirred at 120-140°C for 10-30 minutes. The mixture is then cooled, filtered, washed, and vacuum dried.

2. The recyclable liquid-washable small packaging film according to claim 1, characterized in that, The first intermediate layer and inner layer of the VMCPP membrane, as well as the second intermediate layer of the CPP inner membrane, are all made of polypropylene.

3. The recyclable liquid-washable small packaging film according to claim 1, characterized in that, The mass ratio of nanographene, cerium chloride, cholesterol, phospholipids, allyltrimethoxysilane, and polypropylene is 1-2:1-2:1-5:10-20:0.1-1:50-100.

4. The recyclable liquid-washable small packaging film according to claim 1, characterized in that, The concentration of the phosphate buffer is 0.01-0.02 mol / L, and its pH is neutral. After being added to the phosphate buffer, it is subjected to sonication at a frequency of 5-10 kHz.

5. The recyclable liquid-washable small packaging film according to claim 1, characterized in that, The mixed gas includes chlorine and nitrogen, with a volume ratio of chlorine to nitrogen of 1-2:

10.

6. A method for preparing a recyclable liquid-washable small packaging film as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. The raw materials of each layer of the VMCPP film layer are produced by three-layer co-extrusion casting method, and then vacuum metallization is performed to obtain the VMCPP film. S2. The CPP inner membrane is produced by using a three-layer co-extrusion casting method to produce the raw materials of each layer of the CPP inner membrane. S3. The VMCPP middle membrane and CPP inner membrane are composited in a single composite process to obtain a composite membrane, which is then composited with the BOPP outer membrane in an online corona discharge composite process.

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