An easy-to-tear composite film and a method for preparing the same

Abstract

The application relates to the field of composite films, and particularly discloses an easy-to-tear composite film and a preparation method thereof. The easy-to-tear composite film comprises, from top to bottom, a printing film, a first adhesive layer, an aluminum foil intermediate layer, a second adhesive layer and an inner layer heat-seal polyethylene film; wherein the printing film is a polyethylene terephthalate film; the first adhesive layer comprises the following raw materials in parts by weight: 75-80 parts of a modified polyurethane resin, 3-4 parts of a hyperbranched polymer, 2-4 parts of a curing agent, 70-80 parts of ethyl acetate and 0.5-0.8 parts of methyl methacrylate phosphate; in addition, the easy-to-tear composite film prepared by the application has good impact resistance, good anti-peeling performance and good moisture resistance.

Description

Technical Field

[0001] This application relates to the field of composite films, and more specifically, to an easy-tear composite film and a method for preparing the same. Background Technology

[0002] As people's living standards improve, the requirements for packaging are also constantly increasing. For example, packaging materials need to have good strength, be not easily torn, and avoid contamination of the internal products by external bacteria. At the same time, packaging materials are also required to be tear-resistant to ensure ease of use.

[0003] Existing easy-tear packaging composite film structures are generally aluminum-plastic multilayer composite structures. The production process involves using a polyethylene terephthalate (PET) film layer or a biaxially oriented polypropylene (BOP) film layer as the printing film. First, polyurethane adhesive is coated onto the lower surface of the printed film using a dry lamination method. Then, it is hot-pressed with an intermediate aluminum foil layer to form a semi-finished composite film. The semi-finished composite film is then placed in an oven for 24 hours to allow the polyurethane adhesive to fully cure at a constant temperature. Next, polyurethane adhesive is coated onto the lower surface of the aluminum foil using a dry lamination or solvent-free lamination method. The semi-finished composite film is then laminated with an inner heat-sealed polyethylene film. The composite film is then placed in an oven for a second curing process of 48 hours. After cooling for 12 hours, the composite film is then damaged using a laser method to create numerous mechanical holes or easy-tear lines, thus achieving the easy-tear effect.

[0004] The existing easy-tear packaging composite film is prone to peeling and tearing from the intermediate aluminum foil when subjected to external impact or deep forming, which affects the yield rate of production. Summary of the Invention

[0005] To improve the bonding strength between the printed film and the intermediate aluminum foil and the impact resistance of the composite film, this application provides an easy-tear composite film and its preparation method.

[0006] In a first aspect, this application provides an easy-tear composite film, employing the following technical solution:

[0007] An easy-tear composite film, from top to bottom, includes a printed film, a first adhesive layer, an aluminum foil intermediate layer, a second adhesive layer, and an inner heat-sealable polyethylene film;

[0008] The printed film is a polyethylene terephthalate film.

[0009] The first adhesive layer comprises the following raw materials in parts by weight: 75-80 parts modified polyurethane resin, 3-4 parts hyperbranched polymer, 2-4 parts curing agent, 70-80 parts ethyl acetate and 0.5-0.8 parts phosphate methacrylate.

[0010] By adopting the above technical solution, this application uses polyurethane resin as the base resin of the first adhesive layer. Polyurethane resin has high reactivity and can chemically react with the aluminum surface or form physical adsorption, thereby achieving stable adhesion. Polyurethane resin has strong adhesion and good toughness, and can withstand certain shear and impact forces, thereby reducing the possibility of tearing when the printed film and aluminum foil interlayer are subjected to impact. This application also modifies the polyurethane resin to further enhance its adhesion, impact resistance, mechanical properties, and stability.

[0011] The first adhesive layer in this application also employs a hyperbranched polymer. The numerous cavities within the hyperbranched polymer facilitate the plastic deformation of the polyurethane resin, thereby toughening the adhesive layer. Its abundant active functional groups can participate in the polyurethane resin curing system, enhancing the interfacial interaction with aluminum, thus strengthening the adhesion between the aluminum foil interlayer and the printed film, and also improving the impact resistance of the composite film. Furthermore, the hyperbranched polymer contains a large number of end groups and branching points, which can provide numerous crosslinking points, thereby enhancing the crosslinking density and network structure of the resin. Therefore, the use of hyperbranched polymers can significantly improve the mechanical properties, thermal stability, chemical stability, and other characteristics of the resin.

[0012] The first adhesive layer in this application also contains phosphate methacrylate. Phosphate methacrylate can form a stable coordination compound with aluminum, thereby improving the adhesion of the first adhesive layer. Phosphate methacrylate can also improve the solubility of the hyperbranched polymer, making it easier to disperse and stabilize in the resin system. In addition, phosphate methacrylate can improve the film-forming properties of the modified polyurethane resin, making the formed first adhesive layer more uniform, smooth, and with good gloss. The introduction of phosphate methacrylate can also improve the stability of the modified polyurethane resin. Therefore, the introduction of phosphate methacrylate into the modified polyurethane system can improve its adhesion, film-forming properties, and emulsion stability.

[0013] In summary, the modified polyurethane resin, hyperbranched polymer, and phosphate methacrylate in this application can synergistically improve the adhesion, mechanical properties, impact resistance, and stability of the first adhesive layer.

[0014] Preferably, the preparation of the modified polyurethane resin includes the following steps:

[0015] S1: Place 25-35 parts by weight of polyester polyol, 21-24 parts by weight of isophor diisocyanate, 2-3 parts by weight of triethylenediamine and 13-15 parts by weight of silicone oil in a reactor and heat to 90-120°C. React for 2-3 hours. After the reaction is complete, cool to room temperature to obtain the prepolymer material.

[0016] S2: Mix the prepolymer material from step S1 with 5-7 parts by weight of N-methyldiethanolamine, heat to 65-70℃, react for 2-2.5 hours, cool to 30-35℃, add glacial acetic acid to neutralize to pH 5-6, then add 40-50 parts by weight of acetone to dilute, and remove the acetone solvent under vacuum to obtain the modified polyurethane resin.

[0017] By adopting the above technical solution, this application introduces organosilicon into polyurethane resin, which can improve the hydrophobicity, stability and flexibility of the first adhesive layer. On the one hand, the hydrophobic properties of organosilicon groups make it difficult for water to penetrate between the printed film and the first adhesive layer, thereby improving the moisture resistance and stability of the composite film. On the other hand, it can also improve the flexibility of the first adhesive layer, thereby improving the impact resistance of the first adhesive layer.

[0018] Preferably, the silicone oil is MA-5232 silicone oil.

[0019] By adopting the above technical solution, MA-5232 silicone oil has good compatibility with the polyurethane system and high reactivity, which can further enhance the stability and impact resistance of the first adhesive layer.

[0020] Preferably, the hyperbranched polymer comprises the following preparation steps:

[0021] Mix 20-30 parts by weight of N,N-dimethylformamide, 1.5-2 parts by weight of phthalic anhydride and 1.4-1.6 parts by weight of pentaerythritol, heat to 120-125℃, and polymerize for 4-8 hours. Then add 3-15 parts by weight of diethylenetriamine and react at 110-120℃ for 7-8 hours to obtain a hyperbranched polymer.

[0022] By adopting the above technical solution, this application uses the above-mentioned polycondensation reaction and amine end-capping agent to obtain hyperbranched polymer. This hyperbranched polymer contains a large number of end groups, has good compatibility with the system, and high reactivity, which is beneficial to improve the crosslinking of the resin system and enhance the stability and impact resistance of the first adhesive layer.

[0023] Preferably, the weight ratio of the modified polyurethane resin, the hyperbranched polymer, and the phosphate methacrylate is (77-78):(3.2-3.5):(0.6-0.7).

[0024] By adopting the above technical solution, this application further controls the weight ratio of modified polyurethane resin, hyperbranched polymer and phosphate methacrylate, so that the three can further exert a synergistic effect, thereby further improving the bonding performance and impact resistance of the first adhesive layer.

[0025] Preferably, the aluminum foil interlayer is further pretreated, and the pretreatment includes the following steps:

[0026] S1: Aluminum foil is soaked in a 6wt% to 8wt% sodium hydroxide solution for 5 to 15 minutes and then removed and dried;

[0027] S2: The dried aluminum foil is subjected to sanding treatment, wherein the pressure of the sanding roller is 0.2-0.4 MPa and the traction speed is 100-120 m / min, so that micropores are formed on the surface of the aluminum foil, and the pre-treated aluminum foil intermediate layer is obtained.

[0028] By adopting the above technical solution, aluminum foil is very easy to form a passivated aluminum oxide film in the air, which affects the function of the first adhesive layer. In this application, the aluminum foil is first soaked in a low concentration sodium hydroxide solution to remove surface impurities and aluminum oxide film, and then the aluminum foil is sanded to form micropores, which are similar to "anchor points", further enabling the modified polyurethane resin to be tightly bonded to the surface of the aluminum foil.

[0029] Preferably, the pretreated aluminum foil is further modified. The modification process includes the following steps: mixing 0.5-1 parts by weight of polysiloxane, 5-7 parts by weight of nano-silica and 70-80 parts by weight of water to form a modification solution, immersing the aluminum foil in the modification solution, taking it out, and drying it to obtain the modified aluminum foil.

[0030] By adopting the above technical solution, polysiloxane can be adsorbed on the surface of aluminum foil, improving the hydrophobicity of the aluminum foil and facilitating the bonding between the aluminum foil and the organosilicon-modified polyurethane resin, thereby improving the adhesion between the aluminum foil and the first adhesive layer. Nano-silica particles are small and have extremely high surface energy, resulting in good adhesion to the aluminum foil surface. The adhesion of nano-silica to the aluminum foil surface increases the roughness of the aluminum foil, thereby increasing the bonding force between the first adhesive layer and the aluminum foil. Polysiloxane and nano-titanium dioxide synergistically improve the adhesion between the first adhesive layer and the aluminum foil from both physical and chemical perspectives.

[0031] Preferably, the weight ratio of the polysiloxane to nano-silica is (0.5-0.8):(5.8-6.2).

[0032] By adopting the above technical solution, this application further controls the weight ratio of polysiloxane and nano-silica, enabling the two to exert a synergistic effect, thereby further improving the adhesion between the first adhesive layer and the aluminum foil.

[0033] Preferably, the thickness of the printed film is 25-30 μm, the thickness of the first adhesive layer is 5-6 μm, and the thickness of the aluminum foil interlayer is 20-40 μm.

[0034] Secondly, this application provides a method for preparing an easy-tear composite film, which adopts the following technical solution:

[0035] A method for preparing an easy-tear composite film includes the following preparation steps:

[0036] S1: Apply adhesive to the lower surface of the printed film, then attach the aluminum foil intermediate layer to the adhesive, cure, and pull to shape to obtain a composite film semi-finished product. The structure of the composite film semi-finished product is printed film / first adhesive layer / aluminum foil intermediate layer.

[0037] S2. Apply adhesive to the aluminum foil intermediate layer of the composite film semi-finished product obtained in step S1, then laminate the inner heat-sealing film, and then wind and cure it. Then, use a laser method to break the composite film to form dense mechanical holes or easy-tear lines to obtain an easy-tear composite film. The structure of the easy-tear composite film is: printed film / first adhesive layer / aluminum foil intermediate layer / second adhesive layer / inner heat-sealing film.

[0038] By adopting the above technical solution, the preparation method of this application is simple, easy to operate, and suitable for large-scale industrial production.

[0039] In summary, this application has the following beneficial effects:

[0040] 1. The modified polyurethane resin, hyperbranched polymer and phosphate methacrylate in this application can synergistically improve the adhesion, mechanical properties, impact resistance and stability of the first adhesive layer, and, in conjunction with the coupling agent, further improve the adhesion of the first adhesive layer.

[0041] 2. This application introduces organosilicon into polyurethane resin, which can improve the hydrophobicity, stability and flexibility of the first adhesive layer. On the one hand, the hydrophobic properties of organosilicon groups make it difficult for moisture to penetrate between the printed film and the first adhesive layer, thereby improving the moisture resistance and stability of the composite film. On the other hand, it can also improve the flexibility of the first adhesive layer and improve the impact resistance of the first adhesive layer.

[0042] 3. This application uses the above-mentioned polycondensation reaction and amine end-capping agent to obtain hyperbranched polymer. This hyperbranched polymer contains a large number of end groups, has good compatibility with the system, and has high reactivity, which is beneficial to improving the crosslinking of the resin system and enhancing the stability and impact resistance of the first adhesive layer. Detailed Implementation

[0043] Raw material source:

[0044] The polyester polyol is from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd., product number VZ-600355557433;

[0045] Isophore diisocyanate is from Shanghai Liming Chemical Co., Ltd., model number 30155;

[0046] Triethylenediamine is from Shanghai Xiangu Chemical Co., Ltd., model number 546757;

[0047] N-Methyldiethanolamine is from Guangzhou Changhong Chemical Technology Co., Ltd., model number MDEA;

[0048] N,N-Dimethylformamide is from Shandong Gaotai Chemical Technology Co., Ltd., product number 52361;

[0049] Phthalic anhydride is from Shandong Zhijia Chemical Technology Co., Ltd., model number ZJ-005;

[0050] Pentaerythritol is from Guangzhou Jiangshun Technology Co., Ltd., product number HS0974-100;

[0051] Diethylenetriamine was sourced from Jinan Haokun Chemical Co., Ltd., product number H22052;

[0052] The polysiloxane is 3-aminopropyltriethoxysilane;

[0053] The curing agent is from Guangzhou Yele New Materials Co., Ltd., model YL-GB9200;

[0054] Phosphate methacrylate is from Zhongshan Yuanda New Materials Co., Ltd., model number 001;

[0055] The second adhesive layer is formed by curing polyurethane adhesive, which was purchased from Beijing Gaomeng New Materials Co., Ltd., and the model is YH3166.

[0056] The inner heat-sealing film is a polyethylene film;

[0057] MA-5232 silicone oil is from Jining Huakai Resin Co., Ltd.

[0058] The hyperbranched polyester is from Guangzhou Wengjiang Chemical Reagent Co., Ltd., grade 303.

[0059] The present application will be further described in detail below with reference to preparation examples and embodiments.

[0060] Preparation Example

[0061] Preparation of modified polyurethane resin

[0062] Preparation Example 1

[0063] Preparation Example 1.1

[0064] The preparation of modified polyurethane resin includes the following steps:

[0065] S1: Place 25kg of polyester polyol, 21kg of isophor diisocyanate, 2kg of triethylenediamine and 13kg of MA-5232 silicone oil in a reactor and heat to 90℃. React for 2 hours. After the reaction is complete, cool to room temperature to obtain the prepolymer material.

[0066] S2: Mix the prepolymer material from step S1 with 5 kg of N-methyldiethanolamine, heat to 65°C, react for 2 h, cool to 30°C, add glacial acetic acid to neutralize to pH 5, then add 40 kg of acetone to dilute, and remove the acetone solvent under vacuum to obtain the modified polyurethane resin.

[0067] Preparation Example 1.2

[0068] The preparation of modified polyurethane resin includes the following steps:

[0069] S1: Place 30 kg of polyester polyol, 22 kg of isophor diisocyanate, 2.5 kg of triethylenediamine and 14 kg of MA-5232 silicone oil in a reactor and heat to 100°C. React for 2.5 h. After the reaction is complete, cool to room temperature to obtain the prepolymer material.

[0070] S2: Mix the prepolymer material from step S1 with 6 kg of N-methyldiethanolamine, heat to 67°C, react for 2.2 h, cool to 33°C, add glacial acetic acid to neutralize to pH 5.5, then add 45 kg of acetone to dilute, and remove the acetone solvent under vacuum to obtain the modified polyurethane resin.

[0071] Preparation Example 1.3

[0072] The preparation of modified polyurethane resin includes the following steps:

[0073] S1: Place 35kg of polyester polyol, 24kg of isophor diisocyanate, 3kg of triethylenediamine and 15kg of MA-5232 silicone oil in a reactor and heat to 120℃. React for 3 hours. After the reaction is complete, cool to room temperature to obtain the prepolymer material.

[0074] S2: Mix the prepolymer material from step S1 with 7 kg of N-methyldiethanolamine, heat to 70°C, react for 2.5 h, cool to 35°C, add glacial acetic acid to neutralize to pH 6, then add 50 kg of acetone to dilute, and remove the acetone solvent under vacuum to obtain the modified polyurethane resin.

[0075] Preparation Example 1.4

[0076] The difference between Preparation Example 1.4 and Preparation Example 1.2 is that MA-5232 silicone oil was replaced with an equal weight of polydimethylsiloxane, while the other steps were the same as in Preparation Example 1.2.

[0077] Preparation of hyperbranched polymers

[0078] Preparation Example 2

[0079] Preparation Example 2.1

[0080] The preparation of hyperbranched polymers includes the following steps:

[0081] 20 kg of N,N-dimethylformamide, 1.5 kg of phthalic anhydride and 1.4 kg of pentaerythritol were mixed and heated to 120 °C for 4 h of polymerization. Then 3 kg of diethylenetriamine was added and the mixture was reacted at 110 °C for 7 h to obtain the hyperbranched polymer.

[0082] Preparation Example 2.2

[0083] 25 kg of N,N-dimethylformamide, 1.8 kg of phthalic anhydride and 1.5 kg of pentaerythritol were mixed and heated to 122 °C for 6 h of polymerization. Then 10 kg of diethylenetriamine was added and the mixture was reacted at 115 °C for 7.5 h to obtain the hyperbranched polymer.

[0084] Preparation Example 2.3

[0085] 30 kg of N,N-dimethylformamide, 2 kg of phthalic anhydride and 1.6 kg of pentaerythritol were mixed and heated to 125 °C for 8 h of polymerization. Then 15 kg of diethylenetriamine was added and the mixture was reacted at 120 °C for 8 h to obtain the hyperbranched polymer.

[0086] Pretreatment and modification of aluminum foil interlayer

[0087] Preparation Example 3

[0088] Preparation Example 3.1

[0089] The pretreatment and modification of the aluminum foil interlayer includes the following steps:

[0090] S1: Aluminum foil is soaked in a 6wt% sodium hydroxide solution for 5 minutes and then removed and dried;

[0091] S2: The dried aluminum foil is subjected to sanding treatment, wherein the pressure of the sanding roller is 0.2 MPa and the traction speed is 100 m / min, so that micropores are formed on the surface of the aluminum foil to obtain the pre-treated aluminum foil intermediate layer;

[0092] S3: Mix 0.5 kg of polysiloxane, 5 kg of nano-silica and 70 kg of water to form a modification solution. Immerse the pretreated aluminum foil intermediate layer in the modification solution, take it out and dry it to obtain the modified aluminum foil intermediate layer.

[0093] Preparation Example 3.2

[0094] The pretreatment and modification of the aluminum foil interlayer includes the following steps:

[0095] S1: Aluminum foil is soaked in a 7wt% sodium hydroxide solution for 10 minutes and then removed and dried;

[0096] S2: The dried aluminum foil is subjected to sanding treatment, wherein the pressure of the sanding roller is 0.3 MPa and the traction speed is 110 m / min, so that micropores are formed on the surface of the aluminum foil, and the pre-treated aluminum foil intermediate layer is obtained.

[0097] S3: Mix 0.7 kg of polysiloxane, 6 kg of nano-silica and 75 kg of water to form a modification solution. Immerse the pretreated aluminum foil intermediate layer in the modification solution, take it out and dry it to obtain the modified aluminum foil intermediate layer.

[0098] Preparation Example 3.3

[0099] The pretreatment and modification of the aluminum foil interlayer includes the following steps:

[0100] S1: Aluminum foil is soaked in an 8 wt% sodium hydroxide solution for 15 minutes and then removed and dried;

[0101] S2: The dried aluminum foil is subjected to sanding treatment, wherein the pressure of the sanding roller is 0.4 MPa and the traction speed is 120 m / min, so that micropores are formed on the surface of the aluminum foil to obtain the pre-treated aluminum foil intermediate layer.

[0102] S3: Mix 1 kg of polysiloxane, 7 kg of nano-silica and 80 kg of water to form a modification solution. Immerse the pretreated aluminum foil intermediate layer in the modification solution, take it out, and dry it to obtain the modified aluminum foil intermediate layer.

[0103] Preparation Example 3.4

[0104] The difference between Preparation Example 3.4 and Preparation Example 3.1 is that the intermediate layer of the pretreated aluminum foil was not modified.

[0105] Example

[0106] Example 1

[0107] The preparation method of the easy-tear composite film includes the following steps:

[0108] S1: Apply adhesive to the lower surface of the printed film, then attach the aluminum foil intermediate layer to the adhesive, cure, and pull to shape to obtain a composite film semi-finished product. The structure of the composite film semi-finished product is printed film / first adhesive layer / aluminum foil intermediate layer.

[0109] S2. Apply adhesive to the aluminum foil intermediate layer of the composite film semi-finished product obtained in step S1, then laminate the inner heat-sealing film, and then wind and cure it. Then, use laser method to destroy the composite film to form dense mechanical holes or easy-tear lines to obtain an easy-tear composite film. The structure of the easy-tear composite film is: printed film / first adhesive layer / aluminum foil intermediate layer / second adhesive layer / inner heat-sealing film.

[0110] The printing film is a polyethylene terephthalate film.

[0111] The first adhesive layer comprises the following raw materials: 75 kg of modified polyurethane resin (from Preparation Example 1.1), 3 kg of hyperbranched polymer (from Preparation Example 2.1), 2 kg of curing agent, 70 kg of ethyl acetate and 0.5 kg of phosphate methacrylate;

[0112] The polyethylene terephthalate film has a thickness of 25 μm, the first adhesive layer has a thickness of 5 μm, the aluminum foil interlayer has a thickness of 20 μm, the second adhesive layer has a thickness of 5 μm, and the inner heat-sealing film has a thickness of 30 μm.

[0113] Example 2

[0114] The preparation method of the easy-tear composite film includes the following steps:

[0115] S1: Apply adhesive to the lower surface of the printed film, then attach the aluminum foil intermediate layer to the adhesive, cure, and pull to shape to obtain a composite film semi-finished product. The structure of the composite film semi-finished product is printed film / first adhesive layer / aluminum foil intermediate layer.

[0116] S2. Apply adhesive to the aluminum foil intermediate layer of the composite film semi-finished product obtained in step S1, then laminate the inner heat-sealing film, and then wind and cure it. Then, use laser method to destroy the composite film to form dense mechanical holes or easy-tear lines to obtain an easy-tear composite film. The structure of the easy-tear composite film is: printed film / first adhesive layer / aluminum foil intermediate layer / second adhesive layer / inner heat-sealing film.

[0117] The printing film is a polyethylene terephthalate film.

[0118] The first adhesive layer comprises the following raw materials: 77 kg of modified polyurethane resin (from Preparation Example 1.1), 3.5 kg of hyperbranched polymer (from Preparation Example 2.1), 3 kg of curing agent, 75 kg of ethyl acetate and 0.6 kg of phosphate methacrylate;

[0119] The polyethylene terephthalate film has a thickness of 27 μm, the first adhesive layer has a thickness of 5 μm, the aluminum foil interlayer has a thickness of 30 μm, the second adhesive layer has a thickness of 5 μm, and the inner heat-sealing film has a thickness of 30 μm.

[0120] Example 3

[0121] The preparation method of the easy-tear composite film includes the following steps:

[0122] S1: Apply adhesive to the lower surface of the printed film, then attach the aluminum foil intermediate layer to the adhesive, cure, and pull to shape to obtain a composite film semi-finished product. The structure of the composite film semi-finished product is printed film / first adhesive layer / aluminum foil intermediate layer.

[0123] S2. Apply adhesive to the aluminum foil intermediate layer of the composite film semi-finished product obtained in step S1, then laminate the inner heat-sealing film, and then wind and cure it. Then, use laser method to destroy the composite film to form dense mechanical holes or easy-tear lines to obtain an easy-tear composite film. The structure of the easy-tear composite film is: printed film / first adhesive layer / aluminum foil intermediate layer / second adhesive layer / inner heat-sealing film.

[0124] The printing film is a polyethylene terephthalate film.

[0125] The first adhesive layer comprises the following raw materials: 80 kg of modified polyurethane resin (from Preparation Example 1.1), 4 kg of hyperbranched polymer (from Preparation Example 2.1), 4 kg of curing agent, 80 kg of ethyl acetate and 0.8 kg of phosphate methacrylate;

[0126] The polyethylene terephthalate film has a thickness of 30 μm, the first adhesive layer has a thickness of 6 μm, the aluminum foil interlayer has a thickness of 40 μm, the second adhesive layer has a thickness of 5 μm, and the inner heat-sealing film has a thickness of 30 μm.

[0127] Examples 4-6

[0128] The difference between Examples 4-6 and Example 3 is that the modified polyurethane resins are derived from Preparation Examples 1.2-1.4 respectively, while the remaining steps are the same as in Example 3.

[0129] Examples 7-8

[0130] The difference between Examples 7-8 and Example 4 is that the hyperbranched polymers are derived from Preparation Example 2.2 and Preparation Example 2.3, respectively, while the remaining steps are the same as in Example 4.

[0131] Example 9

[0132] The difference between Example 9 and Example 7 is that the hyperbranched polymer in this application is replaced with a commercially available hyperbranched polyester, while the other steps are the same as in Example 7.

[0133] Examples 10-14

[0134] The difference between Examples 10-14 and Example 7 lies in the weight and weight ratio of the modified polyurethane resin, hyperbranched polymer, and phosphate methacrylate. Specific data are shown in the table below:

[0135] Table 1. Weights of modified polyurethane resin, hyperbranched polymer, and phosphate methacrylate in Examples 10-14

[0136] Modified polyurethane resin / kg hyperbranched polymers / kg Phosphate methacrylate / kg Example 10 77 3.5 0.6 Example 11 78 3.2 0.7 Example 12 77.5 3.3 0.65 Example 13 76 3.6 0.5 Example 14 79 3.1 0.8

[0137] Examples 15-18

[0138] The difference between Examples 15-18 and Example 11 is that the aluminum foil interlayer is pretreated and modified. The aluminum foil interlayer is derived from Preparation Examples 3.1-3.4 respectively. The remaining steps are the same as in Example 11.

[0139] Example 19

[0140] The difference between Example 19 and Example 17 is that the polysiloxane in the modifier is replaced with an equal weight of stearic acid, while the rest of the steps are the same as in Example 17.

[0141] Example 20

[0142] The difference between Example 20 and Example 17 is that the nano-silica of the modifier is replaced with an equal weight of nano-titanium dioxide, while the rest of the steps are the same as in Example 17.

[0143] Examples 21-25

[0144] The difference between Examples 21-25 and Example 17 lies in the mass and mass ratio of polysiloxane and nano-silica in the modified solution. Specific data are shown in the table below:

[0145] Table 2. Mass of polysiloxane and nano-silica in Examples 21-25

[0146]

[0147]

[0148] Comparative Example

[0149] Comparative Example 1

[0150] The difference between Comparative Example 1 and Example 1 is that no hyperbranched polymer was added, while the rest of the steps were the same as in Example 1.

[0151] Comparative Example 2

[0152] The difference between Comparative Example 2 and Example 1 is that the modified polyurethane resin is an epoxy resin modified polyurethane resin. For the specific modification steps, please refer to Example 1 in the invention patent with publication number CN115160529B.

[0153] Comparative Example 3

[0154] The difference between Comparative Example 3 and Example 1 is that no phosphate methacrylate was added, while the rest of the steps were the same as in Example 1.

[0155] Comparative Example 4

[0156] The difference between Comparative Example 4 and Example 1 is that phosphate methacrylate is replaced with an equal weight of alkyl phosphate acrylate, while the rest of the steps are the same as in Example 1.

[0157] Performance testing

[0158] Detection methods

[0159] Peel strength test: The peel strength of the printed film to the aluminum foil interlayer in the easy-tear composite film obtained in the above examples and comparative examples was tested, and the peel strength was carried out in accordance with the provisions of GB8808-1988 "Peel Test Method for Flexible Composite Plastic Materials".

[0160] The limit of the punching depth of the aluminum-plastic film: The easy-tear composite film obtained in the above examples and comparative examples was punched using a mold of model 104050 with a radius of 1.5° and a pressure of 0.6MPa. The appearance of the samples was checked and the punching depth was measured with a measuring tool with an accuracy of 0.01mm.

[0161] Aluminum-plastic film moisture resistance: The easy-tear composite films obtained in the above examples and comparative examples were placed in water, and after two days, the presence of bubbling / delamination was observed in the middle layer between the printed film and the aluminum foil. Specific test results are shown in the table below:

[0162] Table 3. Comprehensive performance data of the easy-tear composite films prepared in Examples 1-25 and Comparative Examples 1-4

[0163]

[0164]

[0165] Based on Examples 1 and Comparative Examples 1-4, and the data in Table 3, it can be seen that hyperbranched polymers can improve the impact resistance of easy-tear composite films and also improve the adhesion between the printed film and the aluminum foil interlayer. Organosilicon-modified polyurethane resin can effectively improve the moisture resistance and impact resistance of the composite film. Phosphate methacrylate can effectively improve the adhesion and stability between the printed film and the aluminum foil interlayer. Compared with alkyl phosphate acrylate, phosphate methacrylate incorporated into the polyurethane system to form the first adhesive layer has certain advantages. This may be because phosphate methacrylate makes the hyperbranched polymer and the modified polyurethane resin more miscible, which promotes the stability of the resin system. The synergistic effect of the modified polyurethane resin, hyperbranched polymer, and phosphate methacrylate improves the adhesion, impact resistance, and stability of the first adhesive layer.

[0166] Based on the data from Examples 1-3 and Table 3, it can be seen that the easy-tear composite film prepared in Example 3 has better overall performance.

[0167] Based on the data from Examples 3-6, it can be seen that the modified polyurethane resin prepared in Example 1.2 has better bonding and impact resistance properties. In addition, compared with ordinary silicone oil modified polyurethane resin, MA-5232 silicone oil modified polyurethane resin has better overall performance. This may be because MA-5232 silicone oil has good compatibility with the polyurethane system and high reactivity, which can further enhance the stability and impact resistance of the first adhesive layer.

[0168] Based on the data from Examples 4, 7-9, and Table 3, it can be seen that the hyperbranched polymer prepared in Preparation Example 2.2 has superior performance when incorporated into the resin system to form the first adhesive layer. Furthermore, the hyperbranched polymer prepared in this application has higher reactivity and better compatibility with the resin system, thus further enhancing the bonding performance and impact resistance of the first adhesive layer.

[0169] Based on the data from Examples 7, 10-14 and Table 3, it can be seen that when the weight ratio of modified polyurethane resin, hyperbranched polymer and phosphate methacrylate is (77-78):(3.2-3.5):(0.6-0.7), the three components can further exert a synergistic effect, thereby further improving the bonding performance and impact resistance of the first adhesive layer.

[0170] Based on the data from Examples 11, 15-18 and Table 3, it can be seen that the adhesion between the modified aluminum foil and the printed film is significantly improved, and the adhesion between the modified aluminum foil intermediate layer in Example 3.3 and the printed film is better.

[0171] Based on the data from Examples 17, 19-20 and Table 3, it can be seen that polysiloxane and nano-titanium dioxide can synergistically improve the adhesion between the first adhesive layer and the aluminum foil.

[0172] Based on the data from Examples 17, 21-25 and Table 3, it can be seen that when the weight ratio of polysiloxane to nano-silica is in the range of (0.5-0.8):(5.8-6.2), polysiloxane and nano-titanium dioxide can further synergistically improve the adhesion between the first adhesive layer and the aluminum foil.

[0173] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. An easy-tear composite film, characterized in that: From top to bottom, it includes a printed film, a first adhesive layer, an aluminum foil intermediate layer, a second adhesive layer, and an inner heat-sealed polyethylene film; The printed film is a polyethylene terephthalate film. The first adhesive layer comprises the following raw materials in parts by weight: 75-80 parts modified polyurethane resin, 3-4 parts hyperbranched polymer, 2-4 parts curing agent, 70-80 parts ethyl acetate and 0.5-0.8 parts phosphate methacrylate; The preparation of the modified polyurethane resin includes the following steps: S1: Place 25-35 parts by weight of polyester polyol, 21-24 parts by weight of isophorone diisocyanate, 2-3 parts by weight of triethylenediamine and 13-15 parts by weight of silicone oil in a reactor and heat to 90-120°C. React for 2-3 hours. After the reaction is complete, cool to room temperature to obtain the prepolymer material. S2: Mix the prepolymer material from step S1 with 5-7 parts by weight of N-methyldiethanolamine, heat to 65-70°C, react for 2-2.5 hours, cool to 30-35°C, add glacial acetic acid to neutralize to pH 5-6, then add 40-50 parts by weight of acetone to dilute, and remove the acetone solvent under vacuum to obtain the modified polyurethane resin. The hyperbranched polymer comprises the following preparation steps: Mix 20-30 parts by weight of N,N-dimethylformamide, 1.5-2 parts by weight of phthalic anhydride and 1.4-1.6 parts by weight of pentaerythritol, heat to 120-125℃, and polymerize for 4-8 hours. Then add 3-15 parts by weight of diethylenetriamine and react at 110-120℃ for 7-8 hours to obtain a hyperbranched polymer.

2. The easy-tear composite film according to claim 1, characterized in that: The silicone oil is MA-5232 silicone oil.

3. The easy-tear composite film according to claim 1, characterized in that: The weight ratio of the modified polyurethane resin, hyperbranched polymer, and phosphate methacrylate is (77-78):(3.2-3.5):(0.6-0.7).

4. The easy-tear composite film according to claim 1, characterized in that: The aluminum foil interlayer also undergoes pretreatment, which includes the following steps: S1: Aluminum foil is soaked in a 6wt% to 8wt% sodium hydroxide solution for 5 to 15 minutes and then removed and dried; S2: The dried aluminum foil is subjected to sanding treatment, wherein the pressure of the sanding roller is 0.2-0.4 MPa and the traction speed is 100-120 m / min, so that micropores are formed on the surface of the aluminum foil, and the pre-treated aluminum foil intermediate layer is obtained.

5. The easy-tear composite film according to claim 4, characterized in that: The pretreated aluminum foil is further modified. The modification process includes the following steps: mixing 0.5-1 parts by weight of polysiloxane, 5-7 parts by weight of nano-silica and 70-80 parts by weight of water to form a modification solution; immersing the pretreated aluminum foil in the modification solution; taking it out; and drying it to obtain the modified aluminum foil intermediate layer.

6. The easy-tear composite film according to claim 5, characterized in that: The weight ratio of the polysiloxane to nano-silica is (0.5-0.8):(5.8-6.2).

7. The easy-tear composite film according to claim 1, characterized in that: The thickness of the printed film is 25-30 μm, the thickness of the first adhesive layer is 5-6 μm, and the thickness of the aluminum foil intermediate layer is 20-40 μm.

8. A method for preparing the easy-tear composite film according to any one of claims 1-7, characterized in that: The preparation steps include the following: S1: Apply adhesive to the lower surface of the printed film, then attach the aluminum foil intermediate layer to the adhesive, cure, and pull to shape to obtain a composite film semi-finished product. The structure of the composite film semi-finished product is printed film / first adhesive layer / aluminum foil intermediate layer. S2: Apply adhesive to the aluminum foil intermediate layer of the composite film semi-finished product obtained in step S1, then laminate the inner heat-sealed polyethylene film, and then wind and cure it. Then, use a laser method to break the composite film to form dense mechanical holes or easy-tear lines to obtain an easy-tear composite film. The structure of the easy-tear composite film is: printed film / first adhesive layer / aluminum foil intermediate layer / second adhesive layer / inner heat-sealed polyethylene film.

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