Milk-staining-free easy-to-uncover composite cover film and manufacturing method thereof

Abstract

The manufacturing method of the non-staining easy-to-uncover composite cover film comprises the following steps: premixing the following raw materials in parts by weight: 30-90 parts of matrix resin, 10-50 parts of inorganic particles, 1-15 parts of a dispersing agent and 0.5-5 parts of a slipping agent, and granulating to prepare easy-to-uncover master batch particles; melting and co-extruding the easy-to-uncover master batch particles and PE heat-sealing particles to prepare a heat-sealing easy-to-uncover layer; the inorganic particles are one or a mixture of two of silica and talcum powder. Dissolving an organic silicon anti-sticking agent in a solvent to prepare anti-sticking coating liquid, wherein the organic silicon anti-sticking agent is organic silicon resin containing one or more active groups of amino, epoxy group, methoxyl and ethyoxyl; the anti-sticking coating liquid is coated on one surface, containing the inorganic particle components, of the heat-sealing easy-to-tear layer, and then solvent drying is performed to obtain the anti-sticking coating. The cover film prepared by the method has a non-milk-staining function, the non-milk-staining coating has a better anti-scraping effect, the problem of coating falling is avoided, and after the cover film is subjected to heat sealing with cups / bottles / trays made of various materials, the cover film also has an easy-to-uncover effect.

Description

Technical Field

[0001] The present invention relates to a composite film, and more particularly to a non-milky-sticking and easily-peelable composite cover film and a manufacturing method thereof. Background Art

[0002] Among dairy products, yogurt products are rich in nutrition and diverse in taste, and are widely accepted and loved by people.

[0003] The packaging method of "yogurt cup + easily-peelable cover film" is one of the packaging methods for commercially circulated yogurt in large quantities at present. However, viscous yogurt is likely to adhere to the cover film, causing difficulties in consumption and waste. At present, there are also methods of coating a primer and a hydrophobic layer on the inner surface of the cover film by coating to achieve the effect of non-milky-sticking, but there are problems such as poor coating adhesion and easy peeling. Summary of the Invention

[0004] In view of the above deficiencies of the prior art, the present application provides a non-milky-sticking and easily-peelable composite cover film and a manufacturing method thereof. The obtained non-milky-sticking and easily-peelable composite cover film has the function of non-milky-sticking, its non-milky-sticking coating has better scratch resistance and will not have the problem of coating peeling. After heat-sealing with cups / bottles / trays of various materials, it also has the effect of being easily peeled.

[0005] A manufacturing method of a non-milky-sticking and easily-peelable composite cover film is disclosed, which includes the following steps:

[0006] S1. Preparation of the heat-sealing and easily-peelable layer:

[0007] Raw materials containing the following parts by weight: 30-90 parts of matrix resin, 10-50 parts of inorganic particles, 1-15 parts of dispersant, and 0.5-5 parts of slip agent are pre-mixed and granulated to form easily-peelable masterbatch particles. Specifically, the masterbatch is made by the method of melting and mixing and extruding granulation using a twin-screw extruder; the easily-peelable masterbatch particles and PE heat-sealing particles are melt co-extruded in an extruder to obtain the heat-sealing and easily-peelable layer.

[0008] The inorganic particles are one or a mixture of two of silica and talcum powder. The median diameter of the inorganic particles is 2-10 μm. The inorganic particles have the following three functions: one is to act as a slip agent in the formula, the second is to be able to adjust the cohesive force in the film layer to thus adjust the easily-peeling effect, and the third is to make the surface of the cover film facing the inside of the cup uneven, increasing the contact angle;

[0009] S2. Preparation of the anti-sticking coating:

[0010] Dissolve the silicone anti-sticking agent in a solvent to prepare an anti-sticking coating solution. The silicone anti-sticking agent is a silicone resin containing one or more active groups such as amino group, epoxy group, methoxy group, and ethoxy group. The solvent is one or more of water, alcohol organic solvents (ethanol, isopropanol, propanol, butanol), and ester organic solvents (ethyl acetate, propyl acetate, butyl acetate).

[0011] Coat the anti-sticking coating solution on one side of the heat-sealable and easy-to-peel layer containing inorganic particle components, and finally dry the solvent in an oven to obtain an anti-sticking coating. During this solvent drying process, due to the presence of groups such as hydroxyl group and carboxyl group in the inorganic particle components of the heat-sealable and easy-to-peel layer, the active groups of the silicone anti-sticking agent can react with them, thereby riveting to the surface of the heat-sealable and easy-to-peel layer, making the non-sticking milk effect more lasting, the anti-scratch effect better, and there will be no problem of coating peeling off.

[0012] Preferably, in step S1, the matrix resin is a polyethylene-based matrix resin or a polypropylene-based matrix resin.

[0013] The polyethylene-based matrix resin is one of polyethylene, ethylene-acrylate copolymer, and ethylene-vinyl acetate copolymer.

[0014] The polypropylene-based matrix resin is polypropylene, maleic acid-modified polypropylene, or chlorinated polypropylene.

[0015] Further, when the matrix resin is a polypropylene-based matrix resin, step S1 further includes resin-type adhesive particles. The easy-to-peel masterbatch particles, resin-type adhesive particles, and PE heat-sealing particles are melt co-extruded in an extruder to obtain a heat-sealable and easy-to-peel layer. After the resin-type adhesive particles are melt-extruded, they form an intermediate adhesive film layer in the heat-sealable and easy-to-peel layer. The function of the resin-type adhesive particles: Since the polypropylene-based matrix resin and the PE heat-sealing particles have poor compatibility, the addition of the resin-type adhesive particles can make the obtained heat-sealable and easy-to-peel layer more stable and not easy to delaminate.

[0016] Preferably, the resin-type adhesive particles are ethylene-acrylate copolymer or maleic anhydride grafted polypropylene.

[0017] Preferably, in step S1, the dispersant is one of polyethylene wax, oleic acid amide, stearate, titanate coupling agent, and polyethylene-maleic acid copolymer. The above dispersants are amphiphilic small molecules or polymers, containing both polar and non-polar groups, having hydrophilic and lipophilic properties. Using them to disperse inorganic particles can enhance the interaction between the inorganic particles and the matrix resin, making the inorganic particles not easy to fall off from the matrix resin.

[0018] Preferably, in step S1, the slip agent is erucic acid amide, which can adjust the surface slip performance.

[0019] Preferably, in step S2, the coating method is roll coating or spraying, and roll coating is preferably used. The coating amount is 0.1-1.0 gsm.

[0020] A non-milky and easily peelable composite lid film prepared by the above method, which includes a heat-sealable and easily peelable layer and an anti-sticking coating. The anti-sticking coating is coated and compounded on one side of the heat-sealable and easily peelable layer containing inorganic particle components according to the method.

[0021] Furthermore, the non-milky and easily peelable composite lid film further includes a printing layer and a barrier layer. The barrier layer is compounded on the other side of the heat-sealable and easily peelable layer through a polyurethane adhesive. The printing layer is compounded on the surface of the barrier layer through a polyurethane adhesive. The barrier layer is AL or MPET, and the printing layer is a PET or BOPP or nylon film or paper printed with patterns.

[0022] Through the above technical solutions, the present invention at least includes the following beneficial effects:

[0023] The non-milky and easily peelable composite lid film described in the present application, through the preparation of the heat-sealable and easily peelable layer with specific formula components and the coating of the anti-sticking coating solution, enables the active groups of the silicone anti-sticking agent in the anti-sticking coating solution to react with the inorganic particle components containing hydroxyl, carboxyl and other groups in the heat-sealable and easily peelable layer during the solvent drying process, so as to rivet to the surface of the heat-sealable and easily peelable layer, making the non-milky effect more lasting, the anti-scratch effect better, and there will be no problem of coating peeling off. That is, the technical solution of the present invention can effectively solve the problem that the adhesion of the traditional non-milky coating is poor and easy to fall off. At the same time, the non-milky and easily peelable composite lid film of the present application can also match cups / bottles / trays of various materials. The heat-sealable objects include materials such as PE, PET, PP and PS. The application range is wide, and it has an easily peelable effect after heat-sealing, and the consumer experience is good. Specific Embodiments

[0024] The technical solutions of the invention will be clearly and completely described below through embodiments, and the application of the present invention is not limited to the cited embodiments.

[0025] Example 1

[0026] A manufacturing method of a non-milky and easily peelable composite lid film, which includes the following steps:

[0027] S1. Preparation of the heat-sealable and easily peelable layer:

[0028] It will contain the following raw materials in parts by weight: 60 parts of matrix resin, 30 parts of inorganic particles, 8 parts of dispersant and 3 parts of slip agent. After premixing, it is granulated to make an easy-to-peel masterbatch particle, and specifically, it is made into the masterbatch by the method of melt mixing and extrusion granulation using a twin-screw extruder; the easy-to-peel masterbatch particle and PE heat-sealing particles (containing 40% LDPE and 60% LLDPE) are melt co-extruded in an extruder to obtain a heat-sealing and easy-to-peel layer, and the total thickness of the heat-sealing and easy-to-peel layer is 50 μm, among which the thickness of the film layer extruded from the easy-to-peel masterbatch particle is 10 μm;

[0029] The inorganic particles are talc powder, and the median diameter of the inorganic particles is 5 μm. The inorganic particles have the following three functions: one is as a slip agent in the formula, the second is to be able to adjust the cohesive force in the film layer so as to adjust the easy-to-peel effect, and the third is to make the surface of the cover film concave and convex towards the inside of the cup, increasing the contact angle;

[0030] The matrix resin is polyethylene, and the dispersant is polyethylene wax. This amphiphilic polymer dispersant contains both polar and non-polar groups and has hydrophilic and lipophilic properties. Using it to disperse inorganic particles can enhance the interaction between the inorganic particles and the matrix resin, making the inorganic particles not easily fall off from the matrix resin; the slip agent is erucamide, which can adjust the surface slip performance.

[0031] S2. Preparation of the anti-sticking coating:

[0032] Dissolve the silicone anti-sticking agent in a solvent to make a 10wt% anti-sticking coating solution. The silicone anti-sticking agent is a silane containing ethoxy groups, and the solvent is a 1:1 mixture of alcohol and water;

[0033] Coat the anti-sticking coating solution on the side of the heat-sealing and easy-to-peel layer containing inorganic particle components. Specifically, it is coated by a gravure roll coating method on a coater, and the coating amount is 0.5 gsm. Finally, the solvent is dried in an oven to obtain the anti-sticking coating; during this solvent drying process, because the inorganic particle components in the heat-sealing and easy-to-peel layer contain groups such as hydroxyl and carboxyl groups, the active groups of the silicone anti-sticking agent can react with them, so as to rivet to the surface of the heat-sealing and easy-to-peel layer, making the non-milking effect more lasting, the anti-scratch effect better, and no coating peeling problem will occur.

[0034] S3. Preparation of the printing layer and the barrier layer: The AL aluminum foil barrier layer is laminated on the other side of the heat-sealing and easy-to-peel layer through a polyurethane adhesive, the printing layer is laminated on the surface of the barrier layer through a polyurethane adhesive, the thickness of the barrier layer is 7 μm, the printing layer is PET printed with patterns, with a thickness of 12 μm, and the thickness of both polyurethane adhesive layers is 3 μm.

[0035] Example 2

[0036] A manufacturing method of a non-milking and easy-to-peel composite cover film, which includes the following steps:

[0037] S1. Preparation of heat-sealable and peelable layer:

[0038] Raw materials in the following parts by weight are pre-mixed and pelletized to form a peelable masterbatch particle: 75 parts of matrix resin, 40 parts of inorganic particles, 15 parts of dispersant, and 4 parts of slip agent. Specifically, the masterbatch is prepared by melt mixing and extrusion granulation using a twin-screw extruder; the peelable masterbatch particle, resin-type adhesive particle, and PE heat-sealing particle (containing 40% LDPE and 60% LLDPE) are melt co-extruded in an extruder to obtain the heat-sealable and peelable layer. The resin-type adhesive particle forms an intermediate adhesive film layer in the heat-sealable and peelable layer after extrusion; the total thickness of the heat-sealable and peelable layer is 40 μm, among which the thickness of the intermediate adhesive film layer is 4 μm, and the thickness of the film layer extruded from the peelable masterbatch particle is 8 μm.

[0039] The inorganic particle is talcum powder, and the median diameter of the inorganic particle is 6 μm. This inorganic particle has the following three functions: first, it acts as a slip agent in the formulation; second, it can adjust the cohesive force within the film layer to regulate the peelable effect; third, it makes the surface of the lid film concave and convex towards the inside of the cup, increasing the contact angle.

[0040] The matrix resin is a polypropylene-based matrix resin, specifically maleic acid-modified polypropylene. The resin-type adhesive particle is maleic anhydride-grafted polypropylene. Since the polypropylene-based matrix resin and PE heat-sealing particle have poor compatibility, the addition of this resin-type adhesive particle can make the obtained heat-sealable and peelable layer more stable and less likely to delaminate.

[0041] The dispersant is calcium stearate. This amphiphilic small molecule dispersant contains both polar and non-polar groups, having hydrophilic and lipophilic properties. Using it to disperse inorganic particles can enhance the interaction between inorganic particles and matrix resin, making the inorganic particles not easily fall off from the matrix resin; the slip agent is erucamide, which can adjust the surface slip performance.

[0042] S2. Preparation of anti-sticking coating:

[0043] An organosilicon anti-sticking agent is dissolved in a propanol solvent to form a 10 wt% anti-sticking coating solution. The organosilicon anti-sticking agent is a silane containing methoxy groups.

[0044] The anti-sticking coating solution is coated on the side of the heat-sealable and peelable layer containing inorganic particle components. Specifically, it is coated by a gravure roll coater on a coater, and the coating amount is 0.3 gsm. Finally, the solvent is dried in an oven to obtain the anti-sticking coating; during this solvent drying process, since the inorganic particle components in the heat-sealable and peelable layer contain groups such as hydroxyl and carboxyl groups, the active groups of the organosilicon anti-sticking agent can react with them, thus riveting to the surface of the heat-sealable and peelable layer, making the non-milking effect more lasting, the anti-scratch effect better, and no coating peeling problem will occur.

[0045] S3. Preparation of the printing layer and the barrier layer: The MPET barrier layer is laminated to the other side of the heat-sealable and easily peelable layer through a polyurethane adhesive, the printing layer is laminated to the surface of the barrier layer through a polyurethane adhesive, the thickness of the barrier layer is 12 μm, the printing layer is BOPP printed with patterns, with a thickness of 15 μm, and the thickness of both polyurethane adhesive layers is 3 μm.

[0046] Example 3

[0047] A method for manufacturing a non-sticky milk and easily peelable composite cover film, which comprises the following steps:

[0048] S1. Preparation of the heat-sealable and easily peelable layer:

[0049] Raw materials containing the following parts by weight: 90 parts of matrix resin, 50 parts of inorganic particles, 13 parts of dispersant and 5 parts of slip agent are pre-mixed and granulated to form easily peelable masterbatch particles, specifically by melting, mixing and extruding granulation using a twin-screw extruder to make the masterbatch; the easily peelable masterbatch particles and PE heat-sealing particles (containing 20% LDPE and 80% LLDPE) are melt co-extruded in an extruder to obtain the heat-sealable and easily peelable layer, the total thickness of the heat-sealable and easily peelable layer is 34 μm, and the thickness of the film layer extruded from the easily peelable masterbatch particles is 10 μm.

[0050] The inorganic particles are a 1:1 mixture of silica and talc powder, the median diameter of the talc powder is 8 μm, and the median diameter of the silica is 6 μm. The inorganic particles have the following three functions: one is to act as a slip agent in the formulation, the second is to be able to adjust the cohesive force within the film layer to thereby adjust the easy peeling effect, and the third is to make the surface of the cover film concave and convex towards the inside of the cup, increasing the contact angle;

[0051] The matrix resin is a polyethylene-based matrix resin, specifically an ethylene-acrylate copolymer; the dispersant is oleic acid amide. This amphiphilic dispersant contains both polar and non-polar groups, has hydrophilic and lipophilic properties, and using it to disperse inorganic particles can enhance the interaction between the inorganic particles and the matrix resin, making the inorganic particles not easily fall off from the matrix resin; the slip agent is erucic acid amide, which can adjust the surface slip performance.

[0052] S2. Preparation of the anti-stick coating:

[0053] The organosilicon anti-stick agent is dissolved in an ethyl acetate solvent to make a 10 wt% anti-stick coating solution, and the organosilicon anti-stick agent is a silane containing methoxy groups;

[0054] The anti - sticking coating liquid is coated on the side of the heat - sealable and peelable layer containing inorganic particle components. Specifically, it is coated by a gravure roll on a coater, and the coating amount is 0.1 gsm. Finally, the solvent is dried in an oven to obtain the anti - sticking coating. During this solvent drying process, because the inorganic particle components in the heat - sealable and peelable layer contain groups such as hydroxyl and carboxyl groups, the active groups of the silicone anti - sticking agent can react with them, thus riveting to the surface of the heat - sealable and peelable layer, making the non - milk - sticking effect more durable, the anti - scratch effect better, and there will be no problem of coating peeling off.

[0055] S3. Preparation of the printing layer and the barrier layer: The MPET barrier layer is laminated on the other side of the heat - sealable and peelable layer through a polyurethane adhesive. The printing layer is laminated on the surface of the barrier layer through a polyurethane adhesive. The thickness of the barrier layer is 6 μm, the printing layer is a paper printed with patterns, with a thickness of 40 μm, and the thickness of both polyurethane adhesive layers is 3 μm.

[0056] Example 4

[0057] A method for manufacturing a non - milk - sticking and easily - peelable composite cover film, which includes the following steps:

[0058] S1. Preparation of the heat - sealable and peelable layer:

[0059] Raw materials containing the following weight parts: 45 parts of matrix resin, 20 parts of inorganic particles, 4 parts of dispersant, and 2 parts of slip agent are pre - mixed and granulated to make an easily - peelable masterbatch particle. Specifically, it is made into the masterbatch by the method of melt - mixing and extruding granulation using a twin - screw extruder. The easily - peelable masterbatch particle and PE heat - seal particles (containing 20% LDPE and 80% LLDPE) are melt - co - extruded in an extruder to obtain the heat - sealable and peelable layer. The total thickness of the heat - sealable and peelable layer is 30 μm, and the thickness of the film layer extruded from the easily - peelable masterbatch particle is 10 μm.

[0060] The inorganic particles are a 1:1 mixture of talc powder and silica. The median diameter of the talc powder is 10 μm, and the median diameter of the silica is 2 μm. These inorganic particles have the following three functions: one is to act as a slip agent in the formula, the second is to be able to adjust the internal cohesion of the film layer to adjust the easy - peeling effect, and the third is to make the surface of the cover film facing the inside of the cup concave and convex, increasing the contact angle.

[0061] The matrix resin is a polyethylene - based matrix resin, specifically ethylene - vinyl acetate copolymer. The dispersant is a titanate coupling agent. This amphiphilic dispersant contains both polar and non - polar groups, having hydrophilic and lipophilic properties. Using it to disperse inorganic particles can enhance the interaction between inorganic particles and the matrix resin, making the inorganic particles not easily fall off from the matrix resin. The slip agent is erucamide, which can adjust the surface slip performance.

[0062] S2. Preparation of the anti - sticking coating:

[0063] Dissolve the silicone anti - sticking agent in ethyl acetate solvent to make an 8wt% anti - sticking coating solution. The silicone anti - sticking agent is a silane containing ethoxy and amino groups;

[0064] Coat the anti - sticking coating solution on the side of the heat - sealable and easily - peelable layer containing inorganic particle components. Specifically, use the spraying coating method, and the coating amount is 0.7 gsm. Finally, dry the solvent in an oven to obtain the anti - sticking coating; during this solvent drying process, because the inorganic particle components in the heat - sealable and easily - peelable layer contain groups such as hydroxyl and carboxyl groups, the active groups of the silicone anti - sticking agent can react with them, thus riveting to the surface of the heat - sealable and easily - peelable layer, making the non - milk - sticking effect more durable, the anti - scratching effect better, and there will be no problem of coating peeling off.

[0065] S3. Preparation of the printing layer and the barrier layer: Compound the aluminum foil barrier layer on the other side of the heat - sealable and easily - peelable layer through polyurethane adhesive. The printing layer is compounded on the surface of the barrier layer through polyurethane adhesive. The thickness of the barrier layer is 7μm, the printing layer is PET printed with patterns, with a thickness of 12μm, and the thickness of both polyurethane adhesive layers is 3μm.

[0066] Example 5

[0067] A method for making a non - milk - sticking and easily - peelable composite cover film, which includes the following steps:

[0068] S1. Preparation of the heat - sealable and easily - peelable layer:

[0069] Pre - mix the raw materials containing the following parts by weight: 30 parts of matrix resin, 10 parts of inorganic particles, 1 part of dispersant, and 0.5 part of slip agent, and then granulate to make an easily - peelable masterbatch particle. Specifically, use a twin - screw extruder to melt - mix and extrude granulation to make this masterbatch; melt - co - extrude the easily - peelable masterbatch particles, resin - type adhesive particles, and PE heat - seal particles (containing 20% LDPE and 80% LLDPE) in an extruder to obtain the heat - sealable and easily - peelable layer. The resin - type adhesive particles form an intermediate adhesive film layer in the heat - sealable and easily - peelable layer after extrusion; the total thickness of the heat - sealable and easily - peelable layer is 45μm, among which, the thickness of the intermediate adhesive film layer is 9μm, and the thickness of the film layer extruded from the easily - peelable masterbatch particles is 8μm.

[0070] The inorganic particles are silica, and the median diameter of the inorganic particles is 6μm. These inorganic particles have the following three functions: one is to act as a slip agent in the formula, the second is to be able to adjust the cohesive force within the film layer to thus adjust the easily - peelable effect, and the third is to make the surface of the cover film concave and convex towards the inside of the cup, increasing the contact angle;

[0071] The matrix resin is a polypropylene-based matrix resin, specifically chlorinated polypropylene. The resin-type adhesive particles are ethylene-acrylate copolymer. Since the compatibility between the polypropylene-based matrix resin and the PE heat-sealing particles is poor, the addition of the resin-type adhesive particles can make the prepared heat-sealable and easily peelable layer more stable and less likely to delaminate.

[0072] The dispersant is a polyethylene-maleic acid copolymer. This dispersant is an amphiphilic polymer, containing both polar and non-polar groups, and having hydrophilic and lipophilic properties. Using it to disperse inorganic particles can enhance the interaction between the inorganic particles and the matrix resin, making the inorganic particles not easily fall off from the matrix resin. The slip agent is erucamide, which can adjust the surface slip performance.

[0073] S2. Preparation of the anti-sticking coating:

[0074] Dissolve the silicone anti-sticking agent in butyl acetate solvent to make a 5wt% anti-sticking coating solution. The silicone anti-sticking agent is a silane containing epoxy groups and ethoxy groups.

[0075] Coat the anti-sticking coating solution on the side of the heat-sealable and easily peelable layer containing inorganic particle components. The specific coating method is spraying, and the coating amount is 1.0 gsm. Finally, dry the solvent in an oven to obtain the anti-sticking coating. During this solvent drying process, since the inorganic particle components in the heat-sealable and easily peelable layer contain groups such as hydroxyl groups and carboxyl groups, the active groups of the silicone anti-sticking agent can react with them, thereby riveting to the surface of the heat-sealable and easily peelable layer, making the non-milking effect more lasting, the anti-scratch effect better, and no coating peeling problem will occur.

[0076] S3. Preparation of the printing layer and the barrier layer: Composite the MPET barrier layer on the other side of the heat-sealable and easily peelable layer through a polyurethane adhesive. The printing layer is composite on the surface of the barrier layer through a polyurethane adhesive. The thickness of the barrier layer is 7 μm, the printing layer is a nylon film printed with patterns, with a thickness of 20 μm, and the thickness of both polyurethane adhesive layers is 3 μm.

[0077] Example 6

[0078] A method for making a non-milking and easily peelable composite cover film, which includes the following steps:

[0079] S1. Preparation of the heat-sealable and easily peelable layer:

[0080] The raw materials in the following parts by weight are included: 70 parts of matrix resin, 45 parts of inorganic particles, 14 parts of dispersant and 3 parts of slip agent. After pre-mixing, they are granulated to make the easy-peeling masterbatch particles, and specifically, the masterbatch is made by the way of melt mixing and extrusion granulation using a twin-screw extruder; the easy-peeling masterbatch particles, resin-type adhesive particles and PE heat-sealing particles (including (40% LDPE and 60% LLDPE)) are melt co-extruded in an extruder to obtain a heat-sealing and easy-peeling layer, and the resin-type adhesive particles are the intermediate adhesive film layer in the heat-sealing and easy-peeling layer after extrusion; the total thickness of the heat-sealing and easy-peeling layer is 35 μm, among which, the thickness of the intermediate adhesive film layer is 4 μm, and the thickness of the film layer extruded from the easy-peeling masterbatch particles is 7 μm;

[0081] The inorganic particles are talcum powder, and the median diameter of the inorganic particles is 6 μm. The inorganic particles have the following three functions: one is to act as a slip agent in the formula, the second is to be able to adjust the cohesive force in the film layer so as to adjust the easy-peeling effect, and the third is to make the surface of the lid film concave and convex towards the inside of the cup, increasing the contact angle;

[0082] The matrix resin is polypropylene, and the resin-type adhesive particles are maleic anhydride grafted polypropylene. Due to the poor compatibility between the polypropylene matrix resin and the PE heat-sealing particles, the addition of the resin-type adhesive particles can make the obtained heat-sealing and easy-peeling layer more stable and not easy to delaminate.

[0083] The dispersant is calcium stearate. This amphiphilic small molecule dispersant contains both polar and non-polar groups and has hydrophilic and lipophilic properties. Using it to disperse inorganic particles can enhance the interaction between inorganic particles and the matrix resin, making the inorganic particles not easy to fall off from the matrix resin; the slip agent is erucamide, which can adjust the surface slip performance.

[0084] S2. Preparation of the anti-sticking coating:

[0085] The silicone anti-sticking agent is dissolved in the propanol solvent to make a 10 wt% anti-sticking coating solution, and the silicone anti-sticking agent is a silane containing methoxy;

[0086] The anti-sticking coating solution is coated on the side of the heat-sealing and easy-peeling layer containing inorganic particle components. Specifically, it is coated by a gravure roll on a coater, and the coating amount is 0.4 gsm. Finally, it is dried in an oven to obtain the anti-sticking coating; during this solvent drying process, because the inorganic particle components in the heat-sealing and easy-peeling layer contain groups such as hydroxyl and carboxyl, the active groups of the silicone anti-sticking agent can react with them, so as to rivet to the surface of the heat-sealing and easy-peeling layer, making the non-sticking milk effect more lasting, the anti-scratch effect better, and there will be no problem of coating peeling off.

[0087] S3. Preparation of printing layer and barrier layer: The MPET barrier layer is compounded on the other side of the heat-sealable easy-peel layer through polyurethane adhesive, and the printing layer is compounded on the surface of the barrier layer through polyurethane adhesive. The thickness of the barrier layer is 12 μm. The printing layer is PET printed with a pattern and has a thickness of 12 μm. The thickness of the two polyurethane adhesive layers is 3 μm.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Based on the present invention and the above description, relevant personnel can make various changes and modifications without departing from the technical idea of ​​the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0089] After heat-sealing the non-milk-sticky easy-to-peel composite cover films of the above-mentioned embodiments with cups / bottles / trays of different materials, the cover films were peeled off by a clamp in an electronic tensile testing machine, and the change of peeling force when the cover films were torn off was observed and measured. The test results are shown in Table 1 below:

[0090] Table 1:

[0091]

[0092]

[0093] It can be seen from Table 1 above that the non-stick milk easy-to-peel composite cover film of each embodiment can match cups / bottles / trays of various materials, and can be heat-sealed with materials such as PE, PET, PP and PS. It has a wide range of applications, is easy to peel after heat sealing, has a smooth lid opening feel, and provides a good consumer experience. More importantly, its anti-stick coating has a better anti-scratch effect, and there will be no problem of coating shedding, making the non-stick milk effect more durable.

Claims

1. A method for making a non-milk-sticky and easy-to-remove composite cover film, characterized in that: The following steps are involved: S1. Preparation of heat-sealable peelable layer: The following raw materials in parts by weight: 30-90 parts of base resin, 10-50 parts of inorganic particles, 1-15 parts of dispersant and 0.5-5 parts of lubricant are pre-mixed and granulated to prepare easy-peel masterbatch particles; the easy-peel masterbatch particles and PE heat-sealing particles are melt-coextruded to prepare a heat-sealing easy-peel layer; The inorganic particles are one of silica and talc or a mixture of the two, and the median diameter of the inorganic particles is 2-10 μm; S2. Preparation of anti-stick coating: The organic silicon anti-sticking agent is dissolved in a solvent to prepare an anti-sticking coating liquid, wherein the organic silicon anti-sticking agent is an organic silicon resin containing one or more active groups of amino, epoxy, methoxy and ethoxy groups, and the solvent is one or more of water, alcohol organic solvent and ester organic solvent; The anti-sticking coating liquid is coated on the side of the heat-sealable peeling layer containing the inorganic particle component, and finally the solvent is dried to obtain the anti-sticking coating.

2. The method for making a non-milk-sticky and easy-to-peel composite cover film according to claim 1, characterized in that: In step S1, the base resin is a polyethylene base resin or a polypropylene base resin; The polyethylene base resin is one of polyethylene, ethylene-acrylate copolymer, and ethylene-vinyl acetate copolymer; The polypropylene-based matrix resin is polypropylene, maleic acid-modified polypropylene or chlorinated polypropylene.

3. The method for making a non-milk-sticky and easy-to-peel composite cover film according to claim 2, characterized in that: When the base resin is a polypropylene base resin, step S1 also includes resin-type adhesive particles, which are melt-coextruded easy-to-peel masterbatch particles, resin-type adhesive particles and PE heat-sealing particles to obtain a heat-sealable easy-to-peel layer. The resin-type adhesive particles are melt-extruded to form an intermediate adhesive film layer in the heat-sealable easy-to-peel layer.

4. The method for making a non-milk-sticky and easy-to-peel composite cover film according to claim 3, characterized in that: The resin-type bonding particles are ethylene-acrylate copolymer or maleic anhydride grafted polypropylene.

5. The method for making a non-milk-sticky and easy-to-peel composite cover film according to claim 1, characterized in that: In step S1, the dispersant is one of polyethylene wax, oleamide, stearate, titanate coupling agent, and polyethylene-maleic acid copolymer.

6. The method for making a non-milk-sticky and easy-to-peel composite cover film according to claim 1, characterized in that: In step S1, the lubricant is erucamide.

7. The method for making a non-milk-sticky and easy-to-peel composite cover film according to claim 1, characterized in that: In step S2, the coating method is roller coating or spray coating, and the coating amount is 0.1-1.0 gsm.

8. A non-milk-sticky easy-to-peel composite cover film prepared by the method according to any one of claims 1 to 7, characterized in that: The invention comprises a heat-sealing easy-peeling layer and an anti-sticking coating. The anti-sticking coating is coated and compounded on the side of the heat-sealing easy-peeling layer containing inorganic particle components according to the method.

9. The non-milk-sticky and easy-to-peel composite cover film according to claim 8, characterized in that: It also includes a printing layer and a barrier layer. The barrier layer is compounded on the other side of the heat-sealable and easy-to-peel layer through a polyurethane adhesive, and the printing layer is compounded on the surface of the barrier layer through a polyurethane adhesive. The barrier layer is AL or MPET, and the printing layer is PET or BOPP or nylon film or paper printed with patterns.

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