An ultra-high barrier homogeneous composite packaging film and its preparation process

Abstract

The present invention discloses an ultra-high barrier homogeneous composite packaging film and its preparation process, belonging to the technical field of packaging materials. The ultra-high barrier homogeneous composite packaging film of the present invention includes a substrate layer, an ink layer, a barrier layer, and a heat-sealing layer. The substrate layer is a BOPP film, the ink layer is a water-based ink, the barrier layer is a VMBOPP film, and the heat-sealing layer is a PE composite film. The BOPP film is composed of the following raw materials in parts by mass: 60-70 parts of polypropylene, 15-22 parts of hyperbranched polymer-modified POE, 10-18 parts of ethylene-vinyl acetate copolymer, 0.1-0.5 parts of a nucleating agent, and 0.1-0.4 parts of an antioxidant. The preparation process of the ultra-high barrier homogeneous composite packaging film of the present invention is simple, the structural barrier property is stable, it has ultra-high oxygen barrier property and water vapor barrier property, excellent mechanical strength, toughness, and resistance to high and low temperatures, and the heat-sealing process is easy to control, and the flatness of the sealed edge after packaging is improved. Using a single polyolefin material, the raw materials are environmentally friendly, and the barrier performance equivalent to that of aluminum foil can be obtained, reducing the cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of packaging materials, and particularly relates to an ultra-high barrier homogeneous composite packaging film and a preparation process thereof. Background Art

[0002] A high-barrier packaging film refers to a material with high barrier properties to oxygen, water vapor, carbon dioxide, aroma, etc., and is mainly used in fields such as food, cigarettes, medicine, and chemical packaging that require freshness preservation and aroma preservation. In existing packaging materials, in order to obtain good mechanical properties and barrier properties, a packaging structure containing metal aluminum foil and polyester is usually used. However, the waste packaging of such a structure can usually only be incinerated, and the packaging waste cannot meet the requirements of circular regeneration. In order to realize the recycling of waste plastic packaging, a single-material packaging structure has gradually been proposed.

[0003] Existing high-barrier single-material packaging films are basically polyolefin composite packaging films, which are divided into a base material layer, a printing layer, a barrier layer, and a heat-sealing layer according to their functions. Conventional polyolefin base material layers are BOPP (biaxially oriented polypropylene) and PE (polyethylene), which have excellent mechanical strength and toughness, but have insufficient barrier properties to small molecules such as oxygen and water vapor. BOPP has good printability and chemical stability, but general heat resistance, and is prone to film shrinkage during heat sealing, affecting the heat-sealing effect; PE is soft, has good extensibility, and good heat-sealing properties, but has poor printability and poor heat resistance.

[0004] Existing barrier layers generally use aluminized polyolefin films, aluminum-plastic polyolefin composite films, and EVOH films. The aluminized film forms a dense and uniform filter film on the surface of the base film by vacuum aluminizing technology, and has excellent barrier properties. However, the equipment investment is large, the process requirements are high, the film layer is opaque, the folding resistance is poor, and it is difficult to recycle; the aluminum-plastic composite film is composed of aluminum foil and plastic, and has good oxygen and moisture barrier properties, but the film layer is opaque, cannot be microwave-treated, and is difficult to recycle; the EVOH film is easy to process, the film is transparent, and has good barrier properties. When burned, it only produces CO 2 and H 2 O, and belongs to an environmentally friendly material. However, if the barrier property requirements are to be met, the EVOH film layer is relatively thick, and there are also certain requirements for processing equipment, the equipment investment cost is relatively high, and the barrier property decreases under high humidity conditions, affecting the use effect and service life of the packaging material.

[0005] Common heat-sealing layer materials include polyethylene, chlorinated polyethylene, EVA, polypropylene, hot melt adhesives, etc. Among them, polyethylene has good heat-sealing performance, moisture-proof, and cold-resistant properties. However, it is easily scratched and perforated, has average gas barrier properties, is not resistant to high temperatures, has poor adhesion, and poor printing performance; chlorinated polyethylene has good heat-sealing performance, cold resistance, and good oil resistance. However, its cold resistance increases with the chlorine content, and the processing is complex. Incineration will produce carcinogenic dioxin substances; cast polypropylene has good heat-sealing performance, moisture-proof, and average gas barrier properties, good printing performance, and is not cold-resistant; EVA has good heat-sealing performance, good low-temperature resistance, and good adhesion. However, it has poor water resistance, is easily hydrolyzed, and has poor aging resistance, thus affecting the use effect and service life of the packaging.

[0006] The invention patent CN202111204782.7 discloses a homogeneous olefin-based packaging stand-up pouch, which successively has an MDOPE printed substrate layer, a PVA barrier layer, an aqueous ink layer, an adhesive layer, and an LDPE heat-sealing layer from the outside to the inside. It has certain barrier properties and is green and environmentally friendly. However, the adhesion of the heat-sealing layer of this packaging stand-up pouch is not good, and it needs to use an aqueous polyurethane adhesive to ensure the bonding effect between the ink layer and the heat-sealing layer; each layer of film is relatively thick, increasing the cost and use effect; the barrier layer uses PVA, and its water vapor barrier performance is average, affecting the service life of the present invention. The invention patent CN202211316241.8 discloses a high-barrier heavy packaging one-way breathable bag. A one-way air valve is provided on the front of the bag body. The film composite structure of the bag body successively includes a BOPET film layer, an EVA layer, a PE modified layer with a filter film plated on the surface, an EMA layer, and an LDPE layer. It has excellent softness and airtightness, low oxygen permeability, and improves the interlayer peel strength between the barrier functional layer, the heat-sealing layer, and the printed substrate layer. However, the adhesion between the heat-sealing layer and the barrier layer is not good, and an EMA layer needs to be added between the layers to improve the bonding force between the layers, increasing the cost and process flow; the barrier layer is a self-made aluminized ultra-high-barrier homogeneous composite packaging film, which requires the addition of large equipment and high process requirements, increasing the labor cost. Moreover, the thinner the thickness of the aluminized film, the higher the requirements for equipment, process, etc. The best existing aluminized film can only reach 8μm, and the conventional aluminized film is 15μm; in addition, the substrate layer of this patent is made of PET material, which does not belong to polyolefin material and cannot meet the requirements of circular regeneration. Summary of the Invention

[0007] The main object of the present invention is to provide an ultra-high-barrier homogeneous composite packaging film with simple preparation process, stable structural barrier properties, ultra-high oxygen barrier property and water vapor barrier property, excellent mechanical strength, toughness and high and low temperature resistance, and easy control of the heat-sealing process, improving the flatness of the sealed edge after packaging; each structural layer of this homogeneous composite film uses a single polyolefin material, with environmentally friendly raw materials, and can obtain the barrier performance equivalent to that of aluminum foil, reducing the cost.

[0008] To achieve the object of the present invention, the present invention provides an ultra-high barrier homogeneous composite packaging film, which is sequentially provided with a substrate layer, an ink layer, a barrier layer and a heat-sealing layer from the outside to the inside. The substrate layer is a BOPP film, the ink layer is a water-based ink, the barrier layer is a VMBOPP film, and the heat-sealing layer is a PE composite film.

[0009] The present invention uses an aluminized biaxially oriented polypropylene film (VMBOPP film) as the barrier layer, which has better oxygen barrier property, water vapor barrier property, aroma retention property and structural stability, enhances the bonding force with the heat-sealing layer, so that it does not need to use an adhesive to bond with the heat-sealing layer. At the same time, it also has good heat insulation and light reflection properties, which helps to maintain the temperature of the items in the packaging bag.

[0010] The BOPP film is obtained by stretching a PP film in both the longitudinal and transverse directions. The PP film is composed of the following raw materials in parts by mass: 60-70 parts of polypropylene, 15-22 parts of hyperbranched polymer-modified POE, 10-18 parts of ethylene-vinyl acetate copolymer, 0.1-0.5 part of nucleating agent and 0.1-0.4 part of antioxidant.

[0011] The BOPP film of the present invention is based on PP and is prepared by interacting with EVA and hyperbranched polymer-modified POE. It has good transparency, excellent mechanical properties, and significantly improved heat resistance and heat-sealing properties, that is, heat resistance > 130 °C, shrinkage rate < 2% (120 °C, 10 minutes); combining three polyolefin materials to make a film, so that the BOPP film has excellent oxygen barrier property and water vapor barrier property, can ensure barrier stability, and can maintain the quality stability of the products in the film. The addition of hyperbranched polymer-modified POE makes the components of the BOPP film have excellent compatibility, and will not reduce the crystallization performance of polyolefin due to the addition of hyperbranched polymer. On the contrary, it also improves the strength and flexibility of the BOPP film, and at the same time significantly improves the high temperature resistance, waterproofness, gas barrier property and weather resistance of BOPP; the addition of EVA not only improves the water vapor barrier property and oxygen barrier property of the BOPP film, but also improves the impact resistance of the BOPP film, and ensures that the BOPP film has excellent heat resistance and chemical corrosion resistance, and extends the service life of the present invention.

[0012] Further, the hyperbranched polymer-modified POE is prepared by modifying POE with a hydroxyl-terminated hyperbranched polyester, and its preparation method includes the following steps:

[0013] S1. Mix appropriate proportions of POE, acrylic monomer, styrene monomer and initiator DCP evenly, and then place them in a twin-screw extruder for melt grafting reaction, and extrude and pelletize to obtain POE-g-AA;

[0014] S2. Add hyperbranched polymer, POE-g-AA and an appropriate amount of tetrabutyl titanate into a reaction kettle, then introduce nitrogen, heat up to 170 - 180 °C, stir and react for 2 - 3 h, distill to remove water, cool naturally and simultaneously evacuate for 5 - 10 min to obtain hyperbranched polymer modified POE.

[0015] Further, the addition amount of the acrylic acid monomer is 2 - 4% of the mass of the POE;

[0016] The addition amount of the styrene monomer is 1.5 - 3% of the mass of the POE;

[0017] The addition amount of the initiator DCP is 0.3 - 0.6% of the mass of the POE;

[0018] The addition amount of the hyperbranched polymer is 5 - 8% of the mass of the POE-g-AA;

[0019] The addition amount of the tetrabutyl titanate is 0.03 - 0.06% of the mass of the POE-g-AA.

[0020] The hyperbranched polymer modified POE of the present invention is formed by reacting POE grafted with acrylic acid with hydroxyl-terminated hyperbranched polyester. Using the method of the present invention to modify POE with hydroxyl-terminated hyperbranched polyester not only improves the mechanical strength, thermal stability and weather resistance of POE, but also significantly improves the high temperature resistance and gas barrier property of the BOPP film, and is not prone to shrinkage and curling during the heat sealing process, ensuring the flatness of the sealed edge of the formed product; improving the compatibility between PP and EVA, and then improving the mechanical strength and impact resistance of the BOPP film, so that the packaging bag is not easily broken after the heavy object falls, ensuring the use quality of the product and extending the service life of the product.

[0021] Further, the melt index of the ethylene-vinyl acetate copolymer at 190 °C and 2.16 Kg load is 2 - 6 g / 10 min, and the VA content is 10 - 16 wt%;

[0022] The nucleating agent is an organic phosphate nucleating agent;

[0023] The antioxidant is any one of antioxidant TNP, antioxidant 264, antioxidant 164 or antioxidant DNP.

[0024] The preferred combination of ethylene-vinyl acetate copolymer, nucleating agent and antioxidant can ensure that the BOPP film achieves comprehensive properties such as the mechanical properties, high barrier property and high temperature resistance required by the present invention.

[0025] Further, the water-based ink is PE water-based ink or acrylic water-based ink.

[0026] Further, the PE composite film is composed of the following raw materials in parts by mass: 30 - 50 parts of polyethylene composite, 10 - 20 parts of polyolefin elastomer, 5 - 8 parts of maleic anhydride grafted polyethylene, and 25 - 45 parts of second ethylene - vinyl acetate copolymer.

[0027] The PE composite film made of components such as polyethylene composite, polyolefin elastomer, maleic anhydride grafted polyethylene, and ethylene - vinyl acetate copolymer has excellent low - temperature resistance, heat - sealability, and water resistance, further improving the oxygen barrier property, water vapor barrier property, and fragrance retention property of the present invention; it also has excellent adhesion or printability, enabling no adhesive to be added between the heat - seal layer and the barrier layer, reducing costs and the processing process. The addition of polyolefin elastomer POE improves the compatibility between the components of the PE composite film, making the PE composite film have better flexibility and elasticity, and improving the heat - sealability, low - temperature resistance, and water resistance of the PE composite film, etc.; the addition of ethylene - vinyl acetate copolymer improves the heat - sealability, impact resistance, toughness, and low - temperature resistance of the PE composite film, etc., and makes the PE composite film have better adhesion, while improving the gas barrier property and water resistance of the PE composite film.

[0028] Further, the polyethylene composite is mixed by low - density polyethylene, linear low - density polyethylene, and metallocene polyethylene in a mass ratio of 2:1:3;

[0029] The second ethylene - vinyl acetate copolymer has a melt index of 25 g / 10 min at 190 °C and a 2.16 Kg load, and a VA content of 28 wt%.

[0030] The present invention uses a mixture of low - density polyethylene, linear low - density polyethylene, and metallocene polyethylene in a mass ratio of 2:1:3 as the matrix of the heat - seal layer. The three cooperate with each other, making the heat - seal layer have better heat - sealability, mechanical strength, and barrier performance, and improving the low - temperature resistance and puncture resistance of the heat - seal layer, significantly extending the service life of the present invention. Selecting an ethylene - vinyl acetate copolymer with appropriate parameters can ensure that the PE composite film has better heat - sealability and adhesiveness.

[0031] Further, the thickness of the base material layer is 10 - 25 μm;

[0032] The thickness of the barrier layer is 12 - 15 μm;

[0033] The thickness of the heat - seal layer is 30 - 60 μm.

[0034] It should be noted that the setting of the thickness of functional layers such as the base material layer and the heat - seal layer can be designed according to different packaging materials. The layer thicknesses designed in the present invention only illustrate that using the film layers within this thickness range can also meet the required performance requirements.

[0035] The present invention also provides a preparation process for an ultra-high barrier homogeneous composite packaging film, which specifically includes the following steps:

[0036] P1. Mix the raw materials of the PP film to obtain a mixed material, melt and extrude the mixed material through a twin-screw extruder, where the screw temperature is 200 - 210 °C and the die head temperature is 210 - 220 °C. Then, blow the film to form a film bubble and cool it, and then perform longitudinal and transverse biaxial stretching to obtain a base material layer.

[0037] P2. After cooling the base material layer to 30 - 35 °C, perform corona treatment, and then print an ink layer on one side of the corona-treated surface of the base material layer. After printing, dry it and cool it to room temperature.

[0038] P3. Coat an aqueous polyurethane adhesive on the aluminized side surface of the VMBOPP film, and press a composite layer of the base material layer and the ink layer on it, where the ink layer faces the VMBOPP film, and the pressing temperature is 60 - 80 °C.

[0039] P4. Add the raw materials of the PE composite film into a casting machine, heat it to 135 - 145 °C to melt, and then let it flow out through the flat die head of the casting machine. Press it against the composite layer composed of the base material layer, the ink layer, and the VMBOPP film between two closely contacting rollers to obtain a heat-sealing layer that is closely attached to the VMBOPP film. Press it at 60 - 80 °C for 0.5 - 1 h, and cool it to room temperature to obtain the ultra-high barrier homogeneous composite packaging film.

[0040] Further, the process of longitudinal and transverse biaxial stretching in step P1 is as follows: First, longitudinally stretch the film bubble 5 times at 130 °C, then transversely stretch it 8 times at 170 °C, and finally perform heat setting treatment at 180 °C for 5 - 10 s.

[0041] The present invention has achieved the following beneficial effects:

[0042] 1. For the ultra-high barrier homogeneous composite packaging film provided by the present invention, its base material layer is a BOPP film, which is based on PP, and is prepared by adding hyperbranched polymer-modified POE and ethylene-vinyl acetate copolymer and other components and performing longitudinal and transverse biaxial stretching at appropriate multiples. Its heat distortion temperature is increased from the original 124 °C to above 140 °C, and it has excellent high-temperature resistance and heat-sealing performance. At the same time, it has excellent mechanical strength, toughness, gas barrier property, and weather resistance, etc. The BOPP film of the present invention has better heat-sealing property and thermal stability by designing appropriate materials and adjusting appropriate raw material ratios. At the same time, it also reduces the heat shrinkage rate of the BOPP film, making the thermal deformation temperature difference value between it and the heat-sealing layer material larger, so that the edge-sealing effect is good when making packaging bags, improving the product yield rate and saving costs.

[0043] 2. By designing the formulation and raw material ratio of the PE composite material and using the cast film process to obtain the PE composite film as the heat-sealing layer, the present invention not only has excellent heat-sealing performance and low-temperature resistance, but also improves the gas barrier property, water resistance, printability, high-temperature resistance and toughness of the heat-sealing layer, ensuring that the heat-sealing layer is not easily punctured and enabling it to adapt to various liquid and powder packaging with barrier requirements.

[0044] 3. The difference in heat distortion temperature between the base material layer and the heat-sealing layer of the present invention is greater than 40 °C, significantly improving the heat-sealing process of the present invention. The heat-sealing process is easy to control, the sealing strength is high, and it does not affect the comprehensive performance of the base material layer.

[0045] 4. The composite packaging film of the present invention is composed of a base material layer, an ink layer, a barrier layer and a heat-sealing layer. The proportion of polyolefin material in the raw materials is > 90%, which is environmentally friendly and easily available. The processing technology is simple and easy to control. There is good adhesion performance between the film layers and they are not easily peeled off. Moreover, the film layers interact with each other, thereby ensuring that the present invention has ultra-high barrier properties, high fragrance retention performance, high heat-sealing performance, excellent high and low temperature resistance, high wear and corrosion resistance, extending the service life of the coated composite film, and broadening the application field of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic structural diagram of the ultra-high barrier homogeneous composite packaging film of the present invention.

[0047] Reference numerals in the drawings: 1. Base material layer; 2. Ink layer; 3. Barrier layer; 4. Heat-sealing layer. DETAILED DESCRIPTION OF THE INVENTION

[0048] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0049] As Figure 1 shown, the present invention provides a preparation process for an ultra-high barrier homogeneous composite packaging film, which specifically includes the following steps:

[0050] P1. Mix the raw materials of the PP film to obtain a mixed material, melt and extrude the mixed material through a twin-screw extruder, where the screw temperature is 200 - 210 °C and the die head temperature is 220 °C. Then, blow the film to form a film bubble and cool it, and then perform longitudinal and transverse biaxial stretching, that is, first longitudinally stretch the film bubble 5 times at 130 °C, then transversely stretch it 8 times at 170 °C, and finally perform heat setting treatment at 180 °C for 5 - 10 s to obtain the base material layer 1. Preferably, the thickness of the base material layer 1 is 10 - 25 μm.

[0051] Preferably, the PP film is composed of the following raw materials in parts by mass: 60-70 parts of polypropylene, 15-22 parts of hyperbranched polymer-modified POE, 10-18 parts of ethylene-vinyl acetate copolymer, 0.1-0.5 part of nucleating agent, and 0.1-0.4 part of antioxidant.

[0052] Preferably, the polypropylene is selected from Caltex Korea, with the model number of PP H240M.

[0053] Preferably, the melt index of the ethylene-vinyl acetate copolymer at 190 °C and under a load of 2.16 Kg is 2-6 g / 10 min, and the VA content is 10-16 wt%. In the examples of the present invention, preferably, the EVA is selected from DuPont of the United States, with the model number of EVA 660.

[0054] Preferably, the nucleating agent is an organic phosphate nucleating agent. In the examples of the present invention, preferably, the nucleating agent is selected from Adeka, with the model number of NA-21.

[0055] Preferably, the antioxidant is any one of antioxidant TNP, antioxidant 264, antioxidant 164, or antioxidant DNP.

[0056] Preferably, the hyperbranched polymer-modified POE is prepared by modifying POE with a hydroxyl-terminated hyperbranched polyester. By mass, its preparation method includes the following steps:

[0057] S1. By mass, mix 100 parts of POE, 2-4 parts of acrylic acid monomer, 1.5-3 parts of styrene monomer, and 0.3-0.6 part of initiator DCP evenly, then place them in a twin-screw extruder for melt grafting reaction, and extrude and pelletize. The extrusion temperature is 170-180 °C, and the screw speed is 60 r / min to obtain POE-g-AA.

[0058] Preferably, the POE is selected from ExxonMobil, with the model number of POE 3000.

[0059] S2. By mass, add 5-8 parts of hydroxyl-terminated hyperbranched polyester, 100 parts of POE-g-AA, and 0.03-0.06 part of tetrabutyl titanate to a reaction kettle, then introduce nitrogen, heat up to 170-180 °C, stir and react for 2-3 h, distill to remove water, cool naturally and simultaneously evacuate for 5-10 min to obtain the hyperbranched polymer-modified POE.

[0060] Preferably, the hydroxyl-terminated hyperbranched polyester is selected from Wuhan Hyperbranched Resin Technology Co., Ltd., with the model number of HyPer H20 or HyPer H40.

[0061] P2. After reducing the substrate layer 1 to 30 - 35°C, corona treatment, cleaning, and static elimination treatment are carried out, and then the ink layer 2 is printed on one side of the corona-treated surface of the substrate layer 1. After printing, it is dried and cooled to room temperature.

[0062] Preferably, the ink layer 2 is a water-based ink; preferably, the water-based ink is a PE water-based ink or an acrylic water-based ink. In the embodiments of the present invention, preferably, the water-based ink is a PE water-based ink, selected from Shenzhen Dahe Ink Technology, with the model number 82 series.

[0063] P3. The water-based polyurethane adhesive is coated on the aluminized side surface of the VMBOPP film, and the composite layer of the substrate layer 1 and the ink layer 2 is pressed thereon, where the ink layer 2 faces the VMBOPP film. The pressing temperature is 60 - 80°C, and the pressing time is 10 - 15 s, thus obtaining the barrier layer 3.

[0064] Preferably, the thickness of the barrier layer 3 is 12 - 15 μm.

[0065] Preferably, the VMBOPP film is selected from Foshan Color Dragon Coated Packaging Materials Co., Ltd., and the aluminum layer thickness is 1.9 Ω / □.

[0066] P4. The raw materials of the PE composite film are added to a casting machine, heated to 135 - 145°C for melting, and then flowed out through the flat head of the casting machine. It is pressed against the composite layer composed of the substrate layer 1, the ink layer 2, and the VMBOPP film between two closely contacting rollers to obtain the heat-sealing layer 4 that is in close contact with the VMBOPP film. It is pressed at 60 - 80°C for 0.5 - 1 h and cooled to room temperature to produce the ultra-high barrier homogeneous composite packaging film.

[0067] Preferably, the thickness of the heat-sealing layer 4 is 30 - 60 μm.

[0068] Preferably, the PE composite film is composed of the following raw materials in parts by mass: 30 - 50 parts of polyethylene composite, 10 - 20 parts of polyolefin elastomer (POE 3000 selected from ExxonMobil), 5 - 8 parts of maleic anhydride grafted polyethylene, and 25 - 45 parts of second ethylene-vinyl acetate copolymer.

[0069] Preferably, the polyethylene composite is mixed from low-density polyethylene (all selected from Shanghai Petrochemical LDPE, model N220), linear low-density polyethylene (all selected from Saudi Exxon LL6201RQ in the embodiments of the present invention), and metallocene polyethylene (all selected from DowDuPont 5410G in the embodiments of the present invention) in a mass ratio of 2:1:3.

[0070] Preferably, the second ethylene-vinyl acetate copolymer has a melt index of 25 g / 10 min and a VA content of 28 wt% at 190 °C under a load of 2.16 Kg; the EVA in the polyethylene composite in the examples of the present invention is selected from LG of South Korea, with the model number EA28025.

[0071] The steps of preparing the above-mentioned super-barrier homogenized composite packaging film into a packaging bag are as follows: cutting and forming the obtained high-barrier and high-fragrance-preserving coated composite film according to the set size, then making a bag through a heat-sealing process, and then engraving a laser easy-tear opening to obtain the packaging bag of the required product. Among them, the heat-sealing process conditions are: the heat-sealing temperature is 110-130 °C, and the pressure is 3-6 kg / cm 2 .

[0072] The super-barrier homogenized composite packaging film of the present invention will be described below with reference to specific examples.

[0073] PP film in the substrate layer 1 of Example 1

[0074] The PP film of this example is composed of the following raw materials in parts by mass: 60 parts of polypropylene, 22 parts of hyperbranched polymer-modified POE, 18 parts of ethylene-vinyl acetate copolymer (EVA 660), 0.2 part of nucleating agent NA-21, and 0.2 part of antioxidant TNP.

[0075] Calculated by mass, the preparation method of the above-mentioned hyperbranched polymer-modified POE includes the following steps:

[0076] S1. Calculated by mass, mix 100 parts of POE, 2 parts of acrylic acid monomer, 1.5 parts of styrene monomer, and 0.3 part of initiator DCP evenly, then place them in a twin-screw extruder for melt grafting reaction, and extrude and pelletize. The extrusion temperature is 170-180 °C, and the screw speed is 60 r / min to obtain POE-g-AA.

[0077] S2. Calculated by mass, add 5 parts of hyperbranched polyester with terminal hydroxyl groups HyPer H20, 100 parts of POE-g-AA, and 0.04 part of tetrabutyl titanate to the reaction kettle, then introduce nitrogen, heat up to 170 °C, stir and react for 3 h, distill off water, cool naturally and simultaneously evacuate to 0.9 MPa and keep it for 10 min to obtain hyperbranched polymer-modified POE.

[0078] Mix the raw materials of the above PP film, and the mixture is melt-extruded and pelletized in a twin-screw extruder, where the screw temperature is 200-210 °C and the die head temperature is 220 °C to obtain PP pellets.

[0079] The obtained PP pellets are tested according to the standard of GB / T 1634-2019, and its heat distortion temperature is detected to be 142 °C.

[0080] PP film in the substrate layer 1 of Example 2

[0081] The PP film of this example is composed of the following raw materials in parts by mass: 70 parts of polypropylene, 15 parts of hyperbranched polymer modified POE, 15 parts of ethylene-vinyl acetate copolymer (EVA 660), 0.4 part of nucleating agent NA-21, and 0.2 part of antioxidant 264.

[0082] By mass, the preparation method of the above hyperbranched polymer modified POE includes the following steps:

[0083] S1. By mass, mix 100 parts of POE, 4 parts of acrylic acid monomer, 3 parts of styrene monomer, and 0.5 part of initiator DCP evenly, then place them in a twin-screw extruder for melt grafting reaction, extrude and pelletize. The extrusion temperature is 170 - 180 °C, and the screw speed is 60 r / min to obtain POE-g-AA.

[0084] S2. By mass, add 8 parts of hyperbranched polyester with terminal hydroxyl groups HyPer H40, 100 parts of POE-g-AA, and 0.06 part of tetrabutyl titanate to the reaction kettle, then introduce nitrogen, heat up to 180 °C, stir and react for 3 h, distill and remove water, cool naturally and at the same time evacuate to 1.0 MPa and keep for 8 min to obtain hyperbranched polymer modified POE.

[0085] Detect the above PP film raw materials according to the method of Example 1. The heat distortion temperature of the PP film of Example 2 is 145 °C.

[0086] PP film in the substrate layer 1 of Example 3

[0087] The PP film of this example is composed of the following raw materials in parts by mass: 65 parts of polypropylene, 18 parts of hyperbranched polymer modified POE, 17 parts of ethylene-vinyl acetate copolymer (EVA 660), 0.3 part of nucleating agent NA-21, and 0.2 part of antioxidant TNP.

[0088] By mass, the preparation method of the above hyperbranched polymer modified POE includes the following steps:

[0089] S1. By mass, mix 100 parts of POE, 3 parts of acrylic acid monomer, 2 parts of styrene monomer, and 0.4 part of initiator DCP evenly, then place them in a twin-screw extruder for melt grafting reaction, extrude and pelletize. The extrusion temperature is 170 - 180 °C, and the screw speed is 60 r / min to obtain POE-g-AA.

[0090] S2. Add 7 parts by mass of hydroxyl-terminated hyperbranched polyester HyPer H20, 100 parts of POE-g-AA, and 0.05 part of tetrabutyl titanate into a reaction kettle, then introduce nitrogen, heat up to 180 °C, stir and react for 3 h, distill to remove water, cool naturally and simultaneously evacuate to 1.0 MPa and hold for 8 min to obtain hyperbranched polymer-modified POE.

[0091] The above PP film raw materials were tested according to the method of Example 1. The heat distortion temperature of the PP film of Example 3 was 146 °C.

[0092] The PP film in the substrate layer 1 of Example 4

[0093] The raw materials, preparation process, etc. of the PP film in this example are the same as those in Example 3. The difference is that the mass fractions of the raw materials of the PP film in Example 4 are different, namely: 65 parts of polypropylene, 20 parts of hyperbranched polymer-modified POE, 15 parts of ethylene-vinyl acetate copolymer (EVA 660), 0.3 part of nucleating agent NA-21, and 0.2 part of antioxidant TNP.

[0094] The above PP film raw materials were tested according to the method of Example 1. The heat distortion temperature of the PP film of Example 4 was 150 °C.

[0095] Comparative Example 1

[0096] The raw materials, preparation process, etc. of the PP film in this Comparative Example 1 are the same as those in Example 4. The difference is that hyperbranched polymer-modified POE was not added in this Comparative Example 1, and the addition amount of polypropylene was 85 parts.

[0097] After testing, the heat distortion temperature of the PP film of Comparative Example 1 was 122 °C.

[0098] Comparative Example 2

[0099] The raw materials, preparation process, etc. of the PP film in this Comparative Example 2 are the same as those in Example 4. The difference is that hyperbranched polymer-modified POE was not added in this Comparative Example 2, and 20 parts of a mixture of POE and hydroxyl-terminated hyperbranched polyester HyPerH20 with a mass ratio of 100:7 was added.

[0100] After testing, the heat distortion temperature of the PP film of Comparative Example 2 was 105 °C.

[0101] Comparative Example 3

[0102] The raw materials, preparation process, etc. of the PP film in this Comparative Example 3 are the same as those in Example 4. The difference is that in this Comparative Example 3, hydroxyl-terminated hyperbranched polyester HyPer H20 was replaced with hydroxyl-terminated saturated polyester, and the hydroxyl-terminated saturated polyester was selected from HK7805 of Hubei Xinyuhong.

[0103] After testing, the heat distortion temperature of the PP film in Comparative Example 3 is 126 °C.

[0104] Comparative Example 4

[0105] The raw materials, preparation process, etc. of the PP film in this Comparative Example 4 are the same as those in Example 4. The difference is that ethylene-vinyl acetate copolymer is not added in this Comparative Example 4, and the addition amount of polypropylene is 80 parts.

[0106] After testing, the heat distortion temperature of the PP film in Comparative Example 4 is 143 °C.

[0107] Example 5 PE composite film

[0108] The PE composite film in this Example 5 is composed of the following raw materials in parts by mass: 42 parts of polyethylene composite, 18 parts of polyolefin elastomer, 7 parts of maleic anhydride grafted polyethylene, and 33 parts of second ethylene-vinyl acetate copolymer (EA28025). Among them, the polyethylene composite is composed of LDPE (N220), LLDPE (LL6201 RQ), and metallocene polyethylene (5410G) mixed in a mass ratio of 2:1:3.

[0109] Mix the above raw materials of the PE composite film, and the mixture is melt extruded and granulated by a twin-screw extruder, where the screw temperature is 160 - 180 °C and the die head temperature is 190 °C to obtain PE pellets.

[0110] The obtained PE pellets are tested according to the standard of GB / T 1634-2019. After testing, its heat distortion temperature is 85 °C.

[0111] Comparative Example 5

[0112] The raw materials and proportions of the PE composite film in this Comparative Example 5 are the same as those in Example 5. The difference is that polyolefin elastomer is not added in this Comparative Example 5, and the addition amount of polyethylene composite is 60 parts.

[0113] Comparative Example 6

[0114] The raw materials and proportions of the PE composite film in this Comparative Example 6 are the same as those in Example 5. The difference is that the second ethylene-vinyl acetate copolymer is not added in this Comparative Example 6, and the addition amount of polyethylene composite is 75 parts.

[0115] Comparative Example 7

[0116] The raw materials and proportions of the PE composite film in this Comparative Example 7 are the same as those in Example 6. The difference is that the polyethylene composite in this Comparative Example 7 is composed of low-density polyethylene, linear low-density polyethylene, and metallocene polyethylene mixed in a mass ratio of 5:1:2.

[0117] Comparative Example 8

[0118] The raw materials and their proportions of the PE composite film in Comparative Example 8 are the same as those in Example 6. The difference is that the second ethylene-vinyl acetate copolymer in Comparative Example 8 is selected from DuPont of the United States, with the model of EVA 660.

[0119] Application Example 1

[0120] An ultra-high barrier homogeneous composite packaging film is made by sequentially arranging a substrate layer 1, an ink layer 2, a barrier layer 3, and a heat-sealing layer 4 from the outside to the inside. The specific preparation process is as follows:

[0121] P1. Mix the raw materials of the PP film in Example 1 to obtain a mixture, melt-extrude the mixture through a twin-screw extruder, where the screw temperature is 200 - 210 °C, the die head temperature is 220 °C, then blow the film to form a film bubble and cool it. Then, longitudinally stretch the film bubble 5 times at 130 °C, then transversely stretch it 8 times at 170 °C, and finally perform heat setting treatment at 180 °C for 8 s to obtain the substrate layer 1. The thickness of the substrate layer 1 is about 15 μm.

[0122] P2. After cooling the substrate layer 1 to 30 °C, perform corona treatment with a corona voltage of 4 kV, a corona speed of 40 m / min, and a treatment time of 8 s. Clean and remove static electricity, and then print PE water-based ink on one side of the corona surface of the substrate layer 1. After printing, dry it and cool it to room temperature to obtain the ink layer 2.

[0123] P3. Coat the aluminized side surface of the VMBOPP film (selected from Foshan Colorful Dragon Coated Film Packaging Materials Co., Ltd.) with a water-based polyurethane adhesive (Covestro U54 of Germany), and press the composite layer of the substrate layer and the ink layer 2 on it, where the ink layer 2 faces the VMBOPP film. The pressing temperature is 70 °C, and the pressing time is 12 s.

[0124] P4. Add the raw materials of the PE composite film in Example 5 to a casting machine, heat it to 140 °C to melt, then flow it out through a flat die head, and press it against the composite layer composed of the substrate layer 1, the ink layer 2, and the VMBOPP film between two closely contacting rollers to obtain the heat-sealing layer 4 that is closely attached to the VMBOPP film. Press it at 70 °C for 30 min and cool it to room temperature to prepare the ultra-high barrier homogeneous composite packaging film. Among them, the thickness of the heat-sealing layer 4 is 40 μm.

[0125] Application Example 2

[0126] The structure and preparation process of the ultra-barrier homogeneous composite packaging film in this Application Example 2 are the same as those in Application Example 1. For details, refer to Application Example 1. The difference is that the raw materials of the PP film are formulated according to Example 2.

[0127] Application Example 3

[0128] The structure and preparation process of the super-barrier homogeneous composite packaging film in Application Example 3 are the same as those in Application Example 1. For details, refer to Application Example 1. The difference is that the raw materials of the PP film are formulated according to Example 3.

[0129] Application Example 4

[0130] The structure and preparation process of the super-barrier homogeneous composite packaging film in Application Example 4 are the same as those in Application Example 1. For details, refer to Application Example 1. The difference is that the raw materials of the PP film are formulated according to Example 4.

[0131] Application Comparative Example 1

[0132] The structure and preparation process of the super-barrier homogeneous composite packaging film in this Application Comparative Example 1 are the same as those in Application Example 4. For details, refer to Application Example 4. The difference is that the raw materials of the PP film are formulated according to Comparative Example 1.

[0133] Application Comparative Example 2

[0134] The structure and preparation process of the super-barrier homogeneous composite packaging film in this Application Comparative Example 2 are the same as those in Application Example 4. For details, refer to Application Example 4. The difference is that the raw materials of the PP film are formulated according to Comparative Example 2.

[0135] Application Comparative Example 3

[0136] The structure and preparation process of the super-barrier homogeneous composite packaging film in this Application Comparative Example 3 are the same as those in Application Example 4. For details, refer to Application Example 4. The difference is that the raw materials of the PP film are formulated according to Comparative Example 3.

[0137] Application Comparative Example 4

[0138] The structure and preparation process of the super-barrier homogeneous composite packaging film in this Application Comparative Example 4 are the same as those in Application Example 4. For details, refer to Application Example 4. The difference is that the raw materials of the PP film are formulated according to Comparative Example 4.

[0139] Application Comparative Example 5

[0140] The structure and preparation process of the super-barrier homogeneous composite packaging film are the same as those in Application Example 4. For details, refer to Application Example 4. The difference is that the raw materials of the PE composite film are formulated according to Comparative Example 5.

[0141] Application Comparative Example 6

[0142] The structure and preparation process of the super-barrier homogeneous composite packaging film are the same as those in Application Example 4. For details, refer to Application Example 4. The difference is that the raw materials of the PE composite film are formulated according to Comparative Example 6.

[0143] Application Comparative Example 7

[0144] The structure and preparation process of the super-barrier homogeneous composite packaging film are the same as those in Application Example 4. For specific reference, please refer to Application Example 4. The difference is that the raw materials of the PE composite film are prepared according to Comparative Ratio 7.

[0145] Application Comparative Example 8

[0146] The structure and preparation process of the super-barrier homogeneous composite packaging film are the same as those in Application Example 4. For specific reference, please refer to Application Example 4. The difference is that the raw materials of the PE composite film are prepared according to Comparative Ratio 8.

[0147] Take the super-barrier homogeneous composite packaging film samples prepared in Application Examples 1-4 and Application Comparative Examples 1-8, and conduct tests on their gas permeability, water vapor permeability, adhesion, low-temperature resistance, etc. The test results are shown in Table 1 below.

[0148] The test methods are as follows:

[0149] Oxygen transmission rate: Tested according to the standard of GB / T 1038-2022 Test Method for Gas Permeability of Plastic Films and Sheets;

[0150] Water vapor transmission rate (37°C, 90% humidity): Tested according to the standard of GB / T 1037-2021 Test Method for Water Vapor Permeability of Plastic Films and Sheets;

[0151] Interlayer peel strength (peel strength between the heat-sealing layer and the composite layer composed of the base material layer, polyvinyl alcohol composite film and ink layer): Tested according to the standard of GB / T 8808-88 Test Method for Peel Strength of Flexible Composite Plastic Materials;

[0152] Low-temperature resistance: Tested according to the standard of GB / T 1040.2-2022 Determination of Tensile Properties of Plastics, and the tensile strength and elongation at break of the composite packaging film are tested at a test temperature of -40°C.

[0153] Table 1 Performance Test Results of Super-Barrier Homogeneous Composite Packaging Film

[0154]

[0155]

[0156] As can be seen from the test results in Table 1 above, the ultra-high-barrier homogeneous composite packaging film of the present invention has excellent heat-sealing performance and high and low-temperature resistance, and has lower oxygen transmission rate and water vapor transmission rate. Moreover, the heat-sealing layer 4 has better adhesion.

[0157] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0158] The above embodiments only express several implementation manners of the present invention, and the description thereof is relatively specific and detailed. However, it should not be construed as a limitation on the scope of the patent for the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. An ultra-high barrier homogeneous composite packaging film, comprising a substrate layer (1), an ink layer (2), a barrier layer (3) and a heat-sealing layer (4) arranged in sequence from the outside to the inside, characterized in that: The substrate layer (1) is a BOPP film, the ink layer (2) is a water-based ink, the barrier layer (3) is a VMBOPP film, and the heat-sealing layer (4) is a PE composite film; The BOPP film of the substrate layer (1) is obtained by stretching a PP film in both longitudinal and transverse directions, and the PP film is composed of the following raw materials in parts by weight: 60-70 parts of polypropylene, 15-22 parts of hyperbranched polymer modified POE, 10-18 parts of ethylene-vinyl acetate copolymer, 0.1-0.5 parts of nucleating agent and 0.1-0.4 parts of antioxidant; The ethylene-vinyl acetate copolymer has a melt index of 2-6 g / 10 min at 190° C. and a load of 2.16 kg, and a VA content of 10-16 wt %; The preparation method of the hyperbranched polymer modified POE comprises the following steps: S1. The appropriate proportion of POE, acrylic monomer, styrene monomer and initiator DCP were mixed uniformly, and then placed in a twin-screw extruder for melt grafting reaction, extruded and granulated to obtain POE-g-AA; S2. The hydroxyl-terminated hyperbranched polyester, POE-g-AA and an appropriate amount of tetrabutyl titanate were added to a reaction kettle, and then nitrogen was introduced, the temperature was raised to 170-180°C, the reaction was stirred for 2-3h, water was distilled off, and the mixture was naturally cooled and vacuumed for 5-10min to obtain a hyperbranched polymer-modified POE; The PE composite film is composed of the following raw materials in parts by weight: 30-50 parts of polyethylene compound, 10-20 parts of polyolefin elastomer, 5-8 parts of maleic anhydride grafted polyethylene and 25-45 parts of a second ethylene-vinyl acetate copolymer; The polyethylene composite is a mixture of low-density polyethylene, linear low-density polyethylene and metallocene polyethylene in a mass ratio of 2:1:3; the melt index of the second ethylene-vinyl acetate copolymer at 190°C and a load of 2.16Kg is 25g / 10min, and the VA content is 28wt%.

2. The ultra-high barrier homogeneous composite packaging film according to claim 1, characterized in that: The amount of the acrylic acid monomer added is 2-4% of the mass of the POE; The amount of the styrene monomer added is 1.5-3% of the mass of the POE; The added amount of the initiator DCP is 0.3-0.6% of the mass of the POE; The amount of the terminal hydroxyl hyperbranched polyester added is 5-8% of the mass of the POE-g-AA; The addition amount of the tetrabutyl titanate is 0.03-0.06% of the mass of the POE-g-AA.

3. The ultra-high barrier homogeneous composite packaging film according to claim 1, characterized in that: The nucleating agent is an organic phosphate nucleating agent; The antioxidant is any one of antioxidant TNP, antioxidant 264, antioxidant 164 or antioxidant DNP.

4. The ultra-high barrier homogeneous composite packaging film according to claim 1, characterized in that: The water-based ink is PE water-based ink or acrylic water-based ink.

5. The ultra-high barrier homogeneous composite packaging film according to claim 1, characterized in that: The thickness of the substrate layer (1) is 10-25 μm; The thickness of the barrier layer (3) is 12-15 μm; The thickness of the heat-sealing layer (4) is 30-60 μm.

6. A process for preparing the ultra-high barrier homogeneous composite packaging film according to any one of claims 1 to 5, characterized in that: The specific steps include: P1. The raw materials of the PP film are mixed to obtain a mixture, and the mixture is melt-extruded through a twin-screw extruder, wherein the screw temperature is 200-210°C, the die temperature is 210-220°C, and then the film is blown to form a bubble, and then cooled, and then stretched in both the longitudinal and transverse directions to obtain a substrate layer; P2. The substrate layer is cooled to 30-35°C and then corona treated, and then the ink layer (2) is printed on the corona surface of the substrate layer (1), and after printing, it is dried and cooled to room temperature; P3. coating a water-based polyurethane adhesive on the aluminum-plated side surface of the VMBOPP film, and pressing a composite layer of a substrate layer (1) and an ink layer (2) thereon, wherein the ink layer (2) faces the VMBOPP film, and pressing at a temperature of 60-80° C. to obtain a barrier layer (3); P4. The raw material of the PE composite film is added to a casting machine, heated to 135-145°C to melt, and then flows out through a flat die head, and is pressed between two closely contacting rollers toward a composite layer consisting of a substrate layer (1), an ink layer (2) and a VMBOPP film to obtain a heat-sealing layer (4) in close contact with the VMBOPP film, and is pressed at 60-80°C for 0.5-1h, and cooled to room temperature to obtain an ultra-high barrier homogeneous composite packaging film.

7. The process for preparing the ultra-high barrier homogeneous composite packaging film according to claim 6, characterized in that: The process of biaxial stretching in step P1 is: firstly stretch the film bubble longitudinally by 5 times at 130°C, then stretch it transversely by 8 times at 170°C, and finally heat-set it at 180°C for 5-10s.

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