Ultrahigh-barrier homogenized composite packaging film and preparation process thereof

Abstract

The invention discloses an ultrahigh-barrier homogenized composite packaging film and a preparation process thereof, and belongs to the technical field of packaging materials. The ultrahigh-barrier homogenized composite packaging film comprises a base material layer, an ink layer, a barrier layer and a heat sealing layer, wherein the base material layer is a BOPP film, the ink layer is water-based ink, the barrier layer is a VMBOPP film, and the heat sealing layer is a PE composite film; the BOPP film is prepared from the following raw materials in parts by mass: 60 to 70 parts of polypropylene, 15 to 22 parts of hyperbranched polymer modified POE (Polyolefin Elastomer), 10 to 18 parts of ethylene-vinyl acetate copolymer, 0.1 to 0.5 part of nucleating agent and 0.1 to 0.4 part of antioxidant. The ultrahigh-barrier homogenized composite packaging film disclosed by the invention is simple in preparation process and stable in structural barrier property, has ultrahigh oxygen barrier property and water vapor barrier property and excellent mechanical strength, toughness and high and low temperature resistance, a heat sealing process is easy to control, and the edge sealing flatness after packaging is improved; the single polyolefin material is adopted, the raw materials are environment-friendly, the barrier property of the same structure of an aluminum foil can be obtained, and the cost is reduced.

Description

Technical Field

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

[0002] High barrier packaging film refers to materials with high barrier properties to oxygen, water vapor, carbon dioxide and aroma, and is mainly used in areas such as food, cigarettes, medicine, and chemical packaging that require freshness and fragrance preservation. In order to obtain better mechanical properties and barrier properties, existing packaging materials usually use packaging structures containing metal aluminum foil and polyester. However, waste packaging of this type of structure can usually only be incinerated, and packaging waste cannot meet the recycling requirements. In order to achieve the recycling of packaging waste plastics, packaging structures made of a single material have gradually been proposed.

[0003] The existing high-barrier single-material packaging films are basically polyolefin composite packaging films, which are divided into substrate layer, printing layer, barrier layer and heat-sealing layer according to their functions. Conventional polyolefin substrate layers are BOPP (bi-stretched polypropylene) and PE (polyethylene), which have excellent mechanical strength and toughness, but have insufficient barrier properties against small molecules such as oxygen and water vapor. BOPP has good printability and good chemical stability, but average heat resistance, and the film is prone to 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] The existing barrier layer generally adopts aluminum-plated polyolefin film, aluminum-plastic polyolefin composite film, and EVOH film. Aluminum-plated film is a dense and uniform filter membrane formed on the surface of the base film by vacuum aluminum plating process. It has excellent barrier performance, but 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; aluminum-plastic composite film is composed of aluminum foil and plastic, and its oxygen and moisture barrier properties are good, but the film layer is opaque, cannot be microwaved, and is difficult to recycle; EVOH film is easy to process, transparent, and has good barrier properties. When incinerated, it only produces CO2 and H2O, and is an environmentally friendly material. However, if the barrier properties are to be achieved, the EVOH film layer is thicker and has certain requirements for processing equipment. The equipment investment cost is high, and the barrier properties decrease under high humidity conditions, affecting the use effect and life of the packaging material.

[0005] Commonly used heat-sealing layer materials are polyethylene, chlorinated polyethylene, EVA, polypropylene and hot melt adhesive, among which polyethylene has good heat-sealing properties, is moisture-proof and cold-resistant, but it is easy to be 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 properties, is cold-resistant and has good oil resistance, but its cold resistance increases with the increase of chlorine content, and its processing is complicated, and incineration will produce dioxin carcinogens; cast polypropylene has good heat-sealing properties, is moisture-proof, has average gas barrier properties, has good printability and is not cold-resistant; EVA has good heat-sealing properties, good low-temperature resistance and good adhesion, but it has poor water barrier properties, is easily hydrolyzed, and has poor aging resistance, which in turn affects the use effect and service life of the packaging.

[0006] Invention patent CN202111204782.7 discloses a homogenous olefin packaging self-supporting bag, which 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 the packaging self-supporting bag is poor, and it is necessary to use an aqueous polyurethane adhesive to ensure the bonding effect between the ink layer and the heat-sealing layer; each layer of the film is relatively thick, which increases the cost and use effect; the barrier layer uses PVA, and its water vapor barrier performance is average, which affects the service life of the present invention. Invention patent CN202211316241.8 discloses a high-barrier heavy-duty packaging one-way breathable bag, with a one-way breathable valve on the front of the bag body. The film composite structure of the bag body includes a BOPET film layer, an EVA layer, a PE modified layer coated with a filter membrane on the surface, an EMA layer and a LDPE layer in sequence. It has excellent softness and air tightness, low oxygen permeability, and improves the interlayer peeling force between the barrier functional layer and 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 strength between the layers, which increases the cost and process flow; the barrier layer is a self-made aluminum-plated ultra-high barrier homogeneous composite packaging film, which requires the addition of large-scale equipment, high process requirements, and increased labor costs. The thinner the thickness of the aluminum-plated film, the higher the requirements for equipment and process. The existing aluminum-plated film can only be 8μm at best, and the conventional aluminum-plated film is 15μm; in addition, the substrate layer of this patent is made of PET, which is not a polyolefin material and cannot meet the recycling requirements. Summary of the invention

[0007] The main purpose of the present invention is to provide an ultra-high barrier homogeneous composite packaging film with a simple preparation process, stable structural barrier properties, ultra-high oxygen barrier properties and water vapor barrier properties, excellent mechanical strength, toughness and high and low temperature resistance, and easy control of the heat sealing process, and improved edge sealing flatness after packaging; each structural layer of the homogeneous composite film adopts a single polyolefin material, the raw materials are environmentally friendly, and the barrier performance of the same structure as aluminum foil can be obtained, reducing the cost.

[0008] In order to achieve the purpose of the present invention, the present invention provides an ultra-high barrier homogeneous composite packaging film, which is provided with a substrate layer, an ink layer, a barrier layer and a heat sealing layer in sequence from the outside to the inside, wherein 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 a barrier layer, which has better oxygen barrier properties, water vapor barrier properties, aroma retention and structural stability, enhances the bonding force with the heat sealing layer, and does not need to use an adhesive to bond the heat sealing layer. At the same time, it also has good heat insulation and reflective 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 longitudinal and transverse directions. 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.

[0011] The BOPP film of the present invention is made by using PP as a matrix and interacting with EVA and hyperbranched polymer modified POE. It has good transparency, excellent mechanical properties, and significantly improved temperature resistance and heat sealing properties, that is, temperature resistance>130°C, shrinkage rate<2% (120°C, 10 minutes); the three polyolefin materials are combined to make a film, so that the BOPP film has excellent oxygen barrier and water vapor barrier properties, can ensure barrier stability, and can maintain the quality stability of the product in the film. The addition of hyperbranched polymer modified POE makes the components of the BOPP film have excellent compatibility, and the crystallization performance of polyolefins will not be reduced due to the addition of hyperbranched polymers. On the contrary, the strength and flexibility of the BOPP film are improved, and the high temperature resistance, waterproofness, gas barrier and weather resistance of BOPP are significantly improved; the addition of EVA not only improves the water vapor barrier and oxygen barrier of the BOPP film, but also improves the impact resistance of the BOPP film, and ensures that the temperature resistance and chemical corrosion resistance of the BOPP film are excellent, extending the service life of the present invention.

[0012] Furthermore, the hyperbranched polymer modified POE is modified by using a terminal hydroxyl hyperbranched polyester, and the preparation method thereof comprises the following steps:

[0013] 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;

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

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

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

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

[0018] The added 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 prepared by reacting POE grafted with acrylic acid and terminal hydroxyl hyperbranched polyester. The method of the present invention is used to modify the terminal hydroxyl hyperbranched polyester to carry out POE, which 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 BOPP film, and is not easy to shrink and curl during the heat sealing process, thereby ensuring the flatness of the edge sealing of the formed product; the compatibility between PP and EVA is improved, and then the mechanical strength and impact resistance of the BOPP film are improved, so that after the heavy object is dropped, the packaging bag is not easy to break, thereby ensuring the use quality of the product and extending the service life of the product.

[0021] Furthermore, 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 %;

[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 the comprehensive properties such as mechanical properties, high barrier properties and high temperature resistance required by the present invention.

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

[0026] Furthermore, the PE composite film is composed of the following raw materials in parts by mass: 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 ethylene-vinyl acetate copolymer.

[0027] The PE composite film made of polyethylene compound, polyolefin elastomer, maleic anhydride grafted polyethylene and ethylene-vinyl acetate copolymer has excellent low temperature resistance, heat sealing and water resistance, further improving the oxygen barrier, water vapor barrier and fragrance retention of the present invention; it also has excellent adhesion or printability, and can make it possible to add no adhesive between the heat seal layer and the barrier layer, reducing costs and processing procedures. 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 improves the heat sealing, low temperature resistance and waterproofness of the PE composite film; the addition of ethylene-vinyl acetate copolymer improves the heat sealing, impact resistance, toughness and low temperature resistance of the PE composite film, and makes the PE composite film have better adhesion, while improving the gas barrier and waterproofness of the PE composite film.

[0028] Furthermore, 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;

[0029] The melt index of the ethylene-vinyl acetate copolymer at 190° C. and a load of 2.16 kg is 25 g / 10 min, and the VA content is 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-sealing layer. The three cooperate with each other to make the heat-sealing layer have better heat-sealing properties, mechanical strength and barrier properties, and improve the low-temperature resistance and puncture resistance of the heat-sealing layer, significantly extending the service life of the present invention. Selecting ethylene-vinyl acetate copolymer with appropriate parameters can ensure that the PE composite film has better heat-sealing properties and adhesion.

[0031] Furthermore, the thickness of the substrate layer (1) is 10-25 μm;

[0032] The thickness of the barrier layer (3) is 12-15 μm;

[0033] The thickness of the heat-sealing layer (4) is 30-60 μm.

[0034] It is worth noting that the thickness of functional layers such as the substrate layer and the heat-sealing layer can be designed according to different packaging materials. The layer thickness designed in the present invention only means that the required performance requirements can be achieved by using a film layer within this thickness range.

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

[0036] 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;

[0037] P2. After cooling the substrate layer to 30-35°C, perform corona treatment, and then print the ink layer on the corona side of the substrate layer. After printing, dry and cool to room temperature;

[0038] P3. A water-based polyurethane adhesive is applied to the aluminum-plated side surface of the VMBOPP film, and a composite layer of a substrate layer and an ink layer is pressed thereon, wherein the ink layer faces the VMBOPP film, and the pressing temperature is 60-80°C;

[0039] P4. Add the raw material of PE composite film into the casting machine, heat it to 135-145℃ to melt, then flow out through the flat head of the casting machine, press it to the composite layer composed of substrate layer, ink layer and VMBOPP film between two rollers in close contact to obtain a heat-sealing layer tightly attached to the VMBOPP film, press it at 60-80℃ for 0.5-1h, cool it to room temperature, and obtain an ultra-high barrier homogeneous composite packaging film.

[0040] Furthermore, the process of biaxial stretching in step P1 is: firstly stretching the film bubble longitudinally by 5 times at 130°C, then stretching it transversely by 8 times at 170°C, and finally heat-setting it at 180°C for 5-10s.

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

[0042] 1. The ultra-high barrier homogeneous composite packaging film provided by the present invention has a substrate layer of BOPP film, which is made of PP as a matrix, and is prepared by adding hyperbranched polymer modified POE and ethylene-vinyl acetate copolymer and other components to an appropriate multiple for longitudinal and transverse biaxial stretching. Its heat deformation temperature is increased from the original 124°C to above 140°C, and it has excellent high temperature resistance and heat sealing performance, and also has excellent mechanical strength, toughness, gas barrier and weather resistance. The BOPP film of the present invention has better heat sealing and thermal stability by designing suitable materials and adjusting suitable raw material ratios. At the same time, it also reduces the heat shrinkage rate of the BOPP film, so that the heat deformation temperature difference between it and the heat sealing layer material is large, so that the edge sealing effect is good when making packaging bags, the product yield is improved, and the cost is saved.

[0043] 2. The present invention designs the formula of PE composite materials and the proportion of raw materials, and adopts the PE composite film prepared by the casting process as the heat-sealing layer, which 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, ensures that the heat-sealing layer is not easily punctured, and makes it suitable for various liquid and powder packaging with barrier requirements.

[0044] 3. The difference in thermal deformation temperature between the substrate layer and the heat-sealing layer of the present invention is greater than 40°C, which significantly improves the heat-sealing process of the present invention, makes the heat-sealing process easy to control, has high sealing strength, and does not affect the comprehensive performance of the substrate layer.

[0045] 4. The composite packaging film of the present invention is composed of a substrate layer, an ink layer, a barrier layer and a heat-sealing layer. The polyolefin material in the raw materials accounts for more than 90%, is environmentally friendly and easily available, and the processing technology is simple and easy to control. The film layers have good bonding properties and are not easy to peel off. The film layers interact with each other, thereby ensuring that the present invention has ultra-high barrier properties, high fragrance retention properties, high heat sealing properties, excellent high and low temperature resistance, high wear resistance and corrosion resistance, which prolongs the service life of the coated composite film and broadens the application field of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic structural diagram of the high oxygen barrier and high fragrance preservation coating composite film of the present invention.

[0047] Figure symbols: 1. substrate layer; 2. ink layer; 3. barrier layer; 4. heat sealing layer. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

[0050] 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 and the die temperature is 220°C, and then the film is blown to form a film bubble, which is then cooled and then biaxially stretched, that is, the film bubble is first longitudinally stretched 5 times at 130°C, then transversely stretched 8 times at 170°C, and finally heat-set at 180°C for 5-10s to obtain a substrate layer 1. Preferably, the thickness of the substrate layer 1 is 10-25 μm.

[0051] Preferably, 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.

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

[0053] Preferably, the melt index of 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 %. In the embodiment of the present invention, preferably, EVA is selected from DuPont of the United States, and the model is EVA 660.

[0054] Preferably, the nucleating agent is an organic phosphate nucleating agent. In the embodiment of the present invention, preferably, the nucleating agent is selected from Aidico, model 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 modified by using a terminal hydroxyl hyperbranched polyester, and its preparation method comprises the following steps by weight:

[0057] S1. According to the mass proportion, 100 parts of POE, 2-4 parts of acrylic acid monomer, 1.5-3 parts of styrene monomer and 0.3-0.6 parts of initiator DCP are mixed evenly, and then placed in a twin-screw extruder for melt grafting reaction, extrusion granulation, extrusion temperature of 170-180 ° C, screw speed of 60r / min, to obtain POE-g-AA.

[0058] Preferably, POE is selected from ExxonMobil, model POE 3000.

[0059] S2. Add 5-8 parts of terminal hydroxyl hyperbranched polyester, 100 parts of POE-g-AA and 0.03-0.06 parts of tetrabutyl titanate into a reaction kettle by mass, then introduce nitrogen, raise the temperature to 170-180°C, stir and react for 2-3 hours, distill to remove water, cool naturally and evacuate for 5-10 minutes to obtain a hyperbranched polymer modified POE.

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

[0061] P2. After the substrate layer 1 is cooled to 30-35°C, it is subjected to corona treatment, cleaned, and subjected to antistatic treatment. Then, the ink layer 2 is printed on the corona surface of the substrate layer 1. After printing, it is dried and cooled to room temperature.

[0062] Preferably, the ink layer 2 is water-based ink; preferably, the water-based ink is PE water-based ink or acrylic water-based ink. In the embodiment of the present invention, preferably, the water-based ink is PE water-based ink, selected from Shenzhen Yamato Ink Technology, model 82 series.

[0063] P3. Apply a water-based polyurethane adhesive on the aluminum-plated side surface of the VMBOPP film, and press a composite layer of the substrate layer 1 and the ink layer 2 thereon, wherein the ink layer 2 faces the VMBOPP film. The pressing temperature is 60-80°C and the pressing time is 10-15s to obtain 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 Cailong Coating Packaging Materials Co., Ltd., and the thickness of the aluminum layer is 1.9Ω / □.

[0066] P4. Add the raw material of PE composite film into the casting machine, heat it to 135-145℃ to melt, then flow out through the flat head of the casting machine, press it between two closely contacted rollers to the composite layer composed of substrate layer 1, ink layer 2 and VMBOPP film, and obtain the heat sealing layer 4 which is closely attached to the VMBOPP film. Press it at 60-80℃ for 0.5-1h, and cool it to room temperature to obtain 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 weight: 30-50 parts of polyethylene compound, 10-20 parts of polyolefin elastomer (selected from ExxonMobil's POE 3000), 5-8 parts of maleic anhydride grafted polyethylene and 25-45 parts of ethylene-vinyl acetate copolymer.

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

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

[0071] The steps of preparing the super-barrier homogeneous composite packaging film into packaging bags are: cutting and forming the high-barrier and high-flavor-retaining coated composite film according to the set size, then making bags through heat sealing process, and then engraving laser easy-tear edges to obtain packaging bags for the required products. The heat sealing process conditions are: heat sealing temperature of 110-130℃, pressure of 3-6kg / cm 2 .

[0072] The ultra-barrier homogeneous composite packaging film of the present invention is described below with reference to specific embodiments.

[0073] Example 1 PP film in substrate layer 1

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

[0075] The preparation method of the hyperbranched polymer modified POE comprises the following steps by weight:

[0076] S1. According to the mass proportion, 100 parts of POE, 2 parts of acrylic acid monomer, 1.5 parts of styrene monomer and 0.3 parts of initiator DCP were mixed evenly, and then placed in a twin-screw extruder for melt grafting reaction, extrusion granulation, extrusion temperature of 170-180 ° C, screw speed of 60r / min, to obtain POE-g-AA.

[0077] S2. 5 parts of terminal hydroxyl hyperbranched polyester HyPer H20, 100 parts of POE-g-AA and 0.04 parts of tetrabutyl titanate were added into a reactor by mass, and then nitrogen was introduced. The temperature was raised to 170°C and stirred for reaction for 3 hours. Water was distilled off, and the reactor was naturally cooled and vacuumed to 0.9 MPa for 10 minutes to obtain a hyperbranched polymer modified POE.

[0078] The raw materials of the above PP film are mixed, and the mixture is melt-extruded and granulated in a twin-screw extruder, wherein the screw temperature is 200-210° C. and the die temperature is 220° C. to obtain PP particles.

[0079] The obtained PP particles were tested according to the standard of GB / T 1634-2019, and the heat deformation temperature was 142°C.

[0080] Example 2 PP film in substrate layer 1

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

[0082] The preparation method of the hyperbranched polymer modified POE comprises the following steps by weight:

[0083] S1. According to the mass proportion, 100 parts of POE, 4 parts of acrylic monomer, 3 parts of styrene monomer and 0.5 parts of initiator DCP were mixed evenly, and then placed in a twin-screw extruder for melt grafting reaction, extrusion granulation, extrusion temperature of 170-180 ° C, screw speed of 60r / min, to obtain POE-g-AA.

[0084] S2. By mass, 8 parts of terminal hydroxyl hyperbranched polyester HyPer H40, 100 parts of POE-g-AA and 0.06 parts of tetrabutyl titanate were added to a reactor, and then nitrogen was introduced. The temperature was raised to 180°C and stirred for reaction for 3 hours. Water was distilled off, and the reactor was naturally cooled and vacuumed to 1.0 MPa for 8 minutes to obtain a hyperbranched polymer modified POE.

[0085] The above PP film raw material was tested according to the method of Example 1. The heat deformation temperature of the PP film of Example 2 was 145°C.

[0086] Example 3 PP film in substrate layer 1

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

[0088] The preparation method of the hyperbranched polymer modified POE comprises the following steps by weight:

[0089] S1. According to the mass proportion, 100 parts of POE, 3 parts of acrylic monomer, 2 parts of styrene monomer and 0.4 parts of initiator DCP were mixed evenly, and then placed in a twin-screw extruder for melt grafting reaction, extrusion granulation, extrusion temperature of 170-180 ° C, screw speed of 60r / min, to obtain POE-g-AA.

[0090] S2. According to the mass proportions, 7 parts of terminal hydroxyl hyperbranched polyester HyPer H20, 100 parts of POE-g-AA and 0.05 parts of tetrabutyl titanate were added into the reactor, and then nitrogen was introduced. The temperature was raised to 180°C and stirred for reaction for 3 hours. The water was distilled off, and the reactor was naturally cooled and vacuumed to 1.0 MPa for 8 minutes to obtain a hyperbranched polymer modified POE.

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

[0092] Example 4 PP film in substrate layer 1

[0093] The raw materials, preparation process, etc. of the PP film of this embodiment are the same as those of Example 3. The difference is that the mass parts 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 parts of nucleating agent NA-21 and 0.2 parts of antioxidant TNP.

[0094] The above PP film raw material was tested according to the method of Example 1. The heat deformation 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 Comparative Example 1 are the same as those in Example 4, except that no hyperbranched polymer-modified POE is added in Comparative Example 1, and the amount of polypropylene added is 85 parts.

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

[0098] Comparative Example 2

[0099] The raw materials, preparation process, etc. of the PP film in Comparative Example 2 are the same as those in Example 4, except that no hyperbranched polymer-modified POE is added in Comparative Example 2, and 20 parts of a mixture of POE and hydroxyl hyperbranched polyester HyPerH20 in a mass ratio of 100:7 are added.

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

[0101] Comparative Example 3

[0102] The raw materials, preparation process, etc. of the PP film in Comparative Example 3 are the same as those in Example 4, except that the hydroxy hyperbranched polyester HyPer H20 in Comparative Example 3 is replaced by a terminal hydroxyl saturated polyester, and the terminal hydroxyl saturated polyester is selected from HK7805 of Hubei Xinyuhong.

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

[0104] Comparative Example 4

[0105] The raw materials, preparation process, etc. of the PP film in Comparative Example 4 are the same as those in Example 4, except that no ethylene-vinyl acetate copolymer is added in Comparative Example 4, and the amount of polypropylene added is 80 parts.

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

[0107] Example 5 PE composite film

[0108] The PE composite film of Example 5 is composed of the following raw materials in parts by weight: 42 parts of polyethylene compound, 18 parts of polyolefin elastomer, 7 parts of maleic anhydride grafted polyethylene and 33 parts of ethylene-vinyl acetate copolymer (EA28025). The polyethylene compound is a mixture of LDPE (N220), LLDPE (LL6201RQ) and metallocene polyethylene (5410G) in a mass ratio of 2:1:3.

[0109] The raw materials of the above PE composite film are mixed, and the mixture is melt-extruded and granulated in a twin-screw extruder, wherein the screw temperature is 160-180° C. and the die temperature is 190° C. to obtain PE particles.

[0110] The obtained PE particles were tested according to the standard of GB / T 1634-2019, and the thermal deformation temperature was found to be 85°C.

[0111] Comparative Example 5

[0112] The raw materials and proportions of the PE composite film in Comparative Example 5 are the same as those in Example 5, except that no polyolefin elastomer is added in Comparative Example 5, and the amount of the polyethylene composite added is 60 parts.

[0113] Comparative Example 6

[0114] The raw materials and proportions of the PE composite film in Comparative Example 6 are the same as those in Example 5, except that no ethylene-vinyl acetate copolymer is added in Comparative Example 6, and the amount of the polyethylene composite added 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, except that the polyethylene composite in this comparative example 7 is a mixture of low-density polyethylene, linear low-density polyethylene and metallocene polyethylene in a mass ratio of 5:1:2.

[0117] Comparative Example 8

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

[0119] Application Example 1

[0120] The substrate layer 1, the ink layer 2, the barrier layer 3 and the heat-sealing layer 4 are sequentially arranged from the outside to the inside to form an ultra-high barrier homogeneous composite packaging film, and the specific preparation process thereof is as follows:

[0121] P1. The raw materials of the PP film in Example 1 were mixed to obtain a mixture, which was melt-extruded through a twin-screw extruder, wherein the screw temperature was 200-210°C and the die temperature was 220°C, and then the film was blown to form a bubble, which was then cooled, and then the bubble was longitudinally stretched 5 times at 130°C, then transversely stretched 8 times at 170°C, and finally heat-set at 180°C for 8s to obtain a substrate layer 1. The thickness of the substrate layer 1 was about 15 μm.

[0122] P2. Cool the substrate layer 1 to 30°C and then 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 destaticize the substrate layer 1, and then print PE water-based ink on the corona-treated side of the substrate layer 1. After printing, dry and cool to room temperature to obtain ink layer 2.

[0123] P3. A water-based polyurethane adhesive (Covestro U54 from Germany) was coated on the aluminum-plated side surface of the VMBOPP film (selected from Foshan Cailong Coating Packaging Materials Co., Ltd.), and a composite layer of the substrate layer and the ink layer 2 was pressed thereon, wherein the ink layer 2 faced the VMBOPP film. The pressing temperature was 70°C and the pressing time was 12s.

[0124] P4. The raw material of the PE composite film in Example 5 is added to a casting machine, heated to 140°C to melt, and then flows out through a flat die head, and is pressed between two closely contacting rollers to a composite layer consisting of a substrate layer 1, an ink layer 2, and a VMBOPP film to obtain a heat-sealing layer 4 that is closely attached to the VMBOPP film, pressed at 70°C for 30 minutes, and cooled to room temperature to obtain an ultra-high barrier homogeneous composite packaging film. The thickness of the heat-sealing layer 4 is 40 μm.

[0125] Application Example 2

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

[0127] Application Example 3

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

[0129] Application Example 4

[0130] The structure and preparation process of the super-barrier homogeneous composite packaging film of Application Example 4 are the same as those in Application Example 1, and specific reference is made to Application Example 1. The difference is that the raw material of the PP film is prepared according to Example 4.

[0131] Application Comparative Example 1

[0132] The structure and preparation process of the super-barrier homogeneous composite packaging film of the comparative example 1 of this application are the same as those in the application example 4. Please refer to the application example 4 for details. The difference is that the raw materials of the PP film are prepared according to the comparative example 1.

[0133] Application Comparative Example 2

[0134] The structure and preparation process of the super-barrier homogeneous composite packaging film of the comparative example 2 of this application are the same as those in the application example 4. Please refer to the application example 4 for details. The difference is that the raw materials of the PP film are prepared according to the comparative example 2.

[0135] Application Comparative Example 3

[0136] The structure and preparation process of the super-barrier homogeneous composite packaging film of the comparative example 3 of this application are the same as those in the application example 4. Please refer to the application example 4 for details. The difference is that the raw materials of the PP film are prepared according to the comparative example 3.

[0137] Application Comparative Example 4

[0138] The structure and preparation process of the super-barrier homogeneous composite packaging film of the comparative example 4 of this application are the same as those in the application example 4, and specific reference is made to the application example 4, except that the raw materials of the PP film are prepared according to the 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. Please refer to Application Example 4 for details. The difference is that the raw materials of the PE composite film are prepared 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. Please refer to Application Example 4 for details. The difference is that the raw materials of the PE composite film are prepared 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. Please refer to Application Example 4 for details. The difference is that the raw materials of the PE composite film are prepared according to Comparative Example 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. Please refer to Application Example 4 for details. The difference is that the raw materials of the PE composite film are prepared according to Comparative Example 8.

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

[0148] The detection method is as follows:

[0149] Oxygen permeability: tested according to 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 GB / T 1037-2021 Test method for water vapor transmission of plastic film and sheet;

[0151] Interlayer peeling strength (peeling strength between the heat sealing layer and the composite layer consisting of the substrate layer, the polyvinyl alcohol composite film and the ink layer): tested according to the standard of GB / T 8808-88 Peeling test method for soft composite plastic materials;

[0152] Low temperature resistance: According to the standard of GB / T 1040.2-2022 Determination of tensile properties of plastics, 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 high barrier and high fragrance protection coated composite films

[0154]

[0155]

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

[0157] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, 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, they should be considered to be within the scope of this specification.

[0158] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, 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, It is 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 is obtained by stretching a PP film in both longitudinal and transverse directions. 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.

2. The ultra-high barrier homogeneous composite packaging film according to claim 1, It is characterized in that The hyperbranched polymer modified POE adopts terminal hydroxyl hyperbranched polyester to modify POE, and its preparation method 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. Add hyperbranched polymer, POE-g-AA and an appropriate amount of tetrabutyl titanate into a reaction kettle, then introduce nitrogen, raise the temperature to 170-180°C, stir and react for 2-3 hours, distill to remove water, cool naturally and evacuate for 5-10 minutes to obtain a hyperbranched polymer modified POE.

3. The ultra-high barrier homogeneous composite packaging film according to claim 2, It is 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 added amount of the hyperbranched polymer 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.

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

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

6. The ultra-high barrier homogeneous composite packaging film according to claim 1, It is characterized in that The PE composite film is composed of the following raw materials in parts by mass: 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 ethylene-vinyl acetate copolymer.

7. The ultra-high barrier homogeneous composite packaging film according to claim 6, It is characterized in that The polyethylene compound is formed by mixing low-density polyethylene, linear low-density polyethylene and metallocene polyethylene in a mass ratio of 2:1:3; The melt index of the ethylene-vinyl acetate copolymer at 190° C. and a load of 2.16 kg is 25 g / 10 min, and the VA content is 28 wt %.

8. The ultra-high barrier homogeneous composite packaging film according to claim 1, It is 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.

9. A process for preparing the ultra-high barrier homogeneous composite packaging film according to any one of claims 1 to 8, It is 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.

10. The process for preparing the ultra-high barrier homogeneous composite packaging film according to claim 9, It is 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.

Images