Polyethylene environment-friendly packaging material as well as preparation method and application thereof

Abstract

The invention relates to a polyethylene environment-friendly packaging material as well as a preparation method and application thereof. The polyethylene environment-friendly packaging material comprises a printing layer, a barrier coating, a middle layer and a heat sealing layer which are arranged in sequence. The polyethylene environment-friendly material is a composite packaging material with an all-polyethylene structure, well meets the standard requirement of a single recyclable material, and is green and economical. Meanwhile, the film has excellent moisture and oxygen resistance, heat sealing strength, peel strength, sealing capacity and anti-falling performance, and can well meet the actual application requirements of customers.

Description

Technical Field

[0001] The present invention relates to the technical field of packaging materials, and in particular to an environmentally friendly polyethylene packaging material and a preparation method and application thereof. Background Art

[0002] Most of the existing soft packaging materials on the market are composite film structures composed of PET, PA, AL, PE and other materials. The composite film structure can overcome the shortcomings of single-layer films and has been widely used in packaging materials. However, due to the large variety of materials and complex composition, it is not conducive to the convenience of recycling. In addition, the existing composite film structure has poor moisture and oxygen barrier properties. In order to improve its barrier properties, an aluminum foil layer is usually set. However, the composite material of aluminum foil and plastic film needs to be specially separated and processed when recycled, which makes recycling difficult, not only causing waste of resources, but also polluting the environment.

[0003] The sales volume of pet food is increasing as people's living standards improve, and higher requirements are placed on the barrier properties, heat sealing strength, peel strength, and drop resistance of packaging materials.

[0004] CN208593143U discloses an environmentally friendly pet food composite packaging film, which is composed of a printing layer, an anti-ultraviolet aluminum powder particle layer, an antibacterial layer, a polyester aluminum-plated film layer and a heat-sealed CPP film layer arranged from top to bottom, and has the advantages of good appearance, good barrier performance and preservation effect, and no stimulation to pets, but it cannot be well recycled and reused due to the large variety of materials and the presence of a polyester aluminum-plated film layer. CN118752876A discloses a high-barrier food packaging material and a preparation process thereof, the high-barrier food packaging material includes a barrier layer, a core layer and a secondary barrier layer, and has stable and efficient barrier, antibacterial, mechanical and antioxidant properties, but the oxygen and moisture barrier properties of the high-barrier food packaging material are still poor.

[0005] Therefore, it is of great significance to develop a high-barrier environmentally friendly packaging material with good drop performance and heat sealing strength and peel strength that meet the requirements. Summary of the invention

[0006] In order to solve the above technical problems, the present technology provides a polyethylene environmentally friendly packaging material and its preparation method and application. The polyethylene (PE) environmentally friendly packaging material is a full polyethylene structure, which meets the standard requirements of a single recyclable material; and has excellent moisture and oxygen barrier properties, good drop performance, and also has high heat sealing strength, peel strength and sealing ability, and can be well applied to pet food packaging bags below 20kg.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides an environmentally friendly polyethylene packaging material, which includes a printing layer, a barrier coating layer, an intermediate layer and a heat-sealing layer arranged in sequence.

[0009] The present invention obtains a composite packaging material with a full polyethylene structure having a PE content of more than 95% by sequentially compounding a printing layer, a barrier coating, an intermediate layer and a heat-sealing layer, which satisfies the standard requirements of a single recyclable material and is green and economical. At the same time, it has excellent moisture and oxygen barrier properties, heat sealing strength, peel strength, sealing ability and anti-drop performance, and can well meet the actual application needs of customers.

[0010] Preferably, the heat sealing layer is a three-layer co-extruded PE layer.

[0011] Preferably, the three-layer co-extruded PE layer comprises a composite layer, a core layer and an inner layer which are arranged in sequence.

[0012] Preferably, the raw materials for preparing the composite layer include metallocene polyethylene (MPE) and low-density polyethylene (LDPE).

[0013] Preferably, the metallocene polyethylene has a melt index of 0.5-2 g / 10 min (for example, 0.5 g / 10 min, 0.8 g / 10 min, 1.0 g / 10 min, 1.2 g / 10 min, 1.4 g / 10 min, 1.6 g / 10 min, 1.8 g / 10 min or 2 g / 10 min, etc.) at 190 ° C / 2.16 kg, and a density of 0.91-0.94 g / cm 3 (For example, it can be 0.91g / cm 3 、0.915g / cm 3 , 0.92g / cm 3 、0.925g / cm 3 、0.93g / cm 3 , 0.935g / cm 3 or 0.94g / cm 3 wait).

[0014] Preferably, the low-density polyethylene has a melt index of 0.5-4 g / 10 min (for example, 0.5 g / 10 min, 1.0 g / 10 min, 1.5 g / 10 min, 2 g / 10 min, 2.5 g / 10 min, 3 g / 10 min, 3.5 g / 10 min or 4 g / 10 min, etc.) at 190 ° C / 2.16 kg, and a density of 0.92-0.94 g / cm 3 (For example, it can be 0.92g / cm 3 , 0.922g / cm 3 , 0.924g / cm3 , 0.926g / cm 3 , 0.928g / cm 3 , 0.930g / cm 3 , 0.932g / cm 3 , 0.934g / cm 3 , 0.936g / cm 3 、0.938g / cm 3 or 0.94g / cm 3 wait).

[0015] Preferably, the raw materials for preparing the core layer include special high-density polyethylene (HDPE) and metallocene polyethylene (MPE);

[0016] Preferably, the special high-density polyethylene has a melt index of 0.5-2 g / 10 min (for example, 0.5 g / 10 min, 0.8 g / 10 min, 1.0 g / 10 min, 1.2 g / 10 min, 1.4 g / 10 min, 1.6 g / 10 min, 1.8 g / 10 min or 2 g / 10 min, etc.) at 190 ° C / 2.16 kg, and a density of 0.96-0.97 g / cm 3 (For example, it can be 0.96g / cm 3 , 0.961g / cm 3 , 0.962g / cm 3 、0.963g / cm 3 , 0.964g / cm 3 , 0.965g / cm 3 、0.966g / cm 3 , 0.967g / cm 3 、0.968g / cm 3 、0.969g / cm 3 or 0.97g / cm 3 wait).

[0017] Preferably, the raw materials for preparing the inner layer include low-temperature metallocene polyethylene (low-temperature MPE) and metallocene polyethylene (MPE).

[0018] Preferably, the low temperature metallocene polyethylene has a melt index of 0.5-8 g / 10 min (for example, 0.5 g / 10 min, 1.0 g / 10 min, 2 g / 10 min, 3 g / 10 min, 4 g / 10 min, 5 g / 10 min, 6 g / 10 min, 7 g / 10 min or 8 g / 10 min, etc.) at 190 ° C / 2.16 kg, and a density of 0.90-0.91 g / cm 3(For example, it can be 0.90g / cm 3 , 0.901g / cm 3 , 0.902g / cm 3 , 0.903g / cm 3 , 0.904g / cm 3 , 0.905g / cm 3 , 0.906g / cm 3 , 0.907g / cm 3 , 0.908g / cm 3 , 0.909g / cm 3 or 0.91g / cm 3 wait).

[0019] Preferably, the raw materials for preparing the composite layer further include a fluorine-free processing aid.

[0020] Preferably, based on the total mass of the raw materials for preparing the composite layer as 100%, the content of the metallocene polyethylene is 82-89% (for example, it can be 82%, 83%, 84%, 85%, 86%, 87%, 88% or 89%, etc.), the content of the low-density polyethylene is 10-15% (for example, it can be 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5% or 15%, etc.), and the content of the fluorine-free processing aid is 1-3% (for example, it can be 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8% or 3%, etc.).

[0021] Preferably, based on the total mass of the raw materials for preparing the core layer as 100%, the content of the special high-density polyethylene is 50-80% (for example, it can be 50%, 55%, 60%, 65%, 70%, 75% or 80%, etc.), and the content of the metallocene polyethylene is 20-50% (for example, it can be 20%, 25%, 30%, 35%, 40%, 45% or 50%, etc.).

[0022] In the present invention, when a specific content of raw materials is selected for the core layer, the toughness and moisture barrier properties of the obtained polyethylene environmentally friendly packaging material can achieve a good balance. When the content of special high-density polyethylene is higher than 80%, the anti-drop performance of the packaging material prepared therefrom is relatively poor; when the content of special high-density polyethylene is lower than 50%, the moisture barrier properties of the packaging material prepared therefrom will be reduced.

[0023] Preferably, the raw materials for preparing the inner layer further include an opening agent and a fluorine-free processing aid.

[0024] Preferably, based on the total mass of the raw materials for preparing the inner layer as 100%, the content of the low-temperature metallocene polyethylene is 50-83% (for example, it can be 50%, 55%, 60%, 65%, 70%, 75%, 80% or 83%, etc.), the content of the metallocene polyethylene is 15-45% (for example, it can be 15%, 20%, 25%, 30%, 35%, 40% or 45%, etc.), the content of the opening agent is 1-2% (for example, it can be 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9% or 2%, etc.), and the content of the fluorine-free processing aid is 1-3% (for example, it can be 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8% or 3%, etc.).

[0025] The heat-sealing layer in the present invention provides the packaging material with a three-layer co-extruded PE layer structure with good moisture barrier properties, and the composite layer and the extruded layer (PE layer) have high peeling strength; the core layer uses special high-density polyethylene to provide the packaging material with good moisture barrier properties; the low-temperature metallocene and metallocene combination of the inner layer have high heat-sealing strength, so that the packaging material has excellent pressure resistance and drop resistance.

[0026] Preferably, the thickness of the heat-sealing layer is 70-120 μm, for example, it can be 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm or 120 μm, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the said range.

[0027] Preferably, the thickness ratio of the composite layer, the core layer and the inner layer is 1:(1-3):1, wherein (1-3) can be 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8 or 3, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0028] In the present invention, when the thickness ratio of the composite layer, the core layer and the inner layer is 1:(1-3):1, the obtained polyethylene environmentally friendly packaging material can have excellent moisture barrier properties and anti-drop properties. When the thickness ratio of the core layer is too low, the moisture barrier properties of the prepared packaging material will be reduced; when the thickness ratio of the core layer is too high, the anti-drop properties of the prepared packaging material are relatively poor.

[0029] Preferably, the printing layer is a biaxially oriented polyethylene (BOPE) layer.

[0030] For example, the printing layer of the present invention may be pattern-printed by a gravure printing machine.

[0031] Preferably, the BOPE layer is subjected to single-sided corona treatment.

[0032] Preferably, the surface density of the printed layer is 0.94-0.96 g / cm 3 , for example, it can be 0.94 g / cm 3 , 0.942g / cm 3 , 0.942g / cm 3 , 0.946g / cm 3 , 0.948g / cm 3 , 0.95g / cm 3 , 0.952g / cm 3 , 0.954g / cm 3 、0.956g / cm 3 , 0.958g / cm 3 or 0.96g / cm 3 , as well as specific point values ​​between the above point values, due to space limitations and for the sake of brevity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0033] Preferably, the thickness of the printed layer is 20-40 μm, for example, it can be 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, 30 μm, 32 μm, 34 μm, 36 μm, 38 μm or 40 μm, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0034] Preferably, the barrier coating is a modified polyvinyl alcohol (PVOH) coating.

[0035] The present invention uses the modified PVOH coating as the barrier coating, which can provide the polyethylene environmentally friendly packaging material with excellent oxygen barrier performance and certain water resistance to prevent the oxygen barrier performance from being drastically reduced under high humidity conditions.

[0036] Preferably, the thickness of the barrier coating is 1-3 μm, for example, it may be 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm or 3 μm, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0037] Preferably, the middle layer is a BOPE layer.

[0038] Preferably, the BOPE layer is subjected to double-sided corona treatment.

[0039] Preferably, the surface density of the intermediate layer is 0.92-0.94 g / cm 3 , for example, it can be 0.92 g / cm 3 , 0.922g / cm 3 , 0.924g / cm 3 , 0.926g / cm 3 , 0.928g / cm 3 、0.93g / cm 3 , 0.932g / cm 3 , 0.934g / cm 3 , 0.936g / cm 3 、0.938g / cm 3 or 0.94g / cm 3 , as well as specific point values ​​between the above point values, due to space limitations and for the sake of brevity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0040] Preferably, the thickness of the intermediate layer is 20-40 μm, for example, it can be 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, 30 μm, 32 μm, 34 μm, 36 μm, 38 μm or 40 μm, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0041] Preferably, a glue layer is further provided between the barrier coating and the intermediate layer.

[0042] Preferably, the glue layer is a solvent-free glue layer.

[0043] Preferably, the solvent-free glue layer comprises solvent-free polyurethane glue.

[0044] Preferably, the amount of glue applied to the solvent-free glue layer is 1-2 g / m 2 , for example, 1g / m 2 , 1.1g / m 2 , 1.2g / m 2 , 1.3g / m 2 , 1.4g / m 2 , 1.5g / m 2 , 1.6g / m 2 , 1.7g / m 2 , 1.8g / m 2 , 1.9g / m 2 or 2g / m 2 , as well as specific point values ​​between the above point values, due to space limitations and for the sake of brevity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0045] Preferably, an extrusion layer is further provided between the intermediate layer and the heat-sealing layer.

[0046] Preferably, the extruded layer is a PE layer, and the PE layer is laminated between the middle layer BOPE and the heat-sealing layer PE by an extrusion laminating machine to form a structure of middle layer BOPE / extruded layer PE / heat-sealing layer PE.

[0047] In the present invention, the extruded PE layer connects the middle BOPE layer and the heat-sealing PE layer, providing the packaging material with higher peeling strength and sealing strength, and can meet the drop requirements of the pet food packaging bag.

[0048] Preferably, the thickness of the extruded layer is 20-25 μm, for example, it can be 20 μm, 20.5 μm, 21 μm, 21.5 μm, 22 μm, 22.5 μm, 23 μm, 23.5 μm, 24 μm, 24.5 μm or 25 μm, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0049] In the present invention, when the thickness of the extruded layer is 20-25 μm, the obtained polyethylene environmentally friendly packaging material has higher peeling strength and good anti-drop performance. When the thickness is too low, the peeling strength and anti-drop performance will be reduced.

[0050] In a second aspect, the present invention provides a method for preparing the polyethylene environmentally friendly packaging material as described in the first aspect, the preparation method comprising the following steps:

[0051] (1) coating a barrier coating on one side of the printing layer to obtain a printing layer / barrier coating;

[0052] (2) melt-extrude the raw materials for preparing the heat-sealing layer through a three-layer co-extrusion process, cool and shape, and perform corona treatment on the composite layer to obtain the heat-sealing layer;

[0053] The steps (1) and (2) are performed in no particular order;

[0054] (3) Compounding the intermediate layer and the heat-sealing layer to obtain a first composite layer;

[0055] (4) Compounding the printed layer / barrier coating of step (1) and the first composite layer of step (3), and aging them to obtain the polyethylene environmentally friendly packaging material.

[0056] Preferably, the three-layer co-extrusion process described in step (2) is carried out in a three-layer co-extrusion blown film equipment.

[0057] Preferably, the temperature of the melt coextrusion in step (2) is 160-250°C, for example, it can be 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C or 250°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the said range.

[0058] Preferably, the raw materials for preparing each layer of the heat sealing layer are added to a three-layer co-extrusion film blowing device, melted and plasticized at 160-250°C, extruded through a die, cooled and shaped, and the composite layer is corona treated and wound into a film to obtain the heat sealing layer.

[0059] Preferably, the intermediate layer and the heat-sealing layer in step (3) are compounded by extrusion to obtain an intermediate layer / extruded layer / heat-sealing layer, i.e., a first composite layer.

[0060] Preferably, the extrusion layer is carried out in an extrusion device.

[0061] Preferably, the production temperature of the extruded layer is 300-330°C, for example, it can be 300°C, 305°C, 310°C, 315°C, 320°C, 325°C or 330°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0062] Preferably, in step (4), the printing layer / barrier coating and the first composite layer are composited via a glue layer.

[0063] Preferably, the aging temperature in step (4) is 30-50°C, for example, it can be 30°C, 32°C, 34°C, 36°C, 38°C, 40°C, 42°C, 44°C, 46°C, 48°C or 50°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the said range.

[0064] Preferably, the aging time in step (4) is 48-72 h, for example, it can be 48 h, 50 h, 53 h, 55 h, 58 h, 60 h, 62 h, 65 h, 68 h, 70 h or 72 h, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0065] Exemplarily, the method for preparing the polyethylene environmentally friendly packaging material in the present invention specifically comprises the following steps:

[0066] (1) printing a pattern by a gravure printing machine to obtain a printing layer, and coating a barrier coating on one side of the printing layer on a dry laminating machine to obtain a printing layer / barrier coating;

[0067] (2) melt co-extruding the raw materials for preparing the heat sealing layer through a three-layer co-extrusion process, cooling and shaping, and performing corona treatment on the composite layer to obtain the heat sealing layer; wherein the temperature of the melt co-extrusion is 160-250° C.;

[0068] The steps (1) and (2) are performed in no particular order;

[0069] (3) The middle layer is placed on the first unwinding and the heat sealing layer is placed on the second unwinding. At 300-330° C., a PE film is laminated between the middle layer and the heat sealing layer by an extrusion laminating machine to obtain a structure of middle layer / extrusion laminating layer / heat sealing layer, i.e., the first composite layer.

[0070] (4) Compounding the printed layer / barrier coating of step (1) and the first composite layer of step (3) using solvent-free polyurethane glue, and aging at 30-50° C. for 48-72 hours to obtain the polyethylene environmentally friendly packaging material.

[0071] The polyethylene environmentally friendly packaging material prepared by the specific preparation method of the present invention has a structure of printed layer BOPE / barrier coating / glue layer / intermediate layer BOPE / extruded layer PE / heat-sealing layer PE, and the content of PE in the structure is more than 95%, which well meets the standard requirements of a single recyclable material.

[0072] In a third aspect, the present invention provides a use of the environmentally friendly polyethylene packaging material as described in the first aspect in a pet food packaging bag.

[0073] The polyethylene environmentally friendly packaging material with a full PE structure provided by the present invention is formed and bagged on a bag making machine to obtain a pet packaging bag with a full PE structure, which can be well recycled, is green and economical, and also has excellent moisture and oxygen barrier properties, anti-drop performance and sealing ability, peel strength, and heat sealing strength.

[0074] Compared with the prior art, the present invention has at least the following beneficial effects:

[0075] The polyethylene environmentally friendly packaging material of the present invention comprises a printing layer, a barrier coating, an intermediate layer and a heat-sealing layer arranged in sequence, and obtains a composite packaging material with a full polyethylene structure, and its PE content is greater than 95%, which well meets the standard requirements of a single recyclable material and is green and economical. At the same time, the polyethylene environmentally friendly packaging material of the present invention has excellent moisture and oxygen barrier properties, and its oxygen permeability (0.1Mpa, 23°C, 0%RH) is ≤1cm 3 / (m 2 ·24h), water vapor transmission rate (38℃, 90%RH)≤1g / (m 2·24h), and its heat sealing strength is ≥50N / 15mm, the peeling strength of each layer is ≥3N / 15mm, the sealing capacity is 60kPa / 60s without leakage, and the bag will not break after falling 3 times at 1.5m, which can well meet the actual application needs of customers. DETAILED DESCRIPTION

[0076] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0077] Unless otherwise specified, the raw materials used in the examples and comparative examples are commercially available. Information on some of the raw materials is as follows:

[0078] Printing layer BOPE: purchased from Jintian New Materials, model BOPE-HR;

[0079] Barrier coating: purchased from Shanghai Ruoyi New Materials, model H1909;

[0080] Glue layer: solvent-free polyurethane glue, purchased from Keyi, model SF7660 / CA7920;

[0081] Middle layer BOPE: purchased from Jintian New Materials, model BOPE-DT;

[0082] Extruded layer PE: The resin was purchased from Hanwha Chemical, with the brand name LD 955;

[0083] Metallocene polyethylene for heat sealing layer: purchased from Dow Chemical, brand 5400G;

[0084] Low-density polyethylene for heat-sealing layer: purchased from Yangzi-BASF, brand 2420H;

[0085] Special high-density polyethylene: purchased from Dow Chemical, brand name AT 6900;

[0086] Low temperature metallocene polyethylene: purchased from Dow Chemical, brand 1881G;

[0087] Antiblocking agent: purchased from LyondellBasell, brand F15;

[0088] Fluorine-free processing agent: purchased from LyondellBasell, brand AMF 7105.

[0089] Example 1

[0090] The present embodiment provides an environmentally friendly polyethylene packaging material, which includes a printing layer, a barrier coating, a solvent-free glue layer, an intermediate layer, an extrusion layer and a heat-sealing layer arranged in sequence from bottom to top.

[0091] The printing layer is a BOPE layer with a thickness of 30 μm and subjected to single-sided corona treatment;

[0092] The barrier coating is a modified PVOH coating with a thickness of 2 μm;

[0093] The glue layer has a glue amount of 1.5g / m 2 Solvent-free polyurethane glue;

[0094] The middle layer is a BOPE layer with a thickness of 30 μm and subjected to double-sided corona treatment;

[0095] The extruded layer is a PE layer with a thickness of 23 μm;

[0096] The heat-sealing layer is a three-layer co-extruded PE layer with a thickness of 95 μm, and the three-layer co-extruded PE layer consists of a composite layer, a core layer and an inner layer with a thickness of 1:3:1 arranged in sequence from bottom to top, wherein the components and contents of each layer are shown in Table 1.

[0097] Table 1

[0098]

[0099] The method for preparing the polyethylene environmentally friendly packaging material comprises the following steps:

[0100] (1) printing a pattern by a gravure printing machine to obtain a printing layer, and coating a barrier coating on one side of the printing layer on a dry laminating machine to obtain a printing layer / barrier coating;

[0101] (2) melt co-extruding the raw materials for preparing the heat sealing layer through a three-layer co-extrusion process, cooling and shaping, and performing corona treatment on the composite layer to obtain the heat sealing layer; wherein the temperature of the melt co-extrusion is 200° C.;

[0102] The steps (1) and (2) are performed in no particular order;

[0103] (3) placing the middle layer BOPE on the first unwinding roll and the heat sealing layer on the second unwinding roll, and laminating PE between the middle layer BOPE and the heat sealing layer PE by an extrusion laminating machine at 330° C. to obtain a structure of middle layer BOPE / extrusion laminating layer PE / heat sealing layer PE, i.e., the first composite layer;

[0104] (4) The printed layer / barrier coating of step (1) and the first composite layer of step (3) are composited using solvent-free polyurethane glue, and aged at 40° C. for 60 hours to obtain the polyethylene environmentally friendly packaging material.

[0105] Example 2

[0106] The present embodiment provides an environmentally friendly polyethylene packaging material, which includes a printing layer, a barrier coating, a solvent-free glue layer, an intermediate layer, an extrusion layer and a heat-sealing layer arranged in sequence from bottom to top.

[0107] The printing layer is a BOPE layer with a thickness of 20 μm and subjected to single-sided corona treatment;

[0108] The barrier coating is a modified PVOH coating having a thickness of 1 μm;

[0109] The glue layer has a glue amount of 1g / m 2 Solvent-free polyurethane glue;

[0110] The middle layer is a BOPE layer with a thickness of 20 μm and subjected to double-sided corona treatment;

[0111] The extruded layer is a PE layer with a thickness of 20 μm;

[0112] The heat-sealing layer is a three-layer co-extruded PE layer with a thickness of 70 μm, and the three-layer co-extruded PE layer consists of a composite layer, a core layer and an inner layer with a thickness of 1:1:1 arranged in sequence from bottom to top, wherein the components and contents of each layer are shown in Table 2.

[0113] Table 2

[0114]

[0115]

[0116] The method for preparing the polyethylene environmentally friendly packaging material comprises the following steps:

[0117] (1) printing a pattern by a gravure printing machine to obtain a printing layer, and coating a barrier coating on one side of the printing layer on a dry laminating machine to obtain a printing layer / barrier coating;

[0118] (2) melt co-extruding the raw materials for preparing the heat sealing layer through a three-layer co-extrusion process, cooling and shaping, and performing corona treatment on the composite layer to obtain the heat sealing layer; wherein the temperature of the melt co-extrusion is 190° C.;

[0119] The steps (1) and (2) are performed in no particular order;

[0120] (3) placing the middle layer BOPE on the first unwinding roll and the heat sealing layer on the second unwinding roll, and laminating PE between the middle layer BOPE and the heat sealing layer PE by an extrusion laminating machine at 320° C. to obtain a structure of middle layer BOPE / extrusion laminating layer PE / heat sealing layer PE, i.e., the first composite layer;

[0121] (4) The printed layer / barrier coating of step (1) and the first composite layer of step (3) are composited using solvent-free polyurethane glue, and aged at 30° C. for 48 hours to obtain the polyethylene environmentally friendly packaging material.

[0122] Example 3

[0123] The present embodiment provides an environmentally friendly polyethylene packaging material, which includes a printing layer, a barrier coating, a solvent-free glue layer, an intermediate layer, an extrusion layer and a heat-sealing layer arranged in sequence from bottom to top.

[0124] The printing layer is a BOPE layer with a thickness of 40 μm and subjected to single-sided corona treatment;

[0125] The barrier coating is a modified PVOH coating with a thickness of 3 μm;

[0126] The glue layer has a glue amount of 2g / m 2 Solvent-free polyurethane glue;

[0127] The middle layer is a BOPE layer with a thickness of 40 μm and subjected to double-sided corona treatment;

[0128] The extruded layer is a PE layer with a thickness of 25 μm;

[0129] The heat-sealing layer is a three-layer co-extruded PE layer with a thickness of 120 μm, and the three-layer co-extruded PE layer consists of a composite layer, a core layer and an inner layer with a thickness of 1:2:1 arranged in sequence from bottom to top, wherein the components and contents of each layer are shown in Table 3.

[0130] Table 3

[0131]

[0132] The method for preparing the polyethylene environmentally friendly packaging material comprises the following steps:

[0133] (1) printing a pattern by a gravure printing machine to obtain a printing layer, and coating a barrier coating on one side of the printing layer on a dry laminating machine to obtain a printing layer / barrier coating;

[0134] (2) melt-coextruding the raw materials for preparing the heat-sealing layer through a three-layer coextrusion process, cooling and shaping, and performing corona treatment on the composite layer to obtain the heat-sealing layer; wherein the temperature of the melt-coextrusion is 180° C.;

[0135] The steps (1) and (2) are performed in no particular order;

[0136] (3) placing the middle layer BOPE on the first unwinding and the heat sealing layer on the second unwinding, and laminating PE between the middle layer BOPE and the heat sealing layer PE by an extrusion laminating machine at 300° C. to obtain a structure of middle layer BOPE / extrusion laminating layer PE / heat sealing layer PE, i.e., the first composite layer;

[0137] (4) The printed layer / barrier coating of step (1) and the first composite layer of step (3) are composited using solvent-free polyurethane glue, and aged at 50° C. for 72 hours to obtain the polyethylene environmentally friendly packaging material.

[0138] Example 4

[0139] This embodiment provides a polyethylene environmentally friendly packaging material, which differs from Example 1 in that the raw materials for preparing the core layer in the structure of the heat-sealing layer are 50% special high-density polyethylene and 50% metallocene polyethylene, and the other structures, parameters and preparation methods are the same as those in Example 1.

[0140] Example 5

[0141] This embodiment provides a polyethylene environmentally friendly packaging material, which differs from Example 1 in that the raw materials for preparing the core layer in the structure of the heat-sealing layer are 80% special high-density polyethylene and 20% metallocene polyethylene, and the other structures, parameters and preparation methods are the same as those in Example 1.

[0142] Example 6

[0143] This embodiment provides a polyethylene environmentally friendly packaging material, which differs from Example 1 in that the raw materials for preparing the core layer in the structure of the heat-sealing layer are 85% special high-density polyethylene and 15% metallocene polyethylene, and the other structures, parameters and preparation methods are the same as those in Example 1.

[0144] Example 7

[0145] This embodiment provides a polyethylene environmentally friendly packaging material, which differs from Example 1 in that the raw materials for preparing the core layer in the structure of the heat-sealing layer are 45% special high-density polyethylene and 55% metallocene polyethylene, and the other structures, parameters and preparation methods are the same as those in Example 1.

[0146] Example 8

[0147] This embodiment provides a polyethylene environmentally friendly packaging material, which differs from Example 1 in that the thickness ratio of the composite layer, the core layer and the inner layer in the three-layer co-extruded PE layer is adjusted from 1:3:1 to 1:3.5:1, and the other structures, parameters and preparation methods are the same as those in Example 1.

[0148] Example 9

[0149] This embodiment provides a polyethylene environmentally friendly packaging material, which differs from Example 1 in that the thickness ratio of the composite layer, the core layer and the inner layer in the three-layer co-extruded PE layer is adjusted from 1:3:1 to 1:1:1, and other structures, parameters and preparation methods are the same as those in Example 1.

[0150] Example 10

[0151] This embodiment provides a polyethylene environmentally friendly packaging material, which differs from Example 1 in that the thickness ratio of the composite layer, the core layer and the inner layer in the three-layer co-extruded PE layer is adjusted from 1:3:1 to 1:0.5:1, and other structures, parameters and preparation methods are the same as those in Example 1.

[0152] Embodiment 11

[0153] This embodiment provides a polyethylene environmentally friendly packaging material, which differs from Example 1 in that the barrier coating H1909 is replaced by an ordinary barrier PVA coating of equal thickness (manufacturer Shanghai Ruoyi New Materials, model H1900), and the other structures, parameters and preparation methods are the same as those in Example 1.

[0154] Example 12

[0155] This comparative example provides an environmentally friendly polyethylene packaging material, which differs from Example 1 in that the thickness of the extruded layer is adjusted to 15 μm, and other structures, parameters and preparation methods are the same as those of Example 1.

[0156] Comparative Example 1

[0157] This comparative example provides a polyethylene environmentally friendly packaging material, which is different from Example 1 in that the polyethylene environmentally friendly packaging material is not provided with a barrier coating, and other structures, parameters and preparation methods are the same as those of Example 1.

[0158] The performance tests were performed on the polyethylene environmentally friendly packaging materials of Examples 1-12 and Comparative Example 1, and the test methods / standards were as follows:

[0159] (1) Oxygen permeability: Oxygen permeability test was conducted according to the test method provided in GB / T 19789-2005. The test conditions were 23°C, 0% RH and 40°C, 90% RH.

[0160] (2) Water vapor transmission rate: The water vapor transmission rate test was conducted according to the test method provided in GB / T 26253-2010, and the test conditions were 38°C and 90% RH;

[0161] (3) Heat seal strength: Heat seal strength test shall be carried out according to the test method provided in QB / T 2358-1998;

[0162] (4) Peel strength of each layer: interlayer peel strength test shall be carried out in accordance with the provisions of GB / T 8808-1988;

[0163] (5) Sealing ability: According to the provisions of GB / T 15171-94, select 60kPa, 60s test;

[0164] (6) Drop resistance: drop from the front, back and bottom once each at a height of 1m and 1.5m.

[0165] The performance test results are shown in Table 4.

[0166] Table 4

[0167]

[0168] In Table 4, "sub-inner layer <1.5" means that the peel strength between the extruded layer and the middle layer is lower than 1.5N / 15mm.

[0169] The test results show that:

[0170] (1) It can be seen from Examples 1 to 3 that the polyethylene environmentally friendly packaging material of the present invention has excellent barrier properties and can meet the actual application needs of customers. Its oxygen permeability (0.1Mpa, 23°C, 0%RH) is ≤1cm 3 / (m 2 ·24h), water vapor transmission rate (38℃, 90%RH)≤1g / (m 2 ·24h), heat sealing strength ≥50N / 15mm, peel strength of each layer ≥3N / 15mm, sealing capacity 60kPa / 60s without leakage, and the bag will not break when dropped 3 times at a maximum of 1.5m; at the same time, its PE content is greater than 95%, meeting the standard requirements of a single recyclable material.

[0171] (2) By comparing Example 1 with Examples 4-7, it can be seen that the content of special high-density polyethylene in Example 6 is too high, and the bag breaks after falling 3 times at 1.5 m, that is, the anti-drop performance is poor; the content of special high-density polyethylene in Example 7 is too low, and its water vapor transmission rate (38°C, 90% RH) is 2 g / (m 2 ·24h), that is, the moisture barrier ability is significantly reduced. This shows that the present invention can make the polyethylene environmentally friendly packaging material have good comprehensive technical effects of moisture barrier and anti-drop performance by further optimizing the addition amount of special high-density polyethylene and metallocene polyethylene as the raw materials for preparing the core layer in the heat-sealing layer structure.

[0172] (3) By comparing Example 1 with Examples 8-10, it can be seen that the thickness of the core layer in the heat-sealing layer of Example 8 is too high, and the bag is broken after falling 3 times at 1.5 m, that is, the anti-drop performance is poor; the thickness of the core layer in the heat-sealing layer of Example 10 is too low, and its water vapor transmission rate (38°C, 90% RH) is 3.5 g / (m 2 ·24h), that is, the moisture barrier ability is significantly reduced. This shows that the present invention can achieve a better comprehensive technical effect of moisture barrier and anti-drop performance by optimizing the thickness ratio of each layer in the heat sealing layer structure.

[0173] (4) By comparing Example 1 with Comparative Example 1, it can be seen that Comparative Example 1 does not set a barrier coating, and it cannot achieve a good oxygen barrier effect; further, by comparing Example 1 with Example 11, it can be seen that the present invention can improve the oxygen barrier ability of the obtained polyethylene environmentally friendly packaging material under high humidity conditions by setting a modified barrier coating.

[0174] (5) By comparing Example 1 with Example 12, it can be seen that the selection of an extruded layer of a specific thickness can obtain higher peel strength and good drop resistance performance.

[0175] In summary, the all-polyethylene packaging material provided by the present invention has excellent moisture and oxygen barrier properties, heat sealing strength, peel strength, pressure-bearing sealing capacity and anti-drop performance through specific selection and optimization of the raw materials and thickness of the specific structural layer. The material is single, recyclable, green and economical, and can well meet the actual application needs of customers.

[0176] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A polyethylene environmentally friendly packaging material, characterized in that: The polyethylene environmentally friendly packaging material comprises a printing layer, a barrier coating layer, an intermediate layer and a heat-sealing layer which are arranged in sequence.

2. The environmentally friendly polyethylene packaging material according to claim 1, characterized in that: The heat sealing layer is a three-layer co-extruded PE layer; Preferably, the three-layer co-extruded PE layer comprises a composite layer, a core layer and an inner layer arranged in sequence; Preferably, the raw materials for preparing the composite layer include metallocene polyethylene and low-density polyethylene; Preferably, the metallocene polyethylene has a melt index of 0.5-2 g / 10 min at 190°C / 2.16 kg and a density of 0.91-0.94 g / cm 3 ; Preferably, the low-density polyethylene has a melt index of 0.5-4 g / 10 min at 190°C / 2.16 kg and a density of 0.92-0.94 g / cm 3 ; Preferably, the raw materials for preparing the core layer include special high-density polyethylene and metallocene polyethylene; Preferably, the special high-density polyethylene has a melt index of 0.5-2 g / 10 min at 190°C / 2.16 kg and a density of 0.96-0.97 g / cm 3 ; Preferably, the raw materials for preparing the inner layer include low-temperature metallocene polyethylene and metallocene polyethylene; Preferably, the low-temperature metallocene polyethylene has a melt index of 0.5-8 g / 10 min at 190°C / 2.16 kg and a density of 0.90-0.91 g / cm 3 .

3. The environmentally friendly polyethylene packaging material according to claim 2, characterized in that: The raw materials for preparing the composite layer also include fluorine-free processing aids; Preferably, based on the total mass of the raw materials for preparing the composite layer as 100%, the content of the metallocene polyethylene is 82-89%, the content of the low-density polyethylene is 10-15%, and the content of the fluorine-free processing aid is 1-3%; Preferably, based on the total mass of the raw materials for preparing the core layer as 100%, the content of the special high-density polyethylene is 50-80%, and the content of the metallocene polyethylene is 20-50%; Preferably, the raw materials for preparing the inner layer further include an opening agent and a fluorine-free processing aid; Preferably, based on the total mass of the raw materials for preparing the inner layer as 100%, the content of the low-temperature metallocene polyethylene is 50-83%, the content of the metallocene polyethylene is 15-45%, the content of the opening agent is 1-2%, and the content of the fluorine-free processing aid is 1-3%.

4. The environmentally friendly polyethylene packaging material according to claim 2 or 3, characterized in that: The thickness of the heat sealing layer is 70-120 μm; Preferably, the thickness ratio of the composite layer, the core layer and the inner layer is 1:(1-3):

1.

5. The environmentally friendly polyethylene packaging material according to any one of claims 1 to 4, characterized in that: The printing layer is a BOPE layer; Preferably, the BOPE layer is subjected to single-sided corona treatment; Preferably, the surface density of the printed layer is 0.94-0.96 g / cm 3 ; Preferably, the printing layer has a thickness of 20-40 μm; Preferably, the barrier coating is a modified PVOH coating; Preferably, the thickness of the barrier coating is 1-3 μm; Preferably, the middle layer is a BOPE layer; Preferably, the BOPE layer is subjected to double-sided corona treatment; Preferably, the surface density of the intermediate layer is 0.92-0.94 g / cm 3 ; Preferably, the thickness of the intermediate layer is 20-40 μm.

6. The environmentally friendly polyethylene packaging material according to any one of claims 1 to 5, characterized in that: A glue layer is also provided between the barrier coating and the intermediate layer; Preferably, the glue layer is a solvent-free glue layer; Preferably, the solvent-free glue layer comprises solvent-free polyurethane glue; Preferably, the amount of glue applied to the solvent-free glue layer is 1-2 g / m 2 .

7. The environmentally friendly polyethylene packaging material according to any one of claims 1 to 6, characterized in that: An extrusion layer is also provided between the intermediate layer and the heat sealing layer; Preferably, the extruded layer is a PE layer; Preferably, the thickness of the extruded layer is 20-25 μm.

8. A method for preparing the polyethylene environmentally friendly packaging material according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: (1) coating a barrier coating on one side of the printed layer to obtain a printed layer / barrier coating; (2) melt-extrude the raw materials for preparing the heat-sealing layer through a three-layer co-extrusion process, cool and shape, and perform corona treatment on the composite layer to obtain the heat-sealing layer; The steps (1) and (2) are performed in no particular order; (3) Compounding the intermediate layer and the heat-sealing layer to obtain a first composite layer; (4) Compounding the printed layer / barrier coating of step (1) and the first composite layer of step (2), and aging them to obtain the polyethylene environmentally friendly packaging material.

9. The method for preparing the polyethylene environmentally friendly packaging material according to claim 8, characterized in that: The three-layer co-extrusion process described in step (2) is carried out in a three-layer co-extrusion blown film equipment; Preferably, the temperature of the melt coextrusion in step (2) is 160-250°C; Preferably, the aging temperature in step (4) is 30-50°C; Preferably, the ripening time in step (4) is 48-72 hours.

10. Use of the environmentally friendly polyethylene packaging material according to any one of claims 1 to 7 in pet food packaging bags.

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