High-barrier film material as well as preparation method and application thereof

Abstract

The invention discloses a high-barrier film material and a preparation method and application thereof, the high-barrier film material can be used for manufacturing oxygen-barrier and water-barrier sealing packaging materials, and the high-barrier film material comprises a PE composite film and an oxygen-barrier coating arranged on the surface of the PE composite film; the PE composite film comprises an outer polyethylene layer, an ultra-high density polyethylene layer, a high-toughness polyethylene layer, an ultra-high density polyethylene layer and an inner polyethylene layer which are stacked in sequence. The high-barrier film material has the advantages of being convenient to recycle, low in production and use cost, good in toughness and good in water-blocking and oxygen-blocking effect, can be used in oxygen-blocking and water-blocking sealing packaging materials in the fields of packaging of food such as milk and beverages and packaging of liquid medicines, and is simple in preparation process, convenient to operate and suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of packaging materials, and in particular to a high-barrier film material which is easy to recycle, has good water and oxygen barrier effects, and has low production cost, as well as a preparation method and application thereof. Background Art

[0002] In the field of food packaging, such as in liquid packaging materials such as milk, aluminum foil is generally used as the key film layer material for water and oxygen barriers, and is produced together with other film materials such as PE film to prepare packaging materials. However, on the one hand, the mixed use of metal materials and polymer materials in such packaging materials brings great challenges to the classification, recycling and reuse of materials, and it is difficult to achieve effective recycling of different raw materials; on the other hand, aluminum foil has the common brittleness of metal materials, and is prone to creases during use. In severe cases, it may also cause perforation of the aluminum foil, resulting in a decrease in the water and oxygen barrier properties of the aluminum foil, which is prone to contamination and deterioration of the packaged objects; on the other hand, the price of aluminum foil is relatively high, which increases the production cost of packaging materials. Summary of the invention

[0003] The present invention provides a high barrier film material and a preparation method and application thereof, which are used to solve the technical problems mentioned in the background technology that the existing packaging materials are difficult to effectively recycle, the oxygen and water barrier properties are easily affected, and the cost is relatively high.

[0004] In order to solve the above technical problems, the technical solution proposed by the present invention is: A high barrier film material comprises a PE composite film and an oxygen barrier coating arranged on the surface of the PE composite film; the PE composite film comprises an outer polyethylene layer, an ultra-high density polyethylene layer, a high-toughness polyethylene layer, an ultra-high density polyethylene layer and an inner polyethylene layer stacked in sequence.

[0005] The design idea of ​​the above technical scheme is that the present invention realizes the water barrier function by providing a PE composite film with a high-density polyethylene layer, and realizes the oxygen barrier function by an oxygen barrier coating, thereby obtaining good oxygen and water barrier effects, and can replace aluminum foil as a new barrier material. Since the types and properties of the structural raw materials of each layer in the composite film are basically the same and the price is low and easy to obtain, they can be effectively recycled without separation during recycling, and the recycling and production costs are significantly reduced, thereby improving the use value of the product; at the same time, the present invention arranges a high-toughness polyethylene layer between the ultra-high-density polyethylene layers with greater brittleness, and uses the high-toughness polyethylene layer to protect the ultra-high-density polyethylene layer, thereby improving the overall toughness of the membrane material, and can effectively avoid the problem of decreased water and oxygen barrier properties caused by damage to the membrane material due to bending, pressure, etc. during use.

[0006] As a further preferred embodiment of the above technical solution, the relative density of the ultra-high density polyethylene layer is 0.950-0.970. The higher the density of the polyethylene layer, the better the water-blocking effect. The inventors have found through research and experiments that the ultra-high density polyethylene layer within the above density range can meet the market's requirements for the water-blocking effect of the membrane material.

[0007] As a further preferred embodiment of the above technical solution, the outer polyethylene layer is a medium-density polyethylene layer; the density of the medium-density polyethylene layer is in the range of 0.930 to 0.940. If the density of the outer polyethylene layer is too high, the strength is reduced and it is easy to fall off; if the density of the outer polyethylene layer is too low, it is easy to break when the use temperature is high; therefore, the present invention selects a medium-density polyethylene layer in the above density range as the outer polyethylene layer, so as to achieve a balance between strength and use temperature.

[0008] As a further preferred embodiment of the above technical solution, the high-toughness polyethylene layer is a metallocene polyethylene layer.

[0009] As a further preferred embodiment of the above technical solution, the inner polyethylene layer is a low-density polyethylene layer; the density range of the low-density polyethylene layer is 0.910~0.920. The low-density polyethylene layer is selected as the inner polyethylene layer because in the field of food packaging materials, a film is generally formed on one side of the water-blocking and oxygen-blocking layer to form an EAA layer, and the low-density polyethylene layer in the above density range has the characteristics of a low melting point, a fast filming speed, and a good bonding effect, which is convenient for the EAA filming process.

[0010] As a further preferred embodiment of the above technical solution, the oxygen barrier coating includes a PVA layer and an aluminum oxide layer coated on the surface of the outer polyethylene layer; or the oxygen barrier coating includes an EVOH layer coated on the surface of the outer polyethylene layer, and the EVOH layer is bonded to the surface of the outer polyethylene layer through an adhesive layer.

[0011] As a further preferred embodiment of the above technical solution, the total thickness of the PE composite film is 20-40 μm, and more preferably 25-30 μm; the thickness ratio of the outer polyethylene layer, the ultra-high density polyethylene layer, the high-toughness polyethylene layer, the ultra-high density polyethylene layer and the inner polyethylene layer is 20: (26-26.5): (7-8): (26-26.5): 20. The thickness ratio considerations of each structural layer include: high-density polyethylene gives the material high water resistance, but also increases the brittleness of the material. The role of high-toughness polyethylene is to reduce the brittleness of the material, but the toughness of the material cannot be too large, because too much toughness will affect die cutting. The inner and outer layers of low-density polyethylene need to have a lower melting point for easy lamination.

[0012] As a further preferred embodiment of the above technical solution, the outer polyethylene layer is formed by stacking 1 to 2 polyethylene layers; the ultra-high density polyethylene layer is formed by stacking 1 to 3 polyethylene layers. Multi-layer stacking can make the performance of the polyethylene layer and the membrane material as a whole more stable, and can improve the stability of water resistance and strength.

[0013] Based on the same technical concept, the present invention also provides a method for preparing the above-mentioned high barrier film material, comprising the following steps: The preparation method comprises the steps of feeding, heating and melting, co-extrusion, film blowing, cooling and shaping, traction, slitting and winding. The film blowing and cooling and shaping stage is to obtain all the film layers by one-time film blowing molding by a film blowing machine, and the thick film stretching and extending operation is continuously performed during the traction process. The number of flow channels of the die head of the film blowing machine is consistent with the number of layers of the high oxygen barrier film material to be prepared, and the flow channel opening size is widened to correspond to the layer thickness ratio of the high barrier film material.

[0014] Based on the same technical concept, the present invention also provides an application of the above-mentioned high barrier film material, which is used to make oxygen- and water-resistant sealed packaging materials, such as food packaging materials such as milk and beverages, liquid medicine packaging materials, etc.

[0015] As a further preferred embodiment of the above technical solution, the sealed packaging material comprises a polyethylene layer, a laminated EAA layer, the high barrier film material, a laminated EAA layer and a polyethylene layer stacked in sequence.

[0016] The present invention has the following beneficial effects: The high barrier film material of the present invention has the advantages of convenient recycling, low production and use cost, good toughness, and excellent water and oxygen barrier effects. It can be used in oxygen and water barrier sealing packaging materials in fields such as milk, beverage and other food packaging and liquid medicine packaging. The preparation process is simple, the operation is convenient, and it is suitable for large-scale industrial production.

[0017] The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of the PE composite film of the high barrier film material of Example 1; Figure 2 This is a schematic structural diagram of the sealing packaging material of Example 1; Figure 3 A schematic diagram of the structure of a PE composite film of a high barrier film material of Example 2; Figure 4 This is a schematic diagram of the structure of the PE composite film of the high barrier film material of Example 3. DETAILED DESCRIPTION

[0019] The embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0020] Embodiment 1: Table 1. High barrier material parameter design table of Example 1

[0021] like Figure 1 As shown in Table 1, the high barrier film material of this embodiment includes a PE composite film and an oxygen barrier coating arranged on the surface of the PE composite film, wherein the PE composite film includes an outer polyethylene layer (L2), an ultra-high density polyethylene layer (L3), a high-toughness polyethylene layer (L4), an ultra-high density polyethylene layer (L5) and an inner polyethylene layer (L6) stacked in sequence; the relative density of the ultra-high density polyethylene layer is 0.961; the outer polyethylene layer is a medium-density polyethylene layer, and the relative density of the medium-density polyethylene layer is 0.925; the high-toughness polyethylene layer is a metallocene polyethylene layer; the inner polyethylene layer is a low-density polyethylene layer, and the relative density of the low-density polyethylene layer is 0.920; the total thickness of the PE composite film is 28 μm, and the thickness ratio of the outer polyethylene layer, the ultra-high density polyethylene layer, the high-toughness polyethylene layer, the ultra-high density polyethylene layer and the inner polyethylene layer is 20:26.5:7:26.5:20; the oxygen barrier coating includes a PVA layer and an aluminum oxide layer coated on the surface of the outer polyethylene layer, and the thickness is 0.5 μm.

[0022] The preparation method of the high barrier film material of this embodiment includes multiple steps of feeding, heating and melting, co-extrusion, film blowing, cooling and shaping, pulling, and winding. The specific operations are as follows: S1: The raw materials of the outer polyethylene layer, the ultra-high density polyethylene layer, the high-toughness polyethylene layer, the ultra-high density polyethylene layer, and the inner polyethylene layer are transported from their respective storage tanks to the hoppers of the extruders; during the transportation process, the raw material particles pass through an automatic weighing system, and the raw material particles are added to the hoppers of the extruders according to the ratio in the formula in the automatic weighing system. The material ratio is completed during the transportation process, the metering is accurate, and the weighing process in the processing process is reduced.

[0023] S2: In this embodiment, there are five hoppers, which are used to store the raw material particles of each layer respectively. In other embodiments, the number of hoppers may vary from 7 to 11 depending on the different film layer structures. Some hoppers may also be added to store functional additives. The raw material particles are stored in different hoppers, which is convenient for transportation and adjustment of the ratio of each component. It is suitable for different material ratios and makes the entire processing device more flexible. After the hopper is loaded, the raw material particles are heated, melted, distributed, co-extruded, and shaped by air ring cooling in the extruder to obtain a one-time formed film body.

[0024] S3: When the film is cooled and shaped by the air ring, the blowing ratio of the film is generally 1 to 3, and the traction ratio of the film is 4 to 6, so that the film material reaches the preset thickness.

[0025] S4: After being cooled and shaped by the air ring, the film body is flattened by a herringbone clamp and then pulled to form two layers of film, which enter a thick film stretching and extending mechanism for thick film stretching and extending operation. The thick film stretching and extending mechanism is provided with a film heating device and a film cooling device, and the thick film is stretched and extended by repeated alternation of hot and cold.

[0026] S5: After the thick film stretching operation, the film body undergoes a secondary cooling and shaping operation during the transportation process (but this operation is not necessary). The secondary cooling and shaping operation can be applied to the film body through an air ring cooling device or through multiple sets of horizontally arranged rollers to make the film material smoother and more uniform in performance; and the temperature of the film body after secondary cooling and shaping is controlled at 30℃~50℃. The film material moves in the roller to make the material smoother and the performance more uniform, and the physical function of each component is brought to the extreme.

[0027] S6: The film body after secondary cooling and shaping is pulled by a traction roller, post-processed and cooled, and then transported to the winding roller for winding. Specifically, a heating roller group and a cooling roller group can be set in the roller after the traction roller as needed. The heating roller group and the cooling roller group are alternately set to repeatedly heat and cool the film material, so that the roller can continue to heat or cool the film material after secondary cooling and shaping, so that the hardness of the material is improved and the ductility is better; the post-processing treatment is corona and trimming. After the film is post-processed, the two layers of film are cooled, shaped and rolled up respectively.

[0028] The high barrier film material of this embodiment can be used to make oxygen- and water-resistant sealed packaging materials, such as Figure 2 As shown, the sealed packaging material includes a polyethylene layer (A), a paper surface printing layer (B), a laminated EAA layer (C), a high barrier film material (L) of this embodiment, a laminated EAA layer (C) and a polyethylene layer (A) stacked in sequence.

[0029] Embodiment 2: Table 2. High barrier material parameter design table of Example 2

[0030] like Figure 3As shown in Table 2, the high barrier film material of this embodiment includes a PE composite film and an oxygen barrier coating arranged on the surface of the PE composite film, wherein the PE composite film includes an outer polyethylene layer (L2), two ultra-high density polyethylene layers (L3 and L4), a high toughness polyethylene layer (L5), two ultra-high density polyethylene layers (L6 and L7) and an inner polyethylene layer (L8) stacked in sequence; the relative density of the ultra-high density polyethylene layer is 0.961; the outer polyethylene layer is a medium density polyethylene layer, and the relative density of the medium density polyethylene layer is 0.925; the high toughness polyethylene layer is a metallocene polyethylene layer; the inner polyethylene layer is a low density polyethylene layer, and the relative density of the low density polyethylene layer is 0.920; the total thickness of the PE composite film is 28 μm, and the thickness ratio of the outer polyethylene layer, the ultra-high density polyethylene layer, the high toughness polyethylene layer, the ultra-high density polyethylene layer and the inner polyethylene layer is 20:26.5:7:26.5:20; the oxygen barrier coating includes a PVA layer and an aluminum oxide layer coated on the surface of the outer polyethylene layer, and the total thickness is 2 μm.

[0031] The preparation method of the high barrier film material of this embodiment includes multiple steps of feeding, heating and melting, co-extrusion, film blowing, cooling and shaping, pulling, and winding. The specific operation is similar to that of Example 1.

[0032] The high barrier film material of this embodiment can be used to make oxygen- and water-resistant sealed packaging materials. The sealed packaging materials include a polyethylene layer, a paper surface printing layer, a coated EAA layer, the high barrier film material of this embodiment, a coated EAA layer and a polyethylene layer stacked in sequence.

[0033] Embodiment 3: Table 3. High barrier material parameter design table of Example 3

[0034] like Figure 4As shown in Table 3, the high barrier film material of this embodiment includes a PE composite film and an oxygen barrier coating arranged on the surface of the PE composite film, wherein the PE composite film includes two outer polyethylene layers (L2 and L3), three ultra-high density polyethylene layers (L4, L5, L6), a high-toughness polyethylene layer (L7), three ultra-high density polyethylene layers (L8, L9, L10) and two inner polyethylene layers (L11 and L12) stacked in sequence; the relative density of the ultra-high density polyethylene layer is 0.961; the outer polyethylene layer is a medium-density polyethylene layer The relative density of the medium-density polyethylene layer is 0.925; the high-toughness polyethylene layer is a metallocene polyethylene layer; the inner polyethylene layer is a low-density polyethylene layer, and the relative density of the low-density polyethylene layer is 0.920; the total thickness of the PE composite film is 28μm, and the thickness ratio of the outer polyethylene layer, the ultra-high-density polyethylene layer, the high-toughness polyethylene layer, the ultra-high-density polyethylene layer and the inner polyethylene layer is 20:26:8:26:20; the oxygen barrier coating includes a PVA layer and an aluminum oxide layer coated on the surface of the outer polyethylene layer, with a total thickness of 2μm.

[0035] The performance of the high barrier film material of each embodiment was tested, and the results are shown in Table 4.

[0036] Table 4. Test results of high barrier film material performance of each embodiment:

[0037] The preparation method of the high barrier film material of this embodiment includes multiple steps of feeding, heating and melting, co-extrusion, film blowing, cooling and shaping, pulling, and winding. The specific operation is similar to that of Example 1.

[0038] The high barrier film material of this embodiment can be used to make oxygen- and water-resistant sealed packaging materials. The sealed packaging materials include a polyethylene layer, a paper surface printing layer, a coated EAA layer, the high barrier film material of this embodiment, a coated EAA layer and a polyethylene layer stacked in sequence.

[0039] At present, similar high-barrier sealed packaging materials (such as milk packaging materials) are generally only recycled for the pulp in the packaging materials, but there are problems such as low pulp yield, high proportion of impurities (aluminum-plastic), and poor pulp quality. If the aluminum-plastic film needs to be separated, it is necessary to invest tens of millions to upgrade the equipment, which is very costly. The oxygen- and water-resistant sealed packaging material of this embodiment has good recycling convenience and good recycling prospects.

[0040] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. For those skilled in the art, improvements and changes obtained without departing from the technical concept of the present invention should also be regarded as the protection scope of the present invention.

[0041] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A high barrier film material, characterized in that: It comprises a PE composite film and an oxygen barrier coating arranged on the surface of the PE composite film; the PE composite film comprises an outer polyethylene layer, an ultra-high density polyethylene layer, a high-toughness polyethylene layer, an ultra-high density polyethylene layer and an inner polyethylene layer which are stacked in sequence.

2. The high barrier film material according to claim 1, characterized in that: The density of the ultra-high density polyethylene layer is 0.950-0.970 g / cm 3 .

3. The high barrier film material according to claim 1, characterized in that: The outer polyethylene layer is a medium-density polyethylene layer; the relative density of the medium-density polyethylene layer is 0.930-0.940 g / cm 3 .

4. The high barrier film material according to claim 1, characterized in that: The high-toughness polyethylene layer is a metallocene polyethylene layer.

5. The high barrier film material according to claim 1, characterized in that: The inner polyethylene layer is a low-density polyethylene layer; the density of the low-density polyethylene layer ranges from 0.910 to 0.920 g / cm 3 .

6. The high barrier film material according to any one of claims 1 to 5, characterized in that: The oxygen barrier coating comprises a PVA layer and an aluminum oxide layer coated on the surface of the outer polyethylene layer; or the oxygen barrier coating comprises an EVOH layer coated on the surface of the outer polyethylene layer, and the EVOH layer is bonded to the surface of the outer polyethylene layer through an adhesive layer.

7. The high barrier film material according to any one of claims 1 to 5, characterized in that: The total thickness of the PE composite film is 20-40 μm, and the thickness ratio of the outer polyethylene layer, the ultra-high density polyethylene layer, the high-toughness polyethylene layer, the ultra-high density polyethylene layer and the inner polyethylene layer is 20:(26-26.5):(7-8):(26-26.5):

20.

8. The high barrier film material according to any one of claims 1 to 5, characterized in that: The outer polyethylene layer is formed by stacking 1 to 2 polyethylene layers; and the ultra-high density polyethylene layer is formed by stacking 1 to 3 polyethylene layers.

9. A method for preparing a high barrier film material according to any one of claims 1 to 8, characterized in that: The preparation method comprises the steps of feeding, heating and melting, co-extrusion, film blowing, cooling and shaping, traction, slitting and winding. The film blowing and cooling and shaping stage is to obtain all the film layers by one-time film blowing molding by a film blowing machine, and the thick film stretching and extending operation is continuously performed during the traction process. The number of flow channels of the die head of the film blowing machine is consistent with the number of layers of the high oxygen barrier film material to be prepared, and the flow channel opening size is widened to correspond to the layer thickness ratio of the high barrier film material.

10. Use of the high barrier film material according to any one of claims 1 to 8 or the high barrier film material prepared by the preparation method according to claim 8, characterized in that: The high barrier film material is used to make oxygen- and water-resistant sealing packaging materials.

11. The use of the high barrier film material according to claim 10, characterized in that: The sealing packaging material comprises a polyethylene layer, a laminated EAA layer, the high barrier film material, a laminated EAA layer and a polyethylene layer which are stacked in sequence.

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