Degradable packaging film

Abstract

The utility model discloses a degradable packaging film, which comprises a blocking layer, a heat sealing layer, a flexible surface layer and a heat sealing layer, wherein the blocking layer is clamped between the flexible surface layer and the heat sealing layer; the reinforcing layer is clamped between the tough surface layer and the barrier layer and / or between the barrier layer and the heat sealing layer; the barrier layer comprises at least one unit nylon layer, at least one unit nylon layer is a degradable nylon barrier layer, and the tough surface layer and / or the reinforcing layer are / is provided with degradable layers; the reinforcing layer comprises at least one linear low-density polyethylene layer. The barrier layer contains the degradable nylon barrier layer, and the tough surface layer and / or the reinforcing layer are / is provided with the degradable layer, so that the degradation speed and the mechanical property of different materials are flexibly adjusted, and the problem that the nylon / polyethylene barrier packaging film is not easy to degrade is solved; the strength, the toughness, the rigidity, the tear resistance and the environmental stress cracking resistance of the packaging film are improved through the reinforcing layer containing the linear low-density polyethylene layer.

Description

Technical Field

[0001] This utility model relates to the field of packaging film technology, and in particular to a biodegradable packaging film. Background Art

[0002] With the development of the times and the continuous improvement of people's living standards, plastic packaging bags are widely used in people's lives due to their advantages such as low cost, lightweight, and variety. For packaging bags used directly in outdoor environments, they need to possess good barrier properties, impact resistance, tensile strength, and other mechanical properties, as well as good cold resistance, moisture resistance, and high-temperature resistance. Conventional packaging bags mainly use polyethylene co-extruded film, which has poor barrier properties. Therefore, nylon packaging film or a combination of nylon and polyethylene co-extruded film is often used to improve the barrier properties of the packaging bags. However, packaging bags made of nylon cannot be degraded by nature, and their disposal easily causes white pollution, which is detrimental to sustainable environmental development.

[0003] Therefore, it is necessary to improve the packaging films in the existing technology. Utility Model Content

[0004] The purpose of this invention is to overcome the defects in the existing technology and provide a biodegradable packaging film. This film has a barrier layer containing a biodegradable nylon barrier layer, and a tough surface layer and / or a reinforcing layer with a biodegradable layer. This allows for flexible adjustment of the degradation rate and mechanical properties of different materials, solving the problem of the difficulty in degrading nylon / polyethylene barrier packaging films. Furthermore, the reinforcing layer containing a linear low-density polyethylene layer improves the strength, toughness, rigidity, tear resistance, and environmental stress cracking resistance of the packaging film.

[0005] To achieve the above-mentioned technical effects, the technical solution of this utility model is: a biodegradable packaging film, comprising:

[0006] A barrier layer is sandwiched between a tough outer layer and a heat-sealing layer;

[0007] A reinforcing layer is sandwiched between the tough surface layer and the barrier layer, and / or between the barrier layer and the heat-sealing layer;

[0008] The barrier layer includes at least one unit nylon layer, and at least one unit nylon layer is a biodegradable nylon barrier layer. The tough surface layer and / or reinforcing layer are provided with a biodegradable layer.

[0009] The reinforcing layer comprises at least one layer of linear low-density polyethylene.

[0010] The preferred technical solution is that the reinforcing layer is a laminated structure of LDPE / LLDPE, LDPE / LLDPE / LLDPE, or LLDPE / LDPE / LLDPE.

[0011] A preferred technical solution is that the tough outer layer is one or a combination of nylon, mLLDPE and LLDPE.

[0012] A preferred technical solution is that at least one layer in the laminated structure of the reinforcing layer is a biodegradable layer.

[0013] A preferred technical solution is that the thickness of the LDPE layer accounts for 40% to 45% of the total thickness of the reinforcing layer, the total thickness of the reinforcing layer accounts for 25% to 29% of the total thickness of the packaging film, and the total thickness of the packaging film is 60 to 120 μm.

[0014] A preferred technical solution is that the tough outer layer and the reinforcing layer, the reinforcing layer and the barrier layer, and the barrier layer and the heat-sealing layer are all connected by an adhesive layer.

[0015] A preferred technical solution is that the adhesive layer contains linear low-density polyethylene.

[0016] The advantages and beneficial effects of this utility model are as follows:

[0017] The biodegradable packaging film has a reasonable structure. It contains a biodegradable nylon barrier layer in the barrier layer, and a biodegradable layer in the tough surface layer and / or reinforcing layer. It can flexibly adjust the degradation rate and mechanical properties of different materials, and solve the problem that nylon / polyethylene barrier packaging films are not easy to degrade.

[0018] The strength, toughness, rigidity, tear resistance, and environmental stress cracking resistance of the packaging film are improved by using a reinforcing layer containing a linear low-density polyethylene layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the biodegradable packaging film of this utility model;

[0020] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of the biodegradable packaging film of this utility model;

[0021] Figure 3 This is a schematic diagram of the structure of Embodiment 3 of the biodegradable packaging film of this utility model.

[0022] In the diagram: 1. Tough surface layer; 2. Barrier layer; 3. Heat-sealing layer; 4. Reinforcing layer; 10. Adhesive layer; 20. Unit nylon layer. DETAILED DESCRIPTION

[0023] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solution of this utility model and should not be construed as limiting the scope of protection of this utility model.

[0024] The terms “surface,” “outer surface,” and “inner surface” refer to the normal use state of the biodegradable packaging film and are used only for the convenience of describing this utility model and simplifying the description. They are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0025] like Figures 1-3 As shown, the biodegradable packaging film disclosed in this utility model includes a barrier layer 2, a reinforcing layer 4, a tough surface layer 1, and a heat-sealing layer 3. The barrier layer 2 is sandwiched between the tough surface layer 1 and the heat-sealing layer 3, while the reinforcing layer 4 can be sandwiched between the tough surface layer 1 and the barrier layer 2, between the barrier layer 2 and the heat-sealing layer 3, or both between the tough surface layer 1 and the barrier layer 2 and between the barrier layer 2 and the heat-sealing layer 3.

[0026] In some embodiments, the barrier layer 2 is a single-layer unit nylon layer 20, which is a biodegradable nylon barrier layer.

[0027] In some embodiments, the barrier layer 2 includes a bilayer unit nylon layer 20, one of which is a biodegradable nylon barrier layer.

[0028] Achieving biodegradability in the barrier layer requires the addition of biodegradable materials, such as polylactic acid, thermoplastic starch, chitosan, and degradation promoters. However, adding biodegradable components can reduce the film's strength and toughness; transparency may decrease due to the addition of opaque or translucent particles; degradation additives can affect the composite film's thermal stability, melting point, and processing window; and the addition of natural materials can increase hygroscopicity, affecting the moisture resistance and gas barrier properties of packaged foods. Therefore, one of the double-layer nylon units is a biodegradable nylon barrier layer, which achieves both biodegradability and excellent mechanical properties in the packaging film. Simultaneously, the mechanical properties of the packaging film are improved through reinforcing layers.

[0029] Since the barrier layer is a biodegradable nylon barrier layer, or the barrier layer contains a biodegradable nylon barrier layer, in order to improve the durability, moisture resistance and mechanical properties of the packaging film, a reinforcing layer is further sandwiched between the tough surface layer and the barrier layer, or a reinforcing layer is sandwiched between the tough surface layer and the barrier layer and between the barrier layer and the heat-sealing layer.

[0030] To optimize the degradation effect and rate of the packaging film, in some embodiments, the tough surface layer 1 is made of nylon, thus making it a biodegradable layer. In some embodiments, when the tough surface layer 1 is made of nylon and is a biodegradable layer, and the reinforcing layer 4 is a three-layer laminated structure, at least one layer in the laminated structure of the reinforcing layer is a biodegradable layer. In some embodiments, the tough surface layer 1 is one or a combination of mLLDPE and LLDPE, and at least one layer in the laminated structure of the reinforcing layer 4 is a biodegradable layer, thereby improving the surface impact resistance, toughness, and other mechanical properties of the packaging film.

[0031] The reinforcing layer 4 is a laminated structure of LDPE / LLDPE, LDPE / LLDPE / LLDPE, and LLDPE / LDPE / LLDPE. Reinforcing layer 4 effectively improves the adhesion between the tough outer layer 1 and the barrier layer 2, preventing delamination; it also improves the barrier properties of the co-extruded film against water, water vapor, and air, while shortening the degradation time of the co-extruded film from the surface to the inner layers. LDPE has a low density and is one of the lightest varieties of polyethylene resin; due to its long molecular chains and numerous branches, LDPE possesses excellent flexibility and extensibility. The tough outer layer of nylon and the biodegradable nylon barrier layer have high hardness, thus the LDPE layer optimizes the hardness and toughness of the protective film; it improves the processability, flexibility, and sealing of the packaging film; and by adjusting the layer thickness, it improves transparency, preventing the negative impact of biodegradable materials on the optical properties of the packaging film. LLDPE has a more linear molecular structure without long branches, resulting in a narrower molecular weight distribution. In biodegradable packaging films, this may lead to a more consistent response to specific degradation conditions and easier decomposition. Compared to LDPE, LLDPE has higher strength, toughness, rigidity, and tear resistance; it also has better resistance to environmental stress cracking, making it suitable for packaging materials requiring long-term outdoor use. Furthermore, the LDPE layer thickness accounts for 40%–45% of the total reinforcing layer thickness, the reinforcing layer thickness accounts for 25%–29% of the total packaging film thickness, and the total packaging film thickness is 60–120 μm.

[0032] The tough outer layer 1 is connected to the reinforcing layer 4, the reinforcing layer 4 to the barrier layer 2, and the barrier layer 2 to the heat-sealing layer 3 by an adhesive layer 10. The adhesive layer 10 contains linear low-density polyethylene (LLDPE). Furthermore, the adhesive layer 10 is a mixture of LLDPE and an adhesive, with a mass ratio of LLDPE to adhesive of 3:1. The adhesive is modified from LLDPE, exhibiting good adhesion when combined with LLDPE, which also helps reduce the cost of the packaging film and shortens the degradation time of the co-extruded film from the outer layer to the inner layer.

[0033] Example 1

[0034] like Figure 1 As shown, the biodegradable packaging film comprises, from the outside in, a tough outer layer 1, a reinforcing layer 4, a barrier layer 2, and a heat-sealing layer 3, stacked sequentially. The tough outer layer 1 is made of nylon and is a biodegradable layer. The reinforcing layer 4 has a laminated structure of LDPE / LLDPE. The barrier layer 2 is a double-layer nylon 20, with the biodegradable nylon barrier layer adjacent to the tough outer layer 1. The tough outer layer 1 and the reinforcing layer 4, the reinforcing layer 4 and the barrier layer 2, and the barrier layer 2 and the heat-sealing layer 3 are all connected by an adhesive layer 10. That is, the tough outer layer 1 and the barrier layer 2 contain biodegradable materials.

[0035] The tough outer layer 1 has a thickness of 9 μm, the reinforcing layer 4 has a thickness of 24 μm, the barrier layer 2 has a thickness of 11 μm, the heat-sealing layer 3 has a thickness of 25 μm, and the single-layer adhesive layer 10 has a thickness of 7 μm.

[0036] Example 2

[0037] like Figure 2 As shown, Example 2 is based on Example 1, except that the tough outer layer 1 is made of mLLDPE, the reinforcing layer 4 is a laminated structure of LDPE / LLDPE / LLDPE, and the barrier layer 2 is a single-layer nylon layer 20, which is a biodegradable nylon barrier layer. Specifically, the LDPE layer in the reinforcing layer 4 is a biodegradable layer. That is, both the reinforcing layer 4 and the barrier layer 2 contain biodegradable materials.

[0038] The tough outer layer 1 has a thickness of 9 μm, the reinforcing layer 4 has a thickness of 25 μm, the barrier layer 2 has a thickness of 10 μm, the heat-sealing layer 3 has a thickness of 25 μm, and the single-layer adhesive layer 10 has a thickness of 7 μm.

[0039] Example 3

[0040] like Figure 3 As shown, Example 3 is based on Example 1, except that the material of the tough surface layer 1 remains the same, the reinforcing layer 4 is a laminated structure of LLDPE / LDPE / LLDPE, the barrier layer 2 is a single-layer nylon layer 20, and the barrier layer 2 is a biodegradable nylon barrier layer. Specifically, the LDPE layer in the reinforcing layer 4 is a biodegradable layer. That is, the tough surface layer 1, the reinforcing layer 4, and the barrier layer 2 all contain biodegradable materials.

[0041] The tough outer layer 1 has a thickness of 9 μm, the reinforcing layer 4 has a thickness of 25 μm, the barrier layer 2 has a thickness of 10 μm, the heat-sealing layer 3 has a thickness of 25 μm, and the single-layer adhesive layer 10 has a thickness of 7 μm.

[0042] Tensile strength of packaging films in Examples 1-3: 20-25 MPa in the longitudinal direction and 20-25 MPa in the transverse direction; Elongation at break: 300%-350% in the longitudinal direction and 300%-350% in the transverse direction; Oxygen transmittance: less than 50 cm⁻¹ 3 / m 2 ·day.

[0043] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A degradable packaging film, characterized in that: include: A barrier layer, sandwiched between the tough surface layer and the heat seal layer; A reinforcing layer, sandwiched between the tough surface layer and the barrier layer, and / or between the barrier layer and the heat-sealing layer; The barrier layer comprises at least one unit nylon layer, at least one unit nylon layer is a degradable nylon barrier layer, and the tough surface layer and / or the reinforcement layer are provided with a degradable layer; The reinforcement layer comprises at least one linear low-density polyethylene layer.

2. The degradable packaging film according to claim 1, characterized in that: The reinforcing layer is LDPE / LLDPE, LDPE / LLDPE / LLDPE, LLDPE / LDPE / The layered structure of LLDPE.

3. The degradable packaging film according to claim 1, characterized in that: The tough surface layer is one or a combination of nylon, mLLDPE and LLDPE.

4. The degradable packaging film according to claim 2 or 3, characterized in that: At least one layer in the laminated structure of the reinforcement layer is a degradable layer.

5. The degradable packaging film according to claim 2, characterized in that: The layer thickness of the LDPE accounts for 40% to 45% of the total layer thickness of the reinforcement layer, the total layer thickness of the reinforcement layer accounts for 25% to 29% of the total film thickness of the packaging film, and the total film thickness of the packaging film is 60 to 120 μm.

6. The degradable packaging film according to claim 1, characterized in that: The tough surface layer and the reinforcement layer, the reinforcement layer and the barrier layer, and the barrier layer and the heat-sealing layer are all connected via adhesive layers.

7. The degradable packaging film according to claim 6, characterized in that: The glue layer contains linear low-density polyethylene.

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