A single material high barrier recyclable composite film

Abstract

The application relates to the technical field of food packaging, and proposes a single-material high-barrier recyclable composite film which comprises a first PE film layer, a second PE film layer and a third PE film layer, the first PE film layer comprises low-density polyethylene, inorganic antibacterial agent, EVOH, glutaraldehyde and neopentyl glycol diacrylate; the second PE film layer comprises metallocene polyethylene and organic antibacterial agent; and the third PE film layer comprises high-density polyethylene, inorganic antibacterial agent, EVOH, glutaraldehyde, neopentyl glycol diacrylate and lubricant. Through the technical scheme, the problems of poor barrier performance and poor mechanical performance of the packaging film in the prior art are solved.

Description

Technical Field

[0001] This invention relates to the field of food packaging technology, specifically to a high-barrier recyclable composite film made of a single material. Background Technology

[0002] With the continuous advancement of social science and technology, a wide variety of products are adopting increasingly diverse packaging designs to meet market demands, which in turn places higher requirements on the barrier properties of the packaging films.

[0003] The barrier properties of packaging materials are crucial for protecting the contents. Firstly, there's the barrier property of water vapor. For foods rich in moisture, if the packaging material's water vapor permeability is too high, it means the moisture loss is too rapid, easily leading to dehydration and loss of texture. Secondly, there's the barrier property of oxygen. Especially for foods with high fat content, the fat is easily oxidized under the influence of oxygen, severely degrading product quality and even jeopardizing food safety. Furthermore, the mechanical properties of the packaging film are even more important for protecting the contents.

[0004] High-barrier plastic flexible packaging has gained widespread application. Common materials include silica vapor-deposited films and ethylene-polyvinyl alcohol copolymer films. Each of these materials has its own advantages and disadvantages. Silica vapor-deposited films are too expensive and suffer from mechanical fatigue; their barrier properties decrease during lamination, packaging, and storage / transport due to damage to the inorganic barrier layer. Ethylene-polyvinyl alcohol copolymer films experience a significant decrease in barrier properties with increasing humidity, and their barrier properties against water vapor are poor. Therefore, providing a packaging film with both good barrier properties and good mechanical properties is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This invention proposes a high-barrier recyclable composite film made of a single material, which solves the problems of poor barrier performance and poor mechanical properties of packaging films in related technologies.

[0006] The technical solution of the present invention is as follows:

[0007] A high-barrier recyclable composite membrane made of a single material includes a first PE membrane layer, a second PE membrane layer and a third PE membrane layer, wherein the first PE membrane layer includes low-density polyethylene, inorganic antibacterial agent, EVOH, glutaraldehyde and neopentyl glycol diacrylate.

[0008] The second PE film layer comprises metallocene polyethylene and an organic antibacterial agent;

[0009] The third PE film layer comprises high-density polyethylene, inorganic antibacterial agent, EVOH, glutaraldehyde, neopentyl glycol diacrylate, and lubricant.

[0010] EVOH is an ethylene-vinyl alcohol copolymer.

[0011] As a further technical solution, the first PE film layer comprises the following components in parts by weight: 90-110 parts of low-density polyethylene, 5-10 parts of inorganic antibacterial agent, 10-15 parts of EVOH, 5-10 parts of glutaraldehyde, and 5-10 parts of neopentyl glycol diacrylate.

[0012] As a further technical solution, the second PE film layer comprises the following components in parts by weight: 80-100 parts of metallocene polyethylene and 3-5 parts of organic antibacterial agent.

[0013] As a further technical solution, the third PE film layer comprises the following components in parts by weight: 90-110 parts of high-density polyethylene, 5-10 parts of inorganic antibacterial agent, 10-15 parts of EVOH, 5-10 parts of glutaraldehyde, 5-10 parts of neopentyl glycol diacrylate, and 3-5 parts of lubricant.

[0014] As a further technical solution, the mass ratio of glutaraldehyde to neopentyl glycol diacrylate in the first PE film layer and the third PE film layer is 1:1.

[0015] As a further technical solution, the inorganic antibacterial agents in the first PE film layer and the third PE film layer each independently include one or more of silver oxide, zinc oxide, titanium dioxide, and zinc silicate.

[0016] As a further technical solution, the organic antibacterial agent is Sandan oil.

[0017] As a further technical solution, the lubricant includes one or more of zinc stearate, calcium stearate, magnesium stearate, and paraffin wax.

[0018] As a further technical solution, the thickness ratio of the first PE film layer, the second PE film layer, and the third PE film layer is 2:1:1.

[0019] This invention also proposes a method for preparing a high-barrier recyclable composite membrane made of a single material, comprising the following steps:

[0020] S1. Mix low-density polyethylene, inorganic antibacterial agent, EVOH, glutaraldehyde and neopentyl glycol diacrylate, melt extrude and granulate to obtain the first PE film layer material;

[0021] S2. Mix metallocene polyethylene and organic antibacterial agent, melt extrude and granulate to obtain the second PE film layer material;

[0022] S3. Mix high-density polyethylene, inorganic antibacterial agent, EVOH, glutaraldehyde, neopentyl glycol diacrylate and lubricant, melt extrude and granulate to obtain the third PE film layer material;

[0023] S4. The first PE film layer material, the second PE film layer material, and the third PE film layer material are co-extruded to obtain a high-barrier recyclable composite film.

[0024] The working principle and beneficial effects of this invention are as follows:

[0025] 1. This invention provides a high-barrier recyclable composite membrane made of a single material. EVOH provides excellent barrier properties to the composite membrane. However, since the EVOH structure contains a large number of hydrophilic hydroxyl groups, it is easy to absorb moisture, which reduces the barrier properties. Therefore, this invention uses glutaraldehyde and neopentyl glycol diacrylate to synergistically reduce the hygroscopicity of the composite membrane, thereby improving the barrier properties of the composite membrane.

[0026] 2. In this invention, the EVOH structure contains a large number of hydroxyl groups, and the neopentyl glycol diacrylate structure contains ester groups. Although hydrogen bonds can be formed between EVOH molecules, it is an organic polymer with long molecular chains that are prone to entanglement. Therefore, this invention adds neopentyl glycol diacrylate organic small molecules and utilizes the easy formation of hydrogen bonds between EVOH and neopentyl glycol diacrylate to further strengthen the intermolecular forces, thereby further improving the barrier properties and mechanical properties of the composite film.

[0027] 3. Traditional composite films are made by laminating different materials to achieve a combination of film properties. Some have good moisture and oxygen barrier properties, while others have good heat-sealing properties. While this lamination achieves functional synergy, it also presents recycling challenges. One reason for the difficulty in recycling packaging after use is the difficulty in decomposing the different materials. This invention uses a three-layer polyethylene (PE) composite material. The single material is more conducive to recycling, making it an environmentally friendly packaging material. It also possesses good barrier and mechanical properties. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] In the following examples and comparative examples, the thickness ratio of the first PE film layer, the second PE film layer, and the third PE film layer is 2:1:1.

[0030] Example 1

[0031] S1. Mix 100 parts of low-density polyethylene, 5 parts of silver oxide, 10 parts of EVOH, 8 parts of glutaraldehyde and 8 parts of neopentyl glycol diacrylate, melt extrude and granulate to obtain the first PE film layer material.

[0032] S2. Mix 80 parts of metallocene polyethylene and 5 parts of tannin oil, melt extrude and granulate to obtain the second PE film layer material;

[0033] S3. Mix 100 parts of high-density polyethylene, 8 parts of titanium dioxide, 15 parts of EVOH, 8 parts of glutaraldehyde, 8 parts of neopentyl glycol diacrylate and 5 parts of calcium stearate, melt extrude and granulate to obtain the third PE film layer material.

[0034] S4. The first PE film layer material, the second PE film layer material, and the third PE film layer material are co-extruded to obtain a high-barrier recyclable composite film.

[0035] Example 2

[0036] S1. Mix 90 parts of low-density polyethylene, 8 parts of zinc oxide, 12 parts of EVOH, 5 parts of glutaraldehyde and 5 parts of neopentyl glycol diacrylate, melt extrude and granulate to obtain the first PE film layer material.

[0037] S2. Mix 90 parts of metallocene polyethylene and 3 parts of tannin oil, melt extrude and granulate to obtain the second PE film layer material;

[0038] S3. Mix 110 parts of high-density polyethylene, 10 parts of zinc silicate, 12 parts of EVOH, 10 parts of glutaraldehyde, 10 parts of neopentyl glycol diacrylate and 4 parts of paraffin wax, melt extrude and granulate to obtain the third PE film layer material.

[0039] S4. The first PE film layer material, the second PE film layer material, and the third PE film layer material are co-extruded to obtain a high-barrier recyclable composite film.

[0040] Example 3

[0041] S1. Mix 110 parts of low-density polyethylene, 10 parts of titanium dioxide, 15 parts of EVOH, 10 parts of glutaraldehyde and 10 parts of neopentyl glycol diacrylate, melt extrude and granulate to obtain the first PE film layer material.

[0042] S2. Mix 100 parts of metallocene polyethylene and 4 parts of tannin oil, melt extrude and granulate to obtain the second PE film layer material;

[0043] S3. Mix 90 parts of high-density polyethylene, 5 parts of titanium dioxide, 10 parts of EVOH, 5 parts of glutaraldehyde, 5 parts of neopentyl glycol diacrylate and 3 parts of zinc stearate, melt extrude and granulate to obtain the third PE film layer material.

[0044] S4. The first PE film layer material, the second PE film layer material, and the third PE film layer material are co-extruded to obtain a high-barrier recyclable composite film.

[0045] Example 4

[0046] S1. Mix 100 parts of low-density polyethylene, 5 parts of silver oxide, 10 parts of EVOH, 8 parts of glutaraldehyde and 5 parts of neopentyl glycol diacrylate, melt extrude and granulate to obtain the first PE film layer material.

[0047] S2. Mix 80 parts of metallocene polyethylene and 5 parts of tannin oil, melt extrude and granulate to obtain the second PE film layer material;

[0048] S3. Mix 100 parts of high-density polyethylene, 8 parts of titanium dioxide, 15 parts of EVOH, 8 parts of glutaraldehyde, 8 parts of neopentyl glycol diacrylate and 5 parts of calcium stearate, melt extrude and granulate to obtain the third PE film layer material.

[0049] S4. The first PE film layer material, the second PE film layer material, and the third PE film layer material are co-extruded to obtain a high-barrier recyclable composite film.

[0050] Example 5

[0051] S1. Mix 100 parts of low-density polyethylene, 5 parts of silver oxide, 10 parts of EVOH, 8 parts of glutaraldehyde and 10 parts of neopentyl glycol diacrylate, melt extrude and granulate to obtain the first PE film layer material.

[0052] S2. Mix 80 parts of metallocene polyethylene and 5 parts of tannin oil, melt extrude and granulate to obtain the second PE film layer material;

[0053] S3. Mix 100 parts of high-density polyethylene, 8 parts of titanium dioxide, 15 parts of EVOH, 8 parts of glutaraldehyde, 8 parts of neopentyl glycol diacrylate and 5 parts of calcium stearate, melt extrude and granulate to obtain the third PE film layer material.

[0054] S4. The first PE film layer material, the second PE film layer material, and the third PE film layer material are co-extruded to obtain a high-barrier recyclable composite film.

[0055] Comparative Example 1

[0056] The only difference from Example 1 is that glutaraldehyde is not added in S1.

[0057] Comparative Example 2

[0058] The only difference from Example 1 is that neopentyl glycol diacrylate is not added in S1.

[0059] Comparative Example 3

[0060] The only difference from Example 1 is that glutaraldehyde and neopentyl glycol diacrylate are not added in S1.

[0061] The composite films of the same thickness obtained from Examples 1-5 and Comparative Examples 1-3 were tested for water resistance according to GB / T 1540-2002; oxygen barrier properties according to GB / T 1038-2000; and tensile strength and elongation at break according to GB / T 1040.3-2006. The test results are recorded in Table 1.

[0062] Table 1. Waterproofing, oxygen barrier properties, and mechanical properties of the composite membrane

[0063] <![CDATA[Cobb value (g / m 2 )]]> <![CDATA[Oxygen permeability (cm 3 / m 2 ·d·Pa)]]> Tensile strength (MPa) Elongation at break (%) Example 1 1.9 0.83 5.38 40.9 Example 2 2.0 0.89 5.34 42.1 Example 3 2.0 0.92 5.45 39.6 Example 4 2.2 0.94 5.21 43.0 Example 5 2.1 0.91 5.27 42.7 Comparative Example 1 2.6 1.13 5.35 41.3 Comparative Example 2 2.5 1.10 5.10 38.5 Comparative Example 3 2.9 1.27 5.06 37.8

[0064] As can be seen from Table 1, the composite membrane provided by the present invention has excellent waterproof, barrier and mechanical properties.

[0065] The only difference between Comparative Example 1 and Example 1 is that glutaraldehyde is not added in S1; the only difference between Comparative Example 2 and Example 1 is that neopentyl glycol diacrylate is not added in S1; the only difference between Comparative Example 3 and Example 1 is that glutaraldehyde and neopentyl glycol diacrylate are not added in S1. As can be seen from Table 1, glutaraldehyde and neopentyl glycol diacrylate can significantly improve the hygroscopicity and oxygen barrier properties of the composite membrane, while neopentyl glycol diacrylate can significantly improve the mechanical properties of the composite membrane.

[0066] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A single material high barrier recyclable composite film comprising a first PE film layer, a second PE film layer and a third PE film layer, characterized in that, The first PE film layer comprises the following components in parts by weight: 90-110 parts of low-density polyethylene, 5-10 parts of inorganic antibacterial agent, 10-15 parts of EVOH, 5-10 parts of glutaraldehyde, and 5-10 parts of neopentyl glycol diacrylate; The second PE film layer comprises the following components in parts by weight: 80-100 parts of metallocene polyethylene and 3-5 parts of organic antibacterial agent; The third PE film layer comprises the following components in parts by weight: 90-110 parts high-density polyethylene, 5-10 parts inorganic antibacterial agent, 10-15 parts EVOH, 5-10 parts glutaraldehyde, 5-10 parts neopentyl glycol diacrylate, and 3-5 parts lubricant. In the first PE film layer and the third PE film layer, the mass ratio of glutaraldehyde to neopentyl glycol diacrylate is 1:

1.

2. The single material high barrier recyclable composite film according to claim 1, wherein, The inorganic antibacterial agents in the first PE film layer and the third PE film layer each independently include one or more of silver oxide, zinc oxide, titanium dioxide, and zinc silicate.

3. The single material high barrier recyclable composite film according to claim 1, wherein, The organic antibacterial agent is Sandan oil.

4. The high-barrier recyclable composite membrane of a single material according to claim 1, characterized in that, The lubricant includes one or more of zinc stearate, calcium stearate, magnesium stearate, and paraffin wax.

5. The single-material high-barrier recyclable composite film according to claim 1, characterized in that, The thickness ratio of the first PE film layer, the second PE film layer, and the third PE film layer is 2:1:

1.

6. The method of claim 1 to 5, wherein the method is characterized by, Includes the following steps: S1. Mix low-density polyethylene, inorganic antibacterial agent, EVOH, glutaraldehyde and neopentyl glycol diacrylate, melt extrude and granulate to obtain the first PE film layer material; S2. Mix metallocene polyethylene and organic antibacterial agent, melt extrude and granulate to obtain the second PE film layer material; S3. Mix high-density polyethylene, inorganic antibacterial agent, EVOH, glutaraldehyde, neopentyl glycol diacrylate and lubricant, melt extrude and granulate to obtain the third PE film layer material; S4. The first PE film layer material, the second PE film layer material, and the third PE film layer material are co-extruded to obtain a high-barrier recyclable composite film.