Novel high-barrier paper-plastic composite packaging material structure capable of being composted at home

Abstract

The utility model provides a novel high-barrier paper-plastic composite packaging material structure capable of composting at home, which comprises an outer functional layer, a middle barrier layer and an inner heat-sealing layer from top to bottom, adhesive layers are respectively clamped among the outer functional layer, the middle barrier layer and the heat-sealing layer, the outer functional layer comprises a cellulose membrane layer, and the cellulose membrane layer comprises a cellulose membrane layer. The middle barrier layer comprises a kraft paper layer and a first aluminized layer, the heat sealing layer comprises a second aluminized layer and a modified PBAT film layer, and all the layers are combined together through a composite technology. The high-barrier-property environment-friendly packaging material has excellent barrier property and biodegradability, the mechanical property of the degradable material is improved, all layers of materials complement each other, the complementary performance is different, and the high-barrier-property environment-friendly packaging material product capable of being composted at home is prepared. The packaging products can be converted into soil fertilizers, carbon dioxide and water through household compost after being consumed and discarded, and the packaging products have important significance on reduction of plastic garbage and environmental protection.

Description

Technical Field

[0001] This utility model relates to the field of biodegradable composite material technology, and in particular to a novel high-barrier paper-plastic composite packaging material structure that can be composted at home. Background Technology

[0002] In recent years, increased environmental awareness has led people to pay more attention to the harm of plastic pollution to the environment, and environmental policies in various countries are constantly being updated. my country recently proposed a "paper-for-plastic" policy in the environmental field. However, "paper-for-plastic" refers to using paper instead of plastic in situations where strong durability and water resistance are not required, such as supermarket shopping bags and takeout containers, replacing traditional plastic bags and containers to reduce plastic pollution.

[0003] In the flexible packaging sector, paper-plastic packaging combines paper and plastic, offering high sustainability and environmental friendliness. Traditional paper-plastic packaging materials consist of paper, non-degradable plastics, and other materials. Recycling traditional paper-plastic packaging is difficult; physical peeling methods are challenging and resource-intensive for thinner or more complex structures. Chemical separation methods are efficient but pose environmental and health risks. With biodegradable packaging materials becoming a popular research and application area, combining the environmentally friendly recyclability of paper with biodegradable plastics can effectively reduce environmental pollution and resource waste. Meanwhile, the pollution from leaks of heat-sealable packaging materials made from non-degradable plastics such as PP and PE combined with paper remains a major pollution problem that is currently unresolved.

[0004] Existing cellulose membranes have good gas barrier properties and printability, but their mechanical strength is insufficient. Kraft paper and PBAT films can improve their barrier properties through aluminizing, but single materials or simple composite materials cannot simultaneously achieve barrier properties, mechanical properties, and biodegradability. Currently, biodegradable packaging is only suitable for food packaging with medium to low barrier requirements, such as fried foods like potato chips and crunchy nuts, which have high barrier requirements. There is an urgent need for breakthroughs in new barrier technologies to expand the application of environmentally friendly packaging. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a new type of high-barrier paper-plastic composite packaging material structure that combines excellent barrier properties, mechanical properties and can meet the degradation requirements of multiple scenarios and is compostable at home.

[0006] To achieve the above objectives, the technical solution provided by this utility model is as follows: a novel high-barrier paper-plastic composite packaging material structure that can be composted at home, comprising, from top to bottom, an outer functional layer, a middle barrier layer, and an inner heat-sealing layer, with an adhesive layer sandwiched between the outer functional layer, the middle barrier layer, and the heat-sealing layer. The outer functional layer includes a cellulose film layer, the middle barrier layer includes a kraft paper layer and a first aluminized layer, and the heat-sealing layer includes a second aluminized layer and a modified PBAT film layer. The layers are bonded together by a composite process.

[0007] Preferably, the first aluminum plating layer is disposed at the lower part of the kraft paper layer.

[0008] Preferably, the second aluminum plating layer is disposed on the upper part of the modified PBAT film layer.

[0009] Preferably, the modified PBAT membrane layer can be replaced by a modified PBS membrane layer.

[0010] Preferably, a first PVDC coating is provided on the lower part of the cellulose membrane layer.

[0011] Preferably, the first PVDC coating can be replaced by an acrylic coating.

[0012] Preferably, a second PVDC coating is provided on the lower part of the kraft paper layer.

[0013] Furthermore, the second PVDC coating can be replaced by an acrylic coating.

[0014] Preferably, a printing layer is provided between the cellulose membrane layer and the adhesive layer.

[0015] The advantages of this utility model are: (1) Excellent barrier performance: The barrier performance of the composite material is significantly improved by the double-layer aluminum plating structure, which is suitable for packaging scenarios with high barrier requirements; (2) Biodegradability: The cellulose film layer, kraft paper layer and modified PBAT film layer are all biodegradable materials. The aluminum plating layer accounts for a small proportion and will not have a significant impact on the biodegradability of the composite material; (3) Improved mechanical properties of degradable materials: The kraft paper layer has tear resistance, tensile strength and tough wear resistance, and can withstand a certain impact. The modified PBAT film layer has excellent heat sealing and tensile properties, and can withstand greater pressure and tension. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the present invention. Figure 1 ;

[0017] Figure 2 This is a schematic diagram of the overall structure of the present invention. Figure 2 ;

[0018] Figure 3 This is a schematic diagram of the overall structure of the present invention. Figure 3 ;

[0019] Figure 4 This is a schematic diagram of the overall structure of the present invention. Figure 4 . Detailed Implementation

[0020] The present invention will be further described below with reference to specific embodiments: Example

[0021] like Figure 1-3 As shown in this embodiment, a novel high-barrier paper-plastic composite packaging material structure for home composting comprises, from top to bottom, an outer functional layer, a middle barrier layer, and an inner heat-sealing layer. An adhesive layer is sandwiched between the outer functional layer, the middle barrier layer, and the heat-sealing layer. The outer functional layer includes a cellulose film layer, the middle barrier layer includes a kraft paper layer and a first aluminized layer, and the heat-sealing layer includes a second aluminized layer and a modified PBAT film layer. The layers are bonded together using a solvent-free lamination process.

[0022] The cellulose membrane has good oxygen barrier properties and printability. It has strong resistance to oil, alkali and organic solvents. Air, oil, bacteria and water cannot easily pass through the cellulose membrane layer. It has high oil barrier properties and can absorb water and is easily decomposed during waste disposal.

[0023] The kraft paper layer is made of yellow or white kraft paper, which can be used as fertilizer after degradation without releasing harmful gases or harming the environment. Kraft paper is stable and possesses properties such as moisture resistance, oil resistance, low-temperature resistance, and freshness preservation, making it widely used in aseptic packaging for food and pharmaceuticals. While the surface of kraft paper is slightly rough, it has high toughness, tensile strength, and tear strength. In particular, kraft paper is considered a sustainable and environmentally friendly packaging solution—a perfect alternative for packaging designed to protect the environment. It decomposes easily in the natural environment in a short time, does not impact the natural ecosystem, is easy to manufacture, relatively inexpensive, and can be easily recycled.

[0024] The modified PBAT film layer uses polyhydroxy fatty acid (PBAT), a copolymer of butylene adipate (BT) and butylene terephthalate (BT). Using adipic acid (AA), terephthalic acid (PTA), and butanediol (BDO) as comonomers, it is a fully biodegradable plastic. It combines the characteristics of both PBA (polybutylene adipate) and PBT (polybutylene terephthalate), exhibiting good mechanical properties, high ductility and elongation at break, and excellent biodegradability. As a high-performance environmentally friendly material, PBAT can reduce petroleum resource consumption and alleviate "white pollution." Currently, the global PBAT market has strong demand, wide applications, high industry concentration, large potential market, and good industrialization prospects. Pure PBAT suffers from poor crystallinity, low melt strength, and cost, limiting its application in membrane materials. Therefore, PBAT needs modification, primarily through blending, to improve its overall performance. The modified PBAT film layer described in this utility model is made by modifying PBAT with PLA, PBS, PHA, PCL, PPC, PVA, inorganic fillers, and other materials. This can improve the processing performance of PBAT. The film material obtained after blending and modification still has excellent biodegradability, and its mechanical properties, barrier properties, and weather resistance are all improved, thus broadening its application range and fields and meeting more diversified packaging needs.

[0025] A first aluminum-plated layer and a second aluminum-plated layer are respectively disposed on the lower part of the kraft paper layer and the upper part of the modified PBAT film layer. The barrier performance is enhanced through the double-layer aluminum-plated structure design. The proportion of the first and second aluminum-plated layers in the overall composite structure is less than the threshold specified by relevant laws, which meets the standard for full biodegradability and therefore will not have a significant impact on the biodegradability of the composite material.

[0026] A first PVDC coating is provided at the bottom of the cellulose membrane layer; a second PVDC coating is provided at the bottom of the kraft paper layer; and a second aluminum plating layer is provided at the bottom of the second PVDC coating to further enhance the barrier properties of the kraft paper layer.

[0027] PVDC coating, commonly known as the "K layer," offers excellent barrier properties against moisture, oxygen, odors, and fragrances under any temperature or humidity conditions. It provides the base film with safe gas and moisture barrier properties, delaying food oxidation and spoilage, extending shelf life, and preventing the loss of aroma from the contents and the intrusion of unpleasant external odors. Moisture barrier properties prevent the contents from drying out and avoid damaging the original packaging due to moisture absorption. Even ordinary films with poor gas barrier properties can have their oxygen permeability reduced to around 5 cm³ (m²-24h-0.1 MPa) or even lower, and their moisture permeability reduced to around 10 g / (mm²-24h), after applying a PVDC coating.

[0028] The first PVDC coating can be replaced by an acrylic coating; the second PVDC coating can be replaced by an acrylic coating. The acrylic coating is used in plastic films mainly to obtain better heat-sealing properties, packaging mechanical properties, odor barrier properties, aesthetics, and stability. The finished film with the acrylic coating 1C has low haze and high gloss.

[0029] like Figure 4 As shown, the modified PBAT membrane layer can be replaced by a modified PBS membrane layer. PBS is a bio-based biodegradable plastic, specifically polyethylene glycol succinate. Its properties fall between those of PLA and PBAT. It exhibits good heat resistance, a melting point of 110 degrees Celsius, and properties close to polypropylene. However, pure PBS suffers from poor crystallinity and is prone to weathering and degradation, limiting its application in membrane materials. Therefore, PBS needs modification, primarily through blending, to improve its overall performance. The modified PBS membrane layer uses PBS as the main material, modified with PBAT, PLA, PHA, PCL, PPC, PVA, and inorganic fillers. This improves the processing performance of PBS, and the resulting membrane still possesses excellent biodegradability. PBS exhibits good biocompatibility and bioabsorbability. PBS has excellent mechanical properties and superior heat resistance after modification, overcoming the low heat resistance of other biodegradable plastics. PBS can degrade under conditions of contact with specific microorganisms, such as in home composting and soil.

[0030] As shown in Table 1, the composite film structure in this application has excellent barrier properties. The double-aluminized structure design, which combines an aluminized kraft paper layer and an aluminized modified PBAT film layer or an aluminized modified PBS film layer, significantly improves the barrier properties of the composite material and is suitable for packaging scenarios with high barrier requirements.

[0031] Furthermore, the cellulose membrane layer, kraft paper layer, modified PBAT membrane layer, or modified PBS membrane layer are all biodegradable materials. Even with a double-aluminized structure design to enhance barrier properties, the proportion of the aluminized layer in the composite material structure is less than the regulatory requirements for biodegradable packaging materials, thus still meeting the standard for full biodegradability. Specifically, the thickness and coverage of the aluminized layer are controlled to ensure that its proportion in the overall composite material is below the threshold of 1% stipulated by relevant regulations, thereby not significantly affecting the biodegradability of the composite material. In practical applications, after being acted upon by microorganisms in the natural environment, this composite material can degrade into water, carbon dioxide, and biomass within a specified time (e.g., within 180 days), without causing persistent environmental pollution. It meets international standards (such as EN 13432, ASTM D6400, etc.) and is suitable for fields with high environmental protection requirements, such as food packaging and daily necessities packaging.

[0032] While meeting the requirements for biodegradability and barrier properties, the composite material of this application also improves mechanical properties. The aluminized kraft paper has excellent tear resistance, tensile strength, and tough abrasion resistance, and can withstand certain impacts, further protecting the contents and adapting to long-distance transportation or repeated use. The aluminized PBAT has excellent heat-sealing and tensile properties, and can withstand greater pressure and tension.

[0033] The cellulose membrane layer has good printability, and a printing layer may also be provided between the cellulose layer and the adhesive layer.

Claims

1. A novel high-barrier paper-plastic composite packaging material structure that is compostable at home, characterized in that: From top to bottom, the layers are an outer functional layer, an intermediate barrier layer, and an inner heat-sealing layer. An adhesive layer is sandwiched between the outer functional layer, the intermediate barrier layer, and the heat-sealing layer. The outer functional layer includes a cellulose membrane layer, the intermediate barrier layer includes a kraft paper layer and a first aluminized layer, and the heat-sealing layer includes a second aluminized layer and a modified PBAT membrane layer. The layers are bonded together by a composite process.

2. The novel high-barrier paper-plastic composite packaging material structure for home composting according to claim 1, characterized in that: The first aluminum plating layer is disposed on the lower part of the kraft paper layer.

3. The novel high-barrier paper-plastic composite packaging material structure for home composting according to claim 1, characterized in that: The second aluminum plating layer is disposed on the upper part of the modified PBAT film layer.

4. The novel high-barrier paper-plastic composite packaging material structure for home composting according to claim 1 or 3, characterized in that: The modified PBAT membrane can be replaced by a modified PBS membrane.

5. The novel high-barrier paper-plastic composite packaging material structure for home composting according to claim 1, characterized in that: A first PVDC coating is provided on the lower part of the cellulose membrane layer.

6. The novel high-barrier paper-plastic composite packaging material structure for home composting according to claim 5, characterized in that: The first PVDC coating can be replaced by an acrylic coating.

7. The novel high-barrier paper-plastic composite packaging material structure for home composting according to claim 1, characterized in that: A second PVDC coating is provided on the lower part of the kraft paper layer.

8. The novel high-barrier paper-plastic composite packaging material structure for home composting according to claim 7, characterized in that: The second PVDC coating can be replaced by an acrylic coating.

9. The novel high-barrier paper-plastic composite packaging material structure for home composting according to claim 1, characterized in that: A printing layer is provided between the cellulose membrane layer and the adhesive layer.

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