A compostable composite packaging material structure having a matt effect

Abstract

The application provides a compostable composite packaging material structure with a matt effect, which comprises, from top to bottom, a matt modified PBS film layer, a kraft paper layer, a modified PBAT film layer and an adhesive layer sandwiched between the layers. The matt modified PBS film layer, the kraft paper layer and the modified PBAT film layer are attached together by a composite film forming technology. The matt modified PBS film layer is arranged as the atomized outer surface layer of the packaging material, and the modified PBAT film layer is arranged as the heat-sealed inner surface layer of the packaging material. The matt modified PBS film layer has high tensile strength, good printing adaptability and matt performance. The matt modified PBS film layer is combined with the food-grade kraft paper layer and the modified PBAT film layer which has excellent ductility, heat-sealing property and degradability. The properties of the film layers are complementary. The obtained packaging material has an environmentally friendly appearance and excellent packaging performance, achieves a natural matte surface effect, and is waterproof and oil-proof. No additional matte oil printing is required. The packaging material is degraded and decomposed through composting, realizes voluntary recycling, and significantly reduces the impact of packaging waste on the environment.

Description

Technical Field

[0001] This utility model relates to the field of biodegradable composite material technology, and in particular to a compostable composite packaging material structure with matting effect. Background Technology

[0002] Paper-plastic packaging is an important form of modern packaging material. While paper packaging is widely available, it suffers from poor water resistance and lacks heat-sealing properties. It typically requires lamination with plastic film or coating to achieve heat sealing. Furthermore, traditional paper-plastic packaging is difficult to recycle, and the composite structure contains non-degradable materials, causing serious environmental pollution upon disposal. Therefore, developing biodegradable paper-plastic packaging materials to replace traditional non-degradable packaging is of great significance in response to environmental policies.

[0003] While traditional lamination methods can achieve heat-sealing performance by covering the surface of kraft paper with heat-sealing materials, they are difficult to simultaneously achieve a natural matte finish that is waterproof, oil-resistant, and elegant, as well as internal printing protection and overall compostability. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a composite packaging material structure that retains the functionality and aesthetics of paper-plastic packaging, has a matte finish, and is compostable.

[0005] To achieve the above objectives, the technical solution provided by this utility model is as follows: a composite packaging material structure with a matte finish that is compostable, comprising, from top to bottom, a matte modified PBS film layer, a kraft paper layer, a modified PBAT film layer, and an adhesive layer sandwiched between the layers. The matte modified PBS film layer, the kraft paper layer, and the modified PBAT film layer are bonded together using a composite film-forming technology. The matte modified PBS film layer is configured as the atomized outer surface layer of the packaging material, and the modified PBAT film layer is configured as the heat-sealed inner surface layer of the packaging material.

[0006] Preferably, a printed layer is provided on the inner surface of the matte modified PBS film layer.

[0007] Preferably, the kraft paper layer is made of food-grade kraft paper.

[0008] Preferably, the kraft paper layer can be replaced with a coated natural cellulose film layer.

[0009] Furthermore, the coating material of the coated natural cellulose film layer is a PVDC coating, an EVOH coating, or an acrylic coating.

[0010] This invention combines a matte-modified PBS film layer with high tensile strength, good printability, and matte performance, but low elongation, with a waterproof and oil-resistant kraft paper layer and a modified PBAT film layer with excellent extensibility, heat-sealing properties, and biodegradability. The properties of each film layer are complementary, resulting in a packaging material that combines an environmentally friendly appearance with excellent packaging performance, achieving a natural matte finish without the need for additional matte printing. After use, this packaging material can be decomposed into carbon dioxide, water, and organic matter through composting, enabling voluntary recycling and significantly reducing the environmental impact of packaging waste. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the overall structure of the present invention. Figure 1 ;

[0012] Figure 2 This is a schematic diagram of the overall structure of the present invention. Figure 2 ;

[0013] Figure 3 This is a schematic diagram of the overall structure of the present invention. Figure 3 . Detailed Implementation

[0014] The present invention will be further described below with reference to specific embodiments:

[0015] Example 1:

[0016] like Figure 1-3 As shown in the figure, the composite packaging material structure with matte effect and compostability described in this embodiment includes, from top to bottom, a matte modified PBS film layer 1, a kraft paper layer 2, a modified PBAT film layer 3, and an adhesive layer 4 sandwiched between the layers. The matte modified PBS film layer 1, the kraft paper layer 2, and the modified PBAT film layer 3 are bonded together by a composite film forming technology. The matte modified PBS film layer 1 is set as the atomized outer surface layer of the packaging material, and the modified PBAT film layer 3 is set as the heat-sealed inner surface layer of the packaging material.

[0017] 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, with a melting point of 110 degrees Celsius, and its performance is close to that of 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 method for producing the modified matte PBS film layer described in this application utilizes a co-extrusion film production technology. The formulation consists of 20-60% PBS, 10-40% PLA, 0-30% PPC, 0-20% PBAT, 0-3% mica, 0-2% calcium carbonate, 0.5% wax, 0.5% coupling agent, 0.3% chain extender, 0.2% opening agent, 0.2% slip agent, and 0.2% antistatic agent. The modified matte PBS film layer provides a natural matte finish, eliminating the need for additional matte ink printing, while also exhibiting good printability. Reverse printing protects the ink layer, enhancing both safety and aesthetics. In this application, the modified matte PBS film layer is used as the outer surface layer.

[0018] The kraft paper layer 2, commonly characterized by light brown, yellowish-brown, and off-white colors, is made from plant fibers after lignin removal from wood pulp. It contains no substances harmful to the human body, making it safer and more hygienic than traditional plastic packaging. As a biodegradable food packaging material, kraft paper can be used as fertilizer after degradation, without releasing harmful gases or harming the environment. Kraft paper is stable, possessing properties such as moisture resistance, oil resistance, low-temperature resistance, and freshness preservation, making it widely used in aseptic packaging in the food and pharmaceutical fields. 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, without impacting the natural ecosystem, is easy to manufacture, relatively inexpensive, and can be easily recycled.

[0019] The modified PBAT film layer 34, made of polyhydroxy fatty acid (PBAT), is 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 high cost, limiting its application in membrane materials. Therefore, PBAT needs modification, primarily through blending, to improve its overall performance. The modified PBAT film layer 34 described in this application is made by modifying PBAT with PLA, PBS, PHA, PCL, PPC, PVA, and inorganic fillers. This modification improves the processing performance of PBAT, and the resulting film still exhibits excellent biodegradability. Its mechanical properties, barrier properties, and weather resistance are all enhanced, broadening its application range and fields to meet more diverse packaging needs. In this application, the modified PBAT film layer 34 is used as a heat-sealing layer.

[0020] The adhesive layer 4 is a polyurethane adhesive. The polyurethane adhesive has heat resistance and cold resistance, and can withstand the temperature requirements of bag making or boiling and steaming. It can also withstand the temperature requirements of low-temperature refrigeration or freezing (with a low embrittlement temperature). It should be able to withstand the erosion of the contents and various media in the environment, and should be non-toxic, odorless, have good fluidity and leveling properties, and have good adhesion to the composite materials used.

[0021] A printing layer 5 is provided on the inner surface of the matte modified PBS film layer 1, using a reverse printing process to prevent the ink layer from being eroded by friction and chemical media, thereby improving the packaging's aesthetics and safety.

[0022] The kraft paper layer 2 is made of food-grade oil-proof and waterproof kraft paper, and the kraft paper layer 2 can also be replaced with a coated natural cellulose film layer. The coating material of the coated natural cellulose film layer is PVDC coating, EVOH coating or acrylic coating.

[0023] Natural cellulose, commonly known as cellophane, is a highly transparent and glossy natural cellulose film made from dissolving pulp made from natural fibers such as cotton linters and chemically synthesized wood through an adhesive process. It is also called "regenerated cellulose film." The term "regenerated" does not mean reused; it refers to the cellulose film produced through the rearrangement of molecular chains in the adhesive process.

[0024] The production method of natural cellulose film (cellophane) differs from papermaking but is similar to that of rayon. It uses cotton linter dissolving pulp or refined chemical wood pulp with high α-cellulose content as raw material. Alkali cellulose is obtained through alkalization (18% sodium hydroxide), pressing, and pulverization. After aging, carbon disulfide is added to xanthate it into cellulose xanthate, which is then dissolved in sodium hydroxide solution to produce an orange-yellow cellulose viscose. This viscose is cured at 20–30°C, filtered to remove impurities and air bubbles, and then extruded through a narrow slit in a film-forming machine, flowing into a coagulation bath of a mixture of sulfuric acid and sodium sulfate to form a film (regenerated cellulose film). This film then undergoes washing, desulfurization, bleaching, desalting, softening (with glycerol and ethylene glycol, etc.), and coloring, before finally drying. While acids, alkalis, and carbon disulfide are used in the production process, the film is treated to remove all chemical residues.

[0025] The natural cellulose film, known as "cellophane," is: ① Biodegradable: Tests conducted by Zhejiang University of Commerce and Industry showed that "when buried for 45 days, the film severely disintegrated; upon excavation, it crumbled along with the soil, making it impossible to obtain a sample for degradation and weight loss testing"; ② Non-toxic and odorless, producing no thick smoke or foul odor when burned; ③ Excellent insulation (surface resistance 8.2 × 10⁷ Ω), static-free, dust-resistant, and highly printable; ④ Good air permeability: average oxygen permeability is 67.018 cc / ㎡.day; due to its cellulose composition, the film has capillary pores for air permeability, making it suitable for preserving fruits and vegetables; ⑤ High-temperature resistant: it remains undeformed after being held at 200℃ for 24 hours in an oven.

[0026] The natural cellulose film layer has a certain degree of air permeability and a large elongation. It is not fire-resistant but is heat-resistant, and can remain undeformed at temperatures above 190°C. It can be sterilized at high temperatures along with food in food packaging, which is very beneficial for the preservation and activity of food. It has strong resistance to oil, alkali and organic solvents. Air, oil, bacteria and water cannot easily pass through the natural fiber film layer. It has high oil barrier properties. Because it is made of natural fibers, it can absorb water and is easily decomposed during disposal. It does not generate static electricity, does not attract dust, and its high transparency makes the packaged goods clear at a glance. After applying a functional coating to the surface, it can adapt to more demanding packaging requirements.

[0027] The natural cellulose film layer may be a coated natural cellulose film layer, and the coated natural cellulose film layer may be coated with a PVDC coating, an EVOH coating, or an acrylic coating to enhance the water and oxygen barrier properties of the composite packaging material and adapt to more high-barrier packaging applications.

[0028] PVDC, commonly known as the "K layer," offers excellent barrier properties against moisture, oxygen, odors, and aromas under any temperature and humidity conditions. PVDC coatings provide the base film with secure 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 damaging the packaging due to moisture absorption. EVOH coatings offer superior oxygen barrier properties, effectively blocking carbon dioxide and preserving aroma. Acrylic acid's oxygen barrier properties fall between PVDC and dry EVOH, and it provides excellent printability, making it suitable for high-quality printing. Applying these high-barrier coatings to the base film significantly improves the freshness and aroma retention of food, extending its shelf life.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) Overall biodegradability: Each layer of the composite membrane structure is made of biodegradable materials. After the packaging is discarded, it can be composted and decomposed into carbon dioxide, water and organic matter, reducing environmental pollution. Compared with traditional paper-plastic composite packaging or laminated packaging, this composite membrane structure is completely compostable and meets international certification standards such as DIN EN13432, ASTM D6400, and OK COMPOSTABLE.

[0031] (2) The elegant matte appearance reduces printing costs: The matte modified PBS film layer 1 provides a natural matte effect, eliminating the need for additional matte printing, while also having good printability. The reverse printing can protect the ink layer, improving safety and aesthetics.

[0032] (3) Excellent waterproof, oil-proof and heat-sealing performance: The outer matte modified PBS film layer 1, the middle kraft paper layer 2 or the coated natural cellulose film layer all provide waterproof, oil-proof and certain water and oxygen barrier functions, and the inner modified PBAT film layer 3 provides heat-sealing performance and flexibility. The overall packaging is suitable for a variety of bag making and heat-sealing equipment.

[0033] (4) Stable structure and complementary performance: The multi-layer composite structure makes the properties of each layer of material complementary, and the overall mechanical strength, puncture resistance and oil resistance are improved, making up for the shortcomings of single-layer film.

[0034] (5) Advantages of composite process and wide range of applications: Compared with traditional lamination, this utility model adopts a composite film structure, which can combine the matte modified PBS film layer 1, the kraft paper layer 2 and the heat-sealing film layer into a whole material. The composite process can precisely control the firmness of the interlayer bonding, ensure the stability of the film layer and the reliability of processing, and is especially suitable for heavy-duty packaging and retort packaging; at the same time, it is easy to print ink layers on the inside, improve the safety and aesthetics of packaging, and has flexible functional combinations and a wider range of applications.

[0035] Table 1: Comparison of Single-Layer Thin Film Materials and Composite Thin Film Materials

[0036] Material Matting Modified PBS Kraft paper Modified PBAT Coated cellulose Kraft paper / modified PBAT Coated cellulose / kraft paper / modified PBAT Matte-modified PBS / kraft paper / modified PBAT Matte-modified PBS / coated natural cellulose / modified PBAT Typical values ​​of HC surface haze 50 90 20 5 90 90 98 98 Typical TC transmittance 88 30 80 92 30 30 30 30 Performance characteristics Printable, waterproof and oil-resistant White, non-waterproof, oil-proof Heat-sealing properties Excellent water and oxygen barrier White, non-waterproof, oil-proof Glossy finish, but not oil-resistant. Matte printing effect, waterproof and oil-resistant Printing matte finish, water-resistant, oxygen-resistant, waterproof, and oil-resistant

[0037] As shown in Table 1, this application has better printing matte and barrier properties than existing single-layer or composite film materials.

Claims

1. A compostable composite packaging material structure with matting effect, characterized in that: From top to bottom, the packaging material comprises a matte modified PBS film layer, a kraft paper layer, a modified PBAT film layer, and an adhesive layer sandwiched between the layers. The matte modified PBS film layer, the kraft paper layer, and the modified PBAT film layer are bonded together using a composite film-forming technology. The matte modified PBS film layer serves as the atomized outer surface layer of the packaging material, and the modified PBAT film layer serves as the heat-sealed inner surface layer of the packaging material.

2. The compostable composite packaging material structure with matting effect according to claim 1, characterized in that: A printed layer is provided on the inner surface of the matte-modified PBS film layer.

3. The compostable composite packaging material structure with matting effect according to claim 1, characterized in that: The kraft paper layer is made of food-grade kraft paper.

4. The compostable composite packaging material structure with matting effect according to claim 1, characterized in that: The kraft paper layer can be replaced with a coated natural cellulose film layer.

5. The compostable composite packaging material structure with matting effect according to claim 4, characterized in that: The coating material of the coated natural cellulose film layer is a PVDC coating, an EVOH coating, or an acrylic coating.

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