Manufacturing process and preparation system of packaging material easy to recycle

Abstract

The invention discloses a manufacturing process and a preparation system of an easy-to-recycle packaging material. The manufacturing process at least comprises the following steps: S1, printing; s2, externally coating a protective layer; s3, die cutting; s4, gluing for the first time; s5, gluing for the second time; s6, gluing for the third time; s7, preheating before compounding; and S8, compounding and the like to finally form the packaging material. The preparation system is used for realizing the manufacturing process of the easy-to-recycle packaging material. According to the manufacturing technology, the laminating technology is adopted in the compounding process, the environment-friendly water-based hot sealing adhesive is adopted for bonding, a production place is small in smell, even free of peculiar smell and environmentally friendly, only one face (the back face) of the paper needs to be heated before compounding, the technology is simple, and cost is low. All the adhesives and the waterproof coating are made of environment-friendly water-based materials, and compared with traditional protective layers and adhesives made of plastics, the environment-friendly water-based waterproof coating has the advantages of being environmentally friendly, non-toxic, small in smell, easy to prepare, simple in component, capable of meeting food-grade use requirements and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of packaging materials, in particular to a manufacturing process and system of easy-to-recycle packaging materials. BACKGROUND

[0002] Tetra Pak is a composite paper aseptic packaging system developed by Tetra Pak, Sweden, which is mainly composed of paperboard, composite polyethylene and aluminum foil layer, can block light and oxygen pollution, prolong the shelf life of food and reduce the dependence on cold chain, so as to ensure that the packaging content can have a long shelf life without refrigeration and preservatives, which not only solves the challenge of product shelf life during long-distance transportation, but also avoids food waste.

[0003] The classic structure of the existing Tetra Pak packaging material is usually seven layers, from outside to inside: outer polyethylene, printing layer, paperboard, polyethylene (adhesive layer), aluminum foil, polyethylene (adhesive layer) and inner polyethylene. The ingenuity of Tetra Pak packaging material mainly lies in that the advantages of the three main materials are combined: paperboard: provides rigidity, structure and printability. Polyethylene (i.e. plastic): provides adhesion, moisture resistance and heat sealing function. Aluminum foil: provides absolute barrier to oxygen and light.

[0004] The preparation process of the existing Tetra Pak packaging material is as follows: First stage: raw material preparation: prepare paperboard roll, polyethylene particles, aluminum foil roll and ink; Second stage: printing: the paperboard roll is sent into the intaglio printing machine, and through accurate overprinting, the final bright-colored, clear-patterned trademarks, instructions and bar codes are formed, and after printing, the ink is quickly dried and solidified by hot air or ultraviolet irradiation; Third stage: compounding: completed by multi-head co-extrusion coating process, the specific process is as follows: First step: the printed paper and aluminum foil are bonded together by LDPE coating compounding to obtain a "paper / LDPE / aluminum foil" structure; Second step: EAA / heat-seal PE is co-extruded on the aluminum foil side to obtain a "paper / LDPE / aluminum foil / EAA / heat-seal PE" structure; Third step: LDPE is coated on the outside of the paper to protect the printing on the outside, and the final product "LDPE / paper / LDPE / aluminum foil / EAA / heat-seal PE" structure is obtained.

[0005] The above preparation process has at least the following defects: 1. The paperboard layer and the aluminum foil are strongly bonded by polyethylene (i.e. plastic), which is difficult to separate, or in other words, most of the fibers of the paperboard layer will adhere to the plastic after separation, which has defects such as recycling difficulty, low recycling rate, low reuse rate and serious resource waste; 2. The outer protective film on the outer surface of the cardboard layer is made of polyethylene, meaning the printing layer is wrapped in plastic. Although this provides waterproofing, it is a paper-plastic composite material, making separation difficult. Summary of the Invention

[0006] The purpose of this invention is to provide a manufacturing process and preparation system for easily recyclable packaging materials, which can at least solve one of the above-mentioned problems.

[0007] According to one aspect of the present invention, a manufacturing process for easily recyclable packaging material is provided, comprising at least the following steps: S1, printing: printing a pattern on the first end face of a cardboard layer to obtain a printed layer; S2, External protective layer: An environmentally friendly water-based waterproof coating is applied to the surface of the printed layer to obtain a protective layer, thereby forming a paper composite layer; S3. Die-cutting: Various lines or holes are formed on the paper composite layer using a die-cutting device; S4. First application of adhesive: Apply the first environmentally friendly water-based heat-sealing adhesive to the second end face of the cardboard layer using a local coating method to form a heat-sealing adhesive layer; S5. Second application of adhesive: Apply a second environmentally friendly water-based heat-sealing adhesive to the surface of the protective layer to form a longitudinal sealing adhesive layer; S6. Third application of adhesive: Apply a third environmentally friendly water-based heat-sealing adhesive to the surface of the protective layer to form a corner adhesive layer; S7. Preheating before lamination: Heating the heat-sealing adhesive layer formed in step S4; S8. Lamination: Press the paper composite layer after preheating in step S7 with the aluminum foil composite layer to form packaging material.

[0008] In some implementations, the protective layer formation step in step S2 is as follows: S201, First coating: First, apply the first environmentally friendly water-based waterproof coating to the surface of the printed layer; The first environmentally friendly water-based waterproof coating comprises the following components by weight percentage: Polyacrylate, 30-40%; Water, 61-65%; Wetting agent, 0.1-1%; Defoamer, 0.1-1%; S202, Second coating: Apply a second environmentally friendly water-based waterproof coating to the surface of the first environmentally friendly water-based waterproof coating; The second environmentally friendly water-based waterproof coating comprises component B and component A in a mixing ratio of 3:100, wherein component A comprises the following components by weight percentage: Waterborne polyolefins, or 25-30%; Water, 70-75%; wetting agent, 0.2-1%; antifoaming agent, 0.2-1%; ammonia, 0.1-0.5%; Component B is a curing agent, and the curing agent is a polycarbodiimide.

[0009] In some embodiments, the first environmentally friendly water-based heat seal adhesive in step S4 comprises the following components in percentage by weight: water-based polyolefin, 40-45%; water, 50-60%; wetting agent, 0.1-1%; antifoaming agent, 0.1-1%.

[0010] In some embodiments, the second environmentally friendly water-based heat seal adhesive in step S5 and the third environmentally friendly water-based heat seal adhesive in step S6 are the same as the components of the first environmentally friendly water-based heat seal adhesive.

[0011] In some embodiments, the second environmentally friendly water-based heat seal adhesive in step S5 and the third environmentally friendly water-based heat seal adhesive in step S6 are the same in components, specifically comprising the following components in percentage by weight: polyacrylate, 35-40%; water, 60-65%; wetting agent, 0.1-1%; antifoaming agent, 0.1-1%.

[0012] In some embodiments, the second environmentally friendly water-based heat seal adhesive in step S5 and the third environmentally friendly water-based heat seal adhesive in step S6 are the same in components, specifically comprising the following components in percentage by weight: water-based polyolefin, 25-30%; water, 65-75%; wetting agent, 0.1-1%; antifoaming agent, 0.1-1%; ammonia, 0.1-1%.

[0013] In some embodiments, the wetting agent is alkyl phenol polyethylene glycol phosphate, and the antifoaming agent is water-soluble acrylic resin.

[0014] In some embodiments, the partial coating manner in step S4 is specifically: forming an outer peripheral coating layer by coating the first environmentally friendly water-based heat seal adhesive around the second end face of the paperboard layer; forming an intermediate coating layer by coating the first environmentally friendly water-based heat seal adhesive in the middle region of the second end face of the paperboard layer; the intermediate coating layer is distributed in a plurality of points or a grid shape.

[0015] In some embodiments, the aluminum foil composite layer comprises, from inside to outside, a second plastic layer, an EAA layer, an aluminum foil layer, and a first plastic layer.

[0016] According to another aspect of the present application, there is also provided a system for preparing the recyclable packaging material, for implementing the above-mentioned manufacturing process of the recyclable packaging material, the system comprising, in sequence along the conveying direction of the film material, a printing device, a first coating device, a die-cutting device, a second coating device, a third coating device, a fourth coating device, a heating device, a pressing device, and an aluminum foil composite device for forming the aluminum foil composite layer. The printing device is configured to form a printing layer on the first end face of the paperboard layer. The first coating device is configured to form a protective layer on the printing layer. The die-cutting device is configured to form one or more of a crease, a line, or a hole on the paper composite layer. The second coating device is configured to form a heat-seal adhesive layer on the second end face of the paperboard layer. The second coating device is configured to form a longitudinal seal adhesive layer on the surface of the paper composite layer. The third coating device is configured to form a corner adhesive layer on the surface of the paper composite layer. The heating device is configured to heat the heat-seal adhesive layer on the back of the paper composite layer. The pressing device is configured to guide and press the paper composite layer conveyed from the heating device and the aluminum foil composite layer conveyed from the aluminum foil composite device, so as to form the packaging material.

[0017] The present application has the following advantages: 1. The present application provides a manufacturing process of a recyclable packaging material with a novel structure, which adopts a modularization + separation structure, and the aluminum foil composite layer and the paper composite layer are connected by the environmentally-friendly water-based heat-seal adhesive layer, and the heat-seal adhesive layer is distributed in a dot or grid manner on the back of the paper composite layer (the side connected to the aluminum foil composite layer), which makes the paper composite layer and the aluminum foil composite layer separable, i.e., after the product made of the packaging material is used up, the paper composite layer on the surface can be easily and quickly torn off manually, which is convenient for manual recycling and automatic recycling, and the recycling rate is high, which is convenient for recycling, recycling, and recycling, and the aluminum foil composite layer (since there are few paper fibers adhered to the aluminum foil composite layer after separation) can be more easily recycled and processed.

[0018] 2. The outer protective layer on the outer surface of the paperboard layer adopts an environmentally-friendly water-based waterproof coating, which has low separation difficulty and high environmental protection.

[0019] 3. The composite process of the present invention is carried out by pressing, and environmentally friendly water-based heat-sealing adhesive is used for bonding. The production site has little or no odor, which is environmentally friendly. Moreover, only one side (back side) of the paper needs to be heated before lamination. The process is simple and low cost.

[0020] 4. The packaging material of this invention fully retains the aseptic filling technology of Tetra Pak in terms of material usage and preservation principle, using aluminum foil layer to block oxygen and light, and using plastic inner coating (second plastic layer) for sealing and moisture prevention, etc. However, it fundamentally subverts the traditional structure represented by Tetra Pak in terms of the composite method and the formation of the outermost protective layer. This allows the packaging material of this invention to be easily separated by hand by tearing after use, which accounts for at least 75% of the packaging material, thereby achieving the purpose of recycling paper materials, and it is also environmentally friendly.

[0021] 5. All adhesives and waterproof coatings of this invention are made of environmentally friendly water-based materials. Compared with traditional methods that use plastic as a protective layer and adhesives, they have many advantages such as being environmentally friendly and non-toxic, having little odor, being easy to formulate, having simple ingredients, and meeting food-grade requirements. Attached Figure Description

[0022] Figure 1 This is a simplified flowchart of the manufacturing process of the easily recyclable packaging material of the present invention; Figure 2 This is a simplified framework diagram of the recyclable packaging material preparation system of the present invention; Figure 3 This is a three-dimensional structural diagram of the pressing device of the present invention; Figure 4 for Figure 3 A three-dimensional structural diagram of the pressing device, omitting some structural elements; Figure 5 for Figure 4 A side view of the pressing device is shown. Figure 6 An exploded structural diagram of one type of packaging box product manufactured using the recyclable packaging material manufacturing process of the present invention; Figure 7 A simplified structural diagram of one type of packaging material manufactured using the recyclable packaging material manufacturing process of the present invention; Figure 8 for Figure 7 The diagram shows a further detailed structural representation of the packaging material. Figure 9 This is a schematic diagram showing the distribution of adhesive after the front side of the paper composite layer of the present invention has been coated. Figure 10 This is a schematic diagram of the first distribution of adhesive after the reverse side of the paper composite layer of the present invention is coated. Figure 11 This is a schematic diagram showing a second distribution of adhesive after the reverse side of the paper composite layer of the present invention is coated.

[0023] Figures 1-11 Figure labels in the diagram: 1-Paper composite layer; 2-Aluminum foil composite layer; 3-Heat-sealing adhesive layer; 4-Longitudinal sealing adhesive layer; 5-Corner adhesive layer; 11-Paperboard layer; 12-Printed layer; 13-Protective layer; 21-First plastic layer; 22-Aluminum foil layer; 23-Second plastic layer; 24-EAA layer; 31-Outer peripheral coating layer; 32-Intermediate coating layer; 000-Frame; 100-Printing device; 200-First coating device; 300-Die-cutting device; 400-Second coating device; 500-Third coating device; 600-Fourth coating device; 700-Pressing device; 800-Heating device; 900-Aluminum foil laminating device; 1000-Wrapping device; 701-First guide roller; 702-Second guide roller; 703-Laminated roller A; 704-Laminated roller B; 705-Pressure regulating mechanism; 705a-Pressure regulating drive; 705b-Swing arm. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings.

[0025] Figures 1-11 The illustration schematically shows the manufacturing process of an easily recyclable packaging material according to one embodiment of the present invention.

[0026] like Figure 1 As shown, the manufacturing process of this easily recyclable packaging material includes at least the following steps: S1, printing: printing a pattern on the first end face of the cardboard layer 11 to obtain the printed layer 12; S2, outer protective layer 13: an environmentally friendly water-based waterproof coating is applied to the surface of the printed layer 12 to obtain the protective layer 13, thereby forming the paper composite layer 1; S3. Die-cutting: The die-cutting device 300 forms one or more of the following on the paper composite layer 1: creases (e.g., indentations b), lines (e.g., tear lines), or holes (e.g., straw holes a). Figure 9 As shown; S4. First application of adhesive: Apply a first environmentally friendly water-based heat-sealing adhesive to the second end face of the cardboard layer 11 using a partial coating method to form a heat-sealing adhesive layer 3, such as... Figure 10 or Figure 11 As shown; S5. Second application of adhesive: Apply a second environmentally friendly water-based heat-sealing adhesive to the surface of the protective layer 13 to form the longitudinal sealing adhesive layer 4, such as... Figure 9 As shown; S6. Third application of adhesive: Apply a third environmentally friendly water-based heat-sealing adhesive to the surface of the protective layer 13 to form the corner adhesive layer 5, such as... Figure 9 As shown; S7. Preheating before lamination: Heating the heat-sealing adhesive layer 3 formed in step S4; S8. Lamination: Press the paper composite layer 1, which has been preheated in step S7, with the aluminum foil composite layer 2 to form a packaging material.

[0027] Preferably, the packaging material generated in step S8 can be directly used in online production, such as directly entering the sterilization workshop or filling workshop, or it can proceed to step S9: S9. Rewinding: Rewinding the packaging material. Rewound materials are easier to transport.

[0028] This invention also discloses a preparation system, wherein the above process is carried out through the following preparation system, specifically, as follows: Figures 2-5 As shown, the preparation system includes a printing device 100, a first coating device 200, a die-cutting device 300, a second coating device 400, a third coating device 500, a fourth coating device 600, a heating device 800, a pressing device 700, and a winding device 1000 arranged sequentially along the film material conveying direction, as well as an aluminum foil composite device 900 for forming the aluminum foil composite layer 2. The printing apparatus 100 is used to form a printing layer 12 on the first end face of the cardboard layer 11; The first coating apparatus 200 is used to form a protective layer 13 on the printed layer 12; Die-cutting device 300 is used to form indentations b, tear lines, or straw holes a on the paper composite layer 1; The second coating device 400 is used to form a longitudinal sealing adhesive layer 3 on the second end face of the paperboard layer 11 (i.e., the back side of the paper composite layer 1); The third coating apparatus 500 is used to form a longitudinal sealing adhesive layer 4 on the surface of the paper composite layer 1 (i.e. the front side of the paper composite layer 1); The fourth coating apparatus 600 is used to form a corner adhesive layer 5 on the surface of the paper composite layer 1 (i.e. the front side of the paper composite layer 1); Heating device 800 is used to heat the heat-sealing adhesive layer 3 on the back of the paper composite layer 1; The pressing device 700 is used to introduce and press the paper composite layer 1 conveyed from the heating device 800 and the aluminum foil composite layer 2 conveyed from the aluminum foil composite device 900 to form packaging material, and the winding device 1000 is used to wind up the packaging material.

[0029] Preferably, the pressing device 700 includes a frame 000 and a first guide roller 701, a second guide roller 702, a composite roller A703, and a composite roller B704 mounted on the frame 000. The first guide roller 701 is used to guide the aluminum foil composite layer 2 conveyed from the aluminum foil composite device 900 into the composite roller A703, and the second guide roller 702 is used to guide the paper composite layer 1 conveyed from the heating device 800 into the composite roller B704. Under the combined action of the composite roller A703 and the composite roller B704, packaging material is obtained.

[0030] Preferably, the pressing device 700 further includes a pressure adjusting mechanism 705, which is mounted on the frame 000 and cooperates with the composite roller B704 to adjust the pressing force between the composite roller B704 and the composite roller A703.

[0031] As a further preferred embodiment, the pressure regulating mechanism 705 includes a pressure regulating drive 705a and a swing arm 705b. The swing arm 705b is movably mounted on the frame 000. Both ends of the composite roller B704 are rotatably mounted on the swing arm 705b. The pressure regulating drive 705a is mounted on the frame 000 and its driving end is hinged to the swing arm 705b. Under the drive of the pressure regulating drive 705a, the composite roller B704 can move away from or closer to the composite roller A703.

[0032] Preferably, it also includes a control device, which is electrically connected to electrical components used to drive the operation of each device, specifically one or more PLC controllers.

[0033] Regarding other devices, the printing device 100, die-cutting device 300, second coating device 400, third coating device 500, and fourth coating device 600 adopt existing technology devices, and their specific structures will not be described in detail here. The first coating device 200 adopts a commonly available roller coating device, and after coating, it needs to be dried in a drying oven. The heating device 800 can be a heating lamp set directly above the pressing device 700 and corresponding to the first guide roller 701. It achieves heating by irradiating the heat-sealing adhesive layer 3 on the back of the paper composite layer 1, which facilitates the subsequent bonding of the paper composite layer 1 with the aluminum foil composite layer 2. The aluminum foil bonding device 900 can adopt an existing multi-head co-extrusion coating device, or it can adopt other bonding methods that can form plastic layers on both sides of the aluminum foil (such as sandwich coating process, heat bonding process, etc.), and finally form an independent aluminum foil composite layer 2.

[0034] Preferably, the steps for forming the protective layer in step S2 are as follows: S201, First coating: First, apply the first environmentally friendly water-based waterproof coating to the surface of the printed layer 12; The first environmentally friendly water-based waterproof coating comprises the following components by weight percentage: Polyacrylate, 35-40% Water, 60-65%; Wetting agent, 0.1-1%; Defoamer, 0.1-1%; S202, Second coating: Apply a second environmentally friendly water-based waterproof coating to the surface of the first environmentally friendly water-based waterproof coating; The second environmentally friendly water-based waterproof coating comprises component B and component A in a mixing ratio of 3:100, wherein component A comprises the following components by weight percentage: Waterborne polyolefin, 25-30%; Water, 70-75%; Wetting agent, 0.2-1%; Defoamer, 0.2-1%; Ammonia solution, 0.1-0.5%; Component B is a curing agent, which is polycarbodiimide.

[0035] As a further preferred embodiment, the first environmentally friendly water-based waterproof coating comprises the following components by weight percentage: polyacrylate, 38%; water, 61%; wetting agent, 0.5%; and defoamer, 0.5%.

[0036] As a further preferred embodiment, component A of the second environmentally friendly water-based waterproof coating comprises the following components by weight percentage: water-based polyolefin, 28%; water, 70.5%; wetting agent, 0.8%; defoamer, 0.2%; and ammonia, 0.5%.

[0037] The defoamer is preferably a water-soluble acrylic resin, and the wetting agent is preferably an alkylphenol polyethylene glycol phosphate.

[0038] The functions of each component in the above-mentioned environmentally friendly water-based waterproof coating are as follows: The core functions of the first environmentally friendly water-based waterproof coating are "priming" and "sealing." Polyacrylate, a film-forming substance, possesses excellent adhesion, flexibility, transparency, and film-forming properties. Primarily used as a substrate sealant, it addresses the issue of porous and fibrous cardboard surfaces. Directly applying subsequent coatings would lead to excessive paint penetration, unevenness, and high consumption. This layer of polyacrylate quickly penetrates and fills the micropores on the cardboard surface, forming a continuous, dense, and smooth underlying film. This not only prevents excessive penetration of subsequent coatings but also enhances the adhesion between the entire coating system and the cardboard substrate, preventing delamination. Wetting agents reduce the surface tension of the coating, allowing it to spread better on the cardboard surface and avoiding coating defects such as "fisheyes" and "pinholes," ensuring a uniform and complete coating. Defoamers quickly break and suppress bubbles, preventing pinholes in the dried coating, which would affect its density and waterproofness.

[0039] The second layer of environmentally friendly water-based waterproof coating is the "functional surface" of the entire system, its core function being to provide excellent water resistance and chemical stability. Water-based polyolefin is the main film-forming material of the second layer, possessing extremely excellent water resistance, chemical resistance, and moisture-proof properties. Unlike the polarity of cardboard and polyacrylate, polyolefin is non-polar, giving it a natural barrier against water, oil, and grease. A wetting agent ensures the second layer coating can perfectly level and spread on the first layer (polyacrylate) coating, avoiding interface defects. An antifoaming agent ensures a defect-free surface layer. Ammonia water is used as a pH adjuster and stabilizer, neutralizing acidic groups in the resin and preventing flocculation or clumping during storage, thus ensuring the stability of the coating system. After application, the ammonia water evaporates, restoring the coating to a stable state. Polycarbodiimide, as a crosslinking agent and anti-hydrolysis agent, has highly reactive functional groups (-N=C=N-) that can react with carboxyl groups (-COOH) commonly found in waterborne resins. Both polyacrylates and waterborne polyolefins typically contain carboxyl groups in their molecular chains. Polycarbodiimide can crosslink with these carboxyl groups to form a three-dimensional network structure, achieving the following effects: significantly improved water resistance: crosslinking makes the coating network more compact, making it harder for water molecules to penetrate; enhanced hydrolysis resistance: by consuming easily hydrolyzed carboxyl groups, it fundamentally improves the long-term stability of the coating in humid and hot environments, preventing the coating from degrading, whitening, or losing strength due to hydrolysis; high mechanical strength: crosslinking improves the coating's hardness, abrasion resistance, and anti-blocking properties.

[0040] The purpose and advantages of using two coatings are: 1. Functional layering, each with its own role: The core task of the first coating of environmentally friendly water-based paint is "adhesion". Polyacrylate has excellent adhesion to polar substrates (cardboard) and polar pigments (inks for printing patterns). It acts like "double-sided tape", firmly gripping the cardboard layer on one side and providing an ideal, flat construction platform for the second coating on the other side. The core task of the second coating is "protection". Water-based polyolefin + polycarbodiimide provides top-notch water resistance, moisture resistance, grease resistance and chemical resistance, directly facing the challenges of the external environment. 2. Optimize production process and performance: (1) Avoid the risk of "demulsification": If polycarbodiimide is directly added to the base coat, it will react violently with the carboxyl groups of the polyacrylate in the base coat, causing the coating to thicken rapidly, gel or even clump (demulsification), making it impossible to apply. Applying it in two coats and adding the curing agent only in the second coat perfectly avoids this production process disaster; (2) Achieve interfacial crosslinking: In the second coat, polycarbodiimide not only crosslinks with its own polyolefin resin, but also partially penetrates into the base coat and crosslinks with the polyacrylate in the base coat. This forms a strong "interpenetrating network" interfacial layer between the base coat and the top coat, which greatly enhances the interlayer adhesion and avoids the risk of peeling between layers in a humid environment; (3) Ensure coating quality: After the first coat is dried, a solid base is formed. The second coat is applied on top of it, which can effectively control the amount of coating and obtain a uniform, defect-free, high-quality top coat. If a thick coat is applied at once, problems such as sagging, uneven drying, and high internal stress are likely to occur.

[0041] 3. Economy and reliability: (1) Cost optimization: Polyacrylate is usually cheaper than water-based polyolefin. First, use cost-effective materials for bottom sealing and bonding, and then use materials with better performance but possibly more expensive for thin functional surface layer. This can control the overall cost while ensuring performance. (2) Increased reliability: The two-layer structure is equivalent to setting up two waterproof defenses. Even if there are extremely small defects in the surface layer (such as pinholes caused by dust), the bottom layer can still serve as an effective barrier to prevent moisture from directly and quickly penetrating into the cardboard, which greatly improves the reliability and safety of the packaging.

[0042] Preferably, the first environmentally friendly water-based heat sealant in step S4 comprises the following components by weight percentage: Waterborne polyolefin, 40-45%; Water, 50-60%; Wetting agent, 0.1-1%; Defoamer, 0.1-1%.

[0043] As a further preferred embodiment, the first environmentally friendly waterborne heat sealant comprises the following components by weight percentage: waterborne polyolefin, 40%; water, 59%; wetting agent, 0.5%; and defoamer, 0.5%.

[0044] Therefore, the functions of each component in the first environmentally friendly water-based heat sealant are as follows: Water-based polyolefin is the main film-forming and adhesive substance in this formulation. A 40% content is a relatively high solid content, which means: good initial tack: after coating, the moisture evaporates quickly, and the polymer particles can rapidly form initial tack; high final bonding strength: it can form a thicker, denser film, providing good cohesive strength. This type of water-based polyolefin (especially maleic anhydride-grafted type) has good wettability and adhesion to various difficult-to-bond materials (such as PP, PE, PET, metals, etc.), mainly through physical anchoring and intermolecular forces (van der Waals forces). (Huali) achieves adhesion; alkylphenol polyethylene glycol phosphate acts as a wetting agent to enhance adhesion, reducing the surface tension of the adhesive and allowing it to spread better on the surface of the bonded materials and penetrate into the micropores of the material surface. This not only increases the bonding area but also generates stronger mechanical interlocking forces, which is especially important for non-polar plastics (such as PP and PE); water-soluble acrylic resin is used as a defoamer to effectively ensure the integrity of the adhesive film and prevent the formation of bubbles during production and coating. Bubbles can cause defects in the cured adhesive film, forming stress concentration points, leading to a significant decrease in adhesive strength and poor sealing performance. Water, as an environmentally friendly carrier in this formulation, is safe, environmentally friendly, and low-cost. By adjusting the water content, the viscosity and coating performance of the adhesive can be controlled.

[0045] Preferably, the second environmentally friendly water-based heat sealant in step S5 and the third environmentally friendly water-based heat sealant in step S6 can have the same or different components as the first environmentally friendly water-based heat sealant.

[0046] For example, the second and third environmentally friendly water-based heat sealants in step S5 have the same composition, specifically including the following components by weight percentage: Polyacrylate, 35-40%; Water, 60-65%; Wetting agent, 0.1-1%; Defoamer, 0.1-1%.

[0047] As a further preferred embodiment, the second and third environmentally friendly water-based heat sealants specifically comprise the following components by weight percentage: polyacrylate, 38%; water, 61%; wetting agent, 0.5%; and defoamer, 0.5%.

[0048] Therefore, the functions of each component in the second and third environmentally friendly water-based heat sealants are as follows: Polyacrylate, as a heat-sensitive adhesive matrix, has a specific glass transition temperature: At room temperature: The polymer film is a hard, non-sticky solid; under heating conditions (e.g., 90-150°C): the polymer chains gain sufficient energy to begin moving, and the material transitions from a glassy state to a highly elastic state, becoming soft, molten, and extremely viscous; under pressure: this molten, viscous surface rapidly wets, diffuses, and entangles with another contact surface (usually a similar film), forming a tight contact; after cooling: the polymer chains are "frozen" again, reforming into a solid, thus creating a strong seal between the two interfaces. The functions of the other components are consistent with those of the first environmentally friendly water-based heat sealant and will not be elaborated here.

[0049] Preferably, the second and third environmentally friendly water-based heat sealants in step S5 have the same composition, specifically including the following components by weight percentage: Waterborne polyolefin, 25-30%; Water, 65-75%; Wetting agent, 0.1-1%; Defoamer, 0.1-1%; Ammonia solution, 0.1-1%.

[0050] The functions of each component in the above formula are as follows: Waterborne polyolefins: These are heat-sensitive adhesive resins, and their main functions are: Film-forming properties: After the water evaporates, the polymer particles aggregate into a continuous, transparent, and high-strength dry adhesive film.

[0051] Thermal activation: This polyolefin is designed to have a specific glass transition temperature or softening point. At room temperature, it is hard and non-sticky. When heated to a set temperature (e.g., 80-130°C), the polymer chain mobility increases, the material transitions from a glassy state to a highly elastic state, softens, melts, and becomes extremely viscous.

[0052] Adhesion and sealing: Under pressure, this molten viscous substance wets the surface of the substrate to be bonded and diffuses and entangles with the substrate or a similar adhesive film on the other side, forming a strong seal after cooling.

[0053] Ammonia is used as a pH adjuster and stabilizer.

[0054] The function of wetting agents is to reduce surface tension and improve spreadability.

[0055] The purpose of defoamers is to prevent and eliminate bubbles.

[0056] Water is used as a dispersion medium and viscosity modifier.

[0057] As a further preferred embodiment, the second and third environmentally friendly water-based heat sealants specifically comprise the following components by weight percentage: water-based polyolefin, 28%; water, 70.5%; wetting agent, 0.8%; defoamer, 0.2%; and ammonia, 0.5%.

[0058] The defoamers used in the above formulations are preferably water-soluble acrylic resins, and the wetting agents are preferably alkylphenol polyethylene glycol phosphates.

[0059] Preferably, the CAS number for the waterborne polyolefin is 308070-21-5; the CAS number for the polyacrylate is 9003-01-4; and the CAS number for the ammonia is 1336-21-6. The wetting agent is alkylphenol polyethylene glycol phosphate, with CAS number 3013-94-3; the defoamer is water-soluble acrylic resin, with CAS number 25767-39-9; and the CAS number for polycarbodiimide is 151-51-9.

[0060] It should be noted that, in order to achieve efficient online continuous production, the environmentally friendly water-based coating and water-based heat sealant of this invention need to be dried after coating, which can be achieved by means of a drying oven or the like.

[0061] The local coating method in step S4 is as follows: An outer peripheral coating layer 31 is formed by coating the periphery of the second end face of the cardboard layer 11 with a first environmentally friendly water-based heat sealant. An intermediate coating layer 32 is formed by applying a first environmentally friendly water-based heat-sealing adhesive to the middle area of ​​the second end face of the cardboard layer 11; like Figure 10 and Figure 11 As shown, the intermediate coating layer 32 can be distributed in a multi-point or grid pattern.

[0062] Preferably, the aluminum foil composite layer 2 includes a second plastic layer 23, an EAA layer 24, an aluminum foil layer 22, and a first plastic layer 21 arranged sequentially from the inside out. The second plastic layer 23 is mPE (metallocene polyethylene), the first plastic layer 21 is LDPE (low-density polyethylene), and the aluminum foil layer 22 and the second plastic layer 23 are bonded together using ethylene-acrylic acid copolymer (EAA), thus forming an EAA layer 24 between the aluminum foil layer 22 and the second plastic layer 23.

[0063] like Figures 6-8 As shown, the composition and function of the packaging material obtained by the manufacturing process of the easily recyclable packaging material of the present invention are as follows: The first layer is the protective layer 13, which is formed on the outermost layer of the packaging material by coating with food-grade environmentally friendly water-based paint, and plays a role in protecting the printed pattern, waterproofing, and wear resistance. The second layer is the printing layer 12, which serves to enhance the aesthetics and pattern layer; The third layer is a cardboard layer 11, preferably made of natural kraft paper, which provides rigidity, structure and printability to the packaging material; The fourth layer is the heat-sealing adhesive layer 3, which is a local coating obtained by local application of food-grade environmentally friendly water-based adhesive, and serves to bond the aluminum foil composite layer 2 and the paper composite layer 1. The fifth layer is the first plastic layer 21, which serves as a waterproof seal; The sixth layer is aluminum foil, which serves to block light from entering the beverage; The seventh layer is the second plastic layer 23. This plastic layer comes into direct contact with beverages and serves to package them.

[0064] The advantages of the manufacturing process of the easily recyclable packaging material of this invention compared to existing technologies are as follows: 1. This invention provides a novel manufacturing process for easily recyclable packaging materials. It employs a modular and separable structure, where the modular aluminum foil composite layer 2 and paper composite layer 1 are bonded together by an environmentally friendly water-based heat-sealing adhesive layer 3. The heat-sealing adhesive layer 3 is locally distributed on the back of the paper composite layer 1 (the side connected to the aluminum foil composite layer 2) in a dotted or grid pattern. This allows the paper composite layer 1 and aluminum foil composite layer 2 to be separated. After use, the paper composite layer 1 can be easily and quickly peeled off manually. This facilitates not only manual recycling but also automated recycling processes, resulting in convenient recycling, high recycling rates, and easy reuse and recycling. It also ensures that the aluminum foil composite layer 2 (due to minimal paper fibers adhering to it after separation) can be more easily recycled.

[0065] 2. The outer protective layer 13 on the outer surface of the cardboard layer adopts an environmentally friendly water-based waterproof coating, which is easy to separate and has strong environmental protection properties.

[0066] 3. The composite process of the present invention is carried out by pressing, and environmentally friendly water-based heat-sealing adhesive is used for bonding. The production site has little or no odor, which is environmentally friendly. Moreover, only one side (back side) of the paper needs to be heated before lamination. The process is simple and low cost.

[0067] 4. The packaging material of the present invention fully retains the aseptic filling technology of Tetra Pak in terms of material use and preservation principle, and uses key technologies such as aluminum foil layer 22 to block oxygen and light, and plastic inner coating (second plastic layer 23) for sealing and moisture prevention. However, it fundamentally subverts the traditional structure represented by Tetra Pak in terms of the composite method and the formation of the outermost protective layer 13. This allows the packaging material of the present invention to easily separate at least 75% of the paper in the packaging box by hand after use, thereby achieving the purpose of recycling paper materials, and it is also environmentally friendly.

[0068] 5. All adhesives and waterproof coatings of this invention are made of environmentally friendly water-based materials. Compared with traditional methods that use plastic as a protective layer and adhesives, they have many advantages such as being environmentally friendly and non-toxic, having little odor, being easy to formulate, having simple ingredients, and meeting food-grade requirements.

[0069] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A manufacturing process for an easily recyclable packaging material, characterized in that, At least the following steps are included: S1. Printing: Print a pattern on the first end face of the cardboard layer (11) to obtain the printed layer (12); S2, External protective layer (13): Environmentally friendly water-based waterproof coating is applied to the surface of the printed layer (12) to obtain a protective layer (13), thereby forming a paper composite layer (1); S3. Die-cutting: forming one or more of the following on the paper composite layer (1) by means of a die-cutting device (300): creases, lines or holes; S4, First coating: Apply the first environmentally friendly water-based heat sealant to the second end face of the cardboard layer (11) using a local coating method to form a heat sealant adhesive layer (3); S5. Second application of adhesive: Apply a second environmentally friendly water-based heat sealant to the surface of the protective layer (13) to form a longitudinal sealing adhesive layer (4); S6. Third application of adhesive: Apply a third environmentally friendly water-based heat sealant to the surface of the protective layer (13) to form a corner adhesive layer (5); S7. Preheating before lamination: Heat the heat-sealing adhesive layer (3) formed in step S4; S8. Composite: Press the paper composite layer (1) after preheating in step S7 with the aluminum foil composite layer (2) to form a packaging material.

2. The manufacturing process of the easily recyclable packaging material according to claim 1, characterized in that, The steps for forming the protective layer in step S2 are as follows: S201, First coating: First, apply the first environmentally friendly water-based waterproof coating to the surface of the printed layer (12); The first environmentally friendly water-based waterproof coating comprises the following components by weight percentage: Polyacrylate, 30-40%; Water, 61-65%; Wetting agent, 0.1-1%; Defoamer, 0.1-1%; S202, Second coating: Apply a second environmentally friendly water-based waterproof coating to the surface of the first environmentally friendly water-based waterproof coating; The second environmentally friendly water-based waterproof coating comprises component B and component A in a mixing ratio of 3:100, wherein component A comprises the following components by weight percentage: Waterborne polyolefins, or 25-30%; Water, 70-75%; Wetting agent, 0.2-1%; Defoamer, 0.2-1%; Ammonia solution, 0.1-0.5%; Component B is a curing agent, which is polycarbodiimide.

3. The manufacturing process of the easily recyclable packaging material according to claim 1, characterized in that, The first environmentally friendly water-based heat sealant in step S4 comprises the following components by weight percentage: Waterborne polyolefin, 40-45%; Water, 50-60%; Wetting agent, 0.1-1%; Defoamer, 0.1-1%.

4. The manufacturing process of the easily recyclable packaging material according to claim 3, characterized in that, The second environmentally friendly water-based heat sealant in step S5 and the third environmentally friendly water-based heat sealant in step S6 have the same composition as the first environmentally friendly water-based heat sealant.

5. The manufacturing process of the easily recyclable packaging material according to claim 3, characterized in that, The second environmentally friendly water-based heat sealant and the third environmentally friendly water-based heat sealant mentioned in step S5 have the same composition, specifically including the following components by weight percentage: Polyacrylate, 35-40%; Water, 60-65%; Wetting agent, 0.1-1%; Defoamer, 0.1-1%.

6. The manufacturing process of the easily recyclable packaging material according to claim 3, characterized in that, The second environmentally friendly water-based heat sealant and the third environmentally friendly water-based heat sealant mentioned in step S5 have the same composition, specifically including the following components by weight percentage: Waterborne polyolefin, 25-30%; Water, 65-75%; Wetting agent, 0.1-1%; Defoamer, 0.1-1%; Ammonia solution, 0.1-1%.

7. The manufacturing process of the easily recyclable packaging material according to any one of claims 2-6, characterized in that, The wetting agent is alkylphenol polyethylene glycol phosphate, and the defoamer is water-soluble acrylic resin.

8. The manufacturing process of the easily recyclable packaging material according to any one of claims 1-6, characterized in that, The local coating method described in step S4 is as follows: An outer peripheral coating layer (31) is formed by coating the periphery of the second end face of the cardboard layer (11) with a first environmentally friendly water-based heat sealant; An intermediate coating layer (32) is formed by applying a first environmentally friendly water-based heat sealant to the middle area of ​​the second end face of the cardboard layer (11); The intermediate coating layer (32) is distributed in a multi-point or grid pattern.

9. The manufacturing process of the easily recyclable packaging material according to any one of claims 1-6, characterized in that, The aluminum foil composite layer (2) includes a second plastic layer (23), an EAA layer (24), an aluminum foil layer (22), and a first plastic layer (21) arranged sequentially from the inside to the outside.

10. A system for preparing easily recyclable packaging materials, characterized in that, The manufacturing process for the easily recyclable packaging material according to any one of claims 1-9 includes a printing device (100), a first coating device (200), a die-cutting device (300), a second coating device (400), a third coating device (500), a fourth coating device (600), a heating device (800), a pressing device (700), and an aluminum foil composite device (900) for forming an aluminum foil composite layer (2) arranged sequentially along the film material conveying direction. The printing apparatus (100) is used to form a printing layer (12) on the first end face of the cardboard layer (11); The first coating apparatus (200) is used to form a protective layer (13) on the printed layer (12); The die-cutting device (300) is used to form one or more of creases, lines or holes on the paper composite layer (1); The second coating device (400) is used to form a heat-sealing adhesive layer (3) on the second end face of the cardboard layer (11); The second coating device (500) is used to form a longitudinal sealing adhesive layer (4) on the surface of the paper composite layer (1); The third coating device (600) is used to form a corner adhesive layer (5) on the surface of the paper composite layer (1); The heating device (800) is used to heat the heat-sealing adhesive layer (3) on the back of the paper composite layer (1); The pressing device (700) is used to introduce and press the paper composite layer (1) conveyed from the heating device (800) and the aluminum foil composite layer (2) conveyed from the aluminum foil composite device (900) to form packaging material.

Images