Direct plating process of paper

Abstract

The invention belongs to the technical field of packaging paper production, and particularly relates to a direct plating process of paper. The method comprises the following steps: 1, flattening raw paper to ensure that the surface of the raw paper is flat; 2, base paper is coated with primer, and the paper coated with the primer is dried; 3, the base paper coated with the primer is fed into a vacuum evaporator to be subjected to primary aluminum plating; 4, cleaning the paperboard subjected to primary film coating, and removing impurities and residues on the surface of the paperboard; 5, secondary aluminizing is carried out, and an aluminized layer with the needed thickness is formed on the paper; 6, back coating is conducted on the aluminum-plated paper, coating used for back coating is a polyvinyl alcohol solution with the solid content of 5%, and the paper obtained after back coating is dried; the production range of a direct plating method is expanded, the method can be suitable for paper with higher gram weight, and meanwhile, the total thickness of an aluminum layer can be effectively increased through two times of aluminum plating, so that the fastness and durability of the aluminum layer are improved.

Description

Technical Field

[0001] This invention belongs to the field of packaging paper production technology, and in particular relates to a direct plating process for paper. Background Technology

[0002] Metallized paper technology, as an advanced surface treatment process, is widely used in the packaging field. Vacuum-metallized paper is widely used in food packaging due to its excellent moisture-proof, oil-proof, heat-resistant, and chemical corrosion-resistant properties. In the tobacco industry, metallized paper is used for cigarette inner linings and outer packaging, which can effectively enhance the product's aesthetics and anti-counterfeiting features. In alcoholic beverage packaging, the application of metallized paper can also increase the product's premium feel and market competitiveness. The use of metallized paper in pharmaceutical packaging can solve the problem of powder not easily being poured out due to electrostatic attraction in composite packaging films, while also improving the sealing and protection of the packaging.

[0003] Paper metallization processes mainly include two methods: direct metallization and transfer metallization. The transfer metallization method uses films such as PET (polyester film) or BOPP (polypropylene film) as the transfer substrate. Through processes like coating, metallization, lamination, and peeling, a metallic aluminum molecular layer is transferred to the surface of paper or paperboard via adhesive. This method suffers from a long process, complex control, and low yield. Furthermore, the disposal of used PET film after multiple transfers is also a problem. Direct metallization involves directly surface-treating the base paper and then completing the metallization process in a vacuum metallizing machine. This method does not require any adhesives or other intermediate media; instead, the metal layer is transferred through physical evaporation. It has fewer production steps, saves time, and allows for easier control of the metallized layer, resulting in higher metallization efficiency. Directly metallized paper also has better brightness and adhesion. However, the direct metallization method is limited by the paper's basis weight; currently, the basis weight of paper using the direct metallization method is often no more than 200 g / m². 2 . Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned technical problems by providing a direct plating process for paper, which expands the production range of the direct plating method and can be applied to paper with higher basis weight. At the same time, by plating aluminum twice, the total thickness of the aluminum layer can be effectively increased, thereby improving the strength and durability of the aluminum layer.

[0005] In view of this, the present invention provides a direct plating process for paper, comprising: Step 1: flattening the base paper to ensure a smooth surface; Step 2: applying a primer to the base paper and drying the coated paper; Step 3: feeding the primer-coated base paper into a vacuum evaporation machine for a first aluminum plating; Step 4: cleaning the coated paper to remove surface impurities and residues; Step 5: performing a second aluminum plating to form an aluminum layer of the required thickness on the paper; Step 6: applying a back coating to the aluminum-coated paper, using a 5% solids content polyvinyl alcohol solution as the coating, and drying the back-coated paper.

[0006] This technical solution improves aluminum layer thickness and strength: Two-stage aluminum plating effectively increases the total thickness of the aluminum layer, thereby enhancing its strength and durability. This is particularly important for applications requiring high abrasion resistance and barrier properties. It also improves surface smoothness: post-alumination treatments, such as cleaning and impurity removal, contribute to the quality of the second aluminum plating, resulting in a more uniform and smooth final aluminum layer. Furthermore, it enhances barrier properties: staged aluminum plating significantly improves the material's barrier properties against gases, water vapor, and light, extending the shelf life of the contents. This is especially important for products requiring long-term preservation, such as food and pharmaceuticals. It also improves appearance: staged aluminum plating makes the cardboard surface brighter and more aesthetically pleasing, enhancing the product's grade and market competitiveness. This is particularly important in the packaging industry, as appearance is often a key factor for consumers when choosing a product. Finally, it reduces production costs: although staged aluminum plating increases the number of process steps, the thinner plating layers each time reduce the amount of aluminum used, thus lowering production costs to some extent. Finally, it increases production efficiency: staged aluminum plating can improve production efficiency by optimizing process parameters without sacrificing product quality. This is particularly advantageous for large-scale production. High adaptability: The step-by-step metallization process can be adjusted according to different substrates and product requirements, exhibiting strong adaptability. This makes the process widely applicable in the production of various composite packaging materials. In summary, step-by-step metallization not only improves product quality and performance but also reduces costs and increases production efficiency to some extent.

[0007] In the above technical solution, further, in step three, when the paper needs to form a specific pattern or distribution for aluminum plating, a mask can be applied to the cardboard to prevent aluminum vapor from depositing in areas where aluminum plating is not required.

[0008] In the above technical solution, further, the material is removed or replaced before the secondary aluminum plating in step five so that an aluminum plating layer can be formed in the new area during the secondary aluminum plating.

[0009] In the above technical solution, further, in step three, the vacuum evaporation machine is set with a vacuum degree of not less than 0.4 Pa and a temperature of 1200℃~1400℃. The aluminum material evaporates into gaseous aluminum inside, and the running speed of the cardboard is 0.75-2.25 m / s. The gaseous aluminum adheres to the surface of the paper to form an aluminum-plated layer.

[0010] In the above technical solution, furthermore, the drying in steps two and six is ​​a multi-stage drying process, with the drying device temperatures being 95℃, 100℃, and 95℃ respectively. In the above technical solution, further, the primer used in step two can be an electron beam curable coating or a water-based acrylic modified polyurethane coating. After the primer is dried and cured, a paper with a smooth surface is obtained.

[0011] In the above technical solution, further, in step five, the moisture content of the paper is controlled to be 4.5-5.5% during the drying process.

[0012] In the above technical solution, further, in step two, the moisture content of the paper is controlled to be 3.5-6% during the drying process.

[0013] Furthermore, the above technical solution also includes the patterning or smoothing treatment of the aluminum coating layer on the paper before back coating in step six.

[0014] The beneficial effects of this invention are: 1. The above direct plating process is applicable to a weight of 200-300 g / m². 2 This method is more suitable for paper with a surface area of ​​200 g / m² than the original direct coating method. 2 The following paper represents a significant advancement, directly reflected in the expanded production range of direct metallization. It eliminates the need for any adhesives or other intermediate media, achieving metal layer transfer through a physical evaporation process. This reduces production steps, saves time, and allows for direct metallization, making the metallized layer easier to control and increasing efficiency. Furthermore, direct-metallized paper boasts better brightness and adhesion. Using higher grammage paper allows it to withstand greater mechanical strength and temperature during production, resulting in a more robust and durable final product that better protects the contents from environmental influences. The smoother and brighter surface of high-grammage metallized paper enhances the product's appearance, making packaging more attractive to consumers. This high-quality appearance is crucial for enhancing brand image and market competitiveness. 2. By applying aluminum twice, the total thickness of the aluminum layer can be effectively increased, thereby improving the strength and durability of the aluminum layer. This is especially important for applications requiring high wear resistance and barrier properties. 3. Post-alumination treatments, such as cleaning and impurity removal, help improve the quality of the second aluminization, resulting in a more uniform and smooth final aluminum layer. Detailed Implementation

[0015] The technical solutions in the embodiments of this application are clearly described below. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0016] In the description of this application, it should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0017] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those described, and the objects distinguished by "first," "second," etc., are generally of the same class, without limiting the number of objects; for example, the first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0018] It should be noted that in the description of this application, the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0019] It should be noted that, in this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0020] First embodiment: This embodiment provides a direct plating process for paper, including: Step 1: flattening the base paper to control its flatness; Step 2: applying a primer to the base paper and drying the coated paper; Step 3: feeding the primer-coated base paper into a vacuum evaporation machine for a first aluminum plating; Step 4: cleaning the coated paper to remove surface impurities and residues; Step 5: performing a second aluminum plating to form an aluminum layer of the required thickness on the paper; Step 6: applying a back coating to the aluminum-coated paper using a 5% solids content polyvinyl alcohol solution, and drying the back-coated paper.

[0021] Increased Aluminum Layer Thickness and Strength: Two-stage aluminum plating effectively increases the total thickness of the aluminum layer, thereby improving its strength and durability. This is especially important for applications requiring high abrasion resistance and barrier properties. Improved Surface Smoothness: Post-aluminating treatments, such as cleaning and impurity removal, help improve the quality of the second aluminum plating, resulting in a more uniform and smooth final aluminum layer. Enhanced Barrier Properties: Step-by-step aluminum plating significantly improves the material's barrier properties against gases, water vapor, and light, extending the shelf life of the contents. This is particularly important for products requiring long-term preservation, such as food and pharmaceuticals. Improved Appearance: Step-by-step aluminum plating makes the cardboard surface brighter and more aesthetically pleasing, enhancing the product's grade and market competitiveness. This is especially important in the packaging industry, as appearance is often a key factor for consumers when choosing a product. Reduced Production Costs: Although step-by-step aluminum plating increases the number of process steps, the thinner each plating layer reduces the amount of aluminum used, thus lowering production costs to some extent. Increased Production Efficiency: Step-by-step aluminum plating can improve production efficiency by optimizing process parameters without sacrificing product quality. This is particularly advantageous for large-scale production. High adaptability: The step-by-step metallization process can be adjusted according to different substrates and product requirements, exhibiting strong adaptability. This makes the process widely applicable in the production of various composite packaging materials. In summary, step-by-step metallization not only improves product quality and performance but also reduces costs and increases production efficiency to some extent.

[0022] In step three, when the paper needs to be aluminum coated to form a specific pattern or distribution, a mask can be applied to the cardboard to prevent aluminum vapor from depositing in areas where aluminum coating is not required.

[0023] In step five, the material is removed or replaced before the second aluminum plating so that an aluminum plating layer can be formed in the new area during the second aluminum plating.

[0024] In step three, the vacuum evaporation machine is set to a vacuum level of no less than 0.4 Pa and a temperature of 1200℃~1400℃. The aluminum material evaporates into gaseous aluminum inside the machine. The running speed of the cardboard is 0.75-2.25 m / s. The gaseous aluminum adheres to the surface of the paper to form an aluminum coating layer.

[0025] Both steps two and six involve multi-stage drying, with the drying equipment temperatures set at 95℃, 100℃, and 95℃ respectively. In step two, the primer can be either an electron beam cured coating or a water-based acrylic-modified polyurethane coating. After the primer dries and cures, a smooth paper surface is obtained. The primer layer can significantly improve the adhesion between the aluminum layer and the paper, reducing the possibility of aluminum layer peeling off, thereby improving the product's durability and service life. The use of the primer layer can also make the final aluminum-plated product surface brighter and smoother, improving the product's appearance quality and market competitiveness. Using water-based acrylic-modified polyurethane coating as the primer is more environmentally friendly than traditional solvent-based coatings, reducing the impact on the environment and human health.

[0026] In step five, the paper moisture content is controlled to be 4.5-5.5% during the drying process.

[0027] In step two, the paper moisture content is controlled to be 3.5-6% during the drying process.

[0028] It also includes the patterning or smoothing treatment of the aluminum-coated paper layer before back coating in step six. The aluminum film is pressed on the paper by an aluminum foil imprinting machine to create patterns or smooth the surface of the aluminum film, thus meeting production requirements.

[0029] The above-mentioned direct plating process is applicable to a weight of 200-300 g / m². 2 This method is more suitable for 200g / m² paper than the original direct coating method. 2 The following paper represents a significant advancement, directly reflected in the expanded production range of direct metallization. It eliminates the need for any adhesives or other intermediate media, achieving metal layer transfer through a physical evaporation process. This reduces production steps, saves time, and allows for direct metallization, making the metallized layer easier to control and increasing efficiency. Furthermore, direct-metallized paper boasts better brightness and adhesion. Using higher grammage paper allows it to withstand greater mechanical strength and temperature during production, resulting in a more robust and durable final product that better protects the contents from environmental influences. The smoother and brighter surface of high-grammage metallized paper enhances the product's appearance, making packaging more attractive to consumers. This high-quality appearance is crucial for enhancing brand image and market competitiveness.

[0030] Unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application is not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A direct plating process for paper, characterized in that, include: Step 1: Flatten the paper to ensure a smooth surface; Step 2: Apply a primer to the base paper and dry the paper after the primer has been applied. Step 3: The base paper with the primer applied is fed into a vacuum evaporation machine for a first aluminum plating. Step 4: Clean the card after the first coating to remove impurities and residues from the surface; Step 5: Perform a second aluminum plating to form an aluminum plating layer of the required thickness on the paper; Step 6: Apply a back coating to the aluminum-coated paper. The coating used for the back coating is a 5% solids content polyvinyl alcohol solution. Then, dry the paper after back coating.

2. The direct plating process for paper according to claim 1, characterized in that, In step three, when the paper needs to be aluminum-coated to form a specific pattern or distribution, a mask can be applied to the cardboard to prevent aluminum vapor from depositing in areas where aluminum coating is not required.

3. The direct plating process for paper according to claim 2, characterized in that, In step five, the material is removed or replaced before the secondary aluminum plating so that an aluminum plating layer can be formed in the new area during the secondary aluminum plating.

4. The direct plating process for paper according to claim 1, characterized in that, In step three, the vacuum evaporation machine is set to a vacuum degree of not less than 0.4 Pa and a temperature of 1200℃~1400℃. The aluminum material evaporates into gaseous aluminum inside the machine. The running speed of the cardboard is 0.75-2.25 m / s. The gaseous aluminum adheres to the surface of the paper to form an aluminum-plated layer.

5. The direct plating process for paper according to claim 1, characterized in that, The drying in steps two and six is ​​a multi-stage drying process, with the drying device temperatures being 95℃, 100℃, and 95℃, respectively.

6. The direct plating process for paper according to claim 1, characterized in that, In step two, the primer can be an electron beam cured coating or a water-based acrylic modified polyurethane coating. After the primer is dried and cured, a paper with a smooth surface is obtained.

7. The direct plating process for paper according to claim 1, characterized in that, In step five, the drying process controls the paper moisture content to be 4.5% to 5.5%.

8. The direct plating process for paper according to claim 1, characterized in that, In step two, the drying process controls the paper moisture content to be between 3.5% and 6%.

9. A direct plating process for paper according to any one of claims 1-9, characterized in that, It also includes the patterning or smoothing treatment of the aluminum coating layer on the paper before back coating in step six.