Aqueous coating for paper modification and method of preparation, coating, modified tipping paper

Abstract

The present application belongs to the technical field of functional polymer film, and particularly relates to a water-based paint for paper modification, a preparation method thereof, a coating, and modified tipping paper. In terms of the total mass of the water-based paint being 100%, the water-based paint comprises the following mass percentage of raw material components: 5-20% of a film-forming agent, 0.2-5% of a cross-linking agent, and 0.7-12% of an additive, and the rest is water; the film-forming agent is at least one selected from modified polyurethane, acrylic-polyurethane hybrid resin, and bio-based polyurethane. The water-based paint is applied on the surface of the tipping paper to form a coating on the surface of the paper, and the surface energy of the paper is actively controlled to be accurately matched with the surface tension of the printing ink, so that the technical problems of poor ink wettability and difficult leveling of high-air-permeability self-permeable tipping paper caused by low surface energy and micro-pore structure are fundamentally solved, the defect rate of printing white spots / missing printing is greatly reduced, the line breakage and virtual phenomenon are reduced, and the air permeability of the paper and the ink adhesion are improved.

Description

Technical Field

[0001] This invention belongs to the field of functional polymer film technology, specifically relating to a water-based coating for paper modification, and more particularly to a method for preparing the water-based coating for paper modification, a coating, and a modified tipping paper. Background Technology

[0002] Tipping paper, as an important component of cigarette products, directly affects the product's appearance and brand image through its printing quality. Tipping paper, especially high-permeability self-permeable tipping paper, typically has a low surface energy or a unique microporous structure. This surface characteristic leads to poor wetting and leveling difficulties for conventional gravure printing inks during the printing process, easily resulting in quality defects such as white spots, broken lines, and blurring, which seriously affect the product's appearance and batch consistency.

[0003] Currently, the main method used in the industry to solve this problem is to adjust the ink formulation by adding additives such as wetting agents and leveling agents to improve the ink's adaptability to the paper surface. However, this method has significant limitations: the amount of additives can be limited, and excessive addition will affect the ink's drying speed, adhesion, and storage stability; the same ink formulation is difficult to adapt to different brands and batches of tipping paper, resulting in poor universality; these methods cannot fundamentally solve the problem of mismatch between the paper surface and the printing process, leading to recurring printing quality issues. Summary of the Invention

[0004] The technical problem to be solved by this application is to provide a water-based coating for paper modification and its preparation method and coating, which improves the printability of tipping paper surface, effectively solves various defects existing in the prior art, and ensures good process adaptability and product consistency, providing a reliable guarantee for high-quality printing of high-permeability self-permeable tipping paper.

[0005] Firstly, this application provides a water-based coating for paper modification, comprising, by weight percentage, the following raw material components based on 100% of the total mass of the water-based coating: Film-forming agent 5%~20% Crosslinking agent 0.2%~5% Additives: 0.7%~12% The rest is water; The film-forming agent is selected from at least one of modified polyurethane, acrylic-polyurethane hybrid resin, and bio-based polyurethane.

[0006] In some possible implementations, the crosslinking agent is selected from at least one of polycarbodiimide, methyl vinyl MQ silicone resin, photocurable crosslinking agent, and enzyme-catalyzed crosslinking agent.

[0007] In some possible implementations, the additives include leveling agents, antistatic agents, hydrophobic agents, antibacterial agents, and pH adjusters.

[0008] In some possible implementations, the leveling agent is selected from at least one of polysiloxane-polyether copolymers and acrylic leveling agents.

[0009] In some possible implementations, the antistatic agent is selected from alkyl imidazolines.

[0010] In some possible implementations, the hydrophobic agent is selected from organofluorine modified polyacrylates.

[0011] In some possible implementations, the antimicrobial agent is selected from at least one of Clariant JMAC LP10, Foshan Lanfeng Additives Co., Ltd. BIT-10, and Foshan Lanfeng Additives Co., Ltd. TIO-302.

[0012] In some possible implementations, the pH adjuster is selected from organic amines.

[0013] In some possible implementations, the leveling agent in the water-based coating has a mass percentage content of 0.5% to 3%.

[0014] In some possible implementations, the antistatic agent in the water-based coating has a mass percentage content of 0.1% to 1%.

[0015] In some possible implementations, the hydrophobic agent in the water-based coating has a mass percentage content of 0.1% to 1%.

[0016] In some possible implementations, the antibacterial agent in the water-based coating has a mass percentage content of 0.05% to 1%.

[0017] In some possible implementations, the pH adjuster adjusts the pH of the water-based coating to 7.0-8.5.

[0018] In some possible implementations, the film-forming agent in the water-based coating has a mass percentage content of 8% to 15%.

[0019] In some possible implementations, the crosslinking agent in the water-based coating has a mass percentage content of 0.5% to 3%.

[0020] Secondly, this application provides a method for preparing a water-based coating for paper modification, comprising the following steps: 5-20 parts by weight of film-forming agent, 0.5-3 parts by weight of crosslinking agent, 0.7-12 parts by weight of additives, and 75-95 parts by weight of water are mixed to obtain a water-based coating for paper modification. The film-forming agent is selected from at least one of modified polyurethane, acrylic-polyurethane hybrid resin, and bio-based polyurethane.

[0021] In some possible implementations, the hybrid processing includes the following steps: The film-forming agent is added to a first portion of water for a first mixing process to obtain a first premixed solution. The additive is mixed with a second portion of water to obtain a second premixed solution. The first premixed solution and the second premixed solution are subjected to a third mixing treatment, and the pH value is adjusted to 7.0~8.5 to obtain a mixture; Eight hours before use, a crosslinking agent is added to the mixture for a fourth mixing treatment to obtain the water-based coating.

[0022] Thirdly, this application provides a coating obtained by using the water-based coatings described above and / or water-based coatings prepared by the methods described above.

[0023] Fourthly, this application provides a modified tipping paper, the modified tipping paper comprising a tipping paper body and a coating as described above laminated with the tipping paper body, the preparation method of the modified tipping paper comprising the following steps: The water-based coating is applied to the surface of the tipping paper using online micro-grooved roller coating technology, with a wet weight of 1 g / m². 2 ~3g / m 2 ; Dry at 60~80℃ or cure with ultraviolet light for 5~10 seconds.

[0024] The water-based coating for paper modification provided in the first aspect of this application constructs an ultra-thin functional transition layer on the surface of the paper by pre-coating the surface of the tipping paper with a water-based coating of a specific formula. This actively regulates the surface energy of the paper, making it precisely match the surface tension of the printing ink. This fundamentally solves the technical problems of poor ink wetting and difficulty in leveling caused by the low surface energy and microporous structure of high-permeability self-permeable tipping paper. It achieves excellent printing effects with a significant reduction in the rate of white spots / missed prints, a near elimination of broken or blurred fine lines, and a significant improvement in the stability of solid density. At the same time, it strictly maintains the core functional characteristic of paper permeability change ≤10%, and the ink adhesion fastness of achieving grade 0 through the cross-cut adhesion test verifies the bridging role of the coating. It completely overcomes the limitations of traditional ink end adjustment methods and provides a systematic and universal technical guarantee for the printing quality of tipping paper.

[0025] The second aspect of this application provides a method for preparing water-based coatings for paper modification. By mixing a film-forming agent with a crosslinking agent, additives, and water in a specific ratio, a dense and flexible continuous protective film is formed on the paper surface, effectively improving the surface smoothness and ink absorption performance of the paper. A moderate crosslinking reaction occurs between the crosslinking agent and the film-forming agent molecular chains, constructing a three-dimensional network structure that significantly enhances the coating's water resistance, solvent resistance, and mechanical strength, preventing swelling and peeling during printing. The additive system optimizes the coating's dispersion stability, leveling, and wetting properties, ensuring uniform and defect-free coating distribution. The water-based system not only meets environmental protection requirements but also, through precise control of the component ratios, maintains a very low original air permeability of the paper while achieving a stable ink adhesion grade of 0, significantly reducing the white spot defect rate during printing. Simultaneously, it imparts excellent antibacterial properties and storage stability to the coating, providing a reliable technical guarantee for the high-quality production of high-permeability self-penetrating tipped paper in high-speed printing and complex usage environments.

[0026] The coating provided in the third aspect of this application has excellent ink adhesion, flexibility, and low or even zero volatile organic compound emissions. When applied to the surface of the tipping paper, the ink adhesion consistently reaches level 0, which significantly reduces the white spot defect rate in printing.

[0027] The modified tipping paper provided in the fourth aspect of this application has excellent ink adhesion, low or even zero volatile organic compound emissions, and a low rate of white spot defects in printing. Detailed Implementation

[0028] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0029] The first aspect of this application provides a water-based coating for paper modification, comprising, by weight percentage, the following raw material components based on 100% of the total mass of the water-based coating: Film-forming agent 5%~20% Crosslinking agent 0.2%~5% Additives: 0.7%~12% The rest is water; The film-forming agent is selected from at least one of modified polyurethane, acrylic-polyurethane hybrid resin, and bio-based polyurethane.

[0030] The water-based coating for paper modification provided in the first aspect of this application constructs an ultra-thin functional transition layer on the surface of the paper by pre-coating a water-based coating with a specific formula on the paper surface. This actively regulates the surface energy of the paper, making it precisely match the surface tension of the printing ink. This fundamentally solves the technical problems of poor ink wetting and difficulty in leveling caused by the low surface energy and microporous structure of high-permeability self-permeable tipping paper. It achieves excellent printing effects, such as a reduction of more than 90% in the rate of white spots / missed prints, the near elimination of broken or blurred fine lines, and a significant improvement in the stability of solid density. At the same time, it strictly maintains the core functional characteristic of paper permeability change ≤10%, and the ink adhesion fastness of achieving grade 0 through the cross-cut adhesion test verifies the bridging role of the coating. It completely overcomes the limitations of traditional ink end adjustment methods and provides a systematic and universal technical guarantee for the printing quality of tipping paper.

[0031] In some possible implementations, the crosslinking agent is selected from at least one of polycarbodiimide, methyl vinyl MQ silicone resin, photocurable crosslinking agent, and enzyme-catalyzed crosslinking agent. These crosslinking agents, as crosslinking systems, significantly enhance the stability of the three-dimensional network structure and the interfacial bonding strength of the functional transition layer; the polycarbodiimide crosslinking agent imparts excellent hydrolysis resistance and chemical stability to the coating, ensuring that the coating structure is not damaged by ink solvents during printing; the photocurable crosslinking agent enables rapid in-situ crosslinking, greatly improving production efficiency and forming a dense crosslinked network, further optimizing the precision of surface energy regulation; and the enzyme-catalyzed crosslinking agent achieves precise crosslinking under mild conditions, avoiding damage to paper fibers from high temperatures.

[0032] In some possible implementations, additives include leveling agents, antistatic agents, hydrophobic agents, antibacterial agents, and pH adjusters. Among these additives, leveling agents significantly improve the uniformity of coating spread on the tipping paper surface, ensuring consistent thickness of the functional transition layer and providing an ideal base for ink wetting; antistatic agents effectively eliminate electrostatic adsorption during the printing process, preventing paper dust and ink splatter, and further reducing the white spot defect rate; hydrophobic agents impart appropriate hydrophobic properties to the coating while maintaining low changes in air permeability, improving the water resistance and storage stability of printed products; antibacterial agents provide hygienic and safe protection for tipping paper, meeting the special requirements of cigarette products; pH adjusters ensure the chemical stability of the coating system, extend shelf life, and ensure workability; these additives work synergistically with film-forming agents and crosslinking agents to improve the overall performance and process adaptability of tipping paper printed products.

[0033] In some possible implementations, the leveling agent is selected from at least one of polysiloxane-polyether copolymers and acrylic leveling agents. Polysiloxane-polyether copolymers, with their excellent surface activity and interfacial migration capabilities, significantly reduce the surface tension of the coating system, enabling rapid and uniform spreading on the low surface energy surface of high-permeability self-permeable tipping paper. This effectively eliminates defects such as pinholes and orange peel during the coating process, ensuring uniform thickness of the functional transition layer. Acrylic leveling agents, on the other hand, exhibit excellent compatibility with film-forming agents such as acrylic-polyurethane hybrid resins in the system, further optimizing the leveling performance of the coating film and improving surface smoothness. Specifically, the polysiloxane-polyether copolymer is selected from at least one of BYK-306, BYK-307, BYK-333, SL-3302M, SL-3306, SL-3357, and SL-3415.

[0034] In some possible implementations, the antistatic agent is selected from alkyl imidazoline. In this embodiment, by introducing alkyl imidazoline as an antistatic agent into the water-based coating, the excellent polarity and adsorption capacity of the imidazoline ring structure in the alkyl imidazoline molecule are utilized, enabling it to firmly anchor onto the surface of the tipping paper fibers. Its long-chain alkyl groups extend outward to form a conductive network, effectively dissipating the accumulation of static charge generated during high-speed printing. This antistatic agent, in synergy with other additives such as polysiloxane-polyether copolymer leveling agents, not only significantly reduces the surface resistivity of the paper, preventing paper dust, ink splatter, and impurity adhesion caused by electrostatic adsorption, but also fundamentally reduces the generation of printing white spots and omissions. Simultaneously, its mild chemical properties ensure good compatibility with the modified polyurethane film-forming agent, without compromising the integrity of the functional transition layer. The alkyl imidazoline is selected from at least one of Tuyile® C-17 and Viktor® Amine TOH.

[0035] In some possible implementations, the hydrophobic agent is selected from organofluorine modified polyacrylate. In this embodiment, by utilizing the extremely low surface energy of the fluorocarbon segments in the organofluorine modified polyacrylate molecule, a dense hydrophobic barrier can be formed by directional alignment on the surface of the functional transition layer, significantly improving the hydrophobic performance of the coating (contact angle can reach over 110°), effectively blocking the penetration and erosion of environmental moisture and solvents in the ink; at the same time, its acrylate backbone has excellent compatibility and chemical bonding ability with film-forming agents such as acrylic-polyurethane hybrid resin in the system, ensuring that the hydrophobic function is firmly bonded to the coating substrate and will not fall off due to printing friction or long-term storage.

[0036] In some possible implementations, the antibacterial agent is selected from at least one of Clariant JMAC LP10, Foshan Lanfeng Additives Co., Ltd. BIT-10, and Foshan Lanfeng Additives Co., Ltd. TIO-302. These antibacterial agents not only construct an active defense barrier on the paper surface, effectively inhibiting the growth of bacteria, mold, and other microorganisms, and giving tipping paper excellent anti-mildew and anti-odor functions, but also have low addition amounts, good stability, and good compatibility with coating systems, without affecting the coating's transparency, flexibility, and ink adhesion, which are core printing properties. Clariant JMAC LP10 is an inorganic antibacterial agent with silver chloride deposited on a titanium dioxide carrier. Its working principle is to continuously and controllably release silver ions, which can penetrate the cell wall of microorganisms, bind to intracellular proteins and enzymes containing sulfhydryl groups to inactivate them, and interfere with DNA replication, thereby achieving a broad-spectrum and long-lasting bactericidal and bacteriostatic effect, and is not prone to drug resistance. The active ingredient of BIT-10 is usually 1,2-benzisothiazolin-3-one, which is a highly efficient organic heterocyclic bactericide. It mainly achieves the purpose of rapidly killing bacteria, fungi and yeast by destroying the cell membrane structure of microorganisms and inhibiting their respiratory metabolism and energy synthesis.

[0037] In some possible implementations, the pH adjuster is selected from organic amines. This embodiment utilizes the moderate alkalinity of the amino groups in organic amine molecules to precisely control the pH of the coating system to the optimal range of 7.0–8.5. This ensures the full dissolution and stability of film-forming agents such as acrylic-polyurethane hybrid resins while avoiding resin hydrolysis or cross-linking side reactions that may occur under strongly alkaline conditions. Simultaneously, the volatility of organic amines allows them to gradually escape during the coating drying process, preventing the residue of alkaline substances in the final coating and thus avoiding adverse effects on ink adhesion.

[0038] In some possible implementations, the leveling agent in water-based coatings contains 0.5% to 3% by mass. For example, the leveling agent content in water-based coatings can be any typical but non-limiting value, such as 0.5%, 1%, 1.5%, 2%, 2.5%, or 3%, or any value between any two points. In this case, the leveling agent can fully exert its function of reducing surface tension and promoting uniform coating spread, matching the molecular structure characteristics of polysiloxane-polyether copolymers or acrylic leveling agents to ensure uniform thickness and smooth surface of the functional transition layer. When the leveling agent content is below 0.5%, its surface tension regulating ability is insufficient, making it difficult to effectively eliminate defects such as pinholes and orange peel during the coating process, resulting in substandard surface smoothness of the functional transition layer and affecting the quality of subsequent ink printing. When the content exceeds 3%, excessive leveling agent will accumulate excessively on the coating surface, potentially causing the coating surface energy to be too low, which in turn reduces ink wettability and adhesion, while increasing production costs.

[0039] In some possible implementations, the antistatic agent in the waterborne coating has a mass percentage content of 0.1% to 1%. For example, the mass percentage content of the antistatic agent in the waterborne coating can be any typical but non-limiting value, such as 0.1%, 0.2%, 0.5%, 0.8%, or 1%, or any value between any two points. In this case, the alkyl imidazoline antistatic agent can fully utilize its cationic antistatic properties, forming a uniformly distributed conductive path on the surface of the functional transition layer, effectively reducing surface resistivity. When the antistatic agent content is below 0.1%, its distribution density on the coating surface is insufficient, making it difficult to form a continuous and effective conductive network, resulting in low static dissipation efficiency and failing to effectively solve the problem of electrostatic adsorption during the printing process. When the content exceeds 1%, excessive antistatic agent may form micro-phase separation in the coating, affecting the coating's transparency and mechanical strength, while also increasing unnecessary production costs.

[0040] In some possible implementations, the hydrophobic agent in the waterborne coating contains 0.1% to 1% by mass. For example, the mass percentage of the hydrophobic agent in the waterborne coating can be any typical but non-limiting value, such as 0.1%, 0.2%, 0.5%, 0.8%, or 1%, or any value between any two points. In this case, the hydrophobic agent can fully utilize its low surface energy characteristics, oriented to form a uniform and stable hydrophobic network on the surface of the functional transition layer, achieving an excellent contact angle of 110° to 120°. When the hydrophobic agent content is below 0.1%, the distribution density of the organofluorine modified polyacrylate on the coating surface is insufficient, making it difficult to form a continuous and dense hydrophobic barrier. This results in a low contact angle on the coating surface, failing to effectively block the penetration of environmental moisture and solvents in the ink, affecting printing quality and storage stability. When the content exceeds 1%, excessive hydrophobic agent will accumulate excessively on the coating surface, easily leading to excessively low surface energy, affecting ink wettability, and increasing the compatibility risk of fluorocarbon segments, potentially causing uneven microstructure in the coating.

[0041] In some possible implementations, the antibacterial agent in the waterborne coating has a mass percentage content of 0.05% to 1%. For example, the mass percentage content of the antibacterial agent in the waterborne coating can be any typical but non-limiting point value or any value between any two points, such as 0.05%, 0.1%, 0.2%, 0.5%, 0.8%, or 1%. In this case, its broad-spectrum antibacterial properties can be fully utilized, forming a uniformly distributed antibacterial network in the functional transition layer.

[0042] In some possible implementations, a pH adjuster adjusts the pH of the waterborne coating to 7.0-8.5. In this embodiment, a pH adjuster such as triethylamine or AMP-95 ensures that the surface of the emulsion particles carries an appropriate amount of negative charge, maintaining a stable dispersion system, while providing a suitable film-forming environment for the waterborne resin, thus achieving the optimal balance between the stability and application performance of the coating system.

[0043] In some possible implementations, the film-forming agent in the waterborne coating comprises 8% to 15% by mass. For example, the film-forming agent in the waterborne coating may be any typical but not limiting value, such as 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%, or any value between any two points. In this case, the coating forms a dense and uniform continuous phase structure, significantly improving the coating's adhesion, flexibility, and weather resistance.

[0044] In some possible implementations, the crosslinking agent in the waterborne coating has a mass percentage content of 0.5% to 3%. For example, the mass percentage content of the crosslinking agent in the waterborne coating can be any typical but non-limiting value, such as 0.5%, 1%, 1.5%, 2%, 2.5%, or 3%, or any value between any two points. In this case, it can undergo a moderate crosslinking reaction with the carboxyl, hydroxyl, and other functional groups of the film-forming agent to form a dense and elastic three-dimensional network structure, ensuring that the coating has a high crosslinking density and flexibility.

[0045] A second aspect of this application provides a method for preparing a water-based coating for paper modification, comprising the following steps: 5-20 parts by weight of film-forming agent, 0.5-3 parts by weight of crosslinking agent, 0.7-12 parts by weight of additives, and 75-95 parts by weight of water are mixed to obtain a water-based coating for paper modification. The film-forming agent is selected from at least one of modified polyurethane, acrylic-polyurethane hybrid resin, and bio-based polyurethane.

[0046] The second aspect of this application provides a method for preparing waterborne coatings for paper modification. By mixing high-performance film-forming agents such as modified polyurethane, acrylic-polyurethane hybrid resin, or bio-based polyurethane with crosslinking agents, additives, and water in a specific ratio, a dense and flexible continuous protective film is formed on the paper surface, effectively improving the surface smoothness and ink absorption performance of the paper. A moderate crosslinking reaction occurs between the crosslinking agent and the film-forming agent molecular chains, constructing a three-dimensional network structure, significantly improving the coating's water resistance, solvent resistance, and mechanical strength, preventing swelling and peeling during printing. The additive system optimizes the coating's dispersion stability, leveling, and wetting properties, ensuring uniform coating distribution and no defects. The waterborne system not only meets environmental protection requirements but also, through precise control of the component ratios, maintains the original air permeability of the paper while achieving a stable ink adhesion grade of 0, significantly reducing the white spot defect rate during printing. Simultaneously, it imparts excellent antibacterial properties and storage stability to the coating, providing a reliable technical guarantee for the high-quality production of high-permeability self-penetrating tipped paper in high-speed printing and complex usage environments.

[0047] In some possible implementations, the hybrid processing includes the following steps: The film-forming agent is added to the first portion of water for the first mixing treatment to obtain the first premixed solution; The additives are mixed with the second portion of water to obtain a second premixed solution. The first premixed solution and the second premixed solution are mixed in a third process, and the pH value is adjusted to 7.0~8.5 to obtain a mixture. Eight hours before use, a crosslinking agent is added to the mixture for a fourth mixing treatment to obtain a water-based coating.

[0048] In the above implementation method, the film-forming agent is first premixed with the first portion of water separately to ensure that the film-forming agent and other polymer materials are fully swollen and dispersed to form a uniform and stable first premixed liquid. At the same time, various additives are premixed with the second portion of water to allow the functional additives to fully exert their effects and form a second premixed liquid with coordinated performance. Subsequently, the two premixed liquids are combined and the pH value is precisely adjusted to 7.0~8.5, which not only optimizes the charge state and dispersion stability of the film-forming agent molecules, but also creates a suitable chemical environment for the subsequent crosslinking reaction. The crosslinking agent is added only within 8 hours before use, which effectively avoids the problem of coating gelation and shortened pot life caused by premature crosslinking reaction, ensuring the long-term stability of the coating during storage, and at the same time, it can exert the best crosslinking effect during construction to form a dense and elastic three-dimensional network structure.

[0049] A third aspect of this application provides a coating obtained by using the above-described water-based coating and / or a water-based coating prepared by the above-described method.

[0050] The coating provided in the third aspect of this application has excellent ink adhesion, flexibility, and low or even zero volatile organic compound emissions. When applied to the surface of the tipping paper, the ink adhesion consistently reaches level 0, which significantly reduces the white spot defect rate in printing.

[0051] Fourthly, this application provides a modified tipping paper, which includes a tipping paper body and the above-mentioned coating compounded with the tipping paper body. The preparation method of the modified tipping paper includes the following steps: Water-based coatings are applied to the surface of the tipping paper using online micro-grooving roller coating technology, with a wet weight of 1 g / m². 2 ~3g / m 2 ; Dry at 60~80℃ or cure with ultraviolet light for 5~10 seconds.

[0052] The modified tipping paper provided in the fourth aspect of this application has excellent ink adhesion, low or even zero volatile organic compound emissions, and a low rate of white spot defects in printing.

[0053] Specifically, an online micro-grooved roller coating technology is used to uniformly spray water-based coatings onto the surface of the tipping paper. This technology features high coating precision, good coating thickness consistency, and adaptability to high-speed production lines. The final coating maintains the original air permeability of the paper while achieving a stable ink adhesion grade of 0, significantly reducing the white spot defect rate and exhibiting excellent performance with over 100 solvent wiping cycles.

[0054] For example, when using online micro-grooved roller coating technology to spray water-based coatings, the wet weight of the coating can be 1 g / m³. 2 1.5g / m 2 2g / m 2 2.5g / m 2 3g / m 2 Typical but not restrictive point values ​​or values ​​between any two points. In this case, the amount of coating is minimized while ensuring the functionality of the coating, thus avoiding the decrease in paper air permeability caused by excessive coating thickness, and ensuring complete coating coverage and performance.

[0055] During the curing stage, the tipping paper coated with the water-based paint is then sent to a low-temperature drying or UV curing zone for curing. For example, the drying temperature can be any typical but non-limiting value, such as 60°C, 65°C, 70°C, 75°C, or 80°C, or any value between any two values; the curing time can be any typical but non-limiting value, such as 5 seconds, 6 seconds, 7 seconds, 8 seconds, 9 seconds, or 10 seconds, or any value between any two values; and the UV wavelength can be any typical but non-limiting value, such as 254nm or 395nm, or any value between any two values. In this configuration, not only is production efficiency significantly improved, meeting the demands of modern high-speed printing production lines, but the low-temperature curing conditions also effectively protect the fiber structure of the tipping paper, preventing paper deformation or performance degradation caused by high temperatures. Especially when UV curing is used, the synergistic effect with the specific photoinitiating system in the paint allows for cross-linking reactions to be completed in a very short time, forming a highly cross-linked, dense network structure, further enhancing the coating's water resistance, solvent resistance, and mechanical strength.

[0056] In some possible implementations, the coating thickness is 0.5 μm to 1.0 μm. For example, the coating thickness can be any typical but non-limiting point value or any value between any two points, such as 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, or 1.0 μm. In this case, it is beneficial to reduce paint consumption and production costs, while avoiding quality problems such as coating cracking and peeling common in traditional thick coating processes.

[0057] To ensure that the above-described implementation details and operations of this application can be clearly understood by those skilled in the art, and to demonstrate the significant improvement in the performance of the water-based coatings for paper modification and their preparation methods, the following examples illustrate the above technical solutions. Specifically: Example 1 A water-based coating for paper modification, the preparation of which includes the following steps: The following mixtures were prepared: film-forming agent: Covestro Bayhydrol® A 2470 10kg; crosslinking agent: polycarbodiimide 1.2kg; additives: leveling agent BYK-306 1.5kg, antistatic agent Tuyle® C-17 0.3kg; and water 87kg. Triethanolamine was then added to adjust the pH of the system to 7.5 to obtain a water-based coating for paper modification with a surface tension of 23mN / m.

[0058] A modified tipping paper, the preparation of which includes the following steps: The water-based coating is applied to the surface of the tipping paper using online micro-grooving roller coating technology, with a wet weight of 2 g / m². 2 ; The coating was obtained by drying in a hot air oven at 70°C for 8 seconds, with a thickness of 0.8 μm.

[0059] Example 2 A water-based coating for paper modification, the preparation of which includes the following steps: The following were mixed: film-forming agent: SL-7520 12kg from Hangzhou Chongyao Technology Development Co., Ltd.; crosslinking agent: DY-VMQ101 (0.9) 2kg; additives: leveling agent YB-8824 1.5kg, hydrophobic agent Xinno® WE-D887BR 0.3kg; and water 84.5kg to obtain a water-based coating for paper modification.

[0060] A modified tipping paper, prepared in the same way as in Example 1.

[0061] Example 3 A water-based coating for paper modification, the preparation of which includes the following steps: The following mixtures were prepared: 8 kg of film-forming agent (carboxymethyl chitosan (CMCS) and tea polyphenol (EGCG) complex); 0.5 kg of crosslinking agent (QL-050 from Jiangsu Boli Biological Products Co., Ltd.); 2 kg of leveling agent (BYK-306); and 89.5 kg of water; to obtain a water-based coating for paper modification. The mass ratio of carboxymethyl chitosan to tea polyphenol was 100:1.

[0062] A modified tipping paper, prepared in the same way as in Example 1.

[0063] Comparative Example 1 The splicing paper is not coated with the above coating.

[0064] The adhesion, abrasion resistance, air permeability, flexibility, and thickness of the prepared modified tipping paper were tested using the following methods: 1. Adhesion test (cross-cut test) Test objective: To evaluate the adhesion strength between the coating and the tipping paper surface, and the adhesion strength between the ink and the modified tipping paper.

[0065] Testing instruments: cross-cut tester (or utility knife), standard tape (such as CTZ-405), magnifying glass.

[0066] Test steps: Use a scribing tool to draw 11 parallel lines on the coating surface, spaced 1 mm apart, extending to the substrate; then draw 11 vertical lines to form 100 1 mm × 1 mm squares 2; Secure the tape tightly to the grid, ensuring there are no gaps, then quickly pull the tape up at a 45° angle. Observe the adhesion of the squares. If there is no adhesion, the adhesion is rated as 100 / 100 (level 0); if there is adhesion, the level is downgraded proportionally.

[0067] 2. Abrasion resistance test Test objective: To evaluate the coating's resistance to friction during packaging and cigarette machine conveying processes.

[0068] Testing instrument: Abrasion tester (such as Taber abrasion tester) Test procedure: Friction method: Use a friction wheel (such as a grinding wheel or felt wheel) with a certain weight to rotate on the coating surface a specified number of times, observe whether the coating is exposed or measure its mass loss rate.

[0069] 3. Air permeability test Test objective: To evaluate the air permeability of the modified tipping paper and ensure that the cigarette ventilation rate is not negatively affected.

[0070] Testing instrument: Paper air permeability meter Test steps: Cut a sample of the modified tipping paper to the specified size, clamp it on the test head of the instrument, and ensure a tight seal without any air leakage.

[0071] A certain pressure difference (usually 1.00 kPa or 0.75 kPa) is applied, and the volume of air passing through a certain area of ​​paper per unit time is measured (the unit is usually CU or cm). 3 / min·cm 2 ).

[0072] 4. Flexibility test (bending test) Test objective: To evaluate the coating's resistance to cracking and peeling when the paper is bent.

[0073] Testing instruments: tapered shaft bending tester or cylindrical shaft (1mm, 2mm, 3mm, etc. in diameter).

[0074] Test steps: The coated and dried tipping paper sample (coating facing out) was bent 90° or 180° around a cylindrical shaft of different diameters. After bending, use a 4x magnifying glass to observe whether there are cracks, patterns, or peeling of the coating at the bent part; The flexibility grade is determined by the smallest cylindrical shaft diameter that does not damage the coating (the smaller the diameter, the better the flexibility; generally, 1~3mm is required to be qualified).

[0075] 5. Thickness Test The thickness of the spliced ​​paper after coating was tested directly using a paper thickness gauge; Test objective: To evaluate coating thickness; Testing instrument: Micrometer thickness gauge, accuracy 0.001mm.

[0076] Test procedure: Randomly select one sample from the temperature and humidity equilibrated sample set. Randomly select five sheets from this sample set and fold them in half lengthwise to form 10 layers. Then, cut two stacks of 0.01m each in the transverse direction. 2 A total of 20 samples were prepared. The thickness of each sample was measured using a thickness gauge, with one measurement point for each sample, and the average value was taken.

[0077] The test results are shown in Table 1 below.

[0078] Table 1

[0079] As shown in Table 1, the coating and ink adhesion of Examples 1-3 all reached ISO 2409 standard level 0 (100 / 100 no peeling), while Comparative Example 1 (uncoated) only reached level 2. This indicates that the water-based coating described in this application can form a strong bond with the tipping paper substrate, effectively avoiding the problems of coating peeling and high white spot defect rate of ink on modified tipping paper during printing or subsequent processing.

[0080] Examples 1-3 all showed "no substrate exposure and no discoloration" in the GB / T 7706 abrasion resistance test, which was significantly better than the "slight discoloration" of Comparative Example 1. This indicates that the coating has good surface density and abrasion resistance, and can withstand the mechanical wear during cigarette packaging and high-speed machine conveying, thus improving product durability and appearance stability.

[0081] The air permeability of Examples 1-3 were 290 CU, 286 CU and 299 CU, respectively, which were only about 6.9% to 10.6% lower than that of Comparative Example 1 (320 CU). This is far below the industry-acceptable ≤15% change threshold, which fully verifies that the ultra-thin coating (about 0.8 μm) design of this application effectively retains the original high air permeability of the tipping paper while providing functionality, thus meeting the ventilation requirements of self-permeable cigarettes.

[0082] Examples 1-3 all completed bending without creases on a 1 mm diameter shaft in the GB / T 1731-2020 bending test, significantly better than Comparative Example 1 (only 3 mm was acceptable). This indicates that the coating has excellent ductility and elasticity, and can be repeatedly bent without creases during cigarette forming, folding and other processes, ensuring processing adaptability.

[0083] This application successfully prepared an ultra-thin functional coating with high adhesion, excellent abrasion resistance, good air permeability retention, and outstanding flexibility by optimizing the combination of film-forming agents, crosslinking agents, and functional additives, and by using precise coating and curing processes. Compared with untreated paper, its overall performance is significantly improved without affecting the core usability of tipping paper, fully demonstrating the advanced nature and practicality of this water-based coating system in the field of paper modification.

[0084] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this application as described above, which are not provided in detail for the sake of brevity.

[0085] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

Claims

1. A water-based coating for paper modification, characterized in that, Based on the total mass of the water-based coating as 100%, it includes the following raw material components by mass percentage: Film-forming agent 5%~20% Crosslinking agent 0.2%~5% Additives: 0.7%~12% The rest is water; The film-forming agent is selected from at least one of modified polyurethane, acrylic-polyurethane hybrid resin, and bio-based polyurethane.

2. The water-based coating for paper modification according to claim 1, characterized in that, The crosslinking agent is selected from at least one of polycarbodiimide, methyl vinyl MQ silicone resin, photocurable crosslinking agent, and enzyme-catalyzed crosslinking agent; And / or, the additives include leveling agents, antistatic agents, hydrophobic agents, antibacterial agents, and pH adjusters.

3. The water-based coating for paper modification according to claim 2, characterized in that, The leveling agent is selected from at least one of polysiloxane-polyether copolymer and acrylic leveling agent; And / or, the antistatic agent is selected from alkyl imidazolines; And / or, the hydrophobic agent is selected from organofluorine modified polyacrylates.

4. The water-based coating for paper modification according to claim 2 or 3, characterized in that, The antibacterial agent is selected from at least one of Clariant JMAC LP10, Foshan Lanfeng Additives Co., Ltd. BIT-10, and Foshan Lanfeng Additives Co., Ltd. TIO-302; And / or, the pH adjuster is selected from organic amines.

5. The water-based coating for paper modification according to claim 4, characterized in that, In the water-based coating, the leveling agent has a mass percentage content of 0.5% to 3%. And / or, in the water-based coating, the antistatic agent has a mass percentage content of 0.1% to 1%; And / or, in the water-based coating, the hydrophobic agent has a mass percentage content of 0.1% to 1%; And / or, in the water-based coating, the antibacterial agent has a mass percentage content of 0.05% to 1%; And / or, the pH adjuster adjusts the pH value of the water-based coating to 7.0~8.

5.

6. The water-based coating for paper modification according to any one of claims 1 to 3 or 5, characterized in that, In the water-based coating, the film-forming agent has a mass percentage content of 8% to 15%. And / or, in the water-based coating, the crosslinking agent has a mass percentage content of 0.5% to 3%.

7. A method for preparing a water-based coating for paper modification, characterized in that, Includes the following steps: 5-20 parts by weight of film-forming agent, 0.5-3 parts by weight of crosslinking agent, 0.7-12 parts by weight of additives, and 75-95 parts by weight of water are mixed to obtain a water-based coating for paper modification. The film-forming agent is selected from at least one of modified polyurethane, acrylic-polyurethane hybrid resin, and bio-based polyurethane.

8. The method for preparing water-based coatings for paper modification according to claim 7, characterized in that, The mixing process includes the following steps: The film-forming agent is added to a first portion of water for a first mixing process to obtain a first premixed solution. The additive is mixed with a second portion of water to obtain a second premixed solution. The first premixed solution and the second premixed solution are subjected to a third mixing treatment, and the pH value is adjusted to 7.0~8.5 to obtain a mixture; Eight hours before use, a crosslinking agent is added to the mixture for a fourth mixing treatment to obtain the water-based coating.

9. A coating characterized in that it is prepared by using an aqueous coating as described in any one of claims 1 to 6 and / or an aqueous coating prepared by the method described in any one of claims 7 to 8.

10. A modified tipping paper, characterized in that, The modified tipping paper includes a tipping paper body and a coating as described in claim 9, which is compounded with the tipping paper body. The preparation method of the modified tipping paper includes the following steps: The water-based coating is applied to the surface of the tipping paper using online micro-grooved roller coating technology, with a wet weight of 1 g / m². 2 ~3g / m 2 ; Dry at 60~80℃ or cure with ultraviolet light for 5~10 seconds.

Images