A high-fixity cigarette tipping paper and its preparation method

Abstract

This invention discloses a high-fixity cigarette tipping paper and its preparation method, belonging to the technical field of tobacco packaging materials. The tipping paper includes a substrate and a high-fixity ink layer. The ink layer is constructed based on an aqueous acrylic resin emulsion and a chitosan and citric acid composite fixation system. A three-dimensional cross-linked network is formed between specific functional groups on the surface of organic pigments and the composite system, achieving both anchoring and cross-linking between the pigments and the substrate. This invention effectively solves the problems of poor color fixation, difficulty in balancing breathability and soft touch, safety hazards, and narrow substrate compatibility of traditional tipping papers. The finished product has stable color fixation, no harmful residues, a comfortable touch, and good breathability. It is compatible with conventional printing equipment and various substrates, meeting the needs of high safety, low cost, and large-scale production. It is suitable for various cigarette packaging scenarios, providing a superior solution for tobacco packaging materials.

Description

Technical Field

[0001] This invention relates to the field of tobacco packaging materials technology, and in particular to a high-fixity cigarette tipping paper and its preparation method. Background Technology

[0002] As a core component of cigarette packaging, tipping paper comes into direct contact with the consumer's mouth and must be compatible with high-speed cigarette rolling processes. It also faces high-humidity environments during storage, transportation, and use. Therefore, its colorfastness, user experience, safety standards, and compatibility are all key indicators of concern to the industry. However, existing tipping paper technology still has many unresolved issues, making it difficult to meet the dual needs of cigarette production and consumption.

[0003] In terms of color fixation performance, traditional cigarette tipping paper is mostly printed with ordinary solvent-based or water-based inks. The pigment molecules in the ink only adhere to the substrate surface through physical adsorption, lacking stable chemical bonding force, resulting in loose bonding between the pigment and the substrate.

[0004] This defect directly leads to a series of problems: during consumer use, the ink is prone to color migration due to saliva contact and finger friction, contaminating the filter or the consumer's fingers; when stored or transported in environments with high relative humidity, the printed pattern is prone to fading and smudging; during the processing of high-speed cigarette machines with a cigarette rolling rate of 8000-12000 cigarettes / min, the ink layer may also fall off due to mechanical friction, affecting the consistency of the appearance of cigarette products. Some technologies have attempted to improve the color fixation effect by increasing the thickness of the ink coating, but have failed to fundamentally improve the bonding method between the pigment and the substrate, resulting in limited improvement in color fixation performance and failing to solve the color migration problem under extreme environments.

[0005] In terms of overall performance balance, existing technologies exhibit significant performance contradictions. On the one hand, the thickened ink coating, designed to improve colorfastness, can clog the gaps between the paper fibers, leading to a significant decrease in paper permeability. This, in turn, affects the stability of cigarette draw resistance and reduces the consumer's smoking experience. At the same time, the thick coating can harden the paper's texture, contradicting the need for soft and conformable tipping paper. On the other hand, while some high-end colorfastness technologies can improve ink adhesion to a certain extent, harmful monomers are easily left behind during the curing process, failing to meet the safety standards for food contact materials and posing potential safety hazards. Furthermore, existing technologies struggle to achieve a multi-dimensional performance balance of high colorfastness, high permeability, soft touch, and high safety simultaneously, often resulting in trade-offs and limiting the market application of the products.

[0006] In terms of practicality and cost control, existing improved color-fixing technologies have significant shortcomings. Some solutions rely on expensive special color-fixing agents or special resin raw materials, which leads to a substantial increase in raw material costs and is not conducive to large-scale promotion. Some processes require special printing and curing equipment, which is incompatible with the existing flexographic and gravure printing production lines of cigarette companies, requiring additional investment in equipment modification costs and increasing the production threshold. At the same time, existing water-based color-fixing inks generally have insufficient stability, and are prone to stratification and sedimentation during storage. The storage period is usually no more than 3 months, which seriously affects the continuity of production. The problems of uneven pigment dispersion and insufficient cross-linking of components during ink preparation also further lead to product quality fluctuations and reduce the feasibility of large-scale production.

[0007] Therefore, this application proposes a high-fixity cigarette tipping paper and its preparation method. Summary of the Invention

[0008] One objective of this invention is to provide a high-fixation cigarette tipping paper and its preparation method. This invention solves the problem of loose bonding between pigments and substrate in traditional cigarette tipping paper, enabling printed patterns to maintain low fading rates and excellent color fixation even under high-speed cigarette rolling and high-humidity environments. Simultaneously, it balances the breathability and soft feel of the finished tipping paper, abandoning potentially harmful UV curing processes and using a safe and environmentally friendly water-based raw material system with no harmful monomer residues. This achieves a four-dimensional performance balance of high color fixation, high breathability, soft feel, and high safety. Furthermore, the composite system synergistically replaces expensive dedicated color-fixing agents, is compatible with conventional printing equipment, and, with a stable ink formulation design, reduces production costs and improves the feasibility of large-scale production. In addition, it is widely compatible with various substrates such as ordinary tipping paper, metallized transfer paper, and anti-permeability base paper. By flexibly adjusting the raw material ratio and coating parameters, it meets the usage needs of different grades of cigarettes, broadening the application scenarios and market adaptability of tipping paper.

[0009] According to an embodiment of the present invention, a high-fixity cigarette tipping paper includes a substrate and a high-fixity ink layer coated on the surface of the substrate. The high-fixation ink layer is constructed based on a water-based acrylic resin emulsion and a chitosan and citric acid composite fixation system. The raw materials for preparing the high-fixity ink, by mass parts, include 20 to 45 parts of water-based acrylic resin emulsion, 20 to 58 parts of chitosan and citric acid mixed solution, 5 to 25 parts of organic pigment, 2 to 10 parts of water-based dye, 1 to 4 parts of polyvinyl alcohol, 1 to 2 parts of glycerol, 1 to 2 parts of wetting and dispersing agent, 0 to 2 parts of pH adjuster, and 25 to 40 parts of solvent; The composite color-fixing system forms a three-dimensional cross-linked network through the functional groups of organic pigments, water-based acrylic resin emulsion, chitosan, and citric acid. This allows the tipping paper to achieve a printing pattern fading rate of ≤5% and a color migration level of ≥4 when processed on a high-speed cigarette machine with a cigarette rate of 8000-12000 cigarettes / min and used in a high humidity environment with a relative humidity of 50%-80%. The paper also has an air permeability of ≥30CU, a soft touch without hardening, and meets the safety standards for food contact materials.

[0010] Furthermore, the raw materials for preparing the high-fixity ink, by mass parts, are preferably 25-40 parts of water-based acrylic resin emulsion, 25-50 parts of chitosan-citric acid mixed solution, 8-20 parts of organic pigment, 3-8 parts of water-based dye, 1.5-3 parts of polyvinyl alcohol, 1.2-1.8 parts of glycerin, 1.2-1.8 parts of wetting and dispersing agent, 0.5-1.5 parts of pH adjuster, and 28-35 parts of solvent.

[0011] Furthermore, the organic pigment is selected from one or more of phthalocyanine blue, phthalocyanine green, azo red, azo yellow, and quinacridone violet, and the total molar percentage of hydroxyl, carboxyl, sulfonyl, and amino groups in the organic pigment is 5%-20% of the total molar number of the organic pigment, and the particle size of the organic pigment is 0.1μm to 1μm.

[0012] Furthermore, the raw materials for preparing the chitosan and citric acid mixed solution include chitosan and citric acid, wherein the molecular weight of chitosan is 50,000 to 500,000 Da, the degree of deacetylation is ≥85%, and the mass ratio of citric acid to chitosan is 1:3 to 1:8; the mixed solution is prepared by adding chitosan and citric acid to a portion of the solvent, stirring and dissolving at 60 to 75°C for 30 to 60 minutes, and then cooling to room temperature, and the mixed solution is in a uniform and clear state, with a pH value between 4.8 and 5.5, and no stratification occurs after standing for 72 hours.

[0013] Furthermore, the solid content of the aqueous acrylic resin emulsion is 30% to 45%, the glass transition temperature is -10℃ to 25℃, the hydroxyl value of the acrylic resin in the emulsion is 20 to 50 mg KOH / g, and the absolute value of the Zeta potential of the emulsion is ≥30 mV.

[0014] Furthermore, the preparation method of the high-fixity ink is as follows: First, weigh each raw material according to the mass fraction. Mix the water-based acrylic resin emulsion, organic pigment, wetting and dispersing agent and 1 / 2 to 2 / 3 of the solvent, put them into the grinding equipment, and grind them at a speed of 1500 to 2500 r / min for 30 to 90 minutes until the particle size of the material is ≤5μm to obtain ink semi-finished product A. Subsequently, chitosan and citric acid mixed solution, aqueous dye, polyvinyl alcohol, glycerin, pH adjuster and remaining solvent are mixed and stirred at 300-500 r / min for 20-40 min at 30-50℃ until polyvinyl alcohol is completely dissolved to obtain ink semi-finished product B. Finally, ink semi-finished product A and ink semi-finished product B are stirred at room temperature at a speed of 400-600 r / min for 15-30 min. After being mixed evenly, the mixture is filtered through a 100-200 mesh filter to obtain the high-fixation ink.

[0015] Furthermore, the pH adjuster is selected from one or more of citric acid, acetate-sodium acetate buffer, and citrate-sodium citrate buffer; The wetting and dispersing agent is a polycarboxylate dispersant or a polyoxyethylene ether dispersant; the solvent is a mixture of deionized water and ethanol, wherein ethanol accounts for 5% to 15% of the total mass of the solvent.

[0016] Furthermore, the substrate comprises a base paper layer and a high-fixity ink layer stacked sequentially. The basis weight of the base paper layer is 25-40 g / m², the air permeability is 30-100 CU, and the surface roughness Ra≤1.5 μm. The base paper layer material is selected from ordinary cork paper, aluminized transfer paper, coated transfer paper, high-gloss base paper, anti-permeability base paper, or high-pressure base paper, and the water absorption height (30 min) of the base paper layer is ≤5 mm.

[0017] Furthermore, when the high-fixity ink is coated onto the substrate surface, flexographic printing or gravure printing is used, and the ink viscosity on the machine during the coating process is 11s to 17s, and the coating dry weight is 0.6g / m² to 0.9g / m². The drying process adopts a segmented drying process. The first stage drying temperature is 60-65℃, the second stage drying temperature is 70-80℃, the total drying time is 5-30s, the machine speed is controlled at 90-120m / min, and the crosslinking degree of the ink layer after drying is ≥85%.

[0018] A method for preparing high-fixity cigarette tipping paper includes the following steps: S1. Select the base paper material that meets the requirements, and remove surface dust and impurities through dust removal equipment to ensure that there are no obvious stains on the surface of the base paper. S2. Inject the prepared high-fixity ink into the ink trough of the printing and coating equipment, adjust the equipment parameters, and evenly coat the high-fixity ink onto the preset surface of the base paper layer. S3. Send the coated paper into the drying device for segmented drying to ensure that the ink layer is completely dry and there is no residual solvent. S4. Feed the dried paper into the slitting equipment and slit it to a width of 50-80mm at a slitting speed of 80-120m / min to ensure that the cut is flat, burr-free, and free of adhesion. S5. Feed the slit paper into the rewinding equipment, control the rewinding tension to be 50-150N and the roll diameter to be 150-300mm. After rewinding, conduct appearance inspection and performance testing. If qualified, the finished high-fixation cigarette tipping paper is obtained.

[0019] The beneficial effects of this invention are: 1. In this invention, functional groups such as hydroxyl, carboxyl, sulfonyl or amino groups on the surface of organic pigments are used to form a stable three-dimensional cross-linking network with the hydroxyl groups of waterborne acrylic resin, the amino groups of chitosan and the carboxyl groups of citric acid. This enables the pigment molecules to form a dual bond of anchoring and cross-linking with the substrate and resin, thus completely solving the problem of loose bonding between pigments and substrates in traditional color fixing technology.

[0020] 2. In this invention, the dense and uniform three-dimensional cross-linked network structure improves colorfastness without clogging the gaps between the base paper fibers. Combined with precise control of the basis weight and air permeability of the base paper layer, the air permeability of the finished tipping paper is ≥30CU, meeting the requirements for stable cigarette draw resistance. Secondly, the glass transition temperature of the water-based acrylic resin emulsion works synergistically with the plasticizing effects of glycerol and polyvinyl alcohol to ensure that the ink layer is soft and does not harden, with a touch close to that of the base paper itself, thus resolving the contradiction between colorfastness and soft touch. At the same time, it abandons potentially harmful processes such as UV curing and selects chitosan, citric acid and water-based raw materials, with no harmful monomer residues, meeting the safety standards for food contact materials, and achieving a four-dimensional balance of high colorfastness, high air permeability, soft touch and high safety.

[0021] 3. In this invention, the synergistic effect of the composite system replaces the expensive special color-fixing agent, reducing raw material costs. The ink preparation involves a step-by-step operation of grinding semi-finished product A and dissolving semi-finished product B, ensuring uniform pigment dispersion and full cross-linking of components. During the coating process, the viscosity, coating dryness, and segmented drying parameters are controlled, making it compatible with conventional equipment such as flexographic printing and gravure printing, without the need for additional dedicated production lines. In addition, the pH control and stability design of the chitosan and citric acid mixed solution ensure that the ink has a shelf life of ≥6 months, solving the problems of easy separation and poor stability of water-based inks, and further improving the feasibility of large-scale production.

[0022] 3. Based on the strong adhesion characteristics of the three-dimensional cross-linked network, this invention achieves wide compatibility with various substrates. Whether it is ordinary tipping paper, aluminized transfer paper, coated transfer paper, high-gloss base paper, anti-permeability base paper, or high-pressure base paper, the high-fixation ink layer can form a stable bond with the substrate surface through functional group cross-linking, without peeling or edge curling. At the same time, by adjusting the ink raw material ratio and coating parameters according to the characteristics of different substrates, excellent color fixation effect can be achieved. This technology can meet the cost control requirements of ordinary cigarettes and also adapt to the requirements of high-end cigarettes for substrate diversity and appearance texture, thus broadening the application scenarios of tipping paper and enhancing the universality and market value of the technology. Attached Figure Description

[0023] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of a high-fixity cigarette tipping paper proposed in this invention; Figure 2 This is a flowchart illustrating the preparation method of a high-fixity cigarette tipping paper proposed in this invention. Detailed Implementation

[0024] To make the technical means and objectives and effects of the present invention easier to understand, the embodiments of the present invention will be described in detail below with reference to specific illustrations.

[0025] The high-fixation cigarette tipping paper of the present invention includes a substrate and a high-fixation ink layer coated on the surface of the substrate. The substrate consists of a base paper layer and a high-fixation ink layer stacked sequentially. The high-fixation ink layer is constructed based on an aqueous acrylic resin emulsion and a chitosan and citric acid composite fixation system. This composite fixation system forms a three-dimensional cross-linked network through the functional groups of organic pigments, the aqueous acrylic resin emulsion, chitosan, and citric acid. This allows the tipping paper to maintain excellent fixation performance even under high-speed cigarette machine processing and high humidity environments, while also taking into account the paper's air permeability and soft touch, and meeting the safety standards for food contact materials.

[0026] Example 1:

[0027] like Figure 1 As shown, the present invention discloses a high-fixity cigarette tipping paper, comprising a substrate and a high-fixity ink layer coated on the surface of the substrate; The raw materials for preparing high-fixity ink, by mass, are 30 parts of water-based acrylic resin emulsion, 35 parts of chitosan and citric acid mixed solution, 15 parts of organic pigment, 5 parts of water-based dye, 2 parts of polyvinyl alcohol, 1.5 parts of glycerin, 1.5 parts of wetting and dispersing agent, 1 part of pH adjuster, and 32 parts of solvent.

[0028] The organic pigment is selected from a compound of phthalocyanine blue and azo red, with a mass ratio of 1:1. The total molar percentage of hydroxyl, carboxyl, sulfonyl and amino groups in the organic pigment is 12% of the total molar percentage of the organic pigment, and its particle size is 0.5 μm as determined by a laser particle size analyzer.

[0029] The raw materials for preparing the chitosan and citric acid mixed solution are chitosan and citric acid. The molecular weight of chitosan is 200,000 Da and the degree of deacetylation is 90%. The mass ratio of citric acid to chitosan is 1:5. During preparation, chitosan and citric acid were added to 10 parts of solvent, stirred and dissolved at 65°C for 45 min, and then cooled to room temperature. The resulting mixed solution was homogeneous and clear, and its pH value was measured to be 5.2 using a pH meter. After the solution was left to stand for 72 h, no stratification was observed.

[0030] The solid content of the waterborne acrylic resin emulsion is 38%, which meets the range of 30%-45% as determined by the drying loss method; the glass transition temperature is 10℃, which meets the requirement of -10℃-25℃ as determined by differential scanning calorimetry; the hydroxyl value of the acrylic resin in the emulsion is 35mgKOH / g, which meets the requirement of 50-80mgKOH / g as determined by GB / T12008.3-2009 standard; the absolute value of the zeta potential of the emulsion is 35mV, which meets the requirement of ≥30mV as determined by a zeta potential meter.

[0031] The pH adjuster is a citrate-sodium citrate buffer solution, the wetting and dispersing agent is a polycarboxylate dispersant, and the solvent is a mixture of deionized water and ethanol, in which ethanol accounts for 10% of the total solvent mass, which meets the requirement of 5%-15%.

[0032] The preparation of high-fixity inks is carried out according to the following steps: First, weigh each raw material according to the above-mentioned mass proportions. Mix 30 parts of water-based acrylic resin emulsion, 15 parts of organic pigment, 1.5 parts of wetting and dispersing agent and 2 / 3 of the solvent, put them into a sand mill, and grind them at a speed of 2000 r / min for 60 min. The particle size of the material is detected by a laser particle size analyzer and is 2.8 μm (≤5 μm), thus obtaining ink semi-finished product A. Subsequently, 35 parts of chitosan and citric acid mixed solution, 5 parts of water-based dye, 2 parts of polyvinyl alcohol, 1.5 parts of glycerol, 1 part of pH adjuster and the remaining 1 / 3 of solvent were mixed and stirred at 400 r / min for 30 min at 40℃. The polyvinyl alcohol was completely dissolved by visual observation to obtain ink semi-finished product B. Finally, ink semi-finished product A and ink semi-finished product B were stirred at 500 r / min for 20 min at room temperature. After being mixed evenly, they were filtered through a 150 mesh filter to remove impurities and obtain high-fixation ink.

[0033] The base paper layer in the substrate is ordinary cork paper with a basis weight of 30 g / m², an air permeability of 60 CU, a surface roughness Ra of 1.2 μm as measured by a roughness tester, and a water absorption height (30 min) of 3 mm (≤5 mm).

[0034] When preparing tipping paper, such as Figure 2 As shown, the first step S1 is to remove surface dust and impurities from the selected ordinary cork paper using a pulse dust removal device, and visually inspect it to ensure that there are no obvious stains on the surface of the original paper layer. Next, proceed to step S2: inject the prepared high-fixity ink into the ink trough of the flexographic printing equipment, adjust the equipment parameters so that the ink viscosity on the machine is 14s (Coil 4 cup, 25℃, within the range of 11s-17s), and the coating dry weight is controlled to be 0.75g / m² (meeting the requirements of 0.6g / m²-0.9g / m²), and uniformly coat the high-fixity ink on the preset surface of the base paper layer; Then, proceed to step S3: send the coated paper into a tunnel drying device for segmented drying. The drying temperature of the first segment is set to 62℃, the drying temperature of the second segment is set to 75℃, the total drying time is 20s, the machine speed is controlled at 75m / min, and the crosslinking degree of the ink layer after drying is tested by a crosslinking degree tester to be 90% (≥85%). At the same time, the ink layer is tested according to the standard to find no residual solvent. Next, proceed to step S4: feed the dried paper into the slitting equipment and slit it to a width of 30mm. Set the slitting speed to 100m / min. After inspection, the cut is smooth, without burrs or adhesion. Finally, step S5 is executed: the slit paper is fed into the rewinding equipment, the rewinding tension is controlled at 100N and the roll diameter is 200mm. After rewinding, the finished product is subjected to appearance inspection and performance testing. The appearance inspection shows no defects such as bubbles, scratches, or color difference. The performance test shows that the fading rate of the printed pattern is 2.8% (≤5%), the color migration level is 4.8 (≥4) according to the standard test, the paper air permeability is 35CU (≥30CU) according to the standard test, and the paper feels soft and does not harden. At the same time, the paper meets the safety standards for food contact materials according to the standard test.

[0035] This embodiment, through optimized raw material ratios and process parameters, makes the three-dimensional cross-linked network structure of the composite color-fixing system more stable. Even in the high-speed cigarette machine processing scenario of 75m / min, it can still ensure uniform adhesion of the ink layer. Even when used in a high humidity environment with a relative humidity of 50%-80%, it can effectively prevent the printed pattern from fading, migrating, or bleeding. At the same time, it takes into account the air permeability and soft touch of the paper, completely solving the problem that traditional tipping paper is difficult to balance color fixation and user experience. Moreover, there are no harmful monomer residues, which fully meet the safety requirements of food contact materials.

[0036] Example 2:

[0037] The raw materials for preparing the high-fixity ink, by mass, are: 25 parts water-based acrylic resin emulsion, 25 parts chitosan and citric acid mixed solution, 8 parts organic pigment, 3 parts water-based dye, 1.5 parts polyvinyl alcohol, 1.2 parts glycerol, 1.2 parts wetting and dispersing agent, 0.5 parts pH adjuster, and 28 parts solvent. The organic pigment selected is azo yellow, with a total molar ratio of hydroxyl and carboxyl groups of 5% of the total molar amount of organic pigment, and a particle size of 0.1 μm.

[0038] In the chitosan and citric acid mixed solution, the chitosan has a molecular weight of 50,000 Da and a degree of deacetylation of 85%, and the mass ratio of citric acid to chitosan is 1:3. During preparation, chitosan and citric acid were added to 8 parts of solvent, stirred and dissolved at 60°C for 30 min, and then cooled to room temperature. The resulting mixed solution had a pH of 4.8 and did not separate into layers after standing for 72 h.

[0039] The waterborne acrylic resin emulsion has a solid content of 30%, a glass transition temperature of -10℃, a hydroxyl value of 20 mg KOH / g, and an absolute Zeta potential of 30 mV. The pH adjuster is an acetate-sodium acetate buffer solution, the wetting and dispersing agent is a polyoxyethylene ether dispersant, and the solvent is a mixture of deionized water and ethanol, with ethanol accounting for 5% of the total solvent mass.

[0040] Preparation steps of high-fixity inks: A water-based acrylic resin emulsion, organic pigment, wetting and dispersing agent and 1 / 2 solvent are mixed and put into a grinding equipment and ground at a speed of 1500 r / min for 30 min. The particle size of the material is 4.5 μm, and ink semi-finished product A is obtained. Chitosan and citric acid mixed solution, aqueous dye, polyvinyl alcohol, glycerin, pH adjuster and remaining solvent were mixed and stirred at 300 r / min for 20 min at 30℃. After the polyvinyl alcohol was completely dissolved, ink semi-finished product B was obtained. The two were stirred at 400 r / min for 15 min at room temperature and filtered through a 100 mesh filter to obtain high color fastness ink.

[0041] The base paper layer of the substrate is made of aluminized transfer paper with a basis weight of 25 g / m², an air permeability of 30 CU, a surface roughness Ra=1.0 μm, and a water absorption height (30 min) of 2 mm.

[0042] During tipping paper preparation, S1, impurities on the surface of the base paper are removed using a dust removal device; S2. The ink is applied using gravure printing, with an on-machine viscosity of 11s and a coating dry weight of 0.6g / m². S3, the segmented drying temperature is 60℃ and 70℃, the total drying time is 10s, the machine speed is 70m / min, and the ink layer crosslinking degree is 85%; S4. Cut to a width of 20mm at a cutting speed of 80m / min; S5, rewinding tension 50N, roll diameter 150mm, finished product appearance inspection qualified, performance test fading rate 3.5%, color migration level 4.2, air permeability 32CU, soft touch, meets food contact material safety standards.

[0043] This embodiment uses a low proportion of raw materials and mild process parameters to achieve excellent color fixation while controlling production costs. The machine speed of 70m / min is suitable for medium- and high-speed cigarette production. The aluminized transfer paper substrate and the high color fixation ink layer are well compatible with each other, with no peeling. Even in the case of saliva contact or friction, there is no color migration to the filter or fingers. The paper's air permeability meets the requirements of cigarette draw resistance, and it is soft to the touch without hardening. At the same time, it avoids the harmful residues that may be caused by processes such as ultraviolet curing, and its safety performance meets the standards. It is suitable for large-scale production scenarios with certain requirements for cost control.

[0044] Example 3:

[0045] The raw materials for preparing high-fixity ink, by mass, are: 40 parts of water-based acrylic resin emulsion, 50 parts of chitosan and citric acid mixed solution, 20 parts of organic pigment, 8 parts of water-based dye, 3 parts of polyvinyl alcohol, 1.8 parts of glycerin, 1.8 parts of wetting and dispersing agent, 1.5 parts of pH adjuster, and 35 parts of solvent.

[0046] The organic pigment is a compound of quinacridone violet and phthalocyanine green in a mass ratio of 1:1, with a total molar percentage of 20% functional groups and a particle size of 1.0 μm.

[0047] Chitosan has a molecular weight of 500,000 Da and a degree of deacetylation of 95%. The mass ratio of citric acid to chitosan is 1:8. When preparing the mixed solution, 12 parts of solvent are added, and the mixture is stirred at 75°C for 60 min. After cooling, the pH is 5.5, and no stratification occurs after standing for 72 h.

[0048] The waterborne acrylic resin emulsion has a solid content of 45%, a glass transition temperature of 25℃, a hydroxyl value of 50mgKOH / g, and an absolute value of 38mV for the zeta potential.

[0049] The pH adjuster is citric acid, the wetting and dispersing agent is polycarboxylate dispersant, and ethanol accounts for 15% of the solvent.

[0050] Preparation of high-fixity ink: water-based acrylic resin emulsion, organic pigment, wetting and dispersing agent and 2 / 3 solvent are mixed and ground at 2500 r / min for 90 min, with a particle size of 2.0 μm, to obtain semi-finished product A; Chitosan-citric acid mixed solution, aqueous dye, polyvinyl alcohol, glycerol, pH adjuster and remaining solvent are mixed and stirred at 50℃ and 500r / min for 40min to obtain semi-finished product B; The two materials were stirred at 600 rpm for 30 minutes and then filtered through a 200-mesh filter to obtain ink.

[0051] The base paper layer uses impermeable base paper with a basis weight of 40 g / m², an air permeability of 100 CU, a surface roughness of Ra=1.5 μm, and a water absorption height (30 min) of 5 mm.

[0052] Tipping paper preparation: S1. Dust removal treatment; S2, flexographic printing coating, on-machine viscosity 17s, coating dry weight 0.9g / m²; S3, segmented drying temperatures 65℃ and 80℃, total drying time 30s, machine speed 85m / min, ink layer crosslinking degree 92%; S4. Cut to a width of 50mm at a cutting speed of 120m / min; S5. Rewinding tension of 150N, roll diameter of 300mm, finished product fading rate of 4.2%, color migration grade of 4.5, air permeability of 38CU, soft touch, and meets the safety standards for food contact materials.

[0053] This embodiment employs a high proportion of raw materials and high-intensity process parameters, achieving a 92% cross-linking degree in the ink layer and superior color-fixing performance. The high-speed processing of 85m / min is perfectly suited to the production efficiency of mainstream high-speed cigarette machines. The selection of an impermeable base paper further enhances the humidity resistance of the tipping paper, maintaining clear printing patterns without smudging even in extreme high-humidity environments of 95% relative humidity. Simultaneously, the synergistic effect of the high-solids-content waterborne acrylic resin emulsion and the chitosan-citric acid composite system ensures both the adhesion strength of the ink layer and prevents paper hardening. The air permeability of 38CU exceeds the minimum requirement, ensuring stable cigarette draw resistance. This solution is suitable for high-end cigarette packaging scenarios with high requirements for color-fixing performance and processing efficiency, and it contains no harmful additives throughout the process, meeting stringent safety standards for food contact materials.

[0054] The technical solutions of the present invention are fully disclosed through specific raw material ratios, process operations and performance test data in the above embodiments, ensuring that those skilled in the art can accurately reproduce the high color-fixation cigarette tipping paper of the present invention according to the above specific embodiments, and the products obtained can meet the requirements of high-speed cigarette machine processing and use in high humidity environments, effectively solving the problems of poor color fixation, insufficient air permeability and hardened touch of traditional tipping paper.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A tipping paper for high-fixity cigarettes, characterized in that, Includes a substrate and a high-fixation ink layer coated on the surface of the substrate; The high-fixation ink layer is constructed based on a water-based acrylic resin emulsion and a chitosan and citric acid composite fixation system. The raw materials for preparing the high-fixity ink, by mass parts, include 20 to 45 parts of water-based acrylic resin emulsion, 20 to 58 parts of chitosan and citric acid mixed solution, 5 to 25 parts of organic pigment, 2 to 10 parts of water-based dye, 1 to 4 parts of polyvinyl alcohol, 1 to 2 parts of glycerol, 1 to 2 parts of wetting and dispersing agent, 0 to 2 parts of pH adjuster, and 25 to 40 parts of solvent; The composite color-fixing system forms a three-dimensional cross-linked network through the functional groups of organic pigments, water-based acrylic resin emulsion, chitosan, and citric acid. This allows the tipping paper to achieve a printing pattern fading rate of ≤5% and a color migration level of ≥4 when processed on a high-speed cigarette machine with a cigarette rate of 8000-12000 cigarettes / min and used in a high humidity environment with a relative humidity of 50%-80%. The paper also has an air permeability of ≥30CU, a soft touch without hardening, and meets the safety standards for food contact materials.

2. The high-fixity cigarette tipping paper according to claim 1, characterized in that, The raw materials for preparing the high-fixation ink, by mass parts, are preferably 25-40 parts of water-based acrylic resin emulsion, 25-50 parts of chitosan-citric acid mixed solution, 8-20 parts of organic pigment, 3-8 parts of water-based dye, 1.5-3 parts of polyvinyl alcohol, 1.2-1.8 parts of glycerin, 1.2-1.8 parts of wetting and dispersing agent, 0.5-1.5 parts of pH adjuster, and 28-35 parts of solvent.

3. The high-fixity cigarette tipping paper according to claim 2, characterized in that, The organic pigment is selected from one or more of phthalocyanine blue, phthalocyanine green, azo red, azo yellow, and quinacridone violet, and the total molar percentage of hydroxyl, carboxyl, sulfonyl and amino groups in the organic pigment is 5%-20% of the total molar number of the organic pigment, and the particle size of the organic pigment is 0.1μm to 1μm.

4. The high-fixity cigarette tipping paper according to claim 2, characterized in that, The raw materials for preparing the chitosan and citric acid mixed solution include chitosan and citric acid. The chitosan has a molecular weight of 50,000 to 500,000 Da and a degree of deacetylation ≥ 85%. The mass ratio of citric acid to chitosan is 1:3 to 1:

8. The mixed solution is prepared by adding chitosan and citric acid to a portion of the solvent, stirring and dissolving at 60 to 75°C for 30 to 60 minutes, and then cooling to room temperature. The mixed solution is homogeneous and clear, with a pH value between 4.8 and 5.5, and shows no stratification after standing for 72 hours.

5. The high-fixity cigarette tipping paper according to claim 1, characterized in that, The aqueous acrylic resin emulsion has a solid content of 30% to 45%, a glass transition temperature of -10℃ to 25℃, a hydroxyl value of 20 to 50 mgKOH / g for the acrylic resin in the emulsion, and an absolute value of zeta potential ≥ 30 mV.

6. The high-fixity cigarette tipping paper according to claim 2, characterized in that, The preparation method of the high-fixity ink is as follows: First, weigh each raw material according to the mass fraction. Mix the water-based acrylic resin emulsion, organic pigment, wetting and dispersing agent and 1 / 2 to 2 / 3 of the solvent, put them into the grinding equipment, and grind them at a speed of 1500 to 2500 r / min for 30 to 90 minutes until the particle size of the material is ≤5μm to obtain ink semi-finished product A. Subsequently, chitosan and citric acid mixed solution, aqueous dye, polyvinyl alcohol, glycerin, pH adjuster and remaining solvent are mixed and stirred at 300-500 r / min for 20-40 min at 30-50℃ until polyvinyl alcohol is completely dissolved to obtain ink semi-finished product B. Finally, ink semi-finished product A and ink semi-finished product B are stirred at room temperature at a speed of 400-600 r / min for 15-30 min. After being mixed evenly, the mixture is filtered through a 100-200 mesh filter to obtain the high-fixation ink.

7. The high-fixity cigarette tipping paper according to claim 1, characterized in that, The pH adjuster is selected from one or more of citric acid, acetate-sodium acetate buffer, and citrate-sodium citrate buffer. The wetting and dispersing agent is a polycarboxylate dispersant or a polyoxyethylene ether dispersant; the solvent is a mixture of deionized water and ethanol, wherein ethanol accounts for 5% to 15% of the total mass of the solvent.

8. The high-fixity cigarette tipping paper according to claim 1, characterized in that, The substrate comprises a base paper layer and a high-fixity ink layer stacked sequentially. The basis weight of the base paper layer is 25-40 g / m², the air permeability is 30-100 CU, and the surface roughness Ra≤1.5 μm. The base paper layer material is selected from ordinary cork paper, aluminized transfer paper, coated transfer paper, high-gloss base paper, anti-permeability base paper, or high-pressure base paper, and the water absorption height (30 min) of the base paper layer is ≤5 mm.

9. The high-fixity cigarette tipping paper according to claim 1, characterized in that, When the high-fixity ink is coated onto the substrate surface, flexographic or gravure printing is used. During the coating process, the ink viscosity on the machine is 11s to 17s, and the coating dry weight is 0.6g / m² to 0.9g / m². The drying process adopts a segmented drying process. The first stage drying temperature is 60-65℃, the second stage drying temperature is 70-80℃, the total drying time is 5-30s, the machine speed is controlled at 90-120m / min, and the crosslinking degree of the ink layer after drying is ≥85%.

10. A method for preparing high-fixity cigarette tipping paper, as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Select the base paper material that meets the requirements, and remove surface dust and impurities through dust removal equipment to ensure that there are no obvious stains on the surface of the base paper. S2. Inject the prepared high-fixity ink into the ink trough of the printing and coating equipment, adjust the equipment parameters, and evenly coat the high-fixity ink onto the preset surface of the base paper layer. S3. Send the coated paper into the drying device for segmented drying to ensure that the ink layer is completely dry and there is no residual solvent. S4. Feed the dried paper into the slitting equipment and slit it to a width of 50-80mm at a slitting speed of 80-120m / min to ensure that the cut is flat, burr-free, and free of adhesion. S5. Feed the slit paper into the rewinding equipment, control the rewinding tension to be 50-150N and the roll diameter to be 150-300mm. After rewinding, conduct appearance inspection and performance testing. If qualified, the finished high-fixity cigarette tipping paper is obtained.

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