An environmentally friendly ink and printing process for cigarette label paper

Abstract

This application discloses an environmentally friendly ink and printing process for cigarette label paper, belonging to the field of environmentally friendly ink technology. By weight, it comprises: 55-60 parts acrylic emulsion, 15-20 parts polyurethane emulsion, 25-30 parts water-based prepolymer, 80-100 parts solvent, 80-100 parts water-based pigment, 2.5-3 parts di(methacryloyloxyethyl) hydrogen phosphate, 4-8 parts scratch-resistant agent, 1-1.5 parts initiator, 2-4 parts defoamer, 2-4 parts stabilizer, 2-4 parts leveling agent, 1-2 parts wax emulsion, 2-3 parts wetting agent, and 0.1-0.5 parts preservative; the water-based prepolymer is obtained by polymerizing acrylamide and a compound with benzene rings and double bonds, and the scratch-resistant agent is modified silica. The addition of water-based prepolymers to this environmentally friendly ink reduces the amount of scratch-resistant agent required. The two work synergistically to improve the ink's abrasion resistance and storage stability, and it is less prone to clogging, thus improving printing efficiency and printing consistency.

Description

Technical Field

[0001] This application relates to an environmentally friendly ink and printing process for cigarette label paper, belonging to the field of environmentally friendly ink technology. Background Technology

[0002] Cigarette label paper is printed with ink. In order to reduce environmental pollution, the industry now has stricter requirements for the environmental protection of cigarette label paper ink. The industry generally uses low-VOC water-based resin as the base and adds water-based pigments and alcohol solvents for printing.

[0003] To further improve the performance of environmentally friendly cigarette inks, current research focuses on enhancing their stability and migration resistance. For example, patent CN117025022A discloses an environmentally friendly cigarette label ink that uses a blend of acrylic resin, polyethylene oxide, and polyethylene methyl ester as the water-based resin matrix. This provides the ink with good film-forming properties and printing adhesion, as well as some heat resistance. However, the additives in this type of existing ink are small amounts of polyethylene wax and grease, resulting in insufficient scratch resistance. Therefore, during the stacking and transportation of finished cigarette packaging products, external scratches can easily cause the ink to fade or expose the substrate. In addition, the ink layer absorbs a small amount of water after contact with human sweat and saliva, which further reduces the ink's scratch resistance and seriously affects the appearance quality of cigarette label paper.

[0004] To improve the scratch resistance of ink, scratch-resistant fillers can be added. However, this method still has the following drawbacks: First, the addition of scratch-resistant fillers can easily clog the print head, resulting in low printing efficiency. Second, scratch-resistant fillers tend to settle in the ink, leading to decreased ink stability. This can cause uneven coloring and large color difference fluctuations during printing, making it difficult to ensure printing consistency.

[0005] Therefore, it is necessary to develop an environmentally friendly ink that can both guarantee scratch resistance and improve printing efficiency and consistency. Summary of the Invention

[0006] To address the aforementioned issues, an environmentally friendly ink for cigarette label paper is provided. The addition of a water-based prepolymer to this ink reduces the amount of scratch-resistant agent required. The two work synergistically to improve the ink's abrasion resistance and storage stability, and it is less prone to clogging, thereby improving printing efficiency and printing consistency.

[0007] According to one aspect of this application, an environmentally friendly ink for cigarette label paper is provided, comprising, by weight: Acrylic emulsion 55-60 parts, polyurethane emulsion 15-20 parts, waterborne prepolymer 25-30 parts, solvent 80-100 parts, waterborne pigment 80-100 parts, di(methacryloyloxyethyl) hydrogen phosphate 2.5-3 parts, scratch resistant agent 4-8 parts, initiator 1-1.5 parts, defoamer 2-4 parts, stabilizer 2-4 parts, leveling agent 2-4 parts, wax emulsion 1-2 parts, wetting agent 2-3 parts, preservative 0.1-0.5 parts; The aqueous prepolymer is obtained by polymerizing acrylamide and a compound with benzene rings and double bonds, and the scratch-resistant agent is modified silica.

[0008] This application adds an aqueous prepolymer as a matrix to acrylic emulsion and polyurethane emulsion as ink matrix. The aqueous prepolymer is polymerized again under the action of an initiator, and di(methacryloyloxyethyl) hydrogen phosphate is used as a crosslinking agent to improve the crosslinking density of the ink matrix, thereby giving the ink good film-forming consistency and adhesion, and reducing the risk of being wiped off by external force.

[0009] In addition, waterborne prepolymers are copolymers of acrylamide and compounds with benzene rings and double bonds. Acrylamide contains a lot of amino groups, which can be well compatible with acrylic emulsions and polyurethane emulsions and form hydrogen bonds to improve the film-forming consistency of inks and reduce the occurrence of printing pinholes or other defects. Compounds with benzene rings and double bonds can introduce rigid structures into prepolymers, which can help improve the scratch resistance of inks. When combined with scratch-resistant agents, the scratch resistance of inks is significantly improved.

[0010] Di(methacryloyloxyethyl) hydrogen phosphate is introduced into the ink crosslinking network as a crosslinking agent, which can improve the ink's resistance to abrasion and swelling by liquids such as sweat, thereby extending the shelf life of printing ink. In addition, di(methacryloyloxyethyl) hydrogen phosphate is well compatible with silica scratch-resistant agents, promoting the dispersion of scratch-resistant agents and thus improving the storage stability of ink.

[0011] Optionally, the weight ratio of the aqueous prepolymer to the di(methacryloyloxyethyl) hydrogen phosphate is 10:1.

[0012] The weight ratio of the two is used to adjust the degree of crosslinking of the prepolymer network. If there is too much di(methacryloyloxyethyl) hydrogen phosphate, the viscosity of the ink will increase, which will easily clog the print head. If there is too little di(methacryloyloxyethyl) hydrogen phosphate, the abrasion resistance and density of the ink will be reduced, and the storage stability of the ink will also decrease.

[0013] Optionally, the weight ratio of the acrylamide to the compound with a benzene ring and double bond is 1:(0.1-0.2).

[0014] The weight ratio of acrylamide and other components in an aqueous prepolymer affects its compatibility with the rest of the ink matrix and the ink's abrasion resistance. At the specified ratio, the hydrophilicity and molecular rigidity of the aqueous prepolymer can be balanced, achieving an optimal balance between abrasion resistance and ink film-forming properties. Excessive acrylamide will decrease the ink's abrasion resistance, while insufficient acrylamide will lead to poor water solubility of the aqueous prepolymer, resulting in poor film-forming consistency and consequently, greater color and thickness variations in printing.

[0015] Optionally, the compound containing a benzene ring and a double bond includes at least one of styrene, methylstyrene, and 4-vinylbiphenyltriazole; the structural formula of the 4-vinylbiphenyltriazole is: .

[0016] The three compounds mentioned above, containing benzene rings and double bonds, can impart good rigidity to water-based prepolymers, thereby improving the heat resistance, scratch resistance, and hardness of the ink. This maximizes the density and scratch resistance of the ink layer while ensuring the rheological properties of the ink. 4-Vinylbibenzothiazole contains two benzene rings and a triazole group. The biphenyl structure further improves the scratch resistance of the ink, while the triazole group provides hydrogen bonding sites, increasing the interaction between the water-based prepolymer and pigments and scratch-resistant agents. This reduces the sedimentation of pigments and scratch-resistant agents, further improving the stability of the ink.

[0017] Optionally, the preparation method of the 4-vinylbiphenyltriazole is as follows: 5-Bromo-1H-benzotriazole and 4-vinylphenylboronic acid in a molar ratio of 1:(1-1.2) were added to a solvent, followed by the addition of potassium carbonate and tetra-triphenylphosphine palladium. The mixture was refluxed at 100°C under an inert gas atmosphere for at least 10 hours. After removing the solvent, the mixture was purified to obtain the final product.

[0018] The above preparation process enables the rapid synthesis of 4-vinylbibenzotriazole, improves product yield, and facilitates the subsequent synthesis of aqueous prepolymers.

[0019] Optionally, the method for preparing the aqueous prepolymer includes the following steps: S1: Acrylamide and compounds with benzene rings and double bonds in a weight ratio of 1:(0.1-0.2) are added to a solvent, followed by the addition of an initiator, and the reaction is carried out at 60-70℃ for 4-5 hours. S2: Filter and remove the solvent to obtain the aqueous prepolymer.

[0020] The above preparation process involves prepolymerization at 60-70℃, which can control the polymerization rate of the prepolymer and ensure uniform copolymerization of acrylamide and compounds with benzene rings and double bonds to obtain a high-purity waterborne prepolymer. The polymerization time can ensure that the long-chain molecular weight of the waterborne prepolymer is moderate, which is convenient for subsequent crosslinking.

[0021] Optionally, the scratch-resistant agent is silicon dioxide obtained by surface modification of epoxy monomers.

[0022] Surface modification of silica with epoxy monomers serves two purposes: first, it reacts with the amino groups on the acrylamide monomers of the waterborne prepolymer, locking the scratch-resistant agent within the cross-linked network of the prepolymer, thus improving its scratch resistance and achieving high scratch resistance at low dosages; second, it has a high affinity for di(methacryloyloxyethyl) hydrogen phosphate, and the phosphohydroxyl groups in di(methacryloyloxyethyl) hydrogen phosphate can also react with the epoxy groups, thereby improving the stability of the scratch-resistant agent during ink storage. These two effects allow the scratch-resistant agent to be uniformly suspended in the ink before cross-linking, reducing sedimentation and improving ink printing consistency. Furthermore, after cross-linking, it anchors itself within the cross-linked network, imparting long-term scratch resistance to the ink.

[0023] Optionally, the method for preparing the scratch-resistant agent is as follows: Aminated silica is placed in a solution of 5-15 wt% diepoxy monomer and stirred at 40-50°C for 2-3 hours. The mixture is then filtered, washed, and dried to obtain the final product.

[0024] A scratch-resistant agent with epoxy groups on the surface is obtained by reacting aminated silica with diepoxy monomers. This ensures the number of epoxy groups on the silica surface, reduces silica agglomeration, and facilitates stable dispersion in inks.

[0025] Optionally, the diepoxy monomer includes at least one of diepoxyglycerol ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, and 1,6-hexanediol diglycidyl ether.

[0026] The aforementioned diepoxy monomers can all achieve epoxidative modification of silica surfaces, thereby improving the storage stability of inks. Since the molecular chain length of the diepoxy monomers affects the density and flexibility of the epoxy groups, which in turn affects the storage performance of the scratch-resistant agent in the ink and its compatibility with the ink matrix, the optimal ratio is: the diepoxy monomers are selected from diepoxyglycerol ether and 1,4-butanediol diglycidyl ether in a weight ratio of 1:2.

[0027] According to another aspect of this application, a printing process is provided for using environmentally friendly inks for cigarette label paper as described in any of the above claims. The process involves mixing the acrylic emulsion, polyurethane emulsion, water-based prepolymer, solvent, water-based pigment, di(methacryloyloxyethyl) hydrogen phosphate, scratch-resistant agent, defoamer, stabilizer, leveling agent, wax emulsion, wetting agent, and preservative to obtain the printing ink. The printing ink is then printed onto cigarette label paper and cured at 60-70°C for 10-15 seconds to obtain the final product.

[0028] The beneficial effects of this application include, but are not limited to: 1. The environmentally friendly ink for cigarette label paper according to this application can improve the hardness of the ink layer and help improve scratch resistance by introducing benzene ring groups in the water-based prepolymer; and improve the ink's resistance to liquid swelling by using di(methacryloyloxyethyl) hydrogen phosphate as a crosslinking agent to construct a dense crosslinking network. Furthermore, both the water-based prepolymer and di(methacryloyloxyethyl) hydrogen phosphate can be combined with epoxidized silica to achieve stable storage of silica scratch-resistant agent in the ink and good anchoring in the crosslinking network, thereby significantly improving the ink's storage stability, printing consistency, scratch resistance, and color uniformity.

[0029] 2. The environmentally friendly ink for cigarette label paper according to this application has good compatibility with water-based prepolymers and acrylic emulsions and polyurethane emulsions, which can improve the consistency of the ink, improve the color consistency of the ink, and avoid the existence of pinhole defects, making it more suitable for mass production printing.

[0030] 3. The environmentally friendly ink for cigarette label paper according to this application has a scratch-resistant agent that is well dispersed in the ink without agglomeration, can prevent sedimentation for a long time, improves the storage stability of the ink, reduces the clogging of the printing head, and improves printing efficiency.

[0031] 4. The environmentally friendly ink for cigarette label paper according to this application can effectively reduce VOCs content, has no heavy metal leaching, and the solvent residue meets the requirements of tobacco packaging, making it more green and environmentally friendly. Detailed Implementation

[0032] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0033] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application were all purchased commercially.

[0034] In the following examples and comparative examples, the solvent is a 15% aqueous ethanol solution, the water-based pigment is iron oxide red, the initiator is ammonium persulfate, the defoamer is BYK-024, the stabilizer is hydroxybenzoate, the leveling agent is BYK-333, the wax emulsion is a polyethylene wax emulsion, the wetting agent is PGME, the preservative is Dowicil 75, and the solid content of acrylic acid in the acrylic emulsion is 50wt%.

[0035] The polyurethane emulsion is a polyurethane emulsion containing long-chain alkyl groups, and the preparation process is as follows: In a reaction vessel, MDI, polyether polyol containing long-chain alkyl groups, polyhexanediol adipate, and co-solvent are mixed and stirred at 80-90℃ for 2-4 hours to obtain a prepolymer; the mass ratio of MDI, polyether polyol containing long-chain alkyl groups, and polyhexanediol adipate is 3:2.5:2.

[0036] The prepolymer is gradually added to the emulsifier solution to form an emulsion under ultrasonic emulsification conditions; the fatty acid salt emulsifier accounts for 10% of the prepolymer mass, and the siloxane emulsifier accounts for 3% of the prepolymer mass.

[0037] Add ethylenediamine to the emulsion at a mass ratio of ethylenediamine to MDI of 1:6, and continue stirring at 50-60°C until the reaction is complete.

[0038] The pH of the product after the reaction was adjusted to neutral, filtered, and the solvent was removed by vacuum distillation to obtain a polyurethane emulsion containing long-chain alkyl groups.

[0039] Unless otherwise specified, the methods used in the embodiments and comparative examples of this application are conventional methods in the prior art.

[0040] Example 1 This embodiment relates to an environmentally friendly ink for cigarette label paper, comprising, by weight: 55 parts acrylic emulsion, 15 parts polyurethane emulsion, 25 parts waterborne prepolymer, 80 parts solvent, 80 parts waterborne pigment, 2.5 parts di(methacryloyloxyethyl) hydrogen phosphate, 4 parts scratch resistant agent, 1 part initiator, 2 parts defoamer, 2 parts stabilizer, 2 parts leveling agent, 1 part wax emulsion, 2 parts wetting agent, and 0.1 parts preservative. The preparation method of the aqueous prepolymer includes the following steps: S1: Acrylamide and styrene in a weight ratio of 1:0.2 were added to a solvent (water and ethanol in a volume ratio of 1:1), followed by the addition of an initiator accounting for 1 wt% of acrylamide, and the reaction was carried out at 70°C for 4 h. S2: Filter and remove the solvent by rotary evaporation to obtain the aqueous prepolymer.

[0041] The preparation method of the scratch-resistant agent is as follows: Aminated silica was placed in a solution of 5 wt% ethylene glycol diglycidyl ether and stirred at 50°C for 2 hours. The mixture was then filtered, washed, and dried to obtain the final product.

[0042] Example 2 This embodiment relates to an environmentally friendly ink for cigarette label paper, comprising, by weight: 60 parts acrylic emulsion, 20 parts polyurethane emulsion, 30 parts water-based prepolymer, 100 parts solvent, 100 parts water-based pigment, 3 parts di(methacryloyloxyethyl) hydrogen phosphate, 8 parts scratch-resistant agent, 1.5 parts initiator, 4 parts defoamer, 4 parts stabilizer, 4 parts leveling agent, 2 parts wax emulsion, 3 parts wetting agent, and 0.5 parts preservative. The preparation method of the aqueous prepolymer includes the following steps: S1: Acrylamide and methylstyrene in a weight ratio of 1:0.1 are added to a solvent (water and ethanol in a volume ratio of 1:1), followed by the addition of an initiator accounting for 1 wt% of acrylamide, and the reaction is carried out at 60°C for 5 h. S2: Filter and remove the solvent by rotary evaporation to obtain the aqueous prepolymer.

[0043] The preparation method of the scratch-resistant agent is as follows: Aminated silica was placed in a solution of 15 wt% 1,6-hexanediol diglycidyl ether and stirred at 40°C for 3 hours. The mixture was then filtered, washed, and dried to obtain the final product.

[0044] Example 3 This embodiment relates to an environmentally friendly ink for cigarette label paper, comprising, by weight: 58 parts acrylic emulsion, 17 parts polyurethane emulsion, 28 parts waterborne prepolymer, 90 parts solvent, 90 parts waterborne pigment, 2.8 parts di(methacryloyloxyethyl) hydrogen phosphate, 6 parts scratch resistant agent, 1 part initiator, 3 parts defoamer, 3 parts stabilizer, 3 parts leveling agent, 1.5 parts wax emulsion, 2.5 parts wetting agent, and 0.3 parts preservative. The preparation method of the aqueous prepolymer includes the following steps: S1: Acrylamide and styrene in a weight ratio of 1:0.15 were added to a solvent (water and ethanol in a volume ratio of 1:1), followed by the addition of an initiator accounting for 1 wt% of acrylamide, and the reaction was carried out at 65°C for 5 h. S2: Filter and remove the solvent by rotary evaporation to obtain the aqueous prepolymer.

[0045] The preparation method of the scratch-resistant agent is as follows: Aminated silica was placed in a solution of 10 wt% diepoxy monomer and stirred at 45 °C for 3 h. The mixture was then filtered, washed, and dried to obtain the product. The diepoxy monomer was selected from diepoxyglycerol ether and 1,4-butanediol diglycidyl ether in a weight ratio of 1:2.

[0046] Example 4 The difference between this embodiment and Embodiment 3 is that 4-vinylbiphenyltriazole is used instead of styrene. The preparation method of 4-vinylbiphenyltriazole is as follows: 5-Bromo-1H-benzotriazole and 4-vinylphenylboronic acid in a molar ratio of 1:1 were added to a solvent (1,4-dioxane and water in a volume ratio of 5:1). Potassium carbonate and tetra-triphenylphosphine palladium were then added. The mixture was refluxed at 100°C under nitrogen atmosphere for 10 h. Water was removed by anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The mixture was purified by silica gel column chromatography (DCM:PE = 1:10) to obtain the product. The amount of potassium carbonate added was 80 wt% of the mass of 5-bromo-1H-benzotriazole, and the amount of tetra-triphenylphosphine palladium added was 30 wt% of the mass of 5-bromo-1H-benzotriazole.

[0047] Example 5 The difference between this embodiment and Embodiment 3 is that the weight ratio of acrylamide to styrene is 1:0.3.

[0048] Example 6 The difference between this embodiment and Example 3 is that the solution concentration of the diepoxy monomer is 3wt%.

[0049] Example 7 The difference between this embodiment and Embodiment 3 is that the diepoxy monomer is diepoxyglycerol ether.

[0050] Example 8 The difference between this embodiment and Embodiment 3 is that the diepoxy monomer is selected from diepoxyglycerol ether and 1,4-butanediol diglycidyl ether in a weight ratio of 2:1.

[0051] Example 9 The difference between this embodiment and Embodiment 3 is that the scratch-resistant agent is aminated silicon dioxide.

[0052] Comparative Example 1 The difference between this comparative example and Example 3 is that N,N-methylenebisacrylamide is used instead of di(methacryloyloxyethyl) hydrogen phosphate.

[0053] Comparative Example 2 The difference between this comparative example and Example 3 is that styrene is not added in the preparation of the aqueous prepolymer.

[0054] Comparative Example 3 The difference between this comparative example and Example 3 is that an equal amount of polyurethane emulsion is used to replace the waterborne prepolymer.

[0055] Comparative Example 4 The difference between this comparative example and Example 3 is that the amount of waterborne prepolymer added is 40 parts.

[0056] Test Example 1 The environmentally friendly inks prepared in the above embodiments and comparative examples were subjected to performance tests, and the test results are shown in Table 1. Viscosity was determined according to GB / T13217.4-2008, the test method for viscosity of liquid inks. For precipitation testing: 100g of the environmentally friendly ink sample was placed in a bottle and left at room temperature for 7 days or at 60℃ for 12 hours. The precipitation was observed. Grade 1 indicated no visible precipitation or stratification; Grade 2 indicated a basically uniform system with a slight thin layer of precipitation at the bottom, which could be quickly and evenly dispersed after shaking; Grade 3 indicated obvious stratification with a thick layer of precipitation at the bottom, which was still difficult to disperse after shaking.

[0057]

[0058] Test Example 2 The environmentally friendly inks prepared in the above examples and comparative examples were mixed evenly and printed onto cigarette label paper using a printhead at a speed of 150 m / min. The ink was then cured at 70°C for 10 seconds to obtain the printed ink layer. The smoothness of inkjet printing was recorded, and the adhesion, color difference, and scratch resistance of the printed ink layer were tested. The test results are shown in Table 2. Adhesion: determined according to GB / T13217.7-2009 Test Method for Adhesion of Liquid Ink; Color difference: the L, a, and b values ​​of the sample at room temperature were measured using a Colori7 desktop spectrophotometer, and the color difference ΔE was calculated using the CIE1976Lab color difference formula. A smaller color difference ΔE indicates a more uniform dispersion of the anti-counterfeiting color-changing ink components and better color uniformity; Scratch resistance: five metal finger-shaped scratching heads with a diameter of 5 mm were used to scratch the ink layer surface under a 10 N load, forming scratches. After the test, the scratches were observed visually under sufficient light to compare their visibility. Level 1: Scratches are almost invisible or completely invisible; Level 2: Scratches are basically visible; Level 3: Scratches are clearly visible, and the surface shows changes in gloss or abrasion.

[0059] Table 2

[0060] Based on the above results, the environmentally friendly ink prepared in this application has good adhesion, storage stability and scratch resistance, which can meet the usage requirements of cigarette packaging paper.

[0061] Based on the comparison between Example 4 and Example 3, the waterborne prepolymer obtained by using nitrogen heterocyclic compounds and acrylamide has high storage stability and adhesion of environmentally friendly inks, and high color uniformity and scratch resistance of the ink layer, which can meet the usage requirements of cigarette packaging paper.

[0062] A comparison of Examples 5 and 3 shows that the waterborne prepolymer contains a large proportion of compounds with benzene rings and double bonds, which affects the compatibility of the waterborne prepolymer matrix in the overall ink, thereby reducing the ink's adhesion and color uniformity, and slightly affecting storage stability. The reason for this is that the increased proportion of this compound reduces the proportion of acrylamide, thus affecting the role of acrylamide as a scratch-resistant agent, thereby reducing storage stability to some extent.

[0063] A comparison of Examples 6 and 3 shows that reducing the solution concentration of the diepoxy monomer in the preparation of the scratch-resistant agent reduces the number of epoxy groups on the silica surface, thereby affecting the storage stability of the scratch-resistant agent in the ink and the adhesion of the ink, and also reducing the color uniformity of the ink.

[0064] A comparison of Examples 7, 8 and 3 shows that changes in the type of bisepoxy monomers can slightly affect the adhesion of the ink, but mainly affect the storage stability and scratch resistance of the ink.

[0065] The comparison between Example 9 and Example 3 shows that the storage stability of non-epoxidized silica in ink is significantly worse, the overall ink viscosity decreases and the color difference increases. This proves that epoxidized silica interacts with water-based prepolymers and di(methacryloyloxyethyl) hydrogen phosphate, which facilitates the stable storage of scratch-resistant agents.

[0066] The comparison between Comparative Example 1 and Example 3 shows that di(methacryloyloxyethyl) hydrogen phosphate not only acts as a crosslinking agent, but also affects the storage stability, adhesion, color difference and scratch resistance of the ink. It can work well with water-based prepolymers.

[0067] The comparison between Comparative Example 2 and Example 3 shows that the absence of styrene in the water-based prepolymer mainly affects the color difference and scratch resistance of the ink layer, proving that the introduction of benzene rings in the water-based prepolymer increases the hardness of the ink, thereby improving the scratch resistance of the ink layer.

[0068] The comparison between Comparative Example 3 and Example 3 shows that the absence of water-based prepolymer significantly reduces the adhesion and scratch resistance of the ink layer.

[0069] The comparison between Comparative Example 4 and Example 3 shows that excessive addition of water-based prepolymer will lead to increased ink viscosity, resulting in nozzle clogging during printing. Furthermore, the increased viscosity will cause greater color difference in the ink layer. Therefore, the amount of water-based prepolymer added should not be excessive.

[0070] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. An environmentally friendly ink for cigarette label paper, characterized in that, By weight, including: Acrylic emulsion 55-60 parts, polyurethane emulsion 15-20 parts, waterborne prepolymer 25-30 parts, solvent 80-100 parts, waterborne pigment 80-100 parts, di(methacryloyloxyethyl) hydrogen phosphate 2.5-3 parts, scratch resistant agent 4-8 parts, initiator 1-1.5 parts, defoamer 2-4 parts, stabilizer 2-4 parts, leveling agent 2-4 parts, wax emulsion 1-2 parts, wetting agent 2-3 parts, preservative 0.1-0.5 parts; The aqueous prepolymer is obtained by polymerizing acrylamide and a compound with benzene rings and double bonds, and the scratch-resistant agent is modified silica.

2. The environmentally friendly ink for cigarette label paper according to claim 1, characterized in that, The weight ratio of the aqueous prepolymer to the di(methacryloyloxyethyl) hydrogen phosphate is 10:

1.

3. The environmentally friendly ink for cigarette label paper according to claim 2, characterized in that, The weight ratio of the acrylamide to the compound with benzene rings and double bonds is 1:(0.1-0.2).

4. The environmentally friendly ink for cigarette label paper according to claim 3, characterized in that, The compound containing a benzene ring and a double bond includes at least one of styrene, methylstyrene, and 4-vinylbiphenyltriazole; the structural formula of the 4-vinylbiphenyltriazole is: 。 5. The environmentally friendly ink for cigarette label paper according to any one of claims 1-4, characterized in that, The method for preparing the aqueous prepolymer includes the following steps: S1: Acrylamide and compounds with benzene rings and double bonds in a weight ratio of 1:(0.1-0.2) are added to a solvent, followed by the addition of an initiator, and the reaction is carried out at 60-70℃ for 4-5 hours. S2: Filter and remove the solvent to obtain the aqueous prepolymer.

6. The environmentally friendly ink for cigarette label paper according to any one of claims 1-4, characterized in that, The scratch-resistant agent is silicon dioxide obtained by surface modification of epoxy monomers.

7. The environmentally friendly ink for cigarette label paper according to claim 6, characterized in that, The method for preparing the scratch-resistant agent is as follows: Aminated silica is placed in a solution of 5-15 wt% diepoxy monomer and stirred at 40-50°C for 2-3 hours. The mixture is then filtered, washed, and dried to obtain the final product.

8. The environmentally friendly ink for cigarette label paper according to claim 7, characterized in that, The diepoxy monomer includes at least one of diepoxyglycerol ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, and 1,6-hexanediol diglycidyl ether.

9. The environmentally friendly ink for cigarette label paper according to claim 8, characterized in that, The diepoxy monomer is selected from diepoxyglycerol ether and 1,4-butanediol diglycidyl ether in a weight ratio of 1:

2.

10. A printing process using environmentally friendly inks for cigarette label paper as described in any one of claims 1-9, characterized in that, The acrylic emulsion, polyurethane emulsion, water-based prepolymer, solvent, water-based pigment, di(methacryloyloxyethyl) hydrogen phosphate, scratch-resistant agent, defoamer, stabilizer, leveling agent, wax emulsion, wetting agent, and preservative are mixed to obtain printing ink. The printing ink is printed on cigarette label paper and then cured at 60-70℃ for 10-15 seconds to obtain the final product.

Images