Ink formula and process for improving the stability of gravure proofing production

Abstract

This application provides an ink formulation and process for improving the stability of gravure proofing production, relating to the field of printing technology. The ink formulation provided in this application includes 60-70% binder, 10-18% pigment, 0.5-1% defoamer, 1.5-3% filler, 1-3% alcohol solvent, and water as the balance. The filler is silane coupling agent-modified calcium carbonate; the binder is an aqueous acrylic emulsion or polyurethane emulsion with a mass ratio of (30-85):(15-70). This polyurethane emulsion is prepared by reacting aliphatic diisocyanate and L-lysine diisocyanate with a polyol, and a 3-methoxy-4-hydroxymandelic acid chain extender is introduced. Using this ink formulation for printing avoids the low production efficiency and increased production costs caused by repetitive labor, achieving stable gravure printing production. The printed products have uniform and stable color, high adhesion, and good durability.

Description

Technical Field

[0001] This application relates to the field of printing technology, and in particular to an ink formulation and process for improving the stability of gravure proofing production. Background Technology

[0002] Gravure printing, or gravure printing for short, is a printing technique that uses an engraved plate to press ink onto a substrate, creating a three-dimensional pattern. It is widely used in packaging, labeling, currency, and securities printing. Ink is one of the key raw materials in gravure printing, and its quality directly affects the printing quality and production efficiency. Traditional gravure inks are solvent-based, containing large amounts of benzene and ester solvents, which inevitably evaporate into the air during printing and drying, impacting the environment and harming the health of operators. With increasingly stringent national regulations on VOC content in inks, the use of solvent-based inks is decreasing, while water-based inks, which significantly reduce VOC emissions, are now used in numerous fields.

[0003] Current water-based inks all suffer from uneven coloring, poor production stability, and poor print quality during printing, which is related to their composition. For example, the binders in water-based inks are usually resin materials, such as acrylic resins, but they generally have poor adhesion, requiring the addition of large amounts of ethanol to improve them. However, this may cause the ink to demulsify or thicken, affecting printing stability and product quality. Furthermore, during long-term storage, the compatibility between pigments, fillers, and binders in water-based inks deteriorates, leading to clumping and sedimentation, resulting in a decline in print quality. In addition, printing process conditions also affect printing stability.

[0004] Current research on the printing stability of water-based gravure inks mainly focuses on improving the storage stability of the inks. For example, patent CN120137445A discloses a gravure printing ink composition and gravure printing method, using pentaerythritol as a matrix, esterifying it through an acylation reaction to obtain a pentaerythritol ester containing brominated isobutyl group, and then polymerizing it with tert-butyl acrylate through an atom transfer radical polymerization reaction to form a branched acrylate prepolymer, which is added to the ink composition as a crosslinking agent. Polydopamine nanoparticles are also introduced as a light absorber, thereby improving the ink's adhesion and thermal cycling stability. Therefore, there is currently a lack of systematic research and overall solutions to improve printing stability, and the common industry problems of uneven coloring, poor stability, and difficulty in controlling printing quality in existing water-based gravure ink production cannot be fundamentally solved.

[0005] Therefore, it is necessary to provide a systematic gravure printing ink formulation and process to improve the stability of gravure proofing production. Summary of the Invention

[0006] The purpose of this application is to address the shortcomings of existing technologies by providing an ink formula and process that improves the stability of gravure printing proofing production. Printing using the ink formula of this application avoids the low production efficiency and increased production costs caused by repetitive labor. In addition, the use of a pneumatic stirring device ensures long-term storage stability, thereby achieving stable gravure printing production. The printed products have uniform and stable colors, high adhesion, and good durability.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows: On the one hand, an ink formulation for improving the stability of gravure proofing production is provided, comprising the following components by weight percentage: 60-70% binder, 10-18% pigment, 0.5-1% defoamer, 1.5-3% filler, 1-3% alcohol solvent, and water as the balance; wherein, The filler is calcium carbonate modified with silane coupling agent; The binder is an aqueous acrylic emulsion or a polyurethane emulsion with a mass ratio of (30-85):(15-70); the preparation method of the polyurethane emulsion includes the following steps: The polyol is dehydrated, and then diisocyanate and catalyst are added to react. Then, a first chain extender and a second chain extender are added sequentially to react and obtain a polyurethane prepolymer. Finally, a neutralizing agent is added for neutralization, and water is added for shear emulsification to obtain a polyurethane emulsion. The first chain extender is 2,2-dimethylolpropionic acid and 3-methoxy-4-hydroxymandelic acid in a mass ratio of (65-90):(10-35). The second chain extender is a tertiary amine alcohol. The diisocyanate contains aliphatic diisocyanate and L-lysine diisocyanate in a mass ratio of (70-80):(20-30).

[0008] This application uses water-based acrylic emulsion and polyurethane emulsion as binders to prepare water-based inks, which overcomes the defects of poor water resistance and poor adhesion of water-based inks prepared with water-based acrylic emulsion as binder. The ink adhesion is improved, and the compatibility between the binder and pigment in the water-based ink is improved, achieving uniform coloring in the printing process, improving the stability of printing production, and making it suitable for printing on a variety of substrates.

[0009] Furthermore, the aqueous acrylic emulsion has a solid content of 30-50% and a hydroxyl content of 5.0-9.5%. This aqueous acrylic emulsion is commercially available or can be prepared using methods well-known to those skilled in the art.

[0010] Furthermore, the method for preparing the polyurethane emulsion includes the following steps: The polyol is dehydrated, mixed with diisocyanate and catalyst, and reacted at 60-65°C for 30-40 min. Then, the temperature is raised to 75-80°C and the reaction continues for 60-90 min. The first chain extender is added and the reaction continues for 90-120 min. Then, the second chain extender is added and the reaction continues for 60-90 min to obtain a polyurethane prepolymer. The temperature is lowered to 35-40°C, a neutralizing agent is added and the reaction continues for 30-40 min. Water is added under stirring and emulsification continues for 40-60 min to obtain a polyurethane emulsion.

[0011] Furthermore, the above-mentioned polyurethane emulsion preparation process has the following limitations: The polyol is a polyether polyol and / or a polyester polyol; wherein the polyester polyol is selected from any one or a combination of several of poly(1,4-butylene adipate), poly(butylene adipate), poly(hexylene adipate), and polycaprolactone diol; the polyether polyol is selected from any one or a combination of several of polytetrahydrofuran ether diol, polypropylene diether alcohol, and polyethylene diether alcohol; and / or The aliphatic diisocyanate is selected from hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and dicyclohexylmethane diisocyanate (HDI). 12 Any one or a combination of several of MDI, tetramethylphenyl dimethylene diisocyanate (TMXDI); and / or, The tertiary amino alcohol is selected from any one or a combination of several of triethanolamine, N-methyldiethanolamine, N-benzyl-N-methylethanolamine, and diethylaminoethanol; and / or, The catalyst is selected from organotin compounds, including but not limited to dibutyltin dilaurate, stannous octoate, etc. The neutralizing agent is triethylamine; and / or, The mass ratio of the polyol, diisocyanate, first chain extender, second chain extender, neutralizer, and catalyst is (30-35):(20-25):(3-3.8):(1-1.5):(3-4):(0.03-0.05); and / or, The solid content of the polyurethane emulsion is 35-40%.

[0012] Traditional polyurethane emulsions exhibit relatively poor water and solvent resistance, affecting their retort resistance and leading to decreased printing quality. The waterborne polyurethane of this application is prepared using aliphatic diisocyanate, L-lysine diisocyanate, and polyol, and incorporates 3-methoxy-4-hydroxymandelic acid. Compared to traditional waterborne polyurethanes, this waterborne polyurethane demonstrates improved water and solvent resistance, thereby enhancing the retort resistance of waterborne inks and improving ink adhesion to substrate surfaces. Furthermore, this waterborne polyurethane also contributes to improving the quality of the ink film after formation, giving it good abrasion resistance and improved storage stability.

[0013] Furthermore, the defoamer is selected from any one or a combination of mineral oil defoamers, silicone defoamers, and polyether defoamers.

[0014] Furthermore, the pigment is any of the inorganic or organic pigments known to those skilled in the art.

[0015] Furthermore, the alcohol solvent is any one of ethanol, isopropanol, propylene glycol, and propylene glycol butyl ether.

[0016] Furthermore, the filler is silane coupling agent modified calcium carbonate, and its preparation method includes the following steps: Calcium carbonate is dispersed in sufficient anhydrous ethanol, a silane coupling agent is added, and the mixture is reacted at 75–85°C for 5–6 hours. After filtration, drying, and pulverization, the product is obtained.

[0017] Furthermore, in the above-mentioned preparation process of calcium carbonate modified with silane coupling agent, the particle size of calcium carbonate is 20–60 nm; and / or, The mass ratio of calcium carbonate to silane coupling agent is 10:(0.2–0.3); and / or, The silane coupling agent is any one or a combination of several of epoxy silane coupling agents, amino silane coupling agents, and vinyl silane coupling agents; wherein, epoxy silane coupling agents include, but are not limited to, γ-glycidoxypropyltrimethoxysilane (KH-560), γ-glycidoxypropyltriethoxysilane (KH-561), and diglycidoxypropyldimethoxysilane; amino silane coupling agents include, but are not limited to, γ-aminopropyltriethoxysilane (KH-550), aminopropyltrimethoxysilane (APTMS), N-β-aminoethyl-γ-aminopropyldimethoxysilane (KH-602), and N-β-aminoethyl-γ-aminopropyltrimethoxysilane (KH-792); and vinyl silane coupling agents include, but are not limited to, vinyltrimethoxysilane (KH-570), vinyltriethoxysilane, and vinyltris(2-methoxyethoxy)silane.

[0018] The main function of fillers in inks is to increase the thickness and volume of the paint film, improve the fluidity of the coating, and enhance the ink's hiding power and abrasion resistance. Calcium carbonate is inexpensive and has good hiding power, making it a commonly used filler in water-based inks. However, calcium carbonate has high oil and water absorption and a strong tendency to self-aggregate in inks, leading to decreased water resistance, uneven and unstable color in printed products, and potentially a decline in the physical properties of the film. This application modifies calcium carbonate with a silane coupling agent, improving its hydrophobicity. The modified calcium carbonate can couple with the binders and some organic pigments in the ink, improving the compatibility between calcium carbonate and ink and avoiding color instability problems during the printing process.

[0019] In a further embodiment, the applicant discovered that calcium carbonate modified with chitosan and silane coupling agents not only does not affect the stability of its printing color, but also helps to further improve the abrasion resistance of the ink film. In particular, calcium carbonate modified with vinyl silane coupling agents exhibits even better performance after further modification, and also improves the storage stability and durability of the ink. The chitosan used is modified with 2-octenyl succinic anhydride and phenyl succinic anhydride.

[0020] A method for further modifying calcium carbonate with chitosan and silane coupling agents includes the following steps: (1) Chitosan was dispersed in an organic solvent and stirred for 8-12 hours. 2-Octenylsuccinic anhydride and phenylsuccinic anhydride were added, and the temperature was raised to 110-120℃ and reacted for 6-8 hours. After the reaction was completed, the mixture was placed in an ice-water bath for rapid sedimentation and post-treatment to obtain anhydride-modified chitosan. (2) Disperse the silane coupling agent modified calcium carbonate in an ethanol aqueous solution, add the acid anhydride modified chitosan, and react at 75-85℃ for 2-3 hours to obtain chitosan-silane coupling agent modified calcium carbonate. After the reaction is completed, cool and then perform post-treatment to obtain the final product.

[0021] In the above modification step (1), the chitosan has a molecular weight of 50–100 kDa and a degree of deacetylation of 90–95%; and / or, The anhydride is 2-octenylsuccinic anhydride and phenylsuccinic anhydride in a mass ratio of (45-65):(35-55), and the mass ratio of the anhydride to chitosan is (2.5-3.7):10; and / or, The organic solvent is dimethylformamide (DMF), but it can also be replaced with other organic solvents known to those skilled in the art that can satisfy the above reaction.

[0022] In the above modification step (2), the ethanol aqueous solution is prepared by mixing ethanol and water in a volume ratio of (60-80):(20-40); The mass ratio of silane coupling agent modified calcium carbonate to acid anhydride modified chitosan is 10:(0.5~1).

[0023] In the above modification process, post-processing includes, but is not limited to, steps well known to those skilled in the art such as vacuum filtration / filtration, washing, drying, and pulverization.

[0024] Furthermore, the pH of the aforementioned water-based ink is 8.0–8.5, and the viscosity is 16.0–24.8 s (23°C, Zahn cup No. 2). To control the pH of the water-based ink within the specified range, pH adjusters well known to those skilled in the art can be added.

[0025] On the other hand, this application also provides a process for improving the stability of gravure printing proofing production, including the following steps: S1. According to the formula, mix the binder with water and alcohol solvent, stir at low speed for 30-40 minutes, then add pigment and filler and stir at medium speed for 20-30 minutes, grind, finally add defoamer and stir evenly, filter to obtain water-based ink, and place it in a pneumatic stirring device for later use. S2. Using the water-based ink obtained in step S1, print using a gravure printing machine. The drying section is divided into three temperature control sections: the first section temperature is 50-55℃, the second section temperature is 70-75℃, and the third section temperature is 30-35℃.

[0026] This application achieves stable coloring in printing by optimizing the water-based ink formulation and combining it with the aforementioned printing process, resulting in uniform color and high-quality ink film. Specifically, the printing process employs a three-stage drying process with controlled temperature ranges, ensuring the drying of both the surface and deeper ink layers while preventing issues such as air bubbles and stickiness later on, thus improving coloring stability and product quality.

[0027] Further, in step S1 above, the low-speed stirring speed is 150–200 r / min; the medium-speed stirring speed is 400–500 r / min; and / or, During the grinding process, the grinding machine speed is 2500-2800 r / min, and grinding is carried out until the water-based ink has the specified fineness.

[0028] Furthermore, during the printing process, apart from the process adjustment in the drying section, other conventional parameters such as the line count of the anilox roller, printing pressure, and printing speed can all be adjusted according to conventional methods.

[0029] Furthermore, the pneumatic stirring device includes: an insulated container body, a cover, a pneumatic motor, and a stirring device; the cover is a detachable sealing cover with a pre-drilled hole for a stirring shaft in the center; the pneumatic motor is fixedly installed above the center of the cover body; the stirring device is disposed inside the insulated container body, and the stirring device includes a stirring shaft and a stirring blade fixedly installed at the bottom of the stirring shaft, the stirring shaft passing through the stirring shaft hole in the center of the cover body and connecting to the output shaft of the pneumatic motor.

[0030] Furthermore, the top of the insulated bucket is provided with several buckles at intervals to secure the lid, ensuring a seal while facilitating disassembly and cleaning.

[0031] Furthermore, the stirring blades are arranged in multiple layers, with horizontal spacing between the multiple layers of stirring blades. The bottommost stirring blade is close to the bottom of the insulated tank and has a safe gap to avoid contact with the bottom of the tank and causing scratches.

[0032] It includes an upper horizontal blade and a bottom scraper blade, the shape of which matches the bottom contour of the insulated barrel body 1.

[0033] Furthermore, the bottom of the side wall of the insulated barrel is provided with a discharge port, and the discharge port is equipped with a valve to control the flow of water-based ink.

[0034] Furthermore, both the insulated barrel body and the lid are designed with a double-layer structure, with the inner layer being made of stainless steel and the outer layer being an insulation layer.

[0035] Furthermore, multiple baffles are spaced apart on the side wall of the insulated barrel. Each baffle is a V-shaped column structure. The outer edges of the baffles are all in contact with the inner wall of the insulated barrel and extend from the top to the bottom of the inner wall of the insulated barrel, taking care to avoid the discharge port.

[0036] The pneumatic stirring device of this application adopts a structure of stirring blades + side wall baffles, which can effectively eliminate the stirring dead zone, avoid the sedimentation and agglomeration of pigments, fillers, etc. during long-term storage, significantly improve the dispersion uniformity, and improve the printing stability.

[0037] Furthermore, the bottom and side walls of the insulated container have a smooth transition, which reduces the flow resistance of water-based inks during stirring and avoids ink accumulation due to vertical interfaces.

[0038] Before operation, add the water-based ink to the insulated container, close the lid, and fasten the buckle to maintain a seal. During operation, turn on the pneumatic motor, which drives the coupling to transmit torque to the stirring shaft. The stirring shaft then drives the stirring blades to agitate the liquid, achieving pneumatic stirring. To discharge, open the outlet valve to release the water-based ink.

[0039] Compared with the prior art, this application has the following beneficial effects: 1. This application uses water-based acrylic emulsion and polyurethane emulsion as binders to prepare water-based inks, which overcomes the defects of poor water resistance and poor adhesion of water-based inks prepared with water-based acrylic emulsion as binder. The ink adhesion is improved, and the compatibility between the binder and pigment in the water-based ink is improved, achieving uniform coloring in the printing process. The printed products have uniform and stable colors and are suitable for printing on various substrates. At the same time, it also has good stability and film-forming properties.

[0040] 2. Compared with traditional waterborne polyurethane, the waterborne polyurethane of this application introduces a certain amount of 3-methoxy-4-hydroxymandelic acid, L-lysine diisocyanate and polyol into the hard segment, which improves the water resistance and solvent resistance, and the ink has high adhesion to the substrate surface, thus improving the film-forming performance of the ink on the substrate surface.

[0041] 3. The addition of silane coupling agent to the water-based ink of this application modifies calcium carbonate, which can couple with the binder and some organic pigments in the ink, improving the compatibility between calcium carbonate and ink and avoiding the problem of color instability during the printing process.

[0042] 4. The water-based ink of this application is placed in a pneumatic stirring device with a multi-layered stirring blade and sidewall baffle structure, which can effectively eliminate stirring dead zones, avoid pigment sedimentation and agglomeration during placement, significantly improve ink dispersion uniformity, further enhance printing and storage stability, and improve printing quality. Furthermore, the pneumatic stirring device has good sealing performance, which can prevent solvent evaporation.

[0043] 5. The water-based ink formula of this application is combined with the gravure printing process parameters to achieve color stability during the printing process, avoid low production efficiency and increased production costs caused by repetitive labor, achieve stable gravure printing production, and produce products with uniform and stable color, high adhesion and good durability. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the overall structure of the pneumatic stirring device of this application; Figure 2 This is a top view of the interior of the insulated barrel in this application.

[0045] The components in the diagram are marked as follows: 1-Insulated barrel, 11-Break plate, 2-Lid, 3-Pneumatic motor, 4-Stirring device, 41-Stirring shaft, 42-Stirring blade, 5-Discharge port, 6-Snap fastener. Detailed Implementation

[0046] To more clearly illustrate the overall concept of this application, a detailed description is provided below with reference to the accompanying drawings and embodiments. Numerous specific details are set forth in the following description to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described to avoid confusion with the invention.

[0047] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers. Preparation methods that do not specify specific methods are generally prepared using equipment or conventional methods well known in the art.

[0048] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0049] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0050] Unless otherwise specified, reagents or instruments used in the following embodiments, unless otherwise indicated by the manufacturer, are all commercially available products. Among them, aqueous acrylic emulsion (Joncyl) @ FLX 617-A was purchased from BSF, the defoamer was BSF's SF-808 defoamer, and the pigment was Aladdin's malachite green.

[0051] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0052] like Figure 1 , 2 The pneumatic stirring device shown includes: an insulated barrel 1, a cover 2, a pneumatic motor 3, and a stirring device 4; the cover 2 is a detachable sealing cover with a pre-drilled hole for the stirring shaft in the center; the pneumatic motor 3 is fixedly installed above the center of the cover 2, and the stirring device 4 is located inside the insulated barrel 1, including a stirring shaft 41 and a stirring blade 42 fixedly installed at the bottom of the stirring shaft 41. The stirring shaft 41 passes through the stirring shaft hole in the center of the cover and is connected to the output shaft of the pneumatic motor 3.

[0053] Furthermore, the top of the insulated bucket body 1 is provided with several buckles 6 at intervals to secure the lid, ensuring a seal while facilitating disassembly and cleaning. Furthermore, the bottom of the side wall of the insulated barrel 1 is provided with a discharge port 5, and the discharge port 5 is equipped with a valve to control the flow of water-based ink.

[0054] Furthermore, both the insulated container body 1 and the lid body 2 are designed with a double-layer structure, with the inner layer being made of stainless steel and the outer layer being an insulation layer.

[0055] Furthermore, multiple baffles 11 are spaced apart on the side wall of the insulated barrel 1. Each baffle 11 is a column structure with a V-shaped cross-section. The outer edges of the baffles 11 are all in contact with the inner wall of the insulated barrel 1 and extend from the top to the bottom of the inner wall of the insulated barrel 1, taking care to avoid the discharge port.

[0056] Furthermore, the stirring blades 42 are arranged in multiple layers, with the multiple layers of stirring blades arranged horizontally at intervals. The bottommost stirring blade is close to the bottom of the insulated tank and has a safe gap to avoid contact with the bottom of the tank and causing scratches.

[0057] The pneumatic stirring device of this application adopts a multi-layer stirring blade + side wall baffle structure, which can effectively eliminate the stirring dead zone, avoid the sedimentation and agglomeration of pigments, fillers, etc. during long-term storage, significantly improve the dispersion uniformity, and improve the printing stability.

[0058] Furthermore, the bottom and sidewalls of the insulated container 1 have a smooth transition, which reduces the flow resistance of water-based ink during stirring and avoids ink accumulation due to vertical interfaces.

[0059] Before operation, add the water-based ink to the insulated container 1, cover it with the lid 2, and fasten the buckle to maintain a seal. During operation, turn on the pneumatic motor 3, which drives the coupling to transmit torque to the stirring shaft 41. The stirring shaft 41 drives the stirring blades 42 to stir the liquid, achieving pneumatic stirring. When discharging, open the valve at the discharge port 5 to discharge the water-based ink.

[0060] The present application will be further described below by way of specific embodiments.

[0061] Example 1 An ink formulation for improving the stability of gravure printing proofing production is characterized by comprising the following components by weight percentage: 60% binder, 10% pigment, 0.5% defoamer, 1.5% filler, 1% isopropanol, and water as the balance; the binder is a water-based acrylic emulsion or polyurethane emulsion with a mass ratio of 30:70.

[0062] The preparation method of the above ink formulation includes the following steps: (1) Remove water from 30 parts by weight of polybutylene adipate diol, add 20 parts by weight of HDI and L-lysine diisocyanate in a mass ratio of 70:30, and 0.03 parts by weight of dibutyltin dilaurate, react at 60°C for 30 min, then raise the temperature to 75°C and continue the reaction for 60 min, then add 3 parts by weight of 2,2-dimethylolpropionic acid and 3-methoxy-4-hydroxymandelic acid in a mass ratio of 65:35, continue the reaction at 75°C for 90 min, then add 1 part by weight of triethanolamine and continue the reaction for 60 min to obtain polyurethane prepolymer; cool down to 35°C, add 3 parts by weight of triethylamine and react for 30 min, then add water under stirring and emulsify for 40 min to obtain polyurethane emulsion with a solid content of 40%.

[0063] (2) Disperse 10 parts by weight of calcium carbonate (particle size 20 nm) in sufficient anhydrous ethanol, add 0.2 parts by weight of KH-560, react at 75°C for 5 h, filter, dry and pulverize to obtain the filler.

[0064] (3) Mix the binder with water and isopropanol, stir at 150 r / min for 30 min, then add pigment and filler, stir at 400 r / min for 20 min, grind at 2500 r / min, finally add defoamer and stir evenly, filter to obtain water-based ink; place in a pneumatic stirring device for later use.

[0065] Example 2 An ink formulation for improving the stability of gravure printing proofing production is characterized by comprising the following components by weight percentage: 70% binder, 18% pigment, 1% defoamer, 1.5% filler, 3% isopropanol, and water as the balance; the binder is an aqueous acrylic emulsion or polyurethane emulsion with a mass ratio of 85:15.

[0066] The preparation method of the above ink formulation includes the following steps: (1) Remove water from 35 parts by weight of polytetrahydrofuran ether diol, add 25 parts by weight of IPDI and L-lysine diisocyanate in a mass ratio of 80:20, and 0.05 parts by weight of dibutyltin dilaurate. React at 65°C for 40 min, then raise the temperature to 80°C and continue the reaction for 90 min. Then add 3.8 parts by weight of 2,2-dimethylolpropionic acid and 3-methoxy-4-hydroxymandelic acid in a mass ratio of 90:10, and continue the reaction at 80°C for 120 min. Then add 1.5 parts by weight of N-methyldiethanolamine and continue the reaction for 90 min to obtain a polyurethane prepolymer. Cool down to 40°C, add 4 parts by weight of triethylamine and react for 40 min. Add water under stirring and emulsify for 60 min to obtain a polyurethane emulsion with a solid content of 35%.

[0067] (2) Disperse 10 parts by weight of calcium carbonate (particle size 60 nm) in sufficient anhydrous ethanol, add 0.3 parts by weight of KH-570, react at 85°C for 6 h, filter, dry and pulverize to obtain the filler.

[0068] (3) Mix the binder with water and isopropanol, stir at 200 r / min for 40 min, then add pigment and filler, stir at 500 r / min for 20 min, grind at 2800 r / min, finally add defoamer and stir evenly, filter to obtain water-based ink; place in a pneumatic stirring device for later use.

[0069] Example 3 The difference from Example 2 is that the preparation method of the filler includes the following steps: 10 parts by weight of calcium carbonate (particle size 60 nm) are dispersed in sufficient anhydrous ethanol, 0.3 parts by weight of KH-570 are added, the mixture is reacted at 85°C for 6 hours, filtered, dried, and pulverized to obtain silane coupling agent modified calcium carbonate; 1 part by weight of chitosan (molecular weight 50 kDa, degree of deacetylation 90%) is dispersed in sufficient DMF, stirred for 8 hours, and 0.25 parts by weight of 2-octenyl succinic anhydride and phenyl ether in a mass ratio of 45:55 are added. Succinic anhydride was stirred and dissolved, and the mixture was heated to 110℃ and reacted for 6 hours. After the reaction was complete, the mixture was placed in an ice-water bath for rapid sedimentation, filtered, washed, and dried to obtain anhydride-modified chitosan. 10 parts by weight of silane coupling agent-modified calcium carbonate was dispersed in sufficient ethanol-water solution (ethanol:water ratio 7:0:30), and 0.5 parts by weight of anhydride-modified chitosan was added. The mixture was reacted at 75℃ for 2 hours to obtain chitosan-silane coupling agent-modified calcium carbonate. After the reaction was completed, the mixture was cooled, filtered, washed, dried, and pulverized to obtain the filler material. It was then placed in a pneumatic stirring device for later use.

[0070] Example 4 The difference from Example 2 is that the preparation method of the filler includes the following steps: 10 parts by weight of calcium carbonate (particle size 60 nm) are dispersed in sufficient anhydrous ethanol, 0.3 parts by weight of KH-570 are added, the mixture is reacted at 85°C for 6 hours, filtered, dried, and pulverized to obtain silane coupling agent modified calcium carbonate; 1 part by weight of chitosan (molecular weight 100 kDa, degree of deacetylation 95%) is dispersed in sufficient DMF, stirred for 12 hours, and 0.37 parts by weight of 2-octene at a mass ratio of 64:35 are added. Succinic anhydride and phenyl succinic anhydride were stirred and dissolved, and the mixture was heated to 120°C and reacted for 8 hours. After the reaction was completed, the mixture was placed in an ice-water bath for rapid sedimentation, filtered, washed, and dried to obtain anhydride-modified chitosan. 10 parts by weight of silane coupling agent-modified calcium carbonate were dispersed in sufficient ethanol aqueous solution (ethanol:water ratio of 7:0:30), and 1 part by weight of anhydride-modified chitosan was added. The mixture was reacted at 85°C for 3 hours to obtain chitosan-silane coupling agent-modified calcium carbonate. After the reaction was completed, the mixture was cooled, filtered, washed, dried, and pulverized to obtain the filler.

[0071] Example 5 The difference from Example 3 is that KH-570 is replaced with an equal amount of KH-560.

[0072] Example 6 The difference from Example 3 is that the acid anhydride is only 2-octenylsuccinic anhydride, while the total amount of acid anhydride remains unchanged.

[0073] Example 7 The difference from Example 3 is that the acid anhydride is only phenylsuccinic anhydride, and the total amount of acid anhydride remains unchanged.

[0074] Example 8 The difference from Example 3 is that the anhydride-modified chitosan is replaced with unmodified chitosan, that is, chitosan is directly used to further modify the silane coupling agent-modified calcium carbonate to obtain the filler.

[0075] Comparative Example 1 The difference from Example 2 is that the binder is only an aqueous acrylic emulsion, and the total amount remains unchanged.

[0076] Comparative Example 2 The difference from Example 2 is that in the polyurethane emulsion preparation process, only IPDI diisocyanate is used, and the total amount remains unchanged.

[0077] Comparative Example 3 The difference from Example 2 is that, in the preparation of the polyurethane emulsion, the diisocyanate contains IPDI and L-lysine diisocyanate in a mass ratio of 1:1, and the total amount remains unchanged.

[0078] Comparative Example 4 The difference from Example 2 is that, in the preparation of the polyurethane emulsion, the first chain extender is only 2,2-dimethylolpropionic acid, and the total amount remains unchanged.

[0079] Comparative Example 5 The difference from Example 2 is that, in the preparation of the polyurethane emulsion, the first chain extender is 2,2-dimethylolpropionic acid and 3-methoxy-4-hydroxymandelic acid in a mass ratio of 6:4, and the total amount remains unchanged.

[0080] Comparative Example 6 The difference from Example 2 is that the polyurethane emulsion was replaced with Bayer's Bayhydrol U241 product.

[0081] Comparative Example 7 The difference from Example 2 is that the filler is unmodified calcium carbonate.

[0082] Test Example 1 The water-based inks obtained in the above embodiments and comparative examples were used to print on PE film substrates. The printing process parameters were: printing pressure 0.3 MPa, printing speed 150 m / min, and drying temperature: 50℃ in zone 1, 70℃ in zone 2, and 30℃ in zone 3. After the ink layer was fully cured, adhesion, boiling resistance, and abrasion resistance were tested. Adhesion was tested according to GB / T13217.7-2023. The boiling resistance was tested by immersing the printed material in water and boiling for 30 minutes. The film was then removed, the surface moisture was absorbed with absorbent paper, and the film was observed to see if it peeled off or turned white. The abrasion resistance was tested using a friction testing machine with a test load of 500 g ± 5 g and a friction speed of 30 times / min ± 2 times / min. The ink layer peeling rate was calculated after 200 friction cycles using the following formula: Ink layer peeling rate = (Ink layer mass before friction - Ink layer mass after friction) / Ink layer mass before friction × 100%.

[0083] The test results are shown in Table 1 below.

[0084] Table 1. Coloring properties, boiling resistance, and abrasion resistance of water-based inks

[0085] As shown in the table, the water-based ink provided in this application exhibits high adhesion, excellent resistance to boiling, and good abrasion resistance, with a low ink layer peeling rate after 200 cycles of abrasion. Compared to Example 2, Comparative Example 1 used only water-based acrylic emulsion as a binder, while Comparative Example 6 added commercially available polyurethane emulsion as a binder, resulting in a decrease in abrasion resistance, boiling resistance, and adhesion. This indicates that the addition of polyurethane emulsion in this application can improve the film-forming properties of the ink.

[0086] Test Example 2 Printed materials were prepared according to the method provided in Test Example 1. A CM-2600d spectrophotometer was used to test five test points on the same batch of printed materials, and the color difference value ΔE was calculated. The color difference values ​​of printed materials from different batches were also tested, with five batches selected for testing. In addition, a control group experiment was set up with the following printing process parameters: printing pressure 0.3 MPa, printing speed 150 m / min, and drying temperature 70℃.

[0087] The results are shown in Table 2 below.

[0088] Table 2. Printing color uniformity

[0089] As shown in the table, compared with the comparative example and the control group, the water-based ink provided in this application, combined with the printing process, exhibits excellent color stability during printing, uniform color of printed products, and high product quality.

[0090] Test Example 3 The water-based ink was placed in a standard sealed container and left for 6 months. The presence of sediment was observed, and the viscosity change was tested. If no sediment was observed and the viscosity change was small, the ink was considered to have a stable storage period of at least 6 months. Alternatively, the water-based ink obtained in Example 2 was placed in a conventional sealed container and a pneumatic stirring device and left at 60°C for 7 days. The presence of sediment and viscosity changes were observed.

[0091] The formula for calculating the viscosity change is as follows: Viscosity change = |Viscosity before centrifugal accelerated sedimentation test - Viscosity after centrifugal accelerated sedimentation test|.

[0092] The test results are shown in Table 3 below.

[0093] Table 3. Stability of water-based inks

[0094] As shown in the table, the water-based ink provided in this application exhibits a viscosity change of ≤1.5s after 6 months of storage, demonstrating excellent storage stability and a shelf life exceeding 6 months. Furthermore, the water-based ink obtained in Example 2 showed no precipitation after 7 days of storage in a conventional sealed container, with a viscosity change of approximately 2.5-2.8 (23°C, Zahn No. 2 cup). In contrast, the water-based ink placed in a pneumatic stirring device showed almost no viscosity change and no precipitation, further improving its stability.

[0095] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, this application is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope of this application should be within the protection scope of this application.

Claims

1. An ink formulation for improving the consistency of gravure proofing production, characterized in that, It comprises the following components by weight percentage: binder 60-70%, pigment 10-18%, defoamer 0.5-1%, filler 1.5-3%, alcohol solvent 1-3%, and water as the balance; wherein, The filler is calcium carbonate modified with silane coupling agent; The binder is an aqueous acrylic emulsion or a polyurethane emulsion with a mass ratio of (30-85):(15-70); the preparation method of the polyurethane emulsion includes the following steps: The polyol is dehydrated, and then diisocyanate and catalyst are added to react. Then, a first chain extender and a second chain extender are added sequentially to react and obtain a polyurethane prepolymer. Finally, a neutralizing agent is added for neutralization, and water is added for shear emulsification to obtain a polyurethane emulsion. The first chain extender is 2,2-dimethylolpropionic acid and 3-methoxy-4-hydroxymandelic acid in a mass ratio of (65-90):(10-35). The second chain extender is a tertiary amine alcohol. The diisocyanate contains aliphatic diisocyanate and L-lysine diisocyanate in a mass ratio of (70-80):(20-30).

2. The ink formulation for improving the production stability of gravure proofing according to claim 1, characterized by, The solid content of the waterborne acrylic emulsion is 30-50%, and the hydroxyl content is 5.0-9.5%.

3. The ink formulation for improving the production stability of gravure proofing according to claim 1, characterized by, The polyol is a polyether polyol and / or a polyester polyol; wherein the polyester polyol is selected from any one or a combination of several of poly(1,4-butylene adipate diol), poly(butylene adipate diol), poly(hexylene adipate diol), and polycaprolactone diol; and the polyether polyol is selected from any one or a combination of several of polytetrahydrofuran ether diol, polypropylene diether alcohol, and polyethylene diether alcohol.

4. The ink formulation for improving the production stability of gravure proofing according to claim 1, characterized by, The aliphatic diisocyanate is selected from any one or a combination of several of hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (H 12 MDI), tetramethylxylylene diisocyanate (TMXDI).

5. The ink formulation for improving the production stability of gravure proofing according to claim 1, characterized by, The tertiary amino alcohol is selected from any one or a combination of several of triethanolamine, N-methyldiethanolamine, N-benzyl-N-methylethanolamine, and diethylaminoethanol.

6. The ink formulation for improving the production stability of gravure proofing according to claim 1, wherein The preparation method of the silane coupling agent modified calcium carbonate includes the following steps: Calcium carbonate is dispersed in sufficient anhydrous ethanol, a silane coupling agent is added, and the mixture is reacted at 75–85°C for 5–8 hours. After filtration, drying, and pulverization, the product is obtained.

7. The ink formulation for improving the production stability of gravure proofing according to claim 6, characterized in that, The mass ratio of calcium carbonate to silane coupling agent is 10:(0.2-0.3).

8. The ink formulation for improving the production stability of gravure proofing according to claim 6, characterized by, The silane coupling agent is any one or a combination of several of the following: epoxy silane coupling agents, amino silane coupling agents, and vinyl silane coupling agents.

9. A process for improving the stability of gravure proofing production, characterized by, Includes the following steps: S1. The ink formulation for improving the stability of gravure printing proofing production according to any one of claims 1-8, wherein the binder is mixed with water and stirred at low speed for 30-40 minutes, then pigments and fillers are added and stirred at medium speed for 20-30 minutes, ground, and finally defoamer is added and stirred evenly, filtered, to obtain water-based ink; and placed in a pneumatic stirring device for later use. S2. Using the water-based ink obtained in step S1, print using a gravure printing machine. The drying section is divided into three temperature control sections: the first section temperature is 50-55℃, the second section temperature is 70-75℃, and the third section temperature is 30-35℃.

10. The process of claim 9, wherein, In step S1, the pneumatic stirring device includes: a heat-insulating barrel (1), a cover (2), a pneumatic motor (3), and a stirring device (4); the cover (2) is a detachable sealing cover with a pre-drilled stirring shaft hole in the center; the pneumatic motor (3) is fixedly installed above the center of the cover (2); the stirring device (4) is located inside the heat-insulating barrel (1), and the stirring device (4) includes a stirring shaft (41) and a stirring blade (42) fixedly installed at the bottom of the stirring shaft (41). The stirring shaft (41) passes through the stirring shaft hole in the center of the cover (2) and is connected to the output shaft of the pneumatic motor (3).

Images