A water-based varnish for inkjet printing and its manufacturing method

Abstract

This invention relates to the field of inkjet printing varnish technology, specifically disclosing a water-based varnish for inkjet printing and its manufacturing method. The manufacturing method of the water-based varnish is as follows: S1. Polyvinyl alcohol resin, hydroxypropyl cellulose, diethylamine, polyethylene glycol, and deionized water are stirred at 40-45°C for 15-20 minutes, and then polycarbodiimide emulsion is added and stirred for another 8-12 minutes to obtain a polyvinyl alcohol resin mixed emulsion; S2. Water-based acrylic resin, polyvinyl alcohol resin mixed emulsion, modified silica-alumina mixture, and deionized water are stirred and mixed to obtain a mixed liquid; S3. The mixed liquid is placed in a wet mill, and polydimethylsiloxane, sodium polyacrylate, sucrose fatty acid ester, and 2,5-tetrahydrofurandimethylethanol are added, followed by wet milling to obtain a grinding material; S4. The grinding material is filtered to obtain a water-based varnish with a viscosity of 10-15 mPa•s.

Description

Technical Field

[0001] This invention relates to the field of inkjet printing varnish technology, and in particular to a water-based inkjet printing varnish and its manufacturing method. Background Technology

[0002] With the rapid development of digital printing technology, inkjet printing has been widely used in packaging, advertising, publishing and other fields due to its flexibility, efficiency and wide applicability. In order to improve the gloss, three-dimensionality and other visual effects of printed materials, as well as their weather resistance such as abrasion resistance and water resistance, a layer of varnish needs to be sprayed after printing to improve the overall printing effect.

[0003] There are two main types of printing varnishes: water-based and oil-based. Water-based varnishes are made by mixing water as a solvent with water-based polymers such as acrylic resin and polyurethane resin, as well as additives such as leveling agents, defoamers, and thickeners. Water-based varnishes have low volatile organic compound (VOC) emissions and are relatively environmentally friendly. Oil-based varnishes, on the other hand, are made by mixing organic compounds such as toluene, xylene, and ethyl acetate with resins and additives. Oil-based varnishes are flammable and explosive, and some of the solvents used are toxic, which can easily cause environmental pollution.

[0004] Varnish is a consumable used for printing surface treatment. After forming a film, it increases the gloss, abrasion resistance, and water resistance of the printed surface, thus protecting the graphics on the substrate. With increasing environmental awareness, oil-based varnishes are now used less frequently, replaced by water-based varnishes. Water-based varnishes mainly use water as a solvent, resulting in less pollution, easier storage and transportation, lower cost, and wider availability of raw materials.

[0005] However, water-based varnishes currently on the market still have the following technical problems when used in inkjet printing: poor film-forming performance, resulting in varnish film layers with poor abrasion resistance, adhesion, water resistance and leveling properties, and unsatisfactory gloss.

[0006] Therefore, developing a water-based varnish with good gloss, good wear resistance, strong adhesion, and good water resistance is a technical problem that the inkjet printing varnish industry urgently needs to solve. Summary of the Invention

[0007] The purpose of this invention is to provide a water-based varnish for inkjet printing and a method for manufacturing the same, so as to solve the problems mentioned in the background art.

[0008] This invention provides a method for manufacturing water-based varnish for inkjet printing, comprising the following steps:

[0009] S1. Weigh 45-50 parts by weight of polyvinyl alcohol resin, 6-8 parts by weight of hydroxypropyl cellulose, 2-4 parts by weight of diethylamine, 1-3 parts by weight of polyethylene glycol, and 60-65 parts by weight of deionized water. Stir and mix at 40-45°C for 15-20 minutes. Then add 25-30 parts by weight of polycarbodiimide emulsion and continue stirring for 8-12 minutes to obtain a polyvinyl alcohol resin mixed emulsion.

[0010] S2. Place 40-45 parts by weight of waterborne acrylic resin, 30-38 parts by weight of polyvinyl alcohol resin mixed emulsion, 10-15 parts by weight of modified silica-alumina mixture, and 45-50 parts by weight of deionized water in a mixer with a speed of 600-800 rpm and stir for 30-40 minutes to obtain a mixed liquid.

[0011] S3. Place the mixture obtained in S2 into a wet mill, add 4-6 parts by weight of polydimethylsiloxane, 3-5 parts by weight of sodium polyacrylate, 1-3 parts by weight of sucrose fatty acid ester, and 0.5-0.8 parts by weight of 2,5-tetrahydrofurandimethylethanol, and then wet mill to obtain the grinding material.

[0012] S4. Filter the abrasive obtained in S3 to obtain a water-based varnish with a viscosity of 10-15 mPa•s.

[0013] As a preferred embodiment of the present invention, the polycarbodiimide emulsion is prepared by the following method:

[0014] Weigh 25-30 parts by weight of polycarbodiimide, 8-10 parts by weight of triethanolamine stearate, 7-8 parts by weight of polyhydroxyethyl methacrylate, 6-8 parts by weight of alkyl glycoside, 2-3 parts by weight of trifluoroethyl methacrylate, and 40-50 parts by weight of deionized water, and place them in an ultrasonic device for 25-30 minutes to obtain a polycarbodiimide emulsion.

[0015] As a preferred technical solution of the present invention, the modified silicon-aluminum mixture is prepared by the following method: 32-35 parts by weight of silicon dioxide and 15-20 parts by weight of α-alumina are weighed, mixed and treated in a plasma device for 3-5 minutes, and then placed in a reaction vessel with 5-7 parts by weight of γ-aminopropyltriethoxysilane, 3-5 parts by weight of sodium dodecylbenzenesulfonate, 2-4 parts by weight of polyvinylpyrrolidone and 70-80 parts by weight of deionized water to obtain the modified silicon-aluminum mixture.

[0016] As a preferred embodiment of the present invention, the wet grinding mill has a rotation speed of 3200-3500 rpm and a grinding time of 50-60 min.

[0017] As a preferred embodiment of the present invention, the media used in the wet grinding mill are steel balls with a particle size of 0.6 to 0.8 mm.

[0018] As a preferred embodiment of the present invention, the filter element used in the filtration process has a size of 2-5 μm and a filtration pressure of 0.1-0.2 MPa.

[0019] As a preferred embodiment of the present invention, the ultrasonic device has a frequency of 80-90Hz and a temperature of 40-50℃.

[0020] As a preferred embodiment of the present invention, the charge density of the plasma device is 1300–1400 C / cm³. 3 The gas flow rate is 1.2–1.5 L / min, the processing chamber pressure is 100–110 kPa, and the processing chamber temperature is 40–50 °C.

[0021] As a preferred embodiment of the present invention, the reaction temperature of the reactor is 90-95°C and the reaction time is 1.5-2.0h.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. In this invention, silica and α-alumina are mixed and treated in a plasma device. Then, γ-aminopropyltriethoxysilane, sodium dodecylbenzenesulfonate, and polyvinylpyrrolidone are added to obtain a modified silica-alumina mixture, which is then added to a water-based varnish. The high-energy particles such as electrons and ions generated by the plasma device can etch the surfaces of silica and α-alumina, introduce active functional groups such as hydroxyl and carboxyl groups, and increase the surface roughness of silica and α-alumina. The plasma treatment can provide more reaction sites for the subsequent grafting modification of the silane coupling agent γ-aminopropyltriethoxysilane, forming a denser cross-linked network. The high hardness of silica and the wear resistance of α-alumina combined can significantly improve the hardness and wear resistance of the water-based varnish coating. After hydrolysis, γ-aminopropyltriethoxysilane generates silanol groups (-Si-OH), which can form chemical bonds with plasma-treated silica, α-alumina surfaces, and resins (such as acrylic resin and polyvinyl alcohol resin) in varnishes, enhancing interfacial bonding and adhesion, thereby reducing film peeling and delamination. Sodium dodecylbenzenesulfonate can reduce surface tension, improve wettability in water-based varnishes, promote the dispersion of silica and α-alumina particles, and prevent agglomeration. Polyvinylpyrrolidone (PVP) can stabilize particles through steric hindrance, preventing sedimentation. The synergistic effect of sodium dodecylbenzenesulfonate and PVP can maintain the uniformity of water-based varnishes during storage and use, reducing leveling defects.

[0024] 2. In the manufacturing process of water-based varnish for inkjet printing, this invention incorporates 2,5-tetrahydrofurandiethanol. The 2,5-tetrahydrofurandiethanol molecule contains an ether bond (-O-) and two hydroxyl groups (-OH). The ether bond gives 2,5-tetrahydrofurandiethanol excellent oleophilicity, enabling it to dissolve or penetrate resins and polymers. The hydroxyl groups, on the other hand, endow 2,5-tetrahydrofurandiethanol with strong hydrophilicity, improving the solubility of other water-insoluble resins or additives in the water-based varnish. This results in a more uniform and stable composition, preventing layering and precipitation. Furthermore, the hydroxyl groups in the 2,5-tetrahydrofurandiethanol molecule participate in the cross-linking reaction of the resin in the water-based varnish, promoting resin film formation. This results in a denser and more uniform varnish film, improving its gloss, hardness, abrasion resistance, and water resistance, thus better protecting the film. Firstly, it protects the surface of printed materials from scratches, abrasions, and other damage. Secondly, 2,5-tetrahydrofurandimethyl alcohol can reduce the surface tension of water-based varnishes, making them easier to spread on printed surfaces, thereby improving the leveling properties of the varnish, reducing defects such as flow marks and bubbles, and resulting in a smoother and more even coating effect. Thirdly, 2,5-tetrahydrofurandimethyl alcohol can improve the flexibility of water-based varnish films. It can insert itself between resin molecular chains, reducing the intermolecular forces, allowing the film to maintain a certain degree of hardness while possessing better flexibility and folding resistance, preventing cracking during folding and bending of printed materials. Additionally, the molecular structure of 2,5-tetrahydrofurandimethyl alcohol can form hydrogen bonds or van der Waals forces with the substrate surface, improving the adhesion of water-based varnishes to paper, plastics, and other substrates, reducing film peeling and delamination.

[0025] 3. Polycarbodiimide emulsion can undergo a cross-linking reaction with the carboxyl-containing resin system in water-based varnishes to form a network structure, thereby improving the water resistance, chemical corrosion resistance, abrasion resistance, and adhesion of water-based varnishes. Ultrasonic modification can further promote the uniform mixing and reaction of polycarbodiimide with other components, improve the crosslinking effect, and avoid precipitation or stratification. Triethanolamine stearate can reduce the surface tension of water-based varnishes, improve their wettability and leveling properties, thus making the water-based varnishes smoother during the printing process. Hydroxyethyl methacrylate can participate in the film-forming process of water-based varnishes, making the formed film layer denser and more uniform, improving the gloss, hardness, and abrasion resistance of the film layer. Moreover, the hydroxyl groups (-OH) in polymethyl methacrylate can form hydrogen bonds with the crosslinking network of polycarbodiimide, enhancing the flexibility and impact resistance of the film layer. Trifluoroethyl methacrylate has excellent chemical stability. The introduced fluorine atoms can reduce the surface energy of the film layer, forming a hydrophobic structure, which can improve the weather resistance, water resistance, and stain resistance of water-based varnishes. Furthermore, the low surface tension of fluorine can improve printability. The wettability of alkyl glycosides can improve the adhesion of water-based varnishes to the substrate and reduce film peeling and delamination.

[0026] 4. In this invention, hydroxypropyl cellulose is added during the manufacturing process of water-based varnishes for inkjet printing. Hydroxypropyl cellulose increases the viscosity of the water-based varnish, improves its adhesion and spreadability, helps form a uniform and dense film, and enhances the water resistance of the water-based varnish. Polyethylene glycol can form a stable dispersion system with other components in the varnish, shortening the dispersion time, improving the gloss and hiding power of the water-based varnish, thereby improving the printability and printing quality of the varnish. At the same time, the synergistic effect of hydroxypropyl cellulose and polyethylene glycol can reduce the surface tension of the varnish, promote its uniform spreading on the substrate surface, and reduce leveling defects. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the manufacturing process of the water-based varnish of the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] like Figure 1 As shown, a method for manufacturing water-based varnish for inkjet printing includes the following steps:

[0030] S1. Weigh 45-50 parts by weight of polyvinyl alcohol resin, 6-8 parts by weight of hydroxypropyl cellulose, 2-4 parts by weight of diethylamine, 1-3 parts by weight of polyethylene glycol, and 60-65 parts by weight of deionized water. Stir and mix at 40-45℃ for 15-20 minutes, then add 25-30 parts by weight of polycarbodiimide emulsion and continue stirring for 8-12 minutes to obtain a polyvinyl alcohol resin mixed emulsion; S2. Add 40-45 parts by weight of waterborne acrylic resin, 30-38 parts by weight of the polyvinyl alcohol resin mixed emulsion, and 1 part by weight of modified silica-alumina mixture. S3. Place 0-15 parts by weight of deionized water and 45-50 parts by weight in a mixer with a speed of 600-800 rpm and mix for 30-40 minutes to obtain a mixture liquid; S4. Place the mixture liquid in a wet mill, add 4-6 parts by weight of polydimethylsiloxane, 3-5 parts by weight of sodium polyacrylate, 1-3 parts by weight of sucrose fatty acid ester, and 0.5-0.8 parts by weight of 2,5-tetrahydrofurandimethylethanol, and then wet mill to obtain a grinding material; S5. Filter the grinding material to obtain a water-based varnish with a viscosity of 10-15 mPa•s.

[0031] All raw materials used in this invention are commercially available.

[0032] Example 1:

[0033] A method for manufacturing a water-based varnish for inkjet printing, characterized by comprising the following steps:

[0034] S1. (1) Preparation of polycarbodiimide emulsion: Weigh 25 parts by weight of polycarbodiimide, 8 parts by weight of triethanolamine stearate, 7 parts by weight of hydroxyethyl methacrylate, 6 parts by weight of alkyl glycoside, 2 parts by weight of trifluoroethyl methacrylate, and 40 parts by weight of deionized water and place them in an ultrasonic device with a frequency of 80 Hz and a temperature of 40 ℃ for 30 min to obtain polycarbodiimide emulsion; (2) Preparation of polyvinyl alcohol resin mixed emulsion: Weigh 45 parts by weight of polyvinyl alcohol resin, 6 parts by weight of hydroxypropyl cellulose, 2 parts by weight of diethylamine, 1 part by weight of polyethylene glycol, and 60 parts by weight of deionized water, stir and mix them at 40 ℃ for 20 min, and then add 25 parts by weight of polycarbodiimide emulsion and continue stirring for 8 min to obtain polyvinyl alcohol resin mixed emulsion.

[0035] S2. (1) Preparation of modified silicon-aluminum mixture: Weigh 32 parts by weight of silicon dioxide and 15 parts by weight of α-alumina, mix them, and then heat them at a charge density of 1300 C / cm. 3 After being treated in a plasma device with a gas flow rate of 1.2 L / min, a treatment chamber pressure of 100 kPa, and a treatment chamber temperature of 40 °C for 5 min, it is then placed in a reactor at 90 °C with 5 parts by weight of γ-aminopropyltriethoxysilane, 3 parts by weight of sodium dodecylbenzenesulfonate, 2 parts by weight of polyvinylpyrrolidone, and 70 parts by weight of deionized water for 2.0 h to obtain a modified silicon-aluminum mixture; (2) Preparation of the mixed liquid: 40 parts by weight of waterborne acrylic resin, 30 parts by weight of polyvinyl alcohol resin mixed emulsion, 10 parts by weight of modified silicon-aluminum mixture, and 45 parts by weight of deionized water are placed in a stirrer with a speed of 600 rpm and stirred for 40 min to obtain a mixed liquid.

[0036] S3. Place the mixture obtained in S2 into a wet mill, add 4 parts by weight of polydimethylsiloxane, 3 parts by weight of sodium polyacrylate, 1 part by weight of sucrose fatty acid ester, and 0.5 parts by weight of 2,5-tetrahydrofurandimethylethanol, and grind at 3200 rpm for 60 min to obtain the grinding material.

[0037] S4. Filter the abrasive obtained in S3 to obtain a water-based varnish with a viscosity of 10 mPa•s. The filter element used for filtration has a size of 5 μm and a filtration pressure of 0.1 MPa.

[0038] Example 2:

[0039] A method for manufacturing a water-based varnish for inkjet printing, characterized by comprising the following steps:

[0040] S1. (1) Preparation of polycarbodiimide emulsion: Weigh 30 parts by weight of polycarbodiimide, 10 parts by weight of triethanolamine stearate, 8 parts by weight of hydroxyethyl methacrylate, 8 parts by weight of alkyl glycoside, 3 parts by weight of trifluoroethyl methacrylate, and 50 parts by weight of deionized water and place them in an ultrasonic device with a frequency of 90 Hz and a temperature of 50 ℃ for 25 min to obtain polycarbodiimide emulsion; (2) Preparation of polyvinyl alcohol resin mixed emulsion: Weigh 50 parts by weight of polyvinyl alcohol resin, 8 parts by weight of hydroxypropyl cellulose, 4 parts by weight of diethylamine, 3 parts by weight of polyethylene glycol, and 65 parts by weight of deionized water, stir and mix them at 45 ℃ for 15 min, and then add 30 parts by weight of polycarbodiimide emulsion and continue stirring for 12 min to obtain polyvinyl alcohol resin mixed emulsion.

[0041] S2. (1) Preparation of modified silicon-aluminum mixture: Weigh 35 parts by weight of silicon dioxide and 20 parts by weight of α-alumina, mix them, and then heat them at a charge density of 1400 C / cm. 3 After being treated in a plasma device with a gas flow rate of 1.5 L / min, a treatment chamber pressure of 110 kPa, and a treatment chamber temperature of 50 °C for 3 min, it is then placed in a reactor at 95 °C with 7 parts by weight of γ-aminopropyltriethoxysilane, 5 parts by weight of sodium dodecylbenzenesulfonate, 4 parts by weight of polyvinylpyrrolidone, and 80 parts by weight of deionized water for 1.5 h to obtain a modified silicon-aluminum mixture; (2) Preparation of the mixed liquid: 45 parts by weight of waterborne acrylic resin, 38 parts by weight of polyvinyl alcohol resin mixed emulsion, 15 parts by weight of modified silicon-aluminum mixture, and 50 parts by weight of deionized water are placed in a stirrer with a speed of 800 rpm and stirred for 30 min to obtain a mixed liquid.

[0042] S3. Place the mixture obtained in S2 into a wet mill, add 6 parts by weight of polydimethylsiloxane, 5 parts by weight of sodium polyacrylate, 3 parts by weight of sucrose fatty acid ester, and 0.8 parts by weight of 2,5-tetrahydrofurandimethylethanol, and grind for 50 minutes at a speed of 3500 rpm to obtain the grinding material.

[0043] S4. Filter the abrasive obtained in S3 to obtain a water-based varnish with a viscosity of 15 mPa•s. The filter element used for filtration has a size of 2 μm and a filtration pressure of 0.2 MPa.

[0044] Example 3:

[0045] A method for manufacturing a water-based varnish for inkjet printing, characterized by comprising the following steps:

[0046] S1. (1) Preparation of polycarbodiimide emulsion: Weigh 28 parts by weight of polycarbodiimide, 9 parts by weight of triethanolamine stearate, 8 parts by weight of hydroxyethyl methacrylate, 7 parts by weight of alkyl glycoside, 2.5 parts by weight of trifluoroethyl methacrylate, and 45 parts by weight of deionized water and place them in an ultrasonic device with a frequency of 85Hz and a temperature of 45℃ for 28 minutes to obtain polycarbodiimide emulsion; (2) Preparation of polyvinyl alcohol resin mixed emulsion: Weigh 48 parts by weight of polyvinyl alcohol resin, 7 parts by weight of hydroxypropyl cellulose, 3 parts by weight of diethylamine, 2 parts by weight of polyethylene glycol, and 62 parts by weight of deionized water, stir and mix them at 42℃ for 18 minutes, and then add 26 parts by weight of polycarbodiimide emulsion and continue stirring for 10 minutes to obtain polyvinyl alcohol resin mixed emulsion.

[0047] S2. (1) Preparation of modified silicon-aluminum mixture: Weigh 33 parts by weight of silicon dioxide and 18 parts by weight of α-alumina, mix them, and then heat them at a charge density of 1300 C / cm. 3 After being treated in a plasma device with a gas flow rate of 1.4 L / min, a treatment chamber pressure of 100 kPa, and a treatment chamber temperature of 45 °C for 4 min, it is then placed in a reactor at 92 °C with 6 parts by weight of γ-aminopropyltriethoxysilane, 4 parts by weight of sodium dodecylbenzenesulfonate, 3 parts by weight of polyvinylpyrrolidone, and 75 parts by weight of deionized water for 1.5 h to obtain a modified silicon-aluminum mixture; (2) Preparation of the mixed liquid: 42 parts by weight of waterborne acrylic resin, 35 parts by weight of polyvinyl alcohol resin mixed emulsion, 12 parts by weight of modified silicon-aluminum mixture, and 48 parts by weight of deionized water are placed in a stirrer with a speed of 700 rpm and stirred for 35 min to obtain a mixed liquid.

[0048] S3. Place the mixture obtained in S2 into a wet mill, add 5 parts by weight of polydimethylsiloxane, 4 parts by weight of sodium polyacrylate, 2 parts by weight of sucrose fatty acid ester, and 0.6 parts by weight of 2,5-tetrahydrofurandimethylethanol, and grind at 3300 rpm for 55 min to obtain the grinding material.

[0049] S4. Filter the abrasive obtained in S3 to obtain a water-based varnish with a viscosity of 12 mPa•s. The filter element used for filtration has a size of 4 μm and a filtration pressure of 0.2 MPa.

[0050] Comparative Example 1:

[0051] The difference from Example 1 is that the modified silicon-aluminum mixture in Example 1 is removed.

[0052] Comparative Example 2:

[0053] The difference from Example 1 is that the silicon dioxide and α-alumina in S2 are not modified. Specifically, a silicon-alumina mixture obtained by mixing 32 parts by weight of silicon dioxide, 15 parts by weight of α-alumina, and 70 parts by weight of deionized water is used instead of the modified silicon-alumina mixture.

[0054] Comparative Example 3:

[0055] The difference from Example 1 is that 2,5-tetrahydrofurandimethylol is removed from Example 1.

[0056] Comparative Example 4:

[0057] The difference from Example 1 is that the polycarbodiimide emulsion in Example 1 is removed.

[0058] Comparative Example 5:

[0059] The difference from Example 1 is that the hydroxypropyl cellulose in Example 1 is removed.

[0060] The water-based varnishes manufactured in Examples 1, 2, and 3 and Comparative Examples 1, 2, 3, 4, and 5 were subjected to performance tests.

[0061] Gloss was tested according to GB / T 7706-2008 "Relief Printing"; abrasion resistance was tested according to GB / T 1768-2006 "Determination of Abrasion Resistance of Paints and Varnishes - Rotating Rubber Wheel Method"; adhesion was tested according to GB / T 9286-2021 "Cross-cut Test of Paints and Varnishes".

[0062] Water resistance test: The water-based varnishes prepared in Examples 1, 2, 3 and Comparative Examples 1, 2, 3, 4, 5 were sprayed onto the substrate with graphics and text, and after being fully dried, they were placed under the conditions of temperature (30±2)℃ and relative humidity (85±5)%RH for 20min, 40min, and 60min to observe the water resistance of the water-based varnishes. The water resistance evaluation criteria of water-based varnishes are shown in Table 1.

[0063] Table 1: Evaluation Standards for Water Resistance of Water-Based Varnishes

[0064]

[0065] Table 2 shows the performance test results of the water-based varnishes. As shown in Table 2, the water-based varnishes manufactured in Examples 1, 2, and 3 have high gloss values ​​and only fade after more than 976 rubs. Their adhesion level is 0, the coating does not peel off, and the water resistance score is still above 92 after 60 minutes. The gloss of Comparative Examples 3, 4, and 5 is significantly lower than that of the examples. Comparative Examples 1, 2, 3, and 4 have fewer abrasion cycles, and their adhesion levels are lower, at 3 and 4, respectively, with coating peeling off. The water resistance of the comparative examples is poor; after 60 minutes, the water resistance score of the comparative examples is below 90, and the water resistance scores of Comparative Examples 3 and 4 are below 80 after 60 minutes.

[0066] It is evident that modification with silica and α-alumina enhances interfacial bonding, improves adhesion and abrasion resistance, and reduces film peeling and delamination. The hydroxyl groups in 2,5-tetrahydrofurandimethyl alcohol can participate in the cross-linking reaction of the resin in water-based varnishes, promoting resin film formation. This results in a denser and more uniform varnish film, improving gloss, hardness, abrasion resistance, and water resistance. Furthermore, the molecular structure of 2,5-tetrahydrofurandimethyl alcohol can form hydrogen bonds or van der Waals forces with the substrate surface, improving the adhesion of water-based varnishes to paper, plastics, and other substrates, reducing film peeling and delamination. Polycarbodiimide emulsion can undergo cross-linking reactions with carboxyl-containing resin systems in water-based varnishes, forming a network structure. This improves the water resistance, chemical corrosion resistance, abrasion resistance, and adhesion of the water-based varnish. Poly(hydroxyethyl methacrylate) can participate in the film-forming process of water-based varnishes, making the formed film denser and more uniform, improving gloss, hardness, and abrasion resistance. Hydroxypropyl cellulose can increase the viscosity of water-based varnishes, improve their adhesion and spreadability, help form a uniform and dense film, and enhance the water resistance of water-based varnishes. Polyethylene glycol can form a stable dispersion system with other components in the varnish, shorten the dispersion time, and improve the gloss of the varnish.

[0067] Table 2: Performance Test Table for Water-Based Varnishes

[0068]

[0069] In summary, the water-based varnish for inkjet printing manufactured by this invention has good gloss, good abrasion resistance, strong adhesion, and good water resistance. Moreover, the manufacturing method is simple and suitable for large-scale promotion and use.

[0070] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. A method for manufacturing a water-based varnish for inkjet printing, characterized in that, Includes the following steps: S1. Weigh 45-50 parts by weight of polyvinyl alcohol resin, 6-8 parts by weight of hydroxypropyl cellulose, 2-4 parts by weight of diethylamine, 1-3 parts by weight of polyethylene glycol, and 60-65 parts by weight of deionized water. Stir and mix at 40-45°C for 15-20 minutes. Then add 25-30 parts by weight of polycarbodiimide emulsion and continue stirring for 8-12 minutes to obtain a polyvinyl alcohol resin mixed emulsion. S2. Place 40-45 parts by weight of waterborne acrylic resin, 30-38 parts by weight of polyvinyl alcohol resin mixed emulsion, 10-15 parts by weight of modified silica-alumina mixture, and 45-50 parts by weight of deionized water in a mixer with a speed of 600-800 rpm and stir for 30-40 minutes to obtain a mixed liquid. S3. Place the mixture obtained in S2 into a wet mill, add 4-6 parts by weight of polydimethylsiloxane, 3-5 parts by weight of sodium polyacrylate, 1-3 parts by weight of sucrose fatty acid ester, and 0.5-0.8 parts by weight of 2,5-tetrahydrofurandimethylethanol, and then wet mill to obtain the grinding material. S4. Filter the abrasive obtained in S3 to obtain a water-based varnish with a viscosity of 10-15 mPa·s; The polycarbodiimide emulsion was prepared by the following method: Weigh 25-30 parts by weight of polycarbodiimide, 8-10 parts by weight of triethanolamine stearate, 7-8 parts by weight of polyhydroxyethyl methacrylate, 6-8 parts by weight of alkyl glycoside, 2-3 parts by weight of trifluoroethyl methacrylate, and 40-50 parts by weight of deionized water, and place them in an ultrasonic device for 25-30 minutes to obtain a polycarbodiimide emulsion. The modified silicon-aluminum mixture was prepared by the following method: Weigh out 32-35 parts by weight of silicon dioxide and 15-20 parts by weight of α-alumina, mix them, and treat them in a plasma device for 3-5 minutes. Then, place them together with 5-7 parts by weight of γ-aminopropyltriethoxysilane, 3-5 parts by weight of sodium dodecylbenzenesulfonate, 2-4 parts by weight of polyvinylpyrrolidone, and 70-80 parts by weight of deionized water in a reaction vessel to obtain a modified silicon-aluminum mixture.

2. The method for manufacturing a water-based varnish for inkjet printing according to claim 1, characterized in that, The wet grinding mill operates at a speed of 3200–3500 rpm and a grinding time of 50–60 min.

3. The method for manufacturing a water-based varnish for inkjet printing according to claim 1, characterized in that, The wet grinding mill uses steel balls as the grinding medium, with a particle size of 0.6–0.8 mm.

4. The method for manufacturing a water-based varnish for inkjet printing according to claim 1, characterized in that, The filter element used in the filtration process has a size of 2-5 μm and a filtration pressure of 0.1-0.2 MPa.

5. The method for manufacturing a water-based varnish for inkjet printing according to claim 1, characterized in that, The ultrasonic device has a frequency of 80-90 Hz and a temperature of 40-50℃.

6. The method for manufacturing a water-based varnish for inkjet printing according to claim 1, characterized in that, The charge density of the plasma device is 1300–1400 C / cm³. 3 The gas flow rate is 1.2–1.5 L / min, the processing chamber pressure is 100–110 kPa, and the processing chamber temperature is 40–50 °C.

7. The method for manufacturing a water-based varnish for inkjet printing according to claim 1, characterized in that, The reaction temperature in the reactor is 90–95°C, and the reaction time is 1.5–2.0 h.

8. A water-based varnish for inkjet printing, characterized in that, It is manufactured by any one of the manufacturing methods of claims 1 to 7.

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