Thermal foaming water-based ink as well as preparation method and application thereof
By optimizing the formulation and preparation process of thermally foamed water-based inks, the problems of environmental pollution, unstable print quality, and weak adhesion of inkjet printer inks have been solved, achieving efficient and environmentally friendly printing results suitable for a variety of printing media.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-13
- Publication Date
- 2026-03-10
AI Technical Summary
Existing inkjet printer inks suffer from environmental pollution, unstable print quality, weak adhesion, and low printing efficiency, especially on low surface energy media.
The formula of thermally foamed water-based ink is adopted. The resin is neutralized by alkaline aqueous solution and high pressure homogenization is combined to achieve nanoscale dispersion of pigments. The surfactant is selected and compounded, and water-soluble organic solvents are used to improve the evaporation rate of water. The ink is stored in the dark during the preparation process.
It achieves high printing quality, strong adhesion, fast drying, environmentally friendly low odor, and good thermal foaming stability, making it suitable for office and food contact scenarios.
Smart Images
Figure CN121628433A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of printing ink technology, and in particular to a thermally foaming water-based ink, its preparation method, and its application. Background Technology
[0002] Thermal inkjet inks are primarily used in thermal inkjet printers. These printers utilize the on-demand inkjet principle, where "the heating element instantly heats up to propel ink droplets out." They offer advantages such as simple structure, high printing resolution, and easy maintenance, and can be widely used in packaging labels, digital printing, and other scenarios. They are compatible with various printing media, including paper, synthetic resin films, and fabrics.
[0003] Current inkjet printer inks have significant limitations: solvent-based inks contain a large amount of VOCs, which volatilize and pollute the environment during printing, and have a pungent odor, making them unsuitable for enclosed printing scenarios such as offices or homes; curing inks have lower VOC emissions, but require a UV / EB curing device, increasing printer costs, and residual components can easily cause printed parts to have an odor, making them unsuitable for everyday document or food contact printing needs.
[0004] Thermally foamed water-based inks, using water as the primary solvent, meet the environmentally friendly and low-odor requirements of inkjet printers. However, they face compatibility challenges: the instantaneous temperature rise of the printer's heating element (80~120 ℃) can easily lead to unstable ink foaming, resulting in blurred text and image defects; when applied to low surface energy materials such as coated paper, the ink adhesion is weak, and printed parts are easily rubbed off; furthermore, the slow evaporation of water can cause smudging on subsequent pages during continuous printing, limiting printing efficiency. Therefore, developing high-performance thermally foamed water-based inks compatible with inkjet printers is key to overcoming current application pain points. Summary of the Invention
[0005] To address the aforementioned technical problems, this invention provides a thermally foaming water-based ink, its preparation method, and its application. The thermally foaming water-based ink contains pigments, polymers, water-soluble organic solvents, a large amount of water, and surfactants. The thermally foaming water-based ink prepared by the method of this invention has advantages such as high print quality, strong printability, lower ink density compared to solvent-based inkjet inks, and lower environmental pollution.
[0006] To achieve this technical objective, the present invention adopts the following solution:
[0007] In a first aspect, the present invention provides a method for preparing a thermally foaming water-based ink, comprising the following steps: S1. Place a certain amount of polymer in a beaker, add a certain amount of organic solvent, stir until completely dissolved, then add alkaline aqueous solution and deionized water, and stir at high speed to form a uniform emulsion. S2. Add a certain amount of pigment and the first surfactant under high-speed stirring, disperse under high-speed shearing for a certain time, and then transfer the dispersion to a high-pressure homogenizer tank. Circulate and disperse under a certain pressure for a certain number of times to obtain a dispersion. Distill the obtained dispersion under reduced pressure until there is no odor of organic solvent or alkaline solvent, to obtain an aqueous dispersion containing pigment. S3. Add water-soluble organic solvent, second surfactant and deionized water to a beaker in sequence, and disperse evenly by ultrasonication to obtain a mixed solution; take a certain amount of water dispersion containing pigment and slowly add it to the mixed solution, stir continuously until evenly mixed, and then process it with a high-pressure homogenizer to obtain the finished water-based ink, and store it away from light.
[0008] Furthermore, the present invention provides a method for preparing a thermally foaming water-based ink, wherein the amount of each component is measured in parts by weight.
[0009] Further, in step S1, the polymer can be a water-based resin such as polyacrylic acid resin, polyurethane resin, or epoxy resin, and the molecular weight of the resin can be 10,000 to 200,000, specifically 10,000 to 20,000, 20,000 to 50,000, 50,000 to 100,000, 100,000 to 150,000, or 150,000 to 200,000. The amount of polymer can be 15 to 65 parts, specifically 15 to 25 parts, 25 to 35 parts, 35 to 45 parts, 45 to 55 parts, or 55 to 65 parts.
[0010] Further, in step S1, the organic solvent can be an alcohol solvent, a ketone solvent, an ether solvent, etc., specifically one of acetone, methyl ethyl ketone, methyl isobutyl ketone, ethanol, isopropanol, dibutyl ether, tetrahydrofuran, and dioxane. The amount of organic solvent can be 40 to 100 parts, specifically 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, 90 parts, and 100 parts.
[0011] Further, in step S1, the stirring speed can be 300~1000 rap / min, specifically 300 rap / min, 400 rap / min, 500 rap / min, 600 rap / min, 700 rap / min, 800 rap / min, 900 rap / min, or 1000 rap / min; The speed of high-speed stirring can be 1000~5000 rap / min, specifically 1000 rap / min, 2000 rap / min, 3000 rap / min, 4000 rap / min, and 5000 rap / min.
[0012] Further, in step S1, the alkali added to the alkaline aqueous solution can be lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, etc., specifically either sodium hydroxide or ammonia; the amount of alkaline aqueous solution can be 10-50 parts, specifically 10-20 parts, 20-30 parts, 30-40 parts, or 40-50 parts. The mass concentration of the alkaline aqueous solution is 10-20%, specifically 10%, 15%, or 20%.
[0013] Furthermore, in step S1, the amount of deionized water added can be 100-400 parts, specifically 100-150 parts, 150-200 parts, 200-300 parts, or 300-400 parts.
[0014] Furthermore, in step S2, the added pigment can be an organic pigment or an inorganic pigment. Specifically, the inorganic pigment can be carbon black, metal oxides, metal chlorides, etc., and the carbon black can be furnace black, acetylene black, etc. The organic pigment can be azo pigment, diazo pigment, phthalocyanine pigment, quinacridone pigment, isoindolinone pigment, dioxazine pigment, perylene pigment, anthraquinone pigment, etc.; the amount of pigment can be 20-80 parts, specifically 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, or 80 parts.
[0015] Furthermore, in step S2, the first surfactant added can be a wetting agent, dispersant, viscosity modifier, defoamer, leveling agent, brightener, etc.; the amount of the first surfactant can be 1 to 20 parts, specifically 1 to 5 parts, 6 to 10 parts, 11 to 15 parts, or 16 to 20 parts.
[0016] The first surfactants are all commonly used substances in the ink industry. For example, wetting agents can be fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, polyether-modified silicone oils, etc., such as Emulsogen LCN 407, BYK 346, TEGO Glide 410, etc.; dispersants can be ammonium polyacrylates, polycarboxylates, polyester dispersants, etc., such as Dispersogen 2774, Dispersogen PTS, EFKA 4585, etc.; viscosity modifiers can be hydroxyethyl cellulose, polyacrylamide, bentonite, etc., such as Rheovis PE1331, Rheovis HS 1152, Natrosol Plus 330, etc.; defoamers can be polydimethylsiloxane, mineral oil-based defoamers, polyether defoamers, etc., such as BYK 024, D-Foam-R C740, Foamaster, etc. 111, etc.; leveling agents can be polyether-modified silicone oil, acrylate copolymers, fluorinated polymers, etc., such as BYK-3400, BYK-358N, BYK-011, etc.; brighteners can be polyurethane emulsions, amino-modified silicone oils, epoxy-modified silicone oils, etc., such as XB 530, XB 540, BYK-333, etc.
[0017] Furthermore, in step S2, the speed of the high-speed stirring can be 4000~10000 rap / min, specifically 4000 rap / min, 5000 rap / min, 6000 rap / min, 7000 rap / min, 8000 rap / min, 9000 rap / min, or 10000 rap / min; The high-speed shear dispersion time can be 30~90 min, specifically 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, and 90 min; The pressure of the high-pressure homogenizer can be 800~1800 bar, specifically 800~1000 bar, 1000~1200 bar, 1200~1400 bar, 1400~1600 bar, and 1600~1800 bar; The number of homogenization cycles can be 15 to 25, specifically 15 to 17, 17 to 19, 19 to 21, 21 to 23, or 23 to 25. The temperature for vacuum distillation can be 25~85℃, specifically 25~35℃, 35~45℃, 45~55℃, 55~65℃, 65~75℃, and 75~85℃.
[0018] Further, in step S3, the water-soluble organic solvent can be a polyol and its ether, an acetate, etc., specifically ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerol, trimethylolpropane, diethylene glycol diethyl ether; the amount of water-soluble organic solvent can be 0.5 to 10 parts, specifically 0.5 to 2.5 parts, 2.5 to 4.5 parts, 4.5 to 6.5 parts, 6.5 to 8.5 parts, or 8.5 to 10 parts.
[0019] Furthermore, in step S3, the second surfactant added can be a wetting agent, dispersant, viscosity modifier, defoamer, leveling agent, brightener, etc.; the amount of the second surfactant can be 1 to 20 parts, specifically 1 to 5 parts, 6 to 10 parts, 11 to 15 parts, or 16 to 20 parts.
[0020] The second surfactant consists of commonly used substances in the ink industry. For example, wetting agents can be fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, polyether-modified silicone oils, etc., such as Emulsogen LCN 407, BYK 346, TEGO Glide 410, etc.; dispersants can be ammonium polyacrylates, polycarboxylate salts, polyester dispersants, etc., such as Dispersogen 2774, Dispersogen PTS, EFKA 4585, etc.; viscosity modifiers can be hydroxyethyl cellulose, polyacrylamide, bentonite, etc., such as Rheovis PE1331, Rheovis HS 1152, Natrosol Plus 330, etc.; defoamers can be polydimethylsiloxane, mineral oil-based defoamers, polyether defoamers, etc., such as BYK 024, D-Foam-R C740, Foamaster, etc. 111, etc.; leveling agents can be polyether-modified silicone oil, acrylate copolymers, fluorinated polymers, etc., such as BYK-3400, BYK-358N, BYK-011, etc.; brighteners can be polyurethane emulsions, amino-modified silicone oils, epoxy-modified silicone oils, etc., such as XB 530, XB 540, BYK-333, etc.
[0021] Furthermore, in step S3, the amount of deionized water added can be 50-200 parts, specifically 50-100 parts, 100-150 parts, or 150-200 parts.
[0022] Furthermore, in step S3, the ultrasonic time of the ultrasonic machine can be 0.5h to 2.5h, specifically 0.5h to 1h, 1h to 1.5h, 2h to 2.5h, 0.5h, 1h, 2h or 2.5h; The stirring speed for uniform dissolution can be 300~1000 rap / min, specifically 300 rap / min, 400 rap / min, 500 rap / min, 600 rap / min, 700 rap / min, 800 rap / min, 900 rap / min, and 1000 rap / min; The pressure of the high-pressure homogenizer can be 800~1800 bar, specifically 800~1000 bar, 1000~1200 bar, 1200~1400 bar, 1400~1600 bar, and 1600~1800 bar; The number of homogenization cycles can be 5 to 50, specifically 5 to 10, 10 to 20, 20 to 30, 30 to 40, or 40 to 50.
[0023] Secondly, the present invention provides a thermally foaming water-based ink prepared by the aforementioned preparation method.
[0024] Thirdly, the present invention provides a method for applying the aforementioned thermally foamed water-based ink to a thermally foamed inkjet printer.
[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0026] The thermally foaming water-based ink prepared by this invention exhibits beneficial effects such as high print quality, strong adhesion, fast drying, environmental friendliness, low odor, and good thermal foaming stability. These effects stem from the systematic optimization of the formulation and process: neutralizing the resin with an alkaline aqueous solution and adjusting the system stability, combined with high-pressure homogenization to achieve nanoscale dispersion of pigments, ensuring uniform ink droplets and clear images; optimizing the surfactant blend and using a suitable polymer molecular weight to improve wetting, film formation, and adhesion; introducing water-soluble organic solvents to increase the water evaporation rate while preventing printhead drying, balancing drying efficiency and printing reliability; using water as the main solvent significantly reduces VOCs and eliminates the need for UV curing, making it suitable for office and food contact applications. The overall synergistic effect ensures stable foam during the thermal foaming process and strong printability. Attached Figure Description
[0027] Figure 1 A flowchart for preparing the finished ink.
[0028] Figure 2 The image shows the contact angle of the ink prepared in Example 1.
[0029] Figure 3 The image shows the TEM test results of the ink prepared in Example 1.
[0030] Figure 4 The image shows the contact angle of the ink prepared in Example 2.
[0031] Figure 5 The image shows the contact angle of the ink prepared in Example 3.
[0032] Figure 6 The image shows the contact angle of the ink prepared in Example 4.
[0033] Figure 7 The viscosity-temperature curve of the ink prepared in Example 4 is shown in the figure.
[0034] Figure 8 This is a contact angle diagram of the ink prepared in Example 5.
[0035] Figure 9 This is an inkjet printing effect diagram of the ink prepared in Example 5.
[0036] Figure 10 The contact angle diagram is for the ink prepared in Comparative Example 1.
[0037] Figure 11 The inkjet printing effect of the ink prepared in Comparative Example 1 is shown in the image.
[0038] Figure 12 The contact angle diagram is for the ink prepared in Comparative Example 2.
[0039] Figure 13 The inkjet printing effect of the ink prepared in Comparative Example 2 is shown in the figure. Detailed Implementation
[0040] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.
[0041] Please see Figure 1 This invention provides a method for preparing a thermally foaming water-based ink. Unless otherwise specified, the experimental methods used in the embodiments and comparative examples of this invention are conventional methods. Unless otherwise specified, all materials and reagents used are commercially available. Example 1
[0042] (1) Synthesizing aqueous dispersions containing pigments
[0043] S1. Place 25 parts of polyacrylic acid resin (molecular weight 10000) in a beaker, add 60 parts of acetone as an organic solvent, and stir at 500 rap / min until completely dissolved. Then add 20 parts of sodium hydroxide aqueous solution (concentration 10%) and 120 parts of deionized water, and stir at 3000 rap / min to form a homogeneous emulsion.
[0044] S2. Under high-speed stirring at 5000 rap / min, add 40 parts of carbon black pigment and 5 parts of the first surfactant (dispersant Dispersogen 2774) to the above emulsion, and continue high-speed shear dispersion for 60 min. Transfer the dispersion to a high-pressure homogenizer tank and circulate it 20 times at 800 bar. Distill the resulting dispersion under reduced pressure at 80°C until there is no organic solvent or alkaline solvent odor, to obtain an aqueous dispersion containing pigment.
[0045] (2) Preparation of finished ink
[0046] S3. In a beaker, add 2 parts ethylene glycol as a water-soluble organic solvent, 3 parts of the second surfactant (leveling agent BYK-3400), and 100 parts deionized water sequentially. Disperse the mixture using ultrasound for 1 hour to obtain a mixed solution. Slowly add 20 parts of the above-mentioned water dispersion containing pigment to the mixed solution and stir continuously at 700 rpm until homogeneous. Then, process the mixture 20 times using a high-pressure homogenizer at 1400 bar to obtain the finished water-based ink. Store the ink away from light.
[0047] The contact angle of the water-based ink prepared in this embodiment is as follows: Figure 2 As shown, the contact angle is 52.5°. TEM tests of the prepared ink are as follows. Figure 3 As shown, the prepared ink has a relatively low surface tension, which may result in good wetting and adhesion on materials with medium or low surface energy. The carbon black particles in the ink are all less than 100 nm in size. Example 2
[0048] (1) Synthesizing aqueous dispersions containing pigments
[0049] S1. Place 40 parts of polyurethane resin (molecular weight 100,000) in a beaker, add 70 parts of ethanol as an organic solvent, and stir at 400 rpm until completely dissolved. Then add 30 parts of ammonia solution (concentration 10%) and 250 parts of deionized water, and stir at 2000 rpm to form a homogeneous emulsion.
[0050] S2. Under high-speed stirring at 7000 rap / min, add 30 parts of furnace black pigment and 10 parts of the first surfactant (wetting agent Emulsogen LCN 407) to the above emulsion, and continue high-speed shear dispersion for 40 minutes. Transfer the dispersion to a high-pressure homogenizer tank and circulate it 18 times at 800 bar pressure. Perform vacuum distillation on the resulting dispersion at 35°C until there is no organic solvent or alkaline solvent odor, to obtain an aqueous dispersion containing pigment.
[0051] (2) Preparation of finished ink
[0052] S3. In a beaker, add 10 parts propylene glycol as a water-soluble organic solvent, 8 parts a second surfactant (defoamer D-Foam-R C740), and 150 parts deionized water sequentially. Disperse the mixture using ultrasound for 1.5 hours to obtain a mixed solution. Slowly add 60 parts of the above-mentioned pigmented aqueous dispersion to the mixed solution and stir continuously at 500 rpm until homogeneous. Then, process the mixture 30 times using a high-pressure homogenizer at 900 bar to obtain the finished water-based ink. Store the ink away from light.
[0053] The contact angle of the water-based ink prepared in this embodiment is as follows: Figure 4 As shown, with a contact angle of 31.4°, the prepared ink exhibits excellent wetting and spreading capabilities. Example 3
[0054] (1) Synthesizing aqueous dispersions containing pigments
[0055] S1. Place 45 parts of epoxy resin (molecular weight 150,000) in a beaker, add 80 parts of methyl isobutyl ketone as an organic solvent, and stir at 600 rpm until completely dissolved. Then add 40 parts of potassium hydroxide aqueous solution (concentration 10%) and 300 parts of deionized water, and stir at 4000 rpm to form a homogeneous emulsion.
[0056] S2. Under high-speed stirring at 4000 rap / min, add 60 parts of acetylene black pigment and 15 parts of the first surfactant (dispersant Dipersogen 2774) to the above emulsion, and continue high-speed shear dispersion for 80 minutes. Transfer the dispersion to a high-pressure homogenizer tank and circulate it 22 times at 800 bar pressure. Distill the resulting dispersion under reduced pressure at 65°C until there is no organic solvent or alkaline solvent odor, to obtain an aqueous dispersion containing the pigment.
[0057] (2) Preparation of finished ink
[0058] S3. In a beaker, add 3 parts diethylene glycol as a water-soluble organic solvent, 12 parts of the second surfactant (leveling agent BYK-358N), and 80 parts deionized water sequentially. Disperse the mixture using ultrasound for 2 hours to obtain a mixed solution. Slowly add 70 parts of the above-mentioned water dispersion containing pigment to the mixed solution and stir continuously at 800 rpm until homogeneous. Then, process the mixture 40 times using a high-pressure homogenizer at 1000 bar to obtain the finished water-based ink. Store the ink away from light.
[0059] The contact angle of the water-based ink prepared in this embodiment is as follows: Figure 5 As shown, the contact angle is 55.2°, and the prepared ink has good wetting and spreading ability. Example 4
[0060] (1) Synthesizing aqueous dispersions containing pigments
[0061] S1. Place 55 parts of polyacrylic acid resin (molecular weight 20000) in a beaker, add 90 parts of isopropanol as an organic solvent, and stir at 700 rap / min until completely dissolved. Then add 50 parts of methylamine aqueous solution (concentration 20%) and 350 parts of deionized water, and stir at 5000 rap / min to form a homogeneous emulsion.
[0062] S2. Under high-speed stirring at 10000 rap / min, add 70 parts carbon black and 20 parts of the first surfactant (viscosity modifier Rheovis PE 1331) to the above emulsion, and continue high-speed shear dispersion for 90 minutes. Transfer the dispersion to a high-pressure homogenizer tank and circulate it 25 times at 800 bar pressure. Distill the resulting dispersion under reduced pressure at 75°C until there is no organic solvent or alkaline solvent odor, to obtain an aqueous dispersion containing pigment.
[0063] (2) Preparation of finished ink
[0064] S3. In a beaker, add 4.5 parts glycerol as a water-soluble organic solvent, 8 parts a second surfactant (5 parts brightener BYK-333 and 3 parts leveling agent BYK-011), and 200 parts deionized water sequentially. Disperse the mixture using ultrasound for 2.5 hours to obtain a mixed solution. Slowly add 80 parts of the above-mentioned pigmented aqueous dispersion to the mixed solution and stir continuously at 900 rpm until homogeneous. Then, use a high-pressure homogenizer to process the mixture 50 times at 1000 bar to obtain the finished water-based ink. Store the ink away from light.
[0065] The contact angle of the water-based ink prepared in this embodiment is as follows: Figure 6 As shown, with a contact angle of 21.9°, the prepared ink exhibits excellent wetting and spreading abilities. The viscosity-temperature profile of the prepared ink is shown below. Figure 7 As shown, the ink has the lowest viscosity at 85°C, and then the viscosity increases sharply as the temperature rises. Example 5
[0066] (1) Synthesizing aqueous dispersions containing pigments
[0067] S1. Place 15 parts of polyurethane resin (molecular weight 10000) in a beaker, add 40 parts of dibutyl ether as an organic solvent, and stir at 300 rap / min until completely dissolved. Then add 10 parts of triethylamine aqueous solution (concentration 15%) and 150 parts of deionized water, and stir at 1000 rap / min to form a homogeneous emulsion.
[0068] S2. Under high-speed stirring at 6000 rap / min, add 20 parts of acetylene black pigment and 1 part of the first surfactant (defoamer D-Foam-R C740) to the above emulsion, and continue high-speed shear dispersion for 30 minutes. Transfer the dispersion to a high-pressure homogenizer tank and circulate it 15 times at 1000 bar pressure. Perform vacuum distillation on the resulting dispersion at 25 °C until there is no organic solvent or alkaline solvent odor, to obtain an aqueous dispersion containing the pigment.
[0069] (2) Preparation of finished ink
[0070] S3. In a beaker, add 0.5 parts triethylene glycol as a water-soluble organic solvent, 1 part of the second surfactant (wetting agent Emulsogen LCN 407), and 50 parts deionized water sequentially. Disperse the mixture using ultrasound for 0.5 hours to obtain a mixed solution. Slowly add 30 parts of the above-mentioned water dispersion containing pigment to the mixed solution and stir continuously at 300 rpm until homogeneous. Then, process the mixture 15 times using a high-pressure homogenizer at 1000 bar to obtain the finished water-based ink. Store the ink away from light.
[0071] The contact angle of the water-based ink prepared in this embodiment is as follows: Figure 8 As shown, with a contact angle of 32.1°, the prepared ink exhibits excellent wetting and spreading abilities. The inkjet printing effect of the prepared ink is as follows... Figure 9 As shown, it can be clearly seen that the printed fine text has extremely high resolution and edge sharpness.
[0072] Comparative Example 1
[0073] (1) Synthesizing aqueous dispersions containing pigments
[0074] S1. Place 25 parts of polyacrylic acid resin (molecular weight 5000) in a beaker, add 60 parts of acetone as an organic solvent, and stir at 500 rpm until dissolved. Then add 20 parts of sodium hydroxide aqueous solution (concentration 10%) and 120 parts of deionized water, and stir at 3000 rpm to form an emulsion.
[0075] S2. Under high-speed stirring at 5000 rap / min, add 40 parts of carbon black pigment and 5 parts of the first surfactant (dispersant Dipersogen 2774) to the above emulsion, and continue high-speed shear dispersion for 30 minutes. Transfer the dispersion to a high-pressure homogenizer tank and circulate it 10 times under a pressure of 500 bar. Distill the resulting dispersion under reduced pressure at 60°C until there is no organic solvent or alkaline solvent odor, to obtain an aqueous dispersion containing pigment.
[0076] (2) Preparation of finished ink
[0077] S3. In a beaker, add 2 parts ethylene glycol as a water-soluble organic solvent, 3 parts of the second surfactant (leveling agent BYK 011), and 100 parts deionized water in sequence. Disperse the mixture using ultrasound for 0.5 hours to obtain a mixed solution. Slowly add 20 parts of the above-mentioned water dispersion containing pigment to the mixed solution and stir continuously at 700 rpm until homogeneous. Then, process the mixture 10 times using a high-pressure homogenizer at 800 bar to obtain the finished water-based ink. Store the ink away from light.
[0078] In this comparative example, the polymer molecular weight was low (5000), and the high-pressure homogenization pressure was low (500 bar), resulting in fewer cycles and insufficient pigment dispersion uniformity. The contact angle of the prepared ink was as follows: Figure 10 As shown, the contact angle is 62.6°, the surface tension is high, and the adhesion on coated paper is weak; some of it peels off after light rubbing. The inkjet printing effect of the prepared ink is as follows. Figure 11 As shown, it can be clearly seen that microparticles of ink are deposited during the printing process, and the edges of the printed text are slightly blurred.
[0079] Comparative Example 2
[0080] (1) Synthesizing aqueous dispersions containing pigments
[0081] S1. Place 40 parts of polyurethane resin (molecular weight 200,000) in a beaker, add 70 parts of ethanol as an organic solvent, and stir at 400 rpm until dissolved. Then add 30 parts of ammonia solution (10% concentration) and 250 parts of deionized water, and stir at 2000 rpm to form an emulsion.
[0082] S2. Under high-speed stirring at 7000 rap / min, 30 parts of furnace black pigment were added to the above emulsion without adding surfactant, and high-speed shear dispersion was continued for 40 minutes. The dispersion was transferred to a high-pressure homogenizer tank and circulated 18 times at 800 bar pressure. The resulting dispersion was subjected to vacuum distillation at 35°C until no organic solvent or alkaline solvent odor was detected, yielding an aqueous dispersion containing pigment.
[0083] (2) Preparation of finished ink
[0084] S3. In a beaker, add 10 parts propylene glycol as a water-soluble organic solvent and 150 parts deionized water sequentially, and disperse using ultrasound for 1 hour to obtain a mixed solution. Slowly add 60 parts of the above-mentioned water dispersion containing pigment to the mixed solution, and stir continuously at a speed of 500 rpm until homogeneous. Then, process it 30 times under a pressure of 900 bar using a high-pressure homogenizer to obtain the finished water-based ink, which should be stored away from light.
[0085] No surfactants were added during the preparation of the aqueous dispersion in this comparative example, and no leveling agents or wetting agents were used in the finished ink. The ink exhibits poor wettability on low surface energy media, and the contact angle of the prepared ink is as follows: Figure 12 As shown, the contact angle is 62.9°, resulting in uneven ink droplet spread and a mottled image after printing. Furthermore, the inkjet printing effect of the prepared ink is as follows... Figure 13 As shown, it can be clearly seen that due to the lack of stabilizing effect of surfactant, ink breaks occur during continuous printing in the thermal foaming process.
[0086] The fineness and adhesion of the inks prepared in the embodiments and comparative examples of this invention were tested. The fineness of the prepared inks was tested according to the national standard GB / T 13217.3-2022 "Ink Fineness Test Method". Adhesion was evaluated using the cross-cut adhesion test according to the national standard GB / T 9286-2021, and the ink layer peeling after tape removal was rated (0 being the best and 5 being the worst). The test results are shown in the table below.
[0087]
[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, they should all be considered to be within the protection scope of the present invention.
Claims
1. A method for preparing a heat-foamed water-based ink, characterized by, The method comprises the following steps: S1, adding an organic solvent to the polymer, stirring until completely dissolved, then adding an alkaline aqueous solution and deionized water to form a uniform emulsion under high-speed stirring; S2, adding pigments and a first surfactant under high-speed stirring, and then transferring the mixture to a high-pressure homogenizer tank for circulation and dispersion to obtain a dispersion liquid; the obtained dispersion liquid is distilled under reduced pressure until no odor of the organic solvent and the alkaline solvent is detected, to obtain a water dispersion with pigments; S3, mixing a water-soluble organic solvent, a second surfactant and deionized water, and uniformly dispersing the mixture by ultrasonic dispersion to obtain a mixed solution; slowly adding the water dispersion with pigments into the mixed solution, uniformly stirring and then treating the mixture with a high-pressure homogenizer to obtain a water-based ink product, which is stored in the dark.
2. The method for preparing thermally foamed water-based ink according to claim 1, characterized in that, According to the weight parts, the polymer is 15-65 parts, the organic solvent is 40-100 parts, the alkaline aqueous solution is 10-50 parts, the deionized water is 150-600 parts, the pigments are 20-80 parts, the first surfactant is 1-20 parts, the water-soluble organic solvent is 0.5-10 parts, and the second surfactant is 1-20 parts; the amount of deionized water added in step S1 is 100-400 parts.
3. The method of claim 1, wherein the water-based ink is prepared by heating and foaming. In step S1, the polymer is a water-based resin, specifically one of a polyacrylic resin, a polyurethane resin and an epoxy resin, and the resin has a molecular weight of 10,000-200,000; The organic solvent is an alcohol solvent, a ketone solvent or an ether solvent, specifically one of acetone, methyl ethyl ketone, methyl isobutyl ketone, ethanol, isopropyl alcohol, dibutyl ether, tetrahydrofuran and dioxane; The base of the alkaline aqueous solution is one of lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine and triethylamine, and the alkaline aqueous solution has a mass concentration of 10-20%.
4. The method of claim 1, wherein the water-based ink is prepared by heating and foaming. In step S1, the stirring speed is 300-1,000 rap / min, and the high-speed stirring speed is 1,000-5,000 rap / min.
5. The method of claim 1, wherein the water-based ink is foamed by heating. In step S2, the pigments are organic pigments or inorganic pigments, the organic pigments are one of azo pigments, diazo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, perylene pigments and anthraquinone pigments, and the inorganic pigments are one of furnace black, acetylene black, carbon black, metal oxides and metal chlorides; The first surfactant is one of wetting agents, dispersants, viscosity regulators, defoaming agents, leveling agents and brightening agents.
6. The method of claim 1, wherein the water-based ink is foamed by heating. In step S2, the high-speed stirring speed is 4,000-10,000 rap / min, the high-speed shearing dispersion time is 30-90 min, the pressure of the high-pressure homogenizer is 800-1,800 bar, the homogenization cycle number is 15-25, and the temperature of the reduced-pressure distillation is 25-85℃.
7. The method of claim 1, wherein the water-based ink is foamed by heating. In step S3, the water-soluble organic solvent is one of ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerol, trimethylolpropane and diethylene glycol diethyl ether; The second surfactant is one of wetting agents, dispersants, viscosity regulators, defoaming agents, leveling agents and brightening agents.
8. The method of claim 1, wherein the water-based ink is foamed by heat. Step S3, ultrasonic time is 0.5-2.5 h, stirring speed of uniform dissolution is 300-1000 rap / min, pressure of high-pressure homogenizer is 800-1800 bar, and homogenization cycle number is 5-50 times.
9. A heat-expandable aqueous ink prepared by the production method according to any one of claims 1 to 8.
10. A method of applying a heat-foamed aqueous ink according to claim 9, characterized in that, It is applied to a heat-expandable inkjet printer.