Water-based pigment ink for corrugated paper jet printing

Abstract

Water-based pigment ink for corrugated paper jet printing comprises a humectant, a surfactant, pigment paste, resin, a pH regulator and water, the resin comprises main resin and additional resin, the weight percentage of the pigment paste to the resin is (40%-50%): (5%-12%), the main resin comprises waterborne polyurethane resin, and the additional resin comprises acrylic resin. According to the water-based pigment ink for corrugated paper jet printing, the compatibility between the pigment paste and the resin is good, and the whole water-based pigment ink has good standby performance and high color saturation during ink-jet printing on the corrugated paper.

Description

Technical Field

[0001] This invention relates to the field of water-based pigment inks, and more particularly to water-based pigment inks for printing on corrugated paper. Background Technology

[0002] Driven by the booming development of e-commerce, the market demand for corrugated paper packaging is also growing stronger.

[0003] Corrugated paper packaging uses dark yellow or grayish-brown corrugated paper with a relatively rough surface. When inkjet printing on corrugated paper, water-based inks such as dye-based inks and pigment-based inks are mainly used. In related technologies, when using pigment-based inks on corrugated paper, color saturation is low and color development is poor. During idle or suction-heating idle processes, the pigment in the nozzle connected to the pigment ink remains suspended in the printhead for a certain period. Some of the water in the pigment ink evaporates, causing it to dry out, resulting in poor idle performance and reduced suction-heating idle performance. This makes the remaining components in the pigment ink, especially the pigment particles, prone to aggregation, precipitation, and coagulation into hard lumps, clogging the nozzles. Consequently, subsequent inkjet printing from clogged nozzles results in even worse color development and more prone to deviations in the printed pattern. Furthermore, frequent cleaning of clogged nozzles increases maintenance costs. Summary of the Invention

[0004] In view of this, the present invention proposes a water-based pigment ink for corrugated paper printing, which aims to achieve high color saturation while improving the standby performance of water-based pigment ink.

[0005] The water-based pigment ink for corrugated paper printing proposed in this invention comprises: a humectant, a surfactant, a pigment paste, a resin, a pH adjuster, and water. The resin includes a main resin and an auxiliary resin. The weight percentage of the pigment paste and the resin is 40%~50%:5%~12%. The main resin includes water-based polyurethane resin, and the auxiliary resin includes acrylic resin.

[0006] As can be seen from the above technical solution, the water-based pigment ink for corrugated paper printing proposed in this invention, by using the aforementioned types of resins and appropriately proportioned pigment pastes and resins, improves the compatibility between pigment pastes and resins. Under the presence of humectants, surfactants, and pH adjusters, acrylic resins, after the moisture is reduced or completely evaporated, can exist in a discrete, powdery, or granular form. During a certain standby time, this can prevent pigment particle aggregation, slow down the pigment flocculation process, and prevent nozzle clogging. Because the water-based polyurethane resin can be adsorbed onto the surface of pigment paste particles, even after the water-based pigment ink is concentrated and its concentration increases during standby, the pigment paste particles can be well maintained in a certain position. This effectively prevents flocculation between pigment particles, thus giving water-based pigment inks better standby performance. During the inkjet process, acrylic resins can quickly form a discontinuous film, reducing the rate at which pigment particles penetrate into the corrugated paper. Water-based polyurethane resins can form a soft, continuous, and dense film on the surface of the corrugated paper, combining with more unpenetrated pigment particles and fixing them to the surface of the corrugated paper, forming a more stable pigment layer. As the first interface light interacts with, the pigment layer produces very rich and vibrant colors, increasing the color density of the water-based pigment ink printed on the corrugated paper, and thus enhancing the color saturation of the water-based pigment ink printed on the corrugated paper.

[0007] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the disclosure of the embodiments of the present invention. Attached Figure Description

[0008] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0009] Figure 1a This is a test print image of the water-based pigment ink of Embodiment 1 of the present invention before it is suspended in standby mode. Figure 1b This is a test print image of the water-based pigment ink from Embodiment 1 of the present invention after it has been suspended in standby mode. Figure 2a This is a test print image of the water-based pigment ink in Embodiment 2 of the present invention before it is suspended in standby mode. Figure 2b This is a test print image of the water-based pigment ink of Embodiment 2 of the present invention after being suspended in standby mode; Figure 3a This is a test print image of the water-based pigment ink in Embodiment 3 of the present invention before it is suspended in standby mode. Figure 3b This is a test print image of the water-based pigment ink of Embodiment 3 of the present invention after being suspended in standby mode; Figure 4a This is a test print image of the water-based pigment ink in Embodiment 4 of the present invention before it is suspended in standby mode. Figure 4b This is a test print image of the water-based pigment ink in Embodiment 4 of the present invention after being suspended in standby mode; Figure 5 This is a color gradation diagram of the water-based pigment ink of Embodiment 1 of the present invention; Figure 6 This is a color gradation diagram of the water-based pigment ink of Embodiment 2 of the present invention; Figure 7 This is a color gradation diagram of the water-based pigment ink of Embodiment 3 of the present invention; Figure 8 This is a color gradation diagram of the water-based pigment ink of Embodiment 4 of the present invention; Figure 9 This is a schematic diagram of the preparation steps of water-based pigment ink for corrugated paper printing according to some embodiments of the present invention. Detailed Implementation

[0010] 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, not all, of the embodiments of the present invention. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0011] Unless otherwise specified, the following embodiments and features can be combined with each other. Unless otherwise stated, all reagents and raw materials are commercially available.

[0012] Corrugated paper has a dark color and a rough surface. Water-based inks used for inkjet printing on corrugated paper are divided into dye inks and pigment inks. Although dye inks have the advantages of bright colors and high color saturation, they are not waterproof, not lightfast, and are prone to fading and abrasion. When dye inks are used to print on corrugated paper, if the corrugated paper gets damp or wet, the pattern will smudge and become blurred. This limits the application scenarios of dye inks on corrugated paper, making them only suitable for indoor, short-term, and dry environments for corrugated paper packaging or displays, such as indoor booths for short-term events or indoor decorations that do not require transportation.

[0013] Pigment inks contain pigment particles that adhere to the surface of paper fibers, offering superior water resistance, lightfastness (especially resistance to UV fading), and abrasion resistance compared to dye inks. However, the color saturation of the resulting pattern printed on corrugated paper is typically lower. Furthermore, pigment inks used for printing on corrugated paper generally have poor standby performance. The pigments in pigment inks are nanoscale solid particles suspended in water by a dispersant, forming a "colloid" or "suspension." Once the water evaporates, these solid particles aggregate, precipitate, and solidify into hard lumps, firmly clogging the fine nozzles. This leads to uneven spraying, inconsistent coloring, and a blurred appearance when printing on corrugated paper, significantly reducing the ink's standby performance. Frequent nozzle cleaning also greatly increases maintenance costs.

[0014] In view of this, this application proposes a water-based pigment ink for corrugated paper inkjet printing. By selecting appropriate resins and pigment pastes, excellent color saturation can be achieved. The synergistic effect of the various components can also achieve excellent standby performance of the water-based pigment ink, thereby meeting the urgent needs of the corrugated paper inkjet printing market.

[0015] The water-based pigment ink for corrugated paper printing according to this application includes: a humectant, a surfactant, a pigment paste, a resin, a pH adjuster, and water, wherein the resin includes a main resin and an auxiliary resin, and the weight percentage of the pigment paste and the resin is 40%~50%:5%~12%, the main resin includes water-based polyurethane resin, and the auxiliary resin includes acrylic resin.

[0016] It should be noted that the weight percentage of pigment paste and resin in this application is 40%~50%:5%~12%, for example, the weight percentage includes values ​​such as 40%:5%, 43%:7%, 45%:8%, 49%:10%, 50%:12%, etc., as well as the range defined by any two of these specific ratios. As long as it is within the above ratio range, it conforms to the pigment paste and resin ratio of this application. It should be noted that the weight percentage in this application is the percentage of each component by weight of the entire water-based pigment ink. The weight percentage of each substance in this application can correspond to the weight ratio of each substance.

[0017] In this application, water dissolves other components and gives the water-based pigment ink good fluidity; the humectant has good hygroscopic properties, allowing the water in the ink to evaporate more slowly, thus maintaining good fluidity and wettability for a certain standby time; the surfactant forces the pigment paste particles to disperse more evenly, improving the anti-flocculation and physical stability of the water-based pigment ink; the surfactant also helps the water-based pigment ink spread quickly on the corrugated paper surface; the pH adjuster can adjust the pH range of the water-based pigment ink, for example, to be weakly alkaline, which is beneficial for each component to function better, has better compatibility, and also has a certain antibacterial effect; the selection of pigment paste can provide the required inkjet color and provide basic hues; the selection of resin can provide a certain adhesion matrix for the pigment paste, improving the adhesion of pigment paste particles on corrugated paper; it can also maintain a certain distance between pigment paste particles to prevent large agglomeration.

[0018] As can be seen from the above, the water-based pigment ink for corrugated paper printing proposed in this invention improves the compatibility between pigment paste and resin by using the above-mentioned acrylic resin and water-based polyurethane resin, as well as pigment paste and resin in appropriate proportions. This makes the water-based pigment ink less prone to agglomeration and clumping, and maintains a certain degree of dispersion performance and system uniformity.

[0019] In the presence of humectants, surfactants, and pH adjusters, acrylic resins, after significant moisture reduction or evaporation, can exist in discrete, powdery, or granular forms. During a certain standby time, acrylic resins act as a physical barrier, preventing direct contact or aggregation of pigment particles, slowing down pigment flocculation, preventing nozzle clogging, and making water-based pigment inks more stable. Water-based polyurethane resins, because they can adsorb onto the surface of pigment particles, can maintain pigment particles in a relatively good position even after the water-based pigment ink has concentrated and increased in concentration during standby, effectively preventing flocculation between pigment particles, thus giving water-based pigment inks good standby performance. (For reference) Figures 1a to 4b As shown, the water-based pigment ink of this application showed little change in the printed test images before and after suspension standby and before and after suction heating standby, and no phenomena such as slanted spraying or blurring occurred.

[0020] During the inkjet printing process, acrylic resins can quickly form a discontinuous film, thus reducing the rate at which pigment particles penetrate into the corrugated paper. Waterborne polyurethane resins, on the other hand, can form a soft, continuous, and dense film on the surface of the corrugated paper, combining with more unpenetrated pigment particles and fixing them to the surface, forming a smooth, continuous composite layer of pigment and resin, thus creating a stable pigment layer. Because waterborne polyurethane resins typically have high transparency, they have minimal impact on the color development of the pigment layer. As the first interface for light, the pigment layer exhibits very rich and vibrant colors, increasing the color density of the waterborne pigment ink printed onto the corrugated paper, thereby enhancing the color saturation. (See reference...) Figures 5 to 8 By observing the color gradation diagram, the water-based pigment ink of this application has a high color saturation, and the color is bright and saturated after inkjet printing on corrugated paper.

[0021] Therefore, the water-based pigment ink for corrugated paper printing in this application can achieve both good suspension standby performance / suction heating standby performance and good color saturation.

[0022] In some embodiments of this application, the pigment paste includes carbon black, phthalocyanine blue 15:3, pigment yellow 74, or pigment red 254; and / or, in some embodiments of this application, the pigment paste includes nanoscale particles of pigment. The four different colored pigment pastes listed in these embodiments are all beneficial for maximizing the pure reflection of light at a specific wavelength and minimizing all unnecessary light interference, such as reducing scattering, absorption, and transmission at a specific wavelength.

[0023] When carbon black is used in the embodiments, the blackness of the color can be improved. This color has extremely strong absorption of light across various wavelengths, appearing visually as black. For example, in specific embodiments, the carbon black uses powder particles with a particle size of less than 30nm, such as 10nm~25nm, including values ​​of 10nm, 12nm, 14nm, 17nm, 20nm, 22nm, and 25nm, etc., and achieves good dispersion under the action of surface dispersants and resins, effectively improving the color saturation of water-based pigment inks containing carbon black after inkjet printing on corrugated paper.

[0024] In the examples, when Phthalocyanine Blue 15:3, Pigment Yellow 74, or Pigment Red 254 are used, the absorption band is narrower, and the reflection band is either sharp, steep, or highly efficient. Compared to other pigment pastes, they can achieve higher color saturation within their respective color thresholds. To further improve the color saturation of these pigment pastes, the particle size of the pigment can be controlled to be less than 150 nm. For example, in specific embodiments, the particle size is controlled to be 70 nm to 130 nm, including values ​​such as 70 nm, 80 nm, 87 nm, 90 nm, 100 nm, 110 nm, 115 nm, 120 nm, 126 nm, 130 nm, 140 nm, and 150 nm. This provides a foundation for achieving higher color saturation while ensuring good dispersibility.

[0025] In some embodiments of this application, the weight percentage of the main resin and the auxiliary resin is 70%~90%:10%~30%, including values ​​such as 70%:30%, 80%:20%, 85%:15%, 90%:10%, and the range defined by any two of the aforementioned ratios. Here, the weight percentage of the main resin and the auxiliary resin corresponds to a weight ratio of 7~9:1~3. By controlling the ratio of main resin and auxiliary resin, the compatibility between the resin and pigment paste is good. This allows the water-based pigment ink to prevent direct contact between pigment paste particles during standby, instead dispersing them as much as possible and maintaining a certain distance. This ensures the water-based pigment paste maintains a certain level of wettability and flexibility, reducing potential drying and clogging in the nozzle, thus improving the standby performance of the water-based pigment ink in this embodiment. Furthermore, during inkjet printing, the water-based pigment ink reduces the penetration of pigment paste into the corrugated paper. The main resin tightly encapsulates, wraps around, and fixes the pigment paste particles, forming a smooth, continuous, and firm film layer on the surface of the corrugated paper. This allows the pigment paste particles to be fixed on the surface of the corrugated paper with good adhesion, forming a pigment layer with high color saturation. The main resin in this application also improves the abrasion resistance and adhesion of the pigment layer.

[0026] In some embodiments, the primary resin is at least one of Diamond D369, Esacote PU470, Esacote PU40, Stahl PU645, and Tianjin Atoz L302; in some embodiments, the secondary resin is at least one of Joncryl 3025, Joncryl 7601, Joncryl 8055, and Joncryl 1980. Diamond D369 provides good flexibility and abrasion resistance for water-based pigment inks, resulting in good flexibility during printing on corrugated paper, and producing abrasion- and scratch-resistant printed patterns, while also improving gloss. Esacote PU470 can quickly dry and fix the pigment paste on the surface of corrugated paper, reducing ink penetration into the corrugated paper and effectively improving color saturation and gloss of inkjet printing on corrugated paper. Water-based pigment inks containing Esacote PU40 significantly reduce nozzle clogging during inkjet printing on corrugated paper, facilitating the rapid redissolution of some water-based pigment ink on the nozzle surface when inkjet printing restarts. Water-based pigment inks containing Stahl PU645 exhibit superior scratch and abrasion resistance after inkjet printing on corrugated paper. Tianjin Atoz L302 provides water-based pigment inks with better flexibility, gloss, and adhesion, which helps reduce manufacturing costs. Adding Joncryl 3025 to water-based pigment inks results in more uniform pigment particle dispersion, less flocculation, and higher ink system stability. Both Joncryl 7601 and Joncryl 1980 dry quickly after being sprayed onto corrugated paper, effectively preventing excessive pigment penetration into the paper and ensuring more pigment particles remain on the surface, thus improving color saturation. The addition of Joncryl 8055 and Joncryl 1980 further enhances the adhesion and abrasion resistance of water-based pigment inks on corrugated paper.

[0027] In some further embodiments, the weight ratio of the main resin and the auxiliary resin of this application is 7~8.5:1.5~3, the main resin is Esacote PU470, Tianjin Atoz L302, Esacote PU40, Diamond D369 or Stahl PU645, and the auxiliary resin is Joncryl7601. For example, in specific embodiments, the weight ratio of the main resin Esacote PU470 to the auxiliary resin Joncryl 7601 is 8.5:1.5; another example is the weight ratio of the main resin Tianjin Atoz L302 to the auxiliary resin Joncryl 7601, which is 7:3; yet another example is the weight ratio of the main resin Esacote PU40 to the auxiliary resin Joncryl 7601, which is 8:2; the weight ratio of the main resin Esacote PU40, Esacote PU470, and the auxiliary resin Joncryl 7601 is 2:6:2 (that is, the weight ratio of the main resin to the auxiliary resin is 8:2); the weight ratio of the main resin Diamond D369 to the auxiliary resin Joncryl 7601 is 8.5:1.5; the weight ratio of the main resin Stahl PU645 to the auxiliary resin Joncryl 7601 is 8:2, etc.

[0028] In some embodiments, the weight percentage of humectant and surfactant is 30% to 40%: 1% to 3%, for example, the ratio includes 30%: 2%, 30%: 1%, 32%: 1.5%, 36%: 2%, 37%: 2.1%, 38%: 2.5%, 40%: 3%, 40%: 1%, etc., as well as range values ​​between any two of the aforementioned specific ratios. In these embodiments, by optimizing the ratio of humectant and surfactant, the hygroscopicity of the humectant can effectively reduce the evaporation of water in the water-based pigment ink; the surfactant can effectively reduce the surface tension of the pigment paste particles by utilizing electrostatic repulsion and steric hindrance effects, thereby reducing the retraction of the water-based pigment ink in the nozzle. Choosing an appropriate ratio of humectant and surfactant can make the water-based pigment ink more stable and more evenly distributed. Combined with the appropriate ratio of pigment paste and resin in the aforementioned embodiments, the water-based pigment inks in these embodiments have good standby performance, reducing the labor and time costs required for nozzle maintenance. Using an appropriate ratio of humectant and surfactant can promote the uniform suspension of pigment paste in the solution, preventing large-scale aggregation, significantly improving the anti-flocculation and physical stability of the water-based pigment ink, and ensuring that the pigment paste particles maintain a nanoscale dispersion state for a long time. At the same time, it can also achieve appropriate speed and uniform spreading of the water-based pigment ink during inkjet printing on corrugated paper surfaces. In some further embodiments, the weight percentage of humectant and surfactant is 36% to 40%: 2.1% to 3%, for example, the ratio includes values ​​such as 36%: 2.1%, 37%: 2.2%, 39%: 2.4%, 40%: 3%, and range values ​​between any two of the aforementioned specific ratios.

[0029] In some embodiments, the humectant includes polyol humectants or polyol ether humectants. These types of humectants provide excellent moisturizing properties and have strong hygroscopicity, which helps to retain moisture in the water-based pigment ink, keeping the entire water-based pigment ink in a relatively moist state during standby, preventing excessive evaporation of moisture, and thus improving the standby performance of the water-based pigment ink. In some specific embodiments, the humectant is selected from at least one of ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-hexanediol, 1,6-hexanediol, glycerol, 1,5-pentanediol, ethylene glycol ethyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol n-propyl ether, propylene glycol butyl ether, dipropylene glycol methyl ether, and polyethylene glycol with an average molecular weight of 200, 400, 600, 900, or 1000. For example, 1,4-butanediol and dipropylene glycol methyl ether have high boiling points and low saturated vapor pressures. In standby mode, water-based pigment inks containing 1,4-butanediol and / or dipropylene glycol methyl ether will have their ink water evaporate first at the nozzle orifice. At this time, these high-boiling-point co-solvents, due to their non-volatile properties, will remain more in the nozzle, allowing the water to be retained. They can also replace some of the evaporated water, maintaining a humid environment for the water-based pigment ink within the nozzle and preventing the ink from drying and curing too quickly due to water loss. For example, water-based pigment inks with added propylene glycol methyl ether not only have moisturizing properties but also achieve the advantage of rapid drying when sprayed onto corrugated paper. For example, 1,2-hexanediol not only has certain moisturizing properties but also certain hydrophobic properties, which can improve the ink's anti-permeability. It can synergistically work with the acrylic resins in the aforementioned embodiments to enhance the color saturation of the pigment particles during inkjet printing on the corrugated paper surface. In some specific embodiments, the humectant is selected from a combination of ethylene glycol, diethylene glycol, 1,2-propanediol, and 1,3-propanediol; or, the humectant is selected from a combination of glycerol, propylene glycol butyl ether, 1,4-butanediol, and 1,2-hexanediol; or, the humectant is selected from a combination of dipropylene glycol methyl ether, 1,6-hexanediol, glycerol, 1,5-pentanediol, and ethylene glycol ethyl ether; or the humectant is selected from a combination of 1,4-butanediol, 1,2-hexanediol, 1,6-hexanediol, ethylene glycol ethyl ether, and polyethylene glycol with an average molecular weight of 200 and 400.

[0030] In some embodiments, the surfactant includes acetylenic diol surfactants. Acetylene diol surfactants have high wetting and defoaming properties, which can simplify formulation.

[0031] In some further embodiments, the surfactant is selected from at least one of Surfynol DF-110BC, Surfynol CT-136, Surfynol 465, Surfynol 104E, Tego410, Dynol 607, and Rhodoline Df 4226. Surfynol DF-110BC, Surfynol CT-136, Surfynol 465, Surfynol 104E, Dynol 607, and Rhodoline Df 4226 are all acetylenic diol surfactants. Tego410 is a polyether siloxane surfactant. For example, Tego410, also known as Evonik Tego Wet 410, can significantly reduce the surface tension of the system, and its addition to water-based pigment inks can improve spreadability on corrugated paper surfaces. For example, Surfynol DF-110BC and Rhodoline DF 4226 provide efficient wetting while effectively suppressing foam formation, which is beneficial for improving the standby performance of water-based pigment inks. For instance, in some embodiments, Surfynol CT-136 and Surfynol 465 are used in combination as surfactants; or Dynol 960 and Tego 410 are used in combination as surfactants; or Surfynol DF-110BC, Dynol 607, and Dynol 960 are used in combination as surfactants; or Surfynol CT-136, Surfynol 465, and Surfynol 104E are used in combination as surfactants.

[0032] In some embodiments of this application, the weight percentage of pH adjuster to pigment paste is 0.5%~1%:40%~50%, for example, ratios include 0.5%:40%, 0.6%:42%, 0.7%:45%, and 1%:50%; and / or, the pH adjuster includes triethanolamine. By adjusting the proportion of pH adjuster in the water-based pigment ink and its weight percentage to pigment paste, the entire system can be made weakly alkaline while the resin, pigment paste, and surfactant can each play their respective roles. The particles generate charges on their surfaces, resulting in mutual repulsion, which is beneficial for improving the stability of the entire ink system, the particle dispersion of the pigment paste, and the color uniformity. This is beneficial for improving the standby performance of the water-based pigment ink and also for improving the color saturation, making the colors more vibrant. In some specific embodiments, the pH value of the water-based pigment ink is adjusted to 7~9 by the pH adjuster, for example, pH values ​​include 7, 7.5, 7.9, 8, 8.1, 8.2, 8.4, 8.5, and 9. In a more specific embodiment, the pH value of the water-based pigment ink is adjusted to 7.5-8.5 by adjusting the amount of pH adjuster added, for example, pH values ​​include 7.5, 7.9, 8, 8.1, 8.2, 8.4 and 8.5.

[0033] In some embodiments of this application, the viscosity of the water-based pigment ink is 10.01 mPa·s to 11.34 mPa·s at 30°C, for example, viscosity values ​​include 10.01 mPa·s, 10.05 mPa·s, 10.1 mPa·s, 10.2 mPa·s, 10.24 mPa·s, 10.4 mPa·s, 10.50 mPa·s, 10.52 mPa·s, 10.62 mPa·s, and 10.72 mPa·s. The values ​​of 10.75 mPa·s, 10.78 mPa·s, 10.81 mPa·s, 10.88 mPa·s, 10.96 mPa·s, 11.10 mPa·s, 11.21 mPa·s and 11.34 mPa·s, as well as the range of values ​​between any two of the aforementioned specific values, give the water-based pigment ink of this application good fluidity, which is beneficial for uniform ink output and smooth printing during the inkjet printing process on corrugated paper.

[0034] In some embodiments of this application, the surface tension of the water-based pigment ink is 24.7 mN / m to 28.0 mN / m. For example, the surface tension includes values ​​such as 24.7 mN / m, 25.1 mN / m, 25.5 mN / m, 26.2 mN / m, 26.5 mN / m, 26.7 mN / m, 27.3 mN / m, 27.5 mN / m, and 28.0 mN / m, as well as a range of values ​​between any two of the aforementioned specific values. This is beneficial for the water-based pigment ink to spread on corrugated paper and for the inkjet pattern to have good color saturation.

[0035] The preparation method of the water-based pigment ink for corrugated paper inkjet printing according to the foregoing embodiments of this application will be described below.

[0036] A method for preparing a water-based pigment ink for corrugated paper printing, wherein the weight percentages of each component in the water-based pigment ink are as follows: water 1%~5%, humectant 30%~40%, surfactant 1%~3%, pH adjuster 0.5%~1%, pigment paste 40%~50%, and resin 5%~12%. The functions, interrelationships, and proportions of each component have been described in the foregoing embodiments and will not be repeated here. It should be noted that the proportions of the aforementioned components in this application are weight percentages relative to the entire water-based pigment ink, that is, based on the weight of the entire water-based pigment ink being 100%, and the weight percentages of other components relative to the water-based pigment ink.

[0037] like Figure 9 As shown, the preparation method of water-based pigment ink for corrugated paper printing includes the following steps: first, water, humectant, surfactant and pH adjuster are added to a container according to the weight ratio; then, pigment paste and resin are added to the container according to the weight ratio; after stirring, the mixture is filtered and defoamed to obtain water-based pigment ink.

[0038] As can be seen from the above, in the preparation method of the water-based pigment ink for corrugated paper inkjet printing proposed in the aforementioned embodiments of this application, water, humectant, surfactant, and pH adjuster are added to the container first. The compatibility among the four components is good, and a better dissolution and protection environment is provided for the easily aggregated pigment paste and the easily film-forming resin, that is, a better charge-stable environment is provided, such as a weakly alkaline environment. The surfactant added to the system first can provide a rapid dispersing force for the pigment paste added later. After the resin is added, it is not easy to demulsify. Thus, good compatibility among the components can be achieved, the overall water-based pigment ink has good dispersibility and high stability, and is not prone to flocculation. After stirring and defoaming, the water-based pigment ink material is more uniform, which is beneficial for inkjet printing using nozzles.

[0039] In some embodiments, the stirring speed can be controlled to be 300 rpm / min to 400 rpm / min. For example, the speed can include values ​​such as 300 rpm / min, 320 rpm / min, 350 rpm / min, 380 rpm / min and 400 rpm / min, so as to reduce the occurrence of flocculation while ensuring that the components are mixed evenly and dispersed uniformly.

[0040] In some embodiments, the stirring time is 30 min to 65 min, including values ​​such as 30 min, 40 min, 50 min, 55 min, 60 min and 65 min, so as to achieve uniform dispersion of the entire water-based pigment ink.

[0041] In some embodiments, in order to improve the dispersibility of the system and enhance the smoothness and stability of inkjet printing, the well-stirred mixture is typically filtered using a filter membrane with a pore size of 0.2 μm to 0.6 μm, such as pore sizes of 0.2 μm, 0.23 μm, 0.3 μm, 0.35 μm, 0.4 μm, 0.44 μm, 0.5 μm, 0.55 μm, and 0.6 μm, thereby filtering out potentially large-volume impurities and significant flocculents.

[0042] In some further embodiments, water, humectant, surfactant, pH adjuster, pigment paste and resin are added sequentially from front to back according to the aforementioned ratio. After stirring, mixing and filtering to remove bubbles, water-based pigment ink is obtained, thereby obtaining water-based pigment ink with stable properties and good dispersibility.

[0043] In other embodiments, the pH can be adjusted after the resin and pigment paste have been fully added, thereby achieving accurate formulation of the entire water-based pigment ink system.

[0044] The following describes the water-based pigment ink for corrugated paper printing and its preparation method with reference to specific embodiments.

[0045] Example 1 In Example 1, the water-based pigment ink for corrugated paper printing is a water-based black ink. The weight percentages of each component are as follows: 38% humectant, 1.5% surfactant, 5% resin, 50% pigment paste, 0.5% pH adjuster, and 5% water. The humectant is a blend of ethylene glycol, diethylene glycol, 1,2-propanediol, and 1,3-propanediol in a weight ratio of 4:2:2:1. The surfactant is a blend of Surfynol CT-136 and Surfynol 465 in a weight ratio of 5:5. The resin is a blend of Diamond D369 and Joncryl 1980 in a weight ratio of 8:2. The pigment paste is carbon black with a particle size of 20 nm. The adjuster is triethanolamine.

[0046] Prepare each component according to the above proportions, and add them to a container (such as a reaction tank) in the following order: water, humectant, surfactant, pH adjuster, pigment paste, and resin. Stir at a speed of less than 350 rpm / min for 40 min, then filter with a 0.45 μm filter membrane, and finally seal to remove bubbles to obtain the finished water-based pigment ink.

[0047] Example 2 In Example 2, the water-based pigment ink for corrugated paper printing is a water-based blue ink. The weight percentages of each component are as follows: 40% humectant, 2.3% surfactant, 9% resin, 43% pigment paste, 0.9% pH adjuster, and 4.8% water. The humectant is a blend of glycerol, propylene glycol butyl ether, 1,4-butanediol, and 1,2-hexanediol, with a weight ratio of 6:0.5:2:1.5. The surfactant is a blend of Dynol 960 and Tego 410, with a weight ratio of 6:4. The resin is Stahl PU645 and Joncryl 8055, with a weight ratio of 9:1. The pigment paste is phthalocyanine blue in a 15:3 ratio. The adjuster is triethanolamine.

[0048] Prepare each component according to the above proportions, and add them to a container (such as a reaction tank) in the following order: water, humectant, surfactant, pH adjuster, pigment paste, and resin. Stir at a speed of less than 350 rpm for 50 min, then filter with a 0.22 μm filter membrane, and finally seal to remove bubbles to obtain the finished water-based pigment ink.

[0049] Example 3 In Example 3, the water-based pigment ink for corrugated paper printing is a water-based red ink. The weight percentages of each component are as follows: 32.3% humectant, 2.1% surfactant, 12% resin, 50% pigment paste, 0.6% pH adjuster, and 3% water. The humectant is a compound of dipropylene glycol methyl ether, 1,6-hexanediol, glycerol, 1,5-pentanediol, and ethylene glycol ethyl ether, with a weight ratio of 0.5:2:3:4:0.5. The surfactant is a compound of Surfynol DF-110BC, Dynol 607, and Dynol 960, with a weight ratio of 3:3:4. The resin is Esacote PU470 and Joncryl 7601, with a weight ratio of 8.5:1.5. The pigment paste is Pigment Red 254. The adjuster is triethanolamine.

[0050] Prepare each component according to the above proportions, and add them to a container (such as a reaction tank) in the following order: water, humectant, surfactant, pH adjuster, pigment paste, and resin. Stir at a speed of less than 380 rpm / min for 60 min, then filter with a 0.6 μm filter membrane, and finally seal to remove bubbles to obtain the finished water-based pigment ink.

[0051] Example 4 In Example 4, the water-based pigment ink for corrugated paper printing is a water-based yellow ink. The weight percentages of each component are as follows: 36% humectant, 3% surfactant, 11% resin, 44% pigment paste, 1% pH adjuster, and 5% water. The humectant is a blend of 1,4-butanediol, 1,2-hexanediol, 1,6-hexanediol, ethylene glycol ethyl ether, and polyethylene glycol with average molecular weights of 200 and 400, in a weight ratio of 3:2:2:0.5:1. The surfactant is a blend of Surfynol CT-136, Surfynol 465, and Surfynol 104E, in a weight ratio of 3:4:3. The resin is a blend of Esacote PU470, Esacote PU40, and Joncryl 3025, in a weight ratio of 6:3:1. The pigment paste is Pigment Yellow 74. The pH adjuster is triethanolamine.

[0052] Prepare each component according to the above proportions, and add them to a container (such as a reaction tank) in the following order: water, humectant, surfactant, pH adjuster, pigment paste, and resin. Stir at a speed of less than 320 rpm / min for 65 min, then filter with a 0.22 μm filter membrane, and finally seal to remove bubbles to obtain the finished water-based pigment ink.

[0053] Example 5 In Example 5, the water-based pigment ink for corrugated paper printing is a water-based black ink. The weight percentages of each component are as follows: 37% humectant, 2.5% surfactant, 9% resin, 46% pigment paste, 0.5% pH adjuster, and 5% water. The humectant is a blend of glycerol, propylene glycol methyl ether, 1,2-propanediol, and 1,5-pentanediol in a weight ratio of 4:3:5:2. The surfactant is a blend of Surfynol CT-136 and Dynol 607 in a weight ratio of 2:1. The resin is a blend of Tianjin Atoz L302 and Joncryl 7601 in a weight ratio of 7:3. The pigment paste is carbon black with a particle size of 20 nm. The adjuster is triethanolamine.

[0054] Prepare each component according to the above proportions, and add them to a container (such as a reaction tank) in the following order: water, humectant, surfactant, pH adjuster, pigment paste, and resin. Stir at a speed of less than 350 rpm / min for 40 min, then filter with a 0.45 μm filter membrane, and finally seal to remove bubbles to obtain the finished water-based pigment ink.

[0055] Example 6 In Example 6, the water-based pigment ink for corrugated paper printing is a water-based black ink. The weight percentages of each component are as follows: 35.5% humectant, 2.2% surfactant, 10% resin, 47% pigment paste, 0.8% pH adjuster, and 4.5% water. The humectant is a blend of 1,2-propanediol, 1,6-hexanediol, propylene glycol n-propyl ether, and 1,3-propanediol, with a weight ratio of 6:1:4:3. The surfactant is a blend of Surfynol CT-136 and Surfynol DF-110BC, with a weight ratio of 4:1. The resin is a blend of Esacote PU40 and Joncryl 7601, with a weight ratio of 8:2. The pigment paste is carbon black with a particle size of 20 nm. The adjuster is triethanolamine.

[0056] Prepare each component according to the above proportions, and add them to a container (such as a reaction tank) in the following order: water, humectant, surfactant, pH adjuster, pigment paste, and resin. Stir at a speed of less than 350 rpm / min for 40 min, then filter with a 0.45 μm filter membrane, and finally seal to remove bubbles to obtain the finished water-based pigment ink.

[0057] Example 7 In Example 7, the water-based pigment ink for corrugated paper printing is a water-based blue ink. The weight percentages of each component are as follows: 35% humectant, 2.4% surfactant, 9.5% resin, 49% pigment paste, 0.9% pH adjuster, and 3.2% water. The humectant is a blend of glycerol, propylene glycol methyl ether, 1,2-hexanediol, and 1,5-pentanediol in a weight ratio of 5:5:1:1. The surfactant is a blend of Surfynol 465, Surfynol 104E, and Surfynol DF-110BC in a weight ratio of 5:1:1. The resin is a blend of Esacote PU40, Esacote PU470, and Joncryl 7601 in a weight ratio of 2:6:2. The pigment paste is phthalocyanine blue in a ratio of 15:3. The pH adjuster is triethanolamine.

[0058] Prepare each component according to the above proportions, and add them to a container (such as a reaction tank) in the following order: water, humectant, surfactant, pH adjuster, pigment paste, and resin. Stir at a speed of less than 350 rpm for 50 min, then filter with a 0.22 μm filter membrane, and finally seal to remove bubbles to obtain the finished water-based pigment ink.

[0059] Example 8 The formulation of Example 8 is similar to that of Example 3, except that the resin used is Diamond D369 and Joncryl7601, with a weight ratio of 8.5:1.5.

[0060] Example 9 The formulation of Example 9 is similar to that of Example 4, except that Stahl PU645 and Joncryl7601 resins are used, with a weight ratio of 8:2.

[0061] Comparative Example 1 The formulation and preparation method are largely the same as those of the water-based pigment ink in Example 4, except that Esacote PU470 and Esacote PU40 are used as resins, and the weight ratio of the two is 6:3, increasing the weight percentage of the two in the water-based pigment ink to 11%.

[0062] Prepare each component according to the proportions, and add them to a container (such as a reaction tank) in the following order: water, humectant, surfactant, pH adjuster, pigment paste, and resin. Stir at a speed of less than 350 rpm for 40 min, then filter with a 0.45 μm filter membrane, and finally seal to remove bubbles to obtain water-based pigment ink.

[0063] Comparative Example 2 The formulation and preparation method are largely the same as those of the water-based pigment ink in Example 1, except that only Diamond D369 resin is used, and the weight percentage of Diamond D369 in the water-based pigment ink is increased to 5%.

[0064] Prepare each component according to the proportions, and add them to a container (such as a reaction tank) in the following order: water, humectant, surfactant, pH adjuster, pigment paste, and resin. Stir at a speed of less than 350 rpm for 40 min, then filter with a 0.45 μm filter membrane, and finally seal to remove bubbles to obtain water-based pigment ink.

[0065] Comparative Example 3 The formulation and preparation method are largely the same as those of the water-based pigment ink in Example 1, except that only Joncryl 1980 resin is used, and its weight percentage in the water-based pigment ink is increased to 8%.

[0066] Prepare each component according to the proportions, and add them to a container (such as a reaction tank) in the following order: water, humectant, surfactant, pH adjuster, pigment paste, and resin. Stir at a speed of less than 350 rpm for 40 min, then filter with a 0.45 μm filter membrane, and finally seal to remove bubbles to obtain water-based pigment ink.

[0067] Comparative Example 4 The formulation and preparation method are largely the same as those of the water-based pigment ink in Example 1, except that the ratio of resin to pigment paste is 15%:38%, and the weight percentage of water in the water-based pigment ink is increased to 7%.

[0068] Prepare each component according to the proportions, and add them to a container (such as a reaction tank) in the following order: water, humectant, surfactant, pH adjuster, pigment paste, and resin. Stir at a speed of less than 350 rpm for 40 min, then filter with a 0.45 μm filter membrane, and finally seal to remove bubbles to obtain water-based pigment ink.

[0069] Comparative Example 5 The formulation and preparation method are largely the same as those of the water-based pigment ink in Example 1, except that the ratio of resin to pigment paste is 3%:55%, and the weight percentage of water in the water-based pigment ink is reduced to 2%.

[0070] Prepare each component according to the proportions, and add them to a container (such as a reaction tank) in the following order: water, humectant, surfactant, pH adjuster, pigment paste, and resin. Stir at a speed of less than 350 rpm for 40 min, then filter with a 0.45 μm filter membrane, and finally seal to remove bubbles to obtain water-based pigment ink.

[0071] Comparative Example 6 The formulation and preparation method are largely the same as those of the water-based pigment ink in Example 1, except that the weight percentage of humectant to surfactant is 26%:0.5%, and the weight percentage of water in the water-based pigment ink is increased to 18%.

[0072] Prepare each component according to the proportions, and add them to a container (such as a reaction tank) in the following order: water, humectant, surfactant, pH adjuster, pigment paste, and resin. Stir at a speed of less than 350 rpm for 40 min, then filter with a 0.45 μm filter membrane, and finally seal to remove bubbles to obtain water-based pigment ink.

[0073] Comparative Example 7 The formulation and preparation method are largely the same as those of the water-based pigment ink in Example 1, except that the weight percentage of humectant to surfactant is 41%:3.3%, and the weight percentage of water in the water-based pigment ink is reduced to 0.2%.

[0074] Prepare each component according to the proportions, and add them to a container (such as a reaction tank) in the following order: water, humectant, surfactant, pH adjuster, pigment paste, and resin. Stir at a speed of less than 350 rpm for 40 min, then filter with a 0.45 μm filter membrane, and finally seal to remove bubbles to obtain water-based pigment ink.

[0075] Comparative Example 8 The formulation and preparation method are largely the same as those of the water-based pigment ink in Example 3. The difference is that the weight percentage of pigment paste to resin is 25%:4%, and only Esacote PU470 resin is used, without the addition of Joncryl7601. The weight percentage of water in the water-based pigment ink is increased to 36%.

[0076] Prepare each component according to the above proportions, and add them to a container (such as a reaction tank) in the following order: water, humectant, surfactant, pH adjuster, pigment paste, and resin. Stir at a speed of less than 380 rpm / min for 60 min, then filter with a 0.6 μm filter membrane, and finally seal to remove bubbles to obtain water-based pigment ink.

[0077] Test case (a) Standby test of water-based pigment ink using Starlight SG600MA printhead 1. Print a test image after ink cleaning; 2. At a temperature of 25℃~30℃ and a humidity of 50%~60%, the device was suspended in standby mode for 24 hours. The printed test image was then tested. The printed test images before and after standby were observed. If the number of broken frames was less than 3 and there were no oblique or blurry prints, the device was considered qualified and rated A. If the number of broken frames was greater than 3 and oblique or blurry prints appeared, the device was considered unqualified and rated B. The results of the standby test for Examples 1~9 and Comparative Examples 1~8 are shown in Table 1.

[0078] 3. After 8 hours of standby with suction heating, the nozzle temperature is 35℃ and the humidity is 50%~60%. Test the printed test image after standby with suction heating. Observe the printed test images before and after standby. If the number of broken frames is less than 3 and there is no oblique spray or blurry print, it is qualified and rated A. If the number of broken frames is greater than 3 and oblique spray or blurry print appears, it is unqualified and rated B. The results of the suction heating standby test of Examples 1~9 and Comparative Examples 1~8 are shown in Table 1.

[0079] (ii) The color saturation of water-based pigment ink was tested using the Starlight SG600MA printhead.

[0080] 1. Print the water-based pigment inks of Examples 1-4 using color scale diagrams of 20%-100% to qualitatively observe the color saturation; 2. The color density of the water-based pigment inks in Examples 1-9 and the color density of the water-based pigment inks in Comparative Examples 1-8 were tested using a color density meter. The test results are shown in Table 1. (III) Viscosity test of water-based pigment inks The viscometer was used to test each example and comparative example at 30°C, and the test results are shown in Table 1.

[0081] (iv) Surface tension test of water-based pigment inks The surface tension tester was used to test each embodiment and comparative example, and the test results are shown in Table 1.

[0082] (v) pH test of water-based pigment inks A pH meter was used to test each example and comparative example, and the test results are shown in Table 1.

[0083] Table 1

[0084] Referring to Table 1, for the same color of water-based pigment ink, the viscosity of the embodiments of this application is lower than or at least comparable to that of the comparative example, indicating that the water-based pigment ink of this application has good flowability, which is beneficial for smooth inkjet printing. The surface tension and pH value of this application are within a suitable range, which is conducive to more uniform dispersion of the water-based pigment ink and also facilitates spreading on the surface of corrugated paper.

[0085] Combining the standby performance test results of suction heating and the standby performance test results of suspended air in Table 1, and Figures 1a to 4b The water-based pigment ink of this application embodiment showed no oblique spraying or blurring after standby testing. This indicates that the water-based pigment ink of this application embodiment has excellent suspension standby performance and excellent suction heating standby performance. It can maintain good wettability and fluidity during normal inkjet printing on corrugated paper or during long standby and active standby maintenance. It is not easy to clog the nozzle and can quickly recover in the next inkjet printing process without frequent nozzle cleaning, resulting in smooth inkjet printing.

[0086] Combining the color density test results in Table 1 and Figures 5 to 8 For water-based pigment inks of the same color, the color density of the water-based pigment ink of this application is at least equal to or higher than that of the comparative water-based pigment ink. Therefore, the water-based pigment ink of this application has high color saturation, bright colors, and uniform ink spraying when inkjet printed on corrugated paper, and can achieve better printing results in the process of inkjet printing on corrugated paper.

[0087] Therefore, the water-based pigment ink for corrugated paper printing provided in this application fully meets the color saturation requirements for corrugated paper printing. Furthermore, this water-based pigment ink also exhibits excellent standby performance and smooth printing operation. The water-based pigment ink prepared in this application reduces maintenance costs during printing while ensuring print quality.

[0088] By comparing the test results of Examples 1 and Comparative Examples 2-5, Examples 3 and Comparative Example 8, and Examples 4 and Comparative Example 1, it can be concluded that the water-based pigment ink of this application must simultaneously select water-based polyurethane resin and acrylic resin, and make appropriate ratios of the two resins. After the resin dries on the corrugated paper, it forms a smooth, slightly transparent film, which can improve the gloss and saturation of the color. The resulting water-based pigment ink can have both excellent standby performance and high color saturation.

[0089] By comparing the test results of Example 1 and Comparative Examples 6-7, it can be seen that the present application uses a humectant and a surfactant in a specific ratio, which can effectively slow down the evaporation of ink in the nozzle, thereby preventing the ink from drying and crystallizing, keeping the printhead moist, and improving the ink's standby performance.

[0090] In summary, the water-based pigment ink of this application embodiment, by adding various components and selecting the ratio of resin and pigment paste within a suitable range, can effectively improve the standby performance and color saturation of water-based pigment ink during inkjet printing, thereby effectively supporting the vigorous development of the corrugated paper packaging industry.

[0091] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A water-based pigment ink for printing on corrugated paper, characterized in that, include: The mixture comprises a humectant, a surfactant, a pigment paste, a resin, a pH adjuster, and water, wherein the resin includes a main resin and an auxiliary resin, and the weight percentage of the pigment paste and the resin is 40%~50%:5%~12%, wherein the main resin includes an aqueous polyurethane resin, and the auxiliary resin includes an acrylic resin.

2. The water-based pigment ink for corrugated paper printing as described in claim 1, characterized in that, The pigment paste includes carbon black, phthalocyanine blue 15:3, pigment yellow 74 or pigment red 254; and / or, the pigment paste includes colorants in nano-sized particles.

3. The water-based pigment ink for corrugated paper printing as described in claim 1, characterized in that, The weight percentage of the main resin and the auxiliary resin is 70%~90%: 10%~30%.

4. The water-based pigment ink for corrugated paper printing as described in claim 3, characterized in that, The primary resin is at least one of Diamond D369, Esacote PU470, Esacote PU40, Stahl PU645, and Tianjin Atoz L302; the secondary resin is at least one of Joncryl 3025, Joncryl 7601, Joncryl 8055, and Joncryl 1980.

5. The water-based pigment ink for corrugated paper printing as described in claim 4, characterized in that, The weight ratio of the main resin to the auxiliary resin is 7~8.5:1.5~3. The main resin is Esacote PU470, Tianjin Atoz L302, Esacote PU40, Diamond D369 or Stahl PU645, and the auxiliary resin is Joncryl7601.

6. The water-based pigment ink for corrugated paper printing as described in claim 1, characterized in that, The weight percentage of the humectant and the surfactant is 30%~40%:1%~3%.

7. The water-based pigment ink for corrugated paper printing as described in claim 6, characterized in that, The weight percentage of the humectant and the surfactant is 36%~40%:2.1%~3%; the humectant includes polyol humectants or polyol ether humectants; the surfactant includes alkynyldiol surfactants.

8. The water-based pigment ink for corrugated paper printing as described in claim 7, characterized in that, The humectant is selected from at least one of ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-hexanediol, 1,6-hexanediol, glycerol, 1,5-pentanediol, ethylene glycol ethyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol n-propyl ether, propylene glycol butyl ether, dipropylene glycol methyl ether, and polyethylene glycol with an average molecular weight of 200, 400, 600, 900, or 1000. The surfactant is selected from at least one of Surfynol DF-110BC, Surfynol CT-136, Surfynol 465, Surfynol 104E, Tego 410, Dynol 607, Dynol 604, Dynol 960, and Rhodoline Df 4226.

9. The water-based pigment ink for corrugated paper printing as described in claim 1, characterized in that, The pH adjuster has a weight percentage of 0.5%~1% to 40%~50% of the pigment paste; and / or the pH adjuster includes triethanolamine.

10. The water-based pigment ink for corrugated paper printing as described in any one of claims 1 to 9, characterized in that, The viscosity of the water-based pigment ink is 10.01 mPa·s to 11.34 mPa·s at 30°C; the surface tension of the water-based pigment ink is 24.7 mN / m to 28.0 mN / m; and the pH value of the water-based pigment ink is 7 to 9.

Images