Aqueous printing ink, process for its preparation and use thereof

Abstract

The application discloses a kind of water-based printing ink and its preparation method and application, belong to high polymer material technical field.The water-based printing ink provided by the application includes the following mass fraction of preparation raw materials: 5~20 parts of ethanol, 10~35 parts of water, 50~70 parts of water-based polyurethane emulsion, 0.2~0.5 parts of dispersing agent, 0.1~0.5 parts of defoaming agent, 1~5 parts of aluminum tripolyphosphate, 7~15 parts of pigment, 0.5~2 parts of ultraviolet absorber, 0.5~5 parts of antioxidant.The water-based polyurethane emulsion is used as main body resin in the application, and is matched with aluminum tripolyphosphate, ultraviolet absorber and antioxidant, and the water-based printing ink obtained has good weather resistance and adhesion, and the printed sample does not discolor for a long time, and has good durability.The water-based printing ink provided by the application has wide application in the field of gravure printing or flexographic printing.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and particularly relates to a water-based printing ink, its preparation method, and its application. Background Technology

[0002] Water-based inks are representative of environmentally friendly inks, meeting modern society's environmental protection requirements. Using water as the main solvent, they do not produce VOCs and cause less environmental pollution. Furthermore, water-based inks are more economical, with lower production costs, thus reducing overall production costs during the printing process. These advantages make environmentally friendly water-based inks widely applicable in the printing industry.

[0003] Currently, the performance of ordinary water-based inks on the market still needs improvement. Firstly, the adhesion of ordinary water-based inks is not as good as solvent-based inks, and their adhesion to some non-absorbent substrates (such as plastic films and BOPP films) is worse than that of solvent-based inks. Secondly, ordinary water-based inks have poor heat resistance; prolonged exposure to high outdoor temperatures may cause the ink layer to powder or crack. Finally, ordinary water-based inks also have poor weather resistance; prolonged exposure to sunlight may cause color changes or fading, affecting product performance and customer experience.

[0004] Therefore, it is necessary to find a water-based printing ink with good adhesion, heat resistance, and weather resistance. Summary of the Invention

[0005] In order to overcome the problems existing in the prior art, one of the objectives of the present invention is to provide a water-based printing ink, which has good adhesion, heat resistance and weather resistance.

[0006] The second objective of this invention is to provide a method for preparing the above-mentioned water-based printing ink.

[0007] The third objective of this invention is to provide an application of the above-mentioned water-based printing ink in the fields of gravure printing or flexographic printing.

[0008] The fourth objective of this invention is to provide a printed product obtained by printing with the above-mentioned water-based printing ink.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] The first aspect of the present invention provides an aqueous printing ink comprising the following raw materials in parts by weight: 5-20 parts ethanol, 10-35 parts water, 50-70 parts aqueous polyurethane emulsion, 0.2-0.5 parts dispersant, 0.1-0.5 parts defoamer, 1-5 parts aluminum tripolyphosphate, 7-15 parts pigment, 0.5-2 parts ultraviolet absorber, and 0.5-5 parts antioxidant.

[0011] In the water-based printing ink of this invention, water-based polyurethane emulsion is used as the main resin, combined with aluminum tripolyphosphate, ultraviolet absorbers, and antioxidants. This achieves good weather resistance and adhesion, and the printed samples do not change color after long-term use, demonstrating excellent performance. Specifically, aluminum tripolyphosphate is an inorganic salt with excellent hydrolytic stability, which can effectively improve the water resistance of the ink and enhance the interaction between pigments in the ink, thereby improving the ink's anti-blocking properties. Since the ink contains organic components, it is easily affected by oxygen and undergoes oxidation, leading to problems such as ink darkening and accelerated drying. Antioxidants can inhibit the occurrence of oxidation reactions, prevent ink oxidation and aging, delay the ink aging process, and maintain the stability and service life of the ink. Ultraviolet absorbers and other raw materials can effectively prevent fogging on the ink surface, thereby improving the ink's anti-fogging performance. The addition of ultraviolet absorbers and antioxidants can effectively inhibit the oxidation and flocculation of pigments in the ink, thereby improving the ink's storage stability.

[0012] Preferably, in the water-based printing ink, the water-based polyurethane emulsion is selected from anionic water-based polyurethane emulsions.

[0013] Preferably, the solid content of the water-based polyurethane emulsion in the water-based printing ink is 30-40 wt%; more preferably, it is 33-37 wt%.

[0014] Preferably, in the water-based printing ink, the pH value of the water-based polyurethane emulsion is 6-10; more preferably 7-9.

[0015] In a specific embodiment of the present invention, the waterborne polyurethane emulsion in the waterborne printing ink is selected from XH-FW358 waterborne polyurethane emulsion. XH-FW358 waterborne polyurethane emulsion is an anionic waterborne polyurethane emulsion, a white emulsion with a solid content of (35±2)wt% and a pH value of 7-9. It has good leveling properties, flexibility, and abrasion resistance, good water and anhydrous ethanol resistance, excellent film-forming properties, and good adhesion to plastic film substrates.

[0016] Preferably, the water-based polyurethane emulsion in the water-based printing ink comprises 52 to 68 parts by mass; more preferably, it comprises 55 to 65 parts by mass.

[0017] Preferably, in the water-based printing ink, the mass percentage of aluminum tripolyphosphate residue on a 500-mesh sieve is ≤1%;

[0018] Preferably, in the water-based printing ink, the mass percentage of the volatile matter of aluminum tripolyphosphate at 105°C is ≤1%.

[0019] In a specific embodiment of the present invention, the aluminum tripolyphosphate in the water-based printing ink includes at least one of A-ATW-1, A-ATW-3, A-ATW-11, or A-ATW-18; in a specific embodiment of the present invention, the aluminum tripolyphosphate is selected from A-ATW-1. A-ATW-1 has good thermal stability, acid resistance, water resistance, rust prevention, and corrosion resistance, and can protect the ink surface from the erosion of air and moisture, improving the weather resistance and durability of the ink.

[0020] Preferably, the aluminum tripolyphosphate in the water-based printing ink comprises 1.5 to 4.5 parts by mass; more preferably 2 to 4 parts.

[0021] Preferably, in the water-based printing ink, the ultraviolet absorber is selected from water-based ultraviolet absorbers.

[0022] In a specific embodiment of the present invention, the ultraviolet absorber in the water-based printing ink is selected from ZW-5 water-based ultraviolet absorber. ZW-5 water-based ultraviolet absorber is a light yellow transparent liquid with good compatibility and dispersibility with the ink of the present invention. Due to its unique structure, it has a highly efficient absorption and shielding effect on ultraviolet rays, with a UV blocking rate of ≥99% for 200-380nm, which can effectively improve the anti-aging ability of the ink layer, enhance weather resistance, and extend the service life of the ink layer.

[0023] Preferably, the ultraviolet absorber in the water-based printing ink comprises 0.6 to 1.5 parts by mass; more preferably 0.8 to 1.2 parts by mass.

[0024] Preferably, in the water-based printing ink, the antioxidant is selected from hindered phenolic antioxidants; more preferably, the antioxidant includes at least one of antioxidant 1010, antioxidant 1076, or antioxidant 264.

[0025] Antioxidant 1010 is a hindered phenolic antioxidant, chemically named pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid], which is a white crystalline powder. It is chemically stable and has good light stability and anti-color change properties. It is a highly efficient antioxidant that can effectively inhibit the oxidation reaction of the ink during processing and use, and maintain the stability and durability of the ink performance.

[0026] Antioxidant 1076 is a hindered phenolic antioxidant, chemically named β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate n-octadecyl alcohol ester. It is a white, odorless crystalline powder containing phenolic hydroxyl and amino groups. The phenolic hydroxyl group can donate hydrogen atoms to react with free radicals in the polymer material of the ink of this invention, thereby terminating the chain reaction of oxidation. At the same time, the amino group can capture free radicals and inhibit the oxidative degradation of the polymer material in the ink of this invention. It has good photostability, can absorb ultraviolet light, and prevent the material from undergoing photo-oxidation under light conditions, thereby maintaining the color and performance stability of the material.

[0027] Antioxidant 264 is a hindered phenolic antioxidant, chemically named 2,6-di-tert-butyl-4-methylphenol, a white crystalline or crystalline powder. It has antioxidant, anti-aging, and color-inhibiting effects, and can effectively inhibit the oxidation reaction of the ink of this invention, maintaining the color and performance stability of the ink.

[0028] Preferably, in the water-based printing ink, the antioxidant is used as one of the raw materials for preparing the water-based printing ink in the form of a solution.

[0029] Preferably, the solvent of the antioxidant solution is an alcohol solvent; more preferably, the alcohol solvent includes ethanol, isopropanol, or a combination thereof; even more preferably, the alcohol solvent is selected from a mixed solution of ethanol and isopropanol; more preferably, the alcohol solvent is selected from a mixed solution of ethanol and isopropanol in a mass ratio of (2-4):1.

[0030] Preferably, the antioxidant in the water-based printing ink is 1 to 4 parts by mass; more preferably 2 to 3 parts.

[0031] Preferably, in the water-based printing ink, the pigment includes at least one of yellow pigment, red pigment, blue pigment, black pigment, or green pigment.

[0032] In specific embodiments of the present invention, the pigments may be selected from the following types: white pigment can be purchased from Shandong Dongjia Group Co., Ltd., model: Titanium Dioxide SR-2377; yellow pigment can be purchased from Yuhong Pigment Co., Ltd., model: Permanent Yellow 2GS; red pigment can be purchased from Shandong Xuanyang New Material Co., Ltd., model: Permanent Red F2R; blue pigment can be purchased from Xingtai Caizhiyun Chemical Technology Co., Ltd., model: Phthalocyanine Blue B; black pigment can be purchased from Xingtai Caizhiyun Chemical Technology Co., Ltd., model: Pigment Carbon Black; green pigment can be purchased from Hebei Barunde Coatings Co., Ltd., model: Phthalocyanine Green G. It is understood that the above-mentioned pigment types are merely examples, and the pigment types of the present invention are not limited to the above types.

[0033] Preferably, in the water-based printing ink, the dispersant is selected from water-based dispersants.

[0034] In a specific embodiment of the present invention, the dispersant in the water-based printing ink includes at least one of BYK-180 water-based dispersant (Germany), BYK-199 water-based dispersant (Germany), TEGO-755W, TEGO-760W water-based dispersant, or Disponer W-18 water-based dispersant (Germany). These dispersants stabilize the liquid system, prevent sedimentation and stratification, and improve the flowability and drying speed of the ink of the present invention.

[0035] Preferably, in the water-based printing ink, the defoamer is selected from water-based defoamers.

[0036] In a specific embodiment of the present invention, the defoamer in the water-based printing ink includes at least one of the following: BYK-019 water-based defoamer (Germany), BYK-024 water-based defoamer (Germany), DAPRO AP 7015 water-based defoamer (Hemings Deqian), Tego Foamex 1488 water-based defoamer, or Tego Foamex 815N water-based defoamer. These defoamers effectively control foam formation in liquids, reduce the surface tension of the liquid, and hinder the process of gas accumulating in the liquid to form bubbles; they also adjust the surface tension of the liquid to meet the specific ink preparation process requirements of the present invention, improving the fluidity of the liquid and increasing production efficiency.

[0037] This invention uses water and ethanol as solvents, which can adjust the viscosity and drying speed of water-based printing inks.

[0038] Preferably, the water in the solvent is selected from deionized water.

[0039] Preferably, the water-based printing ink comprises the following raw materials in parts by weight: 5-20 parts ethanol, 10-35 parts water, 52-68 parts water-based polyurethane emulsion, 0.2-0.5 parts dispersant, 0.1-0.5 parts defoamer, 1.5-4.5 parts aluminum tripolyphosphate, 7-15 parts pigment, 0.6-1.5 parts ultraviolet absorber, and 1-4 parts antioxidant.

[0040] More preferably, the water-based printing ink comprises the following raw materials in parts by weight: 5-20 parts ethanol, 10-35 parts water, 55-65 parts water-based polyurethane emulsion, 0.2-0.5 parts dispersant, 0.1-0.5 parts defoamer, 2-4 parts aluminum tripolyphosphate, 7-15 parts pigment, 0.8-1.2 parts ultraviolet absorber, and 2-3 parts antioxidant.

[0041] A second aspect of the present invention provides a method for preparing the water-based printing ink described in the first aspect of the present invention, comprising the following steps:

[0042] (1) Mix 30-50% of the formulation amount of ethanol and water, then add 50-65% of the formulation amount of waterborne polyurethane emulsion and stir at a speed of 300-500 rpm until uniform.

[0043] (2) Next, add dispersant, defoamer, aluminum tripolyphosphate and pigment, adjust the stirring speed to 800-1000 rpm and continue stirring for 30-60 minutes;

[0044] (3) Grind the material obtained in step (2) two to three times with a sand mill at 40 to 45°C until the fineness is ≤15μm;

[0045] (4) Add the remaining ethanol, water, water-based polyurethane emulsion, ultraviolet absorber and antioxidant solution while stirring. Stir at 400-600 rpm for 5-20 minutes to obtain the water-based printing ink.

[0046] A third aspect of the present invention provides an application of the water-based printing ink described in the first aspect of the present invention in the fields of gravure printing or flexographic printing.

[0047] A fourth aspect of the present invention provides a printed article obtained by printing with an aqueous printing ink comprising the water-based printing ink described in the first aspect of the present invention.

[0048] Preferably, the printed article is obtained by printing the water-based printing ink on a substrate.

[0049] Preferably, in the printed article, the substrate is selected from non-absorbent substrates; more preferably, the substrate includes at least one of OPP, PE, PET or paper.

[0050] Preferably, the printed article is selected from outdoor printed articles; more preferably, the printed article includes at least one of outdoor posters, outdoor billboards, vehicle advertisements, packaging boxes, paper bags or plastic bags.

[0051] Printed products made using the water-based printing ink described in the first aspect of this invention can maintain vibrant colors and prevent fading even in outdoor environments, ensuring the quality and durability of the printed products.

[0052] The beneficial effects of this invention are:

[0053] This invention uses waterborne polyurethane emulsion as the main resin, combined with aluminum tripolyphosphate, ultraviolet absorbers and antioxidants, to obtain waterborne printing ink with good weather resistance and adhesion properties. The printed sample does not change color after long-term use and has good durability. The waterborne printing ink provided by this invention has wide applications in gravure printing or flexographic printing.

[0054] Specifically, compared with the prior art, the present invention has the following advantages:

[0055] 1. The aluminum tripolyphosphate of the present invention has excellent rust and corrosion prevention properties, which can protect the ink surface from the erosion of air and moisture, and improve the weather resistance and durability of the ink; it also has good hydrolytic stability, which can effectively improve the water resistance of water-based inks; in addition, it can enhance the interaction force between pigments in the ink, thereby improving the anti-blocking properties of the ink, keeping the ink bright and colorfast, and ensuring the quality and durability of printed products.

[0056] 2. The ultraviolet absorber of this invention has a highly efficient absorption and shielding effect on ultraviolet rays, which can effectively improve the anti-aging ability of the ink layer, enhance weather resistance, and extend the service life of the ink layer; in addition, it can effectively prevent fogging on the ink surface, thus improving the anti-fogging performance of the ink. Furthermore, the use of the ultraviolet absorber in combination with antioxidants can effectively inhibit the oxidation and flocculation of pigments in the ink, thereby improving the storage stability of the ink.

[0057] 3. This invention uses ethanol and water (especially deionized water) as solvents, which produce no harmful gases after use and are environmentally friendly; in addition, the drying speed is fast, printing can be completed in a short time, improving production efficiency, and the printing effect is good, with bright colors and clear patterns, which can meet various printing requirements. Detailed Implementation

[0058] The following specific embodiments further illustrate the content of the present invention in detail. It should also be understood that the following embodiments are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the principles described herein are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make selections within a suitable range based on the description herein, and are not intended to be limited to the specific data in the examples below. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following embodiments and comparative examples can be obtained from conventional commercial sources or by existing known methods.

[0059] It should be noted that, in the embodiments of the present invention,

[0060] The waterborne polyurethane emulsion used was purchased from Guangdong Xinhui Chemical Co., Ltd., model: XH-FW358 waterborne polyurethane emulsion;

[0061] The dispersant model is: BYK-180 aqueous dispersant from Germany;

[0062] The defoamer model is: BYK-019 water-based defoamer from Germany;

[0063] Aluminum tripolyphosphate was purchased from Changzhou Akode New Material Technology Co., Ltd., model number: A-ATW-1;

[0064] The red pigment was purchased from Shandong Xuanyang New Materials Co., Ltd., and the model number is: Permanent Red F2R.

[0065] The ultraviolet absorber was purchased from Shanghai Huzheng Nanotechnology Co., Ltd., model number: ZW-5 water-based ultraviolet absorber;

[0066] The antioxidant was purchased from Tianjin Lianlong New Material Co., Ltd., and its model number is Antioxidant 1010.

[0067] In the embodiments of the present invention, the method for preparing the antioxidant solution is as follows:

[0068] (1) Weigh out the following by weight percentage: 60% ethanol, 20% isopropanol, and 20% antioxidant;

[0069] (2) Mix ethanol and isopropanol evenly, then add antioxidant and stir until completely dissolved to obtain antioxidant solution.

[0070] Example 1 and Comparative Examples 1-7

[0071] Example 1 and Comparative Examples 1-7 each provide a water-based printing ink. The specific raw materials and their formulations are shown in Table 1. The preparation method includes the following steps:

[0072] (1) Add the first amount of ethanol and deionized water to the mixing tank, add the first amount of water-based polyurethane emulsion, and stir at a speed of 300-500 rpm until uniform.

[0073] (2) Under low-speed dispersion conditions, slowly add water-based dispersant, water-based defoamer, aluminum tripolyphosphate (not added in comparative examples 3, 5 to 7), and pigment, adjust the stirring speed to 800 to 1000 rpm, and continue stirring for 40 minutes;

[0074] (3) Grind the material obtained in step (2) two to three times in a sand mill at a constant temperature of 40℃ until the fineness is ≤15μm;

[0075] (4) Add the second amount of ethanol, deionized water, waterborne polyurethane emulsion, waterborne ultraviolet absorber (not added in comparative examples 2, 4, 6, and 7), and antioxidant solution (not added in comparative examples 1, 4, 5, and 7) while stirring. Stir at a speed of 400-600 rpm for 10 minutes to obtain the waterborne printing ink.

[0076] Table 1. Raw materials and their proportions (wt%) for Examples 1 and Comparative Examples 1-7

[0077]

[0078]

[0079] Performance testing

[0080] The performance of the water-based printing inks prepared in Example 1 and Comparative Examples 1-7 was tested. The specific test steps are as follows:

[0081] 1. The water-based printing inks of Examples 1 and 7 were used to make printed products on OPP film substrates using a colorimeter and stored at room temperature for 24 hours to reach a stable state.

[0082] 2. Cut the printed materials in half, keeping one half in a cool, shaded indoor place as a standard sample. Place the other half as a control sample in a xenon lamp test chamber for aging tests. The light intensity of the xenon lamp test chamber is set to 450W / m2, the temperature to 45℃~50℃, and the humidity to 65%~70%. The test durations are 50 hours, 100 hours, 150 hours, 200 hours, and 300 hours.

[0083] 3. Using a Cascima X-rite CI60 colorimeter, the color difference and adhesion of the printed comparison sample and the corresponding printed standard sample were tested for aging test durations of 50 hours, 100 hours, 150 hours, 200 hours, and 300 hours.

[0084] 4. Classify all printed materials according to their lightfastness rating. The specific classification criteria are as follows:

[0085] Level 8: Excellent sun resistance, ΔE ≤ 1 before and after sun exposure;

[0086] Level 7: Excellent sun resistance, ΔE ≤ 2 before and after sun exposure;

[0087] Level 6: Good sun resistance, ΔE ≤ 4 before and after sun exposure;

[0088] Level 4-5: Moderate sun resistance, ΔE ≤ 40 before and after sun exposure;

[0089] Level 2-3: Poor sun resistance, ΔE < 60 before and after sun exposure;

[0090] Grade 1: Poor sun resistance, ΔE > 60 before and after sun exposure.

[0091] The performance test results of Example 1 and Comparative Examples 1 to 7 are shown in Table 2.

[0092] Table 2 Performance test results of Example 1 and Comparative Examples 1-7

[0093]

[0094]

[0095] Analysis of the results in Table 2 shows that:

[0096] Example 1 uses aluminum tripolyphosphate A-ATW-1, water-based ultraviolet absorber ZW-5, and antioxidant solution. After aging test in a xenon lamp test chamber for 300 hours, the color difference value ΔE = 1.6, corresponding to a sun resistance level of 7, indicating good sun resistance performance; the adhesion fastness is 95%, and the overall ink layer fastness is good.

[0097] The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 did not add an antioxidant solution, while all other materials were the same. After 300 hours of aging test in a xenon lamp test chamber, the color difference value ΔE of Comparative Example 1 was 2.6, corresponding to a sun resistance rating of 6, which is lower than the sun resistance rating of 7 of Example 1; the adhesion fastness was 92%, which is lower than the adhesion fastness of 95% of Example 1.

[0098] The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 did not contain the aqueous UV absorber ZW-5, while all other materials were the same. After 300 hours of aging test in a xenon lamp test chamber, the color difference value ΔE of Comparative Example 2 was 2.8, corresponding to a sun resistance rating of 6, which is lower than the sun resistance rating of 7 in Example 1; the adhesion fastness was 91%, which is lower than the adhesion fastness of 95% in Example 1.

[0099] The difference between Comparative Example 3 and Example 1 is that Comparative Example 3 did not contain aluminum tripolyphosphate A-ATW-1, while the other materials were the same. After 300 hours of aging test in a xenon lamp test chamber, the color difference value ΔE of Comparative Example 3 was 2.1, corresponding to a sun resistance rating of 6, which is lower than the sun resistance rating of 7 of Example 1; the adhesion fastness was 82%, which is lower than the adhesion fastness of 95% of Example 1.

[0100] The difference between Comparative Example 4 and Example 1 is that Comparative Example 4 did not contain the aqueous UV absorber ZW-5 and antioxidant solution, while all other materials were the same. After 300 hours of aging test in a xenon lamp test chamber, the color difference value ΔE of Comparative Example 4 was 4.5, corresponding to a sun resistance rating of 4-5, which is lower than the sun resistance rating of 7 in Example 1; its adhesion fastness was 90%, lower than the 95% adhesion fastness of Example 1.

[0101] The difference between Comparative Example 5 and Comparative Example 1 is that Comparative Example 5 did not contain aluminum tripolyphosphate A-ATW-1, while the other materials were the same. After 300 hours of aging test in a xenon lamp test chamber, the color difference value ΔE of Comparative Example 5 was 3.2, corresponding to a lightfastness rating of 6, which is lower than that of Comparative Example 1 (color difference value ΔE = 2.6); its adhesion fastness was 80%, lower than that of Comparative Example 1 (adhesion fastness of 92%).

[0102] The difference between Comparative Example 6 and Comparative Example 2 is that Comparative Example 6 did not contain aluminum tripolyphosphate A-ATW-1, while all other materials were the same. After 300 hours of aging test in a xenon lamp test chamber, Comparative Example 6 had a color difference value ΔE = 3.5, corresponding to a lightfastness rating of 6, which is lower than that of Comparative Example 2 (color difference value ΔE = 2.8); its adhesion fastness was 79%, lower than that of Comparative Example 2 (91%).

[0103] The difference between Comparative Example 7 and Comparative Example 3 is that Comparative Example 7 did not contain the aqueous UV absorber ZW-5 and antioxidant solution; all other materials were the same. After 300 hours of aging testing in a xenon lamp test chamber, Comparative Example 7 had a color difference value ΔE = 4.8, corresponding to a sun resistance rating of 4-5, which is lower than that of Comparative Example 3 (color difference value ΔE = 2.1); its adhesion fastness was 75%, lower than the 82% adhesion fastness of Comparative Example 3.

[0104] As can be seen from Examples 1 and 3, 1 and 5, 2 and 6, 4 and 7, the addition of aluminum tripolyphosphate is beneficial to improving the adhesion of the ink. As can be seen from Comparative Examples 1, 2 and 4, both UV absorbers and antioxidants are beneficial to improving the lightfastness and adhesion of the ink. As can be seen from Examples 1, 1 and 2, the simultaneous use of UV absorbers and antioxidants is even more beneficial to improving the lightfastness of the ink.

[0105] As can be seen from the above analysis, the aluminum tripolyphosphate of the present invention has superior rust and corrosion prevention properties, protecting the ink surface from erosion by air and moisture, and improving the weather resistance and durability of the ink; it also has good hydrolytic stability, which can effectively improve the water resistance of water-based inks; in addition, it can enhance the interaction force between pigments in the ink, thereby improving the ink's anti-blocking properties, keeping the ink bright and colorfast, and ensuring the quality and durability of printed products. The ultraviolet absorber of the present invention has a highly efficient absorption and shielding effect on ultraviolet rays, which can effectively improve the anti-aging ability of the ink layer, enhance weather resistance, and extend the service life of the ink layer; in addition, it can effectively prevent the formation of fog on the ink surface, improving the ink's anti-fogging performance. Furthermore, the use of ultraviolet absorbers in combination with antioxidants can effectively inhibit the oxidation and flocculation of pigments in the ink, thereby improving the storage stability of the ink. Moreover, the present invention uses ethanol and deionized water as solvents, which produce no harmful gases after use and is environmentally friendly; it also dries quickly, allowing printing to be completed in a short time, improving production efficiency, and producing good printing effects with bright colors and clear patterns, meeting various printing requirements.

[0106] In summary, this invention uses waterborne polyurethane emulsion as the main resin, combined with aluminum tripolyphosphate, ultraviolet absorbers, and antioxidants, to obtain a waterborne printing ink with good weather resistance and adhesion properties. Furthermore, the printed sample does not change color after prolonged use, demonstrating excellent durability. The waterborne printing ink provided by this invention has wide applications in gravure printing and flexographic printing.

Claims

1. A water-based printing ink, characterized in that, The preparation materials include the following parts by weight: 5-20 parts ethanol, 10-35 parts water, 50-70 parts waterborne polyurethane emulsion, 0.2-0.5 parts dispersant, 0.1-0.5 parts defoamer, 1-5 parts aluminum tripolyphosphate, 7-15 parts pigment, 0.5-2 parts ultraviolet absorber, and 0.5-5 parts antioxidant; The solid content of the aqueous polyurethane emulsion is 30-40 wt%; the pH value of the aqueous polyurethane emulsion is 6-10; the aqueous polyurethane emulsion is selected from XHFW-358 aqueous polyurethane emulsion. The mass percentage of the residue on a 500-mesh sieve of the aluminum tripolyphosphate is ≤1%; the mass percentage of the volatile matter at 105°C of the aluminum tripolyphosphate is ≤1%; the aluminum tripolyphosphate is selected from A-ATW-1; The ultraviolet absorber is selected from ZW-5 water-based ultraviolet absorber; The antioxidant includes at least one of antioxidant 1010, antioxidant 1076, or antioxidant 264.

2. The water-based printing ink according to claim 1, characterized in that, The pigment includes at least one of yellow, red, blue, black, or green pigments.

3. The method for preparing the water-based printing ink according to any one of claims 1 to 2, characterized in that, Includes the following steps: (1) Mix 30-50% of the formulation amount of ethanol and water, then add 50-65% of the formulation amount of waterborne polyurethane emulsion and stir at a speed of 300-500 rpm until uniform. (2) Next, add dispersant, defoamer, aluminum tripolyphosphate and pigment, adjust the stirring speed to 800~1000 rpm, and continue stirring for 30~60 minutes; (3) Grind the material obtained in step (2) two to three times at 40~45℃ using a sand mill until the fineness is ≤15μm; (4) Add the remaining ethanol, water, water-based polyurethane emulsion, ultraviolet absorber and antioxidant solution while stirring. Stir at 400-600 rpm for 5-20 minutes to obtain the water-based printing ink.

4. The water-based printing ink according to any one of claims 1 to 2 is used in the fields of gravure printing or flexographic printing.

5. A printed article, characterized in that, It is printed using water-based printing inks as described in any one of claims 1 to 2.

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