Printing coating for colored paper and its preparation method

Abstract

This invention relates to the field of coating technology, specifically to a printing coating for colored paper and its preparation method. In the preparation process, this invention incorporates dithiol dihydroxyacetic acid to increase the crosslinking points of the system, and trimethylolpropane tris(2-methyl-1-azacyclopropane propionate) containing an unstable aziridine three-membered ring to improve the degree of crosslinking. It also introduces isoborneol methacrylate to reduce internal stress, effectively balancing the crosslinking density and volume shrinkage of the system, resulting in a coating with excellent adhesion. Furthermore, this invention adds the bifunctional monomer 1,6-hexanediol diacrylate to make the network structure more uniform and provide anti-photooxidation properties, making the system less prone to oxidative discoloration. The addition of tripropylene glycol diacrylate reduces the risk of yellowing caused by small molecule migration. Therefore, the coating obtained in this way has significant anti-yellowing effects, preventing color distortion of colored paper and maintaining the appearance stability of the colored paper.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a printing coating for colored paper and its preparation method. Background Technology

[0002] The core function of coatings for colored paper printing is to treat the surface of paper to improve the basic surface properties of the colored paper substrate and optimize its printing performance. Its main function is not to directly present images and text, but rather to provide an optimized surface for subsequent printing processes, playing a crucial role in ensuring the expressiveness and durability of the final printed product. However, existing colored paper printing coatings, in order to achieve excellent ink absorption and color performance, often focus on building porous structures and using high-concentration pigments. This can sometimes weaken the adhesion between the coating and the paper substrate, leading to easy edge lifting, peeling, and flaking after coating formation. Coating damage is particularly prominent during processing such as die-cutting and folding of colored paper. Furthermore, most coatings have poor anti-yellowing properties, resulting in dull colors and reduced vibrancy, severely lowering the commercial value of the colored paper and failing to meet the market's core demand for high adhesion and high anti-yellowing properties in colored paper.

[0003] Therefore, developing a printing coating with excellent adhesion to colored paper substrates and long-lasting anti-yellowing effect, as well as its preparation method, has become a technical challenge that urgently needs to be overcome in the field of colored paper processing materials. Summary of the Invention

[0004] To address the problems existing in the prior art, the purpose of this invention is to provide a printing coating for colored paper and a method for preparing the same.

[0005] The objective of this invention can be achieved through the following technical solutions: The first aspect of this invention provides a method for preparing printing coatings for colored paper, comprising the following steps: (1) Dissolve the first part of tri-n-butylborane in ethylene glycol butyl ether, heat up to obtain mixture A, mix the resin emulsion, the first part of trimethylolpropane tris(2-methyl-1-azacyclopropane propionate) and the second part of tri-n-butylborane and add them evenly to mixture A. After the addition is complete, control the temperature and keep it warm once. Add dithiol dihydroxyacetic acid and the second part of trimethylolpropane tris(2-methyl-1-azacyclopropane propionate) in sequence, stir, and then add 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, isoborneol methacrylate and azobisisobutyronitrile and mix well. Control the temperature and keep it warm a second time to obtain mixture B. (2) Mix the mixture B, anhydrous ethanol, deionized water, film-forming agent, leveling agent and defoamer, and stir at a controlled speed. Then add nano silica and stir at a controlled speed to remove bubbles, and the finished product of printing coating for colored paper is obtained.

[0006] As a further aspect of the present invention, in step (1), the mass ratio of the first portion of tri-n-butylborane to ethylene glycol butyl ether is 2-2.2:6-12; The mass ratio of the mixture A, resin emulsion, first part trimethylolpropane tris(2-methyl-1-azacyclopropane propionate), second part tri-n-butylborane, dithiol dihydroxyacetic acid, second part trimethylolpropane tris(2-methyl-1-azacyclopropane propionate), 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, isoborneol methacrylate, and azobisisobutyronitrile is 8-10:82-88:2-2.5:2-2.2:5-6:2-2.5:16-21:8-10:3.5-5:3-4.

[0007] As a further embodiment of the present invention, the heating in step (1) is to raise the temperature to 60-70℃; the time for uniformly adding the mixture A is within 2-3 hours; the temperature for the first temperature control and heat preservation is 70-80℃ and the time is 1-1.5 hours; the stirring time is 2-3 hours; the temperature for the second temperature control and heat preservation is 70-75℃ and the time is 0.5-1 hours.

[0008] As a further aspect of the present invention, the method for preparing the resin emulsion in step (1) includes the following steps: S1, mix methyl methacrylate, butyl acrylate, acrylic acid and hydroxyethyl acrylate to obtain preemulsion A; Methyl methacrylate, butyl acrylate, and N-hydroxymethylacrylamide are mixed to obtain preemulsion B; S2, add the active emulsifier to deionized water and stir to dissolve, then add the first part of pre-emulsion A and stir to mix well. Heat up, add initiator I, heat up and keep warm for 1, then add the second part of pre-emulsion A, pre-emulsion B and initiator II in sequence and evenly, then add initiator III, heat up and keep warm for 2, cool, filter, and the resin emulsion is obtained.

[0009] Further, the mass ratio of methyl methacrylate, butyl acrylate, acrylic acid and hydroxyethyl acrylate in step S1 is 35-50:8-12:1-4:1-4; The mass ratio of methyl methacrylate, butyl acrylate and N-hydroxymethylacrylamide is 33-45:16-24:2-5.

[0010] Further, the mass ratio of the active emulsifier, deionized water, first pre-emulsion A, initiator I, second pre-emulsion A, pre-emulsion B, initiator II, and initiator III in step S2 is 2.5-5:150-280:23-35:2.5-4:23-35:51-74:5-8:2.5-4.

[0011] Furthermore, the active emulsifier comprises isotridecyl alcohol polyoxyethylene ether and polyoxyethylene alkyl ether in a mass ratio of 2-2.2:1.

[0012] Furthermore, initiator I, initiator II, and initiator III are all 2.5-5 wt% potassium persulfate aqueous solutions.

[0013] Further, in step S2, the heating is raised to 70-75℃; the reheating and holding step I is raised to 80-82℃ and held for 30-35 minutes; the time for adding the second part of preemulsion A, preemulsion B and initiator II in sequence and evenly is controlled at 4.5-5 hours; the heating and holding step II is raised to 85-90℃ and held for 30-35 minutes; the cooling is cooled to room temperature; and the filtration is filtered with 200-mesh gauze.

[0014] As a preferred technical solution of the present invention, the mass ratio of the mixture B, anhydrous ethanol, deionized water, film-forming aid, leveling agent, defoamer and nano silica in step (2) is 90-100:20-25:30-35:0.5-1.5:0.5-1:0.6-1:6-7.5.

[0015] Further, the film-forming aid includes ethylene glycol ethyl ether or ethylene glycol butyl ether; the leveling agent includes any one of leveling agent BYK-307, leveling agent BYK333, and leveling agent BYK-331; the defoamer includes any one of defoamer BYK-016, defoamer BYK-012, defoamer BYK-028, and defoamer BYK-011.

[0016] As a preferred technical solution of the present invention, the speed of the post-speed controlled stirring in step (2) is 300-400 r / min and the time is 5-10 min; the speed of the subsequent addition of nano-silica stirring is 600-650 r / min and the time is 10-15 min; the time for degassing is 10-12 min.

[0017] A second aspect of the present invention provides a printing coating for colored paper prepared by the above-described preparation method.

[0018] The beneficial effects of this invention are: (1) The present invention increases the crosslinking points of the system by using carboxyl-containing dithiol dihydroxyacetic acid, and increases the crosslinking degree of the system by using trimethylolpropane tris(2-methyl-1-azacyclopropane propionate) containing an unstable aziridine three-membered ring, thereby enhancing the cohesive force of the system. In addition, isobornyl methacrylate is introduced, which has small volume shrinkage when participating in curing, which helps to reduce the internal stress of the system, improve the adhesion between the coating and the substrate, and reduce the risk of coating cracking after curing. Therefore, the three components added in the present invention can take into account both crosslinking density and volume shrinkage, so that the coating has excellent adhesion.

[0019] (2) 1,6-Hexanediol diacrylate is a bifunctional monomer. Its long chain structure increases the spacing between crosslinking points and makes the network structure more uniform. During the curing process, it can form a network structure with the main chain of the system to play an anti-photooxidation role, making the system less prone to oxidation and discoloration. Moreover, it has high activity and high conversion rate in participating in the polymerization of the system, which can greatly reduce the probability of yellowing of the system. The molecular chain of dipropylene glycol diacrylate is mainly composed of saturated aliphatic carbon chains. After curing, the system has good density, which reduces the risk of yellowing caused by the migration of small molecules. Therefore, the coating prepared by this method has significant anti-yellowing effect, making the color of colored paper less likely to be distorted and maintaining the appearance stability of colored paper. Detailed Implementation

[0020] The technical solution of the present invention is illustrated below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or defining the scope of the present invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the present invention.

[0021] To better understand the above technical solutions, exemplary embodiments of the present invention are described in more detail below. While exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art.

[0022] The isomeric tridecyl alcohol polyoxyethylene ether used in this invention, model: E-1308, was purchased from Linyi Guoli Chemical Co., Ltd. The polyoxyethylene alkyl ether used, model: 1135S-70, was purchased from: Xingtianwai Chemical (Shanghai) Co., Ltd. The nano-silica used, model: HN-SP30T, was purchased from Hangzhou Hengna New Materials Co., Ltd. The above will not be repeated hereafter; The present invention will be further described below with reference to the following embodiments.

[0023] Example 1 The method for preparing a resin emulsion includes the following steps: S1, mix methyl methacrylate, butyl acrylate, acrylic acid and hydroxyethyl acrylate in a mass ratio of 35:10:4:2.5 to obtain preemulsion A; Methyl methacrylate, butyl acrylate and N-hydroxymethylacrylamide are mixed in a mass ratio of 45:20:5 to obtain preemulsion B; S2, add the active emulsifier to deionized water and stir to dissolve, then add the first part of pre-emulsion A and stir to mix well. Heat to 73°C, add initiator I, then heat to 82°C and keep warm for 30 minutes. Within 5 hours, add the second part of pre-emulsion A, pre-emulsion B and initiator II in sequence and evenly, then add initiator III, heat to 90°C and keep warm for 30 minutes, cool to room temperature, and filter with 200-mesh gauze to obtain the resin emulsion. The mass ratio of the active emulsifier, deionized water, first preemulsion A, initiator I, second preemulsion A, preemulsion B, initiator II, and initiator III is 2.5:215:35:2.5:23:63:5:4. The active emulsifier comprises isotridecyl alcohol polyoxyethylene ether and polyoxyethylene alkyl ether in a mass ratio of 2:1; Initiator I, Initiator II, and Initiator III are all 5 wt% potassium persulfate aqueous solutions.

[0024] Example 2 The method for preparing a resin emulsion includes the following steps: S1, mix methyl methacrylate, butyl acrylate, acrylic acid and hydroxyethyl acrylate in a mass ratio of 42.5:8:1:4 to obtain preemulsion A; Methyl methacrylate, butyl acrylate and N-hydroxymethylacrylamide are mixed in a mass ratio of 39:16:2 to obtain preemulsion B; S2, add the active emulsifier to deionized water and stir to dissolve, then add the first part of pre-emulsion A and stir to mix well. Heat to 70°C, add initiator I, then heat to 80°C and keep warm for 35 min. Over 4.5 h, add the second part of pre-emulsion A, pre-emulsion B and initiator II in sequence and evenly, then add initiator III. Heat to 85°C and keep warm for 33 min. Cool to room temperature and filter with 200 mesh gauze to obtain the resin emulsion. The mass ratio of the active emulsifier, deionized water, first preemulsion A, initiator I, second preemulsion A, preemulsion B, initiator II, and initiator III is 3.7:150:23:4:29:74:8:2.5. The active emulsifier comprises isotridecyl alcohol polyoxyethylene ether and polyoxyethylene alkyl ether in a mass ratio of 2.1:1; Initiator I, Initiator II, and Initiator III are all 2.5 wt% potassium persulfate aqueous solutions.

[0025] Example 3 The method for preparing a resin emulsion includes the following steps: S1, mix methyl methacrylate, butyl acrylate, acrylic acid and hydroxyethyl acrylate in a mass ratio of 50:12:2.5:1 to obtain preemulsion A; Methyl methacrylate, butyl acrylate and N-hydroxymethylacrylamide are mixed in a mass ratio of 33:24:3.5 to obtain preemulsion B; S2, add the active emulsifier to deionized water and stir to dissolve, then add the first part of pre-emulsion A and stir to mix well. Heat to 75°C, add initiator I, then heat to 81°C and keep warm for 33 min. Over 4.6 h, add the second part of pre-emulsion A, pre-emulsion B and initiator II in sequence and evenly, then add initiator III. Heat to 88°C and keep warm for 35 min. Cool to room temperature and filter with 200 mesh gauze to obtain the resin emulsion. The mass ratio of the active emulsifier, deionized water, first preemulsion A, initiator I, second preemulsion A, preemulsion B, initiator II, and initiator III is 5:280:29:3.3:35:51:6.5:3.3; The active emulsifier comprises isotridecyl alcohol polyoxyethylene ether and polyoxyethylene alkyl ether in a mass ratio of 2.2:1; Initiator I, Initiator II, and Initiator III are all 5 wt% potassium persulfate aqueous solutions.

[0026] Example 4 A method for preparing a printing coating for colored paper includes the following steps: (1) Dissolve the first part of tri-n-butylborane in ethylene glycol butyl ether and heat to 60°C to obtain mixture A. Mix the resin emulsion, the first part of trimethylolpropane tris(2-methyl-1-azacyclopropane propionate) and the second part of tri-n-butylborane and add them evenly to mixture A within 2.5h. After the addition is complete, keep the temperature at 80°C for 1h. Add dithiol dihydroxyacetic acid and the second part of trimethylolpropane tris(2-methyl-1-azacyclopropane propionate) in sequence and stir for 2.5h. Then add 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, isoborneol methacrylate and azobisisobutyronitrile and mix well. Keep the temperature at 70°C for 0.5h to obtain mixture B. The mass ratio of the first portion of tri-n-butylborane to ethylene glycol butyl ether is 2.2:9; The mass ratio of the mixture A, the resin emulsion prepared in Example 2, the first part of trimethylolpropane tris(2-methyl-1-azacyclopropane propionate), the second part of tri-n-butylborane, dithiol dihydroxyacetic acid, the second part of trimethylolpropane tris(2-methyl-1-azacyclopropane propionate), 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, isoborneol methacrylate, and azobisisobutyronitrile is 9:82:2.5:2.1:5:2.5:18.5:8:5:3. (2) Mix the mixture B, anhydrous ethanol, deionized water, film-forming aid, leveling agent and defoamer, and stir at 300 r / min for 5 min. Then add nano silica and stir at 650 r / min for 13 min. Remove the bubbles for 11 min to obtain the finished product of the printing coating for colored paper. The mass ratio of the mixture B, anhydrous ethanol, deionized water, film-forming aid, leveling agent, defoamer, and nano silica is 100:20:35:0.5:0.5:0.8:6. The film-forming aid includes ethylene glycol ethyl ether; the leveling agent includes leveling agent BYK-307; and the defoamer includes defoamer BYK-028.

[0027] Example 5 A method for preparing a printing coating for colored paper includes the following steps: (1) Dissolve the first part of tri-n-butylborane in ethylene glycol butyl ether and heat to 70°C to obtain mixture A. Mix the resin emulsion, the first part of trimethylolpropane tris(2-methyl-1-azacyclopropane propionate) and the second part of tri-n-butylborane and add them evenly to mixture A within 2 hours. After the addition is complete, keep the temperature at 70°C for 1 hour. Add dithiol dihydroxyacetic acid and the second part of trimethylolpropane tris(2-methyl-1-azacyclopropane propionate) in sequence and stir for 2 hours. Then add 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, isoborneol methacrylate and azobisisobutyronitrile and mix well. Keep the temperature at 73°C for 1 hour to obtain mixture B. The mass ratio of the first portion of tri-n-butylborane to ethylene glycol butyl ether is 2:6; The mass ratio of the mixture A, the resin emulsion prepared in Example 3, the first part of trimethylolpropane tris(2-methyl-1-azacyclopropane propionate), the second part of tri-n-butylborane, dithiol dihydroxyacetic acid, the second part of trimethylolpropane tris(2-methyl-1-azacyclopropane propionate), 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, isoborneol methacrylate, and azobisisobutyronitrile is 8:85:2:2:5.5:2:16:9:3.5:4. (2) Mix the mixture B, anhydrous ethanol, deionized water, film-forming aid, leveling agent and defoamer, and stir at 400 r / min for 7.5 min. Then add nano silica and stir at 600 r / min for 10 min. Remove the bubbles for 10 min to obtain the finished product of the printing coating for colored paper. The mass ratio of the mixture B, anhydrous ethanol, deionized water, film-forming aid, leveling agent, defoamer, and nano silica is 90:23:32:1:0.8:0.6:6.8. The film-forming aid includes ethylene glycol butyl ether; the leveling agent includes leveling agent BYK333; and the defoamer includes defoamer BYK-012.

[0028] Example 6 A method for preparing a printing coating for colored paper includes the following steps: (1) Dissolve the first part of tri-n-butylborane in ethylene glycol butyl ether and heat to 65°C to obtain mixture A. Mix the resin emulsion, the first part of trimethylolpropane tris(2-methyl-1-azacyclopropane propionate) and the second part of tri-n-butylborane and add them evenly to mixture A within 3 hours. After the addition is complete, keep the temperature at 75°C for 1.5 hours. Add dithiol dihydroxyacetic acid and the second part of trimethylolpropane tris(2-methyl-1-azacyclopropane propionate) in sequence and stir for 3 hours. Then add 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, isoborneol methacrylate and azobisisobutyronitrile and mix well. Keep the temperature at 75°C for 1 hour to obtain mixture B. The mass ratio of the first portion of tri-n-butylborane to ethylene glycol butyl ether is 2.1:12; The mass ratio of the mixture A, the resin emulsion prepared in Example 1, the first part of trimethylolpropane tris(2-methyl-1-azacyclopropane propionate), the second part of tri-n-butylborane, dithiol dihydroxyacetic acid, the second part of trimethylolpropane tris(2-methyl-1-azacyclopropane propionate), 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, isoborneol methacrylate, and azobisisobutyronitrile is 10:88:2.3:2.2:6:2.3:21:10:4.2:3.5; (2) Mix the mixture B, anhydrous ethanol, deionized water, film-forming aid, leveling agent and defoamer, and stir at 350 r / min for 10 min. Then add nano silica and stir at 625 r / min for 15 min. Remove the bubbles for 12 min to obtain the finished product of the printing coating for colored paper. The mass ratio of the mixture B, anhydrous ethanol, deionized water, film-forming aid, leveling agent, defoamer, and nano silica is 95:25:30:1.5:1:1:7.5. The film-forming aid includes ethylene glycol ethyl ether; the leveling agent includes leveling agent BYK-331; and the defoamer includes defoamer BYK-016.

[0029] Comparative Example 1 Compared with Example 6, the difference is that dithiol dihydroxyacetic acid is not added in step (1), while the rest remain unchanged.

[0030] Comparative Example 2 Compared with Example 6, the difference is that the first and second portions of trimethylolpropane tris(2-methyl-1-azacyclopropane propionate) are not added in step (1), while the rest remain unchanged.

[0031] Comparative Example 3 Compared with Example 6, the difference is that isoborneol methacrylate is not added in step (1), while the rest remain unchanged.

[0032] Comparative Example 4 Compared with Example 6, the difference is that 1,6-hexanediol diacrylate is not added in step (1), while the rest remain unchanged.

[0033] Comparative Example 5 Compared with Example 6, the difference is that tripropylene glycol diacrylate is not added in step (1), while the rest remain unchanged.

[0034] Test case (1) Adhesion test: The adhesion of the printing coatings for colored paper prepared in Examples 4-6 and Comparative Examples 1-3 was tested according to the national standard GB / T 1720-1979 "Determination of Adhesion of Paint Film". The rating method was: Grade 1 adhesion was the best and Grade 7 adhesion was the worst. The results are shown in Table 1.

[0035] (2) Yellowing resistance test: Referring to the national standard GB / T 9761-2008 "Visual color comparison of paints and varnishes", the paint samples prepared in Examples 4-6 and Comparative Examples 4-5 were compared with the samples that had not undergone the cold and heat alternation test under natural environment by the same observer; the results are shown in Table 1.

[0036] Table 1 As can be seen from the adhesion test results of Examples 4-6 in Table 1, the printing coating for colored paper prepared by the present invention has excellent adhesion. However, as can be seen from the adhesion test results of Comparative Examples 1-3, the adhesion is poor regardless of the addition of any one of dithiol dihydroxyacetic acid, trimethylolpropane tris(2-methyl-1-azacyclopropane propionate) and isoborneol methacrylate. As can be seen from the yellowness test results of Examples 4-6 in Table 1, the printing coating for colored paper prepared by the present invention has significant anti-yellowing effect. From the yellowness test results of Comparative Examples 4-5, it can be concluded that 1,6-hexanediol diacrylate and tripropylene glycol diacrylate both contribute to the anti-yellowing effect of the system.

[0037] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. The illustrative expressions of the above terms in this specification should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0038] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a printing coating for colored paper, characterized in that, Includes the following steps: (1) Dissolve the first part of tri-n-butylborane in ethylene glycol butyl ether, heat up to obtain mixture A, mix the resin emulsion, the first part of trimethylolpropane tris(2-methyl-1-azacyclopropane propionate) and the second part of tri-n-butylborane and add them evenly to mixture A. After the addition is complete, control the temperature and keep it warm once. Add dithiol dihydroxyacetic acid and the second part of trimethylolpropane tris(2-methyl-1-azacyclopropane propionate) in sequence, stir, and then add 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, isoborneol methacrylate and azobisisobutyronitrile and mix well. Control the temperature and keep it warm a second time to obtain mixture B. (2) Mix the mixture B, anhydrous ethanol, deionized water, film-forming agent, leveling agent and defoamer, and stir at a controlled speed. Then add nano silica and stir at a controlled speed to remove bubbles, and the finished product of printing coating for colored paper is obtained.

2. The method for preparing printing coating for colored paper according to claim 1, characterized in that, Step (1) The mass ratio of the first portion of tri-n-butylborane to ethylene glycol butyl ether is 2-2.2:6-12; The mass ratio of the mixture A, resin emulsion, first part trimethylolpropane tris(2-methyl-1-azacyclopropane propionate), second part tri-n-butylborane, dithiol dihydroxyacetic acid, second part trimethylolpropane tris(2-methyl-1-azacyclopropane propionate), 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, isoborneol methacrylate, and azobisisobutyronitrile is 8-10:82-88:2-2.5:2-2.2:5-6:2-2.5:16-21:8-10:3.5-5:3-4.

3. The method for preparing printing coating for colored paper according to claim 1, characterized in that, The preparation method of the resin emulsion in step (1) includes the following steps: S1, mix methyl methacrylate, butyl acrylate, acrylic acid and hydroxyethyl acrylate to obtain preemulsion A; Methyl methacrylate, butyl acrylate, and N-hydroxymethylacrylamide are mixed to obtain preemulsion B; S2, add the active emulsifier to deionized water and stir to dissolve, then add the first part of pre-emulsion A and stir to mix well. Heat up, add initiator I, heat up and keep warm for 1, then add the second part of pre-emulsion A, pre-emulsion B and initiator II in sequence and evenly, then add initiator III, heat up and keep warm for 2, cool, filter, and the resin emulsion is obtained.

4. The method for preparing printing coating for colored paper according to claim 3, characterized in that, The mass ratio of methyl methacrylate, butyl acrylate, acrylic acid, and hydroxyethyl acrylate in step S1 is 35-50:8-12:1-4:1-4; The mass ratio of methyl methacrylate, butyl acrylate and N-hydroxymethylacrylamide is 33-45:16-24:2-5.

5. The method for preparing printing coating for colored paper according to claim 3, characterized in that, The mass ratio of the active emulsifier, deionized water, first pre-emulsion A, initiator I, second pre-emulsion A, pre-emulsion B, initiator II, and initiator III in step S2 is 2.5-5:150-280:23-35:2.5-4:23-35:51-74:5-8:2.5-4.

6. The method for preparing printing coating for colored paper according to claim 5, characterized in that, The active emulsifier comprises isotridecyl alcohol polyoxyethylene ether and polyoxyethylene alkyl ether in a mass ratio of 2-2.2:1; Initiator I, Initiator II, and Initiator III are all 2.5-5 wt% potassium persulfate aqueous solutions.

7. The method for preparing printing coating for colored paper according to claim 1, characterized in that, The mass ratio of the mixture B, anhydrous ethanol, deionized water, film-forming aid, leveling agent, defoamer and nano silica in step (2) is 90-100:20-25:30-35:0.5-1.5:0.5-1:0.6-1:6-7.

5.

8. The method for preparing printing coating for colored paper according to claim 1, characterized in that, The film-forming aid includes ethylene glycol ethyl ether or ethylene glycol butyl ether; The leveling agent includes any one of leveling agent BYK-307, leveling agent BYK333 and leveling agent BYK-331; The defoamer includes any one of defoamer BYK-016, defoamer BYK-012, defoamer BYK-028, and defoamer BYK-011.

9. The method for preparing printing coating for colored paper according to claim 1, characterized in that, The speed of the post-stirring in step (2) is 300-400 r / min and the time is 5-10 min; the speed of the subsequent addition of nano-silica and stirring is 600-650 r / min and the time is 10-15 min; the time for degassing is 10-12 min.

10. A printing coating for colored paper prepared by the preparation method according to any one of claims 1-9.

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