Environment-friendly water-based glazing paint for printing and preparation method thereof

Abstract

The present application provides an environment-friendly water-based glazing oil coating for printing and a preparation method thereof, the environment-friendly water-based glazing oil coating for printing comprises the following raw materials in parts by weight: water-based polyester resin 45-55 parts, water-based acrylic emulsion 30-40 parts, water-based epoxy modified acrylic resin 22-32 parts, filler 5-15 parts, silane coupling agent 3-8 parts, polyvinyl alcohol 2-6 parts, film-forming aid 2-8 parts, thickening agent 2-8 parts, and defoaming agent 0.5-3 parts. The environment-friendly water-based glazing oil coating for printing prepared by the present application has good wear resistance, solvent resistance, adhesion and flexibility, is friendly to the environment, can effectively protect the printed matter when used, and improves the durability and appearance of the printed matter. The present application also provides a preparation method of the water-based glazing oil, which is simple in process, easy to automatically control, high in production efficiency, and conducive to large-scale production.

Description

Technical Field

[0001] This invention relates to the field of varnish technology, specifically to an environmentally friendly water-based varnish coating for printing and its preparation method. Background Technology

[0002] Printing varnishes are coatings used after printing to treat the surface of the ink layer, providing surface protection, enhancing abrasion resistance, and improving the brightness of printed materials. With social development, technological progress, and increasingly stringent environmental requirements, environmentally friendly varnishes are increasingly widely used in the printing industry. Environmentally friendly varnishes generally refer to those with low VOC content, including UV varnishes and water-based varnishes. Their use not only increases the surface smoothness and decorative appeal of printed materials but also effectively protects them, improving durability and ease of use. With the rapid development of the industry, high-end printed materials place higher demands on the overall performance of existing water-based varnishes. However, traditional water-based varnishes, due to limitations in their resin systems and unreasonable ingredient combinations, often result in poor hydrophobicity after film formation. Furthermore, some traditional water-based varnish coatings still lag behind solvent-based varnishes in abrasion resistance, and exhibit poor solvent resistance and adhesion to printed substrates or inks. Further improvements are urgently needed to meet market demands. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of the prior art by providing an environmentally friendly water-based varnish coating for printing. This environmentally friendly water-based varnish coating for printing provides excellent abrasion resistance, solvent resistance, adhesion, and flexibility. It is environmentally friendly and effectively protects printed materials, improving their durability and aesthetic appearance. This invention also provides a method for preparing the water-based varnish. This method has a simple production process, is easy to automate, has high production efficiency, and is conducive to large-scale production.

[0004] The objective of this invention is achieved through the following technical solution: an environmentally friendly water-based varnish coating for printing, comprising the following raw materials in parts by weight: 45-55 parts of water-based polyester resin, 30-40 parts of water-based acrylic emulsion, 22-32 parts of water-based epoxy-modified acrylic resin, 5-15 parts of filler, 3-8 parts of silane coupling agent, 2-6 parts of polyvinyl alcohol, 2-8 parts of film-forming aid, 2-8 parts of thickener, and 0.5-3 parts of defoamer.

[0005] Furthermore, the preparation method of the waterborne epoxy-modified acrylic resin includes the following steps:

[0006] (A1) Take 100 parts of deionized water and 1-4 parts of emulsifier and mix them evenly; then add 20-30 parts of styrene, 15-25 parts of hydroxyethyl acrylate, 5-15 parts of glycidyl methacrylate, 4-8 parts of dodecafluoroheptyl methacrylate and 2-5 parts of γ-methacryloyloxypropyltrimethoxysilane and stir to obtain material A.

[0007] (A2) Take 15 parts of deionized water and 0.5-1.5 parts of initiator and mix them evenly to prepare an initiator solution; take part of material A and part of the initiator solution and add them to the reaction vessel, and react under nitrogen protection; then add the remaining material A and the remaining initiator solution dropwise; after the dropwise addition is complete, raise the temperature to 90-95℃, and then add 0.1-0.4 parts of tert-butyl hydrogen peroxide, keep warm, and obtain material B;

[0008] (A3) Cool down material B, add 5-10 parts of γ-glycidoxypropyltrimethoxysilane and stir to mix, then adjust the pH to 7.0-8.0 with a pH adjuster, perform vacuum degassing, filtration and discharge to obtain waterborne epoxy modified acrylic resin.

[0009] This invention prepares waterborne epoxy-modified acrylic acid using the above-mentioned raw materials and emulsion polymerization method. By adding materials and initiators in stages, the stability of the polymerization reaction and the performance of the product are improved. By adding dodecafluoroheptyl methacrylate and γ-glycidoxypropyltrimethoxysilane in the later stage of the preparation process to carry out crosslinking reaction, the varnish coating can be endowed with good solvent resistance and low surface energy, and the crosslinking density and performance of the varnish coating can be improved.

[0010] Furthermore, in step (A1), the emulsifier is at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, fatty alcohol polyoxyethylene ether, and allyloxynonylphenol polyoxyethylene ether ammonium sulfate.

[0011] Furthermore, in step (A2), the initiator is at least one of ammonium persulfate, potassium persulfate, and sodium bisulfite.

[0012] Furthermore, in step (A3), the pH adjuster is at least one of 2-amino-2-methyl-1-propanol and ammonia.

[0013] Furthermore, the filler is at least one selected from nano-silica, nano-calcium carbonate, nano-talc, and nano-barium sulfate. The particle size of the filler is 20-50 nm.

[0014] Furthermore, the silane coupling agent is at least one of γ-methacryloxypropyltrimethoxysilane and γ-glycidoxypropyltrimethoxysilane.

[0015] Furthermore, the film-forming aid is at least one of dipropylene glycol butyl ether, propylene glycol phenyl ether, and dipropylene glycol methyl ether acetate.

[0016] Furthermore, the thickener is at least one selected from hydroxyethyl cellulose, hydroxypropyl methylcellulose, and methylcellulose.

[0017] The present invention also provides a method for preparing the above-mentioned environmentally friendly water-based varnish coating for printing, comprising the following steps:

[0018] (1) Add silane coupling agent and filler in proportion, stir and mix evenly to obtain filler pretreated with silane coupling agent;

[0019] (2) Add waterborne polyester resin, waterborne acrylic emulsion, waterborne epoxy modified acrylic resin and polyvinyl alcohol in proportion, and stir to mix evenly; then add filler, film-forming aid, thickener and defoamer pretreated with silane coupling agent, stir to mix evenly to obtain finished coating.

[0020] Furthermore, in step (1), silane coupling agent and filler are added in proportion, and then acetic acid is added dropwise to adjust the pH to 4.0-5.0, the temperature is raised to 50-55℃, and the mixture is stirred for 20-60 minutes at a speed of 1000-1500 rpm to obtain filler pretreated with silane coupling agent.

[0021] Furthermore, in step (2), waterborne polyester resin, waterborne acrylic emulsion, waterborne epoxy-modified acrylic resin and polyvinyl alcohol are added in proportion and stirred at a speed of 500-1000 rpm for 20-60 min. Then, filler, film-forming aid, thickener and defoamer pretreated with silane coupling agent are added and stirred at a speed of 800-1200 rpm for 20-60 min to obtain waterborne varnish coating.

[0022] The beneficial effects of this invention are as follows: The environmentally friendly water-based varnish coating for printing of this invention uses a combination of water-based polyester resin, water-based acrylic emulsion, and water-based epoxy-modified acrylic resin as the resin matrix, and is compounded with fillers and silane coupling agents, combined with film-forming aids, defoamers, and other additives. This improves the gloss and smoothness of the coating, endowing the water-based varnish coating with good abrasion resistance, solvent resistance, adhesion, hydrophobicity, and flexibility, and is environmentally friendly. During use, it effectively protects printed materials such as paper printed materials, improving their durability and aesthetic appearance. The preparation method of the water-based varnish provided by this invention is simple, easy to automate, and has high production efficiency, which is conducive to large-scale production. Detailed Implementation

[0023] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments. The content mentioned in the embodiments is not intended to limit the present invention.

[0024] In some embodiments of the present invention, an environmentally friendly water-based varnish coating for printing comprises the following raw materials in parts by weight: 45-55 parts of water-based polyester resin, 30-40 parts of water-based acrylic emulsion, 22-32 parts of water-based epoxy-modified acrylic resin, 5-15 parts of filler, 3-8 parts of silane coupling agent, 2-6 parts of polyvinyl alcohol, 2-8 parts of film-forming aid, 2-8 parts of thickener, and 0.5-3 parts of defoamer.

[0025] In some embodiments of the present invention, the preparation method of the waterborne epoxy-modified acrylic resin includes the following steps:

[0026] (A1) Take 100 parts of deionized water and 1-4 parts of emulsifier and mix them evenly; then add 20-30 parts of styrene, 15-25 parts of hydroxyethyl acrylate, 5-15 parts of glycidyl methacrylate, 4-8 parts of dodecafluoroheptyl methacrylate and 2-5 parts of γ-methacryloyloxypropyltrimethoxysilane and stir. The stirring speed is 800-1400 rpm and the stirring time is 30-60 min to obtain material A;

[0027] (A2) Take 15 parts of deionized water and 0.5-1.5 parts of initiator and mix them evenly to prepare an initiator solution; take 30-50% of material A and 30-50% of the initiator solution and add them to the reactor, heat to 70-75℃ under nitrogen protection, and react for 30-60 minutes; then add the remaining material A and the remaining initiator solution dropwise over 3-4 hours; after the dropwise addition is complete, heat to 90-95℃, then add 0.1-0.4 parts of tert-butyl hydroperoxide, and keep warm for 30-90 minutes to obtain material B;

[0028] (A3) Cool material B to 40-50℃, add 5-10 parts of γ-glycidyl etheroxypropyltrimethoxysilane and stir for 30-60 minutes. Then adjust the pH to 7.0-8.0 with a pH adjuster, perform vacuum degassing, filtration and discharge to obtain waterborne epoxy modified acrylic resin.

[0029] In some embodiments of the present invention, in step (A1), the emulsifier is at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, fatty alcohol polyoxyethylene ether, and allyloxynonylphenol polyoxyethylene ether ammonium sulfate.

[0030] In some embodiments of the present invention, in step (A1), the emulsifier is composed of sodium dodecyl sulfate, fatty alcohol polyoxyethylene ether, and allyloxynonylphenol polyoxyethylene ether ammonium sulfate in a weight ratio of 3-5:2-4:1.

[0031] In some embodiments of the present invention, in step (A2), the initiator is at least one of ammonium persulfate, potassium persulfate, and sodium bisulfite.

[0032] In some embodiments of the present invention, in step (A3), the pH adjuster is at least one of 2-amino-2-methyl-1-propanol and ammonia.

[0033] In some embodiments of the present invention, the filler is at least one selected from nano-silica, nano-calcium carbonate, nano-talc, and nano-barium sulfate. The particle size of the filler is 20-50 nm.

[0034] In some embodiments of the present invention, the silane coupling agent is at least one of γ-methacryloyloxypropyltrimethoxysilane and γ-glycidoxypropyltrimethoxysilane.

[0035] In some embodiments of the present invention, the film-forming aid is at least one of dipropylene glycol butyl ether, propylene glycol phenyl ether, and dipropylene glycol methyl ether acetate.

[0036] In some embodiments of the present invention, the film-forming aid is composed of propylene glycol phenyl ether and dipropylene glycol butyl ether in a weight ratio of 1-2:1.

[0037] In some embodiments of the present invention, the thickener is at least one of hydroxyethyl cellulose (HEC), hydroxypropyl methylcellulose (HPMC), and methylcellulose (MC).

[0038] In some embodiments of the present invention, the defoamer is at least one of silicone defoamers, mineral oil defoamers, and polyether defoamers.

[0039] In some embodiments of the present invention, a method for preparing an environmentally friendly water-based varnish coating for printing includes the following steps:

[0040] (1) Add silane coupling agent and filler in proportion, stir and mix evenly to obtain filler pretreated with silane coupling agent;

[0041] (2) Add waterborne polyester resin, waterborne acrylic emulsion, waterborne epoxy modified acrylic resin and polyvinyl alcohol in proportion, and stir to mix evenly; then add filler, film-forming aid, thickener and defoamer pretreated with silane coupling agent, stir to mix evenly to obtain finished coating.

[0042] In some embodiments of the present invention, in step (1), silane coupling agent and filler are added in proportion, and then acetic acid is added dropwise to adjust the pH to 4.0-5.0, the temperature is raised to 50-55℃, and the mixture is stirred for 20-60 minutes at a speed of 1000-1500 rpm to obtain filler pretreated with silane coupling agent.

[0043] In some embodiments of the present invention, in step (2), waterborne polyester resin, waterborne acrylic emulsion, waterborne epoxy-modified acrylic resin and polyvinyl alcohol are added in proportion and stirred at a speed of 500-1000 rpm for 20-60 min. Then, filler, film-forming aid, thickener and defoamer pretreated with silane coupling agent are added and stirred at a speed of 800-1200 rpm for 20-60 min to obtain waterborne varnish coating.

[0044] Example 1

[0045] An environmentally friendly water-based varnish coating for printing comprises the following raw materials in parts by weight: 50 parts water-based polyester resin, 35 parts water-based acrylic emulsion, 25 parts water-based epoxy-modified acrylic resin, 12 parts filler, 5 parts silane coupling agent, 3 parts polyvinyl alcohol, 4 parts film-forming aid, 4 parts thickener, and 1.5 parts defoamer. The water-based polyester resin is BASF polyester resin. PE 55WN. The aqueous acrylic emulsion is DSM Neocryl XK-85 aqueous acrylic emulsion. The polyvinyl alcohol is Wanwei PVA2488. The defoamer is a defoamer. Foamex 8420.

[0046] The preparation method of waterborne epoxy-modified acrylic resin includes the following steps:

[0047] (A1) Take 100 parts of deionized water and 2 parts of emulsifier and mix them evenly; then add 25 parts of styrene, 20 parts of hydroxyethyl acrylate, 11 parts of glycidyl methacrylate, 7 parts of dodecafluoroheptyl methacrylate and 3 parts of γ-methacryloyloxypropyltrimethoxysilane and stir at 1000 rpm for 60 min to obtain material A.

[0048] (A2) Take 15 parts of deionized water and 1 part of initiator and mix them evenly to prepare an initiator solution; take 40% of material A and 40% of the initiator solution and add them to the reactor, heat to 72°C under nitrogen protection and react for 40 min; then add the remaining material A and the remaining initiator solution dropwise over 4 h; after the dropwise addition is complete, heat to 92°C and then add 0.3 parts of tert-butyl hydrogen peroxide, keep warm for 60 min to obtain material B;

[0049] (A3) Cool material B to 45°C, add 7 parts of γ-glycidyl etheroxypropyltrimethoxysilane and stir for 60 min. Then adjust the pH to 7.5 with a pH adjuster, perform vacuum degassing, filtration and discharge to obtain waterborne epoxy modified acrylic resin.

[0050] In step (A1), the emulsifier is composed of sodium dodecyl sulfate, fatty alcohol polyoxyethylene ether AEO-9, and allyloxynonylphenol polyoxyethylene ether ammonium sulfate SR-10 in a weight ratio of 4:3:1. In step (A2), the initiator is composed of ammonium persulfate and sodium bisulfite in a weight ratio of 3:1. In step (A3), the pH adjuster is 2-amino-2-methyl-1-propanol.

[0051] Furthermore, the filler is composed of nano-silica, nano-talc, and nano-barium sulfate in a weight ratio of 3:2:1. The particle size of the filler is 20-50 nm.

[0052] Furthermore, the silane coupling agent is composed of γ-methacryloxypropyltrimethoxysilane and γ-glycidoxypropyltrimethoxysilane in a weight ratio of 1:1.

[0053] Furthermore, the film-forming aid is composed of propylene glycol phenyl ether and dipropylene glycol butyl ether in a weight ratio of 1.5:1. The thickener is hydroxyethyl cellulose.

[0054] A method for preparing an environmentally friendly water-based varnish coating for printing includes the following steps:

[0055] (1) Add silane coupling agent and filler in proportion, stir and mix evenly to obtain filler pretreated with silane coupling agent;

[0056] (2) Add waterborne polyester resin, waterborne acrylic emulsion, waterborne epoxy modified acrylic resin and polyvinyl alcohol in proportion, and stir to mix evenly; then add filler, film-forming aid, thickener and defoamer pretreated with silane coupling agent, stir to mix evenly to obtain finished coating.

[0057] Furthermore, in step (1), silane coupling agent and filler are added in proportion, then acetic acid is added dropwise to adjust the pH to 4.5, the temperature is raised to 52°C, and the mixture is stirred for 30 minutes at a speed of 1200 rpm until it is uniformly mixed to obtain filler pretreated with silane coupling agent.

[0058] Furthermore, in step (2), waterborne polyester resin, waterborne acrylic emulsion, waterborne epoxy modified acrylic resin and polyvinyl alcohol are added in proportion and stirred at 800 rpm for 30 min. Then, filler, film-forming aid, thickener and defoamer pretreated with silane coupling agent are added and stirred at 1100 rpm for 30 min to obtain waterborne varnish coating.

[0059] Example 2

[0060] An environmentally friendly water-based varnish coating for printing comprises the following raw materials in parts by weight: 55 parts water-based polyester resin, 32 parts water-based acrylic emulsion, 23 parts water-based epoxy-modified acrylic resin, 12 parts filler, 5 parts silane coupling agent, 3 parts polyvinyl alcohol, 4 parts film-forming aid, 4 parts thickener, and 1.5 parts defoamer.

[0061] Furthermore, the filler is composed of nano-silica, nano-calcium carbonate, and nano-barium sulfate in a weight ratio of 3:2:1. The particle size of the filler is 20-50 nm.

[0062] Furthermore, the silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane.

[0063] Furthermore, the film-forming aid is composed of propylene glycol phenyl ether and dipropylene glycol butyl ether in a weight ratio of 1.6:1. The thickener is hydroxyethyl cellulose.

[0064] A method for preparing an environmentally friendly water-based varnish coating for printing includes the following steps:

[0065] (1) Add silane coupling agent and filler in proportion, stir and mix evenly to obtain filler pretreated with silane coupling agent;

[0066] (2) Add waterborne polyester resin, waterborne acrylic emulsion, waterborne epoxy modified acrylic resin and polyvinyl alcohol in proportion, and stir to mix evenly; then add filler, film-forming aid, thickener and defoamer pretreated with silane coupling agent, stir to mix evenly to obtain finished coating.

[0067] Furthermore, in step (1), silane coupling agent and filler are added in proportion, and then acetic acid is added dropwise to adjust the pH to 4.5, the temperature is raised to 52°C, and the mixture is stirred for 30 minutes at a speed of 1200 rpm until it is uniformly mixed to obtain filler pretreated with silane coupling agent.

[0068] Furthermore, in step (2), waterborne polyester resin, waterborne acrylic emulsion, waterborne epoxy modified acrylic resin and polyvinyl alcohol are added in proportion and stirred at 800 rpm for 30 min. Then, filler, film-forming aid, thickener and defoamer pretreated with silane coupling agent are added and stirred at 1100 rpm for 30 min to obtain waterborne varnish coating.

[0069] The rest of the content of this embodiment is the same as that of Embodiment 1, and will not be repeated here.

[0070] Example 3

[0071] An environmentally friendly water-based varnish coating for printing comprises the following raw materials in parts by weight: 50 parts water-based polyester resin, 30 parts water-based acrylic emulsion, 26 parts water-based epoxy-modified acrylic resin, 15 parts filler, 6 parts silane coupling agent, 3 parts polyvinyl alcohol, 4 parts film-forming aid, 4 parts thickener, and 1.5 parts defoamer.

[0072] Furthermore, the filler is composed of nano-silica, nano-talc powder, and nano-barium sulfate in a weight ratio of 3:1:1. The particle size of the filler is 20-50 nm.

[0073] Furthermore, the silane coupling agent is γ-glycidoxypropyltrimethoxysilane.

[0074] Furthermore, the film-forming aid is composed of propylene glycol phenyl ether and dipropylene glycol butyl ether in a weight ratio of 1.2:1. The thickener is hydroxyethyl cellulose.

[0075] A method for preparing an environmentally friendly water-based varnish coating for printing includes the following steps:

[0076] (1) Add silane coupling agent and filler in proportion, stir and mix evenly to obtain filler pretreated with silane coupling agent;

[0077] (2) Add waterborne polyester resin, waterborne acrylic emulsion, waterborne epoxy modified acrylic resin and polyvinyl alcohol in proportion, and stir to mix evenly; then add filler, film-forming aid, thickener and defoamer pretreated with silane coupling agent, stir to mix evenly to obtain finished coating.

[0078] Furthermore, in step (1), silane coupling agent and filler are added in proportion, and then acetic acid is added dropwise to adjust the pH to 4.5, the temperature is raised to 52°C, and the mixture is stirred for 30 minutes at a speed of 1200 rpm until it is uniformly mixed to obtain filler pretreated with silane coupling agent.

[0079] Furthermore, in step (2), waterborne polyester resin, waterborne acrylic emulsion, waterborne epoxy modified acrylic resin and polyvinyl alcohol are added in proportion and stirred at 800 rpm for 30 min. Then, filler, film-forming aid, thickener and defoamer pretreated with silane coupling agent are added and stirred at 1100 rpm for 30 min to obtain waterborne varnish coating.

[0080] The rest of the content of this embodiment is the same as that of Embodiment 1, and will not be repeated here.

[0081] Example 4

[0082] An environmentally friendly water-based varnish coating for printing and its preparation method, comprising the following raw materials in parts by weight: 48 parts of water-based polyester resin, 38 parts of water-based acrylic emulsion, 22 parts of water-based epoxy-modified acrylic resin, 13 parts of filler, 6 parts of silane coupling agent, 3 parts of polyvinyl alcohol, 4 parts of film-forming aid, 4 parts of thickener, and 1.5 parts of defoamer.

[0083] Furthermore, the filler is composed of nano-silica and nano-barium sulfate in a weight ratio of 3:2. The particle size of the filler is 20-50 nm.

[0084] Furthermore, the silane coupling agent is composed of γ-methacryloxypropyltrimethoxysilane and γ-glycidoxypropyltrimethoxysilane in a weight ratio of 1:1.

[0085] Furthermore, the film-forming aid is composed of propylene glycol phenyl ether and dipropylene glycol butyl ether in a weight ratio of 1.5:1. The thickener is hydroxyethyl cellulose.

[0086] A method for preparing an environmentally friendly water-based varnish coating for printing includes the following steps:

[0087] (1) Add silane coupling agent and filler in proportion, stir and mix evenly to obtain filler pretreated with silane coupling agent;

[0088] (2) Add waterborne polyester resin, waterborne acrylic emulsion, waterborne epoxy modified acrylic resin and polyvinyl alcohol in proportion, and stir to mix evenly; then add filler, film-forming aid, thickener and defoamer pretreated with silane coupling agent, stir to mix evenly to obtain finished coating.

[0089] Furthermore, in step (1), silane coupling agent and filler are added in proportion, and then acetic acid is added dropwise to adjust the pH to 4.5, the temperature is raised to 52°C, and the mixture is stirred for 30 minutes at a speed of 1200 rpm until it is uniformly mixed to obtain filler pretreated with silane coupling agent.

[0090] Furthermore, in step (2), waterborne polyester resin, waterborne acrylic emulsion, waterborne epoxy modified acrylic resin and polyvinyl alcohol are added in proportion and stirred at 800 rpm for 30 min. Then, filler, film-forming aid, thickener and defoamer pretreated with silane coupling agent are added and stirred at 1100 rpm for 30 min to obtain waterborne varnish coating.

[0091] Comparative Example 1

[0092] The difference between this comparative example and Example 1 is that the printing varnish coating of this comparative example comprises the following raw materials in parts by weight: 50 parts of waterborne polyester resin, 60 parts of waterborne acrylic emulsion, 12 parts of filler, 5 parts of silane coupling agent, 3 parts of polyvinyl alcohol, 4 parts of film-forming aid, 4 parts of thickener, and 1.5 parts of defoamer. The rest of the contents of this comparative example are the same as those of Example 1.

[0093] Comparative Example 2

[0094] The difference between this comparative example and Example 1 is that the preparation method of the waterborne epoxy-modified acrylic resin includes the following steps:

[0095] (A1) Take 100 parts of deionized water and 2 parts of emulsifier and mix them evenly; then add 29 parts of styrene, 24 parts of hydroxyethyl acrylate, 11 parts of glycidyl methacrylate and 3 parts of γ-methacryloyloxypropyltrimethoxysilane and stir at 1000 rpm for 60 min to obtain material A.

[0096] (A2) Take 15 parts of deionized water and 1 part of initiator and mix them evenly to prepare an initiator solution; take 40% of material A and 40% of the initiator solution and add them to the reactor, heat to 72°C under nitrogen protection and react for 40 min; then add the remaining material A and the remaining initiator solution dropwise over 4 h; after the dropwise addition is complete, heat to 92°C and then add 0.3 parts of tert-butyl hydrogen peroxide, keep warm for 60 min to obtain material B;

[0097] (A3) Material B was cooled to 45°C, and then the pH was adjusted to 7.5 using a pH adjuster. Vacuum degassing, filtration, and discharge were then performed to obtain waterborne epoxy-modified acrylic resin. The rest of this comparative example is the same as in Example 1.

[0098] The water-based varnishes of Examples 1-4 and Comparative Examples 1-2 were applied to the surface of printed corrugated paper, with a wet coating weight of 6 g / m². 2 The coating was dried with hot air at 70°C and 6 m / s for 60 seconds to form a water-based varnish coating. Performance tests were conducted on the environmentally friendly water-based varnish coatings for printing prepared in Examples 1-4 and Comparative Examples 1-2.

[0099] The adhesion test was conducted according to GB / T 9286-2021 using the cross-cut adhesion method, with a scratch spacing of 1 mm. After applying 3M 600 tape, it was quickly peeled off. The water contact angle was tested according to ASTM D7334-13. Abrasion resistance was tested according to ASTM D4060 using a Taber abrasion tester with a CS-10 wheel, a 500g load, and weight loss measured after 1000 revolutions. The ethanol wiping resistance test method was as follows: Ethanol-soaked nonwoven fabric was used to repeatedly wipe a 100mm area with 500g pressure and a back-and-forth motion every 2 seconds until the coating was damaged and discolored. The ambient temperature was 23℃. VOC content was tested according to GB 38507-2020.

[0100] The data test results are shown in the table below:

[0101]

[0102]

[0103] In the table above, the VOC content of Examples 1-4 and Comparative Examples 1-2 was found to be less than 30 g / L, but the adhesion, water contact angle, abrasion resistance and ethanol wiping resistance of Comparative Examples 1-2 all decreased to varying degrees.

[0104] In addition, folding resistance and color bursting tests were conducted on Examples 1-4 and Comparative Examples 1-2. The test method was as follows: the printing paper was placed on the crease of the crease machine and pressed down, and the sample was removed; the sample was folded back and forth 180° 8 times at the crease, and the degree of color bursting at the crease was observed and recorded. Examples 1-4 and Comparative Example 2 showed no color bursting or cracking, while Comparative Example 1 showed slight color bursting after 6 folds. The water-based varnish coating of Examples 1-4 was tested for 60° gloss according to GB / T 9754-2007, and the 60° gloss was measured to be 97-105 GU, which shows good gloss.

[0105] In summary, the environmentally friendly water-based varnish coating for printing of the present invention uses a combination of water-based polyester resin, water-based acrylic emulsion, and water-based epoxy-modified acrylic resin as the resin matrix, and is compounded with fillers and silane coupling agents, combined with film-forming aids, defoamers, and other additives. This improves the gloss and smoothness of the coating, and endows the water-based varnish coating with good abrasion resistance, solvent resistance, adhesion, hydrophobicity, and flexibility. It is environmentally friendly and can effectively protect printed materials during use, improving their durability and aesthetic appearance.

[0106] The specific embodiments described above are further illustrations of the technical solution and beneficial effects of the present invention, and are not intended to limit the implementation methods. For those skilled in the art, any obvious substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. An environmentally friendly water-based varnish coating for printing, characterized in that, The raw materials include the following parts by weight: 45-55 parts of waterborne polyester resin, 30-40 parts of waterborne acrylic emulsion, 22-32 parts of waterborne epoxy-modified acrylic resin, 5-15 parts of filler, 3-8 parts of silane coupling agent, 2-6 parts of polyvinyl alcohol, 2-8 parts of film-forming aid, 2-8 parts of thickener, and 0.5-3 parts of defoamer; wherein the silane coupling agent is at least one of γ-methacryloyloxypropyltrimethoxysilane and γ-glycidoxypropyltrimethoxysilane. The preparation method of the waterborne epoxy-modified acrylic resin includes the following steps: (A1) Take 100 parts of deionized water and 1-4 parts of emulsifier and mix them evenly; then add 20-30 parts of styrene, 15-25 parts of hydroxyethyl acrylate, 5-15 parts of glycidyl methacrylate, 4-8 parts of dodecafluoroheptyl methacrylate and 2-5 parts of γ-methacryloyloxypropyltrimethoxysilane and stir to obtain material A; (A2) Take 15 parts of deionized water and 0.5-1.5 parts of initiator and mix them evenly to prepare an initiator solution; take part of material A and part of the initiator solution and add them to the reaction vessel, and react under nitrogen protection; then add the remaining material A and the remaining initiator solution dropwise; after the dropwise addition is complete, raise the temperature to 90-95℃, and then add 0.1-0.4 parts of tert-butyl hydrogen peroxide, keep warm, and obtain material B; (A3) Cool down material B, add 5-10 parts of γ-glycidyl etheroxypropyltrimethoxysilane and stir to mix, then adjust the pH to 7.0-8.0 with a pH adjuster, perform vacuum degassing, filtration and discharge to obtain waterborne epoxy modified acrylic resin.

2. The environmentally friendly water-based varnish coating for printing according to claim 1, characterized in that, In step (A1), the emulsifier is at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, fatty alcohol polyoxyethylene ether, and allyloxynonylphenol polyoxyethylene ether ammonium sulfate.

3. The environmentally friendly water-based varnish coating for printing according to claim 1, characterized in that, In step (A2), the initiator is at least one of ammonium persulfate, potassium persulfate, and sodium bisulfite.

4. The environmentally friendly water-based varnish coating for printing according to claim 1, characterized in that, The filler is at least one of nano-silica, nano-calcium carbonate, nano-talc, and nano-barium sulfate.

5. The environmentally friendly water-based varnish coating for printing according to claim 1, characterized in that, The film-forming aid is at least one of dipropylene glycol butyl ether, propylene glycol phenyl ether, and dipropylene glycol methyl ether acetate.

6. The environmentally friendly water-based varnish coating for printing according to claim 1, characterized in that, The thickener is at least one of hydroxyethyl cellulose, hydroxypropyl methylcellulose, and methylcellulose.

7. The method for preparing the environmentally friendly water-based varnish coating for printing as described in any one of claims 1-6, characterized in that, Includes the following steps: (1) Add silane coupling agent and filler in proportion, stir and mix evenly to obtain filler pretreated with silane coupling agent; (2) Add waterborne polyester resin, waterborne acrylic emulsion, waterborne epoxy modified acrylic resin and polyvinyl alcohol in proportion, stir and mix evenly; then add filler, film-forming aid, thickener and defoamer pretreated with silane coupling agent, stir and mix evenly to obtain finished coating.

8. The method for preparing the environmentally friendly water-based varnish coating for printing according to claim 7, characterized in that: In step (2), waterborne polyester resin, waterborne acrylic emulsion, waterborne epoxy modified acrylic resin and polyvinyl alcohol are added in proportion and stirred at 500-1000 rpm for 20-60 min. Then, filler, film-forming aid, thickener and defoamer pretreated with silane coupling agent are added and stirred at 800-1200 rpm for 20-60 min to obtain waterborne varnish coating.

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