A packaging box printing process

Abstract

The application relates to the packaging box processing field and particularly discloses a packaging box printing process. The packaging box printing process comprises the following steps: S1: a pretreatment liquid is brushed on the surface of a packaging box to be printed for 10-15 minutes and then heated and dried, wherein the pretreatment liquid is prepared by mixing the following raw materials in parts by weight: 80-100 parts of water and 5-7 parts of water-soluble chitosan; S2: 50-70 parts of a connecting agent, 8-12 parts of pigment, 40-55 parts of water, 1-3 parts of polyether modified silicon defoaming agent, 1-3 parts of oleic acid amide and 10-15 parts of nano titanium dioxide are uniformly mixed to prepare water-based ink; and S3: the water-based ink is sprayed on a paper packaging box to be printed and dried. In addition, the printing process has the advantages that the water-based ink printed has good adhesion.

Description

Technical Field

[0001] This application relates to the field of packaging box processing, and more specifically, to a packaging box printing process. Background Technology

[0002] With the continuous progress of society and economy, the ink printing industry has gradually developed in my country. To this day, ink production technology and ink printing technology lead the development of major industries such as packaging, media and clothing. However, the raw materials for preparing inks in traditional technology contain a large amount of mineral oil. During the printing process or waste incineration, the mineral oil in the ink decomposes into a large amount of greenhouse gases such as carbon dioxide and fixed pollutants when heated. Furthermore, the substrates containing ink, such as cardboard and wood, are covered with insoluble oily chemical substances and are discarded in the soil, causing environmental pollution. Therefore, in order to make up for the shortcomings of traditional inks, water-based inks have been developed rapidly.

[0003] Water-based inks are water-based printing inks produced through chemical processes and physical mixing of binders, crosslinking agents, solvents, auxiliaries, pigments, and related additives. In recent years, the Chinese paper packaging box industry has placed greater emphasis on environmental protection, and water-based inks are ubiquitous in the paper packaging box printing field. However, due to the limitations of its material, water-based inks suffer from poor adhesion, making the printed graphics on paper packaging boxes prone to peeling off. Therefore, developing water-based inks with better adhesion is a technical challenge that needs to be solved in the field of paper packaging box printing. Summary of the Invention

[0004] In order to improve the adhesion of water-based inks to paper packaging boxes, this application provides a packaging box printing process.

[0005] This application provides a packaging box printing process, which adopts the following technical solution:

[0006] A packaging box printing process includes the following steps:

[0007] S1: Pre-treatment of the printing area of ​​the paper packaging box: Brush the pre-treatment liquid onto the surface of the printing area of ​​the packaging box for 10-15 minutes and then heat and dry it. The pre-treatment liquid is made by mixing the following raw materials in parts by weight: 80-100 parts water and 5-7 parts water-soluble chitosan.

[0008] S2: Preparation of water-based ink: Mix 50-70 parts of binder, 8-12 parts of pigment, 40-55 parts of water, 1-3 parts of polyether modified silicone defoamer, 1-3 parts of oleamide and 10-15 parts of nano titanium dioxide evenly to prepare water-based ink.

[0009] S3: Spraying ink: Spray water-based ink onto the area of ​​the paper packaging box to be printed, and then let it dry.

[0010] By adopting the above technical solution, the surface of the packaging box is first pretreated with a pretreatment liquid. The paper fibers on the surface of the packaging paper absorb water molecules in the pretreatment liquid, causing the paper fibers to swell. After drying, the gaps between the paper fibers increase, and the surface becomes rougher, increasing the adhesion between the paper surface and the ink. The chitosan macromolecules in the pretreatment liquid have good film-forming properties. The molecular chains have many positive charge centers and hydroxyl groups, which easily form electrostatic bonds and hydrogen bonds with the paper fibers. Therefore, the connection between the paper fibers is strong. Chitosan also has strong connectivity with the binders in water-based inks. Therefore, chitosan can effectively enhance the adhesion between the packaging box and the water-based ink layer. In addition, since the paper fibers will weaken to some extent after swelling and drying, the strength of the packaging box will decrease. Chitosan can also bridge between the paper fibers, enhancing the strength of the packaging box.

[0011] The nano-titanium dioxide in water-based inks has extremely high surface energy, enabling it to adsorb onto or into the crevices of pretreated rough paper fibers. It can also combine with the polar groups of chitosan, thereby enhancing the adhesion between the water-based ink layer and the packaging box. Nano-titanium dioxide can also fill the dried film-like network structure of the system, working in conjunction with the film-forming substances in the system to form an organic-inorganic network structure. This increases the film density and reduces the porosity of the dried ink layer and the packaging paper surface, further enhancing the adhesion between the water-based ink layer and the packaging box.

[0012] Preferably, the nano-titanium dioxide comprises the following modification steps:

[0013] S1: Mix nano-titanium dioxide with anhydrous ethanol evenly to prepare a dispersion with a mass fraction of 8-10%, and adjust the pH to 3-4; S2: Add trifluoropropyltrimethylsilane to the dispersion, heat to 60-80℃, stir at a constant temperature for 6-8 hours, filter, dry at 50-60℃ for 20-24 hours, grind to obtain modified nano-titanium dioxide, wherein the weight ratio of nano-titanium dioxide to trifluoropropyltrimethylsilane is (42-45):1.

[0014] By adopting the above technical solution, the nano-titanium dioxide was modified with trifluoropropyltrimethylsilane, which improved the compatibility between the nano-titanium dioxide and the ink system and enhanced the adhesion between the water-based ink layer and the packaging box.

[0015] Preferably, the pretreatment solution further includes 1-3 parts by weight of aqueous terpene resin.

[0016] By adopting the above technical solution, this application uses water-based terpene resin and chitosan in combination, which can exert a synergistic effect between them and significantly enhance the adhesion between the water-based ink layer and the packaging box.

[0017] Preferably, the mass ratio of the water-soluble chitosan to the water-based terpene resin is 6:(1.5-2.5).

[0018] By adopting the above technical solution, when the mass ratio of water-soluble chitosan to water-based terpene resin is 6:(1.5-2.5), the adhesion between the water-based ink layer and the packaging box is stronger.

[0019] Preferably, the binder comprises polyurethane acrylic emulsion, epoxy resin emulsion, and polyvinyl alcohol.

[0020] By adopting the above technical solutions, the polyurethane acrylic emulsion exhibits good compatibility with pigments and nano-titanium dioxide, and good adhesion to packaging cartons. The resulting ink has excellent printability, and the printed pattern is not easily detached. The epoxy resin emulsion contains highly active polar groups such as epoxy, hydroxyl, amine, and ester bonds, which have a strong bonding force with nano-titanium dioxide and the surface of packaging cartons. The polyvinyl alcohol molecular chain contains a large number of hydroxyl groups, exhibiting good film-forming properties and adhesion. The ink layer formed by the combination of polyurethane acrylic emulsion, epoxy resin emulsion, and polyvinyl alcohol has good adhesion to the packaging cartons.

[0021] Preferably, the mass ratio of the polyurethane acrylic emulsion, epoxy resin emulsion and polyvinyl alcohol is (4-6):(2-3):1.

[0022] By adopting the above technical solution, this application uses polyurethane acrylic emulsion, epoxy resin emulsion and polyvinyl alcohol in a specific mass ratio range, which can exert a synergistic effect and significantly enhance the adhesion between the water-based ink layer and the packaging box.

[0023] Preferably, the water-based ink also contains 8-10 parts by weight of fumed silica.

[0024] By adopting the above technical solution, fumed silica is one of the most important nano-scale inorganic raw materials. It has unique properties such as large specific surface area, strong surface adsorption force, large surface energy, and good dispersion performance. When used in combination with nano titanium dioxide, it can improve the adhesion between the ink layer and the packaging paper box.

[0025] Preferably, the water-based ink further includes 1-3 parts by weight of additives, the additives including aminosilane and epoxysilane, wherein the mass ratio of aminosilane to epoxysilane is (3-4):1.

[0026] By adopting the above technical solution, epoxy silane is a novel epoxy coupling agent with reactive groups. Amino silane has two functional groups, namely amino and ethoxy, of which three hydrolyzable groups (ethoxy) first hydrolyze to generate silanol in the reaction. Since silanol is unstable, it readily combines with nano titanium dioxide, fumed silica or the hydroxyl groups on the surface of packaging paper boxes for dehydration, thereby tightly bonding the packaging paper box with the ink layer. The amino group has two active hydrogens that can react with various polymers, thereby tightly bonding two materials with completely different properties through chemical bonds. The combined use of the two can further improve the adhesion of the ink layer.

[0027] In summary, this application has the following beneficial effects:

[0028] 1. First, a pretreatment solution is used to pretreat the surface of the packaging box. The paper fibers on the surface of the packaging paper absorb water molecules from the pretreatment solution, causing the paper fibers to swell. After drying, the gaps between the paper fibers increase, and the surface becomes rougher, increasing the adhesion between the paper surface and the ink. The chitosan macromolecules in the pretreatment solution have good film-forming properties. Their molecular chains have many positive charge centers and hydroxyl groups, which easily form electrostatic bonds and hydrogen bonds with the paper fibers, resulting in a strong connection between the chitosan and the paper fibers. Simultaneously, chitosan also has strong adhesion to the water-based ink layer, thus effectively enhancing the packaging. The adhesion between the paper box and the water-based ink layer; the nano-titanium dioxide in the water-based ink has extremely high surface energy, which can be adsorbed onto the rough paper fibers after pretreatment or into the gaps. At the same time, it can also combine with the polar groups of chitosan, thereby enhancing the adhesion between the water-based ink layer and the packaging box. The nano-titanium dioxide can also fill the dried film network structure of the system, and cooperate with the film-forming substances in the system to form an organic-inorganic network structure, which improves the density of the film and reduces the porosity of the dried ink layer and the surface of the packaging paper, thereby further enhancing the adhesion between the water-based ink layer and the packaging box.

[0029] 2. This application uses water-based terpene resin and chitosan in combination, which can exert a synergistic effect and significantly enhance the adhesion between the water-based ink layer and the packaging box;

[0030] 3. Epoxy silanes are novel epoxy coupling agents with reactive groups. Amino silanes have two functional groups, namely amino and ethoxy, of which three hydrolyzable groups (ethoxy) first hydrolyze to generate silanols in the reaction. Since silanols are unstable, they readily combine with and dehydrate the hydroxyl groups on the surface of nano titanium dioxide, fumed silica, or packaging paper boxes, thereby tightly bonding the packaging paper box with the ink layer. The amino group has two active hydrogens that can react with various polymers, thereby tightly bonding two materials with completely different properties through chemical bonds. The combined use of the two can further improve the adhesion of the ink layer. Detailed Implementation

[0031] Source of raw materials

[0032] Packaging boxes: The cardboard boxes used in the embodiments and test methods of this application are all from Renqiu Xingda Cardboard Box Factory;

[0033] Nano-titanium dioxide is from Nanjing Baoket New Materials Co., Ltd., model PT05;

[0034] Trifluoropropyltrimethylsilane is from Shanghai Yuanye Biotechnology Co., Ltd.;

[0035] The aminopropyltriethoxysilane was sourced from Qufu Jiaye Chemical New Materials Co., Ltd.

[0036] The water-soluble chitosan was sourced from Xi'an Shouhe Biotechnology Co., Ltd.

[0037] The water-based terpene resin and rosin resin are both from Jining Huakai Resin Co., Ltd.

[0038] The polyurethane acrylic emulsion is from Beijing Dechang Weiye Architectural Engineering Technology Co., Ltd.

[0039] Epoxy Resin Emulsion Bass Synthetic New Materials (Shenzhen) Co., Ltd.;

[0040] The polyvinyl alcohol was sourced from Guangzhou Zhonggao Chemical Co., Ltd., model number 2499.

[0041] The polyether-modified silicone defoamer is from Shenzhen Zhongherun Technology Co., Ltd., model ABC;

[0042] Oleamide is from Nantong Runfeng Petrochemical Co., Ltd., product number C0527;

[0043] The aminosilane is from Shandong Hengyu New Materials Co., Ltd., model KH602;

[0044] The epoxy silane is from Shenzhen Xinyi Plastics & Chemicals Co., Ltd., model Z6041;

[0045] Fumed silica is from Shanghai Kaiyin Chemical Co., Ltd., model AEROSIL150;

[0046] The present application will be further described in detail below with reference to preparation examples and embodiments.

[0047] Preparation Example

[0048] Preparation Example 1

[0049] Nano-titanium dioxide includes the following modification steps:

[0050] S1: Mix 4.2 kg of nano titanium dioxide with anhydrous ethanol to prepare a dispersion with a mass fraction of 8%, and adjust the pH to 3.

[0051] S2: Add 0.1 kg of trifluoropropyltrimethylsilane to the dispersion, heat to 60 °C, stir at a constant temperature for 6 h, filter, dry at 50 °C for 20 h, grind to obtain modified nano titanium dioxide.

[0052] Preparation Example 2

[0053] Nano-titanium dioxide includes the following modification steps:

[0054] S1: Mix 4.4 kg of nano-titanium dioxide with anhydrous ethanol to prepare a dispersion with a mass fraction of 9%, and adjust the pH to 3.5.

[0055] S2: Add 0.1 kg of trifluoropropyltrimethylsilane to the dispersion, heat to 70°C, stir at a constant temperature for 7 h, filter, dry at 55°C for 22 h, grind to obtain modified nano titanium dioxide.

[0056] Preparation Example 3

[0057] Nano-titanium dioxide includes the following modification steps:

[0058] S1: Mix 4.5 kg of nano titanium dioxide with anhydrous ethanol to prepare a dispersion with a mass fraction of 10%, and adjust the pH to 4.

[0059] S2: Add 0.1 kg of trifluoropropyltrimethylsilane to the dispersion, heat to 80 °C, stir at a constant temperature for 8 h, filter, dry at 60 °C for 24 h, grind to obtain modified nano titanium dioxide.

[0060] Preparation Example 4

[0061] The difference between Preparation Example 4 and Preparation Example 3 is that an equal amount of trifluoropropyltrimethylsilane was replaced with an equal amount of aminopropyltriethoxysilane, while the other steps were the same as in Preparation Example 3.

[0062] Example

[0063] Example 1

[0064] A packaging box printing process includes the following steps:

[0065] S1: Pre-treatment of the printing area of ​​the paper packaging box: The pre-treatment liquid is brushed onto the surface of the printing area of ​​the packaging box for 10 minutes and then heated and dried. The pre-treatment liquid is made by mixing the following raw materials in parts by weight: 80kg water, 5kg water-soluble chitosan and 1kg water-based terpene resin.

[0066] S2: Preparation of water-based ink: 50 kg of binder (28.57 kg of polyurethane acrylic emulsion, 14.29 kg of epoxy resin emulsion and 7.14 kg of polyvinyl alcohol; the mass ratio of polyurethane acrylic emulsion, epoxy resin emulsion and polyvinyl alcohol is 4:2:1), 8 kg of pigment, 40 kg of water, 1 kg of polyether modified silicone defoamer, 1 kg of oleamide, 1 kg of additives (0.75 kg of aminosilane and 0.25 kg of epoxy silane; the mass ratio of aminosilane and epoxy silane is 3:1), 8 kg of fumed silica and 10 kg of nano titanium dioxide are uniformly mixed to prepare water-based ink;

[0067] S3: Spraying ink: Spray water-based ink onto the area of ​​the paper packaging box to be printed, and then let it dry.

[0068] Example 2

[0069] A packaging box printing process includes the following steps:

[0070] S1: Pre-treatment of the printing area of ​​the paper packaging box: The pre-treatment liquid is brushed onto the surface of the printing area of ​​the packaging box for 12 minutes and then heated and dried. The pre-treatment liquid is made by mixing the following raw materials in parts by weight: 90kg water, 6kg water-soluble chitosan and 2kg water-based terpene resin.

[0071] S2: Preparation of water-based ink: 60 kg of binder (34.29 kg of polyurethane acrylic emulsion, 17.14 kg of epoxy resin emulsion and 8.57 kg of polyvinyl alcohol; the mass ratio of polyurethane acrylic emulsion, epoxy resin emulsion and polyvinyl alcohol is 4:2:1), 10 kg of pigment, 48 kg of water, 2 kg of polyether modified silicone defoamer, 2 kg of oleamide, 2 kg of additives (1.5 kg of aminosilane and 0.5 kg of epoxy silane; the mass ratio of aminosilane and epoxy silane is 3:1), 9 kg of fumed silica and 12 kg of nano titanium dioxide are uniformly mixed to prepare water-based ink;

[0072] S3: Spraying ink: Spray water-based ink onto the area of ​​the paper packaging box to be printed, and then let it dry.

[0073] Example 3

[0074] A packaging box printing process includes the following steps:

[0075] S1: Pre-treatment of the printing area of ​​the paper packaging box: The pre-treatment liquid is brushed onto the surface of the printing area of ​​the packaging box for 15 minutes and then heated and dried. The pre-treatment liquid is made by mixing the following raw materials in parts by weight: 100kg water, 7kg water-soluble chitosan and 3kg water-based terpene resin.

[0076] S2: Preparation of water-based ink: 70 kg of binder (40 kg of polyurethane acrylic emulsion, 20 kg of epoxy resin emulsion and 10 kg of polyvinyl alcohol; the mass ratio of polyurethane acrylic emulsion, epoxy resin emulsion and polyvinyl alcohol is 4:2:1), 12 kg of pigment, 55 kg of water, 3 kg of polyether modified silicone defoamer, 3 kg of oleamide, 3 kg of additives (2.25 kg of aminosilane and 0.75 kg of epoxy silane; the mass ratio of aminosilane and epoxy silane is 3:1), 10 kg of fumed silica and 15 kg of nano titanium dioxide are uniformly mixed to prepare water-based ink;

[0077] S3: Spraying ink: Spray water-based ink onto the area of ​​the paper packaging box to be printed, and then let it dry.

[0078] Example 4

[0079] The difference between Example 4 and Example 2 is that the nano-titanium dioxide was modified, and the modified nano-titanium dioxide came from Preparation Example 1. The remaining steps were the same as in Example 2.

[0080] Example 5

[0081] The difference between Example 5 and Example 4 is that the modified nano-titanium dioxide was derived from Preparation Example 2, while the remaining steps were the same as in Example 4.

[0082] Example 6

[0083] The difference between Example 6 and Example 4 is that the modified nano-titanium dioxide was derived from Preparation Example 3, while the remaining steps were the same as in Example 4.

[0084] Example 7

[0085] The difference between Example 7 and Example 4 is that the modified nano-titanium dioxide was derived from Example 4, while the remaining steps were the same as in Example 4.

[0086] Example 8

[0087] The difference between Example 8 and Example 5 is that no aqueous terpene resin was added, while the rest of the steps were the same as in Example 5.

[0088] Example 9

[0089] The difference between Example 9 and Example 5 is that the aqueous terpene resin is replaced with rosin resin, while the other steps are the same as in Example 5.

[0090] Example 10

[0091] The difference between Example 10 and Example 5 is that the mass of the aqueous terpene resin is 1.5 kg, the mass ratio of water-soluble chitosan to aqueous terpene resin is 6:1.5, and the remaining steps are the same as in Example 5.

[0092] Example 11

[0093] The difference between Example 11 and Example 5 is that the mass of the aqueous terpene resin is 2.5 kg, the mass ratio of water-soluble chitosan to aqueous terpene resin is 6:2.5, and the remaining steps are the same as in Example 5.

[0094] Example 12

[0095] The difference between Example 12 and Example 5 is that the mass of the aqueous terpene resin is 2.7 kg, the mass ratio of water-soluble chitosan to aqueous terpene resin is 6:2.7, and the remaining steps are the same as in Example 5.

[0096] Example 13

[0097] The difference between Example 13 and Example 5 is that the mass of the aqueous terpene resin is 1.3 kg, the mass ratio of water-soluble chitosan to aqueous terpene resin is 6:1.3, and the remaining steps are the same as in Example 5.

[0098] Examples 14-18

[0099] The difference between Examples 14-18 and Example 5 is that the mass ratio of polyurethane acrylic emulsion, epoxy resin emulsion and polyvinyl alcohol is different. In Example 5, the mass ratio of polyurethane acrylic emulsion, epoxy resin emulsion and polyvinyl alcohol is 4:2:1, and the binder is 60 kg.

[0100] Table 1. Mass and mass ratio of polyurethane acrylic emulsion, epoxy resin emulsion, and polyvinyl alcohol in Examples 14-18.

[0101]

[0102] Example 19

[0103] The difference between Example 19 and Example 14 is that no fumed silica was added, while the other steps are the same as in Example 14.

[0104] Example 20

[0105] The difference between Example 20 and Example 14 is that fumed silica is replaced with nano zinc oxide, while the rest of the steps are the same as in Example 14.

[0106] Example 21

[0107] The difference between Example 21 and Example 14 is that the mass of aminosilane is 1.56 kg, the mass of epoxysilane is 0.44 kg, and the mass ratio of aminosilane to epoxysilane is 3.5:1. All other steps are the same as in Example 14.

[0108] Example 22

[0109] The difference between Example 22 and Example 14 is that the mass of aminosilane is 1.6 kg, the mass of epoxysilane is 0.4 kg, and the mass ratio of aminosilane to epoxysilane is 4:1. All other steps are the same as in Example 14.

[0110] Example 23

[0111] The difference between Example 23 and Example 14 is that the mass of aminosilane is 1.47 kg, the mass of epoxysilane is 0.53 kg, and the mass ratio of aminosilane to epoxysilane is 2.8:1. All other steps are the same as in Example 14.

[0112] Example 24

[0113] The difference between Example 24 and Example 14 is that the mass of aminosilane is 1.52 kg, the mass of epoxysilane is 0.48 kg, and the mass ratio of aminosilane to epoxysilane is 3.2:1. All other steps are the same as in Example 14.

[0114] Comparative Example

[0115] Comparative Example 1

[0116] The difference between Comparative Example 1 and Example 21 is that no pretreatment step was performed on the area of ​​the paper packaging box to be printed; all other steps were the same as in Example 21.

[0117] Comparative Example 2

[0118] The difference between Comparative Example 2 and Example 21 is that water-soluble chitosan and water-based terpene resin were not added, while the rest of the steps were the same as in Example 21.

[0119] Comparative Example 3

[0120] The difference between Comparative Example 3 and Example 21 is that no water-soluble chitosan was added, while the rest of the steps were the same as in Example 21.

[0121] Comparative Example 4

[0122] The difference between Comparative Example 4 and Example 21 is that an equal amount of water-soluble chitosan was replaced with an equal amount of polyvinyl alcohol, while the rest of the steps were the same as in Example 21.

[0123] Comparative Example 5

[0124] The difference between Comparative Example 5 and Example 21 is that nano-titanium dioxide is replaced with nano-zinc oxide, while the rest of the steps are the same as in Example 21.

[0125] Performance testing

[0126] Detection methods

[0127] Ink adhesion test: The inks printed on packaging boxes using the printing methods of Examples 1-24 and Comparative Examples 1-5 were tested for adhesion according to standard GB / T13217.7-2009. The substrate was a paper packaging box.

[0128] Peel strength test: The peel strength of the water-based ink layer was tested according to the standard GB / T26394-2011. The substrate was a paper packaging box with a thickness of 0.04mm.

[0129] Table 2. Adhesion and peel strength test results of inks printed on packaging boxes using the printing methods of Examples 1-24 and Comparative Examples 1-5.

[0130]

[0131]

[0132] As shown in Table 1, the ink adhesion of the printing process in Examples 1-3 of this application on the packaging paper box can reach 92%, and the peel force can reach more than 1.8N / 15mm, indicating that the printing method of this application has good ink adhesion on the packaging paper box.

[0133] Based on the data in Table 1, Example 2, and Examples 4-7, it can be seen that the modification of nano-titanium dioxide with trifluoropropyltrimethylsilane effectively improves the adhesion between ink and packaging paper. Furthermore, the modified nano-titanium dioxide prepared in Example 2, when added to water-based ink, results in better adhesion of the water-based ink. In addition, compared with the modification of nano-titanium dioxide using other silane coupling agents, the modification of nano-titanium dioxide using trifluoropropyltrimethylsilane in this application results in better compatibility between nano-titanium dioxide and the system, and also better adhesion of the water-based ink.

[0134] Based on the data in Table 1, Example 5, and Examples 8-9, it can be seen that adding terpene resin to the pretreatment solution in this application can effectively improve the adhesion between ink and packaging paper box;

[0135] Based on the data in Table 1, Example 5, and Examples 10-13, it can be seen that when the mass ratio of water-soluble chitosan to water-based terpene resin is 6:(1.5-2.5), the adhesion between the water-based ink layer and the packaging box is stronger. This application further controls the weight ratio of water-soluble chitosan to water-based terpene resin, which can further promote the synergistic effect of the two, thereby further enhancing the adhesion between the water-based ink layer and the packaging box.

[0136] Based on the data in Table 1, Example 5, and Examples 14-18, it can be seen that the inks in Examples 5 and 14-15 have strong adhesion. This indicates that by further controlling the mass ratio of polyurethane acrylic emulsion, epoxy resin emulsion, and polyvinyl alcohol in this application, and keeping the mass ratio of polyurethane acrylic emulsion, epoxy resin emulsion, and polyvinyl alcohol within the range of (4-6):(2-3):1, the adhesion between the water-based ink layer and the packaging box can be significantly enhanced.

[0137] Based on the data in Table 1, Example 14, and Examples 19-20, it can be seen that the combined use of fumed silica and nano-titanium dioxide can improve the adhesion between the ink layer and the packaging paper box. The same effect cannot be achieved when other nanoparticles are used in combination with nano-titanium dioxide.

[0138] Based on the data in Table 1, Example 14, and Examples 21-24, it can be seen that when the aminosilane and epoxysilane added in this application are used in combination, and the mass ratio of aminosilane to epoxysilane is (3-4):1, the adhesion of the ink can be effectively improved.

[0139] Based on the data from Comparative Examples 1-5 and Example 14, it can be seen that the pretreatment solution prepared in this application can significantly increase the adhesion between the packaging paper box and the ink. The pretreatment solution of this application uses water, chitosan, and terpene resin to roughen the surface of the packaging paper box. At the same time, chitosan and terpene resin synergistically increase various functional groups on the surface of the packaging paper box, thereby enhancing the adhesion between the water-based ink layer and the packaging box. In addition, the nano-titanium dioxide in the water-based ink, in conjunction with the pretreatment step, adsorbs onto the rough paper fibers or into the gaps after pretreatment. It can also combine with chitosan to enhance the adhesion between the water-based ink layer and the packaging box. The nano-titanium dioxide can also fill the dried film network structure of the system, combining with the film-forming substances in the system to form an organic-inorganic network structure, which improves the film density and reduces the porosity of the dried ink layer and the packaging paper surface, thereby further enhancing the adhesion between the water-based ink layer and the packaging box.

[0140] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A packaging box printing process, characterized in that: Includes the following steps: S1: Pre-treatment of the printing area of ​​the paper packaging box: The pre-treatment liquid is brushed onto the surface of the printing area of ​​the packaging box for 10-15 minutes and then heated and dried. The pre-treatment liquid is made by mixing the following raw materials in parts by weight: 80-100 parts water, 5-7 parts water-soluble chitosan, and 1-3 parts water-based terpene resin; the mass ratio of the water-soluble chitosan to the water-based terpene resin is 6:(1.5-2.5). S2: Preparation of water-based ink: Mix 50-70 parts of binder, 8-12 parts of pigment, 40-55 parts of water, 1-3 parts of polyether modified silicone defoamer, 1-3 parts of oleamide and 10-15 parts of nano titanium dioxide evenly to prepare water-based ink. S3: Spraying ink: Spraying water-based ink onto the area of ​​the paper packaging box to be printed, and then drying; The binder comprises polyurethane acrylic emulsion, epoxy resin emulsion and polyvinyl alcohol; the mass ratio of the polyurethane acrylic emulsion, epoxy resin emulsion and polyvinyl alcohol is (4-6):(2-3):1; The water-based ink also includes 1-3 parts by weight of additives, the additives including aminosilane and epoxysilane, the mass ratio of aminosilane to epoxysilane being (3-4):1; The nano-titanium dioxide comprises the following modification steps: S11: Mix nano-titanium dioxide with anhydrous ethanol evenly to prepare a dispersion with a mass fraction of 8-10%, and adjust the pH to 3-4. S21: Add trifluoropropyltrimethylsilane to the dispersion, heat to 60-80℃, stir at a constant temperature for 6-8h, filter, dry at 50-60℃ for 20-24h, grind to obtain modified nano titanium dioxide, wherein the weight ratio of nano titanium dioxide to trifluoropropyltrimethylsilane is (42-45):

1.

2. The packaging box printing process according to claim 1, characterized in that: The water-based ink also contains 8-10 parts by weight of fumed silica.

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