Water-based high-gloss wear-resistant gravure ink and preparation method thereof

Abstract

The invention relates to the field of water-based ink preparation, in particular to water-based high-gloss wear-resistant gravure ink and a preparation method thereof. According to the ink, functional BN nanosheets modified by an organic silicon coupling agent and an IB copolymer containing an epoxy structure are adopted, and a compact cross-linked network is formed, so that high gloss, excellent wear resistance, strong adhesion, high initial dryness and excellent water resistance are realized. Compared with the prior art, the glossiness of the ink is improved by about 20%, the wear-resistant cycle index is remarkably increased, the adhesive force reaches the optimal level 5, and the initial dryness and the water resistance are greatly improved. The ink is suitable for high-requirement packaging and printing of food, beverage, medicine and the like, and has the advantages of environmental protection and stable quality.

Description

Technical Field

[0001] The invention relates to the field of water-based ink preparation, in particular to a water-based high-gloss abrasion-resistant gravure ink and a preparation method thereof. Background Art

[0002] Existing gravure printing inks are mainly solvent-based or alcohol-soluble, which have excellent performance in printing effect, abrasion resistance, adhesion, etc. However, because they contain a large amount of volatile organic compounds (VOC), they are easy to cause environmental pollution and safety hazards when used in packaging fields with high safety and environmental protection requirements such as food, beverages, medicines, and health products. For this reason, water-based inks have gradually attracted attention for their low VOC, environmental protection, and easy cleaning advantages, and are regarded as an important development direction to replace traditional solvent-based inks.

[0003] However, existing water-based inks still have certain defects in terms of high gloss, abrasion resistance and printing adaptability. The high surface tension of water in the water-based system makes the ink prone to problems such as insufficient wetting, slow drying, low film adhesion and insufficient mechanical strength during film formation, resulting in printed products prone to shedding, wear, color difference and unclear patterns. In addition, although conventional modification methods can improve the film-forming and abrasion resistance of inks to a certain extent, it is often difficult to strike a balance between high gloss and abrasion resistance.

[0004] The Chinese invention patent (publication number: CN101054489A, publication date: 2007-10-17) water-based high-gloss wear-resistant gravure ink is made by mixing acrylic resin, acrylic emulsion, pigment, ethanol, fastener, dispersant, deionized water, water-based emulsified wax, defoamer, and leveling agent. The product of the invention fully meets the requirements of gravure printing ink, has stable quality, and can replace solvent-based gravure ink; however, the product still needs to be further improved in terms of wear resistance and adhesion.

[0005] In recent years, with the development of nanotechnology, nanomaterials have been gradually introduced into ink formulations as functional additives to improve the overall performance of inks. Among them, boron nitride (BN) nanosheets are considered to be potential materials for improving the abrasion resistance and adhesion of inks due to their excellent mechanical strength, thermal stability and chemical inertness. However, the hydrophobicity and agglomeration of BN nanosheets themselves make them less dispersible in aqueous systems. Direct addition can easily lead to uneven dispersion of inks, thus affecting the printing effect. Summary of the invention

[0006] In order to solve the above-mentioned technical problems, the purpose of the present invention is to provide a water-based high-gloss and abrasion-resistant gravure ink. By simultaneously introducing functionalized boron nitride nanosheets and ethylene-methacrylate glycidyl copolymer with an epoxy structure into the water-based ink, not only the shortcomings of the water-based ink in drying, film formation and abrasion resistance are effectively overcome, but also the organic combination of high gloss, excellent adhesion and abrasion resistance is achieved, meeting the application needs in the packaging printing field with extremely high requirements on safety, environmental protection and printing quality.

[0007] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions: A water-based high-gloss and abrasion-resistant gravure ink, which comprises the following components by weight percentage: Acrylic resin 10%~20%, Soft film-forming acrylic emulsion 30%~45%, Pigment 8% to 12%, Water-based emulsified wax 2% to 5%, Ethylene-glycidyl methacrylate copolymer 1.0%~5.0%, Functionalized boron nitride nanosheets 0.1%~1.0%, Ethanol 5% to 20%, Deionized water 10%~20%; The acrylic resin is modified by amination, and the functionalized boron nitride nanosheets are prepared by modifying the boron nitride nanosheets with an organic silicon coupling agent.

[0008] Preferably, the ink comprises the following components: Acrylic resin 12%~18%, Soft film-forming acrylic emulsion 35%~40%, Pigment 8% to 12%, Water-based emulsified wax 2% to 5%, Ethylene-glycidyl methacrylate copolymer 1.5% to 3.0%, Functionalized boron nitride nanosheets 0.2% to 0.8%, Ethanol 9% to 14%, Deionized water 12%~16%.

[0009] Preferably, the acrylic resin is J-678 acrylic resin produced by BASF Shanghai, the soft film-forming acrylic emulsion is RT-5300 produced by Beijing Lijiaqiao Chuangzhan Chemical Co., Ltd., and the ethylene-glycidyl methacrylate copolymer is Igetabond™ (IB) produced by Sumitomo Chemical.

[0010] Preferably, the pigment is selected from Lithol Scarlet 335, Golden Red 258, titanium dioxide, phthalocyanine green or phthalocyanine blue for ink.

[0011] Preferably, the ink further comprises 3% to 10% of a pH stabilizer, 0.2% to 0.6% of a dispersant, 0.3% to 0.6% of a defoamer and 0.3% to 0.6% of a leveling agent.

[0012] Preferably, the pH stabilizer is an amine or an amine compound, the dispersant is a titanate dispersant, the defoamer is an organosilicon defoamer, and the leveling agent is an organosilicon leveling agent.

[0013] Preferably, the amount of the organosilicon coupling agent in the functionalized boron nitride nanosheets is 0.5% to 2% of the weight of the boron nitride nanosheets; the organosilicon coupling agent is selected from one of 3-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, glycerylpropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane.

[0014] As a further preferred embodiment, the preparation method of the functionalized boron nitride nanosheets is as follows: 1) Weigh an appropriate amount of boron nitride nanosheets and add them to an appropriate amount of anhydrous ethanol or isopropanol; use an ultrasonic processor to perform ultrasonic treatment for 30 to 60 minutes until a uniform and stable BN nanosheet dispersion is obtained; 2) In another container, dissolve 0.5% to 2% of 3-aminopropyltriethoxysilane in anhydrous ethanol and stir evenly; 3) Slowly add the 3-aminopropyltriethoxysilane solution to the boron nitride nanosheet dispersion to keep the system uniformly mixed; under the protection of inert gas, place the mixed solution in a reactor with a reflux device, heat to about 80°C to 90°C, and react for 3-4 hours; after the reaction is completed, cool the reaction system to room temperature; 4) separating the functionalized boron nitride nanosheets by centrifugation or filtration, and washing them with anhydrous ethanol or deionized water for multiple times to remove unreacted 3-aminopropyltriethoxysilane and by-products; finally, drying the washed boron nitride nanosheets at 60° C. to 80° C. to obtain boron nitride nanosheets functionalized with 3-aminopropyltriethoxysilane.

[0015] Furthermore, the present invention also provides a method for preparing the ink, the method comprising the following steps: (a) Amination procedure: In a reaction kettle equipped with a stirring device, after mixing part of the deionized water and the pH stabilizer, slowly add the acrylic resin while stirring, and fully dissolve it at 70°C to 90°C to form an aminated modified acrylic resin liquid; (b) Dispersion pretreatment: The aminated resin liquid, ethanol, part of the defoamer, ethylene-glycidyl methacrylate copolymer, functionalized boron nitride nanosheets, dispersant and pigment are added to a dispersion device according to the formula ratio, and after being fully stirred, the mixture is transferred to a sand mill for sand grinding until the ink fineness reaches ≤20 μm; (c) Mixing and dispersion procedure: The sand-milled color paste is transferred into a slurry mixing barrel, and soft film-forming acrylic emulsion, water-based emulsified wax, leveling agent, remaining defoaming agent and deionized water are gradually added at a certain stirring speed. After low-speed stirring, sampling is performed to test whether it meets the technical indicators, and then the ink is filtered and packaged.

[0016] Preferably, the sand grinding step is repeated 2 to 3 times to ensure that the ink fineness is stably controlled at 20 μm or less.

[0017] The present invention adopts the above-mentioned technical solution, introduces functionalized boron nitride nanosheets modified by an organosilicon coupling agent and ethylene-glycidyl methacrylate copolymer (Igetabond™ (IB)) with an epoxy structure, and achieves the following significant technical effects: 1. Excellent abrasion resistance and mechanical strength: By using silicone coupling agent to functionalize boron nitride nanosheets, its dispersibility and interfacial compatibility in ink are improved, so that it can partially copolymerize with acrylic resin and other components to form a strong interpenetrating network structure, thereby significantly improving the abrasion resistance and adhesion of the ink, ensuring that the printed pattern remains intact and clear for a long time.

[0018] 2. Significantly improved adhesion: The present invention also introduces ethylene-glycidyl methacrylate copolymer, in which Sumitomo Chemical's Igetabond™ (IB) is used as the copolymer. IB is copolymerized by ethylene and glycidyl methacrylate (E-GMA), and contains epoxy groups in its molecules. These epoxy groups give IB excellent reactivity, and can react chemically with hydroxyl, amino or carboxyl groups in a variety of materials to form stable covalent bonds or cross-linked structures, thereby significantly improving the adhesion and overall mechanical strength between the ink and the printed substrate, significantly improving the adhesion performance of the printed product, and preventing peeling and shedding.

[0019] 3. High gloss and excellent film-forming properties: The amine-modified acrylic resin and the soft film-forming acrylic emulsion work synergistically to ensure that the ink has good leveling and uniformity during the film-forming process. The final ink film has high gloss and bright colors, meeting the requirements of high-end packaging printing.

[0020] 4. Environmental protection and safety: The present invention adopts a water-based system, which significantly reduces the emission of volatile organic compounds (VOCs). At the same time, the components are optimized to achieve low-toxic, low-pollution green and environmentally friendly inks, which are suitable for packaging fields with high safety requirements such as food, beverages, medicines, and health products.

[0021] 5. Stable storage and printing adaptability: The synergistic effect of each component makes the ink less likely to stratify, precipitate and dry out during storage. At the same time, it can maintain stable initial drying and printing adaptability during high-speed printing, further improving production efficiency and economic benefits.

[0022] In summary, the water-based high-gloss and abrasion-resistant gravure ink provided by the present invention has high gloss, abrasion resistance, strong adhesion, environmental protection and safety, and good printing adaptability, which significantly solves the shortcomings of existing water-based inks in drying, film formation, abrasion resistance and adhesion, and has broad application prospects. DETAILED DESCRIPTION

[0023] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0024] The present invention uses 3-aminopropyltriethoxysilane (APTES) as an example of a specific functionalization method, which can be used to perform organosilicon functionalization treatment on boron nitride nanosheets, thereby improving their compatibility and interfacial bonding strength with the polymer system: 1. Dispersion of BN nanosheets: Weigh an appropriate amount of boron nitride nanosheets (BN), add it to an appropriate amount of anhydrous ethanol or isopropanol, and perform ultrasonic treatment for 50 minutes using an ultrasonic processor until a uniform and stable BN nanosheet dispersion is obtained.

[0025] 2. Preparation of coupling agent solution: In another container, dissolve 3-aminopropyltriethoxysilane (APTES) in anhydrous ethanol at the desired ratio (usually 1.0% of the weight of BN nanosheets). After stirring evenly, let it stand for a few minutes to ensure that APTES is fully dissolved.

[0026] 3. Functionalization reaction: Slowly add the APTES solution to the BN nanosheet dispersion to keep the system uniformly mixed. Under the protection of an inert gas (such as nitrogen), place the mixed solution in a reactor with a reflux device, heat to about 85°C, and react for about 4 hours.

[0027] During the reaction, the ethoxy groups in the APTES molecules hydrolyze to form silanols, which then undergo condensation reactions with hydroxyl groups or defect sites that may exist on the surface of the BN nanosheets to form Si-OB bonds, thereby fixing the organic silicon segments on the BN surface.

[0028] 4. Post-processing: After the reaction is completed, the reaction system is cooled to room temperature. The functionalized BN nanosheets are separated by centrifugation or filtration, and washed with anhydrous ethanol or deionized water for multiple times to remove unreacted APTES and byproducts. Finally, the washed BN nanosheets are dried at 60°C to 80°C to obtain BN nanosheets functionalized with APTES.

[0029] The formula raw materials of the embodiments of the present invention and the comparative examples are shown in Table 1 and Table 2, and the ink preparation method is as follows: 1. Raw material preparation and amination treatment Accurately weigh each component according to the requirements of each formula. First, place the aminated modified acrylic resin, part of the deionized water and the pH stabilizer (amine compound) in a reaction kettle, heat to 70℃~90℃ and continue stirring until the resin is completely dissolved to form a uniform aminated resin liquid.

[0030] 2. Dispersion and sand grinding The aminated resin liquid, ethanol, part of the defoamer (total amount 60%), ethylene-methyl glycidyl methacrylate copolymer (IB or its substitute), functionalized boron nitride nanosheets (or non-functionalized BN or no BN in the comparative example), dispersant and pigment are added to a dispersing device according to their respective proportions, and after pre-dispersion by high-speed stirring, the mixture is transferred to a sand mill for grinding until the ink fineness is controlled within ≤20μm.

[0031] 3. Post-mixing and packaging Transfer the sanded color paste into the slurry mixing barrel, and gradually add the soft film-forming acrylic emulsion, water-based emulsified wax, leveling agent, remaining defoaming agent and deionized water at a certain stirring speed. After low-speed uniform mixing, sample and test all indicators to meet the requirements, and then filter and package for storage.

[0032] Table 1 Formula of each component in the embodiment (%) Table 2 Comparative Example Components (%) in: The aminated modified acrylic resin uses J-678 acrylic resin from BASF Shanghai; The soft film-forming acrylic emulsion adopts RT-5300 from Beijing Lijiaqiao Chuangzhan Chemical Co., Ltd.; IB copolymer uses Sumitomo Chemical's Igetabond™ (IB); Conventional copolymers use conventional methacrylic acid polymers; The pigment used is Lithol Red 335; Non-functionalized BN uses conventional BN nanosheets, provided by Suzhou Napu Material Technology Co., Ltd. The water-based emulsified wax, pH stabilizer, dispersant, defoamer and leveling agent are the same as those in the Chinese invention patent (publication number: CN101054489A, publication date: 2007-10-17), and commercially available conventional ink additives are selected.

[0033] 4. Printing and performance testing Printing tests were conducted on polyethylene films using a standard gravure printer. After the ink was completely dry, the surface gloss was measured using a 60° gloss meter; the dry grinding tester was used to test the number of dry grinding anti-friction cycles (in cycles); and the cross-hatch method was used to evaluate adhesion (level 5 is the best). Each test was repeated three times under the same environmental conditions and the average value was taken. Comparative Example 5 is the experimental data of Example 1 of the Chinese invention patent (publication number: CN101054489A, publication date: 2007-10-17).

[0034] The test data is summarized in Table 3: Table 3 Test data of embodiments and comparative examples 5. Data analysis and technical effect description According to the analysis of the data in Table 3, the following conclusions can be drawn, showing that the embodiments of the present invention are far superior to the comparative samples in various performance indicators, thereby proving the significant advantages of the technical solution of the present invention.

[0035] First, in terms of glossiness, the test values ​​of the examples are between 76% and 80%, while the glossiness of the comparative samples is around 62% to 64%, with an average increase of about 20%. This shows that the formula of the present invention can obtain a more uniform and smooth ink film, making the printed pattern brighter and having a high gloss effect.

[0036] Secondly, in terms of dry abrasion resistance cycles, the average number of cycles of the embodiment is about 125, while the number of cycles of the comparative sample is about 104 to 108, and the comparative example 5 is only 97. The wear resistance of the embodiment is improved by about 20%, which means that in the actual printing process, the ink film formed by the ink has stronger anti-friction ability, which can significantly extend the service life of the printed product.

[0037] Third, in terms of adhesion, all embodiments reached level 5 (optimal state), while the adhesion of the comparative samples was between level 4 and 4.5, indicating that the embodiments had better bonding effect between the ink film and the printed substrate, and the printed products were less likely to fall off or peel off.

[0038] In addition, in the initial drying test, the initial drying of the ink of the embodiment is between 37 and 39 mm, while that of the comparative sample is about 30 to 32 mm. Higher initial drying helps to improve printing efficiency and pattern quality and reduce printing defects caused by uneven drying.

[0039] In terms of water resistance, the ink of the example shows super strong water resistance of 225 to 230 hours, while the comparative sample only shows about 148 to 155 hours. The significant improvement in water resistance further proves the significant advantages of the example in terms of weather resistance and chemical resistance, which is conducive to the long-term stability of printed products in harsh environments.

[0040] In summary, the embodiments of the present invention are far superior to the comparative samples and the existing technologies in the literature in key properties such as gloss, abrasion resistance, adhesion, initial drying, water resistance and ink fineness, which fully demonstrates the technological breakthrough brought about by the synergistic effect of functionalized BN nanosheets modified with silicone coupling agents and IB copolymers containing epoxy structures, and provides a green, environmentally friendly and high-performance ink for high-end packaging printing.

[0041] In summary, by adjusting the formula of each component and conducting comparative tests, the results fully prove that the simultaneous use of functionalized BN nanosheets modified with silicone coupling agents and IB copolymers containing epoxy structures can significantly improve the gloss, abrasion resistance and adhesion of water-based inks, meeting the strict requirements of high-end packaging printing for environmental protection and durability.

Claims

1. A water-based high-gloss and abrasion-resistant gravure ink, characterized in that: The ink comprises the following components by weight percentage: Acrylic resin 10%~20%, Soft film-forming acrylic emulsion 30%~45%, Pigment 8% to 12%, Water-based emulsified wax 2% to 5%, Ethylene-glycidyl methacrylate copolymer 1.0%~5.0%, Functionalized boron nitride nanosheets 0.1% to 1.0%, Ethanol 5% to 20%, Deionized water 10%~20%; The acrylic resin is prepared by using an aminated modified acrylic resin, and the functionalized boron nitride nanosheets are prepared by using an organic silicon coupling agent to modify the boron nitride nanosheets.

2. The water-based high-gloss and abrasion-resistant gravure ink according to claim 1, characterized in that: The ink comprises the following components: Acrylic resin 12%~18%, Soft film-forming acrylic emulsion 35%~40%, Pigment 8% to 12%, Water-based emulsified wax 2% to 5%, Ethylene-methacrylate glycidyl copolymer 1.5% to 3.0%, Functionalized boron nitride nanosheets 0.2% to 0.8%, Ethanol 9% to 14%, Deionized water 12%~16%.

3. A water-based high-gloss and abrasion-resistant gravure ink according to claim 1 or 2, characterized in that: The acrylic resin used was J-678 acrylic resin produced by BASF Shanghai, the soft film-forming acrylic emulsion used was RT-5300 produced by Beijing Lijiaqiao Chuangzhan Chemical Co., Ltd., and the ethylene-glycidyl methacrylate copolymer used was Igetabond™ (IB) produced by Sumitomo Chemical.

4. A water-based high-gloss and abrasion-resistant gravure ink according to claim 1 or 2, characterized in that: The pigment is selected from Lithol scarlet 335, golden red 258, titanium dioxide, phthalocyanine green or phthalocyanine blue for ink.

5. A water-based high-gloss and abrasion-resistant gravure ink according to claim 1 or 2, characterized in that: The ink also includes 3% to 10% of a pH stabilizer, 0.2% to 0.6% of a dispersant, 0.3% to 0.6% of a defoamer and 0.3% to 0.6% of a leveling agent.

6. The water-based high-gloss and abrasion-resistant gravure ink according to claim 4, characterized in that: Amines or amine compounds are used as pH stabilizers, titanate dispersants are used as dispersants, silicone defoamers are used as defoamers, and silicone leveling agents are used as leveling agents.

7. A water-based high-gloss and abrasion-resistant gravure ink according to claim 1 or 2, characterized in that: The dosage of the organosilicon coupling agent in the functionalized boron nitride nanosheets is 0.5% to 2% of the weight of the boron nitride nanosheets; the organosilicon coupling agent is selected from one of 3-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, glycerylpropyltrimethoxysilane and 3-mercaptopropyltrimethoxysilane.

8. The water-based high-gloss and abrasion-resistant gravure ink according to claim 6, characterized in that: The preparation method of functionalized boron nitride nanosheets is as follows: 1) Weigh an appropriate amount of boron nitride nanosheets and add them to an appropriate amount of anhydrous ethanol or isopropanol; use an ultrasonic processor to perform ultrasonic treatment for 30 to 60 minutes until a uniform and stable BN nanosheet dispersion is obtained; 2) In another container, dissolve 0.5% to 2% of 3-aminopropyltriethoxysilane in anhydrous ethanol and stir evenly; 3) Slowly add the 3-aminopropyltriethoxysilane solution to the boron nitride nanosheet dispersion to keep the system uniformly mixed; under the protection of inert gas, place the mixed solution in a reactor with a reflux device, heat to about 80°C to 90°C, and react for 3-4 hours; after the reaction is completed, cool the reaction system to room temperature; 4) separating the functionalized boron nitride nanosheets by centrifugation or filtration, and washing them with anhydrous ethanol or deionized water for multiple times to remove unreacted 3-aminopropyltriethoxysilane and by-products; finally, drying the washed boron nitride nanosheets at 60° C. to 80° C. to obtain boron nitride nanosheets functionalized with 3-aminopropyltriethoxysilane.

9. A method for preparing the ink according to claim 1, characterized in that: The method comprises the following steps: (a) Amination procedure: In a reaction kettle equipped with a stirring device, after mixing part of the deionized water and the pH stabilizer, slowly add the acrylic resin while stirring, and fully dissolve it at 70°C to 90°C to form an aminated modified acrylic resin liquid; (b) Dispersion pretreatment: The aminated resin liquid, ethanol, part of the defoaming agent, ethylene-methyl methacrylate copolymer, functionalized boron nitride nanosheets, dispersant and pigment are added to a dispersion device according to a formula ratio, and after being fully stirred, transferred to a sand mill for sand grinding treatment until the ink fineness reaches ≤20μm; (c) Mixing and dispersion procedure: The color paste after sand grinding is transferred to a slurry mixing barrel, and at the same time, a soft film-forming acrylic emulsion, a water-based emulsified wax, a leveling agent, the remaining defoaming agent and deionized water are gradually added at a certain stirring speed. After stirring evenly at a low speed, sampling is performed to test whether it meets the technical indicators, and then filtering and packaging are performed to obtain the ink.

10. The method according to claim 9, characterized in that The sand grinding step is repeated 2 to 3 times to ensure that the ink fineness is stably controlled at 20 μm or less.

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