Environment-friendly water-based gloss oil for package printing and preparation method of environment-friendly water-based gloss oil

Abstract

The invention discloses environment-friendly water-based gloss oil for packaging and printing and a preparation method of the environment-friendly water-based gloss oil, and relates to the technical field of packaging and printing. The coating comprises the following components: 30-50 parts of an acrylate copolymer emulsion, 10-20 parts of a waterborne polyurethane dispersion, 3-8 parts of modified nano cellulose, 2-7 parts of an inorganic nanoparticle compound, 3-8 parts of a coalescing agent, 2-5 parts of a leveling wetting agent, 0.5-2 parts of a defoaming agent, 2-6 parts of a cross-linking agent, 3-8 parts of a wax emulsion, 0.5-2 parts of a pH regulator and 15-35 parts of deionized water. The acrylate copolymer and the waterborne polyurethane are compounded, and the modified nano cellulose and the inorganic nano particle compound are combined, so that the glossiness, the wear resistance, the adhesive force and the water resistance are improved in a balanced manner, and the performance is close to or even superior to that of the traditional solvent type gloss oil; the evaporation resistance of water is remarkably reduced, the drying time is shortened to be within 20 seconds, the water-based ink is suitable for high-speed printing equipment, and the production efficiency is improved.

Description

Technical Field

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

[0002] With increasingly stringent environmental regulations and growing consumer awareness of environmental protection, the packaging and printing industry has an increasingly urgent need for environmentally friendly inks and varnishes. Traditional solvent-based varnishes contain large amounts of volatile organic compounds (VOCs), which release harmful gases during production and use, posing a threat to the environment and human health. Although some water-based varnish products have appeared on the market, their performance often falls short of that of solvent-based products.

[0003] The gloss of existing water-based varnishes is generally lower than that of solvent-based products, making it difficult to meet the visual requirements of high-end packaging. This is mainly due to the high surface tension of water during the film-forming process, resulting in poor film uniformity. Secondly, water-based varnishes have an unbalanced hardness and toughness, leading to poor abrasion and scratch resistance in the finished product, making it prone to scratches during transportation and use, affecting the appearance and protective performance of the packaging. Simultaneously, the high latent heat of vaporization of water results in slow drying speeds for water-based varnishes, impacting production efficiency, particularly limiting their application on high-speed printing presses. Furthermore, their adhesion to different printing substrates is unstable, easily leading to powdering and peeling. Some water-based varnishes are prone to whitening or performance degradation upon contact with water, limiting their application in humid environments.

[0004] The purpose of this invention is to provide an environmentally friendly water-based varnish for packaging printing and its preparation method, so as to solve the above-mentioned technical problems and provide a water-based varnish product that is both environmentally friendly and has excellent comprehensive performance.

[0005] The information disclosed above in this background section is only for enhancing the understanding of the background section of this invention, and therefore may include prior art that is not known to those skilled in the art. Summary of the Invention

[0006] The present invention aims to address the shortcomings of existing water-based varnishes in terms of gloss, abrasion resistance, drying speed, adhesion and water resistance, and to provide an environmentally friendly product with performance that is close to or even surpasses that of solvent-based varnishes.

[0007] To achieve the above objectives, the present invention provides the following technical solution: an environmentally friendly water-based varnish for packaging printing, comprising the following components: 30-50 parts of acrylate copolymer emulsion, 10-20 parts of water-based polyurethane dispersion, 3-8 parts of modified nanocellulose, 2-7 parts of inorganic nanoparticle composite, 3-8 parts of film-forming aid, 2-5 parts of leveling and wetting agent, 0.5-2 parts of defoamer, 2-6 parts of crosslinking agent, 3-8 parts of wax emulsion, 0.5-2 parts of pH adjuster, and 15-35 parts of deionized water.

[0008] Preferably, the acrylate copolymer emulsion is copolymerized from methyl methacrylate, butyl acrylate, hydroxyethyl acrylate and organosilicon monomers containing double bonds, with a glass transition temperature of 40-60°C, an average particle size of 80-150 nm, and a particle size distribution index (PDI) < 0.15.

[0009] Preferably, the modified nanocellulose is cellulose nanofibers with a diameter of 10-50 nm and a length of 200-800 nm, which have been modified on the surface by both silane coupling agent and cationic modifier.

[0010] Preferably, the inorganic nanoparticle composite is composed of nano-silica and nano-alumina in a 3:1 ratio, with carboxyl-containing polymer chains grafted onto its surface.

[0011] Preferably, the film-forming aid is a composite solvent composed of dipropylene glycol methyl ether and benzyl alcohol in a 2:1 ratio.

[0012] Preferably, the leveling and wetting agent is a compound of polyether-modified siloxane and fluorocarbon surfactant in a 3:1 ratio.

[0013] Preferably, the wax emulsion is a compound emulsion of polyethylene wax and polytetrafluoroethylene wax, with an average particle size of 1-3 μm.

[0014] This invention also provides a method for preparing the environmentally friendly water-based varnish as described above, comprising the following steps:

[0015] Step 1: Preparation of pre-dispersion: Add 60% of the total amount of deionized water to the reactor, slowly add modified nanocellulose, disperse for 30 minutes, add inorganic nanoparticle complex, continue to disperse for 20 minutes, add 50% of the total amount of film-forming aid, stir for 10 minutes to obtain pre-dispersion;

[0016] Step 2, mixing the main emulsion: Add the acrylate copolymer emulsion and the aqueous polyurethane dispersion to another container, stir at 300-500 rpm, slowly add the pre-dispersion, and continue stirring for 20 minutes to obtain the mixed emulsion;

[0017] Step 3, Addition of functional additives: Add leveling and wetting agent, defoamer, and wax emulsion to the mixed emulsion in sequence, stirring for 10 minutes after each additive is added; add crosslinking agent and stir for 15 minutes.

[0018] Step 4, Post-treatment: Adjust the pH of the system to 8.0-8.5 with a pH adjuster, add the remaining deionized water and film-forming aid, stir at 200-300 rpm for 30 minutes to make the system uniform, and filter through a 400-mesh sieve to obtain the final product.

[0019] Preferably, the dispersion temperature in step 1 is 38-42℃ and the dispersion speed is 800-1200rpm.

[0020] Preferably, the mixing temperature in step 2 is controlled below 45°C, and the material temperature in step 3 is controlled below 30°C.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. This invention achieves a balanced improvement in gloss, abrasion resistance, adhesion, and water resistance by compounding acrylate copolymers with waterborne polyurethane, combined with modified nanocellulose and inorganic nanoparticle composites. The performance is close to or even surpasses that of traditional solvent-based varnishes. By optimizing the film-forming aids and nanomaterial system, the evaporation resistance of water is significantly reduced, and the drying time is shortened to less than 20 seconds. It is suitable for use in high-speed printing equipment and improves production efficiency.

[0023] 2. This invention adopts a fully water-based system with VOCs content below 30g / L, which is far lower than that of solvent-based products. It meets the requirements of green printing and environmental protection regulations and is suitable for high-end fields such as food packaging. It can exhibit excellent adhesion and film-forming properties on a variety of substrates such as PET, paper, and aluminum foil. It has a wide range of applications and strong adaptability.

[0024] 3. The preparation process of this invention does not require high temperature and high pressure, and can be achieved using conventional dispersion and stirring equipment. The process is highly controllable and suitable for large-scale production. After pH adjustment and fine filtration, the system has good storage stability, is not prone to stratification or precipitation, and has a long shelf life. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0026] Figure 1 This is a schematic diagram of the preparation process of the present invention. Detailed Implementation

[0027] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] This invention provides an environmentally friendly water-based varnish for packaging printing, comprising the following components:

[0029] 30-50 parts of acrylate copolymer emulsion, composed of 20-30% methyl methacrylate, 10-20% butyl acrylate, 5-10% hydroxyethyl acrylate, and 2-5% organosilicon monomers containing double bonds, with a glass transition temperature of 40-60℃, an average particle size of 80-150nm, and a particle size distribution index (PDI) < 0.15;

[0030] 10-20 parts of waterborne polyurethane dispersion, with a solid content of 35-40%, prepared using aliphatic isocyanate to avoid yellowing, with a particle size of 100-200 nm;

[0031] 3-8 parts of modified nanocellulose, using cellulose nanofibers with a diameter of 10-50 nm and a length of 200-800 nm, the surface of which is modified by both silane coupling agent and cationic modifier, are uniformly dispersed in the aqueous phase without visible agglomeration.

[0032] 2-7 parts of inorganic nanoparticle composite, which is composed of 10-20nm nano silica and 20-30nm nano alumina in a 3:1 ratio, with carboxyl-containing polymer chains grafted onto the surface;

[0033] Film-forming aids, 3-8 parts, contain a composite solvent of dipropylene glycol methyl ether and benzyl alcohol in a ratio of 2:1, with the total content controlled below 8%, meeting environmental protection requirements;

[0034] 2-5 parts of leveling and wetting agent, which is a compound of polyether modified siloxane and fluorocarbon surfactant in a ratio of 3:1;

[0035] 0.5-2 parts of defoamer, which is a compound of mineral oil-based defoamer and organosilicon defoamer;

[0036] 2-6 parts of crosslinking agent, using water-based polyaziridine crosslinking agent, with a solid content of 40%;

[0037] 3-8 parts of wax emulsion, which is a compound emulsion of polyethylene wax and polytetrafluoroethylene wax, with an average particle size of 1-3 μm;

[0038] pH adjuster 0.5-2 parts, using ammonia or organic amine;

[0039] Use 15-35 parts of deionized water and adjust the solid content to 30-45%.

[0040] The present invention also provides a method for preparing the environmentally friendly water-based varnish for packaging printing as described above, comprising the following steps:

[0041] Step 1: Preparation of pre-dispersion liquid

[0042] Add 60% of the total amount of deionized water to the reactor, heat to 38-42℃, slowly add modified nanocellulose, and disperse at 800-1200 rpm for 30 minutes; add inorganic nanoparticle complex and continue to disperse for 20 minutes; add 50% of the total amount of film-forming aid, stir for 10 minutes, and obtain a pre-dispersion.

[0043] Step 2: Mixing the main emulsion

[0044] Add the acrylate copolymer emulsion and aqueous polyurethane dispersion to another container, stir at 300-500 rpm, slowly add the pre-dispersion, control the addition rate to keep the system temperature below 45°C, and continue stirring for 20 minutes after the addition is complete to obtain the mixed emulsion.

[0045] Step 3: Addition of functional additives

[0046] Cool the mixed emulsion to below 30°C, then add the leveling and wetting agent, defoamer, and wax emulsion in sequence, stirring for 10 minutes after each addition; then add the crosslinking agent and stir for 15 minutes.

[0047] Step 4: Post-processing

[0048] Adjust the pH of the system to 8.0-8.5 with a pH adjuster, add the remaining deionized water and film-forming aid, stir at 200-300 rpm for 30 minutes to make the system uniform, filter through a 400-mesh sieve to remove any possible agglomerates, test the solid content, viscosity and pH value, and adjust to the specified range.

[0049] Example 1

[0050] Prepare the following components: 40 parts of acrylate copolymer emulsion, 15 parts of waterborne polyurethane dispersion, 5 parts of modified nanocellulose, 4 parts of inorganic nanoparticle composite, 6 parts of film-forming aid, 3 parts of leveling and wetting agent, 1 part of defoamer, 4 parts of crosslinking agent, 5 parts of wax emulsion, 1 part of pH adjuster ammonia, and 21 parts of deionized water.

[0051] The preparation method is as follows:

[0052] Add 12 parts of deionized water to a dispersion vessel, heat to 40°C, slowly add modified nanocellulose, disperse at 1000 rpm for 30 minutes, add inorganic nanoparticle complex, continue dispersion for 20 minutes, add 3 parts of film-forming aid, stir for 10 minutes to obtain pre-dispersion.

[0053] Add the acrylate copolymer emulsion and aqueous polyurethane dispersion to a mixing tank, stir at 400 rpm, slowly add the pre-dispersion, control the temperature to not exceed 45°C, and stir for 20 minutes after the addition is complete to obtain the mixed emulsion.

[0054] Cool the mixed emulsion to 30°C, then add the leveling and wetting agent, defoamer, and wax emulsion in sequence, stirring for 10 minutes after each addition. Add the crosslinking agent and stir for 15 minutes.

[0055] Adjust the pH to 8.2 with ammonia, add the remaining 9 parts deionized water and 3 parts film-forming aid, stir at 250 rpm for 30 minutes to make the system homogeneous, pass through a 400-mesh sieve, and test the solid content, viscosity and pH value. Adjust to the specified range: solid content 38%, viscosity (Ford cup 4, measurement temperature 25℃) 45 seconds, pH 8.2.

[0056] Example 2

[0057] The following components were adjusted: 45 parts of acrylate copolymer emulsion, 12 parts of waterborne polyurethane dispersion, 6 parts of modified nanocellulose, 5 parts of inorganic nanoparticle composite, 7 parts of film-forming aid, and 4 parts of leveling and wetting agent; other components were the same as in Example 1.

[0058] The preparation method is the same as in Example 1, and the final product has a solid content of 40% and a viscosity of 50 seconds.

[0059] Example 3

[0060] Prepare the following components: 35 parts of acrylate copolymer emulsion, 18 parts of waterborne polyurethane dispersion, 4 parts of modified nanocellulose, 3 parts of inorganic nanoparticle composite, 5 parts of film-forming aid, 2.5 parts of leveling and wetting agent, 1.2 parts of defoamer, 3 parts of crosslinking agent, 4 parts of wax emulsion, 1.5 parts of pH adjuster ammonia, and 25 parts of deionized water.

[0061] The preparation method is the same as in Example 1.

[0062] Example 4

[0063] Prepare the following components: 48 parts of acrylate copolymer emulsion, 10 parts of waterborne polyurethane dispersion, 7 parts of modified nanocellulose, 6 parts of inorganic nanoparticle composite, 8 parts of film-forming aid, 4.5 parts of leveling and wetting agent, 0.8 parts of defoamer, 5 parts of crosslinking agent, 7 parts of wax emulsion, 0.8 parts of pH adjuster organic amine, and 18 parts of deionized water.

[0064] The preparation method is the same as in Example 1.

[0065] Comparative Example 1: Commercially available ordinary water-based varnish

[0066] 50 parts acrylic emulsion, 8 parts film-forming aid, 2 parts leveling agent, 1 part defoamer, and 39 parts water.

[0067] Comparative Example 2: Solvent-based varnish

[0068] 25 parts nitrocellulose, 15 parts acrylic resin, 35 parts ethyl acetate, 15 parts isopropanol, and 10 parts other solvents.

[0069] The products of Examples 1-4 and Comparative Examples 1-2 were coated onto PET films with a thickness of 0.05 mm. The wet film thickness was controlled using a wire bar coater, and the films were dried to constant weight in a 60°C oven with a dry film thickness of 1.5 ± 0.2 μm. The following performance tests were performed: 60° gloss was measured using a BYK Gardner micro-TRI-gloss gloss meter; abrasion resistance was tested using an abrasion tester according to GB / T 1768-2006, and the mass loss due to abrasion was recorded; the time it took for the film to completely dry and become non-sticky in a 60°C oven was recorded; adhesion was tested using the cross-cut adhesion test according to GB / T 9286-2021, with a rating from 0 to 5; the coating was immersed in deionized water for 24 hours, removed, wiped dry, and the gloss retention rate was measured; and the VOCs content was determined using gas chromatography according to GB / T 23985-2009.

[0070] The test results are shown in the table below:

[0071] Test Project Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 60° Gloss (GU) 93 94 91 95 78 95 Abrasion resistance (mg) 4.2 3.8 5.1 3.5 15.6 3.5 Drying time (s) 18 20 22 17 45 12 Adhesion Level 0 Level 0 Level 0 Level 0 Level 2 Level 0 Water resistance (%) 96% 97% 94% 98% 82% 98% VOCs content (g / L) 25 28 27 24 50 680

[0072] The test results above show that the gloss of Examples 1-4 is significantly higher than that of Comparative Example 1, and approaches or even reaches the level of the solvent-based varnish of Comparative Example 2. Example 4 has the highest gloss, indicating that the combination of high-content acrylic emulsion and an appropriate amount of leveling agent can further improve surface smoothness and light reflection ability, thereby improving the gloss of the product.

[0073] The abrasion resistance of Examples 1-4 is superior to that of Comparative Example 1, and the abrasion resistance of Examples 2 and 4 is close to that of solvent-based varnish. This indicates that the addition of the modified nanocellulose and inorganic nanoparticle composite of the present invention significantly improves the hardness and toughness of the coating film, forming a dense and abrasion-resistant structure, thereby improving the abrasion resistance of the product.

[0074] The drying times of Examples 1-4 were significantly shorter than those of ordinary water-based varnishes. This was mainly due to the optimization of the film-forming aids and the addition of nanomaterials, which reduced the resistance to water evaporation. Example 4, with its high solid content and low moisture content, dried the fastest.

[0075] The adhesion of Examples 1-4 was all grade 0, which was better than the grade 2 of Comparative Example 1. This indicates that the synergistic effect of acrylate and polyurethane, as well as the introduction of surface-modified nanomaterials, enhanced the interfacial bonding with the PET substrate.

[0076] The water resistance of Examples 1-4 is significantly better than that of Comparative Example 1, and the gloss retention rate of Example 4 is as high as 98%, which is close to that of solvent-based products. This indicates that the addition of the wax emulsion and crosslinking agent in this invention forms a hydrophobic network, thereby improving the water resistance.

[0077] The VOCs content of Examples 1-4 is significantly lower than that of solvent-based varnishes and lower than that of ordinary water-based varnishes, demonstrating good environmental performance.

[0078] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An environmentally friendly water-based gloss ink for packaging printing, characterized by comprising: It includes the following components: 30-50 parts of acrylate copolymer emulsion, 10-20 parts of waterborne polyurethane dispersion, 3-8 parts of modified nanocellulose, 2-7 parts of inorganic nanoparticle composite, 3-8 parts of film-forming aid, 2-5 parts of leveling and wetting agent, 0.5-2 parts of defoamer, 2-6 parts of crosslinking agent, 3-8 parts of wax emulsion, 0.5-2 parts of pH adjuster, and 15-35 parts of deionized water.

2. The environmentally friendly water-based gloss ink for packaging printing according to claim 1, characterized in that: The acrylate copolymer emulsion is copolymerized from methyl methacrylate, butyl acrylate, hydroxyethyl acrylate and organosilicon monomers containing double bonds, with a glass transition temperature of 40-60℃, an average particle size of 80-150nm, and a particle size distribution index (PDI) < 0.

15.

3. The environmentally friendly water-based gloss ink for packaging printing according to claim 1, characterized in that: The modified nanocellulose is cellulose nanofibers with a diameter of 10-50 nm and a length of 200-800 nm, which have been modified on the surface by both silane coupling agent and cationic modifier.

4. The environmentally friendly water-based varnish for packaging printing according to claim 1, characterized in that: The inorganic nanoparticle composite is composed of nano-silica and nano-alumina in a 3:1 ratio, with carboxyl-containing polymer chains grafted onto the surface.

5. The environmentally friendly water-based varnish for packaging printing according to claim 1, characterized in that: The film-forming aid is a composite solvent composed of dipropylene glycol methyl ether and benzyl alcohol in a 2:1 ratio.

6. The environmentally friendly water-based varnish for packaging printing according to claim 1, characterized in that: The leveling and wetting agent is a compound of polyether-modified siloxane and fluorocarbon surfactant in a 3:1 ratio.

7. The environmentally friendly water-based varnish for packaging printing according to claim 1, characterized in that: The wax emulsion is a compound emulsion of polyethylene wax and polytetrafluoroethylene wax, with an average particle size of 1-3 μm.

8. A method for preparing the environmentally friendly water-based varnish according to any one of claims 1-7, characterized in that: Includes the following steps: Step 1: Preparation of pre-dispersion: Add 60% of the total amount of deionized water to the reactor, slowly add modified nanocellulose, disperse for 30 minutes, add inorganic nanoparticle complex, continue to disperse for 20 minutes, add 50% of the total amount of film-forming aid, stir for 10 minutes to obtain pre-dispersion; Step 2, mixing the main emulsion: Add the acrylate copolymer emulsion and the aqueous polyurethane dispersion to another container, stir at 300-500 rpm, slowly add the pre-dispersion, and continue stirring for 20 minutes to obtain the mixed emulsion; Step 3, Addition of functional additives: Add leveling and wetting agent, defoamer, and wax emulsion to the mixed emulsion in sequence, stirring for 10 minutes after each additive is added; add crosslinking agent and stir for 15 minutes. Step 4, Post-treatment: Adjust the pH of the system to 8.0-8.5 with a pH adjuster, add the remaining deionized water and film-forming aid, stir at 200-300 rpm for 30 minutes to make the system uniform, and filter through a 400-mesh sieve to obtain the final product.

9. The preparation method according to claim 8, characterized in that: In step 1, the dispersion temperature is 38-42℃ and the dispersion speed is 800-1200rpm.

10. The preparation method according to claim 8, characterized in that: In step 2, the mixing temperature is controlled below 45°C, and in step 3, the material temperature is controlled below 30°C.

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