Ink varnish for high-definition dot ink and preparation method of ink varnish

Abstract

The invention relates to the technical field of water-based ink, in particular to varnish suitable for high-definition dot ink printing. The varnish is prepared from the following components in parts by weight: 40-60 parts of low-acid-value modified acrylic resin liquid, 20-30 parts of acrylic acid modified rosin resin liquid, 0.5-2 parts of organic amine, 1-3 parts of a composite dispersing agent, 0.5-2 parts of a composite thixotropic agent, 2-5 parts of a wear-resistant agent, 2-5 parts of a flatting agent, 0.3-1 part of a defoaming agent and the balance of deionized water. According to the varnish disclosed by the invention, the combination of a resin system and related auxiliaries is regulated and controlled, so that high reproducibility and relatively good storage stability of fine dots are realized, and meanwhile, the varnish meets the requirements of a high-definition dot printing process and a post-flexographic printing process.

Description

Technical Field

[0001] This invention relates to the field of water-based ink technology, specifically to an ink oil suitable for high-definition halftone water-based ink printing and its preparation method. Background Technology

[0002] Printing and packaging play a crucial role in modern life, enhancing visual experience and bringing great convenience. With the continuous development of printing technology, high-definition printing, especially high-definition flexographic printing, demands increasingly higher precision in dot reproduction. Existing high-definition dot printing inks generally suffer from instability after mixing with toners, resulting in uneven redispersement and affecting print quality. Furthermore, they are prone to settling and severe coarsening after high-temperature storage (above 42℃). Some inks, when applied to high-definition dot printing, also exhibit poor leveling, blurred dot edges, and uneven ink transfer, failing to meet the requirements of high-definition printing for fine dot reproduction.

[0003] To address the aforementioned issues, the industry has attempted to improve related performance by optimizing the resin system or adding additives. Patent CN201811154825 discloses an ultra-high molecular weight acrylic emulsion and its preparation method, as well as a water-based ink for halftone printing. This method uses an ultra-high molecular weight acrylic emulsion synthesized with a special surfactant as the core ingredient to formulate the ink, solving problems such as plate clogging, dot blurring, gloss, and stability in high-dot printing. However, its emulsion synthesis process is difficult to control, resulting in high costs and energy consumption. Furthermore, the ultra-high molecular weight emulsion has a relatively slow film-forming speed, which may lead to delayed drying during high-speed printing, causing dot adhesion and smudging. Patent CN117107385A discloses an ink fortifier, its preparation method, and its application. It uses a specific ratio of hydroxyethyl cellulose and hydroxypropyl methyl cellulose to improve the product's stability during room temperature / high temperature storage, making it suitable for high-dot tempered glass ink systems. However, the cellulose system, a key material used in this invention, generally has low heat resistance and is not suitable for high-temperature baking (>150℃) scenarios, limiting its application in the post-printing process of flexographic printing. Therefore, developing a high-definition halftone ink that combines low dot gain, stable storage, and environmental friendliness, suitable for flexographic printing, has become an urgent need in the field of printing additives. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an ink oil for high-definition halftone inks and its preparation method. By adjusting the resin system and related additives, it achieves high reproducibility of fine halftone dots and good storage stability, while meeting the requirements of high-definition halftone printing processes and flexographic printing post-processing.

[0005] An ink oil suitable for high-definition halftone water-based ink printing, by weight, is composed of the following components: 40-60 parts of low acid value modified acrylic resin liquid, 20-30 parts of acrylic modified rosin resin liquid, 0.5-2 parts of organic amine, 1-3 parts of composite dispersant, 0.5-2 parts of composite thixotropic agent, 2-5 parts of abrasion resistant agent, 2-5 parts of leveling agent, 0.3-1 part of defoamer, and the balance being deionized water.

[0006] Furthermore, the solid content of the low acid value modified acrylic resin liquid is 30%, and the solid content of the acrylic modified rosin resin liquid is 30%.

[0007] Furthermore, the organic amine is one or more of diethanolamine, triethanolamine, and dimethylethanolamine.

[0008] Furthermore, the composite dispersant is a mixture of a polycarboxylate dispersant and an organosilane coupling agent;

[0009] Furthermore, based on the mass ratio, the ratio of polycarboxylate dispersant to organosilane coupling agent is 1.5~2.5:1.

[0010] Furthermore, the organosilane coupling agent is selected from γ-aminopropyltriethoxysilane or γ-methacryloyloxypropyltrimethoxysilane.

[0011] Furthermore, the composite thixotropic agent is a mixture of organic bentonite and hydrogenated castor oil; Furthermore, based on the mass ratio, the ratio of organic bentonite to hydrogenated castor oil is 1:2.

[0012] Furthermore, the wear-resistant agent is a polyethylene wax dispersion; The leveling agent is a polyether-modified silicone leveling agent; The defoamer is an organosilicon-polyether modified defoamer.

[0013] The above-mentioned method for preparing an ink oil suitable for high-definition halftone water-based ink printing includes the following steps: S1. Weigh out 40-60 parts of low acid value modified acrylic resin liquid, 20-30 parts of acrylic modified rosin resin liquid, 0.5-2 parts of organic amine, 1-3 parts of composite dispersant, 0.5-2 parts of composite thixotropic agent, 2-5 parts of abrasion resistant agent, 2-5 parts of leveling agent, 0.3-1 parts of defoamer, and the balance of deionized water, by weight, for later use.

[0014] S2. Divide the defoamer and deionized water into two equal parts. Mix one part of the defoamer and one part of the deionized water with the composite thixotropic agent and stir. Heat the system to 40~45℃ and add the low acid value modified acrylic resin liquid, acrylic modified rosin resin liquid, organic amine, composite dispersant, abrasion resistant agent, leveling agent, and the remaining defoamer and deionized water in sequence. Stir until all components are fully mixed to obtain the initial ink oil product. S3. After filtering the initial ink-mixing oil, the ink-mixing oil is obtained.

[0015] Furthermore, the preparation method of low acid value modified acrylic resin liquid or acrylic modified rosin resin liquid is as follows: dissolve solid resin in a mixed solvent, and stir for 3-4 hours at a reaction temperature of 70-80℃ to obtain a low acid value modified acrylic resin liquid or acrylic modified rosin resin liquid with a solid content of 30%. The solid resin is a low-acid-value modified acrylic resin or an acrylic-modified rosin resin. The mixed solvent is a mixture of water, ammonia, and ethanol.

[0016] Furthermore, when the solid resin is a low-acid-value modified acrylic resin, based on a total mass of 70 parts of mixed solvent, the mass fraction of ethanol is 2-10 parts, the mass fraction of ammonia is 3.5-4.5 parts, and the remainder is water; When the solid resin is acrylic-modified rosin resin, based on a total mass of 70 parts of mixed solvent, the mass of ethanol is 2-10 parts, the mass of ammonia is 8.5-10 parts, and the remainder is water.

[0017] Furthermore, the speed conditions for the first stirring treatment were 1200~1500 rpm and the time conditions were 1~1.5 h; the time conditions for the second stirring treatment were 1~1.5 h.

[0018] The beneficial effects of the present invention are as follows: (1) The present invention uses low acid value modified acrylic resin and acrylic modified rosin resin in synergy. The low acid value acrylic resin reduces hydrophilic sites and improves the film density of the ink film, so that the mixed water-based ink has better dot reproducibility. At the same time, its molecular chain polarity is moderate, which stabilizes the pigment particles through the steric hindrance effect, avoids particle agglomeration, and improves the storage stability and printability of the ink. The acrylic modified rosin resin improves the leveling and rheological properties of the ink, improves the adhesion, film formation and printability of the ink, making it suitable for high-definition dot printing. At the same time, it improves the overall temperature resistance of the ink, making it suitable for the paperboard line process after flexographic printing.

[0019] (2) This invention utilizes the synergistic effect of composite dispersants and composite thixotropic agents to significantly improve the dispersibility and storage stability of the pigment in the ink. After adding the pigment, it can be uniformly dispersed in the ink by regular stirring. The water-based ink mixed with the pigment has good storage stability, can be stored at room temperature for more than one month without sedimentation, and remains homogeneous after being stored at 50°C for 7 days. It can be reused by manual stirring. At the same time, the composite dispersant enhances the interfacial bonding force between the pigment and the ink, avoiding the problem of dot blockage caused by pigment agglomeration during the printing process.

[0020] (3) The preparation method of the present invention is simple, the steps are controllable, the product quality is stable, and it is suitable for large-scale industrial production. Detailed Implementation Plan The present invention will be further described below with reference to specific embodiments, but this is not intended to limit the scope of protection thereof.

[0021] The first thing this invention aims to protect is an ink oil for high-definition halftone inks, which, by weight, consists of the following components: 40-60 parts of low-acid-value modified acrylic resin liquid, 20-30 parts of acrylic-modified rosin resin liquid, 0.5-2 parts of organic amine, 1-3 parts of composite dispersant, 0.5-2 parts of composite thixotropic agent, 2-5 parts of abrasion resistant agent, 2-5 parts of leveling agent, 0.3-1 part of defoamer, and the balance being deionized water; and the solid content of the low-acid-value modified acrylic resin liquid is 30%, and the solid content of the acrylic-modified rosin resin liquid is 30%.

[0022] In this invention, the low-acid-value modified acrylic resin is a modified styrene-acrylate resin (containing hydroxyl groups), with a low acid value (≤20mgKOH / g), a number-average molecular weight of 5000~10000, and a glass transition temperature of 60~80℃. The low acid value and extremely low carboxyl content in the resin reduce hydrophilic sites. Furthermore, the hydrophobic groups such as ester and ether groups introduced after modification can block the water molecule penetration pathway, improving the film density of the ink film and thus inhibiting dot gain. Simultaneously, its molecular chain has moderate polarity, which can stabilize pigment particles through steric hindrance, preventing aggregation and improving the ink's storage stability and printability.

[0023] The acrylic-modified rosin resin has a number average molecular weight of 3000-8000 and a softening point of 100-120℃. Its medium molecular weight and high softening point provide good temperature resistance while ensuring certain film-forming properties, making the ink suitable for use in flexographic printing post-processing on paperboard lines. It also overcomes the shortcomings of pure acrylic emulsions or water-based resins in terms of cost and substrate compatibility.

[0024] The organic amine is one or more of diethanolamine, triethanolamine and dimethylethanolamine, used in combination to stabilize the pH of the system, adjust the viscosity, ensure the solubility of the resin and the stability of the system, and reduce dot gain, pinholes and craters.

[0025] The composite dispersant is composed of a polycarboxylate dispersant and an organosilane coupling agent in a mass ratio of (1.5~2.5):1. The polycarboxylate dispersant has a number average molecular weight of 5000~10000; the organosilane coupling agent is selected from γ-aminopropyltriethoxysilane or γ-methacryloyloxypropyltrimethoxysilane. The composite dispersant of this invention can more efficiently disperse toner particles, prevent particle agglomeration leading to dot clogging, and improve dot reproduction accuracy.

[0026] The composite thixotropic agent is a mixture of organic bentonite and hydrogenated castor oil in a mass ratio of 1:2. The composite thixotropic agent of the present invention can impart excellent thixotropic properties to the ink, forming a gel when standing to prevent ink sedimentation, rapidly thinning under printing shear force to ensure uniform ink transfer, and returning to a gel state after standing for a certain period of time after printing, thus giving it a certain degree of storage stability.

[0027] The wear-resistant agent is a polyethylene wax dispersion, which forms a low surface energy lubricating and protective layer after drying and film formation, improving the friction resistance of the ink layer. At the same time, the polyethylene wax dispersion can also maintain the integrity of the dot edges without affecting color development and printing accuracy.

[0028] The leveling agent is a polyether-modified silicone leveling agent, which can reduce the surface tension of the ink and regulate the system compatibility. The defoamer is an organosilicon-polyether modified defoamer, which can quickly eliminate bubbles generated during the printing process and avoid pinholes and shrinkage defects.

[0029] The second aspect of this invention is the method for preparing the ink oil for high-definition halftone ink, which includes the following steps: S1. Preparation of composite dispersant: A composite dispersant is obtained by uniformly mixing a polycarboxylate dispersant and an organosilane coupling agent. The mass ratio of polycarboxylate dispersant to organosilane coupling agent is 1.5~2.5:1. S2. Preparation of composite thixotropic agent: Organic bentonite and hydrogenated castor oil are mixed evenly to obtain a composite thixotropic agent. The mass ratio of organic bentonite to hydrogenated castor oil is 1:2. S3. Preparation of low-acid-value modified acrylic resin solution: Add the mixed solvent (water, ammonia, and ethanol) to the reactor in the appropriate proportions, heat to 70-80℃, start stirring in the reactor, slowly add the solid low-acid-value modified acrylic resin, and continue stirring for 3-4 hours until the low-acid-value modified acrylic resin is completely dissolved, obtaining a low-acid-value modified acrylic resin solution with a solid content of 30%. Cool the low-acid-value modified acrylic resin solution to below 45℃ and discharge it for later use. In the mixed solvent, based on a total mass of 70 parts, the mass fractions of ethanol are 2-10 parts, ammonia is 3.5-4.5 parts, and the remainder is water.

[0030] S4. Preparation of acrylic acid modified rosin resin solution: Same as step S3, add solid acrylic acid modified rosin resin to obtain an acrylic acid modified rosin resin solution with a solid content of 30%. Based on a total mixed solvent mass of 70 parts, the mass fractions of ethanol are 2-10 parts, ammonia (25%) are 8.5-10 parts, and the remainder is water.

[0031] S5. Weigh out 40-60 parts of low acid value modified acrylic resin liquid, 20-30 parts of acrylic modified rosin resin liquid, 0.5-2 parts of organic amine, 1-3 parts of composite dispersant, 0.5-2 parts of composite thixotropic agent, 2-5 parts of abrasion resistant agent, 2-5 parts of leveling agent, 0.3-1 parts of defoamer, and the balance of deionized water, by weight, for later use.

[0032] S6. Divide the defoamer and deionized water into two equal portions. Mix one portion of the defoamer and the other portion of the deionized water with the composite thixotropic agent and add them to the reactor. Stir at 1200-1500 rpm for 1-1.5 hours. Then, heat the system to 40-45°C and add the low-acid-value modified acrylic resin solution, acrylic modified rosin resin solution, organic amine, composite dispersant, abrasion resistant agent, leveling agent, and the remaining defoamer and deionized water in sequence. Stir for 1-1.5 hours until all components are fully mixed to obtain the initial ink oil product. To ensure uniform mixing, add adjacent materials at 5-10 minute intervals, adding them directly while maintaining stirring throughout the process.

[0033] S7. Post-processing: Cool the initial ink oil in the reactor to room temperature, filter it using a 150-200 mesh filter to remove impurities and incompletely dispersed particles, and obtain ink oil for high-definition halftone printing; after filtration, seal the package and store it in a cool and dry place.

[0034] In this invention, the preparation method is simple, the steps are controllable, the product quality is stable, and it is suitable for large-scale industrial production.

[0035] In this invention, in the following embodiments, the solid low-acid-value modified acrylic resin was purchased from Hanwha Group, model S~60L; the solid acrylic modified rosin resin was purchased from Jiangsu Sanmu Group, model SM-8050; diethanolamine was purchased from Shandong Anda Chemical; triethanolamine was purchased from Sirbon Petrochemical, model TEA-995; dimethylethanolamine was purchased from Sirbon Petrochemical, model DMEA-995; polycarboxylate dispersant was purchased from Zhejiang Xinqi, model XQ-601; organosilane coupling agent was purchased from Zixin Yue, model KBM-903; organobentonite was purchased from Haimingsi, model Bentone SD-1; hydrogenated castor oil was purchased from BASF, model Cremophor CO-40; polyethylene wax dispersion was purchased from Longhai Chemical, model 255; leveling agent was purchased from BYK Chemical, model BYK-346; and defoamer was purchased from BYK Chemical, model BYK-024.

[0036] <Example 1> A method for preparing an ink oil for high-definition halftone inks includes the following steps: S1. Preparation of composite dispersant: Mix 0.6 parts of polycarboxylate dispersant and 0.4 parts of organosilane coupling agent evenly to obtain composite dispersant; wherein, by mass ratio, polycarboxylate dispersant: organosilane coupling agent = 1.5:1.

[0037] S2. Preparation of composite thixotropic agent: 0.17 parts of organobentonite and 0.33 parts of hydrogenated castor oil are mixed evenly to obtain a composite thixotropic agent. The mass ratio of organobentonite to hydrogenated castor oil is 1:2.

[0038] S3. Preparation of low-acid-value modified acrylic resin solution: Add the mixed solvent (water, ammonia, and ethanol) to the reactor in the appropriate proportions, heat to 70-80℃, start stirring in the reactor, slowly add the solid low-acid-value modified acrylic resin, and continue stirring for 3-4 hours until the low-acid-value modified acrylic resin is completely dissolved, obtaining a low-acid-value modified acrylic resin solution with a solid content of 30%. Cool the low-acid-value modified acrylic resin solution to below 45℃ and discharge for later use. In the mixed solvent, the mass fraction of ethanol is 2-10 parts, the mass fraction of ammonia is 3.5-4.5 parts, and the remainder is water.

[0039] S4. Preparation of acrylic acid-modified rosin resin solution: Same as step S3, add solid acrylic acid-modified rosin resin to obtain an acrylic acid-modified rosin resin solution with a solid content of 30%. The mixed solvent contains 2-10 parts by mass of ethanol, 3.5-4.5 parts by mass of ammonia, and the remainder is water.

[0040] S5. Weigh out 60 parts of low acid value modified acrylic resin liquid, 20 parts of acrylic modified rosin resin liquid, 0.5 parts of organic amine, 1 part of composite dispersant, 0.5 parts of composite thixotropic agent, 2 parts of abrasion resistant agent, 2-5 parts of leveling agent, 0.3 parts of defoamer, and the balance of deionized water, by weight, for later use.

[0041] S6. Divide the defoamer and deionized water into two equal portions. Mix one portion of the defoamer and the other portion of the deionized water with the composite thixotropic agent and add them to the reactor. Stir at 1200-1500 rpm for 1-1.5 hours. Then, heat the system to 40-45°C and add the low-acid-value modified acrylic resin solution, acrylic modified rosin resin solution, organic amine, composite dispersant, abrasion resistant agent, leveling agent, and the remaining defoamer and deionized water in sequence. Stir for 1-1.5 hours until all components are fully mixed to obtain the initial ink oil product. To ensure uniform mixing, add adjacent materials at 5-10 minute intervals, adding them directly while maintaining stirring throughout the process.

[0042] S7. Post-processing: Cool the initial ink oil in the reactor to room temperature, filter it using a 150-200 mesh filter to remove impurities and incompletely dispersed particles, and obtain ink oil for high-definition halftone printing.

[0043] In this invention, the ink oils prepared in Examples 2-4 are identical to those in Example 1, except for the different amounts of each component. The component contents of the ink oils prepared in Examples 2-4 are shown in the table below.

[0044] Table 1

[0045] Performance testing: Permanent Yellow PY139 water-based ink pigment produced by Shanghai Teyan Chemical Pigment Co., Ltd. was selected. High-definition halftone printing was performed using a 7:3 mass ratio of ink oil prepared in Examples 1-4 to pigment pigment. A commercially available conventional ink oil was used as a control group. The test items and results are shown in Table 2. Table 2

[0046] As shown in Table 2, the high-definition halftone ink for water-based printing prepared in each embodiment of the present invention has good storage stability after being mixed with pigments. The halftone printing edges are clear and free of smudging. Furthermore, the printing ink has good wear resistance and temperature resistance, making it suitable for flexographic printing and its subsequent processes.

[0047] Where there is no conflict, the above embodiments and features described herein can be combined with each other.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An ink oil suitable for high-definition halftone water-based ink printing, characterized in that, By weight, it consists of the following components: 40-60 parts of low acid value modified acrylic resin liquid, 20-30 parts of acrylic modified rosin resin liquid, 0.5-2 parts of organic amine, 1-3 parts of composite dispersant, 0.5-2 parts of composite thixotropic agent, 2-5 parts of abrasion resistant agent, 2-5 parts of leveling agent, 0.3-1 part of defoamer, and the balance being deionized water.

2. The ink oil for high-definition halftone water-based printing according to claim 1, characterized in that, The solid content of the low acid value modified acrylic resin liquid is 30%, and the solid content of the acrylic modified rosin resin liquid is 30%.

3. The ink oil suitable for high-definition halftone water-based ink printing according to claim 1, characterized in that, The organic amine is one or more selected from diethanolamine, triethanolamine, and dimethylethanolamine; the wear-resistant agent is a polyethylene wax dispersion. The leveling agent is a polyether-modified silicone leveling agent; The defoamer is an organosilicon-polyether modified defoamer.

4. The ink oil suitable for high-definition halftone water-based ink printing according to claim 1, characterized in that, The composite dispersant is a mixture of polycarboxylate dispersant and organosilane coupling agent; Furthermore, based on the mass ratio, the ratio of polycarboxylate dispersant to organosilane coupling agent is 1.5~2.5:

1.

5. The ink oil suitable for high-definition halftone water-based ink printing according to claim 1, characterized in that, The organosilane coupling agent is selected from γ-aminopropyltriethoxysilane or γ-methacryloxypropyltrimethoxysilane.

6. The ink oil suitable for high-definition halftone water-based ink printing according to claim 1, characterized in that, The composite thixotropic agent is a mixture of organic bentonite and hydrogenated castor oil; Furthermore, based on the mass ratio, the ratio of organic bentonite to hydrogenated castor oil is 1:

2.

7. A method for preparing an ink oil suitable for high-definition halftone water-based ink printing as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Weigh out 40-60 parts of low acid value modified acrylic resin liquid, 20-30 parts of acrylic modified rosin resin liquid, 0.5-2 parts of organic amine, 1-3 parts of composite dispersant, 0.5-2 parts of composite thixotropic agent, 2-5 parts of abrasion resistant agent, 2-5 parts of leveling agent, 0.3-1 parts of defoamer, and the balance of deionized water, by weight, for later use; S2. Divide the defoamer and deionized water into two equal parts. Mix one part of the defoamer and one part of the deionized water with the composite thixotropic agent and stir. Heat the system to 40~45℃ and add the low acid value modified acrylic resin liquid, acrylic modified rosin resin liquid, organic amine, composite dispersant, abrasion resistant agent, leveling agent, and the remaining defoamer and deionized water in sequence. Stir until all components are fully mixed to obtain the initial ink oil product. S3. After filtering the initial ink-mixing oil, the ink-mixing oil is obtained.

8. The preparation method according to claim 7, characterized in that, The preparation method of low acid value modified acrylic resin liquid or acrylic modified rosin resin liquid is as follows: dissolve solid resin in a mixed solvent, stir for 3-4 hours at a reaction temperature of 70-80℃ to obtain a low acid value modified acrylic resin liquid or acrylic modified rosin resin liquid with a solid content of 30%. The solid resin is a low-acid-value modified acrylic resin or an acrylic-modified rosin resin. The mixed solvent is a mixture of water, ammonia, and ethanol.

9. The preparation method according to claim 8, characterized in that, When the solid resin is a low-acid-value modified acrylic resin, based on a total mass of 70 parts of mixed solvent, the mass of ethanol is 2-10 parts, the mass of ammonia is 3.5-4.5 parts, and the remainder is water; When the solid resin is acrylic-modified rosin resin, based on a total mass of 70 parts of mixed solvent, the mass of ethanol is 2-10 parts, the mass of ammonia is 8.5-10 parts, and the remainder is water.

10. The preparation method according to claim 8, characterized in that, The speed conditions for the first stirring treatment were 1200~1500 rpm and the time conditions were 1~1.5 h; the time conditions for the second stirring treatment were 1~1.5 h.

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