A water-based gravure varnish and preparation method thereof

Abstract

The present application provides a water-based gravure varnish and a preparation method thereof. By introducing silsesquioxane as an organosilicon of modified acrylate, the silsesquioxane has a low surface tension, can improve the wetting properties of acrylic resin and substrate, and promote uniform coating of the coating. The silsesquioxane can form a three-dimensional network structure in the coating, adjust the rheological properties of the coating, and serve as an important component to reduce the surface tension of the copolymer, thereby enhancing the water resistance of the coating after drying. By adopting an aliphatic polyurethane acrylic resin, the technical problems of hot stickiness and cold brittleness of the water-based gravure varnish can be effectively improved. On the one hand, the wear resistance of the varnish after film formation can also be improved. The synthesis process is simple, the route is short, convenient, easy to control, and has high repeatability.

Description

Technical Field

[0001] The invention relates to the technical field of varnishes, in particular to a water-based gravure varnish and a preparation method thereof. Background Art

[0002] Water-based gravure varnishes are widely used in the printing industry to enhance the gloss and protective properties of printed products. Varieties include water-based varnishes, oil-based varnishes, UV varnishes, and solvent-based varnishes. Water-based varnishes are currently the most widely used in China due to their excellent environmental performance. However, traditional water-based gravure varnishes have several issues, including being sticky when hot and brittle when cold, poor abrasion resistance, and poor water resistance. These issues limit the quality and lifespan of printed products, necessitating the urgent need for new inventions to address these issues. Summary of the Invention

[0003] In order to solve the technical problems of the prior art water-based varnishes that are often hot-sticky and cold-brittle and have poor wear resistance and waterproof performance, the present invention provides a water-based gravure varnish with good wear resistance, high color and improved hot-sticky and cold-brittle properties.

[0004] The second object of the present invention is to provide a simple method for preparing a water-based gravure varnish.

[0005] In order to achieve the above first purpose, the technical solution adopted by the present invention is:

[0006] A water-based gravure varnish comprises the following components, measured by weight: 50-70 parts of organosilicon-modified acrylate emulsion, 10-20 parts of aliphatic polyurethane acrylic resin, 3-5 parts of alcohol preparation, 25-30 parts of deionized water, 1-2 parts of wetting and leveling agent, 0.2-0.8 parts of defoaming agent, and 3-4.8 parts of polyethylene wax emulsion. The organosilicon is silsesquioxane. By introducing silsesquioxane as the organosilicon of the modified acrylate, the silsesquioxane has a low surface tension, can improve the wetting properties of the acrylic resin and the substrate, and promote uniform coating of the coating. The silsesquioxane can form a three-dimensional network structure in the coating, adjust the rheological properties of the coating, and as an important component, reduce the surface tension of the copolymer, thereby enhancing the water resistance of the dried coating film. By adopting the aliphatic polyurethane acrylic resin, more preferably, the aliphatic polyurethane acrylic resin with a functional group of 2, the technical problem of the water-based gravure varnish being hot-tacky and cold-brittle can be effectively improved, and the abrasion resistance of the varnish after film formation can also be improved.

[0007] Preferably, the preparation method of the silicone-modified acrylate emulsion comprises the following steps:

[0008] 1) Heat the container containing 15% n-butanol to 100°C, introduce nitrogen protection, and continuously add acrylic acid, methyl methacrylate, hydroxyethyl acrylate, reactive emulsifier and part of the initiator dropwise within 3-3.5 hours at a uniform speed;

[0009] 2) Add silsesquioxane, n-butanol and the remaining initiator mixed solution and keep warm for 1.5-2 hours;

[0010] 3) Cooling to 80°C, filtering out part of the solvent, adding a neutralizer, stirring and dispersing for 30-40 minutes, and adjusting the pH value to obtain an acrylic resin with a larger molecular weight and a higher distribution concentration, by first adding part of the initiator and mixing it into the monomer mixture, first mixing part of the initiator with the reactive emulsifier and the pre-emulsion, and finally controlling the addition time and temperature of the remaining initiator, and adopting a uniform drop-adding mode. The higher the molecular weight, the better the properties of the resin.

[0011] Preferably, the volume ratio of the silsesquioxane to the total amount of acrylic monomers is 1:3-5. Since the surface tension of the copolymer is very small, the contact angle of the coating film to water is significantly increased, the hydrophobicity is enhanced, and the emulsification of the emulsion becomes difficult. Therefore, the volume ratio of the silsesquioxane to the total amount of acrylic monomers is preferably 1:4.

[0012] Preferably, in step 1), the amount of the partial initiator added is 25-30% of the total amount of the initiator.

[0013] Preferably, in step 2), the dropwise addition of the mixed solution is completed within 1-1.5 hours, and the reaction temperature is 85-90°C.

[0014] Preferably, in step 1), the reactive emulsifier is allyloxy fatty alcohol oxyethylene ether ammonium sulfate, which has both oleophobic and lipophilic groups, thus giving this type of special molecule both hydrophilic and lipophilic properties, but not entirely hydrophilic or lipophilic. This amphiphilic structure not only improves dispersibility, but also enhances the wetting and leveling properties of the substrate, thereby avoiding the occurrence of coating leaks.

[0015] Preferably, in step 1), the initiator is hydrogen peroxide; the neutralizer is diethanolamine. Selecting hydrogen peroxide as the initiator, on the one hand, by precisely controlling the reaction temperature and the holding time, a free radical polymerization reaction between the compounds is achieved to generate an acrylic resin with a large molecular weight, thereby making the paint film have good chemical resistance. On the other hand, hydrogen peroxide is cheap and readily available, and after decomposition, only water and oxygen are generated, which can be easily removed from the product.

[0016] Preferably, in step 1), the mass ratio of acrylic acid, methyl methacrylate and hydroxyethyl acrylate is 2:1:3.

[0017] Preferably, the defoaming agent is TEGO Airex 901W defoaming agent; the leveling agent is BYK333, and the alcohol preparation is a mixed solution of ethanol and isopropanol in a volume ratio of 1:1.

[0018] In order to achieve the above second purpose, the technical solution adopted by the present invention is:

[0019] A method for preparing the water-based gravure varnish as described in any one of the above items comprises the following steps:

[0020] S1. Place the organosilicon-modified acrylate emulsion, aliphatic polyurethane acrylic resin, deionized water, and alcohol preparation in a container and stir at a stirring rate of 800-1000 rpm for 15-20 minutes until the mixture is uniformly mixed.

[0021] S2. Add the wetting and leveling agent, defoaming agent, polyethylene wax emulsion into the reaction vessel and stir at a stirring rate of 800-1000 r / min for 5-8 min until the mixture is uniform;

[0022] S3. After stirring, filter and obtain the product.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. The present application provides a water-based gravure varnish, which introduces silsesquioxane as the silicone of modified acrylate. Silsesquioxane has a low surface tension, can improve the wetting properties of acrylic resin and substrate, and promote uniform coating of the coating. Silsesquioxane can form a three-dimensional network structure in the coating, adjust the rheological properties of the coating, and serve as an important component to reduce the surface tension of the copolymer, thereby enhancing the water resistance of the coating after drying. By adopting aliphatic polyurethane acrylic resin, the technical problem of hot stickiness and cold brittleness of water-based gravure varnish can be effectively improved. On the one hand, it can also improve the wear resistance of the varnish after film formation.

[0025] 2. The present application provides a method for preparing a water-based gravure varnish, which has a simple synthesis process, a short route, is convenient, easy to control, and has high repeatability. The synthesis is carried out in water, which is environmentally friendly, safe, and has very little odor. It overcomes many defects of traditional acrylic products such as hot stickiness and cold brittleness. The resulting product has good dilution stability, storage stability, and mechanical stability, is low in cost, and is suitable for industrial production. The raw materials used in production are simple, easy to obtain, and inexpensive, and overcome the shortcomings of pure oil or water-based resin systems after curing into films, such as low gloss, poor hardness, and poor water resistance. At the same time, the production line efficiency is improved. The product uses monomers as the dispersion liquid for the bulk reaction, which solves the problem of increasing viscosity of the system as the reaction proceeds during the synthesis process. DETAILED DESCRIPTION

[0026] The specific technical solutions of the present invention are described below in conjunction with specific embodiments 1-3:

[0027] Preparation of silicone modified acrylate emulsion:

[0028] 1) Heat the container containing 15% n-butanol to 100°C, introduce nitrogen protection, and continuously add acrylic acid, methyl methacrylate, hydroxyethyl acrylate, allyloxy fatty alcohol oxyethylene ether ammonium sulfate and 26% of the total amount of hydrogen peroxide dropwise within 3-3.5 hours at a uniform speed;

[0029] 2) Add silsesquioxane, n-butanol and the remaining hydrogen peroxide mixed solution and keep warm for 1.5-2 hours;

[0030] 3) Cool to 80°C, filter out part of the solvent, add diethanolamine, stir and disperse for 30-40 minutes, adjust the pH value, and obtain the product.

[0031] Example 1:

[0032] A method for preparing a water-based gravure varnish comprises the following steps:

[0033] S1. Add the components in Table 1, silicone-modified acrylate emulsion, difunctional aliphatic polyurethane acrylate resin, deionized water, and a mixed liquid of ethanol and isopropanol into a container, and stir at a stirring rate of 800 r / min for 15 minutes until the mixture is uniform;

[0034] S2, adding the wetting and leveling agent, defoaming agent, polyethylene wax emulsion and the like into the reaction vessel, stirring at a stirring rate of 800 r / min for 5 min until the mixture is uniform;

[0035] S3. After stirring, filter with a 1000-mesh nylon mesh to obtain the water-based gravure varnish.

[0036] Example 2:

[0037] A method for preparing a water-based gravure varnish comprises the following steps:

[0038] S1. Add the components listed in Table 1, silicone-modified acrylate emulsion, difunctional aliphatic polyurethane acrylate resin, deionized water, and a mixture of ethanol and isopropanol into a container, and stir at a stirring rate of 1000 rpm for 20 minutes until the mixture is uniformly mixed.

[0039] S2, adding the wetting and leveling agent, defoaming agent, polyethylene wax emulsion and the like into the reaction vessel, stirring at a stirring rate of 1000 r / min for 8 min until the mixture is uniform;

[0040] S3. After stirring, filter with a 1000-mesh nylon mesh to obtain the water-based gravure varnish.

[0041] Example 3:

[0042] A method for preparing a water-based gravure varnish comprises the following steps:

[0043] S1. Add the components in Table 1, silicone-modified acrylate emulsion, difunctional aliphatic polyurethane acrylate resin, deionized water, and a mixed liquid of ethanol and isopropanol into a container, and stir at a stirring rate of 900 r / min for 18 minutes until the mixture is uniform;

[0044] S2, adding the wetting and leveling agent, defoaming agent, polyethylene wax emulsion and the like into the reaction vessel, stirring at a stirring rate of 900 r / min for 7 min until the mixture is uniform;

[0045] S3. After stirring, filter with a 1000-mesh nylon mesh to obtain the water-based gravure varnish.

[0046] Comparative Example 1:

[0047] The organosilicon-modified acrylate emulsion in step S1 was replaced with ordinary acrylate emulsion, and the remaining components and preparation method were the same as those in Example 1.

[0048] Table 1: Weight ratio of Examples 1-3 and Comparative Example

[0049] Components Example 1 Example 2 Example 3 Comparative Example Silicone modified acrylate emulsion 50 64 70 - Acrylate emulsion - - - 50 2-functional aliphatic polyurethane acrylic resin 18 20 10 Deionized water 28.8 25.4 29.5 28.8 1:1 ethanol and isopropanol 3.5 4.8 5 3.5 BYK333 leveling agent 1 1 2 1 TEGO Airex 901W defoamer 0.2 0.3 0.5 0.2 Polyethylene wax emulsion 4.8 3 4 4.8

[0050] The water-based gravure varnishes prepared in Examples 1-3 and the comparative example and commercially available water-based varnishes were applied to a substrate using an 80-120 line anilox roller coating (roller coating) at a curing speed of ≥80 m / min (infrared drying and curing, 60-70°C). Performance tests were then conducted. The test results are shown in Table 2 below.

[0051] Anti-wet sticking (anti-water sticking, anti-beer sticking): Cut the sample into 12cm*6cm small squares, use a dropper to drop 1-2ml of water or beer on the varnished surface of the sample, fold it in half, and place it on a corrugated cardboard box with the varnished side facing the varnished side. Press a 2kg weight on the test sample and leave it at room temperature for 24 hours. Observe the test results. If there is no sticking, it means the anti-wet sticking effect is good.

[0052] Table 2: Performance test results:

[0053]

[0054]

[0055] The test results in Table 2 show that compared with commercially available water-based varnishes, the present application has fewer VOCs and is more environmentally friendly. In addition, the use of silicone-modified acrylic resin can significantly improve the wear resistance of the ink, adjust the rheological properties of the coating, and serve as an important component to reduce the surface tension of the copolymer, thereby enhancing the water resistance of the coating after drying.

[0056] Therefore, the present application provides a water-based gravure varnish, which introduces silsesquioxane as an organosilicon of modified acrylate. Silsesquioxane has a low surface tension, can improve the wetting properties of acrylic resin and substrate, and promote uniform coating of the coating. Silsesquioxane can form a three-dimensional network structure in the coating, adjust the rheological properties of the coating, and as an important component, reduce the surface tension of the copolymer, thereby enhancing the water resistance of the dried coating film. By adopting an aliphatic polyurethane acrylic resin, the technical problem of hot stickiness and cold brittleness of water-based gravure varnish can be effectively improved. On the one hand, it can also improve the wear resistance of the varnish after film formation. The preparation method provided, The synthesis process is simple, the route is short, convenient, easy to control, and has high repeatability. The synthesis is carried out in water, which is environmentally friendly, safe, and has very little odor. It overcomes many defects of traditional acrylic products such as hot stickiness and cold brittleness. The obtained product has good dilution stability, storage stability, and mechanical stability, low cost, and is suitable for industrial production. The raw materials used in production are simple and easy to obtain, and low in price. It overcomes the shortcomings of pure oil or water-based resin systems after curing into films, such as low gloss, poor hardness, and poor water resistance. At the same time, the production line efficiency is improved. The product uses monomers as the dispersion liquid for the bulk reaction, which solves the problem of the system viscosity increasing continuously as the reaction proceeds during the synthesis process.

[0057] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A water-based gravure varnish, characterized by: The invention is composed of the following components in parts by weight: 50 to 70 parts of organosilicon-modified acrylate emulsion, 10 to 20 parts of aliphatic polyurethane acrylic resin, 3 to 5 parts of alcohol preparation, 25 to 30 parts of deionized water, 1 to 2 parts of wetting and leveling agent, 0.2 to 0.8 parts of defoaming agent and 3 to 4.8 parts of polyethylene wax emulsion; The organosilicon is silsesquioxane, and the volume ratio of the silsesquioxane to the total amount of acrylic acid, methyl methacrylate and hydroxyethyl acrylate is 1:3-5; The aliphatic polyurethane acrylic resin is a difunctional aliphatic polyurethane acrylic resin; The preparation method of the organosilicon-modified acrylate emulsion comprises the following steps: 1) Heat the container containing 15% n-butanol to 100°C, introduce nitrogen protection, and continuously add acrylic acid, methyl methacrylate, hydroxyethyl acrylate, reactive emulsifier and part of the initiator dropwise within 3-3.5 hours at a uniform speed; 2) Add silsesquioxane, n-butanol and the remaining initiator mixed solution and keep warm for 1.5-2 hours; 3) Cool down to 80℃, filter out part of the solvent, add neutralizer, stir and disperse for 30-40 minutes, adjust the pH value, and obtain the product.

2. The water-based gravure varnish according to claim 1, characterized in that: In step 1), the amount of the partial initiator added is 25-30% of the total amount of the initiator.

3. The water-based gravure varnish according to claim 1, characterized in that: In step 2), the dropwise addition of the mixed solution is completed within 1-1.5 hours, and the reaction temperature is 85-90°C.

4. The water-based gravure varnish according to claim 1, characterized in that: In step 1), the reactive emulsifier is allyloxy fatty alcohol oxyethylene ether ammonium sulfate.

5. The water-based gravure varnish according to claim 1, characterized in that: The initiator is hydrogen peroxide; and the neutralizer is diethanolamine.

6. The water-based gravure varnish according to claim 5, characterized in that: In step 1), the mass ratio of acrylic acid, methyl methacrylate and hydroxyethyl acrylate is 2:1:

3.

7. The water-based gravure varnish according to claim 1, wherein: The defoaming agent is TEGO AIREX902W water-based defoaming agent; the wetting and leveling agent is BYK333.

8. The method for preparing a water-based gravure varnish according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Place the organosilicon-modified acrylate emulsion, aliphatic polyurethane acrylic resin, deionized water, and alcohol preparation in a container and stir at a stirring rate of 800-1000 rpm for 15-20 minutes until the mixture is uniformly mixed. S2. Add the wetting and leveling agent, defoaming agent, and polyethylene wax emulsion into the reaction vessel, and stir at a stirring rate of 800-1000 r / min for 5-8 min until the mixture is uniformly mixed; S3. After stirring, filter and obtain the product.

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