2. Water-based ink pigments
The pigment gives the color characteristics of the ink and satisfies the printing requirements for color. General organic and inorganic pigments can be used for water-based inks. Since water-based ink resins are mostly alkali-soluble, pigments that use alkali are used when pigments are selected. However, the distribution density of pigments in ink is much greater than that of solvent-based inks, and the surface tension and polarity of water are all related to solvents. The large difference makes pigments difficult to disperse and affects the stability, viscosity, and pH of the ink. We added surfactants to increase the affinity of the resin and water and the affinity of the pigment and the water-soluble binder to solve the ink stability problem. . In addition, the viscosity and pH of the ink are precisely controlled. When the pH is higher than 9.5, the alkali is too strong, the viscosity of the ink will decrease, the drying speed will be slow, the water resistance will be poor, and the pH will be low. At 8 o'clock, when the alkali is too weak, the viscosity of the ink will increase, and the ink will be easily dried. This will cause defects such as dirty plate, stencil, and blistering. When we choose the pigments, we choose domestic pigments to have brilliant color and low viscosity. , system stable high-grade pigments to make water-based inks.
3. Water-based ink additives
In order to improve the performance of water-based inks, it is necessary to add various auxiliaries, and water-based ink auxiliaries are more important than solvent-based inks. Commonly-used water-based ink auxiliaries include the following.
1 Defoamer: used to eliminate the foam in water-based inks, the amount is generally 1% to 2%.
2 Ink stabilizer: It mainly prevents the ink from coalescence and mold during storage and transportation. It can reduce the viscosity of ink and adjust the pH value of ink. Generally, it uses ammonia or ethanolamine.
3 Others include dispersants, preservatives, leveling agents, slip agents, and cross-linking agents. These agents are used scientifically to improve the weakness of aqueous inks, thereby improving the stability of aqueous inks.
4. Water-based ink solvent
Water-based ink solvents need to have:
1 Dissolve the resin to give ink;
2 adjust the viscosity to give printability;
3 Adjust the drying speed. In particular, water-based inks are also required to have non-toxic properties, and thus its solvents are mainly pure water and a small amount of alcohols, such as water, ethanol, butanol, isopropanol, etc., which can assist water in enhancing the ability to dissolve the resin and improve the pigments. The dispersion performance, and accelerate the penetration, inhibit the foaming effect.
5. The preferred basic formula of water-based ink
Water-soluble acrylic resin 25%～35%
Water 15% to 25%
Ethanol 5%～15%
Triethylamine 5% to 10%
Pigments 10% to 30%
Additives 1% to 3%
6. Water-based ink production process
The first step is to grind and prepare the color paste: the water-soluble resin, pigment, auxiliary agent and solvent (water) are mixed, stirred and dispersed by a high-speed disperser, and ground into a backup color paste.
The second step is to formulate the ink: The standby colorant, auxiliary agent, and solvent (water) are mixed and stirred evenly. Through grinding and dispersing, they have sufficient fineness, luster and coloring power, and the filter package is an aqueous ink product.
In summary, we selected various types and varieties of water-soluble acrylic resins, selected pigments and auxiliaries through comparative tests, compounded with acrylic vinegar emulsions, added cross-linking agents, and optimized the formulation through orthogonal tests. The developed water-based ink products have been tested and used by relevant units to prove that all the indicators have reached the advanced level of similar products at home and abroad and have been well received by the users. Its main technical indicators are shown in Table 2.
Table 2 The main technical indicators of water-based ink
The pigment gives the color characteristics of the ink and satisfies the printing requirements for color. General organic and inorganic pigments can be used for water-based inks. Since water-based ink resins are mostly alkali-soluble, pigments that use alkali are used when pigments are selected. However, the distribution density of pigments in ink is much greater than that of solvent-based inks, and the surface tension and polarity of water are all related to solvents. The large difference makes pigments difficult to disperse and affects the stability, viscosity, and pH of the ink. We added surfactants to increase the affinity of the resin and water and the affinity of the pigment and the water-soluble binder to solve the ink stability problem. . In addition, the viscosity and pH of the ink are precisely controlled. When the pH is higher than 9.5, the alkali is too strong, the viscosity of the ink will decrease, the drying speed will be slow, the water resistance will be poor, and the pH will be low. At 8 o'clock, when the alkali is too weak, the viscosity of the ink will increase, and the ink will be easily dried. This will cause defects such as dirty plate, stencil, and blistering. When we choose the pigments, we choose domestic pigments to have brilliant color and low viscosity. , system stable high-grade pigments to make water-based inks.
3. Water-based ink additives
In order to improve the performance of water-based inks, it is necessary to add various auxiliaries, and water-based ink auxiliaries are more important than solvent-based inks. Commonly-used water-based ink auxiliaries include the following.
1 Defoamer: used to eliminate the foam in water-based inks, the amount is generally 1% to 2%.
2 Ink stabilizer: It mainly prevents the ink from coalescence and mold during storage and transportation. It can reduce the viscosity of ink and adjust the pH value of ink. Generally, it uses ammonia or ethanolamine.
3 Others include dispersants, preservatives, leveling agents, slip agents, and cross-linking agents. These agents are used scientifically to improve the weakness of aqueous inks, thereby improving the stability of aqueous inks.
4. Water-based ink solvent
Water-based ink solvents need to have:
1 Dissolve the resin to give ink;
2 adjust the viscosity to give printability;
3 Adjust the drying speed. In particular, water-based inks are also required to have non-toxic properties, and thus its solvents are mainly pure water and a small amount of alcohols, such as water, ethanol, butanol, isopropanol, etc., which can assist water in enhancing the ability to dissolve the resin and improve the pigments. The dispersion performance, and accelerate the penetration, inhibit the foaming effect.
5. The preferred basic formula of water-based ink
Water-soluble acrylic resin 25%～35%
Water 15% to 25%
Ethanol 5%～15%
Triethylamine 5% to 10%
Pigments 10% to 30%
Additives 1% to 3%
6. Water-based ink production process
The first step is to grind and prepare the color paste: the water-soluble resin, pigment, auxiliary agent and solvent (water) are mixed, stirred and dispersed by a high-speed disperser, and ground into a backup color paste.
The second step is to formulate the ink: The standby colorant, auxiliary agent, and solvent (water) are mixed and stirred evenly. Through grinding and dispersing, they have sufficient fineness, luster and coloring power, and the filter package is an aqueous ink product.
In summary, we selected various types and varieties of water-soluble acrylic resins, selected pigments and auxiliaries through comparative tests, compounded with acrylic vinegar emulsions, added cross-linking agents, and optimized the formulation through orthogonal tests. The developed water-based ink products have been tested and used by relevant units to prove that all the indicators have reached the advanced level of similar products at home and abroad and have been well received by the users. Its main technical indicators are shown in Table 2.
Table 2 The main technical indicators of water-based ink
Item Technical Indicators Measured Index Detection Standard Color Standard Near Standard Sample GB/T13217.1 Coloring Power (%) 90～110100GB/T13217.6 Viscosity (S) 50±3050GB/T13217.4 Luster (S) (60°C) >80GB/T13217.2 Fineness (μm)≤108 pH value 8.0～9.59 Priming (mm) 15～3019 Alkali-resistant, water-resistant 24h Good storage stability 5～30°C Good
Third, the application of environmentally friendly water-based ink and market outlook
The most important application field of environment-friendly water-based inks is packaged products, of which food packaging, tobacco and wine packaging, and children's toy packaging occupy a considerable proportion. With the improvement of people’s awareness of environmental protection, the urgent need for “green†printed materials is increasing.
According to statistics, there are more than 1,000 carton factories in each province in China. If we use 10% water-based ink to print high-grade cartons, each province will need more than 2,000 tons of water-based ink annually. This shows that the development of high-grade water-based ink will be There is a very broad market prospect.
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