Water-based resin is commonly used in inks

First, water-based ink and modern printing As we all know, printing is one of the four major inventions in ancient China. Printing can not be separated from the ink, the early ink and ink are the same as water-based; but because the printing plate was mostly carved out of wood, wooden version of the water easily deformed, so people gradually eliminated the water-based ink. With the development of modern materials technology and the increasingly stringent standards for the emission of organic volatile substances by environmental protection regulations in various countries, the use of water-based inks in the world has become more and more popular. The current annual output of water-based ink in our country is about 100,000 tons, and this figure will also increase substantially in the future.

Second, the characteristics of water-based resin commonly used in ink analysis compared with the resin used in ordinary ink, the resin can be used to produce water-based ink is very rare, mainly two categories: one is water-reducible polymer, most of the high acid value Alkali-soluble resins, such as maleated rosin or polyacrylic resins, and water-dispersible emulsion polymers, primarily modified acrylic emulsions. In China, most of the water-based inks used are pine rosin, which accounts for about 70% of the total amount. Such resins have the advantages of low price, simple manufacturing process, and high ink gloss. The disadvantages are poor solubility of the resin, and ethanolamine must be used. The use of hardly volatile alkalis as neutralizers and the use of alcohols or ethers as co-solvents have made the inks poor in water resistance after printing and the printing process is not stable, making it impossible to print high-quality prints. In order to improve the quality of the Malay rosin ink, we usually add an acrylic emulsion to it, so that the water resistance of the produced ink will be improved, but the printability is not greatly changed, and the cost is greatly increased. The production of acrylic resin water-based inks generally does not use only a single type of resin, usually using water-reducible resin slurry, and then adding a variety of emulsion-type resins, such as film-forming emulsions, non-film-forming emulsions, covering emulsions, etc. To meet different printing needs. Therefore, the manufacture of a good acrylic ink requires the operator to have a high level of technology and rich practical experience. For most water-reducible resins, the relationship between resin viscosity and content and pH is nonlinear, as shown in Figures 1 and 2. In the printing process, the viscosity of the ink constantly changes with the volatilization of water and ammonia. If a sudden change occurs, printing is undoubtedly very unfavorable. Adding a co-solvent to the ink can solve this problem. However, most acrylic emulsions are susceptible to demulsification in cosolvents and the stability of the ink during storage cannot be guaranteed. The printing of many thin film materials, due to the limitations of the printing conditions, must add a lot of solvents to the ink to adjust the drying speed, so the current water-based inks cannot achieve a breakthrough in thin film printing.

Third, the application of new resins in water-based ink With the development of modern polymer theory, we understand more and more clearly the relationship between the structure and properties of polymer surfactants. Theoretically, almost all resins that can be used in traditional oil-based inks, such as polyesters, phenolics, urea-formaldehydes, alkyds, epoxies, polyamides, and polyurethanes, can be made into water-soluble resins by intermolecular graft copolymerization. Of course, to achieve this goal, on the one hand, superb synthesis technology is required. On the other hand, there is a clear understanding of the relationship between pigments and resins in inks and the relationship between resins and substrate materials. Fortunately, after more than 10 years of hard work, we have made breakthroughs in this field, and we have developed a modified polyester-based water-based resin that can be used to manufacture water-based gravure and flexographic inks and can be used for film printing. Modified water-based epoxy resin. For flexographic and gravure printing of paper products, water is a very good solvent—non-toxic, inexpensive, and stable during the printing process; however, as water penetrates quickly on the paper, the resin will follow the inside of the paper. The film-forming resin on the surface of the pigment is reduced, resulting in low gloss of the printed product, serious floating color, and poor ink adhesion. This problem is present in both the rosin and water-reduced acrylic resins. In order to solve the problem of severe penetration of water-reducible resin on paper, we developed a modified water-based polyester, which is different in structure from traditional resins, such as the traditional styrene-acrylic resin structure-A-B. A-B-, while the modified polyester structure is -A-A-B-B-C-C-, and its synthesis method is as follows: First, the hydrophilic weak A-type material is pre-polymerized into a low-molecular-weight resin and then passed through. The B-type resin is combined with a hydrophilic type C material prepolymer to form a new high acid resin (AV ≥ 160 mgKOH/g). Because the affinity of the carboxyl groups in different parts of the polymer chain is different from that of NH4 + , the ink printed on the surface of the paper will infiltrate and volatilize with ammonia (NH3), and the A-stage polymer in the resin will quickly lose its hydrophilicity. Prevents the penetration of the resin into the paper; at the same time, due to the formation of hydrophobic resin, it can accelerate the penetration of water in the ink and improve the dryness of the ink.

Therefore, a water-based ink manufactured using such a resin can have good drying performance even without a co-solvent, thereby greatly reducing the level of volatile organic compounds of the ink. The modified water-based polyester can be used not only as a water-reducible resin for dispersion but also as a high-gloss fast fixing resin oil instead of an acrylic emulsion. The use of such resins for the production of water-based inks is simple and easy to learn; the inks produced are brightly colored, the printing process is stable, does not thicken, does not paste, and the applicability is good. The printed products have clear dots, high gloss, and good water resistance. It is suitable for middle and high grade flexo and gravure printing. Especially for water-based gravure inks made from this resin, the quality of printed matter is close to that of solvent-based gravure inks. Even without any co-solvent, high-gloss copper plates are printed at high speed. Paper, printed products can also be quickly dried without stickiness. Another important feature of modified water-based polyesters is economy. As the production of high-grade ink does not require acrylic emulsion, the cost of the ink is greatly reduced, and the average cost per ton of ink can be reduced by 2000 to 3,000 yuan. The new water-based polyesters can be blended with Malay rosin and various acrylic emulsions. For example, the use of polyester-based aminated resin oils added to ordinary rosin inks not only improves the ink's water resistance, but also enhances the printability. The gloss of the product, but also improved printability, while the cost is not much improved. Printing of thin film materials such as polyester, polyethylene, polypropylene, etc., currently uses solvent inks. Although a few manufacturers have introduced water-based thin-film printing inks, the drying speed, ink adhesion, and composite properties of printing products cannot meet various requirements. At the same time, they are expensive and cannot be applied. In China, machines used for film printing, such as plastic gravure printing machines, are relatively popular and the used inks are cheap. However, aromatic hydrocarbons are often used as solvents. This causes environmental pollution, damage to workers' health, and toxic substances contained in printed materials as packaging materials. The secondary pollution of the packaging presents an urgent need to solve the problem.

The use of water-alcohol system can achieve the goal of environmental protection, but the current water-alcohol-based resin has slow solvent release due to hydrogen bonding between molecules, and the resin is difficult to dry out, making it difficult to achieve high-speed printing. To solve these problems, we have developed a new type of resin that can be dissolved in water, alcohols, and aliphatic hydrocarbons. This kind of resin can be made into modified epoxy resin, polyurethane or polyamide resin according to different uses. We believe: With the perfection of this resin system, in the near future, a brand new environment-friendly ink will replace the traditional plastic ink, which not only can completely remove the toxic solvents of benzene, but also will not have the price. obvious changes. In short, water-based inks will have extraordinary performance in different printing fields. Of course, the development and production of multifunctional water-based resins is the key to achieving this goal.

(Author: Beijing Xinrongan Electronics Co., Ltd.)

Reprinted from: China LED Advertising Lighting Network