Screen printing ink status quo and market development trend (2)

3. The huge market potential of screen printing water-based inks and electron beam radiation curing inks

Screen printing water-based ink, also known as screen printing water-based ink, English name is water base screen printing ink. As its name suggests, water-based inks are water-based ink systems. Compared with solvent-based inks, it is solvent-free, non-toxic, odorless, and non-polluting. It meets the requirements of environmental protection. At present, solvent-based printing inks contain 50% to 60% of volatile components. If the diluent required for formulating ink viscosity is also taken into account, the volatile components emitted by the ink will be released when the printed product is dried. The total content is 70% to 80%. The volatilization of these organic solvents will have an adverse effect on the environment, and it will also have a detrimental effect on human health. As early as 1982, Germany promulgated the "Chemical Products Act," which regulates the protection of the human body in the workshop, the protection of general health, and the protection of the environment. The annual amount of organic solvent-based coatings (including bright oils and inks) in Germany is 350,000 tons, which is a huge number. According to the government's regulations, the German Industry Federation proposed to reduce the total production of solvent-based paints by 20% to 25% within 5 years. This will reduce air pollution from 70,000 to 90,000 tons of solvents. The strict environmental protection law implemented by the European Economic Community in 1992 will become the benchmark for the environmental protection laws of all countries in the world. In 1996, Austria also formally issued an ordinance that strictly restricted the addition of certain solvents and certain solvent components of the ink to no more than 5%, such as aromatic hydrocarbons. For screen printing plants in Austria, solvent-based inks have become water-based or UV-curable inks. Under the pressure of environmental protection laws, European and American countries have forced research institutions and some screen printing ink manufacturers to research and develop inks with low solvent or low solvent content. There is no doubt that screen-printing water-based inks will be greatly developed and continuously promoted. At present, Sweden, Germany and the United States have used water-based inks to achieve better results. Screen printing plants that have begun to use water-based inks will undoubtedly have an absolute advantage in market competition.

(1) screen printing water-based ink

1 Screen printing water-based ink composition structure characteristics

The binder for water-based inks consists of an aqueous gum or semi-gel solvent and an emulsion. The acrylates and copolymers are dissolved in water in a precise ratio, and after adding other solvents, a stable binder is obtained. Adding such a binder to pigments and auxiliary materials can produce screen-printed water-based inks. The particles of the composition have such a characteristic that the moisture can be volatilized and released relatively quickly during the formation of the ink layer film, thus forming a dry ink film. The viscosity of the screen printing water-based ink at printing can be adjusted with water. The used screen can be washed with water, and the ink residue remaining on the screen can be removed with a detergent and recycled. However, the use of water-based inks requires that the screen printing plate must have water resistance, so it is necessary to use water-resistant photosensitive adhesive for plate making.

2 Drying performance of screen printing ink

As mentioned previously, the screen printing water based ink contains particles of the composition in the ink, and when the water is volatilized and released relatively quickly, the surface of the ink film can be rapidly dried. Therefore, at 20 °C ~ 22 °C standard room temperature and relative humidity of 55% ~ 60%, it is best to use hot air to promote the water to accelerate the volatilization, especially non-absorbent substrates. Soft or rigid polyvinyl chloride and foil coated with adhesive shall be continuous drying devices. The convective air temperature at the inlet shall be maintained at 70°C～80°C, so that the dry temperature of the printed materials input by the stack Close to 35°C to 40°C. For substrates of different materials, the drying temperature should be adjusted accordingly to obtain better ink adhesion than solvent inks. In addition, another measure to improve the drying performance of screen-printing water-based inks is to add a small amount of cross-linking agent to improve the anti-diluent, alkali-resistance, and acid-resistance properties of the aqueous system prior to printing.

3 Development and application of screen printing inks in the Mainland

My domestic development and application of screen-printed water-based ink has attracted the attention of the research department and screen printing equipment manufacturers. Now screen printing water-based ink has achieved better results in packaging printing. For example, Hubei Huanggang Area Printing Material Factory has successfully developed a volatile dry water-based ink. The product is produced by using a natural ore and water-soluble resin produced locally and refined through grinding, blending, disposing and other production processes. It is suitable for screen printing packaging paper boxes, cartons and paper drums and other paper packaging products. This type of water-based ink has the following characteristics compared with commonly used solvent inks: 1 The print has a bright color, a clear picture, and a strong three-dimensional effect. 2 strong ink hiding power, no traces of ink film, pinholes, spots. 3 ink adhesion is good, and water resistance, light resistance, friction resistance. 4 non-toxic, odorless, no pollution to the environment. The 5 screen version is easy to clean and fast in color change. It will not stick or block nets, and it can prolong the service life of the screen, at the same time, it also reduces labor intensity and saves working time. 6 The price is lower than solvent ink, which is equivalent to 85% of the price of common paint. In addition to the above-mentioned paper products screen printing water-based inks, there are screen printing plastic water-based inks developed by the first plastics factory in Changge County, Henan Province. This type of ink is mainly used for the trademark printing of polypropylene and polybutylene and other plastic products. The ink was detected by the quality supervision and inspection of chemical products, and the quality was in line with the requirements. The characteristics of the ink are: strong adhesion, good firmness, clear printing graphics, bright color, short drying time, non-toxic, odorless, and no pollution. The production of water-based inks for screen printing in the Mainland has just begun. The output is very small and the scope of application is not large. However, it is expected that relevant government departments will soon issue regulations on restrictions on the use of organic solvents. Under the strict environmental protection pressure and the need for screen printing products to enter the international market, the screen printing industry will change the ink system and actively develop and produce "green" inks. Therefore, there is no doubt that the screen printing water-based inks have huge potential for market development.