Overview Development of UV Printing for Screen Printing (I)

Compared with offset printing, lead printing and other printing processes, screen printing belongs to a small industry, but screen printing is developing faster than other printing processes, and it will develop in the direction of cutting-edge, mechanization and specialization. As an ink manufacturer, it is also a part of the paint, paint and varnish production industries. There are many manufacturing processes. The raw materials produced under certain conditions can be used for the production of screen printing inks, and they may be high quality inks.

The raw materials for the production of screen inks are basically the raw materials and resins needed for the production of other printing inks, house paintings, and the like. Mixing these raw materials and resins in a packaging can be used for screen printing. As a screen printer, its most prominent advantage is that it can push the squeegee to print on very long materials. When we analyze the printed materials and the chemical components contained in them, we find that the content of these chemical components far exceeds the amount used to produce the ink. As a manufacturer, we are faced with raw material problems and need to produce inks suitable for various materials. In fact, our production scale is small. Therefore, it is very difficult for us to produce various kinds of inks suitable for printing on various materials. Our increase in sales is also insufficient for researchers to research and develop in this area because we are still small producers.

UV inks are not new products. It has been a few years old. Can UV inks be used as a universal product in other printing? Most offset printing plants now print, dry, and stack prints at the same speed as substrates, just speed, and UV inks are not the best choice for offset printing. Most cylinder offset press designs are not equipped with UV curing reactors or With the UV lamp space, the offset printing factory would rather purchase the UV inks for the purchase of equipment because UV inks are expensive.

Right now, there are certain aspects of offset printing that use UV inks, such as metal surface decoration printing, and still use plastisol inks. However, they require very long conveyors for curing. Now, UV inks are used to make beer cans. From the perspective of screen printing and ink manufacturers, UV inks are well suited for screen printing.

Before talking about the characteristics and structure of UV inks, it is important to understand the physical or chemical changes that occur during the process of ink change from liquid to solid (curing process). The commonly used screen printing inks, its change can be divided into two basic types: solvent volatile type and chemical reaction type.

Solvent-evolving inks consist of three parts: resins, solvents, and additives. Most of the resins are ethylene, propylene and materials or paints. All solvent-evaporated coatings are classified as varnish. The powdered or solid resin is dissolved in a solvent and then added to the solvent. This solvent may be a mixture of two or three different components. Finally, additives may be added. The additives may be pigments, plasticizers or other additives. This type of ink is volatilized by a solvent and changes from a liquid state to a solid state. Once the solvent is completely evaporated, the ink becomes a dry film and the resin returns to the solid state.

Chemically reactive inks consist of four parts: resins, solvents, additives, and drying oils/catalysts. The resin is also dissolved in the solvent, the solvent is added to achieve the printing viscosity using the ink, and then the additive and the drying oil are added. The process of changing the ink from a solid to a liquid is an oxidation reaction, ie, a chemical reaction occurs between oxygen, a drying oil, and a resin to generate very active and unstable atomic groups, and these radicals rapidly react and polymerize, in other words, The radical reacts with oxygen molecules in the drying oil. After the polymerization reaction, the ink becomes a dry film and the solvent is volatilized and released. It only plays a role in increasing the viscosity in the printing, regardless of the curing and drying. There are also differences in this type of chemical reaction and catalysts can be added. Such as heat-curing enamel, rely on heat to promote the use of the right reaction, some need air drying, some need heat drying, some need heat and air or oxygen and catalyst, the ink becomes a dry film, the solvent volatilizes, it prints It only plays a role in increasing the viscosity, regardless of curing drying. There are also differences in this type of chemical reaction and catalysts can be added. For example, thermosetting enamels are heated to promote reactions, some require air drying, some require thermal drying, and some require heat to be combined with air or oxygen and a catalyst.