Introduction of colorful screen printing ink performance characteristics

Metal screen printing ink

The requirements for screen printing inks for metal signage are strong adhesion, good abrasion resistance, clear graphics after printing, fast drying, and no net sealing. Metal label printing inks are generally made of synthetic resin such as alkyd, phenolic, etc. as the linking material, and some special additives such as pigments and additives are added. The printing performance of this ink is good, and it can be dried naturally after printing or baked at 120°C for 2 hours. The surface of the ink film is bright and three-dimensional, and it has excellent adhesion and wear resistance with the aluminum plate. The ink film of this kind of ink is tested with the JM-1 type film wear instrument. The rubber wheel with a load of 750g can be pressed for 500 times. Above, grinding with cloth wheels can reach more than 5000 times.

If the screen is printed with a color label, reference may be made to the color ink of the color printing ink and the appropriate amount of ink and drying agent should be added when the screen is placed. The amount of ink desiccant added is about 5% to 8% of the total amount of oil and ink. Adding less is not easy to dry, and adding more affects the adhesion of the ink.

Plastic and paper screen printing ink

Screen printing is a more traditional printing process. Although the proportion of screen printing in the entire printing market is very small, but since the 1980s, its development speed has been in front of printing methods such as flat, convex and concave. The annual growth rate of advanced countries in the world has reached 8% to 10%. There are also more than 260 screen printing equipment and equipment manufacturers in China. There are about 150,000 employees and about 50 kinds of screen printing products. The annual consumption of the country is about 50,000. Tons, in recent years, with the continuous improvement of people's living standards, everyone's requirements for packaging are no longer limited to the protection of goods and the convenience of transportation, and higher demands are placed on packaging, decoration and design.

The range of screen printing printing materials is very wide, and more materials are used in packaging, including plastics, paper, metal, glass, ceramics, and various kinds of composite packaging materials and other screen printing applications on plastic packaging. The following describes the application of two inks on printing and packaging materials:

First, the application of plastic packaging

Materials commonly used in plastic packaging are: polyethylene (mainly high pressure and low pressure polyethylene), polypropylene, polyvinyl chloride, polyvinylidene chloride, and polyester. Most of the screen printing inks used in plastic packaging belong to the volatile drying type, requiring good printability, fluidity, resistance to netting and adhesion.

Second, the application of paper packaging

As the screen printing pattern has a thick ink layer and a strong three-dimensional effect, the grade of the packaging can be greatly improved. General paper packaging commonly used materials are mainly used in high-grade paper and cardboard, such as glass cardboard, gold cardboard, silver cardboard and so on. It is characterized by small fiber pores and a close texture. This series of inks are required to have light resistance, heat resistance, solvent resistance and abrasion resistance in printing.

Glass screen printing ink

The surface decoration, scale, and text of glass products are mostly screen printed. The ink used for screen printing on the surface of glass products is called glass color glaze. Glass glaze decoration process is generally: glass glaze preparation → screen printing plate production → screen printing → baked (fired) → finished product inspection → packaging.

Glass glaze has three components, namely base glaze, colorant and printing oil. The mixing of these three components is a purely physical process and there must be no chemical reaction between the various components. The fine powder of the base glaze and the colorant can be used as a printing ink in the ordinary sense by adjusting and synthesizing a suitable paste with a liquid printing oil.

Base glazes of glass glazes are low melting point glasses of the lead-boron-silicon system; various types of metal oxides are used for colorants; printing oils can be used to paste color glaze powders for printing in the silk screen printing process. In addition, the color enamel can be temporarily adhered to the surface of the glass product by virtue of its viscosity, and during the baking (burning) process, the printing oil itself must be completely volatilized to burn the enamel, so that the color enamel fused to the surface of the glass product. The printing oil should also have a certain drying speed, a certain viscosity, and the film formed by printing should have a certain thickness and strength, and should have good wettability when mixed with the color glaze powder.

Glass-colored glazes, like ceramic glazes, must be roasted (fired) after being printed on the product to be firmly attached to the surface of the product. The roasted flower is the process of melting the colored glaze on the surface of the product, and the glass product should not be deformed during the baking process. Therefore, the melting temperature of the color glaze should be close to or lower than the softening temperature of the glass product, so that during the baking process, when the colored glaze reaches the melting state, the surface of the glass product also begins to soften, and at this time, a part of the melted color glaze can be diffused. Penetrate to the surface of the product to form a very thin intermediate layer, and the color glaze is firmly fused with the product. The temperature of baking is generally controlled at 580-600°C.

Since the products and the glaze are subjected to thermal expansion and contraction at the same time during the baking process, the coefficient of thermal expansion of the base glaze should be as close to the coefficient of thermal expansion of the product as possible to prevent additional stress on the glaze of the product.

Glass glazes should also have bright colors, good gloss, strong hiding power, and good chemical stability. In order to improve its physical and chemical properties, a small amount of titanium oxide, cadmium oxide, zirconium oxide, etc. may be added to the base glaze.

Glass color glaze in addition to the ordinary color glaze, there are transparent glaze, translucent glaze and acid, acid and alkali glaze.

High temperature resistance of glass screen printing ink

The vigorous development of screen printing has led to the rapid development of various new types of screen printing inks, such as scented inks, fluorescent inks, foaming inks, and quick-setting inks. These inks are generally dried at room temperature. Glass printing and ceramic printing are dried at high temperatures. Therefore, high temperature resistant inks are often used for glass and ceramic printing inks. According to different substrates and different printing processes, high temperature resistant inks require different heat resistance temperatures.

Inorganic glass screen printing with two kinds of ink, one kind is the inorganic pigment after grinding, to reach a certain degree of fineness, then add acrylate, screen printing on the glass surface, need to be heated at high temperature (above 600 °C) 1 ~ 2min, ink layer and The glass surface melts together and has excellent fastness. The heat-resistant temperature of this ink is above 600°C. However, because this screen printing process is costly and the process is more complicated, it is rarely used in the screen printing industry.

The other type is inorganic glass ink with polymer compound as binder. Both amino type and epoxy type are required to be baked. The ink widely used in the domestic market is baked at 1300~1400°C for 30 minutes after screen printing. Heat-resistant temperature is relatively low, but baking time is longer, the ink has good fastness and hardness, brightness is also very good, can withstand low concentrations of electrolytes and solvents such as ethanol, acetone, benzene, cyclohexanone, etc. .

The printing temperature of the ceramics can be divided into two types according to the firing method: one is to burn at a temperature of 700-800° C. at the beginning, and the other is to be glazed and then fired at a temperature of 1100-1300° C. The heat-resisting temperature of the ink used in this firing method is required to reach 1100-1300°C; the other is that firing is performed at a high temperature of 1100 to 1250°C, and then firing is performed at a temperature of 900-1000°C. The heat-resisting temperature required for this type of ink is lower than that of the former, reaching 900-1000°C.

The existing high-temperature resistant inks used in ceramics and glass have high temperature resistance at temperatures above 600°C and even above 1000°C. In some glass containers, the heat resistance temperature of ink is sometimes lower than that of ceramics, such as 180-200°C. This kind of ink is also called low-temperature glass ink. It uses organic paint and organic pigment or imitation golden material instead of inorganic pigment. Made of pure gold, used to decorate glass and baked at 200°C for 10 minutes. In the existing high-temperature inks, the heat-resistant temperature of 1800~2000°C is less, and if it is required to be baked at this temperature for a long time, less ink can meet this requirement. At present, there are almost no inks capable of baking at around 200°C without discoloration, mainly relying on imports. However, the number of foreign manufacturers is also relatively small, and the heat resistance of the ink produced is not very stable, such as the printing wheel labels, which need to be printed. When baking at a temperature of 200°C for 3 hours, discoloration often occurs, and the cost of the ink used in the application is relatively high. At present, some screen printing industry developed countries have ink developed, the finished product price is relatively high, so this ink has a high value of use, can replace the same imported ink, reducing the printing cost of product production.


Source: International Screen Printing