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 a general sense by blending it with a liquid printing oil into a suitable paste.
Base glazes of glass glazes are low-melting glass of the lead-boron-silicon system; various types of metal oxides are used for the colorants; printing oils can be paste-processed in addition to the glaze powders during screen printing. It is also possible to temporarily adhere the color enamel 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 and burned, so that the color enamel will be fused on 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 580-600Â°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 Â°C) 1 ~ 2min, ink layer and The glass surface melts together and has excellent fastness. The heat-resistant temperature of this ink is above 600Â°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 1300~1400Â°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 700-800Â° C. at the beginning, and the other is to be glazed and then fired at a temperature of 1100-1300Â° C. The heat-resisting temperature of the ink used in this firing method is required to reach 1100-1300Â°C; the other is that firing is performed at a high temperature of 1100 to 1250Â°C, and then firing is performed at a temperature of 900-1000Â°C. The heat-resisting temperature required for this type of ink is lower than that of the former, reaching 900-1000Â°C. The existing high-temperature resistant inks used in ceramics and glass have high temperature resistance at temperatures above 600Â°C and even above 1000Â°C. In some glass containers, the heat resistance temperature of ink is sometimes lower than that of ceramics, such as 180-200Â°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 200Â°C for 10 minutes.
In the existing high-temperature inks, the heat-resistant temperature of 1800~2000Â°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 200Â°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 200Â°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.
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