Application of Screen Printing Technology on Ceramic Seepage Tiles (in)

The effect of brick properties on printing quality

Different from the ordinary screen printing process, the properties of the brick (including the moisture content of the brick, temperature, etc.) have a large influence on the color and pattern quality of the product. In actual operation, the body must maintain a certain humidity And temperature can adapt to the requirements of the screen printing process.

1. Effect of Moisture Content of Brick on Printing Quality

The moisture content of bricks refers mainly to the moisture content of the bricks after they enter the screen printing process through the drying process. The degree of moisture content has a great influence on the screen printing process. When the moisture content of the brick is too low, the permeated glaze will be quickly absorbed by the brick when it passes through the mesh of the mesh, which can easily cause aggregation of the glaze particles, dry knots, and clogging of the mesh, causing difficulty in printing. When the moisture content of bricks is too high, the absorption rate of the enamel glaze by the bricks is slow. If the spacing between the bricks and the wire mesh is small at this time, the screen may not be able to leave before the enamel is attached to the mesh after scraping. The surface of the brick, ie, the glaze, easily adheres to the screen, causing the mesh to clog. Therefore, in the actual production, it is generally required that the moisture content of the brick be controlled below 0.2%.

2. The effect of brick temperature on printing quality

If the temperature of the brick is too high (greater than 70'C), the water in the glaze will quickly evaporate after encountering the high temperature body during the printing process, which will increase the viscosity of the glaze and make the viscous glaze easier. Plugging the screen mesh hole causes printing difficulties. In addition, the colored ions entering the green body will also migrate as the moisture in the enamel glaze evaporates, and the colored ions are concentrated from the inner part of the green body to the surface of the green body, resulting in not deep flowering. The pattern is blurred. However, if the temperature of the brick is too low (below 30° C.), the pores in the blank will shrink, the resistance of the enamel penetrating into the green body will increase accordingly, and the coloring ions will be difficult to enter into the interior of the green body, resulting in seepage. The glaze spreads laterally across the surface of the green body, making the product pattern blurry and light in color. Therefore, in order to improve the quality of printed products, the temperature of bricks should be strictly controlled, and the general control is 45-65'C.

Effect of the performance of the enamel glaze on printing quality

The enamel is equivalent to the printing ink in the ordinary screen printing process. It is usually added with a solid coloring compound. A fluid-like substance with a certain viscosity and stable storage (without delamination, precipitation and deterioration) formulated with water and active additives. It is required that the penetrating glaze must have the following properties: First, it has a certain viscosity, and it has a higher resistance when the squeegee moves; second, it has sufficient fluidity and can smoothly pass through the mesh mesh (that is, Bingham's fluid); The third is to achieve a certain degree of granularity to prevent clogging the mesh.

1. Effect of Viscosity of Penetration Glaze on Printing Quality

In a series of performance indicators of the glaze, the viscosity is a very important parameter and has a great influence on the printing quality. If the viscosity is too large, first of all, it is unfavorable to the printing process, which tends to produce sticking nets, blocking nets, and destroying the surface of the green body; secondly, when the glaze viscosity of the green body surface is large, the diffusion resistance of the ions increases, and the glaze stays. On the surface of the green body, it is difficult to penetrate into the interior, and the image is blurred and superficial after sintering at high temperature. The reasons for the low viscosity may have two aspects: one is the excessive addition of penetration aid; the second is that the concentration of the enamel itself is too low. If the viscosity is too low due to too much penetration aid, the coloring ions will seep too deep under the help of the penetration aid, resulting in the decrease of the concentration of coloring ions in the body, and the color becomes light after sintering at high temperature. . blurry. If the concentration of the stencil itself is too low, the moisture in the slush increases (in fact, water is also a kind of penetration aid), and the concentration of the coloring ions also decreases, and the image after high-temperature sintering is also fuzzy and light.

2. The effect of glaze size on printing quality

The glaze particle size has a certain influence on the printing quality. The surface tension of the detailed rules increases, and the glaze layer is prone to dry cracking, and the glaze is reduced after sintering. Burnt and other phenomena. If the particle size of the glaze slurry is too thick, the melting temperature will increase, affecting the penetration of the coloring ions into the green body, affecting the coloring ability of the color glaze, and reducing the color concentration of the pattern; at the same time, the glaze slurry with a too coarse particle size may be easily screen printed. The phenomenon of stencil printing will also speed up the wear of screens and reduce the resistance to printing. In actual operation, the control of the size of the glaze slurry generally takes half the size of the mesh opening size of the mesh as the upper limit of its particle size. (to be continued)