High-grade ceramic decal paper fine screen printing technology

In the field of ceramic decals production, screen printing has developed rapidly since the introduction of new technologies and processes for screen printing in the early 1980s. From the pursuit of the printing color layer thickness to the application of materials according to the requirements, to obtain a thick and thin printing effect; from simply using the solid color block to organize the pattern screen to the available halftone dot reproduction of the original color tone, tone; The development of glaze online printing decals to the promotion of high-temperature quick-fire glaze color mesh printing paper, and the replacement of the traditional gravure printing technology of underglaze flower paper from screen printing; from screen printing ceramic decal paper to screen printing glass, enamel, stainless steel Applique papers... These products are showing their strong vitality and broad prospects with the characteristics of bright colors, bright and eye-catching, rich layers, strong three-dimensionality, resistance to acid and alkali corrosion, and versatility. In order to further take advantage of screen printing, the screen printing technology will be further advanced to produce high-quality decals with better quality, finer colors and softer colors to meet the requirements of export foreign exchange and people’s increasing art. Appreciation level, it is necessary to develop and apply fine-hanging technology in decal paper screen printing.

1. The necessity of developing fine screen printing technology
Chinese porcelain is world famous. Porcelain was the first invention in China, but now it is behind some advanced countries for various reasons. Especially in the decorative aspect of daily-use porcelain, due to defects such as rough old flowers, non-bright colors, and inelastic patterns, some fine ceramics cannot be sold in the international market for a long time. In addition to the innovation in the design of drawings and the optimization and upgrading of basic materials and equipment, the production technology and process must be further improved. It is very necessary to use the fine screen printing technology with 47 lines/cm (120 lines/inch) or more (including 120 lines, the same below). The web printing paper produced by the 120-line hanging net technology can combine the advantages of plain printing and screen printing. In addition to the colorful, rich, bright and strong three-dimensional features of screen printing, this product can be compared with offset printing products in a delicate and soft color tone.

Now the foreign net printing papers are all made by the hanging net process, the cable is 110~165 lines; the screen printing plates are made of 350 mesh polyester fiber or stainless steel wire mesh, and the whole screen printing process is used to produce decals, completely breaking the shackles of traditional craftsmanship. , The product has entered the high-end decoration, and has broken through the 175 line network point mark, up to 22 sets of color. In the platemaking, foreign countries boldly use two different lines of wire to hung their nets on the same flower face. The printed picture levels are pulled open, the color reproduction is good, the three-dimensional effect is strong, and the artistic effects are vivid. From the above situation, we can see that there is a gap between us. Our current screen printing decals are limited to 100 lines of screen printing. We cannot realistically copy world-famous paintings, modern scenery, and character photography. There are very few lines on line 120 and line 133. Therefore, the development of fine line-hanging technology is China’s catch-up. The world advanced level needs.

In terms of ceramics, there are common porcelain, mid-range porcelain and high-grade porcelain. In recent years, due to the improvement of people’s living standards and the improvement of their cultural qualities, the demand for high-grade daily-use porcelain and high-grade art porcelain has also increased year by year. People do not seem to care much about its price, but instead pay attention to whether its quality, styling, and decorative images are novel, peculiar, delicate, and unique. As a fine furnishings for artistic appreciation and embellishment environment, without exquisite decoration will lose its function; high-grade meals, tea sets and other daily-use porcelain, without exquisite decoration will also be inferior. Different grades of product production process should be different. The coarse wire mesh screen printing process is suitable for ordinary porcelain and mid-range porcelain decoration, while the fine mesh screen printing technology is necessary for high-grade porcelain production.

2. The feasibility of using fine screen printing technology

The success of fine-printing screen printing and decal printing is closely related to factors such as the quality of the mesh, the quality of the template, and the ink. Compared with coarse screen printing and solid color printing, these factors have higher requirements.

Whether or not the template can be selected to the right sophisticated screen can affect the size and shape of the printable dots, as well as the quality of the tonality of the print. To obtain a good print effect, theoretically the current The following types of network selection principles are popular:

(1) When the screen hole width is greater than or equal to the screen wire diameter, the diameter of the minimum network point d can not be less than the sum of the screen hole width K and screen wire diameter S, that is: d ≥ K 10 S;

(2) When the width of the mesh is smaller than the diameter of the wire, the diameter of the minimum mesh should be equivalent to twice the mesh width of the mesh and the wire diameter, ie: d = 2 (K 10 S);

(3) The diameter of the smallest dot shall be equal to the sum of twice the screen wire diameter and one times the width of the screen mesh, head p:d=K+2S;

(4) The diameter of the minimum dot should be equal to three times the screen diameter, ie: d=3S.

Now take 10% of the outlets can be well restored to meet the replication requirements. The diameters of the dots of 120 lines, 133 lines, and 150 lines are about 74 μm, 68 μm, and 59 μm, respectively. From the first principle of selection, the polyester monofilaments and stainless steel meshes are 500 meshes, 420 meshes, and 380 meshes. In the 355-mesh and 330-mesh series, there are many types of screen mesh whose mesh width is greater than or equal to the mesh wire diameter, which meets this requirement and is available for selection. Few screens are in line with the latter principles of selection. If you consider the issues only when you focus on the last few principles, you may feel that it is difficult to fine-tune the screen printing with more than 120 lines because you cannot choose the right screen. It is even considered impossible to deter. However, there is a first principle of selection. When selecting the network, you can avoid weaknesses and try to use mesh materials whose screen hole width is greater than or equal to the screen wire diameter for fine dot printing to ensure the best copy effect of 10% dots and obtain the ideal high-grade prints. Sometimes it is also possible to use 15% or 20% of the outlets as the minimum copy outlet, so that the screens that meet the latter principles are all available. This expanded the scope of the selection network.

For the stencil plate, the performance of the sensitizer has also been significantly improved in recent years. Many sensitizers in the plant have the characteristics of large photographic latitude and high resolution, and can meet the requirements for 120-line dot-matrix plate-making. The printing quality guarantees. At the same time, the indirect method and the straight-line method make it easier to obtain fine stencils, which are also useful in high-line printing of ceramic decals.

Thixotropy varnish printing performance is good, can improve the phenomenon of ink diffusion on the substrate, make the dots clear, strong points, less variables, so the highlights and dark tone parts by the loss, maintain a fine level of good reproduction.

The ultra-fine grinding process can change the fineness of the ceramic pigments, improve the printability of the ink, and the vividness of the fine dots after roasting. In order to improve the ink absorption performance of the decal paper printing carrier, a transfer film printing process may be used. Patterns are printed directly on dextrins or other types of adhesive layers and an acrylic film is applied over the pattern. The improvement of ink-absorbing performance is beneficial to the firmness and clearness of fine dot inks, and avoids the possibility of producing fine dots and stencils without obtaining fine dots. The floral film also facilitates the decaling operation of large-scale flower decoration and high-grade furnishings such as porcelain, art porcelain, and other special-shaped porcelains. It prevents the paper from wrinkling and scraping when the decals do not match with the curved body. Burning defects after burning, to avoid quality accidents, to ensure the significance of high-grade flower paper decoration.

The colorful and decorative selenium red and cadmium yellow ceramic pigments are not suitable for fine dot printing due to poor color performance, coarse pigment particles, thin printing layer, and dullness in color. Before the pigments have been further improved, these two colors can be used to coat with coarse meshes, and other colors can be solved by a combination of thin meshes and screen printing. According to foreign experience, the copying of the same flower face with two different line numbers can still obtain the effects of rich gradation, good color reproduction, strong stereoscopic effect, and artistic fidelity.

In addition, China's plate making and printing technologies are increasingly improving. Machines and equipment are constantly being updated. Subtle levels of screen printing theory are constantly being researched; these are the favorable conditions for using fine-pitch screen printing technology.

In summary, it can be said that it is practically feasible to promote the use of fine-line printing with more than 120 lines in the field of screen printing decals. It is feasible to decorate high-grade ceramics, glass, and enamel with high-grade flower paper.