Ceramic printing (four)

Other ceramic printing processes

(1) Thermochromic Ceramics The so-called heat-sensitive ceramics are coated with a layer of thermochromic ink film on the surface of the ceramic body to cover the bottom of the color picture. When the heat reaches a certain temperature, the ink film becomes transparent. Make the bottom of the picture reveal the way to achieve the purpose of decoration. The thermal color-changing ceramic pattern is distinctive in daily life, with vivid colors, obvious changes, unique mystery and artistic features.

Due to the thermochromic ink itself, the ink film must have a certain thickness (usually 0.15-0.6mm) to achieve the decorative effect. An ink film of this thickness can be printed only by screen printing.

(2) Gold-clad ceramics with glaze Since precious metals are more valuable, when they are used to decorate porcelain plates, the printed (or delineated) decorative layers are relatively thin and generally do not exceed 0.1 μm. In addition, the decorative layer should be able to withstand long-term washing and knife and fork grinding, but also to withstand the hand-washing and stacking caused by the wear.

As far as the decorative layer itself is concerned, if the gold film is too thin, the requirement for the service life of the decorative device cannot be achieved at all. The use of a glaze protective layer can make up for the above deficiencies, but it requires secondary baking, which is too costly. This is why many dishes use a simple color picture without gold decoration. If gold is used to decorate, it is generally only to paint the border with gold with higher gold content.

Heraeus Company introduced a bright gold decorative layer cover glaze, used in the production of decals, to solve the above problems. In decals production processes, both gold and glaze protective layer pastes are used. Then, it is also baked in the temperature range of 800-840°C. Users can choose any transparent glaze or matt glaze as the protective glaze of the gold decorative layer. After baking, they can be bright golden or soft gold shiny after being polished. The company has produced a total of six products that are bright yellow, bright lemon yellow and bright platinum plastic and transparent glaze or matte glaze. Figure 4-11 is a sectional view of a glazed gold ceramic decal.
The production process of the decals: a. printing gold glue; b. stamping L406 film on the printed gold plastic pattern; c. printing ceramic paint (if necessary), but can not cover the gold plastic; d. Screen printing ink protection glaze or paste; e. Cover with protective glaze printed on the gold flower face; f. Stamping the whole flower paper L406 film.
Durability test: Gold decorative products covered with protective glaze are subjected to a certain standard test to meet the following process conditions:

a. glaze protective layer is flat and smooth, the thickness can not be less than 5-15μm; b. ceramic products in the baking temperature of 280-840 °C must have a holding time of 10-15min; c. After cooling the product is cooled, Avoid cracking on the cover glaze surface.

The cover glaze gold plastic ornaments (ceramics) can be tested for abrasion resistance, knife resistance and resistance to automatic dishwasher washing.

(3) Screen ceramic pastel printing decal decoration process Pastel pigment After screen printing, the image is reproduced on the paper bearing film, and then it is re-attached to the top of the ceramic armor. After roasting, it shows a bright color, which is called glaze powder. Color decal decoration craft. It is a ceramic decoration process with a long history and rich ethnic characteristics. Silk-screen printing and decal decoration have only recently emerged in ceramics. Prior to this, the ceramic pastel decoration was entirely drawn by hand. The procedure was: using a seasoning brush or an engraved rubber stamp to draw or print a tiger line corridor on the ceramic vessel, and then use a stylus to add various pastels. Pigments are drawn in dotted lines, and images can also be made by spraying pigments with paper patterns. The decorative pattern of pastel paint is thick, colorful, and has strong hiding power. It has a unique ethnic decoration network for the decoration of landscapes and mane images. However, this kind of decoration is entirely made by hand-painting, so the work efficiency is slow, it is difficult to make the fine craftsmanship, and the colorful network wire floral pattern can not be mass-produced, and it is also unable to decorate high-grade daily-use porcelain. After the silk screen printing process was introduced into the pastel ceramic applique decoration, it was handcrafted into full mechanized production, thereby saving a lot of labor, and due to the application of color separation and screen making, fine pattern designs can be made, and pastel applique paper can be used. Complete screen printing and color registration can also be accomplished by a combination of printing and manual methods. Some landscape mane freehand paintings are only hand-rendered to express their artistic style. The procedure is: First, a light outline tiger line is printed, which is attached to a ceramic vessel, and then the painting personnel dyes and embellishes it with a stylus pen.

(4) Application of UV ink in ceramic decoration Ultraviolet (UV) technology has many advantages. Theoretically, it is ideal for ceramic decoration. Its advantages are as follows:

1 There is very little solvent evaporation in the production process;
2 Fast drying, decorative products can be handled in a short time;
3 Small footprint and low energy consumption;
4 In the production process, the viscosity of the ink will not change;
In the automated production line, UV drying can increase the drying speed, which is a key factor, so it is particularly suitable for the production of ceramic decals. At present, UV inks used in ceramic decorative printing should have the following characteristics:
1 Drying time should be suitable for screen printing production line (about 20m/min);
2 Suitable for different pigments, can be bonded with high concentration pigments;
3 The binder should not be brittle after UV drying, and should be flexible (especially important for decals);
4 It can completely decompose and evaporate at about 400 °C;
The ink layer with a thickness of about 5100 μm can not leave any trace defects after grilling (without peeling, flecking, etc.);
6 suitable for fast burning;
7 non-toxic;
8 Viscosity is suitable for screen printing.

UV drying ceramic inks suitable for direct cable are currently technically advanced and can be used in large-scale production. Four sets of color overprinting roasted flower products, the thickness of each ink layer is 15μm, the speed of the production line can reach 10-20m/min, there will no longer be any problems. This makes it possible to decorate almost any decorative floral surface with prints of four colors (yellow, blue, magenta, black). In the case of a baking temperature of 900-960° C. and a fast grilling time of 20-30 min, no baking defects can occur. The space required for an on-line four-color printing press was reduced to about 8-10 m, and the entire print time was reduced to less than 1 min. The screen does not have to be cleaned after printing, because even after a 1h dwell time, a print image of the same quality can still be obtained. Although UV linking materials are more expensive than traditional linking materials, it is more advantageous for direct screen printing considering site, time, and energy savings.

After UV drying and baking, it will form a beautiful gold film that is comparable to the standard product quality. UV drying gel and electro-optic gold gel have been successfully applied in practical applications.

In addition, the advantages of the UV drying principle also apply to the production of ceramic decals. In recent years, breakthroughs have been made in the development of decals for UV drying screen printing materials. Small series of four-color ceramic decals that meet the conventional quality standards have been produced. However, it is still necessary to print a layer of traditional solvent-containing transparent cover film on the decal paper to keep the printed image clean. This UV-drying cover film does not have sufficient elasticity and tensile strength to meet the need for decals. The characteristic is that it breaks quickly during storage - presumably because the unreacted double bonds in the cover film are cross-linked together - and this has hindered its industrial application. Therefore, there is still a great deal of research work to do to produce products that can really be used in the ceramic industry.

UV drying is obviously limited by conditions such as printing, hardening, firing, and pigment layer thickness. The maximum thickness of the ink layer suitable for standard baking time and temperature is about 100 μm. Despite such limitations, the future of UV drying is still promising, especially in the development of four-color printing.




Source: PACK.CN