Screen printing 1000 questions (297-316)

297. What is the decal method for transferring decals?
A: The decal method for transfer decals is to transfer the decals directly to the ceramic. In order to make the pattern on the flower paper and the product adhere firmly, a layer of adhesive must be printed on the pattern layer. For decals, the floral paper is first dipped in water to soften the starch (or dextrin) and gum arabic of the adhesive layer, and at the same time, the water-soluble glue of the pattern carrier becomes soft; at this time, the adhesive side of the pattern is transferred to The surface to be decorated, and the bottom paper can be easily peeled off.

298. What is the decal method for decals?
A: The decals are composed of paper, intermediate layer, decorative layer, and cover film (carrying flowers). Before decaling, it should be immersed in water. At this time, the middle layer will absorb water and be sticky. When the decals are attached to the ceramic products, the cover film as a carrier of the pattern does not need to be peeled off, and it can be volatilized together with other additives during the firing process without affecting the decal quality.

299. What are the components of the flower transfer film (middle layer)?
A: The film-forming liquid of the transfer film consists of acrylic resin, solvent and diluent.

300. What features do you need to remove the film?
Answer: The ideal removal film should have the following characteristics:
(1) Do not curl when immersed;
(2) When the squeegee passes, the flower film will neither tear nor scratch;
(3) When transferring, it can ensure that the graphic is not deformed;
(4) can be used for various shapes of products;
(5) It has good flexibility and can decorate uneven ceramic products on the surface.

301. Ceramic glaze paper decals screen printing ink composed of which materials?
A: The ceramic glaze decal paper screen printing ink is also called screen printing porcelain ink. It is composed of color materials, linking materials and ink additives.

302. What are the conditions for screen printing porcelain ink?
Answer: The link material of screen printing porcelain ink should meet the following requirements:
(1) Good adsorption of pigments;
(2) After the ink is mixed with the pigment, it has the fluidity required for printing;
(3) No web sticking during printing;
(4) The viscosity of the ink remains unchanged during the printing process;
(5) Good printability;
(6) When the flower paper is curled, there will be no cracks or peeling of the ink layer;
(7) After firing, the color depth is appropriate and stable.

303. What are the main components of screen printing porcelain inks?
A: The resins in screen printing porcelain inks are mainly polymethyl acetate and alkylated turpentine.

304. What ink additives are mainly used for screen printing porcelain ink?
A: The commonly used additives for screen printing porcelain ink include paraffin wax, dry oil, leveling agent, and lubricant.

305. Screen printing porcelain ink overprint sequence how to arrange?
A: When overprinting, consider the chemical reactions that will occur when the various colors of the porcelain ink will be burned during the process of baking, and consider the color temperature of each color ink. When the color is stacked, the porcelain ink with the lower burning temperature is printed below, and the high temperature porcelain ink is superimposed on it. Because during the baking process, the porcelain ink with low temperature still has unmelted particles after firing, because the high-temperature porcelain ink on it has not yet been solidified, allowing the gases produced by the melting of the porcelain ink below to pass through to avoid bursting of flowers.

306. What is the relationship between the color temperature of screen printing porcelain ink and the flux?
A: The color temperature of the porcelain ink is related to the flux of the pigment. In general, the light-colored porcelain ink contains more fluxes, and the color temperature of the color firing is lower; the porcelain ink with darker color contains less flux, and the color burns. The color temperature is high. In addition, the pH of the different fluxes is also different and has a greater influence on the color rendering of color. For example, gold red material with gold as the coloring agent, if using alkaline flux, Caisha is The color effect is good, red and bright; if using acidic flux, color rendering effect is poor, purple and dark.

307. How about the structure of web-printed ceramic underglaze decal paper?
A: The printed paper on the screen printed ceramic underglaze decal consists of cotton paper and backing paper. The graphic carrier is a tissue paper, also called a leather paper, which is thin and soft, which will increase the difficulty of screen printing. The solution is to temporarily bind the tissue paper to the liner paper. After the graphic is printed, the tissue paper is printed. Peel off the liner. Liner is usually made of 180g/m2 wood pulp paper.

308. What are the main components of the special paste liquid for flower paper?
A: The special paste liquid is made up of a certain proportion of adhesive and filling liquid. Commonly used as adhesives are soap powder, palsy powder, lily powder, and horseshoe powder. Agar, cotton vegetable, sodium alginate, etc. are used as a filling solution.

309. Enamel enamel can be divided into several categories according to function?
A: Enamel can be divided into 4 categories according to function:
(1) Bottom glaze: it is used as a transition layer of surface glaze combined with metal;
(2) Face glaze: enamel coated on the enamel transition layer, which can give the product a smooth and beautiful surface and a series of excellent physical and chemical properties;
(3) color glaze: colored glaze as decorative enamel products, but also can be used as color enamel glaze and decorative flower glaze;
(4) Special glaze: enamel with special functions such as high temperature resistance, high pressure, light emission, absorption or emission of infrared rays, insulation, and the like.
310. What are the main components of enamel glaze?
A: The main components of enamel glazes are matrix, enamel network formers, fluxes, opacifiers, adhesives, oxidants, colorants, and adjuvants.

311. What is a enamel network forming agent?
Answer: The network forming agent is the main body of the enamel and is the basis for the formation of a complete enamel. Generally, SiO2, B2O3, and P2O5 are used as network forming agents for enamel.

312. What is the role of enamel flux?
A: The fluxing agent accelerates the high-temperature chemical reaction during the melting process of the enamel glaze, that is, accelerates the breaking speed of the chemical bond in the structure of the high-melting crystalline substance (such as SiO2, etc.) in the composition, and causes the eutectic glaze to have eutectic oxide or compound. At the same time is also responsible for adjusting the physical and chemical properties of enamel glaze, such as adjusting the glaze coefficient of expansion, chemical resistance and so on.

313. What is the role of opacifier in enamel glaze?
A: The opacifying agent is added to ensure that the enamel glaze has sufficient hiding power. This ensures that during firing, the glass phase in the glaze will precipitate various gases and crystals, causing a change in the refractive index of the glaze and improving the surface gloss.

314. What is the role of adhesive in enamel glaze?
A: The adhesive agent is a compound that ensures and promotes the firm bonding between the enamel glaze and the metal surface. Typical adhesives are arranged according to the size of their closeness:
CoO>NiO>MoO3>MnO2>Fe2O3>As2O3.

315. What is the role of oxidants in enamel glaze during the melting process?
A: The oxidizing agent can provide oxygen for the glaze during the melting process of the enamel, so as to prevent certain oxides from being reduced during the melting process, and is an auxiliary agent for improving the whiteness of the glaze.

316. What is the role of auxiliaries in enamel glaze during the melting process?
A: Auxiliary agents are some (small) compounds added during the smashing of enamel glaze pieces, which can promote the better performance of various components of the enamel and improve the burning performance of enamel powder or glaze, thereby further improving the enamel. The physical and chemical properties of the glaze. For example, BaO can improve the porcelain surface gloss and resistance of borosilicate enamel glaze; MgO can improve the whiteness of titanium white enamel glaze; CaO can improve the chemical stability of industrial enamel glaze.

Source "Printing Technology - Equipment and Special Printing"