Tinplate printing principle:
Tinplate printing makes use of the physical properties of water, ink repel each other, by means of printing pressure, blanket graphic on the transfer to the Tin plates, belongs to the offset of the principle. Because Tin has special physico-chemical reprocessing properties of D, as well as print, printing processes and conventional offset printing vary greatly.
Tinplate printing inks has special requirements:
(1) requires that ink has good adhesion and mechanical properties
Due to the tin cans of food made of the final print, toys, metal, and chemical products, tanks, barrels, requires cutting, bending and stretching techniques, thus requiring printing inks to tinplate has good adhesion and mechanical properties. In order to increase ink adhesion, Tin needs to be white base first before printing. White is the color scheme of the image, have very high luminosity. After joining other high energy of hue, can improve the colors formed by brightness levels.
(2) requirements for white ink
Tinplate surface of white (or yellow), metallic, in advance of the printed color, need white or printed on white coated, ink coverage limits, single color presses often need 2 white, the brightness of up to 75%. Whitetinplate printing products as an important indicator of quality, requires white ink primer with good adhesion, after repeated high temperature baking-yellowing, high temperature steam do not lose colour. Primer of tinplate can increase adhesion of Tin, white ink good adhesion. Primer epoxy amine commonly used type, has a light color, after repeated baking-yellowing, no aging characteristics and good flexibility, impact resistance performance.
(3) requirements for color ink
Tinplate printing color ink, in addition to the outside should have some degree of water resistance, should also have their special requirements. Because of tinplate surface does not penetrate water and solvents needed dry after baking, so the ink for heat-curing type. High tinting strength and durability requirements of pigment. Printing inks in addition of offset printing ink of basic performance, according to the characteristics of the printing should have heat resistance, ink film adhesion resistance, good impact resistance, hardness, cooking and light resistance and so on.
(4) the ink drying process
In the production of Tin plate printing, ink drying is a complex chemical reaction process. To control the ink drying speeds, mastering the physico-chemical mechanism of drying, in order to effectively carry out quick print job, ensure product quality. Ink drying too fast would degrade the normal transfer of ink, affecting the normal production causing imprinted issued, light ink, printed version, the roller surface appears dry ink, ink under the pass is blocked; dry printing graphic expansion; the desiccant adsorption increases caused by too large ink, blank section from dirty and so on. Ink drying is too slow and can cause printing problems, adhesion, adhesion, solid lower; such easily scratched in the process. So the ink drying speeds should be fit, too fast and too slow is bad.
(5) the special structure of printing equipment
Due to differences in substrate, Tinplate printing auxiliaries also from offset printing. Tin does not dissolve in water, and no adsorption of solvents, inks require heat curing can be solvent of conjunctival curing. Hence the printing device equipped drying room you want in General. The tinplate printing line generally is about more than 50 metres in length, has the characteristics of large precision. In addition, tinplate printing machines is the use of magnets through double sheet control, materials of high hardness of tinplate also determines the printing process cannot use the advanced continuous iron structure, in the push section, and piling on the parts of the structure are different from paper offset printing press.