Tinplate printing is to print patterns on tinplate. It mainly USES the physical properties of water and ink to repel. With the help of printing pressure, the printing paper is transferred to the tinplate through blanket, which is the principle of offset printing. The process has special requirements for ink.
(1) Printing standards
Tinplate printing also USES water, ink to reject physical properties, under the pressure of printing by the transfer of the version of the blanket to the tinplate, is the principle of offset printing. It is precisely because of the special physical and chemical properties of tinplate D and the reprocessing characteristics of the print, its printing technology and the common offset printing technology is very different.
(2) Tinplate printing has special requirements for ink
(1) The ink requires good adhesion and mechanical properties
The ink on the tin plate has good adhesion and mechanical properties because it has to be cut, bent and stretched because it is eventually made into cans for food, toys, metal frames and cans for chemicals. In order to increase the ink adhesion, it is necessary to use white primer iron before printing. White is the main color of all colors and has high brightness. By adding high energy phase, the brightness of color phase can be improved and the gray level can be made.
(2) White ink requirements
Tinplate surface is silver white (or yellow), metallic luster, printing color graphics or text, need to paint the surface of the paint white or white, due to the ink coverage of the limit, black and white machine usually need to print twice white, white degree up to 75%. As an important indicator of tinplate printing product quality, white ink and primer require good adhesion, many high temperature baking will not turn yellow, high temperature steam will not fade. Tinplate primer can improve the adhesion of tinplate, white ink has good adhesion. Common primer is epoxy amino type, light color, no yellow for repeated baking, no aging properties and good flexibility impact and other process properties.
Color ink requirements
Color inks for tin plate printing have special requirements in addition to water resistance. Tinplate surface impermeable water and solvents, need to be dried, so the ink should be hot hardening. Color and durability of pigments are required. In addition to the basic properties of ordinary offset printing ink, according to the characteristics of iron should also have heat resistance, ink film adhesion, impact resistance, hardness resistance, cooking and light resistance.
(4) Ink drying process
It is tinplate printing ink drying is a complex physical and chemical process. Adhere to the reasonable control of ink drying speed, master the physical and chemical mechanism of ink drying, can effectively carry out rapid printing operation, to ensure product quality; Ink drying too fast, ink dry turn performance decreased, affecting the normal production. We through the ink attract, light ink, print, ink to dry on the surface of the roller, hinder the transfer of ink transfer print design and make the text layer to the outer drum dryer out of quantity increase, cause the adsorption of ink, ink drying too slowly, it difficult to transfer, adhesion, adhesion, strong degree is reduced, easy to damage in transport must be properly so that the ink drying speed, too fast too slow.
(5) Special structure of printing device
According to the different substrate, tinplate printing machine and offset printing machine's auxiliary mechanism is also different, tinplate insoluble in water, does not adsorb solvent, printing ink in order to make solvent volatilization, make conjunctiva hardening, need to be fired at high temperature. Printing and processing equipment usually requires a drying chamber. The whole length of tinplate printing automatic production line is generally about 50 meters, with high precision. In addition, the high hardness of tinplate material determines that the printing technology cannot be used in the advanced continuous iron transfer structure. The structure of the propulsion part, positioning part and piling part is different from the offset printing machine.
Classification and processing of printers
(1) Tinplate box printers are divided into two parts
Coating worker: A coating called 214 is applied to the inner layer of the tin to prevent corrosion. The substrate and the outer layer of the glass are also covered by the iron worker. The primer is designed to prevent color loss caused by direct contact between the colored coating and the sheet iron. Glazing effect is, one is waterproof, two is to prevent damage to the iron outer, three is to add luster to the appearance of tinplate, play a beautiful role).
Color printing: This is the process of making iron toner, which requires a high level of technical content, especially in controlling color depth.
Process: 214 coating is first applied to the inner layer of tinplate, and then put into the furnace to dry. After the iron is turned over, the outer tin is coated with a primer that may be pricked into IS with white. Then color printing is carried out. The color is put into the furnace to dry. The names of the coatings are 25(light oil) and white astigmatism.