Author: Site Editor Publish Time: 2021-04-26 Origin: Site
At present, most printing methods are for decorative printing of flat or nearly flat substrates, such as film gravure printing, paper offset printing, etc.; screen printing has more substrates, which can print some irregular curved surfaces, such as plastic bottles; The adaptability of printing is better than that of screen printing, but the scope is too narrow. The common point of these printing methods is to use the flexibility of the substrate to transfer the graphics and text on the printing plate to the surface of the substrate by pressure. The transfer technology belongs to indirect printing. The transfer of graphics and text is not obtained by printing directly on the surface of the substrate. Therefore, there are many types of substrate shapes and materials that can be transferred. For example, the water transfer technology uses the pressure of water to transfer The technology of transferring and printing pictures and texts on the surface of objects.
Water transfer technology classification:
According to the realization characteristics of water transfer printing, it can be divided into water coating transfer and water mark transfer.
1.Water coating transfer
The so-called water coating transfer is to decorate the entire surface of the object, cover the original face of the workpiece, and be able to print patterns on the entire surface of the object (three-dimensional). This is its advantage; but the disadvantage is also obvious, that is, flexibility. When the graphic carrier is completely in contact with the substrate, it is inevitable that it will be stretched and deformed. Therefore, in fact, it is difficult for the graphic to be transferred to the surface of the object to be realistic.
Most of the printed graphics and texts of water transfer paper used for transfer are composed of decorative ink color blocks and simple repeating patterns, and there is no need to use fine photosensitive film for printing; water transfer films are mostly made of stretchable Manufactured from a good water-soluble film, the transfer film used for three-dimensional transfer is difficult to transfer and copy fine text and hierarchical images.
2.Water mark transfer
Water mark transfer is a process of completely transferring the graphics and text on the transfer paper to the surface of the substrate. It is very similar to the thermal transfer process, except that the transfer pressure depends on water pressure. It is a popular water transfer technology recently.
It can transfer a small area of graphic information on the surface of the substrate, which is similar to the printing effect of the pad printing process, but the investment cost is lower, the operation process is relatively simple, and it is very popular with users. The water mark transfer process does not require activation by an activator, avoids the pollution of organic solvents, and has obvious advantages in the production of handicrafts and decorations.
Water transfer material
Water transfer material refers to a printing film that is processed on the surface of a substrate that can transfer images and texts as a whole. The substrate can be a plastic film or a water transfer paper. This kind of printing film as a graphic carrier, its appearance should be a major advancement in printing technology, because many products are difficult to print directly.
With this carrier, people can first print the graphics and text on the easy-to-print carrier through mature printing technology, and then transfer the graphics and text to the substrate. Such as a certain height, relatively bulky, strange-shaped objects or small-area objects can use the transfer process. As far as the water transfer printing process is concerned, its adaptability is very wide, and there are almost no products that cannot be transferred. The transfer materials used for water transfer printing include water coating transfer film and water mark transfer paper.
(1) Water coating transfer film
Similar to the production process of the thermal transfer film, the water-coated transfer film is printed on the surface of the water-soluble polyvinyl alcohol film with a gravure printing machine using a traditional printing process. The base material of the water-coated transfer film has a very high expansion ratio and is easy to adhere closely to the surface of the object, which is the main reason why it is suitable for transfer on the entire surface of the object. However, the shortcomings of high flexibility are also obvious, that is, the graphics on the film surface are easily deformed during the printing and transfer process; secondly, if the transfer process is not handled well, the film may be broken. In order to avoid this shortcoming, we often design the graphics and texts on the water-coated transfer film to have no specific shape, and the repeated patterns will not affect the viewing after deformation. The water transfer film can be printed on a gravure printing machine to obtain a high elongation rate, and the printing cost can be greatly reduced. At the same time, the gravure printing machine has a precise tension automatic control system, which can print 4 to 8 colors at a time, and the overprint accuracy is relatively high. high. The gravure water coating transfer film uses water transfer ink. Compared with the traditional ink, the water transfer ink has better water resistance and the drying method is volatile drying.
(2) Water mark transfer paper
The base material of water-mark transfer paper is special paper, which is easily soluble in water. From a structural point of view, it is not much different from water-coated transfer film, but the production process is very different. Watermark transfer paper is to make transfer graphics and texts on the surface of the substrate by screen printing or offset printing.
Water transfer ink for screen printing is a special water-resistant ink, while offset water transfer ink can be replaced by general offset ink, and it is better to use special water transfer offset ink. It is difficult to make water transfer paper by screen printing, but the ink layer is very thick; the image and text of water transfer paper printed by offset printing can achieve higher resolution.