Detailed water transfer technology - classification

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 substrates are many, and irregular surfaces such as plastic bottles can be printed; The adaptability of India is better than screen printing, but the scope of coverage is too narrow. Common to these printing methods is the use of the flexibility of the substrate to transfer the graphics on the plate to the surface of the substrate by pressure. The transfer technology belongs to indirect printing. The transfer of the graphic is not achieved by directly printing on the surface of the substrate. Therefore, the shape and material type of the substrate that can be transferred are very large. For example, the water transfer technology uses the pressure of water. Graphic technology applied to the surface of the object for transfer printing.

(A) Water transfer technology classification

According to the realization of water transfer features, can be divided into water drape transfer and water mark transfer.

â–²1. Water drape printing

The so-called water drape transfer is to decorate the entire surface of the object, cover the original appearance of the workpiece, and can print the entire surface of the object (three-dimensional), which is its advantages; but the disadvantage is also obvious, that is, flexible When the graphic carrier is completely in contact with the substrate, it will inevitably undergo tensile deformation. Therefore, it is difficult for the graphic image actually transferred to the surface of the object to reach the degree of fidelity.

The printing graphics for the water transfer printing paper of the transfer method are mostly composed of decorative color ink blocks and simple repetitive patterns without the use of fine photosensitive film for printing; the water transfer film is mostly made of stretchable Good water-soluble film is manufactured, and the transfer film used for three-dimensional transfer is difficult to reproduce transfer and copy of fine text and hierarchical images.

â–²2. Water mark transfer

The water mark transfer is a process of transferring the graphic on the transfer paper to the surface of the substrate. It is like the thermal transfer process, but the transfer pressure depends on the water pressure. It is a popular water transfer technology. A small area of ​​graphic and text information transfer can be carried out on the surface of the substrate, which is similar to the printing effect of the pad printing process. However, the investment cost is lower and the operation process is relatively simple, which is very popular with users. The water standard transfer process does not require activation of the activator, eliminating the contamination of organic solvents, and has obvious advantages in the production of handicrafts and decorations.

Water transfer material

The water transfer material refers to a printed film that can be processed on the surface of the substrate and can transfer the graphic as a whole. The substrate can be a plastic film or a water transfer paper. This kind of printing film is used as a graphic carrier, and its appearance should be a major advancement in printing technology because many products are difficult to print directly. With this carrier, people can print images through sophisticated printing techniques. On the easy-to-print carrier, the graphic is transferred to the substrate. For example, a relatively high-heavy, cumbersome, grotesque article or a small area can be used in the transfer process. With regard to the water transfer printing process alone, its adaptability is very wide, and there are almost no products that can not be transferred. The transfer materials used for water transfer are water transfer film and water transfer paper.

â–²(1) Water drape transfer film

Similar to the production process of the thermal transfer film, the water drape transfer film is printed on the surface of a water-soluble polyvinyl alcohol film using a gravure printing machine using a conventional printing process. The substrate of the water drape transfer film is very high in stretchability, and it is easily adhered tightly to the surface of the object, which is why it is suitable for transfer on the entire surface of the object. However, it is also obvious that the large stretchability of the film is that the image on the surface of the film is easily deformed during the printing and transfer process. Secondly, if the transfer process is not handled properly, the film may be broken. In order to avoid this shortcoming, we often design the graphic on the water transfer transfer film to have no specific shape, and it does not affect the ornamental repeat pattern after deformation. The water transfer film can be printed on the gravure printing machine to obtain high elongation, the printing cost can be greatly reduced, and the gravure printing machine has an accurate automatic tension control system. It can print 4 to 8 colors at a time, and the overprint accuracy is better. high. The gravure water drape transfer film uses water transfer printing ink. Compared with the traditional ink, the water transfer ink has good water resistance and the drying method is volatile drying.

â–² (2) water mark transfer paper

The substrate of the water transfer paper is special paper, which is easily soluble in water. From the structural point of view, there is not much difference with the water transfer film, but the production process is very different. The water mark transfer paper is made by screen printing or offset printing on the substrate surface, as shown in Figure 1.

Screen printing water transfer ink is a special water-resistant ink, and offset water transfer printing ink can be replaced by ordinary offset printing ink. It is better to use specialized water transfer offset printing ink. Water-transfer printing paper is produced by screen printing, and the color registration is difficult, but the ink layer is very thick; the offset printing water-transfer printing paper can achieve higher resolution.

The use of inkjet printers to print water-based transfer paper is now the most popular method of production. Using printers and computers makes it easier to create personalized graphics according to their own preferences, and is therefore very popular. The production process of the water drape transfer film and the water standard transfer paper is shown in FIG. 2 .

(to be continued)