Talking about the classification of transfer printing and the suitability of printing ink printing

As a big country of production, whether it is textiles or other small commodities, it is a large industry in China, with large quantities and many varieties. Transfer printing has broad prospects for development in China.

Transfer printing refers to the appearance of irregular undulations on the surface of some substrates, or objects that have already been molded, or a printing method that is not convenient for printing on a printing press such as a soft material. In order to be able to print images and texts on the surfaces of these substrates, the images and characters must be first printed on a material called an intermediate transfer carrier, and then the carrier must be subjected to certain methods such as heating and moistening. Wet, pressure, etc. transfer them to the substrate and finally form the print.

Transfer printing is categorized according to the transfer method. There are direct printing and indirect printing. Direct pad printing is to use a pad printer to suck the ink on the intaglio face on a special pad printer, and then transfer it to the substrate. It is mostly used to surface irregular irregular containers, small accessories and toys. And tableware and so on. Indirect printing is the use of special transfer paper or transfer film first printed on the pattern, and then transferred to the substrate, mostly used for ceramic decal printing, textile printing, product label printing. According to the transfer technology, wet transfer, thermal transfer and pressure transfer are classified.

The application of transfer printing is very extensive. The first is that its substrates are not only physically diverse, but also varied in materials. Some of the irregularly shaped containers, children's toys, furniture, trademarks, and other types of ceramics, glass, plastics, textiles, and leather are widely used. And other daily necessities printed. Transfer printing can almost compensate for the printing of various materials that cannot be printed on many curved surfaces. In addition to printing directly on a dedicated pad printing machine, other transfer printing is off-line printing, ie, the intermediate transferring body and the printing body are independent and do not affect the respective processing. Because the transfer printing can be applied to flat or irregular uneven surfaces, such as printing on various moldings with multi-segment, multi-curved surfaces and polygonal flat surfaces, and can realize multi-color fine printing, it also plays an important role in the field of packaging and printing. effect.

Direct pad printing is the use of the principle of gravure printing, that is, after all the gravure surface is coated with ink, with a scraper to engrave the convex part of the blank ink, leaving only the concave part of the pattern of ink, and then made of silicone rubber The print head applies pressure to stick out the ink before it is transferred to the substrate. Pad printing machine is the main equipment for pad printing, in which the pad printing head plays the role of transfer. Therefore, pad printing plate, pad printing head and pad printing ink constitute the three major elements of the pad printing process. The pad printing process is The pad printer finishes automatically. Under the premise of the printing plate and the printing head, the quality of the printing ink has become a decisive factor in the printing effect.

There are several printability requirements for the performance and requirements of pad printing inks:

(1) Suitable drying speed. In general, pad printing ink is a type of quick-drying ink mainly based on volatile drying, but relatively speaking, pad printing ink has two kinds of slow drying and quick drying, that is, the general printing of drying in 2 ~ 5S is faster Dry-type pad printing inks, those drying above 5S are slow-drying pad printing inks.

(2) Better deinking ability. This deinking ability refers to the deinking ability of the pad ink to the pad, that is, the ability of the ink to transfer from the pad to the substrate, and of course also relates to the deinking ability of the pad.

(3) Good ink adhesion. Due to the wide range of pad printing and the variety of printing materials, it is required that pad printing inks have good adhesion to different substrates. In addition, as a pad printing ink, it is also required that the printing head and the printing plate are not corroded. Therefore, the solvent used in the moving ink is usually butyl acetate, cyclohexanone, and turpentine.

Indirect pad printing is used for printing materials that are not suitable for printing on the surface of direct printing presses. For example, some plane, three-dimensional, curved surfaces, and other materials and their products must be printed on a transition carrier and transferred to other substrates. A printing method on the material. There are many indirect transfer printing methods, including decal printing, thermal transfer printing, warm transfer printing, pressure transfer printing, and self-adhesive label printing. The printing methods on this transfer transfer body include plain printing, embossing, and gravure printing. In recent years, with the continuous improvement of screen printing technology, the increase in the variety of screen printing materials, and the improvement of equipment, a transfer technology using silk screen printing has emerged, providing more printing methods for indirect transfer printing. The earth has expanded; the scope of application of transfer printing. The following focuses on the thermal transfer of fabrics.

In addition to printing and dyeing silk screen printing technology, fabric textile products can be directly printed on the surface, in order to improve the printing effect, increase the three-dimensional image, there are many methods of thermal transfer printing, such as sublimation diffusion transfer transfer, melting method Transfer, stripping transfer, etc. The thermal transfer is mostly applied to the transfer of textile products, such as clothing, shoes, hats, and luggage. The substrate for thermal transfer is paper (or film) coated with a release agent. This kind of paper has a certain adsorption power to the ink, more importantly, it has certain deinking ability and can withstand temperatures around 150°C. First, select the printing method according to different requirements, such as embossing, flat printing, gravure printing, and screen printing, either, and then make the corresponding printing plate and apply thermal transfer paper (or film) to the printing machine Multi-color printing, printing a layer of heat transfer adhesive, in order to spare. During transfer, the transfer paper printed and coated with heat transfer adhesive is tightly attached to the textile on the transfer machine, at a temperature of 150 to 170° C. under a pressure of 0.1 to 0.25 Kgf/cm 2 (9.8 to 24.5 KPa). With 5~10S hot pressing, the printed pattern can be transferred from the paper surface to the fabric and firmly attached to the fabric. For the thermal transfer glue that must be used for thermal transfer, according to the author's understanding, there is no production in the country, or the quality cannot meet the requirements, and it still needs to rely on imports.