Encyclopedia of printing: A common inventory of eight special printing methods (C)

Fifth, embossing imprint

Embossing and embossing, no ink, but the use of pressure on the printed matter has been printed, white or cardboard out of a variety of concave and convex patterns and patterns, commonly known as "roll bump."

We often see many signs, patterns such as bottle tags, trademarks, and paper boxes, envelopes, etc. These products are made by embossing and embossing methods. The reproductions are vivid and beautiful, and have a strong three-dimensional effect.

Embossing can be divided into two types, one is embossing, and the other is pressed steel wire.

1. Pressure relief. The embossed gravure is made by etching or engraving, and the plate is a copper plate or a steel plate.

The gravure copper (steel) gravure is glued onto the metal bottom plate of the flat press, the printing plate is leveled, and the yellow paperboard is pasted on the platen to correct the pressure; then the glue, gypsum powder and water are mixed into the gypsum. Paste, quickly spread a layer of gypsum paste on a flat board with yellow cardboard, slightly flatten it, cover it with a piece of tissue paper, and then cover it with a thin layer of plastic film so that gypsum powder is not embedded in the plate pattern. in. After that, the machine can be manually operated and the pressure is gradually increased. Two pressures are printed on the front and back. The pressure is small for the first time and the pressure is properly applied for the second time. After the gypsum paste is completely dried, it is made into a plaster embossed. Letterpress.

The printed matter is placed between a steel (copper) gravure plate and a gypsum relief plate, and embossing can be performed with greater pressure. The printing method is basically the same as the general three-color printing method, but the pressure requirements are larger.

If the printing paper used is thicker and harder, a hot pressing method can be used, which is to use electric heat to make the metal gravure generate heat and impress at the same time, so as to obtain a better quality product.

2. Press steel wire. Also known as die-cutting process. Some of the edges of color prints, such as certain trademarks, bottle labels, and other fine prints, are made into arc-shaped edges according to design requirements, and are generally not cut by ordinary cutters. Instead, it is pressed by the press wire method.

Six, plastic printing

Plastic printing is the process of printing text or images on plastic products such as polyethylene, polyvinyl chloride, polypropylene, and other vinyl films.

The plastic surface is relatively smooth, and the performance of absorbing ink is extremely poor. The ink adhered to the plastic surface after printing is completely dried by the oxidized conjunctiva, unlike the general paper that is accompanied by absorptive drying at the same time as the oxidized conjunctiva; the ink is often not printed or Marking is still easy to wipe off after a few days after printing, and this phenomenon is one of the biggest characteristics and problems in plastic printing. For this reason, the ink for plastic printing should have high viscosity, strong adhesion, and can make the ink molecules firmly adhere to the plastic surface and easily oxidize the conjunctiva and dry.

Before printing plastic films such as polyethylene and polyvinyl chloride, surface activation must be performed. To enhance the adhesion of the ink. Commonly used methods include chlorine treatment, oxidation treatment, and corona discharge treatment.

The plastic printing plate, pad printing and printing process operations are the same as ordinary relief printing. However, due to the characteristics of plastics, the printing pressure is slightly larger than the general letterpress printing, the imprinting is to be real, and the brushing ink is required to be good to help the ink adhere to the surface of the plastic and make the imprinting firm and beautiful.