Printing and packaging is a branch of printing technology, which belongs to the category of special printing. Printing and packaging is mainly aimed at beautifying, recognizing and promoting commodities, and adopts printing methods and post-press processing technology. It is a kind of application of general printing technology. It is developed on the basis of general printing technology and forms a new system of printing industry. Following is an introduction to the printing and packaging process.
In offset lithographic printing, false color printing is often encountered, which is mainly manifested in the spot or weak, incomplete graphics or lines, and the gradual loss of poor reproducibility of images or points on the printing plate. There are many reasons for the inaccuracy of ink in printing process, which involves many factors, including paper performance, ink performance, plate quality, printing offset, printing pressure, printing press performance and printing process quality.
If in the printing process, paper, ink, stable performance, quality to meet the requirements of plate production, printing press performance is relatively stable, or ink printing false phenomenon, the main reason is the printing pressure problem。 In offset printing, the size of printing pressure directly determines the size of the ink in the transfer process。 If the printing pressure is not uniform locally, it will directly lead to the production of ink。
In offset printing, the compression deformation of rubber cloth is the fundamental guarantee of printing pressure, and the transfer of ink is the result of compression deformation of rubber cloth.
At the same time, the tension of action and printing pressure increase the number of rollers and the accumulation of compressive deformation stress of rubber cloth. The rubber cloth will become rigid, lose its original softness and high elasticity, and even appear bright or cracking signs on the surface of rubber cloth, leading to the process of printing pressure in uneven places.
On the other hand, because the cots are installed between the plate drum and the embossing roller, each small unit on the rubber cloth rotates once a week and contacts with two cots respectively。 Therefore, the force changes periodically, because the force applied on the rubber cloth changes periodically, which will lead to internal friction of the rubber cloth, leading to aging of the rubber cloth, affecting the uniformity of printing pressure, and possibly causing waste rubber cloth。 Especially in modern high-speed offset press, the higher the stress cycle frequency of the adhesive, the greater the internal friction produced by the adhesive, the shorter the service life of the adhesive, and the greater the impact on the printing pressure。
In addition to offset printing pressure and the power of blanket imprinting, blankets should also have a good printing board text and part of the text ink transferred to the surface of the substrate, that is, ink, ink release capacity, but aging blankets will change the ink transfer capacity, will also lead to ink.