Paper and Printing Suitability and Related Processes (I)

First, printing represents the process of copying many sheets from a printing plate on a printing press. The printing industry is the largest concentrated consumer of paper products.

In order to provide paper products suitable for printing, manufacturers must understand and value the printer's requirements for paper. The two most important factors must be considered - "runability" and "printability."

1. Runability

The operation of the paper web on the printing press can be considered as a combination of all properties. Poor operation can cause web breaks, stoppages, or a decrease in the speed of the printing press, which has a large impact on the economic benefits of printing. The operability of the paper is manifested in strength, uniformity, no paper disease, and good mechanical conditions of the paper roll or paper.

Poor runnability appears on the press as break or relaxation tension, resulting in inaccurate wrinkling and overprinting. For newsprint, when the moisture content is high, its operability will be improved.

2, printability (printability)

Printability can also be referred to as print quality, but it is the effect of paper on the exact reproduction of the print. Paper properties: Whiteness, ink absorption, water opacity, color, gloss, smoothness, air permeability and degree of sizing are all important for printing. However, different printing methods require different papers. In general, coated paper is better than uncoated paper because of its smoothness, whiteness, gloss, and other properties. Therefore, it has a good appearance after printing.

Second, commercial printing has four main methods, which are classified as follows:

1. Letterpress printing is performed by a raised surface, also called relief printing. A lot of letterpress printing uses rotary presses, including printing of newspapers, magazines, and advertising flyers. Such printing is for paper. The smoothness, ink receptivity, and strength are highly demanded, and no paper breakage, wrinkling, or other problems that cause the printer to shut down are allowed. At the same time, the paper does not allow lint, powder fall, or blistering. There are soluble substances and friction substances.

2. The Lithograph is printed on a flat surface, also known as Planographic. Most of the lithographic methods are printed and printed on the plate to a blanket cylinder and then transferred to the substrate. This type of printing can also be referred to as Offset, commonly known as offset printing. Because the ink used for lithography is quite viscous, when the paper is peeled from the blanket, there is a large pulling force on the surface of the paper and a picking force is generated. Therefore, the paper used for printing in this way must be clean and free of paper. , And the surface strength is stronger, at the same time this printing method is easy to destroy the coating layer of the coated paper, and the smoothness of the surface of the paper is not required to be high, and the rough paper can also print good results.

3, Gravure (Gravure) to send ink to the substrate on the concave surface, also known as Intaglio. Gravureplate's remarkable feature is that the ink is directly applied to the substrate by the concave portion of the printing plate. The surface of the printing plate is flat, and only the graphic portion is concave. This printing method requires a relatively high level of paper smoothness. This type of printing is commonly used in cigarette pack printing.

4. Screenprinting This printing method is mainly used for the production of works of art. The amount of paper used is negligible. Therefore, it is not discussed here.