Paper category and basic parameters analysis

Paper is an important part of printing supplies. It's good or bad determines the stability of the printing process and the quality of printed matter.

Paper can be divided into three types in printing: Newsprint is quantified at approximately (49-52g/m2), which is mainly used for printing newspapers. Because the newsprint paper pulp has a large amount of lignin and impurities, the newsprint surface is yellowish, and Should not be placed for a long time, it is easy to become brittle, and the quality of the prints is usually only printed in monochrome on newsprint. Offset paper contains less lignin and impurities, so the offset paper has small flexibility, uniform ink absorption, good smoothness, tight and opaque texture, good whiteness, strong water resistance, and high printing quality. Relatively fine print printing paper. The usual quantification is (50-180g/m2). Coated paper quantification is generally (150 ~ 280g/m2), used for high-grade, exquisite print paper. Coated paper has single-sided coated paper, double-sided coated paper, matt coated paper, and coated copper coated paper. According to the quality is divided into A, B, C three. The main raw materials of coated paper are copperplate paper and coatings. The requirement for the copperplate paper is uniform thickness, low elasticity, high strength, and good water resistance. The paper surface is not allowed to have paper spots such as spots, wrinkles, holes, etc. The coating used for coating consists of high-quality white pigments (such as kaolin, barium sulfate, etc.), adhesives (such as polyvinyl alcohol, casein, etc.), and auxiliary additives. of. The paint with high liquidity and high solid content is thinly and evenly coated on the base paper by a coater, then dried, rolled into a roll on a reel, and then sent to a super calender for pressing. Light finishing, final cut, paper selection, packing.

Paper is a large part of the printing cost. With the rise in global pulp prices, paper prices have also soared. Make printing companies, printing costs are high. Choosing the right paper and reducing the paper consumption during the printing process is an efficient way to increase the profits of the printing industry.

When buying paper it is necessary to take into account some of the parameters of the paper:

1. Whiteness: Refers to the degree of whiteness on the surface of the paper. Magnesium oxide is usually called 100% white, and the whiteness of paper is relative to this 100% white. Papers with high whiteness in printing are generally used for relatively fine prints, and relatively large prints with high whiteness have relatively large differences in print quality, rich print layers, and good color reproduction. When the printing factory purchases, it should determine the required whiteness range according to the printing effect required by its own printing business. The paper with high whiteness has relatively low internal impurities and the price will be relatively high.

2. Quantitative: refers to the weight of paper per unit area, also called gram weight. Different prints require different amounts of paper. In general, newspapers generally use low-volume paper for printing, and high-volume paper is generally used for packaging and printing. The higher the amount of paper, the greater the paper tightness and the higher print reproduction ability.

3. Smoothness: The time required for a certain volume of air to pass through the gap between the specimen surface and the glass surface under a certain pressure under a certain degree of vacuum. Smoothness is an index to evaluate the characteristics of the surface roughness of paper or paperboard. It is very important for printing paper. It affects the uniform transfer of printing ink. The smoothness of paper or board is affected by factors such as fiber morphology, degree of pulp freeness, weaving methods for papermaking nets and felts, wet press pressure and the presence or absence of calendering, filling and coating.

4. Surface tension: also known as pulling strength. It is the strength of separation of the paper coating layer and the interior of the paper. For some papers, due to too many additives, there are phenomena such as pulling hair and falling paper in the printing. This is caused by the low surface tension of the paper. When purchasing paper, pay attention to the surface tension of the paper.