Publishing printing paper standard (on)

In recent years, the rapid development of China's paper industry, the total output of paper and paperboard, total consumption has ranked second in the world, and formed a complete set of standardized systems. Among them, the national standardization law, measurement law and product quality law are the three basic laws that must be followed in the production and sale of paper products.
China's paper industry standards include national standards, light industry standards, and corporate standards. As far as the application field is concerned, there are product standards, product performance test method standards, and product test environment atmospheric conditions standards, as well as paper quality supervision and inspection papermaking special measurement instruments Light Industry Department department measurement verification procedures. According to China's papermaking industry standardization system table, published printing paper is divided into two categories: non-coated paper and coated paper. Publishing of large-scale papers used in the printing industry, such as newsprint, offset printing, offset printing, letterpress printing, etc., are non-coated printing papers; coated papers, low-quantity coated papers, cast-coated papers, etc. . The optical properties of the paper are based on the optical principle of the test. Whiteness, color, and opacity are the diffuse reflection characteristics of the paper. Gloss and print gloss are mirror reflection characteristics of the paper. This article focuses on the optical properties such as whiteness, chromaticity, opacity, etc., of published printing paper and its testing standards.
Optical performance 1, whiteness As we all know, white paper can truly and objectively reflect all the colors of printed graphics, improve the contrast and sharpness of the text, make the copy colorful, achieve the effect of illustrations. The higher the paper whiteness, the more significant this effect is. However, the whiteness should not be too high, otherwise the reflected light is strong, and the visual nerve stimulation is too strong, which can easily cause visual fatigue. Therefore, the higher the whiteness of the printing paper is, the better, and the whiteness value of the printing paper for different purposes is also not the same. It is reported that China Youth Children's Publishing House, from the perspective of protecting children's eyesight, many textbooks use low-white paper, and some books even use bean green and light yellow writing paper. Heilongjiang Children's Publishing House also reduced the whiteness of the supporting books to 76%-85%. The Ministry of Education stipulates that the whiteness of children's textbooks should be 75% to 76%.
Although the printing and printing papers are basically white or nearly white, they all have color casts, some are bluish and some are reddish. The purpose is to make visual judgments look more white, but it also varies from person to person. In any case, the paper supplied in the same batch should have the same whiteness, uniform color tone, and no obvious color difference, so as to avoid stratification in the color of cuts in binding printed volumes.
2. Opacity The value of the opacity of printing paper directly affects the print penetration of printed products. All kinds of printing paper must have sufficient opacity, otherwise, it will easily lead to printing failures.
3, gloss Gloss of print and paper mirror reflection characteristics are closely related. The print gloss of a paper refers to the fact that it is printed in situ on a paper sample under standard conditions using a standard glossy ink, and the dryness of the printed area is measured and expressed as a percentage. General paper gloss is high, the gloss of the printed matter is high, and the printed matter is vividly illustrated and colorful. Such as coated paper gloss and printing gloss minimum required 60% and 88%.
The optical performance standards of each paper Newsprint International GB/T 1910-1999 divides newsprint products into superior products, first-class products and qualified products.
a) Brightness. Brightness, also known as whiteness, standard three levels of product brightness value of not less than 52%, 50%, 48%;
b) hue check. It is stipulated that the three grades of products are based on L*≥80.0, a*=-2.0 to +2.0, and b*<10.0 as the basis for controlling the color tone of each plant.
c) Color difference ΔE*. The color difference ΔE* of the same batch of paper. Excellent products and first-class products should not exceed 2.5 and 3.0 respectively, and no qualified products are required. (To be continued)