Gray bottom white board paper: The base color is gray, the front is white-coated surface

White board paper with gray background is generally called white board, powder gray, gray background white, and gray copper. The base color is gray, and the front is a white coated surface, mainly used for printing and packaging.

Due to the difference in material and thickness of the coated surface, gray-bottomed whiteboards are divided into multiple grades. The common grades are A grade, B grade, C grade, E grade, F grade, descending from high to low, and F grade is the worst. It is called uncoated paper or lightly coated paper. The gray-bottom whiteboard is measured in tons, and each level is divided into multiple grams, which is divided into 200 grams, 230 grams, 250 grams, 270 grams, 300 grams, 350 grams, 400 grams, and 450 grams. The gram weight here represents per square meter per gram.

The best one type of the top white liner paper is using the coating machine line to produce.

Due to the relatively uniform fiber structure of coated whiteboard paper, the surface layer has filler and rubber components, and the surface is coated with a certain amount of paint, and has been processed by multi-roller calendering, so the texture of the paperboard is relatively compact and the thickness is relatively uniform. The surface is generally white and smooth, with relatively uniform ink absorption, less powder and hair-loss on the surface, stronger paper quality and better folding resistance, and its water content is generally around 8%. 

There is a certain degree of flexibility, which will have a certain impact on printing. The difference between whiteboard paper and coated paper, offsets paper, and letterpress paper is that the paper is heavy and the paper is relatively thick. The pulp of whiteboard paper is generally divided into surface pulp (surface layer), second layer, third layer, and fourth layer. The fiber ratio of each layer of paper pulp is different, and the fiber ratio of each layer of pulp depends on the The quality of papermaking varies. 

The first layer is the surface pulp, which requires high whiteness and certain strength. Usually, bleached kraft wood pulp or partially bleached chemical straw pulp and white paper edge waste paper pulp are used; the second layer is the lining layer, which plays the role of isolation The role of the surface layer and the core layer also require a certain degree of whiteness, usually with 100% mechanical wood pulp or light-colored waste paper pulp; the third layer is the core layer, which mainly acts as a filling to increase the thickness of the cardboard and improve the stiffness. Generally, mixed waste paper pulp or straw pulp is used. 

This layer is the thickest, and cardboard with high weight is often used to hang-pulp several times in several mesh slots; the last layer is the bottom layer, which has the functions of improving the appearance of the cardboard, increasing its strength, and preventing curling. Using high rate pulp or better waste paper pulp as raw material, the color of the bottom surface of the cardboard is mostly gray, and other bottom colors can also be produced according to requirements.