The production process of coated paper is as follows: base paper selection→coating preparation→coating machine coating→drying→calendering or surface finishing→slitting or rewinding.

What are the types of coated paper?

Printing coatings can generally be divided into two categories: ordinary coated paper and special coated paper. Ordinary coated paper is to apply the paint on the surface of the base paper by ordinary coating method, after drying, it will be calendered, and finally cut or rewound into flat paper or roll paper, such as coated paper, matte paper, light weight paper, etc. Quantity coated paper, etc.; special coated paper refers to printing coated paper made with special coatings or special processing methods, such as cast coated paper (glass cardboard), embossed paper and matte coated paper.

Classification of coating process: Coating operations are divided into in-machine type and out-of-machine type according to the relationship between the coating machine and the paper machine, and divided into single-layer coating and double-layer coating according to the number of coatings. A coating machine is installed on the paper machine to make papermaking and coating continuously. Double-coated paper has better printability than single-coated paper, which can improve the quality of coated paper. There are mainly three types of coating machines used for coating operations: roll coater, air knife coater and knife coater.

Why do we need paper surface coating processing?After the paper surface has been calendered, the fibers on the paper surface are no longer loosely arranged, but have a certain degree of tightness, but the smoothness of the surface still cannot meet the requirements of high-grade fine printing. The surface uniformity of non-coated paper is poor, the ink color after printing is uneven, the gloss is low, and the fine dots cannot be restored, resulting in the loss of layers, the uniformity of the solid part of the image is reduced, and the effect of printing and reproduction is affected. Therefore, fine printing paper must be processed. Surface coating processing to further improve the surface properties of paper.、

The purpose of paper coating processing is to cover a layer of fine particles with good ink absorption on the surface of ordinary paper with unevenness and large pores formed by fibers, so as to obtain a good uniformity. and smoothness on paper.

Coating can also increase the gloss of paper, improve the stability and opacity of paper, and these characteristics will increase with the increase of coating amount.

What is the calendering effect on the surface of coated paper?

There is still a large number of fine unevenness on the surface of the base paper after coating, which cannot meet the smoothness required by printing, and does not have glossiness at the same time. Therefore, surface calendering treatment must be carried out, and the most commonly used calendaring method is super calendaring. The super calendar consists of multiple metal rolls and pulp rolls, and the paper is glossed by pressure and friction when it passes between the rolls. Matte coated paper does not require super calendaring, or only light calendaring.

What are the drying methods of coated paper?

After the paint is coated on the surface of the base paper, it cannot be dried directly with a dryer like uncoated paper, because the coating is still in a wet state, and direct contact drying will cause the paint to stick to the surface of the dryer. Generally, infrared drying or hot air drying should be used, or these drying methods should be used to dry to a certain degree of dryness, and then contact drying with a dryer.

What are the requirements of coated paper for base paper?

The quality of base paper has a very important impact on coated paper, and poor control will affect the performance of coated paper. In terms of base paper pulp, copperplate base paper mostly uses kraft wood pulp, of which 70% is hardwood pulp, and the rest is softwood pulp. For low-quantity, high-quality coated base paper, the amount of coniferous wood pulp should be correspondingly higher. In terms of strength, copper plate base paper should have high tensile strength and surface strength. In addition to changing the composition of pulp, measures such as increasing beating degrees and surface sizing should be adopted to improve the strength of base paper. In terms of surface performance, the base paper should not be too rough, nor too smooth. In addition, the absorbency of base paper should be moderate.