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Kraft paper adopts sulphate method of pulping (Kraft Process), with coniferous wood pulp as the main raw material, the fibre length up to 2-3 mm, lignin retention is more, so the texture is tough and tear-resistant. Unbleached kraft paper has a natural brownish-yellow colour, i.e. ‘brown kraft paper’, while bleached kraft paper is ‘white kraft paper’, and both types of kraft paper have high strength.

Sulfuric acid paper, also known as tracing paper or translucent paper, is widely used in various fields, ranging from fine drawing and printing work to industrial applications and artistic creations. Its unique properties, such as high transparency, excellent moisture resistance, and durability, make it an irreplaceable material in many areas. For example, in the printing industry, it is often used to make printing plates because its transparency enables the precise transfer of patterns. In the fields of architecture and engineering, it serves as an ideal medium for creating blueprints, allowing for the accurate replication of complex designs. Artists also favor it for its smooth texture and the ability to produce unique visual effects in artworks. So, how is sulfuric acid paper produced?

Acid-free paper, simply put, is paper that does not contain active acids. This paper is firm, strong and nearly neutral. The amount and color of this paper varies depending on the application, and it is a firm, strong, nearly neutral paper. When immersed in water, it produces a neutral or alkaline pH (7 or slightly higher). It is also lignin and sulfur free, which gives it good durability and makes it ideal for long-term storage of important items.

Why do circuit boards need to use sulfur-free paper? This has to start from the circuit board manufacturing process of some of the process. The main body of the printed circuit board is copper, which only reacts with oxygen in the air to generate dark brown cuprous oxide. In order to avoid oxidation, PCB in the manufacturing process there is a silver deposition process, so the PCB is also commonly known as silver-plated board. There is a silver deposition process in the manufacturing process, which has become one of the primary final appearance of printed circuit boards. However, there is a great affinity between silver and sulfur, silver in the air when encountering hydrogen sulfide gas or other sulfides, it is easy to generate very insoluble silver salts, resulting in yellowing and blackening of the product, that is, corrosion. Sulfur-free paper itself does not contain sulfur, will not react with the PCB surface of the immersed silver layer, the use of sulfur-free paper wrapped PCB b

Because news paper is different from SBS cardboard and some printing papers, it is not coated, is bulkier than cardboard after bleaching, has a lot of porosity on the surface, and has stronger wettability, etc., which is important in the use of ink. Both the application and coating aspects need to be comprehensively considered. For example, based on the analysis of the characteristics of news paper printing paper, some flexo printing is good, but it is not suitable to use a printing press for full-page on-site news paper printing. Because the surface of news paper is rough, the material is soft, and it has strong ink absorption, the color of the printed matter is dull, and printing will also cause the ink to pull off paper fibers (also called paper lint).