The color in pulp mainly comes from

In pulp, color mainly comes from lignin and extracts, and there are two bleaching methods:

1,' Dissolved Lignin Bleaching', using a suitable bleaching agent, dissolving Lignin by oxidation to achieve the purpose of bleaching. Such as chlorine bleaching, hypochlorite bleaching, chlorine dioxide bleaching, chlorine peroxide bleaching, etc. This method is often used in the case of high whiteness of pulp. Chemical pulp is often bleached in this way.

2. "Bleaching with lignin", which not only retains lignin, but also decolours chromophores. The loss of bleaching in this way is very small, and the characteristics of pulp are retained. Such as dithionite bleaching and sodium borohydride bleaching. This method is often used to bleach high-yield pulp.

The raw materials of modern papermaking include plant fibers (wood, bamboo, grass, etc. ), mineral fiber (asbestos, glass fiber, etc. ), other fibers (nylon, metal wire, etc. ), and polymer materials obtained by petroleum cracking.

At present, the paper used for writing, printing and packaging is still mainly made of plant fibers.