What is the role of colorants in paper? Even the bleach […]
What is the role of colorants in paper?
Even the bleached pulp fibers are slightly yellow or gray, because the lignin contained in the pulp fibers tends to absorb purple and blue light with a wavelength of 400-500 nm. The more lignin content in the pulp, the more The darker the color. Therefore, in order to make the paper have a higher whiteness, a blue-violet or red-blue dye is often added to the bleached pulp. The production of colored paper must also be dyed.
What are the ingredients of the pigment?
Colorants are pigments and dyes used for paper dyeing and tinting. Most of the pigments are inorganic, most of them are insoluble in water; the dyes are divided into natural dyes and synthetic dyes. Currently, synthetic dyes have completely replaced natural dyes. Most of the dyes are soluble in water or chemically soluble in water.