A overview of the importance and application of pigments and dyes used in paper industry

Authors

1 Department of Wood & Paper Engineering, Gorgan University of Agricaltural

2 Depatment of Wood & Paper Engineering, Gorgan University of Agricaltural

3 Depatment of Wood & Paper Engineering, Tarbiat Modares University

Abstract

Colors of paper are determined by absorption properties of components. Almost all adsorption of light take place by colors and dyes. Currently varieties of colored paper are produced by adding amount of components of color and dyes. This study presents types of colors and dyes. Dyes and pigments are added to the paper for two main reasons, first is in order to produce a specific colored paper such as blue or pink and second reason is second to improve the appearance of white paper. Colors used in the paper including color pigments, acid dyes, basic dyes, dirt dyes and fluorescent dyes. The dyes and pigments used in paper industry, dirt dyes or inks are the most used because of high tendency to react with cellulose. Dirt dyes tend to react with the cellulose can be attributed to the low solubility of these materials. Aqueous solutions of dirt dyes are colloidal instead of solution. Fluorescent dyes are often added to increase the whiteness of the paper. In this paper, the methods of coloring paper and the factors are discussed. For coloring paper are used tow method, first is painting of pulp and second is surface coloring of paper which will be separately. Fundamental difference between these two methods is that the fibers are colored before or after the formation of a sheet of paper.