ABSTRACT
The main purpose of bleaching is to increase the whiteness and the cleanliness of the bers to obtain better contrast and color reproduction in printing together with improved paper machine runnability. Other important ber properties such as water absorbancy can also be changed dramatically. The World production of fully bleached
General Overview .................................................................................................. 393 Chemical Overview ................................................................................................ 396
General Aspects ................................................................................................. 396 The Structure of Residual Lignin ...................................................................... 397 Nucleophilic Reactions ..................................................................................... 398
The Peroxide Stage ....................................................................................... 398 The Alkaline Extraction Stage ...................................................................... 399
Electrophilic Reactions ..................................................................................... 399 The Oxygen/Hydrogen Peroxide System .....................................................400 The Ozone System........................................................................................ 401 The Chlorine Dioxide/Chlorine System .......................................................402
