Method for bleaching paper pulp with organic peracids followed by peroxide and sodium hydroxide
AssigneeCompagnie Industrielle de la Matiere Vegetale
InventorsMichel Delmas, Gérard Avignon
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Abstract
The invention concerns a method for bleaching different types of paper pulp in two steps at atmospheric pressure and at a temperature not higher than 100 DEG C. The first step consists in contacting the unbleached paste with a mixture of paracetic acid and performic acid. The second step consists in treating the bleached pulp derived from the first step, with a solution of soda and hydrogen peroxide. The resulting pulps exhibit a high index of whiteness and a degree of polymerisation close to unbleached pulps. The method is environmentally safe and non-polluting.
Claims14
A method for bleaching raw chemical paper pulps with organic peracids, wherein the method is carried out in two steps at atmospheric pressure and at a temperature of less than or equal to 100° C., and consists essentially of:
- a first step of bringing the raw chemical paper pulps into contact with a mixture consisting of peracetic acid and performic acid so as to obtain a reaction medium having a water content of less than or equal to 15% by weight;
- and
- a second step of treating the paper pulps obtained, after mechanical separation of the reaction medium obtained at the end of the first step, with a solution consisting of sodium hydroxide and hydrogen peroxide.
Dependencies are inferred from the claim text.