Abrégé

A method of manufacturing a multilayer fibrous product. The product comprises at least two overlapping layers, each of which has a different fiber composition, and in the production of the product, chemical short stock is used at least partly. In the method, short stock is brought to a screening stage where fines, which pass a screen having an average hole size of 0.2-1.5 mm, are separated from it, in order to prepare at least two fiber fractions having different fiber compositions, and the fractions generated are recovered and included in different layers of the same fibrous product. With the invention, it is possible to screen an initial material and form a product which has better properties than a corresponding product, the initial material pulp of which has only been refined.

Classes IPC  ?

• D21H 27/38 - Papier particulier non prévu ailleurs, p.ex. obtenu par des procédés multi-étapes à plusieurs jets au moins une des feuilles ayant une composition fibreuse différente de celle des autres feuilles

Abrégé

Method for the production of mechanical or chemi-mechanical pulp as raw material for paper or cardboard. According to this method, the pulp is fibrillated and the fibrillated pulp is bleached in alkaline conditions. According to the present invention, the pulp is screened to separate the reject from the accept, at maximum approximately 60% of the total amount of pulp is separated as the reject, the reject is bleached separate from the accept, and, after that, the bleached reject is remixed with the accept. When operating according to the present invention, the strength of the pulp increases and the energy used for refining is reduced, which is seen both in the refining of the reject and in the post-refining of the final mechanical pulp.

Classes IPC  ?

• D21C 9/16 - Blanchiment avec des per-composés
• D21B 1/12 - Matières premières fibreuses ou leur traitement mécanique par division des matières premières en petites particules, p.ex. fibres par l'emploi de vapeur
• D21D 5/02 - Epuration de la pâte