M-real Oyj

Maija Pitkänen

Petri Silenius

Markku Leskelä

Soili Hietanen

Outi Aho

Kristiina Manninen

Marko Pekkola

Isto Nikamaa

Pirita Suortamo

Auli Laurila-Lumme

Ole Nickull

Kai E J Vikman

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.

Process for producing mechanical pulp suitable for paper or cardboard making

A filler comprising cellulose or lignocellulose fibrils on which light-scattering material particles have been deposited, and a process for the manufacture thereof. In the filler according to the invention, an alkyl derivative of cellulose, such as CMC, has been sorbed to the fibrils. Such a filler can be prepared from a source material containing cellulose or lignocellulose fibrils by first forming a fibril suspension, into which there are fed source materials forming an inorganic or organic salt that, when precipitating, forms a light-scattering pigment. The filler according to the invention has very good strength properties; in particular, good bond strength is achieved by means of it. The concentration of mineral pigment in paper can be increased and, furthermore, the grammage of paper can be lowered without the other important properties of the paper deteriorating.

Filler and a process for the production thereof

Growing community of inventors

Jyväskylä, Finland

Maija Pitkänen