FOERFARANDE FOER FRAMSTAELLNING AV KEMISK PAPPERSMASSA OCH SAOLUNDA FRAMSTAELLD MASSA

摘要

The present invention relates to a process for producing a chemical paper pulp, wherein woodchips are digested at a defined temperature in an alkaline liquid containing a sulphur compound and the digestion process is stopped at a temperature at which the chips have a residual lignin content which corresponds to a kappa index of between 45 and 100 for resin-containing woods (soft-woods) and 30 to 50 for hard woods, and the chips thus treated are then mechanically defibrated and subsequently the digestion process of these defibrated chips is carried out with an alkaline solution which contains 0.1 to 1.5% of peroxide, relative to the weight of the dry defibrated material. The invention also relates to the paper pulp obtained by the claimed process.