Patent ID: 8454799

Claim:
A process for producing a paper or a solid board, the process comprising: i) suspending a)-c) in water to form a fiber suspension: a) a chemical pulp A; b) an oxidized pulp B in which, by oxidation of at least one conventional pulp selected from the group consisting of a recovered paper pulp, a mechanical pulp and mixtures thereof, from 1 to 500 mmol of carboxyl groups and from 1 to 200 mmol of aldehyde groups per kg of the conventional pulp have been introduced; and c) a further conventional pulp C other than the chemical pulp A and the oxidized pulp B; ii) optionally adding a customary additive, filler, or both; and iii) draining a resulting aqueous fiber suspension in a paper machine to form a paper or a solid board, wherein: a total amount of the chemical pulp A and the oxidized pulp B is from 30% to 80% by weight of an entire pulp mass in the fiber suspension; a total amount of the chemical pulp A, the oxidized pulp B, and the further conventional pulp C is at least 70% of the entire pulp mass in the fiber suspension; and said amounts are measured as oven dry materials wherein a molar ratio in the oxidized pulp B of the carboxyl groups introduced to the aldehyde groups introduced is greater than 1:1; and a paper or a solid board produced exhibits greater dry strength properties without incurring a significant increase (to an extent which has no appreciable effect on later repulping) in wet strength properties, relative to a paper or solid board produced from a pulp composition which does not comprise the oxidized pulp B.