The present invention relates to an improved process for producing chemical cellulose pulp wherein biopolymers are added immediately before, during or after a bleaching step, depending on pulp characteristics and on process conditions used. The biopolymers according to the present invention are starches chemically modified by an etherification reaction. This treatment results in a differentiated pulp having improved physical, chemical and mechanical properties when compared with cellulose pulps obtained by traditional processes. The use of said biopolymer alters the relations between important pulp properties rendering their application in papermaking process advantageous. This differentiation increases the possibilities of use and also of new applications, including for the substitution of pulps produced from other cellulose sources. Thus, the present invention also relates to methods of making paper, such as printing, writing, decorative, special or tissue-type papers, through the use of the cellulose pulps modified by the above process.

A method is disclosed for dewatering of sludge from a pulp, paper or board making process, such as deinking sludge, including obtaining of an aqueous sludge including an aqueous phase and a fibre material suspended in the aqueous phase. The sludge is subjected to a pre-thickening step, where a first part of the aqueous phase is removed from the sludge and to a pressing step, where a second part of the aqueous phase is removed from the sludge, thereby obtaining a dry pressed sludge. Before or at the pre-thickening step a polymer composition having a charge density of at the most 1.7 meq/g, preferably at most 1.5 meq/g, more preferably at most 1.1 meq/g, is added to the sludge.

A wet-laid fibrous product is provided that comprises recycled cellulosic fibers, cellulose ester staple fibers, and residual recycled ink, where the fibrous product has less ink content compared to the ink content for a 100% cellulose comparative fiber wet-laid product, when processed under similar conditions. The wet-laid fibrous product can be formed from a deinked recycled paper pulp slurry, the pulp slurry comprising recycled cellulosic fibers, cellulose ester staple fibers, and ink. A deinking process for the slurry is also provided.

The present specification discloses papermaking additive compositions, articles of manufacture, containers or kits comprising such compositions, and methods and uses to increase separation of cellulose fibers from a pulp, to remove one or more impurities and/or one or more contaminates from a pulp and/or a paper material and to remove an ink from a pulp and/or a paper material.

A process for the deinking of a coated paper or paperboard is disclosed, the process comprises a step of providing a coating layer comprising a calcium- or magnesium-exchanged clay which is deposited on the paper or paperboard before the ink layer. In a further step said calcium- or magnesium-exchanged clay is activated and the paper is subsequently treated with water.

The ink composition comprises pigment particles and a stimulus responsive dispersing agent for dispersing said pigment particles in a protic polar solvent, for instance for inkjet printing, which stimulus responsive dispersing agent comprises an anchoring part for anchoring to said pigment particles, a stimulus responsive part as shown in formula (XXa) or (XXb) and a hydrophilic part for solvent stabilization of the pigment, wherein the stimulus responsive part upon exposure to a stimulus initiates decomposition of the stimulus responsive dispersing agent. The paper with the printed ink can be deinked in an industrial deinking process. ##STR00001##

Provided is a method for producing paper and a pitch removal agent that can remove pitch efficiently. A pitch removal agent having an average polymerization degree of 300 to 2500, a saponification index of 70 to 88 mol % and satisfying, when the absorbance at a wavelength of 490 nm is designated as y (Abs) and the saponification index as x (mol %), the Numerical Formula (A) below is added to a pulp slurry during production of paper using waste paper in the step of deinking the waste paper by floatation and/or a step earlier:
y=0.0297x+b(A) (wherein, 70x88 and 2.80b3.03).

A processing apparatus includes a deinking material supply portion that supplies a deinking material to defibrated fibers, and an agitating portion that agitates a mixture of the deinking material and the fibers. The agitating portion includes a chamber and a rotary blade that rotates in the chamber.

A method of pulping wastepaper includes providing a pulping vessel with a rotor and at least one flow sensor adapted to measure slurry flow within the pulping vessel. The pulping vessel is charged with wastepaper and water to form a slurry, the amounts of wastepaper and water being present such that the slurry has consistency in the range of from 10% to 30%. The wastepaper charge in the pulping vessel is pulped at a pre-selected power level while monitoring poloidal slurry flow in the pulping vessel; and from time-to-time, water may be added to the pulping vessel when the poloidal flow falls below a predetermined lower threshold flow value in order to reduce viscosity and thereby restore poloidal flow within the pulping vessel. Doppler velocimetry is a preferred method of monitoring pulp flow. In a particularly preferred construction the rotor has a variable power drive. The inventive method is especially useful for making high quality, high brightness furnishes from wastepaper which varies from batch to batch.

Methods of improving dewatering efficiency, increasing sheet wet web strength, increasing sheet wet strength, and enhancing filler retention in a papermaking process are disclosed. The methods improve the efficiency of drainage aids, wet web strength aids, and/or wet strength aids by coating at least some of the filler particles with a material that prevents the filler materials form adhering to a those additives.