摘要:
A bleached softwood kraft pulp fiber with high α-cellulose content and a low CED viscosity is provided, A surfactant treated fiber useful in the production of chemical derivatives is also described.. Methods for making the kraft pulp fiber and products made from it are also described.
摘要:
L'invention a trait à un procédé de délignification et blanchiment de pâte à papier, comprenant une étape de mise en contact de la pâte à papier avec du peroxyde d'hydrogène et avec un complexe cuivre-ligand cyclique, le ligand cyclique ayant la formule (I) : dans laquelle chaque groupement R est indépendamment choisi parmi l'hydrogène, un groupement alkyle en C1 -C6 linéaire ou ramifié, le groupement pyridin-2-ylméthyle et le groupement CH 2 COOH; chaque groupement R 1 et R 2 est indépendamment choisi parmi l'hydrogène, un groupement alkyle en C1 -C4 linéaire ou ramifié et un groupement alkylhydroxy en C1 -C4 linéaire ou ramifié; et chaque n vaut indépendamment 2 ou 3.
摘要:
The present invention relates to a method and use therein for inactivating hydrogen peroxide decomposing enzymes in the production of recycled fiber pulp and/or mechanical pulp comprising providing solid peroxygen to an aqueous process for fiber production.
摘要:
A modified kraft pulp fiber with unique properties is provided. The modified fiber can be a modified bleached kraft fiber that is almost indistinguishable from its conventional counterpart, except that it has a low degree of polymerization (DP). Methods for making the modified fiber and products made from it are also provided. The method can be a one step acidic, iron catalyzed peroxide treatment process that can be incorporated into a single stage of a multi-stage bleaching process. The products can be chemical cellulose feedstocks, microcrystalline cellulose feedstocks, fluff pulps and products made from them.
摘要:
The inventive process converts cellulosic biomass into a gel-like state that is readily hydrolyzed by appropriate enzymes. First the biomass is mechanically reduced in size. The biomass is then mixed and kneaded with an aqueous solution of a hydrophilic polymer that acts as a conditioning agent or as a co-solvent. During mixing the cellulose (and hemicellulose) in the biomass swells and becomes hydrated forming a viscous gel-like material. The processed material can then be thinned through the addition of water whereupon hydrolytic enzymes are mixed into the material and rapid hydrolysis into free sugars takes place. Dextrins are effective hydrophilic polymers for conditioning biomass. Polyvinyl alcohol is a particularly effective conditioning agent for use with biomass when converted into a viscous gel by adding borate ions.
摘要:
The invention relates to a process for making paper, wherein a pulp suspension, which comprises mechanical pulp, is thickened in a dewatering device and is thereafter diluted with water and pumped to a storage tank, then diluted again and made in to paper. According to the invention, the pulp suspension is subjected to an acid - base treatment after the dewatering device. The pH of the suspension is first reduced with a strong acid by 0.5 -4 pH units to a pH between 4 and 6 and then the pH of the suspension is increased with a weak base by 0.5 -3 units to a pH below 8. The invention also relates to the use of an acid - base treatment in a process for making paper, wherein a pulp suspension, which has been thickened in a dewatering device, is subjected to an acid - base treatment for improving the process and/or the product. The invention provides improvements in the brightness of the pulp suspension and/or reduces the need for bleaching agent. The invention also decreases the dissolution of calcium carbonate filler in the process.
摘要:
A modified Family (11) xylanase enzyme comprising cysteine residues at positions (99) and (118) to form an intramolecular disulfide bond is provided. The modified xylanase is produced by substitution of an amino acid at position (99, 118) or both positions (99) and (118) with a cysteine to produce the intramolecular disulfide bond. Xylanases of the invention display improved thermophilicity, alkalophilicity or thermostability relative to wild-type xylanases. Such xylanases find use in a variety of applications in industry that require enzyme activities at temperatures and/or pH values above that of the native enzyme.
摘要:
Final chlorine dioxide bleaching of lignocellulosic materials is most effective at a near-neutral pH but present industrial practice typically targets a final pH of between 3.5 and 4.0 because of the difficulty in achieving and maintaining near-neutral pH cost effectively. The in situ formation of bicarbonate before the addition of chlorine dioxide provides a way of maintaining the required near-neutral pH. Near-neutral final chlorine dioxide bleaching also produces a bleached pulp that is in a state that responds more effectively to fluorescent whitening or optical brightening agents.