Weyerhaeuser Company Limited

North Pacific Paper Corporation

North American Paper Corporation

Roger O Campbell

Michael A Veal

Jerry R Speaks

Anthony Parrish

Robert T Hamilton

Paul B Mobley

Gregg McCarthy

Zeecha L Brooks

Raymond E Harrison

Kaaren K Haynes

Methods of bleaching mechanical pulp under alkaline conditions with hydrogen peroxide. The methods include introducing a source of magnesium ions and hydroxyl ions to a refiner. The wood particulates are refined into a pulp in the presence of the magnesium ions and hydroxyl ions, and optionally perhydroxyl ions to simultaneously refine and bleach the pulp in a refiner.

Refiner bleaching with magnesium oxide and hydrogen peroxide

A method of making bleached mechanical pulps is disclosed for pulping mills having a primary and a secondary refiner. A first step is to provide cellulosic materials, such as wood chips to refine into the pulp; the wood chips have an initial brightness level. A second step is to provide a bleaching liquor to the refining system of the pulp mill, wherein the liquor comprises an amount of hydrogen peroxide and an amount of alkali having greater than 0% to 100% magnesium hydroxide or soda ash or a combination thereof. A third step is to hold the pulp with the bleaching liquor at a temperature in the range of about 85&deg; to about 160&deg; C. and for about 2 to about 180 minutes. The components of the bleach liquor can be added at the first refiner or interstage between refiners.

High temperature peroxide bleaching of mechanical pulps

A process for producing paper and absorbent products of increased strength includes extracting wood particulates with a solvent selected from methanol, ethanol, and acetone at a pressure less than 50 psi to reduce the pitch and volatile organic compounds of the particulates without significant dissolution of lignin and cellulosic components. The wood particulates are pulped to produce a pulp with reduced pitch content. A slurry is prepared from the pulp and used to form paper products.

Process for producing paper and absorbent products of increased strength

A chemical wood pulping process having reduced volatile organic compound emissions includes extracting wood particulates with solvent at a pressure less than 50 psi to reduce naturally-occurring particulate pitch and volatile organic compound content without significant dissolution of lignin and wood cellulosic components. The solvent used is methanol, ethanol, or acetone. This is followed by comingling the extracted wood particulates with a liquor having chemical reactants, not including the solvent used to extract the wood particulates, for solubilizing lignin. Then, allowing the chemical reactants of the liquor to react with lignin contained in the extracted wood particulates under controlled conditions of temperature and pressure for a sufficient time to solubilize and remove lignin. This is followed by producing a wood pulp having individual cellulosic fibers while releasing a reduced amount of VOCs in the wood pulping process.

Chemical wood pulping process with reduced pitch and VOC emissions

Paper and absorbent products having reduced pitch content and enhanced properties, including increased tensile index, tear index, burst index, Scott Bond, smoothness, and stiffness. Further, pulps of the invention, although having slightly reduced brightness, are more responsive to bleach chemicals thereby permitting the use of less chemicals to achieve a specific brightness. The products are produced by a process that includes extracting wood particulates with a solvent for naturally-occurring volatile organic compounds and pitch. The extracted wood particulates are then pulped and formed into paper and absorbent products with enhanced properties. Due to the extraction of volatile organic compounds, the pulping and paperforming stages of the process are substantially free of emissions of volatile organic compounds that occur naturally in wood. Moreover, the extraction of pitch reduces or eliminates pitch fouling of equipment and permits the production of paper products of enhanced qualities.

Process for producing a wood pulp having reduced pitch content and process and reduced VOC-emissions

Wood products of superior strength are produced from wood particulates that have been extracted with a solvent to remove volatile organic compounds and a significant proportion of pitch from the wood particulates. The products are especially resistant to weakening caused by water immersion. As a consequence of the enhanced strength and stiffness of the composites, wood products may be made thinner, and of lighter weight, for the same equivalent strength and stiffness at lower cost. The process of drying the particulate raw material and forming the composite wood products, by subjecting to heat and pressure, are virtually free from emissions of volatile organic compounds into the environment.

Composite wood products prepared from solvent extracted wood particulates

A process for extracting volatile organic compounds and pitch from wood particulates, thereby virtually eliminating the emission of volatile organic compounds into the atmosphere during the processing of wood particulates into commercially useful products, such as oriented strandboard, particle board, chipboard veneers, and pulp and paper products. The removal of pitch permits the production of pulps of higher brightness, requiring less chemical bleaching agents. Moreover, removal of pitch eliminates pitch scale formation in pulp mills and on pulp and paper machines with resultant improved efficiencies and reduced use of pitch treatment chemicals. In the extraction process, a solvent or blend of solvents, leach wood extractives, including volatile organic compounds and pitch, from the wood particulates to produce a miscella. The miscella is separated from the leached wood particulates and solvent contained in the miscella is recovered and recycled for reuse. The wood extractives of the miscella may be sold as chemical feedstocks or used as a fuel. Any volatile organic compounds released as vapors in wood processing operations prior to the extraction step are collected, absorbed onto activated carbon particulates, and recovered for sale or combustion.

Pretreatment of wood particulates for removal of wood extractives

Wood products of superior strength are produced from wood particulates that have been extracted with a solvent to remove volatile organic compounds and a significant proportion of pitch from the wood particulates. The products are especially resistant to weakening caused by water immersion. As a consequence of the enhanced strength and stiffness of the composites, wood products may be made tier, and of lighter weight, for the same equivalent strength and stiffness at lower cost. The processes of drying the particulate raw material and forming the composite wood products, by subjecting to heat and pressure, are virtually free from emissions of volatile organic compounds into the environment.

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Federal Way, WA, United States of America

Roger O Campbell