Abstract: A method is provided for treating pulp fibres, that have already been curled which method comprises: subjecting the pulp to a heat treatment while the pulp is at a high consistency, thereby to render the curl permanent to subsequent mechanical action. This permanent curl has advantages for papermachine runnability and for increasing the toughness of the finished product.

Abstract: Press dried paper sheets from certain ozonated high yield pulps are disclosed. Such sheets show substantially improved strength over comparable sheets prepared from non-ozonated pulps and over non-press dried sheets from ozonated pulps.

Abstract: Process for stabilizing solutions of peroxidic compounds used for bleaching. At least one polymer derived from an alpha-hydroxyacrylic acid, which contains units of the formula ##STR1## where R.sub.1 and R.sub.2 represent hydrogen or an alkyl group comprising from 1 to 3 carbon atoms which can be substituted by a hydroxyl group or a halogen atom, R.sub.1 and R.sub.2 being identical or different, and where M represents an alkali metal atom, a hydrogen atom or an ammonium group, is added to the solution as a stabilizer.

Abstract: An additive comprising an anionic organic surface active agent is incorporated into mechanical or thermomechanical pulp at an elevated temperature and pressure. The additive causes dispersion of lignin and retards redeposition of lignin so that the bursting strength of the paper formed from the pulp is improved. The preferred additives are higher molecular weight anionic organic polyelectrolytes or polymers, particularly polymeric sulfonates. Further improvement in bursting strength is achieved by the wet end addition of a cationic organic polyelectrolyte or polymer, with or without starch. Lower molecular weight anionic organic detergents can also be used but should be rinsed from the pulp before forming paper.

Abstract: A solution containing cellulose dissolved in a mixture of a tertiary amine N-oxide solvent for cellulose and a compound which increases the rate of dissolution of cellulose in the solvent such as a tertiary amine or other compound which increases the pH of the solvent, a process for making such a solution and a process for making shaped articles therefrom are provided. The solvent dissolves cellulose at a faster rate and at a lower temperature than a solvent consisting of the same tertiary amine N-oxide.

Abstract: A process is provided for preparing groundwood pulp from debarked pulpwood logs, which comprises grinding the logs in the presence of water under a superatmospheric pressure of a gas selected from the group consisting of steam, air, and steam and air, and forming and discharging a pulp suspension in the resulting aqueous liquor, while continuously supplying water during the grinding in a volume of less than 35 parts per part of bone dry pulp at a rate of addition such that the temperature of the discharged pulp suspension is below 200.degree. C. and preferably below 180.degree. C. and within the range from about 1.5 to about 50, preferably from 2 to 8, times the temperature in .degree.C. of the added water at a pressure within the range from about 8 to about 40 kiloponds/cm.sup.2, preferably from 10 to 30 kiloponds/cm.sup.2, higher than the superatmospheric pressure and at a temperature within the range from about 2 to about 63.degree. C.

Abstract: A process for making a refiner mechanical pulp from wood chips which comprises:(a) Comminuting the wood chips largely by splitting along the wood grain;(b) Wetting said particles with a solution of a sulphite salt of an alkali metal to add an amount of said alkali metal salt within the range of 1% to 10% of the oven dry weight of said particles, said solution having a pH within the range of 7 to 12.5;(c) Steam heating the sulphite salt solution bearing particles to a temperature within the range between 80.degree. C. and 165.degree. C. and holding them within that temperature range for a period of 0.5 to 80 minutes;(d) Passing the particles, after said period of heating, through a disc refiner to produce refiner mechanical pulp.

Abstract: Properties of mechanical paper pulp which is produced by grinding or otherwise frictionally acting on natural fibrous raw material containing plasticizable constituents which become heated to a temperature sufficiently high to soften the plasticizable constituents thereof are improved by the addition of paper filler material which is chemically inert to the pulp at a time which results in the filler being in contact therewith while the plasticizable constituents are plasticized and thus softened and sticky. This causes the filler, without chemical reaction, to adhere to the plasticized constituents and thus to the fibers of the pulp to result in improved properties of a totally mechanical pulp. The properties which are improved include the optical and printing properties of the paper made from the pulp.

Abstract: A process is provided for preparing groundwood pulp from debarked pulpwood logs which comprises grinding the logs under a superatmospheric pressure of a gas selected from the group consisting of steam, air and steam and air, while continuously supplying thereto process white water and water separated in thickening groundwood pulp suspension at a temperature within the range from about 75.degree. to about 100.degree. C.

Abstract: A process is provided for preparing groundwood pulp from debarked pulpwood logs, which comprises grinding the logs under a superatmospheric pressure of a gas selected from the group consisting of steam, air, and steam and air, while continuously supplying thereto water comprising spent bleaching liquor at a temperature of at least 70.degree. C. and forming a pulp suspension in the resulting aqueous liquor; centrifugally separating steam from the pulp suspension and using the separated hot steam to heat spent bleaching liquor supplied for the grinding; thickening the pulp suspension to a concentration within the range from about 5 to about 40% and supplying water separated therefrom to the grinding; diluting the pulp suspension to a concentration within the range from about 0.5 to about 4.

Abstract: A process is provided for the bleaching of cellulose pulp, particularly for the peroxide bleaching of high yield pulp, which comprises forming a suspension of lignocellulosic pulp material; mixing the suspension in a mixing zone with a bleaching agent while adjusting the temperature of the pulp suspension to within the range from about +10.degree. C. to about -10.degree. C. of a temperature within the range from about 40.degree. to about 95.degree. C. at which bleaching is to be carried out; quickly dewatering the pulp suspension to a pulp consistency within the range from about 18 to about 50%, equal to or at most 5% less than the pulp consistency of the pulp suspension charged to the mixing zone; passing the dewatered pulp suspension to the bleaching zone before its temperature can change substantially from the adjusted temperature; carrying out the bleaching with a bleaching agent at the selected bleaching temperature within the range from about 40 to about 95.degree. C.

Abstract: A high-strength, high-yield sulfite-modified thermomechanical pulp is formed by subjecting lignocellulose to multistage mechanical attrition, the first stage being conducted at elevated temperature and pressure and the second stage being run under atmospheric conditions. A sulfite chemical is added to the lignocellulose prior to the second stage, the lignocellulose being sulfonated so that a percent bound sulfur level of at least about 0.15% is provided. A novel linerboard composition is unexpectedly produced employing replacement quantities of the above described pulp.

Abstract: A process for producing high yield chemimechanical pulps from woody lignocellulosic material, such as wood chips, whereby the material is treated with an aqueous solution of a mixture of sulfite and bisulfite, said solution being of sufficient strength to sulfonate said material to at least about 85% of the maximum level of sulfonation that can be achieved on said material without reducing the pulp yield to below 90% and subjecting the resulting sulfonated material to mechanical defibration.

Abstract: The present invention relates to fluffed pulp comprising unwashed mechanical pulp with a liquid-diffusing capacity of at least 3.5 grams liquid per gram pulp per minute, a bulk of at least 18 cm.sup.3 /gram and a volume weight in blocks or bales of at most 0.8 grams/cm.sup.3. The invention also comprises a method of producing such a fluffed pulp by means of defibrating the wood and thereafter drying the same with warm air to a dry content of 80-95% by weight without subjecting the pulp to any mechanical compression.

Abstract: A composition which consists essentially of a mixture of oligomeric and polymeric oxidation products of cellulose, hemicellulose and lignin containing carboxy, ether and hydroxy groups as obtained by the direct oxidation of a woody plant material, preferably in an aqueous suspension thereof, using alkali hypohalite in a one stage oxidation procedure or nitrogen dioxide, alkali periodate or lead tetraacetate followed by alkali chlorite or alkali hypochlorite in a two stage oxidation procedure. The resulting oxidation products as obtained by one of these specific processes are especially valuable as additives to a surface active detergent or cleaning agent.

Abstract: A stream of disintegrated fibrous cellulosic pulp material and steam under pressure is subjected to an instantaneous pressure reduction as said stream and steam pass through a throttling nozzle, in a throttling zone, wherein a liquid solution of a bleaching agent is admixed with said stream and which stream, admixed with bleaching agent, is then passed into an expansion zone ahead of the throttling nozzle resulting in a uniform dispersion of the bleaching agent into the fibers in the stream of fibrous cellulosic pulp material.

Abstract: A process for the preparation of a cellulose pulp by mechanically freeing wood fibers in a grinder to form a fibrous pulp and bleaching the fibrous pulp with a peroxide-containing bleaching agent, as the only bleaching agent, in a peroxide bleaching stage, the mechanical freeing of the fibers being carried out in the presence of a spent liquor from the peroxide bleaching stage have a pH of 7 to 9.