Abstract: Deinking of impact and nonimpact printed paper is accomplished by repulping the printed paper in an alkali aqueous medium containing a deinking composition comprising one or more nonionic surfactants and/or alkanols. The presence of the deinking composition causes ink particles to agglomerate, which are removed from the aqueous medium by size and density separation. The invention provides an agglomeration method with high ink removal from all types of impact and nonimpact printed paper.

Abstract: An improved process for delignification of lignocellulosic raw material, such as wood chips, for the production of cellulose pulps for use in the manufacture of paper or paperboard and an improved pulping aid composition for use in said process are disclosed wherein the wood chips are treated in a closed reaction vessel with an alkaline pulping liquor with an amount of a cyclic keto compound, such as anthraquinone, included therein for achievement of a determined pulp yield, wherein the improvement comprises a reduction in the amount of anthraquinone required to achieve said yield by the addition to said alkaline pulping liquor, in addition to a reduced amount of the anthraquinone, a surfactant mixture comprising at least one alkyl alcohol alkoxylate and at least one polyoxyalkylene glycol ether of an ester of an acid selected from the group consisting of ricinoleic acid and 12-hydroxystearic acid.

Abstract: An improved process for delignification of lignocellulosic raw material, such as wood chips, for the production of cellulose pulps for use in the manufacture of paper or paperboard and an improved pulping aid composition for use in said process are disclosed wherein the wood chips are treated in a closed reaction vessel with an alkaline pulping liquor with an amount of a cyclic keto compound, such as anthraquinone, included therein for achievement of a determined pulp yield, wherein the improvement comprises a reduction in the amount of anthraquinone required to achieve said yield by the addition to said alkaline pulping liquor, in addition to a reduced amount of the anthraquinone, a surfactant mixture comprising at least one alkyl alcohol alkoxylate and at least one polyoxyalkylene glycol ether of an ester of an acid selected from the group consisting of ricinoleic acid and 12-hydroxystearic acid.

Abstract: A process for delignifying and bleaching lignocellulose-containing pulp, in which the pulp is delignified with a peracid or a salt thereof, treated with a complexing agent, and subsequently bleached with a chlorine-free bleaching agent. Suitably delignification is carried out with the strongly oxidizing peracetic acid, giving a considerable increase in brightness and a considerable reduction of the kappa number after bleaching with a chlorine-free bleaching agent comprising at least one of a peroxide-containing compound, ozone or sodium dithionite, or optional sequences or mixtures thereof. The brightness increasing effect is highly selective, i.e. the viscosity of the pulp is maintained to a comparatively great extent. Both the delignification and the treatment with a complexing agent are advantageously carried out at a close to neutral pH, thus minimizing the need of pH adjustment and making it possible to use spent bleach liquor internally, e.g. for washing the pulp.

Abstract: This invention relates to an environmentally preferred process for the delignification of a cellulosic biomass comprising pulp. The process uses the oxidative properties of nascent oxygen to complete pulping and bleaching operations. The process may be used in a pulping stage, a bleaching stage or can be used for both the pulping and bleaching stages of a delignification process. The process does not rely on large volumes of environmentally offensive chemicals such as caustic soda, sulfur, and chlorine to achieve delignification of the pulp.

Abstract: An elementally chlorine-free method for the delignification and bleaching of pulp which involves the use of a neutral monoperoxysulfate bleaching step to delignify and thus brighten the pulp. The process achieves good selectivities above about 3 even at high delignification degrees of 60% or greater.

Abstract: Crosslinked cellulose fibers having free pendant carboxylic acid groups are disclosed. The fibers include a polycarboxylic acid covalently coupled to the fibers, and are crosslinked with a crosslinking agent having a cure temperature lower than the cure temperature of the polycarboxylic acid. Methods for producing the fibers and for producing a fibrous sheet incorporating the fibers are also disclosed.

Abstract: A process for the preparation of a stable water-in-oil emulsion of a hydrolyzed polymer of an N-vinyl amide of the formula ##STR1## in which R and R.sup.1 denote H or C.sub.1 -C.sub.6 alkyl, by the polymerization of a compound of the formula I alone or in admixture with another ethylenically unsaturated monomer in the presence of a polymerization initiator and emulsifier in the form of a water-in-oil emulsion, to form a water-in-oil polymeric emulsion, followed by hydrolysis of the polymer in the form of the water-in-oil polymeric emulsion in the presence of an acid or base and from 1 to 30 wt %, based on the polymer, of an emulsifier, the emulsifier used being a mixture of(a) from 5 to 95 wt % of a block or graft copolymer of the structure (A-B)m, (A)-B or (B)-A, in which in each case(a) from 5 to 95 wt % of a block or graft copolymer of the structure (A-B).sub.m, (A).sub.n B or (B).sub.

Abstract: The invention relates to the use of dialdehydes and acetals thereof for inhibiting decomposition of peroxide in the production and the treatment of recycled fiber pulp and other fiber pulp.

Abstract: A process for bleaching a chemical paper pulp, including, in the order recited, subjecting the chemical paper pulp to treatment with oxygen in a preliminary delignification stage which does not employ chlorine in an acidic medium or a combination of chlorine and chlorine dioxide in an acidic medium; subjecting the chemical paper pulp to treatment with peroxymonosulphuric acid in a peroxymonosulphuric acid stage carried out at a temperature ranging between 75.degree. and 100.degree. C. for a period ranging between 70 and 150 minutes and at a pulp consistency of ranging between 12 and 25% of dry matter; and subjecting the chemical paper pulp to treatment with alkaline hydrogen peroxide in an alkaline hydrogen peroxide stage.

Abstract: A process for treating a substrate, e.g., lignocellulosic pulp or cellulosic pulps, with a mixed peracid solution comprising percarboxylic acid and Caro's acid which results in a higher conversion rate of the active oxygen in the hydrogen peroxide in order to provide an inexpensive and effective delignification and/or bleaching solution and the process for making the mixed peracid solution.

Abstract: A process for delignification and bleaching of chemically digested lignocellulose-containing pulp, where the pulp is treated with a complexing agent at a pH between 3.1 and 9.0, whereupon the pulp is bleached with ozone. The initial treatment with a complexing agent removes the ions of certain metals detrimental to the subsequent ozone bleaching, while retaining in the pulp the desirable ions, primarily of alkaline earth metals. Thereby, the selectivity in the delignification is increased and the strength of the pulp maintained. The pulp can be bleached with peroxide before the ozone step and/or after the treatment according to the invention, to obtain the desired final brightness and completely avoid formation and discharge of chlorinated organic compounds.

Abstract: Pulp bleaching processes employing peroxides and/or oxygen are improved by using bleaching additives, preferably before the application of the peroxide and/or oxygen. The bleaching additives contain at least one alkali metal sulfamate such as a sodium sulfamate and a polyaminocarboxylic acid such as DTPA or a salt thereof, such as sodium DTPA.

Abstract: Process for bleaching a chemical paper pulp by means of a sequence of treatment stages involving at least one stage with an enzyme and at least one stage with a peroxyacid.

Abstract: A process for the bleaching of pulp comprising the step of bleaching the pulp with hydrogen peroxide and an effective amount of at least one biodegradable 1-aminoalkane-1,1-diphosphonate chelating agent to enhance the bleaching of the pulp, is disclosed. Also disclosed is the use of a 1-aminoalkane-1,1-diphosphonate to enhance the bleaching of pulp with hydrogen peroxide, as well as the pretreatment of pulp with a 1-aminoalkane-1,1-diphosphonate prior to the step of bleaching with hydrogen peroxide. Finally, the deinking of pulp in the presence of 1-aminoalkane-1,1-diphosphonate is also disclosed.

Abstract: Pulp bleaching processes employing peroxides and/or oxygen are improved by using stabilizing bleaching additives, preferably before the application of the peroxide and/or oxygen. The bleaching additives contain at least one sulfamic acid or sulfamate such as sodium sulfamate and gluconic acid or a soluble gluconate, or alternatively an alkali metal borate.

Abstract: A process of de-inking waste paper can be operated under conditions using a simple combination of chemicals to result in a waste liquor that is substantially environmentally friendly. The process comprises forming a pulp from the waste paper in a aqueous medium that has a pH of between 6 and 9 and that is substantially free of dissolved phosphate and that includes an ink-dispersing amount of polycarboxylic acid dispersing agent, and separating the ink from the pulp. The use of a cationic surfactant for promoting flotation is particularly desirable.

Abstract: A method for controlling foam in the papermaking operation comprising a polyether surfactant and polyethoxylated sorbitol hexaoleate.

Abstract: A process for deinking recycled paper using a pressurized deinking module to separate ink from paper pulp stock. The addition of salts of imidazolinium based compounds with alkyl, alkenyl and amidoethyl side chains to the pulp slurry at the beginning of the pressurized deinking module cycle removes ink more effectively and results in a brighter recycled paper and an increase in yield of final paper stock.

Abstract: A process of delignifying and bleaching a chemical wood pulp with hydrogen peroxide and dicyandiamide as an activator provides a higher degree of delignification and brightness of the pulp and overcomes problems of fiber degradation. The process comprises adding hydrogen peroxide and dicyandiamide as a bleaching activator to a chemical wood pulp slurry under alkaline conditions.

Abstract: A process for the production of cellulose from wood and annual plants is provided where the digesting liquor contains free caustic soda, sodium salts of alkyl benzenesulfonic acids, and of aromatic or aliphatic carboxylic acids. By the addition of anthraquinone or its derivatives to the digesting liquor, the delignification is improved. Anthraquinone is resistant to wet oxidation and can be reintroduced into the digesting process. The solubility and, therefore, the effectiveness of anthraquinone is improved by the use of sulfonic acid salts. For the recovery of the digesting chemicals contained in the black liquor, solubilized liquor is precipitated with mineral acid or carbon dioxide and the hemicelluloses are separated by ultra filtration. The resins are separated by extraction with the residual organic compounds, except for the sulfonates and carboxylics, being burned in an aqueous phase with air and/or oxygen.

Abstract: A method of manufacturing chemical pulp out of comminuted cellulosic fiber material comprising digesting the fiber material with digestion liquid without preceding peroxide stage. According to the invention the comminuted fiber material is treated in at least one stage prior to said digestion, in the presence of a liquid containing at least one compound having the ability to form complexes with metals existing naturally in the fiber material.

Abstract: A process for treating a substrate, e.g., lignocellulosic pulp or cellulosic pulps with a mixed peracid solution comprising percarboxylic acid and Caro's acid which results in a higher conversion rate of the active oxygen in the hydrogen peroxide in order to provide an inexpensive and effective delignification and/or bleaching solution and the process for making the mixed peracid solution.

Abstract: A method for conditioning the felts in a papermaking process utilizing deinked secondary fiber in the furnish by adding a felt conditioner consisting of from 5-33% of a nonionic surfactant, from 5-33% of a dispersant, or blends thereof, with the remainder water; wherein the nonionic surfactant is selected from the group consisting of ethoxylated nonylphenols having moles of ethoxylation of from 7.5 to 30 and an HLB of about 12 to 17.2 and di-alkyl phenol ethoxylates having moles of ethoxylation of from 15 to 24 and an HLB of about 13 to 15.1; and wherein the dispersant is selected from the group consisting of the sodium salt of naphthalene sulfonate formaldehyde-condensate having an average molecular weight of from about 700 to 3500, the potassium salt of polymerized alkyl naphthalene sulfonic acid having an average molecular weight of approximately 1000, or the sodium or ammonium salt of lignosulfonate. Additionally, from 1 to 5% of an alkylether hydroxypropyl sultaine enhances performance.

Abstract: Process for high pH metal ion chelation in pulps. Extraction and removal of detrimental metal ions and organic solvent extractives prior to delignification and bleaching is carried out on pulp, preferably kraft pulp, at a pH over 5, more preferably a pH over 6, most preferably a pH of 7-9. Aqueous pulp is first brought to a pH of about 3-6 to cause chelation and desorption of metal ions from the fiber phase of the aqueous pulp, and at the same time implementing air entrainment and evaporation. The pH is then raised, and the extractable species are removed by dewatering and washing the pulp.

Abstract: A process for chlorine-free bleaching of chemical pulp in association with the production thereof, where a suspension of the pulp preferably has a concentration exceeding 8% of cellulose-containing fiber material and where the pulp entering into a bleaching line is preferably fed continuously through at least one bleaching vessel in the bleaching line, is treated with at least one acid for adjusting the pH to a value below 7, and with a chelating agent, and is subsequently bleached in at least one stage to a brightness exceeding 75% ISO, preferably exceeding 80%, with hydrogen peroxide or the corresponding quantity of another peroxide, employed in a quantity exceeding 5 kg/BDMT, where the peroxide bleaching takes place at elevated temperature and at a pressure in the bleaching vessel which exceeds 2 bar and where the cross-sectional area of the bleaching vessel exceeds 3 m.sup.2 and the area of the metal surface exposed towards the interior of the bleaching vessel is less than 4 V m.sup.

Abstract: Paper pulp, especially recycled paper pulp which has been deinked, is bleached in a synergistic two-stage process first with sodium bisulfite and then with sodium borohydride. The borohydride is preferably added in an aqueous mixture with sodium hydroxide. A weak acid such as acetic acid may be added to the pulp to advance further the brightness gain.

Abstract: Process for improving the selectivity of the delignification of a chemical paper pulp by employing a peroxyacid, in which the unbleached pulp originating from the cooking operation is treated with an aqueous solution of this organic peroxyacid in the presence of at least one stabilizer selected from phosphonic acids and their salts.

Abstract: Process for preserving the mechanical strength properties of a chemical paper pulp, comprising two treatment stages by means of a peroxidic reagent, with the first stage in an acidic medium and the second stage in an alkaline medium, according to which a treatment by means of a reducing compound is interposed between the two stages.

Abstract: Disclosed is a method for the delignification of lignocellulosic materials with acidic solutions of peroxymonophosphoric acid for the delignification and brightening of cellulosic pulps in bleaching; for the production of cellulosic pulps for use in paper making and in regenerated cellulose products; for enhancing the properties of recycled cellulosic fibers and for use in animal feeds and other products where removal or degradation of lignin is beneficial.

Abstract: In manufacturing fiberboard, it is known to press mixtures of lignocellulosic material and binding agents to form a board product. In this invention, an improved process for manufacturing fiberboard is disclosed including the step of adding a solution of maleic anhydride and glycerol to the lignocellulosic material prior to refining thereof. The binder used is preferably phenolic-formaldehyde resin, in which case post-heating may be beneficial.

Abstract: A process for cooking wood to pulp by contacting the wood with a deresinating agent containing fatty acid esters of polyoxyalkene glycols priors to cooking the wood with an alkaline liquor to simultaneously reduce pulp rejects and increase pulp yield.

Abstract: The present invention relates to the addition of photosensitising compounds to woodpulps and mixtures thereof for enhancing their whiteness, brightness and chromaticity, as well as to the paper making fibres so obtained and the use thereof.

Abstract: A process for the delignification of cellulose fiber plant raw material for the production of pulp using separate impregnating and delignifying stages, each using alcohol and alkali. The process may be carried out in batch or in a continuous process. Less alcohol is used in the delignification stage than in the delignification stage. The pulp produced has very good properties because different amounts of alcohol are being used in the impregnation stage and in the delignification stage.

Abstract: A method for enhancing pulp washing efficiency is disclosed. An anionic sulfonate surfactant is added within the washing or pulping operation to enhance the removal of lignin and spent cooking chemicals from pulp.

Abstract: A process for bleaching pulp, in which, after fiber liberation, a first filtrate containing metals, principally in ionic form, is separated off from the pulp, and supplied downstream to the pulp flow after a bleaching stage.

Abstract: Process for the delignification of a chemical paper pulp by means of an organic peroxy acid, according to which the raw pulp arising from the cooking operation is treated with an aqueous solution of this organic peroxy acid, whose hydrogen peroxide content does not exceed 20% of the weight of the peroxy acid.

Abstract: Polyglycerol esters have been found to be effective antifoam agents in aqueous systems employed in paper processing. Adjunct antifoam agents are not required. Best results are obtained with polyglycerol esters having a degree of glycerine polymerization in the range of 3 to 6 and an esterification range of 15 to 85%.

Abstract: A process for delignifying a lignocellulosic material comprising exposing the material to a mixture of peracid and ozone. Preferred peracids include Caro's acid and peracetic acid. Also disclosed is a kraft pulp delignification mixture comprising in combination: (a) water; (b) a kraft pulp at 1-40% consistency; (c) a peracid; and (d) from 0.1 to 5.0% ozone on pulp.

Abstract: A scale deposit inhibitor and a method for continuously controlling scale deposition applicable to a digester and its peripheral equipment used in kraft pulp manufacture are disclosed, the scale deposit inhibitor comprising a maleic acid-acrylic acid-hypophosphorous acid terpolymer having a maleic acid unit to acrylic acid unit molar ratio of 1:4 to 4:1, a hypophosphorous acid unit content of 1 to 12 mol %, and a weight average molecular weight of 500 to 10000. The scale deposit inhibitor is added to a cooking liquor in a concentration of 0.01 to 10 ppm per ppm of a calcium ion in the cooking liquor.

Abstract: Transition metals are removed from cellulose pulp and treatment fluids in a pulp mill. Medium consistency digested pulp is treated in an acidic stage, and then washed to produce a filtrate. The pH of at least a substantial part of the filtrate is adjusted so that it is greater than 9 (preferably greater than 10.5), while a sufficient carbonate content is provided to keep the calcium content low. Adjusting the pH causes dissolved transition metals in the filtrate to precipitate as solids, and the solids can then be filtered out, e.g. by precoat filtering, or clarification followed by polishing filtering. The greatly reduced transition metal content filtrate is then used elsewhere in the pulp mill, as in a washer following an oxygen delignification stage. The acidic stage may be an EDTA stage, an ozone stage, an acid only stage, etc., and the pulp is preferably treated so that it is bleached in at least one Z stage and one P stage, and preferably also an E (e.g. E.sub.op) stage.

Abstract: A method for delignification and bleaching of cellulosic pulp which comprises reacting a cellulosic pulp with peracetic acid, ozone and oxygen under conditions of acidic pH. The ozone substantially completely reacts with the pulp and, thereafter, the oxygen reacts with the pulp under under an acidic pH.

Abstract: In a three-stage process for the delignification of cellulose-containing raw materials, pulping is initially performed with a solution of concentrated aqueous acetic acid at an elevated temperature and under an elevated pressure. The resultant acetic acid-moist pulp is treated in a second stage with the aforementioned pulping solution with the addition of nitric acid and is then washed or extracted with water or with the pulping solution. In a third treatment stage, the thus-obtained acetic acid-moist pulp is treated with an ozone-containing gas.

Abstract: A chemical pulp which contains reactants capable of generating dioxirane within the pulp is produced in a process which comprises mixing a pulp with reactants comprising a carbonyl compound, preferably acetone, and an oxygen donor, preferably monoperoxysulfate, in proportions which produce a water-soluble dioxirane having a molecular diameter of less than 140 angstrom units. Such a pulp bleaching process which employs dioxirane as a bleaching agent is rendered environmentally and economically acceptable by recycling the reactants employed to produce the dioxirane.

Abstract: A method of bleaching a chemical pulp by adjusting the pH of the pulp to 1.5-3.5, chelating the pulp and then treating the pulp in an N stage with nitric oxide (NO) in the amount of at least 1.5% by weight of the oven dried pulp at a consistency of between 30 and 55% and further treating the pulp in a Z stage with ozone to produce a bleach pulp having a higher viscosity for a given permanganate number compared with a similar pulp bleached without using the N stage.

Abstract: Hydrolyzed copolymers (A) maleic anhydride with (B) at least one more ethylenically unsaturated monomer other than acrylic acid or methacrylic acid or with a mixture of (B) and (C) acrylic acid or methacrylic acid are employed in a process to inhibit calcium oxalate formation and deposition.

Abstract: The invention relates to a process for bleaching chemically delignified lignocellulose-containing pulp, to render more efficient a peroxide-containing treatment stage, by treating the pulp with a complexing agent before the peroxide step, so that the trace metal profile of the pulp is altered by the treatment with the complexing agent, in the absence of sulphite, at a pH in the range from 3.1 up to 9.0 and at a temperature in the range from 10.degree. C. up to 100.degree. C., whereupon, in a subsequent step, the treatment with a peroxide-containing substance is carried out at a pH in the range from 7 up to 13, said two-step treatment being carried out at an optional position in the bleaching sequence applied to the pulp.

Abstract: Brown stock washing of wood pulp is improved by adding a water-soluble cationic polymer to the wash water. The cationic polymer reacts with lignin solution present in the larger channels in the pulp mat to give a precipitate which lowers the flow rate of wash water through the larger channels. A more efficient wash water usage is obtained.

Abstract: A process for the continuous mass-production of chemical pulp from cellulose raw materials without adversely affecting the environment involves digesting the cellulose raw materials at 130.degree. to 200.degree. C. with a cooking liquor containing an alkali, hydrogen peroxide, a chelating agent, an anthraquinone and water. A pulp waste liquor and unbleached pulp are obtained by subjecting the digested cellulose raw materials to solid-liquid separation. The pulp waste liquor is concentrated and burned to obtain an alkali metal carbonate. Calcium oxide is added, if necessary, to the aqueous solution of sodium or/and potassium carbonate for causticization, and hydrogen peroxide, a chelating agent, and an anthraquinone are added to the alkali solution to regenerate the cooking liquor.

Abstract: A novel composition for use in a process for cooking wood to form pulp and processes for using same are provided. The composition and variations thereof are useful in enhancing the uniformity of wood cooking and reducing the rejects in a pulping process for the production of pulp. The composition comprises esters of block copolymers having the general formula ##STR1## wherein x, y, and z each have a value of at least one.