Abstract: A multistage process for bleaching high-yield and ultra high-yield pulps is described whereby the pulp is treated sequentially with a peroxygen compound, a reducing compound and a final peroxygen compound to achieve higher brightness levels.

Abstract: This invention relates to an improved process for preparing pulp suitable for paper making. Although processes using explosive decompression have been known in the past, it has been believed that these must be conducted at relatively low temperatures. Although such known processes of explosive decompression resulted in a saving of power, the physical strength was low, the color was relatively dark and there was a considerable yield loss. This invention is to provide a process to achieve the saving of power resulting from the use of explosive decompression but in which there is good brightness, high yield and good fiber strength. The process of this invention defines conditions for achieving these objectives. These conditions include impregnation of the chips of other wood fragments under specified conditions and cooking with saturated steam at a high temperature and pressure followed by explosive decompression and refining.

Abstract: A process for peroxide bleaching of mechanical pulps by washing the pulp to remove substantially all of the heavy metal ions from the pulp, mixing hydrogen peroxide in an amount of at least about 11/2% based on the dry weight of the pulp with the washed pulp to uniformly disperse the hydrogen peroxide throughout the pulp followed by mixing an aqueous solution of sodium hydroxide with the pulp containing hydrogen peroxide to uniformly distribute the sodium hydroxide throughout the pulp and to react the sodium hydroxide with the peroxide to produce perhydroxyl ions in situ in the pulp and then reacting the perhydroxyl ions with the pulp to increase the brightness of the pulp and provide a residual peroxide of at least 35% of the peroxide added. This system provides a significant increase in residual brightening chemical in the residual liquor separated from the brightened pulp.

Abstract: A lignocellulosic raw material is pulped with a cooking liquor containing organic peroxyacids, such as peroxyformic acid or peroxyacetic acid, and the defibered pulp is bleached with an alkaline solution containing hydrogen peroxide, the pH of which is at least 10 in the beginning of the treatment, and which is provided by adding to a sodium hydroxide solution, hydrogen peroxide in an amount which if calculated as a percent of the dry weight of the material coming to the treatment corresponds to from 0.20 to 0.80, preferably from 0.25 to 0.70 and most preferably from 0.45 to 0.65 times the kappa number of the pulp obtained from the previous stage of the process.

Abstract: A process of preparing new chemical paper pulps wherein a first cooking stage is effected in the presence of sodium hydroxide and advantageously adjuvants, after which an intermediate grinding is effected and followed by a second cooking stage characterized in that the second cooking stage is performed in the presence of a peroxide alkaline solution containing a peroxide stabilizing agent.

Abstract: A method is disclosed to degrade lignin comprising reacting the lignin in a liquid medium under aerobic conditions with an amount of persulfate anion and a transition metal cation effective to catalyze the oxidative degradation of the lignin.

Abstract: A method of producing salts of monoperoxysulfuric acid comprising reacting together, in the presence of a catalyst consisting of cupric ions in a concentration of at least 0.01 part per milion, (a) a solution of aerated water having a pH of from about 8 to about 14, and (b) a sulfur-containing reactant, wherein said reactant comprises sulfur dioxide or a sulfite. If a pulp is added to the reaction mixture and the cupric ion concentration is increased, the monoperoxysulfuric acid salts that are genrated in situ in the reaction mixture will simultaneously bleach the pulp.

Abstract: In accordance with the invention a chemimechanical pulp is produced from lignocellulosic material, for example wood chips, by subjecting the material to a process in which it is steamed, impregnated with alkali and peroxide, drained, pre-heated, refined and bleached. The material is impregnated in a single stage with a solution containing alkali and peroxide. Subsequent to passing an intermediate drainage and reaction stage, the material is pre-heated to a temperature of from about 50.degree. C., but not above 100.degree. C. The material is then refined in one or two stages. The material can be impregnated by immersing the same in the impregnating solution for a period of up to 20 minutes at a temperature of 15.degree.-60.degree. C., or by compressing the material in a screw press and permitting the compressed material to expand in the impregnating solution.

Abstract: Mechanical pulp is bleached by a treatment with hydrogen peroxide wherein prior to or simultaneously with said treatment the mechanical pulp is subject to an oxygen pressure.

Abstract: A process for the oxidative or reductive bleaching of wood pulp, especially in the presence of heavy metal salts, in which a complex former combination containing at least one phosphonic acid, at least one polyhydroxycarboxylic acid and at least one phosphate or salts thereof is added to a wood pulp slurry in an amount of from 0.5 to 50%, based on the dry mass of the wood pulp, and subsequent bleaching is carried out in the presence of a reducing agent. Also provided is a complex former combination for use in the oxidative or reductive bleaching of wood pulp, comprising at least one phosphonic acid, at least one polyhydroxycarboxylic acid and at least one phosphate or salts thereof.

Abstract: A two-stage hydrogen peroxide bleaching treatment of chemical pulp at a temperature of about 90.degree.-100.degree. C. comprising subjecting said pulp in a first stage to hydrogen peroxide and to at least about 3 grams/1 of bath of a metal ion sequestering agent selected from nitrogen containing sequestering agents or agents derived from polyphosphoric or polyphosphonic acids at a pH of 8.5 to 9.5 so that hydrogen peroxide of about 0.3 to 2.5 wt. % relative to dry pulp weight is consumed, and subjecting said pulp in a second stage to hydrogen peroxide and to at least about 3.times.10.sup.-3 gram-atoms per 100 grams of dry pulp of magnesium in the form of magnesium hydroxide and a pH of at least about 11 so that about 2 to 5 weight % of hydrogen peroxide per weight of dry pulp is consumed during the two stages.

Abstract: A method of peroxide bleaching lignocellulose-containing material for providing a pulp of both high strength and brightness. Increase in strength is provided in a first stage by hyper-alkaline peroxide bleaching known per se, i.e. bleaching carried out at an initial pH of over 12, measured in the bleaching liquid at 24.degree. C. before mixing into the pulp. The desired brightness increase is provided in a subsequent stage with or without intermediate washing of the pulp and at a lower initial pH.

Abstract: Bleaching of wood pulp is improved by the combination of a pretreatment of the pulp with a polyaminocarboxylic acid, e.g. ethylenediaminetetraacetic acid, prior to bleaching with an alkaline aqueous peroxide solution containing a stabilizing amount of an aminophosphonic acid derivative together with a polymer of an unsaturated carboxylic acid or amide or an alkylsulfonic acid substituted amide.

Abstract: A process of preparing a bleaching liquor with an improved stability involves mixing of magnesium ions and hydrogen peroxide prior to the addition of sodium hydroxide. The liquor may be used to bleach Kraft wood pulps, obtaining higher brightness levels.

Abstract: A method and apparatus provide for the bleaching of mechanical pulp in such a way that the brightness of the mechanical pulp can be increased up to about 7-10 points. Mechanical pulp directly from a secondary refiner is separated, as by first and second centrifugal separators (cyclones), into a fines fraction and a fiber fraction. The fines fraction is under about 200 mesh. The fiber fraction is mixed with hydrogen peroxide (H.sub.2 O.sub.2) and subjected to displacement bleaching, which uses a minimum about of bleaching chemical to obtain the maximum brightness. The fines fraction is mixed with hydrogen peroxide and subjected to non-displacement bleaching. The fines fraction is between about 10-20 percent of the total feed pulp stream. After bleaching, the fines and fiber streams can be recombined before passage to a paper products production machines.

Abstract: The extent of delignification of chemical pulps by oxygen-containing chemicals, preferably hydrogen peroxide, is enhanced by demethylating the pulp prior to such oxidative delignification, to a degree of demethylation of at least about 30%, preferably at least about 50%. Demethylation may be achieved by chemical treatment of the already-formed pulp or by modification to the pulping process to result in demethylated pulp.

Abstract: A two-stage pulp refining system in which the fibrous material from the first stage refiner is in contact with an alkaline bleaching solution between refining stages at a temperature of 32.degree.-96.degree. C. and at a consistency of 15-25% on an oven dry basis. The material is then diluted and then pressed to a consistency of at least 20% and passes through the second stage refiner.

Abstract: The brightness of a thermomechanical pulp can be improved if a serial multiple blowdown technique is used and a bleachant is present at an effective concentration throughout the thermomechanical pulping process.

Abstract: A method is disclosed for achieving additional bleaching of a wood pulp following a peroxide bleaching of the pulp, the method involving added thiourea to the slurry at a pH of 4 to 7 in the presence of residual peroxide and thereafter maintaining the slurry at a pH of 8 to 11.

Abstract: Delignification and bleaching of lignocellulosic material is obtained with catalyzed hydrogen peroxide in alkaline medium.

Abstract: By treating agricultural crop residues and other nonwoody lignocellulosic plant substrates with H.sub.2 O.sub.2 at a controlled pH within the range of about 11.2 to 11.8, the substrates are partially delignified and unprecedented levels of the cellulose and hemicellulose as insoluble fractions are made available for subsequent use. The products of this treatment are nontoxic and are characterized by low crystallinity and near quantitative cellulase digestibility. They are useful as carbohydrate sources in ruminant feeds and as microbial feedstocks for commercial process such as the production of alcohol and generation of single-cell protein.

Abstract: A process for the delignification and bleaching of cellulose with oxygen and hydrogen peroxide, in which in a given case the delignification is carried out with oxygen in the presence of MgO, and the cellulose subsequently is bleached simultaneously with hydrogen peroxide and oxygen at a pH<5.

Abstract: A pollution free pulping process wherein a lignocellulosic material is subjected to various pulping and bleaching steps without the use of sulphur and chlorine. The system is a closed one thus minimizing energy and chemical requirements while permitting one to obtain a product having excellent physical properties.

Abstract: An aqueous composition containing hydrogen peroxide, or a precursor which will form said peroxide in aqueous solution, is inhibited from decomposition in the presence of small amounts of copper, iron, manganese or other transition metal ions and in the presence of significant amounts of alkaline earth metal ions, e.g. Ca or Mg, by the presence of a combination of inhibitors one being from the group consisting of alkyleneaminephosphonic acids and the other being from the group consisting of polyalkylenepolycarboxylic acids and their analogous amides and sulfonic acid derivatives.

Abstract: A process is provided for pretreating particulate lignocellulosic material to remove heavy metals and resin without any delignification or defibration, which comprises washing particulate lignocellulosic material; compressing the washed material to a solids content of at least 40% to remove absorbed and excess liquid; impregnating the compressed material with an alkaline aqueous solution comprising alkali and at least one of a heavy metal ion complexing agent and a heavy metal ion reducing agent; heating the impregnated material at a temperature within the range from abut 50.degree. to 100.degree. C. for up to approximately 0.75 hour; compressing the pretreated material to a solids content of at least 40%; and separating undiluted liquor squeezed out during the compression, while maintaining conditions during the pretreating such that the pH of the squeezed-out liquor is within the range from about 4 to about 9.

Abstract: A multi-stage process for the delignification and bleaching of lignocellulosic pulp is disclosed wherein the first alkaline extraction stage comprises extracting the pulp with caustic in the presence of oxygen and either a hypochlorite or a peroxide.

Abstract: Wood pulps, particularly sulphonate pulps, such as jack pine ultra-high-yield pulps produced by sulphonation, are readily discolored by metal ions commonly found in paper mills. Additions of 0.001 to 2% on pulp dry basis of tin ions, especially derived from stannous compounds, to wood pulps effectively brighten the pulps at ambient temperature.Metal ions such as ferrous, ferric, cupric, aluminum, nickel and manganese are common discoloring ions and pulps containing these ions can be brightened by the addition of tin ions particularly derived from stannous chloride, stannous sulphate, stannous tartrate, stannous oxolate, stannic chloride and stannic sulphate, the tin ions as Sn.sup.+2 being added in an amount to provide a ratio of stannous ions to discoloring metal ions up to about 2:1, preferably about 1.5:1.

Abstract: Waste paper containing polymeric contaminants is broken down in the presence of an acidic aqueous solution containing at least one peracid.

Abstract: The invention is a fibrous, cationic cellulose pulp product and the method for preparing it. A water suspension of cellulosic fiber is treated under alkaline conditions with a condensate of epichlorohydrin and dimethylamine. Up to 30 molar percent of the DMA may be replaced by a crosslinking agent such as ammonia or a lower aliphatic diamine. The process may be carried out at room or elevated temperatures. It is practical to add the condensate at one of the later alkaline stages of a bleaching process; e.g., an alkaline extraction or peroxide stage. This is most preferably done later than any chlorination or hypochlorite stages. The product shows greatly improved retention of acid and other anionic dyes. It also shows superior retention of some pigments and latices without the need for other cationic aids. In some cases a small amount of alum appears to have a synergistic retention effect with the cationic pulp product when used with titanium dioxide and certain anionic latices.

Abstract: The novel, advantageous, and economical process of reclaiming printed waste paper comprises subjecting waste paper to a flotation de-inking process. The degree of whiteness of the reclaimed paper is considerably increased by the addition of specific phosphonic acid compounds to the de-inking bath. Hydroxy carboxylic acids, amino carboxylic acids, polycarboxylic acids as well as magnesium sulfate may also be added to the de-inking bath containing the phosphonic acids.

Abstract: Treatment of lignocellulosic materials with monoperoxysulfate to permit more ready separation of non-cellulosic materials therefrom to produce papermaking pulps is disclosed.

Abstract: The invention relates to a process for the delignification of unbleached chemical pulp, comprising the following stages:(a) oxidation of the unbleached pulp with a peroxide, in an alkaline medium with a % ratio of peroxide/pulp with respect to the Kappa index of said pulp which may vary between 0.01 and 0.1 and a pH kept at between 9 and 12, the said oxidation stage being followed by(b) mechanical pressing of the oxidized pulp, with recycling of the extraction effluents from the pressing stage,partly above the oxidation stage,partly below the oxidation stage, with a view to ensure the prior dilution of the pulp oxidized before the pressing,and if necessary partly towards the wash of the unbleached pulp.Advantages: A reduction in the quantities of reagents to be used, a saving of heat energy and a reduction of the pollution.

Abstract: A process for the delignification and bleaching of chemical and semi-chemical cellulosic pulps in which the pulp is subjected to a treatment with oxygen and a subsequent treatment with peroxide. The effluent from the treatment with peroxide is at least partially recycled to the treatment with oxygen.

Abstract: Defiberized lignocellulosic material, such as wood, is treated with a liquid carrier containing an oxidizing agent (a per compound, a chlorate or a nitrate), and the wet mat thereof is subjected to pressure, and to heat for a sufficient period of time to cause an oxidative reaction among the fibers resulting in a strong interfiber bond. Where the oxidizing agent is a per compound, the pH of the mixture or lignocellulosic material and per compound is less than 7. Catalysts or other reaction modifying agents are employed if needed. By virtue of the enhanced interfiber bonding effect, paper sheets, such as liner board, which are usually formed of delignified cellulosic material, the fibers of which are highly refined, can be formed totally or partially of less expensive sources of material such as ground wood, semi-chemical or semi-mechanical lignocellulosic pulps without sacrifice of strength.

Abstract: In a method for bleaching oxygen delignified cellulose-containing pulp such as sulphate, sodium and sulphite pulps with ozone and peroxide, the ozone treatment takes place at two stages, the alkaline solution which is added subsequent to the ozone treatment includes peroxide and complex formers, and 55 to 85% of the total amount of chemicals is added at the first stage.

Abstract: A process and apparatus are provided for the deresination and brightness improvement of cellulose pulp, by adjusting the pulp concentration to within the range from about 15 to about 35%; adding sufficient alkali to the pulp to bring the amount of alkali, calculated as NaOH, within the range from about 0.5 to about 17 g/kg of water accompanying the pulp; adding sufficient oxidizing bleaching agent to the pulp to bring the amount of oxidizing bleaching agent to within the range from about 0.2 to about 22 g/kg of water; subjecting the pulp to a mild, mechanical working in the bite of twin interdigitated rotating screws at an energy input of from 8 to 100 kWh per ton of pulp; removing and reacting the pulp with the added alkali and bleaching agent for from about 0.1 to about 5 hours; and then washing out dissolved resin from the pulp.

Abstract: A process for producing photographic paper comprising bleaching a paper web containing from 0 to 65% by weight water is disclosed.

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: A process and solution for delignifying and brightening lignocellulosic pulp. The solution comprises from about 0.1 to about 5% by weight, based on oven-dried pulp of a peroxide and about 0.5 to about 20 mole percent, based on the moles of peroxide, of a metal ion selected from the group consisting of tungsten, molybdenum, chromium, osmium and selenium. The preferred process of this invention comprises contacting a lignocellulosic pulp with about 0.5 to about 20 mole percent, based on moles of peroxide, of a metal ion selected from the group consisting of tungsten, molybdenum, chromium, osmium and selenium at a temperature below about 50.degree. C.; adjusting the pH of the resultant pulp slurry to between about 1 and about 7; adding 0.1 to about 5% by weight based on oven-dried pulp of peroxide and effecting pulp delignification and brightening at about 30.degree. C. to about 100.degree. C. until most of the peroxide has been consumed.

Abstract: An improved peroxide based brightening and delignifying solution and process for liqnocellulosic pulp, characterized by selective delignification and pulp viscosity retention is disclosed. The process comprises maintaining a pulp slurry to a temperature between 40.degree. C. and 120.degree. C. for 0.5 hours to 8 hours. The slurry comprises lignocellulosic pulp; from 0.1% to 20% by weight based on O.D. pulp of peroxide; from 0.1% to 10% by weight based on O.D. pulp of a metal-containing additive whose metallic portion is selected from the group consisting of tin, titanium, and vanadium; and sufficient acid to maintain the .sub.f H of the slurry between about 1 and about 7. In a preferred embodiment of this invention, a tin additive is employed and the partially delignified and brightened pulp is further bleached with the unconsumed peroxide by adjusting the pH of the slurry to between 8 and 12 and maintaining the temperature of the slurry from 40.degree. C. to 90.degree. C. for 0.1 to 4 hours.

Abstract: Treatment of lignocellulosic materials and bleaching of wood pulp with monoperoxysulfate to permit more ready separation of non-cellulosic materials therefrom to produce papermaking and bleached pulps.

Abstract: In the bleaching of wood pulp using the conventional CEH sequence with subsequent oxidation stages, the third stage (H) is replaced by peroxide oxidation (P) to a brightness level of 35-50 GE. Final brightness levels of 70-88 GE are attained using no greater amounts of chemicals in the subsequent stages than are required in the conventional CEHDH process. The temperature in the P stage is between 120.degree. and 170.degree. F.

Abstract: Cellulose is bleached by means of an organic peracid in the acid region and subsequently by means of peroxide in the alkaline region. As peracid there is employed an acid which is produced from the corresponding carboxylic acid by reaction with hydrogen peroxide in the presence of a mineral acid. The peroxide bleaching step which follows the peracid bleaching step is carried out after there is added the necessary amount of aqueous alkali solution for carrying out the peroxide bleaching step of the pulp without intermediate washing of the cellulose. A further addition of peroxide is not carried out.

Abstract: A chlorine-free bleaching process for lignocellulosic pulp characterized by a series of bleaching stages comprising in sequence a peroxide bleaching stage, the peroxide being selected from the group consisting of alkaline hydrogen peroxide, acidic hydrogen peroxide, and peroxy acid and at least one ozone bleaching stage and in one embodiment the sequence including an initial oxygen bleaching stage before the peroxide bleaching stage. In continuous operation the effluent from each of these sequential stages provides the preferred wash for the preceding washing step and the diluent for the preceding bleaching stage, the final effluent being recyclable for effective closed cycle operation.

Abstract: Process for inhibiting the corrosion of equipment made of titanium or of alloys containing titanium by a solution containing a peroxy compound. To effect the inhibition, a solution containing calcium, strontium or barium ions is used.

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: A silver halides photographic material with improved keeping quality, said material having a substrate formed by coating a base web with a film-forming resin, preferably a polyolefin resin, said base web being composed principally of natural pulp or a mixture of two or more different types of natural pulp having a post color number of 2 or below, said post color number being defined by the following formula: ##EQU1## [wherein Ro is brightness (%).times.(1)/(100) before fading treatment, R is brightness (%).times.(1)/(100) after 18-hour fading treatment at 85.degree. C. and 95% RH, and P is post color (PC) number which indicates the degree (nondimensional number) of fading].

Abstract: A process for the reclamation of waste paper in the presence of an aqueous alkaline solution comprises having the solution contain at least a carboxylated polymer.

Abstract: Described is a method of bleaching textile fabrics with potassium based bleaching liquors: One liquor is an aqueous solution of commercially available potassium orthosilicate, water and hydrogen peroxide and the other is an aqueous solution of water, hydrogen peroxide, and the reaction products of sodium silicate and potassium hydroxide (potassium orthosilicate and sodium hydroxide) the relative concentrations of the reactants being such that there are four moles of potassium hydroxide for every one mole of sodium silicate. In the latter liquor, the potassium ion concentration is always greater than the sodium ion concentration.

Abstract: An improvement upon processes for the bleaching of wood pulp which comprise preparing an aqueous alkaline bleaching medium containing hydrogen peroxide and contacting the pulp with said medium under agitation. The improvement particularly comprises agitating a suspension of the pulp in an aqueous medium containing the hydrogen peroxide and between about 15 and 65 percent by mol of one or more of a limited class of alkenylsuccinic anhydride compounds which are found to promote the bleaching of the wood pulp by the hydrogen peroxide. The improved process of the invention is further found to be necessarily restricted to operation under limited conditions of bleaching mixture temperature and pH.The invention is usefully applied in the preparation of a wide variety of paper and paperboard products. The invention has particular benefit in accomplishing a high degree of bleaching performance at relatively low bleaching system temperatures.