Abstract: A process for reducing the energy requirements for drying a cellulosic pulp slurry by contacting a pulp slurry with sodium sulfate before web formation, dewatering and drying.

Abstract: An improved wood pulping process for the delignification of wood in a solvent wherein the solvent is a supercritical fluid under supercritical conditons and contains a delignification agent such as sodium hydroxide, sodium sulfide and/or sodium bisulfate.

Abstract: The present invention provides a process for bleaching and delignifying cellulose-containing products with peroxides and/or oxygen and/or ozone, wherein there is additionally used 0.01 to 2.5% by weight of cyanamide and/or cyanamide salts, referred to the dry weight of the cellulose.

Abstract: A cellulose pulp slurry is delignified in an apparatus comprising a vertical cylindrical barrel chamber, a cone-shaped bottom chamber connected to the barrel chamber and having a circular inlet formed in a lower end portion thereof, and a cone-shaped top chamber connected to the barrel chamber and having a circular outlet formed in a top end portion thereof, in which apparatus the cone-shaped top and bottom chambers converge at a convergence angle of 60 degrees or less respectively, by feeding a cellulose pulp slurry containing an alkali and oxygen and having a pulp consistency of 8 to 15% into the apparatus through the circular inlet of the bottom chamber at 70.degree. C. to 140.degree. C., and discharging the pulp slurry through the circular outlet of the top chamber, while controlling the flow speed of the pulp slurry in the barrel chamber to a level of 0.4 m/min or more.

Abstract: Method of reducing the energy consumption at the refining/beating of cellulose-containing material by the addition of alkali to the material for neutralizing acid groups bonded to the fibre wall. According to the invention, the pH-value in the pulp suspension is measured at the refiner outlet, the alkali is added in an amount depending on the measured pH value for neutralization without excess in the beating zone or immediately before the material enters the same, in an amount of 0.05-9 kg/ton, preferably 0.5-5 kg/ton, suitably 1-4 kg/ton, calculated as NaOH.

Abstract: An imitation leather product and a process for the preparation of the imitation leather product from natural hemp which comprises the steps of (a) firstly digesting natural hemp fiber with weak alkali solution, (b) secondly digesting with ammonia gas, (c) presoak treating either with methylol urea and ammonium phosphate, or sodium chromate and sulfuric acid, and immediately adding ammonia thereto, respectively, (d) beating with SBR resin and cyclohexylcarboxyl diphenylamino thiazolyl sulfonamide, (e) jetting through a multiple stage fiber jetting device, and soaking in a soaking bath container containing methylphenol and SBR resin.

Abstract: Pulp of improved refinability for the production of high strength linerboard is obtained by digesting wood chips in alkaline cooking liquor, defibering, treating with oxygen and alkali in the absence of a cellulose protector, and refining. Linerboard pulp produced by this method results in improved paper strength properties. The treatment is conducted in its best mode at temperatures below 100.degree. C. to minimize pulp yield losses.

Abstract: An improved process for delignifying and bleaching nonwoody, lignocellulosic material into products digestible by ruminants and ingestible by humans. The process comprises treating the substrate in an alkaline solution for a period of time, separating the wetted substrate from the slurry and then treating the wetted substrate with an alkaline peroxide solution at an initial pH of 8.5 to 11.0 for a period of time, and separating, washing and drying the product.

Abstract: The invention relates to a method and an equipment for preparing NaCMC, in which (a) cellulose is slushed in the reaction medium until a consistency of c. 5-15%, preferably 5-10%, (b) the fibre suspension obtained in step (a) is thickened to a consistency of c. 20-35% and (c) the pulp containing reaction medium obtained in the second step is homogenized by means of a screw conveyor having a screw pitch which decreases from an inlet opening thereof towards an outlet opening thereof, in order to increase the reactivity, whereby a mercerization activating the cellulose is carried out after step (b) and/or (c), and the cellulose thus pretreated is etherified in a manner known per se.

Abstract: The chemical components of lignocellulosic material that have been dissociated by a stream explosion process can be extracted from the mixture of components using a solvent extraction process. The dissociated lignocellulosic material is put in a column and the substances which are soluble in water, alcohol and caustic are leached out of the mixture by solvent extraction with relatively small volumes of those solvents. No agitation is used. Substantially pure cellulose remains in the column and it can be bleached before removal from the column.

Abstract: A process for the separation of the fibres from each other in lignocellulosic (straw, bagasse, wood) composites, and at the same time to dissociate the Lignin and the Xylan in the middle lamella and the primary wall of the lignocellulosic material, to enable a simple non reactive solvent extraction of the middle lamella and primary wall components while substantially retaining the structural integrity of the fibre bundle, sometimes referred to as the S2 layer, which is the strength member of the lignocellulosic fibre. The purpose of this process is to produce a fibre suitable to replace conventional Chemical Thermal Mechanical Pulp, for paper or as a carrier for high absorbency Cellulose in diaper and similar absorbent material applications, and at the same time to recover the chemical components of the middle lamella and the primary wall of the fibre, as co-products in a marketable, chemically reactive form.

Abstract: The present process produces a long fiber suitable for making various paper products. The long fiber is derived from Crotalaria juncea. The processing consists of a particular technique for preparing the fiber for digestion and a particular digestion sequence. In the preparation of the fiber for digestion it is dried to less than about 30 percent moisture, moist depithed, washed and wet depithed. The fiber is then processed at a high caustic concentration using a sequence of digestion-pressure reduction-digestion. Optionally there can be a third stage of digestion with a pressure reduction prior to the digestion. After digestion has been completed the fiber is refined and sent to blowdown. The fiber is then screened, washed and bleached. The resulting long fiber will product a high quality paper or is admixed with short fibers and various paper products can be made.

Abstract: A chemical pulping process is disclosed wherein wood chips are partially defiberized such that the fibers in the chips are substantially separated from one another but sufficient interfiber bonding is maintained to preserve chip integrity and thereby provide chips having an open porous fibrous network; and the chips are subjected to chemical pulping at an elevated temperature to remove a majority of the lignin in the chips.

Abstract: An improved process for delignifying and bleaching nonwoody, lignocellulosic material into products digestible by ruminants and ingestible by humans. The process comprises treating the substrate in an alkaline solution for a period of time and adding magnesium ions prior to adding peroxide or, alternatively, adding the magnesium to the peroxide prior to adding the peroxide to the alkaline slurry.

Abstract: Bamboo can be formed into a suitable pulp if prior to digestion it undergoes a process of shredding, washing and wet depithing. The fibers are then chemically digested preferably by a process which uses rapid pressure drops to open the fibers using the energy contained in the wet superheated fibers.

Abstract: A method of treating an aqueous sodium sulfide solution, such as white liquor in kraft pulping systems, for the oxidation of the sulfide with oxygen in the presence of a specific activated carbon catalyst which is (a) a particulate activated carbon catalyst having an average particle diameter of 0.2-4 mm, a pore volume of at least 0.25 cc/g in pores with diameters of not smaller than 100 .ANG. and a pore volume of at least 35% of the total pore volume in pores with diameters of not smaller than 100 .ANG. or (b) a fibrous activated carbon catalyst having a specific surface area of 300-2500 m.sup.2 /g and an outer surface area of 0.1-5 m.sup.2 /g.

Abstract: A process for the production of a pulp from bast fibers, which includes reacting a mixture of the bast fibers and an aqueous digestion liquid at a temperature of 60.degree.-130.degree. C. The digestion liquid includes (a) hydrogen peroxide or a compound capable of generating hydrogen peroxide in the presence of water, (b) an alkali metal carbonate, and (c) an oxalate.

Abstract: Lignocellulosic material, after delignification in an alkaline pulping liquor, can be removed from the digester in which it was pulped by first cooling the cooked material and relieving the overpressure from the digester, and then pumping the cooked material from the digester to a receiving vessel as a fluid suspension in spent liquor. When the fluid suspension is pumped at a low flow rate, the pulp thus obtained is superior in its physical properties to pulped material which is discharged under conventional conditions of high pressure and high flow rate from batch or continuous digesters.

Abstract: A process for bleaching a lignocellulosic matter in the form of a mechanical, thermomechanical, chemicomechanical or chemicothermomechanical papermaking pulp, or of wood chips while being converted into one of these pulp types by processing in a machine consisting essentially of two interpenetrating spiral surfaces wound around parallel shafts driven in synchronous rotation in the same direction inside a barrel which encloses them, and determining between upstream and downstream in the direction of forward travel of the matter a series of zones for drawing and braking the matter, which comprises combining a bleaching treatment using a reducing agent and a bleaching treatment using an oxidizing agent, characterized in that, after pretreatment using at least one metal-complexing or sequestering agent, the lignocellulosic matter undergoes a washing operation with an efficiency greater than 96% before undergoing in succession a bleaching treatment using a reducing agent at a pH of between about 8 and 12, a washin

Abstract: A process is disclosed for the pretreatment of lignocellulosic fibrous materials prior to delingification. The process in one of its embodiments is comprised of the following steps:1. Contacting the pulp material with treated filtrate and alkali for a short reaction period of about 1 to 2 minutes at 40.degree. C.,2. Withdrawing part of the liquid phase by filtration,3. Displacing substantially all of the remaining liquid phase with treated filtrate, and4. Allowing the pulp to react under conditions normally used for alkaline extraction or oxygen delignification.The treated filtrate is obtained by subjecting the liquor removed from the pulp at steps 2 and 3 to temperature of 5.degree. to 60.degree. C. for periods of about 5 to 10 minutes. Alternatively, step 3 can be eleminated.

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 process for preparing a cellulose paste by treatment of lignocellulose materials which comprises impregnating wood or vegetable shavings in divided form with an aqueous solution containing 2 to 20% by weight of alkaline metal hydroxides, alkali metal salts, or alkaline earth metal hydroxides, adjusting the weight of the solution retained by impregnation to a value representing 1 to 3 times the weight of treated material, the ratio of the weight of the impregnated mass to the dry weight of the lignocellulosic material being preferably not more than about 2.6:1, subjecting the impregnated masses to cooking treatment by exclusively indirect heating at a temperature varying from 150.degree. to 200.degree. C. without exerting any mechanical disintegrating action for a period varying from 15 to 60 minutes, and pressing the cooked product so as to extract therefrom the solubilized lignin in the form of a black liquor containing about 50% of dry material.

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: Sulfite pulp having increased tear, Scott bond, and stretch properties and above about 90% dirt reduction without bleaching. Methods for making such sulfite pulp by increasing the consistency of conventional sulfite pulp to above about 12 percent, shearing the increased consistency pulp under compressive forces to improve the tear and stretch properties of the pulp, refining the sheared pulp at pressures above atmospheric to remove dirt particles and achieve a desired freeness level, and removing fiber knots from the refined 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: A process for the delignification of cellulosic materials, wherein a high-yield cellulose pulp and high-value by-product, such as reactive lignins of low molecular weight are produced, which comprises degassing lignocellulosic material, rapidly heating the lignocellulosic material in a liquor comprising water, an organic solvent and a buffer thereby maintaining a substantially neutral solvent extraction, such that said lignocellulosic material is cooked in the liquor as it is heated from a temperature of 150.degree. C. to a selected maximum temperature in the range of 200.degree. to 280.degree. C.; and rapidly cooling the mixture to a temperature less than 150.degree. C. The reaction is controlled to maximize reactive lignin solvation while suppressing cellulose degradation.

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 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 process of treating fibrous ligno-cellulose material to form defibered chemical cellulose pulp suitable, for example, for the manufacture of paper and paperboard and dissolving pulp and to treat defibered ligno-cellulose material to produce basic animal feed or packaging and building boards.The process is based on the nitration and dissolving of the lignin component of the cellulose material either in an alkaline solution or with a two step operation in which the nitration can be in an acid stage comprising the step of submerging the fiberous ligno-cellulosic material in aqueous nitric acid having an HNO.sub.3 concentration in the range of about 0.125 to 9 weight percent, followed by an alkaline stage to dissolve out the nitrated lignin from the fibrous structure. In the production of chemical pulp or animal feed the lignin containing solution (black liquor) is separated from the cellulose material.

Abstract: High strength and high density wood fiberboard is formed by treating the wood fiber source material with a highly alkaline solution, such as sodium hydroxide solution, before interfelting the fibers into a loose mat. The wood source material may be treated after refining the material into fibers, but preferably, the wood source material is treated before fibrillation. Further, wood fiber source material may be partially neutralized before felting without substantial change in the resulting densities and strengths.

Abstract: This invention concerns a treatment for preserving or protecting moist wood against attacks from microorganisms (fungi) with the use of evaporable or sublimable ammonium salts. The protection is obtained by distributing the salts close to the wood so that the salts form an atmosphere around the wood in which the microorganisms cannot develop. The treatment is of special interest for moist wood during a storage period until it has been dried and is not further attached by fungi.

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: A two-stage process is provided for the conversion of lignocellulosic material, for instance, wood, to cellulose pulp, first oxidizing the lignocellulosic material to form aldonic acid end groups, preferably bound with 1,4-glycosidic bonds, in the polysaccharides, in an alkaline medium in the presence of the oxidized form of a redox additive which is converted into a reduced form in reaction with the wood and/or products formed from the wood, withdrawing the alkaline medium and then reoxidizing the reduced form of the redox additive in the absence of the lignocellulosic material at a rate to maintain the oxidized form of the redox additive in a major proportion in the alkaline medium during oxidation of the lignocellulosic material by contacting the withdrawn alkaline medium with oxygen-containing gas, and then continuing the digestion in an alkaline medium at a temperature within the range from about 160.degree. to about 200.degree. C.

Abstract: An improved pulping process for producing high yield pulps from woody lignocellulosic material wherein the lignocellulosic material is treated with a pulping chemical and mechanically defibrated. The improvement comprises pre-treating the lignocellulosic material by impregnating same with a loweralkanolamine so as to cause softening of lignin in the material and to promote fiber separation. As a result, pulping chemical and refining energy consumption as well as vapor and liquid effluent pollution are significantly reduced.

Abstract: A nonsulfur chemimechanical pulping process for producing pulp from woody materials is disclosed. The process is particularly suited for producing corrugating medium pulp from hardwood chips although the process can be adapted to production of other types of pulp and can use other types of woody materials. The process comprises impregnation and dilution of the chips in a dilute aqueous pulping solution of a lower alkanolamine catalyzed with ammonium hydroxide. The preferred alkanolamine is monoethanolamine present in a weight ratio to ammonium hydroxide of about 1 part to 1 part or less to 1 part to 3 parts or more. The pulping solution may be repeatedly reused and the process of this invention does not produce environmentally objectionable by-products.

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: This invention relates generally to the extraction process and provides a novel process and reactor for the continuous extraction of vegetable-fibre material such as wood chips. The process comprises a two stage process, the first stage comprising an extraction process using a methanol:water mixture and the second stage using the same extraction liquid as the first with a greater proportion of water, with sodium hydroxide and anthraquinone. A part of the extraction liquid which is saturated by extraction substances is continually carried away at each stage and after extraction, the mixture is subjected to washing. This process has eliminated the heavy pollution produced by the prior art processes and also has reduced the cost and complexity of the prior art processes.

Abstract: Process for cooking lignocellulosic materials by heating the said materials in a cooking solution containing caustic soda with or without an alkali metal sulphide, in which the solution used contains about 0.01% to 10%, preferably 0.05% to 2%, by weight of 1,2,3,4-tetrahydro-9,10-anthracenediol based on the weight of the dry lignocellulosic material.

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 method for produce both kraft pulp and alcohol from hardwood chips or the like. The chips are subjected to mild acid prehydrolysis following by mild caustic pre-extraction. The withdrawn hydrolysate has insufficient furfural to inhibit microorganism growth, and both the hexose and pentose sugars in the hydrolysate are fermented to ultimately produce ethanol, butanol, or the like. The chips - after caustic pre-extraction - are subjected to a sulphate cook, and wash, and the resultant pulp is kraft pulp and even has viscosity and tear strength characteristics more desirable than that of conventional kraft pulp. The pulp can be subjected to oxygen delignification, and achieve a higher K number in fewer subsequent bleaching stages than conventional kraft pulp.

Abstract: An improvement in a method for producing paper is disclosed. The paper-producing method involves the steps of preparing a slurry of high lignin content having a predetermined freeness and containing from 1 to 20 percent by weight of fibers, refining the slurry to enable the production therefrom of paper having predetermined properties, forming a web from the slurry and drying the web. The improvement involves treating the high lignin content slurry, prior to the refining step, with a sodium, potassium or lithium alkaline sulfite/sulfide/carbonate solution at atmospheric pressure at a temperature of at least 60.degree. C. and at a pH of at least 10 for from 10 to 60 minutes. The amount of the sulfite/sulfide/carbonate solution should be sufficient that the treatment increases the strength of paper made at the same degree of freeness. The slurry should be one in which at least 50 percent of the fibers are softwood fibers and containing not more than 3.0 percent of residual cooking chemicals.

Abstract: A process for producing a highly qualified dissolving pulp sheet is disclosed, wherein the pulp sheet exhibits reduced swelling tendencies and improved mercerizing properties, combined with at least reduced need for dialysis of the mercerization liquor in any subsequent viscose processing, while reducing the energy consumption in the treatment process. A substantial proportion of the hemicellulose in a pre-hydrolyzed bleached sulfate cellulosic pulp is removed by contacting the pulp with an aqueous solution of sodium hydroxide. The pulp is subjected to mechanical working under a net energy supply of 15-100 KWh/ton pulp to split the primary layer, and at least the outer parts of the secondary layer, of the pulp fibers substantially without fibrillation. The pulp can be washed, dried and pressed to form sheets.The dissolving pulp produced by this process is suitable for the production of reinforcing cord, such as tire cords and the like.

Abstract: A process for delignifying lignocellulosic material with a digestion liquor of nitroanthraquinones and/or dinitroanthraquinones. The process can be carried out in a closed reaction vessel at temperatures of 150.degree.-200.degree..+-. C. for 0.5 to 480 minutes with 0.001 to 10% nitroanthraquinone and/or dinitroanthraquinone by weight of lignocellulosic material.

Abstract: In a two-stage cellulosic pulping and bleaching system having first-stage pulping using standard pulping chemicals and second-stage bleaching using an alkaline oxygen system, the addition of a protector occurs only in the first stage pulping instead of between the first and second stages or in the second stage bleach. A magnesium compound is normally used as the protector.

Abstract: A method of producing peroxide bleached pulp. Lignocellulose fiber material is impregnated with an aqueous silicate solution containing a sequestering agent. The impregnated lignocellulose is preheated with saturated steam at a temperature corresponding to the defibrating temperature to precipitate silic acid on and in the fibers. The preheated fiber mass is defibrated between two grinding disc in an atmosphere of saturated steam at a temperature of 100.degree.-170.degree. C. Alkaline peroxide solution free of silicate is introduced into the grinding space.

Abstract: Lignocellulose is treated with an alkaline pretreatment liquor containing anthraquinone or other pretreatment agent in a continuous process in which the lignocellulose and pretreatment liquor flow countercurrently. The pretreatment agent is substantially soluble in the pretreatment liquor introduced into the pretreatment zone and is substantially insoluble in the pretreatment liquor withdrawn from the pretreatment zone, with the result that the pretreatment agent is effectively recycled within the pretreatment zone.

Abstract: A nontoxic cellulose solvent and process for forming and utilizing the same. The solvent includes a metal chelating agent, a metal compound, an oxygen scavenging stabilizing agent and a caustic swelling agent with the disclosed solvent being prepared in either aqueous or solid form. The solvent is caused to contact cellulosic materials in order to dissolve cellulose therefrom. The dissolved cellulose may be reprecipitated and may then be hydrolyzed by cellulose enzyme or acid to yield glucose with lignin being removed either before or after hydrolysis has occurred.

Abstract: Paper pulp is produced by a process in which raw sugar mill bagasse is moist depithed, wet bulk stored in the presence of an inorganic and organic preservative, wet depithed by hydraulic shearing in the presence of an inorganic color remover, pulped, washed, cleaned and dewatered.

Abstract: A process for the delignification of .Iadd.softwood .Iaddend.lignocellulosic material is described wherein the lignocellulosic material is cooked with .[.an alkaline or.]. .Iadd.a .Iaddend.neutral sulphite pulping liquor, and there is added to the pulping liquor at least 0.001% by weight of an additive compound or mixture of additive compounds selected from quinones and hydroquinones.

Abstract: An improved process for the production of pulp from lignocellulosic material characterized by the employment of a cooking aid is disclosed. The cooking of the lignocellulosic material is carried out in the presence of a small amount of a compound selected from the group consisting of hydroxyanthracenes and derivatives thereof.