Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/10—Bleaching ; Apparatus therefor
  • D21C9/16—Bleaching ; Apparatus therefor with per compounds
  • D21C9/163—Bleaching ; Apparatus therefor with per compounds with peroxides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
  • B01J20/26—Synthetic macromolecular compounds
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/001—Modification of pulp properties
  • D21C9/002—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives
  • D21C9/005—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives organic compounds
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/38—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing crosslinkable groups

Definitions

• This disclosure relates to polyacrylic acid crosslinked cellulose fibers, and in particular to reduction of furfural, and accompanying malodor, that is generated during the curing stage of the crosslinking process.
• Cellulosic fibers are a basic component of absorbent products such as diapers. These fibers form a liquid absorbent structure, a key element of the absorbent product.
• Cellulosic fluff pulp a form of cellulosic fibers, is a suitable fiber for this application because a high void volume, or high bulk, liquid absorbent fiber structure is provided. This structure, however, tends to collapse during wetting, and this reduction in fiber structure bulk reduces the volume of liquid that can be retained in the wetted structure, and also inhibits the wicking of liquid into the unwetted portion of the cellulose fiber structure. Consequently, the potential capacity of the dry high bulk fiber structure is not realized and it is the fiber structure's wet bulk that determines the liquid holding capacity of the overall fiber structure.
• Fiber structures formed from crosslinked cellulosic fibers generally have enhanced wet bulk compared to those formed from uncrosslinked fibers.
• the enhanced bulk is a consequence of the stiffness, twist, and curl imparted to the fibers as a result of crosslinking. Accordingly, crosslinked fibers are advantageously incorporated into absorbent products to enhance their wet bulk.
• Polycarboxylic acids have been used to crosslink cellulosic fibers.
• absorbent structures containing individualized cellulosic fibers crosslinked with a C2-C9 polycarboxylic acid are described in U.S. Pat. No. 5,137,537, U.S. Pat. No. 5,183,707, and U.S. Pat. No. 5,190,563, among others.
• Absorbent structures made from these individualized, crosslinked fibers exhibit increased dry and wet resilience, and improved responsiveness to wetting, relative to structures containing uncrosslinked fibers.
• citric acid a monomeric polycarboxylic acid, is available in large quantities at relatively low prices making it commercially competitive with formaldehyde and formaldehyde-addition products, or urea-glyoxal condensation products.
• cellulosic fibers crosslinked with monomeric polycarboxylic acids tend to lose their crosslinks over time and revert to an uncrosslinked state.
• monomeric polycarboxylic acids such as citric acid
• citric acid crosslinked fibers show a considerable loss of crosslinks on storage.
• Such a reversion of crosslinking generally defeats the purpose of fiber crosslinking, which is to increase the fiber's bulk and capacity.
• the useful shelf-life of fibers crosslinked with these monomeric polycarboxylic acids is relatively short and renders the fibers somewhat limited in their utility.
• polymeric polycarboxylic acid crosslinked fibers exhibit a density that remains substantially unchanged over the lifetime of fibrous webs prepared from these fibers.
• This resistance to aging or reversion of density relates to the stable intrafiber crosslinks formed using such polymeric crosslinking agents.
• Cellulose fibers crosslinked with citric acid show a considerable increase in density, accompanied by a loss of bulk and absorbent capacity over time.
• the increase in density indicates a decrease in the level of crosslinking (i.e. reversion) in the fibers.
• the loss of crosslinking in the fibrous web results in a less bulky web and, consequently, diminished absorbent capacity and liquid acquisition capability.
• Some crosslinking agents can cause discoloration, i.e. yellowing, of the white cellulosic fibers at the elevated temperatures required to effect the crosslinking reaction.
• a possible mechanism, at least for citric acid, is a dehydration reaction resulting in aconitic acid and a yellow coloration attributable to the C ⁇ C chromophore.
• Bleaching for example, is a common method for increasing pulp brightness (as defined by the Technical Association of the Pulp & Paper Industry (“TAPPI”) or the International Organization for Standardization (“ISO”)).
• TAPPI Technical Association of the Pulp & Paper Industry
• ISO International Organization for Standardization
• Traditional bleaching agents include elemental chlorine, chlorine dioxide, and hypochlorites.
• bleaching, especially with chlorine-containing agents can be environmentally harsh, expensive, and a source of manufacturing bottleneck. Accordingly, there have been many attempts to reduce the number, nature, and quantity of bleaching agents used in bleaching methods.
• industry practice is to perform hydrogen peroxide bleaching in alkaline systems, such as by adding an alkaline agent (such as sodium hydroxide) in coordination with hydrogen peroxide in the bleaching stage.
• alkaline agent such as sodium hydroxide
• the '740 patent theorizes that the malodor is due to the collective presence of a host of substances including volatile phenolics, hydrogen sulfide, various sugar decomposition products (such as furfural, methyl furfural, and guaiacols), and citric acid anhydrides, and that the odor reduction may be due to the possible reduction of such substances by the combination of alkaline and oxidizing agents at a pH of at least 5.5.
• the present disclosure provides embodiments of polyacrylic acid crosslinked cellulosic fibers subsequently treated with hydrogen peroxide in the absence of sodium hydroxide, wherein the amount of furfural in the treated polyacrylic acid crosslinked fibers reduces from a first value determined at least one day after treatment of the polyacrylic acid crosslinked fibers to a second, subsequent value determined up to 21 days after treatment.
• the present disclosure provides embodiments of polyacrylic acid crosslinked cellulosic fibers having less than about 1.3 ppm furfural, for example by having been subsequently treated with hydrogen peroxide in the absence of alkaline or other bleaching agents.
• the present disclosure provides embodiments of polyacrylic acid crosslinked cellulosic fibers subsequently treated with hydrogen peroxide in the absence of alkaline of other bleaching agents, wherein the amount of furfural in the treated crosslinked fibers is reduced by at least 55% as compared with untreated polyacrylic acid crosslinked cellulosic fibers (that is, the same polyacrylic acid crosslinked cellulosic fibers except not given the aforementioned subsequent treatment).
• the present disclosure provides methods of reducing the malodor associated with the presence of furfural in polyacrylic acid crosslinked fibers that include applying hydrogen peroxide in the absence of other bleaching agents to the crosslinked fibers subsequent to curing the crosslinked fibers.
• the present disclosure provides methods of reducing the furfural content of polyacrylic acid crosslinked fibers, the method comprising applying hydrogen peroxide alone to polyacrylic acid crosslinked fibers, wherein the amount of furfural in the polyacrylic acid crosslinked fibers treated with hydrogen peroxide alone reduces from a first value determined at least one day after the treatment of the polyacrylic acid crosslinked fibers with hydrogen peroxide to a second, subsequent value determined up to 21 days after treatment with hydrogen peroxide.
• references throughout this disclosure to “an embodiment” or “one embodiment,” and so forth, indicates that a particular feature, step, technique, method, or other characteristic described in connection with the embodiment is included in at least one embodiment. However, references to “an embodiment” or “one embodiment” are not necessarily all referring to the same embodiment. Further, the particular features, steps, techniques, methods, and other characteristics may be combined in any suitable manner in one or more embodiments.
• furfural in cellulose fibers crosslinked with polymeric polycarboxylic acids is reduced by treatment of the fibers subsequent to crosslinking with hydrogen peroxide.
• the extent of furfural reduction is increased when hydrogen peroxide is used in the absence of sodium hydroxide or other alkaline agents relative to the extent of furfural reduction in the presence of such agents.
• a reduction in furfural levels is accompanied by a strong reduction of the malodor associated with the fibers. Accordingly, it is theorized that furfural is the main odoriferous volatile organic compound causing the malodor, and that treatment with hydrogen peroxide replaces the compound with reaction products that impart a clean, fresh odor.
• Hemicellulose which accompanies the cellulose fibers obtained from wood during the pulping process, is considered the main source for furfural generation during thermal treatment (e.g., curing) of the cellulose fibers, according to the following proposed mechanism.
• the present disclosure provides embodiments of polyacrylic acid crosslinked cellulosic fibers subsequently treated with hydrogen peroxide, wherein the amount of furfural in the treated polyacrylic acid crosslinked fibers reduces from a first value determined at least one day after treatment of the polyacrylic acid crosslinked fibers to a second, subsequent value determined up to 21 days after treatment.
• the bleached polyacrylic acid crosslinked fibers discussed herein are made from polyacrylic acid crosslinked cellulosic fibers. These crosslinked cellulosic fibers are obtained by treating cellulosic fibers with an amount of a polyacrylic acid crosslinking agent to provide intrafiber crosslinked cellulosic fibers having increased bulk.
• Polyacrylic acid crosslinked cellulosic fibers and methods for making polyacrylic acid crosslinked cellulosic fibers are described in U.S. Pat. No. 5,549,791, U.S. Pat. No. 5,998,511, U.S. Pat. No. 6,306,251, for example, and bleached polyacrylic acid crosslinked cellulosic fibers are described in U.S. Pat. No. 7,513,973.
• Polyacrylic acid crosslinked cellulosic fibers can be prepared by applying polyacrylic acid to the cellulosic fibers in an amount sufficient to achieve intrafiber crosslinking.
• the amount applied to the cellulosic fibers can be from about 1 to about 10 percent by weight based on the total weight of fibers.
• crosslinking agent in and amount from about 4 to about 6 percent by weight based on the total weight of dry fibers is applied.
• Polyacrylic acid crosslinked cellulosic fibers can be prepared using a crosslinking catalyst.
• Suitable catalysts can include acidic salts, ammonium sulfate, and alkali metal salts of phosphorous-containing acids.
• the crosslinking catalyst is sodium hypophosphite.
• the amount of catalyst used can vary from about 0.1 to about 5 percent by weight, based on the total weight of dry fibers.
• cellulosic fibers useful for making the bleached polyacrylic acid crosslinked cellulosic fibers in accordance with the present disclosure are derived primarily from wood pulp.
• Suitable wood pulp fibers for use with the invention can be obtained from well-known chemical processes such as the kraft and sulfite processes, with or without subsequent bleaching.
• the pulp fibers may also be processed by thermomechanical, chemithermomechanical methods, or combinations thereof.
• the pulp fiber is produced by chemical methods, although ground wood fibers, recycled or secondary wood pulp fibers, and bleached or unbleached wood pulp fibers can be used.
• a suitable starting material is prepared from long-fiber coniferous wood species, such as Southern pine, Douglas fir, spruce, and hemlock.
• Suitable fibers are commercially available from a number of companies, including the Weyerhaeuser Company.
• suitable cellulose fibers produced from southern pine that are usable in making the present invention are available from the Weyerhaeuser Company under the designations CF416, CF405, NB416, NF405, FR416, and FR516.
• Wood pulp fibers suitable for use in accordance with the present disclosure can also be pretreated prior to use.
• This pretreatment may include physical treatment, such as subjecting the fibers to steam, or chemical treatment.
• pretreating fibers include the application of fire retardants to the fibers, and surfactants or other liquids, such as solvents, which modify the surface chemistry of the fibers.
• Other pretreatments include incorporation of antimicrobials, pigments, and densification or softening agents. Fibers pretreated with other chemicals, such as thermoplastic or thermosetting resins may be used as well.
• Another kind of physical pretreatment is subjecting the fibers to plasma, including corona discharge, to improve the impregnation process of the crosslinking agent. Combinations of pretreatments may also be employed.
• Polyacrylic acid crosslinked cellulosic fibers suitable for use in accordance with the present disclosure may be prepared by a system and apparatus as described in U.S. Pat. No. 5,447,977, for example.
• the following description of the crosslinking process refers to this system as an illustrative example, although any suitable system may be employed.
• the system includes a conveying device for transporting a mat or web of cellulose fibers through a fiber treatment zone; an applicator for applying a treatment substance from a source to the fibers at the fiber treatment zone; a fiberizer for separating the individual cellulose fibers comprising the mat to form a fiber output comprised of substantially unbroken and essentially singulated cellulose fibers; a dryer coupled to the fiberizer for flash evaporating residual moisture; and a controlled temperature zone for additional heating of fibers and an oven for curing the crosslinking agent, to form dried and cured individualized crosslinked fibers.
• the term “mat” refers to any nonwoven sheet structure comprising cellulose fibers or other fibers that are not covalently bound together.
• the fibers include fibers obtained from wood pulp or other sources including cotton rag, hemp, grasses, cane, cornstalks, cornhusks, or other suitable sources of cellulose fibers that may be laid into a sheet.
• the mat of cellulose fibers is preferably in an extended sheet form, and may be one of a number of baled sheets of discrete size or may be a continuous roll.
• Each mat of cellulose fibers is transported by a conveying device, for example, a conveyor belt or a series of driven rollers.
• the conveying device carries the mats through the fiber treatment zone.
• a crosslinking agent solution is applied to the mat of cellulose fibers.
• the crosslinking agent solution is applied to one or both surfaces of the mat using any one of a variety of methods known in the art, including spraying, rolling, or dipping. Once the crosslinking agent solution has been applied to the mat, the solution may be uniformly distributed through the mat, for example, by passing the mat through a pair of rollers.
• the impregnated mat is fiberized by feeding the mat through a hammermill.
• the hammermill disintegrates the mat into its component individual cellulose fibers, which are then air conveyed through a drying unit to remove the residual moisture.
• the fibrous mat is wet fiberized.
• the resulting treated pulp is then air conveyed through an additional heating zone (e.g. a dryer) to bring the temperature of the pulp to the cure temperature.
• the dryer includes a first drying zone for receiving the fibers and removing residual moisture from the fibers via a flash-drying method, and a second heating zone for curing the crosslinking agent, to allow the chemical reaction (esterification, in this embodiment), to be completed.
• the treated fibers are blown through a flash-dryer to remove residual moisture, heated to a curing temperature, and then transferred to an oven where the treated fibers are subsequently cured.
• the treated fibers are dried and then cured for a sufficient time and at a sufficient temperature to achieve crosslinking.
• the fibers are oven-dried and cured for about 1 to about 20 minutes at a temperature from about 120° C. to about 200° C.
• the pH of the fibers is generally around 4.5 to 5.
• a bleaching stage typically follows the curing stage.
• this disclosure provides methods for making bleached polyacrylic acid crosslinked cellulosic fibers.
• polyacrylic acid crosslinked cellulosic fibers are subsequently treated—that is, treated after crosslinking reaction is completed and the fibers are cured—with one or more bleaching agents to provide polyacrylic acid crosslinked cellulosic fibers having reduced amounts of furfural, and accompanying reduced malodor.
• the bleaching agent is applied to the polyacrylic acid crosslinked cellulosic fibers.
• the bleaching agent is hydrogen peroxide.
• the bleaching agent is a combination of hydrogen peroxide and sodium hydroxide.
• Other possible bleaching agents include peroxy acids (e.g. peracetic acid), sodium peroxide, chlorine dioxide, sodium chlorite, and sodium hypochlorite. Mixture of bleaching agents may also be used. Due to environmental and health concerns, bleaching agents other than chlorine-containing agents are generally preferred.
• the polyacrylic acid crosslinked cellulosic fibers can be treated with from about 0.1 pounds (0.045 kg) to about 20 pounds (9.07 kg) hydrogen peroxide per air dried metric ton of fiber.
• An air dry metric ton also referred to as “ADMT” (2204.6 lbs, or 1000 kg), is a weight measurement for wood pulp.
• AdMT air dry metric ton
• an air dry metric ton has a dry solids (fiber) content of 90%.
• the aforementioned range corresponds to about 0.005 wt % to about 1.01 wt % chemical on pulp (“COP”).
• the fibers are treated with from about 3 pounds (1.36 kg) to about 10 pounds (4.54 kg) hydrogen peroxide per ADMT of fiber (about 0.15 wt % to about 0.5 wt % COP). In some embodiments, the fibers are treated with about 5 pounds (2.27 kg) hydrogen peroxide per ADMT of fiber (about 0.25 wt % COP).
• the amount of hydrogen peroxide may, in some environments, be limited by factors such as safe chemical handling practice, application method(s), application apparatus, and so forth. However, the disclosure is not so limited, and encompasses any level of hydrogen peroxide effective to reduce furfural levels in polyacrylic acid crosslinked cellulose fibers.
• the bleaching agent is applied to polyacrylic acid crosslinked cellulosic fibers immediately after curing by spraying hydrogen peroxide onto the fibers by any suitable means.
• this may be accomplished by spraying moistened polyacrylic acid crosslinked fibers placed into a mylar aluminum sealable bag with an aqueous solution of hydrogen peroxide.
• this can be accomplished by spraying an aqueous solution of hydrogen peroxide into an air stream containing polyacrylic acid crosslinked fibers. Any suitable application method may be used.
• the hydrogen peroxide is applied to polyacrylic acid crosslinked cellulosic fibers in the presence of alkaline agents such as sodium hydroxide.
• alkaline agents such as sodium hydroxide.
• up to 5 pounds sodium hydroxide per ADMT of fiber can be applied to the fibers together with the hydrogen peroxide.
• the hydrogen peroxide is applied in the absence of sodium hydroxide, and/or in the absence of any alkaline or other bleaching agents.
• the pH of the hydrogen peroxide solution applied to the fibers is between about 4.5 and 5.
• hydrogen peroxide is applied to polyacrylic acid crosslinked cellulosic fibers alone, that is, in the absence of any other chemical compound or reagent besides water.
• Furfural amount or content can be measured by any suitable method, such as standard GC-FID methods or otherwise, and the reduction of furfural content can be calculated by comparing the content measured at two (or more) different times after furfural is initially generated. Due to the different reaction rates of initial furfural generation and subsequent furfural reduction, it was found that furfural measurements were best taken at two points between 1 and 21 days after hydrogen peroxide treatment. For example, in a mill environment, it is typical that the cured fibers, after bleaching, are baled while still retaining heat from the curing stage, and thus it is possible that this residual heat may prolong the furfural generation reaction (even after hydrogen peroxide treatment and initiation of the furfural reduction reaction) until the fibers have cooled.
• any suitable method such as standard GC-FID methods or otherwise, and the reduction of furfural content can be calculated by comparing the content measured at two (or more) different times after furfural is initially generated. Due to the different reaction rates of initial furfural generation and subsequent furfural reduction,
• initial furfural measurements were taken at least one day after treatment with hydrogen peroxide.
• the subsequent furfural measurements were taken after allowing the bleached polyacrylic acid crosslinked cellulosic fibers to be aged, to assure sufficient time for the hydrogen peroxide reduction of furfural content to reach equilibrium.
• the aging may take place as the fibers are processed or handled after treatment. For example, in a mill environment, after bleaching, the crosslinked fibers are typically conveyed to a baling device in which the product fibers are baled and wrapped prior to shipment.
• Samples of polyacrylic acid crosslinked cellulose fibers were prepared on lab scale by treating southern pine kraft pulp fibers (CF416, Weyerhaeuser Co.) with polyacrylic acid (Aquaset 1676, Dow). All samples were treated with a standard crosslinking solution and cured at 193° C. (380° F.) for 5 minutes. The cured fibers were remoisturized either with distilled water (as control) or with water containing the bleaching agent hydrogen peroxide (H 2 O 2 ) at concentrations of 2.5, 5.0, 7.5, and 10.0 lbs/ADMT of fiber (1.13, 2.27, 3.40, and 4.54 kg/ADMT, respectively). The pH of distilled water was 4.46, and that of the respective H 2 O 2 solutions were 4.93, 4.72, 4.80, and 4.65.
• distilled water was 4.46, and that of the respective H 2 O 2 solutions were 4.93, 4.72, 4.80, and 4.65.
• a Headspace Sampler HP 7694
• Volatile compounds are driven off of the pulp into the headspace in the form of vapors.
• the Headspace Sampler injects the gas sample, via a 0.5 ml sample loop, onto a HP 5890 Series II Gas Chromatograph (GC).
• GC Gas Chromatograph
• a 30 meter megabore column (DB624 0.054 mm ID, 3.0 micron film thickness) separates the compounds by a combination of boiling point, molecular weight and vapor pressure—as the GC oven heats up, the compounds elute off of the column and are detected by a flame ionization detector (FID).
• the resulting graph is represented by distinct peaks over the time of the analysis.
• the data is acquired by HP Chemstation software and analyzed by Thermo Target Software.
• the compound is identified by its unique retention time and the intensity (the peak area) indicates the amount.
• nine different concentrations were used to generate a calibration curve, with a range from 0.02-12 ⁇ g/g (ppm).
• the calibration curve had a regression of R squared of 0.999.
• Samples of polyacrylic acid crosslinked cellulose fibers were prepared on lab scale according to the procedure described in Example 1. However, after treatment with crosslinking solution, samples were cured at 193° C. (380° F.) for 10 minutes in order to enhance initial levels of furfural resulting from curing. The cured fibers were remoisturized either with water (control), or with water containing the bleaching agent hydrogen peroxide (H 2 O 2 ) at concentrations of 2.5, 5.0, 7.5, and 10.0 lbs/ADMT (1.13, 2.27, 3.40, and 4.54 kg/ADMT) of fiber.
• control water containing the bleaching agent hydrogen peroxide
• Some cured fibers were treated with water containing H 2 O 2 (at concentrations of 2.5 and 5.0 lbs/ADMT (1.13 and 2.27 kg/ADMT) fiber) and sodium hydroxide (NaOH) (at a concentration of either 2.5 or 5.0 lbs/ADMT (1.13 or 2.27 kg/ADMT) fiber).
• H 2 O 2 at concentrations of 2.5 and 5.0 lbs/ADMT (1.13 and 2.27 kg/ADMT) fiber
• NaOH sodium hydroxide
• furfural content of the treated samples generally decreased as the amount of hydrogen peroxide applied increased, comparing Day 1 values to that of the untreated control sample (2A), with reductions ranging from approximately 32% (in sample 2B) to approximately 51% (in sample 2H). Furfural content at Day 1 was slightly less in the samples treated with sodium hydroxide in addition to hydrogen peroxide, as compared with the samples treated with the same amount of hydrogen peroxide alone.
• Example 2 the furfural reduction compared to the untreated control sample (2A) was greatest in sample 2H (at 10.0 lbs/ADMT (4.54 kg/ADMT) of fiber) at Day 14, at approximately 62%.
• the polyacrylic acid crosslinked cellulosic fibers were cured in a curing bin at temperature of about 182° C. (360° F.) for about 4.5-5 minutes.
• the furfural reduction at Day 21 compared to the untreated control sample (3A) was approximately 35.4% in sample 3B (at 2.5 lbs/ADMT (1.13 kg/ADMT) of fiber), approximately 58.4% in sample 3C (at 3.5 lbs/ADMT (1.59 kg/ADMT) of fiber), and approximately 78.2% in sample 3D (at 5.0 lbs/ADMT (2.27 kg/ADMT) of fiber).
• the bleached polyacrylic acid crosslinked cellulosic fibers produced in accordance with the present disclosure are suitable for incorporation into a variety of products, including, for example, paper boards, tissues, towels, and wipes, and personal care absorbent products, such as infant diapers, incontinence products, and feminine care products.
• the disclosure provides absorbent products including wipes, towels, and tissues as well as infant diapers, adult incontinence products and feminine hygiene products that include bleached polyacrylic acid crosslinked cellulosic fibers with reduced levels of furfural and accompanying malodor.

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