Odor control pulp composition

Abstract

The present technology relates to fluff pulp having improved odor control and methods of making such fluff pulp. A fluff pulp is provided that includes bleached kraft fibers and a copper ion content of from about 0.2 ppm to about 50 ppm by weight of the bleached kraft fibers. The bleached kraft fibers include a length-weighted average fiber length of at least about 2 mm, a copper number of less than about 7, a carboxyl content of greater than about 3.5 meq / 100 grams; an ISO brightness of at least 80; and a viscosity of from about 2 cps to about 9 cps.

Description

[0001] This patent application is a divisional of patent application number 201880033138.8 (International Application Number PCT / US2018 / 021991) having applicant “International Paper Company” and having title “Odor Control Pulp Composition”. TECHNICAL FIELD

[0002] The present technology relates generally to fluff pulp having improved odor control and methods of making such fluff pulp. SUMMARY

[0003] In an aspect, a fluff pulp is provided that includes bleached kraft fibers and a copper ion content of about 0.2 ppm to about 50 ppm by weight of the bleached kraft fibers. The bleached kraft fibers include a length-weighted average fiber length of at least about 2 mm, a copper number of less than about 7, a carboxyl content of greater than about 3.5 meq / 100 grams; an ISO brightness of at least 80; and a viscosity of about 2 cps to about 9 cps, wherein the fluff pulp has a copper ion content of about 0.2 ppm to about 50 ppm by weight of the bleached kraft fibers.

[0004] In a related aspect, a process for making a fluff pulp is provided. The process includes treating a lignocellulosic material by adding about 50 ppm to about 200 ppm by weight of the lignocellulosic material of a catalyst consisting of a combination of copper and iron or salts thereof in the presence of about 0.5% to about 5% oxidizing agent by weight of the lignocellulosic material to produce a treated lignocellulosic material. In the process, the weight ratio of iron and iron salts to copper and copper salts is at most about 10:1. The treated lignocellulosic material has a viscosity of about 2 cps to about 6 cps and at least a 50% greater inhibition of ammonia formation compared to a second treated lignocellulosic material formed from the same process without copper. The lignocellulosic material can be a lignocellulosic kraft pulp, such as a lignocellulosic kraft pulp that has been bleached with chlorine dioxide.

[0005] In any embodiment herein, the process can include treating a lignocellulosic kraft pulp by adding about 50 ppm to about 200 ppm by weight of the lignocellulosic kraft pulp of a catalyst in the presence of about 0.5% to about 5% oxidizing agent by weight of the lignocellulosic kraft pulp at an acidic pH to produce a treated lignocellulosic material.

[0006] In any embodiment herein, the process can include treating a lignocellulosic Kraft pulp by adding about 50 ppm to about 150 (or about 200) ppm of a catalyst based on the weight of the lignocellulosic Kraft pulp in the presence of about 0.5% to about 5% oxidant based on the weight of the lignocellulosic Kraft pulp at a pH of about 2.5 to about 5 to produce a treated lignocellulosic material; wherein the lignocellulosic Kraft pulp is in an aqueous solution of about 8 wt% to about 12 wt% lignocellulosic Kraft pulp based on water in solution; the weight ratio of iron and iron salts to copper and copper salts is about 8: 1 to about 1 :8; and the treated lignocellulosic material has a viscosity of about 3 cps to about 5 cps.

[0007] In another related aspect, a process for improving odor control properties of fluff pulp is provided. The process includes treating a first lignocellulosic material by adding about 3.5 ppm to about 200 ppm of a copper salt and about 25 ppm to about 175 (or about 196.5) ppm of an iron salt at a pH of about 1 to about 9 to form a second lignocellulosic material, wherein the weight ratio of the iron salt to the copper salt is about 8: 1 to about 1 : 1; the dried second lignocellulosic material forms an inhibition of ammonia formation that is at least 50% greater than the dried first lignocellulosic material. DETAILED DESCRIPTION

[0008] I. DEFINITIONS

[0009] The following terms are used throughout with the following definitions.

[0010] As used herein and in the appended claims, singular articles such as “a,” “an,” and “the” and similar referents are to be construed as including plural forms unless otherwise indicated or clearly contradicted by context. The specification recites numerical ranges using the abbreviation “about” to indicate that the numerical value is approximate. The use of “about” with a numerical value specifies the value to the nearest tenth of the unit of the value. The recitation of numerical ranges herein is merely intended to serve as a shorthand method of referring individually to each separate numerical value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate embodiments and does not pose a limitation on the scope of the claims unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential.

[0011] As used herein, “about” will be understood by those of ordinary skill in the art and will vary to some extent based, at least in part, on the context in which the term is used. If there is a context present in the description of the application that would render the use of the term “about” with a particular value inoperable, then that particular value will be precise as understood by one of ordinary skill in the art.

[0012] As will be appreciated by one of skill in the art, all ranges disclosed herein include any and all subranges and combinations of subranges thereof, for any and all purposes. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be easily broken down into a lower third, middle third, and upper third. As will also be appreciated by one of skill in the art, all language such as "up to," "at least," "greater than," "less than," and the like include the number recited and refer to ranges with endpoints inclusive of the number recited. Finally, as will be understood by one of skill in the art, ranges include each individual number within the range. Thus, for example, a group having 1-3 atoms refers to groups having 1, 2, or 3 atoms. Similarly, a group having 1-5 atoms refers to groups having 1, 2, 3, 4, or 5 atoms, and so forth.

[0013] As used herein, the term "halide" refers to bromide, chloride, fluoride, or iodide.

[0014] II. The Technology

[0015] Cellulose pulp has been used in various personal care or medical care absorbent products, such as diaper fluff or incontinence products. However, odor caused by body fluids is a major problem, such as ammonia odor from urine in the case of diaper fluff. For other applications, other nitrogen- or sulfur-containing substances can cause malodor problems.

[0016] The technology relates to fluff pulp exhibiting improved odor control and methods of producing such advantageous fluff pulp. The fluff pulp exhibits significantly improved odor control at least in part by using surprisingly low amounts of copper. Although particularly suitable for diaper fluff and incontinence products, the technology is applicable to any situation where odor control is beneficial and / or advantageous.

[0017] Thus, in one aspect, a fluff pulp is provided that includes bleached kraft fibers and a copper ion content of about 0.2 ppm to about 50 ppm by weight of the bleached kraft fibers. The bleached kraft fibers include a length-weighted average fiber length of at least about 2 mm, a copper number of less than about 7, a carboxyl content of greater than about 3.5 meq / 100 grams; an ISO brightness of at least 80; and a viscosity of about 2 cps to about 9 cps. The fluff pulp can or can not include a superabsorbent polymer (SAP), such as sodium polyacrylate polymers and copolymers. The kraft fibers can be derived from softwood fibers, hardwood fibers, or mixtures thereof, with such fibers described in greater detail herein.

[0018] As further described herein and in addition to other features of the fluff pulp, it was surprisingly found that including a copper ion content of from about 0.2 ppm to about 50 ppm by weight of the bleached kraft fibers of copper significantly improved odor control properties compared to a fluff pulp that did not contain copper. In fact, due to the inclusion of such low copper ion content, one of ordinary skill in the art would not expect significant odor control properties.

[0019] The inhibition of ammonia formation by the fluff pulp can be at least 50% greater compared to a second fluff pulp having the same features but without copper (i.e., a fluff pulp having the same composition except that the fluff pulp does not include copper ions). The “inhibition of ammonia formation” is the fluff pulp having less gaseous ammonia compared to a fluff pulp having the same composition except that the fluff pulp does not include copper ions as determined by the tests of Example 1 (absence of SAP) and / or Example 2 (presence of SAP). Without being bound by theory, this inhibition can be due to increased absorption of NH3 in the fluff pulp, prevention of conversion of nitrogen-containing compounds to NH3, or a combination of both. The inhibition can be at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 92%, at least about 94%, at least about 96%, at least about 98%, at least about 99%, about 100%, or any range including and / or between any two of these values.

[0020] The copper ions of the copper ion content can be bound to the bleached kraft fibers and / or can be in the form of a copper (I) salt, a copper (II) salt, a hydrate thereof, or a combination of any two or more thereof. The copper (I) salt includes, but is not limited to, copper (I) chloride, copper (I) oxide, copper (I) sulfate, or a combination of any two or more thereof. The copper (II) salt includes, but is not limited to, copper (II) carbonate, copper (II) chloride, copper (II) phosphate, copper (II) nitrate, copper (II) perchlorate, copper (II) phosphate, copper (II) sulfate, copper (II) tetrafluoroborate, copper (II) triflate, or a combination of any two or more thereof. Non-kraft fiber ligands and / or salts thereof that can be included in the fluff pulp with copper include, but are not limited to, ethylenediaminetetraacetic acid, (S,S')-ethylenediamine-N,N'-disuccinic acid, diethylenetriaminepentaacetic acid, ethylene glycol-bis(2-aminoethyl)-N,N,N',N'-tetraacetic acid, trans-1,2-diaminocyclohexanetetraacetic acid, or a mixture of any two or more thereof. Non-kraft fiber ligands can not be included in the fluff pulp. In contrast to non-kraft fiber ligands, a “kraft fiber ligand” is a portion or moiety of a kraft fiber.

[0021] The copper ion content in the fluff pulp, as determined by the weight of the bleached kraft fibers, can be about 0.2 ppm, about 0.5 ppm, about 1 ppm, about 2 ppm, about 3 ppm, about 4 ppm, about 5 ppm, about 6 ppm, about 7 ppm, about 8 ppm, about 9 ppm, about 10 ppm, about 12 ppm, about 14 ppm, about 16 ppm, about 18 ppm, about 20 ppm, about 22 ppm, about 24 ppm, about 26 ppm, about 28 ppm, about 30 ppm, about 32 ppm, about 34 ppm, about 36 ppm, about 38 ppm, about 40 ppm, about 42 ppm, about 44 ppm, about 46 ppm, about 48 ppm, about 50 ppm, and any range including and / or between any two of these values. The copper ion content can be determined by conventional analytical methods, such as ICP-atomic absorption. Thus, the values for the copper ion content refer to the mass of Cu +1 ions and / or Cu +2 ions themselves, not the total mass of the copper salt (e.g., the total mass of copper sulfate). As a further example, the mass of copper ions in copper sulfate is about 0.4 of the total mass of copper sulfate.

[0022] The fluff pulp can or can not also include iron ions. The iron ions associated with the bleached kraft fibers can be ferrous salts (Fe 2+ ), ferric salts (Fe 3+), hydrates thereof, and combinations of any two or more thereof. The ferrous and / or ferric salts include halides, sulfates, nitrates, phosphates, carbonates, and combinations of any two or more thereof. Examples include, but are not limited to, ferrous sulfate (e.g., ferrous sulfate heptahydrate), ferrous chloride, ammonium ferrous sulfate, ferric chloride, ammonium sulfate or ammonium citrate. The amount of iron ions in the fluff pulp (“iron ion content”) can be from about 0.2 ppm to about 50 ppm by weight of the bleached kraft fibers; thus, the amount of iron ions can be about 0.2 ppm, about 0.5 ppm, about 1 ppm, about 2 ppm, about 3 ppm, about 4 ppm, about 5 ppm, about 6 ppm, about 7 ppm, about 8 ppm, about 9 ppm, about 10 ppm, about 12 ppm, about 14 ppm, about 16 ppm, about 18 ppm, about 20 ppm, about 22 ppm, about 24 ppm, about 26 ppm, about 28 ppm, about 30 ppm, about 32 ppm, about 34 ppm, about 36 ppm, about 38 ppm, about 40 ppm, about 42 ppm, about 44 ppm, about 46 ppm, about 48 ppm, about 50 ppm, or any range including and / or between any two of these values, by weight of the bleached kraft fibers. The iron content can be determined by conventional analytical methods, such as ICP-atomic absorption.

[0023] As previously mentioned, the bleached kraft fibers have a length-weighted average fiber length of at least about 2 mm. The length-weighted average fiber length of the bleached kraft fibers can be about 2 mm, about 2.1 mm, about 2.2 mm, about 2.3 mm, about 2.4 mm, about 2.5 mm, about 2.6 mm, about 2.7 mm, about 2.8 mm, about 2.9 mm, about 3.0 mm, about 3.1 mm, about 3.2 mm, about 3.3 mm, about 3.4 mm, about 3.5 mm, about 3.6 mm, about 3.7 mm, about 3.8 mm, about 3.9 mm, about 4.0 mm, or any other range greater than any of these values, or any range including and / or between any two of these values. Such length-weighted average fiber lengths can be determined according to the manufacturer’s standard procedure by Fiber Quality Analyzer Model 2000® available from OPTEST of Hawkesbury, Ontario, Canada. TM

[0024] ​The bleached kraft fibers have a copper number of less than about 7. The copper number can be measured according to TAPPI T430-cm99. The bleached kraft fibers can have a copper number of about 1, about 2, about 3, about 4, about 5, about 6, about 7, or any range less than any of these values, or any range including and / or between any two of these values. The bleached kraft fibers also have a carboxyl content of greater than about 3.5 meq / 100 grams, where the carboxyl content can be measured according to TAPPI T237-cm98. Thus, the bleached kraft fibers can have a carboxyl content (in meq / 100 grams) of about 3.6, about 3.8, about 4.0, about 4.5, about 5, about 5.5, about 6, about 6.5, about 7, about 7.5, about 8, or any range including and / or between any two of these values. The carboxyl content can be measured according to TAPPI T237-cm98.

[0025] The bleached kraft fibers of the fluff pulp have an ISO brightness of at least 80. The ISO brightness can be determined according to TAPPI T525-om02. The bleached kraft fibers can have an ISO brightness of 80, about 82, about 84, about 86, about 88, about 90, about 91, about 92, about 93, about 94, about 95, or any range including and / or between any two of these values. In any embodiment herein, the bleached kraft fibers can not include a fluorescent whitening agent. In any embodiment herein, the fluff pulp can not include a fluorescent whitening agent.

[0026] As previously described herein, the bleached kraft fibers of the fluff pulp have a viscosity of about 2 cps to about 9 cps. The viscosity of the bleached kraft fibers can be determined according to the procedure of TAPPI T230-om99. Thus, the bleached kraft fibers can have a viscosity of about 2, about 2.5, about 3, about 3.5, about 4, about 4.5, about 5, about 5.5, about 6, about 6.5, about 7, about 7.5, about 8, about 8.5, about 9, or any range including and / or between any two of these values.

[0027] In related aspects, a process for making fluff pulp is provided. The process includes treating a lignocellulosic material by adding about 50 ppm to about 200 ppm, by weight of the lignocellulosic material, of a catalyst consisting of a combination of copper and / or a salt thereof and iron and / or a salt thereof in the presence of about 0.5% to about 5% oxidizing agent, by weight of the lignocellulosic material, to produce a treated lignocellulosic material. In the process, the weight ratio of iron and iron salts to copper and copper salts is at most about 10: 1. The treated lignocellulosic material has a viscosity of about 2 cps to about 6 cps and at least a 50% greater inhibition of formation of ammonia compared to a second treated lignocellulosic material formed from the same process without copper. The inhibition can be at least about 50% greater, at least about 55% greater, at least about 60% greater, at least about 65% greater, at least about 70% greater, at least about 75% greater, at least about 80% greater, at least about 85% greater, at least about 90% greater, at least about 92% greater, at least about 94% greater, at least about 96% greater, at least about 98% greater, at least about 99% greater, about 100% greater, or any range including and / or between any two of these values.

[0028] The lignocellulosic material can preferably be wood pulp. The lignocellulosic material can be in fibrous and / or particulate form, such as pulp fibers, fines and / or other pulp fragments, hemicellulose, starch, and / or polysaccharide particles and powders. The lignocellulosic material can also include cellulose derivatives, such as carboxymethyl cellulose, hydroxypropyl cellulose, and the like. Useful lignocellulosic materials include, but are not limited to, those derived from known sources of such materials, such as plants. An example of a useful lignocellulosic material is a polysaccharide, such as starch, as described in U.S. Patent No. 8,007,635, which is incorporated herein by reference. An exemplary lignocellulosic material used in the processes described in any of the embodiments herein is pulp fiber, which is used to form paper towels, tissues, diapers, feminine hygiene and adult incontinence products, and to make other types of pulp products, paper and / or paperboard. Such pulp fibers include those derived from hardwood trees, softwood trees, or a combination of hardwood and softwood trees prepared for use in papermaking equipment by any known suitable digestion, refining, and / or bleaching operations (e.g., known mechanical, thermomechanical, chemical and semi-chemical, and other pulping methods known to those of ordinary skill in the art). As used herein, the term "hardwood pulp" refers to fibrous pulp derived from woody material of deciduous trees (angiosperms), while "softwood pulp" refers to fibrous pulp derived from woody material of coniferous trees (gymnosperms). Useful pulp fibers can be provided from non-woody herbaceous plants, including but not limited to kenaf, hemp, jute, flax, sisal, and / or abaca, although legal restrictions and other considerations can make utilization of hemp and other fiber sources impractical or impossible. Bleached or unbleached pulp fibers, such as unbleached kraft pulp and bleached kraft pulp (collectively "lignocellulosic kraft pulp"), and / or recycled pulp can be used in any of the embodiments of the processes described herein. The pulp can have undergone any treatment history normal in pulping and bleaching, or can have been intentionally modified, such as controlled pre-hydrolysis and / or alkali extraction of the fragments prior to kraft pulping, acid and / or enzymatic (e.g., cellulase and / or hemicellulase) hydrolysis of the kraft pulp, and / or "cold soda" treatment of the pulp (to silk strength).

[0029] "Copper and / or a salt thereof" means elemental copper (Cu 0), copper (I) salts, copper (II) salts, hydrates thereof, or combinations of any two or more thereof. Copper (I) salts include, but are not limited to, copper (I) chloride, copper (I) oxide, copper (I) sulfate, or combinations of any two or more thereof, copper (II) salts include, but are not limited to, copper (II) carbonate, copper (II) chloride, copper (II) phosphate, copper (II) nitrate, copper (II) perchlorate, copper (II) phosphate, copper (II) sulfate, copper (II) tetrafluoroborate, copper (II) triflate, or combinations of any two or more thereof. In any embodiment herein, the copper and / or salt thereof can be added in an amount of about 3.5 ppm to about 199.8 ppm by weight of the lignocellulosic material; thus, the copper or salt thereof can be added in an amount of about 3.5 ppm, about 4 ppm, about 4.5 ppm, about 5 ppm, about 5.5 ppm, about 6 ppm, about 7 ppm, about 8 ppm, about 9 ppm, about 10 ppm, about 12 ppm, about 14 ppm, about 16 ppm, about 18 ppm, about 20 ppm, about 22 ppm, about 24 ppm, about 26 ppm, about 28 ppm, about 30 ppm, about 32 ppm, about 34 ppm, about 36 ppm, about 38 ppm, about 40 ppm, about 42 ppm, about 44 ppm, about 46 ppm, about 48 ppm, about 50 ppm, about 55 ppm, about 60 ppm, about 65 ppm, about 70 ppm, about 75 ppm, about 80 ppm, about 85 ppm, about 90 ppm, about 95 ppm, about 100 ppm, about 120 ppm, about 140 ppm, about 160 ppm, about 180 ppm, about 190 ppm, about 199.8 ppm, about 200 ppm, or any range including and / or between any two of these values.

[0030] “Iron and / or salt thereof” means elemental iron (Fe 0 ), ferrous (Fe 2+ ) salts, ferric (Fe 3+) salts, hydrates thereof, and combinations of any two or more thereof. Preferred salts of ferrous and / or ferric salts include halides, sulfates, nitrates, phosphates, carbonates, and combinations of any two or more thereof. Examples include, but are not limited to, ferrous sulfate (e.g., ferrous sulfate heptahydrate), ferrous chloride, ferrous ammonium sulfate, ferric chloride, ferric ammonium sulfate, or ferric ammonium citrate. In any embodiment herein, the amount of iron or salt thereof added can be from about 0.2 ppm to about 180 ppm by weight of the lignocellulosic material; thus, the amount of iron or salt thereof added can be about 0.2 ppm, about 0.5 ppm, about 1 ppm, about 2 ppm, about 3 ppm, about 4 ppm, about 5 ppm, about 6 ppm, about 7 ppm, about 8 ppm, about 9 ppm, about 10 ppm, about 12 ppm, about 14 ppm, about 16 ppm, about 18 ppm, about 20 ppm about 22 ppm, about 24 ppm, about 26 ppm, about 28 ppm, about 30 ppm, about 32 ppm, about 34 ppm, about 36 ppm, about 38 ppm, about 40 ppm, about 42 ppm, about 44 ppm, about 46 ppm, about 48 ppm, about 50 ppm, about 55 ppm, about 60 ppm, about 65 ppm, about 70 ppm, about 75 ppm, about 80 ppm, about 85 ppm, about 90 ppm, about 95 ppm, about 100 ppm, about 120 ppm, about 140 ppm, about 160 ppm, about 180 ppm, or any range including and / or between any two of these values.

[0031] In this process, the weight ratio of iron and iron salts to copper and copper salts is at most about 10: 1. The phrase "at most about 10: 1" means that greater ratios of iron and iron salts to copper and copper salts, such as 11 : 1, are not included, but does not encompass the range of not including iron at all because there is no ratio at all. The weight ratio of iron and iron salts to copper and copper salts can be about 10: 1, about 9: 1, about 8: 1, about 7: 1, about 6: 1, about 5: 1, about 4: 1, about 3: 1, about 2: 1, about 1: 1, about 1:2, about 1:3, about 1:4, about 1:5, about 1:6, about 1:7, about 1:8, about 1:9, about 1: 10, or any range including and / or between any two of these values.

[0032] The oxidizing agent can include one or more of hydrogen peroxide, chlorine dioxide, hypochlorite salts, and hypochlorous acid. A preferred oxidizing agent includes hydrogen peroxide. The amount of oxidizing agent can be about 0.5% to about 5% oxidizing agent by weight of the lignocellulosic material. Thus, the amount of oxidizing agent can be about 0.5%, about 0.6%, about 0.7%, about 0.8%, about 0.9%, about 1%, about 1.2%, about 1.4%, about 1.6%, about 1.8%, about 2%, about 2.2%, about 2.4%, about 2.6%, about 2.8%, about 3%, about 3.2%, about 3.4%, about 3.6%, about 3.8%, about 4%, about 4.2%, about 4.4%, about 4.6%, about 4.8%, about 5%, or any range including and / or between any two of these values.

[0033] The catalyst can be added in the presence of the oxidizing agent by weight of the lignocellulosic material at a pH of about 1 to about 9. The treatment pH can vary widely and any temperature sufficient to form the desired treated lignocellulosic material can be used. The treatment pH can be about 1.0, about 1.5, about 2.0, about 2.5, about 3.0, about 3.5, about 4.0, about 4.5, about 5.0, about 5.5, about 6.0, about 6.5, about 7.0, about 7.5, about 8.0, about 8.5, about 9.0, or any range including and / or between any two of these values. For example, the pH can be an acidic pH (i.e., about 1 to less than about 7), and the pH can preferably be about 2 to about 6, and more preferably about 2.5 to about 5.

[0034] When the amount of another component is determined based on, for example, the weight of the lignocellulosic material, it is based on the dry weight of the lignocellulosic material. The lignocellulosic material (e.g., lignocellulosic kraft pulp) can be in an aqueous solution of about 8 wt% to about 16 wt% of the lignocellulosic material based on water in the solution. Thus, the lignocellulosic material can be in an aqueous solution of about 8 wt%, about 9 wt%, about 10 wt%, about 11 wt%, about 12 wt%, about 13 wt%, about 14 wt%, about 15 wt%, about 16 wt%, or any range including and / or between any two of these values.

[0035] The treatment temperature can vary widely and any temperature sufficient to form the desired treated lignocellulosic product can be used. The treatment temperature is typically at least about 20°C, although lower temperatures can be used if effective to provide the desired lignocellulosic material. The treatment temperature can be about 20°C, about 40°C, about 50°C, about 60°C, about 65°C, about 70°C, about 75°C, about 80°C, about 85°C, about 90°C, about 95°C, about 100°C, about 1 10°C, about 120°C, or any range including and / or between any two of these values. The treatment temperature is preferably about 40°C to about 120°C, more preferably about 40°C to about 90°C, and most preferably about 65°C to about 90°C.

[0036] The treatment time can vary widely and any time sufficient to form the desired treated lignocellulosic product can be used. The treatment time is typically at least about 5 minutes, although longer treatment times can be used if effective to provide the desired lignocellulosic material. The treatment time is preferably about 5 minutes to about 20 hours, more preferably about 15 minutes to about 10 hours, and even more preferably about 30 minutes to about 4 hours. Suitable treatment times include about 5 minutes, about 10 minutes, about 30 minutes, about 1 hour, about one and a half hours, about 2 hours, about 3 hours, about 4 hours, about 6 hours, about 8 hours, about 10 hours, about 15 hours, about 20 hours, or any range including and / or between any two of these values.

[0037] Optionally, the process is performed in the presence or absence of UV radiation, in addition to the catalyst and oxidizing agent, preferably when using hydrogen peroxide as the oxidizing agent. The inclusion of UV radiation has the advantage of being more effective at lower temperatures, e.g., room temperature (or ambient temperature), without the need for heating equipment, and can be used to expand the effective pH range. For example, the process can be effectively performed at ambient temperature (or without heating), at about neutral pH (i.e., about 6.8 to about 7.2), and / or in very short times, e.g., from a few seconds to about 1 hour, depending on the power of the UV lamp, in the presence of UV radiation. The UV lamps used in the process are preferably high intensity lamps, such as medium pressure mercury arc lamps or variations thereof, pulsed xenon flash lamps, or excimer lamps. Most preferably, medium pressure mercury arc lamps are used, which are low cost and readily available from commercial sources. One or more UV lamps, typically inserted in a quartz sleeve, can be inserted (immersed) into the pulp for irradiation. At times, it can be more advantageous to place the UV lamps above the mixed suspension of lignocellulosic material. For this type of UV irradiation, mercury arc lamps and electrodeless powered lamps (such as from Fusion UV Corporation) can be used. The pulp is preferably mixed thoroughly and agitated sufficiently during the reaction, as the UV penetration in water is very low, and most of the chemical action is caused by the UV decomposition of the peroxide in the aqueous solution. In any of the embodiments herein, the UV treatment can be performed with or without the addition of a UV catalyst. Useful UV catalysts include, but are not limited to, micron or nanoparticulate titanium dioxide or zinc oxide photocatalysts; azo-based water-soluble organic catalysts, such as 4,4'-azobis(4-cyanopentanoic acid), 2,2'-azobis(2-methylpropylamidine) dihydrochloride, 2,2'-azobis(2-methylpropionitrile) (AIBN), 1,1'-azobiscyclohexanecarbonitrile (e.g., DuPont catalyst 88), and / or (2,2,6,6-tetramethylpiperidinyl)oxy (TEMPO).

[0038] The process can be performed batch-wise, continuously, or semi-continuously. The process can also be implemented as a process step at the end of a mechanical, semi-chemical, or chemical pulping process, as part of the pulping process, or as a step at the end of a multi-step bleaching process (i.e., without performing further bleaching steps after the treatment step of the process). The process can also be used to treat commercially available papermaking pulp and / or fluff pulp, e.g., by re-slurrying the commercially available papermaking pulp or fluff pulp in a hydro-pulper or similar device. The treatment in a hydro-pulper or similar device has the flexibility to adjust conditions. For example, the treatment can be started at an acidic pH, and after some suitable period of time, the treatment includes adjustment to an alkaline pH by the addition of caustic, and the reaction is continued at the higher pH. This combined acidic-alkaline treatment can be used to change the ratio of carboxyl groups to carbonyl groups in the treated lignocellulosic material.

[0039] The treated lignocellulosic material can have any one or more of the features previously described for fluff pulp (e.g., a length-weighted average fiber length of at least about 2 mm, a copper number of less than about 7, a carboxyl content of greater than about 3.5 meq / 100 grams; an ISO brightness of at least 80; and a viscosity of about 2 cps to about 9 cps, or a combination of any two or more thereof) and any range described herein. In any embodiment herein, and as previously discussed for fluff pulp, the treated lignocellulosic material can have a copper ion content of about 0.2 ppm to about 50 ppm by weight of the treated lignocellulosic material, or any range of copper ion content described herein. In any embodiment herein, and as previously discussed for fluff pulp, the treated lignocellulosic material can have an iron ion content of about 0.2 ppm to about 50 ppm by weight of the treated lignocellulosic material.

[0040] In another related aspect, a process for improving the odor control properties of fluff pulp is provided, wherein the process includes treating a first lignocellulosic material by adding about 0.5 ppm to about 200 ppm of a copper salt at a pH of about 1 to about 9 to form a second lignocellulosic material, wherein the dried second lignocellulosic material has at least 50% greater inhibition of ammonia formation than the dried first lignocellulosic material. The inhibition can be at least about 50% greater, at least about 55% greater, at least about 60% greater, at least about 65% greater, at least about 70% greater, at least about 75% greater, at least about 80% greater, at least about 85% greater, at least about 90% greater, at least about 92% greater, at least about 94% greater, at least about 96% greater, at least about 98% greater, at least about 99% greater, about 100% greater, or any range including and / or between any two of these values. The pH can be about 1.0, about 1.5, about 2.0, about 2.5, about 3.0, about 3.5, about 4.0, about 4.5, about 5.0, about 5.5, about 6.0, about 6.5, about 7.0, about 7.5, about 8.0, about 8.5, about 9.0, or any range including and / or between any two of these values.

[0041] In any embodiment of this process herein, the first lignocellulosic material can not contain more than about 0.2 ppm of copper, and preferably not more than about 0.1 ppm of copper, and more preferably not more than about 0.01 ppm of copper. In any embodiment herein, the first lignocellulosic material can not contain detectable copper as measured by ICP-atomic absorption.

[0042] Copper salts are described above, and the term "copper salt" means a copper salt, a mixture of any two or more copper salts, a hydrate of any one or more of the foregoing, and combinations of any two or more thereof, wherein the copper salt can be added in an amount of about 0.5 ppm, about 0.6 ppm, about 0.7 ppm, about 0.8 ppm, about 0.9 ppm, about 1.0 ppm, about 1.2 ppm, about 1.4 ppm, about 1.6 ppm, about 1.8 ppm, about 2.0 ppm, about 2.5 ppm, about 3.5 ppm, about 4 ppm, about 4.5 ppm, about 5 ppm, about 5.5 ppm, about 6 ppm, about 7 ppm, about 8 ppm, about 9 ppm, about 10 ppm, about 12 ppm, about 14 ppm, about 16 ppm, about 18 ppm, about 20 ppm, about 22 ppm, about 24 ppm, about 25 ppm, about 26 ppm, about 28 ppm, about 30 ppm, about 32 ppm, about 34 ppm, about 36 ppm, about 38 ppm, about 40 ppm, about 42 ppm, about 44 ppm, about 46 ppm, about 48 ppm, about 50 ppm, about 55 ppm, about 60 ppm, about 65 ppm, about 70 ppm, about 75 ppm, about 80 ppm, about 85 ppm, about 90 ppm, about 95 ppm, about 100 ppm, about 120 ppm, about 140 ppm, about 160 ppm, about 180 ppm, about 199.8 ppm, about 200 ppm, or any range including and / or between any two of these values.

[0043] Lignocellulosic materials are also described above. In the process, the lignocellulosic material is preferably bleached kraft pulp, more preferably fluff pulp comprising bleached kraft fibers. The bleached kraft fibers / pulp can have any one or more of the characteristics described for bleached kraft fibers of fluff pulp of the present technology (e.g., a length-weighted average fiber length of at least about 2 mm, a copper number of less than about 7, a carboxyl content of greater than about 3.5 meq / 100 grams, an ISO brightness of at least 80, a viscosity of about 2 cps to about 9 cps, or a combination of any two or more thereof) and any ranges described herein.

[0044] It can also be that the iron salt is added with the copper salt, for example, about 25 ppm to about 175 ppm of the iron salt. The iron salt is previously described, where the term "iron salt" means one iron salt, a mixture of any two or more iron salts, a hydrate of any one or more of the foregoing, and combinations of any two or more thereof. The iron salt can be added in an amount of about 25 ppm, about 26 ppm, about 28 ppm, about 30 ppm, about 32 ppm, about 34 ppm, about 36 ppm, about 38 ppm, about 40 ppm, about 42 ppm, about 44 ppm, about 46 ppm, about 48 ppm, about 50 ppm, about 55 ppm, about 60 ppm, about 65 ppm, about 70 ppm, about 75 ppm, about 80 ppm, about 85 ppm, about 90 ppm, about 95 ppm, about 100 ppm, about 120 ppm, about 140 ppm, about 160 ppm, about 165 ppm, about 170 ppm, about 175 ppm, or any range including and / or between any two of these values. In the process, the weight ratio of the iron salt to the copper salt is at most about 10: 1. The phrase "at most about 10: 1" means that greater ratios of the iron salt to the copper salt are not included, for example, 11: 1, but does not encompass ranges that do not include iron, as there is no ratio at all. The weight ratio of the iron salt to the copper salt can be about 10: 1, about 9: 1, about 8: 1, about 7: 1, about 6: 1, about 5: 1, about 4: 1, about 3: 1, about 2: 1, about 1: 1, about 1:2, about 1:3, about 1:4, about 1:5, about 1:6, about 1:7, about 1:8, about 1:9, about 1: 10, or any range including and / or between any two of these values.

[0045] For example, the process can include treating the first lignocellulosic material to form the second lignocellulosic material by adding about 3.5 ppm to about 200 ppm of the copper salt and about 25 ppm to about 175 ppm of the iron salt at a pH of about 1 to about 9.

[0046] In any embodiment herein, the copper salt (and when applicable, the iron salt) can be added as an aqueous solution. In such embodiments, the process can include treating the first lignocellulosic material to provide a wet lignocellulosic material by adding an aqueous solution of the copper salt (and if applicable, the iron salt) at a pH of about 1 to about 9; and drying the wet lignocellulosic material to form the second lignocellulosic material, where the second lignocellulosic material includes about 0.5 ppm to about 200 ppm of the copper salt (or any previously described range), and when including the iron salt, about 25 ppm to about 175 ppm of the iron salt (or any previously described range). The process can also include drying the wet lignocellulosic material and then fiberizing to form the second lignocellulosic material.

[0047] In any embodiment herein, the second lignocellulosic material can have any one or more of the features previously described for fluff pulp (e.g., a length-weighted average fiber length of at least about 2 mm, a copper number of less than about 7, a carboxyl content of greater than about 3.5 meq / 100 grams; an ISO brightness of at least 80; and a viscosity of about 2 cps to about 9 cps, or a combination of any two or more thereof) and any range described herein. In any embodiment herein, and as previously discussed for fluff pulp, the treated lignocellulosic material can have a copper ion content of about 0.2 ppm to about 50 ppm by weight of the treated lignocellulosic material, or any range of copper ion content described herein. In any embodiment herein, and as previously discussed for fluff pulp, the treated lignocellulosic material can have an iron ion content of about 0.2 ppm to about 50 ppm by weight of the treated lignocellulosic material.

[0048] The treated lignocellulosic material or the second lignocellulosic material can be subjected to a number of subsequent treatments to further modify the properties of the material. For example, in any embodiment herein, the treated lignocellulosic material or the second lignocellulosic material can be treated with a cationic agent that, without being bound by theory, is believed to bind to the reductive functional groups of the treated material. Useful cationic materials can vary widely, including but not limited to cationic nitrogen-containing polymers such as polyamines, l-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC), hexa dimethyl bromomethyl, polyethyleneimine (linear and / or branched), copolymers of diallyl dimethyl ammonium chloride (DADMAC), copolymers of vinyl pyrrolidone (VP) with quaternary ammonium methacrylate diethylaminoethyl ester (DEAMEMA), polyamides, cationic polyurethane latex, cationic polyvinyl alcohol, polyalkylamines, dicyandiamide copolymers, amine glycidyl addition polymers, poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene] dichloride, high charge density polyvinyl amines, polyallylamine (PAH), poly(hexamethylene biguanide hydrochloride) (PHMB), polyamidoamine (or polyethyleneimine); cationic metal ions such as water-soluble aluminum, calcium, and / or zirconium salts; and cationic dendrimers such as (polyamidoamine) dendrimers (PAMAM dendrimers) having amino surface groups, and polypropylenimine dendrimers having amino surface groups. Without being bound by theory, it is believed that treatment with such cationic materials can modify properties such as increasing paper bulk, which is desirable for premium paper, paperboard, tissue, towel, and absorbent products, while maintaining good strength and having reduced water retention value (WRV) and increased freeness.

[0049] The treated lignocellulosic material or second lignocellulosic material can be treated with a micron or nanoparticulate metal oxide, such as aluminum oxide, titanium oxide, zinc oxide, and / or silicon dioxide, where such material is held by the treated lignocellulosic material to modify properties such as colorant fixation, dye fixation, optical brightener fixation, printability, and / or odor control properties. The treated lignocellulosic material or second lignocellulosic material can be treated with a crosslinking material during papermaking or web formation. Exemplary crosslinking materials include water-dispersible or water-soluble di- or polyfunctional carbodiimides and / or polycarbodiimides, such as 1,6-hexamethylene bis(ethylcarbodiimide); 1,8- octamethylene bis(ethylcarbodiimide); 1,10-decamethylene bis(ethylcarbodiimide); 1,12- dodecamethylene bis(ethylcarbodiimide); PEG-bis(propyl(ethylcarbodiimide)); 2,2'- dithioethyl bis(ethylcarbodiimide); 1,1'-dithio-p-phenylene bis(ethylcarbodiimide); and 1,1'- dithio-m-phenylene bis(ethylcarbodiimide). The di- or polyfunctional carbodiimide groups react with the reducing functional groups of the treated lignocellulosic material (or second lignocellulosic material) and crosslink with the fibers of the material within the paper or web structure.

[0050] The treated lignocellulosic material or second lignocellulosic material can be used in situ for conventional purposes, or after separation using conventional product separation techniques. For example, the treated lignocellulosic material or second lignocellulosic material can be used to make a paper or paperboard substrate or web. Methods and apparatus for preparing substrates formed from lignocellulosic fibers are well known in the paper and paperboard arts. See, for example, "Handbook For Pulp & Paper Technologies", Second Edition, G. A. Smook, Angus Wilde Publications (1992), and references cited therein. Any conventional method and apparatus can be used. Preferably, such a process using the treated lignocellulosic material (or second lignocellulosic material) comprises: a) depositing an aqueous suspension of lignocellulosic fibers from the treated lignocellulosic material onto a forming wire of a papermaking machine to form a wet paper or paperboard web; b) drying the wet paper or paperboard web to obtain a dried paper or paperboard web, and c) calendering the dried paper or paperboard web. In addition to these, additional steps known to those of ordinary skill in the art can be employed; for example, a coating step to coat one or more surfaces of the dried paper or paperboard web with a coating comprising a dispersed pigment containing binder, and / or treating the dried paper or paperboard with a sizing agent such as starch at a size press.

[0051] The treated lignocellulosic material or second lignocellulosic material can be used to make absorbent articles, such as diapers, paper towels, wipes, and / or personal hygiene products using conventional processes. Such products and methods of making them are known to those of ordinary skill in the art. See, for example, U.S. Patent Nos. 6,063,982 and 5,766,159 (both of which are incorporated herein by reference except for any portions that can contradict the present teachings), and the references described therein. The treated lignocellulosic kraft pulp (which must include treated kraft pulp fibers) can be used to make saturated kraft paper. Saturated kraft paper is a paper sheet made from unbleached kraft pulp (typically a mixture of mostly hardwood and some softwood (e.g., southern pine)) that is used as a substrate for impregnation and solidification with a resin polymer. Saturated kraft paper is used as a building material for home and office, such as kitchen countertops. Useful properties of saturated kraft paper are to control the rate of liquid (typically a polymer resin solution) penetration into the sheet, while maintaining paper porosity and density. All of the hardwood kraft fibers in a saturated sheet can be replaced with softwood (e.g., southern pine kraft (paperboard grade pine kraft) treated by the process of any of the embodiments herein) to provide a saturated kraft paper with good liquid transport properties.

[0052] Examples

[0053] The examples herein are provided to illustrate advantages of the present technology and to further assist those of ordinary skill in preparing or using the processes of the present technology. The examples herein are also given to provide a more thorough description of the preferred aspects of the present technology. The examples should in no way be construed as limiting the scope of the present technology. The examples can include or encompass any variation, embodiment, or aspect of the present technology described above. Variations, embodiments, or aspects described above can further each include or encompass variations of any or all other variations, embodiments, or aspects of the present technology.

[0054] Example 1. Technique for measuring the ammonia inhibition properties of fluff pulp without SAP.

[0055] A sheet of fluff pulp was cut into 2 inch strips and fiberized using a Kamas H01 lab beater. The fiberized pulp was formed into air-laid mats of 50 mm diameter using an air-laid mat former. Each mat was made from 4 grams of fiberized pulp, unless otherwise noted. The mats were compressed to a density of about 0.15 g / cc in a engraved press. Two compressed mats were placed in a closed 1 liter bottle. A 1.0% urease solution (urease from Canavalia ensiformis (Jack Bean), purchased from Sigma) in 40 mL of freshly prepared synthetic urine (RICCA Chemical Company) was added to each 4 gram mat and the bottle was sealed. After 8 hours, the ammonia concentration in the headspace of the bottle was detected using a Draeger tube. As provided by the procedure, the lower the concentration of ammonia, the better the ammonia inhibition effect of the fiberized fluff pulp.

[0056] Example 2. Technique for measuring the ammonia inhibition properties of fluff pulp with SAP.

[0057] A sheet of fluff pulp was cut into 2 inch strips and fiberized using a Kamas H01 lab beater. The fiberized pulp was mixed with SAP for a total weight of 10 grams. For example, if a 10% SAP pad was desired, 9 grams of fiberized pulp was mixed with 1 gram of SAP. The SAP used was Tembond® 9400 (BASF), unless otherwise noted. The mixture of fiberized pulp and SAP was then fed into an air-laid pad former to form a 100 cm 2 circular pad. The pad was compressed to approximately 0.15 g / cc using a engraved press. The pad was placed into a 7 liter closed container. 100 ml of a 1.0% urease solution (described in Example 1) was added to the pad and the container was sealed. After 8 hours, the ammonia concentration in the headspace of the container was detected using a Draeger tube.

[0058] Example 3.

[0059] Pulp was collected after the first chlorine dioxide brightening (D1) stage in an industrial scale D0E op D1D2 bleaching sequence and had a viscosity of 16.5 cps. The pulp was treated in acidic bleaching stages containing different types and amounts of metal salts as shown in Table 1. Each treatment used 100 grams of dry pulp at a consistency of 10% (i.e. 10 wt% pulp in solution) and 3% hydrogen peroxide (i.e. 3 wt% based on pulp) at a temperature of 85°C for a time of 130 minutes.

[0060] After treatment, the pulp was washed with 4L of deionized water and thickened to approximately 20% solids content. The thickened pulp was then diluted with deionized water to approximately 1% consistency and formed into 750 gsm handsheets on an 8 inch by 8 inch handsheet mold. The wet pulp sheet was pressed between blotter papers to remove excess liquid and subsequently dried on a rotary drum dryer at 250°F. The dried sheets were then explored for ammonia inhibition properties with and without SAP as described in Examples 1 and 2. As shown in Table 1, the use of as low as 25 ppm CuSO4 in combination with FeSO4 had a significant inhibitory effect on ammonia formation: the ammonia inhibition without SAP was approximately 50% (100% - (3 ppm NH3 / 6 ppm NH3 x 100%) = 50%) when 25 ppm CuSO4 was used in the acidic peroxide bleaching compared to entry 1. Moreover, the ammonia inhibition without SAP was 100% when 50 ppm CuSO4 was used in combination with 55 ppm FeSO4, and the ammonia inhibition was approximately 82% when 10% SAP was included.

[0061] Table 1.

[0062]

[0063] Example 4.

[0064] Commercial production conditions were performed at International Paper's Riegelwood paper mill in North Carolina. The mill used DOE op D1D2 bleaching sequences were used to bleach kraft softwood pulp. The D2 stage was altered to produce low viscosity pulp using 3% hydrogen peroxide and metal salts, where the composition and amount of metal salts were varied. The first pulp was produced using 150 ppm FeSO4 as the only metal salt (entry 1, Table 2). The second pulp was produced using 125 ppm FeSO4 and 25 ppm CuSO4 (entry 2, Table 2). Both of these reaction conditions resulted in low viscosity pulp.

[0065] Each pulp was then made into a fluff pulp sheet on a Fourdrinier paper machine with a cylindrical steam heated can dryer. Samples of each dried sheet were then collected and tested for ammonia inhibition as described in Examples 1 and 2. As shown in Table 2, as little as 25 ppm CuSO4 used in the acidic hydrogen peroxide bleaching stage had a significant inhibitory effect on ammonia formation. This result was found for both pads made with and without SAP.

[0066] Table 2.

[0067]

[0068] Example 5.

[0069] Fluff pulp sheets (RW Plus; commercially produced by International Paper) were immersed in a deionized water bath at room temperature (72 °F) for one minute, and the concentration of copper (II) sulfate pentahydrate (CuSO4-5H2O) was increased. After the immersion procedure, the pulp sheets were pressed between blotter paper to remove excess liquid and the sheets were dried on a rotary drum dryer at 250 °F. The dried sheets were then tested for ammonia inhibition as described in Examples 1 and 2, where Table 3 shows the results of these tests. As little as 1.0 ppm Cu 2+ had a significant inhibitory effect on ammonia formation.

[0070] Table 3.

[0071]

[0072]

[0073] Example 6.

[0074] A sheet of fluff pulp (RW Plus; commercially produced by International Paper) was sprayed with different aqueous solutions containing deionized water and different concentrations of copper (II) sulfate pentahydrate (CuS04-5H20). The fluff pulp sheet was sprayed until it became visibly wet. After the spraying procedure, each pulp sheet was pressed between blotter papers to remove excess liquid and the sheet was dried on a rotary drum dryer at 250 °F. Each dried sheet was then tested for ammonia inhibition as described in Example 1, where Table 4 shows the results of these tests. Cu 2+ had a significant inhibitory effect on ammonia formation.

[0075] Table 4.

[0076]

[0077] The present technology is not limited to the particular examples described herein, which are intended as individual illustrations by which the general principles of various aspects of the present technology can be better understood. Numerous modifications and changes will be readily apparent to those skilled in the art having the benefit of this disclosure. Accordingly, the present technology is not intended to be limited to the specific methods described herein, which can vary as particular implementation dictates. It is therefore to be understood that the present technology is not to be limited to particular methods, reagents, compounds, compositions, or labeled compounds, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.

[0078] Embodiments, illustratively described herein can be suitably practiced in the absence of any element or elements, limitation or limitations that are not specifically disclosed herein. Thus, for example, the terms "comprising," "including," containing", and the like, shall be read expansively and without limitation. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is also taken into account the possession of features by a single alternative that enables a claim directed to less than all features of the alternative to also cover functionally equivalent alternatives that do not possess all of the features. Additionally, the phrase "consisting essentially of will be understood to include those elements specifically recited and not additional elements that do not materially affect the basic and novel characteristics of the claimed technology. The phrase "consisting of excludes any element not specified.

[0079] Further, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group. Each of the narrower species and subgeneric groupings falling within the generic scope of the general description also form part of the application. This includes specific embodiments of the application, which are appended hereto and which follow in the specification. Generally, the nomenclature used herein and the laboratory procedures utilized in the

[0080] All publications, patent applications, issued patents, and other documents (for example, journals, articles and / or textbooks) cited in this specification are herein incorporated by reference as if each individual publication, patent application, issued patent, or other document was specifically and individually indicated to be incorporated by reference. Definitions that are contained in text incorporated by reference are excluded to the extent that text lists definitions as reported in patent application publication US 2006-0172415-A1 and are definitions other than those reported in patent application publication US 2006-0172415-A1.

[0081] Other embodiments are set forth in the following claims, and the entirety of the range of equivalents afforded by such claims.

Claims

1. An airlaid pulp comprising: bleached kraft fibers, the bleached kraft fibers comprising: a length-weighted average fiber length of at least 2 mm; a copper number of less than 7; and an ISO brightness of at least 80; and a copper ion content of 1.0 ppm to 5.0 ppm by weight of the bleached kraft fibers, wherein the airlaid pulp does not comprise a superabsorbent polymer.

2. The airlaid pulp of claim 1, wherein the copper ions of the copper ion content comprise a copper (I) salt, a copper (II) salt, a hydrate thereof, or a combination of any two or more thereof.

3. The airlaid pulp of claim 1, wherein the copper ions of the copper ion content comprise one or more of: elemental copper, copper (I) chloride, copper (I) oxide, copper (I) sulfate, copper (II) carbonate, copper (II) chloride, copper (II) phosphate, copper (II) nitrate, copper (II) perchlorate, copper (II) phosphate, copper (II) sulfate, copper (II) tetrafluoroborate, and copper (II) triflate.

4. The airlaid pulp of claim 1, wherein the airlaid pulp further comprises iron ions.

5. The airlaid pulp of claim 4, wherein the airlaid pulp comprises an iron ion content of 0.2 ppm to 50 ppm by weight of the bleached kraft fibers.

6. The airlaid pulp of claim 1, wherein the airlaid pulp has a carboxyl content of greater than 3.5 meq / 100 grams.

7. The airlaid pulp of claim 1, wherein the airlaid pulp has a copper ion content of 1.0 ppm to 3.7 ppm by weight of the bleached kraft fibers.

8. The airlaid pulp of claim 1, wherein the inhibition of ammonia formation by the airlaid pulp is 22 ppm of ammonia or less after 8 hours of an ammonia generation test of the airlaid pulp without a superabsorbent polymer, the ammonia generation test comprising the steps of: i) cutting the airlaid pulp into 2 inch strips and fiberizing them using a Kamas H01 laboratory beater to produce a fiberized airlaid pulp; ii) forming the fiberized airlaid pulp into an air-laid mat of 50 mm in diameter using an air-laid mat former; iii) each mat is made from 4 grams of fiberized airlaid pulp and the mat is compressed to a density of 0.15 g / cc in a engraved press; iv) two compressed mats are placed in a closed 1 liter bottle; v) a 1.0% urease solution in 40 mL of freshly prepared synthetic urine is added to each 4 gram mat and the bottle is sealed; and vi) the ammonia concentration in the headspace of the bottle is detected using a Draeger tube.

9. The airlaid pulp of claim 8, wherein the copper ions of the copper ion content comprise a copper (I) salt, a copper (II) salt, a hydrate thereof, or a combination of any two or more thereof.

10. The fluff pulp of claim 8, wherein the copper ion content of copper ions comprises one or more of: elemental copper, copper (I) chloride, copper (I) oxide, copper (I) sulfate, copper (II) carbonate, copper (II) chloride, copper (II) phosphate, copper (II) nitrate, copper (II) perchlorate, copper (II) phosphate, copper (II) sulfate, copper (II) tetrafluoroborate, and copper (II) triflate.

11. The fluff pulp of claim 8, wherein the fluff pulp further comprises iron ions.

12. The fluff pulp of claim 11, wherein the fluff pulp comprises an iron ion content of 0.2 ppm to 50 ppm by weight of the bleached kraft fibers.

13. The fluff pulp of claim 8, wherein the fluff pulp has a carboxyl content of greater than 3.5 meq / 100 grams.

14. A process for making the fluff pulp of claim 1, the process comprising: adding 1.0 ppm to 5.0 ppm of copper or a salt thereof by weight of the bleached kraft fibers to treat the bleached kraft fibers to produce the fluff pulp; wherein the fluff pulp has at least a 50% greater inhibition of ammonia formation compared to a second bleached kraft fiber formed by the same process without copper.

15. The process of claim 14, wherein the copper or salt thereof consists of one or more of the following: The element copper Cu 0 , copper (I) and copper (II) salts.

16. The process of claim 14, wherein the copper or salt thereof consists of: elemental copper, copper (I) chloride, copper (I) oxide, copper (I) sulfate, copper (II) carbonate, copper (II) chloride, copper (II) phosphate, copper (II) nitrate, copper (II) perchlorate, copper (II) phosphate, copper (II) sulfate, copper (II) tetrafluoroborate, copper (II) triflate, hydrates thereof, or combinations of any two or more thereof.

17. The process of claim 14, further comprising bleaching kraft fibers with a multi-step bleaching process to produce bleached kraft fibers, wherein the treating occurs after the bleaching.

18. The process of claim 14, further comprising bleaching kraft fibers with a multi-step bleaching process to produce bleached kraft fibers, wherein no additional bleaching occurs after the treating.

19. The process of claim 14, wherein the fluff pulp has a carboxyl content of greater than 3.5 meq / 100 grams.

20. The process of claim 14, wherein the fluff pulp further comprises iron ions.

21. The process of claim 20, wherein the fluff pulp comprises an iron ion content of 0.2 ppm to 50 ppm by weight of the bleached kraft fibers.

22. The process of claim 14, comprising adding 1.0 ppm to 3.7 ppm of copper or a salt thereof by weight of the bleached kraft fibers to treat the bleached kraft fibers to produce the fluff pulp.

23. A process for improving odor control properties of fluff pulp, the process comprising: adding 1.0 ppm to 5.0 ppm of copper or a salt thereof by weight of the lignocellulosic material to treat bleached kraft fibers to produce the fluff pulp; wherein the fluff pulp has at least 50% greater inhibition of ammonia formation compared to a second treated lignocellulosic material formed from the same process without copper wherein the fluff pulp does not include a superabsorbent polymer.

24. The process of claim 23, wherein the fluff pulp includes 1.0 ppm to 3.7 ppm of copper ions by weight of the fluff pulp.

25. The process of claim 23, wherein the fluff pulp further includes iron ions.

26. The process of claim 25, wherein the fluff pulp includes an iron ion content of 0.2 ppm to 50 ppm by weight of the bleached kraft fibers.

27. A process for making the fluff pulp of claim 8, the process comprising: adding copper or a salt thereof to bleached kraft fibers to treat the bleached kraft fibers to produce the fluff pulp; wherein the fluff pulp has at least 50% greater inhibition of ammonia formation compared to a second bleached kraft fiber formed from the same process without copper.

28. The process of claim 27, wherein the copper or salt thereof consists of one or more of the following: The element copper Cu 0 copper (I) and copper (II) salts.

29. The process of claim 27, wherein the copper or salt thereof consists of: elemental copper, copper (I) chloride, copper (I) oxide, copper (I) sulfate, copper (II) carbonate, copper (II) chloride, copper (II) phosphate, copper (II) nitrate, copper (II) perchlorate, copper (II) phosphate, copper (II) sulfate, copper (II) tetrafluoroborate, copper (II) triflate, a hydrate thereof, or a combination of any two or more thereof.

30. The process of claim 27, further comprising bleaching kraft fibers with a multi-step bleaching process to produce bleached kraft fibers, wherein the treating occurs after the bleaching.

31. The process of claim 27, further comprising bleaching kraft fibers with a multi-step bleaching process to produce bleached kraft fibers, wherein no additional bleaching occurs after the treating.

32. The process of claim 27, wherein the fluff pulp has a carboxyl content greater than 3.5 meq / 100 grams.

33. The process of claim 27, wherein the fluff pulp further includes iron ions.

34. The process of claim 33, wherein the fluff pulp includes an iron ion content of 0.2 ppm to 50 ppm by weight of the bleached kraft fibers.

35. The process of claim 27, comprising adding 1.0 ppm to 3.7 ppm of copper or a salt thereof to the bleached kraft fibers to produce the fluff pulp by weight of the bleached kraft fibers.

36. A process for making a fluff pulp, the process comprising: adding 1.0 ppm to 5.0 ppm of copper or a salt thereof to bleached kraft fibers to produce the fluff pulp by weight of the bleached kraft fibers; wherein the fluff pulp includes bleached kraft fibers, the bleached kraft fibers including: a length-weighted average fiber length of at least 2 mm; a copper number of less than 7; and an ISO brightness of at least 80; and a copper ion content of 1.0 ppm to 5.0 ppm by weight of the bleached kraft fibers. wherein the fluff pulp has at least 50% greater inhibition of ammonia formation compared to second bleached kraft fibers formed from the same process without copper, wherein the fluff pulp does not include a superabsorbent polymer.

37. The process of claim 36, wherein the copper or salt thereof consists of one or more of the following: The element copper Cu 0 copper (I) and copper (II) salts.

38. The process of claim 36, wherein the copper or salt thereof consists of: copper (I) chloride, copper (I) oxide, copper (I) sulfate, copper (II) carbonate, copper (II) chloride, copper (II) phosphate, copper (II) nitrate, copper (II) perchlorate, copper (II) phosphate, copper (II) sulfate, copper (II) tetrafluoroborate, copper (II) triflate, a hydrate thereof, or a combination of any two or more thereof.

39. The process of claim 36, further comprising bleaching kraft fibers with a multi-step bleaching process to produce bleached kraft fibers, wherein the treatment occurs after the bleaching.

40. The process of claim 36, further comprising bleaching kraft fibers with a multi-step bleaching process to produce bleached kraft fibers, wherein no additional bleaching occurs after the treatment.

41. The process of claim 36, wherein the fluff pulp has a carboxyl content greater than 3.5 meq / 100 grams.

42. The process of claim 36, wherein the fluff pulp further comprises iron ions.

43. The process of claim 42, wherein the fluff pulp comprises an iron ion content of 0.2 ppm to 50 ppm by weight of the bleached kraft fibers.

44. The process of claim 36, comprising adding 1.0 ppm to 3.7 ppm of copper or a salt thereof by weight of the bleached kraft fibers to treat the bleached kraft fibers to produce the fluff pulp.

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