Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
  • A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
  • A61L15/22—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons containing macromolecular materials
  • A61L15/28—Polysaccharides or their derivatives
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
  • A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
  • A61L15/40—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons containing ingredients of undetermined constitution or reaction products thereof, e.g. plant or animal extracts
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
  • A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
  • A61L15/42—Use of materials characterised by their function or physical properties
  • A61L15/60—Liquid-swellable gel-forming materials, e.g. super-absorbents

Definitions

• This disclosure relates to the chemical modification of cellulose fiber. More particularly, this disclosure relates to chemically modified cellulose fiber derived from bleached kraft pulp that exhibits a unique set of characteristics, improving its performance over standard cellulose fiber derived from kraft pulp and making it useful in applications that have heretofore been limited to expensive fibers (e.g., cotton or high alpha content sulfite pulp).
• the chemically modified bleached kraft fiber may exhibit one or more of the following beneficiai charactenstics, including but not limited to, improved odor control, improved compressibility, and/or improved brightness.
• the chemically modified bleached kraft fiber may exhibit one or more of these beneficial characteristics while also maintaining one or more other characteristics of the non-chemicaliy modified bleached kraft fiber, for example, maintaining fiber length and/or freeness.
• This disclosure further relates to chemically modified cellulose fiber derived from bleached softwood and/or hardwood kraft pulp that exhibits a low or ultra low degree of polymerization, making it suitable for use as fluff pulp in absorbent products, as a chemical cellulose feedstock in the production of cellulose derivatives including cellulose ethers and esters, and in consumer products.
• degree of polymerization may be abbreviated "DP.”
• This disclosure still further relates to cellulose derived from a chemically modified kraft fiber having a level-off degree of polymerization of 4 000854
• the chemically modified kraft fiber described herein, exhibiting a low or ultra low degree of polymerization can be treated by acid or alkaline hydrolysis to further reduce the degree of polymerization to less than about 80, for instance to less than about 50, to make it suitable for a variety of downstream applications.
• This disclosure also relates to methods for producing the improved fiber described.
• This disclosure provides, in part, a method for simultaneously increasing the carboxylic and aldehydic functionality of kraft fibers.
• the fiber, described is subjected to a catalytic oxidation treatment.
• the fiber is oxidized with iron or copper and then further bleached to provide a fiber with beneficial brightness characteristics, for example brightness comparable to standard bleached fiber.
• at least one process is disclosed that can provide the improved beneficial
• the fiber can be treated in a single stage of a kraft process, such as a kraft bleaching process.
• a five-stage bleaching process comprising a sequence of D 0 E1 D1 E2D2, where stage four (E2) comprises the catalytic oxidation treatment,
• this disclosure relates to consumer products, cellulose derivatives (including cellulose ethers and esters), and microcrystal!ine DCluiose all produced using the chemically modified cellulose fiber as described.
• Cellulose fiber and derivatives are widely used in paper, absorbent products, food or food-related applications, pharmaceuticals, and in industrial applications.
• the main sources of cellulose fiber are wood pulp and cotton.
• the cellulose source and the cellulose processing conditions generally dictate the cellulose fiber characteristics, and therefore, the fiber's applicability for certain end uses.
• Celiuiose exists generally as a polymer chain comprising hundreds to tens of thousands of glucose units.
• Various methods of oxidizing cellulose are known, n candiulose oxidation, hydroxy! groups of the glycosides of the DCiu!ose chains can be converted, for example, to carbonyl groups such as aldehyde groups or carboxyiic acid groups.
• carbonyl groups such as aldehyde groups or carboxyiic acid groups.
• the type, degree, and location of the carbonyl modifications may vary. It is known that, certain oxidation conditions may degrade the cellulose chains themselves, for example by cleaving the giycosidic rings in the cellulose chain, resulting in depoiymerization.
• depo!ymerized cellulose not only has a reduced viscosity, but also has a shorter fiber length than the starting DCiuSosic material.
• celiuiose is degraded, such as by depolymerizing and/or significantly reducing the fiber length and/or the fiber strength, it may be difficult to process and/or may be unsuitable for many downstream applications.
• a need remains for methods of modifying cellulose fiber that may improve both carboxyiic add and aldehyde functionalities, which methods do not extensively degrade the cellulose fiber. This disclosure provides unique methods that resolve one or more of these deficiencies.
• This disclosure provides novel methods that offer vast improvements over methods attempted in the prior art.
• oxidization of cellulose kraft fibers in the prior art, is conducted after the bleaching process.
• the inventors have discovered that it is possible to use the existing stages of a bleaching sequence, particularly the fourth stage of a five stage bleaching sequence, for oxidation of cellulose fibers.
• a metal catalyst particularly an iron catalyst, could be used in the bleaching sequence to accomplish this oxidation without interfering with the final product, for example, because the catalyst did not remain bound in the cellulose resulting in easier removal of at least some of the residual iron prior to the end of the bleaching sequence than would have been expected based upon the knowledge in the art.
• the inventors have discovered that such methods could be conducted without substantially degrading the fibers.
• cellulose fiber including kraft pulp
• metals and peroxides and/or peracids may be oxidized with metals and peroxides and/or peracids.
• cellulose may be oxidized with iron and peroxide ("Fenton's reagent").
• Fenton's reagent iron and peroxide
• Metals and peroxides, such as Fenton's reagent are relatively inexpensive oxidizing agents, making them somewhat desirable for large scale applications, such as kraft processes, in the case of Fenton's reagent, it is known that this oxidation method can degrade cellulose under acidic conditions.
• Fenton's reagent could be used in a kraft process without extensive degradation of the fibers, for example with an accompanying loss in fiber length, at acidic conditions.
• Fenton's reagent is often used under alkaline conditions, where the Fenton reaction is drastically inhibited.
• additional drawbacks may exist to using Fenton's reagent under alkaline conditions.
• the cellulose may nonetheless be degraded or discolored.
• the cellulose fiber is often bleached in multi-stage sequences, which traditionally comprise strongly acidic and strongly alkaline bleaching steps, including at least one alkaline step at or near the end of the bleaching sequence. Therefore, contrary to what was known in the art, it was quite surprising that fiber oxidized with iron in an acidic stage of a kraft bleaching process couid result in fiber with enhanced chemical properties, but without physical degradation or discoloration.
• the method of oxidation may affect other properties, including chemical and physical properties and/or impurities in the final products.
• the method of oxidation may affect the degree of crystailinity, the hemi-cellu!ose content, the color, and/or the levels of impurities in the final product.
• the method of oxidation may impact the ability to process the cellulose product for industrial or other applications.
• Bleaching of wood pulp is generally conducted with the aim of selectively increasing the whiteness or brightness of the pu!p, typically by removing iignin and other impurities, without negatively affecting physical properties.
• Bleaching of chemical pulps, such as kraft pulps generally requires several different bleaching stages to achieve a desired brightness with good selectivity.
• a bleaching sequence employs stages conducted at alternating pH ranges. This alternation aids in the removal of impurities generated in the bleaching sequence, for example, by solubiiizing the products of Iignin breakdown.
• a series of acidic stages in a bleaching sequence such as three acidic stages in P T/IB2014/000854
• acidic/alkaiine stages such as acidic-alkaline-acidic.
• a typical DEDED sequence produces a brighter product than a DEDAD sequence (where A refers to an acid treatment). Accordingly, a sequence that does not have an intervening alkaline stage, yet produces a product with comparable brightness, would not be expected by a person of skill in the art,
• the inventors have overcome these difficulties, and in some embodiments, provide a novel method of inexpensively oxidizing cellulose with iron or copper in a pufp bleaching processes.
• the methods disclosed herein result in products that have characteristics that are very surprising and contrary to those predicted based on the teachings of the prior art,
• the methods of the disclosure may provide products that are superior to the products of the prior art and can be more cost-effectively produced.
• metals such as iron
• removing iron from cellulose is difficult and costly, and requires additional processing steps.
• the presence of high levels of residual iron in a cellulose product is known to have several drawbacks, particularly in pulp and papermaking applications.
• iron may lead to discoloration of the final product and/or may be unsuitable for applications in which the final product is in contact with the skin, such as in diapers and wound dressings.
• the use of iron in a kraft bleaching process would be expected to suffer from a number of drawbacks.
• oxidation treatment of kraft fiber to improve functionality has often been limited to oxidation treatment after the fiber was bleached.
• known processes for rendering a fiber more aldehydic also cause a concomitant loss in fiber brightness or quality.
• known processes that result in enhanced aldehydic functionality of the fiber also result in a loss of carboxyiic functionality.
• the methods of this disclosure do not suffer from one or more of those drawbacks.
• Kraft fiber, produced by a chemical kraft pulping method provides an inexpensive source of cellulose fiber that generally maintains its fiber length through pulping, and generally provides final products with good brightness and strength characteristics. As such, it is widely used in paper applications.
• standard kraft fiber has limited applicability in downstream applications, such as cellulose derivative production, due to the chemical structure of the cellulose resulting from standard kraft pulping and bleaching.
• standard kraft fiber contains too much residual hemi- cellulose and other naturally occurring materials that may interfere with the subsequent physical and/or chemical modification of the fiber.
• standard kraft fiber has limited chemical functionality, and is generally rigid and not highly compressible.
• the rigid and coarse nature of kraft fiber can require the layering or addition of different types of materials, such as cotton, in applications that require contact with human skin, for example, diapers, hygiene products, and tissue products. Accordingly, it may be desirable to provide a cellulose fiber with better flexibility and/or softness to reduce the requirement of using other materials, for example, in a multi-layered product.
• Cellulose fiber in applications that involve absorption of bodily waste and/or fluids is often exposed to ammonia present in bodily waste and/or ammonia generated by bacteria associated with bodily waste and/or fluids. It may be desirable in such applications to use a cellulose fiber which not only provides bulk and absorbency, but which also has odor reducing and/or antibacterial properties, e.g., can reduce odor from nitrogenous compounds, such as ammonia (NH 3 ).
• a cellulose fiber which not only provides bulk and absorbency, but which also has odor reducing and/or antibacterial properties, e.g., can reduce odor from nitrogenous compounds, such as ammonia (NH 3 ).
• modification of kraft fiber by oxidation to improve its odor control capability invariably came with an undesirable decrease in brightness.
• Ultra-thin product designs require lower fiber weight and can suffer from a loss of product integrity if the fiber used is too short.
• Chemical modification of kraft fiber can result in loss of fiber length making it unacceptable for use in certain types of products, e.g., ultra-thin products.
• kraft fiber treated to improve aldehyde functionality which is associated with improved odor control, may suffer from a loss of fiber length during chemical modification making it unsuitable for use in ultra-thin product designs.
• cellulose sources that were useful in the production of absorbent products or tissue were not also useful in the production of downstream cellulose derivatives, such as cellulose ethers and cellulose esters.
• Cotton Sinter and high alpha cellulose content sulfite pulps which generally have a high degree of polymerization, are generally used in the manufacture of cellulose derivatives such as cellulose ethers and esters.
• Microcrysta!line cellulose is widely used in food, pharmaceutical, cosmetic, and industrial applications, and is a purified crystalline form of partially depolymerized cellulose.
• Microcrystalline cellulose production generally requires a highly purified ceSlulosic starting material, which is acid hydrolyzed to remove amorphous segments of the cellulose chain. See U.S. Patent No. 2,978,446 to Battista et al. and U.S. Patent No. 5,346,589 to Braunstein et al.
• a low degree of polymerization of the chains upon removal of the amorphous segments of cellulose is frequently a starting point for microcrystalline cellulose production and its numerical value depends primarily on the source and the processing of the cellulose fibers.
• the dissolution of the non-crystalline segments from standard kraft fiber generally degrades the fiber to an extent that renders it unsuitable for most applications because of at least one of 1) remaining impurities; 2) a lack of sufficiently long crystalline segments; or 3) it results in a cellulose fiber having too high a degree of polymerization, typically in the range of 200 to 400, to make it useful in the production of microcrystalline cellulose.
• fiber having one or more of the described properties can be produced simply through modification of a typical kraft pulping plus bleaching process.
• Fiber of the present disclosure overcomes many of the limitations associated with known modified kraft fiber discussed above.
• FIGURE 1 shows a chart of final 0.5% capillary CED viscosity as a function of percent peroxide consumed.
• FIGURE 2 shows a chart of wet strength to dry strength ratio given as a function of wet strength resin level.
• the disclosure provides novel methods for treating cellulose fiber.
• the disclosure provides a method of modifying cellulose fiber, comprising providing cellulose fiber, and oxidizing the celiuiose fiber.
• oxidized “catalytica!ly oxidized,” “catalytic oxidation” and “oxidation” are all understood to be interchangeable and refer to treatment of cellulose fiber with at least a catalytic amount of at least one of iron or copper and at least one peroxide, such as hydrogen peroxide, such that at least some of the hydroxy! groups of the cellulose fibers are oxidized.
• the phrase “iron or copper” and similarly “iron (or copper)” mean “iron or copper or a combination thereof.”
• the oxidation comprises simultaneously increasing carboxylic acid and aldehyde content of the celiuiose fiber.
• the cellulose fiber used in the methods described herein may be derived from softwood fiber, hardwood fiber, and mixtures thereof, in some embodiments, the modified cellulose fiber is derived from softwood, such as southern pine. In some embodiments, the modified cellulose fiber is derived from hardwood, such as eucalyptus. In some embodiments, the modified cellulose fiber is derived from a mixture of softwood and hardwood. In yet another embodiment, the modified cellulose fiber is derived from cellulose fiber that has previously been subjected to all or part of a kraft process, i.e., kraft fiber.
• the method comprises providing cellulose fiber, and oxidizing the cellulose fiber while generally maintaining the fiber length of the cellulose fibers
• a fiber having an average fiber length of 2 mm should be understood to mean a fiber having a length-weighted average fiber length of 2 mm.
• the method comprises providing cellulose fiber, partially bleaching the cellulose fiber, and oxidizing the cellulose fiber.
• the oxidation is conducted in the bleaching process. In some embodiments, the oxidation is conducted after the bleaching process.
• the method comprises providing the cellulose fiber, and oxidizing cellulose fiber thereby reducing the degree of polymerization of the cellulose fiber.
• the method comprises providing cellulose fiber, and oxidizing the cellulose fiber while maintaining the
• the method comprises providing cellulose fiber, oxidizing the cellulose fiber, and increasing the brightness of that oxidized cellulose fiber over standard cellulose fiber.
• oxidation of cellulose fiber involves treating the cellulose fiber with at least a catalytic amount of iron or copper and hydrogen peroxide.
• the method comprises oxidizing cellulose fiber with iron and hydrogen peroxide.
• the source of iron can be any suitable source, as a person of skill would recognize, such as for example ferrous sulfate (for example ferrous sulfate hepfahydrate), ferrous chloride, ferrous ammonium sulfate, ferric chloride, ferric ammonium sulfate, or ferric ammonium citrate.
• the method comprises oxidizing the cellulose fiber with copper and hydrogen peroxide.
• the source of copper can be any suitable source as a person of skill would recognize.
• the method comprises oxidizing the cellulose fiber with a combination of copper and iron and hydrogen peroxide.
• the disclosure provides a method for treating cellulose fiber, comprising, providing cellulose fiber, pulping the cellulose fiber, bleaching the cellulose fiber, and oxidizing the cellulose fiber.
• the method further comprises oxygen delignifying the cellulose fiber.
• Oxygen delignification can be performed by any method known to those of ordinary skill in the art.
• oxygen delignification may be a conventional two-stage oxygen delignification. It is known, for example, that oxygen delignifying cellulose fiber, such as Kraft fiber, may alter the carboxylic acid and/or aldehyde content of the cellulose fiber during processing.
• the method comprises oxygen delignifying the cellulose fiber before bleaching the cellulose fiber.
• the method comprises oxidizing cellulose fiber in at least one of a kraft pulping step, an oxygen delignification step, and a kraft bleaching step.
• the method comprises oxidizing the cellulose fiber in at least one kraft bleaching step, in at least one embodiment, the method comprises oxidizing the cellulose fiber in two or more than one kraft bleaching steps.
• the method comprises oxidizing cellulose fiber at an acidic pH.
• the method comprises providing cellulose fiber, acidifying the cellulose fiber, and then oxidizing the cellulose fiber at acidic pH.
• the pH ranges from about 2 to about 8, for example from about 2 to about 5 or from about 2 to about 4.
• the pH can be adjusted using any suitable acid, as a person of skill would recognize, for example, sulfuric acid or hydrochloric acid or filtrate from an acidic bleach stage of a bleaching process, such as a chlorine dioxide (D) stage of a multi-stage bleaching process.
• the cellulose fiber may be acidified by adding an extraneous acid. Examples of extraneous acids are known in the art and include, but are not limited to, sulfuric acid, hydrochloric acid, and carbonic acid.
• the cellulose fiber is acidified with acidic filtrate, such as waste filtrate, from a bleaching step.
• the acidic filtrate from a bleaching step does not have a high iron content.
• the cellulose fiber is acidified with acidic filtrate from a D stage of a multi-stage bleaching process.
• the method comprises oxidizing the cellulose fiber in one or more stages of a multi-stage bleaching sequence. In some embodiments, the method comprises oxidizing the cellulose fiber in a single stage of a multi-stage bleaching sequence. In some embodiments, the method comprises oxidizing the cellulose fiber at or near the end of a multistage bleaching sequence, !n some embodiments, the method comprises oxidizing cellulose fiber in at least the fourth stage of a five-stage bleaching sequence.
• the multi-stage bleaching sequence can be any bleaching sequence that does not comprise an alkaline bleaching step following the oxidation step, in at least one embodiment, the multi-stage bleaching sequence is a five-stage bleaching sequence.
• the bleaching sequence is a DEDED sequence.
• the bleaching sequence is a D C E1 D1 E2D2 sequence, in some embodiments, the bleaching sequence is a D 0 (EoP)D1 E2D2 sequence, in some embodiments the bleaching sequence is a D 0 (EO)D1 E2D2.
• non-oxidation stages of a multi-stage bleaching sequence may include any convention or after discovered series of stages, be conducted under conventional conditions, with the proviso that to be useful in producing the modified fiber described in the present disclosure, no alkaline bleaching step may follow the oxidation step,
• the oxidation is incorporated into the fourth stage of a multi-stage bleaching process, in some embodiments, the method is implemented in a five-stage bleaching process having a sequence of D 0 E1 D1 E2D2, and the fourth stage (E2) is used for oxidizing kraft fiber.
• the kappa number increases after oxidation of the ceilulose fiber. More specifically, one would typically expect a decrease in kappa number across this bleaching stage based upon the anticipated decrease in materia!, such as iignin, which reacts with the permanganate reagent.
• the kappa number of cellulose fiber may decrease because of the loss of impurities, e.g., Iignin; however, the kappa number may increase because of the chemical modification of the fiber.
• the increased functionality of the modified cellulose provides additional sites that can react with the permanganate reagent. Accordingly, the kappa number of modified kraft fiber is elevated relative to the kappa number of standard kraft fiber.
• the oxidation occurs in a single stage of a bleaching sequence after both the iron or copper and peroxide have been added and some retention time provided.
• An appropriate retention is an amount of time that is sufficient to catalyze the hydrogen peroxide with the iron or copper. Such time will be easily ascertainable by a person of ordinary skill in the art.
• the oxidation is carried out for a time and at a temperature that is sufficient to produce the desired completion of the reaction.
• the oxidation may be carried out at a temperature ranging from about 60 to about 80 degrees C, and for a time ranging from about 40 to about 80 minutes. The desired time and
• the cellulose fiber is digested to a target kappa number before bleaching.
• the cellulose fiber may be digested in a two-vessel hydraulic digester with Lo-SolidsTM cooking to a kappa number ranging from about 30 to about 32 before bleaching and oxidizing the cellulose.
• oxidized cellulose is desired for cellulose derivative applications, for instance in the manufacture of cellulose ethers, cellulose fiber may be digested to a kappa number ranging from about 20 to about 24 before bleaching and oxidizing the cellulose according to the methods of this disclosure.
• the cellulose fiber is digested and delignified in a conventional two-stage oxygen delignification step before bleaching and oxidizing the cellulose fiber.
• the delignification is carried out to a target kappa number ranging from about 6 to about 8 when the oxidized cellulose is intended for cellulose derivative applications, and a target kappa number ranging from about 12 to about 14 when the oxidized cellulose is intended for paper and/or fluff applications.
• the bleaching process is conducted under conditions to target about 88-90% final ISO brightness, such as ranging from about 85 to about 95%, or from about 88% to about 90%.
• the disclosure also provides a method of treating cellulose fiber, comprising providing cellulose fiber, reducing the DP of the cellulose fiber, and maintaining the fiber length of the cellulose fiber.
• the cellulose fiber is kraft fiber.
• the DP of the cellulose fiber is reduced in a bleaching process.
• the DP of the cellulose fiber is reduced at or near the end of a multi-stage bleaching sequence.
• the DP is reduced in at least the fourth stage of a multi-stage bleaching sequence.
• the DP is reduced in or after the fourth stage of a multi-stage bleaching sequence.
• the multi-stage bleaching sequence may be altered to provide more robust bleaching conditions prior to oxidizing the cellulose fiber.
• the method comprises providing more robust bleaching conditions prior to the oxidation step. More robust bleaching conditions may allow the degree of polymerization and/or viscosity of the cellulose fiber to be reduced in the oxidation step with lesser amounts of iron or copper and/or hydrogen peroxide. Thus, it may be possible to modify the bleaching sequence conditions so that the brightness and/or viscosity of the final cellulose product can be further controlled.
• reducing the amounts of peroxide and metal while providing more robust bleaching conditions before oxidation, may provide a product with lower viscosity and higher brightness than an oxidized product produced with identical oxidation conditions but with less robust bleaching.
• Such conditions may be
• the methods of the disclosure further comprise reducing the crystallinity of cellulose fiber so that it is lower than the crystaliinity of that cellulose fiber as measured before the oxidation stage.
• the crystallinity index of the cellulose fiber may be reduced up to 20% relative to the starting crystallinity index as measured before the oxidation stage.
• the methods of the disclosure further comprise treating the modified cellulose fiber with at least one caustic or alkaline substance.
• a method of treating cellulose fiber comprises providing an oxidized cellulose fiber of the disclosure, exposing the oxidized cellulose fiber to an alkaline or caustic substance, and then dry laying the cellulose product.
• at least one caustic substance to the modified cellulose may result in a cellulose fiber having very high functionality and very low fiber length.
• the disclosure provides a method for improving the wet strength of a product, comprising providing modified cellulose fiber of the disclosure and adding the modified cellulose fiber of the disclosure to a product, such as a paper product.
• the method may comprise oxidizing cellulose fiber in a bleaching process, further treating the oxidized cellulose fiber with an acidic or caustic substance, and adding the treated fiber to a cellulose product.
• hydrogen peroxide is added to the cellulose fiber in acidic media in an amount sufficient to achieve the desired oxidation and/or degree of polymerization and/or viscosity of the final cellulose product.
• peroxide can be added in an amount of from about 0,1 to about 4%, or from about 1% to about 3%, or from about 1% to about 2%, or from about 2% to about 3%, based on the dry weight of the pulp.
• Iron or copper are added at least in an amount sufficient to catalyze the oxidation of the cellulose with peroxide.
• iron can be added in an amount ranging from about 25 to about 200 ppm based on the dry weight of the kraft pulp.
• a person of skill in the art will be able to readily optimize the amount of iron or copper to achieve the desired level or amount of oxidation and/or degree of polymerization and/or viscosity of the final cellulose product.
• the method further involves adding steam either before or after the addition of hydrogen peroxide.
• the final DP and/or viscosity of the pulp can be controlled by the amount of iron or copper and hydrogen peroxide and the robustness of the bleaching conditions prior to the oxidation step.
• a person of skill in the art will recognize that other properties of the modified kraft fiber of the disclosure may be affected by the amounts of iron or copper and hydrogen peroxide and the robustness of the bleaching conditions prior to the oxidation step.
• a person of skill in the art may adjust the amounts of iron or copper and hydrogen peroxide and the robustness of the bleaching conditions prior to the oxidation step to target or achieve a desired brightness in the final product and/or a desired degree of polymerization or viscosity.
• the disclosure provides a method of modifying cellulose fiber, comprising providing cellulose fiber, reducing the degree of polymerization of the cellulose fiber, and maintaining the fiber length of the cellulose fiber.
• the oxidized kraft fiber of the disclosure is not refined. Refining of the oxidized kraft fiber may have a negative impact on its fiber length and integrity, for instance refining the fiber may cause the fiber to fail apart.
• each stage of the five-stage bleaching process includes at least a mixer, a reactor, and a washer (as is known to those of skill in the art).
• a kraft pulp is acidified on a D1 stage washer, the iron source is also added to the kraft pulp on the D1 stage washer, the peroxide is added foliowing the iron source (or copper source) at an addition point in the mixer or pump before the E2 stage tower, the kraft pulp is reacted in the E2 tower and washed on the E2 washer, and steam may optionally be added before the E2 tower in a steam mixer.
• iron (or copper) can be added up until the end of the D1 stage, or the iron (or copper) can also be added at the beginning of the E2 stage, provided that the pulp is acidified first (i.e., prior to addition of the iron) at the D1 stage. Steam may be optionally added either before or after the addition of the peroxide.
• the method for preparing a low viscosity modified cellulose fiber may involve bleaching kraft pulp in a multistage bleaching process and reducing the DP of the pulp at or near a final stage of the multi-stage bleaching process (for example in the 4th stage of a multi-stage bleaching process, for example in the 4th stage of a 5 stage bleaching process) using a treatment with hydrogen peroxide in an acidic media and in the presence of iron.
• the final DP of the pulp may be controlled by the appropriate application of the iron or copper and hydrogen peroxide, as further described in the Examples section.
• the iron or copper and hydrogen peroxide is provided in amounts and under conditions appropriate for producing a low DP fiber (i.e., a fiber having a DPw ranging from about 1 180 to about 1830, or a 0.5%
• the iron or copper and hydrogen peroxide may be provided in amounts and under conditions appropriate for producing an ultra low DP fiber (i.e., a fiber having a DPw ranging from about 700 to about 1180, or a 0.5% 0.5% Capillary CED viscosity ranging from about 3.0 to about 7 mPa*s).
• the treatment with hydrogen peroxide in an acidic media with iron or copper may involve adjusting the pH of the kraft pulp to a pH ranging from about 2 to about 5, adding a source of iron to the acidified pulp, and adding hydrogen peroxide to the kraft pulp.
• the method of preparing a modified cellulose fiber within the scope of the disclosure may involve acidifying the kraft pulp to a pH ranging from about 2 to about 5 (using for example sulfuric acid), mixing a source of iron (for example ferrous sulfate, for example ferrous sulfate heptahydrate) with the acidified kraft pulp at an application of from about 25 to about 250 ppm Fe ⁇ z based on the dry weight of the kraft memep at a consistency ranging from about 1 % to about 15% and also hydrogen peroxide, which can be added as a solution at a concentration of from about 1 % to about 50% by weight and in an amount ranging from about 0.1 % to about 1.5% based on the dry weight of the kraft pulp, in some embodiments, the ferrous sulfate solution is mixed with the kraft pulp at a consistency ranging from about 7% to about 15%.
• the acidic kraft pulp is mixed with the iron source and reacted with
• the method of preparing a modified cellulose fiber within the scope of this disclosure involves reducing DP by treating a kraft pulp with hydrogen peroxide in an acidic media in the presence of iron (or copper), wherein the acidic, hydrogen peroxide and iron (or copper) treatment is incorporated into a multi-stage bleaching process.
• the treatment with iron, acid and hydrogen peroxide is incorporated into a single stage of the multi-stage bleaching process.
• the treatment with iron (or copper), acid and hydrogen peroxide is incorporated into a single stage that is at or near the end of the multi-stage bleaching process.
• the treatment with iron (or copper), acid and hydrogen peroxide is incorporated into the fourth stage of a multi-stage bleaching process.
• the pulp treatment may occur in a single stage, such as the E2 stage, after both the iron (or copper) and peroxide have been added and some retention time provided.
• each stage of a five stage bleaching process includes at least a mixer, a reactor, and a washer (as is known to those of skill in the art), and the kraft pulp may be acidified on the D1 stage washer, the iron source may aiso be added to the kraft memep on the D1 stage washer, the peroxide may be added following the iron source (or copper source) at an addition point in the mixer or pump before the E2 stage tower, the kraft pulp may be reacted in the E2 tower and washed on the E2 washer, and steam may optionally be added before the E2 tower in a steam mixer, !n some embodiments, for example, iron (or copper) can be added up until the end of the D1 stage, or the iron (or copper) could also be added at the beginning of the E2 stage, provided that the pulp is acidified first (i.e., prior to addition of the iron) at the D1 stage, extra acid may be added if needed to bring the pH into the range of from about 3 to about 5, and per
• the above-described five stage bleaching processes conducted with a softwood cellulose starting material may produce modified cellulose fiber having one or more of the following properties: an average fiber length of at least 2.2 mm, a viscosity ranging from about 3.0 mPa » s to less than 13 mPa « s, an S10 caustic soiubiiity ranging from about 16% to about 20%, an S18 caustic solubility ranging from about 14% to about 18%, a carboxyi content ranging from about 2 meq/100 g to about 6 meq/100 g, an aldehyde content ranging from about 1 meq/100 g to about 3 meq/100 g, a carbonyl content of from about 1 to 4, a freeness ranging from about 700 mis to about 760 mis, a fiber strength ranging from about 5 km to about 8 km, and a brightness ranging from about 85 to about 95 ISO.
• the above-described exemplary five stage bleaching processes may produce a modified cellulose softwood fiber having an average fiber length that is at least 2.0 mm (for example ranging from about 2.0 mm to about 3.7 mm, or from about 2.2 mm to about 3.7 mm), a viscosity that is less than 13 mPa-s (for example a viscosity ranging from about 3.0 mPa*s to less than 13 mPa » s, or from about 3.0 mPa » s to about 5.5 mPa s s, or from about 3.0 mPa » s to about 7 mPa » s, or from about 7 mPa s s to less than 13 mPa » s ), and a brightness of at least 85 (for example ranging from about 85 to about 95).
• a viscosity that is less than 13 mPa-s for example a viscosity ranging from about 3.0 mPa*s to less than 13 mP
• the disclosure provides a method for producing fluff pulp, comprising providing modified kraft fiber of the disclosure and then producing a fluff pulp.
• the method comprises bleaching kraft fiber in a multi-stage bleaching process, oxidizing the fiber in at least the fourth or fifth stage of the multi-stage bleaching process with hydrogen peroxide under acidic conditions and a catalytic amount of iron or copper, and then forming a fluff pulp.
• the fiber is not refined after the multi-stage bleaching process.
• the disclosure also provides a method for reducing odor, such as odor from bodily waste, for example odor from urine or blood.
• the disclosure provides a method for controlling odor, comprising providing a modified bleached kraft fiber according to the disclosure, and applying an odorant to the bleached kraft fiber such that the atmospheric amount of odorant is reduced in comparison with the
• the disclosure provides a method for controlling odor comprising inhibiting bacterial odor generation. In some embodiments, the disclosure provides a method for controlling odor comprising absorbing odorants, such as nitrogenous odorants, onto a modified kraft fiber.
• odorants such as nitrogenous odorants
• nitrogenous odorants Is understood to mean odorants comprising at least one nitrogen.
• a method of reducing odor comprises providing modified cellulose fiber according to the disclosure, and applying an odorant such as a nitrogenous compound, for instance ammonia, or an organism that is capabie of generating a nitrogenous compound to the modified kraft fiber.
• the method further comprises forming a fluff pulp from modified cellulose fiber before adding an odorant to the modified kraft fiber.
• the odorant comprises at least one bacteria capable of producing nitrogenous compounds.
• the odorant comprises nitrogenous compounds, such as ammonia.
• the method of reducing odor further comprises absorbing ammonia onto modified cellulose fiber, in some embodiments, the method of reducing odor further comprises inhibiting bacterial ammonia production. In some embodiments, the method of inhibiting bacterial ammonia production comprises inhibiting bacterial growth. In some embodiments, the method of inhibiting bacterial ammonia production comprises inhibiting bacterial urea synthesis.
• a method of reducing odor comprises combining modified cellulose fiber with at least one other odor reductant, and then applying an odorant to the modified cellulose fiber combined with odor reductant.
• odor reductants include, for example, odor reducing agents, odor masking agents, biocides, enzymes, and urease inhibitors.
• modified cellulose fiber may be combined with at least one odor reductant chosen from zeolites, activated carbons, diatomaceous earth, cyc!odextrins, clay, chelating agents, such as those containing metal ions, such as copper, silver or zinc sons, ion exchange resins, antibacterial or antimicrobial polymers, and/or aromatizers.
• the modified cellulose fiber is combined with at least one super absorbent polymer (SAP).
• SAP may by an odor reductant.
• Examples of SAP that can be used in accordance with the disclosure include, but are not limited to, HysorbTM sold by the company BASF, Aqua Keep® sold by the company Sumitomo, and FAVOR ⁇ , sold by the company Evonik. II. Kraft Fibers
• the present disclosure provides kraft fiber with low and ultra-low viscosity.
• viscosity refers to 0.5% Capillary CED viscosity measured according to TAPPi T230 ⁇ om99 as referenced in the protocols.
• Modified kraft fiber of the present invention exhibits unique characteristics which are indicative of the chemical
• fiber of the present invention exhibits characteristics similar to those of standard kraft fiber, i.e., length and freeness, but also exhibits some very different characteristics which are a function of the increased number of functional groups that are included in the modified fiber.
• This modified fiber exhibits unique
• the cited TAPPS test treats fiber with a caustic agent as part of the test method.
• the application of caustic to the modified fiber, as described, causes the modified fiber to hydrolyze differently than standard kraft fiber thus reporting a viscosity which is generally lower than the viscosity of standard kraft fiber.
• the reported viscosities may be affected by the viscosity measurement method.
• the viscosities reported herein as measured by the cited TAPPI method represent the viscosity of the kraft fiber used to calculate the degree of polymerization of the fiber.
• DP refers to average degree of polymerization by weight (DPw) calculated from 0.5% Capillary CED viscosity measured according to TAPPi T230-om99. See, e.g. ⁇ J.F. Ceilucon Conference in The Chemistry and Processing of Wood and Piant Fibrous Materials, p. 155, test protocol 8, 1994 (Woodhead Publishing Ltd., Abington Hall, Abinton Cambridge CBI 6AH England, J.F. Kennedy et al. eds.) "Low DP” means a DP ranging from about 1 180 to about 1880 or a viscosity ranging from about 7 to about 13 mPa*s. "Ultra low DP" fibers means a DP ranging from about 350 to about 1 180 or a viscosity ranging from about 3 to about 7 mPa*s.
• the fiber of the present invention presents an artificial Degree of Polymerization when DP is calculated via CED viscosity measured according to TAPPi T230- om99.
• the catalytic oxidation treatment of the fiber of the present invention does not break the cellulose down to the extent indicated by the measured DP, but instead largely has the effect of opening up bonds and adding substituents that make the cellulose more reactive, instead of cleaving the cellulose chain.
• modified cellulose fiber has a DP ranging from about 350 to about 1860. In some embodiments, the DP ranges from about 710 to about 1880. in some embodiments, the DP ranges from about 350 to about 910. In some embodiments, the DP ranges from about 350 to about 1 160. In some embodiments, the DP ranges from about 1 180 to about 1860. In some embodiments, the DP is less than 1860, less than 1550, less than 1300, iess than 820, or less than 600,
• modified cellulose fiber has a viscosity ranging from about 3.0 mPa « s to about 13 mPa « s. In some embodiments, the viscosity ranges from about 4.5 mPa-s to about 13 mPa*s, in some embodiments, the viscosity ranges from about 3.0 mPa » s to about 5.5 mPa ⁇ s, In some embodiments, the viscosity ranges from about 3.0 mPa*s to about 7 mPa*s. in some embodiments, the viscosity ranges from about 7 m a » s to about 13 mPa*s.
• the viscosity is less than 13 mPa » s, less than 10 mPa « s, less than 8 mPa*s, less than 5 mPa s s, or iess than 4 mPa*s.
• the modified kraft fiber of the disclosure maintains its freeness during the bleaching process.
• the modified cellulose fiber has a "freeness" of at ieast about 690 mis, such as at Ieast about 700 mis, or about 710 mis, or about 720 mis, or about 730 mis,
• modified kraft fiber of the disclosure maintains its fiber length during the bleaching process.
• the modified cellulose fiber when the modified cellulose fiber is a softwood fiber, the modified cellulose fiber has an average fiber length, as measured in accordance with Test Protocol 12, described in the Example section below, thai is about 2 mm or greater. In some embodiments, the average fiber length is no more than about 3.7 mm. In some embodiments, the average fiber length is at Ieast 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, or about 3.7 mm. !n some embodiments, the average fiber length ranges from about 2 mm to about 3.7 mm, or from about 2,2 mm to about 3.7 mm.
• modified cellulose fiber when the modified cellulose fiber is a hardwood fiber, the modified cellulose fiber has an average fiber length from about 0.75 to about 1.25 mm.
• the average fiber length may be at Ieast about 0.85 mm, such as about 0.95 mm, or about 1.05 mm, or about 1.15 mm.
• modified kraft fiber of the disclosure has a brightness equivalent to kraft fiber standard kraft fiber.
• the modified cellulose fiber has a brightness of at least 85, 86, 87, 88, 89, or 90 ISO. In some embodiments, the brightness is no more than about 92. In some embodiments, the brightness ranges from about 85 to about 92, or from about 86 to about 90, or from about 87 to about 90, or from about 88 to about 90.
• modified cellulose fiber of the disclosure is more compressible and/or embossable than standard kraft fiber.
• modified cellulose fiber may be used to produce structures that are thinner and/or have higher density than structures produced with equivalent amounts of standard kraft fiber.
• modified cellulose fiber of the disclosure may be compressed to a density of at least about 0.21 g/cc, for example about 0.22 g/cc, or about 0,23 g/cc, or about 0.24 g/cc. In some
• modified cellulose fiber of the disclosure may be compressed to a density ranging from about 0.21 to about 0.24 g/cc. In at least one embodiment, modified cellulose fiber of the disclosure, upon compression at 20 psi gauge pressure, has a density ranging from about 0.21 to about 0.24 g/cc.
• modified cellulose fiber of the disclosure upon compression under a gauge pressure of about 5 psi, has a density ranging from about 0.1 10 to about 0.1 14 g/cc.
• modified cellulose fiber of the disclosure upon compression under a gauge pressure of about 5 psi, may have a density of at least about 0.110 g/cc, for example at least about 0.112 g/cc, or about 0.113 g/cc, or about 0.114 g/cc.
• modified cellulose fiber of the disclosure upon compression under a gauge pressure of about 10 psi, has a density ranging from about 0.130 to about 0. 55 g/cc.
• the modified cellulose fiber of the disclosure upon compression under a gauge pressure of about 10 psi, may have a density of at least about 0.130 g/cc, for example at least about 0.135 g/cc, or about 0.140 g/cc, or about 0.145 g/cc, or about 0.150 g/cc.
• modified candiu!ose fiber of the disclosure can be compressed to a density of at least about 8% higher than the density of standard kraft fiber.
• the modified celiuiose fiber of the disclosure have a density of about 8% to about 16% higher than the density of standard kraft fiber, for example from about 10% to about 16% higher, or from about 12% to about 16% higher, or from about 13% to about 16% higher, or from about 14% to about 16% higher, or from about 15% to about 16% higher.
• modified kraft fiber of the disciosure has increased carboxyl content relative to standard kraft fiber.
• modified cellulose fiber has a carboxyf content ranging from about 2 meq/100 g to about 9 meq/100 g. In some embodiments, the carboxyl content ranges from about 3 meq/100 g to about 8 meq/100 g. In some embodiments, the carboxyl content is about 4 meq/100 g.
• the carboxyl content is at least about 2 meq/100 g, for exampfe, at least about 2.5 meq/100 g, for example, at least about 3.0 meq/100 g, for example, at least about 3.5 meq/100 g, for example, at least about 4.0 meq/100 g, for example, at least about 4.5 meq/100 g, or for example, at least about 5.0 meq/100 g.
• Modified kraft fiber of the disciosure has increased aldehyde content relative to standard bleached kraft fiber.
• the modified kraft fiber has an aldehyde content ranging from about 1 meq/100 g to about 9 meq/100 g.
• the aldehyde content is at least about 1.5 meq/100 g, about 2 meq/100 g, about 2.5 meq/100 g, about 3.0 meq/100 g, about 3.5 meq/100 g, about 4.0 meq/100 g, about 4.5 meq/100 g, or about 5.0 meq/100 g, or at least about 6.5 meq, or at least about 7.0 meq.
• the modified cellulose fiber has a ratio of total aldehyde to carboxyl content of greater than about 0.3, such as greater than about 0.5, such as greater than about 1 , such as greater than about 1.4.
• the aldehyde to carboxyl ratio ranges from about 0.3 to about 1.5. In some embodiments, the ratio ranges from about 0.3 to about 0.5. In some embodiments, the ratio ranges from about 0.5 to about 1. In some embodiments, the ratio ranges from about 1 to about 1.5.
• modified kraft fiber has higher kink and curl than standard kraft fiber.
• Modified kraft fiber according to the present invention has a kink index in the range of about 1.3 to about 2.3.
• the kink index may range from about 1.5 to about 2.3, or from about 1.7 to about 2.3 or from about 1.8 to about 2.3, or from about 2,0 to about 2.3
• Modified kraft fiber according to the present disclosure may have a length weighted curl index in the range of about 0,1 1 to about 0.23, such as from about 0.15 to about 0.2.
• the crystaliinity index of modified kraft fiber is reduced from about 5% to about 20% relative to the crystaliinity index of standard kraft fiber, for instance from about 10% to about 20%, or from about 15% to about 20%.
• modified cellulose according to the present disclosure has an R 0 value ranging from about 65% to about 85%, for instance from about 70% to about 85%, or from about 75% to about 85%.
• modified fiber according to the disclosure has an R18 value ranging from about 75% to about 90%, for instance from about 80% to about 90%, for example from about 80% to about 87%.
• the R18 and R10 content is described in TAPPI 235.
• R10 represents the residual undissolved material that is left extraction of the pulp with 10 percent by weight caustic and R18 represents the residual amount of undissolved material left after extraction of the pulp with an 8% caustic solution.
• hemiceSlulose and chemically degraded short chain cellulose are dissolved and removed in solution. In contrast, generally only
• modified kraft fiber of the disclosure may have certain characteristics that standard kraft fiber does not possess. For instance, it is believed that kraft fiber of the disclosure may be more flexible than standard kraft fiber, and may elongate and/or bend and/or exhibit elasticity and/or increase wicking. Moreover, without being bound by theory, it is expected that modified kraft fiber may provide a physicai structure, for example in a fluff pulp, that would either cause fiber
• modified kraft fiber of the disclosure would be softer than standard kraft fiber, enhancing their applicability in absorbent product applications, for example, such as diaper and bandage applications.
• modified cellulose fiber has an S10 caustic solubility ranging from about 18% to about 30%, or from about 14% to about 16%. In some embodiments, modified cellulose fiber has an S18 caustic solubility ranging from about 14% to about 22%, or from about 14% to about 16%. In some embodiments, modified cellulose fiber has a AR
• the AR is about 6.0 or greater.
• modified cellulose fiber strength as measured by wet zero span breaking length, ranges from about 4 km to about 10 km, for instance, from about 5 km to about 8 km. In some embodiments, the fiber strength is at least about 4 km, about 5 km, about 6 km, about 7 km, or about 8 km. In some embodiments, the fiber strength ranges from about 5 km to about 7 km, or from about 6 km to about 7 km.
• modified kraft fiber has odor control properties.
• modified kraft fiber is capable of reducing the odor of bodily waste, such as urine or menses.
• modified kraft fiber absorbs ammonia, in some embodiments, modified kraft fiber inhibits bacterial odor production, for example, in some embodiments, modified kraft fiber inhibits bacterial ammonia production.
• modified kraft fiber is capable of absorbing odorants, such as nitrogen containing odorants, for example ammonia.
• odorant is understood to mean a chemical material that has a smell or odor, or that is capable of interacting with olfactory receptors, or to mean an organism, such as a bacteria, that is capable of generating compounds that generate a smell or odor, for example a bacteria that produces urea.
• modified kraft fiber reduces atmospheric ammonia concentration more than a standard bleached kraft fiber reduces atmospheric ammonia.
• modified kraft fiber may reduce atmospheric ammonia by absorbing at least part of an ammonia sample applied to modified kraft fiber, or by inhibiting bacterial ammonia production, in at least one embodiment, modified kraft fiber absorbs ammonia and inhibits bacterial ammonia production,
• modified kraft fiber reduces at least about 40% more atmospheric ammonia than standard kraft fibers, for example at least about 50% more, or about 60% more, or about 70% more, or about 75% more, or about 80% more, or about 90% more ammonia than standard kraft fiber.
• modified kraft fiber of the disclosure after application of 0.12 g of a 50% solution of ammonium hydroxide to about nine grams of modified cellulose and a 45 minute incubation time, reduces atmospheric ammonia concentration in a volume of 1.6 L to less than 150 ppm, for example, less than about 125 ppm, for example less than bout 100 ppm, for example, less than about 75 ppm, for example, less than about 50 ppm.
• modified kraft fiber absorbs from about 5 to about 10 ppm ammonia per gram of fiber.
• the modified cellulose may absorb from about 6 to about 10 ppm, or from about 7 to about 10 ppm, or from about 8 to about 10 ppm ammonia per gram of fibers.
• modified kraft fiber has both improved odor control properties and improved brightness compared to standard kraft fiber, in at least one embodiment, modified cellulose fiber has a brightness ranging from about 85 to about 92 and is capable of reducing odor.
• the modified cellulose may have a brightness ranging from about 85 to about 92, and absorbs from about 5 to about 10 ppm ammonia for every gram of fiber.
• modified cellulose fiber has an MEM E!ution Cytotoxicity Test, ISO 10993-5, of less than 2 on a zero to four scale.
• cytotoxicity may be less than about 1.5 or less than about 1.
• oxidized cellulose in particular cellulose comprising aldehyde and/or carboxyiic acid groups, exhibits anti-viral and/or antimicrobial activity. See, e.g., Song et al., Novel antiviral activity of diaidehyde starch, Electronic J. Biotech., Vol. 12, No. 2, 2009; U.S. Patent No. 7,019,191 to Looney et al.
• aldehyde groups in diaidehyde starch are known to provide antiviral activity
• oxidized cellulose and oxidized regenerated cellulose, for instance containing carboxyiic acid groups have frequently been used in wound care applications in part because of their bactericidal and hemostatic properties.
• the cellulose fibers of the disclosure may exhibit antiviral and/or antimicrobial activity.
• modified cellulose fiber exhibits antibacterial activity.
• modified cellulose fiber exhibits antiviral activity.
• modified kraft fiber of the disclosure has a level-off DP of less than 200, such as less than about 100, or less than about 80, or less than about 75, or less than about 50 or less than or equal to about 48, Level-off DP can be measured by methods known in the art, for example by methods disclosed in Battista, et al., Level-Off Degree of
• modified kraft fiber has a kappa number of less than about 2.
• modified kraft fiber may have a kappa number less than about 1.9.
• modified kraft fiber has a kappa number ranging from about 0.1 to about 1 , such as from about 0.1 to about 0.9, such as from about 0.1 to about 0.8, for example from about 0.1 to about 0.7, for instance from about 0.1 to about 0.6, such as from about 0.1 to about 0.5, or from about 0.2 to about 0.5.
• modified kraft fiber is kraft fiber bleached in a multi-stage process, wherein an oxidation step is followed by at least one bleaching step.
• the modified fiber after the at least one bleaching step has a "k number", as measured according to TAPPI U 251 , ranging from about 0.2 to about 1.2.
• the k number may range from about 0.4 to about 1.2, or from about 0.6 to about 1.2, or from about 0.8 to about 1.2, or from about 1.0 to about 1.2.
• the modified cellulose fiber has a copper number greater than about 2. in some embodiments, the copper number is greater than 2.0, In some embodiments, the copper number is greater than about 2.5. For example, the copper number may be greater than about 3. in some embodiments, the copper number ranges from about 2.5 to about 5.5, such as from about 3 to about 5.5, for instance from about 3 to about 5.2.
• the hemicei!ulose content of the modified kraft fiber is substantially the same as standard unbleached kraft fiber.
• the hemiceliulose content for a softwood kraft fiber may range from about 16% to about 18%,
• the hemiceliulose content of a hardwood kraft fiber may range from about 18% to about 25%.
• modified kraft fiber of the disclosure is suitable for production of cellulose derivatives, for example for production of lower viscosity cellulose ethers, cellulose esters, and microcrystal!ine cellulose.
• modified kraft fiber of the disclosure is hydrolyzed modified kraft fiber.
• hydrolyzed modified kraft fiber As used herein "hydrolyzed modified kraft fiber,” hydrolyzed kraft fiber” and the like are understood to mean fiber that has been hydrolyzed with any acid or alkaline treatment know to depolymerized the cellulose chain, !n some embodiments, the kraft fiber according to the disclosure is further treated to reduce its viscosity and/or degree of polymerization.
• the kraft fiber according to the disclosure may be treated with an acid or a base.
• the disclosure provides a method of treating kraft fiber, comprising bleaching kraft fiber according to the disclosure, and then hydroiyzing the bleached kraft fiber. Hydrolysis can be by any method known to those of ordinary skill in the art.
• the bleached kraft fiber is hydroiyzed with at least one acid.
• the bleached kraft fiber is hydroiyzed with an acid chosen from sulfuric acid, mineral acids, and hydrochloric acid
• the disclosure also provides a method for producing cellulose ethers.
• the method for producing cellulose ethers comprises bleaching kraft fiber in accordance with the disclosure, treating the bleached kraft fiber with at least one alkali agent, such as sodium hydroxide and reacting the fibers with at least one efherying agent.
• the disclosure also provides methods for producing cellulose esters.
• the method for producing cellulose esters comprises bleaching kraft fiber in accordance with the disclosure, treating the bleached kraft fiber with a catalyst, such as sulfuric acid, then treating the fiber with at least one acetic anhydride or acetic acid.
• the method for producing cellulose acetates comprises bleaching kraft fiber in accordance with the disclosure, hydroiyzing the bleached kraft fiber with sulfuric acid, and treating the hydroiyzed kraft fiber with at least one acetic anhydride or acetic acid.
• the disclosure also provides methods for producing
• the method for producing microcrystalline cellulose comprises providing bleached kraft fiber according to the disclosure, hydroiyzing the bleached kraft fiber with at least one acid until the desired DP is reached or under conditions to arrive at the level-off DP.
• the hydroiyzed bleached kraft fiber is mechanically treated, for example by grinding, milling, or shearing. Methods for mechanically treating hydrolyzed kraft fibers in microcrystalline cellulose production are known to persons of skill in the art, and may provide desired particle sizes. Other parameters and conditions for producing microcrystalline cellulose are known, and are described for example in U.S. Patent Nos.
• modified kraft fiber according to the disclosure is further treated with an alkaline agent or caustic agent to reduce its viscosity and/or degree of polymerization.
• Alkaline treatment a pH above about 9, causes dialdehydes to react and undergo a beta-hydroxy elimination.
• This further modified fiber that has been treated with an alkaline agent may also be useful in the production of tissue, towel and also other absorbent products and in cellulose derivative applications.
• strength agents are often added to the fiber slurry to modify the physical properties of the end products.
• This alkaline modified fiber may be used to replace some or all of the strength adjusting agent used in the production of tissue and towel.
• the first type is fiber that has been treated by catalytic oxidation, which fiber is almost indistinguishable from its conventional counterpart (at least as far as physical and papermaking properties are concerned), yet it has functionality associated with it that gives it one or more of its odor control properties, compressibility, low and ultra low DP, and/ or the ability to convert "in-situ" into a low DP/iow viscosity fiber under either alkaline or acid hydrolysis conditions, such as the conditions of cellulose derivative production, e.g., ether or acetate production.
• the physical characteristics and papermaking properties of this type of fiber make it appropriate for use in typical papermaking and absorbent product
• the second type of fiber is fiber that has been subjected to catalytic oxidation and then has been treated with an alkaline or caustic agent.
• the alkaline agent causes the fiber to break down at the sites of carbonyl functionality that were added through the oxidation process.
• This fiber has different physical and papermaking properties than the fiber only subjected to oxidation, but may exhibit the same or similar DP levels since the test used to measure viscosity and thereby DP subjects the fiber to a caustic agent, it would be evident to the skilled artisan that different alkaline agents and levels may provide different DP levels.
• the third type of fiber is fiber that has been subjected to catalytic oxidation and then been treated in an acid hydrolysis step.
• the acid hydrolysis results in a breakdown of the fiber, possibly to levels consistent with its ievel-off DP.
• Fiber produced as described can, in some embodiments, be treated with a surface active agent.
• the surface active agent for use in the present invention may be solid or iiquid.
• the surface active agent can be any surface active agent, including by not limited to softeners, debonders, and surfactants that is not substantive to the fiber, i.e., which does not interfere with its specific absorption rate.
• a surface active agent that is "not substantive" to the fiber exhibits an increase in specific absorption rate of 30% or less as measured using the pfi test as described herein.
• the specific absorption rate is increased by 25% or less, such as 20% or less, such as 15% or less, such as 10% or less.
• the addition of surfactant causes competition for the same sites on the cellulose as the test fluid. Thus, when a surfactant is too substantive, it reacts at too many sites reducing the absorption capability of the fiber.
• PFI is measured according to SCAN-C-33:80 Test Standard, Scandinavian Pulp, Paper and Board Testing Committee. The method is generally as follows. First, the sample is prepared using a PFS Pad Former. Turn on the vacuum and feed approximately 3.01 g fluff pulp into the pad former inlet. Turn off the vacuum, remove the test piece and place it on a balance to check the pad mass. Adjust the fluff mass to 3.00+ 0.01 g and record as assdry. Place the fluff into the test cylinder. Place the fluff containing cylinder in the shallow perforated dish of an Absorption Tester and turn the water valve on.
• the Tester will fun for 30 s before the display will read 00.00.
• the display reads 20 seconds, record the dry pad height to the nearest 0.5 mm (Heightdry).
• the start button press the start button again to prompt the tray to automatically raise the water and then record the time display (absorption time, T).
• the Tester wili continue to run for 30 seconds.
• the water tray will automatically lower and the time wili run for another 30S.
• the display reads 20 s, record the wet pad height to the nearest 0.5 mm
• Absorption Rate is T/ assdry. Specific Capacity (g/g) is (Masswet - SVankdry)/fv1assdry.
• Wet Bulk (cc/g) is [19.84 cm2 x Heightwet/3]/10.
• Dry Bulk is [19.64 cm2 x Heightdry/3]/10.
• the reference standard for comparison with the surfactant treated fiber is an identical fiber without the addition of surfactant.
• softeners and debonders are often available commercially only as complex mixtures rather than as single compounds. While the following discussion wili focus on the predominant species, it should be understood that commercially available mixtures would generally be used in practice. Suitable softener, debonder and surfactants will be readily apparent to the skilled artisan and are widely reported in the literature.
• Suitable surfactants include cationic surfactants, anionic, and nonionic surfactants that are not substantive to the fiber.
• the surfactant is a non-ionic surfactant.
• the surfactant is a cationic surfactant.
• the surfactant is a vegetable based surfactant, such as a vegetable based fatty acid, such as a vegetable based fatty acid quaternary ammonium salt Such compounds include DB999 and DB1009, both available from Cellulose Solutions.
• Other surfactants may be including, but not limited to Berol 388 an ethoxylated nonylphenol ether from Akzo Nobel, and TQ-2021 and TQ-2G28, both from Ashland, Inc.
• Biodegradable softeners can be utilized.
• Representative biodegradable cationic softeners/debonders are disclosed in U.S. Pat. Nos. 5,312,522; 5,415,737; 5,262,007; 5,264,082; and 5,223,096, ail of which are incorporated herein by reference in their entirety.
• the compounds are biodegradable diesters of quaternary ammonia compounds, quaternized amine-esters, and biodegradable vegetable oil based esters functional with quaternary ammonium chloride and diester dierucyldimethyi ammonium chloride and are representative biodegradable softeners.
• the surfactant is added in an amount of up to 8 lbs/ton, such as from 2 !bs/ton to 7 lbs/ton, such as from 4 lbs/ton to 7 lbs/ton such as from 6 lbs/ton to 7 lbs/ton.
• the surface active agent may be added at any point prior to forming rolls, bales, or sheets of pulp. According to one embodiment, the surface active agent is added just prior to the headbox of the pulp machine, specifically at the inlet of the primary cleaner feed pump.
• the fiber of the present invention has an improved filterability over the same fiber without the addition of surfactant when utilized in a viscose process.
• the filterability of a viscose solution comprising fiber of the invention has a filterability that is at least 10% lower than a viscose solution made in the same way with the identical fiber without surfactant, such as at least 15% lower, such as at least 30% lower, such as at least 40% lower, Filterability of the viscose solution is measured by the following method.
• a solution is placed in a nitrogen pressurized (27 psi) vessel with a 1 and 3/16ths inch filtered orifice on the bottom- the filter media is as follows from outside to inside the vessel: a perforated metal disk, a 20 mesh stainless steel screen, muslin cloth, a Whatman 54 filter paper and a 2 layer knap flannel with the fuzzy side up toward the contents of the vessel.
• the reference standard for comparison with the surfactant treated fiber is the identical fiber without the addition of surfactant.
• the surfactant treated fiber of the invention exhibits a limited increase in specific absorption rate, e.g., less than 30% with a concurrent decrease in filterability, e.g., at least 10%.
• the surfactant treated fiber has an increased specific absorption rate of less than 30% and a decreased filterability of at least 20%, such as at least 30%, such as at least
• the surfactant treated fiber has an increased specific absorption rate of less than 25% and a decreased filterability of at least 10%, such as at least about 20%, such as at least 30%, such as at least 40%.
• the surfactant treated fiber has an increased specific absorption rate of less than 20% and a decreased filterability of at least 0%, such as at !east about 20%, such as at least 30%, such as at feast 40%.
• the surfactant treated fiber has an increased specific absorption rate of less than 15% and a decreased filterability of at least 0%, such as at least about 20%, such as at least 30%, such as at least 40%.
• the surfactant treated fiber has an increased specific absorption rate of less than 10% and an decreased filterability of at least 10%, such as at least about 20%, such as at least 30%, such as at least 40%.
• modified kraft fiber of the present disclosure provides products made from the modified kraft fiber described herein, !n some embodiments, the products are those typically made from standard kraft fiber. In other embodiments, the products are those typically made from cotton linter or sulfite pulp. More specifically, modified fiber of the present invention can be used, without further modification, in the production of absorbent products and as a starting material in the preparation of chemical derivatives, such as ethers and esters. Heretofore, fiber has not been available which has been useful to replace both high alpha content cellulose, such as cotton and sulfite pulp, as well as traditional kraft fiber.
• phrases such as "which can be substituted for cotton linter (or sulfite pulp). . .” and “interchangeable with cotton linter (or sulfite pulp). . .” and “which can be used in place of cotton linter (or sulfite pulp). . .” and the like mean only that the fiber has properties suitable for use in the end application normally made using cotton linter (or sulfite pulp). The phrase is not intended to mean that the fiber necessarily has all the same characteristics as cotton linter (or sulfite pulp).
• the products are absorbent products, including, but not limited to, medical devices, including wound care (e.g., wound care).
• Absorbent products according to the present disclosure may be disposable.
• modified fiber according to the invention can be used as a whole or partial substitute for the bleached hardwood or softwood fiber that is typically used in the production of these products.
• modified cellulose fiber is in the form of fluff pulp and has one or more properties that make the modified cellulose fiber more effective than conventional fluff pulps in absorbent products. More specifically, modified fiber of the present invention may have improved compressibility and improved odor control, both of which make it desirable as a substitute for currently available fluff pulp fiber. Because of the improved compressibility of the fiber of the present disclosure, it is useful in
• the disclosure provides an ultrathin hygiene product comprising the modified kraft fibers of the disclosure.
• Ultra-thin fluff cores are typically used in, for example, feminine hygiene products or baby diapers.
• Other products which could be produced with the fiber of the present disclosure could be anything requiring an absorbent core or a compressed absorbent layer.
• fiber of the present invention exhibits no or no substantial loss of absorbency, but shows an improvement in flexibility.
• the absorbent product may be a product, such as a diaper or incontinence device that will absorb and hold urine.
• a product such as a diaper or incontinence device that will absorb and hold urine.
• Such devices generally contain an absorbent fluff core.
• the fibers of the present disclosure may be used to produce absorbent devices that can improve both urine wicking and retention thereby resulting in a more comfortable garment or device for the user.
• Fibers of the present disclosure can improve vertical wicking, horizontal wicking, and/or 45 degree wicking. According to one embodiment, absorbent products made with fibers of the present disclosure improve vertica! wicking over products made from fiber not subjected to an oxidation step by 10%. According to another embodiment, absorbent products made with fibers of the present disclosure improve vertica! wicking over products made from fiber not subjected to an oxidation step by 15%. According to yet another embodiment, absorbent products made with fibers of the present disclosure improve vertical wicking over products made from fiber not subjected to an oxidation step by at least 20%. Similar improvements can be seen in horizontai and 45 degree wicking.
• Fibers of the present disclosure can improve absorption rate and retention. According to one embodiment, absorbent products made with fibers of the present disclosure improve absorption rate over products made from fiber not subjected to an oxidation step by 10%. According to another embodiment, absorbent products made with fibers of the present disclosure improve absorption rate over products made from fiber not subjected to an oxidation step by 15%. According to yet another embodiment, absorbent products made with fibers of the present disclosure improve absorption rate over products made from fiber not subjected to an oxidation step by 20%. Similar improvements can be seen in horizontai and 45 degree wicking.
• absorbent products made with fibers of the present disclosure improve total absorption over products made from fiber not subjected to an oxidation step by 5%. According to another embodiment, absorbent products made with fibers of the present disclosure improve total absorption over products made from fiber not subjected to an oxidation step by 10%. According to yet another embodiment, absorbent products made with fibers of the present disclosure improve total absorption over products made from fiber not subjected to an oxidation step by 15%.
• the products as described when compared to products made with fibers not subjected to an oxidation step can exhibit improved flexibility (especially when used in the bending side of a multilayer core), improved dimensional stability after insult, and improved wet and dry strength
• the absorbent core for use in an absorbent device can include one or more layers of fiber that have been treated differently to improve the overall uptake and retention of the device.
• treated refers to any chemical or physical process that changes the absorbency, wicking or retention of the fiber.
• One common treatment is the addition of a surface active agent.
• the core can have a multitude of layers, for example, 2, 3 ,4 or 5.
• fibers of the present invention can be used in any layer of a multi-layer absorbent core and be treated or untreated.
• the fibers of the present invention are used in the top layer of the absorbent core.
• top refers to the place on the core that is first insulted with urine and closest to the skin.
• bottom refers to the layer farthest away from the user.
• Other layers may be referred to as “intermediate.”
• the fibers of the present disclosure may be used either "untreated,” which refers to fiber which has not been post-treated, for example, with a surfactant.
• the fibers may also be used in a "treated” state, which refers to fibers that have been modified by the inclusion of a surfactant. Treated or untreated fibers may be used in any layer and any combination.
• fibers of the present invention are used in the top layer of an absorbent core. According to another embodiment, the fibers of the present invention are used in the bottom layer of an absorbent core. According to yet another embodiment, the fibers of the invention are used in the intermediate layer of the absorbent core.
• fiber of the present disclosure is used in more than one layer of the absorbent core.
• the fiber of the present disclosure may be used in both the top and bottom layers of the absorbent core. Still further, the fiber of the present disclosure may be used in the top, bottom and intermediate layers of an absorbent core. According to one embodiment, the fibers in the top layer are treated fibers. According to another embodiment, the fibers in the bottom layer are treated fibers.
• the fibers in the intermediate layer are treated fibers.
• the treated and untreated fibers of the present disclosure may be combined in a single layer or may be used in separate layers of the absorbent core.
• the top layer of the absorbent core comprises fiber of the disclosure that has not been treated and the bottom layer of the absorbent core comprises fiber of the disclosure that has been treated.
• the absorbent core is made with treated fibers of the disclosure in the top layer, untreated fibers of the disclosure in one or more intermediate layers and treated fibers of the disclosure in the bottom layer.
• the density of the absorbent core may vary and will typically range from 0.10 g/cm 3 to 0.45 g/cm 3 . According to one embodiment, the absorbent core may have a density of about 0.15 g/cm 3 . According to another embodiment, the absorbent core may have a density of about 0.20 g/cm 3 . According to yet another embodiment, the absorbent core may have a density of about 0.25 g/cm 3 .
• Modified fiber of the present invention may, without further modification, also be used in the production of absorbent products including, but not limited to, tissue, towel, napkin and other paper products which are formed on a traditional papermaking machine.
• Traditional papermaking processes involve the preparation of an aqueous fiber slurry which is typically deposited on a forming wire where the water is thereafter removed.
• the increased functionality of the modified cellulose fibers of the present disclosure may provide improved product characteristics in products including these modified fibers.
• the modified fiber of the present invention may cause the products made therewith to exhibit improvements in strength, likely associated with the increased functionality of the fibers.
• the modified fiber of the invention may also result in products having improved softness.
• the modified fiber of the present disclosure can be used in the manufacture of cellulose ethers (for example carboxymethylcellulose) and esters as a substitute for fiber with very high DP from about 2950 to about 3980 (i.e., fiber having a viscosity, as measured by 0.5% Capillary CED, ranging from about 30 mPa-s to about 60 mPa ⁇ s) and a very high percentage of cellulose (for example 95% or greater) such as those derived from cotton Sinters and from bleached softwood fibers produced by the acid sulfite pulping process.
• the modified fiber of the present invention which has not been subjected to acid hydrolysis will generally receive such an acid hydrolysis treatment in the production process for creating cellulose ethers or esters.
• the second and third types of fiber are produced through processes that derivatize or hydrolyze the fiber. These fibers can also be useful in the production of absorbent articles, absorbent paper products and cellulose derivatives including ethers and esters.
• this disclosure provides a modified kraft fiber that can be used as a substitute for cotton iinter or sulfite pulp. In some embodiments, this disclosure provides a modified kraft fiber that can be used as a substitute for cotton Iinter or sulfite pulp, for example in the manufacture of cellulose ethers, cellulose acetates and microcrystalline cellulose.
• aldehyde content relative to conventional kraft pulp provides additional active sites for etherification to end-products such as carboxymethyice!lu!ose, methylcellulose, hydroxypropylceiiuiose, and the like, enabling production of a fiber that can be used for both papermaking and cellulose derivatives.
• the modified kraft fiber has chemical properties that make it suitable for the manufacture of cellulose ethers.
• the disclosure provides a cellulose ether derived from a modified kraft fiber as described.
• the cellulose ether is chosen from ethylcellulose, methylcellulose, hydroxypropyi cellulose, carboxymethyi cellulose, hydroxypropyi methylcellulose, and hydroxyethyl methyl cellulose, it is believed that the cellulose ethers of the disclosure may be used in any application where cellulose ethers are traditionally used.
• the cellulose ethers of the disclosure may be used in coatings, inks, binders, controlled release drug tablets, and films.
• the modified kraft fiber has chemical properties that make it suitable for the manufacture of cellulose esters.
• the disclosure provides a cellulose ester, such as a cellulose acetate, derived from modified kraft fibers of the disclosure.
• the disclosure provides a product comprising a cellulose acetate derived from the modified kraft fiber of the disclosure.
• the cellulose esters of the disclosure may be used in, home furnishings, cigarettes, inks, absorbent products, medical devices, and plastics including, for example, LCD and plasma screens and windshields.
• the modified kraft fiber has chemical properties that make it suitable for the manufacture of microcrystalline cellulose.
• Microcrystalline cellulose production requires relatively clean, highly purified starting DC!u!osic material. As such, traditionally, expensive sulfite pulps have been predominantly used for its production.
• the present disclosure provides microcrystalline cellulose derived from modified kraft fiber of the disclosure.
• the disclosure provides a cost-effective cellulose source for microcrystalline cellulose production.
• the microcrystai!ine cellulose is derived from modified kraft fiber having a DP which is less than about 100, for example, less than about 75 or less than about 50.
• the microcrystalline cellulose is derived from modified kraft fiber having an R10 value ranging from about 65% to about 85%, for instance from about 70% to about 85%, or from about 75% to about 85% and an R18 value ranging from about 75% to about 90%, for instance from about 80% to about 90%, for example from about 80% to about 87%.
• the modified cellulose of the disclosure may be used in any application that microcrystaliine cellulose has traditionally been used.
• the modified cellulose of the disclosure may be used in pharmaceutical or nutraceutical applications, food
• the modified ce!Sulose of the disclosure may be a binder, diluent, disintegrant, lubricant, tabietting aid, stabilizer, texturizing agent, fat rep!acer, bulking agent, anticaking agent, foaming agent, emulsifier, thickener, separating agent, gelling agent, carrier material, opacifier, or viscosity modifier.
• the microcrystalline cellulose is a colloid
• the disclosure provides a pharmaceutical product comprising a microcrystalline cellulose that has been produced from a modified kraft fiber of the disclosure that has been hydrolyzed.
• the pharmaceutical product may be any pharmaceutical product in which microcrystalline DCluiose has traditionally been used.
• the pharmaceutical product may be chosen from tablets and capsules.
• the microcrystalline cellulose of the present disclosure may be a diluent, a disintegrant, a binder, a compression aid, coating and/or a lubricant, !n other embodiments, the disclosure provides a pharmaceutical product comprising at least one modified derivatized kraft fiber of the disclosure, such as a hydrolyzed modified kraft fiber.
• the disclosure provides a food product comprising a bleached kraft fiber of the disclosure that has been hydrolyzed. In some embodiments, the disclosure provides a food product comprising at least one product derived from bleached kraft fiber of the disclosure. In further embodiments, the disclosure provides a food product comprising microcrystaliine cellulose derived from kraft fibers of the disclosure, !n some embodiments, the food product comprises colloidal microcrystal!ine cellulose derived from kraft fibers of the disclosure.
• the food product may be any food product in which microcrystaliine cellulose has traditionally been used.
• microcrystaliine cellulose may be used as a food category in which microcrystaliine cellulose may be used as well known to those of ordinary skill in the art, and can be found, for example, in the Codex Alimentarius, for instance at Table 3.
• microcrystaliine cellulose derived from chemically modified kraft fibers of the disclosure may be an anticaking agent, bulking agent, emulsifier, foaming agent, stabilizer, thickener, gelling agent, and/or suspension agent.
• microcrystaliine cellulose derived from chemically modified kraft fibers according to the disclosure may also be envisaged by persons of ordinary skill in the art. Such products may be found, for example, in cosmetic and industrial applications.
• carbonyl (Cu, No, - 0.07)/0.6, from Biomacromolecules 2002, 3, 969-975.
• Cellulose content is calculated from carbohydrate composition according to the formula: Ceilulose TM Glucan ⁇ ( annan/3), from TAPPI
• Hemiceilulose content is calculated from the sum of sugars minus the cellulose content.
• Fiber length and coarseness is determined on a
• Water Retention Value is determined according to TAPPI UM 258,
• iron content is determined by acid digestion and analysis by ICP.
• Ash content is determined according to TAPPI T21 1 -omQ2.
• Peroxide residual is determined according to Interox procedure.
• Brightness is determined according to TAPPi T525-ornG2.
• Porosity is determined according to TAPPI 460- om02.
• Burst factor is determined according to TAPPI T403-om02,
• Tear factor is determined according to TAPPi T414-om98.
• Breaking length and stretch are determined according to TAPPI T494-om01. 21 ; 5. Opacity is determined according to TAPPi ⁇ 425- omOl
• Frazier porosity is determined on a Frazier Low Air Permeability Instrument from Frazier
• Fiber Length and shape factor are determined on an L&W Fiber Tester from Lorentzen & Wettre, Kista, Sweden, according to the manufacturer's standard procedures.
• a semi-bleached or mostly bleached kraft pulp may be treated with an acid, iron and hydrogen peroxide for the purposes of reducing the fiber's viscosity or DP.
• the fiber may be adjusted to a pH of from about 2 to about 5 (if not already in this range) with sulfuric, hydrochloric, acetic acid, or filtrate from the washer of an acidic bleach stage, such as a chlorine dioxide stage.
• Iron may be added in the form of Fe +2 » for example iron may be added as ferrous sulfate heptahydrate ⁇ FeS0 4 7H 2 0).
• the ferrous sulfate may be dissolved in water at a concentration ranging from about 0.1 to about 48.5 g/L.
• the ferrous sulfate solution may be added at an application rate ranging from about 25 to about 200 ppm as Fe +2 based on the dry weight of pulp.
• the ferrous sulfate solution may then be mixed thoroughly with the pH-adjusted pulp at a consistency of from about 1 % to about 15% measured as dry pulp content of the total wet530p mass.
• Hydrogen peroxide (H2O2) may then be added as a solution with a concentration of from about 1% to about 50% by weight of H 2 0 2 in water, at an amount of from about 0,1 % to about 3% based on the dry weight of the memep.
• the pulp at a pH of from about 2 to about 5 mixed with the ferrous sulfate and peroxide may be allowed to react for a time ranging from about 40 to about 80 minutes at a temperature of from about 60 to about 80 degrees C.
• the degree of viscosity (or DP) reduction is dependent on the amount of peroxide consumed in the reaction, which is a function of the concentration and amount of peroxide and iron applied and the retention time and temperature.
• the treatment may be accomplished in a typical five-stage bleach plant with the standard sequence of D 0 E1 D1 E2 D2. With that scheme, no additional tanks, pumps, mixers, towers, or washers are required.
• the fourth or E2 stage may be preferably used for the treatment
• the fiber on the D1 stage washer may be adjusted to a pH of from about 2 to about 5, as needed by addition of acid or of filtrate from the D2 stage.
• a ferrous sulfate solution may be added to the pulp either (1) by spraying it on the D1 stage washer mat through the existing shower headers or a new header, (2) added through a spray mechanism at the repulper, or (3) added through an addition point before a mixer or pump for the fourth stage.
• the peroxide as a solution may be added following the ferrous sulfate at an addition point in a mixer or pump before the fourth stage tower. Steam may also be added as needed before the tower in a steam mixer. The pulp may then be reacted in the tower for an appropriate retention time. The chemically modified pulp may then be washed on the fourth stage washer in a normal fashion. Additional bleaching may be optionally accomplished following the treatment by the fifth or D2 stage operated in a normal fashion.
• Southern pine cellulose was digested and oxygen delignified in a conventional two-stage oxygen delignification step to a kappa number of from about 9 to about 10.
• the delignified pulp was bleached in a five-stage bleach plant, with a sequence of D 0 ⁇ EO)D1 E2D2, Before the fourth or E2 stage, the pH of the pulp was adjusted to a range of from about 2 to about 5 with filtrate from a D stage of the sequence.
• Fibers were prepared as described in Mill Method A, except that the pot was treated with 0.6% peroxide and 75 ppm Fe +2 .
• Fibers were prepared as described in Mill Method A, except that the perpetratp was treated with 1.4% peroxide and 100 ppm Fe +2 ,
• Samples of fibers prepared according to Mill Methods A were collected following the five-stage bleaching sequence described above.
• Several properties of these samples along with a standard fluff grade fiber GP Leaf River Cellulose, New Augusta, MS; Sample 1
• a commercially available sample PEACHTM, sold by Weyerhaeuser Co.; Sample 5
• modified fiber according to the present invention is unexpectedly different from both the control fiber, Sample 1 , and an alternative commercially available oxidized fiber, Sample 5, in the total carbonyl content as well as the carboxyl content and aldehyde content.
• additional carbonyl functionality may be in the form of other ketones.
• the data shows that we achieve relatively high levels of aldehydes while retaining carboxylic acid groups and while retaining a near unify ratio of aldehydes to total carbonyl groups (as seen in Table 1 , about 1.0 (0.95) to 1.6). This is more surprising in a fiber that exhibits high brightness and that is also relatively strong and absorbent.
• the standard fluff grade fiber ⁇ Sample 1) had a carboxyl content of 3.13 meq/100 g, and an aldehyde content of 0.97 meq/100 g. After a low-dose treatment with 0.2% H2O2 and 25 ppm Fe ⁇ 2
• Example 2 or a higher-dose treatment with 0.6% H2O2 and 75 ppm Fe +2 (Sample 3), or a higher-dose treatment with 1.4% H 2 0 2 and 100 ppm Fe +2 (Sample 4), the fiber length and calculated cellulose content were relatively unchanged, and fiber strength as measured by the wet zero span method was diminished somewhat, yet the carboxyl, carbonyl, and aldehyde contents were all elevated, indicating extensive oxidation of the cellulose.
• sample 5 a commercially available sample of oxidized kraft softwood southern pine fiber manufactured by an alternative method (Sample 5), shows significant reduction in fiber length and about a 70 percent loss in fiber strength as measured by the wet zero span method as compared to the fluff grade fiber reported as Sample 1.
• the aldehyde content of Sample 5 was virtually unchanged compared to the standard fluff grade fibers, while the inventive fibers prepared by mill methods A-C (Samples 2-4) had highly elevated aldehyde levels representing from about 70 to about 100 percent of the total calculated carbonyl content of the cellulose.
• the PEACH® aldehyde level was less than 30 percent of the total calculated carbonyl content of the cellulose.
• the ratio of total carbonyl to aldehyde would appear to be a good indicator of a fiber that has the broad applicability of the modified fibers within the scope of this disclosure, particularly if the ratio is in the range of about 1 to about 2, as are Samples 2-4.
• the modified cellulose fibers according to this disclosure may have a freeness comparable to standard fluff fibers that have not undergone an oxidation treatment in the bleaching sequence.
• OD(EOP)D(EP)D bleach plant with a 0.5% Capillary CED viscosity of about 14,6 mPa*s was treated at about 10% consistency with hydrogen peroxide
• a Southern pine pulp from the D1 stage of a OD 0 (EO)D1 (EP)D2 sequence with a 0,5% Capillary CED viscosity of 15.8 mPa*s (DPw 2085) was treated at 10% consistency with hydrogen peroxide applications of either 0.25% or 0.5% by weight on pulp and 25, 50, or 100 ppm of Fe ⁇ 2 added as
• the Fe +2 was added as a solution in water and mixed thoroughly with the pulp.
• the hydrogen peroxide was a 3% solution in water that was then mixed with the pulp, and the mixed pulp was held in a water bath for 1 hour at 78°C. After the reaction time, the pulp was filtered and the filtrate measured for pH and residual peroxide. The pulp was washed and the 0.5% Capillary CED viscosity determined according to TAPPI T230. The results are shown in Table 6.
• OD(EO)D(EP)D bleaching sequence after the extent of delignification in the kraft and oxygen stages was increased to produce a pulp with a lower DPw or 0.5% Capillary CED viscosity.
• the starting 0.5% Capillary CED viscosity was 12.7 mPa*s (DPw 1834).
• Either 0.50 or 1.0% hydrogen peroxide was added with 100 ppm of Fe +2 .
• Other treatment conditions were 10% consistency, 78° C, and 1 hour treatment time. The results are shown in Table 8.
• OD(EO)D(EP)D sequence The starting 0.5% Capillary CED viscosity was 1 1.8 mPa » s (DPw 1726). Either 1.0%, 1.5%, or 2% hydrogen peroxide was added with 75, 150, or 200 pprn of Fe +2 . Other treatment conditions were 10% 81 consistency, 78° C, and 1.5 hour treatment time. The results are shown in Table 10.
• a Southern pine pulp was collected from the D1 stage of a OD(EO)D(EP)D sequence.
• the starting 0.5% Capillary CED viscosity was 14.4 mPa « s (DPw 1986).
• Either 1.0%, 1.5%, or 2% hydrogen peroxide was added with 75, 50, or 200 ppm of Fe ⁇ 2 .
• Other treatment conditions were 10% consistency, 78°C, and 1.5 hour reaction time. The results are shown in Table 11.
• a Southern pine pulp was collected from the D1 stage of a OD(EO)D(EP)D sequence.
• the starting 0.5% Capillary CED viscosity was 15.3 82 mPa-s (DPw 2061).
• Hydrogen peroxide was added at 3% on pulp with 200 ppm of Fe +2 .
• Other treatment conditions were 10% consistency, 80° C, and 1 .5 hour reaction time. The results are shown in Table 12.
• a Southern pine pulp was collected from the D1 stage of a
• FeS0 4 -7H 2 0 was sprayed on the pulp at the washer repulper of the D1 stage at an application rate of 150 ppm as Fe +2 , No caustic (NaOH) was added to the E2 stage and the peroxide application was increased to 0.75%.
• the retention time was approximately 1 hour and the temperature was 79° C.
• the pH was 2.9.
• the treated pulp was washed on a vacuum drum washer and subsequently treated in the final D2 stage with 0.7% CI0 2 for approximately 2 hours at 91° C.
• the 0.5% Capillary CED viscosity of the final bleached pulp was 6.5 mPa-s (DPw 1084) and the ISO brightness was 87.
• Example 13 The pulp produced in Example 13 was made into a pulp board on a Fourdrinier type pulp dryer with standard dryer cans. Samples of a control pulp and the pulp of the present invention (ULDP) were collected and analyzed for chemical composition and fiber properties. The results are shown in Table 14.
• the treated pulp had a higher alkali solubility in 10% and 18% NaOH and a higher aldehyde and total carbonyl content.
• the ULDP was significantly lower in DP as measured by 0.5% Capillary CED viscosity,
• the decrease in fiber integrity was also determined by a reduction in wet zero span tensile strength. Despite the significant reduction in DPw, the fiber length and freeness were essentially unchanged. There were no deleterious effects on drainage or board making on the machine.
• the E2 (EP) stage of a OD(EO)D(EP)D sequence was altered to produce the ultra low degree of polymerization pulp in a similar manner as Example 13.
• the FeS0 4 '7H 2 G was added at 75 ppm as Fe ⁇ 2 and the hydrogen peroxide applied in the E2 stage was 0.8%.
• the pH of the treatment stage was 3.0, the temperature was 82° C, and the retention time was approximately 80 minutes.
• the pulp was washed and then treated in a D2 stage with 0.2% CI0 2 at 92° C for approximately 150 minutes.
• the 0.5% Capillary CED viscosity of the fully bleached pulp was 5.5 mPa e s (DPw 914) and the ISO brightness was 88.2,
• Example 15 The pulp produced in Example 15 was made into a pulp board on a Fourd nier type pulp dryer with an airborne FlaktTM dryer section. Samples of a standard pulp and the pulp of the present invention (ULDP) were collected and analyzed for chemical composition and fiber properties. The results are shown in Table 15.
• ULDP standard pulp and the pulp of the present invention
• the treated pulp had a higher alkali solubility in 10% and 18% NaOH and a higher aldehyde and total carbonyl content.
• the ULDP was significantly lower in DP as measured by 0.5% Capillary CED viscosity and lower wet zero span breaking length.
• the brightness was still an acceptable value of 88.2.
• the treatment preserved the fiber length and freeness and there were no operational issues forming and drying the board.
• the E2 (EP) stage of a OD(EO)D(EP)D sequence was altered to produce a low degree of polymerization pulp in a similar manner as Example 13, In this case the FeS0 4 -7H 2 0 was added at 25 ppm as Fe +2 and the hydrogen peroxide applied in the E2 stage was 0.2%.
• the pH of the treatment stage was 3.0, the temperature was 82° C and the retention time was approximately 80 minutes.
• the pulp was washed then treated in a D2 stage with 0.2% CI0 2 at 92° C for approximately 150 minutes.
• the 0.5% Capillary CED viscosity of the fully bleached pulp was 8.9 mPa*s (DPw 1423) and the ISO brightness was 89.
• Example 15 The pulp produced in Example 15 was made into a pulp board on a Fourdrinier type pulp dryer with an airborne FlaktTM dryer section. Samples of a standard pulp and the low degree of polymerization pulp of the present invention (LDP) were collected and analyzed for chemical composition and fiber properties. The results are shown in Table 16.
• LDP low degree of polymerization pulp of the present invention
• the treated pulp had a higher alkali solubility in 10% and 18% NaOH and a higher aldehyde and total carbonyi content.
• the LDP was lower in DP as measured by 0.5% Capillary CED viscosity. There was a minimal loss in brightness.
• the treatment preserved the fiber length and there were no operational issues forming and drying the board.
• a Southern pine pulp was collected from the D1 stage of a
• OD(EO)D(EP)D sequence The starting 0.5% Capillary CED viscosity was 14.9 mPa*s (DPw 2028). Either 1.0% or 2% hydrogen peroxide was added with 100 or 200 ppm of Fe +2 respectively. Other treatment conditions were 10% consistency, 80° C, and 1 hour retention time. These fluff pulps were then slurried with deionized water, wet!aid on a screen to form a fiber mat, dewatered via roller press, and dried at 250° F. The dry sheets were defibrated and airformed into 4" x 7" airlaid pads weighing 8.5 grams (air dried) using a Kamas Laboratory Hammermill (Kamas Industries, Sweden). A single, complete coverage sheet of nonwoven coverstock was applied to one face of each pad and the samples were densified using a Carver hydraulic platen press applying a load of 145 psig.
• containers having a removable lid fitted with a check valve and sampling port of 1 ⁇ 4" ID Tygon® tubing.
• a delivery device capable of applying a 0.1 psi load across the entirety of the sample.
• the delivery device was removed from the sample, the lid, with sealed sampling port, was fitted to the container, and a countdown timer started.
• the modified chemical cellulose produced was made into a pulp board on a Fourdrinier type pulp dryer with an airborne FlaktTM dryer section. Samples of this product and control kraft pulp board v3 ⁇ 4rerere defibrated using the Kamas laboratory hammermill. Optical analysis of fiber properties were performed on both pre and post Kamas mill samples via HiRes Fiber Quality Analyzer available from Optest Equipment, Inc., Hawkesbury, ON, Canada, according to the manufacturer's protocols. The results are depicted in the tabk
• the ULDP fibers prepared in accordance with the disclosure have higher kink and curl than control fibers not treated with iron and peroxide.
• Synthetic urine was prepared by dissolving 2% Urea, 0.9% Sodium Chloride, and 0.24% nutrient broth (CriterionTM brand available through Hardy Diagnostics, Santa Maria, CA) in deionized water, and adding an aliquot of Proteus Vulgaris resulting in a starting bacterial concentration of 1.4 x 10 7 CFU/m!.
• the pad described above was then placed in a headspace chamber as described in Example 20 and insulted with 80 ml of the synthetic urine solution. Immediately after insult, the chamber was sealed and placed in an environment with a temperature of 30° C. Drager sampling was performed in series at time intervals of four hours and seven hours. The experiment was repeated three times, and the average results are reported in Table 21.
• Table 21
• modified cellulose fibers produced within the scope of this disclosure versus composite structures produced with standard kraft southern pine fibers.
• OD(EO)D1 (EP)D2 sequence The starting 0.5% Capillary CED viscosity was 14.1 mPa « s. Hydrogen peroxide was added as 1.5% based on the dry weight of the pulp with 150 ppm of Fe +2 . As used herein, "P*" is used to indicate an iron and hydrogen peroxide treatment stage The treatment was conducted at 10% consistency at a temperature of 78° C for 1 hour in the fourth stage of the sequence. This treated pulp was then washed and bleached in D2 stage with 0,25% C!Oa for 2 hours at 78° C. The results are shown in Table 22.
• a Southern pine pulp was collected from the D2 stage of the same bleach plant as above with the same starting Capillary CED viscosity and was treated with hydrogen peroxide and Fe ⁇ as described above. Hydrogen peroxide was added as 1.5% based on the dry weight of the pulp with 150 ppm of Fe* 2 , he properties of this treated pulp are depicted in Table 24.
• a sample of ULDP from Example 21 was acid hydrolyzed with M HCI at 5% consistency for 3 hours at 122° C.
• the initial pulp from the D1 stage, the ULDP, and the acid hydrolyzed ULDP were tested for average molecular weight or degree of polymerization by the method below.
• Three pulp samples were grounded to pass a 20 mesh screen. Cellulose samples (15 mg) were placed in separate test tubes equipped with micro stir bars and dried overnight under vacuum at 40 °C. The test tubes were then capped with rubber septa. Anhydrous pyridine (4.00 mL) and phenyl isocyanate (0.50 mL) were added sequentially via syringe.
• test tubes were placed in an oil bath at 70 °C and allowed to stir for 48 h. Methanol (1.00 mL) was added to quench any remaining phenyl isocyanate. The contents of each test tube were then added dropwise to a 7:3 methanol/water mixture (100 mL) to promote precipitation of the derivatized cellulose. The solids were collected by filtration and then washed with methanol/water (1 x 50 mL) followed by water (2 x 50 mL). The derivatized cellulose was then dried overnight under vacuum at 40 °C.
• modified cellulose after acid hydrolysis according to the disclosure can have a DPn of 48.
• Leaf River ULDP fibers and standard softwood fibers were made into handsheets by slurrying the fiber, adjusting the pH to about 5.5, and then adding, as a temporary wet strength agent, a glyoxyiated poiyacrylamide from Kemira Chemicals. The fibers were then formed, pressed into sheets and dried. The characteristics of the sheets were measured by known methods. The results ⁇ ported in Table 28 below.
• I JLDP according 1 to the disclosure may be us ed in pr( )duction of wet pressed Daper, As is shown in
• the products were tested for fluid acquisition, profile, and capacity.
• the fluid acquisition was done by applying 5 ml of 0,9% saline solution to the sample then letting the fluid wick for 5 minutes. After 5 minutes, the rewet was taken for 2 minutes using standard laboratory filter paper.
• the products had the characteristics shown in Tables 41 and 42.
• Materi als Testing Ser vice ti 3sted the wet tensile strenc 3th for each product in the mach ine direction using ten samples, a gauge I ength of 5.00 cms, a sample width of 1 3 cms., a cross »head speed of 2.5 cm/min and g i load ceil of
• Materi als Testing Service tested the dry tensile i streng th and percent elongation f or each produc t in th 3 machine direction ⁇ sing ten samples, a gauge length of 5. 00 cms. a sample wi dth of 1 .3 cms., a cro sshec id speed of
• a fiber derived from a bleached softwood kraft pulp in which the fiber has an average fiber length of at least about 2 mm, preferably at least about 2.2 mm, for instance at least about 2.3 mm, or for example at least about 2.4 mm, or for example about 2.5 mm, more preferably from about 2 mm to about 3.7 mm, still more preferably from about 2.2 mm to about 3.7 mm.
• a fiber derived from a bleached hardwood kraft pulp in which the fiber has an average fiber length of at least about 0.75 mm, preferably at least about 0.85 mm, or at least about 0.95 mm, or more preferably at least about 1.15, or ranging from about 0.75 mm to about 1.25 mm.
• D. A fiber derived from a bleached softwood kraft pulp, in which the fiber has a 0,5% capillary CED viscosity of about 13 mPa « s or less, an average fiber length of at least about 2 mm, and an ISO brightness ranging from about 85 to about 95.
• a fiber according to one of embodiments A- in which the fiber has an S10 caustic solubility ranging from about 16% to about
• a fiber according to one of embodiments A ⁇ Q in which the fiber has a AR or about 3.0 or greater, preferably about 6.0 or greater.
• freeness Canadian Standard Freeness
• AAA A fiber according to one of embodiments A-WW, in which the fiber has a fiber strength, measured by wet zero span breaking length, of at least about 6 km,
• ISO brightness ranges from about 85 to about 92, preferably from about 86 to about 90, more preferably from about 87 to about 90 or from about 88 to about 90 ISO.
• ISO brightness is at least about 85, preferably at least about 88, more preferably at least about 87, particularly at least about 88, more particularly at least about 89 or about 90 ISO,
• HHH A fiber according to one of embodiments A-FFF, in which the
• ISO brightness is at least about 87.
• ISO brightness is at least about 89.
• ISO brightness is at least about 90
• LLL A fiber according to any of the embodiments above, wherein the fiber has about the same length as standard kraft fiber, M M, A fiber according to one of embodiments A-S and SS-MM , having higher carboxyl content than standard kraft fiber. HHH, A fiber according to one of embodiments A-S and SS-NNN, having higher aldehyde content than standard kraft fiber.
• a fiber according to embodiments A-S and SS-MMM having a ratio of total aldehyde to carboxyl content of greater than about 0,3, preferably greater than about 0.5, more preferably greater than about 1.4, or for example ranging from about 0,3 to about 0.5. or ranging from about 0.5 to about 1 , or ranging from about 1 to about 1.5.
• R10 value ranges from about 85% to about 85%, preferably from about 70% to about 85%, more preferably from about 75% to about 85%.
• R18 value ranges from about 75% to about 90%, preferably from about 80% to about 90%, more preferably from about 80% to about 87%.
• UUU A fiber according to any of the embodiments above, in which the fiber has odor control properties.
• YYY A fiber according to any of the embodiments above, in which the copper number is less than 2, preferably less than 1.9, more preferably less than 1.8, still more preferably less than 1.7. ZZZ.
• AAAA A fiber according to any of the embodiments above, having a hemicelluiose content substantially the same as standard kraft fiber, for instance, ranging from about 16% to about 18% when the fiber is a softwood fiber or ranging from about 18% to about 25% when the fiber is a hardwood fiber.
• BBBB A fiber according to any of the embodiments above, in which the fiber exhibits antimicrobial and/or antiviral activity.
• CCCC A fiber according to any of embodiments B-C or L-CCCC, in which the DP ranges from about 350 to about 1880, for example from about 710 to about 1880, preferably from about 350 to about 910, or for example from about 1180 to about 1860.
• a fiber according to embodiments A-OOO in which the fiber may be compressed to a density of at least about 0.210 g/cc, preferably at least about 0.220 g/cc, more preferably at least about 0.230 g/cc, particularly at least about 0.240 g/cc.
• a fiber according to embodiments A-OOO in which the fiber can be compressed to a density of at least about 8% higher than the density of standard kraft fiber, particularly ranging from about 8% to about 18% higher than the density of standard kraft fiber, preferably from about 8% to about 10%, or from about 12% to about 16% higher, more preferably from about 13% to about 16% higher, more preferably from about 14% to about 18% higher, in particular from about 15% to about 16% higher.

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