# US 11,111,628 B2 · Modified cellulose from chemical kraft fiber and methods of making and using the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,111,628 B2 - Document ID: US11111628B2 - Status: Granted - Kind: B2 - Application number: 16/933,167 - Filed: 2020-07-20 - Published: 2020-11-05 - Granted: 2021-09-07 - Earliest claimed: 2009-05-28 - Assignees: GP Cellulose GmbH - Applicants: GP Cellulose GmbH - Inventors: Arthur J. Nonni; Charles E. Courchene; Christopher Michael Slone; Peter R. Abitz - Web page: https://patentgrep.com/patent/US11111628B2 ## CPC - D21C 9/163: {with peroxides} - A61F 13/53: characterised by the absorbing medium (A61F13/20 takes precedence) - D21C 9/002: {by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives} - D21C 9/1036: {Use of compounds accelerating or improving the efficiency of the processes} - D21C 9/144: {with ClO2/Cl2 and other bleaching agents in a multistage process} - D21H 11/04: Kraft or sulfate pulp - D21H 11/16: modified by a particular after-treatment - D21H 11/20: Chemically or biochemically modified fibres - Y10T 428/298: Physical dimension - D21C: PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR - A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C) - D21H: PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A modified kraft pulp fiber with unique properties is provided. The modified fiber can be a modified bleached kraft fiber that is almost indistinguishable from its conventional counterpart, except that it has a low degree of polymerization (DP). Methods for making the modified fiber and products made from it are also provided. The method can be a one step acidic, iron catalyzed peroxide treatment process that can be incorporated into a single stage of a multi-stage bleaching process. The products can be chemical cellulose feedstocks, microcrystalline cellulose feedstocks, fluff pulps and products made from them. ## Claims ### Claim 1 A fluff pulp comprising a kraft fiber bleached according to a multi-stage bleaching process, wherein at least one stage of the bleaching process comprises oxidizing the kraft fiber with at least one peroxide and at least one catalyst under acidic conditions, wherein the at least one catalyst comprises copper or a combination of copper and iron, and wherein the kraft fiber has an aldehyde content ranging from about 1 meq/100 g to about 9 meq/100 g, a carboxyl content of at least about 3 meq/100 g, a 0.5% capillary CED viscosity of less than about 10 mPa·s, an ISO brightness of at least about 88, a length-weighted average fiber length of at least about 2 mm, and wherein the fluff pulp fiber does not comprise an optical brightening agent. ### Claim 2 (depends on 1) The fluff pulp of claim 1, wherein the at least one catalyst comprises copper sulfate. ### Claim 3 (depends on 1) The fluff pulp of claim 1, wherein the at least one catalyst comprises a combination of a copper catalyst and an iron catalyst and the iron catalyst comprises at least one of ferrous sulfate, ferrous chloride, ferrous ammonium sulfate, ferric chloride, ferric ammonium sulfate, and ferric ammonium citrate. ### Claim 4 (depends on 2) The fluff pulp of claim 2, wherein the copper sulfate is added in an amount ranging from about 100 to about 200 ppm copper based on the dry weight of the kraft fiber. ### Claim 5 (depends on 3) The fluff pulp of claim 3, wherein the iron catalyst is added in an amount ranging from about 25 to about 200 ppm iron based on the dry weight of the kraft fiber. ### Claim 6 (depends on 1) The fluff pulp of claim 1, wherein the peroxide is hydrogen peroxide. ### Claim 7 (depends on 6) The fluff pulp of claim 6, wherein the hydrogen peroxide is added in an amount of from about 0.1% to about 1.5%, based on the dry weight of the kraft fiber. ### Claim 8 (depends on 1) The fluff pulp of claim 1, wherein the pH of the oxidation bleaching stage ranges from about 2 to about 6. ### Claim 9 (depends on 1) The fluff pulp of claim 1, wherein the multi-stage bleaching process has no alkaline bleaching stage following the oxidation bleaching stage. ### Claim 10 (depends on 1) The fluff pulp of claim 1, wherein the multi-stage bleaching process has three successive acidic bleaching stages that each comprise a reactor operating under acidic conditions. ### Claim 11 (depends on 1) The fluff pulp of claim 1, wherein at least two stages of the bleaching process comprises oxidizing the kraft fiber with at least one peroxide and at least one catalyst under acidic conditions, and wherein the at least one catalyst comprises copper or a combination of copper and iron. ### Claim 12 (depends on 1) The fluff pulp of claim 1, wherein the kraft fiber is digested and oxygen delignified to a kappa number from about 6 to about 14 prior to the multi-stage bleaching process. ### Claim 13 (depends on 1) The fluff pulp of claim 1, wherein the carboxyl content is from about 3 to about 6 meq/100 g. ### Claim 14 (depends on 1) The fluff pulp of claim 1, wherein the aldehyde content is from about 4 meq/100 g to about 9 meq/100 g. ### Claim 15 (depends on 1) The fluff pulp of claim 1, wherein the 0.5% capillary CED viscosity is less than about 7 mPa·s. ### Claim 16 (depends on 1) The fluff pulp of claim 1, wherein the kraft fiber further has a kappa number less than about 1.9. ### Claim 17 (depends on 1) The fluff pulp of claim 1, wherein the kraft fiber further has a hemicellulose content from about 16% to about 25%. ### Claim 18 (depends on 1) The fluff pulp of claim 1, wherein the kraft fiber further has copper number greater than about 2.5.