EP1866477B1 - Improved composition and processes for paper production - Google Patents
Improved composition and processes for paper production Download PDFInfo
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- EP1866477B1 EP1866477B1 EP06740857.5A EP06740857A EP1866477B1 EP 1866477 B1 EP1866477 B1 EP 1866477B1 EP 06740857 A EP06740857 A EP 06740857A EP 1866477 B1 EP1866477 B1 EP 1866477B1
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- pulp
- salts
- paper
- acid
- composition
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Classifications
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1026—Other features in bleaching processes
- D21C9/1042—Use of chelating agents
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1084—Bleaching ; Apparatus therefor with reducing compounds
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/03—Non-macromolecular organic compounds
- D21H17/05—Non-macromolecular organic compounds containing elements other than carbon and hydrogen only
- D21H17/09—Sulfur-containing compounds
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/03—Non-macromolecular organic compounds
- D21H17/05—Non-macromolecular organic compounds containing elements other than carbon and hydrogen only
- D21H17/14—Carboxylic acids; Derivatives thereof
- D21H17/15—Polycarboxylic acids, e.g. maleic acid
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
- D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
- D21H21/30—Luminescent or fluorescent substances, e.g. for optical bleaching
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
- D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
- D21H21/32—Bleaching agents
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
- D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
- D21H23/22—Addition to the formed paper
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H5/00—Special paper or cardboard not otherwise provided for
- D21H5/0005—Processes or apparatus specially adapted for applying liquids or other fluent materials to finished paper or board, e.g. impregnating, coating
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/001—Modification of pulp properties
- D21C9/002—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives
- D21C9/004—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives inorganic compounds
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1026—Other features in bleaching processes
- D21C9/1047—Conserving the bleached pulp
Definitions
- This invention relates to processes for improving brightness and optical properties, preventing loss of brightness and for enhancing resistance to thermal yellowing in pulp and paper manufacture.
- Pulps produced by either mechanical or chemical pulping methods possess a color that can range from dark brown to creamish depending on the wood type and defibering process used.
- the pulp is bleached to produce white paper products for a multiplicity of applications.
- Bleaching is the removal or alteration of those light-absorbing substances found in unbleached pulp.
- the object is to decolorize the pulp without solubilizing the lignin.
- Either reducing (e.g. sodium hydrosulfite) or oxidizing (e.g., hydrogen peroxide) bleaching agents are usually used.
- the bleaching is often a multistage process.
- the bleaching of chemical pulps is an extension of the delignification that started in the digestion stage.
- the bleaching is often a multistage process, which stages may include chlorine dioxide bleaching, oxygen-alkaline delignification, and peroxide bleaching.
- Discoloration mostly ascribed to thermal aging, results in yellowing and brightness loss in various stages of papermaking processes employing bleached pulp and in the resultant paper products.
- the industry invests significantly in chemicals such as bleaching agents and optical brighteners that improve optical properties of the finished paper or paper products. To date, however, the results have been less than satisfactory and the economic losses resulting from discoloration and yellowing present significant ongoing challenges to the industry. Accordingly, there remains a need for a successful and practical solution to loss of brightness and undesirable yellowing of pulp and paper.
- WO 02/46522 teaches a process for final bleaching cellulose-containing pulp which has been subjected to previous bleaching with a peroxide compound. The process involves the sequential steps of exposing the pulp to an amount of a reducing agent in order to eliminate residual peroxide compound from the pulp and then final bleaching the pulp by exposing the pulp to an amount of formamidine sulfinic acid.
- WO 05/103135 teaches the treating of mechanical or chemical pulp with about 0.01 weight % to about 5 weight % of a mixture.
- the mixture is water, diethylenetriaminepentakis (methyl) phosphonic acid or its known salts, polyacrylic acid or its known salts, and optionally one or more inert compounds.
- the mixture acts to either maintain the brightness level of the pulp at the target level or to increase the brightness level of the pulp.
- the mixture allows for maintaining the pulp at the target level of brightness even when the amount of other ingredients, such as hydrogen peroxide, hydrosulfite, sodium silicate and magnesium, that are typically added to the pulp, are reduced.
- JP 09-049195 teaches a method whereby a stilbene-based fluorescent whitening agent is added to a raw pulp slurry together with a reducing agent such as sodium thiosulfate or sodium sulfite. The slurry is then subjected to a papermaking process.
- the reducing agent may be applied on the paper during papermaking but after the addition of the stilbene or it can be applied after the papermaking process.
- the method is directed to improving the photo yellowing stability of paper that contains optical brighteners.
- US 2002/059999 discloses a method for reducing or inhibiting alkaline darkening of mechanical pulp caused by the presence of calcium carbonate filler during production.
- the method comprises adding a sulfite, or sulfur-containing reducing agent, especially a sulfite to the mechanical pulp and the filler.
- the method is usefully applied in the production of mechanical pulp and paper in which calcium carbonate is used as a filler and also in the production of paper at neutral or mildly alkaline conditions.
- the present invention provides methods for improving and stabilizing brightness and enhancing resistance to yellowing in the papermaking process.
- this invention is a method of preparing a bleached pulp material having enhanced brightness and enhanced resistance to thermal yellowing comprising:
- the reducing agent, optical brighteners and optionally chelants may be used alone or in combination with known additives to enhance the quality of the desired paper product.
- the present invention provides an improved process for making paper and paper products exhibiting high optical brightness.
- Brightness stabilization against thermal yellowing, color improvement and brightness enhancement of bleached pulp and paper product prepared from the bleached pulp can be achieved by adding one or more reducing agents and one or more optical brighteners as defined herein to pulp, paper, paperboard or tissue anywhere in the papermaking process.
- Brightness is a term used to describe the whiteness of pulp or paper, on a scale from 0% (absolute black) to 100% (relative to a MgO standard, which has an absolute brightness of about 96%) by the reflectance of blue light (457 nm) from the paper.
- Thermal brightness loss is a brightness loss in paper and pulp under the influence of time, temperature and moisture (non-photochemical brightness loss).
- “Brightness loss during storage” is thermal brightness loss over time under storage conditions.
- Yellowing of a bleached pulp material is the loss of brightness of bleached pulp, paper, paperboard, paper tissue and related materials prepared from the bleached pulp over a period of time.
- bleached pulp material means bleached pulp and paper products prepared from the bleached pulp including paper, paperboard, tissue, and the like.
- Reducing Agents according to this invention include chemical substances capable of transform functional groups in the bleached pulp from a higher oxidation category to a lower oxidation category.
- the benefits of this transformation include increased brightness stability in the paper machine and enhanced performance of optical brighteners.
- the reducing agents are selected from the group consisting of sulfites, bisulfites, metabisulfites (pyrosulfites), sulfoxylates, thiosulfates, dithionites (hydrosulfites), polythionates, formamidinesulfinic acid and salts and derivatives thereof, formaldehyde bisulfite adduct and other aldehyde bisulfite adducts, sulfinamides and ethers of sulfinic acid, sulfenamides and ethers of sulfenic acid, sulfamides, phosphines, phosphonium salts, phosphites, and thiophosphites.
- sulfites means dibasic metal salts of sulfurous acid, H 2 SO 3 , including dibasic alkali and alkaline earth metal salts such as sodium sulfite (Na 2 SO 3 ), calcium sulfite (CaSO 3 ), and the like.
- “Bisulfites” means monobasic metal salts of sulfurous acid, H 2 SO 3 , including alkali and alkaline earth metal monobasic salts such as sodium bisulfite (NaHSO 3 ), magnesium bisulfite (Mg(HSO 3 ) 2 ), and the like.
- Sulfoxylates means salts of sulfoxylic acid, H 2 SO 2 , including zinc sulfoxylate (ZnSO 2 ), and the like.
- Metalbisulfites means salts of pyrosulfurous acid, H 2 S 2 O 5 , including sodium metabisulfite (Na 2 S 2 O 5 ), and the like.
- Thiosulfates means salts of thiosulfurous acid, H 2 S 2 O 3 , including potassium thiosulfate (Na 2 S 2 O 3 ), and the like.
- Dithionites hydrosulfites
- H 2 S 2 O 4 sodium dithionite (hydrosulfite) (Na 2 S 2 O 4 ), magnesium dithionite (MgS 2 O 4 ), and the like.
- Aldehyde bisulfite adducts means compounds of formula R1CH(OH)SO 3 H and metal salts thereof where R 1 is selected from alkyl, alkenyl, aryl and arylalkyl.
- Representative aldehyde bisulfite adducts include formaldehyde bisulfite adduct HOCH 2 SO 3 Na, and the like.
- Sulfenamides and ethers of sulfenic acid means compounds of formula R 1 -S-R 2 , where R 1 and R 2 are defined above.
- Representative sulfenamides include ethylsulfendimethylamide (CH 3 CH 2 SN(CH 3 ) 2 ), and the like.
- Phosphines means derivatives of phosphine, PH 3 , normally organic substituted phosphines of the formula R 6 R 7 R 8 P where R 6 -R 8 are independently selected from H, alkyl, alkenyl, aryl, arylalkyl and NR 4 R 5 where R 4 and R 5 is defined above.
- Representative phosphines include (HOCH 2 ) 3 P (THP), and the like.
- Phosphites means derivatives of phosphorous acid P(OH) 3 , including organic substituted phosphites of the formula (R 3 O)(R 4 O)(R 5 O)P where R 3 -R 5 are defined above.
- Representative phosphites include (CH 3 CH 2 O) 3 P, and the like.
- Thiophosphites means derivatives of phosphorothious acid HSP(OH) 2 , including organic substituted thiophosphites of formula (R 3 O)(R 4 O)(R 5 S)P where R 3 -R 5 are defined above.
- Representative thiophosphites include (CH 3 CH 2 O) 2 (CH 3 CH 2 S)P, and the like.
- Phosphonium salts means organic substituted phosphines of the formula R 1 R 3 R 4 R 5 P + X - , where R 1 and R 4 -R 5 are as defined above and X is any organic or inorganic anion.
- Representative phosphonium salts include (HO 2 CCH 2 CH 2 ) 3 P + HCr (THP), [(HOCH 2 ) 4 P + ] 2 (SO 4 ) 2- (BTHP), and the like.
- alkenyl means a monovalent group derived from a straight or branched hydrocarbon containing at least one carbon-carbon double bond by the removal of a single hydrogen atom.
- the alkenyl may be unsubstituted or substituted with one or more groups selected from amino, alkoxy, hydroxy and halogen.
- Alkoxy means an alkyl group attached to the parent molecular moiety through an oxygen atom. Representative alkoxy groups include methoxy, ethoxy, propoxy, butoxy, and the like. Methoxy and ethoxy are preferred.
- Alkyl means a monovalent group derived from a straight or branched chain saturated hydrocarbon by the removal of a single hydrogen atom.
- the alkyl may be unsubstituted or substituted with one or more groups selected from amino, alkoxy, hydroxy and halogen.
- Representative alkyl groups include methyl, ethyl, n- and iso -propyl, n -, sec -, iso - and tert -butyl, and the like.
- Alkylene means a divalent group derived from a straight or branched chain saturated hydrocarbon by the removal of two hydrogen atoms, for example methylene, 1,2-ethylene, 1,1-ethylene, 1,3-propylene, 2,2-dimethylpropylene, and the like.
- Amino means a group of formula -NY 1 Y 2 where Y 1 and Y 2 are independently selected from H, alkyl, alkenyl, aryl and arylalkyl. Representative amino groups include amino (-NH 2 ), methylamino, ethylamino, isopropylamino, diethylamino, dimethylamino, methylethylamino, and the like.
- Aryl means aromatic carbocyclic radicals and heterocyclic radicals having about 5 to about 14 ring atoms.
- the aryl may be unsubstituted or substituted with one or more groups selected from amino, alkoxy, hydroxy and halogen.
- Representative aryl include phenyl, naphthyl, phenanthryl, anthracyl, pyridyl, furyl, pyrrolyl, quinolyl, thienyl, thiazolyl, pyrimidyl, indolyl, and the like.
- Arylalkyl means an aryl group attached to the parent molecular moiety through an alkylene group.
- Representative arylalkyl groups include benzyl, 2-phenylethyl, and the like.
- Halo and halogen mean chlorine, fluorine, bromine and iodine.
- Salt means the metal, ammonium, substituted ammonium or phosphonium salt of an inorganic or organic anionic counterion.
- Representative metals include sodium, lithium, potassium, calcium, magnesium, and the like.
- Representative anionic counterions include sulfite, bisulfite, sulfoxylate, metabisulfite, thiosulfate, polythionate, hydrosulfite, formamidinesulfinate, and the like.
- the reducing agent is selected from the group consisting of substituted phosphines, sulfites, bisulfites and metabisulfites.
- the reducing agent is sodium bisulfite.
- the process of the present invention can be practiced on conventional papermaking equipment.
- papermaking equipment varies in operation and mechanical design, the processes by which paper is made on different equipment contain common stages.
- Papermaking typically includes a pulping stage, bleaching stage, stock preparation stage, a wet end stage and a dry end stage.
- cellulose fibers are liberated from a source of cellulose either by mechanical or chemical action, or both.
- Representative sources of cellulose include, but are not limited to, wood and similar "woody” plants, soy, rice, cotton, straw, flax, abaca, hemp, bagasse, lignin-containing plants, and the like, as well as original and recycled paper, paper tissue and paperboard.
- Such pulps include, but are not limited to, groundwood (GWD), bleached groundwood, thermomechanical pulps (TMP), bleached thermomechanical pulps, chemi-thermomechanical pulps (CTMP), bleached chemi-thermomechanical pulps, deinked pulps, kraft pulps, bleached kraft pulps, sulfite pulps, and bleached sulfite pulps.
- Recycled pulps may or may not be bleached in the recycling stage, but they are presumed to be originally bleached. Any of the pulps described above which have not previously been subjected to bleaching may be bleached as described herein to provide a bleached pulp material.
- the bleached pulp material is selected from the group consisting of virgin pulp, recycled pulp, kraft, sulfite pulp, mechanical pulp, any combination of such pulps, recycled paper, paper tissue, and any paper made from such listed pulps or combinations thereof.
- a further advantage of this invention is that it allows for substituting lower-priced mechanical pulp for higher priced kraft in printing grade kraft-mechanical paper.
- Use of the chemistry and methods described herein increases the brightness and stability toward yellowing, therefore permitting the use of higher amounts of mechanical pulp, with corresponding reduction in cost, without loss of quality in the resulting paper product.
- pulp is suspended in water in the stock preparation stage.
- Additives such as dyes, pigments, fillers, antimicrobial agents, defoamers, pH control agents and drainage aids also may be added to the stock at this stage.
- stock preparation includes such operations as dilution, screening and cleaning of the stock suspension that may occur prior to forming of the web.
- the wet end stage of the papermaking process comprises depositing the stock suspension or pulp slurry on the wire or felt of the papermaking machine to form a continuous web of fibers, draining of the web and consolidation of the web ("pressing") to form a sheet.
- Any papermaking machine known in the art is suitable for use with the process of the present invention. Such machines may include cylinder machines, fourdrinier machines, twin wire forming machines, tissue machines, and the like, and modifications thereof.
- the web is dried and may be subjected to additional processing like size pressing, calendering, spray coating with surface modifiers, printing, cutting, corrugating and the like.
- additional processing like size pressing, calendering, spray coating with surface modifiers, printing, cutting, corrugating and the like.
- the dried paper can be coated by spray coating using a sprayboom.
- one or more chelants are added to the bleached pulp or paper product.
- Suitable chelants according to this embodiment include compounds that are capable of chelating transitional metals that form colored products with pulp constituents and catalyze color-forming reactions in the bleached pulp or paper products.
- the chelant is a compound selected from the group consisting of organic phosphonate, phosphate, carboxylic acids, dithiocarbamates, salts of any of the previous members, and any combination thereof.
- Organic phosphonates means organic derivatives of phosphonic acid, HP(O)(OH) 2 , containing a single C-P bond, such as HEDP (CH 3 C(OH)(P(O)(OH) 2 ), 1-hydroxy-1,3-propanediylbis-phosphonic acid ((HO) 2 P(O)CH(OH)CH 2 CH 2 P(O)(OH) 2 )); preferably containing a single C-N bond adjacent (vicinal) to the C-P bond, such as DTMPA ((HO) 2 P(O)CH 2 N[CH 2 CH 2 N(CH 2 P(O)(OH) 2 ) 2 ] 2 ), AMP (N(CH 2 P(O)(OH) 2 ) 3 ), PAPEMP ((HO) 2 P(O)CH 2 ) 2 NCH(CH 3 )CH 2 (OCH 2 CH(CH 3 )) 2 N(CH 2 ) 6 N(CH 2 P(O)(OH) 2 ) 2 ),
- Organic phosphates means organic derivatives of phosphorous acid, P(O)(OH) 3 , containing a single C-P bond, including triethanolamine tri(phosphate ester) (N(CH 2 CH 2 OP(O)(OH) 2 ) 3 ), and the like.
- Carboxylic acids means organic compounds containing one or more carboxylic group(s), - C(O)OH, preferably aminocarboxylic acids containing a single C-N bond adjacent (vicinal) to the C-CO 2 bond, such as EDTA ((HO 2 CCH 2 ) 2 NCH 2 CH 2 N(CH 2 CO 2 H) 2 ), DTPA ((HO 2 CCH 2 ) 2 NCH 2 CH 2 N(CH 2 CO 2 H)CH 2 CH 2 N(CH 2 CO 2 H) 2 ), and the like and alkaline and alkaline earth metal salts thereof.
- EDTA ((HO 2 CCH 2 ) 2 NCH 2 CH 2 N(CH 2 CO 2 H) 2 )
- DTPA ((HO 2 CCH 2 ) 2 NCH 2 CH 2 N(CH 2 CO 2 H)CH 2 CH 2 N(CH 2 CO 2 H) 2 ), and the like and alkaline and alkaline earth metal salts thereof.
- Dithiocarbamates include monomeric dithiocarbamates, polymeric dithiocarbamates, polydiallylamine dithiocarbamates, 2,4,6-trimercapto-1,3,5-triazine, disodium ethylenebisdithiocarbamate, disodium dimethyldithiocarbamate, and the like.
- the chelant is a phosphonate.
- the phosphonate is diethylene-triamine-pentamethylene phosphonic acid (DTMPA) and salts thereof.
- DTMPA diethylene-triamine-pentamethylene phosphonic acid
- the chelant is a carboxylic acid.
- the carboxylate is selected from diethylenetriaminepentaacetic acid (DTPA) and salts thereof and ethylenediaminetetraacetic acid (EDTA) and salts thereof.
- DTPA diethylenetriaminepentaacetic acid
- EDTA ethylenediaminetetraacetic acid
- reducing agents used in combination with optical brighteners enhance the effect of optical brighteners (OBA).
- OBA's optical brighteners
- the reducing agents also improve the color scheme. This permits reduction of the amount of OBA's and brighteners such as blue dyes necessary to achieve comparable brightness and color.
- Replacing some of the OBA and dyes with reducing agents allows pulp and paper manufacturers to reduce production costs and reduce the overall amount of OBA and dyes present, while maintaining an acceptable level of brightness in the paper product and achieving the target color. In some cases it may be possible to eliminate dyes entirely and maintain color.
- one or more optical brighteners are added to the bleached pulp or paper product.
- Optical brighteners are fluorescent dyes or pigments that absorb ultraviolet radiation and reemit it at a higher frequency in the visible spectrum (blue), thereby effecting a white, bright appearance to the paper sheet when added to the stock furnish.
- Optical brighteners to be used according to the invention include azoles, biphenyls, coumarins; furans; naphthalimides; pyrazenes; and salts of such compounds including but not limited to alkali metal salts, alkaline earth metal salts, transition metal salts, organic salts and ammonium salts of such brightening agents; and combinations of one or more of the foregoing agents.
- the dosage of reducing agents and optical brighteners is the amount necessary to achieve the desired brightness and resistance to yellowing of the bleached pulp or paper product prepared from the bleached pulp and can be readily determined by one of skill in the art based on the characteristics of chelant or optical brightener, the pulp or paper being treated and the method of application.
- the effective amount of reducing agent added to the bleached pulp or paper product is the amount of reducing agent which enhances the brightness and resistance to thermal yellowing of the pulp or paper compared to pulp or paper which is not treated with the reducing agents. Methods for determining brightness and resistance to thermal yellowing are described herein.
- about 0.001 to about 1 preferably about 0.01 to about 0.1 weight percent of phosphonate, phosphate or carboxylic acid chelant and/or about 0.002 to about 0.02 weight percent of dithiocarbamates chelant based on oven-dried pulp may be added to the bleached pulp or paper product.
- Optical brighteners are typically added in amounts of about 0.005 to about 2, preferably 0.05 to about 1 weight percent of optical brightener based on oven-dried pulp.
- the reducing agents and optical brighteners can be added to bleached pulp or paper at any point in the papermaking or tissue making process.
- Representative addition points include, but are not limited to (a) to the pulp slurry in the latency chest; (b) to the pulp after the bleaching stage in a storage, blending or transfer chest; (c) to pulp after bleaching, washing and dewatering followed by cylinder or flash drying; (d) before or after the cleaners; (e) before or after the fan pump to the paper machine headbox; (f) to the paper machine white water; (g) to the silo or save all; (h) in the press section using, for example, a size press, coater or spray bar; (i) in the drying section using, for example, a size press, coater or spray bar; (j) on the calender using a wafer box; and/or (k) on paper in an off-machine coater or size press; and/or (1) in the curl control unit.
- the precise location where the reducing agents and optical brighteners should be added will depend on the specific equipment involved, the exact process conditions being used and the like. In some cases, the reducing agents and optical brighteners may be added at one or more locations for optimal effectiveness.
- Application can be by any means conventionally used in papermaking processes, including by "split-feeding" whereby a portion of the reducing agent and optical brightener is applied at one point in the papermaking process, for example on pulp or a wet sheet (before the dryers) and the remaining portion is added at a subsequent point, for example in the size press.
- the optical brightener can be added to the bleached pulp or paper product before, after or simultaneously with the reducing agent.
- the optical brightener may also be formulated with the reducing agent.
- one or more reducing agents and one or more optical brighteners are mixed with the surface sizing solution and applied in the size press.
- the reducing agent is added to bleached pulp after the bleaching stage in the storage, blending or transfer chest.
- the reducing agents and optical brighteners can also be added with a carrier or additive typically used in paper making, such as retention aids, sizing aids and solutions, starches, precipitated calcium carbonate, ground calcium carbonate, or other clays or fillers, and brightening additives.
- a carrier or additive typically used in paper making such as retention aids, sizing aids and solutions, starches, precipitated calcium carbonate, ground calcium carbonate, or other clays or fillers, and brightening additives.
- the reducing agents and optical brighteners are used in combination with one or more partially neutralized polycarboxylic acids, preferably polycarboxylic acids such as polyacrylic acid (CH 3 CH(CO 2 H)[CH 2 CH(CO 2 H)] n CH 2 CH 2 CO 2 H, where n is about 10 to about 50,000.
- the polycarboxylic acid may be neutralized to the target pH, (typically 5-6 as discussed below) with alkali such as sodium hydroxide.
- the reducing agents and optical brighteners may be used in addition to other additives conventionally used in papermaking to improve one or more properties of the finished paper product, assist in the process of manufacturing the paper itself, or both. These additives are generally characterized as either functional additives or control additives.
- Functional additives are typically those additives that are use to improve or impart certain specifically desired properties to the final paper product and include but are not limited to brightening agents, dyes, fillers, sizing agents, starches, and adhesives.
- Control additives are additives incorporated during the process of manufacturing the paper so as to improve the overall process without significantly affecting the physical properties of the paper.
- Control additives include biocides, retention aids, defoamers, pH control agents, pitch control agents, and drainage aids.
- Paper and paper products made using the process of the present invention may contain one or more functional additives and/or control additives.
- Pigments and dyes impart color to paper.
- Dyes include organic compounds having conjugated double bond systems; azo compounds; metallic azo compounds; anthraquinones; triaryl compounds, such as triarylmethane; quinoline and related compounds; acidic dyes (anionic organic dyes containing sulfonate groups, used with organic rations such as alum); basic dyes (cationic organic dyes containing amine functional groups); and direct dyes (acid-type dyes having high molecular weights and a specific, direct affinity for cellulose); as well as combinations of the above- listed suitable dye compounds.
- Pigments are finely divided mineral that can be either white or colored. The pigments that are most commonly used in the papermaking industry are clay, calcium carbonate and titanium dioxide.
- Fillers are added to paper to increase opacity and brightness.
- Fillers include but are not limited to calcium carbonate (calcite); precipitated calcium carbonate (PCC); calcium sulfate (including the various hydrated forms); calcium aluminate ; zinc oxides; magnesium silicates, such as talc; titanium dioxide (TiO 2 ) such as anatase or rutile ; clay, or kaolin, consisting of hydrated SiO 2 and Al 2 O 3 ; synthetic clay; mica; vermiculite; inorganic aggregates; perlite; sand; gravel; sandstone; glass beads; aerogels; xerogels ; seagel; fly ash; alumina; microspheres; hollow glass spheres; porous ceramic spheres; cork; seeds; lightweight polymers; xonotlite (a crystalline calcium silicate gel); pumice; exfoliated rock; waste concrete products; partially hydrated or unhydrated hydraulic cement particles; and diatomaceous earth, as well as combinations of such compounds
- Sizing agents are added to the paper during the manufacturing process to aid in the development of a resistance to penetration of liquids through the paper.
- Sizing agents can be internal sizing agents or external (surface) sizing agents, and can be used for hard-sizing, slack-sizing, or both methods of sizing.
- sizing agents include rosin; rosin precipitated with alum (Al 2 (SO 4 ) 3 ); abietic acid and abietic acid homologues such as neoabietic acid and levopimaric acid; stearic acid and stearic acid derivatives; ammonium zirconium carbonate; silicone and silicone- containing compounds, such as RE-29 available from GE-OSI and SM-8715, available from Dow Coming Corporation (Midland, MI); fluorochemicals of the general structure CF 3 (CF 2 ) n R, wherein R is anionic, cationic or another functional group, such as Gortex; alkylketene dimer (AKD), such as Aquapel 364, Aquapel (I 752, Heron) 70, Hercon 79, Precise 787, Precise 2000, and Precise 3000, all of which are commercially available from Hercules, Incorporated (Willmington, DE); and alkyl succinic an
- Starch has many uses in papermaking. For example, it functions as a retention agent, dry-strength agent and surface sizing agent.
- Starches include but are not limited to amylose ; amylopectin; starches containing various amounts of amylose and amylopectin, such as 25% amylose and 75% amylopectin (corn starch) and 20 % amylose and 80% amylopectin (potato starch); enzymatically treated starches; hydrolyzed starches ; heated starches, also known in the art as "pasted starches” ; cationic starches, such as those resulting from the reaction of a starch with a tertiary amine to form a quaternary ammonium salt; anionic starches; ampholytic starches (containing both cationic and anionic functionalities); cellulose and cellulose derived compounds; and combinations of these compounds.
- the method of this invention yields paper products with a bright surface.
- TMP thermomechanical pulp
- CTMP chemi-thermomechanical pulp
- RMP refiner mechanical pulp
- OBA optical brightener
- FAS formamidinesulfinic acid
- TCP for (HOCH 2 CH 2 ) 3 PHCl, tris-carboxyethylphosphonium hydrochloride
- BTHP for [(HOCH 2 ) 4 P] 2 (SO 4 ), tetra-hydroxymethylphosphonium sulfate
- THP for (HOCH 2 ) 3 P, tris-hydroxymethylphosphine
- EDTA for (HO 2 CCH 2 ) 2 NCH 2 CH 2 N(CH 2 CO 2 H) 2 , ethylenediaminetetraacetic acid
- DTPA for (HO 2 CCH 2 ) 2 NCH 2 CH 2 N(CH 2 CO 2 H)CH 2 CH 2 N(CH 2 CO 2 H) 2
- Handsheets were made of bleached pulp and then used in the experiments, in which the reducing agents were applied either on a wet sheet (before or after the press) before drum-drying or after drum-drying (temperature during drum drying: 100 °C).
- the third option was split-feed application.
- the surface sizing application was followed by one more round on a drum dryer.
- the load of the tested Agent or Composition solution was determined based on the dry weight of the pulp sample.
- the Agent or Composition solutions were applied using a rod, as uniformly as possible, as solutions in water.
- the test sheets were dried using a laboratory drum drier under uniform conditions (one round) and then, after measuring the brightness, subjected to the accelerated aging tests as described below.
- the 3x9 cm samples cut out of test sheets were kept in a water bath at 70 °C, 100% humidity for about 3 days. The samples were equilibrated in a constant humidity room before measuring brightness.
- the pulp samples (10% consistency, 5 g pulp on o.d. base) were sealed in plastic bags and kept in a water bath at 70 °C for 3-6 hours. Handsheets were prepared and equilibrated in a constant humidity room before measuring brightness.
- the chemicals were added directly to the pulp (thin stock or thick stock) and mixed with the pulp in sealed bags.
- a pulp application procedure for OBA enhancement the chemicals were added directly to the bleached kraft pulp at 20% consistency, mixed with the pulp in sealed bags and kept at 45-80 °C for 30 min.
- the pulp was diluted to 5% consistency, the OBA was added, mixed with the pulp, and the slurry was kept at 50 °C for 20 min. Then the slurry was further diluted and hand sheets prepared according to the standard procedure.
- compositions were tested and gave good results in laboratory simulation of the PM application.
- the chemicals (compositions) not listed in Table 1 were applied as 40% solutions.
- Table 3 Mixed Kraft-CTMP 1, headbox, surface application with starch (surface sizing solution) on both sides # Treatment Br 1 Control 94.34 2 0.27% Sodium Metabisulfite 96.17
- Table 4 Mixed Kraft-CTMP 2, headbox, surface application with starch (surface sizing solution) on both sides # Treatment Br 1 Control 94.93 2 0.27% Sodium Metabisulfite 95.63
- Table 5 Mixed kraft-CTMP 3, headbox # Treatment Br Gain vs. Control Gain vs.
- Tables 3-8 illustrate the effect of a reducing agent sodium bisulfite (metabisulfite) and a brightness enhancing composition on paper brightness: the reducing agent improves brightness (Tables 3-8), partially compensating for the brightness loss in the dryer (Table 8). The chemistry further more improves brightness in presence of an OBA (Table 5).
- Tables 9-11 demonstrate the effect of reducing chemicals other than sodium metabisulfite, such as FAS and phosphorous (III) compounds.
- Control Synergism 1 Control 85.48 0 N/A 2 0.2% Composition C 86.79 1.35 N/A 3 0.2% OBA 89.7 4.21 N/A 4 0.35% OBA 90.73 5.22 N/A 5 0.1% Composition C 86.34 0.81 N/A 6 0.2% OBA + 0.2% Composition C 91.4 5.82 0.26 7 0.2% OBA + 0.1% Composition C 90.78 5.25 0.23 8 0.35% OBA + 0.2% Composition C 92.55 6.87 0.30 9 0.35% OBA + 0.1% Composition C 92.06 6.54 0.51 Table 14 Activation of an optical brightener: kraft pulp 4, Composition C (0, 0.2%) with OBA (0, 0.2%) Br vs.(0,0) OBA1 C0, OBA0 78.24 0 C0, OBA0.2 79.74 1.5 C0.2, OBA0 80.43 2.19 C0.2, OBA0.2 82.53 4.29 Synergism 0.6 Table 15 Mixed kraft-CT
- Intensity Control 33746 0.2% Composition A 36149 0.35% OBA 106233 0.1% Composition A + 0.35% OBA 111609 0.2% Composition A + 0.35% OBA 116373 0.3% Composition A + 0.35% OBA 119845 Table 16 Kraft headbox containing OBA, activation of an optical brightener as measured by fluorescence intensities: Sample Fluoresc.
- Tables 12-27 illustrate application of compositions where a reducing agent is combined with chelant(s). Different combinations can be compared (all effective). The formulations improve long-term brightness stability of paper toward thermal aging (Tables 24-27). This set of data also demonstrates an OBA activation by the compositions (Tables 12-14, 25). Applying the formulation allows cutting the dose of an optical brightener. Tables 16 and 17 illustrate the effect of the formulation on fluorescence.
- Control 1 0 0 86.64 0.00 2 0.5 0.5 91.66 5.02 3 0.5 0.25 90.69 4.05 4 0.25 0.25 89.32 2.68 5 0 0.5 89.00 2.36 6 0.5 0 87.68 1.04 Table 30 Kraft 6, activation of an optical brightener as measured by fluorescence intensities: Sample Fluoresc. Intensity Control 7871 0.5% Composition G 10370 0.5% OBA 128578 0.5% Composition G, then 0.5% OBA 201199 0.25% Composition G, then 0.5% OBA 161354 0.5% Composition G, then 0.25% OBA 157359 0.5% Composition A, then 0.5% OBA 191759
- Tables 28-30 illustrate activation of an OBA via prior application of a composition.
- Tables 31-33 illustrate brightness recovery and long-term stabilization upon application of the proposed formulations.
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Description
- This invention relates to processes for improving brightness and optical properties, preventing loss of brightness and for enhancing resistance to thermal yellowing in pulp and paper manufacture.
- Pulps produced by either mechanical or chemical pulping methods possess a color that can range from dark brown to creamish depending on the wood type and defibering process used. The pulp is bleached to produce white paper products for a multiplicity of applications.
- Bleaching is the removal or alteration of those light-absorbing substances found in unbleached pulp. In the bleaching of mechanical pulp, the object is to decolorize the pulp without solubilizing the lignin. Either reducing (e.g. sodium hydrosulfite) or oxidizing (e.g., hydrogen peroxide) bleaching agents are usually used. The bleaching is often a multistage process. The bleaching of chemical pulps is an extension of the delignification that started in the digestion stage. The bleaching is often a multistage process, which stages may include chlorine dioxide bleaching, oxygen-alkaline delignification, and peroxide bleaching.
- Discoloration, mostly ascribed to thermal aging, results in yellowing and brightness loss in various stages of papermaking processes employing bleached pulp and in the resultant paper products. The industry invests significantly in chemicals such as bleaching agents and optical brighteners that improve optical properties of the finished paper or paper products. To date, however, the results have been less than satisfactory and the economic losses resulting from discoloration and yellowing present significant ongoing challenges to the industry. Accordingly, there remains a need for a successful and practical solution to loss of brightness and undesirable yellowing of pulp and paper.
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WO 02/46522 -
WO 05/103135 -
JP 09-049195 -
US 2002/059999 discloses a method for reducing or inhibiting alkaline darkening of mechanical pulp caused by the presence of calcium carbonate filler during production. The method comprises adding a sulfite, or sulfur-containing reducing agent, especially a sulfite to the mechanical pulp and the filler. The method is usefully applied in the production of mechanical pulp and paper in which calcium carbonate is used as a filler and also in the production of paper at neutral or mildly alkaline conditions. - The present invention provides methods for improving and stabilizing brightness and enhancing resistance to yellowing in the papermaking process.
- In an aspect, this invention is a method of preparing a bleached pulp material having enhanced brightness and enhanced resistance to thermal yellowing comprising:
- i) providing bleached pulp material;
- ii) contacting the bleached pulp material with an effective amount of one or more reducing agents which enhances the brightness and resistance to thermal yellowing of the pulp compared to pulp which is not treated with the reducing agent(s), and
- iii) contacting the bleached pulp material with one or more optical brighteners selected from the group consisting of azoles, biphenyls, coumarins; furans; naphthalimides; pyrazenes; and salts of such compounds including alkali metal salts, alkaline earth metal salts, transition metal salts, organic salts and ammonium salts; and combinations thereof.
- Applicant has discovered that reducing agents used in combination with optical brighteners enhance the effect of the optical brighteners and improve color scheme.
- The reducing agent, optical brighteners and optionally chelants may be used alone or in combination with known additives to enhance the quality of the desired paper product.
- The present invention provides an improved process for making paper and paper products exhibiting high optical brightness. Brightness stabilization against thermal yellowing, color improvement and brightness enhancement of bleached pulp and paper product prepared from the bleached pulp can be achieved by adding one or more reducing agents and one or more optical brighteners as defined herein to pulp, paper, paperboard or tissue anywhere in the papermaking process.
- Brightness is a term used to describe the whiteness of pulp or paper, on a scale from 0% (absolute black) to 100% (relative to a MgO standard, which has an absolute brightness of about 96%) by the reflectance of blue light (457 nm) from the paper. "Thermal brightness loss" is a brightness loss in paper and pulp under the influence of time, temperature and moisture (non-photochemical brightness loss). "Brightness loss during storage" is thermal brightness loss over time under storage conditions.
- Yellowing of a bleached pulp material (brightness reversion) is the loss of brightness of bleached pulp, paper, paperboard, paper tissue and related materials prepared from the bleached pulp over a period of time.
- The reducing agents described herein are suitable for use on any bleached pulp material used in papermaking processes and any paper product prepared from the bleached pulp. As used herein, "bleached pulp material" means bleached pulp and paper products prepared from the bleached pulp including paper, paperboard, tissue, and the like.
- Reducing Agents according to this invention include chemical substances capable of transform functional groups in the bleached pulp from a higher oxidation category to a lower oxidation category. The benefits of this transformation include increased brightness stability in the paper machine and enhanced performance of optical brighteners.
- In an embodiment, the reducing agents are selected from the group consisting of sulfites, bisulfites, metabisulfites (pyrosulfites), sulfoxylates, thiosulfates, dithionites (hydrosulfites), polythionates, formamidinesulfinic acid and salts and derivatives thereof, formaldehyde bisulfite adduct and other aldehyde bisulfite adducts, sulfinamides and ethers of sulfinic acid, sulfenamides and ethers of sulfenic acid, sulfamides, phosphines, phosphonium salts, phosphites, and thiophosphites.
- As used herein, "sulfites" means dibasic metal salts of sulfurous acid, H2SO3, including dibasic alkali and alkaline earth metal salts such as sodium sulfite (Na2SO3), calcium sulfite (CaSO3), and the like.
- "Bisulfites" means monobasic metal salts of sulfurous acid, H2SO3, including alkali and alkaline earth metal monobasic salts such as sodium bisulfite (NaHSO3), magnesium bisulfite (Mg(HSO3)2), and the like.
- "Sulfoxylates" means salts of sulfoxylic acid, H2SO2, including zinc sulfoxylate (ZnSO2), and the like.
- "Metabisulfites (Pyrosulfites)" means salts of pyrosulfurous acid, H2S2O5, including sodium metabisulfite (Na2S2O5), and the like.
- "Thiosulfates" means salts of thiosulfurous acid, H2S2O3, including potassium thiosulfate (Na2S2O3), and the like.
- "Polythionates" means salts of polythionic acid, H2SnO6 (n=2-6), including sodium trithionate (Na2S3O6), salts of dithionic acid, H2S2O6, such as sodium dithionate Na2S2O6, and the like.
- "Dithionites (hydrosulfites)" means salts of dithionous (hydrosulfurous, hyposulfurous) acid, H2S2O4, including sodium dithionite (hydrosulfite) (Na2S2O4), magnesium dithionite (MgS2O4), and the like.
- "Formamidinesulfinic acid (FAS)" means a compound of formula H2NC(=NH)SO2H and its salts and derivatives including the sodium salt H2NC(=NH)SO2Na.
- "Aldehyde bisulfite adducts" means compounds of formula R1CH(OH)SO3H and metal salts thereof where R1 is selected from alkyl, alkenyl, aryl and arylalkyl. Representative aldehyde bisulfite adducts include formaldehyde bisulfite adduct HOCH2SO3Na, and the like.
- "Sulfinamides and ethers of sulfinic acid" means compounds of formula R1-S(=O)-R2, where R1 is defined herein and R2 is selected from OR3 and NR4R5, where R3-R5 are independently selected from selected from alkyl, alkenyl, aryl and arylalkyl. Representative sulfinamides include ethylsulfindimethylamide (CH3CH2S(=O)N(CH3)2), and the like.
- "Sulfenamides and ethers of sulfenic acid" means compounds of formula R1-S-R2, where R1 and R2 are defined above. Representative sulfenamides include ethylsulfendimethylamide (CH3CH2SN(CH3)2), and the like.
- "Sulfamides" means compounds of formula R1-C(=S)-NR4R5, where R1, R4 and R5 are defined above. Representative sulfamides include CH3CH2C(=S)N(CH3)2, and the like.
- "Phosphines" means derivatives of phosphine, PH3, normally organic substituted phosphines of the formula R6R7R8P where R6-R8 are independently selected from H, alkyl, alkenyl, aryl, arylalkyl and NR4R5 where R4 and R5 is defined above. Representative phosphines include (HOCH2)3P (THP), and the like.
- "Phosphites" means derivatives of phosphorous acid P(OH)3, including organic substituted phosphites of the formula (R3O)(R4O)(R5O)P where R3-R5 are defined above. Representative phosphites include (CH3CH2O)3P, and the like.
- "Thiophosphites" means derivatives of phosphorothious acid HSP(OH)2, including organic substituted thiophosphites of formula (R3O)(R4O)(R5S)P where R3-R5 are defined above. Representative thiophosphites include (CH3CH2O)2(CH3CH2S)P, and the like.
- "Phosphonium salts" means organic substituted phosphines of the formula R1R3R4R5P+X-, where R1 and R4-R5 are as defined above and X is any organic or inorganic anion. Representative phosphonium salts include (HO2CCH2CH2)3P+HCr (THP), [(HOCH2)4P+]2(SO4)2- (BTHP), and the like.
- "Alkenyl" means a monovalent group derived from a straight or branched hydrocarbon containing at least one carbon-carbon double bond by the removal of a single hydrogen atom. The alkenyl may be unsubstituted or substituted with one or more groups selected from amino, alkoxy, hydroxy and halogen.
- "Alkoxy" means an alkyl group attached to the parent molecular moiety through an oxygen atom. Representative alkoxy groups include methoxy, ethoxy, propoxy, butoxy, and the like. Methoxy and ethoxy are preferred.
- "Alkyl" means a monovalent group derived from a straight or branched chain saturated hydrocarbon by the removal of a single hydrogen atom. The alkyl may be unsubstituted or substituted with one or more groups selected from amino, alkoxy, hydroxy and halogen. Representative alkyl groups include methyl, ethyl, n- and iso-propyl, n-, sec-, iso- and tert-butyl, and the like.
- "Alkylene" means a divalent group derived from a straight or branched chain saturated hydrocarbon by the removal of two hydrogen atoms, for example methylene, 1,2-ethylene, 1,1-ethylene, 1,3-propylene, 2,2-dimethylpropylene, and the like.
- "Amino" means a group of formula -NY1Y2 where Y1 and Y2 are independently selected from H, alkyl, alkenyl, aryl and arylalkyl. Representative amino groups include amino (-NH2), methylamino, ethylamino, isopropylamino, diethylamino, dimethylamino, methylethylamino, and the like.
- "Aryl" means aromatic carbocyclic radicals and heterocyclic radicals having about 5 to about 14 ring atoms. The aryl may be unsubstituted or substituted with one or more groups selected from amino, alkoxy, hydroxy and halogen. Representative aryl include phenyl, naphthyl, phenanthryl, anthracyl, pyridyl, furyl, pyrrolyl, quinolyl, thienyl, thiazolyl, pyrimidyl, indolyl, and the like.
- "Arylalkyl" means an aryl group attached to the parent molecular moiety through an alkylene group. Representative arylalkyl groups include benzyl, 2-phenylethyl, and the like.
- "Halo" and "halogen" mean chlorine, fluorine, bromine and iodine.
- "Salt" means the metal, ammonium, substituted ammonium or phosphonium salt of an inorganic or organic anionic counterion. Representative metals include sodium, lithium, potassium, calcium, magnesium, and the like. Representative anionic counterions include sulfite, bisulfite, sulfoxylate, metabisulfite, thiosulfate, polythionate, hydrosulfite, formamidinesulfinate, and the like.
- In an embodiment, the reducing agent is selected from the group consisting of substituted phosphines, sulfites, bisulfites and metabisulfites.
- In an embodiment, the reducing agent is sodium bisulfite.
- The process of the present invention can be practiced on conventional papermaking equipment. Although papermaking equipment varies in operation and mechanical design, the processes by which paper is made on different equipment contain common stages. Papermaking typically includes a pulping stage, bleaching stage, stock preparation stage, a wet end stage and a dry end stage.
- In the pulping stage, individual cellulose fibers are liberated from a source of cellulose either by mechanical or chemical action, or both. Representative sources of cellulose include, but are not limited to, wood and similar "woody" plants, soy, rice, cotton, straw, flax, abaca, hemp, bagasse, lignin-containing plants, and the like, as well as original and recycled paper, paper tissue and paperboard. Such pulps include, but are not limited to, groundwood (GWD), bleached groundwood, thermomechanical pulps (TMP), bleached thermomechanical pulps, chemi-thermomechanical pulps (CTMP), bleached chemi-thermomechanical pulps, deinked pulps, kraft pulps, bleached kraft pulps, sulfite pulps, and bleached sulfite pulps. Recycled pulps may or may not be bleached in the recycling stage, but they are presumed to be originally bleached. Any of the pulps described above which have not previously been subjected to bleaching may be bleached as described herein to provide a bleached pulp material.
- In an embodiment, the bleached pulp material is selected from the group consisting of virgin pulp, recycled pulp, kraft, sulfite pulp, mechanical pulp, any combination of such pulps, recycled paper, paper tissue, and any paper made from such listed pulps or combinations thereof.
- A further advantage of this invention is that it allows for substituting lower-priced mechanical pulp for higher priced kraft in printing grade kraft-mechanical paper. Use of the chemistry and methods described herein increases the brightness and stability toward yellowing, therefore permitting the use of higher amounts of mechanical pulp, with corresponding reduction in cost, without loss of quality in the resulting paper product.
- The pulp is suspended in water in the stock preparation stage. Additives such as dyes, pigments, fillers, antimicrobial agents, defoamers, pH control agents and drainage aids also may be added to the stock at this stage. As the term is used in this disclosure, "stock preparation" includes such operations as dilution, screening and cleaning of the stock suspension that may occur prior to forming of the web.
- The wet end stage of the papermaking process comprises depositing the stock suspension or pulp slurry on the wire or felt of the papermaking machine to form a continuous web of fibers, draining of the web and consolidation of the web ("pressing") to form a sheet. Any papermaking machine known in the art is suitable for use with the process of the present invention. Such machines may include cylinder machines, fourdrinier machines, twin wire forming machines, tissue machines, and the like, and modifications thereof.
- In the dry end stage of the papermaking process, the web is dried and may be subjected to additional processing like size pressing, calendering, spray coating with surface modifiers, printing, cutting, corrugating and the like. In addition to a size press and calender waterbox, the dried paper can be coated by spray coating using a sprayboom.
- In an embodiment, one or more chelants are added to the bleached pulp or paper product. Suitable chelants according to this embodiment include compounds that are capable of chelating transitional metals that form colored products with pulp constituents and catalyze color-forming reactions in the bleached pulp or paper products.
- In an embodiment, the chelant is a compound selected from the group consisting of organic phosphonate, phosphate, carboxylic acids, dithiocarbamates, salts of any of the previous members, and any combination thereof.
- "Organic phosphonates" means organic derivatives of phosphonic acid, HP(O)(OH)2, containing a single C-P bond, such as HEDP (CH3C(OH)(P(O)(OH)2), 1-hydroxy-1,3-propanediylbis-phosphonic acid ((HO)2P(O)CH(OH)CH2CH2P(O)(OH)2)); preferably containing a single C-N bond adjacent (vicinal) to the C-P bond, such as DTMPA ((HO)2P(O)CH2N[CH2CH2N(CH2P(O)(OH)2)2]2), AMP (N(CH2P(O)(OH)2)3), PAPEMP ((HO)2P(O)CH2)2NCH(CH3)CH2(OCH2CH(CH3))2N(CH2)6N(CH2P(O)(OH)2)2), HMDTMP ((HO)2P(O)CH2)2N(CH2)6N(CH2P(O)(OH)2)2), HEBMP (N(CH2P(O)(OH)2)2CH2CH2OH), and the like.
- "Organic phosphates" means organic derivatives of phosphorous acid, P(O)(OH)3, containing a single C-P bond, including triethanolamine tri(phosphate ester) (N(CH2CH2OP(O)(OH)2)3), and the like.
- "Carboxylic acids" means organic compounds containing one or more carboxylic group(s), - C(O)OH, preferably aminocarboxylic acids containing a single C-N bond adjacent (vicinal) to the C-CO2 bond, such as EDTA ((HO2CCH2)2NCH2CH2N(CH2CO2H)2), DTPA ((HO2CCH2)2NCH2CH2N(CH2CO2H)CH2CH2N(CH2CO2H)2), and the like and alkaline and alkaline earth metal salts thereof.
- "Dithiocarbamates" include monomeric dithiocarbamates, polymeric dithiocarbamates, polydiallylamine dithiocarbamates, 2,4,6-trimercapto-1,3,5-triazine, disodium ethylenebisdithiocarbamate, disodium dimethyldithiocarbamate, and the like.
- In an embodiment, the chelant is a phosphonate.
- In an embodiment, the phosphonate is diethylene-triamine-pentamethylene phosphonic acid (DTMPA) and salts thereof.
- In an embodiment, the chelant is a carboxylic acid.
- In an embodiment, the carboxylate is selected from diethylenetriaminepentaacetic acid (DTPA) and salts thereof and ethylenediaminetetraacetic acid (EDTA) and salts thereof.
- Applicant has discovered that reducing agents used in combination with optical brighteners ("OBA's") enhance the effect of optical brighteners (OBA). The reducing agents also improve the color scheme. This permits reduction of the amount of OBA's and brighteners such as blue dyes necessary to achieve comparable brightness and color. Replacing some of the OBA and dyes with reducing agents allows pulp and paper manufacturers to reduce production costs and reduce the overall amount of OBA and dyes present, while maintaining an acceptable level of brightness in the paper product and achieving the target color. In some cases it may be possible to eliminate dyes entirely and maintain color.
- Accordingly, one or more optical brighteners ("OBA's") are added to the bleached pulp or paper product.
- "Optical brighteners" are fluorescent dyes or pigments that absorb ultraviolet radiation and reemit it at a higher frequency in the visible spectrum (blue), thereby effecting a white, bright appearance to the paper sheet when added to the stock furnish. Optical brighteners to be used according to the invention include azoles, biphenyls, coumarins; furans; naphthalimides; pyrazenes; and salts of such compounds including but not limited to alkali metal salts, alkaline earth metal salts, transition metal salts, organic salts and ammonium salts of such brightening agents; and combinations of one or more of the foregoing agents.
- The dosage of reducing agents and optical brighteners is the amount necessary to achieve the desired brightness and resistance to yellowing of the bleached pulp or paper product prepared from the bleached pulp and can be readily determined by one of skill in the art based on the characteristics of chelant or optical brightener, the pulp or paper being treated and the method of application.
- The effective amount of reducing agent added to the bleached pulp or paper product is the amount of reducing agent which enhances the brightness and resistance to thermal yellowing of the pulp or paper compared to pulp or paper which is not treated with the reducing agents. Methods for determining brightness and resistance to thermal yellowing are described herein.
- Typically, about 0.005 to about 2, preferably about 0.05 to about 0.25 weight percent, based on oven-dried pulp of reducing agent is added to the bleached pulp or paper product.
- In a typical application, about 0.001 to about 1, preferably about 0.01 to about 0.1 weight percent of phosphonate, phosphate or carboxylic acid chelant and/or about 0.002 to about 0.02 weight percent of dithiocarbamates chelant based on oven-dried pulp may be added to the bleached pulp or paper product.
- Optical brighteners are typically added in amounts of about 0.005 to about 2, preferably 0.05 to about 1 weight percent of optical brightener based on oven-dried pulp.
- The reducing agents and optical brighteners can be added to bleached pulp or paper at any point in the papermaking or tissue making process. Representative addition points include, but are not limited to (a) to the pulp slurry in the latency chest; (b) to the pulp after the bleaching stage in a storage, blending or transfer chest; (c) to pulp after bleaching, washing and dewatering followed by cylinder or flash drying; (d) before or after the cleaners; (e) before or after the fan pump to the paper machine headbox; (f) to the paper machine white water; (g) to the silo or save all; (h) in the press section using, for example, a size press, coater or spray bar; (i) in the drying section using, for example, a size press, coater or spray bar; (j) on the calender using a wafer box; and/or (k) on paper in an off-machine coater or size press; and/or (1) in the curl control unit.
- The precise location where the reducing agents and optical brighteners should be added will depend on the specific equipment involved, the exact process conditions being used and the like. In some cases, the reducing agents and optical brighteners may be added at one or more locations for optimal effectiveness.
- Application can be by any means conventionally used in papermaking processes, including by "split-feeding" whereby a portion of the reducing agent and optical brightener is applied at one point in the papermaking process, for example on pulp or a wet sheet (before the dryers) and the remaining portion is added at a subsequent point, for example in the size press.
- The optical brightener can be added to the bleached pulp or paper product before, after or simultaneously with the reducing agent. The optical brightener may also be formulated with the reducing agent.
- In an embodiment, one or more reducing agents and one or more optical brighteners are mixed with the surface sizing solution and applied in the size press.
- In an embodiment, the reducing agent is added to bleached pulp after the bleaching stage in the storage, blending or transfer chest.
- At these various locations, the reducing agents and optical brighteners can also be added with a carrier or additive typically used in paper making, such as retention aids, sizing aids and solutions, starches, precipitated calcium carbonate, ground calcium carbonate, or other clays or fillers, and brightening additives.
- In an embodiment, the reducing agents and optical brighteners are used in combination with one or more partially neutralized polycarboxylic acids, preferably polycarboxylic acids such as polyacrylic acid (CH3CH(CO2H)[CH2CH(CO2H)]nCH2CH2CO2H, where n is about 10 to about 50,000. The polycarboxylic acid may be neutralized to the target pH, (typically 5-6 as discussed below) with alkali such as sodium hydroxide.
- The reducing agents and optical brighteners may be used in addition to other additives conventionally used in papermaking to improve one or more properties of the finished paper product, assist in the process of manufacturing the paper itself, or both. These additives are generally characterized as either functional additives or control additives.
- Functional additives are typically those additives that are use to improve or impart certain specifically desired properties to the final paper product and include but are not limited to brightening agents, dyes, fillers, sizing agents, starches, and adhesives.
- Control additives, on the other hand, are additives incorporated during the process of manufacturing the paper so as to improve the overall process without significantly affecting the physical properties of the paper. Control additives include biocides, retention aids, defoamers, pH control agents, pitch control agents, and drainage aids. Paper and paper products made using the process of the present invention may contain one or more functional additives and/or control additives.
- Pigments and dyes impart color to paper. Dyes include organic compounds having conjugated double bond systems; azo compounds; metallic azo compounds; anthraquinones; triaryl compounds, such as triarylmethane; quinoline and related compounds; acidic dyes (anionic organic dyes containing sulfonate groups, used with organic rations such as alum); basic dyes (cationic organic dyes containing amine functional groups); and direct dyes (acid-type dyes having high molecular weights and a specific, direct affinity for cellulose); as well as combinations of the above- listed suitable dye compounds. Pigments are finely divided mineral that can be either white or colored. The pigments that are most commonly used in the papermaking industry are clay, calcium carbonate and titanium dioxide.
- Fillers are added to paper to increase opacity and brightness. Fillers include but are not limited to calcium carbonate (calcite); precipitated calcium carbonate (PCC); calcium sulfate (including the various hydrated forms); calcium aluminate ; zinc oxides; magnesium silicates, such as talc; titanium dioxide (TiO2) such as anatase or rutile ; clay, or kaolin, consisting of hydrated SiO2 and Al2O3; synthetic clay; mica; vermiculite; inorganic aggregates; perlite; sand; gravel; sandstone; glass beads; aerogels; xerogels ; seagel; fly ash; alumina; microspheres; hollow glass spheres; porous ceramic spheres; cork; seeds; lightweight polymers; xonotlite (a crystalline calcium silicate gel); pumice; exfoliated rock; waste concrete products; partially hydrated or unhydrated hydraulic cement particles; and diatomaceous earth, as well as combinations of such compounds.
- Sizing agents are added to the paper during the manufacturing process to aid in the development of a resistance to penetration of liquids through the paper. Sizing agents can be internal sizing agents or external (surface) sizing agents, and can be used for hard-sizing, slack-sizing, or both methods of sizing. More specifically, sizing agents include rosin; rosin precipitated with alum (Al2(SO4)3); abietic acid and abietic acid homologues such as neoabietic acid and levopimaric acid; stearic acid and stearic acid derivatives; ammonium zirconium carbonate; silicone and silicone- containing compounds, such as RE-29 available from GE-OSI and SM-8715, available from Dow Coming Corporation (Midland, MI); fluorochemicals of the general structure CF3(CF2)nR, wherein R is anionic, cationic or another functional group, such as Gortex; alkylketene dimer (AKD), such as Aquapel 364, Aquapel (I 752, Heron) 70, Hercon 79, Precise 787, Precise 2000, and Precise 3000, all of which are commercially available from Hercules, Incorporated (Willmington, DE); and alkyl succinic anhydride (ASA); emulsions of ASA or AKD with cationic starch; ASA incorporating alum; starch; hydroxymethyl starch; carboxymethylcellulose (CMC) ; polyvinyl alcohol; methyl cellulose; alginates; waxes; wax emulsions; and combinations of such sizing agents.
- Starch has many uses in papermaking. For example, it functions as a retention agent, dry-strength agent and surface sizing agent. Starches include but are not limited to amylose ; amylopectin; starches containing various amounts of amylose and amylopectin, such as 25% amylose and 75% amylopectin (corn starch) and 20 % amylose and 80% amylopectin (potato starch); enzymatically treated starches; hydrolyzed starches ; heated starches, also known in the art as "pasted starches" ; cationic starches, such as those resulting from the reaction of a starch with a tertiary amine to form a quaternary ammonium salt; anionic starches; ampholytic starches (containing both cationic and anionic functionalities); cellulose and cellulose derived compounds; and combinations of these compounds.
- The method of this invention yields paper products with a bright surface.
- The foregoing may be better understood by reference to the following examples, which are presented for purposes of illustration and are not intended to limit the scope of the invention.
Table 1 Representative Compositions (water not included) Component % Component Composition A DTMPA 7.6 Sodium polyacrylate 3.5 NaOH 1.5 Sodium Metabisulfite 26.6 Composition B DTMPA 9.0 NaOH 3.6 Sodium Metabisulfite 27 Composition C DTMPA 6.0 NaOH 3.0 Sodium Metabisulfite 30 Composition D DTMPA 5.0 DTPA 4.1 NaOH 1.5 Sodium Metabisulfite 30 Composition E DTMPA 7.4 NaOH 5.5 Sodium Metabisulfite 16.7 FAS 7.7 Composition F DTMPA 4.2 NaOH 2.8 Sodium Metabisulfite 19.9 THPS 9.8 DTPA 4.1 NaNO2 0.1 Composition G DTPA 2.9 Sodium polyacrylate 1.0 NaOH 1.3 Sodium Metabisulfite 30.0 - In these Examples, sufficient 50% aqueous sodium hydroxide was added to achieve appropriate pH for the agent or composition being tested. All percentages in these examples are given on a weight percent dry pulp basis.
- In these Examples, the following terms shall have the indicated meaning.
Br for ISO brightness R457 (TAPPI 525); Ye for E313 yellowness; Im Br for R457 brightness after the application; TA Br for R457 brightness after thermal aging; TA loss for loss in brightness after thermal aging; % Inh. for % Inhibition of brightness loss: %Inh. = 100-100*(ImBr-TABr)/(ImBr-TABr)control; WI for E313 Whiteness: TMP for thermomechanical pulp; CTMP for chemi-thermomechanical pulp; RMP for refiner mechanical pulp; OBA for optical brightener; FAS for formamidinesulfinic acid; TCP for (HOCH2CH2)3PHCl, tris-carboxyethylphosphonium hydrochloride; BTHP for [(HOCH2)4P]2(SO4), tetra-hydroxymethylphosphonium sulfate; THP for (HOCH2)3P, tris-hydroxymethylphosphine; EDTA for (HO2CCH2)2NCH2CH2N(CH2CO2H)2, ethylenediaminetetraacetic acid; DTPA for (HO2CCH2)2NCH2CH2N(CH2CO2H)CH2CH2N(CH2CO2H)2, diethylenetriaminepentaacetic acid; DTMPA for H2O3PCH2N[CH2CH2N(CH2PO3H2)2]2, diethylene-triamine-pentamethylene phosphonic acid; and DTC for sodium dimethyldithiocarbamate. - Handsheets were made of bleached pulp and then used in the experiments, in which the reducing agents were applied either on a wet sheet (before or after the press) before drum-drying or after drum-drying (temperature during drum drying: 100 °C). The third option was split-feed application. The surface sizing application was followed by one more round on a drum dryer.
- The load of the tested Agent or Composition solution was determined based on the dry weight of the pulp sample. The Agent or Composition solutions were applied using a rod, as uniformly as possible, as solutions in water. The test sheets were dried using a laboratory drum drier under uniform conditions (one round) and then, after measuring the brightness, subjected to the accelerated aging tests as described below.
- The 3x9 cm samples cut out of test sheets were kept in a water bath at 70 °C, 100% humidity for about 3 days. The samples were equilibrated in a constant humidity room before measuring brightness.
- The pulp samples (10% consistency, 5 g pulp on o.d. base) were sealed in plastic bags and kept in a water bath at 70 °C for 3-6 hours. Handsheets were prepared and equilibrated in a constant humidity room before measuring brightness.
-
- Laboratory drum drier.
- "Elrepho 3000," "Technidyne Color Touch 2 (Model ISO)" or another instrument for brightness measurements.
- Hitachi F-4500 fluorescence spectrometer or another instrument for relative fluorescence intensity measurements.
- Micropipette.
- Surface size application kit (pad and size 3-application rod).
- Constant humidity room (23 °C, 50% humidity).
- Water bath /thermostat accommodating a floating plastic box with paper samples
- 100-mL application cuvette for the soaking method.
-
- 1. Prepare 8x8-inch hand sheet according to the standard procedure. The target dry weight is 2.5 g. Pass wet hand sheets through one cycle on the drum dryer.
- 2. Cut the sheets into 4 smaller squares (approximate wt of 0.625 g each).
- 3. Tape one side of the smaller square (test sheet) to a glass pad using Scotch tape of length greater than the side of the sheet.
- 4. The application rod is placed on the scotch tape and a volume of 0.2 ml of the mix is applied on the tape against the rod using a micropipette.
- 5. The agent solution is applied in such away that it is evenly distributed on the tape to cover the entire test sheet.
- 6. Quickly draw the solution from the tape over sheet using the rod so that the reducing agent compound solution is evenly applied on to the entire sheet.
- 7. Drum-dry the test sheet and equilibrate at room temperature.
- 8. Measure brightness and yellowness.
-
- 1. Prepare 8x8-inch hand sheet according to the standard procedure. The target dry weight is 2.5 g. Pass wet hand sheets through one cycle on the drum dryer.
- 2. Cut 1/8th strip of the sheet (0.31g).
- 3. In a 50 ml test tube, prepare solutions of pre-cooked starch (if needed) and reducing agent compound solutions based on the pre-determined pickup rate and target dose.
- 4. Dip the paper strip into the solution for 10 seconds, let it drip for 35 seconds and then pass it through the press.
- 5. Drum-dry the test sheet and equilibrate at room temperature.
- 6. Measure brightness and yellowness.
-
- 1. An 8x8-inch sheet is made and dewatered using the press with two blotters at the bottom and one blotter on top. The consistency of the pressed sheet is around 40%.
- 2. The top blotter and the bottom most blotter are removed from the sheet after the press.
- 3. The sheet along with one bottom blotter are cut into 4 smaller test sheets of equal size (approximate dry weight of the sheet is 0.625 g).
- 4. The test sheet is taped along with the blotter to the glass pad as described in the "dry surface application procedure."
- 5. Solution 1 is applied as described in the dry surface application procedure.
- 6. After application, the test sheet along with the wet blotter is removed from the glass pad, the tape is removed and the blotter is separated from the test sheet. The blotter is discarded.
- 7. The test sheet is then drum dried and equilibrated at room temperature.
-
- 1. An 8x8-inch sheet is made according to the standard procedure.
- 2. The sheet formed on the screen is then padded with 4 blotters.
- 3. The sheet along with blotters is then couched using a heavy metal roller. This process removes excess water from the sheet to increase the consistency of the sheet to around 20%.
- 4. Three top blotters are removed from the sheet.
- 5. The sheet and one blotter are then removed from the screen and cut into 4 smaller pieces as described in the "Wet end Application Procedure".
- 6. The sheet and the blotter are then taped to the glass pad as described in the "Wet end Application Procedure".
- 7. Solution 2 is applied as described in the "Wet end Application Procedure".
- 8. The test sheet is then pressed with 2 blotters on each side.
- 9. After press, all the blotters are removed and the sheet is drum dried.
- The chemicals were added directly to the pulp (thin stock or thick stock) and mixed with the pulp in sealed bags. In a pulp application procedure for OBA enhancement the chemicals were added directly to the bleached kraft pulp at 20% consistency, mixed with the pulp in sealed bags and kept at 45-80 °C for 30 min. The pulp was diluted to 5% consistency, the OBA was added, mixed with the pulp, and the slurry was kept at 50 °C for 20 min. Then the slurry was further diluted and hand sheets prepared according to the standard procedure.
- The trial data were collected at a Southern kraft mill. The table below gives sample data. In several tests, application of the product (Composition A) in a size press, with an OBA in the sizing solution, at 5 lb/t and higher doses consistently provided a 1.5-point brightness increase accompanied by improved color of the paper sheet (reflected in decreasing DE values). Returning to the standard mill conditions (no penetrant composition applied) resulted in a decrease of brightness to the background level. This experiment was reproduced three times.
Table 2 Trial Data: R457 Brightness, E313 Whiteness, DE(ΔE)=Sq.rt.[(L0-L)2+(a0-a)2+(b0-b)2] Time, h. Dose, lb/t Brightness DE WI E313 0 0 94.5 1.99 142.24 0.58 0 94.5 1.61 144.95 1.17 0 94.5 1.83 143.34 1.75 0 94.5 1.93 143.52 2.33 0 94.5 1.52 146.66 2.92 4 95.25 0.71 150 3.5 4 95.25 0.89 148.29 4.08 4 95.5 0.88 148.4 4.67 5 96 0.76 149.46 5.25 5 96 0.72 149.84 5.83 6 96 0.44 152.6 6.42 8 96 0.44 156.01 7 8 96 0.35 154.15 7.58 8 95.75 0.4 154.92 8.17 10 96 0.52 152.24 - Several compositions were tested and gave good results in laboratory simulation of the PM application. The chemicals (compositions) not listed in Table 1 were applied as 40% solutions.
-
Table 3 Mixed Kraft-CTMP 1, headbox, surface application with starch (surface sizing solution) on both sides # Treatment Br 1 Control 94.34 2 0.27% Sodium Metabisulfite 96.17 Table 4 Mixed Kraft-CTMP 2, headbox, surface application with starch (surface sizing solution) on both sides # Treatment Br 1 Control 94.93 2 0.27% Sodium Metabisulfite 95.63 Table 5 Mixed kraft-CTMP 3, headbox # Treatment Br Gain vs. Control Gain vs. OBA 1 Control 85.47 0 2 0.2%OBA 89.78 4.31 0 3 0.2%OBA+0.2%Composition A 91.05 5.58 1.27 4 0.2%OBA+0.054% Sodium Metabisulfite 90.6 5.13 0.82 5 0.054% Sodium Metabisulfite 86.31 0.84 Table 6 Finished (sized) photocopying kraft 1, surface application with starch (surface sizing solution) on one side # Treatment Br 1 Control 80.00 2 0.27% Sodium Metabisulfite 80.50 Table 7 Finished (sized, with OBA) kraft 2, surface application with starch (surface sizing solution) on one side # Treatment Br 1 Control 94.78 2 0.27% Sodium Metabisulfite 95.39 Table 8 Mechanical-kraft 2 # Treatment Br 1 0.2% Sodium metabisulfite 63.81 2 Drum-dried (100°C) 62.28 3 Air-dried (23°C) 64.87 - Tables 3-8 illustrate the effect of a reducing agent sodium bisulfite (metabisulfite) and a brightness enhancing composition on paper brightness: the reducing agent improves brightness (Tables 3-8), partially compensating for the brightness loss in the dryer (Table 8). The chemistry further more improves brightness in presence of an OBA (Table 5).
- Application in a model surface sizing solution with starch
Table 9 TMP1 # Treatment Br Ye 1 0.2% THP 78.66 12.38 2 0.2% FAS 78.75 12.20 3 0.2% TCP 79.20 12.13 4 0.2% FAS 78.00 12.17 5 0.2% THP + 0.01% NaNO2* 79.22 12.00 6 0.2% TCP + 0.01% NaNO2* 79.11 12.12 7 Control 77.51 12.98 * An activator Table 10 TMP1 # Treatment Br Ye 1 Control 78.83 11.95 2 0.2% BTHP 81.06 10.90 Table 11 RMP # Treatment Br Ye 1 Control 76.75 13.57 2 0.2% BTHP 78.59 12.64 3 0.2% BTHP + 0.01% NaNO2* 78.75 12.54 4 0.2% TCP + 0.01% NaNO2* 78.38 12.70 * An activator - Tables 9-11 demonstrate the effect of reducing chemicals other than sodium metabisulfite, such as FAS and phosphorous (III) compounds.
-
Table 12 Kraft hardwood pulp 3, headbox # Treatment Br 1 0% OBA 2 87.56 2 0% OBA 2 + 0.1% Composition C 88.07 3 20% OBA 92.08 4 20% OBA + 0.1% Composition C 92.80 5 40% OBA 93.05 6 40% OBA + 0.1% Composition C 93.60 7 100% OBA 93.43 8 100% OBA + 0.1% Composition C 93.95 Table 13 Mixed kraft-CTMP 3, activation of an optical brightener # Treatment Br Gain vs. Control Synergism 1 Control 85.48 0 N/A 2 0.2% Composition C 86.79 1.35 N/A 3 0.2% OBA 89.7 4.21 N/A 4 0.35% OBA 90.73 5.22 N/A 5 0.1% Composition C 86.34 0.81 N/A 6 0.2% OBA + 0.2% Composition C 91.4 5.82 0.26 7 0.2% OBA + 0.1% Composition C 90.78 5.25 0.23 8 0.35% OBA + 0.2% Composition C 92.55 6.87 0.30 9 0.35% OBA + 0.1% Composition C 92.06 6.54 0.51 Table 14 Activation of an optical brightener: kraft pulp 4, Composition C (0, 0.2%) with OBA (0, 0.2%) Br vs.(0,0) OBA1 C0, OBA0 78.24 0 C0, OBA0.2 79.74 1.5 C0.2, OBA0 80.43 2.19 C0.2, OBA0.2 82.53 4.29 Synergism 0.6 Table 15 Mixed kraft-CTMP 1, headbox, activation of an optical brightener as measured by fluorescence intensities: Sample Fluoresc. Intensity Control 33746 0.2% Composition A 36149 0.35% OBA 106233 0.1% Composition A + 0.35% OBA 111609 0.2% Composition A + 0.35% OBA 116373 0.3% Composition A + 0.35% OBA 119845 Table 16 Kraft headbox containing OBA, activation of an optical brightener as measured by fluorescence intensities: Sample Fluoresc. Intensity Control 87140 0.1% Composition A 106217 0.2% Composition A 108942 0.2% OBA 117513 0.2% Composition A + 0.2% OBA 120837 Table 17 Mixed furnish (25% softwood, 40% hardwood kraft, 35% deinked), activation of an optical brightener as measured by fluorescence intensities: Sample Fluoresc. Intensity Control 57121 0.2% Composition A 57567 0.91% OBA 61339 0.2% Composition A + 0.6% OBA 60783 0.2% Composition A + 0.45% OBA 60868 0.2% Composition A + 0.3% OBA 59924 Table 18 TMP 2 Treatment Br Ye Control 78.43 12.06 0.2% Composition B 81.11 10.70 0.2% (Sodium metabisulfite 3 : DTPA 1) 81.31 10.52 Table 19 TMP 2 # Treatment Br Ye 1 Control 78.83 11.95 2 0.05% FAS + 0.15% Composition B 81.35 10.72 3 0.2% BTHP 81.06 10.90 4 0.1% BTHP + 0.1% Composition B 80.28 11.32 5 0.2% (BTHP 3 : DTMPA 1) 81.40 10.73 6 0.2% Composition B 81.30 10.90 Table 20 Hardwood kraft 2 # Treatment Br Ye 1 Control 87.48 4.21 2 0.2% Composition B 88.38 3.65 3 0.2% (Sodium metabisufite 30: DTPA 5: DTMPA 5) 88.40 3.35 Table 21 Kraft 2, surface sizing application # Treatment Br Ye 1 0.513% Composition A, Drum dried 88.41 3.51 2 Drum dried 87.50 4.01 3 Air dried 88.16 3.56 Table 22 Kraft 2, surface sizing application # Treatment Br 1 0.2% Composition A, Drum dried 88.31 2 Drum dried 87.76 3 Air dried 88.67 Table 23 Mechanical-kraft pulp blend, headbox furnish, wet end application Br 0.1% Sodium metabisulfite + 0.1% (DTMPA 2 : Polyacrylate 1, 33% actives), Drum dried 65.16 Drum-dried 62.28 Air-dried 64.87 Table 24 Kraft 5, treated handsheets, 4 days at 70°C, 100% humidity # Treatment Im Br TA Br TA loss 1 Control 93.75 92.74 1.01 2 0.2% Composition A 94.41 93.57 0.84 3 0.5% Composition A 95.16 94.40 0.76 4 0.2% Composition G 94.23 93.41 0.82 5 0.5% Composition G 94.68 94.04 0.64 Table 25 Kraft 5, treated handsheets, 4 days at 70°C, 100% humidity # Treatment Im Br TA Br TA loss 1 Control 93.42 92.13 1.29 2 0.2% OBA 94.20 92.76 1.44 3 0.2% Composition A + 0.2% OBA 95.05 94.59 0.46 4 0.2% Composition G + 0.2% OBA 94.89 94.39 0.50 5 0.5% Composition G 94.59 94.17 0.42 Table 26 Kraft 2, 10% consistency pulp, 3 h at 70°C # Treatment Br 1 Original pulp (no exposure to heat) 88.05 2 Control (exposure to heat) 87.11 3 0.2% Composition A 87.99 4 0.2% Composition G 87.90 5 0.5% Composition A 87.94 6 0.5% Composition G 88.47 Table 27 Kraft 2, 10% consistency pulp, 6 h at 70°C # Treatment Br 1 Original pulp (no exposure to heat) 88.67 2 Control (exposure to heat) 87.76 3 0.2% Composition A 88.31 4 0.2% Composition G 88.34 5 0.5% Composition A 88.61 6 0.5% Composition G 88.67 - Tables 12-27 illustrate application of compositions where a reducing agent is combined with chelant(s). Different combinations can be compared (all effective). The formulations improve long-term brightness stability of paper toward thermal aging (Tables 24-27). This set of data also demonstrates an OBA activation by the compositions (Tables 12-14, 25). Applying the formulation allows cutting the dose of an optical brightener. Tables 16 and 17 illustrate the effect of the formulation on fluorescence.
- Pulp Application Procedure (80°C) for Subsequent OBA Enhancement
Table 28 Kraft 6 # % Composition A %OBA Br Gain vs. Control 1 0 0 86.78 0.00 2 0 0.5 88.70 1.92 3 0 0.25 88.22 1.44 4 0.5 0 88.05 1.27 5 0.5 0.5 91.04 4.26 6 0.50 0.25 89.38 2.60 7 0.25 0.25 90.55 3.77 Table 29 Kraft 6 # % Composition G %OBA Br Gain vs. Control 1 0 0 86.64 0.00 2 0.5 0.5 91.66 5.02 3 0.5 0.25 90.69 4.05 4 0.25 0.25 89.32 2.68 5 0 0.5 89.00 2.36 6 0.5 0 87.68 1.04 Table 30 Kraft 6, activation of an optical brightener as measured by fluorescence intensities: Sample Fluoresc. Intensity Control 7871 0.5% Composition G 10370 0.5% OBA 128578 0.5% Composition G, then 0.5% OBA 201199 0.25% Composition G, then 0.5% OBA 161354 0.5% Composition G, then 0.25% OBA 157359 0.5% Composition A, then 0.5% OBA 191759 - Tables 28-30 illustrate activation of an OBA via prior application of a composition.
-
Table 31 RMP, couch (wet end) application in water # % Composition A % DTC Br Ye 1 0.257% 0.0025% 79.53 11.65 2 0.257% 0.00125% 79.73 11.93 3 0.184% 0.0025% 80.05 11.63 4 0.184% 0.00125% 79.98 11.51 Air dried 80.15 11.30 Drum dried 78.28 12.60 Table 32 RMP, surface sizing application # % Composition A % DTC Im Br Im. Ye TABr TAYe % Inh. 1 0.513% 0.0025% 79.35 12.16 77.91 12.56 27 2 0.513% 0.0050% 78.78 12.65 77.79 12.7 50 Drum dried 77.9 12.92 75.93 13.82 Table 33 Kraft, surface sizing application # % Composition A % DTC Im Br Im Ye TABr TAYe % Inh. 1 0.513% 0.0025% 87.74 3.98 86.24 4.46 31 2 0.513% 0.0050% 87.17 4.52 86.27 4.54 58 Drum dried 87.64 3.92 85.47 5.05 - The data (Tables 31-33) illustrate brightness recovery and long-term stabilization upon application of the proposed formulations.
Claims (11)
- A method of preparing a bleached pulp material having enhanced brightness and enhanced resistance to thermal yellowing comprising:i) providing bleached pulp material;ii) contacting the bleached pulp material with an effective amount of one or more reducing agents which enhances the brightness and resistance to thermal yellowing of the pulp compared to pulp which is not treated with the reducing agent(s), andiii) contacting the bleached pulp material with one or more optical brighteners selected from the group consisting of azoles, biphenyls, coumarins; furans; naphthalimides; pyrazenes; and salts of such compounds including alkali metal salts, alkaline earth metal salts, transition metal salts, organic salts and ammonium salts; and combinations thereof.
- The method of claim 1 further comprising contacting the bleached pulp material with one or more chelants.
- The method of claim 1, wherein the bleached pulp material is selected from the group consisting of virgin pulp, recycled pulp, kraft pulp, sulfite pulp, mechanical pulp, any combination of such pulps, recycled paper, paper tissue, and any paper or paper products made from such pulps or combinations thereof.
- The method of claim 1 , wherein the reducing agent is selected from the group consisting of sulfites, bisulfites, metabisulfites (pyrosulfites), sulfoxylates, thiosulfates, dithionites (hydrosulfites), polythionates, formamidinesulfinic acid and salts and derivatives thereof, formaldehyde bisulfite adduct and other aldehyde bisulfite adducts, sulfinamides and ethers of sulfinic acid, sulfenamides and ethers of sulfenic acid, sulfamides, phosphines, phosphonium salts, phosphites, and thiophosphites.
- The method of claim 4, wherein the reducing agent is selected from the group consisting of substituted phosphines, sulfites, bisulfites and metabisulfites.
- The method of Claim 5, wherein the reducing agent is sodium bisulfite.
- The method of Claim 2, wherein the chelant is selected from the group consisting of organic phosphonates, phosphates, carboxylic acids, dithiocarbamates, salts of any of the previous members, and any combination thereof.
- The method of Claim 7, wherein the chelant is selected from the group consisting of diethylene-triamine-pentaniethylene phosphonic acid (DTMPA) and salts thereof, diethylenetriaminepentaacetic acid (DTPA) and salts thereof and ethylenediaminetetraacetic acid (EDTA) and salts thereof.
- The method of claim 1 further comprising contacting the bleached pulp material with one or more polycarboxylates.
- The method of claim 9 wherein the polycarboxylate is partially neutralized polyacrylic acid.
- The method of claim 1 wherein the reducing agents and optical brighteners are mixed with a surface sizing solution and applied to the bleached pulp material in a size press.
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Application Number | Priority Date | Filing Date | Title |
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US11/102,318 US20060229393A1 (en) | 2005-04-08 | 2005-04-08 | Compositions and methods for enhancing brightness and brightness stabilization in papermaking |
US71847505P | 2005-09-19 | 2005-09-19 | |
US72184705P | 2005-09-29 | 2005-09-29 | |
US11/387,499 US8246780B2 (en) | 2005-09-19 | 2006-03-23 | Methods for enhancing brightness and resistance to thermal yellowing of bleached kraft pulp and paper |
PCT/US2006/013479 WO2006110751A1 (en) | 2005-04-08 | 2006-04-07 | Improved composition and processes for paper production |
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EP06740857.5A Active EP1866477B1 (en) | 2005-04-08 | 2006-04-07 | Improved composition and processes for paper production |
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EP (1) | EP1866477B1 (en) |
JP (1) | JP5112291B2 (en) |
KR (1) | KR101310192B1 (en) |
AR (1) | AR056309A1 (en) |
AU (1) | AU2006235427B2 (en) |
BR (1) | BRPI0608006B1 (en) |
CA (1) | CA2601507C (en) |
MX (1) | MX2007012385A (en) |
MY (1) | MY177088A (en) |
NO (1) | NO341227B1 (en) |
NZ (1) | NZ562852A (en) |
TW (1) | TWI421390B (en) |
WO (1) | WO2006110751A1 (en) |
Families Citing this family (18)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7638016B2 (en) * | 2005-02-19 | 2009-12-29 | International Paper Company | Method for treating kraft pulp with optical brighteners after chlorine bleaching to increase brightness |
US7914646B2 (en) | 2006-07-21 | 2011-03-29 | Nalco Company | Compositions and processes for paper production |
US8758886B2 (en) | 2005-10-14 | 2014-06-24 | International Paper Company | Recording sheet with improved image dry time |
US7967948B2 (en) * | 2006-06-02 | 2011-06-28 | International Paper Company | Process for non-chlorine oxidative bleaching of mechanical pulp in the presence of optical brightening agents |
DE102007007654A1 (en) * | 2007-02-13 | 2008-08-14 | Voith Patent Gmbh | FAS bleach |
ES2390619T3 (en) | 2008-03-31 | 2012-11-14 | International Paper Company | Print sheet with improved print quality at low additive levels |
CN103088699B (en) | 2008-06-20 | 2015-04-22 | 国际纸业公司 | Composition And Recording Sheet With Improved Optical Properties |
US9932709B2 (en) * | 2013-03-15 | 2018-04-03 | Ecolab Usa Inc. | Processes and compositions for brightness improvement in paper production |
US20100224333A1 (en) * | 2009-03-09 | 2010-09-09 | Prasad Duggirala | Method and chemical composition to improve efficiency of mechanical pulp |
US8652593B2 (en) * | 2009-12-17 | 2014-02-18 | International Paper Company | Printable substrates with improved brightness from OBAs in presence of multivalent metal salts |
US8574690B2 (en) | 2009-12-17 | 2013-11-05 | International Paper Company | Printable substrates with improved dry time and acceptable print density by using monovalent salts |
US8608908B2 (en) | 2010-04-02 | 2013-12-17 | International Paper Company | Method and system using low fatty acid starches in paper sizing composition to inhibit deposition of multivalent fatty acid salts |
US8440053B2 (en) | 2010-04-02 | 2013-05-14 | International Paper Company | Method and system using surfactants in paper sizing composition to inhibit deposition of multivalent fatty acid salts |
WO2011139481A1 (en) | 2010-05-04 | 2011-11-10 | International Paper Company | Coated printed substrates resistant to acidic highlighters and printing solutions |
US8795796B2 (en) | 2010-07-23 | 2014-08-05 | International Paper Company | Coated printable substrates providing higher print quality and resolution at lower ink usage |
US8697203B2 (en) | 2010-11-16 | 2014-04-15 | International Paper Company | Paper sizing composition with salt of calcium (II) and organic acid, products made thereby, method of using, and method of making |
EP3879029A1 (en) * | 2015-05-15 | 2021-09-15 | Nippon Paper Industries Co., Ltd. | Anion-modified cellulose nanofiber dispersion liquid and composition |
JP7378198B2 (en) * | 2017-05-15 | 2023-11-13 | 大王製紙株式会社 | Cellulose fine fiber and its manufacturing method |
Family Cites Families (23)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AU412980B2 (en) * | 1966-10-04 | 1971-05-05 | Commonwealth Scientific And Industrial Research Organization | Processes for whitening and/or retarting sunlight yellowing of protein fibres |
US3619355A (en) * | 1967-09-07 | 1971-11-09 | Georgia Pacific Corp | Method for decreasing aging of paper with sulfites and/or bisulfites and product |
US4383889A (en) * | 1981-09-08 | 1983-05-17 | Nalco Chemical Company | Pulp refining process and additive therefor |
CA1249402A (en) * | 1984-12-21 | 1989-01-31 | Pulp And Paper Research Institute Of Canada | Multistage brightening of high yield and ultra high- yield wood pulps |
SE456168C (en) * | 1987-02-27 | 1991-06-06 | Mo Och Domsjoe Ab | PROCEDURE PROVIDES LIGHTNESS STABILIZATION OF BLACK LIGNIN-CONTENT CELLULOSAMASSA |
JPH01239199A (en) * | 1988-03-18 | 1989-09-25 | Kammerer Gmbh | Production of yellowing stable paper web and yellowing stable support material |
SE468054B (en) * | 1990-12-03 | 1992-10-26 | Mo Och Domsjoe Ab | PAPER AND PROCEDURES FOR PREPARING PAPER |
GB2277749B (en) * | 1993-05-08 | 1996-12-04 | Ciba Geigy Ag | Fluorescent whitening of paper |
JPH07145583A (en) * | 1993-11-22 | 1995-06-06 | Koei Chem Co Ltd | Deinking and bleaching of waste paper |
DE4403480A1 (en) * | 1994-02-04 | 1995-08-10 | Basf Ag | Binder mixtures for paper coating slips |
JP3457435B2 (en) * | 1995-08-04 | 2003-10-20 | 特種製紙株式会社 | Manufacturing method of fluorescent white paper |
EP0899373A1 (en) * | 1997-08-28 | 1999-03-03 | Ciba SC Holding AG | Method of whitening lignin-containing pulp during manufacture |
EP0905317B1 (en) * | 1997-09-16 | 2009-12-23 | Basf Se | A method for optically brightening paper |
NZ331438A (en) * | 1997-09-16 | 2000-01-28 | Ciba Sc Holding Ag | A method of increasing the whiteness of paper by using a formulation containing a swellale layered silicate and an optical brightener 4,4-bis-(triazinylamino)-stilbene-2,2-disulphonic acid |
AU754737B2 (en) * | 1998-10-22 | 2002-11-21 | Ciba Specialty Chemicals Holding Inc. | Inhibition of pulp and paper yellowing using hydroxylamines and other coadditives |
US20020088574A1 (en) * | 1998-10-22 | 2002-07-11 | Raymond Seltzer | Inhibition of pulp and paper yellowing using hydroxylamines and other coadditives |
CA2285823C (en) * | 1998-10-28 | 2007-07-10 | Pulp And Paper Research Institute Of Canada | A method for reducing alkaline darkening of mechanical pulp containing a calcium carbonate filler |
US6428653B1 (en) * | 2000-12-04 | 2002-08-06 | West Fraser Timber Co. Ltd. | Method of bleaching with formamidine sulfinic acid using a reducing agent to eliminate residual peroxide |
US6702921B2 (en) * | 2001-05-01 | 2004-03-09 | Ondeo Nalco Company | Methods to enhance pulp bleaching and delignification using an organic sulfide chelating agent |
US6743332B2 (en) * | 2001-05-16 | 2004-06-01 | Weyerhaeuser Company | High temperature peroxide bleaching of mechanical pulps |
DE10138631A1 (en) * | 2001-08-13 | 2003-02-27 | Basf Ag | Process for the production of coated paper with high whiteness |
WO2004042139A1 (en) * | 2002-11-07 | 2004-05-21 | Nippon Paper Industries Co., Ltd. | Method for improving the discoloration resistance of pulp and pulp improved in discoloration resistance |
US7351764B2 (en) * | 2004-03-31 | 2008-04-01 | Nalco Company | Methods to enhance brightness of pulp and optimize use of bleaching chemicals |
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- 2006-04-07 JP JP2008505649A patent/JP5112291B2/en active Active
- 2006-04-07 AU AU2006235427A patent/AU2006235427B2/en active Active
- 2006-04-07 EP EP06740857.5A patent/EP1866477B1/en active Active
- 2006-04-07 KR KR1020077025735A patent/KR101310192B1/en active IP Right Grant
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- 2006-04-07 WO PCT/US2006/013479 patent/WO2006110751A1/en active Application Filing
- 2006-04-07 TW TW095112411A patent/TWI421390B/en active
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NO341227B1 (en) | 2017-09-18 |
NZ562852A (en) | 2010-12-24 |
NO20074836L (en) | 2007-09-21 |
JP2008536020A (en) | 2008-09-04 |
AU2006235427B2 (en) | 2011-02-03 |
KR20080006582A (en) | 2008-01-16 |
CA2601507C (en) | 2013-09-03 |
AU2006235427A1 (en) | 2006-10-19 |
JP5112291B2 (en) | 2013-01-09 |
TW200700612A (en) | 2007-01-01 |
MX2007012385A (en) | 2008-03-11 |
EP1866477A1 (en) | 2007-12-19 |
AR056309A1 (en) | 2007-10-03 |
WO2006110751A1 (en) | 2006-10-19 |
EP1866477A4 (en) | 2010-09-01 |
CA2601507A1 (en) | 2006-10-19 |
BRPI0608006B1 (en) | 2017-05-02 |
BRPI0608006A2 (en) | 2009-11-03 |
KR101310192B1 (en) | 2013-09-25 |
TWI421390B (en) | 2014-01-01 |
MY177088A (en) | 2020-09-04 |
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