WO2002025007A2 - Matieres lignocellulosiques stables a la lumiere et leur production - Google Patents

Matieres lignocellulosiques stables a la lumiere et leur production Download PDF

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Publication number
WO2002025007A2
WO2002025007A2 PCT/CA2001/001295 CA0101295W WO0225007A2 WO 2002025007 A2 WO2002025007 A2 WO 2002025007A2 CA 0101295 W CA0101295 W CA 0101295W WO 0225007 A2 WO0225007 A2 WO 0225007A2
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pulp
amino
pulps
btmp
tempo
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PCT/CA2001/001295
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English (en)
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WO2002025007A3 (fr
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Thomas Q. Hu
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Pulp And Paper Research Institute Of Canada
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Priority to AU2001291551A priority Critical patent/AU2001291551A1/en
Priority to CA002421397A priority patent/CA2421397A1/fr
Publication of WO2002025007A2 publication Critical patent/WO2002025007A2/fr
Publication of WO2002025007A3 publication Critical patent/WO2002025007A3/fr

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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
    • D21C9/1036—Use of compounds accelerating or improving the efficiency of the processes
    • 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

  • the current invention relates to the field of wood, pulp and paper production. More specifically, it relates to the production of light-stable hgnocellulosic materials, in particular, the production of mechanical wood pulps and papers with much improved light stability, as well as to the resulting pulps and papers having improved light stability.
  • the primary components of wood are the fibrous, hydrophilic carbohydrates (cellulose and hemicelluloses) and the three-dimensional, hydrophobic lignin.
  • wood either in the form of whole logs, wood chips or sawmill residues, must first be reduced to pulps (discrete fibres) by a chemical or mechanical pulping process.
  • pulps discrete fibres
  • pulps are produced in a yield of 45-55% through the dissolution of lignin by the pulping chemicals.
  • chemical pulps is the so-called kraft pulp produced from the kraft pulping process where sodium hydroxide and sodium sulf ⁇ de are used as the pulping chemicals.
  • thermomechanical pulp TMP
  • CTMP chemithermomechanical pulp
  • papers are produced from chemical wood pulps or mechanical wood pulps, or a combination of both, together with various papermakmg additives.
  • lignin-containing mechanical wood pulps have a light, yellow-brown colour. Bleaching of these pulps to a whiter colour is necessary if they are to be used alone or in combination with bleached chemical pulps to make high-quality papers.
  • the whiteness of pulps and papers is commonly estimated by ISO brightness determination which measures the directional reflectance of light at 457 nm of the papers [TAPPI Test Methods, T452 om-92, Tappi Press: Atlanta, 1996].
  • Unbleached, lignin-containing mechanical wood pulps have ISO brightness values between 45-65%, depending on the wood species and the pulping conditions.
  • alkaline hydrogen peroxide in the presence of peroxide stabilizers such as sodium silicate and magnesium sulfate, is capable of bleaching mechanical wood pulps such as spruce TMP from an initial brightness of 55-60% to 70- 80%.
  • Alkaline hydrogen peroxide bleaching of mechanical wood pulps can be carried out in a single-stage or multistage in one or more than one refiner, bleach tower, storage vessel, dryer or mixer.
  • the bleaching chemicals can also be impregnated into the wood chips in one or more than one impregnator and the bleaching achieved during impregnation before refining [Bohn, CPPA 1990 Annual Meeting Preprints, B109 - B114, Montreal, Quebec, 1990].
  • High-yield, lignin-containing mechanical wood pulps, unbleached or bleached, have properties such as high opacity (low show-through) that are desirable for the production of printing and writing papers.
  • papers produced from mechanical pulps yellow lose their brightness) rapidly when exposed to light. Such a light-induced yellowing has limited the wider use of mechanical wood pulps in high-quality papers such as printing and writing papers.
  • the light-induced yellowing (brightness reversion) of lignin- containing mechanical wood pulps is known to be due to the l oxidation of lignin.
  • many methods have been reported for the improvement of the light/brightness stability of mechanical wood pulps or papers. These methods involve either a chemical treatment on pulps aimed at the modification of the yellowing-causing lignin functional groups or a surface treatment on papers made from mechanical pulps with yellowing inhibitors such as an UV absorber [Heitner, in: Photochemistry of Hgnocellulosic Materials, ed. Heitner and Scaiano, p.192 - 204, ACS Symposium Series 531, ACS 1993].
  • European patent, No. 0,280,332 published on August 31, 1988 describes a pulp chemical treatment method that improves the light/brightness stability of peroxide-bleached mechanical wood pulps.
  • This pulp treatment method involves the reduction of lignin V-carbonyl and (-carbonyl groups with sodium borohydride, the blocking of the phenolic hydroxyl groups with gaseous ethylene or propylene oxide and, in some cases, the application of a fluorescent chemical.
  • the treatment is rather complicated with washing, dewatering and temperature adjustment between the borohydride and the gaseous ethylene or propylene oxide treatment.
  • Several paper surface treatment methods that improve the light/brightness stability of papers made from mechanical pulps have been described. One example of these methods can be found in United States patent, No.
  • the method comprises the steps of forming mechanical pulps into a paper sheet and treating the paper sheet with a formyl compound yellowing inhibitor by spraying the inhibitor in a solution or solid form onto the paper sheet.
  • Hindered amine light stabilizers have been widely used for the light stabilization of synthetic polymers such as polyolefins [Minagawa, Polymer Degradation and Stability 25_ ⁇ 121-141, 1989].
  • the light-induced yellowing (brightness reversion) of mechanical wood pulps is known to be due to the oxidation of lignin phenoxy radicals generated from lignin phenols and V-carbonyl or V-hydroxyl-3-0-4 ethers to the yellow o-quinones [Leary, J. Pulp Paper Sci. 20(6): J154-160, 1994].
  • Chemical modifications of the yellowing-causing lignin functional groups such as the reduction of lignin V-carbonyl groups by borohydride and the blocking of the lignin phenolic hydroxyl groups by gaseous ethylene oxide can be performed on pulps to give mechanical pulps with improved brightness stability.
  • UV absorbers possessing an epoxide or isocyanate functional group have been grafted to the surface of wood in organic media to improve the light stability of the wood [Williams, J. Appl, Polym. Sci. 28: 2093-2103, 1983; Grelier, et al, Holzforschung 51: 511-518, 1997].
  • This invention seeks to provide a method for the production of a light-stable hgnocellulosic material.
  • the invention also seeks to provide novel hgnocellulosic material obtainable by the method of the invention.
  • the invention further seeks to provide a paper containing the novel hgnocellulosic material of the invention.
  • a method for the production of light-stable, hgnocellulosic materials such as mechanical wood pulps comprising reacting the materials with a water- soluble, yellowing inhibitor possessing a primary or secondary amino group of the formula A, B, C or D wherein Y is oxyl (O ) or hydroxyl (OH) in an aqueous medium, or with a water-soluble hindered amine light stabilizer of the formula A or B wherein Y is hydrogen (H) in an alkaline peroxide bleaching medium or in an aqueous medium with a subsequent bleaching of the materials in an alkaline peroxide bleaching medium:
  • W is hydrogen or an alkyl group (CH 2 ) n H that is unsubstituted or substituted by 1 to 2n+l number of a hydroxyl, ether, thio, thioether, benzyl, amino, ester, amide, carboxyl and/or carboxylate [(COO ' ⁇ M 14' ] group, and/or radicals derived from an organic ultraviolet absorber
  • R 2 , R 3 , R and R 5 are independently alkyl group (CH 2 ) n H that are unsubstituted or substituted by 1 to 2n+l number of a hydroxyl, ether, thio, thioether, amino, ester, amide, carboxyl and/or carboxylate [(COO ' ⁇ M 14" ] group, and/or radicals derived from an organic ultraviolet absorber
  • X is an inorganic or organic anion
  • n is 1 to 14, preferably 1 to 6, and more preferably 1 to 4
  • k is
  • the present invention produces light-stable lignocellulosic materials such as various wood products and mechanical wood pulps by developing water-soluble, fibre-reactive yellowing inhibitors and attaching them to the lignocellulosic materials, for example wood pulps, in aqueous media.
  • the resulting light-stable mechanical wood pulps can then be used to make papers composed mainly of mechanical wood pulps, including high quality printing and writing papers as well as newsprint and telephone directory, with improved brightness stability. These pulps can also be used to replace a part of the chemical wood pulps in high-quality papers such as printing and writing papers.
  • lignocellulosic materials such as mechanical wood pulps with much improved light/brightness stability can be produced by reaction of the material with a water-soluble, fibre-reactive yellowing inhibitor possessing a primary or secondary amino (-NH 2 or - NHR) functional group in an aqueous medium, or with a water-soluble, hindered amine light stabilizer (HALS) possessing a primary or secondary amino (-NH 2 or -NHR) functional group in an alkaline peroxide bleaching medium, or in an aqueous medium with a subsequent bleaching of the material in an alkaline peroxide bleaching medium.
  • a water-soluble, fibre-reactive yellowing inhibitor possessing a primary or secondary amino (-NH 2 or - NHR) functional group in an aqueous medium
  • HALS hindered amine light stabilizer
  • Alkaline peroxide bleaching medium in the present specification contemplates the medium used for a single-stage or multi-stage alkaline hydrogen peroxide bleaching of wood pulps in one or more than one refiner, bleach tower, pulp mixer, and/or any other vessel or the medium used for a single-stage or multi-stage alkaline hydrogen peroxide impregnation of wood chips in one or more than one impregnator.
  • An aqueous medium in the present specification includes the said alkaline peroxide bleaching medium.
  • a method for the production of a light-stable lignocellulosic material such as mechanical wood pulp comprising reacting the material with a water-soluble yellowing inhibitor possessing a primary or secondary amino group in an aqueous medium, or with a water-soluble hindered amine light stabilizer possessing a primary or secondary amino group in an alkaline peroxide bleaching medium or in an aqueous medium with a subsequent bleaching of the material in an alkaline peroxide bleaching medium.
  • a light-stable, lignin-containing mechanical wood pulp comprising a lignin-containing mechanical wood pulp having a water-soluble yellowing inhibitor possessing a primary or secondary amino group, said inhibitor being linked to said pulp via said amino group.
  • the pulp component comprises a pulp of the invention, as described hereinbefore, as the sole pulp component or in conjunction with chemical wood pulp.
  • Paper sheet in the present specification contemplates paper or paperboard.
  • water-soluble, fibre- reactive yellowing inhibitors and hindered amine light stabilizers are provided that are capable of forming covalent bonds to and thus being retained by lignocellulosic materials such as mechanical wood pulp fibres in aqueous media.
  • lignocellulosic materials such as mechanical wood pulp fibres in aqueous media.
  • no yellowing inhibitors possessing an epoxide, isocyanate, or any other functional groups have been attached to wood pulp fibres, either in organic or in aqueous media.
  • hindered amine light stabilizer has been found to be detrimental to the brightness stability of papers made from mechanical pulps. No hindered amine light stabilizer has previously been used in any pulping or bleaching process to make pulps or papers.
  • lignocellulosic materials with improved light/brightness stability can be produced by reacting the materials with a hindered amine light stabilizer possessing a primary or secondary amino (-NH 2 or -NHR) group in an alkaline peroxide bleaching medium, or in an aqueous medium with a subsequent bleaching of the materials in an alkaline peroxide bleaching medium.
  • a hindered amine light stabilizer possessing a primary or secondary amino (-NH 2 or -NHR) group in an alkaline peroxide bleaching medium, or in an aqueous medium with a subsequent bleaching of the materials in an alkaline peroxide bleaching medium.
  • the present invention is based on such surprising discoveries.
  • the importance of the amino group in providing the fibre-reactivity to the yellowing inhibitors is explicitly demonstrated in examples 1 and 2 of the present invention where 4-amino-TEMPO but not 4-hydroxy-TEMPO is shown to be reactive towards mechanical wood pulp fibres.
  • Pulps reacted with 4-amino-TEMPO in aqueous media and then washed repeatedly with water retain a significant amount of the radical scavenger (as indicated by the increased nitrogen content of the pulps) and show much higher brightness stability than the control samples.
  • pulps treated with 4-hydroxy-TEMPO do not retain any of the reagent and do not show any improved brightness stability.
  • example 25 of the present invention where addition of 4-amino-2,2,6,6-tetramethylpiperidine, but not 4-oxo-2,2,6,6-tetramethylpiperidine, to an alkaline peroxide bleaching of the pulp is shown to provide the pulp with improved brightness stability.
  • HALS hindered amine light stabilizers
  • lignocellulosic materials such as mechanical wood pulps with much improved light/brightness stability
  • a water-soluble, yellowing inhibitor possessing a primary or secondary amino (-NH 2 or - NHR) functional group of the formula A, B, C or D wherein Y is oxyl (O ) or hydroxyl (OH) in an aqueous medium, or with a water-soluble hindered amine light stabilizer (HALS) of formula A or B wherein Y is hydrogen (H) in an alkaline peroxide bleaching medium or in an aqueous medium with a subsequent bleaching of the materials in an alkaline peroxide bleaching medium:
  • HALS water-soluble hindered amine light stabilizer
  • ⁇ is hydrogen or an alkyl group (CH 2 ) n H that is unsubstituted or substituted by 1 to 2n+l number of a hydroxyl, ether, thio, thioether, benzyl, amino, ester, amide, carboxyl and/or carboxylate [(COO ⁇ M 14" ] group, and/or radicals derived from an organic ultraviolet absorber such as 2,4-dihydroxybenzophenone;
  • R 2 , R 3 , R 4 and R 5 are independently alkyl groups (CH 2 ) n H unsubstituted or substituted by 1 to 2n+l number of a hydroxyl, ether, thio, thioether, benzyl, amino, ester, amide, carboxyl and/or carboxylate [(COO ' M ⁇ ] group, and/or radicals derived from an organic ultraviolet absorber, such as 2,4-dihydroxybenzophenone;
  • X is an inorganic or organic anion
  • a "radical derived from an organic ultraviolet absorber” means a radical of the absorber which has the ultraviolet absorbing characteristic of the absorber and thus introduces such characteristic into the inhibitor or stabilizer of formulae A to D.
  • water-soluble, fibre-reactive yellowing inhibitors is the commercially available radical scavenger, 4-amino-2,2,6,6- tetramethylpiperidine-N-oxyl (4-amino-TEMPO) (available from Aldrich).
  • the reactions of the inhibitors with the lignocellulosic materials can be suitably carried out at a temperature of 20 - 120 °C and a consistency of 1.5 to 40% in an alkaline peroxide bleaching medium or an aqueous medium in a pH range of 3.5-12.5.
  • the inhibitor charge can suitably range from 0.01 to 2.0% by weight based on oven-dried (OD) lignocellulosic material, e.g.
  • pulp weight preferably at least 0.05%, more preferably at least 0.1% and most preferably from 0.2 to 1.0%, by weight.
  • the reaction may conveniently be carried out in a time of 5 minutes to several days (e.g. 3 to 5 days).
  • Y is oxyl such as 4- amino-TEMPO
  • Y is oxyl such as 4- amino-TEMPO
  • a BTMP pulp reacted with 1% (OD pulp) of 4-amino-TEMPO has an ISO brightness only 1.9 points lower than the control pulp compared to a drop of 7.1 ISO brightness points when a sheet is coated with 1% (OD pulp) of 4-amino-TEMPO.
  • the brightness stability of the pulp reacted with 4-amino-TEMPO is similar to that of the sheet coated with 4-amino-TEMPO.
  • the small drop in initial brightness when pulps are reacted with 3 0.5% (OD pulp) of 4-amino-TEMPO can also be avoided by carrying out the reaction at pH ⁇ 6.5 by addition to the reaction media of, or by treating the resulting pulps with a small amount of an organic or inorganic acid such as citric acid, hydrochloric acid or sulfurous acid in the form of aqueous sulfur dioxide (S0 2 ).
  • an organic or inorganic acid such as citric acid, hydrochloric acid or sulfurous acid in the form of aqueous sulfur dioxide (S0 2 ).
  • the reaction with the inhibitor may be carried out in the presence or absence of air or oxygen.
  • HALS water-soluble, fibre-reactive, hindered amine light stabilizers
  • Y is hydrogen
  • the reactions of HALS with lignocellulosic materials can be carried out similarly to the reactions of the yellowing inhibitors.
  • the alkaline peroxide bleaching media used for the reactions of the said fibre-reactive yellowing inhibitors or HALS with and the bleaching of, mechanical wood pulps can be carried out at a temperature of 20 - 120 °C, a consistency of 1.5 - 50% and a bleaching time of five minutes - several days.
  • the alkaline peroxide impregnation of the wood chips in the presence of the said yellowing inhibitors or hindered amine light stabilizers can be carried out at a temperature of 40 - 90 °C, a solid content of 30 - 60%, by weight, and an impregnation time of five minutes to two hours.
  • the charge of bleaching or impregnation chemicals, hydrogen peroxide, sodium hydroxide (or hydroxide or oxide of other metals), sodium silicate and magnesium sulfate can be varied depending on the target brightness, the economics, the mill configurations and other process conditions.
  • the charge of a fibre-reactive yellowing inhibitor or hindered amine light stabilizer can suitably range from 0.05 to 2.0% by weight based on oven-dried (OD) pulp weight, preferably from 0.1 to 1.0%, by weight.
  • reaction with the stabilizer, and the bleaching can be carried out in the presence or absence of air or oxygen.
  • mechanical wood pulps with nearly complete brightness stability can be produced by reaction with the said yellowing inhibitors or HALS, and then by coating of the paper made from the resulting pulps with an organic or inorganic ultraviolet absorber, if Ri, R 2 , R 3 , and R 5 in the said yellowing inhibitors or HALS do not contain an organic ultraviolet absorber.
  • the modified pulp of the invention may be the sole pulp component of a paper sheet formed from the pulp, or it may be employed in conjunction with chemical wood pulp.
  • the paper may have a pulp component comprising 1 to 100% by weight of the modified pulp of the invention and 0 to 99%, by weight of a chemical wood pulp, to a total of 100%.
  • FIG. 1 shows the post colour (PC) numbers versus ambient office fluorescent light exposure times of a spruce bleached thermomechanical pulp (BTMP) and the BTMP pulps reacted, respectively, with 1.0% and 0.2% (based on pulp) of a water-soluble yellowing inhibitor, 4-amino- 2,2,6,6-tetramethylpiperidine-l-oxyl (4-amino-TEMPO) to produce modified pulps of much improved light/brightness stability in accordance with the invention;
  • PC post colour
  • FIG. 2 shows the ISO brightness values versus light exposure times of the same pulps
  • FIG. 3 shows the ISO brightness values versus ambient office light exposure times of a spruce BTMP and a spruce BTMP pulp bleached in the presence of 1.0%, by w , (based on pulp) of a hindered amine light stabilizer, 4-amino-2,2,6,6-tetramethylpiperidine to produce a bleached pulp of improved brightness/light stability in accordance with the invention; and
  • FIG. 4 shows the PC numbers versus light exposure times of the same pulps.
  • a known amount of a mechanical wood pulp is mixed with deionized water to give a pulp consistency of 1.5%.
  • Consistency is the weight percentage of pulp in a pulp and water mixture.
  • the pulp slurry is purged with N 2 and kept at room temperature ( ⁇ 20 °C) or heated to a desired temperature.
  • a said water-soluble, yellowing inhibitor or HALS (0.01 - 2.0%> on pulp) is added.
  • the pH of the pulp slurry is adjusted to a desired value (3.5 - 12.5) by addition of a small amount of NaOH or 6% S0 2 solution.
  • the pulp slurry is stirred for 3 hours unless otherwise specified.
  • the pH of the pulp slurry is then adjusted to near neutral (pH 6.5 - 7.0) when necessary.
  • the pulp slurry is diluted, unless otherwise specified, with deionized water to 0.5 to 1.0% consistency, filtered and washed with deionized water. Unless otherwise specified, the filtered pulp is diluted with deionized water, stirred and filtered two more times.
  • the pulp slurry is then diluted with deionized water to 0.5 to 1.0% consistency, filtered and washed with deionized water. Unless otherwise specified, the filtered pulp is diluted with deionized water, stirred and filtered two more times.
  • the mechanical wood pulp Prior to bleaching, the mechanical wood pulp is treated/chelated with a chelating agent such as diethylenetriaminopentaacetic acid, pentasodium salt (DTPA-Na 5 ) (0.2-0.6%) at 50 °C, pH 5-6 and 2% consistency for 30 minutes to remove metal ions [Ali et al. J. Pulp Paper Sci., 12(6): J166- 172, 1986].
  • a chelating agent such as diethylenetriaminopentaacetic acid, pentasodium salt (DTPA-Na 5 ) (0.2-0.6%) at 50 °C, pH 5-6 and 2% consistency for 30 minutes to remove metal ions [Ali et al. J. Pulp Paper Sci., 12(6): J166- 172, 1986].
  • the chelating agent is added directly to the bleaching of the pulps, thus eliminating the pretreatment stage.
  • Chelated or unchelated mechanical pulp (normally 12 g OD) is mixed in a Hobart mixer with a known amount of magnesium sulfate, sodium silicate, sodium hydroxide, hydrogen peroxide, a chelating agent (for unchelated pulp), a fibre-reactive yellowing inhibitor or HALS (0.01 - 2.0% on pulp) and deionized water to give a pulp of desired consistency (5.0 - 40%).
  • a temperature ⁇ 100 °C the pulp is then transferred to a polyethylene bag, sealed, and immersed in a hot water bath set at a known temperature (> 20 °C, ⁇ 100 °C) for a known bleaching time with occasional manual mixing.
  • the pulp For bleaching at 3 100 °C, the pulp is placed in a pyrex beaker, covered with a watch glass and heated in an autoclave oven set at a known temperature (100 -120 °C) for a known bleaching time. At the end of bleaching, the pulp, either in the bag or in the beaker is cooled in a cold water bath to room temperature ( ⁇ 20 °C). The pulp is diluted with deionized water, unless otherwise specified, to a consistency of 0.25 to 1.0%. The pH of the pulp slurry is adjusted to 6.5 by addition of 6% aqueous sulfur dioxide solution or IN sulfuric acid. The pulp is filtered with recycling of the filtrate to recover fines, and washed thoroughly with deionized water, unless otherwise specified.
  • Ambient office light exposures of selected handsheets are carried out by placing the handsheet samples on a laboratory bench under normal cool-white fluorescent office lights at a normal distance of about six feet with the lights being on 24 hours a day. Unless otherwise specified, the light intensity for such ambient fluorescent office light is measured to be 145 V 2 foot-candle. Measurements of the % ISO brightness of the samples on a Technibrite Micro TB-1C instrument according to TAPPI Test Methods, T 452 om-92, are done at different time intervals and converted to post color number (PC number).
  • PC number post color number
  • the total nitrogen contents of the 4-hydroxy-TEMPO treated and 4-amino-TEMPO treated BTMP pulps are 0.04% and 0.16% (on pulp), respectively, which correspond to an attachment of 0.0% (on pulp) of 4-hydroxy-TEMPO and 0.67% (on pulp) of 4-amino-TEMPO to the BTMP pulps.
  • BTMP pulps as the ones used in example 1 were treated with the H 2 0-soluble 4-hydroxy-TEMPO (2.0% OD pulp) and 4-amino- TEMPO (2.0% OD pulp), respectively, at room temperature ( ⁇ 20 °C) and pH 6.5 - 7.0 according to the general procedure A disclosed.
  • Table 2 lists the PC numbers of the original BTMP, the BTMP pulps treated with 4- hydroxy-TEMPO and 4-amino-TEMPO, respectively, versus the accelerated light exposure times.
  • treatment with 4-amino-TEMPO greatly improves the brightness stability of the BTMP pulp while treatment with 4-hydroxy-TEMPO does not improve the brightness stability of the pulp as seen by inspection of the PC numbers.
  • the total nitrogen contents of the BTMP pulps treated with 4-hydroxy-TEMPO and 4-amino-TEMPO are 0.05% and 0.19% (on pulp), respectively, which correspond to an attachment of 0.0% (on pulp) of 4-hydroxy-TEMPO and 0.85% (on pulp) of 4-amino-TEMPO to the BTMP pulps .
  • BTMP pulps as the ones used in example 1 were treated with the H 2 0-soluble 4-amino-TEMPO at a charge of 2.0% and 1.0% (OD pulp), respectively, at room temperature ( ⁇ 20 °C) and pH 6.5 - 7.0 according to the general procedure A disclosed.
  • Table 3 lists the PC numbers of the original BTMP and the two 4-amino-TEMPO treated BTMP pulps versus the accelerated light exposure times.
  • Treatment with 4-amino- TEMPO at a charge of 1.0% (OD pulp) is nearly as effective as treatment with 4-amino-TEMPO at a charge of 2.0% (OD pulp) in improving the brightness stability of the pulps.
  • the total nitrogen contents of the BTMP pulps treated with 2.0% and 1.0% of 4-amino-TEMPO are 0.19% and 0.15% (on pulp), respectively, which correspond to an attachment of 0.85% and 0.61%) (on pulp) of 4-ammo-TEMPO to the BTMP pulps.
  • a spruce BTMP pulp (ISO brightness 76.2%) was reacted with 1.0% (OD pulp) of 4-amino-TEMPO at room temperature and pH 6.5 - 7.0 according to the general procedure A disclosed. It was also used to prepare a handsheet and then coated with 1% (OD pulp) of 4-amino-TEMPO.
  • Table 4 shows the PC numbers as well as the ISO brightness values of the original BTMP handsheet, the BTMP handsheet coated with 4-amino- TEMPO and the handsheet of the BTMP reacted with 4-amino-TEMPO versus the accelerated light exposure times, respectively.
  • EXAMPLE 5 The same BTMP pulp as the ones used in example 1 was treated with the H 2 0-soluble 4-amino-TEMPO at a charge of 1.0% (OD pulp) at room temperature ( ⁇ 20 °C) and pH 6.5 - 7.0 according to the general procedure A disclosed. The treated pulp was divided into two equiyalent portions. One portion of the pulp was further treated with ascorbic acid (1%) OD. pulp) at room temperature ( ⁇ 20 °C) for one hour at 1.5% consistency.
  • Table 5 lists the PC numbers and the ISO brightness values of the original BTMP, the 4-amino-TEMPO treated BTMP pulp, and the 4- amino-TEMPO and ascorbic acid treated BTMP pulp versus the accelerated light exposure times.
  • Sequential treatment with 4-amino-TEMPO and ascorbic acid not only gives a pulp with much improved brightness stability but also provides a pulp with initial brightness similar to the control pulp.
  • the total nitrogen contents of both the 4-amino-TEMPO treated BTMP and the 4-amino-TEMPO, ascorbic acid treated BTMP are 0.15% (on pulp), which correspond to an attachment of 0.61% (on pulp) of 4-amino-TEMPO to both the BTMP pulps.
  • BTMP Spruce peroxide-bleached TMP
  • BTMP Spruce peroxide-bleached TMP
  • Table 6 shows the PC numbers as well as the ISO brightness of the original BTMP and the two 4-amino-TEMPO treated BTMP pulps versus the accelerated light exposure times.
  • Treatment of the bleached TMP pulps with 4-amino-TEMPO at pH 5.5-6.0 is also effective in greatly improving the brightness stability of the pulps. It is also effective in improving the initial brightness of the BTMP pulp treated with 4-amino- TEMPO.
  • BTMP pulps as the one used in example 5 were treated with 1.0% (OD pulp) of 4-amino-TEMPO at 60 °C and pH 6.5-7.0, and at room temperature ( ⁇ 20 °C) and pH 6.5 - 7.0 without purging the pulp slurry with N 2 (i.e. in the presence of air/0 2 ), respectively, according to the general procedure A disclosed.
  • Table 7 lists the PC numbers of the original BTMP and the two 4-amino-TEMPO treated BTMP pulps versus the accelerated light exposure times. Treatment of the bleached TMP pulp with 4-amino-TEMPO at 60 °C or in the presence of air/oxygen is also effective in greatly improving the brightness stability of the pulp. TABLE 7
  • BTMP pulps can be dramatically improved by reaction with 1.0% or 0.2%
  • Table 9 shows the PC numbers of the original BTMP, the original BTMP coated with the UVA, the 4-amino-TEMPO treated BTMP, and the 4-amino-TEMPO treated BTMP coated with the UVA versus the accelerated light exposure times, respectively.
  • a nearly complete brightness stabilization of the BTMP pulp can be achieved by reaction of the pulp with 4-amino-TEMPO and then by coating the sheet made from the 4-amino-TEMPO-reacted pulp with the UVA.
  • BTMP pulps as the ones used in example 6 were treated with 1.0% (OD pulp) of 4-amino-TEMPO at room temperature and pH 5.5 - 6.0 for 0.5 hour according to the general procedure A disclosed, and treated with 1.0% (OD pulp) of 4-amino-TEMPO at 40 °C, and at 5% and 10% consistency (Cs.), respectively, according to the general procedure B disclosed.
  • Table 10 shows the PC numbers of the original BTMP, the three 4-amino-TEMPO treated BTMP pulps versus the accelerated light exposure times, respectively.
  • the reaction of 4-amino-TEMPO with pulps can be carried out at various consistencies for 0.5 or 3 hours to give pulps with much improved brightness stability.
  • TEMpyrrolidinylO provides a noticeable improvement of brightness stability to the pulp.
  • the total nitrogen content of the BTMP pulp treated with 3-amino-TEMpyrrolidinylO is 0.078% (on pulp), respectively, which corresponds to an attachment of 0.25% (on pulp) of the inhibitor to the BTMP pulp.
  • total nitrogen contents of the three treated BTMP pulps are 0.112%, 0.082% and 0.078%) (on pulp), respectively, which correspond to an attachment of 0.70%, 0.44%, and 0.40% (on pulp) of the inhibitor to the BTMP pulps, respectively.
  • BTMP pulps as the ones used in example 12 were treated with 1.0% (OD pulp) of l-hydroxyl-4-amino-2,2,6,6-tetramethylpiperidine sulfuric acid salt, 4-amino-TEMPOH-SA, and l-hydroxyl-4-amino-2,2,6,6- tetramethylpiperidine citric acid salt, 4-amino-TEMPOH-CA, both prepared from the reaction of 4-amino-TEMPO and the corresponding acids in ethanol according to a literature procedure [Sosnovsky and Cai, J. Org. Chem. 60_ 3414-3418, 1995], respectively, at room temperature and pH 6.5 - 7.0 according to the general procedure A disclosed.
  • a chelated spruce TMP pulps were bleached with 5% H 2 0 2 , 4% NaOH, 3% Na 2 Si0 3 and 0.05% Mg, (as MgS0 4 ) at 60 °C and 10 or 20% consistency in the absence (0.0%) and in the presence of 0.5% (OD pulp) of 4-amino-TEMPO or 1.0% (OD pulp) of 4-amino-TEMPOH-2HCl, respectively, according to the general procedure C disclosed.
  • Addition of 4-amino-TEMPO or 4-amino-TEMPOH-2HCl to alkaline peroxide bleaching of the pulps allows both the reaction of the fibre- reactive yellowing inhibitors with the pulps and the bleaching of the pulps to occur at the same time to give bleached pulps with much improved brightness stability.
  • the brightness stability of the BTMP pulp can be dramatically improved by treatment with 0.5% (OD pulp) of 4-amino-TEMPO, and significantly improved with 0.1% (OD pulp) of 4-amino-TEMPO.
  • the total nitrogen contents of the BTMP pulps treated with 0.5% and 0.1% of 4-amino-TEMPO are 0.103% and 0.052% (on pulp), respectively, which correspond to an attachment of 0.40% and 0.09% (on pulp) of 4-amino-TEMPO to the BTMP pulps, respectively.
  • Fully bleached kraft pulps containing, for example 20% of the 4-amino-TEMPOH-2HCl treated BCTMP pulps have much higher brightness stability than those containing same amounts of the untreated BCTMP pulps.
  • a much higher portion (e.g. 40%) of the treated BCTMP pulps than untreated BCTMP pulps (e.g. 10%) can be combined with fully bleached kraft pulps to give blended pulps with similar brightness stability.
  • a chelated spruce TMP was bleached with 5% H 2 0 2 , 4% NaOH, 3% Na 2 Si0 3 , 0.05% Mg (as MgS0 4 ) and, 0.0% (control) and 1.0% (OD pulp) of 4-amino-2,2,6,6-tetramethylpiperidine, respectively, at 60 °C and 20% consistency for 3 hours according to the general procedure C disclosed.
  • EXAMPLE 20 A chelated spruce TMP was bleached with 5% H 2 0 2 , 4% NaOH, 3% Na 2 Si0 3 , 0.05% Mg (as MgS0 4 ) and, 0.0% (control), 0.2% and 1.0% (OD pulp) of 4-amino-2,2,6,6-tetramethylpiperidine (abbreviated as amino- HALS hereafter), respectively, at 60 °C and 20%> consistency for 3 hours according to the general procedure C disclosed. A portion of a handsheet made from the control BTMP was coated with 1.0% (OD pulp) of amino- HALS dissolved in deionized water.
  • amino- HALS 4-amino-2,2,6,6-tetramethylpiperidine
  • a chelated spruce TMP was bleached with 5% H 2 0 2 , 4% NaOH, 3% Na 2 Si0 3 , 0.05% Mg (as MgS0 4 ) and 0.0% amino-HALS (control BTMP) at 60 °C and 20% consistency for 3 hours according to the general procedure C disclosed.
  • the same chelated spruce TMP was bleached with 5% H 2 0 2 , 4% NaOH, 3% Na 2 Si0 3 , 0.05% Mg (as MgS0 4 ) in the presence of 1.0% (OD pulp) of amino-HALS at 20% consistency and 60 °C, 70 °C and 80 °C, respectively, for 3 hours according to the general procedure C disclosed.
  • a chelated spruce TMP was bleached with 5% H 2 0 2 , 4% NaOH, 3% Na 2 Si0 3 , 0.05% Mg (as MgS0 4 ) and 0.0% amino-HALS (control BTMP) at 60 °C and 20% consistency for 3 hours according to the general procedure C disclosed.
  • the same chelated spruce TMP pulps were also bleached with 5% H 2 0 2 , 4% NaOH, 3% Na 2 Si0 3 , 0.05% Mg (as MgS0 4 ) and with 5% H 2 0 2 , 5% NaOH, 3% Na 2 Si0 3 , 0.05% Mg (as MgS0 4 ), respectively, in the presence of 1.0% amino-HALS at 60 °C and 20% consistency for 3 hours according to the general procedure C disclosed.
  • EXAMPLE 23 A chelated spruce TMP was bleached with alkaline hydrogen peroxide in two stages to give a control BTMP pulp (abbreviated as P1P2).
  • the first-stage (PI) bleaching was carried out using 2% H 2 0 2 , 1.5% NaOH, 3% Na 2 Si0 3 , 0.05% Mg (as MgS0 4 ) at 60 °C and 10% consistency for 3 hours according to the general procedure C disclosed.
  • the second-stage (P2) bleaching was carried out using 4% H 2 0 2 , 3% NaOH, 3% Na 2 Si0 3 , 0.05% Mg (as MgS0 4 ) at 60 °C and 20% consistency for 3 hours according to the general procedure C disclosed.
  • the same chelated spruce TMP were also bleached in two stages with the same amount of bleaching chemicals, temperature, time and consistency except that either the PI or P2-stage was carried out in the presence of 1.0% (OD pulp) of amino-HALS.
  • Addition of amino-HALS to either PI or P2-stage of a two-stage P1P2 bleaching of the spruce TMP pulps provides the bleached pulps with much improved brightness stability.
  • a chelated spruce TMP was bleached with alkaline hydrogen peroxide in two stages to give a control P1P2 pulp.
  • the PI bleaching was carried out using 2% H 2 0 2 , 1.5% NaOH, 3% Na 2 Si0 3 , 0.05% Mg (as MgS0 4 ) at 60 °C and 10% consistency for 3 hours according to the general procedure C disclosed.
  • the P2 bleaching was carried out using 4% H 2 O 2 , 3% NaOH, 3% Na 2 Si0 3 , 0.05% Mg (as MgS0 4 ) at 60 °C and 20% consistency for 3 hours according to the general procedure C disclosed.
  • the same chelated spruce TMP was also bleached in two stages in the same manner except that after the PI stage, the pulp was treated with 1.0% (OD pulp) of amino-HALS at room temperature and pH 6.5 - 7.0 for 3 hours according to the general procedure A disclosed.
  • Treatment of the PI pulp with amino-HALS before the P2 stage provides the P1P2 pulp with much improved brightness stability.
  • a chelated spruce TMP was bleached with 5% H 2 0 2 , 4% NaOH, 3% Na 2 Si0 3 , 0.05% Mg (as MgS0 4 ) at 60 °C and 20% consistency for 3 hours according to the general procedure C disclosed to give a control BTMP.
  • HALS HALS
  • a chelated spruce TMP was bleached with 5% H 2 0 2 , 4% NaOH, 3% Na 2 Si0 3 , 0.05% Mg (as MgS0 4 ) and, 0.0% (control) and 1.0% (OD pulp) of amino-HALS, respectively, at 60 °C and 20% consistency for 3 hours according to the general procedure C disclosed.
  • a portion of a handsheet made from the control BTMP and a portion of a handsheet made from the BTMP bleached in the presence of amino-HALS were coated with 1.0% of 2,4-dihydroxybenzophenone (abbreviated as DHBP) (Aldrich) dissolved in ethanol.
  • DHBP 2,4-dihydroxybenzophenone
  • a nearly complete brightness stabilization of the BTMP pulp can be achieved by bleaching of the pulp in the presence of amino-HALS and then by coating the sheet made from such a bleached pulp with an ultraviolet absorber such as DHBP.
  • OD pulp of 4-amino-TEMPO at room temperature and pH 6.5 - 7.0 according to the general procedure A disclosed, except without purging the pulp slurry with N 2 and that tap water (conductivity 25.2 :S/cm) and a mill process water such as a mill peroxide bleaching filtrate containing dissolving lignin (conductivity 3.47 x 10 :S/cm) were, respectively, used for the treatment and that tap water was used for the washing of the pulps.
  • tap water conductivity 25.2 :S/cm
  • a mill process water such as a mill peroxide bleaching filtrate containing dissolving lignin (conductivity 3.47 x 10 :S/cm) were, respectively, used for the treatment and that tap water was used for the washing of the pulps.
  • a same BTMP pulp was also reacted with 1.0% (OD pulp) of 4-amino- TEMPO in deionized water (conductivity 0.68 :S/cm) at room temperature and pH 6.5 - 7.0 according to the general procedure A disclosed, except without purging the pulp slurry with N 2 .
  • the invention is not to be limited to the brightness stabilization of the various mechanical wood pulps described, as the invention can be applied to other lignin-containing mechanical wood pulps of the same or different wood species or to other lignocellulosic materials such as wood products by those skilled in the art.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
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  • Polysaccharides And Polysaccharide Derivatives (AREA)

Abstract

L'invention concerne un nouveau procédé de production de matières lignocellulosiques stables à la lumière, et plus particulièrement, un procédé de production de pâtes mécaniques présentant une stabilité à la lumière nettement améliorée, ainsi que les pâtes à stabilité à la lumière améliorée obtenues et les papiers contenant ces pâtes. Ce nouveau procédé consiste à faire réagir des matières lignocellulosiques, telle que de la pâte thermomécanique blanchie, avec un inhibiteur du jaunissement sensible aux fibres hydrosoluble renfermant un groupe fonctionnel amine primaire ou secondaire (-NH2 ou -NHR) dans un milieu aqueux, ou avec un photostabilisant à blocage amine sensible aux fibres hydrosoluble renfermant un groupe fonctionnel amine primaire ou secondaire (-NH2 ou -NHR) dans un milieu de blanchiment utilisant du peroxyde d'hydrogène dans les séquences d'extraction alcaline ou dans un milieu aqueux avec un blanchiment ultérieur des matières dans un milieu de blanchiment utilisant du peroxyde d'hydrogène dans les séquences d'extraction alcaline. Des exemples de ces inhibiteurs de jaunissement sensibles aux fibres hydrosolubles et de ces photostabilisants à blocage amine sont les 4-amino-2,2,6,6-tetraméthylpipéridine-N-oxyl (4-amino-TEMPO) et 4-amino-2,2,6,6-tetraméthylpipéridine, respectivement, disponibles dans le commerce.
PCT/CA2001/001295 2000-09-18 2001-09-12 Matieres lignocellulosiques stables a la lumiere et leur production WO2002025007A2 (fr)

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WO2004038091A1 (fr) * 2002-10-23 2004-05-06 Pulp And Paper Research Institute Of Canada Matieres ligno-cellulosiques stables au traitement et a la lumiere et leur production
WO2004076419A1 (fr) * 2003-02-26 2004-09-10 Ciba Specialty Chemicals Holding Inc. Alcoxyamines steriquement encombrees et alcoxyamines hydroxy substituees hydrocompatibles
JP2016132678A (ja) * 2015-01-15 2016-07-25 Jnc株式会社 含窒素環化合物を含有する液晶組成物および液晶表示素子
CN113389085A (zh) * 2021-06-29 2021-09-14 王晓光 一种新型绿色环保化机浆浸泡添加剂及其用于秸秆制浆的方法

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US6789744B2 (en) * 2002-01-29 2004-09-14 Valeo Electrical Systems, Inc. Fluid heater with a variable mass flow path
US7550599B2 (en) * 2003-02-26 2009-06-23 Ciba Specialty Chemicals Corporation Water compatible sterically hindered alkoxyamines and hydroxy substituted alkoxyamines
US7125469B2 (en) * 2003-10-16 2006-10-24 The Procter & Gamble Company Temporary wet strength resins
FI20031904A (fi) * 2003-12-23 2005-06-24 Kemira Oyj Menetelmä lignoselluloosatuotteen muokkaamiseksi
EP1720931A4 (fr) * 2004-02-26 2007-08-08 Fpinnovations Polymeres a base d'epichlorohydrine contenant des groupes amino primaires utilises comme additifs dans la fabrication du papier
WO2006087269A1 (fr) * 2005-02-15 2006-08-24 Ciba Specialty Chemicals Holding Inc. Stabilisation de composites naturels
US7259218B2 (en) * 2005-02-17 2007-08-21 The Procter + Gamble Company Processes for making temporary wet strength additives
US8871922B2 (en) * 2009-03-20 2014-10-28 Fpinnovations Cellulose materials with novel properties

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WO1999005108A1 (fr) * 1997-07-23 1999-02-04 Ciba Specialty Chemicals Holding Inc. Inhibition du jaunissement de pate et de papier via des oxydes nitres et autres co-additifs

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US5529896A (en) * 1993-06-22 1996-06-25 Fuji Photo Film Co., Ltd. Silver halide photographic material
US5360515A (en) * 1993-08-25 1994-11-01 The Research Foundation Of The State University Of New York Method for reducing thermal and light-induced brightness reversion in lignin-containing pulps
WO1999005108A1 (fr) * 1997-07-23 1999-02-04 Ciba Specialty Chemicals Holding Inc. Inhibition du jaunissement de pate et de papier via des oxydes nitres et autres co-additifs

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004038091A1 (fr) * 2002-10-23 2004-05-06 Pulp And Paper Research Institute Of Canada Matieres ligno-cellulosiques stables au traitement et a la lumiere et leur production
US7384504B2 (en) 2002-10-23 2008-06-10 Fpinnovations Light-stable and process-stable lignocellulosic materials and their production
WO2004076419A1 (fr) * 2003-02-26 2004-09-10 Ciba Specialty Chemicals Holding Inc. Alcoxyamines steriquement encombrees et alcoxyamines hydroxy substituees hydrocompatibles
JP2016132678A (ja) * 2015-01-15 2016-07-25 Jnc株式会社 含窒素環化合物を含有する液晶組成物および液晶表示素子
CN113389085A (zh) * 2021-06-29 2021-09-14 王晓光 一种新型绿色环保化机浆浸泡添加剂及其用于秸秆制浆的方法

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