Classifications

• • 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
  • D21C9/005—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives organic compounds
• • 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
  • D21H21/143—Agents preventing ageing of paper, e.g. radiation absorbing substances
• • 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
  • D21H17/07—Nitrogen-containing compounds

Definitions

• the instant invention pertains to a method for preventing the loss of brightness and for enhancing resistance to yellowing in pulp or paper, particularly pulp or paper which still contains lignin, by the addition of N,N-dialkylhydroxylamines, an ester, amide or thio substituted N,N-dialkylhydroxylamine or N,N-dibenzylhydroxylamine, or their salts and other coadditives.
• High-yield and ultra-high yield wood pulps undergo rapid light-induced discoloration, particularly when they are exposed to near ultraviolet light (wave lengths 300-400 nm) in indoor fluorescent light and daylight. This characteristic restricts their use to short-life, low- value paper products.
• High-yield and ultra-high yield wood pulps can be bleached to a high level of whiteness. If this whiteness could be stabilized against discoloration, these bleached high-yield pulps could displace significant amounts of more expensive fully-bleached, low- yield chemical pulps.
• Phenoxy radicals are the key intermediates in the reaction mechanism.
• Several light-induced reactions have been proposed to account for their formation such as cleavage of the aryl ether bond of phenacyl aryl ether groups, or breakdown of ketyl radicals formed from saturated aryl-glycerol ⁇ -aryl ether structures in lignin.
• the phenoxy radicals are oxidized by other oxygen-centered radicals (alkoxy and perhydroxy) to form yellow chromophores.
• UV absorbers and hydrogen donor agents such as thiols, ascorbic acid, etc. help prevent the photoinduced discoloration of hydrogen peroxide bleached wood pulp, but that chain breakers such as hindered phenols and hindered amines (having >N-H or >N-CH 2 - moieties) had no or even a detrimental effect on preventing photoinduced discoloration.
• thermomechanical (TMP) and chemithermomechical (CTMP) pulps summarizes the state of the art in the thermal and light-induced yellowing of lignin-containing pulps such as thermomechanical (TMP) and chemithermomechical (CTMP) pulps, showing the seriousness of these undesirable effects discusses generally the then current prior art methods used to attack this problem.
• TMP thermomechanical
• CMP chemithermomechical
• WO 99/05108 describes a potential solution where the use of selected hindered amine nitroxides, hindered amine hydroxylamines or their salts in combination with selected UV absorbers and metal chelating agents is seen to prevent loss of brightness and to enhance resistance to yellowing in pulp or paper still containing lignin.
• Canadian Patent Application No. 2,164,394 and WO 97/36041 teach a multi- component system for modifying, degrading or bleaching lignin-containing materials.
• This system includes an oxidation catalyst as an essential component.
• the catalysts are selected enzymes such as oxidoreductases of classes 1 J J to 1.97.
• the system also includes a number of mediators which inter alia include lower N,N-dialkylhydroxylamines and N,N- dibenzylhydroxylamine.
• the instant invention describes another approach to this important problem where the use of N.N-dialkylhydroxylamine, an ester, amide or thio substituted N,N-dialkylhydroxyl- amine or N,N-dibenzylhydroxylamine or their salts in combination with selected coadditives also prevents the loss of brightness and enhances resistance to yellowing in pulp or paper, especially pulp or paper still containing lignin.
• the ester, amide or thio substituted N,N- dialkylhydroxylamines are described in United States Patent Nos. 4,612,393; 4,720,517 and 5,019,285.
• N,N-dialkylhydroxylamines, derivatives thereof or N,N-dibenzylhydroxyl- amine to pulp or paper either alone or in combinations with UV absorbers, metal chelating agents, fluorescent whitening agents and/or stabilizing polymers effectively achieves a distinctly improved light and thermal stability.
• Addition to a kraft pulp or paper, which may still contain traces of lignin leads to a distinct improvement of the light and thermal stability.
• N,N-dialkylhydroxylamines, derivatives thereof or N,N-dibenzylhydroxyl- amine to high-yield pulp or paper which still contain lignin either alone or in combinations with UV absorbers, metal chelating agents, fluorescent whitening agents and/or stabilizing polymers effectively achieves light and thermal stability which is similar to that found in papers made from kraft pulps.
• Hydroxylamines are known to be efficient free radical traps and may limit the production of o-quinones; UV absorbers limit photochemistry in the underlying substrate to which they are applied, and ultimately reduce the production of free radicals. UV absorbers and hydroxylamines are each effective at stemming some of the free radical chemistry leading to paper yellowing when used singly. However, when they are used together, hydroxylamines and UV absorbers can act synergistically to effectively stop photochemical yellowing of lignin containing papers.
• the hydroxylamines show enhanced inhibiting activity when combined with a metal chelating agent such diethylenetriaminepentaacetic acid or citric acid, or polymeric inhibitors such as polyethylene glycol. More particularly, the instant invention pertains to a composition having enhanced resistance to yellowing which comprises
• R T and R 2 are independently alkyl of 1 to 18 carbon atoms, alkyl of 1 to 18 carbon atoms substituted by a hydroxyl group; or benzyl;
• T, and T 2 are independently alkyl of 1 to 4 carbon atoms, phenyl, 3,5-di-tert-butyl-4- hydroxyphenyl, benzyl or -CH 2 COOH;
• ET and E 2 are independently -OE 3 , -NHE 3 or -NE 3 E 4 where E 3 and E 4 are independently hydrogen, alkyl of 1 to 4 carbon atoms or said alkyl substituted by one hydroxyl group; or
• X is an inorganic or organic anion, and the total charge of cations h is equal to the total charge of anions j.
• X is phosphate, phosphonate, carbonate, bicarbonate, nitrate, chloride, bromide, bisulfite, sulfite, bisulfate, sulfate, borate, formate, acetate, benzoate, citrate, oxalate, tartrate.
• acrylate polyacrylate, fumarate, maleate, itaconate, glycolate, gluconate, malate, mandelate, tiglate, ascorbate, polymethacrylate, a carboxylate of nitrilotriacetic acid, hydroxyethylethylenediaminetriacetic acid, ethylenediaminetetraacetic acid or of diethylene- triaminepentaacetic acid, a diethylenediaminetetraacetic acid or of diethylenetriaminepenta- acetic acid, an alkylsulfonate or an arylsulfonate.
• the hydroxylamine is N,N-dimethylhydroxylamine, N,N-diethylhydroxyl- amine, N,N-bis(2-hydroxypropyl)hydroxylamine, N,N-bis(3-hydroxypropyl)hydroxylamine, N,N-dioctadecylhydroxylamine, the N,N-dialkylhydroxylamine product made by the direct oxidation of N,N-di(hydrogenated tallow)amine, N,N-dibenzylhydroxylamine, N,N-bis(2- carboxyethyl)hydroxylamine or N,N-bis(benzylthiomethyl)hydroxylamine.
• the hydroxylamine is N,N-diethylhydroxylamine, N,N-bis(2-hydroxy- propyl)hydroxylamine, N,N-bis(3-hydroxypropyl)hydroxylamine or N,N-dibenzylhydroxyl- amine; most especially N,N-diethylhydroxylamine or its citric acid salt.
• salts of these hydroxylamines are also beneficial in producing the increase in brightness and the resistance to yellowing in pulp or paper, especially when still containing lignin.
• the effective stabilizing amounts of the hydroxylamine is 0.001 to 5% by weight based on the pulp or paper.
• the effective stabilizing amount is 0.005 to 4% by weight; preferably 0.01 to 4% by weight.
• the effective stabilizing amount of the coadditives is also 0.001 to 5% by weight based on the pulp or paper; preferably 0.005 to 3% by weight; most preferably 0.01 to 2% by weight.
• the instant compounds may additionally include an effective stabilizing amount of at least one stabilizer selected from the group consisting of the UV absorbers, the polymeric inhibitors, the sulfur containing inhibitors, the phosphorus containing compounds, the nitrones, the benzofuran-2-ones, fluorescent whitening agents, hindered amine hydroxylamines and salts thereof, hindered amine nitroxides and salts thereof, hindered amines and salts thereof and metal chelating agents.
• at least one stabilizer selected from the group consisting of the UV absorbers, the polymeric inhibitors, the sulfur containing inhibitors, the phosphorus containing compounds, the nitrones, the benzofuran-2-ones, fluorescent whitening agents, hindered amine hydroxylamines and salts thereof, hindered amine nitroxides and salts thereof, hindered amines and salts thereof and metal chelating agents.
• compositions which also include a UV absorber are especially preferred.
• the UV absorber is selected from group consisting of the benzotriazoles, the s-triazines, the benzophenones, the ⁇ -cyanoacrylates, the oxanilides, the benzoxazinones, the benzoates and the ⁇ -alkyl cinnamates.
• the UV absorber is a benzotriazole, an s-triazine or a benzophenone, most especially a benzotriazole UV absorber or benzophenone UV absorber.
• Typical and useful UV absorbers are, for example,
• compositions which additionally contain a polymeric inhibitor; preferably poly(ethylene glycol), polypropylene glycol), poly(butylene glycol) or poly(vinyl pyrrolidone).
• a polymeric inhibitor preferably poly(ethylene glycol), polypropylene glycol), poly(butylene glycol) or poly(vinyl pyrrolidone).
• compositions are those wherein the additional stabilizer is a sulfur containing inhibitor; preferably polyethylene glycol dithiolacetate, polypropylene glycol dithiolacetate, polybutylene glycol dithioacetate, 1 -thioglycerol, 2-mercaptoethyl ether, 2,2'thiodiethanol, 2,2'-dithiodiethanol, 2,2'oxydiethanethiol, ethylene glycol bisthioglycolate, 3-mercapto-1 ,2-propanediol, 2-(2-methoxyethoxy)-ethanethiol, glycol dimercaptoacetate, 3,3'-dithiopropionic acid, polyethylene glycol dithiol, polypropylene glycol dithiol, polybutylene glycol dithiol or ethylene glycol bis(mercaptoacetate).
• the additional stabilizer is a sulfur containing inhibitor
• compositions are those wherein the additional stabilizer is a phosphorus containing compound; preferably tris(2,4-di-tert-butylphenyl) phosphite, 2,2',2"- nitrilo[triethyl-tris(3,3',5,5'-tetra-tert-butyl-1 J'-biphenyl-2,2'-diyl) phosphite], bis(2,4-di-tert- butyl-6-methylphenyl) ethyl phosphite, sodium hydroxymethyl phosphinate, tetrakis(2,4-di- butylphenyl) 4,4'-biphenylenediphosphonite, tris(nonylphenyl) phosphite, bis(2,4-di-tert-butyl- phenyl) pentaerythrityl diphosphite, 2,2'-ethyliden
• compositions are those wherein the additional stabilizer is a benzo- furan-2-one; preferably 5,7-di-tert-butyl-3-(3,4-dimethylphenyl)-2H-benzofuran-2-one.
• compositions wherein the additional stabilizer is a metal chelating agent; preferably citric acid, keto acids, gluconates, heptagluconates, phosphates, phosphonates and aminocarboxylic acid chelates, such as ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), hydroxyethylethlenediaminetriacetic acid (HEDTA), nitrilotriacetic acid (NTA) and diethylenetriaminepentamethylenephosphonic acid (DTPMPA).
• EDTA ethylenediaminetetraacetic acid
• DTPA diethylenetriaminepentaacetic acid
• HEDTA hydroxyethylethlenediaminetriacetic acid
• NTA nitrilotriacetic acid
• DTPMPA diethylenetriaminepentamethylenephosphonic acid
• compositions contain a mixture of additional stabilizers such as a mixture of a UV absorber and polymeric inhibitor; or a mixture of a UV absorber and a sulfur containing compound; or a mixture of a UV absorber and a phosphorus containing compound; or a mixture of a UV absorber and a metal chelating agent; or a mixture of a polymeric inhibitor and a sulfur containing compound; or a mixture of a polymeric inhibitor and a phosphorus containing compound; or a mixture of a sulfur containing compound and a phosphorus containing compound; or a mixture of a UV absorber, a polymeric inhibitor and a sulfur containing compound; or a mixture of a UV absorber, a polymeric inhibitor and a phosphorus containing compound; or a mixture of a UV absorber, a polymeric inhibitor, a sulfur containing compound; or a mixture of a UV absorber, a polymeric inhibitor and a phosphorus containing compound; or a mixture of a UV absorber,
• compositions are those wherein the additional stabilizer is a mixture of a hindered amine hydroxylamine or hindered amine hydroxylamine salt with at least one other stabilizer selected from the group consisting of the UV absorbers, the polymeric inhibitors, the sulfur containing inhibitors, the phosphorus containing compounds, fluorescent whitening agents (optical brighteners), metal chelating agents and hindered amine nitroxides and salts thereof.
• the additional stabilizer is a mixture of a hindered amine hydroxylamine or hindered amine hydroxylamine salt with at least one other stabilizer selected from the group consisting of the UV absorbers, the polymeric inhibitors, the sulfur containing inhibitors, the phosphorus containing compounds, fluorescent whitening agents (optical brighteners), metal chelating agents and hindered amine nitroxides and salts thereof.
• compositions wherein the additional stabilizer is a mixture of a UV absorber, a polymeric inhibitor and a sulfur containing compound; or a UV absorber, a polymeric inhibitor and a phosphorus containing compound; or a UV absorber, a polymeric inhibitor and a metal chelating agent; or a UV absorber, a polymeric inhibitor, a sulfur containing compound and a phosphorus containing compound; or a UV absorber and a hindered amine nitroxide; or a UV absorber and a hindered amine hydroxylamine; or a UV absorber and a hindered amine hydroxylamine salt.
• (Sterically) hindered amine nitroxides, hydroxylamines or hydroxylamine salts are mainly the compounds disclosed in WO 99/05108 (see formulae A to EE and A* to EE * therein, especially compounds (a) to (mm)).
• compositions wherein the additional stabilizer is a mixture of a hindered amine hydroxylamine with at least one optical brightener such as 2,2'-[(1 ,1 '- diphenyl)-4,4'-diyl-1 ,2-ethenediyl]bis-benzenesuifonic, disodium salt ⁇ or bis[4,4'-(2- stilbenesulfonic acid)], disodium salt ⁇ which is TINOPAL SK (Ciba Specialty Chemicals).
• optical brightener such as 2,2'-[(1 ,1 '- diphenyl)-4,4'-diyl-1 ,2-ethenediyl]bis-benzenesuifonic, disodium salt ⁇ or bis[4,4'-(2- stilbenesulfonic acid)], disodium salt ⁇ which is TINOPAL SK (Ciba Specialty Chemicals).
• compositions are those wherein the compound of formula I, II, III, IA, IIA or IIIA is of low molecular weight or contains hydrophilic moieties or is both of low molecular weight and contains hydrophilic moieties.
• the instant invention also pertains to a process for preventing the loss of brightness and for enhancing resistance to yellowing of a pulp or paper, particularly a chemimechanical or thermomechanical pulp or paper which still contain lignin, or a chemical pulp or paper or kraft pulp or paper which still contains traces of lignin, which comprises
• the instant inhibitor additive system can be added to pulp or paper at a number of places during the manufacturing or processing operations. These include
• the precise location where the stabilizer additives should be added will depend on the specific equipment involved, the exact process conditions being used and the like. In some cases, the additives may be added at one or more locations for most effectiveness.
• stabilizer or other coadditives are not themselves “water-soluble", they may be dispersed or emulsified by standard methods prior to application. Alternatively, the stabilizer and/or coadditives may be formulated into a paper sizing or paper coating formulation.
• All additives are applied by syringe-injecting the appropriate weight % of additive combination in either an aqueous solution when the additive is water soluble, or a solution in 1 :1 ethanol/dioxane, onto bleached thermomechanical pulp (BTMP) or chemical (kraft) pulp brightness squares (4 cm x 4cm). The clamped sheets are allowed to air dry for one day.
• BTMP bleached thermomechanical pulp
• chemical (kraft) pulp brightness squares (4 cm x 4cm).
• the brightness of the handsheets is recorded before and after treatment by light exposure under controled intensity conditions.
• Accelerated testing is carried out by subjecting the treated sheets to accelerated light induced yellowing in a fan-cooled light box containing eight fluorescent lamps with a spectral maximum output at 5700 A with a total output approximately 43 times greater than normal office fluorescent lamps.
• the lamps are about ten inches away from the handsheets being illuminated.
• Ambient testing is carried out by placing the treated handsheets on a desk under normal cool-white fluorescent office lights at a nominal distance of six feet. ln both cases, ISO brightness is tracked as a function of photolysis time and converted to post color number (PC number) in the usual manner.
• PC number post color number
• Post color (PC) number is defined as follows:
• k and s are the absorption and scattering coefficients, respectively, and R in , is the value of ISO brightness.
• untreated BTMP handsheets When, using the ambient test conditions, untreated BTMP handsheets are compared to Kraft handsheets after 60 days, the BTMP handsheets have a PC number which is about 10 while the Kraft paper has a PC number which is about 0.39. The Kraft handsheets are clearly less yellow than untreated BTMP handsheets after exposure to ambient light.
• the incident light flux for the accelerated yellowing experiments is 43 times greater than normal office fluorescent lamps as measured by the A. W. Speery SLM- 110 digital light power meter.
• the brightness of the handsheets is tracked and compared to that of untreated sheets exposed in the same manner.
• the treated sheets exhibit significant resistance to yellowing as is seen below. Materials Used in the Examples
• Compound A is N,N-diethylhydroxylamine.
• Compound B is N,N-dibenzylhydroxyiamine.
• Compound C is N,N-dioctadecylhydroxylamine.
• Compound D is the N,N-dialkylhydroxylamine product made by the direct oxidation of N,N- di(hydrogenated tallow)amine.
• Compound E is tris(N,N-diethylhydroxylammonium) citrate.
• PEO is poly(ethylene glycol) of molecular weight 300.
• TINUVIN ⁇ 328 (Ciba) is 2-(2-hydroxy-3,5-di-tert-amylphenyl)-2H-benzotriazole.
• TINOPAL ® SK (Ciba) is 2,2'-[(1 ,r-diphenyl)-4,4'-diyl-1 ,2-ethenediylJ)is-benzenesulfonic, disodium salt ⁇ or bis[4,4'-(2-stilbenesulfonic acid)], disodium salt ⁇ .
• CIBAFAST ® W (Ciba) is 3-(2H-benzotriazol-2-yl)-4-hydroxy-5-sec-butylbenzenesulfonic acid, sodium salt.
• Compound F is N,N-bis(2-carboxyethyl)hydroxylamine.
• Compound G is N,N-bis(benzylthiomethyl)hydroxylamine.
• a BTMP sheet is treated with 1.0% by weight of N,N-diethylhydroxylamine (Compound A) and exposed to accelerated aging as described above.
• the treated sheet in exhibits a substantial inhibition of yellowing compared to the untreated control sheet as seen by inspection of the PC numbers given in the table below. Lower PC numbers indicate less color.
• a BTMP sheet is treated with 0.3% by weight of Compound B and 2.0% by weight of poly(ethylene glycol), molecular weight 300 (PEO). Again, the treated sheet exhibits an excellent resistance to yellowing as compared to the untreated control sheet.
• PEO poly(ethylene glycol), molecular weight 300
• a BTMP sheet is treated with 0.3% by weight of Compound C and 1.0% by weight of 2-(2-hydroxy-3,5-di-tert-amylphenyl)-2H-benzotriazole (TINUVIN ® 328, Ciba).
• the treated sheet shows surprisingly excellent resistance to yellowing especially in contrast to the untreated control sheet.
• a BTMP sheet is treated with 0.6% by weight of Compound D, 2.0% by weight of poly(ethylene glycol), molecular weight 300 (PEO), and 1.0% by weight of 2-(2-hydroxy-3,5- di-tert-amylphenyl)-2H-benzotriazole (TINUVIN ® 328, Ciba).
• the treated sheet shows extraordinary resistance to yellowing especially in contrast to the untreated control sheet.
• a BTMP sheet is treated with 0.3% by weight of Compound A and 1.0% by weight of TINOPAL ® SK. Again, the treated sheet exhibits an excellent resistance to yellowing as compared to the untreated control sheet.
• a BTMP sheet is treated with 0.3% by weight of Compound B and 1.0% by weight of CIBAFAST ® W.
• the treated sheet shows surprisingly excellent resistance to yellowing especially in contrast to the untreated control sheet.
• a BTMP sheet is treated with 0.33% and with 0.66% by weight of N,N-diethylhydroxyl- amine (Compound A) and 0.5% by weight of CIBAFAST ® W and then exposed to accelerated aging as described above.
• the treated sheet exhibits a substantial inhibition of yellowing compared to the untreated control sheet as seen by inspection of the PC numbers given in the table below. Lower PC numbers indicate less color.
• a BTMP sheet is treated with 0.33% and with 0.66% by weight of tris(N,N-diethyl- hydroxylammonium) citrate (Compound E) and 0.5% by weight of CIBAFAST ® W and then exposed to accelerated aging as described above.
• the treated sheet exhibits a substantial inhibition of yellowing compared to the untreated control sheet as seen by inspection of the PC numbers given in the table below. Lower PC numbers indicate less color.
• a BTMP sheet is treated with 1.0% by weight of N,N-bis(2-carboxyethyi)hydroxylamine (Compound F) and 1.0% by weight of CIBAFAST ® W and then exposed to accelerated aging as described above.
• the treated sheet exhibits a substantial inhibition of yellowing compared to the untreated control sheet.
• a BTMP sheet is treated with 1.0% by weight of N,N-bis(benzylthiomethyl)hydroxyl- amine (Compound G) and 1.0% by weight of CIBAFAST ® W and then exposed to accelerated aging as described above.
• the treated sheet exhibits a substantial inhibition of yellowing compared to the untreated control sheet.
• a kraft sheet is treated with 1.0% by weight of N,N-diethylhydroxylamine (Compound A) and exposed to accelerated aging as described above.
• the treated sheet in exhibits a substantial inhibition of yellowing compared to the untreated control sheet.
• a kraft sheet is treated with 0.3% by weight of Compound B and 2.0% by weight of poly(ethylene glycol), molecular weight 300 (PEO). Again, the treated sheet exhibits an excellent resistance to yellowing as compared to the untreated control sheet.
• PEO poly(ethylene glycol), molecular weight 300
• a kraft sheet is treated with 0.3% by weight of Compound C and 1.0% by weight of 2- (2-hydroxy-3,5-di-tert-amylphenyl)-2H-benzotriazole (TINUVIN® 328, Ciba).
• the treated sheet shows surprisingly excellent resistance to yellowing especially in contrast to the untreated control sheet.
• a kraft sheet is treated with 0.6% by weight of Compound D, 2.0% by weight of poly(ethylene glycol), molecular weight 300 (PEO), and 1.0% by weight of 2-(2-hydroxy-3,5- di-tert-amylphenyl)-2H-benzotriazole (TINUVIN® 328, Ciba).
• the treated sheet shows extraordinary resistance to yellowing especially in contrast to the untreated control sheet.
• a kraft sheet is treated with 0.3% by weight of Compound A and 1.0% by weight of TINOPAL ® SK. Again, the treated sheet exhibits an excellent resistance to yellowing as compared to the untreated control sheet.
• a kraft sheet is treated with 0.3% by weight of Compound B and 1.0% by weight of CIBAFAST ® W.
• the treated sheet shows surprisingly excellent resistance to yellowing especially in contrast to the untreated control sheet.
• a kraft sheet is treated with 0.33% and with 0.66% by weight of N,N-diethylhydroxyl- amine (Compound A) and 0.5% by weight of CIBAFAST ® W and then exposed to accelerated aging as described above.
• the treated sheet exhibits a substantial inhibition of yellowing compared to the untreated control sheet.
• a kraft sheet is treated with 0.33% and with 0.66% by weight of tris(N,N-diethyl- hydroxylammonium) citrate (Compound E) and 0.5% by weight of CIBAFAST® W and then exposed to accelerated aging as described above.
• the treated sheet exhibits a substantial inhibition of yellowing compared to the untreated control sheet.
• a kraft sheet is treated with 1.0% by weight of N,N-bis(2-carboxyethyl)hydroxylamine (Compound F) and 1.0% by weight of CIBAFAST® W and then exposed to accelerated aging as described above.
• the treated sheet exhibits a substantial inhibition of yellowing compared to the untreated control sheet.
• a kraft sheet is treated with 1.0% by weight of N,N-bis(benzylthiomethyl)hydroxylamine (Compound G) and 1.0% by weight of CIBAFAST® W and then exposed to accelerated aging as described above.
• the treated sheet exhibits a substantial inhibition of yellowing compared to the untreated control sheet.

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• Chemical & Material Sciences (AREA)
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• Wood Science & Technology (AREA)
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• Chemical And Physical Treatments For Wood And The Like (AREA)
• Anti-Oxidant Or Stabilizer Compositions (AREA)

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• 1999
  • 1999-10-11 JP JP2000578513A patent/JP2002528657A/ja active Pending
  • 1999-10-11 EP EP99953767A patent/EP1131483B1/en not_active Expired - Lifetime
  • 1999-10-11 AT AT99953767T patent/ATE253662T1/de not_active IP Right Cessation
  • 1999-10-11 CN CN99812516.4A patent/CN1324419A/zh active Pending
  • 1999-10-11 WO PCT/EP1999/007594 patent/WO2000024963A1/en not_active Application Discontinuation
  • 1999-10-11 CA CA002346211A patent/CA2346211A1/en not_active Abandoned
  • 1999-10-11 AU AU10346/00A patent/AU754737B2/en not_active Ceased
  • 1999-10-11 RU RU2001113262/12A patent/RU2222654C2/ru not_active IP Right Cessation
  • 1999-10-11 DE DE69912633T patent/DE69912633T2/de not_active Expired - Fee Related
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