MXPA01003954A - Inhibition of pulp and paper yellowing using hydroxylamines and other coadditives - Google Patents

Abstract

Pulps or papers, especially chemimechanical or thermomechanical pulps or papers, which still contain lignin, have enhanced resistance to yellowing when they contain an effective stabilizing amount of a N,N-dialkylhydroxylamine, an ester, amide or thio substituted N,N-dialkylhydroxylamine or N, N-dibenzylhydroxylamine or an ammonium salt thereof. This performance is often further enhanced by the presence of one or more coadditives selected from the group consisting of the UV absorbers, the polymeric inhibitors, the nitrones, the fluorescent whitening agents and metal chelating agents. Combinations of hydroxylamines or their salts, benzotriazole or benzophenone UV absorbers and a metal chelating agent are particularly effective. N,N-Diethylhydroxylamine and N, N-dibenzylhydroxylamine and their acid salts are surprisingly effective for this purpose.

Description

INHIBITION OF YELLOWING SIPPULP AND PAPER USING HYDROXYLAMINS AND OTHER COADITIVES FIELD OF THE INVENTION The present invention pertains to a method to prevent the loss of brightness and to increase the resistance to yellowing in the pulp or paper, particularly pulp or paper that still contains lignin, by the addition of N, N-dialkylhydroxylamines, a N, N-dialkylhydroxylamine or N, N-dibenzylhydroxylamine substituted with an ester, amide or thio or their salts and other * 1 * coadditives.

Background of the Invention 15 High performance and ultra high performance wood pulps undergo rapid color induced discoloration, particularly when exposed to near ultraviolet light (wavelengths of 300 to 400 nm) in indoor fluorescent light and daylight. This The characteristic restricts its use to short-life, low-value paper products. High performance and ultra high performance wood pulps can be bleached at a high level of whiteness. If this whiteness could be stabilized against discoloration, those bleached high performance pulps could displace quantities 1 ^ üfWBfr fi M Jñaíi ü a *** significant low-yield, fully bleached and more expensive chemical pulps. The discoloration is ascribed to the substantial lignin content of the high performance pulps which totals from about 20 to 30% by mass. Phenoxy radicals are the key intermediates in the reaction mechanism. It has been proposed that various light-induced reactions contribute to their formation, such as the cleavage of the aryl ether linkage from the phenacyl aryl ether groups, or the breaking down of ethyl radicals formed from saturated aryl glycerol-β-aryl ether structures in the lignin Phenoxy radicals are oxidized by other oxygen-centered radicals (alkoxy and perhydroxy) to form yellow chromophores. I. E. Arzkin et al., Khymya drevesiny (Chemistry of Wood), 1982, No. 2, 114 and A.D. Sergeev et al., Ibid, 1984, No. 5, 20 discloses that the use of iminoxyl radicals such as TEMPO (l-oxyl-2, 2,6,6,6-tetramethylperidine) is useful in the delignification of wood using the process (alkaline) of oxygen-soda of a stage, but does not mention or suggest any activity provided by the TEMPO on the prevention of discoloration induced by the light of the paper or pulp made of such treated wood. SAW. Khodyrev et al., Vysokomol soyed, A29, No. 3,616 (1987) [Polymer Sci, U.S.S.R., 29, No. 3, 688 (1987)] shows that oxidation photoinitiated by oxygen causes the ______________ __________ ^^^^^^^^ weathering of cellulosic textiles such as linen or cotton, and that the photostability of cellulose could be improved by photostabilizers such as. the UV absorbers, benzophenols and l-oxyl-2, 2, 6, 6-tetramet? l-4-h? droxip? perid? na. UV absorbers offer no protection, and are actually harmful. The authors noted that the stable nitroxyl radical interacts with alkyl radicals in cellulose to give its healthy stabilizing activity. There is no suggestion by the authors that this stabilizing activity could be applied successfully in wood pulp and / or the paper made from it. M-K Syler et al., J. Assn. Paper Pulp Tech, 29, 135 (1990) shows that selected metal salts such as magnesium sulfate and lower alkanoic acids inhibit color reversal in bleached pulp. P. Fornier de Violet et al., Cellulose Chem. Tech. 24, 225 (1990) shows that the use of UV absorbers and hydrogen donors such as thiols, ascorbic acid, etc., help prevent photo-induced discoloration. of the wood pulp bleached with hydrogen peroxide, but that chain destroyers such as hindered phenols and hindered amines (having portions> NH or> N-CH2-) did not have or even had a harmful effect on the prevention of photo-induced discoloration.

* * R. Agnemo et al., 6th International Symposium on Wood and Pulping Chemistry, Appita, 1991, confirmed that free hydroxyl radicals plus lignin lead to undesirable photoamarillation in pulp and paper. 5 S. Omori et al., J. Assn. Paper Pulp Tech, 48, 1388 (1993) describes the effect of antioxidants and UV absorbers on photoreversal and concludes that the combination of an antioxidant and UV absorber prevents color reversion and has a synergistic effect 0 on that activity. M. Paulsson et al., 8th International Symposium Wood and Pulping Chemistry, Helsinki, 1995, shows that efficient photostablization of unbleached paper or TMP pulp bleached with hydrogen peroxide can be achieved by acetylation. There have been numerous different methods proposed to inhibit the yellowing of mechanical pulps. These include: radical scavengers and antioxidants; UV protectors, elimination of chromophores or after their formation; chemical modification of lignin by alkylation or acetylation; polymeric inhibitors; and two types of co-additives used in combination. Z-H. Wu et al., Holzforschung, 4_8, (1994), 400 discusses the use of radical scavengers such as phenyl-N-tert-butylnitrone to reduce the formation of chromophores during the formation of mechanical pulp * and gives a stable pulp , clearest . C. Heitner, Chemistry of Brightness Reversal and It Control, Chapter 5, TAPPi; "Atlanta, 1996, pp. 183-211, summarizes the state of the art in thermal and photoinduced yellowing of lignin-containing pulps such as thermomechanical (TMP) and chemothermomechanical pulps (CTMP), showing the seriousness of these undesirable effects. In general, the prior art methods used hitherto to attack this problem include bleaching, the use of phosphites, UV absorbers, polyalkylene glycols and free radical scavengers such as ascorbic acid, thiols, thioethers, dienes. and aliphatic aldehydes and chelating agents such as ethylenediaminetetraacetic acid (EDTA). The author concluded that, although much progress has been made, there is still much to be done before a successful and practical solution to this loss of bright and yellowing can be found. undesirable of the pulp and / or lignin-containing paper, WO 99/05108 describes a potential solution, where it is observed that the of hindered amine nitroxides, hindered amine hydroxylamines or their salts in combination with selected UV absorbers and metal chelating agents prevents the loss of brilliance and increases the The "resistance to yellowing in the pulp or paper that still contains lignin." Canadian Patent Application No. 2,164,394 and WO 97/36041. They teach a multi-component system to modify, degrade or bleach lignin-containing materials This system includes an oxidation catalyst as an essential component Catalysts are selected enzymes such as oxidoreductases of classes 1.1.1 to 1.97. includes a number of mediators which, inter alia, include lower N, N-dialkylhydroxylamines and N, N-dibenzylhydroxylamine The present invention describes another method for this important problem, where the use of N, N-dialkylhydroxylamine, N, N -dialkylhydroxylamine or N, N-dibenzylhydroxylamine substituted with an ester, amide, or thio or their salts in combination with selected coadditives also prevents the request for brilliance and increases resistance to yellowing in the to pulp or paper, especially pulp or paper that still contains lignin. N, N-dialkylhydroxylamines substituted with an ester, amide or tio are described in U.S. Patent Nos. 4,612,393; 4,720,517 and 5,019,285.

Detailed Description of the Invention The addition of N, -dialkylhydroxylamines, derivatives thereof or N, N-dibenzylhydro-ylamine to the pulp or paper alone or in combination with UV absorbers, metal chelating agents, fluorescent whitening agents and / or stabilizing polymers effectively achieve a distinctly improved photo and thermostability. The addition to pulps or chemomechanical or thermomechanical papers, which still contain larger amounts of lignin, leads to a photo and thermostability which is similar to that found in papers made of kraft (chemical) pulps. Addition to a pulp or kraft paper, which may still contain traces of lignin, leads to a distinct improvement of the photo and thermostability. The addition of N, N-dialkylhydroxylamines, derivatives thereof or N, N-dibenzylhydroxylamine to high performance pulp or paper that still contains lignin alone or in combination with UV absorbers, metal chelating agents, fluorescent whitening agents and / or Stabilizing polymers effectively achieve photo and thermostability that is similar to that found in papers made from kraft pulps. It is known that hydroxylamines are efficient free radical scavengers and can limit the production of o-aquinones; UV absorbers limit photochemistry in 7 i > ^ ¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^ ___ 8.j_1, ^ = S_ > 2 ^^ _ fc? '_ Sa ^ -_? __ Aa __ ^ _-__ ii_: the underlying substrate to which they are applied, and' faith | 'ally reduce the production of free radicals. UV absorbers and hydroxylamines are each effective in containing some free radical chemical reactions that lead to yellowing * of the paper when used individually. However, when used together, hydroxylamines and UV absorbers can act synergistically to effectively stop photochemical yellowing of lignin-containing papers. Hydroxylamines exhibit greater inhibitory activity when combined with a metal chelating agent such as diethylenetriaminepentaacetic acid or nitric acid, or polymeric inhibitors such as polyethylene glycol. More particularly, the present invention pertains to a composition having greater resistance to yellowing, which comprises (a) a pulp or paper, especially a pulp or paper which still contains lignin, and (b) an effective stabilizing amount of N, N-dialkylhydroxylamine, N, N-diakylhydroxylamine or N, N-dibenzylhydroxylamine substituted by an ester, amide or thio of formulas I, II or III R? R2N-OH (I) (T? SCH2) (T2SCH2) N- OH (II) (ExCOCHsCHz) (E2COCH2CH2) N-OH (III) wherein Ri and R2 are independently alkyl of 1 to 18 carbon atoms, alkyl of 1 to 18 carbon atoms substituted by a hydroxyl group; or benzyl; Ti and T2 are independently alkyl of 1 to 4 carbon atoms, phenyl, 3,5-di-tert-butyl-4-hydroxyphenyl, benzyl or -CH2COOH; Ei and E2 are independently -0E3, -NHE3 or -NE3E4 where E3 and E4 are independently hydrogen, alkyl of 1 to 4 carbon atoms or alkyl substituted by a hydroxyl group; or an acid salt of formula IA, IIA or IIIA (R_R2N-0H) h + (? -) 3 (IA) [(T? SCH2) (T2SCH2) N-OH] h + (X ") -, (HA) [ (E? COCH2CH2) (E2COCH2CH2) N-OH] h + (X ") D (II IA) where X is an inorganic or organic anion, and the total charge of the cations h equals the total charge of the anions. Preferably, X is phosphate, phosphonate, carbonate, bicarbonate, nitrate, chlorine, bromine, bisulfite, sulfite, bisulfate, sulfate, borate, formate, acetate, benzoate, citrate, oxalate, tartrate, acrylate, polyacrylate, fumarate, maleate, itaconate, glycolate, gluconate, malate, mandelato, tiglato, ascorbate, polymethacrylate, a _L _ ^ _______._-_ 3_i_I _______ nitrilotriacetic acid carboxylate, hydroxyethylenediaminetriacetic acid, ethylenediaminetetraacetic acid or diethylenetriaminepentaacetic acid, an intetraacetic diethylenediand diethylenetriaminepenta-5-acetic acid an alkylsulphonate or an arylsulphonate. Preferably the hydroxylamine is N, N-dimethylhydroxylamine, N, N-diethylhydroxylamine, N, N-bis (2-hydroxypropyl) hydroxylamine, N, N-bis (3-hydroxypropyl) hydroxylamine, N, N-dioctadecylhydroxylamine, the product from N, N-dialkylhydroxylamine made by the direct oxidation of N, -bis (hydrogenated tallow) amine, N, N-dibenzylhydroxylamine, N, N-bis (2-carboxyethyl) hydroxylamine or N, N-bis (benzylthiomethyl) hydroxylamine. More preferably, the hydroxylamine is N, N-15 diethylhydroxylamine, N, N-bis (2-hydroxypropyl) hydroxylamine, N, N-bis (3-hydroxypropyl) hydroxylamine or N, N-dibenzylhydroxylamine; more particularly N, N-diethylhydroxylamine or its citric acid salt. It is shown that the salts of these hydroxylamines are also beneficial in producing the increase in brightness and resistance to yellowing in the pulp or paper, especially when it still contains lignin. The effective stabilizing amount of the hydroxylamine is from 0.001 to 5% by weight based on the pulp or paper. Preferably, the effective stabilizing amount is 0.005 to 4% by weight. Preferably 0. 01 to 4% by weight. When a coadjutant stabilizer is also present, the effective stabilizing amount of the coadditives is from 0.001 to 5% by weight based on the pulp or paper, preferably from 0.005 to 3% by weight; more preferably from 0.01 to 2% by weight. The compounds herein may additionally include an effective stabilizing amount of at least one stabilizer selected from the group consisting of UV absorbers, polymeric inhibitors, sulfur-containing inhibitors, phosphorus-containing compounds, nitrones, 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 that also include a UV absorber are especially preferred. The UV absorber is selected from the group consisting of benzotriazoles, s-triazines, benzophenones, a-cyanoacrylates, oxanilides, benzoxacinones, benzoates and a-alkyl cinnamates. Preferably, the UV absorber is a benzotriazole, an s-triazine or a benzophenone, more preferably . ^^ r ^^^^^ amau ¿~ a * t¡tot, i &? & j ^ i ____ _________ Mf_Í__i ____ ^ _ ^ _ ^ _ f tt special UV absorber or benzophenone UV absorber.

Typical and useful UV absorbers are, for example, 5-chloro-2- (2-hydroxy-3,5-di-tert-butylphenyl) -2H-benzotriazole; 2- (2-hydroxy-3,5-di-tert-butylphenyl) -2H-benzotriazole; 2- (2-hydroxy-3,5-di-tert-amylphenyl) -2H-benzotriazole; 2- (2-hydroxy-3,5-di-cumylphenyl) -2H-benzotriazole; 2- (2-hydroxy-3-a-cumyl-5-tert-octylphenyl) -2H-benzotriazole; 2- (2-hydroxy-5-tert-octylphenyl) -2H-benzotriazole; sodium salt of 2- (2-hydroxy-3-tert-butyl-5-methylphenyl) -2H-benzotriazole-5-sulfonic acid; 3-tert-butyl-4-hydroxy-5- (2H-benzotriazol-2-yl) hydrocinnamic acid; 3-tert-butyl-4-hydroxy-5- (2H-benzotriazol-2-yl) idroxinamate of 12-hydroxyl-3,6,9-trioxadodecyl; Octyl 3-tert-butyl-4-hydroxy-5- (2H-benzotriazol-2-yl) hydrocinnamate; 4, β-bis (2, -dimethylphenyl) -2- (4- (3-dodecyloxy * -2-hydroxypropoxy) -2-hydroxyphenyl) -s-triazine (* is a mixture of oxy isomers of C? 2-? 4); 12 4,6-bis (4-octyloxy-2-hydroxyphenyl) -st 4,6-diphenyl-2- (4-. {2- (l-ethylphenylcarbonyl) ethoxy) -2-hydroxyphenyl) - s-triazine; 2,4-dihydroxybenzophenone; 2, 2 ', 4, 4' -tetrahydroxy-5,5 '-disulphobenzophenone, disodium salt; 2-hydroxy-4-octyloxybenzophenone; 2-hydroxy-4-dodecyloxybenzophenone; 2,4-dihydroxybenzophenone-5-sulfonic acid and salts thereof; 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid and salts thereof; sulfonate 2,2'-dihydroxy-4,4'-dimethoxybenzophenone-5'-disodium; and 3- (2H-benzotriazol-2-yl) -4-hydroxy-5-sec-butylbenzenesulfonic acid, sodium salt (CIBAFAST W). Other preferred compositions are those which additionally contain a polymeric inhibitor; preferably poly (ethylene glycol), poly (propylene glycol), poly (butylene glycol) or poly (vmilpyrrolidone). Other preferred compositions are still those where the additional stabilizer is a sulfur-containing inhibitor; dithioacetate preferably polyethylene glycol, polypropylene glycol dithioacetate, polybutylene glycol dithioacetate, 1-tioglicejn.l, 2-mercaptoethyl ether, 2, 2 'thiodiethanol, 2, 2' dithio < ü Bsnol, 2, 2 '-oxidietantiol, bistioglicolato ethylene glycol, 3-mercapto-l, 2-propanediol, 2- (2-methoxyethoxy) -etantiol, glycol dimercaptoacetate, 3-, 3' -ditiopropiónico, polyethylene glycol dithiol , propylene glycol dithiol, polybutylene glycol dithiol or bis (mercaptoacetate) of ethylene glycol. Other preferred compositions are those where the additional stabilizer is a phosphorus-containing compound; preferably tris (2,4-tert-butylphenyl), 2,2 ', 2"-nitrile [triethyl-tris (3,3', 5, 5'-tetraether-butyl-1,1 ') phosphite. -biphenyl-2, 2 '-diil) phosphite] phosphite, bis (2, 4-di-tert-butyl-6-methylphenyl) ethyl, hydroxymethyl sodium phosphinate, 4, 4' -bifenilnfosfito tetrakis (2, - di-butylphenyl) phosphite, tris (nonylphenyl) phosphite, bis (2,4-tert-butylphenyl) pentaerythrityl 2,2'-ethylidenebis fluorophosphite (2, 4-di-tert-butylphenyl) phosphite or 2, 6-tri-tert-butylphenyl phosphite of 2-butyl-2-ethylpropan-1,3-diyl Other preferred compositions are still those in which the additional stabilizer is a benzo-furan-2-one, preferably 5, 7 di-tert-butyl-3- (3,4-dimethylphenyl) -2H-benzofuran-2-one Other preferred compositions are still those where the additional stabilizer is a metal chelating agent, preferably citric acid, keto acids, gluconates , heptagluconates, phosphonates, phosphates, phosphonates and aminocarboxylic acid chelates, such as mo ethylenediaminetetraacetic acid (EDTA), dietilentriammo pentaacetic acid (DTPA), hydroxyethylenediaminetriacetic acid (HEDTA), nitrilotriacetic acid (NTA) and diethylenetriaminepentamethylenephosphonic acid (DTPMPA). Some preferred compositions contain a mixture of additional stabilizers such as a mixture of a UV absorber and a 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 and a phosphorus-containing compound; or a mixture of a UV absorber, a polymeric inhibitor and a metal chelating agent.

Some preferred compositions are those wherein the additional stabilizer is a mixture of hindered amine hydroxylamine or hindered amine hydroxylamine salt with at least one other stabilizer selected from the group consisting of UV absorbers, polymeric inhibitors, sulfur-containing inhibitors, phosphorus-containing compounds, fluorescent whitening agents (optical brighteners), metal chelating agents and hindered amine nitroxides and salts thereof. Also preferred are 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 hindered amine hydroxylamine; or a UV absorber and a hindered amine hydroxylamine salt. Amine nitroxides, hydroxylamines or hydroxylamine salts of hindered amine (spherically) are mainly the compounds described in WO 99/05108 (see formulas A to EE and A * to EE * therein, especially compounds (a) to (mm)). 16 The following stabilizers are preferred compositions where the additional stabilizer is a mixture of a hydroxylamine of hindered amine with met? p? an optical brightener such as 2, 2 '- [(1,1'-difeml) -4,4'-diyl-1,2-ethanediyl] bisbenzenesulfonic acid, sodium salt (or bis [4,4' acid] - (2- stybensulphonic)], disodium salt) which is TINOPAL SK (Ciba Specialty Chemicals) Preferably the compositions are those where a compound of formula I, II, III, IA, HA or IIIA is of low molecular weight or contains hydrophilic portions or both are of low molecular weight and contains hydrophilic portions The present invention also pertains to a process for preventing the loss of brightness and for increasing the yellowing resistance of a pulp or paper, particularly a pulp or chemomechanical paper or thermomechanical which still contains lignin, or a pulp or mechanical paper or pulp or kraft paper that still contains traces of lignin, which comprises treating the pulp or paper with an effective stabilizing amount in a compound of formula I, II or III, formula IA, HA, or IIIA as described earlier. The additive inhibitor system herein can be added to pulp or paper at a number of locations during manufacturing or processing operations. Those include a. on a suspension of pulp in the latency chest; b. on a pulp suspension in or after the bleaching step in a storage, mixing or transfer chest; c. on the pulp during or after bleaching, washing and dehydration followed by roller drying or evaporation; d. before or after the cleaners; and. before or after a ventilation pump to the head box of the paper machine; F. to the white water of the paper machine; g. to the silo or guardatodo; h. in the pressing section using a gluing press, coater or spray device; i. in the drying section using a gluing press, reverter or spray device; j. on the calandria using a box of discs; k. on paper in a coating device outside the machine or gluing press; and / or i. in the bordering control unit. -jft ^ ftirt - ^ "^^^ -'- Clearly, the precise location where the stabilizing additives should be added will depend on the specific equipment involved, the exact conditions of the process being used and the like.In some cases, the additives may be added in-tíno or more places for greater effectiveness.If the stabilizer or other coadditives are not in themselves "water soluble", they can be dispersed or emulsified by standard methods before application. Alternatively, the stabilizer and / or co-additives may be formulated in a paper sizing or paper coating formulation. The following examples are for illustrative purposes only and should not constitute the limit to the present invention in any way whatsoever.

Treatment of Handmade Sheets All additives are applied by syringe injection of the appropriate weight% of the additive combination in either an aqueous solution when the additive is soluble in water, or a solution in ethanol / dioxane 1: 1 , on squares (4 cm x 4 cm) of bleached thermomechanical pulp (BTMP) or bright chemical pulp (kraft). Pressed sheets are allowed to air dry for a day. 19 ? _fi_fft '- "; _.._: ¿_ ^ .___; __, i _ ^ _ * _ Í_ The brightness of the handmade leaves is recorded before and after treatment by exposure to light under conditions of Controlled intensity The accelerated test is carried out by subjecting the 5 treated sheets to induced yellowing by accelerated light in a light box cooled with a fan containing eight fluorescent lamps with a maximum spectral output at 5700 Á with an output approximately 43 times higher that the office fluorescent lamps.The lamps are about 10 inches (25.4cm) away from the handmade sheets that are being lit.The environmental tests are carried out by placing the handmade sheets treated on a desk under the lights of the office fluorescent white, cold, normal at a nominal distance of 6 feet (15.2 cm) In both cases, the ISO brightness is followed as a function of photolysis time and converted to number poscolor (PC number) and the usual way. The postcolor number (PC) is defined as follows: 20 PC = [(k / s) ofSpues- (k / s) before] x 100k / s = (1 - R? Nf) 2/2 R? Nf where kys are the absorption and diffraction coefficients, respectively, and R? nf is the value of the ISO brightness. twenty • -ftjJtftfr? ? ^^ - «- ¿________ * _____-_. * ,, __. F .__ r_fe ___ ¿__a¡ gg ^ g ^ igiígg ^ The relationship between R? Nf and the chromophore concentration is not linear, while the PC number it is approximately linearly related to the concentration of the chromophore in the sample. Low PC numbers are desirable since they indicate less yellowing. When, using the environmental test conditions, untreated BTMP hand-made sheets are compared to kraft hand-made sheets after 60 days, the BTMP hand-made sheets have a PC number which is approximately 10 while the paper Kraft has a PC number which is approximately 0.39. Hand-made kraft leaves are clearly less yellow than BTMP handmade leaves after exposure to ambient light. The incident light flux for the accelerated yellowing experiments (Example 1-10) is 43 times larger than that of normal office fluorescent lamps as measured by the digital light power meter A. W. Speeru SLM-110. The brilliance of the handmade leaves is followed and compared so that the untreated leaves are exposed in the same way. The treated leaves exhibit significant yellowing resistance as described below.

Materials Used in the Examples Compound A is N, N-diethylhydroxylamine. Compound B is N, N-dibenzylhydroxylamine. Compound C is N, N-dioctadecylhydroxylamine. Compound D is the product of N, N-dialkylhydroxylamine made by the direct oxidation of N, N-bis (hydrogenated tallow) amine. Compound E is tris (N, N-butylhydroxylammonium) citrate. PEO is poly (ethylene glycol) with a molecular weight of 300. TINUVIN®328 (Ciba) is 2- (2-hydroxy-3,5-di-ter-amylphenyl) -2H-benzotriazole. TINOPAL® SK (Ciba) is 2, 2 '- [(1,1' -diphenyl) -4, '-diyl-1,2-ethanediyl] bis-benzenesulfonic, disodium salt. { or bis [acid, '- (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, -bis (2-carboxyethyl) hydroxylamine. Compound G is N, N-bis (benzylthiomethyl) hydroxylamine. 22 Example 1 Accelerated Yellowing with High Density Lamps, Pulp Bleached Thermomechanics (BTMP) A BTMP was treated. with 1.0% by weight of N, N-diethylhydroxylamine (Compound A) and exposed to accelerated aging as described above. The treated ho show a substantial inhibition of yellowing compared to the untreated control sheet as observed by the inspection of the PC numbers given in the following table. Minor PC numbers indicate less color.

Compound Time A Control Hours PC Number PC Number 0 0 0 23. 6 2.2Í 5.14 29.4 2.86 6.07 48. 7 5.00 9.01 97.8 10.40 15.75 120.3 12.95 18.54 144.0 15.77 21.48 23 Compound Time A Control Hours PC Number PC Number 172. 2 19.10 24.95 EXAMPLE 2 Accelerated Yellowing with High Density Lamps A BTMP sheet was treated with 0.3% by weight of Compound B and 2.0% by weight of poly (ethylene glycol), with a molecular weight of 300 (PEO). Again, the treated sheet exhibits excellent resistance to yellowing compared to the untreated control sheet.

EXAMPLE 3 Accelerated Yellowing with High Intensity Lamps A BTMP sheet was treated with 0.3% by weight of Compound C and 1.0% by weight of 2- (2-hydroxy-3,5-d-ether-amylphenyl) - 2H-benzotriazole (TINUVIN® 328, (Ciba) The treated sheet surprisingly shows excellent resistance to yellowing, especially in contrast to the untreated control sheet. 24 M_Bi ___ ^^ »^^^^^^^^^^ Example 4 Accelerated Yellowing with High Density Lamps A BTMP sheet was treated with 0.6% by weight of Compound D, 2.0% by weight of poly (ethylene glycol), with a molecular weight of 300 (PEO), and 1.0% of 2- (2-hydroxy-3,5-di-tert-amylphenyl) -2H-benzotriazole (TINUVIN® 328, (Ciba) .The treated leaf shows extraordinary resistance to yellowing , especially in contrast to the untreated control sheet.

Example 5: Accelerated Yellowing with High Density Lamps A BTMP sheet was treated with 0.3% by weight of Compound A and 1.0% by weight of TINOPAL® SK. Again, the treated sheet shows excellent resistance to yellowing, especially in contrast to the untreated control sheet.

EXAMPLE 6 Accelerated Yellowing with High Density Lamps A BTMP sheet was treated with 0.3% by weight of the Compound B and 1.0% by weight of CIBAFAST® W. The treated sheet surprisingly shows excellent resistance to yellowing, especially in contrast to the untreated control sheet.

Example 7 A BTMP was treated with 0.33% and 0.66% by weight N, N-diethylhydroxylamine (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 observed by the inspection of PC numbers given in the following table. Minor PC numbers indicate less color.

Time 0.5% of W 0.5% of W in 0.66% of A 0.33% of A Control Days number PC number PC number PC 0 0 0. 85 l.lí 1.43 2.80 1. 84 2.55 2.75 4.71 2. 79 3.90 4.24 6.94 3. 83 5.46 5.99 8.91 .75 7.05 7.63 11.03 .77 8.63 9.23 13.08 .81 9.92 10.56 14.42 Time 0.5% of W 0.5% of W in 0.66% of A 0.33% of A Control Days number PC number PC number PC 7. 75 10.93 11.62 15.57 8. 74 11.91 12.53 16.38 Example 8 A BTMP sheet with 0.33% and 0.66% by weight tris (N, N-diethylhydroxylammonium) citrate (Compound E) and 0.5% by weight of CIBAFAST® W was treated 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 observed by the inspection of PC numbers given in the following table. Minor PC numbers indicate less color.

Time 0.5% of W 0.5% of W in 0.66% of E 0.33% of E Control Days number PC number PC number PC 0 0 0. 85 0.94 1.26 2.80 Time 0.5% of W 0.5% of W in 0.66% of E 0.33% of E Control Days number PC number PC number PC 1. 84 2.10 2.54 4.71 3. 43 3.94 6.94 3. 83 5.31 5.66 8.91 4. 75 6.97 7.03 11.03 . 77 8.43 .71 13.08 6. 81 9.98 10.08 14.42 7. 75 10.78 10.96 15.57 8. 74 11.91 12. L 16.38 Example 9 A BTMP sheet with 1.0 wt.% N, N-b? S (2-carboxyethyl) hydroxylamine (Compound F) and 1.0 wt.% Of CIBAFAST® W was treated and then exposed to accelerated aging as described above. The treated sheet exhibits a substantial inhibition of yellowing compared to the untreated control sheet. 28 s * "-Example 10 A BTMP sheet with 1.0 wt% N, N-bis (benzylthiomethyl) hydroxylamine (Compound G) and 1.0 wt% of CIBAFAST® W was treated and then exposed to accelerated aging as described above . The treated sheet exhibits a substantial inhibition of yellowing compared to the untreated control sheet. The following examples 11-20 describe accelerated yellowing tests with high density lamps conducted on chemical pulp (kraft): Example 11 A kraft sheet was treated with 1.0% by weight of N, N-diethylhydroxylamine (Compound A) and exposed to accelerated aging as described above. The treated leaf exhibits a substantial inhibition of the taper compared to the untreated control sheet.

Example 12 A kraft sheet was treated with 0.3% by weight of Compound B and 2.0% by weight of poly (ethylene glycol), with a molecular weight of 300 (PEO). Again, the treated sheet exhibits excellent resistance to yellowing compared to the untreated control sheet.

Example 13 A kraft sheet was 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 yarn surprisingly shows excellent resistance to yellowing, especially in contrast to the untreated control sheet.

Example 14 A kraft sheet was treated with 0.6% by weight of the Compound D, 2.0% by weight of poly (ethylene glycol), with a molecular weight of 300 (PEO), and 1.0% of 2- (2-hydroxy-3,5-di-ter-amylphenyl) -2H-benzotriazole ( TINUVIN® 328, Ciba). The treated leaf shows extraordinary resistance to yellowing, especially in contrast to the untreated control sheet.

Example 15 A kraft sheet was treated with 0.3% by weight of Compound A and 1.0% by weight of TINOPAL® SK. Again, the treated sheet shows excellent resistance to yellowing, especially compared to the untreated control sheet.

Example 16 ', A kraft sheet was treated with 0.3% by weight of the Compound B and 1.0% by weight of CIBAFAST® W. The treated sheet surprisingly shows excellent resistance to yellowing, especially in contrast to the untreated control sheet.

Example 17 A kraft sheet with 0.33% and 0.66% by weight N, N-diethylhydroxylamine (Compound A) and 0.5% by weight of CIBAFAST® W was treated and then exposed to accelerated aging as described above. The treated sheet exhibits a substantial inhibition of yellowing compared to the untreated control sheet.

Example 18 A kraft sheet with 0.33% and 0.66% by weight tris (N, N-diethylhydroxylammonium) citrate (Compound E) and 0.5% by weight of CIBAFAST® W was treated and then exposed to accelerated aging as described above. The treated sheet exhibits a substantial inhibition of yellowing compared to the untreated control sheet. 31 Example 7 A kraft sheet with 1.0 wt.% N, Nb? s (2-carboxyethyl) hydroxylamine (Compound F) and 1.0 wt.% of CIBAFAST® W was treated? and then exposed to accelerated aging as described above. The treated leaf exhibits a substantial inhibition of the taper compared to the untreated control sheet.

Example 20 A kraft sheet with 1.0 wt% N, N-bis (benzylthiomethyl) hydroxylamine (Compound G) and 1.0 wt% of CIBAFAST® W was treated and then exposed to accelerated aging as described above. The treated sheet exhibits a substantial inhibition of yellowing compared to the untreated control sheet. 32 ¡a_j__a t a_l_Mí «_rt _a« i_te.? - - ___- ¿¿s_Í •? La?? M¿ ^? ¿SXti 2

Claims (12)

1. A composition having a loss reduced to brightness and greater resistance to yellowing, characterized in that it comprises (a) a pulp or paper, and (b) an effective stabilizing amount of N, N-dialkylhydroxylamine, N, N-diakylhydroxylamine or N, N -dibenzylhydroxylamine substituted by an ester, amide or thio of formulas I, II or III R1R2N-OH (I) (T? SCH2) (T2SCH2) N-OH (II) (E? COCH2CH2) (E2COCH2CH2) N-OH (III ) where Ri and R2 are independently alkyl of 1 to 18 carbon atoms, alkyl of 1 to 18 carbon atoms substituted by a hydroxyl group; or benzyl; Ti and T2 are independently alkyl of 1 to 4 carbon atoms, phenyl, 3,5-di-tert-butyl-4-hydroxyphenyl, benzyl or -CH2COOH; Ei and E2 are independently -OE3, -NHE3 or -NE E4 where E3 and E4 are independently hydrogen, alkyl of 1 to 4 carbon atoms or alkyl substituted by a hydroxyl group; or an acid salt of formula IA, HA or HIA 33 'im-ffi ^? iji (R? R2N-OH) h + (X -) -, (IA) [(T? SCH2) (T2SCH2) N-OH] h + (X ") D (HA) [(E! COCH2CH2) (E2COCH2CH2) N-OH] h + (X ") D (IIIA) where. . { Ri, R2, Ti, T2, Ei, E2 are as described above. X is an inorganic or organic anion, and the total charge of the cations h is equal to the total charge of the anions j, provided that the composition contains non-aggregated enzyme.

2. The composition according to claim 1, characterized in that the component (a) is pulp or paper which still contains lignin.

3. The composition according to claim 1, characterized in that the component (a) is chemimechanical pulp or paper or thermomechanical or kraft.

4. The composition according to claim 1, characterized in that in formula IA, HA or HIA X is phosphate, phosphonate, carbonate, bicarbonate, nitrate, chlorine, bromine, bisulfite, sulfite, bisulfate, sulfate, borate, formate, acetate. , benzoate, citrate, oxalate, tartrate, acrylate, polyacrylate, fumarate, maleate, itaconate, glycolate, gluconate, malate, mandelate, tiglato, ascorbate, polymethacrylate, an acid carboxylate 3. 4 nitrilotriacetic acid, hydroxyethylethylenediaminetriacetic acid, ethylenediaminetetraacetic acid or diethylenetriaminepentaacetic acid, a diethylene diamine tetraacetic acid or diethylenetriamine pentane acetic acid an alkylsulphonate or an arylsulfonate.

The composition according to claim 1, characterized in that component b is N, N-dimethylhydroxylamine, "N, N-diethylhydroxylamine, N, N-bis (2-hydroxypropyl) hydroxylamine, N, -bis (3-hydroxyl) propil) 10 hydroxylamine, N, N-dioctadecylhydroxylamine, the product of N, N-dialkylhydroxylamine 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, or an acid salt 15 corresponding.

The composition according to claim 1, characterized in that it additionally includes an effective stabilizing amount of at least one coaditr selected from the group consisting of UV absorbers, Polymeric inhibitors, sulfur-containing inhibitors, phosphorus-containing compounds, nitrones, benzofuran-2-ones, fluorescent whitening agents, hindered amine hydroxylamines and salts thereof, hindered amine nitroxides and salts thereof, amines 25 hindered and salts thereof and metal chelating agents. 35 7.

The composition according to claim 6, characterized in that the additional stabilizer is UV absorber is selected from the group consisting of benzotriazoles, s-triazines, benzophenones, a-cyanoacrylates, oxanilides, benzoxacinones, benzoates and a-alkyl cinnamates; a polymeric inhibitor selected from poly (ethylene glycol), poly (propylene glycol), poly (butylene glycol) or poly (vinylpyrrolidone); a sulfur-containing inhibitor selected from the group consisting of polyethylene glycol dithioacetate, polypropylene glycol dithioacetate, polybutylene glycol dithioacetate, 1-thioglycerol, 2-mercaptoethyl ether, 2,2 'thiodiethanol, 2,2' -dithiodiethanol, 2, 2'-oxidietantiol, ethylene glycol bistioglycolate, 3-mercapto-l, 2-propanediol, 2- (2-methoxyethoxy) -ethiol, glycol dimercaptoacetate, 3, 3'-dithiopropionic acid, polyethylene glycol dithiol, polypropylene glycol dithiol, polybutylene glycol dithiol and bis (mercaptoacetate) of ethylene glycol; and / or a phosphorus-containing compound selected from the group consisting of tris (2,4-di-tert-butylphenyl) phosphite, 2,2 ', 2"-nitrile [triethyl-tris (3,3', 5, 5 '-tetra-tert-butyl-1, 1' -biphenyl-2,2'-diyl) phosphite], tris (2,4-di-tert-butyl-6-ethylphenyl) phosphite phosphite, sodium hydroxymethyl phosphinate, 4,4'-tetracis (2, -di-butylphenyl) biphenylenediphosphonate, 36 _ ^ _ ^ ___ &___ J ^^ - ^ MA____ tris (nonylphenyl) phosphite, bis (2,4-di-tert-butyl-phenyl) pentaerythrityl diphosphite, 2,2'-ethylidenebis (2, -di-) fluorophosphite tert-butylphenyl) and 2-butyl-2-ethylpropan-l, 3-diyl-2,, 6-tri-tert-butylphenylphosphite.

The composition according to claim 6, characterized in that the additional stabilizer is a mixture containing two of the following components: a UV absorber and a polymeric inhibitor; a UV absorber and a sulfur-containing compound; a UV absorber and a phosphorus-containing compound; a UV absorber and a metal chelating agent; a polymeric inhibitor and a sulfur-containing compound; a polymeric inhibitor and a phosphorus-containing compound; a sulfur-containing compound and a phosphorus-containing compound; a UV absorber and a hindered amine.

The composition according to claim 1, characterized in that the effective stabilizing amount of the hydroxylamine or hydroxylamine salt of component b is 0.001 to 5% by weight based on the pulp or paper.

10. The composition according to claim 7, characterized in that the effective stabilizer amount of a coaditrant is 0.001 to 5% by weight based on the pulp or paper.

11. A process to prevent the loss of brightness and to increase resistance to yellowing of the pulp or paper, characterized in that it comprises treating the pulp or paper with an effective stabilizing amount of a hydroxylamine compound of formula I, II or III or hydroxylamine salt of formula IA, HA c HIA according to claim 1.

12. The use of a hydroxylamine compound of formula I, II or III or hydroxylamma salt of formula IA, HA or HIA according to claim 1 to stabilize pulp or paper against the loss of brightness and yellowing.