NO145344B - MULTIPLE-STEP PROCEDURE FOR CHLOROUS WHITENING OF CELLULOSE - Google Patents
MULTIPLE-STEP PROCEDURE FOR CHLOROUS WHITENING OF CELLULOSE Download PDFInfo
- Publication number
- NO145344B NO145344B NO754077A NO754077A NO145344B NO 145344 B NO145344 B NO 145344B NO 754077 A NO754077 A NO 754077A NO 754077 A NO754077 A NO 754077A NO 145344 B NO145344 B NO 145344B
- Authority
- NO
- Norway
- Prior art keywords
- cellulose
- bleaching
- peroxide
- alkali
- weight
- Prior art date
Links
- 229920002678 cellulose Polymers 0.000 title claims description 24
- 239000001913 cellulose Substances 0.000 title claims description 22
- 238000000034 method Methods 0.000 title claims description 19
- 230000002087 whitening effect Effects 0.000 title 1
- 238000004061 bleaching Methods 0.000 claims description 31
- 150000002978 peroxides Chemical class 0.000 claims description 13
- 239000003513 alkali Substances 0.000 claims description 11
- 241000294754 Macroptilium atropurpureum Species 0.000 claims description 6
- 238000006298 dechlorination reaction Methods 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 4
- 235000010980 cellulose Nutrition 0.000 description 19
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 8
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 6
- 238000005660 chlorination reaction Methods 0.000 description 6
- 239000000460 chlorine Substances 0.000 description 6
- 229910052801 chlorine Inorganic materials 0.000 description 6
- 239000000126 substance Substances 0.000 description 5
- 239000002351 wastewater Substances 0.000 description 5
- WQYVRQLZKVEZGA-UHFFFAOYSA-N hypochlorite Chemical compound Cl[O-] WQYVRQLZKVEZGA-UHFFFAOYSA-N 0.000 description 4
- 241000196324 Embryophyta Species 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- PFUVRDFDKPNGAV-UHFFFAOYSA-N sodium peroxide Chemical compound [Na+].[Na+].[O-][O-] PFUVRDFDKPNGAV-UHFFFAOYSA-N 0.000 description 3
- 241001070947 Fagus Species 0.000 description 2
- 235000010099 Fagus sylvatica Nutrition 0.000 description 2
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000029087 digestion Effects 0.000 description 2
- OSVXSBDYLRYLIG-UHFFFAOYSA-N dioxidochlorine(.) Chemical compound O=Cl=O OSVXSBDYLRYLIG-UHFFFAOYSA-N 0.000 description 2
- 239000004744 fabric Substances 0.000 description 2
- 230000008929 regeneration Effects 0.000 description 2
- 238000011069 regeneration method Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000008399 tap water Substances 0.000 description 2
- 235000020679 tap water Nutrition 0.000 description 2
- 239000002023 wood Substances 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 239000004155 Chlorine dioxide Substances 0.000 description 1
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 1
- 229920002488 Hemicellulose Polymers 0.000 description 1
- QPCDCPDFJACHGM-UHFFFAOYSA-N N,N-bis{2-[bis(carboxymethyl)amino]ethyl}glycine Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(=O)O)CCN(CC(O)=O)CC(O)=O QPCDCPDFJACHGM-UHFFFAOYSA-N 0.000 description 1
- -1 Peroxide compounds Chemical class 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000000908 ammonium hydroxide Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000007844 bleaching agent Substances 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- LVGQIQHJMRUCRM-UHFFFAOYSA-L calcium bisulfite Chemical compound [Ca+2].OS([O-])=O.OS([O-])=O LVGQIQHJMRUCRM-UHFFFAOYSA-L 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 235000010260 calcium hydrogen sulphite Nutrition 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 150000001735 carboxylic acids Chemical class 0.000 description 1
- 235000019398 chlorine dioxide Nutrition 0.000 description 1
- MAYPHUUCLRDEAZ-UHFFFAOYSA-N chlorine peroxide Inorganic materials ClOOCl MAYPHUUCLRDEAZ-UHFFFAOYSA-N 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010411 cooking Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000011121 hardwood Substances 0.000 description 1
- 150000002432 hydroperoxides Chemical class 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 229910021432 inorganic complex Inorganic materials 0.000 description 1
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 1
- 235000019341 magnesium sulphate Nutrition 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- MGFYIUFZLHCRTH-UHFFFAOYSA-N nitrilotriacetic acid Chemical compound OC(=O)CN(CC(O)=O)CC(O)=O MGFYIUFZLHCRTH-UHFFFAOYSA-N 0.000 description 1
- 150000001451 organic peroxides Chemical class 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229960003330 pentetic acid Drugs 0.000 description 1
- 235000019353 potassium silicate Nutrition 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- CIHOLLKRGTVIJN-UHFFFAOYSA-N tert‐butyl hydroperoxide Chemical compound CC(C)(C)OO CIHOLLKRGTVIJN-UHFFFAOYSA-N 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
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
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1057—Multistage, with compounds cited in more than one sub-group D21C9/10, D21C9/12, D21C9/16
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Paper (AREA)
- Cosmetics (AREA)
Description
Fra norsk utlegningsskrift nr. 141317 er det kjent en fleretrinns fremgangsmåte til fullbleking av cellulose, som kan gjennomføres med vesentlig mindre kiormengder enn tidligere i de tilstedeværende tekniske innretninger i et celluloseblekeri. From Norwegian explanatory document no. 141317, a multi-stage method for complete bleaching of cellulose is known, which can be carried out with significantly smaller amounts of chlorine than previously in the existing technical devices in a cellulose bleaching plant.
Derved lar cellulosen seg fullbieke i flere trinn, fortrinnsvis trykkiøst, når biekesekvensen, eventuelt kombinert med en liten deiklorering, begynner med en sterk alkalisk per-oksydblekeoppslutning. Thereby, the cellulose can be fully bleached in several steps, preferably pressure-free, when the bleaching sequence, optionally combined with a small dechlorination, begins with a strong alkaline peroxide bleaching reaction.
Dette sterkt alkaliske peroksydbleketrinn (P) , teom samtidig også virker oppsluttende, erstatter den hittil vanlig sure klorering med etterfølgende alkalisk ekstraksjons-trinn. This strongly alkaline peroxide bleaching step (P), which at the same time also acts as an absorbent, replaces the usual acidic chlorination with a subsequent alkaline extraction step.
Blekeresultatet er herved - likeledes som ved The bleaching result is here - just like wood
de kjente blekefremgangsmåter - avhengig av tretypen, f.eks. the known bleaching methods - depending on the type of wood, e.g.
*iål- eller løvtre resp. enårsplanter, samt av gjennomføringen *eel or hardwood resp. annual plants, as well as of the implementation
av kokeprosessen og dermed oppslutningsgraden. of the cooking process and thus the degree of absorption.
Den eventuelle deiklorering er bare absolutt nødvendig når det skal blekes hårde, altså lignin- og hemi-celluloserike celluloser over hvithetsinnhold på 90% MgO. herved kan det enten før begynnelsen av den egentliae bleking, altså før det sterkt alkaliske peroksydtrinn foregå en deiklorering, eller det tilsluttes direkte til det sterkt alkaliske peroksydtrinn et delklorerings- og ekstraksjons-trinn. Derved brukes omtrent en femtedel av den tidligere klormengde og omtrent halvparten av den tidligere alkalimengde. Any dechlorination is only absolutely necessary when hard, i.e. lignin- and hemi-cellulose-rich celluloses above a whiteness content of 90% MgO are to be bleached. in this way, dechlorination can either take place before the start of the actual bleaching, i.e. before the strongly alkaline peroxide step, or a partial chlorination and extraction step can be connected directly to the strongly alkaline peroxide step. Thereby, approximately one fifth of the previous amount of chlorine and approximately half of the previous amount of alkali is used.
I en videreutvikling av fremgangsmåten ifølge norsk utlegningsskrift nr. 141317 er det nå overraskende funnet at ved overholdelse av bestemte reaksjonsbetingelser In a further development of the method according to Norwegian explanatory document no. 141317, it has now surprisingly been found that upon compliance with certain reaction conditions
ved peroksydtrinnet kan det innspares en betraktelig ytterligere alkalimengde. in the peroxide step, a considerably further amount of alkali can be saved.
Oppfinnelsens gjenstand er en fleretrinns fremgangsmåte til klorfattig fullbleking av cellulose, hvor blekesekvensene, eventuelt kombinert med en mindre deiklorering, begynner med en alkalisk peroksydoppløsning, fortrinnsvis trykkløs, og ved en temperatur av blekebadet på minst The object of the invention is a multi-stage process for chlorine-free complete bleaching of cellulose, where the bleaching sequences, possibly combined with a minor dechlorination, begin with an alkaline peroxide solution, preferably depressurized, and at a temperature of the bleaching bath of at least
65°C, idet fremgangsmåten er karakterisert ved at man bleker cellulosen i peroksydtrinnet ved et innhold av alkali fra 65°C, as the method is characterized by bleaching the cellulose in the peroxide step at a content of alkali from
0,5-2 vekt-%, beregnet på 100%-ig stoff og referert til atro (absolutt tørr) cellulose. 0.5-2% by weight, calculated on 100% material and referred to atro (absolutely dry) cellulose.
Ved fremgangsmåten ifølge oppfinnelsen blekes det fortrinnsvis med alkalimengder på 1-2 vekt-% beregnet i 100%-ig stoff referert til atro cellulose og ved temperaturer på 65-85°C. In the method according to the invention, bleaching is preferably done with alkali amounts of 1-2% by weight calculated in 100% material referred to atro cellulose and at temperatures of 65-85°C.
Den i kloreringstrinnet anvendte klormenade er bare en liten del av den menade som. kom til anvendelse ved de hittil kjente fremgangsmåter ved klorering. Peroksydtrinnet ut-føres med alkalioverskudd. Delkloreringstrinnet kan også unn-gås når de kjente oksydasjonsbleketrinn som følger oppslutnings-blekningen som hypoklorit, klordioksyd og peroksyd forsterkes. Selvsagt bortfaller delklorerinnen når det ikke kreves hvithetsinnhold over 90% MgO, men hvithetsinnhold mellom 85 og 90% MgO er tilstrekkelig. The chlorine menade used in the chlorination step is only a small part of the menade which. was used in the hitherto known methods of chlorination. The peroxide step is carried out with excess alkali. The partial chlorination step can also be avoided when the known oxidation bleaching steps that follow digestion bleaching such as hypochlorite, chlorine dioxide and peroxide are enhanced. Of course, partial chlorination is omitted when a whiteness content above 90% MgO is not required, but a whiteness content between 85 and 90% MgO is sufficient.
Blekingen med klor og alkali (C-E-trinn) bringer ved utløsing av organiske stoffer oksygenfortærende stoffer og sterkt klorholdige forbindelser i avvannet fra cellulose-fabrikker, som ikke mer kan tømmes i elver. Bleaching with chlorine and alkali (C-E stage) releases oxygen-consuming substances and strongly chlorine-containing compounds in the wastewater from cellulose factories, which can no longer be discharged into rivers.
Klorholdig og kloridioneholdig blekeriavvann fører som kjent til sterk korrosjon i regenerasjonsinnret^-ninger. Den omtalte alkaliske blekeoppslutning muliggjør inn-dampning og konsentrering av de utløste stoffer, deres forbren-ning og alkaliregenerering i vanlig apparatur. Den alkaliske peroksydbehandling har videre vist at 95-90% av de i avvannet belastende stoffer utløses i dette trinn og således ikke til-føres elvene. As is well known, chlorine-containing and chloride-ion-containing bleaching wastewater leads to strong corrosion in regeneration devices. The mentioned alkaline bleach digestion enables evaporation and concentration of the dissolved substances, their combustion and alkali regeneration in ordinary equipment. The alkaline peroxide treatment has also shown that 95-90% of the polluting substances in the wastewater are released in this step and are thus not supplied to the rivers.
Som peroksydforbindelser kommer det på tale hy-drogenperoksyd, natriumperoksyd og andre uorganiske eller organiske peroksyder resp. hydroperoksyder, fortrinnsvis hydro-genperoksyd, natriumperoksyd eller t-butylhydroperoksyd resp. blandinger av de nevnte komponenter i vandige oppløsninger. Helt spesielt egnet er hydroaenperoksyd og natriumperoksyd. De anvendte mengder kan ligge mellom 0,2 og 10 vekt-%, fortrinnsvis anvendes 0,6-6 vekt-%, beregnet som 100%-ig hydro-genperoksyd og referert til atro cellulose. Peroxide compounds include hydrogen peroxide, sodium peroxide and other inorganic or organic peroxides or hydroperoxides, preferably hydrogen peroxide, sodium peroxide or t-butyl hydroperoxide resp. mixtures of the aforementioned components in aqueous solutions. Hydrogen peroxide and sodium peroxide are particularly suitable. The quantities used can be between 0.2 and 10% by weight, preferably 0.6-6% by weight are used, calculated as 100% hydrogen peroxide and referred to atro cellulose.
De for den omtalte alkaliske, peroksydiske blekeoppslutning nødvendige alkalier, dvs. alkali- eller jordalkali-hydroksyder, er fortrinnsvis natriumhydroksyd eller ocrså kalsium-hydroksyd resp. ammoniumhydroksyd (NH^ eller NH^OH), nemlig mellom 0,5-3 vekt-%, fortrinnsvis 1-3 vek"t-%, beregnet som 100%-ig stoff og referert til atro cellulose. The alkalis required for the mentioned alkaline, peroxidic bleaching solution, i.e. alkali or alkaline earth hydroxides, are preferably sodium hydroxide or also calcium hydroxide or ammonium hydroxide (NH^ or NH^OH), namely between 0.5-3% by weight, preferably 1-3% by weight, calculated as 100% substance and referred to atro cellulose.
Den alkalisk-peroksydiske blekeoppslutnina gjen-nomføres på kjent måte ved temperaturer fra 65°C til blekebadets kokepunkt. I og for seg kan det selvsagt blekes under trykk, men fordelen ved anvendelse av perforbindelser og den nevnte sekvens ligger nettopp i fremgangsmåtens trykkløshet, dvs. uten anvendelse av ekstra trykk og apparatur. The alkaline-peroxide bleaching process is carried out in a known manner at temperatures from 65°C to the boiling point of the bleaching bath. In and of itself, it can of course be bleached under pressure, but the advantage of using percompounds and the mentioned sequence lies precisely in the pressurelessness of the process, i.e. without the use of additional pressure and equipment.
Blekefremgangsmåten gjennomføres som nevnt oven-for i bestående blekerier, idet det fortrinnsvis er vanlig stofftettheter mellom 10 og 20%.. Med stofftetthet forstås The bleaching process is carried out as mentioned above in existing bleachers, with fabric densities of between 10 and 20% being preferred.
da vekt-% cellulose i stoffsuspensjonen. Det er imidlertid then weight-% cellulose in the fabric suspension. However, it is
også mulig å gjennomføre det alkalisk peroksydiske trinn ved høyere tørrinnhold, nemlig under anvendelse av<i.dertil egnéde tekniske hjelpemidler inntil 35%, som f.eks. tykkstoffpumper, knaere, høytrykkfiltere. also possible to carry out the alkaline peroxide step at a higher dry content, namely using suitable technical aids up to 35%, such as e.g. thickener pumps, kneaders, high-pressure filters.
En ytterligere fordel er at det ikke kommer til A further advantage is that it does not have to
o o
anvendelse noe vannglass som ellers ved peroksydiske bleke-trinn. use some water glass as otherwise with peroxidic bleaching steps.
I blekebadene kan det anvendes vanlige uorganiske kompleksdannere resp. stabilisatorer, som f.eks. magne-siumsulfat eller organiske N- eller P-hoidige kompleksdannere, som f.eks. etylendiamintetraeddiksyre, dietylentriaminpenta-eddiksyre, nitrilotrieddiksyre. Det er likeledes mulig å anvende N- og P-frie kompleksdannere, som f.eks. polyoksy-4 karboksyl syrer. In the bleaching baths, common inorganic complex formers or stabilizers, such as magnesium sulfate or organic N- or P-containing complex formers, such as e.g. ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, nitrilotriacetic acid. It is also possible to use N- and P-free complex formers, such as e.g. polyoxy-4 carboxylic acids.
I tillegg til det tekniske fremskritt ifølge utlegningsskrift nr. 141317, nemlig en fullbleking av cellulose, også av harde celluloser, i bestående apparaturer i celluloseblekerier, samt utvinning av avvann, hvor stoffene som belaster elvene allerede er fjernet i første trinn, således at det fremkommer korrosjonsfritt avvann som lett kan regenereres - medfører fremgangsmåten ifølge oppfinnelsen In addition to the technical progress according to interpretation document no. 141317, namely a full bleaching of cellulose, also of hard celluloses, in existing equipment in cellulose bleaching plants, as well as extraction of waste water, where the substances that burden the rivers have already been removed in the first stage, so that it appears corrosion-free waste water that can be easily regenerated - entails the method according to the invention
en ytterligere besparelse på alkali. a further saving on alkali.
Følgende eksempel skal forklare oppfinnelsen nærmere, hvor prosentangivelsene alltid er å forstå som vekt-%, referert til ubleket tørr cellulose. Ved forsøket ble det ar-beidet med springvann av 5° dH i emaljerte beholdere oa etter hvert trinn vaskes cellulosen med springvann samt surgjøres etter siste trinn med SC^. Den angitte hvithetsgrad (remisjons-grad) bestemmes etter de tyske enhetsmetoder (Zellcheming-Merk-blad) med Zeiss-Elrepho-hvithetsgradsmåler, filter R 46. The following example will explain the invention in more detail, where the percentages are always to be understood as % by weight, referring to unbleached dry cellulose. In the experiment, the work was done with tap water of 5° dH in enamelled containers and after each step the cellulose is washed with tap water and acidified after the last step with SC^. The stated degree of whiteness (degree of remission) is determined according to the German unit methods (Zellcheming-Merk sheet) with a Zeiss-Elrepho whiteness degree meter, filter R 46.
Eksempel Example
En etter kalsium-bisulfitfremgangsmåten frem-stilt bøkepapircellulose, med et kappatall på 14 og et hvithetsinnhold på 53% MgO ubleket, ble bleket i driftsmessig måle-stokk i en 4-trinnet fremgangsmåte til en slutthvithet på 95-96% MgO. A beech paper cellulose produced by the calcium-bisulphite process, with a kappa number of 14 and a whiteness content of 53% MgO unbleached, was bleached on an operational scale in a 4-stage process to a final whiteness of 95-96% MgO.
Fasthetsegenskapene av den etter denne sekvens blekede bøke-papircellulose lå. høyere enn de i vanlig bedrifts-bleking oppnådde verdier. Dette er å tilbakeføre på at det blir sett bort fra hypoklorittrinnet. Dessuten medfører selvsagt den 4-trinns fremgangsmåte en økonomisk fordel i forhold til den klassiske 5-trinnsbleking. The firmness properties of the beech paper cellulose bleached after this sequence were higher than the values obtained in normal commercial bleaching. This is due to the fact that the hypochlorite step is disregarded. In addition, of course, the 4-stage method entails an economic advantage compared to the classic 5-stage bleaching.
Claims (2)
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2538673A DE2538673C2 (en) | 1975-08-30 | 1975-08-30 | Bleaching of cellulose with considerably reduced use of chlorine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| NO754077L NO754077L (en) | 1977-03-01 |
| NO145344B true NO145344B (en) | 1981-11-23 |
Family
ID=5955230
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| NO754077A NO145344B (en) | 1975-08-30 | 1975-12-03 | MULTIPLE-STEP PROCEDURE FOR CHLOROUS WHITENING OF CELLULOSE |
Country Status (17)
| Country | Link |
|---|---|
| AR (1) | AR221678A1 (en) |
| AT (1) | AT340765B (en) |
| BE (1) | BE836462R (en) |
| BR (1) | BR7603006A (en) |
| CA (1) | CA1080406A (en) |
| CH (1) | CH620002A5 (en) |
| DE (1) | DE2538673C2 (en) |
| ES (1) | ES443318A1 (en) |
| FI (1) | FI62869C (en) |
| FR (1) | FR2322235A1 (en) |
| GB (1) | GB1544216A (en) |
| IT (1) | IT1055792B (en) |
| NL (1) | NL7513942A (en) |
| NO (1) | NO145344B (en) |
| SE (1) | SE7602842L (en) |
| YU (1) | YU37370B (en) |
| ZA (1) | ZA757822B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2416297A1 (en) * | 1978-01-31 | 1979-08-31 | Europeen Cellulose | Three-stage paper pulp bleaching - giving high whiteness level, by treating with chlorine, hypochlorite or peroxide oxidant and chlorine di:oxide |
| FR2432574A1 (en) * | 1978-08-01 | 1980-02-29 | Europeen Cellulose | PROCESS FOR BLEACHING PAPER PULP |
| FR2572431B1 (en) * | 1984-10-25 | 1987-12-04 | Centre Tech Ind Papier | PROCESS FOR THE PREPARATION OF CHEMICAL PAPER PULP FOR BLEACHING. |
| EP0402335B2 (en) * | 1989-06-06 | 2001-03-14 | Eka Chemicals AB | Process for bleaching lignocellulose-containing pulps |
| SE9001481L (en) * | 1990-04-23 | 1991-10-24 | Eka Nobel Ab | REDUCTION OF HALOGEN ORGANIC SUBSTANCES IN BLEACHING WASTE |
| SE466061B (en) * | 1990-04-23 | 1991-12-09 | Eka Nobel Ab | Bleaching of chemical pulp by treatment with first a complexing agent and then a peroxide containing substance |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE753531C (en) * | 1938-11-09 | 1953-05-18 | Degussa | Process for bleaching pulp |
| DE2327900C3 (en) * | 1973-06-01 | 1985-02-07 | Degussa Ag, 6000 Frankfurt | Bleaching of cellulose with considerably reduced use of chlorine |
-
1975
- 1975-08-30 DE DE2538673A patent/DE2538673C2/en not_active Expired
- 1975-11-12 AT AT861075A patent/AT340765B/en not_active IP Right Cessation
- 1975-11-25 FI FI753314A patent/FI62869C/en not_active IP Right Cessation
- 1975-11-28 NL NL7513942A patent/NL7513942A/en not_active Application Discontinuation
- 1975-11-28 YU YU3012/75A patent/YU37370B/en unknown
- 1975-12-03 NO NO754077A patent/NO145344B/en unknown
- 1975-12-09 BE BE6045289A patent/BE836462R/en not_active IP Right Cessation
- 1975-12-09 ES ES443318A patent/ES443318A1/en not_active Expired
- 1975-12-15 ZA ZA757822A patent/ZA757822B/en unknown
-
1976
- 1976-01-05 AR AR261846A patent/AR221678A1/en active
- 1976-01-14 IT IT67078/76A patent/IT1055792B/en active
- 1976-02-05 CA CA245,088A patent/CA1080406A/en not_active Expired
- 1976-02-25 FR FR7605307A patent/FR2322235A1/en active Granted
- 1976-02-27 SE SE7602842A patent/SE7602842L/en unknown
- 1976-04-22 GB GB16311/76A patent/GB1544216A/en not_active Expired
- 1976-05-13 BR BR7603006A patent/BR7603006A/en unknown
- 1976-08-26 CH CH1084076A patent/CH620002A5/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| BR7603006A (en) | 1977-05-31 |
| NL7513942A (en) | 1977-03-02 |
| ZA757822B (en) | 1976-11-24 |
| ES443318A1 (en) | 1977-05-01 |
| ATA861075A (en) | 1977-04-15 |
| BE836462R (en) | 1976-06-09 |
| FI753314A (en) | 1977-03-01 |
| YU301275A (en) | 1983-04-27 |
| FR2322235B1 (en) | 1979-04-06 |
| GB1544216A (en) | 1979-04-19 |
| FI62869C (en) | 1983-03-10 |
| CH620002A5 (en) | 1980-10-31 |
| FR2322235A1 (en) | 1977-03-25 |
| FI62869B (en) | 1982-11-30 |
| CA1080406A (en) | 1980-07-01 |
| AT340765B (en) | 1978-01-10 |
| NO754077L (en) | 1977-03-01 |
| YU37370B (en) | 1984-08-31 |
| DE2538673C2 (en) | 1986-01-16 |
| DE2538673A1 (en) | 1977-03-03 |
| SE7602842L (en) | 1977-03-01 |
| IT1055792B (en) | 1982-01-11 |
| AR221678A1 (en) | 1981-03-13 |
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