CA2372069C - Process for bleaching chemical pulps with low organic halogen compounds content - Google Patents
Process for bleaching chemical pulps with low organic halogen compounds content Download PDFInfo
- Publication number
- CA2372069C CA2372069C CA2372069A CA2372069A CA2372069C CA 2372069 C CA2372069 C CA 2372069C CA 2372069 A CA2372069 A CA 2372069A CA 2372069 A CA2372069 A CA 2372069A CA 2372069 C CA2372069 C CA 2372069C
- Authority
- CA
- Canada
- Prior art keywords
- bleaching
- organic halogen
- halogen compounds
- pulp
- chemical pulps
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
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
- D21C9/12—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds
- D21C9/14—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds with ClO2 or chlorites
- D21C9/144—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds with ClO2 or chlorites with ClO2/Cl2 and other bleaching agents in a multistage process
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1026—Other features in bleaching processes
- D21C9/1042—Use of chelating agents
-
- 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
-
- 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
- D21C9/147—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications
-
- 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
- D21C9/16—Bleaching ; Apparatus therefor with per compounds
- D21C9/163—Bleaching ; Apparatus therefor with per compounds with peroxides
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Paper (AREA)
Abstract
The present invention refers to a process for bleaching chemical pulps comprising a step of adding chlorine dioxide in a pH in the range of about 4.5 to 5.5 as the first bleaching stage. The process of the present invention provides for obtaining contents of organic halogen compounds in the final pulp product lower than 30 ppm and for a reduction in the H2O2 needed for the subsequent stages.
Description
PROCESS FOR BLEACHING CHEMICAL PULPS WITH LOW ORGANIC HALOGEN COMPOUNDS
CONTENT
Field of the Invention The present invention refers to an enhanced process for bleaching pulps that al-lows the obtention of a low concentration of organic halogen compounds in the final cellu-lose pulp .
Background of the Invention In view of increasing market demands, several studies have been carried out in an attempt to obtain pulps with properties similar to those known as TCF
(total chlorine free), but that can reduce production costs. Several alternatives have been proposed for proc-esses that yield pulps with good brightness properties without causing environment contami-nation and with low amounts of organic halogen compounds expressed by a low OX
con-tent ("organically bound halogen").
The decrease in the halogen compounds organically bound to the pulp have al-ready been studied by Suss et al (Suss, Hans U., at at., 1991, TAPPI Pulping Conference, 705-71). This paper discloses the results achieved in the reduction of OX
content in the pulp through a step of weak alkaline extraction in the presence of H202 carried out in the end of the bleaching process. On the other hand, Annergen et al (1990, TAPPI Pulping Conference, 185-194) teach that the removal of halogen compounds organically bound to the pulp is very difficult and that it would only be possible by the addition of an alkali due to their high mo-lecular weight. That study also mentions that a partial removal of said compounds may occur by combining steps of severe washing and controlled chlorinating the pulp.
Another study about the removal of organic chlorine compounds from chemical pulps was disclosed by Gunnarsson et al (1996, JPPS. J457-J463) who described the mechanism of OX and AOX formation in the pulp and concluded that it would be possible to reduce the OCI levels in the pulp by working with a final pH value around 4 in the deoxidizing step and that variation in the amount of chlorine dioxide added in this phase would not yield an increasing concentration of OCI in the final pulp product.
Further processes have also been proposed with the objective of reducing the organic halogen compounds during the treatment of chemical pulps by using chlorine diox-ide. An example of such processes is presented in patent EP 500,813 that discloses a proc-ess for bleaching ligno-cellulosic pulps with reduced formation of organic halogen com-pounds carried out by adding C102 in a first bleaching step, followed by a second step com-prising the treatment of the pulp with hydrogen peroxide and at least one further step of treatment with chlorine dioxide.
Another example of a process for reducing the content of organic halogen com-pounds in chemical pulps in which chlorine dioxide is added is taught in US
5,030,324. Ac-cording to that process several steps comprising chlorine treatment are carried out, including a step wherein chlorine dioxide is necessarily added together with separate additions of chlo-rine, wherein the stage of C102 treatment is effected at low pulp consistency.
Patent US 4,959,124 refers to a process for reducing organic halogen com-pounds in low consistency pulp by treating the pulp with chlorine dioxide in a first bleaching step necessarily followed by a stage of ozone treatment.
However, it was still desirable to develop a process for bleaching chemical pulps that could provide the removal of the organic halogen compounds in a more effective man-ner and with significant reduction of production costs.
The objective of the present invention is, therefore, to provide a pulp bleaching process that allows an efficient reduction the OX content specially in low consistency pulps, and that can also reduce the amount of chemicals necessary to achieve the final OX reduc-tion.
Summary of the Invention The present invention refers to a process for bleaching low consistency chemical pulps comprising a step of adding chlorine dioxide in a pH in the range of about 4.5 to 5.5 as the first bleaching stage.
CONTENT
Field of the Invention The present invention refers to an enhanced process for bleaching pulps that al-lows the obtention of a low concentration of organic halogen compounds in the final cellu-lose pulp .
Background of the Invention In view of increasing market demands, several studies have been carried out in an attempt to obtain pulps with properties similar to those known as TCF
(total chlorine free), but that can reduce production costs. Several alternatives have been proposed for proc-esses that yield pulps with good brightness properties without causing environment contami-nation and with low amounts of organic halogen compounds expressed by a low OX
con-tent ("organically bound halogen").
The decrease in the halogen compounds organically bound to the pulp have al-ready been studied by Suss et al (Suss, Hans U., at at., 1991, TAPPI Pulping Conference, 705-71). This paper discloses the results achieved in the reduction of OX
content in the pulp through a step of weak alkaline extraction in the presence of H202 carried out in the end of the bleaching process. On the other hand, Annergen et al (1990, TAPPI Pulping Conference, 185-194) teach that the removal of halogen compounds organically bound to the pulp is very difficult and that it would only be possible by the addition of an alkali due to their high mo-lecular weight. That study also mentions that a partial removal of said compounds may occur by combining steps of severe washing and controlled chlorinating the pulp.
Another study about the removal of organic chlorine compounds from chemical pulps was disclosed by Gunnarsson et al (1996, JPPS. J457-J463) who described the mechanism of OX and AOX formation in the pulp and concluded that it would be possible to reduce the OCI levels in the pulp by working with a final pH value around 4 in the deoxidizing step and that variation in the amount of chlorine dioxide added in this phase would not yield an increasing concentration of OCI in the final pulp product.
Further processes have also been proposed with the objective of reducing the organic halogen compounds during the treatment of chemical pulps by using chlorine diox-ide. An example of such processes is presented in patent EP 500,813 that discloses a proc-ess for bleaching ligno-cellulosic pulps with reduced formation of organic halogen com-pounds carried out by adding C102 in a first bleaching step, followed by a second step com-prising the treatment of the pulp with hydrogen peroxide and at least one further step of treatment with chlorine dioxide.
Another example of a process for reducing the content of organic halogen com-pounds in chemical pulps in which chlorine dioxide is added is taught in US
5,030,324. Ac-cording to that process several steps comprising chlorine treatment are carried out, including a step wherein chlorine dioxide is necessarily added together with separate additions of chlo-rine, wherein the stage of C102 treatment is effected at low pulp consistency.
Patent US 4,959,124 refers to a process for reducing organic halogen com-pounds in low consistency pulp by treating the pulp with chlorine dioxide in a first bleaching step necessarily followed by a stage of ozone treatment.
However, it was still desirable to develop a process for bleaching chemical pulps that could provide the removal of the organic halogen compounds in a more effective man-ner and with significant reduction of production costs.
The objective of the present invention is, therefore, to provide a pulp bleaching process that allows an efficient reduction the OX content specially in low consistency pulps, and that can also reduce the amount of chemicals necessary to achieve the final OX reduc-tion.
Summary of the Invention The present invention refers to a process for bleaching low consistency chemical pulps comprising a step of adding chlorine dioxide in a pH in the range of about 4.5 to 5.5 as the first bleaching stage.
Brief Description of the Drawings Figures 1 and 2 are graphics that respectively demonstrate the total amount of peroxide added to the pulp produced in accordance with the present invention and the amount of peroxide relative to the initial Kappa number.
Figure 3 illustrates the average concentration OX concentration in pulps treated in accordance with the present invention when compared to pulps treated by methods com-prising different bleaching parameters.
Figure 4 shows the brightness increase obtained with the addition of C102 in the Do stage.
Figure 5 presents a graphic that illustrates the relationship between the amount of chlorine dioxide added to the pulp and the OX concentration in the final product.
Figure 6 shows a graphic that illustrates the relationship of the pH value in the first bleaching step with the organic halogen compounds content.
Figures 7 and 8 are graphics that illustrate the OX profile in two different proccess conditions.
Detailed Description of the Invention After several studies the present inventors found out that excellent results in the reduction of organic halogen compounds may be achieved in a process for bleaching previ-ously delignified low consistency chemical pulps when a step of adding chlorine dioxide is carried out as the first bleaching stage, said addition of chlorine dioxide being effected in a pH range of about 4.5 to 5.5.
Contrary to the teachings of the processes known from the prior art according to which a reduction of pH values would lead to a substantial increase of OX
formation, it has now been found that the use of an acid during the chlorine dioxide step (Do) in order to provide a pH values in the range of about 4.5 to 5.5 decreases the concentration of organic halogen compounds. Although it was already recognized that a better efficiency in the use of C102 could be obtained at low pH values, the consequent high formation of OX was always considered as a significant technical drawback in this kind of process, which drawback has now been overcome by the process of the present invention by establishing the optimum values of pH.
Figure 3 illustrates the average concentration OX concentration in pulps treated in accordance with the present invention when compared to pulps treated by methods com-prising different bleaching parameters.
Figure 4 shows the brightness increase obtained with the addition of C102 in the Do stage.
Figure 5 presents a graphic that illustrates the relationship between the amount of chlorine dioxide added to the pulp and the OX concentration in the final product.
Figure 6 shows a graphic that illustrates the relationship of the pH value in the first bleaching step with the organic halogen compounds content.
Figures 7 and 8 are graphics that illustrate the OX profile in two different proccess conditions.
Detailed Description of the Invention After several studies the present inventors found out that excellent results in the reduction of organic halogen compounds may be achieved in a process for bleaching previ-ously delignified low consistency chemical pulps when a step of adding chlorine dioxide is carried out as the first bleaching stage, said addition of chlorine dioxide being effected in a pH range of about 4.5 to 5.5.
Contrary to the teachings of the processes known from the prior art according to which a reduction of pH values would lead to a substantial increase of OX
formation, it has now been found that the use of an acid during the chlorine dioxide step (Do) in order to provide a pH values in the range of about 4.5 to 5.5 decreases the concentration of organic halogen compounds. Although it was already recognized that a better efficiency in the use of C102 could be obtained at low pH values, the consequent high formation of OX was always considered as a significant technical drawback in this kind of process, which drawback has now been overcome by the process of the present invention by establishing the optimum values of pH.
The addition of C102 in the first bleaching stage together with the control of the pH in the range of 4.5 to 5.5 allows the use of CIO2 charges up to 10 kg/tsa without any dis-advantageous production of organic halogen compounds. In a preferred embodiment of the invention, the CIO2 is added to the pulp in a range of 6 kg/tsa to 8 kg/tsa, more preferable at about 8 kg/tsa.
According to the process of the present invention it is possible to obtain organic halogen compounds concentrations in the final product (pulp) lower than about 30 ppm.
Such a low OX formation is primarily due to the enhanced control of the pH
during the de-oxidation step followed by the conventional subsequent extraction steps based on the use of sodium hydroxide and hydrogen peroxide. Thus, in a bleaching stage comprising, for exam-ple, the sequential steps Do-Eop-Q-(Po-P), that is, treatment steps with (chlorine dioxide -hydrogen peroxide alkali - sequestering agents (chelating agents) - peroxide ozone perox-ide), expressive gains in brightness and in the reduction of chemicals necessary to the re-moval of organic halogen compounds are obtained by working at low consistency conditions and with addition of chlorine dioxide in the first bleaching stage, and further controlling the pH in the ideal range of 4.5 to 5.5.
The graphic shown in Figure 3 indicates a more efficient control of the average OX content in the resulting product in accordance with the present invention, with said OX
values being stable at levels of about 15 ppm. As can be concluded by comparing these values with those of pulps obtained by conventional processes, when the deoxidation step is not carried out under conditions in accordance with the present invention, it is sometimes possible to reach low OX contents but which are not stable.
Analysis of the obtained results showed that the process according to the inven-tion decreases the need of H2O2 addition during the bleaching stage, which represents a significant technical and economic advantage never achieved by the prior art processes.
Figure 1 illustrates the decrease of H202 added to the pulp in a process according to the invention, wherein the gain in the reduction of the H202 employed may be of up 40% while maintaining the low content of OX and low brightness reversion. H2O2 reductions to values lower than 35 kg/tsa were achieved. On the other hand, Figure 2 shows the relationship between the peroxide added and the initial Kappa number which is also a good indicative of the reduction of the H202 needed and, consequently, of the enhanced results in the final product.
Therefore, the addition of C102 in the first stage of the bleaching process carried out under the above mentioned conditions helps the removal of the organic charge, also contributing for the removal of lignin, as well as the increase of the H202 reactivity in the Eop stage, whereby providing enhanced brightness when compared to pulps treated with the same amount of peroxide within conventional processes. The pulps obtained by the process according to the present invention show brightness of about 90% ISO and all technical proc-ess parameters lead to low production costs and to a high recycling rates of effluents in the bleaching process.
Figure 5 presents the relationship of the added chlorine dioxide amount to the OX content formed in the pulp during the process of the invention. It can be seen that the ratio of CIO2 to the OX content did not vary even when increasing the C102 amount, which indicates that the latter acted for removing the OX present in the pulp after the first stage, thus maintaining the pulp quality in the desirable levels.
Figure 4 shows the potential brightness gain with the addition of C102 in a stage prior to the step of adding hydrogen peroxide. The performance of the Eop stage was sub-stantially enhanced with the addition of 2 Kg/tsa of C102 in the Do.
In order to obtain the desired brightness levels in the Eop stage without nega-tively affecting the OX results, an optimum range for the pH was determined for the Do stage and, therefore, an ideal application range was established as indicated in Figure 6.
After some experiments, it was observed that an addition of CIO2 in the first stage also provided an increasing in the number of washing/extraction stages, substantially decreasing the amount of OX present in the pulp. Moreover, Figures 7 and 8 show that the Eop stage has the best performance in the removal of the organic halogen compounds while stages such as PO (pressurized peroxide) do not present good capacity for removing said OX.
According to the process of the present invention it is possible to obtain organic halogen compounds concentrations in the final product (pulp) lower than about 30 ppm.
Such a low OX formation is primarily due to the enhanced control of the pH
during the de-oxidation step followed by the conventional subsequent extraction steps based on the use of sodium hydroxide and hydrogen peroxide. Thus, in a bleaching stage comprising, for exam-ple, the sequential steps Do-Eop-Q-(Po-P), that is, treatment steps with (chlorine dioxide -hydrogen peroxide alkali - sequestering agents (chelating agents) - peroxide ozone perox-ide), expressive gains in brightness and in the reduction of chemicals necessary to the re-moval of organic halogen compounds are obtained by working at low consistency conditions and with addition of chlorine dioxide in the first bleaching stage, and further controlling the pH in the ideal range of 4.5 to 5.5.
The graphic shown in Figure 3 indicates a more efficient control of the average OX content in the resulting product in accordance with the present invention, with said OX
values being stable at levels of about 15 ppm. As can be concluded by comparing these values with those of pulps obtained by conventional processes, when the deoxidation step is not carried out under conditions in accordance with the present invention, it is sometimes possible to reach low OX contents but which are not stable.
Analysis of the obtained results showed that the process according to the inven-tion decreases the need of H2O2 addition during the bleaching stage, which represents a significant technical and economic advantage never achieved by the prior art processes.
Figure 1 illustrates the decrease of H202 added to the pulp in a process according to the invention, wherein the gain in the reduction of the H202 employed may be of up 40% while maintaining the low content of OX and low brightness reversion. H2O2 reductions to values lower than 35 kg/tsa were achieved. On the other hand, Figure 2 shows the relationship between the peroxide added and the initial Kappa number which is also a good indicative of the reduction of the H202 needed and, consequently, of the enhanced results in the final product.
Therefore, the addition of C102 in the first stage of the bleaching process carried out under the above mentioned conditions helps the removal of the organic charge, also contributing for the removal of lignin, as well as the increase of the H202 reactivity in the Eop stage, whereby providing enhanced brightness when compared to pulps treated with the same amount of peroxide within conventional processes. The pulps obtained by the process according to the present invention show brightness of about 90% ISO and all technical proc-ess parameters lead to low production costs and to a high recycling rates of effluents in the bleaching process.
Figure 5 presents the relationship of the added chlorine dioxide amount to the OX content formed in the pulp during the process of the invention. It can be seen that the ratio of CIO2 to the OX content did not vary even when increasing the C102 amount, which indicates that the latter acted for removing the OX present in the pulp after the first stage, thus maintaining the pulp quality in the desirable levels.
Figure 4 shows the potential brightness gain with the addition of C102 in a stage prior to the step of adding hydrogen peroxide. The performance of the Eop stage was sub-stantially enhanced with the addition of 2 Kg/tsa of C102 in the Do.
In order to obtain the desired brightness levels in the Eop stage without nega-tively affecting the OX results, an optimum range for the pH was determined for the Do stage and, therefore, an ideal application range was established as indicated in Figure 6.
After some experiments, it was observed that an addition of CIO2 in the first stage also provided an increasing in the number of washing/extraction stages, substantially decreasing the amount of OX present in the pulp. Moreover, Figures 7 and 8 show that the Eop stage has the best performance in the removal of the organic halogen compounds while stages such as PO (pressurized peroxide) do not present good capacity for removing said OX.
Claims (2)
1. A process for bleaching low consistency chemical pulps char-acterized by comprising the sequential steps Do-Eop-Q-(Po-P) wherein the addition of chlorine dioxide is carried out only in the first bleaching stage as a charge of 6 Kg/adt to 8 Kg/adt and at a pH in the range of 4.5 to 5.5.
2. Process according to claim 1, characterized in that the chlo-rine dioxide is added as a charge of 8 Kg/adt.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| BR9901291A BR9901291B1 (en) | 1999-04-27 | 1999-04-27 | process for bleaching low consistency chemical pulps. |
| BRPI9901291-0 | 1999-04-27 | ||
| PCT/BR2000/000038 WO2000065148A1 (en) | 1999-04-27 | 2000-04-27 | Process for bleaching chemical pulps with low organic halogen compounds content |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2372069A1 CA2372069A1 (en) | 2000-11-02 |
| CA2372069C true CA2372069C (en) | 2011-06-21 |
Family
ID=4072226
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2372069A Expired - Lifetime CA2372069C (en) | 1999-04-27 | 2000-04-27 | Process for bleaching chemical pulps with low organic halogen compounds content |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP1180172B1 (en) |
| BR (1) | BR9901291B1 (en) |
| CA (1) | CA2372069C (en) |
| ES (1) | ES2501141T3 (en) |
| IS (1) | IS6132A (en) |
| NO (1) | NO331632B1 (en) |
| PT (1) | PT1180172E (en) |
| WO (1) | WO2000065148A1 (en) |
| ZA (1) | ZA200108811B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002099186A1 (en) * | 2001-06-06 | 2002-12-12 | Kvaerner Pulping Ab | Reduction of organically bound chlorine formed in chlorine dioxide bleaching |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3720577A (en) * | 1970-05-25 | 1973-03-13 | Int Paper Co | Chlorine dioxide-peracetic acid-chlorine dioxide pulp bleaching sequence |
| SU1141128A1 (en) * | 1983-12-08 | 1985-02-23 | Центральный научно-исследовательский институт бумаги | Pulp bleaching process |
| US4959124A (en) | 1989-05-05 | 1990-09-25 | International Paper Company | Method of bleaching kraft pulp in a DZED sequence |
| DE69026105T2 (en) * | 1989-10-19 | 1996-09-26 | Univ North Carolina | HIGH-PERFORMANCE METHOD FOR BLEACHING CELLULAR WITH CHLORDIOXYD |
| US5030324A (en) | 1990-01-29 | 1991-07-09 | Champion International Corporation | Sequential bleaching procedure using chlorine and chlorine dioxide in a first chlorination stage of a multistage bleaching process |
| SE9000340L (en) | 1990-01-31 | 1991-08-01 | Eka Nobel Ab | PROCEDURES FOR BLACKING OF LIGNOCELLULOSALLY MATERIAL |
-
1999
- 1999-04-27 BR BR9901291A patent/BR9901291B1/en not_active IP Right Cessation
-
2000
- 2000-04-27 EP EP00926590.1A patent/EP1180172B1/en not_active Expired - Lifetime
- 2000-04-27 WO PCT/BR2000/000038 patent/WO2000065148A1/en not_active Ceased
- 2000-04-27 CA CA2372069A patent/CA2372069C/en not_active Expired - Lifetime
- 2000-04-27 PT PT926590T patent/PT1180172E/en unknown
- 2000-04-27 ES ES00926590.1T patent/ES2501141T3/en not_active Expired - Lifetime
-
2001
- 2001-10-25 ZA ZA200108811A patent/ZA200108811B/en unknown
- 2001-10-26 IS IS6132A patent/IS6132A/en unknown
- 2001-10-26 NO NO20015241A patent/NO331632B1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| BR9901291B1 (en) | 2011-11-01 |
| WO2000065148A1 (en) | 2000-11-02 |
| EP1180172A1 (en) | 2002-02-20 |
| NO20015241L (en) | 2001-11-27 |
| NO331632B1 (en) | 2012-02-13 |
| BR9901291A (en) | 2000-11-07 |
| PT1180172E (en) | 2014-09-25 |
| NO20015241D0 (en) | 2001-10-26 |
| ES2501141T3 (en) | 2014-10-01 |
| ZA200108811B (en) | 2002-10-25 |
| CA2372069A1 (en) | 2000-11-02 |
| IS6132A (en) | 2001-10-26 |
| EP1180172B1 (en) | 2014-07-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |
Effective date: 20200427 |