CA2374673A1 - Method to improve the opacity of mechanical pulp by using aliphatic peroxyacids and use of peroxyacids to improve opacity - Google Patents
Method to improve the opacity of mechanical pulp by using aliphatic peroxyacids and use of peroxyacids to improve opacity Download PDFInfo
- Publication number
- CA2374673A1 CA2374673A1 CA002374673A CA2374673A CA2374673A1 CA 2374673 A1 CA2374673 A1 CA 2374673A1 CA 002374673 A CA002374673 A CA 002374673A CA 2374673 A CA2374673 A CA 2374673A CA 2374673 A1 CA2374673 A1 CA 2374673A1
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- Prior art keywords
- pulp
- opacity
- acid
- bleaching
- aliphatic
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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
- D21C9/16—Bleaching ; Apparatus therefor with per compounds
- D21C9/166—Bleaching ; Apparatus therefor with per compounds with peracids
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
- D21H11/16—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only modified by a particular after-treatment
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Paper (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
Abstract
The invention relates to a method for treating mechanical pulp so that aliphatic percarboxylic acid in the amount of 0.5 - 5 kg/ton of pulp is adde d to the pulp to improve the opacity.
Description
Me#~hc~ f~~ ~n~azowe the onac ity of mer~hani_ca3 pulp by using aliphatic peroxyacids and use of peroxyacids to prove opacity.
The invention relates to a process for treating mechanical pulps, which can be used to affect the opacity of the pulp.
The nontransparent aspect of paper is described by opacity, which, along with brightness, is an important property of pulp in paper manufacture. Almost invaria-bly, however, the opacity of the pulp decreases when the brightness increases.
At present, mechanical pulps (refiner mechanical pulp, groundwood pulp, and chemi-mechanical pulp) are more and more often bleached with hydrogen peroxide. Di-thionite bleaching is also used either alone or together with peroxide bleaching, whereupon dithionite is either used as refiner bleaching or after-bleaching.
In the peroxide bleaching of pulp, mechanical pulp in particular, the decrease of opacity is clearly detectable, while the dithionite bleaching does not necessarily decrease the opacity. Generally, the lighter the level of bleaching the pulp, the lower the opacity of the pulp. The appended Fig. 1 that shows a variation in the opacity of spruce TMP, when peroxide is used to bleach pulp to various degrees of brightness mani-fests this. In certain paper grades, opacity is an important property. If we want to advance peroxide bleaching at the expense of dithionite bleaching, it would be im-portant to be able to optimize peroxide bleaching so that the opacity remains as high as possible while the brightness grows.
Generally, the chemicals used in the peroxide bleaching of mechanical pulps are hydrogen peroxide, lye (alkali), and waterglass. The purpose of the base is to in-crease the pH to a sufficiently high level, so that the hydrogen peroxide is dissoci-ated producing perhydroxyl anions. The purpose of the waterglass is to stabilize the hydrogen peroxide bleaching.
It is well known that peracetic acid can be produced in situ, for example, from acetanhydride or TAED (tetra acetyl ethylene diamine) or some other corresponding activator. One disadvantage of TAED is its high price and that it is a solid sub-stance. It would be necessary to disperse the TAED in water before adding it to the pulp, which makes it difficult to use. Furthermore, TAED contains nitrogen, which might constitute a problem for environmental protection. Acetanhydride is rela-tively cheap, but it would cause odour nuisance and be an inconvenient substance from the point of view of industrial safety. In addition, when fed into an alkaline 3 5 bleaching solution (NaOH + H202 + waterglass), it would readily cause silicate pre-cipitate and consume the lye.
The invention relates to a process for treating mechanical pulps, which can be used to affect the opacity of the pulp.
The nontransparent aspect of paper is described by opacity, which, along with brightness, is an important property of pulp in paper manufacture. Almost invaria-bly, however, the opacity of the pulp decreases when the brightness increases.
At present, mechanical pulps (refiner mechanical pulp, groundwood pulp, and chemi-mechanical pulp) are more and more often bleached with hydrogen peroxide. Di-thionite bleaching is also used either alone or together with peroxide bleaching, whereupon dithionite is either used as refiner bleaching or after-bleaching.
In the peroxide bleaching of pulp, mechanical pulp in particular, the decrease of opacity is clearly detectable, while the dithionite bleaching does not necessarily decrease the opacity. Generally, the lighter the level of bleaching the pulp, the lower the opacity of the pulp. The appended Fig. 1 that shows a variation in the opacity of spruce TMP, when peroxide is used to bleach pulp to various degrees of brightness mani-fests this. In certain paper grades, opacity is an important property. If we want to advance peroxide bleaching at the expense of dithionite bleaching, it would be im-portant to be able to optimize peroxide bleaching so that the opacity remains as high as possible while the brightness grows.
Generally, the chemicals used in the peroxide bleaching of mechanical pulps are hydrogen peroxide, lye (alkali), and waterglass. The purpose of the base is to in-crease the pH to a sufficiently high level, so that the hydrogen peroxide is dissoci-ated producing perhydroxyl anions. The purpose of the waterglass is to stabilize the hydrogen peroxide bleaching.
It is well known that peracetic acid can be produced in situ, for example, from acetanhydride or TAED (tetra acetyl ethylene diamine) or some other corresponding activator. One disadvantage of TAED is its high price and that it is a solid sub-stance. It would be necessary to disperse the TAED in water before adding it to the pulp, which makes it difficult to use. Furthermore, TAED contains nitrogen, which might constitute a problem for environmental protection. Acetanhydride is rela-tively cheap, but it would cause odour nuisance and be an inconvenient substance from the point of view of industrial safety. In addition, when fed into an alkaline 3 5 bleaching solution (NaOH + H202 + waterglass), it would readily cause silicate pre-cipitate and consume the lye.
Paper manufacture aims at ever-higher brightness levels. The brightness of paper can be affected, for example, by treating the paper with coating agents containing, among other things, pigments, binding agents, and plasticizing agents (JP
applica-tion 284598).
However, the use of several coating agents at the final stage of paper manufacture adds to the manufacturing costs.
The agent that affects the opacity of a technically useful pulp should be liquid and stable, and it should preferably have a suitable pH value, so that no silicate precipi-tate would form in the bleaching. Because of environmental matters, a nitrogen-free l0 substance would provide an additional benefit. The additive of the bleaching should also be cost-effective for the paper manufacturers. Consequently, a substance should be found for pulp bleaching, which, to fulfil the conditions mentioned above, is a reasonable, commercial chemical that is easy to get and can be added to the pulp as early as at the bleaching stage. Furthermore, attention should also be paid to the other effects of the substance, such as applicability in plant conditions.
The purpose of this invention is to find a useful substance that is used in pulp bleaching and that affects the opacity, fulfilling the conditions mentioned above.
The main features of the invention are disclosed by the appended Claims.
Surprisingly, we have now observed that, when a small portion of peracid is either added to the peroxide bleaching or with the purpose of finishing the peroxide bleaching, the opacity of pulp improves compared with pulp of a corresponding brightness level that is bleached with hydrogen peroxide alone. At the same time, we have observed that peracids scarcely increase the brightness.
The use of peracetic acid in bleaching chemical pulps is disclosed by the published Japanese application JP 57-21591, for example. However, bleaching processes like this aim at removing the lignin from the pulp and, in this case, the propose is in no way to adjust the opacity of the pulp.
Tappi publication, Vol. 48, No. 2 (2/1965), W.H. Rapson et al. Paper Bleaching - A
New Process, pp. 65-72, discloses a method for bleaching paper by using peracetic acid, among others. However, this method does not aim at improving the opacity of pulp, but increasing the brightness. Furthermore, the disclosed method uses consid-erable amounts of peracetic acid, about 1.2 - 2.5% (i.e., 12-25kg/ton of pulp). Such a portion can dissolve a considerable amount of lignin etc. from the pulp, where-upon the paper manufacturing process can be severely disturbed. The publication also reveals that the technical performance of the method deviates from our inven-lion.
applica-tion 284598).
However, the use of several coating agents at the final stage of paper manufacture adds to the manufacturing costs.
The agent that affects the opacity of a technically useful pulp should be liquid and stable, and it should preferably have a suitable pH value, so that no silicate precipi-tate would form in the bleaching. Because of environmental matters, a nitrogen-free l0 substance would provide an additional benefit. The additive of the bleaching should also be cost-effective for the paper manufacturers. Consequently, a substance should be found for pulp bleaching, which, to fulfil the conditions mentioned above, is a reasonable, commercial chemical that is easy to get and can be added to the pulp as early as at the bleaching stage. Furthermore, attention should also be paid to the other effects of the substance, such as applicability in plant conditions.
The purpose of this invention is to find a useful substance that is used in pulp bleaching and that affects the opacity, fulfilling the conditions mentioned above.
The main features of the invention are disclosed by the appended Claims.
Surprisingly, we have now observed that, when a small portion of peracid is either added to the peroxide bleaching or with the purpose of finishing the peroxide bleaching, the opacity of pulp improves compared with pulp of a corresponding brightness level that is bleached with hydrogen peroxide alone. At the same time, we have observed that peracids scarcely increase the brightness.
The use of peracetic acid in bleaching chemical pulps is disclosed by the published Japanese application JP 57-21591, for example. However, bleaching processes like this aim at removing the lignin from the pulp and, in this case, the propose is in no way to adjust the opacity of the pulp.
Tappi publication, Vol. 48, No. 2 (2/1965), W.H. Rapson et al. Paper Bleaching - A
New Process, pp. 65-72, discloses a method for bleaching paper by using peracetic acid, among others. However, this method does not aim at improving the opacity of pulp, but increasing the brightness. Furthermore, the disclosed method uses consid-erable amounts of peracetic acid, about 1.2 - 2.5% (i.e., 12-25kg/ton of pulp). Such a portion can dissolve a considerable amount of lignin etc. from the pulp, where-upon the paper manufacturing process can be severely disturbed. The publication also reveals that the technical performance of the method deviates from our inven-lion.
The use of peracids as a biocide is also disclosed by publication Kemia, No. 3 (1995), Jyri Maunuksela, Mikrobien torjunta peretikkahapolla (Microbe Prevention with Peracetic Acid), pp. 242-244. Such a method aims at destroying microbe popu-lations in the paper machine only. It is self evident that peracetic acid, which is known to be an effective biocide, prevents the functioning of microbes in the water circulation, if a sufficient amount is present. The method disclosed by the publica-tion uses a so-called equilibrium peracetic acid that contains a considerable amount of free acetic acid and hydrogen peroxide. The acetic acid and hydrogen peroxide that come with the peracid can disturb the paper manufacturing process.
Bleaching methods based on peracetic acid have also been presented, aiming at im-proving the brightness of the pulp compared with normal bleaching methods.
Such a method is presented, for example, by publication Pulp and Paper Magazine of Canada, Convention Issue, 1972, pp. 123-131, and by number 3/1968 of the same magazine in pages 51-60. The doses of peracid used by these methods are very high and, consequently, dissolve a considerable amount of lignin from the surfaces of the fibres. In addition, these methods aim at increasing the brightness of the pulp, i.e. at bleaching.
One difference between the treatments mentioned above and our invention in par ticular is that the peracid treatments implemented by the means disclosed by them fail to improve the opacity of the pulp; none of the publications mentioned above tried to achieve a considerable increase in the opacity either.
The invention relates to a method, in which the peracid is either added to the perox-ide bleaching or, preferably, after the peroxide bleaching, either to the storage tower of the bleached pulp or, for example, among the machine pulp in the paper machine.
Typically, the amount of peracid added to the pulp is about 1-3 kg/ton of pulp. Be-cause of its small amount, the peracid does not dissolve the lignin or the like from the pulp, whereupon it does not disturb the paper manufacturing process. It is espe-cially advantageous to use peracid solutions, which have been purified, so that they mainly contain the peracid in question and water only. In that case, the addition of peracid does not have a considerable effect on the pH value of the stock, and no extra COD gets into the process. The invention differs from the known methods based on peracid namely in that it does not aim at increasing the brightness but growing the opacity. A matter worth noticing in particular is that the method differs from the known bleaching treatments also in that the peracid doses used are very 3 5 small and the method tries to avoid the dissolution of organic matter from the fibres.
The method is not actually a bleaching method, and the chemicals used in the actual bleaching of the pulp have no effect whatsoever on the functioning of the invention.
Bleaching methods based on peracetic acid have also been presented, aiming at im-proving the brightness of the pulp compared with normal bleaching methods.
Such a method is presented, for example, by publication Pulp and Paper Magazine of Canada, Convention Issue, 1972, pp. 123-131, and by number 3/1968 of the same magazine in pages 51-60. The doses of peracid used by these methods are very high and, consequently, dissolve a considerable amount of lignin from the surfaces of the fibres. In addition, these methods aim at increasing the brightness of the pulp, i.e. at bleaching.
One difference between the treatments mentioned above and our invention in par ticular is that the peracid treatments implemented by the means disclosed by them fail to improve the opacity of the pulp; none of the publications mentioned above tried to achieve a considerable increase in the opacity either.
The invention relates to a method, in which the peracid is either added to the perox-ide bleaching or, preferably, after the peroxide bleaching, either to the storage tower of the bleached pulp or, for example, among the machine pulp in the paper machine.
Typically, the amount of peracid added to the pulp is about 1-3 kg/ton of pulp. Be-cause of its small amount, the peracid does not dissolve the lignin or the like from the pulp, whereupon it does not disturb the paper manufacturing process. It is espe-cially advantageous to use peracid solutions, which have been purified, so that they mainly contain the peracid in question and water only. In that case, the addition of peracid does not have a considerable effect on the pH value of the stock, and no extra COD gets into the process. The invention differs from the known methods based on peracid namely in that it does not aim at increasing the brightness but growing the opacity. A matter worth noticing in particular is that the method differs from the known bleaching treatments also in that the peracid doses used are very 3 5 small and the method tries to avoid the dissolution of organic matter from the fibres.
The method is not actually a bleaching method, and the chemicals used in the actual bleaching of the pulp have no effect whatsoever on the functioning of the invention.
The pulp can be bleached with dithionite, peroxide, dithionite and peroxide, or it can even be completely unbleached. Any chelation agents or other additives used in pulp manufacture have no effect on the functioning of the invention either.
The consistency of the pulp at the moment the peracid is added can be 1-40%;
the temperature can be 20-100°C. Depending on the process, the pH of the stock can be 3-11, preferably 4-8. If the peracid is added to alkaline peroxide bleaching, an ad-vantageous pH value is 9-11, however. A suitable reaction time for the peracid is 1-300 minutes depending on the process.
The method is well suited to the treatment of mechanical pulp, such as groundwood pulp (SGW, PGW) and refiner mechanical pulp (TMP), or to treat chemi-mechanical pulps (CTMP). The sort of wood used to manufacture the pulp has no importance to the functioning of the invention.
A suitable dose of peracid has been found to be 0.5-5 kg/ton of pulp, typically 1-3 kg/ton of pulp. The peracid used can be any peracid that reasonably dissolves in water. We have noticed that peracetic acid and perpropionic acid are preferable per-acids, and especially preferable are the peroxide-free distillates that are prepared from the equilibrium solutions of these. The manufacturing method of peracid has no effect on the functioning of the invention. Peracid solutions that are either puri-fied by distillation or some other method, or the equilibrium solutions of peracids can be used as peracid. Various mixtures of peracids are also usable. One modifica-tion of the invention can use a mixture of peracid and Caro's acid.
Example 1 CTMP pulp was bleached with peroxide in a normal manner. Peracids were added to the bleaching solution, the results are shown in Table 1.
Table 1 CTMP, bleaching solution: NaOH 24 kg +waterglass 20 kg + HzOz 30 kg/ton of pulp, 70°C, consistency 30%, 120 min, chelated pulp, peracid added to the bleaching, PAA =
peracetic, PPA = perpropionic acid Dosa eg , kg/ton Bri htness, % O aci of u1 ISO
None 78.4 64.9 PAA 2 79.1 67.2 PPA 2.2 78.3 70.7 The results show that, by using peracids, a distinctly higher opacity with the same brightness level is achieved than by using peroxide bleaching alone.
Example 2 Bleached CTMP pulp was treated with peracids, the results are shown in Table 2.
Table 1 Bleached CTMP
The consistency of the pulp at the moment the peracid is added can be 1-40%;
the temperature can be 20-100°C. Depending on the process, the pH of the stock can be 3-11, preferably 4-8. If the peracid is added to alkaline peroxide bleaching, an ad-vantageous pH value is 9-11, however. A suitable reaction time for the peracid is 1-300 minutes depending on the process.
The method is well suited to the treatment of mechanical pulp, such as groundwood pulp (SGW, PGW) and refiner mechanical pulp (TMP), or to treat chemi-mechanical pulps (CTMP). The sort of wood used to manufacture the pulp has no importance to the functioning of the invention.
A suitable dose of peracid has been found to be 0.5-5 kg/ton of pulp, typically 1-3 kg/ton of pulp. The peracid used can be any peracid that reasonably dissolves in water. We have noticed that peracetic acid and perpropionic acid are preferable per-acids, and especially preferable are the peroxide-free distillates that are prepared from the equilibrium solutions of these. The manufacturing method of peracid has no effect on the functioning of the invention. Peracid solutions that are either puri-fied by distillation or some other method, or the equilibrium solutions of peracids can be used as peracid. Various mixtures of peracids are also usable. One modifica-tion of the invention can use a mixture of peracid and Caro's acid.
Example 1 CTMP pulp was bleached with peroxide in a normal manner. Peracids were added to the bleaching solution, the results are shown in Table 1.
Table 1 CTMP, bleaching solution: NaOH 24 kg +waterglass 20 kg + HzOz 30 kg/ton of pulp, 70°C, consistency 30%, 120 min, chelated pulp, peracid added to the bleaching, PAA =
peracetic, PPA = perpropionic acid Dosa eg , kg/ton Bri htness, % O aci of u1 ISO
None 78.4 64.9 PAA 2 79.1 67.2 PPA 2.2 78.3 70.7 The results show that, by using peracids, a distinctly higher opacity with the same brightness level is achieved than by using peroxide bleaching alone.
Example 2 Bleached CTMP pulp was treated with peracids, the results are shown in Table 2.
Table 1 Bleached CTMP
5 After-treatment t = 50°C, 30 min, pH 7, consistency 5%
Dosa e, ton of u1 Bri htness, % O aci ISO
None 65.9 71.5 P~ 2 - 66.6 74.1 PPA 2.2 65.8 74.3 The results show that an after-treatment has an obvious effect on the opacity.
Example 3 So-called machine pulp taken from the plant and containing 16% of softwood pulp, 64% of TMP pulp, and 20% of coated broke (the basic pulp mixture was softwood:
TMP 20:80) was treated with peracetic acid. The softwood pulp was normal ECF
sulphate pulp. The TMP had been bleached with dithionite. The results are shown in Table 3.
Table 3 Pulp mixture:
Machine pulp Softwood pulp 16%
TMP 64%
Coated broke 20%
min, 70C, Cs 3.2%, the test was conducted b usin the water of the lant No. PAA, kg/tonpH TOC, kg/tonBrightness,Opacity, Note!
of u1 of u1 % ISO %
0 0 5.0 10.4 71.9 91.3 Untreated 1 0 4.9 9.6 71.6 91.8 30 min, at 70C
2 1 4.6 8.9 71.7 96.5 Distilled PAA
3 2 4.6 9.6 71.9 95.8 Distilled PAA
4 4 4.2 10.2 71.3 96.9 Distilled PAA
5 2 4.5 11.0 70.7 97.1 E uilibrium solution 6 1 5.0 9.5 71.6 93.7 Distilled PAA
Dosa e, ton of u1 Bri htness, % O aci ISO
None 65.9 71.5 P~ 2 - 66.6 74.1 PPA 2.2 65.8 74.3 The results show that an after-treatment has an obvious effect on the opacity.
Example 3 So-called machine pulp taken from the plant and containing 16% of softwood pulp, 64% of TMP pulp, and 20% of coated broke (the basic pulp mixture was softwood:
TMP 20:80) was treated with peracetic acid. The softwood pulp was normal ECF
sulphate pulp. The TMP had been bleached with dithionite. The results are shown in Table 3.
Table 3 Pulp mixture:
Machine pulp Softwood pulp 16%
TMP 64%
Coated broke 20%
min, 70C, Cs 3.2%, the test was conducted b usin the water of the lant No. PAA, kg/tonpH TOC, kg/tonBrightness,Opacity, Note!
of u1 of u1 % ISO %
0 0 5.0 10.4 71.9 91.3 Untreated 1 0 4.9 9.6 71.6 91.8 30 min, at 70C
2 1 4.6 8.9 71.7 96.5 Distilled PAA
3 2 4.6 9.6 71.9 95.8 Distilled PAA
4 4 4.2 10.2 71.3 96.9 Distilled PAA
5 2 4.5 11.0 70.7 97.1 E uilibrium solution 6 1 5.0 9.5 71.6 93.7 Distilled PAA
7 2 4.9 10.3 71.5 94.4 Distilled PAA
8 2 5.0 10.1 68.8 93.4 E uilibrium solution Distilled PAA = 3 8% of PAA, 1 % of HZOZ
Equilibrium solution = PAA 13%, acetic acid 22%, H202 15%
WO 00/77301 CA 02374673 2001-12-17 pCT~I00/00532 The results show that the opacity grew considerably because of the treatment with PAA. They also show that the equilibrium solution has an adverse effect on the brightness. The TOC values (total organic carbon) show that the treatment did not dissolve considerable amounts of organic matter from the fibres.
Equilibrium solution = PAA 13%, acetic acid 22%, H202 15%
WO 00/77301 CA 02374673 2001-12-17 pCT~I00/00532 The results show that the opacity grew considerably because of the treatment with PAA. They also show that the equilibrium solution has an adverse effect on the brightness. The TOC values (total organic carbon) show that the treatment did not dissolve considerable amounts of organic matter from the fibres.
Claims (9)
1. A method for treating mechanical pulp, characterized in that an aliphatic per-carboxylic acid is added to, the pulp, in the amount of 0.5 - 5 kg/ton of pulp, to af-fect the opacity.
2. A method according to Claim 1, characterized in that the amount of aliphatic percarboxylic acid that is added is 1- 3 kg/ton of pulp.
3. A method according to Claim 1 or 2, characterized in that the aliphatic per-carboxylic acid is selected from among performic acid, peracetic acid or perpropi-onic acid.
4. A method according to any of the preceding Claims, characterized in that the aliphatic percarboxylic acid is distilled or equilibrated peracetic acid.
5. A method according to Claim 1, characterized in that the aliphatic percar-boxylic acid is added to the pulp in connection with or after bleaching.
6. A method according to Claim 5, characterized in that the pulp has been bleached with hydrogen peroxide and/or dithionite.
7. A method according to Claim 1 or 5, characterized in that the aliphatic per-carboxylic acid is typically added at a pulp consistency of 1- 40%.
8. A method according to Claim 1, characterized in that a mixture -of aliphatic percarboxylic acid and Caro's acid is added to the pulp.
9. The use of aliphatic percarboxylic acid to improve the opacity of mechanical pulp, in which the amount of percarboxylic acid is 0.5 - 5 kg/ton of pulp.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI991366A FI107545B (en) | 1999-06-15 | 1999-06-15 | Process for processing mechanical masses |
| FI991366 | 1999-06-15 | ||
| PCT/FI2000/000532 WO2000077301A1 (en) | 1999-06-15 | 2000-06-14 | Method to improve the opacity of mechanical pulp by using aliphatic peroxyacids and use of peroxyacids to improve opacity |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2374673A1 true CA2374673A1 (en) | 2000-12-21 |
Family
ID=8554886
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002374673A Abandoned CA2374673A1 (en) | 1999-06-15 | 2000-06-14 | Method to improve the opacity of mechanical pulp by using aliphatic peroxyacids and use of peroxyacids to improve opacity |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP1244851B1 (en) |
| AT (1) | ATE239828T1 (en) |
| AU (1) | AU5224500A (en) |
| CA (1) | CA2374673A1 (en) |
| DE (1) | DE60002613T2 (en) |
| ES (1) | ES2193085T3 (en) |
| FI (1) | FI107545B (en) |
| NO (1) | NO20016083L (en) |
| WO (1) | WO2000077301A1 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI111745B (en) | 2001-12-19 | 2003-09-15 | Kemira Chemicals Oy | Improved board manufacturing process |
| GB2391011A (en) * | 2002-07-19 | 2004-01-28 | Crosmill Ltd | Bleaching cellulose suspensions |
| CN102113244B (en) | 2008-07-30 | 2015-12-02 | 微动公司 | For the method and apparatus of pulse-width signal process |
| FI127444B (en) | 2015-05-27 | 2018-06-15 | Kemira Oyj | Method for reducing pulp viscosity in production of dissolving pulp |
| FI127996B (en) | 2016-07-01 | 2019-07-15 | Kemira Oyj | A process for treating pulp |
| WO2019048698A1 (en) * | 2017-09-11 | 2019-03-14 | Kemira Oyj | Process for treating pulp |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1119546A (en) * | 1965-03-01 | 1968-07-10 | Paper Chemistry Inst | Improved method of treating fibrous material |
| US5589032A (en) * | 1992-09-21 | 1996-12-31 | North Carolina State University | Process for preparing a bleaching liquor containing percarboxylic acid and caro's acid |
| AU4271596A (en) * | 1995-12-19 | 1997-07-14 | Kvaerner Hymac Inc. | Process for treating refiner pulp |
-
1999
- 1999-06-15 FI FI991366A patent/FI107545B/en active
-
2000
- 2000-06-14 AU AU52245/00A patent/AU5224500A/en not_active Abandoned
- 2000-06-14 WO PCT/FI2000/000532 patent/WO2000077301A1/en active IP Right Grant
- 2000-06-14 DE DE60002613T patent/DE60002613T2/en not_active Expired - Fee Related
- 2000-06-14 AT AT00936926T patent/ATE239828T1/en not_active IP Right Cessation
- 2000-06-14 EP EP00936926A patent/EP1244851B1/en not_active Expired - Lifetime
- 2000-06-14 ES ES00936926T patent/ES2193085T3/en not_active Expired - Lifetime
- 2000-06-14 CA CA002374673A patent/CA2374673A1/en not_active Abandoned
-
2001
- 2001-12-13 NO NO20016083A patent/NO20016083L/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| ATE239828T1 (en) | 2003-05-15 |
| FI107545B (en) | 2001-08-31 |
| DE60002613D1 (en) | 2003-06-12 |
| WO2000077301A1 (en) | 2000-12-21 |
| NO20016083L (en) | 2002-02-14 |
| FI991366A (en) | 2000-12-16 |
| AU5224500A (en) | 2001-01-02 |
| EP1244851B1 (en) | 2003-05-07 |
| FI991366A0 (en) | 1999-06-15 |
| EP1244851A1 (en) | 2002-10-02 |
| NO20016083D0 (en) | 2001-12-13 |
| DE60002613T2 (en) | 2003-11-27 |
| ES2193085T3 (en) | 2003-11-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |