CA1315583C - Method of making mechanical pulp - Google Patents
Method of making mechanical pulpInfo
- Publication number
- CA1315583C CA1315583C CA000588744A CA588744A CA1315583C CA 1315583 C CA1315583 C CA 1315583C CA 000588744 A CA000588744 A CA 000588744A CA 588744 A CA588744 A CA 588744A CA 1315583 C CA1315583 C CA 1315583C
- Authority
- CA
- Canada
- Prior art keywords
- reject
- pulp
- refining
- kwh
- ton
- 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 - Fee Related
Links
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
- D21B1/00—Fibrous raw materials or their mechanical treatment
- D21B1/04—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres
- D21B1/12—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by wet methods, by the use of steam
- D21B1/14—Disintegrating in mills
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
- D21B1/00—Fibrous raw materials or their mechanical treatment
- D21B1/02—Pretreatment of the raw materials by chemical or physical means
- D21B1/021—Pretreatment of the raw materials by chemical or physical means by chemical means
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
- D21B1/00—Fibrous raw materials or their mechanical treatment
- D21B1/04—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres
- D21B1/12—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by wet methods, by the use of steam
- D21B1/14—Disintegrating in mills
- D21B1/16—Disintegrating in mills in the presence of chemical agents
Abstract
Abstract The making of mechanical pulp from softwood intended for coated light-weight paper (LWC), for uncoated cal-endered magazine paper (FSC) or the like is carried out in several steps as follows:
a) impregnation (2) of chips with water in combination with complex-forming agent;
b) refining-of the chips with double-disc refiner (3);
c) fractionating screening (6-10) of the pulp;
d) refining (12,14) of the screen reject in two steps, at high and, respectively, low concentration;
e) screening (15) of the refined reject and combining with the accept from the screening (6-10) according to step c).
a) impregnation (2) of chips with water in combination with complex-forming agent;
b) refining-of the chips with double-disc refiner (3);
c) fractionating screening (6-10) of the pulp;
d) refining (12,14) of the screen reject in two steps, at high and, respectively, low concentration;
e) screening (15) of the refined reject and combining with the accept from the screening (6-10) according to step c).
Description
~31~
METHOD OF MAKING MECHANICAL PULP
This invention relates to the making of mechanical pulp from softwood, intended for coated paper with low grammage, so-called LWC-paper (light weight coated), uncoated calendered magazine paper, so-called FSC-paper (filled supercalendered) or similar paper qualities.
These types of paper make very high demands on the properties of the pulp, because the paper must have high strength and low roughness. Obtaining good coated qualities, besides, requires low porosity. It is particularly important, that these papers have a smooth surface structure.
These types of paper normally contain both chemical and mechanical pulp~ The mechanical pulp component traditionally has been groundwood pulp. In recent years also thermomechanical pulp (TMP) has been used as an alternative to groundwood, but with limited success, because the energy consumption is relatively high compared with the manufacture of groundwood.
There exist, furthermore, several examples where the use of TMP
has resulted in unevenesses in the surface structure of the paper, which in its turn has resulted in poor coating and poor print-ability. These problems could be avoided only when the paper manufacturer took special measures to modify or eliminate the negative effects of the long fibre fraction in the thermo-mechanical pulp. This long fibre fraction adversely affects the smoothness of the paper, because it causes poor forming and also because it contains some long stiff fibres and has poor binding strength~
~, la ~31~3 The present invention provides a method of making mechanical pulp from softwood, which method comprises the steps:
a) impregnating softwood chips with water in combination with complex-forming agent within the pH range 5-9; b) subjecting the water-impregnated chips to a first refining step under pressure in a disc-refiner with two counter-rotating discs (double-disc refiner) to a long fibre content measured according to Bauer McNett fractionation of ~ 8 % on + 16 mesh and ~ 26 % on 16-30 mesh; c) fractionating screening the pulp so that a greater proportion of the long and stiff fibres of the pulp is found in the reject fraction, which amounts to 15-35 % of the pulp flow; d) refining this reject in two steps, the first one under pressure at high concentration, and the second one at low concentration to a fibre length distribution of the reject measured according to Bauer McMett characterization of ~ 10 ~ on + 16 mesh and ~ 27 ~ on 16-30 mesh; e) screening the refined reject and combining of the accept from this screening with the accept from the screening according to step c.
~y means of the present invention, the energy consumption for the manufacture of TMP is reduced and at the same time the pulp quality is improved. Consequently it is possible to increase the amount of mechanical pulp in the stock and to decrease the amount of chemical pulp, compared with the traditional formulas for the different paper qualities.
~3~5~3~
TMP for use in 1WC-paper and the like usually is manuf-actured by refining in two or more steps and subsequent screening and reject processing, bleaching and post-re-~ining.
According to the present invention, the softwood in the form of chips is impregnated with water in combination with complex-forming agent, preferably within the pH
range 5-9. The impregnation is followed by a refining under pressure in a doubl~disc refiner, i e a refiner with two counter-rotating discs. The energy input at the refining shall be 1800-2300 kWh/ton, preferably 1900-2100 kWh/ton. Thereafter a fractionated screening of the pulp is carried out, preferably in two steps with re-screening of the reject. After dewatering, the screen reject is refined in two steps. The first step takes place at high concentration under pressure, preferably in a disc-refiner of single-disc type, i.e.
with one stationary and one rotating disc. This refin-ing suitably is carried out with a specific energy input of 1000-2000 kWh/ton reject, preferably 1200-1500 kWh/
ton, The second step is carried out at low concentrat-ion, preferably in a pump-fed disc-refiner of the same type as in step one. The energy input here should be 50-300 kWh/tonf preferably 100-200 kWh/ton.
The invention implies, that the development of light--scattering coefficient can be maximized, and that the long fibre proportion can be minimiæed in an energy-saving way in the first and only refining step before screening. It is generally known that double~iSC
refiners yield a higher light-scattering coefficient and a lower long fibre proportion than single-disc re-finers It also is known that refining with high spec-ific energy input in a single refining step results in a pulp with shorter fibres than refining in two steps, unless special measures are taken to prevent 3 ~31~
the same. It further is known that chips having a low tempera-ture at the passage into a refiner, and thereby during the defibering phase, yield a pulp with shorter fibres and with higher light-scattering than preheated chips with the same ref:ining energy.
The special design of the screen room implies that a large proportion of the fibres in the pulp can be concentrated in the reject circuit. The reject fraction, thus, shall be 15-35 %, preferably 18-25 ~ of the total pulp flow. Owing to the refining of the reject at high concentration, the long stiff fibres become flexible. The subsequent refining at low concentration has the object to reduce the amount of long fibres in the pulp. It is generally known that refining at high concentration develops the binding strength of the pulp and increases its density, but reduces its long fibre content only to a small extent. This applies especially to high-concentra-tion refining of a long-fibre reject. It also is generally known that refining at low concentration of long-fibre reject results in substantial shortening of the fibres, unless special measures are taken for preventing this.
Preferably the final pulp has a long fibre content measured according to Bauer McNett characterization of ~ 1 % on + 16 mesh and ~ 21 % on 16-30 mesh.
The invention permits the total energy consumption for the refining is reduced not only, cause the refining is carried out in a single step in a double-disc refiner, but also because the final refining of the pulp takes place on the smaller ~' 3a 1315~83 amount of the pulp containing the long fibres, which are to be made flexible and shorter.
The invention is illustrated in the following with reference to an embodiment thereof, which is shown in the accompanying Figure by way of a flow chart.
~?
~' , ~ , ' .
~, ~ 3 ~
u The pretreatment of the raw material in the form of spruce chips is carried out by washing and atmospheric steaming 1 followed by water impregnation 2 with com-plex-forming agent present within the pH range 5-9.
The material thus pretreated is refined under pressure in a double~iSC refiner 3. The refining in this first step with 2000 kWh/ton yields a pulp with a freeness value according to CSF of 95 ml and a fibre length distribution according to Bauer Mc Nett characterizat-ion as follows 16 5 - 8 %
16/30 24 - 26 %
-200 26 - 28 %
After steam separation in a pressure cyclone 4, latency is removed in a vat 5. Thereafter a fractionating screening of the pulp is carried out in two steps in primary screens 6,7, which are pressure screens with mesh size 1,8 mm and, respectively, 1,6 mm. The reject withdrawal amounts to 20~ and, respectively, 25%.
The resulting accept has a freeness value according to CSF of 40 ml and a fibre distribution according to Bauer Mc Nett characterization as follows 16 0 - 2 %
16/~0 20 - 22 %
-200 38-40 %
The screen rejects combined in vat 8 are re-screened in two steps in secondary screens 9,10, which are pressure screens with mesh size 2,2 mm and, respectively, 2,0 mm.
The reject withdrawal amounts to 25% and, respectively, 30%.
The combined reject from these secondary screens 9,10 amounts to 19~ of the entire pulp flow and has the characteristics as follows:
` 13~8~
Freeness 450 ml CSF
+ 16 40 - 44 %
16/30 26 - 28 %
-200 4 - 6 %
This reject is passed through a dewatering press 11 where the concentration is increased to 20-35 %, where-after the reject is refined in a pressure refiner 12 with an energy input of 1250 kWh/ton. The resulting characteristics are as follows:
Freeness 110 ml CSF
+ 16 25 - 28 %
16/30 25 - 28 %
-200 8 - 11 %
This refined reject is diluted in a vat 13 to a con-centration of about 5% and refined in a single-disc refiner 14, which renders possible precision adjustment of the ~ap. With an energy input of 150 kWh/ton a reduction of the long fibre content by abo-lt 70% is obtained, and the reject shows the characteristic as follows:
Freeness 80 ml CSF
+ 16 8 - 10 %
16/30 25 - 27 %
-200 9 - 12 g The refined reject is screened in one step with a reject screen 15, which is a pressure screen with mesh size 1,8 mm with a reject withdrawal of 10 %.
The accept from this reject screen 15 and from the two secondary screens 9,10 combined with the accept from the two primary screens 6,7 constitute the final pulp, which is dewatered to be bleached with ditionite or peroxide to suitable diffuse blue reflectance.
6 ~ a t~ ~
The final unbleached pulp manufactured with a total refining energy of 2250 kWh/ton has the fibre charact-eristics as follows:
Freeness 50 ml CSF
~ 16 _ 1 %
+ 30 ~ 21 %
-200 7 34 %
and the pulp characteristics according to TAPPI test standard as follows:
Tensile index 7 52 Nm/g Tear index ~ 6,5 nMn /g Density ~ 450 m3/kg Smoothness ~ 110 ml/min Light-scattering ~ 64 m /kg The invention, of course, is not restricted to the embodiment described above, but can vary within the scope o~ the invention, especially as regards the design of the screen room and the location of the bleaching operation in the process scheme. The bleach-ing, for example, advantageously can be carried out on the refined pulp prior to the screening.
METHOD OF MAKING MECHANICAL PULP
This invention relates to the making of mechanical pulp from softwood, intended for coated paper with low grammage, so-called LWC-paper (light weight coated), uncoated calendered magazine paper, so-called FSC-paper (filled supercalendered) or similar paper qualities.
These types of paper make very high demands on the properties of the pulp, because the paper must have high strength and low roughness. Obtaining good coated qualities, besides, requires low porosity. It is particularly important, that these papers have a smooth surface structure.
These types of paper normally contain both chemical and mechanical pulp~ The mechanical pulp component traditionally has been groundwood pulp. In recent years also thermomechanical pulp (TMP) has been used as an alternative to groundwood, but with limited success, because the energy consumption is relatively high compared with the manufacture of groundwood.
There exist, furthermore, several examples where the use of TMP
has resulted in unevenesses in the surface structure of the paper, which in its turn has resulted in poor coating and poor print-ability. These problems could be avoided only when the paper manufacturer took special measures to modify or eliminate the negative effects of the long fibre fraction in the thermo-mechanical pulp. This long fibre fraction adversely affects the smoothness of the paper, because it causes poor forming and also because it contains some long stiff fibres and has poor binding strength~
~, la ~31~3 The present invention provides a method of making mechanical pulp from softwood, which method comprises the steps:
a) impregnating softwood chips with water in combination with complex-forming agent within the pH range 5-9; b) subjecting the water-impregnated chips to a first refining step under pressure in a disc-refiner with two counter-rotating discs (double-disc refiner) to a long fibre content measured according to Bauer McNett fractionation of ~ 8 % on + 16 mesh and ~ 26 % on 16-30 mesh; c) fractionating screening the pulp so that a greater proportion of the long and stiff fibres of the pulp is found in the reject fraction, which amounts to 15-35 % of the pulp flow; d) refining this reject in two steps, the first one under pressure at high concentration, and the second one at low concentration to a fibre length distribution of the reject measured according to Bauer McMett characterization of ~ 10 ~ on + 16 mesh and ~ 27 ~ on 16-30 mesh; e) screening the refined reject and combining of the accept from this screening with the accept from the screening according to step c.
~y means of the present invention, the energy consumption for the manufacture of TMP is reduced and at the same time the pulp quality is improved. Consequently it is possible to increase the amount of mechanical pulp in the stock and to decrease the amount of chemical pulp, compared with the traditional formulas for the different paper qualities.
~3~5~3~
TMP for use in 1WC-paper and the like usually is manuf-actured by refining in two or more steps and subsequent screening and reject processing, bleaching and post-re-~ining.
According to the present invention, the softwood in the form of chips is impregnated with water in combination with complex-forming agent, preferably within the pH
range 5-9. The impregnation is followed by a refining under pressure in a doubl~disc refiner, i e a refiner with two counter-rotating discs. The energy input at the refining shall be 1800-2300 kWh/ton, preferably 1900-2100 kWh/ton. Thereafter a fractionated screening of the pulp is carried out, preferably in two steps with re-screening of the reject. After dewatering, the screen reject is refined in two steps. The first step takes place at high concentration under pressure, preferably in a disc-refiner of single-disc type, i.e.
with one stationary and one rotating disc. This refin-ing suitably is carried out with a specific energy input of 1000-2000 kWh/ton reject, preferably 1200-1500 kWh/
ton, The second step is carried out at low concentrat-ion, preferably in a pump-fed disc-refiner of the same type as in step one. The energy input here should be 50-300 kWh/tonf preferably 100-200 kWh/ton.
The invention implies, that the development of light--scattering coefficient can be maximized, and that the long fibre proportion can be minimiæed in an energy-saving way in the first and only refining step before screening. It is generally known that double~iSC
refiners yield a higher light-scattering coefficient and a lower long fibre proportion than single-disc re-finers It also is known that refining with high spec-ific energy input in a single refining step results in a pulp with shorter fibres than refining in two steps, unless special measures are taken to prevent 3 ~31~
the same. It further is known that chips having a low tempera-ture at the passage into a refiner, and thereby during the defibering phase, yield a pulp with shorter fibres and with higher light-scattering than preheated chips with the same ref:ining energy.
The special design of the screen room implies that a large proportion of the fibres in the pulp can be concentrated in the reject circuit. The reject fraction, thus, shall be 15-35 %, preferably 18-25 ~ of the total pulp flow. Owing to the refining of the reject at high concentration, the long stiff fibres become flexible. The subsequent refining at low concentration has the object to reduce the amount of long fibres in the pulp. It is generally known that refining at high concentration develops the binding strength of the pulp and increases its density, but reduces its long fibre content only to a small extent. This applies especially to high-concentra-tion refining of a long-fibre reject. It also is generally known that refining at low concentration of long-fibre reject results in substantial shortening of the fibres, unless special measures are taken for preventing this.
Preferably the final pulp has a long fibre content measured according to Bauer McNett characterization of ~ 1 % on + 16 mesh and ~ 21 % on 16-30 mesh.
The invention permits the total energy consumption for the refining is reduced not only, cause the refining is carried out in a single step in a double-disc refiner, but also because the final refining of the pulp takes place on the smaller ~' 3a 1315~83 amount of the pulp containing the long fibres, which are to be made flexible and shorter.
The invention is illustrated in the following with reference to an embodiment thereof, which is shown in the accompanying Figure by way of a flow chart.
~?
~' , ~ , ' .
~, ~ 3 ~
u The pretreatment of the raw material in the form of spruce chips is carried out by washing and atmospheric steaming 1 followed by water impregnation 2 with com-plex-forming agent present within the pH range 5-9.
The material thus pretreated is refined under pressure in a double~iSC refiner 3. The refining in this first step with 2000 kWh/ton yields a pulp with a freeness value according to CSF of 95 ml and a fibre length distribution according to Bauer Mc Nett characterizat-ion as follows 16 5 - 8 %
16/30 24 - 26 %
-200 26 - 28 %
After steam separation in a pressure cyclone 4, latency is removed in a vat 5. Thereafter a fractionating screening of the pulp is carried out in two steps in primary screens 6,7, which are pressure screens with mesh size 1,8 mm and, respectively, 1,6 mm. The reject withdrawal amounts to 20~ and, respectively, 25%.
The resulting accept has a freeness value according to CSF of 40 ml and a fibre distribution according to Bauer Mc Nett characterization as follows 16 0 - 2 %
16/~0 20 - 22 %
-200 38-40 %
The screen rejects combined in vat 8 are re-screened in two steps in secondary screens 9,10, which are pressure screens with mesh size 2,2 mm and, respectively, 2,0 mm.
The reject withdrawal amounts to 25% and, respectively, 30%.
The combined reject from these secondary screens 9,10 amounts to 19~ of the entire pulp flow and has the characteristics as follows:
` 13~8~
Freeness 450 ml CSF
+ 16 40 - 44 %
16/30 26 - 28 %
-200 4 - 6 %
This reject is passed through a dewatering press 11 where the concentration is increased to 20-35 %, where-after the reject is refined in a pressure refiner 12 with an energy input of 1250 kWh/ton. The resulting characteristics are as follows:
Freeness 110 ml CSF
+ 16 25 - 28 %
16/30 25 - 28 %
-200 8 - 11 %
This refined reject is diluted in a vat 13 to a con-centration of about 5% and refined in a single-disc refiner 14, which renders possible precision adjustment of the ~ap. With an energy input of 150 kWh/ton a reduction of the long fibre content by abo-lt 70% is obtained, and the reject shows the characteristic as follows:
Freeness 80 ml CSF
+ 16 8 - 10 %
16/30 25 - 27 %
-200 9 - 12 g The refined reject is screened in one step with a reject screen 15, which is a pressure screen with mesh size 1,8 mm with a reject withdrawal of 10 %.
The accept from this reject screen 15 and from the two secondary screens 9,10 combined with the accept from the two primary screens 6,7 constitute the final pulp, which is dewatered to be bleached with ditionite or peroxide to suitable diffuse blue reflectance.
6 ~ a t~ ~
The final unbleached pulp manufactured with a total refining energy of 2250 kWh/ton has the fibre charact-eristics as follows:
Freeness 50 ml CSF
~ 16 _ 1 %
+ 30 ~ 21 %
-200 7 34 %
and the pulp characteristics according to TAPPI test standard as follows:
Tensile index 7 52 Nm/g Tear index ~ 6,5 nMn /g Density ~ 450 m3/kg Smoothness ~ 110 ml/min Light-scattering ~ 64 m /kg The invention, of course, is not restricted to the embodiment described above, but can vary within the scope o~ the invention, especially as regards the design of the screen room and the location of the bleaching operation in the process scheme. The bleach-ing, for example, advantageously can be carried out on the refined pulp prior to the screening.
Claims (12)
1. A method of making mechanical pulp from softwood, which method comprises the steps:
a) impregnating softwood chips with water in combination with complex-forming agent within the pH range 5-9;
b) subjecting the water-impregnated chips to a first refining step under pressure in a disc-refiner with two counter-rotating discs (double-disc refiner) to a long fibre content measured according to Bauer McNett fractionation of ? 8 % on +
16 mesh and ? 26 % on 16-30 mesh;
c) fractionating screening the pulp so that a greater proportion of the long and stiff fibres of the pulp is found in the reject fraction, which amounts to 15-35 % of the pulp flow;
d) refining this reject in two steps, the first one under pressure at high concentration, and the second one at low concentration to a fibre length distribution of the reject measured according to Bauer McNett characterization of ? 10 % on + 16 mesh and ? 27 % on 16-30 mesh;
e) screening the refined reject and combining of the accept from this screening with the accept from the screening according to step c.
a) impregnating softwood chips with water in combination with complex-forming agent within the pH range 5-9;
b) subjecting the water-impregnated chips to a first refining step under pressure in a disc-refiner with two counter-rotating discs (double-disc refiner) to a long fibre content measured according to Bauer McNett fractionation of ? 8 % on +
16 mesh and ? 26 % on 16-30 mesh;
c) fractionating screening the pulp so that a greater proportion of the long and stiff fibres of the pulp is found in the reject fraction, which amounts to 15-35 % of the pulp flow;
d) refining this reject in two steps, the first one under pressure at high concentration, and the second one at low concentration to a fibre length distribution of the reject measured according to Bauer McNett characterization of ? 10 % on + 16 mesh and ? 27 % on 16-30 mesh;
e) screening the refined reject and combining of the accept from this screening with the accept from the screening according to step c.
2. A method as defined in claim l, wherein the final pulp has a long fibre content measured according to Bauer McNett characterization of ? 1 % on + 16 mesh and ? 21 % on 16-30 mesh.
3. A method as defined in claim 1, wherein energy input in the first refining step is 1800-2300 kWh/ton.
4. A method as defined in claim 1, wherein energy input in the first refining step is 1900-2100 kWh/ton.
5. A method as defined in claim 1, wherein in step c the reject fraction amounts to 18-25 % of the pulp flow.
6. A method as defined in any one of claims 1 to 5, wherein a specific energy input is made, at the reject-refining in high concentration, of 1000-2000 kWh/ton of reject.
7. A method as defined in claim 6, wherein the specific energy input is 1200-1500 kWh/ton of reject.
8. A method as defined in any one of claims 1 to 5 and 7, wherein a specific energy input is made, at the reject-refining in low concentration, of 50-300 kWh/ton of reject.
9. A method as defined in claim 8, wherein the specific energy input is 100-200 kWh/ton of reject.
10. A method as defined in any one of claims 1 to 5, 7 and 9 which includes the further step of incorporating the obtained mechanical pulp into coated light weight paper.
11. A method as defined in any one of claims 1 to 5, 7 and 9 which includes the further step of incorporating the obtained mechanical pulp into uncoated calendered magazine paper.
12. A method as defined in any one of claims 1 to 5, 7 and 9 which includes the further step of incorporating the obtained mechanical pulp into filled supercalendered paper.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE8800200A SE459924B (en) | 1988-01-22 | 1988-01-22 | SET FOR MANUFACTURE OF MECHANICAL MASS |
| SE8800200-1 | 1988-01-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1315583C true CA1315583C (en) | 1993-04-06 |
Family
ID=20371140
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000588744A Expired - Fee Related CA1315583C (en) | 1988-01-22 | 1989-01-20 | Method of making mechanical pulp |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US5145010A (en) |
| AU (1) | AU2925089A (en) |
| CA (1) | CA1315583C (en) |
| NZ (1) | NZ227679A (en) |
| SE (1) | SE459924B (en) |
| WO (1) | WO1989006717A1 (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5405499A (en) * | 1993-06-24 | 1995-04-11 | The Procter & Gamble Company | Cellulose pulps having improved softness potential |
| US5679218A (en) * | 1994-07-29 | 1997-10-21 | The Procter & Gamble Company | Tissue paper containing chemically softened coarse cellulose fibers |
| AT374U1 (en) * | 1994-11-29 | 1995-09-25 | Peter Mueller Ges M B H & Co K | FIBER UNITS WITH Roughened Surface Obtained By Milling Wooden Pieces |
| US6107014A (en) * | 1998-06-09 | 2000-08-22 | Eastman Kodak Company | Raw stock for photographic paper |
| SE513140C2 (en) * | 1998-11-19 | 2000-07-10 | Valmet Fibertech Ab | Procedure for producing upgraded newsprint pulp to SC / LWC quality |
| FI113670B (en) * | 1999-12-09 | 2004-05-31 | Upm Kymmene Corp | Process for producing printing paper |
| FI113552B (en) * | 1999-12-09 | 2004-05-14 | Upm Kymmene Corp | Process for producing printing paper |
| US6391532B1 (en) | 2000-04-07 | 2002-05-21 | Eastman Kodak Company | Photographic paper containing calcium carbonate |
| SE519462C2 (en) * | 2001-06-21 | 2003-03-04 | Holmen Ab | Process for Preparation of Bleached Thermomechanical Pulp (TMP) or Bleached Chemithermomechanical Pulp (CTMP) |
| SE0202032D0 (en) * | 2002-07-01 | 2002-07-01 | Skogsind Tekn Foskningsinst | Method for manufacturing mechanical or chemical-mechanical pulp and a device for manufacturing the same |
| FI20022050A (en) * | 2002-11-18 | 2004-05-19 | M Real Oyj | Method and apparatus for making mechanical fiber |
| FI121311B (en) * | 2005-05-03 | 2010-09-30 | M Real Oyj | A process for the preparation of a mechanical pulp for use in the manufacture of paper and board |
| FI125948B (en) * | 2009-06-18 | 2016-04-29 | Stora Enso Oyj | Papermaking procedure |
| CA2824076A1 (en) | 2012-08-21 | 2014-02-21 | University Of New Brunswick | System and method for reclaiming rejects in sulfite pulping |
| GB201304717D0 (en) | 2013-03-15 | 2013-05-01 | Imerys Minerals Ltd | Paper composition |
| EP3458644B1 (en) * | 2016-05-20 | 2021-07-14 | Scandinavian Fibre Boards A/S | A wet-formed solid porous body, a process for controlling structural and mechanical properties in the manufacture of a solid porous body and paper manufacture, and a method of wet-forming the solid porous body |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA915956A (en) * | 1970-04-13 | 1972-12-05 | F. Crotogino Hermann | Low energy mechanical pulping of wood materials by multiphase operations |
| US3791917A (en) * | 1973-03-07 | 1974-02-12 | Bird Machine Co | Process for producing kraft paper laminate of top stock and base stock layers |
| SE413684C (en) * | 1974-09-23 | 1987-05-07 | Mo Och Domsjoe Ab | PROCEDURE FOR PREPARING CELLULOSAMASSA IN THE REPLACEMENT AREA 65-95% |
| US4187141A (en) * | 1975-02-24 | 1980-02-05 | Alf Societe Anonyme | Method of producing bleached mechanical pulp |
| SE413601B (en) * | 1976-06-30 | 1980-06-09 | American Defibrator | SET FOR MANUFACTURING THE FIBER MASS IN A UNDERPRESSED MALAWARE AND DEVICE FOR IMPLEMENTATION OF THE SET |
| SE433954B (en) * | 1980-03-25 | 1984-06-25 | Mo Och Domsjoe Ab | PROCEDURES AND DEVICES FOR REDUCING THE PREPARATION OF GRINDING MACHINES FROM WOODWOODS IN STONE GRINDING GROUPS REMOVE AND SPETOR YEAR REGULATION OF THE FREENESS OF THE MASS |
| US4402918A (en) * | 1980-12-22 | 1983-09-06 | General Electric Company | Reclamation process for water-borne uranium |
| SE441282B (en) * | 1984-02-22 | 1985-09-23 | Mo Och Domsjoe Ab | PROCEDURE FOR THE PREPARATION OF IMPROVED HOG REPLACEMENT MASS |
| SE441758B (en) * | 1984-04-03 | 1985-11-04 | Sunds Defibrator | SET AND DEVICE FOR CONTINUOUS TREATMENT OF MATERIAL SUSPENSIONS |
| SE456430B (en) * | 1985-11-06 | 1988-10-03 | Sunds Defibrator | SET FOR MAKING MECHANICAL MASS |
| US4718980A (en) * | 1985-12-30 | 1988-01-12 | Weyerhaeuser Company | Interstage treatment of mechanical pulp |
| FI75200B (en) * | 1986-07-04 | 1988-01-29 | Valmet Oy | FOERFARANDE VID PAPPERSFRAMSTAELLNINGSPROCESS FOER FOERBAETTRING AV EGENSKAPER HOS PAPPERET, SAERSKILT DESS RETENTION. |
| US4732650A (en) * | 1986-09-15 | 1988-03-22 | The Dow Chemical Company | Bleaching of cellulosic pulps using hydrogen peroxide |
-
1988
- 1988-01-22 SE SE8800200A patent/SE459924B/en not_active IP Right Cessation
-
1989
- 1989-01-11 WO PCT/SE1989/000004 patent/WO1989006717A1/en unknown
- 1989-01-11 AU AU29250/89A patent/AU2925089A/en not_active Abandoned
- 1989-01-11 US US07/488,037 patent/US5145010A/en not_active Expired - Fee Related
- 1989-01-20 NZ NZ227679A patent/NZ227679A/en unknown
- 1989-01-20 CA CA000588744A patent/CA1315583C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| WO1989006717A1 (en) | 1989-07-27 |
| SE8800200D0 (en) | 1988-01-22 |
| US5145010A (en) | 1992-09-08 |
| SE459924B (en) | 1989-08-21 |
| AU2925089A (en) | 1989-08-11 |
| NZ227679A (en) | 1990-02-26 |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |