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EP 3 889 345 B1 |
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EUROPEAN PATENT SPECIFICATION |
(45) |
Mention of the grant of the patent: |
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01.02.2023 Bulletin 2023/05 |
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Date of filing: 14.05.2020 |
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International Patent Classification (IPC):
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OPTIMIZED PRODUCTION OF A CONTAINERBOARD TO BE USED AS FLUTING
OPTIMIERTE HERSTELLUNG VON WELLPAPPE ZUR VERWENDUNG ALS RIFFELUNG
PRODUCTION OPTIMISÉE D'UN CARTON-CAISSE DESTINÉ À ÊTRE UTILISÉ EN TANT QUE CANNELURE
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Designated Contracting States: |
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AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL
NO PL PT RO RS SE SI SK SM TR |
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Priority: |
14.05.2019 EP 19174469
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Date of publication of application: |
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06.10.2021 Bulletin 2021/40 |
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Application number of the earlier application in accordance with Art. 76 EPC: |
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20174696.3 / 3739115 |
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Proprietor: Billerud Aktiebolag (publ) |
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169 27 Solna (SE) |
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Inventors: |
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- NORDSTRÖM, Fredrik
652 26 Karlstad (SE)
- KULLANDER, Johan
653 50 Karlstad (SE)
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Representative: Kransell & Wennborg KB |
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P.O. Box 27834 115 93 Stockholm 115 93 Stockholm (SE) |
(56) |
References cited: :
EP-A1- 3 026 173
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WO-A1-2018/054957
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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TECHNICAL FIELD
[0001] The invention relates to a method of producing a containerboard to be used as fluting.
BACKGROUND
[0002] Neutral Sulfite Semi-Chemical (NSSC) pulping is an old process that it is well known
in the field of paper pulping and in use in many pulp mills around the world. One
of the reasons for using NSSC pulping is the high yield.
[0003] In NSSC pulping, the cooking liquor comprises sulfite, such as Na
2SO
3 or (NH
4)
2SO
3 and a base, such as NaOH or Na
2CO
3. "Neutral" means that the pH of the NSSC cooking liquor is generally between 6 and
10. Normally, the cooking time is between 0.5 and 3 hours and the cooking temperature
is 160-185 °C. However, the cooking time may be as short as 15 min, in particularly
in case of a relatively high temperature, such as ≥ 180 °C. The NSSC pulp comprises
comparatively high amounts of residual lignin, such as 15-20 %, which make the NSSC
pulp fibers stiff. The NSSC pulping is "semi-chemical" in the sense that it comprises
mechanical treatment/grinding (after the chemical (cooking) step).
[0004] The NSSC pulp is for example used to produce containerboard that is subsequently
corrugated to form the fluting of corrugated board.
[0005] Examples of mills using the NSSC pulping method are: BillerudKorsnäs' mills in Gruvön
(PM 6) and Skärblacka (PM4), Sweden; Mondi Swiecie S.A.'s mill in Swiecie (PM 4),
Poland; Mondi's (Powerflute's) mill in Koupio, Finland; Stora Enso Oyj's mill in Heinola,
Finland (Heinola Fluting Mill); S.C. Celrom S.A.'s mill in Drobeta, Romania; Packaging
Corp. of America's mills in Filer City (PM1, PM2 & PM3), Tomahawk (PM2 & PM4) and
Wallula (PM2), United States; Ilim Group's mills (PM1 and PM3) in Korjazma, Russia;
Permsky Karton's mill (PM2) in Perm, Russia; WestRock's mills in Longview (PM10) and
Stevenson (PM1 & PM2), United States; International Paper's mills in Mansfield (PM2)
and Pine Hill (PM2), United States; Georgia-Pacific LLC's mills in Big Island (PM1
& PM3) and Cedar Springs, United States; Cascades Containerboard Packaging's mill
in Trenton, Canada; Sappi's Tugela mill (PM2) in South Africa; Irving Lake Utopia
Paper's mill in St. George, Canada; Graphic Packaging International's mill in West
Monroe, United States; Greif Bros Corp's mill in Riverville, United States; Hood Container
Corp's mill in New Johnsonville, United States; and Sonoco's mill in Hartsville (PM10),
United States.
[0006] EP3026173 discloses a method of producing a containerboard (to be used as fluting) of increased
SCT strength from pulp comprising NSSC pulp. According to the method, a web formed
from the pulp comprising NSSC pulp is pressed in a shoe press, in which the line load
is at least 1200 kN/m.
[0007] Further, it is generally acknowledged in the prior art that the SCT strength of NSSC-based
containerboard to be used as fluting is increased when the NSSC pulp is subjected
to more refining. As an example, the rebuild of PM4 in Swiecie in 2015 involved a
rebuild of the refining system to allow for more refining of the NSSC pulp in order
to increase SCT strength. For the same purpose, Billerud AB (now BillerudKorsnäs AB)
increased the refining capacity in the NSSC mill (PM 6) in Gruvön, Sweden back in
2005. Powerflute's NSSC mill and Stora Enso's mill in Heinola improved their refining
capacity in 2010 and 2011, respectively.
SUMMARY
[0008] The object of the present disclosure is to optimize the production of NSSC-based
containerboard intended to be used as fluting.
[0009] To meet the above-mentioned object, there is provided a method of producing a containerboard
for use as fluting, comprising the steps of:
- forming a web from a pulp having a Schopper-Riegler (SR) value of 16.0-19.0 when measured
according to ISO 5267-1:1999, wherein at least 70% by dry weight of the pulp is NSSC
pulp;
- pressing the web in a press section comprising a shoe press, wherein the line load
in the shoe press is in the range of 1200-2000 kN/m; and
- drying the web from the press section in a drying section to obtain said containerboard.
[0010] The above range for the SR value of the pulp (16.0-19.0) reflects a very low degree
of refining, which means low energy consumption in that stage of the papermaking process.
The inventors have shown that a reduction of the refining energy results in a drastically
reduced energy consumption (i.e. steam consumption) in the drying section. Still,
the containerboard produced by the method of the present disclosure is surprisingly
strong. The inventors have thus identified an optimum at which strong containerboard
is produced at low energy consumption.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011]
Figure 1 shows the SCT index at 50% and 90% relative humidity (RH) of lab sheets formed
from NSSC pulp that had been subjected to different degrees of LC refining.
Figure 2 shows the CCT index at 50% and 90% relative humidity (RH) of lab sheets formed
from NSSC pulp that had been subjected to different degrees of LC refining.
Figure 3 shows the CMT index at 50% and 90% relative humidity (RH) of lab sheets formed
from NSSC pulp that had been subjected to different degrees of LC refining.
Figure 4 shows the tensile stiffness index at 50% and 90% relative humidity (RH) of
lab sheets formed from NSSC pulp that had been subjected to different degrees of LC
refining.
Figure 5 shows the degree of refining of the NSSC pulp and the specific steam consumption
in the drying section during a full-scale trial on the paper machine PM 6. As shown
in the figure, the degree of refining was first maintained at 60 kWh/tonne, then gradually
increased to 115 kW/h tonne and finally gradually decreased back to 60 kWh/tonne.
The x-axis shows the time.
DETAILED DESCRIPTION
[0012] There is thus provided a method of producing a containerboard. The containerboard
is intended for use as fluting (i.e. corrugated medium) in corrugated board. As understood
by the skilled person, the method is intended to be used on a full-scale paper machine,
i.e. a machine adapted to produce at least 50,000 tons of containerboard per year,
normally at least 100,000 tons of containerboard per year. The grammage of the containerboard
may be in the range of 100-240 g/m
2, such as 110-240 g/m
2, such as 120-240 g/m
2, such as 120-200 g/m
2 or 140-230 g/m
2, such as 150-230 g/m
2. Grammage is measured according to ISO 536:2012.
[0013] The present invention may have particular value when the grammage is relatively high,
e.g. 140-230 g/m
2.
[0014] Preferably, the geometric SCT index (measured according to ISO 9895:2008) of the
containerboard is 37.0-43.0 Nm/g, such as 37.0-42.0 Nm/g, such as 38.0-42.0 Nm/g,
such as 38.0-41.0 Nm/g.
[0015] To obtain the geometric SCT index, the compressive strength in the machine direction
(MD) and the cross direction (CD) of the containerboard is first measured using a
short-span compressive tester (SCT) measured according to ISO 9895:2008. To calculate
the compressive strength index, the compressive strength (N/m) is divided by the grammage.
The unit of the SCT index is thus Nm/g. The geometric SCT index is calculated as the
square root of the product of the SCT index in MD and CD:

[0016] The compressive strength is considered to be more important in CD than in MD. The
SCT index in the CD of the containerboard may for example be above 28 Nm/g, such as
at least 29 Nm/g. An upper limit for the SCT index in CD may for example be 32 Nm/g.
[0017] The method comprises the step of:
- forming a web from a pulp having a Schopper-Riegler (SR) value of 16.0-19.0 when measured
according to ISO 5267-1:1999, wherein at least 70% by dry weight of the pulp is NSSC
pulp, typically in a wire section (as conventional in paper making).
[0018] The SR value referred to above (and in the items) is the SR value that the pulp has
in the head box (i.e. the chamber from which the pulp is caused to flow onto the wire
of the wire section). To obtain this SR value, the pulp of the present disclosure
is typically subjected to low consistency (LC) refining between the NSSC pulping process
and the head box. The energy input of such LC refining may for example be 40-65 kWh/tonne,
such as 40-60 kWh/tonne. The "energy input" having the unit kWh/tonne means, in the
context of the present disclosure, the net energy input, which excludes the no-load
power. The "tonne" of the unit means tonne of dry fiber.
[0019] In a preferred embodiment, the SR value is 16.0-18.5.
[0020] Preferably, at least 80% by dry weight of the pulp is NSSC pulp. In one example,
at least 85% or 88% by dry weight of the pulp is NSSC pulp.
[0021] The NSSC pulp may comprise hardwood NSSC pulp. Preferably, at least 70% by dry weight
of the NSSC pulp is hardwood NSSC pulp, such as birch NSSC pulp. In one example, at
least 80% by dry weight of the NSSC pulp is hardwood NSSC pulp, such as birch NSSC
pulp.
[0022] It has been reported in the prior art that a relatively low yield of the NSSC pulp
is needed to obtain a large increase in strength. The results presented in the Examples
section are however obtained using a NSSC pulp of a relatively high yield, more precisely
about 82 %. The yield of the NSSC pulp of the present disclosure may thus be 75%-85%,
preferably 79%-85 %, such as 80-84%.
[0023] In addition to the NSSC pulp, the pulp may comprise recycled fibers, reject pulp
and/or clippings (typically corrugated box plant clippings). The above-mentioned LC
refining may be carried out before or after mixing with such other fibres.
[0024] "NSSC pulp" is obtained from "NSSC pulping", which in turn is defined in the background
section. The NSSC pulp of the present disclosure may for example be sodium-based NSSC
pulp, which means that the cooking liquor of the NSSC cook comprised Na
2SO
3.
[0025] In the method, the head box consistency may for example be 0.50%-1.20%, such as 0.80%-1.20%,
such as 0.90%-1.15%. The higher consistencies are particularly relevant when a large
proportion (e.g. at least 80%) of the NSSC pulp is derived from hardwood.
[0026] In one embodiment, the head box consistency is 1.05%-1.20% and the grammage of the
containerboard is 140-240 g/m
2, such as 140-200 g/m
2.
[0027] The method further comprises the step of:
- pressing the web in a press section comprising a shoe press.
[0028] The nip length in the shoe press may for example be 200-330 mm, such as 250-300 mm.
The shoe press is typically a double felted shoe press.
[0029] The shoe press may comprise a shoe press belt having discontinuous grooves. Such
a shoe press belt is commercially available. An example is the BlackBelt G DG marketed
by Valmet. Another example is Valmet Black Belt H DG marketed by Valmet. The hardness
of the elastomer in the shoe press belt may for example be 93-95 Shore A.
[0030] The line load in the shoe press is in the range of 1200-2000 kN/m, preferably 1300-2000
kN/m. A higher shoe press line load typically correlates with a higher geometric SCT
index.
[0031] In the shoe press, the web maybe subjected to a press impulse of 105-280 kPa
∗s, such as 105-190 kPa
∗s, such as 105-135 kPa
∗s. The highest press impulses are obtained when the line load is relatively high and
the web speed is relatively low (because of a high grammage of the produced containerboard).
[0032] The press section may comprise another press arranged upstream the shoe press. The
other press is typically double felted and may for example be a jumbo press or a shoe
press. The line load of the other press may be 100-300 kN/m, such as 150-250 kN/m,
in particular in case of a jumbo press.
[0033] Finally, the method further comprises the step of:
- drying the web from the press section in a drying section to obtain said containerboard.
The method of the present disclosure facilitates a reduced steam consumption in the
drying section and/or production at a relatively high speed, such as 700-850 m/min
or even 750-850 m/min. When the method of the present disclosure is carried out, the
steam consumption in the drying section may be as low as 0.95-1.15 tonne steam per
tonne paper. This steam is normally "medium pressure steam", which refers to steam
having a pressure of 6-11 bar, such as 6-10 bar, typically about 8 bar.
EXAMPLES
Lab sheets
[0034] NSSC pulp was obtained from a full-scale process of producing NSSC containerboard
(intended for fluting) in the Gruvön mill (PM 6), Sweden.
[0035] A first pulp sample was obtained from a position upstream the two LC refining steps
of the process. Accordingly, this pulp had been subjected to 0 kWh/tonne of LC refining.
[0036] A second and a third pulp sample were obtained from a position between the two LC
refining steps of the process. These pulp samples had been subjected to 20 and 40
kWh/tonne of LC refining, respectively.
[0037] Four more pulp samples were obtained from a position downstream the two LC refining
steps of the process. These pulp samples had been subjected to a total of 60, 80,
100 and 115 kWh/tonne of LC refining, respectively.
[0038] The composition of all samples was 100% NSSC pulp from birch.
[0039] The Schopper-Riegler (SR) value (also referred to as the "SR number") of all samples
was measured according to the standard ISO 5267-1:1999. The results of the measurements
are shown in table 1 below.
Table 1
Pulp sample # |
Specific refining energy (kWh/ton) |
SR number |
1 |
0 |
13.00 |
2 |
20 |
15.05 |
3 |
40 |
16.25 |
4 |
60 |
18.50 |
5 |
80 |
23.10 |
6 |
100 |
30.30 |
7 |
115 |
39.75 |
[0040] Raphid Köhten lab sheets having grammages of about 100 g/m
2 were produced from the pulp samples according to ISO 5269-2:2004. The actual grammages
were then measured. The following strength parameters of the lab sheets were measured
at 50% and 90% relative humidity: SCT (ISO 9895:2008); CCT (SCAN P-42); CMT (SS-EN
ISO 7263:2011); and tensile stiffness (SS-ISO 1924-3:2011). The measured strength
parameters were indexed by the measured grammages (by dividing a value by the grammage,
an indexed value is obtained).
[0041] The SCT is often considered to be the most important strength parameter.
[0042] Figure 1 shows the SCT index values, which increases with increased refining up to
60 kWh/tonne (corresponding to an SR value of 18.50). Between 60 and 80 kWh/tonne,
no increase was observed.
[0043] Also when looking at the other strength parameters, the benefit of refining up to
80 kWh/tonne is questionable (see figures 2-4).
Steam consumption
[0044] The pulp form which samples 1-4 were obtained was subjected to a total of 60 kWh/tonne
LC refining in the full-scale process. To obtain samples 5-7, the total LC refining
was successively increased up to 115 kWh/tonne. Subsequent to the LC refining, the
NSSC pulp was mixed with kraft pulp in a 90:10 dry weight ratio.
[0045] In the full-scale process, a web was formed in a forming section. The headbox consistency
was about 0.94%. The web was then pressed in a press section and dried in a drying
section.
[0046] The press section had two double felted nips; first a jumbo press (line load = 200
kN/m) and then a shoe press (line load = 1300 kN/m) with a shoe press belt having
discontinuous grooves (Valmet Black Belt H DG, void volume = 477 g/m
2, open area = 42%).
[0047] In figure 5, the steam consumption in the drying section following the increased
LC refining is plotted. It is shown that the increased refining resulted in a drastically
increased specific steam consumption. At 115 kWh/ton, the steam consumption was about
70% higher than at 60 kWh/ton.
Testing of paper from the full-scale process
[0048] Paper produced by the full-scale process (further described above) was obtained at
18:26 (see figure 5), which means that the paper was formed from pulp subjected to
a total of 60 kWh/tonne LC refining. Samples of the paper was tested. Despite the
moderate level of refining, the SCT index at 50% RH (ISO 9895:2008) of the sampled
paper was 56.0 Nm/g in MD and 29.4 Nm/g in CD, resulting in a geometric SCT index
of 40.59 Nm/g. The grammage was 120 g/m
2.
1. A method of producing a containerboard for use as fluting, comprising the steps of:
- forming a web from a pulp having, in the head box, a Schopper-Riegler (SR) value
of 16.0-19.0 when measured according to ISO 5267-1:1999, wherein at least 70% by dry
weight of the pulp is NSSC pulp;
- pressing the web in a press section comprising a shoe press, wherein the line load
in the shoe press is in the range of 1200-2000 kN/m; and
- drying the web from the press section in a drying section to obtain said containerboard.
2. The method according to claim 1, wherein the web is subjected to a press impulse of
105-190 kPa∗s in the shoe press.
3. The method according to claim 1 or 2, wherein the speed of the web is in the range
of 700-850 m/min, such as 750-850 m/min.
4. The method according to any one of the preceding claims, wherein grammage of the containerboard
is in the range of 100-240 g/m2, such as 140-230 g/m2, such as 150-230 g/m2, when measured according to ISO 536:2012.
5. The method according to any one of the preceding claims, wherein line load in the
shoe press is in the range of 1300-2000 kN/m.
6. The method according to any one of the preceding claims, wherein at least 80% by dry
weight of the pulp is NSSC pulp.
7. The method according to any one of the preceding claims, wherein at least 88% by dry
weight of the pulp is NSSC pulp.
8. The method according to any one of the preceding claims, wherein the yield of the
NSSC pulp is 75-85 %, such as 79-85 %.
9. The method according to any one of the preceding claims, wherein the pulp from which
the web is formed has a SR value of 16.0-18.5, such as 16.0-18.0, when measured according
to ISO 5267-1:1999.
10. The method according to any one of the preceding claims, wherein at least 70% by dry
weight of the NSSC pulp is hardwood NSSC pulp, such as birch NSSC pulp.
11. The method according to any one of the preceding claims, wherein at least 80% by dry
weight of the NSSC pulp is hardwood NSSC pulp, such as birch NSSC pulp.
12. The method according to any one of the preceding claims, wherein the steam consumption
in the drying section is below 1.20 tonne steam per tonne paper, such as 0.95-1.19
tonne steam per tonne paper, such as 1.00-1.19 tonne steam per tonne paper.
13. The method according to any one of the preceding claims, wherein the press section
comprises another press, such as a jumbo press or a shoe press, arranged upstream
the shoe press.
14. The method according to any one of the preceding claims, wherein the consistency of
the pulp in a head box used for forming the web is 0.50%-1.20%.
15. The method according to claim 10 or 11, wherein the consistency of the pulp in a head
box used for forming the web is 0.80%-1.20%, 0.90%-1.20%, such as 0.90%-1.15%.
1. Verfahren zur Herstellung von Wellpappe zur Verwendung als Riffelung, umfassend die
Schritte:
- Bilden einer Bahn aus einem Zellstoff, der in dem Stoffauflauf einen Schopper-Riegler-
(SR) Wert gemäß ISO 5267-1:1999 von 16,0-19,0 aufweist, wobei mindestens 70 % des
Trockengewichts des Zellstoffs NSSC-Zellstoff ist;
- Pressen der Bahn in einer Pressenpartie, die eine Schuhpresse umfasst, wobei die
Linienlast in der Schuhpresse im Bereich von 1200-2000 kN/m liegt; und
- Trocknen der Bahn aus der Pressenpartie in einer Trockenpartie, um die Wellpappe
zu erhalten.
2. Verfahren nach Anspruch 1, wobei die Bahn in der Schuhpresse einem Pressimpuls von
105-190 kPa*s ausgesetzt wird.
3. Verfahren nach Anspruch 1 oder 2, wobei die Geschwindigkeit der Bahn im Bereich von
700-850 m/min, beispielsweise 750-850 m/min, liegt.
4. Verfahren nach einem der vorhergehenden Ansprüche, wobei das gemessene Flächengewicht
gemäß ISO 536:2012 der Wellpappe im Bereich von 100-240 g/m2, beispielsweise 140-230 g/m2, beispielsweise 150-230 g/m2, liegt.
5. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Linienlast in der Schuhpresse
im Bereich von 1300-2000 kN/m liegt.
6. Verfahren nach einem der vorhergehenden Ansprüche, wobei mindestens 80 % des Trockengewichts
des Zellstoffs NSSC-Zellstoff ist.
7. Verfahren nach einem der vorhergehenden Ansprüche, wobei mindestens 88 % des Trockengewichts
des Zellstoffs NSSC-Zellstoff ist.
8. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Ausbeute an NSSC-Zellstoff
75-85 %, beispielsweise 79-85 %, beträgt.
9. Verfahren nach einem der vorangehenden Ansprüche, wobei der Zellstoff, aus dem die
Bahn gebildet wird, einen SR-Wert gemäß ISO 5267-1:1999 von 16,0-18,5, beispielsweise
16,0-18,0, aufweist.
10. Verfahren nach einem der vorangehenden Ansprüche, wobei mindestens 70 % des Trockengewichts
des NSSC-Zellstoffs Hartholz-NSSC-Zellstoff, beispielsweise Birken-NSSC-Zellstoff,
ist.
11. Verfahren nach einem der vorangehenden Ansprüche, wobei mindestens 80% des Trockengewichts
des NSSC-Zellstoffs Hartholz-NSSC-Zellstoff, wie etwa Birken-NSSC-Zellstoff, ist.
12. Verfahren nach einem der vorangehenden Ansprüche, wobei der Dampfverbrauch in der
Trockenpartie unter 1,20 Tonnen Dampf pro Tonne Papier, beispielsweise 0,95-1,19 Tonnen
Dampf pro Tonne Papier, beispielsweise 1,00-1,19 Tonnen Dampf pro Tonne Papier, liegt.
13. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Pressenpartie eine andere
Presse, wie eine Jumbopresse oder eine Schuhpresse, umfasst, die stromaufwärts der
Schuhpresse angeordnet ist.
14. Verfahren nach einem der vorangehenden Ansprüche, wobei die Konsistenz des Zellstoffs
in einem Stoffauflaufkasten, der zum Bilden der Bahn verwendet wird, 0,50 %-1,20 %
beträgt.
15. Verfahren nach Anspruch 10 oder 11, wobei die Konsistenz des Zellstoffs in einem Stoffauflaufkasten,
der zum Bilden der Bahn verwendet wird, 0,80 %-1,20 %, 0,90 %-1,20 %, beispielsweise
0,90 %-1,15 %, beträgt.
1. Procédé de production d'un carton-caisse destiné à être utilisé en tant que cannelure,
comprenant les étapes consistant à :
- former une bande à partir d'une pâte à papier ayant, dans la boîte de tête, une
valeur de Schopper-Riegler (SR) comprise entre 16,0 et 19,0 lorsqu'elle est mesurée
conformément à la norme ISO 5267-1:1999, dans lequel au moins 70 % à l'état sec de
la pâte à papier est une pâte de type NSSC ;
- presser la bande dans une section de presse comprenant une presse à sabot, dans
lequel la charge de ligne dans la presse à sabot se situe dans la plage allant de
1200 à 2000 kN/m ; et
- sécher la bande provenant de la section de presse dans une section de séchage afin
d'obtenir ledit carton-caisse.
2. Procédé selon la revendication 1, dans lequel la bande est soumise à une impulsion
de presse comprise entre 105 et 190 kPa*s dans la presse à sabot.
3. Procédé selon la revendication 1 ou la revendication 2, dans lequel la vitesse de
la bande se situe dans la plage allant de 700 à 850 m/min, telle que comprise entre
750 et 850 m/min.
4. Procédé selon l'une quelconque des revendications précédentes, dans lequel le grammage
du carton-caisse se situe dans la plage allant de 100 à 240 g/m2, tel que compris entre 140 et 230 g/m2, tel que compris entre 150 et 230 g/m2, lorsqu'il est mesuré conformément à la norme ISO 536:2012.
5. Procédé selon l'une quelconque des revendications précédentes, dans lequel la charge
de ligne dans la presse à sabot se situe dans la plage allant de 1300 à 2000 kN/m.
6. Procédé selon l'une quelconque des revendications précédentes, dans lequel au moins
80 % à l'état sec de la pâte à papier est une pâte à papier de type NSSC.
7. Procédé selon l'une quelconque des revendications précédentes, dans lequel au moins
88 % à l'état sec de la pâte à papier est une pâte à papier de type NSSC.
8. Procédé selon l'une quelconque des revendications précédentes, dans lequel le rendement
de la pâte à papier de type NSSC est compris entre 75 et 85 %, tel que compris entre
79 et 85 %.
9. Procédé selon l'une quelconque des revendications précédentes, dans lequel la pâte
à papier à partir de laquelle la bande est formée a une valeur SR comprise entre 16,0
et 18,5, telle que comprise entre 16,0 et 18,0, lorsqu'elle est mesurée conformément
à la norme ISO 5267-1:1999.
10. Procédé selon l'une quelconque des revendications précédentes, dans lequel au moins
70 % à l'état sec de la pâte à papier de type NSSC est une pâte à papier de type NSSC
de bois dur, telle qu'une pâte à papier de type NSSC de bouleau.
11. Procédé selon l'une quelconque des revendications précédentes, dans lequel au moins
80 % à l'état sec de la pâte à papier de type NSSC est une pâte à papier de type NSSC
de bois dur, telle qu'une pâte à papier de type NSSC de bouleau.
12. Procédé selon l'une quelconque des revendications précédentes, dans lequel la consommation
de vapeur dans la section de séchage est inférieure à 1,20 tonne de vapeur par tonne
de papier, telle que comprise entre 0,95 et 1,19 tonne de vapeur par tonne de papier,
telle que comprise entre 1,0 et 1,19 tonne de vapeur par tonne de papier.
13. Procédé selon l'une quelconque des revendications précédentes, dans lequel la section
de presse comprend une autre presse, telle qu'une presse jumbo ou une presse à sabot,
agencée en amont de la presse à sabot.
14. Procédé selon l'une quelconque des revendications précédentes, dans lequel la consistance
de la pâte à papier dans une boîte de tête utilisée pour la formation de la bande
est comprise entre 0,50 % et 1,20 %.
15. Procédé selon la revendication 10 ou la revendication 11, dans lequel la consistance
de la pâte à papier dans une boîte de tête utilisée pour la formation de la bande
est comprise entre 0,80 % et 1,20 %, comprise entre 0,90 % et 1,20 %, telle que comprise
entre 0,90 % et 1,15 %.
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only.
It does not form part of the European patent document. Even though great care has
been taken in compiling the references, errors or omissions cannot be excluded and
the EPO disclaims all liability in this regard.
Patent documents cited in the description