Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
1
CELLULOSE MATERIAL PLASTICIZATION AND VISCOSITY
CONTROLLED CELLULOSIC MATERIAL
Technical field
This invention relates to a method and a system for manufacturing viscosity
controlled cellulosic material. This invention further relates to a viscosity
controlled cellulosic material.
Background
Cellulose, which is an abundant natural raw material, is a polysaccharide
consisting of a linear chain of a couple of thousands to ten thousand linked
D-glucose units. Cellulose can be modified, for example, to man-made fibers
(MMF). At the moment, viscose filaments are the most commonly produced
MMF filaments.
Summary
The present invention discloses a novel solution for manufacturing viscosity
controlled cellulosic material. According to the novel method, it is possible
to
use a wood-based cellulosic material and treat the wood-based cellulosic
material in a continuous process in order to obtain viscosity controlled
cellulosic material having a viscosity value in a range between 150 ml/g and
500 ml/g.
Aspects of the invention are characterized by what is stated in the
independent claims. Various embodiments of the invention are disclosed in
the dependent claims.
A method for producing viscosity controlled cellulosic material having a
viscosity value in a range between 150 ml/g and 500 ml/g in a continuous
process can comprise the following steps:
i) forming a cellulose-water mixture comprising water and chemically
treated wood-based cellulosic material, such as a bleached kraft pulp
and/or a bleached sulfite pulp and/or a bleached soda pulp, the
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
2
cellulose-water mixture having a dry matter content between 3% and
20%,
ii) treating the formed cellulose-water mixture in a plasticization
step at
a temperature between 130 C and 200 C and a pressure between 3
bar and 15 bar, preferably between 5 bar and 10 bar, at least 5
minutes and 120 minutes at the most, while
- mixing the cellulose-water mixture, and
- feeding hot water and/or water steam to the cellulose-water
mixture,
thereby obtaining a treated mixture, and
iii) depressurizing the treated mixture after the plasticization step
in a
depressurizing step in a controlled manner without a steam explosion
to maintain fiber integrity,
thereby obtaining the viscosity controlled cellulosic material having a
viscosity value in a range between 150 ml/g and 500 ml/g.
A system for producing viscosity controlled cellulosic material having a
viscosity value in a range between 150 ml/g and 500 ml/g in a continuous
process, can comprise the following means:
- means for forming a cellulose-water mixture,
- a continuous reactor, such as a continuous kneader reactor, for
treating the cellulose-water mixture in a plasticization step at a
temperature between 130 C and 200 C,
- mixing means for mixing the cellulose-water mixture during the
plasticization step,
- heating means for increasing temperature of the cellulose-water
mixture in the continuous reactor, such as a feeder to feed water
steam to the continuous reactor, and
- means for depressurizing the treated mixture in a controlled manner
without a steam explosion after the plasticization step,
thereby obtaining the viscosity controlled cellulosic material having a
viscosity value in a range between 150 ml/g and 500 ml/g.
The system can comprise means for circulating at least part of a filtrate
obtained from the plasticization step to the continuous reactor. This can
decrease chemical consumption of the process and speed up the
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
3
plasticization step and, hence, decrease manufacturing costs. Therefore, a
production efficiency can be improved.
A viscosity controlled cellulosic material having a viscosity value in a range
between 150 ml/g and 500 ml/g can have an R18 solubility between 60% and
87%. Therefore, the method for producing viscosity controlled cellulosic
material having a viscosity value in a range between 150 ml/g and 500 ml/g
in a continuous process can be a method for producing viscosity controlled
cellulosic material having a viscosity value in a range between 150 ml/g and
500 ml/g and an R18 solubility between 60 and 87% in a continuous process.
The plasticization step can be implemented by treating the formed cellulose-
water mixture in a continuous reactor, such as a continuous screw reactor.
The continuous screw reactor can be, for example, a horizontal screw reactor
or a vertical screw reactor. Advantageously, the continuous reactor is a
kneader reactor. Therefore, the material to be treated can be conveyed easily
and efficiently forward. Alternatively, the plasticization step can be
implemented without the screw reactor, for example, by treating the formed
cellulose-water mixture in a device comprising chambers separated with
each other.
During the plasticization step, water steam can be fed continuously or
substantially continuously into the continuous reactor.
Advantageously, the following combination of parameters is used in the
method: The duration of the plasticization step can be at least 5 minutes or
at
least 6 minutes. Further, the duration of the plasticization step can be 50
minutes at the most, more preferably 25 minutes at the most, and most
preferably 20 minutes at the most. Further, the temperature of the
.. plasticization step can be at least 140 C. Further, the temperature of the
plasticization step can be 180 C at the most, more preferably 170 C at the
most. Further, the pressure of the plasticization step can be at least 5 bars.
Further, the pressure of the plasticization step can be less than 10 bar. The
technical effect on said combination of parameters is that it can improve
production efficiency as well as quality of the obtained viscosity controlled
cellulosic material.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
4
In order to further improve the method, pH of the cellulose-water mixture can
be at least 1, preferably at least 2. Further, pH of the cellulose-water
mixture
can be 6 at the most, preferably 5 at the most. Most preferably, pH of the
cellulose-water mixture is between 2 and 5.
A viscosity value of the chemically treated wood-based cellulosic material,
determined from the cellulose-water mixture before the plasticization step
can be at least 400 ml/g, preferably at least 450 ml/g. In addition, a
viscosity
value of the chemically treated wood-based cellulosic material determined
from the cellulose-water mixture before the plasticization step can be 1400
ml/g at the most, more preferably 1200 ml/g at the most. Said viscosity
range can improve reactions during the plasticization step and, hence,
decrease a reaction time. Thus, said viscosity range can improve production
efficiency of the method.
The dry matter content of the cellulose-water mixture can be at least 3%,
more preferably at least 5%. Further, the dry matter content of the cellulose-
water mixture can be less than 20% more preferably less than 17% and most
preferably less than 14%. Thanks to this quite low consistency, an effect of
mixing on the plasticization step can be improved. Further, the quality of the
obtained viscosity controlled cellulosic material can be improved.
ISO Brightness of the chemically treated wood-based cellulosic material,
determined before the plasticization step, can be at least 70%, more
preferably at least 86%. Thus, a brightness of the end product can be
improved. Further, thanks to said brightness of the raw material, chemical
consumption can be decreased.
A hemicellulose content of the chemically treated wood-based cellulosic
material in the cellulose-water mixture can be at least 0.5%, more preferably
at least 3%, for example between 3 % and 10 %, and most preferably equal
or less than 33%, for example from 10% to 33%, based on a dry weight of
the chemically treated wood-based cellulosic material. This kind of
hemicellulose content can improve a yield and a material efficiency of the
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
manufacturing process, and the hemicelluloses can work as an internal
activator causing faster reactions.
An extractive content of the chemically treated wood-based cellulosic
5 material measured from the cellulose-water mixture before the
plasticization
step can be less than 0.4%, more preferably less than 0.2%, based on a dry
weight of the chemically treated wood-based cellulosic material in the
cellulose-water mixture. A low content of extractives can improve quality of
the obtained viscosity controlled cellulosic material and a runnability of the
manufacturing process.
An ash content of the chemically treated wood-based cellulosic material
measured from the cellulose-water mixture can be less than 0.7%, more
preferably less than 0.5%, based on a dry weight of the chemically treated
wood-based cellulosic material in the cellulose-water mixture. A low ash
content can improve quality of the obtained viscosity controlled cellulosic
material and a runnability of the manufacturing process.
A content of fibers having length below 0.6 mm, determined from the
cellulose-water mixture, can be between 10% and 30%, based on the total
content of the chemically treated wood-based cellulosic material fibers. A
curliness of the wood-based cellulosic material, measured from the cellulose-
water mixture before the plasticization step, can be, for example between 7%
and 40%, preferably between 20% and 40%. These values can improve
properties of the obtained viscosity controlled cellulosic material, such as
strength properties of said product.
A sodium (Na) content of the cellulose-water mixture can be at least 200
mg/kg, preferably from 200 mg/kg to 1500 mg/kg based on the dry weight of
the chemically treated wood-based cellulosic material fibers. Thanks to said
sodium content, an efficiency of the manufacturing process can be improved.
If the sodium content is too low, cellulose based fibers are not swollen
enough and chemicals can have difficulties to access. Further, if the sodium
content is too high, pH can be decreased and, hence, chemical consumption
can be increased. Further, water may not penetrate to fiber walls.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
6
The chemically treated wood-based cellulosic material, such as a kraft pulp,
is preferably so called "never dried pulp". Never dried pulp can be easier to
operate than a dried pulp and, further, never dried chemically treated wood-
based cellulosic material can be very cost-effective raw material for the
disclosed manufacturing process.
A WRV of the cellulose-water mixture can be between 1-2 g/g in order to
cause an easy chemical access and, hence, decrease reaction time.
An alpha cellulose content of the chemically treated wood-based cellulosic
material measured before the plasticization step can be at least 65%, more
preferably at least 67%. Further, the alpha cellulose content of the
chemically
treated wood-based cellulosic material measured before the plasticization
step can be less than 99.5%, more preferably 90% at the most. This kind of
alpha cellulose content can have a technical effect by improving a yield and a
material efficiency, causing fast reactions, and working as an internal
activator.
A lignin content of the chemically treated wood-based cellulosic material
measured before the plasticization step can be less than 3%, more preferably
less than 1.0%, and most preferably less than 0.5% based on a dry weight of
the chemically treated wood-based cellulosic material. Low lignin content can
increase brightness of the product.
A softwood content of the chemically treated wood-based material
determined before the plasticization step can be at least 70%, more
preferably at least 85% and most preferably more than 95%, for example
100%, based on a dry weight of the chemically treated wood-based cellulosic
material. Softwood has a lower total hemicellulose content but higher
glucomannan content, hence, it can have a better solubility and faster
reactions than hardwood.
A mixing efficiency during the plasticization step can be between 10 kWh/ADt
and 150 kWh/ADt. More preferably from 15 kWh/ADt to 80 kWh/ADt, and
most preferably from 20 kWh/ADt to 50 kWh/ADt. Technical effect of said
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
7
mixing efficiency is improved, even quality, better solubility and faster
reactions.
During the depressurizing step, i.e., depressurizing step without a steam
explosion, a pressure drop can be slower that 15 bads, more preferably
slower than 10 bads, for example equal or slower than 5 bar/s, and most
preferably equal or slower than 2 bar/s. Thus, a steam explosion can be
avoided and, hence, integrity of fibers can be improved. Typically, the
integrity of fibers improves when the speed of said pressure drop decreases.
The depressurizing step without a steam explosion, wherein the treated
mixture 18 is depressurized, can take at least 1 second, more preferably at
least 3 seconds, and most preferably at least 10 seconds. Furthermore, the
depressurizing step without a steam explosion can take 30 minutes at the
most, more preferably less than 20 minutes, for example 10 minutes at the
most, and most preferably equal or less than 5 minutes. This has a technical
effect of improving the method and maintaining fiber integrity.
In order to depressurize the treated mixture in a controlled manner,
- water, and/or
- a mechanical arrangement
can be used for the substantially slow depressurizing step. Thus, an
uncontrollable way to depressurize the treated mixture, i.e., "a steam
explosion", wherein steam can escape very fast, can be avoided. The
mechanical arrangement for the depressurizing step can comprise, for
example, a chamber and at least one valve, preferably at least one chamber
and at least two valves.
In addition, or alternatively, the mechanical arrangement can have separated
chambers, each chamber having decreased pressure compared to the
previous chamber. In this case, the mechanical arrangement can have, for
example, at least three chambers, such as from 3 to 6 chambers.
Furthermore, there is preferably at least one valve or similar solution
between
two adjacent chambers.
The depressurizing step can comprise the following step:
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
8
- cooling the treated mixture by adding water.
In addition, or alternatively, the depressurizing step can comprise the
following step:
- reducing water vapor mechanically, for example by using
- a screw, and/or
- a chamber with valves, and/or
- compartment valves.
Most preferably, the depressurizing step has the both means, the water and
the mechanical solution.
The method can further comprise the following:
- dosing an activator into the cellulose-water mixture in order to
plasticize the chemically treated wood-based cellulosic material in
the presence of the activator during said plasticization step.
The activator can comprise a filtrate which is obtained from the
plasticization
step. Said filtrate can comprise hydrolysate products from the plasticization
step. The amount of said filtrate can be more than 50%, more preferably
more than 90%, and most preferably at least 99% from the total amount of
the activator. Thanks to this filtrate, total dosage of chemicals added to the
manufacturing process can be decreased, hence, manufacturing costs can
be decreased, and a production efficiency can be increased. Furthermore,
this can be environmentally friendly way to manufacture the viscosity
controlled cellulosic material.
Alternatively, or in addition, the activator can comprise acid solutions,
preferably acid filtrates, from a chemical pulp mill. The amount of said acid
filtrate(s) from the chemical pulp can be at least 30%, more preferably at
least 40%, and most preferably at least 50% calculated from the total amount
of the activator. Hence, manufacturing costs can be decreased, and a
production efficiency can be increased
Alternatively or in addition, the activator can comprise sulfuric acid or
acetic
acid, the total amount of the sulfuric acid and the acetic acid being
preferably
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
9
less than 5%, for example 2% at the most, more preferably less than 1.5%,
for example 1.0% at the most, and most preferably less than 0.5% calculated
from the dry weight of the chemically treated wood-based cellulosic material.
A total usage of added chemicals of the disclosed method, excluding any
circulated filtrate(s) or water(s) from the plasticization step, can be less
than
5%, for example 3% at the most, more preferably less than 2%, for example
1`)/0 at the most, and most preferably less than 0.5%, for example 0.2% at the
most, or exactly 0%, calculated from the dry weight of the chemically treated
wood-based cellulosic material. Therefore, it can be possible to manufacture
the viscosity controlled cellulosic material having a viscosity value in a
range
between 150 ml/g and 500 ml/g in a chemical free, or substantially chemical
free, process. This can have a huge effect on production costs. Further, the
method can be environmentally friendly way to manufacture the viscosity
controlled cellulosic material.
The viscosity value of the viscosity controlled cellulosic material can be at
least 170 ml/g, preferably at least 180 ml/g. Further, the viscosity value of
the
viscosity controlled cellulosic material can be 350 ml/g at the most, more
preferably 300 ml/g at the most, and most preferably 250 ml/g at the most.
This kind of viscosity values can cause improved and faster solubility of the
obtained viscosity controlled cellulosic material.
The obtained viscosity controlled cellulosic material can be washed in a
washing step by using water. Preferably, a temperature of said water used
for the washing step is more than 50 C, for example at least 70 C and most
preferably at least 85 C. Further, advantageously a temperature of said water
is 100 C at the most. Washing step can be used to wash away at least part
of unwanted residues from the viscosity controlled cellulosic material. Thus,
quality of the product can be improved.
Advantageously, at least part of the water used for the washing step is
conveyed to the cellulose-water mixture for increasing temperature of said
cellulose-water mixture.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
Optionally, pH of the obtained viscosity controlled cellulosic material can be
adjusted in a pH adjustment step. Preferably, the target pH value in the pH
adjustment step is between 4 and 9. By using water in the adjusting step, it
may be possible to wash away at least a part of unwanted residues from the
5 viscosity controlled cellulosic material while adjusting the pH value. pH
adjustment may increase the effectiveness of a dissolving step of the
viscosity controlled cellulosic material, which dissolving step may follow the
pH adjusting step.
10 The obtained viscosity controlled cellulosic material can be dried to a
dry
matter content of at least 60%, if needed, for example, for a transportation.
Thanks to the novel process, the obtained viscosity controlled cellulosic
material can have a crystallinity index of at least 74%, more preferably at
least 75%, and most preferably at least 76%.
Due to the novel method, ISO Brightness of the viscosity controlled cellulosic
material manufactured according to claimed method can be at least 70%,
typically between 75 and 90%. Thus, optical properties of the end product
can be improved.
Further, due to the novel method, a length weighted fiber length Lc(I) of the
viscosity controlled cellulosic material measured according to ISO 16065-N
can be at least 0.9 mm, more preferably at least 1.0 mm, and most preferably
at least 1.2 mm. Moreover, a content of fibers having length below 0.6 mm,
measured from the viscosity controlled cellulosic material, can be between 10
and 30%. This kind of fiber contents and lengths can improve the easiness of
the product, i.e., the product can be easier to handle and wash. Further, a
yield can be improved.
An alpha cellulose content of the viscosity controlled cellulosic material can
be at least 67%, preferably at least 69%. Further, the alpha cellulose content
of the viscosity controlled cellulosic material is less than 99.5%, more
preferably 90% at the most. This level of alpha cellulose can improve a
reactivity and a yield due to improved material efficiency. Further, it can
have
an improved environmental impact.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
11
A hemicellulose content of the viscosity controlled cellulosic material can be
at least 0.5% dry wt.%, more preferably at least 3 dry wt.%, for example
between 3 dry wt.% and 10 dry wt.%. This kind of hemicellulose content can
improve a reactivity and, further, a yield due to improved material
efficiency.
Further, it can have an improved environmental impact.
Thanks to the novel method, R18 solubility of the viscosity controlled
cellulosic material can be at least 60%, more preferably at least 70%.
Further, R18 solubility of the viscosity controlled cellulosic material can be
87% at the most, more preferably 84% at the most, for example between
70% and 84%. R18 solubility describes a solubility of the material when
measured by using 18% NaOH solution. A value of R18 solubility discloses
an insoluble part of the material. Thanks to said R18 solubility of the
material,
the obtained viscosity controlled cellulosic material can have very good
solubility. Thus, the production efficiency of the regenerated cellulose
material, which can be manufactured from the viscosity controlled cellulosic
material, can be improved.
A sodium (Na) content of the viscosity controlled cellulosic material can be
at
least 200 mg/kg, for example between 200 mg/kg and 1500 mg/kg based on
the dry weight of the chemically treated wood-based cellulosic material fibers
Said sodium content has an effect, for example, on a solubility of the
obtained viscosity controlled cellulosic material by improving the solubility
rate of the material. Furthermore, a viscosity can be improved.
A curliness of the viscosity controlled cellulosic material can be at least
25%,
more preferably at least 30%, such as at least 35%, and most preferably at
least 40%. Furthermore, the curliness of the viscosity controlled cellulosic
material can be 90% at the most, for example less than 85% or equal or less
than 80%. The curliness has an effect on a strength of the end-product as
well as water remove properties of the product.
A Water Retention Value (WRV) of the viscosity controlled cellulosic material
can be between 1 g/g and 2 g/g. This can cause an easier chemical access
and, hence, a faster reaction.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
12
A lignin content of the viscosity controlled cellulosic material can be less
than
1.5%, more preferably less than 1%, and most preferably less than 0.5%.
This kind of very low lignin content can increase brightness of the product,
the effect on the brightness increase as the lignin content decreases.
An extractive content of the viscosity controlled cellulosic material can be
less than 0.2%, more preferably less than 0.1%. This kind of low extractive
content can increase quality of the product.
The chemically treated wood-based cellulosic material can comprise
bleached Kraft pulp and/or bleached sulfite pulp and/or bleached soda pulp.
The chemically treated wood-based cellulosic material can refer to bleached
Kraft pulp and/or bleached sulfite pulp and/or bleached soda pulp. Most
preferably, the chemically treated wood-based cellulosic material refers to
the
kraft pulp.
This invention does not relate to a viscose, which can be manufactured from
dissolving pulp. The viscose is an example of a different kind of cellulosic
material obtained from a different kind of raw material by using a different
kind of process. Viscose manufacturing is generally an environmentally
problematic and a slow process. The claimed novel method can be
environmentally friendly solution to treat wood-based cellulosic material in
order to obtain the viscosity controlled cellulosic material having the
specific
viscosity value.
Due to the claimed method, the viscosity controlled cellulosic material may
be manufactured by using moderate price materials instead of expensive
organic solvents and, moreover, without need of handling toxic products.
Thanks to the novel solution, the product may also be used as a raw material
for cosmetic or food packaging products.
A yield of a manufacturing process depends on raw materials and conditions
of the process, such as a usage of chemicals, a temperature, a dry matter
content, a pH level, and a duration of the plasticization step. By using the
novel manufacturing process, a yield of the process may be substantially
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
13
increased. For example, it can be possible to adjust hemicellulose content of
the manufactured product, not simply remove substantially all hemicelluloses.
The novel process can be substantially simple. Further, the novel process
can be easy to handle. The novel manufacturing process can also be
environmentally friendly. With the novel process, it can be possible to
consume very small quantity of chemicals. Further, it can be possible to
obtain the viscosity controlled cellulosic material without further dosed
chemicals e.g. after kraft pulping by using chemically treated cellulose based
raw material, such as kraft pulp.
The product obtained from the claimed process, i.e., the viscosity controlled
cellulosic material, is typically cold alkali soluble. The manufactured
viscosity
controlled cellulosic material can be modified to produce some different kind
of end products. Typically, no additional chemical treatment is needed to
dissolve the viscosity controlled cellulosic material. Thus, the viscosity
controlled cellulosic material may be more economical than other cellulosic
materials processed with known methods.
Further, thanks to the novel process, the novel viscosity controlled
cellulosic
material product can be manufactured in a continuous process having a good
production efficiency.
Brief description of the drawings
In the following, the invention will be illustrated by drawings in which
Figs 1-3 show schematically some example steps,
Figs 4a-c show some photos from experimental tests,
Figs 5a-c show some microscopy images from experimental tests, and
Figs 6a-11 show test results from experimental tests.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
14
Detailed description
In the following disclosure, all percentages are by weight, if not indicated
otherwise. All percentages relating to cellulosic material(s) are by dry
weight,
if not indicated otherwise.
All embodiments in this application are presented as illustrative examples,
and they should not be considered limiting.
Unless otherwise stated, the following standards (valid on 01/2019) and
measuring methods refer to methods which can be used to obtain stated
values of parameters:
- R18 solubility: T 235 cm-00
- Consistency: ISO 638 (dry mater content)
- Curliness [%]: ISO 16065-N
- Ash content [%]: Mod ISO 2144
- Lignin content [A]: KCI 115 b82
- Extractive content [A]: mod. ISO 14453
- Softwood and/or hardwood can be analyzed with a microscopic
method by using a microscopy.
- WRV (g/g) is measured according to ISO 23714:2014, which
specifies a procedure for the determination of the water retention
value (WRV) of all kinds of pulp.
- Brightness [% ISO]: ISO 2470-1
- Alfa-cellulose content [%] can be determined by using R18 solubility
measurements,
- Hemicelluloses content [%] can be determined by measuring a total
sugar content of a sample according to a standard SCAN-CM 71:09
and determine a hemicellulose content from the total sugar content.
- Glucose content [%] from the total sugar content can be determined
by using the standard SCAN-CM 71:09 for total sugar content and
determine glucose content from said total sugar content.
- Fiber properties are measured according to standard ISO 16065-
2:2014 by using Valmet Fiber Image Analyzer (Valmet F55). A
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
weight of a sample should be at least 0.1 g, for example between 0.1
g - 0.2 g for hardwood samples and at least 0.3 g, for example
between 0.3 - 0.5 g, for softwood samples. ISO 16065-2:2014
specifies a method for determining fibre length by automated optical
5 analysis using unpoiarized light. The method is applicable to all
kinds
of pulp. However, fibrous particles shorter than 0.2 mm are not
regarded as fibres for the purposes of ISO 16065-2:2014 and,
therefore, are not included in the results.
Sodium content of the raw material [mg/kg of dry pulp] and Sodium
10 content of the viscosity controlled cellulosic material [mg/kg of dry
material]: SFS-EN ISO 11885, by using an ICP analyzer.
Viscosity [ml/g] is measured according to ISO 5351:2010. It relates to
a determination of limiting viscosity number in cupri-ethylenediamine
(OED) solution. ISO 5351:2010 specifies a method which yields a
15 number that is an estimate of the limiting viscosity number of pulp in
a dilute cupri-ethylenediamine (OED) solution.
Crystallinity index [%] is measured according the following method
(RISE, Research of Sweden):
WAXS (Wide Angle X-ray Scattering) measurements were performed
on an Anton Paar SAXSpoint 2.0 system (Anton Paar, Graz, Austria)
equipped with a Microsource X-ray source (Cu Ka radiation,
wavelength 0.15418 nm) and a Dectris 2D CMOS Eiger R 1M
detector with 75 mm by 75 mm pixel size. All measurements were
performed with a beam size of approximately 500 mm diameter, at a
sample stage temperature of 25 C (temperature control was
employed) with a beam path pressure at about 1-2 mBar. The
sample to detector distance (SDD) was 111 mm during
measurements. All samples were mounted on a Multi-Solid-Sample
Holder (Anton Paar, Graz, Austria). The Sampler was then mounted
on a VarioStage (Anton Paar, Graz, Austria). The samples were
exposed to vacuum during measurement. For each sample 6 frames
each of 6 minutes duration were read from the detector, giving a total
measurement time of 36 minutes per sample. For all samples the
transmittance was determined and used for scaling of intensities. The
software used for instrument control was SAXSdrive version
2.01.224 (Anton Paar, Graz, Austria), and post-acquisition data
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
16
processing was performed using the software SAXSanalysis version
3.00.042 (Anton Paar, Graz, Austria). Crystallinity indexes (Cr!) of the
samples were determined according to the Segal signal height
method (Segal et al. 1959), ref. Segal, L, Creely, J.J., Martin Jr., A.E.
and Condrad, C.M. (1959) An Empirical Method for Estimating the
Degree of Crystallinity of Native Cellulose Using the X-Ray
Diffractometer. Textile Research Journal, 29, 786-794.
- Molar Mass Distribution (MMD) is measured according to the
following method:
The molar mass distributions (MMD) of the cellulose derivatives
were
determined by size exclusion chromatography (SEC)
using
tetrahydrofuran (THF) as the mobile phase. The SEC
system consists of a guard column, PLgel 10 pm Guard 50 x 7.5
mm, and three PLgel 10 pm
MIXED-B LS 300 x 7.5 mm
columns connected in series. The detection was performed
using a refractive index detector (Waters 410).
The samples
were dissolved in THF (approx. 1.5 mg/ml) and filtered (PTFE
syringe filter 0.2 pm) The samples were not completely dissolved
in THF. Duplicate samples were analyzed. Calibration was
performed using polystyrene standards with molecular weights from
3000 to 7 270 000. The calibration points were fitted to a linear
function. MMD, peak molar weight (Mp), weight average molar
weight (Mw),
number average molar weight (Me) and
polydispersity (PD) index
(Mw/Me) were calculated using Cirrus
GPC software version 3.1 by Polymer laboratories (Agilent).
Values, which are measured/determined from the cellulose-water mixture 15
and/or chemically treated wood-based cellulosic material 10, are values
which are determined before the plasticization step 100.
Values, which are measured/determined from the viscosity controlled
cellulosic material, are values which are determined after the plasticization
step 100.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
17
The following reference numbers are used in this application:
chemically treated wood-based cellulosic material,
cellulose-water mixture,
5 18 treated mixture,
viscosity controlled cellulosic material,
dissolved viscosity controlled cellulosic material,
regenerated cellulose material,
90 pretreating step comprising, for example, a pulper,
10 95 forming the cellulose-water mixture 15,
96 means for forming the cellulose-water mixture 15,
100 plasticization step,
101 continuous reactor,
102 filtrate obtained from the plasticization step,
15 .. 105 depressurizing step,
110 washing step comprising, for example, a wash press,
120 drying step,
121 drying device,
130 dissolving step of the viscosity controlled cellulosic material, and
20 140 further processing of the dissolved viscosity controlled cellulosic
material.
Natural cellulose is a linear compound with a simple chemical functionality
having 3 hydroxyl groups for a glucose unit.
In this application, the term "chemically treated wood-based cellulosic
material 10" refers to kraft pulps, sulfite pulps and soda pulps, which may
contain any wood-based cellulose material, i.e., the chemically treated wood-
based cellulosic material 10 can originate from any wood material(s).
Furthermore, the term "chemically treated wood-based cellulosic material 10"
refers to a material that does not comprise dissolving pulp. The term
"dissolving pulp" refers to so called dissolving pulp, which is a bleached
pulp
that has cellulose content more than 90 wt.-% and particularly low
hemicellulose content. The dissolving pulp can be dissolved in a specific
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
18
solvent. However, a yield and production efficiency of the manufacturing
process may not be as good as with the kraft pulp, soda pulp or sulfite pulp.
Furthermore, the term "chemically treated wood-based cellulosic material 10"
refers to material that does not comprise mechanical pulp. The term
"mechanical pulp" refers to cellulose fibers, which are isolated from any
wood-based cellulosic material by a mechanical pulping process. Preferably,
the viscosity controlled cellulosic material 20 does not comprise the
mechanical pulp.
The kraft pulp, soda pulp and/or sulfite pulp can be dried and/or never-dried
pulp(s) and they can be pre-treated chemically, physically or enzymatically to
enhance the effect of the plasticization. The never-dried pulp can be easier
to
operate, and the usage of the never-dried pulp can decrease manufacturing
costs of the obtained viscosity controlled cellulosic material, hence,
preferably the pulp(s) comprise or consist of the never-died pulp(s).
In this application, the term "viscosity controlled cellulosic material 20"
refers
to a material which is obtainable from the chemically treated wood-based
cellulosic material 10 by using a plasticization step and a depressurizing
step. The viscosity controlled cellulosic material is typically cold alkali
soluble.
The term "cold alkali soluble" refers to a cold alkali soluble, plasticized
cellulose material, i.e., the viscosity controlled cellulosic material, which
is
dissolvable to an aqueous alkaline having NaOH content of solution between
5% and 10%, for example from 7% to 8%, at a temperature from -3 C to
-12 C, for example at a temperature from -5 C to -8 C.
The term "R18 solubility" refers to a solubility without carbon sulfide
treatment. R18 solubility is measured according to standard T 235 cm-00.
The term "steam explosion" refers to a method wherein a pressure is caused
by over-heated water and a pressure drop is faster than 15 bar/s. This kind of
fast pressure release can cause significant fiber structure changes.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
19
Preferably, an amount of non-wood material in the viscosity controlled
cellulosic material is less than 20%, more preferably less than 10% and most
preferably less than 5%, for example 2% at the most, calculated from the dry
weight of the viscosity controlled cellulosic material. In an advantageous
embodiment, the viscosity controlled cellulosic material does not comprise
non-wood material at all. Non-wood material can be agricultural residues,
grasses or other plant substances such as straw, coconut, leaves, bark,
seeds, hulls, flowers, vegetables or fruits from cotton, corn, wheat, oat,
rye,
barley, rice, flax, hemp, manila hemp, sisal hemp, jute, ramie, kenaf,
bagasse, bamboo, or reed.
The chemically treated wood-based cellulosic material can be obtained from
softwood trees, such as spruce, pine, fir, larch, douglas-fir or hemlock, or
hardwood trees, such as birch, aspen, poplar, alder, eucalyptus, or acacia, or
.. a mixture of softwoods and/or hardwoods.
An effect of the plasticization step 100 typically depends on raw material(s),
such as wood species used in the treatment. Thus, preferably the chemically
treated wood-based cellulosic material comprises or consists of eucalyptus,
birch, spruce and/or pine, the total amount of those wood species being
preferably more than 70%, more preferably at least 80% and most preferably
at least 90 % calculated from the total amount of the chemically treated
wood-based cellulosic material. This can improve the properties of the
obtained product.
A softwood content of the chemically treated wood-based material measured
from the cellulose-water mixture 15 is preferably more than 30%, for example
at least 50%, more preferably at least 70% and most preferably at least 90%
based on a dry weight of the chemically treated wood-based cellulosic
material 10. The usage of the softwood has an effect on hemicellulose
content. Softwood has higher glucomannan content. Further, softwood can
have a better solubility and lower reaction time. Therefore, a production
efficiency can be improved.
Most advantageously, the chemically treated wood-based cellulosic material
comprises at least 50%, more preferably at least 70% and most preferably at
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
least 90% softwood kraft pulp, calculated from the dry weight of the
chemically treated wood-based cellulosic material, which has
- fibers having a length over 2 mm,
- lignin content between 0 and 3%,
5 - hemicellulose content between 0.5 and 33%, and
wherein, advantageously, over 70 (:)/0 of fibers has a fiber length more than
0.2 mm and a width between 10-50 micrometer, when measured with
standard ISO 16065-2:2014 by using Valmet Fiber Image Analyzer (Valmet
FS5). By using this kind of material, properties and quality of the
10 manufactured product can be improved.
An alpha cellulose content of the chemically treated wood-based cellulosic
material 10 measured before the plasticization step 100 is preferably at least
65%, more preferably at least 67%. Further, the alpha cellulose content of
15 the chemically treated wood-based cellulosic material 10 measured before
the plasticization step 100 is preferably less than 99.5%, more preferably
equal or less than 95% and most preferably equal or less than 90%. Thanks
to said alpha cellulose content of the raw material, i.e., the chemically
treated
wood-based cellulosic material 10, a high yield, i.e., a high material
20 efficiency, can be obtained. Further, the method can have a short
treatment
time (due to faster reactions).
The chemically treated wood-based cellulosic material 10 contains cellulose
material which can contain hemicelluloses. Typically, lignin and wood
extractives have been removed at least mostly.
The chemically treated wood-based cellulosic material 10 can comprise
cellulose fibers, which are isolated from cellulose material by a chemical
pulping process. Therefore, lignin is at least mostly removed from the
material. The chemically treated wood-based cellulosic material 10 can be
unbleached or bleached. Preferably, the chemically treated wood-based
cellulosic material 10 is bleached.
Natural pulp fibers can be very difficult to process with chemicals due to
high
crystallinity of preventing the chemicals from penetrating fiber surfaces.
Thanks to the novel method disclosed in this application, it can be possible
to
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
21
produce cellulose based products with improved safety of workers. For
example, highly toxic carbon disulphide that is used in the production of
viscose, can be replaced with more safety raw material.
The chemically treated wood-based cellulosic material 10 is preferably kraft
pulp, and/or sulphite pulp, and/or soda pulp in order to obtain viscosity
controlled cellulosic material 20 having good properties. Further, by using
these materials, the viscosity controlled cellulosic material can be
manufactured in an environmentally friendly way. Thus, chemically treated
wood-based cellulosic material 10 can comprise at least 70 wt.-% or at least
80% wt.-%, more preferably at least 90 wt.-% or at least 95 wt.-%, and most
preferably at least 98 wt.-% or exactly 100 wt.-% bleached kraft pulp, and/or
sulfite pulp and/or soda pulp, based on the dry weight of the chemically
treated wood-based cellulosic material 10. These raw materials can have the
following advantages:
- high yield, and
- accelerated reactions during the plasticization step 100 into wanted
area of viscosity due to hemicelluloses which tends to degrade into
acid.
Most advantageously, the chemically treated wood-based cellulosic material
10 comprises kraft pulp, preferably bleached kraft pulp. The amount of
bleached kraft pulp is preferably at least 50 w-%, more preferably at least 80
w-% and most preferably at least 90 wt.-%, such as 100 wt.-%, calculated
from the total dry weight of the chemically treated wood-based cellulosic
material 10. The bleached kraft pulp is an economical raw material with
suitable properties for this novel method. Further, the usage of the kraft
pulp
can improve the properties of the obtained viscosity controlled cellulosic
material. Furthermore, the kraft pulp can be environmentally friendly raw
material. Therefore, a yield and quality of the obtained product as well as
production efficiency of the manufacturing process can be increased.
A lignin content of the chemically treated wood-based cellulosic material 10
is
preferably less than 3%, more preferably less than 1.0%, and most preferably
less than 0.5% based on the dry weight of the chemically treated wood-
based cellulosic material. Therefore, the lignin, which could be harmful for
the
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
22
process, is not decreasing the efficiency of the method. Further, a very low
lignin content can increase a brightness value of the obtained product.
The chemically treated wood-based cellulosic material 10 can be pretreated
for better manufacturing efficiency. Thus, the chemically treated wood-based
cellulosic material 10 can have at least one pretreating step 90 in order to
pretreat the chemically treated wood-based cellulosic material 10 before the
plasticization step 100.
The pretreatment step 90 can comprise, for example, a refining step. The
refining step of the chemically treated wood-based cellulosic material 10 can
be carried out with a device capable of separating and/or making the
cellulose fibers shorter. The prerefiner device can be a refiner, such as a
hammer mill, a fluffing machine, a rotary cutter, a conical refiner, or a disk
refiner.
In an embodiment, due to the increased costs and, further, an effect of the
refining for the properties of the manufactured product, the chemically
treated
wood-based cellulosic material 10 is preferably an unrefined pulp.
The amount of mechanical energy used in refining correlates with the water
drainage resistance, which may be measured by the Schopper Riegler (SR)
Freeness test. The Schopper Riegler (SR) Freeness test provides an
empirical measurement value of the drainage resistance of a pulp slurry. The
Schopper Riegler (SR) Freeness value may be determined using a SCAN-C
19:65 test method. The chemically treated wood-based cellulosic material 10,
such as Kraft pulp, preferably has Schopper Riegler (SR) Freeness 35 at the
most, more preferably 30 at the most, for example between 12 and 20,
measured before the plasticization step.
The pretreatment step 90 can comprise a dosage of a chemical, such as an
acid. The pretreatment step can comprise, for example, a dosage of acetic
acid. The pretreatment step comprising the dosage of an acid can decrease
a time needed for the plasticization step 100. However, the addition of the
chemical, such as the acid, can increase the manufacturing costs of the
manufactured product. However, due to the decreased duration of the
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
23
plasticization step 100, the production efficiency can be improved despite of
the increased chemical costs.
Due to the novel process, properties of the obtained viscosity controlled
cellulosic material can be improved. Thus, properties of a regenerated
cellulose material 40 which may be obtained from the viscosity controlled
cellulosic material 20, can also be improved. Further, because no dissolving
pulp is needed as raw material, raw material costs may be decreased.
Hemicellulose content of the chemically treated wood-based cellulosic
material 10 can be between 0 and 33 wt.-%. Hemicellulose content of the
chemically treated wood-based cellulosic material 10 is preferably at least
0.5
wt.-%, more preferably at least 3 wt.-%, or at least 5 wt.-%, and most
preferably at least 10 wt.-%. Further, hemicellulose content of the chemically
treated wood-based cellulosic material 10 is preferably 33 wt.-% at the most,
more preferably 20 wt.-% at the most, and most preferably 15 wt.-% at the
most. Higher hemicellulose content can be used to increase yield and to
achieve higher material efficiency. Further, hemicellulose can be used as
internal activator, improving reactions and decreasing a dosage of other
chemicals.
The chemically treated wood-based cellulosic material 10 can be treated in a
continuous process to form the viscosity controlled cellulosic material 20.
Thanks to the novel continuous process, a production capacity can be
increased, and production costs decreased and, hence, a production
efficiency can be improved. Surprisingly, also brightness of the continuously
manufactured product was improved comparing to a product obtained from a
batch process.
The method for manufacturing viscosity controlled cellulosic material 20
having a viscosity value in a range between 150 ml/g and 500 ml/g in a
continuous process can comprise the following steps:
i) forming a cellulose-water mixture 15 comprising the chemically
treated wood-based cellulosic material, the cellulose-water mixture
having a dry matter content between 3% and 20%,
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
24
ii) treating the formed cellulose-water mixture 15 in a plasticization
step
100 at a temperature between 130 C and 200 C and preferably at a
pressure between 3 and 15 bar, more preferably between 5 and 10
bar, at least 5 minutes and 120 minutes at the most, while mixing the
cellulose-water mixture 15, and feeding hot water and/or water steam
to the cellulose-water mixture, thereby obtaining a treated mixture 18,
and
iii) depressurizing the treated mixture 18 after the plasticization step
100
in a depressurizing step 105 in a controlled manner without a steam
explosion, to maintain fiber integrity, thereby obtaining the viscosity
controlled cellulosic material.
The step ii) wherein the cellulose-water mixture is treated in the
plasticization
step 100 in the presence of hot water and/or water steam can activate fibres.
A polydispersity of the obtained viscosity controlled cellulosic material can
be
less than 10, for example 8 at the most, more preferably less than 7, and
most preferably less than 6, for example 5 at the most. Further, the
polydispersity can be at least 1. Thanks to the novel, continuous process, the
polydispersity of the viscosity controlled cellulosic material 20 can be
improved, i.e. the polydispersity value can be smaller than conventionally.
Therefore, properties and a solubility of the viscosity controlled cellulosic
material 20 can also be improved.
A system for producing viscosity controlled cellulosic material having a
viscosity value in a range between 150 ml/g and 500 ml/g in a continuous
process can comprise the following:
- means for forming a cellulose-water mixture and/or feeding the
cellulose-water mixture to a continuous reactor,
- a continuous reactor, such as a continuous kneader reactor, for
treating the cellulose-water mixture in a plasticization step 100 at a
pressure between 5 bars and 10 bars,
- mixing means, such as a mixing device, for mixing the cellulose-
water mixture during the plasticization step,
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
- heating means for increasing temperature of the cellulose-water
mixture in the continuous reactor, such as a feeder to feed water
steam to the continuous reactor, and
- means for depressurizing the treated mixture 18 in a controlled
5 manner without a steam explosion after the plasticization step 100,
such as a feeder to feed water to the treated mixture.
Further, the system for producing viscosity controlled cellulosic material
having a viscosity value in a range between 150 ml/g and 500 ml/g in a
10 continuous process can also comprise the following means:
- washing device, such as a wash press, for washing the obtained
viscosity controlled cellulosic material, and/or
- pH adjusting means, such as means for adding water and/or dosing
chemical(s) and/or
15 - a dryer for drying the obtained viscosity controlled cellulosic
material.
The chemically treated wood-based cellulosic material can have a viscosity
value between 400 ml/g and 1200 ml/g, determined from the cellulose-water
mixture 15 before the plasticization step. The viscosity value of the
20 chemically treated wood-based cellulosic material is preferably at least
400
ml/g, more preferably at least 450 ml/g, and most preferably at least 500
ml/g, determined from the cellulose-water mixture 15 before the plasticization
step. Further, the viscosity value of the chemically treated wood-based
cellulosic material is preferably 1200 ml/g at the most, more preferably 1000
25 ml/g at the most, and most preferably 900 ml/g at the most, determined
from
the cellulose-water mixture 15 before the plasticization step. The technical
effect of said viscosity value is that the reaction can be improved, i.e., the
reaction time during the plasticization step can be decreased. Further,
typically, the alkali solubility of the viscosity controlled cellulosic
material
improves when the viscosity decreases. However, too low viscosity can
cause several problems to the end product, for example an average fibre
length and a brightness of the end product can be decreased and, moreover,
a yield can also be decreased.
ISO Brightness of the chemically treated wood-based cellulosic material 15,
determined before the plasticization step, is preferably at least 70%, more
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
26
preferably at least 86%. Thus, the obtained viscosity controlled cellulosic
material can have desired optical properties. Further, chemical consumption
of the process may be decreased if brightness of the raw material is high
enough. Thus, the chemically treated wood-based cellulosic material
preferably consists of bleached pulp(s).
Further, an extractive content of the chemically treated wood-based cellulosic
material 15, determined before the plasticization step, is preferably less
than
0.4% and more preferably less than 0.2%, based on a dry weight of the
chemically treated wood-based cellulosic material. The quality of the
obtained viscosity controlled cellulosic material can be improved and
runnability of the end-product can be increased if the extractive content is
small enough.
An ash content of the chemically treated wood-based cellulosic material 10
measured from the cellulose-water mixture is preferably less than 0.7%,
more preferably less than 0.5%, based on a dry weight of the chemically
treated wood-based cellulosic material. The technical effect of the low ash
content is that a quality of the viscosity controlled cellulosic material and
run nability of the process can be improved.
A content of fibers having length below 0.6 mm, determined from the fibers of
the cellulose-water mixture 15, is preferably between 10% and 30%, based
on the total content of the chemically treated wood-based cellulosic material
fibers.
A curliness of the chemically treated wood-based cellulosic material 10
determined from the cellulose-water mixture 15 before the plasticization step
is preferably between 7% and 40%, more preferably between 20% and 40%.
This has a technical effect of improving strength properties of the obtained
product.
A sodium (Na) content of the cellulose-water mixture 15 is preferably at least
200 mg/kg, for example from 200 mg/kg to 1500 mg/kg based on the dry
.. weight of the chemically treated wood-based cellulosic material fibers. If
the
sodium content is too low, fibers may not be swollen enough, hence,
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
27
chemicals may have difficulties to access to the fibers. Further, if the
sodium
content is too high, consumption of chemicals may be increased, and water
may not penetrate fiber walls as efficiently as with the optimum sodium
content.
The chemically treated wood-based cellulosic material 10 can have a
crystallinity index between 50% and 70%. Said crystallinity index can improve
chemical access into fibres of the chemically treated wood-based cellulosic
material.
A WRV of the cellulose-water mixture 15 is preferably between 1 g/g and 2
g/g. This WRV rate can improve chemical access and, hence, decrease the
reaction time.
At least one acid is preferably used as an activator to accelerate a viscosity
adjustment during the plasticization step 100. The activator can be dosed
before the plasticization step 100 and/or in the beginning of the
plasticization
step. Thus, the method can comprise the following step:
- dosing an activator into the cellulose-water mixture 15 in order
to
hydrolyse the chemically treated wood-based cellulosic material 10 in
the presence of the activator during the plasticization step 100.
Advantageously, the activator comprises a filtrate 102 from the plasticization
step 100. The acids from wood can release protons during plasticization step
100, thus, mild acidic conditions may be created without chemicals. However,
this is typically not enough for the needed acidic conditions. Thanks to the
novel method, part of this acid solution can be separated and conveyed as
filtrate(s) 102 and used again in the plasticization step 100, hence, improved
acidic conditions can be obtained without any addition of chemicals (see Fig.
1b).
Therefore, the activator can comprise filtrate(s) 102, which are obtained from
the plasticization step 100. The filtrate(s) 102 are typically reaction
filtrate(s)
which comprise hydrolysate products from the plasticization step 100. Said
filtrate(s) 102 typically contains carboxylic acid, hence, they can be used to
improve the reaction efficiency during the plasticization step 100. Therefore,
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
28
the activator comprising the filtrate(s) 102 can be used to obtain the
suitable
acidic conditions to obtain the predetermined viscosity adjustment during the
plasticization step 100.
The total amount of said filtrate(s) 102, obtained from the plasticization
step
100, can be more than 50%, such as at least 80%, more preferably more
than 90%, such as at least 95%, and most preferably at least 99% or exactly
100% calculated from the total amount of the activator. This can be very cost-
effective solution for the activator. Therefore, a production efficiency of
the
novel method can be increased. Further, said filtrate 102 separated from the
plasticization step 100 and circulated to the plasticization step 100, e.g. to
the
continuous reactor 101, can be very environmentally friendly solution.
In addition, or alternatively, the activator may comprise acid solutions,
preferably acid filtrates, such as acid bleaching filtrates from a chemical
pulp
mill.
If the activator comprises added chemicals, such as added acid(s), and not
only said filtrates, the added acid(s) preferably comprise acetic acid and/or
sulfuric acid. In this case, the added chemicals preferably comprise at least
80 wt.-%, more preferably at least 90 wt.-%, and most preferably at least 97
wt.% acetic acid and/or sulfuric acid. Advantageously, the added chemicals
comprise or consist of acetic acid. The amount of acetic acid can be at least
80 wt.-%, more preferably at least 90 wt.-%, and most preferably at least 97
wt.% calculated from the total weight of the added chemicals for the
plasticization process. Acetic acid has good properties for the activator, and
it
is quite cost-effective chemical, hence, it is possible to reduce
manufacturing
costs and increase production efficiency by using the acetic acid for the
viscosity adjustment.
If the activator comprises sulfuric acid and/or acetic acid, the total amount
of
the sulfuric acid and the acetic acid can be less than 5%, for example 3% at
the most, more preferably less than 2%, for example 1.5% at the and most
preferably less than 1%, for example 0.5% at the most, calculated from the
dry weight of the chemically treated wood-based cellulosic material. Thus,
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
29
thanks to the novel environmentally friendly solution, only small quantity of
acid, if any, can be used.
Acids from the filtrate(s) 102 can be separated by e.g. distillation and/or at
least part of the filtrate(s) 102 is circulated into the plasticization step
100
without the separation stage. Advantageously, to obtain improved production
efficiency, the filtrate(s) 102 or at least a part of the filtrate(s) 102 is
circulated
into the plasticization step 100 as such. Typically, these filtrate(s) 102
obtained from the plasticization step, contains carboxylic acids formed from
the wood-based cellulosic material during the plasticization step 100.
The only chemical used in the method can be the filtrate 102 obtained from
the plasticization step 100. Therefore, thanks to the novel method, the
viscosity controlled cellulosic material can be manufactured from the
chemically treated wood-based cellulosic material 10 without chemicals.
Therefore, this novel method can be chemical free.
Advantageously, total dosage of chemicals added to the system during the
following steps:
i) forming a cellulose-water mixture,
ii) treating the formed cellulose-water mixture 15 in a plasticization
step,
and
ii) depressurizing the treated mixture 18 after the plasticization
step 100
in a depressurizing step 105, is less than 5%, for example 3 (:)/0 at the
most, more preferably less than 2%, for example 1%, and most
preferably less than 0.5%, such as exactly 0%, calculated from the
dry weight of the chemically treated wood-based cellulosic material
10.
Therefore, thanks to this novel method, the viscosity controlled cellulosic
material 20 can be manufactured in an environmentally friendly way, and still
have a high yield and an improved production efficiency.
Preferably, the plasticization step 100 does not contain enzymes due to their
expensiveness and difficultness in use. Furthermore, the enzymes may not
work within conditions of the plasticization step 100. Thus, if any enzymes
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
are used, they are preferably dosed before the plasticization step 100, hence,
the enzyme(s) will be destroyed during the plasticization step. Thus, any
allergy reactions of end users, as well as other problems caused by the
enzymes, can be avoided. A total dosage of the enzyme(s) is preferably less
5 than 0.5%, more preferably less than 0.1%, and most preferably exactly
0%,
calculated from the dry weight of the chemically treated wood-based
cellulosic material 10.
The step i), i.e., forming the cellulose-water mixture 15, can be implemented
10 by any means known to a man skilled in the art.
The plasticization step 100 can be carried out in a continuous reactor 101.
Thus, the plasticization step 100 preferably comprises the following steps:
- feeding the cellulose-water mixture 15 to the continuous reactor 101,
15 and
- treating the formed cellulose-water mixture 15 continuously in the
reactor 101, thereby obtaining a treated mixture 18.
Thus, the means for treating the cellulose-water mixture 15 during the
20 plasticization step preferably comprises the continuous reactor 101.
Advantageously, the raw material is conveyed horizontally, or at least
substantially horizontally, during the plasticization step 100. This can
improve
an effect of mixing and, hence, increase a reaction efficiency. Thus, a
25 production efficiency can be improved. Preferably, an angle between a
horizontal line and a length direction of the continuous reactor 101 can be
less than 20 .
The heating means in a plasticization step 100 can comprise a feeding
30 device for feeding water steam and/or hot water to the continuous reactor
101 in order to increase temperature of the reactor 101.
The mixing means for mixing the cellulose-water mixture 15 during the
plasticization step can comprise, for example, a mixing device. The mixing
means can comprise, for example, an extruder. Advantageously, the mixing
means for mixing the cellulose-water mixture 15 can comprise, for example,
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
31
a continuous kneader reactor (i.e., a kneader type of a reactor), or another
kind of continuous screw reactor, which is configured to mix the cellulose-
water mixture during the plasticization step 100. Thanks to the mixing during
the plasticization step 100, a reaction efficiency during the plasticization
step
can be hugely improved, hence, production time and energy needed for the
plasticization step can be decreased. Furthermore, properties of the
manufactured product, such as a polydispersity and a brightness of the
viscosity controlled cellulosic material 20, can be improved.
Preferably, a mixing efficiency during the plasticization step is between 10
kWh/ADt and 150 kWh/ADt. More preferably, the mixing efficiency during the
plasticization step is at least 15 kWh/ADt, and most preferably at least 20
kWh/ADt. Furthermore, the mixing efficiency during the plasticization step is
more preferably equal or less than 80 kWh/ADt, and most preferably equal or
less than 50 kWh/ADt. Technical effect of said mixing efficiency is even
quality, better solubility and faster reactions. Thus, reaction time can be
decreased, hence, production efficiency can be improved.
The continuous reactor can have several segments, wherein each segment
forms a chamber, hence, there may not be too much of exchange of
materials between neighboring chambers over the length of the continuous
reactor.
Advantageously, the plasticization step 100 is implemented by treating the
formed cellulose-water mixture 15 in a continuous horizontal reactor. The
cellulose-water mixture 15 can be efficiently conveyed over the length of the
continuous horizontal reactor, such as a continuous horizontal screw reactor.
Most preferably, the continuous horizontal reactor is a kneader reactor.
Therefore, there may not be any or almost any exchange of material between
neighboring parts over the length of the continuous horizontal reactor. Thus,
the manufacturing process can be easily controlled. Therefore, it is possible
to have a mild treatment, which may improve properties of the manufactured
product.
The continuous reactor 101, such as a screw reactor, can have valves,
wherein the valves are opened at different times to prevent the material in
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
32
different chambers to be mixed and, hence, the valves can be used to control
the conveying process of the material during the plasticization step 100.
In an embodiment, a screw reactor, if used, does not have very high pressing
effect on the wood-based cellulosic material during the plasticization step
100
in order to avoid many fibre bundles affecting the properties of the
manufactured product.
The system can further comprise means for dosing the activator to the
cellulose-water mixture 15 in order to treat the cellulose-water mixture in
the
presence of the activator in the plasticization step 100.
At least part of the filtrate 102 obtained from the plasticization step 100
can
be conveyed from at least one of the chambers of the continuous reactor 101
and/or after the continuous reactor 101 to another chamber of said
continuous reactor 101 and/or before the first chamber of the continuous
reactor 101. Hence, at least part of the acid filtrate 102 can be separated
and
conveyed as acid filtrate and used again in the plasticization step 100.
Therefore, improved acidic conditions can be obtained without any addition of
chemicals when, for example, the continuous reactor 101 has chambers.
The means for dosing the activator to the cellulose-water mixture can
comprise means for conveying filtrate 102 obtained from the second part
100b of the continuous reactor 101 and/or after the continuous reactor 101 to
the first part 100a of the continuous reactor 101 and/or before the continuous
reactor 101. The second part 100b of the continuous reactor 101 is located
forward from the first part 100b of the continuous reactor 101. This is
illustrated in Fig lb.
Temperature of the plasticization step 100 can be increased and/or controlled
with
- water steam,
- hot water,
- electricity (with electrical resistance),
- gas, and/or
- fuel oil.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
33
Preferably, the temperature of the plasticization step 100 is increased and/or
controlled by using hot water and/or water steam. Thus, the chemically
treated wood-based cellulosic material 10 is preferably treated with hot water
.. and/or water steam during the plasticization step 100. Thus, the
plasticization
step 100 can further comprise:
- feeding water steam and/or hot water to a continuous reactor 101
in
order to increase temperature of the continuous reactor 101.
Thanks to the water steam and/or the hot water, the viscosity controlled
cellulosic material 20 can be manufactured efficiently and environmentally
friendly. Furthermore, the hot water and/or water steam plasticization can be
economically viable. Most preferably, water steam is used to increase
temperature of the continuous reactor 101, because water steam can
efficiently spread into the chemically treated wood-based cellulosic material
10, and penetrate to fiber walls of the chemically treated wood-based
cellulosic material 10.
The duration of the plasticization step 100 is preferably less than 60
minutes,
for example 50 minutes at the most, more preferably less than 30 minutes,
for example 25 minutes at the most, and most preferably less than 20
minutes, for example 15 minutes at the most. Further, the duration of the
plasticization step 100 is preferably at least 4 minutes, more preferably at
least 5 minutes. Most advantageously, the duration of the plasticization step
is between 5 and 20 minutes. Thanks to the present invention having
continuous process, wherein the treated mixture is mixed during the
plasticization step, it is possible to obtain viscosity controlled cellulosic
material 20 having good properties by using a short treatment time while
avoiding steam explosion. Therefore, due to quite fast viscosity adjustment
and lower energy consumption during the plasticization step 100,
manufacturing costs can be remarkably decreased. Further, said shorter
reaction time increases the production capacity. Thus, viscosity controlled
cellulosic material can be manufactured with improved production efficiency.
Furthermore, properties of the viscosity controlled cellulosic material, such
as
a brightness and/or a polydispersity, can be improved.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
34
The plasticization step 100 can be carried out at a temperature of at least
130 C, more preferably at least 140 C and most preferably at least 150 C.
Further, temperature of the plasticization step 100 can be 200 C at the most,
more preferably 180 C at the most, and most preferably 170 C or 160 C at
.. the most. This quite low temperature, especially when used together with
quite low duration of the plasticization step 100, can cause remarkable
manufacturing cost savings due to lower energy consumption. Moreover, this
kind of temperature range, particularly if the temperature is 170 C at the
most, or 160 C at the most, can improve brightness of the obtained product.
The brightness value of the obtained product typically increases (i.e.,
improves) when the temperature of the process decreases.
A pressure during the plasticization step 100 can be at least 3 bar, more
preferably at least 4 bar, and most preferably at least 5 bar. Further,
pressure
of the steam treatment can be 15 bar at the most, more preferably 10 bar at
.. the most, and most preferably 8 bar at the most. This quite low pressure,
especially when used together with the above-mentioned duration of the
plasticization step 100, can cause remarkable manufacturing cost savings
together with improved properties for the manufactured viscosity controlled
cellulosic material. Moreover, this can improve the brightness of the obtained
product.
pH of the plasticization step 100 can be at least 1, more preferably at least
2,
and most preferably at least 3. In addition, pH of the plasticization step 100
can be 6 at the most, more preferably 5 at the most, and most preferably 4 at
the most, for example between 2 and 5. By using said pH ranges, it is
possible to obtain efficient manufacturing process for the viscosity
controlled
cellulosic material, said effect of pH improves when used together with the
above-mentioned pressure and duration of the plasticization step.
The cellulose-water mixture 15 can have a dry matter content (consistency)
between 3% and 20% during the plasticization step 100. The dry matter
content during the plasticization step 100 can be at least 5%, more preferably
at least 7%, and most preferably at least 10%. Further, the dry matter content
during the plasticization step 100 can be 18% at the most, more preferably
15% at the most, and most preferably 13% at the most. This consistency
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
range, particularly consistency between 5% and 15% or between 5% and
13%, can improve the properties of the manufactured viscosity controlled
cellulosic material.
5 During the plasticization step 100, a degree of polymerization can be
decreased at least 50%, more preferably at least 70%, and most preferably
at least 80%. This can improve an R18 solubility of the obtained product.
The depressurizing of the treated mixture 18 in the depressurizing step 105
10 after the plasticization step 100 can be done in a controlled manner to
avoid
steam explosion. Thus, the treated mixture 18 can be non-explosively
depressurized to the atmospheric pressure after the plasticization step 100.
Thus, the depressurizing step 105 is preferably substantially slow and
controlled i.e., implemented without a steam explosion. Therefore, the
15 depressurizing step 105 is not advantageously simply implemented, for
example, by opening a valve of the continuous reactor 101 and, hence,
blowing off the water steam from the continuous reactor 101. Thus, thanks to
the novel method, it is possible to maintain fiber integrity.
20 Suitable depressurization time depends, for example, on the pressure
under
which the plasticization step 100 is carried out.
The depressurizing step 105 may be implemented, for example, by adding
water to the treated mixture 18. The addition of water during the
25 depressurizing step can be implemented, for example, by using a chamber
method, wherein water is added into an intermediate chamber in order to
decrease a temperature and a pressure of the treated mixture 18. The
intermediate chamber can comprise at least one valve for letting the wood-
based cellulosic material into the chamber, and at least one another valve for
30 letting the wood-based cellulosic material out from the intermediate
chamber
after said depressurizing.
Further, the intermediate chamber can comprise at least one valve, for
example exactly one valve, for letting some water steam go out from the
35 chamber while adding the cold water.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
36
Alternatively, or in addition, the addition of the water can be implemented,
for
example, by using compartment valves.
Furthermore, the addition of the water can be implemented, for example, by
using a continuous screw reactor, wherein cold water is added into the
continuous screw reactor, such as to a last chamber of the screw reactor, in
order to decrease a temperature and a pressure of the treated mixture 18.
Therefore, the depressurizing step 105 can comprise the following step:
- cooling the treated mixture 18 by adding water.
The water used for the cooling has preferably a temperature less than 40 C,
for example between 5 C and 30 C. Temperature of the obtained viscosity
controlled cellulosic material after the depressurizing step is preferably
about
100 C, for example between 90 C and 110 C. Thus, effectiveness of the
possible following treatment(s) can be increased.
This kind of the gentle depressurizing step 105 can be used to maintain
integrity of the fibers.
Thus, the means for depressurizing the treated mixture 18 in the
depressurizing step can comprise means for adding water, preferably cold
water, to the treated mixture 18. Further, the means for depressurizing the
treated mixture 18 can comprise an openable valve. Further, the means for
depressurizing the mixture can comprise an intermediate chest. In this case,
the cold water is preferably added to the intermediate chest.
During the depressurizing step 105, the pressure can be decreased from the
pressure of the plasticization step to the standard atmosphere (i.e. standard
pressure, 1 atm), or to a pressure having below 1 bar difference to the
atmospheric pressure, preferably below 0.5 bar difference to the atmospheric
pressure. Thanks to the non-explosive depressurizing step 105, properties of
the manufactured viscosity controlled cellulosic material 20 may be
substantially improved. Especially, strength properties may be substantially
improved.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
37
After the depressurizing step 105, the obtained viscosity controlled
cellulosic
material 20 can be further treated, for example, as follows:
- washing the cellulosic material 20 in a washing step 110 and/or
- adjusting pH of the obtained viscosity controlled cellulosic material 20
in a pH adjusting step.
The washing step 110 can comprise the following step:
- washing the obtained viscosity controlled cellulosic material 20 with
water to remove excess acid.
Furthermore, the washing step 110 can comprise the following step:
- conveying at least part of the water used in the washing step to the
cellulose-water mixture 15.
Thus, in this embodiment, at least part of the water used for washing step
110 of the viscosity controlled cellulosic material 20 can be used for
diluting
the cellulose-water mixture 15 before the plasticization step. Thus, said
water
can increase a temperature of the cellulose-water mixture 15 before the
plasticization step. Furthermore, at least some of excess acid removed
during the washing step 110 can be circulated to the plasticization step and
reused therein.
Furthermore, the washing step 110 can comprise the following step:
- dewatering the washed viscosity controlled cellulosic material, for
example,
by pressing the viscosity controlled cellulosic material 20 to reach a dry
matter content between 10% and 50%, preferably at least 15%, more
preferably at least 20%, and preferably 45% at the most, more preferably
40% at the most.
The washing step 110 can be carried out, for example, by using a wash
press.
In an embodiment, pH of the viscosity controlled cellulosic material can be
adjusted, for example, by diluting the material with water, wherein the
viscosity controlled cellulosic material 20 is diluted to a predetermined pH.
Alternatively, or in addition, suitable chemical(s) known by a person skilled
in
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
38
the art, can be used for said pH adjustment. The predetermined pH can be,
for example, between 4 and 7, more preferably between 4 and 6.
Further, the method can comprise the following step, preferably following the
washing step 110 and/or the pH adjusting step:
- drying the obtained viscosity controlled cellulosic material 20 in
a
drying step 120 to reach a dry matter content of at least 50%.
Dry matter content of the viscosity controlled cellulosic material 20 after
the
drying step 120 can be between 50 and 100%, preferably between 80 and
90%.
The drying step 120 is typically needed, for example, for a transportation.
The drying step 120 may be implemented in a flash drying step using a flash
dryer. However, the flash dryer is not necessarily an economical device.
Thus, more advantageously, the drying step is implemented, for example, by
using a drying machine of a pulp mill. Therefore, the drying step 120 may be
implemented without a large investment.
If the manufacturing process is an integrated process, for example, in a pulp
mill, there may not be any need for the drying step 120 of the obtained
viscosity controlled cellulosic material before, for example, a regenerated
cellulose material is formed from the viscosity controlled cellulosic material
20.
Thanks to the novel method, the obtained viscosity controlled cellulosic
material 20 can have a viscosity value in a range between 150 ml/g and 500
ml/g. Preferably, the viscosity value of the viscosity controlled cellulosic
material is at least 160 ml/g, more preferably at least 170 ml/g, and most
preferably at least 180 ml/g. Further, preferably the viscosity value of the
viscosity controlled cellulosic material is 350 ml/g at the most, more
preferably 300 ml/g at the most, and most preferably 250 ml/g at the most.
The viscosity controlled cellulosic material 20 can have a special
hemicellulose content due to the novel method. Hemicellulose content of the
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
39
obtained viscosity controlled cellulosic material 20 can be between 0.5 wt.-
%and 30 wt.-%. Hemicellulose content of the viscosity controlled cellulosic
material 20 is preferably at least 1 wt.-%, more preferably at least 3 wt.-%,
and most preferably at least 5 wt.-%. Further, the hemicellulose content of
the viscosity controlled cellulosic material 20 is preferably 30 wt.-% at the
most, more preferably 25 wt.-% at the most. The technical effect of said
hemicellulose content includes an improved yield and a material efficiency,
an improved environmental impact as well as an improved reactivity.
The viscosity controlled cellulosic material 20 can have a special glucose
content due to the novel method. Said glucose content the obtained viscosity
controlled cellulosic material 20 can be between 76 wt.-% and 99.6 wt.-%
calculated from the total sugar content of the viscosity controlled cellulosic
material. Said glucose content of the viscosity controlled cellulosic material
20 is preferably at least 80 wt.-%, more preferably at least 85 wt.-%, and
most preferably at least 90 wt.-% calculated from the total sugar content of
the viscosity controlled cellulosic material. In addition, said glucose
content of
the viscosity controlled cellulosic material 20 is preferably 99 wt.-% at the
most, and more preferably 95 wt.-% at the most, calculated from the total
sugar content of the viscosity controlled cellulosic material. The technical
effect of said glucose content includes an improved material efficiency.
An alpha cellulose content of the viscosity controlled cellulosic material is
preferably at least 67%, more preferably at least 69%. Further, the alpha
cellulose content of the viscosity controlled cellulosic material is
preferably
less than 99.5%, more preferably less than 95%, and most preferably 90% at
the most. The technical effect is an improved yield, an improved reactivity
and a material efficiency, as well as better environmental impact.
The obtained viscosity controlled cellulosic material 20 can have a degree of
polymerization between 200 and 700. The degree of polymerization is
preferably at least 220, more preferably at least 250, and most preferably at
least 300. Further, the degree of polymerization is preferably 650 at the
most,
more preferably 620 at the most, and most preferably 600 at the most.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
The viscosity controlled cellulosic material 20 can have a special fiber
length
due to the novel method. Advantageously, a content of fibers having length
below 0.6 mm, measured from the viscosity controlled cellulosic material, is
between 10% and 30%. The technical effect is that this kind of viscosity
5 controlled material can be very easy to handle and wash and, further,
yield
loss can be decreased.
Moreover, thanks to the novel method, the length weighted fiber length Lc(I)
of the viscosity controlled cellulosic material measured according to ISO
10 16065-N can be more than 0.5 mm, for example at least 0.7 mm, more
preferably at least 0.9 mm or at least 1.0 mm, and most preferably at least
1.2 mm. Further, the average fiber length of the viscosity controlled
cellulosic
material 20 can be 3.0 mm at the most. The fiber length of the viscosity
controlled cellulosic material depends on the fiber length of the raw
material,
15 which is affected, for example, by the amount of softwood and/or
hardwood
raw materials. Said length weighted fiber length of the viscosity controlled
cellulosic material can improve strength properties of the product. Especially
bursting strength of an end product can be improved.
20 Good optical properties may be important for the viscosity controlled
cellulosic material 20. With the novel method, ISO Brightness of the viscosity
controlled cellulosic material can be at least 70%, for example between 75%
and 90%. Thus, a quality of the end-product can be increased.
25 A curliness of the viscosity controlled cellulosic material can be
between
20% and 90%, more preferably between 25% and 85%, and most preferably
between 30% and 65%.This may improve strength properties of the end-
product. Further, said curliness can improve water removing properties of the
product.
Further, a WRV of the viscosity controlled cellulosic material 20 is
preferably
between 1 g/g and 2 g/g. The technical effect is an improved chemical
access together with an improved reaction efficiency, i.e. decreased reaction
time.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
41
To achieve good properties for the viscosity controlled cellulosic material,
the
lignin content of the viscosity controlled cellulosic material can be less
than
1.5%, more preferably less than 1%, and most preferably less than 0.5%.
Further, an extractive content of the viscosity controlled cellulosic material
is
preferably less than 0.2%, more preferably less than 0.1%. Decreased lignin
and extractive contents of the product improves a brightness and a quality of
the product.
The viscosity controlled cellulosic material 20 can have a special
crystallinity
index Crl due to the novel method. The obtained viscosity controlled
cellulosic material 20 can have a crystallinity index of at least 74%, more
preferably at least 75%, and most preferably at least 76%. In addition,
crystallinity index of the obtained viscosity controlled cellulosic material
can
be less than 85%, for example 80% at the most. Thanks to the novel method,
it is possible to obtain said improved crystallinity index which can improve
properties, such as strength properties, of the product.
A sodium (Na) content of the viscosity controlled cellulosic material can be
at
least 200 mg/kg, preferably 200¨ 1500 mg/kg based on the dry weight of the
chemically treated wood-based cellulosic material fibers. Sodium content has
an effect on a viscosity value of the obtained product. Too high sodium
content of the viscosity controlled cellulosic material may cause too high
viscosity value for the product.
Thanks to the novel method, the novel viscosity controlled cellulosic material
can have a special R18 solubility of the viscosity controlled cellulosic
material
20. R18 solubility of the viscosity controlled cellulosic material can be at
least
60%, more preferably at least 65% and most preferably at least 70%. In
addition, R18 solubility of the viscosity controlled cellulosic material is
preferably 87% at the most, most preferably 84% at the most. Thanks to this
novel R18 solubility of the viscosity controlled cellulosic material, an
environmentally friendly product can be obtained. Moreover, a yield as well
as a production efficiency can be improved.
The viscosity controlled cellulosic material 20 can be dissolvable in an
aqueous solution of alkali metal hydroxide at a temperature between -5 C
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
42
and 0 C, typically at a temperature between -10 C and 5 C in order to form
homogenous cellulose solution. Most preferably, the viscosity controlled
cellulosic material 20 is dissolvable at least to a cold NaOH having a
temperature within the above-mentioned temperature range. NaOH can help
to obtain relatively inexpensive and environmentally friendly aqueous alkali-
based solution.
The viscosity controlled cellulosic material 20 can be dissolved in aqueous
alkaline solutions to form a dissolved viscosity controlled cellulosic
material
30. Further, a regenerated cellulose material 40 can be obtained from the
dissolved viscosity controlled cellulosic material 30. Thanks to an activation
of fibres in the plasticization step 100, reactiveness of the fibres can be
increased and, hence, the viscosity controlled cellulosic material can be
easily modified into the regenerated cellulose material 40. Furthermore, the
water steam, if used during the plasticization step, can decrease
crystallinity
of the viscosity controlled cellulosic material.
The dissolved viscosity controlled cellulosic material 30, which can also be
called as "a dope", may be raw material for other products, such as fibers.
The dissolved viscosity controlled cellulosic material 30 i.e., the dope, can
be
used, for example, for filaments, staple fibers, cellulose beads, and/or
films.
A method for processing the obtained viscosity controlled cellulosic material
20 to form the regenerated cellulose material 40 can comprise the following
steps:
- dissolving the viscosity controlled cellulosic material 20 in a
dissolving step 130 by using an aqueous alkaline, thereby forming a
dissolved viscosity controlled cellulosic material 30, and
- forming the regenerated cellulose material 40 from the dissolved
viscosity controlled cellulosic material 30.
The concentration of the viscosity controlled cellulosic material in a
dissolving
step 130 is preferably between Sand 10%.
The aqueous alkaline can comprise
- NaOH,
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
43
- Li0H, and/or
- KOH,
and/or a mixture of any of the above mentioned with zinc compounds
Advantageous, at least NaOH is used for the dissolving step 130, because
NaOH is substantially cost-effective chemical which may be easy to use in
the process.
The addition of the zinc compounds to the alkali hydroxide solution can, for
example, increase the stability of the solution. A stability time of the
dissolved
viscosity controlled cellulosic material 30 can be, for example, 30 d at a
room
temperature, 180 days in fridge.
Optionally, additives such as colorants, surface active agents, ultra-violet
degradation inhibitors, anti-fungicidal components, anti-microbial
components, inorganic fillers or other components may be blended into the
dissolved viscosity controlled cellulosic material 30.
The novel process can be technologically simple and ecologically safe
process without a need of toxic substances. Further, the novel process can
be inexpensive due to small chemical consumption and substantially simple
technology.
Experimental tests, Example 1
Three similar samples were treated by using different kind of manufacturing
methods. The results can be seen in Figures 4a - 4c. The treatments were as
follows:
- Sample 1A: viscosity controlled cellulosic material manufactured with
a steam explosion by using a batch process (Fig. 4a),
- Sample 2A: viscosity controlled cellulosic material manufactured
without a steam explosion by using a batch process (Fig. 4b), and
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
44
- Sample 3A: viscosity controlled cellulosic material manufactured
without a steam explosion by using a continuous process (Fig. 4c).
As can be seen from the photos, the sample 3, which was manufactured
without the steam explosion by using the continuous process, has improved
optical properties, such as an improved brightness value comparing to the
sample 1. Further, fibers of the sample 1 were much more damaged than
fibers of the sample 3.
Example 2
Three different samples were analyzed under a light microscope. The results
can be seen in Figures 5a - Sc. Said samples were stained with Graff-C.
Sample 1B (Figure 5a) was a kraft pulp, which was used as a raw material,
Sample 2B (Figure 5b) was a viscosity controlled cellulosic material, and
Sample 3B (Figure Sc) was a steam exploded cellulosic material.
Fibers of the sample 1 were straight and intact with clearly visible typical
pores. Some of the Kraft fibers had loose outer fibril layer and kinks typical
for kraft fibers.
Fibers of the sample 2 were clearly more fibrillated on the surface and they
had gained a loose structure. The fibers were quite curly. The fiber structure
is probably absorbing and easy to disintegrate.
The sample 3 consists of crystalline material and some slender fibers.
As can be seen from the Figures 5b and Sc, the continuous process without
the steam explosion has maintained the fiber integrity, but the steam
explosion process has almost destroyed the fibers.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
Example 3
During the experimental tests, several pulp samples were treated in a
plasticization step and properties of the treated pulps were measured. These
5 results are shown in Figures 6-11.
Sample A was a never dried conifer pulp which was treated without a steam
explosion by using a batch type of reactor having the following parameters:
Temperature: 170 C,
10 Pressure: 7 bar,
Time: 120 min, and
pH: 3.3.
Sample B was a never dried conifer pulp which was treated without a steam
15 .. explosion by using a continuous reactor having the following parameters:
Temperature: 170 C,
Pressure: 7 bar,
Time: 20 min, and
pH: 3.3.
Sample C was a never dried conifer pulp which was treated without a steam
explosion by using a continuous reactor having the following parameters:
Temperature: 170 C,
Pressure: 7 bar,
Time: 50 min, and
pH: 3.3.
Sample D was a never dried conifer pulp which was treated without a steam
explosion by using a semi-continuous reactor having the following
parameters:
Temperature: 160 C,
Pressure: 6 bar,
Time: 25 min, and
pH: 3.3.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
46
Sample E was a never dried conifer pulp which was treated without a steam
explosion by using a semi-continuous reactor having the following
parameters:
Temperature: 160 C,
Pressure: 6 bar,
Time: 10 min, and
pH: 3.3.
Sample F was a dried conifer pulp which was treated without a steam
explosion by using a semi-continuous reactor having the following
parameters:
Temperature: 160 C,
Pressure: 6 bar, and
Time: 25 min.
Sample G was a dried conifer pulp which was treated without a steam
explosion by using a batch type of reactor having the following parameters:
Temperature: 170 C,
Pressure: 7 bar,
Time: 120 min, and
pH: 4Ø
Sample H was a dried conifer pulp which was treated with a steam explosion
method by using a continuous reactor having the following parameters:
Temperature: 190 C,
Pressure: 10 bar,
Time: 5 min, and
pH: 4Ø
Samples I and J were never dried birch pulps which were treated by using a
continuous reactor having the following parameters:
Temperature: 170 C,
Pressure: 7 bar,
Time: 50 min, and
pH: 3.3.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
47
Samples K and L were never dried conifer pulps which were treated by using
a continuous reactor having the following parameters:
Temperature: 170 C,
Pressure: 7 bar,
Time: 50 min, and
pH: 10.3.
Reference samples Ref1 and Ref2 were (untreated) never dried conifer
pulps.
Molar mass distribution by tricabanilate (RI detection), Mw [g/mol], of all
samples is illustrated in Figures 6a and 6b. As can be seen, the samples
obtained by using continuous and semi-continuous processes (Samples B,
C, D, E, F) had improved properties comparing to the samples obtained by
using a batch process (Sample A and G).
Viscosity values of the samples are illustrated in Figure 7. As can be seen,
pH had an effect on the viscosity values of the manufacture product. High pH
(Samples K and L) increased the viscosity value of the manufactured
product. Further, surprisingly, a batch process (Samples A and G) was very
ineffective way to manufacture the viscosity controlled cellulosic material.
The samples A and G obtained from the batch processes had higher
viscosity values than the samples obtained from the continuous processes.
On the contrary, the continuous process seemed to be very efficient. The
viscosity values were lower in the samples B-F and H obtained from the
continuous process (having a reaction time between 10 and 50 min) than in
the samples A and G obtained from the batch process (having a reaction
time around 120 min).
The viscosity values of the samples decreased along with the increased
reaction temperature and/or reaction time. As can be seen, it is possible to
obtain the viscosity controlled cellulosic material in an effective way by
using
the claimed method. Hence, thanks to the novel method, the production
efficiency can be increased significantly. Further, due to the decreased
reaction time and/or the decreased reaction temperature, the properties of
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
48
the obtained viscosity controlled cellulosic material, such as a brightness
value of the obtained product, can be significantly increased.
Length weighted fiber lengths of the samples are shown in Figure 8a. As can
be seen, the sample H, manufactured by using a steam explosion process,
had the shorter fibers. Fibers of said sample H (manufactured by using the
steam explosion method) seemed to be so broken that a length weighted
fiber length of the sample H had been reduced to the same level with the
samples I and J having a birch pulp as a raw material. The length weighted
fiber lengths of the samples A-G and K-L, manufactured without the steam
explosion, were at a very good level.
Further, the continuous process seemed to be very efficient. Fiber lengths of
those samples, which were manufactured by using a continuous process,
had already decreased when the treatment time was 50 minutes. Thus, with
the continuous process also a very short time, such as around 10 minutes,
can be sufficient for the process. A longer treatment time was needed for the
batch processes than for the continuous processes. Therefore, with the
continuous process, the production efficiency can be improved, and a quality
of the product can be better than a quality of the product manufactured by
using the steam explosion method.
A fiber curl [%] is illustrated in Figure 8b. As can be seen, the fiber
curliness
was very small in Sample H due to the steam explosion process. Further, the
samples A and G, which were obtained from the batch processes, as well as
the sample C, which was obtained from the continuous process having a
quite long treatment time together with a quite high temperature, had
decreased curliness values. Furthermore, high pH (Samples K and L) and a
birch pulp as a raw material (Samples I and J) seemed to decrease the
curliness of fiber. The samples B, D, E and F, which were obtained from the
continuous processes having a treatment time between 10 and 25 min, had
the most promising results.
A Kink value [1/m] is illustrated in Figure 9a. As can be seen, the kink value
was the smallest in the samples A and G (batch processes). In addition, the
kink value was a little bit low in the sample H (steam explosion process). The
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
49
kink value was the highest with the samples which were manufactured
without a steam explosion by using a continuous process.
Fibrillation is illustrated in Figure 9b. As can be seen, the samples
manufactured without a steam explosion by using the continuous processes
had slightly higher fibrillation level than the samples manufactured by using
the batch processes. The steam explosion process (sample H) can destroy a
structure of fibres, thereby causing a very high fibrillation level.
A polydispersity is illustrated in Figure 10. The polydispersity value of the
samples manufactured by using the continuous process was improved. The
continuous processes seemed to be very efficient. The sample E obtained
from the continuous process having a very short treatment time (10 min) had
the same polydispersity level as the samples A and G obtained from batch
processes having a long treatment time (120 min). Therefore, by using the
continuous process, it is possible to improve the production efficiency.
Crystallinity index by XRD [%] is illustrated in Fig. 11. Crystallinity index
typically increases due to the plasticization process.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
The following numbered examples disclose some examples of preferred
embodiments of the invention.
Numbered examples
5
1. A method for producing viscosity controlled cellulosic material having a
viscosity value in a range between 150 ml/g and 500 ml/g in a continuous
process, the method comprising the following steps:
i) forming a cellulose-water mixture 15 comprising
10 - water and
- chemically treated wood-based cellulosic material comprising
bleached kraft pulp, and/or bleached sulfite pulp and/or
bleached soda pulp,
the cellulose-water mixture having a dry matter content between 3 and 20%,
15 ii) treating the formed cellulose-water mixture 15 in a
plasticization step
(100) at a temperature between 130 C and 200 C and a pressure
between 3 bar and 15 bar, preferably between 5 bar and 10 bar at
least 5 minutes and 120 minutes at the most, while
- mixing the cellulose-water mixture 15, and
20 - feeding hot water and/or water steam to the cellulose-water
mixture,
thereby obtaining a treated mixture 18,
and
iii) depressurizing the treated mixture 18 after the plasticization
step 100
25 in a depressurizing step 105 in a controlled manner without a
steam
explosion to maintain fiber integrity, thereby obtaining the viscosity
controlled cellulosic material 20.
2. The method according to example 1, wherein the plasticization step 100 is
30 implemented by treating the formed cellulose-water mixture 15 in a
continuous kneader reactor.
3. The method according to any of the preceding examples, wherein the
plasticization step 100 is implemented by treating the formed cellulose-water
35 mixture 15 in a continuous screw reactor.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
51
4. The method according to example 3, wherein the continuous screw reactor
is a horizontal screw reactor.
5. The method according to any of the preceding examples, wherein the
depressurizing step comprises the following step:
- cooling the treated mixture 18 by adding water.
6. The method according to any of the preceding examples, wherein the
depressurizing step 105 comprises:
- reducing water vapor mechanically, for example by using a screw or
a chamber method.
7. The method according to any of the preceding examples, wherein the
depressurizing step 105 takes 30 minutes at the most, preferably 20 minutes
at the most.
8. The method according to any of the preceding examples, wherein the
depressurizing step 105 takes at least 1 second, preferably at least 3
seconds.
9. The method according to any of the preceding examples, wherein the
method further comprises
- dosing an activator into the cellulose-water mixture 15 in order
to
plasticize the wood-based cellulosic material in the presence of the
activator during said plasticization step 100.
10. The method according to example 9, wherein the activator comprises a
filtrate obtained from the plasticization step, wherein the filtrate
preferably
comprises hydrolysate products from the plasticization step.
11. The method according to example 10, wherein the amount of the filtrate
obtained from the plasticization step is at least 90%, more preferably at
least
95%, and most preferably at least 99% or exactly 100% calculated from the
total amount of the activator.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
52
12. The method according to example 9, 10 or 11, wherein the activator
comprises sulfuric acid or acetic acid, the total amount of the sulfuric acid
and the acetic acid being less than 5%, more preferably less than 3%, and
most preferably less than 2% calculated from the dry weight of the chemically
treated wood-based cellulosic material 10.
13. The method according to any of the preceding examples 9 to 12, wherein
the activator comprises acid solutions, preferably acid filtrates from a
chemical pulp mill.
14. The method according to any of the preceding examples, wherein the
total usage of chemicals, excluding the filtrate obtained from the
plasticization
step, is less than 5%, for example less than 2 %, calculated from the dry
weight of the chemically treated wood-based cellulosic material 10.
15. The method according to any of the preceding examples, wherein the
treated mixture 18 is depressurized to a pressure having below 1 bar
difference to the atmospheric pressure in the depressurizing step 105,
preferably below 0.5 bar difference to the atmospheric pressure.
16. The method according to any of the preceding examples, wherein the
duration of the plasticization step 100 is 50 minutes at the most, preferably
20 minutes at the most, and most preferably 15 minutes at the most.
17. The method according to any of the preceding examples, wherein the
duration of the plasticization step 100 is at least 6 minutes.
18. The method according to any of the preceding examples, wherein the
temperature of the plasticization step 100 is at least 140 C, preferably at
least 150 C.
19. The method according to any of the preceding examples, wherein the
pressure of the plasticization step 100 is at least 5 bars, preferably at
least 6
bars.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
53
20. The method according to any of the preceding examples, wherein the
pressure of the plasticization step 100 is less than 10 bar, preferably 8 bar
at
the most.
21. The method according to any of the preceding examples, wherein the
temperature of the plasticization step 100 is 180 C at the most, preferably
170 C at the most.
22. The method according to any of the preceding examples, wherein pH of
the cellulose-water mixture is 6 at the most, preferably 5 at the most.
23. The method according to any of the preceding examples, wherein pH of
the cellulose-water mixture is at least 1, preferably at least 2.
24. The method according to any of the preceding examples, wherein the
viscosity of the wood-based cellulosic material determined from the cellulose-
water mixture before the plasticization step is at least 400 ml/g, preferably
at
least 450 ml/g .
25. The method according to any of the preceding examples, wherein the
viscosity of the wood-based cellulosic material determined from the cellulose-
water mixture before the plasticization step is 1200 ml/g at the most,
preferably 900 ml/g at the most.
26. The method according to any of the preceding examples, wherein said
dry matter content of the cellulose-water mixture 15 is at least 5%, more
preferably at least 10%.
27. The method according to any of the preceding examples, wherein said
dry matter content of the cellulose-water mixture 15 is less than 17% more
preferably less than 14%.
28. The method according to any of the preceding examples, characterized in
a mixing efficiency during the plasticization step is between 15 and 80
kWh/ADt.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
54
29. The method according to any of the preceding examples, wherein the
viscosity value of the viscosity controlled cellulosic material 20 is at least
170
ml/g, preferably at least 180 ml/g.
30. The method according to any of the preceding examples, wherein the
viscosity value of the viscosity controlled cellulosic material 20 is 350 ml/g
at
the most, preferably 300 ml/g at the most and most preferably 250 ml/g at the
most.
31. The method according to any of the preceding examples, wherein the
method further comprises
- washing the obtained viscosity controlled cellulosic material 20 in a
washing step, preferably by using water, and/or
- adjusting pH of the obtained viscosity controlled cellulosic material in
a pH adjusting step.
32. The method according to any of the preceding examples, wherein the
method further comprises
- drying the obtained viscosity controlled cellulosic 20 material to
obtain a dry matter content of at least 60%.
33. The method according to any of the preceding examples, wherein ISO
Brightness of the chemically treated wood-based cellulosic material
determined before the plasticization step is at least 70%, preferably at least
86%.
34. The method according to any of the preceding examples, wherein a
hemicellulose content of the of the cellulose-water mixture is at least 0.5%,
preferably between 10% and 33%, based on a dry weight of the chemically
treated wood-based cellulosic material.
35. The method according to any of the preceding examples, wherein a
crystallinity index of the viscosity controlled cellulosic material is at
least 74%,
preferably at least 76%.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
36. The method according to any of the preceding examples, wherein an
extractive content of the chemically treated wood-based cellulosic material
measured from the cellulose-water mixture before the plasticization step 100
is less than 0.4%, preferably less than 0.2% based on a dry weight of the
5 chemically treated wood-based cellulosic material in the mixture.
37. The method according to any of the preceding examples, wherein an ash
content of the chemically treated wood-based cellulosic material measured
from the cellulose-water mixture is less than 0.7%, more preferably less than
10 0.5% based on a dry weight of the chemically treated wood-based
cellulosic
material in the mixture.
38. The method according to any of the preceding examples, wherein a
content of fibers having length below 0.6 mm, determined before the
15 plasticization step 100 from the cellulose-water mixture, is between 10
and
30%, based on the total content of the chemically treated wood-based
cellulosic material fibers.
39. The method according to any of the preceding examples, wherein a
20 curliness of the wood-based cellulosic material measured before the
plasticization step 100 is between 7% and 40%.
40. The method according to any of the preceding examples, wherein sodium
(Na) content of the cellulose-water mixture 15 is at least 200 mg/kg,
25 preferably between 200 mg/kg and 1500 mg/kg based on the dry weight of
the chemically treated wood-based cellulosic material fibers.
41. The method according to any of the preceding examples, wherein a WRV
value of the cellulose-water mixture is between 1-2 g/g.
42. The method according to any of the preceding examples, wherein a
softwood content of the chemically treated wood-based material is at least
70%, more preferably at least 85% based on a dry weight of the chemically
treated wood-based cellulosic material.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
56
43. The method according to any of the preceding examples, wherein an
alpha cellulose content of the chemically treated wood-based cellulosic
material 10 measured before the plasticization step 100 is at least 65%,
preferably at least 67%.
44. The method according to any of the preceding examples, wherein alpha
cellulose content of the chemically treated wood-based cellulosic material 10
measure before the plasticization step 100 is less than 99.5%, more
preferably 90% at the most.
45. The method according to any of the preceding examples, wherein a lignin
content of the chemically treated wood-based cellulosic material 10
measured before the plasticization step 100 is less than 3%, more preferably
less than 1.0%, most preferably less than 0.5%.
46. The method according to any of the preceding examples, wherein a
length weighted fiber length Lc(I) of the viscosity controlled cellulosic
material
measured according to ISO 16065-N is at least 0.9 mm, more preferably
at least 1.0 mm, and most preferably at least 1.2 mm.
47. The method according to any of the preceding examples, wherein an
alpha cellulose content of the viscosity controlled cellulosic material 20 is
at
least 67%, preferably at least 69%.
48. The method according to any of the preceding examples, wherein alpha
cellulose content of the viscosity controlled cellulosic material 20 is less
than
99.5%, preferably 90% at the most.
49. The method according to any of the preceding examples, wherein a
hemicellulose content of the viscosity controlled cellulosic material 20 is at
least 0.5% dry wt.%, more preferably at least 5 dry wt.%.
50. The method according to any of the preceding examples, wherein
hemicellulose content of the viscosity controlled cellulosic material 20 is
between 10% and 30 dry wt.%.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
57
51. The method according to any of the preceding examples, wherein an R18
solubility of the viscosity controlled cellulosic material 20 is at least 60%,
preferably at least 70%.
52. The method according to any of the preceding examples, wherein R18
solubility of the viscosity controlled cellulosic material 20 is 87% at the
most,
preferably 84% at the most.
53. The method according to any of the preceding examples, wherein a
sodium (Na) content of the viscosity controlled cellulosic material 20 is at
least 200 mg/kg, preferably in a range of 200 - 1500 mg/kg based on the dry
weight of the chemically treated wood-based cellulosic material fibers.
54. The method according to any of the preceding examples, wherein a
content of fibers having length below 0.6 mm, measured from the viscosity
controlled cellulosic material 20, is between 10% and 30%.
55. The method according to any of the preceding examples, wherein ISO
Brightness of the viscosity controlled cellulosic material 20 is at least 70%,
preferably between 75% and 90%.
56. The method according to any of the preceding examples, wherein a
curliness of the viscosity controlled cellulosic material 20 is between 25%
and
90%, preferably between 35% and 80%.
57. The method according to any of the preceding examples, wherein a WRV
of the viscosity controlled cellulosic material 20 is between 1 g/g and 2 g/g.
58. The method according to any of the preceding examples, wherein a lignin
content of the viscosity controlled cellulosic material 20 is less than 1.5%,
more preferably less than 1%, and most preferably less than 0.5%.
59. The method according to any of the preceding examples, wherein an
extractive content of the viscosity controlled cellulosic material 20 is less
than
0.2%, more preferably less than 0.1%.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
58
60. A viscosity controlled cellulosic material obtainable by using any of the
preceding examples 1 to 59.
61. A system for producing viscosity controlled cellulosic material 20 having
a
viscosity value in a range between 150 ml/g and 500 ml/g in a continuous
process, the system comprising:
- means for forming a cellulose-water mixture,
- a continuous reactor 101, such as a continuous kneader, for treating
the cellulose-water mixture in a plasticization step 100 at a
temperature between 130 C and 200 C,
- mixing means for mixing the cellulose-water mixture during the
plasticization step,
- heating means for increasing temperature of the cellulose-water
mixture in the continuous reactor, such as a feeder to feed water
steam to the continuous reactor, and
- means for depressurizing the treated mixture 18 in a controlled
manner without a steam explosion after the plasticization step 100.
62. The system according to example 61, wherein the continuous reactor 101
is a horizontal screw reactor.
63. The system according to example 61 or 62, wherein the system further
comprises
- means for dosing an activator to the cellulose-water mixture in order
to treat the cellulose-water mixture in the presence of the activator in
the plasticization step 100, such as means for conveying at least part
of a filtrate 102 obtained from the plasticization step to the
continuous reactor.
64. A viscosity controlled cellulosic material having a viscosity value in a
range between 150 ml/g and 500 ml/g, wherein the viscosity controlled
cellulosic material 20 has an R18 solubility between 60% and 87%.
65. The viscosity controlled cellulosic material according to example 64,
wherein the viscosity controlled cellulosic material 20 is manufactured from
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
59
chemically treated wood-based cellulosic material 10 comprising bleached
Kraft pulp, bleached sulfite pulp and/or bleached soda pulp.
66. The viscosity controlled cellulosic material according to example 64 or
65,
.. wherein a length weighted fiber length Lc(I) of the viscosity controlled
cellulosic material 20 measured according to ISO 16065-N is at least 0.9 mm,
more preferably at least 1.0 mm, and most preferably at least 1.2 mm.
67. The viscosity controlled cellulosic material according to any of the
preceding examples 64 to 66, wherein an alpha cellulose content of the
viscosity controlled cellulosic material is at least 67%, preferably at least
69%.
68. The viscosity controlled cellulosic material according to any of the
preceding examples 64 to 67, wherein an alpha cellulose content of the
viscosity controlled cellulosic material is less than 99.5%, preferably 90% at
the most.
69. The viscosity controlled cellulosic material according to any of the
preceding examples 64 to 68, wherein a hemicellulose content of the
viscosity controlled cellulosic material is at least 0.5% dry wt.%, more
preferably at least 5 dry wt.%.
70. The viscosity controlled cellulosic material according to any of the
preceding examples 64 to 69, wherein a hemicellulose content of the
viscosity controlled cellulosic material is between 10 dry wt.% and 30 dry
wt.%.
71. The viscosity controlled cellulosic material according to any of the
preceding examples 64 to 70, wherein the R18 solubility is at least 70%.
72. The viscosity controlled cellulosic material according to any of the
preceding examples 64 to 71, wherein the R18 solubility is 84% at the most.
73. The viscosity controlled cellulosic material according to any of the
preceding examples 64 to 72, wherein a sodium (Na) content of the viscosity
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
controlled cellulosic material 20 is at least 200 mg/kg, preferably in a range
of
200 ¨ 1500 mg/kg based on the dry weight of the chemically treated wood-
based cellulosic material fibers.
5 74. The viscosity controlled cellulosic material according to any of the
preceding examples 64 to 73, wherein a content of fibers having length below
0.6 mm in the viscosity controlled cellulosic material 20 is between 10% and
30%.
10 .. 75. The viscosity controlled cellulosic material according to any of the
preceding examples 64 to 74, wherein ISO Brightness of the viscosity
controlled cellulosic material is at least 70%, preferably between 75% and
90%.
15 76. The viscosity controlled cellulosic material according to any of the
preceding examples 64 to 75, wherein a curliness of the viscosity controlled
cellulosic material 20 is between 25% and 90%, preferably between 30% and
85%.
20 77. The viscosity controlled cellulosic material according to any of the
preceding examples 64 to 76, wherein a WRV of the viscosity controlled
cellulosic material 20 is between 1 g/g and 2 g/g.
78. The viscosity controlled cellulosic material according to any of the
25 preceding examples 64 to 77, wherein a lignin content of the viscosity
controlled cellulosic material 20 is less than 1.5%, more preferably less than
1`)/0, and most preferably less than 0.5%.
79. The viscosity controlled cellulosic material according to any of the
30 preceding examples 64 to 78, wherein an extractive content of the
viscosity
controlled cellulosic material 20 is less than 0.2%, more preferably less than
0.1%.
80. The viscosity controlled cellulosic material according to any of the
35 preceding examples 64 to 79, wherein the viscosity value of the
viscosity
controlled cellulosic material is at least 170 ml/g, preferably at least 180
ml/g.
CA 03139848 2021-11-09
WO 2020/229722 PCT/F12019/050371
61
81. The viscosity controlled cellulosic material according to any of the
preceding examples 64 to 80, wherein the viscosity value of the viscosity
controlled cellulosic material 20 is 350 ml/g at the most, preferably 320 ml/g
at the most.
82. A regenerated cellulosic material comprising the viscosity controlled
cellulosic material 20 according to any of the preceding examples 60 or 64 to
81.
