WO2025071399A1

WO2025071399A1 - Method for preparing a cellulose-containing pulp from a gramineous material

Info

Publication number: WO2025071399A1
Application number: PCT/NL2024/050518
Authority: WO
Inventors: Romkje Ytje MARKESTEIJN VAN DER WEIDE; Kimberly WEVERS; Stefan Johannes Everardus HOL; Jacobus Petrus VAN BRUGGE; Edwin Richard Peter Keijsers; Durk Lieuwe DURKSZ; Gosse HIEMSTRA
Original assignee: Hiemstra Bruin BV; Wageningen Universiteit
Current assignee: Hiemstra Bruin BV; Wageningen Universiteit
Priority date: 2023-09-25
Filing date: 2024-09-25
Publication date: 2025-04-03
Anticipated expiration: 2026-03-25

Abstract

The invention is in the field of cellulose-containing pulp for paper production. In particular, the invention is directed to a method for preparing cellulose-containing pulp that is suitable for paper production from gramineous material. The invention is further directed to cellulose-containing pulp obtainable from a gramineous material and a paper-based product comprising the cellulose-containing pulp obtainable from a gramineous material.

Description

Title: Method for preparing a cellulose-containing pulp from a gramineous material

Currently, wood is typically used as raw material for paper production. Wood is suitable as raw material, as it comprises cellulose and lignin. Cellulose is needed as the starting material for paper production. It is known that paper strength depends on lignin and cellulose contents of the raw plant materials. The presence of lignin increases the pH of the paper, which results in a more yellowish color. This is typically considered undesirable for high-quality paper. Therefore, lignin content is often reduced. This generally requires chemical and energy input during the pulping process. However, this poses a challenge as the polysaccharide components are preferably not disrupted by this chemical and energy input.

There are two main methods to reduce the lignin content and to produce a pulp.

The first type is the Kraft process. The process starts by removing the bark of the wood by a debarking drum to form the chips. The wood chips are cooked in an alkaline sulfate at temperatures between 150 °C and 170 °C. The removed bark is used as energy input for an auxiliary boiler. A mixture of hydroxyl (OH-) and hydrosulfide (HS-), generally known as white liquor, is used to cook the wood chips into a wood pulp. The pulp typically contains a high content of dissolved organic and soluble inorganic materials that need to be washed out. The washed pulp is screened, bleached and dried until it can be processed into paper. There are typically leftovers from this process, called black liquor. In general, this black liquor mainly comprises hemicellulose and lignin. The black liquor is evaporated to concentrate the stream, and fed to a recovery boiler. Fractions that are not combusted form a hot molten inorganic flow, mainly comprising sodium carbonate and sodium sulfide. The molten flow may be reused.

The second type is mechanical pulping. Generally, mechanical pulping allows for higher yields, but the paper strength is generally lower than that of paper formed from pulp originating from e.g. the Kraft process. The brightness of the paper may be lower than that of paper formed from pulp originating from e.g. the Kraft process, making it more suitable for i.a. newspapers and books.

Mechanical pulping may be separated into four categories, being, groundwood pulping, refiner mechanical pulping (RMP), thermomechanical pulping (TMP) and chemithermo-mechanical pulping (CTMP).

Groundwood pulping is based on the principle that the raw material is driven into a fast-revolving grindstone. Paper produced from this method is high in bulk (cm³/g) but has a low strength.

RMP is developed to overcome this issue and to make stronger paper. However, this process is energy intensive and costly.

For TMP, wood is chipped before the stream is fed into a steam heated refiner. The chips are refined between two steel disks into fibers.

CTMP uses a mild alkali pre-treatment of the fibers before refinement (which is similar to TMP), resulting in pulps with a longer fiber fraction and a lower fines fraction.

Furthermore, chemical and mechanical pulping may be combined into a semi-chemical pulping process, wherein raw materials are placed in a reactor with cooking chemical. The reactor is pressurized and heated. Typical chemicals for this process include sulfate and sulfite. Currently, the majority of Europe’s commercial wood cut goes to pulp, paper and board production. At the same time, the paper industry has a direct impact on deforestation and therefore a negative impact on the environment. The pulp and paper industry is rapidly growing, and paper demands are continuing to rise. It is therefore desired to find alternative raw materials.

Several alternative raw materials have been tested. For instance, waste streams from agricultural residues, fiber crops, wild plants and textile. Other tried alternatives include pineapple leaves, wheat grass, sugar cane bagasse, bamboo, and hemp (see i.a. Danielewicz et al. (2015) Grass pulp and paper, BioResources 10(4), 8552-8564, and Danielewicz et al. Cellulose (2017), 24:5173-5186).

Another example is provided in US2018/0105851. A method is described for preparing pulp for paper using grass straws as raw material. The method includes a first enzymolysis to obtain a first enzymolysis product. The product is cooked and subjected to a second enzymolysis.

In CN1267605 pulp is produced from wheat straw, straw or wood. Bacterial species are used to decompose lignin.

Another example is provided in CN104690066. Energy grass is used as a raw material from which pulp is made. The energy grass is subjected to fermentation. However, it is a time-consuming process, and during fermentation cellulose is degraded.

CN 109440514 describes a pulping method using straw, reed and grass straw as raw materials. Disadvantageously, the method requires a pyrolysis step.

The present inventors surprisingly found a method for producing a cellulose-containing pulp that overcomes at least part of the above-mentioned drawbacks. In particular, the method allows for minimal dependence on wood as a raw material, less intensive procedures on energy and chemicals compared to conventional pulp and/or paper production. The method further allows for the use of waste streams and minimizes transport.

Figure 1A and IB illustrate paper sheets of different compositions.

Figure 2 illustrates the tensile index of several paper sheets.

Figure 3 illustrates the results of chemical analysis of pulp obtained by a variety of protocols.

The present invention is accordingly directed to a method for preparing a cellulose-containing pulp that is suitable for paper production from gramineous material. The method comprises:

- a digestion step comprising reducing a sugar content and/or a protein content of a gramineous material to obtain a lean gramineous material;

- a treatment step comprising treating the lean gramineous material with a base solution to obtain a cellulose-containing pulp.

Gramineous material is herein used to describe a material that resembles a grass, is a grass or is grass-like. For instance, the gramineous material may comprise 50 wt.% or more of monocotyledon species, such as 60 wt.% or more or 70 wt.% or more, based on the total dry weight of the gramineous material. It may be appreciated that the gramineous material is optionally subjected to a pre-treatment step before performing the digestion step. This pre-treatment step may include removing any impurities, such as waste from road verges. As such, and in line with teachings in this disclosure, the gramineous material is typically a raw material, serving as a primary, unprocessed input for further processes like digestion or pre-treatment. The gramineous material may thus be in its harvested state, particularly without having undergone significant processing, such as precooking (sterilizing). Maintaining the raw, unprocessed, or minimally treated nature of the gramineous material surprisingly results in a cellulose-containing pulp that is ideally suited for the production of paper-based products while also allowing for less intensive use of energy compared to pulp production in the art.

Preferred gramineous material has a sugar content of 15 wt.% or less and/or a protein content of 25 wt.% or less. Preferably, the gramineous material has a low nutritional value. For instance, the gramineous material may have a sugar content of 10 wt.% or less and/or a protein content of 15 wt.% or less. It is noted that the weight percentages are based on the total dry weight of the gramineous material.

Several examples that may suitably be used include annual grass and perennial grass. Accordingly, it is preferred that the gramineous material comprises annual grass and/or perennial grass, preferably perennial grass. Annual grass is typically used to describe grasses that have a lifecycle in which the seed is important and may live less than one growing season. Perennial grass is typically used to describe grasses that have underground storage organs, like rhizomes, from which they may regrow. Often, perennial grass lives more than two years. Perennial grass may originate from grass from road verges and/or grass from nature land.

The roadside grass or nature land grass is typically cut or mowed and left to decay, or it may be composted. It was found that this grass is a cellulosic material that has a high potential for use in paper-based products. Furthermore, such grasses have a low lignin content. The grasses from the roadside or from the nature land thus provide good raw material alternatives to paper production. Accordingly, the method according to the present invention may be used to turn the low-quality grass from nature land and road verges into high-value products, such as paper.

The digestion step comprises reducing a sugar content and/or a protein content of the gramineous material. Digestion is known in the art, and is typically used to describe a process wherein multiple species of microorganisms break down compounds into smaller components. In contrast to digestion, fermentation is typically carried out by one specific species of microorganism. Unlike digestion processes in the art, the digestion step as described herein may typically result in at least methane being formed.

Reducing the sugar content and/or the protein content is believed to aid in i.a. the removal of lignin in later steps (vide infra). Typically, the gramineous material is a stalky network forming raw material. In order to suitably digest this material, it is preferred that the digestion step comprises dry digestion of the gramineous material. Dry digestion is a term that is known in the art. It is generally an anaerobic digestion process. Dry digestion is used to describe a digestion process at higher than 20% of total solid (TS) content (e.g. gramineous material) in the digestor tank. The input material is accordingly typically at least 20% solid matter. Dry digestion may be suitable for wastes with a high TS content, such as agricultural wastes. During dry digestion, a digestion fluid may be provided in the digestor tank such that it contacts and percolates through the solid material.

Accordingly, it is preferred that the digestion step comprises contacting the gramineous material with a digestion fluid. This digestion fluid typically comprises anaerobic microorganisms. Particularly suitable anaerobic microorganisms are methane-forming bacteria that may be selected from species of the genera Methanoculleos, such as M. hydrogenitrophicus; Moorella, such as M. glycerini; Xylanivirga, such as X. thermophila,- Candidatus, such as Ca. M. intestinalis; and/or Mahella, such as M. australiensis. Preferably, the anaerobic methane-forming bacteria comprises one or more species of the genera Methanoculleus, Moorella, and/or Xylanivirga. The digestion fluid may typically comprise at least one or more species of the genus Xylanivirga. It may be preferred that the digestion fluid further comprises water.

The inventors found that the use of methane-forming bacteria, in particular those mentioned in this disclosure, in the processing of gramineous material not only facilitates the production of biogas, but also surprisingly yields significant advantages in the preparation of cellulose-containing pulp from gramineous material. Specifically, they enhance the breakdown of the cell walls of the gramineous material, particularly non-cellulosic components, such as hemicellulose and lignin but also pectins and (structural) proteins, resulting in a more efficient separation of cellulose fibers. Consequently, the use of methane-forming bacteria reduces the overall need for harsh chemical treatments typically required in pulp production in the art, such as the use of strong alkalis or elevated temperatures of, e.g., 100°C or more. Therefore, the selective degradation of non-cellulosic matter combined with the reduction in chemical use and concurrent production of biogas as a valuable byproduct leads to a cellulose-containing pulp that can be more readily processed into paper-based products and thus provides a more sustainable and economically advantageous process.

In order to have a good digestion, it may be advantageous to provide the gramineous material and the digestion fluid in a particular ratio. Particularly good results were found if the weight ratio between the gramineous material and the digestion fluid is between 1 : 1 to 1 : 10, preferably 1 : 2 to 1 : 7, more preferably 1 : 2 to 1 : 5. Alternatively, the ratio may be expressed as a volume ratio. In such case, the volume ratio between the digestion fluid and the gramineous material may be between 1 : 1 to 1 : 10, preferably 1 : 3 to 1 : 7.

For instance, in the context of the present invention, the digestor tank may be an airtight, isolated and heated container and may comprise a separate storage unit to store the digestion fluid. The gramineous material may be provided in the container. The digestion fluid is typically introduced into the container by a sprinkler installation, thereby introducing the digestion fluid from the top and letting it drip and/or percolate through the gramineous material. By contacting the digestion fluid with the gramineous material, sugars and/or proteins may be at least partly broken down, thereby reducing the sugar content and/or the protein content of the gramineous material. The sugars and/or the proteins that are broken down may be converted into biogas, mainly comprising methane.

The biogas typically mainly comprises methane (CH4). However, it may be appreciated that the biogas may further comprise carbon dioxide (CO2), nitrogen (N2), hydrogen (H2), oxygen (O2), hydrogen sulfide (H2S), and/or optionally impurities.

The biogas is a suitable source of energy, i.e. heat. Accordingly, at least part of the biogas that may be formed during the digestion step, may suitably be used to provide heat to the digestion step and/or the treatment step. This allows to further improve the value creation. Alternatively, or additionally, the biogas may be collected.

In order to sufficiently lower the sugar content and/or the protein content, it may be preferred to keep at least part of the gramineous material in the digestion step for a particular amount of time. For instance, the digestion step may last 2-40 days, preferably 3-35 days, more preferably 4-30 days. Alternatively, this may be expressed in hours such that the digestion step preferably lasts 48-960 hours, preferably 72-840 hours, more preferably 96-720 hours.

In order to provide an optimal environment for the microorganisms, it is typically preferred to apply heat during the digestion step. Accordingly, the digestion step preferably comprises subjecting the gramineous material to a temperature of 30-80 °C, preferably 30-70 °C, more preferably 40-60 °C, such as 40-50 °C or 50-60 °C. Advantageously, it may not be required to apply a pressure.

The lean gramineous material is obtained from the digestion step. Generally, the lean gramineous material is obtained in a wet state, wherein some of the digestion fluid and some of the sugars and proteins (e.g. dissolved in the digestion fluid) are still present. Accordingly, it may be preferred that the method further comprises washing the lean gramineous material. This typically allows for removing the digestion fluid, sugar remains and/or protein remains from the lean gramineous material. Washing is preferably performed using water. This water may be recycled and reused.

In order to be able to produce a strong paper-based product, it may be preferred to open lignocellulose fiber bundles from the lean gramineous material such that the lignin degrades, and the remaining cellulose fibers can connect. Accordingly, the method further comprises a treatment step wherein the lean gramineous material is treated with a base solution. This typically allows for the fiber bundles to open and removal of lignin.

The base solution is typically used to increase the pH, for instance to a pH of 7 or more, such as 8-15 or 10-14. This pH may allow for the fiber bundles to open up and for lignin to degrade. The base solution is preferably an aqueous alkaline solution. This solution preferably has a pH of 7 or more, such as 8-15 or 10-14. A particularly suitable example is an aqueous solution of NaOH.

It may be appreciated that the concentration of the base solution and/or the ratio of the lean gramineous material to the base solution are not particularly limiting. The concentration and/or ratio are typically chosen such that the desired pH is achieved. For instance, a base solution having a concentration of 1-20 g/L of a base in water may be used, such as 10 g/L of NaOH in water. Dependent on the obtained pH, more water and/or more base solution with a higher or lower concentration NaOH may be added. Typically, a volume ratio of lean gramineous material to the base solution of 1 : 6 to 6 : 1 may be used, preferably 1 : 3 to 3 : 1, such as about 2 : 3.

In order to obtain sufficient treatment, it may be preferred that treatment of the lean gramineous material with the base solution lasts 1-10 hours, preferably 2-8 hours, such as 3-5 hours. Typically, the treatment step further comprises subjecting the lean gramineous material to a temperature of 95 °C or less, preferably 30-90 °C or 40-80 °C. Advantageously, it may not be required to apply a pressure.

Without wishing to be bound by theory, it is believed that reducing the sugar content and/or the protein content of the gramineous material allows for an easier removal of lignin. That is, the conditions under which the lean gramineous material is treated with a base solution, are less harsh than for a gramineous material with a higher sugar content and/or a higher protein content.

After the lean gramineous material has been contacted with the base solution, the pH of the lean gramineous material is typically such that it may not be safely handled (e.g. pH 13). Accordingly, it may be preferred that the lean gramineous material is contacted with an acidic solution after it was contacted with the base solution. Contacting the lean gramineous material with the acidic solution typically allows for lowering or neutralizing the pH (to approximately pH 7). Preferably, the acidic solution is an aqueous acidic solution, such as an aqueous solution comprising H2SO4. It is particularly preferred that the aqueous acidic solution has a pH lower than 6, such as between 1-5 or 1-3.

It may be appreciated that the base solution and/or the acidic solution may be recovered and/or reused.

Following the treatment step, the cellulose-containing pulp may be brought into a suitable size for industrial use, such as paper production. It may be appreciated that the suitable size is dependent on the final application. As an example, if the size is too small, it may be such that the structure is too dense, and water may not move through the pulp. This may reduce the final paper quality as the dewatering capacity is insufficient. If the size is too large, it may pollute the machines used for i.a. paper production, making it challenging to clean the machines and to switch between types of batches of paper production. Accordingly, the method preferably further comprises comprising cutting and/or crushing the cellulose-containing pulp.

The cellulose-containing pulp that is obtained after the treatment step or after the treatment step and cutting and/or crushing, may be stored and subsequently used in e.g. paper production.

Alternatively or additionally, the cellulose-containing pulp may be at least partly dried. The method therefore may further comprise at least partly drying the cellulose-containing pulp.

The present invention is further directed to the cellulose-containing pulp that is obtainable by the method described herein. It may be appreciated that this may be the cellulose-containing pulp obtained after the treatment step, after the cutting and/or crushing, and/or after at least partly drying the cellulose-containing pulp.

The cellulose-containing pulp may have a sugar content of 10 wt.% or less and/or a protein content of 15 wt.% or less, based on the total dry weight of the pulp. In particular, the sugar content may be 8 wt.% or less, such as 6 wt.% or less or 4 wt.% or less, and/or the protein content may be 13 wt.% or less, such as 11 wt.% or less or 9 wt.% or less. Preferably, the sugar content is 5 wt.% or less, such as 3 wt.% or less or 1 wt.% or less, e.g., 0-7 wt.% or 0.1-4 or 0.5-2 wt.%, and/or the protein content may be 10 wt.% or less, such as 7 wt.% or less or 5 wt.% or less, e.g., 0-8 wt.%, 0.1-6 wt.%, or 0.5-4 wt.%.

It was found that the cellulose-containing pulp has sufficient dewatering of the pulp, resulting in sufficient paper production speed such that it may be economically viable. Furthermore, the strength of the paper remains sufficient. Without wishing to be bound by theory, it is believed that this is due to reducing the sugar content and/or the protein content in the digestion step. Accordingly, the cellulose-containing pulp is particularly suitable for producing a paper-based substrate. Examples of paper-based substrates include, but are not limited to, a paper sheet, a cardboard and paper bags. Accordingly, the present invention is further directed to a method for producing a paper-based product, such as a paper sheet or a cardboard, wherein the method comprises producing a paper-based product comprising the cellulose-containing pulp.

It was found that a paper-based product may comprise a significant amount of the cellulose-containing pulp. It may be such that the amount of the cellulose-containing pulp in the paper-based product is 15 wt.% or more, preferably 30 wt.% or more, more preferably 50 wt.% or more, even more preferably 70 wt.% or more, based on the total dry weight of the paper-based product.

Even more surprisingly, it was found that the amount of the cellulose-containing pulp in the paper-based product may be 90 wt.% or more, based on the total dry weight of the paper-based product.

For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described.

The project leading to this application has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 862674.

The invention may further be illustrated by the following non-limiting examples.

Example 1

Six paper sheets were made with varying amounts of cellulose-containing pulp from gramineous material. Those papers are illustrated in Figures 1A and IB. The compositions of the papers are summarized in Table 1. Paper sheets D, E, and F were stained red. Table 1. Composition of produced paper sheets.

Example 2

Strips were cut from three paper sheets. The tensile index of the paper (Nm/g) was tested by pulling the strips (15 mm x 22 cm) until fracture (Low Force testing system, Instron, Norwood, Massachusetts, USA). The results are provided in Figure 2. In Figure 2, cellulose refers to a paper made of 100% wood-based cellulose (Ardennes) that was undigested (0 days digestion). The test strips consist of papers of 100% cellulose-containing pulp, which have been extracted from gramineous material with or without a digestion step, where digestion was performed at 37 °C, using a digestion fluid. The digestion fluid was made from digestate of Knijff Agro B.V. that was manually fed with maize for months. The protocols for the test strips were 0 days digestion and alkali treatment 10 g/L (D0days_10g/L), 0 days digestion and alkali treatment 20 g/L (D0days_20g/L), 7 days digestion and alkali treatment 10 g/L (D 7 day s_ 10 g/L), 7 days digestion and alkali treatment 20 g/L (D7days_20g/L). Each test strip group consisted of 3 to 5 strips (Figure 2 shows mean ± standard deviation)

Example 3

Laboratory chemical analysis was performed on pulp that was obtained by different protocols (n=l). The results are illustrated in Figure 3. The protocols were 0 days digestion and no alkali treatment (O.D.Oavg), 7 days digestion and no alkali treatment (O.D.7avg), 0 days digestion and alkali treatment 20 g/L (0.dd_20gl), 7 days digestion and alkali treatment 20 g/L (7.dd_20gl). The analyses showed (in g/kg pulp) the raw protein (RE, corr), sugar (Suiker, corr), acid detergent lignin (ADL, corr), and the intestinal digestive protein (DVE, corr).

Claims

1. Method for preparing a cellulose-containing pulp that is suitable for paper production from gramineous material, wherein the method comprises:

- a digestion step comprising reducing a sugar content and/or a protein content of a gramineous material to obtain a lean gramineous material; and

- a treatment step comprising treating the lean gramineous material with a base solution to obtain a cellulose-containing pulp, wherein the digestion step comprises contacting the gramineous material with a digestion fluid comprising anaerobic digestion microorganisms, said microorganisms being methane-forming bacteria, resulting in the formation of a biogas.

2. Method according to the previous claim, wherein based on the total dry weight of the gramineous material the sugar content is 15 wt.% or less and/or the protein content is 25 wt.% or less.

3. Method according to claim 1 or 2, wherein based on the total dry weight of the gramineous material the sugar content is 10 wt.% or less and/or the protein content is 15 wt.% or less.

4. Method according to any of the previous claims, wherein the gramineous material comprises annual grass and/or perennial grass, preferably perennial grass.

5. Method according to any of the previous claims, wherein the gramineous material comprises grass from road verges and/or grass from nature land.

6. Method according to any of the previous claims, wherein the digestion step comprises dry digestion of the gramineous material.

7. Method according to any of the previous claims, wherein the methane-forming bacteria comprises one or more species selected from the group consisting of the genera Methanoculleos, Moorella, Xylanivirga, Candidatus and Mahella, preferably Methanoculleus, Moorella and/or Xylanivirga.

8. Method according to claim 7, wherein the methane-forming bacteria comprises one or more species from the genus Xylanivirga.

9. Method according to claim 7 or 8, wherein a volume ratio between the digestion fluid and the gramineous material is between 1 : 1 to 1 : 10.

10. Method according to claim 9, wherein the volume ratio is in the range of 1 : 3 to 1 : 7.

11. Method according to any of the previous claims, wherein at least part of the formed biogas is used to provide heat to the digestion step and/or the treatment step.

12. Method according to any of the previous claims, wherein the digestion step lasts 2-40 days, preferably 3-35 days.

13. Method according to any of the previous claims, wherein the digestion step lasts 4-30 days.

14. Method according to any of the previous claims, wherein the digestion step comprises subjecting the gramineous material to a temperature of 30-80 °C, preferably 30-70 °C.

15. Method according to any of the previous claims, wherein the digestion step comprises subjecting the gramineous material to a temperature in the range of 40-60 °C.

16. Method according to any of the previous claims, further comprising washing the lean gramineous material.

17. Method according to any of the previous claims, wherein the base solution is an aqueous alkaline solution, preferably having a pH of 7 or more.

18. Method according to claim 17, wherein the base solution has a pH in the range of 8-15 or 10-14.

19. Method according to any of the previous claims, wherein the treating the lean gramineous material with the base solution lasts 1-10 hours, preferably 2-8 hours.

20. Method according to any of the previous claims, wherein the treating the lean gramineous material with a base solution lasts 3 to 5 hours.

21. Method according to any of the previous claims, wherein the treatment step comprises subjecting the lean gramineous material to a temperature of 95 °C or less, preferably in the range of 30-90 °C.

22. Method according to any of the previous claims, wherein the treatment step comprises subjecting the lean gramineous material to a temperature in the range of 40-80 °C.

23. Method according to any of the previous claims, further comprising cutting and/or crushing the cellulose-containing pulp.

24. Method according to any of the previous claims, further comprising at least partly drying the cellulose-containing pulp.

25. Cellulose-containing pulp obtainable by the method according to any of the previous claims.

26. Method for producing a paper-based product, such as a paper sheet or a cardboard, wherein the method comprises producing a paper-based product comprising the cellulose-containing pulp according to claim 25.

27. Paper-based product, such as a paper sheet or a cardboard, comprising an amount of the cellulose-containing pulp according to claim 25 of 15 wt.% or more, based on the total dry weight of the paper-based product, preferably 30 wt.% or more.

28. Paper-based product of claim 27, wherein the amount of the cellulose-containing pulp, based on the total dry weight of the paper-based product is 50 wt.% or more.

29. Paper-based product of claim 28, wherein the amount of the cellulose-containing pulp, based on the total dry weight of the paper-based product is 70 wt.% or more.

30. Paper-based product according to any one of claims 27-29, wherein the amount of the cellulose-containing pulp is 90 wt.% or more, based on the total dry weight of the paper-based product.