Method for producing cellulose-containing composition, method for producing cellulose nanofiber-containing composition, cellulose-containing composition, and cellulose nanofiber

Abstract

Provided is a method for producing a novel cellulose-containing composition that yields extremely fine cellulose nanofibers having, for example, an average fiber width of 100 nm or less and further an average fiber width of 10 nm or less by miniaturization treatment performed through a high-pressure homogenizer treatment without chemical modification and / or regeneration treatment.　This method for producing a novel cellulose-containing composition comprises a step for mixing a biomass containing lignocellulose as a component (A), a peroxide and / or a peracid as a component (B), and at least one of an acid and a compound represented by the following formula (c-1) as a component (C), and delignifying the lignocellulose (in formula (c-1), a ring Z represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring, R7 represents a divalent hydrocarbon group, m represents an integer of 0 or grearter, and n represents an integer of 1 or greater), the acid in the component (C) having an acid dissociation constant (pKa) of −7.5 < pKa < −0.4.

Description

Method for producing cellulose-containing composition, method for producing cellulose nanofiber-containing composition, cellulose-containing composition and cellulose nanofiber

[0001] The present disclosure relates to a method for producing a cellulose-containing composition, a method for producing a cellulose nanofiber-containing composition, a cellulose-containing composition, and a cellulose nanofiber.

[0002] The cell walls of trees, herbs, etc. are mainly composed of lignocellulose (i.e., a structure in which polysaccharides including cellulose and hemicellulose are bound to lignin), which are the most abundant natural polymers on earth.

[0003] It is conceivable that polysaccharides such as cellulose and lignin can be separated, recovered, and utilized from biomass containing lignocellulose, such as from trees and herbs.

[0004] An example of an application of cellulose is cellulose nanofibers. Cellulose nanofibers are nano-sized fibrous cellulose with a diameter of approximately 1 to 100 nm and a length 100 times or more the diameter. Cellulose nanofibers have properties such as high strength, low thermal expansion, transparency, a large specific surface area, biodegradability, and biocompatibility, and as a plant-derived material, they have a low environmental impact, so much research and development is being conducted on them. Note that the cellulose nanofibers referred to here also include those that contain small amounts of components other than cellulose (e.g., hemicellulose and lignin).

[0005] In biomass containing lignocellulose, cellulose forms a complex with lignin. Therefore, in order to extract cellulose from biomass containing lignocellulose, it is first necessary to decompose and remove the lignin from the lignocellulose.

[0006] For example, Patent Document 1 describes a method for producing dissolving pulp by delignifying lignocellulose through hydrolysis-alkali cooking treatment.

[0007] Furthermore, in order to obtain cellulose nanofibers from cellulose obtained by delignification of biomass containing lignocellulose, it is necessary to pulverize the cellulose to the cellulose nanofiber level.

[0008] Japanese Patent Application Laid-Open No. 2013-227705

[0009] Various methods are known for obtaining cellulose by decomposing and removing lignin from lignocellulose, but conventional methods for decomposing and removing lignin from lignocellulose require the application of a large amount of energy, making them difficult to accomplish.

[0010] Furthermore, when cellulose from which lignin has been removed by applying a large amount of energy is further refined, a large amount of energy must also be applied. If the energy application is insufficient, the average fiber width of the resulting cellulose nanofibers will exceed 100 nm, and even if a large amount of energy is applied, it is difficult to obtain cellulose nanofibers that have been refined to an average fiber width of, for example, 10 nm or less.

[0011] Furthermore, there is a method for obtaining cellulose nanofibers without applying a large amount of energy by chemically modifying (chemically denaturing) the cellulose obtained by decomposing lignin from lignocellulose and then pulverizing the cellulose to obtain cellulose nanofibers using special chemicals such as TEMPO (2,2,6,6-tetramethylpiperidine 1-oxyl). However, methods that promote pulverization by chemically modifying cellulose have various problems, such as (i) changes in the physical properties of the cellulose nanofibers that are ultimately obtained, (ii) the need for the use of special chemicals, and (iii) impurities resulting from the chemical modification remaining in the cellulose nanofibers. These problems can also occur when chemically modified cellulose nanofibers are regenerated (processed to return them to unmodified cellulose nanofibers).

[0012] Therefore, the inventors of the present disclosure have undertaken a novel problem-solving effort to develop cellulose nanofibers (CNFs) that do not require the application of large amounts of energy, have not been subjected to chemical modification and / or regeneration treatment, and have been refined to an average fiber width of 10 nm or less.

[0013] An object of the present disclosure is to provide a novel method for producing a cellulose-containing composition that can produce extremely fine cellulose nanofibers, for example, with an average fiber width of 100 nm or less, or even 10 nm or less, by micronization, for example, using a high-pressure homogenizer, without chemically modifying and / or regenerating lignocellulose-containing biomass. Another object of the present disclosure is to provide a novel method for producing a cellulose nanofiber-containing composition, in which cellulose nanofibers are obtained by micronizing the cellulose-containing composition obtained by the cellulose-containing composition production method. A further object of the present disclosure is to provide a novel cellulose-containing composition that can be produced using the cellulose-containing composition production method of the present disclosure, and a novel cellulose nanofiber that can be produced using the cellulose-containing composition production method of the present disclosure.

[0014] The inventors of the present disclosure conducted extensive research to solve the above-mentioned problems, and as a result, they discovered that by mixing lignocellulose-containing biomass with a peroxide and / or a peracid, and at least one of a specified acid and a specified compound, and delignifying the lignocellulose, a novel cellulose-containing composition can be obtained that provides extremely fine cellulose nanofibers, for example, with an average fiber width of 100 nm or less, or even 10 nm or less, by a minor refining treatment using a high-pressure homogenizer, without chemical modification and / or regeneration treatment.

[0015] Furthermore, the inventors of the present disclosure have discovered that by mixing biomass containing lignocellulose, a peroxide and / or peracid, an acid different from the peroxide and peracid, and a specified solvent and delignifying the lignocellulose, a novel cellulose-containing composition can be obtained that gives extremely fine cellulose nanofibers, for example, with an average fiber width of 100 nm or less, or even 10 nm or less, by a minor refining treatment using a high-pressure homogenizer, without chemical modification and / or regeneration treatment.

[0016] The present disclosure has been completed based on these findings and further investigations. That is, the present disclosure provides the inventions of the following aspects.

[0017] Item 1. A method for delignifying lignocellulose, comprising the steps of mixing lignocellulose-containing biomass as component (A), a peroxide and / or peracid as component (B), at least one of an acid and a compound represented by the following formula (c-1) as component (C), and a solvent as component (E), [In the formula (c-1), ring Z represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring, and R 7 represents a divalent hydrocarbon group, m represents an integer of 0 or more, and n represents an integer of 1 or more.] Item 2. A method for producing a cellulose-containing composition, wherein the acid in component (C) is an acid having an acid dissociation constant (pKa) of -7.5<pKa<-0.4. Item 3. A method for producing a cellulose-containing composition, comprising a step of mixing a biomass containing lignocellulose as component (A), a peroxide and / or peracid as component (B), an acid different from the peroxide and the peracid as component (D), and a solvent as component (E) to delignify the lignocellulose, wherein the solvent as component (E) is an acid having an octanol / water partition coefficient (logP オクタノール / 水 Item 3. A method for producing a cellulose-containing composition, wherein the component (C) and the component (D) are solvents having a toluene / water partition coefficient (logP) of the acid of 0.5 or more, or at least one solvent selected from the group consisting of hydrocarbon solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, and ester solvents.トルエン / 水Item 4. The method for producing a cellulose-containing composition according to any one of Items 1 to 3, wherein the delignification step is carried out at a temperature of 100°C or less. Item 5. The method for producing a cellulose-containing composition according to any one of Items 1 to 4, further comprising a step of separating a suspension containing the cellulose-containing composition produced in the delignification step into a phase containing cellulose as a main solid content and a phase derived from the biomass and solubilized or liquefied in a solvent. Item 6. The method for producing a cellulose-containing composition according to any one of Items 1 to 5, wherein the average fiber width of cellulose-containing fibers contained in the cellulose-containing composition is 1 μm or more. Item 7. The method for producing a cellulose-containing composition according to any one of Items 1 to 6, further comprising one or more steps of esterifying, etherifying, azidizing, or amminating a portion of the hydroxyl groups of the cellulose contained in the cellulose-containing composition in the delignification step or a subsequent step. Item 8. Item 9. A method for producing a cellulose nanofiber-containing composition, comprising a step of subjecting the cellulose-containing composition obtained by the method for producing a cellulose-containing composition according to any one of Items 1 to 7 to a micronization treatment until the average fiber width of the cellulose-containing fibers contained in the cellulose-containing composition is 100 nm or less, thereby obtaining cellulose nanofibers. Item 10. A method for producing a cellulose nanofiber-containing composition according to Item 8, wherein the average fiber width of the cellulose nanofibers is 10 nm or less. Item 10. A method for producing a cellulose nanofiber-containing composition according to Item 8 or 9, wherein the micronization treatment is carried out using a high-pressure homogenizer. Item 11. A method for producing a cellulose nanofiber-containing composition according to any one of Items 8 to 10, wherein the cellulose nanofibers are produced without chemically modifying the cellulose. Item 12. A cellulose-containing composition that, when subjected to high-pressure homogenizer treatment under the following conditions, produces cellulose nanofibers with an average fiber width of 100 nm or less after 10 or fewer treatments, or that, when made into an aqueous dispersion with a solids concentration of 0.1% by mass, produces cellulose nanofibers with a light transmittance of 50% or more as measured using a spectrophotometer at a wavelength of 660 nm and an optical path length of 1 cm.(Conditions for High-Pressure Homogenizer Treatment) The cellulose-containing composition to be subjected to high-pressure homogenizer treatment is an aqueous dispersion having a solids concentration of 0.3 to 1.0% by mass. The treatment pressure is within the range of 150 to 245 MPa, the nozzle diameter is 0.1 to 0.15 mm, the treatment temperature is 25°C ± 25°C, and the number of treatments is 10 or less. Item 13. A cellulose-containing composition that, when subjected to high-pressure homogenizer treatment under the following conditions, produces cellulose nanofibers having an average fiber width of 100 nm or less after 10 or fewer treatments, or, when made into an aqueous dispersion having a solids concentration of 0.1% by mass, produces cellulose nanofibers having a light transmittance of 50% or more as measured using a spectrophotometer at a wavelength of 660 nm and an optical path length of 1 cm. (Conditions for High-Pressure Homogenizer Treatment) The cellulose-containing composition to be subjected to high-pressure homogenizer treatment is an aqueous dispersion having a solids concentration of 0.3 to 1.0% by mass. The treatment pressure is 100 MPa, the nozzle diameter is 0.1 to 0.15 mm, the treatment temperature is 25°C ± 25°C, and the number of treatments is 10 or less. Item 14. The cellulose-containing composition according to Item 12 or 13, wherein the average fiber width of the cellulose-containing fibers contained in the cellulose-containing composition is 1 μm or more and 100 μm or less. Item 15. The cellulose-containing composition according to any one of Items 12 to 14, wherein the average fiber width of the cellulose nanofibers is 10 nm or less. Item 16. The cellulose-containing composition according to any one of Items 12 to 15, wherein the cellulose contained in the cellulose-containing composition has not been chemically modified and / or regenerated. Item 17. The cellulose-containing composition according to any one of Items 12 to 16, wherein the cellulose has a weight-average molecular weight of 200,000 or more. Item 18. Cellulose nanofibers that have not been chemically modified and / or regenerated and have an average fiber width of 10 nm or less. Item 19. A cellulose nanofiber that has not been chemically modified and / or regenerated, and when dispersed in water with a solids concentration of 0.1% by mass, has a light transmittance of 50% or more as measured using a spectrophotometer at a wavelength of 660 nm and an optical path length of 1 cm.

[0018] According to the present disclosure, there is provided a novel method for producing a cellulose-containing composition, which provides extremely fine cellulose nanofibers, for example, with an average fiber width of 100 nm or less, or even 10 nm or less, by minor micronization treatment, for example, by high-pressure homogenization, without chemically modifying and / or regenerating lignocellulose-containing biomass. Furthermore, according to the present disclosure, there is also provided a novel method for producing a cellulose nanofiber-containing composition, in which the cellulose-containing composition obtained by the cellulose-containing composition production method is micronized to obtain cellulose nanofibers. Furthermore, there are provided a novel cellulose-containing composition that can be produced using the cellulose-containing composition production method of the present disclosure, and a novel cellulose nanofiber that can be produced using the cellulose-containing composition production method of the present disclosure.

[0019] 1 is a fluorescence microscope photograph of cellulose-containing composition A before treatment with a high-pressure homogenizer in Example 1.

[0033] FIG. 1 is a photograph of cellulose-containing composition A before treatment with a high-pressure homogenizer in Example 1.

[0034] FIG. 1 is an AFM image and width measurement example of the pulverized product of cellulose-containing composition A (treated twice) obtained in Example 1.

[0035] FIG. 1 is an AFM image of the pulverized product of cellulose-containing composition A (treated 10 times) obtained in Example 2.

[0036] FIG. 1 is a result of ATR-IR measurement performed on dried cellulose-containing composition A.

[0037] FIG. 1 is a result of solid-state 13C-NMR measurement performed on dried cellulose-containing composition A.

[0038] FIG. 1 is a photograph showing the viscosity behavior of aqueous dispersions (Examples 1 and 2) obtained by treating cellulose-containing composition A with a high-pressure homogenizer.

[0039] FIG. 2 is an X-ray diffraction diagram and crystallinity evaluation results of the pulverized product obtained by treating cellulose-containing composition A with a high-pressure homogenizer.

[0039] FIG. 2 is a fluorescence microscope observation image of the pulverized product of cellulose-containing composition A in Example 6 and the pulverized products of commercially available pulps (1) and (2) in Comparative Examples 1 and 2 (scale bar is 50 μm).

[0033] Water was added to the finely divided cellulose-containing composition A of Example 6, the finely divided commercially available pulps (1) and (2) of Comparative Examples 1 and 2, and the finely divided cellulose-containing composition B (bone dry) of Example 7, to prepare 0.1 wt% dispersions, and the transmittance was measured.

[0034] Figure 1 shows an AFM image of the finely divided cellulose-containing composition B of Example 7, which was subjected to two-pass or ten-pass processing.

[0035] Figure 1 shows an AFM image of the finely divided cellulose-containing composition C (processed 10 times) obtained in Example 8.

[0036] Figure 1 shows an AFM image of the finely divided cellulose-containing composition (processed 10 times) obtained in Example 9.

[0037] Figure 1 shows a graph plotting the results of measuring the amount of lignin remaining in the obtained cellulose composition (% vs. bone dry weight of raw cedar wood flour) against the acid dissociation constant (pKa) of the acid used in Reference Data 1. In Reference Data 2, the amount of lignin remaining in the obtained cellulose composition (% relative to the bone dry weight of raw cedar wood flour) was measured, and the result was compared with the toluene / water partition coefficient (log P トルエン / 水 In Reference Data 3, the amount of lignin remaining in the obtained cellulose composition (% relative to the bone dry weight of the raw material cedar wood flour) was measured, and the results were plotted against the octanol / water partition coefficient (logP オクタノール / 水In Reference Data 4, the amount of lignin remaining in the obtained cellulose composition (% relative to the bone dry weight of the raw material cedar wood flour) was measured, and the results were plotted against the octanol / water partition coefficient (logP オクタノール / 水 ) is a graph plotted against the transmittance. Example 10: Micronized cellulose-containing composition A (100 MPa treatment), Example 6: Micronized cellulose-containing composition A (200 MPa treatment), Comparative Example 1 and Comparative Example 2: Commercially available pulps (1) and (2) (200 MPa treatment, respectively). Water was added to each of these to prepare a 0.1 wt% dispersion, and the transmittance was measured. Example 11: Micronized cellulose-containing composition E (200 MPa treatment), Example 6: Micronized cellulose-containing composition A (200 MPa treatment), Comparative Example 1 and Comparative Example 2: Commercially available pulps (1) and (2) (200 MPa treatment, respectively). Water was added to each of these to prepare a 0.1 wt% dispersion, and the transmittance was measured.

[0020] The configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible as appropriate within the scope of the gist of the present disclosure. The present disclosure is not limited to the embodiments.

[0021] In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, separately described upper and lower limits, upper and lower limits, or lower and lower limits may be combined to form a numerical range. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.

[0022] [Method for producing cellulose-containing composition] A method for producing a cellulose-containing composition according to a first aspect of the present disclosure includes a step of mixing biomass containing lignocellulose as component (A), a peroxide and / or peracid as component (B), and at least one of an acid and a compound represented by the following formula (c-1) as component (C), and delignifying the lignocellulose, wherein the acid in component (C) is an acid having an acid dissociation constant (pKa) of −7.5<pKa<−0.4:

[0023]

[0024] In formula (c-1), ring Z represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring, and R 7 represents a divalent hydrocarbon group, m represents an integer of 0 or more, and n represents an integer of 1 or more.

[0025] By being provided with this configuration, the production method according to the first aspect of the present disclosure can produce a cellulose-containing composition that provides extremely fine cellulose nanofibers, for example, with an average fiber width of 100 nm or less, or even 10 nm or less, by minor micronization treatment, for example, using a high-pressure homogenizer, without chemically modifying and / or regenerating biomass containing lignocellulose.

[0026] Furthermore, a method for producing a cellulose-containing composition according to a second aspect of the present disclosure includes a step of mixing biomass containing lignocellulose as component (A), a peroxide and / or peracid as component (B), an acid different from the peroxide and the peracid as component (D), and a solvent as component (E) to delignify the lignocellulose, wherein the solvent as component (E) has an octanol / water partition coefficient (logP オクタノール / 水 ) is 0.5 or more, or is at least one solvent selected from the group consisting of hydrocarbon solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, and ester solvents.

[0027] By being provided with this configuration, the production method according to the second aspect of the present disclosure, like the production method according to the first aspect of the present disclosure, can produce a cellulose-containing composition that gives extremely fine cellulose nanofibers, for example, with an average fiber width of 100 nm or less, or even 10 nm or less, by minor micronization treatment, for example, using a high-pressure homogenizer, without chemically modifying and / or regenerating biomass containing lignocellulose.

[0028] The method for producing the cellulose-containing composition of the present disclosure will be described in detail below. In the following description, matters common to the cellulose-containing compositions according to the first and second aspects of the present disclosure will be described as descriptions relating to the present disclosure, and matters specific to the first and second aspects of the present disclosure will be clearly stated as descriptions relating to the first and second aspects of the present disclosure, respectively.

[0029] (Component (A)) In the method for producing a cellulose-containing composition of the present disclosure, component (A) is biomass containing lignocellulose. Lignocellulose is composed of a structure in which polysaccharides including cellulose and / or hemicellulose are bound or complexed with lignin, and a composition mainly composed of cellulose can be obtained by delignifying the lignocellulose.

[0030] Polysaccharides containing cellulose and / or hemicellulose are, for example, cell wall polysaccharides that mainly contain cellulose and hemicellulose.

[0031] Cellulose is a polysaccharide that forms the backbone of plant cell walls and is composed of [CH 10 O5] are polymers in which glucose-derived structural units are linked in a linear chain via β-(1-4) bonds. In plant cell walls, several dozen cellulose molecules, for example 18 molecules, are bundled to form microfibrils, and multiple microfibrils then associate in a rope-like fashion to form microfibril bundles.

[0032] The cellulose content of the polysaccharide varies depending on the type of plant used as the raw material. When cotton linter is used as the raw material, the cellulose content is, for example, 97% by weight or more. When paper pulp is used as the raw material, the cellulose content is, for example, 70 to 90% by weight.

[0033] Hemicellulose is a general term for polysaccharides other than cellulose, which crosslink microfibrils. Hemicellulose is composed of monosaccharides such as xylose, arabinose, mannose, and galactose, and has the effect of increasing the strength of cell walls by crosslinking cellulose microfibrils to form a mesh structure.

[0034] Lignin is a polymeric compound in which a three-dimensional network structure is formed by the high degree of polymerization of phenolic compounds (for example, cinnamyl alcohol, coniferyl alcohol, p-coumaryl alcohol, etc.).

[0035] From the viewpoint of more suitably exerting the effects of the present invention, the lignocellulose used as a raw material in the method for producing a cellulose-containing composition of the present disclosure is preferably a complex of lignin, cellulose, and hemicellulose, and particularly preferably a structure in which cellulose is bound to lignin via hemicellulose.

[0036] Biomass containing lignocellulose includes woody biomass including woody plants and processed products thereof, and herbaceous biomass including herbaceous plants and processed products thereof.

[0037] Specific examples of biomass containing lignocellulose that can be used include cut or crushed materials (e.g., chips, sawdust, etc.) of at least one plant selected from wood (coniferous trees such as cedar, broad-leaved trees such as eucalyptus, etc.), seed hairs (cotton linters, bombax cotton, kapok, etc.), gin bark (e.g., hemp, mulberry paper, mitsumata, etc.), and leaves (e.g., Manila hemp, New Zealand hemp, etc.). In particular, wood is a preferred embodiment because the present invention can be applied to wood containing a large amount of lignin. Furthermore, the present invention can also be applied to coniferous trees, which are considered difficult to delignify by delignification methods. Furthermore, the present invention can also be applied to wood from which it is considered difficult to produce cellulose nanofibers, so wood is a preferred embodiment. Furthermore, the present invention can also be applied to coniferous trees, which are considered difficult to produce cellulose nanofibers by delignification methods.

[0038] (Component (B)) In the method for producing a cellulose-containing composition of the present disclosure, component (B) is a peroxide and / or a peracid. Peroxides and peracids have a delignification effect (i.e., the effect of oxidizing and / or decomposing lignin in lignocellulose-containing biomass to release polysaccharides, particularly cellulose, from the complex).

[0039] The peroxide may be a compound represented by the following formula (3): 11 -O-O-R 12 (3)

[0040] In formula (3), R 11 and R 12 are the same or different and represent a hydrogen atom, a monovalent hydrocarbon group, or an acyl group (RCO group; R is a monovalent hydrocarbon group).

[0041] The monovalent hydrocarbon group includes a monovalent aliphatic hydrocarbon group, a monovalent alicyclic hydrocarbon group, a monovalent aromatic hydrocarbon group, and a monovalent group formed by combining these groups.

[0042] Of the monovalent hydrocarbon groups, monovalent aliphatic hydrocarbon groups, monovalent aromatic hydrocarbon groups, and monovalent groups in which two or more of the above groups are bonded are preferred.

[0043] The monovalent aliphatic hydrocarbon group is preferably an aliphatic hydrocarbon group having 1 to 20 carbon atoms, and particularly preferably a linear or branched alkyl group having 1 to 20 carbon atoms (preferably 1 to 10, and particularly preferably 1 to 5).

[0044] The monovalent aromatic hydrocarbon group is preferably an aryl group having 6 to 14 carbon atoms (preferably 6 to 10 carbon atoms), such as a phenyl group or a naphthyl group.

[0045] As the monovalent group formed by bonding two or more groups selected from monovalent aliphatic hydrocarbon groups and monovalent aromatic hydrocarbon groups, an aralkyl group having 7 to 10 carbon atoms, such as a benzyl group, is preferred.

[0046] The peroxide includes, for example, hydrogen peroxide (a compound represented by formula (3), where R 11 , R 12 represents a hydrogen atom); hydroperoxides such as t-butyl hydroperoxide and benzyl hydroperoxide (compounds represented by formula (3), 11 represents a monovalent hydrocarbon group, and R 12 represents a hydrogen atom); peroxides such as di-t-butyl peroxide and benzoyl peroxide (compounds represented by formula (3), 11 , R 12 and the like may be the same or different and each represents a monovalent hydrocarbon group or an acyl group).

[0047] Examples of peracids include organic peracids such as percarboxylic acids (e.g., performic acid, peracetic acid, trifluoroperacetic acid, perbenzoic acid, metachloroperbenzoic acid, monoperoxyphthalic acid, etc.); and inorganic peracids such as permanganic acid. These may be used alone or in combination of two or more.

[0048] From the viewpoint of more suitably exerting the effects of the present invention, the amount of peroxide or peracid used (the total amount when a peroxide and a peracid are used in combination) is, for example, 2 equivalents or more, preferably 3 equivalents or more, more preferably 10 equivalents or more, and particularly preferably 20 equivalents or more per monomer unit of lignin contained in lignocellulose-containing biomass. The upper limit of the amount of peroxide or peracid used is, for example, 30 equivalents, preferably 25 equivalents.

[0049] The amount of peroxide or peracid used (or the total amount when a peroxide and a peracid are used in combination) can be varied depending on the amount of lignin contained in the lignocellulose-containing biomass, from the viewpoint of more optimally achieving the effects of the present invention. For example, the amount is 0.2 to 10.0 mmol, preferably 0.5 to 5.0 mmol, more preferably 1.0 to 5.0 mmol, particularly preferably 2.0 to 5.0 mmol, and most preferably 2.0 to 4.0 mmol per 100 mg of lignocellulose. When the amount of peroxide or peracid used is within the above range, the oxidation and / or decomposition reaction of lignin in the lignocellulose-containing biomass proceeds rapidly in conjunction with component (C), component (D), or component "E" described below, thereby promoting delignification of the lignocellulose-containing biomass and resulting in a cellulose-containing composition with extremely low residual lignin. Furthermore, by suppressing excessive decomposition of cellulose, a cellulose-containing composition containing cellulose of an appropriate molecular weight can be obtained. As a result, a cellulose composition is obtained that is easily pulverized by pulverization treatment to give cellulose nanofibers with small widths.

[0050] (Component (C)) Component (C) is a component used in the method for producing a cellulose-containing composition according to the first aspect of the present disclosure, and is at least one of an acid and a compound represented by formula (c-1).

[0051] Component (C) preferably reacts with component (B) (peroxide or peracid) to produce a component (C)-derived peroxide. The resulting component (C)-derived peroxide then exhibits the effect of promoting the progress of the delignification reaction. This is presumably due to the high activity and / or affinity of the (C)-derived peroxide with lignin. Furthermore, the oxides and / or decomposition products of lignin produced by the delignification reaction are released from lignocellulose and dissolve in a solvent (e.g., water, an organic solvent, etc.) as component (E), which will be described later. Therefore, component (C) promotes the dissolution of lignin and lignin-derived components in the solvent.

[0052] The acid used as component (C) in the method for producing a cellulose-containing composition according to the first aspect of the present disclosure has an acid dissociation constant (pKa) in the range of -7.5<pKa<-0.4. That is, using an acid with a certain level of acidity can effectively decompose and elute lignin. However, the stronger the acidity, the higher the delignification effect is not necessarily. In the method for producing a cellulose-containing composition according to the first aspect of the present disclosure, the specific acid is used in combination with component (B) and component (E), thereby effectively delignifying biomass containing lignocellulose. Furthermore, it is possible to produce a novel cellulose-containing composition that can be refined by high-pressure homogenizer treatment to produce extremely fine cellulose nanofibers, for example, with an average fiber width of 100 nm or less, or even 10 nm or less, without chemical modification and / or regeneration treatment.

[0053] The acid used as component (C) in the method for producing a cellulose-containing composition according to the first aspect of the present disclosure has an acid dissociation constant (pKa) of, for example, −0.4 or less, preferably −0.6 or less, more preferably −2.0 or less, and particularly preferably −2.8 or less, and the lower limit is −7.5 or more, preferably −7.0 or more, and more preferably −6.0 or more. A preferred range is −7.0 to −0.6.

[0054] The dissociation constant (pKa) is determined from the reference: Ripin, D. H.; Evans, D. A. Evans pKa Table, http: / / ccc.chem.pitt.edu / wipf / MechOMs / evans_pKa_table.pdf (accessed August 22, 2024) or Williams, R; https: / / organicchemistrydata.org / hansreich / resources / pka / pka_data / pka-compilation-williams.pdf. For values ​​not found in these literature, calculations are performed using the method described in Ding, F.; Smith, J. M.; Wang, H. J. Org. Chem. 2009, 74, 2679-2691. For HB, which serves as the basis for pKa, the literature value for methanesulfonic acid, acetic acid, or benzoic acid is used. The temperature (T) is set to 298 K for calculations.

[0055] Furthermore, the component (C) used in the method for producing a cellulose-containing composition according to the first aspect of the present disclosure may be a compound represented by the following formula (c-1): It is also preferable to use, as the component (C), a compound represented by the following formula (c-1) and which is the specific acid.

[0056]

[0057] In the formula (c-1), ring Z represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring, and R 7 represents a divalent hydrocarbon group, m represents an integer of 0 or more, and n represents an integer of 1 or more.

[0058] Examples of the aromatic hydrocarbon ring in ring Z include aromatic hydrocarbon rings having 6 to 14 carbon atoms, such as a benzene ring, a naphthalene ring, and an anthracene ring. A 3- to 8-membered cycloalkane ring may be fused to the aromatic hydrocarbon ring. A 3- to 8-membered cycloalkane ring may be fused to the aromatic hydrocarbon ring.

[0059] Examples of the aromatic heterocycle for ring Z include a 3- to 10-membered (preferably 4- to 6-membered) aromatic heterocycle having at least one heteroatom, and a fused ring formed by fusing a 3- to 8-membered cycloalkane ring to the aromatic heterocycle. Specific examples include pyrrole, furan, thiophene, phosphole, pyrazole, imidazole, oxazole, isoxazole, thiazole, indole, benzofuran, benzothiophene, isoindole, isobenzofuran, benzophosphole, benzimidazole, benzoxazole, benzothiazole, benzisoxazole, indazole, benzisothiazole, benzotriazole, purine, pyridine, phosphinine, pyrimidine, pyrazine, pyridazine, triazine, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine, 1,2,3,5-tetrazine, hexazine, quinoline, isoquinoline, quinoxaline, quinazoline, cinnoline, pteridine, phthalazine, acridine, 4aH-phenoxazine, and carbazole.

[0060] The R 7 The divalent hydrocarbon group in is preferably a divalent (saturated) aliphatic hydrocarbon group, particularly preferably an alkylene group having 1 to 10 carbon atoms, and most preferably an alkylene group having 1 to 7 carbon atoms.

[0061] Examples of the compound represented by formula (c-1) in which ring Z is an aromatic hydrocarbon ring include benzenesulfonic acid; toluenesulfonic acids such as p-toluenesulfonic acid; and naphthalenesulfonic acids such as 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, 1,5-naphthalenedisulfonic acid, and 2-naphthylmethanesulfonic acid.

[0062] Examples of the compound represented by formula (c-1) above, in which ring Z is an aromatic heterocycle, include compounds represented by formula (c-1-1) or (c-1-2) below. In the following formula, ring Z' represents an aromatic heterocycle having a nitrogen atom as a heteroatom. R 7 , X - , Y - , m, and n are the same as above.

[0063]

[0064]

[0065] Preferred examples of the compound represented by formula (c-1) above, in which ring Z in the formula is an aromatic heterocycle, include compounds represented by the following formula (c-1-3), such as 1-methyl-3-(3-sulfopropyl)imidazolium p-toluenesulfonate; and compounds represented by the following formula (c-1-4), such as 2-(3-(2-sulfoethyl)-1H-imidazol-1-yl)ethanesulfonate.

[0066]

[0067] In the formulas (c-1-3) and (c-1-4), R 2 ~R 5 are the same or different and represent a hydrogen atom or a monovalent hydrocarbon group. R represents a divalent hydrocarbon group. X - represents a counter anion, and Y - represents an anionic group. 7 represents a divalent hydrocarbon group, and m represents an integer of 0 or more.

[0068] In the formula (c-1-3) and the formula (c-1-4), R 2 ~R 6 , X - , Y - R in the above formulas (b-1) and (b-2) 2 ~R 6 , X - , Y - Similar examples include:

[0069] The R 2 , R 4 , and R 6 is preferably a hydrogen atom.

[0070] Of the sulfonic acids, aromatic sulfonic acids are preferred because they have a particularly excellent delignification effect.

[0071] Examples of the phosphonic acids include aliphatic phosphonic acids such as methylphosphonic acid; and aromatic phosphonic acids such as phenylphosphonic acid.

[0072] Examples of the phosphinic acid include aliphatic phosphinic acids such as dimethylphosphinic acid; and aromatic phosphinic acids such as diphenylphosphinic acid.

[0073] From the viewpoint of more suitably exerting the effects of the invention of the present disclosure, the component (C) is preferably a sulfonic acid or sulfuric acid, particularly preferably a sulfonic acid, and most preferably an aromatic sulfonic acid.

[0074] In order to more suitably exert the effects of the present invention, the component (C) may further contain a toluene / water partition coefficient (logP トルエン / 水 ) is, for example, -5.4 or more, preferably -2.8 or more, more preferably -2.4 or more, even more preferably -2.2 or more, and particularly preferably -2.0 or more. In other words, when an acid having a high hydrophobicity to a certain extent is used, it has a high affinity for lignin, and therefore can effectively decompose and elute lignin. The toluene / water partition coefficient (logP トルエン / 水 ) is preferably within a range that allows component (C) to be well contacted and mixed with component (B). For example, when component (B) is present as an aqueous solution, component (C) is preferably soluble or dispersible in the aqueous solution.

[0075] Toluene / water partition coefficient of the acid (log P トルエン / 水 ) is calculated using the method of K. Kodama, et al. J. Comput. Chem. Jpn. 2019, 18, 241-243. The solvent in the literature is changed from octanol to toluene. The temperature (T) is calculated at 298 K.

[0076] Toluene / water partition coefficient (log P トルエン / 水 ) is -2.8 or more, for example, p-toluenesulfonic acid, naphthalenesulfonic acid, anthraquinonesulfonic acid, hexylbenzenesulfonic acid, dodecylsulfonic acid, etc. The acid used in the method for producing a cellulose-containing composition according to the first or second aspect of the present disclosure may be one type only, or two or more types.

[0077] In the present disclosure, the solvent of component (E) is selected from those having an octanol / water partition coefficient (logP オクタノール / 水 ) is a solvent having a toluene / water partition coefficient (logP) of 0.5 or more, or when at least one solvent selected from the group consisting of hydrocarbon solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, and ester solvents is not used, for example, when the solvent is water, the toluene / water partition coefficient (logP) is 0.5 or more, as component (C), compared to when these solvents are used. トルエン / 水 ) is preferred.

[0078] In addition, if component (C) penetrates into the biomass structure, for example, the cell walls of the biomass, and has easy access to lignin, it is easy to obtain a delignification effect. Therefore, it is preferable that component (C) has a size and shape that allows it to easily pass through the pores of the target biomass.

[0079] The amount of component (C) used (the total amount when two or more types of component (C) are used) can be appropriately changed depending on the type of component (C), but is, for example, 0.001 to 1.0 mmol, preferably 0.005 to 0.5 mmol, and preferably 0.01 to 0.3 mmol per 100 mg of lignocellulose.

[0080] The amount of sulfonic acid or sulfuric acid used as component (C) is, for example, 1 to 100 μmol, preferably 5 to 70 μmol, particularly preferably 10 to 50 μmol, and most preferably 15 to 40 μmol per 100 mg of lignocellulose.

[0081] The amount of the compound represented by formula (c-1) above (preferably a compound represented by formula (c-1-1) or (c-1-2) above, particularly preferably a compound represented by formula (c-1-3) or (c-1-4) above) used as component (C) is, for example, 1 to 100 μmol, preferably 5 to 70 μmol, particularly preferably 10 to 50 μmol, and most preferably 15 to 40 μmol per 100 mg of lignocellulose.

[0082] When component (C) is used in the above range, it is possible to suitably promote the progress of the delignification reaction together with components (B) and (E).

[0083] (Component (D)) Component (D) is a component used in the method for producing a cellulose-containing composition according to the second aspect of the present disclosure, and is an acid different from peroxides and the peracids. It is also preferable to use the specific acid as component (C) as component (D).

[0084] Examples of the component (D) include inorganic acids and organic acids, which may be used alone or in combination of two or more.

[0085] Examples of inorganic acids include sulfuric acid, nitric acid, and phosphoric acid.

[0086] Examples of organic acids include carboxylic acids, sulfonic acids, phosphonic acids, and phosphinic acids. The organic acids may be hydrates. When the organic acids have a plurality of acid groups, some of the acid groups may form salts. An organic acid in which some of the acid groups form salts may be liquid at room temperature (25°C). That is, the organic acids may be ionic liquids.

[0087] Examples of the salts that may be formed by the organic acids include alkali metal salts such as sodium salts and potassium salts; alkaline earth metal salts such as calcium salts and magnesium salts; and amine salts such as imidazole salts and pyridine salts.

[0088] The carboxylic acid is a compound having at least one carboxyl group, and examples thereof include monocarboxylic acids such as formic acid, acetic acid, succinic acid, lactic acid, glycolic acid, and glyoxylic acid; and polycarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutamic acid, maleic acid, humic acid, phthalic acids, citric acid, and malic acid.

[0089] Preferred examples of the carboxylic acid include maleic acid and its derivatives, and aliphatic monocarboxylic acids such as glyoxylic acid.

[0090] The sulfonic acid is a compound having at least one sulfonic acid group (SO3H group), and is represented, for example, by the following formula (c): R-(SO3H) n (c)

[0091] In the formula (c), R represents an n-valent hydrocarbon group or an n-valent heterocyclic group, and n represents an integer of 1 or more.

[0092] Among the n-valent hydrocarbon groups in R, the monovalent hydrocarbon group is 11 Examples of the n-valent hydrocarbon group, where n is an integer of 2 or greater, include groups in which n-1 hydrogen atoms have been removed from the structural formula of the monovalent hydrocarbon group.

[0093] The heterocycle constituting the n-valent heterocyclic group in R includes aromatic heterocycles and non-aromatic heterocycles. Examples of the heterocycle include 3- to 10-membered rings (preferably 4- to 6-membered rings) containing carbon atoms and at least one heteroatom (e.g., oxygen atom, sulfur atom, nitrogen atom, phosphorus atom, etc.) as ring-constituting atoms. The heterocycle may be condensed with a 3- to 8-membered cycloalkane ring.

[0094] Furthermore, from the viewpoint of more suitably exerting the effects of the present invention, the acid dissociation constant (pKa) of component (D) is, for example, less than −0.25, less than −0.4, −0.6 or less, −2.0 or less, or −2.8 or less, and the lower limit is, for example, −7.9 or more, preferably −7.5 or more, more preferably −7.0 or more, and particularly preferably −6.0 or more. A preferred range is, for example, −7.5 to −0.6.

[0095] The amount of component (D) used (the total amount when two or more types of component (D) are used) can be appropriately changed depending on the type of component (D), but is, for example, 0.001 to 1.0 mmol, preferably 0.005 to 0.5 mmol, and preferably 0.01 to 0.3 mmol per 100 mg of lignocellulose.

[0096] The amount of carboxylic acid used as component (D) is, for example, 0.01 to 1.0 mmol, preferably 0.02 to 0.8 mmol, and particularly preferably 0.03 to 0.6 mmol, per 100 mg of lignocellulose.

[0097] The amount of sulfonic acid or sulfuric acid used as component (D) is, for example, 1 to 100 μmol, preferably 5 to 70 μmol, particularly preferably 10 to 50 μmol, and most preferably 15 to 40 μmol, per 100 mg of lignocellulose.

[0098] When component (D) is a compound corresponding to component (C), the amount of the compound represented by formula (c-1) used as component (D) is, for example, 1 to 100 μmol, preferably 5 to 70 μmol, particularly preferably 10 to 50 μmol, and most preferably 15 to 40 μmol per 100 mg of lignocellulose.

[0099] When component (D) is used within the above range, it is possible to favorably promote the progress of the delignification reaction together with component (B) and component (E), and to obtain a cellulose composition that is easily refined by a refinement treatment to give cellulose nanofibers with a small width.

[0100] (Component (E)) Component (E) is a solvent used in the method for producing a cellulose-containing composition of the present disclosure. In the method for producing a cellulose-containing composition of the present disclosure, the delignification reaction of biomass containing lignocellulose is carried out in a solvent.

[0101] In the method for producing a cellulose-containing composition according to the first aspect of the present disclosure, the solvent as component (E) is not particularly limited as long as it does not impair the effects of the present disclosure.

[0102] On the other hand, in the method for producing a cellulose-containing composition according to the second aspect of the present disclosure, the solvent as component (E) has an octanol / water partition coefficient (logP オクタノール / 水 ) is 0.5 or more, or is at least one solvent selected from the group consisting of hydrocarbon solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, and ester solvents.

[0103] In the method for producing a cellulose-containing composition according to the first aspect of the present disclosure, it is preferable to use at least one of water and an organic solvent as the solvent.

[0104] In the first aspect of the present disclosure, examples of organic solvents include alcohol-based solvents such as methanol, ethanol, propanol, and butanol; ether-based solvents such as diethyl ether, diisopropyl ether, dibutyl ether, tetrahydrofuran, dioxane, dioxolane, 1,2-dimethoxyethane, and cyclopentyl methyl ether; ester-based solvents such as butyl acetate and ethyl acetate; hydrocarbon-based solvents such as pentane, hexane, cyclohexane, heptane, and octane; aromatic hydrocarbon-based solvents such as benzene and toluene; halogenated hydrocarbon-based solvents such as carbon tetrachloride, trichloroethylene, chloroform, 1,1,1-trichloroethane, methylene dichloride, ethylene dichloride, monochlorobenzene, and chloronaphthalene; amide-based solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide, and N-methylpyrrolidone; and nitrile-based solvents such as acetonitrile and benzonitrile. These solvents may be used alone or in combination of two or more.

[0105] In the method for producing a cellulose-containing composition according to the first aspect of the present disclosure, it is also a preferred embodiment to use the specific solvent used in the second aspect of the present disclosure described below as component (E).

[0106] In the method for producing a cellulose-containing composition according to the second aspect of the present disclosure, the solvent as component (E) is a solvent having an octanol / water partition coefficient (logP オクタノール / 水 ) satisfies a ratio of 0.5 or more, or at least one solvent selected from the group consisting of hydrocarbon solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, and ester solvents. In a second aspect of the present disclosure, by using these specific solvents as component (E) together with components (B) and (D), a novel cellulose-containing composition can be obtained that gives extremely fine cellulose nanofibers, for example, with an average fiber width of 100 nm or less, or even 10 nm or less, by micronization treatment using a high-pressure homogenizer or the like, without chemically modifying and / or regenerating biomass containing lignocellulose.

[0107] In the method for producing a cellulose-containing composition according to the second aspect of the present disclosure, the octanol / water partition coefficient (logP オクタノール / 水 ) may be 0.5 or more, but from the viewpoint of more suitably exhibiting the effects of the present invention, it is preferably 1.0 or more, more preferably 2.0 or more, and even more preferably 2.5 or more. It is often 10 or less, and even more often 6 or less.

[0108] Octanol / water partition coefficient of the solvent (log P オクタノール / 水 ) are based on the values ​​listed on the product safety data sheets on the Ministry of Health, Labor and Welfare's "Workplace Safety Site."

[0109] Octanol / water partition coefficient (logP オクタノール / 水 ) is 0.5 or more, examples of the solvent include ethyl acetate, chloroform, cyclohexane, toluene, and xylene.

[0110] In the method for producing a cellulose-containing composition according to the second aspect of the present disclosure, the solvent as component (E) is a hydrocarbon solvent, an aromatic hydrocarbon solvent, a halogenated hydrocarbon solvent, or an ester solvent, and has an octanol / water partition coefficient (logP オクタノール / 水 The solvent used in the method for producing a cellulose-containing composition according to the second aspect of the present disclosure may be one type or two or more types.

[0111] In the method for producing a cellulose-containing composition according to the second aspect of the present disclosure, specific examples of hydrocarbon solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, and ester solvents include the same solvents as those exemplified for the first aspect of the present disclosure.

[0112] In the method for producing a cellulose-containing composition of the present disclosure, the amount of solvent used (the total amount when two or more types are used) can be selected appropriately taking into consideration operability, reaction rate, etc., and is, for example, 0.1 to 5 ml, preferably 0.3 to 2 ml, per 100 mg of lignocellulose.

[0113] (Conditions for Delignification Step) In the method for producing a cellulose-containing composition of the present disclosure, the atmosphere in the step of delignifying lignocellulose (delignification step) is not particularly limited as long as it does not inhibit the delignification reaction, and may be, for example, an air atmosphere, a nitrogen atmosphere, an argon atmosphere, or the like.

[0114] The delignification reaction may be carried out under normal pressure, reduced pressure, or increased pressure. In the method of the present disclosure, since a peroxide and / or a peracid is used, the reaction can proceed efficiently even when carried out under normal pressure (for example, under an atmosphere of 0.5 to 5.0 atm).

[0115] The reaction temperature (temperature conditions) of the delignification reaction is, for example, 120°C or lower, and from the viewpoint of more suitably exerting the effects of the present invention, is preferably 100°C or lower, more preferably 90°C or lower, even more preferably 85°C or lower, and particularly preferably 80°C or lower. The lower limit of the reaction temperature is, for example, 50°C, preferably 55°C, and particularly preferably 60°C. The reaction time is, for example, about 0.5 to 48 hours, preferably 1 to 24 hours, and particularly preferably 2 to 8 hours. The reaction can be carried out by any method, such as a batch method, a semi-batch method, or a continuous method.

[0116] When lignocellulose is subjected to a delignification reaction, the lignin constituting the lignocellulose is oxidized and / or decomposed to form lignin oxides and / or decomposition products. The lignin oxides and / or decomposition products thus formed are separated from the lignocellulose and dissolved in a solvent without condensation. As a result, a cellulose composition is obtained that can be easily refined by a refinement treatment to give narrow cellulose nanofibers.

[0117] The resulting unrefined cellulose-containing composition (suspension) contains lignin oxides and / or decomposition products dissolved in a solvent and the cellulose-containing composition dissolved and / or dispersed in the solvent. The cellulose-containing composition preferably contains lignin oxides and / or decomposition products dissolved in a solvent and polysaccharides such as cellulose and hemicellulose dispersed in the solvent (a portion of the polysaccharides may be dissolved in the solvent, and a portion of the lignin may be dispersed in the solvent).

[0118] If the unpurified cellulose-containing composition (suspension) is cooled to room temperature (e.g., 25°C) as necessary, and then subjected to a separation process such as filtration (for example, filter paper with a pore size of 1 to 5 μm can be used as the filtration membrane) or centrifugation, the cellulose-containing composition is concentrated, and lignin oxides and / or decomposition products are concentrated in the liquid phase.

[0119] That is, the method for producing a cellulose-containing composition of the present disclosure can further include a step of separating the suspension containing the cellulose-containing composition produced in the delignification step into a phase containing cellulose as the main solid content and a phase derived from biomass and solubilized or liquefied in a solvent.

[0120] For example, the filtrate obtained by filtration (a phase derived from biomass that has been solubilized or liquefied in a solvent) is mainly composed of lignin dissolved in the solvent in an oxidized and / or decomposed state. The oxides and / or decomposition products of lignin contained in the filtrate are highly reactive and soluble, and can be suitably used as raw materials for phenolic compounds and muconic acids.

[0121] Furthermore, if the unpurified cellulose-containing composition (suspension) is cooled to room temperature (e.g., 25°C) as necessary and then subjected to a filtration treatment (for example, filter paper or filter cloth with a pore size of 1 to 5 µm can be used as the filtration membrane), a filtrate containing cellulose as the main solid content can be obtained.

[0122] The proportion of cellulose (glucose in constituent sugar analysis) in the total amount of the cellulose-containing composition (phase containing cellulose as the main solid content (solid phase such as filtrate)) after the separation step is, for example, 50% by weight or more, preferably 65% ​​by weight or more, more preferably 70% by weight or more, particularly preferably 75% by weight or more, and most preferably 80% by weight or more. Furthermore, the amount of lignin, lignin oxides and / or decomposition products mixed into the cellulose-containing composition after the separation step is, for example, 15% by weight or less, preferably 5% by weight or less, more preferably 3% by weight or less, particularly preferably 2% by weight or less of the total amount of the cellulose-containing composition (phase containing cellulose as the main solid content (solid phase such as filtrate)). A step of further reducing components such as lignin may be included after or before the separation step.

[0123] Furthermore, when the filtered residue is subjected to a drying treatment, a fibrous or powdery cellulose-containing composition containing cellulose as the main solid content is obtained. The filtered residue may be subjected to a washing treatment before the drying treatment, if necessary. Water or the above-mentioned organic solvents can be used for the washing treatment.

[0124] Furthermore, in the present disclosure, in the delignification step or a subsequent step, a portion of the hydroxyl groups of the cellulose contained in the cellulose-containing composition may be subjected to etherification, esterification, azide, amination, or the like. Etherification of cellulose gives etherified cellulose, esterification of cellulose gives esterified cellulose, azide of cellulose gives azide cellulose, and amination gives aminated cellulose. Esterification, azide, and amination of cellulose are known, and known methods can be used, but it is necessary to retain a portion of the cellulose that retains its crystalline structure.

[0125] It should be noted that etherification, esterification, azide conversion, and amination of cellulose do not constitute chemical modifications for pulverizing cellulose to facilitate the production of cellulose nanofibers. For example, esterification of cellulose has a weak effect on facilitating the production of cellulose nanofibers, but even if cellulose is esterified, it is difficult to pulverize cellulose to, for example, an average fiber width of 10 nm or less. Chemical modifications for pulverizing cellulose to facilitate the production of cellulose nanofibers include conventional methods such as TEMPO oxidation and xanthation, and such chemical modifications are not necessary, and are preferably not performed, in the method for producing a cellulose-containing composition of the present disclosure.

[0126] The solid content of the cellulose-containing composition obtained by the manufacturing method of the present disclosure has, for example, the following composition. The proportion of glucose in the solid content of the cellulose-containing composition is, for example, 50% by weight or more, preferably 60% by weight or more, and particularly preferably 80% by weight or more. The upper limit is, for example, 100% by weight, particularly 97% by weight, and particularly preferably 95% by weight. The proportion of xylose constituting the solid content of the cellulose-containing composition is, for example, 20% by weight or less, preferably 10% by weight or less, and particularly preferably 7% by weight or less. The lower limit is, for example, 0.5% by weight, preferably 1.0% by weight, and particularly preferably 2.0% by weight. The proportion of mannose constituting the solid content of the cellulose-containing composition is, for example, 15% by weight or less, preferably 12% by weight or less, and particularly preferably 10% by weight or less. The lower limit is, for example, 0.5% by weight, preferably 1.0% by weight, and particularly preferably 2.0% by weight.

[0127] The proportion of galactose constituting the solid content of the cellulose-containing composition is, for example, 5% by weight or less, preferably 3% by weight or less, particularly preferably 2% by weight or less, and most preferably 1% by weight or less.

[0128] Furthermore, the proportion of arabinose constituting the solid content of the cellulose-containing composition is, for example, 3% by weight or less, preferably 2% by weight or less, particularly preferably 1% by weight or less, and most preferably 0.5% by weight or less.

[0129] The weight average molecular weight (Mw) of the solid content contained in the cellulose-containing composition is, for example, 10,000 to 1,500,000, preferably 100,000 to 1,400,000, more preferably 100,000 to 1,000,000, particularly preferably 150,000 to 1,200,000, 150,000 to 900,000, etc., and most preferably 200,000 to 1,000,000, 200,000 to 800,000, etc. The molecular weight distribution Mw / Mn is, for example, 2.0 to 40. The weight average molecular weight (Mw) and number average molecular weight (Mn) are pullulan-equivalent values ​​determined by GPC. The weight average molecular weight (Mw) of the solid content contained in the cellulose-containing composition, expressed as a degree of polymerization when the molecular weight of the glucose unit constituting it is 162, is, for example, 62 to 9259, preferably 617 to 6173, particularly preferably 926 to 5556, and most preferably 1235 to 4938.

[0130] The molecular weight (MP) of the solid content contained in the cellulose-containing composition is, for example, 10,000 to 1,500,000, preferably 100,000 to 1,000,000, and particularly preferably 150,000 to 900,000. The molecular weight (MP) is the peak top value of the molecular weight distribution curve determined by GPC. The molecular weight is a pullulan-equivalent value.

[0131] The crystallinity of the cellulose-containing composition obtained by the production method of the present disclosure is, for example, 50% or more, preferably 60% or more. The upper limit of the crystallinity is, for example, 90%.

[0132] The average fiber width of the fibers (cellulose-containing fibers) whose main component is cellulose and which are contained in the cellulose-containing composition obtained by the production method of the present disclosure is preferably 1 μm or more, 2 μm or more, 5 μm or more, etc., and is preferably 100 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less, etc., with preferred ranges being about 1 to 100 μm, about 5 to 20 μm, etc. The average fiber width of the fibers whose main component is cellulose can be determined by taking images of a sufficient number (e.g., 30 or more) of fibrous powders using an electron microscope (SEM, TEM) or other microscope, measuring the fiber widths, and calculating the arithmetic average.

[0133] In addition, fibers (cellulose-containing fibers) containing cellulose as the main component and contained in the cellulose-containing composition of the present invention, for example, those having an average fiber width of 1 μm or more, may be first finely divided to 1 μm or less, and then further finely divided to a fiber width of 100 nm or less, or even 10 nm or less, using a high-pressure homogenizer or the like.

[0134] The average fiber length (L) of the fibers (cellulose-containing fibers) containing cellulose as a main component contained in the cellulose-containing composition obtained by the production method of the present disclosure is, for example, 10 μm or more, preferably 100 μm or more, and more preferably 200 μm or more. The upper limit of the average fiber length is, for example, 3000 μm, preferably 1000 μm.

[0135] The average aspect ratio (average fiber length / average fiber width) of the fibers (cellulose-containing fibers) mainly composed of cellulose contained in the cellulose-containing composition obtained by the production method of the present disclosure is, for example, 3 or more, preferably 5 or more, more preferably 10 or more, and even more preferably 20 or more. The upper limit of the average aspect ratio is, for example, 1000, preferably 500.

[0136] The cellulose-containing composition obtained by the production method of the present disclosure preferably has, in an X-ray diffraction pattern in the 2θ range of 0° to 30°, one or two peaks in the range of 14°≦to 2θ≦18° and in the range of 20°≦2θ≦24°, and preferably has no peaks in other ranges.

[0137] The cellulose-containing composition obtained by the production method of the present disclosure can provide extremely fine cellulose nanofibers, for example, with an average fiber width of 100 nm or less, or even 10 nm or less, by micronization treatment using a high-pressure homogenizer or the like, without chemically modifying and / or regenerating biomass containing lignocellulose. For this reason, the cellulose-containing composition obtained by the production method of the present disclosure is particularly useful as a raw material for cellulose nanofibers.

[0138] Furthermore, the cellulose contained in the cellulose-containing composition obtained by the production method of the present disclosure is useful not only as a raw material for paper and fiber, but also as a raw material for cellulose derivatives (e.g., cellulose ether, cellulose ester, cellulose azide, aminated cellulose, carboxymethyl cellulose, etc.); a raw material for bioplastics; and the like.

[0139] Furthermore, the cellulose-containing composition obtained by the production method of the present disclosure is useful, for example, as a thickener, coating agent, binder, disintegrant, bonding agent, base, excipient, lubricant, emulsifier, surfactant, bitterness masking agent, cosmetic ingredient, etc.

[0140] [Cellulose-Containing Composition] The cellulose-containing composition of the present disclosure is a cellulose-containing composition that, when subjected to high-pressure homogenizer treatment under the following conditions, produces cellulose nanofibers having an average fiber width of 100 nm or less after 10 or fewer treatments. Furthermore, the cellulose-containing composition of the present disclosure may be a cellulose-containing composition that, when subjected to high-pressure homogenizer treatment under the following conditions, produces cellulose nanofibers having a light transmittance of 50% or more (i.e., cellulose nanofibers according to the second aspect described below) after 10 or fewer treatments when made into an aqueous dispersion having a solids concentration of 0.1% by mass, as measured using a spectrophotometer at a wavelength of 660 nm and an optical path length of 1 cm.

[0141] (Conditions for high-pressure homogenizer treatment) The cellulose-containing composition to be subjected to high-pressure homogenizer treatment is an aqueous dispersion with a solids concentration of 0.3 to 1.0% by mass. The treatment pressure is within the range of 150 to 245 MPa, the nozzle diameter is 0.1 to 0.15 mm, the treatment temperature is 25°C ± 25°C, and the number of treatments is 10 or less. Even when the treatment pressure is within the range of 100 to 245 MPa, it is preferable that the cellulose-containing composition produces cellulose nanofibers having an average fiber width of 100 nm or less, or the cellulose nanofibers according to the second aspect described below. In particular, it is preferable that the cellulose-containing composition produces cellulose nanofibers having an average fiber width of 100 nm or less, or even the cellulose nanofibers according to the second aspect described below, even when the treatment pressure is 100 MPa.

[0142] As mentioned above, conventionally, the decomposition and removal of lignin from lignocellulose requires the application of a large amount of energy, and is not easy. Furthermore, even when cellulose from which lignin has been removed by applying a large amount of energy is further refined, the average fiber width of the resulting cellulose nanofibers exceeds, for example, 100 nm unless excessive energy is applied, and it is difficult to obtain cellulose nanofibers refined to an average fiber width of, for example, 10 nm or less. Furthermore, even in methods that do not require the application of a large amount of energy during refinement, when decomposing and removing lignin from lignocellulose, and further when obtaining cellulose nanofibers by refining cellulose, it is necessary to chemically modify (chemically modify) the cellulose using special chemicals, such as TEMPO oxidation of cellulose or xanthation of cellulose.

[0143] In contrast, the cellulose-containing composition of the present disclosure, unlike conventional cellulose-containing compositions, produces cellulose nanofibers with an average fiber width of 100 nm or less, or even 10 nm or less, less than 10 nm, 8 nm or less, 6 nm or less, or 4 nm or less, after 10 or fewer high-pressure homogenizer treatments under the above-mentioned conditions without undergoing chemical modification and / or regeneration treatment. Furthermore, cellulose nanofibers with an average fiber width of 10 nm or less can be produced after 8 or fewer high-pressure homogenizer treatments, 5 or fewer high-pressure homogenizer treatments, 2 or fewer high-pressure homogenizer treatments, or even after one high-pressure homogenizer treatment.

[0144] The method for producing such a cellulose-containing composition of the present disclosure is not particularly limited, but it can be suitably produced by the production method described in the above section [Method for producing a cellulose-containing composition].

[0145] Therefore, the cellulose-containing composition of the present disclosure can be produced by delignifying biomass containing lignocellulose. Specific examples of lignocellulose-containing biomass that can be used as a raw material for the cellulose-containing composition of the present disclosure are as described above in the section "Method for producing a cellulose-containing composition."

[0146] Furthermore, the composition of the solid contents contained in the cellulose-containing composition of the present disclosure (i.e., the proportion of glucose in the solid contents, the proportion of xylose constituting the solid contents, the proportion of mannose constituting the solid contents, the proportion of galactose constituting the solid contents, the proportion of arabinose constituting the solid contents, the total proportion of glucose, xylose, mannose, galactose, and arabinose constituting the solid contents, the weight-average molecular weight (Mw) of the solid contents, the molecular weight (MP) of the solid contents, the crystallinity of cellulose, the average fiber width of cellulose, the average fiber length (L) of cellulose, the average aspect ratio of cellulose (average fiber length / average fiber width), and the X-ray diffraction pattern of cellulose) are the same as those described in the above-mentioned section [Method for producing a cellulose-containing composition], and therefore these descriptions will be omitted.

[0147] The cellulose-containing composition of the present disclosure can provide extremely fine cellulose nanofibers, for example, with an average fiber width of 100 nm or less, or even 10 nm or less, by the above-mentioned high-pressure homogenizer treatment to pulverize lignocellulose-containing biomass without chemically modifying and / or regenerating the biomass. For this reason, the cellulose-containing composition of the present disclosure is particularly useful as a raw material for cellulose nanofibers.

[0148] Furthermore, the cellulose contained in the cellulose-containing composition of the present disclosure is useful not only as a raw material for paper and fiber, but also as a raw material for cellulose derivatives (e.g., cellulose ether, cellulose ester, cellulose azide, aminated cellulose, carboxymethyl cellulose, etc.); a raw material for bioplastics; and the like.

[0149] Furthermore, the cellulose contained in the cellulose-containing composition of the present disclosure is useful, for example, as a thickener, coating agent, binder, disintegrant, bonding agent, base, excipient, lubricant, emulsifier, surfactant, bitterness masking agent, cosmetic ingredient, etc.

[0150] [Method for producing cellulose nanofiber-containing composition] The method for producing a cellulose nanofiber-containing composition of the present disclosure includes a step of subjecting the cellulose-containing composition obtained by the method for producing a cellulose-containing composition of the present disclosure, as described above in the section [Method for producing a cellulose-containing composition], to a micronization treatment until the average fiber width of the fibers (cellulose-containing fibers) composed primarily of cellulose is 100 nm or less, thereby obtaining cellulose nanofibers.

[0151] The method for micronizing fibers (cellulose-containing fibers) primarily composed of cellulose contained in a cellulose-containing composition until the average fiber width is 100 nm or less may be any method capable of defibrating cellulose fiber bundles. The cellulose-containing composition is composed of cellulose fiber bundles having an average fiber width of 1 μm or more, in which multiple cellulose fibers are bonded by hydrogen bonding. These cellulose fiber bundles are micronized to cellulose nanofibers by micronization treatment.

[0152] In the method for producing a cellulose nanofiber-containing composition of the present disclosure, it is preferable to micronize the cellulose by high-pressure homogenizer treatment. As described above, the cellulose-containing composition obtained by the method for producing a cellulose-containing composition of the present disclosure can easily produce extremely fine cellulose nanofibers, for example, with an average fiber width of 100 nm or less, or even 10 nm or less, by micronization treatment using a high-pressure homogenizer with a low number of treatments, without chemically modifying and / or regenerating the lignocellulose-containing biomass. Therefore, high-pressure homogenizer treatment is preferred as the method for micronization treatment. Prior to micronization treatment such as high-pressure homogenizer treatment, the cellulose-containing composition may be lightly micronized using a different micronization device or under different conditions.

[0153] The cellulose-containing composition to be subjected to the pulverization treatment may be dried.

[0154] As the high-pressure homogenizer, a commercially available product can be used. The conditions for the high-pressure homogenizer treatment are not particularly limited, as long as extremely fine cellulose nanofibers having an average fiber width of 100 nm or less, or even 10 nm or less, can be obtained.

[0155] From the viewpoint of more suitably exerting the effects of the present invention, the solids concentration of the cellulose-containing composition subjected to the high-pressure homogenizer treatment is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more. Also, preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less. Preferred ranges include about 0.1 to 3.0% by mass, about 0.1 to 2.0% by mass, about 0.1 to 1.5% by mass, about 0.1 to 1.0% by mass, about 0.2 to 2.0% by mass, about 0.2 to 1.5% by mass, about 0.2 to 1.0% by mass, about 0.3 to 2.0% by mass, about 0.3 to 1.5% by mass, and about 0.3 to 1.0% by mass.

[0156] From the viewpoint of more suitably exerting the effects of the invention of the present disclosure, the treatment pressure of the high-pressure homogenizer treatment is preferably 50 MPa or more, more preferably 100 MPa or more, even more preferably 150 MPa or more, and preferably 300 MPa or less, more preferably 260 MPa or less, even more preferably 245 MPa or less. Preferred ranges include about 100 to 300 MPa, about 100 to 260 MPa, about 100 to 245 MPa, about 100 to 150 MPa, about 120 to 300 MPa, about 120 to 260 MPa, about 120 to 245 MPa, about 150 to 300 MPa, about 150 to 260 MPa, and about 150 to 245 MPa.

[0157] Furthermore, from the viewpoint of more suitably exerting the effects of the invention of the present disclosure, when a nozzle is used in the high-pressure homogenizer treatment, the nozzle diameter is preferably 0.10 mm or more, more preferably 0.15 mm or more, and is preferably 0.60 mm or less, more preferably 0.50 mm or less, and even more preferably 0.30 mm or less. Preferred ranges include about 0.10 to 0.50 mm, about 0.10 to 0.40 mm, about 0.15 to 0.50 mm, about 0.15 to 0.40 mm, about 0.20 to 0.50 mm, about 0.20 to 0.40 mm, about 0.15 to 0.50 mm, about 0.15 to 0.30 mm, and about 0.15 to 0.25 mm.

[0158] The processing temperature in the high-pressure homogenizer treatment is controlled, for example, within the range of 25°C ± 25°C, preferably within the range of 25°C ± 20°C, and more preferably within the range of 25°C ± 15°C.

[0159] Furthermore, from the viewpoint of more suitably exerting the effects of the present invention, the number of times of high-pressure homogenizer treatment is preferably one or more, more preferably two or more, and is preferably 20 or less, more preferably 10 or less, and even more preferably 5 or less.

[0160] Furthermore, among the components of the cellulose nanofibers obtained by the method for producing a cellulose nanofiber-containing composition of the present disclosure, the following described in the section [Method for producing a cellulose-containing composition] above, such as the proportion of glucose in the solid content, the proportion of xylose constituting the solid content, the proportion of mannose constituting the solid content, the proportion of galactose constituting the solid content, the proportion of arabinose constituting the solid content, the total proportion of glucose, xylose, mannose, galactose, and arabinose constituting the solid content, the weight-average molecular weight (Mw) of the solid content, the molecular weight (MP) of the solid content, the crystallinity of cellulose, the average fiber length (L) of cellulose, and the X-ray diffraction pattern of cellulose, are the same for cellulose nanofibers, and therefore descriptions of these will be omitted.

[0161] On the other hand, the average fiber width of the cellulose nanofibers contained in the cellulose nanofiber-containing composition of the present disclosure is, for example, 100 nm or less, preferably 10 nm or less, more preferably less than 10 nm, even more preferably 8 nm or less, even more preferably 6 nm or less, and even more preferably 4 nm or less, and the lower limit is, for example, 1 nm or more, 2 nm or more, or 3 nm or more.

[0162] Furthermore, the average aspect ratio (average fiber length / average fiber width) of the cellulose nanofibers contained in the cellulose nanofiber-containing composition of the present disclosure is, for example, 10 or more, preferably 20 or more, more preferably 30 or more, even more preferably 50 or more, further preferably 100 or more, or even more preferably 200 or more. The upper limit of the average aspect ratio is, for example, 10,000, preferably 5,000.

[0163] The average fiber width of the cellulose nanofibers is a value obtained by measuring 50 or more cellulose nanofibers using atomic force microscopy (AFM) and calculating the average value. The specific measurement method is as described below in <Method for observing the shape of the pulverized product and measuring the width by AFM>.

[0164] The cellulose nanofibers contained in the cellulose nanofiber-containing composition of the present disclosure preferably have not been subjected to chemical modification and / or regeneration treatment. As described above, etherification, esterification, azide, and amination of cellulose do not constitute chemical modifications for pulverizing cellulose to facilitate the production of cellulose nanofibers. Therefore, with regard to chemical modifications of cellulose nanofibers, etherification, esterification, azide, and amination of cellulose are not included in these chemical modifications. Chemical modifications for pulverizing cellulose to facilitate the production of cellulose nanofibers include conventional methods such as TEMPO oxidation and xanthation, and the cellulose nanofibers contained in the cellulose nanofiber-containing composition of the present disclosure do not need to be, and preferably have not been, subjected to such chemical modification and / or regeneration treatment.

[0165] The cellulose nanofibers contained in the cellulose nanofiber-containing composition obtained by the production method of the present disclosure are useful not only as raw materials for paper, film, and fiber, but also as raw materials for cellulose derivatives (e.g., cellulose ether, cellulose ester, cellulose azide, aminated cellulose, carboxymethyl cellulose, etc.); raw materials for bioplastics; and the like.

[0166] Furthermore, the cellulose nanofibers contained in the cellulose nanofiber-containing composition obtained by the production method of the present disclosure are useful as, for example, thickeners, coating agents, paints, binders, disintegrants, bonding agents, bases, excipients, lubricants, emulsifiers, surfactants, bitterness masking agents, cosmetic raw materials, etc. Furthermore, they are useful as gas barrier materials, raw materials for saccharification using enzymes or acids, raw materials for ethanol, raw materials for Sustainable Aviation Fuel (SAF), raw materials for methane, food additives such as dietary fiber, Pickering emulsions, foams or foam additives, superabsorbent materials, raw materials for preparing cellulose solutions, and cell culture materials (3D bioprinting, etc.). The cellulose nanofibers obtained by the production method of the present disclosure are finely divided using less energy, which significantly contributes to reducing greenhouse gas (GHG). Since it can be miniaturized to a width of 100 nm or less, or even 10 nm or less, it is suitable for applications requiring properties such as a large surface area, transparency, thixotropy, and high dispersibility. Furthermore, since it retains cellulose crystals, it is suitable for applications requiring properties such as light weight, high strength, high elasticity, and low linear thermal expansion. Furthermore, since it is not chemically modified, it is suitable for applications utilizing biodegradability and hydroxyl groups.

[0167] [Cellulose Nanofiber] The cellulose nanofiber according to the first aspect of the present disclosure is a cellulose nanofiber that has not been subjected to chemical modification and / or regeneration treatment and has an average fiber width of 10 nm or less.

[0168] Furthermore, the cellulose nanofibers according to the second aspect of the present disclosure are cellulose nanofibers that have not been chemically modified and / or regenerated, and when dispersed in water at a solids concentration of 0.1% by mass, have a light transmittance of, for example, 50% or more, preferably 60% or more, more preferably 70% or more, and even more preferably 80% or more, as measured using a spectrophotometer at a wavelength of 660 nm and an optical path length of 1 cm.

[0169] The cellulose nanofibers according to the first and second aspects of the present disclosure can both be suitably produced by the method for producing a cellulose nanofiber-containing composition according to the present disclosure described above in the section [Method for producing a cellulose nanofiber-containing composition]. That is, the cellulose nanofibers according to the present disclosure are suitably produced by using the [cellulose-containing composition] as a raw material and subjecting it to a micronization treatment.

[0170] As mentioned above, conventionally, when cellulose from which lignin has been removed by applying a large amount of energy is further refined, unless a large amount of energy is applied, the average fiber width of the resulting cellulose nanofibers exceeds 100 nm, and it is difficult to obtain cellulose nanofibers that have been refined to an average fiber width of 10 nm or less. Furthermore, even in methods that do not require the application of a large amount of energy, when decomposing and removing lignin from lignocellulose, and further when refining cellulose to obtain cellulose nanofibers, it is necessary to chemically modify (chemically modify) the cellulose using special chemicals such as TEMPO oxidation of cellulose or xanthation.

[0171] In contrast, the cellulose nanofibers according to the first aspect of the present disclosure are novel cellulose nanofibers that have not been chemically modified and / or regenerated and have an average fiber width of 10 nm or less. Furthermore, the cellulose nanofibers according to the second aspect of the present disclosure are not chemically modified and / or regenerated and, when dispersed in water at a solids concentration of 0.1% by mass, exhibit extremely high light transmittance of 50% or more, as measured using a spectrophotometer at a wavelength of 660 nm and an optical path length of 1 cm. This indicates that the average fiber width is extremely small, for example, down to approximately 10 nm or less. The light transmittance was measured by the method described in the Examples.

[0172] Of the configurations of the cellulose nanofibers of the present disclosure, the proportion of glucose in the solid content, the proportion of xylose constituting the solid content, the proportion of mannose constituting the solid content, the proportion of galactose constituting the solid content, the proportion of arabinose constituting the solid content, the weight-average molecular weight (Mw) of the solid content, the molecular weight (MP) of the solid content, the crystallinity of cellulose, the average fiber length (L) of cellulose, and the X-ray diffraction pattern of cellulose, described in the section [Method for producing a cellulose-containing composition] above, are the same for cellulose nanofibers, and so descriptions of these will be omitted.

[0173] Meanwhile, the average fiber width and average aspect ratio (average fiber length / average fiber width) of the cellulose nanofibers of the present disclosure are as described above in the section "Method for producing a cellulose nanofiber-containing composition."

[0174] It is also preferable that the cellulose nanofibers according to the second aspect of the present disclosure have not been subjected to chemical modification and / or regeneration treatment.

[0175] As described above, the cellulose nanofibers of the present disclosure are useful not only as a raw material for paper and fiber, but also as a raw material for cellulose derivatives (e.g., cellulose ester, cellulose ester, cellulose azide, aminated cellulose, carboxymethyl cellulose, etc.); a raw material for bioplastics; and the like.

[0176] As described above, the cellulose nanofibers contained in the cellulose nanofiber-containing composition obtained by the production method of the present disclosure are useful as, for example, thickeners, coating agents, binders, disintegrants, bonding agents, bases, excipients, lubricants, emulsifiers, surfactants, bitterness masking agents, cosmetic raw materials, etc. Furthermore, they are useful as gas barrier materials, raw materials for saccharification using enzymes or acids, raw materials for ethanol, raw materials for Sustainable Aviation Fuel (SAF), raw materials for methane, food additives such as dietary fiber, Pickering emulsions, foams or foam additives, superabsorbent materials, raw materials for preparing cellulose solutions, and cell culture materials (3D bioprinting, etc.). The cellulose nanofibers obtained by the production method of the present disclosure are finely divided using less energy, which significantly contributes to reducing greenhouse gas (GHG). Since it can be miniaturized to a width of 100 nm or less, or even 10 nm or less, it is suitable for applications requiring properties such as a large surface area, transparency, thixotropy, and high dispersibility. Furthermore, since it retains cellulose crystals, it is suitable for applications requiring properties such as light weight, high strength, high elasticity, and low linear thermal expansion. Furthermore, since it is not chemically modified, it is suitable for applications utilizing biodegradability and hydroxyl groups.

[0177] The present disclosure will be explained in more detail below using examples, but the present disclosure is not limited to these examples.

[0178] [Example 1] (Production of Cellulose-Containing Composition A) 100 g of air-dried cedar heartwood flour (average particle size 550 μm, moisture content 12 wt %) was placed in a separable flask. トルエン / 水 = -2.28, pKa = -2.8 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in 200 mL of 30% hydrogen peroxide solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and オクタノール / 水 = 2.73 400 mL of Fujifilm Wako Pure Chemical Industries, Ltd. was added and mixed. Next, the temperature was raised to 60°C while stirring with a stirring blade, and the cedar heartwood flour was reacted for 24 hours to obtain a reaction solution.

[0179] 1000 mL of water was added to the resulting reaction solution, and the contents were stirred and mixed. This caused the toluene to separate from the aqueous phase (layer), and the separated toluene was removed by suction with a syringe. The slurry containing the remaining solids (cellulose-based composition) was stirred for 2 hours, and the dissolved components remaining in the solids were extracted into water. Then, it was filtered using a filter cloth with a pore size of 5 μm. The solids were washed with water, neutralized with an aqueous sodium bicarbonate solution, further washed with water, and filtered to recover cellulose-containing composition A. The water content of the cellulose-containing composition A after draining was 76% (solids 24%).

[0180] (Production of micronized cellulose-containing composition A (cellulose nanofiber-containing composition)) Water was added to the obtained cellulose-containing composition A to prepare a slurry with a solids concentration of 1 wt %. This was stirred for 1 minute at 45 using a Hiscotron NS-50 manufactured by Microtec Nichion Co., Ltd. to disperse the cellulose-containing composition A. At this stage, as shown in Figure 1, most of the fibers had a width of 1 µm or more and had not been micronized, and when left to stand, the fibers easily settled as shown in Figure 2.

[0181] Next, the mixture was subjected to a micronization treatment using a high-pressure homogenizer "Starburst Mini" manufactured by Sugino Machine Co., Ltd., with a treatment temperature maintained at 25°C ± 25°C, a treatment pressure of 245 MPa, a nozzle diameter of 0.1 mm, and two treatment passes. An AFM image of the obtained micronized product is shown in Figure 3. The width of the micronized product (50 or more cellulose nanofibers) was measured using AFM, and the average was 3.45 nm with a standard deviation of 1.03 nm.

[0182] [Example 2] A micronized product was obtained in the same manner as in Example 1, except that the cellulose-containing composition A was treated with the high-pressure homogenizer 10 times. An AFM image of the obtained micronized product is shown in Figure 4. The width of the micronized product (50 or more cellulose nanofibers) was measured using AFM, and the average was 3.68 nm with a standard deviation of 1.04 nm.

[0183] [Examples 3-5] A micronized product was obtained in the same manner as in Example 1, except that the treatment conditions for cellulose-containing composition A in the high-pressure homogenizer were changed to those shown in Table 1. The average fiber width of the obtained micronized product (50 or more cellulose nanofibers) was measured using an AFM or a spectrophotometer, and the results are shown in Table 1.

[0184] Reference 1, "Results of the NEDO-Commissioned Project for the Effective Use of Woody Biomass (2017-2019) - Raw Material Assessment Report for Cellulose Nanofiber Utilization, March 2020," on page 44, states that the width of cellulose nanofibers (CNF) obtained by treating a total of 36 types of pulp (kraft pulp, soda-anthraquinone-cooked pulp, overcooked kraft pulp, prehydrolyzed kraft pulp, and posthydrolyzed kraft pulp) 10 times at 200 MPa with a high-pressure homogenizer (water jet oblique impingement method or ball impingement method) was approximately 10-50 nm. Furthermore, on page 73, it is stated that the fiber width measured using a spectrophotometer was 20-30 nm for the ball impingement method and 20-40 nm for the oblique impingement method. On the other hand, it is stated that the width of CNF chemically modified using the TEM method was 2-4 nm.

[0185] In contrast, the methods for producing cellulose-containing compositions in the examples show that novel cellulose-containing compositions can be produced that can provide extremely fine cellulose nanofibers with an average fiber width of 10 nm or less by pulverization using a high-pressure homogenizer, even without chemically modifying and / or regenerating biomass containing lignocellulose. In fact, in the production of the pulverized products (cellulose nanofiber-containing compositions) in Examples 1 to 5, cellulose-containing composition A obtained by the cellulose-containing composition production method was pulverized using a high-pressure homogenizer, yielding extremely fine cellulose nanofibers with an average fiber width of 10 nm or less.

[0186] The cellulose-containing composition A was dried, and the ATR-IR measurement and the solid 13The results of C-NMR measurements are shown in Figures 5 and 6. For comparison, a chart for cellulose powder (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) is also shown. Cellulose-containing composition A did not show any distinctive peaks compared to cellulose powder, indicating that it was not substantially chemically modified. Analysis of neutral sugar components revealed a glucose content of 79.4%, other neutral sugars of 6.0%, and a Klason lignin content of 2.1%.

[0187] 7 and 8 show examples of the characteristics of the pulverized material obtained from the cellulose-containing composition A.

[0188] Figure 7a) is a photograph of an aqueous dispersion of micronized material prepared under the same conditions as in Examples 1 and 2, but with only the number of passes through the high-pressure homogenizer changed. Figure 7b) shows the result of adding water to cellulose-containing composition A to adjust the solids concentration to 0.7%, and then treating the dispersion with the high-pressure homogenizer for a predetermined number of passes at 150 MPa. In both cases, after just a few passes, the dispersion no longer flows even when the sample bottle is inverted. Furthermore, the transparency of the dispersion increases as the number of passes increases. These changes are thought to be due to the significant progress of micronization even with a small number of passes through the high-pressure homogenizer treatment.

[0189] 8 shows the X-ray diffraction pattern and the results of evaluation of crystallinity of the dried pulverized product obtained in Example 2. The cellulose-containing composition A before pulverization (i.e., before treatment with a high-pressure homogenizer) exhibits the so-called cellulose type I crystalline structure, which is maintained even after treatment with a high-pressure homogenizer (245 MPa, 10 passes), indicating the possibility of utilizing the characteristics of cellulose crystals, such as high elasticity and high strength.

[0190]

[0191] Example 6 Water was added to the cellulose-containing composition A produced in Example 1 to prepare a slurry with a solids concentration of 1 wt %. This was stirred for 1 minute at 45 using a Hiscotron NS-50 manufactured by Microtec Nition Co., Ltd. to disperse the cellulose-containing composition A. Next, using a high-pressure homogenizer "Starburst Mini," the mixture was treated at 200 MPa for the number of passes shown in Figure 10 (i.e., 1, 2, 5, or 10 passes). The resulting micronized product was observed under a fluorescent microscope, and the transmittance of the aqueous dispersion was measured.

[0192] Comparative Example 1: Commercially available bleached kraft pulp (1) (glucose content: 82.4%, other neutral sugar content: 13.2%, Klason lignin content: 1.1%; hereinafter, also referred to as "commercial pulp (1)") was added with water to a solids concentration of 1% by weight, and the pulp was soaked at room temperature for 3 days. This was in accordance with the description on page 79 of the aforementioned Reference 1, which states, "Commercially available pulp is produced by a wet method, but repeated drying and moisture absorption during the drying and distribution processes cause the formation of hydrogen bonds between fibers, which can lead to aggregation. In order to restore the pulp fibers aggregated by hydrogen bonds, etc., it is necessary to soak the pulp in water for a certain period of time, and the pulp was evaluated after soaking in water for 24 hours or more."

[0193] Regarding chemicals used in the kraft pulp manufacturing process, the log P of sodium hydroxide トルエン / 水 = -14.9 (not expressed in pKa because it is a base), log P of sodium sulfide トルエン / 水 = -14.1 (not expressed in pKa because it is a base), log P of water, the solvent オクタノール / 水 = -3.15, log P of hydrogen peroxide オクタノール / 水 = -1.36.

[0194] The water-soaked bleached kraft pulp (1) was first dispersed for 1 minute at 45 using a Hiscotron NS-50, as in Example 1. However, since this pulp was less dispersible than the cellulose-containing composition of Example 1, clumps clearly larger than the nozzle diameter of the high-pressure homogenizer treatment remained, making high-pressure homogenizer treatment impossible. Therefore, the rotation speed of the Hiscotron NS-50 was further increased to 60, and the pulp was dispersed for 5 minutes. Next, the pulp was treated using a high-pressure homogenizer "Starburst Mini" at 200 MPa for the number of passes shown in Figure 10 (i.e., 2, 5, or 10 passes) to obtain a micronized product. The obtained micronized product was observed under a fluorescent microscope, and the transmittance of the aqueous dispersion was measured.

[0195] Comparative Example 2: A commercially available bleached sulfite pulp (2) (glucose content: 91.5%, other neutral sugar content: 6.6%, Klason lignin content: 0%; hereinafter, also referred to as "commercial pulp (2)") was used. The pulp was then pulped in the same manner as in Comparative Example 1. Specifically, water was added to the pulp to a solids content of 1% by weight, and the pulp was immersed in water for 3 days. First, the pulp was dispersed by stirring at 45°C for 1 minute using a Hiscotron NS-50 as in Example 1. However, clumps clearly larger than the nozzle diameter for the high-pressure homogenizer treatment remained, making high-pressure homogenizer treatment impossible. Therefore, the rotation speed of the Hiscotron NS-50 was further increased to 60°C, and the pulp was dispersed for 5 minutes. The pulp was then processed using a high-pressure homogenizer "Starburst Mini" at 200 MPa for the number of passes shown in FIG. 10 (i.e., 10 passes) to obtain a pulverized product. The resulting pulverized product was observed under a fluorescent microscope, and the transmittance of the aqueous dispersion was measured.

[0196] Regarding chemicals used in the sulfite pulp manufacturing process, the log P of sulfite トルエン / 水 = -2.88, pKa = 1.9, log P of calcium sulfite トルエン / 水 = -50.4, pKa = (> -0.25), log P of the solvent water オクタノール / 水 =-3.15, hydrogen peroxide: log P オクタノール / 水 = -1.36.

[0197] FIG. 9 shows fluorescent microscope images of the micronized products obtained in Example 6, Comparative Example 1, and Comparative Example 2.

[0198] In Comparative Example 1 (commercially available bleached kraft pulp (1)) and Comparative Example 2 (commercially available bleached sulfite pulp (2)), the number of thick fibers observable under a fluorescent microscope after 10 passes at 200 MPa was greater than that of Example 6 (cellulose-containing composition A) treated with one pass at 200 MPa. Generally, when substances with a diameter (height) greater than 1 μm are present, observation with an AFM is difficult. Furthermore, when substances with a large diameter that are prone to settling or aggregation are present, it is difficult to measure the fiber diameter using a spectrophotometer. On the other hand, since the transparency of the dispersion (slurry) in which the micronized material is dispersed increases as the micronization progresses, the transmittance of the dispersion was measured using a spectrophotometer to compare the progress and degree of micronization.

[0199] 10 shows the results of measuring the transmittance of 0.1 wt % dispersions prepared by adding water to the pulverized materials obtained in Example 6, Comparative Example 1, and Comparative Example 2. Compared with commercially available pulps (1) and (2), the transmittance of cellulose-containing composition A increases with fewer passes, and achieves a transmittance equivalent to that of commercially available pulps (1) and (2) after 10 passes in one pass.

[0200] Example 7 (Production of Cellulose-Containing Composition B and Micronized Product of Cellulose-Containing Composition B (Cellulose Nanofiber-Containing Composition)) Cellulose-containing composition A was dried at 105°C until it reached a constant weight (considered to have a moisture content of 0% (bone dry)), to obtain cellulose-containing composition B. As in Comparative Examples 1 and 2, cellulose-containing composition B was dispersed using a Hiscotron NS-50 at 45 for 1 minute and at 60 for 5 minutes. Next, using a Starburst Mini manufactured by Sugino Machine Corporation, the mixture was treated at 200 MPa for the number of passes shown in Figure 10 (i.e., 1, 2, 5, or 10 times) to obtain a micronized product.

[0201] Water was added to the resulting pulverized material to prepare a 0.1 wt% dispersion, and the transmittance was measured. The results are shown in Figure 10. It was found that cellulose-containing composition B also provides high transmittance with fewer passes than commercially available pulp. Figure 11 shows AFM images of pulverized material obtained by treating cellulose-containing composition B with two or ten passes. The average fiber width of the pulverized material (50 or more cellulose nanofibers) measured from the AFM images was 3.19 nm (standard deviation 0.93 nm) after two passes and 3.86 nm (standard deviation 1.43 nm) after 10 passes. The cellulose-containing composition of the present invention could be pulverized to a width of 10 nm or less (particularly down to the 3 nm level) even after being completely dried.

[0202] Example 8 (Production of Cellulose-Containing Composition C) 10 g of crushed cedar heartwood flour (moisture content: 12%) having a 1000 μm pass was placed in an eggplant flask. p-toluenesulfonic acid monohydrate (logP トルエン / 水 = -2.28, pKa = -2.8 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in 10 mL of 30% hydrogen peroxide solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and オクタノール / 水 =-0.17 50 mL of FUJIFILM (manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred. The mixture was then heated to 60°C and reacted for 24 hours with stirring. The reaction mixture was removed from the eggplant flask and filtered using filter paper with a 5 μm pore size. The filtered residue was washed with acetic acid, then placed in the eggplant flask, and 8.8 g of acetic anhydride was added. The reaction mixture was then reacted at 60°C for 2 hours. The reaction mixture was then removed from the eggplant flask and filtered using filter paper with a 5 μm pore size. The filtered residue on the filter paper was washed with acetic acid and water, neutralized with aqueous sodium bicarbonate solution, and then washed with water (referred to as cellulose-containing composition C). The glucose content of cellulose-containing composition C was 62.1%, other neutral sugars 8.4%, and Klason lignin content 2.7%. The degree of acetyl group substitution of cellulose-containing composition C was 1.1. Note that the glucose content of cellulose-containing composition C is low due to the presence of acetyl groups.

[0203] (Production of Micronized Cellulose-Containing Composition C (Cellulose Nanofiber-Containing Composition)) Water was added to cellulose-containing composition C to prepare a slurry with a solids concentration of 0.3 wt %. This was micronized using a high-pressure homogenizer "Starburst Mini" under the following conditions: a treatment temperature of 25°C ± 25°C, a treatment pressure of 245 MPa, a nozzle diameter of 0.1 mm, and 10 passes. An AFM image of the obtained micronized product is shown in Figure 12. The average fiber width of the micronized product (50 or more acetylated cellulose nanofibers) measured from the AFM image was 2.38 nm on average (standard deviation 0.75 nm).

[0204] Example 9 (Production of Cellulose-Containing Composition D) 10 g of crushed cedar heartwood flour (moisture content: 12%) having a 1000 μm pass was placed in an eggplant flask. p-toluenesulfonic acid monohydrate (logP トルエン / 水 = -2.28, pKa = -2.8 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in 10 mL of 30% hydrogen peroxide solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and オクタノール / 水 =-0.17 50 mL of FUJIFILM (manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred and mixed. The temperature was then raised to 60°C and the reaction was allowed to proceed for 24 hours with stirring. The reaction mixture was removed from the recovery flask and filtered using filter paper with a pore size of 5 μm. The residue was washed with acetic acid, then placed in a recovery flask, and 38 g of toluene and then 14.2 g of acetic anhydride were added. The reaction mixture was allowed to proceed for 2 hours at 60°C. The reaction mixture was then removed from the recovery flask and filtered using filter paper with a pore size of 5 μm. The residue on the filter paper was washed with acetic acid and water, neutralized with aqueous sodium bicarbonate solution, and then washed with water (referred to as cellulose-containing composition D). The degree of acetyl group substitution of cellulose-containing composition D was 1.2.

[0205] (Production of Micronized Cellulose-Containing Composition D (Cellulose Nanofiber-Containing Composition)) Water was added to Cellulose-Containing Composition D to prepare a slurry with a solids concentration of 0.3 wt%. This was micronized using a high-pressure homogenizer "Starburst Mini" manufactured by Sugino Machine Corporation, maintaining a processing temperature of 25°C ± 25°C, a processing pressure of 245 MPa, a nozzle diameter of 0.1 mm, and 10 processing passes. An AFM image of the obtained micronized product is shown in Figure 13. The average fiber width of the micronized product (50 or more cellulose nanofibers) measured from the AFM image was 3.11 nm on average (standard deviation 1.76 nm).

[0206] Example 10 Water was added to the cellulose-containing composition A produced in Example 1 to prepare a slurry with a solids concentration of 1 wt%. This was stirred for 1 minute at 45 using a Hiscotron NS-50 manufactured by Microtec Nichion Co., Ltd., to disperse the cellulose-containing composition A. Next, using a high-pressure homogenizer "Starburst Mini," the mixture was treated at 100 MPa with a nozzle diameter of 0.15 mm for the number of passes shown in FIG. 18 (i.e., 3 or 10 passes). The transmittance of the resulting aqueous dispersion of the pulp was measured, and the results are shown in FIG. 18 and compared with those of Example 6, Comparative Example 1, and Comparative Example 2. It can be seen that the cellulose-containing composition A achieved a higher transmittance, i.e., was more finely divided, even at a low pressure of 100 MPa and a low number of passes (3 passes), than commercially available pulps (1) and (2) treated at 200 MPa for 10 passes.

[0207] [Example 11] (Production of Cellulose-Containing Composition E) 50 g of air-dried cedar heartwood flour (average particle size 550 μm, moisture content 12 wt %) was placed in a separable flask. トルエン / 水= 4.02, pKa = -2.78, manufactured by Tokyo Chemical Industry Co., Ltd.), 192.5 mL of 30% hydrogen peroxide solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 107.5 mL of deionized water were mixed and dissolved and added. Next, the temperature was raised to 60 ° C while stirring with a stirring blade, and the cedar heartwood wood flour was reacted for 24 hours to obtain a reaction solution. After the resulting reaction solution was cooled to near room temperature, 300 mL of water was added, and the slurry containing the solids (cellulose-based composition) was stirred for 2 hours to disperse the solids. Then, it was filtered using filter paper with a pore size of 5 μm. The solids were washed with water, neutralized with aqueous sodium bicarbonate, further washed with water, and filtered to recover cellulose-containing composition E. The moisture content of cellulose-containing composition E after draining was 81% (solids 19%). Cellulose-containing composition E was dried and analyzed for neutral sugar content, revealing a glucose content of 74.9%, other neutral sugar content of 11.0%, Klason lignin content of 4.0%, and a weight-average molecular weight of 298,000 (degree of polymerization 1,840).

[0208] (Production of Micronized Cellulose-Containing Composition E (Cellulose Nanofiber-Containing Composition)) Water was added to the obtained cellulose-containing composition E to prepare a slurry with a solids concentration of 1 wt %. This was stirred for 1 minute using a Hiscotron NS-50 manufactured by Microtec Nichion Co., Ltd. at 45 degrees to disperse the cellulose-containing composition E. Next, using a high-pressure homogenizer "Starburst Mini," the mixture was treated at 200 MPa and a nozzle diameter of 0.15 mm for the number of passes shown in FIG. 19 (i.e., 2, 5, or 10 passes). Water was added to the obtained aqueous dispersion of the micronized product to form a 0.1 wt % dispersion, and the transmittance was measured. The results are shown in FIG. 19 and compared with those of Example 6, Comparative Example 1, and Comparative Example 2. Even when water was used as solvent E in the first aspect of the present disclosure, the cellulose-containing composition E can achieve a higher transmittance with fewer passes than commercially available pulps (1) and (2). In other words, it can be further micronized with less energy. The weight-average molecular weight of the cellulose-containing composition E (cellulose nanofiber-containing composition) obtained by subjecting the cellulose-containing composition E to 10 passes using the high-pressure homogenizer "Starburst Mini" was 272,000 (degree of polymerization: 1,679), and the decrease from the molecular weight before pulverization (298,000) was small.

[0209] Example 12 (Production of Cellulose-Containing Composition F) 10 g of air-dried cedar heartwood flour (average particle size 690 μm, moisture content 9.5 wt %) was placed in a separable flask. トルエン / 水 = 4.02, pKa = -2.78, manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in 10 mL of 30% hydrogen peroxide solution (manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.), and toluene (logP オクタノール / 水 = 2.73 50 mL of Fujifilm Wako Pure Chemical Industries, Ltd. was added and mixed. Next, the temperature was raised to 60°C while stirring with a stirring blade, and the cedar heartwood flour was reacted for 24 hours to obtain a reaction solution.

[0210] 100 mL of water was added to the resulting reaction solution, and the contents were stirred and mixed. This caused the toluene to separate from the aqueous phase (layer), and the separated toluene was removed by suction with a syringe. The slurry containing the remaining solids (cellulose-based composition) was stirred for 2 hours, and the dissolved components remaining in the solids were extracted into water. It was then filtered using a filter cloth with a pore size of 5 μm. The solids were washed with water, neutralized with aqueous sodium bicarbonate, further washed with water, and filtered to recover cellulose-containing composition F. Cellulose-containing composition F was dried and subjected to neutral sugar analysis, which revealed a glucose content of 65.6%, other neutral sugars of 12.8%, a Klason lignin content of 3.3%, and a weight-average molecular weight of 933,000 (degree of polymerization 5,759).

[0211] (Production of Micronized Cellulose-Containing Composition F (Cellulose Nanofiber-Containing Composition)) Water was added to the obtained cellulose-containing composition F to prepare a slurry with a solids concentration of 1 wt%. This was stirred for 1 minute at 45 using a Hiscotron NS-50 manufactured by Microtec Nichion Co., Ltd. to disperse the cellulose-containing composition F. Next, using a high-pressure homogenizer "Starburst Mini" manufactured by Sugino Machine Co., Ltd., the mixture was micronized under the conditions of a treatment temperature of 25°C ± 25°C, a treatment pressure of 200 MPa, a nozzle diameter of 0.15 mm, and 10 passes. Water was added to the obtained aqueous dispersion of the micronized product to form a 0.1 wt% dispersion, and the transmittance was measured. The result was 85.3%. As shown in Examples 3 and 6 (cellulose composition A), micronized products with a transmittance of more than 80% had a fiber width of 10 nm or less. Therefore, it is believed that the micronized product of the cellulose composition F also had a fiber width of 10 nm or less. In other words, this shows that not only cellulose composition E in Example 11, which has a weight-average molecular weight of 298,000, but also cellulose composition F, which has a weight-average molecular weight of 933,000, can be easily micronized to give a highly transparent dispersion and cellulose nanofibers with a narrow fiber width.

[0212] <Method for observing the shape of the micronized particles and measuring their width using an AFM> Water was added to the aqueous dispersion of the micronized particles to prepare a slurry with a solids concentration of 0.005% by weight. This was dropped onto a cleaved mica substrate and allowed to dry naturally. Images were acquired in tapping mode using a Shimadzu scanning probe microscope S "PM-Nanoa." The height difference between the mica substrate and the micronized particles was measured from the acquired images using measurement software dedicated to the SPM-Nanoa.

[0213] <Method for measuring transmittance and width of micronized material dispersion using a spectrophotometer> Water was added to the micronized material aqueous dispersion to prepare a slurry with a solids concentration of 0.1% by weight. The transmittance at a wavelength of 660 nm was measured using a Shimadzu UV-2600 ultraviolet-visible spectrophotometer in a quartz cell with an optical path length of 1 cm. Water was added to the micronized material aqueous dispersion to prepare a slurry with a solids concentration of 0.03% by weight. The transmittance at a wavelength of 200-800 nm was measured using a Shimadzu UV-2600 in a quartz cell with an optical path length of 1 cm. The width of the micronized product was calculated using the method described in the literature: Michiko Shimizu, Tsuguyuki Saito, Yoshiharu Nishiyama, Shinichiro Iwamoto, Hiroyuki Yano, Akira Isogai, Takashi Endo. Macromolecular Rapid Communications. 2016, 37, 1581-1586.

[0214] <Method for measuring neutral sugar content and lignin content> 1. 0.3 mL of 72 wt% sulfuric acid was added to 20 mg of dried biomass composition and stirred at 30°C for 1 hour. 2. 8.4 mL of water was added, and the mixture was heated and decomposed at 120°C for 1 hour using an autoclave. 3. The reaction product after the thermal decomposition was centrifuged (3500 rpm x 10 minutes) to separate the supernatant and precipitate. The precipitate, which was regarded as lignin, was washed with water until neutral, and then freeze-dried for 12 hours or more to completely dry it, after which its weight was measured. 4. Barium carbonate was added to the supernatant obtained by the centrifugation to neutralize it (the pH of the supernatant was adjusted to 6-8). The neutralized supernatant was then filtered through a 0.22 μm syringe filter (trade name "FILTSTAR Syringe Filter", manufactured by Hawach Scientific) and analyzed by HPLC. The neutral sugar concentrations were calculated using pre-prepared calibration curves. Calibration curves were prepared for glucose, mannose, xylose, galactose, and arabinose, and the concentrations in the measurement solution were quantified. The amounts of these monosaccharides were converted into the amounts of polysaccharides.

[0215] Measurement by HPLC was carried out under the following conditions: Apparatus: LC-4000 HPLC (manufactured by JASCO Corporation) Column: Aminex HPX-87P (300 x 7.8 mm) (manufactured by Bio-Rad Laboratories) Guard column: Micro-Guard Carbo-P Refill Cartridges (30 x 4.6 mm) (manufactured by Bio-Rad Laboratories) Column temperature: 85°C Mobile phase: water Mobile phase flow rate: 0.6 mL / min Detector: ELSD detector

[0216] <ATR-IR Measurement> ATR-IR measurement was carried out using FT / IR-4700 manufactured by JASCO Corporation.

[0217] <Solid 13 C-NMR measurement> Solid 13 C-NMR (CP / MAS) measurement was carried out.

[0218] <Fluorescence Microscopy> 10 μL of a 0.05 wt% cellulose suspension was dropped onto a glass slide, and one drop of Calcofluor White Stain (Sigma-Aldrich Product Information, 18909) and one drop of 10% potassium hydroxide aqueous solution were added. A cover glass was placed on top, and nail polish was applied around the cover glass. Images were taken using a fluorescence microscope (KEYENCE BZ-X810) with a DAPI fluorescence filter (excitation wavelength 360 / 40 nm, absorption wavelength 460 / 50 nm).

[0219] <Method for measuring the degree of acetyl group substitution> ATR-IR measurement was carried out on a dried sample using an FT / IR-4700 manufactured by JASCO Corporation. ATR-IR measurement was also carried out on cellulose acetates having various degrees of acetyl group substitution, and after baseline correction, the acetyl group substitution degree was measured at 1735 cm -1 The absorbance of the peak derived from the acetyl group near 1032 cm -1 The ratio of absorbance of the peaks around 1735 cm -1 / 1032cm -1 ) was calculated and plotted against the degree of substitution, a good correlation was obtained. -1 / 1032cm -1 Using the relational expression between the degree of acetyl group substitution and the Abs value of the sample obtained in the example, -1 / 1032cm -1 was measured and the degree of acetyl group substitution was calculated.

[0220] <X-ray diffraction measurement> A small amount of the sample obtained by freeze-drying was subjected to X-ray diffraction measurement using a tabletop X-ray diffractometer Aeris manufactured by Malvern Panalytical Co., Ltd. From the obtained X-ray diffraction pattern, the amount of cellulose crystals was estimated by the area method as follows.

[0221] Peaks at 2θ: 14.5° (110 plane), 16.5° (110 plane), 20.7° (102 plane), 22.5° (200 plane), and 34.9° (004 plane) were set as diffraction peaks derived from cellulose crystals, and 18.5° was set as a peak in the amorphous region. Peaks were separated using the software of the X-ray diffractometer, and the amount of cellulose crystals was estimated according to the following formula: Amount of cellulose crystals = [total area of ​​diffraction peaks derived from cellulose crystals / total area] × 100 (%)

[0222] <Molecular Weight Measurement> The molecular weight can be determined by gel permeation chromatography (GPC). Specifically, 5 mg of a sample is dissolved in approximately 100 mg of 1-ethyl-3-methylimidazolium chloride. 5 g of DMSO is then added and dissolved, and the solution is filtered through a PTFE cartridge filter, followed by GPC measurement under the following conditions: Apparatus: Nexera (Shimadzu Corporation) Column: One PLGEL 20 μm MIXED-A 300 mm - 7.5 mm Guard column: One PLgel 20 μm Guard 50 × 7.5 mm Detector: RI detector, polarity (+) Eluent: 1% 1-ethyl-3-methylimidazolium chloride solution in DMSO Calibration curve: First-order approximation line using standard pullulan manufactured by Shodex

[0223] The following is an example of the effect of catalyst type on the degree of delignification. [Reference Data 1] (A) 100 mg of cedar wood flour (lignin content 36%) as biomass, (B) 0.2 mL of 20% hydrogen peroxide as peroxide, (C) 26 μmol of acids with various acid dissociation constants (pKa) as acids, and (E) 0.8 mL of toluene as solvent were mixed and reacted at 60°C for 24 hours. The reaction suspension was filtered through filter paper, and the composition on the filter paper was washed with water and freeze-dried. The amount of lignin remaining in the resulting cellulose-containing composition (% vs. the bone-dry weight of the starting cedar wood flour) was measured, and the results were plotted against the acid dissociation constants (pKa) of the acids used (Figure 14). These results indicate that acids with a relatively low pKa, i.e., strong acids, are effective for delignification. In this reaction, the acid acts as a catalyst, so it is understandable that a strong acid has a greater effect, but using an acid with a pKa higher than a certain level actually slows down delignification. Therefore, for example, to keep the amount of residual lignin at 15% or less, it is preferable that the pKa be -7.5 < pKa < -0.4. The pKa varies greatly depending on the type of acid, and sulfonic acid is a typical example of an acid that falls within this pKa range.

[0224] [Reference Data 2] (A) 100 mg of cedar wood flour (lignin content 36%) as biomass, (B) 0.2 mL of 20% hydrogen peroxide solution as peroxide, (C) various toluene / water partition coefficients (logP トルエン / 水 26 μmol of sulfonic acid having the formula (E) and 0.8 mL of toluene as a solvent were mixed and reacted at 60° C. for 24 hours. The reaction mixture was filtered through filter paper, and the composition on the filter paper was washed with water and then freeze-dried. The amount of lignin remaining in the resulting cellulose-containing composition (% relative to the bone-dry weight of the raw cedar wood flour) was measured, and the toluene / water partition coefficient (logP トルエン / 水 ) (Figure 15). From this result, it is clear that the toluene / water partition coefficient (logP トルエン / 水 ), i.e., a highly hydrophobic acid, is effective for delignification. This is because acids with a highly hydrophobic moiety have a high affinity for hydrophobic lignin. From Figure 15, for example, acids with a toluene / water partition coefficient (logP トルエン / 水 ) is preferably −2.8 or more.

[0225] An example of investigating the effect of the solvent type on the degree of delignification is shown below.

[0226] [Reference Data 3] (A) 100 mg of cedar wood flour as biomass, (B) 0.3 mL of 30% hydrogen peroxide as peroxide, (D) 10 mg of 1H-imidazolium, 1-methyl-3-(3-sulfopropyl)-, 4-methylbenzenesulfonate as acid, (E) various octanol / water partition coefficients (logP) as solvents. オクタノール / 水 ) and 0.7 mL of a solvent having the formula (I) was mixed, and the mixture was reacted at 60°C for 24 hours. The reaction mixture suspension was filtered through filter paper, and the composition on the filter paper was washed with water and then freeze-dried. The amount of lignin remaining in the resulting cellulose-containing composition (% relative to the bone-dry weight of the raw cedar wood flour) was measured, and the octanol / water partition coefficient (logP オクタノール / 水 ) was plotted against the octanol / water partition coefficient (logP オクタノール / 水 It can be seen that when a solvent having a β-glucan value of 0.5 or more is used, lignin can be decomposed and eluted extremely effectively.

[0227] [Reference Data 4] (A) 100 mg of cedar wood flour as biomass, (B) 0.2 mL of 30% hydrogen peroxide as peroxide, (D) 5 mg of p-toluenesulfonic acid monohydrate as acid, (E) various octanol / water partition coefficients (logP オクタノール / 水 ) and 0.8 mL of a solvent having the formula (I) was mixed, and the mixture was reacted at 60°C for 24 hours. The reaction mixture suspension was filtered through filter paper, and the composition on the filter paper was washed with water and then freeze-dried. The amount of lignin remaining in the resulting cellulose-containing composition (% relative to the bone-dry weight of the raw cedar wood flour) was measured, and the octanol / water partition coefficient (logP オクタノール / 水 ) (Figure 17). From this result, the octanol / water partition coefficient (logP オクタノール / 水 It can be seen that the higher the solvent's octanol / water partition coefficient, the more effective the delignification, and that lignin can be decomposed and eluted effectively using a solvent with an octanol / water partition coefficient of 0.5 or more.

[0228] The effects of such solvents are considered as follows: (1) Octanol / water partition coefficient (log P オクタノール / 水 In solvents with high affinity for hydrogen peroxide and substantially no miscibility with aqueous hydrogen peroxide, the hydrogen peroxide is not diluted by the solvent, and highly reactive acid-derived peroxides (e.g., persulfonic acids) are efficiently generated. (2) The reactive species generated, such as peroxides, can access the lignin via the solvent, which has a high affinity for hydrophobic lignin, and effectively decompose and elute the lignin.

Claims

1. The method comprises a step of mixing lignocellulose-containing biomass as component (A), a peroxide and / or peracid as component (B), at least one of an acid and a compound represented by the following formula (c-1) as component (C), and a solvent as component (E), to delignify the lignocellulose, [In the formula (c-1), ring Z represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring, and R 7 represents a divalent hydrocarbon group, m represents an integer of 0 or greater, and n represents an integer of 1 or greater.] A method for producing a cellulose-containing composition, wherein the acid in component (C) is an acid having an acid dissociation constant (pKa) of −7.5<pKa<−0.

4.

2. The method comprises a step of mixing biomass containing lignocellulose as component (A), a peroxide and / or peracid as component (B), an acid different from the peroxide and the peracid as component (D), and a solvent as component (E) to delignify the lignocellulose, wherein the solvent as component (E) has an octanol / water partition coefficient (logP オクタノール / 水 ) is 0.5 or more, or is at least one solvent selected from the group consisting of hydrocarbon solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, and ester solvents.

3. In the component (C) and the component (D), the toluene / water partition coefficient (logP トルエン / 水 3. The method for producing a cellulose-containing composition according to claim 1, wherein the cellulose content is -2.8 or more.

4. A method for producing a cellulose-containing composition according to claim 1 or 2, wherein the delignification step is carried out at a temperature of 100°C or less.

5. A method for producing a cellulose-containing composition according to claim 1 or 2, further comprising a step of separating the suspension containing the cellulose-containing composition produced in the delignification step into a phase containing cellulose as the main solid content and a phase derived from the biomass and solubilized or liquefied in a solvent.

6. A method for producing a cellulose-containing composition according to claim 1 or 2, wherein the average fiber width of the cellulose-containing fibers contained in the cellulose-containing composition is 1 μm or more.

7. A method for producing a cellulose-containing composition according to claim 1 or 2, further comprising one or more steps of esterifying, etherifying, azidizing, or amminating a portion of the hydroxyl groups of the cellulose contained in the cellulose-containing composition during the delignification step or a subsequent step.

8. A method for producing a cellulose nanofiber-containing composition, comprising a step of subjecting the cellulose-containing composition obtained by the method for producing a cellulose-containing composition described in claim 1 or 2 to a micronization treatment until the average fiber width of the cellulose-containing fibers contained in the cellulose-containing composition is 100 nm or less, thereby obtaining cellulose nanofibers.

9. A method for producing a cellulose nanofiber-containing composition according to claim 8, wherein the cellulose nanofibers have an average fiber width of 10 nm or less.

10. A method for producing a cellulose nanofiber-containing composition according to claim 8, wherein the micronization treatment is carried out using a high-pressure homogenizer.

11. A method for producing a cellulose nanofiber-containing composition according to claim 8, wherein the cellulose nanofibers are produced without chemically modifying the cellulose.

12. A cellulose-containing composition that, when subjected to high-pressure homogenizer treatment under the following conditions, produces cellulose nanofibers with an average fiber width of 100 nm or less after 10 or fewer treatments, or when made into an aqueous dispersion with a solids concentration of 0.1% by mass, produces cellulose nanofibers with a light transmittance of 50% or more as measured using a spectrophotometer at a wavelength of 660 nm and an optical path length of 1 cm. (Conditions for high-pressure homogenizer treatment) The cellulose-containing composition to be treated with a high-pressure homogenizer is an aqueous dispersion with a solids concentration of 0.3 to 1.0% by mass. The treatment pressure is within the range of 150 to 245 MPa, the nozzle diameter is 0.1 to 0.15 mm, the treatment temperature is 25°C ± 25°C, and the number of treatments is 10 or fewer.

13. A cellulose-containing composition that, when subjected to high-pressure homogenizer treatment under the following conditions, produces cellulose nanofibers with an average fiber width of 100 nm or less after 10 or fewer treatments, or when made into an aqueous dispersion with a solids concentration of 0.1% by mass, produces cellulose nanofibers with a light transmittance of 50% or more as measured using a spectrophotometer at a wavelength of 660 nm and an optical path length of 1 cm. (Conditions for high-pressure homogenizer treatment) The cellulose-containing composition to be treated with a high-pressure homogenizer is an aqueous dispersion with a solids concentration of 0.3 to 1.0% by mass. The treatment pressure is 100 MPa, the nozzle diameter is 0.1 to 0.15 mm, the treatment temperature is 25°C ± 25°C, and the number of treatments is 10 or fewer.

14. The cellulose-containing composition according to claim 12 or 13, wherein the average fiber width of the cellulose-containing fibers contained in the cellulose-containing composition is 1 μm or more and 100 μm or less.

15. A cellulose-containing composition according to claim 12 or 13, wherein the cellulose nanofibers have an average fiber width of 10 nm or less.

16. The cellulose-containing composition according to claim 12 or 13, wherein the cellulose contained in the cellulose-containing composition has not been subjected to chemical modification and / or regeneration treatment.

17. The cellulose-containing composition according to claim 16, having a weight-average molecular weight of 200,000 or more.

18. Cellulose nanofibers that have not been chemically modified and / or regenerated and have an average fiber width of 10 nm or less.

19. Cellulose nanofiber that has not been chemically modified and / or regenerated, and when dispersed in water with a solids concentration of 0.1% by mass, has a light transmittance of 50% or more when measured using a spectrophotometer at a wavelength of 660 nm and an optical path length of 1 cm.

Images