WO2018143149A1

WO2018143149A1 - Production method of dried cellulose nanofibers

Info

Publication number: WO2018143149A1
Application number: PCT/JP2018/002846
Authority: WO
Inventors: 藤槻薫麗; 半埜賢治
Original assignee: 株式会社片山化学工業研究所; 日本製紙株式会社
Priority date: 2017-02-03
Filing date: 2018-01-30
Publication date: 2018-08-09
Also published as: JP2021143343A; JPWO2018143149A1; JP7270194B2; JP6931837B2

Abstract

A production method of dried cellulose nanofibers (CNFs) having sufficient redispersibility, and a method capable of improving redispersibility of CNFs are provided. The invention relates to: a dried CNF production method which involves mixing anion-modified CNFs and a redispersibility improving agent to obtain an aqueous suspension of anion-modified CNFs, and drying the aqueous suspension to obtain dried CNFs, wherein the redispersibility improving agent is selected from the group consisting of sugars with a molecular weight of less than or equal to 50,000, low molecular weight polypeptides, amino acids, and low molecular weight polyvinyl alcohol; and a CNF redispersibility improvement method which involves mixing anion-modified CNF and a redispersibility improving agent to obtain an aqueous suspension of anion-modified CNF, and drying the aqueous suspension, wherein the redispersibility improving agent is selected from the group consisting of sugars with a molecular weight less than or equal to 50,000, low molecular weight polypeptides, amino acids, and low molecular weight polyvinyl alcohol.

Description

Method for producing dry cellulose nanofiber

The present disclosure relates to a method for producing dry cellulose nanofibers and a method for improving the redispersibility of dry cellulose nanofibers.

Cellulose nanofiber (CNF) is a plant-derived fiber refined to a fiber diameter of about several nm to several hundred nm. CNF has a small environmental load and has various characteristics such as light weight, high strength, high gas barrier property, small dimensional deformation due to heat, high specific surface area, high transparency, and high viscosity in water. For this reason, CNF is expected to be used not only in automobile parts and food packaging materials but also in a wide range of fields such as foods, pharmaceuticals and cosmetics.

CNF is usually produced as a low concentration aqueous dispersion (wet state). However, in the case of an aqueous dispersion, there are problems such as high transportation and storage costs and contamination with bacteria. For this reason, a method of drying CNF has been proposed (for example, Patent Document 1).

WO2015 / 107995

The dried CNF is usually used after being redispersed in a dispersion medium such as water. When performing this redispersion, there may be a problem that CNF is not sufficiently redispersed. In particular, CNF obtained by drying a transparent CNF solution, especially dried anion-modified CNF, particularly 2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) oxidized CNF has low redispersibility and transparency. There is a problem of not recovering. For this reason, a new method capable of drying CNF while maintaining sufficient redispersibility is demanded.

In one aspect, the present disclosure provides a method for producing dry CNF with improved redispersibility, particularly a method for producing dry CNF with improved transparent dispersibility during redispersion. In one aspect, the present disclosure provides a method that can improve the redispersibility of CNF. Moreover, this indication provides the method of making it possible to improve the transparent dispersibility at the time of re-dispersion of dry TEMPO oxidation CNF in one aspect | mode. In the present disclosure, “transparent dispersibility at the time of redispersion” means that, in one or a plurality of embodiments, CNF is dispersed in a dispersion medium at a level close to microfibril units or microfibril units, and is dispersed in a highly transparent state. That means.

In one aspect, the present disclosure provides an aqueous suspension of anion-modified cellulose nanofibers by mixing an anion-modified cellulose nanofiber and a redispersibility improver, and drying the aqueous suspension to dry cellulose. A dry cellulose nanofiber comprising: obtaining a nanofiber, wherein the redispersibility improving agent is selected from the group consisting of a saccharide having a molecular weight of 50,000 or less, a low molecular weight polypeptide, an amino acid, and a low molecular weight polyvinyl alcohol. It relates to the manufacturing method.

In one aspect, the present disclosure includes mixing an anion-modified cellulose nanofiber and a redispersibility improver to obtain an aqueous suspension of the anion-modified cellulose nanofiber, and drying the aqueous suspension. The redispersibility improving agent relates to a method for improving redispersibility of cellulose nanofibers selected from the group consisting of sugars having a molecular weight of 50,000 or less, low molecular weight polypeptides, amino acids, and low molecular weight polyvinyl alcohol.

In one aspect, the present disclosure provides an agent for improving or improving the redispersibility of dry cellulose nanofibers in a dispersion medium, in particular, redispersibility, a saccharide having a molecular weight of 50,000 or less, a low molecular weight poly The present invention relates to a redispersibility improving agent comprising at least one selected from the group consisting of peptides, amino acids, and low molecular weight polyvinyl alcohol.

In one aspect, the present disclosure is a dry composition containing anion-modified cellulose nanofibers and a redispersibility improver, wherein the redispersibility improver is a saccharide having a molecular weight of 50,000 or less, a low molecular weight polypeptide, The present invention relates to a dry composition comprising at least one selected from the group consisting of amino acids and low molecular weight polyvinyl alcohol.

According to the present disclosure, a method for producing dry CNF with improved redispersibility, particularly a method for producing dry CNF with improved transparent dispersibility during redispersion can be provided. Further, according to the present disclosure, it is possible to provide a method capable of improving or improving the redispersibility of CNF, particularly a method capable of improving or improving the transparent dispersibility during redispersion. According to the present disclosure, it is preferable to provide a method for producing dry TEMPO-oxidized CNF having improved transparent dispersibility during redispersion and a method capable of improving the transparent dispersibility during redispersion of dry TEMPO-oxidized CNF. In addition, according to the present disclosure, it is possible to provide a method for producing dry carboxymethyl (CM) -modified CNF having improved dispersibility during re-dispersion and a method capable of improving the dispersibility during re-dispersion of dry C-methyl CNF. Further, according to the present disclosure, it is possible to provide a method for producing dry phosphate esterified CNF with improved dispersibility during redispersion and a method capable of improving the transparent dispersibility during redispersion of dry phosphate esterified CNF. .

The present disclosure improves the redispersibility of dry CNF obtained by drying an aqueous suspension in which anion-modified CNF is mixed with a low molecular weight saccharide such as cyclodextrin or low molecular weight polycarboxymethylcellulose (CMC). Based on the knowledge that can be done. In addition, when the anion-modified CNF is TEMPO-oxidized CNF, mixing with the above low molecular weight saccharide and drying improves the transparent dispersibility during redispersion of the dry CNF, and the resulting dry CNF is dispersed in water or the like. It is based on the knowledge that a highly transparent dry CNF redispersion liquid can be obtained by contacting with a medium.

The present disclosure is based on the finding that the redispersibility of the obtained dry CNF can be improved by drying an aqueous suspension in which anion-modified CNF and a low molecular weight polypeptide or amino acid are mixed. In addition, when the anion-modified CNF is TEMPO-oxidized CNF, when mixed with a low molecular weight polypeptide or amino acid and dried, the transparent dispersibility at the time of redispersion of the dry CNF is improved, and the obtained dry CNF is converted into water or the like. It is based on the knowledge that a highly transparent dry CNF redispersion liquid can be obtained when brought into contact with a dispersion medium.

The present disclosure is based on the finding that the redispersibility of the obtained dry CNF can be improved by drying an aqueous suspension obtained by mixing anion-modified CNF and low molecular weight polyvinyl alcohol (PVA). Further, when the anion-modified CNF is TEMPO-oxidized CNF, when mixed with a low molecular weight PVA and dried, the transparent dispersibility during re-dispersion of the dried CNF is improved, and the resulting dried CNF is mixed with a dispersion medium such as water. This is based on the knowledge that a highly transparent dry CNF redispersion liquid can be obtained by contact.

The present disclosure shows that low molecular weight sugars such as cyclodextrin and low molecular weight CMC, low molecular weight polypeptides, amino acids, and low molecular weight PVA can be used as a dispersibility improving agent when redispersing dry CNF. based on. In the present disclosure, “molecular weight of the redispersibility improver” refers to an average molecular weight, preferably a weight average molecular weight, when the redispersibility improver is a polymer. In the present disclosure, the redispersibility improving agent may be used alone or in combination of two or more.

“Improvement or improvement of redispersibility” in the present disclosure is obtained by mixing dry CNF obtained by the dry CNF production method of the present disclosure with a dispersion medium such as water in one or a plurality of embodiments. A CNF dispersion obtained by mixing an anion-modified CNF in a state where the CNF dispersion is dispersed in water (wet state) as it is (without adding a chemical agent) and a dispersion medium. Compared with a liquid (or CNF suspension), it means that the turbidity is low or the amount of undispersed CNF pieces or gelled products is small. In the present disclosure, “improvement or improvement of transparent dispersibility during redispersion” means that in one or a plurality of embodiments, CNF is dispersed in a dispersion medium at a level close to microfibril units or microfibril units, and is in an undispersed state. It means that transparency is higher than CNF pieces or gelled products are hardly observed. In one or a plurality of embodiments, the dry CNF obtained by the dry CNF production method of the present disclosure is mixed with a dispersion medium such as water and stirred, and the CNF is separated at a level close to a microfibril unit or a microfibril unit. Therefore, dry CNF can be dispersed in the dispersion medium in a highly transparent state. According to the dry CNF obtained by the production method of the present disclosure, a highly transparent dry CNF re-dispersion liquid can be obtained in one or a plurality of embodiments. “High transparency” in the present disclosure includes high light transmittance in one or more embodiments.

Japanese Patent Application Laid-Open No. 9-165402 discloses a method of adding a third component (components other than BC and water) to an aqueous suspension of bacterial cellulose (BC), followed by drying, thereby condensing BC after drying. It is disclosed that various properties such as dispersibility and sedimentation degree are restored to the state before drying. However, bacterial cellulose is a naturally occurring cellulose fiber produced from bacteria and has no charge. On the other hand, the anion-modified CNF of the present disclosure is a cellulose nanofiber obtained by chemical treatment as described later, and has a charge on the surface of the cellulose fiber by the chemical treatment. For this reason, the anion-modified CNF and bacterial cellulose of the present disclosure are completely different. Furthermore, this document restores the original disaggregated state, specifically, a state in which a large amount of liquid component is included in the surface of the fine fibers or the voids of the network structure constituted by the fine fibers. It is intended. For this reason, the regenerated product obtained by the method of the same literature (the product obtained by adding water to the dried product of bacterial cellulose to restore the wet state) is a white turbid body. In contrast, the dry CNF redispersed liquid obtained by the present disclosure separates and disperses the fibers (CNF) separately, and thus a highly transparent CNF redispersed liquid is obtained. Therefore, the method disclosed in Japanese Patent Laid-Open No. 9-165402 is a method that is completely different from the method of the present disclosure in terms of not only the object to be processed but also the technical idea.

[Anion-modified CNF]
In the present disclosure, “anion-modified CNF” refers to cellulose nanofibers obtained by chemically treating cellulose, and more specifically, nanofibers are obtained by fibrillating cellulose fibers whose fiber surfaces are chemically treated. It refers to fine fibers (nanofibers). In one or a plurality of embodiments, the anion-modified CNF in the present disclosure has a charge on the surface of the cellulose fiber by chemical treatment. In one or a plurality of embodiments, the anion-modified CNF in the present disclosure does not include naturally-derived cellulose nanofibers such as bacterial cellulose produced from bacteria.

Examples of the chemical treatment include carboxymethyl (CM) treatment, carboxylation (oxidation) treatment, phosphate esterification treatment and the like in one or a plurality of embodiments.

[Carboxymethyl (CM)]
Examples of the method for carboxymethylation of the cellulose raw material or the defibrated cellulose fiber include a method in which cellulose as a bottoming raw material is mercerized and then etherified. In the carboxymethylation reaction, a solvent is usually used. Examples of the solvent include water, alcohol (eg, lower alcohol), and mixed solvents thereof. Specific examples of the lower alcohol include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, isobutanol, and tertiary butanol. As for the mixing ratio of the lower alcohol in the mixed solvent, the lower limit is usually 60% by weight or more, and the upper limit is usually 95% by weight or less, preferably 60% by weight to 95% by weight. The amount of the solvent is usually 3 times or more by weight based on the cellulose raw material or defibrated cellulose fiber. Moreover, although the upper limit of the quantity of a solvent is not specifically limited, Usually, it is 20 weight times or less with respect to a cellulose raw material or a defibrated cellulose fiber. Therefore, the amount of the solvent is preferably 3 to 20 times by weight with respect to the cellulose raw material or defibrated cellulose fiber.

Mercerization is usually performed by mixing a cellulose raw material or defibrated cellulose fiber and a mercerizing agent. Examples of mercerizing agents include alkali metal hydroxides (eg, sodium hydroxide, potassium hydroxide).

The lower limit of the amount of the mercerizing agent used is usually 0.5 times mol or more per anhydroglucose residue of cellulose raw material or defibrated cellulose fiber. Moreover, an upper limit is 20 times mole or less normally. Therefore, the amount of the mercerizing agent used is preferably 0.5 to 20 times mol per anhydroglucose residue of the cellulose raw material or defibrated cellulose fiber.

The lower limit of the mercerization reaction temperature is usually 0 ° C or higher, preferably 10 ° C or higher. The upper limit is usually 70 ° C. or lower, preferably 60 ° C. or lower. Therefore, the reaction temperature for mercerization is usually 0 ° C. to 70 ° C., preferably 10 ° C. to 60 ° C.

The lower limit of the mercerization reaction time is usually 15 minutes or longer, preferably 30 minutes or longer. The lower limit is usually 8 hours or less, preferably 7 hours or less. Therefore, the reaction time for mercerization is usually 15 minutes to 8 hours, preferably 30 minutes to 7 hours.

The etherification reaction is usually performed by adding a carboxymethylating agent to the reaction system after mercerization. Examples of the carboxymethylating agent include sodium monochloroacetate.

The lower limit of the addition amount of the carboxymethylating agent is usually 0.05 times mole or more per glucose residue of the cellulose raw material or defibrated cellulose fiber. The upper limit is usually 10.0 times mol or less. Accordingly, the addition amount of the carboxymethylating agent is usually 0.05 times to 10.0 times moles per glucose residue of the cellulose raw material or defibrated cellulose fiber. The lower limit of the etherification reaction temperature is usually 30 ° C or higher, preferably 40 ° C or higher. An upper limit is 90 degrees C or less normally, Preferably it is 80 degrees C or less. Accordingly, the reaction temperature for etherification is usually 30 ° C. to 90 ° C., preferably 40 ° C. to 80 ° C.

The lower limit of the etherification reaction time is usually 30 minutes or longer, preferably 1 hour or longer. The upper limit is usually 10 hours or less, preferably 4 hours or less. Therefore, the reaction time for etherification is usually 30 minutes to 10 hours, preferably 1 hour to 4 hours.

As a measuring method of the carboxymethyl substitution degree per glucose unit of carboxymethylated cellulose fiber or carboxymethylated cellulose nanofiber, for example, it can be obtained by the following method. That is, 1) About 2.0 g of carboxymethylated cellulose fiber or carboxymethylated cellulose nanofiber (absolutely dried) is precisely weighed and placed in a 300 mL conical stoppered Erlenmeyer flask. 2) Add 100 mL of special concentrated nitric acid solution to 1000 mL of methanol, add 100 mL of methanol solution of nitric acid, and shake for 3 hours to convert carboxymethyl cellulose salt (CM-modified cellulose salt: eg Na-CMC) into H-CM-converted cellulose. (H-CMC). 3) Weigh accurately 1.5 g to 2.0 g of H-CM-modified cellulose (absolutely dry) and put into a 300 mL Erlenmeyer flask with a stopper. 4) Wet the H-CM cellulose with 15 mL of 80% methanol, add 100 mL of 0.1N NaOH, and shake at room temperature for 3 hours. 5) Back titrate excess NaOH with 0.1N H ₂ SO ₄ using phenolphthalein as indicator. 6) The degree of carboxymethyl substitution (DS) is calculated by the following formula:
A = [(100 × F ′ − (0.1 N H ₂ SO ₄ ) (mL) × F) × 0.1] / (absolute dry mass of H-CM cellulose (g))
DS = 0.162 × A / (1-0.058 × A)
A: Amount of 1N NaOH required for neutralizing 1 g of H-CM cellulose (mL)
F ′: Factor of 0.1N NaOH F: Factor of 0.1N H ₂ SO ₄

In the present disclosure, “carboxymethylated cellulose”, which is a kind of modified cellulose used for the preparation of modified CNF, means that at least a part of the fibrous shape is maintained even when dispersed in water. Therefore, it is distinguished from carboxymethyl cellulose (CMC) which is a kind of water-soluble polymer described later. When an aqueous dispersion of “carboxymethylated cellulose” is observed with an electron microscope, a fibrous substance can be observed. On the other hand, even when an aqueous dispersion of carboxymethyl cellulose, which is a kind of water-soluble polymer, is observed, a fibrous substance is not observed. In addition, “carboxymethylated cellulose” can observe the peak of cellulose I-type crystals when measured by X-ray diffraction, but cellulose I-type crystals are not observed in the water-soluble polymer carboxymethylcellulose.

[Carboxylation]
In the present disclosure, when carboxylated (oxidized) cellulose is used as the modified cellulose, carboxylated cellulose (also referred to as oxidized cellulose) can be obtained by carboxylating (oxidizing) the above cellulose raw material by a known method. . Although not particularly limited, at the time of carboxylation, the amount of carboxyl groups should be adjusted to 0.6 mmol / g to 2.0 mmol / g with respect to the absolute dry mass of anion-modified CNF. It is preferable to adjust the concentration to 1.0 mmol / g to 2.0 mmol / g.

As an example of a carboxylation (oxidation) method, a cellulose raw material is oxidized in water using an oxidizing agent in the presence of an N-oxyl compound and a compound selected from the group consisting of bromide, iodide, or a mixture thereof. A method can be mentioned. By this oxidation reaction, the primary hydroxyl group at the C6 position of the glucopyranose ring on the cellulose surface is selectively oxidized, and the cellulose fiber having an aldehyde group and a carboxyl group (—COOH) or carboxylate group (—COO—) on the surface. Can be obtained. The concentration of cellulose during the reaction is not particularly limited, but is preferably 5% by mass or less.

N-oxyl compound refers to a compound capable of generating a nitroxy radical. As the N-oxyl compound, any compound can be used as long as it promotes the target oxidation reaction. Examples include 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) and its derivatives (eg, 4-hydroxy TEMPO).

The amount of N-oxyl compound used is not particularly limited as long as it is a catalytic amount capable of oxidizing cellulose as a raw material. For example, with respect to 1 g of absolutely dry cellulose, 0.01 mmol to 10 mmol is preferable, 0.01 mmol to 1 mmol is more preferable, and 0.05 mmol to 0.5 mmol is more preferable. Further, it is preferably about 0.1 mmol / L to 4 mmol / L with respect to the reaction system.

Bromide is a compound containing bromine, and examples thereof include alkali metal bromide that can be dissociated and ionized in water. Further, an iodide is a compound containing iodine, and examples thereof include alkali metal iodide. The amount of bromide or iodide used can be selected as long as the oxidation reaction can be promoted. The total amount of bromide and iodide is, for example, preferably from 0.1 mmol to 100 mmol, more preferably from 0.1 mmol to 10 mmol, and even more preferably from 0.5 mmol to 5 mmol with respect to 1 g of absolutely dry cellulose.

As the oxidizing agent, known ones can be used, and for example, halogen, hypohalous acid, halous acid, perhalogen acid or salts thereof, halogen oxide, peroxide and the like can be used. Of these, sodium hypochlorite is preferable because it is inexpensive and has a low environmental impact. The amount of the oxidizing agent used is, for example, preferably 0.5 mmol to 500 mmol, more preferably 0.5 mmol to 50 mmol, further preferably 1 mmol to 25 mmol, and most preferably 3 mmol to 10 mmol with respect to 1 g of absolutely dry cellulose. Further, for example, 1 to 40 mol is preferable with respect to 1 mol of the N-oxyl compound.

The carboxylation (oxidation) of cellulose allows the reaction to proceed efficiently even under relatively mild conditions. Therefore, the reaction temperature is preferably 4 ° C. to 40 ° C., and may be room temperature of about 15 ° C. to 30 ° C. As the reaction proceeds, a carboxyl group is generated in the cellulose, so that the pH of the reaction solution is reduced. In order to make the oxidation reaction proceed efficiently, an alkaline solution such as an aqueous sodium hydroxide solution is added to maintain the pH of the reaction solution at about 8 to 12, preferably about 10 to 11. The reaction medium is preferably water because it is easy to handle and hardly causes side reactions.

The reaction time in the oxidation reaction can be appropriately set according to the progress of oxidation, and is usually 0.5 to 6 hours, for example, about 0.5 to 4 hours.

Moreover, the oxidation reaction may be carried out in two stages. For example, by oxidizing the oxidized cellulose obtained by filtration after the completion of the first-stage reaction again under the same or different reaction conditions, the efficiency is not affected by the reaction inhibition by the salt generated as a by-product in the first-stage reaction. Can be oxidized well.

Another example of the carboxylation (oxidation) method is a method of oxidizing by contacting a gas containing ozone and a cellulose raw material. By this oxidation reaction, at least the 2-position and 6-position hydroxyl groups of the glucopyranose ring are oxidized and the cellulose chain is decomposed. The ozone concentration in the gas containing ozone is preferably 50 g / m ³ to 250 g / m ³ , and more preferably 50 g / m ³ to 220 g / m ³ . The amount of ozone added to the cellulose raw material is preferably 0.1 parts by mass to 30 parts by mass, and more preferably 5 parts by mass to 30 parts by mass when the solid content of the cellulose raw material is 100 parts by mass. . The ozone treatment temperature is preferably 0 ° C. to 50 ° C., more preferably 20 ° C. to 50 ° C. The ozone treatment time is not particularly limited, but is about 1 minute to 360 minutes, preferably about 30 minutes to 360 minutes. When the conditions for the ozone treatment are within these ranges, the cellulose can be prevented from being excessively oxidized and decomposed, and the yield of oxidized cellulose is improved. After the ozone treatment, an additional oxidation treatment may be performed using an oxidizing agent. The oxidizing agent used for the additional oxidation treatment is not particularly limited, and examples thereof include chlorine compounds such as chlorine dioxide and sodium chlorite, oxygen, hydrogen peroxide, persulfuric acid, and peracetic acid. For example, these oxidizing agents can be dissolved in a polar organic solvent such as water or alcohol to prepare an oxidizing agent solution, and a cellulose raw material can be immersed in the solution for additional oxidation treatment.

The amount of carboxyl groups in the oxidized cellulose can be adjusted by controlling the reaction conditions such as the amount of the oxidant added and the reaction time.

[Phosphate esterification]
As the modified cellulose, phosphorylated cellulose can be used. The said cellulose is obtained by the method of mixing the powder and aqueous solution of phosphoric acid type compound A with a cellulose raw material, and the method of adding the aqueous solution of phosphoric acid type compound A to the slurry of a cellulose raw material.

Examples of the phosphoric acid compound A include phosphoric acid, polyphosphoric acid, phosphorous acid, phosphonic acid, polyphosphonic acid, and esters thereof. These may be in the form of salts. Among these, a compound having a phosphate group is preferable because it is low in cost, easy to handle, and can improve the fibrillation efficiency by introducing a phosphate group into cellulose of the pulp fiber. Compounds having a phosphate group include phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate, sodium metaphosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, phosphorus Examples include tripotassium acid, potassium pyrophosphate, potassium metaphosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, ammonium metaphosphate, and the like. These can be used alone or in combination of two or more. Among these, phosphoric acid, phosphoric acid sodium salt, phosphoric acid potassium salt, phosphoric acid, from the viewpoint that phosphoric acid group introduction efficiency is high, is easy to be defibrated in the following defibrating process, and is industrially applicable. The ammonium salt is more preferred. In particular, sodium dihydrogen phosphate and disodium hydrogen phosphate are preferred. In addition, the phosphoric acid compound A is preferably used as an aqueous solution because the uniformity of the reaction is enhanced and the efficiency of introduction of phosphate groups is increased. The pH of the aqueous solution of the phosphoric acid compound A is preferably 7 or less because of the high efficiency of introducing phosphate groups, but is preferably pH 3 to 7 from the viewpoint of suppressing hydrolysis of pulp fibers.

The following method can be mentioned as an example of the manufacturing method of phosphoric ester cellulose. Phosphoric acid compound A is added to a cellulose raw material dispersion having a solid content concentration of 0.1% by mass to 10% by mass with stirring to introduce phosphate groups into the cellulose. When the cellulose raw material is 100 parts by mass, the addition amount of the phosphoric acid compound A is preferably 0.2 to 500 parts by mass, preferably 1 to 400 parts by mass as the amount of phosphorus element. Is more preferable. If the ratio of the phosphoric acid type compound A is more than the said lower limit, the yield of a fine fibrous cellulose can be improved more. However, if the upper limit is exceeded, the effect of improving the yield reaches its peak, which is not preferable from the viewpoint of cost.

At this time, in addition to the cellulose raw material and the phosphoric acid compound A, powders and aqueous solutions of other compounds B may be mixed. Compound B is not particularly limited, but a nitrogen-containing compound showing basicity is preferable. “Basic” as used herein is defined as an aqueous solution exhibiting a pink to red color in the presence of a phenolphthalein indicator, or an aqueous solution having a pH greater than 7. The basic nitrogen-containing compound used in the present disclosure is not particularly limited as long as the effect of the present disclosure is exhibited, but a compound having an amino group is preferable. For example, urea, methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, hexamethylenediamine and the like can be mentioned, but not particularly limited. Among these, urea which is easy to handle at low cost is preferable. The amount of compound B added is preferably 2 parts by mass to 1000 parts by mass, and more preferably 100 parts by mass to 700 parts by mass with respect to 100 parts by mass of the solid content of the cellulose raw material. The reaction temperature is preferably 0 ° C. to 95 ° C., more preferably 30 ° C. to 90 ° C. The reaction time is not particularly limited, but is about 1 to 600 minutes, more preferably 30 to 480 minutes. When the conditions of the phosphoric esterification reaction are within these ranges, it is possible to prevent the cellulose from being excessively phosphorylated and easily dissolved, and the yield of phosphorylated esterified cellulose is improved. From the viewpoint of suppressing hydrolysis of cellulose, it is preferable to heat-treat the obtained phosphoric esterified cellulose suspension at 100 ° C. to 170 ° C. Further, while water is contained in the heat treatment, it is preferably heated at 130 ° C. or lower, preferably 110 ° C. or lower, after removing water, it is preferably heat treated at 100 ° C. to 170 ° C.

The phosphate group substitution degree per glucose unit of the phosphorylated cellulose is preferably 0.001 to 0.40. By introducing a phosphate group substituent into cellulose, the celluloses are electrically repelled. For this reason, the cellulose which introduce | transduced the phosphate group can be nano-defibrated easily. In addition, when the phosphate group substitution degree per glucose unit is smaller than 0.001, nano-defibration cannot be sufficiently performed. On the other hand, if the degree of phosphate group substitution per glucose unit is greater than 0.40, it may swell or dissolve, and may not be obtained as a nanofiber. In order to efficiently perform defibration, it is preferable that the phosphoric esterified cellulose raw material obtained above is boiled and then washed with cold water.

[Defibration]
In the present disclosure, an apparatus for defibrating is not particularly limited, but a strong shearing force is applied to the aqueous dispersion of the modified cellulose by using an apparatus such as a high-speed rotation type, a colloid mill type, a high-pressure type, a roll mill type, or an ultrasonic type. It is preferable to apply. In particular, for efficient defibration, it is preferable to use a wet high-pressure or ultrahigh-pressure homogenizer that can apply a pressure of 50 MPa or more to the aqueous dispersion and can apply a strong shearing force. The pressure is more preferably 100 MPa or more, and further preferably 140 MPa or more. In addition, prior to defibration / dispersion treatment with a high-pressure homogenizer, if necessary, the modified cellulose may be pretreated using a known mixing, stirring, emulsifying, and dispersing device such as a high-speed shear mixer. Is possible. The number of treatments (passes) in the defibrating device may be one time, two times or more, and preferably two times or more.

In the modified cellulose dispersion treatment, the modified cellulose is usually dispersed in a solvent. Although a solvent will not be specifically limited if a modified cellulose can be disperse | distributed, For example, water, organic solvents (for example, hydrophilic organic solvents, such as methanol), and those mixed solvents are mentioned. Since it uses for foodstuffs, it is preferred that a solvent is water.

The solid content concentration of the modified cellulose in the dispersion is usually 0.1% by weight or more, preferably 0.2% by weight or more, more preferably 0.3% by weight or more. Thereby, the liquid quantity with respect to the quantity of a cellulose fiber raw material becomes an appropriate quantity, and is efficient. The upper limit is usually 10% by weight or less, preferably 6% by weight or less. Thereby, fluidity | liquidity can be hold | maintained.

In the present disclosure, the fiber width of the anion-modified CNF is, in one or more embodiments, about 1 nm to 500 nm or 2 nm to 100 nm, preferably 1 nm to less than 20 nm, 2 nm to 15 nm, or 3 nm to 5 nm. . The average aspect ratio of anion-modified CNF is usually 100 or more. The upper limit of the average aspect ratio is not particularly limited, but is usually 1000 or less. The average aspect ratio can be calculated by the following formula:
Average aspect ratio = average fiber length / average fiber diameter

Examples of the cellulose raw material include plant materials, animal materials, and algae in one or more embodiments. In one or a plurality of embodiments, examples of the plant material include wood, bamboo, hemp, jute, kenaf, cloth, pulp, recycled pulp, and waste paper. Examples of the pulp include kraft pulp (KP), sulfate pulp (SP), dissolved sulfite pulp (DSP), dissolved kraft pulp (DKP), powdered cellulose, and microcrystalline cellulose powder in one or more embodiments. Examples of the animal material include squirts in one or a plurality of embodiments.

[Method for producing dry CNF]
In one aspect, the present disclosure includes mixing an anion-modified CNF and a redispersibility improver to obtain an aqueous suspension of the anion-modified CNF, and drying the aqueous suspension to obtain a dry CNF. The present invention relates to a method for producing dry CNF (a method for producing dry CNF of the present disclosure). According to the method for producing dry CNF of the present disclosure, in one or a plurality of embodiments, film-like dry CNF and / or powder-like dry CNF having sufficient transparent dispersibility upon redispersion can be obtained. In one or a plurality of embodiments, the method for producing dry CNF of the present disclosure can be preferably used for TEMPO-oxidized CNF among anion-modified CNFs. According to the method for producing dry CNF of the present disclosure, in one or a plurality of embodiments, the redispersibility of a dried product of TEMPO-oxidized CNF (dry CNF) can be improved or improved. Dispersibility can be improved or improved.
Moreover, the manufacturing method of the dry CNF of this indication can be utilized for CCM CNF in one or some embodiment. According to the method for producing dry CNF of the present disclosure, in one or a plurality of embodiments, the dispersibility at the time of redispersion of the dried product of CCM CNF (dry CNF) can be improved or improved.
Moreover, the manufacturing method of the dry CNF of this indication can be preferably utilized for phosphate ester CNF in anion modified CNF in one or some embodiment. According to the method for producing dry CNF of the present disclosure, in one or a plurality of embodiments, the redispersibility of a dried product of phosphoesterified CNF (dry CNF) can be improved or improved. The transparent dispersibility of can be improved or improved.

According to the method for producing dry CNF of the present disclosure, in one or a plurality of embodiments, dry CNF having improved redispersibility can be obtained, and in particular, dry CNF having improved transparent dispersibility during redispersion can be obtained. Obtainable. In one or more embodiments that are not particularly limited, the obtained dry CNF may have sufficient transparent dispersibility when redispersed. “Having sufficient transparent dispersibility when redispersed” means that, in one or more embodiments, the transparency and re-dispersion to the dispersion medium at the same or comparable level as the anion-modified CNF suspension before drying. It has dispersibility. In one or a plurality of embodiments, the obtained dry CNF is used in various chemical products, foods, cosmetics, pharmaceuticals, beverages, reinforcing materials (including paper), absorbent products such as diapers, heat insulating materials, automobile members, paints, and the like. It can be used for agricultural chemicals, construction, batteries, household goods, water treatment, or cleaning agents.

The redispersibility improving agent in the present disclosure includes, in one or more embodiments, low molecular weight saccharides, low molecular weight polypeptides, amino acids, and low molecular weight PVA.

<Low molecular weight sugars>
In one or a plurality of embodiments, the method for producing dry CNF of the present disclosure includes mixing an anion-modified CNF and a low molecular weight saccharide to obtain an aqueous suspension of the anion-modified CNF, and the obtained aqueous suspension. Including drying the liquid.

In the present disclosure, “low molecular weight saccharide” refers to a saccharide having a molecular weight of 50,000 or less. Examples of the saccharide include monosaccharides, disaccharides, oligosaccharides, and polysaccharides in one or more embodiments. In one or more embodiments, the molecular weight of the low molecular weight saccharide is 50,000 or less, 20,000 or less, 15,000 or less, 10,000 or less, 5000 or less, 3000 or less, 2000 or less, or 200 or less, Or 150 or more.

Examples of monosaccharides include glucose and the like in one or more embodiments. The molecular weight of the monosaccharide is 150 or more or 200 or less in one or more embodiments.

Examples of disaccharides include maltose and lactose in one or more embodiments. In one or more embodiments, the molecular weight of the disaccharide is 200 or more, or 400 or less, 380 or less, 360 or less, or 350 or less.

Oligosaccharides include cyclodextrin in one or more embodiments. In one or more embodiments, the molecular weight (weight average molecular weight) of the oligosaccharide is 400 or more, 600 or more, 800 or more, or 900 or more, or 5000 or less, 4000 or less, 3000 or less, or 2000 or less. Examples of cyclodextrins include α-cyclodextrin (natural molecular weight: 973), β-cyclodextrin (natural molecular weight: 1135), and γ-cyclodextrin (natural molecular weight: 1297). In one or more embodiments, the cyclodextrin may be a natural cyclodextrin or a chemically modified cyclodextrin (cyclodextrin derivative). As the chemically modified cyclodextrin (cyclodextrin derivative), in one or more embodiments, hydroxypropylated cyclodextrin, acetylated cyclodextrin, triacetylated cyclodextrin, methylated cyclodextrin, monochlorotriazinated cyclodextrin, amino Cyclodextrin, ethylene diaminated cyclodextrin and the like.

Among the above low molecular weight saccharides, α-cyclodextrin and β-cyclodextrin derivatives having a molecular weight of 3000 or less or 2000 or less from the viewpoint of obtaining good redispersibility, in particular, good transparent redispersibility upon redispersion. Alternatively, γ-cyclodextrin or glucose is preferable. Furthermore, α-cyclodextrin, β-cyclodextrin derivative, or γ-cyclodextrin is more preferable because it does not inhibit the properties (thixotropic properties, viscosity, etc.) of anion-modified CNF.

Examples of polysaccharides include dextrin and low molecular weight CMC in one or more embodiments.

In one or a plurality of embodiments, the molecular weight of dextrin is 50,000 or less, 20,000 or less, 17,000 or less, 15,000 or less, 13,000 or less, 120,000 or less, 11,000 or less, or 10,000. 000 or less, or 200 or more, 500 or more, 1,000 or more, 2,000 or more, 3,000 or more, 4,000 or more, 5,000 or more, or 6,000 or more.

Examples of the low molecular weight CMC include CMC having a molecular weight of 20,000 or less. The molecular weight of the low molecular weight CMC is 20,000 or less, 15,000 or less, or 200 or more in one or more embodiments.

The degree of etherification (carboxymethyl group substitution) of CMC is not particularly limited, and may be 0.55 to 1.6 or 0.65 to 1.1 in one or more embodiments.

In one or a plurality of embodiments, the method for producing dry CNF according to the present disclosure includes mixing an anion-modified CNF in a wet state (dispersed in water) and a low molecular weight saccharide. Thereby, an aqueous suspension containing anion-modified CNF and a low molecular weight saccharide can be obtained.

The blending ratio of the low molecular weight saccharide to the anion-modified CNF (absolute dry solid content, 100 parts by mass) is 5 parts by mass or more, 5 parts by mass to 500 parts by mass, 5 parts by mass to 400 parts by mass in one or more embodiments. Part by mass, 5 parts by mass to 300 parts by mass or 10 parts by mass to 200 parts by mass, and preferably 30 parts by mass to 350 parts by mass or 30 parts by mass to 150 parts by mass.

When the anion-modified CNF is a carboxylated CNF such as TEPO-oxidized CNF, the blending ratio of the low molecular weight saccharide to the anion-modified CNF (absolutely dry solid content, 100 parts by mass) is 5 parts by mass in one or a plurality of embodiments. 5 parts by weight to 500 parts by weight, 5 parts by weight to 400 parts by weight, 5 parts by weight to 300 parts by weight or 10 parts by weight to 200 parts by weight, preferably 30 parts by weight to 250 parts by weight or 45 parts by weight. 150 parts by mass.

When the anion-modified CNF is C-modified CNF, the blending ratio of the low molecular weight saccharide to the anion-modified CNF (absolutely dry solid content, 100 parts by mass) is 5 parts by mass or more and 10 parts by mass in one or more embodiments. From 500 parts by weight or from 30 parts by weight to 400 parts by weight, preferably from 50 parts by weight to 350 parts by weight or from 75 parts by weight to 350 parts by weight.

When the anion-modified CNF is phosphate esterified CNF, the blending ratio of the low molecular weight saccharide to the anion-modified CNF (absolutely dry solid content, 100 parts by mass) is 5 parts by mass or more in one or more embodiments, Parts by weight to 500 parts by weight, 5 parts by weight to 400 parts by weight, 5 parts by weight to 300 parts by weight or 10 parts by weight to 200 parts by weight, preferably 30 parts by weight to 250 parts by weight or 45 parts by weight to 150 parts by weight. It is.

In one or a plurality of embodiments, the method for producing dry CNF of the present disclosure includes drying an aqueous suspension containing an anion-modified CNF and a low molecular weight saccharide. In one or more embodiments, the aqueous suspension may be dried by forming a thin film, or may be spray-dried. Thereby, a dry film and / or a dry powder containing an anion-modified CNF and a low molecular weight saccharide can be obtained.

<Low molecular weight polypeptide or amino acid>
In one or a plurality of embodiments, the method for producing dry CNF according to the present disclosure is obtained by mixing an anion-modified CNF and a low molecular weight polypeptide or amino acid to obtain an aqueous suspension of the anion-modified CNF. Drying the aqueous suspension.

In the present disclosure, “low molecular weight polypeptide” refers to a polypeptide having a molecular weight of 10,000 or less. The molecular weight of the low molecular weight polypeptide is 1000 or less, 500 or less, or 150 or more in one or more embodiments. Examples of the amino acid include neutral amino acids such as glycine and glutamine in one or more embodiments.

In one or more embodiments, the method for producing dry CNF according to the present disclosure includes mixing an anion-modified CNF in a wet state (dispersed in water) with a low molecular weight polypeptide or amino acid. Thereby, an aqueous suspension containing anion-modified CNF and a low molecular weight polypeptide or amino acid can be obtained.

The blending ratio of the low molecular weight polypeptide or amino acid to anion-modified CNF (absolutely dry solid content, 100 parts by mass) is 5 parts by mass or more, 5 parts by mass to 500 parts by mass, and 5 parts by mass in one or more embodiments. 400 parts by weight, 5 parts by weight to 300 parts by weight or 10 parts by weight to 200 parts by weight, preferably 30 parts by weight to 350 parts by weight or 30 parts by weight to 150 parts by weight.

In one or a plurality of embodiments, the method for producing dry CNF of the present disclosure includes drying an aqueous suspension containing an anion-modified CNF and a low molecular weight polypeptide or amino acid. In one or more embodiments, the aqueous suspension may be dried by forming a thin film, or may be spray-dried. Thereby, a dry film and / or a dry powder containing an anion-modified CNF and a low molecular weight polypeptide or amino acid can be obtained.

<Low molecular weight PVA>
In one or a plurality of embodiments, the method for producing dry CNF of the present disclosure includes mixing an anion-modified CNF and a low molecular weight PVA to obtain an aqueous suspension of the anion-modified CNF, and the obtained aqueous suspension. Including drying the liquid.

In the present disclosure, “low molecular weight PVA” refers to PVA having a molecular weight of 3000 or less. In one or more embodiments, the molecular weight of the low molecular weight PVA is 2500 or less, 2000 or less, 1500 or less, or 100 or more.

In one or a plurality of embodiments, the method for producing dry CNF according to the present disclosure includes mixing an anion-modified CNF in a wet state (dispersed in water) and a low molecular weight PVA. Thereby, an aqueous suspension containing anion-modified CNF and low molecular weight PVA can be obtained.

The blending ratio of the low molecular weight PVA to the anion-modified CNF (absolute dry solid content, 100 parts by mass) is 5 parts by mass or more, 5 parts by mass to 500 parts by mass, and 5 parts by mass to 400 parts by mass in one or more embodiments. Part by mass, 5 parts by mass to 300 parts by mass or 10 parts by mass to 200 parts by mass, and preferably 30 parts by mass to 350 parts by mass or 30 parts by mass to 150 parts by mass.

In one or a plurality of embodiments, the method for producing dry CNF according to the present disclosure includes drying an aqueous suspension containing an anion-modified CNF and a low molecular weight PVA. In one or more embodiments, the aqueous suspension may be dried by forming a thin film, or may be spray-dried. Thereby, a dry film and / or dry powder containing anion-modified CNF and low molecular weight PVA can be obtained.

In the present disclosure, the drying method of the aqueous suspension is not particularly limited, and in one or a plurality of embodiments, spray drying, air drying, hot air drying, vacuum drying, pressing, and the like can be given.

In one or a plurality of embodiments, dry CNF obtained by the dry CNF production method of the present disclosure is added to 5 g of distilled CNF refined to about 1 mm to 2 mm to 5 g of distilled water, and then for about 1 minute with a point mixer. After stirring, when left standing at room temperature for about 24 hours and then again stirred for about 1 minute with a point mixer, it has a transparent dispersibility at least at the same level or comparable to that of the CNF dispersion before drying.

In one or a plurality of embodiments, the dry CNF obtained by the dry CNF manufacturing method of the present disclosure is obtained by pulverizing a dry CNF in a film shape to about 3 × 3 mm in a 200 mL beaker. When distilled water is added to 7% and then stirred with a three-one motor at 600 rpm and a blade diameter of 3.5 cm for 1 to 3 hours, it is at least as high as the CNF dispersion before drying. Or, it has a transparent dispersibility at a comparable level.

The dry CNF obtained by the dry CNF production method of the present disclosure may be a dry product, and in one or more embodiments, in the form of a film, from the viewpoint of further improving the transparent dispersibility in the dispersion medium to be redispersed. It may be in powder form.

[Dry CNF]
In one aspect, the present disclosure relates to dry CNF comprising a redispersibility improver and an anion-modified CNF (dry CNF of the present disclosure). The dry CNF of this indication can be obtained by the manufacturing method of dry CNF of this indication in one or some embodiment. In one or a plurality of embodiments, the dry CNF of the present disclosure is mainly composed of an anion-modified CNF that is not particularly limited. In one or a plurality of embodiments, the dry CNF of the present disclosure may be in the form of a film or powder.

[Method for producing transparent redispersion of CNF]
In one aspect, the present disclosure relates to a method for producing a transparent redispersion of CNF (a method for producing a transparent redispersion of the present disclosure). In one or a plurality of embodiments, the method for producing a transparent redispersion of the present disclosure includes obtaining an aqueous suspension containing an anion-modified CNF and a redispersibility improving agent, drying the aqueous suspension, And redispersing the obtained dried product in a dispersion medium. In one or a plurality of embodiments, the method for producing a transparent redispersion of CNF according to the present disclosure includes redispersing the dry CNF obtained by the method for producing dry CNF according to the present disclosure in a dispersion medium. According to the method for producing a transparent redispersion of CNF of the present disclosure, in one or a plurality of embodiments, a CNF having a dispersibility comparable to or comparable to an aqueous CNF suspension or an aqueous dispersion that does not undergo a dry state. A transparent redispersion of can be obtained. According to the method for producing a transparent redispersion of CNF of the present disclosure, in one or a plurality of embodiments, a transparent redispersion of dry CNF having high transparency in which dry TEMPO-oxidized CNF is redispersed can be obtained. In one or a plurality of embodiments, the redispersion may be a liquid or a gel.

Examples of the dispersion medium include an aqueous dispersion medium such as water in one or a plurality of embodiments. In one or a plurality of embodiments, the dispersion medium may contain various polymers other than CNF.

The method for producing a transparent redispersion of the present disclosure may further include removing the redispersibility improver from the obtained transparent redispersion. When the redispersibility improver is a cyclodextrin, the removal of the redispersibility improver is performed in one or more embodiments by mixing a linear aliphatic alcohol such as 1-decanol and a transparent redispersion, This can then be done by separating the cyclodextrin from the transparent redispersion by applying physical stress. The addition amount of the linear aliphatic alcohol is not particularly limited, and in one or a plurality of embodiments, it may be a molar equivalent with respect to the cyclodextrin contained in the transparent redispersion. Examples of the physical stress include centrifugation in one or more embodiments.

[Method for Producing CNF Redispersion]
In one aspect, the present disclosure relates to a method for producing a redispersion of CNF (a method for producing a redispersion of the present disclosure). In one or more embodiments, the method for producing a redispersion of the present disclosure includes obtaining an aqueous suspension containing CCM CNF and a redispersibility improving agent, drying the aqueous suspension, and Re-dispersing the obtained dried product in a dispersion medium. In one or a plurality of embodiments, the method for producing a CNF redispersion of the present disclosure includes redispersing the dry CNF obtained by the method for producing a dry CNF of the present disclosure in a dispersion medium. According to the method for producing a CNF redispersion of the present disclosure, in one or a plurality of embodiments, the dispersibility is the same as or comparable to that of a CCM CNF aqueous suspension or aqueous dispersion that is not dried. A re-dispersion of dry CMized CNF can be obtained. In one or a plurality of embodiments, the redispersion may be a liquid or a gel. The method for removing the dispersion medium and the redispersibility improver is the same as the method for producing the transparent redispersion of the present disclosure.

[Method for improving redispersibility of CNF]
As described above, by drying the anion-modified CNF together with the redispersibility improving agent, the redispersibility of the obtained dry CNF, in particular, the transparent dispersibility during redispersion can be improved or improved. Therefore, in another aspect, the present disclosure includes mixing an anion-modified CNF and a redispersibility improver to obtain an aqueous suspension of anion-modified cellulose nanofibers, and drying the aqueous suspension. The present invention relates to a method for improving redispersibility of contained CNF, in particular, transparent dispersibility during redispersion. According to the method for improving redispersibility of the present disclosure, in one or a plurality of embodiments, the transparent dispersibility at the time of redispersion of a dried product of TEMPO-oxidized CNF among anion-modified CNFs can be further improved or improved. Moreover, according to the redispersibility improving method of the present disclosure, in one or a plurality of embodiments, dispersibility during redispersion of a dry product of C-modified CNF among anion-modified CNFs can be further improved or improved.
According to the redispersibility improving method of the present disclosure, in one or a plurality of embodiments, it is possible to further improve or improve the transparent dispersibility during redispersion of the dried product of phosphate esterified CNF among anion-modified CNFs. . The redispersibility improving agent and the blending ratio are the same as in the method for producing dry CNF of the present disclosure.

In one or a plurality of embodiments, the aqueous suspension may contain a third component other than the anion-modified CNF and the redispersibility improving agent during redispersion. Examples of the third component include a water-soluble polymer in one or a plurality of embodiments.

In one or a plurality of embodiments, the aqueous suspension can be dried in the same manner as the dry CNF production method of the present disclosure.

[Redispersibility improver]
In another aspect, the present disclosure provides a redispersibility improving agent for improving or improving redispersibility of dry cellulose nanofibers in an aqueous dispersion medium, in particular, transparent dispersibility during redispersion (redispersion of the present disclosure). Property improver). The redispersibility improving agent of the present disclosure includes one or more selected from the group consisting of low molecular weight saccharides, low molecular weight polypeptides, amino acids, and low molecular weight PVC. The redispersibility improver of the present disclosure is used in one or a plurality of embodiments in the production of dry cellulose nanofibers having improved or improved redispersibility in a dispersion medium, in particular, transparent dispersibility during redispersion. can do. Low molecular weight saccharides, low molecular weight polypeptides, amino acids, and low molecular weight PVC are as described above.

[Dry composition]
In one aspect, the present disclosure is a dry composition containing anion-modified cellulose nanofibers and a redispersibility improver, wherein the redispersibility improver is a saccharide having a molecular weight of 50,000 or less, a low molecular weight polypeptide, The present invention relates to a dry composition (dry composition of the present disclosure) comprising at least one selected from the group consisting of amino acids and low molecular weight PVC.

In one or a plurality of embodiments, the proportion of the redispersibility improver in the dry composition of the present disclosure is 5% by mass or more and 5% by mass to 500% by mass with respect to the anion-modified CNF (absolutely dry solid content). 5% by mass to 400% by mass, 5% by mass to 300% by mass, 10% by mass to 200% by mass, or 20% by mass to 300% by mass, and preferably 30% by mass to 350% by mass or 30% by mass to 150% by mass.

When the anion-modified CNF is TEMPO-oxidized CNF, the proportion of the redispersibility improver in the dry composition of the present disclosure is, in one or more embodiments, 5 masses relative to TEMPO-oxidized CNF (absolutely dry solids). % Or more, 5 mass% to 500 mass%, 5 mass% to 400 mass%, 5 mass% to 300 mass%, or 10 mass% to 200 mass%, preferably 30 mass% to 250 mass% or 45 mass%. ~ 150% by weight.

When the anion-modified CNF is C-merized CNF, the proportion of the redispersibility improver in the dry composition of the present disclosure is, in one or more embodiments, 5 masses with respect to TEMPO oxidized CNF (absolutely dry solids). % Or more, 10 mass% to 500 mass%, or 30 mass% to 400 mass%, preferably 50 mass% to 350 mass%, or 75 mass% to 350 mass%.

When the anion-modified CNF is phosphate esterified CNF, the proportion of the redispersibility improver in the dry composition of the present disclosure is, in one or more embodiments, based on phosphate esterified CNF (absolutely dry solids). 5 mass% or more, 5 mass% to 500 mass%, 5 mass% to 400 mass%, 5 mass% to 300 mass%, or 10 mass% to 200 mass%, preferably 30 mass% to 250 mass%. Or 45 mass% to 150 mass%.

In one or a plurality of embodiments, the dry composition of the present disclosure may include a third component other than the anion-modified CNF and the redispersibility improving agent. Examples of the third component include a water-soluble polymer in one or a plurality of embodiments.

In one or more embodiments, the dry composition of the present disclosure may be a film, a solid, or a powder. The film thickness of the dry composition of this indication is 50 micrometers or more or 100 micrometers or more, or 1000 micrometers or less or 300 micrometers or less in one or some embodiment.

In one or a plurality of embodiments, the dry composition of the present disclosure may be produced by mixing an anion-modified CNF and a redispersibility improver, and, if necessary, the third component and drying it. Alternatively, the dry CNF of the present disclosure and the third component may be mixed and dried.

The present disclosure further relates to one or more of the following embodiments.
[1] An anion-modified CNF and a redispersibility improver are mixed to obtain an aqueous suspension of the anion-modified CNF, and the aqueous suspension is dried to obtain a dry CNF.
The method for producing dry CNF, wherein the redispersibility improving agent is selected from the group consisting of sugars having a molecular weight of 50,000 or less, low molecular weight polypeptides, amino acids, and low molecular weight polyvinyl alcohol.
[2] The method for producing dry CNF according to [1], wherein the redispersibility improving agent is carboxymethylcellulose having a molecular weight of 20,000 or less.
[3] Production of dry CNF, comprising mixing anion-modified CNF and a low molecular weight saccharide to obtain an aqueous suspension of anion-modified CNF, and drying the aqueous suspension to obtain dry CNF Method.
[4] The method for producing dry CNF according to [3], wherein the saccharide has a molecular weight of 50,000 or less.
[5] Production of dry CNF, comprising mixing anion-modified CNF and low molecular weight CMC to obtain an aqueous suspension of anion-modified CNF, and drying the aqueous suspension to obtain dry CNF Method.
[6] The method for producing dry CNF according to [5], wherein the molecular weight of the CMC is 20,000 or less.
[7] Mixing an anion-modified CNF with at least one of a low molecular weight polypeptide and an amino acid to obtain an aqueous suspension of the anion-modified CNF, and drying the aqueous suspension to obtain a dry CNF A method for producing dry CNF.
[8] Production of dry CNF, comprising mixing anion-modified CNF and low molecular weight PVA to obtain an aqueous suspension of anion-modified CNF, and drying the aqueous suspension to obtain dry CNF Method.
[9] The method for producing dry CNF according to any one of [1] to [8], wherein the anion-modified CNF is carboxylated CNF, C-converted CNF, or phosphate-esterified CNF.
[10] comprising mixing an anion-modified CNF and a redispersibility improver to obtain an aqueous suspension of the anion-modified CNF, and drying the aqueous suspension;
The method for improving redispersibility of CNF, wherein the redispersibility improving agent is selected from the group consisting of sugars having a molecular weight of 50,000 or less, low molecular weight polypeptides, amino acids, and low molecular weight polyvinyl alcohol.
[11] A method for improving the redispersibility of CNF, comprising mixing an anion-modified CNF and a low molecular weight saccharide to obtain an aqueous suspension of the anion-modified CNF, and drying the aqueous suspension.
[12] A method for improving the redispersibility of CNF, comprising mixing an anion-modified CNF and a low molecular weight CMC to obtain an aqueous suspension of the anion-modified CNF, and drying the aqueous suspension.
[13] Redispersion of CNF, comprising mixing an anion-modified CNF with at least one of a low molecular weight polypeptide and an amino acid to obtain an aqueous suspension of the anion-modified CNF, and drying the aqueous suspension Improvement method.
[14] A method for improving the redispersibility of CNF, comprising mixing an anion-modified CNF and a low molecular weight PVA to obtain an aqueous suspension of the anion-modified CNF, and drying the aqueous suspension.
[15] The method for improving redispersibility of CNF according to any one of [10] to [14], wherein the anion-modified CNF is carboxylated CNF, CCM CNF, or phosphate ester CNF.
[16] A drug for improving or improving the redispersibility of dry CNF in an aqueous dispersion medium, selected from the group consisting of low molecular weight saccharides, low molecular weight polypeptides, amino acids, and low molecular weight polyvinyl alcohol A redispersibility improving agent containing one or more of the above.
[17] A redispersibility improving agent for improving or improving the redispersibility of dry CNF in an aqueous dispersion medium, comprising a low molecular weight CMC.
[18] A redispersibility improver for use in the production of dry CNF, comprising at least one selected from the group consisting of low molecular weight sugars, low molecular weight polypeptides, amino acids, and low molecular weight polyvinyl alcohol. Redispersibility improving agent containing.
[19] A redispersibility improving agent for use in the production of dry CNF, comprising a low molecular weight CMC.
[20] A redispersibility improver for use in the method for producing dry CNF according to any one of [1] to [9] or the redispersibility improving method according to any one of [10] to [15] A redispersibility improving agent comprising at least one selected from the group consisting of a low molecular weight saccharide, a low molecular weight polypeptide, an amino acid, and a low molecular weight polyvinyl alcohol.
[21] A redispersibility improver for use in the method for producing dry CNF according to any one of [1] to [9] or the redispersibility improving method according to any one of [10] to [15] A redispersibility improver comprising low molecular weight CMC.
[22] A dry composition comprising an anion-modified CNF and a redispersibility improver,
A composition comprising the redispersibility improving agent comprising at least one selected from the group consisting of sugars having a molecular weight of 50,000 or less, low molecular weight polypeptides, amino acids, and low molecular weight polyvinyl alcohol.
[23] The composition according to [22], wherein the anion-modified CNF is carboxylated CNF, CCM CNF, or phosphate ester CNF.

Hereinafter, the present disclosure will be further described using examples and comparative examples. However, the present disclosure is not construed as being limited to the following examples.

[Production of carboxylated cellulose nanofiber (anion-modified CNF1)]
Bleached unbeaten kraft pulp derived from conifers (whiteness 85%) 5.00 g (absolutely dried), TEMPO (Sigma Aldrich) 39 mg (0.05 mmol for 1 g of absolutely dried cellulose) and 514 mg of sodium bromide (absolutely dry) The solution was added to 500 ml of an aqueous solution in which 1.0 mmol) was dissolved in 1 g of dry cellulose, and stirred until the pulp was uniformly dispersed. An aqueous sodium hypochlorite solution was added to the reaction system so that sodium hypochlorite was 5.5 mmol / g, and the oxidation reaction was started at room temperature. During the reaction, the pH in the system was lowered, but a 3M sodium hydroxide aqueous solution was sequentially added to adjust the pH to 10. The reaction was terminated when sodium hypochlorite was consumed and the pH in the system no longer changed.
The reaction mixture was filtered through a glass filter to separate the pulp, and the pulp was sufficiently washed with water to obtain oxidized pulp (carboxylated cellulose). The pulp yield at this time was 90%, the time required for the oxidation reaction was 90 minutes, and the amount of carboxyl groups was 1.6 mmol / g. This was adjusted to a pulp solid content of 1.1% (w / v) with water, treated three times with an ultra-high pressure homogenizer (20 ° C., 150 Mpa), and carboxylated cellulose nanofiber (hereinafter referred to as T-CNF). An aqueous dispersion was obtained. The average fiber diameter was 3 nm and the aspect ratio was 250.

[Production of Carboxymethylated Cellulose Nanofiber (Anion-Modified CNF2)]
In a stirrer capable of mixing pulp, 200 g dry needle bleached kraft pulp (manufactured by Nippon Paper Industries Co., Ltd.) and 111 g sodium hydroxide dry mass (2.25 times mol per anhydroglucose residue of the bottoming material) In addition, water was added so that the pulp solid content was 20% (w / v). Thereafter, after stirring at 30 ° C. for 30 minutes, 216 g of sodium monochloroacetate (in terms of active ingredient, 1.5 times mol per glucose residue of pulp) was added. After stirring for 30 minutes, the temperature was raised to 70 ° C. and stirred for 1 hour. Thereafter, the reaction product was taken out, neutralized and washed to obtain a carboxymethylated pulp having a carboxymethyl substitution degree of 0.25 per glucose unit. The pulp solid content is 1.2% (w / v) with water, and the fiber is fibrillated by treating with a high-pressure homogenizer five times at 20 ° C. and a pressure of 150 MPa. The carboxymethylated cellulose nanofiber (hereinafter referred to as CM-CNF) ) The average fiber diameter was 12 nm and the aspect ratio was 130.

[Production of Phosphate Ester Cellulose Nanofiber (Anion-Modified CNF3)]
6.75 g of sodium dihydrogen phosphate dihydrate and 4.83 g of disodium hydrogen phosphate are dissolved in 19.62 g of water to obtain an aqueous solution of a phosphoric acid compound (hereinafter referred to as “phosphorylation reagent”). It was. Water is added to unbleached kraft pulp (NUKP, moisture 80%, Canadian standard freeness (CSF) 580 ml measured according to JIS P8121) so that the pulp solid content is 4% (w / v). It was. After that, using a double disc refiner, it was beaten until an irregular CSF (plain mesh 80 mesh, according to JIS P8121 except that the amount of pulp collected was 0.3 g) was 200 ml, and the length average fiber length was 0.66 mm. The cellulose suspension thus obtained was diluted to a pulp solid content of 0.3% (w / v), and a pulp sheet (thickness 200 μm) having a moisture content of 90% and a solid content (absolute dry mass) of 3 g was obtained by a papermaking method. It was. This pulp sheet was immersed in 31.2 g of the phosphorylating reagent (80 parts by mass as the amount of phosphorus element with respect to 100 parts by mass of the dried pulp), and heated for 1 hour with an air dryer at 105 ° C. (Yamato Scientific Co., Ltd. DKM400) Further, heat treatment was performed at 150 ° C. for 1 hour to introduce phosphate groups into the cellulose fibers. Subsequently, 500 ml of ion-exchanged water was added to the pulp sheet in which the phosphate group was introduced into the cellulose fiber, and the mixture was dehydrated after washing with stirring. The dehydrated sheet was diluted with 300 ml of ion-exchanged water, and 5 ml of 1N aqueous sodium hydroxide solution was added little by little with stirring to obtain a cellulose suspension having a pH of 12 to 13. Thereafter, the cellulose suspension was dehydrated and washed by adding 500 ml of ion exchange water. This dehydration washing was repeated two more times. Ion exchange water was added to the sheet obtained after washing and dehydration, and the mixture was stirred to obtain a 0.5 mass% cellulose suspension. This cellulose suspension was defibrated for 30 minutes using a defibrating apparatus (Cleamix-2.2S, manufactured by M Technique Co., Ltd.) at 21500 rpm, and defibrated cellulose (phosphate ester) Cellulose nanofiber) suspension was obtained. When the cellulose contained in the defibrated cellulose suspension was observed with a transmission electron microscope, it was confirmed that fine fibrous cellulose having a width of 4 nm was contained. Moreover, it was confirmed by X-ray diffraction that the cellulose maintained the cellulose I type crystal. Further, the infrared absorption spectrum was measured by FT-IR. Absorption based on phosphate groups was observed at 1230 cm ⁻¹ to 1290 cm ⁻¹ , confirming the addition of phosphate groups. The amount of phosphate group introduced at this time was 2.1 mmol / g per 1 g (mass) of fine fibrous cellulose.

(Experimental example 1)
Using the chemicals shown in Table 1, production of dry anion-modified CNF (dry CNF) and redispersibility of dry CNF were evaluated. As the anion-modified CNF, anion-modified CNF1 (T-CNF, average fiber width: 3 nm, aspect ratio: 250) was used.

[Production of dry CNF]
The chemical | medical agent shown in Table 1 was added with powder to 1% (w / v) pulp solid content suspension of anion-modified CNF1. The chemical | medical agent was added so that it might become the quantity (mass part) of Table 1 with respect to 100 mass parts of CNFs. The chemicals used in the examples in Table 1 were both water-soluble because they were dissolved in a clear or cloudy state when mixed with 25 ° C. water at a concentration of 1% or 5%.
The drug was added in an amount equivalent to the CNF solid content in the suspension. Next, the mixture was stirred and mixed with a stirrer, a point mixer, a homomixer, or the like until it became transparent. The obtained liquid was applied on a Teflon (trademark) plate or a Teflon (trademark) dish, and dried with hot air of 60 ° C. to 105 ° C. to obtain a film-like dry CNF.
The blank was the same as above except that no drug was added.

[Redispersion of dry CNF]
The film-like dry CNF was refined by hand to about 1 mm to 2 mm, and 0.1 g was weighed into a test tube. Distilled water (5 g) was added, the mixture was stirred for about 1 minute with a point mixer, and then allowed to stand at room temperature for about 24 hours. This was again stirred with a point mixer for about 1 minute to obtain an aqueous dispersion or aqueous suspension in which anion-modified CNF was redispersed (solid content concentration 2% (w / v)).

[Evaluation of redispersibility]
The redispersibility of the aqueous redispersion liquid or aqueous suspension in the test tube was evaluated visually. Evaluation was performed based on the following evaluation criteria. The results are shown in Table 1 below.
<Evaluation criteria>
A: Undispersed CNF pieces are not completely observed, and show high transparency equivalent to anion-modified CNF before drying.
B: Although a trace amount of fine undispersed CNF pieces is observed, it shows high transparency.
C: A small amount of undispersed CNF pieces is observed. D: Dispersion of CNF is not recognized at all, and it is cloudy.

As shown in Table 1, none of the comparative examples dried with a substance having a strong anionic property, a cationic polymer or a water-insoluble substance could disperse the obtained dry CNF. On the other hand, in the examples dried with low molecular weight saccharides or PVA or amino acids, it was confirmed that the obtained dry CNF can be dispersed, and redispersibility, particularly, transparent dispersibility during redispersion is improved. did it.
Moreover, in the blank and the comparative example, a white precipitate and a suspended | floating matter were confirmed and it became cloudy. On the other hand, in all the test tubes of the examples, almost no precipitates or undispersed gel-like substances were confirmed, and the test tubes were transparent. In particular, in the test tube with an evaluation of redispersibility of A, no precipitate or undispersed gel was confirmed, and the transparency was particularly high.

[Evaluation of refilming and gelation]
The aqueous dispersion evaluated as A or B in the evaluation of redispersibility in Table 1 was evaluated for refilming and gelation.
Re-filming was performed by weighing about 2 g of an aqueous dispersion (re-dispersion on a Teflon (trademark) plate) and thoroughly drying with hot air of 70 ° C. to 80 ° C. This was done by adding a few drops of a 20% calcium chloride solution in a test tube containing.
As a result, both formed a film and a gel. That is, it was suggested that the physical properties of dry CNF obtained by the production method of the present disclosure are not significantly different from those of untreated (before drying treatment) anion-modified CNF.

(Experimental example 2)
Using CMC (manufactured by Nippon Paper Industries Co., Ltd.) shown in Table 2 below, the redispersibility of anion-modified CNF was evaluated. As the anion-modified CNF, anion-modified CNF1 (T-CNF, average fiber diameter: 3 nm, aspect ratio: 250) was used. “Sunrose” is a registered trademark of Nippon Paper Industries Co., Ltd.

[Production and redispersion of dry CNF]
A film-like dry CNF was obtained in the same procedure as in Experimental Example 1, except that the CMC shown in Table 2 below was used instead of the drugs in Table 1. Film-like dry CNF is pulverized to about 3 x 3 mm, adjusted in distilled water to a solid content of 0.7% (w / v) in a 200 mL beaker, and a stirrer with a three-one motor of 600 rpm and a blade diameter of 3.5 cm The mixture was stirred for 1 to 3 hours to obtain an aqueous redispersion or aqueous suspension.
The blank was the same as above except that no drug was added.

[Evaluation of redispersibility]
During stirring for 1 to 3 hours, the dispersion state of CNF in the aqueous redispersion or suspension was observed every hour, and the redispersibility was evaluated based on the following evaluation criteria. The results are shown in Table 2 below.
<Evaluation criteria>
A: Undispersed CNF pieces are not completely observed B: Fine undispersed CNF pieces are observed in a very small amount C: Undispersed CNF pieces are observed in a small amount D: No dispersion of CNF is observed

As shown in Table 2, the redispersibility of dry CNF could be improved by using CMC having a molecular weight of 20,000 or less. In particular, in the test tube of the example in which CMC having a molecular weight of 20,000 or less was added and the stirring time was 2 hours or more, no precipitate or undispersed gel was confirmed, and anion-modified CNF dispersion before drying was confirmed. A highly transparent CNF redispersion liquid equivalent to the liquid could be obtained.
It was also confirmed that the time required for redispersion of dry CNF could be shortened by using CMC having a molecular weight of 20,000 or less.

(Experimental example 3)
Using the agents shown in Table 3, anion-modified CNF2 (CM-CNF, average fiber width: 12 nm, aspect ratio: 130 or more) was used as the anion-modified CNF, and the temperature of the hot air during the production of the dried film was 60 ° C. Except that, dry CNF was produced and dry CNF was redispersed in the same manner as in Experimental Example 1 to obtain an aqueous dispersion or suspension in which dry CM CNF was redispersed.

[Evaluation of redispersibility]
The redispersibility of the aqueous redispersion liquid or aqueous suspension in the test tube was evaluated visually. Evaluation was performed based on the following evaluation criteria. The results are shown in Table 3 below.
<Evaluation criteria>
A: Undispersed CNF pieces are not completely observed B: Fine undispersed CNF pieces are observed in a small amount C: Undispersed CNF pieces are observed in a small amount D: No dispersion of CNF is observed

As shown in Table 3, by drying together with low molecular weight sugars such as dextrin and α-cyclodextrin, the obtained dried CNF could be dispersed in distilled water for C-converted CNF.
Moreover, it has confirmed that the redispersibility was improved compared with the conventional chemical | medical agent currently used for the improvement of the redispersibility of dry CNF.

Claims

Mixing an anion-modified cellulose nanofiber and a redispersibility improver to obtain an aqueous suspension of the anion-modified cellulose nanofiber, and drying the aqueous suspension to obtain a dry cellulose nanofiber,
The method for producing dry cellulose nanofibers, wherein the redispersibility improving agent is selected from the group consisting of saccharides having a molecular weight of 50,000 or less, low molecular weight polypeptides, amino acids, and low molecular weight polyvinyl alcohol.
The production method according to claim 1, wherein the redispersibility improving agent is carboxymethylcellulose having a molecular weight of 20,000 or less.
The method for producing dry cellulose nanofibers according to claim 1 or 2, wherein the anion-modified cellulose nanofibers are carboxylated cellulose nanofibers, carboxymethylated cellulose nanofibers, or phosphate esterified cellulose nanofibers.
Mixing an anion-modified cellulose nanofiber and a redispersibility improver to obtain an aqueous suspension of the anion-modified cellulose nanofiber, and drying the aqueous suspension,
The method for improving redispersibility of cellulose nanofibers, wherein the redispersibility improving agent is selected from the group consisting of sugars having a molecular weight of 50,000 or less, low molecular weight polypeptides, amino acids, and low molecular weight polyvinyl alcohol.
The method for improving redispersibility according to claim 4, wherein the anion-modified cellulose nanofiber is a carboxylated cellulose nanofiber, a carboxymethylated cellulose nanofiber or a phosphate esterified cellulose nanofiber.
A drug for improving or improving the redispersibility of dry cellulose nanofibers in a dispersion medium, comprising a saccharide having a molecular weight of 50,000 or less, a low molecular weight polypeptide, an amino acid, and a low molecular weight polyvinyl alcohol A redispersibility improving agent containing one or more selected.
A dry composition comprising an anion-modified cellulose nanofiber and a redispersibility improver,
A composition comprising the redispersibility improving agent comprising at least one selected from the group consisting of sugars having a molecular weight of 50,000 or less, low molecular weight polypeptides, amino acids, and low molecular weight polyvinyl alcohol.
The composition according to claim 7, wherein the anion-modified cellulose nanofiber is a carboxylated cellulose nanofiber, a carboxymethylated cellulose nanofiber or a phosphate esterified cellulose nanofiber.