Resin composition and molded article thereof

Abstract

A resin composition containing chemically modified nanocellulose, a sugar having an ionic group, and a water-soluble resin.

Description

Resin composition and molded article thereof

[0001] The present invention relates to a resin composition and a molded article thereof.

[0002] In recent years, research has been conducted into the use of plant fibers as a reinforcing material for resins. Plant fibers are not artificially synthesized, but are instead derived from plants and broken down. Since plant fibers leave almost no ash behind when burned, there are no problems with ash disposal in incinerators or landfill disposal. For this reason, research into using plant fibers as a reinforcing material for resins has been conducted in recent years, and in particular the use of nanocellulose, which is plant fiber broken down to the nano level, has been studied.

[0003] For example, Patent Document 1 describes a resin composition containing nanocellulose and a polymer of an ethylenically unsaturated monomer, wherein the nanocellulose contains an oxide of a cellulose-based raw material with hypochlorous acid or a salt thereof, is substantially free of N-oxyl compounds, and satisfies the following (I) and / or (II): (I) the zeta potential is -30 mV or less; (II) the light transmittance in a mixed solution obtained by mixing nanocellulose with water to a solids concentration of 0.1% by mass is 95% or more. The resin composition of Patent Document 1 can increase the strength of the resin.

[0004] In addition, Patent Document 2 describes a polyvinyl alcohol film, which comprises polyvinyl alcohol (A), crystalline cellulose (B) and water-soluble cellulose derivative (C), and the content of crystalline cellulose (B) is 0.1 parts by mass or more and 20 parts by mass or less relative to 100 parts by mass of polyvinyl alcohol (A), and the content of water-soluble cellulose derivative (C) is 0.01 parts by mass or more relative to 100 parts by mass of polyvinyl alcohol (A).The polyvinyl alcohol film of Patent Document 2 is said to have a large stretching stress in a stretching bath and high transparency.

[0005] International Publication No. 2022 / 059705 Japanese Patent Application Laid-Open No. 2021-91818

[0006] The present invention provides a resin composition that can be molded into a molded article having an improved storage modulus.

[0007] The present inventors have discovered that by combining chemically modified nanocellulose with a sugar having an ionic group, it is possible to provide a resin composition that can be used to mold a molded article with an improved storage modulus.

[0008] The present invention includes the following embodiments. [1] A resin composition comprising: chemically modified nanocellulose; a saccharide having an ionic group; and a water-soluble resin. [2] The resin composition according to [1], wherein the crystallinity of the chemically modified nanocellulose is 10 to 70%. [2-1] The resin composition according to [1] or [2], wherein the crystallinity of the chemically modified nanocellulose is 20 to 70%. [2-2] The resin composition according to any one of [1] to [2-1], wherein the crystallinity of the chemically modified nanocellulose is 30 to 65%. [2-3] The resin composition according to any one of [1] to [2-2], wherein the crystallinity of the chemically modified nanocellulose is 40 to 60%. [2-4] The resin composition according to any one of [1] to [2-3], wherein the crystallinity of the chemically modified nanocellulose is 50 to 55%. [3] The resin composition according to any one of [1] to [2-4], wherein the average fiber length of the chemically modified nanocellulose is 50 to 3,000 nm. [3-1] The resin composition according to any one of [1] to [3], wherein the average fiber length of the chemically modified nanocellulose is 50 to 700 nm. [3-2] The resin composition according to any one of [1] to [3-1], wherein the average fiber length of the chemically modified nanocellulose is 50 to 500 nm. [3-3] The resin composition according to any one of [1] to [3-2], wherein the average fiber length of the chemically modified nanocellulose is 60 to 300 nm. [3-4] The resin composition according to any one of [1] to [3-3], wherein the average fiber length of the chemically modified nanocellulose is 70 to 200 nm. [4] The resin composition according to any one of [1] to [3-4], wherein the average fiber width of the chemically modified nanocellulose is 1 to 20 nm. [4-1] The resin composition according to any one of [1] to [4], wherein the average fiber width of the chemically modified nanocellulose is 1 to 15 nm. [4-2] The resin composition according to any one of [1] to [4-1], wherein the average fiber width of the chemically modified nanocellulose is 1 to 10 nm. [4-3] The resin composition according to any one of [1] to [4-2], wherein the average fiber width of the chemically modified nanocellulose is 1 to 5 nm. [5] The resin composition according to any one of [1] to [4-3], wherein the aspect ratio of the chemically modified nanocellulose is 20 to 1000.[5-1] The resin composition according to any one of [1] to [5], wherein the aspect ratio of the chemically modified nanocellulose is 20 to 200. [5-2] The resin composition according to any one of [1] to [5-1], wherein the aspect ratio of the chemically modified nanocellulose is 30 to 190. [5-3] The resin composition according to any one of [1] to [5-2], wherein the aspect ratio of the chemically modified nanocellulose is 40 to 180. [6] The resin composition according to any one of [1] to [5-3], wherein the chemically modified nanocellulose has a carboxy group. [7] The resin composition according to any one of [1] to [6], wherein the chemically modified nanocellulose is oxidized nanocellulose. [8] The resin composition according to any one of [1] to [7], wherein the chemically modified nanocellulose comprises an oxide of a cellulose-based raw material with hypochlorous acid or a salt thereof, and is substantially free of N-oxyl compounds. [9] The resin composition according to any one of [1] to [9], wherein the chemically modified nanocellulose has a structure in which the hydroxyl groups at the second and third positions of the glucopyranose ring are oxidized to introduce dicarboxy groups.

[10] The resin composition according to any one of [1] to [9], wherein the ionic group of the saccharide contains a carboxy group and / or a sulfate group.

[11] A molded product of the resin composition according to any one of [1] to

[10] .

[12] The molded product according to

[11] , wherein the molded product is a film.

[13] An adhesive comprising the resin composition according to any one of [1] to

[10] .

[0009] The present invention can provide a resin composition that can be used to form a molded article having an improved storage modulus.

[0010] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these and various modifications are possible without departing from the gist of the present invention.

[0011] <Resin Composition> One embodiment of the present invention relates to a resin composition containing chemically modified nanocellulose, a saccharide having an ionic group, and a water-soluble resin.

[0012] The resin composition according to this embodiment can be used in combination with chemically modified nanocellulose and sugars having ionic groups to form a molded article with an improved storage modulus. The reason why a molded article with an improved storage modulus can be formed is presumed to be that the presence of sugars having ionic groups improves the dispersibility of chemically modified nanocellulose in water-soluble resins, but the present invention is not limited by this reason.

[0013] [Chemically Modified Nanocellulose] The resin composition according to this embodiment contains chemically modified nanocellulose.

[0014] "Chemically modified nanocellulose" in this specification refers to cellulose that has been chemically modified and nanosized. Chemically modified nanocellulose can be obtained, for example, by chemically modifying and nanoizing a cellulosic raw material. The order of chemical modification and nanoization is not particularly limited, but it is preferable to chemically modify the cellulosic raw material and then nanoize it. Nanoization tends to be easier when the cellulosic raw material is chemically modified first.

[0015] The amount of chemically modified nanocellulose is preferably 0.1 to 40% by mass, more preferably 1 to 30% by mass, and even more preferably 5 to 15% by mass, based on the mass of the water-soluble resin.

[0016] The amount of chemically modified nanocellulose is preferably 10 to 10,000% by mass, more preferably 50 to 5,000% by mass, based on the mass of the saccharide having an ionic group. It is still more preferably 80 to 2,000% by mass, and particularly preferably 100 to 500% by mass.

[0017] As used herein, "chemical modification" refers to chemically changing a part of the cellulose structure. Examples of chemical modifications include oxidation modification, phosphorylation modification, and carboxymethylation modification.

[0018] In the oxidative modification, for example, a cellulose-based raw material is oxidized to introduce a carboxyl group into at least a part of the cellulose structure.

[0019] In phosphorylation modification, for example, a compound or a salt thereof containing a phosphate group on at least some of the hydroxyl groups of the glucose units constituting cellulose undergoes a dehydration reaction to form a phosphate ester, thereby introducing a phosphate group or a salt thereof.

[0020] In the carboxymethylation modification, for example, carboxymethyl groups are introduced by ether-bonding to at least some of the hydroxyl groups of the glucose units that constitute cellulose.

[0021] Although not particularly limited, the chemical modification is preferably oxidative modification, i.e., the chemically modified nanocellulose is preferably oxidized nanocellulose.

[0022] The oxidative modification can be carried out by reacting the cellulosic raw material with an oxidizing agent. Examples of the oxidizing agent include hypochlorous acid or its salts and N-oxyl compounds. Examples of the N-oxyl compounds include 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO).

[0023] From the viewpoint of forming a molded body with a superior storage modulus, it is preferable to use hypochlorous acid or a salt thereof as the oxidizing agent. That is, it is preferable that the chemically modified nanocellulose is obtained by oxidizing a cellulosic raw material with hypochlorous acid or a salt thereof (without using an N-oxyl compound) and nano-sizing the resulting oxidized cellulose.

[0024] The inventors have surprisingly found that when oxidized nanocellulose obtained using hypochlorous acid or its salts (without using an N-oxyl compound) is used in combination with a sugar having an ionic group, the storage modulus of the resulting molded article is significantly improved compared to when nanocellulose obtained by other methods (e.g., TEMPO oxidation or mechanical defibration) is used.

[0025] The following description focuses on oxidation of cellulosic raw materials with hypochlorous acid or its salts, but chemically modified nanocellulose is not limited to nanocellulose oxidized with hypochlorous acid or its salts.

[0026] [Oxidized Cellulose] Hereinafter, unless otherwise specified, "oxidized cellulose" refers to an oxide of a cellulosic raw material with hypochlorous acid or a salt thereof before defibration.

[0027] Examples of hypochlorous acid or salts thereof include hypochlorous acid water, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, and ammonium hypochlorite.

[0028] Although the amount of hypochlorous acid or its salt to be used is not particularly limited, it is preferable to use it so that the effective chlorine concentration in the reaction system is 6 to 43 mass%. The effective chlorine concentration may be a low concentration of 6 to 14 mass% or a high concentration of 14 to 43 mass%.

[0029] The definition of the effective chlorine concentration of hypochlorous acid or a salt thereof is as described in WO 2022 / 009979.

[0030] The cellulosic raw material is not particularly limited as long as it is a material primarily composed of cellulose, and examples thereof include pulp, natural cellulose, and fine cellulose obtained by depolymerizing cellulose through mechanical processing. The cellulosic raw material preferably has a type I crystal structure. Commercially available cellulose-based raw materials, such as crystalline cellulose derived from pulp, can be used as is. Alternatively, unused biomass containing a large amount of cellulose, such as soybean hulls or soybean pulp, may also be used as the raw material. Furthermore, the cellulosic raw material may be pre-treated with an appropriate concentration of alkali to facilitate the penetration of the oxidizing agent into the raw pulp. Cellulose is the main component of plants, and bundles of cellulose molecules are called cellulose microfibrils. The cellulose in the cellulosic raw material is also present in the form of cellulose microfibrils.

[0031] (N-oxyl compounds) Oxidized cellulose is preferably substantially free of N-oxyl compounds. By being substantially free of N-oxyl compounds, the impact on the environment and human body is sufficiently reduced, resulting in a high level of safety. Examples of N-oxyl compounds include 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO).

[0032] As used herein, "substantially free of N-oxyl compounds" means that no N-oxyl compounds are used in producing the oxidized cellulose, that the oxidized cellulose contains no N-oxyl compounds, or that the content of N-oxyl compounds is 2.0 ppm by mass or less, preferably 1.0 ppm by mass or less, relative to the total amount of oxidized cellulose. Furthermore, when the content of N-oxyl compounds, as an increase from the cellulosic raw material, is preferably 2.0 ppm by mass or less, more preferably 1.0 ppm by mass or less, it is also considered to be "substantially free of N-oxyl compounds."

[0033] The content of N-oxyl compounds can be measured by known means, such as a method using a trace total nitrogen analyzer (for example, TN-2100H manufactured by Nitto Seiko Analytech Co., Ltd.).

[0034] (Carboxy group amount) The carboxy group amount of oxidized cellulose is preferably 0.1 to 3.0 mmol / g, more preferably 0.2 to 2.0 mmol / g, even more preferably 0.3 to 1.5 mmol / g, particularly preferably 0.4 to 1.2 mmol / g, and most preferably 0.5 to 0.9 mmol / g.

[0035] The amount of carboxy groups in oxidized cellulose can be measured by the method described in WO 2022 / 009979.

[0036] The oxidized cellulose in this embodiment preferably has a structure in which at least two of the hydroxyl groups on the glucopyranose ring that constitutes the cellulose are oxidized, and more specifically, preferably has a structure in which the hydroxyl groups at the second and third positions on the glucopyranose ring are oxidized and dicarboxyl groups are introduced. Furthermore, it is preferable that the hydroxyl group at the sixth position on the glucopyranose ring is not oxidized and remains as a hydroxyl group. The position of the carboxyl group on the glucopyranose ring is determined by the solid １３ It can be analyzed by C-NMR spectrum.

[0037] Rayon has the same chemical structure as cellulose, and its oxide (rayon oxide) is water-soluble. １３ By performing C-NMR measurement, a carbon peak attributable to a carboxy group is observed at 165 to 185 ppm. In one embodiment of the oxidation of a cellulosic raw material with hypochlorous acid or its salt, two signals appear in this chemical shift range. Furthermore, by solution two-dimensional NMR measurement, it can be determined that the carboxy groups are introduced at the 2- and 3-positions.

[0038] Solid oxide of cellulosic raw materials with hypochlorous acid or its salts １３ In C-NMR, when the amount of carboxyl groups introduced is large, two signals appear at 165 to 185 ppm, and when the amount of carboxyl groups introduced is small, a very broad signal may appear. As can be seen from the results for oxidized rayon, the signals of the carboxyl group carbons introduced at the 2nd and 3rd positions are close to each other, and the signals are not clearly visible in solid state analysis with low resolution. １３ In C-NMR, the separation of the two signals is insufficient. Therefore, when the amount of carboxyl group introduced is small, a broad signal is observed. １３ In the C-NMR spectrum, the introduction of carboxy groups at the 2- and 3-positions can be confirmed by evaluating the broadening of the peak appearing at 165 to 185 ppm.

[0039] That is, solid １３A baseline is drawn around the peak in the range of 165 ppm to 185 ppm in a C-NMR spectrum to determine the overall area value, and then the area value is vertically divided at the peak top to determine the ratio of the two peak area values ​​(larger area value / smaller area value). If this peak area value ratio is 1.2 or greater, the peak is considered to be broad. The presence or absence of a broad peak can be determined by the ratio of the length L of the baseline in the range of 165 ppm to 185 ppm to the length L' of the perpendicular line from the peak top to the baseline. That is, if the ratio L' / L is 0.1 or greater, it can be determined that a broad peak is present. The ratio L' / L may be 0.2 or greater, 0.3 or greater, 0.4 or greater, or 0.5 or greater. The upper limit of the ratio L' / L is not particularly limited, but it is usually 3.0 or less, or may be 2.0 or less, or 1.0 or less.

[0040] The structure of the glucopyranose ring can also be determined by analysis according to the method described in Sustainable Chem. Eng. 2020, 8, 48, 17800-17806.

[0041] (Viscosity Average Degree of Polymerization) The viscosity average degree of polymerization of oxidized cellulose is preferably 30-500, more preferably 60-300, even more preferably 70-150, and particularly preferably 80-130.

[0042] The viscosity average degree of polymerization is the average degree of polymerization measured by a viscosity method. The viscosity average degree of polymerization can be measured by the method described in WO 2022 / 009979.

[0043] [Method for producing oxidized cellulose] Oxidized cellulose can be produced by oxidizing a cellulosic raw material with hypochlorous acid or a salt thereof. Specific production methods include those described in WO 2022 / 009979 and WO 2022 / 009980. Oxidized cellulose is also available as a commercially available product, such as Aronfibro (registered trademark) manufactured by Toagosei Co., Ltd.

[0044] [Nanocellulose] Hereinafter, unless otherwise specified, "nanocellulose" refers to an oxide of a cellulose-based raw material with hypochlorous acid or a salt thereof, after defibration.

[0045] Nanocellulose is a general term for micronized cellulose, and includes micronized cellulose fibers, etc. Micronized cellulose fibers are also called cellulose nanofibers (CNF).

[0046] Nanocellulose preferably has a carboxyl group. The carboxyl group may be in the H type (—COOH) or in the salt type. The type of salt is not particularly limited, but examples include alkali metal salts such as lithium salt, sodium salt, and potassium salt; alkaline earth metal salts such as calcium salt and barium salt; other metal salts such as magnesium salt and aluminum salt; ammonium salt; and organic amine salts.

[0047] Nanocellulose is a collection of individual fibers. When nanocellulose contains carboxylated nanocellulose, it is sufficient that it contains at least one carboxylated nanocellulose, and it is preferable that carboxylated nanocellulose is the main component. Here, carboxylated nanocellulose being the main component means that the proportion of carboxylated nanocellulose in the total amount of nanocellulose exceeds 50% by mass, preferably exceeds 70% by mass, and more preferably exceeds 80% by mass. The upper limit of the above proportion is 100% by mass, but it may also be 98% by mass or 95% by mass.

[0048] (N-oxyl compounds) Nanocellulose is preferably substantially free of N-oxyl compounds. The meaning of nanocellulose being "substantially free of N-oxyl compounds" and the method for measuring the content of N-oxyl compounds shall follow the description in the (N-oxyl compounds) section of [Oxidized Cellulose] above.

[0049] (Carboxy group amount) The carboxy group amount of nanocellulose and the method for measuring it shall follow the description in the (Carboxy group amount) column of [Oxidized cellulose] above.

[0050] (Average fiber length) The average fiber length of nanocellulose is preferably 50 to 3000 nm, more preferably 50 to 700 nm, even more preferably 50 to 500 nm, still more preferably 60 to 300 nm, and particularly preferably 70 to 200 nm.

[0051] (Average fiber width) The average fiber width of nanocellulose is preferably 1 to 20 nm, more preferably 1 to 15 nm, even more preferably 1 to 10 nm, and particularly preferably 1 to 5 nm.

[0052] The average fiber length and average fiber width of nanocellulose can be measured by the method described in WO 2022 / 009980.

[0053] (Aspect ratio) The aspect ratio of nanocellulose (average fiber length / average fiber width) is preferably 20 to 1000, more preferably 20 to 200, even more preferably 30 to 190, and particularly preferably 40 to 180.

[0054] (Zeta potential) The zeta potential of nanocellulose is preferably −30 mV or less, more preferably −90 mV or more and −30 mV or less, even more preferably −80 mV or more and −30 mV or less, still more preferably −70 mV or more and −30 mV or less, and particularly preferably −65 mV or more and −35 mV or less.

[0055] The zeta potential can be measured by the method described in WO 2022 / 009980.

[0056] (Crystallization degree) The crystallinity of nanocellulose is preferably 10 to 70%, more preferably 20 to 70%, even more preferably 30 to 65%, particularly preferably 40 to 60%, and most preferably 50 to 55%. The method for measuring crystallinity is as described in the examples below.

[0057] [Method for producing nanocellulose] Nanocellulose can be produced by defibrating the above-mentioned oxidized cellulose. Specific production methods include those described in WO 2022 / 009979 and WO 2022 / 009980. Nanocellulose can also be obtained by defibrating commercially available oxidized cellulose products (for example, Aronfibro (registered trademark) manufactured by Toagosei Co., Ltd.).

[0058] [Sugars having ionic groups] The resin composition according to this embodiment contains sugars having ionic groups. In this specification, chemically modified nanocellulose is not included in the sugars having ionic groups.

[0059] As used herein, the term "ionic group" refers to a group that is ionized or that becomes ionized in water.

[0060] Examples of the ionic group include an anionic group and a cationic group. From the viewpoint of forming a molded article having a superior storage modulus, the ionic group is preferably an anionic group.

[0061] Examples of the anionic group include a carboxy group, a sulfate group, a sulfonate group, and a phosphate group. Of these, the carboxy group and the sulfate group are preferred.

[0062] Examples of saccharides having an ionic group include carboxymethylcellulose or a salt thereof, and alginic acid or a salt thereof.

[0063] The amount of the saccharide having an ionic group is preferably 0.1 to 30% by mass, more preferably 1 to 20% by mass, and even more preferably 3 to 10% by mass, based on the mass of the water-soluble resin.

[0064] [Water-Soluble Resin] The resin composition according to this embodiment contains a water-soluble resin.

[0065] In this specification, the term "water-soluble resin" refers to a resin having a solubility of 0.1 g or more in 100 g of water at 25°C.

[0066] The water-soluble resin is preferably a resin having film-forming ability.

[0067] Examples of the water-soluble resin include polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, poly(meth)acrylic acid, polyvinyl ether, polyethylene oxide, and polyvinyl acetal. Although not particularly limited, the water-soluble resin is preferably polyvinyl alcohol.

[0068] Polyvinyl alcohol can be obtained, for example, by saponifying polyvinyl ester obtained by polymerizing vinyl esters, such as vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, and vinyl versatate.

[0069] During polymerization of the vinyl ester, other copolymerizable monomers may be copolymerized within a range that allows water solubility to be maintained. Examples of the monomer copolymerizable with the vinyl ester include olefins having 2 to 30 carbon atoms, (meth)acrylic acid or a salt thereof, (meth)acrylic acid esters, (meth)acrylamide derivatives, vinyl ethers, nitriles, vinyl halides, allyl compounds, maleic acid or a salt thereof or an ester thereof, itaconic acid or a salt thereof or an ester thereof, vinylsilyl compounds, isopropenyl acetate, dihydroxybutene derivatives, vinyl ethyl carbonate, 3,4-diacetoxy-1-butene, and 3,4-diethoxy-1-butene.

[0070] The copolymerization ratio of the monomer copolymerizable with the vinyl ester is preferably 15 mol % or less, more preferably 10 mol % or less. The lower limit of the copolymerization ratio may be, for example, 0.01 mol % or 0.05 mol %.

[0071] The saponification degree of the polyvinyl ester is preferably 70 mol % or more, more preferably 80 mol % or more, and the upper limit of the saponification degree may be, for example, 100 mol % or 99.8 mol %.

[0072] The degree of polymerization of polyvinyl alcohol is preferably 500 to 8,000, more preferably 1,000 to 4,000.

[0073] The degree of saponification is a value measured in accordance with the test method of JIS-K-6726:1994.

[0074] The degree of polymerization (Po) is a value measured in accordance with the JIS-K-6726:1994 test method, and is calculated from the intrinsic viscosity [η] (dl / g) measured in water at 30°C after resaponifying and purifying polyvinyl alcohol, using the following formula: Po = ([η] × 103 / 8.29) (1 / 0.62).

[0075] [Additives] The resin composition according to the present embodiment may further contain additives, such as plasticizers, surfactants, crosslinking agents, antioxidants, ultraviolet absorbers, flame retardants, fillers, leveling agents, antifoaming agents, thickeners, and dyes.

[0076] <Molded Article> One embodiment of the present invention relates to a molded article obtained by molding the above-described resin composition.

[0077] Examples of the molded article include films (including packaging materials, etc.).

[0078] The method for producing the molded article is not particularly limited, and any known method may be used depending on the shape of the molded article. For example, when the molded article is a film, its production method may include, for example, a casting film-forming method, a solution coating method, a wet film-forming method, a gel film-forming method, and a melt extrusion film-forming method. The obtained film may be subjected to uniaxial or biaxial stretching.

[0079] <Adhesive> One embodiment of the present invention relates to an adhesive containing the resin composition described above.

[0080] The adhesive preferably further contains a solvent, which is preferably water.

[0081] The adhesive may be applied by, for example, applying the adhesive and then drying it.

[0082] <Other Applications> The resin composition according to this embodiment can be used, for example, for prepreg. Prepreg refers to a fiber sheet or tape pre-impregnated with a resin in a fiber-reinforced composite material using fibers such as carbon fiber, glass fiber, or Kevlar fiber. Prepreg can be used in fields such as aerospace, automobiles, wind turbine blades, and sporting goods. Prepreg can also be used for heat sinks, which are radiators for efficiently dissipating heat from electronic devices and power equipment.

[0083] The present invention will be described in more detail below using examples and comparative examples, but the technical scope of the present invention is not limited thereto. Various values ​​in the examples may be used as preferred lower or upper limits in the embodiments of the present invention. Furthermore, two values ​​of the same type in the examples may be appropriately combined to form a preferred numerical range.

[0084] <Preparation of Cellulose> [Production Example 1] (Oxidation Step) Pulp (KC Flock W100GK, Nippon Paper Industries Co., Ltd.) was used as the cellulosic raw material. 350 g of sodium hypochlorite pentahydrate crystals with an effective chlorine concentration of 42% by mass were placed in a beaker, and pure water was added and stirred to obtain a sodium hypochlorite aqueous solution with an effective chlorine concentration of 21% by mass. 35% by mass of hydrochloric acid was then added and stirred to adjust the pH to 11.0. This sodium hypochlorite aqueous solution was heated to 30°C in a thermostatic water bath while stirring at 200 rpm using a propeller-type stirring blade in a Shinto Scientific mixer (Three-One Motor, BL600), and 50 g of the pulp was then added. After adding the cellulosic raw material, the solution was kept at 30°C in the same thermostatic water bath while adding a 48% by mass aqueous sodium hydroxide solution to maintain the pH at 11.0 during the reaction. The mixture was stirred at 200 rpm using a propeller-type stirring blade, and the oxidation reaction was carried out for 4 hours (pH was maintained). After the reaction was completed, the mixture was filtered using a filter cloth (manufactured by Nakao Filter Co., Ltd., KE022, air permeability 0.3 cc / cm ２ The product was subjected to solid-liquid separation by pressure filtration using a pressure filtration filter (pressure filtration / sec), and the resulting oxidized cellulose solid was washed with pure water. The amount of carboxy groups in the oxidized cellulose was 0.7 mmol / g.

[0085] (Measurement of effective chlorine concentration in sodium hypochlorite aqueous solution) The effective chlorine concentration in the sodium hypochlorite aqueous solution was measured by the following method. 0.582 g of an aqueous solution prepared by adding sodium hypochlorite pentahydrate crystals to pure water was precisely weighed, 50 mL of pure water was added, 2 g of potassium iodide and 10 mL of acetic acid were added, and the container was immediately sealed and left in the dark for 15 minutes. After leaving the container for 15 minutes, the liberated iodine was titrated with 0.1 mol / L sodium thiosulfate solution (solution factor 1.000) (indicator: starch test solution), and the titration amount was 34.55 mL. A blank test was separately performed to correct for this, and since 1 mL of 0.1 mol / L sodium thiosulfate solution corresponds to 3.545 mg Cl, the effective chlorine concentration in the sodium hypochlorite aqueous solution was 21% by mass.

[0086] (Defibrillation process) An aqueous dispersion of Na-type oxidized cellulose (solid content 5.0% by mass) was treated with a homomixer (Robomix, manufactured by TOKUSHU KIKA) at 10,000 rpm for 40 minutes using 500 g of liquid to defibrate the oxidized cellulose into nanocellulose, obtaining an aqueous nanocellulose dispersion. The resulting aqueous nanocellulose dispersion was diluted with pure water to adjust the solid content to 2.0% by mass. The average fiber length of the resulting nanocellulose was 120 nm, the average fiber width was 3 nm, and the aspect ratio calculated from these results was 40. Furthermore, the crystallinity was 53%.

[0087] (Measurement of average fiber width and average fiber length) Pure water was added to the aqueous dispersion of nanocellulose to adjust the nanocellulose concentration in the aqueous dispersion to 5 ppm. After adjusting the concentration, the aqueous dispersion was air-dried on a mica substrate, and the shape of the nanocellulose was observed in AC mode using an Oxford Asylum scanning probe microscope "MFP-3D infinity." The average fiber length was determined by binarizing the obtained images using the image processing software "ImageJ." For 100 or more fibers, the average fiber length was calculated as fiber length = "perimeter" ÷ 2. For the average fiber width, the software included with the "MFP-3D infinity" was used to calculate the number average fiber width [nm] for 50 or more fibers, where the cross-sectional height of the shape image = fiber width.

[0088] Crystallinity was measured using solid nanocellulose for freeze-dried nanocellulose. １３ C-NMR measurements were performed and the crystallinity was calculated from the peak of the fourth carbon (C4) of nanocellulose. Specifically, the C4 peak appears in the range of approximately 80 to 95 ppm, with the peaks of the crystalline portion (high ppm side, approximately 85 to 95 ppm) and the amorphous portion (low ppm side) overlapping. Therefore, the area of ​​each peak was divided by the vertical division method and determined using the following formula. A more specific measurement method is as described in WO 2022 / 138759. Crystallinity = SC / (SC + SA) x 100 [where SC is the crystalline portion and SA is the amorphous portion.]

[0089] [Production Example 2] Nanocellulose obtained by TEMPO oxidation was obtained by production in accordance with Angew. Chem. Int. Ed. 2021, 60, 24630-24636. That is, it was produced by the following method. 0.016 g of TEMPO and 0.1 g of sodium bromide were placed in a beaker, pure water was added and stirred to obtain an aqueous solution, and 1.0 g of powdered pulp (KC Flock W-100GK) from Nippon Paper Industries Co., Ltd. was added as a cellulose-based raw material. The above aqueous solution was heated to 25 ° C. in a constant temperature water bath while stirring with a stirrer, and then 0.1 mol / g sodium hydroxide was added and stirred to obtain an aqueous solution with a pH of 10.0. To this was added 2.58 g of an aqueous sodium hypochlorite solution with an effective chlorine concentration of 13.2% by mass. The mixture was then kept at 25°C in the same thermostatic water bath. During the reaction, 0.1 mol / L sodium hydroxide was added to adjust the pH to 10.0, and the mixture was stirred with a stirrer for 120 minutes. After completion of the reaction, the product was subjected to solid-liquid separation by suction filtration using a PTFE membrane filter with a mesh size of 0.1 μm to obtain oxidized cellulose. The resulting filtered material was washed with purified water and then the amount of carboxy groups was measured. The amount of carboxy groups was 1.55 mmol / g, and the amount of filtered material was approximately 1.0 g. Furthermore, the nitrogen component derived from N-oxyl compounds in the oxidized cellulose was measured as the amount of nitrogen using a trace total nitrogen analyzer (formerly manufactured by Toseiko Analytech Co., Ltd., device name: TN-2100H). The increase from the raw pulp was calculated to be 5 ppm. This oxidized cellulose was mechanically defibrated to obtain a nanocellulose aqueous dispersion (solid content 2.0% by mass) obtained by TEMPO oxidation. Furthermore, it was confirmed that the average fiber length of the obtained nanocellulose was in the range of 500-2,000 nm, and the average fiber width was in the range of 3-5 nm. The aspect ratio calculated from these results was confirmed to be 100-666. Furthermore, it was confirmed that the crystallinity was in the range of 60-70%.

[0090] Comparative Manufacturing Example 1: Commercially available powdered cellulose was defibrated using a Starburst to obtain a chemically unmodified aqueous nanocellulose dispersion (solid content 2.0% by mass) obtained by mechanical defibration. Furthermore, it was confirmed that the average fiber length of the obtained nanocellulose was in the range of 5 to 20 μm and the average fiber width was in the range of 10 to 50 nm. The aspect ratio calculated from these results was confirmed to be 100 to 2,000. Furthermore, it was confirmed that the crystallinity was in the range of 70 to 80%.

[0091] Comparative Production Example 2 Cellulose nanocrystal (CNC) manufactured by Filler Bank Co., Ltd. was obtained. It was confirmed that the average fiber length of the obtained nanocellulose was in the range of 400 to 600 nm and the average fiber width was in the range of 5 to 10 nm, and that the aspect ratio calculated from these results was 40 to 120. Furthermore, the crystallinity was 98% or more.

[0092] <Measurement of Storage Modulus> [Example 1] 392 g of pure water was added to a beaker, which was then immersed in an ice bath for 10 minutes to bring the liquid temperature to 0°C. The ice-cooled pure water was placed in a homomixer (Robomix, manufactured by Tokushu Kikka) and stirred at 2,000 rpm. A total of 8 g of pelletized polyvinyl alcohol (PVA) (GH-20R, manufactured by Mitsubishi Chemical Corporation) was added in several portions to a concentration of 2.0% by mass. After confirming that the PVA was sufficiently dispersed in the pure water through stirring, stirring was stopped, the beaker was removed from the ice bath, and the beaker was immersed in a water bath at room temperature. Stirring was resumed at 2,000 rpm using the homomixer, and heating was resumed until the water temperature finally reached 100°C. After stirring for 5 minutes in the water bath at a water temperature of 100°C, the beaker was removed from the water bath and allowed to cool at room temperature for 3 hours. After confirming that the temperature of the solution had cooled to room temperature, 20 g of the resulting PVA aqueous solution was poured into a plastic container. The solution was then heated on a hot plate (EC-1200N, manufactured by AS ONE Corporation) at 45°C for 8 hours to evaporate the water content of the PVA aqueous solution, forming a film. The film was then vacuum-dried at 50°C and -100 kPa for 15 hours using a vacuum dryer (DRV320DA, manufactured by Advantec Corporation) to completely remove the water content. The resulting dried film was weighed to be 2.0 g, confirming that a 2% by mass PVA aqueous solution had been prepared.

[0093] 25 g of a 2% by mass PVA aqueous solution was collected and transferred to a 50 ml screw tube. 2.5 g of the nanocellulose aqueous dispersion (solid content: 2% by mass) from Production Example 1 was added to the screw tube so that the solid content (CNF) was 10 parts per 100 parts of PVA. Also, 0.025 g of sodium salt of carboxymethyl cellulose (CMC) (manufactured by Daicel Corporation, 2200) was added to the screw tube so that the CMC was 5 parts per 100 parts of PVA.

[0094] The screw tube was mixed at 50 rpm for 24 hours using a MIX rotor (MX-T6-S, manufactured by DLAB SCIENTIFIC CO., LTD.). Then, the mixture was mixed at 2,000 rpm for 3 minutes using a rotation-revolution mixer (ARE-310, Awatori Rentaro, manufactured by THINKY Corporation). Next, a stirrer tip was placed in the mixed screw tube, and the mixture was degassed by stirring with a magnetic stirrer for 15 minutes in a vacuum-controlled desiccator. The entire amount of the resulting solution was poured into a plastic container and heated on a hot plate at 45°C for 15 hours to evaporate the water, producing a film with a thickness of approximately 100 μm. The resulting film was dried at room temperature for 1 day, then cut into 1 cm x 4 cm strips, and the storage modulus was measured using a dynamic viscoelasticity measuring device (DMS6100, manufactured by Hitachi High-Tech Science Corporation).

[0095] Comparative Example 1A A film was prepared and measured in the same manner as in Example 1, except that CMC was not used.

[0096] Comparative Example 1B A film was produced and measured in the same manner as in Example 1, except that CNF was not used.

[0097] Comparative Example 1C A film was produced and measured in the same manner as in Example 1, except that CMC and CNF were not used.

[0098] The measurement results of the above Examples and Comparative Examples are shown in Table 1. The storage modulus values ​​in Table 1 are ratios to the storage modulus of Comparative Example 1C. As can be seen from the results in Table 1, the storage modulus was significantly increased by using a combination of CMC and CNF.

[0099]

[0100] [Example 2] A film was prepared in the same manner as in Example 1, except that the nanocellulose aqueous dispersion of Production Example 2 (TEMPO oxidation) was used instead of the nanocellulose aqueous dispersion of Production Example 1 (hypochlorous acid oxidation). A measurement was performed.

[0101] [Comparative Example 2A] A film was produced in the same manner as in Example 1, except that the nanocellulose aqueous dispersion of Comparative Production Example 1 (mechanically defibrated) was used instead of the nanocellulose aqueous dispersion of Production Example 1 (hypochlorous acid oxidation). A measurement was performed.

[0102] [Comparative Example 2B] A film was prepared in the same manner as in Example 1, except that the cellulose nanocrystal (CNC) of Comparative Production Example 2 was used instead of the nanocellulose aqueous dispersion of Production Example 1 (hypochlorous acid oxidation). A measurement was performed.

[0103] The measurement results of the above Examples and Comparative Examples are shown in Table 2. The storage modulus values ​​in Table 2 are ratios to the storage modulus when CMC is omitted from each Example and Comparative Example. For example, the storage modulus value of Example 1 is the ratio to the storage modulus when CMC is omitted from Example 1, and the storage modulus value of Example 2 is the ratio to the storage modulus when CMC is omitted from Example 2. As can be seen from the results in Table 2, the storage modulus was significantly increased by using CNF oxidized with hypochlorous acid or TEMPO (particularly CNF oxidized with hypochlorous acid) in combination with CMC.

[0104]

[0105] Example 3 and Comparative Examples 3A to 3E Films were prepared in the same manner as in Example 1, except that the CMC in Example 1 was changed to the various components shown in Table 3, and measurements were carried out.

[0106] The measurement results of the above Examples and Comparative Examples are shown in Table 3. The storage modulus values ​​in Table 3 are the ratios to the storage modulus when CMC or its substitute (sodium alginate, etc.) is omitted from each Example and Comparative Example. For example, the storage modulus value of Example 1 is the ratio to the storage modulus when CMC is omitted from Example 1, and the storage modulus value of Example 3 is the ratio to the storage modulus when sodium alginate is omitted from Example 3. As can be seen from the results in Table 3, the storage modulus was increased by using a combination of sugars having a carboxy group and CNF.

[0107]

Claims

1. A resin composition comprising: chemically modified nanocellulose; a saccharide having an ionic group; and a water-soluble resin.

2. The resin composition according to claim 1, wherein the crystallinity of the chemically modified nanocellulose is 10 to 70%.

3. The resin composition according to claim 1, wherein the average fiber length of the chemically modified nanocellulose is 50 to 3,000 nm.

4. The resin composition according to claim 1, wherein the average fiber width of the chemically modified nanocellulose is 1 to 20 nm.

5. The resin composition according to claim 1, wherein the aspect ratio of the chemically modified nanocellulose is 20 to 1,000.

6. The resin composition according to claim 1, wherein the chemically modified nanocellulose has a carboxy group.

7. The resin composition according to claim 1, wherein the chemically modified nanocellulose is oxidized nanocellulose.

8. The resin composition according to claim 1, wherein the chemically modified nanocellulose comprises an oxidation product of a cellulose-based raw material with hypochlorous acid or a salt thereof, and is substantially free of N-oxyl compounds.

9. The resin composition according to claim 1, wherein the chemically modified nanocellulose has a structure in which the second and third hydroxyl groups of the glucopyranose ring are oxidized and dicarboxy groups are introduced.

10. The resin composition according to claim 1, wherein the ionic group of the saccharide comprises a carboxyl group and / or a sulfate group.

11. A molded article of the resin composition according to any one of claims 1 to 10.

12. The molded article according to claim 11, which is a film.

13. An adhesive comprising the resin composition according to any one of claims 1 to 10.

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