Active energy ray-curable composition, cured product and method for producing same

Abstract

An active energy ray-curable composition according to the present invention contains modified nanocellulose and an active energy ray-curable monomer. The modified nanocellulose contains nanocellulose and a modifying group introduced into the nanocellulose. The modifying group is introduced into at least some of the hydroxyl groups of the nanocellulose via covalent bonds. The modifying group has a carbon-carbon unsaturated bond.

Description

Active energy ray curable composition, cured product, and method for producing the same

[0001] The present invention relates to an active energy ray-curable composition, a cured product, and a method for producing the same.

[0002] Active energy ray-curable compositions that are cured by irradiation with active energy rays such as ultraviolet rays have a short curing time, are excellent in productivity, and are energy-saving, and therefore are used in a variety of applications such as printing inks, paints, electronic components, optical members, and building materials. However, cured products of active energy ray-curable compositions generally have the drawback of being brittle and lacking in toughness.

[0003] In recent years, nanocellulose has been proposed as an effective filler. Nanocellulose is a fine fiber made from cellulose, primarily derived from plants. Nanocellulose has attracted attention due to its extremely high crystalline modulus of elasticity (100 GPa or more) and its low environmental impact. For example, Patent Document 1 discloses that a cured product of an active energy ray-curable composition containing nanocellulose and an active energy ray-curable monomer has excellent strength.

[0004] Furthermore, for example, Non-Patent Document 1 discloses that carboxy groups on the surface of cellulose nanofibers (CNFs) oxidized with 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) are modified with amines.

[0005] JP 2023-11092 A

[0006] Cellulose. Vol. 29 (2022): 2839-2853

[0007] An object of the present invention is to provide an active energy ray-curable composition capable of forming a cured product having excellent strength (maximum stress).

[0008] As a result of intensive research, the present inventors have found that by combining modified nanocellulose with an active energy ray-curable monomer, a cured product with excellent strength can be formed.

[0009] The present invention includes the following embodiments. [1] An active energy ray-curable composition comprising: modified nanocellulose; and an active energy ray-curable monomer, wherein the modified nanocellulose comprises: nanocellulose; and a modifying group introduced into the nanocellulose, wherein the modifying group is introduced to at least some of the hydroxyl groups of the nanocellulose via a covalent bond, and the modifying group has a carbon-carbon unsaturated bond. [1-1] The active energy ray-curable composition according to [1], wherein the carbon-carbon unsaturated bond is a double bond. [1-2] The active energy ray-curable composition according to [1] or [1-1], wherein the carbon-carbon unsaturated bond is an ethylenic double bond. [1-3] The active energy ray-curable composition according to any of [1] to [1-2], wherein the active energy ray-curable monomer is a compound having an ethylenic unsaturated group. [1-4] The active energy ray-curable composition according to [1-3], wherein the ethylenically unsaturated group is at least one selected from the group consisting of a (meth)acryloyl group, a vinyl group, and a vinyl ether group. [2] The active energy ray-curable composition according to any one of [1] to [1-4], wherein the nanocellulose has a structure in which dicarboxy groups are introduced by oxidizing the hydroxyl groups at the second and third positions of the glucopyranose ring. [3] The active energy ray-curable composition according to any one of [1] to [2], wherein the 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. [4] The active energy ray-curable composition according to any one of [1] to [3], wherein the ratio of the breaking elongation of a cured product obtained by curing the active energy ray-curable composition to the breaking elongation of a control cured product obtained by curing a control composition obtained by omitting the modified nanocellulose from the active energy ray-curable composition is 0.60 or more. [4-1] The active energy ray-curable composition according to [4], wherein the ratio of the values ​​of elongation at break is 0.60 to 5.0. [4-2] The active energy ray-curable composition according to [4], wherein the ratio of the values ​​of elongation at break is 0.80 to 4.0.[4-3] The active energy ray-curable composition according to [4], wherein the ratio of the breaking elongation values ​​is 1.0 to 3.0. [5] The active energy ray-curable composition according to any one of [1] to [4-3], wherein the ratio of the maximum stress value of a cured product obtained by curing the active energy ray-curable composition to the maximum stress value of a control cured product obtained by curing a control composition in which the modified nanocellulose is omitted from the active energy ray-curable composition is 2.0 or more. [5-1] The active energy ray-curable composition according to [5], wherein the ratio of the maximum stress values ​​is 2.0 to 10.0. [5-2] The active energy ray-curable composition according to [5], wherein the ratio of the maximum stress values ​​is 3.0 to 8.0. [5-3] The active energy ray-curable composition according to [5], wherein the ratio of the maximum stress values ​​is 4.0 to 7.0. [6] The active energy ray-curable composition according to any one of [1] to [5-3], wherein the ratio of the value of the modulus of elasticity of a cured product obtained by curing the active energy ray-curable composition to the value of the modulus of elasticity of a control cured product obtained by curing a control composition obtained by omitting the modified nanocellulose from the active energy ray-curable composition is 1.1 or more. [6-1] The active energy ray-curable composition according to [6], wherein the ratio of the values ​​of the modulus of elasticity is 1.1 to 9.0. [6-2] The active energy ray-curable composition according to [6], wherein the ratio of the values ​​of the modulus of elasticity is 2.0 to 7.0. [6-3] The active energy ray-curable composition according to [6], wherein the ratio of the values ​​of the modulus of elasticity is 3.0 to 5.0. [7] The active energy ray-curable composition according to any one of [1] to [6-3], wherein the ratio of the value of the work of rupture of a cured product obtained by curing the active energy ray-curable composition to the value of the work of rupture of a control cured product obtained by curing a control composition obtained by omitting the modified nanocellulose from the active energy ray-curable composition is 1.5 or more. [7-1] The active energy ray-curable composition according to [7], wherein the ratio of the values ​​of the work of breaking is 1.5 to 10.0. [7-2] The active energy ray-curable composition according to [7], wherein the ratio of the values ​​of the work of breaking is 2.5 to 8.0. [7-3] The active energy ray-curable composition according to [7], wherein the ratio of the values ​​of the work of breaking is 3.5 to 6.0.[8] The hydroxyl group to which the modifying group has been introduced is represented by the following formula (1): R: １ -C(=O)-O- (1) [R １ [8-1] The active energy ray-curable composition according to any one of [1] to [7-3], wherein R is a substituted or unsubstituted alkenyl group, or a substituted or unsubstituted cycloalkenyl group. １ [8-2] The active energy ray-curable composition according to [8], wherein R is a substituted or unsubstituted alkenyl group. １ [8-3] The active energy ray-curable composition according to [8] or [8-1], wherein R is a substituted alkenyl group. １ [9] The active energy ray-curable composition according to any one of [8] to [8-2], wherein R is an alkenyl group substituted with a carboxy group. １is an unsubstituted alkenyl group.

[10] The active energy ray-curable composition according to any one of [1] to [9], wherein the modifying group is derived from at least one compound selected from the group consisting of a monocarboxylic acid compound having a carbon-carbon unsaturated bond and a dicarboxylic acid compound having a carbon-carbon unsaturated bond. [11A] The active energy ray-curable composition according to

[10] , wherein the modifying group is derived from a monocarboxylic acid compound having a carbon-carbon unsaturated bond, and the monocarboxylic acid compound comprises at least one selected from the group consisting of (meth)acrylic acid, 2-ethylacrylic acid, 2-propylacrylic acid, and 2-isopropylacrylic acid.

[11] The active energy ray-curable composition according to

[10] or [11A], wherein the modifying group is derived from a monocarboxylic acid compound having a carbon-carbon unsaturated bond, and the monocarboxylic acid compound comprises (meth)acrylic acid. [12A] The active energy ray-curable composition according to

[10] , wherein the modifying group is derived from a dicarboxylic acid compound having a carbon-carbon unsaturated bond, and the dicarboxylic acid compound comprises at least one selected from the group consisting of maleic acid, fumaric acid, itaconic acid, and succinic acid substituted with an alkenyl group.

[12] The active energy ray-curable composition according to

[10] or [12A], wherein the modifying group is derived from a dicarboxylic acid compound having a carbon-carbon unsaturated bond, and the dicarboxylic acid compound comprises maleic acid and / or itaconic acid.

[13] The active energy ray-curable composition according to any of [1] to

[12] , wherein the average fiber width of the modified nanocellulose is 1 to 50 nm. [13-1] The active energy ray-curable composition according to any of [1] to

[13] , wherein the average fiber width of the modified nanocellulose is 1 to 20 nm. [13-2] The active energy ray-curable composition according to any one of [1] to [13-1], wherein the average fiber width of the modified nanocellulose is 1 to 15 nm. [13-3] The active energy ray-curable composition according to any one of [1] to [13-2], wherein the average fiber width of the modified nanocellulose is 1 to 10 nm.[13-4] The active energy ray-curable composition according to any one of [1] to [13-3], wherein the average fiber width of the modified nanocellulose is 1 to 5 nm.

[14] The active energy ray-curable composition according to any one of [1] to [13-4], wherein the average fiber length of the modified nanocellulose is 50 to 3,000 nm. [14-1] The active energy ray-curable composition according to any one of [1] to

[14] , wherein the average fiber length of the modified nanocellulose is 50 to 700 nm. [14-2] The active energy ray-curable composition according to any one of [1] to [14-1], wherein the average fiber length of the modified nanocellulose is 50 to 500 nm. [14-3] The active energy ray-curable composition according to any one of [1] to [14-2], wherein the average fiber length of the modified nanocellulose is 60 to 300 nm. [14-4] The active energy ray-curable composition according to any one of [1] to [14-3], wherein the average fiber length of the modified nanocellulose is 70 to 200 nm.

[15] The active energy ray-curable composition according to any one of [1] to [14-4], further comprising a photopolymerization initiator. [15-1] The active energy ray-curable composition according to any one of [1] to [14-4], which does not comprise a photopolymerization initiator.

[16] A cured product of the active energy ray-curable composition according to any one of [1] to [15-1].

[17] A method for producing a cured product, comprising: a step of irradiating the active energy ray-curable composition according to any one of [1] to [15-1] with active energy rays to cure the composition.

[0010] The present invention can provide an active energy ray-curable composition capable of forming a cured product having excellent strength.

[0011] FIG. 1 shows the relationship between the breaking elongation (%) and the maximum stress (kPa) of the sheet-like cured products obtained in the Examples and Comparative Examples.

[0012] 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.

[0013] As used herein, "(meth)acrylate" refers to acrylate and methacrylate. As used herein, "(meth)acryloyl" refers to acryloyl and methacryloyl. As used herein, "(meth)acrylic" refers to acrylic and methacrylic.

[0014] <Active energy ray-curable composition> One embodiment of the present invention relates to an active energy ray-curable composition comprising modified nanocellulose and an active energy ray-curable monomer, wherein the modified nanocellulose comprises nanocellulose and a modifying group introduced into the nanocellulose, the modifying group being introduced via a covalent bond to at least some of the hydroxyl groups of the nanocellulose, and the modifying group having a carbon-carbon unsaturated bond.

[0015] The cured product formed from the active energy ray-curable composition according to this embodiment has excellent strength. The reasons for this are presumed to be that, for example, the introduction of modifying groups into at least some of the hydroxyl groups of the nanocellulose improves the hydrophobicity of the nanocellulose, making it easier to disperse in the active energy ray-curable monomer, and that the carbon-carbon unsaturated bonds contained in the modifying groups form a crosslinked structure between the modified nanocellulose and the active energy ray-curable monomer, but the present invention is not limited by these reasons.

[0016] [Properties] A cured product of the active energy ray-curable composition preferably has the following properties when formed and measured under the following conditions.

[0017] (Formation of Cured Product) Each of the active energy ray-curable composition and the control composition was poured into a mold having a thickness of 1 mm, and the cured product was cured under an integrated illuminance of 5000 mW / cm ２The control composition is a composition obtained by excluding the modified nanocellulose from the active energy ray-curable composition. Therefore, the control composition can be prepared using the same types and amounts of components as the active energy ray-curable composition, except that the modified nanocellulose is not used. The target cured product is obtained by curing the target composition.

[0018] (Measurement of cured product) A rectangular test piece (thickness: approximately 1 mm) with a total length of 50 mm and a width between gauge marks of 5 mm is cut out from the sheet-like cured product. A tensile test is performed on this test piece using a tensile tester at 23±2°C, a gauge mark distance of 10 mm, and a tensile speed of 100 mm / min according to JIS K6251, and the breaking elongation, maximum stress, elastic modulus, and work at break are measured.

[0019] (Elongation at break) The ratio of the elongation at break of a cured product obtained by curing an active energy ray-curable composition to the elongation at break of a control cured product obtained by curing a control composition (hereinafter referred to as the "elongation at break ratio") is preferably 0.60 or more, more preferably 0.80 or more, and even more preferably 1.0 or more. The upper limit of the elongation at break ratio is not particularly limited, but may be, for example, 5.0 or less, 4.0 or less, or 3.0 or less. The range of the elongation at break ratio can be determined by appropriately combining the above-mentioned upper and lower limits. The range of the elongation at break ratio may be, for example, 0.60 to 5.0, 0.80 to 4.0, or 1.0 to 3.0.

[0020] The elongation at break can be adjusted, for example, by changing the amount of modified nanocellulose. For example, decreasing the amount of modified nanocellulose tends to increase the elongation at break.

[0021] (Maximum Stress) The ratio of the maximum stress value of the cured product obtained by curing the active energy ray-curable composition to the maximum stress value of the control cured product obtained by curing the control composition (hereinafter referred to as "maximum stress ratio") is preferably 2.0 or more, more preferably 3.0 or more, and even more preferably 4.0 or more. The upper limit of the maximum stress ratio is not particularly limited, but may be, for example, 10.0 or less, 8.0 or less, or 7.0 or less. The range of the maximum stress ratio can be determined by appropriately combining the above-mentioned upper and lower limits. The range of the maximum stress ratio may be, for example, 2.0 to 10.0, 3.0 to 8.0, or 4.0 to 7.0.

[0022] The maximum stress can be adjusted, for example, by changing the amount of modified nanocellulose. For example, increasing the amount of modified nanocellulose tends to increase the maximum stress.

[0023] (Elastic Modulus) The ratio of the elastic modulus of a cured product obtained by curing an active energy ray-curable composition to the elastic modulus of a control cured product obtained by curing a control composition (hereinafter referred to as the "elastic modulus ratio") is preferably 1.1 or more, more preferably 2.0 or more, and even more preferably 3.0 or more. The upper limit of the elastic modulus ratio is not particularly limited, but may be, for example, 9.0 or less, 7.0 or less, or 5.0 or less. The range of the elastic modulus ratio can be determined by appropriately combining the above-mentioned upper and lower limits. The range of the elastic modulus ratio may be, for example, 1.1 to 9.0, 2.0 to 7.0, or 3.0 to 5.0.

[0024] The modulus of elasticity tends to increase by decreasing the elongation at break and increasing the maximum stress.

[0025] (Work of Breaking) The ratio of the work of breakage of a cured product obtained by curing an active energy ray-curable composition to the work of breakage of a control cured product obtained by curing a control composition (hereinafter referred to as the "work of breakage ratio") is preferably 1.5 or more, more preferably 2.5 or more, and even more preferably 3.5 or more. The upper limit of the work of breakage ratio is not particularly limited, but may be, for example, 10.0 or less, 8.0 or less, or 6.0 or less. The range of the work of breakage ratio can be determined by appropriately combining the above-mentioned upper and lower limits. The range of the work of breakage ratio may be, for example, 1.5 to 10.0, 2.5 to 8.0, or 3.5 to 6.0.

[0026] The work of rupture tends to increase with increasing elongation at break and increasing maximum stress.

[0027] [Modified Nanocellulose] The active energy ray-curable composition according to this embodiment contains modified nanocellulose. Modified nanocellulose is nanocellulose into which a modification group has been introduced. By using modified nanocellulose, it is possible to form a cured product with excellent strength.

[0028] The amount of modified nanocellulose is preferably 0.1 to 20.0% by mass, more preferably 0.3 to 15.0% by mass, still more preferably 0.5 to 10.0% by mass, and particularly preferably 0.5 to 7.0% by mass, based on the mass of the active energy ray-curable monomer.

[0029] Modified nanocellulose can be obtained, for example, by reacting nanocellulose with a modifying group-introducing compound described later. Nanocellulose is cellulose that has been nanosized. Nanocellulose can be obtained, for example, by oxidizing and nanoizing a cellulosic raw material. The order of oxidation and nanoization is not particularly limited, but it is preferable to oxidize the cellulosic raw material and then nanoize it. Nanoization tends to be easier by oxidizing the cellulosic raw material first.

[0030] Examples of oxidizing agents for oxidizing cellulosic raw materials include hypochlorous acid or its salts and N-oxyl compounds, such as 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO).

[0031] From the viewpoint of forming a cured product with superior strength, it is preferable to use hypochlorous acid or a salt thereof as the oxidizing agent. That is, nanocellulose is preferably produced 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.

[0032] The present inventors have surprisingly found that when nanocellulose obtained using hypochlorous acid or a salt thereof (without using an N-oxyl compound) is mixed with an active energy ray-curable monomer, a cured product having significantly superior strength can be formed compared to when nanocellulose obtained by other methods (e.g., TEMPO oxidation) is mixed.

[0033] The following description focuses on the oxidation of cellulosic raw materials with hypochlorous acid or its salts, but nanocellulose is not limited to nanocellulose with hypochlorous acid or its salts.

[0034] [Oxidized Cellulose] Unless otherwise specified, "oxidized cellulose" in this section hereinafter refers to an oxide of a cellulosic raw material with hypochlorous acid or a salt thereof before defibration.

[0035] Examples of hypochlorous acid or salts thereof include hypochlorous acid water, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, and ammonium hypochlorite.

[0036] 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%.

[0037] The definition of the effective chlorine concentration of hypochlorous acid or a salt thereof is as described in WO 2022 / 009979.

[0038] 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.

[0039] (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).

[0040] 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."

[0041] 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.).

[0042] (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.

[0043] The amount of carboxy groups in oxidized cellulose can be measured by the method described in WO 2022 / 009979.

[0044] Oxidized cellulose preferably has a structure in which at least two of the hydroxyl groups on the glucopyranose ring that constitutes cellulose are oxidized, and more specifically, it 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.

[0045] 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.

[0046] Solid oxide of cellulosic raw materials with hypochlorous acid or its salts １３In 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.

[0047] That is, solid １３ A 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.

[0048] 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.

[0049] (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.

[0050] 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.

[0051] [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.

[0052] [Nanocellulose] Unless otherwise specified, "nanocellulose" in this section hereinafter refers to an oxide of a cellulose-based raw material with hypochlorous acid or a salt thereof, after defibration.

[0053] Nanocellulose is a general term for micronized cellulose, and includes micronized cellulose fibers, cellulose nanocrystals, etc. Micronized cellulose fibers are also called cellulose nanofibers (also referred to as CNF).

[0054] Nanocellulose preferably has a carboxy group. The carboxy 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 salts, sodium salts, and potassium salts; alkaline earth metal salts such as calcium salts and barium salts; other metal salts such as magnesium salts and aluminum salts; ammonium salts, and organic amine salts. From the viewpoint of improving dispersibility in active energy ray-curable monomers, the carboxy group is preferably in the H type.

[0055] 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.

[0056] (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.

[0057] (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.

[0058] (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.

[0059] (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.

[0060] The average fiber length and average fiber width of nanocellulose can be measured by the method described in WO 2022 / 009980.

[0061] (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.

[0062] The average fiber length, average fiber width, and aspect ratio of the modified nanocellulose are preferably in the same range as those of the nanocellulose. The average fiber length, average fiber width, and aspect ratio of the modified nanocellulose can also be measured in accordance with the description of WO 2022 / 009980, as in the measurement of nanocellulose.

[0063] (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.

[0064] The zeta potential can be measured by the method described in WO 2022 / 009980.

[0065] (Crystallinity) 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%.

[0066] Crystallinity was measured using solid nanocellulose for freeze-dried nanocellulose. １３ C-NMR measurement can be performed and the crystallinity can be calculated from the peak of the fourth carbon (C4) of nanocellulose. Specifically, the C4 peak appears in the range of about 80 to 95 ppm, with the peaks of the crystalline portion (high ppm side, about 85 to 95 ppm) and the amorphous portion (low ppm side) overlapping, so the area of ​​each peak can be divided by the vertical division method and determined from 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.]

[0067] [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.).

[0068] [First modifying group] The modified nanocellulose has a first modifying group introduced into at least some of the hydroxyl groups of the nanocellulose. The hydroxyl groups to which the first modifying group has been introduced are preferably primary hydroxyl groups.

[0069] The bond between the first modifying group and the nanocellulose is a covalent bond, preferably an ester bond. The ester bond is preferably composed of oxygen (O) derived from the hydroxyl group of the nanocellulose and a carbonyl group (CO) derived from the first modifying group-introducing compound described below.

[0070] The first modifying group has a carbon-carbon unsaturated bond (hereinafter simply referred to as "unsaturated bond"). The unsaturated bond is preferably a double bond or a triple bond, more preferably a double bond, and even more preferably an ethylenic double bond. The number of unsaturated bonds is not particularly limited, and it is sufficient that there is at least one.

[0071] The hydroxyl group of nanocellulose into which the first modifying group has been introduced is preferably represented by the following formula (1): R １ -C(=O)-O- (1)

[0072] R in formula (1) １ is an alkenyl group or a cycloalkenyl group. The alkenyl group may be linear or branched.

[0073] R １ The alkenyl group preferably has 2 to 8 carbon atoms, more preferably 2 to 5 carbon atoms, and even more preferably 2 to 3 carbon atoms.

[0074] R １The cycloalkenyl group preferably has 3 to 14 carbon atoms, more preferably 4 to 10 carbon atoms, and even more preferably 5 or 6 carbon atoms.

[0075] R １ The alkenyl group or cycloalkenyl group may be substituted or unsubstituted. Examples of the substituent include a carboxy group. From the viewpoint of improving dispersibility in active energy ray-curable monomers, the carboxy group is preferably an H type (—COOH).

[0076] From the viewpoint of forming a cured product having superior strength, R １ Preferably, the alkenyl or cycloalkenyl group is unsubstituted (ie, consisting only of carbon and hydrogen).

[0077] The first modifying group may be of one type or of multiple types.

[0078] (First modifying group-introducing compound) The first modifying group-introducing compound is a compound that is reacted with nanocellulose to introduce the first modifying group into the hydroxyl group of nanocellulose. The first modifying group-introducing compound is preferably a monocarboxylic acid compound having an unsaturated bond (hereinafter simply referred to as "unsaturated monocarboxylic acid compound") and / or a dicarboxylic acid compound having an unsaturated bond (hereinafter simply referred to as "unsaturated dicarboxylic acid compound"). In this specification, unsaturated monocarboxylic acid compounds and unsaturated dicarboxylic acid compounds also include their acid anhydrides.

[0079] The first modifying group is preferably a group derived from an unsaturated monocarboxylic acid and / or an unsaturated dicarboxylic acid, particularly the residue of an unsaturated monocarboxylic acid and / or an unsaturated dicarboxylic acid that is attached to the nanocellulose as a result of reaction of the unsaturated monocarboxylic acid and / or the unsaturated dicarboxylic acid with the nanocellulose.

[0080] Examples of unsaturated monocarboxylic acids include (meth)acrylic acid, 2-ethylacrylic acid, 2-propylacrylic acid, and 2-isopropylacrylic acid.

[0081] Unsaturated dicarboxylic acids include, for example, maleic acid, fumaric acid, itaconic acid, and alkenyl-substituted succinic acid.

[0082] The degree of modification by the modifying group (hereinafter also referred to as "degree of substitution") is preferably 0.01 to 2.5, more preferably 0.05 to 2.0, and even more preferably 0.1 to 1.8, from the viewpoint of further improving the strength of the cured product. When the modifying group contains a second modifying group (described below) in addition to the first modifying group, the above-mentioned range of the degree of modification means the sum of the modification by the first modifying group and the modification by the second modifying group. The degree of modification (degree of substitution) can be measured by the method described in the Examples.

[0083] [Second modifying group] Depending on the type of first modifying group, it may not be possible to introduce a sufficient amount of the first modifying group into the hydroxyl groups of nanocellulose. In such cases, a second modifying group may be introduced into the remaining hydroxyl groups. The second modifying group is not particularly limited as long as it is easy to introduce into the hydroxyl groups and does not adversely affect the dispersibility in the active energy ray-curable monomer.

[0084] The bond between the second modifying group and the nanocellulose is a covalent bond, preferably an ester bond. The ester bond is preferably composed of oxygen (O) derived from the hydroxyl group of the nanocellulose and a carbonyl group (CO) derived from the second modifying group-introducing compound described below.

[0085] The hydroxyl group of nanocellulose into which the second modifying group has been introduced is preferably represented by the following formula (2): R ２ -C(=O)-O- (2)

[0086] R in formula (2) ２ is a substituted or unsubstituted alkyl group or a substituted or unsubstituted cycloalkyl group. The alkyl group may be linear or branched.

[0087] R ２ The alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 or 2 carbon atoms, and even more preferably 1 carbon atom.

[0088] R ２The cycloalkyl group preferably has 3 to 14 carbon atoms, more preferably 4 to 10 carbon atoms, and even more preferably 5 or 6 carbon atoms.

[0089] R ２ The alkyl group or cycloalkyl group may be substituted or unsubstituted. Examples of the substituent include a carboxy group. From the viewpoint of improving dispersibility in active energy ray-curable monomers, the carboxy group is preferably an H type (—COOH).

[0090] From the viewpoint of forming a cured product having superior strength, R ２ Preferably, the alkyl or cycloalkyl group is unsubstituted (ie, consists only of carbon and hydrogen).

[0091] The second modifying group may be of one type or of multiple types.

[0092] (Second modifying group-introducing compound) The second modifying group-introducing compound is a compound that is reacted with nanocellulose to introduce a second modifying group into the hydroxyl group of nanocellulose. The second modifying group-introducing compound is preferably a saturated monocarboxylic acid compound. In this specification, saturated monocarboxylic acid compounds also include their acid anhydrides.

[0093] The second modifying group is preferably a group derived from a saturated monocarboxylic acid, specifically the residue of a saturated monocarboxylic acid that is attached to the nanocellulose as a result of reaction of the saturated monocarboxylic acid with the nanocellulose.

[0094] Saturated monocarboxylic acids include, for example, formic acid, acetic acid, propionic acid, and butyric acid.

[0095] [Active Energy Ray-Curable Monomer] The active energy ray-curable composition according to this embodiment contains an active energy ray-curable monomer. The active energy ray-curable monomer may be any monomer that can be cured by irradiation with active energy rays.

[0096] The active energy ray-curable monomer is preferably a compound having an ethylenically unsaturated group, such as a (meth)acryloyl group, a vinyl group, or a vinyl ether group.

[0097] The compound having an ethylenically unsaturated group may further have a hydrogen-bonding group in addition to the ethylenically unsaturated group. Examples of the hydrogen-bonding group include a hydroxyl group, a carboxyl group, an amide group, a carbamate group, an imide group, and a urea group.

[0098] (Compound Having a Hydroxyl Group and an Ethylenically Unsaturated Group) Examples of the compound having a hydroxyl group and an ethylenically unsaturated group include hydroxyl group-containing (meth)acrylates.

[0099] Examples of hydroxyl group-containing (meth)acrylates include the following compounds (note that in compounds where the position of the hydroxy group is not specified, the substitution position of the hydroxy group is arbitrary).

[0100] Hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxypentyl (meth)acrylate, hydroxyhexyl (meth)acrylate, and hydroxyoctyl (meth)acrylate.

[0101] Glycol mono(meth)acrylates such as ethylene glycol mono(meth)acrylate, propylene glycol mono(meth)acrylate, butanediol mono(meth)acrylate, pentanediol mono(meth)acrylate, and hexanediol mono(meth)acrylate.

[0102] Polyalkylene glycol mono(meth)acrylates such as diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, dipropylene glycol mono(meth)acrylate, tripropylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, and polypropylene glycol mono(meth)acrylate.

[0103] Polyol mono(meth)acrylates such as trimethylolpropane mono(meth)acrylate, glycerin mono(meth)acrylate, pentaerythritol mono(meth)acrylate, ditrimethylolpropane mono(meth)acrylate, and dipentaerythritol mono(meth)acrylate.

[0104] (Compound Having a Carboxy Group and an Ethylenically Unsaturated Group) Examples of the compound having a carboxy group and an ethylenically unsaturated group include carboxy group-containing (meth)acrylates.

[0105] Examples of the carboxy group-containing (meth)acrylate include (meth)acrylic acid, polycaprolactone-modified (meth)acrylic acid, Michael addition type polymers of (meth)acrylic acid, adducts of 2-hydroxyethyl (meth)acrylate and phthalic anhydride, and adducts of 2-hydroxyethyl (meth)acrylate and succinic anhydride.

[0106] (Compound Having an Amide Group and an Ethylenically Unsaturated Group) Examples of the compound having an amide group and an ethylenically unsaturated group include N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, and (meth)acrylamide compounds.

[0107] Examples of the (meth)acrylamide-based compound include the following compounds:

[0108] N-alkylacrylamides such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and Nt-butyl(meth)acrylamide.

[0109] N,N-dialkylacrylamides such as N,N-dimethyl(meth)acrylamide and N,N-diethyl(meth)acrylamide.

[0110] N-hydroxyalkyl(meth)acrylamides such as N-hydroxyethyl(meth)acrylamide and N-methylol(meth)acrylamide.

[0111] N-alkoxyalkyl(meth)acrylamides such as N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, and N-methoxyethyl(meth)acrylamide.

[0112] (Meth)acryloylmorpholine.

[0113] (Compound Having a Carbamate Group and an Ethylenically Unsaturated Group) Examples of the compound having a carbamate group and an ethylenically unsaturated group include (meth)acrylates having an oxazolidone group.

[0114] An example of a (meth)acrylate having an oxazolidone group is 2-(2-oxo-3-oxazolidinyl)ethyl (meth)acrylate.

[0115] (Compound Having an Imide Group and an Ethylenically Unsaturated Group) Examples of the compound having an imide group and an ethylenically unsaturated group include a compound having a maleimide group.

[0116] Examples of compounds having a maleimide group include (meth)acrylates having a hexahydrophthalimide group and (meth)acrylates having a tetrahydrophthalimide group.

[0117] An example of a (meth)acrylate having a hexahydrophthalimide group is N-(meth)acryloyloxyethylhexahydrophthalimide.

[0118] An example of a (meth)acrylate having a tetrahydrophthalimide group is N-(meth)acryloyloxyethyltetrahydrophthalimide.

[0119] (Urethane (meth)acrylate) The active energy ray-curable monomer may be a compound having two or more ethylenically unsaturated groups. Examples of such compounds include a compound having a urethane bond and two or more (meth)acryloyl groups (hereinafter also referred to as "urethane (meth)acrylate").

[0120] Examples of urethane (meth)acrylates include reaction products of polyol, organic polyisocyanate, and hydroxyl group-containing (meth)acrylate; and reaction products of organic polyisocyanate and hydroxyl group-containing (meth)acrylate.

[0121] {Polyol} Examples of polyols include low-molecular-weight diols, diols having a polyester skeleton, diols having a polyether skeleton, and diols having a polycarbonate skeleton.

[0122] Low molecular weight diols include, for example, ethylene glycol, propylene glycol, cyclohexanedimethanol, neopentyl glycol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol.

[0123] Examples of diols having a polyester skeleton include esterification products of diol components (e.g., the low-molecular-weight diols or polycaprolactone diols) with acid components (e.g., dicarboxylic acids or their anhydrides). Examples of dicarboxylic acids or their anhydrides include adipic acid, succinic acid, phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, and terephthalic acid, as well as their anhydrides.

[0124] Examples of diols having a polyether skeleton include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

[0125] Examples of diols having a polycarbonate skeleton include reaction products of diol components (such as the low-molecular-weight diols or bisphenols) with dialkyl carbonates (such as ethylene carbonate and dibutyl carbonate).

[0126] {Organic Polyisocyanate} Examples of organic polyisocyanates include aliphatic polyisocyanates having no alicyclic group (hereinafter also referred to as "aliphatic polyisocyanates"), aliphatic polyisocyanates having an alicyclic group (hereinafter also referred to as "alicyclic polyisocyanates"), polyisocyanates having a heterocycle, and aromatic polyisocyanates.

[0127] Aliphatic polyisocyanates include, for example, hexamethylene diisocyanate, tetramethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate.

[0128] Examples of alicyclic polyisocyanates include hydrogenated tolylene diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, hydrogenated xylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, and isophorone diisocyanate trimer.

[0129] An example of the polyisocyanate having a heterocycle is hexamethylene diisocyanate trimer.

[0130] Examples of aromatic polyisocyanates include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, paraphenylene diisocyanate, and 1,5-naphthalene diisocyanate.

[0131] {Hydroxyl Group-Containing (Meth)acrylate} Examples of the hydroxyl group-containing (meth)acrylate include the compounds exemplified above in the section "(Compound having a hydroxyl group and an ethylenically unsaturated group)."

[0132] Furthermore, as the hydroxyl group-containing (meth)acrylate, a compound having a hydroxyl group and two or more (meth)acryloyl groups (hereinafter also referred to as "hydroxyl group-containing polyfunctional (meth)acrylate") may be used.

[0133] Examples of the hydroxyl group-containing polyfunctional (meth)acrylate include glycerin di(meth)acrylate, alkylene oxide-modified isocyanuric acid di(meth)acrylate, trimethylolpropane di(meth)acrylate, di- or tri(meth)acrylate of pentaerythritol, di- or tri(meth)acrylate of ditrimethylolpropane, and di-, tri-, tetra-, or penta(meth)acrylate of dipentaerythritol. Examples of the alkylene oxide-modified compound in this specification include ethylene oxide-modified compounds, propylene oxide-modified compounds, and compounds modified with ethylene oxide and propylene oxide.

[0134] (Polyester (meth)acrylate) Examples of the polyester (meth)acrylate include a dehydration condensation product of a polyester diol and (meth)acrylic acid. Examples of the polyester diol include a reaction product of a polyhydric alcohol (e.g., a diol) and a polycarboxylic acid (e.g., a dicarboxylic acid) or an anhydride thereof.

[0135] {Diol} Examples of diols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, butylene glycol, polybutylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, cyclohexanedimethanol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol, as well as alkylene oxide adducts thereof.

[0136] {Dicarboxylic Acid} Examples of dicarboxylic acids or anhydrides thereof include orthophthalic acid, isophthalic acid, terephthalic acid, adipic acid, succinic acid, fumaric acid, maleic acid, hexahydrophthalic acid, tetrahydrophthalic acid, and trimellitic acid, and anhydrides thereof.

[0137] (Epoxy (meth)acrylate) Examples of the epoxy (meth)acrylate include compounds obtained by addition reaction of an epoxy resin with (meth)acrylic acid. Examples of the epoxy resin include aromatic epoxy resins and aliphatic epoxy resins.

[0138] {Aromatic Epoxy Resin} Examples of aromatic epoxy resins include resorcinol diglycidyl ether, hydroquinone diglycidyl ether; diglycidyl ethers of bisphenol A, bisphenol F, bisphenol S, bisphenol fluorene, or alkylene oxide adducts thereof; novolac epoxy resins such as phenol novolac epoxy resins and cresol novolac epoxy resins; glycidyl phthalimide; and o-phthalic acid diglycidyl ester.

[0139] {Aliphatic Epoxy Resin} Examples of aliphatic epoxy resins include diglycidyl ethers of alkylene glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, and 1,6-hexanediol; diglycidyl ethers of polyalkylene glycols such as diglycidyl ethers of polyethylene glycol and polypropylene glycol; diglycidyl ethers of neopentyl glycol, dibromoneopentyl glycol, and alkylene oxide adducts thereof; diglycidyl ethers of hydrogenated bisphenol A and alkylene oxide adducts thereof; and tetrahydrophthalic acid diglycidyl ester.

[0140] (Other Compounds) Examples of other compounds having an ethylenically unsaturated group include the following compounds.

[0141] Alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate.

[0142] (meth)acrylates having an alicyclic group, such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, and 1-adamantyl (meth)acrylate.

[0143] Alkoxyalkyl (meth)acrylates such as 2-methoxyethyl (meth)acrylate and 2-ethoxyethoxyethyl (meth)acrylate.

[0144] (Meth)acrylates having a heterocycle, such as tetrahydrofurfuryl (meth)acrylate and glycerin carbonate (meth)acrylate.

[0145] (Meth)acrylates having an aromatic ring, such as phenyl (meth)acrylate, o-phenylphenyl (meth)acrylate, p-cumylphenyl (meth)acrylate, benzyl (meth)acrylate, (meth)acrylates of phenol alkylene oxide adducts, (meth)acrylates of p-cumylphenol alkylene oxide adducts, (meth)acrylates of o-phenylphenol alkylene oxide adducts, and (meth)acrylates of nonylphenol alkylene oxide adducts.

[0146] (Meth)acrylates such as glycidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and allyl (meth)acrylate.

[0147] Bifunctional (meth)acrylates having an aromatic skeleton, such as di(meth)acrylate of bisphenol A alkylene oxide adduct, bisphenol A di(meth)acrylate, and di(meth)acrylate of bisphenol F alkylene oxide adduct.

[0148] Bifunctional (meth)acrylates having an aliphatic skeleton, such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, polybutylene glycol di(meth)acrylate, poly(1-methylbutylene glycol) di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, and neopentyl glycol di(meth)acrylate.

[0149] Hydroxypivalic acid neopentyl glycol di(meth)acrylate, and hydroxypivalic acid neopentyl glycol ε-caprolactone-modified di(meth)acrylate.

[0150] Bifunctional (meth)acrylates having an alicyclic skeleton, such as dimethyloltricyclodecane di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, and spiroglycol di(meth)acrylate.

[0151] 2-ethylhexyl alkylene oxide-modified (meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane alkylene oxide-modified tri(meth)acrylate, isocyanuric acid alkylene oxide-modified tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, diglycerin alkylene oxide-modified (meth)acrylate, ω-carboxy-polycaprolactone mono(meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate.

[0152] The active energy ray-curable monomer may be one type or a plurality of types.

[0153] The active energy ray-curable monomer is preferably hydrophobic, and more preferably water-insoluble or water-immiscible. "Water-insoluble" means that when the active energy ray-curable monomer is solid, the amount that dissolves in 100 g of water at 25°C is 5 g or less. "Water-immiscible" means that when the active energy ray-curable monomer is liquid, it does not mix with water at 25°C.

[0154] The amount of water-insoluble active energy ray-curable monomer that dissolves in 100 g of water at 25° C. may be 4 g or less, 3 g or less, 2 g or less, 1 g or less, or 0.5 g or less.

[0155] [Photopolymerization initiator] The active energy ray-curable composition according to this embodiment may further contain a photopolymerization initiator. Note that, when the active energy ray-curable composition is cured with an electron beam, for example, the photopolymerization initiator may not be contained.

[0156] Examples of the photopolymerization initiator include the following compounds:

[0157] Benzyl dimethyl ketal, benzil, benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 1-hydroxycyclohexyl phenyl ketone (manufactured by IGM Resins B.V., Omnirad 184D), 2-hydroxy-2-methyl-1-phenylpropan-1-one (manufactured by IGM Resins B.V., Omnirad 1173), 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one (manufactured by IGM Resins B.V., Omnirad 1174), B.V., Omnirad 2959), oligo[2-hydroxy-2-methyl-1-[4-1-(methylvinyl)phenyl]propanone, 2-hydroxy-1-[4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl]-2-methylpropan-1-one (IGM Resins B.V., Omnirad 127), 2-methyl-1-[4-(methylthio)]phenyl]-2-morpholinopropan-1-one (IGM Resins B.V., Omnirad 907), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one (IGM Resins B.V., Omnirad 127), aromatic ketone compounds such as 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one (Omnirad 379, manufactured by IGM Resins B.V.);

[0158] Benzophenone-based compounds such as benzophenone, 2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 4-(methylphenylthio)phenylphenylmethane, methyl-2-benzophenone, 1-[4-(4-benzoylphenylsulfanyl)phenyl]-2-methyl-2-(4-methylphenylsulfonyl)propan-1-one, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, N,N'-tetramethyl-4,4'-diaminobenzophenone, N,N'-tetraethyl-4,4'-diaminobenzophenone, and 4-methoxy-4'-dimethylaminobenzophenone.

[0159] Acylphosphine oxide compounds such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl-(2,4,6-trimethylbenzoyl)phenylphosphineate, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide.

[0160] Thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 1-chloro-4-propylthioxanthone, 3-[3,4-dimethyl-9-oxo-9H-thioxanthone-2-yl]oxy]-2-hydroxypropyl-N,N,N-trimethylammonium chloride, and fluorothioxanthone.

[0161] Acridone and acridone-based compounds such as 10-butyl-2-chloroacridone.

[0162] Oxime esters such as 1,2-octanedione 1-[4-(phenylthio)-2-(O-benzoyloxime)], and ethanone 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime).

[0163] 2,4,5-triarylimidazole dimers such as 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-di(m-methoxyphenyl)imidazole dimer, 2-(o-fluorophenyl)-4,5-phenylimidazole dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer, 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer, 2,4-di(p-methoxyphenyl)-5-phenylimidazole dimer, and 2-(2,4-dimethoxyphenyl)-4,5-diphenylimidazole dimer.

[0164] Acridine derivatives such as 9-phenylacridine and 1,7-bis(9,9'-acridinyl)heptane.

[0165] Adeka Optomer N-1414 (manufactured by ADEKA Corporation), phenylglyoxylic acid methyl ester, ethyl anthraquinone, and phenanthrenequinone.

[0166] The amount of the photopolymerization initiator is preferably 0.05 to 20.0% by mass, more preferably 0.3 to 15.0% by mass, and even more preferably 0.5 to 10.0% by mass, based on the mass of the active energy ray-curable monomer.

[0167] [Other Components] The active energy ray-curable composition according to this embodiment may contain, for example, a solvent, a dispersion medium, an antifoaming agent, a thickener, a pigment, a pH adjuster, a crosslinking agent, a plasticizer, a stabilizer, a preservative, an antioxidant, a light stabilizer, or an ultraviolet absorber.

[0168] <Method for Producing a Cured Product> One embodiment of the present invention relates to a method for producing a cured product, which includes a step of irradiating the above-described active energy ray-curable composition with active energy rays to cure the composition.

[0169] Examples of active energy rays include ultraviolet rays, visible light, and electron beams.

[0170] When ultraviolet light is selected as the active energy ray, an ultraviolet light irradiation device can be used. Examples of light sources in the ultraviolet light irradiation device include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a black light lamp, a UV electrodeless lamp, and an LED.

[0171] The conditions for irradiation with active energy rays may be adjusted as appropriate depending on, for example, the components of the active energy ray-curable composition or the application of the cured product.

[0172] <Cured Product> One embodiment of the present invention relates to a cured product obtained by curing the above-described active energy ray-curable composition.

[0173] Examples of uses of the active energy ray-curable composition or a cured product thereof include molding resins that utilize polymerization or crosslinking reactions, casting resins, resins for stereolithography, sealants, dental polymerized resins, printing inks, printing varnishes, paints, photosensitive resins for printing plates, color proofs for printing, color filter resists, black matrix resists, photospacers for liquid crystal displays, rear projection screen materials, optical fibers, rib materials for plasma displays, dry film resists, resists for printed circuit boards, solder resists, photoresists for semiconductors, resists for microelectronics, resists for manufacturing micromachine parts, etching resists, microlens arrays, insulating materials, hologram materials, optical switches, waveguide materials, overcoating agents, powder coatings, adhesives, pressure-sensitive adhesives, release agents, optical recording media, pressure-sensitive adhesives, release coating agents, compositions for image recording materials using microcapsules, and various devices.

[0174] 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 to these.

[0175] Various values ​​in the examples may be used as preferred lower or upper limits in the embodiments of the present invention. Two values ​​of the same type in the examples may be appropriately combined to form a preferred range of values.

[0176] <Measurement of various properties> [Carboxy group amount of oxidized cellulose] To 100 mL of an aqueous cellulose dispersion in which the concentration of oxidized cellulose obtained in the following Production Example had been adjusted to 0.1% by mass, 0.1 M aqueous hydrochloric acid was added to adjust the pH to 2.5, and then 0.05 N aqueous sodium hydroxide solution was added dropwise, and the electrical conductivity was measured until the pH reached 11.0. The amount of carboxy groups (mmol / g) was calculated using the following formula from the amount of sodium hydroxide (a) consumed in the neutralization stage of the weak acid, where the change in electrical conductivity was gradual: Amount of carboxy groups = a (mL) × 0.05 / mass of cellulose (g).

[0177] [Degree of modification (degree of substitution) 1 of modified nanocellulose] The degree of modification (degree of substitution) of the methacrylic acid-modified and acetic acid-modified (acetylated) nanocellulose obtained in Production Example 1 below was measured as follows.

[0178] 0.05 g of the modified nanocellulose obtained in Production Example 1 below was precisely weighed, and 1.5 ml of ethanol and 0.5 ml of distilled water were added to it. This was left to stand in a water bath at 60-70 ° C for 30 minutes, and then 2 ml of 0.5 M aqueous sodium hydroxide solution was added. This was left to stand in a water bath at 60-70 ° C for 3 hours, and then ultrasonically shaken for 30 minutes in an ultrasonic cleaner. This was titrated with a 0.1 M hydrochloric acid standard solution using phenolphthalein as an indicator.

[0179] The amount Z (ml) of 0.1 M hydrochloric acid solution required for the titration, and the amount Z (ml) of 0.1 N hydrochloric acid solution required for the titration of the blank sample (= sample without modified nanocellulose) ０ From the total amount (ml) of carboxyl groups and modifying groups, Q (mol) was calculated using the following formula: Q (mol) = (Z ０ -Z)×0.1 / 1000

[0180] The mass of the modified nanocellulose (=0.05 g precisely weighed value, symbolized as A) is the mass of the unmodified glucopyranose ring structure (C ６ H １０ O ５ , Mw=162) and the mass of the glucopyranose structure (C ６ H ８ O ７ A(g) can be considered as the sum of the mass of the modified glucopyranose structure (Mw=145+T (T is the molecular weight of the modifying group)) and the mass of the modified glucopyranose structure (Mw=145+T (T is the molecular weight of the modifying group)). If the number of moles of each structure is x, y, and z (mol), the following formula 1 is established: A(g)=162×x+192×y+(145+T)×z...Formula 1

[0181] The Q (mol) previously determined by titration satisfies the following formula 2: Q (mol) = 2y + z... formula 2

[0182] The amount of carboxy groups in cellulose (mmol / g, symbolized as B) determined by the method described in the [Amount of Carboxy Groups] column can be converted to y using the following formula 3: y (mol) = B (mmol / g) × A (g) / 1000 × 1 / 2 ... formula 3

[0183] Here, the degree of substitution is the value obtained by dividing the number of moles of the introduced modifying group by the total number of moles of glucopyranose rings, and can be calculated using the following formula 4: Degree of substitution (dimensionless number) = z / (x + y + z) Formula 4

[0184] Using Equations 1 to 4 and organizing them into A, B, Q, and T, the degree of substitution can be calculated using the following Equation 5. The degree of substitution of the modified nanocellulose was calculated from Equation 5.

[0185] [Degree of modification (degree of substitution) 2 of modified nanocellulose] The degree of modification (degree of substitution) of the maleic acid-modified nanocellulose and itacon-modified nanocellulose obtained in Production Examples 2 and 3 below was measured as follows.

[0186] To 100 ml of the modified nanocellulose aqueous dispersion obtained in Production Example 2 or 3 below, in which the concentration of modified nanocellulose was adjusted to 0.1% by mass, 0.1 M aqueous hydrochloric acid was added to adjust the pH to 2.7, and then 0.05 N aqueous sodium hydroxide solution was added dropwise and the electrical conductivity was measured until the pH reached 11.0. The amount of carboxyl groups (mmol / g) was calculated using the following formula from the amount of sodium hydroxide (a) consumed in the neutralization stage of the weak acid, in which the change in electrical conductivity was gradual. Amount of carboxyl groups = a (ml) × 0.05 / mass (g) of modified nanocellulose

[0187] The degree of substitution was calculated from the amount of carboxyl groups in the modified nanocellulose using the following formula.

[0188] <Production of modified nanocellulose> [Production Example 1: Methacrylic acid-modified and acetic acid-modified (acetylated) nanocellulose] (Oxidation process) 500 g of sodium hypochlorite aqueous solution having a pH of 12.7 and an effective chlorine concentration of 12.5% ​​by mass was placed in a jacketed glass container, and stirred at 200 rpm using a three-piece swept-back blade in a Shinto Scientific agitator (Three-One Motor, BL600). After heating to 35 ° C., 47 g of powdered pulp (KC Flock W-100GK) from Nippon Paper Industries Co., Ltd. was added as a cellulosic raw material. After supplying the cellulosic raw material, the mixture was stirred until the pH dropped to 10.5 while keeping the temperature at 35 ° C., and then the pH during the reaction was maintained at 10.5 while adding a 25% by mass aqueous sodium hydroxide solution. The mixture was stirred for a total of 520 minutes under the same conditions after the cellulosic raw material was added.

[0189] After the reaction was completed, the remaining sodium hypochlorite was inactivated by adding an aqueous hydrogen peroxide solution, and then hydrochloric acid was added to convert the carboxyl groups of the oxidized cellulose from the salt form (-COO-Na) to the proton form (-COO-H), yielding an aqueous dispersion with a pH of 2.5. The solid-liquid dispersion was separated by pressure filtration at 0.2 MPa and then washed with an aqueous hydrochloric acid solution at a pH of 2.5.

[0190] Sodium hydroxide was added to the resulting proton-type oxidized cellulose to convert the carboxylic acid groups from the proton type (—COO—H) back to the salt type (—COO—Na), yielding an aqueous dispersion of Na-type oxidized cellulose with a pH of 7.4.

[0191] The amount of carboxy groups in the oxidized cellulose was measured to be 0.78 mmol / g. The nitrogen content derived from N-oxyl compounds in the oxidized cellulose was measured as the nitrogen amount using a total nitrogen trace analyzer (TN-2100H, manufactured by Nitto Seiko Analytech Co., Ltd.), and the increase from the raw pulp was calculated to be less than 1 ppm.

[0192] (Defibrillation process) The Na-type oxidized cellulose aqueous dispersion (solid content 7.5% by mass) was treated with a homomixer (Primix, Robomix) at 10,000 rpm with 440 g of liquid for 33 minutes to defibrate the oxidized cellulose into nanocellulose, obtaining a nanocellulose aqueous dispersion. A 1N aqueous hydrochloric acid solution was added to the resulting aqueous dispersion to adjust the pH to 2.0-2.1, and then the dispersion was washed twice with pure water using a tabletop multi-rack centrifuge (KOKUSAN, H-40α). The mixture was then washed (substituted) four times with acetone in the same manner, and then concentrated by suction filtration using a vacuum pump to obtain acetone-substituted H-type nanocellulose.

[0193] (Modification step) To 1 part by mass of H-type nanocellulose, 1.5 parts by mass of methacrylic anhydride, 0.05 parts by mass of 70% perchloric acid, 8.8 parts by mass of acetone, and 8 parts by mass of toluene were added and stirred for 1 hour at 50 ° C. Methanol was added to the reaction solution, stirred, and the reaction was stopped. After that, a tabletop multi-rack centrifuge (H-40α, manufactured by KOKUSAN) was used to wash (replace) with methanol seven times to obtain methacrylic acid-modified H-type nanocellulose.

[0194] To 1 part by mass of methacrylic acid-modified H-type nanocellulose, 1.1 parts by mass of acetic anhydride, 0.05 parts by mass of 70% perchloric acid, 6 parts by mass of acetone, and 14.4 parts by mass of toluene were added and stirred at room temperature for 1 hour. Methanol was added to the reaction solution, stirred, and the reaction was stopped. After that, a tabletop multi-rack centrifuge (KOKUSAN, H-40α) was used. Washing (replacement) with methanol seven times was performed to obtain methacrylic acid-modified and acetylated H-type nanocellulose.

[0195] When the degree of substitution of the modified nanocellulose was measured, the degree of substitution with methacrylic acid was 0.4 and the degree of substitution with acetic acid was 0.8.

[0196] [Production Example 2: Maleic Acid Modified Nanocellulose] To the acetone-substituted H-type nanocellulose obtained in the defibration step of Production Example 1, JEFFAMINE M-2005 (manufactured by Tomoe Engineering Co., Ltd.) in an amount equivalent to the acid value was added and stirred. Toluene was added to this and the solids concentration was adjusted to 5% by mass. The residue was removed by filtration using a filter cloth, and the acetone was distilled off using an evaporator to obtain a toluene dispersion of organic ammonium salt-type nanocellulose.

[0197] To 1 part by mass of organic ammonium salt-type nanocellulose, 20 parts by mass of maleic anhydride and 42 parts by mass of toluene were added, and the mixture was stirred for 1.5 hours at 90 ° C. Methanol was added to the reaction solution, stirred, and the reaction was stopped. After that, the mixture was washed (substituted) with methanol seven times using a tabletop multi-rack centrifuge (KOKUSAN, H-40α) to obtain maleic acid-modified H-type nanocellulose.

[0198] When the degree of substitution of the modified nanocellulose was measured, the degree of substitution with maleic acid was 0.2.

[0199] [Production Example 3: Itaconic acid-modified nanocellulose] Itaconic acid-modified H-type nanocellulose was obtained in the same manner as in Production Example 2, except that the maleic anhydride in Production Example 2 was changed to itaconic anhydride and the number of parts by mass of toluene was changed to 71 parts by mass.

[0200] When the degree of substitution of the modified nanocellulose was measured, the degree of substitution with itaconic acid was 0.2.

[0201] <Production of Active Energy Ray-Curable Composition and Cured Product> [Example 1] The acetone dispersion (solid content 1.0% by mass) of methacrylic acid-modified and acetylated nanocellulose produced in Production Example 1 and Aronix M-113 (manufactured by Toagosei Co., Ltd.) were mixed and stirred for 10 minutes or more. The solvent was distilled off using an evaporator to reduce the amount of solvent to 8% by mass or less. 3 parts by mass of a photopolymerization initiator (Omnirad 184, manufactured by IBM Resins B.V.) was added to 100 parts by mass of this mixture to produce an active energy ray-curable composition. The obtained composition was poured into a 1 mm thick mold sandwiched between PET films. Using a conveyor-type ultraviolet irradiation device (US5-X0602, manufactured by iGraphics Co., Ltd.), an integrated illuminance of 5000 mW / cm was obtained. ２ The composition was cured by UV irradiation to obtain a sheet-like cured product. The amount of modified nanocellulose (not the dispersion liquid, but the modified nanocellulose itself) in this example was 2% by mass based on the mass of M-113.

[0202] [Example 2] A cured product was obtained in the same manner as in Example 1, except that the modified nanocellulose in Example 1 was changed to the maleic acid-modified nanocellulose produced in Production Example 2.

[0203] [Example 3] A cured product was obtained in the same manner as in Example 1, except that the modified nanocellulose in Example 1 was changed to the itaconic acid-modified nanocellulose produced in Production Example 3.

[0204] [Example 4] A cured product was obtained in the same manner as in Example 1, except that the amount of modified nanocellulose in Example 1 was changed from 2% by mass to 1% by mass.

[0205] Comparative Example 1 A cured product was obtained in the same manner as in Example 1, except that the modified nanocellulose in Example 1 was not used. The composition of Comparative Example 1 corresponds to the target composition for Examples 1 to 4, and the cured product of Comparative Example 1 corresponds to the target cured product. The breaking elongation ratio, maximum stress ratio, elastic modulus ratio, and breaking work ratio in Table 1 were calculated from the ratios of the breaking elongation, maximum stress, elastic modulus, and breaking work of the example to the breaking elongation, maximum stress, elastic modulus, and breaking work of the example, respectively, relative to the breaking elongation, maximum stress, elastic modulus, and breaking work of the example in Comparative Example 1.

[0206] [Comparative Example 2] An active energy ray-curable composition was produced in the same manner as in Example 1, except that the modified nanocellulose in Example 1 was replaced with the unmodified nanocellulose (obtained in the [defibration step]) produced in Production Example 1. Since the unmodified nanocellulose did not disperse in Aronix M-113, the cured product, as described below, was not evaluated.

[0207] Evaluation of Cured Products: From the sheet-like cured products obtained in the above Examples and Comparative Examples, rectangular test pieces (thickness: approximately 1 mm) with a total length of 50 mm and a gauge width of 5 mm were cut out. These test pieces were subjected to tensile tests in accordance with JIS K6251 using a tensile tester (INSTRON, INSTRON 5566A) at 23±2°C, a gauge length of 10 mm, and a tensile speed of 100 mm / min. The tensile tests measured the elongation at break (%), maximum stress (kPa), modulus of elasticity (kPa), and work at fracture (mJ). The results are shown in Table 1 and FIG. 1.

[0208]

[0209] As can be seen from a comparison between Examples 1 to 4 and Comparative Example 1, the maximum stress was improved by using modified nanocellulose. As can be seen from a comparison between Example 1 and Example 2 or 3, the maximum stress was significantly improved by using modified nanocellulose into which a modifying group having a double bond and no carboxy group was introduced.

Claims

1. An active energy ray-curable composition comprising: modified nanocellulose; and an active energy ray-curable monomer, wherein the modified nanocellulose comprises: nanocellulose; and a modifying group introduced into the nanocellulose, wherein the modifying group is introduced via a covalent bond to at least some of the hydroxyl groups of the nanocellulose, and the modifying group has a carbon-carbon unsaturated bond.

2. The active energy ray-curable composition according to claim 1, wherein the nanocellulose has a structure in which the hydroxyl groups at the second and third positions of the glucopyranose ring are oxidized to introduce dicarboxyl groups.

3. The active energy ray-curable composition according to claim 1, wherein the nanocellulose contains an oxide of a cellulose-based raw material with hypochlorous acid or a salt thereof, and is substantially free of N-oxyl compounds.

4. The active energy ray-curable composition according to claim 1, wherein the ratio of the breaking elongation of a cured product obtained by curing the active energy ray-curable composition to the breaking elongation of a control cured product obtained by curing a control composition in which the modified nanocellulose is omitted from the active energy ray-curable composition is 0.60 or more.

5. The active energy ray-curable composition according to claim 1, wherein the ratio of the maximum stress value of a cured product obtained by curing the active energy ray-curable composition to the maximum stress value of a control cured product obtained by curing a control composition in which the modified nanocellulose is omitted from the active energy ray-curable composition is 2.0 or more.

6. The active energy ray-curable composition according to claim 1, wherein the ratio of the modulus of elasticity of a cured product obtained by curing the active energy ray-curable composition to the modulus of elasticity of a control cured product obtained by curing a control composition in which the modified nanocellulose is omitted from the active energy ray-curable composition is 1.1 or more.

7. The active energy ray-curable composition according to claim 1, wherein the ratio of the work of fracture of a cured product obtained by curing the active energy ray-curable composition to the work of fracture of a control cured product obtained by curing a control composition in which the modified nanocellulose is omitted from the active energy ray-curable composition is 1.5 or more.

8. The hydroxyl group to which the modifying group has been introduced is represented by the following formula (1): R １ -C(=O)-O- (1) [R １ The active energy ray-curable composition according to claim 1 , wherein R is a substituted or unsubstituted alkenyl group, or a substituted or unsubstituted cycloalkenyl group.

9. R １ The active energy ray-curable composition according to claim 8 , wherein is an unsubstituted alkenyl group.

10. The active energy ray-curable composition according to claim 1, wherein the modifying group is derived from at least one compound selected from the group consisting of monocarboxylic acid compounds having a carbon-carbon unsaturated bond and dicarboxylic acid compounds having a carbon-carbon unsaturated bond.

11. The active energy ray-curable composition according to claim 10, wherein the modifying group is derived from a monocarboxylic acid compound having a carbon-carbon unsaturated bond, and the monocarboxylic acid compound contains (meth)acrylic acid.

12. The active energy ray-curable composition according to claim 10, wherein the modifying group is derived from a dicarboxylic acid compound having a carbon-carbon unsaturated bond, and the dicarboxylic acid compound includes maleic acid and / or itaconic acid.

13. The active energy ray-curable composition according to claim 1, wherein the average fiber width of the modified nanocellulose is 1 to 50 nm.

14. The active energy ray-curable composition according to claim 1, wherein the average fiber length of the modified nanocellulose is 50 to 3,000 nm.

15. The active energy ray-curable composition according to claim 1, further comprising a photopolymerization initiator.

16. A cured product of the active energy ray-curable composition according to any one of claims 1 to 15.

17. A method for producing a cured product, comprising the step of irradiating the active energy ray-curable composition according to any one of claims 1 to 15 with active energy rays to cure the composition.

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