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

Abstract

The purpose of the present invention is to provide an active energy ray-curable composition with which a cured product that can have both flexibility and pencil hardness can be formed. This active energy ray-curable composition comprises modified nanocellulose and an active energy ray-curable monomer. The modified nanocellulose includes nanocellulose and a modifying group introduced into the nanocellulose. The modified nanocellulose has a structure (i) and / or a structure (ii): (i) a structure in which the modifying group is introduced into at least some of hydroxyl groups in the nanocellulose via a covalent bond; and (ii) a structure in which the modifying group is introduced into at least some of carboxy groups in the nanocellulose via an ionic bond. The active energy ray-curable monomer includes a polyfunctional monomer.

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 that has both good flexibility and pencil hardness.

[0008] As a result of extensive research, the inventors have discovered that by combining modified nanocellulose with an active energy ray-curable monomer, it is possible to form a cured product that has both flexibility and pencil hardness.

[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, and the modified nanocellulose has the following structure (i) and / or (ii): (i) a structure in which the modifying group is introduced to at least some of the hydroxyl groups of the nanocellulose via a covalent bond; (ii) a structure in which the modifying group is introduced to at least some of the carboxyl groups of the nanocellulose via an ionic bond; and the active energy ray-curable monomer comprises a polyfunctional monomer. [2] An active energy ray-curable composition comprising: a 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 modified nanocellulose has the following structure (i) and / or (ii): (i) a structure in which the modifying group is introduced to at least some of the hydroxyl groups of the nanocellulose via a covalent bond; (ii) a structure in which the modifying group is introduced to at least some of the carboxyl groups of the nanocellulose via an ionic bond; When the active energy ray-curable composition is cured in air or under a nitrogen atmosphere, in a mandrel test of the cured product, the minimum diameter of the mandrel that does not crack the cured product is 10 mm or less, and the pencil hardness of the cured product is the same as or at least one level higher than that of a cured product that does not contain nanocellulose.[3] An active energy ray-curable composition comprising: a 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 modified nanocellulose has the following structure (i) and / or (ii): (i) a structure in which the modifying group is introduced to at least some of the hydroxyl groups of the nanocellulose via a covalent bond; (ii) a structure in which the modifying group is introduced to at least some of the carboxyl groups of the nanocellulose via an ionic bond; and the active energy ray-curable monomer is a monomer that, when the active energy ray-curable monomer is cured in air or under a nitrogen atmosphere, results in a storage modulus of the cured product at 25°C of 0.5 x 10^8 Pa or more. [4] An active energy ray-curable composition comprising: a 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 modified nanocellulose has the following structure (i) and / or (ii): (i) a structure in which the modifying group is introduced via a covalent bond to at least some of the hydroxyl groups of the nanocellulose; (ii) a structure in which the modifying group is introduced via an ionic bond to at least some of the carboxyl groups of the nanocellulose; The active energy ray-curable monomer is a monomer that, when the active energy ray-curable monomer is cured in air or under a nitrogen atmosphere, results in a cured product with an indentation modulus at 30°C of 0.5 x 10^8 Pa or more. [5] The active energy ray-curable composition according to claim 3, wherein the cured product has a storage modulus at 25°C of 2.0 x 10^8 Pa or more. [6] The modified nanocellulose has the structure (i), and the hydroxyl group into which the modifying group has been introduced is represented by the following formula (1): R-C(=O)-O- (1) [R is a substituted or unsubstituted alkyl group, or a substituted or unsubstituted cycloalkyl group]. The active energy ray-curable composition according to any one of [1] to [5].[7] The active energy ray-curable composition according to any one of [1] to [6], wherein the modified nanocellulose has the structure (i) and the modifying group is an acetyl group. [8] The active energy ray-curable composition according to any one of [1] to [7], 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. [9] The active energy ray-curable composition according to any one of [1] to [8], 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 dicarboxy groups.

[10] The active energy ray-curable composition according to any one of [1] to [9], wherein the modified nanocellulose has an average fiber width of 1 to 10 nm.

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

[10] , wherein the modified nanocellulose has an average fiber length of 10 to 800 nm.

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

[11] , further comprising a photopolymerization initiator.

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

[12] .

[14] The cured product according to

[13] , wherein the cured product is a cured film.

[15] The cured product according to

[14] , wherein in a mandrel test of the cured film, the minimum diameter of a mandrel that does not crack the cured film is 10 mm or less, and the pencil hardness of the cured film is 2H or more.

[16] A method for producing a cured product, comprising: irradiating the active energy ray-curable composition according to any one of [1] to

[12] with active energy rays to cure the composition.

[17] The production method according to

[16] , wherein the irradiation is carried out under a nitrogen atmosphere.

[0010] The present invention can provide an active energy ray-curable composition capable of forming a cured product that has both flexibility and pencil hardness.

[0011] 1 shows images of coating films obtained by carrying out a scratch resistance test on the coating films of Examples 1 and 2 and Comparative Examples 1 and 2.

[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 is an active energy ray-curable composition comprising modified nanocellulose and an active energy ray-curable monomer. The modified nanocellulose comprises nanocellulose and a modifying group introduced into the nanocellulose, and has the following structure (i) and / or (ii): (i) A structure in which the modifying group is introduced via a covalent bond to at least some of the hydroxyl groups of the nanocellulose. (ii) A structure in which the modifying group is introduced via an ionic bond to at least some of the carboxyl groups of the nanocellulose.

[0015] In one embodiment of the present invention, the active energy ray-curable monomer includes a polyfunctional monomer. This embodiment will hereinafter also be referred to as a "first embodiment."

[0016] In one embodiment of the present invention, when the active energy ray-curable composition of the present invention is cured in air or a nitrogen atmosphere, in a mandrel test of the cured product, the minimum mandrel diameter at which the cured product does not crack is 10 mm or less, and the pencil hardness of the cured product is the same as or improved by one or more levels compared to a cured product that does not contain nanocellulose. This embodiment is also referred to as the "second embodiment" below.

[0017] In one embodiment of the present invention, the active energy ray-curable monomer used in the present invention is a monomer that, when the active energy ray-curable monomer is cured in air or under a nitrogen atmosphere, gives a cured product with a storage modulus of 0.5 × 10^8 Pa or more at 25°C. This embodiment will hereinafter also be referred to as a "third embodiment".

[0018] In one embodiment of the present invention, the active energy ray-curable monomer used in the present invention is a monomer that, when the active energy ray-curable monomer is cured in air or under a nitrogen atmosphere, gives a cured product with an indentation modulus of elasticity of 0.5 × 10^8 Pa or more at 30°C. This embodiment will hereinafter also be referred to as "fourth embodiment".

[0019] Each of the first to fourth embodiments may further include features of the other embodiments. In this specification, the first to fourth embodiments are collectively referred to simply as the present embodiment. This embodiment will be described in detail below, but unless otherwise specified, various features can be applied to all of the first to fourth embodiments.

[0020] The cured product formed from the active energy ray-curable composition according to this embodiment can achieve both flexibility and pencil hardness. Furthermore, the cured product preferably has excellent scratch resistance and transparency. The reason for this is presumably that, for example, the introduction of modifying groups into at least some of the hydroxyl or carboxyl groups of nanocellulose improves the hydrophobicity of the nanocellulose, making it easier to disperse in the active energy ray-curable monomer, thereby demonstrating the flexibility, strength, and transparency of the nanocellulose. However, the present invention is not limited by these reasons.

[0021] [Properties] A cured product of the active energy ray-curable composition preferably has the following properties when formed and measured under the following conditions.

[0022] (Formation of Cured Product) Each of the active energy ray-curable composition and the control composition was applied to a 100 μm-thick PET film that had been subjected to a corona treatment using a bar coater. After sufficiently volatilizing the solvent in the coating solution as necessary, the cured product was applied to a PET film with an integrated illuminance of 5000 mW / cm. ２A coating film is formed by irradiating the coating film with UV light in air or a nitrogen atmosphere so that the thickness of the coating film is within the range of 10 μm to 20 μm, preferably 15 μm ± 3 μm. The control composition is a composition obtained by removing fillers such as 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 no fillers such as modified nanocellulose are used. The target cured product is obtained by curing the target composition.

[0023] (Measurement of cured product) The pencil hardness, scratch resistance, and flexibility of the coating film are measured. The coating film may be cut out appropriately depending on the physical properties to be measured. Preferred measurement values ​​for various properties are described below, but these values ​​may be satisfied for at least one of the film cured in air and the film cured under a nitrogen atmosphere.

[0024] (Pencil Hardness) Pencil hardness is expressed as 6B, 5B, 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H, 7H, 8H, and 9H. The pencil hardness test is measured in accordance with JIS KS5600-5-4. For example, a VF2380-13O (manufactured by Cortec) or the like can be used as the measurement device. The measurement is carried out three times (N3), and the maximum pencil hardness at which no indentation occurs is taken as the pencil hardness. Specifically, the pencil hardness test can be carried out by the method described in the examples.

[0025] In the second embodiment, the pencil hardness is the same as or is improved by one or more steps, preferably one or more steps, more preferably two or more steps, compared to a cured product that does not contain a filler such as modified nanocellulose, i.e., the target cured product.

[0026] In the active energy ray-curable composition of the second embodiment, the pencil hardness of a cured product of the composition is preferably 2H or more, more preferably 3H or more, and even more preferably 4H or more. There is no particular upper limit to the pencil hardness, and it may be, for example, 9H, 8H, 7H, or 6H.

[0027] In the second embodiment, the pencil hardness can be controlled within the above-mentioned numerical range by using modified nanocellulose as a filler, and from the viewpoint of further increasing the pencil hardness, it is preferable to use nanocellulose derived from oxidized cellulose obtained by oxidation with hypochlorous acid or a salt thereof.

[0028] (Abrasion Resistance) Steel wool (manufactured by Bonstar Sales, #0000) is pressed against the coating film at a surface pressure of 0.6 KPa and rubbed back and forth in one direction 200 times, and the degree of scratching of the sample before and after scratching is evaluated by haze measurement. Haze measurement can be performed in accordance with JIS K7136. For example, COH7700 (manufactured by Nippon Denshoku Industries Co., Ltd.) can be used for the measurement. The scratch resistance test can be specifically performed by the method described in the Examples.

[0029] The haze value of the coating film (before scratching) is preferably 5.0% or less, more preferably 4.0% or less, and even more preferably 3.0% or less. A haze value of 5.0% or less tends to result in excellent transparency. The lower limit of the haze value is ideally 0% from the viewpoint of transparency, but may be greater than 0%.

[0030] The haze value of the coating film after scratching is preferably the same as the haze value before scratching. Therefore, the haze value of the coating film after scratching is preferably 5.0% or less, more preferably 4.0% or less, and even more preferably 3.0% or less. The lower limit of the haze value of the coating film after scratching is ideally 0% from the viewpoint of transparency, but it may be more than 0%.

[0031] In the second embodiment, the haze value can be controlled within the above-mentioned numerical range by using modified nanocellulose as a filler, and from the viewpoint of keeping the haze value lower, it is preferable to use nanocellulose derived from oxidized cellulose obtained by oxidation with hypochlorous acid or a salt thereof.

[0032] (Flexibility) The flexibility test can be performed with reference to JIS K 5600-5-1. Using a mandrel tester, for example, a cylindrical mandrel flex tester (manufactured by Allgood), the diameter of the smallest jig that does not crack the coating film after the test is taken as the mandrel diameter in the mandrel test of the cured product. The presence or absence of cracks in the coating film after the test is determined visually by holding the film up to light, and ignoring the coating film surface within 10 mm from the edge of the test plate, if there is one or more white straight lines on the film, it is considered to have cracks, and if there are no lines, it is considered to have no cracks. The flexibility test can be specifically performed by the method described in the examples. In the second embodiment, "in a mandrel test of a cured product, the smallest diameter of the mandrel that does not cause cracks in the cured product is 10 mm or less" refers to a coating film having a thickness in the range of 10 μm to 20 μm, preferably 15 μm±3 μm, in accordance with JIS K 5600-5-1, and the smallest diameter of the mandrel that does not cause cracks in the film after the mandrel test is 10 mm or less.

[0033] In a second embodiment, the minimum diameter of the mandrel in the mandrel test is 10 mm or less, preferably 9 mm or less, more preferably 8 mm or less, even more preferably 7 mm or less, still more preferably 6 mm or less, and even more preferably 5 mm or less. The lower limit of the minimum diameter may be more than 0 mm, and may be 1 mm or more, or 2 mm or more.

[0034] The minimum diameter of the mandrel can be controlled within the above-mentioned range by using modified nanocellulose as a filler. From the viewpoint of improving flexibility, it is preferable to use nanocellulose derived from oxidized cellulose obtained by oxidation with hypochlorous acid or its salt. Furthermore, by using modified nanocellulose as a filler, both flexibility and pencil hardness can be achieved.

[0035] [Modified Nanocellulose] The active energy ray-curable composition according to this embodiment contains modified nanocellulose. The modified nanocellulose is nanocellulose into which a modifying group has been introduced.

[0036] The modified nanocellulose in this embodiment preferably has the structure (i) (i.e., a structure in which a modifying group is introduced into at least some of the hydroxyl groups of the nanocellulose via a covalent bond). In the structure (i), the hydroxyl groups of the nanocellulose into which the modifying group has been introduced are preferably represented by the following formula (1): R-C(=O)-O- (1) [R is a substituted or unsubstituted alkyl group, or a substituted or unsubstituted cycloalkyl group]. The hydroxyl groups into which the modifying group has been introduced are preferably primary hydroxyl groups.

[0037] In formula (1), R is a substituted or unsubstituted alkyl group or a substituted or unsubstituted cycloalkyl group. The alkyl group may be linear or branched.

[0038] The alkyl group for R preferably has 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms, and even more preferably 1 or 2 carbon atoms.

[0039] The cycloalkyl group for R preferably has 3 to 14 carbon atoms, more preferably 4 to 10 carbon atoms, and even more preferably 5 or 6 carbon atoms.

[0040] The alkyl group or cycloalkyl group represented by R 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).

[0041] From the viewpoint of forming a cured product having superior strength, it is preferable that the alkyl group or cycloalkyl group for R is unsubstituted (i.e., consists of only carbon and hydrogen).

[0042] The modifying group may be of one type or of multiple types.

[0043] The modifying group (R-C(=O)-) in formula (1) can be introduced, for example, by reacting nanocellulose with a modifying group-introducing compound (1). The modifying group-introducing compound (1) is preferably a saturated monocarboxylic acid compound and / or a saturated dicarboxylic acid compound. In this specification, saturated monocarboxylic acid compounds and saturated dicarboxylic acid compounds also include their acid anhydrides.

[0044] The modifying group in formula (1) is preferably a group derived from a saturated monocarboxylic acid and / or a saturated dicarboxylic acid. Specifically, the modifying group in formula (1) is preferably the residue of a saturated monocarboxylic acid and / or a saturated dicarboxylic acid that is attached to the nanocellulose as a result of the reaction of the saturated monocarboxylic acid and / or the saturated dicarboxylic acid with the nanocellulose.

[0045] Examples of saturated monocarboxylic acids include formic acid, acetic acid, propionic acid, and butyric acid. Among these, acetic acid is preferred, that is, the modifying group in formula (1) is preferably an acetyl group.

[0046] Saturated dicarboxylic acids include, for example, succinic acid, glutaric acid, adipic acid, suberic acid, and sebacic acid.

[0047] The degree of modification with the modifying group in formula (1) (hereinafter also referred to as "degree of substitution") is preferably 0.05 to 2.5, more preferably 0.1 to 2.2, and even more preferably 0.12 to 2.0, from the viewpoint of further improving the strength and / or elongation of the cured product. The degree of modification (degree of substitution) can be measured by the method described in the examples.

[0048] Furthermore, in the structure (i), the modifying group may have a carbon-carbon unsaturated bond (hereinafter simply referred to as an "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.

[0049] In the structure of (i), the hydroxyl group of nanocellulose into which a modifying group has been introduced is preferably represented by the following formula (2). The hydroxyl group into which a modifying group has been introduced is preferably a primary hydroxyl group. R １ -C(=O)-O- (2)

[0050] R in formula (2) １ is an alkenyl group or a cycloalkenyl group. The alkenyl group may be linear or branched.

[0051] 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.

[0052] R １ The 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.

[0053] 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).

[0054] 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).

[0055] The modifying group (R １ The -C(=O)- group can be introduced, for example, by reacting nanocellulose with a modifying group-introducing compound (2). The modifying group-introducing compound (2) is preferably a monocarboxylic acid compound having an unsaturated bond (hereinafter simply referred to as an "unsaturated monocarboxylic acid compound") and / or a dicarboxylic acid compound having an unsaturated bond (hereinafter simply referred to as an "unsaturated dicarboxylic acid compound"). In this specification, the unsaturated monocarboxylic acid compound and the unsaturated dicarboxylic acid compound also include their acid anhydrides.

[0056] The modifying group in formula (2) is preferably a group derived from an unsaturated monocarboxylic acid and / or an unsaturated dicarboxylic acid. Specifically, the modifying group in formula (2) is preferably the residue of an unsaturated monocarboxylic acid and / or an unsaturated dicarboxylic acid that is attached to the nanocellulose as a result of the reaction of the unsaturated monocarboxylic acid and / or the unsaturated dicarboxylic acid with the nanocellulose.

[0057] Examples of unsaturated monocarboxylic acids include (meth)acrylic acid, 2-ethylacrylic acid, 2-propylacrylic acid, and 2-isopropylacrylic acid.

[0058] Unsaturated dicarboxylic acids include, for example, maleic acid, fumaric acid, itaconic acid, and alkenyl-substituted succinic acid.

[0059] The degree of modification by the modifying group in formula (2) (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. The degree of modification (degree of substitution) can be measured by the method described in the examples.

[0060] The hydroxyl groups of nanocellulose to which a modifying group has been introduced may be a combination of formula (1) and formula (2).

[0061] The modified nanocellulose in this embodiment may have the structure (ii) (i.e., a structure in which the modifying group is introduced to at least some of the carboxy groups of the nanocellulose via an ionic bond). In the structure (ii), the modifying group preferably has an amino group. It is preferable that an ionic bond is formed between the amino group of the modifying group and the carboxy group of the nanocellulose. The amino group of the modifying group may exist in the form of an ammonium ion.

[0062] The modifying group having an amino group may be of one type or of multiple types.

[0063] A modifying group having an amino group can be introduced, for example, by reacting nanocellulose having a carboxy group with a modifying group-introducing compound (3) having an amino group. The modifying group having an amino group can also be expressed as a modifying group-introducing compound (3) that is ionically bonded to the carboxy group of nanocellulose. The modifying group-introducing compound (3) will be described below, but the modifying group having an amino group may have the same structure as the modifying group-introducing compound (3), except for the ionic bond with nanocellulose.

[0064] The modifying group-introducing compound (3) is a compound that reacts with nanocellulose to introduce a modifying group having an amino group into the carboxy group of nanocellulose.

[0065] The number of amino groups in the modifying group-introducing compound (3) is, for example, 1 to 4, 1 to 3, 1 or 2, or 1 per molecule.

[0066] The modifying group-introducing compound (3) preferably has a long-chain linear or long-chain branched structure. The amino group is preferably located at a terminal of the molecule. The amino group may be located at only one terminal of the molecule, at multiple terminals of the molecule, or at all terminals of the molecule.

[0067] The modifying group-introducing compound (3) preferably has an oxyalkylene group, more preferably a plurality of oxyalkylene groups (polyoxyalkylene groups). In this specification, a compound having an amino group and a polyoxyalkylene group is referred to as a polyetheramine.

[0068] The oxyalkylene group is preferably an oxyalkylene group having 1 to 6 carbon atoms, more preferably an oxyalkylene group having 2 to 4 carbon atoms, and even more preferably an oxyalkylene group having 2 or 3 carbon atoms.

[0069] The oxyalkylene group preferably contains at least one selected from the group consisting of an oxyethylene group, an oxypropylene group, and an oxybutylene group, and more preferably contains an oxyethylene group and / or an oxypropylene group.

[0070] The number of repeating units of the oxyalkylene group is preferably 5 to 70, more preferably 10 to 50, and even more preferably 20 to 45.

[0071] From the viewpoint of further improving the strength and / or elongation of the cured product, the weight average molecular weight of the modifying group-introducing compound (3) is preferably 200 to 5000, more preferably 300 to 4000, and even more preferably 400 to 2500. The weight average molecular weight can be measured by gel permeation chromatography (GPC).

[0072] The amount of the modifying group-introducing compound (3) used is preferably 0.5 to 2.0 equivalents, more preferably 0.7 to 1.5 equivalents, and even more preferably 0.9 to 1.1 equivalents relative to the amount (mol) of carboxy groups in nanocellulose.

[0073] The amount of modified nanocellulose contained in the active energy ray-curable composition of this embodiment is preferably 0.1 to 20.0 mass%, more preferably 0.3 to 15.0 mass%, even more preferably 0.5 to 10.0 mass%, and still more preferably 0.5 to 7.0 mass%, based on the mass of the active energy ray-curable monomer.

[0074] 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 first oxidizing the cellulosic raw material.

[0075] 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).

[0076] From the viewpoint of forming a cured product that has better scratch resistance and transparency and can further balance flexibility and pencil hardness, it is preferable to use hypochlorous acid or a salt thereof as the oxidizing agent. In other words, nanocellulose is preferably produced by oxidizing a cellulose-based raw material with hypochlorous acid or a salt thereof (without using an N-oxyl compound) and nano-sizing the resulting oxidized cellulose.

[0077] 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, it has better dispersibility than when nanocellulose obtained by other methods (for example, TEMPO oxidation) is mixed, and as a result, it is possible to form a cured product that has excellent scratch resistance and transparency, and is able to achieve both flexibility and pencil hardness.

[0078] 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.

[0079] [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.

[0080] Examples of hypochlorous acid or salts thereof include hypochlorous acid water, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, and ammonium hypochlorite.

[0081] 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%.

[0082] The definition of the effective chlorine concentration of hypochlorous acid or a salt thereof is as described in WO 2022 / 009979.

[0083] 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.

[0084] (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).

[0085] 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."

[0086] 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.).

[0087] (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.

[0088] The amount of carboxy groups in oxidized cellulose can be measured by the method described in WO 2022 / 009979.

[0089] 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.

[0090] 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.

[0091] 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. １３In 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.

[0092] 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.

[0093] 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.

[0094] (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.

[0095] 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.

[0096] [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.

[0097] [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.

[0098] 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).

[0099] 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.

[0100] Nanocellulose is a collection of individual fibers. Nanocellulose may include cellulose fibers having carboxy groups, nanocellulose without carboxy groups, or a mixture of these. Furthermore, when nanocellulose includes cellulose fibers having carboxy groups (hereinafter also referred to as carboxylated nanocellulose) as one aspect of nanocellulose, it is sufficient to include 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.

[0101] (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.

[0102] (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.

[0103] (Average fiber length) The average fiber length of nanocellulose is preferably 10 to 3000 nm, more preferably 10 to 2000 nm, even more preferably 10 to 800 nm, still more preferably 50 to 500 nm, and particularly preferably 60 to 300 nm.

[0104] (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.

[0105] The average fiber length and average fiber width of nanocellulose can be measured by the method described in WO 2022 / 009980.

[0106] (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.

[0107] 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.

[0108] (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.

[0109] The zeta potential can be measured by the method described in WO 2022 / 009980.

[0110] (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%.

[0111] Crystallinity was measured using solid nanocellulose for freeze-dried nanocellulose. １３C-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.]

[0112] [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.).

[0113] [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.

[0114] In the first embodiment, the active energy ray-curable monomer includes a polyfunctional monomer. A polyfunctional monomer is a monomer having two or more functional groups (preferably polymerizable functional groups) in one molecule. Examples of the polymerizable functional group include the ethylenically unsaturated groups described below. The polyfunctional monomer is preferably a compound having two or more ethylenically unsaturated groups (preferably (meth)acryloyl groups) in one molecule. The number of polymerizable functional groups is not particularly limited, but is preferably 2 to 25, more preferably 2 to 20, even more preferably 2 to 15, and even more preferably 2 to 8.

[0115] In the third embodiment, the active energy ray-curable monomer is a monomer that, when the active energy ray-curable monomer is cured in air or a nitrogen atmosphere, results in a cured product with a storage modulus of 0.5 × 10^8 Pa or more at 25°C. When the storage modulus is 0.5 × 10^8 Pa or more at 25°C, the cured product has excellent hardness, and when combined with modified nanocellulose, a cured product can be formed that has both flexibility and pencil hardness.

[0116] The storage modulus in the third embodiment is preferably 0.8×10^8 Pa or more, more preferably 1.0×10^8 Pa or more, even more preferably 2.0×10^8 Pa or more, and still more preferably 4.0×10^8 Pa or more. There is no particular upper limit to the storage modulus, but it is usually 20×10^9 Pa or less, and may be 17×10^9 Pa or less, or may be 15×10^9 Pa or less. The storage modulus is measured by dynamic viscoelasticity measurement at a frequency of 1 Hz.

[0117] Specifically, the storage modulus can be measured by the method described in the Examples.

[0118] The storage modulus can be controlled within the above range by appropriately selecting an active energy ray-curable monomer described later or by appropriately combining active energy ray-curable monomers. In addition, for example, the storage modulus can be controlled by using a monomer having two or more functional groups as the active energy ray-curable monomer, and the storage modulus can also be controlled by controlling the amount of the monomer used.

[0119] In the fourth embodiment, the active energy ray-curable monomer is a monomer that, when the active energy ray-curable monomer is cured in air or a nitrogen atmosphere, results in a cured product with an indentation modulus of 0.5 × 10^8 Pa or more at 30°C. When the indentation modulus at 30°C is 0.5 × 10^8 Pa or more, the hardness of the cured product is excellent, and when combined with modified nanocellulose, a cured product can be formed that has both flexibility and pencil hardness.

[0120] The indentation modulus in the fourth embodiment is preferably 0.8×10^8 Pa or more, more preferably 1.0×10^8 Pa or more, even more preferably 2.0×10^8 Pa or more, and still more preferably 4.0×10^8 Pa or more. There is no particular upper limit to the indentation modulus, but it is usually 20×10^9 Pa or less, and may be 17×10^9 Pa or less, or 15×10^9 Pa or less.

[0121] The indentation elastic modulus can be measured by the method described in the examples.

[0122] The indentation modulus can be controlled within the above range by appropriately selecting an active energy ray-curable monomer described later or by appropriately combining active energy ray-curable monomers. For example, the indentation modulus can be controlled by using a monomer having two or more functional groups as the active energy ray-curable monomer, and the indentation modulus can also be controlled by controlling the amount of the monomer used.

[0123] 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.

[0124] 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.

[0125] (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.

[0126] 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).

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] (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.

[0132] 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.

[0133] (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.

[0134] Examples of the (meth)acrylamide-based compound include the following compounds:

[0135] N-alkylacrylamides such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and Nt-butyl(meth)acrylamide.

[0136] N,N-dialkylacrylamides such as N,N-dimethyl(meth)acrylamide and N,N-diethyl(meth)acrylamide.

[0137] N-hydroxyalkyl(meth)acrylamides such as N-hydroxyethyl(meth)acrylamide and N-methylol(meth)acrylamide.

[0138] N-alkoxyalkyl(meth)acrylamides such as N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, and N-methoxyethyl(meth)acrylamide.

[0139] (Meth)acryloylmorpholine.

[0140] (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.

[0141] An example of a (meth)acrylate having an oxazolidone group is 2-(2-oxo-3-oxazolidinyl)ethyl (meth)acrylate.

[0142] (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.

[0143] Examples of compounds having a maleimide group include (meth)acrylates having a hexahydrophthalimide group and (meth)acrylates having a tetrahydrophthalimide group.

[0144] An example of a (meth)acrylate having a hexahydrophthalimide group is N-(meth)acryloyloxyethylhexahydrophthalimide.

[0145] An example of a (meth)acrylate having a tetrahydrophthalimide group is N-(meth)acryloyloxyethyltetrahydrophthalimide.

[0146] (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").

[0147] 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.

[0148] {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.

[0149] Low molecular weight diols include, for example, ethylene glycol, propylene glycol, cyclohexanedimethanol, neopentyl glycol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol.

[0150] 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.

[0151] Examples of diols having a polyether skeleton include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

[0152] 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).

[0153] {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.

[0154] Aliphatic polyisocyanates include, for example, hexamethylene diisocyanate, tetramethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate.

[0155] 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.

[0156] An example of the polyisocyanate having a heterocycle is hexamethylene diisocyanate trimer.

[0157] Examples of aromatic polyisocyanates include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, paraphenylene diisocyanate, and 1,5-naphthalene diisocyanate.

[0158] {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)."

[0159] 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.

[0160] 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.

[0161] (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.

[0162] {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.

[0163] {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.

[0164] (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.

[0165] {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.

[0166] {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.

[0167] (Other Compounds) Examples of other compounds having an ethylenically unsaturated group include the following compounds.

[0168] 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.

[0169] (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.

[0170] Alkoxyalkyl (meth)acrylates such as 2-methoxyethyl (meth)acrylate and 2-ethoxyethoxyethyl (meth)acrylate.

[0171] (Meth)acrylates having a heterocyclic ring, such as tetrahydrofurfuryl (meth)acrylate, glycerin carbonate (meth)acrylate, and isosorbide diacrylate.

[0172] (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.

[0173] (Meth)acrylates such as glycidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and allyl (meth)acrylate.

[0174] 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.

[0175] 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.

[0176] Hydroxypivalic acid neopentyl glycol di(meth)acrylate, and hydroxypivalic acid neopentyl glycol ε-caprolactone-modified di(meth)acrylate.

[0177] Bifunctional (meth)acrylates having an alicyclic skeleton, such as dimethyloltricyclodecane di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, and spiroglycol di(meth)acrylate.

[0178] 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, glycerin triacrylate, glycerin alkylene oxide-modified triacrylate.

[0179] The active energy ray-curable monomer may be one type or a plurality of types.

[0180] 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.

[0181] 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.

[0182] [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.

[0183] Examples of the photopolymerization initiator include the following compounds:

[0184] 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.);

[0185] 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.

[0186] 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.

[0187] 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.

[0188] Acridone and acridone-based compounds such as 10-butyl-2-chloroacridone.

[0189] 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).

[0190] 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.

[0191] Acridine derivatives such as 9-phenylacridine and 1,7-bis(9,9'-acridinyl)heptane.

[0192] Adeka Optomer N-1414 (manufactured by ADEKA Corporation), phenylglyoxylic acid methyl ester, ethyl anthraquinone, and phenanthrenequinone.

[0193] 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.

[0194] [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.

[0195] <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.

[0196] Examples of active energy rays include ultraviolet rays, visible light, and electron beams.

[0197] 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.

[0198] 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.

[0199] Irradiation with active energy rays may be carried out, for example, in air or in a nitrogen atmosphere, preferably in a nitrogen atmosphere. Irradiation in a nitrogen atmosphere can further improve the flexibility and pencil hardness of the cured product.

[0200] <Cured Product> One embodiment of the present invention relates to a cured product obtained by curing the above-described active energy ray-curable composition.

[0201] The shape of the cured product is not particularly limited, but is preferably a cured film.

[0202] The thickness of the cured film is not particularly limited, but may be, for example, 1 to 200 μm, 1 to 100 μm, 1 to 80 μm, or 1 to 50 μm.

[0203] The preferred values ​​of the pencil hardness, scratch resistance, and flexibility of the cured film are as described above in the sections (Pencil hardness), (Scratch resistance), and (Flexibility).

[0204] 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, resists for color filters, resists for black matrices, 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, anti-rust coating materials, waterproof coating materials, hot water-resistant coating materials, nanoimprint materials, compositions for image recording materials using microcapsules, and various devices.

[0205] 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.

[0206] 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.

[0207] <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).

[0208] [Degree of modification (degree of substitution) of modified nanocellulose] The degree of modification (degree of substitution) of the acetic acid-modified (acetylated) nanocellulose obtained in Production Example 1 below was measured as follows.

[0209] 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.

[0210] 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

[0211] 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 ７A(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

[0212] The Q (mol) previously determined by titration satisfies the following formula 2: Q (mol) = 2y + z... formula 2

[0213] 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

[0214] 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

[0215] 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.

[0216] <Production of modified nanocellulose> [Production Example 1: Acetyl-modified 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.

[0217] 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.

[0218] 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.

[0219] 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.

[0220] (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.

[0221] (Acetylation modification) To 1 part by mass of the acetone-substituted H-type nanocellulose obtained in the above defibration process, 1.5 parts by mass of acetic anhydride, 0.05 parts by mass of 70% perchloric acid, 6.0 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, the mixture was washed (substituted) with methanol seven times using a tabletop multi-rack centrifuge (KOKUSAN, H-40α) to obtain acetylated modified H-type nanocellulose.

[0222] The degree of substitution of the modified nanocellulose was measured, and the degree of substitution with acetic acid was 1.68.

[0223] <Production of Active Energy Ray-Curable Composition and Cured Product> [Example 1] A composite prepared by mixing Aronix M-305 (pentaerythritol tri- and tetraacrylate) (manufactured by Toagosei Co., Ltd.) and acryloylmorpholine (ACMO (registered trademark), manufactured by KJ Chemical Co., Ltd.) in a weight ratio of 6:4 was mixed with a 1 wt % acetone dispersion of acetyl-modified nanocellulose prepared in Production Example 1, and the mixture was stirred for 10 minutes or more. This mixture was evaporated to remove the solvent, and the solvent was adjusted to 50-60%, obtaining a mixed liquid as an active energy ray-curable composition. 2 parts by mass of photoradical initiator Omnirad 184 (IBM Resins B.V.) was added to 100 parts of the obtained composite liquid (i.e., the active energy ray-curable composition) and dissolved. The obtained composite liquid was applied to a corona-treated 100 μm-thick PET film using a bar coater, and after the solvent in the coating liquid was sufficiently evaporated, the film was irradiated with UVA light at an integrated illuminance of 1500 mW / cm using a conveyor-type ultraviolet irradiation device (manufactured by Eye Graphics Co., Ltd., US5-X0602). ２ The composite was cured by irradiating with UV light to obtain a 2 wt% acetyl-modified nanocellulose composite M-305 / ACMO coating. The storage modulus of the cured product obtained by curing a composite consisting only of M-305 and ACMO (weight ratio 6:4) in air was 4.5 x 10^9 Pa at 25 ° C., and the indentation modulus at 30 ° C. was 4.9 x 10^9 Pa. The storage modulus was measured at a frequency of 1 Hz by dynamic viscoelasticity measurement using a TA Instruments DMA850. The indentation modulus was measured using an ENT-NEXUS (manufactured by Elionix) Berkovich indenter with an indentation depth of 1000 nm, load-unload division number of 500, step interval of 30 msec, and a maximum load holding time of 5000 msec. A load-unload test was performed five times for each sample, and the median value of the obtained modulus was used.

[0224] [Example 2] A nanocellulose composite M-305 / ACMO was obtained in the same manner as in Example 1, except that the concentration of acetyl-modified nanocellulose was 5 wt%.

[0225] [Example 3] A nanocellulose composite M-305 / ACMO was obtained in the same manner as in Example 1, except that the concentration of acetyl-modified nanocellulose was 10 wt%.

[0226] [Comparative Example 1] An M-305 / ACMO coating film was obtained in the same manner as in Example 1, except that acetyl-modified nanocellulose was not added.

[0227] Comparative Example 2 An M-305 / ACMO coating film was obtained in the same manner as in Example 1, except that commercially available silica particles Φ100 nm were added to a concentration of 2 wt % instead of acetyl-modified nanocellulose.

[0228] Comparative Example 3 An M-305 / ACMO coating film was obtained in the same manner as in Example 1, except that commercially available silica particles Φ100 nm were added in place of the acetyl-modified nanocellulose to a concentration of 5 wt %.

[0229] Comparative Example 4 An M-305 / ACMO coating film was obtained in the same manner as in Example 1, except that commercially available silica particles Φ500 nm were added to a concentration of 5 wt % instead of acetyl-modified nanocellulose.

[0230] Comparative Example 5 An M-305 / ACMO coating film was obtained in the same manner as in Example 1, except that commercially available silica particles Φ500 nm were added in place of the acetyl-modified nanocellulose so as to have a concentration of 10 wt %.

[0231] Comparative Example 6 An M-305 / ACMO coating film was obtained in the same manner as in Example 1, except that commercially available silica particles Φ500 nm were added in place of the acetyl-modified nanocellulose so as to have a concentration of 20 wt %.

[0232] Comparative Example 7 A coating film was obtained in the same manner as in Comparative Example 1, except that the monomer was changed to M-113 (nonylphenol EO-modified acrylate) (manufactured by Toagosei Co., Ltd.). The storage modulus at 25°C of the cured product obtained by curing a composite consisting only of M-113 was 9.6 x 10^4 Pa. The storage modulus was measured at a frequency of 1 Hz using a dynamic viscoelasticity analyzer (manufactured by TA Instruments, DMA850).

[0233] Comparative Example 8 A coating film was obtained in the same manner as in Example 1, except that the monomer was changed to M-113 (manufactured by Toagosei).

[0234] <Evaluation of Cured Products> Physical properties were evaluated by the following pencil hardness test, scratch resistance test, haze measurement, and flexibility test. The thickness of the coating film used for the physical property evaluation was 15 μm±3 μm in all cases.

[0235] (Pencil Hardness Test) The pencil hardness test was carried out in accordance with JIS KS5600-5-4. Specifically, the pencil hardness test was carried out using a VF2380-13O (manufactured by Cortec) at N3, and the maximum pencil hardness at which no indentation was observed was recorded as the pencil hardness.

[0236] (Abrasion Resistance Test and Haze Measurement) In the abrasion resistance test, steel wool (manufactured by Bonstar Sales, #0000) was pressed against a cut-out film at a surface pressure of 0.6 KPa and rubbed back and forth in one direction 200 times. The degree of scratching of the sample before and after abrasion was evaluated by the haze measurement described below. Haze measurement was performed in accordance with JIS K7136. Specifically, evaluation was performed using a COH7700 (manufactured by Nippon Denshoku Industries Co., Ltd.). Images of the coating films of Examples 1-2 and Comparative Examples 1-2 that were subjected to the abrasion resistance test are shown in Figure 1. For each of the coating films of Examples 1-2 and Comparative Examples 1-2 in Figure 1, the left half of the coating film is before abrasion and the right half is after abrasion.

[0237] (Flexibility Test) The flexibility test was performed with reference to JIS K 5600-5-1. A mandrel tester (a cylindrical mandrel flexure tester manufactured by Allgood) was used, and the diameter of the smallest jig that did not cause cracks in the coating film after the test was recorded. The presence or absence of cracks in the coating film after the test was determined visually by holding the film up to light. Ignoring the coating film surface within 10 mm from the edge of the test plate, a film with one or more straight white streaks was judged to have cracks, and a film with no streaks was judged to have no cracks.

[0238]

[0239] [Example 4] The atmosphere during UV irradiation was N ２ A nanocellulose composite M-305 / ACMO was prepared in the same manner as in Example 1, except that it was replaced with. The indentation modulus at 30 ° C of the cured product obtained by curing a composite consisting only of M-305 and ACMO (weight ratio 6:4) under a nitrogen atmosphere was 4.6 × 10^9 Pa. The indentation modulus was measured using an ENT-NEXUS (manufactured by Elionix) Berkovich indenter, with an indentation depth of 1000 nm, load-unload division number of 500, step interval of 30 msec, and a maximum load holding time of 5000 msec. A load-unload test was performed n = 5 times for one sample, and the median value of the obtained modulus was used.

[0240] [Example 5] Nanocellulose composite M-305 / ACMO was obtained in the same manner as in Example 4, except that the concentration of acetyl-modified nanocellulose was 5 wt%.

[0241] [Example 6] Nanocellulose composite M-305 / ACMO was obtained in the same manner as in Example 4, except that the concentration of acetyl-modified nanocellulose was 10 wt%.

[0242] [Comparative Example 9] An M-305 / ACMO coating film was obtained in the same manner as in Example 4, except that acetyl-modified nanocellulose was not added.

[0243] [Comparative Example 10] An M-305 / ACMO coating film was obtained in the same manner as in Example 4, except that commercially available silica particles Φ15 nm were added in place of the acetyl-modified nanocellulose so as to have a concentration of 2 wt%.

[0244] [Comparative Example 11] An M-305 / ACMO coating film was obtained in the same manner as in Example 4, except that commercially available silica particles Φ15 nm were added in place of the acetyl-modified nanocellulose so as to have a concentration of 5 wt%.

[0245] [Comparative Example 12] An M-305 / ACMO coating film was obtained in the same manner as in Example 4, except that commercially available silica particles Φ15 nm were added instead of acetyl-modified nanocellulose so that the concentration was 10 wt%.

[0246] The above-mentioned pencil hardness test and flex test were carried out on each coating film, and the results are shown in Table 2.

[0247]

[0248] [Example 7] Nanocellulose composite M-450 / ACMO was prepared in the same manner as in Example 4, except that the monomer composition was changed to a composite of Aronix M-450 (pentaerythritol tri- and tetraacrylate) (manufactured by Toagosei Co., Ltd.) and acryloylmorpholine (ACMO (registered trademark), manufactured by KJ Chemical Co., Ltd.) mixed in a weight ratio of 6:4. The indentation modulus at 25 ° C. of the cured product obtained by curing a composite consisting only of M-450 and ACMO (weight ratio 6:4) under a nitrogen atmosphere was 4.6 × 10^9 Pa. Here, the indentation modulus was measured using an ENT-NEXUS (manufactured by Elionix) Berkovich indenter, with an indentation depth of 1000 nm, load-unloading division number of 500, step interval of 30 msec, and a maximum load holding time of 5000 msec. A load-unloading test was performed n = 5 times for one sample, and the median value of the obtained modulus was used.

[0249] [Example 8] Nanocellulose composite M-450 / ACMO was obtained in the same manner as in Example 7, except that the concentration of acetyl-modified nanocellulose was 5 wt%.

[0250] [Comparative Example 13] An M-450 / ACMO coating film was obtained in the same manner as in Example 7, except that acetyl-modified nanocellulose was not added.

[0251] [Comparative Example 14] An M-450 / ACMO coating film was obtained in the same manner as in Example 7, except that commercially available silica particles Φ15 nm were added instead of acetyl-modified nanocellulose so as to have a concentration of 5 wt%.

[0252] The above-mentioned pencil hardness test and flex test were carried out on each coating film, and the results are shown in Table 3.

[0253]

[0254] Example 9 A nanocellulose composite M-930 / ACMO was prepared in the same manner as in Example 4, except that the monomer composition was changed to a composite of Aronix M-930 (glycerin triacrylate) (manufactured by Toagosei Co., Ltd.) and acryloylmorpholine (ACMO (registered trademark), manufactured by KJ Chemical Co., Ltd.) mixed in a weight ratio of 8:2. The indentation modulus at 25 ° C. of the cured product obtained by curing a composite consisting only of M-930 and ACMO (weight ratio 8:2) under a nitrogen atmosphere was 4.6 × 10^9 Pa. Here, the indentation modulus was measured using an ENT-NEXUS (manufactured by Elionix) Berkovich indenter, with an indentation depth of 1000 nm, load-unload division number of 500, step interval of 30 msec, and a maximum load holding time of 5000 msec. A load-unload test was performed n = 5 times for one sample, and the median value of the obtained modulus was used.

[0255] [Comparative Example 15] An M-930 / ACMO coating film was obtained in the same manner as in Example 9, except that acetyl-modified nanocellulose was not added.

[0256] [Comparative Example 16] An M-930 / ACMO coating film was obtained in the same manner as in Example 9, except that commercially available silica particles Φ15 nm were added instead of acetyl-modified nanocellulose so as to have a concentration of 2 wt%.

[0257] [Comparative Example 17] An M-930 / ACMO coating film was obtained in the same manner as in Example 9, except that commercially available silica particles Φ15 nm were added instead of acetyl-modified nanocellulose to a concentration of 5 wt%.

[0258] [Comparative Example 18] An M-930 / ACMO coating film was obtained in the same manner as in Example 9, except that commercially available silica particles Φ15 nm were added instead of acetyl-modified nanocellulose so that the concentration was 10 wt%.

[0259] The above-mentioned pencil hardness test and flex test were carried out on each coating film, and the results are shown in Table 4.

[0260]

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, and the modified nanocellulose has the following structure (i) and / or (ii): (i) a structure in which the modifying group is introduced to at least some of the hydroxyl groups of the nanocellulose via a covalent bond; (ii) a structure in which the modifying group is introduced to at least some of the carboxyl groups of the nanocellulose via an ionic bond; and the active energy ray-curable monomer comprises a polyfunctional monomer.

2. An active energy ray-curable composition comprising: a 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 modified nanocellulose has the following structure (i) and / or (ii): (i) a structure in which the modifying group is introduced to at least some of the hydroxyl groups of the nanocellulose via a covalent bond; (ii) a structure in which the modifying group is introduced to at least some of the carboxyl groups of the nanocellulose via an ionic bond; and an active energy ray-curable composition, wherein, when the active energy ray-curable composition is cured in air or under a nitrogen atmosphere, in a mandrel test of the cured product, the smallest diameter of the mandrel that does not crack the cured product is 10 mm or less, and the pencil hardness of the cured product is the same as or is improved by at least one level compared to a cured product that does not contain nanocellulose.

3. An active energy ray-curable composition comprising: a modified nanocellulose; and an active energy ray-curable monomer, wherein the modified nanocellulose comprises: nanocellulose; and a modifying group introduced into the nanocellulose, and the modified nanocellulose has the following structure (i) and / or (ii): (i) a structure in which the modifying group is introduced to at least some of the hydroxyl groups of the nanocellulose via a covalent bond; (ii) a structure in which the modifying group is introduced to at least some of the carboxyl groups of the nanocellulose via an ionic bond; and the active energy ray-curable monomer is a monomer that, when the active energy ray-curable monomer is cured in air or under a nitrogen atmosphere, results in a storage modulus of the cured product at 25°C of 0.5 x 10^8 Pa or more.

4. An active energy ray-curable composition comprising: a modified nanocellulose; and an active energy ray-curable monomer, wherein the modified nanocellulose comprises: nanocellulose; and a modifying group introduced into the nanocellulose, and the modified nanocellulose has the following structure (i) and / or (ii): (i) a structure in which the modifying group is introduced to at least some of the hydroxyl groups of the nanocellulose via a covalent bond; (ii) a structure in which the modifying group is introduced to at least some of the carboxyl groups of the nanocellulose via an ionic bond; and the active energy ray-curable monomer is a monomer that, when the active energy ray-curable monomer is cured in air or under a nitrogen atmosphere, results in a cured product with an indentation modulus of elasticity of 0.5 x 10^8 Pa or more at 30°C.

5. The active energy ray-curable composition according to claim 3, wherein the cured product has a storage modulus at 25°C of 2.0 x 10^8 Pa or more.

6. The active energy ray-curable composition according to any one of claims 1 to 4, wherein the modified nanocellulose has the structure (i), and the hydroxyl group to which the modifying group has been introduced is represented by the following formula (1): R-C(=O)-O- (1) [R is a substituted or unsubstituted alkyl group, or a substituted or unsubstituted cycloalkyl group].

7. The active energy ray-curable composition according to any one of claims 1 to 4, wherein the modified nanocellulose has the structure (i), and the modifying group is an acetyl group.

8. The active energy ray-curable composition according to any one of claims 1 to 4, 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.

9. The active energy ray-curable composition according to any one of claims 1 to 4, 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 dicarboxy groups.

10. The active energy ray-curable composition according to any one of claims 1 to 4, wherein the average fiber width of the modified nanocellulose is 1 to 10 nm.

11. The active energy ray-curable composition according to any one of claims 1 to 4, wherein the average fiber length of the modified nanocellulose is 10 to 800 nm.

12. The active energy ray-curable composition according to any one of claims 1 to 4, further comprising a photopolymerization initiator.

13. A cured product of the active energy ray-curable composition according to any one of claims 1 to 4.

14. The cured product according to claim 13, wherein the cured product is a cured film.

15. The cured product according to claim 14, wherein in a mandrel test of the cured film, the minimum diameter of the mandrel that does not cause cracks in the cured film is 10 mm or less, and the pencil hardness of the cured film is 2H or more.

16. 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 4 with active energy rays to cure the composition.

17. The method of claim 16, wherein the irradiation is carried out in a nitrogen atmosphere.

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