Active energy ray curable composition and cured product thereof

Abstract

To provide an active energy ray-curable composition that can give a cured product having improved strength, while retaining its curability.SOLUTION: An active energy ray-curable composition contains nanocellulose and active energy ray-curable monomers.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an active energy ray-curable composition and a cured product thereof. [Background technology]

[0002] Active energy ray-curable compositions that are cured by irradiation with active energy rays such as ultraviolet rays have a short curing time, excellent 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, active energy ray-curable compositions generally have the drawback of producing cured products that are brittle and lack toughness.

[0003] For example, Patent Document 1 proposes a method for improving the mechanical properties, particularly tensile strength, of generally brittle active-energy ray polymers, in which an active-energy ray-curable composition shaped product, in which an active-energy ray-polymerizable compound and a chain polymer are uniformly mixed, is irradiated with active energy rays to form the shaped product into a semi-cured product in a transparent solid state with no fluidity, and then a second irradiation step is performed in which the semi-cured product is further irradiated with active energy rays at a temperature higher than the temperature at which it was irradiated in the first irradiation step and at a temperature equal to or higher than the glass transition temperature of the semi-cured product.

[0004] Patent Document 2 discloses a curable composition for producing a resin sheet, comprising the following components (A) to (C), where the total amount of components (A) to (C) is 100% by weight, and the components are 2 to 40% by weight of component (A), 10 to 90% by weight of component (B), and 0 to 80% by weight of component (C): component (A): a hydrogen-bonding compound having one ethylenically unsaturated group, component (B): a hydrogen-bonding compound having two or more ethylenically unsaturated groups, and component (C): a compound having an ethylenically unsaturated group, other than components (A) and (B). It is claimed that resin sheets with excellent rigidity and toughness can be obtained from this active energy ray-curable composition.

[0005] In addition to improving strength by the curing method or the composition of the resin itself as described above, a method of improving strength by using a filler such as a filler is known. For example, Patent Document 3 proposes an active energy ray-curable resin composition that contains an energy ray-curable monomer or oligomer, a photopolymerization initiator, and an inorganic filler with a Mohs hardness of 8 or more in order to form a coating that is strong and durable for a long period of time. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-200623 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-117797 [Patent Document 3] Japanese Patent Application Laid-Open No. 2005-213296 Summary of the Invention [Problem to be solved by the invention]

[0007] The method of Patent Document 1 requires two irradiations of active energy rays in the curing process, which poses a problem in terms of improving productivity. In Patent Document 2, the composition of the active energy ray-curable composition must be within a specific range in order to improve strength, and a highly versatile method for improving the strength of the active energy ray-curable composition is required.

[0008] The method of using a filler, as in the active energy ray-curable resin composition of Patent Document 3, is a method of improving resin strength that is excellent in productivity and versatility. However, the active energy ray-curable resin composition of Patent Document 3 uses an inorganic filler with a Mohs hardness of 8 or more, and materials such as alumina as this inorganic filler have a high absorption of active energy rays, which causes a problem of reduced curability.

[0009] Therefore, an object of the present invention is to provide an active energy ray-curable composition that maintains curability and produces a cured product with excellent strength. [Means for solving the problem]

[0010] As a result of extensive research, the present inventors have discovered that an active energy ray-curable composition using nanocellulose can provide a cured product with excellent strength without using a component that absorbs active energy rays (i.e., while maintaining curability), and have thus completed the present invention.

[0011] That is, the present invention is as follows. [1] Contains nanocellulose and active energy ray curable monomers, Active energy ray-curable composition. [2] The nanocellulose comprises an oxidation product of a cellulosic raw material with hypochlorous acid or a salt thereof, and is substantially free of N-oxyl compounds; [1] The active energy ray-curable composition according to [1]. [3] The carboxyl group content of the nanocellulose is 0.2 mmol / g or more and 2.0 mmol / g or less, The active energy ray-curable composition according to [1] or [2]. [4] The average fiber length of the nanocellulose is 50 nm or more and 800 nm or less. The active energy ray-curable composition according to any one of [1] to [3]. [5] The average fiber width of the nanocellulose is 2.0 nm or more and 10.0 nm or less, The active energy ray-curable composition according to any one of [1] to [4]. [6] the active energy ray-curable monomer includes a compound having an ethylenically unsaturated group; The active energy ray-curable composition according to any one of [1] to [5]. [7] The active energy ray-curable monomer includes a hydroxyl group-containing (meth)acrylate. The active energy ray-curable composition according to any one of [1] to [6]. [8] A cured product of the active energy ray-curable composition according to any one of [1] to [7]. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an active energy ray-curable composition that gives a cured product having excellent strength while maintaining curability. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the preferred embodiments. However, the present invention is not limited to the following embodiments and can be practiced in various modified forms within the scope of the present invention. In this specification, an acryloyl group and / or a methacryloyl group is referred to as a (meth)acryloyl group, an acrylate and / or a methacrylate is referred to as a (meth)acrylate, and an acrylic acid and / or a methacrylic acid is referred to as a (meth)acrylic acid.

[0014] The active energy ray-curable composition of the present invention contains nanocellulose and an active energy ray-curable monomer. The active energy ray-curable composition of the present invention is a composition that is cured by irradiation with active energy rays, for example, at least one selected from ultraviolet rays, visible light, electron beams, etc. Among the active energy rays, ultraviolet rays are preferred as the rays to be irradiated onto the active energy ray-curable composition of the present invention.

[0015] <Nanocellulose> The nanocellulose used in the present invention is a nano-sized cellulose-based raw material. The main component of plants is cellulose, and bundles of cellulose molecules are called cellulose microfibrils. The cellulose in cellulosic raw materials is also contained in the form of cellulose microfibrils. In the present invention, nanocellulose is a general term for nanosized cellulose, and includes fine cellulose fibers, cellulose nanocrystals, etc. Fine cellulose fibers are also called cellulose nanofibers (also referred to as CNF).

[0016] The nanocellulose in the present invention may be commercially available nanocellulose, or may be prepared from a cellulosic raw material such as softwood pulp.

[0017] The nanocellulose of the present invention is preferably a nano-sized version of oxidized cellulose obtained by oxidizing a cellulosic raw material. That is, the nanocellulose of the present invention preferably contains oxidized nanocellulose. A preferred oxidation method is oxidation using hypochlorous acid or a salt thereof. Note that oxidation using hypochlorous acid or a salt thereof herein refers to oxidation that occurs when hypochlorous acid or a salt thereof acts on a cellulosic raw material.

[0018] One preferred embodiment of nanocellulose in the present invention is nano-sized oxidized cellulose obtained by oxidizing a cellulosic raw material with hypochlorous acid or a salt thereof. Here, the oxidized cellulose can also be referred to as an oxide of the cellulosic raw material. The nanocellulose in the present invention preferably contains an oxide of the cellulosic raw material with hypochlorous acid or a salt thereof.

[0019] The nanocellulose of the present invention is obtained by oxidizing cellulosic raw materials with hypochlorous acid or its salts, and this oxidation does not involve the use of N-oxyl compounds such as TEMPO. Therefore, the nanocellulose of the present invention is substantially free of N-oxyl compounds. Therefore, nanocellulose has a high level of safety, as the impact of N-oxyl compounds on the environment and human body is sufficiently reduced. Herein, "substantially free of N-oxyl compounds" in nanocellulose means that N-oxyl compounds are not used in the production of oxidized cellulose, or that the content of nitrogen derived from N-oxyl compounds in the oxidized cellulose is 2.0 ppm or less, preferably 1.0 ppm or less. Furthermore, "substantially free of N-oxyl compounds" also refers to cases where the increase in the content of N-oxyl compounds from the cellulosic raw materials is preferably 2.0 ppm by mass or less, more preferably 1.0 ppm by mass or less. The content of N-oxyl compounds can be measured by known means. Examples of known means include a method using a trace total nitrogen analyzer. Specifically, the content of N-oxyl compounds can be measured as the amount of nitrogen using a trace total nitrogen analyzer (manufactured by Mitsubishi Chemical Analytech Co., Ltd., device name: TN-2100H).

[0020] The nanocellulose of the present invention contains a carboxyl group, and the carboxyl group may be in the H type (-COOH) or in the salt type (-COO - X + :X + is an anion forming a salt form), or may be modified by reacting the carboxy group with another compound to form a covalent bond. The type of salt is not particularly limited, and examples include metal salts such as lithium and sodium salts; ammonium salts; and organic amine salts. Suitable examples of the other compound include primary, secondary, and tertiary amines.

[0021] The composition of the present invention can be efficiently obtained by using nanocellulose that contains an oxide of a cellulose-based raw material with hypochlorous acid or its salt and is substantially free of N-oxyl compounds. The nanocellulose can be obtained efficiently because it is obtained from oxidized cellulose, which has excellent defibrillation properties. Therefore, the composition of the present invention can also be efficiently obtained.

[0022] The cellulosic raw material in the present invention is not particularly limited as long as it is a material primarily composed of cellulose, and examples thereof include pulp, natural cellulose, regenerated cellulose, and fine cellulose obtained by depolymerizing a cellulose raw material through mechanical treatment. Commercially available products such as crystalline cellulose derived from pulp can be used as is as the cellulosic raw material. Alternatively, unused biomass containing a large amount of cellulose components, such as soybean pulp refuse or soybean hulls, may also be used as the raw material. When oxidizing the cellulosic raw material, the cellulosic raw material may be treated with an alkali of an appropriate concentration to facilitate penetration of the oxidizing agent into the raw pulp.

[0023] (carboxyl group amount) The carboxyl group content of the nanocellulose and oxidized cellulose of the present invention is preferably 0.20 mmol / g or more but less than 2.0 mmol / g. A carboxyl group content of 0.20 mmol / g or more can impart sufficient defibration properties to the oxidized cellulose. On the other hand, a carboxyl group content of less than 2.0 mmol / g can reduce the proportion of particulate cellulose and produce oxidized nanocellulose of uniform quality. From this perspective, the carboxyl group content of the nanocellulose and oxidized cellulose of the present invention is more preferably 0.35 mmol / g or more, even more preferably 0.40 mmol / g or more, even more preferably 0.42 mmol / g or more, still more preferably 0.50 mmol / g or more, even more preferably greater than 0.50 mmol / g, even more preferably 0.55 mmol / g or more, even more preferably 0.6 mmol / g or more, and particularly preferably 0.65 mmol / g or more. The upper limit of the carboxyl group content is more preferably 1.5 mmol / g or less, even more preferably 1.2 mmol / g, even more preferably 1.0 mmol / g or less, and even more preferably 0.9 mmol / g. A preferred range of the carboxyl group content can be determined by appropriately combining the above-mentioned upper and lower limits. The carboxyl group content of the oxidized cellulose is more preferably 0.35 to 2.0 mmol / g, even more preferably 0.35 to 1.5 mmol / g, even more preferably 0.40 to 1.5 mmol / g, even more preferably 0.50 to 1.2 mmol / g, even more preferably more than 0.50 to 1.2 mmol / g, and even more preferably 0.55 to 1.0 mmol / g.

[0024] 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 weak acid, where the change in electrical conductivity is gradual, after adding 0.1 M aqueous hydrochloric acid to an aqueous solution prepared by mixing oxidized cellulose with water to adjust the pH to 2.5, and then adding 0.05 N aqueous sodium hydroxide dropwise and measuring the electrical conductivity until the pH reaches 11.0. Details follow the method described in the Examples below. The amount of carboxy groups can be adjusted by changing the reaction time, reaction temperature, pH of the reaction solution, etc. of the oxidation reaction. Amount of carboxyl group = a (ml) x 0.05 / mass of oxidized cellulose (g)

[0025] The oxidized cellulose of the present invention can be obtained, for example, by oxidizing a cellulosic raw material under conditions in which the available chlorine concentration of hypochlorous acid or a salt thereof in the reaction system is relatively high (e.g., 14% to 43% by mass). The oxidized cellulose of the present invention can also be produced by appropriately controlling the reaction conditions, such as the available chlorine concentration, the pH during the reaction, and the reaction temperature. The oxidized cellulose thus obtained preferably has a structure in which at least two of the hydroxyl groups on the glucopyranose ring constituting the cellulose are oxidized. 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 carboxyl groups are introduced. Furthermore, it is preferable that the hydroxyl group at the sixth position on the glucopyranose ring in this nanocellulose is not oxidized and remains as a hydroxyl group. The position of the carboxyl group on the glucopyranose ring of oxidized cellulose is determined by the solid state. 13 It can be analyzed by C-NMR spectroscopy.

[0026] The above solid 13 The presence of an oxidized structure can be determined by observing peaks corresponding to the carboxyl groups at the second and third positions of the glucopyranose ring in a C-NMR spectrum. In this case, the peaks corresponding to the carboxyl groups at the second and third positions can be observed as broad peaks in the range of 165 ppm to 185 ppm. The broad peak here can be determined by the peak area ratio. That is, a baseline is drawn around the peak in the range of 165 ppm to 185 ppm in the NMR spectrum, the total area value is calculated, and then the area value is vertically divided at the peak top to calculate the ratio of the two peak area values ​​(large area value / small area value). If the ratio of the peak area values ​​is 1.2 or more, it can be said that the peak is broad. The presence or absence of the 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 more, it can be determined that a broad peak is present. The ratio L' / L may be 0.2 or more, 0.3 or more, 0.4 or more, or even 0.5 or more. There is no particular upper limit to the ratio L' / L, but it is usually 3.0 or less, and may be 2.0 or less, or 1.0 or less. In addition, the structure of the above-mentioned glucopyranose ring of this nanocellulose can also be determined by analysis in accordance with the method described in Sustainable Chem. Eng. 2020, 8, 48, 17800-17806.

[0027] Nanocellulose in the present invention is an aggregate of individual fibers. Nanocellulose in the present invention is sufficient as long as it contains at least one CNF, and it is preferable that CNF is the main component. Here, "CNF is the main component" means that the proportion of CNF in the 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.

[0028] The average fiber length of nanocellulose in the present invention is preferably 50 nm or more and 800 nm or less. If the average fiber length exceeds 800 nm, the dispersion containing nanocellulose tends to thicken. Also, if the average fiber length is less than 50 nm, the functionality of nanocellulose tends to be less apparent. The average fiber width of the nanocellulose in the present invention is not particularly limited, but is preferably 2.0 nm or more and 10.0 nm or less.

[0029] The average fiber length is preferably from 50 to 550 nm, more preferably from 50 to 500 nm, and even more preferably from 50 to 400 nm.The average fiber width is preferably from 2.0 to 8.0 nm, and more preferably from 2.5 to 6.0 nm.

[0030] In the nanocellulose of the present invention, the aspect ratio (average fiber length / average fiber width), which is the ratio of the average fiber width to the average fiber length, is preferably 20 or more and 200 or less. It is believed that the functionality of nanocellulose can be further enhanced by having an aspect ratio of 200 or less. From this perspective, the aspect ratio is more preferably 190 or less, and even more preferably 180 or less. On the other hand, if the aspect ratio is too low, i.e., if the nanocellulose is in the form of thick rods rather than elongated fibers, aggregation occurs due to uneven distribution, and dispersibility tends to decrease. Therefore, the aspect ratio is preferably 20 or more, more preferably 30 or more, and even more preferably 40 or more.

[0031] The average fiber width and average fiber length were calculated by mixing nanocellulose with water to a nanocellulose concentration of approximately 1 to 10 ppm, air-drying the resulting diluted cellulose aqueous dispersion on a mica substrate, observing the shape of the nanocellulose using a scanning probe microscope, randomly selecting any number of fibers from the obtained image, and calculating the cross-sectional height of the shape image = fiber width and the perimeter divided by 2 = fiber length. Image processing software can be used to calculate these average fiber widths and lengths. While the image processing conditions are arbitrary, differences in calculated values ​​may occur even for the same image depending on the conditions. The range of difference in values ​​depending on the conditions is preferably within ±100 nm for average fiber length. The range of difference in values ​​depending on the conditions is preferably within ±10 nm for average fiber width.

[0032] [Method of manufacturing nanocellulose] An example of a method for producing nanocellulose that can be used in the fiber material or composite material of the present invention is described below. Specifically, this method involves oxidizing a cellulosic raw material using hypochlorous acid or a salt thereof in the substantial absence of N-oxyl compounds to obtain oxidized cellulose (also referred to as step A), and then obtaining nanocellulose from the oxidized cellulose (also referred to as step B).

[0033] (Step A: Production of oxidized cellulose) Examples of hypochlorous acid or a salt thereof used for oxidizing a cellulosic raw material include hypochlorous acid water, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, and ammonium hypochlorite. Among these, sodium hypochlorite is preferred from the viewpoint of ease of handling.

[0034] One method for producing oxidized cellulose by oxidation of a cellulosic raw material is to mix the cellulosic raw material with a reaction solution containing hypochlorous acid or a salt thereof. The solvent contained in the reaction solution is preferably water, as it is easy to handle and is less likely to cause side reactions. In the oxidation, the amount of hypochlorous acid or its salt used is not particularly limited, but it is preferable to use hypochlorous acid or its salt with an available chlorine concentration of 6% by mass or more and 43% by mass or less. By using hypochlorous acid or its salt with an available chlorine concentration of 6% by mass or more and 43% by mass or less, the amount of carboxy groups in the oxidized cellulose can be sufficiently increased, allowing for sufficient pulverization, and making it possible to omit the mechanical fiberization treatment that follows the oxidation reaction. The available chlorine concentration of hypochlorous acid or a salt thereof in the reaction liquid (reaction system) is also preferably in the range of 6 to 43 mass %.

[0035] From the viewpoint of smoothly proceeding with the micronization of oxidized cellulose, the lower limit of the available chlorine concentration is more preferably 7% by mass or more, even more preferably 8% by mass or more, still more preferably 8.5% by mass or more, even more preferably 9% by mass or more, and even more preferably 14% by mass or more. Furthermore, from the viewpoint of suppressing excessive decomposition of cellulose, the available chlorine concentration of the reaction solution is more preferably 40% by mass or less, and even more preferably 38% by mass or less. The range of the available chlorine concentration of the reaction solution can be any combination of the above-mentioned lower and upper limits.

[0036] The available chlorine concentration of hypochlorous acid or its salts is defined as follows: Hypochlorous acid is a weak acid that exists as an aqueous solution, and hypochlorite is a compound in which the hydrogen of hypochlorous acid is replaced by another cation. For example, sodium hypochlorite, a hypochlorite, exists in a solvent (preferably in an aqueous solution), so the concentration is measured as the amount of available chlorine in the solution, not the concentration of sodium hypochlorite. Here, with regard to the available chlorine of sodium hypochlorite, the oxidizing power of the divalent oxygen atom generated by the decomposition of sodium hypochlorite is equivalent to two atomic equivalents of monovalent chlorine, so the bonded chlorine atoms of sodium hypochlorite (NaClO) have the same oxidizing power as two atoms of unbonded chlorine (Cl2), and the available chlorine = 2 × (chlorine in NaClO). The specific measurement procedure is as follows: First, the sample is precisely weighed, and water, potassium iodide, and acetic acid are added and left to stand. The liberated iodine is titrated with a sodium thiosulfate solution using a starch aqueous solution as an indicator to measure the available chlorine concentration.

[0037] The reaction in the nanocellulose production method may or may not be adjusted to any pH range, but it is recommended to adjust the pH to 5.0 or higher. Within this range, the oxidation reaction of the cellulosic raw material can proceed sufficiently, the amount of carboxy groups in the oxidized cellulose is sufficiently large, and pulverization by stirring tends to proceed easily. The pH of the reaction system is more preferably 7.0 or higher, and even more preferably 8.0 or higher. There is no particular upper limit to the pH of the reaction system, but it is preferably 14.5 or lower, more preferably 14.0 or lower, and even more preferably 13.0 or lower. The pH range of the reaction system is more preferably 7.0 to 14.0, and even more preferably 8.0 to 13.5.

[0038] During the reaction, the pH of the reaction system decreases as carboxyl groups are generated in the cellulosic raw material by the oxidation reaction. Therefore, from the viewpoint of efficiently progressing the oxidation reaction, it is preferable to add an alkaline agent (e.g., sodium hydroxide) or an acid (e.g., hydrochloric acid) to the reaction system and carry out the oxidation reaction while adjusting the pH of the reaction system.

[0039] Hereinafter, the method for producing oxidized cellulose will be further explained using as an example the case where sodium hypochlorite is used as hypochlorous acid or a salt thereof.

[0040] When oxidizing a cellulosic raw material using sodium hypochlorite, the reaction liquid is preferably a sodium hypochlorite aqueous solution. Methods for adjusting the effective chlorine concentration of a sodium hypochlorite aqueous solution to a target concentration (for example, a target concentration: in the range of 6% by mass to 43% by mass) include concentrating a sodium hypochlorite aqueous solution having an effective chlorine concentration lower than the target concentration, diluting a sodium hypochlorite aqueous solution having an effective chlorine concentration higher than the target concentration, and dissolving sodium hypochlorite crystals (for example, sodium hypochlorite pentahydrate) in a solvent. Among these, the method of diluting a sodium hypochlorite aqueous solution or dissolving sodium hypochlorite crystals in a solvent to adjust the effective chlorine concentration as an oxidizing agent is preferred because it causes less self-decomposition (i.e., less reduction in effective chlorine concentration) and is easy to adjust the effective chlorine concentration.

[0041] The method for mixing the cellulosic raw material with the aqueous sodium hypochlorite solution is not particularly limited, but from the viewpoint of ease of operation, it is preferable to add the cellulosic raw material to the aqueous sodium hypochlorite solution and mix them.

[0042] To efficiently promote the oxidation reaction of the cellulosic raw material, it is preferable to stir the mixture of the cellulosic raw material and the aqueous sodium hypochlorite solution during the oxidation reaction. Examples of stirring methods include a stirrer with a stirring blade, a homomixer, a disperser-type mixer, a homogenizer, and external circulation stirring. Among these, methods using one or more of shear-type stirrers such as homomixers and homogenizers, stirrers with a stirring blade, and a disperser-type mixer are preferred, as they allow the oxidation reaction of the cellulosic raw material to proceed smoothly and make it easy to adjust the degree of polymerization of the oxidized cellulose to a predetermined value or less. Methods using a stirrer with a stirring blade are particularly preferred. When using a stirrer with a stirring blade, devices equipped with known stirring blades such as propeller blades, paddle blades, turbine blades, swept-back blades, anchor blades, gate blades, Max Blend blades, Full Zone blades, helical ribbon blades, and screw blades (e.g., with a draft tube) can be used. Furthermore, when using a stirrer with a stirring blade, stirring is preferably performed at a rotation speed of 50 to 1,000 rpm. Furthermore, a multi-screw kneader such as a single-screw kneader or a twin-screw kneader can also be used.

[0043] The reaction temperature in the oxidation reaction is usually in the range of 15°C to 100°C. From the viewpoint of further accelerating the progress of the oxidation reaction, the reaction temperature is preferably 30°C or higher, more preferably over 30°C, even more preferably 31°C or higher, and even more preferably 35°C or higher. The higher the reaction temperature, the higher the viscosity tends to be, and the homogeneity of the reaction system tends to decrease. From the viewpoint of increasing the homogeneity of the reaction system and improving productivity, the reaction temperature is preferably 60°C or lower, more preferably 55°C or lower, and even more preferably 40°C or lower. The reaction time for the oxidation reaction can be set depending on the degree of progress of the oxidation, but is usually about 15 minutes to 50 hours. From the viewpoint of further accelerating the progress of the oxidation reaction, the reaction time is preferably 2 hours or more, more preferably more than 2 hours, and even more preferably 3 hours or more.

[0044] The pressure under which the reaction is carried out is not particularly limited, but is usually in the range of normal pressure to 1.0 MPaG (gauge pressure, the same applies hereinafter). Here, normal pressure means a pressure equal to atmospheric pressure. By carrying out oxidation under pressure, the amount of hypochlorous acid or a salt thereof used can be reduced, tending to enable more efficient production of oxidized cellulose. From the viewpoint of efficiency, the pressure is preferably 0.1 MPaG or more and 1.0 MPaG or less. In this case, the available chlorine concentration of hypochlorous acid or a salt thereof may be more than 0 mass% and 43 mass% or less, and from the viewpoint of increasing efficiency, it is preferably 0.1 mass% or more and 20 mass% or less, more preferably 1.0 mass% or more and 15 mass% or less, and even more preferably 1.0 mass% or more and 10 mass% or less.

[0045] In the production of oxidized cellulose, after the oxidization of the cellulosic raw material, a treatment to terminate the oxidation reaction may be carried out. The treatment to terminate the oxidation reaction is not particularly limited, but examples thereof include a method of adding an acid or a metal catalyst. Another preferred example is a method of reducing hypochlorous acid or a salt thereof. Specific examples of treatment to terminate the oxidation reaction include a method of adding a reducing agent such as sodium sulfite. The amount of reducing agent added may be adjusted appropriately depending on the amount of hypochlorous acid or a salt thereof (available chlorine concentration).

[0046] The solution containing oxidized cellulose obtained by the above reaction can be subjected to known isolation processes such as centrifugation and filtration, and further purified as necessary to obtain oxidized cellulose as an oxidation product of a cellulosic raw material with hypochlorous acid or a salt thereof. Furthermore, in the isolation process, some or all of the carboxy groups in the oxidized cellulose may be converted to the H-type (-COOH) by, for example, adjusting the pH of the solution containing oxidized cellulose to 4 or less. Furthermore, the solution containing oxidized cellulose obtained by the above reaction may be used as is, or may be subjected to the subsequent defibration step, for example.

[0047] (Reduction treatment process) The cellulose fibers after the oxidation treatment may be reduced with a reducing agent as needed. This reduces at least a portion of the aldehyde and ketone groups back to hydroxyl groups. Carboxy groups are not reduced. The total content of carbonyl groups (aldehyde and ketone groups) in the oxidized cellulose obtained by this reduction, calculated by the semicarbazide method described below, is preferably 0.3 mmol / g or less, more preferably 0.1 mmol / g or less. By keeping the carbonyl group content at 0.3 mmol / g or less, the decrease in molecular weight of nanocellulose is suppressed, and the thickening effect in solvents tends to be maintained for a long period of time. Note that if the carbonyl group content exceeds 0.3 mmol / g, aggregates tend to form during long-term storage, and the viscosity tends to decrease significantly over time. The reducing agent used in the reduction reaction can be a commonly used one, such as LiBH4, NaBH3CN, NaBH4, etc. Among these, NaBH4 is preferred from the viewpoints of cost and availability. The amount of the reducing agent may be in the range of 0.1 to 20% by mass based on the mass of oxidized cellulose. The reaction conditions may be at room temperature or slightly higher than room temperature for 10 minutes to 10 hours.

[0048] The total content of carbonyl groups (aldehyde and ketone groups) using the semicarbazide method is measured, for example, as follows. First, exactly 50 ml of a 3 g / L aqueous solution of semicarbazide hydrochloride, adjusted to pH 5 with phosphate buffer, is added to a dried sample, the container is sealed, and the mixture is shaken for two days. Next, exactly 10 ml of this solution is placed in a 100 ml beaker, to which 25 ml of 5 N sulfuric acid and 5 ml of 0.05 N potassium iodate aqueous solution are added, and the mixture is stirred for 10 minutes. Then, 10 ml of a 5% aqueous solution of potassium iodide is added, and the mixture is immediately titrated with 0.1 N sodium thiosulfate solution using an automatic titrator. The amount of carbonyl groups in the sample can be calculated from the titration amount and other data using the following formula. Semicarbazide reacts with aldehyde and ketone groups to form Schiff bases (imines), but does not react with carboxy groups. Therefore, the above measurement is thought to be able to quantify only the amount of carbonyl groups.

[0049] The oxidized cellulose is preferably in the form of a dispersion. The dispersion referred to here is a suspension containing oxidized cellulose. The dispersion may contain the solvent used during oxidation. Alternatively, a dispersion medium may be added as appropriate to form the dispersion. When the oxidized cellulose is in the form of a dispersion, it is easy to handle and tends to be more easily micronized. When the oxidized cellulose of the present invention is in the form of a dispersion, the amount of oxidized cellulose is typically in the range of 0.1% to 95% by mass, preferably 1% to 50% by mass, and more preferably 1% to 30% by mass, when the total amount of the dispersion is taken as 100% by mass.

[0050] Oxidized cellulose includes fibrous cellulose obtained by oxidizing a cellulosic raw material with hypochlorous acid or its salts. Oxidized cellulose is also called oxidized cellulose fiber. That is, oxidized cellulose includes an oxidation product of a cellulosic raw material with hypochlorous acid or its salts. Cellulose is the main component of plants, and bundles of cellulose molecules are called cellulose microfibrils. The cellulose in cellulosic raw materials is also contained in the form of cellulose microfibrils.

[0051] (Process B: Fiber defibration) Nanocellulose can be obtained by defibrating the oxidized cellulose obtained above into nano-sized particles as needed. Methods for defibrating oxidized cellulose include weak stirring using a magnetic stirrer or mechanical defibration.

[0052] Examples of mechanical defibration methods include methods using various mixing and stirring devices such as a screw mixer, paddle mixer, disperser mixer, turbine mixer, homomixer under high-speed rotation, high-pressure homogenizer, ultra-high-pressure homogenizer, double-cylinder homogenizer, ultrasonic homogenizer, water-flow opposing collision-type disperser, beater, disk refiner, conical refiner, double-disc refiner, grinder, single-shaft or multi-shaft kneader, planetary stirrer, vibration stirrer, etc. Nanocellulose can be produced by treating oxidized cellulose with one of these devices alone or in combination of two or more types, preferably in a dispersion medium, to nanosize the oxidized cellulose.

[0053] The defibration of oxidized cellulose can be preferably performed using an ultra-high-pressure homogenizer, as this method allows for the production of nanocellulose with a more advanced defibration process. When using an ultra-high-pressure homogenizer, the pressure during the defibration process is preferably 100 MPa or higher, more preferably 120 MPa or higher, and even more preferably 150 MPa or higher. The number of defibration processes is not particularly limited, but from the viewpoint of sufficiently progressing defibration, it is preferably two or more times, more preferably three or more times. Furthermore, the oxidized cellulose can be sufficiently defibrated by mild stirring using a planetary stirrer or a vibration stirrer. Examples of vibration stirrers include a vortex mixer (touch mixer). In other words, when using the oxidized cellulose, uniform nanocellulose can be obtained even when the defibration process is performed under mild defibration conditions.

[0054] The defibration treatment is preferably carried out in a state where the oxidized cellulose is mixed with a dispersion medium. The nanocellulose used in the present invention may also be in the form of a dispersion liquid in which it is dispersed in a dispersion medium.

[0055] The dispersion medium used for the oxidized cellulose or nanocellulose in the present invention is not particularly limited and can be selected appropriately depending on the purpose. Specific examples of the dispersion medium include water, alcohols, ethers, ketones, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, etc. As the dispersion medium, one of these may be used alone, or two or more may be used in combination.

[0056] Among the dispersion media, examples of alcohols include methanol, ethanol, isopropanol, isobutanol, sec-butyl alcohol, tert-butyl alcohol, methyl cellosolve, ethylene glycol, and glycerin. Examples of ethers include ethylene glycol dimethyl ether, 1,4-dioxane, and tetrahydrofuran. Examples of ketones include acetone and methyl ethyl ketone.

[0057] The dispersion medium of a dispersion containing oxidized cellulose or nanocellulose may be exchanged. The exchanged dispersion medium is preferably an alcohol-based dispersion medium, from the viewpoint of further improving the dispersibility of the nanocellulose obtained subsequently. Examples of alcohol-based dispersion mediums include the alcohols listed above. Although not particularly limited, the alcohol-based dispersion medium is preferably methanol. Examples of methods for exchanging the dispersion medium include centrifuging and decanting the dispersion, followed by adding the desired dispersion medium.

[0058] The nanocellulose in the present invention preferably satisfies the following zeta potential and light transmittance.

[0059] (zeta potential) The nanocellulose of the present invention preferably has a zeta potential of -30 mV or less. When the zeta potential is -30 mV or less (i.e., an absolute value of 30 mV or more), sufficient repulsion between microfibrils is obtained, making it easier to produce nanocellulose with a high surface charge density during mechanical defibration. This improves the dispersibility of the nanocellulose, and tends to result in excellent viscosity stability when made into a dispersion. When the zeta potential is -100 mV or higher (i.e., the absolute value is 100 mV or lower), oxidative scission in the fiber direction as oxidation progresses tends to be suppressed, making it possible to obtain nanocellulose of uniform size, and the functionality of the nanocellulose tends to be enhanced.

[0060] The zeta potential of the nanocellulose of the present invention is preferably -35 mV or less, more preferably -40 mV or less, and even more preferably -50 mV or less. The lower limit of the zeta potential is preferably -90 mV or more, more preferably -85 mV or more, even more preferably -80 mV or more, even more preferably -77 mV or more, even more preferably -70 mV or more, and even more preferably -65 mV or more. The range of the zeta potential can be appropriately combined with the above-mentioned lower and upper limits. The zeta potential is preferably -90 mV or more to -30 mV or less, more preferably -85 mV or more to -30 mV or less, even more preferably -80 mV or more to -30 mV or less, even more preferably -77 mV or more to -30 mV or less, even more preferably -70 mV or more to -30 mV or less, even more preferably -65 mV or more to -35 mV or less. In this specification, the zeta potential is a value measured at pH 8.0 and 20°C for a cellulose aqueous dispersion prepared by mixing nanocellulose with water to a nanocellulose concentration of 0.1% by mass. Specifically, it can be measured according to the following method. Add pure water to the aqueous dispersion of nanocellulose to dilute it to a nanocellulose concentration of 0.1%. Add 0.05 mol / L aqueous sodium hydroxide solution to the diluted aqueous dispersion of nanocellulose to adjust the pH to 8.0, and measure the zeta potential at 20°C using a zeta potential measuring device such as an Otsuka Electronics Zeta Potential Meter (ELSZ-1000).

[0061] (light transmittance) The nanocellulose of the present invention has few aggregates, and nanocellulose dispersions dispersed in a dispersion medium tend to have little light scattering from fine cellulose fibers and exhibit high light transmittance. Specifically, the nanocellulose of the present invention preferably has a light transmittance of 95% or more in a mixed solution when mixed with water to a solids concentration of 0.1% by mass. The light transmittance is more preferably 96% or more, and even more preferably 97% or more. The light transmittance is a value measured at a wavelength of 660 nm using a spectrophotometer. The light transmittance can also be measured using an aqueous dispersion containing nanocellulose. Specifically, it can be measured according to the following method. The aqueous dispersion of nanocellulose is placed in a 10 mm thick quartz cell, and the light transmittance at a wavelength of 660 nm is measured using a spectrophotometer such as the JASCO V-550.

[0062] The zeta potential and light transmittance can be controlled by oxidation using hypochlorous acid or its salts, particularly by adjusting the reaction time, reaction temperature, stirring conditions, etc. of the oxidation reaction. Specifically, as the reaction time and / or reaction temperature is increased, oxidation of the surface of cellulose microfibrils in the cellulosic raw material progresses, and the repulsion between fibrils due to electrostatic repulsion and osmotic pressure increases, tending to result in a smaller average fiber width. Furthermore, the zeta potential tends to be increased by setting one or more of the oxidation reaction time, reaction temperature, and stirring conditions (e.g., by increasing the reaction time) to promote oxidation (i.e., to increase the degree of oxidation).

[0063] The degree of polymerization of the oxidized cellulose used in the present invention is preferably 600 or less. If the degree of polymerization of oxidized cellulose exceeds 600, a large amount of energy tends to be required for defibration, making it impossible to exhibit sufficient easy defibration properties, which tends to result in a decrease in the dispersibility of the nanocellulose and ultimately a decrease in strength. From the perspective of easy defibration properties, no lower limit is set for the degree of polymerization of oxidized cellulose. However, if the degree of polymerization of oxidized cellulose is less than 50, the proportion of particulate cellulose rather than fibrous cellulose will be high, which may reduce the effectiveness of the nanocellulose. From the above perspective, the degree of polymerization of oxidized cellulose is preferably in the range of 50 or more and 600 or less.

[0064] The degree of polymerization of oxidized cellulose is more preferably 580 or less, even more preferably 560 or less, even more preferably 550 or less, still more preferably 500 or less, even more preferably 450 or less, and even more preferably 400 or less. From the viewpoint of improving the viscosity stability and coatability of the dispersion, the lower limit of the degree of polymerization is more preferably 60 or more, even more preferably 70 or more, even more preferably 80 or more, even more preferably 90 or more, even more preferably 100 or more, even more preferably 110 or more, and particularly preferably 120 or more. A preferred range of the degree of polymerization can be determined by appropriately combining the above-mentioned upper and lower limits. The degree of polymerization of oxidized cellulose is more preferably 60 to 600, even more preferably 70 to 600, even more preferably 80 to 600, even more preferably 80 to 550, even more preferably 80 to 500, even more preferably 80 to 450, and particularly preferably 80 to 400. The degree of polymerization of oxidized cellulose is the average degree of polymerization (viscosity average degree of polymerization) measured by a viscosity method. In detail, it can be measured according to the following method. Oxidized cellulose is added to an aqueous solution of sodium borohydride adjusted to pH 10, and reduced at 25°C for 5 hours. The amount of sodium borohydride is 0.1 g per 1 g of oxidized cellulose. After reduction, solid-liquid separation is performed by suction filtration, followed by washing with water, and the resulting oxidized cellulose is freeze-dried. 0.04 g of dried oxidized cellulose is added to 10 ml of pure water and stirred for 2 minutes, after which 10 ml of 1 M copper ethylenediamine solution is added to dissolve. The flow time of the blank solution and the flow time of the cellulose solution are then measured at 25°C using a capillary viscometer. The relative viscosity (η) is calculated from the flow time of the blank solution (t0), the flow time of the cellulose solution (t), and the concentration of oxidized cellulose (c [g / ml]) using the following equation: r ), specific viscosity (η sp ) and intrinsic viscosity ([η]) are determined sequentially, and the degree of polymerization (DP) of the oxidized cellulose is calculated using the viscosity measurement formula. η r =η / η0=t / t0 η sp =η r -1 [η]=η sp / (100×c(1+0.28η sp )) DP=175×[η]

[0065] The degree of polymerization of oxidized cellulose can be controlled by oxidation using hypochlorous acid or its salts. This can be achieved, in particular, by changing the reaction time, reaction temperature, pH, and effective chlorine concentration of hypochlorous acid or its salts during the oxidation reaction. Specifically, since increasing the degree of oxidation tends to decrease the degree of polymerization, methods for decreasing the degree of polymerization include increasing the oxidation reaction time and / or reaction temperature. Alternatively, the degree of polymerization of oxidized cellulose can be adjusted by changing the stirring conditions of the reaction system during the oxidation reaction. For example, under conditions where the reaction system is sufficiently homogenized using a stirring blade or the like, the oxidation reaction proceeds smoothly, and the degree of polymerization tends to decrease. On the other hand, under conditions where the reaction system is likely to be insufficiently stirred, such as stirring with a stirrer, the reaction tends to become non-uniform, making it difficult to sufficiently reduce the degree of polymerization of oxidized cellulose. Furthermore, the degree of polymerization of oxidized cellulose tends to vary depending on the selection of the raw cellulose. Therefore, the degree of polymerization of oxidized cellulose can also be adjusted by selecting the cellulosic raw material.

[0066] <Active energy ray curable monomer> The active energy ray curable monomer used in the present invention is not particularly limited as long as it is cured by active energy rays, and known active energy ray curable monomers can be used.Specifically, the above-mentioned monomer can be a compound having an ethylenically unsaturated group.Preferably, the above-mentioned ethylenically unsaturated group includes, for example, a (meth)acryloyl group, a vinyl group, and a vinyl ether group.

[0067] The compound having an ethylenically unsaturated group preferably has a hydrogen-bonding group in addition to the ethylenically unsaturated group, such as a hydroxyl group, a carboxyl group, an amide group, a carbamate group, an imide group, or a urea group.

[0068] Suitable examples of compounds having a hydroxyl group and an ethylenically unsaturated group include hydroxyl group-containing (meth)acrylates. The active energy ray-curable monomer of the present invention preferably contains at least a hydroxyl group-containing (meth)acrylate. Examples of the hydroxyl group-containing (meth)acrylate include: 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; 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; Examples include 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. The substitution position of the hydroxy group in the monomers such as the above-mentioned hydroxybutyl (meth)acrylate, hydroxypentyl (meth)acrylate, hydroxyhexyl (meth)acrylate, and hydroxyoctyl (meth)acrylate, which may have positional isomers, is optional. Among these compounds, hydroxybutyl (meth)acrylate is preferred. The hydroxybutyl (meth)acrylate is preferably 4-hydroxybutyl (meth)acrylate, and more preferably 4-hydroxybutyl acrylate.

[0069] Examples of compounds having a carboxy group and an ethylenically unsaturated group 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, and other carboxy group-containing (meth)acrylates.

[0070] Examples of compounds having an amide group and an ethylenically unsaturated group include N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, and (meth)acrylamide compounds. Specific examples of (meth)acrylamide compounds include N-alkylacrylamides such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and Nt-butyl(meth)acrylamide; N,N-dialkylacrylamides such as N,N-dimethyl(meth)acrylamide and N,N-diethyl(meth)acrylamide; N-alkoxyalkyl(meth)acrylamides such as N-hydroxyethyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, and N-methoxyethyl(meth)acrylamide; and (meth)acryloylmorpholine. Among these compounds, (meth)acryloylmorpholine is preferred. The (meth)acryloylmorpholine is preferably acryloylmorpholine.

[0071] Examples of compounds having a carbamate group and an ethylenically unsaturated group include (meth)acrylates having an oxazolidone group, and specific examples thereof include 2-(2-oxo-3-oxazolidinyl)ethyl (meth)acrylate.

[0072] Examples of compounds having an imide group and an ethylenically unsaturated group include compounds having a maleimide group. Examples of compounds having a maleimide group include (meth)acrylates having a hexahydrophthalimide group and (meth)acrylates having a tetrahydrophthalimide group. Specific examples of (meth)acrylates having a hexahydrophthalimide group include N-(meth)acryloyloxyethylhexahydrophthalimide. Examples of (meth)acrylates having a tetrahydrophthalimide group include N-(meth)acryloyloxyethyltetrahydrophthalimide.

[0073] The compound having an ethylenically unsaturated group used in the present invention may have two or more ethylenically unsaturated groups. When the compound has two or more ethylenically unsaturated groups, a compound having a urethane bond and two or more (meth)acryloyl groups (hereinafter also referred to as a urethane(meth)acrylate) can be preferably exemplified. Examples of the urethane (meth)acrylate include a reaction product of a polyol, an organic polyisocyanate, and a hydroxyl group-containing (meth)acrylate, and a reaction product of an organic polyisocyanate and a hydroxyl group-containing (meth)acrylate.

[0074] Examples of diols include low-molecular-weight diols, diols having a polyester skeleton, diols having a polyether skeleton, and diols having a polycarbonate skeleton. Examples of low-molecular-weight diols include ethylene glycol, propylene glycol, cyclohexanedimethanol, neopentyl glycol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol. Examples of diols having a polyester skeleton include esterification products of diol components such as the low-molecular-weight diols or polycaprolactone diols with acid components such as 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. Examples of polyether diols include polyethylene glycol, polypropylene glycol, and polyetramethylene glycol. Examples of polycarbonate diols include reaction products of the above-mentioned low molecular weight diols and / or bisphenols such as bisphenol A with ethylene carbonate and dialkyl carbonates such as dibutyl carbonate.

[0075] Examples of organic polyisocyanates include aliphatic polyisocyanates that do not have an alicyclic group (hereinafter also referred to as aliphatic polyisocyanates), aliphatic polyisocyanates that have an alicyclic group (hereinafter also referred to as alicyclic polyisocyanates), polyisocyanates that have a heterocycle, and aromatic polyisocyanates. Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate, tetramethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate. 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. An example of the polyisocyanate having a heterocycle is hexamethylene diisocyanate trimer. Examples of aromatic diisocyanates include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, paraphenylene diisocyanate, and 1,5-naphthalene diisocyanate.

[0076] Examples of the hydroxyl group-containing (meth)acrylate in the reaction product of a polyol, an organic polyisocyanate, and a hydroxyl group-containing (meth)acrylate, and the reaction product of an organic polyisocyanate and a hydroxyl group-containing (meth)acrylate, include compounds similar to the hydroxyl group-containing (meth)acrylate in the compound having a hydroxyl group and an ethylenically unsaturated group described above. The hydroxyl group-containing (meth)acrylate used in these reaction products may be a compound having a hydroxyl group and two or more (meth)acryloyl groups (hereinafter also referred to as a hydroxyl group-containing polyfunctional (meth)acrylate). The hydroxyl group-containing polyfunctional (meth)acrylate is not particularly limited, and examples thereof 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. In this specification, examples of alkylene oxide-modified polyolefins include ethylene oxide-modified polyolefins, propylene oxide-modified polyolefins, and ethylene oxide and propylene oxide-modified polyolefins.

[0077] The compound having an ethylenically unsaturated group used in the present invention may also be a compound having an ethylenically unsaturated group other than the above-mentioned compound having an ethylenically unsaturated group and compound having two or more ethylenically unsaturated groups (hereinafter also referred to as compound having other ethylenically unsaturated groups).

[0078] The other compounds having an ethylenically unsaturated group are not particularly limited, and examples thereof include: 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; (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; Alkoxyalkyl (meth)acrylates such as 2-methoxyethyl (meth)acrylate and 2-ethoxyethoxyethyl (meth)acrylate; (meth)acrylates having a heterocycle, such as tetrahydrofurfuryl (meth)acrylate and glycerin carbonate (meth)acrylate; (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; Examples thereof include (meth)acrylates such as glycidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and allyl (meth)acrylate.

[0079] In addition, as the compound having another ethylenically unsaturated group, a compound having two or more ethylenically unsaturated groups can be used. Specifically, a compound having two or more (meth)acryloyl groups can be mentioned, for example: Bifunctional (meth)acrylates having an aromatic skeleton, such as di(meth)acrylate of bisphenol A alkylene oxide adduct and bisphenol A di(meth)acrylate; 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; Hydroxypivalic acid neopentyl glycol di(meth)acrylate, hydroxypivalic acid neopentyl glycol ε-caprolactone-modified di(meth)acrylate; Bifunctional (meth)acrylates having an alicyclic skeleton such as dimethyloltricyclodecane di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, and spiroglycol di(meth)acrylate; and the like.

[0080] The active energy ray curable monomer used in the present invention can be appropriately selected from these compounds. As described above, it is preferable to use a hydroxyl group-containing (meth)acrylate as the active energy ray curable monomer. It is also preferable to use a compound having an amide group and an ethylenically unsaturated group as the active energy ray curable monomer. The hydroxyl group-containing (meth)acrylate is preferably the main component of the active energy ray-curable monomer that constitutes the active energy ray-curable composition. Here, "the hydroxyl group-containing (meth)acrylate is the main component" means that the mass ratio of the hydroxyl group-containing (meth)acrylate exceeds 50 parts by mass when the total amount of the active energy ray-curable monomer is 100 parts by mass. The mass ratio of the hydroxyl group-containing (meth)acrylate may be 55 parts by mass or more, 60 parts by mass or more, 65 parts by mass or more, or 70 parts by mass or more.

[0081] The content of nanocellulose (content as solids) in the active energy ray-curable composition of the present invention is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0.5 to 10 parts by mass, based on 100 parts by mass of the active energy ray-curable monomer. By having a nanocellulose content of 0.1 to 20 parts by mass, the curability of the composition is maintained while the strength of the cured product tends to be superior.

[0082] The active energy ray-curable composition of the present invention may contain a photopolymerization initiator, particularly when ultraviolet rays or visible light are used as the active energy rays. When the active energy ray-curable composition of the present invention is used as an electron beam-curable composition, it is possible to cure the composition by electron beam without adding a photopolymerization initiator. In this case, a small amount of a photopolymerization initiator can be added as needed to improve the curability. The photopolymerization initiator can be appropriately selected from known ones and used. Examples of the photopolymerization initiator include benzil dimethyl ketal, benzil, benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 1-hydroxycyclohexyl phenyl ketone (manufactured by IGM Resins BV, Omnirad184D), 2-hydroxy-2-methyl-1-phenylpropan-1-one (manufactured by IGM Resins BV, Omnirad1173), 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one (manufactured by IGM Resins BV, Omnirad2959), 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 (manufactured by IGM Resins BV, Omnirad2959), and the like. aromatic ketone compounds such as 2-methyl-1-[4-(methylthio)]phenyl]-2-morpholinopropan-1-one (IGM Resins BV, Omnirad127), 2-methyl-1-[4-(methylthio)]phenyl]-2-morpholinopropan-1-one (IGM Resins BV, Omnirad907), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one (IGM Resins BV, Omnirad369), and 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one (IGM Resins BV, Omnirad379); 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; 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; 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; acridone compounds such as acridone and 10-butyl-2-chloroacridone; 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); 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; and acridine derivatives such as 9-phenylacridine and 1,7-bis(9,9'-acridinyl)heptane; Examples include ADEKA Optoma N-1414 (manufactured by ADEKA Corporation), phenylglyoxylic acid methyl ester, ethyl anthraquinone, and phenanthrenequinone.

[0083] When the active energy ray-curable composition of the present invention contains a photopolymerization initiator, the content thereof is optional, but is usually in the range of 0.01 to 10 parts by mass, based on 100 parts by mass of the active energy ray-curable monomer. The content of the photopolymerization initiator is preferably in the range of 0.1 to 5 parts by mass, more preferably in the range of 0.5 to 3 parts by mass.

[0084] The active energy ray-curable composition of the present invention may appropriately contain other components such as additives that are typically used in active energy ray-curable compositions, such as plasticizers, polymerization inhibitors, antioxidants, light resistance improvers, cure shrinkage inhibitors such as polyfunctional mercaptans, and organic solvents.

[0085] <Method of producing active energy ray-curable composition> The active energy ray-curable composition of the present invention can be produced by appropriately mixing the components constituting the composition. That is, the active energy ray-curable composition of the present invention can be produced by blending nanocellulose and an active energy ray-curable monomer.

[0086] An example of a method for producing the active energy ray-curable composition of the present invention is a method comprising the step of blending an active energy ray-curable monomer with a nanocellulose dispersion dispersed in a dispersion medium. In this case, the monomer is preferably gradually added to the nanocellulose dispersion. For example, the monomer can be gradually added by adding it dropwise. The monomer is preferably added while heating and stirring the nanocellulose dispersion. The heating temperature can be adjusted appropriately depending on the type of dispersion medium, and is generally within the range of 20°C to 150°C. The dispersion medium contained in the nanocellulose dispersion may be removed as appropriate. Removal of the dispersion medium can be carried out, for example, by heating and stirring. That is, the method for producing an active energy ray-curable composition of the present invention includes a step of removing the dispersion medium from the nanocellulose dispersion by heating and stirring as appropriate. The heating temperature is preferably the temperature during heating and stirring described above.

[0087] In the method for producing the active energy ray-curable composition of the present invention, components other than the nanocellulose and the active energy ray-curable monomer (also referred to as other components) may be blended as needed. The other components may be blended in advance with the active energy ray-curable monomer or nanocellulose dispersion, or may be added to a blend of the active energy ray-curable monomer and nanocellulose.

[0088] The active energy ray-curable composition of the present invention can also be produced using oxidized cellulose, preferably hypooxidized cellulose. During the production of the active energy ray-curable composition, the hypooxidized cellulose can be defibrated in the composition by a dispersing or kneading operation, and at least a portion of the hypooxidized cellulose can become nanocellulose. Specifically, nanocellulose can be produced by blending hypooxidized cellulose with materials other than hypooxidized cellulose in the active energy ray-curable composition and defibrating the mixture by stirring, such as a dispersing or kneading operation, or by having the user defibrate the hypooxidized cellulose to nanosize. The stirring can be carried out by the method described above (Step B: Defibration Treatment).

[0089] One embodiment of the method for producing an active energy ray-curable composition of the present invention is a method for producing an active energy ray-curable composition containing nanocellulose and an active energy ray-curable monomer, which comprises a step of obtaining the active energy ray-curable composition by stirring a mixture containing oxidized cellulose and a material of the active energy ray-curable composition other than nanocellulose, wherein the oxidized cellulose comprises an oxide of a cellulose-based raw material with hypochlorous acid or a salt thereof, and is substantially free of N-oxyl compounds.

[0090] One preferred aspect of the present invention is a method for producing an active energy ray-curable composition containing nanocellulose and an active energy ray-curable monomer, the method comprising the steps of stirring oxidized cellulose and continuously adding materials other than nanocellulose to the active energy ray-curable composition to obtain the active energy ray-curable composition, wherein the oxidized cellulose comprises an oxide of a cellulose-based raw material with hypochlorous acid or a salt thereof, and is substantially free of N-oxyl compounds.

[0091] The material other than nanocellulose in the active energy ray-curable composition is any material that can be contained in the composition, and examples thereof include the above-mentioned active energy ray-curable monomers and photopolymerization initiators, but are not limited to these. As used herein, the phrase "continuously" and "mixed with the material" means that the micronization of oxidized cellulose by stirring and the mixing with the material are carried out as a series of operations. Specific modes of carrying out the stirring and mixing as a series of operations include, for example, a mode in which the material is added and mixed while the oxidized cellulose is stirred and micronized (one-pot operation), a mode in which the oxidized cellulose is stirred and micronized, and then the material is added and mixed (one-pot operation), and a mode in which the oxidized cellulose is stirred and micronized, and then the material is added and mixed (two-pot operation).

[0092] <Cured product> One aspect of the present invention is a cured product obtained by curing the active energy ray-curable composition of the present invention, i.e., a cured product of the active energy ray-curable composition. The use of the cured product of the present invention is not particularly limited, and the shape and form are selected depending on the use, etc. Examples of uses of the present invention include, but are not limited to, molding resins utilizing polymerization or crosslinking reactions, casting resins, stereolithography resins, sealants, dental polymerized resins, printing inks, printing varnishes, paints, photosensitive resins for printing plates, color proofs for printing, color filter resists, black matrix resists, photospacers for liquid crystal displays, rear projection screen materials, optical fibers, rib materials for plasma displays, dry film resists, resists for printed circuit boards, solder resists, semiconductor photoresists, resists for microelectronics, resists for manufacturing micromachine parts, etching resists, microlens arrays, insulating materials, hologram materials, optical switches, waveguide materials, overcoating agents, powder coatings, adhesives, pressure-sensitive adhesives, release agents, optical recording media, pressure-sensitive adhesives, release coating agents, compositions for image recording materials using microcapsules, and various devices.

[0093] The cured product of the present invention can be obtained by irradiating the active energy ray-curable composition of the present invention with active energy rays. When ultraviolet rays are used as the active energy rays, for example, an ultraviolet irradiation device can be used. Examples of light sources in the ultraviolet 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. The irradiation conditions such as the dose and irradiation intensity in the active energy ray irradiation may be appropriately set depending on the composition used, the substrate, the purpose, and the like. [Example]

[0094] EXAMPLES The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0095] (Method for measuring the average fiber length and width of nanocellulose) The nanocellulose dispersion was diluted 1,000 to 1,000,000 times with pure water, allowed to dry naturally on a mica substrate, and the shape of the nanocellulose was observed in AC mode using an Oxford Asylum scanning probe microscope "MFP-3D infinity." The obtained images were binarized using the image processing software "ImageJ" and analyzed for fiber length. For 100 or more fibers, the average fiber length was calculated as fiber length = "perimeter" ÷ 2. The fiber width was analyzed using the software included with the MFP-3D infinity. For more than 50 fibers, the average fiber width was calculated by taking the cross-sectional height of the shape image as the fiber width.

[0096] (Method for measuring the amount of carboxyl groups) To 60 ml of an oxidized cellulose aqueous dispersion, in which the concentration of oxidized cellulose fibers had been adjusted to 0.5% 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 carboxyl groups (mmol / g) was calculated using the following formula from the amount of sodium hydroxide (a) consumed in the neutralization stage of the weak acid, in which the change in electrical conductivity was gradual. Amount of carboxyl group = a (ml) x 0.05 / mass of oxidized cellulose fiber (g)

[0097] <Production Example 1: Production of nanocellulose> Pure water was added to a sodium hypochlorite aqueous solution with an effective chlorine concentration of 33% by mass and stirred to prepare 700 g of a solution with an effective chlorine concentration of 21% by mass. 35% by mass hydrochloric acid was added thereto and stirred to obtain a sodium hypochlorite aqueous solution with a pH of 11. The sodium hypochlorite aqueous solution was stirred at 200 rpm using a Shinto Scientific mixer (Three-One Motor, BL600) with a three-blade swept-back blade stirrer while being heated to 30°C in a constant-temperature water bath, and then 50 g of powdered pulp (VP-1) from TDI Corporation was added as a cellulosic raw material. After supplying the cellulosic raw material, the mixture was kept at 30°C in the same thermostatic water bath, and the pH during the reaction was adjusted to 11 by adding 48% by mass of sodium hydroxide, followed by stirring under the same conditions for 2 hours using a stirrer. After the reaction was completed, the purified oxidized cellulose was recovered by repeating centrifugation (1000 G, 10 minutes), decantation, and dispersion with the addition of pure water in an amount equivalent to the amount of the removed liquid. The amount of carboxyl groups was measured and found to be 0.70 mmol / g. Hydrochloric acid was then added to convert the carboxyl groups of the oxidized cellulose to the salt form (-COO - Na + ) to proton type (-COO - H + ) to obtain an aqueous dispersion with a pH of 2.5. The same amount of methanol was added to the dispersion, and the mixture was centrifuged (1000 G, 10 minutes) and decanted, followed by adding an amount of methanol equivalent to the amount of the removed liquid and dispersing again, and this process was repeated to recover oxidized cellulose (proton type) in which the dispersion medium had been changed from water to methanol. 20 g of a 2% methanol dispersion of the recovered oxidized cellulose was prepared and defibrated using a Hielscher UP-400S ultrasonic homogenizer under conditions of CYCLE 0.5 and AMPLITUDE 50 to obtain a 2% nanocellulose methanol dispersion. Observation under a scanning probe microscope revealed that the average fiber length was 230 nm and the average fiber width was 4 nm. The residual nitrogen content of nanocellulose derived from N-oxyl compounds was 1.0 ppm or less. The residual nitrogen content was measured as the amount of nitrogen using a trace total nitrogen analyzer (manufactured by Nitto Seiko Analytech Co., Ltd., device name: TN-2100H) and calculated as the increase from the raw pulp.

[0098] The available chlorine concentration in the aqueous sodium hypochlorite solution was measured by the following method. (Measurement of available chlorine concentration in sodium hypochlorite solution) 0.582 g of an aqueous solution of sodium hypochlorite pentahydrate crystals in pure water was precisely weighed, 50 ml of pure water was added, 2 g of potassium iodide and 10 ml of acetic acid were added, and the bottle was immediately sealed and left in a dark place for 15 minutes. After leaving it for 15 minutes, the liberated iodine was titrated with 0.1 mol / L sodium thiosulfate solution (indicator: starch TS), and the titer was found to be 34.55 ml. A blank test was performed separately to correct for this, and since 1 ml of 0.1 mol / L sodium thiosulfate solution corresponds to 3.545 mg Cl, the available chlorine concentration in the sodium hypochlorite aqueous solution was found to be 21% by mass.

[0099] In addition, the solid of the sample that was left for 24 hours or more at 23°C and 50% RH after freeze-drying the obtained oxidized cellulose 13 As a result of measuring C-NMR, it was confirmed that both compounds have a structure in which the hydroxyl groups at the second and third positions of the glucopyranose ring have been oxidized and carboxyl groups have been introduced. 13 The measurement conditions for C-NMR are as follows: (1) Sample tube: Zirconia tube (4 mm diameter) (2) Magnetic field strength: 9.4T (1H resonance frequency: 400MHz) (3) MAS rotation speed: 15 kHz (4) Pulse sequence: CPMAS method (5) Contact time: 3 ms (6) Waiting time: 5 seconds (7) Accumulation count: 10,000 to 15,000 times (8) Measuring device: JNM ECA-400 (manufactured by JEOL Ltd.) Furthermore, the fact that the oxidized cellulose obtained in Production Example 1 has a structure in which the hydroxyl groups at the second and third positions of the glucopyranose ring have been oxidized and carboxyl groups have been introduced was also confirmed by the results of measuring a model molecule of the oxidized cellulose as a sample using two-dimensional NMR. In addition, regarding the sixth place, solid cellulosic raw materials 13 C-NMR and solid state oxidized cellulose 13 Since no change was observed in the spectral data with C-NMR, it was determined that the hydroxyl group at position 6 was not oxidized and remained as a hydroxyl group in the oxidized cellulose.

[0100] [Example 1] 70 parts by weight of 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., hereinafter also referred to as 4-HBA) and 30 parts by weight of acryloylmorpholine (manufactured by KJ Chemicals Co., Ltd., hereinafter also referred to as ACMO) were blended. This blend was added dropwise in small amounts to 50 parts by weight of a 2% nanocellulose methanol dispersion heated and stirred at 60°C, and mixed. After continued heating and stirring, the methanol component in the liquid was evaporated and removed until it was 1% by weight or less. 0.3 parts of Omnirad184D (manufactured by IGM Resins BV, α-hydroxyalkylphenone) was mixed with the resulting liquid and stirred for 1 hour using a mix rotor to prepare an active energy ray-curable composition (also referred to as the composition of Example 1).

[0101] [Example 2] The composition of Example 2 was prepared by carrying out the same operation as in Example 1, except that the amount of 2% nanocellulose methanol dispersion used was changed from 50 parts by mass to 100 parts by mass.

[0102] [Example 3] The composition of Example 3 was prepared by carrying out the same operation as in Example 1, except that the amount of 2% nanocellulose methanol dispersion used was changed from 50 parts by mass to 200 parts by mass.

[0103] [Comparative Example 1] 70 parts of 4-HBA, 30 parts of ACMO, and 1 part of Omnirad184D were blended and stirred with a mix rotor for 1 hour to prepare a composition of Comparative Example 1.

[0104] The blending ratios of the components in the compositions obtained in the Examples and Comparative Examples are shown in Table 1.

[0105] [Table 1]

[0106] <Evaluation> (Preparation of cured product) Two glass plates (100 mm × 100 mm, 1 mm thick), two polyester films (100 mm × 100 mm, Lumirror T-62, manufactured by Toray Industries, Inc.), and one soft vinyl chloride sheet (1.0 mm thick) were used as molds for producing resin sheets. The polyester film was placed on the glass plates, and a soft vinyl chloride sheet mold cut into a No. 2 dumbbell shape was placed on top of that. The compositions obtained in the Examples and Comparative Examples were placed here, and a polyester film was placed on top of that, taking care not to trap bubbles. The glass plate was then placed on top of that and secured around the edges with clips. The resulting mold was irradiated with ultraviolet light to cure the composition. The ultraviolet light irradiation conditions were a conveyor-type ultraviolet light irradiation device (UB032-5B, high-pressure mercury lamp 60 W / cm) manufactured by Eye Graphics Co., Ltd., with an illuminance of approximately 2 W / cm. 2 The glass plate and PET film were then peeled off, and the cured product was taken out, and the front and back surfaces were irradiated with light for 2 minutes each, to obtain cured products from the compositions of the Examples and Comparative Examples.

[0107] (Tensile properties) Using the above cured product, an Instron 5566A was used, and the test was carried out at a jig distance of 20 mm, a pulling rate of 10 mm / min, and 23° C. The tensile strength (MPa) and elongation (%) of four test pieces were measured, and the weighted average values ​​were calculated.

[0108] (Tensile product) The tensile product is a property obtained by multiplying the tensile strength (MPa) by the elongation (%), and the larger this value, the tougher the cured product is. The values ​​obtained from the tensile property measurements were used for the tensile strength and elongation.

[0109] (viscoelastic spectrum) The cured product was used to measure the storage modulus E' at 100°C using a TA Instruments DMA850 viscoelasticity measuring device in tension mode at a frequency of 1 Hz and a heating rate of 2°C / min, and the storage modulus E' at 100°C was recorded.

[0110] The evaluation results are shown in Table 2.

[0111] [Table 2] [Industrial Applicability]

[0112] The active energy ray-curable composition of the present invention has industrial applicability in the fields of molding resins, casting resins, stereolithography resins, sealants, dental polymerized resins, printing inks, printing varnishes, paints, photosensitive resins for printing plates, color proofs for printing, color filter resists, black matrix resists, photospacers for liquid crystal displays, rear projection screen materials, optical fibers, rib materials for plasma displays, dry film resists, resists for printed circuit boards, solder resists, photoresists for semiconductors, resists for microelectronics, resists for manufacturing micromachine parts, etching resists, microlens arrays, insulating materials, hologram materials, optical switches, waveguide materials, overcoating agents, powder coatings, adhesives, pressure-sensitive adhesives, release agents, optical recording media, pressure-sensitive adhesives, release coating agents, compositions for image recording materials using microcapsules, and various devices.

Claims

1. An active energy ray-curable composition comprising nanocellulose and an active energy ray-curable monomer, The nanocellulose has a structure in which the hydroxyl groups at the second and third positions of the glucopyranose ring are oxidized and carboxyl groups are introduced, the active energy ray-curable monomer includes a compound having an ethylenically unsaturated group; Active energy ray-curable composition.

2. The carboxyl group content of the nanocellulose is 0.2 mmol / g or more and 2.0 mmol / g or less, The active energy ray-curable composition according to claim 1 .

3. The average fiber length of the nanocellulose is 50 nm or more and 800 nm or less. The active energy ray-curable composition according to claim 1 or 2.

4. The average fiber width of the nanocellulose is 2.0 nm or more and 10.0 nm or less, The active energy ray-curable composition according to any one of claims 1 to 3.

5. the active energy ray-curable monomer includes a hydroxyl group-containing (meth)acrylate; The active energy ray-curable composition according to any one of claims 1 to 4.

6. A cured product of the active energy ray-curable composition according to any one of claims 1 to 5.

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