Carbamate (meth)acrylate

Abstract

This invention provides a carbamate (meth)acrylate with excellent workability and, by hardening it, a hardened product with high tensile strength, excellent toughness, excellent shape recovery during bending, and excellent shape retention can be obtained. The carbamate (meth)acrylate of this invention is represented by the following formula (1), and its number average molecular weight (Mn) is 7500~60000. R 1-[OC(=O)NH-R 2] n…(1) (In formula (1), R 1 is an n-valent residue after removing the hydroxyl group from a polyol having n hydroxyl groups in one molecule, and n is 3 or more. The polyol is selected from polyether polyol, polyester polyol and polycarbonate polyol; the n R 2 in one molecule are each independently a residue after removing the isocyanate group from a monoisocyanate, which is a monoisocyanate having one or more (meth)acrylic acid groups in one molecule).

Description

Carbamate (meth)acrylate The present invention relates to carbamate (meth)acrylates suitable for coating agents, methods for manufacturing the same, curable compositions comprising the aforementioned carbamate (meth)acrylates, and cured products thereof. Methacrylates, when used as monomers, can yield functional polymers with excellent properties such as flexibility, toughness, impact resistance, and adhesion. Therefore, methacrylates are widely applicable compounds as monomers. One example of their use is as a component of surface protective coatings, which can prevent scratches or cracks on displays or touch panels of image display devices. The synthesis of carbamate (meth)acrylates generally involves reacting an isocyanate-terminated prepolymer with a compound having hydroxyl and (meth)acryloxy groups (e.g., 2-hydroxyethyl acrylate). The isocyanate-terminated prepolymer is prepared by reacting a polyol with a polyisocyanate in a molar ratio greater than 1 between the hydroxyl groups of the polyol and the isocyanate groups of the polyisocyanate. Alternatively, a known synthesis method involves reacting a polyol with a compound having isocyanate and (meth)acryloxy groups. The type of polyol used as a raw material for the carbamate (meth)acrylate obtained by these synthetic methods can significantly affect the properties of the cured product obtained by using the carbamate (meth)acrylate as a monomer. For example, Patent Document 1 describes a carbamate (meth)acrylate obtained by reacting an isocyanate-terminated prepolymer with 2-hydroxyethyl acrylate. This isocyanate-terminated prepolymer is synthesized using polypropylene glycol having three hydroxyl groups and a molecular weight of 4000-7000 (calculated by hydroxyl value). (Prior art documents, patent documents) Patent Document 1: Japanese Patent Application Publication No. 2018-35264 In addition, the invention aims to solve the problem that devices with structures that can be bent by their surfaces, such as flexible displays or foldable devices, require strength and shape recovery when bent. For example, urethane (meth)acrylate as described in Patent Document 1 can produce a hardened coating with high hardness, but its toughness and shape recovery when bent are not sufficient. The present invention was made in view of the above-mentioned situation, and its object is to provide a carbamate (meth)acrylate having a viscosity with excellent processability, and by hardening it, a hardened product with high tensile strength, toughness, excellent shape recovery and shape retention during bending can be obtained. The present invention is based on the following discovery that a hardened product obtained by means of a carbamate (meth)acrylate having a composition derived from a predetermined polyol has low residual strain, good toughness and shape recovery during bending, and excellent shape retention. The present invention provides the following means. [1] A carbamate (meth)acrylate, represented by the following formula (1), and having a number average molecular weight (Mn) of 7500 to 60000; R 1 -[OC(=O)NH-R 2 ] n …(1) In equation (1), R 1 This refers to the n-valent residues remaining after removing the hydroxyl groups from a polyol having n hydroxyl groups in one molecule, where n is 3 or more. The polyol is selected from polyether polyols, polyester polyols, and polycarbonate polyols; the n R... 2 Each is a residue after the isocyanate group has been removed from the monoisocyanate, wherein the monoisocyanate has one or more (meth)acryloxy groups in one molecule. [2] The carbamate (meth)acrylate of [1] has a weight average molecular weight (Mw) to number average molecular weight (Mn) ratio (Mw / Mn) of 1.0 to 1.4. [3] The carbamate (meth)acrylate of [1] or [2], wherein the aforementioned n is 4 to 10. [4] The carbamate (meth)acrylate of any one of [1] to [3] is the carbamate esterification product of the aforementioned polyol having n hydroxyl groups in one molecule and the aforementioned monoisocyanate; and the aforementioned polyol having n hydroxyl groups in one molecule has a molecular weight of 7500 or more when converted by hydroxyl value. [5] The carbamate (meth)acrylate of any one of [1] to [4], wherein the aforementioned polyol having n hydroxyl groups in one molecule is a polyether polyol. [6] The carbamate (meth) acrylate of any one of [1] to [5], wherein the aforementioned polyether polyol has an oxyalkylene group as a structural unit, and of the total oxyalkylene group, oxypropylene is 50% or more by mass of 100% by mass. [7] A method for manufacturing a carbamate (meth)acrylate involves obtaining a reaction product by reacting 1 mole of a polyol having n hydroxyl groups in one molecule with n moles of monoisocyanate through a carbamate esterification reaction; the aforementioned carbamate (meth)acrylate is represented by the following formula (1), and its number average molecular weight (Mn) is 7500~60000: R 1 -[OC(=O)NH-R 2 ] n …(1) In equation (1), R 1 This refers to the n-valent residues remaining after removing the hydroxyl groups from a polyol having n hydroxyl groups in one molecule, where n is 3 or more. The polyol is selected from polyether polyols, polyester polyols, and polycarbonate polyols; the n R... 2 Each is a residue after the isocyanate group has been removed from the monoisocyanate, wherein the monoisocyanate has one or more (meth)acrylic acid groups in one molecule. [8] The method for manufacturing carbamate (meth)acrylate as in [7], wherein the molecular weight of the polyol having n hydroxyl groups in one molecule is 7500 or more when converted by hydroxyl value. [9] The method for manufacturing carbamate (meth)acrylate as in [7] or [8], wherein the polyol having n hydroxyl groups in one molecule is a polyether polyol.

[10] The method for manufacturing carbamate (meth)acrylate as in any one of [7] to [9], wherein the polyether polyol has an oxyalkylene group as a structural unit, and of 100% by mass of total oxyalkylene groups, oxypropylene groups account for 50% by mass or more.

[11] A curable composition comprising any one of [1] to [6] a carbamate (meth)acrylate.

[12] A curable composition of

[11] wherein the content of the carbamate (meth)acrylate in the aforementioned curable composition is 50% by mass or more.

[13] A curable composition of

[11] or

[12] is a coating agent.

[14] A curable material formed by curing any one of

[11] to

[13] .

[15] An article comprising a curable material of

[14] . Effects of the Invention According to the present invention, a carbamate (meth)acrylate is provided, which has a viscosity with excellent workability, and by curing it, a cured product with high tensile strength, excellent toughness, excellent shape recovery upon bending, and excellent shape retention can be obtained. Therefore, the carbamate (meth)acrylate of the present invention can be effectively used in applications such as surface protective coatings for flexible displays or foldable devices. The definitions and meanings of the terms and symbols used in this specification are shown below. "(Meth)acryloxy" is a general term for acryloxy and methacryloxy. Similarly, "(meth)acrylic acid" is a general term for acrylic acid and methacrylic acid, while "(meth)acrylate" is a general term for acrylate and methacrylate. The number average molecular weight (Mn) and weight average molecular weight (Mw) are molecular weights converted to polystyrene obtained by gel permeation chromatography (GPC) based on a calibration curve prepared using standard polystyrene samples. "Molecular weight converted to hydroxyl value" is calculated using the formula 56100 × (number of hydroxyl groups in one molecule) / (hydroxyl value [mgKOH / g]). The hydroxyl value is determined according to JIS K 1557:2007. Viscosity is measured at 25°C using an E-type viscometer. The "NCO index" is a percentage representing the equivalent ratio of the isocyanate group to the hydroxyl group of the polyol in an isocyanate compound. [Carbamate (Meth)acrylate] The carbamate (meth)acrylate of the present invention is represented by the following formula (1), and Mn is 7500~60000. R 1 -[OC(=O)NH-R 2 ] n …(1) In equation (1), R 1 This refers to the n-valent residues remaining after removing the hydroxyl groups from a polyol molecule containing n hydroxyl groups, where n is 3 or more. The polyol is selected from polyether polyols, polyester polyols, and polycarbonate polyols. The n R groups in one molecule... 2 Each is a residue after the isocyanate group has been removed from the monoisocyanate, which is a molecule containing one or more (meth)acryloxy groups. We believe that the aforementioned carbamate (meth)acrylate has a backbone derived from a higher molecular weight polyol than previously thought, and a narrow molecular weight distribution. Therefore, cured products obtained by using it as a monomer easily form a uniform cross-linked network. Consequently, even at high molecular weight, the viscosity remains low and the processability is excellent, resulting in cured products with high tensile strength, high storage shear modulus, low residual strain, excellent toughness, and excellent shape recovery and shape retention during bending. The carbamate (meth)acrylate of the present invention is a compound represented by the aforementioned formula (1). From the viewpoint of rapid polymerization, the carbamate (meth)acrylate is preferably a carbamate acrylate. (R 1 In equation (1), R 1The term refers to the n-valent residues remaining after removing the hydroxyl groups from a polyol having n hydroxyl groups in one molecule, where n is 3 or more. This polyol is selected from polyether polyols, polyester polyols, and polycarbonate polyols. When the polyol is composed of multiple types, n is the average number of hydroxyl groups in one molecule calculated from the content ratio of each polyol. The polyol has 3 or more hydroxyl groups in one molecule, preferably 4 to 10, and more preferably 4 to 8. Cured products formed from urethane (meth)acrylates having a backbone derived from polyols with the aforementioned number of hydroxyl groups form a high-density cross-linked network, easily achieving good shape retention. Furthermore, by having 4 or more hydroxyl groups, it is easy to obtain cured products formed from urethane (meth)acrylates with high storage shear modulus, high tensile strength, and high surface hardness, and the surface of the cured product is less prone to damage. Moreover, cured products formed from urethane (meth)acrylates having a backbone derived from polyols with 10 or fewer hydroxyl groups exhibit improved shape stability. From the perspective that the cured product obtained by means of carbamate (meth)acrylate has better shape recovery when bent, polyether polyol is preferable. <Polyether Polyols> Polyether polyols are preferably polymers having three or more hydroxyl groups and alkyl groups as structural units. Polyether polyols can be obtained by ring-opening polymerization of compounds with cyclic ether structures onto initiators having three or more active hydrogen atoms. Alternatively, commercially available products can be used. Polyether polyols can be a single type or two or more types. The oxyalkylene group is preferably a straight-chain or branched alkylene group containing 1 to 14 carbon atoms, with 2 to 4 carbon atoms being more preferred. The oxyalkylene group can be a single type or can contain two or more types. Specifically, the oxyalkylene group is preferably selected from oxyethyl, oxypropyl, and oxytetramethylene, and oxypropyl is more preferred. From the viewpoint of good toughness of the cured carbamate (meth)acrylate, oxypropyl should preferably be 50% by mass or more of 100% by mass of total oxyalkylene groups, more preferably 60 to 100% by mass, more preferably 80 to 100% by mass, and even more preferably 100% by mass. Furthermore, the content ratio of oxypropyl in the total oxyalkylene group is considered to correspond to the following: in the synthesis of polyether polyols, the blending mass of propylene oxide relative to 100 parts by mass of the total blending amount of the source raw materials constituting the oxyalkylene group. Compounds having a cyclic ether structure include, for example: ethylene oxide, propylene oxide, 1,2-butene oxide, 2,3-butene oxide, methyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, lauryl glycidyl ether, hexyl glycidyl ether, and tetrahydrofuran. Among these, ethylene oxide and propylene oxide are preferred. Initiators containing active hydrogen groups can include, for example, hydroxyl, carboxyl, and amine groups with hydrogen atoms bonded to nitrogen atoms. Among these, hydroxyl groups are preferred, and alcoholic hydroxyl groups are more preferred. Initiators with three or more active hydrogen groups can include, for example, glycerol, trimethylolpropane, trimethylolpropane, 1,2,6-hexanetriol, neopentyl terephthalol, dipropylene glycol, dinepentyl terephthalol, sorbitol, sucrose, polyoxyalkylene polyols (polyoxyalkylene ethylene polyols, polyoxyalkylene propylene polyols), triethanolamine, and other polyols; and amines such as ethylenediamine and diethylenetriamine. Among these, polyols are preferred, polyoxyalkylene polyols are more preferred, and polyoxyalkylene propylene polyols are even more preferred. Initiators with three or more active hydrogen groups can be a single type or two or more types. The initiator may also include glycols. Examples of glycols include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butanediol, 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, triethylene glycol, tripropylene glycol, and polyoxyalkylene glycol. The glycol used in conjunction with an initiator having three or more active hydrogens may be a single type or two or more types. When an initiator having three or more active hydrogens includes a glycol, it is preferable to combine an initiator having four or more active hydrogens with the aforementioned glycol in such a way that n in the aforementioned formula 1 of the carbamate acrylate is three or more. Examples of initiators having four or more active hydrogens include neopentyl tertrol, dinepentyl tertrol, sorbitol, and sucrose. Ring-opening polymerization can be carried out using known catalysts such as potassium hydroxide, transition metal compound-porphyrin complex catalysts (e.g., complexes obtained by reacting organoaluminum compounds with porphyrins), complex metal cyanide complex catalysts, and catalysts composed of phosphonium olefin compounds. Among these catalysts, complex metal cyanide complex (DMC) catalysts are preferable in terms of obtaining polyether polyols with a narrow molecular weight distribution. Known compounds can be used for complex metal cyanide complexes, such as zinc hexacyanocobaltate complexes with terbutanol as a coordinating group. The production of polyether polyols by ring-opening polymerization using DMC catalyst can be carried out by known methods, such as those described in International Publication No. 2003 / 062301, International Publication No. 2004 / 067633, Japanese Patent Application Publication No. 2004-269776, Japanese Patent Application Publication No. 2005-15786, International Publication No. 2013 / 065802, and Japanese Patent Application Publication No. 2015-10162. <Polyester Polyols> Polyester polyols can be obtained, for example, by known manufacturing methods such as the polymerization and condensation of polyols containing polyols with three or more functions with diacids. Alternatively, commercially available products can also be used. Examples of dicarboxylic acids include: aliphatic dicarboxylic acids such as succinic acid, adipic acid, maleic acid, and fumaric acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and p-phthalic acid, as well as their anhydrides. A dicarboxylic acid can be a single type or two or more types. Among the polyols used in the manufacture of polyester polyols, polyols with three or more functionalities can be listed as follows: glycerol, trimethylolpropane, trimethylolpropane, 1,2,6-hexanetriol, neopentyl terephthalol, dipropylene glycol, dinepentyl terephthalol, sorbitol, sucrose, and polyoxyalkylene polyols (polyoxyalkylene ethylene polyol, polyoxyalkylene propylene polyol). A single polyol with three or more functionalities can be used, or there can be two or more types. Polyols used as raw materials for polyester polyols may also include glycols, such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butanediol, 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, triethylene glycol, tripropylene glycol, and polyoxyalkylene glycol. Glycols used in combination with polyols with three or more functionalities can be single or two or more types. When a polyol contains glycol, it is preferable to use it in combination with a polyol of four or more functions in such a way that n in the aforementioned formula (1) of the carbamate acrylate is three or more. Examples of polyols of four or more functions include neopentyl tertrol, dinepentyl tertrol, sorbitol, and sucrose. <Polycarbonate polyols> Polycarbonate polyols can be obtained, for example, by a manufacturing method known as described in Japanese Patent Application Publication No. 2021-59722, such as the polycondensation of a polyol containing three or more functional groups with a carbonate compound. Alternatively, commercially available products can also be used. Specific examples of polyols used in the manufacture of polycarbonate polyols can be those that are the same as those used in the manufacture of the aforementioned polyester polyols. A polyol with three or more functionalities can be a single type or two or more types. A glycol used in combination with a polyol with three or more functionalities can be a single type or two or more types. Examples of carbonate compounds include: dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, diphenyl carbonate, ethyl carbonate, trimethylolpropene carbonate, propylene carbonate, 1,2-butenyl carbonate, and neopentyl carbonate. A carbonate compound may be a single compound or two or more compounds. (R 2 In equation (1), n ​​R 2 Each is a residue after the isocyanate group has been removed from the monoisocyanate, which is a monoisocyanate having one or more (meth)acrylic acid groups in one molecule. R 2 and R 3They can be the same or different. From the perspective of efficiently synthesizing carbamate (meth)acrylates, R 2 and R 3 The same should be preferred. <Monoisocyanates> Monoisocyanates having a (meth)acryloxy group are preferably compounds having one or more (meth)acryloxy groups bonded to a hydrocarbon skeleton having an isocyanate group. There may be one or two or more (meth)acryloxy groups. The hydrocarbon skeleton is preferably an aliphatic or alicyclic hydrocarbon group. The aliphatic or alicyclic hydrocarbon group preferably has 8 or fewer carbon atoms, more preferably 2 to 6, and even more preferably 2 to 4. Examples of monoisocyanates containing a (meth)acrylic oxy group include: isocyanate-based meth(meth)acrylate, 2-isocyanate-based ethyl(meth)acrylate, and other compounds having one (meth)acrylic oxy group; and 1,1-(bis(meth)acrylic oxymethyl)ethyl isocyanate, 1,1-(bis(meth)acrylic oxymethyl)propyl isocyanate, and other compounds having two (meth)acrylic oxy groups. Commercially available examples include "Karenz AOI" (2-isocyanate-based ethyl acrylate), "Karenz MOI" (2-isocyanate-based ethyl methacrylate), and "Karenz BEI" (1,1-(bisacrylic oxymethyl)ethyl isocyanate) (all manufactured by Showa Denko Co., Ltd.). The molecular weight (Mn) of carbamate (meth)acrylate is 7500~60000, preferably 8000~55000, and more preferably 8500~50000. If Mn is within the above range, the cured carbamate (meth)acrylate will have high tensile strength, excellent toughness, excellent shape recovery and shape retention during bending. Furthermore, the Mw / Mn ratio should ideally be 1.0~1.4, more preferably 1.02~1.38, and even more preferably 1.05~1.25. Mw / Mn is an indicator of the dispersion (breadth) of the molecular weight distribution. An Mw / Mn ratio of 1 indicates monodispersity, and the closer to 1, the narrower the molecular weight distribution. If the molecular weight distribution is within the above range, even if the urethane (meth)acrylate has more than three (meth)acrylic acid groups per molecule and a high molecular weight of Mn of 7500 or higher, the viscosity remains low, resulting in good handling properties for curing components during mixing and other operations. Furthermore, the cured urethane (meth)acrylate exhibits low residual strain, readily forms a uniform cross-linked network, high tensile strength, excellent toughness and shape recovery during bending, and superior shape retention. (Viscosity) From the point of view of ease of handling, carbamate (meth)acrylate is a liquid at room temperature (25°C), and its viscosity at 25°C is preferably below 50 Pa·s, more preferably below 40 Pa·s, and even more preferably below 30 Pa·s. (Carbamate Reaction) The carbamate (meth)acrylate of the present invention is obtained by carbamate reaction of 1 mole of a polyol having n hydroxyl groups in 1 molecule with n moles of monoisocyanate. That is, the carbamate (meth)acrylate is derived from R in formula (1). 1 A polyol having n hydroxyl groups in one molecule and derived from R 2 The reaction product of monoisocyanate. From the viewpoint that the Mn of carbamate (meth)acrylate is within the above range, the molecular weight of the aforementioned polyol, converted by hydroxyl value, should preferably be 7500 or above, more preferably 8000 to 60000, and even more preferably 8500 to 55000. Carbamate reactions can be carried out using known methods, typically involving a mixture of polyols and monoisocyanates, under nitrogen or an inert gas atmosphere using a carbamate catalyst. Examples of carbamate catalysts include: organotin compounds such as dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dioctyltin dicaprate, and tin 2-ethylhexanoate; iron compounds such as ferric acetone and ferric chloride; lead compounds such as lead 2-ethylhexanoate; bismuth compounds such as bismuth 2-ethylhexanoate; and tertiary amines such as triethylamine and triethylenediamine. Among these, organotin compounds, lead 2-ethylhexanoate, and bismuth 2-ethylhexanoate are preferred. A single carbamate catalyst can be used, or two or more can be used in combination. The amount of carbamate catalyst used relative to 100 parts by mass of the polyol reactants should preferably be 0.001 to 1 part by mass, more preferably 0.002 to 0.5 parts by mass, and even more preferably 0.005 to 0.1 parts by mass. The reaction temperature for carbamate esterification should preferably be set at 20 to 100°C, more preferably 30 to 90°C, and even more preferably 40 to 80°C. [Curing Composition] The curing composition of the present invention comprises the above-described carbamate (meth)acrylate of the present invention. A polymerization initiator and other components may be blended into the curing composition as needed. From the viewpoint of obtaining a cured product with excellent toughness, the content of carbamate (meth)acrylate in the curing composition is preferably 50% by mass or more, more preferably 70% by mass or more and less than 100% by mass, and more preferably 80% by mass or more and less than 100% by mass. The blended components in the curing composition should be uniformly mixed, for example, using known mixing devices such as a rotary stirring degassing device, a homogenizer, a planetary mixer, a three-roll mill, or a bead mill. The blended components may be mixed simultaneously or by adding them sequentially. (Polymerization Initiator) The polymerization initiator should preferably be a free radical polymerization initiator, which can be either a photopolymerization initiator or a thermal polymerization initiator, and can be any known type. From the viewpoint of ease of controlling the polymerization reaction, a photopolymerization initiator should preferably be irradiated by ultraviolet light with a wavelength of less than 380 nm; and a thermal polymerization initiator should preferably be irradiated by heating in the range of 50 to 120°C. Examples of photopolymerization initiators include: 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methylphenylacetone, diethoxyacetophenone, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropanone, 1-(4-dodecylphenyl)-2-hydroxy-2-methylpropanone, 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl) ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morphofolinylacetone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin phenyl ether, benzyl dimethyl ketal, diphenyl ketone, benzoic acid, methyl benzoate, 4-phenyldiphenyl ketone-4-methoxydiphenyl ketone, 9-oxothiophene. 2-Chloro-9-oxysulfur 2-Methyl-9-oxosulfur 2,4-Dimethyl-9-oxosulfur Isopropyl 9-Oxysulfur 2,4-Dichloro-9-oxosulfur 2,4-Diethyl-9-oxosulfur 2,4-Diisopropyl-9-oxosulfur 2,4,6-Trimethylbenzoyldiphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, methyl phenylglyoxylate, benzil, and camphorquinone. A single photopolymerization initiator can be used, or two or more can be used in combination. Examples of thermal polymerization initiators include: azo compounds; organic peroxides such as hydrogen peroxide, dialkyl peroxides, peroxide esters, diacyl peroxides, peroxydicarbonates, peroxyketals, and peroxide ketals. Specific examples include: azobisisobutyronitrile, benzoyl peroxide, tributylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di(2-ethylhexyl)peroxyhexane, tributylperoxybenzoate, and tributylperoxybenzoate. Oxides, cumene hydroperoxide, diisopropylphenyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-dibutylperoxyhexane, 2,4-dichlorobenzoyl peroxide, 1,4-bis(2-tert-butylperoxyisopropyl)benzene, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, methyl ethyl ketone peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate. A single thermal polymerization initiator can be used, or two or more can be used in combination. From the viewpoint of a moderate polymerization rate, the content of polymerization initiator in the curing component should preferably be 0.001 to 20 parts by mass relative to 100 parts by mass of carbamate (meth)acrylate, more preferably 0.01 to 10 parts by mass, and even more preferably 0.1 to 7 parts by mass. When curing a component by irradiating it with light to obtain a cured product, the light source can be appropriately set according to the light absorption energy of the photopolymerization initiator. For example, the following devices can be used as the light source: ultraviolet light-emitting diodes (LEDs), low-pressure mercury lamps, high-pressure mercury lamps, mercury-xenon lamps, metal halide lamps, tungsten filament lamps, arc lamps, excimer lamps, excimer lasers, semiconductor lasers, YAG lasers, laser systems combining lasers and nonlinear optical crystals, and high-frequency induced ultraviolet light generating devices. The cumulative light intensity is set, for example, to 0.01~50 J / cm². 2 From the perspective of further stabilizing the physical properties of the hardened material, further heat treatment can be performed after light irradiation. The heating temperature is typically set at around 40~200℃, and the heating time is set at around 1 minute to 15 hours. Furthermore, by allowing the hardened material to stand at room temperature (around 15~25℃) for 1~48 hours, the physical properties of the hardened material can also be stabilized. When heat-treating a hardening component to obtain a hardened product, the heating temperature is typically set at around 40~250℃, and the heating time is typically set at around 5 minutes to 24 hours. Higher heating temperatures require shorter heating times, while lower heating temperatures require longer heating times. (Other Components) For good processability or intended use, the curing composition may contain other components besides carbamate (meth)acrylate and polymerization initiator. Examples of other components include: monomers other than the carbamate (meth)acrylate of this invention, catalysts, colorants such as pigments or dyes, silane coupling agents, tackifying resins, antioxidants, light stabilizers, metal deactivators, rust inhibitors, anti-aging agents, hygroscopic agents, anti-hydrolysis agents, defoamers, and fillers. Solvents may also be included. These other components in the curing composition may be blended in amounts that do not impair the effects of this invention. Other monomeric components are compounds that can copolymerize with carbamate (meth)acrylates, such as carbamate (meth)acrylates other than the carbamate (meth)acrylates of this invention, alkyl (meth)acrylates, hydroxyl-containing (meth)acrylates, amino-containing (meth)acrylates, and other (meth)acrylates. Other monomeric components may be a single type or two or more types may be used together. The curable composition containing the carbamate (meth)acrylate of the present invention is suitable for coating various substrates, including surface protective coatings to prevent scratches or cracks on displays or touch panels of image display devices. In particular, the cured product of this curable composition exhibits high tensile strength, excellent toughness, and excellent shape recovery and shape retention upon bending, thus making it suitable as a surface protective coating for flexible displays or foldable devices. [Curing Material] The curing material of the present invention is formed by curing a curable composition comprising the above-mentioned carbamate (meth)acrylate. It exhibits high tensile strength and storage shear modulus, low residual strain, excellent toughness, and excellent shape recovery and shape retention upon bending. Therefore, according to the present invention, these properties can be utilized in the applications described above, thereby making it suitable to provide coatings incorporating the curing material of the present invention, and particularly suitable to provide articles such as flexible displays or foldable devices having a coating surface formed by the curing material of the present invention. The present invention will be specifically described below with reference to the embodiments. However, the present invention is not limited to the following embodiments and various modifications can be made without departing from the spirit of the present invention. [Raw Material Compounds] The details of the various raw material compounds used in the examples are as follows. • DMC-TBA: Zinc hexacyanocobaltate-tert-butanol complex • Initiator A: Polyoxypropylene tetraol (molecular weight 1200 in hydroxyl value) obtained by ring-opening polymerization of propylene oxide (hereinafter referred to as "PO") with neopentyl tert-ol • Initiator B: Polyoxypropylene hexaol (molecular weight 880 in hydroxyl value) obtained by ring-opening polymerization of PO with sorbitol • Initiator C: Polyoxypropylene triol (molecular weight 1000 in hydroxyl value) obtained by ring-opening polymerization of propylene oxide with glycerol • PPG(1): Polypropylene glycol; "EXCENOL (registered trademark) 1020", manufactured by AGC Corporation, hydroxyl value 112.2 mgKOH / g, molecular weight 1000 in hydroxyl value • AOI: 2-Acryloyloxyethyl isocyanate; "Karenz (registered trademark) AOI", manufactured by Showa Denko Co., Ltd. • Isophorone diisocyanate: "Desmodur (registered trademark) I", manufactured by Sumika Covestro Urethane Co., Ltd. • 2-Hydroxyethyl acrylate; manufactured by Tokyo Chemical Industry Co., Ltd. • 2,5-Di-tri-butanoquinone; manufactured by Tokyo Chemical Industry Co., Ltd., antioxidant • Polyol (8): Polyoxyalkylene triol; "EXCENOL (registered trademark) 3030", manufactured by AGC Co., Ltd., hydroxyl value 56.1 mgKOH / g, molecular weight converted to hydroxyl value 3000 • Photopolymerization initiator: Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide; "Irgacure (registered trademark) 819", manufactured by BASF Co., Ltd. [Determination Methods] The determination methods for various physical properties in the following synthesis and manufacturing examples are as follows. (Hydroxy value) The hydroxyl value was determined according to Method B (automatic potentiometric titration) of JIS K1557-1:2007. (Molecular weight converted to hydroxyl value) The molecular weight converted to hydroxyl value is calculated from the hydroxyl value (unit: mgKOH / g) determined above using the following formula (the molecular weight of potassium hydroxide is 56.1). (Molecular weight converted to hydroxyl value) = 56.1 × 1000 × (number of hydroxyl groups in 1 molecule) / (hydroxyl value) In addition, the number of hydroxyl groups in 1 molecule is considered to be the number of hydroxyl groups in 1 molecule of the initiator used to synthesize the polyol. (Number-average molecular weight (Mn) and weight-average molecular weight (Mw)) The Mn and Mw of carbamate acrylates were determined by gel permeation chromatography (GPC) under the following conditions (converted to polystyrene). The molecular weight distribution (Mw / Mn) was calculated from these values. <Determination Conditions> • Instrument used: "HLC-8320GPC", manufactured by Tosoh Corporation • Column used: Two of the following two types of columns connected in parallel: "TSKgel (registered trademark) SuperHM-H", manufactured by Tosoh Corporation, 2; "TSKgel (registered trademark) SuperH2000", manufactured by Tosoh Corporation, 1 • Column temperature: 40°C • Detector: Differential refractive index (RI) detector • Solution: Tetrahydrofuran • Flow rate: 0.8 mL / min • Sample concentration: 0.5% by mass • Sample injection volume: 100 µL • Standard sample: Polystyrene (Isocyanate group content) The isocyanate group (NCO) content was quantified by reverse titration using an indicator titration method in accordance with Method A of JIS K 1603-1:2007. [Synthesis of Polyols] (Synthesis Example 1) 0.8 g of DMC-TBA and 1200 g of initiator A were fed into a pressure-resistant reactor equipped with a stirrer and a nitrogen inlet pipe. Under nitrogen atmosphere, 30800 g of PO was added at a constant rate for 30 hours at 130°C. The internal pressure of the pressure-resistant reactor was confirmed to have stopped decreasing, and polyol (1) (polyoxypropyltetraol: hydroxyl value 7.7 mgKOH / g, molecular weight converted from hydroxyl value 29100) was obtained. (Synthesis Example 2) 0.2 g of DMC-TBA and 880 g of initiator B were fed into a pressure-resistant reactor equipped with a stirrer and a nitrogen inlet pipe. Under nitrogen atmosphere, 6620 g of PO was added at a constant rate for 6.5 hours at 130°C. It was confirmed that the internal pressure of the pressure-resistant reactor stopped decreasing, and polyol (2) (polyoxypropyl hexaol: hydroxyl value 44.2 mgKOH / g, molecular weight converted to hydroxyl value 7600) was obtained. (Synthesis Example 3) In Synthesis Example 2, the amount of PO added was set to 41120g, and the polyol (3) (polyoxypropyl hexaol: hydroxyl value 8.5mgKOH / g, molecular weight converted to hydroxyl value 39600) was obtained in the same manner as in Synthesis Example 2. (Synthesis Example 4) 0.26 g of DMC-TBA and 1000 g of initiator C were fed into a pressure-resistant reactor equipped with a stirrer and a nitrogen inlet pipe. Under nitrogen atmosphere, 9000 g of PO was added at a constant rate for 9 hours at 130°C. It was confirmed that the internal pressure of the pressure-resistant reactor stopped decreasing, and polyol (4) (polyoxypropyltriol: hydroxyl value 17.0 mgKOH / g, molecular weight converted from hydroxyl value 9900) was obtained. (Synthesis Example 5) In Synthesis Example 4, the amount of PO added was set to 4120g, and the polyol ((5) (polyoxypropyltriol: hydroxyl value 33.7mgKOH / g, molecular weight converted to hydroxyl value 5000) was obtained in the same manner as in Synthesis Example 4. (Synthesis Example 6) 0.2 g of DMC-TBA and 400 g of PPG (1) as an initiator were fed into a pressure-resistant reactor equipped with a stirrer and a nitrogen inlet pipe. Under nitrogen atmosphere, 6200 g of PO was added at a constant rate for 7 hours at 130°C. It was confirmed that the internal pressure of the pressure-resistant reactor stopped decreasing, and polyol (6) (polypropylene glycol: hydroxyl value 7.5 mgKOH / g, molecular weight 15000 converted from hydroxyl value) was obtained. (Synthesis Example 7) In Synthesis Example 6, the amount of PO added was set to 4100g, and the polyol (7) (polypropylene glycol: hydroxyl value 11.2mgKOH / g, molecular weight converted to hydroxyl value 10000) was obtained in the same manner as in Synthesis Example 6. [Preparation of Carbamate Acrylates] (Preparation Example 1) 200 g of polyol (1) and 3.9 g of AOI (NCO index 100) were fed into a reaction vessel equipped with a stirrer and a nitrogen inlet tube. The reaction was carried out at 70°C for 3 hours in the presence of 16 mg of bismuth 2-ethylhexanoate (0.008 parts by mass relative to 100 parts by mass of polyol (1)). Then, 60 mg of 2,5-di-tert-butanoquinone (0.03 ppm by mass relative to 100 parts by mass of polyol (1)) was added to obtain carbamate acrylate (1) (Mn 32000, Mw / Mn 1.23). (Manufacturing Examples 2-6) In Manufacturing Example 1, polyols (2)-(6) were used to replace polyol (1), and carbamate acrylates (2)-(6) were obtained in the same manner as in Manufacturing Example 1. (Manufacturing Example 7) 200 g (0.02 mol) of polyol (7) and 8.9 g (0.04 mol) of isophorone diisocyanate were fed into a reaction vessel equipped with a stirrer and a nitrogen inlet tube. The reaction was carried out at 80°C in the presence of 16 mg of bismuth 2-ethylhexanoate (0.008 parts by mass relative to 100 parts by mass of polyol (7)). After confirming that the isocyanate group content reached the theoretical value (0.81% by mass), 4.6 g (0.04 mol) of 2-hydroxyethyl acrylate was added, and the reaction was continued until the NCO content reached 0% by mass. Then, 60 mg (0.03 ppm by mass relative to 100 parts by mass of polyol (7)) of 2,5-di-tert-butanoquinone was added to obtain carbamate acrylate (7). (Manufacturing Example 8) In Manufacturing Example 7, polyol (8) was used instead of polyol (7), and carbamate acrylate (8) was obtained in the same manner as in Manufacturing Example 7 (the blending ratio of polyol (8) / isophorone diisocyanate / 2-hydroxyethyl acrylate was 1 / 3 / 3). [Preparation of Curable Compositions and Cured Products] (Examples 1-8) Curable compositions and cured products were prepared using the carbamate acrylates (1)-(8) obtained in Examples 1-8, respectively, and the following tests were performed and evaluated. The curable composition was prepared by mixing 0.3 parts by mass of photopolymerization initiator into 100 parts by mass of carbamate acrylate. The test and evaluation results are shown in Table 1. Examples 1-4 are examples, and Examples 5-8 are comparative examples. [Evaluation Item] (Viscosity) The viscosity of the urethane acrylate was determined using an E-type viscometer ("RE85U", manufactured by Toki Sangyo Co., Ltd., 25°C). A viscosity of 30 Pa·s or less facilitates the manufacture of curable components and their cured products. Cases with a viscosity of 30 Pa·s or less were rated "A", and cases with a viscosity greater than 30 Pa·s were rated "B". The evaluations are shown in Table 1. (Tensile Strength) The curing agent was applied to the release surface of the PET film after polysiloxane release treatment using a sprayer, to a thickness of approximately 100µm. Next, the film was irradiated under nitrogen atmosphere using a conveyor belt type UV irradiation machine (manufactured by ORC Corporation; mercury-xenon lamp, illuminance 100mW / cm²). 2 Cumulative light intensity 3J / cm 2 The material is hardened to produce a test specimen for tensile testing. Tensile tests are performed on the specimens using a tensile testing machine (TENSILON universal testing machine "RTG-1310", manufactured by A&D Corporation; tensile speed 300 mm / min) according to JIS K 7311:1995, and the tensile breaking strength (tensile strength) is determined. Cases with a tensile strength of 1.0 MPa or higher are rated "A", and cases with a tensile strength less than 1.0 MPa are rated "B", as shown in Table 1. (Storing shear modulus) The hardening component is clamped in a 0.2 mm gap between a soda-lime glass stage and a measuring shaft ("DISPOSABLE PLATE D-PP20 / AL / S07", manufactured by Anton Paar). Under nitrogen atmosphere and at 35°C, the sample is measured using a mercury-xenon lamp ("Spot Cure SP-9", manufactured by USHIO Electric Co., Ltd.; illuminance 100 mW / cm²) located at the bottom of the stage. 2A hardened specimen of the hardening composition was obtained by irradiating the specimen with ultraviolet light for 300 seconds. Furthermore, to prevent stress in the normal direction of the rotation axis during hardening, the position of the rotation axis was adjusted to automatically follow the direction of rotation. The storage shear modulus of the hardened specimen was measured using a rheometer ("Physica MCR301", manufactured by Anton Paar; 1% dynamic shear strain was applied) while irradiating with ultraviolet light. A higher storage shear modulus indicates a stronger and tougher hardened specimen with excellent shape retention. Hardened specimens with a storage shear modulus of 500 kPa or higher were rated "A", and those with a storage shear modulus of less than 500 kPa were rated "B", as shown in Table 1. (Residual Strain) A 2% dynamic shear strain was applied to the same hardened specimen used for determining the stored shear modulus for 30 minutes, and then the strain was removed. The residual strain after 30 minutes of strain removal was measured using a rheometer ("Physica MCR301", manufactured by Anton Paar). The residual strain was defined as the strain before the application of dynamic shear strain as 0% (baseline). The smaller the residual strain, the better the shape recovery and shape retention of the hardened material during bending. Cases with residual strain below 0.1% were evaluated as "A", and cases with residual strain above 0.1% were evaluated as "B", as shown in Table 1. [Table 1] As can be seen from the evaluation results shown in Table 1, the carbamate acrylates of the present invention (Examples 1-4) have low viscosity and good workability during handling. Furthermore, the cured products containing the carbamate acrylates of the present invention (Examples 1-4) have high tensile strength and storage shear modulus, and low residual strain, thus exhibiting excellent toughness, shape recovery during bending, and shape retention. (none)

Claims

1. A carbamate (meth)acrylate, represented by the following formula (1), and having a number average molecular weight (Mn) of 7500 to 60000; R1-[OC(=O)NH-R2]n…(1) In formula (1), R1 is an n-valent residue after removing the hydroxyl group from a polyol having n hydroxyl groups in one molecule, and n is 4 to 10, wherein the polyol is selected from polyether polyol, polyester polyol and polycarbonate polyol; each of the n R2 in one molecule is an independent residue after removing the isocyanate group from a monoisocyanate, wherein the monoisocyanate has one or more (meth)acrylic acid groups in one molecule.

2. The carbamate (meth)acrylate of claim 1 has a weight average molecular weight (Mw) to number average molecular weight (Mn) ratio (Mw / Mn) of 1.0 to 1.

4.

3. The carbamate (meth)acrylate of claim 1 or 2 is the carbamate esterification product of the aforementioned polyol having n hydroxyl groups in one molecule and the aforementioned monoisocyanate; and the aforementioned polyol having n hydroxyl groups has a molecular weight of 7500 or more when converted by hydroxyl value.

4. The carbamate (meth)acrylate of claim 1 or 2, wherein the polyol having n hydroxyl groups in the aforementioned molecule is a polyether polyol.

5. The carbamate (meth) acrylate of claim 1 or 2, wherein the aforementioned polyether polyol has an oxyalkylene group as a structural unit, and of the total oxyalkylene group, oxypropylene accounts for more than 50% by mass of 100% by mass.

6. A method for manufacturing a carbamate (meth)acrylate, comprising obtaining a reaction product by carbamate reaction of 1 mole of a polyol having n hydroxyl groups in 1 molecule with n moles of monoisocyanate; the aforementioned carbamate (meth)acrylate is represented by the following formula (1), and its number average molecular weight (Mn) is 7500~60000: R1-[OC(=O)NH-R2]n…(1) In formula (1), R1 is an n-valent residue after removing hydroxyl groups from a polyol having n hydroxyl groups in 1 molecule, and n is 4~10, the polyol being selected from polyether polyol, polyester polyol and polycarbonate polyol; each of the n R2 in 1 molecule is an independent residue after removing isocyanate groups from monoisocyanate, the monoisocyanate being having one or more (meth)acrylic acid groups in 1 molecule.

7. The method for manufacturing carbamate (meth)acrylate as claimed in claim 6, wherein the polyol having n hydroxyl groups in the aforementioned molecule has a molecular weight of 7500 or more when converted by hydroxyl value.

8. The method for manufacturing carbamate (meth)acrylate as claimed in claim 6 or 7, wherein the polyol having n hydroxyl groups in the aforementioned molecule is a polyether polyol.

9. The method for manufacturing carbamate (meth)acrylate as claimed in claim 6 or 7, wherein the aforementioned polyether polyol has oxyalkylene groups as structural units, and oxypropylene groups account for more than 50% by mass of 100% by mass of total oxyalkylene groups.

10. A curable composition comprising a carbamate (meth)acrylate as claimed in any one of claims 1 to 5.

11. The curing composition of claim 10, wherein the content of carbamate (meth)acrylate in the aforementioned curing composition is 50% by mass or more.

12. The hardening composition of claim 10 or 11 is a coating agent.

13. A hardened material formed by hardening of any one of the hardening components described in claims 10 to 12.

14. An article having a hardened substance, having the hardened substance as claimed in claim 13.