Ultraviolet-sensing member, microcapsule, method for producing microcapsule, dispersion for forming ultraviolet-sensing layer, ultraviolet-sensing kit

Abstract

The first problem addressed by the present invention is to provide a UV radiation sensitive member that exhibits superior storage stability and image permanence. The second problem addressed by the present invention is to provide microcapsules, a microcapsule production method, a liquid dispersion for forming a UV radiation sensitive layer, and a UV radiation sensitive kit.　A UV radiation sensitive member according to the present invention comprises a UV radiation sensitive layer including microcapsules in which a photoactive agent, a color former, and an aromatic solvent have been encapsulated, wherein the aromatic solvent includes an aromatic solvent that contains heteroatoms and an aromatic solvent that does not contain heteroatoms.

Description

[Technical Field]

[0001] The present invention relates to an ultraviolet sensing element, a microcapsule, a method for producing a microcapsule, a dispersion for forming an ultraviolet sensing layer, and an ultraviolet sensing kit. [Background technology]

[0002] Measurement of ultraviolet light intensity is carried out in various fields, such as measuring the amount of ultraviolet light irradiated onto an object during the curing reaction of ultraviolet-curable resins and measuring the amount of ultraviolet light irradiated onto an object during ultraviolet sterilization of food, etc. A UV actinometer is used to measure the amount of UV light. There are various types of ultraviolet actinometers, such as those that use semiconductor electromotive force and those that use photochromism. For example, Patent Document 1 discloses an ultraviolet actinometer that is an ultraviolet sensing sheet having an ultraviolet sensing layer that includes capsules that encapsulate a color former and a photooxidant. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 017701 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have studied the ultraviolet-sensitive sheet described in Patent Document 1 and found that even an unused sheet (i.e., a sheet before use in measuring the amount of ultraviolet light) may develop color if left in a hot environment for a long period of time. In other words, it has become clear that there is room for improvement in the storage stability of the ultraviolet-sensitive sheet. Furthermore, the inventors have found that when the ultraviolet sensing sheet described in Patent Document 1 is left in a humid and hot environment for a long period of time after being used to measure the amount of ultraviolet light, the color density of the colored portion that develops color upon exposure to ultraviolet light (in other words, the color density of the colored image) may become thinner. In other words, they have found that there is room for improvement so that the color density of the colored portion that develops color upon exposure to ultraviolet light is less likely to decrease even after being left for a long period of time (hereinafter also referred to as "excellent image preservation ability").

[0005] Therefore, an object of the present invention is to provide an ultraviolet sensitive element having excellent storage stability and image preservability. Another object of the present invention is to provide a microcapsule, a method for producing the microcapsule, a dispersion liquid for forming an ultraviolet sensing layer, and an ultraviolet sensing kit. [Means for solving the problem]

[0006] As a result of extensive research into solving the above problems, the present inventors have found that the problems can be solved by the following configuration, and have completed the present invention.

[0007] [1] An ultraviolet sensing element having an ultraviolet sensing layer containing microcapsules encapsulating a photoactivator, a color former, and an aromatic solvent, The ultraviolet sensing element, wherein the aromatic solvent includes an aromatic solvent containing a heteroatom and an aromatic solvent not containing a heteroatom. [2] The ultraviolet sensing element according to [1], wherein the photoactivator contains a compound represented by the general formula (6) described below. [3] The ultraviolet sensing element according to [1] or [2], wherein the mass content ratio of the aromatic solvent containing a heteroatom to the aromatic solvent not containing a heteroatom is 35 / 65 to 85 / 15. [4] The ultraviolet sensing element according to any one of [1] to [3], wherein the aromatic solvent contains one or more aromatic solvents having a boiling point of 100° C. or higher. [5] The ultraviolet sensing element according to any one of [1] to [4], wherein the aromatic solvent containing a heteroatom contains an aromatic phosphate. [6] The photoactivator is a photooxidizer, The ultraviolet sensing element according to any one of [1] to [5], wherein the color former is a color former that develops color upon oxidation. [7] The photoactivator is a photoacid generator, The ultraviolet sensing element according to any one of [1] to [5], wherein the color former is a color former that develops color under the action of an acid. [8] The ultraviolet sensing element according to any one of [1] to [7], wherein the capsule wall of the microcapsule contains one or more resins selected from the group consisting of polyurea, polyurethane urea, and polyurethane. [9] A microcapsule encapsulating a photoactivator, a color former, and an aromatic solvent, The microcapsules, wherein the aromatic solvent comprises an aromatic solvent containing a heteroatom and an aromatic solvent not containing a heteroatom.

[10] The microcapsules according to [9], wherein the photoactivator contains a compound represented by the general formula (6) described below.

[11] The microcapsules according to [9] or

[10] , wherein the mass content ratio of the aromatic solvent containing a heteroatom to the aromatic solvent not containing a heteroatom is 35 / 65 to 85 / 15.

[12] The microcapsules according to any one of [9] to

[11] , wherein the aromatic solvent comprises one or more aromatic solvents having a boiling point of 100°C or higher.

[13] The microcapsule according to any one of [9] to

[12] , wherein the aromatic solvent containing a heteroatom contains an aromatic phosphate.

[14] The photoactivator is a photooxidizer, The microcapsules according to any one of [9] to

[13] , wherein the color former is a color former that develops color upon oxidation.

[15] The photoactivator is a photoacid generator, The microcapsules according to any one of [9] to

[13] , wherein the color former is a color former that develops color under the action of an acid.

[16] The microcapsules according to any one of [9] to

[15] , wherein the capsule wall of the microcapsule contains one or more resins selected from the group consisting of polyurea, polyurethane urea, and polyurethane.

[17] A method for producing the microcapsules according to any one of [9] to

[16] , mixing the color former, the photoactivator, the aromatic solvent, and an emulsifier in water to prepare an emulsion; and forming a resin wall around oil droplets containing the color former, the photoactivator, and the aromatic solvent in the emulsion obtained in the above step to encapsulate the oil droplets, thereby forming the microcapsules.

[18] A dispersion for forming an ultraviolet sensitive layer, comprising the microcapsules according to any one of [9] to

[16] .

[19] An ultraviolet sensing kit comprising the ultraviolet sensing element according to any one of [1] to [8]. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an ultraviolet sensitive element having excellent storage stability and image preservability. Furthermore, according to the present invention, it is possible to provide a microcapsule, a method for producing a microcapsule, a dispersion liquid for forming an ultraviolet sensing layer, and an ultraviolet sensing kit. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing an example of an embodiment of an ultraviolet sensing element of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view showing another example of an embodiment of the ultraviolet sensing element of the present invention. [Figure 3] FIG. 2 is a schematic cross-sectional view showing another example of an embodiment of the ultraviolet sensing element of the present invention. [Figure 4] FIG. 2 is a schematic cross-sectional view showing another example of an embodiment of the ultraviolet sensing element of the present invention. [Figure 5] FIG. 2 is a schematic cross-sectional view showing another example of an embodiment of the ultraviolet sensing element of the present invention. [Figure 6] FIG. 2 is a schematic cross-sectional view showing another example of an embodiment of the ultraviolet sensing element of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below. The following description of the constituent elements may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. Furthermore, in the numerical ranges described in stages in this specification, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this specification, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples. In this specification, the term "solid content" refers to components that form a composition layer formed using the composition, and when the composition contains a solvent (organic solvent, water, etc.), it refers to all components excluding the solvent. Furthermore, liquid components that form a composition layer are also considered to be solid content. In this specification, ultraviolet light refers to light in the wavelength range of 10 to 400 nm. In addition, in this specification, (meth)acrylic means "at least one of acrylic and methacrylic." In this specification, the term "boiling point" refers to the boiling point at standard atmospheric pressure.

[0011] [UV-sensing material] The ultraviolet sensing element of the present invention comprises: An ultraviolet sensing element having an ultraviolet sensing layer including microcapsules encapsulating a photoactivator, a color former, and an aromatic solvent, The aromatic solvents include aromatic solvents containing heteroatoms and aromatic solvents not containing heteroatoms.

[0012] The ultraviolet sensitive element of the present invention having such a structure has excellent storage stability and image preservability. Although the details of why this is so are not clear, the present inventors speculate as follows.

[0013] When the ultraviolet sensing layer of the ultraviolet sensing element of the present invention is irradiated with ultraviolet light during measurement of the amount of ultraviolet light, a colored portion (colored image) is formed in the ultraviolet-irradiated area (ultraviolet-irradiated area) at a color density corresponding to the amount of ultraviolet light (for example, integrated illuminance). "Coloring at a color density corresponding to the amount of ultraviolet light" means that the colored image has gradation corresponding to the amount of ultraviolet light.

[0014] The primary color-developing mechanism of the UV-sensitive layer is due to the microcapsules contained therein. When the UV-sensitive layer is irradiated with UV rays, the color former within the microcapsules present in the UV-irradiated region typically develops color. Specifically, for example, if the photoactivator is a compound that absorbs UV rays and becomes activated to generate acid and / or radicals, the photoactivator absorbs UV rays and becomes activated to generate acid and / or radicals, and the color former develops color through reaction with the acid and / or radicals. In this case, the amount of acid and / or radicals generated by the photoactivator varies depending on the amount of UV irradiated. The amount of color former that develops color also varies depending on the amount of UV irradiated. As a result, in the UV-irradiated region of the UV-sensitive layer, the color density varies depending on the amount of UV irradiated, forming a colored portion with a color density that corresponds to the amount of UV irradiated.

[0015] A characteristic feature of the ultraviolet sensing element of the present invention is that the microcapsules in the ultraviolet sensing layer contain a photoactivator, a color former, and an aromatic solvent, and the aromatic solvents each contain an aromatic solvent containing a heteroatom and an aromatic solvent not containing a heteroatom.

[0016] Aromatic solvents containing heteroatoms are relatively more polar due to the presence of heteroatoms, while aromatic solvents without heteroatoms are relatively less polar due to the absence of heteroatoms. The present inventors have recently demonstrated that when microcapsules in a UV-sensing layer contain only aromatic solvents containing heteroatoms, even unused components readily develop color when placed in a hot environment for extended periods (poor storage stability). The inventors speculate that this is due to the relatively highly polar aromatic solvent containing heteroatoms, which renders the color former in the microcapsules too stable (e.g., when the color former is a leuco dye, the leuco reduction product (color-forming dye) is highly likely to be produced). On the other hand, the inventors have also found that when microcapsules in a UV-sensing layer contain only aromatic solvents containing no heteroatoms, the color density of the colored portion developed by UV irradiation fades when the component is left in a humid and hot environment for extended periods after being used to measure UV doses. The inventors speculate that this is due to the relatively low polarity aromatic solvent containing no heteroatoms, which makes it difficult to stabilize the color former (color-forming dye) produced by the color reaction of the color former in the microcapsules in the component after being used to measure UV doses. As a result of intensive research based on the above findings, the inventors have found that when the microcapsules in the ultraviolet sensing layer contain, as aromatic solvents, an aromatic solvent containing a heteroatom and an aromatic solvent not containing a heteroatom, it is possible to achieve an excellent level of both the storage stability of an unused ultraviolet sensing element and the image preservation properties of the ultraviolet sensing element after it has been used to measure ultraviolet light levels.

[0017] In the following description, the term "better effects of the present invention" may refer to the ultraviolet sensitive member having better storage stability, better image storability, and / or better sensitivity.

[0018] Hereinafter, an embodiment of the ultraviolet sensing element of the present invention will be described in detail with reference to the drawings.

[0019] [First embodiment] FIG. 1 is a schematic cross-sectional view of an embodiment of an ultraviolet sensing member. The ultraviolet sensing component 10 includes a support 12 and an ultraviolet sensing layer 14 disposed on one surface of the support 12 and including microcapsules encapsulating a photoactivator, a color former, and an aromatic solvent. When the ultraviolet sensing layer 14 is irradiated with ultraviolet light, a colored portion (not shown) is formed that develops color at a color density corresponding to the amount of ultraviolet light. In Fig. 1 (and Figs. 2 to 6 shown in the latter part), an embodiment in which the ultraviolet sensing element is in a sheet form is shown, but the ultraviolet sensing element is not limited to this embodiment, and various shapes such as a rectangular parallelepiped, a cylindrical block, etc. can be used as the shape of the ultraviolet sensing element. Among these, a sheet-shaped ultraviolet sensing element is preferably used. The sheet-like ultraviolet sensing member may have various shapes, such as a square, a rectangle, a circle, an ellipse, a polygon other than a rectangle, such as a hexagon, or an irregular shape. The sheet-like ultraviolet sensing member may also be elongated.

[0020] As will be described later, the ultraviolet sensitive member 10 only needs to have the ultraviolet sensitive layer 14 and does not necessarily have to have the support 12 . Furthermore, although the ultraviolet sensing element 10 shown in FIG. 1 has a two-layer structure of the support 12 and the ultraviolet sensing layer 14, the ultraviolet sensing element 10 is not limited to this structure, and may include layers other than the support 12 and the ultraviolet sensing layer 14 (for example, a reflective layer, a glossy layer, a filter layer, etc.), as will be described later.

[0021] The lower limit of the thickness of the ultraviolet sensing member 10 is preferably 5 μm or more, and more preferably 25 μm or more, and the upper limit is preferably 1 cm or less, more preferably 2 mm or less, and even more preferably 250 μm or less. Each component of the ultraviolet sensing element will be described in detail below.

[0022] <<Support>> The support is a member for supporting the ultraviolet sensitive layer. However, if the ultraviolet sensitive layer itself can be handled, the ultraviolet sensitive member does not need to have a support.

[0023] Examples of the support include a resin sheet, paper (including synthetic paper), cloth (including woven and nonwoven fabrics), glass, wood, metal, etc. The support is preferably a resin sheet or paper, more preferably a resin sheet or synthetic paper, and even more preferably a resin sheet. Examples of materials for the resin sheet include polyethylene-based resins, polypropylene-based resins, cyclic polyolefin-based resins, polystyrene-based resins, acrylonitrile-styrene copolymers, acrylonitrile-butadiene-styrene copolymers, polyvinyl chloride-based resins, fluorine-based resins, poly(meth)acrylic resins, polycarbonate-based resins, polyester-based resins (polyethylene terephthalate, polyethylene naphthalate, etc.), polyamide-based resins such as various nylons, polyimide-based resins, polyamideimide-based resins, polyarylphthalate-based resins, silicone-based resins, polysulfone-based resins, polyphenylene sulfide-based resins, polyethersulfone-based resins, polyurethane-based resins, acetal-based resins, and cellulose-based resins. Examples of synthetic paper include those made by biaxially stretching polypropylene or polyethylene terephthalate to form numerous microvoids (such as Yupo), those made using synthetic fibers such as polyethylene, polypropylene, polyethylene terephthalate, and polyamide, and those made by laminating these on part of, one side, or both sides of the paper.

[0024] Another preferred embodiment of the resin sheet is a white resin sheet obtained by dispersing a white pigment in a resin. Examples of the resin material in the white resin sheet include the same materials as those for the resin sheet described above. The white resin sheet has ultraviolet reflectivity. Therefore, when the support is a white resin sheet, ultraviolet light irradiated onto the ultraviolet sensing element is reflected by the support, thereby suppressing scattering of the ultraviolet light within the ultraviolet sensing element. As a result, the detection accuracy of the ultraviolet light amount by the ultraviolet sensing element can be further improved.

[0025] As the white pigment, reference can be made to the white pigments described in paragraph 0080 of WO 2016 / 017701, the contents of which are incorporated herein by reference. The white resin sheet is preferably, for example, a white polyester sheet, more preferably a white polyethylene terephthalate sheet. Commercially available white resin sheets include Yupo (manufactured by Yupo Corporation), Lumirror (manufactured by Toray Industries, Inc.), and Crisper (manufactured by Toyobo Co., Ltd.).

[0026] The lower limit of the thickness of the support is preferably 5 μm or more, more preferably 25 μm or more, and even more preferably 50 μm or more, and the upper limit is preferably 1 cm or less, more preferably 2 mm or less, and even more preferably 250 μm or less.

[0027] <<UV sensing layer>> The ultraviolet sensing layer contains microcapsules (hereinafter also referred to as "specific microcapsules") that encapsulate a photoactive agent, a color former, and aromatic solvents that contain a heteroatom and an aromatic solvent that does not contain a heteroatom as aromatic solvents. The various components that may be included in the UV sensitive layer are described in more detail below.

[0028] <Specific microcapsules> The UV-sensitive layer contains specific microcapsules. First, the materials constituting the specific microcapsules will be described in detail below.

[0029] The specific microcapsules usually have a core portion and a capsule wall for encapsulating the core material (the substance to be encapsulated (also referred to as the encapsulated component)) that constitutes the core portion. The specific microcapsules contain a photoactivator, a color former, and an aromatic solvent as core materials (encapsulated components).

[0030] The specific microcapsules are those in which the substance isolation effect of the capsule wall prevents contact between the inside and outside of the capsule at room temperature. Specific examples include those disclosed in Japanese Patent Laid-Open Nos. 59-190886 and 60-242094, the contents of which are incorporated herein by reference.

[0031] (Capsule wall) The capsule wall of the specific microcapsule is preferably substantially composed of resin. "Substantially composed of resin" means that the resin content relative to the total mass of the capsule wall is 90% by mass or more, and preferably 100% by mass. In other words, the capsule wall of the specific microcapsule is preferably composed of resin. Examples of the resin include polyurethane, polyurea, polyester, polycarbonate, urea-formaldehyde resin, melamine-formaldehyde resin, polystyrene, styrene-methacrylate copolymer, gelatin, polyvinylpyrrolidone, polyvinyl alcohol, etc. Among these, one or more resins selected from the group consisting of polyurea, polyurethane urea, and polyurethane are preferred, as they have a dense crosslinked structure that makes it difficult for the encapsulated substance to leak, thereby further improving the effects of the present invention.

[0032] Polyurea is a polymer having a plurality of urea bonds, and is preferably a reaction product formed from raw materials containing polyamine and polyisocyanate. Polyurea can also be synthesized using polyisocyanate without using polyamine, taking advantage of the fact that a portion of polyisocyanate reacts with water to form polyamine. Polyurethane urea is a polymer having a urethane bond and a urea bond, and is preferably a reaction product formed from raw materials including a polyol, a polyamine, and a polyisocyanate. Note that when reacting a polyol with a polyisocyanate, a portion of the polyisocyanate may react with water to form a polyamine, resulting in the production of polyurethane urea. Polyurethane is a polymer having a plurality of urethane bonds, and is preferably a reaction product formed from raw materials containing polyol and polyisocyanate.

[0033] Examples of polyisocyanates include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene-1,4-diisocyanate, diphenylmethane-4,4-diisocyanate, 3,3'-dimethoxy-4,4'-biphenyl-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate, 4,4'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, and cyclohexylene-1,4-diisocyanate. Examples of suitable isocyanates include diisocyanates such as 4,4',4'-diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, and dicyclohexylmethane diisocyanate; triisocyanates such as 4,4',4'-triphenylmethane triisocyanate and toluene-2,4,6-triisocyanate; tetraisocyanates such as 4,4'-dimethyldiphenylmethane-2,2',5,5'-tetraisocyanate; and isocyanate prepolymers such as an adduct of hexamethylene diisocyanate and trimethylolpropane, an adduct of 2,4-tolylene diisocyanate and trimethylolpropane, an adduct of xylylene diisocyanate and trimethylolpropane, and an adduct of tolylene diisocyanate and hexanetriol. Commercially available polyisocyanates include Takenate (registered trademark) D-102, D-103, D-103H, D-103M2, P49-75S, D-110N, D-120N, D-140N, D-160N, D-127N, D-170N, D-170HN, D-172N, D-177N, D-204, D-165N, NP1100 (manufactured by Mitsui Chemicals, Inc.), Sumidur N3300, Desmodur (registered trademark) L75, UL57SP, Examples include N3200, N3600, N3900, Z4470BA (manufactured by Sumika Bayer Urethane Co., Ltd.), Coronate (registered trademark) HL, HX, L, HK (manufactured by Nippon Polyurethane Co., Ltd.), P301-75E (manufactured by Asahi Kasei Corporation), Duranate (registered trademark) TPA-100, TKA-100, TSA-100, TSS-100, TLA-100, 24A-100, TSE-100 (manufactured by Asahi Kasei Corporation), and Burnock (registered trademark) D-750 (manufactured by DIC Corporation).

[0034] Examples of polyols include aliphatic and aromatic polyhydric alcohols, hydroxy polyesters, and hydroxy polyalkylene ethers. Specific examples of the polyols include those described in JP-A-60-049991, such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, propylene glycol, 2,3-dihydroxybutane, 1,2-dihydroxybutane, 1,3-dihydroxybutane, 2,2-dimethyl-1,3-propanediol, 2,4-pentanediol, 2,5-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, dihydroxycyclohexane, diethylene glycol, 1,2,6-trihydroxyhexane, and 2-phenylpropylene glycol. ethanol, 1,1,1-trimethylolpropane, hexanetriol, pentaerythritol, pentaerythritol ethylene oxide adduct, glycerin ethylene oxide adduct, glycerin, 1,4-di(2-hydroxyethoxy)benzene, condensation products of aromatic polyhydric alcohols and alkylene oxides such as resorcinol dihydroxyethyl ether, p-xylylene glycol, m-xylylene glycol, α,α'-dihydroxy-p-diisopropylbenzene, 4,4'-dihydroxy-diphenylmethane, 2-(p,p'-dihydroxydiphenylmethyl)benzyl alcohol, ethylene oxide adduct of bisphenol A, and propylene oxide adduct of bisphenol A. The polyol is preferably used in an amount such that the ratio of hydroxyl groups is 0.02 to 2 moles per mole of isocyanate groups.

[0035] Examples of polyamines include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, p-phenylenediamine, m-phenylenediamine, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, 2-hydroxytrimethylenediamine, diethylenetriamine, triethylenetriamine, triethylenetetramine, diethylaminopropylamine, tetraethylenepentamine, and amine adducts of epoxy compounds.

[0036] Polyisocyanates can also react with water to form polymeric materials.

[0037] Polyisocyanates, polyols, and polyamines are described in the specifications of U.S. Patent Nos. 3,281,383, 3,773,695, and 3,793,268, Japanese Patent Publication Nos. 48-040347, 49-024159, JP-A-48-080191, and JP-A-48-084086, the contents of which are also incorporated herein by reference.

[0038] The average particle size of the microcapsules is preferably 0.1 to 100 μm in volume average particle size. The lower limit is more preferably 0.3 μm or more, and even more preferably 0.5 μm or more. The upper limit is more preferably 10 μm or less, and even more preferably 5 μm or less. When the average particle size (volume average particle size) of the microcapsules is 0.1 μm or more, the core material inside the capsules can be more stably protected. On the other hand, when the average particle size (volume average particle size) of the microcapsules is 100 μm or less, the resolution of the color image is further improved. The average particle size (volume average particle size) of the microcapsules can be measured, for example, by a laser analysis / scattering type particle size distribution measuring device LA950 (manufactured by Horiba, Ltd.). Furthermore, when measuring the average particle size of the microcapsules contained in the ultraviolet sensing element, the average particle size (volume average particle size) of the microcapsules can be measured using a scanning electron microscope (SEM). Specifically, the surface of the ultraviolet sensing layer is observed with an SEM at 5000x magnification, and the average particle size of all microcapsules present in the observed field of view is determined by image analysis. If microcapsules cannot be observed on the surface, a cross-sectional section is prepared and measured in the same manner as above. The microcapsules mentioned above are a concept that encompasses both specific microcapsules and microcapsules other than the specific microcapsules.

[0039] (color former) The specific microcapsules contain a color former. Here, the term "color former" refers to a compound that develops color from a substantially colorless state (a colorless or weakly colored state). The color former is preferably a compound that develops color upon reaction with an acid and / or radical generated from a photoactivator, as described below. The color former is preferably a compound that develops color when oxidized or a compound that develops color when acted upon by an acid, and is preferably a leuco dye. The leuco dye is preferably a compound that develops color by being oxidized from a substantially colorless state (hereinafter also referred to as an "oxidative color-forming leuco dye"), or a compound that develops color by the action of an acid from a substantially colorless state (hereinafter also referred to as an "acid-color-forming leuco dye"). Examples of leuco dyes include triarylmethane phthalide compounds, fluoran compounds, phenothiazine compounds, indolylphthalide compounds, azaindolylphthalide compounds, leucoauramine compounds, rhodamine lactam compounds, triarylmethane compounds, diarylmethane compounds, triazene compounds, spiropyran compounds, thiazine compounds, and fluorene compounds. For details of the above compounds, reference can be made to the descriptions in U.S. Pat. No. 3,445,234, Japanese Patent Application Laid-Open No. 5-257272, and paragraphs

[0029] to

[0034] of International Publication No. 2009 / 8248. The color former may be used alone or in combination of two or more kinds.

[0040] Oxidative color-developing leuco dye In one embodiment, the oxidative color-forming leuco dye is preferably a compound having one or two hydrogen atoms, which develops color by removing electrons. Examples of such oxidative color-forming leuco dyes include (a) aminotriarylmethanes, (b) aminoxanthines, (c) aminothioxanthines, (d) amino-9,10-dihydroacridine, (e) aminophenoxazines, (f) aminophenothiazines, (g) aminodihydrophenazines, (h) aminodiphenylmethanes, (i) leucoindamines, (j) aminohydrocinnamic acids (cyanoethanes, leucometines), (k) hydrazines, (l) leucoindigoid dyes, (m) amino-2,3-dihydroanthraquinones, (n) tetrahalo-p,p'-biphenols, (o) 2-(p-hydroxyphenyl)-4,5-diphenylimidazoles, and (p) phenethylanilines, as described in U.S. Patent No. 3,445,234. Of the above (a) to (p), (a) to (i) change color by losing one hydrogen atom, and (j) to (p) change color by losing two hydrogen atoms.

[0041] Of these, aminoarylmethanes are preferred, and aminotriarylmethanes are more preferred. The aminotriarylmethane is preferably a compound represented by the following formula (L) or an acid salt thereof.

[0042] [ka]

[0043] In the formula, Ar 1 is the R in the para position relative to the bond to the methane carbon atom specified in formula (A1). 1 R 2 represents a phenyl group having an N-substituent. 2 is the R in the para position relative to the bond to the methane carbon atom specified in formula (A1). 1 R 2R represents a phenyl group having an N-substituent, or a phenyl group having, at the ortho position relative to the methane carbon atom shown in formula (A2), a substituent selected from the group consisting of an alkyl group (preferably an alkyl group having 1 to 4 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 4 carbon atoms), a fluorine atom, a chlorine atom, and a bromine atom. 1 and R 2 each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a 2-hydroxyethyl group, a 2-cyanoethyl group, or a benzyl group. Ar 3 Ar 1 and Ar 2 or represents the same group as at least one of Ar 1 and Ar 2 represents a group different from Ar 3 Ar 1 and Ar 2 If it represents a group different from Ar 3 represents (B1) a phenyl group optionally substituted with a substituent selected from the group consisting of a lower alkyl group (preferably an alkyl group having 1 to 4 carbon atoms), a lower alkoxy group (preferably an alkoxy group having 1 to 4 carbon atoms), a chlorine atom, a diphenylamino group, a cyano group, a nitro group, a hydroxy group, a fluorine atom, a bromine atom, an alkylthio group, an arylthio group, a thioester group, an alkylsulfonic acid group, an arylsulfonic acid group, a sulfonic acid group, a sulfonamide group, an alkylamide group, and an arylamide group; (B2) a naphthyl group optionally substituted with a substituent selected from the group consisting of an amine group, a di-lower alkylamino group, and an alkylamino group; (B3) a pyridyl group optionally substituted with an alkyl group; (B4) a quinolyl group; or (B5) an indolinylidene group optionally substituted with an alkyl group.

[0044] In the above formula (L), R 1 and R 2 is preferably a hydrogen atom or alkyl having 1 to 4 carbon atoms. In addition, in the above formula (L), Ar 1 , Ar 2 , and Ar 3are both R in the para position relative to the bond to the methane carbon atom specified in formula (A1). 1 R 2 It is preferred that they represent phenyl groups having N-substituents, and among these, it is preferred that they are identical groups.

[0045] Specific examples of oxidative color-developing leuco dyes include tris(4-dimethylaminophenyl)methane, tris(4-diethylaminophenyl)methane, bis(4-diethylaminophenyl)-(4-diethylamino-2-methylphenyl)methane, bis(4-diethylamino-2-methylphenyl)-(4-diethylaminophenyl)methane, bis(1-ethyl-2-methylindol-3-yl)-phenylmethane, 2-N-(3-trifluoromethylphenyl)-N-ethylamino-6-diethylamino-9-(2-methoxycarbonylphenyl)xanthene, and 2-(2-chlorophenyl)amino-6-methylindol-3-yl. 2-dibutylamino-9-(2-methoxycarbonylphenyl)xanthene, 2-dibenzylamino-6-diethylamino-9-(2-methoxycarbonylphenyl)xanthene, benzo[a]-6-N,N-diethylamino-9,2-methoxycarbonylphenyl)xanthene, 2-(2-chlorophenyl)-amino-6-dibutylamino-9-(2-methylphenylcarboxamidophenyl)xanthene, 3,6-dimethoxy-9-(2-methoxycarbonyl)-phenylxanthene, benzoyl leucomethylene blue, and 3,7-bis-diethylaminophenoxazine.

[0046] Acid-coloring leuco dye One embodiment of the acid-coloring leuco dye is preferably a compound that develops color by donating electrons or accepting protons from an acid, etc. Specific examples include compounds that have a partial skeleton such as a lactone, lactam, sultone, spiropyran, ester, or amide, and that undergo ring-opening or cleavage upon contact with an acid or a proton. Examples of leuco dyes that develop color under the action of acid (acid-coloring leuco dyes) include 3,3-bis(2-methyl-1-octyl-3-indolyl)phthalide, 6'-(dibutylamino)-2'-bromo-3'-methylspiro[phthalide-3,9'-xanthene], 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide ... and 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide. 2-(2,6-xylidino)-3-methyl-2-(2,6-diethylamino)-fluoran, 2-(2-chloroanilino)-6-dibutylaminofluoran, 3,3-bis(4-methyl-2-indol-3-yl)phthalide, 3-[2,2-bis(1-ethyl-2-methylindol-3-yl)vinyl]-3-(4-diethylaminophenyl)phthalide, 2-anilino-6-dibutylamino-3-methylfluoran, 6-diethylamino-3-methyl-2-(2,6-xylidino)fluoran, 2-(2-chloroanilino)-6-dibutylaminofluoran, 3,3-bis(4- dimethylaminophenyl)-6-dimethylaminophthalide, 2-anilino-6-diethylamino-3-methylfluoran, 9-[ethyl(3-methylbutyl)amino]spiro[12H-benzo[a]xanthene-12,1'(3'H)isobenzofuran]-3'-one, 2'-methyl-6'-(Np-tolyl-N-ethylamino)spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one, 3',6'-bis(diethylaminophenyl) 2'-anilino-6'-(N-ethyl-N-isopentylamino)-3'-methylspiro[phthalide-3,9'-[9H]xanthene], and 6'-(diethylamino)-1',3'-dimethylfluoran.

[0047] (photoactivator) The specific microcapsules encapsulate a photoactivator. The photoactivator is not particularly limited as long as it is a compound that is activated by light, but is preferably a compound that causes a color former to develop color when activated by light. The photoactivator is preferably a compound that is activated by ultraviolet light, and more preferably one or more of a photooxidizing agent and a photoacid generator. In the specific microcapsules, the content ratio of the photoactivator to the color former (photoactivator / color former (mass ratio)) is preferably 0.1 to 30, and more preferably 0.3 to 20, in terms of better sensitivity. In terms of better effects of the present invention, when the photoactivator is a photooxidizing agent, the content ratio of the photoactivator to the color former is more preferably 0.4 to 3, and when the photoactivator is a photoacid generator, the content ratio of the photoactivator to the color former is more preferably 3 to 20. The content ratio of the photoactivator to the color former can be analyzed by extracting the ultraviolet-sensitive layer with methanol and analyzing it by liquid chromatography using a methanol / water mixture as the eluent.

[0048] Photooxidizers The photo-oxidizing agent is preferably a compound that is activated by ultraviolet light to generate radicals and / or exhibits the action of abstracting hydrogen atoms from the color former, thereby causing the color former to develop color. The photo-oxidizing agent is preferably one or more of a radical generator and an organic halogen compound. Furthermore, a preferred embodiment is one in which a radical generator and an organic halogen compound are used in combination as the photo-acid generator. When a radical generator and an organic halogen compound are used in combination, the content ratio of the radical generator to the organic halogen compound (radical generator / organic halogen compound (mass ratio)) is preferably 0.1 to 10, more preferably 0.5 to 5, in order to obtain better gradation in the color-developing portion.

[0049] Radical generators The radical generator is not particularly limited as long as it is a compound that is activated by ultraviolet light to generate radicals. The radical generator is preferably a hydrogen abstraction type radical generator, which has the effect of abstracting a hydrogen atom from the color former to promote the oxidation of the color former. Examples of radical generators include azide polymers described on page 55 of the Abstracts of the 1968 Spring Research Presentation Meeting of the Society of Photography and Imaging of Japan; azide compounds such as 2-azidobenzoxazole, benzoyl azide, and 2-azidobenzimidazole described in U.S. Pat. No. 3,282,693; 3'-ethyl-1-methoxy-2-pyridothiacyanine perchlorate and 1-methoxy-2-methylpyridinium p-toluenesulfonate described in U.S. Pat. No. 3,615,568; lophine dimer compounds such as 2,4,5-triarylimidazole dimer described in Japanese Patent Publication No. 62-039728; benzophenone; p-aminophenyl ketone; polynuclear quinone; thioxanthenone; and the like. Among these, one or more selected from lophine dimer and benzophenone are preferred, with lophine dimer being particularly preferred. Examples of lophine dimers include hexaarylbiimidazole compounds. Examples of hexaarylbiimidazole compounds include the compounds described in paragraph 0047 of WO 2016 / 017701, the contents of which are incorporated herein by reference. Among these, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole is preferred. As 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, for example, "B-CIM" manufactured by Hodogaya Chemical Co., Ltd. can be used.

[0050] As the lophine dimer, a compound represented by the following general formula (1) is also preferred. General formula (1) [ka]

[0051] In general formula (1), A, B, and D each independently represent a carbocyclic or heteroaryl group that is unsubstituted or substituted with a substituent that does not inhibit dissociation of the dimer into an imidazolyl group or oxidation of the color former. B and D are preferably each independently unsubstituted or have 1 to 3 substituents, and A is preferably unsubstituted or have 1 to 4 substituents. The compounds represented by general formula (1) and their production methods can utilize knowledge known as lophine dimers, etc. For example, see U.S. Pat. No. 3,552,973, column 4, line 22 and column 6, line 3, the contents of which are incorporated herein by reference.

[0052] The radical generator may be used alone or in combination of two or more.

[0053] ··Organohalogen compounds The organic halogen compounds may accelerate the oxidation of the color former. As the organic halogen compound, a compound having three or more halogen atoms in the molecule is preferred in terms of achieving better gradation in the color-developing portion. The upper limit of the number of halogen atoms is preferably nine or less. The organic halogen compound is a compound other than lophine dimer and benzophenone. The organic halogen compounds may be used singly or in combination of two or more. Examples of the organic halogen compound include compounds represented by the following general formulas (2) to (7).

[0054] P 0 -CX3···(2) In the formula, P 0 represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, or an aryl group which may have a substituent. Each X independently represents a halogen atom. P 0 Examples of the halogen atom represented by X include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, with a chlorine atom or a bromine atom being preferred. P 0 Examples of the substituent that the alkyl group and aryl group represented by the formula (I) may have include a hydroxy group, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, an acetyl group, and an alkoxy group having 1 to 6 carbon atoms.

[0055] Examples of the compound represented by general formula (2) include trichloromethane, tribromomethane, carbon tetrachloride, carbon tetrabromide, p-nitrobenzotribromide, bromotrichloromethane, pencitrichloride, hexabromoethane, iodoform, 1,1,1-tribromo-2-methyl-2-propanol, 1,1,2,2-tetrabromoethane, 2,2,2-tribromoethanol, and 1,1,1-trichloro-2-methyl-2-propanol.

[0056] General formula (3) [ka]

[0057] In the formula, R represents a substituent, and x represents an integer of 0 to 5.

[0058] Examples of the substituent represented by R include a nitro group, a halogen atom, an alkyl group having 1 to 3 carbon atoms, a haloalkyl group having 1 to 3 carbon atoms, an acetyl group, a haloacetyl group, and an alkoxy group having 1 to 3 carbon atoms. When there are multiple R's in the formula, the R's may be the same or different.

[0059] x is preferably 0 to 3.

[0060] Examples of compounds represented by general formula (3) include o-nitro-α,α,α-tribromoacetophenone, m-nitro-α,α,α-tribromoacetophenone, p-nitro-α,α,α-tribromoacetophenone, α,α,α-tribromoacetophenone, and α,α,α-tribromo-3,4-cycloacetophenone.

[0061] R 1 -SO2-X 1 ...General formula (4)

[0062] In the formula, R 1 represents an alkyl group which may have a substituent, or an aryl group which may have a substituent. 1 represents a halogen atom.

[0063] R 1 The alkyl group represented by the formula (I) is preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, and even more preferably an alkyl group having 1 to 6 carbon atoms. R 1 The aryl group represented by the formula (I) is preferably an aryl group having 6 to 20 carbon atoms, more preferably an aryl group having 6 to 14 carbon atoms, and even more preferably an aryl group having 6 to 10 carbon atoms. R 1 Examples of the substituent that the alkyl group and aryl group represented by the formula (I) may have include a nitro group, a halogen atom, an alkyl group having 1 to 3 carbon atoms, a haloalkyl group having 1 to 3 carbon atoms, an acetyl group, a haloacetyl group, and an alkoxy group having 1 to 3 carbon atoms. X 1 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, with a chlorine atom, a bromine atom, or an iodine atom being preferred, and a chlorine atom or a bromine atom being more preferred.

[0064] Examples of the compound represented by general formula (4) include 2,4-dinitrobenzenesulfonyl chloride, o-nitrobenzenesulfonyl chloride, m-nitrobenzenesulfonyl chloride, 3,3'-diphenylsulfonedisulfonyl chloride, ethanesulfonyl chloride, p-bromobenzenesulfonyl chloride, p-nitrobenzenesulfonyl chloride, p-3-benzenesulfonyl chloride, p-acetamidobenzenesulfonyl chloride, p-chlorobenzenesulfonyl chloride, p-toluenesulfonyl chloride, methanesulfonyl chloride, and benzenesulfonyl bromide.

[0065] R 2 -SX 2 ...General formula (5)

[0066] In the formula, R 2 represents an alkyl group which may have a substituent, or an aryl group which may have a substituent. 2 represents a halogen atom.

[0067] R 2 The alkyl group and the aryl group which may have a substituent, which are represented by the general formula (4), are 1 The preferred embodiments are also the same as those described above. X 2 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, with a chlorine atom, a bromine atom, or an iodine atom being preferred, and a chlorine atom or a bromine atom being more preferred.

[0068] Examples of the compound represented by general formula (5) include 2,4-dinitrobenzenesulfenyl chloride and o-nitrobenzenesulfenyl chloride.

[0069] R 3 -L 1 -CX 3 X 4 X 5 ···(6)

[0070] In the formula, R 3 represents an aryl group which may have a substituent or a heteroaryl group which may have a substituent. 1 represents -SO- or SO2-. 3 , X 4 , and X 5 Each independently represents a hydrogen atom or a halogen atom. 3 , X 4 , and X 5 cannot all be hydrogen atoms.

[0071] R3 The aryl group represented by the formula (I) is preferably an aryl group having 6 to 20 carbon atoms, more preferably an aryl group having 6 to 14 carbon atoms, and even more preferably an aryl group having 6 to 10 carbon atoms. R 3 The heteroaryl group represented by the formula (I) is preferably a heteroaryl group having 4 to 20 carbon atoms, more preferably a heteroaryl group having 4 to 13 carbon atoms, and even more preferably a heteroaryl group having 4 to 9 carbon atoms. R 3 Examples of the substituent that the aryl group and heteroaryl group represented by the formula (I) may have include a nitro group, a halogen atom, an alkyl group having 1 to 3 carbon atoms, a haloalkyl group having 1 to 3 carbon atoms, an acetyl group, a haloacetyl group, and an alkoxy group having 1 to 3 carbon atoms.

[0072] X 3 , X 4 , and X 5 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, with a chlorine atom, a bromine atom, or an iodine atom being preferred, and a chlorine atom or a bromine atom being more preferred.

[0073] Examples of the compound represented by general formula (6) include hexabromodimethyl sulfoxide, pentabromodimethyl sulfoxide, hexabromodimethyl sulfone, trichloromethylphenyl sulfone, tribromomethylphenyl sulfone, trichloro-p-chlorophenyl sulfone, tribromomethyl-p-nitrophenyl sulfone, 2-trichloromethylbenzothiazole sulfone, 4,6-dimethylpyrimidine-2-tribromomethyl sulfone, tetrabromodimethyl sulfone, 2,4-dichlorophenyl-trichloromethyl sulfone, 2-methyl-4-chlorophenyl trichloromethyl sulfone, 2,5-dimethyl-4-chlorophenyl trichloromethyl sulfone, 2,4-dichlorophenyl trimethyl sulfone, and tri-p-tolylsulfonium trifluoromethanesulfonate. Of these, trichloromethylphenyl sulfone or tribromomethylphenyl sulfone is preferred.

[0074] R 4 CX 6 X 7 X 8 ···(7)

[0075] In the formula, R 4 represents a heteroaryl group which may have a substituent. 6 , X 7 , and X 8 Each independently represents a hydrogen atom or a halogen atom. 6 , X 7 , and X 8 cannot all be hydrogen atoms.

[0076] R 4 The heteroaryl group represented by the formula (I) is preferably a heteroaryl group having 4 to 20 carbon atoms, more preferably a heteroaryl group having 4 to 13 carbon atoms, and even more preferably a heteroaryl group having 4 to 9 carbon atoms. R 4 Examples of the substituent that the heteroaryl group represented by the following formula may have include a nitro group, a halogen atom, an alkyl group having 1 to 3 carbon atoms, a haloalkyl group having 1 to 3 carbon atoms, an acetyl group, a haloacetyl group, and an alkoxy group having 1 to 3 carbon atoms. X 6 , X 7 , and X 8 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, with a chlorine atom, a bromine atom, or an iodine atom being preferred, and a chlorine atom or a bromine atom being more preferred.

[0077] Examples of the compound represented by general formula (7) include tribromoquinaldine, 2-tribromomethyl-4-methylquinoline, 4-tribromomethylpyrimidine, 4-phenyl-6-tribromomethylpyrimidine, 2-trichloromethyl-6-nitrobenzothiazole, 1-phenyl-3-trichloromethylpyrazole, 2,5-ditribromomethyl-3,4-dibromothiophene, 2-trichloromethyl-3-(p-butoxystyryl)-1,3,4-oxadiazole, 2,6-dichloromethyl-4-(p-methoxyphenyl)-triazine, and 2-(4-methylphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine.

[0078] Among these, in terms of superior effects of the present invention, the compounds represented by general formula (3), general formula (6), or general formula (7) are preferred, and the compound represented by general formula (6) is more preferred. As the halogen atom, a chlorine atom, a bromine atom, or an iodine atom is preferred, and a chlorine atom or a bromine atom is more preferred.

[0079] Photoacid generator The photoacid generator is preferably a compound that is cleaved by ultraviolet light to generate an acid, and that can cause the color former to develop color by the action of the acid. Examples of the photoacid generator include nonionic photoacid generators and ionic photoacid generators, with nonionic photoacid generators being preferred in terms of superior effects of the present invention. Examples of the nonionic photoacid generator include organic halogen compounds and oxime compounds, with organic halogen compounds being preferred, and the compounds represented by the above-mentioned general formula (6) being more preferred. As the organic halogen compound, a compound having three or more halogen atoms in the molecule is preferred in that the gradation of the color-developing portion is more excellent, and the upper limit of the number of halogen atoms is preferably nine or less. The organic halogen compounds may be used singly or in combination of two or more. Specific examples of the organic halogen compound include the same organic halogen compounds as those listed as the photo-oxidizing agent in the upper part.

[0080] Examples of ionic photoacid generators include diazonium salts, iodonium salts, and sulfonium salts, with iodonium salts and sulfonium salts being preferred. Examples of ionic photoacid color formers include those described in JP-A-62-161860, JP-A-61-067034, and JP-A-62-050382, the contents of which are incorporated herein by reference. The photoacid generator is not particularly limited as long as it is a compound that generates an acid when exposed to light, and may be a photoacid generator that generates an inorganic acid such as a hydrogen halide (e.g., hydrochloric acid), sulfuric acid, or nitric acid, or may be a photoacid generator that generates an organic acid such as a carboxylic acid or a sulfonic acid. In terms of achieving superior effects of the present invention, a photoacid generator that generates an inorganic acid is preferred, and a photoacid generator that generates a hydrogen halide is more preferred.

[0081] Specific examples of photoacid generators include triarylsulfonium hexafluorophosphate, triarylsulfonium arsenate and triarylsulfonium antimonate, diaryliodonium hexafluorophosphate, diaryliodonium arsenate and diaryliodonium antimonate, dialkylphenacylsulfonium tetrafluoroborate and dialkylphenacylsulfonium hexafluorophosphate, dialkyl-4-hydroxyphenylsulfonium tetrafluoroborate and dialkyl-4-hydroxyphenylsulfonium hexafluorophosphate, N-bromosuccinimide, tribromomethylphenyl sulfone, diphenyl iodine, 2-trichloromethyl-5-(p-butoxystyryl)-1,3,4-oxadiazole, and 2,6-ditrichloromethyl-4-(p-methoxyphenyl)-triazine.

[0082] (aromatic solvents) The specific microcapsules contain an aromatic solvent. Furthermore, the specific microcapsules encapsulate, as aromatic solvents, both aromatic solvents containing heteroatoms and aromatic solvents not containing heteroatoms. The aromatic solvent refers to a solvent containing an aromatic ring in the molecule, and the aromatic ring may be a monocyclic ring or a condensed polycyclic ring.

[0083] Examples of the aromatic ring contained in the aromatic solvent include an aromatic hydrocarbon ring and an aromatic heterocyclic ring, and the aromatic hydrocarbon ring is preferred in that it provides superior effects for the present invention. The aromatic hydrocarbon ring may be either a monocyclic ring or a condensed polycyclic ring, but a monocyclic ring is preferred in terms of achieving the effects of the present invention. The aromatic hydrocarbon ring may have a substituent. When the aromatic hydrocarbon ring has a plurality of substituents, the substituents may be bonded to each other to form an alicyclic ring. In other words, the aromatic hydrocarbon ring may contain an alicyclic structure. The number of carbon atoms in the aromatic hydrocarbon ring is not particularly limited, but is preferably 6 to 30, more preferably 6 to 18, and even more preferably 6 to 10. An example of the monocyclic aromatic hydrocarbon ring is a benzene ring. An example of the condensed polycyclic aromatic hydrocarbon ring is a naphthalene ring.

[0084] The aromatic heterocycle may be either a monocycle or a condensed polycycle. The aromatic heterocycle may have a substituent. When the aromatic heterocycle has a plurality of substituents, the substituents may be bonded to each other to form an alicyclic ring. In other words, the aromatic heterocycle may contain an alicyclic structure. Examples of heteroatoms contained in the aromatic heterocycle include a nitrogen atom, an oxygen atom, and a sulfur atom. The number of ring members in the aromatic heterocycle is not particularly limited, but is preferably 5 to 18. Examples of the aromatic heterocycle include a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, a thiophene ring, a thiazole ring, an imidazole ring, and a xanthene ring.

[0085] The number of aromatic rings in the aromatic solvent is not particularly limited and may be 1 or 2 or more. When the aromatic solvent contains 2 or more aromatic rings, the two aromatic rings may form a polycyclic structure (excluding condensed polycyclic structures) by bonding with each other the substituents that may be present on each aromatic ring.

[0086] As described above, the specific microcapsules encapsulate, as aromatic solvents, both aromatic solvents containing heteroatoms and aromatic solvents not containing heteroatoms. In the aromatic solvent containing a heteroatom, the position at which the heteroatom is introduced is not particularly limited. Examples of the aromatic solvent containing a heteroatom include an aromatic solvent containing an aromatic heterocycle in the molecule, and an aromatic solvent containing a heteroatom and an aromatic hydrocarbon ring in the molecule. Examples of the heteroatom in the heteroatom-containing aromatic solvent include atoms other than carbon and hydrogen atoms, and are preferably nitrogen, oxygen, sulfur, or phosphorus atoms. In terms of the effects of the present invention being more excellent, a phosphorus atom is more preferred. Examples of aromatic solvents containing heteroatoms include substituted or unsubstituted benzenesulfonic acid esters such as compounds represented by the general formula (1A) described below, substituted or unsubstituted phthalic acid diesters such as compounds represented by the general formula (1B) described below, and aromatic phosphates such as compounds represented by the general formula (1C) described below. Among these, aromatic phosphates are preferred because they provide better effects of the present invention.

[0087] The aromatic solvent containing no heteroatoms is an aromatic solvent containing no atoms other than carbon atoms and hydrogen atoms. As the aromatic solvent not containing a heteroatom, in terms of the effects of the present invention being more excellent, an aromatic solvent not containing an aromatic hydrocarbon ring with a polycyclic structure is preferred, an aromatic solvent containing one or two monocyclic aromatic hydrocarbon rings is more preferred, and an aromatic solvent containing one or two benzene rings is even more preferred. Examples of aromatic solvents containing no heteroatom include compounds represented by general formula (1D) described below and compounds represented by general formula (1E) described below.

[0088] The specific microcapsules may contain one or more aromatic solvents containing heteroatoms, and may contain one or more aromatic solvents not containing heteroatoms.

[0089] In the specific microcapsules, the mass content ratio of the aromatic solvent containing a heteroatom to the aromatic solvent not containing a heteroatom (aromatic solvent containing a heteroatom / aromatic solvent not containing a heteroatom) is preferably 35 / 65 to 85 / 15, in order to obtain better effects of the present invention.

[0090] In the specific microcapsules, the mass content ratio of the aromatic solvent to the color former (aromatic solvent / color former) is preferably 1 to 100, more preferably 5 to 50, and even more preferably 5 to 25, in order to improve the solubility of the color former and, as a result, to improve the effects of the present invention.

[0091] The mass content ratio of aromatic solvents containing heteroatoms to aromatic solvents not containing heteroatoms in specific microcapsules can be measured by GCMS (gas chromatography mass spectrometry). Specifically, the ultraviolet sensing layer of the ultraviolet sensing element is extracted with acetone, and the resulting extract (filtered if necessary) is concentrated and the resulting sample is analyzed by GCMS to measure the types of aromatic solvents containing heteroatoms and aromatic solvents not containing heteroatoms and their mass content ratios. Furthermore, the mass content ratio of the color former to aromatic solvent in specific microcapsules can be measured by liquid chromatography. Specifically, the ultraviolet sensing layer of the ultraviolet sensing element is extracted with methanol, and the resulting extract is analyzed by liquid chromatography using methanol / water as an eluent.

[0092] As the aromatic solvent containing a heteroatom, for example, compounds represented by the following general formulas (1A) to (1C) are preferred, and as the aromatic solvent not containing a heteroatom, for example, compounds represented by the following general formulas (1D) to (1E) are preferred.

[0093] [ka]

[0094] In general formula (1A), L 11 is an oxysulfonyl group (* 1 -SO2-O-* 2 ), or sulfonyloxy group (* 1 -O-SO2-* 2 ) Note that * 1 represents the bonding position to the phenyl group specified in general formula (1A), and * 2 is R 12 represents the bonding position with R 11 represents a non-aromatic substituent. R 11 The non-aromatic substituent represented by the formula (I) is not particularly limited, but is preferably a monovalent aliphatic hydrocarbon group. R 11 The monovalent aliphatic hydrocarbon group represented by the formula (I) may be either a monovalent saturated aliphatic hydrocarbon group or a monovalent unsaturated aliphatic hydrocarbon group, and may be linear, branched, or cyclic. The number of carbon atoms in the monovalent aliphatic hydrocarbon group is not particularly limited, but is, for example, 1 to 20, preferably 1 to 15, more preferably 1 to 10, still more preferably 1 to 6, particularly preferably 1 to 4, and most preferably 1 to 3. Examples of the monovalent aliphatic hydrocarbon group include alkyl groups, alkenyl groups, and alkynyl groups, with alkyl groups being preferred. The monovalent aliphatic hydrocarbon group may further have a substituent. n 11 represents an integer of 0 to 5. 11 preferably represents an integer of 0 to 2. In addition, n11 If represents an integer of 2 or more, there are multiple R 11 They may be the same or different from each other. R 12 represents a monovalent aliphatic hydrocarbon group. 12 The monovalent aliphatic hydrocarbon group represented by the above-mentioned R 11 The monovalent aliphatic hydrocarbon group may be the same as the monovalent aliphatic hydrocarbon group represented by the following formula:

[0095] Specific examples of the compound represented by general formula (1B) include methyl benzenesulfonate, ethyl benzenesulfonate, methyl toluenesulfonate, and ethyl toluenesulfonate.

[0096] [ka]

[0097] In general formula (1B), R 21 represents a non-aromatic substituent. 21 The non-aromatic substituent represented by R in general formula (1A) 11 The meaning and preferred embodiments are also the same as those of the non-aromatic substituent represented by the following formula: n 21 represents an integer of 0 to 4. 21 preferably represents an integer of 0 to 2. In addition, n 21 If represents an integer of 2 or more, there are multiple R 21 They may be the same or different from each other. R 22 and R 23 R each independently represents a monovalent aliphatic hydrocarbon group. 22 and R 23 The monovalent aliphatic hydrocarbon group represented by the above-mentioned R 11 The monovalent aliphatic hydrocarbon group may be the same as the monovalent aliphatic hydrocarbon group represented by the following formula:

[0098] Specific examples of the compound represented by general formula (1B) include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, and dicyclohexyl phthalate.

[0099] [ka]

[0100] In the above general formula (1C), R 31 ~R 33 each independently represents an alkyl group which may have a substituent, or an aryl group which may have a substituent, provided that R 31 ~R 33 At least one of these represents an aryl group which may have a substituent.

[0101] R 31 ~R 33 The alkyl group represented by the formula (I) may be linear, branched, or cyclic. The alkyl group has, for example, 1 to 20 carbon atoms, preferably 1 to 10, more preferably 1 to 8, and even more preferably 1 to 6.

[0102] R 31 ~R 33 The aryl group represented by the formula (I) is preferably an aryl group having 6 to 20 carbon atoms, more preferably a phenyl group or a naphthyl group, and even more preferably a phenyl group.

[0103] R 31 ~R 33 The alkyl group and aryl group represented by the formula (1A) may have a non-aromatic substituent. 11 The same examples as the non-aromatic substituents represented by the following formula (1) are mentioned, and the preferred embodiments are also the same.

[0104] Specific examples of the compound represented by general formula (1D) include triphenyl phosphate (TPP), tricresyl phosphate (TCP), trixylenyl phosphate (TXP), cresyl diphenyl phosphate (CDP), 2-ethylhexyl diphenyl phosphate (EHDP), t-butylphenyl diphenyl phosphate (t-BDP), bis-(t-butylphenyl)phenyl phosphate (BBDP), tris-(t-butylphenyl)phosphate (TBDP), isopropylphenyl diphenyl phosphate (IPP), bis-(isopropylphenyl)diphenyl phosphate (BIPP), and tris-(isopropylphenyl)phosphate (TIPP).

[0105] [ka]

[0106] In general formula (1D), L 41 represents a single bond or a divalent aliphatic hydrocarbon group. L 41 The divalent aliphatic hydrocarbon group represented by the formula (I) may be either a divalent saturated aliphatic hydrocarbon group or a divalent unsaturated aliphatic hydrocarbon group, and may be linear, branched, or cyclic. The number of carbon atoms in the divalent aliphatic hydrocarbon group is not particularly limited, but is, for example, 1 to 20, preferably 1 to 15, more preferably 1 to 10, even more preferably 1 to 6, particularly preferably 1 to 4, and most preferably 1 or 2. The divalent aliphatic hydrocarbon group includes an alkylene group, an alkenylene group, and an alkynylene group, and is preferably an alkylene group. In addition, the carbon atom of the divalent aliphatic hydrocarbon group may be substituted with a divalent group represented by >C=CH2.

[0107] R 41 and R 42 each independently represents a non-aromatic substituent that does not contain a heteroatom. R 41 and R 42The heteroatom-free non-aromatic substituent represented by the formula (I) is not particularly limited, but is preferably a monovalent aliphatic hydrocarbon group. R 41 and R 42 The monovalent aliphatic hydrocarbon group represented by the formula (I) may be either a monovalent saturated aliphatic hydrocarbon group or a monovalent unsaturated aliphatic hydrocarbon group, and may be linear, branched, or cyclic. The number of carbon atoms in the monovalent aliphatic hydrocarbon group is not particularly limited, but is, for example, 1 to 20. As an example of a suitable embodiment of the number of carbon atoms in the monovalent aliphatic hydrocarbon group, 1 to 15 is preferred, 1 to 10 is more preferred, 1 to 6 is even more preferred, 1 to 4 is particularly preferred, and 1 to 3 is most preferred. Examples of the monovalent aliphatic hydrocarbon group include alkyl groups, alkenyl groups, and alkynyl groups, with alkyl groups being preferred.

[0108] n 41 and n 42 Each of n independently represents an integer of 0 to 5. 41 and n 42 Preferably, n represents an integer of 0 to 2. 41 and n 42 It is preferred that one of these represents 1 or 2 and the other represents 0 or 1. In addition, n 41 and n 42 If represents an integer of 2 or more, there are multiple R 41 R 42 They may be the same or different from each other.

[0109] Specific examples of the compound represented by general formula (1A) include phenylxylylethane, isopropylbiphenyl (e.g., 4-isopropylbiphenyl), diisopropylbiphenyl (e.g., 4,4'-isopropylbiphenyl), α-methylstyrene dimer, 1,2-dimethyl-4-(1-phenylethyl)benzene, 1,3-dimethyl-4-(1-phenylethyl)benzene, 1,4-dimethyl-2-(1-phenylethyl)benzene, and 1-(ethylphenyl)-1-phenylethane.

[0110] [ka]

[0111] In general formula (1E), L 51 represents a single bond. R 51 represents a non-aromatic substituent that does not contain a heteroatom. 51 The non-aromatic substituent not containing a heteroatom represented by R 41 The meaning and preferred embodiments are also the same as those of the non-aromatic substituent not containing a hetero atom represented by the following formula: n 51 represents an integer of 0 to 5. 51 preferably represents an integer of 0 to 2. In addition, n 51 If represents an integer of 2 or more, there are multiple R 51 They may be the same or different from each other. R 52 represents a monovalent aliphatic hydrocarbon group. 52 The monovalent aliphatic hydrocarbon group represented by the formula (1A) is R 12 The monovalent aliphatic hydrocarbon group represented by R 52 The number of carbon atoms in the monovalent aliphatic hydrocarbon group represented by R is preferably 5 to 20. 52 The monovalent aliphatic hydrocarbon group represented by the formula (I) is preferably linear or branched.

[0112] Examples of the compound represented by general formula (1E) include linear or branched alkylbenzenes having 5 to 20 carbon atoms.

[0113] The molecular weight of the aromatic solvent is not particularly limited, and is often 100 or more, and is preferably 150 or more. There is no particular upper limit, but it is preferably 1000 or less, more preferably 600 or less, and even more preferably 500 or less.

[0114] The aromatic solvent preferably contains one or more aromatic solvents having a boiling point of 100° C. or higher. In order to obtain better effects of the present invention, it is more preferable that all aromatic solvents contained in the specific microcapsules have a boiling point of 100° C. or higher. When the boiling point is 100° C. or higher, the aromatic solvent is likely to remain in the capsules without being removed when the microcapsules are subjected to a heating step such as a reaction. The boiling point of the aromatic solvent is more preferably 120° C. or higher, even more preferably 150° C. or higher, and particularly preferably 200° C. or higher, in terms of achieving better effects of the present invention. The upper limit of the boiling point is not particularly limited, but is, for example, 400° C. or lower.

[0115] (Other ingredients) In addition to the above-mentioned components, the specific microcapsules may optionally contain one or more additives such as a solvent other than an aromatic solvent, a reducing agent, a light stabilizer, a wax, an ultraviolet absorber, and an odor suppressant. Among these, it is preferable that the specific microcapsules contain a solvent other than an aromatic solvent and a light stabilizer.

[0116] Solvents other than aromatic solvents The specific microcapsules may contain a solvent other than an aromatic solvent. The content of the aromatic solvent in the specific microcapsules is preferably 50 to 100% by mass, more preferably 75 to 100% by mass, even more preferably 85 to 100% by mass, and particularly preferably 90 to 100% by mass, relative to the total mass of the solvent.

[0117] Light stabilizers The light stabilizer is not particularly limited as long as it is a material that can be stabilized by light, but it is preferable that it acts as a so-called free radical scavenger that traps the free radicals of the activated photoactivator. The light stabilizer may be used alone or in combination of two or more. Examples of light stabilizers include polyhydric phenols such as 2,5-bis(1,1,3,3-tetramethylbutyl)hydroquinone, hydroquinone, catechol, resorcinol, and hydroxyhydroquinone, and aminophenols such as o-aminophenol and p-aminophenol. The content ratio of the light stabilizer to the light active agent (light stabilizer / light active agent (molar ratio)) is preferably 0.0001 to 100, and more preferably 0.0005 to 10.

[0118] Reducing agent The reducing agent has the function of deactivating the photooxidizing agent. When the specific microcapsules contain a reducing agent, it is possible to suppress a rapid change in the color density of the ultraviolet-sensing layer due to ultraviolet irradiation, and it becomes easier to change the color density according to the amount of ultraviolet irradiation. The reducing agent may also function as an antioxidant. The reducing agent may be used alone or in combination of two or more kinds. The reducing agent may be a cyclic phenylhydrazide compound, specifically 1-phenylpyrazolidin-3-one, 1-phenyl-4-methylpyrazolidin-3-one, 1-phenyl-4,4-dimethylpyrazolidin-3-one, 3-methyl-1-p-sulfophenyl-2-pyrazolin-5-one, 3-methyl-1-phenyl-2-pyrazolin-5-one, and 4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidinone (Dimeson S, manufactured by Daito Chemical Co., Ltd.). As the reducing agent, the reducing agents described in paragraphs 0072 to 0075 of WO 2016 / 017701 can be referred to, the contents of which are incorporated herein by reference.

[0119] (Method of manufacturing specific microcapsules) The method for producing the specific microcapsules is not particularly limited, and examples thereof include known methods such as interfacial polymerization, internal polymerization, phase separation, external polymerization, and coacervation.

[0120] An example of a method for producing the specific microcapsules is a method including an emulsification step and an encapsulation step, as shown below. In the encapsulation step, it is preferable to form a resin wall (capsule wall) by interfacial polymerization. Emulsification step: A step of mixing a color former, a photoactivator, an aromatic solvent, and an emulsifier in water to prepare an emulsion. Encapsulation step: A step of encapsulating the oil droplets containing the color former, photoactivator, and aromatic solvent in the emulsion obtained in the above step by forming a resin wall (capsule wall).

[0121] Hereinafter, the interfacial polymerization method will be described as an example of a method for producing specific microcapsules whose capsule walls are polyurea or polyurethane urea. A preferred interfacial polymerization method includes the steps of: dispersing an oil phase containing a photoactivator selected from a photooxidizing agent and a photoacid generator, an aromatic solvent, a solvent containing an aliphatic structure with a boiling point of less than 100°C, a color former, and a capsule wall material (e.g., polyisocyanate) in an aqueous phase containing an emulsifier to prepare an emulsion (emulsification step); and polymerizing the capsule wall material at the interface between the oil phase and the aqueous phase to form a capsule wall and form microcapsules encapsulating the photoactivator selected from a photooxidizing agent and a photoacid generator, the aromatic solvent, and the color former (encapsulation step).

[0122] In the emulsification step, a solvent containing an aliphatic structure and having a boiling point of less than 100° C. is usually added to improve the solubility of the core material in the solvent. The solvent containing an aliphatic structure does not contain an aromatic ring in the molecule. The solvent containing an aliphatic structure is not particularly limited, and examples thereof include ethyl acetate, isopropyl acetate, methyl ethyl ketone, and methylene chloride. The solvent containing an aliphatic structure may be used alone or in combination of two or more.

[0123] The type of emulsifier used in the emulsification step is not particularly limited, and examples thereof include dispersants and surfactants. Examples of dispersants include protective colloids such as water-soluble polymers selected from known anionic polymers, nonionic polymers, and amphoteric polymers. Specific examples include polyvinyl alcohol, gelatin, and cellulose derivatives, with polyvinyl alcohol being preferred. The surfactant is preferably an anionic or nonionic surfactant, and examples thereof include alkylbenzenesulfonates (e.g., sodium dodecylbenzenesulfonate and ammonium dodecylbenzenesulfonate), alkylsulfonates (e.g., sodium lauryl sulfate and sodium dodecylbenzenesulfonate), dioctyl sulfosuccinate sodium salt, and polyalkylene glycols (e.g., polyoxyethylene nonylphenyl ether).

[0124] Other methods for producing specific microcapsules may also be considered, including those described in U.S. Patent Nos. 3,726,804 and 3,796,696, the contents of which are incorporated herein by reference.

[0125] The content of the specific microcapsules in the ultraviolet sensitive layer is not particularly limited, but is preferably 50 to 99% by mass, more preferably 70 to 90% by mass, based on the total mass of the ultraviolet sensitive layer.

[0126] The ultraviolet sensitive layer may contain other components in addition to the specific microcapsules described above. Examples of other components include a polymer binder, a reducing agent, a crosslinking agent, a sensitizer, an ultraviolet absorber, and a surfactant.

[0127] Examples of polymer binders include various emulsions of polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, gum arabic, gelatin, polyvinylpyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylic acid ester, and ethisin-vinyl acetate copolymer. Further, as the polymer binder, the polymer binder described in paragraph 0078 of JP 2017-167155 A can be referred to, the contents of which are incorporated herein by reference. The polymeric binder may be cross-linked, in other words, the polymeric binder may be a cross-linked binder.

[0128] The crosslinking agent is not particularly limited, and for example, glyoxazole can be used. The crosslinking agents described in paragraph 0079 of JP 2017-167155 A can also be used. The contents of these crosslinking agents are incorporated herein by reference.

[0129] For reducing agents, sensitizers, surfactants, and the like, please refer to the descriptions in the lower left column of page 9 to the upper left column of page 10 of JP-A-1-207741 and paragraphs 0038 to 0039 and 0048 to 0059 of JP-A-2004-233614, the contents of which are incorporated herein by reference. Furthermore, the reducing agent, light stabilizer, ultraviolet absorber, and surfactant may be those that can be contained in specific microcapsules.

[0130] The mass per unit area of ​​the ultraviolet sensitive layer (solid content coating amount) is not particularly limited, but is, for example, 3 to 30 g / m 2 is preferred, and 5 to 25 g / m 2 More preferably, 5 to 20 g / m 2 is more preferred.

[0131] The thickness of the ultraviolet sensitive layer is preferably 0.1 to 30 μm, more preferably 1 to 25 μm.

[0132] <Method for forming the ultraviolet sensing layer> The method for forming the ultraviolet sensitive layer is not particularly limited, and known methods can be used. For example, a method may be mentioned in which a dispersion liquid for forming an ultraviolet sensitive layer containing the specific microcapsules is applied onto a support, and the coating film is subjected to a drying treatment as required. The dispersion for forming the ultraviolet sensitive layer preferably contains at least the specific microcapsules. The microcapsule dispersion obtained by the above-mentioned interfacial polymerization method may be used as the dispersion for forming the ultraviolet sensitive layer. The dispersion for forming the ultraviolet sensitive layer may contain other components that may be contained in the ultraviolet sensitive layer described above.

[0133] The method for applying the dispersion liquid for forming an ultraviolet sensitive layer is not particularly limited, and examples of coating machines used for application include an air knife coater, a rod coater, a bar coater, a curtain coater, a gravure coater, an extrusion coater, a die coater, a slide bead coater, and a blade coater.

[0134] After the dispersion for forming the ultraviolet sensitive layer is applied to the support, the coating film may be subjected to a drying treatment, such as a heating treatment, if necessary.

[0135] Although the above describes a method for forming an ultraviolet sensing layer on a support, the present invention is not limited to the above embodiment. For example, after forming an ultraviolet sensing layer on a temporary support, the temporary support may be peeled off to form an ultraviolet sensing member consisting of the ultraviolet sensing layer. The temporary support is not particularly limited as long as it is a releasable support.

[0136] <<Other Layers>> The ultraviolet sensing element may have layers other than the support and the ultraviolet sensing layer described above, such as a reflective layer, a gloss layer, a sensitivity adjusting layer, and a filter layer.

[0137] <Reflective layer> The ultraviolet sensitive element may further comprise a reflective layer. When the ultraviolet sensing element is provided with a reflective layer, the ultraviolet light irradiated onto the ultraviolet sensing element can be reflected by the layer having ultraviolet reflectivity, thereby suppressing scattering of the ultraviolet light within the ultraviolet sensing element and further improving the accuracy of detecting the amount of ultraviolet light. The reflectance of the reflective layer for light with a wavelength of 300 to 380 nm is preferably 10% or more, more preferably 50% or more. The reflectance can be measured by diffuse reflectance measurement using, for example, a UV-visible spectrophotometer (UV-2700 / Shimadzu Corporation). When the support is disposed adjacent to the reflective layer, an adhesive layer may be provided between the support and the reflective layer. The reflective layer and adhesive layer and their manufacturing methods may be referred to in paragraphs 0082 to 0091 of WO 2016 / 017701, the contents of which are incorporated herein by reference.

[0138] <Glossy layer> The ultraviolet sensitive member may further comprise a glossy layer. When the ultraviolet sensing member has a glossy layer, the visibility of the front and back can be improved. The gloss layer and its manufacturing method may be referred to in paragraphs 0092 to 0094 of WO 2016 / 017701, the contents of which are incorporated herein by reference.

[0139] <Filter layer> The ultraviolet sensitive member may further include a filter layer. The filter layer is a layer that selectively transmits light of a specific wavelength. Here, "selectively transmitting light of a specific wavelength" means that light of a specific wavelength is transmitted and other light is blocked. The transmittance of light of the wavelength to be transmitted is, for example, preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. The transmittance of light of the wavelength to be blocked is, for example, preferably 30% or less, more preferably 20% or less, and even more preferably 10% or less.

[0140] The filter layer and its manufacturing method may be referred to in paragraphs 0016 to 0026 of WO 2016 / 017701, the contents of which are incorporated herein by reference.

[0141] <Sensitivity adjustment layer> When the ultraviolet sensitive element includes a filter layer, it may further include a sensitivity adjusting layer on the surface of the filter layer. When the ultraviolet sensitive element includes a sensitivity adjusting layer, the amount of ultraviolet radiation that contributes to color development can be adjusted, enabling color development according to the amount of ultraviolet radiation. The sensitivity adjusting layer may be any layer that affects the amount of ultraviolet light irradiation that contributes to color development, and examples thereof include a layer containing a resin and pigment fine particles, and a film used in a surface protection film, a laminate film, etc.

[0142] The sensitivity adjustment layer and its manufacturing method may be referred to in paragraphs 0095 to 0109 of WO 2016 / 017701, the contents of which are incorporated herein by reference.

[0143] Other Embodiments Other examples of other embodiments of the ultraviolet sensing element are shown below. Note that the layers described in the first embodiment can be applied to the support, ultraviolet sensing layer, reflective layer, adhesive layer, sensitivity adjusting layer, and filter layer constituting the other embodiments shown below.

[0144] Second Embodiment FIG. 2 is a schematic cross-sectional view showing another embodiment of the ultraviolet sensing member. The ultraviolet sensing component 20 includes a support 12, an ultraviolet sensing layer 14 disposed on one surface of the support 12 and containing microcapsules encapsulating a photoactivator, a color former, and an aromatic solvent, and a filter layer 22 disposed on the surface of the ultraviolet sensing layer 14. The support 12 also includes a reflective layer 24 on the surface opposite to the ultraviolet sensing layer 14. The reflective layer 24 may be formed directly on the surface of the support 12, or may be disposed via an adhesive layer (not shown) or the like.

[0145] Third Embodiment FIG. 3 is a schematic cross-sectional view showing another embodiment of the ultraviolet sensing member. The ultraviolet sensing member 30 includes a support 12, an ultraviolet sensing layer 14 disposed on one surface of the support 12 and containing microcapsules encapsulating a photoactivator, a color former, and an aromatic solvent, and a filter layer 22 disposed on the surface of the ultraviolet sensing layer 14. A reflective layer 24 is also provided on the surface of the support 12 opposite the ultraviolet sensing layer 14, and a gloss layer 26 is provided on the surface of the reflective layer 24. The reflective layer 24 may be formed directly on the surface of the support 12, or may be disposed via an adhesive layer (not shown) or the like.

[0146] <Fourth embodiment> FIG. 4 is a schematic cross-sectional view showing another embodiment of the ultraviolet sensing member. The ultraviolet sensing member 40 includes a support 12, a reflective layer 24 disposed on one surface of the support 12, an ultraviolet sensing layer 14 disposed on the surface of the reflective layer 24 and including microcapsules encapsulating a photoactivator, a color former, and an aromatic solvent, and a filter layer 22 disposed on the surface of the ultraviolet sensing layer 14. The reflective layer 24 may be formed directly on the surface of the support 12, or may be disposed via an adhesive layer (not shown) or the like.

[0147] Fifth Embodiment FIG. 5 is a schematic cross-sectional view showing another embodiment of the ultraviolet sensing member. The ultraviolet sensing member 50 includes a support 12, a reflective layer 24 disposed on one surface of the support 12, an ultraviolet sensing layer 14 disposed on the surface of the reflective layer 24 and including microcapsules encapsulating a photoactivator, a color former, and an aromatic solvent, and a filter layer 22 disposed on the surface of the ultraviolet sensing layer 14. The support 12 also includes a gloss layer 26 on the surface opposite to the reflective layer 24. The reflective layer 24 may be formed directly on the surface of the support 12, or may be disposed via an adhesive layer (not shown) or the like.

[0148] Sixth Embodiment FIG. 6 is a schematic cross-sectional view showing another embodiment of the ultraviolet sensing member. The ultraviolet sensing element 60 comprises a support 12, an ultraviolet sensing layer 14 disposed on one surface of the support 12 and containing microcapsules encapsulating a photoactivator, a color former, and an aromatic solvent, and a filter layer 22 disposed on the surface of the ultraviolet sensing layer 14.

[0149] <Other embodiments> In the second to sixth embodiments, the ultraviolet sensing members are provided with the filter layer 22, but the filter layer 22 does not have to be provided. In the second to sixth embodiments, a sensitivity adjustment layer (not shown) may be disposed adjacent to the filter layer 22.

[0150] [Characteristics and uses of ultraviolet-sensing components] The ultraviolet sensing element of the present invention can develop a color according to the amount of ultraviolet light, and the difference in color density of the colored portion can be visually confirmed. Furthermore, when it is made into a sheet form, it is possible to measure the amount of ultraviolet light over a wide area.

[0151] In the case of an ultraviolet sensitive element, the slope of a line obtained by plotting the logarithm of the integrated illuminance of light with a wavelength of 365 nm irradiated onto the ultraviolet sensitive element on a graph with the horizontal axis being the logarithm of the integrated illuminance of the ultraviolet sensitive layer on the vertical axis can be adjusted appropriately depending on the desired application. For example, when the slope is gentle (i.e., when the gradation is gentle), it can be applied to a wide energy range, while when the slope is steep (i.e., when the gradation is steep), it is possible to read fine energy differences. In this specification, the term "integrated illuminance" refers to the integrated illuminance measured at a wavelength of 365 nm, and examples thereof include values ​​measured with a 365 nm UV illuminometer. Also, "color density" is the reflection density D = -log 10 It is a numerical value defined by ρ (ρ is reflectance), and can be measured, for example, with a reflection densitometer (X-Rite310, manufactured by X-Rite).

[0152] The difference in color density of the colored portion may be measured by the following method. After irradiating the UV-sensitive element with a predetermined amount of UV light to cause color development, the resulting element is scanned using a scanner (e.g., GT-F740 / GT-X830, manufactured by Epson) or a reading device such as a smartphone, and the resulting image is analyzed for density in the colored area using a UV light distribution analysis system (FUD-7010J, manufactured by Fujifilm). Correction and calibration processes may be performed as necessary.

[0153] The ultraviolet sensor can be used to measure the amount of ultraviolet light emitted from an ultraviolet light irradiation device when manufacturing components by UV curing an ultraviolet curable resin using a roll-to-roll process. It can also be used to measure the amount of ultraviolet light emitted during the daytime on a daily basis, for example, to determine the degree of sunburn caused by ultraviolet light on people or objects.

[0154] [Dispersion for forming ultraviolet sensitive layer and method for producing the same] The present invention also relates to a dispersion liquid for forming an ultraviolet sensitive layer, which can form the ultraviolet sensitive layer of the ultraviolet sensitive member described above, and a method for producing the same. The dispersion for forming an ultraviolet sensitive layer of the present invention is a dispersion for forming an ultraviolet sensitive layer containing microcapsules encapsulating a photoactivator, a color former, and an aromatic solvent, wherein the aromatic solvent contains an aromatic solvent containing a heteroatom and an aromatic solvent not containing a heteroatom. In other words, the dispersion for forming an ultraviolet sensitive layer of the present invention corresponds to a dispersion containing the above-mentioned specific microcapsules. The composition of the dispersion for forming the ultraviolet sensitive layer of the present invention will be described in detail below.

[0155] The dispersion for forming an ultraviolet sensitive layer of the present invention contains specific microcapsules, which are the same as the specific microcapsules contained in the ultraviolet sensitive member, and the preferred embodiments are also the same. The content of the specific microcapsules in the dispersion liquid for forming the ultraviolet sensitive layer is preferably 50 to 99% by mass, more preferably 70 to 90% by mass, based on the total solid content in the composition.

[0156] The dispersion for forming an ultraviolet sensitive layer of the present invention may contain other components in addition to the specific microcapsules that can be contained in the ultraviolet sensitive layer. Examples of the other components include a polymer binder, a crosslinking agent (a crosslinking agent for forming a crosslinked polymer binder (e.g., glyoxazole, etc.)), a reducing agent, a sensitizer, and a surfactant. Specific examples of the other components are as described above. When the dispersion liquid for forming the ultraviolet sensitive layer contains a polymer binder, the content of the polymer binder is preferably 1 to 50 mass % relative to the total solid content in the composition, more preferably 5 to 40 mass %, and even more preferably 10 to 30 mass %. When the dispersion liquid for forming an ultraviolet sensitive layer contains a surfactant, the content of the surfactant is preferably 0.01 to 10 mass %, more preferably 0.1 to 5 mass %, and even more preferably 0.2 to 1 mass %, relative to the total solid content in the composition.

[0157] The method for producing the dispersion for forming the ultraviolet sensing layer is not particularly limited, and examples thereof include a method including the above-mentioned method for producing the specific microcapsules. That is, examples include a production method including the above-mentioned emulsification step and encapsulation step. Note that the dispersion for forming the ultraviolet sensing layer is preferably a composition obtained by further adding optional components for forming the ultraviolet sensing layer to the microcapsule dispersion obtained by the above-mentioned production method including the emulsification step and encapsulation step.

[0158] [UV Sensor Kit] The present invention also relates to an ultraviolet sensing kit including the ultraviolet sensing element described above. The ultraviolet sensing kit includes at least the ultraviolet sensing member described above. The specific configuration of the ultraviolet detection kit is not particularly limited, and examples include an embodiment that includes an ultraviolet detection element, a element having a filter layer that selectively transmits light of a specific wavelength (preferably a filter sheet that blocks light with a wavelength of 300 nm or more, more preferably a filter sheet that blocks light with a wavelength of more than 230 nm), a light-shielding bag (ultraviolet-blocking bag), a judgment sample, a limit sample (calibration sheet), a focusing tool such as a lens or a concave mirror, and other elements selected from the group consisting of a holding element that holds the ultraviolet detection element. The holding member may have an opening through which ultraviolet light is irradiated onto the held ultraviolet sensing element, or the holding member and the evaluation sample may be integrated. The specific microcapsules may also be kneaded into a resin to form a molded product, such as the resins exemplified as materials for the resin sheet used as the support. [Example]

[0159] The present invention will be described in more detail below based on examples. The materials, amounts used, ratios, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the examples shown below. In the following, "parts" and "%" are by mass unless otherwise specified.

[0160] [Production of UV-sensitive materials] Example 1 Mixture 1 having the following composition was added to 202 parts of a 5% by mass aqueous solution of polyvinyl alcohol, and then emulsified and dispersed at 20°C to obtain an emulsion with a volume average particle size of 1 μm. The resulting emulsion was then stirred at 50°C for 8 hours, after which it was returned to room temperature and filtered to obtain an aqueous capsule dispersion.

[0161] <Composition of Mixture 1> Color former: Leuco Crystal Violet (trade name "LCV", manufactured by Yamada Chemical Co., Ltd.) 2.5 parts Organic halogen compound: Tribromomethylphenyl sulfone (BMPS, manufactured by Sumitomo Seika Chemicals Co., Ltd.) 1.25 parts Aromatic solvent 1: tricresyl phosphate (manufactured by Daihachi Chemical Industry Co., Ltd.) 23 copies Aromatic solvent 2: 7 parts of phenylxylylethane (trade name "Nippon Oil Hisol SAS296", manufactured by JX Nippon Oil & Energy Corporation) Non-aromatic solvent: 50 parts of ethyl acetate (Showa Denko K.K.) Light stabilizer: 2,5-bis(1,1,3,3-tetramethylbutyl)hydroquinone (BTHQ, manufactured by Tokyo Chemical Industry Co., Ltd.) 3 parts Capsule wall material: 31 parts of polyisocyanate (trade name "Takenate D-110N", manufactured by Mitsui Chemicals, Inc., an adduct of xylylene-1,3-diisocyanate and trimethylolpropane, a 75% by mass solution in ethyl acetate)

[0162] 20 parts of the obtained capsule dispersion, 5 parts of a 6 mass % aqueous solution of polyvinyl alcohol (trade name "Denkasize EP-130", manufactured by Denka Co., Ltd.), 0.04 parts of glyoxal (manufactured by Daito Chemical Co., Ltd.), and 0.09 parts of a 50 mass % aqueous solution of sodium dodecylbenzenesulfonate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) were mixed to prepare a dispersion for forming an ultraviolet sensitive layer (coating liquid for forming an ultraviolet sensitive layer).

[0163] The obtained coating liquid for forming the ultraviolet-sensitive layer was applied to a 75 μm-thick white polyethylene terephthalate sheet (product name "Crisper K1212", manufactured by Toyobo Co., Ltd.) in a solid content coating amount of 20 g / m 2 The coating was then dried by heating at 105°C for 1 minute to prepare a sheet-like ultraviolet sensing element having a support and an ultraviolet sensing layer. The ultraviolet sensing layer was about 20 µm thick.

[0164] Example 2 An ultraviolet sensing element was prepared in the same manner as in Example 1, except that mixed solution 1 was changed to mixed solution 2 having the following composition. <Composition of Mixture 2> Color former A: 2.5 parts of 3,3-bis(2-methyl-1-octyl-3-indolyl)phthalide (BASF Ltd.) Organic halogen compound: Tribromomethylphenyl sulfone (BMPS, Sumitomo Seika Chemicals Co., Ltd.) 1.25 parts Aromatic solvent 1: 23 parts of tricresyl phosphate (manufactured by Daihachi Chemical Industry Co., Ltd.) Aromatic solvent 2: 7 parts of phenylxylylethane (trade name "Nippon Oil Hisol SAS296", manufactured by JX Nippon Oil & Energy Corporation) Non-aromatic solvent: 50 parts of ethyl acetate (Showa Denko K.K.) Light stabilizer: 2,5-bis(1,1,3,3-tetramethylbutyl)hydroquinone (BTHQ, manufactured by Tokyo Chemical Industry Co., Ltd.) 3 parts Polyisocyanate: (product name "Takenate D-110N", Mitsui Chemicals, Inc. 31 parts

[0165] Examples 3 to 10 The ultraviolet sensitive members of Examples 3 to 10 were produced in the same manner as in Example 1, except that the components and formulations were changed as shown in Table 1.

[0166] Example 11 An ultraviolet sensing element of Example 11 was produced in the same manner as in Example 2, except that the components and formulation were changed to those shown in Table 1.

[0167] [Comparative Examples 1 and 2] Ultraviolet sensitive elements of Comparative Examples 1 and 2 were prepared in the same manner as in Example 1, except that the components and formulations were changed to those shown in Table 1.

[0168] Table 1 is shown below. The components shown in Table 1 are as follows: Tricresyl phosphate (manufactured by Daihachi Chemical Industry Co., Ltd.) Phenylxylylethane (trade name: Nippon Oil Hisol SAS296, manufactured by JX Nippon Oil & Energy Corporation) Isopropylbiphenyl (Kureha Corporation) α-Methylstyrene dimer (Mitsui Chemicals, Inc.) Dicyclohexyl phthalate (Osaka Organic Chemical Industry Co., Ltd.) BMPS: Tribromomethylphenyl sulfone (Sumitomo Seika Chemicals Co., Ltd.) B-IMD: Rhofein dimer (2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, trade name "B-IMD", manufactured by Kurogane Kasei Co., Ltd.) LCV: Leuco Crystal Violet (product name "LCV", manufactured by Yamada Chemical Co., Ltd.) Color former A: 3,3-bis(2-methyl-1-octyl-3-indolyl)phthalide (BASF) BTHQ: 2,5-bis(1,1,3,3-tetramethylbutyl)hydroquinone (Tokyo Chemical Industry Co., Ltd.)

[0169] In addition, in the "Photoactivator" column in Table 1, the numerical values ​​in parentheses listed together with the component names indicate blended parts (parts by mass). Furthermore, the color formers used in Examples 1, 3 to 10 and Comparative Examples 1 and 2 correspond to color formers that develop color upon oxidation. The color formers used in Examples 1, 3 to 10 and Comparative Examples 1 and 2 develop a blue color upon oxidation. On the other hand, the color formers used in Examples 2 and 11 correspond to color formers that develop a color upon the action of an acid. The color formers used in Examples 2 and 11 develop a red color upon the action of an acid. In addition, the column "mass content ratio of aromatic solvent 1 to aromatic solvent 2" in Table 1 indicates "aromatic solvent 1 / aromatic solvent 2."

[0170] [Table 1]

[0171] [Measurement and Evaluation] The image preservation property, storage stability and sensitivity of the ultraviolet sensitive elements prepared in each of the Examples and Comparative Examples were measured and evaluated by the following methods. The color density of the ultraviolet sensitive element was measured using a reflection densitometer (X-Rite 310, manufactured by X-Rite Corporation). As described above, the color formers used in Examples 1, 3 to 10 and Comparative Examples 1 and 2 exhibit a blue color upon oxidation, while the color formers used in Examples 2 and 11 exhibit a red color upon the action of acid. In measuring the color density of the ultraviolet sensitive element, OD-M values ​​were used for Examples 2 and 11, and OD-C values ​​were used for Examples 1, 3 to 10 and Comparative Examples 1 and 2.

[0172] [Image storage performance] The ultraviolet sensing layer of the ultraviolet sensing element prepared in each example and comparative example was irradiated with ultraviolet light using a high-pressure mercury lamp at an integrated illuminance of 10 mJ / cm 2 Then, the density (DA1) of the colored portion formed in the ultraviolet sensitive layer was measured using a reflection densitometer. Next, the ultraviolet sensing element after ultraviolet irradiation was stored for 1 day in an environment of a temperature of 40°C and a humidity of 90% RH. After storage, the density (DA2) of the colored portion formed in the ultraviolet sensing layer was measured using a reflection densitometer. The density retention rate was calculated using the following formula (1), and the evaluation was carried out according to the following criteria. The results are shown in Table 1. Formula (1): Concentration maintenance rate (%)=Concentration DA2 / Concentration DA1×100

[0173] (Evaluation criteria) "A": Concentration maintenance rate (%) is 95% or more "B": Concentration maintenance rate (%) is 90% or more but less than 95% "C": Concentration maintenance rate (%) is less than 90%

[0174] [Storage stability] The initial density (DA3) of the ultraviolet sensitive layer of the ultraviolet sensitive member (unused) prepared in each of the Examples and Comparative Examples was measured using a reflection densitometer. Next, the ultraviolet sensitive elements (unused) prepared in each of the examples and comparative examples were stored at a temperature of 140° C. for 600 seconds, and then the density (DA4) of the ultraviolet sensitive layer was measured using a reflection densitometer. Then, based on the value (amount of change in density ΔD) obtained by subtracting density DA3 from density DA4, evaluation was carried out according to the following evaluation criteria. The results are shown in Table 1. Note that the smaller the ΔD value, the less color develops during storage and the better the storage stability. <Evaluation criteria> "A": ΔD is 0.2 or less "B": ΔD is greater than 0.2 and less than 0.4 "C": ΔD is more than 0.4

[0175] 〔sensitivity〕 The ultraviolet sensing layer of the ultraviolet sensing element prepared in each example and comparative example was irradiated with ultraviolet light using a high-pressure mercury lamp at an integrated illuminance of 10 mJ / cm 2 The ultraviolet sensitive layer was then irradiated so that the density (DA5) of the colored portion formed in the ultraviolet sensitive layer was measured using a reflection densitometer, and the sensitivity was evaluated based on the following evaluation criteria. The higher the density (DA5) of the colored portion, the higher the sensitivity. The results are shown in Table 1.

[0176] <Evaluation criteria> "A": 0.4 or higher "B": Less than 0.4

[0177] From the results in Table 1, it is clear that the ultraviolet sensitive element of the present invention is excellent in storage stability and image preservability, and further, it is clear that the ultraviolet sensitive element of the present invention is also excellent in sensitivity.

[0178] Furthermore, a comparison between Example 1 and Example 2 confirmed that when the color former is a color former that develops color upon oxidation, the image storage stability is superior. Comparing Examples 1, 3 to 6, it was confirmed that when the mass content ratio (aromatic solvent containing heteroatoms / aromatic solvent not containing heteroatoms) of the aromatic solvent containing heteroatoms (aromatic solvent 1) to the aromatic solvent not containing heteroatoms (aromatic solvent 2) in the microcapsules is 35 / 65 to 85 / 15, the storage stability, image storage stability, and sensitivity are better. [Explanation of symbols]

[0179] 10, 20, 30, 40, 50, 60 UV-sensitive material 12 Support 14 UV sensing layer 22 Filter Layer 24 Reflective layer 26 Glossy layer

Claims

1. An ultraviolet sensing element having an ultraviolet sensing layer including microcapsules encapsulating a photoactivator, a color former, and an aromatic solvent, the aromatic solvents include aromatic solvents containing heteroatoms and aromatic solvents not containing heteroatoms, the aromatic solvent containing a heteroatom is a compound represented by general formula (1C), The ultraviolet sensing element, wherein the aromatic solvent containing no heteroatom is a compound represented by general formula (1D): 【Chemistry 1】 In the formula, R 31 to R 33 each independently represent an alkyl group which may have a non-aromatic substituent, or an aryl group which may have a non-aromatic substituent, provided that at least one of R 31 to R 33 represents an aryl group which may have a non-aromatic substituent. 【Chemistry 2】 In the formula, L 41 represents a single bond or an alkylene group having 1 to 6 carbon atoms in which a carbon atom may be substituted with >C=CH 2 . R 41 and R 42 each independently represent a non-aromatic substituent containing no heteroatom. n 41 and n 42 each independently represent an integer of 0 to 5. When n 41 and n 42 each represent an integer of 2 or greater, the multiple R 41 s and the multiple R 42 s may be the same or different from each other.

2. 2. The ultraviolet sensing element according to claim 1, wherein the mass ratio of the aromatic solvent containing a heteroatom to the aromatic solvent not containing a heteroatom is 35 / 65 to 85 / 15.

3. 3. The ultraviolet sensing element according to claim 1, wherein the aromatic solvent comprises one or more aromatic solvents having a boiling point of 100°C or higher.

4. An ultraviolet sensing element having an ultraviolet sensing layer containing microcapsules encapsulating a photoactivator, a color former, dicyclohexyl phthalate, and phenylxylylethane.

5. 5. The ultraviolet sensing element according to claim 1, wherein the photoactivator comprises a compound represented by the following general formula (6): R 3 -L 1 -CX 3 X 4 X 5 ・・・(6) In the formula, R 3 represents an aryl group which may have a substituent or a heteroaryl group which may have a substituent. 1 is -SO- or -SO ２ - represents X 3 , X 4 , and X 5 each independently represents a hydrogen atom or a halogen atom. 3 , X 4 , and X 5 cannot all be hydrogen atoms.

6. the photoactivator is a photooxidant; 6. The ultraviolet sensing element according to claim 1, wherein the color former is a color former that develops color upon oxidation.

7. the photoactivator is a photoacid generator; 6. The ultraviolet sensing element according to claim 1, wherein the color former is a color former that develops color under the action of an acid.

8. 8. The ultraviolet sensing element according to claim 1, wherein the capsule wall of the microcapsule contains one or more resins selected from the group consisting of polyurea, polyurethane urea, and polyurethane.

9. A microcapsule encapsulating a photoactivator, a color former, and an aromatic solvent, the aromatic solvents include aromatic solvents containing heteroatoms and aromatic solvents not containing heteroatoms, the aromatic solvent containing a heteroatom is a compound represented by general formula (1C), The microcapsules, wherein the aromatic solvent containing no heteroatom is a compound represented by general formula (1D): 【Transformation 3】 In the formula, R 31 to R 33 each independently represent an alkyl group which may have a non-aromatic substituent, or an aryl group which may have a non-aromatic substituent, provided that at least one of R 31 to R 33 represents an aryl group which may have a non-aromatic substituent. 【Chemistry 4】 In the formula, L 41 represents a single bond or an alkylene group having 1 to 6 carbon atoms in which a carbon atom may be substituted with >C=CH 2 . R 41 and R 42 each independently represent a non-aromatic substituent containing no heteroatom. n 41 and n 42 each independently represent an integer of 0 to 5. When n 41 and n 42 each represent an integer of 2 or greater, the multiple R 41 s and the multiple R 42 s may be the same or different from each other.

10. The microcapsule according to claim 9, wherein the mass content ratio of the aromatic solvent containing a heteroatom to the aromatic solvent not containing a heteroatom is 35 / 65 to 85 / 15.

11. The microcapsule according to claim 9 or 10, wherein the aromatic solvent comprises one or more aromatic solvents having a boiling point of 100°C or higher.

12. A microcapsule containing a photoactivator, a color former, dicyclohexyl phthalate, and phenylxylylethane.

13. The microcapsule according to any one of claims 9 to 12, wherein the photoactivator comprises a compound represented by the following general formula (6): R 3 -L 1 -CX 3 X 4 X 5 ・・・(6) In the formula, R 3 represents an aryl group which may have a substituent or a heteroaryl group which may have a substituent. 1 is -SO- or -SO ２ - represents X 3 , X 4 , and X 5 each independently represents a hydrogen atom or a halogen atom. 3 , X 4 , and X 5 cannot all be hydrogen atoms.

14. the photoactivator is a photooxidant; The microcapsule according to any one of claims 9 to 13, wherein the color former is a color former that develops color upon oxidation.

15. the photoactivator is a photoacid generator; The microcapsule according to any one of claims 9 to 13, wherein the color former is a color former that develops color under the action of an acid.

16. The microcapsule according to any one of claims 9 to 15, wherein the capsule wall of the microcapsule contains one or more resins selected from the group consisting of polyurea, polyurethane urea, and polyurethane.

17. A method for producing microcapsules according to any one of claims 9 to 11, mixing the color former, the photoactivator, the aromatic solvent, and an emulsifier in water to prepare an emulsion; and forming a resin wall around oil droplets containing the color former, the photoactivator, and the aromatic solvent in the emulsion obtained in the above step to encapsulate the oil droplets, thereby forming the microcapsules.

18. A dispersion for forming an ultraviolet sensitive layer, comprising the microcapsules according to any one of claims 9 to 16.

19. An ultraviolet sensing kit comprising the ultraviolet sensing element according to any one of claims 1 to 8.

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