JP2014174505A - Ultraviolet-sensing sheet, production method thereof, and method for sensing ultraviolet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultraviolet-sensing sheet with which the amount of ultraviolet irradiation can be easily measured over a large area and which is excellent in terms of the measurement of the amount of ultraviolet in the range of 10 mJ/cmto 10000 mJ/cm, and to provide a production method thereof and a method for sensing ultraviolet.SOLUTION: An ultraviolet-sensing sheet comprises an ultraviolet-sensing layer which comprises capsules including a photooxidant, a leuco dye which can be oxidized by the photooxidant to develop a color and a reductant, and the mass ratio of the photooxidant and the leuco dye is 0.2 to 1.0:1 and the molar ratio of the photooxidant and the reductant is 1:0.01 to 10. The amount of the leuco dye is 0.1 to 1.0 g per mof the surface area of the ultraviolet-sensing layer.

Description

  The present invention relates to an ultraviolet ray sensing sheet, an ultraviolet ray sensing sheet manufacturing method, and an ultraviolet ray sensing method using the ultraviolet ray sensing sheet.

  The measurement of the amount of ultraviolet rays is used in various fields. For example, the amount of ultraviolet rays irradiated to an irradiated object in an ultraviolet irradiation device for curing an ultraviolet curable resin is measured using an ultraviolet light meter. ing.

  As an ultraviolet light meter, a device using a semiconductor photovoltaic power is generally known, but it is expensive and inconvenient to carry. A cheap and simple card-like one using a photochromic material is known, but this is reversibly discolored by ultraviolet rays, and the ultraviolet intensity during irradiation can be known. The accumulated dose cannot be known.

  As a method for measuring the accumulated irradiation dose, for example, Patent Document 1 proposes a method using a color changing material.

  In addition, as a method for measuring the amount of ultraviolet rays, a method of quantifying using photosensitive paper (see Patent Document 2) and a method using oxidation coloring of a leuco dye (see Patent Document 3) have been proposed.

Japanese Patent Laid-Open No. 10-288552 JP-A-10-122958 JP-A-62-112020

Here, the method described in Patent Document 1 has a problem that the sensitivity is insufficient and it is not suitable for quantification. In addition, the techniques described in Patent Documents 2 and 3 are all intended for recording, and are not suitable for measuring a wide range of irradiation doses. Furthermore, ultraviolet irradiation dose in the manufacturing process using a UV curing, for example, in the range of 10~1000mJ / cm ^2, in particular, in the range of 100~1000J / cm ² is, although the most widely used It was not suitable for the measurement of the range suitable for it.
On the other hand, even if it is an ultraviolet-sensitive sheet that solves the above-mentioned problems, if it reacts even with a small amount of ultraviolet irradiation, it may develop color due to the accumulation of a small amount of ultraviolet-ray when stored for a long time, or it may be inconvenient depending on the application. May occur.
The present invention has been made to solve the above-described problems, and is an ultraviolet light sensing sheet that is easy to measure the amount of ultraviolet irradiation over a wide area and excellent in measuring the amount of ultraviolet light. The present invention relates to an undetectable UV detection sheet.
Another object of the present invention is to provide a method for producing such an ultraviolet sensing sheet and an ultraviolet sensing method using the ultraviolet sensing sheet.

Under such circumstances, the present inventor has solved this problem by further blending a small amount of a reducing agent into a capsule containing a photooxidant and a leuco dye. That is, normally, the photo-oxidant in the capsule absorbs ultraviolet rays and develops a leuco dye, but by adding a small amount of reducing agent, even if a small amount of ultraviolet light enters the capsule, Oxidant radicals are suppressed and no color develops. On the other hand, since the amount of the reducing agent is very small, when the UV integrated illuminance increases, radical generation of the photooxidant occurs and color develops. As a result, color development was successful when the UV integrated illuminance reached a certain level (for example, 10 mJ / m ² or more), and the present invention was completed.

Means for solving the above problems are the following means <1>, preferably the following means <2> to <13>.
<1> A capsule containing a photo-oxidant, a leuco dye that can be oxidized and colored by the photo-oxidant, and a reducing agent, wherein the mass ratio of the photo-oxidant and the leuco dye is 0.2 to 1.0: 1. , Having a UV-sensitive layer in which the molar ratio of the photo-oxidant to the reducing agent is 1: 0.01 to 10, and the amount of leuco dye per 1 m ² of the surface area of the UV-sensitive layer is 0.1 to 1.0 g. A certain UV sensitive sheet.
<2> The ultraviolet ray sensitive sheet according to <1>, wherein the reducing agent is a phenol-based antioxidant.
<3> The ultraviolet-sensitive sheet according to <1> or <2>, wherein ε at a wavelength of 350 nm is 2000 or less and ε at a wavelength of 250 nm is 10,000 or more (where ε is a photooxidant) The molar extinction coefficient of
<4> The ultraviolet ray sensitive sheet according to any one of <1> to <3>, wherein the capsule is a microcapsule.
<5> The ultraviolet ray sensitive sheet according to any one of <1> to <4>, wherein the leuco dye is aminoarylmethane.
<6> Any one of <1> to <5>, in which when the ultraviolet-sensitive sheet is irradiated with a high-pressure mercury lamp, the integrated illuminance when measured at a wavelength of 365 nm is in the range of 10 to 10,000 mJ / cm ^2. UV detection sheet.
<7> The ultraviolet ray sensitive sheet according to any one of <1> to <6>, having an ultraviolet ray sensitive layer on a support.
<8> The ultraviolet-sensitive sheet according to <7>, wherein the support is a plastic film.
<9> when irradiated with a high pressure mercury lamp, the integrated intensity reflection density variation in the range of less than 10 mJ / cm ² or more 100mJ / cm ² ΔD1,100mJ / cm ² or more 1000 mJ / cm ² less than in when measured at a wavelength of 365nm reflection density variation in range .DELTA.D2, and 1000 mJ / cm ² or more 10000 mJ / cm reflection density variation in the ^two following ranges ΔD3 is respectively 0.2 or more, <1> or UV-sensing sheet to <8>.
<10> When irradiated with a high-pressure mercury lamp, the reflection density change ΔD0 is less than 0.2 when the integrated illuminance is 1 mJ / cm ² or more and less than 10 mJ / cm ² when measured at a wavelength of 365 nm. <9> The ultraviolet ray detection sheet according to any one of the above.
<11> A capsule containing a photo oxidant, a leuco dye that can be oxidatively colored by the photo oxidant, and a reducing agent on a support, wherein the mass ratio of the photo oxidant to the leuco dye is 0.2 to An ultraviolet-sensitive layer composition in which the molar ratio of photooxidizer to reducing agent is 1: 0.01 to 1.0: 1: 1 and the amount of leuco dye per 1 m ² of the surface area of the support is 0. The manufacturing method of a ultraviolet-sensitive sheet including applying so that it may become 0.1-1.0g.
<12> The method for producing an ultraviolet detection sheet according to <11>, wherein the ultraviolet detection sheet is any one of <1> to <10>.
<13> An ultraviolet ray detection method at an ultraviolet ray integrated illuminance of 10 to 10,000 mJ / m ² , wherein the ultraviolet ray detection sheet according to any one of <1> to <10> is used.

  According to the present invention, it is possible to provide an ultraviolet ray sensing sheet that is easy to measure the amount of ultraviolet ray irradiation over a wide area and is excellent in ultraviolet ray amount measurement. Furthermore, it has become possible to provide a method for producing an ultraviolet sensing sheet and an ultraviolet sensing method using the ultraviolet sensing sheet.

It is a conceptual diagram which shows the grade of the coloring of this invention. It is the schematic of an example of the capsule used by this invention. It is the figure which showed an example of the reaction scheme of a photooxidant and a leuco dye. It is the schematic cross section which showed an example of the ultraviolet rays detection sheet of this invention.

  Hereinafter, the contents of the present invention will be described in detail. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

The ultraviolet-sensitive sheet of the present invention includes a capsule containing a photooxidant, a leuco dye that can be oxidized and colored by the photooxidant, and a reducing agent, and the mass ratio of the photooxidant to the leuco dye is 0.2 to 1. 0: 1, having a UV-sensitive layer in which the molar ratio of photooxidizer to reducing agent is 1: 0.01-10, and the amount of leuco dye per m ² of surface area of the UV-sensitive layer is 0.1 It is -1.0g.

By adopting a configuration that satisfies at least one of the above, it is possible to react with ultraviolet rays with high sensitivity and detect ultraviolet rays. In particular, when the ultraviolet-sensitive sheet of the present invention is irradiated with a high-pressure mercury lamp, the ultraviolet-sensitive sheet of the present invention has a different degree of color depending on the amount of irradiation when measured at a wavelength of 365 nm. Can be detected. The high-pressure mercury lamp here refers to, for example, a high-pressure UV lamp manufactured by USHIO. FIG. 1 is a conceptual diagram showing the degree of color development according to the present invention. The vertical axis corresponds to the logarithm of the degree of color development, and the horizontal axis corresponds to the integrated illuminance of ultraviolet rays. As is apparent from FIG. 1, in the present invention, it is possible to continuously develop color from 10 mJ / cm ² according to the integrated illuminance of ultraviolet rays, and it is possible to sense ultraviolet rays with high sensitivity. In the present invention, in particular, it is possible to effectively detect ultraviolet rays when the integrated illuminance of ultraviolet rays is in the range of 10 to 10,000 mJ / cm ² , and further in the range of 100 to 10,000 mJ / cm ² .
In addition, as a light source of this invention, not only a high pressure mercury lamp but another light source can be used. For example, a metal halide lamp, a UV-LED lamp, a low-pressure mercury lamp, a UV laser, or the like may be used.

UV sensitive sheet of the present invention, the reflection in the range of less than the reflection density change ΔD1,10mJ / cm ² or more 1000 mJ / cm ² cumulative illuminance in the range of less than 10 mJ / cm ² or more 100 mJ / cm ² at the time when measured at a wavelength of 365nm preferably the concentration change .DELTA.D2, and 1000 mJ / cm ² or more 10000 mJ / cm reflection density variation in the ^two following ranges ΔD3 is respectively 0.2 or more, respectively, and more preferably 0.25 or more. Although there is no restriction | limiting in particular about an upper limit, It is preferable that it is 0.4 or less. For example, ΔD1 is 0.21 to 0.36 mJ / cm ² , ΔD2 is 0.22 to 0.29 mJ / cm ² , and ΔD3 is 0.21 to 0.29 mJ / cm ² . The reflection density change ΔD0 in the range of 1 mJ / cm ² or more and less than 10 mJ / cm ² is preferably less than 0.2, more preferably less than 0.1, and less than 0.05. Further preferred. The reflection density change means a color change amount before and after irradiation with ultraviolet rays having a predetermined integrated illuminance. Specifically, the reflection density meter (X-Rite 310, manufactured by X-Rite) is used. Can be measured.
By setting the reflection density changes ΔD0 to ΔD3 within the above range, the color can be continuously developed according to the integrated illuminance of the ultraviolet rays, and the ultraviolet rays can be sensed with high sensitivity.

Such effective UV sensing is achieved by the UV sensing layer. The ultraviolet-sensitive layer in the present invention includes a capsule containing a photo-oxidant, a leuco dye that can be oxidized and colored by the photo-oxidant, and a reducing agent, and the mass ratio of the photo-oxidant to the leuco dye is 0.2 to 1. 0.0: 1, and the molar ratio of photooxidant to reducing agent is 1: 0.01 to 10. The amount of leuco dye per 1 m ² of the surface area of the UV-sensitive layer is 0.1 to 1.0 g. It is characterized by that.

The mechanism of UV detection according to the present invention will be described with reference to FIGS. Needless to say, the present invention is not limited to these drawings.
FIG. 2 is a schematic view of an example of a capsule used in the present invention. As shown in FIG. 2, a photooxidant 12, a leuco dye 13, and a reducing agent 14 are encapsulated in the capsule 11. FIG. 3 is a diagram showing an example of a reaction scheme between a photooxidant and a leuco dye.
As shown in FIG. 2, when the ultraviolet ray is irradiated, the photooxidant 12 in the capsule 11 absorbs the ultraviolet ray hν. The photooxidant 12 that has absorbed the ultraviolet ray hν is activated (activated photooxidant 12a), and radicals are generated (FIG. 3A). The generated radical reacts (oxidizes) with the leuco dye 13, and the leuco dye reacted with the radical develops color (FIG. 3B). As the amount of irradiated ultraviolet light increases, the amount of radicals generated from the photooxidant 12 also increases, and the amount of leuco dye 13 that reacts with the generated radicals also increases.
At the same time as the photooxidant 12 absorbs the ultraviolet ray hν, the reducing agent 13 reacts with the activated photooxidant 12a, and the photooxidant is deactivated (FIG. 2 (b)). As a result, the rate at which radicals react with leuco dyes decreases, so that it is difficult to develop color when the ultraviolet integrated illuminance is small (for example, less than 10 mJ / m ² ). In addition, since the amount of the reducing agent is very small, the proportion of radicals reacting with the leuco dye gradually increases and the color develops when the UV integrated illuminance increases. For this reason, the color density can be continuously changed in accordance with the amount of ultraviolet irradiation as shown in FIG. 1, and the amount of ultraviolet light can be determined visually.
Specific examples and blending amounts of the photooxidant, leuco dye, and reducing agent will be described later.

  Next, the configuration of the ultraviolet ray detection sheet of the present invention will be described. FIG. 4 is a schematic cross-sectional view showing an example of the ultraviolet ray sensing sheet of the present invention. The ultraviolet-sensitive sheet 1 of the present invention includes an ultraviolet-sensitive layer 10 and a support 30 that supports the ultraviolet-sensitive layer 10. Further, a reflective layer (not shown) may be provided between the ultraviolet light sensing layer 10 and the support 30. In the ultraviolet-sensitive layer 10, capsules containing a reducing agent, a photo-oxidizing agent, and a leuco dye as shown in FIG. 2 are dispersed.

Here, the ultraviolet-sensitive sheet of the present invention may be a film having a thickness of 200 μm or less, or may be a sheet exceeding 200 μm. The thickness of the ultraviolet-sensitive sheet of the present invention can be, for example, 5 to 250 μm, and further can be 25 to 150 μm. It may be in the form of a roll obtained by winding a film or the like.
Hereinafter, each layer will be described in detail.

<Ultraviolet sensitive layer>
The ultraviolet-sensitive layer used in the present invention has a capsule containing a photo-oxidant, a leuco dye that can be oxidized and colored by the photo-oxidant, and a reducing agent in a predetermined ratio. The amount of the leuco dye per 1 m ² of the surface area of the ultraviolet-sensitive layer used in the present invention is 0.1 to 1.0 g, preferably 0.15 to 0.8 g, more preferably 0.00. 2 to 0.5 g. By setting it in such a range, it is possible to develop color with high sensitivity corresponding to the irradiation amount of ultraviolet rays more effectively. Details of the capsule will be described later.

The UV-sensitive layer usually contains a binder for dispersing the capsules in the layer, and may contain other additives as necessary. As binders, polyvinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxypropylcellulose, gum arabic, gelatin, polyvinylpyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylate, ethylene-vinyl acetate Various emulsions such as copolymers can be used. The amount is 0.1g / m ² ~5g / m ² in terms of solid content.
Examples of other additives include a reducing agent, a sensitizer, an antioxidant, and a surfactant. Examples of the reducing agent that may be blended outside the capsule of the ultraviolet light sensing layer are the same as those described later. As for the sensitizer and the surfactant, the description in paragraphs 0038 to 0039 and 0048 to 0059 of JP-A No. 12077741, page 9, lower left column to page 10, upper left column and JP-A No. 2004-233614 can be referred to. The contents of which are incorporated herein by reference.

  The thickness of the ultraviolet ray sensing layer is not particularly defined, but is preferably 3 to 30 μm, more preferably 10 to 20 μm, and further preferably 12 to 17 μm.

<< capsule >>
The capsule contained in the ultraviolet light sensing layer used in the present invention contains a photooxidant and a leuco dye at a predetermined mass ratio. The mass ratio of the photooxidant and leuco dye encapsulated in the capsule is 0.2 to 1.0: 1, preferably 0.3 to 0.8: 1, more preferably 0.4 to 0.7: 1. By blending at such a mass ratio, it is possible to more effectively develop color with high sensitivity corresponding to the amount of ultraviolet irradiation. The mass ratio of the photooxidant to the leuco dye is preferably such that the average mass ratio of the photooxidant to the leuco dye for each capsule satisfies the above range, but the photooxidant and leuco per unit area of the UV-sensitive layer. If the average mass ratio of the dye satisfies the above range, the effect of the present invention is exhibited.

  In the capsule contained in the ultraviolet-sensitive layer used in the present invention, the molar ratio of the photooxidant to the reducing agent is 1: 0.01 to 10, preferably 1: 0.05 to 5 and more preferably. 1: 0.1-1. By blending at such a molar ratio, when the UV integrated illuminance is low, color development is difficult, and the effect of the present invention is exhibited. The molar ratio of the photooxidant to the reducing agent is preferably such that the average molar ratio of the photooxidant to the reducing agent in each capsule satisfies the above range. The effect of the present invention is exhibited when the average mole of the above satisfies the above range.

<<< Capsule wall material >>>
The wall material of the microcapsule that can be used in the present invention is not particularly defined as long as it can contain a photooxidant, a leuco dye, and a reducing agent.
For example, polyurethane, polyurea, polyester, polycarbonate, urea-formaldehyde resin, melamine-formaldehyde resin, polystyrene, styrene-methacrylate copolymer, gelatin, polyvinyl pyrrolidone, polyvinyl alcohol and the like can be used. Two or more of these polymer substances can be used in combination.
In the present invention, among the above polymer substances, polyurethane, polyurea, polyamide, polyester, polycarbonate and the like are preferable, and polyurethane and polyurea are particularly preferable.

The capsule wall material used in the present invention is preferably a capsule wall material that prevents contact between the inside and outside of the capsule due to the substance isolating action of the capsule wall at normal temperature and increases the permeability of the substance only when heated to a certain temperature or higher. . When such a capsule wall material is used and a reducing agent is blended outside the capsule, the color of the leuco dye can be fixed by heat.
In this phenomenon, the permeation start temperature can be freely controlled by appropriately selecting the capsule wall material, the capsule core material, and the additive. In this case, the permeation start temperature corresponds to the glass transition temperature of the capsule wall. Specific examples include JP-A-59-190886 and JP-A-60-2421994, and the contents thereof are incorporated in the present specification.

The capsule used in the present invention is preferably encapsulated by emulsifying a core substance containing a reactive substance such as a leuco dye and a photo-oxidant, and then forming a polymer substance wall around the oil droplet. . In this case, the reactant that forms the polymer substance is added to the inside of the oil droplet and / or to the outside of the oil droplet. Details of capsules that can be preferably used in the present invention, such as preferred methods for producing capsules, are described in the specifications of US Pat. Nos. 3,726,804 and 3,796,696, the contents of which are incorporated herein. .
Further, for example, when polyurethane urea is used as a capsule wall material, a polyvalent isocyanate and a second substance that reacts therewith to form a capsule wall (for example, a polyol) are mixed in an aqueous phase or an oily liquid to be encapsulated, By emulsifying and dispersing the temperature, a polymer forming reaction is caused at the oil droplet interface to form a capsule wall. If the second material is, for example, a polyamine or nothing is added, polyurea is formed.

  In this case, for the polyisocyanate to be used and the polyol and polyamine (the above-mentioned second substance) that react with the polyisocyanate, the specifications of US Pat. These are described in JP-B-49-24159, JP-A-48-80191, and JP-B-48-84086, and the contents thereof are also incorporated in the present specification.

  Examples of the polyvalent isocyanate 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′-hyphenyl-diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate, xylylene-1,4-diisocyanate, 4,4′-diphenylpropane diisocyanate, trimethylene Diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4- Diisocyanates such as isocyanate, 4,4 ′, 4′-triphenylmethane triisocyanate, triisocyanates such as toluene-2,4,6-triisocyanate, 4,4′-dimethyldiphenylmethane-2,2 ′, 5,5 Tetraisocyanate such as' -tetraisocyanate, adduct of hexamethylene diisocyanate and trimethylolpropane, adduct of 2,4-tolylene diisocyanate and trimethylolpropane, adduct of xylylene diisocyanate and trimethylolpropane, tolylene diisocyanate Isocyanate prepolymers such as adducts of hexanetriol. As a commercial item, Takenate series (Mitsui Chemicals Co., Ltd. product), such as Takenate D-110N, etc. are mentioned.

Examples of the polyol include aliphatic and aromatic polyhydric alcohols, hydroxy polyesters, hydroxy polyalkylene ethers, and the like.
Specific examples include polyols described in JP-A-60-49991, such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1, 6-hexanediol, 1,7-hebutanediol, 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, 2-phenylpropylene glycol, 1,1,1-to Aromatic polyhydric alcohols such as methylolpropane, hexanetriol, pentaerythritol, pentaerythritol ethylene oxide adduct, glycerin ethylene oxide adduct, glycerin, 1,4-di (2-hydroxyethoxy) benzene, resorcinol dihydroxyethyl ether, and alkylene Condensation products with oxide, p-xylylene glycol, m-xylylene glycol, α, α'-dihydroxy-p-diisopropylbenzene, 4,4'-dihydroxy-diphenylmethane, 2- (p, p'-dihydroxydiphenyl Methyl) benzyl alcohol, bisphenol A to ethylene oxide adduct, bisphenol A to propylene oxide adduct, and the like. The polyol is preferably used at a hydroxyl group ratio of 0.02 to 2 moles per mole of isocyanate groups.

  Examples of the polyamine include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, p-phenylenediamine, m-phenylenediamine, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, and 2-hydroxy. Examples include trimethylenediamine, diethylenetriamine, triethylenetriamine, triethylenetetramine, diethylaminopropylamine, tetraethylenepentamine, and an amine adduct of an epoxy compound. Polyvalent isocyanate can also react with water to form a polymeric material.

Here, the organic solvent for forming the oil droplets can generally be appropriately selected from high boiling oils, L such as tricresyl phosphate, phthalic acid esters such as dibutyl phthalate, acrylic acid esters, methacrylic acid. Esters, other carboxylic acid esters, fatty acid amides such as N, N-diethyldodecanamide, alkylated biphenyl, alkylated terphenyl, chlorinated paraffin, alkylated naphthalene, diarylethane and the like are used. Specifically, those described in JP-A-60-242094 and JP-A-63-045084 can be used, and the contents thereof are incorporated in the present specification.
In the present invention, an auxiliary solvent can be added to the above organic solvent as a solubilizing agent having a lower boiling point. Examples of such auxiliary solvents include ethyl acetate, isopropyl acetate, butyl acetate, and methylene chloride.

On the other hand, the water-soluble polymer contained as a protective colloid in the aqueous phase mixed with the oil phase can be appropriately selected from known anionic polymers, nonionic polymers, and amphoteric polymers. Gelatin and cellulose derivatives are preferred.
In addition, a surfactant may be contained in the aqueous phase. As the surfactant to be contained in the aqueous phase, precipitation or aggregation is caused by acting on the protective colloid from among anionic or nonionic surfactants. Anything that does not occur can be appropriately selected and used.
Preferred surfactants include, for example, sodium alkylbenzene sulfonate (for example, sodium lauryl sulfate), dioctyl sodium sulfosuccinate, polyalkylene glycol (for example, polyoxyethylene nonylphenyl ether), and the like.

  The capsule used in the present invention is usually a microcapsule having an average particle diameter of the order of μm, and the average particle diameter of the capsule is preferably 0.1 to 100 μm, and preferably 0.3 to 10 μm. More preferably, it is 0.5-5 micrometers. When the average particle size is 0.1 μm or more, an effect of stably protecting the core substance in the capsule is obtained, and when the average particle size is 100 μm or less, the effect of improving the resolution of the color former is obtained.

<<< leuco dye >>>>
The leuco dye used in the present invention is a leuco dye that can be colored by a photo-oxidizing agent. One or two leuco dyes that form a dye by adding electrons or removing electrons to form a color. A reduced type dye having one hydrogen atom is meant. By selecting a leuco dye that is substantially colorless or has a weak color before the electrons are removed, it is possible to develop a color by photooxidation. In addition, a leuco dye may be used individually by 1 type, and 2 or more types may be mixed and used for it.

  The leuco dye used in the present invention is, for example, as described in US Pat. No. 3,445,234, (a) aminotriarylmethane, (b) aminoxanthine, (C) aminothioxanthine, (d) amino-9 , 10-dihydroacridine, (e) aminophenoxazine, (f) aminophenothiazine, (g) aminodihydrophenazine, (h) aminodiphenylmethane, (i) leucodamine, (j) aminohydrocinnamic acid (cyanethane, Leucometine), (k) hydrazine, (l) leucoin digoid dye, (m) amino-2,3-dihydroanthraquinone, (n) tetrahalo-p, p'-biphenol, (o) 2- (p-hydroxyphenyl) ) -4,5-diphenylimidazole, (p) phenethylaniline, etc. It can be. Among these leuco dyes, those of (a) to (i) are colored by the loss of one hydrogen atom to become dyes, while those of (j) to (p) lose two hydrogen atoms. Form a dye.

Of these, aminoarylmethane is preferred and aminotriarylmethane is preferred. Generally preferred aminotriarylmethane types are those in which at least two of the aryl groups are
(A) For bonding to a methane carbon atom, wherein R ¹ and R ² are groups selected from hydrogen, an alkyl group having 1 to 10 carbon atoms, a 2-hydroxyethyl group, a 2-cyanoethyl group, and a benzyl group, respectively. An R ¹ R ² N-substituent in the para position, and (b) a lower alkyl group (having 1 to 4 carbon atoms), a lower alkoxy group (having 1 to 4 carbon atoms), a fluorine atom, a chlorine atom, and A phenyl group having a group ortho to the methane carbon atom selected from a bromine atom;
The third aryl group (remaining one aryl group) may be the same as or different from the other two aryl groups, and if different, (a) a lower alkyl group, a lower alkoxy group, a chlorine atom, diphenyl Amino group, cyano group, nitro group, hydroxy group, fluorine atom, bromine atom, alkylthio group, arylthio group, thioester group, alkyl sulfonic acid group, aryl sulfonic acid group, sulfonic acid group, sulfonic amide group, alkyl amide group, aryl A phenyl group which may be substituted with an amide group or the like; (b) an amine group, a di-lower alkylamino group, a naphthyl group which may be substituted with an alkylamino group; or (C) an alkyl group which may be substituted with alkyl. (D) a quinolyl group; (e) an indolinylidene group optionally substituted with an alkyl group. Amino triarylmethane and acid salt characterized in that.
Preferably, R ¹ and R ² are hydrogen or alkyl having 1 to 4 carbon atoms. Most preferably all three aryl groups are identical.

  Specific examples of such leuco dyes include, for example, 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-trifluoro Methylphenyl) -N-ethylamino-6-diethylamino-9- (2-methoxycarbonylphenyl) xanthene, 2- (2-chlorophenyl) amino-6-dibutylamino-9- (2-methoxycarbonylphenyl) xanthene, 2 -Dibenzylamino-6-diethylamino-9- (2-metho Cycarbonylphenyl) xanthene, benzo [a] -6-N, N-diethylamino-9,2-methoxycarbonylphenyl) xanthene, 2- (2-chlorophenyl) -amino-6-dibutylamino-9- (2-methyl) Phenylcarboxyamidophenyl) xanthene, 3,6-dimethoxy-9- (2-methoxycarbonyl) -phenylxanthene, benzoylleucomethylene blue, 3,7-bis-diethylaminophenoxazine and the like. Examples of commercially available products include leuco crystal violet (LCV, manufactured by Yamada Chemical Co., Ltd.).

<<< Photooxidant >>>
The photooxidant used in the present invention is activated by ultraviolet rays to generate radicals. By using such a photo-oxidant, the color density changes continuously according to the amount of ultraviolet irradiation, and the amount of ultraviolet light can be determined visually.
As a photooxidant used in the present invention, ε at a wavelength of 350 nm is preferably 2000 or less, more preferably 1000 or less, and further preferably 500 or less. For example, there are ranges of 320 or less and 280 or less, but it is not limited to this. Further, ε at a wavelength of 250 nm is preferably 10,000 or more, more preferably 11,000 or more, and further preferably 12000 or more. For example, there are a range of 12630 or more and a range of 12740 or more, but the present invention is not limited to this. By setting it as such a range, the ultraviolet-ray detection performance of this invention is exhibited more effectively. Here, ε means the molar extinction coefficient of the photooxidant, and can be measured using, for example, an ultraviolet spectrophotometer.
The photooxidant used in the present invention is preferably a photooxidant represented by the following general formulas (1) to (7). In addition, a photooxidant may be used individually by 1 type and may be used in mixture of 2 or more types.

（式中、Ａ、Ｂ、およびＤは、それぞれ独立に、無置換もしくは、イミダゾリル基への二量体の解離またはロイコ染料の酸化を阻害しない置換基で置換された、炭素環またはヘテロアリール基を表す。） General formula (1)

Wherein A, B, and D are each independently a carbocyclic or heteroaryl group that is unsubstituted or substituted with a substituent that does not inhibit the dissociation of the dimer into an imidazolyl group or the oxidation of a leuco dye. Represents.)

A, B, and D each independently represent a carbocyclic or heteroaryl group that is unsubstituted or substituted with a substituent that does not inhibit the dissociation of the dimer into an imidazolyl group or oxidation of the leuco dye.
B and D each preferably have 0 to 3 substituents, and A preferably has 0 to 4 substituents.
The compound represented by the general formula (1) and the production method thereof can utilize knowledge known as lophine dimer and the like. For example, the description of US Pat. No. 3,552,973, column 4, line 22 to column 6, line 3 can be referred to, and the contents thereof are incorporated in the present specification.

General formula (2)
P ⁰ -CX ₃
(In the formula, P ⁰ represents a hydrogen atom, a halogen atom or an aryl group, and X represents a halogen atom.)

The halogen atom represented by P ⁰ and X is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, preferably a chlorine atom or a bromine atom.

  Examples of the compound represented by the general formula (2) include carbon tetrachloride, carbon tetrabromide, p-nitrobenzotribromide, bromotrichloromethane, pensitrichloride, hexabromoethane, iodoform, 1,1,1. -Tribromo-2-methyl-2-propanol, 1,1,2,2-tetrabromoethane, 2,2,2-tribromoethanol, 1,1,1-trichloro-2-methyl-2-propanol, etc. Can be mentioned.

（式中、Ｒは置換基を表す。ｘは０〜５の整数を表す。） General formula (3)

(In the formula, R represents a substituent. X represents an integer of 0 to 5.)

R represents a substituent, and examples of the substituent 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. Etc. When R has two or more, all the substituents may be the same and may differ.
x represents an integer of 0 to 5, preferably 0 to 3.

  Examples of the compound represented by the 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, α, α, α-tribromo-3,4-cyclochloroacetophenone.

General formula (4)
R ¹ —SO ₂ —X ¹
(In the formula, R ¹ represents an alkyl group which may have a substituent or an aryl group which may have a substituent, and X ¹ represents a halogen atom.)

R ¹ represents an alkyl group which may have a substituent or an aryl group which may have a substituent. The alkyl group which may have a substituent is preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms, and further preferably an alkyl group having 1 to 6 carbon atoms.
As the aryl group which may have a substituent, an aryl group having 6 to 20 carbon atoms is preferable, an aryl group having 6 to 14 carbon atoms is more preferable, and an aryl group having 6 to 10 carbon atoms is more preferable.
Examples of the substituent 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.
The halogen atom represented by X ¹ is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, preferably a chlorine atom or a bromine atom.

  Examples of the compound represented by the general formula (4) include 2,4-dinitrobenzenesulfonyl chloride, o-nitrobenzenesulfonyl chloride, m-nitrobenzenesulfonyl chloride, 3,3′-diphenylsulfone disulfonyl chloride, ethanesulfonyl chloride. P-bromobenzenesulfonyl chloride, p-nitrobenzenesulfonyl chloride, p-3-benzenesulfonyl chloride, p-acetamidobenzenesulfonyl chloride, p-chlorobenzenesulfonyl chloride, p-toluenesulfonyl chloride, methanesulfonyl chloride, Hensensulfonyl bromide, etc. Is mentioned.

General formula (5)
R ² -S-X ²
(Wherein R ² represents an alkyl group which may have a substituent, or an aryl group which may have a substituent, and X ² represents a halogen atom.)

R ² represents an alkyl group which may have a substituent or an aryl group which may have a substituent, and has the same meaning as R ^{1 in} formula (4), and the preferred range is also the same.
The halogen atom represented by X ² is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, preferably a chlorine atom or a bromine atom.

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

（式中、Ｒ³は置換基を有していてもよいアリール基、または置換基を有していてもよいヘテロアリール基を表し、Ｘ³、Ｘ⁴、およびＸ⁵はそれぞれ独立に水素原子、またはハロゲン原子を表す。ただし、Ｘ³、Ｘ⁴、およびＸ⁵のすべてが水素原子であることはない。） General formula (6)

(In the formula, R ³ represents an optionally substituted aryl group or an optionally substituted heteroaryl group, and X ³ , X ⁴ , and X ⁵ are each independently a hydrogen atom. Or a halogen atom, provided that X ³ , X ⁴ , and X ⁵ are not all hydrogen atoms.)

R ³ represents an aryl group which may have a substituent, or a heteroaryl group which may have a substituent.
As the aryl group, an aryl group having 6 to 20 carbon atoms is preferable, an aryl group having 6 to 14 carbon atoms is more preferable, and an aryl group having 6 to 10 carbon atoms is further preferable.
As a heteroaryl group, a C4-C20 heteroaryl group is preferable, a C4-C13 heteroaryl group is more preferable, and a C4-C9 heteroaryl group is further more preferable.
Examples of the substituent 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.
The halogen atom represented by X ³ , X ⁴ and X ⁵ is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, preferably a chlorine atom or a bromine atom.

  Examples of the compound represented by the general formula (6) include hexabromodimethylsulfoxide, pentabromodimethylsulfoxide, hexabromodimethylsulfone, trichloromethylphenylsulfone, tribromomethylphenylsulfone, trichloromethylphenylsulfone, trichloro- p-chlorophenylsulfone, tribromomethyl-p-nitrophenylsulfone, 2-trichloromethylbenzothiazolesulfone, 4,6-cymethylbirimidine-2-tribromomethylsulfone, tetrabromodimethylsulfone, 2,4-dichlorophenyl- Trichloromethylsulfone, 2-methyl-4-chlorophenyltrichloromethylsulfone, 2,5-dimethyl-4-chlorophenyltrichloromethylsulfone, 2,4-dichloropheny Trimethyl sulfone, tribromomethylphenylsulfone, tri -p- tolyl sulfonium trifluoromethanesulfonate and the like.

General formula (7)
R ⁴ CX ⁶ X ⁷ X ⁸
(In the formula, R ⁴ represents a heteroaryl group which may have a substituent, and X ⁶ , X ⁷ and X ⁸ each independently represents a hydrogen atom or a halogen atom, provided that X ⁶ , X ⁷ and X ⁸ are not all hydrogen.)

R ⁴ represents a heteroaryl group which may have a substituent. As a heteroaryl group, a C4-C20 heteroaryl group is preferable, a C4-C13 heteroaryl group is more preferable, and a C4-C9 heteroaryl group is further more preferable.
Examples of the substituent 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.
The halogen atom represented by X ⁶ , X ⁷ and X ⁸ is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, preferably a chlorine atom or a bromine atom.

  Examples of the compound represented by the 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-didochloromethyl-4- (p-methoxyphenyl)-% by weight, 2- (4-methylphenyl) -4,6-bis (trichloromethyl) -1, 3,5-triazine and the like can be mentioned.

  Among these, compounds represented by general formula (3), general formula (6), and general formula (7) are preferable, and chlorine, bromine, and iodine are preferable as the halogen atom. In addition to the compounds represented by the general formulas (1) to (7), diazo compounds such as bis (t-butylsulfonyl) diazomethane may be used.

<<< Reducing agent >>>
The reducing agent used in the present invention is not particularly defined as long as it does not depart from the gist of the present invention, and known ones can be adopted. A reducing agent can be used individually or in combination of 2 or more types.

The reducing agent used in the present invention is not particularly limited as long as it acts as a so-called free radical trapping substance that traps free radicals of the activated photooxidant. For example, organic reduction described in the specification of US Pat. No. 3,425,513 is possible. Agents (for example, hydroquinone, tetramethylbutylhydroquinone, catechol, resorcinol, hydroxyhydroquinone, pyrologrystool, and aminophenols such as 0-aminophenol and p-aminephenol).
In addition to the above, phenolic hydroxyl group-containing compounds that are widely used as antioxidants are preferred, such as p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, 4,4-thiobis. Selected from the group consisting of (3-methyl-6-t-butylphenol), 2,2′-methylenebis (4-methyl-6-t-butylphenol), polysubstituted phenolic compounds, phenolic resins, and cresol resins. And the like.
Representative examples that can be obtained as commercially available products include, for example, Sumilizer BHT, BBM-S (manufactured by Sumitomo Chemical), Irganox 245, 1010, 1076, 1222 (manufactured by BASF), ADK STAB AO-20, AO-30, AO-40, AO -50, AO-60 (manufactured by ADEKA), etc., and Adeka Stub AO-80 (manufactured by ADEKA).
In addition, the cyclic phenylhydrazide compounds described in the specification of JP-B-62-39726 (for example, 1-phenylpyrazolidine-3-one [phenidone A, the following formula (1]), 1-phenyl-4 -Methyl virazolidin-3-one [phenidone B, the following formula (2)], 1-phenyl-4,4-dimethylpyrazolidin-3-one [dimazone, the following formula (3)], and 3 -Methyl-1-p-sulfophenyl) -2-pyrazolin-5-one and 3-methyl-1-phenyl-2-virazolin-5-one). Examples of commercially available products include 4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidinone (Dimezone S, manufactured by Daito Chemical Co., Ltd.).

The phenyl group of cyclic phenylhydrazide may have a substituent, and examples of the substituent include a methyl group, a trifluoromethyl group, a chlorine atom, a bromine atom, a fluorine atom, a methoxy group, an ethoxy group, and p-benzyl. Examples thereof include an oxy group, a butoxy group, a p-phenoxy group, a 2,4,6-trimethyl group and a 3,4-dimethyl group.
The heterocyclic group of the cyclic phenylhydrazide may have a substituent at the 4-position, and examples of the substituent include a bis-hydroxymethyl group, a hydroxymethyl group, a methyl group, an ethyl group, and a benzyl group. .
The heterocyclic group of the cyclic phenylhydrazide may have a substituent at the 5-position, and examples of the substituent include a methyl group and a phenyl group.

Further, the reducing agent may be a guanidine derivative, an alkylenediamine derivative, or a hydroxyamine derivative.
Examples of guanidine visiting conductors include phenylguanidine, 1,3-diphenylguanidine, 1,2,3-triphenylguanidine, 1,2-dicyclohexylguanidine, 1,2,3-tricyclohexylguanidine, 1,3-di -O-tolylguanidine, o-tolyldiphenylguanidine, m-tolyldiphenylguanidine, p-tolyldiphenylguanidine, N, N'-dicyclohexyl-4-morpholinocarboxyamidine, 1,3-ditolyl-3-phenylguanidine, 1, Examples include 2-dicyclohexylphenylguanidine, 1-o-tolylbiguanide, N-benzylidene-guanidinoamine, and the like.
Examples of the alkylene diamine derivative include ethylene diamine, propylene diamine, tetramethylene diamine, hexamethylene diamine, octamethylene diamine, 1,1,2-diaminododecane, and tetrabenzylethylene diamine.
Examples of the hydroxyamine derivative include diethanolamine, triethanolamine, 3-β-naphthyloxy-1-N, N dimethylamino-2-propanol, and the like.

In the sheet of the present invention, the reducing agent is preferably solid-dispersed by a sand mill or the like, or emulsified and dispersed after being dissolved in oil.
In the case of solid dispersion, it is dispersed in a water-soluble polymer solution having a concentration of 2 to 30% by mass, and a preferable dispersed particle size is 10 μm or less. Preferred water-soluble polymers include water-soluble polymers used when making capsules. The emulsification and dispersion can be performed with reference to the technique and materials described in JP-A-63-045084.

<< Method for forming UV-sensitive layer >>
The UV-sensitive layer can be prepared by applying, impregnating, or forming a self-supporting layer on a support or a reflective layer as a dispersion of capsules containing the above-described leuco dye and photooxidant.
The coating amount of the ultraviolet sensitive layer coating solution for forming the UV-sensitive layer is preferably 3g / m ² ~30g / m ² in terms of solid ^{content, 5g / m 2 ~20g / m} 2 is more preferable. If it is 3 g / m ² or less, a sufficient concentration cannot be obtained, and even if it is applied at 30 g / m ² or more, no improvement in quality is seen, which is disadvantageous in terms of cost.

  In applying the UV-sensitive layer coating solution, generally well-known coating methods such as dip coating, air knife coating, curtain coating, roller coating, doctor coating, wire pernite, slide coating It can be applied by a method, a gravure coating method, a spin neat method, or an extrusion coating method using a hopper described in US Pat. No. 2,681,294.

<Support>
The support used in the present invention is not particularly limited as long as it does not depart from the spirit of the present invention.
Suitable materials for the support include films made of plastics and polymers such as paper, regenerated cellulose, cellulose acetate, cellulose nitrate, polyethylene terephthalate, vinyl polymers and copolymers, polyethylene, polyvinyl acetate, polymethyl methacrylate, polyvinyl chloride. Woven fabrics; including materials commonly used in graphic arts and decorative applications such as glass, wood and metal.

  As thickness of a support body, 5-250 micrometers is preferable, 25-150 micrometers is more preferable, 50-100 micrometers is further more preferable.

<Reflective layer>
In the present invention, a reflection layer may be provided between the support and the ultraviolet light sensing layer, and the reflection density can be improved by providing the reflection layer. When the support itself has a reflection function, a reflection layer is not necessary. However, when the support is transparent, it is preferable to provide a reflection layer to suppress light transmission.

The reflective layer in the present invention is preferably formed on one surface of the support and contains a binder and white inorganic particles. The ratio of the white inorganic particles contained in the reflective layer is preferably 30% by mass to 90% by mass with respect to the total mass of the binder and the white inorganic particles in the reflective layer.
The reflective layer may further include other components such as various additives as necessary.

<< white inorganic particles >>
The reflective layer in the present invention preferably contains at least one kind of white inorganic particles. The white inorganic pigment may be the same as or different from the white inorganic particles contained in the polymer substrate. For example, titanium dioxide, barium sulfate, silicon oxide, aluminum oxide, magnesium oxide, calcium carbonate, kaolin, talc, etc. These inorganic pigments can be appropriately selected and contained. Of these, titanium dioxide is preferable. Examples of commercially available products include, for example, a Taipei series such as Taipei R780-2 (manufactured by Ishihara Sangyo Co., Ltd.).

  The reflective layer in the present invention preferably contains 30% by mass to 90% by mass of white inorganic particles, and more preferably 50% by mass to 85% by mass with respect to the total mass of the binder and the white inorganic particles in the reflective layer. If the content of the white inorganic particles in the reflective layer is not 30% by mass or more, good reflectance cannot be obtained, and if it is not 90% by mass or less, weight reduction cannot be achieved.

The reflective layer in the present invention preferably contains white inorganic particles at 4 to 12 g / m ² , and more preferably 5 to 11 g / m ² . When the content of the white inorganic particles is 4 g / m ² or more, the required reflectance is easily obtained, and when the content is 12 g / m ² , the weight of the sheet of the present invention can be easily reduced.

  The average particle size of the white inorganic particles is preferably 0.1 to 10 μm, more preferably about 0.3 to 8 μm in terms of volume average particle size. When the average particle size is within the above range, the light reflection efficiency is high. The average particle diameter is a value measured by a laser analysis / scattering particle size distribution measuring apparatus LA950 (manufactured by Horiba, Ltd.).

<< Binder >>
The reflective layer in the present invention preferably contains at least one binder. The coating amount of the binder is preferably in the range of 0.5 to 5.0 g / m ^2, the range of 1 to 3 g / m ² is more preferable. When the coating amount of the binder is 0.5 g / m ² or more, the strength of the reflective layer is sufficiently obtained, and when it is 5 g / m ² or less, the reflectance and the mass can be kept good.
Binders suitable for the reflective layer in the present invention are polyvinyl alcohol (PVA), modified polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, epichlorohydrin modified polyamide, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, Examples thereof include isobutylene-maleic salicylic anhydride copolymer, polyacrylic acid, polyacrylic amide, methylol-modified polyacrylamide, starch derivative, casein, and gelatin. Further, for the purpose of imparting water resistance to these binders, a water resistance improver may be added, or an emulsion of a hydrophobic polymer, specifically, an acrylic resin emulsion, a styrene-butadiene latex or the like may be added. As a binder to be used, polyvinyl alcohol is preferable from the viewpoint of improving transparency, and modified PVA such as carboxy-modified polyvinyl alcohol and alkyl ether-modified polyvinyl alcohol can also be used.

<< Additives >>
In addition to the binder and the white inorganic particles, the reflective layer in the present invention can further contain other components as necessary. Other components are not particularly limited and can be appropriately selected depending on the purpose or necessity. Examples of other components include a crosslinking agent, a surfactant, and a filler.
As a crosslinking agent, it can select suitably from well-known crosslinking agents. For example, water-soluble initial condensates such as N-methylol urea, N-methylol melamine, urea-formalin; dialdehyde compounds such as glyoxal and glutaraldehyde; inorganic crosslinking agents such as boric acid and borax; polyamide epichlorohydrin and the like .
Among the binders, when a water-soluble polymer compound (for example, gelatin or polyvinyl alcohol) is used, the storage stability can be further improved by containing a crosslinking agent and crosslinking the binder.
When the crosslinking agent is added, the addition amount is preferably 5 to 50% by mass and more preferably 10 to 40% by mass with respect to the binder in the reflective layer. When the addition amount of the crosslinking agent is 5% by mass or more, a sufficient crosslinking effect can be obtained while maintaining the strength and adhesiveness of the reflective layer, and when it is 50% by mass or less, the pot life of the coating solution can be kept long.

Examples of the surfactant include known surfactants such as anionic and nonionic surfactants. If a surfactant is added, the addition amount thereof is preferably from ^{0.1~15mg / m 2, 0.5~5mg / m} 2 is more preferable. When the addition amount of the surfactant is 0.1 mg / m ² or more, generation of repellency is suppressed and good layer formation is obtained, and when it is 15 mg / m ² or less, adhesion can be performed satisfactorily.

  In addition to the white inorganic particles, a filler such as silica may be added to the reflective layer in the present invention. When adding a filler, the addition amount is preferably 20% by mass or less, and more preferably 15% by mass or less with respect to the binder in the reflective layer. When the addition amount of the filler is 20% by mass or less, necessary reflectance and adhesion to the support can be obtained.

<Method for forming reflective layer>
The reflective layer of the present invention is formed by applying the reflective layer coating liquid containing the white inorganic particles, the binder, and other additives to at least one surface of the support.

As a coating method, for example, a known coating method such as a gravure coater or a bar coater can be used.
The coating solution may be an aqueous system using water as an application solvent, or a solvent system using an organic solvent such as toluene or methyl ethyl ketone. Among these, from the viewpoint of environmental burden, it is preferable to use water as a solvent. A coating solvent may be used individually by 1 type, and may mix and use 2 or more types. Examples of preferable coating solvents include water, water / methyl alcohol = 95/5 (mass ratio), and the like.
In the application of the reflective layer coating solution, the reflective layer coating solution is applied directly on the surface of the polymer substrate or through an undercoat layer having a thickness of 2 μm or less, and the reflective layer is formed on the polymer substrate. Can be formed.
The coating amount of the reflective layer coating solution, 5 g / m ² or more is preferable in terms of solid content, 10 g / m ² or more is more preferable. Although there is no restriction | limiting in particular about an upper limit, It is 30 g / m < ² > or less. If it is 5 g / m ² or less, a sufficient reflection density cannot be obtained.

  The thickness of the reflective layer is preferably 5 to 30 μm, more preferably 7 to 20 μm, and even more preferably 9 to 15 μm.

<Ultraviolet light detection method>
Since the ultraviolet-sensitive sheet of the present invention can continuously develop colors according to the integrated illuminance of ultraviolet rays, the amount of ultraviolet rays can be confirmed and detected visually. In particular, due to excellent ultraviolet sensing in the range of ^{10mJ / cm 2 ~10000mJ / cm 2} , it can be widely used as an ultraviolet detection method or an ultraviolet measuring method. Moreover, since it is in the form of a sheet or film, it is possible to measure the amount of ultraviolet irradiation over a wide area.
Since the ultraviolet ray detection sheet of the present invention is in the form of a sheet or a film, it is possible to measure ultraviolet rays simply by placing it on a place where ultraviolet rays are desired to be measured.

<Application of UV sensing sheet>
UV sensitive sheet of the present invention, it is possible to check the amount of ultraviolet light visually, a simple measurement of the amount of UV irradiation of a large area, in particular, the UV sensitive in the range of 10mJ / cm ² ~10000mJ / cm ² Since it is excellent, it can be used in various applications. For example, when manufacturing a film while UV curing resin is UV cured with roll-to-roll, it can be used to measure the amount of UV light that is irradiated with an UV irradiation device without using an UV light meter. is there. In addition, for example, in order to grasp the degree of sunburn caused by ultraviolet rays of a person or an object, it is possible to measure the amount of ultraviolet rays during the day.

  The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like 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 is not limited to the specific examples shown below. The “part” indicating the added amount indicates “part by weight”.

(Preparation of UV detection sheet)
[Example 1]
A mixed solution having the following composition was added to an aqueous solution consisting of 63 parts of an 8% by weight aqueous polyvinyl alcohol solution and 100 parts of distilled water, and then emulsified and dispersed at 20 ° C. to obtain an emulsion having a volume average particle diameter of 1 μm. Further, the obtained emulsion was continuously stirred at 40 ° C. for 3 hours. Thereafter, the temperature was returned to room temperature, followed by filtration to obtain an aqueous capsule dispersion.
-Composition of the mixture-
Leuco dye: Leuco Crystal Violet (LCV, manufactured by Yamada Chemical Co., Ltd.)
3.0 parts photo-oxidant: tribromomethylphenyl sulfone (BMPS, manufactured by Sumitomo Seika Co., Ltd.) 1.5 parts reducing agent: tetramethylbutyl hydroquinone (manufacturer: Wako Pure Chemical Industries) 0.75 parts methylene chloride 22 parts tricre Zilphosphate 24 parts Takenate D-110N (75% by mass ethyl acetate solution, Mitsui Chemicals, Inc.) 24 parts

Next, a mixed liquid having the following composition was dispersed with Dynomill (manufactured by Willy A. Bacofen AG) to obtain a Dimaison S dispersion having an average particle diameter of 3 μm.
-Composition of the mixture-
Polyvinyl alcohol 4 mass% aqueous solution 150 parts Reducing agent: 4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidine (manufacturer: Daito Chemical Co., Ltd., product number: Dimaison S) 9 parts of the prepared capsule dispersion and Dimaison S Mix 9 parts of the dispersion, apply it to a 75 μm thick foamed polyethylene terephthalate base (Chrisper K1212 manufactured by Toyobo Co., Ltd.) to a solid coating amount of 10 g / m ^2, and heat-dry at 50 ° C. for 1 minute. The UV sensitive film of Example 1 was prepared.

[Example 2]
An ultraviolet-sensitive film was produced in the same manner as in Example 1 except that 0.75 part of the reducing agent in Example 1 was changed to 0.045 part.

[Example 3]
An ultraviolet-sensitive film was prepared in the same manner as in Example 1 except that 0.75 part of the reducing agent in Example 1 was changed to 12 parts.

[Example 4]
The same procedure as in Example 1 was conducted except that the reducing agent tetramethylbutylhydroquinone of Example 1 was changed to stearyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (manufactured by BASF, Irganox 1076). An ultraviolet sensitive film was prepared.

[Example 5]
Except for changing the reducing agent tetramethylbutylhydroquinone of Example 1 to tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane (manufactured by BASF, Irganox 1010). Prepared an ultraviolet-sensitive film in the same manner as in Example 1.

[Example 6]
A UV-sensitive film was prepared in the same manner as in Example 1 except that the photooxidant tribromomethylphenyl sulfone in Example 1 was changed to tri-p-trisulfonium trifluoromethanesulfonate (TS-01, manufactured by Sanwa Chemical Co., Ltd.). Produced.

[Example 7]
An ultraviolet-sensitive film was prepared in the same manner as in Example 1 except that the photooxidant tribromomethylphenylsulfone of Example 1 was replaced with bis (t-butylsulfonyl) diazomethane (Wako, WPAG-170).

[Comparative Example 1]
An ultraviolet-sensitive film was prepared in the same manner as in Example 1 except that 0.5 part of the reducing agent in Example 1 was changed to 0.0075 part.

[Comparative Example 2]
An ultraviolet-sensitive film was produced in the same manner as in Example 1 except that 0.5 part of the reducing agent in Example 1 was changed to 30 parts.

[Measurement of ε (photosensitive area) of photo-oxidant]
Each ε (molar extinction coefficient) at wavelengths of 250 nm and 350 nm was measured with a spectrophotometer (U-2000, manufactured by Hitachi High-Tech).

(Evaluation)
The gradation, handleability, image storability, and reflection density change ΔD of the produced UV sensing films of Examples and Comparative Examples were measured and evaluated as follows. The results are shown in the table below.

[Reflection density change]
A high pressure mercury lamp (a high pressure UV lamp, manufactured by Ushio Inc.) was irradiated with ultraviolet rays to the integrated illuminance is ^{1mJ / cm 2, 10mJ / cm} 2, 100mJ / cm 2, 1000mJ / cm 2, and 10000 mJ / cm ^2, The color change at that time was measured with a reflection densitometer (X-Rite 310, manufactured by X-Rite), and the color density at that time was shown. Specifically, 1 mJ / cm ² or more 10 mJ / reflection density changes in the range of less than the reflection density change Derutadi0,10mJ / cm ² or more 100 mJ / cm ² in cm ² less than the range Derutadi1,100mJ / cm ² or more 1000 mJ / cm ² together showing the reflection density variation ΔD3 in reflection density change .DELTA.D2, and 1000 mJ / cm ² or more 10000 mJ / cm ² or less in the range in the range of less than, and evaluated according to the following criteria.
A: Any change in reflection density is 0.2 or more B: Change in reflection density is less than 0.2

[Preservation of dark place]
After leaving in a dark place at 60 ° C. for 3 days, the color density was measured with a reflection densitometer (X-Rite 310, manufactured by X-Rite) and evaluated according to the following criteria.
A: 0.2 or less B: More than 0.2 and 0.3 or less C: More than 0.3

[Color development]
Irradiate 1000 mJ / cm ² with a high pressure mercury lamp (high pressure UV lamp, manufactured by USHIO INC.), Measure the color density at that time with a reflection densitometer (X-Rite 310, manufactured by X-Rite), and Evaluated by criteria.
A: Greater than 0.7 B: Greater than 0.5 and 0.7 or less C: 0.5 or less

As seen, the ultraviolet sensitive sheet of the present invention, it can be seen that excellent ultraviolet ray quantity measured at a range of ^{10mJ / cm 2 ~10000mJ / cm 2} .

DESCRIPTION OF SYMBOLS 1 Ultraviolet sensitive sheet 10 Ultraviolet sensitive layer 11 Capsule 12 Photooxidant 12a Activated photooxidant 13 Leuco dye 14 Reducing agent 30 Support body

Claims (13)

A capsule containing a photo oxidant and a leuco dye capable of being oxidized and colored by the photo oxidant and a reducing agent, wherein the mass ratio of the photo oxidant to the leuco dye is 0.2 to 1.0: 1; An ultraviolet-sensitive sheet having an ultraviolet-sensitive layer in which the molar ratio of the reducing agent is 1: 0.01 to 10 and the amount of leuco dye per 1 m ² of the surface area of the ultraviolet-sensitive layer is 0.1 to 1.0 g. The ultraviolet-sensitive sheet according to claim 1, wherein the reducing agent encapsulated in the capsule is a phenol-based antioxidant. The ultraviolet-sensitive sheet according to claim 1 or 2, wherein the photooxidant has an ε at a wavelength of 350 nm of 2000 or less and an ε at a wavelength of 250 nm of 10,000 or more (where ε is the molar absorption of the photooxidant). Means coefficient.) The ultraviolet-sensitive sheet according to any one of claims 1 to 3, wherein the capsule is a microcapsule. The ultraviolet-sensitive sheet according to any one of claims 1 to 4, wherein the leuco dye is aminoarylmethane. 6. The ultraviolet ray can be detected in a range of 10 to 10000 mJ / cm ² when the ultraviolet ray detection sheet is irradiated with a high-pressure mercury lamp and measured at a wavelength of 365 nm. UV sensitive sheet. The ultraviolet-sensitive sheet according to claim 1, further comprising an ultraviolet-sensitive layer on the support. The ultraviolet-sensitive sheet according to claim 7, wherein the support is a plastic film. Upon irradiation with a high pressure mercury lamp, reflection in the range of less than the reflection density change ΔD1,100mJ / cm ² or more 1000 mJ / cm ² cumulative illuminance in the range of less than 10 mJ / cm ² or more 100 mJ / cm ² at the time when measured at a wavelength of 365nm concentration change .DELTA.D2, and 1000 mJ / cm ² or more 10000 mJ / cm reflection density variation in the ^two following ranges ΔD3 is at respectively 0.2 or more, the ultraviolet sensitive sheet according to any one of claims 1 to 8. The reflection density change ΔD0 is less than 0.2 when the integrated illuminance is 1 mJ / cm ² or more and less than 10 mJ / cm ² when measured at a wavelength of 365 nm when irradiated with a high-pressure mercury lamp. The ultraviolet-sensitive sheet according to claim 1. On the support, a capsule containing a photooxidant, a leuco dye that can be oxidized and colored by the photooxidant, and a reducing agent is included, and the mass ratio of the photooxidant to the leuco dye is 0.2 to 1.0: 1 and the amount of the leuco dye per 1 m ² of the surface area of the support is 0.1 to 1.0 g in an ultraviolet-sensitive layer composition in which the molar ratio of the photooxidant to the reducing agent is 1: 0.01 to 10. The manufacturing method of the ultraviolet-sensitive sheet including applying so that it may become. The method for producing an ultraviolet-sensitive sheet according to claim 11, wherein the ultraviolet-sensitive sheet is the ultraviolet-sensitive sheet according to claim 1. An ultraviolet ray sensing method at an ultraviolet ray integrated illuminance of 10 to 10,000 mJ / m ² , wherein the ultraviolet ray sensing sheet according to claim 1 is used.

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