JPH10157294A - Thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording material having no double colors by providing satisfactory storage stability before recording, stable recording image, fixability and handleability in a bright room, and its recording method. SOLUTION: In the recording material comprising an optical free radical generating agent for generating free radical by absorbing light, and optical color erasing element containing dye to be erased by the radical generated from the agent on the same surface of a support, the agent contains at least one type of acyl phosphorus oxide derivatives represented by a formula I or a formula II (where R<1> to R<6> indicate substituted or non-substituted saturated or unsaturated alkyl group, alkoxy group, aryl group, amino group, heterocyclic group or halogen atom, which may be the same or different from each other. R<2> and R<3> may be coupled to form a ring).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photo-decolorable thermosensitive recording material.

[0002]

2. Description of the Related Art A thermosensitive recording material generally comprises a support having thereon a thermosensitive recording layer mainly composed of an electron-donating, usually colorless or pale-colored leuco dye and an electron-accepting developer. By heating with a thermal head, a hot pen, a laser beam or the like, the leuco dye and the developer react instantaneously to obtain a recorded image. For example, it is disclosed in JP-B-43-4160 and JP-B-45-14039.

[0003] Unlike a system using a silver salt, such a heat-sensitive recording material does not require a wet treatment, so that no waste liquid is generated, recording can be obtained with a relatively simple apparatus, and maintenance is easy. It has advantages such as no noise generation, and is used in a wide range of fields such as measurement recorders, facsimile machines, printers, computer terminals, labels, and vending machines for tickets.

However, ordinary thermosensitive recording materials have a problem that recording can be performed by performing thermal recording again after thermal recording, that is, falsification is easy. There has been a demand for a thermosensitive recording material having the same. In addition, there are also problems such as the generation of color due to storage, that is, the occurrence of background fog, and insufficient image storability.

Many studies have been made to improve these problems. Regarding the fixing property, for example, as shown in JP-A-60-264279, the inside of a microcapsule containing one of the components causing a color-forming reaction is photopolymerized to prevent mixing of the color-forming components. There is a way to fix it. Also, Japanese Patent Application Laid-Open No.
No. 58 discloses a method in which a developer having photopolymerizability is arranged outside a microcapsule containing a leuco dye, and fixing is performed by preventing mixing of a coloring component by photopolymerization. However, in these methods, it is difficult to completely suppress the movement and mixing of the color forming components, and the fixing is insufficient.

As for the fixing property, a method of performing color-sensitive thermal recording using a diazonium salt is also disclosed in, for example,
It has been known for a long time as described in JP-A-7-205190. According to this method, fixing is possible in principle, but the stability of the diazonium salt is not good,
There are various problems, such as the occurrence of ground fog before recording and the reduction of the maximum density.

For the purpose of improving image storability, for example, as disclosed in Japanese Patent Application Laid-Open No. Sho 61-152485, an attempt has been made to microencapsulate a part of a material. However, even with the above-mentioned method, since a leuco compound is used as a coloring material in the first place, the image storability has not yet reached a sufficient level. Various recording methods using coloring materials other than leuco compounds have been proposed, but extremely high heat energy is required for recording, a pure color tone cannot be obtained, production cost is high, and ground fog is large. At present, it has hardly been put to practical use.

As described above, in the heat-sensitive recording material, problems such as the preservability before recording, the stability of the recorded image, and the fixability remain unsolved.

On the other hand, most of the conventional research has been made on color-developing type thermal recording, and there has been little research on decoloring type thermal recording materials. In coloring type thermal recording, not all of the material is involved in coloring. For this reason, in order to obtain a high optical density, a large amount of coloring material is required. On the other hand, in the decoloring type thermal recording, since a pure color forming body can be used, a high optical density can be realized with a small film thickness, and as a result, high sensitivity and high quality image quality can be expected.

As an example of a method of obtaining an image by such a decoloring type, for example, Japanese Patent Application Laid-Open No. 63-227375 discloses a color former composed of a basic dye precursor and a developer, and a method of decolorizing the color former. A method using microcapsules containing a coloring compound is shown. However, a color former comprising a basic dye precursor and a color developer is unstable, and it is difficult to obtain a high color density. In addition, it has a drawback such as discoloration by a plasticizer or the like. JP-A-2-190383, JP-A-2-190385, JP-A-2-19038
No. 6 discloses a method using an organic boron compound anion salt of an organic cationic dye compound. However, organic cationic dye compounds generally have low light fastness,
In this method, the wavelength of light for decoloring depends on the absorption wavelength of the organic cationic dye, that is, only visible light can be used. Therefore, there are drawbacks such that the handling of the material in a bright room is impaired, and a relatively inexpensive and high-output ultraviolet light generating light source cannot be used. In addition, there is a disadvantage that the dye is extremely expensive and does not have high solubility in an organic solvent, so that it cannot be used at a sufficiently high concentration by emulsification and dispersion.

Based on this idea, the present inventors have
In the decolorization type thermal recording, the above-mentioned problems are solved by a combination of a color dye having sufficient fastness and a photo-radical generator that generates free radicals by absorbing light. This is shown in Japanese Patent Application No. 8-137866.

However, it has been found that, in the above-described combination of the color-forming dye and the photo-free radical generator, after the decoloring reaction occurs once, a slight recoloring is observed with the passage of time.

[0013] Then, as a result of further various studies on the combination of a coloring dye and a photo-free radical generator, it was found that such a problem could be solved by a specific photo-free radical generator, and the present invention was reached.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to provide good preservability before recording, stable recorded images, good fixability, handling in a bright room, and a decoloring portion. An object of the present invention is to provide a thermosensitive recording material without recoloring.

[0015]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photo-radical generator which absorbs light to generate free radicals on a support, and which is decolorized by the free radicals generated by the photo-radical generator. In a recording material provided with a photo-decoloring element containing a dye on the same surface, the photo-free radical generator is represented by the following general formula 1 or 2
This was achieved by using a recording material characterized by containing at least one acylphosphor oxide derivative represented by the following formula:

[0016]

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In the formula, R ^{1 to} R ⁶ represent a substituted or unsubstituted saturated or unsaturated alkyl group, alkoxy group, aryl group, amino group, heterocyclic group or halogen atom, which are the same or different. Is also good. R ² and R ³ may be linked to each other to form a ring.

The alkyl group represented by R ^{1 to} R ⁶ in the formula may be linear or branched, and may be further substituted with a suitable group (eg, a halogen atom, an alkoxy group, etc.). . It preferably has 1 to 10 carbon atoms,
Examples include a methyl group, an ethyl group, an n-propyl group, an n-hexyl group, a trichloromethyl group, a vinyl group and the like.

The alkoxy groups represented by R ^{1 to} R ⁶ in the formula may be linear or branched, and may be further substituted with a suitable group (eg, a halogen atom, an alkoxy group, etc.). . It preferably has 1 to 10 carbon atoms,
For example, methoxy group, ethoxy group, n-propoxy group, n
-Hexyloxy group and the like.

The aryl group represented by R ^{1 to} R ⁶ in the formula is preferably an aromatic group such as a phenyl group and a naphthyl group, and these aromatic groups are suitable groups (for example, a halogen atom, an alkyl group, an alkoxy group). Group, nitro group, etc.).

In the formula, the amino group represented by R ^{1 to} R ⁶ is, for example, an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an n-hexyl group, a trichloromethyl group or a vinyl group, a phenyl group, a naphthyl group or the like. It may be substituted with an aryl group, an acyl group such as acetyl, benzoyl and the like.

The heterocyclic groups represented by R ^{1 to} R ⁶ in the formula are substituted or unsubstituted, for example, pyridyl, furyl, thienyl and the like.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the acyl phosphorus oxide derivatives represented by the general formulas 1 and 2 according to the present invention are shown below.
These can be used alone or in combination of two or more.

[0024]

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[0025]

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[0026]

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[0027]

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[0028]

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These acylphosphorus oxide derivatives may be used depending on necessity such as decoloring property and fixing property, but are used in an amount of about 0.5 to 50 moles, more preferably about 1 to 10 moles, per mole of the dye used. It is preferable to use

The wavelength of the light for generating free radicals from the photo-free radical generator can be freely selected depending on the structure of the generator and the combination of the optical sensitizer, but it can be handled in a bright room. In order to achieve this, it is preferable to select a wavelength from ultraviolet to near ultraviolet, and the acyl phosphorus oxide derivative according to the present invention efficiently generates free radicals in this wavelength region.

In the present invention, the photo-free radical generator generates free radicals by excitation by light absorption.
Other photoradical generators can be used in combination with the acylphosphorus oxide derivative according to the present invention. For example, Chapter 1 of “Photopolymer Technology” (edited by Ao Yamaoka and Mototaro Nagamatsu, Nikkan Kogyo Shimbun, 1988) and “Ultraviolet Curing System” (by Kiyomi Kato, General Technology Center, 19)
(1989) The one described in Chapter 5 can be used. Specifically, for example, benzoin derivatives, xanthone derivatives, diketone derivatives, quinone derivatives, biimidazole derivatives, organic polyhalogen compounds, disulfides,
Diazo compounds and the like can be mentioned, but benzoin derivatives, xanthone derivatives, diketone derivatives, quinone derivatives, diazo compounds and the like are preferable in that free radicals are efficiently generated in a wavelength region from ultraviolet to near ultraviolet. An example is shown below.

[0032]

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[0033]

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[0034]

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[0035]

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These photo-free radical generators differ depending on the necessity of decoloring property, fixing property, etc., but preferably used in an amount of 0.1 to 10 times the molar amount of the acyl phosphorus oxide derivative used. preferable.

Various dyes such as diarylmethane dyes, triarylmethane dyes, polymethine dyes and azomethine dyes can be used as the dye which is decolorized by the free radical generated by the photo-free radical generator used in the present invention. Specifically, for example, the dyes described in “Dye Handbook” (edited by Shin Okawara et al., Kodansha, 1986) can be mentioned. Among these, azomethine dyes are preferred from the viewpoints of color tone, light fastness, heat resistance, molecular extinction coefficient, production cost, and the like, and azomethine dyes of the type used in silver halide color photography are particularly preferred. An example is shown below. In the present invention, these dyes can be used alone or in combination of two or more.

The following are specific examples of the diarylmethane dye used in the present invention. Diphenylmethylium chloride, (2-thienyl) phenylmethylium chloride, bis- (p-dimethylaminophenyl) methylium chloride.

Specific examples of the triarylmethane dye used in the present invention include the following.
Aurin, bis (p-dimethylaminophenyl) phenylmethylium chloride, bis (p-dimethylaminophenyl) -p-cyanophenylmethylium chloride,
Tris (p-dimethylaminophenyl) methylium chloride, (p-methylphenyl) diphenylmethylium
Chloride, bis (2-thienyl) phenylmethylium
Chloride, tris (2-thienyl) methylium perchlorate.

The polymethine dye used in the present invention includes various dyes such as cyanine dye, merocyanine dye, oxonol dye and the like.

Specific examples of the cyanine dye include the following. 3,3'-diethyl-2,2 '
-Thiacyanine iodide, 3,3'-diethyl-9-
Methyl-2,2'-thiacarbocyanine iodide,
3,3'-diethyl-2,2'-oxacarbocyanine iodide, 3,3'-diethyl-2,2'-thiaoxacarbocyanine iodide, 3,3 ', 10-trimethyl-2,2'-thio Azicarbocyanine chloride,
3,3'-diethyl-2,2'-oxadicarbocyanine iodide, 1,3'-diethyl-2,2'-quinothiacyanine iodide, 1,1'-diethyl-2,2 '
Quinocyanine iodide, 1,1'-diethyl-2,
2′-quinocarbocyanine iodide, 1,1′-diethyl-4,4′-quinocarbocyanine iodide, 1,
1 ', 3,3,3', 3'-hexamethyl-2,2'-
Indian carbocyanine iodide.

The following are specific examples of other polymethine dyes.

[0043]

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Specific examples of the azomethine dye used in the present invention include the following.

[0045]

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[0046]

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[0047]

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These dyes vary depending on their necessity, such as their molar extinction coefficient and the quality required of the recording material.
Preferably, amounts of 0.1 to 2 mmol per square meter are used.

In one embodiment of the present invention, the various types of dyes and photo-radical generator described above are separated in advance and mixed by heat during recording to form a latent image. Then, when light is applied, in the latent image portion, the free radical generated from the free radical generator reacts with the dye to decolor the dye. On the other hand, the portion to which heat is not applied is a result of the free radical generating agent being photolyzed alone and the ability to generate free radicals being lost, so that the decoloring phenomenon does not occur even when heat is applied again, that is, the portion is fixed. Will be. According to this method, a so-called negative image is produced, in which the heat-recorded area is erased.

In another embodiment of the present invention, the dye and the photo-free radical generator are mixed in advance, and a compound that inhibits the decolorizing action of the photo-free radical generator when separated from these (hereinafter, referred to as a compound). A quencher). The dye, the photoradical generator and the quencher are mixed by the heat during recording to form a latent image. Then, when light is applied, in the latent image portion, the decolorizing action of the free radical generator is inhibited by the action of the deactivator, so that the dye remains in a color-developed state. On the other hand, the part to which heat is not applied, due to the action of the free radical generator,
The dye will be decolorized. At the same time, even if the heat is applied again to the unheated portion, the dye is already decomposed and decolored, so that the color development phenomenon does not occur, that is, the portion is fixed. According to this method, a so-called positive image is generated in which the color recorded state is maintained at the place where heat recording is performed.

The quenching agent in the present invention stops the decolorizing effect on the dye due to free radicals generated when exposed to light when mixed with a photo-free radical generator. Specific examples of the deactivator are shown below.

[0052]

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These deactivators are preferably used in an amount of about 1 to 40 moles per mole of the photo-free radical generator used.

In the case of the negative type, the dye and the photo-free radical generator are contained in the recording layer in a sufficiently separated state until heat is applied during recording. It is preferable for the purpose of keeping the color density of the non-heated portion high.

In the above-mentioned positive type composition, the photo-free radical generator and the dye are preliminarily mixed, and these and the deactivator are separated in a state where the recording layer is sufficiently separated until heat is applied during recording. Is preferably used in order to surely erase the unheated portion during recording.

Although various separation methods are conceivable, typical methods include a method of dispersing in wax, a method of dispersing in a solid, a method of adding to a different layer, and a method of including any of them in microcapsules. .

Among these separation methods, either a dye or a photo-free radical generator is used in a negative system, or a mixture of a dye and a photo-free radical generator or a deactivator is used in a positive system. Preferably, it is included in a capsule. The reason is that preservation before recording is good because sufficient separation from each other can be secured, especially when the dye is placed in the microcapsule, the contact between the external component of the capsule such as a binder and the dye is cut off Because it has good image storability, polyurethane formed by the interfacial polymerization method, by using microcapsules with polyurea as a film material,
This is because it is possible to have sufficient thermal responsiveness that can be used as a thermal recording.

The interfacial polymerization method is described, for example, in "Microcapsules-Their Functions and Applications" (edited by Tamotsu Kondo, Japan Standards Association, 1991), pp. 20-23. Among them, a method in which an oily liquid to be encapsulated and a polyvalent isocyanate are mixed, emulsified and dispersed in water, and then heated is preferable. Various polyvalent isocyanates are known,
Specifically, for example, p-phenylene diisocyanate,
Naphthalene-1,4-diisocyanate, xylylene diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, adduct of hexamethylene diisocyanate and trimethylolpropane, 2,4-
Adducts of tolylene diisocyanate and trimethylolpropane can be mentioned. In the above-mentioned method, the polyvalent isocyanate reacts with water to form a polymer film, but a polyhydric alcohol or a polyamine can be used as a reaction partner. Specific examples of polyhydric alcohols include, for example, ethylene glycol, 1,3-propanediol,
1,4-butanediol, 1,4-cyclohexanedimethanol, 1,2,6-trihydroxyhexane, trimethylolpropane, glycerin, pentaerythritol, 1,4-dihydroxymethylbenzene, 4- (2-
(Hydroxyethoxy) benzenemethanol, 1,4-di (2-hydroxyethoxy) benzene, and the like. Specific examples of the polyvalent amine include, for example, ethylenediamine, trimethylenediamine, hexamethylenediamine, diethylenetetramine, triethylenetetramine and the like.

Regarding the organic solvent used to obtain the oily liquid to be encapsulated, see "Microcapsules-Functions and Applications" (edited by Tamotsu Kondo, Japan Standards Association, 1991).
2) Chapter 2 and “Introduction to the Chemistry of Special Papers” (written by Hiroyuki Moriga,
(Polymer Publishing Association, 1975) The description in Chapter 2 is helpful. In order to prevent evaporation with time, those having a high boiling point of 180 ° C. or higher are preferred. Specifically, alkylated biphenyls such as 4,4'-dimethylbiphenyl and 4-isopropylbiphenyl; alkylated naphthalenes such as isopropylnaphthalene and diisopropylnaphthalene; 1-phenyl-1
Diarylethane such as -xylylethane, 1-phenyl-1-p-ethylphenylethane, diethyl phthalate,
Phthalate esters such as dibutyl phthalate and phosphate esters such as tricresyl phosphate can be mentioned. In addition, low-boiling solvents such as ethyl acetate and butyl acetate may be used.

The heat-sensitive recording layer using the heat-sensitive recording material of the present invention may contain a binder, a pigment and other additives. Hereinafter, the components contained in the heat-sensitive recording layer will be described.

Examples of the binder used in the thermosensitive recording layer according to the present invention include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, alkali or ammonium polyacrylate, and acrylamide. / Acrylic acid ester copolymer, acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, alkali or ammonium salt of styrene / maleic anhydride copolymer, alkali salt of ethylene / maleic anhydride copolymer Or water-soluble polymers such as ammonium salts, polyvinyl acetate, polyurethane, polyacrylate, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer,
Latexes such as methyl acrylate / butadiene copolymer and ethylene / vinyl acetate copolymer are exemplified.

As the pigment, kaolin, calcium carbonate, calcium silicate, magnesium carbonate, barium acid,
Examples include aluminum hydroxide, alumina, urea-formalin resin, polystyrene resin, and vinylidene chloride resin starch.

In addition, waxes such as higher fatty acid metal salts such as zinc stearate, calcium stearate, and barium stearate, paraffin, paraffin oxide, polyethylene, polyethylene oxide, stearic amide, ethylenebisstearic amide, and caster wax. Also, dispersants such as sodium dioctyl sulfosuccinate, sulfonic acid-modified polyvinyl alcohol, benzophenone-based, benzotriazole-based ultraviolet absorbers,
Further, a surfactant, a fluorescent whitening agent and the like may be contained as necessary. In addition, when performing heating recording by laser light, a known infrared absorber such as a phthalocyanine derivative or a nickel complex or another visible light absorber may be contained.

The support used in the present invention includes paper,
Various nonwoven fabrics, woven fabrics, plastic films such as polyethylene terephthalate and polypropylene, polyethylene,
Film-laminated paper, synthetic paper laminated with synthetic resin such as polypropylene and polyethylene terephthalate,
A metal foil such as aluminum, glass or the like, or a composite sheet combining these can be used arbitrarily according to the purpose, but is not limited thereto. These may be opaque, transparent, or translucent. In order to make the background appear white or another specific color, a white pigment, a colored dye, a bubble, a resin, or the like may be contained in the support or on the surface of the support. When the hydrophilicity of the support surface is small and it is difficult to apply the aqueous coating liquid, easy adhesion such as hydrophilic treatment of the support surface by corona discharge, rough surface treatment, or application of various polymers to the support surface is performed. Processing may be performed. In addition, a treatment necessary for straightening curl, preventing static charge, or improving running properties may be performed.

In order to improve the adhesion between the support and the heat-sensitive recording layer, an intermediate layer may be provided.

The heat-sensitive recording material of the present invention may be provided with a protective layer. Examples of the material for the protective layer include polyvinyl alcohol and ammonium alginate. In addition, examples of the material for the protective layer include materials capable of forming a film such as a water-soluble polymer or latex described in the description of the binder for the heat-sensitive recording layer. In this case, a hardener such as a compound having an epoxy group or a zirconium salt or a crosslinking agent may be contained. Alternatively, a protective layer may be formed by applying and curing a light and electron beam curable resin or a thermosetting resin. In any of the above cases, a pigment or the like may be contained in the protective layer in order to further improve the writing and running properties. The average particle size of the pigment used in the protective layer is preferably 2 μm or less, more preferably 0.4 μm or less in terms of image density. Note that the protective layer may be composed of two or three or more layers.

The pigment used as needed in the protective layer has the same composition as that used in the heat-sensitive recording layer. If necessary, various additives described in the description of the heat-sensitive recording layer may be used for the protective layer.

In the heat-sensitive recording layer, another layer, a support or a layer opposite to the surface on which the heat-sensitive recording layer is provided, an electric
It may include a material on which information can be optically and magnetically recorded. Further, a back coat layer can be provided on the surface opposite to the surface on which the heat-sensitive recording layer is provided for the purpose of preventing blocking, curling, preventing static charge, improving running properties, and the like. Necessary information may be printed on the surface on which the thermal recording layer is provided or on the opposite surface.

In each of the above-mentioned layers, it is convenient in many cases to formulate and apply the components as an aqueous dispersion, an aqueous emulsion, or an aqueous solution. For the application of a layer containing a resin or the like, an organic solvent may be used as a medium instead of water. In that case, the resin in the coating liquid may be in a dispersed state or a solution state.

As a coating method, for example, an air knife method,
Curtain coating, roller coating, doctor coating, wire bar coating, slide coating, gravure coating, extrusion coating using a hopper, and the like can be used.

In the recording method of the present invention, first, heat energy is applied imagewise from a heat source, and the light decoloring element or the deactivating element of the present invention is mixed to form a latent image. Examples of the heat source include a heat pump, a heat head, a heat stamp, and a laser beam. Next, an image is formed by irradiating light sufficient to generate free radicals from the photo-free radical generator, and at the same time, fixing is performed. Examples of the light source include a fluorescent lamp, a xenon lamp, and a mercury lamp of various pressures.

[0072]

EXAMPLES Hereinafter, the effects of the present invention will be described in more detail using examples, but the present invention is not limited thereto. In the examples, "parts" and "%" indicate "parts by weight" and "% by weight", respectively.

Example 1 <Preparation of Dye Microcapsule Solution 1> An oil phase solution 1 having the following composition was prepared and mixed / emulsified with 35 parts of a 5% aqueous solution of polyvinyl alcohol (PVA203 manufactured by Kuraray Co., Ltd.). . As an emulsifying device, an ACE homogenizer manufactured by Nippon Seiki Co., Ltd. was used to emulsify by stirring at 12,000 rpm for 3 minutes. The emulsion is immediately heated to 50 ° C.
While maintaining the temperature at 0 ° C., the reaction was carried out for 3 hours while adding stirring to obtain a pigment microcapsule liquid 1. -Oil phase liquid 1- Exemplified Compound D-12 (Dye) 1 part 1-Phenyl-1-xylylethane 15 parts Ethyl acetate 6 parts Xylylenediisocyanate / trimethylolpropane adduct 5 parts

<Preparation of Photoradical Generator Emulsion 1> An oil phase liquid 2 having the following composition was prepared, and sodium dodecylbenzenesulfonate was added to 35 parts of a 5% aqueous solution of polyvinyl alcohol (PVA203 manufactured by Kuraray Co., Ltd.). The mixture was mixed / emulsified with the aqueous phase liquid to which .3 parts were added. As an emulsifying device,
ACE homogenizer manufactured by Nippon Seiki Co., Ltd.
Emulsification was performed by stirring at 00 rpm for 3 minutes to obtain a photo-free radical generator emulsion 1. -Oil phase liquid 2- Exemplified compound PP-1 (photoradical generator) 10 parts 1-Phenyl-1-xylylethane 5 parts Ethyl acetate 3 parts

<Preparation of Thermal Coating Liquid 1> A heat-sensitive coating liquid 1 was prepared with the following composition. Dye microcapsule solution 1 5 parts Photo-free radical generator emulsion 1 7 parts 10% aqueous solution of polyvinyl alcohol (PVA224 manufactured by Kuraray Co., Ltd.) 6 parts Zinc stearate (release agent) 0.8 part

<Preparation of Thermal Recording Sheet 1> Thermal Coating Solution 1
Is applied to a 75 μm thick white polyethylene terephthalate film (hereinafter referred to as a white PET film) so that the reflection density of cyan becomes 1, and dried.
I got

Example 2 Exemplified Compound PP Used as a Photo-Free Radical Generator in Example 1
A thermosensitive recording sheet 2 was obtained in the same manner as in Example 1 except that PP-1 was changed to PP-2.

Example 3 Illustrative compound PP used as a photoradical generator in Example 1
A thermosensitive recording sheet 3 was obtained in the same manner as in Example 1, except that PP-1 was changed to PP-4.

Example 4 Illustrative compound PP used as a photo-radical generator in Example 1
A thermosensitive recording sheet 4 was obtained in the same manner as in Example 1 except that PP-1 was changed to PP-22.

Example 5 <Preparation of Photoradical Radical Generator Emulsion 2> An oil phase liquid 3 having the following composition was prepared, and polyvinyl alcohol (Kuraray Co., Ltd.) was used.
VA203) was mixed with an aqueous phase solution obtained by adding 0.3 parts of sodium dodecylbenzenesulfonate to 35 parts of a 5% aqueous solution /
Emulsification was performed. The emulsification was performed in the same manner as in the preparation of the photo-free radical generator emulsion 1 of Example 1, and the photo-free radical generator emulsion 2 was prepared.
I got -Oil phase liquid 3-Exemplified compound PP-22 (photo free radical generator) 2.5 parts Exemplified compound P-13 (photo free radical generator) 7.5 parts 1-phenyl-1-xylylethane 5 parts Ethyl acetate 3 Department

<Preparation of Thermal Coating Liquid 2> A heat-sensitive coating liquid 2 was prepared with the following composition. Dye microcapsule liquid 1 (obtained in Example 1) 5 parts Photo-free radical generator emulsion 2 7 parts 10% aqueous solution of polyvinyl alcohol (PVA224 manufactured by Kuraray Co., Ltd.) 6 parts Zinc stearate (release agent) 0.8 parts

<Preparation of Thermal Recording Sheet 5> Thermal coating liquid 2
Was applied to a 75 μm-thick white PET film so that the reflection density of cyan became 1, and dried to obtain a heat-sensitive recording sheet 5.

Example 6 The exemplified compound D-12 used as a dye in Example 2 was replaced with D-
7, a thermosensitive recording sheet 6 was obtained in the same manner as in Example 2 except that the reflection density of magenta was applied to 1.

Example 7 Exemplified compound D-12 used as a dye in Example 2 was replaced with D-
A thermosensitive recording sheet 7 was obtained in the same manner as in Example 2 except that the reflection density of yellow was changed to 1 instead of 1.

Example 8 <Preparation of Dye + Photo-free Radical Generator Microcapsule Solution 1>
An oil phase liquid 4 having the following composition was prepared, and mixed / emulsified with 35 parts of a 5% aqueous solution of polyvinyl alcohol (PVA203 manufactured by Kuraray Co., Ltd.). The reaction of emulsification and subsequent microencapsulation by heating was carried out in the same manner as in the preparation of the dye microcapsule 1 of Example 1 to obtain a dye + photoradical generator microcapsule liquid 1. -Oil phase liquid 4- Exemplified compound D-12 (Dye) 1 part Exemplified compound PP-2 (Photoradical generator) 3 parts 1-Phenyl-1-xylylethane 15 parts Ethyl acetate 6 parts Xylylenediisocyanate / trimethylolpropane Addition 5 parts

<Deactivator Dispersion 1> A suspension having the following composition was prepared, filled with 2 mmφ alumina beads, and pulverized with a paint conditioner to obtain a deactivator dispersion 1. -Suspension 1-Exemplified Compound B-3 (Deactivator) 30 parts 1% aqueous solution of sulfonic acid group-modified polyvinyl alcohol 70 parts

<Preparation of Thermosensitive Coating Liquid 3> A thermosensitive coating liquid 3 was prepared with the following composition. Dye + photo-free radical generator microcapsule liquid 1 5 parts Inactivator dispersion liquid 1 3 parts 10% aqueous solution of polyvinyl alcohol (PVA224 manufactured by Kuraray Co., Ltd.) 6 parts Zinc stearate (release agent) 0.8 parts

<Preparation of Thermal Recording Sheet 8> Thermal coating liquid 3
Was applied to a 75 μm-thick white PET film so that the reflection density of cyan became 1, and dried to obtain a heat-sensitive recording sheet 8.

Comparative Example 1 <Preparation of Leuco Dye + Developer Emulsion Liquid 1> An oil phase liquid 5 having the following composition was prepared, and 90 parts of a 3% aqueous solution of polyvinyl alcohol (PVA203 manufactured by Kuraray Co., Ltd.) was added. Mixing / emulsification was performed with an aqueous solution of 0.5 part of sodium sulfonate. The emulsifying apparatus and conditions were the same as in the preparation of the photo-free radical generator emulsion 1 of Example 1 to obtain a leuco dye + developer emulsion 1. -Oil phase liquid 5-Blue 220 (leuco dye) manufactured by Yamada Chemical Industry Co., Ltd. 2 parts Exemplified compound A (Developer 1) 2 parts Exemplified compound B (Developer 2) 1 part Exemplified compound C (Developer 3) 8 parts diethyl maleate 5 parts ethyl acetate 10 parts

<Preparation of Decolorant Microcapsule Solution 1> An oil phase solution 6 having the following composition was prepared and mixed / emulsified with 80 parts of a 3% aqueous solution of polyvinyl alcohol (PVA203 manufactured by Kuraray Co., Ltd.). Emulsifying equipment and conditions, reaction conditions,
A decolorizing agent microcapsule liquid 1 was obtained in the same manner as in the preparation of the dye microcapsule liquid 1 of Example 1. -Oil phase liquid 6-Exemplified compound D (decoloring agent) 10 parts 1-phenyl-1-xylylethane 20 parts Ethyl acetate 10 parts Xylylene diisocyanate / trimethylolpropane adduct 25.2 parts

<Preparation of Thermosensitive Coating Solution 4> A thermosensitive coating solution 4 was prepared with the following composition. Leuco dye + developer emulsion 1 20 parts Decolorizer microcapsule liquid 1 20 parts 10% aqueous solution of polyvinyl alcohol (PVA224 manufactured by Kuraray Co., Ltd.) 30 parts Zinc stearate (release agent) 0.8 part

<Preparation of Thermal Recording Sheet 9> Thermal coating liquid 4
Was applied to a 75-μm-thick white PET film so that the reflection density of cyan became 1, and dried to obtain a heat-sensitive recording sheet 9.

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Comparative Example 2 <Preparation of Microcapsule Solution 1 of Organic Boron Compound Anion Salt of Organic Cationic Dye> An oil phase solution 7 having the following composition was prepared, and polyvinyl alcohol (PVA20 manufactured by Kuraray Co., Ltd.) was prepared.
It was mixed / emulsified with 45 parts of the 3% aqueous solution of 3). The emulsifying apparatus, conditions, and reaction conditions were the same as in the preparation of the dye microcapsule liquid 1 of Example 1, and an organic boron compound anion salt microcapsule liquid 1 of an organic cationic dye was obtained. —Oil phase liquid 7— Exemplified compound E (organic boron compound anion salt of an organic cationic dye) 0.41 part Triethylammonium tetrabutyl borate 0.08 part Methyl isobutyl ketone 12 parts Tricresyl phosphate 15 parts Xylylene diisocyanate / Trimethylolpropane adduct 12 parts

<Cyanine Dye Inactivator Dispersion 1> A suspension 2 having the following composition was prepared, filled with 2 mmφ alumina beads, and pulverized with a paint conditioner. I got -Suspension 2-benzyl 4-hydroxybenzoate (deactivator) 30 parts 1% aqueous solution of sulfonic acid group-modified polyvinyl alcohol 150 parts

<Preparation of heat-sensitive coating liquid 5> A heat-sensitive coating liquid 5 was prepared with the following composition. Organic cationic dye Organic boron compound anion salt microcapsule liquid 1 9 parts Cyanine dye quencher dispersion liquid 1 9 parts 10% aqueous solution of polyvinyl alcohol (PVA224 manufactured by Kuraray Co., Ltd.) 4 parts Zinc stearate (release agent) 0 .8 copies

<Preparation of Thermal Recording Sheet 10> Thermal coating liquid 1 was applied to a 75 μm thick white PET film so that the reflection density of magenta became 1, and dried to obtain thermal recording sheet 10.

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Comparative Example 3 Exemplified Compound PP Used as a Photo-Free Radical Generator in Example 1
A thermosensitive recording sheet 11 was obtained in the same manner as in Example 1, except that -1 was changed to P-5. << Evaluation of sample >><Evaluationmethod> 1) Evaluation of thermal printing
The measurement was performed using TH-PMD manufactured by Okura Electric. Change the applied temperature from 100 ° C to 190 ° C in steps of 10 ° C,
Printing was performed at f / cm ² for 5 seconds.

2) Light Irradiation The samples of Examples 1 to 8 and Comparative Example 3 of the present invention were irradiated with ultraviolet light, and the sample of Comparative Example 1 was irradiated with ultraviolet light and white light except for a part of the evaluation of the fixing property. Instead, the sample of Comparative Example 2 was irradiated with white light.

Irradiation with Ultraviolet Light Irradiation with ultraviolet light was performed using a high-pressure mercury lamp until the density of the decolored portion became stable. The sample surface was cooled with cold air during irradiation to avoid the effect of heating the sample surface.

White light irradiation White light irradiation was performed using a white fluorescent lamp until the density of the decolored portion became stable. To avoid the effects of heating the sample surface,
During the irradiation, the sample surface was cooled by cold air.

3) Evaluation of fixability The non-heated portion of the sample which had been subjected to thermal printing according to 1) and irradiated with ultraviolet light or white light according to 2) was again subjected to thermal printing, ultraviolet light or white light irradiation in the same manner. The reflection density of the heat-printed portion of this sample was measured and compared with the density after the first heat-printing and irradiation with ultraviolet light or white light, to determine a fixing property.

4) Evaluation of Raw Preservation The sample before printing was left in a dark place at 60 ° C. and 80 RH% for 48 hours to perform a heating treatment. Thereafter, density gradation printing and ultraviolet or white light irradiation are performed in which the applied energy is changed stepwise, and the reflection density of the portion where the reflection density is maximum is measured using a Macbeth RD-918 reflection density measuring device. By comparing the measured values with those obtained by performing the same operation on a sample that had not been subjected to the heating treatment, evaluation was made of the maximum density of underground fading.

5) Evaluation of image storability A sample that had been subjected to density gradation printing in which the applied energy was changed in a stepwise manner and irradiation with ultraviolet light or white light was heated at 60 ° C.
It was left in a dark place under the condition of RH% for 48 hours to perform a heating treatment. Thereafter, the measurement of the reflection density of the portion where the reflection density was the maximum was performed using a Macbeth RD-918 reflection density measurement device, and the change with respect to the measurement value of the same portion before the heat treatment was compared.

6) Evaluation of light fastness A sample that had been subjected to density gradation printing and ultraviolet or white light irradiation in which the applied energy was changed stepwise was exposed to a xenon lamp for 3 days, and the same portion before the xenon exposure treatment was applied. And changes in color tone were compared.

7) Evaluation of handleability in room light The sample before printing was left under room light for 30 minutes, and the sample subjected to density gradation printing in which the applied energy was changed stepwise and irradiation of ultraviolet light or white light was used. The reflection density of the portion where the reflection density was maximized was measured using a Macbeth RD-918 reflection density measurement device, and the change with the density of the sample that had not been subjected to the indoor light exposure treatment was compared.

<Evaluation Results>

<Evaluation Results of Decoloring Property or Color Forming Property> Samples that had been subjected to density gradation printing and stepwise irradiation with ultraviolet light or white light in which the applied energy was changed were evaluated for decoloring property or color forming property. The results are shown in Table 1 below.

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[Table 1]

<Evaluation Results of Fixing Property> In Examples 1 to 8 and Comparative Examples 2 and 3, there was no significant difference in density. Comparative Example 1
Then, decolorization was seen. Evaluation was performed after UV irradiation was performed on Comparative Example 1, but the same results were obtained.

<Evaluation results of raw storability and image storability> Both raw storability and image storability showed good results in Examples 1 to 8, and Comparative Examples 1 and 2 showed a decrease in the maximum density. In Comparative Example 3, an increase in the minimum density was observed in the evaluation of image storability.

<Evaluation Results of Light Fastness> No significant difference was observed in Examples 1 to 8 and Comparative Example 3, and the non-printed portion was colored brown in Comparative Example 1 and the maximum density was decreased in Comparative Example 2. Was done.

<Evaluation Results of Handleability in Room Light> In Examples 1 to 8 and Comparative Examples 1 and 3, there was no significant difference in the concentration. In Comparative Example 2, a decrease in density was observed by exposure to room light, and a further decrease in density was observed when thermal printing and white light irradiation were performed.

From the above evaluation results, according to the present invention, Table 1
From this, it can be seen that sufficient coloring and decoloring can be obtained. Also, it can be seen that sufficient raw storability, image storability (including improvement in color reproducibility), light resistance, and fixability can be similarly obtained. In addition, the handleability in a bright room is good.
From these results, it can be seen that according to the present invention, a thermosensitive recording sheet of excellent quality can be obtained.

[0116]

According to the recording material and recording method of the present invention,
There is no problem such as background fogging or image density reduction due to poor storage stability before recording, and a stable image can be obtained after recording.
Further, according to the recording material and the recording method of the present invention, fixing is possible, there is no recoloring, and handling in a bright room becomes possible.

Claims (1)

[Claims] 1. A photo-decolorizable element comprising a photo-free radical generator that absorbs light to generate free radicals and a dye that is decolorized by the free radicals generated by the photo-free radical generator on a support. A recording material provided on the same surface, comprising at least one acylphosphor oxide derivative represented by the following general formula 1 or 2 as the photo-free radical generator. Embedded image (Wherein R ^{1 to} R ⁶ represent a substituted or unsubstituted saturated or unsaturated alkyl group, alkoxy group, aryl group, amino group, heterocyclic group or halogen atom, which may be the same or different from each other. R ² and R ³ may be linked to each other to form a ring.)