JPH0768937A - Reversible recording material - Google Patents

Abstract

(57) [Summary] [Object] To improve the stability of a recorded image in a reversible recording material in which a recorded image recorded by light or heat is erased by heat or light. A reversible recording material containing a recording material in which a recording image recorded by light or heat is erased by heat or light is contained in a support or in a recording layer provided on the support. The reversible recording material is characterized in that one or both surfaces of the recording material are provided with a protective layer containing a UV absorber which is liquid at room temperature and containing microcapsules having substantially no coloring ability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible recording material in which a recorded image recorded by light or heat is erased by heat or light.

[0002]

2. Description of the Related Art In recent years, reversible thermosensitive recording materials which can be repeatedly recorded or erased by heat have been actively developed. As a conventional reversible heat-sensitive recording material, JP-A-55-1
In Japanese Patent No. 5419, a physical change in which a cloudy state and a transparent state are reversibly repeated depending on a difference in heating temperature and one of the states is stably maintained at a specific temperature or lower (organic low molecule JP-A-2-188294 discloses a mixed system of a leuco dye and a color-developing / reducing agent, which usually has a hydroxyl group and a carboxyl group in the molecule as a color-reducing / reducing agent and reversibly releases hydrogen ions. There is described a substance (leuco dye type) which utilizes a chemical change capable of developing a color at a high temperature and decoloring at a temperature lower than that, using an organic substance having a property of being released into the atmosphere.

Since the method of recording and erasing by using the amount of change in thermal energy and the change in cooling rate as described above requires delicate temperature control, a reversible recording medium of a more easily handled type is demanded. Therefore, the present inventors
Although a reversible recording material using 3,4-tetrakis (benzylthio) benzene was developed, a drawback that color change due to light is likely to occur over time was recognized.

[0004]

An object of the present invention is to provide a reversible recording material in which a recorded image recorded by light or heat is erased by heat or light and the stability of the recorded image is increased. is there.

[0005]

According to the present invention, a recording material in which a recorded image recorded by light or heat is erased by heat or light is contained in a support or a recording layer provided on the support. In the reversible recording material, one or both sides of the reversible recording material are provided with a protective layer containing a UV absorber which is liquid at room temperature and containing microcapsules having substantially no coloring ability. Is a reversible recording material.

[0006]

The reversible recording material of the present invention is a recording material in which a recorded image recorded by light or heat is erased by heat or light, such as 1,2,3,4-tetrakis (benzylthio) benzene or 2 , 2 ', 5,5'-tetramethyldistibolyl is used, but is not limited thereto. The former compound is colored from colorless to dark pink when irradiated with ultraviolet light, and when heated to 80 to 120 ° C., it returns to a colorless state again. When this specific compound is used as a reversible recording material, the specific compound may be contained in a support such as a film, or the compound may be sandwiched between two films, or a film or paper, etc. The compound may be contained in the recording layer provided on the support.

For example, a recording material containing this specific compound is entirely irradiated with ultraviolet light to be colored, and then a positive or negative recorded image is obtained by thermal energy from a thermal head or the like. After recording, irradiating the entire surface with ultraviolet light again,
The entire surface is colored and the recorded image is erased.

When a recording layer containing a reversible recording material is formed on a support, the specific compound is contained in an amount of 5 to 95% by weight, preferably 40 to 90% by weight, based on the total solid content of the recording layer. It is desirable to adjust the degree. Further, by providing a protective layer on the recording layer, a clear recorded image can be obtained even if it is repeatedly used.

For use as a reversible recording material, the average particle size is preferably 2 μm or less, more preferably 1 μm or less. As a method for forming fine particles of this specific compound, there are a method of precipitating fine crystals using a suitable poor solvent during synthesis, or a method of using a pulverizer such as a ball mill, attritor, or sand mill with water as a dispersion medium.

In the coating solution for forming the recording layer, starch such as oxidized starch, etherified starch, dialdehyde starch and esterified starch, cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose and carboxymethyl cellulose, gelatin, etc. are usually used as binders. Casein, gum arabic, fully or partially saponified polyvinyl alcohol, polyvinyl alcohol modified with various functional groups, specifically acetoacetyl modified polyvinyl alcohol, carboxyl modified polyvinyl alcohol, sulfonic acid modified polyvinyl alcohol, olefin modified polyvinyl Alcohol, nitrile modified polyvinyl alcohol,
Amido-modified polyvinyl alcohol, polyvinyl alcohol such as pyrrolidone-modified polyvinyl alcohol and modified polyvinyl alcohol containing silicon atom, diisobutylene
Maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, natural rubber emulsion,
Styrene / butadiene copolymer emulsion, acrylonitrile / butadiene copolymer emulsion, methyl methacrylate / butadiene copolymer emulsion, polychloroprene emulsion, vinyl acetate emulsion,
At least one kind of ethylene / vinyl acetate emulsion or the like is added in an amount of 5 to 95% by weight, preferably 15 to 30% by weight, based on the total solid content of the recording layer.

Various kinds of auxiliaries can be further added to the coating solution, for example, sodium dioctyl sulfosuccinate, sodium dodecylbenzene sulfonate, sodium lauryl alcohol sulfate / sodium, fatty acid metal salt dispersant, stearic acid. Wax such as zinc, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, defoaming agent,
Fluorescent dyes, coloring dyes, etc. are appropriately added.

Further, kaolin, clay,
Inorganic pigments such as talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, particulate anhydrous silica, activated clay, styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, and raw starch particles are added. You can also do it.

As the support of the reversible recording material of the present invention, opaque, semi-transparent or transparent materials such as high quality paper, glassine paper, plastic film and synthetic paper are used.
The coating method of the recording layer is not particularly limited,
It can be formed according to well-known and conventional techniques,
For example bar coating, air knife coating,
It is formed by a method of applying and drying a coating liquid by rod blade coating, pure blade coating, short dwell coating, or the like. When a plastic film is used as the support, the coating efficiency can be increased by subjecting the surface to treatments such as corona discharge and electron beam irradiation. The coating amount of the coating liquid is also not particularly limited, but is usually 0.5 to 12 g / m ² and preferably 1 to 10 g / m ² in terms of dry weight.
The range is about ² .

In the reversible recording material of the present invention, a protective layer is provided on the recording layer or on the back surface of the transparent support, which contains a UV absorber which is liquid at room temperature and contains microcapsules having substantially no color-forming ability. By providing, it is possible to obtain a recording image which is difficult to be erased with time even when exposed to sunlight or light of a fluorescent lamp.

Since the ultraviolet absorber used in the present invention is liquid at room temperature, it is not necessary to dissolve the ultraviolet absorber in an organic solvent when synthesizing oil-in-water type microcapsules. It can be contained in a concentration, and the ultraviolet absorbing ability is remarkably improved.

The UV absorber used in the present invention is not particularly limited as long as it is a liquid UV absorber at room temperature, but a benzotriazole derivative is particularly preferable. Specific examples thereof include the following. . 2- (2 '
-Hydroxy-3'-dodecyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-
3'-undecyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3'-tridecyl-5'-methylphenyl) benzotriazole, 2-
(2'-Hydroxy-3'-tetradecyl-5'-methylphenyl) benzotriazole, 2- [2'-hydroxy-4 '-(2 "-ethylhexyl) oxyphenyl] benzotriazole, 2- [2'-hydroxy −
4 '-(2 "-ethylheptyl) oxyphenyl] benzotriazole, 2- [2'-hydroxy-4'-
(2 ″ -Ethyloctyl) oxyphenyl] benzotriazole, 2- [2′-hydroxy-4 ′-(2 ″ -propyloctyl) oxyphenyl] benzotriazole, 2- [2′-hydroxy-4 ′-(2 ″ -Propylheptyl) oxyphenyl] benzotriazole, 2-
[2'-hydroxy-4 '-(2 "-propylhexyl) oxyphenyl] benzotriazole, 2- [2'
-Hydroxy-4 '-(1 "-ethylhexyl) oxyphenyl] benzotriazole, 2- [2'-hydroxy-4'-(1" -ethylheptyl) oxyphenyl]
Benzotriazole, 2- [2'-hydroxy-4'-
(1 ″ -Ethyloctyl) oxyphenyl] benzotriazole, 2- [2′-hydroxy-4 ′-(1 ″ -propyloctyl) oxyphenyl] benzotriazole, 2- [2′-hydroxy-4 ′-(1 ″ -Propylheptyl) oxyphenyl] benzotriazole, 2-
[2'-hydroxy-4 '-(1 "-propylhexyl) oxyphenyl] benzotriazole, methyl-3
-[3-tert-Butyl-5- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] propionate and polyethylene glycol (molecular weight about 300)
Condensate with etc. Among these, preferred are 2- (2'-hydroxy-3'-dodecyl-5'-methylphenyl) benzotriazole and 2- [2'-hydroxy-4'-.
(2 "-ethylhexyl) oxyphenyl] benzotriazole, methyl-3- [3-tert-butyl-5-
It is a condensate of (2H-benzotriazol-2-yl) -4-hydroxyphenyl] propionate and polyethylene glycol (molecular weight about 300).

Regarding the amount of the ultraviolet absorber used,
It is preferably present in the protective layer in the range of 0.1 to 3.0 g / m ² , and more preferably 0.2 to 2.0 g / m ^2.
Is the range. If the amount of the ultraviolet absorber encapsulated in the microcapsules in the protective layer is less than 0.1 g / m ² , the effect of preventing yellowing of the background portion of the heat-sensitive recording material decreases. Further, if it exceeds 3.0 g / m ² , the protective layer inevitably becomes thick, and the recording sensitivity is lowered. Further, the ultraviolet absorber is preferably 10% by weight or more with respect to the microcapsule core substance formed of a mixed solution of the ultraviolet absorber and, if necessary, an organic solvent. That is, the organic solvent content of the microcapsule core material is preferably less than 90% by weight, more preferably 2%.
It is in the range of about 0 to 70% by weight.

Incidentally, if the ultraviolet absorber is less than 10% by weight with respect to the microcapsule core substance, in order to exert the effect of preventing yellowing of the background portion of the thermosensitive recording medium, the microcapsule coating amount should be increased. Since this is necessary, the protective layer inevitably becomes thick and the recording sensitivity decreases.

Further, it is possible to use an ultraviolet absorber which is solid at room temperature in combination within the range that does not impair the effects of the present invention. Specific examples of the ultraviolet absorber that is solid at room temperature include the following. Phenyl salicylate, p
Salicylic acid-based UV absorbers such as -tert-butylphenyl salicylate and p-octylphenyl salicylate, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-
4-octyloxybenzophenone, 2-hydroxy-
4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-
Benzophenone-based UV absorbers such as hydroxy-4-methoxy-5-sulfobenzophenone, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole,
2- (2'-hydroxy-5'-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-
3 ', 5'-di-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-tert
-Butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-
Di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-amylphenyl) benzotriazole, 2
-[2'-hydroxy-3 '-(3 ", 4", 5 ",
6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl] benzotriazole, 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, 2- [2′-hydroxy-3 ′, 5′- Benzotriazole-based UV absorbers such as bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2-ethylhexyl-2-cyano-3,3'-diphenylacrylate, ethyl-2-cyano-3,3 ′-
There are cyanoacrylate-based UV absorbers such as diphenyl acrylate and hindered amine-based UV absorbers. These ultraviolet absorbers can be used in combination of two or more, and benzotriazole derivatives are preferable from the viewpoint of the effect.

The microcapsules containing the ultraviolet absorber used in the present invention can be prepared by various known methods. Generally, a mixed solution of the ultraviolet absorber and, if necessary, an organic solvent is used as a core substance. It is prepared by a method of emulsifying and dispersing in an aqueous medium and forming a polymer wall film around it. Wall membrane materials include polyurethane, polyurea, polyurethane / polyurea, polyester,
Examples thereof include polycarbonate, aminoaldehyde resin, melamine resin, polystyrene, styrene-methacrylate copolymer, styrene-acrylate copolymer, gelatin, polyvinyl alcohol and the like.

In the present invention, since the microcapsules are added to the protective layer, the use of polyurethane / polyurea resin having excellent heat resistance as the wall film substance also has the effect of preventing sticking with the thermal head during recording. To be In addition, the inorganic pigment added to the protective layer for the purpose of improving printability and sticking reduces the recording density due to whitening of the recorded image when the addition ratio is high. Since the capsule has a lower refractive index than the inorganic pigment and has a spherical shape, the whitening of the recorded image due to irregular reflection of light in the protective layer is small.

The polyurethane / polyurea wall film is prepared by mixing a polyol that reacts with a polyvalent isocyanate or an adduct of a polyvalent isocyanate and a polyol with a core substance to be encapsulated to dissolve a protective colloid substance such as polyvinyl alcohol. It is produced by emulsifying and dispersing in the above aqueous medium, raising the liquid temperature, and causing a polymer forming reaction at the oil drop interface.

Examples of the polyvalent isocyanate compound 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'-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, Diisocyanates such as 4-diisocyanate, 4,4 ′, 4 ″ -triphenylmethane triisocyanate, triisocyanates such as toluene-2,4,6-triisocyanate, 4,4′-dimethyldiphenylmethane-2,2 ′ , 5,5'-Tetraisocyanate and other tetraisocyanates, addition product of hexamethylene diisocyanate and trimethylolpropane, addition of 2,4-tolylene diisocyanate and trimethylolpropane , An adduct of xylylene diisocyanate and trimethylolpropane, an isocyanate prepolymer of an adduct of tolylene diisocyanate and hexane triol.

As the polyol compound, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8 -Octanediol, propylene glycol, 2,3-dihydroxybutane, 1,2-dihydroxybutane, 1,3
-Dihydroxybutane, 2,2-dimethyl-1,3-propanediol, 2,4-pentanediol, 2,5-
Hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, dihydroxycyclohexane, diethylene glycol, 1,2,
Aliphatic polyols such as 6-trihydroxyhexane, phenylethylene glycol, 1,1,1-trimethylolpropane, hexanetriol, pentaerythritol, glycerin, 1,4-di (2-hydroxyethoxy) benzene, resorcinol dihydroxyethyl ether. Examples thereof include condensation products of aromatic polyhydric alcohols such as alkylene oxide and p-xylylene glycol, m-xylylene glycol, α, α′-dihydroxy-p-diisopropylbenzene, 4,4′- Dihydroxydiphenylmethane, 2- (p, p'-dihydroxydiphenylmethyl) benzyl alcohol, 4,4 '
-Isopropylidene diphenol, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide, ethylene oxide adduct of 4,4'-isopropylidenediphenol, propylene of 4,4'-isopropylidenediphenol A polyol compound such as an oxide adduct can be used, and various auxiliary agents such as a reaction accelerator can also be used in combination.
Of course, the polyvalent isocyanate compound and the polyol compound are not limited to those described above, and two or more kinds may be used in combination.

The polyurethane / polyurea wall film material used in the present invention is preferably one having three or more isocyanate groups in the molecule of a polyvalent isocyanate compound or an adduct of a polyvalent isocyanate compound and a polyol.

In the microcapsules used in the present invention, a high-boiling point hydrophobic medium can be generally included with an ultraviolet absorber. Specific examples of the high boiling point hydrophobic medium preferably used in the present invention include, for example, tricresyl phosphate, phosphate esters such as octyldiphenyl phosphate, dibutyl phthalate, and phthalate esters such as dioctyl phthalate.
Carboxylic acid esters such as butyl oleate, various fatty acid amides, alkylated naphthalenes such as diethylene glycol dibenzoate, monoisopropyl naphthalene and diisopropyl naphthalene, alkylated biphenyls such as isopropyl biphenyl, xenoxy alkanes such as o-phenylphenol glycidyl ether, tris Examples thereof include acrylic acid esters such as methylolpropane triacrylate, esters of polyhydric alcohols and unsaturated carboxylic acids, chlorinated paraffins, 1-phenyl-1-methyl-1-xylermethane and the like. Of course, these may be used in combination of two or more kinds. At the time of emulsification, the lower the viscosity of the hydrophobic medium, the smaller the emulsified particle size and the narrower the particle size distribution. Therefore, a low boiling point solvent can be added if necessary. Specific examples of the low boiling point solvent include ethyl acetate, butyl acetate, methylene chloride and the like. Of course, it is not limited to these and two or more kinds may be used in combination.

When the wrap film is wound around the protective layer surface of the recording material of the present invention, when the wall film material is small, the core substance in the microcapsules is extracted by the action of the plasticizer added to the wrap film to cause background fog and the like. Since the microcapsule core material and the microcapsule wall membrane material may be mixed with 35 microcapsule wall membrane material,
To 95% by weight, more preferably 40 to
It is 80% by weight. If the wall film material of the microcapsules exceeds 80% by weight, it becomes difficult to emulsify the fine particles.

Examples of emulsifiers used in the production of microcapsules include various anions, nonions, cations, amphoteric water-soluble polymers and surfactants. The amount of the emulsifier used is not particularly limited, but generally the wall film is
In the case of polyurethane / polyurea resin, the amount may be adjusted to 1 to 50% by weight, more preferably 3 to 30% by weight, based on the microcapsule wall film agent and the core substance.

The average particle size of the microcapsules used in the present invention is preferably adjusted in the range of 0.1 to 3 μm in consideration of the ultraviolet absorption efficiency, the image quality of the recorded image and the like. Further, the microcapsule dispersion is contained at least in the protective layer, but it may be added in the heat-sensitive recording layer. The content of the microcapsules in the protective layer is 5 to 80% by weight of the total solid content of the protective layer, more preferably 20 to
It is desirable to adjust in the range of about 70% by weight.

Various water-soluble resins are used for the protective layer,
Examples of such water-soluble resin include methyl cellulose,
Cellulose derivatives such as ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, starches such as casein, arabic gum, oxidized starch, etherified starch, dialdehyde starch, esterified starch, fully saponified or partially saponified polyvinyl alcohol, and various functional groups. Modified polyvinyl alcohol, specifically acetoacetyl modified polyvinyl alcohol, carboxyl modified polyvinyl alcohol, sulfonic acid modified polyvinyl alcohol, olefin modified polyvinyl alcohol, nitrile modified polyvinyl alcohol, amide modified polyvinyl alcohol, pyrrolidone modified polyvinyl alcohol or silicon atom. Denatured polyvinyl alcohol containing or with polyvinyl alcohol (acrylamide, vinylpyrrolidone, acrylonitrile Graft polymer and the like of the copolymer of the like).

Further, in order to further enhance water resistance and plasticizer resistance of the protective layer, a curing agent may be added to the coating liquid for forming the protective layer. Examples of the curing agent include glyoxal, methylolmelamine, potassium persulfate, ammonium persulfate, sodium persulfate, ferric chloride, magnesium chloride, boric acid, alum, ammonium chloride and the like.

Further, a pigment may be added to the protective layer, if necessary, in order to further improve printability and sticking. Specific examples thereof include calcium carbonate, zinc oxide, aluminum oxide, Inorganic pigments such as titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc, kaolin, clay, calcined kaolin, colloidal silica, styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, raw starch Examples include organic pigments such as particles. It is generally desirable to adjust the amount used in the range of about 5 to 500 parts by weight with respect to 100 parts by weight of the resin component.

Further, in the coating liquid, if necessary, a lubricant such as zinc stearate, calcium stearate, stearic acid amide, polyethylene wax, carnauba wax, paraffin wax, ester wax, sodium dioctylsulfosuccinate, and dodecylbenzenesulfone. Sodium acid, surfactant such as sodium lauryl alcohol sulfate / sodium salt, alginate, fatty acid metal salt, etc., UV absorbers such as benzophenone type, triazole type, antifoaming agent, fluorescent dye, coloring dye, etc. It can also be added as appropriate.

The coating liquid for the protective layer is generally prepared as an aqueous coating liquid, and if necessary, sufficiently mixed and dispersed by a mixing / stirring machine such as a mixer, an attritor, a ball mill or a roll mill, and then various known coatings. It is applied and dried on the recording layer by a device. After application, it can be dried by irradiation with ultraviolet rays or electron beams. The coating amount of the coating liquid is not particularly limited, but if it is less than 0.1 g / m ² , the desired effect of the present invention cannot be sufficiently obtained, and 10
If it exceeds g / m ² , the recording sensitivity of the reversible recording material may be significantly lowered.
10 g / m ² approximately, it is preferably adjusted in the range of about 0.5 to 5 g / m ^2.

If necessary, after the recording layer is coated or the protective layer is coated, a super calendering treatment may be performed to further improve the image quality and the image density. Further, in order to provide an undercoat layer composed of an adhesive and a white pigment, and to provide a recording layer and a protective layer on this to enhance recording density, sensitivity, storability, and to eliminate the influence of oil and plasticizer from the back surface, A back barrier layer composed of an adhesive and a white pigment may be provided on the back surface of the recording material to further improve the storage stability. As the adhesive or the white pigment used for the undercoat layer or the back barrier layer, those used for the recording layer can be appropriately used. Further, various well-known techniques in the field of heat-sensitive recording material production can be added as necessary, for example, by treating the back surface of the recording material with an adhesive to process it into an adhesive label.

[0036]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Unless otherwise specified, "part" and "%" in the examples mean "part by weight" and "% by weight", respectively.

Example A Preparation of Liquid A A composition consisting of 100 parts of 1,2,3,4-tetrakis (benzylthio) benzene, 20 parts of a 5% aqueous solution of methylcellulose, and 160 parts of water was used to obtain an average particle size of 0. It was pulverized to 8 μm to obtain a liquid A.

Formation of Recording Layer 280 parts of solution A, 10% of silicon-modified polyvinyl alcohol
A coating solution obtained by mixing and stirring 100 parts of the aqueous solution was applied to 80 g / m ² of synthetic paper [trade name: YUPO, manufactured by Oji Yuka Co., Ltd.] so that the coating amount after drying was 4 g / m ² and dried. A recording layer was formed.

Preparation of Solution B In an agitating and mixing container equipped with a heating device, 60 parts of an 8% aqueous solution of polyvinyl alcohol (trade name: PVA-217, manufactured by Kuraray Co., Ltd.) was added to prepare an aqueous medium for producing microcapsules. Separately, 3 parts of ethyl acetate, 12 parts of 2- (2'-hydroxy-3'-dodecyl-5'-methylphenyl) benzotriazole, a (3: 1) adduct of xylylene diisocyanate and trimethylolpropane [trade name: Takenate D-110N, manufactured by Takeda Pharmaceutical Co., Ltd., containing 25% by weight of ethyl acetate] 18 parts of a solution as a core material and a wall film material of the capsule in the above-mentioned aqueous medium for capsule production.
Using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), the emulsion was dispersed while cooling until the average particle diameter became 2 μm. 50 parts of water was added to this emulsified dispersion and reacted at 60 ° C. for 3 hours with stirring to prepare microcapsules of a polyurethane / polyurea wall film containing an ultraviolet absorber.

Formation of protective layer Liquid B 220 parts, acetoacetyl group-modified polyvinyl alcohol 10% aqueous solution 150 parts, kaolin [trade name: UW
-90, manufactured by EMC] 15 parts, zinc stearate 30
% Dispersion liquid and 30 parts of water were mixed and stirred to obtain a coating solution for the protective layer, which had a coating amount of 6 g on the recording layer after drying.
/ M ² was applied and dried, and calendered to obtain a reversible recording material.

Comparative Example A reversible recording material was obtained in the same manner as in Example except that the protective layer was not used.

When the recording surfaces of the above two kinds of reversible recording materials thus obtained were irradiated with a xenon lamp, the entire surface became dark pink. Place this on a hot plate at 120 ° C for 15 seconds at 0.5K
When pressed at a pressure of g / cm ² , the heated portion was erased and turned white. When these were exposed to a fluorescent lamp (5000 lux) for one week, the recorded portion was colored dark pink in the comparative example, but the example was clearly readable. Irradiation of the example with a xenon lamp produced a dark pink color. This xenon lamp irradiation and heating were repeated 15 times, and the reaction from dark pink to decoloring and from decoloring to dark pink was reproducibly repeated.

[0043]

As is apparent from the examples, the recording material of the present invention is a reversible recording material having excellent reproducibility of recorded images and increased stability of recorded images.

Claims (1)

[Claims] 1. A reversible recording material comprising a recording material, in which a recording image recorded by light or heat is erased by heat or light, contained in a support or in a recording layer provided on the support. A reversible recording material comprising a reversible recording material, on one or both sides of which a protective layer containing a UV absorber which is liquid at room temperature and containing microcapsules having substantially no coloring ability is provided.