JPH06340174A - Reversible heat-sensitive recording material - Google Patents

Abstract

PURPOSE:To provide a reversible heat-sensivie recording material which is capable of performing formation and erasure of an image in a favorable contrast and holding of the image stable with age under circumstances of daily life and superior in sensitivity and repeating durability. CONSTITUTION:In a reversible heat-sensitive recording material containing a dye precursor, which is ordinarily colorless or light-colored, and a reversible developer, which allows the dye precursor to generate a reversible color tone change by a difference in cooling rates after heating, an undercoat layer containing hollow particles is provided between a substrate and reversible heat- sensitive layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible thermosensitive recording material capable of forming and erasing an image by controlling thermal energy.

[0002]

2. Description of the Related Art A heat-sensitive recording material generally comprises a support and a heat-sensitive recording layer containing an electron-donating, usually colorless or light-colored dye precursor and an electron-accepting developer as main components. By heating with a thermal head, a heating pen, a laser beam or the like, a dye precursor and a developer react instantaneously to obtain a recorded image. JP-B-43-4160 and JP-B-45-
No. 14039 is disclosed.

In general, such a heat-sensitive recording material cannot erase the portion of the image once formed and return to the state before the image is formed. Therefore, when further information is recorded, the image is not recorded. There was no choice but to add to the formation part. Therefore, when the area of the heat-sensitive recording portion is limited, there is a problem that the recordable information is limited and it is impossible to record all the necessary information.

In recent years, reversible thermosensitive recording materials capable of repeating image formation and image erasing have been devised in order to deal with such a problem, for example, JP-A-54-119377 and JP-A-63-63. 39377, JP-A-63-4
Japanese Patent No. 1186 describes a heat-sensitive recording material composed of a resin base material and organic low-molecules dispersed in the resin base material. However, since this method reversibly changes the transparency of the heat-sensitive recording material by heat energy, the contrast between the image-formed area and the image-unformed area is insufficient. Also, the sensitivity was insufficient.

Further, in the methods described in JP-A-50-81157 and JP-A-50-105555, since the image to be formed changes according to the ambient temperature, the image forming state and the erasing state. The holding temperatures are different, and these two states cannot be held for an arbitrary period at room temperature.

Further, in Japanese Patent Laid-Open No. 59-120492, the hysteresis characteristic of the color-developing component is utilized to keep the recording material in the hysteresis temperature range, thereby forming an image.
Although a method of maintaining the erased state is described, this method requires a heating source and a cooling source for image formation and erasure, and the temperature range in which the image formation state and the erased state can be maintained is limited to the hysteresis temperature region. However, it is still insufficient for use in the temperature environment of daily life.

On the other hand, JP-A-2-188293, JP-A-2-188294, and International Publication No. WO90 /
No. 11898 describes a reversible heat-sensitive recording material composed of a leuco dye and a color-developing and decoloring agent for coloring and decoloring the leuco dye by heating. The color-developing / reducing agent is an amphoteric compound having an acidic group for coloring a leuco dye and a basic group for decoloring a leuco dye that has formed a color, and a coloring action by an acidic group or a decoloring action by a basic group by controlling thermal energy. One of them is preferentially generated, and coloring and erasing are performed. However, in this method, it is impossible to completely switch the color development reaction and the color removal reaction only by controlling the thermal energy, and since both reactions occur at a certain ratio at the same time, sufficient color development density cannot be obtained, and the color removal Can not be done completely. Therefore, sufficient image contrast cannot be obtained. Also,
Since the decoloring action of the basic group also acts on the color development part at room temperature,
The phenomenon that the density of the color-developed portion decreases with time cannot be avoided.

As described above, according to the conventional technique, there is a reversible thermosensitive recording material having a good image contrast, capable of forming / erasing an image, and capable of holding a stable image over time in the environment of daily life. I didn't. However, the present applicant has proposed a reversible heat-sensitive recording material using a novel reversible developer in Japanese Patent Application No. 347032/1992. With this, it has a good image contrast and can form and erase images.
A reversible thermosensitive recording material capable of holding a stable image with time in an environment of daily life was first proposed.

However, in order for the reversible thermosensitive recording material to achieve the high sensitivity of G3 standard for fax applications and to satisfy the repeated durability, not only the durability such as heat resistance of the support is required. It has also been required to devise an undercoat layer between the support and the reversible thermosensitive layer. As an example of a proposal for improving this type of repeated durability, Japanese Patent Application Laid-Open No. Hei 5
-8539 discloses that an undercoat layer made of a water-soluble polymer is provided between a base paper as a support and a heat sensitive layer. However, even after this, the number of repetitions was 10 at most, which was not satisfactory as a reversible thermosensitive recording material.

[0010]

An object of the present invention is to form / erase an image with good contrast, hold a stable image over time in an environment of daily life, and improve sensitivity and repetitive durability. An object is to provide an excellent reversible thermosensitive recording material.

[0011]

Means for Solving the Problems As a result of research to solve this problem, the present inventors have found that a colorless or light-colored dye precursor is usually present on a support and that the cooling rate after heating causes a difference. In a reversible thermosensitive recording material provided with a reversible thermosensitive layer containing a reversible developer that causes a reversible color change in a dye precursor, hollow particles are formed between the support and the reversible thermosensitive layer. By providing the undercoat layer containing the reversible thermosensitive recording material, it was possible to obtain the desired sensitivity and repeat durability.

The reversible thermosensitive recording material of the present invention will be described below.

The reversible thermosensitive recording material of the present invention is characterized in that an undercoat layer containing hollow particles is provided in order to repeatedly improve durability and sensitivity. Next, the hollow particles used for the undercoat layer will be described.

Examples of the material of the hollow particles used for the undercoat layer include polymers such as polystyrene, styrene-acryl copolymer, polyethylene, polypropylene, melamine-formalin resin and various nylons.
As a method for making the inside of the particles hollow, various known methods can be mentioned. The hollow interior may be a liquid such as water, a gas such as air or nitrogen, or a mixture thereof. The number of hollows may be one or plural per particle, but the hollow ratio in volume is 20.
% Or more, particularly 30% or more is preferable for improving the sensitivity. If the hollow ratio is less than 20%, the sensitivity improving effect may be insufficient. The hollow ratio here is a volume average value when the hollow particles are formed into an aqueous dispersion or emulsion. Two or more kinds of these hollow particles may be used in combination. The average particle size of the hollow particles is 10 microns or less, more preferably 8
Micron or less is preferable because it improves print quality and repeatability. There is no particular lower limit on the characteristics of the average particle size of the hollow particles, but the hollow particles that can be stably produced and used in the present invention are about 0.1 micron. The hollow particles used in the present invention may be in a state in which the hollow portion communicates with the outside due to holes or breaks in the membrane wall of the particles.

As other materials used for the undercoat layer, for example, diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, basic magnesium carbonate, titanium oxide, zinc oxide, silicon oxide,
Aluminum hydroxide, calcium silicate, barium sulfate,
Inorganic pigments such as calcium sulfate are included. Further, for example, corn starch, rice starch, grain starches such as wheat starch, and polystyrene or benzoguanamine resin, polyethylene resin, polypropylene resin, silicone resin, urea-formalin resin or synthetic or natural resin powder such as pine resin. An organic pigment consisting of You may use 2 or more types of these pigments together. The undercoat layer may contain components added to the reversible heat-sensitive layer, the protective layer, and the like, which will be described later.

If desired, a water-soluble polymer or latex can be used in the undercoat layer. Specific examples of the water-soluble polymer include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, sodium polyacrylate, acrylic acid amide / acrylic acid ester copolymer,
Water-soluble polymers such as acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, alkali salt of styrene / maleic anhydride copolymer, alkali salt or ammonium salt of ethylene / maleic anhydride copolymer, and the like. To be As the latex, polyvinyl acetate, polyurethane, polyacrylic acid ester, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer,
Examples include, but are not limited to, methyl acrylate / butadiene copolymer, ethylene / vinyl acetate copolymer, ethylene / vinyl chloride copolymer, polyvinyl chloride, ethylene / vinylidene chloride copolymer, polyvinylidene chloride, and the like. Not a thing. These water-soluble polymers or latexes can also be used in the reversible thermosensitive layer according to the present invention.
The water-soluble polymer or latex used in each of the undercoat layer and the reversible thermosensitive layer may be the same or different. Interestingly, even if only a water-soluble polymer or a latex or a combination of both is applied as an undercoat layer, the image density is lowered and the desired repeated durability cannot be obtained. However, by using hollow particles, not only high sensitivity but also repeated durability is improved. It was difficult to predict the effect on both the sensitivity and the repeated durability.

When a water-soluble polymer, a latex or a mixture thereof is used, the amount used is not more than 200% by weight, more preferably not more than 100% by weight with respect to the hollow particles, which is effective for repeated durability. From the viewpoint of adhesive strength, it is preferably 5% or more, more preferably 10% or more. However, the weight of the hollow particles here includes a liquid such as water when it is contained therein.

As a means for incorporating hollow particles into the undercoat layer, a hollow particle emulsion is prepared by a known method, or the hollow particles are made into an aqueous dispersion liquid together with a known dispersant, etc., if necessary. There is a method of coating on a support together with a polymer, a latex or a mixture thereof. The coating amount of the undercoat layer is preferably 0.5 g or more and 20 g or less per square meter (a value excluding volatile components such as water inside the hollow particles). If it is less than that, the effect on sensitivity and repeated durability is not sufficient. or,
If it exceeds this range, it may be difficult to obtain a smooth surface uniformly.

As the support used in the reversible thermosensitive recording material of the present invention, paper, various non-woven fabrics, woven fabrics, synthetic resin films such as polyethylene terephthalate and polypropylene, synthetic resin films such as polyethylene, polypropylene and polyethylene terephthalate are laminated. The laminated paper, the synthetic paper, the metal foil, the glass, or the like, or the composite sheet in which these are combined can be optionally used according to the purpose, but the invention is not limited thereto. These may be opaque, transparent or translucent.
In order to make the background look white or other specific color, a white pigment, a colored dye or pigment, or bubbles may be contained in the support or on the surface. In particular, when the hydrophilicity of the support is small and it is difficult to apply the reversible thermosensitive recording layer when aqueous coating such as films is performed, hydrophilic treatment of the surface by corona discharge etc. or coating of various polymers on the surface of the support, etc. The easy adhesion treatment may be performed. In addition to this, a treatment necessary for curl correction, antistatic property, or improvement of running property may be performed.

The dye precursor used in the reversible thermosensitive layer according to the present invention is not particularly limited as long as it is a basic dye precursor used for recording materials such as general thermal paper and pressure-sensitive paper. Specific examples of the dye precursor used in the present invention are shown below, but the present invention is not limited thereto.

(1) Triarylmethane compound 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3-
(1,2-dimethylindol-3-yl) phthalide,
3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindole-
3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindole-3-)
Yl) -6-Dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -5 -Dimethylaminophthalide, 3-p
-Dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6-dimethylaminophthalide and the like,

(2) Diphenylmethane compound 4,4'-bis (dimethylaminophenyl) benzhydryl benzyl ether, N-chlorophenyl leuco auramine, N-2,4,5-trichlorophenyl leuco auramine, etc.

(3) Xanthene compound Rhodamine B anilinolactam, rhodamine B p-chloroanilinolactam, 3- (N-ethyl-N-tolyl) amino-6-methyl-7-anilinofluorane, 3
-(N-ethyl-N-tolyl) amino-6-methyl-7
-Phenethylfluorane, etc.

(4) Spiro compounds 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho- (3 -Methoxybenzo) spiropyran, 3-propylspirobenzopyran, etc.,

(5) Fluoran compounds 3-diethylamino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-ani Rinofluorane, 3-diethylamino-6-methyl-7- (4
-Methylanilino) fluorane, 3-diethylamino-
6-methyl-7- (4-n-butylanilino) fluorane, 3-diethylamino-6-methyl-7- (4-ethoxyanilino) fluorane, 3-pyrrolidino-6-methyl-7- (4-methylanilino) fluorane , 3-pyrrolidino-6-methyl-7- (4-n-butylanilino)
Fluoran, 3-pyrrolidino-6-methyl-7- (4-
Ethoxyanilino) fluorane, 3-di-n-propylamino-6-methyl-7-anilinofluorane, 3-di-n-butylamino-6-methyl-7-anilinofluorane, 3-di- n-pentylamino-6-methyl-7-
Anilinofluorane, 3- (N-methyl-Nn-propyl) amino-6-methyl-7-anilinofluorane,
3- (N-ethyl-Nn-propyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N)
-Isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-isobutyl) amino-
6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-tetrahydrofuran-2-ylmethyl) Amino-6-methyl-7-
Anilinofluorane, 3- (N-ethyl-N-tetrahydrofurylmethyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-tetrahydrofuran-2-yl) amino-6- Methyl-7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofuryl)
Amino-6-methyl-7-anilinofluorane, 3-dimethylamino-6-methyl-7-anilinofluorane,
3- (N-methyl-N-ethyl) amino-6-methyl-
7-anilinofluorane, 3-pyrrolidino-7-cyclohexylaminofluorane, 3-isopentylamino-
6-methyl-7-anilinofluorane, 3-di-n-butylamino-6-methyl-7- (2-fluoroanilino) fluorane, 3-dibutylamino-6-methoxy-
7-anilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-di-n-butylamino-6-methyl-7- (2,6-dimethylanilino) fluorane, 3- (N- Ethyl-N-3-ethoxypropyl) amino-6-methyl-7-anilinofluorane, 3
-(N-methyl-N-3-ethoxypropyl) amino-
6-methyl-7-anilinofluorane, 3-diethylamino-7-n-octylaminofluorane, 3-diethylamino-6-methyl-7- (3-trifluoromethylanilino) fluorane, 3-diethylamino-7 -(3
-Trifluoromethylanilino) fluorane, 3-diethylamino-7- (2-chloroanilino) fluorane,
3-diethylamino-7- (3-chloroanilino) fluorane, 3-diethylamino-7- (2-fluoroanilino) fluorane, 3-diethylamino-7- (2-methoxyanilino) fluorane, 3-pyrrolidino-7-
(2-chloroanilino) fluorane, 3-pyrrolidino-
7- (3-chloroanilino) fluorane, 3-pyrrolidino-7- (2-methoxyanilino) fluorane, 3-diethylamino-7- (2-isopentyloxycarbonylanilino) fluorane, 3-diethylamino-7-phenylfluor Olane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-chloro-7-methylfluorane, 3-diethylamino-6-methyl-7-
Chlorofluorane, 3-diethylamino-7- (3,4
-Dichloroanilino) fluorane, 3-ethylamino-
6-chlorofluorane, 3-cyclohexylamino-6
-Chlorofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-di-n-butylamino-7
-(2-chlorobenzylamino) fluorane, 3- (N
-Ethyl-Np-tolyl) amino-6-methyl-7-
Anilino Fluoran,

(6) Compounds having other structures 3- (4-dimethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide, 3-
Indolylphthalide such as (4-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide and 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide Kind. 3 ', 6'-bisdiethylamino-5-diethylaminospiro (isobenzofuran-1,9'-fluorene) -3-one, 3', 6 '
-A compound having a fluorene skeleton such as bisdimethylamino-5-dimethylaminospiro (isobenzofuran-1,9'-fluorene) -3-one. 3,3-bis- [2-
Examples thereof include vinylogous compounds of triarylmethane compounds such as (4-methoxyphenyl) -2- (4-dimethylaminophenyl) ethenyl] -4,5,6,7-tetrachlorophthalide, and these are independent. Alternatively, two or more kinds can be mixed and used.

The reversible developer used in the reversible thermosensitive layer according to the present invention causes a reversible color tone change which can be retained due to the difference in cooling rate after heating in the presence of the dye precursor. If it is, it can be used without particular limitation. From the viewpoint of color density and decoloring property, a compound represented by the following general formula 1 described in Japanese Patent Application No. 347032/1992 by the present applicant is preferably used. Specific examples thereof will be given below, but the present invention is not limited thereto.

[0028]

[Chemical 1]

In Formula 1, n is an integer of 1 or more and 3 or less, and m
Represents an integer of 0 or 1. R ¹ and R ² represent a substituent selected from an aliphatic hydrocarbon group, an alkoxy group, a halogen atom or a hydrogen atom, and may be the same or different from each other. R ³ represents an aliphatic hydrocarbon group. Y is a group represented by Formula 2.

Further, among compounds represented by Formula 1, it is preferably large number of carbon atoms in R ^3, carbon number of R ³ is 5 or less is not sufficient decoloring effect. Further, R ³ having 23 or more carbon atoms has a high production cost, and therefore R ³ is particularly preferably an aliphatic hydrocarbon group having 6 or more and 22 carbon atoms or less.

[0031]

[Chemical 2]

In Formula 2, l1 and l2 each represent an integer of 0 or 1. X ¹ and X ² each represent a divalent group having at least one hetero atom and may be the same or different. Ar represents an aromatic group which may have a substituent.

The compound represented by the general formula 1 is an electron-accepting compound, and has a specific decoloring effect, that is, a reversible effect, although it has the ability to color the dye precursor. Incidentally, electron-accepting compounds used in ordinary heat-sensitive recording materials, that is, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl)
No such reversible effect is observed with sulfone, benzyl 4-hydroxybenzoate and the like. Next, specific examples of preferred electron-accepting compounds as the reversible developer according to the present invention will be given, but the present invention is not limited thereto.

4'-hydroxyheptane anilide, 4 '
-Hydroxy-3-methyloctaneanilide, 4'-hydroxytridecaneanilide, 4'-hydroxyheptadecaneanilide, 4'-hydroxynonadecaneanilide, 3'-hydroxynonadecaneanilide, 4'-hydroxy-10-octadecene Anilide, 4'-hydroxy-docassananilide, 15-cyclohexyl-4'-
Hydroxy pentadecane anilide, 4'-hydroxy-
5-Tetradeceneanilide, 4'-hydroxy-3'-
Methylnonaneanilide, 3'-cyclohexyl-4'-
Hydroxyheptadecane anilide, 3'-allyl-4 '
-Hydroxypentadecaneanilide, 4'-hydroxy-3'-methoxyoctadecaneanilide, 3'-chloro-4'-hydroxyoctadecaneanilide, 3'-hydroxydodecaneanilide, 2 ', 4'-dihydroxyheptadecaneanilide,

4'-hydroxy-4-hexylbenzanilide, 4'-hydroxy-4-dodecylbenzanilide, 4'-hydroxy-4-tetradecylbenzanilide, 4'-hydroxy-4-octadecylbenzanilide, 4 '. -Hydroxy-4-pentadecylaminocarbonylbenzanilide, 4'-hydroxy-4-hexylcarbonylaminobenzanilide, 4'-hydroxy-
4- (heptylthio) benzanilide, 4'-hydroxy-4-octadecyloxybenzanilide, 4'-hydroxy-4-dodecylsulfonylbenzanilide,
4'-hydroxy-4-nonylsulfonyloxybenzanilide, 4'-hydroxy-4-dodecyloxysulfonylbenzanilide, 4'-hydroxy-4-pentadecylaminosulfonylbenzanilide, 4'-hydroxy-4- (N- Pentadecylideneamino) benzanilide, 4'-hydroxy-4- (N-heptadecylideneamino) benzanilide,

4'-hydroxy-3,4-dioctyloxybenzanilide, 4'-hydroxy-3,4,5-
Trioctadecyloxybenzanilide, 4'-hydroxy-3-octyl-4- (octylthio) benzanilide, 4'-hydroxy-3- (heptadecylthio)-
5-pentadecyloxybenzanilide, 4'-hydroxy-3-heptadecylcarbonylamino-5-dodecylbenzanilide, 4'-hydroxy-3-octadecylaminocarbonyl-5-tetradecylaminocarbonylbenzanilide, 4'-hydroxy -3-Octadecylsulfonylamino-5-octadecyloxybenzanilide, 4'-hydroxy-3-heptadecyloxysulfonyl-5-tetradecyloxysulfonylbenzanilide, 4'-hydroxy-3,5-bis (N-docosyri) Denamino) Benzanilide,

4'-hydroxy-4-octadecylcarbonylaminobenzanilide, 4'-hydroxy-3-
Octadecylcarbonylamino-5-octadecyloxybenzanilide, 4'-hydroxy-3'-methyl-
4-nonylbenzanilide, 3'-allyl-4'-hydroxy-4-pentadecylbenzanilide, 4'-hydroxy-3'-methoxy-4-octadecylbenzanilide, 4'-hydroxy-3'-methyl-4 -Nonyloxybenzanilide, 4'-hydroxy-3'-propyl-4-nonadecylcarbonyloxybenzanilide,
3'-butyl-4'-hydroxy-4-octadecyloxycarbonylbenzanilide, 3'-hydroxy-4
-Pentadecylcarbonyloxybenzanilide, 3 '
-Hydroxy-4-nonadecylsulfonylbenzanilide, 3 ', 4'-dihydroxy-4-heptadecylsulfonyloxybenzanilide, 3', 4 ', 5'-trihydroxy-4-tetracosylaminosulfonylbenzanilide, 3 ', 5'-dihydroxy-4-pentacosylaminocarbonylbenzanilide, 3'-hydroxy-4- (N-dodecylideneamino) benzanilide, N
-[4- (3-hydroxyphenylaminocarbonyl)
Benzylidene] pentadecylamine,

N-cyclohexyl-4-hydroxybenzamide, N-cyclohexylmethyl-4-hydroxybenzamide, N-octyl-4-hydroxybenzamide, N-dodecyl-4-hydroxybenzamide, N
-Octadecyl-4-hydroxybenzamide, N-methyl-N-octadecyl-4-hydroxybenzamide, N-octacosyl-4-hydroxybenzamide,
N- (3-methylhexyl) -4-hydroxybenzamide, N- (8-octadecenyl) -4-hydroxybenzamide,

4-hydroxy-4'-dodecylbenzanilide, 4-hydroxy-4'-tetradecylbenzanilide, N-methyl-4-hydroxy-4'-octadecylbenzanilide, 4-hydroxy-4'-octyloxy Benzanilide, 4-hydroxy-4'-octadecyloxybenzanilide, 4-hydroxy-4'-
(Octadecylthio) benzanilide, 4-hydroxy-4'-pentylcarbonylbenzanilide, 4-hydroxy-4'-hexadecylcarbonylbenzanilide, 4-hydroxy-4'-heptadecyloxycarbonyloxybenzanilide, 4-hydroxy- 4'-dodecyloxycarbonylbenzanilide, 4-hydroxy-4'-docosyloxycarbonylbenzanilide,
4-hydroxy-4'-heptadecylcarbonyloxybenzanilide, 4-hydroxy-4'-cyclohexylaminobenzanilide, 4-hydroxy-4'-octylaminobenzanilide, 4-hydroxy-4'-octadecylaminobenzanilide,

4-hydroxy-4'-heptylcarbonylaminobenzanilide, 4-hydroxy-4'-heptadecylcarbonylaminobenzanilide, 4-hydroxy-4'-octadecylaminocarbonylbenzanilide, 4-hydroxy-4'- (8-octadecenyl)
Aminocarbonylbenzanilide, 4-hydroxy-
4'-dodecylsulfonylbenzanilide, 4-hydroxy-4'-octyloxysulfonylbenzanilide, 4-hydroxy-4'-octadecyloxysulfonylbenzanilide, 4-hydroxy-4'-dodecylsulfonyloxybenzanilide, N-4 -Hydroxybenzoyl-N'-octadecylidene-1,4-
Phenylenediamine, N-4- (4-hydroxyphenylcarbonylamino) benzylidenedecylamine, 4,
-Hydroxy-4'-octyloxycarbonylaminobenzanilide, 4-hydroxy-4'-tetradecyloxycarbonylaminobenzanilide, 4-hydroxy-4'-octadecylureylenebenzanilide,

N-dodecyl-3-hydroxybenzamide, N-octadecyl-3,4-dihydroxybenzamide, N-octadecyl-2,3,4-trihydroxybenzamide, 3-hydroxy-4'-dodecyloxybenzanilide, N -Methyl-4-hydroxy-3'-
Octadecyloxybenzanilide, 3-hydroxy-
4'-octylbenzanilide, 3-hydroxy-4 '
-Tetradecylbenzanilide, N-methyl-3-hydroxy-4'-octadecylbenzanilide, N-dodecyl-4-hydroxy-3-methylbenzamide, 3-
Methoxy-4-hydroxy-4'-octadecyloxybenzanilide, 3-allyl-4-hydroxy-4'-
Octadecyloxybenzanilide, 3-chloro-4-
Hydroxy-4'-octadecylbenzanilide, N-
Octadecyl-4-hydroxy-2,5-dimethylbenzamide, N-octadecyl-4-hydroxy-3-ethylbenzamide, 4-hydroxy-4'-octyloxy-3'-methylbenzanilide, 4-hydroxy-
4'-octadecyloxy-3'-chlorobenzanilide, 4-hydroxy-3 ', 4'-didecyloxybenzanilide, 4-hydroxy-3'-octadecylamino-4'-octadecyloxybenzanilide, 4-hydroxy -2'-chloro-3 ', 5'-didecyloxybenzanilide, 4-hydroxy-3', 4'-dioctadecyloxybenzanilide, 4-hydroxy-4 '
-Octyl-3'-methylbenzanilide, 3-hydroxy-4-methyl-4'-tetradecylbenzanilide, N-methyl-4-hydroxy-3'-octadecylbenzanilide,

4- (N-octylsulfonylamino) phenol, 4- (N-dodecylsulfonylamino) phenol, 4- (N-octadecylsulfonylamino) phenol, 4- (N-methyl-N-octadecylsulfonylamino) phenol , 4- (N-3-methylhexylsulfonylamino) phenol, 4'-hydroxy-
4-cyclohexylbenzenesulfonanilide, 4'-
Hydroxy-4-octylbenzenesulfonanilide,
4'-hydroxy-4-dodecylbenzenesulfonanilide, 4'-hydroxy-4-dodecyloxybenzenesulfonanilide, 4'-hydroxy-4-octadecyloxybenzenesulfonanilide, 4'-hydroxy-4- (dodecylthio) benzenesulfone Anilid,
4'-hydroxy-4-hexylcarbonylbenzenesulfonanilide, 4'-hydroxy-4-hexadecylcarbonylbenzenesulfonanilide, 4'-hydroxy-4- (8-heptadecenyl) carbonylbenzenesulfonanilide, 4'-hydroxy-4 -Octyloxycarbonyloxybenzenesulfonanilide, 4'-
Hydroxy-4-dodecyloxycarbonylbenzenesulfonanilide, '-hydroxy-4-octacosyloxycarbonylbenzenesulfonanilide, 4'-hydroxy-4-dodecylcarbonyloxybenzenesulfonanilide, 4'-hydroxy-4-hexylaminobenzene Sulfone anilide, 4'-hydroxy-4-octadecylaminobenzene sulfone anilide,

4'-hydroxy-4-heptadecylcarbonylaminobenzenesulfonanilide, 4'-hydroxy-4-dodecylaminocarbonylbenzenesulfonanilide, 4'-hydroxy-4-dodecylsulfonylbenzenesulfonanilide, 4'-hydroxy- 4-octyloxysulfonylbenzenesulfonanilide,
4'-hydroxy-4-octadecyloxysulfonylbenzenesulfonanilide, 4'-hydroxy-4-dodecylsulfonyloxybenzenesulfonanilide, N
-Octylidene-4- (4-hydroxyphenyl) aminosulfonylaniline, N-dodecylidene-4- (4-
Hydroxyphenyl) aminosulfonylaniline, N-
4- (4-hydroxyphenylaminosulfonyl) benzylidene octadecylamine, 4'-hydroxy-4-
Octyloxycarbonylaminobenzenesulfonanilide, 4'-hydroxy-4-octadecyloxycarbonylaminobenzenesulfonanilide, 4'-hydroxy-4-octadecylureylenebenzenesulfonanilide,

3- (N-dodecylsulfonylamino) phenol, 4- (N-octadecylsulfonamino) catechol, 4- (N-octadecylsulfonamino) resorcinol, 4- (N-octadecylsulfonylamino) pyrogallol, 4'- Hydroxy-3-octyloxybenzenesulfonanilide, 3'-hydroxy-4
-Dodecyloxybenzenesulfonanilide, N-methyl-4'-hydroxy-3-octadecyloxybenzenesulfonanilide, 3'-hydroxy-4-dodecylbenzenesulfonanilide, 3-methyl-4- (N-dodecylsulfonamino) phenol , 4-methyl-3-
(N-tetradecylsulfonamino) phenol, 3 '
-Methoxy-4'-hydroxy-4-octadecyloxybenzenesulfonanilide, 3'-chloro-4'-hydroxy-4-octadecylbenzenesulfonanilide, 4'-hydroxy-2,5-dimethyl-4-octadecylbenzenesulfonanilide , 3-methyl-4-
(N-octadecylsulfonamino) phenol, 4 '
-Hydroxy-3,4-dioctadecyloxybenzenesulfonanilide,

1- (4-hydroxyphenylthio) hexane, 1- (4-hydroxyphenylthio) dodecane,
1- (4-hydroxyphenylthio) octadecane, 1
-(3-hydroxyphenylthio) octadecane, 1-
(4-hydroxyphenylthio) docosane, 1- (4-
Hydroxyphenylthio) tetracosane, 2-heptyl-1- (4-hydroxyphenylthio) octane, 1-
(4-hydroxyphenylthio) -9-octadecene,
1- (4-hydroxy-3-methylphenylthio) octadecane, 1- (3-allyl-4-hydroxyphenylthio) hexadecane, 1- [4-hydroxy-3-
(1,1-Dimethylethyl) phenylthio] tetracosane, 1- (4-hydroxy-3-methoxyphenylthio) octadecane, 1- (2-ethoxy-4-hydroxyphenylthio) octadecane, 1- (3-chloro-4)
-Hydroxyphenylthio) octadecane, 1- (2-
Fluoro-4-hydroxyphenylthio) octadecane, 1- (2-hydroxyphenylthio) octane, 1
-(3-hydroxyphenylthio) octadecane, 1-
(3,4-dihydroxyphenylthio) octadecane,
1- (3,4-dihydroxyphenylthio) icosane,

4'-hydroxy-4-hexyldiphenyl sulfide, 4'-hydroxy-4-dodecyl diphenyl sulfide, 4'-hydroxy-4-tetradecyl diphenyl sulfide, 4'-hydroxy-4-octadecyl diphenyl sulfide, 4 ' -Hydroxy-4-
Octadecylcarbonylaminodiphenyl sulfide,
4'-hydroxy-4-dodecyloxydiphenyl sulfide, 4'-hydroxy-4-octadecyloxydiphenyl sulfide, 4'-hydroxy-4-dodecylsulfonyldiphenyl sulfide, 4'-hydroxy-
4-Octadecyloxysulfonyldiphenyl sulfide, 4'-hydroxy-4-octadecylsulfonylaminodiphenyl sulfide, 4'-hydroxy-4-tridecylcarbonyldiphenyl sulfide, 4'-hydroxy-4- (N-heptadecylideneamino) diphenyl Sulfide,

4'-hydroxy-3,4-didecyloxydiphenyl sulfide, 4'-hydroxy-3,4-
Dioctadecyloxydiphenyl sulfide, 4'-hydroxy-3-octyl-4- (octylthio) diphenyl sulfide, 4'-hydroxy-3-octadecyl-5-tridecylsulfonyldiphenyl sulfide,
4'-hydroxy-3- (heptadecylthio) -5-pentadecyloxydiphenyl sulfide, 4'-hydroxy-3-heptadecylcarbonylamino-5-dodecyldiphenyl sulfide, 4'-hydroxy-3-octadecylcarbonylamino-5- Octadecyloxydiphenyl sulfide, 4'-hydroxy-3-heptadecyloxysulfonyl-5-tetradecyloxysulfonyl diphenyl sulfide, 4'-hydroxy-3,5
-Bis (N-docosylideneamino) diphenyl sulfide, 4- (15-cyclohexylpentadecyl) -4 '
-Hydroxydiphenyl sulfide, 4'-hydroxy-4- (5-tetradecenyl) diphenyl sulfide,
4'-hydroxy-4- (10-octadecenyloxycarbonyl) diphenyl sulfide, 4'-hydroxy-3'-methyl-4-nonyldiphenyl sulfide,

3'-allyl-4'-hydroxy-4-pentadecyldiphenyl sulfide, 3'-chloro-4 '
-Hydroxy-4-octadecyldiphenyl sulfide, 3'-chloro-4'-hydroxy-4-octadecyl-5-pentadecyloxydiphenyl sulfide,
4'-hydroxy-3'-methyl-4-nonyloxydiphenyl sulfide, 4'-hydroxy-3 '-(1-
Methylethyl) -4-pentacosylsulfonylaminodiphenyl sulfide, 4'-hydroxy-3 '-(2-
Methylpropyl) -4-nonadecyloxysulfonyl diphenyl sulfide, 3'-hydroxy-4-dodecyl diphenyl sulfide, 3'-hydroxy-4-octadecyl diphenyl sulfide, 2 ', 4'-dihydroxy-4-heptadecyl diphenyl sulfide, 3 ',
4'-dihydroxy-4-heptadecyl diphenyl sulfide, 3'-hydroxy-4-dodecyloxycarbonyl diphenyl sulfide,

N- (4-hydroxyphenyl) -N'-
Hexyl urea, N- (4-hydroxyphenyl) -N '
-Octylurea, N- (4-hydroxyphenyl)-
N'-dodecyl urea, N- (4-hydroxyphenyl)
-N'-octadecyl urea, N- (4-hydroxyphenyl) -N'-docosyl urea, N- (4-hydroxyphenyl) -N '-(2-heptyloctyl) urea, N-
(4-hydroxyphenyl) -N '-(14-cyclohexyltetradecyl) urea, N- (3-methyl-4-hydroxyphenyl) -N'-octadecylurea, N-
(4-Hydroxyphenyl) -N '-(9-octadecenyl) urea, N- (3-allyl-4-hydroxyphenyl) -N'-octadecylurea, N- [3- (1,1-
Dimethylethyl) -4-hydroxyphenyl] -N'-
Octadecyl urea, N- (3,5-dimethyl-4-hydroxyphenyl) -N'-octadecyl urea, N- (2
-Hydroxyphenyl) -N'-octylurea, N-
(3-hydroxyphenyl) -N'-octadecyl urea, N- (3,4-dihydroxyphenyl) -N'-octadecyl urea, N- (3,4,5-trihydroxyphenyl) -N'-tricosyl urea, N- (4-hydroxyphenyl) -N '-(4-tetradecylphenyl) urea, N- (4-hydroxyphenyl) -N'-(4-hexylphenyl) urea, N- (4-hydroxyphenyl)- Examples thereof include N '-(3,4-dioctadecylphenyl) urea.

These reversible developers may be used alone or in admixture of two or more, and the amount of the reversible developer based on the dye precursor is 5 to 5000% by weight, preferably It is 50 to 1000% by weight.

Next, the components that may be contained in the reversible thermosensitive layer according to the present invention will be described.

Examples of the pigment include white pigments or colorless pigments, and colored pigments other than the coloring hue and pigments having metallic luster depending on the use. Specific examples of pigments that can be used include diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, basic magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, urea-formalin resin, polystyrene. , Pigments such as various grain starches. In addition to the above, the reversible thermosensitive layer may contain the hollow particles listed in the section of the description of the undercoat layer. The average particle size of the pigment is preferably 10 microns or less from the viewpoint of printing quality. Those having a thickness of 0.1 micron or more, particularly 5 microns or more are preferable from the viewpoint of improving repeated durability. However, particles having a particle size outside this range can also be used in the present invention. The amount of the pigment added is preferably 500% by weight or less, and more preferably 300% by weight or less based on the dye precursor, from the viewpoint of further increasing the sensitivity. On the other hand, if the amount added exceeds this range, the sensitivity may be lowered and the image density may be lowered.
Further, it is preferably 20% by weight or more, more preferably 30% by weight or more in terms of sensitivity and repeated durability. If it is less than this, the effect due to the addition of the pigment may be insufficient with respect to either or both of sensitivity and repeated durability. Two or more pigments may be used in combination.

It is also possible to add a binder to the reversible heat-sensitive layer for the purpose of improving the strength of the reversible heat-sensitive layer. Specific examples of the binder include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, sodium polyacrylate, acrylic acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic. Water-soluble polymer such as acid ester / methacrylic acid terpolymer, alkali salt of styrene / maleic anhydride copolymer, alkali salt of ethylene / maleic anhydride copolymer, polyvinyl acetate, polyurethane, polyacrylic acid Ester, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, ethylene / vinyl acetate copolymer, ethylene / vinyl chloride copolymer, polyvinyl chloride, ethylene Vinylidene chloride copolymers, such as latex of polyvinylidene chloride and the like but not limited thereto.

A heat-fusible substance may be contained in the reversible thermosensitive layer as an additive for controlling the color developing sensitivity and the decoloring temperature of the reversible thermosensitive layer. 60 ℃ ~ 200
Those having a melting point of ℃ are preferable, and especially 80 to 180
Those having a melting point of ° C are preferred. It is also possible to use a sensitizer which is used for general thermal recording paper. Examples of these compounds include waxes such as N-hydroxymethylstearic acid amide, stearic acid amide, and palmitic acid amide, naphthol derivatives such as 2-benzyloxynaphthalene, and biphenyl derivatives such as p-benzylbiphenyl and 4-allyloxybiphenyl. , 1,2-bis (3-methylphenoxy) ethane, 2,2'-bis (4
-Methoxyphenoxy) diethyl ether, bis (4-
Polyether compounds such as methoxyphenyl) ether,
Examples thereof include carbonic acid such as diphenyl carbonate, dibenzyl oxalate, and bis (p-methylbenzyl oxalate) ester, or an oxalic acid diester derivative, and it is possible to add two or more kinds in combination.

Next, a specific method for producing the reversible thermosensitive recording material of the present invention will be described, but the present invention is not limited thereto. Specific examples of the method for producing the reversible thermosensitive recording material of the present invention include a dye precursor and a reversible color developer on an undercoat layer formed by coating and drying an undercoat coating liquid containing hollow particles on a support. A method of forming a reversible heat-sensitive layer by smearing a reversible heat-sensitive coating liquid containing a reversible heat-sensitive layer component containing an agent as a main component and drying it. Each layer can be formed by a conventional method. The smearing method may be the same or different and is not particularly limited. For example, a smearing device such as an air knife coater, a blade coater, a bar coater, a curtain coater, a planographic printing plate, a relief printing plate,
It is possible to use various printing machines using intaglio, flexo, gravure, screen, hot melt, and the like. In the hot melt method, each component is mixed and heated without using a solvent or a dispersion medium to melt a fusible component and apply it while hot.

The reversible heat-sensitive coating liquid containing a dye precursor and a reversible developer as main components may be prepared by dissolving each compound in a solvent or dispersing it in a dispersion medium and then mixing each compound. A method of mixing the compounds and then dissolving in a solvent or dispersing in a dispersion medium, a method of dissolving each compound by heating and homogenizing and then cooling, and dissolving in a solvent or dispersing in a dispersion medium, etc. is not. At the time of dispersion, a dispersant may be used if necessary. When water is the dispersion medium, examples of the dispersant include water-soluble polymers such as polyvinyl alcohol and various surfactants. A water-soluble organic solvent such as ethanol may be mixed when the aqueous dispersion is performed. In addition to this, when an organic solvent represented by hydrocarbons is a dispersion medium, lecithin, phosphoric acid esters or the like may be used as a dispersant.

The layer structure of the reversible thermosensitive recording material of the present invention is as follows:
If necessary, a protective layer may be provided on the reversible thermosensitive layer. The protective layer is formed mainly of a film-forming material such as polyvinyl alcohol, which is listed in the description of the binder of the reversible thermosensitive layer, such as a water-soluble polymer and latex. In that case, a compound having an epoxy group, a hardening agent such as zirconium salt, or a crosslinking agent can be added. In addition, a light and electron beam curable resin or a thermosetting resin may be smeared and cured to form a protective layer. Alternatively, a film may be laminated to form a protective layer. For example, the various films mentioned in the section of description of the support are used for lamination. In any of the above cases, the pigments described below may be blended in order to further improve the writability, the running property or the repeated durability. The average particle size of the pigment used in the protective layer is preferably 0.4 μm or less because the image density is increased. The protective layer may be composed of a plurality of layers of 2 layers or 3 layers or more. The reversible heat-sensitive layer may also be a multi-layer having two or more layers by containing each component one by one or by changing the compounding ratio for each layer. Further, in the reversible heat-sensitive layer and / or on the surface opposite to the surface on which the other layer and / or the reversible heat-sensitive layer is provided, a material capable of electrically, optically and magnetically recording information may be contained. good. Further, a back coat layer may be provided on the surface opposite to the surface on which the reversible heat-sensitive layer is provided for the purpose of blocking prevention, curling prevention, antistatic prevention and the like.

For the protective layer, diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, basic magnesium carbonate, titanium oxide, zinc oxide,
Pigments such as silicon oxide, aluminum hydroxide and urea-formalin resin may be contained. These pigments may also be included in the reversible heat-sensitive layer, the undercoat layer or the backcoat layer. In addition, for each layer, higher fatty acid metal salts such as zinc stearate, calcium stearate and barium stearate, waxes such as paraffin, paraffin oxide, polyethylene, polyethylene oxide, stearamide, castor wax, etc., and sodium dioctyl sulfosuccinate. It is also possible to contain a dispersant such as a surfactant, a surfactant, a fluorescent dye or pigment, a colored dye or pigment, and the like.

Next, a method of coloring and decoloring the reversible thermosensitive recording material of the present invention will be described. In order to develop a color, rapid cooling may occur after heating, and for example, heating with a thermal head, laser light or the like is possible. Alternatively, even by heating with a heat roll or a heat stamp or the like, color can be developed if the speed of passing the sheet is increased or if rapid cooling with a cooling roll or cold air can be performed. Also, if heated and cooled slowly, the color disappears, and for example, it is slowly heated after being heated using radiant heat from a thermal head, a heat roll, a heat stamp, high frequency heating, hot air, an electric heater, or a light source such as a tungsten lamp or a halogen lamp. It can be done by cooling.

[0060]

The present invention will be described in more detail with reference to the following examples. The numbers of parts and percentages in the examples are based on weight, except that the hollow ratio of hollow particles is a numerical value by volume. The liquid concentration of the hollow particle emulsion or dispersion is calculated by including the water inside the hollow particles in the particle weight. However, water is excluded from the weight calculation after smearing.

Example 1 (A) Preparation of Undercoat Coating Liquid Hollow particle emulsion manufactured by Rohm and Haas Japan (Rhopaque HP-91: styrene-acrylic copolymer, average particle size 1 micron, hollow ratio 50%, Liquid concentration 5
3%) 611 parts of polyvinyl alcohol 10% aqueous solution 4
An undercoat coating liquid was prepared by thoroughly mixing 86 parts and 903 parts of water.

(B) Preparation of reversible heat-sensitive coating liquid 40 parts of 3-diethylamino-6-methyl-7-anilinofluorane was added to a 2.5% polyvinyl alcohol aqueous solution 90.
The mixture was pulverized with a ball mill by a ball mill to obtain a dye precursor dispersion liquid. Then N- (4-hydroxyphenyl) -N'-n
150 parts of hexadecylurea were ball milled together with 600 parts of a 2.5% aqueous polyvinyl alcohol solution to give a reversible developer dispersion. After mixing the above two dispersions,
175 parts of 10% polyvinyl alcohol aqueous solution, water 400
Parts were added and mixed well to prepare a reversible heat-sensitive coating liquid.

(C) Preparation of reversible thermosensitive recording material The undercoat coating liquid prepared in (A) was applied to a base paper having a thickness of 170 μm and a Beck smoothness of 349 seconds to give a solid coating amount of 4.2 g / m ² . After the coating is dried, the reversible heat-sensitive coating liquid prepared in (B) is applied thereon, and the solid content of the coating is 3.3 g / m 2.
^It was smeared dry to ² and processed with a super calendar. Further, a 5% aqueous polyvinyl alcohol solution was smeared and dried to give a solid content of 1.2 g / m ² to obtain a reversible thermosensitive recording material.

Example 2 Instead of 611 parts of the hollow particle emulsion used in Example 1, a hollow particle emulsion manufactured by Rohm and Haas Japan Co. (ROPAKE OP-62: styrene-acrylic copolymer as a raw material, having an average particle size of 0. 45 micron, hollow rate 33
%, Liquid concentration 37.5%) A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that 863 parts were used.

Example 3 In place of 611 parts of the hollow particle dispersion liquid used in Example 1, a hollow particle emulsion (MMVP100 manufactured by Nippon Zeon Co., Ltd.) was used.
2: Material was styrene-acrylic, average particle size 0.48 micron, hollow ratio 48%, liquid concentration 33%) A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that 981 parts was used.

Example 4 In place of 611 parts of the hollow particle dispersion liquid used in Example 1, a hollow particle emulsion (MMVP120 manufactured by Nippon Zeon Co., Ltd.) was used.
0: Material was styrene-acrylic, average particle diameter 0.55 micron, hollow ratio 55%, liquid concentration 30%) A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that 1079 parts were used.

Example 5 N- (4-hydroxyphenyl) -used in Example 1
Instead of 150 parts of N'-n-hexadecylurea, N-
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that 150 parts of (4-hydroxyphenyl) -N'-n-docosylurea was used.

Example 6 The coating amount of the undercoat layer in Example 1 was 3.0 g /
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that m ² was used.

Example 7 The amount of undercoat layer smeared in Example 1 was 4.8 g /
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that m ² was used.

Example 8 A reversible thermosensitive material was prepared in the same manner as in Example 1 except that the dye precursor used in Example 1 was changed to 3-di-n-butylamino-6-methyl-7-anilinofluorane. A recording material was obtained.

Example 9 A white polyethylene terephthalate film having a thickness of 188 microns (Lumirror E manufactured by Toray Industries, Inc.) was used as the base paper used in Example 1.
22 # 188) except that the reversible thermosensitive recording material was obtained in the same manner as in Example 1.

Example 10 The base paper used in Example 1 was prepared by using a foamed polyethylene terephthalate film having a thickness of 188 microns (Lumirror E manufactured by Toray Industries, Inc.).
62 # 188), except that a reversible thermosensitive recording material was obtained in the same manner as in Example 1.

Example 11 A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the 10% aqueous solution of polyvinyl alcohol used in the undercoat coating liquid of Example 1 was changed to 365 parts.

Example 12 A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the 10% aqueous solution of polyvinyl alcohol used in the undercoat coating solution of Example 1 was changed to 729 parts.

Comparative Example 1 A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the undercoat layer provided in Example 1 was not provided.

Comparative Example 2 A reversible thermosensitive recording material was obtained in the same manner as in Example 1, except that the same amount of polyvinyl alcohol as in Example 1 was applied to form an undercoat layer except for the hollow particles used in Example 1. .

Sensitivity and Durability Test The reversible thermosensitive recording materials obtained in Examples 1 to 12 and Comparative Examples 1 and 2 were printed with Kyocera print head KJT-256-8MG.
Okura Electric Thermal Facsimile Printing Tester TH-with F1
An applied voltage of 26 ms with an applied pulse of 1.0 ms using PMD
Printing was performed under the condition of bolt and the image density was measured. The image was erased by passing it through a hot roll at 110 ° C to 120 ° C. This printing and erasing were repeated 100 times, and the density of the black image obtained at the 100th time was measured with a densitometer Macbeth RD91.
8 was used for measurement.

The image densities of Examples 1 to 12 were within the range of 1.0 to 1.1 in the first printing. This is a commercially available G3
It has high sensitivity comparable to standard fax thermal paper. However, the image densities of the first printing in Comparative Examples 1 and 2 were as low as 0.75 to 0.80, respectively, and it was clear that these had lower sensitivities as compared with each Example. Further, even in the 30th concentration in the middle of the repeated test, 1.20 in Examples 1 to 12.
While maintaining the above, Comparative Examples 1 and 2 all had a low concentration of about 0.80. The images of Examples 1 to 12 were still 1.20 or more even after the 100th printing.

Comparative Examples 1 and 2 have low sensitivity, and the image density of the first printing is about 1.0 which is the same level as Examples 1 to 12 when the pulse width during printing is 1.1 milliseconds. Become. Therefore, of the repeated durability test conditions, only the pulse width of the printing condition was set to 1.1 milliseconds, and the repeated durability test of these comparative examples was separately performed. However, in both cases, the image density of the first printing was about 1.0, which is at the same level as in Examples 1 to 12, but the image density had already dropped to about 0.80 at the stage of the 30th printing.

[0080]

INDUSTRIAL APPLICABILITY A reversible thermosensitive recording material containing a colorless or light-colored dye precursor and a reversible developer which causes the dye precursor to undergo reversible color tone change due to difference in cooling rate after heating. In the above, by providing an undercoat layer containing hollow particles, images can be formed / erased with good contrast, stable images can be retained over time in the environment of daily life, and sensitivity and repeatability are excellent. A reversible thermosensitive recording material could be obtained.

Claims (1)

[Claims] 1. A main component is a colorless or light-colored dye precursor on a support, and a reversible developer that causes a reversible color change in the dye precursor due to a difference in cooling rate after heating. In the reversible thermosensitive recording material provided with the reversible thermosensitive layer, an undercoat layer containing hollow particles is provided between the support and the reversible thermosensitive layer.