JP2001105731A - Thermally reversibly recording material and thremally reversibly recording medium using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermally reversibly recording material capable of economically holding a stable image even in a daily life environment, by easily and repeatedly forming and erasing the image under the control of a thermal energy and incorporating a good image contrast and a thermally reversible recording medium using it. SOLUTION: A first thermally reversibly recording layer 12, a resin layer 14, an ultraviolet absorption layer 16 and a protective layer 18 are sequentially provided on a support 10. In this case, the first layer contains a thermally reversibly recording material made of a mixture containing an electron acceptive compound, an electron donative colorational compound and a resin binder. As the acceptive compound, a 4-hydroxy-docosaneanilide is used, as the donative compound, one type selected from the group consisting of a 3-dibutyl-amino-6- methyl-7-anilinofluoran, 3-(4-diethylamino-2-ethoxy-phenyl)-3-(1-ethyl-2- methylindole-3-il)-4-azaphthalide and 3,3-bis(1-n-butyl-2-methylindole-3-il)phthalide is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoreversible recording material mainly composed of an electron accepting compound and an electron donating color developing compound, and a thermoreversible recording medium using the same.

[0002]

2. Description of the Related Art In recent years, with the spread of OA equipment, plain paper or thermal recording paper has been widely used in OA equipment such as word processors and fax machines, and has been consumed in large quantities. For this reason, from the viewpoint of reducing waste from offices or preserving the global environment, the emergence of highly practical recyclable recording media is desired.

In order to realize such a recording medium, the development of a recording medium using a thermoreversible recording material capable of repeatedly and reversibly forming and erasing an image is being developed.

Heretofore, some thermoreversible recording materials and thermoreversible recording media using the same capable of repeatedly forming and erasing such images have been disclosed in gazettes and the like. .

[0005] Reference 1 (Japanese Patent Application Laid-Open No. 63-39377) discloses a reversible recording material in which an organic low-molecular substance is dispersed in a resin binder. Was changed.

Document 2 (Japanese Patent Application Laid-Open No. 58-191190) discloses a reversible heat-sensitive transparent recording material composed of a color former and a developer, which forms an image by heating, and uses water or water vapor. To erase.

[0007] Reference 3 (Japanese Patent Application Laid-Open No. 2-188293) and Reference 4 (Japanese Patent Publication No. 7-15541) disclose reversible thermosensitive recording using a leuco dye and a color-depressing agent that causes the leuco dye to develop and decolor by heating. Materials and media are disclosed. In this case, the color-developing agent is an amphoteric compound having an acidic group for coloring the leuco dye and a basic group for decolorizing the colored leuco dye. Coloring and decoloring are performed by giving priority to one of the decoloring effects of the base.

[0008]

However, the above-mentioned prior art, despite many studies,
There are various problems.

The reversible recording material disclosed in Document 1 forms an image by utilizing the phenomenon that the transparency changes due to cloudiness due to polycrystallization of an organic low-molecular substance. For this reason, there is a problem that the contrast between the image forming portion and the image non-forming portion is insufficient.

The reversible heat-sensitive transparent recording material disclosed in Document 2 cannot control both processes of color development and decoloration only by heat energy, and thus has a problem that its handling is not easy.

The reversible thermosensitive recording materials and media disclosed in References 3 and 4 cannot completely switch between a color-forming reaction and a decoloring reaction only by controlling heat energy.
Since both reactions occur at a certain rate at the same time, a sufficient color density cannot be obtained and decoloring cannot be performed completely. For this reason,
There is a problem that a sufficient contrast cannot be obtained.

As described above, according to the conventional technique, it is not possible to obtain a thermoreversible recording material and a medium capable of obtaining a good image contrast only by controlling heat energy.

An object of the present invention is to form and erase an image easily and repeatedly by controlling thermal energy, have a good image contrast, and stabilize with time in an environment of daily life. Another object of the present invention is to provide a thermoreversible recording material capable of holding a stable image and a thermoreversible recording medium using the same. In other words, in order to realize an inexpensive and large-sized image display, image formation and erasing can be performed with low printing energy (a normal thermal printing apparatus can be used), and high contrast ( It is an object of the present invention to provide a thermoreversible recording material having heat resistance and light resistance (which can be repeatedly used in an indoor environment) and a thermoreversible recording medium using the same, which have the same level as a printed matter obtained by an ordinary printer. .

[0014]

In order to achieve this object, a number of experiments have been carried out. As a result, the combination of an electron-accepting compound and an electron-donating color-forming compound makes it possible to obtain an image by heat control alone. It was found that formation and erasing can be performed, and further, from the viewpoint of contrast and image retention, a practical thermoreversible recording material and a thermoreversible recording medium using the same can be formed.

According to the first thermoreversible recording material of the present invention, in the thermoreversible recording material comprising a mixture containing an electron accepting compound, an electron donating coloring compound and a binder resin, the electron accepting compound is The 4-hydroxydocosananilide represented by the following formula (1) and the electron-donating color-forming compound are 3-dibutylamino-6-methyl-7-anilinofluoran represented by the following formula (2).

[0016]

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[0017]

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According to the second thermoreversible recording material of the present invention, the thermoreversible recording material comprising a mixture containing an electron-accepting compound, an electron-donating color-forming compound and a binder resin has an electron-accepting property. The compound is 4-hydroxydocosananilide represented by the above formula (1), and the electron-donating color-forming compound is 3- (4-diethylamino-2-ethoxyphenyl) -3- ( 1-Ethyl-2-methylindol-3-yl) -4-azaphthalide

[0019]

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Further, according to the third thermoreversible recording material of the present invention, the thermoreversible recording material comprising a mixture containing an electron accepting compound, an electron donating coloring compound and a binder resin, The compound is 4-hydroxydocosananilide represented by the above formula (1), and the electron-donating color developing compound is 3,3-bis (1-n-butyl-2-methylindole represented by the following formula (4). -3- yl) Phthalide.

[0021]

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As described above, by making the electron-accepting compound and the electron-donating color-forming compound the constituent materials described above,
The thermal control allows color development and decoloration to occur as completely separate reactions, thus providing a practicable thermoreversible recording material. As the electron-accepting compound, besides 4-hydroxydocosananilide, 4-hydroxyhexadecaneanilide, 4-hydroxyoctadecaneanilide and
After synthesizing and comparing 4-hydroxyeicosananilide, 4-hydroxydocosanianilide was found to be the most suitable as a thermoreversible recording material in terms of reversibility, weather resistance (heat resistance and light resistance) and other aspects. Was. In addition, a comparative study of various materials as an electron-donating color-forming compound showed that 3-dibutylamino-6-yl-oxygen was found to be comprehensive in terms of color development, decolorability, reversibility, weather resistance (heat resistance and light resistance) and other properties. -Methyl-7
-Anilinofluoran, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindole-3-
It has been found that yl) -4-azaphthalide and 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide are most suitable as thermoreversible recording materials. By using these three types of electron-donating color-forming compounds individually, a thermoreversible recording material that exhibits one of black, blue, and red colors can be obtained.

In each thermoreversible recording material of the present invention, a color development / decoloration reaction occurs between the electron accepting compound and the electron donating color forming compound dispersed in the resin by heat control.
In other words, a chemical change occurs with the electron transfer by thermal control, and as a result, a color development / decoloration reaction occurs. At this time, the electron-accepting compound functions as a developer and the electron-donating color-forming compound functions as a dye. As a specific method of coloring and decoloring, a color is formed by rapid cooling after heating and is decolored by slow cooling after heating.

The principle of coloring and decoloring in the thermoreversible recording material of the present invention is considered as follows. When a colorless or pale-colored electron-donating color-forming compound is heated together with an electron-accepting compound, electron transfer from the electron-donating color-forming compound to the electron-accepting compound occurs, and the color develops. At this time, the electron-accepting compound is located very close to the dye molecule (electron-donating color-forming compound) that has developed color. On the other hand, when the electron accepting compound is separated from the colored dye molecule, the colored dye molecule receives an electron from the electron accepting compound again, and returns to the electron-donating color forming compound before coloring,
Decolorize.

Therefore, when the thermoreversible recording material is first heated to be in a molten state, the electron donating color-forming compound and the electron accepting compound are mixed, so that electron transfer occurs, and thus color is formed. When the mixture in the molten state is slowly cooled, the mixture is solidified while being phase-separated as the temperature is lowered, so that the electron-donating color-forming compound and the electron-accepting compound are separated from each other, and thus the color is erased. On the other hand, when the mixture in the molten state is quenched, it solidifies before phase separation occurs, so that the electron-donating color-forming compound keeps receiving electrons, that is, maintains the color-developing state.

In practicing the present invention, it is preferable that the mixing ratio of the electron-accepting compound to the electron-donating color-forming compound is a value within the range of 1 to 5. However,
The mixing ratio is the weight ratio, that is, the weight of the electron-accepting compound / the weight of the electron-donating color-forming compound. With such a mixing ratio, the thermoreversible recording material can easily form and erase an image by controlling thermal energy, and
It is a material that can be repeatedly performed, has good image contrast, and can maintain a stable image over time in an environment of daily life. More specifically, the thermoreversible recording material satisfies the evaluation criteria of a practical level relating to printing characteristics and the like.

In the present invention, preferably,
It is preferable that the binder resin is polyvinyl alcohol, the polyvinyl alcohol has a saponification degree within a range of 80 to 90 mole%, and the polymerization degree has a value within a range of 1,000 to 4,000. Polyvinyl alcohol is generally excellent in water solubility, dispersibility, film properties and thermal stability.
Also, in order to use polyvinyl alcohol as a binder resin, even when an appropriate solute is dissolved in polyvinyl alcohol, generally, the overall balance of solubility, solution viscosity, coating strength, hygroscopicity, and the like is excellent. . Further, by setting the value of the degree of saponification and the degree of polymerization within the above ranges, when the electron accepting compound and the electron donating color forming compound of the present invention are dissolved as a solute, a uniform and stable coating liquid, A thermoreversible recording material can be formed, and the electron accepting compound and the electron donating color forming compound do not precipitate or precipitate even when left for one month. Further, by applying this coating liquid, a uniform and stable coating film, that is, a thermoreversible recording layer can be formed, and even if recording / erasing is repeated, the electron accepting compound and the electron donating color forming compound are left on the surface. There is an advantage that it does not precipitate or clump inside.

According to the first thermoreversible recording medium of the present invention, a thermoreversible recording medium comprising a support and a first thermoreversible recording layer provided above the first main surface of the support is provided. In the recording medium, the first thermoreversible recording layer is composed of a mixture containing an electron-accepting compound, an electron-donating color-forming compound, and a binder resin. Is 4-hydroxydocosanianilide and the electron donating color-forming compound is 3-dibutylamino-6-methyl-7-anilinofluoran, the electron accepting compound is 4-hydroxydocosanianilide, and the electron The donor color-forming compound was converted to 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-
Ethyl-2-methylindol-3-yl) -4-azaphthalide, the electron-accepting compound is 4-hydroxydocosananilide, and the electron-donating color-forming compound is 3,3-bis.
(1-n-butyl-2-methylindol-3-yl) It is composed of at least one layer selected from the group consisting of layers to be phthalide.

By using a thermoreversible recording medium having such a configuration, it is possible to cause color development and decoloration to occur as completely separated reactions by thermal control. Become.

In the present invention, preferably,
The mixing ratio of the electron-accepting compound to the electron-donating color-forming compound is preferably a value within the range of 1 to 5.

By setting the mixing ratio as described above, the thermoreversible recording medium can easily and repeatedly form and erase an image by controlling the heat energy, and has a good image contrast. Thus, a stable image can be retained with time in an environment of daily life. More specifically, the thermoreversible recording medium satisfies the evaluation criteria of a practical level relating to the printing characteristics.

In the present invention, preferably,
It is preferable that the binder resin is polyvinyl alcohol, the polyvinyl alcohol has a saponification degree within a range of 80 to 90 mole%, and the polymerization degree has a value within a range of 1,000 to 4,000.

Further, in implementing the first thermoreversible recording medium of the present invention, the first thermoreversible recording layer may be a single layer. In the case of this configuration, regardless of whether the heating is performed from the support side or the first thermoreversible recording layer, depending on the type of the electron-donating coloring compound contained in the thermoreversible recording layer, black,
Any one of blue and red colors can be obtained.

In implementing the first thermoreversible recording medium, the first thermoreversible recording layer is formed as a laminate of two or three layers, and each layer constituting the laminate has a different electron donating coloration. Alternatively, the structure may be a layer containing a reactive compound. In the case of this configuration, by controlling the magnitude of the heat energy or changing the heating direction to the support side or the first thermoreversible recording layer side, any one of black, blue and red is used. Or a mixed color of two or more of black, blue and red can be obtained.

According to the second thermoreversible recording medium of the present invention, the support, the first thermoreversible recording layer provided above the first main surface of the support, (2) In a thermoreversible recording medium comprising a second thermoreversible recording layer provided above the main surface, the first thermoreversible recording layer and the second thermoreversible recording layer are composed of an electron accepting compound and an electron accepting compound. It consists of a mixture containing a donor color-forming compound and a binder resin, the electron-accepting compound is 4-hydroxydocosananilide, and the electron-donating color-forming compound is 3-dibutylamino-6-methyl-7-
The layer to be anilinofluoran, the electron-accepting compound to be 4-hydroxydocosananilide, and the electron-donating color-forming compound to be 3- (4-diethylamino-2-ethoxyphenyl) -3-
A layer comprising (1-ethyl-2-methylindol-3-yl) -4-azaphthalide; an electron-accepting compound comprising 4-hydroxydocosananilide; and an electron-donating color-forming compound comprising 3,3-
It comprises at least one thermoreversible recording layer selected from the group consisting of a layer of bis (1-n-butyl-2-methylindol-3-yl) phthalide.

By providing the thermoreversible recording layers on both sides of the support as in this configuration, the medium is heated to the first level.
By performing from the thermoreversible recording layer side or the second thermoreversible recording layer side, the color of black, blue and red is changed, or the color of black, blue and red is mixed. You can also get. Further, different images can be formed on both sides of the thermoreversible recording medium (so-called double-sided printing).

In the present invention, preferably,
The mixing ratio of the electron-accepting compound to the electron-donating color-forming compound is preferably a value within the range of 1 to 5.

In the present invention, preferably,
It is preferable that the binder resin is polyvinyl alcohol, the polyvinyl alcohol has a saponification degree within a range of 80 to 90 mole%, and the polymerization degree has a value within a range of 1,000 to 4,000.

In implementing the second thermoreversible recording medium of the present invention, each of the first thermoreversible recording layer and the second thermoreversible recording layer may be a single layer. At this time, if a transparent support is used, any one of black, blue, and red may be used depending on the type of the electron-donating color-forming compound contained in the thermoreversible recording layer on the heating direction side. One color can be obtained, and by heating from both sides,
Mixed colors can be obtained. When an opaque support is used, a single color image can be formed on both sides by performing heating from both sides (double-sided printing).

In implementing the second thermoreversible recording medium, the first thermoreversible recording layer and the second thermoreversible recording layer are each formed as a laminate of two or three layers. Each layer to be formed may be a layer containing the electron-donating color-forming compound different from each other. At this time, if a transparent support is used, a mixed color of three colors of black, blue and red can be obtained. When an opaque support is used as the support, it is also possible to form separate images of mixed colors on both sides of the thermoreversible recording medium by performing heating from both sides (double-sided printing).

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a thermoreversible recording material of the present invention and a thermoreversible recording medium using the same will be described below with reference to the drawings. In the drawings, the size, shape, and arrangement relationship of each component are only schematically shown to the extent that the present invention can be understood. It should also be understood that the materials used and numerical conditions described in the following examples are merely examples, and therefore, the present invention is not limited only to these materials and numerical conditions.
This embodiment will be described more specifically with reference to first to fifth examples.

(First Embodiment) In this embodiment, in the first thermoreversible recording material and the first thermoreversible recording medium,
Various mixing ratios of the electron-accepting compound and the electron-donating coloring compound (where the mixing ratio is a weight ratio, that is, the weight of the electron-accepting compound / the weight of the electron-donating coloring compound) A predetermined experiment described later was performed for the sample. That is, a first thermoreversible recording material and a first thermoreversible recording medium having a mixing ratio of 1.0 were prepared and an experiment was performed, and then the mixing ratio was 0.1, 0.5, 0.75, 2, 3, 4, and Various first thermoreversible recording materials and first thermoreversible recording media having different values of 5, 6, 7, 8, 9, and 10, respectively, were produced and experiments were performed.

First, examples of the first thermoreversible recording material of the present invention will be described.

The first thermoreversible recording material in this embodiment is composed of a mixture containing an electron-accepting compound, an electron-donating color-forming compound and a binder resin. And
The electron-accepting compound is 4-hydroxydocosananilide, and the electron-donating color-forming compound is 3-dibutylamino-6
-Methyl-7-anilinofluoran. The binder resin is polyvinyl alcohol. The polyvinyl alcohol has a degree of saponification of 88 mole% and a degree of polymerization of 3,500.

Since the first thermoreversible recording material uses 3-dibutylamino-6-methyl-7-anilinofluoran as the electron-donating color-forming compound, it exhibits a black color when colored. At this time, by setting the mixing ratio of the electron-accepting compound and the electron-donating color-forming compound to an appropriate value in the range of 1 to 5, as is clear from the experimental results described later,
The first thermoreversible recording material satisfies evaluation criteria such as printing characteristics.

Next, an embodiment of a first thermoreversible recording medium provided with a thermoreversible recording layer composed of the first thermoreversible recording material of this embodiment will be described. FIG. 1 is a sectional view schematically showing the configuration of the first thermoreversible recording medium of this embodiment.

The first thermoreversible recording medium of this embodiment is:
It comprises a support 10 and a first thermoreversible recording layer 12 provided above the main surface of the support. The first thermoreversible recording layer 12 is made of a mixture containing an electron-accepting compound, an electron-donating color-forming compound, and a binder resin. The electron-accepting compound is 4-hydroxydocosananilide, and the electron-donating color-forming compound is 3-dibutylamino-6-methyl.
-7- Anilinofluoran. The binder resin is polyvinyl alcohol, and the polyvinyl alcohol has a degree of saponification of 88 mole% and a degree of polymerization of 3500.
The first thermoreversible recording layer 12 is a single layer.

In the configuration example shown in FIG. 1, a resin layer 14, an ultraviolet absorbing layer 16 and a protective layer 18 are further provided on the first thermoreversible recording layer 12 in this order.

In the first thermoreversible recording medium having this structure, the mixing ratio of the electron-accepting compound to the electron-donating color-forming compound is 1
By setting an appropriate value within the range from 1 to 5, the first thermoreversible recording medium that satisfies the evaluation criteria such as the printing characteristics can be obtained, as is clear from the experimental results described later.

Next, the first thermoreversible recording material of the first embodiment and a method for manufacturing a first thermoreversible recording medium using the same will be described below.

First, the first thermoreversible recording layer 12 was placed on the support 10
Various liquids are prepared in order to adjust a coating liquid to be formed thereon.

First, a polyvinyl alcohol solution is prepared as a binder resin. PVA235 manufactured by Kuraray Co., Ltd. was used as the polyvinyl alcohol. After dissolving 80 parts by weight of this polyvinyl alcohol in 1920 parts by weight of pure water while heating for 3 hours, the mixture is cooled to room temperature to obtain a polyvinyl alcohol solution.

Next, 4-hydroxydocosananilide was prepared as an electron-accepting compound, and 100 parts by weight of 4-hydroxydocosanianilide and 1000 parts of the above polyvinyl alcohol solution were prepared.
Parts by weight, and then pulverized and dispersed in a ball mill for 144 hours to prepare a liquid 1A.

Next, 3-dibutylamino-6-methyl-7-anilinofluoran was prepared as an electron-donating color-forming compound, and 100 parts by weight of 3-dibutylamino-6-methyl-7-anilinofluoran was prepared. And 1 part by weight of the above polyvinyl alcohol solution, and then pulverized and dispersed in a ball mill for 96 hours to prepare a liquid 1B.

Next, the first thermoreversible recording material can be prepared by mixing the above prepared liquid 1A and liquid 1B, and this is used as a coating liquid. The mixing ratio of the electron-accepting compound 4-hydroxydocosaneanilide and the electron-donating color-forming compound 3-dibutylamino-6-methyl-7-anilinofluoran in the coating solution (electron-accepting compound Weight / weight of the electron donating coloring compound) is 1.0. By changing the weight part of the electron-accepting compound in the liquid 1A or the weight part of the electron-donating color-forming compound in the liquid 1B, various coating liquids having different mixing ratios can be obtained.

In this embodiment, as the thermoreversible recording material constituting the first thermoreversible recording layer 12, an electron accepting compound,
Although a mixture of only the electron-donating color-forming compound and the binder resin was used, other materials may also be mixed as long as they have a function of improving the properties of the first thermoreversible recording layer 12.

Next, as the support 10, for example,
Prepare a 0 μm white PET film. Next, the support 10
Dry the above coating solution with a bar coater to a thickness of 5 μm.
Apply so that This is dried by heating with a circulating hot air dryer at a temperature of 60 ° C. for 3 minutes to form a first thermoreversible recording layer 12 on the support 10.

Next, a resin layer 14 is formed on the first thermoreversible recording layer 12.
To form Polyvinyl alcohol (Kuraray PV)
A235) 40 parts by weight are dissolved in 960 parts by weight of pure water while heating for 3 hours, and then cooled to room temperature to obtain a coating solution. This coating solution is applied on the first thermoreversible recording layer 12 by a bar coater so that the dry film thickness becomes 1 μm. This is dried by heating in a circulating hot air dryer at a temperature of 60 ° C for 3 minutes.
A resin layer is formed on the thermoreversible recording layer 12.

Next, an ultraviolet absorbing layer 16 is formed on the resin layer 14. A coating solution is prepared by dissolving 600 parts by weight of an ultraviolet absorbent (UVA935LH) manufactured by BASF Corporation in 450 parts by weight of tetrahydrofuran and 150 parts by weight of toluene. This coating solution is applied to a resin layer using a bar coater so that the dry film thickness becomes 1 μm.
14 Apply on top. This is circulated in a hot air dryer at a temperature of 80 ° C.
After drying by heating for 3 minutes, the ultraviolet absorbing layer 16
To form

Next, a protective layer 18 is formed on the ultraviolet absorbing layer 16. A coating liquid is prepared by dissolving 335 parts by weight of a hard coat agent (C7-157) manufactured by Dainippon Ink and Chemicals, Inc. in 165 parts by weight of thinner (# 024) manufactured by Dainippon Ink and Chemicals, Inc. This coating solution is applied on the ultraviolet absorbing layer 16 by a bar coater so that the film thickness after drying and curing becomes 3 μm.
This is heated and dried at a temperature of 60 ° C. for 1 minute by a circulating hot air dryer, and then cured by irradiation with a UV lamp to form a protective layer 18 on the ultraviolet absorbing layer 16.

As described above, the first thermoreversible recording layer 12, the resin layer 14, the ultraviolet absorbing layer 16 and the protective layer 18 are formed on the support 10.
Are sequentially formed to obtain a first thermoreversible recording medium. This medium is referred to as AR1.

In this embodiment, the AR1 having a mixing ratio of the electron-accepting compound to the electron-donating color-forming compound of 1.0 was used.
Other than the above, various first thermoreversible recording materials having different mixing ratios in the range of 0.1 to 10 and different values, respectively, and first thermoreversible recording media using the same were produced by the above method. .

Next, a method for measuring various properties of the first thermoreversible recording material obtained by the above-described manufacturing method and the first thermoreversible recording medium using the same will be described below. . In the static characteristics, the general characteristics of color development and decoloration are measured by heating using a hot plate. In the printing characteristics, the printing characteristics are measured using an actual thermal printing device. For image storability, heat resistance and light resistance of a sample printed using a thermal printing apparatus are measured.

Measurement method 1. Static characteristics Heat on a hot plate at a predetermined temperature (140 ° C.) for 1 minute, and then rapidly cool to room temperature. As a quenching method, water is prepared in a container (for example, a beaker), and a sample is quickly immersed in water with tweezers from a hot plate. At this time, the water temperature is, for example, 15 to 25 ° C. Thereafter, the optical density (OD) of the colored state is measured at room temperature using a Macbeth densitometer. Next, at a predetermined temperature (150 ° C) on a hot plate,
Heat for 1 minute, then slowly cool down to room temperature (natural cooling), and then measure the optical density (OD) in the decolored state with a Macbeth densitometer at room temperature. Here, the optical density means the reflection density, and is defined as OD = log (100 / R) where R (%) is the reflectance. When R = 100 (%), OD = 0, and when R = 1 (%), OD = 2.
Becomes larger. When comparing the temperatures during quenching and slow cooling, there is no significant difference between the temperature of water and air.However, since water has a higher thermal conductivity than air, it is cooled at a rate greater than 50 ° C / s in water. , And therefore considered to be quenched, in air at 50 ° C
It is believed that it cools at a rate less than / s and therefore slows down.

2. Printing Characteristics A thermoreversible recording medium is cut into a card size, and a test pattern is printed using a rewritable card reader / writer (RC-20) manufactured by Oki Electric Industry Co., Ltd. In this case, heating on the pulse by the thermal head results in rapid cooling, and no rapid cooling means is required. Measure the optical density (OD) of the printed area at room temperature with a Macbeth densitometer. Next, the entire print sample is erased by a heat roller heated to 150 ° C. In this case, natural cooling to room temperature results in slow cooling. At room temperature, the optical density (OD) of the erased part is measured with a Macbeth densitometer.

3. Image preservability 1) Heat resistance at room temperature: A print sample prepared in the same manner as the above print characteristics is allowed to stand at room temperature for 30 days, and then the optical density (OD) is measured with a Macbeth densitometer. 2) High temperature heat resistance: A print sample prepared in the same manner as the above print characteristics is left at 40 ° C. for 24 hours, and then the optical density (OD) is measured with a Macbeth densitometer. 3) Indoor light fastness: After a print sample prepared in the same manner as the above print characteristics is left under a fluorescent lamp for 30 days, the optical density (OD) is measured with a Macbeth densitometer. 4) Outdoor light resistance: A print sample prepared in the same manner as the above print characteristics is allowed to stand outdoors (under sunlight) for one day, and then the optical density (OD) is measured with a Macbeth densitometer.

The principle of image formation and erasing in the thermoreversible recording material of the present invention is a reversible chemical reaction between an electron-donating color-forming compound and an electron-accepting compound and a reversible microstructure change. It can be presumed that the characteristics are greatly affected by the types and mixing ratios of the electron-donating color-forming compound and the electron-accepting compound used.

The object of the present invention is to form and erase an image with low printing energy (a normal thermal printing device can be used), and to obtain a high contrast (the same level as a printed matter obtained by a normal printer). In order to obtain a thermoreversible recording material having heat resistance and light resistance (which can be repeatedly used in an indoor environment) and a thermoreversible recording medium using the same, the following properties were measured for Evaluation criteria were set, and a mixture ratio that cleared all the evaluation criteria was found.

Evaluation Criteria 1. Static characteristics 1) Coloring state; OD ≧ 1.4 after heating and quenching at 140 ° C 2) Decoloring state; OD ≦ 0.2 after heating and gradual cooling at 150 ° C 3) Repetition; After 100 repetitions of (decolorization), the color development state OD ≧ 1.2 and the colorless state OD ≦ 0.3

2. Printing characteristics 1) Printing part; OD ≧ 1.2 2) Erasing part; OD ≦ 0.2 3) Repeat; After repeating printing / erasing 100 times Printing part OD ≧ 1.0, Erased part OD ≦ 0.3.

3. Image storability 1) Heat resistance at room temperature: printing part: OD ≧ 1.2, non-printing part: OD ≦ 0.
2. Storage rate (OD 30 days after printing / initial OD of printing) ≧ 0.
9 2) High temperature heat resistance: printed area: OD ≧ 1.0, non-printed area: OD ≦ 0.
2, Storage rate (OD 24 hours after printing / initial OD of printing) ≧
0.6 3) Indoor light resistance: printed area: OD ≧ 1.2, non-printed area: OD ≦ 0.
2 4) Outdoor light resistance: printed area: OD ≧ 1.2, non-printed area: OD ≦ 0.
Four .

Measurement Results First, AR1 having a mixing ratio of 1.0 was measured. AR1
Was measured for measurement items slightly different from the evaluation criteria described above.

1. Static characteristics 1) Colored state; OD ≧ 1.4 2) Decolored state; OD ≦ 0.2 3) Colored state after repeating the colored state and decolored state 100 times
OD ≧ 1.4 and decolored state OD ≦ 0.2 were obtained with good reproducibility.

2. Printing characteristics 1) Printed part OD = 1.0-1.2, non-printed part OD = 0.1-0.2, contrast (printed part OD / non-printed part OD) = 8-10, equivalent to or higher than printed matter obtained by ordinary printer Was checked for contrast. 2) In the erasing section (erasing with a heat roller), OD ≦ 0.2
Was obtained, and the print pattern was completely erased.

3. Image storability 1) Heat resistance at room temperature: printing part: OD = 1.0 to 1.2, non-printing part: OD
= 0.1-0.2 ΔOD (| initial OD−OD after 30 days |) <0.1 Both the printed portion and the non-printed portion hardly changed even after standing for 30 days. 2) High temperature heat resistance: The non-printed portion hardly changed.
Although a slight decrease in OD was observed in the printed portion, an image preservation ratio (OD after 24 hours of the printed portion / initial OD of the printed portion) ≧ 0.6 was obtained. 3) Indoor light resistance: printed part; OD = 1.0 to 1.2, non-printed part: OD
= 0.1-0.2 ΔOD (| initial OD−OD after 30 days) <0.1 was obtained, and hardly changed. 4) Outdoor light fastness: OD was slightly increased in non-printed areas, but OD ≦ 0.4 was maintained.

As described above, the AR1 can form and erase an image with low printing energy (a normal thermal printing device can be used), and has a high contrast (the same level as a printed matter obtained with a normal printer). ) And heat resistance and light resistance (which can be repeatedly used in an indoor environment).

Next, with respect to various first thermoreversible recording materials having different mixing ratios in the range of 0.1 to 10 and different values, respectively, and first thermoreversible recording media using the same,
The measurement was performed according to the above evaluation criteria.

In the static characteristics, a favorable tendency was observed in which the higher the mixing ratio, the higher the OD in the colored state. However, there was a saturation region of OD with an increase in the mixing ratio, and when the mixing ratio was larger than 5, the OD tended to decrease. When the mixing ratio was less than 1, sufficient color density could not be obtained. Similarly, with respect to the printing characteristics, when the mixture ratio was increased, a favorable tendency was observed in which the OD of the printed portion was increased. However, there was a saturation region of the OD, and when the mixture ratio was greater than 5, the OD tended to decrease. The saturation region of OD was different from the saturation region in the case of static characteristics. When the mixing ratio was less than 1, sufficient color density could not be obtained, and erasure remained easily. Regarding the image storability, there was a favorable tendency that the heat resistance was improved as the mixing ratio was increased.

From the above test results, the first thermoreversible recording material which can satisfy all the above evaluation criteria and the first thermoreversible recording medium using the same have a mixing ratio within the range of 1 to 5. Was found to be the value of.

Comparative Example The printing characteristics of a reversible recording material in which an organic low-molecular substance was dispersed in a resin binder disclosed in Reference 1 (Japanese Patent Application Laid-Open No. 63-39377) were measured in the same manner as in the first example. Was measured by optical density (OD). According to this configuration, the reversible recording layer made of the reversible recording material is formed on the support. At this time, transparent PET as a support
Was measured on a black standard plate. Since the printed portion becomes cloudy, the image is printed in white (cloudy) on a black background.

As a result, a printed portion; OD = 0.5 to 0.8, and a non-printed portion: OD = 1.0 to 1.3 were obtained.

The printing characteristics of the reversible thermosensitive recording medium using the color-reducing agent disclosed in Reference 3 (Japanese Patent Laid-Open No. 2-188293)
The optical density (OD) was measured in the same manner as in the examples.
According to this configuration, the reversible thermosensitive recording layer composed of the reversible thermosensitive recording material is formed on the support. At this time, white PET was used as a support. Since the printing portion is colored, black (colored) printing is performed on a white background.

As a result, a printed portion: OD = 0.7 to 0.9, and a non-printed portion: OD = 0.2 to 0.4 were obtained.

Both printing characteristics are the same as those in the first embodiment.
The contrast (printed portion OD / non-printed portion OD) of AR1 was significantly inferior to 8 to 10, and the first thermoreversible recording material of the first embodiment of the present invention and the first thermoreversible recording material using the same were used. It can be seen that the contrast of the reversible recording medium is excellent.

(Second Embodiment) In this embodiment, in the second thermoreversible recording material and the first thermoreversible recording medium,
For various compounds having different mixing ratios of the electron-accepting compound and the electron-donating color-forming compound, predetermined experiments described below were performed. That is, a second thermoreversible recording material and a first thermoreversible recording medium having a mixing ratio of 1.0 were prepared, and after performing experiments, the mixing ratio was 0.1, 0.5, 0.75, 2, 3, 4, and Various second thermoreversible recording materials and first thermoreversible recording media having different values of 5, 6, 7, 8, 9, and 10, respectively, were produced and experiments were performed.

First, examples of the second thermoreversible recording material of the present invention will be described.

The second thermoreversible recording material in this embodiment is composed of a mixture containing an electron-accepting compound, an electron-donating color-forming compound and a binder resin. And
The electron-accepting compound is 4-hydroxydocosananilide, and the electron-donating color-forming compound is 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl ) -4-Azaphthalide. The binder resin is polyvinyl alcohol. The polyvinyl alcohol has a degree of saponification of 88 mole% and a degree of polymerization of 3,500.

In the second thermoreversible recording material, an electron-donating color-forming compound is converted to 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindole-3-yl )-
Because it is 4-azaphthalide, it shows a blue color when developed. At this time, by setting the mixing ratio of the electron-accepting compound and the electron-donating color-forming compound to an appropriate value in the range of 1 to 5, as is clear from the experimental results described later,
The second thermoreversible recording material satisfies evaluation criteria such as printing characteristics.

Next, an embodiment of a first thermoreversible recording medium provided with a thermoreversible recording layer composed of the second thermoreversible recording material of this embodiment will be described. The configuration of this embodiment is the same as that of FIG. 1 except for the constituent materials of the first thermoreversible recording layer, and thus the illustration is omitted. The first thermoreversible recording medium of this embodiment includes a support and a first thermoreversible recording layer provided above the main surface of the support. The first thermoreversible recording layer is composed of a mixture containing an electron-accepting compound, an electron-donating color-forming compound and a binder resin. The electron-accepting compound is 4-hydroxydocosananilide, and the electron-donating color-forming compound is 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindole-3. -Il) -4-azaphthalide. The binder resin is polyvinyl alcohol, the polyvinyl alcohol has a degree of saponification of 88 mole%, and the degree of polymerization is
3500. The first thermoreversible recording layer is a single layer.

The first thermoreversible recording medium of this configuration has a mixing ratio of the electron-accepting compound to the electron-donating color-forming compound of 1
By setting an appropriate value within the range from 1 to 5, the first thermoreversible recording medium that satisfies the evaluation criteria such as the printing characteristics can be obtained, as is clear from the experimental results described later.

The second thermoreversible recording material of the second embodiment and the method for producing the first thermoreversible recording medium using the same are described in the following, when the electron-donating color-forming compound is 3- (4-diethylamino-2). -Ethoxyphenyl) -3- (1-ethyl-2-methylindole-3-
Except that it is yl) -4-azaphthalide, the structure and manufacturing method of the first embodiment are the same. The mixing ratio obtained at this time is 1.
The first thermoreversible recording medium of No. 0 is designated as BR1.

By changing the mixing ratio of the electron-accepting compound and the electron-donating color-forming compound in the same manner as in the first embodiment, the mixing ratio is in the range of 0.1 to 10, Various second thermoreversible recording materials having different values and first thermoreversible recording media using the same were produced.

First, BR1 was measured in the same manner as AR1, and it was found that images could be formed and erased with low printing energy (a normal thermal printing device could be used) and high contrast (normal printers). And the heat resistance and light resistance (which can be repeatedly used in an indoor environment) were obtained.

Next, the mixing ratio obtained by the above-described manufacturing method was 0.1%.
The various thermoreversible recording materials and the first thermoreversible recording media using the same having different values within the range from 1 to 10 were measured by the measurement method shown in the first embodiment. Was measured. As a result, it has been found that a medium that can satisfy all the evaluation criteria shown in the first embodiment is when the mixture ratio is a value within the range of 1 to 5.

(Third Embodiment) In this embodiment, in the third thermoreversible recording material and the first thermoreversible recording medium,
For various compounds having different mixing ratios of the electron-accepting compound and the electron-donating color-forming compound, predetermined experiments described below were performed. That is, a third thermoreversible recording material and a first thermoreversible recording medium having a mixing ratio of 1.0 were prepared and an experiment was performed, and then the mixing ratio was 0.1, 0.5, 0.75, 2, 3, 4, and Various third thermoreversible recording materials and first thermoreversible recording media having different values of 5, 6, 7, 8, 9, and 10, respectively, were produced and subjected to experiments.

First, examples of the third thermoreversible recording material of the present invention will be described.

The third thermoreversible recording material in this embodiment is composed of a mixture containing an electron-accepting compound, an electron-donating color-forming compound and a binder resin. And
The electron-accepting compound is 4-hydroxydocosananilide, and the electron-donating color-forming compound is 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide. The binder resin is polyvinyl alcohol. The polyvinyl alcohol has a degree of saponification of 88 mole% and a degree of polymerization of 3,500.

This third thermoreversible recording material uses 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide as the electron-donating color-forming compound. It has a red color. At this time, by setting the mixing ratio between the electron-accepting compound and the electron-donating color-forming compound to an appropriate value within the range of 1 to 5, the printing characteristics and the like can be clearly understood from the experimental results described later. A third thermoreversible recording material that satisfies the evaluation criteria.

Next, an embodiment of a first thermoreversible recording medium provided with a thermoreversible recording layer composed of the third thermoreversible recording material of this embodiment will be described. The configuration of this embodiment is the same as that of FIG. 1 except for the constituent materials of the first thermoreversible recording layer, and thus the illustration is omitted. The first thermoreversible recording medium of this embodiment includes a support and a first thermoreversible recording layer provided above the main surface of the support. The first thermoreversible recording layer is composed of a mixture containing an electron-accepting compound, an electron-donating color-forming compound and a binder resin. Then, the electron-accepting compound is 4-hydroxydocosananilide, and the electron-donating coloring compound is 3,3-bis (1-n-
Butyl-2-methylindol-3-yl) phthalide. The binder resin is polyvinyl alcohol,
Polyvinyl alcohol has a degree of saponification of 88 mole% and a degree of polymerization of 3500. The first thermoreversible recording layer is a single layer.

In the first thermoreversible recording medium having this configuration, the mixing ratio of the electron-accepting compound to the electron-donating color-forming compound is 1
By setting an appropriate value within the range from 1 to 5, the first thermoreversible recording medium that satisfies the evaluation criteria such as the printing characteristics can be obtained, as is clear from the experimental results described later.

The third thermoreversible recording material of the third embodiment and the method for producing the first thermoreversible recording medium using the same are described in the case where the electron-donating color-forming compound is 3,3-bis (1- The structure and manufacturing method of the first embodiment are the same as those of the first embodiment except that n-butyl-2-methylindol-3-yl) phthalide is used. This is referred to as a first thermoreversible recording medium CR1 having a mixing ratio of 1.0 obtained at this time.

By changing the mixing ratio between the electron-accepting compound and the electron-donating color-forming compound in the same manner as in the first embodiment, the mixing ratio is in the range of 0.1 to 10, Various third thermoreversible recording materials having different values and first thermoreversible recording media using the same were produced.

First, when the same measurement as that of AR1 was performed for CR1, it was possible to form and erase an image with low printing energy (a normal thermal printing device can be used), and to obtain a high contrast (normal printer). And the heat resistance and light resistance (which can be repeatedly used in an indoor environment) were obtained.

Next, the mixing ratio obtained by the above-described manufacturing method was 0.1%.
The characteristics of various third thermoreversible recording materials having different values in the range from 1 to 10 and the first thermoreversible recording medium using the same were measured by the measurement method described in the first embodiment. Was measured. As a result, it has been found that a medium that can satisfy all the evaluation criteria shown in the first embodiment is when the mixture ratio is a value within the range of 1 to 5.

(Fourth Embodiment) Next, an application example of the first thermoreversible recording medium described in the first to third embodiments will be described.

FIG. 2 is a sectional view showing the structure of the first thermoreversible recording medium of the fourth embodiment. In the first to third embodiments, the first thermoreversible recording medium has a structure in which the first thermoreversible recording layer is a single layer. First of Fourth Embodiment
In the thermoreversible recording medium described above, the first thermoreversible recording layer 23 has a two-layered structure, and the layers constituting the two-layered structure are layers containing mutually different electron-donating color-forming compounds. It has become. The first thermoreversible recording layer 23 includes first to third
It is made of the thermoreversible recording material described in the examples, and the mixing ratio between the electron-accepting compound and the electron-donating color-forming compound is, for example, 1.0. The binder resin is polyvinyl alcohol, and the polyvinyl alcohol has a degree of saponification.
It is 88 mole% and the degree of polymerization is 3500.

According to this structure, the first thermoreversible recording layer a22 and the first thermoreversible recording layer b24 are sequentially provided on the support 20. Similarly,
The structure is such that a resin layer 26, an ultraviolet absorbing layer 28 and a protective layer 30 are sequentially provided.

At this time, for example, the first thermoreversible recording layer a22
Is the first thermoreversible recording layer a22 that emits red color used in the third embodiment, and the first thermoreversible recording layer b24 is the first thermoreversible recording layer b24 that emits blue color used in the second embodiment. And If heat energy is applied from the first thermoreversible recording layer b24 side so that only the first thermoreversible recording layer b24 is colored, a blue color is obtained. Further increase the applied heat energy,
By coloring the first thermoreversible recording layer a22 and the first thermoreversible recording layer b24, a mixed color of red and blue (close to black) can be obtained. Further, if heat energy is applied from the support 20 side so that only the first thermoreversible recording layer a22 is colored,
A red color is obtained.

In this embodiment, the first thermoreversible recording layer a22
The first thermoreversible recording layer b24 is made of a thermoreversible recording material that emits red and blue, respectively. However, the order may be reversed, and the thermoreversible recording layer that emits black used in the first embodiment may be used. Materials may be used. Further, the first thermoreversible recording layer may have a structure in which three layers are used instead of two layers, and all thermoreversible recording materials used in the first to third embodiments are used in three layers.

(Fifth Embodiment) Next, an embodiment of the second thermoreversible recording medium will be described.

FIG. 3 is a sectional view showing the structure of the second thermoreversible recording medium of the fifth embodiment. In the second thermoreversible recording medium of the fifth embodiment, a support 40, a first thermoreversible recording layer 42 provided above a first main surface of the support 40,
40 second thermoreversible recording layer provided above the second main surface
It is equipped with 50. The first thermoreversible recording layer 42 and the second thermoreversible recording layer 50 are made of a mixture containing an electron-accepting compound, an electron-donating color-forming compound, and a binder resin. The first thermoreversible recording layer 42 and the second thermoreversible recording layer 50 are made of 4-hydroxydocosananilide as the electron accepting compound and 3-dibutylamino-6-methyl as the electron donating color former. -7- Anilinofluoran layer, the electron-accepting compound is 4-hydroxydocosananilide, and the electron-donating color-forming compound is 3- (4-diethylamino-2-ethoxyphenyl) -3- (1- Ethyl-2-methylindole-3-
Yl) -4-azaphthalide, the electron-accepting compound is 4-hydroxydocosananilide, and the electron-donating coloring compound is 3,3-bis (1-n-butyl-2-methylindole-3). -Yl) at least one layer selected from the group consisting of layers to be phthalide. The mixing ratio between the electron-accepting compound and the electron-donating color-forming compound is, for example, 1.0. The binder resin is polyvinyl alcohol. The polyvinyl alcohol has a degree of saponification of 88 mole% and a degree of polymerization of 3,500. Further, the first thermoreversible recording layer 42 and the second thermoreversible recording layer 50 have a single-layer structure.

In this structure, the first thermoreversible recording layer 42 is sequentially provided with the first thermoreversible recording layer 42 in the same manner as in the first to third embodiments.
A resin layer 44, a first ultraviolet absorbing layer 46 and a first protective layer 48 are provided, and a second resin layer is sequentially formed on the second thermoreversible recording layer 50.
52, a second ultraviolet absorbing layer 54 and a second protective layer 56 are provided.

At this time, for example, the first thermoreversible recording layer 42, which emits red light used in the third embodiment, is used as the first thermoreversible recording layer 42.
42, the second thermoreversible recording layer 50 is the second thermoreversible recording layer 50 that emits blue color used in the second embodiment, and the support 40 is transparent PET. When heat energy is applied from the first thermoreversible recording layer 42 side, a red color is obtained, and when heat energy is applied from the second thermoreversible recording layer 50 side, a blue color is obtained. First thermoreversible recording layer 42 and second thermoreversible recording layer
If heat energy is applied from both sides of the 50, a mixed color of red and blue (close to black) can be obtained.

In the above example, if the support 40 is made of white PET, by applying heat energy from both sides of the first thermoreversible recording layer 42 and the second thermoreversible recording layer 50,
Color development of different images and characters is obtained as a single color on both sides, and double-sided printing is possible.

In this embodiment, the first thermoreversible recording layer 42 and the second thermoreversible recording layer 50 are single layers, but two layers of the first thermoreversible recording layer are provided above the first main surface. A structure in which a single layer of the second thermoreversible recording layer 50 is provided above the layer 42 and the second main surface, and all the thermoreversible recording materials used in the first to third embodiments are used for these three layers. It is good.

Further, the first thermoreversible recording layer 42 and the second thermoreversible recording layer 50 are each formed as a laminate of two or three layers, and each layer constituting each laminate has a different electron donating property. It may be a layer containing a coloring compound. At this time, if the support 40 is made of white PET, a mixed color of different images and characters is obtained on both sides of the first thermoreversible recording layer 42 and the second thermoreversible recording layer 50, respectively. Becomes possible.

The above-mentioned conditions such as numerical values, shapes and materials are merely examples. Therefore, the present invention is not limited to this embodiment.

For example, in the thermoreversible recording medium according to the embodiment of the present invention, polyethylene terephthalate (PET) is used as a constituent material of the support, but polyethylene, polyvinyl chloride, polystyrene, polycarbonate, polyarylate, or synthetic resin is used. Paper may be used.

As the constituent material of the protective layer, a UV-curable resin containing polyepoxy acrylate as a main component was used, but other UV-curable resins, polyester, polyvinyl chloride, polyolefin, polyvinyl alcohol, polystyrene, polyamide, polycarbonate , Polyarylate, fluororesin, polyacrylonitrile, etc., or inorganic substances, such as SiO ₂ , TiO ₂ , Al ₂ O ₃ .

Examples of the use of the thermoreversible recording medium material of the present invention and the thermoreversible recording medium using the same include cards, paper, OHP sheets, displays and the like.

[0121]

As is apparent from the above description, according to the present invention, a thermoreversible recording material comprising an electron-accepting compound, an electron-donating color-forming compound and a binder resin has an electron-accepting compound. Is 4-hydroxydocosananilide, and the electron-donating color-forming compound is 3-dibutylamino-6-methyl-7-anilinofluoran, 3- (4-diethylamino-2-ethoxyphenyl) -3- ( 1-ethyl-2-methylindol-3-yl) -4-azaphthalide and 3,3-bis (1
-n-butyl-2-methylindol-3-yl) phthalide, which makes it possible to cause color development and decoloration as completely separated reactions by thermal control, and It becomes a possible thermoreversible recording material. Further, in a thermoreversible recording medium comprising a support and a first thermoreversible recording layer provided above the first main surface of the support, the first thermoreversible recording layer has the aforementioned thermoreversible recording layer. Since the recording medium is composed of a recording material, it is possible to cause color development and decolorization as completely separated reactions by thermal control, and thus a practicable thermoreversible recording medium.

Further, when the mixing ratio of the electron-accepting compound to the electron-donating color-forming compound is set to a value within the range of 1 to 5, the formation and erasing of an image can be easily performed by controlling the heat energy. In addition, it is possible to provide a thermoreversible recording material and a thermoreversible recording medium using the same, which can be repeatedly performed, have a good image contrast, and can maintain a stable image over time in an environment of daily life. In other words, in order to realize an inexpensive and large image display, images can be formed and erased with low printing energy (a normal thermal printing device can be used), and a high contrast (normal printer) can be used. And the same level of heat and light resistance (can be used repeatedly in an indoor environment)
And a thermoreversible recording medium using the same.

Further, the thermoreversible recording medium is placed on the first support.
By providing a structure in which a thermoreversible recording layer composed of two or more layers emitting different colors is provided on the upper side of the main surface, not only a single color but also a mixed color image can be formed or erased.

Further, the thermoreversible recording medium is placed on the first support.
By adopting a structure in which a thermoreversible recording layer is provided on each of the main surface and the second main surface, not only a single color but also a mixed color image can be formed or erased, and further, the first main surface and the second main surface can be formed. Different images can be separately formed or erased on both sides of the surface.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first thermoreversible recording medium of a first embodiment.

FIG. 2 is a diagram illustrating a configuration of a first thermoreversible recording medium of a fourth embodiment.

FIG. 3 is a diagram showing a configuration of a second thermoreversible recording medium of a fifth embodiment.

[Explanation of symbols]

 10: support 12: first thermoreversible recording layer 14: resin layer 16: ultraviolet absorbing layer 18: protective layer 20: support 22: first thermoreversible recording layer a 23: first thermoreversible recording layer 24 : First thermoreversible recording layer b 26: resin layer 28: ultraviolet absorbing layer 30: protective layer 40: support 42: first thermoreversible recording layer 44: first resin layer 46: first ultraviolet absorbing layer 48: First protective layer 50: Second thermoreversible recording layer 52: Second resin layer 54: Second ultraviolet absorbing layer 56: Second protective layer

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B41M 5/18 111

Claims (15)

[Claims] 1. A thermoreversible recording material comprising a mixture containing an electron-accepting compound, an electron-donating color-forming compound and a binder resin, wherein the electron-accepting compound is 4-hydroxydocosananilide, and A thermoreversible recording material, characterized in that the donative coloring compound is 3-dibutylamino-6-methyl-7-anilinofluoran. 2. A thermoreversible recording material comprising a mixture containing an electron-accepting compound, an electron-donating color-forming compound and a binder resin, wherein the electron-accepting compound is 4-hydroxydocosananilide, and Thermoreversible characterized in that the donor color-forming compound is 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide Recording material. 3. A thermoreversible recording material comprising a mixture containing an electron-accepting compound, an electron-donating color-forming compound and a binder resin, wherein the electron-accepting compound is 4-hydroxydocosananilide, and The donor color-forming compound is 3,3-bis (1
-n-butyl-2-methylindol-3-yl) phthalide; a thermoreversible recording material. 4. The thermoreversible recording material according to claim 1, wherein a mixing ratio of the electron-accepting compound to the electron-donating color-forming compound is in a range from 1 to 5. Wherein the mixing ratio is the weight of the electron-accepting compound / the weight of the electron-donating color-forming compound. 5. The thermoreversible recording material according to claim 1, wherein the binder resin is polyvinyl alcohol, and the polyvinyl alcohol has a saponification degree of 80 to 90 mole%.
%, And the degree of polymerization is from 1000 to 40%.
A thermoreversible recording material having a value within the range up to 00. 6. A thermoreversible recording medium comprising a support and a first thermoreversible recording layer provided above a first main surface of the support, wherein the first thermoreversible recording layer is A mixture containing an electron-accepting compound, an electron-donating color-forming compound, and a binder resin, wherein the first thermoreversible recording layer comprises the electron-accepting compound as 4-hydroxydocosananilide and the electron-donating compound. A layer in which the color-forming compound is 3-dibutylamino-6-methyl-7-anilinofluoran; the electron-accepting compound is 4-hydroxydocosananilide; and the electron-donating color-forming compound is 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, and the electron-accepting compound is 4-hydroxydocosananilide; and 3,3-bis ( 1-n-butyl-2-methylindol-3-yl) A thermoreversible recording medium comprising at least one layer selected from the group consisting of layers to be phthalide. 7. The thermoreversible recording medium according to claim 6, wherein a mixing ratio of the electron accepting compound and the electron donating color forming compound is a value within a range from 1 to 5. A thermoreversible recording medium, wherein the ratio is the weight of the electron-accepting compound / the weight of the electron-donating color-forming compound. 8. The thermoreversible recording medium according to claim 6, wherein the binder resin is polyvinyl alcohol, and the polyvinyl alcohol has a degree of saponification of from 80 mol% to 90 mol.
%, And the degree of polymerization is from 1000 to 40%.
A thermoreversible recording medium having a value in the range up to 00. 9. The thermoreversible recording medium according to claim 6, wherein the first thermoreversible recording layer is a single layer. 10. The thermoreversible recording medium according to claim 6, wherein the first thermoreversible recording layer is a laminate of two or three layers,
A thermoreversible recording medium, wherein each layer constituting the laminate is a layer containing the electron-donating color-forming compound different from each other. 11. A support, a first thermoreversible recording layer provided above a first main surface of the support, and a second thermoreversible recording layer of the support.
In a thermoreversible recording medium comprising a second thermoreversible recording layer provided above a main surface, the first thermoreversible recording layer and the second thermoreversible recording layer comprise an electron accepting compound and an electron accepting compound. A mixture comprising a donor color-forming compound and a binder resin, wherein the electron-accepting compound is 4-hydroxydocosananilide and the electron-donating color-forming compound is 3-dibutylamino-6-methyl-7- A layer to be anilinofluoran, the electron-accepting compound to be 4-hydroxydocosananilide, and the electron-donating color-forming compound to be 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl 2-methylindol-3-yl) -4-azaphthalide, the electron-accepting compound is 4-hydroxydocosananilide, and the electron-donating color-forming compound is 3,3-bis (1- n-butyl-2-methylindole-3-yl) Thermoreversible recording medium, characterized in that the group of layers consisting of a layer of a fluoride is composed of at least one layer selected. 12. The thermoreversible recording medium according to claim 11, wherein a mixing ratio of the electron accepting compound and the electron donating color forming compound is a value within a range of 1 to 5. A thermoreversible recording medium, wherein the ratio is the weight of the electron-accepting compound / the weight of the electron-donating color-forming compound. 13. The thermoreversible recording medium according to claim 11, wherein the binder resin is polyvinyl alcohol, and the polyvinyl alcohol has a saponification degree of 80 mol% to 90 mol.
%, And the degree of polymerization is from 1000 to 40%.
A thermoreversible recording medium having a value within the range up to 00. 14. The thermoreversible recording medium according to claim 11, wherein each of the first thermoreversible recording layer and the second thermoreversible recording layer is a single layer. Thermoreversible recording medium. 15. The thermoreversible recording medium according to claim 11, wherein the first thermoreversible recording layer and the second thermoreversible recording layer are each formed by laminating two or three layers. A thermoreversible recording medium, wherein each layer constituting each of the laminates is a layer containing the electron-donating color-forming compound different from each other.