JP3264061B2 - Reversible thermosensitive recording medium - Google Patents

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 medium, and in particular, it is possible to record two kinds of different information in the same recording area by heating with a thermal head or a laser beam and to obtain a high contrast. The present invention relates to a reversible thermosensitive recording medium with improved visibility.

[0002]

2. Description of the Related Art In recent years, there have been remarkable developments in cards, such as magnetic recording media, on which machine-readable information is recorded, and these cards have been used in many fields.

[0003] In this type of card, a magnetic recording layer is provided on a card base, and information is recorded on the magnetic recording layer. Although magnetically recorded information is invisible visually, these cards require higher security, for example, outside the magnetic recording area, as an identification function for determining the authenticity of the card. A magnetic or non-magnetic recording medium is disposed, or a magnetic recording layer of a magnetic recording section is formed with a concealment layer so that magnetic recording contents are not easily read from the outside. .

In recent years, in addition to recording fixed information, identification information, and variable information on a magnetic recording layer, in order to provide the convenience of the card owner, information that can be viewed during use has been recorded on the surface of the card. Will be performed,
In particular, with prepaid cards, the same value information as in magnetic recording can be visually recognized without being read. Then, a reversible recording material that can form visible information and can erase the information when it becomes unnecessary has attracted attention.

As a typical example, the glass transition temperature (Tg) is from 50 to 60 degrees Celsius to less than 80 degrees Celsius.
A reversible thermosensitive recording material in which an organic low molecular weight substance such as a higher fatty acid is dispersed in a resin base material such as a vinyl chloride-vinyl acetate copolymer having a low glass transition temperature is known (for example, “Special Features”). No. 54-119377, "Japanese Patent Laid-Open No. 55-119377.
154198, "JP-A-4-221678"
etc).

It is known that these information recording media have already been applied, and examples thereof include a point card having a rewrite function.

As described above, reversible thermosensitive recording media have been conventionally used for products such as cards. On the other hand, with the diversification of needs, in recent years, the functions required for these media have been increasing. That is the current situation.

[0008] Among them, some reversible thermosensitive recording media require a recording material capable of recording in various types. For example, there is a demand for a recording method in which the color can be gradually and automatically erased at room temperature after printing, and a recording method in which the image can be retained without being erased after printing.

[0009] However, at present, there is no reversible thermosensitive recording medium that satisfies such requirements at the same time.

Some examples of application to a recording material using a temperature indicating material have also been proposed, for example, electronic metal complex salts, liquid crystal,
Metamocolor method and the like.

Among them, reversible thermosensitive materials utilizing a color-forming reaction between an electron-donating color-forming compound and an electron-accepting compound are widely known, such as facsimile machines, automatic ticket vending machines, printers for scientific measuring instruments, and thermostats. It has been widely applied to meters and toys.

A considerable number of such materials have been proposed, for example, temperature indicating materials disclosed in Japanese Patent Publication No. Sho 51-44706 and Japanese Patent Publication No. Sho 51-44707, and Japanese Patent Publication No. Sho 51-4.
No. 4908, thermochromic material, and JP-A-62-1408.
81 and JP-A-62-138556, and a reversible thermochromic composition and a reversible thermosensitive recording material of JP-A-4-344287.

However, these thermosensitive recording materials are:
Its use is considerably limited, and there is a problem that the recording medium must be kept within a specific temperature range in order to store the recording information.

[0014]

As described above, in the conventional reversible thermosensitive recording medium, since there is no recording material capable of recording in various types, two different types of information are recorded in the same recording area. There was a problem that it was not possible.

The present invention has been made in order to solve the above-mentioned problems, and two different types of information can be recorded in the same recording area by heating with a thermal head or a laser beam. It is another object of the present invention to provide a reversible thermosensitive recording medium capable of improving visibility as high contrast.

[0016]

In order to achieve the above object, first, a reversible thermosensitive recording medium according to the first aspect of the present invention comprises a resin base material and a resin base material provided on at least one of the supports. A first heat-sensitive recording layer comprising a low-molecular substance dispersed in a material and having a reversible change in transparency and white turbidity depending on the temperature, and at least a color former and a developer formed on the first heat-sensitive recording layer; A second thermosensitive recording layer made of a reversible thermosensitive material containing a color-reducing agent is provided.

A reversible thermosensitive recording medium according to a second aspect of the present invention comprises a resin base material and a low-molecular substance dispersed in the resin base material on at least one of the supports.
A first heat-sensitive recording layer whose transparency and white turbidity change reversibly depending on temperature is provided, and a second heat-sensitive material made of a reversible thermosensitive material containing at least a color former and a color-reducing agent is provided on the first heat-sensitive recording layer.
And a protective layer having heat resistance is provided on the second heat-sensitive recording layer.

Further, a reversible thermosensitive recording medium according to the invention according to claim 3 is the reversible thermosensitive recording medium according to claim 1 or 2, wherein the reversible thermosensitive recording medium is provided between the support and the first thermosensitive recording layer. Is provided with a coloring layer.

Here, in particular, the color former and the color-reducing agent of the second heat-sensitive recording layer are made into fine particles.

Further, the second heat-sensitive recording layer is composed of microcapsules containing at least a color former and a color-reducing agent.

[0021]

Therefore, in the reversible thermosensitive recording medium of the present invention, the support comprises a resin base material and a low-molecular substance dispersed in the resin base material, and the transparency and white turbidity depend on the temperature. By providing a first heat-sensitive recording layer that changes reversibly, and providing a second heat-sensitive recording layer made of a reversible thermosensitive material containing at least a color former and a color-reducing agent on the first heat-sensitive recording layer To a temperature higher than the specific temperature T ₀ near room temperature,
Three state transfer temperatures T ₁ , T ₂ , T ₃ (T ₀ <T ₁ <T
₂ <T ₃ ).

[0022] Thus, when heating the reversible thermosensitive recording medium in the above T ₁ of the temperature, the second heat-sensitive recording layer was color, cooling to T ₀ temperature below disappear printed after a certain time, the original (Hereinafter, this is referred to as temporary recording B).

Further, by heating the reversible thermosensitive recording medium to T ₃ or more temperature, and upon cooling after holding the T ₀ temperature below the first heat-sensitive recording layer was opaque and moreover stably retain its state (Hereinafter referred to as temporary recording A).

Furthermore, when the first heat-sensitive recording layer in the opaque state is heated to a temperature less than T ₃ at T ₂ or more temperature and cooled after holding the T ₀ temperature below returns to the transparent state again The transparent state of the first heat-sensitive recording layer can be stably maintained.

As described above, in the reversible thermosensitive recording medium of the present invention comprising the first thermosensitive recording layer and the second thermosensitive recording layer, the temporary recording A, the temporary recording Information can be recorded by two types of recording methods, recording B.

On the other hand, in the reversible thermosensitive recording medium according to the second aspect of the present invention, by providing a heat-resistant protective layer on the second thermosensitive recording layer, the heat generation of the thermal head and the temperature during use can be improved. It is possible to reliably prevent a change in gloss due to deformation of the heat-sensitive recording layer due to abrasion or the like, and the recorded information from being unable to be identified due to the change in gloss.

In the reversible thermosensitive recording medium according to the third aspect of the present invention, by providing a colored layer between the support and the first thermosensitive recording layer, the color tone of the thermosensitive recording layer can be adjusted. As a result, the contrast can be further increased and the visibility can be improved.

Further, by making the color former and the color-reducing agent of the second heat-sensitive recording layer finer, reactivity such as discoloration can be improved.

Further, by forming the second heat-sensitive recording layer from microcapsules containing at least a color former and a color-reducing agent, the material can be made transparent, and the first layer, which is the lower layer, can be obtained. The heat-sensitive recording layer becomes clearly visible.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is directed to a first type wherein a resin base material and a low-molecular substance dispersed in the resin base material are provided on a support, and transparency and white turbidity change reversibly depending on heat. By providing a heat-sensitive recording layer, on the first heat-sensitive recording layer, by providing a second heat-sensitive recording layer made of a reversible temperature indicating material containing at least a microcapsule containing at least a color former and a developer / desensitizer, to a temperature higher than the specific temperature T ₀ near room, three states transition temperature _{T 1, T 2, T 3} (T 0 <T
By providing ₁ <T ₂ <T ₃ ), information can be recorded in the same recording area by two types of methods, temporary recording A and temporary recording B, due to a change in thermal energy.

An embodiment of the present invention based on the above-described concept will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing a configuration example of a reversible thermosensitive recording medium according to the present invention.

That is, as shown in FIG. 1, the reversible thermosensitive recording medium of the present embodiment is composed of a resin base material and a low-molecular substance dispersed in the resin base material on a support sheet 1.
A first thermosensitive recording layer 2 whose transparency and white turbidity change reversibly depending on temperature is provided, and on the first thermosensitive recording layer 2,
The second thermosensitive recording layer 3 is made of a reversible thermosensitive material containing at least a color former and a color-reducing agent which are made into fine particles, or a microcapsule containing the reversible thermosensitive material.
, And a heat-resistant protective layer 4 is provided on the second heat-sensitive recording layer 3.

Here, as the base material of the support sheet 1,
For example, a synthetic resin sheet such as a polyvinyl salt for a card used for an ID card or a credit card, a polyester sheet for a card used for a prepaid card, or paper can be used.

The first heat-sensitive recording layer 2 is composed of a resin base material and a low-molecular substance dispersed in the resin base material, and its light absorption characteristics (light scattering properties) depend on temperature. It is configured using the property of reversibly changing.

That is, the first heat-sensitive recording layer 2
_When heated and maintained at a temperature of ₃ or more and then cooled to a temperature of T ₀ or less, it becomes cloudy, its light scattering property increases, and the light-shielding state becomes maximum, while the first thermosensitive recording layer 2 in this cloudy state is formed. was heated to a temperature below T ₃ at T ₂ or more temperatures, and upon cooling to T ₀ temperature below after holding, the light scattering is made transparent state decreases. Moreover, T ₀
Under the following temperature conditions, the maximum light-shielding state and the transparent state of the first thermosensitive recording layer 2 can be stably maintained, and these states can be reversibly changed. By doing so, it can be differentiated from the other state and can be used as a rewritable semi-permanent recording medium.

The low-molecular substance dispersed in the first thermosensitive recording layer 2 preferably has a melting point of about 30 to 200 degrees Celsius.

For example, lauric acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nonadecanoic acid, arachiic acid, oleic acid, eiconic acid, behenic acid, lignoceric acid, pentitaconic acid, serotinic acid, heptacosanoic acid , Montanic acid, nonacosanoic acid, melicic acid, 2-hexadecanoic acid, trans-3-
Hexadecanoic acid, 2-heptadecenoic acid, trans-2-
Octadecenoic acid, cis-2-octadecanoic acid, trans-4-octadecenoic acid, cis-6-octadecenoic acid, elaidic acid, basenic acid, trans-chondoic acid, nilucic acid, brassic acid, seracoleic acid, trans-8
Higher fatty acids such as-,-trans-10-octadecadienoic acid, linoelaidic acid, o-eleostearic acid, β-eleostearic acid, busoeleostearic acid, and 12,2-o-heneicosadienes Can be used.

Further, higher fatty acids such as methyl stearate, octadecyl stearate, octadecyl laurate, tetradecyl palmitate and docosyl behenate may be used.

Further, malonic acid, malonic acid-p-nitrobenzyl ester, malonic acid-S-
p-bromobenzyl thyuronium salt, benzyl ammonium malonate, malonic diamide, malonic anilide; succinic acid, p-nitrobenzyl succinate,
Succinic acid phenacyl ester, succinic acid Sp-chlorobenzyl thyuronium salt, succinic acid benzylammonium salt, succinic monoamide, succinic anilide, succinic dihydrazide; glutaric acid, glutaric acid phenacyl ester, glutaric acid-p -Bromophenacyl ester,
Glutaric acid-S-p-bromobenzylthiuronium salt,
Glutaric acid anilide; adipic acid, adipic acid-p-nitrobenzyl ester, adipic acid phenacyl ester, adipic acid monoamide, adipic acid anilide; pimelic acid, pimelic acid-p-bromophenacyl ester,
Pimelic anilide, pimelic dianilide, pimelic dibenzal hydrazide; suberic acid, suberic acid-p
-Nitrobenzyl ester, suberic acid phenacyl ester, suberic acid monoamide, suberic acid anilide; azaline acid, azelaic acid, azelaic acid-p-bromophenacyl ester, azelaic acid-p-phenacyl ester, azelaic acid monoamide, sebacic acid And dicarboxylic acids such as sebacic acid phenacyl ester, sebacic acid-p-phenylphenacyl ester, and sebacic acid benzylammonium salt, or derivatives thereof.

As the resin base material of the first thermosensitive recording layer 2, a transparent synthetic resin can be used.

For example, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol terpolymer, vinyl chloride-vinyl acetate-maleic acid terpolymer, vinyl chloride-acryl Vinyl chloride resins such as acid ester copolymers; polyvinylidene chloride;
Vinylidene chloride copolymers such as vinylidene chloride-vinyl chloride copolymer and vinyl chloride-acrylonitrile copolymer;
Polyacrylate, polymethacrylate,
Acrylic resins such as acrylate-methacrylate copolymers; polyesters; polyamides; silicone resins and the like can be used.

On the other hand, the second heat-sensitive recording layer 3 can be colored by heating to a temperature of T ₁ or higher, and the color-forming composition in the color-developing state is allowed to stand at room temperature of T ₀ or lower. Can be erased. The compositions this decoloring, which by heating to above T ₁ of the temperature can be again colored.

The second thermosensitive recording layer 3 is a reversible temperature indicating material capable of repeatedly performing such color development and decoloration. The second thermosensitive recording layer 3 is transparent when no color is developed. The transparency is desirably 20% or less in haze ratio.

Examples of materials used for the second thermosensitive recording layer 3 include the following examples.

As the color former, for example, leuco dyes such as xanthene, spiropyran, lactone, fluoran and sultone having a partial skeleton such as lactone, lactam, sultone and spiropyra are used, and fluoran leuco dyes are particularly preferable. They can be used alone or as a mixture.

As the color-developing agent, known ones can be appropriately used as long as the color-forming agent develops a color upon application of heat. For example, a phenol compound, a triphenylmethane compound, a sulfone compound and the like can be mentioned, and these can be used alone or as a mixture.

Further, the material can be made transparent by microencapsulating the color former and the color-reducing agent. In this case, the size of the microcapsules is preferably 3 μm or less from the viewpoint of sensitivity and transparency during thermal recording.

On the other hand, the heat-resistant protective layer 4 is not deformed by the energy of about 0.3 mJ / dot of the thermal head,
No change in gloss occurs.

The material of the heat-resistant protective layer 4 is, for example, nitrocellulose, hydroxycellulose,
Carboxymethylloose, polyvinyl alcohol, styrene-maleic acid copolymer, polyester resin, ABS
Resin or the like can be used.

Further, a thermosetting resin, an ultraviolet curing resin,
A curable resin such as an electron beam curable resin can also be used.

The thickness of the protective layer 4 is 1 to 5 μm
Is appropriate.

Further, the protective layer 4 may include a sliding material such as wax in order to improve the sliding property between the thermal head and the smooth running of the thermal head.

Next, a method for manufacturing the reversible thermosensitive recording medium of this embodiment will be described.

First, the low-molecular substance and the resin base material are dissolved or dispersed in an appropriate solvent to form a solution or a dispersion, and gravure coating, reverse roll coating, knife coating, blade coating, or the like is formed on the support sheet 1. The first heat-sensitive recording layer 2 is formed by applying by various coating methods such as gravure printing and screen printing, followed by drying.

Here, even when the low-molecular substance is dissolved in the solvent, the low-molecular substance is contained in the resin base with the drying of the solvent based on the difference in solubility between the resin base material and the low-molecular substance. To form fine crystals.

The first thermosensitive recording layer 2 is made of a resin material 10
It is desirable that the mixture be composed of a mixture of 10 to 200 parts by weight of low molecular weight with respect to 0 parts by weight. Further, the film thickness is 5 to 10
It is desirable to provide a thickness of μm.

Next, a coating solution comprising the color former and the color-reducing agent is applied together with an appropriate binder to the first heat-sensitive recording layer 2.
The second heat-sensitive recording layer 3 is formed by applying a known method such as a bar coating method, a gravure coating method, or a roll coating method, and then drying.

Here, as the binder, for example, a synthetic resin emulsion such as polyvinyl alcohol, carboxymethylcellulose, methylcellulose and polyvinylpyrrolidone can be used alone or in combination.

Finally, the material is dissolved or dispersed in a solvent, applied and dried to form the protective layer 4.

Next, a method of using the reversible thermosensitive recording medium of the present embodiment configured as described above will be described.

In the reversible thermosensitive recording medium of this embodiment, three state transition temperatures T ₁ , T ₂ , and T ₃ (T ₀ <T ₁ <T ₂₎ are set to temperatures higher than the specific temperature T ₀ near room temperature. <T
₃ ) Have.

Therefore, when the reversible thermosensitive recording medium is heated to a temperature higher than T ₁ , the second thermosensitive recording layer 3 develops color and T _0.
When cooled to the following temperature, the printing disappears after a certain period of time and returns to the original transparent state (temporary recording B).

[0064] Further, by heating the reversible thermosensitive recording medium to T ₃ or more temperature, and cooling to T ₀ temperature below after holding, the first heat-sensitive recording layer 2 is clouded, and stably in that state Can be retained (temporary record A).

Further, when the first thermosensitive recording layer 2 in the cloudy state is heated to a temperature of T ₂ or higher and lower than T ₃ , and is maintained and cooled to a temperature of T ₀ or lower, the first thermosensitive recording layer 2 returns to a transparent state again. Returning, the transparent state of the first thermosensitive recording layer 2 can be stably maintained.

That is, as described above, the reversible thermosensitive recording medium according to the present embodiment is operated while the thermal head is running.
Information is recorded by causing the heat generating element to selectively generate heat and forming a recording image on the first thermosensitive recording layer 2 or the second thermosensitive recording layer 3 by the heat energy. After forming the recorded image in this manner, the entire surface is uniformly heated by a heat roll or the like, or the portion of the recorded image is heated to a relatively high temperature (T ₂ ) using a thermal head, and is relatively cooled to a relatively low temperature (T ₀ ). As a result, the light transmittance of the recording layer increases again, and the recorded image is erased.

After the recorded image is erased, another recorded image (temporary recording A or temporary recording B) is heated again at a relatively high temperature (T ₃ ) or (or T ₁ ) and cooled. Can be formed.

Meanwhile, the second heat-sensitive recording layer 3 of the reversible thermosensitive recording medium of the present embodiment, colored on heating above T ₁ of the temperature, by which the colored state is naturally left at room temperature, decolorizing I do.

That is, the coloring composition of the coloring composition gradually decreases in coloring density with the passage of time. It is desirable that the second thermosensitive recording layer 3 can be sufficiently read by the naked eye within 5 to 10 minutes after printing.

As described above, in the reversible thermosensitive recording medium of the present embodiment comprising the first thermosensitive recording layer 2 and the second thermosensitive recording layer 3, temporary recording is performed in the same recording area by a change in thermal energy. Information can be recorded by two types of recording methods, A and temporary recording B.

Next, a more specific example of the reversible thermosensitive recording medium of this embodiment will be described.

First, as the support sheet 1, the thickness 188
A white polyester sheet for a pre-bait card having a thickness of 1 μm was used.
And a second heat-sensitive recording layer 3 was provided on the first heat-sensitive recording layer 2, and a protective layer 4 was provided on the second heat-sensitive recording layer 3.

Here, examples of the composition of the first thermosensitive recording layer 2 include the following.

3 parts by weight of vinyl chloride-vinyl acetate copolymer (S-LEC C manufactured by Sekisui Chemical Co., Ltd.) 1 part by weight of behenic acid (manufactured by Kanto Chemical Co., Ltd.) 15 parts by weight of THF (Teklahydrofuran) 15 parts by weight of the support sheet 1 The first heat-sensitive recording layer 2 was applied and dried by heating to obtain a reversible recording layer having a thickness of about 5 to 8 μm.

Examples of the composition of the ink used in the second heat-sensitive recording layer 3 include the following examples.

First, reversible thermosensitive fine particles are prepared.

Crystal violet lactone (leuco) 25 parts by weight Salt of bisphenolacetic acid and stearylamine (color-reducing agent) 50 parts by weight Methacrylic resin (binder) 15 parts by weight Stearamide (sensitizer) 15 parts by weight acetic acid Ethyl (spray-drying solvent) 5 parts by weight The above composition was mixed and dispersed well, and then spray-dried with an explosion-proof spray dryer GS-31 (Yamato Scientific) to obtain reversible thermosensitive particles of about 3 μm.

Subsequently, using the reversible thermosensitive fine particles,
An ink for the second thermosensitive recording layer 3 is prepared.

Reversible thermosensitive fine particles 20 parts by weight Potassium carbonate 10 parts by weight Stearic acid 3 parts by weight Polyester resin 5 parts by weight Tolylene diisocyanate 0.25 parts by weight Toluene 50 parts by weight After drying using a wire bar, the second heat-sensitive recording layer 3 was coated on the heat-sensitive recording layer 2 so as to have a coating thickness of about 10 μm.

Finally, FDTC OP varnish N (manufactured by Toyo Ink Manufacturing Co., Ltd.) (epoxy / polyester resin) is applied onto the second heat-sensitive recording layer 3 so as to have a dry thickness of 3 μm, and irradiated with ultraviolet rays. And cured to form a protective layer 4.

As the temporary recording A in the reversible thermosensitive recording medium produced as described above, the transparent state and the cloudy state are reversibly changed by heat. In the case of being transparent, the light incident from one side is transmitted to the other side without being scattered, so that it appears transparent. Since the recording image of the temporary recording B of the second thermosensitive recording layer 3 is on the recording image of the temporary recording A,
Since the recorded image of temporary recording B disappears in a short time, temporary recording A
There is almost no effect on reading the recorded image. The temporary recording B completely returns to the original transparent state after 8 hours at room temperature.

FIG. 2 is a plan view showing an example of the configuration of an information recording card to which the reversible thermosensitive recording medium of this embodiment is applied.

In FIG. 2, if the information recording card is, for example, a credit card of a department store, after shopping, the points are recorded on the first thermosensitive recording layer of the card display section 21 by the recording method of temporary recording A. (22 in FIG. 2),
Also, when using a cash dispenser, after dropping money, confirming information such as balance, etc., the information is recorded in the form of temporary recording B (23 in FIG. 2) due to personal or private reasons, and the information is recorded. After confirmation, it automatically returns to its original state at room temperature.

As described above, the reversible thermosensitive recording medium of this embodiment is composed of the resin base material and the low-molecular substance dispersed in the resin base material on the support sheet 1 and depends on the temperature. A first thermosensitive recording layer 2 in which transparency and opacity are reversibly changed, and a first thermosensitive recording layer 2 is formed on the first thermosensitive recording layer 2 from a reversible temperature indicating material containing at least a finely divided color former and a color-reducing agent. Or a second thermosensitive recording layer 3 comprising microcapsules containing the above-mentioned reversible thermosensitive material.
The heat-sensitive recording layer 3 is provided with a protective layer 4 having heat resistance.

Therefore, it is composed of a resin base material and an organic low-molecular substance dispersed in the resin base material, and T ₂ (T ₀ <T ₁ <
The light transmittance is increased by being heated to T ₂ <T ₃₎ or T ₃ lower than the temperature, the light transmittance is lowered by being heated to relatively high temperatures T _3, the difference in the light transmittance The first thermal recording layer 2 is provided for forming a recording image by using the first heat-sensitive recording layer 2 (temporary recording A method) which can be held unless the recorded image is erased.
_When heated to a temperature of ₁ or more and less than T ₃ , the first thermosensitive recording layer 2
Does not change, the second heat-sensitive recording layer 3 develops a color, and the color development of the second heat-sensitive recording layer 3 can be gradually erased at room temperature (temporary recording B method) to obtain a recording medium.

Thus, it is possible to record information in the same recording area by using two types of temporary recording methods, temporary recording A and temporary recording B, by using the heating energy.

Further, since two types of temporary recording methods can be selected according to the application, it can be used particularly as a recording member for various cards.

As described above, by heating with a thermal head, a laser beam or the like, two different types of information can be recorded in the same recording area, and the visibility can be improved with high contrast.

Further, as in the case of the conventional thermographic recording material, there are problems that the use is considerably limited, and that the recording medium is kept within a specific temperature range for preserving the recorded information. Becomes possible.

Further, since the protective layer 4 having heat resistance is provided on the second heat-sensitive recording layer 3, the gloss changes due to the heat generation of the thermal head and the deformation of the recording layer due to abrasion during use. It is possible to prevent the recorded information from becoming indistinguishable due to the change in gloss.

Further, by making the color former and the developer / desensitizer of the second thermosensitive recording layer 3 into fine particles, the reactivity such as discoloration can be improved, and the color former of the second thermosensitive recording layer 3 can be improved. By making the fine particles of the dye and the color-developing agent finer, the material is made transparent, so that the lower first heat-sensitive recording layer 2 can be seen well.

The present invention is not limited to the above embodiment, but can be implemented in the following manner.

(A) In the above embodiment, the second heat-sensitive recording layer 3 is made of a reversible thermosensitive material containing at least a finely divided color former and a developer / desensitizer, or contains the reversible thermosensitive material. Although the case of microcapsules has been described, the present invention is not limited to this.

(B) In the above embodiment, the case where the reversible thermosensitive recording medium of the present invention is applied to an information recording card has been described. However, the present invention is not limited to this, and the present invention can be similarly applied to other media. Things.

(C) In the above embodiment, the protective layer 4 is not an indispensable element of the present invention, but may be provided as needed.

(D) In the above embodiment, the first heat-sensitive recording layer 2, the second heat-sensitive recording layer 3,
The case where the protective layer 4 is provided has been described. However, the present invention is not limited to this.
A second heat-sensitive recording layer 3 and a protective layer 4 may be provided.

(E) In the above embodiment, by providing a colored layer between the support sheet 1 and the first heat-sensitive recording layer 2, the color tone of the heat-sensitive recording layer can be adjusted, so that the contrast is further improved. It is possible to improve the visibility by increasing the height.

The present invention can be variously modified and implemented without departing from the scope of the invention.

[0099]

As described above, according to the present invention, at least one of the supports comprises a resin base material and a low-molecular substance dispersed in the resin base material, and is transparent depending on the temperature. And a first thermosensitive recording layer in which cloudiness changes reversibly,
On the first heat-sensitive recording layer, a second heat-sensitive recording layer made of a reversible thermosensitive material containing at least a color former and a color-reducing agent is provided, and if necessary, heat resistance is provided on the second heat-sensitive recording layer. A protective layer is provided, and if necessary, a colored layer is provided between the support and the first heat-sensitive recording layer. Therefore, by heating with a thermal head or a laser beam, the same recording area can be obtained. It is possible to provide a reversible thermosensitive recording medium in which two different types of information can be recorded, and high contrast and improved visibility can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a reversible thermosensitive recording medium according to the present invention.

FIG. 2 is a plan view showing a configuration example of an information recording card to which the reversible thermosensitive recording medium in the embodiment is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Support sheet, 2 ... 1st thermosensitive recording layer, 3 ... 2nd thermosensitive recording layer, 4 ... Protective layer.

Continuation of the front page (56) References JP-A-63-84978 (JP, A) JP-A-7-9764 (JP, A) JP-A-7-108758 (JP, A) JP-A-4-345886 (JP) , A) (58) Field surveyed (Int.Cl. ⁷ , DB name) B41M 5/38-5/40 B41M 5/28-5/34 C09K 9/02

Claims (5)

(57) [Claims] 1. A resin base material and a low-molecular substance dispersed in the resin base material on at least one of the supports,
A first heat-sensitive recording layer in which transparency and white turbidity change reversibly depending on the temperature is provided; and 2. A reversible thermosensitive recording medium, comprising: a thermosensitive recording layer according to (2). 2. A method according to claim 1, wherein at least one of the supports comprises a resin matrix and a low-molecular substance dispersed in the resin matrix.
A first heat-sensitive recording layer in which transparency and white turbidity change reversibly depending on the temperature is provided; and 2. A reversible thermosensitive recording medium, comprising: a second thermosensitive recording layer; and a heat-resistant protective layer provided on the second thermosensitive recording layer. 3. The reversible thermosensitive recording medium according to claim 1, wherein a coloring layer is provided between the support and the first thermosensitive recording layer. Thermosensitive recording medium. 4. The reversible heat-sensitive material according to claim 1, wherein the color former and the color-reducing agent of the second heat-sensitive recording layer are finely divided. recoding media. 5. The method according to claim 1, wherein the second heat-sensitive recording layer is composed of microcapsules containing at least a color former and a color-reducing agent.
The reversible thermosensitive recording medium according to any one of the above items.