JPH06106849A - Heat-sensitive recording medium and its recording method - Google Patents

Abstract

PURPOSE:To provide a heat-sensitive recording medium for the protection of information and prevention of illegal usage by means of a display by forming a recording layer constituted by means of a reversible heat-sensitive recording material and an irreversible heat-sensitive recording material prepared by a resin wall on a substrate. CONSTITUTION:A reflective layer 2 is formed on a substrate 1 such as a plastic sheet by aluminum deposition. A recording layer 3 comprising microcapsules provided with a reversible heat-sensitive recording material 6 as a core and a capsule material 5 as a resin wall dispersed in an irreversible heat-sensitive recording material 7 is laminated on the reflective layer 2, over which a wear- resistant surface protective layer 4 is laminated to provide a heat-sensitive recording medium. As organic crystal particles of the reversible heat-sensitive recording material, a straight-chain aliphatic compound with one or more hydrogen bonding radicals is suitable. As a representative example of a reaction coloring matter, the irreversible heat-sensitive recording material, 3,3'-bis(p- dimethylaminophenyl)-phthalide or the like is available.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording medium which can be reversibly recorded and erased by heating, and can also be used for irreversible recording if necessary. INDUSTRIAL APPLICABILITY The present invention is most effective when used for a rewritable memory card with a display function, which is used as a prepaid card such as a commuter pass, a ticket, and a coupon ticket, and an IC card, a recording paper for facsimile, and a heat-sensitive recycled paper. .

The reversible thermosensitive recording material is often used as a recording medium such as a card or a sheet. For example, when used for a card, the reversible thermosensitive recording layer displays personal information and usage information with a thermal head such as a thermal head, and the information display can be rewritten and changed for each use for repeated use. You can In order to protect information, important information that does not need to be changed or updated information is stored not only by display but also by magnetic recording or IC. Also, when used as a sheet, it can be used repeatedly by displaying characters etc. with a thermal head, a thermal pen, etc. like normal thermal paper and erasing it when it is not needed and making a new display. Available as recycled paper.

[0003]

As a reversible thermosensitive recording material in this field,
A heat-sensitive recording material has been proposed which utilizes the melting and solidification behavior of organic crystal particles in a matrix polymer and changes in the transparency of the particles depending on the heating conditions. That is, in this heat-sensitive recording material, crystalline fine particles are melted by heat and solidified again, and the transparency of the solidified form (polycrystalline state, single crystalline state, amorphous state, etc.) is changed depending on the condition, and recording is performed.

As this material, for example, JP-A-54-1 is used.
As disclosed in Japanese Laid-Open Patent Publication No. 19377, it is composed of a matrix polymer and the following fusible organic molecules in combination, so that various recording materials can be composed. The organic molecules disclosed herein include aliphatic and aromatic alcohols, carboxylic acids, amines, amides and their halides, sulfides, and the like. On the other hand, as the matrix polymer, general polymers such as polyester, polyamide, polyacrylic acid, styrene, silicone, polyvinyl chloride, polyvinylidene chloride and polyacrylonitrile are disclosed.

A recording material obtained by improving this and further adding carbon black and an antioxidant is disclosed in JP-A-57-8.
It is disclosed in Japanese Patent No. 2087 and Japanese Patent Laid-Open No. 57-82088.

However, these compounds that have been studied in many cases have a relatively low transparency temperature of several tens of degrees Celsius, so that the storage stability of recording is inferior and the width thereof is narrow as several degrees Celsius. There was a problem that there was no degree. For example, behenic acid having a carbon number of 22 (melting point: 80 ° C.), which is a typical linear saturated fatty acid capable of obtaining high contrast, is used, and in the reversible thermosensitive recording material in combination with a vinyl chloride / vinyl acetate copolymer, it is transparent. Since the temperature range is about 68 ° C. to 74 ° C. and the width is narrow at about 6 ° C., there is no recording margin and it is difficult to perform stable recording.

As a method for improving such a low transparency temperature and a narrow temperature range, attention is paid to the action of interaction between the hydrogen bonding property of the organic molecules constituting the organic crystal particles and the matrix polymer having a hydrogen bonding group. Then, a reversible thermosensitive recording material having a high and wide transparency temperature region and capable of stable recording is disclosed in, for example, Japanese Patent Application No. 3-64857.

Further, there is also a demand for improving the reliability in use of the recording medium in this field, including the prevention of fraud. As a method for preventing the unauthorized use of the rewritable and displayable card, a method of thermally destroying the display mechanism of the reversible thermosensitive recording material by a heating destruction mechanism that applies excessive heat is disclosed in, for example, JP-A-3-255594. ing.

[0009]

When a reversible thermosensitive recording medium is used, it is displayed on a reversible thermosensitive recording layer made of a material having storage stability of recording even when information is not rewritten and is not rewritten. You can also do it. However, in order to protect the information more accurately, it is necessary to use a recording material that does not easily erase the information displayed in the living environment, and it is effective to have a recording function only once, for example. Further, the displayed information is protected so that the information cannot be rewritten, so that the effect of preventing fraud can be provided. When a magnetic card, an IC card, or the like is provided with a display function of a reversible thermosensitive recording material, it can be recorded on the magnetic recording layer or the IC, in addition to the display on the reversible thermosensitive recording layer. There is no loss of records, and fraud can be prevented.

However, in the case of a recording medium having a display function, it is necessary to visually confirm it in order to prevent troubles and reliability. The method disclosed in Japanese Patent Laid-Open No. 3-255594 for preventing unauthorized use by visual inspection is for a used card and loses the reversible display function, so that it cannot be used thereafter.

Therefore, an object of the present invention is to provide a recording medium having a rewritable display function using a reversible thermosensitive recording material.
An object of the present invention is to provide a thermosensitive recording medium capable of protecting information by display and preventing fraud by providing an irreversible recording function capable of recording only once.

[0012]

The present invention comprises an organic crystal particle having a hydrogen-bonding group and a matrix polymer having a hydrogen-bonding group, wherein the organic crystal particle has a reversible transparency by heating and cooling. A reversible thermosensitive recording material that changes and an irreversible thermosensitive recording material that exhibits color development or decolorization by heating are solved by the thermosensitive recording medium having a recording layer separated by a resin wall to solve the conventional problems described above. Achieved the purpose.

[0013]

The reversible thermosensitive recording material of the recording layer of the thermosensitive recording medium of the present invention has a structure in which organic crystal particles having one or more hydrogen-bonding groups are mixed in a matrix polymer containing hydrogen-bonding groups. In addition, the contrast is high, the transparency start temperature is 60 ° C. or higher, and the transparency temperature range is 20 ° C. or higher. With this material structure, the recording characteristics are significantly improved, and the storage stability of recording such as information protection is improved.

Further, the heat-sensitive recording medium of the present invention has a constitution including the reversible heat-sensitive recording material and the irreversible heat-sensitive recording material. Since the two heat-sensitive recording materials are separated from each other by the resin wall, they do not mix with each other and can be independently recorded. Moreover, in the irreversible heat-sensitive recording material, only the irreversible heat-sensitive recording material causes a hue or lightness change called coloring or decoloring for recording. Since recording due to this hue change appears independently, it does not affect the reversible thermosensitive recording material,
Permanent recording is possible.

[0015]

EXAMPLES The recording layer of the thermosensitive recording medium of the present invention comprises a reversible thermosensitive recording material and an irreversible thermosensitive recording material, and has an irreversible function capable of recording only once while maintaining the reversible recording performance. It is characterized by this.

As the irreversible thermosensitive recording material, a compound which develops or decolorizes by heating can be applied. Examples of such a heat-responsive compound include a thermosensitive dye or a thermochromic dye whose hue changes by heating reaction with a color developing agent or a decoloring agent.

Among the heat-sensitive dyes, the leuco compound has a reaction coloring property and a reaction decoloring property as described below, and a material can be appropriately selected according to the application.

That is, when a material containing a reaction color-forming dye composed of a leuco compound as a main component and a developer as a substance which develops color upon heating, many combinations of leuco compound and developer are possible. Also, the temperature design for irreversible recording can be performed by selecting the color developer, and the display color can be selected by selecting the reaction color forming dye, which is preferable. As the reaction color-forming dye comprising a leuco compound, generally, a triphenylmethane-based or fluorane-based colorless or faint color dye having a lactone or lactam type reaction color-forming component in the molecule is used, and as a developer, ,In general,
Phenolic substances or organic acids are used. Furthermore, these materials are generally dispersed in a binding polymer, and a thermosoftening resin is used as the binding polymer.

When the irreversible thermosensitive recording material is a compound which is decolorized by heating, the above-mentioned leuco compound (reactive color-developing dye) is reacted with a developer in advance to develop a color, and a reaction-decolorable dye. A material containing a colorant as a main component is used.
As the decoloring agent, for example, an aliphatic compound or a polymer compound having an amino group is used.

In addition to these compounds, compounds such as cyanine dyes can also be used for decolorization by decomposition by heat, isomerization and the like.

In order to obtain excellent recording performance with these material configurations, it is necessary that the reversible thermosensitive recording material and the irreversible thermosensitive recording material have recording stability and a margin. The margin is preferably a color development starting temperature of 10 ° C. or higher than the transparency temperature range of the reversible thermosensitive recording material, and the recording stability such as recording storage is irreversible with a color development starting temperature of 90 ° C. or more. It is preferable to use a thermosensitive recording material.

As a constitution in which the reversible thermosensitive recording material and the irreversible thermosensitive recording material are combined, a method of simply mixing the two or laminating them can be easily considered. But,
Since the organic crystal particles used in the reversible thermosensitive recording material of the present invention have a hydrogen-bonding group, they may act as a color developer of the irreversible thermosensitive recording material, and the performance is simply obtained by mixing or laminating. Can't get Therefore, one of the constitutional requirements of the recording layer of the thermosensitive recording medium of the present invention is that the reversible thermosensitive recording material and the irreversible thermosensitive recording material are separated by a resin wall.

First, when the reversible thermosensitive recording material and the irreversible thermosensitive recording material are laminated, the constitution of the reversible thermosensitive recording material and the irreversible thermosensitive recording material depends on whether the irreversible thermosensitive recording material is a reaction color developing or a reaction erasing property. The order is different.

When an irreversible thermosensitive recording material (reactive coloring) that develops color by heating is used, a recording composed of the reversible thermosensitive recording material so that the cloudy state of the reversible thermosensitive recording material does not hide the color developed state of the irreversible thermosensitive recording material. A recording layer made of an irreversible heat-sensitive recording material is laminated on the layer via a resin wall to separate the layers.

When an irreversible heat-sensitive recording material that is decolored by heating is used, a recording layer made of a reversible heat-sensitive recording material is provided on the recording layer made of the irreversible heat-sensitive recording material through a resin wall, contrary to the above. It is necessary to stack and separate them.

When either or both of the reversible thermosensitive recording material and the irreversible thermosensitive recording material are microencapsulated and both encapsulating materials are used as resin walls to separate the two recording materials in the recording layer, the recording state of each other The thickness of the recording layer is preferably close to the size of the microcapsules so that the recording performance is not deteriorated by hiding the recording medium. With this configuration, since the recording materials do not substantially overlap with each other, the respective display records can be recognized well. The material of the resin wall is preferably a resin suitable for both recording materials, such as affinity, adhesiveness and optical performance.

As a first constitutional example of the recording layer of the thermosensitive recording medium of the present invention, for example, as shown in FIG. 2, a reversible thermosensitive recording layer 6 made of a reversible thermosensitive recording material is made of an irreversible thermosensitive recording material which develops color by heating. The irreversible thermosensitive recording layer 7 is attached to the resin wall 5
A recording layer 3 is formed by stacking the layers. With this configuration, each of the reversible thermosensitive recording layers 6 and 7 can be independently recorded, and the reversible thermosensitive recording layer 6 made of the reversible thermosensitive recording material is clouded to display a color on the white base. Can be done. However, if the irreversible heat-sensitive recording layer 7 made of the irreversible heat-sensitive recording material is not arranged on the reversible heat-sensitive recording layer 6 made of the reversible heat-sensitive recording material but placed in the reverse arrangement, the irreversible heat-sensitive recording material is clouded during the irreversible recording. The coloring of the material is hidden. Therefore, when the irreversible thermosensitive recording layer 7 has a reaction color development, it is necessary to provide the irreversible thermosensitive recording layer 7 on the reversible thermosensitive recording layer 6.

In the case of a reversible thermosensitive recording material and an irreversible thermosensitive recording material which is decolored by heating as a second structural example of the recording layer of the thermosensitive recording medium of the present invention, the recording layer 3 described in FIG.
The arrangement is reversed from the first configuration. That is, if the recording layer made of the reversible thermosensitive recording material is not arranged on the recording layer made of the irreversible thermosensitive recording material, the transparent or cloudy state of the reversible thermosensitive recording material is hidden by the initial color development state during reversible recording.

As a third structural example of the recording layer of the thermosensitive recording medium of the present invention, a reversible thermosensitive recording material 6 as shown in FIG.
(Reversible thermosensitive recording material 6A in a transparent state and cloudy (opaque)
The reversible thermosensitive recording material 6B in the state is collectively referred to as the reversible thermosensitive recording material 6), and the microcapsules having the encapsulating material 5 as a resin wall are used as the reaction coloring dye 8 (the reaction coloring dye before coloring 8A). , The reaction coloring dye 8B after the reaction is generically referred to as the reaction coloring dye 8) and the developer 9 (the developer 9A before the reaction coloring and the developer 9B after the reaction coloring are collectively referred to as the development. And a irreversible heat-sensitive recording material (reaction color-forming dye 8, developer 9, heat-softening transparent polymer 10) containing the colorant 9. Alternatively, microcapsules containing the organic crystal particles of the reversible thermosensitive recording material as the core and the matrix polymer of the reversible thermosensitive recording material as the encapsulant are mixed and dispersed in the irreversible thermosensitive recording material using the encapsulant of the matrix polymer as the resin wall. However, in any case, the thickness of the recording layer is controlled by the microcapsules of the reversible thermosensitive recording material so that the thickness is almost close to the size of the capsules.
In this configuration, the irreversible thermosensitive recording material serves as the base of the recording layer, and the irreversible thermosensitive recording material before heat-sensitive color development is transparent or faint, so that the reversible thermosensitive recording performance does not affect the recording of transparent or opaque recording. Display can be performed. The irreversibly recorded area can be reversibly recorded in a transparent or opaque state even in a colored state without hiding the reversible recording state.

Further, as a fourth constitutional example of the recording layer of the thermosensitive recording medium of the present invention, contrary to the above-mentioned third constitutional example, microcapsules having an irreversible thermosensitive recording material as a core, and encapsulating material made of resin are used. As a wall, it is mixed and dispersed in the reversible thermosensitive recording material. Also in this structure, the thickness of the recording layer is controlled by the microcapsules of the irreversible heat-sensitive recording material, and the coating is performed to a thickness close to the size of the capsule. In this configuration, the reversible thermosensitive recording material serves as the base of the recording layer, becomes transparent in the erased state, and becomes cloudy in the reversible recording state.
Then, in the irreversible recording state, recording display is performed depending on the coloring state of the capsule.

Further, as a fifth structural example of the recording layer of the thermosensitive recording medium of the present invention, as shown in FIG. 4, for example, microcapsules containing a reversible thermosensitive recording material containing organic crystal particles 11 and a matrix polymer 12, Microcapsules containing the irreversible thermosensitive recording material 7 are mixed and dispersed in a transparent base polymer 13. Even with this configuration, the thickness of the recording layer 3 can be controlled to the size of either one or both of the microcapsules, and good reversible recording and irreversible recording can be performed.

Next, FIG. 5 shows the recording temperature characteristics as an example of the recording temperature characteristics of the recording layer containing the reversible thermosensitive recording material and the additional reverse thermosensitive recording material which develops color by heating.

The solid line shows the characteristics of a reversible thermosensitive recording material which is composed of a polymer composition in which organic crystal particles are dispersed in a matrix polymer and whose transparency is reversibly changed by heating and cooling the organic crystal particles. This reversible heat-sensitive recording material, by the thermal interaction between the organic crystal particles and the matrix,
Immediately after the production, the crystal grains were light-scattered in a polycrystalline state and became cloudy. However, crystallization progressed from a certain temperature range (T ₁ ; the lower limit of the transparentization temperature range of the reversible thermosensitive recording material), and the scattering disappeared to become transparent. Become. Then, the organic crystal particles are melted (T ₂ ; the upper limit of the transparentization temperature region of the reversible thermosensitive recording material) and cooled, and then polycrystallized again to become cloudy. Since both the white turbid state and the transparent state can be repeated by the applied heat temperature, reversible recording / erasing can be realized.

The broken line shows one characteristic example of the irreversible thermosensitive recording material containing a reaction color-forming dye of a leuco compound, a developer and a binding polymer as main components.

However, as described above, this constitution is such that the color development start temperature (T ₃ ) is 10 ° C. or more higher than the clearing temperature range (T _{1 to} T ₂ ) of the reversible thermosensitive recording material used, and the color development is performed. A material property having a starting temperature T ₃ of 90 ° C. or higher is preferable.

The condition that the color development start temperature is 10 ° C. or more higher than the clearing temperature range of the reversible thermosensitive recording material requires a recording margin such as stability of display performance when recording by applying heat energy. Is.

Further, the condition of having a color formation starting temperature of 90 ° C. or higher is for recording stability such as recording storability that prevents display information from being easily erased in a daily use environment after once irreversible recording. is there.

As a recording method for the heat-sensitive recording medium, the reversible heat-sensitive recording material is made transparent by setting the transparent state of the reversible heat-sensitive recording material at the temperature (T _{1 to} T ₂ ) in the transparentization temperature region to make the reversible heat-sensitive recording material transparent. The temperature in the temperature region (T _{2 to} T ₃ ) from the upper limit temperature of the temperature region to the color development start temperature of the irreversible thermosensitive recording material is used to make the erasable recording state into the erasable recording state. Reversible recording is performed by alternately applying energy (reversible recording mode). Furthermore, by using a temperature (≧ T ₃ ) which is higher than the color development start temperature of the irreversible thermosensitive recording material,
Irreversible recording is performed by setting the color-developed state to a non-rewritable recording state (irreversible recording mode). Then, the reversible recording mode and the irreversible recording mode are switched depending on the importance of the recorded information, and the recording display is performed.

The thermal recording medium of the present invention will be described with reference to the medium configuration diagram of FIG. 1 and the recording temperature characteristic of FIG.

The recording layer 3 of the present invention is formed on the supporting substrate 1 on which the reflecting layer 2 is formed by aluminum vapor deposition. A wear-resistant surface protective layer 4 is further formed on the recording layer 3. However, when the recording portion of the thermal recording medium of the present invention is combined with, for example, a magnetic recording medium other than the recording layer of the present invention, a magnetic recording layer is formed on the support base 1, and when combined with, for example, an IC. Is the supporting substrate 1
An IC embedding part and an electrode part are formed in the. Further, the reflective layer 2 may not be necessary when the recorded display is observed through the transmission, depending on the usage of the recording medium. Note that FIG.
As shown in FIG. 5, when at least one of the reversible thermosensitive recording material and the additional inverse thermosensitive recording material of the recording layer 3 is microencapsulated, the thickness of the recording layer 3 is substantially equal to the size of the microcapsule. ing.

The recording layer 3 has a transparent thermosoftening polymer 1 as shown in FIG. 3, for example, in which the reaction color-forming dye 8A made of a leuco compound and the developer 9A are isolated from each other, as in the third structure.
A reversible thermosensitive recording material 6A containing, as main components, a matrix polymer composed of a thermoplastic transparent polymer having hydrogen bonding groups and organic crystal particles in an irreversible thermosensitive recording material dispersed in 0.
Are separated by the encapsulant 5 which is a resin wall, and are transparent in this state. This thermal recording medium
In the reversible recording mode, the reversible thermosensitive recording material 6A in the capsule is clouded and scattered by the process of applying and cooling the heat energy to reach the temperature range of T _{2 to} T _{3 in} FIG.
Is displayed, the display becomes transparent in the range of T _{1 to} T ₂ , and the display is erased. Furthermore, in the irreversible recording mode, T
_When heat energy of a temperature of ₄ or more is applied, the reaction color-forming dye 8A reacts with the developer 9A in the base irreversible thermosensitive recording material (8A, 9A and 10) to develop a color, and after the reaction color development An irreversible change occurs between the dye (often equivalent to a reaction decolorizable dye) 8B and the developer 9B after the reaction color development.

First, the reversible thermosensitive recording material used in the present invention will be described. The organic crystal particles of the reversible thermosensitive recording material used in the present invention are organic compounds having one or more hydrogen bonding groups, and linear aliphatic compounds are preferable. Also,
In order to have a clearing temperature region width of 20 ° C. or more and to obtain good recording characteristics, recording stability, and margin, two or more compounds are mixed to form a crystal grain, and the melting point of the crystal grain is Is preferably in the range of 60 to 120 ° C. For example, the linear aliphatic compound having one hydrogen-bonding group has two hydrogen-bonding properties such as a linear saturated fatty acid having a carboxyl group, a higher alcohol having a hydroxyl group, and a linear fatty acid amide having an acid amide group. Aliphatic hydroxycarboxylic acid, aliphatic dicarboxylic acid and the like are used as the materials, and they are combined to form crystal particles. Representative compounds include stearic acid, arachidic acid, behenic acid,
Stearyl alcohol, behenyl alcohol, stearic acid amide, behenic acid amide, erucic acid amide, hydroxystearic acid, hydroxypalmitic acid, hydroxystearic acid amide, eicosane diacid, hexadecane diacid, sebacic acid and the like are used. These linear aliphatic compounds are also industrially used as lubricants for resins, sensitizers for heat-sensitive recording paper, antiblocking agents for toners, etc., and have low toxicity, and are used for direct contact with consumers. It is suitable for the material.

On the other hand, generally, the matrix polymer of the reversible thermosensitive recording material includes polyester, polyacrylic acid ester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, cellulose acetate, polyvinyl butyral, polystyrene, styrene-butadiene copolymer. However, a hydrogen-bonding group-containing transparent matrix polymer is particularly suitable. The reason for this is that the interaction between the hydrogen-bonding groups present on the surface of the organic crystal particles in the composite and the hydrogen-bonding groups contained in the matrix polymer changes the behavior of transparency change, resulting in excellent recording characteristics. can get. Specific examples include adhesive (OH group-containing) polyester, partially saponified vinyl acetate-vinyl chloride copolymer, polyamide, polyurethane, thermoplastic phenolic resin, vinyl alcohol copolymer, acrylic acid copolymer, acrylamide copolymer. Polymer,
Maleic acid copolymers and the like are suitable. Since the recording material of the present invention is a thin film, considerable transparency can be obtained. Also,
Of course, it is natural to use a plasticizer in combination therewith.

The organic crystal particles constituting the reversible thermosensitive recording material are added in an amount of 5 to 60 with respect to the matrix polymer.
It can be added in the range of%. If the ratio of the organic crystal particles is higher than this, the binding force will be weakened and it will be difficult to perform a uniform coating as a recording material. On the other hand, when the ratio of the matrix polymer is high, the amount of organic crystal particles is small, so that it becomes difficult to make the opaque and the contrast of recording is deteriorated. However, the addition amount of the organic crystal particles to the matrix polymer is preferably 10 to 30%.

Next, the irreversible thermosensitive recording material of the present invention will be described. There are a wide variety of organic leuco compounds that have a lactone or lactam type electron-donating color component in the molecule, and a wide variety of hues can be selected, and reaction-coloring dyes can also be applied as reaction-decoloring dyes. Also, the selectivity of the decolorization start temperature is abundant and preferred, and typical compounds are triphenylmethane-based 3,3′-bis (p-dimethylaminophenyl) -phthalide and 3,3′-bis (p
-Dimethylaminophenyl) -6-dimethylaminophthalide [crystal violet lactone], 3,3 '
-Bis (p-dimethylaminophenyl) -6-diethylaminophthalide and other fluorane-based 3-dimethylamino-6-methoxyfluorane, 7-acetamino-
3,7-bis (diethylamino) -9-xanthenyl-o-benzoic acid lactam [rhodamine B lactam], 3,7-dimethylfluorane, 3,6-bis-β-methoxyethoxyfluorane, etc. , 6-bis (dimethylamino) -9-thioxanthenyl-o-benzoic acid lactam and the like are used.

The color developer is an organic compound having an electron-accepting phenolic hydroxyl group or an alcoholic hydroxyl group, and a typical compound is α-of a phenolic substance.
Naphthol, β-naphthol, 4-hydroxydiphenoxide, 4-tert-butylphenol, 4,4 ′
-Isopropylidene diphenol [bisphenol A], methyl-4-hydroxybenzoate, 4-hydroxyacetophenol, 4,4'-cyclohexylidene diphenol, hydroquinone and the like alcoholic substances are m-oxybenzoic acid and p-oxybenzoic acid. Acid, salicylic acid, 4-oxyphthalic acid, gallic acid and the like are used.

The decoloring agent is required to have an electron donating property, and an aliphatic amine such as stearylamine, dodecylamine or cetylamine, or a polymer such as polyaminostyrene in which polystyrene is partially aminated is used.

The binding polymer is a heat-softenable transparent polymer which binds a dye and a reaction color developing or decoloring agent, and many common polymers are used, but polyvinyl alcohol,
Polyvinylpyrrolidone, hydroxyethyl cellulose,
Methoxycellulose, carboxymethylcellulose and the like are suitable.

The recording temperature of the irreversible heat-sensitive recording material is generally determined by the combination of the reactive dye and the reactive agent dispersed in the heat-softenable transparent polymer, and in particular, the melting point or softening point of the reactive agent is considered to greatly affect the characteristics. ing.

Next, the materials used for the resin wall will be described. The resin wall is used for the purpose of preventing the organic compounds contained in the reversible thermosensitive recording material and the irreversible thermosensitive recording material from interacting with each other. As the material, the materials mentioned above as the matrix polymer of the reversible thermosensitive recording material can be used. For example, polyester, polyacrylic acid ester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, styrene-butadiene copolymer,
Ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, olefin-based copolymer, gelatin,
Suitable are ethyl cellulose, polystyrene, polyamide, various water-soluble resins, and water-based emulsion resins. When the capsule is used as a resin wall for microencapsulation, a coacervation method, an interfacial polymerization method, in s
In situ polymerization method, chemical manufacturing method such as interfacial hardening coating method with addition of curing agent, method utilizing phase separation, liquid drying method, spray drying method, fluid coating method, air suspension coating method, etc. It can be made using the manufacturing method.

The recording medium using the recording layer of the present invention, if provided with the abrasion-resistant surface protective layer 4, should constitute a recording medium which is less deteriorated with time even when contacted by a thermal head and has high durability. You can This recording medium can be written and erased in a heat mode not only by a thermal head but also by a laser. A heat roller may be used for erasing. The protective layer is required to have mechanical strength and flexibility in addition to thermal stability, and further, transparency is required as an optical property in order to read information from the recording layer well. Generally, the material of the protective layer is a cellulose resin, styrene resin or styrene copolymer resin, acrylic resin or methacrylic resin or copolymer resin thereof, polyester resin, butyral resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride. / Vinyl acetate copolymer resin, polyurethane resin, acrylate radiation curing resin, etc. can be applied.

Examples of the material of the supporting substrate 1 applied to the present invention include ordinary polymer materials such as polyester resin, polycarbonate resin, acrylic resin, metal materials such as aluminum and stainless steel, and ceramics such as glass. However, it may be appropriately selected depending on the purpose of use. The polymer material is often used in the form of a sheet, and the sheet supporting base material 1 is selected in consideration of conditions such as strength and rigidity as a material. Nylon, cellulose acetate resin, polystyrene, polyethylene,
Plastics such as polypropylene, polyester, polyimide, polycarbonate and polyvinyl chloride may be used alone or in combination, and polyester or polyvinyl chloride is practical as the support. It also requires a sufficient thickness to hold the sheet structure by mechanical strength. The film thickness is often about 0.005 to 5 mm. A reflection layer 2 for improving the contrast of the recording layer 3 is often formed and used on the sheet supporting base material 1. Further, as the sheet supporting base material 1, an information recording portion such as a magnetic recording layer or an IC may be formed by a method other than thermal recording.

Next, the present invention will be described with reference to examples. (Example 1) A recording medium having a first structure was formed by laminating an irreversible recording layer on a reversible thermosensitive recording layer via a resin wall.

(Reversible thermosensitive recording layer) 6 parts by weight of behenic acid as organic crystal particles, 4 parts by weight of stearic acid amide, and 30 parts by weight of partially saponified vinyl chloride / vinyl acetate copolymer (hydroxyl group ratio about 3%) as a matrix polymer. Parts,
A solution prepared by mixing and dissolving 200 parts by weight of tetrahydrofuran on a polyethylene terephthalate sheet having a thickness of 100 μm and having an aluminum vapor-deposited film formed as a reflective layer is applied to have a dry film thickness of about 7 μm and dried at about 130 ° C. to form a reversible thermosensitive recording layer. Obtained.

(Resin Wall Layer) On the reversible thermosensitive recording layer prepared as described above, a polyester water-based emulsion resin having a solid content of 20% was applied and dried at 90 ° C. to give a film thickness of about 1
A resin wall of μm was obtained.

(Irreversible thermosensitive recording layer) 30 parts by weight of crystal violet lactone was added as a reaction coloring solution.
A solution having an average particle size of about 1 μm dispersed in 200 parts by weight of polyvinyl alcohol of 0% by weight, and 30 parts by weight of bisphenol A as a developer were dispersed in 200 parts by weight of polyvinyl alcohol of 10% by weight with an average particle size of about 1 μm. The solution was mixed with the solution at a ratio of 1:20 to obtain a solution. This solution was applied onto the resin wall layer to obtain an irreversible thermosensitive recording layer having a dry film thickness of about 5 μm.

(Recording Medium) A recording medium was obtained by coating the recording layer with a UV-curable acrylic resin as a wear-resistant surface protective layer to a thickness of 3 μm.

This recording temperature characteristic is such that the clearing temperature region is about 68 to 90 ° C. and the width is about 22 ° C., it can be turbid at 90 ° C. or more, and the color develops from about 100 ° C. to blue and is saturated at about 150 ° C. To do. This recording medium is heated to 80 ° C using a heat-sensitive roller.
When reversible recording was performed at 95 ° C. using a thermal head, clear erasure of the display due to transparency and clear display of character information due to cloudiness were observed. Further, when irreversible recording was performed using a thermosensitive head to develop color at 140 ° C., the irreversible thermosensitive recording material was colored at the same time as clouding of the reversible thermosensitive recording material, and clear blue character information could be displayed.

The display by this irreversible recording could be well preserved in the subsequent repeated reversible thermosensitive recording.

Example 2 A recording medium having a second structure was formed by laminating a reversible recording layer on a non-reversible thermosensitive recording layer via a resin wall.

(Irreversible thermosensitive recording layer) 10 parts by weight of 30 parts by weight of a reaction-decolorable dye exhibiting a blue color obtained by heating and reacting crystal violet lactone, which is a reactive color-forming dye, and gallic acid, which is a developer, are heated. A solution having an average particle diameter of about 1 μm dispersed in 200 parts by weight of polyvinyl alcohol,
A solution prepared by dispersing 30 parts by weight of polyaminostyrene in 200 parts by weight of polyvinyl alcohol of 5% by weight was added to a solution of 5: 1.
To obtain a solution. This solution was applied to a 100 μm-thick polyethylene terephthalate sheet on which a vapor-deposited aluminum film was formed as a reflective layer in a dry film thickness of about 6 μm.
Vacuum drying was performed at about 80 ° C. to obtain an irreversible thermosensitive recording layer.

(Resin Wall Layer) On the irreversible thermosensitive recording layer prepared as described above, a polyester aqueous emulsion resin having a solid content of 20% was applied and dried at 90 ° C. to obtain a resin wall having a film thickness of about 1 μm. It was

(Reversible Thermosensitive Recording Layer) A solution of the same reversible thermosensitive recording material as that used in Example 1 was coated on the resin wall layer and the solution was coated with 10
Drying was performed at 0 ° C. to obtain a reversible thermosensitive recording layer having a dry film thickness of about 8 μm.

(Recording medium) A recording medium was obtained by coating the recording layer with a UV-curable acrylic resin as a wear-resistant surface protective layer to a thickness of 3 μm.

In this recording medium, the reversible thermosensitive recording material in the upper layer is transparent and the blue color of the irreversible thermosensitive recording material in the lower layer is blue in the erased state. The recording characteristics are about 68-
At 90 ° C, the width is about 22 ° C, and at 90 ° C or higher, it becomes cloudy,
From about 150 ° C., polyaminostyrene acts on the colored reaction-erasable dye compound to erase the color. When erasing was performed at 80 ° C. using a heat sensitive roller and reversible recording was performed at 95 ° C. using a heat sensitive head, clear erasing of the display and clear opaque character information display were observed. Further, when irreversible recording was carried out by erasing the color at 170 ° C. using a thermal head, the irreversible thermosensitive recording material was erased at the same time as the white turbidity, and it was possible to display character information in which blue was omitted.

Example 3 A reversible thermosensitive recording material was microencapsulated to form a recording medium having a third structure.

(Reversible Thermosensitive Recording Material) 6 parts by weight of behenic acid as organic crystal particles, 4 parts by weight of stearic acid amide, and 30 parts by weight of partially saponified vinyl chloride / vinyl acetate copolymer (hydroxyl ratio about 3%) as a matrix polymer. Parts, and mixed and dissolved in 300 parts by weight of tetrahydrofuran, and atomized by a spray drying method with hot air at about 130 ° C. Of these, particles having an average particle size of 18 μm were coated with ethyl cellulose as an encapsulant by the air suspension coating method to obtain microcapsules as a reversible thermosensitive recording material.

(Irreversible Thermosensitive Recording Material) A solution of 30 parts by weight of crystal violet lactone dispersed in 200 parts by weight of polyvinyl alcohol of 10% by weight with an average particle size of about 1 μm as a reaction color developing dye solution, and bisphenol A30 as a developer. A solution prepared by dispersing 200 parts by weight of 10 parts by weight of polyvinyl alcohol in an amount of about 1 μm in average particle size was mixed at a ratio of 1:20 to obtain this recording material solution.

(Recording medium) Irreversible thermosensitive recording material solution 20
A recording layer solution was prepared by mixing and dispersing 0 part by weight of 30 parts by weight of the reversible thermosensitive recording material microcapsules. A dry film thickness of about 20 was formed on a 100 μm-thick polyethylene terephthalate sheet on which a vapor-deposited aluminum film was formed using this solution as a reflection layer.
The coating was performed with a thickness of μm to obtain a recording layer. Further, a UV-curable acrylic resin as a wear-resistant surface protective layer was coated on the recording layer by 3 μm to obtain a recording medium.

Regarding the recording temperature characteristics of this heat-sensitive recording medium, the transparency temperature region is about 68 to 90 ° C., the width is about 22 ° C., the reversible recording which becomes cloudy at 90 ° C. or more is possible, and the color development start temperature is about 100. Color develops from ℃ to blue and saturates at about 150 ℃ to enable irreversible recording. When the recording medium is erased at 80 ° C. and reversibly recorded at 95 ° C. by using a thermal head,
Clearly, the display disappeared due to transparency and the character information display due to cloudiness was observed. Furthermore, when irreversible recording was performed at 140 ° C., the reversible thermosensitive recording material was clouded and simultaneously the irreversible thermosensitive recording material was colored to display clear blue character information.

Further, the display by this irreversible recording could be well preserved in the subsequent repeated reversible thermosensitive recording.

(Example 4) Organic crystal particles of a reversible thermosensitive recording material were microencapsulated using a matrix polymer as an encapsulating material to form a recording medium of the third constitution.

(Reversible thermosensitive recording material) As organic crystal particles, 5 parts by weight of eicosane diacid and 5 parts by weight of stearic acid amide were mixed and dissolved in 400 parts by weight of tetrahydrofuran to give about 9 parts.
The particles were atomized by a spray drying method using hot air at 0 ° C. Among them, particles having an average particle size of 20 to 30 μm are dispersed as a matrix polymer in a polymer solution in which a vinyl chloride / vinyl acetate / maleic acid copolymer is dissolved in chloroform.
After crushing to an average particle size of 1 to 3 μm, a microcapsule having an average particle size of about 5 μm was obtained by an in-liquid drying method.

(Irreversible Thermosensitive Recording Material) Irreversible thermosensitive recording was carried out in the same manner as in Example 2 except that a reaction-decolorable dye which was colored red with rhodamine lactam and p-oxybenzoic acid, and dodecylamine were used as a decolorizing agent. A material solution was obtained.

(Recording medium) 120 μm as a supporting substrate
About 50 on white polyethylene terephthalate sheet
A sheet having a barium ferrite magnetic recording layer of μm and an aluminum vapor deposition layer was used. Irreversible thermosensitive recording material solution 20
A recording layer solution was prepared by mixing and dispersing 0 part by weight of 30 parts by weight of the reversible thermosensitive recording material microcapsules. This solution was applied onto a supporting base material sheet to give a dry film thickness of about 6 μm to obtain a recording layer. Further, a UV-curable acrylic resin was coated to a thickness of 2 μm as a wear-resistant surface protective layer on the recording layer to obtain a recording medium.

The recording temperature characteristics of this heat-sensitive recording medium are as follows: the transparency temperature range is about 75 to 110 ° C. and the width is about 35 ° C.
Reversible recording that becomes cloudy at 10 ° C. or higher is possible, and color development starts from about 130 ° C. and irreversible recording is possible by decoloring. This recording medium was further punched, processed into a card, and recording was performed using a thermal head. When heat is applied at 120 ° C with a thermal head for recording, and reversible recording is performed by applying heat at 90 ° C with a heat roller for erasing, character information display due to cloudiness and erasing of transparency can be repeatedly performed. did it. Further, irreversible recording was performed to erase the color at 140 ° C., and clear character display could be performed.

Further, the display by this irreversible recording could be well preserved in the subsequent repeated reversible thermosensitive recording.

Example 5 An irreversible heat-sensitive recording material was microencapsulated to form a recording medium having a fourth structure.

(Reversible thermosensitive recording material) 7 parts by weight of erucamide as organic crystal particles, 3 parts by weight of stearyl alcohol, and 30 parts by weight of partially saponified vinyl chloride / vinyl acetate copolymer (hydroxyl group ratio about 3%) as a matrix polymer. Parts and mixed and dissolved in 300 parts by weight of tetrahydrofuran to obtain a reversible thermosensitive recording material solution.

(Irreversible thermosensitive recording material) Leuco crystal violet as a reaction color-forming dye solution, methyl-4-hydroxybenzoate as a color developer, polyvinyl alcohol as a polymer for binding, and polyureaurethane as an encapsulating material by an interfacial polymerization method. A microcapsule dispersion solution of was obtained. The average particle size of microcapsules is about 10μ
It was m.

(Recording medium) A reversible thermosensitive recording material solution and an irreversible thermosensitive recording material microcapsule solution were mixed and dispersed, and a dry film thickness of about 10 μm was formed on a 100 μm thick polyethylene terephthalate sheet on which an aluminum vapor-deposited reflective layer was formed.
Was applied to obtain a recording layer. Further, a UV-curable acrylic resin as a wear-resistant surface protective layer was coated on the recording layer by 3 μm to obtain a recording medium.

The recording temperature characteristics of this recording medium are such that the clearing temperature region is about 60 to 80 ° C. and the width is about 20 ° C., and reversible recording that becomes cloudy at 90 ° C. or higher is possible. Also, irreversible recording,
When the color development start temperature is about 100 ° C., blue color is formed, and at about 140 ° C., the recording is performed with saturation. Stable reversible recording was possible, and irreversible recording was well preserved in the subsequent repeated reversible recording.

Example 6 A reversible thermosensitive recording material and an irreversible thermosensitive recording material were each microencapsulated to form a fifth recording medium.
A recording medium having the above structure was formed.

(Reversible Thermosensitive Recording Material) The microcapsules of Example 3 were used.

(Irreversible Thermosensitive Recording Material) The microcapsules of Example 5 were used.

(Recording medium) Microcapsules of both recording materials were dispersed in a polyvinyl alcohol aqueous solution so that the ratio of each microcapsule was 1: 1. Using the solution, a dry film thickness of about 20 was formed on a 120 μm-thick polyethylene terephthalate sheet on which an aluminum vapor-deposited reflective layer was formed.
The coating was performed with a thickness of μm to obtain a recording layer. Further, a UV-curable acrylic resin as a wear-resistant surface protective layer was coated on the recording layer by 3 μm to obtain a recording medium.

This recording temperature characteristic has a clearing temperature range of about 68 to 90 ° C. and a width of about 22 ° C. It can be clouded at 90 ° C. or higher, and the color develops from about 100 ° C. to blue and is saturated at about 140 ° C. To do. This recording medium is heated to 80 ° C using a heat-sensitive roller.
When reversible recording was performed at 95 ° C. using a thermal head, clear erasure of the display due to transparency and clear display of character information due to cloudiness were observed. Further, when irreversible recording was performed using a thermosensitive head to develop color at 140 ° C., the irreversible thermosensitive recording material was colored at the same time as clouding of the reversible thermosensitive recording material, and clear blue character information could be displayed.

The display by this irreversible recording could be well preserved in the subsequent repeated reversible thermosensitive recording.

[0089]

INDUSTRIAL APPLICABILITY As described above, the present invention comprises organic crystal particles having a hydrogen-bonding group and a matrix polymer having a hydrogen-bonding group, and the transparency is reversibly changed by heating and cooling the organic crystal particles. Since the reversible thermosensitive recording material and the irreversible thermosensitive recording material that exhibits color development or decolorization upon heating are thermosensitive recording media having a recording layer separated by a resin wall, the reversible thermosensitive recording material and recording characteristics By configuring the irreversible heat-sensitive recording material adjusted with the recording layer through the resin wall, it has a one-time recordable irreversible display function and the information protection and fraud prevention function by the display, so that trouble prevention and credit can be prevented. It is effective for visual confirmation. As described above, the present invention has great industrial value.

[Brief description of drawings]

FIG. 1 is a conceptual sectional view showing the structure of an embodiment of a thermal recording medium of the present invention.

FIG. 2 is a configuration diagram of a recording medium having another configuration of the thermal recording medium of the present invention.

FIG. 3 is a configuration diagram of a recording medium according to another configuration of the present invention. FIG. 3A is a diagram showing an erased state in a thermal recording medium according to an embodiment of the present invention. FIG. 3B is a thermal recording according to an embodiment of the present invention. FIG. 3C is a diagram showing a reversible recording state in the medium, and FIG. 7C is a diagram showing an irreversible recording state in the thermal recording medium according to the embodiment of the present invention.

FIG. 4 is a configuration diagram of a recording medium in a configuration example of the present invention.

FIG. 5 is a conceptual diagram of recording characteristics of the reversible thermosensitive recording material (solid line) and the irreversible thermosensitive recording material (broken line) of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Supporting substrate 2 Reflective layer 3 Recording layer 4 Surface protective layer 5 Resin wall 6 Reversible thermosensitive recording layer (material) 6A Reversible thermosensitive recording material in transparent state 6B Reversible thermosensitive recording material in cloudy state 7 Irreversible thermosensitive recording layer (material) 8 Reaction coloring dye 8A Reaction coloring dye before coloring 8B Reaction coloring dye after coloring 9 Developer 9A Developer before reaction coloring 9B Developer after reaction coloring 10 Thermosoftening transparent polymer 11 Organic crystalline particles 12 Matrix polymer 13 Transparent base polymer

Claims (8)

[Claims] 1. A reversible thermosensitive recording material comprising organic crystal particles having a hydrogen-bonding group and a matrix polymer having a hydrogen-bonding group, wherein the organic crystal particle is reversibly changed in transparency by heating and cooling, and heating. An irreversible thermosensitive recording material exhibiting color development or color erasing by means of having a recording layer separated by a resin wall. 2. An irreversible thermosensitive recording material comprising a reaction color-forming dye composed of a leuco compound as a main component and a color developer, and the color formation starting temperature of the irreversible thermosensitive recording material is higher than the clearing temperature range of the reversible thermosensitive recording material. An irreversible thermosensitive recording layer composed of the irreversible thermosensitive recording material having a color development start temperature of 90 ° C or higher at a temperature of 10 ° C or higher and composed of the reversible thermosensitive recording material is formed on the reversible thermosensitive recording material via a resin wall. The heat-sensitive recording medium according to claim 1, further comprising a recording layer that is laminated and configured separately. 3. An irreversible thermosensitive recording material containing a reaction decolorizable dye composed of a leuco compound and a decolorizing agent as main components, the decolorization starting temperature of the irreversible thermosensitive recording material being higher than the clearing temperature range of the reversible thermosensitive recording material. Has a decolorization start temperature of 90 ° C. or higher at a temperature of 10 ° C. or higher, and a reversible thermosensitive recording layer made of the reversible thermosensitive recording material through a resin wall on the irreversible thermosensitive recording layer made of the irreversible thermosensitive recording material. The heat-sensitive recording medium according to claim 1, further comprising a recording layer in which recording layers are laminated and configured separately. 4. The heat-sensitive recording medium according to claim 1, wherein at least one of the reversible heat-sensitive recording material and the irreversible heat-sensitive recording material is microencapsulated, and the encapsulating material is separated as a resin wall. 5. The thickness of the recording layer is close to at least one of the size of a microencapsulated reversible thermosensitive recording material capsule and the size of a microencapsulated irreversible thermosensitive recording material. The thermal recording medium according to claim 4. 6. A microcapsule having, as a core, one of a reversible thermosensitive recording material and an irreversible thermosensitive recording material, and mixed and dispersed in the other irreversible thermosensitive recording material or the reversible thermosensitive recording material with the encapsulating material as a resin wall. The thermal recording medium according to claim 4 or 5, characterized in that 7. A microcapsule of a reversible thermosensitive recording material,
7. The heat-sensitive recording medium according to claim 4, wherein the organic crystal particles serve as a core and the matrix polymer serves as an encapsulant. 8. A reversible thermosensitive recording material comprising organic crystal particles having a hydrogen-bonding group and a matrix polymer having a hydrogen-bonding group, the transparency being reversibly changed by heating and cooling the organic crystal particle. An irreversible thermosensitive recording material that exhibits either color development or decolorization by heating, in a thermosensitive recording medium having a recording layer separated by a resin wall, is made transparent at a temperature in the transparency temperature region of the reversible thermosensitive recording material. , Heating to a temperature range from the upper limit temperature of the transparentizing temperature region of the reversible thermosensitive recording material to the start temperature of either coloring or erasing of the irreversible thermosensitive recording material to make it opaque and reversible recording on the reversible thermosensitive recording material. Irreversible recording is carried out by heating the irreversible thermosensitive recording material to a temperature not lower than the starting temperature of either coloring or erasing. Recording method.