JP4746401B2 - Reversible thermosensitive recording medium, reversible thermosensitive recording label, reversible thermosensitive recording member, image processing apparatus and image processing method - Google Patents

Description

  The present invention relates to a reversible thermosensitive recording medium capable of forming and erasing a color image by controlling the thermal energy using a color reaction between an electron donating color-forming compound and an electron accepting compound, and The present invention relates to a reversible thermosensitive recording label using a reversible thermosensitive recording medium, a reversible thermosensitive recording member, an image processing apparatus, and an image processing method.

  Conventionally, a color development reaction between an electron donating color developing compound (hereinafter sometimes referred to as “coloring agent”) and an electron accepting compound (hereinafter also referred to as “color developing agent”) has been utilized. Thermal recording media are widely known. With the progress of OA, such heat-sensitive recording media are used as output of electronic computers, facsimiles, automatic ticket vending machines, scientific measuring instrument printers, medical measuring printers, magnetic thermosensitive cards such as prepaid cards and point cards, etc. Widely used.

  However, the heat-sensitive recording medium is irreversible and is discarded after being used once. Therefore, in recent years, from the viewpoint of recycling, various types of heat-sensitive recording media using a color development reaction between a color former and a developer that can reversibly develop and decolorize have been proposed. For example, Patent Document 1 proposes a thermal recording medium using a combination of gallic acid and phloroglucinol as a developer. In this proposal, a colored body obtained by thermal coloring is decolored with water or water vapor. However, the heat-sensitive recording medium has problems in that it is difficult to make it water-resistant, and also has a problem in record storage stability, and further, there is a problem that a decoloring device for decoloring a colored body becomes large. Patent Document 2 proposes a rewritable recording medium using a compound such as phenolphthalene, thymolphthalene, or bisphenol as a developer. According to this proposal, the color medium can be formed by heating and removing the recording medium. On the other hand, the color medium can be decolored by heating to a temperature once higher than the color density and then cooling. However, in this proposed recording medium, the process of color development and color erasure is complicated, and the color erasure obtained by erasing the color development is still somewhat colored, and a color image with good contrast can be obtained. There is a problem that cannot be obtained.

  Patent Document 3, Patent Document 4, and Patent Document 5 propose a color memory printed material containing a homogeneous solution of a color former, a developer, and a carboxylic acid ester. These proposals show a completely colored state at low temperatures and a completely decolored state at high temperatures, and can maintain a colored or decolored state at an intermediate temperature between them. White character (decolored body) can be recorded on the body. However, in the case of these recording media, since the recorded image is a negative image, its use is limited and it is necessary to keep the image within a specific temperature range in order to store the recorded image. There is.

  Patent Document 6 and Patent Document 7 each propose a reversible thermosensitive recording medium using a salt of gallic acid and a higher fatty acid that reversibly develop and reduce color as a developer. Yes. According to these recording media, it is possible to perform color development in a specific temperature range and to erase the color by heating at a higher temperature. However, in these proposals, since the color developing action and the color reducing action occur competitively, it is difficult to control these actions thermally, and it is difficult to obtain a good image contrast. .

  As described above, the conventional reversible thermosensitive recording medium utilizing the reaction between the color former and the developer has various problems and is insufficient in practice. In particular, it is quite insufficient as a multicolor reversible thermosensitive recording medium.

  Therefore, the present inventors have already made use of the electron-donating color-forming compound and the electron-accepting compound to temporarily heat the mixture to a temperature lower than the melting temperature. A reversible thermochromic composition has been proposed that takes a decolored state obtained by separating and crystallizing an electron-accepting compound by temporary heating (see Patent Document 8). According to this proposal, the above-mentioned problems can be solved, and coloring and erasing can be easily performed only by heating, and the coloring and erasing states can be stably maintained at room temperature. However, the reversible thermochromic composition is not necessarily stable to light, and when the reversible thermosensitive recording medium in a colored state is irradiated with light, the background portion is discolored or recolored. There is a problem that the decolorization by heating is not reduced to the same level as the background and the decoloration is insufficient.

  Therefore, a reversible thermosensitive recording medium and its related technology, which have excellent light resistance, can obtain a stable colored state and a decolored state with little unerased light even when exposed to light, and can stably repeat coloring and erasing, and related technologies have not been developed yet. The current situation is that it is not obtained and its prompt provision is desired.

Japanese Patent Laid-Open No. 60-193691 Japanese Patent Laid-Open No. Sho 61-237684 JP-A-62-140881 JP-A-62-138568 JP-A-62-138556 JP-A-2-188294 JP-A-2-188293 JP-A-5-124360

  An object of the present invention is to solve the conventional problems in response to the above-mentioned demands and achieve the following object. That is, the present invention provides a reversible thermosensitive recording medium with improved light resistance, a stable colored state and a decolored state with little unerased even by light irradiation, and capable of stably repeating coloring and erasing, and An object of the present invention is to provide a reversible thermosensitive recording label, a reversible thermosensitive recording member, an image processing apparatus and an image processing method using the reversible thermosensitive recording medium.

Means for solving the problems are as follows. That is,
<1> A support and at least a heat-sensitive layer on the support, the heat-sensitive layer contains an electron-donating color-forming compound and an electron-accepting compound, and the color tone is reversible depending on temperature. The reversible thermosensitive recording medium is characterized in that the thermosensitive layer contains a phenolic antioxidant containing a sulfur atom having an alkyl group on one side.
<2> The <1> according to <1>, wherein the phenol-based antioxidant containing a sulfur atom having an alkyl group on one side is a compound represented by any one of the following structural formula (1) and the following structural formula (2). It is a reversible thermosensitive recording medium.
However, in the structural formulas (1) and (2), R ¹ and R ² may be the same as or different from each other, and represent an alkyl group.
<3> The reversible thermosensitive material according to any one of <1> to <2>, wherein the content of the phenol-based antioxidant containing a sulfur atom having an alkyl group on one side is 1 to 10% by mass. It is a recording medium.
<4> The reversible thermosensitive recording medium according to any one of <1> to <3>, wherein the electron-accepting compound is a phenol compound represented by the following structural formula (3).
However, in said structural formula (3), X and Y represent the bivalent organic group containing a hetero atom. R ³ represents a divalent hydrocarbon group which may have a substituent. R ⁴ represents a monovalent hydrocarbon group which may have a substituent. n represents an integer of 1 to 3, m represents an integer of 1 to 20, and r represents an integer of 0 to 3.
<5> The reversible thermosensitive recording medium according to any one of <1> to <4>, further including a polymer-containing layer having an ultraviolet absorbing structure on the thermosensitive layer.
<6> The reversible thermosensitive recording medium according to <5>, wherein the polymer in the polymer-containing layer having an ultraviolet absorbing structure is crosslinked.
<7> The reversible thermosensitive recording medium according to any one of <1> to <6>, wherein the reversible thermosensitive recording medium contains an ultraviolet absorber.
<8> The reversible thermosensitive recording medium according to <7>, wherein the polymer-containing layer having an ultraviolet absorbing structure contains an ultraviolet absorber.
<9> The reversible thermosensitive recording medium according to any one of <1> to <8>, wherein an under layer is provided between the thermosensitive layer and the support.
<10> The reversible thermosensitive recording medium according to <9>, wherein the under layer contains hollow particles.
<11> The reversible thermosensitive recording medium according to any one of <1> to <10>, wherein the reversible thermosensitive recording medium is in the form of a card, a label, a sheet, or a roll.
<12> The aforementioned <1> which has at least one of irreversible visible information and a printable part on at least a part of at least one of the image forming surface and the surface opposite to the image forming surface of the reversible thermosensitive recording medium. The reversible thermosensitive recording medium according to any one of <1> to <11>.
<13> The reversible thermosensitive recording medium according to any one of <1> to <12>, wherein the reversible thermosensitive recording medium has either an adhesive layer or a pressure-sensitive adhesive layer on a surface opposite to an image forming surface. It is a reversible thermosensitive recording label.
<14> A reversible thermosensitive recording medium comprising an information storage unit and a reversible display unit, wherein the reversible display unit includes the reversible thermosensitive recording medium according to any one of <1> to <12>. It is a recording member.
<15> The reversible thermosensitive recording member according to <14>, wherein the information storage unit and the reversible display unit are integrated.
<16> From the above <14> to <15, wherein the information recording unit is any one selected from a magnetic thermosensitive layer, a magnetic stripe, an IC memory, an optical memory, a hologram, an RF-ID tag card, a disk, a disk cartridge, and a tape cassette. The reversible thermosensitive recording member according to any one of the above.
<17> Image forming means for heating a reversible thermosensitive recording medium to form an image on the reversible thermosensitive recording medium, and erasing an image formed on the reversible thermosensitive recording medium by heating the reversible thermosensitive recording medium An image processing apparatus comprising: the reversible thermosensitive recording medium according to any one of <1> to <12>, wherein the reversible thermosensitive recording medium includes at least one of image erasing units that perform the above operation. It is.
<18> The image processing apparatus according to <17>, wherein the image forming unit is any one of a thermal head and a laser irradiation apparatus.
<19> The image processing according to any one of <17> to <18>, wherein the image erasing unit is any one selected from a thermal head, a ceramic heater, a heat roll, a hot stamp, a heat block, and a laser irradiation device. Device.
<20> An image forming step of heating the reversible thermosensitive recording medium to form an image on the reversible thermosensitive recording medium, and an image formed on the reversible thermosensitive recording medium by heating the reversible thermosensitive recording medium. An image processing method comprising at least one of image erasing steps to be erased, wherein the reversible thermosensitive recording medium is the reversible thermosensitive recording medium according to any one of <1> to <12>. .
<21> The image processing method according to <20>, wherein the image is formed using either a thermal head or a laser irradiation apparatus.
<22> The image may be erased using any one selected from a thermal head, a ceramic heater, a heat roll, a hot stamp, a heat block, and a laser irradiation device. This is an image processing method.
<23> The image processing method according to any one of <21> to <22>, including a step of forming a new image while erasing an image using a thermal head.

  The reversible thermosensitive recording medium of the present invention comprises a support and at least a thermosensitive layer on the support, and the thermosensitive layer contains an electron-donating color-forming compound and an electron-accepting compound, and depends on temperature. Thus, the color tone reversibly changes, and the heat-sensitive layer contains a phenol-based antioxidant containing a sulfur atom having an alkyl group on one side. In the reversible thermosensitive recording medium of the present invention, since the thermosensitive layer contains a phenolic antioxidant containing a sulfur atom having an alkyl group on one side, the light resistance is improved and stable even when exposed to light. A colored state and a decolored state with little unerased can be obtained, and repetition of coloring and decoloring can be performed stably.

  The reversible thermosensitive recording label of the present invention has either an adhesive layer or a pressure-sensitive adhesive layer on the surface opposite to the image forming surface of the reversible thermosensitive recording medium of the present invention. The reversible thermosensitive recording label has improved light resistance, good color density, high-speed erasing with a thermal head, little erasure due to repeated printing, and excellent printed portion durability. Moreover, since it has any one of the adhesive layer and the pressure-sensitive adhesive layer, it is difficult to directly apply the heat-sensitive layer, a thick substrate such as a card made of vinyl chloride with a magnetic stripe, a container having a sheet size larger than the card size , Stickers, large screens, etc.

  The reversible thermosensitive recording member of the present invention has an information storage unit and a reversible display unit, and the reversible display unit is the reversible thermosensitive recording medium of the present invention. In the reversible thermosensitive recording member, in the reversible display portion, the thermosensitive layer contains a phenolic antioxidant containing a sulfur atom having an alkyl group on one side, so that it is excellent in light resistance and has no erasure residue due to repeated printing. The durability of the printed part can be remarkably improved. And an image excellent in contrast, visibility, etc. is formed. On the other hand, in the information recording part, character information, image information, and recording information according to the type of magnetic thermosensitive layer, magnetic stripe, IC memory, optical memory, RF-ID tag card, disk, disk cartridge, tape cassette, hologram, etc. Desired information such as music information and video information is recorded and erased.

  The image processing apparatus of the present invention includes at least one of an image forming unit for heating the reversible thermosensitive recording medium of the present invention to form an image and an image erasing unit for erasing the image. In the image processing apparatus, the image forming unit heats the reversible thermosensitive recording medium of the present invention to form an image on the reversible thermosensitive recording medium. On the other hand, the image erasing means erases the image formed on the reversible thermosensitive recording medium by heating the reversible thermosensitive recording medium of the present invention. In the present invention, since the reversible thermosensitive recording medium of the present invention is used as the reversible thermosensitive recording medium, it is excellent in light resistance, has little erasure residue due to repeated printing, and can be rewritten and recorded with high practicality. .

  In the image processing method of the present invention, the reversible thermosensitive recording medium of the present invention is heated to perform at least one of image formation and image erasure. In the image processing method, the reversible thermosensitive recording medium of the present invention is heated to form an image on the reversible thermosensitive recording medium. On the other hand, the reversible thermosensitive recording medium of the present invention is heated to erase the image formed on the reversible thermosensitive recording medium. In the present invention, since the reversible thermosensitive recording medium of the present invention is used as the reversible thermosensitive recording medium, it has excellent light resistance, little erasure remains due to repeated printing, and background stains, cracks, and dents occur. Therefore, an image with a high color density can be formed.

  According to the present invention, conventional problems can be solved, light resistance is excellent, a stable colored state and a decolored state with little unerased are obtained even when exposed to light, and repetition of coloring and erasing is stable. A reversible thermosensitive recording medium, a reversible thermosensitive recording label, a reversible thermosensitive recording member, an image processing apparatus, and an image processing method using the reversible thermosensitive recording medium are provided.

(Reversible thermosensitive recording medium)
The reversible thermosensitive recording medium of the present invention comprises a support, at least a thermosensitive layer on the support, a polymer-containing layer having an ultraviolet absorption structure, an under layer, an intermediate layer, and, if necessary, other layers. Having a layer.

<Thermosensitive layer>
The heat-sensitive layer contains an electron-donating color-forming compound, an electron-accepting compound, and a phenolic antioxidant containing a sulfur atom having an alkyl group on one side, a binder resin, and other components as necessary. It contains.

  The unerased residue at the time of erasing the image forming portion by light irradiation in the heat-sensitive layer is caused by deteriorating the electron-donating color-forming compound in the reversible thermochromic composition by oxygen in the air becoming an oxidizing agent by light irradiation. This is due to the occurrence of defective erasure by changing to an irreversible substance. Therefore, in the present invention, a phenolic antioxidant containing a sulfur atom having an alkyl group on one side is added to the reversible thermochromic composition constituting the thermosensitive layer.

  Examples of the antioxidant include phenol-based antioxidants, amine-based antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants. Among these, a phenol-based antioxidant containing sulfur is preferable because it has a high effect of suppressing a reaction in which the electron-donating colored compound is decomposed by light irradiation, and a phenol-based one containing a sulfur atom having an alkyl group on one side. Antioxidants are used in the present invention because they are extremely effective.

The phenolic antioxidant containing a sulfur atom having an alkyl group on one side is a phenolic antioxidant containing sulfur, one of the substituents on both sides of the sulfur atom is an alkyl group, and the other is other than an alkyl group Is a substituent of The same applies when two or more sulfur atoms are contained.
There is no restriction | limiting in particular as said alkyl group, Although it can select suitably according to the objective, C1-C12 is preferable, 1-10 are more preferable, and any of linear, branched, and cyclic | annular There may be. Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group. Group, and the like. The alkyl group may be further substituted with a substituent, and examples of the substituent include a fluorine atom, a cyano group, a phenyl group, and a halogen atom.

As the phenol-based antioxidant containing a sulfur atom having an alkyl group on one side, a compound represented by either the following structural formula (1) or structural formula (2) is suitable.
However, in the structural formulas (1) and (2), R ¹ and R ² may be the same as or different from each other, and represent an alkyl group.

The alkyl group of R ¹ and R ² has the same meaning as the alkyl group described above, and among these, a hexyl group, a heptyl group, an octyl group, and a nonyl group are particularly preferable.

  Therefore, even if it is a sulfur containing phenolic antioxidant, what does not contain the sulfur atom which has an alkyl group on one side does not correspond to the antioxidant of this invention. That is, 4,4-thiobis (3-methyl-6-tert-butylphenol) represented by the following structural formula A, 2,2-thio-diethylenebis [3- (3,5 represented by the following structural formula B -Di-t-butyl-4-hydroxyphenyl) propionate] is not a phenolic antioxidant containing a sulfur atom with an alkyl group on one side, and is not included in the antioxidant of the present invention.

  Examples of the phenol-based antioxidant containing a sulfur atom having an alkyl group on one side include 2,4-bis- (n-octylthio) -6- (4-hydroxy-3, represented by the following structural formula C: Preferable examples include 5-di-t-butylanilino) -1,3,5-triazine, 2,4-bis [(octylthio) methyl] -o-cresol represented by the following structural formula D, and the like.

As the phenol-based antioxidant containing a sulfur atom having an alkyl group on one side, an appropriately synthesized product or a commercially available product may be used.
Preferred examples of the commercially available products include trade names “IRGANOX1520L” and “IRGANOX565” manufactured by Ciba Specialty Chemicals.

  There is no restriction | limiting in particular in content in the said thermosensitive layer of the phenolic antioxidant containing the sulfur atom which has the alkyl group on the one side, According to the objective, 1-10 mass% is preferable, and 2 -8 mass% is more preferable. When the content is less than 1% by mass, the antioxidant function is lowered, so that the degradation of the dye by light cannot be suppressed and the dye itself is colored, resulting in a decrease in the erasing function. If the amount exceeds 10% by mass, background fogging may occur, and the whiteness of the background may be impaired before image formation.

The heat-sensitive layer contains an electron-donating color-forming compound and an electron-accepting compound, and the color tone reversibly changes depending on the temperature.
“The color tone reversibly changes depending on temperature” in the heat-sensitive layer means a phenomenon in which a visible change is reversibly caused by a temperature change, and is relative to the difference in heating temperature and cooling rate after heating. This means that a colored state and a decolored state can be formed. In this case, the visible change can be divided into a change in color state and a change in shape, but in the present invention, a material that mainly causes a change in color state is used. The change in the color state includes changes in transmittance, reflectance, absorption wavelength, scattering degree, and the like, and an actual reversible thermosensitive recording material displays by a combination of these changes. More specifically, there is no particular limitation as long as the transparency and color tone are reversibly changed by heat, and it can be appropriately selected according to the purpose. For example, the first specific temperature higher than room temperature is the first. And a second color temperature that is higher than the first specific temperature and then cooled to become the second color state. Among these, those in which the color state changes between the first specific temperature and the second specific temperature are particularly preferable.

  Examples of these include a transparent state at the first specific temperature and a cloudy state at the second specific temperature (Japanese Patent Application Laid-Open No. 55-154198), coloring at the second specific temperature, Those which are decolored at a specific temperature (JP-A-4-224996, JP-A-4-247985, JP-A-4-267190, etc.), become cloudy at the first specific temperature, and at the second specific temperature Those that are in a transparent state (Japanese Patent Laid-Open No. 3-169590, etc.), those that develop black, red, blue, etc. at a first specific temperature and decolorize at a second specific temperature (Japanese Patent Laid-Open No. 2-188293) JP, 2-188294, A) etc. are mentioned.

  The reversible thermosensitive recording medium of the present invention can form a relatively colored state and a decolored state depending on at least one of the heating temperature and the cooling rate after heating. Here, the basic coloring and decoloring phenomenon of the composition comprising the color former and the developer will be described. FIG. 1 shows the relationship between the color density and temperature of this reversible thermosensitive recording medium. When the temperature of the recording medium initially in the decolored state (A) is raised, color development occurs at the temperature T1 at which melting starts, and the molten color state (B) is obtained. When rapidly cooled from the melt color state (B), the color state can be lowered to room temperature and a solid color state (C) is obtained. Whether or not this color development state is obtained depends on the rate of temperature decrease from the molten state, and in slow cooling, the color disappears during the temperature decrease, and the same color disappearance state (A) or rapid color development state (C ) A relatively low concentration state is formed. On the other hand, when the temperature of the rapid color development state (C) is raised again, decoloration occurs at a temperature T2 lower than the color development temperature (D to E), and when the temperature is lowered from here, the same color disappearance state (A) is restored. The actual color developing temperature and color erasing temperature vary depending on the combination of the developer and color former used, and can be selected according to the purpose. Further, the density of the melt coloring state and the coloring density when rapidly cooled are not necessarily the same and may be different.

  In the reversible thermosensitive recording medium, the color development state (C) obtained by quenching from the melted state is a state in which the developer and the color former are mixed in a state where they can contact each other and are in a solid state. Is often formed. This state is a state where the developer and the color former are aggregated to maintain the color development, and it is considered that the color development is stabilized by the formation of this aggregated structure. On the other hand, the decolored state is a state in which both phases are separated. This state is a state in which molecules of at least one compound aggregate to form a domain or crystallize, and the color former and the developer are separated and stabilized by aggregation or crystallization. Conceivable. In many cases, more complete color erasure occurs due to phase separation of the two and crystallization of the developer. In both the decolorization by slow cooling from the melted state shown in FIG. 1 and the decoloration by heating from the colored state, the aggregation structure changes at this temperature, and phase separation and crystallization of the developer occur.

  In the reversible thermosensitive recording medium of the present invention, color recording may be formed by heating to a temperature at which it is once melt-mixed by a thermal head or the like and then rapidly cooling. Further, decolorization is two methods, a method of slowly cooling from a heated state and a method of heating to a temperature slightly lower than the coloring temperature. However, they are the same in the sense that they are phase-separated or at least temporarily held at a temperature at which one crystallizes. The reason for rapid cooling in the formation of the colored state is to prevent the temperature from being maintained at this phase separation temperature or crystallization temperature. The rapid cooling and slow cooling here are relative to one composition, and the boundary thereof changes depending on the combination of the color former and the developer.

-Electron-accepting compound-
The electron-accepting compound (developer) is not particularly limited as long as it can reversibly develop and decolorize using heat as a factor, and can be appropriately selected according to the purpose. (I) a structure having a color developing ability (for example, phenolic hydroxyl group, carboxylic acid group, phosphoric acid group, etc.) that develops an electron donating color developing compound (color developing agent), and (ii) controlling cohesion between molecules. A compound having one or more structures in the molecule selected from the following structures (for example, a structure in which long-chain hydrocarbon groups are linked) is preferable. In addition, the linking part may be through a divalent or higher valent linking group containing a hetero atom, and the long chain hydrocarbon group contains at least one of the same linking group and aromatic group. Also good. Among these, a phenol compound represented by the following structural formula (3) and a phenol compound represented by the following structural formula (4) are particularly preferable.

However, in said structural formula (3), X and Y represent the bivalent organic group containing a hetero atom. R ³ represents a divalent hydrocarbon group which may have a substituent. R ⁴ represents a monovalent hydrocarbon group which may have a substituent. n represents an integer of 1 to 3, m represents an integer of 1 to 20, and r represents an integer of 0 to 3.

However, in said Structural Formula (4), n represents the integer of 1-3. X represents a divalent organic group containing a hetero atom. R ³ represents a divalent hydrocarbon group which may have a substituent. R ⁴ represents a monovalent hydrocarbon group which may have a substituent.

R ³ in the structural formulas (3) and (4) represents a C 1-20 divalent hydrocarbon group which may be substituted with a substituent.
Preferred examples of R ³ include those shown below.

However, q, q ′, q ″, and q ′ ″ in the above formulas each represent an integer that satisfies the carbon number of R ³ . Among them, - _{(CH 2) q} - are particularly preferred.

R ⁴ in the structural formulas (3) and (4) represents an aliphatic hydrocarbon group having 1 to 24 carbon atoms which may be substituted with a substituent, and preferably 8 to 18 carbon atoms.
The aliphatic hydrocarbon group may be linear or branched, and may have an unsaturated bond. Examples of the substituent bonded to the hydrocarbon group include a hydroxyl group, a halogen atom, and an alkoxy group. Note that when the sum of carbons of R ³ and R ⁴ is 7 or less, the stability of color development and decoloring properties are lowered, and therefore the number of carbons is preferably 8 or more, and more preferably 11 or more.
Preferred examples of R ⁴ include the following.
However, q, q ′, q ″, and q ′ ″ in the above formulas each represent an integer that satisfies the carbon number of R ⁴ . Among these, — (CH ₂ ) _q —CH ₃ is particularly preferable.

X and Y in the structural formulas (3) and (4) represent a divalent organic group containing a hetero atom, and particularly a divalent organic group containing a nitrogen atom or an oxygen atom is preferable. It represents a divalent organic group having at least one group represented.

Preferred examples of the divalent organic group include groups represented by the following structural formulas.

Among these, particularly preferred groups include those represented by the following structural formula.

Examples of the phenol compound represented by the structural formula (3) include compounds represented by the following structural formulas (3-1) to (3-4).
However, in the structural formulas (3-1) to (3-4), q, q ′, q ″, and s each independently represent an integer of 0 to 20, and the sum of these integers is 8 or more. is there. Y, Y ′, and Y ″ represent a divalent organic group containing a hetero atom, and these may be the same or different.

  Specific examples of the phenol compound represented by the structural formula (3) include compounds shown in Table 1 below as examples of the structural formula (3-1) and the structural formula (3-2). Although not shown in the structural formula here, in the case of the compounds represented by the structural formulas (3-3) and (3-4), X and Y are the same as those shown in Table 1 below. Take as an example. However, it is not limited to these.

As a phenol compound represented by the said Structural formula (4), either the following structural formula (4-1) and the following structural formula (4-2) is mentioned suitably, for example.
However, m represents 5-11 in the said Structural formula (4-1) and (4-2). n represents 8-22.

  Specific examples of the phenol compound represented by the structural formula (4-1) and the structural formula (4-2) are shown below.

-Electron donating color compound-
There is no restriction | limiting in particular as said electron donating coloring compound (color former), According to the objective, it can select suitably, For example, a leuco dye etc. are mentioned suitably.

  As the leuco dye, a fluorane compound and an azaphthalide compound are suitable. For example, 2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-di (n-butylamino) fluorane 2-anilino-3-methyl-6- (Nn-propyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (N-isopropyl-N-methylamino) fluorane, 2-anilino -3-methyl-6- (N-isobutyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (Nn-amyl-N-methylamino) fluorane, 2-anilino-3-methyl -6- (N-sec-butyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (Nn-amyl-N-ethylamino) Luolan, 2-anilino-3-methyl-6- (N-iso-amyl-N-ethylamino) fluorane, 2-anilino-3-methyl-6- (Nn-propyl-N-isopropylamino) fluorane, 2-anilino-3-methyl-6- (N-cyclohexyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (N-ethyl-p-toluidino) fluorane, 2-anilino-3-methyl -6- (N-methyl-p-toluidino) fluorane, 2- (m-trichloromethylanilino) -3-methyl-6-diethylaminofluorane, 2- (m-trifluoromethylanilino) -3-methyl -6-diethylaminofluorane, 2- (m-trichloromethylanilino) -3-methyl-6- (N-cyclohexyl-N-methylamino) fluor Lan, 2- (2,4-dimethylanilino) -3-methyl-6-diethylaminofluorane, 2- (N-ethyl-p-toluidino) -3-methyl-6- (N-ethylanilino) fluorane, 2 -(N-ethyl-p-toluidino) -3-methyl-6- (N-propyl-p-toluidino) fluorane, 2-anilino-6- (Nn-hexyl-N-ethylamino) fluorane, 2- (O-chloroanilino) -6-diethylaminofluorane, 2- (o-chloroanilino) -6-dibutylaminofluorane, 2- (m-trifluoromethylanilino) -6-diethylaminofluorane, 2,3-dimethyl -6-dimethylaminofluorane, 3-methyl-6- (N-ethyl-p-toluidino) fluorane, 2-chloro-6-diethylaminofluorane, 2 -Bromo-6-diethylaminofluorane, 2-chloro-6-dipropylaminofluorane, 3-chloro-6-cyclohexylaminofluorane, 3-bromo-6-cyclohexylaminofluorane, 2-chloro-6- ( N-ethyl-N-isoamylamino) fluorane, 2-chloro-3-methyl-6-diethylaminofluorane, 2-anilino-3-chloro-6-diethylaminofluorane, 2- (o-chloroanilino) -3-chloro -6-cyclohexylaminofluorane, 2- (m-trifluoromethylanilino) -3-chloro-6-diethylaminofluorane, 2- (2,3-dichloroanilino) -3-chloro-6-diethylaminofluor Oran, 1,2-benzo-6-diethylaminofluorane, 3-diethylamino-6- (m-tri (Loromethylanilino) fluorane, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-) Methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-octyl-2-methylindol-3-yl) -3- (2-ethoxy-4) -Diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-methyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl- 2-Methylindol-3-yl) -3- (2-methyl-4-diethylaminophenyl) -7-azaphthalide, 3- (1-ethyl-2-methylindo) Ru-3-yl) -3- (4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-Nn-amyl-N- Methylaminophenyl) -4-azaphthalide, 3- (1-methyl-2-methylindol-3-yl) -3- (2-hexyloxy-4-diethylaminophenyl) -4-azaphthalide, 3,3-bis ( 2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3,3-bis (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, and the like.

In addition to the fluorane compound and the azaphthalide compound, conventionally known leuco dyes can be used as the electron donating color-forming compound (color former). For example, 2- (p-acetylanilino) -6- (Nn-amyl-Nn-butylamino) fluorane, 2-benzylamino-6- (N-ethyl-p-toluidino) fluorane, 2-benzylamino-6- (N-methyl-2 , 4-dimethylanilino) fluorane, 2-benzylamino-6- (N-ethyl-2,4-dimethylanilino) fluorane, 2-benzylamino-6- (N-methyl-p-toluidino) fluorane, -Benzylamino-6- (N-ethyl-p-toluidino) fluorane, 2- (di-p-methylbenzylamino) -6- (N-ethyl-p-toluidino) fluora 2- (α-phenylethylamino) -6- (N-ethyl-p-toluidino) fluorane, 2-methylamino-6- (N-methylanilino) fluorane, 2-methylamino-6- (N-ethylanilino) Fluorane, 2-methylamino-6- (N-propylanilino) fluorane, 2-ethylamino-6- (N-methyl-p-toluidino) fluorane, 2-methylamino-6- (N-methyl-2, 4-dimethylanilino) fluorane, 2-ethylamino-6- (N-ethyl-2,4-dimethylanilino) fluorane, 2-dimethylamino-6- (N-methylanilino) fluorane, 2-dimethylamino-6 -(N-ethylanilino) fluorane, 2-diethylamino-6- (N-methyl-p-toluidino) fluorane, 2-diethylamino- 6- (N-ethyl-p-toluidino) fluorane, 2-dipropylamino-6- (N-methylanilino) fluorane, 2-dipropylamino-6- (N-ethylanilino) fluorane, 2-amino-6- ( N-methylanilino) fluorane, 2-amino-6- (N-ethylanilino) fluorane, 2-amino-6- (N-propylanilino) fluorane, 2-amino-6- (N-methyl-p-toluidino) fluorane 2-amino-6- (N-ethyl-p-toluidino) fluorane, 2-amino-6- (N-propyl-p-toluidino) fluorane, 2-amino-6- (N-methyl-p-ethylanilino) Fluorane, 2-amino-6- (N-ethyl-p-ethylanilino) fluorane, 2-amino-6- (N-propyl-p-ethylanily) ) Fluorane, 2-amino-6- (N-methyl-2,4-dimethylanilino) fluorane, 2-amino-6- (N-ethyl-2,4-dimethylanilino) fluorane, 2-amino-6 -(N-propyl-2,4-dimethylanilino) fluorane, 2-amino-6- (N-methyl-p-chloroanilino) fluorane, 2-amino-6- (N-ethyl-p-chloroanilino) fluorane, 2-amino-6- (N-propyl-p-chloroanilino) fluorane, 1,2-benzo-6- (N-ethyl-N-isoamylamino) fluorane, 1,2-benzo-6-dibutylaminofluorane, 1,2-benzo-6- (N-methyl-N-cyclohexylamino) fluorane, 1,2-benzo-6- (N-ethyl-N-toluidino) fluorane, etc. It is.
These may be used individually by 1 type and may use 2 or more types together. Multi-color and full-color can also be achieved by stacking layers that develop colors having different colors.

  The mixing ratio of the electron-donating color-forming compound (color former) and the electron-accepting compound (developer) varies depending on the combination of the compounds used, and cannot be specified unconditionally. The developer is preferably from 0.1 to 20, and more preferably from 0.2 to 10. If the amount of the developer is less or more than this range, the density of the colored state may be lowered, which may be a problem. In addition, the color former and the developer can be used in a microcapsule.

-Discoloration accelerator-
In the present invention, by using the developer and a compound having at least one amide group, urethane group, and urea group in the molecule as the color erasure accelerator, the color erasure is promoted in the process of forming the erased state. An intermolecular interaction is induced between the agent and the developer, and the erasing speed can be remarkably increased.

  The decoloring accelerator may be a compound having at least one selected from an amide group, a urethane group, and a urea group in the molecule, and among these, the following structural formulas (5) to (11) The compounds represented are particularly preferred.

R ⁵ —NHCO—R ^6. Structural formula (5)
^{R 5 -NHCO-R 7 -CONH-} R 6 ··· structural formula (6)
^{R 5 -CONH-R 7 -NHCO-} R 6 ··· structural formula (7)
^{R 5 -NHCOO-R} 6 ··· structural formula (8)
R < ⁵ > -NHCOO-R < ⁷ > -OCONH-R < ⁶ > ... Structural formula (9)
R ⁵ —OCONH—R ⁷ —NHCOO—R ^6. Structural formula (10)
In the Structural Formula ^{(5) ~ (11),} R 5, R 6, and ^{R 8} represents a straight-chain alkyl group having 7 to 22 carbon atoms, branched alkyl groups, unsaturated alkyl groups. R ⁷ represents a divalent organic group having 1 to 10 carbon atoms. R ⁹ represents a trivalent functional group having 4 to 10 carbon atoms.

Examples of R ⁵ , R ⁶ , and R ⁸ include a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a stearyl group, a behenyl group, and an oleyl group.
Examples of R ⁶ include a methylene group, an ethylene group, a propylene group, a butylene group, a heptamethylene group, a hexamethylene group, an octamethylene group, a —C ₃ H ₆ OC ₃ H ₆ — group, and —C ₂ H ₄ OC _2. H ₄ - _{group, -C 2 H 4 OC 2 H} 4 OC 2 H 4 - group, and the like.
Preferred examples of R ⁹ include those represented by the following structural formulas.

  Specific examples of the compounds represented by the structural formula (5) to the structural formula (11) include compounds represented by the following (1) to (81).

(1) C ₁₁ H ₂₃ CONHC ₁₂ H ₂₅ ,
(2) C ₁₅ H ₃₁ CONHC ₁₆ H ₃₃ ,
(3) C ₁₇ H ₃₅ CONHC ₁₈ H ₃₇ ,
(4) C ₁₇ H ₃₅ CONHC ₁₈ H ₃₅ ,
(5) C ₂₁ H ₄₁ CONHC ₁₈ H ₃₇ ,
(6) C ₁₅ H ₃₁ CONHC ₁₈ H ₃₇ ,
(7) C ₁₇ H ₃₅ CONHCH ₂ NHCOC ₁₇ H ₃₅ ,
(8) C ₁₁ H ₂₃ CONHCH ₂ NHCOC ₁₁ H ₂₃ ,
_{(9) C 7 H 15 CONHC} 2 H 4 NHCOC 17 H 35,
(10) C ₉ H ₁₉ CONHC ₂ H ₄ NHCOC ₉ H ₁₉ ,
(11) C ₁₁ H ₂₃ CONHC ₂ H ₄ NHCOC ₁₁ H ₂₃ ,
(12) C ₁₇ H ₃₅ CONHC ₂ H ₄ NHCOC ₁₇ H ₃₅ ,
_{(13) (CH 3) 2} CHC 14 H 35 CONHC 2 H 4 NHCOC 14 H 35 (CH 3) 2,
(14) C ₂₁ H ₄₃ CONHC ₂ H ₄ NHCOC ₂₁ H ₄₃ ,
(15) C ₁₇ H ₃₅ CONHC ₆ H ₁₂ NHCOC ₁₇ H ₃₅ ,
(16) C ₂₁ H ₄₃ CONHC ₆ H ₁₂ NHCOC ₂₁ H ₄₃ ,
(17) C ₁₇ H ₃₃ CONHCH ₂ NHCOC ₁₇ H ₃₃ ,
_{(18) C 17 H 33 CONHC} 2 H 4 NHCOC 17 H 33,
(19) C ₂₁ H ₄₁ CONHC ₂ H ₄ NHCOC ₂₁ H ₄₁ ,
_{(20) C 17 H 33 CONHC} 6 H 12 NHCOC 17 H 33,
(21) C ₈ H ₁₇ NHCOC ₂ H ₄ CONHC ₁₈ H ₃₇ ,
(22) C ₁₀ H ₂₁ NHCOC ₂ H ₄ CONHC ₁₀ H ₂₁ ,
(23) C ₁₂ H ₂₅ NHCOC ₂ H ₄ CONHC ₁₂ H ₂₅ ,
(24) C ₁₈ H ₃₇ NHCOC ₂ H ₄ CONHC ₁₈ H ₃₇ ,
(25) C ₂₁ H ₄₃ NHCOC ₂ H ₄ CONHC ₂₁ H ₄₃ ,
_{(26) C 18 H 37 NHCOC} 6 H 12 CONHC 18 H 37,
_{(27) C 18 H 35 NHCOC} 4 H 8 CONHC 18 H 35,
_{(28) C 18 H 35 NHCOC} 8 H 16 CONHC 18 H 35,
(29) C ₁₂ H ₂₅ OCONHC ₁₈ H ₃₇ ,
(30) C ₁₃ H ₂₇ OCONHC ₁₈ H ₃₇ ,
(31) C ₁₆ H ₃₃ OCONHC ₁₈ H ₃₇ ,
(32) C ₁₈ H ₃₇ OCONHC ₁₈ H ₃₇ ,
(33) C ₂₁ H ₄₃ OCONHC ₁₈ H _37,
(34) C ₁₂ H ₂₅ OCONHC ₁₆ H ₃₃ ,
(35) C ₁₃ H ₂₇ OCONHC ₁₆ H ₃₃ ,
(36) C ₁₆ H ₃₃ OCONHC ₁₆ H ₃₃ ,
(37) C ₁₈ H ₃₇ OCONHC ₁₆ H ₃₃ ,
(38) C ₂₁ H ₄₃ OCONHC ₁₆ H ₃₃ ,
(39) C ₁₂ H ₂₅ OCONHC ₁₄ H ₂₉ ,
(40) C ₁₃ H ₂₇ OCONHC ₁₄ H ₂₉ ,
(41) C ₁₆ H ₃₃ OCONHC ₁₄ H ₂₉ ,
(42) C ₁₈ H ₃₇ OCONHC ₁₄ H ₂₉ ,
(43) C ₂₂ H ₄₅ OCONHC ₁₄ H ₂₉ ,
(44) C ₁₂ H ₂₅ OCONHC ₁₂ H ₃₇ ,
(45) C ₁₃ H ₂₇ OCONHC ₁₂ H ₃₇ ,
(46) C ₁₆ H ₃₃ OCONHC ₁₂ H ₃₇ ,
(47) C ₁₈ H ₃₇ OCONHC ₁₂ H ₃₇ ,
(48) C ₂₁ H ₄₃ OCONHC ₁₂ H ₃₇ ,
(49) C ₂₂ H ₄₅ OCONHC ₁₈ H ₃₇ ,
(50) C ₁₈ H ₃₇ NHCOOC ₂ H ₄ OCONHC ₁₈ H ₃₇ ,
(51) C ₁₈ H ₃₇ NHCOOC ₃ H ₆ OCONHC ₁₈ H ₃₇ ,
(52) C ₁₈ H ₃₇ NHCOOC ₄ H ₈ OCONHC ₁₈ H ₃₇ ,
(53) C ₁₈ H ₃₇ NHCOOC ₆ H ₁₂ OCONHC ₁₈ H ₃₇ ,
(54) C ₁₈ H ₃₇ NHCOOC ₈ H ₁₆ OCONHC ₁₈ H ₃₇ ,
(55) C ₁₈ H ₃₇ NHCOOC ₂ H ₄ OC ₂ H ₄ OCONHC ₁₈ H ₃₇ ,
(56) C ₁₈ H ₃₇ NHCOOC ₃ H ₆ OC ₃ H ₆ OCONHC ₁₈ H ₃₇ ,
(57) C ₁₈ H ₃₇ NHCOOC ₁₂ H ₂₄ OCONHC ₁₈ H ₃₇ ,
(58) C ₁₈ H ₃₇ NHCOOC ₂ H ₄ OC ₂ H ₄ OC ₂ H ₄ OCONHC ₁₈ H ₃₇ ,
(59) C ₁₆ H ₃₃ NHCOOC ₂ H ₄ OCONHC ₁₆ H ₃₃ ,
(60) C ₁₆ H ₃₃ NHCOOC ₃ H ₆ OCONHC ₁₆ H ₃₃ ,
(61) C ₁₆ H ₃₃ NHCOOC ₄ H ₈ OCONHC ₁₆ H ₃₃ ,
(62) C ₁₆ H ₃₃ NHCOOC ₆ H ₁₂ OCONHC ₁₆ H ₃₃ ,
(63) C ₁₆ H ₃₃ NHCOOC ₈ H ₁₆ OCONHC ₁₆ H ₃₃ ,
(64) C ₁₈ H ₃₇ OCOHNC ₆ H ₁₂ NHCOOC ₁₈ H ₃₇ ,
(65) C ₁₆ H ₃₃ OCOHNC ₆ H ₁₂ NHCOOC ₁₆ H ₃₃ ,
_{(66) C 14 H 29 OCOHNC} 6 H 12 NHCOOC 14 H 29,
_{(67) C 12 H 25 OCOHNC} 6 H 12 NHCOOC 12 H 25,
_{(68) C 10 H 21 OCOHNC} 6 H 12 NHCOOC 10 H 21,
_{(69) C 8 H 17 OCOHNC} 6 H 12 NHCOOC 8 H 17,

  The addition amount of the decolorization accelerator is preferably 0.1 to 300 parts by mass, more preferably 3 to 100 parts by mass with respect to 100 parts by mass of the developer. When the addition amount is less than 0.1 parts by mass, the effect of adding a decoloring accelerator may not be exhibited. When the addition amount exceeds 300 parts by mass, the color density may decrease.

  In addition to the above-described components, the heat-sensitive layer may contain a binder resin and, if necessary, various additives for improving or controlling the coating characteristics and color-decoloring / decoloring characteristics of the heat-sensitive layer. Examples of the additive include a crosslinking agent, a crosslinking accelerator, a filler, a lubricant, a surfactant, a conductive agent, a filler, an antioxidant, a light stabilizer, a color stabilizer, and a plasticizer.

The binder resin is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride vinyl acetate copolymer, ethyl cellulose, polystyrene resin, and styrene copolymer. Polymer, phenoxy resin, polyester resin, aromatic polyester resin, polyurethane resin, polycarbonate resin, polyacrylate resin, polymethacrylate resin, acrylic copolymer, maleic acid copolymer, polyvinyl alcohol resin, modified Examples thereof include polyvinyl alcohol resin, hydroxyethyl cellulose, carboxymethyl cellulose, starches, and the like.
The role of these binder resins is to keep each material of the composition uniformly dispersed without being displaced by the application of heat for recording and erasing. Therefore, it is preferable to use a resin having high heat resistance as the binder resin. Further, as the binder resin, it is preferable to use a curable resin to which a cross-linking agent is added and which can be cross-linked by, for example, heat, ultraviolet light, electron beam or the like (hereinafter, sometimes referred to as “resin in a cross-linked state”). ). By containing the curable resin in the heat-sensitive layer, the heat resistance and the coating film strength of the heat-sensitive layer are improved, and the repeated durability of the reversible heat-sensitive recording medium is improved.

The curable resin is not particularly limited and may be appropriately selected depending on the intended purpose. For example, acrylic polyol resin, polyester polyol resin, polyurethane polyol resin, phenoxy resin, polyvinyl butyral resin, cellulose acetate propionate, Examples thereof include a resin having a group that reacts with a crosslinking agent such as cellulose acetate butyrate, or a resin obtained by copolymerizing a monomer having a group that reacts with a crosslinking agent and another monomer. Among these, acrylic polyol resin, polyester polyol resin, and polyurethane polyol resin are particularly preferable.
Further, the hydroxyl value of the curable resin is preferably 70 KOHmg / g or more, more preferably 90 KOHmg / g or more, from the viewpoint of improving durability, coating film surface hardness and crack resistance. The magnitude of the hydroxyl value affects the crosslink density, and therefore affects the chemical resistance and physical properties of the coating film.

  The acrylic polyol resin uses a (meth) acrylic acid ester monomer, an unsaturated monomer having a carboxylic acid group, an unsaturated monomer having a hydroxyl group, and other ethylenically unsaturated monomers. It can be synthesized according to a known solution polymerization method, suspension polymerization method, emulsion polymerization method and the like. Examples of the unsaturated monomer having a hydroxyl group include hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), 2-hydroxyethyl methacrylate (HEMA), 2-hydroxypropyl methacrylate (HPMA), and 2-hydroxybutyl. Examples include monoacrylate (2-HBA) and 1,4-hydroxybutyl monoacrylate (1-HBA). Among these, the use of a monomer having a primary hydroxyl group leads to crack resistance of the coating film. 2-Hydroxyethyl methacrylate is particularly preferred because of its good durability.

There is no restriction | limiting in particular as said crosslinking agent, According to the objective, it can select suitably from conventionally well-known isocyanate type compounds, amines, phenols, an epoxy compound, etc. Of these, isocyanate compounds are particularly suitable.
The isocyanate compound is not particularly limited and may be appropriately selected from known compounds according to the purpose. For example, a urethane modified product, an allophanate modified product, an isocyanurate modified product, a burette modified product of an isocyanate monomer. Body, carbodiimide modified body, modified body such as blocked isocyanate, and the like. Examples of the isocyanate monomer that forms the modified product include tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), naphthylene diisocyanate (NDI), para Phenylene diisocyanate (PPDI), tetramethylxylylene diisocyanate (TMXDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI), lysine diisocyanate (LDI), isopropylidenebis (4-cyclohexylisocyanate) ) (IPC), cyclohexyl diisocyanate (CHDI), tolidine diisocyanate (TODI) and the like.

  A catalyst used in this kind of reaction may be used as the crosslinking accelerator. Examples of the crosslinking accelerator include tertiary amines such as 1,4-diaza-bicyclo [2,2,2] octane, and metal compounds such as organic tin compounds. The total amount of the crosslinking agent added may or may not undergo a crosslinking reaction. That is, an unreacted crosslinking agent may be present. Since this type of cross-linking reaction proceeds over time, the presence of an unreacted cross-linking agent does not indicate that the cross-linking reaction has not proceeded at all, but an unreacted cross-linking agent is detected. However, this does not mean that there is no resin in a crosslinked state. Further, as a method for distinguishing whether a polymer is in a crosslinked state or a non-crosslinked state, it can be distinguished by immersing the coating film in a highly soluble solvent. That is, the polymer in the non-crosslinked state dissolves in the solvent and does not remain in the solute, so the presence or absence of the polymer structure of the solute may be analyzed. Therefore, if the presence of a polymer structure in the solute cannot be confirmed, it can be said that the polymer is in a non-crosslinked state, and can be distinguished from a crosslinked polymer. Here, this can be expressed as a gel fraction.

  The gel fraction means the ratio of gel formation when a resin solute in a solvent loses its independent mobility due to interaction and aggregates and forms a state (gel). The resin preferably has a gel fraction of 30% or more, more preferably 50% or more, still more preferably 70% or more, and particularly preferably 80% or more. When the gel fraction is small, repeated durability is lowered. Therefore, in order to improve the gel fraction, a curable resin that is cured by heat, ultraviolet irradiation (UV), electron beam irradiation (EB) or the like is mixed in the resin. Or the resin itself may be cross-linked.

  Here, as the method for measuring the gel fraction, the membrane is peeled off from the support and the initial mass of the membrane is measured, and then the membrane is sandwiched between 400 mesh wire nets in a solvent in which the resin before crosslinking is soluble. It is possible to measure the mass after drying by soaking in a vacuum for 24 hours and then vacuum drying.

The said gel fraction can be calculated | required by following Numerical formula 1.
<Formula 1>
Gel fraction (%) = [mass after drying (g) / initial mass (g)] × 100
When calculating the gel fraction by this calculation, the calculation is performed excluding the mass of organic low-molecular substance particles other than the resin component in the heat-sensitive layer. At this time, when the mass of the organic low molecular weight substance is not known in advance, the area ratio per unit area, the resin and the organic low molecular weight substance are observed by cross-sectional observation using a transmission electron microscope (TEM), a scanning electron microscope (SEM), or the like. It is only necessary to calculate a gel fraction value by calculating a mass ratio based on each specific gravity, calculating a mass of the organic low molecular weight substance.

  In the measurement, a heat sensitive layer is provided on the support and another layer such as a protective layer is laminated thereon, or another layer is provided between the support and the heat sensitive layer. In some cases, first, the thickness of the heat-sensitive layer and other layers is measured by cross-sectional observation of the transmission electron microscope (TEM), scanning electron microscope (SEM), etc., and the thickness of the other layers is measured. And the surface of the heat-sensitive layer is exposed, the heat-sensitive layer is peeled off, and the gel fraction is measured in the same manner as in the measurement method.

  In the method for measuring the gel fraction, when there is a protective layer made of an ultraviolet curable resin or the like in the upper layer of the thermosensitive layer, the thickness of the protective layer is set to prevent the protective layer from being mixed as much as possible. It is necessary to cut the surface of the heat-sensitive layer slightly to prevent the influence on the gel fraction value.

The filler can be roughly classified into an inorganic filler and an organic filler.
Examples of the inorganic filler include calcium carbonate, magnesium carbonate, silicic anhydride, alumina, iron oxide, calcium oxide, magnesium oxide, chromium oxide, manganese oxide, silica, talc, mica, and the like.
Examples of the organic filler include silicone resin, cellulose resin, epoxy resin, nylon resin, phenol resin, polyurethane resin, urea resin, melamine resin, polyester resin, polycarbonate resin; polystyrene resin, styrene-isoprene copolymer, styrene- Styrenic resin such as vinylbenzene copolymer; Acrylic resin such as vinylidene chloride acrylic, acrylic urethane, ethylene acrylic; Polyethylene resin; Formaldehyde resin such as benzoguanamine formaldehyde, melamine formaldehyde; Polymethyl methacrylate resin, polyvinyl chloride resin, etc. Is mentioned.
These may be used individually by 1 type and may use 2 or more types together. In the case of a plurality, there are no particular limitations on how the inorganic filler and organic filler are combined. Examples of the shape include a spherical shape, a granular shape, a plate shape, and a needle shape.
The content of the filler is usually preferably 5 to 50% by volume in terms of volume fraction.

There is no restriction | limiting in particular as said lubricant, It can select suitably according to the objective from well-known things, For example, synthetic waxes, such as ester wax, paraffin wax, and polyethylene wax; Vegetable waxes, such as hardened castor oil Animal waxes such as beef tallow oil; higher alcohols such as stearyl alcohol and behenyl alcohol; higher fatty acids such as margaric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid; fatty acid esters of sorbitan, etc. Higher fatty acid esters; amides such as stearic acid amide, oleic acid amide, lauric acid amide, ethylene bis stearic acid amide, methylene bis stearic acid amide, and methylol stearic acid amide;
The content of the lubricant in the heat-sensitive layer is preferably 0.1 to 95%, more preferably 1 to 75% in terms of volume fraction.

The surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant. Can be mentioned.
The plasticizer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include phosphate ester, fatty acid ester, phthalate ester, dibasic acid ester, glycol, polyester plasticizer, and epoxy plasticizer. Agents, etc.

  There is no restriction | limiting in particular as a method of forming the said heat sensitive layer, According to the objective, it can select suitably, For example, (1) The said binder resin, the said electron-donating coloring compound, and the said electron-accepting compound are included. A method in which a heat-sensitive layer coating solution dissolved or dispersed in a solvent is applied onto a support, and the solvent is evaporated to form a sheet or the like, or at the same time or thereafter, (2) only the binder resin is dissolved A heat-sensitive layer coating solution in which the electron-donating color-forming compound and the electron-accepting compound are dispersed in the solvent is applied onto a support, and the solvent is evaporated to form a sheet or the like, or cross-links thereafter. Method (3) Without using a solvent, the binder resin, the electron-donating color compound, and the electron-accepting compound are heated and melted and mixed together, and the molten mixture is formed into a sheet or the like. cold How to crosslinked after, and the like. In these, it is also possible to form a sheet-like reversible thermosensitive recording medium without using the support.

  The solvent used in the above (1) or (2) differs depending on the kind of the binder resin, the electron donating color compound, and the electron accepting compound and cannot be unconditionally defined. , Methyl ethyl ketone, methyl isobutyl ketone, chloroform, carbon tetrachloride, ethanol, toluene, benzene, and the like. The electron-accepting compound is dispersed in the form of particles in the heat-sensitive layer.

Various pigments, antifoaming agents, pigments, dispersants, slip agents, preservatives, cross-linking agents, plasticizers, and the like are added to the heat-sensitive layer coating solution for the purpose of expressing high performance as a coating material. Also good.
There is no restriction | limiting in particular as the coating method of the said heat sensitive layer, According to the objective, it can select suitably, Conveys the support body cut | judged by roll shape continuously or in sheet form, and on this support body For example, blade coating, wire bar coating, spray coating, air knife coating, bead coating, curtain coating, gravure coating, kiss coating, reverse roll coating, dip coating, die coating, etc. Apply by the method.
There is no restriction | limiting in particular as drying conditions of the said thermosensitive layer coating liquid, According to the objective, it can select suitably, For example, it is about 10 minutes-1 hour at the temperature of room temperature-140 degreeC.

The resin in the heat-sensitive layer can be cured by heating, ultraviolet irradiation, electron beam irradiation, or the like.
The ultraviolet irradiation is not particularly limited and can be performed using a known ultraviolet irradiation apparatus, and examples of the apparatus include a light source, a lamp, a power source, a cooling device, a conveyance device, and the like.
Examples of the light source include a mercury lamp, a metal halide lamp, a gallium lamp, a mercury xenon lamp, and a flash lamp. The wavelength of the light source can be appropriately selected according to the ultraviolet absorption wavelength of the photopolymerization initiator and the photopolymerization accelerator added to the reversible thermosensitive recording medium composition.
The conditions for the ultraviolet irradiation are not particularly limited and may be appropriately selected depending on the purpose. For example, the lamp output, the conveyance speed, etc. may be determined according to the irradiation energy necessary for crosslinking the resin. .

The electron beam irradiation can be performed using a known electron beam irradiation apparatus, and the electron beam irradiation apparatus can be roughly classified into two types, a scanning type (scan beam) and a non-scanning type (area beam). Conditions can be selected according to the irradiation area, irradiation dose, and the like. Further, the electron beam irradiation conditions can be determined from the following Equation 2 in consideration of the electron flow, the irradiation width, and the conveyance speed in accordance with the dose necessary for crosslinking the resin.
<Formula 2>
D = (△ E / △ R) ・ η ・ I / (W ・ V)
However, in the said Numerical formula 2, D represents a required dose (Mrad). ΔE / ΔR represents average energy loss. η represents efficiency. I represents the electron current (mA). W represents the irradiation width (cm). V represents a conveyance speed (cm / s).
Industrially, it is preferable to simplify Equation 2 and use Equation 3 below.
<Formula 3>
D ・ V = K ・ I / W
Here, the device rating is represented by Mrad · m / min, and the electron current rating is selected to be about 20 to 500 mA.

There is no restriction | limiting in particular in the thickness of the said thermosensitive layer, According to the objective, it can select suitably, For example, 1-20 micrometers is preferable and 3-15 micrometers is more preferable.
If the thickness of the heat-sensitive layer is too thin, the color density will be low and the image contrast may be low. However, the target color density may not be obtained.

<Polymer-containing layer having ultraviolet absorbing structure>
In the reversible thermosensitive recording medium, since the background discoloration due to light irradiation is reduced by the light cut in the ultraviolet wavelength region, it has been known that adding an ultraviolet absorber is effective. Preferably, a polymer-containing layer having an ultraviolet absorbing structure is formed on the heat-sensitive layer to prevent background discoloration due to light irradiation.
In this case, the polymer-containing layer having the ultraviolet absorbing structure is not particularly limited as long as it is a layer provided on the heat-sensitive layer, and corresponds to an intermediate layer or a protective layer described later.

  The polymer having the ultraviolet absorbing structure means a polymer having an ultraviolet absorbing group in the molecule. Examples of the ultraviolet absorbing structure include a salicylate structure, a cyanoacrylate structure, a benzotriazole structure, a benzophenone structure, etc. Among them, a bezotriazole structure and a benzophenone structure are particularly preferable.

  There is no restriction | limiting in particular as a polymer which has the said ultraviolet absorption structure, According to the objective, it can select suitably, For example, 2- (2'-hydroxy-5'-methacryloxyethylphenyl) -2H-benzotriazole and Copolymer consisting of 2-hydroxyethyl methacrylate and styrene, copolymer consisting of 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2-hydroxypropyl methacrylate and methyl methacrylate, 2 -(2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2-hydroxyethyl methacrylate, methyl methacrylate and t-butyl methacrylate, 2 , 2,4,4-tetrahydroxybenzophenone and methacrylic acid-2-hydroxypropi A copolymer of styrene and methyl methacrylate and propyl methacrylate, and the like.

  The polymer having an ultraviolet absorbing structure is preferably in a crosslinked state in the layer to be added. Accordingly, the polymer having an ultraviolet absorbing structure is particularly preferably a polymer having a group that undergoes a crosslinking reaction with a curing agent such as a hydroxyl group, an amino group, or a carboxyl group. Among these, a polymer having a hydroxyl group is preferable, and a polymer having 10 or more hydroxyl groups is particularly preferable because sufficient coating strength can be obtained.

  As said hardening | curing agent, what crosslinks with the polymer which has the said ultraviolet absorption structure is used widely, and an isocyanate type hardening | curing agent is preferable. The isocyanate curing agent is a polyisocyanate compound having a plurality of isocyanate groups. For example, hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), or these Examples thereof include adduct type, burette type, isocyanurate type, and blocked isocyanates based on trimethylolpropane. Among these, hexamethylene diisocyanate is preferable, and adduct type, burette type, and isocyanurate type of the hexamethylene diisocyanate are particularly preferable.

  The addition amount of the curing agent is not particularly limited as long as it is a level satisfying the durability of the reversible thermosensitive recording medium, and can be appropriately selected according to the purpose. The number of active groups in the agent is preferably from 0.3 to 2.0, more preferably from 0.8 to 1.5, in terms of molar ratio. When the molar ratio is 0.3 or more, high heat strength is obtained and durability is improved. On the other hand, when it is 2.0 or less, color development and decoloring characteristics are enhanced, which is preferable.

  The reversible thermosensitive recording medium preferably contains an ultraviolet absorber from the viewpoint of preventing background discoloration. There is no restriction | limiting in particular as a layer which adds this ultraviolet absorber, According to the objective, it can select suitably, For example, the polymer containing layer which has the said ultraviolet absorption structure, a heat sensitive layer, a protective layer, an intermediate | middle layer etc. are mentioned. It is done.

The ultraviolet absorber is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include salicylic acid compounds, benzophenone compounds, and benzotriazole compounds. Specifically, phenyl salicylates Rate, monoglycol salicylate, pt-butylphenyl salicylate, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2 (2'-hydroxy-5'-methylphenyl) Benzotriazole, 2 (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole, 2 (2′-hydroxy-3′-t-butyl-5′-methylphenyl) benzotriazole, resorcinol Monobenzoate, 2′-ethylhexyl-2-cyano-3-phenylcinnamate, And the like.
Although the addition amount of the said ultraviolet absorber changes according to the layer to add and cannot be prescribed | regulated unconditionally, 0.5-10 mass parts is preferable with respect to 100 mass parts of resin components in the layer to add.

<Support>
The support is not particularly limited in its shape, structure, size and the like, and can be appropriately selected according to the purpose. Examples of the shape include a flat plate shape, May be a single layer structure or a laminated structure, and the size can be appropriately selected according to the size of the reversible thermosensitive recording medium.

Examples of the material for the support include inorganic materials and organic materials. Examples of the inorganic material include glass, quartz, silicon, silicon oxide, aluminum oxide, SiO ₂ and metal. Examples of the organic material include paper, cellulose derivatives such as cellulose triacetate, synthetic paper, polyethylene terephthalate, polycarbonate, polystyrene, polymethyl methacrylate, and the like. These may be used individually by 1 type and may use 2 or more types together.
Among these, in order to obtain a sheet having high image clarity, polyethylene terephthalate and PET-G film having a haze of the support alone (haze defined by JIS K7105, haze) of 10% or less are particularly preferable.

The support is preferably surface-modified by corona discharge treatment, oxidation reaction treatment (chromic acid, etc.), etching treatment, easy adhesion treatment, antistatic treatment, etc. for the purpose of improving the adhesion of the coating layer. Moreover, it is preferable to add a white pigment such as titanium oxide to the support to make it white.
There is no restriction | limiting in particular as thickness of the said support body, According to the objective, it can select suitably, 10-2,000 micrometers is preferable and 20-1,000 micrometers is more preferable.

  The support may have a magnetic heat sensitive layer on at least one of the same surface and the opposite surface as the heat sensitive layer. In addition, the reversible thermosensitive recording medium of the present invention can be attached to another medium via an adhesive layer or the like.

<Under layer>
The under layer effectively uses the applied heat to increase the sensitivity, or for the purpose of improving the adhesion between the support and the heat sensitive layer or preventing the heat sensitive layer material from penetrating into the support. It is provided between the supports, contains at least hollow particles, and contains a binder resin and, if necessary, other components.

Examples of the hollow particles include single hollow particles in which one hollow portion is present in the particles, and multi-hollow particles in which many hollow portions are present in the particles. These may be used individually by 1 type and may use 2 or more types together.
There is no restriction | limiting in particular as a material of the said hollow particle, Although it can select suitably according to the objective, For example, a thermoplastic resin etc. are mentioned suitably. The void particles may be appropriately manufactured or may be commercially available products. Examples of the commercially available products include Microsphere R-300 (manufactured by Matsumoto Yushi Co., Ltd.), Ropaque HP1055, Ropaque HP433J (all manufactured by Nippon Zeon Co., Ltd.), SX866 (manufactured by JSR Corporation), and the like.
There is no restriction | limiting in particular in the addition amount in the said under layer of the said hollow particle, According to the objective, it can select suitably, For example, 10-80 mass% is preferable.

As the binder resin, the same resin as the heat-sensitive layer or the polymer-containing layer having the ultraviolet absorption structure can be used.
The under layer may contain at least one of inorganic fillers such as calcium carbonate, magnesium carbonate, titanium oxide, silicon oxide, aluminum hydroxide, kaolin, and talc, and various organic fillers.
In addition, the under layer may further contain a lubricant, a surfactant, a dispersant, and the like.
There is no restriction | limiting in particular in the thickness of the said under, and it can select suitably according to the objective, 0.1-20 micrometers is preferable and 0.5-5 micrometers is more preferable.

<Protective layer>
The protective layer contains a binder resin, a release agent, and an ultraviolet absorber, and further contains other components as necessary.
As the binder resin, the same resin as the heat-sensitive layer or the polymer-containing layer having the ultraviolet absorption structure can be used. A thermosetting resin and an ultraviolet curable resin are more preferable, and an ultraviolet curable resin is particularly preferable.

Examples of the release agent include silicone having a polymerizable group, a polymer grafted with silicone, wax, zinc stearate, silicone oil, and the like.
The addition amount of the release agent is preferably 0.01 to 50% by mass, and more preferably 0.1 to 40% by mass with respect to the total mass of the resin component of the protective layer. Even if the addition amount is small, the effect is exhibited, but if it is less than 0.01% by mass, the effect of addition cannot be obtained, and if it exceeds 50% by mass, there may be a problem in adhesion to the lower layer.

As said ultraviolet absorber, the ultraviolet absorber similar to the polymer content layer which has the said ultraviolet absorption structure can be used, Among these, an organic ultraviolet absorber is especially preferable. The addition amount of the ultraviolet absorber is preferably 0.5 to 10% by mass relative to the total mass of the resin component of the protective layer.
As said other component, you may contain conventionally well-known surfactant, a leveling agent, an antistatic agent, etc. as an additive.
As the solvent used in the coating liquid for the protective layer, the dispersion device for the coating liquid, the coating method for the protective layer, the drying method, the curing method, and the like, known methods used in the thermosensitive layer can be used.

  The thickness of the protective layer is preferably from 0.1 to 20 μm, more preferably from 0.5 to 10 μm, still more preferably from 1.5 to 6 μm. When the thickness is less than 0.1 μm, the protective layer is destroyed when the recorded image is repeatedly erased and printed, and sufficient durability cannot be obtained. The function as a reversible thermosensitive recording medium may be lost, and if it exceeds 20 μm, only a blurred image with poor dot reproducibility (fineness of printed image) can be obtained, and there is a problem of thermal conductivity. Therefore, the energy used for printing and erasing increases, and the burden on the apparatus may increase.

<Intermediate layer>
The intermediate layer is used for the purpose of improving adhesion between the heat-sensitive layer and the protective layer, preventing alteration of the heat-sensitive layer by applying the protective layer, and preventing the additives in the protective layer from being transferred to the heat-sensitive layer. It is preferable to provide an intermediate layer, which can improve the storage stability of the color image.

The intermediate layer contains a binder resin and an ultraviolet absorber, and further contains other components as necessary.
As the resin, the resin used in the heat-sensitive layer can be used, and among these, by adding a curable resin, the heat resistance of the reversible heat-sensitive recording medium is further improved, and better repeated durability. Is obtained.

As the UV absorber, the same UV absorber as that of the polymer-containing layer having the UV absorbing structure can be used. Cinnamic acid-based ultraviolet absorbers can be mentioned, and among these, benzotriazole-based is preferable.
The content of the ultraviolet absorber is preferably in the range of 0.5 to 80 parts by mass with respect to 100 parts by mass of the resin component of the intermediate layer.

  The intermediate layer may contain a UV-absorbing or shielding inorganic compound, conventionally known surfactants, leveling agents, antistatic agents and the like as additives.

The solvent used for the intermediate layer coating solution, the dispersion device of the coating solution, the intermediate layer coating method, the intermediate layer drying method, the curing method, etc., use known methods used in the heat-sensitive layer and the protective layer. be able to.
There is no restriction | limiting in particular in the thickness of the said intermediate | middle layer, According to the objective, it can select suitably, 0.1-20 micrometers is preferable and 0.5-5 micrometers is more preferable.

The reversible thermosensitive recording medium of the present invention is not particularly limited, and can be processed into a shape according to its use. For example, it is processed into a card shape, a sheet shape, a label shape, a roll shape, or the like.
As for the one processed into the card shape, application to a prepaid card, a point card, or even a credit card can be mentioned, and a sheet-like one processed into a general document size such as A4 size uses a printing / erasing device. As a result, not only for trial printing but also for a sheet size larger than the card size, the printing range becomes wider, so it can be used widely for temporary output such as general documents, process management instructions, circulation documents and meeting materials. it can.
Furthermore, what was processed into roll shape can be used for a display board, a bulletin board, or an electronic blackboard by incorporating in the apparatus which has a printing / erasing part. Such a display device can be preferably used in a clean room or the like because it does not generate dust or dust.

The reversible thermosensitive recording medium of the present invention may be used in combination with an irreversible thermosensitive layer. In this case, the color tone of each heat sensitive layer may be the same or different. Further, printing (printable part) such as offset printing and gravure printing on a part or the whole of the same surface as the heat-sensitive layer of the reversible thermosensitive recording medium of the present invention, or a part of the opposite surface, or an ink jet printer, a thermal transfer printer, You may provide the coloring layer which can form irreversible information, such as arbitrary patterns, with a sublimation printer. Further, an OP varnish layer mainly composed of a curable resin may be provided on a part or the entire surface of the colored layer. Examples of the arbitrary pattern include characters, patterns, patterns, photographs, information detected by infrared rays, and the like. It is also possible to add a dye or pigment to any one of the simply configured layers for coloring.
Furthermore, the reversible thermosensitive recording medium of the present invention can be provided with a hologram for security. In addition, a design such as a person image, a company emblem, a symbol mark, or the like can be provided by providing irregularities in a relief shape or an intaglio shape for designability.

Formation and deletion of an image on the reversible thermosensitive recording medium can be performed using a known image processing apparatus, and is preferably performed using the image processing apparatus of the present invention described later.
As the image processing apparatus, for example, an apparatus including an image forming unit for forming an image on the reversible thermosensitive recording medium and an image erasing unit for erasing the image is preferably exemplified. Among these, it is preferable to include an image forming and erasing unit that combines the image forming unit and the image erasing unit in that the processing time is short. Specifically, an image processing apparatus or an image forming unit that can process an image by changing the energy applied to the thermal head using a thermal head, or the image forming unit is a thermal head, and the image erasing unit is a thermal head or ceramic. Contact pressing type means for adhering heating elements such as heaters (heat-generating elements screen-printed on an alumina substrate), hot stamps, heat rollers, heat blocks, etc., or non-contact type means using hot air or infrared rays And an image processing apparatus selected from one of them.

(Reversible thermosensitive recording material)
The reversible thermosensitive recording member of the present invention has an information storage unit and a reversible display unit, the reversible display unit includes the reversible thermosensitive recording medium of the present invention, and other members as necessary. It has.

  By providing (integrating) the heat-sensitive layer capable of reversible display and the information storage unit on the same card, and displaying a part of the information stored in the information storage unit on the heat-sensitive layer, the card holder or the like is special. Even if there is no special device, it is possible to confirm information simply by looking at the card, which is very convenient. Further, when the contents of the information storage unit are rewritten, the reversible thermosensitive recording medium can be repeatedly used by rewriting the display of the reversible thermosensitive recording unit.

The members having the information storage unit and the reversible display unit can be roughly classified into the following two members.
(1) A member having an information recording part is used as a support for a reversible thermosensitive recording medium, and a thermosensitive layer is directly formed.
(2) A member having an information recording unit and having a support surface of a reversible thermosensitive recording medium separately formed and having a thermosensitive layer on the support.
In these cases (1) and (2), it is necessary to set the functions of the information storage unit and the reversible display unit so that the functions of the information storage unit and the reversible display unit can be exhibited. It can be provided on the surface of the thermal recording medium opposite to the surface on which the heat-sensitive layer is provided, between the support and the heat-sensitive layer, or on a part of the heat-sensitive layer.

  Although there is no restriction | limiting in particular as said information storage part, For example, a magnetic thermosensitive layer, a magnetic stripe, IC memory, an optical memory, RF-ID tag, a hologram etc. are used preferably. In particular, in a sheet medium having a size larger than the card size, an IC memory and an RF-ID tag are preferably used. The RF-ID tag includes an IC chip and an antenna connected to the IC chip.

As the magnetic heat-sensitive layer, commonly used iron oxide, barium ferrite, etc. and vinyl chloride-based, urethane-based resin, nylon-based resin, etc. are used, and are formed on a support, or methods such as vapor deposition, sputtering, etc. Is formed without using a resin. The magnetic heat-sensitive layer may be provided on the surface of the support opposite to the heat-sensitive layer, or may be provided between the support and the heat-sensitive layer and on a part of the heat-sensitive layer. Further, a reversible thermosensitive material used for display may be used in the storage unit by a barcode, a two-dimensional code, or the like. Among these, magnetic recording and IC are more preferable.
The hologram is preferably rewritable, and examples thereof include a rewritable hologram in which interference light is written on a polymer azobenzene liquid crystal film.

In general, the member having the information recording unit includes a card, a disk, a disk cartridge, or a tape cassette. Specifically, a thick card such as an IC card or an optical card, a flexible disk, a disk cartridge containing a rewritable disk such as a magneto-optical recording disk (MD) or DVD-RAM, or a disk such as a CD-RW. Examples thereof include a disc that does not use a cartridge, a write-once disc such as a CD-R, an optical information recording medium (CD-RW) that uses a phase-change storage material, and a video tape cassette.
Moreover, as a member having both the reversible display unit and the information storage unit, for example, in the case of a card, the card holder or the like is displayed by displaying a part of the information stored in the information storage unit on the heat sensitive layer. Since the information can be confirmed only by looking at the card without a special device, the convenience of the card is greatly improved as compared with a card to which the reversible thermosensitive recording medium is not applied. The information storage unit is not particularly limited as long as it can store necessary information, and can be appropriately selected according to the purpose. For example, magnetic recording, contact IC, non-contact IC, or optical memory is useful. It is.
The magnetic heat-sensitive layer is formed on a support by using a metal compound such as iron oxide, barium ferrite or the like and a resin such as vinyl chloride, urethane or nylon, or a resin. It is formed by a method such as vapor deposition or sputtering using the above metal compound without using it. Further, the thermosensitive layer in the reversible thermosensitive recording medium used for display can be used as a storage unit in a manner such as a bar code or a two-dimensional code.

  More specifically, it can be particularly preferably used in the following reversible thermosensitive recording label, reversible thermosensitive recording member, image processing apparatus, image processing method, and the like of the present invention. In the present invention, the surface of the reversible thermosensitive recording medium means the surface of the thermosensitive layer side, and is not limited to the protective layer, but contacts the thermal head when erasing printing such as the surface of the printing layer or the surface of the OP layer. Means all or part of the face.

The reversible thermosensitive recording member of the present invention includes the reversible display unit and the information storage unit, and a suitable example of the information storage unit is an RF-ID tag. FIG. 2 shows a schematic diagram of the RF-ID tag 85. The RF-ID tag 85 includes an IC chip 81 and an antenna 82 connected to the IC chip. The IC chip 81 is divided into a storage unit, a power supply adjustment unit, a transmission unit, and a reception unit, and each performs communication by sharing the function. In the communication, the RF-ID tag and the reader / writer antenna communicate with each other by radio waves to exchange data. Specifically, an RF-ID antenna receives a radio wave from a reader / writer, and an electromotive force is generated by electromagnetic induction or the like by a resonance action. This activates the IC chip in the RF-ID tag, converts the information in the chip into a signal, and then transmits a signal from the RF-ID tag. This information is received by the antenna on the reader / writer side and recognized by the data processing device, and data processing is performed on the software side.
The RF-ID tag is processed into a label or a card, and the RF-ID tag 85 can be attached to the reversible thermosensitive recording medium 90 of the present invention as shown in FIG. The RF-ID tag 85 can be attached to the heat-sensitive layer surface or the back layer surface, but is preferably attached to the back layer surface. A known adhesive or pressure-sensitive adhesive can be used to bond the RF-ID tag and the reversible thermosensitive recording medium.

4A and 4B show an example in which a reversible thermosensitive recording medium is applied to an industrial rewritable sheet (reversible thermosensitive recording member) 90. FIG. As shown in FIG. 4A, a rewritable display portion 91 is provided on the heat sensitive layer side (front surface), and an RF-ID tag is provided on the back surface (back layer) as shown in FIG. 4B. The RF-ID tag 85 may be attached as shown in FIG. 3, but it is preferable to have the RF-ID tag in terms of convenience. In FIG. 4A, 92 indicates barcode printing.
FIG. 5 shows an example of how to use an industrial rewritable sheet in which the reversible thermosensitive recording medium (rewritable sheet) of the present invention is combined with an RF-ID tag. First, information such as an article name and quantity is recorded on a sheet and an RF-ID tag with respect to delivered raw materials, and attached to a returnable box or the like for inspection. In the next process, a processing instruction is given to the delivered raw material, information is recorded in the rewritable sheet and the RF-ID tag, and a processing instruction document is obtained, and the process proceeds to the processing process. Next, the processed product is attached with a rewritable sheet on which ordering information is recorded as an ordering instruction and an RF-ID tag. After the product is shipped, the rewritable sheet is collected, the shipping information is read, and used again as an invoice.

(Reversible thermosensitive recording label)
The reversible thermosensitive recording label of the present invention is a surface opposite to the image forming surface of the reversible thermosensitive recording medium of the present invention (when the thermosensitive layer is provided on a support, the heat-sensitive layer of the support). The surface on the opposite side of the surface on which is formed) has at least one of an adhesive layer and a pressure-sensitive adhesive layer, and further has other layers appropriately selected as necessary. In the case of a reversible thermosensitive recording medium in which a heat-fusible material is used as the support, an adhesive layer or a pressure-sensitive adhesive layer is not necessarily required on the surface opposite to the surface on which the heat-sensitive layer is formed. Absent.

The shape, structure, size and the like of the adhesive layer to the pressure-sensitive adhesive layer are not particularly limited and may be appropriately selected depending on the purpose. For example, the shape may be a sheet shape, a film shape, or the like. The structure may be a single-layer structure or a laminated structure, and the size may be larger or smaller than the heat-sensitive layer.
The material of the adhesive layer to the pressure-sensitive adhesive layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, urea resin, melamine resin, phenol resin, epoxy resin, vinyl acetate resin, acetic acid Vinyl-acrylic copolymer, ethylene-vinyl acetate copolymer, acrylic resin, polyvinyl ether resin, vinyl chloride-vinyl acetate copolymer, polystyrene resin, polyester resin, polyurethane resin, polyamide resin Chlorinated polyolefin resin, polyvinyl butyral resin, acrylic ester copolymer, methacrylic ester copolymer, natural rubber, cyanoacrylate resin, silicone resin, and the like. These may be used individually by 1 type, may use 2 or more types together, may be a hot melt type, may use a release paper, and may be a non-release paper type.

  The reversible thermosensitive recording label is usually used by being attached to a base sheet such as a card. The reversible thermosensitive recording label to be affixed to the base sheet may be the entire surface of the base sheet, a part thereof, or may be provided on one side or both sides of the base sheet. It is selected appropriately.

The substrate sheet is not particularly limited in its shape, structure, size and the like, and can be appropriately selected according to the purpose. Examples of the shape include a flat plate shape, and the like. The structure may be a single layer structure or a laminated structure, and the size may be appropriately selected according to the size of the reversible thermosensitive recording medium, for example, chlorine A sheet made of a material such as a containing polymer, a polyester resin, or a biodegradable plastic resin, or a laminate thereof is used.
The chlorine-containing polymer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer Vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride-acrylate copolymer, polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer, and the like.
Examples of the polyester resin include polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), or a condensed ester resin of an acid component such as terephthalic acid and isophthalic acid and an alcohol component such as ethylene glycol and cyclohexanedimethanol. (For example, PETG: a trademark of Eastman Chemical Co.).
Examples of the biodegradable plastic resin include a polylactic acid resin, a natural polymer resin composed of starch and modified polyvinyl alcohol, a microorganism-produced resin composed of β-hydroxybutyric acid and β-hydroxyvaleric acid, and the like. Can be mentioned.
Furthermore, synthetic resin sheets or synthetic papers such as polyacetate resin, polystyrene (PS) resin, epoxy resin, polyvinyl chloride (PVC) resin, polycarbonate (PC) resin, polyamide resin, acrylic resin, silicone resin, etc. These materials may be appropriately combined, or a laminate of these materials may be used.

  As the laminate, for example, a core sheet in which two white polyvinyl chloride resin sheets having a thickness of 250 μm are laminated, and a transparent polyvinyl chloride resin sheet having a thickness of 100 μm laminated on the front and back surfaces of the core sheet as an oversheet, Moreover, for example, a core sheet in which two white PETG sheets having a thickness of 250 μm are laminated, and a transparent PETG having a thickness of 100 μm laminated as an oversheet on the front and back surfaces of the core sheet, and the like can be mentioned.

As a method for attaching the base sheet and the reversible thermosensitive recording label, for example, as shown in FIG. 6, two sheets in which the reversible thermosensitive recording label 3 and the base sheet 4 are overlapped so as to face each other. After being sandwiched by the mirror plate 2, the heat plate 1 is pressed while applying heat.
Further, as shown in FIG. 7, it can be performed in the same manner as in FIG. 6 except that the base sheet 4 formed by superposing the core sheet 6 and the oversheet 7 is used.
Thermocompression bonding, known means, for example using a heat press machine hot plate 1 is provided, usually, 5~70kgf / cm ^2, preferably to a pressure of 10~50kgf / cm ^2, 80~170 ℃, preferably Is carried out in the range of 90 to 150 ° C.
For example, when a laminate such as a transparent polyvinyl chloride sheet / white polyvinyl chloride sheet / white polyvinyl chloride sheet / transparent polyvinyl chloride sheet is used as the base sheet, the heating temperature during the thermocompression bonding is About 130 to 150 ° C. is preferable. The heating temperature when a laminate such as transparent PETG / white PETG / white PETG / transparent PETG is used is preferably about 100 to 130 ° C.

As another method of attaching the reversible thermosensitive recording label and the base sheet, heat bonding can be performed after heat bonding in advance. The heat bonding is performed by pressing a rubber roll or the like, and then heat bonding is completed to complete the heat bonding.
The thermal bonding conditions are not particularly limited, and optimum conditions are determined depending on the substrate sheet to be used. Usually, the thermal bonding can be performed at a temperature of 90 to 130 ° C. for 1 hour or less and 1 to 50 minutes. .

  In the present invention, for example, when a reversible thermosensitive recording label having a protective layer whose surface is roughened by a filler or the like is thermocompression-bonded on a substrate sheet such as a card, the filler on the surface of the protective layer is in the protective layer by thermocompression bonding. Or the surface gloss is increased by being pushed into the lower layer, the effect of the filler is lost and the durability is repeatedly reduced, or the printing / erasing is repeated if printing / erasing is repeated with the surface gloss further increased. The glossiness of the recording medium decreases and the difference in glossiness from the non-printed / erased portion is recognized as uneven glossiness. However, by providing the protective layer of the reversible thermosensitive recording medium of the present invention, such a problem occurs. Can also be solved. In this case, it is preferable that the reversible thermosensitive recording medium has a surface roughness of 0.15 [mu] m or less because glossiness can be further obtained.

  When the reversible thermosensitive recording label has at least one of the adhesive layer and the pressure-sensitive adhesive layer, the entire surface of a thick substrate such as a card made of vinyl chloride with a magnetic stripe, which is difficult to apply the thermosensitive layer, or the like. A part of information stored in the magnetism can be displayed.

  The reversible thermosensitive recording label includes a thick card such as an IC card or an optical card, a flexible disk, a disk cartridge containing a rewritable disk such as a magneto-optical recording disk (MD) or DVD-RAM, a CD-RW. Such as discs that do not use disc cartridges, write-once discs such as CD-R, optical information recording media (CD-RW) using phase change storage materials, and display labels on video tape cassettes. it can.

FIG. 8 shows an example in which the reversible thermosensitive recording label 10 of the present invention is affixed onto an MD disk cartridge 70. In this case, it is possible to apply to uses such as automatically changing the display contents in accordance with the change of the contents stored in the MD. In the case of a disc that does not use a disc cartridge such as a CD-RW, the reversible thermosensitive recording label of the present invention may be directly attached to the disc.
FIG. 9 shows an example in which the reversible thermosensitive recording label 10 of the present invention is affixed on the CD-RW 71. In this case, the reversible thermosensitive recording label can be pasted on a write-once disc such as a CD-R instead of a CD-RW, and a part of the stored information added to the CD-R can be rewritten and displayed. It is.

  FIG. 10 shows an example in which the reversible thermosensitive recording label 10 of the present invention is pasted on an optical information recording medium (CD-RW) using an AgInSbTe phase change type storage material. The basic configuration of this CD-RW is that a first dielectric layer 110, an optical information storage layer 109, a second dielectric layer 108, a reflective heat dissipation layer 107, and an intermediate layer 106 are formed on a base 111 having a guide groove. The hard coat layer 112 is provided on the back surface of the substrate 111 in order. The reversible thermosensitive recording label 10 of the present invention is affixed on the CD-RW intermediate layer 106. The reversible thermosensitive recording label 10 includes an adhesive layer or an adhesive layer 105, a back layer 104, a support 103, a thermosensitive layer 102, and a protective layer 101 in this order. The dielectric layer is not necessarily provided on both sides of the optical information storage layer, but the first dielectric layer 110 may be provided when the substrate is made of a material having low heat resistance such as polycarbonate resin. desirable.

  FIG. 11 shows an example in which the reversible thermosensitive recording label 10 of the present invention is stuck on a video cassette 72. In this case, the display content can be automatically changed according to the change in the content stored in the video tape cassette.

  As a method of providing the reversible thermosensitive recording function on any of a card, a disk, a disk cartridge, and a tape cassette, in addition to the method of attaching the reversible thermosensitive recording label, the thermosensitive layer is directly formed on them. Examples thereof include a coating method, a method in which the heat-sensitive layer is formed on another support in advance, and the heat-sensitive layer is transferred onto the card, the disk, the disk cartridge, and the tape cassette. In the case of the method for transferring the heat-sensitive layer, the adhesive layer such as a hot-melt type or the pressure-sensitive adhesive layer may be provided on the heat-sensitive layer. When the reversible thermosensitive recording label is affixed on a rigid object such as the card, the disc, the disc cartridge, and the tape cassette, or when the thermosensitive layer is provided, the contact with the thermal head is improved. In order to form an image uniformly, it is preferable that a layer or sheet serving as a cushion is provided between a rigid substrate and a label or the heat-sensitive layer.

In the reversible thermosensitive recording medium of the present invention, for example, as shown in FIG. 12, a reversible thermosensitive layer 13, an intermediate layer 14, and a protective layer 15 are provided on a support 11, and a back layer is provided on the back surface of the support 11. 13, a film in which a reversible thermosensitive layer 13 and a protective layer 15 are provided on a support 11, and a back layer 16 is provided on the back surface of the support 11, as shown in FIG. Embodiments can be taken.
The film (reversible thermosensitive recording medium) of these embodiments can be suitably used for various sheet-like industrial rewritable sheets provided with the RF-ID tag 85 shown in FIG. For example, as shown to FIG. 14A, it can use as a form processed into the reversible thermosensitive recording card 21 which has the print display part 23. FIG. As shown in FIG. 14B, a magnetic recording part is formed on the back side of the card, and a back layer 24 is formed on the magnetic recording part.

  In addition, the reversible thermosensitive recording member (card) shown in FIG. 15A is formed on a support by processing a film provided with a reversible thermosensitive layer and a protective layer into a card shape, thereby forming a recess 25 for accommodating an IC chip. At the same time, it is processed into a card shape. In FIG. 15A, the rewrite recording portion 26 is labeled on a card-like reversible thermosensitive recording medium, and an IC chip embedding recess 25 is formed at a predetermined location on the back side of the card. As shown in FIG. 15B, the wafer 231 is assembled and fixed in the recess 25. In the wafer 231, an integrated circuit 233 is provided on a wafer substrate 232, and a plurality of contact terminals 234 that are electrically connected to the integrated circuit 233 are provided on the wafer substrate 232. The contact terminal 234 is exposed on the back side of the wafer substrate 232 and is configured such that a dedicated printer (reader / writer) can electrically contact the contact terminal 234 to read or rewrite predetermined information. Yes.

Next, the function of the reversible thermosensitive recording card will be described with reference to FIG. FIG. 16A is a schematic configuration block diagram showing the integrated circuit 233. FIG. 16B is a configuration block diagram illustrating an example of data stored in the RAM. The integrated circuit 233 is composed of, for example, an LSI, in which a CPU 235 capable of executing a control operation in a predetermined procedure, a ROM 236 for storing operation program data of the CPU 235, writing of necessary data, and the like. A RAM 237 capable of reading is included. Further, the integrated circuit 233 receives an input signal, gives input data to the CPU 235, receives an output signal from the CPU 235, and outputs it to the outside. Although not shown, a power-on reset circuit, A clock generating circuit, a pulse frequency dividing circuit (interrupt pulse generating circuit), and an address decoding circuit.
The CPU 235 can execute the operation of the interrupt control routine according to the interrupt pulse periodically given from the pulse frequency dividing circuit. The address decoding circuit decodes address data from the CPU 235 and provides signals to the ROM 236, the RAM 237, and the input / output interface 238, respectively. A plurality (eight in FIG. 16) of contact terminals 234 are connected to the input / output interface 238, and predetermined data from the dedicated printer (reader / writer) is transmitted from the contact terminals 234 via the input / output interface 238. Input to the CPU 235. The CPU 235 performs each operation in response to the input signal and according to the program data stored in the ROM 236, and outputs predetermined data and signals to the sheet reader / writer via the input / output interface 238.

  As illustrated in FIG. 16B, the RAM 237 includes a plurality of storage areas 239a to 239g. For example, the sheet number is stored in the area 239a. For example, the storage area 239b stores ID data such as the name, affiliation, and telephone number of the sheet manager. For example, the storage area 239c stores information on the remaining margin or handling that can be used by the user. For example, the storage area 239d, the storage area 239e, the storage area 239f, and the storage area 239g store information related to the previous manager, the previous user, and the like.

  There is no particular limitation on at least one of the reversible thermosensitive recording label and the reversible thermosensitive recording member of the present invention, and image processing can be performed by various image processing methods and image processing apparatuses. An image can be formed and erased suitably using an image processing apparatus.

(Image processing method and image processing apparatus)
The image processing apparatus of the present invention includes at least one of an image forming unit and an image erasing unit, and further includes other units selected as necessary, for example, a transport unit, a control unit, and the like.
In the image processing method of the present invention, the reversible thermosensitive recording medium of the present invention is heated to perform at least one of image formation and erasure, and other processes appropriately selected as necessary, for example, a transport process And a control process.

  The image processing method of the present invention can be preferably carried out by the image processing apparatus of the present invention, and at least one of image formation and image erasure by heating the reversible thermosensitive recording medium of the present invention is the image. It can be performed by at least one of a forming unit and an image erasing unit, and the other steps can be performed by the other units.

-Image forming means and image erasing means-
The image forming means is a means for forming an image by heating the reversible thermosensitive recording medium of the present invention. The image erasing means is means for erasing an image by heating the reversible thermosensitive recording medium of the present invention.
There is no restriction | limiting in particular as said image formation means, According to the objective, it can select suitably, For example, a thermal head, a laser, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.
The image erasing means is means for erasing an image by heating the reversible thermosensitive recording medium of the present invention, such as a hot stamp, a ceramic heater, a heat roller, a heat block, hot air, etc., a thermal head, a laser Irradiation apparatus etc. are mentioned. Among these, a ceramic heater is preferable. By using the ceramic heater, the apparatus can be miniaturized, a stable erased state can be obtained, and an image with good contrast can be obtained. There is no restriction | limiting in particular as preset temperature of the said ceramic heater, According to the objective, it can select suitably, For example, 110 degreeC or more is preferable, 112 degreeC or more is more preferable, and 115 degreeC or more is especially preferable.

By using the thermal head, the size can be further reduced, the power consumption can be reduced, and a battery-driven handy type device can also be realized. Also, a single thermal head can be used for recording and erasing the image. In this case, the size can be further reduced. When recording and erasing with one thermal head, once all the previous images are erased, a new image may be recorded again, or the energy is changed for each image and the previous image is erased at one time. An overwrite method for recording images is also possible. In the overwrite method, the time required for recording and erasing the image is reduced, leading to an increase in recording speed.
In the case of using a reversible thermosensitive recording member (card) having the thermosensitive layer and the information storage unit, the apparatus includes means for reading the memory of the information storage unit, rewriting means, and the like.

  The transport means is not particularly limited as long as it has a function of sequentially transporting the reversible thermosensitive recording medium, and can be appropriately selected depending on the purpose. For example, the transport belt, the transport roller, the transport belt and the transport belt Combination with a roller, etc. are mentioned.

  The control means is not particularly limited as long as it has a function of controlling each step, and can control each step, and examples thereof include devices such as a sequencer and a computer.

  One mode for carrying out the image processing method of the present invention by the image processing apparatus of the present invention will be described with reference to FIGS. As shown in FIG. 17, the image processing apparatus 100 includes a heat roller 96, a thermal head 95, and a conveyance roller. In this image processing apparatus, the image recorded on the heat sensitive layer is heated and erased by the heat roller 96. Next, the processed new information is recorded on the heat sensitive layer by the thermal head 95. In FIG. 17, 97 represents a paper feed tray, and 98 represents a rewritable sheet (reversible thermosensitive recording medium).

When the reversible thermosensitive recording medium has an RF-ID tag, an RF-ID reader 99 is further provided as shown in FIGS. In this case, there is also an aspect of a parallel type image processing apparatus as shown in FIG.
As shown in FIGS. 18 and 19, in this image processing apparatus 100, first, information of the RF-ID tag attached to the reversible thermosensitive recording medium is read by the RF-ID reader / writer 99, and new information is read by RF. -After inputting the ID, the image recorded on the heat sensitive layer is erased by heating with the heat roller 96. Further, based on the information read and rewritten by the RF-ID reader / writer, the processed new information is recorded on the heat sensitive layer by the thermal head.
Other than the RF-ID reader / writer, a bar code reader, a magnetic head, or the like may be used. In the case of a barcode reader, after reading the barcode information already recorded on the reversible thermosensitive layer, the barcode and visualization information recorded on the reversible thermosensitive layer are erased by the heat roller, and the information read from the barcode New information processed based on the data is recorded on the reversible thermosensitive layer by the thermal head as barcode and visualization information.

The image processing apparatus shown in FIG. 17 or 18 has a tray on which a reversible thermosensitive recording medium is stacked, and the medium is picked up one by one by a paper feeding method such as a friction pad method. The transported medium is transported by transport rollers and sent to the RF-ID reader / writer, where data is read and written. Further, the reversible thermosensitive recording medium is transported by the transport roller to the heat roller section which is an erasing unit, and the visualization information recorded on the medium is erased. Then, it is conveyed to a thermal head unit and new information is recorded on a reversible thermosensitive recording medium. Thereafter, the reversible thermosensitive recording medium is conveyed by the conveying roller, and the medium is unloaded from the upper paper discharge unit.
Here, the set temperature of the heat roller is preferably set to match the erasing temperature of the reversible thermosensitive recording medium. For example, the heat roller surface temperature is preferably 100 ° C. or higher and 190 ° C. or lower, more preferably 110 ° C. or higher and 180 ° C. or lower, and even more preferably 115 ° C. or higher and 170 ° C. or lower.

Further description will be made with reference to FIGS. 20A and 20B. The image processing apparatus shown in FIG. 20A includes a thermal head 53, a ceramic heater 38, a magnetic head 34, and conveying rollers 31, 40, and 47 as the heat processing means.
As shown in FIG. 20A, in this image processing apparatus, information stored in the magnetic thermosensitive layer of the reversible thermosensitive recording medium is first read by a magnetic head. Next, the image recorded on the reversible thermosensitive layer is erased by heating with a ceramic heater. Further, new processed information is recorded on the reversible thermosensitive layer by the thermal head based on the information read by the magnetic head. Thereafter, the information of the magnetic thermosensitive layer is also rewritten with new information.
In the image processing apparatus shown in FIG. 20A, the reversible thermosensitive recording medium 5 provided with a magnetic thermosensitive layer on the opposite side of the thermosensitive layer is conveyed along a conveyance path indicated by a reciprocating arrow, or along the conveyance path. Then it is transported in the reverse direction. The reversible thermosensitive recording medium 5 is magnetically recorded or erased on the magnetic thermosensitive layer between the magnetic head 34 and the conveying roller 31, and is heat-treated for image erasing between the ceramic heater 38 and the conveying roller 40, and the thermal head 53 and the area conveying. An image is formed between the rollers 47. Then, it is carried out of the apparatus. As described above, the set temperature of the ceramic heater 38 is preferably 110 ° C. or higher, more preferably 112 ° C. or higher, and particularly preferably 115 ° C. or higher. However, the rewriting of the magnetic recording may be performed before or after the image erasure by the ceramic heater. If desired, after passing between the ceramic heater 38 and the transport roller 40 or after passing between the thermal head 53 and the transport roller 47, the transport path is transported in the reverse direction. A second heat treatment by the ceramic heater 38 and a second printing process by the thermal head 53 can be performed.

  In the image processing apparatus of FIG. 20B, the reversible thermosensitive recording medium 5 inserted from the entrance / exit 30 advances along the conveyance path 50 shown by a one-dot broken line, or reverses the inside of the apparatus along the conveyance path 50. Proceed in the direction. The reversible thermosensitive recording medium 5 inserted from the entrance / exit 30 is transported in the recording apparatus by a transport roller 31 and a guide roller 32. When the sensor 33 reaches a predetermined position in the transport path 50, its presence is recognized by the control means 34c via the control means 34c, and magnetic recording or recording is erased or recorded on the magnetic thermosensitive layer between the magnetic head 34 and the platen roller 35. Between the ceramic roller 38 and the platen roller 44, which passes between the conveying rollers 37, passes between the guide roller 39 and the conveying roller 40, and operates by recognizing its presence via the ceramic heater control means 38 c by the sensor 43. The image is heated for image erasing, is conveyed in the conveyance path 50 by conveyance rollers 45, 46 and 47, and is operated by recognizing its presence via the thermal head control means 53c by the sensor 51 at a predetermined position. An image is formed between the head 53 and the platen roller 52, and the conveyance roller 59 and the gas are conveyed from the conveyance path 56a. It is unloaded outside the apparatus through the outlet 61 by Dorora 60. Here, there is no restriction | limiting in particular as preset temperature of the ceramic heater 38, According to the objective, it can select suitably, As mentioned above, 110 degreeC or more is preferable, 112 degreeC or more is more preferable, 115 degreeC or more is preferable. Particularly preferred.

  If desired, reversible thermosensitive recording is performed by a conveyor belt 58 which is guided to the conveyor path 56b by switching the conveyor path switching means 55a and moves in the reverse direction by the operation of a limit switch 57a input by pressing the reversible thermosensitive recording medium 5. After the medium 5 is again heat-treated between the thermal head 53 and the platen roller 52, the medium 5 is conveyed in the forward direction via the conveying path 49b, the limit switch 57b, and the conveying belt 48 which are communicated by switching the conveying path switching means 55b. From 56a, it can be carried out of the apparatus through the outlet 61 by the conveying roller 59 and the guide roller 60. Further, such branched conveyance paths and conveyance switching means can be provided on both sides of the ceramic heater 38. In that case, it is desirable to provide the sensor 43 a between the platen roller 44 and the transport roller 45.

  According to the image processing apparatus and the image processing method of the present invention, since the reversible thermosensitive recording medium of the present invention is used as the reversible thermosensitive recording medium, light resistance is improved, erasure residue due to repeated printing is small, and high An image having a color density can be formed.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
<Preparation of reversible thermosensitive recording medium>
-Preparation of heat sensitive layer-
4 parts by mass of an electron-accepting compound (developer) represented by the following structural formula, 1 part by mass of dialkylurea (manufactured by Nippon Kasei Co., Ltd., Hakurin SB), 40% by mass solution of acrylic polyol resin (manufactured by Mitsubishi Rayon Co., Ltd.) , LR327) 10 parts by mass, phenolic antioxidant containing a sulfur atom having an alkyl group on one side represented by the following structural formula (Ciba Specialty Chemicals, IRGANOX1520L) 0.06 parts by mass, and methyl ethyl ketone 80 parts by mass The composition consisting of parts was pulverized and dispersed using a ball mill so that the average particle size was 1.0 μm.

<Electron-accepting compound (developer)>

<IRGANOX1520L>

1 part by mass of 2-anilino-3-methyl-6dibutylaminofluorane and 3 parts by mass of isocyanate (manufactured by Nippon Polyurethane Co., Ltd., Coronate HL) are added to the resulting dispersion, and the mixture is thoroughly stirred, and the heat-sensitive layer coating solution Was prepared.
The obtained heat-sensitive layer coating solution was applied onto a 125 μm thick white turbid polyester film (Tetron Film U2L98W, manufactured by Teijin DuPont) using a wire bar, dried at 100 ° C. for 2 minutes, and then heated at 60 ° C. for 24 minutes. Heating for a period of time provided a heat-sensitive layer having a thickness of 11 μm.

-Production of intermediate layer-
Acrylic polyol resin 50 mass% solution (Mitsubishi Rayon Co., Ltd., LR327) 3 mass parts, Zinc oxide fine particle 30 mass% dispersion (Sumitomo Cement Co., Ltd., ZS303) 7 mass parts, Isocyanate (Nihon Polyurethane Co., Ltd., Coronate HL) 1.5 parts by mass and 7 parts by mass of methyl ethyl ketone were thoroughly stirred to prepare an intermediate layer coating solution.
The obtained intermediate layer coating solution was applied onto the heat-sensitive layer with a wire bar, dried at 90 ° C. for 1 minute, and then heated at 60 ° C. for 2 hours to provide an intermediate layer having a thickness of 2.0 μm.

-Production of protective layer-
3 parts by mass of pentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA), 3 parts by mass of urethane acrylate oligomer (manufactured by Negami Kogyo Co., Ltd., Art Resin UN-3320HA), acrylic ester of dipentaerythritol caprolactone ( Nippon Kayaku Co., Ltd., KAYARAD DPCA-120) 3 parts by mass, silica (Mizusawa Chemical Co., Ltd., P-526) 1 part by mass, photopolymerization initiator (Nippon Ciba Geigy Co., Ltd., Irgacure 184) 0.5 A composition comprising 11 parts by mass of mass and isopropyl alcohol was thoroughly stirred with a ball mill and dispersed until the average particle size became about 3 μm to prepare a protective layer coating solution.
The obtained protective layer coating solution was coated on the intermediate layer with a wire bar, dried by heating at 90 ° C. for 1 minute, and then crosslinked under an ultraviolet lamp with an irradiation energy of 80 W / cm to form a protective layer having a thickness of 3 μm. Was provided.
Thus, a reversible thermosensitive recording medium of Example 1 was produced.

(Example 2)
<Preparation of reversible thermosensitive recording medium>
A reversible thermosensitive recording medium of Example 2 was produced in the same manner as in Example 1 except that the thermosensitive layer coating solution was prepared as follows in Example 1.
-Preparation of thermosensitive layer coating solution-
4 parts by mass of an electron-accepting compound (developer) represented by the following structural formula, 1 part by mass of dialkylurea (manufactured by Nippon Kasei Co., Ltd., Hakurin SB), 40% by mass solution of acrylic polyol resin (manufactured by Mitsubishi Rayon Co., Ltd.) , LR327) 10 parts by mass, 1.5 parts by mass of a phenolic antioxidant containing a sulfur atom having an alkyl group on one side represented by the following structural formula (IRGANOX565, manufactured by Ciba Specialty Chemicals), and 80 parts by mass of methyl ethyl ketone The composition consisting of parts was pulverized and dispersed using a ball mill so that the average particle size was 1.0 μm.

<Electron-accepting compound (developer)>

<IRGANOX565>

  1 part by mass of 2-anilino-3-methyl-6dibutylaminofluorane and 3 parts by mass of isocyanate (manufactured by Nippon Polyurethane Co., Ltd., Coronate HL) are added to the resulting dispersion, and the mixture is thoroughly stirred to give a heat-sensitive layer coating solution. Was prepared.

(Example 3)
<Preparation of reversible thermosensitive recording medium>
A reversible thermosensitive recording medium of Example 3 was produced in the same manner as in Example 1 except that the intermediate layer was formed as follows in Example 1.
-Production of intermediate layer-
An intermediate layer coating solution was prepared by thoroughly stirring 50 parts by mass of a UV absorbent polymer 40% by mass solution (manufactured by Nippon Shokubai Co., Ltd., UV-A11) and 50 parts by mass of methyl ethyl ketone.
The obtained intermediate layer coating solution was applied onto the heat-sensitive layer with a wire bar, dried at 90 ° C. for 1 minute, and then heated at 60 ° C. for 2 hours to provide an intermediate layer having a thickness of 2.0 μm.

Example 4
<Preparation of reversible thermosensitive recording medium>
In Example 1, the reversible thermosensitive recording medium of Example 4 was produced in the same manner as in Example 1 except that the intermediate layer was formed as follows.
-Production of intermediate layer-
UV absorptive polymer 40 mass% solution (manufactured by Nippon Shokubai Co., Ltd., UV-A11) 50 parts by mass, isocyanate (manufactured by Nippon Polyurethane Co., Ltd., Coronate HL) 7 parts by mass, and methyl ethyl ketone 43 parts by mass were mixed well. A layer coating solution was prepared.
The obtained intermediate layer coating solution was applied onto the heat-sensitive layer with a wire bar, dried at 90 ° C. for 1 minute, and then heated at 60 ° C. for 2 hours to provide an intermediate layer having a thickness of 2.0 μm.

(Example 5)
<Preparation of reversible thermosensitive recording medium>
A reversible thermosensitive recording medium of Example 5 was produced in the same manner as in Example 1 except that the intermediate layer was formed as follows in Example 1.
-Production of intermediate layer-
Ultraviolet-absorbing polymer 40% by mass solution (Nippon Shokubai Co., Ltd., UV-A11) 50 parts by mass, isocyanate (Nippon Polyurethane Co., Ltd., Coronate HL) 7 parts by mass, UV absorber (Everlight Chemical Co., Eversorb 73) 3.5 parts by mass and 43 parts by mass of methyl ethyl ketone were thoroughly stirred to prepare an intermediate layer coating solution.
The obtained intermediate layer coating solution was applied onto the heat-sensitive layer with a wire bar, dried at 90 ° C. for 1 minute, and then heated at 60 ° C. for 2 hours to provide an intermediate layer having a thickness of 2.0 μm.

(Example 6)
<Preparation of reversible thermosensitive recording medium>
In Example 5, the reversible thermosensitive recording medium of Example 6 was produced in the same manner as in Example 5 except that the thermosensitive layer coating solution was prepared as follows.
-Preparation of thermosensitive layer coating solution-
4 parts by mass of an electron-accepting compound (developer) represented by the following structural formula, 1 part by mass of dialkylurea (manufactured by Nippon Kasei Co., Ltd., Hakurin SB), 40% by mass solution of acrylic polyol resin (manufactured by Mitsubishi Rayon Co., Ltd.) , LR327) 10 parts by mass, phenolic antioxidant containing a sulfur atom having an alkyl group on one side represented by the following structural formula (IRGANOX565, manufactured by Ciba Specialty Chemicals) 0.15 parts by mass, and 80 parts by mass of methyl ethyl ketone The composition consisting of parts was pulverized and dispersed using a ball mill so that the average particle size was 1.0 μm.

<Electron-accepting compound (developer)>

<IRGANOX565>

  1 part by mass of 2-anilino-3-methyl-6dibutylaminofluorane and 3 parts by mass of isocyanate (manufactured by Nippon Polyurethane Co., Ltd., Coronate HL) are added to the resulting dispersion, and the heat sensitive layer coating solution is stirred well. Prepared.

(Example 7)
-Production of reversible thermosensitive recording medium-
In Example 6, 0.15 parts by mass of phenolic antioxidant (IRGANOX565, manufactured by Ciba Specialty Chemicals Co., Ltd.) containing a sulfur atom having an alkyl group on one side in the composition of the thermosensitive layer coating solution is 1.2 parts by mass. A reversible thermosensitive recording medium of Example 7 was produced in the same manner as in Example 6 except for changing.

(Example 8)
<Preparation of reversible thermosensitive recording medium>
In Example 7, an under layer coating solution prepared as follows was applied on a 125 μm thick white turbid polyester film (Tetron Film U2L98W, manufactured by Teijin DuPont) using a wire bar, and at 80 ° C. for 2 minutes. It dried and provided the under layer of thickness 20 micrometers.
Next, a thermosensitive layer, an intermediate layer, and a protective layer were formed on the obtained under layer in the same manner as in Example 7 to produce a reversible thermosensitive recording medium of Example 8.

-Preparation of under layer coating solution-
30 parts by mass of a styrene-butadiene copolymer (manufactured by Nippon A & L Co., PA-9159), 12 parts by mass of polyvinyl alcohol (manufactured by Kuraray Co., Ltd., Poval PVA103), hollow particles (manufactured by Matsumoto Yushi Co., Ltd., Microsphere R-300) ) 20 parts by mass and 40 parts by mass of water were added, and the mixture was stirred and dispersed uniformly for about 1 hour to prepare an under layer coating solution.

Example 9
-Production of reversible thermosensitive recording medium-
In Example 1, the reversible thermosensitive recording of Example 9 was performed in the same manner as in Example 1 except that the electron-accepting compound (developer) in the photosensitive layer coating solution was changed to a compound represented by the following structural formula. A medium was made.

(Example 10)
-Production of reversible thermosensitive recording medium-
In Example 1, the reversible thermosensitive recording of Example 10 was performed in the same manner as in Example 1 except that the electron accepting compound (developer) in the photosensitive layer coating solution was changed to a compound represented by the following structural formula. A medium was made.

(Example 11)
-Production of reversible thermosensitive recording medium-
In Example 8, the reversible thermosensitive recording of Example 11 was carried out in the same manner as in Example 8, except that the electron-accepting compound (developer) in the photosensitive layer coating solution was changed to a compound represented by the following structural formula. A medium was made.

(Comparative Example 1)
-Production of reversible thermosensitive recording medium-
Example 1 is the same as Example 1 except that the phenolic antioxidant containing a sulfur atom having an alkyl group on one side (IRGANOX1052L, manufactured by Ciba Specialty Chemicals) is excluded from the composition of the thermosensitive layer coating solution. Thus, a heat-sensitive layer, an intermediate layer, and a protective layer were provided to prepare a reversible heat-sensitive recording medium.

(Comparative Example 2)
-Production of reversible thermosensitive recording medium-
Example 4 is the same as Example 4 except that the phenolic antioxidant containing a sulfur atom having an alkyl group on one side (IRGANOX565, manufactured by Ciba Specialty Chemicals) is excluded from the composition of the thermosensitive layer coating solution. Thus, a heat-sensitive layer, an intermediate layer, and a protective layer were provided to prepare a reversible heat-sensitive recording medium.

(Comparative Example 3)
-Production of reversible thermosensitive recording medium-
In Example 4, a phenolic antioxidant containing a sulfur atom having an alkyl group on one side in the composition of the thermosensitive layer coating solution (IRGANOX1052L, manufactured by Ciba Specialty Chemicals) is represented by the following structural formula. A heat-sensitive layer, an intermediate layer, and a protective layer were provided in the same manner as in Example 4 except that it was changed to (Ciba Specialty Chemicals, IRGANOX 1076), and a reversible heat-sensitive recording medium was produced.

<IRGANOX1076>

(Comparative Example 4)
-Production of reversible thermosensitive recording medium-
In Example 4, a phenolic antioxidant containing a sulfur atom having an alkyl group on one side in the composition of the heat-sensitive layer coating solution (manufactured by Ciba Specialty Chemicals, IRGANOX1052L) is represented by the following structural formula. A heat-sensitive layer, an intermediate layer, and a protective layer were provided in the same manner as in Example 4 except that AO-503 (Asahi Denka Kogyo Co., Ltd.) was used to produce a reversible thermosensitive recording medium.

<AO-503>

(Comparative Example 5)
-Production of reversible thermosensitive recording medium-
In Example 4, a phenolic antioxidant containing a sulfur atom having an alkyl group on one side in the composition of the thermosensitive layer coating solution (IRGANOX1052L, manufactured by Ciba Specialty Chemicals) is represented by the following structural formula. A reversible thermosensitive recording medium was prepared in the same manner as in Example 4 except that the thermosensitive layer, the intermediate layer, and the protective layer were provided.

<4,4-thiobis (3-methyl-6-tert-butylphenol)>

  Next, for each reversible thermosensitive recording medium produced, the background density, printing sensitivity, repeated erasure printing test, and light resistance test were performed as follows. The results are shown in Table 2.

<Skin density>
The image density of the background portion of each of the produced reversible thermosensitive recording media was measured with a Macbeth densitometer R914.

<Print sensitivity>
Each reversible thermosensitive recording medium produced was varied in energy by voltage fluctuation (8.0 to 15.5 V) with a constant pulse width of 2.94 msec using a printer manufactured by B.COM. An image with 27 gradations of 27 to 0.66 mj / dot was formed, and an applied energy value that reached a saturation density was calculated by measuring with a Macbeth densitometer R914.

<Repeat erase print test>
Each of the produced reversible thermosensitive recording media was subjected to repeated erasing and printing 100 times using a PCC card printer (R28000), and the surface of the recording medium was visually evaluated. Based on the following evaluation criteria evaluated.
〔Evaluation criteria〕
○: The surface of the recording medium is normal and not scratched.
Δ: Scratches occurred on the surface of the recording medium.
X: Scratches were greatly generated on the surface of the recording medium, and the surface was destroyed.

<Light resistance test>
An image was formed using a card printer (R28000) manufactured by PCC, and left for 300 hours under 5000 Lux irradiation. Thereafter, the entire surface was erased using a PCC card printer (R28000). At this time, the color change of the non-printing portion (color difference between the non-printing portion (background portion) before and after irradiation) is measured with an X light meter, and the unerased portion (image forming portion before irradiation) of the erased portion is measured with a Macbeth densitometer R914. It was measured. The background color difference and the unerased residue were calculated by the following mathematical formula.

From the result of Table 2, Examples 1-11 which contain the phenolic antioxidant containing the sulfur atom which has an alkyl group in one side in a heat sensitive layer are background density, printing sensitivity, compared with Comparative Examples 1-5. It was confirmed that both the repeated erasure print test and the light resistance test had an excellent effect.

  The reversible thermosensitive recording medium of the present invention is used for a prepaid card, a point card, a credit card or the like when processed into a card shape. A sheet size larger than the card size widens the printing range, and can be used for general documents, process management instructions, and the like. Therefore, the reversible thermosensitive recording medium of the present invention can be widely used for large screens and various displays such as entrance / exit tickets, frozen food containers, stickers for industrial products, various chemical containers, logistics management applications, manufacturing process management applications, etc. Can do.

FIG. 1 is a diagram showing color development / decoloration characteristics (color development and decoloration phenomenon) in the reversible thermosensitive recording medium of the present invention. FIG. 2 is a schematic diagram illustrating an example of an RF-ID tag. FIG. 3 is a schematic view showing a state in which an RF-ID tag is bonded to the back layer surface side of the reversible thermosensitive recording medium. FIG. 4A is a schematic diagram illustrating an example of an industrial rewritable sheet (reversible thermosensitive recording medium). FIG. 4B is a schematic diagram illustrating the back surface of FIG. 4A. FIG. 5 is a schematic view showing a method of using an industrial rewritable sheet (reversible thermosensitive recording medium). FIG. 6 is a diagram showing an example of a thermocompression bonding process between the reversible thermosensitive recording label and the base sheet in the present invention. FIG. 7 is a diagram showing another example of the thermocompression bonding process of the reversible thermosensitive recording label and the base sheet according to the present invention. FIG. 8 is a schematic view showing an example of a state in which the reversible thermosensitive recording medium label of the present invention is stuck on an MD disk cartridge. FIG. 9 is a schematic view showing an example of a state in which the reversible thermosensitive recording medium label of the present invention is stuck on an optical information recording medium (CD-RW). FIG. 10 is a schematic cross-sectional view showing an example of a state in which the reversible thermosensitive recording medium label of the present invention is stuck on an optical information recording medium (CD-RW). FIG. 11 is a schematic diagram showing an example of a state in which the reversible thermosensitive recording medium label of the present invention is attached to a video cassette. FIG. 12 is a schematic sectional view showing an example of the layer structure of the reversible thermosensitive recording medium of the present invention. FIG. 13 is a schematic sectional view showing another example of the layer structure of the reversible thermosensitive recording medium of the present invention. FIG. 14A is a schematic view of the surface side of an example of the reversible thermosensitive recording medium of the present invention processed into a card shape. FIG. 14B is a schematic diagram of the back side of FIG. 14A. FIG. 15A is a schematic view of an example in which an example of the reversible thermosensitive recording medium of the present invention is processed into another card shape. FIG. 15B is a schematic view of an IC chip embedded in the IC chip recess of FIG. 15A. FIG. 16A is a schematic configuration block diagram showing an integrated circuit. FIG. 16B is a schematic diagram showing that the RAM includes a plurality of storage areas. FIG. 17 is a schematic diagram showing an example of an image processing apparatus used in the image processing method of the present invention. FIG. 18 is a schematic diagram showing another example of an image processing apparatus used in the image processing method of the present invention. FIG. 19 is a schematic diagram showing still another example of an image processing apparatus used in the image processing method of the present invention. FIG. 20A is a schematic diagram of an image processing apparatus when a surface image is erased by a ceramic heater and an image is formed by a thermal head. FIG. 20B is a schematic diagram illustrating an example of the image processing apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hot plate 2 Mirror surface plate 3 Reversible thermosensitive recording label 4 Base sheet 5 Reversible thermosensitive recording medium 6 Core sheet 7 Oversheet 10 Reversible thermosensitive recording label 11 Support body 13 Thermal layer 14 Intermediate layer 15 Protective layer 16 Back layer 22 Rewriting Recording unit 23 Print display unit 24 Back layer 25 Dimple unit 26 Rewrite recording unit 30 Entrance / exit 31 Transport roller 32 Guide roller 33 Sensor 34 Magnetic head 34c Control unit 35 Platen roller 36 Guide roller 37 Transport roller 38 Ceramic heater 38c Ceramic heater control unit 39 Guide roller 40 Conveying roller 43 Sensor 43a Sensor 44 Platen roller 45 Conveying roller 46 Conveying roller 47 Conveying roller 48 Conveying belt 49b Conveying path 50 Conveying path 51 Sensor 52 Platen roller 53 Thermal 53c Thermal head control means 55a Conveyance path switching means 55b Conveyance path switching means 56a Conveyance path 56b Conveyance path 57a Limit switch 57b Limit switch 58 Conveyance belt 59 Conveyance roller 60 Guide roller 61 Exit 70 MD disk cartridge 71 CD-RW
72 Video cassette 81 IC chip 82 Antenna 85 RF-ID tag 90 Industrial rewritable sheet (reversible thermosensitive recording member)
94 Ceramic heater 95 Thermal head 96 Heat roller 97 Paper feed tray 98 Reversible thermosensitive recording medium (rewritable sheet)
99 RF-ID reader / writer 100 Image processing apparatus 101 Protective layer 102 Thermal layer 103 Support body 104 Back layer 105 Adhesive layer or adhesive layer 106 Intermediate layer 107 Reflective heat dissipation layer 108 Second dielectric layer 109 Optical information storage layer 110 First 1 dielectric layer 111 substrate 112 hard coat layer 231 wafer 232 wafer substrate 233 integrated circuit 234 contact terminal 235 CPU
236 ROM
237 RAM
238 I / O interface 239a to 239g Storage area

Claims (18)

It has a support and at least a heat-sensitive layer on the support, and the heat-sensitive layer contains an electron-donating color-forming compound and an electron-accepting compound, and the color tone reversibly changes depending on the temperature. In addition, the thermosensitive layer contains a phenolic antioxidant which is a compound represented by any one of the following structural formula (1) and the following structural formula (2), and the electron-accepting compound has the following structural formula ( A reversible thermosensitive recording medium, which is a phenol compound represented by any one of a), (b), (c), and (d).
However, in the structural formulas (1) and (2), R ¹ and R ² may be the same as or different from each other, and represent an alkyl group.
  The reversible thermosensitive recording medium according to claim 1, wherein the content of the phenolic antioxidant in the thermosensitive layer is 1 mass% to 10 mass%.   The reversible thermosensitive recording medium according to claim 1, further comprising a polymer-containing layer having an ultraviolet absorbing structure on the thermosensitive layer.   The reversible thermosensitive recording medium according to claim 3, wherein the polymer in the polymer-containing layer having an ultraviolet absorbing structure is crosslinked.   The reversible thermosensitive recording medium according to any one of claims 1 to 4, wherein the reversible thermosensitive recording medium contains an ultraviolet absorber.   The reversible thermosensitive recording medium according to claim 5, wherein the polymer-containing layer having an ultraviolet absorbing structure contains an ultraviolet absorber.   The reversible thermosensitive recording medium according to any one of claims 1 to 6, further comprising an under layer between the thermosensitive layer and the support.   The reversible thermosensitive recording medium according to claim 7, wherein the under layer contains hollow particles.   The reversible thermosensitive recording medium according to any one of claims 1 to 8, wherein the reversible thermosensitive recording medium is in the form of a card, a label, a sheet, or a roll.   10. The irreversible visible information and / or printable part is provided on at least a part of at least one of the image forming surface and the surface opposite to the image forming surface of the reversible thermosensitive recording medium. The reversible thermosensitive recording medium according to any one of the above.   A reversible thermosensitive recording label comprising either an adhesive layer or a pressure-sensitive adhesive layer on a surface opposite to an image forming surface of the reversible thermosensitive recording medium according to any one of claims 1 to 10.   A reversible thermosensitive recording member comprising an information storage unit and a reversible display unit, wherein the reversible display unit comprises the reversible thermosensitive recording medium according to any one of claims 1 to 10.   The reversible thermosensitive recording member according to claim 12, wherein the information storage unit and the reversible display unit are integrated.   The information recording unit is any one selected from a magnetic thermosensitive layer, a magnetic stripe, an IC memory, an optical memory, a hologram, an RF-ID tag card, a disk, a disk cartridge, and a tape cassette. A reversible thermosensitive recording member. An image forming process for forming an image on the reversible thermosensitive recording medium by heating the reversible thermosensitive recording medium, and an image for erasing the image formed on the reversible thermosensitive recording medium by heating the reversible thermosensitive recording medium An image processing method comprising at least one of erasing steps, wherein the reversible thermosensitive recording medium is the reversible thermosensitive recording medium according to any one of claims 1 to 10. The image processing method according to claim 15, wherein the image is formed using either a thermal head or a laser irradiation device. The image processing method according to any one of claims 15 to 16, wherein the image is erased using any one selected from a thermal head, a ceramic heater, a heat roll, a hot stamp, a heat block, and a laser irradiation apparatus. The image processing method according to claim 15, further comprising a step of forming a new image while erasing the image using a thermal head.