JP2006240189A - Reversible thermal recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reversible thermal recording medium which is almost free from a generated dent or a density change, even when the thermal recording medium is repeatedly used, highly durable and has rapid color erasability with practicable thermal head erasure within a broad environmental range from low temperature/low humidity to high temperature/high humidity, and a member which constitutes the recording medium with a reversible thermal recording layer and an information storage part, a label with the reversible thermal recording layer, an image processing method which can form/erase a color developed image in the reversible thermal recording medium, the member and the label, and an image processing device. <P>SOLUTION: This reversible thermal recording medium comprises an electron-donative coloring compound and an electron-receptive compound used on the surface of a support, and comprises the reversible thermal recording layer containing a reversible heat-sensitive composition which can relatively create a color developed state and a color erased state due to the difference in heating temperature and/or the cooling rate after heating, wherein a phenol compound represented by formula (1) is used as the electron-receptive compound. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention has a reversible thermosensitive recording layer using a reversible thermosensitive coloring composition utilizing a coloring reaction between an electron donating color-forming compound and an electron accepting compound, and by controlling thermal energy. Reversible thermosensitive recording medium capable of forming and erasing a color image, member having the reversible thermosensitive recording medium and an information storage unit, reversible thermosensitive recording label having the reversible thermosensitive recording layer, and image processing method using the same And an image processing apparatus.

  2. Description of the Related Art Conventionally, heat-sensitive recording media using a color developing reaction between an electron donating color developing compound (hereinafter also referred to as a color former or a leuco dye) and an electron accepting compound (hereinafter also referred to as a developer) are widely known. With the development of OA, it is widely used as output paper for facsimiles, word processors, scientific measuring instruments, etc., and recently, as magnetic heat sensitive cards such as prepaid cards and point cards. However, these conventional recording media that have been put to practical use are being reviewed for recycling and reduced usage due to environmental problems. However, since they are irreversible colors, once recorded images are erased. It cannot be used repeatedly, and the area of the recordable part is limited because new information is added to the part where no image is recorded. Therefore, the actual situation is that the amount of information to be recorded is reduced or the card is remade when the recording area runs out. Therefore, it has been desired to develop a reversible thermosensitive recording medium that can be rewritten any number of times, against the background of the dust problem and forest destruction problem that have been actively discussed in recent years.

  By the way, various reversible thermosensitive recording media have been proposed from these requirements. For example, polymer-type reversible thermosensitive recording media using physical changes such as transparency and cloudiness are disclosed (see Patent Documents 1 and 2). In addition, a dye-type reversible thermosensitive recording medium utilizing a chemical change has been newly proposed. Specifically, those using a combination of gallic acid and phloroglucinol as a developer (for example, see Patent Document 3), those using a compound such as phenolphthalein or thymolphthalein as a developer (for example, patents) Reference 4), a recording layer containing a homogeneous solution of color former, developer, and carboxylic acid ester (see, for example, Patent Documents 5, 6, and 7), and an ascorbic acid derivative used as the developer (For example, refer to Patent Document 8), and those using a salt of bis (hydroxyphenyl) acetic acid or gallic acid and a higher aliphatic amine as a developer (for example, refer to Patent Documents 9 and 10).

  Furthermore, the present inventors previously used an organic phosphate compound, aliphatic carboxylic acid compound or phenol compound having a long-chain aliphatic hydrocarbon group as a developer in Patent Document 11, and this and a leuco dye which is a color former. In combination, the color development and decoloring can be easily performed under heating and cooling conditions, and the color development state and the color erasure state can be stably maintained at room temperature, and the color development and color erasure are repeated. A reversible thermosensitive coloring composition and a reversible thermosensitive recording medium using the same for a recording layer have been proposed. Thereafter, it has been proposed to use a phenolic compound having a long chain aliphatic hydrocarbon group having a specific structure (see, for example, Patent Documents 12 and 13).

However, the recording medium using such a material has problems such as a slow erasing speed and a long time for rewriting, insufficient erasing, or low thermal stability of a color image.
Therefore, the present inventors further proposed a recording medium having a high contrast between color development and decoloration, capable of high-speed erasing, and excellent in color stability of the image area by using the phenol compound described in Patent Document 14. . The recording medium using this phenolic compound can be erased by a heating member such as a hot stamp, a heat roller, or a ceramic heater, and has excellent practicality.
Furthermore, recording media using these phenolic compounds are excellent in high-speed erasability, and can be erased by heating with a thermal head in a normal temperature and humidity environment, which has the potential of overwriting a thermal head. It was. However, when the compound exemplified in Patent Document 14 is used, the erasability in a low temperature and low humidity environment is deteriorated and erasure cannot be sufficiently performed.

JP 63-107584 A JP-A-4-78573 Japanese Patent Laid-Open No. 60-193691 Japanese Patent Laid-Open No. Sho 61-237684 JP-A-62-138556 JP-A-62-138568 JP-A-62-140881 Japanese Patent Laid-Open No. 63-173684 JP-A-2-188293 JP-A-2-188294 JP-A-5-124360 Japanese Patent Laid-Open No. 6-210954 JP-A-10-95175 JP-A-10-67177

The first object of the present invention is excellent in durability, with little occurrence of indentation and change in density even after repeated use, and in a wide environmental range from low temperature and low humidity to high temperature and high humidity. An object of the present invention is to provide a reversible thermosensitive recording medium excellent in high-speed color erasability capable of thermal head erasing.
The second object of the present invention is to provide a member having the reversible thermosensitive recording medium and an information storage unit, a reversible thermosensitive recording label having a recording layer of the reversible thermosensitive recording medium, an image processing method using these, and An image processing apparatus is provided.

  In the reversible coloring and decoloring phenomenon of such a color former and developer composition, the present inventors have shown that the ability of the developer having a long-chain aliphatic group to develop color and intermolecular aggregation. Considering that balance of force is important, compounds with various structures were studied. As a result, it has been found that the above problem can be solved by using a phenol compound having a specific structure as a developer, and the present invention has been completed.

That is, the said subject is solved by following (1)-(17) of this invention.
(1) “Using an electron-donating color-forming compound and an electron-accepting compound on a support, a relatively colored state and a decolored state are formed depending on the heating temperature and / or the cooling rate after heating. A reversible thermosensitive recording medium having a reversible thermosensitive recording layer containing a reversible thermosensitive composition, wherein a phenol compound represented by the following general formula (1) is used as the electron-accepting compound. recoding media:

（式中、ｋは１から３の整数を、ｍは１から３の整数を示す。ｎは８から２３の整数を示す。また、Ｘ_１およびＸ_２は−ＣＯＮＨ−、−ＮＨＣＯ−、−ＮＨＣＯＮＨ−、−ＣＯＮＨＮＨＣＯ−、−ＣＯＯ−、または−Ｏ−を示し、Ｘ_１とＸ_２は同一でも異なっていてもよい。）」
（２）「前記可逆性感熱記録層中に架橋状態にある樹脂を含有することを特徴とする前記（１）に記載の可逆性感熱記録媒体。」
（３）「前記可逆性感熱記録層中に含有される樹脂が、水酸基価７０（ＫＯＨｍｇ／ｇ）以上であることを特徴とする前記（２）に記載の可逆性感熱記録媒体。」
（４）「前記可逆性感熱記録層中に含有される樹脂が、アクリルポリオール樹脂であることを特徴とする前記（２）又は（３）に記載の可逆性感熱記録媒体。」
（５）「前記可逆性感熱記録層上に該感熱記録層を保護するための保護層を設け、該保護層が架橋状態にある樹脂を含有することを特徴とする前記（１）乃至（４）のいずれかに記載の可逆性感熱記録媒体。」
（６）「前記可逆性感熱記録層上に該感熱記録層を保護するための保護層を設け、該保護層が紫外線吸収性ポリマーを含有することを特徴とする前記（１）乃至（５）のいずれかに記載の可逆性感熱記録媒体。」
（７）「前記可逆性感熱記録層上に該感熱記録層を保護するための保護層を設け、該保護層が紫外線吸収能を有する無機微粒子を含有することを特徴とする前記（１）乃至（５）のいずれかに記載の可逆性感熱記録媒体。」
（８）「情報記憶部と可逆表示部を有し、該可逆表示部が少なくとも前記（１）乃至（７）のいずれかに記載の可逆性感熱記録媒体からなるものであることを特徴とする情報記憶部を有する部材。」
（９）「前記情報記憶部と可逆表示部を有する部材が、カード、ディスク、ディスクカートリッジ又はテープカセットのいずれかであることを特徴とする前記（８）に記載の情報記憶部を有する部材。」
（１０）「前記（１）乃至（７）のいずれかに記載の可逆性感熱記録媒体を構成する支持体の可逆性感熱記録層を形成する面とは反対の面に、接着剤層又は粘着剤層を設けたことを特徴とする可逆性感熱記録ラベル。」
（１１）「前記（１０）に記載の可逆性感熱記録ラベルを用いた可逆表示部が設けられているものであることを特徴とする前記（８）又は（９）に記載の情報記憶部を有する部材。」
（１２）「前記（１）乃至（７）のいずれかに記載の可逆性感熱記録媒体、前記（１０）に記載の可逆性感熱記録ラベル、又は前記（８）、（９）、（１１）のいずれかに記載の情報記憶部と可逆表示部を有する部材を用い、前記可逆性感熱記録層を加熱することにより画像の形成及び／又は消去を行なうことを特徴とする画像処理方法。」
（１３）「サーマルヘッドを用いて前記可逆性感熱記録層に画像を形成することを特徴とする前記（１２）に記載の画像処理方法。」
（１４）「サーマルヘッド又はセラミックヒータを用いて画像を消去することを特徴とする前記（１２）に記載の画像処理方法。」
（１５）「前記（１）乃至（７）のいずれかに記載の可逆性感熱記録媒体、前記（１０）に記載の可逆性感熱記録ラベル又は前記（８）、（９）、（１１）のいずれかに記載の情報記憶部と可逆表示部を有する部材を搭載し、画像の形成及び／又は消去を行なう手段を具備してなることを特徴とする画像処理装置。」
（１６）「前記画像の形成手段がサーマルヘッドであることを特徴とする前記（１５）に記載の画像処理装置。」
（１７）「前記画像の消去手段がサーマルヘッド又はセラミックヒータであることを特徴とする前記（１５）に記載の画像処理装置。」

(In the formula, k represents an integer of 1 to 3, m represents an integer of 1 to 3, n represents an integer of 8 to 23, and X ₁ and X ₂ represent —CONH—, —NHCO—, — NHCONH -, - CONHNHCO -, - COO-, or -O- are shown, _{X 1} and _{X 2} may be the same or different). "
(2) “The reversible thermosensitive recording medium according to (1) above, wherein the reversible thermosensitive recording layer contains a resin in a crosslinked state.”
(3) “The reversible thermosensitive recording medium according to (2) above, wherein the resin contained in the reversible thermosensitive recording layer has a hydroxyl value of 70 (KOHmg / g) or more.”
(4) “The reversible thermosensitive recording medium according to (2) or (3) above, wherein the resin contained in the reversible thermosensitive recording layer is an acrylic polyol resin.”
(5) The above (1) to (4), wherein a protective layer for protecting the thermosensitive recording layer is provided on the reversible thermosensitive recording layer, and the protective layer contains a resin in a crosslinked state. The reversible thermosensitive recording medium according to any one of the above.
(6) “(1) to (5), wherein a protective layer for protecting the thermosensitive recording layer is provided on the reversible thermosensitive recording layer, and the protective layer contains an ultraviolet absorbing polymer. Or a reversible thermosensitive recording medium according to any one of the above.
(7) The above-mentioned (1) to (1), wherein a protective layer for protecting the thermosensitive recording layer is provided on the reversible thermosensitive recording layer, and the protective layer contains inorganic fine particles having ultraviolet absorbing ability. The reversible thermosensitive recording medium according to any one of (5). "
(8) “It has an information storage section and a reversible display section, and the reversible display section is composed of at least the reversible thermosensitive recording medium according to any one of (1) to (7). A member having an information storage unit. "
(9) “The member having the information storage unit according to (8), wherein the member having the information storage unit and the reversible display unit is any one of a card, a disk, a disk cartridge, and a tape cassette. "
(10) "Adhesive layer or adhesive on the surface opposite to the surface forming the reversible thermosensitive recording layer of the support constituting the reversible thermosensitive recording medium according to any one of (1) to (7). A reversible thermosensitive recording label characterized in that an agent layer is provided. "
(11) The information storage unit according to (8) or (9) is provided with a reversible display unit using the reversible thermosensitive recording label according to (10). Member with. "
(12) “The reversible thermosensitive recording medium according to any one of (1) to (7), the reversible thermosensitive recording label according to (10), or (8), (9), (11) An image processing method comprising forming and / or erasing an image by heating the reversible thermosensitive recording layer using a member having an information storage unit and a reversible display unit according to any one of the above items.
(13) “The image processing method according to (12), wherein an image is formed on the reversible thermosensitive recording layer using a thermal head.”
(14) “The image processing method according to (12), wherein the image is erased using a thermal head or a ceramic heater.”
(15) "The reversible thermosensitive recording medium according to any one of (1) to (7), the reversible thermosensitive recording label according to (10) or the above (8), (9), (11)". An image processing apparatus comprising a member having the information storage unit and the reversible display unit according to any one of the above, and means for forming and / or erasing an image.
(16) “The image processing apparatus according to (15), wherein the image forming unit is a thermal head.”
(17) “The image processing apparatus according to (15), wherein the image erasing unit is a thermal head or a ceramic heater.”

The reversible thermosensitive recording medium of the present invention has good color density and excellent high-speed erasability, and also exhibits good high-speed erasability in a wide environmental range from high temperature and high humidity to low temperature and low humidity. In addition, rewriting recording with high practicality can be performed.
In addition, the reversible thermosensitive recording medium having the information storage unit of the present invention, the reversible thermosensitive recording label, the image processing method and the image processing apparatus using these can also exhibit the same excellent effects as described above.

The present invention is described in detail below.
The reversible thermosensitive recording medium using the phenol compound represented by the general formula (1) in the present invention can form a relatively colored state and a decolored state depending on the heating temperature and / or the cooling rate after heating. It is. This basic coloring / decoloring phenomenon will be described.
FIG. 1 shows the relationship between the color density and temperature of the reversible thermosensitive recording medium of the present invention. Introduction gradually heated the recording medium in the decolored state (A), leuco dye and the developer are mixed melt at temperatures T ₁ begins to melt, coloring occurs a molten color developed state (B). When rapidly cooled from the melt color state (B), the color state can be lowered to room temperature and a fixed 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, rapidly cooled colored state (C) is again raised gradually and discoloring occurs at a lower temperature T ₂ than the coloring temperature (E from D), returns the beginning when the temperature decreases from here to the same decolored state (A). 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 of the present invention, the colored state (C) obtained by quenching from the molten state is a state in which the developer and the color former are mixed in a state where they can be contacted with each other, and this is a solid state. Often forms a state. 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 developer are separated and stabilized by aggregation or crystallization. It is done. In many cases, in the present invention, more complete color erasure occurs due to phase separation of the two and crystallization of the developer. In both the decoloring by slow cooling from the molten state and the decoloring by raising the temperature from the colored state shown in FIG. 1, the aggregation structure changes at this temperature, and phase separation and crystallization of the developer occur.

In order to perform erasing in a very short heating time such as thermal head heating, the inventors of the present invention have a rapid crystallization speed of the developer when heated from the colored state (C) to the erasing temperature (T ₂ ). Therefore, various studies were conducted.
As a result, it was found that high-speed erasure can be achieved by introducing a plurality of hydrogen bonding associative groups into the developer molecular structure. This is presumably because the interaction between the developers in the color erasing process is strengthened by a plurality of introduced hydrogen bonding association groups, and the crystallization of the developer is accelerated.
Therefore, the present inventors have proposed the compound described in Patent Document 14 as described above as a phenol compound having a plurality of hydrogen bonding associative groups excellent in high-speed erasability.

However, when such a recording medium is put to practical use, it needs to be usable in various environments, but it has been found that the erasability may be deteriorated particularly in a low temperature and low humidity environment condition, and further in a high temperature and high humidity condition. .
As a result of examining the dependency of erasability on temperature and humidity, the present inventors have found that, among the developer molecular structures, there is a difference in the temperature and humidity dependency of fast erasability, particularly depending on the type of hydrogen bonding associating group and its steric position. I found something. In particular, a structure having an aromatic ring between two hydrogen-bonding associating groups represented by the following general formula (1) enables high-speed erasure by a thermal head, and the erasing characteristics are warm. It was found that it has a good optical density without being affected by humidity.

  Although the detailed reason why high-speed erasure is possible without depending on temperature and humidity is not clear, the intermolecular interaction is strengthened by the π-π stacking interaction between the hydrogen bond site and the aromatic ring directly connected to the hydrogen bond site The reason is that the contribution of the external environment, particularly the influence of water molecules, is small. This is an example that has not been clarified in previous studies, and is the first to be clarified by this study.

（式中、ｋは１から３の整数を、ｍは１から３の整数を示す。ｎは８から２３の整数を示す。また、Ｘ_１およびＸ_２は−ＣＯＮＨ−、−ＮＨＣＯ−、−ＮＨＣＯＮＨ−、−ＣＯＮＨＮＨＣＯ−、−ＣＯＯ−、または−Ｏ−を示し、Ｘ_１とＸ_２は同一でも異なっていてもよい。）
なお、本発明においては、顕色剤として前記一般式（１）で表わされるフェノール化合物を用いるが、本発明の目的を損なわない範囲で可逆性感熱記録媒体の顕色剤として通常用いられている公知の顕色剤を併用してもよい。
以下、表１に本発明において顕色剤として用いる前記一般式（１）で表わされるフェノール化合物の具体的な例を挙げる。

(In the formula, k represents an integer of 1 to 3, m represents an integer of 1 to 3, n represents an integer of 8 to 23, and X ₁ and X ₂ represent —CONH—, —NHCO—, — NHCONH -, - CONHNHCO -, - COO-, or -O- are shown, _{X 1} and _{X 2} may be the same or different).
In the present invention, the phenol compound represented by the general formula (1) is used as a developer, but it is usually used as a developer for a reversible thermosensitive recording medium as long as the object of the present invention is not impaired. A known developer may be used in combination.
Hereinafter, specific examples of the phenol compound represented by the general formula (1) used as a developer in the present invention are shown in Table 1.

  Although the more specific example of the phenol compound shown by Table 1 is shown, it is not limited to these at all.

In the present invention, leuco dyes can be used alone or in combination, and are known dye precursors such as phthalide compounds, azaphthalide compounds, and fluorane compounds.
Specific examples of the leuco dye used in the present invention include the following.
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) fluorane,
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) fluorane,
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-diethylaminofluorane,
1,2-benzo-6-diethylaminofluorane,
3-diethylamino-6- (m-trifluoromethylanilino) 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-methylindol-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.

  The appropriate ratio of the color former to the color developer varies depending on the combination of the compounds to be used. The range is from 2 to 10. If the amount of the developer is less or more than this range, the density of the colored state is lowered, which causes a problem. In addition, the color former and the developer can be used in a microcapsule.

  In the present invention, examples of the binder resin used for forming the reversible thermosensitive recording layer together with the leuco dye and the developer include polyvinyl chloride, polyvinyl acetate, vinyl chloride vinyl acetate copolymer, ethyl cellulose, polystyrene, and styrene-based copolymer. Polymer, phenoxy resin, polyester, aromatic polyester, polyurethane, polycarbonate, polyacrylic acid ester, polymethacrylic acid ester, acrylic acid copolymer, maleic acid copolymer, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, Examples include carboxymethyl cellulose and starches. The role of these binder resins is to keep the materials 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. For example, the binder resin may be crosslinked with heat, ultraviolet light, electron beam, or the like.

  Specific examples of the crosslinked resin used in the present invention include acrylic polyol resin, polyester polyol resin, polyurethane polyol resin, phenoxy resin, polyvinyl butyral resin, cellulose acetate propionate, and cellulose acetate butyrate. A resin having a reactive group, or a resin obtained by copolymerization of a monomer having a group reactive with a crosslinking agent and another monomer may be used, but the present invention is not limited to these compounds.

  Further, in the present invention, a resin having a hydroxyl value of 70 (KOHmg / g) or more is preferably contained (initially used). Examples of the resin having a hydroxyl value of 70 (KOHmg / g) or more include acrylic polyol resins and polyester polyols. Resins, polyurethane polyol resins, and the like are used, and acrylic polyol resins are preferably used because they have particularly good color stability and good decoloring properties. The hydroxyl value is 70 (KOHmg / g) or more, particularly preferably 90 (KOHmg / g) or more. The magnitude of the hydroxyl value affects the crosslink density and thus affects the chemical resistance and physical properties of the coating film. The present inventors have found that durability, coating film surface hardness, and crack resistance are improved when the hydroxyl value is 70 (KOHmg / g) or more. Whether or not the resin is a reversible thermosensitive recording material using a resin having a hydroxyl value of 70 (KOHmg / g) or more can be confirmed by analyzing the amount of residual hydroxyl groups and the amount of ether bonds.

  In addition, acrylic polyol resins have different characteristics depending on the structure. Hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), 2-hydroxyethyl methacrylate (HEMA), 2-hydroxypropyl methacrylate ( HPMA), 2-hydroxybutyl monoacrylate (2-HBA), 1,4-hydroxybutyl monoacrylate (1-HBA), etc. are used, but it is particularly preferable to use a monomer having a primary hydroxyl group. Since the crack resistance and durability are good, 2-hydroxyethyl methacrylate is preferably used.

  Examples of the crosslinking agent used in the present invention include conventionally known isocyanates, amines, phenols, epoxy compounds and the like. Among these, an isocyanate type crosslinking agent is preferably used. The isocyanate compound used here is selected from known modified monomers such as urethane modified products, allophanate modified products, isocyanurate modified products, burette modified products, carbodiimide modified products, and blocked isocyanates. In addition, as the isocyanate monomer forming the modified product, tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), naphthylene diisocyanate NDI), paraphenylene 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. It is not limited to compounds.

  Furthermore, you may use the catalyst used for this kind of reaction as a 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 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 the polymer in the present invention is in a crosslinked state or in a non-crosslinked state, it can be distinguished by immersing the coating film in a highly soluble solvent. That is, since the polymer in the non-crosslinked state dissolves in the solvent and does not remain in the solute, the presence or absence of the polymer structure of the solute may be analyzed.

Further, according to the present invention, a protective layer containing a resin in a crosslinked state can be provided on the reversible thermosensitive recording layer. As the resin used for the protective layer, the same thermosetting resin, ultraviolet curable resin, and electron beam curable resin as those used for the recording layer are used.
As the resin used in the protective layer, an ultraviolet absorbing polymer having an ultraviolet absorbing group in the molecular structure is particularly preferably used.
As the ultraviolet absorbing polymer, a monomer having an ultraviolet absorbing group and a polymer having a monomer having a crosslinkable functional group are preferably used. As the monomer having an ultraviolet absorbing group, (2 '-Hydroxy-5'-methacryloxyethylphenyl) -2H-benzotriazole, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3'-ω-butyl- A monomer having a benzotriazole skeleton such as 5′-methylphenyl) -5-chlorobenzotriazole is particularly preferably used.

  Examples of the monomer containing a functional group include 2-isopropenyl-2-oxazoline, 2-aziridinylethyl (meth) acrylate, methacrylic acid, glycidyl (meth) acrylate, hydroxylethyl (meth) acrylate, hydroxyl Examples include propyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, and tetrahydrofurfuryl (meth) acrylate, among which hydroxylethyl (meth) ) Acrylate, hydroxylpropyl (meth) acrylate and the like are particularly preferably used.

  Furthermore, in order to increase the strength of the coating film and improve heat resistance, the following monomers may be copolymerized with a copolymer of a monomer containing an ultraviolet absorbing group and a monomer containing a functional group. For example, monomers such as styrene, styrene-butadiene, styrene-isobutylene, ethylene vinyl acetate, vinyl acetate, methacrylonitrile, vinyl alcohol, vinyl pyrrolidone, acrylonitrile, methacrylonitrile; acrylic acid, methyl (meth) acrylate, ethyl (meth ) Acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, ethylhexyl (meth) acrylate, octyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) ) Acrylate, lauryl tridecyl (meth) acrylate, tridecyl (meth) acrylate, cetyl stearyl (meth) acrylate, stearyl (meth) acrylate (Meth) acrylic acid ester groups not containing functional groups such as cyclohexyl (meth) acrylate and benzyl (meth) acrylate; ethylene di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene Glycol di (meth) acrylate, decaethylene glycol di (meth) acrylate, pentacontahector ethylene glycol (meth) acrylate, butylene di (meth) acrylate, pentaerythritol tetra (meth) acrylate, trimethylolpropane tri (meth) acrylate, penta Decaethylene glycol di (meth) acrylate, phthalic acid diethylene glycol di (meth) acrylate, etc. have two or more polymerizable double bonds in one molecule Although it is mentioned from a monomer group etc., it is not particularly limited, among them, styrene, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, Particularly preferred is t-butyl (meth) acrylate. Moreover, 2 or more types can also be used together as needed.

  From the above, specific preferred examples of the polymer having an ultraviolet absorption structure used in the present invention include 2- (2′-hydroxy-5′-methacryloxyethylphenyl) -2H-benzotriazole and 2-hydroxy methacrylate. Examples include a copolymer composed of ethyl and styrene, and a copolymer composed of 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2-hydroxypropyl methacrylate and methyl methacrylate. Is not to be done.

Furthermore, according to the present invention, the protective layer can contain inorganic fine particles having ultraviolet absorbing ability.
The inorganic pigment used in the present invention is arbitrary as long as it has an average particle size of 0.1 μm or less. Examples of such inorganic pigments include zinc oxide, indium oxide, alumina, silica, zirconium oxide, tin oxide, cerium oxide, iron oxide, antimony oxide, barium oxide, calcium oxide, bismuth oxide, nickel oxide, magnesium oxide, chromium oxide, Metal oxides such as manganese oxide, tantalum oxide, niobium oxide, thorium oxide, hafnium oxide, molybdenum oxide, iron ferrite, nickel ferrite, cobalt ferrite, barium titanate, potassium titanate and complex oxides thereof, zinc sulfide, Metal sulfides such as barium sulfate or sulfate compounds, titanium carbide, silicon carbide, molybdenum carbide, tungsten carbide, metal carbides such as tantalum carbide, aluminum nitride, silicon nitride, boron nitride, nitride Rukoniumu, vanadium nitride, titanium nitride, niobium nitride, and metal nitrides such as gallium nitride.

Among these, a pigment having an absorption edge in a wavelength region of 400 nm or less is particularly preferable.
Such a pigment includes a pigment (A) having an absorption edge in the ultraviolet UV-A region, that is, an ultraviolet UV-A region having a wavelength of 320 to 400 nm, and an inorganic pigment having an absorption edge on the shorter wavelength side than the ultraviolet UV-A region ( B) can be classified into two groups. In the present invention, the inorganic pigment (A) or the inorganic pigment (B) can be used alone, but the effect of the present invention becomes more remarkable by using the inorganic pigment (A) and the inorganic pigment (B) in combination. When the inorganic pigment (A) or the inorganic pigment (B) is used alone, these pigments can be contained in either the intermediate layer or the protective layer. In the case where the inorganic pigment (A) and the inorganic pigment (B) are used in combination, these pigments can be simultaneously contained in the intermediate layer or the protective layer, but the inorganic pigment (A) and the inorganic pigment (B) are included in the intermediate layer. And can be contained separately in the protective layer. In this case, when the inorganic pigment (A) is contained in the intermediate layer and the inorganic pigment (B) is contained in the protective layer, the effect of the present invention is more remarkably exhibited.
Specific examples of the inorganic pigment (A) include zinc sulfide, titanium oxide, indium oxide, cerium oxide, tin oxide, molybdenum oxide, zinc oxide, and gallium nitride.
Specific examples of the inorganic pigment (B) include silica, alumina, silica-alumina, antimony oxide, magnesium oxide, zirconium oxide, barium oxide, calcium oxide, strontium oxide, silicon nitride, aluminum nitride, boron nitride, and barium sulfate. Can be mentioned.

  Further, in the present invention, inorganic / organic fillers, lubricants and the like used for this type of recording medium may be used in the protective layer.

The support of the reversible thermosensitive recording medium of the present invention is paper, resin film, PET film, synthetic paper, metal foil, glass or a composite thereof, and the like, as long as it can hold the reversible thermosensitive recording layer. Good. Moreover, the thing of the thickness as needed can be used individually or by bonding. That is, it is preferably 60 to 150 μm, and a support having an arbitrary thickness from about several μm to about several mm is used.
Moreover, when providing an under layer on these support bodies, crack generation prevention and generation | occurrence | production of a burr | flash are improved by providing through an contact bonding layer.
The adhesive layer can be formed by the same coating method as that for each of the above layers.

The reversible thermosensitive recording label of the present invention is one in which an adhesive layer or a pressure-sensitive adhesive layer is provided on the surface opposite to the surface on which the thermosensitive recording layer of the support constituting the reversible thermosensitive recording medium is formed.
This reversible thermosensitive recording label includes an adhesive layer or a pressure-sensitive adhesive layer (non-peeling paper type), and a release paper attached under the adhesive layer or pressure-sensitive adhesive layer (peeling paper type). As a material constituting the adhesive layer, a hot melt type material is usually used.
Commonly used materials can be used for the adhesive layer or the pressure-sensitive adhesive layer.
For example, urea resin, melamine resin, phenol resin, epoxy resin, vinyl acetate resin, vinyl acetate-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 resins, silicon resins, and the like, but are not limited thereto.

The reversible thermosensitive recording medium of the present invention functions as a reversible display unit that functions as at least a thermosensitive recording layer constituting the reversible thermosensitive recording medium, and information produced by combining it with a member (information storage unit) having an information storage function. It can be used as a display storage member.
Next, the information display storage member will be described.
The members having the information storage unit and the reversible display unit can be roughly classified into the following three items.
(1) A part of a member having an information storage function is used as a support for a reversible thermosensitive recording medium, and a thermosensitive recording layer is directly formed thereon.
(2) A member having an information storage function, wherein a support surface of a reversible thermosensitive recording medium which is separately formed and has a thermosensitive recording layer on the support is bonded.
(3) The reversible thermosensitive recording label bonded to a member having an information storage function via an adhesive layer or an adhesive layer.
In these cases (1), (2), and (3), 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 are set. The position can be arbitrarily selected according to the purpose, and the reversible thermosensitive recording medium can be provided on the surface opposite to the surface on which the thermosensitive recording layer is provided, between the support and the thermosensitive recording layer, or thermosensitive. It can also be provided on a part of the recording layer.
The member having the information storage function is not particularly limited, and a general card, disk, disk cartridge, or tape cassette can be used.

Examples of these include thick cards such as IC cards and optical cards, flexible disks, magneto-optical recording disks (MD), disk cartridges with built-in disks that can rewrite storage information such as DVD-RAM, and CD-RWs. Examples thereof include a disc that does not use a disc 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. Examples thereof are shown in FIGS.
The information display storage member having both the reversible display function and the information storage function will be described in the case of a card, for example, by displaying a part of the information stored in the information storage unit on the reversible thermosensitive recording layer. The owner or the like can confirm information by looking at the card without a special device, and the convenience is greatly improved compared to 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. For example, magnetic recording, contact IC, non-contact IC, or optical memory is useful.
The magnetic recording layer is formed by coating the support using a commonly used metal compound such as iron oxide or barium ferrite and a resin such as vinyl chloride, urethane or nylon, or without using a resin. It forms by methods, such as vapor deposition and sputtering, using the said metal compound. Further, the reversible thermosensitive recording layer in the reversible thermosensitive recording medium used for display can also be used as a storage unit in a manner such as a barcode or a two-dimensional code.

In addition, as an example of using the reversible thermosensitive recording label of (3) above, when the reversible thermosensitive recording layer is difficult to apply as a support, such as a vinyl chloride card with a magnetic stripe, An adhesive layer or a pressure-sensitive adhesive layer can be provided on the entire surface or a part thereof.
By doing so, the convenience of this medium can be improved, such as being able to display a part of the information stored in the magnetism.
The reversible thermosensitive recording label provided with the adhesive layer or the pressure-sensitive adhesive layer is applicable not only to the above-described magnetic PVC card but also to a thick card such as an IC card or an optical card.

Further, the reversible thermosensitive recording label can be used in place of a display label on a disk cartridge having a built-in rewritable disk such as a flexible disk, MD or DVD-RAM.
Further, in the case of a disc that does not use a disc cartridge such as a CD-RW, a reversible thermosensitive recording label can be directly attached to the disc, or a reversible thermosensitive recording layer can be provided directly on the disc. By doing so, it is possible to apply to applications such as automatically changing display contents in accordance with changes in the stored contents.

The reversible thermosensitive recording label of the present invention can also be displayed by rewriting a part of the stored information added to the CD-R by sticking the reversible thermosensitive recording label on a write-once disc such as a CD-R.
Further, it may be used as a display label for a video tape cassette.
As a method of providing a thermoreversible recording function on a thick card, a disc cartridge, and a disc, in addition to the method of applying the reversible thermosensitive recording label, a method of directly applying a reversible thermosensitive recording layer on them, There is a method of forming a reversible thermosensitive recording layer on the support and transferring the thermosensitive recording layer onto a thick card, a disc cartridge, or a disc.
When transferring, an adhesive layer such as a hot melt type or an adhesive layer may be provided on the reversible thermosensitive recording layer.
When attaching a reversible thermosensitive recording label or providing a reversible thermosensitive recording layer on a rigid object such as a thick card, disk, disk cartridge, tape cassette, etc., improve the contact with the thermal head. In order to form an image uniformly, it is preferable to provide a cushioning layer or sheet between the rigid substrate and the label or the reversible thermosensitive recording layer.

  The present invention further provides an image processing method, wherein the reversible thermosensitive recording medium, the member having the information storage unit or the label is used to form and / or erase an image by heating. A schematic diagram of an example of the image processing method / apparatus of the present invention is shown in FIG.

For image formation, an image recording means such as a thermal head, a laser or the like that can partially heat the medium on the image is used. For erasing the image, an image erasing means such as a hot stamp, a ceramic heater, a heat roller, hot air, a thermal head, or a laser is used.
Among these, a ceramic heater is preferably used. By using a ceramic heater, the apparatus can be miniaturized, a stable erased state can be obtained, and an image with good contrast can be obtained.
The set temperature of the ceramic heater is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, and even more preferably 115 ° C. or higher.
Further, by using a thermal head as the image erasing means, it is possible to further reduce the size of the entire apparatus, to reduce power consumption, and to realize a battery-driven handy type apparatus. If a single thermal head is used for both forming and erasing, the size can be further reduced.
When forming and erasing with a single thermal head, once the previous image has been erased, a new image may be formed again. The energy is changed for each image, and the previous image is erased at one time. It is also possible to use an overwrite method that forms the film.
In the overwrite method, the time required for forming and erasing the image is reduced, and the recording speed is increased. In the case of using a card having a reversible thermosensitive recording layer and an information storage unit, the above device includes means for reading and rewriting the memory of the information storage unit.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In the text, “part” or “%” is based on weight unless otherwise specified.

  First, a typical synthesis example of a phenol compound used in the present invention is shown. The phenol compounds mentioned in Examples 2 and 3 were synthesized by the same method except that the raw material stearic acid was changed to behenic acid and palmitic acid, respectively. The phenol compound of the present invention is not limited to this synthesis method.

Synthesis Example (Synthesis of developer expressed by the following structural formula)

テトラヒドロフラン３００ｍＬにステアリン酸１３．６ｇとヒドロキシベンゾトリアゾール６．５ｇを加え、０．５時間攪拌、還流した。その溶液にジイソプロピルカルボジイミド６．３ｇを加え、その懸濁液を３０分攪拌、還流した。その懸濁液に４−アミノ安息香酸６．５ｇを加え、３時間攪拌した。室温に戻し、ろ過により固形物を取り出した。メチルエチルケトンにより再結晶を行うことで化合物４−ステアロイルアミノ安息香酸を得た。収量１３．４ｇ、収率６７％であった。このときの融点は１６５℃であった。ついで、テトラヒドロフランに４−ステアロイルアミノ安息香酸４．０ｇとヒドロキシベンゾトリアゾール１．２９ｇを加え、０．５時間攪拌、還流した。その懸濁液にジイソプロピルカルボジイミド１．２１ｇを加え、その懸濁液を３０分攪拌、還流した。その懸濁液にチラミン１．３１ｇを加え、３時間攪拌した。室温に戻し、１Ｎ塩酸水溶液を加え、ろ過により固形物を取り出した。２−プロパノールにより再結晶を行い、熱ろ過によってエタノールにより再結晶を行い、上記構造式で表わされる化合物を得た。（収量：２．２ｇ、収率：４３％、融点２２１℃）

To 300 mL of tetrahydrofuran were added 13.6 g of stearic acid and 6.5 g of hydroxybenzotriazole, and the mixture was stirred and refluxed for 0.5 hours. To the solution was added 6.3 g of diisopropylcarbodiimide, and the suspension was stirred and refluxed for 30 minutes. To the suspension, 6.5 g of 4-aminobenzoic acid was added and stirred for 3 hours. It returned to room temperature and the solid substance was taken out by filtration. The compound 4-stearoylaminobenzoic acid was obtained by recrystallization with methyl ethyl ketone. The yield was 13.4 g and the yield was 67%. The melting point at this time was 165 ° C. Next, 4.0 g of 4-stearoylaminobenzoic acid and 1.29 g of hydroxybenzotriazole were added to tetrahydrofuran, and the mixture was stirred and refluxed for 0.5 hour. To the suspension was added 1.21 g of diisopropylcarbodiimide, and the suspension was stirred and refluxed for 30 minutes. To the suspension, 1.31 g of tyramine was added and stirred for 3 hours. It returned to room temperature, 1N hydrochloric acid aqueous solution was added, and solid substance was taken out by filtration. Recrystallization with 2-propanol and recrystallization with ethanol by hot filtration yielded the compound represented by the above structural formula. (Yield: 2.2 g, Yield: 43%, melting point 221 ° C.)

Example 1
[Creation of reversible thermosensitive recording layer]
4 parts of developer expressed by the following structural formula

アクリルポリオール樹脂
（三菱レイヨン社製ＬＲ５０３、固形分濃度５０％溶液） ９部
メチルエチルケトン ７０部
上記組成物をボールミルを用いて平均粒径約１μｍまで粉砕分散した。得られた分散液に２−アニリノ−３−メチル−６−ジエチルアミノフルオラン１部、日本ポリウレタン社製コロネートＨＬ（アダクト型ヘキサメチレンジイソシアネート７５％酢酸エチル溶液）２部を加え、良く攪拌し感熱記録層塗布液を調製した。
上記組成の感熱記録層塗布液を、厚さ１８８μｍの白ＰＥＴにワイヤーバーを用い塗布し、１００℃２分で乾燥した後、６０℃２４時間加熱して、膜厚約８．０μｍの感熱記録層を設けた。

Acrylic polyol resin (LR503 manufactured by Mitsubishi Rayon Co., Ltd., 50% solid content solution) 9 parts Methyl ethyl ketone 70 parts The above composition was pulverized and dispersed to an average particle size of about 1 µm using a ball mill. To the obtained dispersion, 1 part of 2-anilino-3-methyl-6-diethylaminofluorane and 2 parts of Coronate HL (Adduct type hexamethylene diisocyanate 75% ethyl acetate solution) manufactured by Nippon Polyurethane Co., Ltd. were added and stirred well. A layer coating solution was prepared.
The thermosensitive recording layer coating solution having the above composition was applied to white PET having a thickness of 188 μm using a wire bar, dried at 100 ° C. for 2 minutes, and then heated at 60 ° C. for 24 hours to give a thermal recording with a film thickness of about 8.0 μm. A layer was provided.

[Create protection layer]
40% solution of UV-absorbing polymer (UV-G300 manufactured by Nippon Shokubai Co., Ltd.) 10 parts Isocyanate-based crosslinking agent (manufactured by Nihon Polyurethane, Coronate HX) 1.4 parts Silicone-based acrylic resin (GS-1015 manufactured by Toagosei Co., Ltd.) 0 .5 parts Methyl ethyl ketone 10 parts The above composition was well stirred to prepare a protective layer coating solution.
A protective layer coating solution having the above composition is applied onto the thermal recording layer using a wire bar, dried at 100 ° C. for 2 minutes, and then heated at 60 ° C. for 24 hours to provide a protective layer having a thickness of about 3.5 μm. A reversible thermosensitive recording medium of the present invention was produced.

Example 2
A reversible thermosensitive recording medium was prepared in the same manner as in Example 1 except that the following coating solution was used instead of the thermosensitive recording layer coating solution used in Example 1.
[Thermosensitive recording layer coating solution]
4 parts of developer expressed by the following structural formula

アクリルポリオール樹脂
（三菱レイヨン社製ＬＲ５０３、固形分濃度５０％溶液） ９部
メチルエチルケトン ７０部
上記組成物をボールミルを用いて平均粒径約１μｍまで粉砕分散した。得られた分散液に２−アニリノ−３−メチル−６−ジエチルアミノフルオラン１部、日本ポリウレタン社製コロネートＨＬ（アダクト型ヘキサメチレンジイソシアネート７５％酢酸エチル溶液）２部を加え、良く攪拌し感熱記録層塗布液を調製した。

Acrylic polyol resin (LR503 manufactured by Mitsubishi Rayon Co., Ltd., 50% solid content solution) 9 parts Methyl ethyl ketone 70 parts The above composition was pulverized and dispersed to an average particle size of about 1 µm using a ball mill. To the obtained dispersion, 1 part of 2-anilino-3-methyl-6-diethylaminofluorane and 2 parts of Coronate HL (Adduct type hexamethylene diisocyanate 75% ethyl acetate solution) manufactured by Nippon Polyurethane Co., Ltd. were added and stirred well. A layer coating solution was prepared.

Example 3
A reversible thermosensitive recording medium was prepared in the same manner as in Example 1 except that the following coating solution was used instead of the thermosensitive recording layer coating solution used in Example 1.
[Thermosensitive recording layer coating solution]
4 parts of developer expressed by the following structural formula

アクリルポリオール樹脂
（三菱レイヨン社製ＬＲ５０３、固形分濃度５０％溶液） ９部
メチルエチルケトン ７０部
上記組成物をボールミルを用いて平均粒径約１μｍまで粉砕分散した。得られた分散液に２−アニリノ−３−メチル−６−ジエチルアミノフルオラン１部、日本ポリウレタン社製コロネートＨＬ（アダクト型ヘキサメチレンジイソシアネート７５％酢酸エチル溶液）２部を加え、良く攪拌し感熱記録層塗布液を調製した。

Acrylic polyol resin (LR503 manufactured by Mitsubishi Rayon Co., Ltd., 50% solid content solution) 9 parts Methyl ethyl ketone 70 parts The above composition was pulverized and dispersed to an average particle size of about 1 µm using a ball mill. To the obtained dispersion, 1 part of 2-anilino-3-methyl-6-diethylaminofluorane and 2 parts of Coronate HL (Adduct type hexamethylene diisocyanate 75% ethyl acetate solution) manufactured by Nippon Polyurethane Co., Ltd. were added and stirred well. A layer coating solution was prepared.

Comparative Example 1
A reversible thermosensitive recording medium was prepared in the same manner as in Example 1 except that the following coating solution was used instead of the thermosensitive recording layer coating solution used in Example 1.
[Thermosensitive recording layer coating solution]
4 parts of developer expressed by the following structural formula

アクリルポリオール樹脂
（三菱レイヨン社製ＬＲ５０３、固形分濃度５０％溶液） ９部
メチルエチルケトン ７０部
上記組成物をボールミルを用いて平均粒径約１μｍまで粉砕分散した。得られた分散液に２−アニリノ−３−メチル−６−ジエチルアミノフルオラン１部、日本ポリウレタン社製コロネートＨＬ（アダクト型ヘキサメチレンジイソシアネート７５％酢酸エチル溶液）２部を加え、良く攪拌し感熱記録層塗布液を調製した。

Acrylic polyol resin (LR503 manufactured by Mitsubishi Rayon Co., Ltd., 50% solid content solution) 9 parts Methyl ethyl ketone 70 parts The above composition was pulverized and dispersed to an average particle size of about 1 µm using a ball mill. To the obtained dispersion, 1 part of 2-anilino-3-methyl-6-diethylaminofluorane and 2 parts of Coronate HL (Adduct type hexamethylene diisocyanate 75% ethyl acetate solution) manufactured by Nippon Polyurethane Co., Ltd. were added and stirred well. A layer coating solution was prepared.

Comparative Example 2
A reversible thermosensitive recording medium was prepared in the same manner as in Example 1 except that the following coating solution was used instead of the thermosensitive recording layer coating solution used in Example 1.
[Thermosensitive recording layer coating solution]
4 parts of developer expressed by the following structural formula

アクリルポリオール樹脂
（三菱レイヨン社製ＬＲ５０３、固形分濃度５０％溶液） ９部
メチルエチルケトン ７０部
上記組成物をボールミルを用いて平均粒径約１μｍまで粉砕分散した。得られた分散液に２−アニリノ−３−メチル−６−ジエチルアミノフルオラン１部、日本ポリウレタン社製コロネートＨＬ（アダクト型ヘキサメチレンジイソシアネート７５％酢酸エチル溶液）２部を加え、良く攪拌し感熱記録層塗布液を調製した。

Acrylic polyol resin (LR503 manufactured by Mitsubishi Rayon Co., Ltd., 50% solid content solution) 9 parts Methyl ethyl ketone 70 parts The above composition was pulverized and dispersed to an average particle size of about 1 µm using a ball mill. To the obtained dispersion, 1 part of 2-anilino-3-methyl-6-diethylaminofluorane and 2 parts of Coronate HL (Adduct type hexamethylene diisocyanate 75% ethyl acetate solution) manufactured by Nippon Polyurethane Co., Ltd. were added and stirred well. A layer coating solution was prepared.

Comparative Example 3
A reversible thermosensitive recording medium was prepared in the same manner as in Example 1 except that the following coating solution was used instead of the thermosensitive recording layer coating solution used in Example 1.
[Thermosensitive recording layer coating solution]
4 parts of developer expressed by the following structural formula

アクリルポリオール樹脂
（三菱レイヨン社製ＬＲ５０３、固形分濃度５０％溶液） ９部
メチルエチルケトン ７０部
上記組成物をボールミルを用いて平均粒径約１μｍまで粉砕分散した。得られた分散液に２−アニリノ−３−メチル−６−ジエチルアミノフルオラン１部、日本ポリウレタン社製コロネートＨＬ（アダクト型ヘキサメチレンジイソシアネート７５％酢酸エチル溶液）２部を加え、良く攪拌し感熱記録層塗布液を調製した。

Acrylic polyol resin (LR503 manufactured by Mitsubishi Rayon Co., Ltd., 50% solid content solution) 9 parts Methyl ethyl ketone 70 parts The above composition was pulverized and dispersed to an average particle size of about 1 µm using a ball mill. To the obtained dispersion, 1 part of 2-anilino-3-methyl-6-diethylaminofluorane and 2 parts of Coronate HL (Adduct type hexamethylene diisocyanate 75% ethyl acetate solution) manufactured by Nippon Polyurethane Co., Ltd. were added and stirred well. A layer coating solution was prepared.

  The following evaluation was performed on the reversible thermosensitive recording media prepared in each Example and Comparative Example. The results are shown in Table 3.

<Coloring / decoloring density>
Each reversible thermosensitive recording medium was printed under the conditions of a voltage of 18 V and a pulse width of 2 msec using a thermal printing simulator manufactured by B.COM in an environment of an air temperature of 23 ° C. and a humidity of 50% RH, and a belt-like print sample was produced. The density and the background density were measured using a Macbeth densitometer RD914.
The obtained print sample was erased in steps of 0.5 V from a voltage of 6 V to 13.5 V under the condition of a pulse width of 6 msec, and the density was measured in the same manner, and the lowest density was defined as the decolored density.
Next, the above coloring and decoloring tests were similarly performed in a low-temperature and low-humidity environment with an air temperature of 5 ° C. and a humidity of 30% RH, and a high-temperature and high-humidity environment with an air temperature of 30 ° C. and a humidity of 90% RH. And the decoloring density was measured.

It is a figure which shows the color development and decoloring characteristic of the reversible thermosensitive recording medium of this invention. It is a figure which shows the example which affixed the reversible thermosensitive recording label of this invention on the disk cartridge of MD. It is a figure which shows the example which affixed the reversible thermosensitive recording label of this invention on CD-RW. It is a figure which shows the example which used the reversible thermosensitive recording label of this invention as a display label of a videotape cassette. It is the schematic which shows the example of the image processing method and apparatus of this invention.

Explanation of symbols

34 Magnetic head 38 Ceramic heater 40 Transport roller 47 Transport roller 53 Thermal head

Claims (17)

A reversible thermosensitive material that uses an electron-donating color-forming compound and an electron-accepting compound on a support to form a relatively colored state and a decolored state depending on the heating temperature and / or the cooling rate after heating. A reversible thermosensitive recording medium having a reversible thermosensitive recording layer containing the composition, wherein a phenol compound represented by the following general formula (1) is used as the electron-accepting compound.

(In the formula, k represents an integer of 1 to 3, m represents an integer of 1 to 3, n represents an integer of 8 to 23, and X ₁ and X ₂ represent —CONH—, —NHCO—, — NHCONH -, - CONHNHCO -, - COO-, or -O- are shown, _{X 1} and _{X 2} may be the same or different). 2. The reversible thermosensitive recording medium according to claim 1, wherein the reversible thermosensitive recording layer contains a resin in a crosslinked state. The reversible thermosensitive recording medium according to claim 2, wherein the resin contained in the reversible thermosensitive recording layer has a hydroxyl value of 70 (KOHmg / g) or more. The reversible thermosensitive recording medium according to claim 2 or 3, wherein the resin contained in the reversible thermosensitive recording layer is an acrylic polyol resin. The protective layer for protecting the thermosensitive recording layer is provided on the reversible thermosensitive recording layer, and the protective layer contains a resin in a crosslinked state. Reversible thermosensitive recording medium. 6. The reversible according to claim 1, wherein a protective layer for protecting the thermosensitive recording layer is provided on the reversible thermosensitive recording layer, and the protective layer contains an ultraviolet absorbing polymer. Sexual thermal recording medium. 6. The protective layer for protecting the thermosensitive recording layer is provided on the reversible thermosensitive recording layer, and the protective layer contains inorganic fine particles having an ultraviolet absorbing ability. The reversible thermosensitive recording medium described. A member having an information storage unit, comprising an information storage unit and a reversible display unit, wherein the reversible display unit comprises at least the reversible thermosensitive recording medium according to claim 1. 9. The member having an information storage unit according to claim 8, wherein the member having the information storage unit and the reversible display unit is any one of a card, a disk, a disk cartridge, and a tape cassette. An adhesive layer or a pressure-sensitive adhesive layer is provided on a surface opposite to a surface on which the reversible thermosensitive recording layer of the support constituting the reversible thermosensitive recording medium according to any one of claims 1 to 7 is formed. Features a reversible thermosensitive recording label. The member having an information storage unit according to claim 8 or 9, wherein a reversible display unit using the reversible thermosensitive recording label according to claim 10 is provided. The reversible thermosensitive recording medium according to any one of claims 1 to 7, the reversible thermosensitive recording label according to claim 10, or the information storage unit and the reversible display unit according to any one of claims 8, 9, and 11. An image processing method comprising: forming and / or erasing an image by heating the reversible heat-sensitive recording layer using a member having The image processing method according to claim 12, wherein an image is formed on the reversible thermosensitive recording layer using a thermal head. The image processing method according to claim 12, wherein the image is erased using a thermal head or a ceramic heater. The reversible thermosensitive recording medium according to any one of claims 1 to 7, the reversible thermosensitive recording label according to claim 10, or the information storage unit and the reversible display unit according to any one of claims 8, 9, and 11. An image processing apparatus comprising: a member having a member mounted thereon; and means for forming and / or erasing an image. The image processing apparatus according to claim 15, wherein the image forming unit is a thermal head. The image processing apparatus according to claim 15, wherein the image erasing means is a thermal head or a ceramic heater.

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