JP4467008B2 - Reversible thermosensitive recording medium, image processing method and image processing apparatus using the same - Google Patents

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. The present invention relates to a reversible thermosensitive recording medium capable of forming and erasing a color image, an image processing method and an image processing apparatus using the reversible thermosensitive recording medium.

  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 phenol 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, when producing a reversible thermosensitive recording medium using these phenolic compounds, a coloring / decoloring control agent aimed at improving decoloring property and improving image stability for enhancing practicality, Accelerators have been studied, and by using the long-chain alkyl compounds described in Patent Documents 15, 16, 17 and the like, the erasability is improved and almost no unerased residue is generated. By using the long-chain alkyl compound, improved color erasability and a stable color image were obtained.
However, the reversible thermosensitive recording medium using the long-chain alkyl compound described in Patent Documents 15, 16 and 17 can be erased satisfactorily in a room temperature environment, but the erasability is lowered particularly in a low temperature and low humidity environment. There was a problem.

Further, Patent Documents 18, 19, etc. have improved decoloring properties such as high-speed erasability by using a compound having an ether group and an amide group as a coloring / decoloring control agent or decoloring accelerator. Has been proposed.
However, the reversible thermosensitive recording media using the compounds having an ether group and an amide group described in Patent Documents 18 and 19 also have a problem that the erasability is particularly insufficient in a low temperature and low humidity environment.

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 Japanese Patent Laid-Open No. 9-48715 Japanese Patent Laid-Open No. 9-290563 Japanese Patent Laid-Open No. 11-70731 Japanese Patent No. 3544429 JP 2002-86921 A

  The present invention provides a reversible thermosensitive recording medium excellent in erasability in a low-temperature and low-humidity environment, and an image processing method and an image processing apparatus for forming and / or erasing an image using the reversible thermosensitive recording medium. That is.

  In the color erasing process of the reversible color erasing phenomenon of such a color developer and developer composition, the present inventors have developed a color developer and a leuco dye having a long-chain aliphatic group that forms a colored state. In addition, the balance of intermolecular cohesion between the color development / decoloration control agent or the decolorization accelerator is important, and if the intermolecular cohesion is too strong, the erasability in a low-temperature and low-humidity environment will decrease. A study was conducted. As a result, it has been found that the above-mentioned problems can be solved by using an ether group-containing amide compound having a specific structure as a coloring / decoloring control agent, and the present invention has been completed.

That is, the said subject is solved by following (1)-( 13 ) 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 depending on the difference in heating temperature and / or cooling rate after heating. A reversible thermosensitive recording medium having a reversible thermosensitive recording layer which can be formed, wherein an ether group-containing amide compound represented by the following general formula (1) is used as a coloring / decoloring control agent.

（式中、ｌは０から３の整数を、ｍは３を、ｎは１２から１６の整数を示す。）
」；
（２）「前記可逆性感熱記録層中に、架橋状態にある樹脂を含む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中に含有される樹脂が、イソシアネート化合物によって架橋されていることを特徴とする前記（２）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（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（６）のいずれかに記載の可逆性感熱記録媒体」；
（８）「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（７）のいずれかに記載の可逆性感熱記録媒体」；
（９）「情報記憶部を設けたことを特徴とする前記（１）乃至（８）のいずれかに記載の可逆性感熱記録媒体」；
（１０）「前記支持体の可逆性感熱記録層を設けた面と反対の面に、接着剤層又は粘着剤層を設けたことを特徴とする前記（１）乃至（９）のいずれかに記載の可逆性感熱記録媒体」；
（１１）「前記（１）乃至（１０）のいずれかに記載の可逆性感熱記録媒体を用いて、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」；
（１２）「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（１１）に記載の画像処理方法」；
（１３）「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（１１）に記載の画像処理方法」。

(In the formula, l represents an integer from 0 to 3 , m represents 3 , and n represents an integer from 12 to 16. )
";
(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 reversible thermosensitive recording medium according to any one of (2) to (4) above, wherein the resin contained in the reversible thermosensitive recording layer is crosslinked with an isocyanate compound”. ;
(6) “Reversible feeling according to any one of (1) to (5) above, wherein a protective layer is provided on the reversible thermosensitive recording layer, and the protective layer contains a resin in a crosslinked state. Thermal recording medium ";
(7) “Reversible thermosensitive recording according to any one of (1) to (6) above, wherein a protective layer is provided on the reversible thermosensitive recording layer, and the protective layer contains an ultraviolet absorbing polymer. recoding media";
(8) The above (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 an ultraviolet absorbing ability. The reversible thermosensitive recording medium according to any one of (7);
(9) “Reversible thermosensitive recording medium according to any one of (1) to (8) above, wherein an information storage unit is provided”;
(10) In any one of the above (1) to (9), wherein an adhesive layer or a pressure-sensitive adhesive layer is provided on the surface opposite to the surface on which the reversible thermosensitive recording layer is provided. The reversible thermosensitive recording medium described;
(11) “Forming and / or erasing an image by heating the reversible thermosensitive recording layer using the reversible thermosensitive recording medium according to any one of (1) to (10). Characteristic image processing method ";
(12) “The image processing method according to (11), wherein an image is formed on the reversible thermosensitive recording layer using a thermal head”;
(13) “The image processing method according to (11), wherein the image is erased using a thermal head or a ceramic heater ”.

  The reversible thermosensitive recording medium of the present invention has a good color density and can provide a highly practical rewritable recording with excellent erasability at low temperature and low humidity.

The present invention is described in detail below.
The reversible thermosensitive recording medium of 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. 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. When the temperature of the recording medium initially in the decolored state (A) is raised, the leuco dye and the developer are melted and mixed at the temperature (T1) at which the recording medium starts to melt, and color development occurs 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 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, when the temperature is rapidly increased in the rapid cooling coloring state (C), decoloring occurs at a temperature (T2) lower than the coloring temperature (D to E), and when the temperature is lowered from here, the same decoloring 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 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 it is considered that the color former and the 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 the reversible thermosensitive recording medium of the present invention, the stability of the image density increases as the color structure has a more stable aggregate structure, and the crystallization of the developer occurs faster from the aggregate structure during color development in the decoloring process. It is considered that good erasability can be obtained. For this reason, as a color-decoloring / controlling agent, stabilization of the color-developing state and improvement of erasability have been studied by introducing a hydrogen-bonding associating group into a molecular structure having a long-chain alkyl. However, in such studies to increase the cohesive force, although the erasability is improved at about room temperature, the erasability is not improved in the low temperature and low humidity environment, and the erasability is sometimes deteriorated.

In the present invention, it has been found that low temperature and low humidity erasure is improved by having an amide group and an ether group having a long-chain alkyl in the molecular structure of the coloring / decoloring controlling agent.
Here, the ether group-containing amide compound used as a coloring / decoloring control agent in the present invention is represented by the following general formula (1).

（式中、ｌは０から３の整数を、ｍは３を、ｎは１２から１６の整数を示す。）
エーテル基含有アミド化合物の合成方法としては、エーテル基含有アルキルアミンと脂肪酸クロライドとの反応など、従来公知の方法によって合成することができる。
以下に、エーテル基含有アミド化合物の具体例を挙げるが本発明はこれらに限られるわけではない。

(In the formula, l represents an integer from 0 to 3 , m represents 3 , and n represents an integer from 12 to 16. )
The synthetic method of the error ether group-containing amide compounds, such as reaction with an ether group-containing alkyl amines and fatty acid chloride can be synthesized by a conventionally known method.
Hereinafter, specific examples are the invention of e ether group-containing amide compound is not limited thereto.

  The ether group-containing amide compound used in the present invention is preferably used in a proportion of 0.5 to 100% by weight with respect to the developer. When the amount is less than 0.5% by weight, a sufficient effect cannot be obtained. When the amount is more than 100% by weight, the color density is lowered, which is not preferable. More preferably, 1 to 30% by weight is particularly preferably used.

  As the leuco dye used in the reversible thermosensitive recording layer in the present invention, one or more compounds generally used in this type of reversible thermosensitive recording medium can be used. For example, phthalide compounds, azaphthalide compounds And known dye precursors such as fluorane compounds. Examples of these compounds are leuco dyes described in JP-A-5-124360, JP-A-6-210594, JP-A-10-230680 and the like. Of these, particularly preferred examples include 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-ethyl-p-) Toluidino) fluoran, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- ( - ethyl-2-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, and the like.

  Further, as the developer used in the reversible thermosensitive recording layer in the present invention, representative examples thereof include, for example, JP-A Nos. 5-124360, 6-220954, and No. 10-95175. Developer. The developer used here is a structure having a color developing ability for developing a leuco dye in the molecule, such as a phenolic hydroxyl group, a carboxylic acid group, or a phosphate group, and a structure that controls the cohesion between molecules, such as a long It is a compound having one or more structures in which chain hydrocarbon groups are linked. The linking moiety may be through a divalent or higher valent linking group containing a hetero atom, and the same linking group and / or aromatic group may be contained in the long-chain hydrocarbon group. Specific examples of such a reversible developer are disclosed in, for example, JP-A-9-290563, JP-A-11-188969, and JP-A-11-99749, in addition to the above-mentioned publications. Among these developers, particularly preferred examples include N- (4-hydroxyphenyl) -N′-octadecylurea, N- [11- (p-hydroxyphenoxy) undecano-N′-n-decanohydrazide. N- [3- (p-hydroxyphenyl) propiono] -N′-n-docosanohydrazide and the like are used.

  Specific examples of the crosslinked resin used for the reversible thermosensitive recording layer 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. Examples include resins having a group that reacts with a crosslinking agent such as butyrate, or resins obtained by copolymerizing a monomer having a group that reacts with a crosslinking agent and other monomers, but the present invention is limited to these compounds. is not.

  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. Further, 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 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 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.

  Furthermore, according to the present invention, together with the developer and leuco dye, the ether group-containing amide compound represented by the general formula (1) and a hydrogen bond such as a linear hydrocarbon group, an amide group or a urea group A conventional coloring / decoloring control agent having a group or the like can be used in combination in the reversible thermosensitive recording layer. By using the color-decoloring / controlling agent, the storage stability of the color-development image is good, and the decoloring property at the time of decoloring is also improved, so that good erasability can be obtained.

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 medium of the present invention is in the form of a label by providing an adhesive layer or a pressure-sensitive adhesive layer on the surface opposite to the surface on which the thermosensitive recording layer of the support constituting the reversible thermosensitive recording medium is formed. A reversible thermosensitive recording label can be obtained.
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 can be performed. Can be arbitrarily selected according to the purpose, and can be provided on the opposite surface of the support in the reversible thermosensitive recording medium, between the support and the thermosensitive recording layer, or in the thermosensitive recording. It can also be provided on a part of the 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 disk capable of rewriting storage information such as a flexible disk, MD, DVD-RAM and the like.
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 characterized in that an image is formed and / or erased by heating using the reversible thermosensitive recording medium, the member having the information storage unit or the label. FIG. 5 shows a schematic diagram of an example of the image processing method / apparatus of the present invention.

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.

Example 1
[Creation of thermal recording layer]
N- (4-hydroxyphenyl) -N′-octadecylurea 4 parts Ether group-containing amide compound represented by the following structural formula 0.2 part

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

Acrylic polyol resin (LR503 manufactured by Mitsubishi Rayon Co., Ltd.)
(Solid content 50% solution) 9 parts Methyl ethyl ketone 70 parts

The composition was pulverized and dispersed to a mean particle size of about 1 μm using a ball mill. To the obtained dispersion, 1.5 parts of 2-anilino-3-methyl-6-dibutylaminofluorane and 2 parts of Coronate HL (adduct type hexamethylene diisocyanate 75% ethyl acetate solution) manufactured by Nippon Polyurethane Co., Ltd. are added and stirred well. A thermal recording layer coating solution was prepared.
The thermal 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 produce a thermal recording with a film thickness of about 11.0 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 Nippon Polyurethane Co., Ltd., Coronate HX) 1.4 parts Silicon-based acrylic resin (GS-1015 manufactured by Toagosei Co., Ltd.) 0 .5 parts methyl ethyl ketone 10 parts or more of the composition was thoroughly 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 instead of the ether group-containing amide compound used in Example 1, an ether group-containing amide compound represented by the following structural formula was used.

Example 3
A reversible thermosensitive recording medium was prepared in the same manner as in Example 1 except that instead of the ether group-containing amide compound used in Example 1, an ether group-containing amide compound represented by the following structural formula was used.

Example 4
A reversible thermosensitive recording medium was prepared in the same manner as in Example 1 except that instead of the ether group-containing amide compound used in Example 1, an ether group-containing amide compound represented by the following structural formula was used.

Comparative Example 1
A reversible thermosensitive recording medium was prepared in the same manner as in Example 1 except that the ether group-containing amide compound used in Example 1 was not used.

Comparative Example 2
A reversible thermosensitive recording medium was prepared in the same manner as in Example 1 except that instead of the ether group-containing amide compound used in Example 1, a compound represented by the following structural formula was used.

The reversible thermosensitive recording medium produced as described above was tested as follows.
An image was printed under the conditions of a pulse width of 2.0 msec and a voltage of 16 V using a printing simulator manufactured by B. Com. Next, erasure was performed by changing the voltage in increments of 0.5 V from 7.0 V to 15.0 V on the obtained color image, and the density was measured in the same manner as the erasing density, and the erasure rate was calculated from the following formula. Was calculated. The above measurement was performed in an environment of 23 ° C. and 50% RH and 5 ° C. and 30% RH. The results are shown in Table 1.

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 stuck the reversible thermosensitive recording medium of the label form of this invention on the disk cartridge of MD. It is a figure which shows the example which stuck the reversible thermosensitive recording medium of the label form of this invention on CD-RW. It is a figure which shows the example which used the reversible thermosensitive recording medium of the label form 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 Conveying roller 47 Conveying roller 53 Thermal head

Claims (13)

Reversible that can form a relatively colored state and a decolored state on the support using an electron-donating color-forming compound and an electron-accepting compound, depending on the heating temperature and / or the cooling rate after heating. A reversible thermosensitive recording medium having a thermosensitive recording layer, wherein an ether group-containing amide compound represented by the following general formula (1) is used as a coloring / decoloring control agent.

(In the formula, l represents an integer from 0 to 3 , m represents 3 , and n represents an integer from 12 to 16. )
  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 reversible thermosensitive recording medium according to any one of claims 2 to 4, wherein the resin contained in the reversible thermosensitive recording layer is crosslinked with an isocyanate compound.   The reversible thermosensitive recording medium according to any one of claims 1 to 5, wherein a protective 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 claims 1 to 6, wherein a protective layer is provided on the reversible thermosensitive recording layer, and the protective layer contains an ultraviolet absorbing polymer.   8. 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 an ultraviolet absorbing ability. The reversible thermosensitive recording medium according to Item.   The reversible thermosensitive recording medium according to any one of claims 1 to 8, further comprising an information storage unit.   The reversible thermosensitive apparatus according to any one of claims 1 to 9, wherein an adhesive layer or a pressure-sensitive adhesive layer is provided on a surface of the support opposite to the surface provided with the reversible thermosensitive recording layer. recoding media.   An image processing comprising: forming and / or erasing an image by heating the reversible thermosensitive recording layer using the reversible thermosensitive recording medium according to any one of claims 1 to 10. Method.   The image processing method according to claim 11, wherein an image is formed on the reversible thermosensitive recording layer using a thermal head.   The image processing method according to claim 11, wherein the image is erased using a thermal head or a ceramic heater.

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