JP2006182694A - N-p-(1-HYDROXY-2,2,2-TRIFLUOROETHYL)PHENYL-N'-ALKYLSUCCINIC ACID AMIDE AND REVERSIBLE HEAT-SENSITIVE RECORDING MATERIAL - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reversible heat-sensitive recording material capable of forming a colored picture image on a white ground, by using a small-sized device, capable of conducting color development and color elimination by utilizing only a difference in heating conditions, having a high contrast, capable of especially being stabilized in a region in which a concentration thereof is low after the color elimination, and having high durability against repeated printing and elimination, and further high printing preservability under a high-temperature atmosphere. <P>SOLUTION: An N-p-(1-hydroxy-2,2,2-trifluoroethyl)phenyl-N'-alkylsuccinic acid amide is expressed by general formula (I) (n is an integer of not less than 11 and not more than 29). The reversible heat-sensitive recording material comprises the same. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a reversible thermosensitive recording material that can perform color development and decoloration by controlling heating conditions and can maintain the color development and decoloration states at room temperature. More specifically, the present invention forms a color image on a white background, has a high contrast, does not decrease the color density after repeated color development / decoloration, and is stable at a low density after decoloration. The present invention relates to a reversible thermosensitive recording material.

The thermal recording medium has the advantage that the recording device is compact and relatively inexpensive, the recording speed is fast, no consumables such as ink other than recording paper are required, and the recording method is a dry process, so maintenance is easy. Widely used as output paper for measuring instruments, registers, CD / ATM, facsimile, automatic ticket vending machines, handy terminals, etc. However, since the conventional thermal recording medium is irreversible recording, it is possible to additionally write information, but once recorded information cannot be erased and rewritten or reused.
Also, against the background of the dust problem and deforestation problem that has been actively discussed in recent years, it is desirable to recycle heat-sensitive recording paper. However, heat-sensitive recording paper is generally treated as a contraindication when recycling used paper. Therefore, it is difficult to recycle as paper.

  On the other hand, the thermosensitive recording material is also used as an information display material for magnetic recording cards such as prepaid cards and point cards. In these magnetic thermal cards, magnetic information is rewritten every time it is used, but thermal recording information cannot be rewritten. Therefore, updated information is added to a portion where no image is recorded. However, since the area of the heat-recordable portion is limited, the actual situation is that the amount of information to be thermally recorded is inevitably reduced or the card is reissued when the recording area is exhausted.

  As means for solving the above problems, a reversible thermosensitive recording material that can be rewritten any number of times has been developed. Furthermore, with the spread of IC cards in recent years, demands for visualization of information recorded on the cards have become stronger, and expectations for reversible thermosensitive recording media are increasing.

  Various reversible thermosensitive recording materials have been proposed against the background of these requirements. For example, a polymer-type reversible thermosensitive recording material using a change in transparency due to a difference in heating conditions is disclosed (see, for example, Patent Documents 1 to 3). However, this method has a drawback that visibility in a dark place is poor. In addition, there is also a drawback in that it is difficult to obtain a so-called paper-like recording medium that records a white color image on a white background and records a color image on a white background.

  As a method for solving these problems, there has been proposed a dye-type reversible thermosensitive recording medium capable of reversible recording while using a dye used in a conventional thermosensitive recording medium. The dye-type reversible thermosensitive recording material can record a color image on a white background, and has a relatively high contrast because it is a recording system that utilizes changes in absorption wavelength depending on heating conditions. As a dye-type reversible thermosensitive recording material, for example, the following methods are known.

  Although a method using an ascorbic acid derivative as a developer (see, for example, Patent Document 4) has been disclosed, it has a disadvantage that it is not sufficiently decolored. In addition, a method of reversibly controlling color development and decoloration using an amphoteric compound having both an acidic group and a basic group in the molecule as a developer (see, for example, Patent Document 5), an acidic substance and a basic substance Are mixed and used as a color development / decoloration control agent (see, for example, Patent Document 6). The contrast of the decolored state is not clear and the visibility is poor.

  A method has been proposed in which a compound having both an electron-accepting structure and a linear aliphatic group in the molecule is used as a developer, and the property that the linear aliphatic group aggregates for decoloring is proposed. For example, although a method using an organic phosphate structure as an electron-accepting structure (see, for example, Patent Document 7) is disclosed, it has a drawback that the decoloring property is insufficient. On the other hand, the method using a carboxyl group as the electron-accepting structure (see, for example, Patent Document 8) has a drawback that the color developability is insufficient.

  In a method using a phenolic compound having a linear aliphatic group as a developer (see, for example, Patent Document 9), a reversible thermosensitive recording medium having a relatively good balance between color development and decoloring properties can be obtained. However, the decoloring property is still insufficient, and a decoloring aid is necessary to obtain a practical level of decoloring property (see, for example, Patent Documents 10 and 11). However, when a decoloring aid is added, there arises a problem that the storability of printing is lowered.

Therefore, in the reversible thermosensitive recording material using these materials, the information remaining after the erasing operation and the newly printed information overlap with each other, the visibility deteriorates, or the storage stability is insufficient. If stored below, the density of the printed part will decrease and the visibility will decrease. For example, when it is applied to a point card, the card issuer will limit the number of repeated printing and erasing, In fact, it is necessary to take measures such as setting an expiration date, and improvements are desired.
In order to solve these problems, the present inventors have previously proposed a color developer having excellent color developability and decoloring property and high storage stability (see, for example, Patent Document 12). At present, there is room for improvement in terms of stability against repeated printing and erasing.

  Further, in the temperature indicating field, a reversible thermochromic composition using a specific fluoroalcohol compound as a color developing substance has already been proposed (see, for example, Patent Document 13). This composition is capable of reversible color development and decoloration by combining a compound having a linear aliphatic group with a dye and a color developing substance. However, the colored state appears only when heated, and the colored state cannot be maintained when not heated, which is different from the technical field of the present invention. In addition, compounds having both a fluoroalcohol group and a linear aliphatic group and / or a hydrogen bonding group in the same molecule as in the present invention are not shown.

JP 2000-141916 A JP 2001-191651 A JP 2002-187366 A Japanese Patent Laid-Open No. 63-173684 Japanese Patent Laid-Open No. 8-150783 JP-A-10-329420 Japanese Patent Laid-Open No. 7-40659 JP 2000-247034 A Japanese Patent Laid-Open No. 6-210954 JP 2001-113831 A JP 2002-248860 A JP 2001-205944 A Japanese Patent Laid-Open No. 11-92759 (see page 2)

  An object of the present invention is to provide a reversible thermosensitive recording medium having a high contrast, which can form a color image on a white background using a small apparatus and can perform color development and decoloration only by a difference in heating conditions. It is. In particular, it is stable at a low density after erasing, and has high durability against repeated printing and erasing and high printing storability (hereinafter referred to as heat-resistant storability) in a high temperature atmosphere.

  In order to obtain a reversible thermosensitive recording material capable of color development and decoloring only by heating and having a high contrast between the color developing part and the color erasing part, the present inventors can obtain a reversible thermosensitive recording material. As a result of diligent research focusing on a dye-type reversible thermosensitive recording system composed mainly of a light-colored dye precursor and a developer, a novel Np- (1-hydroxy-) useful as a developer. 2,2,2-trifluoroethyl) phenyl-N′-alkyl succinamide was found and the present invention was completed.

The present invention includes the following inventions.
(1) The following general formula (I):

（ただし上式において、ｎは１１以上２９以下の整数を表す。）
で表されるＮ−ｐ−（１−ヒドロキシ−２，２，２−トリフルオロエチル）フェニル−Ｎ’−アルキルコハク酸アミド。

(In the above formula, n represents an integer of 11 to 29.)
Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl-N′-alkylsuccinic acid amide represented by the formula:

  (2) The following chemical formula (II):

で表されるＮ−ｐ−（１−ヒドロキシ−２，２，２−トリフルオロエチル）フェニル−Ｎ’−ドコシルコハク酸アミド。

Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl-N′-docosylsuccinic acid amide represented by the formula:

  (3) A sheet-like support, a colorless or light-colored dye precursor formed on the sheet-like support, and a heat-sensitive recording layer containing a color developer that reversibly develops and decolors the dye precursor. In the reversible thermosensitive recording material, the developer includes the Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl-N′-alkylsuccinamide described in the item (1). A reversible thermosensitive recording material.

  The reversible thermosensitive recording material of the present invention forms a color image on a white background and has a high contrast. In particular, the coloring density after repeated coloring and erasing does not decrease, and is stable at a low density after erasing. Moreover, it is excellent also in heat resistant storage stability. Therefore, the reversible thermosensitive recording material of the present invention has extremely high practical value.

The novel compound of the present invention is Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl-N′-alkylsuccinamide represented by the above general formula (I).
The compound of the present invention can be synthesized by, for example, the following five-step reaction, but the synthesis method is not limited to the following reaction.

  The solvent used in the reaction formulas (III) to (VII) is not particularly limited as long as it does not react with the reaction reagent and the catalyst and does not deactivate.

  In the trifluoromethylation reaction represented by the above reaction formula (III), preferred combinations of the solvent and the catalyst (C) include dimethylformamide and triethylamine, tetrahydrofuran and tetrabutylammonium fluoride, and the like.

  The reduction reaction represented by the above reaction (IV) is preferably a catalytic reduction method. In this case, the preferred catalyst (E) is palladium-activated carbon. Further, preferred solvents include tetrahydrofuran, ethyl acetate, methanol and the like.

  In the amidation reaction represented by the above reaction (V), triethylamine and pyridine are preferably used for the base (G). Moreover, toluene and tetrahydrofuran are mentioned as a preferable solvent.

  In the hydrolysis reaction shown in the above reaction (VI), potassium hydroxide and sodium hydroxide are preferably used for the base (I). A preferable solvent is a mixed solvent of tetrahydrofuran and water.

  In the dehydration condensation reaction shown in the above reaction (VII), it is preferable to use 1-hydroxybenzotriazole and N, N′-diisopropylcarbodiimide in combination as a dehydration condensation agent. Moreover, tetrahydrofuran is mentioned as a preferable solvent.

In a preferred embodiment of the present invention, the reversible thermosensitive recording material is a sheet-like support, a colorless or light dye precursor formed on the sheet-like support, and reversibly developing and decoloring the same. And Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl- represented by the general formula (I) as the developer. N'-alkyl succinic acid amide is included.
In the general formula (I), when n is 10 or less, sufficient decoloring property cannot be obtained. On the other hand, when n is 30 or more, decoloring property is saturated and the molecular weight increases, so The density decreases and a sufficient color density cannot be obtained.

  In the reversible thermosensitive recording material of the present invention, the thermosensitive recording layer containing a color developing component mainly composed of a leuco dye and a developer is rapidly colored after being heated above the temperature at which the color developing component melts, and then rapidly cooled. This colored state is maintained even at room temperature. On the other hand, the color-developing portion held at room temperature is heated to a temperature at which the color-forming complex, which is a solid solution of the color-forming component, melts, and then slowly cooled or heated to a temperature at which the color-forming complex is melted or lower. It can be erased, and its decolored state is maintained even after cooling to room temperature.

  The mechanism of color development and decoloration is not clear, but the alcoholic hydroxyl group in the developer molecule is activated by the alkyl group with a large electronegativity and bonded with a fluorine atom, which makes it a basic leuco dye. On the other hand, color development occurs with a strong color developing ability. On the other hand, during the erasing operation, the cohesion of linear aliphatic groups or hydrogen bonding groups in the developer molecules induces crystallization of the developer. The dye and the developer are considered to be separated and decolored. The temperature required to melt the color forming component depends on the melting point of the developer or the like, but is generally 120 to 240 ° C. In general, color development is performed by a thermal head or the like, which is easy to heat in units of several milliseconds and rapidly cool accordingly. In general, the color erasing is performed by heating at a temperature higher than the temperature at which the color developing component melts and then slowly cooling, or heating at a temperature of 60 to 180 ° C. and below the temperature at which the color developing component melts for several tens of milliseconds or more. Is done. For decoloring, a heat stamp or a heat bar that can be easily heated and gradually cooled is used.

  As preferred specific examples of Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl-N′-alkylsuccinamide represented by the above general formula (I), the following compounds No. Although (1)-(5) are shown, it is not limited to these. These compounds may be used alone or in combination of two or more thereof.

  Further, as the developer of the present invention, Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl-N′-dodecylsuccinic acid amide represented by the above chemical formula (II) (Compound No. .5) is most preferably used and exhibits good color developability, color erasability and heat-resistant storage stability.

  Examples of the compound used as the dye precursor in the heat-sensitive recording layer of the reversible thermosensitive recording material of the present invention include triphenylmethane-based compounds, fluorane-based compounds, diphenylmethane-based compounds, and the like, which can be selected from conventionally known compounds. .

  These dye precursors are, for example, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3,3-bis (P-methylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino-7-dibenzylaminobenzo [α] fluorane, 3- (1-ethyl-2-methylindol-3-yl) -3- ( 4-diethylamino-2-n-hexyloxyphenyl-4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-diethylamino-2-methylphenyl-4-azaphthalide, 3 -(4-Diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide, 3- (2-methyl-1-n-octylindole) -3-yl) -3- (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide, 3- (N-ethyl-N-isopentylamino) -6-methyl-7-anilinofluorane, 3- Diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (o, p-dimethylanilino) fluorane, 3- (N-ethyl-Np-toluidino) -6 Methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3- (N-cyclohexyl-N-methyl) Amino) -6-methyl-7-anilinofluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-diethylamino-7- (m-trifluoromethyl) Anilino) fluorane, 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane, 3- [N- (3-ethoxypropyl) -N-ethylamino] -6-methyl-7-ani Linofluorane, 3- (Nn-hexyl-N-ethylamino) -7- (o-chloroanilino) fluorane, 3- (N-ethyl-N-2-tetrahydrofurfurylamino) -6-methyl-7 -Anilinofluorane, 2,2-bis {4- [6 '-(N-cyclohexyl-N-methylamino) -3'-methylspiro [phthalide-3,9'-xanthene] -2'-ylamino] phenyl } Propane and 3-dibutylamino-7- (o-chloroanilino) fluorane.

  3,6-dimethoxyfluorane, 3-pyrrolidino-6-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7,8 -Benzofluorane, 3-diethylamino-6,7-dimethylfluorane, 3- (N-methyl-p-toluidino) -7-methylfluorane, 3- (N-methyl-N-isoamylamino) -7, 8-benzofluorane, 3,3′-bis (1-n-amyl-2-methylindol-3-yl) phthalide, 3- (N-methyl-N-isoamylamino) -7-phenoxyfluorane, 3 , 3′-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 3,3′-bis (1-ethyl-2-methylindol-3-yl) fur Lido, 3,3′-bis (p-dimethylaminophenyl) phthalide, 3- (N-ethyl-Np-tolylamino) -7- (N-phenyl-N-methylamino) fluorane, 3-diethylamino-7 -Anilinofluorane, 3-diethylamino-7-benzylaminofluorane, 3-pyrrolidino-7-dibenzylaminofluorane and the like can be selected, but the present invention is not limited thereto, Two or more types may be used in combination.

  The reversible thermosensitive recording material of the present invention can contain a conventionally known thermofusible substance generally known as a sensitizer in the thermosensitive recording layer. Representative examples thereof include m-terphenyl, 1-hydroxy-2-naphthoic acid phenyl ester, p-benzyloxybenzoic acid benzyl, benzyl naphthyl ether, dibenzyl terephthalate, diphenyl carbonate, ditolyl carbonate, diphenyl sulfone, 1,2-bis (m-tolyloxy) ethane, p-benzylbiphenyl, 1,5-bis (p-methoxyphenoxy) -3-oxapentane, oxalic acid diesters, di (4-methylbenzyl) oxalate, 1 , 4-bis (p-tolyloxy) benzene, 1,4-bis [2- (4-methylbenzyloxy) ethoxy] benzene, and the like. These compounds are reversible thermosensitive by relatively low applied energy. It has the ability to enable high density color development of the recording medium.

The reversible thermosensitive recording material of the present invention can contain a heat-fusible substance having a long-chain alkyl group generally known as a decoloring accelerator in the thermosensitive recording layer as long as the desired effect is not inhibited. Examples of such decoloring accelerators include hexadecanamide, octadecyl urea, dioctadecyl urea, docosanoyl hydrazide, N, N′-didocosyl oxadiamide, and the like.
These compounds improve the reversibility by promoting the decolorization reaction even at relatively low temperatures during image erasing operations, in addition to the ability to enable high density color development of reversible thermosensitive recording media with relatively low applied energy. Has the ability to

  In addition, the heat-sensitive recording layer according to the present invention may contain waxes and pigments in a range that does not impair the effects of the present invention, and further contains a binder in order to fix these components to the support. .

  As the wax, for example, known ones such as paraffin, amide wax, bisimide wax, metal salt of higher fatty acid can be used. However, if a higher fatty acid metal salt is added, the color disappearance increases with repeated color development / decoloration, and the erasure of the color image may be incomplete. It is preferably 1% by mass or less of the dry mass of the recording layer.

  Examples of the pigment include silica, clay, calcined clay, talc, calcium carbonate, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, and surface-treated inorganic fine powders such as calcium carbonate and silica. And organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin. However, the addition of zinc oxide increases the decoloring density as repeated color development / decoloration occurs, and there is a risk that erasure of the color image will be incomplete, so the content of zinc oxide is the dry mass of the thermal recording layer. It is preferable that it is 1 mass% or less.

  The binder can be selected from water-soluble polymers, water-dispersible polymers, water-insoluble polymers, active energy ray-curable compounds, and the like.

  Examples of water-soluble polymers and water-dispersible polymers include polyvinyl alcohols of various molecular weights and derivatives thereof (for example, acetoacetyl group-modified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, sulfonyl group-modified polyvinyl alcohol, etc.), starch And derivatives thereof (eg, oxidized starch, vinyl acetate graft starch, aldehyde-modified starch, etc.), cellulose derivatives (methoxycellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, etc.), polyacrylic acid soda, polyvinylpyrrolidone, acrylic acid amide / acrylic acid ester Polymer, acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate Water-soluble polymer materials such as gelatin, gelatin, and casein, and polyvinyl acetate, polyurethane, styrene / butadiene copolymers, polyacrylic acid, polyacrylate esters, vinyl chloride / vinyl acetate copolymers, polybutyl methacrylate Latex such as ethylene / vinyl acetate copolymer and styrene / butadiene / acrylic copolymer can be used. These polymers may be used alone or in combination of two or more thereof, and are not limited to the examples listed here.

Examples of water-insoluble polymers include phenoxy resin, cellulose acetate butyrate resin, polyurethane resin, polyester resin, (meth) acrylic resin, styrene / (meth) acrylic copolymer, vinyl chloride / vinyl acetate copolymer Polycarbonate resins and the like, and these are usually used after being dissolved in a suitable organic solvent. These resins may be used alone or in combination of two or more thereof, and are not limited to the examples listed here.
In addition, by using resins that have been modified to have hydroxyl groups in these polymers, and further adding a compound having a plurality of isocyanate groups in the molecule as a cross-linking agent to cure the resin, a reversible feeling with excellent durability is achieved. A thermal recording material is obtained. The addition amount of the crosslinking agent is appropriately determined depending on the amount of hydroxyl groups in the resin and the number of isocyanate groups in the crosslinking agent to be used.

  Examples of the compound used as the crosslinking agent include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1,5-naphthalene. Diisocyanate, p-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, 4,4′-biphenylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, Methylene bis (4-cyclohexyl isocyanate), hydrogenated diphenylmethane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, bis (2-isocyana) Ethyl) fumarate, 6-isopropyl-1,3-phenyl diisocyanate, lysine diisocyanate, triphenylmethane triisocyanate, etc. polymethylene polyphenyl isocyanate. These crosslinking agents may be used alone or in admixture of two or more thereof, and are not limited to the examples listed here.

Examples of the active energy ray-curable compounds can be selected from the following compounds, but these may be used alone or in combination of two or more thereof, and are limited to the examples listed here. It is not a thing.
(1) Aliphatic, alicyclic, and aromatic alcohol and polyalkylene glycol acrylate (or methacrylate) compounds. (2) Aliphatic, alicyclic and aromatic acrylate (or methacrylate) compounds obtained by adding an alkylene oxide to an alcohol. (3) Polyacryloyl (or methacryloyl) alkyl phosphate esters. (4) A reaction product of a polybasic acid, a polyol, and acrylic (or methacrylic) acid. (5) Reaction product of isocyanate, polyol, and acrylic (or methacrylic) acid. (6) A reaction product of an epoxy compound and acrylic (or methacrylic) acid. (7) A reaction product of an epoxy compound, a polyol, and acrylic (or methacrylic) acid. (8) Amides composed of aliphatic, alicyclic, and aromatic amines, or nitrogen-containing cyclic compounds and acrylic acid (or methacrylic acid).

When the active energy ray-curable compounds are cured by ultraviolet irradiation, an appropriate amount of a photoinitiator is added, and an ultraviolet irradiation device having a high-pressure mercury lamp, a xenon lamp, or a metal halide lamp is used as an irradiation light source. Is determined as necessary.
Examples of photoinitiators include acetophenone, benzophenone, benzoin ether, chloroacetophenone, diethoxyacetophenone, hydroxyacetophenone, α-aminoacetophenone, benzyl methyl ketal, thioxanthone, α-acyl oxime ester, acyl phosphine oxide, glyoxy ester, Examples include, but are not limited to, 3-ketocoumarin, 2-ethylanthraquinone, camphorquinone, benzyl, Michler's ketone, and the like.

  In addition, when the active energy ray-curable compounds are cured by electron beam irradiation, the electron beam accelerator to be used is not particularly limited, and for example, a bandegraft scanning method, a double scanning method, a curtain beam, etc. Although an electron beam irradiation apparatus such as a system can be used, a curtain beam system that is relatively inexpensive and can provide a large output is effectively used. The acceleration voltage during electron beam irradiation is preferably 100 to 300 kV, and the absorbed dose is preferably 0.1 to 9 Mrad. The oxygen concentration in the atmosphere during electron beam irradiation is preferably 500 ppm or less. If the oxygen concentration exceeds 500 ppm, oxygen may act as a retarder for the polymerization reaction, and the electron beam curable resin may be insufficiently cured.

  In the thermosensitive recording layer of the reversible thermosensitive recording material according to the present invention, the content of the dye precursor is generally preferably 5 to 40% by mass of the dry mass of the thermosensitive recording layer, and the content of the developer is In general, it is preferably 5 to 50% by mass of the dry mass of the thermosensitive recording layer. If the developer content is less than 5% by mass, the developing ability is insufficient. On the other hand, if the content exceeds 50% by mass, the developer ability is saturated, and the contrast between the color density and the decoloring density. However, there is no particular improvement and it may be economically disadvantageous.

  When waxes and pigments are contained in the heat-sensitive recording layer, the content is preferably 2 to 20% by mass and 5 to 50% by mass, respectively, and the content of the binder is generally 5 to 70%.

The support used for the reversible thermosensitive recording material of the present invention includes paper (including acidic paper and neutral paper) that has been used for conventional thermosensitive recording media, and coated paper coated with a pigment, latex, etc. on the surface, In addition to laminated paper, synthetic paper made from polyolefin resin, plastic film such as polyolefin, polyester, polyimide, etc., glass plate, conductive rubber sheet, etc. can be selected. On at least one surface of such a support, a coating solution containing the above-mentioned mixture of required components is applied and dried to produce a reversible thermosensitive recording material. The coating amount is preferably from 1 to 15 g / ^{m 2} in a state where the coating liquid layer has dried, 2 to 10 g / ^{m 2} is particularly preferred.

  In the present invention, an undercoat layer can be provided under the reversible thermosensitive coloring layer. Further, the back surface of the reversible thermosensitive recording medium can be provided with a back layer for preventing blocking at the time of contact between the surfaces, suppressing water and oil penetration from the back surface, and controlling curl. Furthermore, in order to improve heat resistance, light resistance, printability, wear resistance, and durability of repeated coloring and decoloring, a coating layer such as a protective layer and a printing layer on the reversible thermosensitive coloring layer. Can also be formed. Further, by using a hardened layer containing an active energy ray-curable compound as a main component for the protective layer, it is possible to drastically improve the abrasion resistance, coloring, and decoloring repeated durability.

In the present invention, an intermediate layer comprising at least one of a water-soluble polymer, a water-dispersible polymer, a thermosetting resin, and an active energy ray-curable compound as a binder between the heat-sensitive recording layer and the coating layer. It is preferable to have at least one layer.
Moreover, light resistance can be improved by making this intermediate | middle layer contain ultraviolet-absorbing inorganic pigments, such as a titanium oxide, and an organic ultraviolet absorber.

  In the present invention, in order to increase the added value of the reversible thermosensitive recording material, it can be further processed to provide a reversible thermosensitive recording material having a higher function. For example, reversible thermosensitive recording that can be magnetically recorded by applying pressure sensitive adhesive, rehumidified adhesive, delayed tack type adhesive on the back surface to give adhesive paper, rehumidified adhesive paper, delayed tack paper, or magnetic processing. It can be set as a recording body. In addition, a recording paper capable of recording on both sides can be provided by using the back surface to provide a function as a thermal transfer paper, inkjet paper, carbonless paper, electrostatic recording paper, and xerographic paper. Of course, a double-sided reversible thermosensitive recording material can also be used.

  The device for recording (coloring) and erasing (decoloring) the image can be selected from a thermal head, a thermostatic bath, a heating roller, a thermal pen, a planar heating element, a laser beam, an infrared ray, etc., depending on the purpose of use. In particular, it is not limited to these.

  Hereinafter, the present invention will be specifically described with reference to examples. Unless otherwise specified, “parts” and “%” represent “parts by mass” and “% by mass”, respectively. The developer used in the examples was synthesized as follows.

  In the following synthesis examples, unless otherwise stated, all reaction vessels were flasks equipped with reflux condensers, all organic solvents were subjected to dehydration operations such as distillation, and water was distilled water. . Unless otherwise specified, the synthesis was performed under an inert gas stream.

(Synthesis Example 1)
Synthesis method of Np- (1-hydroxy-2,2,2-trifluoroethyl) succinic monoamide (common intermediate):
4-Nitrobenzaldehyde (15.1 g) and triethylamine (2.0 g) are dissolved in dimethylformamide (100 mL), and trifluoromethyltrimethylsilane (14.2 g) is added dropwise. After stirring at room temperature for 17 hours, 3N hydrochloric acid (10 mL) is added, and the mixture is stirred at room temperature for 30 minutes. Water (200 mL) is further added, followed by extraction three times with ethyl acetate (150 mL) (using a total of 450 mL). The organic layer is collected, dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure until the volume is about 100 mL. To this solution, palladium on activated carbon (5.0 g) is stirred for 3 hours under pressure of 200 kPa of hydrogen gas in a pressure reactor. After filtering the reaction solution, the solution is concentrated under reduced pressure until the filtrate becomes about 50 mL, and n-hexane (100 mL) is added to the residue while stirring to precipitate crystals. The precipitated crystals are collected by filtration and dried under reduced pressure to give 1- (p-aminophenyl) -2,2,2-trifluoroethanol as a colorless powder (14.3 g). (The yield based on 4-nitrobenzaldehyde is 75%)

  The 1- (p-aminophenyl) -2,2,2-trifluoroethanol (9.56 g) was dissolved in tetrahydrofuran (100 mL), pyridine (7.91 g) was further added, and the solution was cooled with ice. Ethyl succinic chloride (8.23 g) is added dropwise. After completion of the dropwise addition, the reaction solution is returned to room temperature and stirred for 17 hours, 4N aqueous potassium hydroxide solution (30 mL) is added, and the mixture is stirred for 4 hours. 3N hydrochloric acid (60 mL) is added to the reaction mixture, and the organic matter is extracted with ethyl acetate (300 mL). The organic layer is collected, dried over anhydrous magnesium sulfate, filtered, and the filtrate is concentrated under reduced pressure. Hexane is added to the residue, and the precipitated crystals are collected by filtration and dried under reduced pressure to give N- {p- (1-hydroxy-2,2,2-trifluoroethyl) phenyl} succinic acid monoamide as a common intermediate. Obtained as a colorless powder (14.1 g). (Yield based on 1- (p-aminophenyl) -2,2,2-trifluoroethanol is 97%)

The analytical values of this crystal are as follows.
Melting point: 122.2 ° C
Results of NMR measurement (in methyl sulfoxide-d6) (numbers are in ppm);
δ2.54 (m, 4H), 5.05 (bs, 1H), 6.72 (d, 1H), 7.38 (d, 2H), 7.59 (d, 2H), 10.34 (s , 1H), 12.13 (bs, 1H)
Results of IR measurement (KBr tablet method) (numbers are cm-1); 688, 823, 1088, 1114, 1166, 1221, 1247, 1309, 1406, 1538, 1602, 1655, 1731, 3379

Synthesis method of Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl-N′-docosylsuccinic acid amide (Compound No. 5):
Np- (1-hydroxy-2,2,2-trifluoroethyl) succinic acid monoamide (11.7 g) and docosylamine (13.0 g), which are the common intermediates synthesized by the above method, were added to tetrahydrofuran (13.0 g). 400 mL), add 1-hydroxybenzotriazole (6.1 g) and stir at room temperature for 30 minutes. N, N′-diisopropylcarbodiimide (5.0 g) is added to the reaction mixture, and the mixture is stirred at room temperature for 30 minutes and further at 70 ° C. for 4 hours. After returning the reaction solution to room temperature, it was poured into water (500 mL), and the precipitated solid was collected by filtration, washed with water, and dried under reduced pressure to give Np- (1-hydroxy-2,2,2-trifluoroethyl). Phenyl-N′-docosylsuccinamide is obtained as a colorless solid (22.0 g). (Yield 92% based on Np- (1-hydroxy-2,2,2-trifluoroethyl) succinic monoamide)

The analytical values of this crystal are as follows.
Melting point: 144.3 ° C
Results of NMR measurement (in tetrahydrofuran-d8) (numbers are in ppm);
δ 0.88 (t, 3H), 1.28 (s, 38H), 1.44 (m, 2H), 2.43 (t, 2H), 2.56 (t, 2H), 3.13 (q , 2H), 4.92 (t, 1H), 5.69 (d, 1H), 7.06 (bs, 1H), 7.35 (d, 2H), 7.61 (d, 2H), 9 .38 (s, 1H), 10.82 (s, 1H)
Results of IR measurement (KBr tablet method) (the number is cm-1); 718, 1076, 1127, 1183, 1262, 1334, 1414, 1470, 1535, 1660, 2917, 3313

(Synthesis Example 2)
Synthesis method of Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl-N′-octadecylsuccinic acid amide (Compound No. 3):
Np- (1-hydroxy-2,2,2-trifluoroethyl) succinic acid monoamide (11.7 g) and octadecylamine (10.7 g), which are the common intermediates synthesized by the above method, were added to tetrahydrofuran. (400 mL), add 1-hydroxybenzotriazole (6.1 g) and stir at room temperature for 30 minutes. N, N′-diisopropylcarbodiimide (5.0 g) is added to the reaction mixture, and the mixture is stirred at room temperature for 30 minutes and further at 70 ° C. for 4 hours. After returning the reaction solution to room temperature, it was poured into water (500 mL), and the precipitated solid was collected by filtration, washed with water, and dried under reduced pressure to give Np- (1-hydroxy-2,2,2-trifluoroethyl). Phenyl-N′-octadecylsuccinamide is obtained as a colorless solid (20.2 g). (Yield 93% based on Np- (1-hydroxy-2,2,2-trifluoroethyl) succinic monoamide)

The analytical values of this crystal are as follows.
Melting point: 143.1 ° C
Results of NMR measurement (in tetrahydrofuran-d8) (numbers are in ppm);
δ 0.89 (t, 3H), 1.28 (s, 30H), 1.44 (m, 2H), 2.44 (t, 2H), 2.56 (t, 2H), 3.13 (q , 2H), 4.92 (t, 1H), 5.69 (d, 1H), 7.07 (bs, 1H), 7.35 (d, 2H), 7.61 (d, 2H), 9 .38 (s, 1H), 10.83 (s, 1H)
Results of IR measurement (KBr tablet method) (numbers are cm-1): 719, 1080, 1125, 1177, 1261, 1340, 1414, 1469, 1542, 1660, 2909, 3310
Example 1

A reversible thermosensitive recording material was prepared by the following operations (1) to (5).
(1) Preparation of dispersion A
Ingredients section
3-Dibutylamino-6-methyl-7-
Anilinofluorane 20
Polyvinyl alcohol 10% aqueous solution 10
Water 70
The composition was pulverized using a sand grinder until the average particle size became 1.1 μm.

(2) Preparation of dispersion B
Ingredients section
Np- (1-hydroxy-2,2,2-trif
Luoethyl) phenyl-N'-docosylcoha
Succinamide (Compound No. 5, described in Synthesis Example 1)
20)
Polyvinyl alcohol 10% aqueous solution 10
Water 70
The composition was pulverized using a sand grinder until the average particle size became 1.1 μm.

(3) Formation of reversible thermosensitive recording layer 100 parts of the above A liquid, 250 parts of B liquid, and 250 parts of 10% polyvinyl alcohol aqueous solution were mixed and stirred to obtain a coating liquid. This coating solution was applied to one side of a 150 μm thick PET film so that the coating amount after drying was 5.0 g / m ² and dried to form a reversible thermosensitive recording layer.

(4) Formation of intermediate layer 60 parts of a 50% dispersion of kaolinite clay and 200 parts of a 10% polyvinyl alcohol aqueous solution were mixed and stirred to prepare an intermediate layer coating solution. This coating solution was applied onto the reversible thermosensitive recording layer (3) so that the coating amount after drying was 1.5 g / m ² and dried to form an intermediate layer.

(5) Formation of overcoat layer 40 parts of polyester acrylate (trade name: Aronix M-8030, manufactured by Toa Gosei Co., Ltd.), 40 parts of polyester acrylate (trade name: Aronix M-6200, manufactured by Toa Gosei Co., Ltd.), calcium carbonate (product) 20 parts) (name: Ryton A, manufactured by Bihoku Powder Chemical Co., Ltd.) were mixed and stirred, and coated on the intermediate layer (4) so that the coating amount was 2.5 g / m ² . The resulting coating layer was irradiated with an electron beam under the conditions of an oxygen concentration of 300 ppm or less in the electron beam irradiation chamber, an acceleration voltage of 175 kV, and an absorbed dose of 3 Mrad to form an overcoat layer, whereby a reversible thermosensitive recording material was obtained. .

(6) Color developability and decolorability test The reversible thermosensitive recording material thus obtained was subjected to a printing voltage of 21.7 V and a printing pulse of 1.0 ms using a thermal coloring tester THPMD manufactured by Okura Electric. Printed. This print color density was measured with a Macbeth reflection densitometer RD-914.
Further, this colored sample was heated using a thermal inclination tester manufactured by Toyo Seiki under the conditions of a heating temperature of 100 ° C., a pressure of 1 kg / cm ² , and a heating time of 1.0 second, and then the decoloring density was measured with a Macbeth reflection densitometer. Measured with RD-914. The test results are shown in Table 1.

(7) Repeated color development / decolorability test The color development density and decoloration density after repeating the color development and decolorability tests described in (6) above 20 times were measured with a Macbeth reflection densitometer RD-914. The test results are shown in Table 1.

(8) Heat-resistant storage stability test The color density of the above-mentioned item (6) was measured with a Macbeth reflection densitometer RD-914 after being stored for 24 hours in an environment of 60 ° C., and the residual rate of printing (%) Was calculated. The test results are shown in Table 1.
Example 2

A reversible thermosensitive recording material was prepared and tested in the same manner as in Example 1. However, in preparing the dispersion B, Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl-N′-docosylsuccinic acid amide (Compound No. 5) was used instead of Np- (1-Hydroxy-2,2,2-trifluoroethyl) phenyl-N′-octadecyl succinic acid amide (Compound No. 3, compound of general formula (I) where n is 17; synthesized by the method described in Synthesis Example 2 ) Was used. The test results are shown in Table 1.
Example 3

A reversible thermosensitive recording material was prepared and tested in the same manner as in Example 1. However, in preparing the dispersion B, Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl-N′-docosylsuccinic acid amide (Compound No. 5) was used instead of Np- (1-Hydroxy-2,2,2-trifluoroethyl) phenyl-N′-dodecylsuccinic acid amide (compound No. 1, a compound in which n in formula (I) is 11) was used. The test results are shown in Table 1.
Comparative Example 1

A reversible thermosensitive recording material was prepared and tested in the same manner as in Example 1. However, in preparing the dispersion B, instead of Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl-N′-docosylsuccinic acid amide (Compound No. 5), 1- (p -Stearoylamino) phenylethanol (having a methyl group instead of the trifluoromethyl group of compound No. 5) was used. The test results are shown in Table 1.
Comparative Example 2

A reversible thermosensitive recording material was prepared and tested in the same manner as in Example 1. However, in preparing the dispersion B, Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl-N′-docosylsuccinic acid amide (Compound No. 5) was used instead of Np- (1-Hydroxy-2,2,2-trifluoroethyl) phenyl-N′-octylsuccinic acid amide (compound having no straight chain aliphatic group having 11 to 30 carbon atoms) was used. The test results are shown in Table 1.
Comparative Example 3

A reversible thermosensitive recording material was prepared and tested in the same manner as in Example 1. However, in the preparation of Dispersion B, p-stearoylamino was used instead of Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl-N′-docosylsuccinic acid amide (Compound No. 5). Phenol (a compound having a phenolic hydroxyl group and a linear aliphatic group) was used. The test results are shown in Table 1.
Comparative Example 4

  A reversible thermosensitive recording material was prepared and tested in the same manner as in Example 1. However, in preparing the dispersion B, 3-fluoropropanol was used instead of Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl-N′-docosylsuccinic acid amide (Compound No. 5). A mixture (reversible thermochromic material) of 4 parts and neopentyl stearate 16 parts was used. The test results are shown in Table 1.

As is clear from comparison between Examples 1 to 3 and Comparative Example 1, the alcoholic hydroxyl group activated by the fluorocarbon group exhibits a strong color developing ability with respect to a basic leuco dye. As is apparent from the comparison between -3 and Comparative Example 2, the developer of the present invention has a linear aliphatic group having 12 to 30 carbon atoms in the molecule, so that reversible coloring and decoloring can be achieved. It is possible.
Further, as apparent from the comparison between Examples 1 to 3 and Comparative Example 3, the image formed on the reversible thermosensitive recording material of the present invention has a phenolic compound having a linear aliphatic group chain as a developer. It has a higher contrast than the color image obtained by use, and is excellent in repeatability of coloring and decoloring. Moreover, it is excellent also in heat resistant storage stability.
Furthermore, the reversible thermochromic material used in Comparative Example 4 cannot maintain the colored state after the printing operation as shown in Examples 1 to 3.

The reversible thermosensitive recording material of the present invention forms a color image on a white background and has a high contrast. In particular, the coloring density after repeated coloring and erasing does not decrease, and is stable at a low density after erasing. Therefore, the reversible thermosensitive recording material of the present invention has extremely high practical value.

Claims (3)

The following general formula (I):

(In the above formula, n represents an integer of 11 to 29.)
Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl-N′-alkylsuccinic acid amide represented by the formula: The following chemical formula (II):

Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl-N′-docosylsuccinic acid amide represented by the formula: Reversible thermosensitive material having a sheet-like support, a heat-sensitive recording layer formed on the sheet-like support and containing a colorless or light-colored dye precursor, and a developer that reversibly develops and decolors the same. The recording material includes the Np- (1-hydroxy-2,2,2-trifluoroethyl) phenyl-N′-alkylsuccinamide according to claim 1 as the developer. Reversible thermosensitive recording material.