JP2014162166A - Reversible heat-sensitive recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reversible heat-sensitive recording medium excellent in film strength giving a good color optical density in erasing-printing after storage for a long period under a high-temperature and high-humidity environment.SOLUTION: A reversible heat-sensitive recording medium includes, on a substrate, a reversible heat-sensitive recording layer containing an ordinarily colorless or pale-colored dye precursor, and a reversible developer which forms relatively a colored state and an erased state by a difference in heating temperatures and/or cooling rates after heating. The reversible heat sensitive recording layer contains at least polyvinyl butyral and an isocyanate compound as binder species. A weight average molecular weight of the polyvinyl butyral is not less than 50,000, and a total unit ratio of hydroxyl groups and acetic acid groups to butyral groups of the polyvinyl butyral is 30-70 mass%.

Description

  The present invention uses a reversible thermosensitive coloring composition utilizing a coloring reaction between an electron-donating color-forming compound and an electron-accepting compound, and can control the formation of a color image and erase it by controlling thermal energy. The present invention relates to a reversible thermosensitive recording medium.

  Heat sensitivity utilizing a color development reaction between an electron donating color developing compound (hereinafter also referred to as a color former or a dye precursor) and an electron accepting compound (hereinafter also referred to as a developer). Recording media are widely known, and are widely used as output paper for facsimiles, word processors, scientific measuring instruments, etc., and recently as magnetic thermal cards, such as prepaid cards and point cards, with the progress of OA. Although such heat-sensitive recording media that have been put to practical use are being reviewed for recycling, reduction of usage, etc. due to environmental problems, they are irreversible color development. It cannot be used repeatedly, and new information can be added to a portion where no image is recorded, and the area of the recordable portion is limited. Therefore, the actual situation is that the amount of information to be recorded is reduced and the card is remade when the recording area is exhausted. Therefore, development of a reversible thermosensitive recording medium that can be rewritten any number of times is desired against the background of the dust problem and the deforestation problem in recent years.

  As a recording medium capable of reversibly developing and erasing, for example, a combination of gallic acid and phloroglucinol is used as a developer (see Patent Document 1), and phenolphthalein or thymol is used as the developer. Those using compounds such as phthalein (see Patent Document 2), those containing a homogeneous solution of color former, developer and carboxylic acid ester in the recording layer (see Patent Document 3), ascorbic acid derivatives in the developer Using a salt of bis (hydroxyphenyl) acetic acid or gallic acid and a higher aliphatic amine (see Patent Document 5).

  Furthermore, by using an organic phosphoric acid compound, aliphatic carboxylic acid compound or phenolic compound having a long-chain aliphatic hydrocarbon group as a developer, and combining this with a leuco dye as a color former, color development is achieved. Reversible thermosensitive coloring composition that can be easily erased under heating and cooling conditions, and can maintain its coloring and erasing states stably at room temperature, and can repeat coloring and erasing. A reversible thermosensitive recording medium using the recording material and the recording layer is known (see Patent Document 6). Thereafter, the use of a specific structure for a phenolic compound having a long-chain aliphatic hydrocarbon group (see Patent Document 7), reversible thermosensitive recording using a reversible thermosensitive recording layer containing a resin in a crosslinked state by an isocyanate compound A recording medium has been proposed (see Patent Document 8).

  However, the recording media described in Patent Documents 1 to 8 have problems such as a decrease in color density and dents (deformation of the printed portion) when repeated printing is repeated many times under actual use conditions.

  In order to improve this point, Patent Documents 9 to 16 propose a cured reaction product of polyvinyl butyral and an isocyanate compound in the reversible thermosensitive recording layer. However, when stored in a high temperature and high humidity environment for a long time, the film strength of the reversible thermosensitive recording layer is lowered, and there is a problem that the color density is insufficient in erasing and printing operations.

Japanese Patent Laid-Open No. 60-193691 Japanese Patent Laid-Open No. Sho 61-237684 JP-A-62-138568 Japanese Patent Laid-Open No. 63-173684 JP-A-2-188294 JP-A-5-124360 Japanese Patent Laid-Open No. 6-210954 JP-A-6-8626 Japanese Patent Laid-Open No. 9-254545 JP-A-10-226167 Japanese Patent Laid-Open No. 10-287049 JP-A-10-291370 JP-A-10-315627 Japanese Patent Laid-Open No. 11-198530 JP 2001-138630 A JP 2003-94820 A

  An object of the present invention is to provide a reversible thermosensitive recording medium excellent in film strength with good color density in erasure printing after being stored for a long time in a high temperature and high humidity environment.

  As a result of examining the configuration of the reversible thermosensitive recording layer of the reversible thermosensitive recording medium in order to solve these problems, the present inventors have found that the above-described problems can be solved by the following invention.

  Reversible containing a normally colorless or light dye precursor on a support and a reversible developer that forms a relatively colored state and an erased state due to differences in heating temperature and / or cooling rate after heating. In the reversible heat-sensitive recording medium having the heat-sensitive recording layer, the reversible heat-sensitive recording layer contains at least polyvinyl butyral and an isocyanate compound as binder species, and the polyvinyl butyral has a weight average molecular weight of 50,000 or more, and The reversible thermosensitive recording medium is characterized in that the total unit ratio of hydroxyl group and acetic acid group to butyral group of polyvinyl butyral is 30 to 70% by mass.

  According to the present invention, it is possible to provide a reversible thermosensitive recording medium excellent in film strength with good color density in erasing printing after being stored for a long time in a high temperature and high humidity environment.

  Claim 1 of the present invention is a reversibility in which a normally colorless or light-colored dye precursor is formed on a support, and a relatively colored state and an erased state are formed by a difference in heating temperature and / or cooling rate after heating. In a reversible thermosensitive recording medium having a reversible thermosensitive recording layer containing a developer, the reversible thermosensitive recording layer contains at least polyvinyl butyral and an isocyanate compound as binder species, and the polyvinyl butyral has a weight average molecular weight of 50. The total unit ratio of hydroxyl groups and acetic acid groups to butyral groups of the polyvinyl butyral is 30 to 70% by mass.

  According to the first aspect of the present invention, a normally colorless or pale dye precursor is formed on the support, and a relatively colored state and an erased state are formed by the difference in heating temperature and / or cooling rate after heating. In a reversible thermosensitive recording medium having a reversible thermosensitive recording layer containing a reversible developer, the reversible thermosensitive recording layer contains at least polyvinyl butyral and an isocyanate compound as binder species, and the weight average molecular weight of the polyvinyl butyral Is 50,000 or more, and the total unit ratio of the hydroxyl group and the acetate group to the butyral group of the polyvinyl butyral is 30 to 70% by mass, so that erasure printing after storage for a long time in a high temperature and high humidity environment Thus, it is possible to provide a reversible thermosensitive recording medium excellent in film strength with good color density.

  The reversible thermosensitive recording medium of the present invention contains at least polyvinyl butyral and an isocyanate compound as binder species, the polyvinyl butyral has a weight average molecular weight of 50,000 or more, and a hydroxyl group and an acetate group with respect to the butyral group of the polyvinyl butyral. The total unit ratio is 30 to 70% by mass. In either of the cases described above, there are cases in which a reversible thermosensitive recording medium having excellent film strength with good color density cannot be obtained in erasure printing after storage for a long time in a high temperature and high humidity environment. Therefore, the present inventors have found that a sufficient effect can be obtained by satisfying both of the above. The polyvinyl butyral is highly polymerized and has a high total unit ratio of hydroxyl group and acetic acid group, which contributes to the curing reaction with the isocyanate compound, and the crosslink density is increased to form a tough and low hygroscopic film. Guessed. Furthermore, it is good to add a polyol in it and to carry out a crosslinking reaction with an isocyanate group.

  The polyvinyl butyral according to the present invention has a weight average molecular weight of 50,000 or more, preferably a weight average molecular weight of 75,000 or more, and more preferably a weight average molecular weight of 100,000 or more. When it is less than 50,000, the film strength of the reversible thermosensitive recording layer is low, and the color density tends to deteriorate in erasure printing after the reversible thermosensitive recording medium is stored in a high temperature and high humidity environment.

  The polyvinyl butyral according to the present invention has a total unit ratio of hydroxyl group and acetic acid group to butyral group of 30 to 70% by mass, preferably 35 to 60% by mass, and more preferably 40 to 50% by mass. When it is less than 30% by mass and more than 70% by mass, the film strength of the reversible thermosensitive recording layer is low, and the color density tends to deteriorate in erasure printing after storing the reversible thermosensitive recording medium in a high temperature and high humidity environment. Become.

  The amount of polyvinyl butyral according to the present invention is preferably 0.05 to 50% by mass, more preferably 0.1 to 20% by mass, and further preferably 1 to 10% by mass with respect to the total mass of the reversible thermosensitive recording layer. . If it is less than 0.05% by mass, sufficient film strength of the reversible thermosensitive recording layer cannot be obtained, and the color density tends to deteriorate in erasure printing after storing the reversible thermosensitive recording medium in a high temperature and high humidity environment. There is sex. If the amount is more than 50% by mass, poor color development may occur.

  As an index of the film strength, it was confirmed by an adhesion test according to JIS K 5600-5-6 and repeated erasure printing of many times.

  The weight average molecular weight of the polyvinyl butyral according to the present invention can be measured both before and after the crosslinking reaction with the isocyanate group. The weight average molecular weight can be measured using, for example, an organic solvent-based SEC column GPC.

  The total unit ratio of the hydroxyl group and the acetate group to the butyral group according to the present invention is, for example, when the unit ratio of the hydroxyl group is 18 to 21% by mass and the unit ratio of the acetate group is 0 to 4% by mass in the catalog data. It calculated by following numerical formula (1) using each maximum value.

Formula (1) A = (B + C) / (100− (B + C))
A: Total unit ratio of hydroxyl group and acetate group to the butyral group (%)
B: Unit ratio of hydroxyl group (%)
C: Unit ratio of acetic acid group (%)

  Two or more types of polyvinyl butyral may be used in combination in the reversible thermosensitive recording layer of the present invention.

  The mixture of the polyvinyl butyral and the isocyanate compound according to the present invention may be used as it is when it is in a liquid state, but it can also be used after being diluted with a non-reactive solvent with the isocyanate compound. As the solvent that can be used, a solvent that dissolves polyvinyl butyral and an isocyanate compound and disperses and dissolves a dye precursor and a reversible developer is preferable. Specifically, the solvents exemplified in the method for incorporating the dye precursor and the reversible developer into the reversible thermosensitive recording layer coating liquid can be used. Among them, it is preferable to use an organic solvent that does not have active hydrogen reactive with an isocyanate compound. The crosslinking reaction between the polyvinyl butyral and the isocyanate compound may be performed at a reaction temperature of 30 to 160 ° C. and a reaction time of 1 minute to 120 hours. Needless to say, a long time is required when the reaction temperature is low, and a short time is required at a high temperature.

  A well-known thing can be used as an isocyanate compound concerning this invention. For example, aromatic aliphatic diisocyanates such as phenylene diisocyanate (PDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), 4,4'-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), hydrogenated TDI, water Polyhydric tri- or higher functional polyhydric diisocyanates such as aliphatic or alicyclic diisocyanates such as XDI, hydrogenated MDI, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) and their derivatives. In addition to isocyanate, various oligomers and polymers containing isocyanate may be mentioned. In the present invention, when xylylene diisocyanate or toluene diisocyanate is used as the isocyanate compound, the color density is preferably improved, and further, when xylylene diisocyanate having a high background whiteness (such as Takenate D-110N manufactured by Mitsui Chemicals) is used. preferable.

  The isocyanate compound according to the present invention may be used alone or in combination with one or more isocyanates with respect to one or more types of polyvinyl butyral. When a plurality of isocyanate compounds and polyvinyl butyrals are used, the combination may be arbitrary.

  Examples of the polyol include poly (meth) acrylic polyol, polyester polyol, polycarbonate polyol, polyester polycarbonate polyol, polyether polyol, alkyd polyol, caprolactone polyol, and silicone polyol.

  Poly (meth) acrylic polyol is a copolymer of acrylic acid, methacrylic acid and esters thereof, which contains a hydroxyl group, and the copolymer component containing a hydroxyl group includes hydroxyethyl acrylate, methacrylic acid. Hydroxyethyl acid, hydroxypropyl acrylate, hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate, allyl alcohol and the like are used. Examples of copolymer components other than acrylic acid, methacrylic acid and esters thereof include styrene, α-methylstyrene, vinyltoluene, acrylamide, methacrylamide and derivatives thereof, vinyl acetate, maleic anhydride and the like.

  Polyester polyol refers to a condensate of a polybasic acid and a polyhydric alcohol having a hydroxyl group. Polybasic acids used in these are phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid. , Aromatic polybasic acids such as trimesic acid, pyromellitic acid, naphthalenedicarboxylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, 2-methylsuccinic acid, 2-methyladipic acid, 3-methyladipic acid, 3-methylpentanedioic acid, 2-methyloctanedioic acid, 3,7-dimethyldecanedioic acid, 3,8-dimethyldecanedioic acid, There are aliphatic polybasic acids such as dimer acid, and acid anhydrides obtained from these polybasic acids are also used.

  Polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, propanediol, neopentyl glycol, glycerin, trimethylolethane, trimethylolpropane, diglycerol, pentaerythritol, dipentaerythritol, di In addition to low molecular weight polyols such as acetone glycol and hexanetriol, polyethylene glycol, polypropylene glycol, polybutylene glycol and the like are also used. In addition to the polyester polyols obtained from these, hydroxycarboxylic acids, or condensates or ring-opening polymerizations thereof of cyclic lactones such as polybutyrolactone polyols, polycaprolactone polyols, and higher fatty acids in addition to the above polybasic acids and polyhydric alcohols. There are alkyd polyols obtained by condensation. The polyether polyol is a polymer having a main chain composed of an ether bond, and includes polyethylene glycol, polypropylene glycol, polybutylene glycol, and these branched esters.

  Examples of polyether polyols include ethylene oxide and / or propylene oxide adducts of polyhydric alcohols, polytetramethylene glycol, and the like. Examples of the silicone polyol include silicone oils having a siloxane bond in the molecule and a terminal hydroxyl group.

  In addition, fluorine-containing polyols such as hydroxyl-containing fluoroolefin, polyol hydroxyl-terminated polybutadiene, polyisoprene, hydrogenated polybutadiene, hydrogenated polyisoprene, polyurethane and the like can be used. Further, low molecular weight polyols such as diethylene glycol, triethylene glycol, glycerol, trimethylolpropane, pentaerythritol, 1,4-cyclohexadiol, 1,4-dihydroxybenzene, bisphenol A, bisphenol F, and other aliphatic, fatty A cyclic, aromatic polyhydric alcohol or polyhydric phenol or a condensate thereof is used as a reactive diluent.

  As the polyol, caprolactone polyol and polyester polyol are preferable from the comprehensive evaluation of additive dispersibility, coatability, adhesiveness, heat resistance, film strength and the like.

  The mixture of the polyol and the isocyanate compound may be used as they are when they are in a liquid state, but can also be used after being diluted with an isocyanate compound and a non-reactive solvent. As a solvent that can be used, a solvent that dissolves a polyol and an isocyanate compound and disperses and dissolves a dye precursor and a reversible developer is preferable. Specifically, the solvents exemplified in the method for incorporating the dye precursor and the reversible developer into the reversible thermosensitive recording layer coating liquid can be used. Among them, it is preferable to use an organic solvent that does not have active hydrogen reactive with an isocyanate compound. Moreover, what is necessary is just to perform the crosslinking reaction of the said polyol and isocyanate compound at reaction temperature 30-160 degreeC, and reaction time 1 minute-120 hours. Needless to say, a long time is required when the reaction temperature is low, and a short time is required at a high temperature.

  The amount of the binder species used in the reversible thermosensitive recording layer of the present invention is preferably such that the mass percentage of the binder resin relative to the total mass of the reversible thermosensitive recording layer is in the range of 35% to 65%. If it is larger than this range, the color density may decrease significantly. On the other hand, if it is smaller than this range, the heat resistance and mechanical strength of the reversible thermosensitive recording layer may be lowered, the layer may be deformed, and the color density may be lowered. The mass percentage of the binder resin in the reversible thermosensitive recording layer is more preferably 40% to 60%, and particularly preferably 45% to 55%.

  The color image of the present invention may be formed by heating to a temperature at which it is once melt-mixed by a thermal head or the like and then rapidly cooling. In addition, erasing is one of a method of gradually cooling from a heated state and a method of heating to a temperature slightly lower than the coloring temperature. However, these are the same in the sense that both are phase-separated and at least one is temporarily maintained at a temperature at which it crystallizes. The reason for rapid cooling in the formation of the colored state is to prevent the temperature from being maintained at this phase separation temperature or crystallization temperature. Here, rapid cooling and slow cooling are relative to one composition, and the boundary thereof changes depending on the combination of the dye precursor and the reversible developer.

  Thus, the reversible thermosensitive recording layer can be erased by controlling the heating temperature and / or the cooling rate after heating.

  Specific examples of the reversible developer represented by the general formula (1) are given below, but the present invention is not limited thereto.

In the general formula (1), m represents an integer of 1 to 3, and n represents an integer of 20 or more. X includes a divalent group having a minimum structural unit of a —CO—, —NH—, or —SO ₂ — bond that does not contain a hydrocarbon group at both ends. Specific examples thereof include an amide (—CONH -, -NHCO-), urea (-NHCONH-), diacylamine (-CONHCO-), diacylhydrazine (-CONHNHCO-), oxalic acid diamide (-NHCOCONH-), acylurea (-CONHCONH-, -NHCONHCO-) , semicarbazide (-NHCONHNH -, - NHNHCONH-), acyl semicarbazide (-CONHNHCONH -, - NHCONHNHCO -) , 3- acyl carba Jin ester (-CONHNHCOO -, - OCONHNHCO-), sulfonamide (-NHSO ₂ -, - SO ₂ NH-), Suruhoniruhidora De _{(-SO 2 NHNHCO -, - CONHNHSO} 2 -) although groups such like, preferably a diacyl hydrazine.

  N- [2- (p-hydroxyphenyl) ethyl] henicosanamide, N- [2- (p-hydroxyphenyl) ethyl] docosanamide, N- [2- (p-hydroxyphenyl) ethyl] tricosanamide, N- [2- (p-hydroxyphenyl) ethyl] tetracosanamide, N- [2- (p-hydroxyphenyl) ethyl] pentacosanamide, N- [2- (p-hydroxyphenyl) ethyl] hexacosanamide N- [2- (p-hydroxyphenyl) ethyl] heptacosanamide, N- [2- (p-hydroxyphenyl) ethyl] octacosanamide, N- [2- (p-hydroxyphenyl) ethyl] nonacosane Amide, N- [2- (p-hydroxyphenyl) ethyl] triacontanamid.

  N-henicosyl- [3- (p-hydroxyphenyl)] propionamide, N-docosyl- [3- (p-hydroxyphenyl)] propionamide, N-tricosyl- [3- (p-hydroxyphenyl)] propionamide N-tetracosyl- [3- (p-hydroxyphenyl)] propionamide, N-pentacosyl- [3- (p-hydroxyphenyl)] propionamide, N-hexacosyl- [3- (p-hydroxyphenyl)] propion Amides, N-heptacosyl- [3- (p-hydroxyphenyl)] propionamide, N-octacosyl- [3- (p-hydroxyphenyl)] propionamide, N-nonacosyl- [3- (p-hydroxyphenyl)] Propionamide, N-triacontyl- [3- (p-hydroxyl Yl)] propionamide.

  N- [2- (p-hydroxyphenyl) ethyl] -N'-henicosyl urea, N- [2- (p-hydroxyphenyl) ethyl] -N'-docosyl urea, N- [2- (p-hydroxyphenyl) ) Ethyl] -N'-tricosyl urea, N- [2- (p-hydroxyphenyl) ethyl] -N'-tetracosyl urea, N- [2- (p-hydroxyphenyl) ethyl] -N'-pentacosyl urea, N- [2- (p-hydroxyphenyl) ethyl] -N'-hexacosyl urea, N- [2- (p-hydroxyphenyl) ethyl] -N'-heptacosyl urea, N- [2- (p-hydroxyphenyl) ) Ethyl] -N'-octacosylurea, N- [2- (p-hydroxyphenyl) ethyl] -N'-nonacosylurea, N- [2- (p-hydroxyphenyl) ethyl] N'- triacontyl urea.

  N- [3- (p-hydroxyphenyl) propiono] -N'-henicosanohydrazide, N- [3- (p-hydroxyphenyl) propiono] -N'-docosanohydrazide, N- [3- (p -Hydroxyphenyl) propiono] -N'-tricosanohydrazide, N- [3- (p-hydroxyphenyl) propiono] -N'-tetracosanohydrazide, N- [3- (p-hydroxyphenyl) propiono]- N'-pentacosanohydrazide, N- [3- (p-hydroxyphenyl) propiono] -N'-hexacosanohydrazide, N- [3- (p-hydroxyphenyl) propiono] -N'-heptacosano Hydrazide, N- [3- (p-hydroxyphenyl) propiono] -N'-octacosanohydrazide, N- [3- (p-hydroxypheny ) Puropiono]-N'-Bruno Naco Sano hydrazide, N- [3- (p- hydroxyphenyl) Puropiono]-N'-triacontanyl Bruno hydrazide.

  The amount of the reversible developer used in the present invention is preferably in the range of 5 to 5000% by mass, more preferably 10 to 3000% by mass, based on the dye precursor.

  In the reversible thermosensitive recording medium of the present invention, an erasure accelerator is preferably added for the purpose of improving erasability. Although a preferable example is shown below, this invention is not limited to this.

  1,1-dimethyl-4-dodecyl semicarbazide, 1,1-dimethyl-4-octadecyl semicarbazide, 1,1-diethyl-4-icosyl semicarbazide, 1,1-dipropyl-4-tetracosyl semicarbazide, 1,1 -Diethyl-4-nonacosyl semicarbazide, 1-methyl-1-propyl-4-hexatriacontyl semicarbazide.

  N- (1-pyrrolidinyl) -N'-dodecylurea, N- [1- (3-methyl) imidazolio] -N'-tetradecylurea, N- (1-pyrazolyl) -N'-octadecylurea, N- ( 3-thiazolidinio) -N'-octadecylurea, N- (1-pyrrolyl) -N'-icosylurea, N- (1-imidazolyl) -N'-tetracosylurea, N- (1-pyrrolidinyl) -N'- Nonacosyl urea, N- (1-pyrrolyl) -N'-hexatriacontyl urea.

  N- (1-piperidyl) -N′-dodecylurea, N- (1-piperidyl) -N′-tetradecylurea, N- [1- (2,6-dimethyl) piperidyl] -N′-pentadecylurea, N -(4-morpholinyl) -N'-octadecylurea, N- (4-morpholinyl) -N'-icosylurea, N- [4- (2,6-dimethyl) morpholinyl] -N'-tetracosylurea, N- (4-thiomorpholinyl) -N′-hexacosyl urea, N- [1- (4-methyl) piperazinyl] -N′-nonacosyl urea, N- [1- (4-methyl) piperazinyl] -N′-triacontyl urea, N- (1-piperazinyl) -N'-hexatriacontylurea, N- (1- (4-methyl) piperazinyl) -N'-octadecylurea.

  The amount of the erasure accelerator used in the present invention is 0.05 to 1000% by mass, preferably 0.05 to 500% by mass, more preferably 0.05 to 200% by mass, based on the dye precursor. If the amount of erasure accelerator is too small relative to the dye precursor, the erasability (erase accelerating property) tends to deteriorate, and conversely if too much erasing accelerator is present, the color density tends to decrease due to the dilution effect.

  Furthermore, the normally colorless to light-colored dye precursor contained in the reversible thermosensitive recording medium of the present invention is not particularly limited and may be appropriately selected depending on the intended purpose. For example, leuco dyes and the like are preferable. . As the leuco dye, a fluorane compound or an azaphthalide compound can be preferably used. Hereinafter, although the specific example of a dye precursor is given, this invention is not limited to this.

  2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6- (di-n-butylamino) fluorane, 2-anilino-3-methyl-6- (di-n-amylamino) ) Fluorane, 2-anilino-3-methyl-6- (diisoamylamino) 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- (N -N-amyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (N-sec-butyl-N-methylamino) fluorane, 2-anilino-3 Methyl-6- (Nn-amyl-N-ethylamino) fluorane, 2-anilino-3-methyl-6- (N-isoamyl-N-ethylamino) fluorane, 2-anilino-3-methyl-6 (Nn-propyl-N-isopropylamino) fluorane, 2-anilino-3-methyl-6- (N-cyclohexyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (N-ethyl) -P-Toluidino) fluoran, 2-anilino-3-methyl-6- (N-methyl-p-toluidino) fluoran.

  2- (m-trichloromethylanilino) -3-methyl-6-diethylaminofluorane, 2- (m-trifluoromethylanilino) -3-methyl-6-diethylaminofluorane, 2- (m-trichloromethyl) Anilino) -3-methyl-6- (N-cyclohexyl-N-methylamino) fluorane, 2- (2,4-dimethylanilino) -3-methyl-6-diethylaminofluorane, 2- (2,4 -Dimethylanilino) -3-methyl-6- (di-n-butylamino) fluorane, 2- (m-toluidino) -3-methyl-6-diethylaminofluorane, 2- (m-toluidino) -3- Methyl-6- (di-n-butylamino) fluorane, 2- (p-toluidino) -3-methyl-6-diethylaminofluorane, 2- (p-toluidino) -3- Tyl-6- (di-n-butylamino) fluorane, 2- (N-ethyl-p-toluidino) -3-methyl-6- (N-ethylanilino) fluorane, 2- (N-ethyl-p-toluidino) -3-methyl-6- (N-propyl-p-toluidino) fluorane, 2-anilino-6- (Nn-hexyl-N-ethylamino) fluorane, 2- (o-chloroanilino) -6-diethylaminofluor Oran, 2- (o-chloroanilino) -6- (di-n-butylamino) fluorane, 2- (m-trifluoromethylanilino) -6-diethylaminofluorane, 2,3-dimethyl-6-dimethylamino Fluorane, 3-methyl-6- (N-ethyl-p-toluidino) fluorane, 2-chloro-6-diethylaminofluorane.

  2-bromo-6-diethylaminofluorane, 2-chloro-6- (di-n-propylamino) fluorane, 3-chloro-6-cyclohexylaminofluorane, 3-bromo-6-cyclohexylaminofluorane, 2- Chloro-6- (N-ethyl-N-isoamylamino) fluorane, 2-chloro-3-methyl-6-diethylaminofluorane, 2-anilino-3-chloro-6-diethylaminofluorane, 2- (o-chloroanilino) ) -3-Chloro-6-cyclohexylaminofluorane, 2- (m-trifluoromethylanilino) -3-chloro-6-diethylaminofluorane, 2- (2,3-dichloroanilino) -3-chloro -6-diethylaminofluorane, 1,2-benzo-6-diethylaminofluorane, 3-diethylamino- - (m-trifluoromethyl) -6-fluoran.

  3- (1-Ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-Ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-octyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4- Azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-methyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3- Yl) -3- (2-methyl-4-diethylaminophenyl) -7-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-diethyl) Aminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- [4- (Nn-amyl-N-methylamino) phenyl] -4-azaphthalide, 3 -(1-Methyl-2-methylindol-3-yl) -3- (2-hexyloxy-4-diethylaminophenyl) -4-azaphthalide, 3,3-bis (2-ethoxy-4-diethylaminophenyl)- 4-Azaphthalide, 3,3-bis (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide.

  3- (p-Toluidino) -2-methyl-8-pyrrolidinofluorane, 2- (p-acetylanilino) -6- (Nn-amyl-Nn-butylamino) fluorane, 2-benzyl Amino-6- (N-ethyl-p-toluidino) fluorane, 2-benzylamino-6- (N-methyl-2,4-dimethylanilino) fluorane, 2-benzylamino-6- (N-ethyl-2) , 4-Dimethylanilino) fluorane, 2-benzylamino-6- (N-methyl-p-toluidino) fluorane, 2-bis (p-methylbenzylamino) -6- (N-ethyl-p-toluidino) fluorane 2-([alpha] -phenylethylamino) -6- (N-ethyl-p-toluidino) fluorane.

  2-methylamino-6- (N-methylanilino) fluorane, 2-methylamino-6- (N-ethylanilino) fluorane, 2-methylamino-6- (Nn-propylanilino) fluorane, 2-ethylamino -6- (N-methyl-p-toluidino) fluorane, 2-methylamino-6- (N-methyl-2,4-dimethylanilino) fluorane, 2-ethylamino-6- (N-ethyl-2, 4-dimethylanilino) fluorane, 2-dimethylamino-6- (N-methylanilino) fluorane, 2-dimethylamino-6- (N-ethylanilino) fluorane, 2-diethylamino-6- (N-methyl-p-toluidino ) Fluorane, 2-diethylamino-6- (N-ethyl-p-toluidino) fluorane, 2- (di-n-propylamino)- - (N-methylanilino) fluoran, 2- (di -n- propylamino)-6-(N-ethylanilino) fluoran.

  2-amino-6- (N-methylanilino) fluorane, 2-amino-6- (N-ethylanilino) fluorane, 2-amino-6- (Nn-propylanilino) fluorane, 2-amino-6- ( N-methyl-p-toluidino) fluorane, 2-amino-6- (N-ethyl-p-toluidino) fluorane, 2-amino-6- (Nn-propyl-p-toluidino) fluorane, 2-amino- 6- (N-methyl-p-ethylanilino) fluorane, 2-amino-6- (N-ethyl-p-ethylanilino) fluorane, 2-amino-6- (Nn-propyl-p-ethylanilino) fluorane, 2 -Amino-6- (N-methyl-2,4-dimethylanilino) fluorane, 2-amino-6- (N-ethyl-2,4-dimethylanilino) fluorane, 2 Amino-6- (Nn-propyl-2,4-dimethylanilino) fluorane, 2-amino-6- (N-methyl-p-chloroanilino) fluorane, 2-amino-6- (N-ethyl-p -Chloroanilino) fluoran, 2-amino-6- (Nn-propyl-p-chloroanilino) fluorane, 1,2-benzo-6- (N-ethyl-N-isoamylamino) fluorane, 1,2-benzo- 6- (Di-n-butylamino) fluorane, 1,2-benzo-6- (N-methyl-N-cyclohexylamino) fluorane, 1,2-benzo-6- (N-ethyl-p-toluidino) fluorane .

  4,4'-bis (dimethylaminophenyl) benzhydrylbenzyl ether, N-chlorophenyl leucooramine, N-2,4,5-trichlorophenyl leucooramine, benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue, 3 -Methylspirodinaphthopyrans, 3-ethylspirodinaphthopyrans, 3,3'-dichlorospirodinaphthopyrans, 3-benzylspirodinaphthopyrans, 3-methylnaphthyl (3-methoxybenzo) spiropyrans, 3-propylspiros Benzopyran.

  These dye precursors may be used singly or in combination of two or more, and toning can also be performed by mixing dye precursors that develop colors in other colors. Also, a multicolor reversible thermosensitive recording medium or a full-color reversible thermosensitive recording medium can be obtained by laminating layers that develop colors of different colors or arranging them on a plane. The dye precursor may be subjected to processing such as microencapsulation, resin coating, and composite particle formation with a resin.

  The support used in the present invention includes paper, non-woven fabric / woven fabric / knitted fabric, plastic film, resin-coated paper, synthetic paper, metal plate, metal foil, glass, quartz glass, silicon resin, aluminum oxide, silicon oxide Etc., or a combination of these can be arbitrarily used depending on the purpose. Examples of the plastic film that can be used in the present invention include polyester film, polyolefin film, polyvinyl alcohol film, polyvinyl chloride film, nylon film, polystyrene film, polyvinylidene chloride film, ethylene-vinyl acetate copolymer film, ethylene-vinyl. Examples include alcohol copolymer films, fluororesin films, polyimide films, aromatic polyamide films, acrylic (based) resin films, and polycarbonate films. A polyester film is preferable in terms of mechanical strength, smoothness, water resistance, solvent resistance, and heat resistance. These synthetic resin materials may be used alone or in combination of two or more.

  Examples of the polyester film include polyethylene terephthalate (PET), polybutylene terephthalate, poly-1,4-cyclohexanedimethylene terephthalate, polyxylylene terephthalate, polyethylene isophthalate, polyethylene-2,6-naphthalate (PEN). It is done. Preferred polyester films include PET films or PEN films that are excellent in toughness, heat resistance, chemical resistance, dimensional stability, transparency, and electrical insulation.

  The support may be opaque, translucent or transparent. In order to make the background appear white or other specific colors, a white pigment, a colored dye pigment, or air bubbles may be included in the support or on the surface. When the affinity when a coating layer such as a reversible thermosensitive recording layer is provided on the support is low, the support is obtained by corona discharge treatment, oxidation reaction treatment (chromic acid, etc.), etching treatment, easy adhesion treatment, antistatic treatment, etc. A modification treatment may be performed on the surface. There is no restriction | limiting in particular about a shape, a structure, a magnitude | size, etc. as a support body which concerns on this invention. Examples of the shape include a flat plate shape and a roll shape. The structure may be a single layer structure or a laminated structure, and the size can be appropriately selected according to the use of the reversible thermosensitive recording medium.

  The thickness of the support used in the present invention can be appropriately selected according to the application of the reversible thermosensitive recording medium, but is preferably 10 to 2000 μm, more preferably 20 to 1000 μm.

  The reversible thermosensitive recording layer of the present invention is formed by applying and forming a reversible thermosensitive recording layer coating solution containing at least a dye precursor and a reversible developer on at least one surface of a support. The As a method for including the dye precursor and the reversible developer in the reversible thermosensitive recording layer coating solution, each compound is dissolved in a solvent alone or dispersed in a dispersion medium and then mixed. Are mixed in a solvent and then dissolved in a solvent or dispersed in a dispersion medium, each compound is heated and dissolved, homogenized and then cooled, dissolved in a solvent or dispersed in a dispersion medium, and the like. It is not something. If necessary, a dispersing agent may be used during dispersion.

  As a solvent or dispersion medium, water; alcohols such as methanol, ethanol, n-propanol, 2-propanol, n-butanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone; methyl acetate, ethyl acetate , Esters such as butyl acetate, isobutyl acetate, isopropyl acetate, ethyl lactate and ethylene carbonate; ethers such as diethyl ether, glycol dimethyl ether, glycol diethyl ether, dioxane, dioxolane and tetrahydrofuran; aroma such as benzene, toluene, xylene and styrene Group hydrocarbons; aliphatic hydrocarbons such as pentane, hexane and cyclohexane; methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, chlorobenzene Halogenated hydrocarbons such as dichlorobenzene; N, N- dimethylformamide, N, etc. amides such as N- dimethylacetamide can be used.

  For a reversible thermosensitive recording layer coating liquid, a leveling agent, a dispersant, a hardener, a surfactant, a thickener, and an antifoaming agent are used for the purpose of improving coating properties or recording characteristics as necessary. Erasing modifiers, antioxidants, anti-aging agents, fillers, pigments, lubricants, antistatic agents, ultraviolet absorbers, infrared absorbers, coloring dyes, fluorescent whitening agents, thermofusible substances, preservatives, etc. It can be contained in the reversible thermosensitive recording layer. Further, if necessary, a heat fusible substance can be added as an erasure control agent for the reversible thermosensitive recording layer.

  When the reversible thermosensitive recording layer contains a curable resin, heating, ultraviolet irradiation, and electron beam irradiation are performed. Ultraviolet irradiation can be performed using a known ultraviolet irradiation device, and examples thereof include a light source, a lamp, a power source, a cooling device, and a conveying device. Examples of the light source include a mercury lamp, a metal halide lamp, a gallium lamp, a mercury xenon lamp, and a flash lamp. The wavelength of the light source can be appropriately selected according to the ultraviolet absorption wavelength of the photopolymerization initiator and the photopolymerization accelerator. The output and conveying speed of the ultraviolet irradiation are determined according to the irradiation energy necessary for crosslinking the ultraviolet curable resin.

  As an erasing modifier added for the purpose of improving the erasability of the reversible thermosensitive recording layer, those having a melting point of 60 ° C. to 200 ° C. are preferred, and those having a melting point of 80 ° C. to 180 ° C. are particularly preferred. Sensitizers used for general heat-sensitive recording paper can also be used. For example, waxes such as N-hydroxymethyl stearic acid amide, behenic acid amide, stearic acid amide, and palmitic acid amide, naphthol derivatives such as 2-benzyloxynaphthalene, and biphenyl derivatives such as p-benzylbiphenyl and 4-allyloxybiphenyl 1, 2-bis (3-methylphenoxy) ethane, 2,2′-bis (4-methoxyphenoxy) diethyl ether, polyether compounds such as bis (4-methoxyphenyl) ether, diphenyl carbonate, dibenzyl oxalate, Carbonic acid or oxalic acid diester derivatives such as bis (p-methylbenzyl) oxalate can be used in combination.

  Anti-aging agents added for the purpose of preventing aging of the reversible thermosensitive recording layer include amine compounds such as p, p'-diaminodiphenylmethane, aldol-α-naphthylamine, and N, N'-diphenyl-p-phenylenediamine. , Hydroquinone monobenzyl ether, phenol compounds such as 1,1-bis (p-hydroxyphenyl) cyclohexane, benzotriazole compounds, triazine compounds, benzophenone compounds, benzoates and the like. In addition, o-phenylenethiourea, zinc salt of 2-aminobenzimidazole, nickel dibutylthiocarbamate, zinc oxide, paraffin and the like can be mentioned. In addition, a polymer containing these monomers having an anti-aging structure as a component of polymerization, and a polymer main chain grafted with an anti-aging structure can also be used. Two or more types of anti-aging agents can be used in combination.

  Examples of pigments that can be added to the reversible thermosensitive recording layer include, for example, carbonates such as aluminum, zinc, calcium, magnesium, barium, and titanium, oxides, hydroxides, sulfates, etc., and zeolite, silica, Inorganic pigments containing clays such as kaolin, calcined kaolin and talc, starch, styrene resin, polyolefin resin, urea-formalin resin, melamine resin, acrylic resin, paraffin, natural wax, synthetic wax and the like can be used. Further, higher fatty acid metal salts such as zinc stearate and calcium stearate can be used as a lubricant.

  The film thickness of the reversible thermosensitive recording layer of the present invention is determined by its composition and the desired color density, and specifically, it is preferably in the range of 0.5 to 20 μm, more preferably 3 to 15 μm.

  For the purpose of enhancing durability during repeated use, it is preferable to provide a protective layer on the reversible thermosensitive recording layer. The protective layer may be composed of a single layer or a plurality of layers of two layers or three or more layers. The protective layer preferably contains a curable resin such as a thermosetting resin, an electron beam curable resin, or an ultraviolet curable resin, and particularly preferably an electron beam curable resin or an ultraviolet curable resin. As the curable resin, resins exemplified as binder resins that can be used in the reversible thermosensitive recording layer can be used. Further, a pigment may be blended for the purpose of further improving durability or adjusting the glossiness, or a higher fatty acid metal salt or the like may be blended as a lubricant. As the pigment and the higher fatty acid metal salt, the compounds exemplified in the reversible thermosensitive recording layer can be used.

  The thickness of the protective layer is preferably in the range of 0.1 to 10 μm, more preferably 0.5 to 5 μm. When the film thickness exceeds 10 μm, not only the effect is saturated, but also the sensitivity of the reversible thermosensitive recording layer tends to decrease. When the film thickness is smaller than 0.1 μm, it is difficult to obtain the expected coating layer strength, and the coating layer is easily damaged.

  In the present invention, an intermediate layer may be provided between the reversible thermosensitive recording layer and the protective layer, between the support and the heat insulating layer, or between the heat insulating layer and the reversible thermosensitive recording layer. Further, a light reflection layer or an air layer may be provided. The intermediate layer may contain an ultraviolet absorber. In the case where the reversible thermosensitive recording layer is provided only on one side of the support, a back coat layer may be provided on the other side. Examples of the ultraviolet absorber include a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, and a salicylic acid phenyl ester ultraviolet absorber. These layers may be composed of a single layer or a plurality of layers of two or more layers. Moreover, it is preferable that these layers contain curable resins, such as a thermosetting resin, an electron beam curable resin, and an ultraviolet curable resin.

  In the present invention, a protective layer, an intermediate layer and the like provided on the support are optionally provided with a leveling agent, a dispersant, a hardener, a surfactant, a thickener, an antiseptic, a filler, a coloring dye. Various additives such as pigments, fluorescent brighteners, ultraviolet absorbers, infrared absorbers, antioxidants, anti-aging agents, pH adjusters, antifoaming agents, pigments, lubricants and antistatic agents can be added.

  The reversible thermosensitive recording medium of the present invention may be provided with a printing recording layer such as printing such as offset printing and gravure printing; an ink jet recording layer, a thermal transfer image receiving layer, and a sublimation type thermal transfer image receiving layer. These print and print recording layers may be provided by being laminated with the reversible thermosensitive recording layer, or may be provided on a part of the same surface as the reversible thermosensitive recording layer. Further, it may be provided on a part of or the entire surface opposite to the surface provided with the reversible thermosensitive recording layer. An overprint varnish (OP varnish) layer mainly composed of a curable resin may be provided partially or entirely on the print recording layer.

  In the reversible thermosensitive recording medium of the present invention, in the reversible thermosensitive recording layer, other layers, the surface provided with the reversible thermosensitive recording layer, the opposite surface, etc. are electrically, magnetically and optically information. May contain a recordable material. Further, the support may be a multilayer and an IC chip may be sandwiched between them. Further, an antistatic layer can be provided on one side or both sides for the purpose of antistatic. The reversible thermosensitive recording medium of the present invention can be attached to another medium through an adhesive layer or the like or using a heat-fusible resin as a support.

  When the IC chip is encapsulated between the layers of the reversible thermosensitive recording medium, for example, it can be encapsulated between the layers of the plastic film or between the paper substrate and the plastic film. It is preferable from the viewpoint of print quality that sealing is performed between layers away from the reversible thermosensitive recording layer. When a non-contact IC chip is encapsulated, it can be encapsulated with an antenna. A cushion layer can be provided for the purpose of preventing the IC chip from being damaged by the pressure during encapsulation. The thickness of the cushion layer is preferably 10 μm or more because cushioning properties are insufficient if it is less than 10 μm. Since the load is applied to the joint between the IC chip and the antenna, the area of the cushion layer is preferably large enough to cover the IC chip and the antenna joint. The cushion layer can be provided on one side or both sides. More preferably, cushion layers are provided on both sides. As the cushion layer, a thermoplastic resin is preferable, and if it is a foamed resin, the cushioning property is better, so that the IC chip can be prevented from being damaged.

  The method for laminating each layer in the present invention on a support to form a reversible thermosensitive recording medium is not particularly limited, and can be formed by a conventional method. For example, air knife coater, blade coater, bar coater, curtain coater, gravure roll and transfer roll coater, roll coater, comma coater, smoothing coater, micro gravure coater, reverse roll coater, 4 roll roll coater, dip coater, Various coating machines such as a rod coater, a kiss coater, a gate roll coater, a squeeze coater, a slide coater, a die coater and other smearing apparatuses, a planographic plate, a relief plate, an intaglio plate, a flexo, a gravure, a screen, and a hot melt can be used. Furthermore, each layer can be held by ultraviolet irradiation or electron beam irradiation, aging by heating, or the like, in addition to a normal drying step. By these methods, it is possible to apply and print one layer at a time or multiple layers simultaneously.

  In the reversible thermosensitive recording medium of the present invention, it is sufficient that rapid cooling occurs after heating in order to form a color recording image, and a slow cooling rate after heating is sufficient in order to erase the recorded image. For example, after heating by an appropriate method, a colored state can be developed by rapidly cooling by pressing a low-temperature metal block or the like. In addition, if the heating is performed for a very short time using a thermal head, laser light, or the like, the cooling is performed immediately after the heating is completed, so that the colored state can be maintained. On the other hand, when heated for a relatively long time with a suitable heat source (thermal head, laser light, heat roll, heat stamp, high-frequency heating, electric heater, radiant heat from a light source such as a tungsten lamp or a halogen lamp, hot air, etc.) Since not only the layer but also the support and the like are heated, even if the heat source is removed, the cooling rate is slow and the erased state is obtained. Therefore, even when the same heating temperature and the same heat source are used, the coloring state and the erasing state can be arbitrarily expressed by controlling the cooling rate.

  Examples of the laser used for heating include, but are not limited to, a semiconductor laser, a YAG laser, and a carbon dioxide gas laser. In order to efficiently perform heating with a semiconductor laser or YAG laser, a reversible thermosensitive recording layer contains a photothermal conversion material having absorption in the near infrared region, or a photothermal conversion layer containing a photothermal conversion material is reversible. It is preferably provided directly adjacent to the thermal recording layer. Examples of photothermal conversion materials having absorption in the near infrared region include, for example, metal or metalloid layers such as platinum, titanium, silicon, chromium, nickel, germanium, and aluminum, immonium compounds, metal complex compounds, cyanine dyes, squarylium dyes, Photothermal conversion dyes such as naphthoquinone dyes, phthalocyanine compounds, and polymethine compounds can be used, and can be contained in the reversible thermosensitive recording layer in a dispersed state or in a molecular state. Preferable photothermal conversion dyes include phthalocyanine compounds and metal complex compounds in terms of photothermal conversion efficiency, solubility in solvents, dispersibility in resins, and light resistance to ultraviolet light, and phthalocyanine compounds are particularly preferable. When the photothermal conversion layer is provided in the vicinity of the reversible thermosensitive recording layer, a photothermal conversion layer made of a metal film such as a copper thin film or ITO can also be used.

  Examples of phthalocyanine compounds include naphthalocyanine compounds, metal-free phthalocyanine compounds, iron phthalocyanine compounds, copper phthalocyanine compounds, zinc phthalocyanine compounds, nickel phthalocyanine compounds, vanadyl phthalocyanine compounds, indium chloride phthalocyanine compounds, tin phthalocyanine compounds, and more preferably. Are vanadyl phthalocyanine compounds, zinc phthalocyanine compounds, and tin phthalocyanine compounds. The phthalocyanine compound used in the present invention may have a substituent on the aromatic ring for the purpose of adjusting the absorption wavelength, improving the solubility in a solvent, improving light resistance, and the like. Examples of the substituent include an alkyl ether group, an alkyl thioether group, an aryl ether group, an aryl thioether group, an amide group, an amino group, an alkyl ester group, an aryl ester group, a chlorine atom, and a fluorine atom. When there are two or more substituents on the aromatic ring, they may be the same or different, and the substituents may be bonded to form a ring.

  The amount of the photothermal conversion dye used is preferably set so that the absorbance at the oscillation wavelength of the light source used is 0.2 or more. If it is less than this amount, sufficient heat generation cannot be obtained, and the recording sensitivity is lowered. On the other hand, the photothermal conversion dye has some absorption in the visible region, and if the amount used is too large, the contrast is lowered. It is preferable to set an upper limit for the amount of photothermal conversion dye used so that an average transmittance of 400 nm to 700 nm can be secured by 60% or more. Two or more kinds of photothermal conversion dyes can be mixed and used.

  The photothermal conversion dye is preferably contained in at least one of the same layer or adjacent layers with respect to the layer containing the leuco dye and the reversible developer, and preferably contained in the same layer. It is more preferable for obtaining sensitivity.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this Example. In addition, the number of parts in an Example is a mass reference | standard.

(A) Preparation of reversible thermosensitive recording layer coating solution As a dye precursor, 30 parts of 2- (p-toluidino) -3-methyl-6-diethylaminofluorane, and as a reversible developer, N- [3- ( p-hydroxyphenyl) propiono] -N'-docosanohydrazide, 100 parts of N- [1- (4-methyl) piperazinyl] -N'-octadecylurea as an erasure accelerator, polyvinyl butyral (active ingredients: 100 parts by mass, weight average molecular weight: 100,000, 5 parts of total unit ratio of hydroxyl group and acetic acid group to butyral group: 40 parts by mass, caprolactone polyol (manufactured by Daicel, trade name: PLACEL 303, active ingredient: 100 mass%) Disperse 30 parts of methyl ethyl ketone 1,000 parts together with glass beads in paint shaker for 5 hours to obtain dispersion It was. 110 parts of an isocyanate compound (manufactured by Mitsui Chemicals, trade name: Takenate D-110N, active ingredient: 75% by mass) was added to the dispersion thus obtained and mixed well to prepare a reversible thermosensitive recording layer coating solution. .

(B) Coating of reversible thermosensitive recording layer coating solution The reversible thermosensitive recording layer coating solution obtained in (A) is dried on a white polyethylene terephthalate (PET) sheet having a thickness of 125 μm so that the film thickness after drying is 8 μm. The coating was dried at 95 ° C. for 1 minute, and further cured by heating at 50 ° C. for 48 hours to provide a reversible thermosensitive recording layer.

(C) Preparation of intermediate layer coating solution 50 parts of 2,2'-methylenebis [6- (2H-benzotriazol-2-yl) -4- (2-hydroxyethyl) phenol] as a UV absorber, polyester polyol (DIC) A mixture of 100 parts by trade name, Barnock 11-408, 70% by mass of active ingredient) and 800 parts of methyl ethyl ketone was dispersed together with glass beads by a paint shaker for 5 hours to obtain a dispersion. To the dispersion thus obtained, 140 parts of an isocyanate compound (trade name: Takenate D-110N, active ingredient 75% by mass, manufactured by Mitsui Chemicals, Inc.) and 50 parts of methyl ethyl ketone were added and mixed well to prepare an intermediate layer coating solution. .

(D) Coating of intermediate layer coating liquid On the reversible thermosensitive recording layer coated surface of the coated sheet prepared in (B), the film thickness after drying the intermediate layer coating liquid obtained in (C) is 1 μm. After coating at 95 ° C. for 1 minute, the coating was further cured by heating at 50 ° C. for 48 hours to provide an intermediate layer.

(E) Preparation of coating liquid for protective layer Urethane acrylate UV curable resin (manufactured by DIC, trade name: Unidic 17-813, active ingredient: 80% by mass) 12.5 parts, wet method silica (manufactured by Fuji Silysia Chemical Ltd.) , Trade name: Silicia 350) 2.0 parts and butyl acetate 10 parts were mixed. The liquid mixture thus obtained was treated with a bead mill to prepare a protective layer coating solution.

(F) Application of protective layer coating solution On the intermediate layer coating surface of the coating sheet prepared in (D), apply the protective layer coating solution obtained in (E) so that the film thickness after drying is 2 μm. And dried at 95 ° C. for 1 minute, and then cured by passing under an ultraviolet lamp with an irradiation energy of 120 W / cm at a conveyance speed of 10 m / min to provide a protective layer, whereby the reversible thermosensitive recording medium of Example 1 was obtained. It was.

(Example 2)
A reversible thermosensitive recording medium of Example 2 was obtained in the same manner as in Example 1 except that the number of parts of polyvinyl butyral in Example 1 (A) was changed to 0.25 part.

(Example 3)
A reversible thermosensitive recording medium of Example 3 was obtained in the same manner as in Example 1 except that the number of parts of polyvinyl butyral was 2.5 parts in Example 1 (A).

Example 4
A reversible thermosensitive recording medium of Example 4 was obtained in the same manner as in Example 1 except that the number of parts of polyvinyl butyral was 25 in Example 1 (A).

(Example 5)
A reversible thermosensitive recording medium of Example 5 was obtained in the same manner as in Example 1 except that the number of parts of polyvinyl butyral in Example 1 (A) was changed to 50 parts.

(Example 6)
In Example 1 (A), instead of using 5 parts of polyvinyl butyral having a total unit ratio of hydroxyl group and acetate group to butyral group of 40% by mass, the total unit ratio of hydroxyl group and acetate group to butyral group is 30% by mass. A reversible thermosensitive recording medium of Example 6 was obtained in the same manner as in Example 1 except that 5 parts of certain polyvinyl butyral was used.

(Example 7)
In Example 1 (A), instead of using 5 parts of polyvinyl butyral having a total unit ratio of hydroxyl group and acetate group to butyral group of 40% by mass, the total unit ratio of hydroxyl group and acetate group to butyral group is 35% by mass. A reversible thermosensitive recording medium of Example 7 was obtained in the same manner as in Example 1 except that 5 parts of a certain polyvinyl butyral was used.

(Example 8)
In Example 1 (A), instead of using 5 parts of polyvinyl butyral having a total unit ratio of hydroxyl group and acetate group to butyral group of 40% by mass, the total unit ratio of hydroxyl group and acetate group to butyral group is 50% by mass. A reversible thermosensitive recording medium of Example 8 was obtained in the same manner as in Example 1 except that 5 parts of certain polyvinyl butyral was used.

Example 9
In Example 1 (A), instead of using 5 parts of polyvinyl butyral having a total unit ratio of hydroxyl group and acetate group to butyral group of 40% by mass, the total unit ratio of hydroxyl group and acetate group to butyral group is 60% by mass. A reversible thermosensitive recording medium of Example 9 was obtained in the same manner as in Example 1 except that 5 parts of a certain polyvinyl butyral was used.

(Example 10)
In Example 1 (A), instead of using 5 parts of polyvinyl butyral having a total unit ratio of hydroxyl group and acetate group to butyral group of 40% by mass, the total unit ratio of hydroxyl group and acetate group to butyral group is 70% by mass. A reversible thermosensitive recording medium of Example 10 was obtained in the same manner as in Example 1 except that 5 parts of certain polyvinyl butyral was used.

(Example 11)
Example 1 (A) was carried out in the same manner as in Example 1 except that 5 parts of polyvinyl butyral having a weight average molecular weight of 50,000 was used instead of 5 parts of polyvinyl butyral having a weight average molecular weight of 100,000. 11 reversible thermosensitive recording media were obtained.

(Example 12)
Example 1 (A) was carried out in the same manner as in Example 1 except that 5 parts of polyvinyl butyral having a weight average molecular weight of 75,000 was used instead of 5 parts of polyvinyl butyral having a weight average molecular weight of 100,000. 12 reversible thermosensitive recording media were obtained.

(Example 13)
Example 1 (A) was carried out in the same manner as in Example 1 except that 5 parts of polyvinyl butyral having a weight average molecular weight of 200,000 was used instead of 5 parts of polyvinyl butyral having a weight average molecular weight of 100,000. 13 reversible thermosensitive recording media were obtained.

(Comparative Example 1)
In Example 1 (A), in place of using 5 parts of polyvinyl butyral having a weight average molecular weight of 100,000, a comparative example was carried out in the same manner as in Example 1 except that 5 parts of polyvinyl butyral having a weight average molecular weight of 10,000 was used. 1 reversible thermosensitive recording medium was obtained.

(Comparative Example 2)
In Example 1 (A), in place of using 5 parts of polyvinyl butyral having a weight average molecular weight of 100,000, a comparative example was conducted in the same manner as in Example 1 except that 5 parts of polyvinyl butyral having a weight average molecular weight of 40,000 was used. 2 reversible thermosensitive recording medium was obtained.

(Comparative Example 3)
In Example 1 (A), instead of using 5 parts of polyvinyl butyral having a total unit ratio of hydroxyl group and acetate group to butyral group of 40% by mass, the total unit ratio of hydroxyl group and acetate group to butyral group is 25% by mass. A reversible thermosensitive recording medium of Comparative Example 3 was obtained in the same manner as in Example 1 except that 5 parts of certain polyvinyl butyral was used.

(Comparative Example 4)
In Example 1 (A), instead of using 5 parts of polyvinyl butyral having a total unit ratio of hydroxyl group and acetate group to butyral group of 40% by mass, the total unit ratio of hydroxyl group and acetate group to butyral group is 75% by mass. A reversible thermosensitive recording medium of Comparative Example 4 was obtained in the same manner as in Example 1 except that 5 parts of certain polyvinyl butyral was used.

(Comparative Example 5)
In Example 1 (A), instead of using 5 parts of polyvinyl butyral having a weight average molecular weight of 100,000, the same procedure as in Example 1 was conducted except that 5 parts of partially saponified polyvinyl alcohol having a weight average molecular weight of 100,000 was used. Thus, a reversible thermosensitive recording medium of Comparative Example 5 was obtained.

(Comparative Example 6)
In Example 1 (A), instead of using 5 parts of polyvinyl butyral having a weight average molecular weight of 100,000, the same procedure as in Example 1 was conducted except that 5 parts of fully saponified polyvinyl alcohol having a weight average molecular weight of 100,000 was used. Thus, a reversible thermosensitive recording medium of Comparative Example 6 was obtained.

(Comparative Example 7)
A reversible thermosensitive recording medium of Comparative Example 7 was obtained in the same manner as in Example 1 except that polyvinyl butyral was not added in Example 1 (A).

(Test 1) Color developability test Regarding the color developability evaluation method, the reversible thermosensitive recording media obtained in Examples 1 to 13 and Comparative Examples 1 to 7 were placed in a dryer at a temperature of 50 ° C and a humidity of 90% RH. After time storage, erasure printing was performed with a Star Seimitsu printer (TCP400, printing energy 0.5 mJ, erasing temperature 150 ° C.). The color density was measured using a Macbeth densitometer RD-19I. If the color density is 1.0 or more, there is no problem in actual use. The color density was evaluated according to the following criteria.

Color density ◎: 1.4 or more ○: 1.0 or more and less than 1.4 ×: Less than 1.0

(Test 2) Adhesion test Regarding the evaluation method of film strength, the reversible thermosensitive recording medium obtained in Test 1 above was stored in a dryer at a temperature of 50 ° C. and a humidity of 90% RH for 24 hours, and then the reversible thermosensitive recording. An adhesion test was performed on the surface of the medium by a grid pattern method having a width of 1 mm so as to comply with JIS K 5600-5-6. If it is 6 points or more, it is at a level where there is no problem in actual use. The film strength was evaluated according to the following criteria.

◎: 8 points or more ○: 6 points ×: 4 points or less

(Test 3) Durability Test Regarding the durability evaluation method, the reversible thermosensitive recording medium obtained in Test 1 above was stored in a dryer at a temperature of 50 ° C. and a humidity of 90% RH for 24 hours, and then the reversible thermosensitive recording. The medium was subjected to a printing test with a printer (TCP400, printing energy 0.5 mJ, erasing temperature 150 ° C.) manufactured by Star Seimitsu Co., Ltd., and then the erasing operation was repeated 100 times. The printing state after 100 times repetition and the surface state of the recording medium were visually observed and evaluated according to the following criteria.

(Double-circle): The image part was a favorable coloring state, and film peeling was not seen.
○: The image area was in a good color development state, but film peeling was slightly observed.
X: Film peeling occurred several times, and repeated tests could not be continued.

The results of Test 1 to Test 3 are shown in Table 1.

  As is apparent from the above results, the reversible thermosensitive recording layer contains at least polyvinyl butyral and an isocyanate compound as binder species, the polyvinyl butyral has a weight average molecular weight of 50,000 or more, and the butyral group of the polyvinyl butyral The total unit ratio of hydroxyl group and acetic acid group to 30 to 70% by mass allows reversible feeling with excellent film strength for good color density in erasure printing after storage for a long time in a high temperature and high humidity environment. We were able to provide a thermal recording medium.

Claims (1)

  Reversible containing a normally colorless or light dye precursor on a support and a reversible developer that forms a relatively colored state and an erased state due to differences in heating temperature and / or cooling rate after heating. In the reversible heat-sensitive recording medium having the heat-sensitive recording layer, the reversible heat-sensitive recording layer contains at least polyvinyl butyral and an isocyanate compound as binder species, and the polyvinyl butyral has a weight average molecular weight of 50,000 or more, and A reversible thermosensitive recording medium, wherein the total unit ratio of hydroxyl group and acetic acid group to butyral group of polyvinyl butyral is 30 to 70% by mass.