JP2005219409A - Reversible thermosensitive recording medium, its image processing method, printing/erasing device employing the same and displaying device and reversible thermosensitive recording label - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reversible thermosensitive recording medium, neither ply separation nor image clarity of which develops even after the repeated use of recording/erasion and which has enough endurance strength. <P>SOLUTION: A protective layer or protective layers are provided on a thermosensitive recording layer. When the protective layer is a single one, the protective layer is mainly made of an ultraviolet-curing resin or an electron ray-curing resin cross-liked with a thermal crosslinker/photocrosslinker included therein. When a plurality of protective layers are employed, the first protective layer adjoining the thermosensitive recording layer is mainly made of an ultraviolet-curing resin or an electron ray-curing resin cross-linked with a thermal crosslinker included therein under the condition that an ultraviolet absorber may be included, The second protective layer is mainly made of the ultraviolet-curing resin or the electron ray-curing resin cross-linked with the thermal crosslinker/photocrosslinker included therein. As the reversible thermosensitive recording medium, a sheet-like card, on which an information storage part (a magnetic recording layer/IC memory/optical memory or the like) and irreversible visible information (a pattern) are provided, a thermosensitive recording label attached with a self-adhesive layer or the like are employed in addition to a rolled one can be assembled in a displaying device such as an electron blackboard. <P>COPYRIGHT: (C)2005,JPO&NCIPI

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 and a method for forming and erasing the same.

  Conventionally, a heat-sensitive recording medium using a color developing reaction between an electron donating color developing compound (hereinafter also referred to as a color former) and an electron accepting compound (hereinafter also referred to as a color developer) has been widely known. With the progress of OA, it is widely used as an output paper for facsimiles, word processors, scientific measuring instruments, etc., and recently as a magnetic thermal card such as prepaid cards and point cards. However, from the viewpoint of environmental issues and recycling, use organic phosphoric acid compounds, aliphatic carboxylic acid compounds or phenolic compounds with long-chain aliphatic hydrocarbon groups as the developer, and combine this with the leuco dye that is the color former. Thus, a reversible thermosensitive coloring composition capable of repeating color development and decoloring and a reversible thermosensitive recording medium using the same in the recording layer have been proposed (for example, see Patent Document 1), and then a long chain fat. The use of a specific structure has been proposed for a phenol compound having an aromatic hydrocarbon group (see, for example, Patent Document 2).

  However, when printing and erasing are repeatedly performed under practical conditions using these media, the recording surface gradually deteriorates due to repeated force (external force due to conveyance force or platen thickness), for example, surface scraping or Film breakage and the like occurred, and as a result, a reversible thermosensitive recording medium capable of fully exhibiting the color developing / decoloring properties of the developer and color former composition has not been obtained.

In order to improve printing durability, a heat-resistant protective layer has been studied, and a thermoplastic resin or a thermosetting protective layer is used directly above the heat-sensitive recording layer or through an intermediate layer (for example, patents). However, the durability of these resins is not sufficient, and a protective layer mainly composed of a cured resin by ultraviolet rays or electron beams has been used (for example, see Patent Documents 4 and 5). .) However, as can be seen in these examples, the thermosetting method is often used for the recording layer in order to ensure adequate sensitivity and erasability, while UV-curing and electron beam curable resins are often used for the protective layer. In addition, since materials of different curing methods are used adjacent to each other, the binding at the layer interface is weak. As a result, the film is likely to be peeled off due to the external force applied by repeated printing, and structural defects occur due to the inability to cope with stress strain in the film, and the sharpness of the image decreases.
Therefore, an attempt has been made to improve the affinity with the adjacent layer by using a mixed resin of an isocyanate crosslinkable resin and an electron beam curable resin or an ultraviolet curable resin for the recording layer (see, for example, Patent Document 6). Even so, the binding was still insufficient. On the other hand, a compound that provides lubricity at a specific temperature is applied to the protective layer to reduce the stress applied to the protective layer (see, for example, Patent Document 7), but this is also insufficient.
Japanese Patent No. 2981558 Japanese Patent No. 3380277 JP-A-06-008626 Japanese Patent Application Laid-Open No. 06-344672 JP 08-011433 A JP-A-10-226167 JP 2002-248862 A

  Therefore, the present invention has been made in view of the above-mentioned problems, and is a reversible thermosensitive sensor that has sufficient strength without delamination of the medium and deterioration of image sharpness even after repeated use of recording and erasing. An object is to provide a recording medium.

That is, the object is to contain an electron donating color-forming compound and an electron accepting compound as main components on the support as described in claim 1, and the heating temperature and / or the cooling rate after heating. A reversible thermosensitive recording layer containing a reversible thermosensitive composition capable of forming a relatively colored state and a decolored state due to a difference, and at least one protective layer is provided on the reversible thermosensitive recording layer. In the reversible thermosensitive recording medium, the curing method of the uppermost layer and its adjacent layer is different, and at least one of the uppermost layer or the adjacent lower layer has functional groups that are cured by the respective curing methods simultaneously in the same molecule. It is achieved by a reversible thermosensitive recording medium characterized by containing a compound having the above.
According to invention of Claim 1, it contains an electron-donating color-forming compound and an electron-accepting compound as main components on the support, and is relatively based on the difference in heating temperature and / or cooling rate after heating. A reversible thermosensitive recording layer containing a reversible thermosensitive composition capable of forming a colored state and a decolored state, and a reversible thermosensitive recording medium provided with at least one protective layer on the reversible thermosensitive recording layer The uppermost layer and the adjacent layer have different curing methods, and at least one of the uppermost layer and the adjacent lower layer contains a compound having functional groups that are cured by the respective curing methods in the same molecule at the same time. Thus, a reversible thermosensitive recording medium having sufficient strength can be provided without causing delamination of the medium and deterioration of image sharpness even by repeated use of recording and erasing.

  According to a second aspect of the present invention, in the first aspect of the invention, the uppermost layer of the reversible thermosensitive recording medium is mainly composed of a cured ultraviolet curable resin or electron beam curable resin, and is adjacent to the uppermost layer. The layer contains a compound having simultaneously in the same molecule a functional group that reacts with heat and a functional group that reacts with light, and is cured.

  According to the second aspect of the present invention, the uppermost layer of the reversible thermosensitive recording medium is mainly composed of an ultraviolet curable resin or an electron beam curable resin, and a layer adjacent to the uppermost layer is thermally reacted. The reversible thermosensitive recording medium contains a compound having a functional group that photoreacts with a group at the same time in the same molecule and is cured. There is no reduction in the sharpness of the film, and it can have sufficient strength.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the protective layer formed on the reversible thermosensitive recording layer is formed of two layers, and the reversible thermosensitive recording layer and the adjacent first layer are adjacent to each other. One protective layer is mainly composed of a resin crosslinked by heat, and the second protective layer adjacent to the first protective layer and serving as the uppermost layer is mainly composed of a resin crosslinked by light.

  According to the third aspect of the present invention, the protective layer formed on the reversible thermosensitive recording layer is formed of two layers, and the reversible thermosensitive recording layer and the adjacent first protective layer are crosslinked by heat. The reversible thermosensitive recording medium comprises the main component of the resin, and the second protective layer adjacent to the first protective layer, which is the uppermost layer, is crosslinked with light. The adhesiveness of the protective layer can be further improved, the image sharpness of the medium can be further improved, the heat resistance can be further improved, and good repeated durability can be obtained.

  The invention according to claim 4 is the invention according to claim 3, wherein the first protective layer contains an ultraviolet shielding component.

  According to the fourth aspect of the present invention, since the first protective layer contains an ultraviolet shielding component, the image of the reversible thermosensitive recording medium has no background fogging, and can further contribute to durability. .

  The invention according to claim 5 is the invention according to claim 4, wherein the first protective layer contains an ultrafine metal oxide as an ultraviolet shielding component.

  The invention according to claim 5 can provide a reversible thermosensitive recording medium that is superior in heat resistance and contributes to durability when the first protective layer contains an ultrafine metal oxide as an ultraviolet shielding component.

  The invention according to claim 6 is the invention according to claim 5, characterized in that the ultrafine metal oxide has a primary particle diameter of 100 nm or less and a surface subjected to a hydrophobic treatment.

  According to the invention described in claim 6, the ultrafine metal oxide has a primary particle diameter of 100 nm or less and a surface subjected to a hydrophobic treatment, whereby the heat resistance of the reversible thermosensitive recording medium. Is even better and more useful for durability.

  The invention according to claim 7 is the invention according to claim 4, wherein the first protective layer contains an organic polymer having an ultraviolet absorbing structure as an ultraviolet shielding component.

  According to the seventh aspect of the present invention, the first protective layer contains an organic polymer having an ultraviolet absorbing structure as an ultraviolet shielding component, so that the uniformity of the film thickness is good and contributes to durability. A reversible thermosensitive recording medium can be provided.

  The invention according to claim 8 is characterized in that, in the invention according to any one of claims 1 to 7, the support body in which two or more kinds of sheets are bonded together is used.

  According to the invention described in claim 8, by using the support on which two or more kinds of sheets are bonded, the reversible thermosensitive recording medium has a thickness as required from about several μm to several mm. Any thickness of support can be used.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, further comprising a reversible thermosensitive recording section and an information storage section.

According to the ninth aspect of the present invention, the information stored in the information storage unit is reversibly thermoreversible by including the reversible thermosensitive recording unit and the information storage unit such as a magnetic recording layer, an IC memory, and an optical memory. By displaying on the recording unit, information can be confirmed without a special device, and the convenience of the reversible thermosensitive recording medium can be improved.
The invention according to claim 10 is the invention according to any one of claims 1 to 9, wherein irreversible visible information is previously formed on at least a part of the surface of the thermal recording surface side and / or the back surface. Features.
According to the tenth aspect of the present invention, the irreversible visible information is previously formed on at least one part of the surface and / or the back surface of the heat-sensitive recording surface, whereby a highly practical reversible heat-sensitive recording medium can be provided.
An invention according to an eleventh aspect is the invention according to any one of the first to tenth aspects, wherein the invention is processed into a card shape, a sheet shape, or a roll shape.
According to the invention described in claim 11, by processing the reversible thermosensitive recording medium into a card shape, a sheet shape or a roll shape, for example, the card-like medium can be applied to a prepaid card, a point card or a credit card. The sheet-like medium can be applied to a recording medium having a document size such as A4 size, and the roll-like medium can be applied to a recording medium such as an electronic blackboard.
The invention according to claim 12 is achieved by a printing / erasing apparatus using a reversible thermosensitive recording medium processed into a card shape or a sheet shape.
According to the twelfth aspect of the present invention, a printing medium processed into a card shape or a sheet shape, for example, a document size recording medium such as A4 size can be widely used for temporary output applications such as circulation documents and conference materials. / Erasing device can be provided.
The invention according to claim 13 is achieved by a display device having a printing / erasing section that incorporates and uses a reversible thermosensitive recording medium processed into a roll.
According to the thirteenth aspect of the present invention, it is possible to provide a display device having a printing / erasing section that incorporates and uses a reversible thermosensitive recording medium processed into a roll shape.
The invention according to claim 14 is the invention according to claim 13, wherein the display device is any one of a display board, a bulletin board, and an electronic blackboard.
According to the invention described in claim 14, since the display device does not generate dust, dust, etc., it is possible to provide a display board, a bulletin board, or an electronic blackboard that can be used in a clean room.
According to a fifteenth aspect of the present invention, an adhesive layer or a pressure-sensitive adhesive layer is provided on the side opposite to the thermal recording surface side of the support of the reversible thermosensitive recording medium according to any one of the first to eleventh aspects. This is achieved by a reversible thermosensitive recording label characterized by:
According to the fifteenth aspect of the present invention, for example, a release paper type adhesive layer or pressure-sensitive adhesive layer is provided on the side opposite to the heat-sensitive recording surface side of the support, thereby providing a base sheet such as a card or the like. A reversible thermosensitive recording label with improved practicality that can be applied to a medium can be provided.
The invention according to claim 16 is achieved by an image forming and erasing method characterized in that the reversible thermosensitive recording medium according to any one of claims 1 to 11 is subjected to image formation and / or image erasing by heating. Is done.
According to the invention described in claim 16, the reversible thermosensitive recording medium according to any one of claims 1 to 11 can be formed and / or erased by heating using a thermal head or the like. Also, it is possible to provide an image forming / erasing method capable of erasing an image by heating using at least one of a thermal head, a ceramic heater, a heat roll, a hot stamp, and a heat block.

  According to the present invention, the interlayer binding force is improved, the image sharpness and the repeated durability are excellent, and there is no delamination of the reversible thermosensitive recording medium or a decrease in the image sharpness even by repeated use of image recording / erasing. A reversible thermosensitive recording medium having sufficient strength can be provided.

  The reversible thermosensitive recording medium of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram for explaining a typical reversible thermosensitive recording medium of the present invention.
First, the reversible thermosensitive recording medium of the present invention will be explained.

  Examples of the support for the reversible thermosensitive recording medium of the present invention include paper, cellulose derivative films such as cellulose triacetate, polyolefin films such as polypropylene and polyethylene, polystyrene films or films obtained by bonding these, polyester, polycarbonate, synthetic paper, metal A foil, glass, a composite thereof, or the like is preferable, and a polyester film such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, or PET-G is preferable. Of these, polyethylene terephthalate and PET-G are preferable. In order to improve the adhesion of the coating layer, at least one surface can be subjected to surface modification by corona discharge treatment, oxidation reaction treatment (chromic acid or the like), etching treatment or the like. In order to obtain a sheet with high image clarity, polyethylene terephthalate and PET-G film having a haze of the support alone (haze defined by JIS K7105, haze) of 10% or less are particularly preferable. Moreover, the thing of the thickness as needed can also be used individually or by bonding. That is, a support having an arbitrary thickness from about several μm to about several mm is used. These supports may have a magnetic recording layer on the same surface and / or the opposite surface as the reversible thermosensitive recording layer.

  In the present invention, the compound having functional groups that are cured by the respective curing methods simultaneously in the same molecule means that it reacts with heat as a trigger, an isocyanate group that can be crosslinked by reacting with a hydroxyl group, and similarly polyamine and the like. Examples include reactive epoxy groups. In addition, in the case of using light as a trigger, an acrylate group, a methacrylate group, a vinyl group as a group that undergoes radical polymerization using a photopolymerization initiator as a catalyst, an epoxy group, an oxetane group, or a vinyl ether as a group that undergoes cationic polymerization using a cationic initiator as a catalyst. Groups and the like. Among them, a combination of a functional group of a thermal crosslinking system and a photocrosslinking system is good, and a combination of an isocyanate group and an acrylate group, an isocyanate group and a methacrylate group, an epoxy group and an acrylate group, and an epoxy group and a methacrylate group is preferable. Preference is given to a combination of isocyanate groups and acrylate groups.

  Typical examples of these include 2-methacryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, 2-hydroxy-2-oxiranylethyl acrylate, and partially acrylated bisphenol A type epoxy resin. Moreover, the compound obtained by reaction with the acrylate, methacrylate, and epoxy compound which have polyisocyanate and a hydroxyl group can also be used. In this case, in order to leave the isocyanate group, the reaction is carried out by adjusting the ratio of the hydroxyl group to be reacted with respect to the NCO value to be small. The crosslinking component can be increased.

  The ratio to be used is 98: 2 to 30:70, preferably 95: 5 to 50:50, based on the total amount of the crosslinking agent or monomer in the layer to be mixed, which will be described later. If the amount is less than this, the effect is not exhibited. On the other hand, if the amount is more than this, sufficient strength cannot be obtained even if the layers are well bonded.

  In the present invention, the curable resin used for the recording layer is, for example, a combination of a crosslinking agent and a resin having an active group that reacts with the crosslinking agent, and is a resin that can be crosslinked and cured by heat, ultraviolet rays, electron beams, or the like. By including a curable resin in the recording layer, the heat resistance and coating strength of the recording layer are improved, and the repeated durability of the reversible thermosensitive recording medium is improved.

  Resins used for thermosetting have groups that react with crosslinking agents such as hydroxyl groups and carboxyl groups, such as phenoxy resins, polyvinyl butyral resins, cellulose acetate propionate, cellulose acetate butyrate, acrylic polyols, polyester polyols, polyurethane polyols, etc. There are resins or resins obtained by copolymerizing monomers having a hydroxyl group or a carboxyl group and other monomers. Among them, acrylic polyol resin, polyester polyol resin, and polyurethane polyol resin are preferable, and when the hydroxyl value is 70 (KOHmg / g) or more, durability, coating film surface hardness, and crack resistance are improved. Especially preferably, it is 90 (KOHmg / g) or more. The magnitude of the hydroxyl value affects the crosslink density, and therefore affects the chemical resistance and physical properties of the coating film.

  Acrylic polyol resins have different characteristics depending on the structure, and hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), 2-hydroxyethyl methacrylate (HEMA), 2-hydroxypropyl methacrylate (HPMA) as hydroxyl monomers. , 2-hydroxybutyl monoacrylate (2-HBA), 1,4-hydroxybutyl monoacrylate (1-HBA), etc. are used. 2-hydroxyethyl methacrylate is preferably used because of its good properties and durability.

  Examples of the thermal crosslinking crosslinking agent include isocyanates, amino resins, phenol resins, amines, and epoxy compounds. Of these, isocyanates are preferable, and polyisocyanate compounds having a plurality of isocyanate groups are particularly preferable. Specific examples of the compound are hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), and xylylene diisocyanate. (XDI) or the like, or those having a structure converted to adduct type, burette type, or isocyanurate type obtained by combining these with trimethylolpropane or the like, and blocked isocyanates can be mentioned. Among them, as the compound species, a non-yellowing type in which a hetero atom is not substituted on the aromatic ring, particularly HDI, IPDI, and XDI are preferable, and the HDI type is particularly preferable. The structure type is particularly preferably an adduct type or an isocyanurate type.

  As the amount of the crosslinking agent added to the resin, the ratio of the functional group of the crosslinking agent to the number of active groups contained in the resin is preferably 0.01 to 2 as a whole, and the thermal strength is insufficient below this. In addition, adding more than this adversely affects the color developing / decoloring properties.

  Furthermore, you may use the catalyst used for this kind of reaction as a crosslinking accelerator. Examples of the crosslinking accelerator include tertiary amines such as 1,4-diazabicyclo [2,2,2] octane, and metal compounds such as organotin compounds.

  Further, as the recording layer resin, an epoxy resin that crosslinks with an amine curing agent by heat can also be used. Various known materials can be used as this combination. For example, the epoxy resin main component is usually obtained by reacting epichlorohydrin with a diol component such as bisphenol A type, bisphenol F type, or bisphenol Z type as a skeleton. In addition to these epoxy resins, modified epoxy resins such as urethane-modified epoxy resins, rubber-modified epoxy resins and chelate-modified epoxy resins can also be used. Examples of the amine curing agent include aliphatic polyamines, alicyclic polyamines, aromatic polyamines, polyamide amines, dicyandiamide and the like.

  As the resin used in the ultraviolet ray and electron beam curing, various known polymerizable monomers described in the section of the protective layer can be used.

  In addition to the curing system, various known copolymer resins can also be used, for example, vinyl chloride-based, acrylic-based, styrene-based resins, specifically vinyl chloride-vinyl acetate-vinyl alcohol copolymers, Examples include vinyl chloride-vinyl acetate-hydroxypropyl acrylate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, and the like.

  The electron-donating color-forming compound used in the present invention is a leuco dye, and is applied alone or in combination of two or more. However, it is a colorless or light-colored dye precursor, and is not particularly limited. For example, triphenylmethanephthalide, triallylmethane, fluoran, phenothiocyan, thioferolane, xanthene, indophthalyl, spiropyran, azaphthalide, chromenopyrazole, methine, rhodamine anilino A leuco compound such as a lactam, rhodamine lactam, quinazoline, diazaxanthene, or bislactone is preferably used. Among these, fluorane-based and phthalide-based leuco dyes are particularly preferable in terms of color development / decoloration characteristics, color, storage stability, and the like, more preferably 3-diethylamino-6-methyl-7-anilinofluorane, 3- (N-ethyl-Np-toluidino) amino-6-methyl-7-anilinofluorane, 3-di (n-butylamino) -6-methyl-7-anilinofluorane, 3-n-methyl Black-colored leuco dyes such as N-propylamino-6-methyl-7-anilinofluorane, 3-diethylamino-7,8-benzofluorane, 3- (N-ethyl-N-isoamyl) -7 , 8-benzofluorane, 1,3-dimethyl-6-diethylaminofluorane, 1,3-dimethyl-6-di-n-butylaminofluorane, 3-diethylamino-7-methylfluora , Red chromogenic leuco dyes such as 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide, crystal violet lactone, 3- (4-diethylamino-2-ethoxyphenyl) -3 Blue coloring systems such as-(1-ethyl-2-methylindol-1-yl) -4-azaphthalide and 3- (4-diethylaminophenyl) -3- (1-ethyl-2-indol-3-yl) phthalide Leuco dyes, 10-diethylamino-2-ethylbenzo [1,4] thiazino [3,2-b] fluorane, 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 3 , 3-Bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide, 3- [2,2-bis (1-ethyl-2-methyl-3-indolyl) vinyl]- - (4-diethylamino-phenyl) phthalide, 3- [1,1-bis (4-diethylamino-phenyl) ethylene-2-yl] -6-dimethylamino phthalide leuco dye having absorption in the infrared region, such as de. Among them, 2-anilino-3-methyl-6-disubstituted aminofluoranes such as 2-anilino-3-methyl-6-diethylaminofluorane and 2-anilino-3-methyl-6-di (n-butylamino) fluorane Crystal violet lactone and 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-1-yl) -4-azaphthalide are preferable from the viewpoints of color tone and color-decoloring properties. . These may be used alone or mixed, and can be multicolored or full-colored by laminating layers that develop colors of different colors.

  Further, the electron-accepting compound used in the present invention is not limited as long as it can reversibly develop and decolorize by using heat as a factor, and has a structure having a color developing ability to develop a color former in the molecule, for example, It is a compound having at least one structure in which a phenolic hydroxyl group, a carboxylic acid group, a phosphoric acid group, and the like are connected to a structure that controls cohesion between molecules, for example, a long-chain hydrocarbon group. The linking moiety may be via a divalent or higher valent linking group containing a hetero atom, and the same linking group and / or aromatic group may also be included in the long-chain hydrocarbon group. In particular, it is preferable to use a phenol compound represented by the following general formula (1).

（式中、ｎは１乃至３の整数を示し、ＸはＮ原子又はＯ原子を含む２価の基を表わす。また、Ｒ１は置換基を有していてもよい炭素数２以上の脂肪族炭化水素基を表わし、Ｒ２は炭素数１以上１４以下の脂肪族炭化水素基を表わす）
一般式（１）において、脂肪族炭化水素基は直鎖でも分枝していてもよく、不飽和結合を有していてもよい。炭化水素基につく置換基としては、水酸基、ハロゲン原子、アルコキシ基等がある。Ｒ１、Ｒ２の炭素の和が７以下では発色の安定性や消色性が低下するため、炭素数は８以上が好ましく、１１以上であることが更に好ましい。また、Ｘ基はＮ原子又はＯ原子を含む２価の基であるが、特に好ましくはアミド基及び尿素基であり、更に好ましくは尿素基である。Ｒ１は炭素数２以上の脂肪族炭化水素基を表わすが、特に好ましくは炭素数５以上の脂肪族炭化水素基であり、更に好ましくは炭素数１０以上の脂肪族炭化水素基である。Ｒ２の炭素数は１以上１４以下であるが、特に好ましくはＲ２の炭素数が８以上１４以下である。１種又は２種以上を混合して用いてもよい。

(In the formula, n represents an integer of 1 to 3, X represents a divalent group containing an N atom or an O atom, and R1 is an aliphatic having 2 or more carbon atoms which may have a substituent. Represents a hydrocarbon group, and R2 represents an aliphatic hydrocarbon group having 1 to 14 carbon atoms)
In the general formula (1), the aliphatic hydrocarbon group may be linear or branched, and may have an unsaturated bond. Examples of the substituent attached to the hydrocarbon group include a hydroxyl group, a halogen atom, and an alkoxy group. When the sum of carbons of R1 and R2 is 7 or less, the stability of color development and decoloring properties are lowered. The X group is a divalent group containing an N atom or an O atom, particularly preferably an amide group and a urea group, and more preferably a urea group. R1 represents an aliphatic hydrocarbon group having 2 or more carbon atoms, particularly preferably an aliphatic hydrocarbon group having 5 or more carbon atoms, and more preferably an aliphatic hydrocarbon group having 10 or more carbon atoms. R2 has 1 to 14 carbon atoms, and particularly preferably R2 has 8 to 14 carbon atoms. You may use 1 type or in mixture of 2 or more types.

  Further, by using together the developer having the above-described characteristics and a compound having at least one —NHCO— group or —OCONH— group in the molecule as a decoloring accelerator, the color disappearing in the process of forming a decoloring state. Intermolecular interaction is induced between the color accelerator and the developer, and the color development and decoloring characteristics are improved. Among these, compounds represented by the general formulas (2) to (8) are preferable.

（式中Ｒ１，Ｒ２、Ｒ４は炭素数７以上２２以下の直鎖アルキル基、分枝アルキル基、不飽和アルキル基を表し、Ｒ３は炭素数１乃至１０の２価の官能基、Ｒ５は炭素数４〜１０の３価の官能基を表す）
本発明の可逆性感熱記録媒体には、必要に応じて記録層の塗布特性や発色消色特性を改善、又は制御するための添加剤を用いることができる。これらの添加剤には、例えば界面活性剤、導電剤、充填剤、酸化防止剤、光安定化剤、発色安定化剤、消色促進剤などがある。

(Wherein R1, R2, and R4 represent a straight chain alkyl group, branched alkyl group, or unsaturated alkyl group having 7 to 22 carbon atoms, R3 is a divalent functional group having 1 to 10 carbon atoms, and R5 is carbon. Represents a trivalent functional group of several 4 to 10)
In the reversible thermosensitive recording medium of the present invention, an additive for improving or controlling the recording layer coating characteristics and color developing / decoloring characteristics can be used as necessary. These additives include, for example, surfactants, conductive agents, fillers, antioxidants, light stabilizers, color development stabilizers, and decolorization accelerators.

  The appropriate ratio of the color former to the color developer varies depending on the combination of the compounds to be used, but the developer is generally in the range of 0.1 to 20 with respect to the color developer 1 at a molar ratio, preferably 0. The range is from 2 to 10. If the amount of the developer is less or more than this range, the density of the colored state is lowered, which causes a problem. Further, when a decoloring accelerator is added, the proportion thereof is preferably 0.1 to 300% by weight, more preferably 3 to 100% by weight with respect to the developer. In addition, the color former and the developer can be used in a microcapsule. The ratio of the color developing component to the resin in the reversible thermosensitive recording layer is preferably 0.1 to 10 with respect to the color developing component 1, and if the amount is less than this, the heat intensity of the reversible thermosensitive recording layer is insufficient, and the ratio is higher. Is problematic because the color density is lowered.

  For the formation of the recording layer, a coating solution prepared by uniformly mixing and dispersing the above-described developer, color former, various additives, curing agent, crosslinked resin and coating solvent is used.

  Solvents used for preparing the coating liquid include water, alcohol, ketone, amide, ether, glycols, glycol ethers, glycol ester acetates, esters, aromatic hydrocarbons, aliphatic hydrocarbons, halogenated carbonization. Examples thereof include hydrogens, sulfoxides, and pyrrolidones. Among these, water, methanol, ethanol, isopropanol, n-butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, N, N-dimethylformamide, N, N-dimethylacetamide, tetrahydrofuran, 1,4-dioxane, 3,4 -Dihydro-2H-pyran, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, methyl acetate, ethyl acetate, butyl acetate, toluene, xylene, hexane, heptane, cyclohexane, dimethyl sulfoxide, etc. are often used. Preferred are aprotic solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, tetrahydrofuran, ethyl acetate, butyl acetate, toluene and xylene.

  The coating liquid can be prepared using a known coating liquid dispersing apparatus such as a paint shaker, a ball mill, an attritor, a three-roll mill, a keddy mill, a sand mill, a dyno mill, or a colloid mill. In addition, these materials may be dispersed in a solvent using these coating liquid dispersing apparatuses, or may be dispersed and mixed in a solvent alone. Further, it may be dissolved by heating and deposited by rapid cooling or cooling.

  The thickness of the thermosensitive recording layer is preferably in the range of 1 to 20 μm, more preferably 3 to 15 μm.

  Next, the protective layer in the reversible thermosensitive recording medium of the present invention will be described. As can be seen from FIG. 1, the protective layer here means the second uppermost protective layer, and as will be described in detail later, the reversible thermosensitive recording medium of the present invention has a space between the protective layer and the thermosensitive recording layer. Is provided with a first protective layer.

  The protective layer in the present invention, the so-called second protective layer, is mainly composed of a resin that is cured by ultraviolet rays or electron beams. Examples of monomers before curing include glycidyl acrylate, glycidyl methacrylate, diglycidyl ether diacrylate of 1,6-hexanediol, urethane acrylate, urethane methacrylate, epoxy acrylate, epoxy methacrylate, tetrahydrofurfuryl acrylate. , Tetrahydrofurfuryl methacrylate, caprolactone-modified tetrahydrofurfuryl acrylate, neopentyl glycol-modified trimethylolpropane diacrylate, pentamethylpiperidyl methacrylate, diacrylated isocyanurate, tris (acryloxyethyl) isocyanurate, caprolactone-modified tris (acryloxyethyl) Isocyanurate, tris (methacryloxyethyl) isocyanate Rate, N- acryloyl morpholine, N- vinylpyrrolidone. Cationic polymerization systems include alicyclic epoxy compounds, epoxidized polybutadiene, styrene oxide, oxetanes, and vinyl ethers. Of these, a radical polymerization system is preferable, and in particular, urethane acrylate, epoxy acrylate, polyester acrylate, and polyether acrylate are preferable.

  In the present invention, in order to improve the function of the protective layer resin, it can be mixed with a plurality of monomers and oligomers. Particularly preferred are polymerizable polyfunctional monomers and oligomers having 4 or more functional groups.

  Examples of polymerizable polyfunctional monomers and oligomers are trimethylolpropane triacrylate, pentaerythritol triacrylate, glycerin PO-added triacrylate, trisacryloyloxyethyl phosphate, pentaerythritol tetraacrylate, trimethylolpropane propylene oxide 3 mol adduct Triacrylate, glyceryl propoxy triacrylate, dipentaerythritol polyacrylate, polyacrylate of dipentaerythritol caprolactone adduct, propionic acid / dipentaerythritol triacrylate, hydroxypivalaldehyde-modified dimethylolpropyne triacrylate, propionic acid・ Dipentaerythritol tetraacrylate, ditrimethylolpro Down tetraacrylate, pentaacrylate of dipentaerythritol propionate, trimethylolpropane triacrylate added urethane prepolymer, dipentaerythritol hexaacrylate (DPHA), .epsilon.-caprolactone adducts of DPHA structure thereof.

  Among these, a polymerizable polyfunctional monomer is preferably used from the viewpoint of heat resistance and mechanical strength, and dipentaerythritol hexaacrylate, pentaerythritol tetraacrylate, and a mixture of these and urethane acrylate are preferable.

  Furthermore, the use of a polymerizable monomer having a silicone moiety such as polysiloxane improves surface lubricity and durability. The addition amount at this time is preferably 0.05 to 50% by weight with respect to the total weight of the resin component of the protective layer. If it is less than 0.05%, almost no effect is exhibited. Conversely, if it exceeds 50%, the film becomes too flexible and the durability is lost. Particularly preferred is 0.1 to 30%.

  Other fillers may be added to the protective layer to provide functions such as surface roughening and printability. Examples of inorganic fillers include carbonates such as calcium carbonate and magnesium carbonate, phosphates such as calcium phosphate, anhydrous silicic acid, hydrous silicic acid, hydrous aluminum silicate, hydrous calcium silicate and the like; alumina, zinc oxide, Examples thereof include oxides such as iron oxide and calcium oxide; hydroxides such as aluminum hydroxide. Organic fillers include silicone resin, cellulose resin, epoxy resin, nylon resin, phenol resin, polyurethane resin, urea resin, melamine resin, polyester resin, polycarbonate resin, styrene, polystyrene, polystyrene / isoprene, styrene vinylbenzene Examples thereof include resins, acrylic resins such as vinylidene chloride acrylic, acrylic urethane, and ethylene acrylic, polyethylene resins, formaldehyde resins such as benzoguanamine formaldehyde, melamine formaldehyde, polymethyl methacrylate resins, and vinyl chloride resins.

  Among them, it is preferable to use metal oxide fine particles surface-treated with organosilane. The organosilane treatment can be performed alone before preparing the coating solution, or can be performed by mixing a silane coupling agent after dispersion in the coating solution. Various conventionally known silane coupling agents can be used. Various silicone oils such as trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, trimethylalkoxysilane, dimethyldialkoxysilane, methyltrialkoxysilane, hexamethyldisilazane, alkylsilane coupling agents, vinyltriethoxysilane, vinyltrichlorosilane, Vinylsilane compounds such as vinyltrimethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane , Γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane and other epoxy silane compounds, γ-aminopropyl Liethoxysilane, γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-phenylamino Aminosilane compounds such as propyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxy Examples include reactive silane compounds such as silane and ureidopropyltriethoxysilane. Among these, a vinyl silane compound, an epoxy silane compound, an amino silane compound, and a reactive silane compound are particularly preferable because the denseness and toughness of the layer are improved, and the reactive silane compound is most preferable.

  The protective layer of the present invention, the so-called second protective layer, is crosslinked and cured by heat, ultraviolet rays, electron beams, or a combination thereof. However, in the thermal crosslinking that requires a certain high temperature and time, the recording layer is colored, so that the temperature cannot be increased too much, and as a result, the coating strength as the protective layer may be insufficient. In addition, crosslinking strength by electron beam can provide sufficient coating strength in a short time, but the electron beam irradiation device and the electron beam curing resin are expensive, and the inert gas replacement is required and the running cost is high. From the standpoint, cross-linking curing with ultraviolet rays is preferable. In the case of curing using ultraviolet rays, a photopolymerization initiator and a photopolymerization accelerator are used. The photopolymerization initiator used in the present invention can be broadly classified into a radical reaction type and an ion reaction type, and the radical reaction type is further classified into a photocleavage type and a hydrogen abstraction type. Examples of photopolymerization initiators include isobutyl benzoin ether, isopropyl benzoin ether, benzoin ethyl ether benzoin methyl ether, 1-phenyl-1,2-propanedione-2- (o-ethoxycycarbonyl) oxime, 2,2- Dimethoxy-2-phenylacetophenone benzyl, hydroxycyclohexyl phenyl ketone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzophenone, chlorothioxanthone, 2-chlorothioxanthone, isopropylthioxanthone, 2-methyl Examples thereof include thioxanthone and chlorine-substituted benzophenone, and are used alone or as a mixture of two or more thereof, but are not limited thereto.

  The photopolymerization accelerator used in the present invention has an effect of improving the curing rate with respect to a hydrogen abstraction type photopolymerization initiator such as benzophenone or thioxanthone. There are tertiary amines and aliphatic amines. Specific examples include p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, and the like. These photopolymerization accelerators are used alone or in combination of two or more. The addition amount of these photopolymerization initiator and photopolymerization accelerator is preferably 0.1 to 20% by weight, more preferably 1 to 10% by weight, based on the total weight of the resin component of the protective layer.

  The dynamic friction coefficient on the surface of the reversible thermosensitive recording medium is preferably 0.3 or less in order to eliminate image deterioration due to mechanical damage even when printing and erasing are repeated. When the dynamic friction coefficient is larger than 0.3, the slipperiness of the medium surface is lowered and a conveyance failure occurs.

  In order to achieve this dynamic friction coefficient of 0.3 or less, silicone having a polymerizable group, silicone grafted polymer, wax, mold release agent such as zinc stearate, and lubricant such as silicone oil can be added. The amount of these added is preferably 0.01 to 50% by weight, more preferably 0.1 to 40% by weight, based on the total weight of the resin component of the protective layer. Even if the addition amount is small, the effect is exhibited, but if it exceeds 50% by weight, there may be a problem in adhesion to the lower layer.

  Further, an organic ultraviolet absorber may be contained in the protective layer, and the content thereof is preferably in the range of 0.5 to 10% by weight with respect to the total weight of the resin component of the protective layer. Furthermore, conventionally known surfactants, antioxidants, leveling agents, light stabilizers, antistatic agents and the like may be contained as additives.

  Further, the surface roughness Ra of the medium surface is preferably 0.2 μm or less. If the surface roughness Ra exceeds 0.2 μm, sufficient glossiness cannot be obtained, and gloss change occurs due to repeated use, or erase marks are recognized. And there is a case where an illusion that the remaining erasure is increased.

  The dynamic friction coefficient is measured using a ceramic ball with a HEIDON type tester. At that time, the load is 200 g, and the moving speed is 0.75 mm / s. The surface roughness Rz is measured based on the JIS B0601 method, and Ra represents the center line average roughness of the surface to be measured. The surface roughness Ra is measured using, for example, a surface roughness shape measuring device Surfcom 570A. The conditions at that time are a cutoff value of 0.8 mm, a measurement length of 2.5 mm, a scanning speed of 0.3 mm / s, and a stylus curvature. The radius is 5 μm.

  The thickness of the protective layer is preferably in the range of 0.1 to 20 μm, more preferably 0.5 to 10 μm, and even more preferably 1.5 to 6 μm.

  In the present invention, as an intermediate layer between the two for the purpose of improving the adhesion between the recording layer and the protective layer, preventing alteration of the recording layer by applying the protective layer, and preventing the additives in the protective layer from being transferred to the recording layer. It is preferable to provide a first protective layer, which can improve the image clarity of the medium. Further, by using a curable resin for the first protective layer, the heat resistance of the reversible thermosensitive recording medium is further improved, and better repeated durability can be obtained. Therefore, as already described, the protective layer located at the uppermost layer described above is also referred to as a second protective layer in the present invention.

  The first protective layer is mainly made of a resin, and the thermosetting resin used in the recording layer can be used as the resin used for the first protective layer. Moreover, it is preferable to contain a ultraviolet absorber. Examples of the ultraviolet absorber used include benzotriazole-based, benzophenone-based, salicylic acid ester-based, cyanoacrylate-based, and cinnamic acid-based UV absorbers, preferably benzotriazole-based organic compounds. Of these, those in which the hydroxyl group is protected by an adjacent bulky functional group are particularly preferred, and 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole, 2- (2′-hydroxy) is particularly preferred. -3′-t-butyl-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2 ′ -Hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole is preferred. Further, a polymer having polymer structure such as acrylic resin, styrene resin, caprolactone, or the like may be pendant with a skeleton having such ultraviolet absorbing ability. The content of these ultraviolet absorbers is preferably in the range of 0.5 to 50% by weight based on the total weight of the resin component of the first protective layer.

  Examples of the inorganic compound include metal oxide fine particles having an average particle size of 100 nm or less. For example, zinc oxide, indium oxide, alumina, silica, zirconia, tin oxide, cerium oxide, iron oxide, antimony oxide, barium oxide, calcium oxide. , Metal oxides such as barium oxide, bismuth oxide, nickel oxide, magnesium oxide, chromium oxide, manganese oxide, tantalum oxide, niobium oxide, thorium oxide, hafnium oxide, molybdenum oxide, and composite oxides thereof. Silica, alumina, zinc oxide, titanium oxide and cerium oxide are preferred. The surface can be pretreated with silicone, wax, organosilane coupling agent, titanate coupling agent, silica, or the like, or the surface can be modified by mixing the coupling agent after adjusting the coating solution. The content of these inorganic ultraviolet shielding agents is preferably in the range of 1 to 95% in terms of volume fraction. Further, these organic and inorganic ultraviolet shielding agents may be contained in the recording layer.

  As a method for producing a filler having an average particle size of 100 nm or less, it can be prepared using a conventional technique such as a gas phase reaction method or a liquid phase reaction method. The particle size is measured by laser diffraction method or Coulter counter, so the aggregate particle size is measured, so the image is captured with an electron microscope such as a transmission electron microscope or a scanning electron microscope, and image analysis by a computer or manual histogram is performed. It is performed by a method of calculating the primary particle diameter by creation.

  The thickness of the first protective layer is preferably in the range of 0.1 to 20 μm, more preferably 0.5 to 5 μm. The solvent used for the coating liquid of the first protective layer and the dispersion apparatus for the coating liquid may be a known method used for the second protective layer.

  In the present invention, in order to effectively use the applied heat, a heat-insulating undercoat layer can be provided between the support and the heat-sensitive recording layer. The undercoat layer can be formed by coating using a binder resin containing organic or inorganic fine hollow particles or porous particles. An undercoat layer may be provided for the purpose of improving the adhesion between the support and the heat-sensitive recording layer and preventing penetration of the heat-sensitive recording layer material into the support.

  For the undercoat layer, a resin similar to the resin for the heat-sensitive recording layer or the protective layer can be used. The heat-sensitive recording layer and the undercoat layer can contain inorganic fillers such as calcium carbonate, magnesium carbonate, titanium oxide, silicon oxide, aluminum hydroxide, kaolin, and talc and / or various organic fillers. In addition, a lubricant, a surfactant, a dispersant, and the like can be contained.

  There are no particular restrictions on the coating method for providing the recording layer, the first and second protective layers, and the undercoat layer. The substrate is continuously rolled or cut into a sheet, blade coating, wire It is applied by a known method such as bar coating, spray coating, air knife coating, bead coating, curtain coating, gravure coating, kiss coating, reverse roll coating, dip coating, and die coating. The coated sheet is subsequently conveyed into a blower dryer and dried at 30 to 150 ° C. for 10 seconds to 10 minutes.

In particular, for defect-free coating, the coating solution is not only normal filter paper in advance or during feeding, but also a mesh such as stainless mesh, nylon mesh, natural or synthetic fiber filter such as cotton filter, fiber carbon filter, By passing through a membrane filter such as a membrane filter or applying ultrasonic waves for 1 minute to 200 hours, preferably 10 minutes to 80 hours, foreign matters can be removed, bubbles can be mixed, and dispersion can be avoided. Moreover, it is preferable to apply all layers consistently in a clean room of class 10,000 or less. For drying, it is preferable to heat an inert gas such as nitrogen or air that has passed through a filter and a dehumidifier, and spray this from the front surface, the back surface, or both. Among these, filtration by a cotton filter or a membrane filter or ultrasonic irradiation is particularly preferable. By appropriately selecting and using the apparatus as described above, the uniformity of the coating layer is improved, and the number of pinhole-shaped print defects per 1 m ² can be reduced to 100 or less.

  In the case of thermosetting, the recording layer and the protective layer are cured as necessary after coating and drying. By curing, in the case of thermal crosslinking, crosslinking can be promoted, and in other cases, the residual solvent can be reduced to stabilize the quality. A thermostatic bath or the like may be used for a relatively short time at a relatively high temperature, or a heat treatment may be performed at a relatively low temperature for a long time. The curing condition is preferably about 1 to 200 hours under a temperature condition of about 10 to 130 ° C. More preferably, heating is performed at a temperature of 15 to 100 ° C. for about 2 minutes to 180 hours. In production, since productivity is emphasized, it is difficult to take time until the crosslinking is sufficiently completed. Therefore, it is preferable to heat at a temperature of 40 to 100 ° C. for about 2 minutes to 120 hours. The hot air may be directly applied to the application surface, or may be left in a thermostatic bath in a state of being cut into a roll shape or a sheet shape. When it is not desired to apply temperature, a vacuum drying method may be used. The physical properties can be controlled or the production process can be made more efficient by increasing or decreasing the temperature stepwise, or by dividing into multiple times such as after coating the upper layer or simply dividing the time.

The film formation by ultraviolet rays is performed by applying a photopolymerization reaction with an ultraviolet irradiation device after coating and drying. A conventionally known irradiation apparatus can be used for ultraviolet curing, and the light source includes a mercury lamp, a metal halide lamp, a gallium lamp, a mercury xenon lamp, a flash lamp, etc., and the photopolymerization initiator and the photopolymerization accelerator described above can be used. A light source having an emission spectrum corresponding to the ultraviolet absorption wavelength may be used. Further, as the irradiation conditions, the lamp output and the conveyance speed may be determined according to the irradiation energy necessary for crosslinking the resin. In addition, when performing cross-linking curing with an electron beam, the electron beam irradiation device may be selected from a scanning type and a non-scanning type depending on the purpose such as irradiation area and irradiation dose. What is necessary is just to determine an electric current, irradiation width, and a conveyance speed according to the dose required for bridge | crosslinking.
Thereby, the present invention contains an electron-donating color-forming compound and an electron-accepting compound as main components on the support, and a relatively colored state due to a difference in heating temperature and / or cooling rate after heating. In a reversible thermosensitive recording layer comprising a reversible thermosensitive composition capable of forming a decolored state and a reversible thermosensitive recording medium comprising at least one protective layer on the reversible thermosensitive recording layer, the uppermost layer And the curing method of the adjacent layer is different, and at least one of the uppermost layer or the adjacent lower layer contains a compound having simultaneously functional groups that are cured by the respective curing methods in the same molecule. The reversible thermosensitive recording medium can be provided.
In addition, the present invention is mainly composed of an ultraviolet curable resin or an electron beam curable resin in which the uppermost layer of the reversible thermosensitive recording medium is cured, and a layer adjacent to the uppermost layer has a photoreactive functional group. It is possible to provide a reversible recording medium comprising a compound having a group simultaneously in the same molecule and cured.
Further, in the present invention, the protective layer formed on the reversible thermosensitive recording layer is formed from two layers, and the main component is a resin in which the reversible thermosensitive recording layer and the adjacent first protective layer are crosslinked by heat, It is possible to provide a reversible thermosensitive recording medium characterized in that the second protective layer adjacent to the first protective layer, which is the uppermost layer, is mainly composed of a resin crosslinked by light.

  Furthermore, the present invention can provide a reversible thermosensitive recording medium characterized in that the first protective layer contains an ultraviolet shielding component.

  In addition, the present invention can provide a reversible thermosensitive recording medium in which the first protective layer contains an ultrafine metal oxide as an ultraviolet shielding component.

  Furthermore, the present invention can provide a reversible thermosensitive recording medium characterized in that the ultrafine metal oxide has a primary particle size of 100 nm or less and the surface is subjected to a hydrophobic treatment.

  In addition, the present invention can provide a reversible thermosensitive recording medium characterized in that the first protective layer contains an organic polymer having an ultraviolet absorbing structure as an ultraviolet shielding component.

  Furthermore, the present invention can provide a reversible thermosensitive recording medium characterized in that a support on which two or more sheets are bonded is used.

Next, modifications of the reversible thermosensitive recording medium of the present invention will be described.
In recent years, disc cartridges incorporating thick cards such as IC cards and optical cards, thin sheets such as non-contact IC tags, flexible disks, magneto-optical recording disks (MD), and disks that can rewrite storage information such as DVD-RAM. , CD-RW discs that do not use disc cartridges, CD-R discs, write-once discs, optical information recording media (CD-RW) using phase change storage materials, video tape cassettes, etc. From the surface of the support constituting the reversible thermosensitive recording medium, on the surface opposite to the surface on which the thermosensitive recording layer is formed, an adhesive layer or an adhesive layer is provided to form a thermosensitive recording label as a base sheet such as a card or other You may affix on a medium. At this time, there are an adhesive layer or a pressure-sensitive adhesive layer (non-peeling paper type) and an adhesive layer or pressure-sensitive adhesive layer with a release paper (peeling paper type). As a material constituting the material, a hot melt type material is usually used.

  Commonly used materials can be used for the adhesive layer or the pressure-sensitive adhesive layer. For example, urea resin, melamine resin, phenol resin, epoxy resin, vinyl acetate resin, vinyl acetate-acrylic copolymer, ethylene-vinyl acetate copolymer, acrylic resin, polyvinyl ether resin, vinyl chloride-vinyl acetate Copolymer, polystyrene resin, polyester resin, polyurethane resin, polyamide resin, chlorinated polyolefin resin, polyvinyl butyral resin, acrylic ester copolymer, methacrylic ester copolymer, natural rubber , Cyanoacrylate resins, silicon resins, and the like, but are not limited thereto.

  As the base sheet used in the present invention, a sheet made of the following materials or a laminate thereof is used.

  Chlorine-containing polymer: polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride-acrylate copolymer, Polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer, etc., polyester resin: polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), or acid components such as terephthalic acid or isophthalic acid Biodegradable plastic resins such as condensation ester resins (for example, PETG: trademark of Eastman Chemical Co.) with alcohol components such as ethylene glycol or cyclohexanedimethanol: Polylactic acid resin, starch and modified polyvinyl alcohol Natural polymer system comprising a Lumpur such as a resin, microbial production resin consisting of β- hydroxybutyrate and β- hydroxyvaleric acid. Further examples include synthetic resin sheets or synthetic papers such as polyacetate, polystyrene (PS), epoxy resin, polyvinyl chloride (PVC) and polycarbonate (PC), polyamide resin, acrylic resin, and silicone resin. They may be combined or may be a laminate of these materials.

  As an example of such lamination, for example, a core sheet in which two white polyvinyl chloride resin sheets having a thickness of 250 μm are laminated, and a transparent polyvinyl chloride resin sheet having a thickness of 100 μm on the front and back surfaces of the core sheet are used as oversheets. For example, a laminated sheet, for example, a core sheet in which two white PETG sheets with a thickness of 250 μm are laminated, and a transparent PETG with a thickness of 100 μm laminated as an oversheet on the front and back surfaces of the core sheet, and the like.

As a method for attaching the base sheet and the thermosensitive recording label, as shown in FIGS. 2 and 3, both are placed so as to face the mirror plate and sandwiched between the two mirror plates, and thermocompression bonding is performed. There is a way to do it. Thermocompression bonding, using known means, such as heat press, typically 5 to 70 kg / cm ^2, preferably under pressure of 10 to 50 kg / cm ^2, 80 to 170 ° C., preferably in the range of from 90 to 0.99 ° C. Done in The heating temperature at the time of thermocompression bonding is determined by selecting an optimum temperature range depending on the base sheet. Further, the heat-sensitive recording label and the base sheet can be heat-bonded after heat-bonding in advance. The thermal bonding may be performed by pressing a rubber roll or the like. Then, thermobonding is completed by heat bonding. The thermal bonding is usually performed in a temperature range of 90 to 130 ° C. Such thermocompression bonding can be performed under the above-described conditions, for example, in a state of being held for less than 1 hour, preferably about 1 to 50 minutes. The holding time is merely an example, and is not particularly limited in the present invention.

  Here, for example, when a thermal recording label provided with a protective layer whose surface has been roughened with a filler is thermocompression bonded onto a substrate sheet such as a card, the filler on the surface of the protective layer is pushed into the protective layer or the lower layer by thermocompression bonding. The surface gloss increases, and as a result, the effect of the filler disappears and the durability of the cycle decreases.If printing and erasing are repeated while the surface gloss is increased, the gloss of the printed / erased portion decreases and the There may be a new problem that a difference in glossiness from the print / erase part is recognized as gloss unevenness. However, the use of the protective layer of the present invention can also solve the above problem. It is preferable that the surface roughness Ra of the reversible thermosensitive recording medium at this time is 0.15 μm or less because further glossiness can be obtained.

  For example, when a laminate such as a transparent polyvinyl chloride sheet / white polyvinyl chloride sheet / white polyvinyl chloride sheet / transparent polyvinyl chloride sheet is used as the base sheet, the heating temperature during the thermocompression bonding is as follows: About 130-150 degreeC is preferable, and the heating temperature at the time of using laminated body like transparent PETG / white PETG / white PETG / transparent PETG may be about 100-130 degreeC.

  Such thermocompression bonding may be performed by other means, but the pressure and temperature conditions at that time are performed in the same manner as described above.

  In the reversible thermosensitive recording medium of the present invention, the thermosensitive recording label may be provided on the entire surface of the base sheet, may be provided on a part thereof, or provided on one or both sides of the base sheet. It is often selected as appropriate. When a thermosensitive recording label is attached by thermocompression bonding, an adhesive layer or a pressure-sensitive adhesive layer is not necessarily required on the surface opposite to the surface on which the thermosensitive recording layer of the support constituting the reversible thermosensitive recording medium is formed.

  The reversible thermosensitive recording medium of the present invention provides both a thermoreversible recording unit and an information storage unit, and displays information stored in the information storage unit on the thermoreversible recording unit. Information can be confirmed even without it, improving convenience. A magnetic recording layer, an IC recording unit, or the like is preferably used as the storage unit used at that time.

  In addition, the reversible thermosensitive recording medium of the present invention can be processed into a shape according to its use, and processed into a card shape, a sheet shape, a roll shape, and the like. For cards processed into cards, application to prepaid cards, point cards, credit cards, etc. can be mentioned. Sheets processed into general document sizes such as A4 size can be printed by using a printing / erasing device. In addition to trial printing, it can be widely used for temporary output such as circulation documents and conference materials. Furthermore, what was processed into the roll shape can be used for a display board, a bulletin board, or an electronic blackboard by incorporating in a device having a printing / erasing section. Such a display device can be preferably used in a clean room or the like because it does not generate dust or dust.

  The reversible thermosensitive recording medium of the present invention may be used in combination with an irreversible thermosensitive recording layer. At this time, the color tone of each recording layer may be the same or different. In addition, on the same side and / or the opposite side of the heat-sensitive recording layer of the reversible thermosensitive recording medium of the present invention, a part or the whole of the surface is arbitrarily selected by printing such as offset printing, gravure printing, or an inkjet printer, thermal transfer printer, sublimation printer, etc. A colored layer having the above-described pattern or the like may be provided, and an OP varnish layer mainly composed of a curable resin may be provided on a part or the entire surface of the colored layer. In the case of laminating, the above-described printing can be performed in advance on the support and the base sheet to be bonded. Examples of the arbitrary pattern include characters, patterns, patterns, photographs, information detected by infrared rays, and the like. It is also possible to add a dye or pigment to any one of the simply configured layers for coloring.

Furthermore, a hologram can be provided for security. For embossing, character images, Braille information, or reliefs and intaglio shapes can be added to provide design such as a person image, a company emblem, a symbol mark, etc.
Thus, the present invention can provide a reversible thermosensitive recording medium having a reversible thermosensitive recording section and an information storage section.
In addition, the present invention can provide a reversible thermosensitive recording medium characterized in that irreversible visible information is previously formed on at least a part of the surface and / or the back surface of the thermosensitive recording surface.
Furthermore, the present invention can provide a reversible thermosensitive recording medium processed into a card shape, a sheet shape or a roll shape.
The present invention can also provide a printing / erasing apparatus using a reversible thermosensitive recording medium processed into a card shape or a sheet shape.
In addition, the present invention can provide a display device characterized by having a printing / erasing unit that incorporates and uses a reversible thermosensitive recording medium processed into a roll shape.
Furthermore, the present invention can provide a display device that is any one of a display board, a bulletin board, and an electronic blackboard.
Furthermore, the present invention can provide a reversible thermosensitive recording label characterized in that an adhesive layer or a pressure-sensitive adhesive layer is provided on the side opposite to the thermosensitive recording surface side of the support of the reversible thermosensitive recording medium.

Next, an image forming and / or erasing method of the reversible thermosensitive recording medium of the present invention will be described.
In order to form a color image using the reversible thermosensitive recording medium of the present invention, the color image may be rapidly cooled after being heated above the color development temperature. Specifically, for example, when the thermal recording layer is heated for a short time with a thermal head or laser light, the heat-sensitive recording layer is locally heated, so that the heat is immediately diffused and rapid cooling occurs, and the color development state can be fixed.

  On the other hand, in order to erase the color, it may be heated and cooled for a relatively long time using an appropriate heat source, or may be temporarily heated to a temperature slightly lower than the coloring temperature. When heated for a long time, the temperature of a wide range of the recording medium rises, and the subsequent cooling becomes slow. As a heating method in this case, a hot roller, a hot stamp, hot air, or the like may be used, or heating may be performed for a long time using a thermal head.

  Further, in order to heat the thermosensitive recording layer to the decoloring temperature range, for example, the applied energy may be lowered slightly from the time of recording by adjusting the voltage applied to the thermal head and the pulse width. If this method is used, recording / erasing can be performed only by the thermal head, and so-called overwriting becomes possible. Of course, it can be erased by heating to a decoloring temperature range with a heat roller or a heat stamp.

  Accordingly, the present invention can provide an image forming / erasing method characterized in that an image is formed and / or erased by heating a reversible thermosensitive recording medium.

  In addition, the surface of the reversible thermosensitive recording medium of the present invention is the surface of the thermosensitive recording layer side and is not limited to the protective layer, but is a thermal head for erasing printing such as the printing layer surface, OP layer surface, and laminate layer surface. Means all or part of the surface that contacts

Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to the examples. In the examples, “parts” and “%” are based on weight.
Example 1
(Preparation of thermal recording layer)
[Liquid A]
3-Diethylamino-6-methyl-7-anilinofluorane 3 parts Developer with the following structure 9 parts Acrylic polyol resin 40% solution (Mitsubishi Rayon Co., Ltd .: FR5153) 30 parts

メチルエチルケトン ４８部
上記組成物をペイントシェーカーにて粒径１．０μｍまで粉砕分散した。
〔感熱記録層塗布液１〕
得られた顕色剤分散液〔Ａ液〕に
アダクト型ヘキサメチレンジイソシアネート７５％酢酸エチル溶液
（日本ポリウレタン社製：コロネートＨＬ） ８部
２−メタクリロイルオキシエチルイソシアネート
（昭和電工社製：カレンズＭＯＩ） ２部
を加え、よく撹拌し感熱記録層塗布液１を調製した。上記組成の感熱記録層塗布液１を、厚さ２５０μｍの白色ＰＥＴフィルム上にワイヤーバーを用いて塗布し、１００℃で乾燥した後、６０℃で２４時間加熱して、膜厚約１１μｍの感熱記録層を設けた。
（保護層の作製）
シリカ
（富士シリシア社製：サイリシア３１０Ｐ：粒径１．４μｍ） ２部
ウレタンアクリレート
（根上工業社製：アートレジンＵＮ−３３２０ＨＡ） ４部
ポリエステルアクリレート
（ダイセル化学工業社製：エベクリル１８１０） ２部
トリス（アクリロキシエチル）イソシアヌレート
（日立化成社製：ＦＡ−７３１Ａ） ２部
光重合開始剤
（日本チバガイギー社製：イルガキュア９０７） ０．４部
トルエン １８部
上記組成物をペイントシェーカーにて３０分間振盪して保護層塗布液１を調整した。この保護層塗布液１を前記感熱記録層塗布済みフィルム上にワイヤーバーにて塗布、７０℃で加熱乾燥した後、照射エネルギー８０Ｗ／ｃｍの紫外線ランプ下を１０ｍ／分の搬送速度で通して硬化させた後、６０℃で２４時間加熱して膜厚約６μｍの保護層を設け、可逆性感熱記録媒体を作製した。
実施例２
（感熱記録層の作製）
〔感熱記録層塗布液２〕
顕色剤分散液〔Ａ液〕に
アダクト型ヘキサメチレンジイソシアネート７５％酢酸エチル溶液
（日本ポリウレタン社製：コロネートＨＬ） １０部
を加え、よく撹拌し感熱記録層塗布液２を調製した。上記組成の感熱記録層塗布液２を、厚さ２５０μｍの白色ＰＥＴフィルム上にワイヤーバーを用いて塗布し、１００℃で乾燥した後、６０℃で２４時間加熱して、膜厚約１１μｍの感熱記録層を設けた。
（保護層の作製）
シリカ
（富士シリシア社製：サイリシア３１０Ｐ：粒径１．４μｍ） ２部
ウレタンアクリレート
（根上工業社製：アートレジンＵＮ−３３２０ＨＡ） ３．５部
ポリエステルアクリレート
（ダイセル化学工業社製：エベクリル１８１０） １．８部
トリス（アクリロキシエチル）イソシアヌレート
（日立化成社製：ＦＡ−７３１Ａ） １．７部
２−メタクリロイルオキシエチルイソシアネート
（昭和電工社製：カレンズＭＯＩ） １部
光重合開始剤
（日本チバガイギー社製：イルガキュア９０７） ０．４部
トルエン １８部
上記組成物をペイントシェーカーにて３０分間振盪して保護層塗布液２を調整した。この保護層塗布液２を前記感熱記録層塗布済みフィルム上にワイヤーバーにて塗布、７０℃で加熱乾燥した後、照射エネルギー８０Ｗ／ｃｍの紫外線ランプ下を１０ｍ／分の搬送速度で通して硬化させた後、６０℃で２４時間加熱して膜厚約６μｍの保護層を設け、可逆性感熱記録媒体を作製した。
実施例３
（感熱記録層の作製）
感熱記録層塗布液２を、厚さ２５０μｍの白色ＰＥＴフィルム上にワイヤーバーを用いて塗布し、１００℃で乾燥した後、６０℃で２４時間加熱して、膜厚約１１μｍの感熱記録層を設けた。
（第１保護層の作製）
アクリルポリオール樹脂４０％溶液
（三菱レーヨン社製：ＦＲ５１１３） １５部
コロネートＨＬ ４部
２−メタクリロイルオキシエチルイソシアネート １部
メチルエチルケトン １０部
上記組成物を良く攪拌して調製した第１保護層塗布液をワイヤーバーで塗布し、９０℃１分で乾燥した後、７０℃２時間加熱して、膜厚約２μｍの中間層を設けた。引き続き保護層塗布液１をワイヤーバーにて塗布、７０℃で加熱乾燥した後、照射エネルギー８０Ｗ／ｃｍの紫外線ランプ下を１０ｍ／分の搬送速度で通して硬化させた後、６０℃で２４時間加熱して膜厚約４μｍの第２保護層を設け、可逆性感熱記録媒体を作製した。
実施例４
第１保護層を下記処方にする以外は実施例３と同様に感熱記録層、第１保護層、第２保護層を設け、可逆性感熱記録媒体を作製した。
（第１保護層の作製）
エポキシ樹脂主剤
（旭電化工業社製：アデカレジンＥＰＲ−４０２６） ４０部
エポキシ樹脂硬化剤
（旭電化工業社製：アデカハードナーＧＭ６５０） １６部
ビスフェノールＡ型部分アクリル化エポキシ
（ダイセル化学工業社製：ウバキュア１５６１） １４部
トルエン ３０部
実施例５
第１保護層を下記処方にする以外は実施例３と同様に感熱記録層、第１保護層、第２保護層を設け、可逆性感熱記録媒体を作製した。
（第１保護層の作製）
アクリルポリオール樹脂４０％溶液
（三菱レーヨン社製：ＦＲ５１１３） １５部
コロネートＨＬ ４部
２−メタクリロイルオキシエチルイソシアネート １部
ベンゾトリアゾール系紫外線吸収剤
（ケミプロ化成社製：ケミソーブ７３） ２部
メチルエチルケトン １０部
実施例６
第１保護層を下記処方にする以外は実施例３と同様に感熱記録層、第１保護層、第２保護層を設け、可逆性感熱記録媒体を作製した。
（第１保護層の作製）
アクリルポリオール樹脂４０％溶液
（三菱レーヨン社製：ＦＲ５１１３） １５部
コロネートＨＬ ４部
２−メタクリロイルオキシエチルイソシアネート １部
酸化亜鉛超微粒子
（住友大阪セメント社製：ＺｎＯ−３０５） ２部
メチルエチルケトン １０部
実施例７
第１保護層を下記処方にする以外は実施例３と同様に感熱記録層、第１保護層、第２保護層を設け、可逆性感熱記録媒体を作製した。
（第１保護層の作製）
アクリルポリオール樹脂４０％溶液
（三菱レーヨン社製：ＦＲ５１１３） １５部
コロネートＨＬ ４部
２−メタクリロイルオキシエチルイソシアネート １部
シリコーン被覆酸化亜鉛超微粒子
（住友大阪セメント社製：ＺｎＯ−３０５Ｓｉ（４）Ｇ） ２部
メチルエチルケトン １０部
実施例８
第１保護層を下記処方にする以外は実施例３と同様に感熱記録層、第１保護層、第２保護層を設け、可逆性感熱記録媒体を作製した。
（第１保護層の作製）
アクリルポリオール樹脂４０％溶液
（三菱レーヨン社製：ＦＲ５１１３） １５部
コロネートＨＬ ４部
２−メタクリロイルオキシエチルイソシアネート １部
メタクリレート型紫外線吸収剤
（新中村化学社製：バナレジンＵＶＡ−１０５０Ｇ） ４部
メチルエチルケトン ６部
比較例１
実施例１と同様に感熱記録層塗布液２、保護層塗布液１を塗布し、可逆性感熱記録媒体を作製した。
比較例２
感熱記録層塗布液を下記処方にする以外は実施例１と同様に感熱記録層、保護層を設け、可逆性感熱記録媒体を作製した。
〔Ａ液〕 ９０部
アダクト型ヘキサメチレンジイソシアネート７５％酢酸エチル溶液
（日本ポリウレタン社製：コロネートＨＬ） ８部
ウレタンアクリレート
（根上工業社製：アートレジンＵＮ−３３２０ＨＡ） ２部
比較例３
第１保護層を下記処方にする以外は実施例３と同様に感熱記録層、第１保護層、第２保護層を設け、可逆性感熱記録媒体を作製した。
（第１保護層の作製）
アクリルポリオール樹脂４０％溶液
（三菱レーヨン社製：ＦＲ５１１３） １５部
コロネートＨＬ ５部
メチルエチルケトン １０部
以上の様に作製した可逆性感熱記録媒体の接着性、繰り返し耐久性、及び画像鮮明性の評価結果を表１に示す。

48 parts of methyl ethyl ketone The above composition was pulverized and dispersed with a paint shaker to a particle size of 1.0 μm.
[Thermosensitive recording layer coating solution 1]
Adduct type hexamethylene diisocyanate 75% ethyl acetate solution (manufactured by Nippon Polyurethane Co., Ltd .: Coronate HL) 8 parts 2-methacryloyloxyethyl isocyanate (manufactured by Showa Denko KK: Karenz MOI) 2 Part was added and stirred well to prepare a thermal recording layer coating solution 1. The thermosensitive recording layer coating solution 1 having the above composition is coated on a white PET film having a thickness of 250 μm using a wire bar, dried at 100 ° C., and then heated at 60 ° C. for 24 hours to have a thermal sensitivity of about 11 μm. A recording layer was provided.
(Preparation of protective layer)
Silica (Fuji Silysia, Inc .: Silicia 310P: particle size 1.4 μm) 2 parts Urethane acrylate (Negami Kogyo Co., Ltd .: Art Resin UN-3320HA) 4 parts Polyester acrylate (Daicel Chemical Industries, Ltd .: Eveacryl 1810) 2 parts Tris ( Acryloxyethyl) isocyanurate (manufactured by Hitachi Chemical Co., Ltd .: FA-731A) 2 parts Photopolymerization initiator (manufactured by Ciba Geigy Japan Inc .: Irgacure 907) 0.4 parts Toluene 18 parts The above composition was shaken for 30 minutes in a paint shaker. The protective layer coating solution 1 was prepared. This protective layer coating solution 1 is applied onto the heat-sensitive recording layer-coated film with a wire bar, dried by heating at 70 ° C., and then cured by passing it under an ultraviolet lamp with an irradiation energy of 80 W / cm at a conveyance speed of 10 m / min. Then, the film was heated at 60 ° C. for 24 hours to provide a protective layer having a film thickness of about 6 μm, and a reversible thermosensitive recording medium was produced.
Example 2
(Preparation of thermal recording layer)
[Thermosensitive recording layer coating solution 2]
10 parts of adduct-type hexamethylene diisocyanate 75% ethyl acetate solution (manufactured by Nippon Polyurethane Co., Ltd .: Coronate HL) was added to the developer dispersion liquid [A liquid] and stirred well to prepare a thermal recording layer coating liquid 2. The thermosensitive recording layer coating solution 2 having the above composition was applied onto a white PET film having a thickness of 250 μm using a wire bar, dried at 100 ° C., and then heated at 60 ° C. for 24 hours to give a thermosensitive film having a thickness of about 11 μm. A recording layer was provided.
(Preparation of protective layer)
Silica (Fuji Silysia, Inc .: Silicia 310P: particle size 1.4 μm) 2 parts Urethane acrylate (Negami Kogyo Co., Ltd .: Art Resin UN-3320HA) 3.5 parts Polyester acrylate (Daicel Chemical Industries, Ltd .: Eveacryl 1810) 8 parts Tris (acryloxyethyl) isocyanurate (manufactured by Hitachi Chemical Co., Ltd .: FA-731A) 1.7 parts 2-methacryloyloxyethyl isocyanate (manufactured by Showa Denko KK: Karenz MOI) 1 part Photopolymerization initiator (manufactured by Ciba Geigy Japan) : Irgacure 907) 0.4 part Toluene 18 parts The composition was shaken for 30 minutes with a paint shaker to prepare a protective layer coating solution 2. This protective layer coating solution 2 is applied onto the heat-sensitive recording layer-coated film with a wire bar, heated and dried at 70 ° C., and then cured by passing through a UV lamp with an irradiation energy of 80 W / cm at a conveyance speed of 10 m / min. Then, the film was heated at 60 ° C. for 24 hours to provide a protective layer having a film thickness of about 6 μm, and a reversible thermosensitive recording medium was produced.
Example 3
(Preparation of thermal recording layer)
The thermal recording layer coating solution 2 was applied onto a white PET film having a thickness of 250 μm using a wire bar, dried at 100 ° C., and then heated at 60 ° C. for 24 hours to form a thermal recording layer having a thickness of about 11 μm. Provided.
(Preparation of the first protective layer)
Acrylic polyol resin 40% solution (Made by Mitsubishi Rayon: FR5113) 15 parts Coronate HL 4 parts 2-Methacryloyloxyethyl isocyanate 1 part Methyl ethyl ketone 10 parts The first protective layer coating solution prepared by thoroughly stirring the above composition is a wire bar. After coating at 90 ° C. for 1 minute, heating was performed at 70 ° C. for 2 hours to provide an intermediate layer having a thickness of about 2 μm. Subsequently, the protective layer coating solution 1 was applied with a wire bar, dried by heating at 70 ° C., and then cured by passing under a UV lamp with an irradiation energy of 80 W / cm at a conveyance speed of 10 m / min, and then at 60 ° C. for 24 hours. A second protective layer having a thickness of about 4 μm was provided by heating to produce a reversible thermosensitive recording medium.
Example 4
A heat-sensitive recording layer, a first protective layer, and a second protective layer were provided in the same manner as in Example 3 except that the first protective layer was formulated as follows to prepare a reversible thermosensitive recording medium.
(Preparation of the first protective layer)
Epoxy resin main agent (Asahi Denka Kogyo Co., Ltd .: Adeka Resin EPR-4026) 40 parts Epoxy resin curing agent (Asahi Denka Kogyo Co., Ltd .: Adeka Hardener GM650) 16 parts Bisphenol A type partially acrylated epoxy (Daicel Chemical Industries, Ltd .: UbaCure 1561) ) 14 parts Toluene 30 parts Example 5
A heat-sensitive recording layer, a first protective layer, and a second protective layer were provided in the same manner as in Example 3 except that the first protective layer was formulated as follows to prepare a reversible thermosensitive recording medium.
(Preparation of the first protective layer)
Acrylic polyol resin 40% solution (Mitsubishi Rayon Co., Ltd .: FR5113) 15 parts Coronate HL 4 parts 2-Methacryloyloxyethyl isocyanate 1 part Benzotriazole UV absorber (Chemipro Kasei Co., Ltd .: Chemisorb 73) 2 parts Methyl ethyl ketone 10 parts Examples 6
A heat-sensitive recording layer, a first protective layer, and a second protective layer were provided in the same manner as in Example 3 except that the first protective layer was formulated as follows to prepare a reversible thermosensitive recording medium.
(Preparation of the first protective layer)
Acrylic polyol resin 40% solution (Mitsubishi Rayon Co., Ltd .: FR5113) 15 parts Coronate HL 4 parts 2-methacryloyloxyethyl isocyanate 1 part Zinc oxide ultrafine particles (Sumitomo Osaka Cement Co., Ltd .: ZnO-305) 2 parts Methyl ethyl ketone 10 parts Examples 7
A heat-sensitive recording layer, a first protective layer, and a second protective layer were provided in the same manner as in Example 3 except that the first protective layer was formulated as follows to prepare a reversible thermosensitive recording medium.
(Preparation of the first protective layer)
Acrylic polyol resin 40% solution (Mitsubishi Rayon: FR5113) 15 parts Coronate HL 4 parts 2-methacryloyloxyethyl isocyanate 1 part Silicone coated zinc oxide ultrafine particles (Sumitomo Osaka Cement Co., Ltd .: ZnO-305Si (4) G) 2 Part Methyl ethyl ketone 10 parts Example 8
A heat-sensitive recording layer, a first protective layer, and a second protective layer were provided in the same manner as in Example 3 except that the first protective layer was formulated as follows to prepare a reversible thermosensitive recording medium.
(Preparation of the first protective layer)
Acrylic polyol resin 40% solution (Mitsubishi Rayon Co., Ltd .: FR5113) 15 parts Coronate HL 4 parts 2-Methacryloyloxyethyl isocyanate 1 part Methacrylate type UV absorber (Shin Nakamura Chemical Co., Ltd .: Vanaresin UVA-1050G) 4 parts Methyl ethyl ketone 6 parts Comparative Example 1
In the same manner as in Example 1, the thermosensitive recording layer coating solution 2 and the protective layer coating solution 1 were applied to produce a reversible thermosensitive recording medium.
Comparative Example 2
A reversible thermosensitive recording medium was prepared by providing a thermosensitive recording layer and a protective layer in the same manner as in Example 1 except that the thermosensitive recording layer coating solution was formulated as follows.
[Liquid A] 90 parts Adduct type hexamethylene diisocyanate 75% ethyl acetate solution (manufactured by Nippon Polyurethane Co., Ltd .: Coronate HL) 8 parts Urethane acrylate (manufactured by Negami Kogyo Co., Ltd .: Art Resin UN-3320HA) 2 parts Comparative Example 3
A heat-sensitive recording layer, a first protective layer, and a second protective layer were provided in the same manner as in Example 3 except that the first protective layer was formulated as follows to prepare a reversible thermosensitive recording medium.
(Preparation of the first protective layer)
Acrylic polyol resin 40% solution (manufactured by Mitsubishi Rayon Co., Ltd .: FR5113) 15 parts Coronate HL 5 parts Methyl ethyl ketone 10 parts Evaluation results of adhesiveness, repetitive durability, and image sharpness of the reversible thermosensitive recording medium produced as described above Table 1 shows.

  Adhesiveness is 11 mm in length and breadth on the recording surface side of the medium in parallel with a cutter at 1 mm intervals, and the surface is rubbed by attaching cellophane tape from the upper surface, and after standing for 2 minutes, the surface is vertical. It peeled off at a stretch in the direction and evaluated. For the method of evaluating the durability of repeated images, the reversible thermosensitive recording media obtained in the above examples and comparative examples were punched out into a credit card, and the card printer R-28000 (manufactured by Panasonic Communications Co., Ltd.) was used. Printing was performed in the erase print mode. The erasure printing is a method in which an image is rewritten by inserting and reciprocating the card once and inserting the card again. The erasing is performed by a ceramic heater (erase bar), and the printing is continuously performed by a thermal head. As the conditions, the printing energy was set to about 0.82 mJ / dot, and the erasing energy of the ceramic heater was set to the center value of a region where there was no disappearance due to lack of energy and there was no fogging due to over energy.

  The repeated test was conducted manually in consideration of actual use. That is, every time printing is performed, the entire surface of the recording surface is touched with the belly of the finger, and erasure printing is performed again after 3 minutes.

接着性
１００マスのうち媒体からの層剥離が確認されなかったマスの数。
画像鮮明性
◎：無印字部が白く鮮明で、印字画像が明確に判別できた
○：無印字部に着色が見られるが、印字画像が明確に判別できた
試験後剥離
◎：印字履歴のある部分も均一なベタ画像が得られた
○：多少の表面の荒れがあるが、
×：画像の中に空気層のようなものが入り
細線再現性
◎：１乃至３ドットで印字された文字が、初期と同様に明確に判読できた
○：多少のかすれが見られるが、文字を判読できた
×：１乃至３ドットで印字された文字が読めない
以上のように、本発明によって、層間結着力が向上し、画像鮮明性や繰り返し耐久性の優れた可逆性感熱記録媒体を提供できる。
また、かかる可逆性感熱記録媒体は情報記憶部（磁気記録層、ＩＣメモリー、光メモリーなど）や予め不可逆な可視情報を設けた形状を成すことが可能であり、また、粘着層を付加して感熱記憶ラベルと成すことで、より利便性が向上し、実用性の高いものとなる。さらに、使用用途に応じた形状に加工でき、例えば、カード及びシート状のものは装置によって印字／消去でき、ロール状のものは電子黒板などの表示装置に組み込んで印字／消去できる。

Adhesiveness The number of squares in which no delamination from the medium was confirmed.
Image sharpness ◎: The non-printed area is white and clear, and the printed image can be clearly discriminated ○: Color is seen in the non-printed area, but the printed image can be clearly discriminated ◎: There is a print history A uniform solid image was also obtained in the area. ○: Although there is some surface roughness,
×: An air layer is included in the image Fine line reproducibility ◎: Characters printed with 1 to 3 dots were clearly readable as in the initial state ○: Some blurring was observed, but characters As described above, according to the present invention, a reversible thermosensitive recording medium with improved interlayer binding force and excellent image sharpness and repeated durability is obtained. Can be provided.
Such a reversible thermosensitive recording medium can have a shape provided with an information storage unit (magnetic recording layer, IC memory, optical memory, etc.) or irreversible visible information in advance, and an adhesive layer is added. By using a thermosensitive memory label, the convenience is further improved and it becomes highly practical. Further, it can be processed into a shape according to the intended use. For example, cards and sheets can be printed / erased by the apparatus, and rolls can be incorporated into a display device such as an electronic blackboard and printed / erased.

  Furthermore, the reversible thermosensitive recording medium can form and erase images by heating using a thermal head or the like, and includes at least one of a thermal head, a ceramic heater, a heat roll, a hot stamp, and a heat block. The image can be erased by using and heating.

It is the schematic explaining the typical reversible thermosensitive recording medium of this invention. It is a figure which shows an example of the thermocompression bonding process of the reversible thermosensitive recording label and base sheet in this invention. It is a figure which shows an example of the thermocompression bonding process of the reversible thermosensitive recording label and base sheet in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hot plate 2 Mirror surface plate 3 Reversible thermosensitive recording label 4 Base sheet 5 Reversible thermosensitive recording medium 6 Core sheet 7 Oversheet

Claims (16)

It contains an electron-donating color-forming compound and an electron-accepting compound as main components on the support, and forms a relatively colored state and a decolored state depending on the heating temperature and / or the cooling rate after heating. In a reversible thermosensitive recording medium comprising at least one protective layer on the reversible thermosensitive recording layer containing the reversible thermosensitive composition to be obtained, and
The curing method of the uppermost layer and the adjacent layer is different, and at least one of the uppermost layer and the adjacent lower layer contains a compound having simultaneously functional groups that are cured by the respective curing methods in the same molecule. A reversible thermosensitive recording medium.   The uppermost layer of the reversible thermosensitive recording medium is mainly composed of a cured UV curable resin or electron beam curable resin, and a functional group that photoreacts with a functional group that reacts thermally with a layer adjacent to the uppermost layer is contained in the same molecule. The reversible thermosensitive recording medium according to claim 1, comprising a compound simultaneously contained in and cured.   A protective layer formed on the reversible thermosensitive recording layer is formed of two layers, the reversible thermosensitive recording layer and the adjacent first protective layer are mainly composed of a resin crosslinked by heat, and the first protection 3. The reversible thermosensitive recording medium according to claim 1, wherein the second protective layer adjacent to the uppermost layer is composed mainly of a resin crosslinked by light.   The reversible thermosensitive recording medium according to claim 3, wherein the first protective layer contains an ultraviolet shielding component.   5. The reversible thermosensitive recording medium according to claim 4, wherein the first protective layer contains an ultrafine metal oxide as an ultraviolet shielding component.   6. The reversible thermosensitive recording medium according to claim 5, wherein the ultrafine metal oxide has a primary particle diameter of 100 nm or less and a surface subjected to a hydrophobic treatment.   5. The reversible thermosensitive recording medium according to claim 4, wherein the first protective layer contains an organic polymer having an ultraviolet absorbing structure as an ultraviolet shielding component.   The reversible thermosensitive recording medium according to any one of claims 1 to 7, wherein the support on which two or more kinds of sheets are bonded is used.   The reversible thermosensitive recording medium according to any one of claims 1 to 8, further comprising a reversible thermosensitive recording unit and an information storage unit.   10. The reversible thermosensitive recording medium according to any one of claims 1 to 9, wherein irreversible visible information is formed in advance on at least a part of the front surface and / or the back surface of the thermosensitive recording surface.   The reversible thermosensitive recording medium according to any one of claims 1 to 10, wherein the reversible thermosensitive recording medium is processed into a card shape, a sheet shape, or a roll shape.   A printing / erasing apparatus using a reversible thermosensitive recording medium processed into a card shape or a sheet shape.   A display device comprising a printing / erasing unit that incorporates and uses a reversible thermosensitive recording medium processed into a roll.   The display device according to claim 13, wherein the display device is any one of a display board, a bulletin board, and an electronic blackboard.   12. A reversible thermosensitive recording comprising an adhesive layer or a pressure-sensitive adhesive layer provided on the opposite side of the support of the reversible thermosensitive recording medium according to any one of claims 1 to 11. label.   13. An image forming / erasing method comprising forming an image and / or erasing an image of the reversible thermosensitive recording medium according to any one of claims 1 to 12 by heating.

Images