JP2007331382A - Reversible heat-sensitive recording medium, reversible heat-sensitive recording label, reversible heat-sensitive recording member, image processing device and image processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reversible heat-sensitive recording medium which is free from generation of surface cracks, even in case it is handled like a paper and does not become curled even when such handling is repeated, and makes the attributes of a conventional medium such as printability, adhesion and conveyability compatible with each other, and enables stable repeating of color development and color fading, and a reversible heat-sensitive recording label, a reversible heat-sensitive recording member, an image processing device and an image processing method. <P>SOLUTION: This reversible heat-sensitive recording medium comprises a support, a heat-sensitive recording layer formed on the support, and a protecting layer formed on the heat-sensitive recording layer. In addition, the heat-sensitive recording layer includes an electron-donating coloring compound and an electron-accepting compound, and shows a reversibly changing color tone depending on temperature. Further, the protecting layer is composed of the reversible heat-sensitive recording medium comprising a polymerization product of a composition which comprises two kinds of acrylate compounds selected from a group consisting of acrylate compounds with a pentaerythritol group and acrylate compounds with a dipentaerythritol compound. <P>COPYRIGHT: (C)2008,JPO&INPIT

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, a reversible thermosensitive recording label using the reversible thermosensitive recording medium, a reversible thermosensitive recording member, an image processing apparatus, and an image processing method.

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

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

Further, by using an organic phosphoric acid compound having a long-chain aliphatic hydrocarbon group, an aliphatic carboxylic acid compound or a phenol compound as a developer, and combining the compound with a leuco dye as a color former, coloring and decoloring are achieved. Is a reversible thermosensitive coloring composition that can maintain the coloring state and the decoloring state stably at room temperature, and can repeat the coloring and decoloring. , And reversible thermosensitive recording media using the thermosensitive recording layer have been developed (see Patent Document 11, Patent Document 12, and Patent Document 13).
However, in a conventional reversible thermosensitive recording medium, when an image is formed by heating with a heating body such as a thermal head, the frictional force between the heating body and the thermosensitive recording layer is large, and sticking may occur. Since the surface is easily deformed by pressure, the surface has periodic irregularities corresponding to the dot density of the thermal head, and the amount of deformation increases as image formation and erasure are repeated, thereby forming a clear image. Was difficult.

  In order to solve this problem, a method has been proposed in which a protective layer such as silicone resin or silicone rubber is provided to reduce the friction coefficient of the surface (see Patent Document 14). However, since this protective layer has insufficient adhesion to the heat-sensitive recording layer, there is a problem that the protective layer is peeled off by repeated mechanical action and the image is deteriorated. In order to improve the adhesion, a reversible thermosensitive recording medium in which an intermediate layer mainly composed of a resin and a protective layer mainly composed of a heat-resistant resin are sequentially provided on the thermosensitive recording layer has been proposed. (See Patent Document 15). According to this proposal, the adhesiveness is improved by the intermediate layer, and the deformation of the reversible recording medium surface is reduced by the protective layer made of the heat resistant resin. However, even in this proposal, if printing and erasing are repeated many times, scratches occur due to sticking, or a part of the protective layer peels off and adheres to the thermal head. Therefore, it was difficult to form a clear image.

Further, in order to solve these problems, the peak temperature of tan δ (tan δ = ratio G ″ / G ′ of dynamic (storage) elastic modulus G ′ and dynamic elastic loss rate G ″) of 250 ° C. or lower is applied on the thermosensitive recording layer. Alternatively, a reversible thermosensitive recording medium having a protective layer that does not have a corresponding dynamic relaxation phenomenon temperature has been proposed (see Patent Document 16). In this proposal, even if image formation and erasure are repeatedly performed by a heating element such as a thermal head by the protective layer, generation of periodic surface irregularities corresponding to the dot density of the thermal head can be considerably suppressed.
However, as the image processing speed of the image processing apparatus that performs image formation and erasure increases, in order to shorten the image processing with a thermal head or the like, when the energy application time is set to a short pulse on the order of several milliseconds, a clear image In the case where the pressure applied by a heating body such as a thermal head is increased in order to obtain the image, there is a problem that cracks occur on the surface of the protective layer when image formation and erasure are repeated. Further, there is a problem that the surface state of the protective layer is deteriorated with an increase in the amount of cracks generated, sticking occurs due to deterioration of the transportability in the image processing apparatus, and the image is deteriorated.

In order to solve these problems, the protective layer contains an ultraviolet curable resin composition, and the ultraviolet curable composition is an epoxy acrylate having a bisphenol A skeleton and an acrylate ester of a bisphenol A diglycidyl ether polymer, Alternatively, it contains dipentaerythritol monohydroxypentaacrylate, and the irradiation energy is 150 mJ / cm ^{2 to} 1,500 mJ / w so that the tan δ peak temperature of the protective layer or the corresponding dynamic relaxation phenomenon temperature is 155 ° C. or lower. A reversible thermosensitive recording medium having a protective layer formed by irradiating ultraviolet rays of cm ² has been proposed (see Patent Document 17).
However, reversible thermosensitive recording media that have been proposed so far are widely used as magnetic thermosensitive cards such as prepaid cards and point cards. In this field, thermal recording media for image forming and erasing as described above are used. Only the interaction between the head and the reversible thermosensitive recording medium was discussed, and the bending of the reversible thermosensitive recording medium by the operator was not assumed at all from the size of the form and the thickness of the card.

  However, recent reversible thermosensitive recording media are rapidly spreading to OA applications such as test printing and conference materials that can only be used once, and parts management and process management applications in factories. In the field, compared with the conventional card field, the display area is widely required from Kanban (A6) size to A5 size, A4 size, and A3 size. Therefore, since it is handled like paper, which is not supposed at all in the use of magnetic thermosensitive cards such as conventional prepaid cards and point cards, the conventional protective layer, which emphasized the physical strength with the thermal head, is used. If the protective layer is too hard and cracks occur on the surface of the medium before handling it repeatedly, the image deteriorates, and if the image is repeatedly formed and erased, the thermal recording surface side is reversible. A new problem such as curling of the thermal recording medium that has been unforeseen has occurred, and it is currently desired to quickly solve these problems.

JP 63-107584 A JP-A-4-78573 Japanese Patent Laid-Open No. 60-193691 Japanese Patent Laid-Open No. Sho 61-237684 JP-A-62-138556 JP-A-62-138568 JP-A-62-140881 Japanese Patent Laid-Open No. 63-173684 JP-A-2-188293 JP-A-2-188294 JP-A-5-124360 Japanese Patent Laid-Open No. 6-210954 JP-A-10-95175 JP-A-62-55650 Japanese Unexamined Patent Publication No. 1-133781 JP-A-9-142037 JP 11-334220 A

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention does not cause surface cracks even when handled like paper, does not curl the medium even if it is repeated, and has the printability, adhesiveness, and transportability possessed by conventional media. Reversible thermosensitive recording medium capable of achieving both compatibility and stable repetition of color development and decoloring, reversible thermosensitive recording label, reversible thermosensitive recording member, image processing apparatus and image processing method using the reversible thermosensitive recording medium The purpose is to provide.

  As a result of intensive studies by the present inventors in order to solve the above problems, in a reversible thermosensitive recording medium having a support, a thermosensitive recording layer on the support, and a protective layer on the thermosensitive recording layer, An acrylate compound in which the protective layer is a combination of two types of acrylates having a pentaerythritol group or a dipentaerythritol group, one of which is a direct bond of a pentaerythritol group or a dipentaerythritol group and a polymerizable group having an ester bond (A And the other is a pentaerythritol group or a dipentaerythritol group and a polymerizable group having an ester bond, and an acrylate compound (B) having a hydrocarbon group that may also have a substituent having an ester bond The effect is enhanced, and the blending mass ratio of the two acrylate compounds (A) and (B) is (A) / (B). By setting the ratio to 1.0 / 9.0 to 5.0 / 5.0, it is possible to improve cracks, curls, and adhesion without causing surface cracks even when handled like paper. I found out that

Means for solving the problems are as follows. That is,
<1> In a reversible thermosensitive recording medium having a support, a thermosensitive recording layer on the support, and a protective layer on the thermosensitive recording layer,
The thermosensitive recording layer contains an electron-donating color-forming compound and an electron-accepting compound, and the color tone reversibly changes depending on the temperature,
The reversible thermosensitive recording medium, wherein the protective layer contains a polymer of a composition containing two acrylate compounds selected from an acrylate compound having a pentaerythritol group and an acrylate compound having a dipentaerythritol group. It is.
<2> Of the two acrylate compounds, one is an acrylate compound (A) in which either a pentaerythritol group or a dipentaerythritol group and a polymerizable group having an ester bond are directly bonded,
The other is an acrylate compound having a chain hydrocarbon group which may have a substituent having an ester bond between either a pentaerythritol group or a dipentaerythritol group and a polymerizable group having an ester bond ( The reversible thermosensitive recording medium according to <1>, which is B).
<3> In the above <2>, the blending mass ratio of the two acrylate compounds (A) and (B) is (A) / (B) = 1.0 / 9.0 to 5.0 / 5.0. The reversible thermosensitive recording medium described.
<4> The reversible thermosensitive recording medium according to any one of <1> to <3>, wherein the two acrylate compounds are represented by the following structural formulas (1) and (2).
However, in the structural formulas (1) and (2), X represents a pentaerythritol group or a dipentaerythritol group. Y _{is, -CH 2 O -, - CH} 2 CH 2 O -, - CH 2 CH 2 CH 2 O -, - CH 2 CH 2 CH 2 CH 2 O -, - CH 2 CH 2 CH 2 CH 2 CH 2 _{O -, - CH 2 CH (} CH 3) O-, or _{-CO-CH 2 CH 2 CH 2} CH 2 represent a _CH 2 O-. Z represents -H or -CO-CH = CH _2,. a represents 1 to 5, b represents 1 to 5, and c represents 1 to 12, respectively.
<5> The reversible thermosensitive recording medium according to any one of <1> to <4>, wherein the electron-accepting compound is a phenol compound represented by any one of the following structural formulas (3) and (4): .
However, in said structural formula (3), X and Y represent the bivalent organic group containing a hetero atom. R ³ represents a divalent hydrocarbon group which may have a substituent. R ⁴ represents a monovalent hydrocarbon group which may have a substituent. n represents an integer of 1 to 3, m represents an integer of 1 to 20, and r represents an integer of 0 to 3.
However, in said Structural Formula (4), n represents the integer of 1-3. X represents a divalent organic group containing a hetero atom. R ³ represents a divalent hydrocarbon group which may have a substituent. R ⁴ represents a monovalent hydrocarbon group which may have a substituent.
<6> The reversible heat-sensitive material according to any one of <1> to <5>, wherein the layer in contact with the support-side surface of the protective layer contains an acrylate compound having either a pentaerythritol group or a dipentaerythritol group. It is a recording medium.
<7> The reversible thermosensitive recording medium according to <6>, wherein the acrylate compound having either a pentaerythritol group or a dipentaerythritol group is an acrylate compound (C) represented by the following structural formula (5). is there.
However, in said structural formula (5), X represents a pentaerythritol group or a dipentaerythritol group. a represents 1 to 5, and b represents 1 to 5.
<8> The content ratio of the acrylate compound (C) is such that the dry mass of the acrylate compound (C) / the dry mass of the layer containing the acrylate compound (C) is 0.01 to 0.10. The reversible thermosensitive recording medium described.
<9> The reversible thermosensitive recording medium according to any one of <6> to <8>, wherein the layer in contact with the support-side surface of the protective layer is a thermosensitive recording layer.
<10> The reversible thermosensitive recording medium according to any one of <6> to <8>, wherein the layer in contact with the support-side surface of the protective layer is an intermediate layer between the thermosensitive recording layer and the protective layer.
<11> The reversible thermosensitive recording medium according to any one of <1> to <10>, further including a heat insulating layer containing at least hollow particles between the thermosensitive recording layer and the support.
<12> The hollow particles have a hollow ratio of 70% or more, the maximum particle diameter (D100) of the hollow particles is 5.0 to 10.0 μm, and the ratio to the 50% frequency particle diameter (D50) ( D100 / D50) is 2.0 to 3.0, and the material forming the hollow particles is a copolymer having at least one of acrylonitrile and methacrylonitrile as a monomer unit. It is a thermal recording medium.
<13> The reversible thermosensitive recording medium according to any one of <1> to <12>, wherein the reversible thermosensitive recording medium is processed into any one of a label shape, a sheet shape, and a roll shape.
<14> The above <1>, which has at least one of irreversible visible information and a printable part on at least a part of at least one of the image forming surface and the opposite surface of the reversible thermosensitive recording medium. To <13>, the reversible thermosensitive recording medium.
<15> The reversible thermosensitive recording medium according to any one of <1> to <14>, having an adhesive layer or a pressure-sensitive adhesive layer on a surface opposite to a surface on which an image is formed. And a reversible thermosensitive recording label.
<16> An information storage unit and a reversible display unit, wherein the reversible display unit includes the reversible thermosensitive recording medium according to any one of <1> to <12>. It is a member.
<17> The information recording unit according to <16>, wherein the information recording unit is any one selected from a magnetic thermosensitive recording layer, a magnetic stripe, an IC memory, an optical memory, a hologram, an RF-ID tag card, a disk, a disk cartridge, and a tape cassette. This is a reversible thermosensitive recording member.
<18> Image forming means for heating the reversible thermosensitive recording medium to form an image on the reversible thermosensitive recording medium, and erasing the image formed on the reversible thermosensitive recording medium by heating the reversible thermosensitive recording medium An image erasing unit that performs the reversible thermosensitive recording medium according to any one of <1> to <14>. Device.
<19> The image processing apparatus according to <18>, wherein the image forming unit is any one of a thermal head and a laser irradiation apparatus.
<20> The image processing according to any one of <18> to <19>, wherein the image erasing unit is any one selected from a thermal head, a ceramic heater, a heat roll, a hot stamp, a heat block, and a laser irradiation device. Device.
<21> An image forming step of heating the reversible thermosensitive recording medium to form an image on the reversible thermosensitive recording medium, and an image formed on the reversible thermosensitive recording medium by heating the reversible thermosensitive recording medium. An image processing method comprising at least one of image erasing steps to be erased, wherein the reversible thermosensitive recording medium is the reversible thermosensitive recording medium according to any one of <1> to <14>. .
<22> The image processing method according to <21>, wherein the image is formed using either a thermal head or a laser irradiation apparatus.
<23> The image may be erased using any one selected from a thermal head, a ceramic heater, a heat roll, a hot stamp, a heat block, and a laser irradiation device. This is an image processing method.
<24> The image processing method according to any one of <22> to <23>, including a step of forming a new image while erasing an image using a thermal head.

The reversible thermosensitive recording medium of the present invention comprises a support, a thermosensitive recording layer on the support, and a protective layer on the thermosensitive recording layer,
The thermosensitive recording layer contains an electron-donating color-forming compound and an electron-accepting compound, and the color tone reversibly changes depending on the temperature,
The protective layer contains a polymer of a composition containing two acrylate compounds selected from an acrylate compound having a pentaerythritol group and an acrylate compound having a dipentaerythritol group. As a result, surface cracks do not occur even when handled like paper, the medium does not curl even when repeated, and the printability, adhesiveness, and transportability of conventional media can be compatible. , Coloring and decoloring can be repeated stably.

  The reversible thermosensitive recording label of the present invention has either an adhesive layer or a pressure-sensitive adhesive layer on the surface opposite to the image forming surface of the reversible thermosensitive recording medium of the present invention. Since the reversible thermosensitive recording label has either the adhesive layer or the pressure-sensitive adhesive layer, a thick substrate such as a card made of vinyl chloride with a magnetic stripe, which is difficult to directly apply the thermosensitive recording layer, and a card size Even large sheet size containers, stickers, large screens, etc. can be applied to a wide range of uses.

  The reversible thermosensitive recording member of the present invention has an information storage unit and a reversible display unit, and the reversible display unit is the reversible thermosensitive recording medium of the present invention. The medium does not curl even if it is repeated, and the printability, adhesiveness, and transportability of the conventional medium can be compatible, and coloring and decoloring can be repeated stably. On the other hand, in the information recording unit, character information, image information is recorded by a recording method corresponding to the type of magnetic thermosensitive recording layer, magnetic stripe, IC memory, optical memory, RF-ID tag card, disk, disk cartridge, tape cassette, hologram, etc. In addition, desired information such as music information and video information is recorded and deleted.

  The image processing apparatus of the present invention includes at least one of an image forming unit for heating the reversible thermosensitive recording medium of the present invention to form an image and an image erasing unit for erasing the image. In the image processing apparatus, the image forming unit heats the reversible thermosensitive recording medium of the present invention to form an image on the reversible thermosensitive recording medium. On the other hand, the image erasing means erases the image formed on the reversible thermosensitive recording medium by heating the reversible thermosensitive recording medium of the present invention. In the present invention, since the reversible thermosensitive recording medium of the present invention is used as the reversible thermosensitive recording medium, surface cracks do not occur even when handled like paper, and the medium curls even when repeated. In addition, the printability, adhesiveness, and transportability of conventional media can be compatible, and repeated color development and decoloration can be performed stably, and rewrite recording with high practicality can be performed.

  In the image processing method of the present invention, the reversible thermosensitive recording medium of the present invention is heated to perform at least one of image formation and image erasure. In the image processing method, the reversible thermosensitive recording medium of the present invention is heated to form an image on the reversible thermosensitive recording medium. On the other hand, the reversible thermosensitive recording medium of the present invention is heated to erase the image formed on the reversible thermosensitive recording medium. In the present invention, since the reversible thermosensitive recording medium of the present invention is used as the reversible thermosensitive recording medium, surface cracks do not occur even when handled like paper, and the medium curls even when repeated. In addition, the printability, adhesiveness, and transportability possessed by conventional media can be compatible, and color development and decoloration can be stably repeated, and an image with a high color density can be formed.

  According to the present invention, conventional problems can be solved, surface cracks do not occur even when handled like paper, the medium does not curl even if it is repeated, and printing provided by conventional media Reversible thermosensitive recording medium that can achieve both colorability, adhesiveness, and transportability, and can stably repeat color development and decoloring, and reversible thermosensitive recording label and reversible thermosensitive recording using the reversible thermosensitive recording medium A member, an image processing apparatus, and an image processing method can be provided.

(Reversible thermosensitive recording medium)
The reversible thermosensitive recording medium of the present invention comprises a support, a thermosensitive recording layer on the support, and a protective layer on the thermosensitive recording layer. Underlayer, intermediate layer, and further if necessary It has other layers.

<Protective layer>
The reversible thermosensitive recording medium that has been proposed so far is widely used as a magnetic thermosensitive card application such as a prepaid card or a point card. In this field, a thermal head and a reversible thermosensitive recording in an image processing apparatus that performs image formation and erasure. Only media interactions have been discussed. However, in fields such as OA applications and parts management and process management applications such as factories, a reversible thermosensitive recording medium, which was never assumed in the conventional card field, is handled like paper. In the conventional protective layer that emphasized the mechanical strength, the protective layer is too hard and cracks occur on the surface of the medium before the repeated printing, and the image deteriorates, and repeated image formation and erasure In this case, a new problem that could not be predicted until now occurred, such as the reversible thermosensitive recording medium curled on the surface of the thermosensitive recording layer.
The mechanism by which cracks occur on the surface of the medium at the time of handling by the operator is because the operator pinches, bends, or folds the reversible thermosensitive recording medium like paper, so that the flexibility of the support is limited. Thus, the flexibility of the protective layer in the outermost layer cannot follow, and a crack is generated on the surface of the protective layer.

  In addition, in order to use a reversible thermosensitive recording medium such as paper, the total thickness of the entire film must be reduced as compared with magnetic thermosensitive card applications such as prepaid cards and point cards. This is because if the thickness of the sheet is large for the operator, it becomes heavier and the work efficiency is reduced. However, since a thin base material is not stiff, reversible thermosensitive recording medium curls on the thermosensitive recording surface side when image formation and erasure are repeated. This mechanism uses a material with a high coating film hardness for the protective layer in order to increase the physical strength with the thermal head by repetition, but in the card field, the base material is thick against the shrinking force of the protective layer. It has a strong power to return and is difficult to curl. However, in fields such as OA applications and parts management and process management applications in factories, the base material is made thinner for workability. It was clarified that the cause is that the shrinking force of the protective layer exceeds the force of the material to return.

  That is, according to the prior art reports on the conventional protective layer design that has been disclosed so far, it has been progressed to harden the protective layer in order to increase the physical strength with the thermal head. I found out that it cannot be handled by the way it is used.

  As a result of intensive studies by the present inventors, it has been possible to solve the problem by giving the protective layer flexibility so as to follow the flexibility of the support. However, a protective layer made of a highly flexible UV curable resin composition can improve cracking and curling, but it has repeated printability, adhesiveness, transportability, and color development and decoloration that the medium has had. It is difficult to achieve both stability.

Therefore, the present inventors have prepared a polymer of an ultraviolet curable resin composition in which the protective layer contains two acrylate compounds selected from an acrylate compound having a pentaerythritol group and an acrylate compound having a dipentaerythritol group. By containing, it is possible to solve a new problem of surface cracks at the time of handling of workers that could not be foreseen until now.
One of the two acrylate compounds is an acrylate compound (A) in which a pentaerythritol group or a dipentaerythritol group and a polymerizable group having an ester bond are directly bonded, and the other is a pentaerythritol group or a dipentaerythritol group. The acrylate compound (B) having a hydrocarbon group which may also have a substituent having an ester bond between the polymerizable group having an ester bond and the polymerizable group having the ester bond has led to further solving the above problems.

The acrylate compound (A) is extremely effective for printability, adhesiveness, transportability, and repeated stability of coloring and decoloring. The acrylate compound (B) has an ester bond that the compound has. The hydrocarbon group which may also have a substituent imparts flexibility to the coating film and is very effective against cracks and curls.
The two acrylate compounds (A) and (B) are preferably compounds represented by the following structural formulas (1) and (2).

In the Structural Formula (1) and (2), X represents a pentaerythritol group or a dipentaerythritol group, Y is _{-CH 2 O -, - CH 2} CH 2 O -, - CH 2 CH 2 CH ₂ O—, —CH ₂ CH ₂ CH ₂ CH ₂ O—, —CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ O—, —CH ₂ CH (CH ₃ ) O—, —CO—CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ O— is represented, Z represents —H, —CO—CH═CH ₂ , a represents 1 to 5, b represents 1 to 5, and c represents 1 to 12.

  The blending mass ratio of the two acrylate compounds (A) and (B) is (A) / (B) = 1.0 / 9.0 to 5.0 / 5.0, so that printability and adhesion are achieved. It has a remarkable effect on the compatibility of cracking and curling, and the stability of colorability, transportability, color development and decoloration. The blending mass ratio of the two types of acrylates (A) and (B) is more preferably (A) / (B) = 1.0 / 9.0 to 5.0 / 5.0, and (A) / (B ) = 1.5 / 8.5 to 4.5 / 5.5, more preferably (A) / (B) = 2.0 / 8.0 to 4.0 / 6.0. If the blending mass ratio of the acrylate compounds (A) and (B) exceeds (A) / (B) = 5.0 / 5.0, sufficient flexibility cannot be given to the coating film, so cracks and curls When the blending mass ratio of the acrylate compounds (A) and (B) is less than (A) / (B) = 1.0 / 9.0, the coating film has sufficient flexibility. However, no effect is obtained on curling, printability, transportability, and repeated stability of coloring and decoloring.

  The total content of the two acrylate compounds in the composition is preferably 50% by mass to 100% by mass, and more preferably 60% by mass to 100% by mass.

  A filler may be added to the protective layer, and the filler can be roughly classified into an inorganic filler and an organic filler. Examples of the inorganic filler include carbonates such as calcium carbonate and magnesium carbonate; silicates such as anhydrous silicic acid, hydrous silicic acid, hydrous aluminum silicate, and hydrous calcium silicate; and hydroxides such as alumina and iron oxide. Materials: zinc oxide, indium oxide, alumina, silica, zirconia, tin oxide, cerium oxide, iron oxide, antimony oxide, barium oxide, calcium oxide, barium oxide, bismuth oxide, nickel oxide, magnesium oxide, chromium oxide, manganese oxide , Metal oxides such as tantalum oxide, niobium oxide, titanium oxide, thorium oxide, hafnium oxide, molybdenum oxide, iron ferrite, nickel ferrite, cobalt ferrite, barium titanate, potassium titanate; such as zinc sulfide, barium sulfate Metal sulfide or sulfate compound Metal carbides such as titanium carbide, silicon carbide, molybdenum carbide, tungsten carbide, tantalum carbide; metal nitrides such as aluminum nitride, silicon nitride, boron nitride, zirconium nitride, vanadium nitride, titanium nitride, niobium nitride, gallium nitride Etc.

  Examples of the organic filler material include silicone resin, cellulose resin, epoxy resin, nylon resin, phenol resin, polyurethane resin, urea resin, melamine resin, polyester resin, polycarbonate resin, polystyrene, polystyrene / isoprene, polystyrene / vinylbenzene, and the like. Styrene resins, vinylidene chloride acrylic, acrylic urethane, acrylic resins such as ethylene acrylic, polyethylene resins, formaldehyde resins such as benzoguanamine formaldehyde, melamine formaldehyde, polymethyl methacrylate resins, vinyl chloride resins, and the like. These can be used alone or in combination of two or more and may be composite particles. Examples of the shape include a spherical shape, a granular shape, a plate shape, and a needle shape.

  Further, a lubricant may be added to the protective layer. Specific examples of the lubricant include synthetic waxes such as ester wax, paraffin wax, polyethylene wax, etc .: vegetable waxes such as hardened castor oil: animals such as beef tallow hardened oil Waxes: Higher alcohols such as stearyl alcohol and behenyl alcohol: Higher fatty acids such as margaric acid, lauric acid, mystynolic acid, palmitic acid, stearic acid, behenic acid, and fumenic acid: higher fatty acid esters such as sorbitan fatty acid ester : Amides such as stearic acid amide, oleic acid amide, lauric acid amide, ethylene bis stearic acid amide, methylene bis stearic acid amide, and methylol stearic acid amide.

The protective layer may contain a release agent and an ultraviolet absorber, and may further contain other components as necessary.
Examples of the release agent include silicone having a polymerizable group, a polymer grafted with silicone, wax, zinc stearate, silicone oil, and the like.
As addition amount of the said mold release agent, 0.01 mass%-50 mass% are preferable with respect to the resin component total mass of the said protective layer, 0.1 mass%-40 mass% are more preferable, 1 mass%- 30 mass% is still more preferable. When the addition amount is less than 0.01% by mass, the effect of addition cannot be obtained, and when the addition amount exceeds 50% by mass, there may be a problem in adhesion to the lower layer.
As said other component, you may contain conventionally well-known surfactant, a leveling agent, an antistatic agent, etc. as an additive.

The solvent used in the protective layer coating liquid, the coating liquid dispersing device, the protective layer coating method, the drying method, the curing method, and the like may be known methods used in the heat-sensitive recording layer described later.
The thickness of the protective layer is preferably 0.1 μm to 20 μm, more preferably 0.5 μm to 10 μm, and even more preferably 1.5 μm to 6 μm. When the thickness is less than 0.1 μm, the protective layer is destroyed when the recorded image is repeatedly erased and printed, and sufficient durability cannot be obtained. The function as a reversible thermosensitive recording medium may be lost, and if the thickness exceeds 20 μm, only blurred images with poor dot reproducibility (fineness of printed images) can be obtained, and heat conduction The energy used for printing and erasing increases due to the problem of the property, and the burden on the apparatus may increase.

In the present invention, the layer in contact with the support-side surface of the protective layer preferably contains an acrylate compound having either a pentaerythritol group or a dipentaerythritol group. Thereby, coexistence of adhesiveness and a crack can be improved further.
Examples of the layer in contact with the support-side surface of the protective layer include a thermal recording layer and an intermediate layer between the thermal recording layer and the protective layer. The heat-sensitive recording layer and the intermediate layer will be described later.

The acrylate compound having either a pentaerythritol group or a dipentaerythritol group is preferably an acrylate compound (C) represented by the following structural formula (5). As a result, the hydroxyl group of the acrylate compound (C) (pentaerythritol group or hydroxyl group portion due to the bond of dipentaerythritol group and hydrogen group) is bonded to the component in the protective layer and increases the interlayer binding force, thereby causing cracks, curls Further, the compatibility of adhesiveness can be further improved.
However, in said structural formula (5), X represents a pentaerythritol group or a dipentaerythritol group. a represents 1 to 5, and b represents 1 to 5.

The content of the acrylate compound (C) is preferably dry mass of the acrylate compound (C) / dry mass of the layer containing the acrylate compound (C) = 0.01 to 0.10. Thereby, there is a remarkable effect for coexistence of crack, curl and adhesiveness.
The content of the acrylate compound (C) is preferably the dry mass of the acrylate compound (C) / the dry mass of the layer containing the acrylate compound (C) = 0.01 to 0.10, preferably 0.01 to 0.0. 08 is more preferable, and 0.01 to 0.07 is still more preferable. When the dry weight of the acrylate compound (C) / the dry weight of the layer containing the acrylate compound (C) is less than 0.01, a remarkable effect cannot be obtained for coexistence of adhesiveness and cracks. If it exceeds, the repeated stability of color development and decoloration may deteriorate.

<Thermal recording layer>
The thermosensitive recording layer contains an electron donating color-forming compound and an electron accepting compound, and the color tone reversibly changes depending on the temperature.
In the present invention, when the thermosensitive recording layer is a layer in contact with the support side surface of the protective layer, it contains either an acrylate compound having a pentaerythritol group or an acrylate compound having a dipentaerythritol group. Specifically, it is preferable that the acrylate compound (C) represented by the structural formula (5) is included.

“The color tone reversibly changes depending on the temperature” in the thermosensitive recording layer means a phenomenon in which a visible change is reversibly caused by a temperature change, and is caused by a difference in heating temperature and cooling rate after heating. It means that a relatively colored state and a decolored state can be formed. In this case, the visible change is divided into a change in color state and a change in shape, but in the present invention, a material that mainly causes a change in color state is used. Changes in the color state include changes in transmittance, reflectance, absorption wavelength, scattering degree, and the like, and an actual reversible thermosensitive recording material displays by combining these changes. More specifically, there is no particular limitation as long as the transparency and color tone are reversibly changed by heat, and it can be appropriately selected according to the purpose. For example, the first specific temperature higher than room temperature is the first. And a second color temperature that is higher than the first specific temperature and then cooled to become the second color state. Among these, those in which the color state changes between the first specific temperature and the second specific temperature are particularly preferable.

  Examples of these include a transparent state at the first specific temperature and a cloudy state at the second specific temperature (Japanese Patent Application Laid-Open No. 55-154198), coloring at the second specific temperature, Those which are decolored at a specific temperature (JP-A-4-224996, JP-A-4-247985, JP-A-4-267190, etc.), become cloudy at the first specific temperature, and at the second specific temperature Those that are in a transparent state (Japanese Patent Laid-Open No. 3-169590, etc.), those that develop black, red, blue, etc. at a first specific temperature and decolorize at a second specific temperature (Japanese Patent Laid-Open No. 2-188293) JP, 2-188294, A) etc. are mentioned.

  The reversible thermosensitive recording medium of the present invention can form a relatively colored state and a decolored state depending on at least one of the heating temperature and the cooling rate after heating. Here, the basic coloring and decoloring phenomenon of the composition comprising the color former and the developer will be described. FIG. 1 shows the relationship between the color density and temperature of this reversible thermosensitive recording medium. When the temperature of the recording medium initially in the decolored state (A) is raised, color development occurs at the temperature T1 at which melting starts, and the molten color state (B) is obtained. When rapidly cooled from the melt color state (B), the color state can be lowered to room temperature and a solid color state (C) is obtained. Whether or not this color development state is obtained depends on the rate of temperature decrease from the molten state, and in slow cooling, the color disappears during the temperature decrease, and the same color disappearance state (A) or rapid color development state (C ) A relatively low concentration state is formed. On the other hand, when the temperature of the rapid color development state (C) is raised again, decoloration occurs at a temperature T2 lower than the color development temperature (D to E), and when the temperature is lowered from here, the same color disappearance state (A) is restored. The actual color developing temperature and color erasing temperature vary depending on the combination of the developer and color former used, and can be selected according to the purpose. Further, the density of the melt coloring state and the coloring density when rapidly cooled are not necessarily the same and may be different.

In the reversible thermosensitive recording medium, the colored state (C) obtained by quenching from the melted state is a state in which the developer and the color former are mixed in a state where they can be contacted with each other, and this is a solid state. Is often formed. This state is a state where the developer and the color former are aggregated to maintain the color development, and it is considered that the color development is stabilized by the formation of this aggregated structure. On the other hand, the decolored state is a state in which both phases are separated. This state is a state in which molecules of at least one compound aggregate to form a domain or crystallize, and a state where the color former and the developer are separated and stabilized by aggregation or crystallization. Conceivable. In many cases, more complete color erasure occurs due to phase separation of the two and crystallization of the developer. In both the decolorization by gradual cooling from the melted state and the decolorization by raising the temperature from the colored state shown in FIG. 1, the aggregation structure changes at this temperature, and phase separation and crystallization of the developer occur.
In the reversible thermosensitive recording medium of the present invention, color recording may be formed by heating to a temperature at which it is once melt-mixed by a thermal head or the like and then rapidly cooling. Further, decolorization is two methods, a method of slowly cooling from a heated state and a method of heating to a temperature slightly lower than the coloring temperature. However, they are the same in the sense that they are phase-separated or at least temporarily held at a temperature at which one crystallizes. The reason for rapid cooling in the formation of the colored state is to prevent the temperature from being maintained at this phase separation temperature or crystallization temperature. The rapid cooling and slow cooling here are relative to one composition, and the boundary thereof changes depending on the combination of the color former and the developer.

-Electron-accepting compound-
The electron-accepting compound (developer) is not particularly limited as long as it can reversibly develop and decolorize using heat as a factor, and can be appropriately selected according to the purpose. (I) a structure having a color developing ability (for example, phenolic hydroxyl group, carboxylic acid group, phosphoric acid group, etc.) that develops an electron donating color developing compound (color former), and (ii) controlling cohesion between molecules. A compound having one or more structures in the molecule selected from the following structures (for example, a structure in which long-chain hydrocarbon groups are linked) is preferable. The linking moiety may be connected to a divalent or higher valent linking group containing a hetero atom, and the long chain hydrocarbon group contains at least one of the same linking group and aromatic group. Also good. Among these, a phenol compound represented by the following structural formula (3) and a phenol compound represented by the following structural formula (4) are particularly preferable.

However, in said structural formula (3), X and Y represent the bivalent organic group containing a hetero atom. R ³ represents a divalent hydrocarbon group which may have a substituent. R ⁴ represents a monovalent hydrocarbon group which may have a substituent. n represents an integer of 1 to 3, m represents an integer of 1 to 20, and r represents an integer of 0 to 3.

However, in said Structural Formula (4), n represents the integer of 1-3. X represents a divalent organic group containing a hetero atom. R ³ represents a divalent hydrocarbon group which may have a substituent. R ⁴ represents a monovalent hydrocarbon group which may have a substituent.

R ³ in the structural formulas (3) and (4) represents a divalent hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a substituent.
Preferred examples of R ³ include those shown below.

However, q, q ′, q ″, and q ′ ″ in the above formulas each represent an integer that satisfies the carbon number of R ³ . Among them, - _{(CH 2) q} - are particularly preferred.

R ⁴ in the structural formulas (3) and (4) represents an aliphatic hydrocarbon group having 1 to 24 carbon atoms which may be substituted with a substituent, and preferably 8 to 18 carbon atoms.
The aliphatic hydrocarbon group may be linear or branched, and may have an unsaturated bond. Examples of the substituent bonded to the hydrocarbon group include a hydroxyl group, a halogen atom, and an alkoxy group. Note that when the sum of carbons of R ³ and R ⁴ is 7 or less, the stability of color development and decoloring properties are lowered, and therefore the number of carbons is preferably 8 or more, and more preferably 11 or more.
Preferred examples of R ⁴ include those shown below.
However, q, q ′, q ″, and q ′ ″ in the above formulas each represent an integer that satisfies the carbon number of R ⁴ . Among these, — (CH ₂ ) _q —CH ₃ is particularly preferable.

X and Y in the structural formulas (3) and (4) represent a divalent organic group containing a hetero atom, and particularly preferably a divalent organic group containing a nitrogen atom or an oxygen atom. It represents a divalent organic group having at least one group represented.

Preferred examples of the divalent organic group include groups represented by the following structural formulas.

Among these, particularly preferable groups include those represented by the following structural formula.

Examples of the phenol compound represented by the structural formula (3) include compounds represented by the following structural formulas (3-1) to (3-4).
However, in the structural formulas (3-1) to (3-4), q, q ′, q ″, and s each independently represent an integer of 0 to 20, and the sum of these integers is 8 or more. is there. Y, Y ′, and Y ″ represent a divalent organic group containing a hetero atom, and these may be the same or different.

  Specific examples of the phenol compound represented by the structural formula (3) include compounds shown in Table 1 below as examples of the structural formula (3-1) and the structural formula (3-2). Although not shown in the structural formula here, in the case of the compounds represented by the structural formulas (3-3) and (3-4), X and Y are the same as those shown in Table 1 below. Take as an example. However, it is not limited to these.

As a phenol compound represented by the said Structural formula (4), either the following structural formula (4-1) and the following structural formula (4-2) is mentioned suitably, for example.
However, m represents 5-11 in the said Structural formula (4-1) and (4-2). n represents 8-22.

  Specific examples of the phenol compound represented by the structural formula (4-1) and the structural formula (4-2) are shown below.

-Electron donating color compound-
There is no restriction | limiting in particular as said electron donating coloring compound (color former), According to the objective, it can select suitably, For example, a leuco dye etc. are mentioned suitably.
The leuco dye is preferably a fluorane compound or an azaphthalide compound, such as 2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-di (n-butylamino) fluorane. 2-anilino-3-methyl-6- (Nn-propyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (N-isopropyl-N-methylamino) fluorane, 2-anilino -3-methyl-6- (N-isobutyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (Nn-amyl-N-methylamino) fluorane, 2-anilino-3-methyl -6- (N-sec-butyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (Nn-amyl-N-ethylamino) Luolan, 2-anilino-3-methyl-6- (N-iso-amyl-N-ethylamino) fluorane, 2-anilino-3-methyl-6- (Nn-propyl-N-isopropylamino) fluorane, 2-anilino-3-methyl-6- (N-cyclohexyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (N-ethyl-p-toluidino) fluorane, 2-anilino-3-methyl -6- (N-methyl-p-toluidino) fluorane, 2- (m-trichloromethylanilino) -3-methyl-6-diethylaminofluorane, 2- (m-trifluoromethylanilino) -3-methyl -6-diethylaminofluorane, 2- (m-trichloromethylanilino) -3-methyl-6- (N-cyclohexyl-N-methylamino) fluor Lan, 2- (2,4-dimethylanilino) -3-methyl-6-diethylaminofluorane, 2- (N-ethyl-p-toluidino) -3-methyl-6- (N-ethylanilino) fluorane, 2 -(N-ethyl-p-toluidino) -3-methyl-6- (N-propyl-p-toluidino) fluorane, 2-anilino-6- (Nn-hexyl-N-ethylamino) fluorane, 2- (O-chloroanilino) -6-diethylaminofluorane, 2- (o-chloroanilino) -6-dibutylaminofluorane, 2- (m-trifluoromethylanilino) -6-diethylaminofluorane, 2,3-dimethyl -6-dimethylaminofluorane, 3-methyl-6- (N-ethyl-p-toluidino) fluorane, 2-chloro-6-diethylaminofluorane, 2 -Bromo-6-diethylaminofluorane, 2-chloro-6-dipropylaminofluorane, 3-chloro-6-cyclohexylaminofluorane, 3-bromo-6-cyclohexylaminofluorane, 2-chloro-6- ( N-ethyl-N-isoamylamino) fluorane, 2-chloro-3-methyl-6-diethylaminofluorane, 2-anilino-3-chloro-6-diethylaminofluorane, 2- (o-chloroanilino) -3-chloro -6-cyclohexylaminofluorane, 2- (m-trifluoromethylanilino) -3-chloro-6-diethylaminofluorane, 2- (2,3-dichloroanilino) -3-chloro-6-diethylaminofluor Oran, 1,2-benzo-6-diethylaminofluorane, 3-diethylamino-6- (m-tri (Loromethylanilino) fluorane, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-) Methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-octyl-2-methylindol-3-yl) -3- (2-ethoxy-4) -Diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-methyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl- 2-Methylindol-3-yl) -3- (2-methyl-4-diethylaminophenyl) -7-azaphthalide, 3- (1-ethyl-2-methylindo) Ru-3-yl) -3- (4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-Nn-amyl-N- Methylaminophenyl) -4-azaphthalide, 3- (1-methyl-2-methylindol-3-yl) -3- (2-hexyloxy-4-diethylaminophenyl) -4-azaphthalide, 3,3-bis ( 2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3,3-bis (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, and the like.

In addition to the fluorane compound and the azaphthalide compound, conventionally known leuco dyes can be used as the electron donating color forming compound (color former). For example, 2- (p-acetylanilino) -6- (Nn-amyl-Nn-butylamino) fluorane, 2-benzylamino-6- (N-ethyl-p-toluidino) fluorane, 2-benzylamino-6- (N-methyl-2 , 4-dimethylanilino) fluorane, 2-benzylamino-6- (N-ethyl-2,4-dimethylanilino) fluorane, 2-benzylamino-6- (N-methyl-p-toluidino) fluorane, -Benzylamino-6- (N-ethyl-p-toluidino) fluorane, 2- (di-p-methylbenzylamino) -6- (N-ethyl-p-toluidino) fluora 2- (α-phenylethylamino) -6- (N-ethyl-p-toluidino) fluorane, 2-methylamino-6- (N-methylanilino) fluorane, 2-methylamino-6- (N-ethylanilino) Fluorane, 2-methylamino-6- (N-propylanilino) fluorane, 2-ethylamino-6- (N-methyl-p-toluidino) fluorane, 2-methylamino-6- (N-methyl-2, 4-dimethylanilino) fluorane, 2-ethylamino-6- (N-ethyl-2,4-dimethylanilino) fluorane, 2-dimethylamino-6- (N-methylanilino) fluorane, 2-dimethylamino-6 -(N-ethylanilino) fluorane, 2-diethylamino-6- (N-methyl-p-toluidino) fluorane, 2-diethylamino- 6- (N-ethyl-p-toluidino) fluorane, 2-dipropylamino-6- (N-methylanilino) fluorane, 2-dipropylamino-6- (N-ethylanilino) fluorane, 2-amino-6- ( N-methylanilino) fluorane, 2-amino-6- (N-ethylanilino) fluorane, 2-amino-6- (N-propylanilino) fluorane, 2-amino-6- (N-methyl-p-toluidino) fluorane 2-amino-6- (N-ethyl-p-toluidino) fluorane, 2-amino-6- (N-propyl-p-toluidino) fluorane, 2-amino-6- (N-methyl-p-ethylanilino) Fluorane, 2-amino-6- (N-ethyl-p-ethylanilino) fluorane, 2-amino-6- (N-propyl-p-ethylanily) ) Fluorane, 2-amino-6- (N-methyl-2,4-dimethylanilino) fluorane, 2-amino-6- (N-ethyl-2,4-dimethylanilino) fluorane, 2-amino-6 -(N-propyl-2,4-dimethylanilino) fluorane, 2-amino-6- (N-methyl-p-chloroanilino) fluorane, 2-amino-6- (N-ethyl-p-chloroanilino) fluorane, 2-amino-6- (N-propyl-p-chloroanilino) fluorane, 1,2-benzo-6- (N-ethyl-N-isoamylamino) fluorane, 1,2-benzo-6-dibutylaminofluorane, 1,2-benzo-6- (N-methyl-N-cyclohexylamino) fluorane, 1,2-benzo-6- (N-ethyl-N-toluidino) fluorane, etc. It is.
These may be used individually by 1 type and may use 2 or more types together. Multi-color and full-color can also be achieved by laminating layers that develop colors having different colors.

  The mixing ratio of the electron-donating color-forming compound (color former) and the electron-accepting compound (developer) varies depending on the combination of the compounds used, and cannot be specified unconditionally. The developer is preferably from 0.1 to 20, and more preferably from 0.2 to 10. If the amount of the developer is less or more than this range, the density of the colored state may be lowered, which may be a problem. In addition, the color former and the developer can be used in a microcapsule.

-Discoloration accelerator-
In the present invention, by using the developer and a compound having at least one amide group, urethane group, and urea group in the molecule as the color erasure accelerator, the color erasure is promoted in the process of forming the erased state. An intermolecular interaction is induced between the agent and the developer, and the erasing speed can be remarkably increased.

  The decoloring accelerator may be a compound having at least one selected from an amide group, a urethane group, and a urea group in the molecule, and among these, the following structural formulas (5) to (11) The compounds represented are particularly preferred.

R ⁵ —NHCO—R ^6. Structural formula (5)
^{R 5 -NHCO-R 7 -CONH-} R 6 ··· structural formula (6)
^{R 5 -CONH-R 7 -NHCO-} R 6 ··· structural formula (7)
^{R 5 -NHCOO-R} 6 ··· structural formula (8)
R < ⁵ > -NHCOO-R < ⁷ > -OCONH-R < ⁶ > ... Structural formula (9)
R ⁵ —OCONH—R ⁷ —NHCOO—R ^6. Structural formula (10)
In the Structural Formula ^{(5) ~ (11),} R 5, R 6, and ^{R 8} represents a straight-chain alkyl group having 7 to 22 carbon atoms, branched alkyl groups, unsaturated alkyl groups. R ⁷ represents a divalent organic group having 1 to 10 carbon atoms. R ⁹ represents a trivalent functional group having 4 to 10 carbon atoms.

Examples of R ⁵ , R ⁶ , and R ⁸ include a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a stearyl group, a behenyl group, and an oleyl group.
Examples of R ⁶ include a methylene group, an ethylene group, a propylene group, a butylene group, a heptamethylene group, a hexamethylene group, an octamethylene group, a —C ₃ H ₆ OC ₃ H ₆ — group, and —C ₂ H ₄ OC _2. H ₄ - _{group, -C 2 H 4 OC 2 H} 4 OC 2 H 4 - group, and the like.
Preferred examples of R ⁹ include those represented by the following structural formulas.

  Specific examples of the compounds represented by the structural formula (5) to the structural formula (11) include compounds represented by the following (1) to (81).

(1) C ₁₁ H ₂₃ CONHC ₁₂ H ₂₅ ,
(2) C ₁₅ H ₃₁ CONHC ₁₆ H ₃₃ ,
(3) C ₁₇ H ₃₅ CONHC ₁₈ H ₃₇ ,
(4) C ₁₇ H ₃₅ CONHC ₁₈ H ₃₅ ,
(5) C ₂₁ H ₄₁ CONHC ₁₈ H ₃₇ ,
(6) C ₁₅ H ₃₁ CONHC ₁₈ H ₃₇ ,
(7) C ₁₇ H ₃₅ CONHCH ₂ NHCOC ₁₇ H ₃₅ ,
(8) C ₁₁ H ₂₃ CONHCH ₂ NHCOC ₁₁ H ₂₃ ,
_{(9) C 7 H 15 CONHC} 2 H 4 NHCOC 17 H 35,
(10) C ₉ H ₁₉ CONHC ₂ H ₄ NHCOC ₉ H ₁₉ ,
(11) C ₁₁ H ₂₃ CONHC ₂ H ₄ NHCOC ₁₁ H ₂₃ ,
(12) C ₁₇ H ₃₅ CONHC ₂ H ₄ NHCOC ₁₇ H ₃₅ ,
_{(13) (CH 3) 2} CHC 14 H 35 CONHC 2 H 4 NHCOC 14 H 35 (CH 3) 2,
(14) C ₂₁ H ₄₃ CONHC ₂ H ₄ NHCOC ₂₁ H ₄₃ ,
(15) C ₁₇ H ₃₅ CONHC ₆ H ₁₂ NHCOC ₁₇ H ₃₅ ,
(16) C ₂₁ H ₄₃ CONHC ₆ H ₁₂ NHCOC ₂₁ H ₄₃ ,
(17) C ₁₇ H ₃₃ CONHCH ₂ NHCOC ₁₇ H ₃₃ ,
_{(18) C 17 H 33 CONHC} 2 H 4 NHCOC 17 H 33,
(19) C ₂₁ H ₄₁ CONHC ₂ H ₄ NHCOC ₂₁ H ₄₁ ,
_{(20) C 17 H 33 CONHC} 6 H 12 NHCOC 17 H 33,
(21) C ₈ H ₁₇ NHCOC ₂ H ₄ CONHC ₁₈ H ₃₇ ,
(22) C ₁₀ H ₂₁ NHCOC ₂ H ₄ CONHC ₁₀ H ₂₁ ,
(23) C ₁₂ H ₂₅ NHCOC ₂ H ₄ CONHC ₁₂ H ₂₅ ,
(24) C ₁₈ H ₃₇ NHCOC ₂ H ₄ CONHC ₁₈ H ₃₇ ,
(25) C ₂₁ H ₄₃ NHCOC ₂ H ₄ CONHC ₂₁ H ₄₃ ,
_{(26) C 18 H 37 NHCOC} 6 H 12 CONHC 18 H 37,
_{(27) C 18 H 35 NHCOC} 4 H 8 CONHC 18 H 35,
_{(28) C 18 H 35 NHCOC} 8 H 16 CONHC 18 H 35,
(29) C ₁₂ H ₂₅ OCONHC ₁₈ H ₃₇ ,
(30) C ₁₃ H ₂₇ OCONHC ₁₈ H ₃₇ ,
(31) C ₁₆ H ₃₃ OCONHC ₁₈ H ₃₇ ,
(32) C ₁₈ H ₃₇ OCONHC ₁₈ H ₃₇ ,
(33) C ₂₁ H ₄₃ OCONHC ₁₈ H _37,
(34) C ₁₂ H ₂₅ OCONHC ₁₆ H ₃₃ ,
(35) C ₁₃ H ₂₇ OCONHC ₁₆ H ₃₃ ,
(36) C ₁₆ H ₃₃ OCONHC ₁₆ H ₃₃ ,
(37) C ₁₈ H ₃₇ OCONHC ₁₆ H ₃₃ ,
(38) C ₂₁ H ₄₃ OCONHC ₁₆ H ₃₃ ,
(39) C ₁₂ H ₂₅ OCONHC ₁₄ H ₂₉ ,
(40) C ₁₃ H ₂₇ OCONHC ₁₄ H ₂₉ ,
(41) C ₁₆ H ₃₃ OCONHC ₁₄ H ₂₉ ,
(42) C ₁₈ H ₃₇ OCONHC ₁₄ H ₂₉ ,
(43) C ₂₂ H ₄₅ OCONHC ₁₄ H ₂₉ ,
(44) C ₁₂ H ₂₅ OCONHC ₁₂ H ₃₇ ,
(45) C ₁₃ H ₂₇ OCONHC ₁₂ H ₃₇ ,
(46) C ₁₆ H ₃₃ OCONHC ₁₂ H ₃₇ ,
(47) C ₁₈ H ₃₇ OCONHC ₁₂ H ₃₇ ,
(48) C ₂₁ H ₄₃ OCONHC ₁₂ H ₃₇ ,
(49) C ₂₂ H ₄₅ OCONHC ₁₈ H ₃₇ ,
(50) C ₁₈ H ₃₇ NHCOOC ₂ H ₄ OCONHC ₁₈ H ₃₇ ,
(51) C ₁₈ H ₃₇ NHCOOC ₃ H ₆ OCONHC ₁₈ H ₃₇ ,
(52) C ₁₈ H ₃₇ NHCOOC ₄ H ₈ OCONHC ₁₈ H ₃₇ ,
(53) C ₁₈ H ₃₇ NHCOOC ₆ H ₁₂ OCONHC ₁₈ H ₃₇ ,
(54) C ₁₈ H ₃₇ NHCOOC ₈ H ₁₆ OCONHC ₁₈ H ₃₇ ,
(55) C ₁₈ H ₃₇ NHCOOC ₂ H ₄ OC ₂ H ₄ OCONHC ₁₈ H ₃₇ ,
(56) C ₁₈ H ₃₇ NHCOOC ₃ H ₆ OC ₃ H ₆ OCONHC ₁₈ H ₃₇ ,
(57) C ₁₈ H ₃₇ NHCOOC ₁₂ H ₂₄ OCONHC ₁₈ H ₃₇ ,
(58) C ₁₈ H ₃₇ NHCOOC ₂ H ₄ OC ₂ H ₄ OC ₂ H ₄ OCONHC ₁₈ H ₃₇ ,
(59) C ₁₆ H ₃₃ NHCOOC ₂ H ₄ OCONHC ₁₆ H ₃₃ ,
(60) C ₁₆ H ₃₃ NHCOOC ₃ H ₆ OCONHC ₁₆ H ₃₃ ,
(61) C ₁₆ H ₃₃ NHCOOC ₄ H ₈ OCONHC ₁₆ H ₃₃ ,
(62) C ₁₆ H ₃₃ NHCOOC ₆ H ₁₂ OCONHC ₁₆ H ₃₃ ,
(63) C ₁₆ H ₃₃ NHCOOC ₈ H ₁₆ OCONHC ₁₆ H ₃₃ ,
(64) C ₁₈ H ₃₇ OCOHNC ₆ H ₁₂ NHCOOC ₁₈ H ₃₇ ,
(65) C ₁₆ H ₃₃ OCOHNC ₆ H ₁₂ NHCOOC ₁₆ H ₃₃ ,
_{(66) C 14 H 29 OCOHNC} 6 H 12 NHCOOC 14 H 29,
_{(67) C 12 H 25 OCOHNC} 6 H 12 NHCOOC 12 H 25,
_{(68) C 10 H 21 OCOHNC} 6 H 12 NHCOOC 10 H 21,
_{(69) C 8 H 17 OCOHNC} 6 H 12 NHCOOC 8 H 17,

  The addition amount of the decoloring accelerator is preferably 0.1 part by mass to 300 parts by mass, and more preferably 3 parts by mass to 100 parts by mass with respect to 100 parts by mass of the developer. When the addition amount is less than 0.1 parts by mass, the effect of adding a decoloring accelerator may not be exhibited. When the addition amount exceeds 300 parts by mass, the color density may decrease.

  In addition to the above components, the heat-sensitive recording layer may contain a binder resin and, if necessary, various additives for improving and controlling the coating characteristics and color-decoloring / decoloring characteristics of the heat-sensitive recording layer. Examples of the additive include a crosslinking agent, a crosslinking accelerator, a filler, a lubricant, a surfactant, a conductive agent, a filler, an antioxidant, a light stabilizer, a color stabilizer, and a plasticizer.

The binder resin is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride vinyl acetate copolymer, ethyl cellulose, polystyrene resin, and styrene copolymer. Polymer, phenoxy resin, polyester resin, aromatic polyester resin, polyurethane resin, polycarbonate resin, polyacrylate resin, polymethacrylate resin, acrylic copolymer, maleic acid copolymer, polyvinyl alcohol resin, modified Examples thereof include polyvinyl alcohol resin, hydroxyethyl cellulose, carboxymethyl cellulose, starches, and the like.
The role of these binder resins is to keep each material of the composition uniformly dispersed without being displaced by the application of heat for recording and erasing. Therefore, it is preferable to use a resin having high heat resistance as the binder resin. Further, as the binder resin, it is preferable to use a curable resin to which a cross-linking agent is added and which can be cross-linked by, for example, heat, ultraviolet light, electron beam or the like (hereinafter, sometimes referred to as “resin in a cross-linked state”). ). By containing a curable resin in the thermosensitive recording layer, the heat resistance and the coating strength of the thermosensitive recording layer are improved, and the repeated durability of the reversible thermosensitive recording medium is improved.

The curable resin is not particularly limited and may be appropriately selected depending on the intended purpose.For example, acrylic polyol resin, polyester polyol resin, polyurethane polyol resin, phenoxy resin, polyvinyl butyral resin, cellulose acetate propionate, Examples thereof include a resin having a group that reacts with a crosslinking agent such as cellulose acetate butyrate, or a resin obtained by copolymerizing a monomer having a group that reacts with a crosslinking agent and another monomer.
Among these, acrylic polyol resin, polyester polyol resin, and polyurethane polyol resin are particularly preferable.
Further, the hydroxyl value of the curable resin is preferably 70 KOHmg / g or more, more preferably 90 KOHmg / g or more, from the viewpoint of improving durability, coating surface hardness and crack resistance. The magnitude of the hydroxyl value affects the crosslink density, and thus affects the chemical resistance and physical properties of the coating film.

  The acrylic polyol resin uses a (meth) acrylic acid ester monomer, an unsaturated monomer having a carboxylic acid group, an unsaturated monomer having a hydroxyl group, and other ethylenically unsaturated monomers. It can be synthesized according to a known solution polymerization method, suspension polymerization method, emulsion polymerization method and the like. Examples of the unsaturated monomer having a hydroxyl group include hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), 2-hydroxyethyl methacrylate (HEMA), 2-hydroxypropyl methacrylate (HPMA), and 2-hydroxybutyl. Examples include monoacrylate (2-HBA) and 1,4-hydroxybutyl monoacrylate (1-HBA). Among these, the use of a monomer having a primary hydroxyl group is more resistant to cracking of the coating film. 2-Hydroxyethyl methacrylate is particularly preferred because of its good durability.

  There is no restriction | limiting in particular as said crosslinking agent, According to the objective, it can select suitably from conventionally well-known isocyanate type compounds, amines, phenols, an epoxy compound, etc. Of these, isocyanate compounds are particularly suitable.

The isocyanate compound is not particularly limited and may be appropriately selected from known compounds depending on the purpose. For example, urethane-modified isocyanate, allophanate-modified, isocyanurate-modified, and burette-modified isocyanate monomers. Body, carbodiimide modified body, modified body such as blocked isocyanate, and the like. Examples of the isocyanate monomer that forms the modified product include tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), naphthylene diisocyanate (NDI), para Phenylene diisocyanate (PPDI), tetramethylxylylene diisocyanate (TMXDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI), lysine diisocyanate (LDI), isopropylidenebis (4-cyclohexylisocyanate) ) (IPC), cyclohexyl diisocyanate (CHDI), tolidine diisocyanate (TODI) and the like.
A catalyst used in this kind of reaction may be used as the crosslinking accelerator. Examples of the crosslinking accelerator include tertiary amines such as 1,4-diaza-bicyclo [2,2,2] octane, and metal compounds such as organic tin compounds. The total amount of the crosslinking agent added may or may not undergo a crosslinking reaction. That is, an unreacted crosslinking agent may be present. Since this type of cross-linking reaction proceeds over time, the presence of an unreacted cross-linking agent does not indicate that the cross-linking reaction has not proceeded at all, but an unreacted cross-linking agent is detected. However, this does not mean that there is no resin in a crosslinked state. Further, as a method for distinguishing whether a polymer is in a crosslinked state or in a non-crosslinked state, it can be distinguished by immersing the coating film in a highly soluble solvent. That is, the polymer in the non-crosslinked state dissolves in the solvent and does not remain in the solute, so the presence or absence of the polymer structure of the solute may be analyzed. Therefore, if the presence of a polymer structure in the solute cannot be confirmed, it can be said that the polymer is in a non-crosslinked state, and can be distinguished from a crosslinked polymer. Here, this can be expressed as a gel fraction.

The gel fraction means the ratio of gel formation when a resin solute in a solvent loses its independent mobility due to interaction and aggregates to form an individualized state (gel). The resin preferably has a gel fraction of 30% or more, more preferably 50% or more, still more preferably 70% or more, and particularly preferably 80% or more. If the gel fraction is small, the durability is reduced repeatedly. To improve the gel fraction, a curable resin that is cured by heat, ultraviolet irradiation (UV), electron beam irradiation (EB), etc. is mixed in the resin. Or the resin itself may be cross-linked.
Here, as the method for measuring the gel fraction, the membrane is peeled off from the support and the initial mass of the membrane is measured, and then the membrane is sandwiched between 400 mesh wire nets in a solvent in which the resin before crosslinking is soluble. It can be soaked for 24 hours and then vacuum dried to measure the mass after drying.
The said gel fraction can be calculated | required by following Numerical formula 1.

When calculating the gel fraction by this calculation, the calculation is performed excluding the mass of organic low-molecular substance particles other than the resin component in the thermosensitive recording layer. At this time, when the mass of the organic low molecular weight substance is not known in advance, the area ratio per unit area, the resin and the organic low molecular weight substance are observed by cross-sectional observation using a transmission electron microscope (TEM), a scanning electron microscope (SEM) or the like. The gel fraction value may be calculated by calculating the mass ratio based on the specific gravity of each, calculating the mass of the organic low molecular weight substance.
Further, in the case of the measurement, a thermosensitive recording layer is provided on the support and another layer such as a protective layer is laminated thereon, or other layers are provided between the support and the thermosensitive recording layer. When there is a layer, first, the thickness of the thermosensitive recording layer and other layers is measured by cross-sectional observation of the transmission electron microscope (TEM), scanning electron microscope (SEM), etc. And the surface of the heat-sensitive recording layer is exposed, the heat-sensitive recording layer is peeled off, and the gel fraction is measured in the same manner as in the measurement method.

Further, in the method for measuring the gel fraction, when there is a protective layer made of an ultraviolet curable resin or the like in the upper layer of the thermosensitive recording layer, in order to prevent the protective layer and the like from being mixed as much as possible, It is necessary to cut the surface of the heat-sensitive recording layer slightly to prevent the influence on the gel fraction value.
In the recording layer, one kind of inorganic filler and / or organic filler described in the protective layer may be used alone, or two or more kinds may be used in combination. In the case of a plurality, there are no particular limitations on how to combine the inorganic filler and the organic filler. Examples of the shape include a spherical shape, a granular shape, a plate shape, and a needle shape.

The filler content is preferably 5% by volume to 50% by volume in terms of volume fraction.
There is no restriction | limiting in particular as said lubricant, It can select suitably according to the objective from well-known things, For example, synthetic waxes, such as ester wax, paraffin wax, and polyethylene wax; Vegetable waxes, such as hardened castor oil Animal waxes such as beef tallow oil; higher alcohols such as stearyl alcohol and behenyl alcohol; higher fatty acids such as margaric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid; fatty acid esters of sorbitan, etc. Higher fatty acid esters; amides such as stearic acid amide, oleic acid amide, lauric acid amide, ethylene bis stearic acid amide, methylene bis stearic acid amide, and methylol stearic acid amide;
The content of the lubricant in the heat-sensitive recording layer is preferably from 0.1% to 95% by volume, more preferably from 1% to 75% by volume.

  The surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant. Can be mentioned.

  The plasticizer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include phosphate ester, fatty acid ester, phthalate ester, dibasic acid ester, glycol, polyester plasticizer, and epoxy plasticizer. Agents, etc.

  The method for forming the thermosensitive recording layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, (1) the binder resin, the electron donating color compound, and the electron accepting compound A method in which a heat-sensitive recording layer coating solution in which a solvent is dissolved or dispersed in a solvent is coated on a support, and the solvent is evaporated to form a sheet or the like, or at the same time or thereafter, (2) only the binder resin A thermosensitive recording layer coating solution in which the electron-donating color-forming compound and the electron-accepting compound are dispersed in a solvent in which is dissolved, and the solvent is evaporated to form a sheet or the like at the same time or thereafter (3) Without using a solvent, the binder resin, the electron-donating color-forming compound, and the electron-accepting compound are heated and melted and mixed with each other, and this molten mixture is sheet-like. Method of crosslinking after molding to cool, and the like. In these, it is also possible to form a sheet-like reversible thermosensitive recording medium without using the support.

The solvent used in (1) or (2) varies depending on the type of the binder resin, the electron-donating color compound, and the electron-accepting compound, and cannot be specified unconditionally. , Methyl ethyl ketone, methyl isobutyl ketone, chloroform, carbon tetrachloride, ethanol, toluene, benzene, and the like.
The electron-accepting compound is dispersed in the form of particles in the heat-sensitive recording layer.

Various pigments, antifoaming agents, pigments, dispersants, slip agents, preservatives, crosslinking agents, plasticizers, and the like are added to the thermal recording layer coating solution for the purpose of developing high performance as a coating material. May be.
The method for applying the heat-sensitive recording layer is not particularly limited and may be appropriately selected depending on the intended purpose. The support may be continuously rolled or cut into a sheet shape, For example, blade coating, wire bar coating, spray coating, air knife coating, bead coating, curtain coating, gravure coating, kiss coating, reverse roll coating, dip coating, die coating, etc. Apply by a known method.

  The drying conditions for the heat-sensitive recording layer coating liquid are not particularly limited and may be appropriately selected depending on the intended purpose. For example, the temperature is from room temperature to 140 ° C. for about 10 minutes to 1 hour.

The resin in the thermosensitive recording layer can be cured by heating, ultraviolet irradiation, electron beam irradiation, or the like.
The ultraviolet irradiation is not particularly limited, and can be performed using a known ultraviolet irradiation apparatus. Examples of the apparatus include a light source, a lamp, a power source, a cooling device, a conveyance device, and the like.
Examples of the light source include a mercury lamp, a metal halide lamp, a gallium lamp, a mercury xenon lamp, and a flash lamp. The wavelength of the light source can be appropriately selected according to the ultraviolet absorption wavelength of the photopolymerization initiator and photopolymerization accelerator added to the reversible thermosensitive recording medium composition.
The conditions for the ultraviolet irradiation are not particularly limited and may be appropriately selected depending on the purpose. For example, the lamp output, the conveyance speed, etc. may be determined according to the irradiation energy necessary for crosslinking the resin. .
The electron beam irradiation can be performed using a known electron beam irradiation apparatus, and the electron beam irradiation apparatus can be roughly classified into two types, a scanning type (scan beam) and a non-scanning type (area beam). Conditions can be selected according to the irradiation area, irradiation dose, and the like. Further, the electron beam irradiation conditions can be determined from the following formula 2 in consideration of the electron flow, the irradiation width, and the conveyance speed in accordance with the dose necessary for crosslinking the resin.

However, in said Numerical formula (2), D represents required dose (Mrad). ΔE / ΔR represents average energy loss. η represents efficiency. I represents the electron current (mA). W represents the irradiation width (cm). V represents a conveyance speed (cm / s).
Industrially, it is preferable to simplify the mathematical formula (2) and use the following mathematical formula (3).

Here, the device rating is represented by Mrad · m / min, and the electron current rating is selected to be about 20 to 500 mA.

The thickness of the thermosensitive recording layer is not particularly limited and may be appropriately selected depending on the purpose. For example, the thickness is preferably 1 μm to 20 μm, and more preferably 3 μm to 15 μm.
If the thickness of the heat-sensitive recording layer is too thin, the color density will be low, so the contrast of the image may be low.If it is too thick, the heat distribution in the layer will be large, and the portion that does not reach the color temperature and does not develop color May occur and the desired color density may not be obtained.

<Support>
The support is not particularly limited in its shape, structure, size and the like, and can be appropriately selected according to the purpose. Examples of the shape include a flat plate shape, May be a single layer structure or a laminated structure, and the size can be appropriately selected according to the size of the reversible thermosensitive recording medium.
Examples of the material for the support include inorganic materials and organic materials. Examples of the inorganic material include glass, quartz, silicon, silicon oxide, aluminum oxide, SiO ₂ and metal. Examples of the organic material include paper, cellulose derivatives such as cellulose triacetate, synthetic paper, polyethylene terephthalate, polycarbonate, polystyrene, polymethyl methacrylate, and the like. These may be used individually by 1 type and may use 2 or more types together.
Among these, in order to obtain a sheet having 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.
The support is preferably surface-modified by corona discharge treatment, oxidation reaction treatment (chromic acid, etc.), etching treatment, easy adhesion treatment, antistatic treatment, etc. for the purpose of improving the adhesion of the coating layer. Moreover, it is preferable to add a white pigment such as titanium oxide to the support to make it white.
There is no restriction | limiting in particular as thickness of the said support body, It can select suitably according to the objective, 10 micrometers-2,000 micrometers are preferable, 20 micrometers-1,000 micrometers are more preferable, 20 micrometers-300 micrometers are still more preferable, 20 micrometers- 200 μm is particularly preferable.
The support may have a magnetic thermosensitive recording layer on at least one of the same surface and the opposite surface as the thermosensitive recording layer. Further, the reversible thermosensitive recording medium of the present invention can be attached to other media via an adhesive layer or the like.

<Insulation layer>
The heat-insulating layer is used for the purpose of improving the sensitivity by effectively utilizing the applied heat, or for the purpose of improving the adhesion between the support and the heat-sensitive recording layer or preventing the heat-sensitive recording layer material from penetrating into the support. And at least hollow particles, a binder resin, and, if necessary, other components.
Examples of the hollow particles include single hollow particles in which one hollow portion is present in the particles, and multi-hollow particles in which many hollow portions are present in the particles. These may be used individually by 1 type and may use 2 or more types together.
As the binder resin, the same resin as that of the thermosensitive recording layer can be used.
The heat insulating layer can contain at least one of inorganic fillers such as calcium carbonate, magnesium carbonate, titanium oxide, silicon oxide, aluminum hydroxide, kaolin, and talc, and various organic fillers.
In addition, the heat insulating layer may contain a lubricant, a surfactant, a dispersant, and the like.
The thickness of the heat insulating layer is not particularly limited and may be appropriately selected depending on the purpose. It is preferably 0.1 μm to 100 μm, more preferably 1 μm to 80 μm, still more preferably 5 μm to 50 μm, and particularly preferably 5 μm to 40 μm. preferable.

In the present invention, for the expansion of the erasing energy region in the thermal head system, a heat insulating layer containing hollow particles is installed, and the hollow particles have a hollow ratio of 70% or more, and the maximum particle diameter of the hollow particles (D100 ) Is 5.0 μm to 10.0 μm, and at the same time, it is possible to use hollow particles having a ratio (D100 / D50) of 2.0 to 3.0 with a 50% frequency particle diameter (D50). .
Here, the 50% frequency particle size means the particle size when the cumulative percentage reaches 50% when the particle size distribution is expressed in cumulative percentage from the smallest.

  In the present invention, the maximum particle diameter of the hollow particles is preferably 5 μm to 10 μm. When the maximum particle size is larger than 10 μm, when a heat-sensitive recording layer is provided on the heat-insulating layer using these, a large particle portion of the heat-insulating layer forms a portion where the heat-sensitive recording layer is not formed, and a solid image is printed. White spots are likely to occur. On the other hand, when the maximum particle size is smaller than 5 μm, it becomes difficult to ensure a hollow ratio of 70% or more, and as a result, the sensitivity is lowered. Therefore, the maximum particle size of the hollow particles is preferably 5 μm to 10 μm. Further, considering only the increase in the color density, the effect can be obtained if the hollow ratio is 60% or more, but the reversible thermosensitive recording medium has an erasing process. In the erasing method using, the energy used for erasing is extremely small compared to the method using a heat roller, and therefore, the degree of effective utilization of applied energy needs to be increased. Therefore, in order to ensure the erasing density and the erasing energy range in the erasing method using the thermal head, the hollow ratio of the hollow particles used for the heat insulating layer needs to be 70% or more.

  In the present invention, the ratio (D100 / D50) of the 50% frequency particle diameter (D50) and the maximum particle diameter (D100) of the hollow particles is preferably 2.0 to 3.0. This indicates that the particle size distribution is in a broad state, the proportion of fine particles having a particle size of 1 μm or less increases, and the heat insulation layer using these particles has a non-uniform distribution of hollow particles in the layer, resulting in a decrease in sensitivity. cause. On the other hand, when it is less than 2.0, it has a very sharp particle size distribution and is difficult to realize from the viewpoint of synthesis conditions. Therefore, the ratio D100 / D50 of the 50% frequency particle diameter (D50) and the maximum particle diameter (D100) of the hollow particles is preferably 2.0 to 3.0.

  In the present invention, the proportion of hollow particles of 2 μm or less is preferably 5% to 10%, but if it exceeds 10%, the proportion of fine particles having a particle diameter of 1 μm or less increases, and the heat insulating layer using these particles is in the layer. This causes the phenomenon that the distribution of the hollow particles becomes uneven and the sensitivity is lowered. On the other hand, if it is less than 5%, it has a very sharp particle size distribution and is difficult to realize from the viewpoint of synthesis conditions. Accordingly, the proportion of hollow particles of 2 μm or less is preferably 5% to 10%.

  The hollow particles have a hollow ratio of 70% or more, and at the same time, the maximum particle diameter (D100) of the hollow particles is 5.0 μm to 10.0 μm, and at the same time, the ratio D100 to the 50% frequency particle diameter (D50). / D50 is characterized by satisfying 2.0 to 3.0, and hitherto, it has not been known to use a hollow particle satisfying this condition for a reversible thermosensitive recording material. Conventionally, hollow particles used in reversible thermosensitive recording materials require a method of encapsulating a volatile substance in a thermoplastic polymer and volatilizing and foaming in order to achieve a hollowness of 60% or more. Only had hollow particles of 20 μm or more. On the other hand, in order to reduce the particle size, there was a type having a particle size of 1 μm or less by discharging water from particles enclosing water or the like using seed polymerization, but the hollow ratio was only 50% or less. . In the present invention, the hollow ratio is 70% or more from the examination of the shell material, the polymerization method, and the volatile inclusion agent, and the maximum particle diameter (D100) of the hollow particles is 5.0 μm to 10.0 μm. Hollow particles satisfying the ratio D100 / D50 of (D50) of 2.0 to 3.0 can be obtained, and their performance is sequentially determined through repeated trials for the first development in a reversible thermosensitive recording material. As a result of confirmation, a good reversible thermosensitive recording material could be realized.

The glass transition temperature (Tg) of the hollow particles is preferably 95 ° C to 150 ° C, more preferably 95 ° C to 120 ° C. When the Tg is lower than 95 ° C., a heat-insulating layer using these is fused with the heat-sensitive color developing layer during printing by a thermal head, and as a result, sticking occurs and good printing becomes difficult. On the other hand, when the Tg is higher than 150 ° C., the heat insulating layer is in a rigid state at the time of printing with the thermal head and the flexibility is insufficient, so that the phenomenon that the adhesion with the head is lowered and the sensitivity is lowered is recognized. The Tg of the hollow particles is preferably 95 ° C to 150 ° C.
Thus, the heat insulation layer of the reversible thermosensitive recording medium has a hollowness of 70% or more, and the maximum particle size (D100) is preferably 10.0 μm or less, more preferably 5.0 μm to 10.0 μm. The ratio (D100 / D50) of the 50% frequency particle size (D50) to the maximum particle size (D100) is preferably 3.0 or less, more preferably 2.0 to 3.0. Further, the ratio of 2 μm or less is preferably 10% or less, and more preferably 5% to 10%. The glass transition temperature (Tg) is preferably 95 ° C. or higher, and by using hollow particles of 95 ° C. to 150 ° C., heat insulation and head adhesion are improved, and the heat of the thermal head is efficiently reversible thermosensitive recording medium. Since it is transmitted to the surface, high sensitivity is achieved, and the surface of the reversible thermosensitive recording medium is kept uniform, print whitening is prevented, and the uniformity of the printed image is improved.

  The particle size values are all measured using a laser diffraction particle size distribution measuring device (LA-900, manufactured by Horiba, Ltd.). The median diameter is a 50% frequency particle size, denoted as D50, and the maximum particle size is the maximum particle size of the distribution, denoted as D100. The hollowness of the plastic spherical hollow fine particles is a ratio of the outer diameter to the inner diameter of the hollow particles, and is expressed by the following formula.

  Said Tg is a glass transition temperature and represents Tg of the resin component of a hollow particle. In this, a solid is formed of the same resin as the resin component of the hollow particles, and the glass transition (Tg) of the solid is measured by a usual method (DSC, DTA, TMA, etc.).

  In the present invention, since the hollow particles act as a heat insulating material and have elasticity, the thermal energy from the thermal head is efficiently used to improve the color development sensitivity. In terms of sensitivity, the hollowness is preferably 70% or more, more preferably 75% to 98%, and still more preferably 85% to 95%. When the hollow ratio is less than 70%, the above-described effect is reduced, and when the hollow ratio exceeds 98%, the film thickness becomes thin and the strength may be lowered.

  Various methods for producing the hollow particles have been proposed. As a method for producing the hollow particles of the present invention, a volatile substance is included as the core material of the polymer, the outer layer is made of a thermoplastic polymer, and is formed by volatile foaming. The method used is usually used. Specific examples of the method include those disclosed in WO99 / 46320 and JP2000-24488. In this method, it is a requirement that the permeability of the shell material is low in order to set the hollow ratio to 70% or more during heating and foaming. Conventional polymers containing vinylidene chloride have low permeability but have environmental problems. Accordingly, the present inventors can use a crosslinked vinyl polymer instead of vinylidene chloride as a shell material for hollow particles having low permeability, thereby reducing the permeability and increasing the hollow ratio to 70% or more.

  Examples of the vinyl polymer include monomers having a carboxylic acid such as acrylic acid ester, ethylene, propylene, vinyl acetate, styrene, acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, succinic acid, and itaconic acid in the molecule; magnesium acrylate , Carboxylic acid metal salts such as calcium acrylate, zinc acrylate, magnesium methacrylate, calcium methacrylate, zinc methacrylate; N-methylol acrylamide, N-methylol having a carboxylic acid-reactive group in the molecule Methacrylamide, glycidyl acrylate, glycidyl methacrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydro Ci-3-phenoxypropyl acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl methacrylate, magnesium monoacrylate, zinc monoacrylate, etc .; acrylamide, methacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, methyl methacrylate, t-butyl methacrylate, isobornyl (meth) acrylate, cyclohexyl methacrylate, benzyl methacrylate, N-vinylpyrrolidone, styrene, N-phenylmaleimide, N-naphthylmaleimide, N -Cyclohexylmaleimide, methylmaleimide and the like.

  The hollow particles need to have a high hollow ratio and a thin shell. When the shell becomes thin, the strength against pressure or the like is weakened and the shell is easily broken. On the other hand, if the shell is simply hardened to give strength, it tends to become brittle and is easily broken by bending. Therefore, a balance between hardness and flexibility is necessary for the shell material, and acrylonitrile and methacrylonitrile are listed as preferable shell materials having both hardness and flexibility. However, the hollow particles having the particle diameter and the hollow ratio can be realized only by the specific shell material, polymerization method, and volatile inclusion agent, and can be realized by other means.

The hollow particles can also form a crosslinked structure. A material for forming a crosslinked structure, that is, a crosslinking agent, can be achieved by copolymerizing a monomer having two or more functionalities together with the vinyl monomer. Also suitable are vinyl monomers or divinylbenzene having two or more vinyl groups per molecule.
Examples of the crosslinkable monomer include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1.6-hexanediol di (Meth) acrylate, trimethylolpropane tri (meth) acrylate, glycerin di (meth) acrylate, triethylene glycol di (meth) acrylate, PEG # 200 di (meth) acrylate, PEG # 400 di (meth) acrylate, PEG # 600 di (meth) acrylate, 1,3-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, pentaerythritol tri ( Acrylate), pentaerythritol tetra (meth) acrylate, pentaerythritol hexa (meth) acrylate 3-acryloyloxyglycerin monoacrylate, dimethylol tricyclodecane di (meth) acrylate, triallyl formal tri (meth) acrylate, polyethylene glycol Dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2'-bis (4-acryloxydiethoxyphenyl) propane, trimethylolpropane trimethacrylate, diaryl phthalate, divinyl A general crosslinking monomer such as benzene can be used. As the crosslinkable monomer, a monomer that does not contain a halogen atom such as a chlorine atom is used, and in order to make the maximum particle size of the hollow particles 10 μm or less, the particle size distribution of the formed hollow particles is sharp. For this purpose, the copolymer containing the acrylic monomer represented by the formula (1) has a characteristic that the particle size distribution of the particles becomes sharp, and has an excellent effect in this respect. Show. The terminal of the crossed bond of norbornane which is the left ring of the formula (1) is hydrogen, but may be a methyl group. The amount of the crosslinking agent used in the present invention is preferably about 0.1% to 10% in the monomer.

In producing actual microcapsules, conventional methods for producing foamable microcapsules are generally used. That is, a colloidal silica gel is used as the aqueous dispersant. A water-soluble polymer compound is used as an auxiliary dispersant.
As the water-soluble polymer, amphoteric or cationic water-soluble polymers such as diethanolamine adipic acid condensate, polyethyleneimine, and polyvinylpyrrolidone polymers are used.

In the present invention, an inorganic metal salt is used in order to use a large amount of a water-soluble monomer. As the water-soluble metal salt, a compound that dissolves in water in a neutral or acidic region such as sodium chloride, magnesium chloride, or sodium sulfate is used.
The amount used is a concentration from the saturation amount to the aqueous mixture to (saturation amount -5%). The mixture is adjusted to pH 3 to 5 to make an aqueous system.

  The oil phase is used by mixing it uniformly. The above-mentioned monomer mixture having a radical reactive unsaturated double bond, a solvent mixture having a boiling point suitable for synthesis, and a radical initiator mixture are used as the oil phase. As the solvent, an organic solvent having a boiling point equal to or lower than the temperature suitable for synthesis is used, but any solvent that does not dissolve in the outer wall polymer and has high foaming efficiency can be used. Hydrocarbon solvents in the 200 ° C. range are suitable for use. For example, n-hexane, isohexane, n-heptane, n-octane, isooctane, n-decane, isodecane, and other petroleum fractionation components are used in a timely manner. However, when a relatively low boiling point solvent is used, the foaming start temperature number decreases. Tend to.

  As said radical initiator, 2 or more types are mixed and used. It is preferable to use two or more kinds of catalysts having a 10-hour half-life temperature difference of 20 ° C. or more in order to eliminate the remaining acrylonitrile monomer. The catalyst that can be used may be either peroxide type or azobis type, but the 10-hour half-life is preferably 0 ° C to 130 ° C, more preferably 20 ° C to 100 ° C.

  Specifically, diisopropyl peroxycarbonate, dioctyl peroxydicarbonate, t-butyl peroxylaurate, lauroyl peroxide, dioctanoyl peroxide, benzoyl peroxide, azobisisobutyronitrile, azobis (2,4 -Dimethylvaleronitrile), 1,1-azobis (cyclohexane-1-carbonitrile), dimethyl 2,2'-azobis (2-methylpropionate), etc. are used, and azobisisobutyronitrile and 1,1 -The combined use of azobis (cyclohexane-1-carbonitrile) or the combined use of azobis (2,4-dimethylvaleronitrile) and 1,1-azobis (cyclohexane-1-carbonitrile) is more preferable.

  In the present invention, hollow particles are used to improve sensitivity, which is one of the characteristics of the particles, and a hydrophobic emulsion resin, ultraviolet curable resin, water-soluble resin, or the like is used as the binder, and the content is hollow. The binder is preferably 100 parts by weight to 300 parts by weight, and more preferably 100 parts by weight to 200 parts by weight with respect to 100 parts by weight of the particles. Thus, it has been found that the sensitivity can be greatly improved. This is considered to be a result of further improving the smoothness of the surface of the intermediate layer by filling the voids of the hollow particles filled in the heat insulating layer. When the amount of the binder is less than 100 parts by mass, the voids of the hollow particles are Therefore, when the amount exceeds 300 parts by mass, the ratio of the hollow particles in the heat insulating layer is decreased, so that the heat insulating property of the heat insulating layer is decreased and sensitivity may be decreased.

Examples of the hydrophobic resin used in the heat insulating layer include styrene / butadiene copolymer, latex of styrene / butadiene / acrylic ester copolymer, vinyl acetate, vinyl acetate / acrylic acid copolymer, and styrene / acrylic ester copolymer. Examples thereof include emulsions of polymers, acrylic ester resins, polyurethane resins and the like.
In addition, the UV curable resin used for the heat insulation layer includes urethane acrylate water-soluble UV curable resin, epoxy acrylate water-soluble UV curable resin, alkoxy acrylate UV curable resin, polyurethane acrylate UV curable emulsion, acrylic monomer, urethane acrylic. Examples of such oligomers include ether-based urethane acrylate oligomers, ester-based urethane acrylate oligomers, and polyester acrylate oligomers.
Further, the water-soluble resin used in the heat insulating layer includes fully saponified polyvinyl alcohol, carboxyl modified polyvinyl alcohol, partially saponified polyvinyl alcohol, sulfonic acid modified polyvinyl alcohol, silyl modified polyvinyl alcohol, acetoacetyl modified polyvinyl alcohol, diacetone modified polyvinyl. Examples include various modified polyvinyl alcohols such as alcohol.

  In the present invention, known water-soluble polymers can be used in combination as long as the quality such as sensitivity is not impaired. Known binders for water-soluble polymers and aqueous polymer emulsions include starch or derivatives thereof, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose; sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylic Examples thereof include acid ester copolymers, alkali salts of styrene / maleic anhydride, alkali salts of isobutylene / maleic anhydride copolymer, polyacrylamide, sodium alginate, gelatin, casein, and the like. Water-soluble emulsions include styrene / butadiene copolymers, latexes of styrene / butadiene / acrylic ester copolymers, vinyl acetate, vinyl acetate / acrylic acid copolymers, styrene / acrylic ester copolymers, acrylic ester resins, and polyurethane resins. And the like.

In the present invention, an alkaline thickener may be used in the heat insulating layer for improving head matching. An alkaline thickener means a binder that thickens under alkaline conditions. A typical example of such an alkali thickening binder is an emulsion latex containing a styrene-butadiene copolymer as a main component. In the present invention, an alkali-thickening binder can be used alone, but in order to make the binder component stably exist as dispersed particles, for example, a carboxylated latex that is a copolymer of unsaturated carboxylic acid. Etc. are preferably used. That is, when the pH of the carboxylated latex is increased, the highly carboxylated polymer on the particle surface is dissolved in water, so that the viscosity is increased, and thus the viscosity of the binder can be further improved. Since the heat insulation layer has the above-described structure, the dispersion stability of the plastic micro hollow particles is increased, so that it is not necessary to add a normally added thickener such as sodium montmorillonite or modified polyacrylic acid as in the conventional case. . Further, since the alkali thickening binder firmly binds the hollow particles to each other in addition to the thickening action, matching with the thermal head is remarkably improved as compared with the case of using the thickening agent.
The alkali-thickening binder is preferably 1 part by weight to 80 parts by weight and more preferably 5 parts by weight to 50 parts by weight with respect to 100 parts by weight of the hollow particles. The binder is preferably a styrene-butadiene copolymer, but is not limited thereto, and any binder may be used as long as it thickens under alkaline conditions. In addition, a pH adjusting agent is required to keep the heat insulating layer solution under alkali. As such, for example, NH ₃ water is used, but it is limited to this unless it significantly inhibits color development. It is not what is done. In addition to the plastic fine hollow particles and the alkali thickening binder, the heat insulating layer may further contain auxiliary additive components commonly used in this type of reversible thermosensitive recording medium, such as fillers, heat-soluble substances, interfaces, as necessary. An activator or the like can be used. In this case, specific examples of the filler and the heat-soluble material include various materials shown in relation to the thermosensitive recording layer component in the following description.

  In addition to the hollow particles and the binder, if necessary, auxiliary additives such as fillers, heat-fusible components, surfactants and the like that are commonly used in this type of reversible thermosensitive recording medium are used for the heat insulating layer. can do. In order to apply these heat insulating layer components uniformly and at a higher speed, the viscosity of a 20% aqueous dispersion of hollow particles at a liquid temperature of 20 ° C. is preferably 200 mPa · s or less. In the case of a viscosity exceeding 200 mPa · s, the coating liquid produced as described above has a high viscosity and coating unevenness occurs. Further, in order to make the surface of the heat insulating layer formed on the support as described above smoother, the surface may be smoothed by calendering after the heat insulating layer is formed.

<Intermediate layer>
The intermediate layer is used for the purpose of improving adhesion between the heat-sensitive recording layer and the protective layer, preventing alteration of the heat-sensitive recording layer by applying the protective layer, and preventing the additives in the protective layer from being transferred to the heat-sensitive recording layer. It is preferable to provide an intermediate layer between them, which can improve the storage stability of the color image.

When the intermediate layer is a layer in contact with the support-side surface of the protective layer, it preferably contains either an acrylate compound having a pentaerythritol group or an acrylate compound having a dipentaerythritol group, specifically Contains an acrylate compound (C) represented by the following structural formula (5), contains a binder resin and an ultraviolet absorber, and further contains other components as necessary.
However, in said structural formula (5), X represents a pentaerythritol group or a dipentaerythritol group. a represents 1 to 5, and b represents 1 to 5.

  As the binder resin, the resin used in the heat-sensitive recording layer can be used, and among these, by adding a curable resin, the heat resistance of the reversible heat-sensitive recording medium is further improved, and better repeatability is achieved. Durability is obtained.

Examples of the ultraviolet absorber include organic compound-based ultraviolet absorbers such as benzotriazole-based, benzophenone-based, salicylic acid ester-based, cyanoacrylate-based, and cinnamic acid-based, among which benzotriazole-based is preferable. is there.
The content of the ultraviolet absorber is preferably in the range of 0.5 to 80 parts by mass with respect to 100 parts by mass of the resin component of the intermediate layer. The intermediate layer may contain a UV-absorbing or shielding inorganic compound, conventionally known surfactants, leveling agents, antistatic agents and the like as additives.

Moreover, in the said intermediate | middle layer, you may use individually by 1 type from the inorganic filler and / or organic filler which were described by the said protective layer, and may use 2 or more types together. In the case of a plurality, there are no particular limitations on how to combine the inorganic filler and the organic filler. Examples of the shape include a spherical shape, a granular shape, a plate shape, and a needle shape. The content of the filler is preferably 5% by volume to 50% by volume in terms of volume fraction.
The solvent used for the intermediate layer coating solution, the dispersion device of the coating solution, the intermediate layer coating method, the intermediate layer drying method, the curing method, etc. are known methods used in the thermosensitive recording layer and protective layer. Can be used.
There is no restriction | limiting in particular in the thickness of the said intermediate | middle layer, According to the objective, it can select suitably, 0.1 micrometer-20 micrometers are preferable, and 0.5 micrometer-5 micrometers are more preferable.

The reversible thermosensitive recording medium of the present invention is not particularly limited, and can be processed into a shape according to its use. For example, it is processed into a sheet shape, a label shape, a roll shape, or the like.
Sheets that have been processed to a general document size such as A4 size can be printed with a printing / erasing device, so that not only test printing, but also the printing range becomes wider for sheet sizes larger than the card size. It can be widely used for temporary output applications such as process management instructions, circulation documents and meeting materials.
Furthermore, what was processed into roll shape can be used for a display board, a bulletin board, or an electronic blackboard by incorporating in the apparatus which has a printing / erasing part. 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. In this case, the color tone of each thermosensitive recording layer may be the same or different. Also, printing (printable part) such as offset printing or gravure printing on a part or the whole of the same surface as the heat-sensitive recording layer of the reversible thermosensitive recording medium of the present invention or a part of the opposite surface, or an ink jet printer or a thermal transfer printer. A colored layer capable of forming irreversible information such as an arbitrary pattern may be provided by a sublimation printer or the like. Further, an OP varnish layer mainly composed of a curable resin may be provided on a part or the entire surface of the colored layer. 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, the reversible thermosensitive recording medium of the present invention can be provided with a hologram for security. In addition, a design such as a person image, a company emblem, a symbol mark, or the like can be provided by providing irregularities in a relief shape or an intaglio shape for designability.

Formation and deletion of an image on the reversible thermosensitive recording medium can be performed using a known image processing apparatus, and is preferably performed using the image processing apparatus of the present invention described later.
As the image processing apparatus, for example, an apparatus including an image forming unit for forming an image on the reversible thermosensitive recording medium and an image erasing unit for erasing the image is preferably exemplified. Among these, it is preferable to include an image forming and erasing unit that combines the image forming unit and the image erasing unit in that the processing time is short. Specifically, an image processing apparatus or an image forming unit that can process an image by changing energy applied to the thermal head using a thermal head, or an image forming unit is a thermal head, and an image erasing unit is a thermal head or ceramic. Contact pressing type means for adhering heating elements such as heaters (heating elements on which an exothermic resistor is screen-printed on an alumina substrate), hot stamps, heat rollers, heat blocks, etc., or non-contact type means using hot air, infrared rays, etc. An image processing apparatus selected from one of them.

(Reversible thermosensitive recording material)
The reversible thermosensitive recording member of the present invention has an information storage unit and a reversible display unit, the reversible display unit includes the reversible thermosensitive recording medium of the present invention, and other members as necessary. It has.
By providing (integrating) the heat-sensitive recording layer and the information storage unit capable of reversible display on the same card, and displaying a part of the stored information of the information storage unit on the heat-sensitive recording layer, the card holder or the like Even if there is no special device, you can check information just by looking at the card, which is very convenient. Further, when the contents of the information storage unit are rewritten, the reversible thermosensitive recording medium can be repeatedly used by rewriting the display of the reversible thermosensitive recording unit.

The members having the information storage unit and the reversible display unit can be roughly classified into the following two.
(1) A member having an information recording portion is used as a support for a reversible thermosensitive recording medium, and a thermosensitive recording layer is directly formed.
(2) A member having an information recording unit, wherein a support surface of a reversible thermosensitive recording medium formed separately on a support and having a thermosensitive recording layer is adhered.
In these cases (1) and (2), it is necessary to set the functions of the information storage unit and the reversible display unit so that the functions of the information storage unit and the reversible display unit can be exhibited. The thermal recording medium may be provided on the surface of the support opposite to the surface on which the thermosensitive recording layer is provided, or may be provided between the support and the thermosensitive recording layer or on a part of the thermosensitive recording layer.
The information storage unit is not particularly limited, and for example, a magnetic thermosensitive recording layer, a magnetic stripe, an IC memory, an optical memory, an RF-ID tag, a hologram, and the like are preferably used. In particular, in a sheet medium having a size larger than the card size, an IC memory and an RF-ID tag are preferably used. The RF-ID tag includes an IC chip and an antenna connected to the IC chip.

As the magnetic thermosensitive recording layer, commonly used iron oxide, barium ferrite, etc. and vinyl chloride-based, urethane-based resin, nylon-based resin, etc. are used for coating or forming on the support, or vapor deposition, sputtering, etc. It is formed without using resin by a method. The magnetic thermosensitive recording layer may be provided on the surface of the support opposite to the thermosensitive recording layer, or may be provided between the support and the thermosensitive recording layer, on a part of the thermosensitive recording layer. . Further, a reversible thermosensitive material used for display may be used in the storage unit by a barcode, a two-dimensional code, or the like. Among these, magnetic recording and IC are more preferable.
The hologram is preferably rewritable, and examples thereof include a rewritable hologram in which interference light is written on a polymer azobenzene liquid crystal film.

In general, the member having the information recording unit includes a card, a disk, a disk cartridge, or a tape cassette. Specifically, a thick card such as an IC card or an optical card, a flexible disk, a disk cartridge containing a rewritable disk such as a magneto-optical recording disk (MD) or DVD-RAM, or a disk such as a CD-RW. Examples thereof include a disc that does not use a cartridge, a write-once disc such as a CD-R, an optical information recording medium (CD-RW) that uses a phase change storage material, and a video tape cassette.
Further, as a member having both the reversible display unit and the information storage unit, for example, in the case of a card, the card owner can display a part of the information stored in the information storage unit on the thermal recording layer. The information can be confirmed only by looking at the card even without a special device, and the convenience is greatly improved as compared with a card not using the reversible thermosensitive recording medium.

  The information storage unit is not particularly limited as long as it can store necessary information, and can be appropriately selected according to the purpose. For example, magnetic recording, contact IC, non-contact IC, or optical memory is useful. It is.

The magnetic thermosensitive recording layer is formed by coating a support using a metal compound such as iron oxide or barium ferrite, which is usually used, and a resin such as vinyl chloride, urethane or nylon, or a resin. It is formed by a method such as vapor deposition or sputtering using the above metal compound without using it. Further, the thermosensitive recording layer in the reversible thermosensitive recording medium used for display can also be used as a storage unit in a manner such as a barcode or a two-dimensional code.
More specifically, it can be particularly preferably used in the following reversible thermosensitive recording label, reversible thermosensitive recording member, image processing apparatus, image processing method and the like of the present invention. In the present invention, the surface of the reversible thermosensitive recording medium means the surface of the thermosensitive recording layer side and is not limited to the protective layer. It means all or some of the surfaces that come into contact.

The reversible thermosensitive recording member of the present invention has the thermosensitive recording layer capable of reversible display and an information storage unit, and a suitable example of the information storage unit is an RF-ID tag.
FIG. 2 shows a schematic diagram of the RF-ID tag 85. The RF-ID tag 85 includes an IC chip 81 and an antenna 82 connected to the IC chip. The IC chip 81 is divided into four parts: a storage unit, a power supply adjustment unit, a transmission unit, and a reception unit. In the communication, the RF-ID tag 85 and the reader / writer antenna communicate with each other by radio waves to exchange data. Specifically, an RF-ID antenna 82 receives a radio wave from a reader / writer, and an electromotive force is generated by electromagnetic induction or the like by a resonance action. As a result, the IC chip 81 in the RF-ID tag is activated, information in the chip is converted into a signal, and then a signal is transmitted from the RF-ID tag 85. This information is received by the antenna on the reader / writer side and recognized by the data processing device, and data processing is performed on the software side.

  The RF-ID tag 85 is processed into a label shape or a card shape, and the RF-ID tag 85 can be attached to the reversible thermosensitive recording medium 90 of the present invention as shown in FIG. The RF-ID tag 85 can be attached to the heat-sensitive recording layer surface or the back layer surface, but is preferably attached to the back layer surface. In order to bond the RF-ID tag 85 and the reversible thermosensitive recording medium, a known adhesive or pressure-sensitive adhesive can be used.

  4A and 4B show an example in which a reversible thermosensitive recording medium is applied to an industrial rewritable sheet (reversible thermosensitive recording member) 90. FIG. As shown in FIG. 4A, a rewritable display portion 91 is provided on the thermosensitive recording layer side (front surface), and an RF-ID tag is provided on the back surface (back layer) as shown in FIG. 4B. The RF-ID tag 85 may be attached as shown in FIG. 3, but the one having the RF-ID tag 85 is preferable in terms of convenience. In FIG. 4A, 92 indicates barcode printing.

FIG. 5 shows an example of how to use an industrial rewritable sheet in which the reversible thermosensitive recording medium (rewritable sheet) of the present invention is combined with an RF-ID tag. First, information such as an article name and quantity is recorded on a sheet and an RF-ID tag with respect to delivered raw materials, and attached to a returnable box or the like for inspection. In the next process, a processing instruction is given to the delivered raw material, information is recorded in the rewritable sheet and the RF-ID tag, and a processing instruction document is obtained, and the process proceeds to the processing process. Next, the processed product is attached with a rewritable sheet on which ordering information is recorded as an ordering instruction and an RF-ID tag. After the product is shipped, the rewritable sheet is collected, the shipping information is read, and used again as an invoice.

(Reversible thermosensitive recording label)
The reversible thermosensitive recording label of the present invention is a surface opposite to the image forming surface of the reversible thermosensitive recording medium of the present invention (if the thermosensitive recording layer is provided on the support, The surface opposite to the surface on which the heat-sensitive recording layer is formed has at least one of an adhesive layer and a pressure-sensitive adhesive layer, and further includes other layers appropriately selected as necessary. In the case of a reversible thermosensitive recording medium in which a heat-sealable material is used as the support, an adhesive layer or a pressure-sensitive adhesive layer is not necessarily required on the surface opposite to the surface on which the heat-sensitive recording layer is formed. is not.
The shape, structure, size and the like of the adhesive layer to the pressure-sensitive adhesive layer are not particularly limited and can be appropriately selected depending on the purpose. For example, the shape includes a sheet shape, a film shape, and the like. The structure may be a single-layer structure or a laminated structure, and the size may be larger or smaller than the thermosensitive recording layer.

  The material of the adhesive layer to the pressure-sensitive adhesive layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, urea resin, melamine resin, phenol resin, epoxy resin, vinyl acetate resin, acetic acid Vinyl-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 resins, polyvinyl butyral resins, acrylic ester copolymers, methacrylic ester copolymers, natural rubber, cyanoacrylate resins, silicone resins, and the like. These may be used individually by 1 type, may use 2 or more types together, may be a hot melt type, may use a release paper, and may be a non-release paper type.

  The reversible thermosensitive recording label is usually used by being attached to a base sheet such as a card. The reversible thermosensitive recording label to be affixed to the base sheet may be the entire surface of the base sheet, a part thereof, or may be provided on one side or both sides of the base sheet. It is selected appropriately.

  The substrate sheet is not particularly limited in its shape, structure, size and the like, and can be appropriately selected according to the purpose. Examples of the shape include a flat plate shape, and the like. The structure may be a single layer structure or a laminated structure, and the size may be appropriately selected according to the size of the reversible thermosensitive recording medium, for example, chlorine A sheet made of a material such as a containing polymer, a polyester resin, or a biodegradable plastic resin, or a laminate thereof is used.

  The chlorine-containing polymer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, 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, and the like.

  Examples of the polyester resin include polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), or a condensed ester resin of an acid component such as terephthalic acid and isophthalic acid and an alcohol component such as ethylene glycol and cyclohexanedimethanol. (For example, PETG: trademark of Eastman Chemical Co.).

Examples of the biodegradable plastic resin include polylactic acid resins, natural polymer resins composed of starch and modified polyvinyl alcohol, and microorganism-produced resins composed of β-hydroxybutyric acid and β-hydroxyvaleric acid. Can be mentioned.
Furthermore, synthetic resin sheets or synthetic papers such as polyacetate resin, polystyrene (PS) resin, epoxy resin, polyvinyl chloride (PVC) resin, polycarbonate (PC) resin, polyamide resin, acrylic resin, silicone resin, etc. These materials may be appropriately combined, or a laminate of these materials may be used.

  As the laminate, 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 laminated on the front and back surfaces of the core sheet as an oversheet, Moreover, for example, a core sheet in which two white PETG sheets having a thickness of 250 μm are laminated, and a transparent PETG having a thickness of 100 μm laminated as an oversheet on the front and back surfaces of the core sheet, and the like can be mentioned.

As a method of attaching the base sheet and the reversible thermosensitive recording label, for example, as shown in FIG. 6, two sheets in which the reversible thermosensitive recording label 3 and the base sheet 4 are overlapped so as to face each other. After being sandwiched by the mirror plate 2, pressing is performed while applying heat with the hot plate 1.
Further, as shown in FIG. 7, it can be performed in the same manner as in FIG. 6 except that the base sheet 4 formed by superposing the core sheet 6 and the oversheet 7 is used.

Thermocompression bonding, known means, for example hot plate 1 by using a hot press provided, ^{usually, 5kgf / cm 2 ~70kgf / cm} 2, preferably to a pressure of ^{10kgf / cm 2 ~50kgf / cm 2} , It is carried out in the range of 80 ° C to 170 ° C, preferably 90 ° C to 150 ° C.
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 About 130 to 150 ° C is preferable. Further, the heating temperature when a laminate such as transparent PETG / white PETG / white PETG / transparent PETG is used is preferably about 100 ° C. to 130 ° C.

Further, as another method of attaching the reversible thermosensitive recording label and the base sheet, heat bonding can be performed after heat bonding in advance. The heat bonding is performed by pressing a rubber roll or the like, and then heat bonding is completed to complete the heat bonding.
The conditions for the thermal bonding are not particularly limited, and the optimum conditions are determined depending on the substrate sheet to be used. Usually, the thermal bonding is performed at a temperature of 90 ° C. to 130 ° C. for 1 hour or less and for 1 to 50 minutes. it can.

  In the present invention, for example, when a reversible thermorecording label having a protective layer whose surface is roughened by a filler or the like is thermocompression bonded onto a base sheet such as a card, the filler on the surface of the protective layer is contained in the protective layer by thermocompression. Or the surface gloss increases by being pushed into the lower layer, the effect of the filler disappears, and the durability decreases repeatedly, or if the recording and erasure are repeated with the surface gloss increased, the gloss of the recorded and erased portion However, by providing the protective layer of the reversible thermosensitive recording medium of the present invention, such a problem can be solved. it can. In this case, it is preferable that the reversible thermosensitive recording medium has a surface roughness of 0.15 [mu] m or less because glossiness can be further obtained.

  When the reversible thermosensitive recording label has at least one of the adhesive layer and the pressure-sensitive adhesive layer, the entire surface of a thick substrate such as a card made of vinyl chloride with a magnetic stripe, which is difficult to apply the thermosensitive recording layer, or A part of the information can be pasted, and a part of the information stored in the magnetism can be displayed.

  The reversible thermosensitive recording label includes a thick card such as an IC card or an optical card, a flexible disk, a disk cartridge containing a rewritable disk such as a magneto-optical recording disk (MD) or DVD-RAM, a CD-RW. Such as discs that do not use disc cartridges, write-once discs such as CD-R, optical information recording media (CD-RW) using phase change storage materials, and display labels on video tape cassettes. it can.

  FIG. 8 shows an example in which the reversible thermosensitive recording label 10 of the present invention is affixed onto an MD disk cartridge 70. In this case, it is possible to apply to uses such as automatically changing the display contents in accordance with the change of the contents stored in the MD. In the case of a disc that does not use a disc cartridge such as a CD-RW, the reversible thermosensitive recording label of the present invention may be directly attached to the disc.

  FIG. 9 shows an example in which the reversible thermosensitive recording label 10 of the present invention is affixed on the CD-RW 71. In this case, the reversible thermosensitive recording label 10 may be pasted on a write-once disc such as a CD-R instead of the CD-RW 71, and a part of the stored information added to the CD-R may be rewritten and displayed. Is possible.

  FIG. 10 shows an example in which the reversible thermosensitive recording label 10 of the present invention is pasted on an optical information recording medium (CD-RW) using an AgInSbTe phase change type storage material. The basic configuration of this CD-RW is that a first dielectric layer 110, an optical information storage layer 109, a second dielectric layer 108, a reflective heat dissipation layer 107, and an intermediate layer 106 are formed on a base 111 having a guide groove. The hard coat layer 112 is provided on the back surface of the substrate 111 in order. The reversible thermosensitive recording label 10 of the present invention is affixed on the CD-RW intermediate layer 106. The reversible thermosensitive recording label 10 includes an adhesive layer and an adhesive layer 105, a back layer 104, a support 103, a thermosensitive recording layer 102, and a protective layer 101 in this order. The dielectric layer is not necessarily provided on both sides of the optical information storage layer, but the first dielectric layer 110 may be provided when the substrate is made of a material having low heat resistance such as polycarbonate resin. preferable.

FIG. 11 shows an example in which the reversible thermosensitive recording label 10 of the present invention is stuck on a video cassette 72. In this case, the display contents can be automatically changed in accordance with changes in the contents stored in the video tape cassette 72.
As a method of providing the reversible thermosensitive recording function on any of a card, a disk, a disk cartridge, and a tape cassette, in addition to the method of attaching the reversible thermosensitive recording label, the thermosensitive recording layer is formed on them. Examples include a direct coating method, a method in which the heat-sensitive recording layer is formed on another support in advance, and the heat-sensitive recording layer is transferred onto the card, the disk, the disk cartridge, and the tape cassette. . In the case of the method for transferring the thermosensitive recording layer, the adhesive layer such as a hot melt type or the adhesive layer may be provided on the thermosensitive recording layer. When the reversible thermosensitive recording label is affixed on a rigid object such as the card, the disc, the disc cartridge, and the tape cassette, or when the thermosensitive recording layer is provided, the contact with the thermal head is improved. In order to form an image uniformly, it is preferable to provide a layer serving as a cushion or a sheet between a rigid substrate and a label or the heat-sensitive recording layer.

  In the reversible thermosensitive recording medium of the present invention, for example, as shown in FIG. 12, a reversible thermosensitive recording layer 13, an intermediate layer 14, and a protective layer 15 are provided on a support 11. As shown in FIG. 13, a reversible thermosensitive recording layer 13 and a protective layer 15 are provided on a support 11, and a back layer 16 is provided on the back surface of the support 11. An embodiment such as a film can be employed.

  The film (reversible thermosensitive recording medium) of each of these aspects can be suitably used for various sheet-like industrial rewritable sheets provided with the RF-ID tag 85 shown in FIG. For example, as shown to FIG. 14A, it can use as a form processed into the reversible thermosensitive recording card 21 which has the print display part 23. FIG. As shown in FIG. 14B, a magnetic recording part is formed on the back side of the card, and a back layer 24 is formed on the magnetic recording part.

  In addition, the reversible thermosensitive recording member (card) shown in FIG. 15A is formed on a support by forming a film provided with a reversible thermosensitive recording layer and a protective layer into a card shape, thereby forming a recess 25 for accommodating an IC chip. And processed into a card shape. In FIG. 15A, the rewrite recording portion 26 is labeled on a card-like reversible thermosensitive recording medium, and an IC chip embedding recess 25 is formed at a predetermined location on the back side of the card. As shown in FIG. 15B, the wafer 231 is assembled and fixed in the recess 25. In the wafer 231, an integrated circuit 233 is provided on a wafer substrate 232, and a plurality of contact terminals 234 that are electrically connected to the integrated circuit 233 are provided on the wafer substrate 232. The contact terminal 234 is exposed on the back side of the wafer substrate 232 and is configured such that a dedicated printer (reader / writer) can electrically contact the contact terminal 234 to read or rewrite predetermined information. Yes.

Next, the function of the reversible thermosensitive recording card will be described with reference to FIG.
FIG. 16A is a schematic configuration block diagram showing the integrated circuit 233. FIG. 16B is a configuration block diagram showing an example of data stored in the RAM. The integrated circuit 233 is composed of, for example, an LSI, in which a CPU 235 capable of executing a control operation in a predetermined procedure, a ROM 236 for storing operation program data of the CPU 235, writing of necessary data, and the like. A RAM 237 capable of reading is included. Further, the integrated circuit 233 receives an input signal, gives input data to the CPU 235, receives an output signal from the CPU 235, and outputs it to the outside. Although not shown, a power-on reset circuit, A clock generation circuit, a pulse frequency division circuit (interrupt pulse generation circuit), and an address decoding circuit.
The CPU 235 can execute the operation of the interrupt control routine in accordance with the interrupt pulse periodically given from the pulse frequency dividing circuit. The address decoding circuit decodes address data from the CPU 235 and provides signals to the ROM 236, the RAM 237, and the input / output interface 238, respectively. A plurality (eight in FIG. 16A) of contact terminals 234 are connected to the input / output interface 238, and predetermined data from the dedicated printer (reader / writer) is transmitted from the contact terminals 234 via the input / output interface 238. Input to the CPU 235. The CPU 235 performs each operation in response to the input signal and according to the program data stored in the ROM 236, and outputs predetermined data and signals to the sheet reader / writer via the input / output interface 238.

  As illustrated in FIG. 16B, the RAM 237 includes a plurality of storage areas 239a to 239g. For example, the sheet number is stored in the storage area 239a. For example, the storage area 239b stores ID data such as the name, affiliation, and telephone number of the sheet manager. For example, the storage area 239c stores information on the remaining margin or handling that can be used by the user. For example, the storage area 239d, the storage area 239e, the storage area 239f, and the storage area 239g store information related to the previous manager, the previous user, and the like.

  There is no particular limitation on at least one of the reversible thermosensitive recording label and the reversible thermosensitive recording member of the present invention, and image processing can be performed by various image processing methods and image processing apparatuses. An image can be formed and erased suitably using an image processing apparatus.

(Image processing method and image processing apparatus)
The image processing apparatus of the present invention includes at least one of an image forming unit and an image erasing unit, and further includes other units selected as necessary, for example, a transport unit, a control unit, and the like.
In the image processing method of the present invention, the reversible thermosensitive recording medium of the present invention is heated to perform at least one of formation and erasure of an image, and other processes appropriately selected as necessary, for example, a transport process And a control process.
The image processing method of the present invention can be preferably carried out by the image processing apparatus of the present invention, and at least one of image formation and image erasure by heating the reversible thermosensitive recording medium of the present invention is the image. It can be performed by at least one of a forming unit and an image erasing unit, and the other steps can be performed by the other units.

-Image forming means and image erasing means-
The image forming means is a means for forming an image by heating the reversible thermosensitive recording medium of the present invention. The image erasing means is means for erasing an image by heating the reversible thermosensitive recording medium of the present invention.
There is no restriction | limiting in particular as said image formation means, According to the objective, it can select suitably, For example, a thermal head, a laser, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.
The image erasing means is means for erasing an image by heating the reversible thermosensitive recording medium of the present invention. For example, a hot stamp, a ceramic heater, a heat roller, a heat block, hot air, a thermal head, a laser, etc. Irradiation apparatus etc. are mentioned. Among these, a ceramic heater is preferable. By using the ceramic heater, the apparatus can be miniaturized, a stable erased state can be obtained, and an image with good contrast can be obtained. There is no restriction | limiting in particular as set temperature of the said ceramic heater, According to the objective, it can select suitably, For example, 110 degreeC or more is preferable, 112 degreeC or more is more preferable, 115 degreeC or more is still more preferable.
By using the thermal head, the size can be further reduced, the power consumption can be reduced, and a battery-driven handy type device can also be realized. Also, a single thermal head can be used for recording and erasing the image. In this case, the size can be further reduced. When recording and erasing with one thermal head, once all the previous images are erased, a new image may be recorded again, or the energy is changed for each image and the previous image is erased at one time. An overwrite method for recording images is also possible. In the overwrite method, the time required for recording and erasing the image is reduced, leading to an increase in recording speed.
When a reversible thermosensitive recording member (card) having the thermosensitive recording layer and the information storage unit is used, the apparatus includes means for reading the memory of the information storage unit, rewriting means, and the like.
The transport means is not particularly limited as long as it has a function of sequentially transporting the reversible thermosensitive recording medium, and can be appropriately selected depending on the purpose. For example, the transport belt, the transport roller, the transport belt and the transport belt The combination with a roller etc. are mentioned.
The control means is not particularly limited as long as it has a function of controlling each step, and can control each step, and examples thereof include devices such as a sequencer and a computer.

One mode for carrying out the image processing method of the present invention by the image processing apparatus of the present invention will be described with reference to FIGS.
As shown in FIG. 17, the image processing apparatus 100 includes a heat roller 96, a thermal head 95, and a conveyance roller. In this image processing apparatus, the image recorded on the heat-sensitive recording layer is erased by heating with the heat roller 96. Next, the processed new information is recorded on the thermal recording layer by the thermal head 95. In FIG. 17, 97 represents a paper feed tray, and 98 represents a rewritable sheet (reversible thermosensitive recording medium).

When the reversible thermosensitive recording medium has an RF-ID tag, an RF-ID reader 99 is further provided as shown in FIGS. In this case, there is also an aspect of a parallel type image processing apparatus as shown in FIG.
As shown in FIGS. 18 and 19, in this image processing apparatus 100, first, information of the RF-ID tag attached to the reversible thermosensitive recording medium is read by the RF-ID reader / writer 99, and new information is read by RF. -After inputting the ID, the image recorded on the heat-sensitive recording layer is erased by heating with a heat roller. Further, based on the information read and rewritten by the RF-ID reader / writer, the processed new information is recorded on the thermal recording layer by the thermal head. Other than the RF-ID reader / writer, a bar code reader, a magnetic head, or the like may be used. In the case of a barcode reader, after reading the barcode information already recorded on the reversible thermosensitive recording layer, the barcode and visualization information recorded on the reversible thermosensitive recording layer are erased by the heat roller, and the barcode is read from the barcode. New information processed based on the recorded information is recorded on the reversible thermosensitive recording layer by the thermal head as barcode and visualization information.

The image processing apparatus shown in FIG. 17 or 18 has a tray on which a reversible thermosensitive recording medium is stacked, and the medium is picked up one by one by a paper feeding method such as a friction pad method. The transported medium is transported by transport rollers and sent to the RF-ID reader / writer, where data is read and written. Further, the reversible thermosensitive recording medium is conveyed by the conveying roller to the heat roller section which is an erasing unit, and the visualization information recorded on the medium is erased. Then, it is conveyed to a thermal head unit and new information is recorded on a reversible thermosensitive recording medium. Thereafter, the reversible thermosensitive recording medium is conveyed by the conveying roller, and the medium is unloaded from the upper paper discharge unit.
Here, the set temperature of the heat roller is preferably set to match the erasing temperature of the reversible thermosensitive recording medium. For example, the heat roller surface temperature is preferably 100 ° C. or higher and 190 ° C. or lower, more preferably 110 ° C. or higher and 180 ° C. or lower, and even more preferably 115 ° C. or higher and 170 ° C. or lower.

Further description will be made with reference to FIGS. 20A and 20B. The image processing apparatus shown in FIG. 20A includes a thermal head 53 serving as the heat processing means, a ceramic heater 38, a magnetic head 34, and conveying rollers 31, 40, and 47.
As shown in FIG. 20A, in this image processing apparatus, first, information stored in a magnetic thermosensitive recording layer of a reversible thermosensitive recording medium is read by a magnetic head. Next, the image recorded on the reversible thermosensitive recording layer is erased by heating with a ceramic heater. Furthermore, new processed information is recorded on the reversible thermosensitive recording layer by the thermal head based on the information read by the magnetic head. Thereafter, the information in the magnetic thermosensitive recording layer is also rewritten with new information.

  In the image processing apparatus shown in FIG. 20A, the reversible thermosensitive recording medium 5 provided with the magnetic thermosensitive recording layer on the opposite side of the thermosensitive recording layer is conveyed along the conveying path indicated by the reciprocating arrow, or the conveying path. Are conveyed in the reverse direction in the apparatus. The reversible thermosensitive recording medium 5 is magnetically recorded or erased on the magnetic thermosensitive recording layer between the magnetic head 34 and the transport roller 31, and is heat-treated for image erasure between the ceramic heater 38 and the transport roller 40. An image is formed between the conveyance rollers 47. Then, it is carried out of the apparatus. As described above, the set temperature of the ceramic heater 38 is preferably 110 ° C. or higher, more preferably 112 ° C. or higher, and particularly preferably 115 ° C. or higher. However, the rewriting of the magnetic recording may be performed before or after the image erasure by the ceramic heater. If desired, after passing between the ceramic heater 38 and the transport roller 40 or after passing between the thermal head 53 and the transport roller 47, the transport path is transported in the reverse direction. A second heat treatment by the ceramic heater 38 and a second printing process by the thermal head 53 can be performed.

  In the image processing apparatus of FIG. 20B, the reversible thermosensitive recording medium 5 inserted from the entrance / exit 30 advances along the conveyance path 50 shown by a one-dot broken line, or reverses the inside of the apparatus along the conveyance path 50. Proceed in the direction. The reversible thermosensitive recording medium 5 inserted from the entrance / exit 30 is transported in the recording apparatus by a transport roller 31 and a guide roller 32. When the sensor 33 reaches a predetermined position in the transport path 50, its presence is recognized by the control means 34c via the control means 34c, and magnetic recording or recording is erased on the magnetic thermosensitive recording layer between the magnetic head 34 and the platen roller 35. Between the ceramic heater 38 and the platen roller 44, which pass between the guide roller 39 and the transport roller 40, recognize the presence of the sensor 43 via the ceramic heater control means 38 c, and operate. Heat treatment is performed for erasing the image, and the image is conveyed through the conveyance path 50 by the conveyance rollers 45, 46 and 47, and operates by recognizing its presence via the thermal head control means 53c by the sensor 51 at a predetermined position. An image is formed between the thermal head 53 and the platen roller 52. It is unloaded outside the apparatus through the outlet 61 by the guide roller 60. Here, there is no restriction | limiting in particular as preset temperature of the ceramic heater 38, According to the objective, it can select suitably, As mentioned above, 110 degreeC or more is preferable, 112 degreeC or more is more preferable, 115 degreeC or more is preferable. Particularly preferred.

  If desired, reversible thermosensitive recording is performed by a conveyor belt 58 which is guided to the conveyor path 56b by switching the conveyor path switching means 55a and moves in the reverse direction by the operation of a limit switch 57a input by pressing the reversible thermosensitive recording medium 5. After the medium 5 is again heat-treated between the thermal head 53 and the platen roller 52, the medium 5 is conveyed in the forward direction via the conveying path 49b, the limit switch 57b, and the conveying belt 48 which are communicated by switching the conveying path switching means 55b. From 56a, it can be carried out of the apparatus through the outlet 61 by the conveying roller 59 and the guide roller 60. Further, such branched conveyance paths and conveyance switching means can be provided on both sides of the ceramic heater 38. In that case, the sensor 43 a is preferably provided between the platen roller 44 and the transport roller 45.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
<Preparation of reversible thermosensitive recording medium>
-Preparation of thermosensitive recording layer-
The following composition was pulverized and dispersed using a ball mill so that the average particle size was 0.1 μm to 1.0 μm.
2-anilino-3-methyl-6dibutylaminofluorane (solid content: 100% by mass): 1 part by mass Electron accepting compound represented by the following structural formula (developer, solid content: 100% by mass) ... 4 parts by mass
Dialkylurea (Nippon Kasei Co., Ltd., Hallene SB, solid content: 100% by mass): 1 part by mass Acrylic polyol resin 40% by mass solution (manufactured by Mitsubishi Rayon Co., Ltd., LR327): 10 parts by mass ... 80 parts by mass 4 parts by mass of isocyanate (manufactured by Nippon Polyurethane Co., Ltd., Coronate HL, solid content: 75% by mass) was added to the obtained dispersion and stirred well to prepare a thermal recording layer coating solution. Next, the obtained heat-sensitive recording layer coating solution was applied onto a 188 μm thick cloudy polyester film (Tetron film, manufactured by Teijin DuPont) using a wire bar, dried at 100 ° C. for 2 minutes, and then 60 ° C. For 24 hours to provide a thermosensitive recording layer having a thickness of 12 μm to 13 μm.

-Production of protective layer-
The following composition was pulverized and dispersed using a ball mill so that the average particle size was 2 μm to 3 μm to prepare a protective layer coating solution.
Compound represented by the above structural formula (1) Dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA, solid content: 100% by mass): 4 parts by mass: represented by the above structural formula (2) Compound dipentaerythritol acrylate (Nippon Kayaku Co., Ltd., KAYARAD DPCA-60) ... 21 parts by mass Compound of structural formula (1) / compound of structural formula (2) = 1.6 / 8.4 ( (Mass ratio)
-Silica (Mizusawa Chemical Co., Ltd., P-526) ... 2 parts by mass-Photopolymerization initiator (Ciba Geigy Japan, Irgacure 184) ... 1 part by mass-Isopropyl alcohol ... 60 parts by mass -Toluene: 10 parts by mass The obtained protective layer coating solution was applied onto the heat-sensitive recording layer with a wire bar, dried by heating at 90 ° C for 1 minute, and then under an ultraviolet lamp with an irradiation energy of 80 W / cm. Crosslinking was performed to provide a protective layer having a thickness of 3 μm. Thus, a reversible thermosensitive recording medium of Example 1 was produced.

(Example 2)
<Preparation of reversible thermosensitive recording medium>
-Preparation of thermosensitive recording layer-
The following composition was pulverized and dispersed using a ball mill so that the average particle size was 0.1 to 1.0 μm.
2-anilino-3-methyl-6dibutylaminofluorane: 1 part by mass Electron accepting compound (developer) represented by the following structural formula: 4 parts by mass
・ Dialkylurea (Nippon Kasei Co., Ltd., Haclean SB) ・ ・ ・ 1 mass part ・ Acrylic polyol resin 40 mass% solution (Mitsubishi Rayon Co., Ltd., LR327) ・ ・ ・ 10 mass parts ・ Methyl ethyl ketone ... 80 mass parts To the obtained dispersion, 4 parts by mass of isocyanate (manufactured by Nippon Polyurethane Co., Ltd., Coronate HL) was added and stirred well to prepare a thermal recording layer coating solution. Next, the obtained heat-sensitive recording layer coating solution was applied onto a 125 μm thick white turbid polyester film (Tetron DuPont, Tetron film U2L98W) using a wire bar and dried at 100 ° C. for 2 minutes. Heating was performed at 60 ° C. for 24 hours to provide a thermosensitive recording layer having a thickness of 12 μm to 13 μm.

-Production of protective layer-
The following composition was pulverized and dispersed using a ball mill so that the average particle size was 2 μm to 3 μm to prepare a protective layer coating solution.
-Compound represented by the above structural formula (1) Dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA)-7 parts by mass-Compound represented by the above structural formula (2) Dipentaerythritol Acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPEA-12) ... 18 parts by mass Compound of structural formula (1) / compound of structural formula (2) = 2.8 / 7.2 (mass ratio)
Silica (Mizusawa Chemical Co., Ltd., P-527) 3 parts by mass Photopolymerization initiator (Ciba Geigy Japan, Irgacure 184) 1 part by mass Isopropyl alcohol 60 parts by mass -Toluene: 10 parts by mass The obtained protective layer coating solution was applied onto the heat-sensitive recording layer with a wire bar, dried by heating at 90 ° C for 1 minute, and then under an ultraviolet lamp with an irradiation energy of 80 W / cm. Crosslinking was performed to provide a protective layer having a thickness of 3 μm. Thus, the reversible thermosensitive recording medium of Example 2 was produced.

(Example 3)
<Preparation of reversible thermosensitive recording medium>
-Preparation of thermosensitive recording layer-
The following composition was pulverized and dispersed using a ball mill so that the average particle size was 0.1 μm to 1.0 μm.
2-anilino-3-methyl-6dibutylaminofluorane: 1 part by mass Electron accepting compound (developer) represented by the following structural formula: 4 parts by mass
・ Dialkylurea (Nippon Kasei Co., Ltd., Haclean SB): 1 part by mass ・ Acrylic polyol resin 40% by mass solution (Mitsubishi Rayon Co., Ltd., LR340): 10 parts by mass ・ Methyl ethyl ketone: 80 parts by mass 4 parts by mass of isocyanate (manufactured by Nippon Polyurethane Co., Ltd., Coronate HL) was added to the obtained dispersion and stirred well to prepare a thermal recording layer coating solution. Next, the obtained heat-sensitive recording layer coating solution was applied onto a 100 μm-thick white turbid polyester film (Tetron film, manufactured by Toray Industries, Inc.) using a wire bar, dried at 100 ° C. for 2 minutes, and then 60 ° C. For 24 hours to provide a thermosensitive recording layer having a thickness of 12 μm to 13 μm.

-Production of protective layer-
The following composition was pulverized and dispersed using a ball mill so that the average particle diameter was 2 to 3 μm to prepare a protective layer coating solution.
-Compound represented by the above structural formula (1) Dipentaerythritol acrylate (Nippon Kayaku Co., Ltd., KAYARAD DPHA) ... 9 parts by mass-Compound represented by the above structural formula (2) Pentaerythritol acrylate (Nippon Kayaku Co., Ltd., KAYARAD THE-330) ... 16 mass parts Compound of structural formula (1) / compound of structural formula (2) = 3.6 / 6.4 (mass ratio)
-Talc (Fuji Talc Kogyo Co., Ltd., LMS-300)-3 parts by mass-Photopolymerization initiator (Nippon Ciba Geigy Co., Ltd., Irgacure 184)-1 part by mass-Isopropyl alcohol-60 parts by mass -Toluene: 10 parts by mass The obtained protective layer coating solution was coated on the heat-sensitive recording layer with a wire bar, dried by heating at 90 ° C for 1 minute, and then under an ultraviolet lamp with an irradiation energy of 80 W / cm. Crosslinking was performed to provide a protective layer having a thickness of 3 μm. Thus, the reversible thermosensitive recording medium of Example 3 was produced.

Example 4
<Preparation of reversible thermosensitive recording medium>
-Preparation of thermosensitive recording layer-
The following composition was pulverized and dispersed using a ball mill so that the average particle size was 0.1 to 1.0 μm.
2-anilino-3-methyl-6dibutylaminofluorane: 1 part by mass Electron accepting compound (developer) represented by the following structural formula: 4 parts by mass
・ Dialkylurea (Nippon Kasei Co., Ltd., Haclean SB): 1 part by mass ・ Acrylic polyol resin 40% by mass solution (Mitsubishi Rayon Co., Ltd., LR340): 10 parts by mass ・ Methyl ethyl ketone: 80 parts by mass 4 parts by mass of isocyanate (manufactured by Nippon Polyurethane Co., Ltd., Coronate HL) was added to the obtained dispersion and stirred well to prepare a thermal recording layer coating solution. Next, the obtained heat-sensitive recording layer coating solution was coated on a 75 μm thick white turbid polyester film (Tetron Film U3L99W, manufactured by Teijin DuPont Co., Ltd.) using a wire bar and dried at 100 ° C. for 2 minutes. Heating was performed at 60 ° C. for 24 hours to provide a heat-sensitive recording layer having a thickness of 12 to 13 μm.

-Production of protective layer-
The following composition was pulverized and dispersed using a ball mill so that the average particle diameter was 2 to 3 μm to prepare a protective layer coating solution.
-Compound represented by the above structural formula (1) Dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA) ... 12 parts by mass-Compound represented by the above structural formula (2) Pentaerythritol acrylate (Nippon Kayaku Co., Ltd., KAYARAD TPA-330) ... 13 mass parts Compound of structural formula (1) / compound of structural formula (2) = 4.8 / 5.2 (mass ratio)
-Talc (Fuji Talc Kogyo Co., Ltd., LMS-300)-3 parts by mass-Photopolymerization initiator (Nippon Ciba Geigy Co., Ltd., Irgacure 184)-1 part by mass-Isopropyl alcohol-60 parts by mass -Toluene: 10 parts by mass The obtained protective layer coating solution was coated on the heat-sensitive recording layer with a wire bar, dried by heating at 90 ° C for 1 minute, and then under an ultraviolet lamp with an irradiation energy of 80 W / cm. Crosslinking was performed to provide a protective layer having a thickness of 3 μm. Thus, a reversible thermosensitive recording medium of Example 4 was produced.

(Example 5)
<Preparation of reversible thermosensitive recording medium>
-Preparation of thermosensitive recording layer-
Except that dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA, solid content 100 mass%) was added to the dispersion obtained in Example 1 so that the mass ratio was 0.01. A thermosensitive recording layer was provided in the same manner as in Example 1.
-Production of protective layer-
In Example 1, instead of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA), which is a compound represented by the above structural formula (1), a compound represented by the above structural formula (1) A reversible thermosensitive recording medium of Example 5 was produced in the same manner as in Example 1 except that dipentaerythritol acrylate (Nippon Kayaku Co., Ltd., KAYARAD D-310) was used.

(Example 6)
<Preparation of reversible thermosensitive recording medium>
-Preparation of thermosensitive recording layer-
A thermosensitive recording layer was provided in the same manner as in Example 2.

-Production of intermediate layer-
An intermediate layer coating solution prepared by mixing and stirring the following composition on the heat-sensitive recording layer was applied with a wire bar and dried by heating at 100 ° C. to provide an intermediate layer having a thickness of 1.5 μm.
・ Zinc oxide (Sumitomo Osaka Cement Co., Ltd., ZS303, solid content: 32% by mass) ... 4 parts by mass Thermosetting resin (Mitsubishi Rayon Co., Ltd., LR503, solid content: 50% by mass) ... 2 masses Part Coronate HL (manufactured by Nippon Polyurethane Co., Ltd., solid content 75 mass%) 0.5 mass part Methyl ethyl ketone 4 mass parts Dipentaerythritol acrylate (so that the mass ratio is 0.02) Nippon Kayaku Co., Ltd., KAYARAD DPHA, solid content 100 mass%) was added.
・ Dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA) ... 0.02 parts by mass

-Production of protective layer-
In Example 2, instead of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA), which is a compound represented by the above structural formula (1), a compound represented by the above structural formula (1) A protective layer was provided in the same manner as in Example 2 except that dipentaerythritol acrylate (Nippon Kayaku Co., Ltd., KAYARAD D-310) was used.

-Production of back layer-
The following composition was mixed and a back layer coating solution was prepared by a conventional method.
Pentaerythritol hexaacrylate (Nippon Kayaku Co., Ltd., KAYARAD DPHA) 3 parts by mass Ultraviolet curable antistatic agent (Shin-Nakamura Chemical Co., Ltd. U-201PA-60) 7 parts by mass Photopolymerization initiator (Nippon Ciba-Geigy Co., Ltd., Irgacure 184) ... 0.5 parts by mass Silica (Mizusawa Chemical Co., Ltd., P-526) ... 1 part by massIsopropyl alcohol ... 17. 5 parts by mass Next, the coating solution for the back layer was applied with a wire bar on the surface of the support on which the heat-sensitive recording layer, the intermediate layer, and the protective layer had already been applied, and was applied at 100 ° C. After drying for 2 minutes, curing was performed at 60 ° C. for 24 hours to form a back layer having a thickness of 4 μm, and a reversible thermosensitive recording medium was produced.

(Example 7)
<Preparation of reversible thermosensitive recording medium>
-Preparation of thermosensitive recording layer-
A thermosensitive recording layer was provided in the same manner as Example 3.
-Production of intermediate layer-
An intermediate layer was provided in the same manner as in Example 6.
-Production of protective layer-
In Example 3, instead of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA), which is a compound represented by the above structural formula (1), a compound represented by the above structural formula (1) A protective layer was provided in the same manner as in Example 3 except that dipentaerythritol acrylate (Nippon Kayaku Co., Ltd., KAYARAD D-310) was used.
-Production of back layer-
A back layer was provided in the same manner as in Example 6 to produce a reversible thermosensitive recording medium.

(Example 8)
<Preparation of reversible thermosensitive recording medium>
-Preparation of thermosensitive recording layer-
A thermosensitive recording layer was provided in the same manner as in Example 4.
-Production of intermediate layer-
An intermediate layer was provided in the same manner as in Example 6.
-Production of protective layer-
In Example 4, instead of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA), which is a compound represented by the above structural formula (1), a compound represented by the above structural formula (1) A protective layer was provided in the same manner as in Example 4 except that dipentaerythritol acrylate (Nippon Kayaku Co., Ltd., KAYARAD D-310) was used.
-Production of back layer-
A back layer was provided in the same manner as in Example 6 to produce a reversible thermosensitive recording medium.

Example 9
<Preparation of reversible thermosensitive recording medium>
-Production of heat insulation layer-
The following composition was pulverized and dispersed until the hollow particles were sufficiently loosened to prepare a heat insulating layer coating solution. Next, the obtained heat insulating layer coating solution was applied on a white turbid polyester film (manufactured by Teijin DuPont Co., Ltd., Tetoron film) with a thickness of 188 μm, dried at 110 ° C. for 4 minutes, and thickness 22 μm. A thermal insulation layer of ˜24 μm was provided.
-Hollow particle aqueous dispersion (solid content concentration 30% by mass) ... 30 parts by mass Hollow particles: glass transition temperature (Tg) 105 ° C, hollow rate 89%, D100 = 10 µm, D100 / D50 = 2.2
・ Polyurethane resin emulsion: 28 parts by mass (solid content concentration: 35% by mass, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Superflex 150)
-Completely saponified polyvinyl alcohol aqueous solution (solid content concentration 16% by mass) ... 9 parts by mass-Water ... 50 parts by mass

-Preparation of thermosensitive recording layer-
A thermosensitive recording layer was provided in the same manner as in Example 5.
-Production of intermediate layer-
In Example 6, 0.02 mass% addition of dipentaerythritol acrylate (Nippon Kayaku Co., Ltd., KAYARAD DPHA) in the intermediate layer was added so that the mass ratio was 0.05. An intermediate layer was provided in the same manner as in Example 6 except that 0.05% by mass (KAYARAD PET-30, solid content 100% by mass) was added.
-Production of protective layer-
In Example 5, instead of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD D-310) which is a compound of structural formula (1) of the protective layer composition, the compound of structural formula (1) is used. A protective layer was provided in the same manner as in Example 5 except that dipentaerythritol acrylate (manufactured by Negami Kogyo Co., Ltd., UN-3320HA) was used.
-Production of back layer-
A back layer was provided in the same manner as in Example 6 to produce a reversible thermosensitive recording medium.

(Example 10)
<Preparation of reversible thermosensitive recording medium>
-Production of heat insulation layer-
Example 9 was the same as Example 9 except that a 125 μm thick white turbid polyester film (Teijin DuPont, Tetron film U2L98W) was used instead of a 188 μm thick white turbid polyester film (Tetron film, Tetron film). Thus, a heat insulating layer was provided.
-Preparation of thermosensitive recording layer-
A thermosensitive recording layer was provided in the same manner as in Example 6.
-Production of intermediate layer-
In Example 6, instead of 0.02% by mass of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA), pentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD PET-30) 0 An intermediate layer was provided in the same manner as in Example 6 except that 0.06% by mass was added.
-Production of protective layer-
In Example 6, instead of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD D-310) as a protective layer composition, dipentaerythritol acrylate (manufactured by Negami Industrial Co., Ltd., UN-3320HA) was used. A protective layer was provided in the same manner as in Example 6 except that it was used.
-Production of back layer-
A back layer was provided in the same manner as in Example 6 to produce a reversible thermosensitive recording medium.

(Example 11)
<Preparation of reversible thermosensitive recording medium>
-Production of heat insulation layer-
In Example 9, except that a white turbid polyester film (manufactured by Toray Industries, Inc.) having a thickness of 100 μm was used instead of a white turbid polyester film (produced by Teijin DuPont Co., Ltd., Tetoron film) having a thickness of 188 μm, A heat insulating layer was provided.
-Preparation of thermosensitive recording layer-
A thermosensitive recording layer was provided in the same manner as in Example 7.
-Production of intermediate layer-
In Example 7, instead of adding 0.02% by mass of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA), pentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD PET-30) 0 An intermediate layer was provided in the same manner as in Example 7 except that 0.07% by mass was added.
-Production of protective layer-
In Example 7, instead of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD D-310) as a protective layer composition, dipentaerythritol acrylate (manufactured by Negami Industrial Co., Ltd., UN-3320HA) was used. A protective layer was provided in the same manner as in Example 7 except that it was used.
-Production of back layer-
A back layer was provided in the same manner as in Example 7 to produce a reversible thermosensitive recording medium.

(Example 12)
<Preparation of reversible thermosensitive recording medium>
-Production of heat insulation layer-
In Example 9, Example 9 was used except that a white turbid polyester film (Teijin DuPont, Tetron film U3L99W) having a thickness of 75 μm was used instead of a 188 μm thick white turbid polyester film (Tetron film, Tetoron film). In the same manner as above, a heat insulating layer was provided.
-Preparation of thermosensitive recording layer-
A thermosensitive recording layer was provided in the same manner as in Example 8.
-Production of intermediate layer-
In Example 8, instead of 0.02% by mass of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA), pentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD PET-30) 0 An intermediate layer was provided in the same manner as in Example 8 except that 0.08% by mass was added.
-Production of protective layer-
In Example 8, instead of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD D-310) as a protective layer composition, dipentaerythritol acrylate (manufactured by Negami Industrial Co., Ltd., UN-3320HA) was used. A protective layer was provided in the same manner as in Example 8 except that it was used.
-Production of back layer-
A back layer was provided in the same manner as in Example 8 to produce a reversible thermosensitive recording medium.

(Comparative Example 1)
In Example 1, 4 parts by mass of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA) and dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPCA-60) 21 in Example 1 A reversible thermosensitive recording medium was prepared in the same manner as in Example 1 except that 25 parts by mass of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA) was used instead of parts by mass.

(Comparative Example 2)
In Example 2, 7 parts by mass of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA) and dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPEA-12) 18 A reversible thermosensitive recording medium was prepared in the same manner as in Example 2 except that 25 parts by mass of dipentaerythritol acrylate (manufactured by Negami Kogyo Co., Ltd., UN-3320HA) was used instead of parts by mass.

(Comparative Example 3)
In Example 3, 9 parts by mass of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA) and 16 parts by mass of pentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD THE-330) 4 parts by mass of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA) and 21 parts by mass of dipentaerythritol acrylate (manufactured by Negami Industrial Co., Ltd., UN-3320HA) were used instead of parts. Produced a reversible thermosensitive recording medium in the same manner as in Example 3.

(Comparative Example 4)
In Example 4, 12 parts by mass of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA) and 13 parts by mass of pentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD TPA-330) A reversible thermosensitive recording medium was produced in the same manner as in Example 4 except that 25 parts by mass of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPCA-60) was used instead of the parts.

(Comparative Example 5)
In Example 3, 9 parts by mass of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA) and 16 parts by mass of pentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD THE-330) 9 parts by mass of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPCA-60) and 16 parts by mass of dipentaerythritol acrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPCA-12) were used instead of the parts. Produced a reversible thermosensitive recording medium in the same manner as in Example 3.

  Next, Examples 1 to 12 and Comparative Examples 1 to 5 are summarized as shown in Tables 2-1 to 2-3 below.

  Next, the produced reversible thermosensitive recording media were subjected to cracking, curling, printability, adhesion, transportability, chemical resistance, and repeated erasure printing test as follows. The results are shown in Table 3.

<Crack>
Each produced reversible thermosensitive recording medium was wound around an iron cylinder having a diameter of 4 mm, and the surface of the recording medium was evaluated by visual observation, and evaluated based on the following evaluation criteria.
〔Evaluation criteria〕
A: The surface of the reversible thermosensitive recording medium is normal and has no cracks. ○: A slight crack is generated on the surface of the reversible thermosensitive recording medium. Large cracks occurred and the surface was destroyed

<Curl>
Each reversible thermosensitive recording medium produced was evaluated for curl of the recording medium with a ruler after 100 times of repeated erasing and printing using a sheet printer (Prepeat 3100) manufactured by Sanwa New Tech Co., Ltd. Evaluation was performed based on the evaluation criteria.
〔Evaluation criteria〕
A: The curl of the reversible thermosensitive recording medium was hardly observed. O: The curl of the reversible thermosensitive recording medium was less than 1 to 5 mm. Δ: The curl of the reversible thermosensitive recording medium was less than 5 to 10 mm. The thermal recording medium curl was 10mm or more

<Printability>
On each reversible thermosensitive recording medium, using an RI tester, 1 μm of OP varnish (manufactured by T & K TOKA, UP2L) is formed, and the printing condition when printing is performed by crosslinking with an 80 w / cm UV lamp. Was evaluated based on the following evaluation criteria.
〔Evaluation criteria〕
○: Applied as intended for printing and did not peel off even when scratched with a nail △: Applied as intended for printing, but removed when scratched with a nail ×: Could not be printed

<Adhesiveness>
Using a cross-cut tester on each reversible thermosensitive recording medium produced, a scratch was made on the surface of the medium with a cutter blade, and cello tape (registered trademark) (manufactured by Nichiban Co., Ltd.) was applied to the scratch, and the peeled off The degree of peeling of the protective layer was evaluated based on the following evaluation criteria.
◎: No peeling ○: Peeling within 90% △: Peeling within 50% ×: Peeling over 50%

<Transportability>
Each of the produced reversible thermosensitive recording media was subjected to repeated erasing and printing 100 times using a PCC card printer (R28000), and the surface of the recording medium was visually evaluated. Based on the following evaluation criteria evaluated.
〔Evaluation criteria〕
○: The surface of the recording medium is normal and free of defects. △: The surface of the recording medium is flawed.

<Durability>
Each reversible thermosensitive recording medium produced was subjected to repeated image formation of erasure and printing 100 times using a card printer (R28000) manufactured by PCC, and then the color developing portion was measured with a Macbeth densitometer RD-914 and X-Rite 938. The image density value of the decolored part was measured.

From the results in Table 3, in the protective layer, one of the two acrylate compounds is an acrylate compound (A) in which a pentaerythritol group or a dipentaerythritol group and a polymerizable group having an ester bond are directly bonded, Example in which the other contains an acrylate compound (B) having a hydrocarbon group which may have a substituent having an ester bond between a pentaerythritol group or a dipentaerythritol group and a polymerizable group having an ester bond It was confirmed that Nos. 1 to 12 had excellent effects in all of cracking, curling, printability, adhesiveness, transportability, chemical resistance, and repeated erasure printing test as compared with Comparative Examples 1 to 5.

  The reversible thermosensitive recording medium of the present invention is widely used in a sheet size larger than the card size from a card shape, and can be used for general documents, process management instructions, and the like. Therefore, the reversible thermosensitive recording medium of the present invention can be widely used for large screens and various displays such as entrance / exit tickets, frozen food containers, stickers for industrial products, various chemical containers, logistics management applications, manufacturing process management applications, etc. Can do.

FIG. 1 is a diagram showing color development / decoloration characteristics (color development and decoloration phenomenon) in the reversible thermosensitive recording medium of the present invention. FIG. 2 is a schematic diagram illustrating an example of an RF-ID tag. FIG. 3 is a schematic view showing a state in which an RF-ID tag is bonded to the back layer surface side of the reversible thermosensitive recording medium. FIG. 4A is a schematic diagram illustrating an example of an industrial rewritable sheet (reversible thermosensitive recording medium). FIG. 4B is a schematic diagram illustrating the back surface of FIG. 4A. FIG. 5 is a schematic view showing a method of using an industrial rewritable sheet (reversible thermosensitive recording medium). FIG. 6 is a diagram showing an example of a thermocompression bonding process between the reversible thermosensitive recording label and the base sheet in the present invention. FIG. 7 is a diagram showing another example of the thermocompression bonding process of the reversible thermosensitive recording label and the base sheet according to the present invention. FIG. 8 is a schematic view showing an example of a state in which the reversible thermosensitive recording medium label of the present invention is stuck on an MD disk cartridge. FIG. 9 is a schematic view showing an example of a state in which the reversible thermosensitive recording medium label of the present invention is stuck on an optical information recording medium (CD-RW). FIG. 10 is a schematic cross-sectional view showing an example of a state in which the reversible thermosensitive recording medium label of the present invention is stuck on an optical information recording medium (CD-RW). FIG. 11 is a schematic diagram showing an example of a state in which the reversible thermosensitive recording medium label of the present invention is attached to a video cassette. FIG. 12 is a schematic sectional view showing an example of the layer structure of the reversible thermosensitive recording medium of the present invention. FIG. 13 is a schematic sectional view showing another example of the layer structure of the reversible thermosensitive recording medium of the present invention. FIG. 14A is a schematic view of the surface side of an example of the reversible thermosensitive recording medium of the present invention processed into a card shape. FIG. 14B is a schematic diagram of the back side of FIG. 14A. FIG. 15A is a schematic view of an example in which an example of the reversible thermosensitive recording medium of the present invention is processed into another card shape. FIG. 15B is a schematic view of an IC chip embedded in the IC chip recess of FIG. 15A. FIG. 16A is a schematic configuration block diagram showing an integrated circuit. FIG. 16B is a schematic diagram showing that the RAM includes a plurality of storage areas. FIG. 17 is a schematic diagram showing an example of an image processing apparatus used in the image processing method of the present invention. FIG. 18 is a schematic diagram showing another example of an image processing apparatus used in the image processing method of the present invention. FIG. 19 is a schematic diagram showing still another example of an image processing apparatus used in the image processing method of the present invention. FIG. 20A is a schematic diagram of an image processing apparatus when a surface image is erased by a ceramic heater and an image is formed by a thermal head. FIG. 20B is a schematic diagram illustrating an example of the image processing apparatus of the present 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 10 Reversible thermosensitive recording label 11 Support body 13 Thermal layer 14 Intermediate layer 15 Protective layer 16 Back layer 21 Reversible Reactive recording card 22 Rewrite recording unit 23 Print display unit 24 Back layer 25 Dimple unit 26 Rewrite recording unit 30 Entrance / exit 31 Transport roller 32 Guide roller 33 Sensor 34 Magnetic head 34c Control means 35 Platen roller 36 Guide roller 37 Transport roller 38 Ceramic heater 38c Ceramic heater control means 39 Guide roller 40 Conveying roller 43 Sensor 43a Sensor 44 Platen roller 45 Conveying roller 46 Conveying roller 47 Conveying roller 48 Conveying belt 49b Conveying path 50 Conveying path 51 Sensor 52 Plastic Ten roller 53 Thermal head 53c Thermal head control means 55a Conveyance path switching means 55b Conveyance path switching means 56a Conveyance path 56b Conveyance path 57a Limit switch 57b Limit switch 58 Conveyance belt 59 Conveyance roller 60 Guide roller 61 Exit 70 MD disk cartridge 71 CD-RW
72 Video cassette 81 IC chip 82 Antenna 85 RF-ID tag 90 Industrial rewritable sheet (reversible thermosensitive recording member)
91 Display unit 92 Bar code 94 Ceramic heater 95 Thermal head 96 Heat roller 97 Paper feed tray 98 Reversible thermosensitive recording medium (rewritable sheet)
99 RF-ID reader / writer 100 Image processing apparatus 101 Protective layer 102 Thermal layer 103 Support body 104 Back layer 105 Adhesive layer or adhesive layer 106 Intermediate layer 107 Reflective heat dissipation layer 108 Second dielectric layer 109 Optical information storage layer 110 First 1 dielectric layer 111 substrate 112 hard coat layer 231 wafer 232 wafer substrate 233 integrated circuit 234 contact terminal 235 CPU
236 ROM
237 RAM
238 I / O interface 239a to 239g Storage area

Claims (24)

In a reversible thermosensitive recording medium having a support, a thermosensitive recording layer on the support, and a protective layer on the thermosensitive recording layer,
The thermosensitive recording layer contains an electron-donating color-forming compound and an electron-accepting compound, and the color tone reversibly changes depending on the temperature,
The reversible thermosensitive recording medium, wherein the protective layer contains a polymer of a composition containing two acrylate compounds selected from an acrylate compound having a pentaerythritol group and an acrylate compound having a dipentaerythritol group. . Of the two acrylate compounds, one is an acrylate compound (A) in which either a pentaerythritol group or a dipentaerythritol group and a polymerizable group having an ester bond are directly bonded.
The other is an acrylate compound having a chain hydrocarbon group that may have a substituent having an ester bond between either a pentaerythritol group or a dipentaerythritol group and a polymerizable group having an ester bond ( The reversible thermosensitive recording medium according to claim 1, which is B).   The reversible composition according to claim 2, wherein the blending mass ratio of the two acrylate compounds (A) and (B) is (A) / (B) = 1.0 / 9.0 to 5.0 / 5.0. Sexual thermal recording medium. The reversible thermosensitive recording medium according to any one of claims 1 to 3, wherein the two acrylate compounds are represented by the following structural formulas (1) and (2).
However, in the structural formulas (1) and (2), X represents a pentaerythritol group or a dipentaerythritol group. Y _{is, -CH 2 O -, - CH} 2 CH 2 O -, - CH 2 CH 2 CH 2 O -, - CH 2 CH 2 CH 2 CH 2 O -, - CH 2 CH 2 CH 2 CH 2 CH 2 _{O -, - CH 2 CH (} CH 3) O-, or _{-CO-CH 2 CH 2 CH 2} CH 2 represent a _CH 2 O-. Z represents -H or -CO-CH = CH _2,. a represents 1 to 5, b represents 1 to 5, and c represents 1 to 12, respectively. The reversible thermosensitive recording medium according to any one of claims 1 to 4, wherein the electron-accepting compound is a phenol compound represented by any one of the following structural formulas (3) and (4).
However, in said structural formula (3), X and Y represent the bivalent organic group containing a hetero atom. R ³ represents a divalent hydrocarbon group which may have a substituent. R ⁴ represents a monovalent hydrocarbon group which may have a substituent. n represents an integer of 1 to 3, m represents an integer of 1 to 20, and r represents an integer of 0 to 3.
However, in said Structural Formula (4), n represents the integer of 1-3. X represents a divalent organic group containing a hetero atom. R ³ represents a divalent hydrocarbon group which may have a substituent. R ⁴ represents a monovalent hydrocarbon group which may have a substituent.   The reversible thermosensitive recording medium according to any one of claims 1 to 5, wherein the layer in contact with the support-side surface of the protective layer contains an acrylate compound having either a pentaerythritol group or a dipentaerythritol group. The reversible thermosensitive recording medium according to claim 6, wherein the acrylate compound having either a pentaerythritol group or a dipentaerythritol group is an acrylate compound (C) represented by the following structural formula (5).
However, in said structural formula (5), X represents a pentaerythritol group or a dipentaerythritol group. a represents 1 to 5, and b represents 1 to 5.   The reversible feeling according to claim 7, wherein the content of the acrylate compound (C) is a dry mass of the acrylate compound (C) / a dry mass of the layer containing the acrylate compound (C) = 0.01 to 0.10. Thermal recording medium.   The reversible thermosensitive recording medium according to any one of claims 6 to 8, wherein the layer in contact with the surface on the support side of the protective layer is a thermosensitive recording layer.   The reversible thermosensitive recording medium according to any one of claims 6 to 8, wherein the layer in contact with the support-side surface of the protective layer is an intermediate layer between the thermosensitive recording layer and the protective layer.   The reversible thermosensitive recording medium according to any one of claims 1 to 10, further comprising a heat insulating layer containing at least hollow particles between the thermosensitive recording layer and the support.   The hollow particles have a hollow ratio of 70% or more, the maximum particle diameter (D100) of the hollow particles is 5.0 to 10.0 μm, and the ratio (D100 / D50) to the 50% frequency particle diameter (D50) The reversible thermosensitive recording medium according to claim 11, wherein the material forming the hollow particles is a copolymer having at least one of acrylonitrile and methacrylonitrile as a monomer unit.   The reversible thermosensitive recording medium according to any one of claims 1 to 12, wherein the reversible thermosensitive recording medium is processed into any one of a label shape, a sheet shape, and a roll shape.   14. The irreversible visible information and / or printable portion is provided on at least a part of at least one of the image forming surface and the opposite surface of the reversible thermosensitive recording medium. A reversible thermosensitive recording medium according to claim 1.   15. A reversible thermosensitive recording comprising the adhesive layer and the pressure-sensitive adhesive layer on the surface opposite to the image forming surface of the reversible thermosensitive recording medium according to claim 1. label.   A reversible thermosensitive recording member comprising an information storage unit and a reversible display unit, wherein the reversible display unit comprises the reversible thermosensitive recording medium according to claim 1.   The reversible thermosensitive sensor according to claim 16, wherein the information recording unit is selected from a magnetic thermosensitive recording layer, a magnetic stripe, an IC memory, an optical memory, a hologram, an RF-ID tag card, a disk, a disk cartridge, and a tape cassette. Recording member.   Image forming means for forming an image on the reversible thermosensitive recording medium by heating the reversible thermosensitive recording medium, and image erasing for erasing the image formed on the reversible thermosensitive recording medium by heating the reversible thermosensitive recording medium An image processing apparatus comprising: the reversible thermosensitive recording medium according to any one of claims 1 to 14;   The image processing apparatus according to claim 18, wherein the image forming unit is a thermal head or a laser irradiation apparatus.   The image processing apparatus according to claim 18, wherein the image erasing unit is any one selected from a thermal head, a ceramic heater, a heat roll, a hot stamp, a heat block, and a laser irradiation apparatus.   An image forming process for forming an image on the reversible thermosensitive recording medium by heating the reversible thermosensitive recording medium, and an image for erasing the image formed on the reversible thermosensitive recording medium by heating the reversible thermosensitive recording medium 15. An image processing method comprising at least one of erasing steps, wherein the reversible thermosensitive recording medium is the reversible thermosensitive recording medium according to any one of claims 1 to 14.   The image processing method according to claim 21, wherein the image is formed by using either a thermal head or a laser irradiation device.   The image processing method according to any one of claims 21 to 22, wherein the image is erased using any one selected from a thermal head, a ceramic heater, a heat roll, a hot stamp, a heat block, and a laser irradiation device.   24. The image processing method according to claim 22, further comprising a step of forming a new image while erasing the image using a thermal head.