JP2006076095A - Reversible thermosensitive recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reversible thermosensitive recording medium, which has a high adhesion with respect to diversifying laminating base materials such as PVC, PET-G and acrylic even under low temperature environments and, repeated durability at the same time, has an adhesive bond layer, which does not block to the surface layer of a recording medium, a member with an information storing part, in which the reversible thermosensitive recording medium is employed, an image processing method and an image processing device. <P>SOLUTION: In the reversible thermosensitive recording layer, on a support of which, the heat reversible recording layer, the color tone of which is reversibly changed by heat, is provided and the adhesive bond layer is provided on the opposite side of the support, the adhesive bond layer includes crosslinking type spherical particles. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a reversible thermosensitive recording medium capable of forming and erasing an image by controlling thermal energy.

In recent years, attention has been focused on a reversible thermosensitive recording medium which can perform temporary image formation and can erase the image when it is no longer needed. As a representative example, a developer such as an organic phosphate compound, an aliphatic carboxylic acid compound or a phenol compound having a long-chain aliphatic hydrocarbon group and a color developer such as a leuco dye are dispersed in a resin matrix. Reversible thermosensitive recording media are known (for example, Patent Documents 1 and 2).
Many of such reversible thermosensitive recording media (hereinafter sometimes simply referred to as “recording media”) use a PET film having a magnetic recording layer as a support, and are mainly used as point cards in the market. On the other hand, a thermoreversible recording layer is provided on a thin support, and there is an adhesive layer on the opposite side of the support, and it is laminated on various substrates by heat and pressure as a reversible thermosensitive recording medium. There are many ways to use it. For example, Patent Documents 3 and 4 have a reversible thermosensitive recording sheet with an adhesive layer, Patent Document 5 has a reversible thermosensitive recording medium with an adhesive layer, Patent Document 6 has a reversible thermosensitive recording film, and Patent Document 7 has. Discloses a reversible thermosensitive recording card, and Patent Document 8 discloses a reversible thermosensitive card recording medium provided with an adhesive layer.
However, cards made by laminating reversible thermosensitive recording media composed of the adhesive materials used in these materials with heat and pressure are used for diversifying substrates for bonding (vinyl chloride sheet (PVC) and amorphous). Adhesive strength to copolyester (PET-G), acrylic, etc.) is poor, especially when the adhesive strength decreases in a low temperature environment of 5 ° C. or lower, and repeated erasure printing is repeated in that environment. And pressure will cause separation between the substrate and the adhesive layer surface, resulting in defects in erasing and printing, making it impossible to demonstrate the original repeated use ability of the media, or peeling from the edge of the card. As this increases, peeling occurs and it becomes impossible to use repeatedly.
On the other hand, there are adhesives that can maintain the adhesive force in a low-temperature environment, but this has the disadvantage that it is easy to stick to the surface layer of the recording medium, and when the adhesive layer and the outermost surface layer are in contact with each other When heat and pressure are applied, blocking occurs in which the layers stick to each other. When such a phenomenon occurs, there is a problem that it cannot be used as a reversible thermosensitive recording medium.
In order to deal with such problems of the adhesive layer, Patent Documents 9 and 10 propose a technique for improving low-temperature adhesiveness. However, for use as a reversible thermosensitive recording medium, repeated erasure printing in a low-temperature environment is proposed. Durability and blocking resistance are insufficient.
In addition, Patent Document 11 proposes an adhesive layer containing an inorganic filler for the purpose of improving adhesive strength and blocking for heat-sensitive adhesive labels (thermoactive adhesive labels). It is insufficient as a recording medium that requires high performance.

JP-A-5-124360 Japanese Patent Laid-Open No. 6-210954 JP 2000-94866 A JP 2003-80853 A Japanese Patent Laid-Open No. 2000-251042 JP 2001-63228 A JP 2002-103654 A JP 2000-263934 A JP 2001-63228 A JP 2001-279226 A JP 2002-114953 A

An object of the present invention is to have a high adhesive force to a diversifying bonding substrate such as PVC, PET-G, and acrylic even in a low temperature environment, and has a repeated durability, and a surface layer of a recording medium It is an object of the present invention to provide a reversible thermosensitive recording medium having a non-blocking adhesive layer.
Another object of the present invention is to provide a member having an information storage section using such a reversible thermosensitive recording medium, an image processing method, and an image processing apparatus.

  As a result of studies to solve these problems, the present inventors have used a specific filler for the adhesive layer, so that there is no liquid aggregation or filter clogging in the adhesive layer coating production process, and uniform coating is achieved. In terms of quality, it has been found that a reversible thermosensitive recording medium having both repeated durability (adhesiveness) in a low temperature environment for various substrates and blocking resistance to the outermost surface layer of the recording medium can be obtained. It came to complete.

The invention of claim 1 provides a reversible thermosensitive recording medium having a thermoreversible recording layer having a color tone reversibly changed by heat on a support, and having an adhesive layer on the opposite surface of the support. A reversible thermosensitive recording medium comprising cross-linked spherical particles.
A second aspect of the present invention is the reversible thermosensitive recording medium according to the first aspect, wherein the cross-linked spherical particles are an acrylic resin.
The invention according to claim 3 is characterized in that the particle size distribution of the cross-linked spherical particles is a particle size distribution in which the particles are aggregated within a range of ± 10% with respect to the average particle size. It is a reversible thermosensitive recording medium.
A fourth aspect of the present invention is the reversible thermosensitive recording medium according to any one of the first to third aspects, wherein a particle diameter of the crosslinked spherical particles is larger than a thickness of the adhesive layer.
The invention according to claim 5 is the reversible thermosensitive recording medium according to any one of claims 1 to 4, wherein the crosslinked spherical particles have an average particle diameter of 5 to 20 μm.
The invention of claim 6 is characterized in that the adhesive layer contains at least two kinds of resins having a difference in glass transition point (Tg) and a crosslinking agent having an isocyanate group. The reversible thermosensitive recording medium described.
A seventh aspect of the present invention is the reversible thermosensitive recording medium according to the sixth aspect, wherein the difference between the glass transition points (Tg) of the two kinds of resins contained in the adhesive layer is 30 ° C. or more. .
In the invention of claim 8, the two types of resins contained in the adhesive layer are a resin having a glass transition point (Tg) of −30 to 10 ° C. and a resin having a glass transition point (Tg) of 30 to 80 ° C. The reversible thermosensitive recording medium according to claim 6, wherein the reversible thermosensitive recording medium is provided.
The invention according to claim 9 is characterized in that, in the two types of resins contained in the adhesive layer, the ratio of the resin having a glass transition point (Tg) of −30 to 10 ° C. is 50 to 95% by mass. The reversible thermosensitive recording medium according to claim 8.
The invention of claim 10 is characterized in that the cross-linked spherical particles are contained in a proportion of 5 to 30% by mass with respect to the resin contained in the adhesive layer. This is a heat-sensitive recording medium.
The invention according to claim 11 includes an information storage unit and a reversible display unit, and the reversible display unit includes at least the thermoreversible thermosensitive recording medium according to any one of claims 1 to 10. It is a member which has a part.
The invention according to claim 12 is the member according to claim 11, wherein the member having the information storage section is a card, a disk, a disk cartridge, or a tape cassette.
According to a thirteenth aspect of the present invention, the reversible thermosensitive recording medium according to any one of the first to tenth aspects or the thermoreversible recording layer in the member having the information storage section according to the eleventh or twelfth aspect is heated. An image processing method characterized by forming and / or erasing an image.
A fourteenth aspect of the invention is the image processing method according to the thirteenth aspect, wherein an image is formed using a thermal head.
A fifteenth aspect of the present invention is the image processing method according to the thirteenth aspect, wherein the image is erased using a thermal head or a ceramic heater.
The invention according to claim 16 is equipped with the reversible thermosensitive recording medium according to any one of claims 1 to 10 or the member having the information storage section according to claim 11 or 12, and forms and / or erases an image. An image processing apparatus comprising means for performing the above.
The invention according to claim 17 is the image processing apparatus according to claim 16, wherein the image forming means is a thermal head.
The invention according to claim 18 is the image processing apparatus according to claim 16, wherein the image erasing means is a thermal head or a ceramic heater.

  According to the present invention, even in a low temperature environment, the adhesive layer has a high adhesive force with respect to diversifying substrates for bonding such as PVC, PET-G, and acrylic, has repeated durability, and has a recording medium surface layer. There are provided a reversible thermosensitive recording medium having a non-blocking adhesive layer, a member having an information storage unit using the reversible thermosensitive recording medium, an image processing method, and an image processing apparatus.

Hereinafter, the reversible thermosensitive recording medium of the present invention will be described in detail.
The reversible thermosensitive recording medium of the present invention is a reversible thermosensitive recording medium having a thermoreversible recording layer having a color tone reversibly changed by heat on a support, and having an adhesive layer on the opposite surface of the support. The adhesive layer is characterized by containing crosslinked spherical particles as a specific filler.
The specific filler contained in the adhesive layer achieves the above-mentioned purpose, is dispersed as uniformly as possible in the adhesive layer, and takes a form that appears as uniformly as possible from the surface of the adhesive layer, or has a print on the base From the standpoint of not concealing the printed pattern as much as possible in some cases, the shape is preferably spherical (including an ellipse), and more preferably close to a true sphere. The particle size distribution of the crosslinked spherical particles as the specific filler is preferably as sharp as possible. For example, the particle size distribution is such that the particles aggregate within a range of ± 10% with respect to the average particle size. Preferred (hereinafter referred to as monodisperse particles).

  In addition, although the reason is not clear, in the case of an adhesive coating solution containing toluene as a solvent, a crosslinked type having excellent solvent resistance is preferable, and a crosslinked spherical acrylic (in which the filler itself hardly forms an aggregate in the coating solution ( PMMA) monodisperse particles are particularly preferred.

  Further, the crosslinked spherical particles preferably have a particle size larger than the adhesive layer thickness. Thereby, adhesive force, blocking resistance, and coating quality can be improved. In particular, the blocking resistance is improved. In this embodiment, in order to allow a part of the cross-linked spherical particles to appear on the surface of the adhesive layer while maintaining a certain film thickness in maintaining the adhesive force to various substrates, the particle size of the cross-linked spherical particles Is preferably in the range of 5 to 20 μm. However, if the addition amount of the cross-linked spherical particles is too large, the adhesive strength is lowered, or there is a problem in the concealability when being bonded to a printed substrate or the like. Therefore, the content of the cross-linked spherical particles is desirably 5 to 30% by mass with respect to the resin component of the adhesive layer, preferably 10 to 20% by mass, and more preferably 10 to 15% by mass. . Silicone particles and other organic resin particles are also known as spherical fillers, but they lack stability in the solvent and form aggregates, so that the uniformity of the coated surface is poor, or in the manufacturing process There were a lot of things that caused various troubles. Inorganic fillers are also commonly used as anti-blocking agents, but the shape is indefinite, or because it has a certain amount of oil absorption, it may cause an increase in the viscosity of the adhesive coating solution. It was not possible to achieve a state in which a part of the filler appeared as uniformly as possible on the coated surface, and the adhesive strength, blocking, and coating quality could not be satisfied.

The adhesive layer preferably contains at least two types of resins having a difference in glass transition point (Tg) and a crosslinking agent having an isocyanate group. As a result, each resin has a function to increase the adhesive force and an anti-blocking function, and by adding a cross-linking agent, the resin is cross-linked to increase the molecular weight, thereby improving the adhesive force of the recording medium and in a low temperature environment. It is possible to obtain an effect of increasing the adhesive strength at the same time.
Furthermore, the difference in glass transition point (Tg) between the two types of resins contained in the adhesive layer is preferably 30 ° C. or higher. This difference is the difference in Tg between the resin that enhances adhesion and the resin that suppresses blocking. When the difference in glass transition point (Tg) is less than 30 ° C., the effects of both are lost, and there is adhesion but it is easy to block. Or, it is difficult to block, but the adhesive strength is low. That is, it may be difficult to achieve both repetitive durability and blocking performance in a low temperature environment. The difference in glass transition point (Tg) is more preferably 35 ° C. or more, and further preferably 45 ° C. or more.
The two kinds of resins are preferably resins having a glass transition point (Tg) of −30 to 10 ° C. and resins having a glass transition point (Tg) of 30 to 80 ° C. Resins having a low glass transition point (Tg) of −30 to 10 ° C. tend to have high adhesion to various substrates for bonding. However, there is a problem in that blocking occurs because the resin has tackiness and adhesion to the outermost surface of the reversible thermosensitive recording medium in a room temperature environment. On the other hand, a resin having a high Tg of 30 to 80 ° C. tends to have a lower adhesive force to the substrate for bonding than a resin having a low Tg, but has no tackiness in a normal temperature environment and has no blocking. Therefore, by mixing two or more types of resins having a low Tg and a resin having a high Tg, a balance between adhesive strength and blocking resistance can be obtained. However, it is difficult to solve the decrease in adhesive strength in a low-temperature environment only by mixing the resin, and it can be solved by blending a crosslinking agent having an isocyanate group. This is considered to be because crosslinking with a crosslinking agent increases the molecular weight of the resin, increases the adhesive strength, and maintains the adhesive strength in a low-temperature environment. In addition, the resin can be made into a thin film by being dissolved in a solvent and applied, but it cannot have a large molecular weight. Therefore, there is an effect that the molecular weight can be increased after coating by adding a crosslinking agent.
Here, in a resin having a low Tg, if the Tg is lower than −30 ° C., the tack property at room temperature is very strong and the blocking resistance is deteriorated, and if the resin is higher than 10 ° C., the adhesive strength may be reduced. There is. As the resin having a low Tg, Tg is more preferably −20 to 10 ° C., and further preferably −15 to 10 ° C. A resin having a high Tg and a temperature lower than 30 ° C. has a strong tackiness at room temperature, a strong blocking property, and an effect of mixing with a resin having a low Tg is lost. In addition, when Tg is higher than 80 ° C., the adhesive strength is lowered, and the softening temperature of the resin film is increased, so that the bonding (laminating) temperature with various base materials is increased, thereby obtaining sufficient adhesive strength. Can not be. The resin having a high Tg is more preferably 30 to 75 ° C, and further preferably 50 to 70 ° C.
Moreover, in two types of resin contained in the said adhesive layer, it is preferable that the ratio of resin which has a glass transition point (Tg) of -30-10 degreeC is 50-95 mass%. When it is lower than 50% by mass, the adhesive strength is lowered, and the repeated durability (adhesiveness) in a low temperature environment may be lowered. When it exceeds 95 mass%, blocking resistance will become low. The ratio of the resin having a low Tg is more preferably 60 to 80% by mass.

  As the blending of the crosslinking agent, when the isocyanate group is decreased, the crosslinking is insufficient, so that the decrease in the adhesive force in a low temperature environment cannot be suppressed, and the effect of adding the crosslinking agent is not seen. Therefore, for example, the blending of the crosslinking agent is preferably a molar ratio of 0.3 to 3.5 as the ratio of isocyanate group to hydroxyl group (NCO / OH). If it is less than 0.3, crosslinking is insufficient, so that a decrease in adhesive strength in a low temperature environment cannot be suppressed, and the effect of adding a crosslinking agent is not observed. On the other hand, if it is higher than 3.5, the curing of the resin film is promoted, the softening point of the whole coating film is increased, and lamination becomes impossible. NCO / OH is preferably 0.5 to 2.5, and more preferably 0.7 to 2.0.

  As the resin for the adhesive layer used in the reversible thermosensitive recording medium of the present invention, urea resin, melamine resin, phenol resin, epoxy resin, vinyl acetate resin, vinyl acetate-acrylic copolymer, ethylene-vinyl acetate copolymer, Acrylic resins, polyvinyl ether resins, vinyl chloride-vinyl acetate copolymers, polystyrene resins, polyester resins, polyurethane resins, polyamide resins, chlorinated polyolefin resins, polyvinyl butyral resins, acrylate esters Copolymers, methacrylic acid ester copolymers, natural rubber, cyanoacrylate resins, silicon resins and the like can be mentioned. In the present invention, it is desirable that the resin has a hydroxyl group at the terminal or side chain. For adhesion between PVC, PET-G, acrylic and PET film, polyester resins and polyurethane resins are preferable, and polyester resins are more preferable.

  As the crosslinking agent, an isocyanate curing agent is used. Specific examples of the isocyanate curing agent include hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), etc., and adduct types based on these trimethylolpropane, Examples include burette type, isocyanurate type, and blocked isocyanates. Among these, hexamethylene diisocyanate is particularly preferable, and this adduct type, burette type, and isocyanurate type are preferably used.

  Furthermore, an adhesive strength improving imparting agent can be added to the adhesive layer as long as the blocking resistance is not impaired. Specific examples thereof include terpene resins, aliphatic petroleum resins, aromatic petroleum resins, coumarone indene resins, styrene resins, rosin derivative resins, and the like.

  Furthermore, to improve the blocking resistance, wax such as polyethylene wax, carbana wax, silicone wax, silica, talc, calcium carbonate, zinc stearate, silicone resin fine particles, so as not to deteriorate the aggregation in the coating liquid. Fillers such as acrylic particles may be added. Moreover, you may add additives, such as a plasticizer and a flame retardant.

The film thickness of the adhesive layer composed of the above materials is preferably 1 to 20 μm. If it is thinner than 1 μm, sufficient adhesive force cannot be obtained, and if it is thicker than 20 μm, the thickness of the adhesive layer becomes too thick and the adhesive protrudes from the side of the medium during lamination, and the surface of the medium is soiled. It will cause a defect in erasure printing. More preferably, it is 2-15 micrometers, Most preferably, it is 5-15 micrometers.
An easy-adhesion layer, an intermediate layer, a cushion layer or the like for improving adhesiveness may be provided between the adhesive layer and the support. Moreover, you may surface-treat on a support body.

As the support, a tough plastic film excellent in heat resistance, tensile strength and the like can be applied. Examples thereof include polyethylene terephthalate (PET), polyethylene naphthalate, polyimide, polyphenylene sulfide, and the like. Among these, it is preferable to use a PET film.
Examples of the base material for bonding include a vinyl chloride resin (PVC), an amorphous copolyester resin (for example, PET-G), a polycarbonate resin, and the like, or a mixed sheet. Moreover, what laminated | stacked these base materials and processed the surface with acrylic resin etc. after that may be used.

There are two methods for providing an adhesive layer on a support: a solvent coating method in which a resin or the like is dissolved in a solvent and applied to a substrate, and a solventless coating method in which no solvent is interposed. In the present invention, the solvent coating method is preferably used. . This is because when two types of resins having a difference in glass transition point (Tg) and a crosslinking agent having an isocyanate group are used, the thickness of the adhesive layer formed by mixing and heating them is reduced, and after application This is because in order to perform the method of increasing the molecular weight by crosslinking, it is necessary to carry out by the solvent coating method of dissolving and applying in a solvent.
Specific examples of the solvent include water, alcohols, ketones, amides, ethers, glycol ethers, glycol ether acetates, esters, aromatic hydrocarbons, and aliphatic hydrocarbons. Etc.
The coating method in the present invention is not particularly limited, and 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 and other known coating methods, intaglio printing methods such as plate printing methods and gravure methods, offset lithographic printing methods, or screen plate making A known printing method such as a stencil printing method using a stencil can be used.

  As a method for drying / curing the adhesive layer, a curing process is performed after coating / drying. A thermostatic bath or the like may be used for a relatively short time at a relatively high temperature, or a heat treatment may be performed at a relatively low temperature for a long time. As specific conditions for the cross-linking reaction, it is preferable that the temperature is about 1 to 240 hours under a temperature condition of about 20 to 130 ° C. in terms of reactivity.

In order to bond (laminate) the reversible thermosensitive recording medium of the present invention to a bonding substrate, it is necessary to apply heat and pressure using a hot press machine or the like. In order to laminate, the above-mentioned bonding substrate is laminated, and the recording medium is stacked on the upper surface of the bonding substrate so that the adhesive layer surface is in contact with the substrate. 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 this core sheet, for example, a thickness of 250 μm And a core sheet obtained by laminating two white PET-G sheets, and a transparent PET-G having a thickness of 100 μm laminated as an oversheet on the front and back surfaces of the core sheet. As a method of affixing these base sheet and the reversible thermosensitive recording medium, as shown in FIG. 1 and FIG. 2, both are placed so as to face the mirror plate and sandwiched between the two mirror plates, There is a method of performing thermocompression bonding. FIG. 1 is a diagram showing an example of a thermocompression bonding process between a reversible thermosensitive recording medium and a base sheet in the present invention. In FIG. 1, a reversible thermosensitive recording medium 3 of the present invention is laminated on the upper surface of a base sheet 4 so that the adhesive layer surface of the recording medium 3 is in contact with the base sheet 4, two mirror plates 2 and a hot plate 1. It is sandwiched between and thermocompression bonded. FIG. 2 is a diagram showing another example of the thermocompression bonding process between the reversible thermosensitive recording medium and the base sheet in the present invention. In FIG. 2, the oversheet 7 is laminated on the front and back surfaces of the two laminated core sheets 6, and is further laminated on the upper surface of one oversheet 7 so that the adhesive layer surface of the recording medium 3 is in contact with the oversheet 7. The sheet is sandwiched between the mirror plate 2 and the hot plate 1 and thermocompression bonded.
As heat, it is preferable that it is 80-160 degreeC, More preferably, it is 90-150 degreeC, More preferably, it is 100-140 degreeC. Preferably the pressure is 5~50kgf / cm ^2, more preferably 10~30kgf / cm ^2. The temperature and pressure are selected depending on the bonding substrate used. In addition, when the heating temperature or pressure at the time of thermocompression bonding is lower than the above range, sufficient adhesion between the substrates for bonding and adhesion between the substrate and the thermoreversible thermosensitive recording medium cannot be obtained. Peeling occurs. On the other hand, when the temperature is higher than the above range, the base material for bonding is melted and deformed, or heat and pressure are applied to the reversible thermosensitive recording medium, and the print erasing characteristics are adversely affected. Such thermocompression bonding can be performed under the above-described conditions, for example, in a state of being held for less than 1 hour, preferably about 1 to 50 minutes. The holding time is merely an example, and is not particularly limited in the present invention.

The “thermo-reversible recording layer whose color tone changes reversibly” used in the reversible thermosensitive recording medium of the present invention is a material which causes a visible change reversibly due to a temperature change. Visible changes can be divided into color state changes and shape changes, but the present invention mainly uses materials that cause color state changes. The change in the color state includes changes in transmittance, reflectance, absorption wavelength, scattering degree, and the like, and an actual thermoreversible recording material displays by combining these changes. More specifically, any material can be used as long as the transparency and color tone are reversibly changed by heat. For example, the first color temperature is set at a first specific temperature higher than room temperature, and is higher than the first specific temperature. Heating at the second specific temperature and then cooling to the second color state can be mentioned. In particular, a material whose color state changes between the first specific temperature and the second specific temperature is preferably used.
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, Decolored at a specific temperature (Japanese Patent Laid-Open Nos. 4-224996, 4-247985, and 4-267190), become cloudy at a first specific temperature, and transparent at a second specific temperature What becomes a state (Japanese Patent Laid-Open No. 3-169590), which develops black, red, blue, etc. at a first specific temperature and decolorizes at a second specific temperature (Japanese Patent Laid-Open No. 2-188293, Japanese Patent No. 2-188294) and the like. Among these, a system in which an organic low molecular weight substance such as a higher fatty acid is dispersed in a resin matrix and a system using a leuco dye and a long-chain alkyl developer are particularly preferable.

As the leuco dye, one or more compounds used in this type of reversible thermosensitive recording medium can be used, and examples thereof include known dye precursors such as phthalide compounds, azaphthalide compounds, and fluorane compounds.
Representative examples of the long-chain alkyl developer are recording layers described in, for example, JP-A Nos. 5-124360, 6-210954, and 10-95175. The developer used here is a structure having a color developing ability for developing a leuco dye in the molecule, such as a phenolic hydroxyl group, a carboxylic acid group, or a phosphate group, and a structure that controls the cohesion between molecules, such as a long It is a compound having one or more structures in which chain hydrocarbon groups are linked. The linking moiety may be via a divalent or higher valent linking group containing a hetero atom, and the same linking group and / or aromatic group may be contained in the long-chain hydrocarbon group. Specific examples of such a reversible developer are described in, for example, JP-A-9-290563 and JP-A-11-188969, and one kind or a mixture of two or more kinds may be used.

In the thermoreversible recording layer, an additive for improving or controlling coating characteristics and coloring / decoloring characteristics can be used as necessary. These additives include, for example, surfactants, conductive agents, fillers, antioxidants, color stabilizers, and decolorization accelerators.
The thermoreversible recording layer is formed of a leuco dye, a developer, and various additives together with a binder resin. The resin used at this time only needs to bind these materials on the support, and conventionally known resins are used alone or in combination of two or more. Of these, resins that can be cured by heat, ultraviolet rays, electron beams, etc. are preferably used in order to improve durability during repeated use, and in particular, thermosetting resins using isocyanate compounds as a crosslinking agent, such as acrylic polyols. Resin, polyester polyol resin, polyurethane polyol resin, polyvinyl butyral resin, cellulose acetate propionate, cellulose acetate butyrate and other resins having groups that react with crosslinking agents, or monomers having groups that react with crosslinking agents and other monomers A resin obtained by copolymerization of is particularly preferably used. However, the present invention is not limited to these compounds. Further, when crosslinked, the gel fraction of the recording layer is preferably 30% or more. If it is lower than this, the crosslinked state is not sufficient and the durability is inferior. This value is more preferably 50% or more, and particularly preferably 70% or more. The ratio of the color developing component to the resin in the recording layer is preferably from 0.1 to 10 with respect to the color developing component 1, and if it is less than this, the thermal strength of the recording layer is insufficient, and if it exceeds this, the color density is lowered. Problem. Further, as a method for distinguishing whether the binder resin in the present invention is in a crosslinked state or in a non-crosslinked state, it can be distinguished by immersing the coating film in a highly soluble solvent. That is, the binder resin in the non-crosslinked state is dissolved in the solvent and does not remain in the solute.

  The curing agent is not particularly limited, but an isocyanate curing agent is preferably used. Specific examples of the isocyanate curing agent include hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), etc., and adduct types based on these trimethylolpropane, Examples include burette type, isocyanurate type, and blocked isocyanates. Among these, hexamethylene diisocyanate is particularly preferable, and this adduct type, burette type, and isocyanurate type are preferably used. However, the total amount of the curing agent may or may not undergo a crosslinking reaction. That is, an unreacted curing agent may be present. Since this type of crosslinking reaction proceeds over time, the presence of an unreacted curing agent does not indicate that the crosslinking reaction has progressed at all, but an unreacted curing agent is detected. This suggests that there is a resin in a crosslinked state. Furthermore, you may use the catalyst used for this kind of reaction as a crosslinking accelerator.

The thermoreversible recording layer is formed using a coating liquid prepared by uniformly mixing and dispersing a mixture of a leuco dye, a developer, various additives, a binder resin and a coating solvent. Specific examples of the solvent used for preparing the coating liquid include alcohols, ketones, ethers, glycol ethers, esters, aromatic hydrocarbons, aliphatic hydrocarbons and the like. Is not limited to these compounds.
The coating liquid can be prepared using a known coating liquid dispersing apparatus such as a paint shaker, a ball mill, an attritor, a three-roll mill, a keddy mill, a sand mill, a dyno mill, or a colloid mill. Moreover, each material may be disperse | distributed in a solvent using the said coating-liquid dispersion | distribution apparatus, and each may be disperse | distributed and mixed in a solvent individually. Further, it may be dissolved by heating and precipitated by rapid cooling or cooling.
There are no particular restrictions on the coating method, blade coating, wire bar coating, spray coating, air knife coating, bead coating, curtain coating, gravure coating, kiss coating, reverse roll coating, dip coating Known methods such as work and die coating can be used.

A protective layer may be provided on the recording layer. For the protective layer, an organic / inorganic filler, an ultraviolet absorber, a lubricant, a color pigment, and the like can be used together with the solvent and binder resin described above, and a coating film is prepared using the dispersing device and the coating method described above. Can do.
In order to improve the adhesion between the recording layer and the protective layer, to prevent the recording layer from being altered by the application of the protective layer, and to prevent the additives in the protective layer from being transferred to the recording layer, it is preferable to provide an intermediate layer therebetween. This can improve the storage stability of the color image. In addition, it is possible to prevent or reduce the oxidation of the color former and the developer in the recording layer by using a resin having low oxygen permeability for the protective layer and the intermediate layer installed on the recording layer. . The intermediate layer is mainly made of a resin and may contain a filler as necessary. Moreover, the ultraviolet absorber may be included. The thickness of the intermediate layer is preferably in the range of 0.1 to 20 μm, more preferably 0.3 to 10 μm. Moreover, content of the filler in an intermediate | middle layer is 1-95% in a volume fraction, More preferably, it is 5-75%. The organic ultraviolet absorber used in the protective layer may be contained in the intermediate layer, and the content thereof is preferably in the range of 0.5 to 10 parts by weight with respect to 100 parts by weight of the binder. As the solvent used in the intermediate layer coating liquid, the coating liquid dispersing device, the intermediate layer coating method, the intermediate layer drying / curing method, etc., known methods used in the recording layer and the protective layer may be used. it can. Further, an under layer may be provided under the intermediate layer in order to improve color development sensitivity and adhesion.

Specific examples of inorganic fillers include carbonates, silicates, metal oxides, sulfate compounds, and specific examples of organic fillers include silicone resins, cellulose resins, epoxy resins, nylon resins, phenol resins, polyurethanes. Examples include resins, urea resins, melamine resins, polyester resins, polycarbonate resins, styrene resins, acrylic resins, polyethylene resins, formaldehyde resins, polymethyl methacrylate resins, and the like. Specific examples of the ultraviolet absorber include compounds having a salicylate structure, a cyanoacrylate structure, a benzotriazole structure, a benzophenone structure, and the like. Specific examples of the lubricant include synthetic waxes, vegetable waxes, animal waxes, higher alcohols, higher fatty acids, higher fatty acid esters, amides and the like. However, the present invention is not limited to these compounds.
In order to enable laser recording, a photothermal conversion layer that absorbs laser light and converts the light into heat may be provided.

  The thermoreversible recording layer is colored / decolored by, for example, the process shown in FIG. First, when the temperature of the decolored state (A) is raised, the leuco dye and the developer are melt-mixed at a temperature T1 or higher, and color development occurs, resulting in a molten color state (B). 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. Thus, the recording layer can be erased by controlling the heating temperature and the cooling rate after heating.

Moreover, this invention provides the member which has an information storage part containing the said reversible thermosensitive recording medium. Furthermore, the present invention provides an image processing method and apparatus for forming and / or erasing an image by heating a thermoreversible recording layer in a reversible thermosensitive recording medium.
By providing both the reversible display unit created using the reversible thermosensitive recording medium of the present invention and the information storage unit, the information stored in the information storage unit is displayed on the reversible display unit. Information can be confirmed even without it, improving convenience. As the storage unit used at that time, a magnetic recording layer, an IC recording unit, an optical memory, or the like is preferably used.

  Further, the reversible thermosensitive recording medium of the present invention is processed into a roll shape, a sheet shape, and a ribbon shape, and is laminated in a form according to the intended use using them, specifically, a card, a disk, and a disk cartridge. Processed into tape cassettes. Cards processed into prepaid cards, point cards, commuter pass, and other transportation applications, process management FR-IDs, credit cards, etc. are processed into general document sizes such as A4 size. By using a printing / erasing device, the sheet-like material can be widely used not only for trial printing but also for circulation documents and conference materials.

In order to form a color image using the reversible thermosensitive recording medium of the present invention, the color image may be rapidly cooled after being heated above the color development temperature. Specifically, for example, when the recording layer is heated for a short time with a thermal head or laser light, the recording layer is locally heated, so that the heat is immediately diffused and abrupt cooling occurs, so that the colored state can be fixed. A suitable heating member is a thermal head.
On the other hand, in order to erase the color, it may be heated and cooled for a relatively long time using an appropriate heat source, or may be temporarily heated to a temperature slightly lower than the coloring temperature. When heated for a long time, the temperature of a wide range of the recording medium rises, and the subsequent cooling becomes slow. As a heating method in this case, a hot roller, a hot stamp, hot air, or the like may be used, or heating may be performed for a long time using a thermal head. Suitable heating members are thermal heads and ceramic heaters. In order to heat the recording layer to the color erasing temperature range, for example, the applied energy may be lowered slightly from the time of recording by adjusting the voltage applied to the thermal head and the pulse width. If this method is used, recording / erasing can be performed only by the thermal head, and so-called overwriting becomes possible. Of course, it can be erased by heating to a decoloring temperature range with a heat roller or a heat stamp.

  The reversible thermosensitive recording medium of the present invention may be used in combination with an irreversible thermosensitive recording layer. At this time, the color tone of each recording layer may be the same or different. In addition, a colored layer may be provided on a part or the entire surface of the reversible thermosensitive recording medium of the present invention by applying printing such as offset printing or gravure printing, or an arbitrary pattern by an inkjet printer, thermal transfer printer, 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 Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to these Examples.
The parts and% shown below are based on mass.

Example 1
-Support to be coated: Transparent polyester film with a thickness of 25 μm (Tetron film HPE manufactured by Teijin DuPont)
・ Recording layer-Adjustment of recording layer solution-
1) Developer (having the following structure): 3 parts

2) Dialkyl urea (Nippon Kasei Co., Ltd., Haclean SB) 1 part 3) Acrylic polyol 50% solution (Mitsubishi Rayon Co., Ltd., LR327) 9 parts 4) Methyl ethyl ketone 70 parts The above composition was averaged using a ball mill. The mixture was pulverized and dispersed to 1 μm.
5) 2-anilino-3-methyl-6dibutylaminofluorane 1 part 6) Isocyanate (manufactured by Nippon Polyurethane Co., Ltd., Coronate HL) 3 parts Add the above composition to the dispersion obtained by pulverizing and dispersing the developer, and stir well. A recording layer coating solution was prepared.

The recording layer coating solution having the above composition is applied onto a film on which the photothermal conversion layer and the concealing layer are applied using a wire bar, dried at 100 ° C. for 2 minutes, and then cured at 60 ° C. for 24 hours to obtain a film thickness of about 10 g. A recording layer of / m ² was provided.

Intermediate layer-Preparation of intermediate layer liquid-
1) Acrylic polyol resin 50% solution (Mitsubishi Rayon, LR327) 3 parts 2) Zinc oxide fine particle 30% dispersion (Sumitomo Cement, ZS303) 7) 3) Isocyanate (Nihon Polyurethane, Coronate HL) 1 .5 parts 4) methyl ethyl ketone 7 parts The above composition was added and stirred well to prepare an intermediate layer coating solution.
On the recording layer-coated film, an intermediate layer coating solution was coated with a wire bar, heated and dried at 90 ° C. for 1 minute, and then heated at 60 ° C. for 48 hours to form a coated film having a thickness of about 1 μm.

Protective layer-Adjustment of protective layer solution-
1) Pentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPHA)
3 parts 2) Urethane acrylate oligomer (Negami Kogyo Co., Ltd., Art Resin UN-3320HA)
3 parts 3) Acrylic ester of dipentaerythritol caprolactone (manufactured by Nippon Kayaku Co., Ltd., KAYARAD DPCA-120) 3 parts 4) silica (manufactured by Mizusawa Chemical Industry Co., Ltd., P-526) 1 part 5) Photopolymerization initiator (Japan) Ciba Geigy, Irgacure 184) 0.5 part 6) Isopropyl alcohol 11 parts The above composition was added and stirred well to prepare a protective layer coating solution.
A protective layer coating solution was coated on the recording layer and intermediate layer coated film with a wire bar, dried by heating, and then crosslinked with an 80 W / cm ultraviolet lamp to form a coating film having a thickness of about 3 μm.

Adhesive layer-Adjustment of adhesive layer solution-
1) Saturated polyester resin (solid content 30%, toluene / MEK = 8/2: Tg = 40 ° C.)
30 parts 2) HDI isocyanate crosslinking agent (solid content 75%) 0.9 part 3) Toluene 56 parts 4) Methyl ethyl ketone 14 parts 5) Polyhydric alcohol fatty acid ester (manufactured by Riken Vitamin Co., Ltd., SL-02) 0.6 parts 6) Cross-linked spherical acrylic monodisperse particles (particle size 15 μm, particle size distribution 13.5 to 16.5 μm) 0.9 parts The above composition was added and stirred well to prepare an adhesive layer coating solution.
An adhesive layer coating solution is applied to the opposite side of the recording layer, intermediate layer and protective layer coated film with a wire bar, dried at 100 ° C. for 2 minutes, and then heated at 50 ° C. for 48 hours to form a coated film having a thickness of about 10 μm. Created.

(Example 2)
Except for the formation of the adhesive layer, the same as Example 1.
Adhesive layer-Adjustment of adhesive layer solution-
1) Saturated polyester resin (solid content 30%, toluene / MEK = 8/2: Tg = 5.5 ° C.)
24 parts 2) saturated polyester resin (solid content 30%, toluene / MEK = 8/2: Tg = 65 ° C.)
6 parts 3) HDI-based isocyanate crosslinking agent (solid content 75%) 0.9 part 4) Toluene 56 parts 5) Methyl ethyl ketone 14 parts 6) Polyhydric alcohol fatty acid ester (manufactured by Riken Vitamin Co., Ltd., SL-02) 0.6 part 7) Cross-linked spherical acrylic monodisperse particles (particle size: 15 μm, particle size distribution: 13.5 to 16.5 μm) 0.9 parts The above composition was added and stirred well to prepare an adhesive layer coating solution.
An adhesive layer coating solution is applied to the opposite side of the recording layer, intermediate layer and protective layer coated film with a wire bar, dried at 100 ° C. for 2 minutes, and then heated at 50 ° C. for 48 hours to form a coated film having a thickness of about 10 μm. Created.

(Example 3)
Except for the formation of the adhesive layer, the same as Example 1.
Adhesive layer-Adjustment of adhesive layer solution-
1) Saturated polyester resin (solid content 30%, toluene / MEK = 8/2: Tg = 5.5 ° C.)
21 parts 2) saturated polyester resin (solid content 30%, toluene / MEK = 8/2: Tg = 65 ° C.)
9 parts 3) HDI isocyanate crosslinking agent (solid content 75%) 0.9 part 4) Toluene 56 parts 5) Methyl ethyl ketone 14 parts 6) Polyhydric alcohol fatty acid ester (manufactured by Riken Vitamin Co., Ltd., SL-02) 0.6 parts 7) Cross-linked spherical acrylic monodisperse particles (particle size 15 μm, particle size distribution 13.5 to 16.5 μm) 2.5 parts The above composition was added and stirred well to prepare an adhesive layer coating solution.
An adhesive layer coating solution is applied to the opposite side of the recording layer, intermediate layer, and protective layer coated film with a wire bar, heated and dried at 100 ° C. for 2 minutes, and then heated at 50 ° C. for 48 hours to form a coated film having a thickness of about 10 μm. Created.

Example 4
Except for the formation of the adhesive layer, the same as Example 1.
Adhesive layer-Adjustment of adhesive layer solution-
1) Water-soluble saturated polyester resin (solid content 30%, Tg = −10 ° C.) 18 parts 2) Water-soluble saturated polyester resin (solid content 30%, Tg = 35 ° C.) 12 parts 3) HDI isocyanate crosslinking agent (solid 1.5 parts 4) Polyhydric alcohol fatty acid ester (manufactured by Riken Vitamin Co., SL-02) 0.6 part 5) Cross-linked spherical acrylic monodisperse particles (particle size 15 μm, particle size distribution 13.5 to 16.5 μm) 0 .9 parts The above composition was added and stirred well to prepare an adhesive layer coating solution.
An adhesive layer coating solution is applied to the opposite side of the recording layer, intermediate layer, and protective layer coated film with a wire bar, heated and dried at 100 ° C. for 2 minutes, and then heated at 50 ° C. for 48 hours to form a coated film having a thickness of about 10 μm. Created.

(Example 5)
A light reflecting layer was provided by vacuum-depositing about 400 liters of Al on a 25 μm thick transparent polyester film (Tetron Film HPE, manufactured by Teijin DuPont). On top of that, 10 parts of vinyl chloride-vinyl acetate-phosphate ester copolymer (Denka Vinyl # 1000P, manufactured by Denki Kagaku Kogyo Co., Ltd.)
A solution composed of 45 parts of methyl ethyl ketone and 45 parts of toluene was applied and dried by heating to provide an adhesive layer having a thickness of about 0.5 μm.
Next, in a resin solution in which 26 parts of vinyl chloride copolymer (manufactured by Nippon Zeon Co., Ltd., M110) was dissolved in 210 parts of methyl ethyl ketone, linear hydrocarbon-containing compound (A); material of the following structural formula (1) 3 Part

Linear hydrocarbon-containing compound (B): 7 parts of docosyl behenate (Miyoshi Oil & Fats Co., Ltd. prototype) were added, ceramic beads having a diameter of 2 mm were put in a glass bottle, and a paint shaker (manufactured by Asada Tekko Co., Ltd.) was used. Dispersion was carried out over time to create a uniform dispersion. A recording layer solution is prepared by adding 4 parts of an isocyanate compound (manufactured by Nippon Polyurethane Co., Ltd., Coronate 2298-90T) to the dispersion, and after heating and drying on the adhesive layer of the PET film having the light reflection layer, the temperature is 65 ° C. for 24 hours. A recording layer having a thickness of about 10 μm was provided by heating. On this recording layer,
10 parts of 75% butyl acetate solution of urethane acrylate UV curable resin (Dainippon Ink & Chemicals, Unidic C7-157)
A solution consisting of 10 parts of isopropyl alcohol and 3 parts of calcium carbonate was applied with a wire bar, dried by heating, and then crosslinked with an 80 w / cm ultraviolet lamp to form a protective layer film having a thickness of about 3 μm.

Adhesive layer-Adjustment of adhesive layer solution-
1) Saturated polyester resin (solid content 30%, toluene / MEK = 8/2: Tg = 5.5 ° C.)
25 parts 2) saturated polyester resin (solid content 30%, toluene / MEK = 8/2: Tg = 65 ° C.)
5 parts 3) HDI isocyanate cross-linking agent (M-Takeda Chemical Co., Ltd., D-170N) 1 part 4) Toluene 56 parts 5) Methyl ethyl ketone 14 parts 6) Polyhydric alcohol fatty acid ester (RIKEN Vitamin Co., SL-02) 0 6 parts 7) Cross-linked spherical acrylic monodispersed particles (particle size 15 μm, particle size distribution 13.5 to 16.5 μm) 0.5 parts The above composition was added and stirred well to prepare an adhesive layer coating solution.
The adhesive layer coating solution was applied to the opposite surface of the recording layer and protective layer coated film with a wire bar, dried by heating at 100 ° C. for 2 minutes, and then heated at 50 ° C. for 48 hours to form a coating film having a thickness of about 10 μm.

(Comparative Example 1)
Except for the formation of the adhesive layer, the same as Example 1.
Adhesive layer-Adjustment of adhesive layer solution-
1) Saturated polyester resin (solid content 30%, toluene / MEK = 8/2: Tg = 5.5 ° C.)
30 parts 2) Toluene 56 parts 3) Methyl ethyl ketone 14 parts 4) Polyhydric alcohol fatty acid ester (SL-02 manufactured by Riken Vitamin Co., Ltd.) 0.6 parts The above composition was added and stirred well to prepare an adhesive layer coating solution. .
An adhesive layer coating solution is applied to the opposite side of the recording layer, intermediate layer, and protective layer coated film with a wire bar, heated and dried at 100 ° C. for 2 minutes, and then heated at 50 ° C. for 48 hours to form a coated film having a thickness of about 10 μm. Created.

(Comparative Example 2)
Except for the formation of the adhesive layer, the same as Example 1.
Adhesive layer-Adjustment of adhesive layer solution-
1) Saturated polyester resin (solid content 30%, toluene / MEK = 8/2: Tg = 65 ° C.)
30 parts 2) Toluene 56 parts 3) Methyl ethyl ketone 14 parts 4) Polyhydric alcohol fatty acid ester (manufactured by Riken Vitamin Co., SL-02) 0.6 parts The above composition was added and stirred well to prepare an adhesive layer coating solution. .
An adhesive layer coating solution is applied to the opposite side of the recording layer, intermediate layer, and protective layer coated film with a wire bar, heated and dried at 100 ° C. for 2 minutes, and then heated at 50 ° C. for 48 hours to form a coated film having a thickness of about 10 μm. Created.

(Comparative Example 3)
Except for the formation of the adhesive layer, the same as Example 1.
Adhesive layer-Adjustment of adhesive layer solution-
1) Saturated polyester resin (solid content 30%, toluene / MEK = 8/2: Tg = 5.5 ° C.)
30 parts 2) HDI-based isocyanate crosslinking agent (solid content 75%) 0.9 part 4) Toluene 56 parts 5) Methyl ethyl ketone 14 parts 6) Polyhydric alcohol fatty acid ester (manufactured by Riken Vitamin Co., Ltd., SL-02) 0.6 parts 7) Silicon particles (TOSPARAL 3120 manufactured by Toshiba Silicone Co., Ltd., particle size 12μm, particle size distribution 8-23μm)
0.9 parts The above composition was added and stirred well to prepare an adhesive layer coating solution.
An adhesive layer coating solution is applied to the opposite side of the recording layer, intermediate layer, and protective layer coated film with a wire bar, heated and dried at 100 ° C. for 2 minutes, and then heated at 50 ° C. for 48 hours to form a coated film having a thickness of about 10 μm. Created.

(Comparative Example 4)
Except for the formation of the adhesive layer, the same as Example 1.
Adhesive layer-Adjustment of adhesive layer solution-
1) Saturated polyester resin (solid content 30%, toluene / MEK = 8/2: Tg = 5.5 ° C.)
30 parts 2) HDI isocyanate crosslinking agent (solid content 75%) 0.9 part 3) Toluene 56 parts 4) Methyl ethyl ketone 14 parts 5) Polyhydric alcohol fatty acid ester (manufactured by Riken Vitamin Co., Ltd., SL-02) 0.6 parts 6) Silicon particles (Tospearl 145 manufactured by Toshiba Silicone Co., Ltd., particle size 4.5 μm) 0.3 part The above composition was added and stirred well to prepare an adhesive layer coating solution.
An adhesive layer coating solution is applied to the opposite side of the recording layer, intermediate layer, and protective layer coated film with a wire bar, heated and dried at 100 ° C. for 2 minutes, and then heated at 50 ° C. for 48 hours to form a coated film having a thickness of about 10 μm. Created.

A sample in which two core sheets made of white vinyl chloride are sandwiched between two reversible thermosensitive recording media prepared above and two oversheets made of transparent vinyl chloride, pressure 15 kg / cm ² , temperature 130 ° C., time A reversible thermosensitive recording medium containing a vinyl chloride sheet was prepared by laminating in 20 minutes.
Further, a sample in which two core sheets made of white amorphous copolyester were sandwiched between two sheets of reversible thermosensitive recording medium and transparent amorphous copolyester was pressed at a pressure of 15 kg / cm ² , temperature Lamination was carried out at 110 ° C. for 20 minutes to prepare a reversible thermosensitive recording medium containing an amorphous copolyester.
Furthermore, a vinyl chloride sheet is laminated, and a reversible thermosensitive recording medium is laminated on a substrate whose surface is treated with an acrylic resin at a pressure of 15 kg / cm ² , a temperature of 130 ° C., and a time of 20 minutes. A reversible thermosensitive recording medium including a sheet was prepared.
The sample prepared by laminating was processed into a card size.

Evaluation 1 (Repeatability in low temperature environment (5 ° C))
The card created above and the card reader / writer R28000 (manufactured by Kyushu Matsushita Co., Ltd.) are placed in a constant temperature and humidity chamber in a 5 ° C. environment, and after sufficient temperature control, the printing energy is set to 0.75 mJ / dot and the erasing temperature is set to 136 ° C. Then, erasing and printing were repeated 100 times.
The evaluation results were judged as follows.
○: Repeated erasure printing was performed, but the card was not peeled off, and both the printed part and the erased part could be clearly determined.
Δ: When repeated erasure printing is performed, a defective portion due to peeling is observed in a part of the printing portion and the erasing portion.
X: When repeated erasure printing is performed, peeling occurs from the card edge portion, and it cannot be used 100 times repeatedly.

Evaluation 2 (Adhesive strength in low temperature environment (5 ° C))
A thin film-like reversible thermosensitive recording medium prepared in Examples and Comparative Examples was cut into a 10 mm wide tape, and the vinyl chloride sheet (M1063, manufactured by Taihei Chemical Co., Ltd.) used for the above bonding was used. After bonding to a polyester sheet (Mitsubishi Resin Co., Ltd .: PG-CHI) and acrylic (acrylic-treated vinyl chloride sheet) at 20 kg / cm ² at 120 ° C. for 1 minute using a laminate tester (Unique). Then, put it together with a tensile tester (tester industry) in a constant temperature and humidity chamber of 5 ° C. environment and adjust the temperature sufficiently. Then, 180 degree peeling was performed at a peeling speed of 300 mm / min. Similarly, the measurement was performed in a normal temperature environment (22 ° C.).
The adhesive strength at that time was judged as follows.
○: Adhesive strength is 500 g / cm or more or sufficient adhesive strength to break the substrate.
Δ: Adhesive strength is 250 g / cm or more.
X: Adhesive strength is less than 250 g / cm.

Evaluation 3 (Evaluation of blocking resistance with the medium surface)
The recording layer surface side of the reversible thermosensitive recording medium prepared above and the adhesive layer were overlapped, held in a 50 ° C. environment with a load of 3 kg / cm ² for 24 hours, then taken out and peeled off.
The blocking resistance at that time was judged as follows.
A: There is no sticking between the surface layer and the adhesive layer.
◯: There is no problem although the surface layer and the adhesive layer have some sticking.
Δ: Strong adhesion between the surface layer and the adhesive layer.
X: The surface layer sticks to the adhesive layer and peels off.

Evaluation 4 (dispersed state in adhesive coating solution)
The aggregation state (filterability) of the adhesive layer coating liquid used in each Example and Comparative Example and the roughness of the adhesive layer surface of the prepared reversible thermosensitive recording medium were visually observed.
○: There is no filter clogging or agglomerate during filtration, and the adhesive layer coating surface is tentacles and there is no roughness.
Δ: There is a tendency that the filter is slightly clogged during filtration, but there is little roughness on the coated surface of the adhesive layer.
X: A large amount of aggregates are present in the filtration filter, and the adhesive layer coating surface is also rough.
The evaluation results are shown in Table 1 below.

  From Table 1, according to the present invention, peeling occurs even when a durability test in which erasing and printing are repeated on each bonded base material of vinyl chloride, amorphous copolyester, and acrylic surface layer in a low temperature environment. Good printing and erasing can be repeated. Further, it is possible to achieve both the durability against repetition and the blocking resistance between the surface layer on the recording layer side of the reversible thermosensitive recording medium and the adhesive layer. Furthermore, since the dispersion state in the adhesive coating solution is also good, it can be seen that the coating property is also excellent.

  According to the present invention, even in a low temperature environment, the adhesive layer has a high adhesive force with respect to diversifying substrates for bonding such as PVC, PET-G, and acrylic, has repeated durability, and has a recording medium surface layer. There are provided a reversible thermosensitive recording medium having a non-blocking adhesive layer, a member having an information storage unit using the reversible thermosensitive recording medium, an image processing method, and an image processing apparatus.

It is a figure which shows an example of the thermocompression bonding process of the reversible thermosensitive recording medium and base material sheet in this invention. It is a figure which shows another example of the thermocompression-bonding process of the reversible thermosensitive recording medium and base material sheet in this invention. It is a figure which shows the color development and decoloring characteristic of the reversible thermosensitive recording medium of this invention.

Explanation of symbols

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

Claims (18)

  A reversible thermosensitive recording medium having a thermoreversible recording layer whose color tone is reversibly changed by heat on a support and having an adhesive layer on the opposite surface of the support, wherein the adhesive layer contains cross-linked spherical particles A reversible thermosensitive recording medium.   The reversible thermosensitive recording medium according to claim 1, wherein the cross-linked spherical particles are an acrylic resin.   3. The reversible thermosensitive recording medium according to claim 1, wherein the particle size distribution of the crosslinked spherical particles is a particle size distribution in which the particles are aggregated within a range of ± 10% with respect to the average particle size.   The reversible thermosensitive recording medium according to any one of claims 1 to 3, wherein the particle diameter of the crosslinked spherical particles is larger than the thickness of the adhesive layer.   The reversible thermosensitive recording medium according to any one of claims 1 to 4, wherein the cross-linked spherical particles have an average particle diameter of 5 to 20 µm.   6. The reversible thermosensitive recording medium according to claim 1, wherein the adhesive layer contains at least two kinds of resins having a difference in glass transition point (Tg) and a crosslinking agent having an isocyanate group. .   The reversible thermosensitive recording medium according to claim 6, wherein the difference in glass transition point (Tg) between the two kinds of resins contained in the adhesive layer is 30 ° C. or more.   The two types of resins contained in the adhesive layer are a resin having a glass transition point (Tg) of -30 to 10 ° C and a resin having a glass transition point (Tg) of 30 to 80 ° C. Item 7. The reversible thermosensitive recording medium according to Item 6.   The two types of resins contained in the adhesive layer, the ratio of the resin having a glass transition point (Tg) of -30 to 10 ° C is 50 to 95% by mass. Sexual thermal recording medium.   The reversible thermosensitive recording medium according to any one of claims 1 to 9, wherein the crosslinked spherical particles are contained in a proportion of 5 to 30% by mass with respect to the resin contained in the adhesive layer.   A member having an information storage unit, comprising: an information storage unit and a reversible display unit, wherein the reversible display unit includes at least the thermoreversible thermosensitive recording medium according to claim 1.   The member according to claim 11, wherein the member having the information storage unit is a card, a disk, a disk cartridge, or a tape cassette.   The reversible thermosensitive recording medium according to any one of claims 1 to 10 or the thermoreversible recording layer of the member having the information storage unit according to claim 11 or 12 is heated to form an image and / or An image processing method comprising performing erasing.   The image processing method according to claim 13, wherein an image is formed using a thermal head.   The image processing method according to claim 13, wherein the image is erased using a thermal head or a ceramic heater.   A reversible thermosensitive recording medium according to any one of claims 1 to 10, or a member having the information storage section according to claim 11 or 12, and means for forming and / or erasing an image. An image processing apparatus characterized by comprising:   The image processing apparatus according to claim 16, wherein the image forming unit is a thermal head. The image processing apparatus according to claim 16, wherein the image erasing means is a thermal head or a ceramic heater.

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