JP2000043429A - Reversible thermosensitive recording medium, and method and apparatus for recording and erasing image using the medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reversible thermosensitive recording medium having excellent printing characteristics by a thermal head with small deformation such as a curl or the like even in the case of repeatedly printing or erasing via an erasing bar using an initial and thermal head, a hot stamp or a ceramic heater in a thick card like a general purpose JIS standard card. SOLUTION: In the reversible thermosensitive recording medium comprising a thermosensitive layer containing at least a resin and reversibly changing in a transparency depending upon a temperature on a support 2; the support 2 is formed by sequentially laminating a first sheet, a second sheet and a third sheet so that its total thickness is 600 to 1,000 μm, and a deformation is 0.5 mm or less after the first and third sheets are dipped in a dimethyl silicone oil heated to 80 deg.C for 5 min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible thermosensitive recording material, and more particularly to a method for repeatedly writing and erasing information by mainly utilizing a reversible transparency or color tone change depending on the temperature of a thermosensitive layer (recording layer). The present invention relates to a reversible thermosensitive recording medium that can be used and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in a prepaid card of a reduced amount type such as various kinds of PVC cards, PET cards, paper cards, synthetic paper cards, etc., even if there is a large amount of money which cannot be used many times, there is a remaining amount. However, because the print area is exhausted and cannot be used, or it is difficult to print small characters or the like, the update record such as the balance is not adopted. Therefore,
The remaining balance or the frequency is generally notified by drilling or the like. For this reason, there is a problem that the use history, the accurate balance, and the like cannot be known.

On the other hand, recently, a card having a reversible thermosensitive recording layer in which a transparent state and a cloudy state are reversibly changed depending on temperature on one side of the card has been proposed. However, conventionally, a medium such as a card having a reversible thermosensitive recording layer of this type has a thickness of 188 μm such as a prepaid card, and is thinner than a credit card conforming to JIS standard X6301 or the like, and is difficult to handle as a card. There were problems such as curling easily due to repetition of printing and erasing. In order to solve these drawbacks, Japanese Patent Application Laid-Open No. 05-169808 discloses a configuration in which a support has a multi-layer sheet bonded thereto.
And JP-A-07-266716.

Japanese Patent Application Laid-Open No. 05-2005 discloses an arrangement in which an adhesive layer is provided on the side of a medium sheet having a reversible thermosensitive recording layer opposite to the recording layer surface for the purpose of displaying on a card medium, and the medium sheet is attached to the card medium. No. 262033, JP-A-06-115244, JP-A-07-001840
JP-A-08-099468, JP-A-09-09468
No. 0666680. However, in Japanese Patent Application Laid-Open No. 05-169808,
When a configuration is adopted in which a T sheet and a PET sheet are bonded,
The thickness of the general-purpose PET film is up to 350 μm, and the general-purpose white light-shielding type general-purpose product for a card has a thickness of only 250 μm. It has a thickness of just over 6 mm, and does not have a thickness of 0.68 to 0.8 mm according to JIS6301 standard and a thickness of 0.68 to 0.84 mm according to ISO 2894 standard. A sheet having a thickness of 188 μm for a prepaid card having a conventional reversible thermosensitive recording layer;
When a 250 μm thick sheet of white light-shielding type is bonded in-line and made into a card, even in the initial state after processing into a card shape, curl that is considered to be caused by winding of a roll occurs and as a solution to the problem Was not enough.

[0005] The conventional method of producing a thick card from a PVC card process as in the technique described in JP-A-07-266716 substantially eliminates the above-mentioned problems. However, in the case of repeatedly recording and erasing with a hot stamp erasing device in the repeated recording of a card having a reversible thermosensitive recording layer created because the support itself is a PVC sheet, the erasing temperature of these media In most cases, the temperature is set to a high temperature of 80 to 100 ° C. or higher, so that the card is deformed by heat.

Further, Japanese Patent Application Laid-Open No. 05-262033,
JP-A-06-115244, JP-A-07-001
JP-A-840, JP-A-08-099468, and JP-A-09-066680, in a configuration in which a label-like reversible thermosensitive recording medium having an adhesive layer is attached, a cushion layer, a heat insulating layer, or the like is used. In addition to the necessity of providing a layer having a function of absorbing irregularities and undulations of the card to be worn, it requires another unconvenient step of bonding to the card body.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks and is intended to reduce the erasure of printing on an erase bar using an initial and thermal head and a hot stamp or a ceramic heater in a thick card such as a general-purpose JIS standard card. It is an object of the present invention to provide a reversible thermosensitive recording medium which has less deformation such as curling even when repeated, and has excellent printing characteristics with a thermal head.

[0008]

Means for Solving the Problems The object of the present invention is to provide (1) a reversible thermosensitive recording medium comprising at least a resin on a support and a thermosensitive layer whose transparency reversibly changes depending on temperature. , The support is laminated in the order of a first sheet, a second sheet, and a third sheet, and the total thickness is 600 μm.
m and 1000 μm or less, wherein the first and third sheets have a deformation of 0.5 mm or less after being immersed in dimethyl silicone oil heated to 80 ° C. for 5 minutes ”. (2) a reversible thermosensitive recording medium having at least a resin and a thermosensitive layer whose transparency reversibly changes depending on temperature on a support,
The support is formed by laminating three layers of sheets via an adhesive layer, the total thickness of which is not less than 600 μm and not more than 1000 μm, and each sheet to be bonded is immersed in dimethyl silicone oil heated to 80 ° C. for 5 minutes. 0.5m deformation
m or less, a reversible thermosensitive recording medium,
(3) “The reversible thermosensitive recording medium according to the above (1) or (2), wherein a magnetic recording layer is provided on any part of the support”, (4) “ (5) The method for recording and erasing an image on a reversible thermosensitive recording medium for recording and erasing an image by heating using the reversible thermosensitive recording medium according to the above (1) to (3); An image recording and erasing apparatus for a reversible thermosensitive recording medium, comprising: a heating means for heating and forming an image by heating the reversible thermosensitive recording medium according to the items (1) to (3); Achieved.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, there is provided a reversible thermosensitive recording medium comprising at least a resin on a support and a thermosensitive layer whose transparency reversibly changes depending on temperature. Are laminated in the order of a first sheet, a second sheet, and a third sheet, and the total thickness thereof is 600 μm or more and 1
000 μm or less, and the adhesive strength is JIS K-6.
When represented by the average value of the tensile load measured according to 854180 degree peeling, it is 0.8 kgf / 15 mm or more, and the film sheet serving as a base of the first sheet and the third sheet has a viscosity of 1 to 5 × at 25 ° C. 10 ^-4 m / s
Is less than 0.5 mm after immersion in a heat transfer medium heated to 80 ° C. for 5 minutes (the support is formed by laminating a three-layer sheet via an adhesive layer, and Is 600 μm or more and 1000 μm or less, and its adhesive strength is 0.8 when represented by the average value of tensile loads measured according to JIS K-6854 180-degree peeling.
kgf / 15 mm or more, and the film sheet as a base of each sheet has a viscosity of 1-5 × at 25 ° C.
Deformation after immersing 10 ^-4 m / s dimethyl silicone oil in a heat transfer medium heated to 80 ° C. for 5 minutes is 0.5 m
m or less).

In the conventional inline lamination of a sheet of a reversible thermosensitive recording medium having a heat-sensitive layer formed on a 188 μm-thick PET sheet and a 250 μm-thick white light-shielding type sheet, the roll is formed in the initial state after being processed into a card shape. It is not clear why the curl caused by winding and the curl increased by repeated printing and erasure is improved by the three-layer sheet bonding of the present invention. Rigidity against stress caused by shrinkage due to the cross-linking reaction of the layers, bonding of three layers, curling by the cross-linking reaction of each adhesive layer with the upper and lower sheets with respect to the central sheet It is possible that the stress is balanced. In addition, since the thermal deformation temperature of the base films of the first and third sheets to be bonded is 80 ° C. or higher, there is no possibility of thermal deformation due to repeated erasure in a hot stamping device.

The reversible thermosensitive recording medium in the present invention is:
It is a material that reversibly causes a visible change due to a temperature change. Visible changes can be divided into color changes and shape changes, and the present invention mainly uses materials that cause color changes. Changes in color tone include changes in transmittance, reflectance, absorption wavelength, degree of confusion, and the like, and an actual reversible thermosensitive recording medium performs display by combining these changes. More specifically, at present, the system can be classified into two types: (a) a recording medium in which a transparent state and a cloudy state are reversibly changed, and (b) a material recording medium in which a color such as a dye is reversibly changed. (B) As described in the section on conventional technology,
Typical examples are those in which organic low-molecular substances such as higher alcohols and higher fatty acids are dispersed in a resin base material such as polyester, an auxiliary agent is added as necessary, and then the resin base material is crosslinked to provide a recording layer. And (b) cross-linking the binder resin together with enhancing the reversibility of conventional leuco-based thermosensitive recording materials (eg, Yoshihiro Hino, Nie Watanabe, Japan Hardcopy '90, P147). is there. The following (a)
The present invention will be described mainly with respect to the recording medium, but the present invention mainly relates to a support and is not limited to (a).

[0012] Here, the mechanism of the white turbid transparent change of the reversible thermosensitive recording material is presumed as follows. That is, in the case of (I) transparent, the particles of the organic low-molecular substance dispersed in the resin base material are in close contact with the organic low-molecular substance and the resin base material without any gap, and there is no void in the particle part, Light incident from one side is transmitted to the other side without being scattered, so that it looks transparent. (II) In the case of cloudiness, the particles of the organic low-molecular substance are composed of fine crystals of the organic low-molecular substance. There is a gap at the interface of the crystal or the interface between the particle and the resin base material, and the light incident from one side is refracted at the interface between the gap and the crystal, the interface between the gap and the resin, and is scattered. .

In FIG. 1 (representing a change in transparency due to heat), a heat-sensitive layer mainly composed of a resin base material and an organic low-molecular substance dispersed in the resin base material is, for example, T _0.
It is cloudy and opaque at the following room temperature.

As this is heated, it becomes gradually transparent from the temperature T ₁ , becomes transparent when it is _first heated to a temperature T _{2 to} T ₃ , and remains transparent even when it is returned to a normal temperature of T ₀ or less in this state. is there. It begins to resin softening from around the temperature T _1,
As the softening progresses, the resin shrinks to reduce the interface between the resin and the organic low-molecular substance particles or the voids in the particles,
The transparency gradually increases, and at a temperature T _{2 to} T ₃ , the organic low-molecular substance is in a semi-molten state, becomes transparent by filling the remaining gap with the molten organic low-molecular substance, and is cooled while the seed crystal remains. It is considered that the crystallization occurs at a relatively high temperature, and the resin is still in a softened state, so that the resin follows the change in the volume of the particles accompanying the crystallization, and no void is formed, so that the transparent state is maintained.

Further heating to a temperature equal to or higher than T ₄ results in a translucent state intermediate between the maximum transparency and the maximum opacity. Next, when the temperature is lowered, the state returns to the original cloudy and opaque state without taking the transparent state again. After this the organic low molecular weight substance at a temperature T ₄ or more completely melted, crystallized little higher temperature than T ₀ becomes supercooled state, this time, can not follow the volume change of the resin is caused by the crystallization, voids It seems to happen. However, the temperature-transparency change curve shown in FIG. 1 is only a typical example, and changing the material causes a change in the transparency and the like in each state according to the material.

The reversible thermosensitive recording material of the present invention utilizes the change in transparency (transparent state, cloudy opaque state) as described above. Therefore, by selectively applying heat, the heat-sensitive layer can be selectively heated to form a cloudy image on a transparent ground, and a transparent image on a cloudy ground, and the change can be repeated many times. . If a colored sheet is arranged on the back side of such a heat-sensitive layer, an image of the color of the colored sheet on a white background or an image of a white background on the colored background of the colored sheet can be formed. Further, when projected by an OHP (overhead projector) or the like, the cloudy portion becomes a dark portion, the transparent portion transmits light, and becomes a bright portion on the screen.

The resin base material used for the heat-sensitive layer is a material that forms a layer in which organic low-molecular substances are uniformly dispersed and held, and that affects the transparency at the time of maximum transparency. Therefore, the resin base material is preferably a resin having good transparency, mechanical stability, and good film-forming property. Such resins include polyvinyl chloride; vinyl chloride-vinyl acetate copolymer, vinyl chloride-
Vinyl acetate-vinyl alcohol copolymer, vinyl chloride-
Vinyl chloride copolymers such as vinyl acetate-maleic acid copolymer and vinyl chloride-acrylate copolymer; vinylidene chloride copolymers such as polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer Copolymer; polyester; polyamide; polyacrylate or polymethacrylate or acrylate-
Methacrylate copolymer; silicone resin and the like. Of course, these resins may be used alone or in combination of two or more.

It is preferable to crosslink these resins.
The repeated durability of the crosslinked medium is improved. In the case of crosslinking, the resin preferably has a functional group such as a hydroxy group, a carboxy group, or an epoxy group. As a method of crosslinking, there is a method by thermal crosslinking, irradiation of UV or EB,
It is preferable to perform crosslinking by adding an isocyanate or various acrylic crosslinking agents. Glass transition temperature of resin matrix is 70 ° C
Or more, more preferably 80 ° C. or more, and 90 ° C.
The above is particularly preferred. As the glass transition temperature increases, the image heat resistance further improves.

The thickness of the heat-sensitive layer of the thermoreversible recording medium of the present invention is preferably from 1 to 30 μm, more preferably from 2 to 20 μm. Particularly preferred is 4 to 15 μm. If the recording layer is too thick, heat distribution within the layer will occur, making it difficult to achieve uniform transparency. On the other hand, if the heat-sensitive layer is too thin, the turbidity decreases and the contrast decreases. The turbidity can be increased by increasing the amount of the fatty acid in the recording layer. The ratio between the organic low-molecular substance and the resin (the resin having a crosslinked structure) in the heat-sensitive layer is preferably about 2: 1 to 1:16 by weight,
1: 2 to 1: 8 is more preferable, 1: 2 to 1: 5 is particularly preferable, 1: 2 to 1: 4 is more preferable, and 1: 2 to 1: 2 is more preferable.
1: 3 is more preferred. When the ratio of the resin is less than this, it becomes difficult to form the organic low-molecular substance in the film held in the resin, and when the ratio is more than this, the amount of the organic low-molecular substance is small, so that it is difficult to make opaque. .

To make the reversible thermosensitive recording material of the present invention,
First, a heat-sensitive layer is formed on a support by, for example, the following method. In some cases, it can be formed as a sheet without using a support. 1) Dissolve the resin base material and the organic low-molecular substance in a solvent, apply this on a support, evaporate the solvent to form a film or sheet, and crosslink, or crosslink after forming the sheet. Method. 2) Dissolve the resin matrix in a solvent that dissolves only the resin matrix, pulverize or disperse the organic low-molecular substance therein by various methods, apply this on a support, and evaporate the solvent to form a film or A method in which a sheet is formed and crosslinked, or a sheet is formed and then crosslinked. 3) A method in which a resin base material and an organic low-molecular substance are heated and melt-mixed without using a solvent, formed into a film or sheet, cooled, and then crosslinked.

The solvent for forming the heat-sensitive layer or the heat-sensitive recording material can be variously selected depending on the types of the resin base material and the organic low-molecular substance. Examples thereof include tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, chloroform, carbon tetrachloride, ethanol, toluene, and the like. Benzene and the like can be mentioned. In addition, of course, when a dispersion is used,
Even when a solution is used, in the heat-sensitive layer obtained, the organic low-molecular substance is precipitated as fine particles and exists in a dispersed state.

The organic low-molecular substance dispersed in the resin base material may be any substance that becomes particulate in the recording layer, and generally has a melting point of 30 to 200 ° C., preferably about 50 to 150 ° C. Is done. Such organic low molecular weight substances include alkanol; alkane diol; halogen alkanol or halogen alkane diol; alkylamine; alkane; alkene; alkyne; halogen alkane; halogen alkene; halogen alkyne; cycloalkane; cycloalkene; Unsaturated mono- or dicarboxylic acids or their esters, amides or ammonium salts; saturated or unsaturated halogen fatty acids or their esters, amides or ammonium salts; allylcarboxylic acids or their esters, amides or ammonium salts; Ester, amide or ammonium salt thereof; thioalcohol; thiocarboxylic acid or ester, amine or ammonium salt thereof; carboxylic acid ester of thioalcohol Etc. The. These may be used alone or in combination of two or more. These compounds have 10 to 60 carbon atoms, preferably 10 to 38 carbon atoms, particularly preferably 10 to 30 carbon atoms. The alcohol group in the ester may be saturated, may not be saturated, and may be halogen-substituted. In any case, the organic low molecular weight substance contains at least one of oxygen, nitrogen, sulfur and halogen in the molecule, for example, -OH, -C
_{OOH, -CONH 2, -COOR, -NH} -, - NH
It is preferably a compound containing ₂ , -S-, -SS-, -O-, halogen and the like.

In the present invention, as the organic low-molecular substance, a transparent melting temperature range can be further expanded by using a combination of a low-melting organic low-molecular substance and a high-melting organic low-molecular substance. Is preferred. The difference between the melting points of the low-melting point organic low-molecular substance and the high-melting point organic low-molecular substance is preferably 20 ° C or higher, more preferably 30 ° C or higher, and particularly preferably 40 ° C or higher.

The low melting point organic low molecular weight material preferably has a melting point of 40 ° C. to 100 ° C., and more preferably 50 ° C. to 80 ° C. As high-melting organic low-molecular substances,
Those having a melting point of 100 ° C to 200 ° C are preferred, and those having a melting point of 110 ° C to
Those at 180 ° C. are more preferred.

Next, examples of the high-melting organic low-molecular substance used in the present invention include aliphatic saturated dicarboxylic acids, ketones having higher alkyl groups, semicarbazones derived from the ketones, α-phosphono fatty acids, and the like. The following are preferred, but not limited thereto. These may be used alone or in combination of two or more.

Specific examples of these low-molecular organic substances having a melting point of 100 ° C. or higher are shown below. Specific examples of the aliphatic dicarboxylic acid having, for example, a melting point of about 100 to 135 ° C. include, for example,
Succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid,
Dodecandioic acid, tetradecandioic acid, pentadecandioic acid,
Hexadecandioic acid, heptadecandioic acid, octadecandioic acid, nonadecandioic acid, eicosandioic acid, heneicosandioic acid, docosandioic acid, and the like.

The ketone used in the present invention contains a ketone group and a higher alkyl group as essential constituent groups, and may also contain an unsubstituted or substituted aromatic ring or a substituted ring. The total carbon number of the ketone is preferably 16 or more, more preferably 21 or more. The semicarbazone used in the present invention is derived from the above ketone.

The ketone and semicarbazone used in the present invention include, for example, the following. 3-octadecanone, 7-eicosanone,
14-heptacosanone, 18-pentatriacontanone, tetradecanophenone, docosanophenone, docosanonaphthophenone, 2-heneicosanone semicarbazone.

The α-phosphono fatty acid used in the present invention is, for example, E. coli. V. Kaurer et al. Ak. Oil Che
According to the method of mist's Soc.
α-brominated acid bromide by bromination by an inskin reaction, and then ethanol is added to obtain α-bromo fatty acid ester. Can be obtained by recrystallization from toluene.

Specific examples of the phosphono fatty acid used in the present invention are shown below. α-phosphonomyristylic acid, α-phosphonopalmitic acid, α-phosphonostearic acid and the like. In addition, except for α-phosphonoberalgonic acid, two m
p (melting point).

The mixing weight ratio of the low-melting organic low-molecular substance and the high-melting organic low-molecular substance is preferably from 95: 5 to 5:95, more preferably from 90:10 to 10:90, and more preferably from 80:10 to 10:90.
20-20: 80 is particularly preferred. Further, in addition to these low melting point organic low molecular weight substances and high melting point organic low molecular weight substances, other organic low molecular weight substances described above may be mixed and used. These include the following.

These compounds include lauric acid, dodecanoic acid, myristic acid, pentadecanoic acid, palmitic acid,
Stearic acid, behenic acid, nonadecanoic acid, arginic acid,
Higher fatty acids such as oleic _{acid; C 16 H 33 -O-C} 16 H 33, C 16 H 33 -S-C 16 H 33, C 18 H 37 -S-C 18 H 37, C 12 H 25 -S- _{C 12 H 25, C 19 H} 39 -S-C 19 H 39, C 12 H 25 -S-S-C 12 H 25,

[0033]

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[0034]

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[0035]

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[0036]

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[0037]

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[0038]

Embedded image And ether or thioether. In particular, the present invention
In higher fatty acids, especially palmitic acid, pentadecanoic acid,
Nonadecanoic acid, arachiic acid, stearic acid, behenic acid,
Higher fatty acids having 16 or more carbon atoms such as lignoceric acid are preferred.
Higher fatty acids having 16 to 24 carbon atoms are more preferable.

As described above, in the present invention, in order to widen the range of the temperature at which transparency can be achieved, the organic low-molecular substances described in this specification are appropriately combined, or another organic low-molecular substance having a melting point different from that of the organic low-molecular substances is used. What is necessary is just to combine with a material. These are described, for example, in JP-A-63-39378.
JP-A-63-130380, JP-A-4-2350
No. 95, but are not limited thereto.

The ratio between the organic low-molecular substance and the resin (resin having a crosslinked structure) in the heat-sensitive layer was 2: 1 by weight.
About 1:16 is preferable, and 1: 2 to 1: 8 is more preferable. When the ratio of the resin is less than this, it becomes difficult to form the organic low-molecular substance in the film held in the resin, and when the ratio is more than this, the amount of the organic low-molecular substance is small, so that it is difficult to make opaque. .

In addition to the above components, additives such as a surfactant and a plasticizer can be added to the heat-sensitive layer in order to facilitate formation of a transparent image. Specific examples of these additives are as follows.

Examples of the plasticizer include phosphoric acid esters, fatty acid esters, phthalic acid esters, dibasic acid esters, glycols, polyester plasticizers, and epoxy plasticizers. Specific examples include the following. Tributyl phosphate, tri-2-ethylhexyl phosphate, triphenyl phosphate, tricresyl phosphate, butyl oleate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, di-n-octyl phthalate, phthalate Di-2-ethylhexyl acid, diisononyl phthalate, dioctyldecyl phthalate, diisodecyl phthalate, butylbenzyl phthalate, dibutyl adipate,
Di-n-hexyl adipate, di-2-ethylhexyl adipate, di-2-ethylhexyl azelate, dibutyl sebacate, di-2-ethylhexyl sebacate, diethylene glycol dibenzoate, triethylene glycol di-2-ethyl butyrate , Methyl acetyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, tributyl acetyl citrate and the like.

Examples of surfactants and other additives: polyhydric alcohol higher fatty acid ester; polyhydric alcohol higher alkyl ether; polyhydric alcohol higher fatty acid ester, higher alcohol, higher alkylphenol, higher fatty acid higher alkylamine, higher fatty acid amide Lower olefin oxide adducts of fats and oils or polypropylene glycol; acetylene glycol; Na, Ca, Ba or Mg salts of higher alkylbenzene sulfonic acids; aromatic carboxylic acids, higher fatty acid sulfonic acids, aromatic sulfonic acids, sulfuric acid monoesters or phosphoric acids Mono- or di-ester Ca,
Ba or Mg salt; low sulfated oil; poly long chain alkyl acrylate; acrylic oligomer; poly long chain alkyl methacrylate; long chain alkyl methacrylate-amine-containing monomer copolymer; styrene-maleic anhydride copolymer; Maleic anhydride copolymer and the like.

In addition to these, if there is an interface between the resin and the organic low-molecular substance particles in the heat-sensitive layer and / or voids different from the refractive index of the resin and the particles in the particles, the image density in the cloudy state is reduced. There is an effect that the contrast is improved. The effect is more remarkable when the size of the gap is 1/10 or more of the wavelength of the light used for detecting the opaque state.

When an image formed on the reversible thermosensitive recording material of the present invention is used as a reflection image, it is desirable to provide a light reflecting layer on the back surface of the recording layer. In addition, the presence of the reflective layer makes it possible to reduce the thickness of the recording layer and to greatly increase the contrast. Specific examples include vapor deposition of Al, Ni, Sn and the like (described in JP-A-64-14079).

The heat-sensitive layer may be provided with a protective layer for protecting the heat-sensitive layer. Protective layer (thickness 0.1
As materials, silicone rubber, silicone resin (JP-A-63-221087), polysiloxane graft polymer (JP-A-02-16243) can be used.
No. 6) and an ultraviolet curable resin or an electron beam curable resin (JP-A-03-205655). In any case, a solvent is used at the time of coating, and it is preferable that the solvent does not easily dissolve the resin of the recording layer and the organic low-molecular substance.

Solvents that hardly dissolve the resin and the organic low-molecular substance in the heat-sensitive layer include n-hexane, methyl alcohol, ethyl alcohol, and isopropyl alcohol, and alcohol-based solvents are particularly desirable in terms of cost.

The layer structure of the reversible thermosensitive recording material of the present invention may be, as described in Japanese Utility Model Laid-Open No. 2-3876, a thermosensitive recording layer and a magnetic recording layer mainly composed of a magnetic material on a support. And a layer structure in which at least a portion corresponding to the heat-sensitive recording layer immediately below the heat-sensitive recording layer or on the support is colored.

Alternatively, as described in JP-A-3-130188, a layer structure in which a magnetic recording layer is provided on a support, a light reflecting layer is provided thereon, and a heat-sensitive layer is provided thereon. In this case, the magnetic recording layer may be either on the back surface of the support or provided between the support and the heat-sensitive layer, and there is no problem even with these other layer configurations.

In the present invention, a colored layer may be provided between the support and the heat-sensitive layer in order to improve visibility. The colored layer is formed by applying and drying a solution or dispersion containing a colorant and a resin binder as main components on the target surface, or simply attaching a colored sheet. Here, the colorant only needs to be able to recognize the change in transparency and white turbidity of the upper recording layer as a reflection image, and may include red, yellow, blue, dark blue, purple, black,
Dyes and pigments having a color such as brown, ash, orange, and green are used. As the resin binder, various thermoplastic, thermosetting or ultraviolet curable resins are used.

Hereinafter, a specific configuration of the present invention will be described in detail. 2A to 2D show the basic constitution of the reversible thermosensitive recording material of the present invention. The support (2) of the present invention is shown in FIG.
As described above, the films (3), (4), and (5) are laminated via an adhesive layer. Also (b) ~
As shown in (d), between the support (2) and the heat-sensitive layer (1), and between the films (3) and (4) constituting the support (2), a coloring layer or a light reflecting layer (7). May be provided. In this case, the film sheet (3) is a transparent film. (In the case of (c), a transparent film (3) provided with a colored layer or a light reflecting layer is bonded to the film (4), and in the case of (d), a film provided with a colored layer or a light reflecting layer ( (4) and transparent film (3) adhered) FIGS. 3A and 3B show an example in which a magnetic recording layer is formed on the support of the present invention. Even in the case of a thermal recording medium, a light reflecting layer or a colorant layer may be provided on the back surface of the thermal recording layer for the purpose of improving visibility. Although the specific figure shows that the information storage unit is a magnetic recording layer, this information storage unit may be any of barcode information, magnetic recording information, IC, optical memory, magneto-optical memory and the like.

As the film constituting the support of the reversible thermosensitive recording material of the present invention, paper or plastic can be used. Examples of the plastic film include polyethylene film, polyvinyl alcohol film, polyethylene terephthalate film, polycarbonate film, and polystyrene. Film, polyethylene naphthalate film, fluorinated ethylene propylene film,
Aromatic polyamide film, polyarylate film,
Examples include a plastic film such as a polyimide film, an acrylic resin film, an acrylonitrile-styrene resin film, an ABS resin film, and a polysulfone resin film.

The support (2) is formed by laminating three layers of film sheets via an adhesive layer. The material of each film may be the same or different, and the thickness of each film is What is about 100-350 micrometers may be stuck together. Further, the total thickness of the laminated support is 600 to 1
If the thickness is smaller than 2,000 μm, the effect of laminating is not so different from the case of a two-layer film sheet, and the curl caused by the initial roll winding occurs. If the thickness exceeds 1000 μm, the rigidity of the card is too strong. When recording with a thermal head, the contact between the heat-sensitive layer and the thermal head becomes insufficient, so that printing failure is likely to occur.

The erasing temperature of the recorded image of the reversible thermosensitive recording medium of the present invention is set to 80 ° C. or higher. The heat deformation temperature of the sheet is preferably higher than the erasing temperature, and the viscosity at 25 ° C. is 1 to 1.
5 × 10 ⁻⁴ m / s dimethyl silicone oil at 80 ° C.
After immersion for 5 minutes in a heat transfer medium heated to
mm or less.

As the adhesive for forming the adhesive layer in the reversible thermosensitive recording material of the present invention, any conventionally known adhesive can be used, for example, urea resin, melamine resin, phenol resin, epoxy resin, vinyl acetate resin, Vinyl acetate acrylic copolymer resin, EVA resin, acrylic resin, polyvinyl ether resin, vinyl chloride vinyl acetate copolymer resin, polystyrene resin, polyester resin, polyurethane resin, polyamide resin, chlorinated polyolefin resin Any adhesive such as polyvinyl butyral resin, acrylate copolymer, methacrylate copolymer, natural rubber, cyanoacrylate, and silicone resin can be used. Further, if necessary, a filler, an antioxidant and the like can be added. Also,
The thickness of the adhesive layer is preferably about 1 to 20 μm. In order for the laminated films to have a sufficient adhesive strength, the strength is 0.1 μm as an average value of the tensile load measured according to JIS K-6854 180 ° peeling. 8 kgf / 15 mm or more is sufficient.

In the present invention, when used as a thermosensitive recording image display device for displaying an image, there are various types, and a typical one is a reversible thermosensitive recording material for forming and erasing images. A thermosensitive recording image display device or an image forming device in which the image forming means and the image erasing means for performing the image processing can be performed by changing the energy applied to the thermal head with the same heating element such as a thermal head. Is a thermal head, and the image erasing means is a thermal head, a hot stamp,
There is a thermosensitive recording image display device selected from one of a contact pressing type means for adhering a heating element such as a heat roller and a heat block, or a non-contact type means using hot air or infrared rays.

One example of a method and apparatus for recording and erasing an image on the reversible thermosensitive recording medium of the present invention will be described below. For recording an image, an image recording means such as a thermal head or a laser capable of partially heating a medium on the image is used. As mentioned above, erasing images can be done with hot stamping,
Image erasing means such as a ceramic heater, a heat roller, hot air, a thermal head, and a laser are used. Among them, a ceramic heater and a thermal head are preferably used. By using a ceramic heater, the size of the apparatus can be reduced, a stable erased state can be obtained, and an image with good contrast can be obtained. It goes without saying that the upper limit of the set temperature is the erasable temperature upper limit.

Further, by using a thermal head, further miniaturization can be achieved, power consumption can be reduced, and a battery-driven hand-held device can be realized. If a single thermal head is used for both recording and erasing, the size can be further reduced. When performing recording and erasing with one thermal head, a new image may be recorded again after erasing all previous images once, or the previous image may be erased at once by changing the energy for each image, and a new image may be recorded. An overwrite method of recording an image is also possible. In the overwrite method, the time for recording and erasing is reduced, which leads to an increase in recording speed. In the case of using a card having a thermosensitive layer and an information storage unit, the above-described device also includes a unit for reading the storage of the information storage unit and a unit for rewriting the storage.

[0059]

The present invention will be described more specifically with reference to examples and comparative examples. Parts here are by weight. Example 1 A PET film having a thickness of about 188 μm was subjected to aluminum evaporation at 500 °, and 5 parts of behenic acid 5 parts of eicosane diacid 40 parts of vinyl chloride-vinyl acetate copolymer (VYHH manufactured by Union Carbite Co.) 150 parts of THF A solution consisting of 20 parts of toluene was applied and dried by heating to form a heat-sensitive layer having a thickness of about 10 μm, and a urethane acrylate ultraviolet curable resin (Unidick C7-1, manufactured by Dainippon Ink Co., Ltd.) was provided thereon.
57) with a wire bar, and after drying by heating, 80 W /
The film was irradiated with an ultraviolet lamp having a thickness of about 4 cm and cured to provide an overcoat layer having a thickness of about 4 μm, thereby producing a film having a reversible thermosensitive recording layer. On the side opposite to the recording layer side of this film, Toray's Lumirror E-20 (250 μm thick) was used.
m PET film) is bonded in-line using a thermosetting epoxy-based adhesive, and again on the opposite side of the recording layer, the same Toray Lumirror E-20 (250 μm thick)
m), and after aging thermosetting, about 72
A reversible thermosensitive recording medium having a total thickness of 0 μm was obtained. Thereafter, this medium was cut into a card size to produce a card.

Example 2 The procedure of Example 1 was repeated except that the plastic film to be bonded to the film having the reversible thermosensitive recording layer was changed to SRA-BOOB (200 μm ABS resin sheet) manufactured by Tsutsunaka Plastics Industry Co., Ltd. Total thickness about 62
A 0 μm reversible thermosensitive recording medium was obtained, and this medium was cut into a card size to prepare a card.

Example 3 The surface of the film having a reversible heat-sensitive recording layer of Example 1 opposite to the recording layer side and Lumirror E-20 manufactured by Toray Industries (thickness: 2)
A 50 μm PET film) is bonded in-line using a thermosetting epoxy adhesive, and a PET film having a magnetic recording layer (270 μm thick) is bonded and aged by thermosetting. A thermal recording medium was obtained, and this medium was punched into a card size to make a card.

Example 4 In Example 1, a film having a reversible thermosensitive recording layer was heat-curable on a surface opposite to the recording layer side by using Sunroid Vip R-1700 (200 μm thick PVC sheet) manufactured by Tsutsunaka Plastics Industry Co., Ltd. After laminating in-line using an epoxy adhesive, laminating a PET film having a magnetic recording layer (270 μm in thickness) and aging thermosetting, a reversible thermosensitive recording medium having a total thickness of about 700 μm was obtained.
This medium was punched into a card size to make a card.

Comparative Example 1 The surface of the film having a reversible thermosensitive recording layer of Example 1 opposite to the recording layer side and Sunroid Vip R-1700 (500 μm thick PVC sheet) manufactured by Tsutsunaka Plastics Industry Co., Ltd.
Were bonded in-line using a thermosetting epoxy adhesive, and after aging heat curing, a reversible thermosensitive recording medium having a total thickness of about 710 μm was obtained, and this medium was punched into a card size to prepare a card.

Comparative Example 2 A 500 ° aluminum vapor-deposited film was formed on a PET film having a thickness of about 250 μm, a recording layer solution having the same formulation as in Example 1 was applied, dried by heating, and a heat-sensitive layer having a thickness of about 10 μm was provided. Then, an overcoat layer of about 4 μm was provided thereon in the same manner as in Example 1 to form a film having a reversible thermosensitive recording layer.
Then, a surface of the film opposite to the recording layer side and Lumirror S (a 350 μm thick PET film) manufactured by Toray Industries, Inc. are bonded in-line using a thermosetting epoxy-based adhesive. A reversible thermosensitive recording medium having a total thickness was obtained, and this medium was punched into a card size to prepare a card.

Comparative Example 3 A PET film (thickness: 270 μm) having a magnetic recording layer and a surface opposite to the recording layer side of the film having a reversible thermosensitive recording layer of Example 1 were adhered to each other. Obtaining a reversible thermosensitive recording medium having a total thickness of about 480 μm,
This medium was punched into a card size to make a card.

Comparative Example 4 Comparative Example 1 was repeated except that the film to be bonded to the film having the reversible thermosensitive recording layer was changed to Sunroid Vip R-1700 (800 μm thick PVC sheet) manufactured by Tsutsunaka Plastics Industry Co., Ltd. Total thickness 10
A reversible thermosensitive recording medium of 10 μ was obtained, and this medium was cut into a card size to prepare a card.

COMPARATIVE EXAMPLE 5 In Comparative Example 1, the surface of the film having the reversible thermosensitive recording layer opposite to the recording layer side and Sunroid Vip R-1700 (200 μm thick PVC sheet) manufactured by Tsutsunaka Plastics Industry Co., Ltd. were thermoset. The same film (200 μm thick PVC sheet) was bonded in-line using an epoxy-based adhesive, and the same film was similarly bonded in-line. After aging thermosetting, a reversible thermosensitive recording medium having a total thickness of about 610 μm was obtained. Was cut into a card size to make a card.

Using the reversible thermosensitive recording medium card prepared as described above, the printing mechanism is a line type thermal head (8 dots / mm, printing energy 0.4 mj / do).
t), the erasing device is hot stamped with chloroprene rubber (1 mm thick) as shown in FIG.
(Erase temperature 100 ° C., contact time 0.5 sec, pressure 0.
5 kgf / cm ² ) Printing and erasing on the card was repeated 50 times. The results and the state of initial curl are shown in Table 1, and the state of deformation after immersing each film in silicone oil at 80 ° C. for 5 minutes is shown in Table 2.

[0069]

[Table 1]

[0070]

[Table 2]

[0071]

As is apparent from the above detailed and concrete description, the present invention has a resin base material on a support and an organic low-molecular substance dispersed in the resin base material as a main component, and is temperature-dependent. In a reversible thermosensitive recording material provided with a thermosensitive layer which changes reversibly between a transparent state and a cloudy state, the support is formed by laminating three sheets via an adhesive layer, and the total thickness is 600 μm.
m and 1000 μm or less, the initial and repeated recording, less curl after erasure,
This is an extremely excellent effect that a reversible thermosensitive recording medium that does not undergo thermal deformation even when heated and pressed by an erasing device such as a hot stamp can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a typical example of a temperature-transparency change curve of a reversible thermosensitive recording material used in the present invention.

FIG. 2 is a diagram showing a basic configuration of a reversible thermosensitive recording material of the present invention.

FIG. 3 is a view showing an example in which a magnetic recording layer is formed on a support of the present invention.

FIG. 4 is a diagram showing an example of an erasing device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal recording layer 2 Support 3 Film 4 Film 5 Film 6 Adhesive layer 7 Light reflective layer or coloring agent layer 8 Magnetic recording layer 9 Thermal recording medium 10 Hot stamp 10 'Stamp stand 11 Electric heater 12 Temperature sensor 13 Chloroprene rubber ( Hardness 40)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C005 HA08 HB04 JC02 KA02 KA15 KA61 LA05 LB06 LB25 2H026 AA01 AA28 EE05 FF01 FF25 GG01 2H111 HA07 HA18 HA23 HA34

Claims (4)

[Claims] 1. A reversible thermosensitive recording medium having at least a resin on a support and a thermosensitive layer whose transparency reversibly changes depending on temperature, wherein the support comprises a first sheet, a second sheet, The third sheet is laminated in the order, and the total thickness is 6
A reversible thermosensitive recording medium having a thickness of at least 00 μm and at most 1,000 μm, and having a deformation of 0.5 mm or less after immersion of the first and third sheets in dimethyl silicone oil heated to 80 ° C. for 5 minutes. 2. A reversible thermosensitive recording medium comprising a support and a thermosensitive layer containing at least a resin and having a reversible change in transparency depending on temperature, wherein the support comprises a three-layer sheet and an adhesive layer. And the total thickness is 600 μm or more and 1
A reversible thermosensitive recording medium having a thickness of not more than 000 μm and a deformation of not more than 0.5 mm after each sheet to be bonded is immersed in dimethyl silicone oil heated to 80 ° C. for 5 minutes. 3. The reversible thermosensitive recording medium according to claim 1, wherein a magnetic recording layer is provided on any part of the support. 4. A method for recording and erasing an image on a reversible thermosensitive recording medium, wherein the image is recorded and erased by heating using the reversible thermosensitive recording medium according to claim 1.