JPH0648031A - Reversible thermal recording medium - Google Patents

Abstract

PURPOSE:To obtain a reversible thermal recording medium which makes a sharp contrast in an image and has an excellent display part for repeated formation and erasure of an image, with a printed part with a superb color tone provided on a magnetic recording layer. CONSTITUTION:The reversible thermal recording medium is composed of a thermosensitive layer 1 whose transparency changes reversibly due to heat laminated on one surface of a support 2 and a magnetic recording layer 3, a whitening layer 4 and a printing layer 5 laminated sequentially on the other surface.

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 medium capable of magnetic recording and capable of reversibly displaying an image by utilizing reversible change in transparency due to heat.

[0002]

2. Description of the Related Art In recent years, reversible heat-sensitive recording materials have been attracting attention because they can form images temporarily and can erase the images when they are no longer needed. As a typical example, the glass transition temperature (Tg) is from 50 to 60 ° C. to 8
A reversible thermosensitive recording medium in which an organic low molecular weight substance such as a higher fatty acid is dispersed in a resin base material such as a vinyl chloride-vinyl acetate copolymer having a low glass transition temperature of less than 0 ° C. is known (special feature: JP-A-54-119377, JP-A-55-1
54198 and the like).

Various types of cards have been issued and used in large quantities, and examples thereof include a business card-sized telephone card and a so-called orange card (a ticket sales card of JR Co.). For these cards (magnetic cards), for example, 1, 50, ... 300 ,.
Numbers such as 0, ... Are printed, and the balance after use is displayed by the holes shown between these numbers. Therefore, although the balance can be accurately known by using a telephone or a ticket vending machine which can use these cards, in other cases, the balance cannot be accurately grasped.

In order to eliminate such inconvenience to some extent, a card in which the balance is displayed numerically by a thermal head by using a heat-sensitive layer using a leuco dye or a heat-sensitive layer Sn-deposited on a magnetic recording layer is practically used. (Japanese Patent Laid-Open No. 59-
199284, JP-A-60-18388 and the like). However, although these display methods can display the balance but cannot erase it, the amount of information that can be recorded is limited. Therefore, there is a drawback that the balance cannot be displayed despite the balance.

The present inventors have previously proposed an information recording display medium capable of displaying and erasing a balance by using a thermosensitive layer having a property that the transparency reversibly changes depending on the temperature (Japanese Patent Laid-Open No. Hei 10 (1999) -242242). 3-130188). However, in such an information storage display medium, when the printing layer is provided on the surface opposite to the white support provided with the magnetic recording layer, the back surface is white, so that the color tone of the printed portion is clear. Since the light-reflecting layer is provided on the magnetic recording layer, and the heat-sensitive layer is further provided on the light-reflecting layer, in order to accurately read and write information on the magnetic recording layer, the heat-sensitive layer laminated on the magnetic recording layer is Since the thickness is limited, the thickness of the heat sensitive layer provided on the magnetic recording layer cannot be increased, and good image contrast cannot be obtained.

Also, a magnetic recording layer provided with a heat sensitive layer on the opposite side of the support has been previously proposed (JP-A-58-45998). In this case, the thickness of the heat-sensitive layer is not limited, so the thickness of the heat-sensitive layer can be increased and good image contrast can be obtained.However, when a printing layer is further provided on the magnetic recording layer, the magnetic layer Since the recording layer is generally black or brown (including brown), there is a disadvantage that the color tone of the printed portion is deteriorated and becomes opaque.

[0007]

DISCLOSURE OF THE INVENTION The present invention has solved the above-mentioned drawbacks, has a good contrast of an image formed on a display portion, is excellent in repeating the formation and erasure of the image, and is excellent in the magnetic recording layer. An object of the present invention is to provide a reversible thermosensitive recording medium in which the color tone of the printing portion is less deteriorated and the printing portion is clear even when the printing portion is provided.

[0008]

According to the present invention, a heat-sensitive layer whose transparency is reversibly changed by heat is laminated on one surface of a support, and a magnetic recording layer, a white colored layer, and Provided is a reversible thermosensitive recording medium, which is obtained by sequentially laminating printing layers. Further, a light reflection layer or a coloring layer is provided between the support and the thermosensitive layer, and the thermosensitive layer is provided on the thermosensitive layer. There is provided a reversible thermosensitive recording medium characterized in that a protective layer is laminated and a protective layer is laminated on the printed layer. Further, a transparent support is used as the support, and the support and the magnetic layer are used. The reversible thermosensitive recording medium is provided with a light reflecting layer or a coloring layer provided between the recording layer and the recording layer.

That is, in the reversible thermosensitive recording medium of the present invention, as shown in FIG. 1, a thermosensitive layer 1 is laminated on a support 2, and a magnetic recording layer 3 and a white colored layer 4 are provided on the opposite surface of the support. A reversible thermosensitive recording medium in which printing layers 5 are sequentially laminated, and a light reflection layer between the support 2 and the thermosensitive layer 1 of the reversible thermosensitive recording medium of FIG. 1 as shown in FIG. Alternatively, a colored layer 8 is provided, a protective layer 10 is laminated on the heat-sensitive layer 1 of the reversible thermosensitive recording medium shown in FIG. 1, and as shown in FIG. The printing protective layer 7 is laminated on the printing layer 5 of the thermosensitive recording medium, and the opposite surface of the support 2 provided with the thermosensitive layer 1 of the reversible thermosensitive recording medium of FIG. 1 as shown in FIG. A reversible thermosensitive recording medium comprising a colored layer 12 provided between the support 2 and the magnetic recording layer 3. .

The reversible thermosensitive recording medium of the present invention will be described in more detail below. As shown in FIG. 1A, by stacking the white colored layer 4 and the printed layer 5 on the magnetic recording layer 3 in this order, the color tone of the printed portion is brought out by the white colored layer 4 on the back side and printed. I found that the part became clear. When the adhesiveness between the support 2 and the heat sensitive layer 1 is poor, an adhesive layer 6 may be provided between the support 2 and the heat sensitive layer 1 as shown in FIG. 1 (b). When the adhesiveness between the support 2 and the magnetic recording layer 3 is poor, an adhesive layer 6 may be provided between the support 2 and the magnetic recording layer 3 as shown in FIG. 1 (c). Furthermore, in order to protect the print layer 5 from peeling and scratches, as shown in FIG. 1D, a print protective layer 7 (UV curable resin, electron beam curable resin, OP It is also possible to provide a varnish).

Further, as shown in FIG. 2A, in the case where the light reflection layer / coloring layer 8 is provided between the support 2 and the heat sensitive layer 1, the light reflection layer is the light reflection layer. Increase the amount,
The effect of improving the visibility is further enhanced, and the coloring layer can be attached to the back surface of the image part or the background part when the background part or the image part is in a transparent state, and the visibility can be improved. In addition, in order to protect the print layer 5 from peeling and scratches, a print protection layer 7 is formed on the print layer 5 as shown in FIG. 2B.
Can be provided. Furthermore, when the light reflection layer / colored layer 8 is provided on the support 2 having the surface of the support 2 having irregularities,
Light is diffusely reflected by the unevenness and the contrast is lowered. Therefore, as shown in FIG. 2C, a smoothing layer 9 is provided between the support 2 and the light reflection layer / coloring layer 8 to provide unevenness on the surface of the support 2. Since the contrast of the light reflection layer / colored layer 9 is improved by providing the light reflection layer / colored layer 8 after smoothing, the smooth layer is provided between the support 2 and the light reflection layer / colored layer 8. Can be provided.

Further, FIG. 3 (a) shows that the protective layer 10 is laminated on the heat sensitive layer 1 of FIG. 1 (a), and the heat sensitive layer 1 is scratched, peeled, erased, etc. Can be eliminated, and the durability of the image portion when repeated many times can be improved. Furthermore, by stacking the print protection layer 7 on the print layer 5 as shown in FIG. 3B, peeling, scratches, etc. of the print layer 5 can be protected. Furthermore, as shown in FIG. 3C, an intermediate layer 11 is provided between the protective layer 10 and the heat-sensitive layer 1 in order to protect the heat-sensitive layer 1 from the solvent, monomer components, etc. used in the protective layer 10. You can also

In FIG. 4, the print protection layer 7 is laminated on the print layer 5, and it is possible to protect the print layer 5 from scratches, peeling, etc., which may occur when it is repeated many times.

In FIG. 5, a coloring layer 12 is provided between the support 2 and the magnetic recording layer 3, which is opposite to the surface of the transparent support 2 on which the heat sensitive layer 1 is provided. By providing the colored layer 12 on the surface, the color of the back side of the image part of the heat-sensitive layer 1 can be changed to, for example, red, blue, green, etc., so that a white image can be formed on a blue background part and a colored display part can be formed. can do.

Further, in the structure shown in FIG. 6, the light reflecting layer / coloring layer 8 is provided at least in part between the support 2 having a visible light transmittance of 50% or more and another support 15. The reversible thermosensitive recording medium is provided with an adhesive layer 14 that is in close contact with and integrated with the exposed surface, and the inside between at least a part of the light reflecting layer / coloring layer 8 and the support 2 having a visible light transmittance of 50%. By providing the non-adhesive portion having the air layer 15 in the above, the refractive index of the organic polymer material used as the main component of the heat sensitive layer is 1.
It is about 4 to 1.6 and has a large difference from the refractive index of 1.0 of air, so light is reflected at the interface between the heat-sensitive member and the non-adhesive portion, and the white turbidity when the heat-sensitive layer is cloudy is amplified, Since the visibility is improved, this non-adhered portion can be used as the display portion. Further, since the non-adhesion portion has air inside the non-adhesion portion, the non-adhesion portion serves as a heat insulating layer, and the thermal sensitivity is improved. In addition, the non-adhesive area also serves as a cushion, and even if pressure is applied with a thermal head, the pressure actually applied to the heat-sensitive member will be low, and the deformation of the resin base material will be small even if heat is applied. Repeated durability is improved without particle expansion. The transparent support 2 is 20 to 300.
A thickness of μm is preferable, and if it is thicker than this, the non-adhesive part loses the role of a cushion and the repeated durability decreases, and if the support of the heat-sensitive member is too thin, the curl of the support after coating becomes large. Therefore, the colored layer / light reflecting layer 8
Adhesion with is poor. If you change the colored layer to a light reflection layer,
The amount of light reflection increases, and the effect of improving visibility is further enhanced.

In the reversible thermosensitive recording medium shown in FIG.
If the heat-sensitive member and the colored or light-reflecting member are configured as separate members, a positional deviation between the display unit and the non-adhesive portion may occur,
It is desirable to configure it as one unit, which improves the convenience of handling. In order to bring the heat-sensitive member and the colored or light-reflecting member into close contact with each other, it is possible to use a method of adhering the parts other than the non-contact parts with an adhesive having good adhesiveness. Further, if the support having a visible light transmittance of less than 50% is used, the transparency of the background portion is lowered and the contrast is deteriorated. Therefore, by using a support having a visible light transmittance of 50% or more, the transparency of the background portion (transparent state) is improved and the contrast is improved.

The reversible thermosensitive recording material of the present invention utilizes the transparency change (transparent state, cloudy opaque state) as described above, and the difference between the transparent state and the cloudy opaque state is presumed as follows. . That is, (i) in the case of transparency, the particles of the organic low-molecular substance dispersed in the resin matrix are composed of large particles of the organic low-molecular substance, and the light incident from one side is not scattered and is opposite. It appears to be transparent because it is transmitted to the side, and (ii) in the case of turbidity, the particles of the organic low-molecular substance are composed of polycrystals of fine crystals of the organic low-molecular substance, and the crystal axis of each crystal Since the light is directed in various directions, the light incident from one side is refracted many times at the interface of the crystal of the organic low molecular weight substance particles, and is scattered and thus appears white.

In FIG. 7 (representing the change in transparency due to heat), the heat-sensitive portion mainly composed of a resin base material and an organic low molecular weight substance dispersed in the resin base material is, for example, T
It is cloudy and opaque at room temperature below ₀ . This is the temperature T ₂
When it is heated to ₀ , it becomes transparent, and even if it is returned to room temperature below T _{0 in} this state, it remains transparent. This is the temperature T ₂ to T ₀
It is considered that the organic low molecular weight substance is in a semi-molten state until the following and the crystal grows from a polycrystal to a single crystal.
Upon further heating to T ₃ or more temperature becomes translucent state intermediate between the maximum transparency and the maximum opacity. Next, when this temperature is lowered, the first cloudy opaque state is restored without taking the transparent state again. It is considered that this is because when the organic low molecular weight substance is melted at a temperature of T ₃ or higher, the polycrystal is deposited by being cooled. When this opaque state is heated to a temperature between T _{1 and} T ₂ and then cooled to room temperature, that is, a temperature of T ₀ or lower, an intermediate state between transparent and opaque can be obtained. Also, the transparent material that has become transparent at room temperature returns to the cloudy and opaque state again when heated to a temperature of T ₃ or higher and then returned to room temperature. That is, both opaque and transparent forms at room temperature and intermediate forms thereof can be obtained.

Therefore, the heat-sensitive part can be selectively heated by selectively applying heat to form a cloudy image on a transparent background and a transparent image on a cloudy background, and the change can be repeated many times. It is possible. By arranging a colored sheet on the back surface of such a heat-sensitive body, it is possible to form an image of the color of the colored sheet on a white background or an image of the white background on the background of the colored sheet. 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.

To form the heat-sensitive layer of the reversible heat-sensitive recording medium of the present invention, for example, a transparent or white plastic film such as a polyester film, paper or the like or colored products thereof, a gold plate, a glass plate, etc. can be prepared by the following method. The heat-sensitive layer can be formed as a film on the support or can be formed into a sheet. 1) A method in which a resin base material and an organic low molecular weight substance are dissolved in a solvent, which is applied onto a support and the solvent is evaporated to form a film or sheet. 2) Dissolve the resin base material in a solvent that dissolves only the resin base material, 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 the method of making a sheet. The solvent for forming the heat-sensitive layer can be variously selected depending on the types of the resin base material and the organic low molecular weight substance, and examples thereof include tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, chloroform, carbon tetrachloride, ethanol, toluene, benzene and the like. In addition, when the dispersion is used, of course, the organic low-molecular-weight substance is precipitated as fine particles in the heat-sensitive part obtained when the solution is used,
Exists in a distributed state.

In the present invention, the resin used as the resin base material of the thermosensitive layer of the reversible thermosensitive recording medium is preferably a resin which can form a film or a sheet, has good transparency and is mechanically stable. Examples of such resins include polyvinyl chloride; vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride-acrylate copolymer. Vinyl chloride-based copolymers such as polymers; polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymers, vinylidene chloride-based copolymers such as vinylidene chloride-acrylonitrile copolymers; polyesters; polyamides; polyacrylates or polymethacrylates or acrylates -Methacrylate copolymer; silicone resin and the like can be mentioned. These may be used alone or in admixture of two or more.

On the other hand, as the organic low molecular weight substance, any substance that changes from polycrystal to single crystal due to heat in the heat sensitive portion (changes within the temperature range of T _{1 to} T ₃ shown in FIG. 7) may be used.
Generally, those having a melting point of 30 to 200 ° C., preferably about 50 to 150 ° C. are used. Such organic low molecular weight substances include alkanols; alkane diols; halogen alkanols or halogen alkane diols; alkylamines; alkanes; alkenes; alkynes; halogen alkanes; halogen alkenes; halogen alkynes; cycloalkanes; cycloalkenes; cycloalkynes; saturated or 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; halogenallylcarboxylic acids or Of their esters, amides or ammonium salts; thioalcohols; thiocarboxylic acids or their esters, amides or ammonium salts; of thioalcohols Carboxylic acid esters, and the like. These may be used alone or in admixture of two or more. The carbon number of these compounds is 10
60, preferably 10-38, particularly 10-30 are preferred. The alcohol group moiety in the ester may be saturated or unsaturated, and may be halogen-substituted. In any case, the organic low molecular weight substance is at least one of oxygen, nitrogen, sulfur and halogen in the molecule, for example, -OH, -COOH, -CONH, -COOR, -N.
_{H, -NH 2, -S -,} - S-S -, - O-, is preferably a compound containing a halogen and the like.

More specifically, as these compounds,
Uric acid, dodecanoic acid, myristic acid, pentadecane
Acid, palmitic acid, henicosanoic acid, tricosanoic acid,
Gnoceric acid, pentacosanoic acid, cerotic acid, montan
Acid, melissic acid, stearic acid, behenic acid, nonadecane
Higher fatty acids such as acids, araginic acid, oleic acid; steari
Methyl acid salt, tetradecyl stearate, stearic acid
Octadecyl, octadecyl laurate, palmitic acid
Higher fatty acids such as tetradecyl and dodecyl behenate
Tell; C₁₆H₃₃-OC₁₆H₃₃ , C₁₆H₃₃-SC
₁₆H₃₃ , C₁₈H₃₇-SC₁₈H₃₇ , C₁₂H_{twenty five}-S
-C₁₂H_{twenty five} , C₁₉H₃₉-SC₁₉H₃₉ , C₁₂H_{twenty five}
-S-S-C₁₂H_{twenty five} ， Etc., such as ether or thioether. Above all, the present invention
Then higher fatty acids, especially palmitic acid, heneicosane
Acid, tricosanoic acid, lignoceric acid, pentadecanoic acid,
Nonadecanoic acid, arachidic acid, stearic acid, behenic acid, etc.
Is preferably a higher fatty acid having 16 or more carbon atoms, and has 16 carbon atoms.
-24 higher fatty acids are more preferred.

In order to widen the range of temperature at which the material can be made transparent, the organic low molecular weight substances described in this specification may be appropriately combined, or such organic low molecular weight substances may be combined with other materials having different melting points. Good. These are disclosed in, for example, JP-A-63-39378, JP-A-63-130380, and Japanese Patent Application No. 1-140109, but the invention is not limited thereto.

The weight ratio of the organic low molecular weight substance to the resin base material in the heat sensitive layer is preferably about 2: 1 to 1:16, more preferably 1: 1 to 1: 5. If the ratio of the resin base material is below this range, it will be difficult to form a film in which the organic low molecular weight material is retained in the resin base material. Becomes difficult.

The thickness of the heat sensitive layer is preferably 1 to 30 μm,
2 to 20 μm is more preferable. If the heat-sensitive layer is too thick, heat distribution will occur in the heat-sensitive layer, and it will be difficult to achieve uniform transparency. On the other hand, if the heat-sensitive layer is too thin, the white turbidity is lowered and the contrast is lowered. Further, the white turbidity can be increased by increasing the amount of the organic low molecular weight substance in the heat sensitive layer.

In addition to the above components, additives such as a surfactant and a high boiling point solvent may be added to the heat-sensitive layer in order to facilitate the formation of a transparent image. Specific examples of these additives are as follows. Examples of high boiling point solvents: tributyl phosphate, tri-2-phosphate
Ethylhexyl, triphenyl phosphate, tricresyl phosphate, butyl oleate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, di-n-octyl phthalate, di-2-ethylhexyl phthalate, diisononyl phthalate , Dioctyldecyl phthalate, diisodecyl phthalate, butylbenzyl phthalate,
Dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, di-2 azelaate
-Ethylhexyl, dibutyl sebacate, di-2-ethylhexyl sebacate, diethylene glycol dibenzoate, triethylene glycol di-2-ethyl butyrate, methyl acetylricinoleate, butyl acetylricinoleate, butylphthalylbutyl glycolate, acetylcitric acid Tributyl.

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 salt of higher alkylbenzene sulfonic acid; higher fatty acid, aromatic carboxylic acid, higher fatty acid sulfonic acid, aromatic sulfonic acid, sulfuric acid monoester Or Ca, Ba or Mg salt of phosphoric acid mono- or di-ester; low degree of sulfated oil; poly long chain alkyl acrylate; acrylic orgomer; poly long chain alkyl methacrylate; long chain alkyl methacrylate to amine-containing mono Chromatography copolymers; styrene-maleic anhydride copolymer; olefin-maleic anhydride copolymer.

In the reversible thermosensitive recording medium of the present invention, the magnetic recording layer is formed by depositing a magnetic material on a support by a method such as vacuum deposition and sputtering, or by coating the magnetic material with a resin binder and drying it. Can be formed. Examples of the magnetic material include iron, cobalt and the like, and alloys or compounds thereof. Examples of the resin binder include various thermoplastic resins, thermosetting resins, ultraviolet curable resins, and electron beam curable resins.

The white colored layer in the reversible thermosensitive recording medium of the present invention is composed mainly of a colorant and a resin binder, and its forming method is as follows. That is, in order to form the white colored layer, a solution or dispersion containing a colorant and a resin binder as main components is applied onto the magnetic recording layer and dried. Examples of the colorant include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, kaolin, talc, surface-treated inorganic fine powder such as calcium and silica, and the like. , Urea-formalin resin, styrene / methacrylic acid copolymer, polystyrene resin, vinylidene chloride resin, and other organic fine powders. Further, as the resin binder, various thermoplastic, thermosetting or ultraviolet curable resins are used.

To accurately write and read the magnetic recording, the distance from the magnetic head to the surface of the magnetic recording layer is about 10 μm.
The following is desirable. If it is 10 μm or more, it becomes difficult to accurately write and read magnetic recording. Therefore, in the example shown in FIG. 1, the total thickness of the white colored layer and the print layer or the print protection layer is about 10 in total.
It is desirable that the thickness is μm or less. The whiteness of the white colored layer is preferably 0.3 or less, more preferably 0.2 or less, and particularly preferably 0.16 or less with a Macbeth reflection densitometer.

A solvent or the like may be used for forming the smooth layer, and the solvent in this case may be the same as the solvent for forming the heat sensitive layer 1. Further, instead of these solvents, a photopolymerizable monomer can be used for easy handling. As the photopolymerizable monomer, 2-ethylhexyl acrylate, cyclohexyl acrylate, butoxyethyl acrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, etc. Is mentioned. An ultraviolet curable resin is also used for forming the smooth layer, and as the ultraviolet curable resin, any monomer or oligomer (or prepolymer) which undergoes a polymerization reaction upon irradiation with ultraviolet rays and is cured to be a resin can be used. Examples of such monomers or oligomers include (poly) ester acrylate, (poly) urethane acrylate, epoxy acrylate, polybutadiene acrylate, silicone acrylate, and melamine acrylate.

(Poly) ester acrylates are polyhydric alcohols such as 1,6-hexanediol, propylene glycol (as propylene oxide), diethylene glycol and polybasic acids such as adipic acid, phthalic anhydride, trimellitic acid and acrylic acid. It is a reaction of and. The structural examples are shown in (a) to (c). (a) Adipic acid / 1,6-hexanediol / acrylic acid

[Chemical 1] (b) Phthalic anhydride / Propylene oxide / Acrylic acid

[Chemical 2] (c) trimellitic acid / diethylene glycol / acrylic acid

[Chemical 3] The (poly) urethane acrylate is obtained by reacting a compound having an isocyanate group such as tolylene diisocyanate (TDI) with an acrylate having a hydroxy group. An example of the structure is shown in (d). HEA is an abbreviation for 2-hydroxyethyl acrylate, HDO is an abbreviation for 1,6-hexanediol, and ADA is an abbreviation for adipic acid. (d) HEA / TDI / HDO / ADA / HDO / TDI / HEA

[Chemical 4] Epoxy acrylates are roughly classified into bisphenol A type, novolac type, and alicyclic type according to the structure. Epoxy groups of these epoxy resins are esterified with acrylic acid to make a functional group an acryloyl group. Its structural example (e)
~ (G). (e) Bisphenol A-epichlorohydrin type / acrylic acid

[Chemical 5] (f) Phenol novolac-epichlorohydrin type / acrylic acid

[Chemical 6] (g) Alicyclic / acrylic acid

[Chemical 7] Polybutadiene acrylate is obtained by reacting 1,2-polybutadiene having terminal OH groups with isocyanate, 2-mercaptoethanol or the like, and then further reacting with acrylic acid or the like. An example of the structure is shown in (h). (h)

[Chemical 8] The silicone acrylate is, for example, methacryl-modified by a condensation reaction (demethanol reaction) between an organofunctional trimethoxysilane and a silanol group-containing polysiloxane, and a structural example thereof is shown in (i). (i)

[Chemical 9] On the other hand, as the material of the electron beam curable resin, the ultraviolet curable resin can be used as it is.

By the way, the electron beam has a larger energy and a larger penetrating power than ultraviolet rays. Therefore, especially when a pigment or the like is put in the smooth layer, the electron beam can reach the inside. In this way, electron beam curing can form a more dense and uniform network structure than ultraviolet curing, and thus it can be expected to exhibit further excellent durability. Also,
The energy required for curing electron beams is about 3 compared to ultraviolet rays.
Although it is only one-third, capital investment is large, but if demand is high, it can be expected to reduce costs.

As the colored layer, a paper or film colored entirely, or a paper or film colored on a support by coating or printing is used. Its colors are black, blue,
Any color such as green or red can be used. Further, the light reflecting layer is provided when an image is used as a reflection image, and the contrast can be increased even if the thickness of the heat sensitive layer is reduced. To provide the light reflecting layer, specifically, Al,
A method of vapor-depositing Ni, Sn, etc. may be mentioned (Japanese Patent Laid-Open No. Sho 64).
-14079).

Further, on the heat-sensitive layer of the present invention, the surface is prevented from being deformed by the heat and pressure of the heating means such as a thermal head by the writing method and the transparency of the transparent portion is lowered, or the print layer is protected. For this purpose, a protective layer or a print protective layer may be provided. Materials for these protective layers (thickness 0.1 to 5 μm) include silicone rubber and silicone resin (JP-A-63-63).
No. 221087), a polysiloxane graft polymer (described in JP-A-63-317385), an ultraviolet curable resin or an electron beam cured resin (described in JP-A-2-566), and the like. In any case, a solvent is used at the time of coating, but it is desirable that the solvent is difficult to dissolve the resin base material of the heat sensitive layer and the organic low molecular weight substance. As a solvent in which the resin of the heat sensitive layer and the organic low molecular weight substance are difficult to dissolve, n-hexane, methyl alcohol, ethyl alcohol,
Isopropyl alcohol and the like can be mentioned, and an alcohol solvent is particularly preferable from the viewpoint of cost.

Further, an intermediate layer may be provided between the protective layer and the heat-sensitive layer in order to protect the heat-sensitive layer from the solvent and the monomer component of the protective layer-forming liquid (JP-A-1-13378).
No. publication). As the material for the intermediate layer, the following thermosetting resins and thermoreversible resins can be used in addition to those listed as the resin base material in the thermosensitive layer. That is, specifically, polyethylene, polypropylene, polystyrene, polyvinyl alcohol, polyvinyl butyral, polyurethane, saturated polyester, unsaturated polyester, epoxy resin, phenol resin, polycarbonate, polyamide and the like can be mentioned. The thickness of the intermediate layer varies depending on the use, but is preferably about 0.1 to 2 μm. Below this,
The protective effect decreases, and if it exceeds this, the thermal sensitivity decreases.

[0038]

EXAMPLES The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. In addition, both parts and% are based on weight.

Example 1 Transparent PET with a thickness of about 188 μm (visible light transmittance 76%
Toray's Lumirror T type) on stearic acid 5 parts eicosane diacid 5 parts diisodecyl phthalate 3 parts vinyl chloride-vinyl acetate-phosphoric acid ester copolymer 39 parts (Denka vinyl # 1000P manufactured by Denki Kagaku Kogyo) T ． H. A solution of 100 parts of F (tetrahydrofuran) and 65 parts of toluene was applied and dried by heating to provide a heat-sensitive layer (reversible heat-sensitive recording layer) having a thickness of about 10 μm. Then r-Fe ₂ O ₃ 10 parts of vinyl chloride on a transparent PET opposite surface - vinyl acetate - vinyl alcohol copolymer 10 parts (UCC Co.: VAGH) 2 parts Isocyanate (manufactured by Nippon Polyurethane Co., Coronate L50% toluene solution ) Methyl ethyl ketone 40 parts Toluene 40 parts is applied with a wire bar and dried by heating to about 1
A magnetic recording layer having a thickness of 0 μm was provided. Titanium oxide 10 parts UV curable resin (FS-1059 manufactured by Mitsubishi Rayon Co., Ltd.) 5 parts Toluene 10 parts dispersion liquid was offset-printed and irradiated with UV light for 5 seconds with a 120 W / cm UV lamp to cure. About 5 μm
A thick white colored layer was provided. Furthermore, a printing layer was provided thereon by offset printing to prepare a reversible thermosensitive recording medium.

Example 2 A reversible thermosensitive film was prepared in the same manner as in Example 1 except that Al was vacuum-deposited to a thickness of about 400 Å and a light reflecting layer was provided between the support and the thermosensitive layer. A recording medium was created.

Example 3 A solution of 10 parts of polyamide resin (CM8000, manufactured by Toray Industries, Inc .: CM8000) and 90 parts of methanol was applied on the heat-sensitive layer of Example 1 and dried by heating to form an intermediate layer having a thickness of 1 μm. Furthermore, a solution comprising 10 parts of a 75% butyl acetate solution of a urethane acrylate-based UV-curable resin (Dainippon Ink and Chemicals, Unidick C7-157) toluene 10 parts was applied with a wire bar, and after heating and drying, 8
A reversible thermosensitive recording medium was prepared in the same manner as in Example 1 except that it was cured with a 0 W / cm ultraviolet lamp and a protective layer having a thickness of about 2 μm was provided.

Example 4 OP varnish (New Dicure GP OP varnish FT (manufactured by Dainippon Ink and Chemicals, Inc.)) was offset-printed on the printing layer of Example 1 as a print protection layer, and U of 120 W / cm was applied.
A reversible thermosensitive recording medium was prepared in the same manner as in Example 1 except that it was cured by irradiation with UV light for 5 seconds with a V lamp.

Example 5 A reversible thermosensitive recording medium was prepared in the same manner as in Example 1 except that a black colored layer formed by printing was provided between the support of Example 1 and the magnetic recording layer.

Example 6 Behenic acid 6 parts Eicosane diacid 4 parts Vinyl chloride-vinyl acetate copolymer 30 parts on a transparent polyester film (visible light transmittance 83%, manufactured by Toray Industries: Lumirror T type) having a thickness of about 50 μm. Tetrahydrofuran 150 parts A solution of 3 parts of diisodecyl phthalate was applied and dried by heating to provide a heat-sensitive layer having a thickness of 10 μm. In addition, the support is made of white PET having a thickness of 188 μm.
A magnetic recording layer, a white coloring layer, and a printing layer similar to those in Example 1 were provided except that a film (Toray mirror E-20) was provided, and about 400Å was formed in the center of a 188 μm thick white polyester film on the opposite surface of the support. Al was vapor-deposited on to prepare a light reflection layer. Then, a vinyl chloride-vinyl acetate-vinyl alcohol copolymer (VAGH manufactured by UCC) is printed as an adhesive on the portion where the light reflection layer is not present, and the reversible thermosensitive recording material is obtained by superposing and heating the heat-sensitive members and adhering them together. Created. At that time, a non-adhesive portion having air inside was formed between the heat-sensitive member and the coloring member in the portion corresponding to the black printed portion which was not adhered.

Example 7 The transparent PET film having a thickness of about 50 μm obtained in Example 6 was used in an amount of about 2
A reversible thermosensitive recording medium was prepared in the same manner as in Example 6 except that a PET film having a thickness of 5 μm (manufactured by Toray Industries, Inc .: Lumirror T type: visible light transmittance 85%) was used.

Example 8 About 1 μm of the transparent PET film of Example 6 having a thickness of about 50 μm was prepared.
A reversible thermosensitive recording medium was prepared in the same manner as in Example 6 except that a transparent PET film having a thickness of 88 μm (manufactured by Toray Industries, Inc .: Lumirror T type: visible light transmittance 76%) was used.

Example 9 About 1 μm of the transparent PET film having a thickness of about 50 μm of Example 6 was prepared.
A reversible thermosensitive recording medium was prepared in the same manner as in Example 6 except that a transparent PET film having a thickness of 00 μm (manufactured by Toray Industries, Inc .: Lumirror # 100S type: visible light transmittance 59%) was used.

Comparative Example 1 A reversible thermosensitive recording medium was prepared in the same manner as in Example 1 except that the white colored layer was not provided.

Next, for the reversible thermosensitive recording media of Examples 1 to 9 and Comparative Example 1, when an image was formed by applying 1 mj / dot of energy with a thermal head to the heat sensitive layer in the color tone and transparent state of the printed part. Image contrast and scratches, peeling and 10
The durability of the heat-sensitive layer when the image was repeatedly formed and erased repeatedly was visually determined, and the results are shown in Table 1.

[0050]

[Table 1]

[0051]

As is clear from the description of the examples and comparative examples, the reversible thermosensitive recording medium of the present invention provides a high contrast rewritable display, and by providing a white colored layer on the magnetic layer. A reversible thermosensitive recording medium in which the color tone of the printed portion does not deteriorate and the printed portion is clear.

[Brief description of drawings]

1A to 1D are specific schematic cross-sectional views of a reversible thermosensitive recording medium according to claim 1 of the present invention.

2 (a) to (c) are specific schematic cross-sectional views of a reversible thermosensitive recording medium according to claim 2 of the present invention.

3 (a) to (c) are specific schematic cross-sectional views of the reversible thermosensitive recording medium according to claim 3 of the present invention.

FIG. 4 is a schematic sectional view of a reversible thermosensitive recording medium according to claim 4 of the present invention.

FIG. 5 is a schematic sectional view of a reversible thermosensitive recording medium according to claim 5 of the present invention.

FIG. 6 is a schematic cross-sectional view of a reversible thermosensitive recording medium having a light-reflecting layer or a colored layer provided with a non-adhesive portion having an air layer in the support of the present invention.

FIG. 7 is a diagram showing changes in transparency of a reversible thermosensitive recording medium according to the present invention due to heat.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Heat sensitive layer 2 ... Support body 3 ... Magnetic recording layer 4 ... White colored layer 5 ... Printing layer 6 ... Adhesive layer 7 ... Printing protective layer 8 ... Light reflection layer / colored layer 9 ... Smoothing layer 10 ... Protective layer 11 ... Intermediate Layer 12 ... Colored layer 13 ... White support 14 ... Adhesive layer 15 ... Air layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuya Amano 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (5)

[Claims] 1. A heat-sensitive layer, the transparency of which is reversibly changed by heat, is laminated on one surface of a support, and a magnetic recording layer, a white coloring layer, and a printing layer are sequentially laminated on the opposite surface thereof. A reversible thermosensitive recording medium. 2. The reversible thermosensitive recording medium according to claim 1, wherein a light reflecting layer or a coloring layer is provided between the support and the thermosensitive layer. 3. The reversible thermosensitive recording medium according to claim 1, wherein a protective layer is laminated on the thermosensitive layer. 4. The reversible thermosensitive recording medium according to claim 1, wherein a print protection layer is laminated on the print layer. 5. The reversible thermosensitive material according to claim 1, wherein a transparent support is used as the support, and a light reflecting layer or a coloring layer is provided between the support and the magnetic recording layer. recoding media.