JP3295746B2 - Reversible thermosensitive recording medium and image recording method using the same - Google Patents

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 which causes a reversible change in transparency or color tone with temperature.
Also, the present invention relates to an image recording method capable of obtaining clear recording even when the reversible thermosensitive recording medium is used for a long time and repeatedly.

[0002]

2. Description of the Related Art In recent years, reversible thermosensitive recording media capable of temporarily forming an image and erasing the image when it is no longer needed have attracted attention. As a typical example, a reversible thermosensitive recording medium in which a low-molecular organic substance such as a higher fatty acid is dispersed in a resin base material such as a vinyl chloride-vinyl acetate copolymer has been known (Japanese Patent Application Laid-Open No. Sho 54/1979). -11
9377, JP-A-55-154198 and the like).

However, in such a conventional reversible thermosensitive recording medium (hereinafter sometimes simply referred to as a “recording medium”), when an image is repeatedly formed and erased by heating, particularly when a thermal head is used, the surface is heated. Because of the rubbing, the surface is scratched, and if it is severe, there is a problem that a uniform image cannot be formed. The present inventors have proposed that a protective layer be provided on the surface of such a recording medium to reduce scratches on the surface when using a thermal head (JP-A-63-221087, JP-A-63-3210).
17385, JP-A-2-566 and the like). However, it has been difficult to say that simply providing a protective layer on the surface of a conventional recording medium is sufficient when recording / erasing is repeated many times.

On the other hand, in a recording medium of the type in which an organic low-molecular substance is dispersed in a resin base material as described above, if a heating method such as a thermal head for simultaneously applying heat and pressure is used, the number of recordings increases as the number of recordings increases. There is a disadvantage that the particles aggregate and the contrast (white turbidity) is reduced. However, as a means for compensating for such deterioration of the recording medium, a method of heating the reversible thermosensitive layer in a non-contact manner is known. This is because pressure is not applied even if the reversible thermosensitive layer is softened, so that deterioration of the recording medium can be reduced. For example, JP-A-57-82088 discloses a method in which carbon black is contained in a reversible thermosensitive layer or in a layer adjacent to the reversible thermosensitive layer, and recording is performed using a laser beam. According to this proposed method, non-contact recording is possible, but when carbon black is contained in the reversible thermosensitive layer, the entire layer becomes gray and the contrast is significantly reduced. When carbon black is contained in a layer close to the layer, the decrease in contrast does not increase significantly, but the heat conduction of the layer containing carbon black is large, and heat escapes between the layers containing carbon black, so reversible heat sensitivity It has the disadvantage that the temperature of the layer is hard to rise and the sensitivity for recording the image is low, and the image is blurred by the heat transfer in the plane direction.
There is a drawback that image sharpness is poor.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks, to improve the repetition durability, and to form a high-contrast, high-sensitivity, and clear image. An object of the present invention is to provide a thermosensitive recording medium and an image recording method using the same.

[0006]

The first aspect of the present invention is a reversible thermosensitive recording medium, which comprises a heat generating layer, a heat diffusion layer and a reversible thermosensitive layer whose transparency or color tone is reversibly changed by heat on a support. It is characterized in that at least one of the heat generation layer and the heat diffusion layer is divided into recording pixel units. In this reversible thermosensitive recording medium, it is desirable that at least one of the heat generating layer and the heat diffusion layer has a light reflecting function.

The second aspect of the present invention is the same reversible thermosensitive recording medium, which comprises a heat-generating / heat-diffusing layer and a reversible thermosensitive layer whose transparency or color tone is reversibly changed by heat on a support. The heat generation and heat diffusion layer is divided into recording pixel units. Also in this reversible thermosensitive recording material, it is desirable that the heat generation and heat diffusion layer have a light reflecting function.

A third aspect of the present invention is an image recording method using the first or second reversible thermosensitive recording medium, wherein the heat generating layer or the heat generating and heat diffusing layer of the reversible thermosensitive recording medium is irradiated with light. Heat is generated, and the heat is used to form and / or erase an image on the reversible thermosensitive layer.

Hereinafter, the present invention will be described in more detail. FIG. 1 is a schematic view of five examples of the reversible thermosensitive recording medium of the present invention. Among them, (a), (b), (c) and (d) correspond to the first
(E) relates to the second aspect of the present invention. FIG. 1A shows an example in which a heat generating layer 2 is provided on the entire surface of a support 1, a heat diffusion layer 3 divided into recording pixel units is provided thereon, and a reversible thermosensitive layer 4 is further provided thereon. is there. FIG. 1B shows a structure in which a heat diffusion layer 3 divided into recording pixel units is provided on a support 1, a heating layer 2 is provided on the entire surface thereof, and a reversible thermosensitive layer 4 is further provided thereon. is there.
FIG. 1C shows that a heat generating layer 2 'divided into recording pixel units is provided on a support 1, a heat diffusion layer 3' similarly divided into recording pixel units is provided thereon, and a reversible layer is further formed thereon. Thermal layer 4
Is provided. In FIG. 1D, the heat generation layer 2 'and the heat diffusion layer 3 which are divided in units of recording pixels in both cases of FIG. 1C are provided at opposite positions. FIG. 1E shows a structure in which a heat-generating and heat-diffusing layer 5 divided in units of recording pixels is provided on a support 1, and a reversible thermosensitive layer 4 is provided thereon.

FIG. 2 is a diagram for explaining the operation when the thermal diffusion layer 3 is formed by dividing it into recording pixel units. FIG.
(A) uses a reversible thermosensitive recording medium having the configuration shown in FIG. 1 (a), and irradiates a laser beam 25 from a laser light source 24;
A case where light is focused on the heat generation layer 2 by the objective lens 26 is shown. The condensed light heats the heat generating layer 2, and the heat is transmitted to the heat diffusion layer 3 divided and formed in units of recording pixels.
To the reversible thermosensitive layer 4 and heats the reversible thermosensitive layer 4 to form an image. Numeral 10 denotes a heat discoloration part of the reversible heat sensitive part in this case. Such a phenomenon also appears in the reversible thermosensitive recording medium having the configuration shown in FIG.

On the other hand, in the example shown in FIG.
Since the heat diffusion layer 3 is present on the entire surface, the heat generated by the heat generation layer 2 is transmitted through the heat diffusion layer 3, the heat spreads in a plane direction, the temperature of the reversible thermosensitive layer 4 does not rise so much, and the heat discoloration portion 11 is also reversible. Since the heat sensitive layer 4 is formed only in a part of the thickness direction, the image contrast is low.

This tendency is caused by the reversible thermosensitive recording medium (FIG. 1) which is formed separately from the heat / heat diffusion layer 5 and the recording pixel unit.
(E)) and the reversible thermosensitive recording medium (FIGS. 1 (c) and 1 (d)) in which both the heat generating layer 2 'and the thermal diffusion layer 3 are separately formed for each recording image. Appears.

FIG. 3 is a plan view of FIG. FIG.
FIG. 2A shows an example in which a reversible thermosensitive recording medium having the configuration shown in FIG. 1A is used and a laser beam 25 is irradiated as shown in FIG. In the example shown in FIG. 3A, since the thermal diffusion layer 3 is divided into recording pixel units, when a part of the recording pixel unit is irradiated with the laser beam 25, only the area within the thermal diffusion layer 3 is heated. . Further, the laser beam may be irradiated not only at one place in one pixel but also at several places as shown in the lower part of FIG. In the drawing, reference numeral 12 denotes a laser beam irradiation spot, and reference numeral 13 denotes a heated portion.

FIG. 3B shows an example in which the heat diffusion layer 3 and the heat generation layer 2 are present on the entire surface as shown in FIG. 2B.
When the laser beam is irradiated on a part of the portion, the heated portion 13 'spreads over a wide range, and the temperature does not rise so much, and the image becomes bright. Even in the case of this configuration, if the power of the laser beam is increased and the time is shortened, a narrow range can be heated. However, a portion near the center of the heat generating layer 2 becomes unnecessarily high in temperature and the portion is greatly deteriorated. There is a disadvantage that. Further, if it is attempted to form an image by generating heat in the same area as the recording pixel in FIG. 3A in this method, it is necessary to irradiate laser light at several places as shown in FIG. 3C. There is a disadvantage that the position must be controlled with high precision.

In the reversible thermosensitive recording medium of the present invention,
An adhesive layer 6 is provided between the support 1 and the heat generating layer 2 and / or between the heat diffusion layer 3 and the reversible thermosensitive layer 4 for the purpose of improving the adhesiveness.
And / or 6 '(FIG. 4)
(A)). In the reversible thermosensitive recording medium as shown in FIG. 1E, an adhesive layer may be provided between the support 1 or the reversible thermosensitive layer 4 and the heat-generating / thermal diffusion layer 5. In addition, it is also possible to provide an adhesive layer 6 ″ between the heat diffusion layer 3 and the heat generating layer 2 in order to improve the adhesiveness and the like (FIG. 4).
(B)).

Further, in the examples shown in FIGS. 1C and 1D, the heat diffusion layer 3 'and the heat generation layer 2' are shown as having the same size, but one of them is larger. The positions may be shifted from each other as long as at least a part thereof is overlapped. Further, a heat insulating layer 7 can be provided between the support 1 and the heat generating layer 2 or the heat diffusion layer 3 '(or a heat generation and heat diffusion layer) in order to effectively use the heat of the heat generation layer 2. (FIG. 4C). Further, a protective layer 8 may be provided to protect the reversible thermosensitive layer 4 (FIG. 4).
(D)).

Although FIG. 4 does not explain the adhesive layer, the heat insulating layer, and the protective layer only with the reversible thermosensitive recording medium shown in FIG. 1A, FIGS. 1B, 1C, and 1C. The recording medium shown in d) can have the same configuration, and can be used by appropriately combining FIGS. 4A, 4B, 4C, and 4D.

The shape of the pixel is preferably a square, a rectangle, or a circle.
It is preferably from 1 μm to 1 mm, more preferably from 30 μm to 300 μm. The ratio of the pixel area to the entire area is 50% or more.
98% is preferable, and 70% to 95% is more preferable.

The thermal conductivity of the material of each layer is preferably C ₃ ≧ C ₂ , C ₄ , C ₁ C ₅ ≧ C ₄ , C ₁ , and C ₃ ≧ C ₂ ≧ C ₄ , C ₁ More preferably, C ₃ > C ₂ > C ₄ , and C ₁ is the most preferable. Here, C ₁ : thermal conductivity of the support C ₂ : thermal conductivity of the heat generating layer C ₃ : thermal conductivity of the heat diffusing layer C ₄ : thermal conductivity of the reversible thermosensitive layer C ₅ : heat of the heat generating and heat diffusing layer Conductivity. Further, it is preferable that the heat insulating layer has lower thermal conductivity than all other layers.

In the case of a recording medium having the heat diffusion layer 3 and the heat generating layer 2, since the laser light or the like is usually irradiated from the heat generating layer 2 side, the support 1 or the reversible heat sensitive layer 4 on the heat generating layer 2 side is exposed to the light. It is necessary to have a certain degree of transparency. The transmittance is preferably 50% or more, more preferably 70% or more.

The heat generating layer 2 or 2 'has a role of absorbing light and generating heat, and can be roughly classified into inorganic materials and organic materials. Examples of inorganic materials include carbon black, Ge, Bi, In, Te, Se, and Cr.
And the like, and a metal or semimetal and an alloy containing the same, and these are formed into layers by vacuum evaporation or bonding a particulate material with a resin or the like. As the organic material, various dyes can be appropriately used depending on the light wavelength to be absorbed. When a semiconductor laser is used as a light source, a near-infrared absorbing dye having an absorption around 700 to 900 nm is used. Specifically, cyanine dyes, quinone dyes, quinoline derivatives of indnaphthol, phenylenediamine nickel complexes,
And phthalocyanine dyes. The thickness of the heat generating layer 2 or 2 'is preferably about 100 [deg.] To 3 [mu] m.
Å to 2 μm is more preferable.

[0022] It is preferable thermal diffusion layer 3 is thermal conductivity than the upper layer and the lower layer is large, Al, Sn, Zn, Ag ,
Metals such as Au and Cu are preferably used, and these are formed as layers by vacuum deposition or by dispersing these materials into particles and bonding them with a resin or the like. The thickness of the thermal diffusion layer 3 is preferably about 100 ° -μm, more preferably 500 ° -0.5μm.

The heat generation / heat diffusion layer 5 has a function of absorbing light and generating heat and a function of diffusing the generated heat, and functions as a metal or semimetal such as carbon black, Ge, Bi, In, Te, Se, Cr and the like. An alloy containing is preferably used. These are formed as a layer by vacuum deposition or by dispersing these materials into particles and adhering to a resin or the like. The thickness of the heat generation / heat diffusion layer 5 is preferably about 100 ° to 3 μm,
More preferably, the thickness is from 00 to 2 μm.

If the heat diffusion layer 3, the heat generating layers 2, 2 'and the heat and heat diffusion layer 5 in the thermoreversible thermosensitive recording medium of the present invention reflect light regularly, the reversible thermosensitive layer 4 becomes transparent and cloudy. In the case of a material that changes reversibly, there is an advantage that the degree of white turbidity is improved and the contrast is improved.

Glass or a plastic sheet is used for the support, and PET, polycarbonate or the like is used as the plastic sheet.

In addition, the adhesive layers 6, 6 'and 6 "may be anything as long as they have good adhesion to the layers on both sides.
Particularly, a layer mainly composed of resin is desirable. The heat insulating layer 7 is desirably a layer having a gas such as air therein, and is formed of, for example, a hollow filler and a resin. Further, a magnetic storage unit, an information storage unit such as an IC and an optical memory may be provided in the same recording medium.

The "reversible thermosensitive recording material (transparency or color tone reversibly changes depending on temperature)" used in the reversible thermosensitive layer in the present invention reversibly causes a visible change due to a temperature change. Material. The visible change can be divided into a change in color state and a change in shape, and the present invention mainly uses a material that causes a change in color state. Changes in the color state include changes in transmittance, reflectance, absorption wavelength, scattering degree, and the like, and an actual reversible thermosensitive recording material performs display by a combination of these changes. More specifically,
Any material may be used as long as its transparency and color tone are reversibly changed by heat. For example, two or more kinds of polymers are mixed and changed into transparent or cloudy depending on the difference in their compatibility (Japanese Patent Application Laid-Open No. 61-258853). Japanese Patent Application Laid-Open No. 62-66990), a first color state at a first specific temperature higher than normal temperature, and a second color state higher than the first specific temperature. Heating at a second specific temperature, and then cooling to a second color state, and the like. In particular, those in which the color state changes between the first specific temperature and the second specific temperature are preferably used. Examples of these are a transparent state at a first specific temperature and a cloudy state at a second specific temperature (Japanese Patent Application Laid-Open No. 55-154198). One that loses color at a specific temperature (described in Japanese Patent Application No. 2-414438), one that becomes cloudy at a first specific temperature and becomes transparent at a second specific temperature (Japanese Patent Application Laid-Open No. 3-169590). ), One that develops black, red, blue, etc. at a first specific temperature and loses color at a second specific temperature (Japanese Patent Laid-Open No. 2-188293,
JP-A-2-188294).
Among these, the following two materials are particularly typical. Materials that change reversibly between transparent state and cloudy state Materials that change color such as dyes chemically

As a typical example, a reversible heat-sensitive layer in which a low-molecular organic substance such as a higher alcohol or a higher fatty acid is dispersed in a resin base material such as a polyester, as in the prior art and as repeatedly described above, is a typical example. It is listed as. As a typical example, a leuco-based thermosensitive recording material having enhanced reversibility is given.

The reversible heat-sensitive layer of the type that causes a change in the transparency has a resin base material and an organic low-molecular substance dispersed in the resin base material as main components. The reversible thermosensitive recording material here has a temperature range at which it becomes transparent, as described later. The thermoreversible recording medium of the present invention utilizes the change in transparency (transparent state, cloudy opaque state) as described above, and the difference between this transparent state and cloudy opaque state 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 gaps, and there are no voids inside the particles, Light incident from one side is not scattered and transmits to the other side without being scattered.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 at 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 gap and the resin, and is scattered. I have.

In FIG. 5 (representing a change in transparency due to heat), a reversible thermosensitive layer mainly composed of a resin base material and an organic low-molecular substance dispersed in the resin base material is, for example,
At room temperature below T ₀ , it is cloudy and opaque. As you heat it gradually becomes clear from the temperature T _1, the start temperature T ₂ ~
Becomes transparent when heated to T _3, it remains also clear again returned to the normal temperature of T ₀ or less in this state. It begins to resin softening from around the temperature T _1, as the softening proceeds, to reduce the voids in the interface or particles of the resin is contracted resin and an organic low-molecular material particle, increases gradually transparency, temperature T
₂ through T ₃ becomes semi-molten state low-molecular organic material in the remaining becomes transparent by the melted organic low-molecular material fills the void, and crystallized at a relatively high temperature is cooled while remaining seed crystal, in which It is considered that because the resin is still in a softened state, the resin follows a change in the volume of the particles due to crystallization, so that no void is formed and the transparent state is maintained. Upon further heating to T ₄ or higher temperatures, the semi-transparent state in the middle between the maximum transparency and the maximum opacity. Next, when you lower this temperature,
It returns to the original cloudy 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. 5 is only a typical example, and the transparency of each state may change depending on the material by changing the material.

Therefore, by selectively applying heat, the reversible thermosensitive 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. Is possible. If a colored sheet is disposed on the back of such a reversible thermosensitive layer, a color image of the colored sheet on a white background or a white image 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.
Further, when an image of the reversible thermosensitive recording material is used as a reflection image, a contrast can be increased even if the thickness of the reversible thermosensitive layer is reduced by providing a light reflecting layer on the back of the reversible thermosensitive layer. Specifically, Al, Ni, Sn or the like is deposited.

In order to prepare the reversible thermosensitive recording material according to this type of the present invention, generally, (1) a solution in which two components of a resin base material and an organic low-molecular substance are dissolved, or (2) a solution of the resin base material (solvent) A dispersion in which at least one of the organic low-molecular substances is not dissolved) is used.For example, a dispersion in which the organic low-molecular substances are dispersed in fine particles is coated on a support and dried to form a reversible thermosensitive layer. Good.

As the solvent for forming the reversible thermosensitive layer or the thermosensitive recording medium, various types can be selected depending on the type of the resin base material and the organic low molecular weight substance. For example, tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, chloroform,
Examples thereof include carbon tetrachloride, ethanol, toluene, and benzene. The organic low-molecular substance is precipitated as fine particles in the reversible thermosensitive layer obtained when the dispersion is used, as well as when the solution is used, and exists in a dispersed state.

The resin base material used for the reversible thermosensitive layer is a material which forms a layer in which organic low-molecular substances are uniformly dispersed and held, and which affects the transparency at the time of maximum transparency. For this reason, the resin base material is preferably a resin having good transparency, mechanical stability, and good film formability. 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, and vinyl chloride-acrylate copolymer. Copolymers such as vinyl chloride copolymers; polyvinylidene chloride, vinylidene chloride copolymers such as vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer; polyester; polyamide; polyacrylate or polymethacrylate or acrylate -
Methacrylate copolymer; silicone resin and the like. These may be used alone or as a mixture of two or more.

On the other hand, any organic low-molecular substance may be used as long as it changes from polycrystalline to single-crystalline by heat in the recording layer, and generally has a melting point of 30 to 200 ° C., preferably about 50 to 150 ° C. . 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; cycloalkyne; 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; aryl carboxylic acids or their esters, amides or ammonium salts; Their esters, amides or ammonium salts; thioalcohols; thiocarboxylic acids or their esters, amines or ammonium salts; thioalcohols Carboxylic acid esters, and the like. These may be used alone or in combination of two or more. The carbon number of these compounds is 10 to 60, preferably 10 to 38, particularly preferably 10 to 30. The alcohol group in the ester may be saturated or unsaturated, and may be halogen-substituted. In any case, the organic low molecular weight substance contains at least one kind of oxygen, nitrogen, sulfur and halogen in the molecule, for example, -OH, -COOH, -CONH-, -COO
_{R, -NH -, - NH 2} , -S -, - SS -, - O-, is preferably a compound containing a halogen and the like.

More specifically, these compounds include
Uric acid, dodecanoic acid, myristic acid, pentadecane
Acid, palmitic acid, stearic acid, behenic acid, nonadeca
Higher fatty acids such as acid, araginic and oleic acid; stearic acid
Methyl phosphate, tetradecyl stearate, stearin
Octadecyl acid, octadecyl laurate, palmitin
Of higher fatty acids such as tetradecyl acrylate and dodecyl behenate
Stele; And ether or thioether. In particular, the present invention
Higher fatty acids, especially palmitic acid, stearic acid,
Higher fatty acids having 16 or more carbon atoms such as henic acid and lignoceric acid
Are preferred, and higher fatty acids having 16 to 24 carbon atoms are more preferred.
No.

In order to widen the range of temperatures at which transparency can be obtained, the organic low-molecular substance described in this specification may be appropriately combined, or such an organic low-molecular substance may be combined with another material having a different melting point. . These are disclosed, for example, in JP-A-63-3
No. 9378, JP-A-63-130380 and Japanese Patent Application No. 63-14
No. 754, Japanese Patent Application No. 1-140109, and the like, but are not limited thereto. The ratio between the organic low-molecular substance and the resin base material in the reversible thermosensitive layer is preferably about 2: 1 to 1:16, and more preferably 1: 2 to 1: 8 by weight. When the ratio of the resin base material is less than this, it becomes difficult to form a film holding the organic low-molecular substance in the resin base material. Becomes difficult.

In addition to the above-mentioned components, additives such as a surfactant and a high-boiling solvent can be added to the reversible thermosensitive layer in order to facilitate formation of a transparent image. Specific examples of these additives are as follows. Examples of high boiling solvents: tributyl phosphate, tri-2-ethylhexyl phosphate, triphenyl phosphate, tricresyl phosphate, butyl oleate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, diphthalic phthalate -n-octyl, di-2-ethylhexyl phthalate, diisononyl phthalate, dioctyldecyl phthalate, diisodecyl phthalate, butylbenzyl phthalate, dibutyl adipate, di-n-hexyl adipate, di-adipate
2-ethylhexyl, 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.

Examples of surfactants and other additives; polyhydric alcohol higher fatty acid esters; polyhydric alcohol higher alkyl ethers; polyhydric alcohol higher fatty acid esters, higher alcohols, higher alkyl phenols, higher fatty acid higher alkyl amines, higher fatty acid amides Lower olefin oxide adducts of fats and oils or polypropylene glycol; acetylene glycol; Na, Ca, Ba or Mg salts of higher alkylbenzene sulfonic acids; higher fatty acids, aromatic carboxylic acids, higher fatty acid sulfonic acids, aromatic sulfonic acids, sulfuric acid monoesters Or phosphoric acid 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;
Olefin-maleic anhydride copolymer. Further, the reversible thermosensitive phase may be cross-linked by heat, UV, EB, or the like, thereby making it possible to repeatedly improve durability. Among them, crosslinking by EB is preferable.

As described above, the protective layer 8 can be provided on the reversible thermosensitive layer 4 to protect the reversible thermosensitive layer. Examples of the material for the protective layer (thickness: 0.1 to 5 μm) include silicone rubber, silicone resin (described in JP-A-63-221087), and polysiloxane graft polymer (Japanese Patent Application No. 62-15255).
No. 0) or UV curable resin or electron beam curable resin
(Described in the specification of Japanese Patent Application No. 63-310600). In any case, a solvent is used at the time of application, but the solvent is
It is desirable that the resin of the heat-sensitive layer and the organic low-molecular substance are hardly dissolved. Examples of the solvent that hardly dissolves the resin and the organic low-molecular substance in the reversible thermosensitive layer include n-hexane, methyl alcohol, ethyl alcohol, and isopropyl alcohol, and an alcohol-based solvent is particularly desirable from the viewpoint of cost.

Further, an intermediate layer can be provided between the protective layer and the reversible thermosensitive layer in order to protect the reversible thermosensitive layer from the solvent and the monomer component of the protective layer forming solution. As the material of the intermediate layer, the following thermosetting resins and thermoplastic resins can be used in addition to those listed as the resin base material in the thermosensitive layer. That is, 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 middle layer is 0.1-2
About μm is preferable.

Next, the reversible thermosensitive layer formed of a reversible thermochromic composition utilizing a color reaction between an electron-donating color-forming compound and an electron-accepting compound will be described. . A thermochromic composition utilizing a color-forming reaction between an electron-donating color-forming compound and an electron-accepting compound, when the electron-donating color-forming compound and the electron-accepting compound are melted by heating. Produces an amorphous color former,
On the other hand, it utilizes the phenomenon that when the amorphous color former is heated at a temperature lower than the melting temperature, the electron accepting compound undergoes crystallization and the color former disappears.

The thermochromic composition develops color instantaneously by heating, and its coloration state exists stably even at room temperature. On the other hand, the composition in the coloration state is instantaneously heated by heating below the coloration temperature. The color is erased, and the erased state is stably present even at room temperature, and such a reversible peculiar coloring / erasing behavior is a novel and surprising phenomenon that has not been seen before.

FIG. 6 shows the principle of color development and decoloration when this composition is used as a heat-sensitive recording medium, that is, image formation and image erasure.
This will be described with reference to the graph shown in FIG. The vertical axis of the graph represents the color density, the horizontal axis represents the temperature, the solid line represents the image forming process by heating, and the broken line represents the image erasing process by heating. A is the concentration in a fully erased state, B is the concentration in the complete colored state when heated to T ₆ above temperature, C is the concentration in the T ₅ temperature below the full colored state, D is T ₅ shows the concentration when heated and erased with a temperature between through T _6.

[0045] The compositions according to the present invention, in the T ₅ temperature below in colorless state (A). Recording the performing (image formation) forms a recorded image by color (B) by heating to T ₆ or more temperature by such as a thermal head. The recorded image is also returned to T ₅ temperature below according solid 51, is not lost memory of the recording holds the intact (C).

Next, in order to erase the recorded image, the formed recorded image is heated to a temperature between T _{5 and} T ₆ lower than the color development temperature to be in a colorless state (D). This state be returned to T ₅ temperature below holds intact colorless state (A). That is, the process of forming the recorded image reaches C along the path indicated by the solid line ABC, and the recording is held. Next, in the process of erasing the recorded image, the process proceeds to A along the path indicated by the broken line CDA, and the erased state is maintained. The behavior characteristics of forming and erasing the recorded image are reversible and can be repeated many times.

The reversible thermochromic composition contains a color former and a developer as essential components. A color-forming state is formed by heating and melting the color-forming agent and the developer, while the color-forming state is erased by heating at a temperature lower than the color-forming temperature, and the color-forming state and the decolored state are stably present at room temperature. It is. As described above, the mechanism of such coloring and decoloring in the composition is as follows.When the coloring agent and the developing agent are heated and melted and mixed at the coloring temperature, the composition becomes amorphous and the coloring state is formed. On the other hand, when heated at a temperature lower than the coloring temperature, the developer of the colored composition undergoes crystallization to form an erased state of coloring. However, by heat-sensitive layer the process of decolorizing was heated to T ₆ or more temperature is taken also in this case, the particles of color former and the developer is returned to the original, to form a new colored state Is advantageous.

A composition comprising an ordinary color former and a developer, for example, a leuco compound having a lactone ring, which is a dye precursor widely used in conventional thermal recording paper, and a phenolic compound exhibiting a color developing effect. When this is melted and mixed by heating, a color development state based on ring opening of the lactone ring of the leuco compound is obtained. This colored state is an amorphous state in which both are compatible. This colored amorphous state exists stably at room temperature, but does not crystallize when heated again, and there is no separation of the phenolic compound from the leuco compound, so there is no ring closure of the lactone ring and decolorization. Do not.

On the other hand, when the composition of the color former and the color developer according to the present invention is melted and mixed by heating, it becomes a colored state, exhibits an amorphous state as in the conventional case, and is stable at room temperature. Exists. However, in the case of the present invention, when the color-formed amorphous composition is heated at a temperature lower than the color-forming temperature, that is, at a temperature that does not reach the molten state, crystallization of the color developer occurs, and the composition is compatible with the color-forming agent. The bond due to the state cannot be maintained, and the color developer is separated from the color former. It is considered that due to the separation of the color developer from the color developer due to crystallization, the color developer cannot accept electrons from the color developer and the color developer loses its color.

The above-mentioned specific coloring / decoloring behavior observed in the thermochromic composition is based on the mutual solubility of the coloring agent and the coloring agent by heating and melting, the strength of the action of both in the coloring state, and the coloring agent. Is related to the solubility of the color former, the crystallinity of the developer, etc.
In principle, it becomes amorphous by heating and melting, while
Any color former / color developer system that causes crystallization by heating at a temperature lower than the color development temperature can be used as a composition component in the present invention. Furthermore, since those having such characteristics show endothermic changes due to melting and exothermic changes due to crystallization in thermal analysis, the color former / developer system applicable to the present invention can be easily analyzed by thermal analysis. You can check. In addition, the reversible thermochromic composition system according to the present invention may include a third substance, for example, the reversible decoloring behavior is maintained even when a polymer substance is present. Was confirmed. In the thermochromic composition of the present invention, the decoloration is caused by separation from the color former due to crystallization of the color developer. is important.

Next, examples of the developer preferably used in the present invention are as follows. As described above, the developer applicable to the present invention can be easily found by thermal analysis. However, the present invention is not limited to this. (1) An organic phosphoric acid compound represented by the following general formula (1): R ₁ -PO (OH) ₂ (1) (where R ₁ is a linear or branched alkyl group or alkenyl having 8 to 30 carbon atoms) Specific examples of the organic phosphoric acid compound include the following. Octylphosphonic acid, nonylphosphonic acid, decylphosphonic acid, dodecylphosphonic acid, tetradecylphosphonic acid, hexadecylphosphonic acid, octadecylphosphonic acid, eicosylphosphonic acid, docosylphosphonic acid, tetracosylphosphonic acid.

(2) Organic acid having a hydroxyl group at the α-position carbon represented by the following general formula (2): R ₂ —CH (OH) COOH (2) (where R ₂ is a straight chain having 6 to 28 carbon atoms) Specific examples of the organic acid having a hydroxyl group at the carbon at the α-position include the following. α-hydroxyoctanoic acid,
α-hydroxydodecanoic acid, α-hydroxytetradecanoic acid, α-hydroxyhexadecanoic acid, α-hydroxyoctadecanoic acid, α-hydroxypentadecanoic acid, α-hydroxyeicosanoic Acid, α-hydroxydocosanoic acid and the like.

The color former used here is a compound having an electron-accepting property, and is itself a colorless or light-colored dye precursor, and is not particularly limited.
Triphenylmethanephthalide compounds, fluoran compounds, phenothiazine compounds, leuco auramine compounds, rhodamine lactam compounds, spiropyran compounds, indolinophthalide compounds, and the like, and specific examples include the following: Can be 3,3-bis (p
-Dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone),
3,3-bis (p-dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7
-Methylfluoran, 3-diethylamino-7,8-benzfluoran, 3-diethylamino-6-methyl-7
-Chlorofluorane, 3- (Np-tolyl-N-ethylamino) -6-methyl-7-anilinofluoran, 3
-Pyrrolidino-6-methyl-7-anilinofluoran,
2- {N- (3'-trifluoromethylphenyl) amino} -6-diethylaminofluoran, 2- {3,6-
Bis (diethylamino) -6- (o-chloroanilino)
Lactam xanthylbenzoate {3-diethylamino-
6-methyl-7- (m-trichloromethylanilino) fluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-dibutylamino-7- (o-chloroanilino) fluoran, 3-N-methyl-N -Amylamino-6-methyl-7-anilinofluoran, 3-
N-methyl-N-cyclohexylamino-6-methyl-
7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) fluoran, benzo Leucomethylene blue, 6 '
-Chloro-8'-methoxy-benzoindolino-spiropyran, 6'-bromo-2'-methoxy-benzoindolino-spiropyran, 3- (2'-hydroxy-4'-
Dimethylaminophenyl) -3- (2'methoxy-5 '
-Chlorophenyl) phthalide, 3- (2'hydroxy-
4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl) phthalide, 3- (2'-hydroxy-4'-diethylaminophenyl) -3-
(2'-methoxy-5'-methylphenyl) phthalide,
3- (2'-methoxy-4'-dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-
Methoxyphenyl) phthalide, 3-morpholino-7-
(N-propyl-trifluoromethylaniline) fluoran, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethylanilino) fluoran, 3
-Pyrrolidino-7- (di-p-chlorophenyl) methylaminofluoran, 3-diethylamino-5-chloro-
7- (α-phenylethylamino) fluoran, 3-
(N-ethyl-p-toluidino) -7- (α-phenylethylamino) fluoran, 3-diethylamino-7-
(O-methoxycarbonylphenylamino) fluoran, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluoran, 3-diethylamino-
7-piperidinofluoran, 2-chloro-3- (N-methoxytoluidino) -7- (pn-butylanilino)
Fluoran, 3- (N-methyl-N-isopropylamino) -6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran,
3,6-bis (dimethylamino) fluorenespiro (9,3 ')-6'-dimethylaminophthalide, 3-
(N-benzyl-N-cyclohexylamino) -5,6
-Benzo-7-α-naphthylamino-4'-bromofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-N-ethyl-N- (2-ethoxypropyl) amino-6 Methyl-7-anilinofluoran, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-mesitidino-4 ', 5' −
Benzofluoran, 3-N-methyl-N-isobutyl-
6-methyl-7-anilinofluoran, 3-N-ethyl-N-isoamyl-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7- (2 ',
4'-dimethylanilino) fluoran and the like.

Particularly preferred color formers used in the present invention are those containing halogen as a substituent. Examples of such a device include the following. 3,3-bis (p-dimethylaminophenyl) -6
-Chlorophthalide, 3-cyclohexylamino-6-chlorofluorane, 3-cyclohexylamino-6-bromofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-bromofluoran, 3
-Dipropylamino-7-chlorofluoran, 3-diethylamino-6-chloro-7-phenylamino-fluoran, 3-pyrrolidino-6-chloro-7-phenylamino-fluoran, 3-diethylamino-6-chloro-7
-(M-trifluoromethylphenyl) amino-fluoran, 3-cyclohexylamino-6-chloro-7- (o
-Chlorophenyl) amino-fluoran, 3-diethylamino-6-chloro-7- (2 ', 3'-dichlorophenyl) amino-fluoran, 3-diethylamino-6-
Methyl-7-chlorofluoran, 3-dibutylamino-
6-chloro-7-ethoxyethylamino-fluoran,
3-diethylamino-7- (o-chlorophenyl) amino-fluoran, 3-diethylamino-7- (o-bromophenyl) amino-fluoran, 3-diethylamino-7- (o-chlorophenyl) amino-fluoran, 3
-Dibutylamino-7- (o-fluorophenyl) amino-fluoran, 6'-bromo-3'-methoxybenzoindolino-pyrrospirane, 3- (2'-methoxy-
4'-dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-chlorophenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2 '-Methoxy-5'-chlorophenyl) phthalide, 2- {3,6-bis (diethylamino)}-9- (o-chlorophenyl) amino-xanthyl benzoate lactam and the like.

A preferred color former when used in the present invention is a compound represented by the following general formula (3).

Embedded image (Provided that R ₃ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ₄ is a hydrogen atom or an amino group which may be substituted, X is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a phenylamino group. , M is an integer of 1 or 2, Y is a carbon number of 1-4.
An alkyl group or an alkoxy group having 1 to 2 carbon atoms, n is 1
Or an integer of 2. )

Specific examples of the compound represented by the general formula (3) include the following. 3-
(N-methyl-N-phenylamino) -7-amino-fluoran, 3- (N-ethyl-N-phenylamino)-
7-amino-fluoran, 3- (N-propyl-N-phenylamino) -7-amino-fluoran, 3- {N-
Methyl-N- (p-methylphenyl) amino} -7-amino-fluoran, 3- {N-ethyl-N- (p-methylphenyl) amino} -7-amino-fluoran, 3-
{N-propyl-N- (p-methylphenyl) amino}
-7-amino-fluoran, 3- {N-methyl-N-
(P-ethylphenyl) amino} -7-amino-fluoran, 3- {N-ethyl-N- (p-ethylphenyl)
Amino} -7-amino-fluorane, 3- {N-propyl-N- (p-ethylphenyl) amino} -7-amino-fluoran, 3- {N-methyl-N- (2 ′, 4′-dimethyl) Phenyl) amino} -7-amino-fluoran,
3- {N-ethyl-N- (2 ', 4'-dimethylphenyl) amino} -7-amino-fluoran, 3- {N-propyl-N- (2', 4'-dimethylphenyl) amino}
-7-amino-fluoran, 3- {N-methyl-N-
(P-chlorophenyl) amino} -7-amino-fluoran, 3- {N-ethyl-N- (p-chlorophenyl)
Amino} -7-amino-fluoran, 3- {N-propyl-N- (p-chlorophenyl) amino} -7-amino-fluoran, 3- (N-methyl-N-phenylamino) -7-methylamino -Fluoran, 3- (N-ethyl-N-phenylamino) -7-methylamino-fluoran, 3- (N-propyl-N-phenylamino) -7-
Methylamino-fluoran, 3- {N-methyl-N-
(P-methylphenyl) amino} -7-ethylamino-
Fluoran, 3- {N-ethyl-N- (p-methylphenyl) amino} -7-benzylamino-fluoran, 3
-{N-methyl-N- (2 ', 4'-dimethylphenyl)
Amino} -7-methylamino-fluoran, 3- {N-
Ethyl-N- (2 ′, 4′-dimethylphenyl) amino
-7-ethylamino-fluoran, 3- {N-methyl-
N- (2 ', 4'-dimethylphenyl) amino} -7-benzylamino-fluoran, 3- {N-ethyl-N-
(2 ′, 4′-dimethylphenyl) amino} -7-benzylamino-fluoran, 3- (N-methyl-N-phenylamino) -7-dimethylamino-fluoran, 3- (N
-Ethyl-N-phenylamino) -7-dimethylamino-fluoran, 3- {N-methyl-N- (p-methylphenyl) amino} -7-diethylamino-fluoran,
3- {N-ethyl-N- (p-methylphenyl) amino} -7-diethylamino-fluoran, 3- (N-methyl-N-phenylamino) -7-dipropylaminofluoran, 3- (N- Ethyl-N-phenylamino) -7
-Dipropylaminofluoran, 3- {N-methyl-N
-(P-methylphenyl) amino} -7-dibenzylamino-fluoran, 3- {N-ethyl-N- (p-methylphenyl) amino} -7-dibenzylamino-fluoran, 3- {N-ethyl -N- (p-methylphenyl)
Amino} -7-di (p-methylbenzyl) amino-fluoran, 3- {N-methyl-N- (p-methylphenyl) amino} -7-acetylamino-fluoran, 3-
{N-ethyl-N- (p-methylphenyl) amino}-
7-benzoylamino-fluoran, 3- {N-methyl-N- (p-methylphenyl) amino} -7- (o-methoxybenzoyl) amino-fluoran, 3- {N-ethyl-N- (p-methyl Phenyl) amino} -6-methyl-7-phenylamino-fluoran, 3- {N-methyl-N- (p-methylphenyl) amino} -6-methyl-7-phenylamino-fluoran, 3- {N- Methyl-N- (p-methylphenyl) amino} -6-tert
-Butyl-7- (p-methylphenyl) amino-fluoran, 3- (N-ethyl-N-phenylamino) -6
Methyl-7- (N-ethyl-N- (p-methylphenyl) amino-fluoran, 3- {N-propyl-N-
(P-methylphenyl) amino} -6-methyl-7-
{N-methyl-N- (p-methylphenyl) amino}-
Fluoran, 3- {N-ethyl-N- (p-methylphenyl) amino} -5-methyl-7-benzylamino-fluoran, 3- {N-ethyl-N- (p-methylphenyl) amino} -5 -Chloro-7-dibenzylamino-fluoran, 3- {N-methyl-N- (p-methylphenyl) amino} -5-methoxy-7-dibenzylamino-
Fluoran, 3- {N-ethyl-N- (p-methylphenyl) amino} -6-methyl-fluoran, 3- {N-
Ethyl-N- (p-methylphenyl) amino} -5-methoxy-fluoran and the like.

The developers are used alone or in combination of two or more. Similarly, the color former can be applied alone or in combination of two or more. The thermochromic composition can be formed as a reversible thermosensitive layer on a support and used as a reversible thermosensitive recording medium. In this case, the reversible thermosensitive layer is obtained by uniformly dispersing or dissolving a color former and a developer together with a binder with water or an organic solvent according to a conventionally known method, and applying the resultant to a substrate.

As the binder, various conventional binders can be appropriately used. For example, polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, methoxy cellulose, carboxymethyl cellulose, methyl cellulose, cellulose acetate, gelatin, casein, starch, polyacrylic acid Soda, polyvinylpyrrolidone, polyacrylamide, maleic acid copolymer, acrylic acid copolymer, polystyrene, polyvinyl chloride, polyvinyl acetate, polyacrylic esters, polymethacrylic esters, vinyl chloride-vinyl acetate copolymer Coalesce, styrene copolymer, polyester,
There are polyurethane and the like.

In the present invention, various additives, such as dispersants, surfactants, fillers, and the like, which are used in ordinary thermosensitive recording paper, are used for the purpose of improving the coating properties or recording properties as required.
A color image stabilizer, an antioxidant, a light stabilizer, a lubricant and the like can be added. Further, as described above, a protective layer and an intermediate layer may be provided as necessary.

In the reversible thermosensitive recording medium of the present invention,
It may be long, endless, or even card-shaped.

[0061]

Next, the present invention will be described more specifically with reference to examples. All parts here are by weight.

Example 1 Carbon black 20 parts Vinyl chloride-vinyl acetate-vinyl alcohol copolymer 4 parts (UCC: VAGH) on a transparent polyester film (Lumirror T-60, manufactured by Toray Industries) having a thickness of about 100 μm. A liquid consisting of 4 parts Coronate L (10% toluene solution) 4 parts Methyl ethyl ketone 36 parts Toluene 36 parts was applied by a wire bar and dried by heating to form a heat generating layer having a thickness of about 1.0 μm.

Next, this was left in an environment of 50 ° C. for 24 hours to cure the heat generating layer.
Approximately 2,000 mm in a square shape of 90 μm on a side at 0 μm intervals
A thermal diffusion layer divided into recording pixel units was formed by vacuum evaporation with a thickness.

Further, a solution consisting of 10 parts of vinyl chloride-vinyl acetate-phosphate ester copolymer (Denka vinyl # 1000P, manufactured by Denki Kagaku Kogyo Co., Ltd.) 45 parts of methyl ethyl ketone 45 parts of toluene was applied by a wire van and heated. After drying, an adhesive layer having a thickness of about 1.0 μm was formed.

Further, 5 parts of behenic acid (manufactured by NOF Corporation: NAA-22S) 5 parts of eicosane diacid (manufactured by Okamura Oil Co., Ltd .: SL-20-99) 5 parts of vinyl chloride-vinyl acetate copolymer 40 parts ( A solution consisting of 200 parts of THF and 20 parts of toluene was applied with a wire bar and dried by heating to form a reversible thermosensitive layer having a thickness of about 10 μm.

Further, a solution consisting of 10 parts of 75% urethane acrylate ultraviolet curable resin and 10 parts of butyl acetate solution (manufactured by Dainippon Ink and Chemicals, Inc .: Unidick C7-157) was applied by a wire bar using 10 parts of isopropyl alcohol. 80 after heating and drying
Ultraviolet light was irradiated from a w / cm ultraviolet lamp and cured to provide a protective layer having a thickness of about 3 μm, thereby producing a thermoreversible recording medium.

Using this thermoreversible recording medium, an image was recorded by a laser recording apparatus. 8 shows a schematic configuration of the laser recording device shown in FIG. The recording device is a semiconductor laser (Laser
Diode) as a light source, an optical head unit equipped with a laser beam irradiation optical system, a recording unit that performs main scanning by rotating the drum, and a sub-scanning unit that moves the recording optical head by a microstage, and is composed of three elements. The operation of the semiconductor laser, the rotation of the drum, and the movement of the microstage based on the recording signal are controlled by a microcomputer. As a light source, a single fundamental mode semiconductor laser having a maximum continuous oscillation output of 100 mW (SDL703 manufactured by Sanyo Electric Co., Ltd.)
2: oscillation wavelength 830 nm). The light spot diameter in this device is about 3 μm.

The laser output was set to 40 mW, and the period was 150 μm.
A pulse of 120 μm was applied from the side of the support in seconds, and laser irradiation was performed at four places per pixel as shown in the lower part of FIG. 3A. As a result, the portion corresponding to the position of the pixel almost changed to dark opacity.

Example 2 On a white polyester film (Lumilar E-20, manufactured by Toray Industries Co., Ltd.) having a thickness of about 100 μm, a 75% urethane acrylate ultraviolet curable resin 10 parts butyl acetate solution (manufactured by Dainippon Ink and Chemicals, Inc .: Uni Dick C7-164) Apply a solution consisting of 10 parts of MEK with a wire bar, and heat and dry.
It was cured with a W / cm ultraviolet lamp to provide an adhesive layer of about 2 μm. Al was vacuum-deposited thereon using the same mask as in Example 1 to provide a square heat diffusion layer having a side of about 90 μm. Further, a phthalocyanine dye was vacuum-deposited thereon at a position substantially the same as that of the thermal diffusion layer using a mask. Further, a reversible thermosensitive layer and a protective layer were laminated thereon in the same manner as in Example 1 to prepare a reversible thermosensitive recording medium. Using this reversible thermosensitive recording medium, an image was formed in the same manner as in Example 1 except that a laser beam was irradiated from the protective layer side. As a result, the portion corresponding to the position of the pixel showed a dark turbid change.

Example 3 Germanium was coated on a transparent polyester film having a thickness of about 50 μm by using a mask in the same manner as in Example 1, and a side of about 90 μm was used.
A heat-generating and heat-diffusing element composed of square pixels was formed. Further, an adhesive layer, a reversible thermosensitive layer, and a protective layer were formed thereon in the same manner as in Example 1 to prepare a reversible thermosensitive recording medium.
When an image was formed using this reversible thermosensitive recording medium in the same manner as in Example 1, the portion corresponding to the position of the pixel substantially changed to a white turbidity.

[0071]

According to the reversible thermosensitive recording medium of the present invention, a heating layer and / or a heat diffusion layer or a heat / heat diffusion layer is formed for each pixel. A high-sensitivity, clear image could be formed, and high-definition device control became unnecessary.

[Brief description of the drawings]

1 (a), (b), (c), (d) and (e) are schematic views of five examples of the reversible thermosensitive recording medium of the present invention.

FIG. 2 is a diagram showing a state when recording is performed on one of the reversible thermosensitive recording media of the present invention, in comparison with that for comparison.

FIG. 3A is a diagram showing a state when recording is performed on one of the reversible thermosensitive recording media of the present invention, and FIGS.
Is a diagram for comparison.

FIGS. 4 (a), (b), (c) and (d) are schematic views of four other examples of the reversible thermosensitive recording medium of the present invention.

FIG. 5 is a diagram illustrating characteristics of a reversible thermosensitive layer in the reversible thermosensitive recording medium of the present invention.

FIG. 6 is a view for explaining characteristics of a reversible thermosensitive layer in another reversible thermosensitive recording medium of the present invention.

FIG. 7 is a diagram schematically illustrating an example of a laser recording apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support 2, 2 Heat generation layer 3 Heat diffusion layer 4 Reversible heat-sensitive layer 5 Heat generation and heat diffusion layer 6, 6 ', 6 "Adhesive layer 7 Heat insulation layer 8 Protective layer 10, 11 Heat discoloration part 12 Laser irradiation spot 13, 13 ′ Heating part 24 Laser light source 25 Laser light 26 Objective lens

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Takashi Kitamura 2-18-36 Haraki, Ichikawa-shi, Chiba (56) References JP-A-63-253393 (JP, A) JP-A-5-181423 (JP, A JP-A-4-76831 (JP, A) JP-A-5-124360 (JP, A) JP-A-61-42675 (JP, A) JP-A-4-29883 (JP, A) 278332 (JP, A) JP-A-5-169800 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/26-5/36

Claims (5)

(57) [Claims] 1. A method of absorbing light irradiated on a support and generating heat.
(Hereinafter referred to as a heating layer), a heat diffusion layer, and a reversible heat-sensitive layer whose transparency or color tone changes reversibly by heat, wherein at least one of the heat generation layer and the heat diffusion layer is formed.
In both cases, the thermal diffusion layer is divided into recording pixel units, and
A reversible thermosensitive recording medium, wherein the size of the elementary unit is larger than the diameter of the irradiated light . 2. The apparatus according to claim 1, wherein at least one of the heat generating layer and the heat diffusion layer has a light reflecting function.
The reversible thermosensitive recording medium according to the above. 3. The support body absorbs the irradiated light and generates heat.
Transparency or color tone by heat generation and the thermal diffusion layer and heat to the be one obtained by laminating the reversible thermosensitive layer reversibly changes,
The heat / heat diffusion layer is divided into recording pixel units , and
A reversible thermosensitive recording material characterized in that the recording pixel unit size is larger than the irradiated light diameter . 4. The reversible thermosensitive recording medium according to claim 3, wherein said heat generation and heat diffusion layer has a light reflecting function. 5. A sports to the heating layer or heating and the thermal diffusion layer of the reversible thermosensitive recording medium according to any one of claims 1 to 4
An image recording method, comprising: irradiating a cut light to generate heat; and using the heat to form and / or erase an image on the reversible thermosensitive layer.