JP2000043428A - Reversible thermosensitive recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reversible thermosensitive recording sheet having excellent water resistance and corrosion resistance as the sheet having a light reflecting layer scarcely damaged or contaminated. SOLUTION: A recording layer 3 made of a reversible thermosensitive recording material for displaying or erasing a visible image by reversibly changing in transparency according to a temperature is provided. A light transmission synthetic resin film 1 made of a polyethylene terephthalate or the like is provided at one side surface of the layer 3. A laminate having a light reflecting layer 2 made of a metal of a reflecting material provided by superposing an aluminum vapor deposited layer or the like on the film 1 is provided.

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 sheet capable of displaying and erasing a visible image depending on temperature, and more particularly, to a commuter pass, an entrance permit, various prepaid cards and other cards, and an OHP sheet. It relates to a reversible thermosensitive recording sheet that can be made.

[0002]

2. Description of the Related Art In general, a commuter pass used by a user of a transportation system, an admission permit to an event hall or a predetermined building, and other repeatedly used cards are written on the surface by characters such as characters printed by an administrator. The device is checked with the naked eye or magnetically recorded information recorded on cards is read by a device to prevent unauthorized use.

However, if the contents written on the surface of the cards do not match the magnetically recorded information, the administrator cannot immediately judge the correctness of the information only on the front surface, and the reading device of the magnetic recording is erroneous. In some cases, it was difficult to completely prevent unauthorized use of cards and the like.

[0004] Further, even with a magnetic recording card such as a prepaid card or an IC card provided with an IC chip, information recorded on the card, such as a past payment amount or a balance, cannot be visually confirmed every time the card is used. Therefore, both the administrator and the user were inconvenient.

In order to solve such inconveniences, reversible thermosensitive recording sheets displaying recognizable recording information by a reversible thermosensitive recording layer (JP-A-54-19377, JP-A-55-19737). 154198).

In this reversible thermosensitive recording sheet, a recording material in which a crystalline organic low-molecular substance is dispersed in a polymer resin base material is provided in a layer form, and this recording material is heated to a specific temperature region (T1). A transparent image and a step of heating the region (T2) higher than the specific temperature region to make the region cloudy by selectively heating the region (T2). Display or erase.

As shown in FIG. 4, a thermosensitive recording material layer 10 of a conventional reversible thermosensitive recording sheet B is provided on a plastic film 11 in order to improve the visibility of a displayed image. , Usually the thermosensitive recording material layer 10
Light-reflective metal (A) between
1, Ni, Sn, etc.).

When the light reflecting layer is provided on the back side of the heat-sensitive recording material layer, the image on the front of the reversible heat-sensitive recording sheet is such that the light reflecting layer immediately below the transparent portion of the heat-sensitive recording material layer reflects visible light to form a metal. Color (silver), the opaque (white turbid) portion of the heat-sensitive recording material layer becomes a white image, and the contrast between the silver color of the transparent portion and the white color of the opaque portion improves the visibility of the image.

[0009]

However, the above-mentioned conventional reversible thermosensitive recording sheet is obtained by directly coating a thermosensitive recording material on a light reflecting layer composed of a metal deposition film formed on a sheet substrate. In addition, there is a problem that the metal vapor-deposited film is easily damaged and stained in the process of providing the heat-sensitive recording material layer in an overlapping manner or in the process of temporarily winding and storing the heat-sensitive recording material before coating. The heat-sensitive recording material layer in contact with such a scratched or stained metal vapor-deposited film has reduced durability and is liable to peel off, and the reversible thermosensitive recording sheet has the surface state of the metal vapor-deposited film as it is. Since it appears as an image, scratches and dirt on the metal deposition film may impair the appearance of the product.

A conventional reversible thermosensitive recording sheet provided with a light reflecting layer superimposed on a thermosensitive recording material layer may cause corrosion of a metal vapor deposited layer when immersed in water or stored for a long time in a high humidity atmosphere. However, there is also a problem that it often peels off.

[0011] Such corrosion occurs more remarkably than when the metal deposition layer is alone exposed to water. It is presumed that, for example, hydrochloric acid, which is a decomposition product of the system resin, permeates the light reflecting layer and corrodes the metal deposition film.

As a method of forming a heat-sensitive recording material layer on a metal vapor deposited layer of a reversible heat-sensitive recording sheet, a method of applying a material diluted with a very soluble solvent such as tetrahydrofuran is usually employed. However, there is also a problem that a solvent having high solubility corrodes the light reflection layer formed of the metal deposition film at the time of this coating.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a reversible thermosensitive recording sheet in which a light reflecting layer made of a metal vapor-deposited film is hardly damaged or stained in a production stage.
Another object of the present invention is to provide a reversible thermosensitive recording sheet excellent in water resistance, so that the metal deposited film does not corrode or peel off even when immersed in water or stored for a long time in an atmosphere of high humidity. .

[0014]

In order to solve the above problems, the present invention comprises a recording layer made of a reversible thermosensitive recording material and a light reflection layer, and the light reflection layer is provided between these two layers. This was a reversible thermosensitive recording sheet comprising a laminate provided with a protective protective layer. Also, a recording layer made of a reversible thermosensitive recording material capable of displaying and erasing a visible image by changing the transparency reversibly with temperature,
Since a light-transmitting synthetic resin layer is provided on one surface side of the recording layer, and a reversible thermosensitive recording sheet including a light-reflective layer using a metal as a reflective material is provided on the synthetic resin layer. is there.

In the above-mentioned reversible thermosensitive recording sheet, polyethylene terephthalate can be used as a synthetic resin for forming the protective layer or the light-transmitting synthetic resin layer. A light reflection layer in which a chromium vapor deposition layer or a silicone metal vapor deposition layer is laminated on the substrate can be employed.

In the reversible thermosensitive recording sheet of the present invention, a light reflecting layer made of a metal as a reflecting material is provided on one side of the recording layer via a protective layer made of a synthetic resin layer or the like. Protected from physical impact and dirt from the side. Since the synthetic resin layer is a light-transmitting synthetic resin, the visibility of the image of the reversible thermosensitive recording material is not hindered.

Since the light reflecting layer is not in direct contact with the recording layer via a light-transmitting synthetic resin layer between the light reflecting layer and the recording layer made of a reversible thermosensitive recording material, it has a very high solubility such as tetrahydrofuran. Even if a reversible thermosensitive recording material diluted with a solvent and coated is used, the light reflecting layer made of a metal as a reflecting material and made of a metal deposited film or the like does not corrode with the solvent.

In the reversible thermosensitive recording sheet of the present invention, the waterproofness is enhanced by the synthetic resin layer, and the water vapor that has permeated from the recording layer side is not easily transmitted to the light reflecting layer.
Even if the sheet itself is immersed in water or stored in a high-humidity atmosphere for a long period of time, the metal constituting the light reflection layer is hardly corroded or peeled off, resulting in excellent water resistance.

When polyethylene terephthalate is used as the material of the synthetic resin layer, the water resistance and moisture proof properties of the reversible thermosensitive recording sheet become particularly excellent, and moisture is contained in the thermosensitive recording material layer containing a vinyl chloride resin as a component. Even if it penetrates, it does not penetrate into the light reflection layer with, for example, hydrochloric acid, which is a decomposition product of the vinyl chloride resin, and the light reflection layer is hardly corroded.

When the reversible thermosensitive recording sheet of the present invention is manufactured, the light reflecting layer is covered with a synthetic resin layer and protected before forming the recording layer, so that the subsequent manufacturing steps, for example, an intermediate product can be performed. The surface of the light reflection layer can be prevented from being damaged in the step of winding into a roll.

The adhesive used for the reversible thermosensitive recording sheet of the present invention is a general laminating adhesive which does not contain a solvent having a solubility high enough to corrode metal, and may damage the light reflecting layer. There is no. Further, if a dry lamination method in which the adhesive is applied and the solvent is evaporated and then adhered is adopted, the solvent does not come into contact with the light reflection layer at all.

Further, in the reversible thermosensitive recording sheet of the present invention, visible light transmitted through the light-transmitting synthetic resin layer provided on one side of the recording layer is reflected on the light reflecting layer, and the visible light is reflected on the white turbid portion of the recording layer. An image is formed due to the contrast with the reflected visible light, but the image rises depending on the thickness of the synthetic resin layer so that the image has a three-dimensional appearance.

Such an action is preferable as a special effect of visibility. For example, as compared with a case where a character is directly written on a glossy metal surface, a character written on a mirror appears three-dimensionally. There is an advantage that the form of image display can be diversified so as to be seen.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION A reversible thermosensitive recording material used as a material for forming a recording layer in the present invention is prepared by, for example, blending a crystalline organic low-molecular compound in a dispersed state with a resin base material, and improving the transparency of the blend. Known reversible thermosensitive materials capable of displaying and erasing a visible image by reversibly changing with temperature can be used.

The resin constituting the base resin is preferably a resin having good transparency, film formability, elasticity and other heat resistance in a high temperature range, durability under repeated heating conditions, and the like. For example, the following are examples of suitable base resin types.

That is, examples of the base resin include polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride-vinyl acetate-alcohol copolymer, and other resins. Examples include vinyl acetate compounds, vinyl chloride copolymers, polyvinylidene chloride, vinylidene chloride copolymers, polyesters, polyamides, polystyrenes, polymethyl (meth) acrylates, and copolymers thereof.

Particularly, vinyl chloride-vinyl acetate copolymer, or vinyl chloride-vinyl acetate copolymer and ultraviolet (UV)
A mixture with a photo-curable resin such as a curable resin or a radiation-curable resin such as an electron beam (EB) curable resin has a high elastic modulus in a high-temperature region, and has a good durability when repeatedly rewritten (displayed / erased). It is.

The crystalline organic low-molecular compound to be mixed with the resin base material in a dispersed state includes carboxylic acid, dicarboxylic acid, ketone, ether, alcohol, ester and derivatives thereof. Alternatively, two or more kinds can be used as a mixture.

In particular, the use of an alkyl ester of a fatty acid having 12 or more carbon atoms as a crystalline organic low-molecular compound is preferable because this compound has a low melting point (mp).
It is also preferable to use an aliphatic dibasic acid having a high melting point (mp) having 10 or more carbon atoms in combination.

By appropriately adjusting the mixing ratio of the fatty acid alkyl ester and the aliphatic dibasic acid, it is possible to arbitrarily change the temperature range for transparency, the degree of transparency, and the degree of turbidity in the cloudy state. it can. It is preferable to set the mixing ratio in consideration of the performance of a printing / erasing apparatus that actually uses a reversible thermosensitive recording material, the sharpness of printing contrast, and the like.

The reversible thermosensitive recording material as described above is
Generally, it can be laminated in a layer on the surface of the object by solvent coating. Further, a lamination method by dispersion coating with a poor solvent, extrusion coating without a solvent, or a method of laminating a reversible thermosensitive recording material layer previously laminated on a release film by thermal transfer to an object can also be adopted. .

The synthetic resin layer provided on one side of the recording layer made of the reversible thermosensitive recording material is made of a light-transmitting synthetic resin, and is in the form of a film or a coating film. Examples of the resin include polyethylene terephthalate, polyethylene naphthalate, polyetherimide, polyetheretherketone, polysulfone, polyphenylenesulfide, polyarylate, polyethersulfone, polycarbonate, polyimide, acrylic resin, ultraviolet curable resin, electron beam curable resin, etc. It is preferable to employ a resin having excellent transparency and heat resistance.

The light reflecting layer using a metal as a reflecting material in the present invention may be any layer containing a metal having good optical reflectivity for improving the visibility of an image, and does not limit the kind of metal. . The light-reflective layer is used to make the image formed on the recording layer easier to see from the surface, and uses a light-reflective paint coating layer that is made of aluminum, tin, etc. deposited or bonded with foil or mixed with aluminum powder. You can also.

From the standpoint of color, gloss, cost, versatility, and the like, it is particularly preferable to form an aluminum deposition film. Aluminum deposited film is easily corroded by water, acid and alkali.Therefore, thin metal such as chromium and silicone metal is deposited on the surface of the deposited film.
It is preferable to improve the corrosion resistance without impairing the color and gloss of aluminum deposition.

As the metal deposition method, a well-known method such as a vacuum deposition method, sputtering, ion plating, and electron beam deposition method can be selectively adopted.

When forming a metal vapor-deposited film on the surface of a plastic film, not only direct vapor deposition but also a colored or uncolored adhesive layer may be previously provided on the surface of the film. A metal vapor-deposited film can also be formed via a layer.

The thickness of the light reflecting layer is several hundred angstroms (Å) in the case of a metal deposition film, but it is necessary to consider the color, gloss, manufacturing cost, strength, flatness, etc. of the image formed on the heat-sensitive recording sheet. The thickness may be determined as appropriate, and it is also possible to adopt a thickness that allows the base to be seen through.

The sheet substrate used in the present invention may be transparent or opaque. Examples of the resin material of the synthetic resin sheet substrate include polyethylene terephthalate,
Polyester resin such as polyethylene naphthalate, polypropylene, polystyrene, polycarbonate, polyvinyl chloride, polyethylene, polyamide, polyimide,
Examples thereof include polylactic acid, polysulfone, polyphenylene sulfide, polyetherimide, polyetheretherketone, and polyethersulfone. In particular,
Polyethylene terephthalate is a preferred resin in terms of heat resistance, strength, solvent resistance, mechanical strength, versatility, cost and the like.

An embodiment of the reversible thermosensitive recording sheet of the present invention and a method for producing the same will be described below with reference to the accompanying drawings.

As shown in FIG. 1, in the first embodiment, the light reflecting layer 2 is formed by depositing a light reflecting metal on the lower surface of the light transmitting synthetic resin film 1 in the drawing. in 1 of FIG upper surface a reversible thermosensitive recording sheet a ₁ forming the recording layer 3 by coating the reversible thermosensitive recording material.

Such a reversible thermosensitive recording sheet A ₁ is
If necessary, it can be used by bonding it to a sheet substrate made of a synthetic resin (not shown).

When the light reflecting layer is overlaid on another layer and integrated by adhesion, a dry laminating method (dry laminating method) is used.
It is preferable to employ With this laminating method, for example, a thermoplastic resin (vinyl acetate, vinyl chloride,
A solution obtained by dissolving an adhesive such as ethylene-vinyl acetate copolymer) in a solvent is uniformly applied to the surface to be bonded, dried, and then bonded and integrated under pressure to form a metal-deposited film. The solvent is less likely to come into contact with the light reflecting layer, and lamination and integration are possible.

The second embodiment shown in FIG. 2 relates to a process for manufacturing a reversible thermosensitive recording sheet. First, as shown in FIG. Is deposited to form a light reflecting layer 2, and then a sheet substrate 4 made of a synthetic resin is adhered to the light reflecting layer 2 by a dry lamination method. Then, as shown in FIG.
A recording layer 3 is formed by coating a reversible thermosensitive recording material on the upper surface of the synthetic resin film 1 to form a reversible thermosensitive recording sheet A.
Manufacture ₂ .

In the above-described manufacturing method, by adopting a thick synthetic resin film 1 on which metal deposition is performed, an effect such that recorded characters and the like appear three-dimensionally according to the thickness is remarkable. The use of a thin synthetic resin film has the advantage that the cost can be considerably reduced in proportion to the thickness of the film when metal deposition is performed.

In the third embodiment shown in FIG. 3, a light-reflecting metal is vapor-deposited on the upper surface of the sheet substrate 4 to form the light-reflecting layer 2. A light-transmitting synthetic resin film 1 is adhered, and then a reversible thermosensitive recording material is coated on the upper surface of the adhered synthetic resin film 1 to form a recording layer 3 and a reversible thermosensitive recording sheet (FIG. 2B)
Is manufactured.

Similarly, in a fourth embodiment described with reference to FIG. 3, a recording layer 3 is formed by coating a reversible thermosensitive recording material on the upper surface of a light-transmitting synthetic resin film 1 in advance.
The light reflecting layer 2 is formed by vapor-depositing a light-reflective metal on the upper surface of the separately provided sheet substrate 4, and the light reflecting layer 2 on the upper surface of the sheet substrate 4 and the lower surface of the synthetic resin film 1 are joined together. By bonding, all layers are integrated to produce a reversible thermosensitive recording sheet (the form shown in FIG. 2B).

In the manufacturing methods of the third and fourth embodiments,
If the thickness of the sheet substrate on which the metal deposition is performed is reduced, the cost for forming the light reflection layer formed of the metal deposition film can be reduced. When it is necessary to form a reversible thermosensitive recording sheet with a predetermined thickness according to the specifications of cards and sheets, if the thickness of the sheet base material is reduced, the thickness of the synthetic resin film is reduced accordingly. Thickness can be formed, and the effect of making an image look three-dimensional can be enhanced.

It is also possible to use a film other than the above as a material constituting the reversible thermosensitive recording sheet. In this case, the light-transmitting synthetic resin film is formed to be thin, and the image is formed three-dimensionally. It can also be adjusted so that it does not significantly enhance the effect that is shown.

Further, it is also possible to adjust the overall thickness of the reversible thermosensitive recording sheet by laminating several kinds of other films in addition to the illustrated film. Furthermore, a large number of general-purpose films in which a reversible thermosensitive recording material is applied and a recording layer is formed in advance are manufactured to meet the demand for sheets of various thicknesses.
It can also be handled by laminating a separately manufactured film.

[0050]

EXAMPLES AND COMPARATIVE EXAMPLES Example 1 One side of a transparent 188 μm thick polyethylene terephthalate resin film was subjected to aluminum vapor deposition, and the other side not subjected to aluminum vapor deposition was subjected to the following reversible heat-sensitive composition. Dissolve the recording material in tetrahydrofuran and apply,
The coating was cured by heating and drying in an oven for 5 minutes to remove the solvent to form a recording layer having a thickness of 10 μm. On the surface of this recording layer, a UV-curable resin diluted with isopropyl alcohol was applied, heated and dried, and then irradiated with UV light from a UV lamp to form a protective layer having a thickness of 2 μm, as shown in FIG. A reversible thermosensitive recording sheet having a cross-sectional shape was manufactured.

<Composition of Reversible Thermosensitive Recording Material> Vinyl chloride-vinyl acetate copolymer 100 parts by weight 12-trichosane (C ₁₁ H ₂₃ COC ₁₁ H ₂₃ , T _mB 68 ° C.) 44 parts by weight Eicosane diacid (HO ₂₎ CC ₁₈ H ₃₆ CO ₂ H, T _mC 126 ° C.) 4 parts by weight The obtained reversible thermosensitive recording sheet is punched out in a card form, heated in an oven at 80 ° C. for 1 minute, and then gradually cooled to room temperature. The recording layer was made transparent. Next, a part of the recording layer was given an energy of 0.30 mJ / dot at a pulse width of 1 msec with a thermal head of 8 dot / mm and a running speed of 40 mm / sec to display a clouded image (recording portion). The evaluation was made according to the items, and the results are shown in Table 1.

(A) Image contrast (recording density OD)
Value) The reflection density (OD value) of the transparent portion and the cloudy portion was measured with a reflection densitometer (Macbeth RD-914), and the contrast (transparent portion OD value-cloudy portion OD value) was examined.

(B) Corrosion Test of Light Reflective Layer The reversible thermosensitive recording sheet was immersed in water (tap water, room temperature) for one month or in a 5% aqueous solution of sodium carbonate (room temperature) for 24 hours. Was observed. The results were evaluated in two stages: corrosion (marked with ○) and no corrosion (marked with ×).

(C) Scratches on the surface of the light reflecting layer (the coated surface of the recording layer) Observed with the naked eye at the time of production, there were no scratches (indicated by 、) and scratches (×
) Was evaluated in two stages.

(D) Floating Character Effect of Printed Image The three-dimensional effect of the character by embossing was large (large), the three-dimensional effect was small (small), and there was no three-dimensional effect (none).

(E) Cost for Aluminum Evaporation Evaluation was made in two stages: low cost (○) and high cost (x) compared to the predetermined cost.

[0057]

[Table 1]

Example 2 An adhesive for dry lamination was applied to the surface of a transparent polyethylene terephthalate resin film having a thickness of 188 μm to a thickness of 1 μm according to the manufacturing method of the second embodiment described above (FIG. 2). After heating and drying to remove the solvent, the aluminum-deposited surface of a transparent polyethylene terephthalate resin film having a thickness of 12 μm and having one surface subjected to aluminum vapor-deposition treatment is superimposed on the adhesive-coated surface of the resin film, and is adhered by pressing. A composite film having a thickness of about 200 μm was produced.

A reversible thermosensitive recording material having the composition used in Example 1 was dissolved in tetrahydrofuran and coated on the surface of a resin film having a thickness of 12 μm of this composite film, and dried by heating in an oven at 110 ° C. for 5 minutes to remove the solvent. After removal, the coating was cured to form a recording layer having a thickness of 10 μm.

Thereafter, a protective layer having a thickness of 2 μm was formed of a UV-curable resin on the surface of the recording layer in exactly the same manner as in Example 1, and a reversible thermosensitive recording sheet having a cross-sectional shape shown in FIG. Was manufactured. Example 2 was also evaluated using the test items described above, and the results are also shown in Table 1.

Example 3 An adhesive for dry lamination was applied to a surface of a 188 μm thick transparent polyethylene terephthalate resin film to a thickness of 1 μm according to the manufacturing method of the third embodiment (FIG. 3) described above. After removing the solvent by heating and drying, the aluminum-deposited surface of a transparent polyethylene terephthalate resin film having a thickness of 12 μm having one surface subjected to aluminum vapor-deposition treatment is overlapped with the adhesive-coated surface of the resin film by pressure and adhered. About 200μm
Was prepared.

A reversible thermosensitive recording material having the composition used in Example 1 was dissolved in tetrahydrofuran and applied to the surface of a 188 μm thick resin film of the composite film.
The coating was cured by heating and drying in an oven for 5 minutes to remove the solvent to form a recording layer having a thickness of 10 μm.

Thereafter, a protective layer having a thickness of 2 μm made of an ultraviolet curable resin was formed on the surface of the recording layer in exactly the same manner as in Example 1, and a reversible thermosensitive recording sheet having a cross-sectional shape shown in FIG. Was manufactured. Example 3 was also evaluated by the above test items, and the results are also shown in Table 1.

Comparative Example A reversible thermosensitive recording material having the composition used in Example 1 was dissolved in tetrahydrofuran and applied to the aluminum-deposited surface side of a 188 μm-thick polyethylene terephthalate resin film having one surface subjected to aluminum vapor-deposition treatment. The coating was cured by heating and drying in an oven at 110 ° C. for 5 minutes to remove the solvent to form a recording layer having a thickness of 10 μm.

Thereafter, a protective layer having a thickness of 2 μm was formed on the surface of the recording layer by a UV-curable resin in the same manner as in Example 1 to produce a reversible thermosensitive recording sheet. The comparative examples were also evaluated using the test items described above, and the results are also shown in Table 1.

As is clear from the results shown in Table 1, by interposing a transparent plastic film between the metal deposition layer and the reversible thermosensitive recording material layer, aluminum deposition especially when immersed in water or alkaline water was performed. It has an effect of preventing corrosion of the film and does not stain or damage the metal deposition during coating of the heat-sensitive recording material. In addition, there is an effect that images such as characters on the recording layer can be seen and raised according to the thickness of the transparent synthetic resin film that protects the metal deposition layer, and the cost of metal deposition is reduced by using a thin synthetic resin film did it.

[0067]

According to the present invention, as described above, a light reflecting layer is provided on one side of a recording layer made of a reversible thermosensitive recording material via a protective layer such as a light transmitting synthetic resin layer. As a result, the light reflection layer becomes a protected reversible thermosensitive recording sheet, and the light reflection layer is less likely to be damaged or soiled in the production stage. In addition, it becomes a reversible thermosensitive recording sheet with excellent water resistance, and the reversible thermosensitive recording sheet does not cause corrosion or peeling of the metal deposition film of the light reflection layer even when immersed in water or stored for a long time in an atmosphere of high humidity. There is an advantage that it becomes a thermal recording sheet.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view of a reversible thermosensitive recording sheet according to a first embodiment.

FIG. 2 is an enlarged cross-sectional view of a reversible thermosensitive recording sheet illustrating a manufacturing process according to a second embodiment.

FIG. 3 is an enlarged cross-sectional view of a reversible thermosensitive recording sheet illustrating a manufacturing process according to third and fourth embodiments.

FIG. 4 is an enlarged sectional view of a conventional reversible thermosensitive recording sheet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Synthetic resin film 2, 12 Light reflection layer 3 Recording layer 4 Sheet base material 10 Thermal recording material layer 11 Plastic film

Claims (5)

[Claims] 1. A reversible thermosensitive recording sheet comprising a laminate having a recording layer made of a reversible thermosensitive recording material and a light reflection layer, and a protective layer provided between the two layers to protect the light reflection layer. 2. The reversible thermosensitive recording sheet according to claim 1, wherein the protective layer is a protective layer made of polyethylene terephthalate. 3. A recording layer made of a reversible thermosensitive recording material capable of displaying and erasing a visible image by reversibly changing transparency according to temperature, and having a light transmitting property on one side of the recording layer. A reversible thermosensitive recording sheet comprising a laminated body provided with a synthetic resin layer and a light reflecting layer made of a metal as a reflective material superposed on the synthetic resin layer. 4. The reversible thermosensitive recording sheet according to claim 3, wherein the light-transmitting synthetic resin is polyethylene terephthalate. 5. The reversible light according to claim 1, wherein the light reflection layer is an aluminum vapor deposition layer, or a light reflection layer in which a chromium vapor deposition layer or a silicone metal vapor deposition layer is provided on the aluminum vapor deposition layer. Thermosensitive recording sheet.