JPH08230333A - Thermally reversible recording medium and recording apparatus using the same - Google Patents

Abstract

PURPOSE: To provide a thermally reversible recording medium not generating warpage or the cracking or peeling of a protective layer and good in the close adhesiveness of a thermally reversible recording layer and the protective layer by making the resin being the main component of the recording layer same to the resin used in the protective layer. CONSTITUTION: A thermally reversible recording layer 25 using polyvinyl acetal and behenic acid is formed on a support 21 composed of polyethylene terephthalate and a protective layer 29 using polyvinyl acetal and organosiloxane (corosslinked one) is provided thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoreversible recording medium capable of reversibly repeating recording / erasing by a thermal means and a recording apparatus using the medium.

[0002]

2. Description of the Related Art Conventionally, a thermoreversible recording material has a characteristic that the transparency of the material (here, the transparency with respect to visible light will be discussed. The same applies hereinafter) is changed by thermal history.
Therefore, for example, by a thermal means such as a thermal head or the like, it is possible to make a display or the like by making the thermal history of a predetermined portion of the material different from other portions and making the transparency of both portions different. Becomes

As a conventional example of such a thermoreversible recording material, for example, there is one disclosed in JP-A-55-154198. The thermoreversible recording material disclosed in this publication was constituted by dispersing organic low-molecular compounds such as behenic acid (docosanoic acid) in a matrix material composed of a polymer such as polyester or a resin.

As a specific example of the above characteristics, Japanese Patent Laid-Open No. 55-
Japanese Patent No. 154198 describes examples having the following configurations 1 to 4. (1) A thermoreversible recording material containing a polymer linear copolyester based on an aromatic dicarboxylic acid and an aliphatic diol and docosanoic acid shows stable transparency when heated to 72 ° C. and cooled. It was It could only be returned to a cloudy state by reheating to a temperature above 77 ° C.

(2) A thermoreversible recording material containing a copolymer of vinylidene chloride and acrylonitrilo, docosanoic acid, and a fluorad lubricant for improving fluidity is 63 ° C.
When it was heated to and cooled, it showed stable transparency. It could only be returned to the opaque state by reheating to a temperature above 74 ° C. (3) The thermoreversible recording material containing a copolymer of vinyl chloride and vinyl acetate and docosanol showed stable transparency when heated to 68 ° C. and cooled. This is 70
It was possible to return to a cloudy state only by reheating to a temperature above ° C.

(4) The thermoreversible recording material containing polyester and docosanoic acid showed stable transparency when heated to 72 ° C. and cooled. It could only be returned to a cloudy state by reheating to a temperature above 77 ° C. However, in the above thermoreversible recording material, since a thermal head or the like is used during image formation, the recording layer is damaged or the recording layer composition adheres to the thermal head when the surface is heated by the thermal head or the like. However, when recording and erasing were repeatedly performed, the recording layer deteriorated and image formation became extremely difficult. Therefore, in order to improve these drawbacks, an ultraviolet curable resin or an electron beam curable resin (see JP-A-2-566) or a silicon-based graft polymer (see JP-A-2-86491) is used for the protective layer. A thermoreversible recording medium has been proposed.

[0007]

However, although details will be described later with reference to comparative examples, in the conventional thermoreversible recording medium, the resin as the main component of the thermoreversible recording layer and the resin used for the protective layer are used. However, when the protective film is formed on the recording layer, heating is performed to remove the solvent or to cure it.However, since the thermal contraction rate is different during cooling after heating, the recording medium may warp. In severe cases, the protective layer was cracked or peeled. Further, when the image information is erased, heating is performed, but for the same reason, the recording medium is warped, and in severe cases, the protective layer is cracked or peeled off.

Further, in the conventional thermoreversible recording medium, since the resin used as the main component of the thermoreversible recording layer and the resin used for the protective layer are different, the adhesion between the recording layer and the protective layer is not sufficient, and recording is not performed. There is also a problem that the recording layer and the protective layer are separated when the erasing is repeated. The present invention eliminates the above problems and makes the resin used as the main component of the thermoreversible recording layer the same as the resin used for the protective layer to protect the recording layer from warpage of the recording medium and cracks or peeling of the protective layer. An object of the present invention is to provide a thermoreversible recording medium having good adhesion to a layer and a recording device using the same.

[0009]

In order to achieve the above object, in the thermoreversible recording medium of the present invention, the resin as the main component of the thermoreversible recording layer and the resin used for the protective layer are made the same, and the protection is performed. The layer is characterized by using polyvinyl acetal and organosiloxane (but crosslinked). In addition, the case where the organosiloxane before curing remains in the protective layer is also included.

In the thermoreversible recording medium of the present invention, since the resin as the main component of the thermoreversible recording layer and the resin used for the protective layer are the same, warpage, cracking and peeling of the protective layer are suppressed. To be Further, the adhesion between the recording layer and the protective layer is sufficient, and the recording layer and the protective layer do not peel off even if recording and erasing are repeated. Further, depending on the purpose, additives such as a leveling agent, a filler, a polymerization inhibitor, a thermosetting catalyst, an anaerobic catalyst and the like may be used. Also, here, leaving time,
The heat treatment conditions are determined according to the type of organosiloxane so that the desired reaction can proceed.

Organosiloxanes used herein include, but are not limited to, methyl silicate, ethyl silicate, butyl silicate, propyl silicate, decyl silicate, dodecyl silicate, hexadecyl silicate, octadecyl silicate, trimethylmethoxysilane, Trimethylethoxysilane, trimethylbutoxysilane, phenyltrimethoxysilane, diphenyltrimethoxysilane, n-propyltrimethoxysilane, isobutyltrimethoxysilane, n-
Decyltrimethoxysilane, n-dodecyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-octadecyltrimethoxysilane, 1,6-bis (trimethoxysilyl) hexane, γ-ureidopropyltriethoxysilane, γ-dibutyl Aminopropyltrimethoxysilane, nonafluorobutylethyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ
-(2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropyldimethoxysilane, aminosilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, hexamethyldisilazane, dimethyldi Examples thereof include ethoxysilane, alkylalkoxysilanes, modified aluminum silicate, modified alkylsilicate and the like.

Further, commercially available organosiloxanes include, but are not limited to, for example, S
H6020, SH6020P, SH6023, SH60
26, SZ6030, SZ6032, SZ6040, S
Z6050, SH6062, SZ6050, SH606
2, SZ6072, SZ6075, SH6076, SZ
6079, SZ6083, SZ6187, SZ630
0, AY43-004, AY43-021, AY43-
043, AY43-077, AY43-040, AY4
3-047, AY43-075, AY43-048, A
Y43-045, AY43-065, AY43-08
3, AY43-031, AY43-034, AY43-
015, AY43-026, AY42-360 [product name, silane compound, Toray Dow Corning Silicone Co., Ltd.], ESTB-6000, ESTB-7000,
Grasmodoki X-500PA [trade name, TSB Development Center], MS51SG1, MS51SG2
[Product name, Mitsubishi Kasei Co., Ltd.] and the like.

The thermoreversible recording material used here includes, as a matrix material, polyvinyl butyral, polyvinyl acetal, polyvinyl acetal, and epoxy resin or phenol compound or epoxy compound or aldehyde compound or isocyanic acid compound, polyvinyl acetal and Epoxy resin (provided with curing agent), polyvinyl acetal and UV curable resin (provided with curing agent), polyvinyl acetal and organosiloxane (provided with crosslinking)
Is used. Examples of the saturated carboxylic acid that can be used include monocarboxylic acids having at least 10 carbon atoms, dicarboxylic acids having at least 10 carbon atoms, derivatives of monocarboxylic acids having at least 10 carbon atoms, and those having at least 10 carbon atoms. Certain dicarboxylic acid derivatives are preferred.

The reason why the above carboxylic acid has at least 10 carbon atoms is that it is not suitable for the present invention because the other carboxylic acid is in a liquid state at room temperature. Further, if the mixing ratio of the above-mentioned matrix material and the saturated carboxylic acid and its derivative is more than 1: 2 by weight of the saturated carboxylic acid and its derivative, it becomes difficult to form a film of the thermoreversible recording material. , 20: 1, the thermoreversibility becomes small, so it is preferable to set the ratio within the range of 1: 2 to 20: 1.

Regarding the mixing ratio of polyvinyl acetal used as a protective film and organosiloxane (cured), the composition of the charge (polyvinyl acetal and organosiloxane before curing) is 95 parts by weight of polyvinyl acetal. It has been confirmed that the effects of the present invention are exhibited from the case where both are mixed at a ratio of 5 parts by weight of the organosiloxane before curing. Further, the upper limit of mixing the organosiloxane is a range in which the occurrence of warpage and cracking and peeling of the protective layer can be suppressed, but at least 25 parts by weight of the polyvinyl acetal and 75 parts by weight of the organosiloxane before curing are used. It has been confirmed that cracking and peeling of the protective layer can be suppressed even when mixed with. From these facts, the mixing ratio of the polyvinyl acetal and the organosiloxane before curing is 95: 5 to 25: by weight.
It is considered that 75, more preferably about 90:10 to 50:50 is good.

Further, it is not limited to the case where only polyvinyl acetal and organosiloxane (which is cured) used as a protective film are contained,
In addition to these, it also means the case where other substances such as a substance that improves the film quality of the thermoreversible recording material and a substance that improves the lubricity are included. Further, in the present invention, the thermoreversible recording medium is specifically a prepaid card such as a telephone card, an orange card, a highway card, a postpaid card, a point card, or a label used in various fields. Further, it is a signboard of a signboard system, a recording paper for a word processor or a facsimile adopting a thermal recording system, and a sheet of a projection image forming apparatus such as an overhead projector or a slide.

[0017]

According to the thermoreversible recording medium of the present invention, as is clear from the experimental results described later, since the resin as the main component of the thermoreversible recording layer and the resin used for the protective layer are the same, It is possible to prevent warpage, cracking and peeling of the protective layer. In addition, the adhesion between the recording layer and the protective layer is sufficient, and the recording layer and the protective layer do not separate even when recording and erasing are repeated.

[0018]

Embodiments of the present invention will be described with reference to the drawings. It should be noted that the drawings used for the description are only schematically illustrated to the extent that the present invention can be understood. Further, it should be understood that the materials and numerical conditions used in this example are merely examples within the scope of the present invention, and therefore the present invention is not limited to these materials and numerical conditions. .

[A] The first invention (thermoreversible recording medium) will be described. (1) First, a first embodiment of the first invention (a thermoreversible recording medium) will be described. A thermoreversible recording layer composed of a thermoreversible recording material containing at least a matrix material and an organic low molecule and having a transparency that changes with heat history; a support for supporting the thermoreversible recording layer; In a thermoreversible recording medium having a protective layer on the opposite surface side directly or through an intermediate layer, first, as a first example, polyvinyl acetal as a protective layer, Sekisui Chemical Co., Ltd. ESTB-7000 [trade name, TSB Development Center] is prepared using KS-1 (trademark) as an organosiloxane. A recording layer prepared by using polyvinyl acetal and behenic acid is prepared as the recording layer.

Then, 50 parts by weight of S-REC KS-1 and 50 parts by weight of ESTB-7000 were dissolved in 500 parts by weight of tetrahydrofuran (hereinafter abbreviated as THF) to prepare a coating solution for the protective layer of the example. adjust. Liquid material obtained in this way (becomes a coating liquid for a thermoreversible recording medium)
Among them, the reaction between the polyvinyl acetal and the organosiloxane starts at the moment when the both are mixed, so that the liquid substance itself is finally solidified. In this first example, it has been found that it takes several weeks at room temperature for the liquid material to solidify.

By the way, if the liquid substance itself is solidified, it becomes impossible to coat the protective layer on the recording layer, so that the desired thermoreversible recording medium cannot be formed. In the case of the first embodiment, since it takes several weeks at room temperature until the liquid substance solidifies, it does not hinder the application, but among the other embodiments shown below. However, as some liquids solidify relatively quickly, it may be necessary to treat them. Considering such points, when preparing a liquid material, a treatment other than organosiloxane (here, polyvinyl acetal) is put in a solvent (here, THF), and the organosiloxane is added last. It is desirable to apply.

Next, in this first embodiment, as shown in FIG. 1, a polyethylene terephthalate substrate is prepared as the support 21. Then, a layer 25 of a thermoreversible recording material (hereinafter referred to as a thermoreversible recording layer) prepared by using polyvinyl acetal and behenic acid is prepared as a recording layer on the support 21. The above coating solution is applied to a predetermined thickness by the bar coating method. Next, this sample is heat-treated, for example, at a predetermined temperature for a predetermined time to obtain the protective layer 29. The heat treatment here is mainly performed under the condition that the THF used for preparing the coating solution can be removed. Here, in the atmosphere, 120
Heat treatment is performed at a temperature of ℃ for a predetermined time.

The thermoreversible recording layer 25 thus formed is opaque over its entire surface. Here, as a coating method, other suitable methods such as a roll coating method, a gravure coating method, and a blade coating method may be used. In the thermoreversible recording medium 20, solidification in the liquid state is necessary for several weeks at room temperature as described above. However, when it is in the state of a film, the polyvinyl acetal and the organosiloxane are different from those in the state of the liquid state. Since the reaction with the reaction proceeds easily, the target thermoreversible recording medium 20 can be obtained by an appropriate standing time shorter than that of the liquid material. However, when the standing time cannot be taken too long, heat treatment may be performed to accelerate the reaction.
In this example, the solvent in the coating (here, TH
The above reaction is also promoted in the heat treatment for removing F).

The support 21, the thermoreversible recording layer 25 formed on the support 21, and the thermoreversible recording layer 2
The structure composed of the protective layer 29 formed on the layer 5 can be said to be a thermoreversible recording medium having the most basic structure (the thermoreversible recording medium 20 of this embodiment). This thermoreversible recording medium 2
0, heat is applied to the thermoreversible recording layer 25 from the protective layer 29 side through the protective layer 29.
In addition to the method of heating (1), if the support 21 has good thermal conductivity, a method of heating the thermoreversible recording layer 25 from the support 21 side through the support 21 can be used.

In FIG. 1, the arrow labeled "light" indicates the state of incidence of light on the thermoreversible recording medium 20, and the arrow labeled "eye" indicates the thermoreversible recording. The direction in which an image formed on the medium 20 is viewed by a person is shown, and the arrow with the word "heating" indicates the direction in which heat is applied by the above two methods. (Less than,
The same applies to the thermoreversible recording medium after FIG. 4). This Figure 1
In this example, the image is recognized by the presence or absence of the reflected light from the thermoreversible recording medium 20. Of course, in the configuration of the thermoreversible recording medium 20 shown in FIG. 1, light may be made incident on the thermoreversible recording medium 20 from the support 21 side so that an image is recognized depending on the presence or absence of transmitted light. .

Next, the characteristics of the change in transparency with respect to the thermal history of the thermoreversible recording layer 25 will be examined. As a result, as shown in FIG. 2, the thermoreversible recording layer 25 was heated to a temperature of T ₂ or higher and then rapidly cooled (for example, 50 ° C./sec or higher) (in the case of the history shown by 11 in FIG. 2). ) It shows the maximum transparency, and when it is rapidly cooled (for example, 50 ° C./second or more) after being heated to T ₁ (T ₁ <T ₂ ) or more and T ₂ or less,
_When heated to an arbitrary temperature T _n of ₁ or more (however, the softening point of polyvinyl acetal (the temperature not exceeding 200 ° C. for S-REC KS-1)) and then gradually cooled (for example, less than 50 ° C./sec) ( (In the case of the history indicated by 13 in FIG. 1)
It has a thermal history-transparency characteristic of exhibiting the respective minimum transparency (white turbid state), and T ₁ = 80 ° C.,
It was found to be as shown at T ₂ = 120 ° C. That is, in the case of the thermoreversible recording medium 20 of the first example, the temperature at which the transparent state can be formed may be in the range of 120 ° C. to 200 ° C., and the range is 80 ° C., and the cloudy state can be formed. The temperature may be anywhere from 80 ° C to 200 ° C, with a range of 120 ° C.

Further, the transmittances of light having a wavelength of 550 nm (visible light) in the transparent state and the cloudy state of the thermoreversible recording layer of this example are respectively determined. The transmittance in the former state is 8
The transmittance was 0%, and the transmittance in the latter state was 4%. The contrast obtained from the ratio of these transmittances is 20. Regarding the thermoreversible recording layer 25 of this example, 140
Recording and erasing are repeated for 100 cycles, with one cycle consisting of a treatment of making transparent under the condition of heating at a temperature of ℃ and then rapidly cooling, and a treatment of making the liquid cloudy under a condition of heating again at a temperature of 140 ° C. and then gradually cooling. . Then, after 100 cycles, the transmittance is measured again to calculate the contrast. It was found that the contrast at this time was 20 as in the initial value.

The surface hardness of the thermoreversible recording medium of this example determined by the pencil hardness test method (JIS K5401) was as hard as 3H, and was resistant to mechanical damage. Further, in order to measure the warp of the thermoreversible recording medium of this example, the thermoreversible recording medium of this example was formed into a card shape (length 54 mm).
mm, width 86 mm, JIS standard “mold”), and record the image (character) with a thermal head, and then heat again to 140 ° C. and then gradually cool the solution to make it cloudy for one cycle. Recording / erasing process to be 1
Repeat 00 cycles. Then, after 100 cycles, as shown in FIG. 3, it was placed on the surface plate 15 and the gap between the long side direction (86 mm) and the short side direction (54 mm) was measured by the gap gauge. Both directions are 0.
It was a good value of 2 mm.

Next, the second to sixth embodiments will be described. The organosiloxane of the first embodiment is manufactured in the same manner except that the following is used. That is, (2) In Example 2, the organosiloxane of Example 1 was replaced with ESTB-6000 [trade name, TSB Development Center].

(3) In the third embodiment, the organosiloxane of the first embodiment is replaced with Grasmodoki X-500PA.
[Product name, TSB Development Center] (4) In Example 4, the organosiloxane of Example 1 was replaced with AY42-360, [Product name, silane compound, Toray Dow Corning Silicone Co., Ltd.].

(5) In the fifth example, the organosiloxane of the first example was replaced with SZ6070 [Product name, silane compound, Toray Dow Corning Silicone Co., Ltd.]. (6) In Example 6, the organosiloxane of Example 1 was replaced with MS51SG2, [Product name, Mitsubishi Kasei Co., Ltd.].

The drying conditions of the second to sixth embodiments were the same as those of the first embodiment. Furthermore, it was found that the initial contrast and the contrast after the 100 cycles of the clearing treatment and the clouding treatment were both 20. Further, it was found that the surface hardness obtained by the pencil hardness test method (JIS K5401) was 3H, 2H, 2H, 2H, 3H in the second to sixth examples, respectively. The gaps after repeating the recording / erasing process for 100 cycles are (0.2 mm, 0.2 mm) and (0.3 mm, 0.2) in the second to sixth examples, respectively.
mm), (0.3 mm, 0.3 mm), (0.2 mm,
0.2 mm) and (0.1 mm, 0.1 mm) (long side direction, short side direction).

Next, seventh to fifteenth embodiments will be described. The same procedure is carried out except that the recording layer prepared by using the polyvinyl acetal and behenic acid of the first embodiment is changed to the following one. (7) In the seventh embodiment, the recording layer of the first embodiment is replaced with polyvinyl butyral S-REC B (trade name, manufactured by Sekisui Chemical Co., Ltd.) and saturated carboxylic acid and its derivative behenic acid. .

(8) In the eighth embodiment, the recording layer of the first embodiment is made of polyvinyl acetal S-REC KS.
-1 [trade name, manufactured by Sekisui Chemical Co., Ltd.], epoxy resin Epomic R309 [trade name, manufactured by Mitsui Petrochemical Industry Co., Ltd.], and saturated carboxylic acid and its derivative behenic acid. (9) In the ninth example, the recording layer of the first example was prepared by using polyvinyl acetal S-REC KS-1 [trade name, manufactured by Sekisui Chemical Co., Ltd.] and phenol resin Praiophen 5030 [trade name, Dainippon Ink and Chemicals, Inc.] and saturated carboxylic acid and its derivative, behenic acid.

(10) In the tenth embodiment, the recording layer of the first embodiment is formed by using polyvinyl acetal S-REC KS-1 [trade name, manufactured by Sekisui Chemical Co., Ltd.] and epoxy compound Denacol EX-111. [Trade name, manufactured by Nagase Kasei Co., Ltd.] and saturated carboxylic acid and its derivative behenic acid were used. (11) In the eleventh embodiment, the recording layer of the first embodiment is made of polyvinyl acetal S-REC KS-1.
[Trade name, manufactured by Sekisui Chemical Co., Ltd.] and aminobenzaldehyde which is an aldehyde compound, saturated carboxylic acid and behenic acid which is a derivative thereof were replaced.

(12) In the twelfth embodiment, the recording layer of the first embodiment is replaced by polyvinyl acetal S-REC KS-1 [trade name, manufactured by Sekisui Chemical Co., Ltd.] and isocyanic acid compound octadecyl isocyanate. And behenic acid, which is a saturated carboxylic acid and its derivative. (13) In the thirteenth embodiment, the recording layer of the first embodiment is made of polyvinyl acetal S-REC KS-1.
[Brand name, Sekisui Chemical Co., Ltd.], epoxy resin Epomic R362 [Brand name, Mitsui Petrochemical Co., Ltd.], curing agent butylamine, saturated carboxylic acid and its derivative behenic acid I replaced it.

(14) In the fourteenth embodiment, the recording layer of the first embodiment is prepared by using the polyvinyl acetal S-REC KS-1 (trade name, manufactured by Sekisui Chemical Co., Ltd.) and the UV curable resin UPIMER SA-. 1002 [trade name, manufactured by Mitsubishi Petrochemical Co., Ltd.] was replaced with benzophenone as a photoreaction initiator, saturated carboxylic acid and behenic acid as a derivative thereof.

(15) In the fifteenth embodiment, the recording layer of the first embodiment is prepared by using the polyvinyl acetal S-REC KS-1 [trade name, manufactured by Sekisui Chemical Co., Ltd.] and the organosiloxane ESTB-7000 [. Product name, (Yes)
TSB Development Center] and saturated carboxylic acid and its derivative, behenic acid. The drying conditions for the protective layers in the seventh to fifteenth examples were the same as in the first example.

Further, it was found that the initial contrast and the contrast after 100 cycles of the clearing treatment and the clouding treatment were both 20. Further, the surface hardness obtained by the pencil hardness test method (JIS K5401) is 2H, 2H, and 7H in the seventh to fifteenth examples, respectively.
It was found to be 2H, 3H, 2H, 2H, 4H, 4H, 4H. The gaps after the recording / erasing process was repeated 100 cycles were (0.2 mm, 0.2 mm) and (0.3 mm, respectively) in the seventh to fifteenth examples.
0.2 mm), (0.3 mm, 0.3 mm), (0.2
mm, 0.2 mm), (0.1 mm, 0.1 mm),
(0.2mm, 0.2mm), (0.4mm, 0.3m
m), (0.4 mm, 0.4 mm), (0.4 mm,
It was found to be 0.3 mm). (Long-side direction, short-side direction) Next, a sixteenth embodiment of the first invention (thermoreversible recording medium)
The eighteenth embodiment will be described.

The same preparation is carried out except that the compounding ratio of polyvinyl acetal and organosiloxane of the first embodiment is changed to the following. (16) In the sixteenth example, the compounding ratio of the polyvinyl acetal and the organosiloxane of the first example was changed to S-REC KS-1,95 parts by weight and ESTB-7000,5 parts by weight.

(17) In the seventeenth embodiment, the mixing ratio of the polyvinyl acetal and the organosiloxane of the first embodiment is S-REC KS-1,75 parts by weight and ESTB-7.
It was replaced with 000,25 parts by weight. (18) In the eighteenth embodiment, the mixing ratio of the polyvinyl acetal and the organosiloxane of the first embodiment is S-REC KS-1,25 parts by weight and ESTB-7000,75.
Parts by weight were replaced.

The drying conditions of the protective layer in the 16th to 18th embodiments were the same as those in the first embodiment. Furthermore, it was found that the initial contrast and the contrast after the 100 cycles of the clearing treatment and the clouding treatment were both 20. Furthermore, the pencil hardness test method (JIS K
It was found that the surface hardness obtained by 5401) was 2H, 3H, and 4H in the second to sixth examples, respectively. The gaps after the recording / erasing process was repeated 100 cycles were (0 mm, 0 mm) and (0.1 mm, 0.1 m) in the 16th to 18th embodiments, respectively.
m), (0.5 mm, 0.4 mm) (long side direction, short side direction).

Comparative Example [1] Comparative Example 1 Further, a thermoreversible recording medium in which the protective layer of the present invention was not formed in the first example, that is, only a recording layer prepared using polyvinyl acetal and behenic acid was prepared. To do.
Then, the characteristics of this layer are measured in the same manner as in the first embodiment.

The thermoreversible recording layer of Comparative Example 1 was made transparent by heating to 140 ° C. and then rapidly cooling, and then heated again to 140 ° C. and then gradually cooled. The recording / erasing process is repeated 100 times, which is one cycle of the process of making the liquid cloudy. And 100
After the end of the cycle, the transmittance is measured again to calculate the contrast. At this time, the transmittance in the transparent state was 80%, and the transmittance in the cloudy state was 20%. Therefore, it was found that the contrast was 4, which was 20 while the initial value was worse.

Further, in order to measure the warp of the thermoreversible recording medium of Comparative Example 1, the thermoreversible recording medium of Comparative Example 1 was punched out into a card shape (length 54 mm, width 86 mm, JIS standard “mold”). The recording / erasing process is repeated for 100 cycles, in which the process of recording an image (characters) with the thermal head and the process of clouding under the condition of being heated again to a temperature of 140 ° C. and then gradually cooled are one cycle. And
After 100 cycles, it was placed on the surface plate 15 as shown in FIG. 3 and the gap in the long side direction (86 mm) and the short side direction (54 mm) was measured with a gap gauge. It was a good value.

Further, the thermoreversible recording layer of Comparative Example 1 was made transparent under the condition of heating to 70 ° C. and cooling, and the surface hardness determined by the pencil hardness test method (JIS K5401) was F. It was found to be a thermoreversible recording medium that is worse than any of the present invention and is weak against mechanical scratches. [2] Comparative Example 2 Further, the compounding ratio of the polyvinyl acetal and the organosiloxane of the first example was S-REC KS-1,0 parts by weight,
1st except that ESTB-7000, 100 parts by weight
The protective layer coating solution of Comparative Example 2 is prepared in exactly the same manner as in the example, and a recording layer prepared using polyvinyl acetal and behenic acid is prepared as the recording layer. Then, a protective layer is formed as in the first embodiment. Each of these characteristics is measured.

The thermoreversible recording layer of Comparative Example 2 was heated to a temperature of 140 ° C. and then rapidly cooled, and then transparentized, and then heated again to a temperature of 140 ° C. and then gradually cooled. The recording / erasing process is repeated 100 times with one cycle of the process of making the liquid cloudy under certain conditions. And 1
After the completion of the 00 cycle, the transmittance is measured again to calculate the contrast. At this time, the transparent state has a transmittance of 80.
%, And the transmittance in the cloudy state was 4%. Therefore, the contrast was a good value of 20.

Further, in order to measure the warp of the thermoreversible recording medium of Comparative Example 2, the thermoreversible recording medium of Comparative Example 1 was punched out into a card shape (length 54 mm, width 86 mm, JIS standard “mold”). The recording / erasing process is repeated for 100 cycles, in which the process of recording an image (characters) with the thermal head and the process of clouding under the condition of being heated again to a temperature of 140 ° C. and then gradually cooled are one cycle. And
After 100 cycles, the plate was placed on the surface plate 15 as shown in FIG. 3 and the gap in the long side direction (86 mm) and the short side direction (54 mm) was measured with a gap gauge. It was found to warp violently (0.0 mm, 3.0 mm). In such a warped thermoreversible recording medium, when used as a prepaid card in actual use,
Due to the warp, it becomes impossible to insert the recording device. There is no exact regulation, but the warp in the long side and short side directions is 1.0mm and 0.7mm in the long side direction and the short side direction, respectively.
The following is desirable.

The thermoreversible recording layer of Comparative Example 1 was made transparent under the conditions of heating at 70 ° C. and cooling, and the pencil hardness test method (JIS K5401) was also used.
It was found that the surface hardness obtained by the method was as good as 2H. The main structure of the thermoreversible recording medium of the first invention (the thermoreversible recording medium) will be described below.

(1) The most basic structural example (first embodiment) of the thermoreversible recording medium of the first invention is as described above with reference to FIG. That is, it is composed of the thermoreversible recording material of the first invention, and has a structure in which the thermoreversible recording layer of the first invention, a support for maintaining this layer, and a protective layer are laminated. Here, the support may have any suitable shape, constituent material, and film thickness depending on the design of the thermoreversible recording medium. For example, a material that is transparent to visible light, one that reflects part or all of visible light, or one that absorbs part or all of visible light can be the support of the invention described below.

In the case of the structure of the first invention, the transparent portion and the cloudy portion are selectively formed in the thermoreversible recording layer by selectively heating the thermoreversible recording layer from the thermoreversible recording layer side. be able to. That is, the display can be performed.
Further, when the support is made of a material having a good thermal conductivity, a heating means is brought into contact with the support to heat the thermoreversible recording layer through the support. The transparent portion and the cloudy portion can be selectively formed (display can be performed) (from the back side of the thermoreversible recording medium).

In the case where the display can be made also from the support side, when the thermoreversible recording medium is used as the display screen itself of the display device, the heating means is arranged on the side where the person looks at the thermoreversible recording medium. The advantage is that the desired display can be performed without doing so. When it is possible to display from the support side (from the back side of the thermoreversible recording medium), depending on the design,
In addition to the above advantages, other advantages are obtained (details will be described later in the corresponding embodiments).

Examples of the constituent material of the support include, but are not limited to, polyethylene terephthalate,
Polyester, polypropylene, cellophane, polyvinyl chloride, polyolefin, polyvinyl alcohol, polyvinylidene chloride, polystyrene, polyamide, polycarbonate, polyarylate, polysulfone, fluororesin, polyacrylonitrile, polyether sulfone,
Examples thereof include plastics such as polybutadiene and polyimide, papers, synthetic papers, inorganic fiber papers having good thermal conductivity, ceramics, metals, and plastics having carbon powder or metal powder dispersed therein.

Further, in order to expand the applications of the thermoreversible recording medium of the first invention and further improve the characteristics, in addition to the constitution of the first embodiment, an intermediate layer for protecting the thermoreversible recording medium is provided. From the protective layer, the adhesive layer for improving the fixing strength between the components of the thermoreversible recording medium, the reflective layer or the light absorbing layer (details will be described later), and the enhance layer for improving the display contrast, the thermoreversible One or more layers selected according to the design of the magnetic recording medium, and further, a recording layer for recording bar code information, magnetic information and the like which can be read by an information reading device or the like but cannot be directly recognized by humans (the present invention. A recording layer having a meaning different from that of the thermoreversible recording layer) can be arbitrarily and appropriately arranged to form a thermoreversible recording medium.
These specific examples will be described by the following examples.

(19-22) The nineteenth to twenty-second embodiments of the first invention will be described. As shown in FIG. 4, the thermoreversible recording medium of Example 19 includes a support 21 and a support 21.
Of the reflective layer or the light absorbing layer 23 as a kind of intermediate layer provided on the upper surface of the, and the thermoreversible recording layer 25 and the protective layer shown in the first embodiment provided on the upper surface of the reflective layer or the light absorbing layer 23. 29 and 29. Further, in each of the cross-sectional views used in FIG. 4 and the following description, hatching showing the cross-section is attached only to the reflective layer or the light-absorbing layer 23 and the thermoreversible recording layer 25, and hatching to other layers is omitted. are doing.

The thermoreversible recording medium 40 of the nineteenth embodiment was prepared as follows. The support 21 is
Here, it is made of a polyethylene terephthalate substrate having a predetermined thickness. On this support 21, a coating solution prepared by dissolving vinyl chloride-vinyl acetate copolymer [VYHH manufactured by Union Carbide Co. (UCC)] as a binder and cadmium red as a color pigment in tetrahydrofuran is applied. When the obtained coating film is dried, a layer that mainly reflects red light on the support 21 and absorbs or transmits other light, that is, depending on the wavelength of interest, is a reflection layer or a light absorption layer. It can be said that it is a light transmitting layer, or from another perspective, a layer 23 that is also a colored layer (this layer is referred to as a reflecting layer or a light absorbing layer).

The thermoreversible recording layer 25 was formed on the reflection layer or the light absorption layer 23 thus produced by using the coating solutions used in the first to sixth examples of the first invention. The first
It is formed by the procedure described in the embodiment of the invention. A heating means (for example, a thermal head) is brought into contact with the thermoreversible recording layer 25 of the thermoreversible recording medium 40, and the thermoreversible recording layer 25 is selectively heated to form a transparent portion (printing portion). However, I was able to print in red letters. In addition, repeated recording and erasing experiments were conducted in the same manner as above, and it was found that no deterioration of printing was observed. Of course, also in the case of the nineteenth embodiment, like the first embodiment, the support 21 is made of a material having good heat conduction, and the support 2 is inserted from the support 21 side.
The thermoreversible recording layer 25 may be heated via 1.

The reflection layer or the light absorption layer 23 is not limited to the layer including a red pigment. The pigment used is not red, or a layer containing a dye,
Alternatively, the reflection layer or the light absorption layer 23 may be formed of a layer containing metal powder such as copper powder or aluminum powder. Further, the reflection layer or the light absorption layer 23 may be formed by applying ink or the like on the support 21. Also, inks of a plurality of colors may be printed for the purpose of improving the display contrast. In addition, when the reflective layer or the light absorption layer 23 is manufactured, a pigment, a coloring matter, and a metal powder having good thermal conductivity are used so as to improve the thermal responsiveness of the thermoreversible recording medium 40. You can also

As the constituent material of the protective layer 29, for example,
The same polyvinyl acetal and organosiloxane as in the first embodiment of the first invention are used. As another example,
Examples of the second to eighteenth examples of the first invention and other organosiloxanes include organosiloxanes [organosiloxane used here is MS51S described above.
G2 [trade name, Mitsubishi Kasei Co., Ltd., etc.] can be mentioned.

The thickness of the protective layer 29 is the same as that of the thermoreversible recording layer 25.
The film thickness may be a suitable range within which heat from a means for heating (eg, a thermal head) is satisfactorily transferred to the thermoreversible recording layer 25 and a function as a protective layer is obtained. Incidentally, of the surface of the protective layer 29, the thermoreversible recording layer 2
Characters and figures (for example, the use of the thermoreversible recording medium 40, for example, "○"
Characters such as "XX card" may be printed. Also in the case of the nineteenth embodiment, the support 21 can be made of a material having good heat conduction. With this configuration,
In addition to the fact that printing can be performed without providing a heating means on the side of the medium viewed by the person, the effect that the heat from the heating means is less likely to affect the characters and figures printed on the surface of the protective layer 29 is obtained. This is considered to be effective in protecting the written characters and figures when writing characters and figures with water-based or oil-based magic ink on the surface of the protective layer 29.

If necessary, as shown in FIG. 5 (twentieth embodiment), between the protective layer 29 and the thermoreversible recording layer 25 and / or the thermoreversible recording layer 25 and the reflective layer or Between the light absorption layer 23, both layers 25, 2 as one layer of the intermediate layer
You may provide the adhesive layer 31 for improving the adhesive strength of 3. Examples of the constituent material of the adhesive layer 31 include, but are not limited to, polyester resin, urethane resin, and epoxy resin.

Further, as another example of the intermediate layer, as shown in FIG.
As shown in the first embodiment, a dedicated layer (printing layer) 33 for printing characters and graphics can be provided between the adhesive layer 31 and the protective layer 29. Further, FIG. 7 (22nd Example) shows an example of a thermoreversible recording medium 40 having a printing layer 33 between a reflection layer or a light absorption layer 23 and an adhesive layer 31. Of course, the provision of the adhesive layer and the printing layer is not limited to these embodiments, and can be applied to other embodiments.

(23-24) The 23rd-24th embodiments of the first invention will be described. As shown in FIG. 8, the thermoreversible recording medium 50 of the twenty-third embodiment has an intermediate structure between the thermoreversible recording layer 25 and the reflecting layer or the light absorbing layer 23 in addition to the structure of the thermoreversible recording medium. As one kind of layer, an enhancement layer 35 for improving display contrast is provided. The enhancement layer 35 enhances the contrast between the transparent portion and the cloudy portion formed on the thermoreversible recording layer 25 to improve the display contrast. Examples of the constituent material of the enhancement layer 35 include, but are not limited to, polyester, polyethylene, polypropylene, cellophane, polyvinyl chloride, polyolefin, polyvinyl alcohol, polyvinylidene chloride, polystyrene, polyamide, polycarbonate, polyarylate, polysulfone, and the like. Fluorine resin, polyacrylonitrile, polyether sulfone, polybutadiene, polyimide, UV
Plastic such as cured resin, or SiO ₂ , TiO ₂ ,
Inorganic substances such as Al ₂ O ₃ can be mentioned.

Further, as shown in FIG. 9 (the twenty-fourth embodiment), the enhancement layer may be composed of the air layer 35a. Here, an adhesive layer 31 is provided in a part between the reflective layer or the light absorbing layer 23 and the thermoreversible recording layer 25, and between the reflective layer or the light absorbing layer 23 and the thermoreversible recording layer 25,
An air layer 35a is formed in a portion where the adhesive layer 31 is not provided to form an enhance layer.

Also in the case of these examples, the support 2
1 can be made of a material having a good thermal conductivity. However, it is considered that it is not so effective in the mode in which the enhancement layer is composed of the air layer 35a because the air layer 35a reduces the degree of heat transfer to the thermoreversible recording layer 25. (25-26) The 25th-26th embodiments of the first invention will be described.

The thermoreversible recording medium 60 of the twenty-fifth embodiment is
As shown in FIG. 10, the thermoreversible recording layer 25 provided in the thermoreversible recording medium 60 records visible characters and figures. However, if the thermoreversible recording medium of the first invention can also store coded information and is rewritable, a directly visible thermal record will record information combined with the coded record. And a thermoreversible recording medium that can be used is obtained, which is preferable.

If such a thermoreversible recording medium can be constructed, it can be used to construct a prepaid card, for example, and code information indicating a balance or the like can be recorded in this recording layer. Furthermore, this balance information is read by an external reading device, a new balance is calculated from this information and the amount of money that has just been used by the external control device, and this new balance is displayed on the thermoreversible recording layer and It is preferable because the application of the thermoreversible recording medium is widened such that renewal recording becomes possible. Hereinafter, an example (25th Example) of a thermoreversible recording medium having such a recording layer will be described.

Where the recording layer capable of recording / rewriting the code information is provided in the thermoreversible recording medium can be arbitrarily set according to the design of the thermoreversible recording medium. In this embodiment, as shown in FIG. 10, a recording layer 37 is provided on the back surface of the support 21 of the thermoreversible recording medium described with reference to FIG.
Further, in order to protect the recording layer 37, the recording layer 3
A second protective layer 39 that covers 7 is provided. Further, as shown in FIG. 11 (the twenty-sixth embodiment), an enhancement layer 35 may be provided between the thermoreversible recording layer 25 and the reflection layer or the light absorption layer 23. The constituent material of the second protective layer 39 can be selected from various materials that can form the protective layer 29, for example.

The recording format on the recording layer 37 is not limited to this, but is magnetic recording, optical recording, electrical recording, or heat for recording invisible code information. It may be one or more of the recording methods. The recording layer 37 may be composed of, for example, the IC card itself. Also in these examples, the support 21 may be made of a material having good heat conduction.

(27 to 28) The 27th to 28th embodiments of the first invention will be described. As shown in FIG. 12, the thermoreversible recording medium 70 of the twenty-seventh embodiment comprises a transparent support 41 composed of a material transparent to visible light, and a thermoreversible recording layer 25 in this order, and a transparent support. The back surface of 41 is provided with a reflection layer or a light absorption layer 23. In this structure, a transparent support 41 is used as a support, and the transparent support 41 is used as the support.
Since it is arranged between the reflection layer and the light absorption layer 23,
The transparent support 41 itself acts as an enhancement layer. Of course, as shown in FIG. 13 (28th embodiment), in addition to the configuration of FIG. 12 (27th embodiment), the original enhancement layer 35 (between the transparent support 41 and the reflection layer or the light absorption layer 23 ( The air layer 35a may be provided).

As an example of the constituent material of the transparent support 41,
Transparent plastics such as polyester, polyethylene, polypropylene, cellophane, polyvinyl chloride, polyolefin, polyvinyl alcohol, polyvinylidene chloride, polystyrene, polyamide, polycarbonate,
Examples thereof include polyarylate, polysulfone, fluororesin, polyacrylonitrile, polyether sulfone, and polybutadiene.

Also in the case of these embodiments, for example, in the structure of FIG. 12 or FIG. 13, the recording layer 37 and the second layer are provided under the reflection layer or the light absorption layer 23 as shown in FIG. 10 or 11.
The protective layer 39 of FIG. (29-31) The 29th-31st embodiments of the first invention will be described. The thermoreversible recording medium 40 shown in FIG. 4, the thermoreversible recording medium 40 shown in FIG. 5, the thermoreversible recording medium 40 shown in FIG. 7, and the thermoreversible recording medium 50 described with reference to FIG. , In each structure, the reflection layer or the light absorption layer 2
3 is not provided, and the support 21 itself is composed of a transparent support. 14 and 15 are shown as the 29th and 30th embodiments.

Here, FIG. 14 shows an example in which heating is performed from the protective layer 29 side of the thermoreversible recording medium 80 to print on the thermoreversible recording layer 25, and FIG. 15 shows the transparent support 41 in terms of thermal conductivity. This is an example in which a good material and a transparent material are used, and heating is performed from the support 41 side to print on the thermoreversible recording layer 25. In both cases, an example is shown in which light is incident from the transparent support 41 of the thermoreversible recording medium 80. Of course, the light may be introduced from the protective layer 29 side.

As another mode of the twenty-ninth and thirtieth embodiments, an example in which the idea of the twenty-ninth and thirtieth embodiments is applied to the constitution including the recording layer 37 is shown in FIG. 16 (thirty-first embodiment). . That is, in FIG. 16, an example in which the recording layer 37 and the second protective layer 39 for protecting the recording layer 37 are provided on a portion of the back surface of the transparent support 41 that does not hinder the incidence of light. Shows. Of course, in the case of FIG. 16 as well, the transparent support 41 may be made of a material having a high thermal conductivity, and the thermoreversible recording layer 25 may be heated via the transparent support 41.

(32-34) The 32nd-34th embodiments of the first invention will be described. 1st and 19th to 3rd described above
1, the thermoreversible recording medium 20, 30, 40, 5
0, 60, 70, and 80 were for viewing the data printed on the medium mainly from the protective layer 29 side. However, the support 21 itself is composed of the transparent support 41, and the position where the reflective layer or the light absorption layer 23 is provided is located at the thermoreversible recording layer 25 and the protective layer 29.
Alternatively, the print data may be viewed from the transparent support 41 side. Some examples will be described below. However, in the case of this 32nd Example (see FIG. 17), the protective layer 29 of the thermoreversible recording medium 90 may not have transparency.

First, FIG. 17 (thirty-second embodiment) is a thermoreversible recording in which a thermoreversible recording layer 25, a reflective layer or a light absorbing layer 23, and a protective layer 29 are provided in this order on the lower surface of a transparent support 41. It is an example of the medium 90. This corresponds to an example in which the thermoreversible recording medium 40 of FIG. 4 is changed so that the display can be seen on the side of the support 21. In addition, in FIG. 18 (third embodiment), an adhesive layer 31, a thermoreversible recording layer 25, an adhesive layer 31, a reflective layer or a light absorbing layer 23, and a protective layer 29 are provided in this order on the lower surface of a transparent support 41. Here is an example. This corresponds to an example in which the thermoreversible recording medium 40 of FIG. 5 is changed so that the display can be seen on the side of the support 21. In addition, in FIG. 19 (34th embodiment), a printing layer 33, an adhesive layer 31, a thermoreversible recording layer 25, an adhesive layer 31, a reflection layer or a light absorbing layer 23, and a protective layer 29 are provided on the lower surface of the transparent support 41. This is an example provided in this order. This corresponds to an example in which the thermoreversible recording medium 40 of FIG. 6 is changed so that the display can be seen on the side of the support 21.

(35 to 37) The 35th to 37th embodiments of the first invention will be described. FIG. 20 (35th embodiment) shows that the adhesive layer 31, the thermoreversible recording layer 2 is provided on the lower surface of the transparent support 41.
5, adhesive layer 31, printing layer 33, reflection layer or light absorption layer 23
And the thermoreversible recording medium 10 in which the protective layer 29 is provided in this order.
1 is an example. This corresponds to an example in which the thermoreversible recording medium 40 of FIG. 6 is changed so that the display can be seen on the side of the support 21. 21 (thirty-sixth embodiment) is an example in which a thermoreversible recording layer 25, an enhancement layer 35, a reflection layer or a light absorption layer 23, and a protective layer 29 are provided in this order on the lower surface of a transparent support 41. This corresponds to an example in which the thermoreversible recording medium 50 of FIG. 8 is changed so that the display can be seen on the support 21 side. FIG.
The thirty-seventh embodiment is an example in which a thermoreversible recording layer 25, an enhancement layer composed of an air layer 35a, a reflection layer or a light absorption layer 23, and a protective layer 29 are provided in this order on the lower surface of the transparent support 41. . This corresponds to an example in which the thermoreversible recording medium 50 of FIG. 9 is changed so that the display can be seen on the support 21 side.

(38-39) The 38th-39th embodiments of the first invention will be described. In FIG. 23 (38th embodiment), a thermoreversible recording layer 25, a reflection layer or a light absorbing layer 23, a recording layer 37 and a second protective layer 39 are provided in this order on the lower surface of a transparent support 41. 2 is an example of the sex recording medium 110. This corresponds to an example in which the thermoreversible recording medium 60 of FIG. 10 is changed so that the display can be seen on the support 21 side. In FIG. 24 (thirty-ninth embodiment), the thermoreversible recording layer 25, the enhancement layer 35 (which may be an air layer), the reflection layer or the light absorption layer 23, the recording layer 37, and the thirty-sixth layer are provided on the lower surface of the transparent support 41. This is an example in which the second protective layer 39 is provided in this order. This corresponds to an example in which the thermoreversible recording medium 60 of FIG. 11 is changed so that the display can be seen on the support 21 side.

(40) The 40th embodiment of the first invention will be described. In each of the above-described embodiments, as a support used when light is incident from the support 21 side, a structure in which light enters the main surface of the support 21 at a right angle is mainly considered. However, the support 21 itself may have the property of changing the direction of the light incident on the support 21. This is because, for example, restrictions on the design of the thermoreversible recording medium due to the positional relationship between the thermoreversible recording layer 25 and the light source can be reduced.

FIG. 25 is a diagram showing an aspect of the 40th embodiment. In this mode, when light is incident from the end face 51a of the plate-shaped body 51, the light is bent at a right angle in the plate-shaped body 51 and is emitted from the main surface of the plate-shaped body 51 (also called an edge light system. ) An example is shown in which the plate-shaped body 51 having an optical path changing function is used as a support for the thermoreversible recording medium 120. Specific examples of such a plate-like body 51 include acrylite (trade name) submitted by Mitsubishi Rayon Co., Ltd. using an acrylic resin. Of course, the structure to which the idea of the forty-first embodiment can be applied is not limited to that of FIG. 25, but can be widely applied to the structures of the above-described embodiments.

[B] Next, the writing of information on the thermoreversible recording medium will be described. Next, an example of a method for writing information on the thermoreversible recording medium described above will be described. FIG. 26 is an explanatory diagram of the writing of information to the thermoreversible recording medium, and an example of an apparatus for writing information to the thermoreversible recording medium 100 and the thermoreversible recording medium 100.
Shows the relationship with.

In FIG. 26, reference numerals 200a to 200c denote recording devices having somewhat different functions.
0 is information for recording (for example, "A""I""U""E")
"O") and stores the recording devices 200a to 200c
Is a control device for controlling. Here, the recording device 2
Reference numeral 00a includes an information printing thermal head 201 and an information erasing heating block (or heating roll) 202. The recording device 200b includes, in addition to the configuration of the recording device 200a, an optical reading device 203 for reading information of the recording layer 37 described above, in particular, information recorded by an optical recording method. The recording device 200c includes, in addition to the configuration of the recording device 200a, a read head 204 for reading information on the recording layer 37, particularly coded information, and a recording head 205 for writing the coded information.

(1) When the thermoreversible recording medium 100 has, for example, a structure not having the recording layer 37 described above, the user inserts the thermoreversible recording medium 100 into the recording apparatus 200a. The control device 300 senses that the thermoreversible recording medium 100 is inserted, and prints the information for recording (for example, "A""I""U""E""O"). Send a command to.

Receiving this command, the recording apparatus 200a uses the thermal head 201 and with a predetermined power for a predetermined time.
The thermoreversible recording layer 25 of the thermoreversible recording medium 100 is selectively heated directly or through the protective layer 29 or the support 21. If the thermoreversible recording medium 100 has the thermal history characteristic shown in FIG.
120 to the part where you want to print "I", "U", "E", "O"
After heating to 200 ° C., and rapidly cooling to room temperature, the relevant part becomes transparent and the other parts remain cloudy. In addition, the above-mentioned printing uses printing power of, for example, 0.1 W /
Dots and the printing time is 1 msec. Of course, this printing condition is an example.

After the printing is completed, the user takes out the thermoreversible recording medium 100 from the recording device 200a. The thermoreversible recording medium 100 taken out is “A” “I” “U” “E”
The printed part of "O" was fixed in a transparent state. Further, the contrast represented by the transmittance ratio between the transparent portion and the cloudy portion was, for example, 20 (which is referred to as the transmittance for light having a wavelength of 550 nm). As a result, the user can visually recognize the information “A” “I” “U” “E” “O” recorded on the thermoreversible recording medium 100.
Further, this information "a""i""u""e""o" is held until the next use of the medium.

In addition, the user is advised to use the thermoreversible recording medium 100.
When erasing the previously recorded information, the thermoreversible recording medium 100 is inserted into the recording device 200a. Recording device 20
In the case of the thermoreversible recording medium 100 having the heat history characteristic of FIG. 1, 0a heats the thermoreversible recording medium by the heating roll 202 in the temperature range of 90 to 200 ° C. and then gradually cools it to room temperature. The thermoreversible recording medium 100 becomes opaque and the previous record is erased. In addition, when new information is recorded on the erased medium, it is processed by the above printing procedure.

(2) In the case where the thermoreversible recording medium 100 has, for example, the above-mentioned recording layer 37, in particular, a recording layer for recording information by an optical recording method, this heat of the user is used. The reversible recording medium 100 is attached to the recording device 200b.
To insert. Then, the recording device 200b reads the optical information recorded on the recording layer 37 by the optical reading device 203 and sends it to the control device 300. When this optical information is, for example, recognition information of the owner of the thermoreversible recording medium 100, the thermoreversible recording medium 1 is controlled by the control device 300.
It is possible to confirm the correctness of the user of 00. Writing of information in the thermoreversible recording layer 25 and erasing of information in the thermoreversible recording layer can be performed by the same means as in the above (1).

(3) The thermoreversible recording medium 100 has, for example, the above-mentioned recording layer 37, for example, a recording layer capable of recording coded information and changing the information, such as a magnetic recording layer. In the case of the above, the user inserts the thermoreversible recording medium 100 into the recording device 200c.
Then, the recording device 200c causes the thermoreversible recording medium 100
The coded information recorded in the recording layer 37 of the control unit 30 is read by the read head 204.
Send to 0. Here, for example, the coded information can be, for example, balance information when the thermoreversible recording medium 100 is considered as a prepaid card, for example.

The control device 300 calculates a new balance from this balance information and the amount of money consumed by the user now, and further records this new balance in the recording layer 37 of the thermoreversible recording medium 100, and A command to display the thermoreversible recording layer 25 as visual information is sent to each of the recording devices 200c. The recording device 200c writes new balance information to the recording layer 37 by the recording head 205, and
To form the thermoreversible recording layer 25.

Of the thermoreversible recordings described above, the display is viewed from one side of the thermoreversible recording medium,
In the case of a type in which heat printing is performed from the other surface of the thermoreversible recording medium (for example, the thermoreversible recording medium shown in FIGS. 15 and 18), the thermal head 201 is provided so that characters can be normally seen on the visual side. Print signal of the controller 30
Must be adjusted at zero.

As is clear from the above description, the thermoreversible recording medium of the above-mentioned example is more suitable for recording and recording than the comparative example 1.
Since the decrease in contrast when erasing is repeated does not occur until at least 100 cycles, mechanical scratches are unlikely to occur. Further, as compared with Comparative Example 2, even if heating by recording / erasing is repeated, there is little warpage, and when used as a prepaid card in actual use, it will not be disabled due to warpage.

First to 18th Examples, Comparative Examples 1 and 2
Table 1 shows the transmittance and contrast after 100 cycles of recording / erasing of each sample, and the values in the long side and short side after 100 cycles of recording / erasing and the pencil hardness test method (JIS
The surface hardness determined by K5401) is summarized in Table 2.

[0093]

[Table 1]

[0094]

[Table 2]

According to the thermoreversible recording medium of the first aspect of the present invention, since polyvinyl acetal and organosiloxane (provided that they are crosslinked) are used as the protective layer material, the following effects 1 to 3 are obtained. (1) It is possible to obtain a thermoreversible recording medium in which a decrease in display contrast when recording and erasing are repeated is less likely to occur than in the past.

(2) It is possible to obtain a thermoreversible recording medium in which the temperature range in which the white turbid state can be formed and the temperature range in which the transparent state can be formed are both wider than in the past. Therefore, it is considered that the restriction on the temperature control of the thermal means such as the thermal head can be relaxed as compared with the conventional case. (3) When recording and erasing are repeated, the warp of the thermoreversible recording medium due to heating during erasing etc. can be reduced. Therefore, the thermoreversible recording medium suitable for repeated use when used in an actual card or the like. Is obtained.

[C] The second invention (thermoreversible recording apparatus) will be described. Next, an example of a thermoreversible recording device (hereinafter abbreviated as “recording device”) will be described. (1) First Embodiment of Second Invention FIG. 27 is a configuration diagram of a first embodiment of the second invention.

This recording apparatus is composed of a frame 61 and a heating element provided on the frame 61 for erasing the entire surface of the thermoreversible recording layer (see FIG. 1 etc.) of the thermoreversible recording medium. 63, the thermoreversible recording medium 100 provided so as to be in contact with the entire erasing tool 63, a writing tool 65 for forming a printing portion (image) on the thermoreversible recording medium 100, and a thermoreversible recording. A local erasing tool 67 for erasing a part of the image formed on the medium 100 and a temperature control section 69 for controlling the temperature of the overall erasing tool 63 are provided.

Here, the frame 61 can be made of a suitable material such as metal or resin according to the design of the recording apparatus. Further, the overall erasing tool 63 can be composed of a panel heater, for example. The entire eraser 63 is capable of applying a temperature according to the characteristics of the thermoreversible recording medium 100 (see FIG. 1, for example). The temperature control unit 69 that enables this can be configured by a conventionally known one.

As the thermoreversible recording medium 100, the one described in the embodiment of the first invention is used. Although not shown, the writing implement 65 includes a cylindrical main body, a head provided at the tip of the main body, a heat generating part built in the main body for heating the head, and a heat generating part. It has a power supply and a power switch. The head of the writing instrument 65 is
It is preferable to use a material having a good thermal conductivity, for example, a metal such as copper or a ceramic. Also, the shape of the head is
The tapered shape is preferable, but the thickness of the tapered shape is preferably determined in consideration of the size of characters to be drawn. Further, the heat generating portion can be composed of a resistance heating element such as a nichrome heater or a ceramic heater. The power source for the heat generating portion may be either a DC power source (including batteries) or an AC power source.

According to the recording apparatus of the first embodiment, when the full eraser 63 is operated according to the condition 13 of the thermal history of FIG. 1, the recording layer of the thermoreversible recording medium 100 becomes cloudy. When the writing tool 65 in the on state is brought into contact with the cloudy screen, the recording layer becomes transparent at the portion in contact with the cloudy screen, and the color of the colored support becomes transparent. In this case,
A red print area is obtained. As a result, an image composed of a white background portion and a red printing portion can be formed on the display body.
Further, when it is desired to erase only a part of the image, the image can be erased by bringing the local erasing tool 67 into contact with the part.

(2) Second Embodiment of Second Invention Also, FIG. 28 is an explanatory view of a second embodiment of the second invention.
The recording apparatus of the second embodiment is an example of an apparatus in which the thermoreversible recording medium 100 of the first invention is applied to the display surface of a display. More specifically, the thermoreversible recording medium 100 of the first invention, which has a band shape and a closed loop shape (hereinafter, also referred to as a loop medium 100a), holds the loop medium 100a, and when necessary. A first platen roll 206 and a second platen roll 2 for orbiting
07, a recording device 208 for recording information on the loop medium 100a and erasing information on the loop medium 100a, first and second platen rolls 206,
Control device 30 for controlling running / stopping and running speed of 207, and recording and erasing of the information by recording device 208.
1 is a device including. Here, the recording device 208 can be configured by the recording device 200a described with reference to FIG. 26, for example. Further, the control device can be configured by any suitable device using known print control technology and transport control technology.

The recording apparatus of the second embodiment can be used as, for example, an electronic bulletin board when the display is performed while moving the loop medium 100a. Further, if the thermoreversible recording medium is stopped at a proper time, it can be used as a bulletin board for predetermined information. The present invention is not limited to the above-mentioned embodiments, and various modifications can be made based on the spirit of the present invention, and these modifications are not excluded from the scope of the present invention.

[0104]

【The invention's effect】

(A) According to the first invention described in claims 1 to 10, as is clear from the above description, the thermoreversible recording medium of the example was repeatedly recorded and erased as compared with the comparative example 1. In this case, the decrease in contrast does not occur until at least 100 cycles, and thus mechanical scratches are unlikely to occur.

Further, as compared with Comparative Example 2, warpage is small even if heating by recording / erasing is repeated, and when used as a prepaid card in actual use, the warpage does not render the card unusable. In particular, according to the thermoreversible recording medium of the first aspect of the invention, since the protective layer material is polyvinyl acetal and organosiloxane (but crosslinked), the following effects 1 to 3 are obtained.

(1) It is possible to obtain a thermoreversible recording medium in which display contrast is less likely to deteriorate when recording and erasing are repeated than in the conventional case. (2) It is possible to obtain a thermoreversible recording medium in which the temperature range in which the white turbid state can be formed and the temperature range in which the transparent state can be formed are wider than in the past. Therefore, the restriction on the temperature control of the thermal means such as the thermal head can be relaxed as compared with the conventional case.

(3) When recording / erasing is repeated,
Since the warp of the thermoreversible recording medium due to heating during erasing or the like can be reduced, a thermoreversible recording medium suitable for repeated use can be obtained when used in an actual card or the like. (B) According to the second aspect of the invention, an image formed of a white background portion and a red printing portion can be formed on the display body. Further, when it is desired to erase only a part of the image, the image can be easily erased by bringing a local erasing tool into contact with the part.

When the display is performed while moving the loop medium, it can be used as an electronic bulletin board, for example. Moreover, when the thermoreversible recording medium is stopped at a proper time, it can be used as a bulletin board for predetermined information.

[Brief description of drawings]

FIG. 1 is a sectional view of a thermoreversible recording medium showing a first embodiment of the first invention.

FIG. 2 is a diagram showing characteristics of the thermoreversible recording material of the first invention.

FIG. 3 is a diagram showing a method for measuring the warp of the thermoreversible recording medium of the first invention.

FIG. 4 is a sectional view of a thermoreversible recording medium showing a nineteenth embodiment of the first invention.

FIG. 5 is a sectional view of a thermoreversible recording medium showing a twentieth embodiment of the first invention.

FIG. 6 is a sectional view of a thermoreversible recording medium showing a 21st embodiment of the first invention.

FIG. 7 is a sectional view of a thermoreversible recording medium showing a 22nd embodiment of the first invention.

FIG. 8 is a sectional view of a thermoreversible recording medium showing a 23rd embodiment of the first invention.

FIG. 9 is a sectional view of a thermoreversible recording medium showing a twenty-fourth embodiment of the first invention.

FIG. 10 is a sectional view of a thermoreversible recording medium showing a 25th embodiment of the first invention.

FIG. 11 is a sectional view of a thermoreversible recording medium showing a 26th embodiment of the first invention.

FIG. 12 is a sectional view of a thermoreversible recording medium showing a 27th embodiment of the first invention.

FIG. 13 is a sectional view of a thermoreversible recording medium showing a 28th embodiment of the first invention.

FIG. 14 is a sectional view of a thermoreversible recording medium showing a 29th embodiment of the first invention.

FIG. 15 is a sectional view of a thermoreversible recording medium showing a thirtieth embodiment of the first invention.

FIG. 16 is a sectional view of a thermoreversible recording medium showing a 31st embodiment of the first invention.

FIG. 17 is a sectional view of a thermoreversible recording medium showing a 32nd embodiment of the first invention.

FIG. 18 is a sectional view of a thermoreversible recording medium showing a 33rd embodiment of the first invention.

FIG. 19 is a sectional view of a thermoreversible recording medium showing a 34th embodiment of the first invention.

FIG. 20 is a sectional view of a thermoreversible recording medium showing a thirty-fifth embodiment of the first invention.

FIG. 21 is a sectional view of a thermoreversible recording medium showing a thirty-sixth embodiment of the first invention.

FIG. 22 is a sectional view of a thermoreversible recording medium showing a 37th embodiment of the first invention.

FIG. 23 is a sectional view of a thermoreversible recording medium showing a 38th embodiment of the first invention.

FIG. 24 is a sectional view of a thermoreversible recording medium showing a 39th embodiment of the first invention.

FIG. 25 is a sectional view of a thermoreversible recording medium showing a 40th embodiment of the first invention.

FIG. 26 is a diagram showing an example of use of the thermoreversible recording medium of the first invention.

FIG. 27 is a structural diagram of a recording apparatus using a thermoreversible recording medium showing a first embodiment of the second invention.

FIG. 28 is a configuration diagram of a recording apparatus using a thermoreversible recording medium showing a second embodiment of the second invention.

[Explanation of symbols]

20, 40, 50, 60, 70, 80, 90, 100,
101,110,120 Thermoreversible recording medium 21 Support 23 Reflective layer or light absorbing layer 25 Thermoreversible recording layer 29 Protective layer 31 Adhesive layer 33 Printing layer 35 Enhance layer 35a Air layer 37 Recording layer 39 Second protective layer 41 transparent support 51 plate-like body 51a end face 61 frame 63 overall erasing tool 65 writing tool 67 local erasing tool 69 temperature control section 100a loop medium 200a to 200c, 208 recording apparatus 201 thermal head 202 heating block (or heating roll) 203 optical reading device 204 reading head 205 recording head 206 first platen roll 207 second platen roll 300, 301 control device

 ─────────────────────────────────────────────────── ─── Continued front page (72) Fumio Nakagawa 1-7-12 Toranomon, Minato-ku, Tokyo Inside Oki Electric Industry Co., Ltd. (72) Hiroyo Kato 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (11)

[Claims] 1. A thermoreversible recording layer composed of a thermoreversible recording material which contains at least a matrix material and an organic low molecule and whose transparency changes with heat history, and a support for supporting the thermoreversible recording layer. In a thermoreversible recording medium having a protective layer on the side opposite to the support, either directly or via an intermediate layer, polyvinyl acetal and organosiloxane (however crosslinked) are used as the protective layer. A thermoreversible recording medium characterized by the above. 2. The thermoreversible recording medium according to claim 1, wherein the compounding ratio of polyvinyl acetal and organosiloxane (but crosslinked) used as the protective layer is 95: polyvinyl acetal: organosiloxane.
A thermoreversible recording medium, characterized in that it is 5 to 25:75. 3. The thermoreversible recording medium according to claim 1, wherein polyvinyl butyral is used as a matrix material in the thermoreversible recording material, and a group of saturated carboxylic acid and a derivative of the saturated carboxylic acid is used as an organic low molecule. A thermoreversible recording medium, characterized in that a material containing at least one selected is used. 4. The thermoreversible recording medium according to claim 1, wherein a matrix material containing polyvinyl acetal as a main component is used as a matrix material in the thermoreversible recording material, and a saturated carboxylic acid and the saturated organic acid are used as an organic low molecule. A thermoreversible recording medium comprising a material containing at least one selected from the group of carboxylic acid derivatives. 5. The thermoreversible recording medium according to claim 4, wherein the polyvinyl acetal is added with an epoxy resin, a phenol compound, an epoxy compound, an aldehyde compound, an isocyanic acid compound, an epoxy resin cured with a curing agent, and a curing agent. A thermoreversible recording medium, characterized in that an ultraviolet curable resin cured with an agent or a crosslinked organosiloxane is used. 6. The thermoreversible recording medium according to claim 1, wherein at least one of the support and the protective layer is made of a material transparent to visible light. 7. The thermoreversible recording medium according to claim 1, wherein when the intermediate layer is used, the intermediate layer is at least a reflective layer, a light absorbing layer, an enhancement layer and a printing layer to be a thermoreversible recording medium. A thermoreversible recording medium, characterized in that it is configured as one or more layers selected according to the light incident direction and the direction in which the recording formed by the thermoreversible recording medium is viewed. 8. The thermoreversible recording medium according to claim 1, wherein the support is made of a material having transparency to visible light, and the support is reflected on the side opposite to the thermoreversible recording layer. A thermoreversible recording medium comprising a layer or a light absorbing layer. 9. The thermoreversible recording medium according to claim 1, wherein the support has a property of changing a traveling direction of light incident on the support. recoding media. 10. The thermoreversible recording medium according to claim 1, further comprising a recording layer in addition to the thermoreversible recording layer. 11. A thermoreversible recording medium comprising a thermoreversible recording medium and a device for recording information on the thermoreversible recording medium and erasing information on the thermoreversible recording medium. A thermoreversible recording apparatus using the thermoreversible recording medium according to any one of claims 1 to 10.