JPH11277915A - Thermal reversible recording medium and card, and its production, and method and apparatus for processing image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal reversible recording medium which can extend width of temp. range where transparency occurs and provides enough transparency, i.e., enough contrast even when environmental temp. is changed and does not decrease erasing properties even by repeating printing and erasing. SOLUTION: In a thermal reversible recording medium provided with a heat- sensitive layer 13 wherein a resin matrix and an org. low mol. substance dispersed in the resin matrix are main ingredients and transparency reversibly changes with temp. on a substrate 11, as the org. low mol. substance, at least one of linear hydrocarbon-contg. compd. A contg. at least one of urea bonding, sulfonyl bonding and amide bonding and a carboxyl group and with a m.p. of lower than 130 deg.C and at least one of linear hydrocarbon-contg. compd. B with a m.p. being at least 20 deg.C lower than the m.p. of the linear hydrocarbon- contg. compd. A are mixed and used.

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, a card, and a thermoreversible recording medium capable of repeatedly forming and erasing an image by making use of a reversible change in transparency of a thermosensitive layer depending on the temperature. The present invention relates to a method for manufacturing a recording medium and a recording and erasing method and apparatus.

[0002]

2. Description of the Related Art In recent years, a thermoreversible recording medium having a heat-sensitive layer, in which a temporary image can be displayed and the image can be erased when it becomes unnecessary, and the transparency reversibly changes depending on the temperature, has attracted attention. ing. As a typical example, a thermoreversible recording medium in which an organic low-molecular substance such as a higher fatty acid is dispersed in a resin base material such as a vinyl chloride-vinyl acetate copolymer is known (JP-A-55-154198). No.). However, the conventional thermoreversible recording medium has a drawback that the temperature range showing light transmission and transparency is as narrow as 2 to 4 ° C., and an image is formed using light transmission / transparency and light shielding / white turbidity. In this case, there was difficulty in controlling the temperature.

In view of this point, the present inventors have disclosed in Japanese Patent Application Laid-Open Nos. 2-1363 and 3-19089 that a mixture of a higher fatty acid and an aliphatic dicarboxylic acid is used to make the mixture transparent. The temperature range was expanded to about 20 ° C., and it was clarified that the image could be easily erased (cleared). Further, in order to further improve the erasability, it has been proposed to use a mixture of a higher ketone or a fatty acid ester having a lower melting point than a higher fatty acid and an aliphatic dicarboxylic acid or a saturated aliphatic bisamide to widen a transparency temperature range ( JP-A-4-366682, JP-A-5-7754
9, Japanese Patent Application Laid-Open No. 5-294,062, Japanese Patent Application Laid-Open
255247). Although these have a wide range of clearing temperatures and improve erasability, they have large particles of several tens of μm or more inside the recording layer due to low solvent solubility, and have sufficient transparency even when heated to the clearing temperature. There was a disadvantage that it could not be obtained.

[0004]

SUMMARY OF THE INVENTION In view of the above situation, it is an object of the present invention to widen the temperature range for transparency, to obtain sufficient transparency even if the environmental temperature changes, and to obtain sufficient contrast. An object of the present invention is to provide a thermoreversible recording medium in which the erasability is not reduced even by repeated printing and erasing.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to provide (1) a resin base material and an organic low-molecular substance dispersed in the resin base material as main components on a support; In a thermoreversible recording medium provided with a heat-sensitive layer whose transparency reversibly changes depending on, as the organic low-molecular substance, a urea bond, a sulfonyl bond, a melting point of less than 130 ° C. having at least one of an amide bond and a carboxyl group. A mixture of at least one kind of the linear hydrocarbon-containing compound (A) and at least one kind of the linear hydrocarbon-containing compound (B) having a melting point lower than the melting point of the linear hydrocarbon-containing compound (A) by 20 ° C. or more is used. (2) "The thermoreversible recording medium according to the above (1), wherein the linear hydrocarbon-containing compound (A) has a melting point of 100 ° C. or more." ,
(3) "The linear hydrocarbon-containing compound (B) has a melting point of 50 ° C.
The thermoreversible recording medium according to the above (1) or (2), wherein the temperature is lower than 100 ° C.
(4) The above-mentioned (1) to (3), wherein the mixing ratio of the linear hydrocarbon-containing compound (A) and the linear hydrocarbon-containing compound (B) is 90:10 to 2:98. Wherein the thermoreversible recording medium according to any one of (1) to (5), wherein the (A) linear hydrocarbon-containing compound having a urea bond and a carboxyl group is used as the linear hydrocarbon-containing compound (A). (1) The thermoreversible recording medium according to any one of (4) to (4), and (6) a linear hydrocarbon-containing compound having a sulfonyl bond and a carboxyl group is used as the linear hydrocarbon-containing compound (A). The thermoreversible recording medium according to any one of the above (1) to (4), "
(7) The method according to any one of the above (1) to (4), wherein the compound (A) is a straight-chain hydrocarbon-containing compound having an amide bond and a carboxyl group. Thermoreversible recording medium ", (8)" the linear hydrocarbon-containing compound (B) is an aliphatic monocarboxylic acid, a fatty acid ester, a ketone having a higher alkyl group, a dibasic acid ester, a polyhydric alcohol difatty acid ester, The thermoreversible recording medium according to any one of (1) to (7), which is at least one selected from an aliphatic amide compound and an aliphatic urea compound. (1) to (8), wherein the material is crosslinked.
The thermoreversible recording medium described in any one of the above items ".

[0006] Further, the above object is attained by (10) of the present invention.
"A thermoreversible recording medium characterized in that it has a heat-sensitive layer and an information recording section according to any one of the above items (1) to (9) and is in the form of a card," (11) "the information recording section Is at least one selected from the group consisting of a magnetic recording layer, an IC, and an optical memory.

Another object of the present invention is to provide (12) the present invention, wherein “a resin base material and an organic low-molecular substance dispersed in the resin base material are mainly used on a support, and the transparency is reversible depending on temperature. In the method for producing a thermoreversible recording medium provided with a heat-sensitive layer that changes to, a dispersion of one or more organic low-molecular substances dispersed in a solid state in a resin solution is coated on a support, and dried by heating.
The method for producing a thermoreversible recording medium according to any one of (1) to (11), wherein the organic low-molecular substance dispersed during the heating and drying is dissolved in a dispersion solvent to form a thermosensitive layer. Is achieved.

Furthermore, the above object is achieved by the present invention,
3) “An image processing method for a thermoreversible recording medium in which an image is recorded and erased by heating using the thermoreversible recording medium according to any one of the above (1) to (11)”, (14) “ceramics” (13) The image processing method according to the above (13), wherein the image is erased by a heater.

Further, the above object is attained by the object (15) of the present invention.
"Image processing of a thermoreversible recording medium using the thermoreversible recording medium according to any one of the above (1) to (11) to record and erase an image by heating", (16) "Image processing by a ceramic heater" (1)
5) The image processing apparatus described in the item 5).

Further, the above object is achieved by the present invention,
7) The method according to any one of the above items (1) to (9), wherein an adhesive layer or a pressure-sensitive adhesive layer is provided on the surface of the support opposite to the surface on which the heat-sensitive layer is formed, and the support has a label shape. Thermoreversible recording medium ". Still further, the object is to form (18) the heat-sensitive layer according to any one of the above (1) to (9) on a disk or a package of the disk, or A disc with a reversible display and a disc package with a reversible display, wherein the label-like thermoreversible recording medium described above is attached.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The thermoreversible recording medium of the present invention utilizes the change in transparency (transparent state, cloudy opaque state) as described above. The difference between this transparent state and cloudy opaque state is presumed as follows.

(I) In the case of (i) transparent, the particles of the organic low-molecular substance dispersed in the resin base material are in close contact with the resin base material without any gap, and there are no voids in the particle portion, and there is no gap from one side. The incident light passes through to the opposite side without being scattered, so it looks transparent. (Ii) In the case of cloudiness, the particles of the organic low-molecular substance are polycrystals in which fine crystals of the organic low-molecular substance are aggregated. A gap is formed at the interface of the crystal or the interface between the particle and the resin base material, and the light incident from one side looks white because it is refracted, reflected, and scattered at the interface between the gap and the crystal, and the interface between the gap and the resin, etc. It is derived from.

FIG. 1 is a graph for easily explaining the temperature-transparency change in one example of the thermoreversible recording medium of the present invention.
In FIG. 1, a heat-sensitive layer mainly composed of a resin base material and an organic low-molecular substance dispersed in the resin base material is, for example, T _0.
It is cloudy and opaque at the following room temperature. As you heat it begins to gradually clear from the temperature T _1, the temperature T ₂ through T ₃
When heated to room temperature below T ₀ again, it remains transparent. It begins to resin softening from around the temperature T _1, as the softening proceeds, to reduce the voids in the interface or particles of the resin, for example, contracted resin and an organic low-molecular material particle, increases gradually transparency, temperature From T _{2 to} T ₃ , the organic low-molecular substance is in a semi-molten state, becomes transparent by filling the remaining voids with the molten organic low-molecular substance, and is cooled at a relatively high temperature by cooling while the seed crystal remains. It is considered that, at that time, the resin is still in a softened state, so that the resin does not follow a change in the volume of particles due to crystallization, so that no void is formed and the transparent state is maintained.

Further heating to a temperature above T ₄ results in a semi-transparent state intermediate between the maximum transparency and the maximum opacity. Next, when the temperature is lowered, the state returns to the original cloudy and opaque state without taking the transparent state again. After this the organic low molecular weight substance at a temperature T ₄ or more completely melted, becomes a supercooled state, is crystallized at a temperature slightly higher than T _0, this time, can not follow the volume change of the resin is caused by the crystallization, the gap It seems to be caused. However, the temperature shown in FIG.
The transparency change curve shows only a typical example, and the transparency of each state may change depending on the material by changing the material.

The reason that the erasability of the thermoreversible recording medium is deteriorated by the repetition of printing and erasing is that the internal structure of the recording layer changes due to the movement of the organic low-molecular substance melted by heating and moving in the resin. It seems to be caused by According to the present invention, it is possible to obtain a thermoreversible recording medium in which erasability does not decrease even when printing and erasing are repeated. The reason is presumed that the organic low-molecular substance has a polar group such as a urea bond, a sulfonyl bond, or an amide bond in the structure, so that adjacent low-molecular substances interact with each other and become difficult to move during heating and melting. You. However, organic low-molecular substances having only polar groups such as urea groups and amide groups and long-chain alkyl groups have low solvent melting properties, and therefore become large particles of the order of several tens of μm inside the recording layer. After cooling from ₄ , the super-cooled state is less likely to occur, voids are less likely to occur, and the contrast is reduced.

As described in the present invention, an organic low molecular weight substance having a carboxyl group in its structure in addition to a polar group such as a urea bond, a sulfonyl bond and an amide bond has an improved solvent melting property, and has a size of several μm or less inside the recording layer. Since fine particles are dispersed and present in the resin base material, a good contrast can be obtained, and both the improvement of the erasability and the high contrast can be achieved.

The linear hydrocarbon-containing compound (A) having at least one of a urea bond, a sulfonyl bond and an amide bond and a carboxyl group has a melting point of less than 130 ° C. The urea bond, the sulfonyl bond and the amide bond may have one or two or more of the same type in one molecule, or may be of different types, and may be at the terminal or the center of the molecule. The number of carboxyl groups may be one or more, and may be located at the terminal of the molecule or at the side chain. 130 ° C melting point
Above the above, there is a disadvantage that the turbidity temperature rises and the thermal sensitivity at the time of forming a turbid image decreases.

Further, a linear hydrocarbon-containing compound (A),
By mixing and using the linear hydrocarbon-containing compound (B) having a melting point lower by 20 ° C. than the melting point of the linear hydrocarbon-containing compound (A), it is possible to expand the transparentization temperature range. The straight chain hydrocarbon contained in the straight chain hydrocarbon-containing compound (A) or (B) may be saturated or unsaturated, and preferably has 2 to 30 carbon atoms, more preferably 4 to 22 carbon atoms. One or more hydrocarbon chains are contained in the same molecule. The total number of carbon atoms of all the linear hydrocarbons in one molecule is 4 to 60.
Is preferable, and 8-40 are more preferable.

The melting point of the linear hydrocarbon-containing compound (A) is 1
The temperature is preferably at least 00 ° C, more preferably at least 110 ° C.
If the melting point is too low, it is difficult to widen the temperature range for clearing.
The melting point of the linear hydrocarbon-containing compound (B) is 50 ° C. or higher and 10
Preferably it is below 0 ° C. This melting point is preferably 60 ° C. or higher, particularly preferably 70 ° C. or higher, and further preferably 90 ° C. or lower. If the melting point is too low, the heat resistance of the image decreases, and if it is too high, it is not possible to increase the transparent temperature range.

The mixing ratio between the linear hydrocarbon-containing compound (A) and the linear hydrocarbon-containing compound (B) is 90:10 to 2:98.
Is preferred. As for this mixing ratio, the ratio of the linear hydrocarbon-containing compound (B) is more preferably 95 or less, particularly preferably 90 or less, further preferably 30 or more, particularly preferably 40 or more, and more preferably 50 or more. Each of the linear hydrocarbon-containing compounds (A) and (B) may be a single type or a mixture of two or more types. Linear hydrocarbon-containing compound (B)
If the ratio is too high, the transparency on the low temperature side becomes high even in the range of the temperature for making the film transparent, and the transparency on the high temperature side becomes low. On the other hand, if the ratio of the linear hydrocarbon-containing compound (B) is too low, sufficient transparency cannot be obtained.

The following are examples of the linear hydrocarbon-containing compound (A) having a urea bond and a carboxyl group represented by the general formula (1):
However, the present invention is not limited thereto.

[0022]

Embedded image CH ₃ (CH ₂ ) m-NHCONH— (CH ₂ ) n-COOH General formula (1) (wherein, m represents an integer of 0 to 25 and n represents an integer of 1 to 25, respectively. M) + n is preferably 10 or more, and more preferably 15 or more. Examples of the substance represented by the general formula (1) include the following.

[0023]

[Table 1]

The following are examples of the linear hydrocarbon-containing compound (A) having a sulfonyl bond and a carboxyl group, which are represented by the general formula (2), but are not limited thereto.

[0025]

Embedded image CH ₃ (CH ₂ ) m-SO ₂ — (CH ₂ ) n-COOH General formula (2) (wherein, m represents an integer of 0 to 25, and n represents an integer of 1 to 25, respectively) .) M + n is preferably 10 or more, and more preferably 15 or more. Examples of the substance represented by the general formula (2) include the following.

[0026]

[Table 2]

Examples of the linear hydrocarbon-containing compound (A) having an amide bond and a carboxyl group include, but are not limited to, those represented by the following general formula (3).

[0028]

Embedded image CH ₃ (CH ₂ ) m-CONH— (CH ₂ ) n-COOH General formula (3) (in the formula, m represents an integer of 0 to 26, and n represents an integer of 1 to 25, respectively). M) + n is preferably 10 or more, and more preferably 15 or more. Examples of the substance represented by the general formula (3) include the following.

[0029]

[Table 3]

Examples of the compound (A) having a straight chain hydrocarbon having an amide bond and a carboxyl group include, but are not limited to, those represented by the following general formula (4).

[0031]

CH ₃ (CH ₂ ) m-NHCO- (CH ₂ ) n-COOH General formula (4) (wherein m represents an integer of 0 to 25, and n represents an integer of 1 to 26, respectively) M) + n is preferably 10 or more, and more preferably 15 or more. Examples of the substance represented by the general formula (4) include the following.

[0032]

[Table 4]

Examples of the compound (A) having a straight chain hydrocarbon having an amide bond and a carboxyl group include, but are not limited to, a compound represented by the following general formula (5).

[0034]

HOCO- (CH ₂ ) m-NHCO- (CH ₂ ) n-COOH General formula (5) (wherein m represents an integer of 1 to 25, and n represents an integer of 1 to 26, respectively) M) + n is preferably 10 or more, and more preferably 15 or more. Examples of the substance represented by the general formula (5) include the following.

[0035]

[Table 5]

Examples of the linear hydrocarbon-containing compound (B) include aliphatic monocarboxylic acids, fatty acid esters, ketones having higher alkyl groups, dibasic acid esters, polyhydric alcohol difatty acid esters, aliphatic amide compounds, Examples include, but are not limited to, aliphatic urea compounds.

The following are more specific examples, but the present invention is not limited to these examples. That is, specific examples of the aliphatic monocarboxylic acid include, for example, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid,
Examples include margaric acid, stearic acid, nonadecyl acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, and melicic acid.

Specific examples of fatty acid esters include octadecyl laurate, docosyl laurate, docosyl myristate, dodecyl palmitate, tetradecyl palmitate, pentadecyl palmitate, hexadecyl palmitate, octadecyl palmitate, triacontyl palmitate, palmitate Octadecyl acid,
Docosyl palmitate, vinyl stearate, propyl stearate, isopropyl stearate, butyl stearate, amyl stearate, heptyl stearate, octyl stearate, tetradecyl stearate, hexadecyl stearate, heptadecyl stearate, octadecyl stearate, stearic acid Docosyl, hexacosyl stearate, triacontyl stearate, dodecyl behenate, octadecyl behenate, docosyl behenate, trakosyl lignocerate, myricyl melysinate and the like.

Specific examples of ketones having a higher alkyl group include, for example, 8-pentadecanone, 9-heptadecanone, 10-nonadecanone, 11-heneicosanone,
12-trichosanone, 14-heptacosanone, 16-hentriacontanone, 18-pentatriacontanone,
22-tritetracontanone, 2-pentadecanone, 2
-Hexadecanone, 2-heptacanone, 2-octadecanone, 2-nonadecanone and the like.

The dibasic acid ester may be either a monoester or a diester, and is represented by the following general formula (6).

[0041]

[Image Omitted] ROOC- (CH ₂ ) n -COOR ′ General formula (6) (wherein R and R ′ represent a hydrogen atom or an alkyl group having 1 to 30 carbon atoms; R ′ may be the same or different, but excludes the case where they are hydrogen atoms at the same time, and n represents an integer of 0 to 40) In the dibasic acid ester represented by the general formula (6), , R ′ preferably have 1 to 22 carbon atoms, n has preferably 1 to 30, and more preferably 2 to 20 carbon atoms.

Specifically, succinic diester, adipic diester, sebacic diester, 1- or 18
-Octadecamethylene dicarboxylic acid ester and the like.

The polyhydric alcohol difatty acid ester of the organic low molecular weight substance used in the present invention is represented by the following general formula (7):
Are represented.

[0044]

Embedded image CH ₃ (CH ₂ ) m- ₂ COO (CH ₂ ) nOOC (CH ₂ ) m- ₂ CH ₃ ... General formula (7) (wherein n is 2 to 40, preferably 3 to 30, more preferably an integer of 4 to 22. m is an integer of 2 to 40, preferably 3 to 30, more preferably 4 to 22.) Specific examples include the following. 1,3 propanediol dialkanate, 1,6 hexanediol dialkanate, 1,10 decanediol dialkanate, 1,18 octadecanediol dialkanate.

Specific examples of the aliphatic amide compound include, for example, those represented by the following general formula (8).

[0046]

Embedded image R ¹ —CONH—R ² ... General formula (8) (where R ¹ is a straight chain hydrocarbon having 1 to 25 carbon atoms, R ² is hydrogen, and 1 to 26 carbon atoms) It is a straight-chain hydrocarbon chain or a methylol group, and at least ^one of R ¹ and R ² is a straight-chain hydrocarbon having 8 or more carbon atoms.)

Examples of these include nonanamide, decanamide, undecaneamide, dodecaneamide, tridecaneamide, tetradecaneamide, hexadecaneamide, octadecanamide, eicosanamide, docosamide, tricosamide, hexacosamide, octacosamide, oleic acid Amide, erucamide or N
-Lauryl lauric acid amide, N-palmityl palmitic acid amide, N-stearyl stearic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, N -Oleyl palmitic acid amide, N-12 hydroxystearyl stearic acid amide, N-12 hydroxystearyl oleic acid amide and the like.

Specific examples of the aliphatic urea compound include, for example, those represented by the following general formula (9).

[0049]

Embedded image R ³ —NHCONH—R ⁴ ... General formula (9) (where R ³ and R ⁴ are hydrogen or a straight-chain hydrocarbon having 1 to 26 carbon atoms, and at least one of them) Is a straight-chain hydrocarbon having 8 or more carbon atoms.) Examples of these are N-butyl-N′-stearyl urea, N-phenyl-N′-stearyl urea, N-stearyl-N′-stearyl urea and the like. Is mentioned.

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

It is preferable to crosslink these resins.
The repeated durability of the crosslinked medium is improved. In the case of crosslinking, the resin preferably has a functional group such as a hydroxy group, a carboxy group, or an epoxy group. As a method of crosslinking, there is a method by thermal crosslinking, irradiation of UV or EB,
It is preferable to perform crosslinking by adding an isocyanate or various acrylic crosslinking agents. Glass transition temperature of resin matrix is 60 ° C
Or higher, more preferably 70 ° C. or higher. 100
C. or lower, more preferably 90.degree. C. or lower. As the glass transition temperature increases, the image heat resistance further improves.

The thickness of the heat-sensitive layer of the thermoreversible recording medium of the present invention is preferably from 1 to 30 μm, more preferably from 2 to 20 μm. 6-18 μm is particularly preferred. If the recording layer is too thick, heat distribution will occur in the layer, making it difficult to achieve uniform transparency. On the other hand, if the heat-sensitive layer is too thin, the turbidity decreases and the contrast decreases. The turbidity can be increased by increasing the amount of the fatty acid in the recording layer. The ratio between the organic low-molecular substance and the resin (the resin having a crosslinked structure) in the heat-sensitive layer is preferably about 2: 1 to 1:16 by weight,
1: 2 to 1: 8 is more preferable, 1: 2 to 1: 5 is particularly preferable, 1: 2 to 1: 4 is more preferable, and 1: 2 to 1: 2 is more preferable.
1: 3.5 is more preferred. If the ratio of the resin is less than this, it becomes difficult to form the organic low-molecular substance in the film held in the resin, and if it is more than this, it becomes difficult to make the film opaque because the amount of the organic low-molecular substance is small. .

Further, a protective layer can be provided on the heat-sensitive layer to protect the heat-sensitive layer. Examples of protective layer (0.1 to 5 μm thick) materials to be laminated on the heat-sensitive layer include silicone rubber, silicone resin (described in JP-A-63-221087), and polysiloxane graft polymer (Japanese Patent Application No. 62-210). No. 152550) and ultraviolet curable resin or electron beam curable resin (described in Japanese Patent Application No. 63-310600).
And the like. These may contain an organic or inorganic filler.

Further, an intermediate layer can be provided between the protective layer and the heat-sensitive layer in order to protect the heat-sensitive layer from a solvent, a monomer component, and the like of the protective layer forming solution (Japanese Patent Laid-Open No. 1-133).
No. 781). As the material of the intermediate layer, the following thermosetting resins, thermoplastic resins, UV-curing resins, and EB-curing resins can be used in addition to those listed as the resin base material in the thermosensitive layer. That is, polyethylene, polypropylene, polystyrene, polyvinyl alcohol, polyvinyl butyral, polyurethane, saturated polyester, unsaturated polyester, epoxy resin, phenol resin, polycarbonate, polyamide and the like can be mentioned. The thickness of the intermediate layer is preferably about 0.1 to 2 μm. Below this, the protective effect is reduced, and above this, the thermal sensitivity is reduced.

The object of the present invention is to provide a heat-sensitive layer having, as a main component, a resin base material and an organic low-molecular substance dispersed in the resin base material, and the transparency of which changes reversibly depending on the temperature. In the method for producing a thermoreversible recording medium provided with, a dispersion in which one or more organic low-molecular substances are dispersed in a solid state in a resin solution is coated on a support, dried by heating, and dispersed at the time of the heating and drying. This is achieved by a method for producing a thermoreversible recording medium, wherein a low-molecular organic substance is dissolved in a dispersion solvent to form a thermosensitive layer.

The organic low molecular weight substance used has a melting point of 20.
It is preferable to use a mixture of two or more kinds different from each other by at least ° C. As the melting point of an organic low-molecular substance increases, it becomes difficult to dissolve it in an ordinary solvent at normal temperature. Disperse organic low-molecular substances that are difficult to dissolve in these solvents,
When the coating is dissolved during heating and drying, the same structure as before (the organic low-molecular substance is dispersed in spherical fine particles in the resin) is obtained when the coating is formed by dissolving in a solvent at room temperature. And the organic low molecular weight substance is
When more than one kind is used, a reversible thermosensitive recording material having a wide transparency temperature range, a large contrast between the transparent state and the opaque state, and easy temperature control for repeatedly generating the transparent state and the opaque state is obtained. be able to.

The solvent used may be a mixture of two or more solvents, and at least one of the solvents has a high boiling point,
Particularly, it is preferable to use a solvent having a boiling point of 100 ° C. or higher, whereby a reversible thermosensitive recording material having a higher contrast between the transparent state and the opaque state can be obtained.

Further, the content of the solvent having a high boiling point in the mixed solution is particularly preferably at least 10% by weight of the total solvent in the mixed solution, whereby the organic matrix in the form of a resin matrix or two or more organic low-molecular substances coexist. The low-molecular substance domain shape is spherical, elliptical, or rounded, whereby a reversible thermosensitive recording material capable of repeatedly producing a transparent state and an opaque state with a large contrast many times can be obtained.

In the case where the above-mentioned method for producing a reversible thermosensitive recording material is preferably applied, the drying temperature for applying and drying the mixed solution on a support as the organic low-molecular substance in the above-mentioned dispersion is described. Is a case where an organic low-molecular substance soluble in a dispersion solvent is used. 0.5% especially for dispersion solvent
It is preferable to use an organic low-molecular substance that dissolves as described above.
Further, at room temperature, the solubility of the organic low-molecular substance dispersed in the dispersion liquid in the dispersion liquid solvent is preferably less than 0.5%. Dispersion particle size of organic low molecular substance is 50μm
Or less, more preferably 30 μm or less.

By using such an organic low-molecular-weight substance, the organic low-molecular-weight substance is once dissolved in a solvent at the time of drying, and undergoes a phase separation process so that two or more organic low-molecular-weight substances in the dispersion coexist. A molecular substance domain is formed.

The object of the present invention is to provide a heat-sensitive layer comprising a resin base material and an organic low-molecular substance dispersed in the resin base material as a main component and having a transparency that reversibly changes depending on the temperature. In the method for producing a thermoreversible recording medium provided with, a dispersion in which one or more organic low-molecular substances are dispersed in a solid state in a resin solution is coated on a support, and has a highest melting point in the heat-sensitive layer. Thermoreversible characterized by heating and drying at a temperature lower than the melting point of the low molecular weight organic substance to form a thermosensitive layer, and then heating the thermosensitive layer above the melting point of all the low molecular weight organic substances in the thermosensitive layer This is achieved by a method for manufacturing a recording medium.
It is preferable that two or more kinds of organic low-molecular substances used differ in melting point from each other by 20 ° C. or more.

The organic low-molecular-weight substance dispersion liquid is coated on a support and dried to form a reversible thermosensitive recording layer. Then, the reversible thermosensitive recording layer is heated at a temperature equal to or higher than the melting point of the organic low-molecular-weight substance. By applying, a reversible thermosensitive recording material having a wide range of transparency temperature, high contrast between the transparent state and the opaque state, and easy temperature control for repeatedly generating the transparent state and the opaque state can be obtained. This is because by performing a heat treatment on the reversible thermosensitive recording layer, two or more types of organic low-molecular substances each independently dispersed in the resin matrix in the reversible thermosensitive recording layer are melted, thermally expanded, This is due to the formation of an organic low molecular substance domain in which two or more types of organic low molecular substances coexist due to the softening of the resin.

By subjecting the reversible thermosensitive recording layer to heat treatment at a temperature not lower than the melting point of the organic low-molecular substance, the shape of the resin matrix or the domain shape of the organic low-molecular substance in which two or more organic low-molecular substances coexist is obtained. It becomes spherical, elliptical or rounded, thereby obtaining a reversible thermosensitive recording material capable of repeatedly producing a transparent state and an opaque state with a large contrast many times. It is particularly preferable that the number of the resin matrix shape or the organic low-molecular substance domain shape having a spherical, elliptical or round shape is 10% or more of the total resin matrix number or the total organic low-molecular substance domain number. In these production methods, when two or more organic low molecular weight substances are used, for example, one kind may be used in dispersion, and one kind may be used after being dissolved in a solvent even at room temperature.

Further, it is preferable to provide a coloring layer in addition to the reversible thermosensitive layer and to have a reversible thermosensitive layer thereon to make the reversible visible image easily visible. In this case, the coloring layer may be composed of two or more types of portions having different reflectances with respect to visible light.

By providing both the reversible displayable thermosensitive layer satisfying the above three conditions and the information storage section on the same card, a part of the information stored in the information storage section is displayed on the thermosensitive layer. In addition, the card holder can check the information only by looking at the card without any special device, and the convenience is improved. The information storage unit may be anything that can store necessary information, but magnetic recording, IC, and optical memory are preferable. Further, the reversible thermosensitive material used for display may be used for the storage unit by a barcode, a two-dimensional code, or the like. Among them, magnetic recording and IC are more preferable.

In particular, when the reversible recording medium of the present invention is provided with a rewritable barcode, it is preferable that the medium comprises two or more portions having different reflectivities. This is because, when viewed by a human, for example, there is a color tone difference between the image portion in the cloudy state and the non-image portion in the colored state in addition to the difference in the amount of light, and depending on the viewing angle, there is excessive The glare caused by reflected light is eliminated, making it easier to see a reversible visible image.On the other hand, when reading this image with a device such as a reflection densitometer or a bar code reader, light is normally incident obliquely. The sensor is placed and read in the direction perpendicular to the plane, because the colored layer absorbs at least a part of the visible light and lowers the contrast to measure the result. Thus, the colored layer in the reversible thermosensitive recording medium of the present invention is composed of two or more types of portions having different reflectances to visible light, and at least one of the portions is a layer that absorbs visible light. Is formed of a layer that reflects visible light at least in part, so that an image can be easily recognized visually and a high contrast can be obtained even when measured by an apparatus.

To obtain the high contrast required to read barcodes in a reversible (reversible) thermosensitive layer,
The average particle size of the organic low molecular weight substance is preferably in the range of 0.1 to 2.0 μm, and the opacity becomes more appropriate. And, as the average particle size of the dispersed organic low-molecular substance increases, it becomes difficult to be in a polycrystalline state, the effect of scattering light decreases, the opacity decreases, the contrast decreases, and conversely, The smaller the average particle size of the dispersed organic low molecular weight material becomes, the more difficult it becomes to form a polycrystalline state in the dispersed matrix during crystal growth, and also in this case, the turbidity decreases and the contrast decreases. Conceivable. Further, when reading the barcode, when the average particle diameter of the particles of the organic low-molecular substance is in the range of 1/8 to 2 times the wavelength of the light source at the time of reading the barcode, the contrast at the time of reading the barcode. Is further improved. It is not yet clear why these phenomena occur, but it is speculated as follows. That is, the degree of turbidity, that is, the degree of light scattering, is considered to be determined by the size of the crystal in the organic low-molecular substance particles, and the size of the crystal is considered to be determined by the size of the organic low-molecular substance particles. This is because the area of the interface between the resin base material and the organic low-molecular substance dispersed in the resin base material is determined by the size of the low-molecular substance particles, and the resin base material and the organic low-molecular substance are determined from the area of this interface. It is speculated that the strength of the interaction with the molecular substance is determined and that the strength of the interaction affects the size of the crystals in the particles. In addition, there is a size of a crystal that is most likely to scatter light of a certain wavelength, which varies depending on each material. However, a crystal smaller than the wavelength of light tends to scatter light of that wavelength. That is, the average particle diameter of the organic low-molecular substance is が of the wavelength of the light for reading the barcode.
It is considered that the size of each of the polycrystals in the low-molecular-weight organic low-molecular substance particles in the cloudy state is the size that most easily scatters light of that wavelength when the range is from 2 to 2. . The above average particle diameter is 1/1 of the wavelength of the reading light source.
When it is less than 8, the scattering effect decreases, the cloudiness decreases,
Contrast decreases. Conversely, when the contrast exceeds twice, the surface area of the interface between the resin base material and the organic low-molecular substance decreases, the interaction between the resin base material and the organic low-molecular substance decreases, and the organic low-molecular substance particles are reduced. It is thought that it becomes difficult to control the crystal inside,
The turbidity decreases and the contrast decreases. As a method for controlling the particle size of the organic low-molecular substance, mixing of a poor solvent, control of drying by heating at the time of coating the recording layer forming liquid, addition of a surfactant for controlling dispersibility, and the like can be considered. It is not limited to these.

By the way, the wavelength of a light source for reading a bar code is conventionally defined to be 600 nm or more (JIS B).
9550), and a light source having a wavelength in the range of 600 nm to 1000 nm is usually used. Specifically, LED (66
0 nm and 940 nm wavelengths are often used), laser (He-Ne laser at 600 nm, semiconductor laser at 680 nm, 780 nm and 960 n)
m is often used).

According to the bar code display of the reversible recording medium of the present invention, it is of course possible to read a bar code using a light source having a wavelength of 660 nm or more as described above. Alternatively, a shorter wavelength light source can provide higher contrast. For example, when light of 400 to 600 nm is used, the contrast is at most twice as high as that of light of 600 to 10,000 nm. This is presumably because light having a shorter wavelength has a higher refractive index with respect to the organic low-molecular-weight substance, increases light scattering, and therefore improves turbidity.

The "bar code" used here is not limited as long as optical changes such as light intensity and wavelength change can be recognized as information regardless of whether it is in the visible light wavelength region. Therefore, other optical recognition pattern displays represented by two-dimensional barcodes, OCR and Carla codes are also included.

Further, in the reversible recording medium of the present invention, by providing the magnetic recording layer, a part of the magnetically recorded information can be displayed on the heat-sensitive layer. improves. As the magnetic recording layer, usually used iron oxide, barium ferrite and the like, and a PVC-based or urethane-based resin or the like are used, and are formed on the support by coating, or are formed without using a resin by a method such as evaporation or sputtering. . The magnetic storage unit may be provided on the surface of the support opposite to the heat-sensitive layer, or may be provided between the support and the heat-sensitive layer or on a part of the heat-sensitive layer. It is also possible that the magnetic recording layer also serves as a colored layer. However, the reversible recording medium used in the present invention includes barcode information, magnetic recording information, IC, optical memory,
It is not always necessary to provide information storage using a magneto-optical memory or the like.

Therefore, for example, as shown in FIG. 2A, the reversible thermosensitive recording medium of the present invention is a film comprising a support (11) provided with a reversible thermosensitive recording layer (13) and a protective layer (14). , As shown in FIG.
1) A film having an aluminum reflective layer (12), a reversible thermosensitive recording layer (13), and a protective layer (14) provided thereon, FIG.
c, an aluminum reflective layer (12), a reversible thermosensitive recording layer (13), and a protective layer (1) on a support (11).
4) providing a magnetic recording layer (16) on the back surface of the support (11);
As shown in FIG. 3, the film provided with may be processed into a card (21) having a print display section (23).

Further, for example, as shown in FIG.
A film formed by providing an aluminum reflective layer (12), a reversible thermosensitive recording layer (13), and a protective layer (14) on a support (11) is processed into a card shape, and a depression (2) for accommodating an IC chip is formed.
3) can be formed and processed into a card shape. In this example, a rewritable recording section (24) is label-processed on a card-like reversible thermosensitive recording medium, and a recess (23) for embedding an IC chip is provided at a predetermined location on the back side of the reversible thermosensitive recording medium. In this recess (23), a wafer (231) as shown in FIG. 4b is assembled and fixed. Wafer (23
1) an integrated circuit (233) on a wafer substrate (232)
And a plurality of contact terminals (234) electrically connected to the integrated circuit (233) are provided on the wafer substrate (232). The contact terminals (234) are exposed on the back side of the wafer substrate (232), and a dedicated printer (reader / writer) electrically contacts the contact terminals (234) to read or rewrite predetermined information. It is configured to be able to. An example of the function of the reversible thermosensitive recording card will be described with reference to FIG.

FIG. 5A is a schematic block diagram showing an integrated circuit (233), and FIG. 5B is a block diagram showing an example of data stored in a RAM. Integrated circuit (2
33) includes, for example, an LSI, and includes a CPU capable of executing a control operation in a predetermined procedure.
(235), a ROM (236) for storing operation program data of the CPU (235), and a RAM (237) for writing and reading necessary data. Further, the integrated circuit (233) receives the input signal and
(235) and the CPU (23).
5) an input / output interface (238) for receiving an output signal from the device and outputting the signal to the outside, a power-on reset circuit, a clock generator, a pulse divider (interrupt pulse generator), and an address decoder (not shown) Including circuits. The CPU (235) can execute the operation of the interrupt control routine in accordance with the interrupt pulse periodically given from the pulse dividing circuit. The address decode circuit decodes the address data from the CPU (235) and provides signals to the ROM (236), the RAM (237), and the input / output interface (238).
A plurality of (eight in the figure) contact terminals (234) are connected to the input / output interface (238), and predetermined data from the dedicated printer (reader / writer) is input from the contact terminals (234). Output interface (2
38) to the CPU (235). CPU
(235) responds to the input signal and outputs the data from the ROM (23)
According to the program data stored in 6), each operation is performed, and predetermined data and signals are output to the card reader / writer via the input / output interface (238).

As shown in FIG. 5B, the RAM (2
37) includes a plurality of storage areas (239a) to (239f). For example, the area (239a) stores a card number, and the area (239b) stores ID data such as the name, address, and telephone number of the card owner.
In c), for example, information corresponding to the residual value or valuable material usable by the owner is stored, and the area (239d) (2)
39e) (239f) and (239g) store information corresponding to used valuables or valuables.

The method and apparatus for recording and erasing an image on the thermoreversible recording medium will be described below. For recording an image, an image recording means, such as a thermal head or a laser, capable of partially heating the medium on the image is used. For image erasing, an image erasing means such as a hot stamp, a ceramic heater, a heat roller, hot air, a thermal head, a laser, or the like is used. Among them, a ceramic heater is preferably used. By using the ceramic heater, the size of the apparatus can be reduced, a stable erased state can be obtained, and an image with good contrast can be obtained. The set temperature of the ceramic heater is preferably at least 90 ° C, particularly preferably at least 100 ° C.

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

FIG. 6 shows a specific example of the thermoreversible recording apparatus of the present invention. FIG. 6a shows a schematic example of an apparatus for erasing an image using a ceramic heater and forming an image using a thermal head according to the present invention. In the thermoreversible recording device of FIG. 6A, first, information stored in a magnetic recording layer of a recording medium is read by a magnetic head, and then an image recorded on the reversible thermosensitive layer is heated and erased by a ceramic heater.
Furthermore, based on the information read by the magnetic head,
The processed new information is recorded on the reverse thermosensitive layer by the thermal head. Thereafter, the information in the magnetic recording layer is also rewritten with new information.

That is, in the thermoreversible recording apparatus of FIG. 6A, the thermoreversible recording medium (1) provided with the magnetic recording layer on the opposite side of the thermosensitive layer moves along the transport path shown by the reciprocating arrow. It is conveyed or conveyed in the reverse direction in the apparatus along the conveyance path. The thermoreversible recording medium (1) is magnetically recorded or erased on the magnetic recording layer between the magnetic head (34) and the transport roller (31), and the image is erased between the ceramic heater (38) and the transport roller (40). For this reason, a heat treatment is performed, an image is formed between the thermal head (53) and the transport roller (47), and thereafter, it is carried out of the apparatus. As described above, the set temperature of the ceramic heater (38) is preferably 100 ° C. or higher, more preferably 105 ° C. or higher. However, rewriting of magnetic recording may be performed before or after image erasure by the ceramic heater. Also, if desired,
After passing between the ceramic heater (38) and the transport roller (40), or after passing through the thermal head (53) and the transport roller (4).
7), the sheet is conveyed in the conveying path in the reverse direction, and can be subjected to another heat treatment by the ceramic heater (38) and another printing process by the thermal head (53).

In the thermoreversible recording apparatus shown in FIG. 6B, the thermoreversible recording medium (1) inserted from the entrance (30) advances along the transport path (50) shown by a dashed line, or It travels in the device in the reverse direction along the transport path (50). The thermoreversible recording medium (1) inserted from the entrance (30) is transported by the transport roller (31) and the guide roller (3).
When the sheet is conveyed through the recording apparatus by the method (2) and reaches a predetermined position on the conveyance path (50), the sensor (33) controls the control means (3).
4c), the presence of which is recognized, and the magnetic head (3
4) and the platen roller (35) are magnetically recorded or erased on the magnetic recording layer, pass between the guide roller (36) and the transport roller (37), and pass between the guide roller (39) and the transport roller (40). After passing through, the sensor (43) recognizes the presence thereof through the ceramic heater control means (38c) and heat-processes between the ceramic heater (38) and the platen roller (44) for erasing an image.
The transport path (5) is transported by the transport rollers (45), (46) and (47).
0), and is formed at a predetermined position between a thermal head (53) and a platen roller (52) which operate by recognizing the presence thereof via a thermal head control means (53c) by a sensor (51). And the transport path (50a)
From the apparatus through an outlet (61) by a transport roller (59) and a guide roller (60). Here, as described above, the set temperature of the ceramic heater (38) is preferably 100 ° C. or higher, and more preferably 105 ° C. or higher.

If desired, the transfer path switching means (55
a) is led to the transport path (56b) by switching
The thermoreversible recording medium (1) is again moved to the thermal head (53) and the platen by the transport belt (58) that moves in the opposite direction to the operation of the limit switch (57a) input by pressing the thermoreversible recording medium (1). After the heat treatment between the rollers (52), the sheet is transported in the forward direction via a transport path (49b), a limit switch (57b), and a transport belt (48) which are opened by switching the transport path switching means (55b). From (50a), it can be carried out of the apparatus via the outlet (61) by the conveying roller (59) and the guide roller (60). Further, such a branched transport path and transport switching means can be provided on both sides of the ceramic heater (38), in which case the sensor (43a)
Is preferably provided between the platen roller (44) and the transport roller (45). In these devices, a heat insulating cover can be provided around the thermal head (53) so that the magnetic recording layer and the like are not affected by heat from the ceramic heater (38).

In the thermoreversible recording medium of the present invention, an adhesive layer or a pressure-sensitive adhesive layer can be provided on the surface of the support opposite to the surface on which the heat-sensitive layer is formed. By providing the adhesive layer or the pressure-sensitive adhesive layer in this manner, the recording layer can be stuck on the entire surface or a part of a thick substrate such as a magnetic card with a magnetic stripe where application of the recording layer is difficult. The convenience of this medium is improved, for example, a part can be displayed.

The thermoreversible recording label provided with such an adhesive layer or pressure-sensitive adhesive layer is not limited to the above-mentioned PVC card,
Not only can it be applied to thick cards such as IC cards and optical cards, but it can also be used as a substitute for display labels on floppy disks, video tapes, mini disks, etc., and the display contents are automatically changed in response to changes in their stored contents. It is possible to apply to the use of. A label can be directly applied to a disc on a CD-rewritable disc or the like, and a thermoreversible recording layer can be formed on the disc by coating or transferring. Further, a release paper may be provided on the adhesive layer or the pressure-sensitive adhesive layer. As the release paper to be used, commercially available silicone paper is preferable.

The heat-sensitive recording layer of the reversible heat-sensitive recording label of the present invention is repeatedly sandwiched between the thermal head and the platen when forming and erasing an image with a thermal head or the like. Conveyed by
Therefore, if the adhesive strength when the label sheet is adhered to the adherend is insufficient, the label sheet may be peeled off during repeated image formation and erasing. Therefore, in the present invention, when the adhesive strength between the label sheet and the adherend is represented by JIS K-6854, the average value of the tensile load measured by the 180-degree peeling method, 0.5
kgf / 25 mm or more is preferable. In the case of a configuration in which the support side of the reversible thermosensitive recording label is bonded to paper or film, it is desirable that the adhesive force between the support and the paper or film is 0.5 kgf / 25 mm or more. That is, as the adhesive layer or the pressure-sensitive adhesive layer, the adhesive strength when bonded to the adherend is JIS K-68.
It can be said that it is preferable to select a material having a tensile load of 0.5 kgf / 25 mm or more when represented by the average value of the tensile loads measured by the method of peeling at 54 and 180 degrees. As the adhesive, a heat-adhesive adhesive which exhibits adhesiveness when heated may be used.

Specific examples of the adhesive and the pressure-sensitive adhesive include, for example, urea resin, melamine resin, phenol resin, epoxy resin, vinyl acetate resin, vinyl acetate acrylic copolymer resin, EVA resin, acrylic resin, polyvinyl resin Ether resin, vinyl chloride vinyl acetate copolymer resin, polystyrene resin, polyester resin, polyurethane resin, polyamide resin, chlorinated polyolefin resin, polyvinyl butyral resin, acrylate copolymer, methacrylic acid Adhesives such as ester-based copolymers, natural rubber-based, and cyanoacrylate-based copolymers, and pressure-sensitive adhesives obtained by adding an appropriate tackifier to these adhesives are included. Further, if necessary, a plasticizer, a filler, an antioxidant, etc. can be added.

Among the above-mentioned adhesives, an elastic adhesive containing a synthetic rubber or a siloxane crosslinked polymer as a main component is particularly preferable because it has a cushioning function and a large ability to relieve stress. As an elastic adhesive containing a siloxane cross-linked polymer as a main component, for example, a liquid polymer containing an amino group capable of reacting with an epoxy group, having a main chain structure of polyoxypropylene, and having a moisture-curable silyl group, A composition containing an epoxy resin as a main component can be given.
In addition, examples of the elastic pressure-sensitive adhesive having a cushion function include an acrylic foam pressure-sensitive adhesive.

The viscosity of the adhesive or pressure-sensitive adhesive is adjusted by adding water or an organic solvent, if necessary, and applied to a support or paper or film by a conventional method. An agent layer is formed. The thickness of the adhesive layer or the pressure-sensitive adhesive layer is preferably about 1 to 40 μm.

In order to improve the printability of the thermal head, a sheet having a cushioning property may be provided between the substrate and the thermoreversible recording label. That is,
An adhesive layer or a pressure-sensitive adhesive layer is also provided between the base material and the sheet having cushioning property to adhere or stick the sheet having cushioning property to the base material, and furthermore, a thermoreversible recording label is formed on the sheet having cushioning property. Paste it. With such a configuration, contact between the thermal head and the thermoreversible recording label is improved, and image uniformity is improved.

[0089]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. In the examples, "parts" represents parts by weight. Example 1 A solution consisting of 7 parts of behenic acid (manufactured by Miyoshi Oil & Fats Co., Ltd., behenic acid 95) 30 parts of vinyl chloride-vinyl acetate copolymer (manufactured by Union Carbide Co., Ltd., VYHH) 180 parts of tetrahydrofuran 20 parts of toluene was placed in a glass bottle. Further, 3 parts of CH ₃ (CH ₂ ) ₁₇ -NHCONH- (CH ₂ ) ₅ -COOH was added, and ceramic beads having a diameter of about 2 mm were further placed in a glass bottle. The bottle was then sealed with a lid. Using a paint shaker (made by Asada Iron Works Co., Ltd.),
The dispersion was performed for about 18 hours to prepare a dispersion having an average particle size of about 6 μm.

This liquid was applied on a transparent polyester film (Lumirror T-60, manufactured by Toray Industries, Inc.) having a thickness of about 50 μm, and dried by heating to form a heat-sensitive layer having a thickness of about 12 μm. A 10 part 75% butyl acetate solution of a urethane acrylate-based ultraviolet-curable resin (Unidick C7-157, manufactured by Dainippon Ink and Chemicals, Inc.) is coated on the wire bar with a solution composed of 10 parts of isopropyl alcohol, and heated and dried. Later, 8
UV light is irradiated with a high-pressure mercury lamp of 0 w / cm and cured.
An overcoat layer having a thickness of about 3 μm was provided to produce a thermoreversible recording medium.

Example 2 A magnetic raw material manufactured by Dainippon Ink and Chemicals, Inc. (Memory Dick DS)
A magnetic reflection layer and a self-cleaning layer coated on a transparent PET film having a thickness of -1811-1040: 188 μm) were vacuum-deposited with about 400 ° Al on the PET film side to provide a light reflection layer. A solution consisting of 10 parts of vinyl chloride-vinyl acetate-phosphate ester copolymer (Denka Vinyl # 1000P, manufactured by Denki Kagaku Kogyo Co., Ltd.) 45 parts of methyl ethyl ketone 45 parts of toluene 45 ° C. A thick adhesive layer was provided. Furthermore, the thickness of the heat-sensitive layer is
A thermosensitive layer and an overcoat layer were provided in the same manner as in Example 1 except that m was used, and a thermoreversible recording medium was produced.

Example 3 8.5 parts of behenic acid and CH ₃ (CH ₂ ) ₁₇ -NHCONH-
Example 1 except that 1.5 parts of (CH ₂ ) ₅ —COOH was used.
In the same manner as in the above, a thermoreversible recording medium was produced. Example 4 5 parts of behenic acid, CH ₃ (CH ₂ ) ₁₇ -NHCONH- (C
Except that the H ₂₎ a ₅ -COOH 5 parts, to prepare a thermoreversible recording medium in the same manner as in Example 1. Example 5 Behenic acid was replaced with 12-tricosanone (manufactured by Tokyo Chemical Industry Co., Ltd., reagent)
A thermoreversible recording medium was prepared in the same manner as in Example 1 except that 5.2 parts and 1.8 parts of 14-heptacosanone (manufactured by Tokyo Chemical Industry Co., Ltd.) were used. Example 6 A thermoreversible recording medium was produced in the same manner as in Example 1 except that behenic acid was changed to stearyl stearate (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.). Example _{7 CH 3 (CH 2) 17} -NHCONH- (CH 2) is a ₅ -COOH except that the _{CH 3 (CH 2) 19 -SO} 2 -CH 2 -COOH, thermally reversible in the same manner as in Example 1 A recording medium was manufactured. Except that in Example _{8 CH 3 (CH 2) 17} -NHCONH- (CH 2) a _{5 -COOH CH 3 (CH 2)} 16 -CONH-CH 2 -COOH, thermally reversible recording in the same manner as in Example 1 A medium was prepared. Except that in Example _{9 CH 3 (CH 2) 17} -NHCONH- (CH 2) a _{5 -COOH CH 3 (CH 2)} 11 -NHCO- (CH 2) 4 -COOH, in the same manner as in Example 1 A thermoreversible recording medium was produced. Example _{10 CH 3 (CH 2) 17} -NHCONH- (CH 2) a _{5 -COOH HOCO- (CH 2) 11} -NHCO- (CH 2) 2 -COOH
A thermoreversible recording medium was produced in the same manner as in Example 1 except for the above.

Example 11 30 parts of a vinyl chloride-vinyl acetate copolymer was converted to vinyl chloride
Example 1 except that 28 parts of a vinyl acetate-hydroxypropyl acrylate copolymer (TA2 manufactured by Nissin Chemical Co.) was used.
A dispersion was prepared in the same manner as described above. To 235 g of this dispersion, a polyisocyanate crosslinking agent (solid content: 75%,
2 g of Coronate HL (manufactured by Nippon Polyurethane Industry Co., Ltd.) was uniformly mixed, and a heat-sensitive layer was provided in the same manner as in Example 1.
The resin and the polyisocyanate were left to stand in a thermostat at 24 ° C. for 24 hours to crosslink. Further, an overcoat layer was provided thereon in the same manner as in Example 1 to produce a thermoreversible recording medium.

Comparative Example 1 Example 1 was repeated except that the coating solution for the heat-sensitive layer was as follows.
In the same manner as in the above, a thermoreversible recording medium was produced. Behenic acid (manufactured by Miyoshi Oil & Fat Co., Ltd., behenic acid 95) 7 parts Eicosane diacid (manufactured by Okamura Oil Co., Ltd., SL-20-90) 3 parts Vinyl chloride-vinyl acetate copolymer 30 parts (manufactured by Union Carbide Company, VYHH) 180 parts of tetrahydrofuran and 20 parts of toluene were uniformly dissolved.

Comparative Example 2 5.2 parts of 12-tricosanone (manufactured by Tokyo Chemical Industry Co., Ltd.) and 14-heptacosanone (manufactured by Tokyo Chemical Industry Co., Ltd.)
(Reagent) A thermoreversible recording medium was prepared in the same manner as in Example 1 except that 1.8 parts were used.

Next, the following measurements were performed. (1) Transparency temperature range and width The thermoreversible recording media according to Examples 1 to 11 and Comparative Examples 1 and 2 were heated using a thermal gradient tester (HG-100, manufactured by Toyo Seiki) for a heating time of 1 second and a pressure of about 1 second. 2.5 kg / cm ² , the temperature was changed at 1 ° C. intervals, heated, and then cooled to room temperature.
In the case of Examples 3 to 11 and Comparative Examples 1 and 2, a film in which Al was deposited at a thickness of about 400 on a transparent PET film on the back surface of the heated portion (Toyo Metallizing Co., Ltd., # 50 Metal Me) was deposited on the back side. In the case of Example 2, the density value after heating to each temperature was measured using a Macbeth RD914 reflection densitometer as it was.

(2) Change in erasability due to repetition of print erasure Table 6 shows the range of the transparent temperature and the range of the transparent temperature. Further, using a reader / writer RC-30 / M20 manufactured by Oki Electric Co., turbid printing was performed with energy slightly lower than the saturated printing energy of each medium, and erased (cleared) with a built-in hot stamp. After printing and erasing were repeated 10 times, the medium was left at 40 ° C. for 24 hours, and the printing and erasing were repeated 100 times in total. Table 6 shows the densities of the initial transparent state and the erased (cleared) state after repeating 100 times.

(3) Repeating durability Using the media of Examples 1 and 11, a reader / writer R made by Oki Electric
Using C-30 / M20, white turbid printing was performed at an energy about 40% higher than the saturated printing energy of each medium, and erasing (clearing) was repeated 50 times with a built-in hot stamp. Shows that the turbidity was significantly reduced to 0.52 after the repetition with respect to the initial concentration of 0.12. Decrease was small.
The increase in printing energy of about 40% is a compulsory test of about 10 times when the number of repetitions is increased.

[0099]

[Table 6]

[0100]

As is apparent from the detailed and concrete description, according to the present invention, the temperature range for making transparent is widened,
Provided are a thermoreversible recording medium and a card which can obtain sufficient transparency and thus sufficient contrast even when the environmental temperature changes, and whose erasability is not reduced even by repetition of printing and erasing. An extremely excellent effect is provided in that an image processing method and apparatus suitable for using a thermoreversible recording medium are provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change in transparency by a thermoreversible recording medium according to the present invention.

FIG. 2 is a diagram showing a layer configuration example of a thermoreversible recording medium according to the present invention.

FIG. 3 is a diagram illustrating an example of a thermoreversible recording medium according to the present invention.

FIG. 4 is a diagram illustrating another example of the thermoreversible recording medium according to the present invention.

FIG. 5 is a diagram illustrating an example of use of a thermoreversible recording medium according to the present invention.

FIG. 6 is a diagram illustrating an example of a thermoreversible recording apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermoreversible recording medium 11 Support 12 Aluminum reflective layer 13 Sensitive recording layer 14 Protective layer 15 Transparent PET film 16 Air layer 17 Adhesive layer 20 Magnetic coating layer 21 Card 22 Rewriting recording part 23 Depression part for IC chip 24 Label processing of rewriting recording section 30 Doorway 31 Conveyance roller 32 Guide roller 33 Sensor 34 Magnetic head 34c Control means 35 Platen roller 36 Guide roller 37 Transport roller 38 Ceramic heater 38c Control means 39 Guide roller 40 Transport roller 43 Sensor 44 Platen roller 45 Transport Roller 46 transport roller 47 transport roller 48 transport belt 49a transport path 49b transport path 50 transport path 51 sensor 52 platen roller 53 thermal head 53c control means 54 transport path 55a transport path switching means 55b transport path switching means 56a transport path 56b transport path 57a limit switch 57b limit switch 58 transport belt 59 transport roller 60 guide roller 61 outlet 231 wafer 232 wafer substrate 233 integrated circuit 234 contact terminal 235 CPU 236 ROM 237 RAM 238 input / output interface 239 Information on RAM storage area

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shigeyuki Harada 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Masafumi Torii 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Kunitoshi Sugiyama 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Hideyuki Kobori 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Katsuyuki Sugiyama 4-66-1, Horikiri, Katsushika-ku, Tokyo Miyoshi Oil & Fat Co., Ltd. (72) Inventor Katsuaki 4-66-1, Horikiri, Katsushika-ku, Tokyo Miyoshi Oil & Fat Co., Ltd. (72) Invention Person Koji Kawai 4-66-1, Horikiri, Katsushika-ku, Tokyo Inside Miyoshi Yushi Co., Ltd. (72) Inventor Kazuo Hosoda 4-66-1, Horikiri, Katsushika-ku, Tokyo Mi The shea oils and fats Co., Ltd. (72) inventor Masafumi Moriya Katsushika-ku, Tokyo Horikiri 4-chome No. 66 No. 1 Miyoshi Oil & Fat Co., Ltd. in

Claims (16)

[Claims] 1. A thermoreversible layer comprising, on a support, a heat-sensitive layer having a resin base material and an organic low-molecular-weight substance dispersed in the resin base material as main components, and having a transparency reversibly changing depending on temperature. In the recording medium, as the organic low-molecular substance, at least one of a linear hydrocarbon-containing compound (A) having at least one of a urea bond, a sulfonyl bond, and an amide bond and having a carboxyl group and having a melting point of less than 130 ° C; A thermoreversible recording medium comprising a mixture of at least one kind of the linear hydrocarbon-containing compound (B) having a melting point lower than the melting point of the hydrogen-containing compound (A) by 20 ° C. or more. 2. The thermoreversible recording medium according to claim 1, wherein the melting point of the linear hydrocarbon-containing compound (A) is 100 ° C. or higher. 3. The thermoreversible recording medium according to claim 1, wherein the linear hydrocarbon-containing compound (B) has a melting point of 50 ° C. or more and less than 100 ° C. 4. The mixture ratio of the linear hydrocarbon-containing compound (A) and the linear hydrocarbon-containing compound (B) is 90:10 to 2: 9.
8. The method according to claim 1, wherein the number is eight.
3. The thermoreversible recording medium according to claim 1. 5. The compound (A) containing a linear hydrocarbon,
5. The thermoreversible recording medium according to claim 1, wherein a linear hydrocarbon-containing compound having a urea bond and a carboxyl group is used. 6. As the linear hydrocarbon-containing compound (A),
The thermoreversible recording medium according to any one of claims 1 to 4, wherein a linear hydrocarbon-containing compound having a sulfonyl bond and a carboxyl group is used. 7. The straight-chain hydrocarbon-containing compound (A)
5. The thermoreversible recording medium according to claim 1, wherein a linear hydrocarbon-containing compound having an amide bond and a carboxyl group is used. 8. The linear hydrocarbon-containing compound (B) is an aliphatic monocarboxylic acid, a fatty acid ester, a ketone having a higher alkyl group, a dibasic acid ester, a polyhydric alcohol difatty acid ester, an aliphatic amide compound, or a fatty acid. The thermoreversible recording medium according to any one of claims 1 to 7, wherein the thermoreversible recording medium is at least one selected from group urea compounds. 9. The thermoreversible recording medium according to claim 1, wherein a resin base material is crosslinked. 10. A thermoreversible recording medium comprising the heat-sensitive layer according to claim 1 and an information recording section, and having a card shape. 11. The thermoreversible recording medium according to claim 11, wherein the information recording section is at least one selected from a magnetic recording layer, an IC, and an optical memory. 12. A thermoreversible layer comprising, as a main component, a resin base material and a low-molecular organic substance dispersed in the resin base material, and a heat-sensitive layer whose transparency reversibly changes depending on temperature. In the method for producing a recording medium, a dispersion in which one or more organic low-molecular substances are dispersed in a resin solution in a solid state is coated on a support, and heated and dried. The method for producing a thermoreversible recording medium according to any one of claims 1 to 11, wherein the thermosensitive layer is formed by dissolving in a dispersion solvent. 13. An image processing apparatus for a thermoreversible recording medium using the thermoreversible recording medium according to claim 1 for recording and erasing an image by heating. 14. The image processing apparatus according to claim 13, wherein the image is erased by a ceramic heater. 15. The thermoreversible material according to claim 1, wherein an adhesive layer or a pressure-sensitive adhesive layer is provided on a surface of the support opposite to the surface on which the heat-sensitive layer is formed, and the support has a label shape. recoding media. 16. A method in which the heat-sensitive layer according to any one of claims 1 to 9 is formed on a disk or a package of the disk, or the label-like thermoreversible recording medium according to claim 15 is adhered. Features disc with reversible display and disc package with reversible display.