JP2001063226A - Reversible heat-sensitive recording body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reversible heat-sensitive recording body wherein a coloring image is formed on a white ground by using a small-size apparatus, color- developing and decoloring can be executed only by a difference of heating conditions, a high contrast is provided, and retention properties of the image is excellent. SOLUTION: A sheet-like substrate, a heat-sensitive recording layer which is formed on the sheet-like substrate and contains a colorless or light-colored dye-precursor and a developer for reversibly coloring and decoloring the same, and further as the developer, a compound containing at least one ethynyl group in one molecule and at least one >=11C long chain hydrocarbon group contained is provided in a reversible heat-sensitive recording body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible thermosensitive recording medium capable of performing color development and decoloring by controlling heating conditions and maintaining the color developing state and the color decoloring state at room temperature. To elaborate further,
The present invention relates to a reversible thermosensitive recording medium that forms a color image on a white background, has high contrast, and has excellent image storability.

[0002]

2. Description of the Related Art Conventionally, heat-sensitive recording media have a compact recording device, are inexpensive, and are easy to maintain. Therefore, computers, measuring instruments, registers, CD / ATMs, facsimile machines, automatic ticket vending machines, handy terminals, etc. However, recently, it has been used as a magnetic heat-sensitive card such as a prepaid card or a point card due to its combination with magnetic recording. In these magnetic cards, the magnetic information is rewritten each time it is used, but the thermal recording image is not rewritten. Therefore, new information such as the residual number is added to the portion where no image is recorded. However, since the area of the recordable portion is limited, the actual situation is that the amount of information to be thermally recorded is unavoidably reduced, or the card is recreated when the recording area is exhausted. As means for solving such a problem, development of a reversible thermosensitive recording medium which can be rewritten any number of times is strongly desired.

[0003] Against the background of garbage problems and deforestation problems that have been actively discussed in recent years, there is a demand for the recycling of thermal recording paper. There are various methods for regenerating thermosensitive recording paper. Among them, as a versatile method that does not require a large device such as a deinking device, the development of a reversible thermosensitive recording material that can be rewritten many times has been developed. Is desired. Further, the reversible thermosensitive recording medium has attracted attention as a recording material for a simple display as disclosed in JP-A-3-233490 and JP-A-5-42762, and is suitable for these apparatuses. The development of a reversible thermosensitive recording medium is also strongly desired.

[0004] Against this background, various reversible thermosensitive recording media have been proposed. For example, JP-A-63-107
JP-A-584, JP-A-4-78573 and JP-A-4-35878 disclose a polymer type reversible thermosensitive recording medium utilizing a change in transparency due to heating conditions. However, this method has a disadvantage that visibility in a dark place is poor. Further, there is also a drawback that a white image is recorded on a colored background, and it is difficult to obtain a so-called paper-like recording body that records a colored image on a white background.

As a method for solving these problems, there has been proposed a dye-type reversible thermosensitive recording medium which enables reversible recording while using a dye used in a conventional thermosensitive recording medium. The dye-type reversible thermosensitive recording medium is easy to record a color image on a white background, and is a recording method using a change in absorption wavelength due to heating conditions.
A relatively high contrast is obtained. For example, the following system is known as a dye type reversible thermosensitive recording medium. JP-A-63-173684 discloses a method using an ascorbic acid derivative as a color developer. However, there is a disadvantage that the color is not sufficiently erased during erasing.

[0006] JP-A-5-124360 and JP-A-6-210954 disclose a method in which an organic phosphoric acid compound having a long-chain alkyl group or a phenolic compound is used as a developer. However, at the time of erasing, there are drawbacks in that the color may not be sufficiently erased and the storage stability of the color image may be insufficient. As described above, a number of techniques have been disclosed for reversible thermosensitive recording media, but each of them has various drawbacks, and none of them has sufficiently satisfactory performance for practical use.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a color image can be formed on a white background using a small apparatus, and color development and decoloration can be performed only by a difference in heating conditions. An object of the present invention is to provide a reversible thermosensitive recording medium having excellent image storability.

[0008]

The inventors of the present invention can perform color development and color erasing only by heating, and have a high reversible thermal color development and a color erasable reversible color with a high contrast between the color development area and the color erasure area. Focusing on a dye-type reversible thermosensitive recording system that uses the reaction between a dye and a developer to obtain a thermal recording material, and as a result of intensive research, used a terminal alkyne compound having a long-chain hydrocarbon group as a developer. As a result, it has been found that a desired reversible thermosensitive recording medium can be obtained, and the present invention has been completed.

The reversible thermosensitive recording material of the present invention comprises a sheet-like support, a colorless or light-colored dye precursor formed on the sheet-like support, and a developer for reversibly coloring and decoloring the dye precursor. A thermosensitive recording layer containing a colorant, and further comprising, as the color developer, a compound having an ethynyl group and a long-chain hydrocarbon group having 11 or more carbon atoms in one molecule.

Among the developers of the present invention, the following [formula 5]
Alternatively, those represented by the general formula of [Formula 6] are preferable.

Embedded image (However, m represents an integer of 0 to 3. R ¹ represents a single bond or any of a hydrocarbon group, an aromatic ring, and a heteroaromatic ring having a total of 1 to 30 carbon atoms. R ² represents a single bond. Or a hydrocarbon group having a total of 1 to 30 carbon atoms,
R ³ represents a hydrocarbon group having a total of 1 to 30 carbon atoms. However, either R ² or R ³ is a long-chain hydrocarbon having 11 or more carbon atoms. )

[0011]

Embedded image (However, R ⁴ and R ⁷ each independently represent a single bond or any of a hydrocarbon group, an aromatic ring, and a heteroaromatic ring having a total of 1 to 30 carbon atoms. R ⁵ and R ⁶ each independently represent a single bond. A bond or a hydrocarbon group having a total of 1 to 30 carbon atoms is represented, provided that any one of R ⁴ , R ⁵ , R ⁶ and R ⁷ is a long-chain hydrocarbon having 11 or more carbon atoms.)

In the above formulas [5] and [6],
X, Y and Z are each independently a single bond or the following chemical formula:

Embedded image Represents one member selected from the divalent group represented by

The reversible thermochromic recording and decoloring method of the reversible thermosensitive recording medium according to the present invention is characterized in that the thermosensitive coloring layer of the recording medium is heated to color-record an image, and after the recording has been used,
The heat-sensitive coloring layer is heated at a temperature lower than the coloring heating temperature to erase the color-developed image.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the reversible thermosensitive recording medium of the present invention, a thermosensitive recording layer containing a dye precursor and a color developer develops color rapidly by heating, and the color development state is maintained at room temperature by rapid cooling. Is done. On the other hand, the color image portion held at room temperature can be erased by heating to a color development temperature or lower, and the decolored state is maintained even when cooled to room temperature. Although the action mechanism of this color development / decoloration is not clear, the hydrogen atom of the ethynyl group in the terminal alkyne compound used as a color developer shows a strong color development ability with respect to a basic leuco dye, and color development occurs. On the other hand, when the color former is heated below the color development temperature, the long-chain hydrocarbon groups in the color developer are oriented to induce crystallization of the color developer, and the dye and the color developer are separated and decolorized. It is considered something. Generally, the heating temperature for color development is 80 to 180 ° C., the temperature range in which decoloration occurs is 50 to 120 ° C., and lower than the color heating temperature. Generally, color development is easy for rapid cooling after heating,
Decoloring is performed by using a thermal head or the like. Decoloring is performed by maintaining the temperature in a temperature range equal to or lower than the color heating temperature, and there is no need to control the heating / cooling speed. The temperature holding time at the time of decoloring is preferably 0.1 second or more.

Specific examples of the terminal alkyne-based compound used as a color developer in the reversible thermosensitive recording medium of the present invention are shown in the following [Chemical formula 8] and [Chemical formula 9], but are not limited thereto. These compounds may be used alone or as a mixture of two or more.

[0016]

Embedded image

[0017]

Embedded image

Further, the length of the long-chain hydrocarbon group of the color developer according to the present invention needs to have 11 or more carbon atoms, and preferably 30 or less. Even in that region, it is more preferable that the number is 14 to 21. If the number of carbon atoms is less than 11, the decoloring ability does not reach a practical level, and 3
If it exceeds 0, the color developing ability may decrease. In the thermosensitive recording layer of the reversible thermosensitive recording medium of the present invention, the compound used as a dye precursor includes triphenylmethane-based, fluoran-based, and diphenylmethane-based compounds, and can be selected from conventionally known compounds. . For example,
3- (4-diethylamino-2-ethoxyphenyl)-
3- (1-ethyl-2-methylindol-3-yl)
-4-azaphthalide, crystal violet lactone, 3- (N-ethyl-N-isopentylamino) -6
-Methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7- (o, p-dimethylanilino) fluoran, 3- (N -Ethyl-N-p-toluidino) -6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofur Oran,
3- (N-cyclohexyl-N-methylamino) -6
Methyl-7-anilinofluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-diethylamino-7- (m-trifluoromethylanilino) fluoran, 3-diethylamino-6-methyl-7-chloro Fluoran, 3-diethylamino-6-methylfluoran, and 3-cyclohexylamino-6-chlorofluoran.

Further, 3- (N-ethyl-N-cyclohexyl) -6-methyl-7- (p-chloroanilino)
Fluoran, 3-di (n-pentyl) amino-6-methyl-7-anilinofluoran, 3- [N- (3-ethoxypropyl) -N-ethylamino] -6-methyl-7-
Anilinofluoran, 3- (Nn-hexyl-N-ethylamino) -7- (o-chloroanilino) fluoran, 3- (N-ethyl-N-2-tetrahydrofurfurylamino) -6-methyl- 7-anilinofluoran, 3
-(N-ethyl-N-isopentylamino) -6-methyl-7-anilinofluoran, 2,2-bis {4-
[6 ′-(N-cyclohexyl-N-methylamino)-
3′-Methylspiro [phthalide-3,9′-xanthen] -2′-ylamino] phenyl} propane and 3
One or more selected from -dibutylamino-7- (o-chloroanilino) fluoran and the like can be used.

In the present invention, it can be used in combination with a conventionally known developer consisting of phenols or organic acids and sulfonyl (thio) ureas as long as the desired effect is not impaired.

These conventional developers are, for example, 2,2-
Bis (4-hydroxyphenyl) propane (bisphenol A), 1,1-bis (4-hydroxyphenyl)-
1-phenylethane, 1,4-bis (1-methyl-1-
(4′-hydroxyphenyl) ethyl) benzene, 1,
3-bis (1-methyl-1- (4′-hydroxyphenyl) ethyl) benzene, dihydroxydiphenyl ether (JP-A-1-180382), benzyl p-hydroxybenzoate (JP-A-5140483), Bisphenol S, 4-hydroxy-4'-isopropyloxydiphenyl sulfone (JP-A-60-13)
852), 1,1-di (4-hydroxyphenyl) cyclohexane, 1,7-di (4-hydroxyphenylthio) -3,5-dioxaheptane (Japanese Unexamined Patent Publication No.
52694), 3,3'-diallyl-4,4'-
Dihydroxydiphenyl sulfone (JP-A-60-208)
286).

Further, N- (p-toluenesulfonyl) -N'-phenylurea, N- (p-toluenesulfonyl) -N '-(p-methoxyphenyl) urea,
-(P-toluenesulfonyl) -N '-(o-tolyl)
Urea, N- (p-toluenesulfonyl) -N '-(m
-Tolyl) urea, N- (p-toluenesulfonyl)-
N '-(p-tolyl) urea, N- (p-toluenesulfonyl) -N'-benzylurea
No. 2061), 4,4′-bis (p-toluenesulfonylaminocarbonylamino) -diphenylmethane,
4,4'-bis (o-toluenesulfonylaminocarbonylamino) -diphenylmethane, 4,4'-bis (benzenesulfonylaminocarbonylamino) -diphenylmethane, 1,2-bis [4 '-(p-toluenesulfonylaminocarbonyl) Amino) phenyloxy] ethane, 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenyl ether and 3,3'-
Bis (p-toluenesulfonylaminocarbonylamino) diphenylsulfone (as described in JP-A-5-14735)
No. 7).

The reversible thermosensitive recording medium of the present invention can contain a thermofusible substance generally known as a sensitizer in the thermosensitive recording layer. These include, for example, oxalic acid diesters (JP-A 64-1583), di (4-methylbenzyl) oxalate (JP-B 5-62597), 1,
2-bis (m-tolyloxy) ethane (JP-A-60-5)
6588), diphenyl sulfone (JP-A-60-1985)
15667), p-benzylbiphenyl (JP-A-60-82382), [1,4-bis {2- (4
-Methylbenzyloxy) ethoxy}] benzene (JP-A-11-20320), phenyl 1-hydroxy-2-naphthoate (JP-A-57-19089), dibenzyl terephthalate (JP-A-58-98)
285), benzyl p-benzyloxybenzoate (JP-A-57-201691), diphenyl carbonate, ditolyl carbonate (JP-A-58-136489), and m-terphenyl (JP-A-57-89994). Publication), 1,5-bis (p-methoxyphenoxy) -3-
Oxapentane (JP-A-62-181183),
1,4-bis (p-tolyloxy) benzene (Japanese Unexamined Patent Application Publication No.
-153783), benzenesulfanilide (JP-A-58-21493), 2-chloroacetoacetanilide, 4-ethoxymethylsulfonylbenzene, 4-methoxyacetoacetanilide, o-methylacetoanilide, 4-methoxybenzenesulfanilide ,
These compounds include 3,4-dimethylacetanilide and 2-methoxybenzenesulfoanilide, and these compounds accelerate the decoloration reaction in addition to the ability to form a high-density color on a reversible thermosensitive recording medium with a relatively low applied energy. It also has the ability to improve reversibility.

The heat-sensitive recording layer of the present invention may further contain waxes and pigments as long as the effects of the present invention are not impaired, and usually contains a binder. Known waxes such as paraffin, amide wax, bisimide wax, and metal salts of higher fatty acids can be used.

Examples of the pigment include inorganic fine particles such as silica, clay, calcined clay, talc, calcium carbonate, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate and surface-treated calcium carbonate and silica. In addition to powder, organic fine powder such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin can be used. As the binder, polyvinyl alcohol of various molecular weights,
Starch and derivatives thereof, methoxycellulose, carboxymethylcellulose, methylcellulose, cellulose derivatives such as ethylcellulose, sodium polyacrylate,
Polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, and Water-soluble polymer materials such as casein, and polyvinyl acetate, polyurethane,
Latexes such as styrene / butadiene copolymer, polyacrylic acid, polyacrylate, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer, and styrene / butadiene / acrylic copolymer Can be used.

In the heat-sensitive recording layer of the reversible heat-sensitive recording material of the present invention, the content of the dye precursor is generally preferably 5 to 40% by weight of the dry weight of the heat-sensitive recording layer, and the content of the developer Is preferably 5 to 50% by weight of the dry weight of the heat-sensitive recording layer. 5% by weight of developer
If the amount is less than 50%, the color developing ability becomes insufficient. Even if it is used in a large amount exceeding 50% by weight, the color developing ability is saturated, and there is no particular improvement in the contrast between the coloring density and the decoloring density. May be economically disadvantageous.

Further, when the heat-sensitive recording layer contains a conventionally known color developer composed of phenols, organic acids, or sulfonyl (thio) ureas, the content is 10% by weight or less of the weight of the heat-sensitive recording layer. It is preferred that When the content of the conventionally known color developer composed of phenols, organic acids, or sulfonyl (thio) ureas is more than 10% by weight, the decoloring reaction is inhibited, and the contrast between the color-developed portion and the decolored portion is reduced. May occur.

When the wax and the pigment are contained in the heat-sensitive recording layer, the content thereof is 5 to 20% by weight, respectively.
It is preferably from 0 to 50% by weight, and the content of the binder is generally from 5 to 20% by weight.

The support used in the reversible thermosensitive recording medium of the present invention.
The carrier is paper (acidic) that has been used for conventional thermal recording media.
Paper, neutral paper), and apply pigment, latex, etc.
Coated paper, laminated paper, polyolefin-based
Synthetic paper, polyolefin, polyester made from resin
Glass in addition to plastic films such as
You can choose from plates, conductive rubber sheets, etc.
You. On at least one surface of such a support, the required
Apply a coating solution containing a mixture of components and dry to
A thermal recording medium is manufactured. The amount of coating is the same as when the coating liquid layer was dried.
1 to 15 g / m in the state ^TwoIs preferably 2 to 10 g / m^TwoBut special
Preferred.

In the present invention, an undercoat layer may be provided below the reversible thermosensitive coloring layer. Further, a back layer can be provided on the back surface of the reversible thermosensitive recording medium to prevent blocking at the time of contact between the surfaces, suppress permeation of water or oil from the back surface, and control curl. Furthermore, in order to improve the heat resistance, light resistance, printability, and the durability of repeated coloring and decoloring, a protective layer, a coating layer such as a printing layer may be formed on the reversible thermosensitive coloring layer. it can. The light resistance can be improved by including an ultraviolet absorber in the protective layer. In addition, by using a surface resin-applied cured layer containing, as a main component, an unsaturated organic compound curable by irradiation with an electron beam as the protective layer, it is possible to drastically improve the durability of repeated coloring and decoloring.

In the present invention, the reversible thermosensitive recording medium can be further processed in order to increase the added value of the reversible thermosensitive recording medium to give a higher function. For example, adhesive paper, re-wet adhesive paper, delayed-tack paper by applying processing with adhesive, re-wet adhesive, delayed-tack adhesive on the back surface, or reversible heat-sensitive that can be magnetically recorded by magnetic processing It can be a recording medium. In addition, a recording paper capable of recording on both sides can be provided by using the back surface to have a function as thermal transfer paper, inkjet paper, carbonless paper, electrostatic recording paper, and xerographic paper. Of course, a double-sided reversible thermosensitive recording medium can also be used. The device for recording (coloring) and erasing (erasing) images can be selected from thermal heads, thermostats, heating rollers, hot pens, sheet heating elements, laser light, infrared light, etc., depending on the purpose of use. It is not particularly limited to these.

<Synthesis Example> A synthesis example of the reversible thermosensitive developer in the present invention is shown below, and the present invention will be specifically described.
All syntheses were performed under an argon stream, and the solvent used was anhydrous.

<Synthesis Example 1> Compound N was prepared by the following procedure.
o. 1 (however, a = 16) was synthesized. 12 g of 4-ethynylaniline, 300 mL of tetrahydrofuran, and 15 mL of pyridine were placed in a 1-L eggplant-shaped flask and stirred at room temperature, and 30 g of stearic acid chloride was added to 300 mL of tetrahydrofuran.
Was slowly added dropwise using a dropping funnel.
Colorless crystals precipitate immediately. After stirring at room temperature for 18 hours, the reaction solution was poured into a 1-L beaker containing 0.5N-hydrochloric acid (300 mL) and stirred for 10 minutes. The precipitated crystals were collected by filtration, washed with distilled water, and dried under vacuum. The obtained crude crystals were purified by recrystallization from ethanol to give the desired product as a colorless powder. (Yield 35 g, yield 90%)

The analytical values of the crystals were as follows. Results of IR measurement (KBr tablet method) : 3320,328
9,2915,2848,2130,1667,158
5,1524,833 cm ^-1

Mass spectrum result : 383 (M ⁺ )

Result of melting point measurement : 115 ° C.

<Synthesis Example 2> Compound N was prepared by the following procedure.
o. 2 (however, a = 17) was synthesized. 30 g of octadecyl isocyanate, 12 g of 4-ethynylaniline and 600 mL of 2-butanone were placed in a 1-L eggplant-shaped flask, and refluxed for 1 hour.
After stirring for 2 hours, the mixture was allowed to stand at room temperature. The precipitated crystals were collected by filtration, washed with ice-cooled 2-butanone, and dried under vacuum. The obtained crude crystals were purified by recrystallization from ethanol to give the desired product as a colorless powder. (35 g, 85% yield)

The analytical values of the crystals were as follows. Results of IR measurement (KBr tablet method) : 3330,328
9,2920,2847,2130,1628,158
2,1557,1468,837cm ^-1

Mass spectrum result : 412 (M ⁺ )

Result of melting point measurement : 123 ° C.

<Synthesis Example 3> Compound N was prepared by the following procedure.
o. 4 (however, a = 5, b = 16) was synthesized. 13 g of ε-aminocaproic acid, 150 mL of tetrahydrofuran, 15 mL of pyridine were placed in a 500 mL eggplant-shaped flask and stirred at room temperature,
Add 30 g of stearic acid chloride to tetrahydrofuran
The solution dissolved in 150 mL was slowly dropped using a dropping funnel. Colorless crystals precipitate immediately. After stirring at room temperature for 18 hours, the reaction solution was poured into a 1-L beaker containing 0.5N-hydrochloric acid (300 mL) and stirred for 10 minutes. The precipitated crystals were collected by filtration, washed with distilled water, and dried under vacuum. The obtained crude crystals were purified by recrystallization from toluene to obtain 36 g of a carboxylic acid as an intermediate as a colorless powder. The whole amount of the intermediate and 700 mL of tetrahydrofuran were put in a 1-L eggplant-shaped flask and suspended at 60 ° C., and 12 g of 1-hydroxybenzotriazole, 12 g of diisopropylcarbodiimide, and 11 g of 4-ethynylaniline were added in that order, and reflux cooling was performed. The tube was attached and heated to reflux for 3 hours. Thereafter, the reaction solution was allowed to stand at room temperature, and the precipitated crystals were collected by filtration, washed with distilled water, and dried in vacuo. The obtained crude crystals were purified by recrystallization from ethanol to give the desired product as a colorless powder. (Yield 39 g, yield 75
%)

The analytical values of the crystals were as follows. Results of IR measurement (KBr tablet method) : 3328, 291
9,2850,1810,1633,1531,107
4cm ^-1

Mass spectrum result : 496 (M ⁺ )

Result of melting point measurement : 130 ° C.

<Synthesis Example 4> Compound N was prepared by the following procedure.
o. 6 (however, a = 17) was synthesized. 30 g of octadecyl isocyanate, 15 g of 4-aminobenzoic acid and 650 mL of 2-butanone were placed in a 1-L eggplant-shaped flask, and refluxed for 12 hours.
After stirring for an hour, the mixture was allowed to stand at room temperature. The precipitated crystals were collected by filtration, washed with distilled water, and dried under vacuum. The obtained crude crystals were purified by recrystallization from toluene,
38 g of a carboxylic acid as an intermediate was obtained as a colorless powder. The whole amount of the intermediate and 700 mL of tetrahydrofuran were put in a 1-L eggplant-shaped flask and suspended at 60 ° C., and 12 g of 1-hydroxybenzotriazole, 12 g of diisopropylcarbodiimide, and 11 g of 4-ethynylaniline were added in that order, and reflux cooling was performed. The tube was attached and heated to reflux for 3 hours. Thereafter, the reaction solution was allowed to stand at room temperature, and the precipitated crystals were collected by filtration.
After washing with distilled water, vacuum drying was performed. The obtained crude crystals were purified by recrystallization from ethanol to give the desired product as a colorless powder. (37 g, 70% yield)

The analytical values of the crystals were as follows. Results of IR measurement (KBr tablet method) : 3340,292
0,2850,1577,1618,1250,742
cm ^-1

Result of mass spectrum : 531 (M ⁺ )

Result of melting point measurement : 135 ° C.

[0049]

The present invention will be specifically described below with reference to examples. Unless otherwise specified, “parts” and “%” represent “parts by weight” and “% by weight”, respectively.

<Example 1> A reversible thermosensitive recording medium was prepared by the following operation. (1) Preparation of Dispersion Liquid Ingredients Amount of A (parts) 3-dibutylamino-6-methyl-7-anilinofluoran 20 polyvinyl alcohol - using a sand grinder Le 10% solution 10 Water 70 The composition, average Particle size is 1
It was pulverized until it became not more than μm.

[0051] (2) Preparation Ingredients Amount of Dispersion B (Part) Compound No. 1 (however, a = 16) 20 polyvinyl alcohol 10% liquid 10 water 70 The above composition was averaged in particle size of 1 using a sand grinder.
It was pulverized until it became not more than μm.

(3) Formation of reversible thermosensitive recording layer 60 parts of the above-mentioned liquid A, 240 parts of liquid B, 30 parts of calcined clay,
2 parts of a 5% paraffin wax emulsion and 10
% Polyvinyl alcohol aqueous solution (100 parts) was mixed and stirred to obtain a coating solution. This coating solution was applied to a 75 μm-thick polyester film so that the coating amount after drying was 5.0 g / m ^2, and dried to form a reversible thermosensitive recording layer.

(4) Formation of Intermediate Layer 5 parts of a kaolinite clay dispersion (solid content: 60%)
Carboxylic acid-modified polyvinyl alcohol aqueous solution (solid content 1
(0%), 200 parts were mixed and stirred to prepare a coating solution for an intermediate layer. This coating solution was applied onto the heat-sensitive recording layer described in the above item (3) so that the coating amount after drying was 1.5 g / m ^2, and dried to form an intermediate layer.

(5) Formation of Overcoat Layer 40 parts of polyester acrylate (Aronics M-830 manufactured by Toa Gosei Co., Ltd.), 40 parts of polyester acrylate (Aronix M-6200 manufactured by Toa Gosei Co., Ltd.)
20 parts of calcium carbonate (Ryton A, manufactured by Bihoku Powder Chemical Industry Co., Ltd.) was mixed and stirred, and the mixture was applied onto the intermediate layer described in the above item (4) so that the coating amount was 2.5 g / m 2. The obtained coating layer was irradiated with an electron beam under the conditions of an oxygen concentration of 300 ppm or less in an electron beam irradiation chamber, an acceleration voltage of 175 kV, and an absorbed dose of 3 Mrad to form an overcoat layer and obtain a reversible thermosensitive recording medium. .

(6) Color development and color erasure test The reversible thermosensitive recording medium thus obtained was subjected to printing at a printing voltage of 21.degree.
Printing was performed under the conditions of 7 v and a printing pulse of 1.0 ms. The print color density was measured with a Macbeth reflection densitometer RD-914. Furthermore, after heating this color-developed sample under the conditions of a heating temperature of 100 ° C., a pressure of 1 kg / cm ² , and a heating time of 1 second using a thermal gradient tester manufactured by Toyo Seiki, the decolorization density was measured using a Macbeth reflection densitometer RD-914. Was measured. Table 1 shows the test results.

(7) Preservability test After the print color density was measured in the same manner as in the color test of the above item (6), the obtained color sample was allowed to stand at 50 ° C. for one day, and the color density was similarly measured. Was measured. The image storability at this time was evaluated by the following equation: image storability = (color density after standing at 50 ° C. for 1 day / color density immediately after printing) × 100 (%). Table 1 shows the test results.

(8) Repeating Test The color developing density and the color erasing density after repeating the color developing property and the color erasing property test described in the above item (6) 50 times were measured by Macbeth reflection densitometer RD-914. Table 1 shows the test results.

<Example 2> A reversible thermosensitive recording medium was prepared and tested in the same manner as in Example 1. However, when preparing the dispersion B, the compound No. Compound No. 1 in place of a (where a = 16) 1 (where a = 10) was used. Table 1 shows the test results.

Example 3 A reversible thermosensitive recording medium was prepared and tested in the same manner as in Example 1. However, when preparing the dispersion B, the compound No. Compound No. 1 in place of a (where a = 16) 1 (where a = 21) was used. Table 1 shows the test results.

Example 4 A reversible thermosensitive recording medium was prepared and tested in the same manner as in Example 1. However, when preparing the dispersion B, the compound No. Compound No. 1 in place of a (where a = 16) 2 (however, a = 16) was used. Table 1 shows the test results.

Example 5 A reversible thermosensitive recording medium was prepared and tested in the same manner as in Example 1. However, when preparing the dispersion B, the compound No. Compound No. 1 in place of a (where a = 16) 4 (however, a = 5, b = 17) was used.
Table 1 shows the test results.

Example 6 A reversible thermosensitive recording medium was prepared and tested in the same manner as in Example 1. However, when preparing dispersion A, compound No. Compound No. 1 in place of a (where a = 16) 6 (where a = 17) was used. Table 1 shows the test results.

Comparative Example 1 A reversible thermosensitive recording medium was prepared and tested in the same manner as in Example 1. However, when preparing the dispersion B, the compound No. The following compound was used in place of 1 (where a = 16).

Embedded image Table 1 shows the test results.

<Comparative Example 2> A reversible thermosensitive recording medium was prepared and tested in the same manner as in Example 1. However, when preparing the dispersion B, the compound No. The following compound was used in place of 1 (where a = 16).

Embedded image Table 1 shows the test results.

<Comparative Example 3> A reversible thermosensitive recording medium was prepared and tested in the same manner as in Example 1. However, when preparing the dispersion B, the compound No. P-Ethynylundecananilide (total number of carbon atoms is 10) instead of 1 (where a = 16)
Having a long-chain hydrocarbon group). Table 1 shows the test results.

Comparative Example 4 A reversible thermosensitive recording medium was prepared and tested in the same manner as in Example 1. However, when preparing the dispersion B, the compound No. The following compounds were used in place of 1 (where a = 16).

Embedded image Table 1 shows the test results.

Comparative Example 5 A reversible thermosensitive recording medium was prepared and tested in the same manner as in Example 1. However, when preparing the dispersion B, the compound No. The following compounds were used in place of 1 (where a = 16).

Embedded image Table 1 shows the test results.

[0068]

[Table 1]

As is clear from the comparison between Examples 1 to 6 and Comparative Examples 4 and 5, the reversible thermosensitive recording material of the present invention is a color developer such as a phenol compound having a long hydrocarbon chain or phosphoric acid. Has a higher contrast than the compound using, and has excellent storage stability. As is clear from comparison of Examples 1 to 6 and Comparative Examples 1 to 3, the reversible thermosensitive recording medium of the present invention has a terminal alkyne having a long-chain hydrocarbon group having a total of 11 or more carbon atoms. It can be seen that the coloring and decoloring effects are exhibited only when the system compound is used as a color developer.

[0070]

The reversible thermosensitive recording medium of the present invention forms a color image on a white background, has high contrast, and is excellent in image storability. Therefore, the reversible thermosensitive recording medium of the present invention has extremely high practical value.

Claims (3)

[Claims] 1. A sheet-like support, a colorless or light-colored dye precursor formed on the sheet-like support, and a heat-sensitive recording layer containing a color developer for reversibly coloring and decoloring the precursor. And a compound having at least one ethynyl group and at least one long-chain hydrocarbon group having 11 or more carbon atoms in one molecule as the developer. Record body. 2. The developer according to claim 1, wherein the developer has the following general formula: (Where m represents an integer of 0 to 3. X and Y are each independently a single bond or the following chemical formula: Represents one member selected from the divalent group represented by R ¹
Represents a single bond or a hydrocarbon group having 1 to 30 carbon atoms in total, an aromatic ring, or a heteroaromatic ring. R ² represents a single bond or a hydrocarbon group having a total of 1 to 30 carbon atoms, and R ³ represents a hydrocarbon group having a total of 1 to 30 carbon atoms. However, either R ² or R ³ is a long-chain hydrocarbon having 11 or more carbon atoms. The reversible thermosensitive recording material according to claim 1, which is selected from at least one kind of terminal alkyne-based compound represented by the formula: 3. The developer according to claim 1, wherein the developer is represented by the following general formula: (Where X, Y and Z are each independently a single bond or the following chemical formula: Represents one member selected from the divalent group represented by
R ⁴ and R ⁷ independently represent a single bond or a hydrocarbon group having 1 to 30 carbon atoms in total, an aromatic ring, or a heteroaromatic ring. R ⁵ and R ⁶ independently represent a single bond or a hydrocarbon group having a total of 1 to 30 carbon atoms. However, any one of R ⁴ , R ⁵ , R ⁶ , and R ⁷ is a long-chain hydrocarbon having 11 or more carbon atoms. The reversible thermosensitive recording material according to claim 1, which is selected from at least one kind of terminal alkyne-based compound represented by the formula: