JPH11301112A - Reversible thermal recording body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a reversible thermal recording body having high contrast, good preservability of images, and stable red coloring system under a high temperature and high humidity. SOLUTION: The thermal recording layer has a sheet-like support and a thermal recording layer containing an achromatic or hypochromic dye precursor formed on the sheet-like support, and a developing agent to thermally color and decolor this, wherein the dye precursor includes at least one red coloring dye precursor selected from 3-diethylamino-7-phenoxyfluorane and 3-(N-ethyl- phenoxyfluorane and 3-(N-ethyl-N-isoamylamino)-7-phenoxyfluorane.

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, there is a problem that visibility in a dark place is poor. In addition, in general, a white image is recorded on a colored background, and it is difficult to obtain a so-called paper-like recording medium on which a colored image is recorded 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-5-124360 and JP-A-6-2
No. 10954 discloses a method using an organic phosphoric acid compound having a long-chain alkyl group or a phenolic compound as a color developer. However, when erasing, there are drawbacks that the color may not be sufficiently erased, and the storability 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 a practically satisfactory one has not yet been obtained.

As a reversible thermosensitive recording medium overcoming these problems, the present inventors have previously developed a reversible thermosensitive recording medium using a compound having a long-chain alkyl group and a sulfonyl (thio) urea group as a color developer. Proposed (Japanese Patent Laid-Open No. 9-272261)
No.). This reversible thermosensitive recording medium uses a small device, forms a color-developed image on a white background, is capable of coloring and decoloring only by a difference in heating conditions, and has a high contrast.

However, no matter which of the above-mentioned developers is used, there is a problem that a color image using a red-coloring dye precursor is easily decolored under high temperature and high humidity. is there. An object of the present invention is to obtain a red-colorable reversible thermosensitive recording medium that is stable under high temperature and high humidity.

[0007]

The present invention employs the following configuration in order to solve the above-mentioned problems. That is, the present invention
"Heat-sensitive recording layer comprising a sheet-shaped support and a heat-sensitive recording layer formed on the sheet-shaped support and containing a colorless or pale-colored dye precursor, and a developer for reversibly coloring and decoloring the same. In the recording, the dye precursor is 3-diethylamino-7-phenoxyfluoran and 3- (N
-Ethyl-N-isoamylamino) -7-phenoxyfluoran, characterized by containing at least one red color-forming dye precursor selected from the group consisting of:
It is.

In the present invention, as the color developer, the following general formula (I), general formula (II) or general formula (III)
It is desirable to use one containing

[0009]

Embedded image (However, R ₁ represents a member selected from a naphthyl group or a phenyl group substituted by a hydrogen atom, a halogen atom, a lower alkyl group and a lower alkoxy group;
₁ is the following chemical formula:

Embedded image Represents one member selected from the divalent group represented by
Represents an integer of 10 to 29. At least one aromatic compound represented by the formula:

[0010]

Embedded image (Where Y ₂ is the same as Y ₁ and m represents an integer of 10 to 29).

[0011]

Embedded image (Where p represents an integer of 10 to 29).

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The reversible thermochromic recording and decoloring method for a reversible thermosensitive recording material according to the present invention is described in which a thermosensitive recording layer of the recording material is heated to color-record an image, and this recording is used. Then, the color recording image can be erased by heating the thermosensitive recording layer at a temperature lower than the color development heating temperature.

In the reversible thermosensitive recording medium of the present invention, the thermosensitive recording layer containing the dye precursor and the color developer rapidly develops a color by heating, and the developed state is maintained at room temperature by rapid cooling. 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 mechanism of this decolorization is not clear, when the color former is heated below the color development temperature, the long-chain alkyl groups in the color developer are oriented to induce crystallization of the color developer, and the dye and the color developer are heated. It is considered that the colorant separates and decolorizes. 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 performed by a thermal head or the like, which is easy to cool quickly after heating.
This 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 rate. The temperature holding time at the time of decoloring is preferably 0.1 second or more.

As a specific example of the compound used as a color developer in the reversible thermosensitive recording medium of the present invention, a compound represented by the following chemical formula is preferable. These compounds may be used alone or in combination of two or more.

[0015]

Embedded image

[0016]

Embedded image

[0017]

Embedded image

[0018]

Embedded image

The length of the long-chain alkyl group of the color developer according to the present invention must be 11 or more.
The following is preferred. In that area, 14-21
Is more preferable. If the number of carbon atoms is less than 11, the decoloring ability does not reach a practical level, and if it exceeds 30, the color developing ability may be reduced.

Further, in the present invention, a conventionally known color developer comprising a phenol or an organic acid and a sulfonyl (thio) urea-based aromatic compound having no long-chain alkyl group as long as the desired effect is not impaired. Can be used in combination with the sulfonylurea developer having a long-chain alkyl group according to the present invention.

Examples of these known developers include, for example, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 1,1-bis (4-hydroxyphenyl) -1-phenylethane, , 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), p
-Benzyl benzoate (JP-A-52-1404)
No. 83), bisphenol S, 4-hydroxy-
4'-isopropyloxydiphenyl sulfone (JP-A-60-13852), 1,1-di (4-hydroxyphenyl) cyclohexane, 1,7-di (4-hydroxyphenylthio) -3,5-dioxa Heptane (JP-A-59-52694), 3,3'-diallyl-
4,4'-dihydroxydiphenyl sulfone (JP-A-6
0-208286).

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, and these compounds promote the decoloration reaction in addition to the ability of a reversible thermosensitive recording medium to develop high-density color by 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. However, the addition of the zinc salt increases the decoloring density as the color is repeatedly formed and decolored, and the erasing of the color image may be incomplete. Therefore, the content of the zinc salt is determined by the dry weight of the heat-sensitive recording layer. Is preferably 1% by weight or less.

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. The content of the sensitizer of the present invention is generally 5 to 5 times the dry weight of the heat-sensitive recording layer.
It is preferably 0% by weight. When the content of the sensitizer is less than 5% by weight, the effect of accelerating the decoloring is insufficient.
When used in a large amount exceeding the weight%, the color density may be insufficient.

Further, the heat-sensitive recording layer is formed of a phenol, an organic acid, or a sulfonyl (thio) having no long-chain alkyl group.
When a conventionally known color developer comprising a urea-based aromatic compound is contained, its content is preferably 10% by weight or less of the weight of the heat-sensitive recording layer. Phenols, organic acids,
Alternatively, if the content of a conventionally known color developer comprising a sulfonyl (thio) urea-based aromatic compound having no long-chain alkyl group is more than 10% by weight, the decoloring reaction is inhibited, and the color-developing portion and the decoloring portion May decrease in contrast.

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
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. Further, a coating layer such as a protective layer or a printing layer can be formed on the reversible thermosensitive coloring layer in order to improve heat resistance, printing suitability, and repeated durability of 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.

[0032]

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 A: Ingredients Amount (parts) 3-diethylamino-7-phenoxy sihr Oran 20 Polyvinyl alcohol - using a sand grinder Le 10% solution 10 Water 70 The composition, average particle size of 1
It was pulverized until it became not more than μm.

[0034] (2) Preparation of Dispersion B: Ingredients Amount (parts) N-(2-naphthylsulfonyl benzenesulfonyl) -N '- [4- (n- octadecanoylamino) phenyl] urea (Compound No.3 20) Polyvinyl alcohol 10% solution 10 Water 70 The above composition was prepared by using a sand grinder to give an average particle size of 1
It was pulverized until it became not more than μm.

[0035] (3) Preparation Ingredients Amount of Dispersion C (parts) [1,4-bis {2- (4-Mechirubenjiro) ethoxy}] benzene 20 Polyvinyl alcohol - le 10% solution 10 Water 70 The composition Using a sand grinder, the average particle size is 1
It was pulverized until it became not more than μm.

(4) Formation of reversible thermosensitive recording layer: 75 parts of solution A, 150 parts of solution B, 75 parts of solution C, calcined clay 30
Parts, 2 parts of a 25% paraffin wax emulsion and 100 parts of a 10% aqueous polyvinyl alcohol solution were mixed and stirred to obtain a coating solution. This coating solution was applied onto one surface of a support so that the coating amount after drying was 5.0 g / m ^2, and dried to form a reversible thermosensitive recording layer.

(5) Formation of an intermediate layer: 5 parts of a kaolinite clay dispersion (solid content: 60%) and 200 parts of a carboxylic acid-modified polyvinyl alcohol aqueous solution (solid content: 10%) are mixed, mixed and stirred to form an intermediate layer. A coating solution was prepared. This coating solution was applied onto the heat-sensitive recording layer described in the above item (4) so that the coating amount after drying was 1.5 g / m ^2, and dried to form an overcoat layer.

(6) Super calender treatment: The heat-sensitive recording material obtained as described above is treated with a super calender, and the smoothness of the surface of the heat-sensitive recording layer is 3000.
It was adjusted to ５5000 seconds to obtain a reversible thermosensitive recording medium.

(7) Formation of overcoat layer: polyester acrylate (Aronix M-8, manufactured by Toagosei Co., Ltd.)
030), 40 parts of polyester acrylate (manufactured by Toagosei Co., Aronix M-6200) and 20 parts of calcium carbonate (manufactured by Bihoku Powder Chemical Industry, Ryton A) are mixed and stirred, and the intermediate layer according to the above (5) is stirred. On top of 2.
Coating was performed so as to be 5 g / m ² . An oxygen concentration of 300 ppm or less in an electron beam irradiation chamber and an acceleration voltage of 175 were applied to the obtained coating layer.
An electron beam was irradiated under the conditions of kV and an absorbed dose of 3 Mrad to form an overcoat layer and obtain a reversible thermosensitive recording medium.

(8) Test for Color Development and Decoloring The reversible thermosensitive recording medium thus obtained was subjected to a printing voltage of 21.7 V and a printing pulse of 1.0 ms by using a thermal coloration tester THPMD manufactured by Okura Electric. Printed under the following conditions. The print color density was measured with a Macbeth reflection densitometer RD-914. Further, the color-developed sample was heated at 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, and the decoloring density was measured using a Macbeth reflection densitometer RD-9.
Measured at 14. Table 1 shows the test results.

(9) Heat resistance test: After measuring the print color density in the same manner as in the color test of the above item (8), the obtained color sample was allowed to stand at 50 ° C. for one day to determine the color density. It measured similarly. At this time, the storage stability of the image area was evaluated by the image storage ratio: (color density after standing at 50 ° C. for one day) / (color density immediately after printing). Table 1 shows the test results.

(10) Moisture resistance test: After measuring the print color density in the same manner as in the color test of item (8) above, the obtained color sample was allowed to stand at 40 ° C. and 90% humidity for 1 day. The color density was measured in the same manner. Image preservation rate at this time: (coloring density after leaving at 40 ° C. and 90% humidity for 1 day) /
The storage stability of the image area was evaluated by (color density immediately after printing). 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, in preparing Dispersion A, 3- (N-ethyl-N-isoamylamino) -7-phenoxyfluorane was used instead of 3-diethylamino-7-phenoxyfluoran. Table 1 shows the test results.

Example 3 A reversible thermosensitive recording sheet was prepared and tested in the same manner as in Example 1. However, dispersion A
For the preparation of N- (2-naphthylbenzenesulfonyl)
Instead of -N '-[4- (n-octadecanoylamino) phenyl] urea (Compound No. 3), N- (4-hydroxyphenyl) -N'-n-octadecylurea (Compound No. 23)
Was used. Table 1 shows the test results.

<Example 4> A reversible thermosensitive recording sheet was prepared and tested in the same manner as in Example 1. However, dispersion A
For the preparation of N- (2-naphthylbenzenesulfonyl)
Octadecylphosphonic acid (Compound No. 29) was used instead of -N '-[4- (n-octadecanoylamino) phenyl] urea (Compound No. 3). Table 1 shows the test results.

Example 5 A reversible thermosensitive recording sheet was prepared and tested in the same manner as in Example 2. However, dispersion A
For the preparation of N- (2-naphthylbenzenesulfonyl)
Instead of -N '-[4- (n-octadecanoylamino) phenyl] urea (Compound No. 3), N- (4-hydroxyphenyl) -N'-n-octadecylurea (Compound No. 23)
Was used. Table 1 shows the test results.

Example 6 A reversible thermosensitive recording sheet was prepared and tested in the same manner as in Example 2. However, dispersion A
For the preparation of N- (2-naphthylbenzenesulfonyl)
Octadecylphosphonic acid (Compound No. 29) was used instead of -N '-[4- (n-octadecanoylamino) phenyl] urea (Compound No. 3). 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, in preparing Dispersion A, 3,6-bis (diethylamino) fluoran-γ-anilinolactam was used instead of 3-diethylamino-7-phenoxyfluoran. 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, in preparing Dispersion A, 3-piperidino-6-chlorofluorane was used instead of 3-diethylamino-7-phenoxyfluoran. 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, in preparing the dispersion A, rhodamine B-2-chloroanilinolactam was used instead of 3-diethylamino-7-phenoxyfluoran. Table 1 shows the test results.

[0051]

[Table 1]

As is clear from Table 1, Comparative Examples 1 to 3
Although the reversible thermosensitive recording medium containing a dye precursor not included in the present invention has high decoloration properties, the storage stability of a color image under high temperature (50 ° C.) and high humidity (40 ° C., 90% humidity). Was significantly lower. In contrast to the reversible thermosensitive recording materials of these comparative examples, the reversible thermosensitive recording materials containing the dye precursor of the present invention of Examples 1 to 6 have a high coloring density, are excellent in decoloration, and High temperature (50 ° C), high humidity (40 ° C, humidity 90
%), The storage stability of the color image was also very high.

[0053]

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. In particular, a reversible thermosensitive recording medium of a red coloring system which is stable under high temperature and high humidity can be obtained. Therefore, it can be used for a color reversible thermosensitive material that can be used practically.

Claims (4)

[Claims] 1. A heat-sensitive recording layer comprising a sheet-like support, a colorless or light-colored dye precursor formed on the sheet-like support, and a developer for reversibly developing and decoloring the dye precursor. Wherein the dye precursor is at least one red color selected from 3-diethylamino-7-phenoxyfluoran and 3- (N-ethyl-N-isoamylamino) -7-phenoxyfluorane. 1. A reversible thermosensitive recording material comprising a precursor of a coloring dye. 2. The developer according to claim 1, wherein the developer has the following general formula (I): (However, R ₁ represents a member selected from a naphthyl group or a phenyl group substituted by a hydrogen atom, a halogen atom, a lower alkyl group and a lower alkoxy group;
₁ is the following chemical formula: Represents one member selected from the divalent group represented by
Represents an integer of 10 to 29. 2. The reversible thermosensitive recording medium according to claim 1, comprising at least one aromatic compound represented by the formula (1). 3. The developer according to claim 1, wherein the developer has the following general formula (II) in one molecule: (Where Y ₂ is the same as Y ₁ , m represents an integer of 10 to 29), and contains at least one kind of aromatic compound represented by the following formula: Record body. 4. The developer according to claim 1, wherein the developer has the following general formula (III): The reversible thermosensitive recording material according to claim 1, wherein the reversible thermosensitive recording material contains at least one compound represented by the following formula (where p represents an integer of 10 to 29).