JP2002155037A - N,n'-didocosyloxadiamide and reversible heat-sensitive recording material containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new compound useful as a decoloration-promoting agent for reversible heat-sensitive recording materials. SOLUTION: This N,N'-didocosyloxadiamide represented by chemical formula (I). The combination of the N,N'-didocosyloxadiamide represented by chemical formula (I) with a dye precursor and a color developer gives images having a high contrast and excellent storability and can decolor the images in extremely short times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel substance N,
The present invention relates to N'-didocosyl oxadiamide and a decolorizing accelerator for reversible thermosensitive recording containing the same.

More specifically, the present invention relates to a reversible thermosensitive recording material comprising a combination of a dye precursor and a color developing agent capable of reversibly coloring and decoloring the dye precursor. The present invention relates to a novel N, N'-didocosyl oxadiamide which can be erased in a very short time.

[0003] By using the N, N'-didocosyl oxadiamide of the present invention in combination with a dye precursor and a color developer, high contrast and excellent image storability can be obtained, and this image can be produced in an extremely short time. Can be erased.

[0004]

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.

[0005] Against the background of garbage problems and deforestation problems, which 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.

[0006] 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.

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, when erasing, there are drawbacks that the color may not be sufficiently erased, and the storability of the color image may be insufficient.

JP-A-11-70731 and JP-A-11-188969 disclose a compound having a long-chain alkyl group as a decolorizing property improving agent for the phenolic developer compound. The storage stability of the color image in a high temperature environment is insufficient.

The present inventors have also disclosed in Japanese Patent Laid-Open No. 2000-19 / 2000.
No. 8272 proposes a developer having high storability. However, depending on the conditions of coloring and decoloring, when the image is erased within a very short time of about 1 second or less, the image is not sufficiently erased. In some cases, the so-called disappearance remains. It is preferable that the erasing time is shorter in order to shorten the processing time of erasing / printing, and it is desirable that there is no erasure remaining in order to improve the visibility of new printing.

As described above, a number of techniques have been disclosed for a reversible thermosensitive recording medium, but each of them has various drawbacks, and a practically satisfactory one has not yet been obtained. .

[0013]

SUMMARY OF THE INVENTION The present invention provides a novel compound which can solve the above-mentioned problems of the prior art, and by using it, a reversible compound capable of erasing an image in a very short time. A thermosensitive recording medium is provided. When the compound of the present invention is used in combination with a dye precursor and a color developer, image storability is high and color erasing can be performed in a very short time. The reversible thermosensitive recording medium thus obtained can be used as, for example, prepaid cards, point cards, facsimile paper that is used many times, or a display material that does not require energy to hold an image.

[0014]

Means for Solving the Problems The present inventors have found that a reversible thermosensitive recording medium capable of performing coloring and decoloring only by a difference in heating conditions changes from a colored state to a decolored state in a very short time. In order to obtain a reversible thermosensitive recording material, a dye-type reversible thermosensitive recording system utilizing the reaction of a dye with a color developer and a color erasure accelerator was studied as a result. , A novel N, N'-didocosyl oxadiamide, and completed the present invention.

The novel compound of the present invention has the following chemical formula (I):

Embedded image N, N'-didocosyl oxadiamide represented by

The compound of the present invention can be synthesized, for example, by the following reaction formula.

[0017]

Embedded image

The solvent used in the above reaction is not particularly limited as long as it does not inhibit the reaction by reacting with the above (B). Preferred solvents include, for example, tetrahydrofuran, dimethylsulfoxide, dimethylacetamide, dimethylformamide and the like.

In a preferred embodiment of the present invention, the reversible thermosensitive recording medium comprises a sheet-like support, a colorless or pale-color dye precursor formed on the sheet-like support, and a colorless or pale-colored dye precursor. A heat-sensitive recording layer containing a color developer to be decolorized, and as the color developer, the following general formula (I)
I):

Embedded image (Wherein, R ₁ represents a lower alkyl group, an unsubstituted aromatic ring group, or an aromatic ring group substituted with at least one member selected from a lower alkyl group, a halogen atom, and a lower alkoxy group; ₂ represents a divalent hydrocarbon group having a single bond or a carbon number of 1 to 11, R ₃ is .X _1, X ₂ representing a straight-chain aliphatic group of 11 to 30 carbon atoms is a single independently of one another A bond or the following chemical formula:

Embedded image Represents one member selected from the divalent group represented by ), Wherein the heat-sensitive recording layer further comprises at least one aromatic compound represented by the following chemical formula (I):

Embedded image Or a compound represented by the formula:

The reversible thermochromic recording and erasing method of the reversible thermosensitive recording medium according to the present invention is characterized in that the thermochromic 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 coloring image.

In the general formula (II), R ₁ represents a lower alkyl group, an unsubstituted aromatic ring group or a lower alkyl group;
It represents an aromatic ring group substituted by at least one member selected from a halogen atom and a lower alkoxy group. Preferred examples include the following groups.

Embedded image

[0022]

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 mechanism of the color development / decolorization is not clear, the -NH- group represented by the formula (II) in the developer is activated by the adjacent sulfonyl group and carbonyl group, Shows strong color developing ability to leuco dyes, and develops color.On the other hand, when the color forming body is heated below the color developing temperature, long-chain alkyl groups in the color developer are oriented to induce crystallization of the color developer. However, it is considered that the dye and the developer are separated and decolorized. Generally, the heating temperature for coloring is 12
0 to 240 ° C., and the temperature range where decoloration occurs is 60 to 18
0 ° C. and lower than the coloring heating temperature. Generally, coloring is performed by a thermal head or the like, which is easy to rapidly cool after heating.
There is no need to control the cooling rate. The temperature holding time at the time of decoloring is preferably 0.1 second or more.

It is not clear what mechanism the color erasure accelerator acts on the color development / decolorization reaction between the dye and the color developer, but the color erasure accelerator does not It is considered that this affects the mobility of the linear hydrocarbon group of the agent molecule. That is, when the color developing system in the amorphous state is heated to the color erasing temperature range, the color developing system shows fluidity, and it is considered that the linear hydrocarbon groups of the color developer molecules are oriented. Is considered to decrease the viscosity of the coloring system, thereby increasing the mobility of the linear hydrocarbon group of the developer compound molecule, thereby promoting crystallization of the developer and increasing the decoloring rate. .

Specific examples of the aromatic compound used as a developer in the reversible thermosensitive recording medium of the present invention are shown below, but are not limited thereto. These compounds may be used alone or in combination of two or more.

[0025]

Embedded image

In the thermosensitive recording layer of the reversible thermosensitive recording material of the present invention, the compound used as a dye precursor includes:
Examples thereof include 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-
Np-toluidino) -6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 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-chlorofluoran, 3-diethylamino-
6-methylfluoran, 3-cyclohexylamino-6
-Chlorofluorane.

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.

The reversible thermosensitive recording medium according to the present invention can contain a thermofusible substance generally known as a sensitizer in the thermosensitive recording layer. Such sensitizers include, for example, oxalic acid diesters (Japanese Patent Application Laid-Open No. 64-1583) and di (4-methylbenzyl) oxalate (JP-B 5-62597).
JP, JP-A-60-56388), 1,2-bis (m-tolyloxy) ethane (JP-A-60-56588), diphenylsulfone (JP-A-60-15667), p-benzylbiphenyl (JP-A-60-82382). No. 1), 4-
Bis [2- (4-methylbenzyloxy) ethoxy] benzene (JP-A-11-20320).

In the present invention, a conventionally known decoloring accelerator can be used in combination within a range not to impair the desired effect. Examples of such a decoloring accelerator include didodecyl urea, N-stearyl stearamide, hexamethylene bisoleic amide, N, N'-didodecyl oxadiamide, and Japanese Patent Application No. 2000-139248. .

The heat-sensitive recording layer according to the present invention may further contain waxes and pigments within a range not to impair the effects of the present invention, and usually contains a binder. Known waxes such as paraffin, amide-based wax, and bisimide-based wax can be used as the wax.

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.

Examples of the binder include polyvinyl alcohol having various molecular weights and derivatives thereof (eg, acetoacetyl group-modified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, sulfonyl group-modified polyvinyl alcohol, etc.), starch and derivatives thereof (eg, oxidized starch, acetic acid and acetic acid). Vinyl graft starch, aldehyde-modified starch, etc.), cellulose derivatives such as methoxycellulose, carboxymethylcellulose, methylcellulose, 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, styrene / butadiene copolymer, polyacrylic acid, polyacrylate, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / Latexes such as vinyl acetate copolymers and styrene / butadiene / acrylic copolymers can be used. These binders may be used alone or in combination of two or more.

In the heat-sensitive recording layer of the reversible heat-sensitive recording material according to the present invention, the content of the dye precursor is generally preferably from 5 to 40% by weight of the dry weight of the heat-sensitive recording layer, and the content of the developer is included. The ratio 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 color developer is less than 5% by weight, the color development ability becomes insufficient, and
Even when used in a large amount exceeding 0% by weight, the color developing ability is saturated, and there is no particular improvement in the contrast between the coloring density and the erasing density, which may be economically disadvantageous. The content of the decoloring accelerator is generally 1% of the total dry weight of the heat-sensitive recording layer.
Preferably, it is about 50% by weight. If the content of the decoloring accelerator is less than 1% by weight, the effect of accelerating decoloring is insufficient,
When used in a large amount exceeding 50% by weight, the color density may be insufficient.

When waxes and pigments are contained in the heat-sensitive recording layer, the content thereof is 2 to 20% by weight,
Preferably, the content of the binder is 5 to 50% by weight.

The support used in the reversible thermosensitive recording medium according to the present invention is coated on paper (including acidic paper and neutral paper) which has been used for conventional thermosensitive recording media, and coated with a pigment, latex or the like on the surface. In addition to coated paper, laminated paper, synthetic paper made of polyolefin resin, plastic films such as polyolefin, polyester, and polyimide, glass plates and conductive rubber sheets can be selected. On at least one surface of such a support, a coating solution containing a mixture of the above-mentioned required components is applied and dried to produce a reversible thermosensitive recording medium. The coating amount is preferably from 1 to 15 g / m ² in a state where the coating liquid layer has dried, 2 to 10 g / m ² is particularly preferred.

In the reversible thermosensitive recording medium according to the present invention, an undercoat layer may be provided below the reversible thermosensitive coloring layer. Further, a back layer may be provided on the back surface of the reversible thermosensitive recording medium to prevent blocking at the time of contact between the front surface and the back surface, to suppress penetration of water or oil from the back surface, and to control curl.

In the reversible thermosensitive recording medium according to the present invention, a protective layer is formed on the reversible thermosensitive coloring layer in order to improve heat resistance, light fastness, and durability against repeated coloring and decoloring. You can also. The protective layer contains a pigment, a binder, and the like. Further, if necessary, a lubricant such as wax and silicone oil, an ultraviolet absorber and the like can be contained.

In the protective layer, pigments that can be used include, for example, silica, clay, calcined clay, talc,
Inorganic fine powders such as calcium carbonate, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate and surface-treated calcium carbonate and silica; urea-formalin resin; styrene / methacrylic acid copolymer And organic fine powder such as polystyrene resin. As the binder, it is preferable to use a crosslinkable resin such as an electron beam curable resin, an ultraviolet curable resin, and a thermosetting resin.

In order to improve the interlayer adhesion between the protective layer and the reversible thermosensitive recording layer, to provide printability, and to prevent the components of the protective layer from penetrating into the reversible thermosensitive recording layer, reversible thermosensitive recording is performed. An intermediate layer can be formed between the layer and the protective layer. The intermediate layer contains a pigment, a binder, and the like.

In the above-mentioned intermediate layer, pigments and the like which can be used include, for example, silica, clay, calcined clay, talc,
Inorganic fine powders such as calcium carbonate, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate and surface-treated calcium carbonate and silica; urea-formalin resin; styrene / methacrylic acid copolymer And organic fine powder such as polystyrene resin. Examples of the binder include polyvinyl alcohol having various molecular weights and derivatives thereof (eg, acetoacetyl group-modified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, sulfonyl group-modified polyvinyl alcohol, etc.), starch and derivatives thereof (eg, oxidized starch, vinyl acetate graft starch). ,
Aldehyde-modified starch, etc.), methoxycellulose,
Cellulose derivatives such as carboxymethylcellulose, methylcellulose and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, styrene / maleic anhydride Water-soluble polymer materials such as acid copolymer alkali salts, polyacrylamide, sodium alginate, gelatin, and casein, as well as polyvinyl acetate, polyurethane, styrene / butadiene copolymer, polyacrylic acid, polyacrylate, and chloride. Latexes such as vinyl / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer, and styrene / butadiene / acrylic copolymer can be used. These binders may be used alone or in combination of two or more. The invention is not limited to these.

The reversible thermosensitive recording medium according to the present invention can be further processed to enhance the added value, thereby obtaining a reversible thermosensitive recording medium having higher functions. 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.

An apparatus for recording (coloring) and erasing (erasing) an image can be selected from a thermal head, a constant temperature bath, a heating roller, a hot pen, a sheet heating element, a laser beam, an infrared ray, and the like according to the purpose of use. It is possible, but not limited to these.

Next, N, N 'represented by the chemical formula (I)
-Shows a specific method for synthesizing didocosyl oxadiamide.
Note that all solvents used were purified by distillation in advance.

Synthesis Example 1 Synthesis of N, N′-didocosyl oxadiamide Docosylamine (34.
2 g), pyridine (9.9 g), and tetrahydrofuran (500 mL) were added and stirred. Oxalyl chloride (6.4 g) was added thereto, and the mixture was stirred at room temperature for 6 hours.
Thereafter, the reaction solution was poured into a 2 L beaker containing 1 L of water, stirred at room temperature for 2 hours, and filtered by suction. The obtained colorless powder and 500 mL of ethanol were placed in a 1-L eggplant-shaped flask equipped with a reflux condenser,
After heating and refluxing for 2 hours, the mixture was cooled to room temperature and filtered by suction to obtain the desired product (33.1 g).

Synthesis Example 2 Synthesis of N, N'-didocosyl oxadiamide Docosylamine (16.
3 g), pyridine (4.8 g), and tetrahydrofuran (250 mL) were added and stirred, and ethyl chloroglyoxylate (6.8 g) was added thereto, followed by stirring at room temperature for 3 hours. 150 mL of 1N-potassium hydroxide aqueous solution was added thereto, and the mixture was stirred at room temperature for 3 hours, neutralized with 50 mL of 3N-hydrochloric acid, and filtered with suction to obtain a colorless solid. After drying this colorless solid under reduced pressure, docosylamine (16.3 g),
The mixture was placed in a 1-L eggplant-shaped flask together with 1-hydroxybenzotriazole (8.4 g), suspended in 500 mL of tetrahydrofuran, and diisopropylcarbodiimide (6.9 g) was added dropwise thereto, followed by stirring at room temperature for 16 hours. The reaction solution was subjected to suction filtration, and the obtained colorless solid was washed with methanol and dried under reduced pressure to obtain the desired product (31.7).
g) was obtained.

Analytical values of crystals obtained in Synthesis Examples 1 and 2
Was as follows. Melting point: 121 ° C ¹ Results of H-NMR measurement (in heavy tetrahydrofuran)
(The figures are ppm) δ = 0.88 (t, 6H), 1.29 (bs., 76H),
1.52 (m, 4H), 3.20 (dt, 4H), 7.97
(Bs, 2H)Results of IR measurement (KBr tablet method) 3312, 2924, 2849, 1652, 1509,
1472, 1381cm ^-1

[0047]

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.

<Production Example 1 of Reversible Thermosensitive Recording Sheet> A reversible thermosensitive recording sheet was prepared by the following operations (1) to (6). (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 It was pulverized until the particle size became 1.1 μm.

[0049] (2) Sand Dispersion Preparation Ingredients Amount of B (parts) N- acetyl -p- octadecanoylamino benzenesulfonamide (Compound No.1) 20 Polyvinyl alcohol 10% solution 10 Water 70 The composition Using a grinder, pulverization was performed until the average particle size became 1.1 μm.

[0050] (3) Preparation Ingredients Amount of Dispersion C (parts) N, using a sand grinder N'- didocosyl oxa-diamide 20 polyvinyl alcohol 10% solution 10 Water 70 The composition, average particle size of 1 And crushed to 1 μm.

(4) Formation of reversible thermosensitive recording layer 100 parts of dispersion A, 400 parts of dispersion B, and dispersion C1
00 parts and 10% polyvinyl alcohol aqueous solution 2
50 parts were mixed and stirred to obtain a coating solution. This coating solution is
A reversible thermosensitive recording layer was formed on one side of a PET film having a thickness of 150 μm so that the coating amount after drying was 5.0 g / m ² , followed by drying.

(5) Formation of Intermediate Layer 60 parts of a 50% dispersion of kaolinite clay and 200 parts of a 10% aqueous polyvinyl alcohol solution were mixed and stirred to prepare an intermediate layer coating solution. This coating solution was applied onto the heat-sensitive recording layer described in the above item (4) in an amount of 1.5 g / m ² after drying.
And dried to form an intermediate layer.

(6) Formation of protective 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 (5) so that the application 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 a protective layer to obtain a reversible thermosensitive recording sheet.

(7) Color development and color erasure test The reversible thermosensitive recording sheet obtained in this manner was subjected to a printing voltage of 2 using a thermal color development tester THPMD manufactured by Okura Electric.
Printing was performed under the conditions of 1.7 V and a printing pulse of 1.0 ms. The print color density was measured with a Macbeth reflection densitometer RD-914. Further, the color-developed sample was heated using a thermal gradient tester manufactured by Toyo Seiki under the conditions of a heating temperature of 110 ° C., a pressure of 1 kg / cm ² , and a heating time of 0.2 seconds. Measured at -914. Table 1 shows the test results.

(8) Storage test The print color density was measured in the same manner as in the color test (7), and the color sample obtained was allowed to stand at 40 ° C. for 7 days. It measured similarly. At this time, the storage stability of the image area was evaluated by the following formula: image storage ratio: (color density after standing at 40 ° C. for 7 days / color density immediately after printing) × 100 (%). Table 1 shows the test results.

(9) Repetitive Color Forming / Decoloring Test The print coloring density and the color erasing density after repeating the color forming / decoloring test of the above item (7) 20 times were measured by a Macbeth reflection densitometer RD-914. It was measured. Table 1 shows the test results.

<Reversible thermosensitive recording sheet production example 2> A reversible thermosensitive recording sheet was prepared and tested in the same manner as in the reversible thermosensitive recording sheet production example 1. However, in preparing Dispersion B, N-acetyl-p-octadecanoylaminobenzenesulfonamide (Compound No. 1) was used instead of N-acetyl-p-octadecanoylaminobenzenesulfonamide.
Acetyl-p- (7-octadecylaminocarbonyl)
Heptanoylaminobenzenesulfonamide (Compound N
o. 3) was used. Table 1 shows the test results.

<Reversible thermosensitive recording sheet production example 3> A reversible thermosensitive recording sheet was prepared and tested in the same manner as in the reversible thermosensitive recording sheet production example 1. However, in preparing Dispersion B, N-acetyl-p-octadecanoylaminobenzenesulfonamide (Compound No. 1) was used instead of N-acetyl-p-octadecanoylaminobenzenesulfonamide.
Benzoyl-p- (6-octadecylaminocarbonylamino) hexanoylaminobenzenesulfonamide (Compound No. 4) was used. Table 1 shows the test results.

<Example 4 of Production of Reversible Thermosensitive Recording Sheet> A reversible thermosensitive recording sheet was prepared and tested in the same manner as in Production Example 1 of the reversible thermosensitive recording sheet. However, in preparing Dispersion B, N-acetyl-p-octadecanoylaminobenzenesulfonamide (Compound No. 1) was used instead of N-acetyl-p-octadecanoylaminobenzenesulfonamide.
(2-Methylpropanoyl) -p- (7-docosanoylhydrazinocarbonyl) heptanoylaminobenzenesulfonamide (Compound No. 9) was used. Table 1 shows the test results.

<Reversible thermosensitive recording sheet production example 5> A reversible thermosensitive recording sheet was prepared and tested in the same manner as in the reversible thermosensitive recording sheet production example 1. However, in preparing Dispersion B, N-acetyl-p-octadecanoylaminobenzenesulfonamide (Compound No. 1) was used instead of N-acetyl-p-octadecanoylaminobenzenesulfonamide.
{4- [7- (n-docosanoylhydrazinocarbonyl) heptanoylamino] phenylsulfonyl} benzamide (Compound No. 10) was used. Table 1 shows the test results.

<Example 6 of Production of Reversible Thermosensitive Recording Sheet> A reversible thermosensitive recording sheet was prepared and tested in the same manner as in Production Example 1 of the reversible thermosensitive recording sheet. However, in preparing Dispersion B, N-acetyl-p-octadecanoylaminobenzenesulfonamide (Compound No. 1) was used instead of N-acetyl-p-octadecanoylaminobenzenesulfonamide.
{4- [9- (n-docosanoylhydrazinocarbonyl) nonanoylamino] phenylsulfonyl} benzamide (Compound No. 11) was used. Table 1 shows test results
Shown in

<Reversible thermosensitive recording sheet production example 7> A reversible thermosensitive recording sheet was prepared and tested in the same manner as in Reversible thermosensitive recording sheet production example 1. However, in preparing the dispersion A, 3-diethylamino-6-methyl-7-anilinofluoran was used instead of 3-dibutylamino-6-methyl-7-anilinofluoran. Table 1 shows test results
Shown in

<Example 8 of producing a reversible thermosensitive recording sheet> A reversible thermosensitive recording sheet was prepared and tested in the same manner as in Production Example 1 of a reversible thermosensitive recording sheet. However, in preparing dispersion A, 3-di (n-butyl) amino-6-methyl-7-
3- (N-ethyl-N-) instead of anilinofluoran
Isoamylamino) -6-methyl-7-anilinofluoran was used. Table 1 shows the test results.

<Reversible Thermosensitive Recording Sheet Production Example 9> A reversible thermosensitive recording sheet was prepared and tested in the same manner as in Reversible Thermosensitive Recording Sheet Production Example 1. However, in preparing dispersion A, 3-di (n-butyl) amino-6-methyl-7-
3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-) instead of anilinofluoran
Methylindol-3-yl) -4-azaphthalide was used. Table 1 shows the test results.

<Reversible Thermosensitive Recording Sheet Production Example 10> A reversible thermosensitive recording sheet was prepared and tested in the same manner as in Reversible Thermosensitive Recording Sheet Production Example 1. However, formation of the protective layer was performed as follows. UV curable vehicle (manufactured by Dainichi Seika Kogyo Co., Ltd., trademark: Seikabeam PPC-D-9 (revised))
Was applied by an offset printing machine at a dry coating amount of ² g / m ² , and an ultraviolet curing device having one 1.2 KW mercury lamp was applied to this coating layer at a distance of 10 mm from the lamp.
The protective layer was formed by irradiating ultraviolet rays under the conditions of cm and a transfer speed of 15 m / min. Table 1 shows the test results.

<Reversible thermosensitive recording sheet production example 11> A reversible thermosensitive recording sheet was prepared and tested in the same manner as in the reversible thermosensitive recording sheet production example 1. However, in preparing Dispersion B, instead of N-acetyl-p-octadecanoylaminobenzenesulfonamide (Compound No. 1), p
-Octadecanoylaminophenol was used. Table 1 shows the test results.

<Comparative Example 1> A reversible thermosensitive recording sheet was prepared and tested in the same manner as in Production Example 1 of the reversible thermosensitive recording sheet. However, the coating liquid for forming the reversible thermosensitive recording layer is
Without using the dispersion C, 120 parts of the dispersion A and the dispersion B480
Part and 10% polyvinyl alcohol aqueous solution 250
The parts were mixed and adjusted.

Comparative Example 2 A reversible thermosensitive recording sheet was prepared and tested in the same manner as in Production Example 1 of the reversible thermosensitive recording sheet. However, in preparing the dispersion C, N-stearylstearic amide was used instead of N, N'-didocosyloxadiamide. Table 1 shows the test results.

Comparative Example 3 A reversible thermosensitive recording sheet was prepared and tested in the same manner as in Production Example 1. However, in preparing Dispersion C, N, N'-didodecyloxadiamide was used instead of N, N'-didocosyloxadiamide. Table 1 shows the test results.

[0070]

[Table 1]

As is clear from Synthesis Examples 1 and 2, N, N'-didocosyl oxadiamide according to the present invention is a well-identified novel compound. In addition, as is clear from comparison of reversible thermosensitive recording sheet production examples 1 to 11 and comparative examples 1, 2, and 3, the use of the compound of the present invention as a decolorizing accelerator for reversible thermosensitive recording makes it possible to obtain a conventional dye type. It was confirmed that the recording material had higher decolorability and storage property than the reversible thermosensitive recording medium, and was excellent in repetition of coloring and decoloring.

[0072]

The N, N'-didocosyl oxadiamide of the present invention is a novel compound. Further, the reversible thermosensitive recording medium used as the compound of the present invention as a decolorization accelerator has higher decoloration and storage properties than those using a conventional decolorization accelerator, and also has a repeatability of color development and decoloration. Are better. Therefore, it has a very high practical value.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C005 HA17 HA21 HB04 HB14 JC02 LB08 2H026 AA07 AA09 BB02 BB24 DD03 DD43 DD53 FF01 4H006 AA01 AB76 BV22

Claims (3)

[Claims] An N, N'-didocosyl oxadiamide represented by the following chemical formula (I). Embedded image 2. A reversible thermosensitive recording material comprising a compound represented by the following chemical formula (I) as a decolorizing accelerator for reversible thermosensitive recording. Embedded image 3. A heat-sensitive recording layer comprising a sheet-like support, a colorless or pale-color dye precursor formed on the sheet-like support, and a developer for reversibly coloring and decoloring the dye precursor. And further having the following general formula (II): (Wherein, R ₁ represents a lower alkyl group, an unsubstituted aromatic ring group, or an aromatic ring group substituted with at least one member selected from a lower alkyl group, a halogen atom, and a lower alkoxy group; ₂ represents a divalent hydrocarbon group having a single bond or a carbon number of 1 to 11, R ₃ is .X _1, X ₂ representing a straight-chain aliphatic group of 11 to 30 carbon atoms is a single independently of one another A bond or the following chemical formula: Represents one member selected from the divalent group represented by ), Wherein the heat-sensitive recording layer further comprises at least one aromatic compound represented by the following chemical formula (I): A reversible thermosensitive recording medium comprising a compound represented by the formula: