JPH07112574A - Thermal recording medium - Google Patents

Abstract

PURPOSE:To obtain a thermal recording medium excellent in the stability of a recording part (developed color image) against light and having absorption in both of a visible part and a near IR part by supporting a diiminoisoindoline derivative having a specific structure on a support using a hydrophobic org. solvent. CONSTITUTION:A diiminoisoindoline derivative represented by the formula (wherein R<1> and R<2> are a halogen atom, an alkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a dialkylamino group, an amino group, a nitro group, an alkylsilyl group, an alkylsilyloxy group or a trifluoromethyl group, m and n are an integer of 0-4 and the sum of m and n is an integer of 0-4) is supported on a support (e.g. resin sheet) using a hydrophobic org. solvent (e.g. toluene). The thermal recording medium thus obtained forms a developed color image especially excellent in light stability and is extremely useful because it has absorption in both of a visible part and a near IR part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording medium, and more particularly to a heat-sensitive recording medium which is most suitable for various prepaid cards such as commuter tickets and telephone cards and which can be optically read.

[0002]

2. Description of the Related Art Conventionally, as a thermal recording medium, Japanese Patent Publication No.
A system using an electron-donating leuco dye as a color former and an electron-accepting phenol compound as a developer is well known, as typified by JP-A 5-14039. This system has been widely used in facsimiles, printers, labels, cards and the like because it has excellent color development sensitivity and can obtain clear images. On the other hand, however, since it utilizes a reversible reaction, it has a drawback that natural fading of a color image and erasing by a plasticizer, oil, water, heat, light, etc. easily occur. In order to overcome this drawback, various studies have been made so far. One of them is an attempt to synthesize phthalocyanine from a phthalocyanine precursor by heat reaction. For example, Japanese Patent Publication No. 58-8357 discloses a thermosensitive coloring layer containing 1-amino-3-iminoisoindolenin or a metal complex salt compound. I'm using it inside. However, this has a problem in the coloring of the metal salt or the metal complex salt itself and the preservability before use. In addition, some metals have an adverse effect on the environment and are difficult to use in practice.

Further, in Japanese Patent Publication No. 4-16353,
As a color forming compound, the following general formula (II)

[0004]

[Chemical 2] [In the formula, A represents NH or (OR) ₂ (wherein R is a lower alkyl group), and Z represents an aromatic compound residue or a heterocyclic compound residue capable of forming a conjugated system with C═NH. ]
The heat-sensitive recording paper using the compound represented by This heat-sensitive recording paper has a problem that the compound (II) is dissolved or pulverized in an aqueous system and applied, and the concentration is low even when heated.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to improve the stability of the recording portion (color image) to light, in addition to having the performance that the thermosensitive recording medium should have, and to further improve the visible portion. -To provide a thermal recording medium having absorption in both the near infrared region.

[0006]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventor has found that the general formula (I)

[0007]

[Chemical 3] [In the formula, R ¹ and R ² are each independently a halogen atom, an alkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a dialkylamino group,
Represents an amino group, a nitro group, an alkylsilyl group, an alkylsilyloxy group, a trifluoromethyl group, and m and n are
Each is an integer of 0 to 4, and the sum of m and n is an integer of 0 to 4. ] It was found that the diiminoisoindoline derivative represented by the formula [4] can meet the purpose when it is supported on a support using a hydrophobic organic solvent, and the present invention was completed based on this finding.

That is, according to the present invention, since the diiminoisoindoline derivative is used and dissolved or dispersed / coated with a hydrophobic organic solvent, a clear color image is obtained without decomposition before thermal color development. The reflection spectrum is shown in FIG.
As shown in (Example 1) and FIG. 3 (Example 5), it is shown that both visible reading and near infrared reading are possible. This reflection spectrum is based on the formation of a phthalocyanine compound, and indicates that the diiminoisoindoline derivative (that is, the phthalocyanine precursor) reacts only by heating to obtain a phthalocyanine compound.

The minimum position of the reflection spectrum of the obtained phthalocyanine is near 680 nm in the case of non-substitution,
When an alkyl group, an alkoxy group, an alkylthio group, or an arylthio group was introduced as a substituent, it was possible to shift to the long wavelength side in this order. Also, when an electron donating substituent such as a trifluoromethyl group or a nitro group was introduced, it was possible to shift to the short wavelength side.

The diiminoisoindoline derivative which is a phthalocyanine precursor is colorless or light-colored and does not react due to factors other than heat. Therefore, the problem of background coloration observed in a reaction system using a fluoran dye and bisphenol A occurs. I don't get it.

The thermosensitive recording medium of the present invention enables visible recording and near-infrared recording at the same time.
It can also be used in combination with metal thin film recording.

The structure of the thermosensitive recording medium of the present invention will be described below by taking the case of having a protective film as an example.

FIG. 1 shows a thermosensitive recording medium comprising a support 1, a thermosensitive coloring layer 2 and a protective film 3. In the figure, the protective film is shown covering the entire side surface of the thermosensitive recording medium, but in order to fulfill the original purpose of protecting the thermosensitive coloring layer, the support may be a little hidden or even the lower part of the support. ,
That is, the entire surface of the thermal recording medium may be covered.

The support is preferably a resin sheet, but particularly preferably a PET sheet, an epoxy resin sheet, a polyvinyl chloride sheet, a polyester sheet, or a polycarbonate sheet.

The thermosensitive coloring layer basically comprises a diiminoisoindoline derivative and a binder. A binder solution is prepared by dissolving the binder in a hydrophobic organic solvent. The diiminoisoindoline derivative is dissolved in this binder solution. If it does not melt, crush and disperse with an attritor or sand mill. The heat-sensitive coating liquid thus obtained is applied to a support and dried. The coating amount is about 5 g / after drying
made to be m ^2.

As the binder, alkyd resin, vinyl chloride resin, urethane resin, xylene resin, phenol resin, coumarone resin, vinyltoluene resin, terpene resin, vinyltoluene / butadiene copolymer resin, vinyl / isobutylether copolymer resin Etc. can be used.

As a solvent for dissolving the binder, a hydrophobic organic solvent such as toluene, n-hexane, cyclohexane, n-octane or ethylcyclohexane is preferably used.

As the substituent of the diiminoisoindoline derivative used in the present invention, in the case of a halogen atom, a fluorine atom, a chlorine atom, a bromine atom or an iodine atom can be used, but a chlorine atom is preferable. The alkyl carbon number of the alkyl group, alkoxy group, alkylthio group, dialkylamino group, alkylsilyl group and alkylsilyloxy group is preferably 1 to 12, more preferably 1 to 4. As the aryl group of the aryloxy group and the arylthio group, a phenyl group, a 4-t-butylphenyl group and a naphthyl group are particularly preferable.

Specific examples of preferred diiminoisoindoline derivatives include 1,3-diiminoisoindoline,
1,3-diimino-5-methylisoindoline, 1,3
-Diimino-5-t-butylisoindoline, 1,3-
Diimino-5-t-amylisoindoline, 1,3-Diimino-5-t-octylisoindoline, 1,3-Diimino-4,5,6,7-tetrachloroisoindoline, 1,3-Diimino-4 -Methoxyisoindoline,
1,3-diimino-4-ethoxyisoindoline, 1,
3-diimino-4-butoxyisoindoline, 1,3-
Diimino-4- (3-methylbutoxy) isoindoline, 1,3-diimino-4- (2,4-dimethyl-3-)
Pentyloxy) isoindoline, 1,3-diimino-
4- (2,6-Dimethyl-4-heptyloxy) isoindoline, 1,3-diimino-4- (4-methyl-2-)
Pentyloxy) isoindoline, 1,3-diimino-
4- (3-methyl-1-butyloxy) isoindoline, 1,3-diimino-4- (1,3-dimethyl-1-)
Butyloxy) isoindoline, 1,3-diimino-4
-(1-methyl-1-butyloxy) isoindoline,
1,3-Diimino-4- (2-methyl-3-pentyloxy) isoindoline, 1,3-Diimino-4- (1,
2-dimethyl-1-pentyloxy) isoindoline,
1,3-Diimino-4- (2,4-dimethyl-3-hexyloxy) isoindoline, 1,3-Diimino-4-
(2-methyl-3-hexyloxy) isoindoline,
1,3-Diimino-4- (4-t-butylcyclohexyloxy) isoindoline, 1,3-Diimino-4-
(3,5-Dimethylcyclohexyloxy) isoindoline, 1,3-diimino-4,7-bis (3-methyl-)
1-Butyloxy) -5,6-dichloroisoindoline, 1,3-diimino-4,7-bis (1-methyl-1)
-Butyloxy) -5,6-dichloroisoindoline,
1,3-Diimino-4,7-bis (1,3-dimethyl-
1-butyloxy) -5,6-dichloroisoindoline,

1,3-Diimino-4,5,6,7-tetraphenoxyisoindoline, 1,3-Diimino-4,
5,6,7-tetranaphthyloxyisoindoline,
1,3-diimino-4,7-diphenoxy-5,6-dichloroisoindoline, 1,3-diimino-4,7-dinaphthyloxy-5,6-dichloroisoindoline,
1,3-Diimino-4,5,6,7-tetraphenylthioisoindoline, 1,3-Diimino-4,5,6,7
-Tetranaphthylthioisoindoline, 1,3-diimino-4,7-diphenylthio-5,6-dichloroisoindoline, 1,3-diimino-4,7-dinaphthylthio-5,6-dichloroisoindoline, 1,3-Diimino-4,5,6,7-tetracyclohexylthioisoindoline, 1,3-Diimino-4,5,6,7-tetrakis (4-t-butylphenylthio) isoindoline,

1,3-Diimino-4-nitroisoindoline, 1,3-Diimino-4-dimethylaminoisoindoline, 1,3-Diimino-4-diethylaminoisoindoline, 1,3-Diimino-4-di- n-Butylaminoisoindoline, 1,3-Diimino-4-trimethylsilylisoindoline, 1,3-Diimino-4-triethylsilylisoindoline, 1,3-Diimino-4-trimethylsilyloxyisoindoline, 1,3-Diimino -4-triethylsiluloxyisoindoline, 1,
3-diimino-4-trifluorooxyisoindoline, 1,3-diimino-5-nitroisoindoline,
1,3-Diimino-5-dimethylaminoisoindoline, 1,3-Diimino-5-diethylaminoisoindoline, 1,3-Diimino-5-di-n-butylaminoisoindoline, 1,3-Diimino-5- Trimethylsilylisoindoline, 1,3-diimino-5-triethylsilylisoindoline, 1,3-diimino-5-trimethylsilyloxyisoindoline, 1,3-diimino-
5-triethylsilyloxyisoindoline, 1,3-
Diimino-5-trifluoromethylisoindoline, and particularly preferably compound 1 represented by the following formula:
~ 16.

[0022]

[Chemical 4]

The above diiminoisoindoline derivative is
It was synthesized by the following method.

Compound 1 is converted into imide or amide from phthalic acid by a known method, and this is treated with thionyl chloride in dimethylamide to give phthalonitrile, which is added to ammonia in the presence of sodium methoxide in methanol. Was obtained.

Compounds 2 to 4 were alkylated from orthoxylene by Friedel-Crafts reaction and then oxidized with potassium permanganate to give phthalic acid derivatives. Less than,
The corresponding diiminoisoindoline derivative was obtained by the same production method as for compound 1.

Compounds 5 to 10 were reacted with the corresponding alcohols via imide, amide and nitrile by a known method from 3-nitrophthalic acid to obtain corresponding diiminoisoindoline derivatives.

Compounds 11 to 13 were obtained by reducing dichlorodicyanobenzoquinone, alkylating it with a corresponding alkylating agent, and then reacting it with ammonia in the presence of sodium methoxide in methanol as in Compound 1.

Compounds 14 to 16 were obtained by reacting tetrachlorophthalic anhydride with mercaptans to give the corresponding tetra-substituted phthalic anhydride, and then the diiminoisoindoline derivative by the above method.

For the protective layer, urethane resin, polyester resin, vinyl resin, epoxy resin, acrylic resin can be used. A phthalic acid ester, a fatty acid ester, an orthophosphoric acid ester, or the like can be added to these resins as a plasticizer, and oleyl amide for imparting lubricity,
Stearyl amide, silicone, etc. can be added. In addition, acrylic, epoxy, or polyester UV curable resins can be used to reduce the amount of solvent used.

A sensitizer may be added to the thermosensitive color developing layer in order to improve the color developing sensitivity. The sensitizer has a melting point of 70.
A colorless heat-fusible substance having a temperature of 120 ° C can be used.

Further, another thermosensitive coloring material can be used in combination in the thermosensitive coloring layer. In that case, for example, when a leuco dye and a color developer are used in combination, those which are insoluble or hardly soluble in the hydrophobic organic solvent are preferable in order to suppress background color formation.

[0032]

EXAMPLES Next, the present invention will be described more specifically by way of examples. All parts are parts by weight.

(Example 1) 2 parts of (Compound 1), acrylic resin "ALMATEX" (trade name: manufactured by Mitsui Toatsu Chemical)
1 part and 8 parts of toluene were ground with a sand mill for 2 hours to obtain a heat-sensitive coating liquid.

This heat-sensitive coating solution was applied onto a PET film using a Meyer bar so that the dry coating amount was 4 g / m ^2, and dried to form a heat-sensitive coloring layer.

An ultraviolet curable resin (made by Morohoshi Ink Co., Ltd.) of 2 g /
UV-offset printing was carried out so as to obtain m ^2, and the coating was cured by irradiation with a high-pressure mercury lamp to form a protective film to obtain a thermal recording material.

Example 2 Example 1 is repeated except that (Compound 2) is used instead of (Compound 1) in Example 1.
The same operation as above was performed to obtain a thermosensitive recording medium.

(Example 3) Example 1 was repeated except that (Compound 3) was used in place of (Compound 1) in Example 1.
The same operation as above was performed to obtain a thermosensitive recording medium.

Example 4 Example 1 was repeated except that (Compound 4) was used instead of (Compound 1) in Example 1.
The same operation as above was performed to obtain a thermosensitive recording medium.

Example 5 Example 1 was repeated except that (Compound 5) was used in place of (Compound 1) in Example 1.
The same operation as above was performed to obtain a thermosensitive recording medium.

Example 6 Example 1 is repeated except that (Compound 6) is used instead of (Compound 1) in Example 1.
The same operation as above was performed to obtain a thermosensitive recording medium.

Example 7 Example 1 is repeated except that (Compound 7) is used instead of (Compound 1) in Example 1.
The same operation as above was performed to obtain a thermosensitive recording medium.

Example 8 Example 1 is repeated except that (Compound 8) is used instead of (Compound 1) in Example 1.
The same operation as above was performed to obtain a thermosensitive recording medium.

(Example 9) Example 1 was repeated except that (Compound 9) was used in place of (Compound 1) in Example 1.
The same operation as above was performed to obtain a thermosensitive recording medium.

Example 10 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that (Compound 10) was used instead of (Compound 1) in Example 1.

Example 11 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that (Compound 11) was used instead of (Compound 1) in Example 1.

(Example 12) A thermosensitive recording medium was obtained in the same manner as in Example 1 except that (Compound 12) was used instead of (Compound 1) in Example 1.

Example 13 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that (Compound 13) was used instead of (Compound 1) in Example 1.

(Example 14) A thermosensitive recording medium was obtained in the same manner as in Example 1 except that (Compound 14) was used instead of (Compound 1) in Example 1.

Example 15 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that (Compound 15) was used instead of (Compound 1) in Example 1.

Example 16 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that (Compound 16) was used instead of (Compound 1) in Example 1.

Comparative Example 1 2 parts of (Compound 1) and 9 parts of 10% aqueous polyvinyl alcohol solution were ground for 2 hours in a sand mill to obtain a heat-sensitive coating solution. This heat-sensitive coating liquid was applied onto high-quality paper using a Meyer bar so that the dry coating amount was 4 g / m ^2, and dried to obtain a heat-sensitive recording medium.

(Evaluation) Examples 1, 2 and Comparative Example 1
With respect to the thermosensitive recording medium manufactured in 1., the color density and the light resistance of the color image were examined. The results are shown in Table 1.

Color images are recorded on each thermosensitive recording medium by 2
It was obtained by contacting an iron at 00 ° C. for 3 seconds.

Macbeth densitometer (TR-254 type)
And the OD value when using a blue filter.

The light resistance was represented by the residual rate after irradiation with UV carbon arc (manufactured by Suga Test Instruments Co., Ltd.) for 8 hours, 16 hours and 24 hours, respectively.

Residual rate (%) = (colored image density after test / colored image density before test) × 100

[0057]

[Table 1] In addition, the heat-sensitive recording materials produced in Examples 1 to 16 have 200
Table 2 shows the wavelength of the minimum value of the reflection spectrum of the color image obtained by contacting with an iron at 3 ° C. for 3 seconds.

[0058]

[Table 2] The wavelength of the minimum value of the reflection spectrum is the self-recording spectrophotometer UV.
-3100 (manufactured by Shimadzu Corporation) was used for measurement.

[0059]

As is clear from Table 1, the thermosensitive recording medium of the present invention is particularly excellent in the stability of the color image to light and has absorption in both the visible region and the near infrared region. Is very useful.

[Brief description of drawings]

FIG. 1 is a sectional view of a thermal recording medium of the present invention.

2 is a reflection spectrum of a color image of the thermosensitive recording medium obtained in Example 1. FIG.

FIG. 3 is a reflection spectrum of a color image of the thermosensitive recording medium obtained in Example 5.

[Explanation of symbols]

 1 support 2 thermosensitive coloring layer 3 protective layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Bunji Sawano 1-43 Minami 1-chome, Yugemachi, Yao City, Osaka Prefecture Yamamoto Kasei Co., Ltd.

Claims (3)

[Claims] 1. A compound represented by the general formula (I): [In the formula, R ¹ and R ² are each independently a halogen atom, an alkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a dialkylamino group,
Represents an amino group, a nitro group, an alkylsilyl group, an alkylsilyloxy group, a trifluoromethyl group, and m and n are
Each is an integer of 0 to 4, and the sum of m and n is an integer of 0 to 4. ] The diiminoisoindoline derivative shown by these was made to carry on the support body using the hydrophobic organic solvent, The thermosensitive recording medium characterized by the above-mentioned. 2. The heat-sensitive recording medium according to claim 1, wherein the support is a resin sheet. 3. The thermosensitive recording medium according to claim 1, wherein the diiminoisoindoline derivative layer carried on the support is covered with a protective film.