JPS6290283A - Dichroic color forming type thermal recording body - Google Patents

Abstract

PURPOSE:To provide a dichroic color forming type thermal recording body having a simple mechanism and capable of providing a stable permanent image in order to form a dichroic image, by incorporating a colorless or light yellow aromatic diazo compound having a max. absorption wavelength of below a specific length and capable of forming a redish azo dye upon the coupling reaction with 2,3-dihydroxynaphthalene and a yellow aromatic diazo compound having a max. absorption wavelength of a specific length or more and capable of forming a bluish azo dye upon the coupling reaction with 2,3- dihydroxynaphthalene as diazoe compounds. CONSTITUTION:A recording body is constituted by providing a recording layer containing diazo compounds, a coupler, an acid stabilizer, a thermal developer and a polymer binder on a support. As the diazo compounds, a colorless or light yellow aromatic diazo compound capable of forming a redish azo dye upon the reaction with 2,3-dihydroxynaphthalene and low in photosensitivity and having a max. absorption wavelength of below 350nm and a yellow aromatic compound capable of forming a bluish azo dye upon the reaction of 2,3-dihydroxynaphthalene and high in photosensitivity and having a max. absorption wavelength of 350nm or more are contained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a two-color thermosensitive recording material that allows color information to be immediately converted into a two-color image in facsimiles, printers, electronic blackboards, and the like.

Prior Art and Problems Conventionally, as methods for converting color information of two or more colors into hard copies, there are electrostatic recording methods, inkjet methods, thermal transfer methods, leuco dye type thermal methods, and the like. These recording methods have the following drawbacks. For example, in the electrostatic recording method, the apparatus is complicated and large, and consumables such as powder or liquid developer are required, and the associated maintenance management is complicated. The inkjet method has drawbacks such as maintenance such as ink replacement and complicated hardware mechanisms.

On the other hand, the thermal transfer method has a simple mechanism and excellent image stability, but has disadvantages such as requiring replacement of consumables such as ink ribbons, high cost, and requiring maintenance. In addition, the leuco dye type thermosensitive recording method has a simple mechanism,
Although maintenance is easy, in order to use the temperature difference to print two colors (°C), there is always a border of the color on the low temperature side around the r-elephant that is shot at a high temperature, resulting in poor image quality, and furthermore, the color fades in the recording layer. Because it contains agents, it has the disadvantage of not providing stable images or preserving unrecorded paper.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned drawbacks, and provides a two-color thermosensitive recording medium that is easy to maintain and can obtain color images using a recording method with a simple mechanism, and has good image quality and storage stability. With the goal.

Summary of the Invention In order to achieve the above object, the two-color thermosensitive recording material of the present invention comprises a diazo compound, a coupler, an acid stabilizer, a thermal developer, a polymer binder, etc. on a support. In the recording medium provided with the recording layer, the diazo compound is colorless or pale yellow and has a maximum absorption wavelength of less than 350% m1,
An aromatic diazo compound capable of forming a red azo dye through a coupling reaction with at least 2,3-dihydroxynaphthalene, and an aromatic diazo compound that is yellow in color and has a maximum absorption wavelength of 350*- or more and is coupled with at least 2,3-dihydroxynaphthalene. This is a two-color thermosensitive recording material characterized by containing at least an aromatic diazo compound that can react to form a blue-based azo dye.

The two-color thermosensitive recording material, which is a detailed explanation of the invention, will be described in detail below.

A heat-sensitive recording material using a diazo compound is a recording material in which the basic recording composition is a diazo compound, a coupler, and a heat developer on a support. In such a recording medium, thermal energy causes phase changes in the thermal developer such as decomposition, dissociation, and melting, and the coupling reaction between the diazo compound and the coupler occurs in the recording layer in an alkaline atmosphere (or coupling-active atmosphere). An image of the raised azo dye is formed, and then the entire surface is irradiated with light energy to decompose the unreacted diazo compound.
It loses its coloring ability and fixes to form a permanent azo dye image. The spectral characteristics of this diazo compound, that is, the maximum absorption wavelength, ranges over a wide range from the ultraviolet region to the visible region depending on the type of diazo compound, and the photosensitivity also changes. On the other hand, the color tone of the azo dye can be changed arbitrarily by combining the diazo compound and the coupler. Further, even if the same coupler is used, the color tone can be changed by changing the diazo compound.

The present inventor has developed an aromatic diazo compound and 2 as a coupler.
, discovered that the azo dye obtained by reaction with 3-dihydroxynaphthalene is divided into two colors, one in the red range and the other in the blue range, and that the photosensitivity of this aromatic diazo compound is due to its chemical structure. Ta. Among aromatic diazo compounds, those with an electron-donating group at the para position or the para position are stable and can be stored well, and those with a positive polar group such as dialkylamine, alkoxy, or morpholine at the para position. have high photosensitivity, whereas those with negative polar groups have low photosensitivity. In other words, regarding the relationship between color tone and photosensitivity, aromatic diazo compounds that form red-based azo dyes by reaction with 2,3-dihydroxynaphthalene have low sensitivity, with an extremely thick absorption wavelength of less than 350%W. .

On the other hand, an aromatic diazo compound that forms a blue-based azo dye by reaction with 2,3-dihydroxynaphthalene has high photosensitivity and has an extreme absorption wavelength of 3501 or more.

By using at least two or more types of aromatic diazo compounds that can react with the same coupler to form azo dyes with different color tones, the two-color heat-sensitive recording material of the present invention has a difference in spectral characteristics and photosensitivity. I was able to complete it.

That is, the present invention provides a recording medium in which a recording layer comprising a diazo compound, a coupler, an acid stabilizer, a thermal developer, a polymeric binder, etc. is provided on a support, and the diazo compound contains at least 2, It is a colorless to pale yellow aromatic diazo compound with a low photosensitivity and an ultra-thick absorption wavelength of 350 s @ ungrooved colorless to pale yellow aromatic diazo compound that can react with 3-dihydroxynaphthalene to form a red-based azo dye (hereinafter referred to as is also called aromatic diazo compound A) and at least 2゜3-dihydroxynaphthalene to form a blue-based azo dye. This invention relates to a two-color thermosensitive recording material containing an aromatic diazo compound (hereinafter also referred to as aromatic diazo compound B in some cases), and image formation thereof is obtained by the following steps.

1. First, the selected aromatic diazo compound A and aromatic diazo compound B are reacted with the coupler by thermal energy to form a mixed color azo dye image.

2. Next, the aromatic diazo compound B is photodecomposed by specific actinic rays of 3501 or more on the entire surface and loses its coloring ability.

3. Next, when thermal energy is applied to the unimaged area, the aromatic diazo compound A, which has not lost its coloring ability, reacts with the coupler to form a monochromatic azo dye.

4. Finally, the aromatic diazo compound A is photodecomposed by specific actinic rays of less than 350 nm and loses its coloring ability.

The above recording method, that is, thermal printing → optical fixing → thermal printing →
Since images are formed by optical fixation, two-color images with different tones are formed using a recording method with a simple mechanism, and since they can be completely fixed, the stability of the resulting images is excellent.

However, in this recording method, the final step in which the aromatic diazo compound A is photodecomposed by a specific actinic ray and loses its coloring ability may be omitted.

This is because this diazo compound is colorless or pale yellow, so it does not impair the whiteness of the surface of the recording layer after recording and does not significantly reduce the stability of the image. That is, in the recording medium of the present invention, optical fixing in the final step may be omitted depending on the purpose of use.

Further, specific examples of the two-color thermosensitive recording material of the present invention and the recording method using the same are shown in the drawings, in which 1 is the recording layer, 2 is the support, 3 is the coupler, and 4.5 is the route. Aromatic diazo compounds are shown respectively. In the illustrated example, coupler 3 is 2,3-dihydroxynaphthalene, aromatic diazo compound A4 is 4-diazo-3-methoxynitrobenzene, and aromatic diazo compound B5 is 4-diazo-I-
04- which is morpholino-2,5-dibutoxybenzene
Diazo-3-methoxynitrobenzene reacts with 2,3-dihydroxynaphthalene to form a red azo dye. 4-Diazo-1-morpholino-2,5-dibutoxybenzene is also an aromatic diazo compound that reacts with 2,3-dihydroxynaphthalene to form a blue azo dye.
-Diazo-3-methoxynitrobenzene and 4-diazo-
The recording method for 1-morpholino is to first apply thermal energy to a colored azo dye and 4-diazo-1-morpholino-
When 2,5-dibutoxybenzene and 2,3-dihydroxynaphthalene react, a blue azo dye is simultaneously produced (
By irradiating with light of λmax=420s+a), 4-diazo-1-morpholino-2,5-dibutoxybenzene is photodecomposed into an inactive compound. (Figure 2,
(See step 2) Next, when thermal energy is applied to the unpainted 1st image, 4-diazo-3-methoxynitrobenzene, which has not lost its coloring ability, reacts with 2°3-dihydroxynaphthalene, producing a red 74-diazo-3 - Methoxynitrobenzene is photolyzed by actinic light from a high-pressure mercury lamp into an inert compound, forming a two-color permanent image of purple and red. (See FIG. 2, Step 4) The recording material used in the present invention will be described in detail below.

Used in the present invention, has low photosensitivity and has an extremely thick absorption wavelength of 35
Aromatic diazo compounds having less than 0% I11 and capable of reacting with at least 2,3-dihydroxynaphthalene to form red-colored azo dyes have the general formula ArN2X
It is a colorless to pale yellow diazonium salt represented by , and is a compound that can be decomposed by actinic rays. (In the formula, ArN2+ represents an aromatic diazonium group and represents an x-bs acid anion.) Specific examples of aromatic diazonium compounds that form salts include 4-diazo-1-methquine-5-nitro benzene,
4-Diazo-2-chlorobenzene, 4-Sifso 2.5
-dichlorobenzene, 4-diazo-1-nitro-5-methoxybenzene, 4-diazo-2-chloro-5-methoxybenzene, 4-diazo-1-chloro-5-methylbenzene, 4-diazo-2- Nitro-5-methylbenzene, 4-diazo-2,6-dydolifluoromethylbenzene, 4-thia7"-1-chloro-5-trifluoromethylbenzene, 4-thia7"-2-)+7fluoromethyl-5 -ethylsulfonylbenzene, 4-diazo-3-meth)xy-6-benzylsulfonylbenzene, 4--)azo-2-chloro-5-methylbenzene, 4-diazo-2
-diethylaminosulfonyl-5-methoxybenzene,
4-diazo-2-trifluoromethyl-5-chlorobenzene, 4,4-cyclo-2-diasocyphenyl ether, 4-chloro-2-diasocyphenyl ether,
Examples include 4-cyasycin, 5-10-rubenzoylaminobenzene, and the like. A specific example of the acid anion is BF2-
.

Examples include PF, -, C, H, (J3so3- (sulfosalcylic acid ion), but are not limited to these as long as they are poorly soluble or insolubilizing agents in water.

Used in the present invention, highly photosensitive and extremely thick absorption wavelength 350
A diazo compound that can react with 2,3-dihydroxynaphthalene to form a blue-colored azo dye is a yellow diazonium salt represented by the general formula AI'N2''X-. , is a compound that can be decomposed by actinic rays. (In the formula, ArN2+ represents an aromatic diazonium group, and X- represents an acid anion.) Specific examples of diazonium compounds that form salts include 4-diazo -1-dimethylaminobenzene, 4-diazo-1-diethylaminobenzene, 4-diazo-1-
Ethylhydroxyethylaminobenzene, 4-thia 7
"-1-ethylbenzylaminobenzene, 4-diazo-
1-anilinobenzene, 4-diazo-1-4'-methoxybenzoylamino-2゜5-jethoxybenzene, 4
-Sia7”-1-morpholinobenzene, 4-diazo-1
-morpholino-2,5-diinpropylbenzene, 4-
Diazo-1-morpholino-2,5-schif'toxybenzene, 4-diazo-1-morpholino-2,5-jethoxybenzene, 4-diazo-1-tolylmercapto-2゜5-jethoxybenzene, 4- Sifso 1-methoxyanilinobe/ase/, 4-diazo-1-pyrrolidino-2-methylbenzene, 4-diazo-1-pyrrolidino-2-methoxybenzene, and the like can be mentioned. A specific example of the acid anion is 13F7.

Examples include PF, -, CtHs03SO3- (sulfosalcylic acid ion), but the agent is not limited to these as long as it is a poorly soluble or insolubilizing agent in water.

The coupler other than 2,3-dihydroxynaphthalene used in the present invention is the aromatic diazo compound A used in the present invention.
Any compound that can react with the aromatic diazo compound B used in the present invention to form a blue azo dye may be used. I can do it. Specific examples of such couplers include 2-hydroxynaphthalene-3-carboylpropylamide, 2-hydroxynaphthalene-3-carboylanilide, 2-hydroxynaphthalene-3-carboyl-2'-methylanilide, 2-hydroxynaphthalene-3-carboylanilide, Hydroxynaphthalene
3-Carboyl-2'-ethoxyanilide, 2-hydroxynaphthalene-3-carboyl-3'-nitroanilide, 2-hydroxynaphthalene-2,'5'-dimethoxyanilide, 2-hydroxynaphthalene-2'-methyl-4 '-Chloranilide, 2-hydroxynaphthalene-
Carboyl-morpholinopropylamide, 2,3-xedroxynaphthalene-6-sulfamoyl, 2-hydroxyanthracene-3-carboyl-2'-metelani IJ)'', l-oxynaphthyl-4-phenylketone,
Examples include 2-hydroxynaphthalene-3-carboylmethyl ester, 2-hydroxynaphthalene-3-carboylphenyl ester, and the like.

Furthermore, as a coupler other than the above-mentioned couplers used in the present invention, it is possible to react with aromatic diazo compound A and aromatic diazo compound B used in the present invention to form an azo dye having a similar color tone. Compounds can also be used as couplers. Such couplers are used as tone modifiers. Specific examples thereof include 2.2'-4,4'-tetrahydroxydiphenylsulfide-quinolone-2. 2-L-acetylacetamido-6-nitoxypenzotheazole, 3.3
'-dimethyl 4.4'-acetylacetamidodiphenyl, acetylaceto-2.5-dimethoxy-4-chloranilide, 1-hydroxynaphthalene-2-carboylphenyl ester, resorcin, 6,6'-dimethyl-
3.3'-)rimeteredioxydiphenol, 1-phenyl-3-methyv-5-pyrazolone, 1 --yx
=tv-3-phenylacetamide and the like.

The thermal developer used in the present invention is a poorly water-soluble or water-insoluble compound, and a compound that creates a hot coupling atmosphere during heating is used.

Specifically, organic amines, guanidines, Iupipe J+
These include compounds, amidines, morpholines, bigianides, guanylureas and their salts.

Preferably, a salt of a polybasic acid having a first-order dissociation constant of 2×10 to IX10 and an alkyl-substituted guanidine represented by the general formula % is most suitable.

More specifically, examples of the alkyl-substituted guanidine include octylguanidine, nonylguanidine, decylguanidine, undecylguanidine, laurylguanidine,
Tridecylguanidine/, myristylguanidine, hexadecylguanidine, octadecylguanidine, icosylguanidine, tocosylguanidine, dioctylguanidine, dioctadecylguanidine, N-methyl-N-octadecylguanidine, N-methyl-N-decylguanidine/, N , N-didecylguanidine, and the like.

On the other hand, when forming a salt with an alkyl-substituted guanidine, the first-order dissociation constant 2X 10 -I X 10-'
Examples of polybasic acids include benzenesulfonic acid, trichloroacetic acid, Chellaic acid, glycerophosphoric acid, maleic acid,
Phosphoric acid, citric acid, malonic acid, tartaric acid, malic acid, lactic acid, etc. are suitable.

As the acid stabilizer used in the present invention, various known nonvolatile acids used for diazo type materials can be used. Examples include citric acid, gluco/acid, oxalic acid, tartaric acid, sulfamic acid, hydroxylamine hydrochloride, boric acid, phosphoric acid, and the like. In addition, thiourea, L-ascorbic acid,
Even if urea, allyl isothiocyanate, etc. are used, the color development sensitivity and storage stability of the recording medium of the present invention will not be impaired.

The polymer binder used in the present invention is used to improve the adhesion between the recording material and the support, the coating uniformity, or the water resistance. Even if it is not added, the characteristics of the recording medium of the present invention will not be impaired. Examples of polymer binders include polyvinyl alcohol, hydroxyethyl cellulose, polyvinyl alcohol, gum arabic, and polyvinyl acetate emulsion.

Methyl cellulose, ethyl cellulose, holvinyl petyral, polyvinyl acetate, polystyrene, nitrocellulose, cellulose acetate butyrate polymer,
Examples include salt and vinegar picopolymers and polymethacrylic acid esters.

Next, a known coating method can be used to coat the recording layer on the support. Specifically, a coating liquid in which a recording layer forming composition consisting of a diazo compound, a coupler, an acid stabilizer, a polymeric binder, etc. is dissolved in water or an organic solvent, or uniformly dispersed in a disperser is prepared. A two-color thermosensitive recording material can be produced by applying the composition onto a support such as paper, glass, film, or sheet using a coating machine and drying it at a low temperature. It is also possible to laminate various combinations of recording layer forming compositions. Furthermore, it is also possible to provide a protective layer on the recording layer.

The mechanism is simple because two-color images are formed repeatedly, and maintenance is free because there are no consumables. Furthermore, since the formed image is fixed, a stable permanent image can be provided. Therefore, various applications are possible.

For example, it is used in a wide range of application fields, such as color information recording media for facsimiles, printers, electronic blackboards, etc., recording media for highlighting certain types of information, and recording media for tickets, cards, and sticker-less commuter passes that require counterfeit prevention. can.

Examples Examples of the present invention will be shown below. In each example, "part" means part by weight.

<Example J> (1) Preparation of diazo compound dispersion (2) The above composition was pulverized and dispersed in a sand mill for 2 hours to obtain a uniform dispersion having an average particle size of 1 μm.

■Preparation of coupler and thermal developer dispersion■The above composition was pulverized and dispersed in a ball mill for 24 hours, and the average particle size was 2.5μ.
A dispersion was obtained.

■Composition of recording layer coating liquid The dry weight of the coating liquid consisting of the above composition is 7g/m2.
The mixture was precoated with PVA and then applied onto a high-quality paper, and dried at a low temperature to obtain a two-color thermosensitive recording paper.

<Example 2> 2-Hydroxynaphthalene-3 in dispersion ■ of Example
A two-color thermal paper was prepared in the same manner as in Example 1 except that -carboy/I/-2'-methoxyanilide was replaced with 2-hydroxyanthrace/-3-carboyl-2'-methylanilide.

<Example 3> A two-color thermosensitive recording paper was prepared in the same manner as in Example 1, except that the aromatic diazo compound A in the dispersion (1) of Example was changed.

<Recording method of Examples 1 to 3> The two-color recording paper obtained in Examples 1 to 3 was coated with Toshiba's Marcie Emulator (printing conditions, applied voltage 14 V).
, l ms-0N10FF), and the first
I got a colored image. Next is Ricopino Istart type 4 (manufactured by Ricoh)? : was used to expose the entire surface to light, and the diazo compound on the longer wavelength side was decomposed.

Thereafter, a first colored image was obtained on the unprinted recording surface using a Toshiba thermal simulator. A second colored image was obtained by thermal printing under the same conditions. The pale color thus obtained was captured using a Macbeth reflection densitometer to measure the clear two-color images with different tones. The results are shown in Table 1.

Furthermore, after recording, the problem of conventional leuco-based thermal paper, such as erasing when it comes into contact with cellophane tape, erasers, PVC sheets, etc., or discoloration due to ink from diazo copying paper or felt-tip pens, did not occur. In this way, it was possible to provide a two-color heat-sensitive layer with excellent storage stability after recording.

<Example 4> ■Coating liquid for diazo compound■ ■Coating liquid for coupler and thermal developer■ The above composition was dispersed in a sand mill for 2 hours to obtain an average particle size of 2.
．． A uniform dispersion of 5μ was obtained.

A coating solution (1) of a diazo compound having the above composition was coated on a 20θμ white polyester sheet as a dry weight of 19/d.
- Apply with a wire bar and apply at low temperature (70℃).
(below). Coating liquid ■ consisting of a coupler and a heat developer, which have been uniformly dispersed in advance, is applied onto the layer using a wire bar to a dry weight of 5 gim, and dried at a low temperature (70°C or less). A two-color thermosensitive sheet was produced.

This recording sheet was printed using a Toshiba thermal head (printing conditions: applied voltage: 12V, pulse width: 2.5 ms, 0N10FF).
A black image was obtained by printing. Next, a chemical lamp (λ
max == 42ofim) and 30 r on the entire surface.
rJ, ort tD: r-Nelky was irradiated. Thereafter, printing was performed on the unrecorded recording surface using a Toshiba thermal head under the same conditions as above to obtain a red image. Finally, when the entire surface was irradiated with energy of 50 mJ4' using a high-pressure mercury lamp and fixed, two-color images were obtained: a black image with an optical density of 1.0 and a red image with an optical density of 0.8 against a pale color background. . Furthermore, when a hot plate at 120° C. was applied to the gold surface after recording, no recoloring occurred due to heat. In addition, there was no change in color or fading due to adhesion of solvents such as water or alcohol, or decoloration due to plasticizer in cellophane tape.

In this way, it was possible to provide a two-color thermosensitive recording sheet with excellent tamper-proofing effect and excellent storage stability after recording.

[Brief explanation of drawings]

FIG. 7 shows explanatory diagrams of 4-diazo-3-methoxynitrobenzene (aromatic diazo compound A), a 4-diazo-invention two-color thermosensitive recording material, and a recording method thereof, respectively. 1...Recording layer 2...Support 3...
・Coupler 4...Aromatic diazo compound A5...Aromatic diazo compound B 6...Blue-based azo dye 7...Red-based azo dye

Claims (1)

[Claims] (1) Diazo compound, coupler, acid stabilizer on the support,
In a recording medium provided with a recording layer containing a thermal developer, a polymeric binder, etc., the diazo compound is colorless or pale yellow, has a maximum absorption wavelength of less than 350 mm, and contains at least 2,3-dihydroxynaphthalene. An aromatic diazo compound that can undergo a coupling reaction to form a red-based azo dye, and a yellow color with a maximum absorption wavelength of 350 mm or more, and a coupling reaction with at least 2,3-dihydroxynaphthalene to form a blue-based azo dye. 1. A two-color thermosensitive recording material comprising at least an aromatic diazo compound.