JPS5945190A - Black color forming thermodeveloped diazo type recording body - Google Patents

Abstract

PURPOSE:To obtain a black color forming thermodeveloped diazo type recording material with a preservation stability free from variation in the hue of dye due to changes in heat energy by combining specified alpha and beta naphthol derivatives properly. CONSTITUTION:A recording layer which has a diazonium fluoroborate, yellow and blue coupling agent made of alpha and beta naphthol derivatives, a salt of alkyl substituted guanidine as acid stabilizer and thermodeveloper as basic recording structure elements is provided on a support. Then, the blue coupling agent shall be as given by the formulas I and II. The thermodeveloper shall be polybasic acid with the primary dissociation constant of 2X10<-1>-1X10<-4> and a compound of the formula III. The black color forming thermodeveloped diazo type recording body thus obtained has a preservation stability, a thermal color formation sensitivity, a chemical resistance and a black color formability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-developable diazo-type recording material that can be processed without any processing, and particularly relates to a heat-developable diazo-type recording material that is black-forming.

Conventionally, there are many known image recording methods for converting information into visible images. In general.

It causes physical or chemical changes in response to energy such as light, radiation, electrolysis, magnetism, heat, pressure, etc.

For example, there are two types of recording methods that use heat: one that forms images using physical changes such as melting, sublimation, and volatilization, and one that forms images that utilizes color development due to chemical changes caused by heat. . However, since such a heat-sensitive recording material has a structure in which the recording layer is obtained by heat, the non-image area also has the ability to develop color when heat is applied later. For that reason,
It has a defect due to the structure of the thermal recording medium in that if it is mistakenly brought close to a heat source, it will develop color and lose its ability as a recording medium. Therefore, improvements in this respect are desired in the general market.

Therefore, in recent years, a heat-developable diazo type recording material, which is a dry imaging system, has attracted attention as a heat-sensitive recording material, and development is progressing toward practical use.

Here, thermal diazo recording materials can be roughly classified into three types: alkali precursor type, coupler precursor type, and diazo precursor type. The image forming method is phenomenologically the same. First, the diazo compound and the coupler undergo a coupling reaction using fm energy to form an image using an azo dye. Next, the entire surface is irradiated with light energy to remove the unimaged areas. It loses its color-forming ability and fixes to form a permanent image.The difference between the three types of image formation methods is the method of inducing the coupling reaction.For details, the alkali precursor type The thermal phenomenon agent trapped in thermal energy causes chemical changes such as decomposition, dissociation, and melting.
In this method, the recording layer is placed in an alkaline atmosphere, a diazo compound and a coupler cause a coupling reaction, and an image formed by an azo dye is formed. The coupler precursor type is a method in which a hornopler, which is inactive in coupling reactions at normal temperatures, is activated by thermal energy and causes a coupling reaction with a diazo compound to form an azo dye image. The diazo precursor type is a method that utilizes the optical structural isomerization reaction of diazosulfonate. The anti-type diazosulfonate, which is inactive for coupling reactions, isomerized to the active syn-type by light energy, and is coupled with camplar by thermal energy. cause a reaction,
This is a method of forming an azo dye π-waggling image.

Heat-developable diazo type recording materials using the above three types are already known, and numerous patents have been issued. For example, as an alkali precursor type, US Pat.
Heat-developable diazo type recording materials using various color development aids are described in Japanese Patent Publication No. 248, Japanese Patent Publication No. 49-3926, and the like.

As a coupler precursor type, Tokuko Sho 45-4015
Publication No. 3, Special Publication No. 47-11797, Special Publication No. 11797
No. 1,562 and Japanese Patent Publication No. 14,522/1980 describe heat-transformable (8) diazo type recording materials using a 2,3-dihydroxybenzoic acid derivative as a coupler which is activated for coupling by one thermal energy. And, as a diazo precursor type, US Patent No. 2217189, British Patent No. 544702, German Patent No. 734
No. 302 and Japanese Unexamined Patent Publication No. 56-5790 describe a recording medium comprising a diazosulfonate compound, a coupling agent, and a kudzu molecule binder, and a recording method thereof.

However, these conventional heat-developable diazo recording materials,
Alkaline precursor type 5F has heat-sensitive coloring sensitivity but lacks storage stability, while coupler precursor and diazonium precursor types have storage stability but do not provide coloring sensitivity that is compatible with the mechanism. The disadvantage of being ugly? I had it. For this reason, various improvements are being made and development is underway to put it into practical use, but a practical heat-developable diazo recording material that has both heat-sensitive coloring sensitivity and storage stability has not yet been completed. is the current situation.

The present inventors conducted additional experiments on the conventional heat-developable diazo type recording material, and as a result, it was found that the height of the heat-sensitive coloring sensitivity is caused by the recording material. f tx That is, the heat-sensitive coloring sensitivity of the coupler precursor type and the diazonium precursor type is due to the heat-sensitivity of the coupler and diazosulfonate, respectively. The thermal sensitivity of these organic compounds is determined by the position or type of substituents. However, even if a substituent that improves thermal sensitivity is added, some improvement is seen, but is this a drawback due to the structure of the recording material that the thermal sensitivity intended by the inventors of wood cannot be obtained? Because we have
The above two types were unsuitable for practical use.

Therefore, the inventors focused on the characteristics of the pre-alkali, frame type, that is, the high heat-sensitive coloring sensitivity, and developed the following regarding the heat developer that determines the heat-sensitive coloring sensitivity of this type.
Synthesize many substances and each synthetic substance? As a result of investigating the heat-sensitive color development sensitivity and storage stability of heat-developable diazo-type recording material used as a heat developer, it was found that certain salts of guanidine compounds were ignored. The inventors discovered that the method had excellent properties in terms of color development and heat-sensitive coloring sensitivity, and filed an application as Japanese Patent Application No. 57-011243.

The inventors further researched a black diazo-type recording medium by combining the camping agents of different hues that are normally used in the diazo photosensitive paper used in the above patent application. It was possible to obtain a black color by combining a compound with an active methylene group such as an acetamide derivative and a β-naphthol derivative as a blue horn blistering agent, but the compound with an active methylene group was Horn 7'
Due to its fast pulling speed, it has storage stability and thermal coloring sensitivity that are suitable for practical use based on compounds with active methylene groups. This method has the drawback that the hue of the image changes and it is not possible to form a black image depending on the thermal coloring conditions.

As a result of intensive research to compensate for the above-mentioned drawbacks, the inventors of the tree discovered that by using a combination of certain α and β-naphthol derivatives, the dye had good storage stability and its hue did not change due to changes in thermal energy. A black color-forming heat-developable diazo type recording material was discovered, and the present invention? I was able to achieve this.

That is, the present invention provides diazonium borofluoride, α
and a recording layer consisting of a yellow and blue coupling agent consisting of a β-naphthol derivative, an acid stabilizer, and a salt of an alkyl-substituted guanidine as a thermal mass imaging agent as basic recording constituents. Silence [It is an elephant diazo type recording body. More specifically, in a recording medium in which a recording layer containing diazonium borofluoride, blue and yellow coupling agents, an acid stabilizer, and a thermal developer as main components is provided on a support, the blue cambling agent has the general formula +1). (However, X represents -0Ar or -NH-Ar, and Ar represents a phenyl derivative.) The yellow cambling agent is (however, -0
Ar' or -NH-Ar', and Ar
' indicates a phenyl derivative. ), and the thermal developer has a first-order dissociation constant of 2-X10-' to lX10
-' polybasic acid and general formula (III) 9- R, -N-C-NH2 1] NH (However, at least one of R7 and R2 is C8-
The C24 alkyl group is a hydrogen atom or an alkyl group of 01 or more. ) It is a black color-forming heat-developable diazo type recording material.

The thermal phenomenon diazo type recording material of the present invention is an alkali precursor type, and as a thermal mass f-effect agent, the -order dissociation constant is 2.
Polybasic acid of X10-' to lX10-' indicates an inorganic or organic acid with a base acid or higher. ) and general formula % formula % (However, at least one of RI and R2 is C8-C
24 alkyl groups, and the others are hydrogen atoms or 01 or more alkyl groups. ) is characterized by using a salt with an alkyl-substituted guanidine.

Furthermore, even if the present invention is silent [elephant diazo type recording material = 10]
- The coupling agent is represented by the general formula (1) as a monochrome force-knobbling agent, and Ar represents a phenyl derivative. ), and the yellow coupling agent is (provided, or -0
Ar', or -NH-Ar', and A
r' represents a phenyl derivative. ) is characterized by using the compound shown in

The heat-developable diazo recording material of the present invention has a diazonium salt, a heat developer, and a blue and yellow coupler as a coupling agent, which exhibit a property of being poorly soluble in water, as is clear from the above structural formula. Because of this, the pre-coupling phenomenon due to temperature and humidity is suppressed, resulting in extremely high storage stability. Furthermore, since the coupling speeds of the blue and yellow couplers, which are coupling components, are approximately the same, the amount of acid stabilizer added to the recording layer, which prevents pre-coupling, should be based on the faster coupler (if necessary). Therefore, both peaks that are thermally colored exhibit a black color under any thermal coloring conditions.

Here, the recording material used in the present invention will be described in detail. First, the coupling agent used in the present invention has the general formula (1) as a blue coupling agent (where X is 10Ar, or -
Indicates NH-Ar, and Ar indicates a phenyl derivative. ), specifically, 2-hydroxynaphthalene-ro-carbonylphenyl ester, 2-hydroxynaphthalene-6-carbonyl-4'-
Methoxyphenyl ester, 2-hydroxynaphthalene-6-carbonyl-3'-nitrophenyl ester, 2
-Hydroxynaphthalene-3-carbonyl-4'-chlorophenyl ester, 2-hydroxynaphthalene-3-
Carbonyl-2'-#-f phenyl ester, 2-hydroxynaphthalene-6-carbonyl-27-nitoxyphenyl ester, 2-hydroxynaphthalene-3-carbonyl-2'-methoxyphenyl ester, 2-hydroxynaphthalene-6 -carbonyl-2'-methyl-4
'-Chlorphenyl ester, 2-hydroxynaphthalene-3-carbonyl-2'-methoxy-5'-nitrophenyl ester, 2-hydroxynaphthalene-3-carbonyl-27-methyl-5' chlorphenyl ester,
2-hydroxynaphthalene-3-carbonyl-2'-methoxy5' chlorophenyl ester, 2-hydroxynaphthalene-3-carbonyl-6', 6'-dimethoxy-4-chlorophenyl ester, 2-hydroxynaphthalene-3- Carbonyl-3'-chloro-4', 6'-dimethoxyphenyl ester, 2-hydroxynaphthalene-6-carbonyl-4'-methoxyanilide, 2-hydroxynaphthalene-3-carbonyl-3'-nitroanilide, 13-2 -Hydroxynaphthalene-6-carbonyl-47-chloroanilide, 2-hydroxynaphthalene-6-carbonyl-2'-methylanilide, 2-hydroxynaphthalene-6-carbonyl-2'-ethoxyanilide, 2-hydroxynaphthalene-6- Carbonyl-27-methoxyanilide, 2-hydroxynaphthalene-3-carbonyl-2'-methoxy-5'-nitroanilide, 2-hydroxynaphthalene-3-1 fluoronyl-2'-methyl-4
'-Chloranilide, 2-hydroxynaphthalene-3-
carbonyl-27-medoxy-47-chloranilide,
2-hydroxynaphthalene-6-carbonyl-3',6
'-Dimethoxy-4'-chloroanilide, 2-hydroxynaphthalene-3-carbonyl-3'-chloro-4',
6'-dimethoxyanilide, etc.

(However, it represents -0Ar', or -NH-Ar1, and Ar' represents a phenyl derivative.), specifically 1-hydroxynaphthalene-
2-carbonyl-phenyl ester, 1-hydroxynaphthalene-2-carbonyl-4'-methoxyphenyl ester, 1-hydroxynaphthalene-2-carbonyl-
3'-nitrophenyl ester, 1-hydroxynaphthalene-2-carbonyl-47-chlorophenyl ester, 1-hydroxynaphthalene-2-carbonyl-2'-
Methyl phenyl ester, 1-hydroxynaphthalene
2-carbonyl-27-nitoxyphenyl ester, 1
-Hydroxynaphthalene-2-carbonyl-27-methoxyphenyl ester, 1-hydroxynaphthalene-2
-Carbonyl-2'-methyl-4'-chlorophenyl ester, 1-hydroxynaphthalene-2-carbonyl-
2'-methoxy-5'-nitrophenyl ester, 1-
Hydroxynaphthalene-2-carbonyl-27-methyl-57-chlorophenyl ester, 1-hydroxynaphthalene-2-carbonyl-2'-methoxy-57-chlorophenyl ester, 1-hydroxynaphthalene-2-carbonyl-3', 6' -dimethoxy-4-chlorophenyl ester, 1-hydroxynaphthalene-2-carbonyl-37-chloro-4',6'-dimethoxyphenyl ester, 1-hydroxynaphthalene-2-carbonyl-
47-Medoxyanilide, 1-hydroxynaphthalene-
2-carbonyl-6-nitroanilide, 1-hydroxynaphthalene-2-carbonyl-4'-chloroanilide, 1-hydroxynaphthalene-2-carbonyl-2'-
)-f-ruanilito, 2-hydroxynaphthalene-2-
Carbonyl-2'-ethoxyanilide, 1-hydroxynaphthalene-2-carbonyl-27-medoxyanilide, 1-hydroxynaphthalene-2-carbonyl-2'-
Methoxy-5'-nitroanilide, 1-hydroxynaphthalene-2-carbonyl-2'-#thiru4'-chlor7 = IJ, 1-hydroxynaphthalene-2
-carbonyl-2'-methoxy-47-chloroanilide, 1-hydroxynaphthalene-2-carbonyl-3',
6'-dimethoxy-4'-chloranilide, 1-hydroxynaphthalene-2-carbonyl-6fuchlor=4'
, 6'-dimethoxyanilide, etc.

The recording materials other than the coupling agent used in the present invention will be described in detail below.

Various known diazo compounds can be used as the diazo compound used in the present invention. For example, paraphenylenediacine N-N-substituted compounds (4-diazo-N-diethylaniline etc.), aminohydroquinone ethers (4-
Diazo-2-5-dibutoxy-N-N-diethylaniline-4-diazo-2-chloro-5methoxy-N-benzoylaniline etc) = aminodiphenyl-aminodiphenylamine and similar compounds (4-diazo-2-5-
4'-trisidiphenylamine etc.), heterocyclic amine derivatives (4-diazo-2-5-Sif")xy-N-phenylmorpholine etc.). The diazo compounds mentioned above are Used as an organic solvent-soluble salt such as diazonium borofluoride.

Next, as a hydrophobic thermal developer, the -order dissociation constant is 2
10-' to I
A salt with an alkyl-substituted guanidine can be used.

The solubility of such alkyl-substituted guanidine salts in water is extremely low, and is on the order of several square meters or less per 100 ml of aqueous solution. That is, guanidine compounds have more hydrophobic properties than hydrophilic properties. As an acid that can form an appropriate salt with an alkyl-substituted guanidine exhibiting hydrophobicity, the first-order dissociation constant is 2X10-'~l.
A polybasic acid of X10-' can be chosen.

More specifically, the alkyl-substituted guanidine includes, for example, octylguanidine, nonylguanidine, decylguanidine, undecylguanidine, 18-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, polybasic acids with a first-order dissociation constant of 2X10-' to 1X10-' that can form salts with alkyl-substituted guanidines include benzenesulfonic acid, trichloroacetic acid, oxalic acid, glycerophosphoric acid, maleic acid, phosphoric acid,
Citric acid, malonic acid, tartaric acid, malic acid, lactic acid, etc. are suitable.

Furthermore, the alkyl-substituted guanidine salt used in the present invention can be synthesized by a known method.

That is, a solution of alkyl-substituted guanidine dissolved in a suitable solvent is heated at 50°Cvc, and while stirring, a stoichiometric amount is weighed in advance, and the dissolved solution is added dropwise. By continuing to stir for about 10 minutes after the completion of dropping, approximately 100%
can be produced with a yield of

Next, the acid stabilizer used in the present invention can be any of the various known nonvolatile acids used in diazo type materials. For example, citric acid, gluconic acid, oxalic acid, tartaric acid,
These include sulfamic acid, hydroxylamine hydrochloride, boric acid, and phosphoric acid. Furthermore, in order to improve the storage stability of the recording medium after recording, thiourea, L-ascorbic acid, urea, allyl isothiocyanate, etc. may be used as antioxidants to improve the color development sensitivity and storage stability of the recording medium of the present invention. It won't hurt.

Further, even if a thermoplastic resin is used as a polymeric binder to improve the storage stability and chemical resistance of the recording medium of the present invention, the characteristics of the recording medium of the present invention will not be impaired. Such thermoplastic resins include, for example, polystyrene, polymethylstyrene, polyphenylstyrene, polychlorostyrene, polyxylene, polyvinyl butyral, cellulose acetate butyrate copolymer, polyethylene terephthalate, triacetylcellulose, polyacrylate, polyacrylonitrile, polymethyl These include methacrylate, polymethyl/butyl acrylate, inbutyl methacrylate, butyl methacrylate, polychloromethyl acrylate, polyvinyl tert-butyl ether, polyvinyl chloride, salt and vinegar picopolymer, and the like.

Next, a known method can be used to coat the recording layer on the support in the present invention.

Specifically, a dispersion containing a liquid in which a recording agent consisting of a diazo compound, a coupling agent, an acid stabilizer, an antioxidant, and a polymeric binder is dissolved in an organic solvent, and a heat developer prepared in advance. A heat-developable diazo type recording medium can be produced by applying a coating liquid obtained by uniformly mixing the liquids onto a support such as paper, glass, or film using a wire bar or the like, and drying at a low temperature. In addition, when the recording layer has a two-layer structure, a coating liquid in which a thermal developer and a polymeric binder are uniformly dispersed in an organic solvent is applied onto the support using a wire bar, etc., and after drying. , a diazo compound, a camping agent on the layer,
A heat-developable diazo-type recording material is manufactured by applying a solution of a recording agent consisting of an acid stabilizer, a polymeric binder, and, if necessary, an antioxidant dissolved in an organic solvent using a wire bar and drying it. I can do it.

The method for recording the heat-developable diazo recording material thus obtained is as follows:
An image is formed on the recording layer of the recording medium using thermal energy, and then the entire surface is irradiated with light energy to fix it.Using the heat and light energy, an image is formed on the permanent side [or an image is formed on the recording medium]. A method of forming a permanent image using light and thermal energy is possible, in which a transparent original is placed in close contact with the layer, a latent image is formed by applying light energy, and then thermal energy is applied to the entire surface to develop it. . However, as the energy source used here, a thermal head, a thermal oven, an infrared ray, a laser beam, a thermal roll, etc. can be used as a thermal energy source. Furthermore, a mercury lamp, a xenon lamp, a tungsten lamp, a xenon flash, a laser, etc. can be used as a light source that generates optical energy.

Since the present invention has the above configuration, it has various effects as shown below. That is, 1) The coupling product of the diazonium compound and the coupler forms a black azo dye, and there is no change in hue due to a change in thermal energy.

2) The diazonium compound, coupler, and thermal developer exhibit hydrophobic properties, and the thermal developer is thermally stable at temperatures below 100°C, so precoupling occurs due to temperature and humidity during storage. be suppressed.

3) Since the diazonium compound and the coupler are hydrophobic, the black azo dye that is the reaction product of them has excellent water resistance and chemical resistance.

As described above, the black color-forming heat-developable diazo type recording medium of the present invention has satisfactory storage stability, heat-sensitive coloring sensitivity, and chemical resistance, all of which were key to its practical application. Certain high-level applications are possible. For example, it is a particularly effective recording medium for computer output printers, data communication terminals, and for tickets, cards, and sticker-less commuter passes that require counterfeit prevention.

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

Example 1) A dispersion consisting of part of n-decylguanidine tartrate, 50 parts of methyl ethyl ketone, and 50 parts of toluene was uniformly dispersed using a disperser. 06 parts of oxalic acid in the dispersion, P-N
= 1 part of N-diethylaminobenzeneazonium borofluoride, 2-hydroxynaphthalene-3-carbonyl-4'-
0.6 parts of methoxyphenyl ester, 1-hydroxynaphthalene-2-carbonylphenyl ester t4mw
A photosensitive solution was prepared by adding and dissolving. The photosensitive solution was applied onto water- and oil-proof paper using an air knife coater and dried to produce a black color-forming heat-developable diazo recording paper. Place the recording paper (on a heating plate [25 x 10% x 10 pieces]) for 50 to 200 minutes in advance.
Under the same conditions (pressure: 2 to 7/d, time: 2 sec) using a thermal gradient tester set with a temperature gradient in the range of C.
), and then the entire surface was irradiated with a mercury lamp to fix it, and the hue and color density at each temperature were measured. When measuring the color density, a Macbeth densitometer was used to measure the optical density without a filter or through a red filter as a smear color or as an eye color. The color development sensitivity curve is shown in FIG. As is clear from the results shown in FIG. 1, the optical density at each temperature was higher under the condition without a filter, and a black image could be formed with no change in the hue of the dye image depending on the heating temperature.

Example 2) 5 parts of myristylguanidine oxalate, 20 parts of polystyrene
A dispersion liquid consisting of 1 part, 70 parts of methyl ethyl ketone, and 30 parts of toluene was uniformly dispersed in a disperser. In the dispersion, 06 parts of citric acid, 0.2 parts of thiourea, 0.1 part of P-toluenesulfonic acid, 4 (-P-tolylmercap) -)
-2,5-jethoxybenzenediazonium borofluoride 1
part, 2-hydroxynaphthalene-ro-carponyl/-
1 part methylanilide, 1-hydroxynaphthalene-2-
One part of carbonyl-47-chloroanilide was added and dissolved to prepare a coating liquid. The coating solution was applied onto a diazo photosensitive paper base paper using a gravure coater and dried at 60°C to produce a black color-forming heat-developable diazo type recording paper.

A transparent original was placed in close contact with the recording paper and exposed to light using a Ricoh diazo copying machine to form a latent image.The entire surface was heated with a heat roll at 130°C to create a pale colored background. A black copy with an optical density of 12 was obtained. Further, even when heat was applied to the uncolored portions, no black portions were formed and fixing was not performed. Also, keep the recording paper at 40°C.
1 relative humidity 20, 10 days or 40°C 1 relative humidity 9
After leaving it at 0% for 2 days, a latent (8) was formed with light energy and developed with heat energy in the same manner as above, and a black image with an optical density of 12 was obtained, and no fogging of the base was observed. There wasn't.

After fixing, even if the image area was rubbed with gauze soaked in water, the image did not change color or fade. In this way, it was possible to provide a black coloring recording paper with excellent thermal coloring sensitivity and storage stability.

Example 3) 5 parts of octadecylguanidine citrate, 15 parts of polymethyl methacrylate, 70 parts of methyl ethyl ketone,
A coating solution containing 60 parts of toluene was uniformly dispersed in a dispersion machine.Polyester film (thickness: 200μ)
It was applied and dried using a roll coater in the upper part. On the layer, 6 parts of polymethyl meta7
- Morpholinobenzenediazonium borofluoride 12 parts, 2
A photosensitive solution consisting of 06 parts of -hydroxy-3-carbonyl-coumethoxyphenyl ester, 08 parts of 1-hydroxy-2-carbonyl-coumethoxy-47-chloroanilide, 50 parts of methyl ethyl ketone, and 50 parts of toluene was applied using a roll coater, The mixture was dried at 6 parts Celsius to produce a black color-forming heat-developable diazo type recording film.

This recording film was first printed using a Toshiba ■ thermal printer (printing conditions: 045 W, pulse width: 2 ms), and then the entire surface was exposed using a xenon flash (exposure energy: 450 J), resulting in a black image with an optical density of 11 against a pale color background. was formed. In addition, after printing with a thermal printer, the entire surface was not exposed to light using xenon flood, and the temperature was 30°C.
After leaving it for 4 months at 20% relative humidity and 1 month at 30℃ and 90% relative humidity, the entire surface was exposed with a xenon flash to check for discoloration, fading, and fogging of the base. No fog was observed. After fixing, even if the image was rubbed with gauze soaked in water, an aqueous solution of neutral detergent, petroleum ether, or alcohol, no discoloration or fading of the image was observed.

As described above, it was possible to provide a recording film with excellent black color development and properties that can withstand practical use.

[Brief explanation of the drawing]

FIG. 1 shows a heat-sensitive color development sensitivity curve of the black color-forming heat-developable diazo type recording paper of Example 1 of the present invention. In the figure, ■ is a thermal coloring sensitivity curve plotting the coloring density at each temperature measured by using the Macbeth densitometer (without a filter) using the recording paper, and ) shows a thermosensitive coloring curve in which the coloring density at each temperature measured by the method is plotted. Patent applicant Toppan Printing Co., Ltd. Representative Kazuo Suzuki 29- Figure 1

Claims (1)

[Claims] (1) In a recording medium in which a recording layer containing diazonium borofluoride, blue and yellow coupling agents, an acid stabilizer, and a thermal developer as main components is provided on a support, the blue cambling agent has the general formula (1). % formula % is shown, and Ar represents a phenyl derivative. ), and the yellow coupling agent is represented by the general formula T
I) It is a compound represented by ○ (or -0Ar' or -NH-Ar', and Ar' indicates a phenyl derivative), and the thermal developer has a constant number of primary dissociation. A polybasic acid of 2X10-' to I
The C24 alkyl group is a hydrogen atom or an alkyl group of 01 or more. ) A black color-forming heat-developable diazo type recording material, characterized in that it is a compound represented by: