JPS63242679A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material having high color forming sensitivity, generating no fog due to pre-coupling under a practical temp. and humidity condition and excellent in storage stability, by providing a recording layer, which contains a diazo compound, a thermal developer, an acid, a polymer binder and specific carbamic ester capable of becoming a coupler showing coupling activity at the time of heating, on a support. CONSTITUTION:A thermal recording material is formed by providing a recording layer, which contains a diazo compound, a thermal developer, an acid, a polymer binder and carbamic ester respresented by formula 1 (wherein Ar and Ar' are a substituted or non-substituted aromatic hydrocarbon group) capable of becoming a coupler showing coupling activity at the time of heating, on a support. As the diazo compound, a compound capable of being decomposed by active rays is effective. As the thermal developer, a hardly water-soluble or water-insoluble compound forming a coupling active atmosphere at the time of heating is used. The acid is used as an acid catalyst or acid stabilizer chemically changing the coupler at the time of heating to form a coupling active aromatic hydroxy compound. The polymer binder adheres the recording layer and the support and imparts the mechanical strength, water resistance and solvent resistance to the recording material.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a thermal recording medium, and in particular, thermal printing,
The present invention relates to a diazo thermosensitive recording material that can be photofixed to form a permanent image. More specifically, the present invention relates to a heat-sensitive recording material that has excellent storage stability, high color development sensitivity, and can be arbitrarily imparted with durability after recording.

(Conventional technology and problems) The hot recording method has a simple mechanism, is a dry method, and...

Because it has advantages such as being maintenance-free, it is widely used in facsimile and various printer fields.

In this process, leuco dye-based thermal paper is widely used. However, the recorded image cannot be fixed. If it comes into contact with heat or organic solvents after recording, it will recolor or fade. Therefore, its field of use was limited to temporary information transmission and recording. As a method to compensate for this drawback, there is a method using a diazo type thermosensitive recording material which can form a permanent image by thermal printing and photofixing, and various methods have been disclosed. A diazo type thermosensitive recording material is a recording material in which a recording layer consisting of a diazo compound, a coupler, and a thermal developer is provided on a support, and its storage stability and color development sensitivity are influenced by the characteristics of the thermal developer. If the thermal developer is water-soluble, precoupling of the recording medium will gradually progress during storage due to humidity, resulting in undesirable fogging. Therefore,
As a way to compensate for this drawback,
As disclosed in the above publication, an attempt has been made to improve storage stability by treating all recording materials to make them water-insolubilized and, in particular, using an insoluble guanidine compound as a heat developer. But with this method.

This is because the recording layer has a two-layer structure when manufacturing a recording medium.

Color sensitivity is sacrificed. Even if an attempt was made to increase the color development sensitivity by using a single recording layer, the guanidine compound used as a thermal developer is alkaline.

It also has the disadvantage that pre-coupling occurs in the coating liquid (even if it is a dispersion type), resulting in color development.

In addition, as disclosed in JP-A-59-190886 as having storage stability and color development sensitivity,
There is a method in which one of the diazo compound, coupler, and thermal developer is contained in a microcapsule, or two types are contained in the same or open microcapsule. However, since microcapsules are used, 1. In manufacturing recording media, it is necessary to use a water-dispersed coating liquid. Therefore, the obtained recording medium has good water resistance and mechanical strength (friction resistance).

(scratch resistance, etc.). This is particularly noticeable when a plastic sheet is used as the support. Therefore, it has the disadvantage that it cannot be used for applications that require durability after recording.

(Objectives of the Invention) The present invention was developed in view of the above circumstances, and the first object is to provide a high color development sensitivity and no fogging due to pre-coupling under practical temperature and humidity conditions. An object of the present invention is to provide a heat-sensitive recording medium having excellent storage stability. The second object of the present invention is.

It is an object of the present invention to provide a heat-sensitive recording material with excellent manufacturing suitability, which allows a single recording layer to be obtained whether the coating liquid is aqueous or solvent-based.

(Summary of the Invention) To achieve the above object, the heat-sensitive recording material of the present invention contains on a support a diazo compound, a thermal developer, an acid, a polymeric binder, and the following general couplers that can become coupling active upon heating. Carba I Ar -QC-NH-Ar' represented by the formula (Ar and Ar' represent substituted or unsubstituted aromatic hydrocarbon groups) (Detailed explanation of the thermal recording material which is a detailed explanation of the invention) do.

Carbamate ester compounds are very stable compounds at room temperature, but are known to dissociate into hydroxy compounds and incyanate compounds when exposed to temperatures of 100° C. or higher. This reaction is applied to create an aromatic human coupler with coupling activity.

The carbamate ester derivative obtained by the reaction of a hydroxy compound and an incyanate compound converts into a coupling-active compound (aromatic hydroxy compound) when heated in a system consisting of the compound, a diazo compound, an acid stabilizer, and a thermal developer. The present invention was achieved by discovering that azo dyes can be formed by reacting with diazo compounds.

The following is a diazo compound on a support according to the present invention.

A heat-sensitive recording material characterized by being provided with a recording layer comprising a heat developer, an acid, a polymeric binder, and a carbamate ester represented by the following general formula that can become a coupling-active coupler when heated. 0 Ar-QC-NH7Ar'(A' and Ar' represent a substituted or unsubstituted aromatic hydrocarbon group) will be explained in detail using a specific example.

2,5-dibutoxy-4-morpholinobenzenediazonium salt (compound 1) as a diazo compound.

Image formation on a recording body consisting of a recording layer containing 3-carboanilidenaphthalene-2-phenylcarbamate (Compound 2) as a compound that can become a coupling-active compound when heated, and octaguanidine tartrate (Compound 5) as a thermal developer. The reaction is represented by the following formula, Scheme 1 (Compound 2) (Compound 4)
(Compound 5) Scheme 2 (Compound 1) (Compound 7) 1) In Scheme 1, when the recording layer is heated on a hot plate at 120°C, Compound 2 undergoes the dissociation reaction of Scheme 1,
2-Hydroxynaphthalene-3-carboylanilide (
Compound 4) and phenyl isocyanate (Compound 5).

2) In Scheme 2, Compound 4 undergoes a coupling reaction with Compound 1 in the presence of Compound 3.

Forms a color-growing azo dye (compound 6).

3) In Scheme 3, Compound 1 becomes a colorless cured compound (Compound 7) by irradiating the entire surface of the hot stamp with active light such as from a high-pressure mercury lamp.

In the heat-sensitive recording material of the present invention, the above 1)-2)-3)
The image forming step forms a permanent image. In these reactions, 1. Reactions do not occur under normal temperature and humidity conditions. That is, Compound 2 is an extremely stable compound under that environment. Therefore, in the recording medium, under normal temperature and humidity conditions, the coupling-inactive compound 2 does not undergo a pre-coupling reaction with compound 1, forming a system with excellent storage stability. When heat is applied to this system, the reactions of Schemes 1 and 2 occur instantaneously to form an azo dye (compound 6), so a system with extremely high color development sensitivity can be constructed.

Therefore, when manufacturing a recording medium, a single coating solution can be produced even if the heat developer is alkaline without using the microcapsule method. That is, regardless of whether the coating liquid is water-based or solvent-based, the coating liquid is stable because compounds that can become coupling active couplers when heated are inert and chemically stable.

A single recording layer can be manufactured.

Furthermore, since the thermosensitive recording material of the present invention has the above-mentioned characteristics, if it is desired to impart water resistance to the recording layer of the recording material, this can be achieved by including a water-resistant thermoplastic resin. By selecting a thermoplastic resin that is compatible with the support, the mechanical strength of the recording layer of the recording medium can be obtained. That is, it is possible to impart desired durability to the recording layer of a recording medium by very easily selecting a thermoplastic resin as a polymeric binder.

Below, one recording material used in the present invention will be described in detail.

The carbamate ester compound used in the present invention, which can become a coupling active coupler when heated, is a mixture of an aromatic hydroxy compound (Ar-OH) and an aromatic isocyanate compound (Ar'-NCO) represented by the following general formula. It is a reaction product.

Ar-0-C-NH-Ar' (Ar, Ar' represent substituted or unsubstituted aromatic hydrocarbon groups.) The aromatic hydroxy compound can react with a diazo compound to form an azo dye. Any compound can be used. For example, 2.3-dihydroxynaphthalene, 2.2', 4.4'-tetrahydroxydiphenyl sulfide, phloroglyside, phlorogluside, resorcinacetamidophenol, dimethoxyphenol, hydroxynaphthalene, 2-methoxyphenol, 2-hydroxynaphthalene-3 -carboylanilide, 2-hydroxynaphthalene-3-carboyl-2'-methylanilide, 2,3-dihydroxynaphthalene-6-sulfamoyl, 2-hydroxyanthracene-5-carboyl-1-methylanilide, 1-oxynaphthyl- 4-7 enyl ketone.

Examples include 2-hydroxynaphthalene-3-carboylphenyl ester and 4-hydroxy-N-phenyl-quinolone-2.

On the other hand, aromatic incyanate compounds include, for example, phenyl isocyanate, P7 promophenyl isocyanate, 2
．． 5-dimethylphenyl isocyanate, 〇-ethoxyphenyl isocyanate, P-tolyl isocyanate,
Examples include tolylene diinocyanate, diphenylmethane diisocyanate, 2,5-dimethyl-P-phenylene diinocyanate, and the like.

The diazo compound used in the present invention is a compound that can be decomposed by actinic rays, and in particular, a diazonium salt represented by the general formula ArN2X-, and a compound that can be decomposed by actinic rays is effective. In this general formula, ArN
2 represents an aromatic diazonium group, and 2 represents an acid anion. Specifically, 4-diazo-1-benzoylaminobenzene, 4-diazo-3-methoxy-4'-methoxybenzoylaminobenzene, 4-sia:/-1-
Toluylmercaptobenzene, t4-diazo-1-dimethylaminobenzene, 4-diazo-1-dieflL, aminobenzene 1,4-diazo-1-ethylhydroxyethylaminebenzene, 4-diazo-1-ethylbenzylaminobenzene, 4 -diazo-1-anilinobenzene,
4-Diazo-1-4'-methoxybenzoylamino-2
, 5-jethoxybenzene, 4-diazo-1-morpholinobenzene, 4-diazo-1-morpholino-2,5-diisopropylbenzene, 4-diazo-1-morpholino-
2,5-shifted xybenzene, 4-diazo-1-morpholino-2,5-jethoxybenzene, 4-diazo-1-
Toluylmercapto-2,5-jethoxybenzene, 4
-Diazo-1-methoxyanilinobenzene, 4-diazo-1-pyrrolidino-2-methylbenzene, 4-diazo-
Examples include 1-pyrrolidino-2-methoxybenzene. Specific examples of acid anions include BF; , P
Examples include FT, C7H505803 (sulfosalcylic acid ion), but the agent is not limited to these as long as it is a dissolving or insolubilizing agent in water.

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

Specifically, organic amines, guanidines, imidacillins, imidazoles, and triazoles.

These include piperidines, amidines, morpholines, biquananides, guanylureas and their salts.

Preferably, a salt of a polybasic acid having a first-order dissociation constant of 2 x 10 to 1 x 10-4 and an alkyl-substituted guanidine represented by the general formula % is most suitable.

More specifically, the alkyl-substituted guanidines 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, etc.

On the other hand, as a polybasic acid having a first-order dissociation constant of 2 x 10''-' to 1 x 10-' that can form a salt with an alkyl-substituted guanidine, for example, 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.

The acid used in the present invention is used as an acid catalyst for thermally chemically changing the coupler used in the present invention to form a coupling-active aromatic hydroxy compound, and as an acid stabilizer. It is used as a. Specifically, para-toluenesulfonic acid, citric acid, gluconic acid, oxalic acid, tartaric acid, sulfamic acid, hydroxylamine hydrochloride, and boric acid.

Phosphoric acid etc. 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 harm your sexuality.

The polymer binder used in the present invention not only provides adhesiveness between the recording material and the support.

It is used to impart mechanical strength, water resistance, and solvent resistance to recording media. Therefore, any polymer binder can be selected depending on the purpose of use. Specifically, polyvinyl alcohol, hydroxyethyl cellulose,
Polyvinyl alcohol, gum arabic, polyvinyl acetate emulsion, methylcellulose, ethylcellulose,
Polyvinyl butyral, polyvinyl acetate, polystyrene, nitrocellulose, cellulose acetate)7'
Examples include tileitopolymer, salt-and-acetate picopolymer, polymethacrylic acid ester, and the like.

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

A coating solution in which a composition for forming a recording layer consisting of a diazo compound, a coupler, a thermal developer, a polymeric binder, etc. is dissolved in water or an organic solvent or uniformly dispersed in a dispersion device is applied to paper, glass, etc. A heat-sensitive recording material can be produced by applying the composition onto a support such as a film or sheet using a coating machine and drying it at a low temperature. Furthermore, it is also possible to provide a protective layer on the recording layer.

(Effects of the Invention) The recording medium of the present invention has a simple mechanism because it forms images by thermal printing and optical fixation, and is maintenance-free because there are no consumables. Furthermore, since the formed image is fixed, a stable permanent image can be provided. Furthermore, the recording medium of the present invention has excellent storage stability.

Moreover, the coloring sensitivity is high. Furthermore, since the mechanical strength and water resistance of the recording medium can be arbitrarily designed, a practical recording medium can be provided. Therefore, it can be used in an extremely wide range of application fields, such as recording media for various printers, tickets, cards, and sticker-less commuter passes that require anti-counterfeiting measures and durability of the recording media.

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

<Example 1> (1) Preparation of a dispersion of a diazo compound 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.

(2) Preparation of carbamate ester compound and thermal developer The above composition was pulverized and dispersed in a sand mill for 3 hours to obtain a dispersion having an average particle size of 25 μm.

■Formulation of recording layer coating solution A coating solution having the above composition is coated on high-quality paper that has been precoated with P←A to a dry weight of 7 g/d, and dried at a low temperature to form heat-sensitive recording paper. I got it.

<Example 2> A thermosensitive recording paper was obtained in the same manner as in Example 1, except that in step (2) of Example 1, a Nisder carbamate compound made of the paper with the following structure was used.

<Example 3> A thermosensitive recording paper was obtained in the same manner as in Example 1 except that a carbamate ester compound having the following structural formula was used in step (2) of Example 1.

<Example 4> A thermosensitive recording paper was obtained in the same manner as in Example 1 except that in step (2) of Example 1, a carbamate ester compound having the following structural formula was used.

<Example 5> ■Adjustment of coating solution for diazo compound A coating liquid was obtained by dissolving the above composition.

(2) Preparation of dispersion of carbamate ester compound and thermal developer The above composition was pulverized and dispersed in a sand mill for 3 hours to obtain a dispersion having an average particle size of 2 μm.

■Formulation of recording layer coating solution A coating solution having the above composition was coated onto a 188μ white polyester film using a wire bar to give a dry weight of 7 I/d, and dried at low temperature to form a heat-sensitive recording film. Obtained.

Comparative Example> Example (a heat-sensitive recording film was obtained in the same manner as in Example 5 except that a compound having the following structural formula was used in place of the carbamate ester compound in 5. (■)) (Test method) A Toshiba thermal simulator (
Printing conditions, applied voltage 14V, 1ms 0N10FF
) was used for thermal printing, and the entire surface was exposed to light using a Rifpee Hi-Start type 4 (Ricoh ■!B) to fix it. The reverse density of one image area of the obtained recorded image was measured using Macbeth RD514. The results are shown in Table 1.

Next, in order to check the shelf life of the thermosensitive recording material, the initial skin density (
Capri) and the capri after leaving them in a constant temperature and humidity chamber at 40°C and 90 RH for 48 hours were measured using the Macbeth RD514 to observe changes in the capri.

The results are shown in Table 1.

<Table 1> As shown in Table 1, the thermosensitive recording material of the present invention using a pre-coupler in which a coupling-active aromatic hydroxy compound is converted into a coupling-inactive carbamate ester compound has a coupling-active aromatic hydroxy compound. A comparative example in which the compound was used as it was had severe initial capri and was not subject to evaluation. This is because pre-coupling occurs in the coating liquid, and the recording medium coated with this has already had high-density capri on the entire surface. but.

For example, as shown in Example 5, the coating liquid of the present invention has stability despite having the same composition as the comparative example except for the coupler, and the resulting recording material has no background capri and has high whiteness. It also has excellent storage stability and color development sensitivity. From the above results, 1. The heat-sensitive recording material of the present invention not only has storage stability and color development sensitivity, but also has durability depending on the purpose of use because water or organic solvents can be used as a coating solvent. properties, such as water resistance, alcohol resistance,
It will be appreciated that mechanical properties can be easily obtained by selection of the polymeric binder and support.

Claims (1)

[Scope of Claims] 1) A support comprising a diazo compound, a thermal developer, an acid, a polymeric binder, and a carbamate ester represented by the following general formula, which can become a coupling active coupler when heated. Thermosensitive recording material characterized by being provided with a recording layer ▲ Contains mathematical formulas, chemical formulas, tables, etc. ▼ (Ar and Ar' represent substituted or unsubstituted aromatic hydrocarbon groups.) 2) Diazo compound is a diazonium salt represented by the following general formula, and is a compound that can be decomposed by actinic rays.ArN_2^+X^- (wherein ArN_2^ + is aromatic diazonium salt, X^-
represents an acid anion. )