JPH0720737B2 - Thermal recording - Google Patents

Description

TECHNICAL FIELD The present invention relates to a thermal recording material, and particularly to thermal printing,
The present invention relates to a diazo type thermosensitive recording material which can be fixed by light to form a permanent image. More specifically, the present invention relates to a thermosensitive recording medium which has excellent storage stability, high color-developing sensitivity, and can optionally have durability after recording.

(Prior Art and Problems) The thermal recording method is widely used in the field of facsimiles and various printers because it has the advantages of a simple mechanism, a dry method, and maintenance-free. In this process, leuco dye-based thermal papers are widely used. However, the recorded image cannot be fixed. if,
After recording, if it is exposed to heat or organic solvent, it will recolor or fade. Therefore, its field of use was limited to temporary information transmission and recording. As a method of compensating for this drawback, there is a method of using a diazo type thermal recording medium capable of forming a permanent image by thermal printing and optical fixing, and various methods have been disclosed. The diazo-type heat-sensitive recording material is a recording material in which a recording layer comprising a diazo compound, a coupler, a heat developing agent and the like is provided on a support, and its storage stability and color developing sensitivity depend on the characteristics of the heat developing agent. When the heat developer is water-soluble, the recording medium gradually undergoes precoupling during storage due to humidity,
Undesirable fog occurs. Therefore, as a method of compensating for the drawback, as disclosed in JP-A-57-123086, all recording materials are treated with water insolubilization, and in particular, they are preserved by using a water-soluble guanidine compound as a heat developing agent. There are attempts to improve stability. However, since a recording layer having a two-layer structure is used in manufacturing the recording body, the coloring sensitivity is sacrificed. Even if an attempt is made to increase the color development sensitivity by using a single recording layer, the guanidine compound, which is a heat developing agent, is alkaline, so pre-coupling occurs in the coating liquid (even if it is a dispersion type) and color development occurs. It has the drawback of Further, as disclosed in JP-A-59-190886, which has both storage stability and color development sensitivity,
Among the diazo compounds, couplers, and thermal developers, there is a method in which one kind is contained in microcapsules or two kinds are contained in the same or different microcapsules. However, since the microcapsules are used, a water-dispersed type coating liquid is inevitable in manufacturing the recording material.
Therefore, the obtained recording body lacks water resistance and mechanical strength (rubbing resistance, scratch resistance, etc.). This is particularly noticeable when a plastic sheet is used as the support. Therefore, it has a drawback that it cannot be used for applications requiring durability after recording.

(Object of the Invention) The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide a thermosensitive recording medium having high color development sensitivity and excellent storage stability without fogging due to precoupling under practical temperature and humidity conditions. Second of the present invention
The object of (1) is to provide a heat-sensitive recording material having excellent production suitability, which can obtain a single recording layer regardless of whether the coating liquid is water-based or solvent-based in producing the recording material.

(Summary of the Invention) A heat-sensitive recording material of the present invention for achieving the above object comprises a support, a diazo compound, an acid, a heat developing agent, a polymer binder,
And at least one derivative selected from a tertiary ether derivative, an acetal derivative, a ketal derivative and an alkoxymethyl ether derivative of an aromatic hydroxy compound which can be a coupling active coupler when heated under an acid catalyst. Is provided.

(Detailed Description of the Invention) The thermal recording material of the present invention will be described in detail below.

Compounds obtained by substituting the hydroxy group of aromatic hydroxy compounds with tertiary ethers, acetals, ketals, and alkoxymethyl ethers, etc., undergo an instant chemical reaction at a temperature of about 100 ° C under an acid catalyst to produce aromatic hydroxy compounds. It is known to change into compounds. For example, `` Smith, R.
A.:J.Chem.Soc., 55: 3718-3721 (1933), Ingold, CK, S
tructure and Mechanism in Organic Chemistry, C
ormell University Press Ithaca.NY, 1953, pp618
−619. ”And the like. By applying these reactions, a compound obtained by substituting a hydroxy group of an aromatic hydroxy compound, which is a coupling active coupler, with a coupling inactive tertiary ether, acetal, ketal, or alkoxymethyl ether is In a system consisting of a diazo compound, an acid, and a thermal developer, the present invention was found to change into a coupling active coupler (aromatic hydroxy compound) when heated, and react with the diazo compound to form a diazo dye, thereby achieving the present invention. We were able to.

Hereinafter, the present invention, represented by the following general formula, which can be a coupling active coupler on heating on a support, a diazo compound, a thermal developer, a polymer binder, and an acid catalyst, A heat-sensitive recording material comprising a recording layer containing at least one derivative selected from tertiary ether derivatives, acetal derivatives, ketal derivatives and alkoxymethyl ether derivatives of aromatic hydroxy compounds. A detailed example will be described.

_{Ar-O-CH 2 O-} R 9 alkoxymethyl ether derivative _{(R 1, R 2, R} 3, R 4, R 5, R 6, R 7, R 8 and R ₉ are ants files Tech group other than a hydrogen atom 2,5-dibutoxy-4-morpholinobenzenediazonium (compound 1) as a diazo compound, and 2-hydroxynaphthalene substituted by an acetal as a compound capable of forming a coupling active coupler when heated under an acid catalyst. The image forming reaction of a recording medium comprising a recording layer of -3-carboylanilide (compound 2), paratoluenesulfonic acid (compound 3) as an acid, and octadecylguanidine tartrate salt (compound 4) as a thermal developer is represented by the following formula. It is represented by.

Scheme 1 Scheme 2 Scheme 3 1) In the scheme, when the recording layer is heated with a hot plate at 100 ° C., the compound 2 undergoes the reaction of the scheme 1 in the presence of the compound 3 to become 2-hydroxynaphthalene-3-carboylanilide (compound 5). . [Coupling Active Coupler] 2) In Scheme 2, compound 5 undergoes a coupling reaction with compound 1 in the presence of compound 4 to form a blue azo dye (compound 6).

3) In Scheme 3, compound 1 becomes a colorless compound (compound 7) by irradiating the entire surface after thermal printing with active light such as a high pressure mercury lamp.

In the thermosensitive recording medium of the present invention, a permanent image is formed by the image forming steps 1) -2) -3) above. In these reactions, the reaction does not occur under normal temperature and humidity conditions. That is, the compound 2 is a very stable compound under the environment. Therefore, in the recording medium, the coupling-inactive compound 2 does not undergo a pre-coupling reaction with the compound 1 under normal temperature and humidity conditions, and constitutes a system having excellent storage stability. When heat is applied to this system, schemes 1 and 2
Since the reaction of (2) occurs instantly to form an azo dye (Compound 6), a system having extremely high color development sensitivity can be constructed. Therefore, in producing a recording body, a single coating solution can be formed even if the thermal developer is alkaline, without using the technique of microcapsules. That is, regardless of whether the coating liquid is water-based or solvent-based, the stability of the coating liquid is stable because the compound that can be a coupling active coupler when heated under an acid catalyst is inactive and chemically stable. Yes, a single recording layer can be manufactured.

Further, since the thermosensitive recording medium of the present invention has the above-mentioned characteristics, it can be achieved by adding a water-resistant thermoplastic resin to impart water resistance to the recording layer of the recording medium. The mechanical strength of the recording layer of the recording medium can be obtained by selecting a thermoplastic resin compatible with the support.

That is, the desired durability of the recording layer of the recording medium can be imparted by selecting the thermoplastic resin as the polymer binder very easily.

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

The compound capable of forming a coupling active coupler upon heating under the acid catalyst used in the present invention is a tertiary ether derivative, acetal derivative, tital derivative, or alkoxymethyl derivative of an aromatic hydroxy compound represented by the following general formula. It is an ether derivative.

_{Ar-O-CH 2 O-} R 9 alkoxymethyl ether derivatives (aromatic hydroxy compounds that can be a coupler as _{Ar-OH, R 1, R} 2, R 3, R 4, R 5, R 6, R 7, R ₈ and R ₉ represent an alyphatec group other than hydrogen atom.) These compounds undergo a chemical change instantly at a temperature of about 100 ° C under an acid catalyst to form a coupling active aromatic hydroxy compound. I will get it. The aromatic hydroxy compound capable of forming the above-mentioned tertiary ether derivative, acetal derivative, ketal derivative and alkoxymethyl ether derivative is any compound capable of reacting with a diazo compound to form an azo dye. Can be used.

For example, 2,3-dihydroxynaphthalene, 2,2'-4-4 '
-Tetrahydroxydiphenyl sulfide, phloroglyside, 4-hydroxy-N-methyl-quinolone-2,
1-hydroxynaphthalene-2-carboylphenyl ester, resorcinacetamidophenol, dimethoxyphenol, 2,2'-trimethylene-dioxy-diphenol, 2-hydroxynaphthalene, 1-hydroxynaphthalene, 2-methoxy-phenol, 2-hydroxy Naphthalene-3-carboylanilide, 2-hydroxynaphthalene-3-carboyl-2'-methylanilide, 2-hydroxynaphthalene-3-carboyl-2 '
-Ethoxyanilide, 2,3-dihydroxynaphthalene-
6-sulfamoyl, 2-hydroxyanthracene-3
-Carboyl-2'-methylanilide, 1-oxynaphthyl-4-phenylketone, 2-hydroxynaphthalene-3-carboyl-phenyl ester, 4-hydroxy-N-phenyl-quinolone-2 and the like can be mentioned.

The aromatic diazo compound used in the present invention has the general formula ▲ ArN ⁺ ₂
▼ X ^- is a diazonium salt represented by a compound which can be decomposed by the active rays. In the formula ▲ ArN ⁺ ₂ ▼
Represents an aromatic diazonium group, and X ⁻ represents an acid anion. Specifically, 4-diazo-1-benzoylaminobenzene, 4-diazo-3-methoxy-1-4'-methoxybenzoylaminobenzene, 4-diazo-1-toluylmercaptobenzene, 4-diazo-1-dimethyl. Aminobenzene, 4-diazo-1-diethylaminobenzene, 4-diazo-1-ethylhydroxyethylaminobenzene, 4-diazo-1-ethylbenzylaminobenzene, 4-diazo-1-anilinobenzene, 4-diazo-
1-4'-methoxybenzoylamino-2,5-diethoxybenzene, 4-diazo-1-morpholinobenzene, 4
-Diazo-1-morpholino-2,5-diisopropylbenzene, 4-diazo-1-morpholino-2,5-dibutoxybenzene, 4-diazo-1-morpholino-2,5-diethoxybenzene, 4-diazo- 1-Toluyl mercapto-
2,5-diethoxybenzene, 4-diazo-1-methoxyanilinobenzene, 4-diazo-1-pyrrolidino-2-
Methylbenzene, 4-diazo-1-pyrrolidino-2-methoxybenzene and the like can be mentioned. Specific examples of the anions _{^{▲ BF - 4 ▼, ▲ PF}} - 6 ▼, ▲ C 7 H 5 O 3 SO - 3
(Sulfosulfate ion) and the like, but not limited to these as long as they are sparingly soluble or insolubilizing agents in water.

The thermal developer used in the present invention is a compound which is sparingly water-soluble or water-insoluble, and a compound which creates a coupling active atmosphere when heated is used.

Physically, organic amines, guanidines, imidazolines, imidazoles, triazoles, piperidines,
Examples include amidines, morpholines, biquanides, guanylureas and salts thereof. Preferably first dissociation constant 2
× 10 ^-1 to 1 × 10 ^-4 polybasic acid and general formula The salt with the alkyl-substituted guanidine represented by is most suitable.

More specifically, as the alkyl-substituted guanidine, for example, octylguanidine, nonylguanidine, decylguanidine, undecylguanidine, laurylguanidine,
Tridecylguanidine, myristylguanidine, hexadecylguanidine, octadecylguanidine, aicosylguanidine, docosylguanidine, dioctylguanidine, dioctadecylguanidine, N-methyl-N-octadecylguanidine, N-methyl-N-decylguanidine, N, N -Didecylguanidine and the like.

On the other hand, as a polybasic acid having a primary dissociation constant of 2 × 10 ^-1 to 1 × 10 ^-4 , which 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 and the like are suitable.

The acid used in the present invention is, as one, an acid catalyst for chemically changing the coupler used in the present invention under heat to form a coupling active aromatic hydroxy compound, and one is an acid stabilizer. Is used as. Specific examples include paratoluenesulfonic acid, citric acid, gluconic acid, oxalic acid, tartaric acid, sulfamic acid, hydroxylamine hydrochloride, boric acid, phosphoric acid and the like. Further, in order to enhance the storage stability of the recording material after recording, thiourea, L-
The use of ascorbic acid, urea, allyl isothiocyanate or the like does not impair the color development sensitivity and storage stability of the recording material of the present invention.

The polymer binder used in the present invention is used not only for imparting adhesiveness between the recording material and the support, but also for imparting mechanical strength, water resistance and solvent resistance of the recording material. is there. Therefore, the polymer binder can be arbitrarily selected according to the purpose of use. Specifically, polyvinyl alcohol, hydroxyethyl cellulose, polyvinyl alcohol, gum arabic, polyvinyl acetate emulsion, methyl cellulose, ethyl cellulose, polyvinyl butyral, polyvinyl acetate, polystyrene, nitrocellulose, cellulose acetate butyrate polymer, salt vinegar picopolymer, poly Methacrylic acid ester and the like can be mentioned.

Next, as a method for coating the recording layer on the support, known coating methods can be used. Specifically, a coating liquid in which a composition for forming a recording layer, which comprises a diazo compound, a coupler, a heat developing agent acid, and a polymer binder, is dissolved in water or an organic solvent or uniformly dispersed in a disperser. A thermosensitive recording medium can be manufactured by applying a coating liquid onto a support such as paper, glass, film or sheet with a coating liquid and drying at low temperature. Further, it is possible to provide a protective layer on the recording layer.

(Effect of the Invention) The recording medium of the present invention has a simple mechanism for forming an image by thermal printing and optical fixing, and is maintenance-free because there are no consumables. Further, since the formed image is fixed, a stable permanent image can be provided. Furthermore, the recording material of the present invention has excellent storage stability and high color development sensitivity. In addition, since the mechanical strength and water resistance of the recording material can be arbitrarily designed, it is possible to provide a practical recording material. Therefore, it can be used in a very wide range of applications as a recording medium for various printers, a ticket for which anti-counterfeiting measures and durability of the recording medium are required, a recording medium for cards and sealless commuter pass.

Examples Examples of the present invention will be shown below. In addition, "part" in each example
Means parts by weight.

<Example 1> Preparation of dispersion liquid of diazo compound Grind and disperse the above composition in a sand mill for 2 hours and average 1μ
A uniform dispersion of

Preparation of dispersion liquid for coupler and heat developer The above composition was ground and dispersed in a sand mill for 3 hours to obtain a dispersion liquid having an average particle size of 2.5 μ.

Mixing of coating liquid for recording layer A coating solution having the above composition was applied to a high-quality paper pre-coated with PVA so that the dry weight was 7 g / m ² , and dried at a low temperature to obtain a thermosensitive recording paper.

<Example 2> A thermal recording paper was obtained in the same manner as in Example 1 except that the coupler having the following structural formula was used.

<Example 3> A thermal recording paper was obtained in the same manner as in Example 1, except that the coupler having the following structural formula was used.

<Example 4> A thermal recording paper was obtained in the same manner as in Example 1 except that a coupler having the following structural formula was used.

<Example 5> Preparation of coating liquid of diazo compound Diazonium salt having the following structural formula The above composition was dissolved to obtain a coating liquid.

Preparation of coupler and heat developer dispersion The above composition was ground and dispersed in a sand mill for 3 hours to obtain a dispersion liquid having an average particle diameter of 2μ.

Mixing of coating liquid for recording layer A coating liquid having the above composition was coated on a 188 μ polyester film with a wire bar so that the dry weight was 7 g / m ² , and dried at a low temperature to obtain a thermosensitive recording film.

<Comparative Example-1> A thermosensitive recording film was obtained in the same manner as in Example 5, except that a coupler having the following structural formula was used.

Comparative Example-2 A thermosensitive recording film was obtained under the same conditions as in Example 5, except that the coupler having the following structural formula was used in Example 5.

(Test method) The thermal recording material thus obtained was subjected to thermal printing using a thermal simulator made by Toshiba (printing conditions, applied voltage 14V, 1ms ON / OFF), and using Ricopy High Start Type 4 (made by Ricoh Co., Ltd.). The entire surface was exposed and fixed. The reflection density of the image portion of the obtained recorded image was measured with Macbeth RD514. The results are shown in Table 1.

Next, in order to check the raw storability, the initial background density (fog) of the thermosensitive recording medium was recorded in a thermo-hygrostat at 40 ° C and 90% RH.
The fog after leaving for a while was measured with a Macbeth RD514, and the change in the fog was observed. The results are shown in Table 1.

As can be seen from Table 1, the heat-sensitive transfer recording material of the present invention using a coupler having a coupling active aromatic hydroxy compound as a coupling inactive ether, acetal, ketal and alkoxymethyl ether derivative is a coupling active aromatic compound. It was possible to obtain a heat-sensitive recording material having excellent storage stability and high color-developing sensitivity as compared with the comparative example using the hydroxy compound as it was. Here, the comparative example was out of the scope of evaluation because the initial fog was severe. The reason for this is that since the organic solvent is used as the coating solvent in the comparative example, the diazo compound and the thermal developer are dissolved and pre-coupling occurs in the coating liquid before coating. This is because the processed recording material had already had fog with a high density on the entire surface. However, according to the present invention, as shown in Example 5, for example, the coating liquid is stable even though the composition is the same as that of Comparative Example except for the coupler, and the obtained recording material has less background fog and is storage stable. It has excellent properties and color development sensitivity.

From the above results, the thermosensitive recording medium of the present invention not only has storage stability and color development sensitivity, but since it is possible to use water or an organic solvent as a coating solvent, durability depending on the purpose of use. It will be understood that, for example, water resistance, alcohol resistance, mechanical properties, etc. can be easily obtained by selecting the polymer binder and the support.

Claims (2)

[Claims] 1. Tertiary aromatic hydroxy compound which can be a coupling active coupler on heating, on a support, with a diazo compound, an acid, a heat developing agent, a polymeric binder, and an acid catalyst. A thermosensitive recording medium comprising a recording layer containing at least one derivative selected from an ether derivative, an acetal derivative, a ketal derivative and an alkoxymethyl ether derivative. 2. The heat-sensitive recording material according to claim 1, wherein the diazo compound is a diazonium salt represented by the following general formula and is a compound which can be decomposed by actinic rays. ArN ₂ ⁺ X ^- (wherein ArN ₂ ¹ aromatic diazonium salt, X represents an acid anion)