JPH042114B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a diazo thermosensitive recording material having excellent storage stability. [Technical background of the invention and its problems] In recent years, high-speed printers, facsimile machines, etc. have made remarkable progress in response to society's demand for outputting large amounts of information as hard copies as quickly as possible. Electrophotography, electrostatic recording, discharge recording, inkjet recording, thermosensitive recording, and the like are known as methods for forming images on recording media according to electrical information, such as high-speed printers and facsimiles. Among these methods, the thermal recording method has been rapidly becoming popular in recent years because the apparatus is relatively simple and the recording paper is also relatively inexpensive. As one method of the heat-sensitive recording method, a heat-sensitive recording sheet made by combining a color-forming substance such as crystal violet lactone and a phenolic compound such as bisphenol A is described in, for example, Japanese Patent Publication No. 14039/1983. It is already known. These thermosensitive recording sheets are currently widely used as office copy paper, recording paper for various recorders, electrocardiographs, calculators, computer terminals, facsimiles, and the like. However, with the above conventional method, if the background is heated incorrectly after printing, the background may become colored and the print may become unreadable, or there is a possibility that it may be tampered with after printing.
Improvements are strongly desired. The present inventors conducted research with the intention of providing a fixable heat-sensitive recording medium that solved this problem, and first developed a guanidine derivative having a specific general formula as a basic substance that promotes the reaction between a diazonium salt and a coupler compound. It has already been found and proposed that by using this method, it is possible to provide a fixable heat-sensitive recording medium that is highly sensitive and has excellent storage stability. (Unexamined Japanese Patent Publication No. 57-
45094, 125091) However, in recent years, in the field of thermal recording, there has been an increasing demand for higher color development sensitivity, and when attempting to obtain a diazo thermosensitive recording material with even higher color development sensitivity, storage stability often deteriorates and background fog occurs. Occasionally, this may occur. [Object of the Invention] An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a diazo thermosensitive recording material having high sensitivity and excellent storage stability. [Structure and operation of the invention] That is, the present invention mainly consists of a fine powder dispersion of a diazonium salt, a coupler compound, and a hydrophobic organic basic compound that melts with heat and exhibits a basic atmosphere as a color developer. A diazo thermosensitive recording material comprising a photosensitive and thermosensitive layer provided on a support, characterized by excellent storage stability by containing at least one aromatic carboxylic acid derivative of the following general formula () in the photosensitive and thermosensitive layer. The object of the present invention is to provide a diazo thermosensitive recording material. General formula () l is an integer of 1 to 3, m is 2 or 3 The light and heat sensitive layer of the present invention mainly contains a diazonium salt, a coupler compound, a color developer, etc., and these are formed as a single layer on a support as a light and heat sensitive layer. Alternatively, the main component may be divided into two layers or multiple layers and provided on the support. Knowing that the effect of improving storage stability due to the addition of aromatic carboxylic acid is observed not only when the hydrophobic guanidine derivative but also widely known organic basic compounds are used as a color developer, This led to the present invention. Particularly preferred organic basic compounds include the following guanidine derivatives. General formula () or general formula () [In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are hydrogen, alkyl having 18 or less carbon atoms, cyclic alkyl, aryl,
Represents aralkyl, amino, alkylamino, acylamino, carbamoylamino, heterocyclic residue,
R ₆ is lower alkylene, phenylene, naphthylene or

[Formula] (in the formula, X represents lower alkylene, SO ₂ , S ₂ , S, O, -NH- or a single bond), and the aryl group in the formula is lower alkyl, alkoxy, nitro, acylamino, alkylamino Also included are those having substituents selected from groups and halogens. ] The aromatic carboxylic acid derivative used in the present invention is added at a weight ratio of 3 to the organic basic compound.
It is desirable that the content be within the range of ~30%; if it is less than 3%, the effect of improving storage stability, which is the objective of the present invention, will be small, and if it is more than 30%, the color development sensitivity will decrease. Specific examples of aromatic carboxylic acid derivatives used in the present invention include α-resorcinic acid, β-resorcinic acid, γ-resorcinic acid, and the like. These aromatic carboxylic acid derivatives are added to the photosensitive and thermosensitive layer in a state dissolved in water or an organic solvent, or dispersed to a particle size of 10μ or less using a dispersion means such as an attritor, a ball mill, or a sand glider. It can be added to the light and heat sensitive layer as a fine particle dispersion. The desired effect can be obtained even if the aromatic carboxylic acid derivative is contained in a layer containing a diazonium salt or an acid compound to prevent precoupling as the main component.
When a fine particle dispersion of an organic basic compound is contained in a layer containing a color developer, a greater effect on improving the storage stability of a fixable heat-sensitive recording material can be obtained. Particularly in a weight ratio of 3 to 3 to an organic basic compound
Adding aromatic carboxylic acid derivatives within the range of 30% can improve storage stability without reducing color development sensitivity. This is probably due to the decrease in storage stability that occurs during dispersion of organic basic compounds. This is because the aromatic carboxylic acid derivative neutralizes extremely small dispersed particles or substances dissolved in the dispersion solvent, which have a large effect on coloring, and also has some coupling ability itself, which can prevent a decrease in color development sensitivity. Conceivable. Regarding the aromatic carboxylic acid, alone,
Or by combining aromatic carboxylic acids,
Furthermore, it can be used co-dispersed with an organic base compound, a coupler compound, or other compounds added in a dispersed state if necessary. As the diazonium salt used in the present invention, any compound used in conventionally known diazo type copying materials can be used, but for example, those represented by the following general formula can be particularly preferably used. In the formula, R ₁ and R ₂ are alkyl groups having 1 to 5 carbon atoms,
or an alkoxyl group, or an oxyalkyl group, a benzyl group, a substituted benzyl group, a benzoyl group, a substituted benzoyl group, a phenyl group, a hydrogen atom, etc., and Y and Z are a halogen atom, an alkyl group having 1 to 5 carbon atoms, a carboxyl group , an alkoxyl group having 1 to 5 carbon atoms, a nitro group, an acetoxy group, etc., and m and n are 0 or a positive integer of 4 or less.
Also, X is Cl ^- , Br ^- , SO ₄ ^- , NO ₃ ^- , ClO ₄ ^- , BF ₄ ^-
Anions such as Zncl ₂ , CDCl ₂ or
Sncl ₄ etc. represent ions added to these anions. Specific examples include 4-N,N-dimethylaminobenzenediazonium chloride, 3-chloro-4
-N,N-dimethylaminobenzenediazonium chloride, 4-N,N-diethylaminobenzenediazonium chloride, 1,6-diethoxy-4
-N,N-diethylaminobenzenediazonium chloride, 4-N-ethyl-N-hydroxyethylaminobenzenediazonium chloride, 4-
N,N-diethoxyaminobenzenediazonium chloride, 4-phenylaminobenzenediazonium chloride, 4-N-(P-methoxyphenyl)
-aminobenzenediazonium chloride, etc. In the formula, R is -CH ₂ CH ₂ OCH ₂ CH ₂ -ya-
CH ₂ OCH ₂ CH ₂ −, −CH ₂ CH ₂ CH ₂ CH ₂ −, etc. X, Y, Z, m and n have the same meanings as in the general formula (). Specific compound examples include 4-morpholinobenzenediazonium chloride, 2,5-diethoxy-4-morpholinobenzenediazonium chloride, 4-oxazolidinobenzenediazonium chloride, and 3-methyl-4-piperidinopene. Examples include zendiazonium chloride. In the formula, R ₁ represents an alkyl group or an aryl group. Further, X, Y, Z, m and n have the same meanings as in the general formula (). Specific compound examples include 4-ethylmercapto-2,5-diethoxybenzenediazonium chloride, 4-tolylmercapto-2,5-diethoxybenzenediazonium chloride, and 4-benzylmercapto-2,5-dimethoxybenzenediazonium. chloride etc. These diazonium salts can be dissolved in water or an organic solvent, or dispersed in the form of fine particles in an appropriate solvent, and then coated on a support. The acid compound to be contained in the same layer as the diazonium salt in order to stabilize the diazonium salt and prevent pre-coupling may be any organic or inorganic acid compound used in conventionally known diazo type copying materials. Specific examples include tartaric acid, citric acid, boric acid, lactic acid, gluconic acid, phosphoric acid, trichloroacetic acid, dichloroacetic acid, cyanoacetic acid, oxalic acid, malonic acid, maleic acid, and the like. These acid compounds are preferably used in a weight ratio of 1.0% to 30%, more preferably 3 to 15%, based on the organic basic compound. Further, as the coupler compound which reacts with the diazonium salt to form an azo dye, any compound capable of coupling with the above-mentioned diazonium salt can be used. If the organic basic compound used as a color developer is soluble in the water or organic solvent used as a solvent for the coating solution when applied to the support, the pH of the coating solution will increase, causing fogging on the background and poor storage stability. Since this may cause deterioration, it is preferable that it exists as a discontinuous fine particle dispersion in the coating layer, and the solubility in water at 20°C is
If it is 1.0 g/l or less, it has good humidity and heat storage stability, and heterocyclic compounds such as aliphatic amines, pyrrolidine derivatives, imidazole derivatives, imidazoline derivatives, piperidine derivatives, etc. can also be suitably used, but in particular, compounds of the following general formula When the hydrophobic guanidine derivatives () and () are used as a color developer, it is possible to obtain a diazo-fixed thermosensitive recording material that has excellent storage stability under high temperature and high humidity conditions and develops color with high sensitivity. Further, as the color developer, one having a m.p in the range of 100 to 170°C can be particularly preferably used. The color developer may be dispersed alone using a dispersion means such as a ball mill, sand glider, or attritor, but aromatic carboxylic acid derivatives, coupler compounds,
If necessary, it may be co-dispersed with other additives. General formula () or general formula () [In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are hydrogen, alkyl having 18 or less carbon atoms, cyclic alkyl, aryl,
Represents aralkyl, amino, alkylamino, acylamino, carbamoylamino, heterocyclic residue,
R ₆ is lower alkylene, phenylene, naphthylene or

[Formula] (in the formula, X represents lower alkylene, SO ₂ , S ₂ , S, O, -NH- or a single bond), and the aryl group in the formula is lower alkyl, alkoxy, nitro, acylamino, alkylamino Also included are those having substituents selected from groups and halogens. ] Typical specific examples are shown in Table 1, but this does not limit the present invention. In the table

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Example 1 A photosensitive layer containing a diazonium salt was prepared with the following formulation, and the coating amount after drying on the support was 3.0 g/m ²
Apply it so that it looks like this. Citric acid 3g Thiourea 2g 2,5-diethoxy-4-morpholinobenzenediazonium tetrafluoroborate 2g Kaolin 5g 10% polyvinyl alcohol 30g Water 100ml A heat-sensitive layer containing a color developer prepared with the following formulation was placed on the above photosensitive layer. The coating amount after drying is 6.5
A diazo thermosensitive recording material is prepared by coating the solution at a concentration of g/m ² . Water 100g Kaolin 10g Solution A 6g Solution B 80g Solution C 4g 10% polyvinyl alcohol 120g 50% melamine-formalin waterproofing agent 2g For solutions A, B, and C, the following formulations were ground and dispersed in a ball mill for 48 hours. It was prepared by Part A 2-hydroxy-3-naphthoic acid-2'-ethoxyanilide 10g 10% methylcellulose 5g Water 15g Part B 80g (compounds in Table 1) Stearic acid amide 20g 10% methylcellulose 50g Water 150g Solution C β-resorcinic acid 10g 10% polyvinyl alcohol 5g Water 15g Example 2 Instead of using β-resorcinic acid in Solution C in Example 1 A diazo thermosensitive recording material was prepared in the same manner as in Example 1 except that α-resorcinic acid was used. Example 3 A dizo thermosensitive recording material was prepared in the same manner as in Example 1 except that γ-resorcinic acid was used instead of β-resorcinic acid in the C liquid. Comparative Example 1 A diazo thermosensitive recording material was obtained in the same manner as in Example 1 except that liquid C was not added. The thus obtained diazo-fixed heat-sensitive recording material was thermally printed using a facsimile (Toshiba KB-4800), and then the entire surface was exposed to ultraviolet light to decompose and fix the diazonium salt. The print density obtained as described above was measured using a Macbeth densitometer (RD-514), and the values are shown in Table 2. Table 2 also shows the results of the storage stability test. The storage stability test consists of a moisture and heat resistance test in which the sample is prepared by preparing the coating solution, applied and dried, and left in a dark place at 40℃ and 90% relative humidity for 24 hours.
Table 2 shows the results of a heat resistance test in which the samples were left in a dryer at ℃ for 24 hours.

〔Effect of the invention〕

As is clear from Table 2, the general formula () of the present invention
By adding the aromatic carboxylic acid shown in the following to the photosensitive and heat-sensitive layer, storage stability could be improved without reducing coloring sensitivity.

Claims (1)

[Scope of Claims] 1. A light and heat sensitive layer containing as main components a fine powder dispersion of a diazonium salt, a coupler compound, and a hydrophobic organic basic compound which melts with heat and exhibits a basic atmosphere as a color developer, as a support. The diazo thermosensitive recording material provided above is characterized in that the photosensitive thermosensitive layer contains at least one aromatic carboxylic acid derivative represented by the following general formula (). Diazo thermosensitive recording material. General formula () l is an integer of 1 to 3 m is 2 or 3 2 The diazo thermosensitive recording material according to claim 1, wherein the organic basic compound is a hydrophobic guanidine derivative represented by the following general formula () or (). General formula () General formula () [In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are hydrogen, alkyl having 18 or less carbon atoms, cyclic alkyl, aryl,
Represents aralkyl, amino, alkylamino, acylamino, carbamoylamino, heterocyclic residue,
R ₆ represents lower alkylene, phenylene, naphthylene, or [Formula] (wherein X represents lower alkylene, SO ₂ , S ₂ , S, O, -NH-, or a single bond), and the aryl group in the formula is lower Also included are those having substituents selected from alkyl, alkoxy, nitro, acylamino, alkylamino groups and halogen. ]