JPH0354075B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a diazo-based heat-sensitive recording material that has excellent black color development, as well as excellent storage stability and background discoloration. In addition to being used as copy paper for books and documents, thermosensitive recording materials are also used as output recording paper for electronic computers, facsimile machines, medical measuring machines, etc., as well as thermal recording magnetic ticket paper and thermal recording label paper. be done. In addition, heat-sensitive recording materials are also being considered for use as paper for creating securities, gift certificates, admission tickets, certificates, slips, etc. by taking advantage of their ease of automatic recording. In order to obtain high recording reliability, the heat-sensitive recording material must be able to be fixed. Conventionally, as fixable heat-sensitive recording materials, diazo-based materials that utilize a color-forming reaction between a diazo compound and a coupler are known. However, from a practical standpoint, conventional products are still unsatisfactory in terms of black color development, shelf life, and background discoloration. For example, when phloroglucin is used as a coupler, a black coloring recording material can be obtained, but this material has the problem of poor storage stability and background discoloration. On the other hand, it is known that a mixture of a blue color-forming coupler and a yellow color-forming coupler is used to obtain a black color-forming recording material, but satisfactory results are not obtained in this case either. That is, when trying to obtain a black color using such a mixed system, a mixed system of a blue coloring coupler made of 2,3-dihydroxynaphthalene-6-sulfonic acid and a yellow coloring coupler made of acetoacetanilide is used. However, in such a mixed system, the coupling speed with diazo is poor, resulting in a lack of concentration, and because it is easily soluble in water, it causes skin fogging. The present inventors have conducted extensive research in order to overcome the above-mentioned drawbacks seen in the prior art and to develop a diazo-based heat-sensitive recording material that is significantly improved in black color development and also has excellent storage stability and background discoloration. As a result of repeated research, the inventors discovered that the objective could be achieved by using a special combination of couplers and a thermofusible material, and were able to complete the present invention. That is, according to the present invention, in a diazo thermosensitive recording material provided with a thermosensitive coloring layer containing a diazo compound, a coupler, and a thermofusible substance, the coupler is made of a naphthol derivative represented by the following general formula (). A mixture of a blue color-forming coupler and a yellow color-forming coupler made of an anilide compound represented by the following general formula () is used, and the thermofusible substance is added in an amount of 5 to 30 parts by weight per 1 part by weight of the diazo compound. A diazo-based heat-sensitive recording material is provided, which is characterized in that it is used in a proportion of 50%. In the above general formula ( ⁾ , Aromatic groups (for example, when n = 0, unsubstituted phenyl or naphthyl, or halogen,
phenyl or naphthyl substituted with a substituent such as alkyl, aryl, alkoxy, nitro group, hydroxy group, alkoxycarbonyl group, sulfonic acid group, amidosulfonic acid group, and when n = 1, unsubstituted phenylene, naphthylene, bisphenylene,
or phenylene, naphthylene, bisphenylene, etc. substituted with the various substituents described above), or an alicyclic group (for example, when n=0, unsubstituted cyclohexyl, or substituted with the various substituents shown for the aromatic group) cyclohexyl etc., n=
In the case of 1, it is unsubstituted cyclohexylene or cyclohexylene substituted with the above-mentioned various substituents), and n is 0 or 1. Specific examples of naphthol derivatives represented by the general formula () include naphthol AS, naphthol AS-D, naphthol AS-OL, naphthol AS-RL, naphthol AS-PH, naphthol
AS-VL, naphthol AS-E, naphthol AS-
BS, naphthol AS-BR, naphthol AS-BO,
Naphthol AS-SW, Naphthol AS-TR, Naphthol AS-ITR, Naphthol AS-BG, Naphthol AS-KB, Naphthol AS-LC, Naphthol AS-LT, Naphthol AS-MX, Naphthol
In addition to AS-BM, naphthol AS-CA, etc., 3
-Hydroxy-2-naphthoic acid-3'-hydroxy-anilide, 3-hydroxy-2-naphthoic acid-
3'-acetyl-anilide, 3-hydroxy-2-
Naphthoic acid-3'-aminosulfo(-SO ₃ NH ₂ )-
Anilide, 3-hydroxy-6-bromo-2-naphthoic acid-6'-methoxy-anilide, 3-hydroxy-2-naphthoic acid-3'-hydroxy-4'-methyl-anilide, 3-hydroxy-2-naphthoic acid Acid-3'-methoxycarbonyl-anilide, 3-hydroxy-2-naphthoic acid-4'-sulfo-anilide, 3-hydroxy-6-sulfo-2-naphthoic acid-2'-methyl-anilide, 3-hydroxy- 2
-naphthoic acid-4'-methoxy-5'-hydroxy-
Examples include anilide. All of these naphthol derivatives form blue azo dyes when subjected to a color-forming reaction with a diazo compound. In the general formula ( ₎ , X ₁ and (alkoxy having 1 to 4 carbon atoms such as methoxy, ethoxy, propoxy, butoxy) or aryloxy (e.g. phenoxy, tolyloxy, etc.)
and R ² is the same aromatic group or alicyclic group as shown for R ¹ above, and preferably includes substituted or unsubstituted phenyl or cyclohexyl. Y is a cyano group (-CN) or an acyl group (for example, an aliphatic group having an alkyl group having 1 to 4 carbon atoms such as acetyl, propionyl, butyryl, valeryl, hexahydrobenzoyl, benzoyl,
It is an aromatic type having a phenyl group such as toluoyl, salicyloyl, or a phenyl group substituted with various substituents shown for R ¹ above. Specific examples of the anilide compound represented by the general formula () include the following. 4-Benzoylamino-2,5-diethoxy-
Acetoacetanilide 4-Benzoylamino-2,5-2,5-dimethoxy-benzoylacetanilide 4-(2'-chlorobenzoylamino)-2,5-
Dimethoxy-acetoacetanilide 4-Benzoylamino-(2'-chlorobenzoyl)acetanilide 4-Benzoylamino-acetoacetanilide 4-Benzoylamino-2,5-diethoxy-
Cyanoacetanilide 4-(p-methylbenzoylamino)-acetoacetanilide 4-Benzoylamino-2,5-dibutoxy-
Acetoacetanilide 4-(p-methoxybenzoylamino)-2,5
-diethoxy-acetoacetanilide 4-(p-methoxybenzoylamino)-2-chloro-5-butoxy-acetoacetanilide Any of the above-mentioned anilide compounds forms a yellow azo dye when subjected to a color-forming reaction with a diazo compound. In the present invention, the above-mentioned naphthol derivative and anilide compound are mixed and used as a coupler, but in this case, the ratio of the two is generally as follows:
The ratio is in the range of 1:5 to 5:1, and the mixture is mixed so as to obtain the required black color development. In the present invention, both the naphthol compound represented by the general formula () and the anilide compound represented by the general formula () have a larger molecular weight than phloroglucin, acetoacetanilide, etc. and are less soluble in water, so they have a long shelf life. To provide a stable mixed coupler that is excellent in water and resistant to oxidation. In the present invention, the above-described mixed coupler is used, and a relatively large amount of a thermofusible substance is used in order to enhance the color development of the mixed coupler. The amount of this thermofusible substance is 5 to 30 parts by weight, preferably 7 parts by weight, per 1 part by weight of the diazo compound.
~20 parts by weight. Further, the particles of the coupler are preferably fine particles of 10 μm or less. In addition, the heat-sensitive color forming layer as used in the present invention refers to one layer or a multilayer of two or more layers formed to support heat-sensitive color forming layer forming components such as a diazo compound, a coupler, and a thermofusible substance on a support. This means the entire coating layer. Accordingly, the components forming the thermosensitive coloring layer may be contained simultaneously in one coating layer, or appropriately separated and contained in two or more multilayer coating layers.
In the present invention, a heat-sensitive coloring layer having a two-layer structure is adopted, in which a diazo layer containing a diazo compound and a thermofusible substance is provided as the lower layer, and a coupler layer containing a mixed coupler and a thermofusible substance is provided on top of the diazo layer. is preferable. As the diazo compound used in the present invention,
A commonly used one, for example, one represented by the following general formula can be used. However, in the general formulas [], [], and [], R ₁ , R ₆ , and R ₈ are hydrogen, halogen, a C ₁ to _{C 5} alkyl group or an alkoxyl group, or

[Formula] or

[Formula] (R ₁₁ , R ₁₂ : Same as R ₂ ), R ₂ , R ₃ , R ₉ are hydrogen, halogen, C ₁ to C ₅ alkyl group or alkoxyl group, R ₄ and R ₅ are the same or different _C1 - _C5 alkyl group, hydroxyalkyl group, or

[Formula] (R ₁₃ : hydrogen, C ₁ to C ₃ alkyl group or alkoxyl group, or halogen), R ₇ is hydrogen, halogen, trifluoromethyl group, C ₁ to _{C 5} alkyl group or alkoxyl group, or ,

[Formula] R ₁₀ is

【formula】

【formula】

【formula】

【formula】

[Formula] or

[Liquid A]

1 part by weight Stearic acid amide 7 Vinyl chloride-vinyl acetate copolymer 5 Methyl cellosolub 87 The above composition was dispersed in a ball mill to prepare [Liquid A]. [Liquid B] Naphthol AS 2 parts by weight 4-Benzoylamino-2,5-diethoxy-acetoacetanilide 3 N-stearylbenzamide 10 Imidazole 5 Silica 5 Isobutylene maleic anhydride copolymer 5 Water 70 Above composition The material was dispersed in a ball mill to prepare [Liquid B]. A 50 g/m ² high-quality paper is undercoated with calcium carbonate and polyvinyl alcohol (PVA) to a dry weight of 2 g/m ² . On top of that, A
The liquid was coated and dried to a dry weight of 2.5 g/m ² , and then liquid B was further coated and dried to a dry weight of 2.0 g/m ² to obtain a thermal record. When the obtained heat-sensitive recording material was printed using a facsimile (RIFAX3300), it developed a black color. Furthermore, this was exposed with Ricopy High Start 100,
It took root. When measured with a Macbeth densitometer, the print density was 0.96 and the background density was 0.10. In addition, the thermal paper before exposure was heated at 40℃, humidity (RH) 90% and 60℃.
When exposed to light after being left in a dry environment for 24 hours, the skin density was 0.15 and 0.18, respectively.
Furthermore, the skin density was 0.12 after the thermal paper was pasted on the wall of an ordinary office for one month after being exposed to lightning. Example 2 [Liquid C] 1 part by weight stearamide 7 Acrylic-styrene copolymer emulsion (50
%) 10 Water 82 The above composition was dispersed in a ball mill to prepare [Liquid C]. A thermal paper was produced in the same manner as in Example 1 except that Liquid C was used instead of Liquid A in Example 1, and the thermal paper was tested. In the printing test, a print density of 0.90 and a background density of 0.11 were obtained, and in a storage test under conditions of 40℃ and 90% humidity (RH), a background density of 0.19 was obtained. In the storage test, a skin density of 0.21 was obtained.
In addition, in a long-term storage test for one month, a skin concentration of 0.15 was obtained. Example 3 In Example 1, instead of naphthol AS,
A product was obtained and tested in the same manner except that the naphthol derivative shown below was used, and the same results as in Example 1 were obtained in this case as well.

【table】

[Table] Example 4 A product was obtained in the same manner as in Example 1 except that the anilide compound shown below was used,
This test was conducted, and the same results as in Example 1 were obtained in this case as well.

【table】

[Table] Comparative Example 1 Dry weight using 3 parts by weight of phloroglucin instead of the two types of couplers used in Solution B of Example 1
A product was obtained and tested in the same manner except that the amount was 2.2 g/m ² . In the printing test, the printing density
1.05 and a skin density of 0.11 were obtained, and in a storage test under conditions of 40℃ and 90% humidity (RH), the skin density was 0.11.
A result of 0.26 was obtained, and in a storage test under dry conditions at 60°C, a skin concentration of 0.30 was obtained. In addition, in a long-term storage test for one month, a skin concentration of 0.32 was obtained. By comparing these results with the results shown in the examples above, it can be seen that the product of the present invention is excellent in storage stability and background discoloration. Comparative Example 2 In Example 2, 3 parts by weight of phloroglucin was used instead of the mixed coupler, and the dry weight was 1.8 g/m ²
A product was obtained and tested in the same manner except that. In the printing test, the print density was 0.98, and the background density was 0.98.
A storage test at 40℃ and 90% concentration (RH) resulted in a skin density of 0.25, and a storage test at 60℃ and dry conditions resulted in a skin density of 0.32. Ta. In addition, in a long-term storage test for one month, a skin concentration of 0.34 was obtained. Comparative Example 3 In Example 1, the amount of stearamide in liquid A of Example 1 was changed to 2.0 parts by weight, and the dry weight was changed to 1.5 g/
A product was obtained and tested in the same manner as in Example ¹ , except that the amount of N-stearylbenzamide in liquid B was 5.0 parts by weight and the dry weight was 1.6 g/m ² . In the printing test, a print density of 0.70 and a background density of 0.11 were obtained at 40℃ and humidity (RH).
In the storage test under 90% conditions, a skin density of 0.16 was obtained, and in the storage test under dry conditions at 60°C, a skin density of 0.21 was obtained. In addition, a one-month long-term storage test showed that the skin concentration was 0.13. From this result, it can be seen that when the amount of the thermofusible substance is small, the desired color development cannot be obtained. Comparative Example 4 In Example 1, instead of naphthol AS -
A product was obtained and tested in the same manner except that sodium 1-hydroxynaphthalene-4-sulfonate-8-N-isopropylsulfonamide, which does not have a CONHR ¹ bond, was used. In the printing test, the print density was 0.87, the background density was 0.14, and 40
A storage test at 90% humidity (RH) at 60°C yielded a skin density of 0.36, and a storage test at 60°C and dry conditions yielded a skin density of 0.42. In addition, a one-month long-term storage test showed that the skin concentration was 0.24. From this result, it can be seen that when the naphthol derivative specified in the present invention is not used, the product is inferior to the product of the present invention in terms of storage stability and skin fading. Comparative Example 5 In Example 1, 4-benzoylamino-
A product was obtained and tested in the same manner except that 2,5-diethoxyacetoacetanilide, which does not have an R ² CONH bond, was used in place of 2,5-diethoxyacetoacetanilide. In the printing test, a print density of 0.82 and background density of 0.15 were obtained, and in the storage test at 40℃ and 90% humidity (RH), a background density of 0.42 was obtained, and in the storage test at 60℃ and dry conditions. The result was that the skin density was 0.38. In addition, a one-month long-term storage test showed that the skin concentration was 0.32. from this result,
It can be seen that when the anilide compound specified in the present invention is not used, the product is inferior to the product of the present invention in terms of storage stability and skin fading.

Claims (1)

[Scope of Claims] 1. A diazo-based heat-sensitive recording material comprising a heat-sensitive coloring layer containing a diazo compound, a coupler, and a thermofusible substance, in which the coupler has the general formula (wherein, X is hydrogen, halogen, alkoxy or sulfonic acid group, R ¹ is aromatic group or alicyclic group,
n is 0 or 1) and a naphthol derivative represented by the general formula (In the formula, X ₁ and X ₂ are hydrogen, halogen, alkyl,
alkoxy or aryloxy, ^R2 is an aromatic group or alicyclic group, and Y is a cyano group or an acyl group), and the thermofusible material A diazo-based heat-sensitive recording material characterized in that the following is used in an amount of 5 to 30 parts by weight per 1 part by weight of a diazo compound.