JPH0464876B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a heat-sensitive recording material, and particularly to a heat-sensitive recording material that can be photofixed. That is, the present invention
When recorded with a heat head at a certain temperature, it develops a color,
The present invention relates to a diazo-based heat-sensitive recording material which loses its ability to develop color in non-printed areas when it is further irradiated with light, and which does not recolor when heat is applied again. [Prior Art] Thermosensitive recording materials are used as copy paper for books, documents, etc., as well as output recording paper for electronic computers, facsimile machines, medical measuring instruments, etc., as well as thermal recording magnetic ticket paper and thermal recording labels. It is also used as paper. In addition, thermosensitive recording materials can be used to record securities, gift certificates, admission tickets, etc. by taking advantage of the ease of automatic recording.
It is also being considered for use as paper for creating certificates, slips, etc. However, for such uses, heat-sensitive recording materials must be able to be fixed in order to obtain high recording reliability. It won't happen. 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 have not yet been satisfactory in terms of thermal response to thermal heads and long-term storage stability. In particular, in fields such as facsimile, high-speed recording performance (high-speed color development) is strongly required to reduce information transmission costs, but conventional diazo-based products
These requirements have not yet been fully satisfied. By the way, in conventional diazo photosensitive paper, when carrying out a color reaction, it was possible to use aqueous ammonia or alkaline aqueous solution as a developer, and to adopt conditions that would allow a sufficient color reaction to occur, and the color reaction could also be caused by heating. It was possible to supply a sufficient amount of heat even when the process was carried out. Therefore, in the case of diazo-sensitive paper, no special measures were required to cause the color reaction to occur at high speed. However, in the case of a heat-sensitive recording material that performs a coloring reaction with a small amount of thermal energy, such as a thermal head or a thermal pen, which is the object of the present invention, an image forming means such as that used in the case of diazo-sensitive paper may not be used. Therefore, various measures are required to efficiently cause the coloring reaction by using less thermal energy. [Purpose] The present inventors have conducted intensive research to develop a diazo-based heat-sensitive recording material that has high color development and excellent long-term storage stability, unlike the previously proposed diazo-based heat-sensitive recording materials.As a result, the present invention has been developed. I have come to complete it. [Structure] That is, according to the present invention, in a diazo thermosensitive recording material having a thermosensitive coloring layer having a laminated structure of a diazo layer and a coupler layer, the layer forming the lower layer of the diazo layer and the coupler layer is provides a diazo thermosensitive recording material characterized in that it contains a water-insoluble binder and at least one of the diazo layer and the coupler layer contains a biguanidine compound or an acid salt thereof. The biguanidine compound used in the present invention is typically represented by the following general formula. In the above formula, R ₁ to _{R 6} are hydrogen, alkyl, cycloalkyl, hydroxy, alkoxy, aromatic group,
Or represents a heterocyclic group. In this case, the alkyl includes lower or higher alkyl, and usually has 1 to 8 carbon atoms, the cycloalkyl is generally cyclohexyl, and the heterocyclic group includes nitrogen, oxygen, There are various groups containing heteroatoms such as sulfur, and aromatic groups include aryl, aralkyl, and substituted forms thereof;
Preferably, for example, those represented by the following formula are mentioned.

【formula】

【formula】

[Formula] (In the formula, R is a substituent such as alkyl, alkoxy, halogen, nitro group, amino group, etc.) Furthermore, in the above general formula, R ₁ and R ₂ or R ₅
R ₆ can each be linked to form a ring,
For example, the following cyclic groups can be formed.

【formula】

[Formula] The biguanidine compound can be used as an acid salt, and in this case, the acid salt is:
Examples include inorganic acid salts such as sulfuric acid, hydrochloric acid, carbonic acid, and phosphoric acid, and organic acid salts such as citric acid, tartaric acid, and oxalic acid. Next, specific examples of biguanidine compounds are shown below. The biguanidine compound used in the present invention is added to the diazo layer and/or the coupler layer, but this addition significantly accelerates the thermal coloring reaction, although the long-term shelf life of the product is impaired. The reason for this is as follows. That is, this is because the biguanidine compound exhibits strong basicity. However, when used in the layered structure of the present invention, it becomes possible to significantly accelerate the thermochromic reaction without impairing the long-term shelf life of the product. The biguanidine compound can also be contained in other parts of the coloring system, such as the overcoat layer and the undercoat layer. In the heat-sensitive recording material of the present invention, the lamination order of the diazo layer and the coupler layer is arbitrary, but the layer forming the lower layer preferably contains a water-insoluble binder together with a thermofusible substance. With this configuration, the lower layer becomes hydrophobic.
The biguanidine compound added to the diazo layer and/or coupler layer is:
It is used in a proportion of 0.5 to 10 parts by weight, preferably 1 to 10 parts by weight. As the diazo compound and coupler used in the present invention, those commonly used for diazo photosensitive paper are applicable, and examples thereof include those shown below. Diazo compound: 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

〔effect〕

The heat-sensitive recording material of the present invention can be advantageously applied in various heat-sensitive recording fields, particularly as output recording paper for facsimile machines and electronic computers that require high-speed recording.Moreover, in the case of the present invention, the surface Characters and images recorded on the recording medium can be fixed by forming the image by heating and then decomposing the unreacted diazo compound with light and heat. Furthermore, the heat-sensitive recording material of the present invention can be applied to recording necessary information on securities, gift certificates, admission tickets, certificates, slips, etc., and for creating them, by taking advantage of its fixing properties. Moreover, since the heat-sensitive recording material of the present invention has the above-mentioned special layer structure, it has extremely excellent long-term storage stability and thermal color development. [Example] Next, the present invention will be explained in more detail with reference to Examples. Examples 1 to 3 (Liquid A) 5 parts by weight Stearamide 20 〃 Styrene-acrylic copolymer 40 parts by weight Water 35 〃 (Liquid B) 5 parts by weight N-stearylbenzamide 15 〃 Vinyl chloride-vinyl acetate copolymer 20 〃 MEK (methyl ethyl ketone) 60 〃 (Liquid C) Naphthol AS 10 parts by weight Zinc stearate 20 〃 Vinylidene chloride-acrylic copolymer 40 〃 Water 30 (Liquid D) Phloroglucin 10 parts by weight Calcium carbonate (light) 20 Polyvinyl alcohol 10 10 〃 Water 50 parts by weight (E liquid) Sodium 2,3-dihydroxynaphthalene-6-sulfonate 10 parts by weight 10 〃 Silica (Thyroid 244) 10 〃 Methylcellulose 10 〃 Water 60 〃 (F liquid) 5 parts by weight 5 Silica (Thyroid 65) 10 Polyvinyl alcohol 5 Water 75 (Liquid G) A liquid obtained by removing the biguanidine compound from (Liquid D). (Solution H) A solution in which urea is used instead of the biguanidine compound of (Solution E). (Liquid I) A liquid obtained by removing the biguanidine compound from (Liquid F). (Solution J) 1,3 instead of the biguanidine compound of (Solution D)
-Liquid using diphenylguanidine The above composition was ground for 24 hours using a ball mill.
Dispersion liquids A to J were prepared by dispersion.

[Table] Shown in Table-1 above, Examples 1 to 3, Comparative Examples 1 to
Apply each coating solution according to step 4 on the surface of high-quality paper (approximately 50 g/m ² ) and dry to form a heat-sensitive layer with an adhesion amount of 2 to 3 g (solid content) for each layer, and then calender to smooth the surface. A heat-sensitive recording material was obtained which was heated for 500 seconds. After printing the heat-sensitive recording material obtained in the above manner in G-mode using RIFAX 3300 (manufactured by Ricoh Co., Ltd.),
Ricoh] was used to fully expose and fix the image. Next, Table 2 shows a quality comparison of Examples 1 to 3 and Comparative Examples 1 to 4.

【table】

[Table] From the results shown in Table 2 above, it can be seen that the products of the present invention have significantly improved thermal coloring properties without impairing storage stability or background density.

Claims (1)

[Claims] 1. In a diazo heat-sensitive recording material having a heat-sensitive coloring layer having a laminated structure of a diazo layer and a coupler layer, the layer forming the lower layer of the diazo layer and coupler layer contains a water-insoluble binder, and A diazo heat-sensitive recording material, characterized in that at least one of the layer and the coupler layer contains a biguanidine compound or an acid salt thereof.