JPH0469554B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention relates to a photo-fixable heat-sensitive recording material, and more particularly to a black-colored light-fixable heat-sensitive recording material that has excellent recording storage stability before recording. ``Prior Art'' Conventionally, a recorded image has been obtained by making use of the coloring reaction between a basic colorless dye and a coloring agent that can develop a color when it comes into contact with the dye, and bringing both coloring substances into contact with each other using heat. Thermosensitive recording media made of this type are well known. Since such a thermal recording medium is structured to obtain a recorded image using heat, if the heat source is mistakenly brought close to the recording medium even after applying heat and recording, the entire heated area will develop color.
It has the defect that necessary records become illegible. Therefore, it has been difficult to apply it to important records that require preservation. Therefore, as a fixable heat-sensitive recording material, development of a diazo-based heat-sensitive recording material that utilizes a color-forming reaction between a diazonium compound and a coupler compound is underway. Generally, in a diazo-based heat-sensitive recording material, a diazonium compound and a coupler compound are dispersed in the recording layer in the form of discontinuous particles, and a recorded image is created using a coloring aid that generates alkali when heated. The structure is such that the unreacted diazonium compound is formed and then irradiated with light to decompose the unreacted diazonium compound to stop color development. However, in such a thermal recording medium, printing,
There is a strong tendency for background fogging (unnecessary coloring phenomenon) to occur due to pre-cutting before fixing, and this tendency is particularly noticeable with black coloring recording media.
Improvements are strongly desired. "Problems to be Solved by the Invention" The purpose of the present invention is to improve the above-mentioned difficulties in light-fixing type heat-sensitive recording materials, and to create a black coloring material with excellent storage stability before printing and fixing. An object of the present invention is to provide a thermosensitive recording medium. "Means for Solving the Problems" In view of the above-mentioned current situation, the inventors of the present invention have conducted intensive studies on background fog, especially in black-coloring photofixing type thermal recording materials. It has been found that background fogging is more likely to occur because phloroglucin is often used as a coupler compound or a naphthol coupler compound and acetoacetanilide are used in combination to obtain black coloring. That is, since the above-mentioned coupler compounds have water solubility, when they are left under particularly high humidity conditions or when water is attached to them, they dissolve and pre-couple with the diazonium compound. Based on this knowledge, we conducted further intensive research on coupler compounds and found that when two or more specific coupler compounds are used in combination, there is almost no background fogging even in black-coloring heat-sensitive recording materials.
The present invention was achieved by discovering that the storage stability of a recording medium before printing and fixing is dramatically improved. The present invention relates to a light-fixing heat-sensitive recording material provided with a recording layer containing a diazonium compound, a coupler compound, and a compound that exhibits basicity when melted by heat. This is a heat-sensitive recording material characterized by containing at least one of the following. [In the formula, R ₁ , R ₂ , R ₃ are each a hydrogen atom, C _1-4
represents an alkyl group, a _C1-4 alkoxyl group, or a halogen atom. Note that R ₁ to _{R 3} may be bonded to each other to form an aromatic ring. ] [In the formula, R ₄ and R ₅ each represent a hydrogen atom, a C _1-4 alkyl group, a C _1-4 alkoxyl group, or a halogen atom. X is a single bond, a linear or branched C _1-4 alkylene group, a phenylene group, -O-, -S
-, _-SO2- , -CONH-, or a combination of two or more of these groups. ] "Function" Specific examples of the coupler compound represented by the general formula [ ] used in the present invention include, for example, the following compounds, but are of course not limited to these. 2-Hydroxy-3-naphthoic acid anilide, 2
-Hydroxy-3-naphthoic acid-4'-chloroanilide, 2-hydroxy-3-naphthoic acid-o-toluidide, 2-hydroxy-3-naphthoic acid-α
-naphthalide, 2-hydroxy-3-naphthoic acid-o-methoxyanilide, 2-hydroxy-3-
Naphthoic acid-o-ethoxyanilide, 2-hydroxy-3-naphthoic acid-p-n-butylanilide, 2-hydroxy-3-naphthoic acid-2',6'-
Dichloroanilide, 2-hydroxy-3-naphthoic acid-2',6'-difluoroanilide, 2-hydroxy-3-naphthoic acid-2',4',6'-trichloroanilide, 2-hydroxy-3-naphthoic acid-2',6'-difluoroanilide acid-2′,
4',6'-trimethylanilide, 2-hydroxy-
3-naphthoic acid-2'-methyl-4'-chloroanilide, 2-hydroxy-3-naphthoic acid-4'-chloro-2',5'-dimethoxyanilide, etc. Further, specific examples of the coupler compound represented by the general formula [] include the following compounds, but are of course not limited to these.
4,4'-bis(benzoylacetylamino)diphenyl 4,4'-bis(benzoylacetylamino)-3,
3′-dimethoxydiphenyl 4,4'-bis(benzoylacetylamino)-3,
3'-dimethyldiphenyl 4,4'-bis(benzoylacetylamino)diphenylmethane 4,4'-bis(benzoylacetylamino)-3,
3′-dichlorodiphenylmethane 4,4'-bis(benzoylacetylamino)diphenyl ether 2,2'-bis(benzoylacetylamino)diphenyl disulfide 4,4'-bis[(4-benzoylacetylamino)
Phenoxy] diphenyl sulfone 4,4'-bis(benzoylacetylamino)benzanilide Incidentally, two or more types of the coupler compounds represented by the above general formulas [] and [] can also be used in combination. In the present invention, the proportion of the compound represented by the general formula [] and the compound represented by the general formula [] is determined by the types of diazonium compounds and compounds that show basicity when heated, which together with the coupler compound constitute the recording layer. It should be selected appropriately depending on the
In general, it is desirable to use them together in a molar ratio of 1:0.1 to 0.5 in order to obtain a pure black tone recorded image. Furthermore, the amount of such a specific coupler compound to be incorporated into the recording layer cannot be determined unconditionally as it varies depending on the type of coupler compound used, but it is generally 0.1 to 10 parts by weight per 1 part by weight of the diazonium compound. It is desirable to mix about 1 part. Various materials are known as the diazonium compound used in combination with the coupler compound of the present invention, such as p-N,N-dimethylaminobenzenediazonium, 4-morpholino-2,5-dibutoxybenzenediazonium, -morpholino-
2,5-diisopropoxybenzenediazonium, 4-(4'-methoxybenzoylamino)-2,
5-diethoxybenzenediazonium, 4-morpholinobenzenediazonium, 4-pyrrolidino-
3-methylbenzenediazonium, p-N-ethyl-N-hydroxyethylanilinediazonium, 4-benzamido-2,5-diethoxybenzenediazonium, 2-N,N-diethyl-m-
Toluidine diazonium, 6-morpholino-m-
Examples include double salts of chlorides such as toluidine diazonium and zinc chloride, tetraphenyl boron salts, boron tetrafluoride salts, phosphorous hexafluoride salts, and the like. Note that the diazonium compound can also be used by being encapsulated in microcapsules formed by a polymer film. The compound used in the present invention that exhibits a basic atmosphere when melted is not particularly limited as long as it generates alkali when heated, and various heat-melting basic compounds are preferably used. In particular, the amidine derivatives represented by the following general formula [] or [], in combination with the various materials of the present invention, can be used as light-fixing type materials that have particularly excellent recording storage stability before recording and extremely favorable recording sensitivity. It is most preferably used because a thermosensitive recording material can be obtained. [In the formula, R ₆ represents a C _1-10 linear or branched alkyl group, a C _7-14 aralkyl group, phenyl group, or naphthyl group, and R ₁₀ represents a C _1-12 straight-chain or branched alkyl group. Indicates a chain or branched alkylene group. _R7 , _R8 , _R9 ,
R ₁₁ , R ₁₂ and R ₁₃ each represent a phenyl group or a naphthyl group. Note that the benzene ring included in the formula may be substituted with a halogen atom, a _C1-4 alkyl group, a _C1-4 alkoxyl group, a phenyl group, or a benzyl group. ] Specific examples of amidine derivatives represented by the above general formula [] include N,N'-diphenylacetamidine, N,N'-bis(p-tolyl)acetamidine, N,N'-bis(p-tolyl)acetamidine, N,N'-bis(p-tolyl)acetamidine, -chlorophenyl)acetamidine, N,N'-diphenylpropionamidine, N,N'-diphenylcaprylamidine, N,N'-diphenyl-2-naphthyl(1)acetamidine, 3,N,N'-triphenyl enylpropionamidine, N,N'-diphenylbenzamidine, N,N'-bis(p-tolyl)benzamidine, N,N'-diphenyl-p-anisamidine, N,N'-bis(p-chlorophenyl) Benzamidine, N-phenyl-N'-p-
Examples include tolylbenzamidine, N,N'-bis(p-methoxyphenyl)benzamidine, and the like, but the present invention is not limited thereto. Further, as specific examples of the amidine derivatives represented by the above general formula [], for example, N, N', N'', N
-tetraphenylhexanediamidine, N,
N', N'', N-tetraphenyldecane diamidine, N, N', N'', N-tetrakis(p-tolyl)heptane diamidine, N, N', N'', N-
Examples include tetrakis(p-chlorophenyl)octanediamidine, but are not limited thereto. Moreover, two or more kinds of amidine derivatives represented by these general formulas [] or [] can also be used in combination. Note that the blending ratio of the heat-melting basic compound cannot be unconditionally determined because it varies depending on the type of compound used, but in general, the blending ratio of the diazonium compound 1
1 to 30 parts by weight, more preferably 5 parts by weight
~15 parts by weight is blended. Coupler compounds used in the present invention,
Compounds that exhibit a basic atmosphere when hot melted and diazonium compounds are preferably used after being treated to a particle size of 10 μm or less using a suitable stirring and pulverizing device such as a ball mill, sand grinder, or attritor. Thus, in the present invention, a heat-sensitive recording layer containing at least one of a diazonium compound, the above-mentioned specific coupler compound, and a compound that exhibits a basic atmosphere upon thermal melting is formed on a support. The heat-sensitive recording layer is formed by preparing a coating solution containing the above-mentioned substances and coating it on a support. The coating liquid contains preservability improvers such as sodium naphthalene sulfonate, sodium naphthalene disulfonate, sulfosalicylic acid, magnesium sulfate, zinc chloride, thiourea, diphenylthiourea,
Antioxidants such as urea, acid stabilizers such as citric acid, malic acid, tartaric acid, phosphoric acid, saponin, starch, casein, gum arabic, polyvinyl alcohol, polyvinyl acetate emulsion, styrene-butadiene copolymer latex, etc. Various water-soluble or water-dispersible adhesives, silica, clay, barium sulfate,
Pigments such as titanium oxide and calcium carbonate, as well as animal and vegetable waxes, petroleum waxes, polyhydric alcohol esters of higher fatty acids, higher fatty acid amides, condensates of higher fatty acids and amines, synthetic paraffin, chlorinated paraffin, Various auxiliary agents such as a melting point depressant such as an alkyl or aryl ester of naphthoic acid are appropriately blended. The coating solution prepared in this way is coated on a suitable support such as paper, plastic film, synthetic paper, metal film, etc., but the coating method is not particularly limited and can be applied using any conventional method. Therefore, by using a suitable coating device such as an air knife coater, a roll coater, a blade coater, etc., a dry weight of about 3 to 20 g/m ² (at least the coating amount of the diazonium compound is 0.05 to 2.0 g/m ² It is coated and dried to a certain degree. In addition, in the recording medium of the present invention, a recorded image is formed using a thermal pen, a thermal head, etc. in the same way as a normal heat-sensitive recording medium, and then the entire surface is irradiated with ultraviolet light using a fluorescent light, mercury lamp, etc., to remove the non-recorded areas. By decomposing unreacted diazonium compounds, recorded images can be fixed. "Example" The present invention will be described in more detail with reference to Examples below, but it is of course not limited to these. In addition, unless otherwise specified, parts and percentages in examples are as follows:
Weight parts and weight % are shown, respectively. Example 1 Preparation of Solution A p-N,N-diethylaminobenzenediazonium tetraphenylboron 2 parts Calcium carbonate 50 parts 10% aqueous solution of polyvinyl alcohol 50 parts Water 100 parts The above composition was dispersed in a ball mill for 48 hours to prepare A.
A liquid was prepared. Preparation of Solution B 2-Hydroxy-3-naphthoic acid-2',6'-dichloroanilide 20 parts 4,4'-bis(benzoylacetylamino)diphenylmethane 5 parts 3,N,N'-triphenylpropionamidine
25 parts 20% aqueous dispersion of stearic acid amide 40 parts 10% aqueous solution of polyvinyl alcohol 50 parts The above composition was dispersed in a ball mill for 48 hours.
A liquid was prepared. Using a wire bar, add 49g of the above dispersion B/
Coat and dry to a dry weight of 4 g/m ² on a m ² high-quality paper, and then coat and dry dispersion A to a dry weight of 4 g/m ² on top of the coated layer. A thermosensitive recording medium was obtained. Example 2 Preparation of Solution A 4-morpholino-2,5-dibutoxybenzenediazonium phosphorus heptafusinide 2 parts Titanium oxide 50 parts 10% aqueous solution of polyvinyl alcohol 50 parts Water 100 parts The above composition was dispersed in a ball mill for 48 hours. TeA
A liquid was prepared. Preparation of Solution B 2-hydroxy-3-naphthoic acid-2'-methylanilide 20 parts 4,4'-bis[(4-benzoylacetylamino)
Phenoxy]diphenylsulfone 5 parts N,N'-diphenylbenzamidine 25 parts 20% aqueous dispersion of stearic acid amide 40 parts 10% aqueous solution of polyvinyl alcohol 50 parts The above composition was dispersed in a ball mill for 48 hours to obtain B.
A liquid was prepared. A thermosensitive recording material was obtained in the same manner as in Example 1 except that the above dispersions A and B were used. Example 3 Preparation of Solution A 2 parts of 4-morpholino-2,5-dibutoxybenzenediazonium phosphorus hexafluoride salt and 10 parts of a trimethylolpropane adduct of xylylene diisocyanate (trade name: Takenate 110N, manufactured by Takeda Pharmaceutical Co., Ltd.),
It was dissolved in a mixed solvent of 10 parts of tricresyl phosphate and 10 parts of dibutyl phthalate, and the resulting solution was emulsified and dispersed in 70 parts of a 6% aqueous solution of polyvinyl alcohol to obtain an emulsion with an average particle size of 1.8 μm. . 70 parts of water was added to the obtained emulsion and reacted at 60° C. for 3 hours to prepare a microcapsule dispersion containing a diazonium compound as Solution A. Preparation of Solution B 2-hydroxy-3-naphthoic acid alinide 3 parts 4,4'-bis(benzoylacetylamino) diphenyl ether 1 part N,N'-diphenylacetamidine 10 parts benzanilide 10 parts calcium carbonate 20 parts polyvinyl alcohol 100 parts of a 10% aqueous solution of B. Disperse the above composition in a ball mill for 48 hours.
A liquid was prepared. A coating liquid obtained by mixing 50 parts of the above dispersion A and 100 parts of the dispersion B was mixed with a wire bar at 49 g/m ²
The mixture was coated on high-quality paper and dried to a dry weight of 8 g/m ² to obtain a heat-sensitive recording material. Comparative Example 1 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the coupler compound in the preparation of liquid B was replaced with phloroglucin. Comparative Example 2 In the preparation of Solution B of Example 2, 4,4'-bis[(4-benzoylacetylamino)phenoxy]
A thermosensitive recording material was obtained in the same manner as in Example 2 except that diphenyl sulfone was replaced with acetanilide. Comparative Example 3 A thermosensitive recording material was obtained in the same manner as in Example 3 except that 4,4'-bis(benzoylacetylamino)diphenyl ether was replaced with acetoacetanilide in the preparation of liquid B in Example 3. Comparative tests were conducted on the color tone and storage stability of the six types of heat-sensitive recording bodies thus obtained. That is, regarding the recording sensitivity, thermal recording is performed using a G type practical facsimile (UF-2, manufactured by Matsushita Densen), and after the image is fixed by exposure to ultraviolet light, the color density is measured using a Macbeth densitometer (yellow filter). It was measured with In addition, regarding the storage stability of the recording material, the thermal recording material immediately after coating and the storage stability at 40℃
The fog densities of the recording layers of the thermosensitive recording bodies after being left under -90% RH conditions for 24 hours were measured using a Macbeth densitometer (yellow filter) and compared. The test results obtained are shown in Table 1.

[Table] "Effect" As is clear from the results in Table 1, the heat-sensitive recording materials obtained in each example of the present invention all developed a sufficient black color at a practical recording sensitivity. It had excellent storage stability.

Claims (1)

[Scope of Claims] 1. In a light-fixing heat-sensitive recording material provided with a recording layer containing a diazonium compound, a coupler compound, and a compound that exhibits basicity when melted by heat, the coupler compound is represented by the following general formulas [] and []. 1. A heat-sensitive recording material containing at least one of the compounds shown below. [In the formula, R ₁ , R ₂ , R ₃ are each a hydrogen atom, C _1-4
represents an alkyl group, a _C1-4 alkoxyl group, or a halogen atom. Note that R ₁ to _{R 3} may be bonded to each other to form an aromatic ring. ] [In the formula, R ₄ and R ₅ each represent a hydrogen atom, a C _1-4 alkyl group, a C _1-4 alkoxyl group, or a halogen atom. X is a single bond, a linear or branched C _1-4 alkylene group, a phenylene group, -O-, -S
-, _-SO2- , -CONH-, or a combination of two or more of these groups. ] 2 A compound that exhibits a basic atmosphere during thermal melting is
The heat-sensitive recording material according to claim 1, which is an amidine derivative represented by the following general formula [] or []. [In the formula, R ₆ represents a C _1-10 linear or branched alkyl group, a C _7-14 aralkyl group, phenyl group, or naphthyl group, and R ₁₀ represents a C _1-12 straight-chain or branched alkyl group. Indicates a chain or branched alkylene group. _R7 , _R8 , _R9 ,
R ₁₁ , R ₁₂ and R ₁₃ each represent a phenyl group or a naphthyl group. Note that the benzene ring included in the formula may be substituted with a halogen atom, a _C1-4 alkyl group, a _C1-4 alkoxyl group, a phenyl group, or a benzyl group. ]