JPS62142686A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a recording material having excellent preservation stability before printing and fixing and favorable recording sensitivity, by incorporating an amide compound having a melting point of 70-180 deg.C in a recording layer of a photo-fixable type thermal recording material. CONSTITUTION:An amide compound of the formula which has a melting point of 70-180 deg.C is incorporated in a recording layer of a photo-fixable type thermal recording material, the recording layer comprising microcapsules containing a diazonium compound therein, a coupler compound and a compound providing a basic atmosphere when being melted by heating. The amide compound may be, for example, acetanilide, alpha-acetonaphthalide or o-acetotoluidide. With this arrangement, a thermal recording material can be obtained which has excellent recording sensitivity and excellent preservation stability.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention relates to a photo-fixable heat-sensitive recording medium, and particularly to a photo-fixable heat-sensitive recording medium that has excellent recording storage stability before recording and also has good recording sensitivity. It is related to.

``Prior Art'' Conventionally, a recorded image was obtained by making use of the coloring reaction between a basic colorless dye and a coloring agent that can change color when it comes into contact with the dye, and bringing both photochromic substances into contact with each other using heat. Thermosensitive recording media are well known.

Since such a thermal recording medium has a structure in which a recorded image is obtained by heat, there is a defect that if the heat source is mistakenly brought close even after applying heat and recording, the entire heat source will develop color, making the necessary record unreadable. have. Therefore, it has been difficult to apply it to important records that require preservation.

Therefore, as a fixable heat-sensitive recording material, a diazo-based heat-sensitive recording material that utilizes a color-forming reaction between a diazonium compound and a coupler is being developed.

Generally, in a diazo thermosensitive recording material, a diazonium compound and a coupler are dispersed in the recording layer in the form of discontinuous particles, and a coloring aid that generates alkali upon heating is used in combination to form a recorded image. The structure is such that unreacted diazonium compounds are then decomposed by light irradiation to stop color development.

However, such recording media have a strong tendency to cause background fogging (unnecessary coloring phenomenon) due to pre-coupling before printing and fixing, so improvements are desired, and various improvement methods have been proposed. For example, a method using a highly hydrophobic guanidine derivative as a basic compound (Japanese Unexamined Patent Publication No. 57
-45094, JP-A-57-125091), a method using a water-insoluble diazonium compound (JP-A-58
55290), and a method of microencapsulating one or both of diazonium compounds, couplers, and basic compounds (Japanese Patent Application Laid-Open No. 190886/1986).

However, the recording sensitivity of the heat-sensitive recording materials obtained by these improved methods decreases due to improvements in pre-coupling before printing and fixing, making it difficult to apply to high-speed recording devices. At present, a photofixable thermosensitive recording material that satisfies both properties and recording sensitivity has not yet been obtained.

``Problems to be Solved by the Invention'' The purpose of the present invention is to overcome the above-mentioned difficulties in photofixing type thermal recording materials, to provide excellent storage stability of the recording material before printing and fixing, and to improve recording sensitivity. The objective is to provide a good recording medium.

"Means for Solving the Problems" The present invention provides a photofixable thermosensitive recording material provided with a recording layer containing a microcapsule containing a diazonium compound, a coupler compound, and a compound that exhibits a basic atmosphere when thermally melted. , the recording layer further contains a melting point of 70 to 180°C.
This is a heat-sensitive recording material characterized by containing an amide compound represented by the following general formula (T).

R+ CN R2(I) H [In the formula, R1 is a C1 to C4 alkyl group; represents an aryl group or aralkyl group that may be substituted with a halogen atom or a CI"" Ca alkyl group, and R2 is a hydrogen atom ; Represents an aryl group or aralkyl group which may be substituted with a halogen atom, a C, to C4 alkyl group, or a phenyl group. However, at least one of R1 and R2 represents the above-mentioned aryl group or aralkyl group. [Function] Specific examples of the amide compound represented by the general formula [I] used in the present invention include the following compounds, but are not limited thereto.

Acetanilide, α-acetonaphthalide, 0-acetotoluiside, p-acetotoluiside, p-bromoacetanilide, p-phenylacetanilide, β-acetonaphthalide, benzamide, α-phenylacetamide, benzanilide, 0-benztoluiside, m-benztoluiside, p -benztoluicide, m-toluic acid anilide, p-toluic acid anilide, β-naphthoic acid anilide, 2-chlorobenzanilide, 2'-chlorobenzanilide, 'l'-tert-butylbenzanilide, N
-benzylbenzanilide, N-phenethylbenzamide, 4'-propylbenzanilide, 2-phenylacetanilide and the like.

As mentioned above, the amide compound used in the present invention is selectively a compound having a specific melting point of 70 to 180°C, and a compound having a melting point outside of this range cannot achieve the desired effect of the present invention. I can't do that.

The amount of these compounds used is diazonium compound 1
It is desirable to adjust the amount in the range of 0.5 to 15 parts by weight, more preferably 1.0 to 10 parts by weight.

The microcapsules encapsulating the diazonium compound used in the present invention can be prepared by various known methods, but generally, the core material containing the diazonium compound is emulsified and dispersed in an aqueous medium, and the resulting core material is oiled. It is prepared by a method that forms a polymeric material film around the droplet.

Specific examples of polymeric substances include polyurethane, polyurea, polyamide, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene/methacrylate copolymer, styrene/acrylate copolymer, gelatin, polyvinyl alcohol, etc. However, polyurethane and polyurea films are particularly preferably used.

For example, microcapsules whose walls are made of polyurethane,
A polyvalent isocyanate and a polyol that reacts with it to form a wall film are mixed into the core material to be encapsulated, emulsified and dispersed in an aqueous medium in which a protective colloid material such as polyvinyl alcohol is dissolved, and the liquid temperature is raised. , produced by a polymer formation reaction at the oil droplet interface. In addition,
The particle size of the microcapsules is desirably adjusted within the range of about 0.1 to 10 μm in consideration of the recording sensitivity and the quality of the recorded image obtained.

Specific examples of core substances include phosphate esters such as tricresyl phosphate and octyl diphenyl phosphate, phthalate esters such as dibutyl phthalate and dioctyl phthalate, carboxylic acid esters such as butyl oleate, various fatty acid amides, and diethylene glycol diphthalate. Examples include benzoate, alkylated biphenyls such as isopropylbiphenyl, chlorinated paraffins, but are not limited to these.

Various materials are known for diazonium compounds to be encapsulated in microcapsules, such as p-N,
N-dimethylaminobenzenediazonium, 4-morpholino-2,5-dibutoxybenzenediazonium, 4-
Morpholino-2,5-diisopropoxybenzenediazonium, 4-(4'-methoxybenzoylamino)-2
, 5-jethoxybenzenediazonium, 4-morpholinobenzenediazonium, 4-pyrrolidino-3-methylbenzenediazonium, p-1'J-ethyl-N-hydroxyethylaniline diazonium, 4-benzamide-2,5-jethoxybenzene Diazonium, 2-N,
Examples include tetraphenyl boron salts such as N-diethyl-m-t-luidine diazonium and 6-morpholino-m-toluidine diazonium, tetrafluoroboron salts, and phosphorus hexafluoride salts, among which phosphorus hexafluoride salts are used. It is particularly preferably used.

These diazonium compounds are generally used by being dissolved or mixed in an organic solvent as a core substance at a concentration of 1 to 50% by weight.

The coupler compound used in combination with the thus prepared microcapsules containing a diazonium compound is a material that forms a dye through a coupling reaction with the diazonium compound in a basic atmosphere, and specific examples include redulcinol, catechol, and phloroglucin. , α-naphthol,
1,5-dihyF loxinaphthalene, 2,5-dimethyl-
4-morpholinomethylphenol, sodium 1-hydroxynaphthalene-4-sulfonate, N-(3-morpholinopropyl)-3-hydroxy-2-naphthamide,
2-hydroxy-3-(β-hydroxyethylamide carbonyl)naphthalene, 2-hydroxynaphthalene-3
-carbonylgetanolamine, sodium 2-hydroxynaphthalene-3,6-disulfonate, acetoacetanilide, 3-methyl-5-pyrazolone, l-phenyl-3-methyl-5-pyrazolone, 2-hydroxy-3
naphthoic acid hydroxyethylamide, 2-hydroxy-
3-naphthoic acid anilide, 2-hydroxy-3-naphthoic acid-α-naphthalide, 2-hydroxy-3-naphthoic acid-β
-naphthalide, 2-hydroxy-3naphthoic acid-4'-
Chloranilide, 2-hydroxy-3-naphthoic acid-4'
-Fluoroanilide, 2-hydroxy-3-naphthoic acid-2
',6'-dichloroanilide, 2-hydroxy-3naphthoic acid-2',6'-dichloroanilide, 4,4'-di-0-acetoacetotoluiside, benzoylacetanilide, etc., but are of course limited to these. It is also possible to use two or more types together.

The amount of the coupler compound to be incorporated into the recording layer cannot be determined unconditionally as it varies depending on the type of compound used, but it is generally 0.1 to 1 part by weight per 1 part by weight of the diazonium compound.
It is blended in an amount of about 10 parts by weight, more preferably about 0.3 to 5 parts by weight.

The compound used in the present invention that exhibits a basic atmosphere when melted by heat is not particularly limited as long as it generates alkali when heated, and various heat-melting basic compounds are preferably used, but in particular Amidine derivatives represented by the following general formula (n) or (I[I), in combination with various materials of the present invention, have particularly excellent recording storage stability before recording, as well as optical fixing with extremely good recording sensitivity. This method is most preferably used because a type heat-sensitive recording material can be obtained.

R3-C-NH-R4(II) -R5 [wherein, R3 represents a C2 to C1° linear or branched alkyl group; a C7 to CI4 aralkyl group; a phenyl group or a naphthyl group; , R1 represents a C7 to CI4 linear or branched alkylene group, R4, Rs, Rh,
R8, Rq, R+. represents a phenyl group or a naphthyl group. In addition, the Hensen ring included in the formula is a halogen atom, C
lNC4 alkyl group, C, -C, alkoxyl group,
It may be substituted with a phenyl group or a hensyl group. ]
Specific examples of the amidine derivatives represented by the above formula (n) include N,N'-diphenylacetamidine,
N,N'-bis(p-tolyl)acetamidine, N,N
'-bis(p-chlorophenyl)acetamidine, N,
N'-diphenylpropionamidine, N,N'-diphenylcaprylamidine, N,N'-Schiff-Uniru2
-naphthyl (1) acetamidine, 3. N,N'-triphenylpropionamidine, N,N'-diphenylbenzamidine, N,N'-bis(p-tolyl)benzamidine, N,N'-diphenyl-p-anisamidine, N,N'- Bis(p-chlorophenyl)benzamidine, N-phenyl-N'-p-tolylbenzamidine,
Examples include N,N'-bis<p-methoxyphenyl)benzamidine, but are not limited thereto.

Further, specific examples of the amidine derivative represented by the above general formula (I[[) include N, N', N''.

N-tetraphenylhexanecyamidine, N,N'N"
, Nμ tetraphenyldecanecyamidine, N.

Examples include N', N'', N'-made tetrakis(p-tolyl)hebutanecyamidine, N, N', N'', N-ytrakis(p-chlorophenyl)octanecyamidine, etc.
Of course, it is not limited to these.

Moreover, two or more kinds of amidine derivatives represented by these general formulas (II) or (III) can also be used in combination.

The blending ratio of the heat-melting basic compound cannot be unconditionally determined as it varies depending on the type of compound used, but it is generally 1 to 3 parts by weight per 1 part by weight of the diazonium compound.
0 parts by weight, more preferably 5 to 15 parts by weight.

The coupler compound, the compound exhibiting a basic atmosphere when melted by heat, and the specific amide compound used in the present invention can be encapsulated and used in the same way as the diazonium compound, but when not encapsulated,
It is preferable to use a suitable agitating and pulverizing device such as a ball mill, sand grinder, attritor, etc. so that the particle size becomes 10 μm or less.

Thus, in the present invention, a heat-sensitive recording layer containing at least one of the microcapsules containing a diazonium compound, a coupler compound, a compound that exhibits a basic atmosphere when melted by heat, and the above-mentioned specific ryomido compound is formed on a support. However, such a heat-sensitive recording layer is generally formed by preparing a coating solution containing the above-mentioned substances and coating it on a support.

The coating liquid contains sodium naphthalene sulfonate, sodium naphthalene disulfonate, sulfosalicylic acid,
Preservation improvers such as magnesium sulfate and zinc chloride, antioxidants such as thiourea, diphenylthiourea, and urea, acid stabilizers such as citric acid, malic acid, tartaric acid, phosphoric acid, and saponin, starch, casein, and gum arabic. , various water-soluble or water-dispersible adhesives such as polyvinyl alcohol, polyvinyl acetate emulsion, styrene-butadiene copolymer latex, silica, clay, barium sulfate, titanium oxide,
Pigments such as 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 paraffins, chlorinated paraffins, and naphthoic acids. Various auxiliary agents such as melting point depressants such as alkyl or aryl esters 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 a conventional method. For example, by using a suitable coating device such as an air knife coater, roll coater, blade coater, etc., it is possible to coat the diazonium compound at a dry weight of about 3 to 20 g/rd.
(approximately 0 g/rrr) and dried.

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 thermal recording medium, and then the entire surface is irradiated with ultraviolet light using a fluorescent lamp, a mercury lamp, etc., and the non-recorded portions are exposed. By decomposing unreacted diazonium compounds,
It is capable of fixing recorded images.

"Example" The present invention will be described in more detail with reference to Examples below, but it is of course not limited to these.

Further, unless otherwise specified, parts and % in the examples indicate parts by weight and % by weight, respectively.

Example I Preparation of Solution A 2 parts of 4-morpholino-2,5-dibutoxybenzenediazonium phosphorus hexafluoride salt and trimethylolpropane adduct of xylylene diisocyanate (trade name Takene) 1
1ON, manufactured by Narita Pharmaceutical), 10 parts of tricresyl phosphate
Dissolved in a mixed solvent of 0 parts and 10 parts of diptyl phthalate,
The resulting solution was diluted with a 6% aqueous solution of polyvinyl alcohol.
An emulsion having an average particle diameter of 1.8 μm was obtained by emulsifying and dispersing the particles in the same volume.

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 Liquid A.

Preparation of liquid B 2-hydroxy-3-naphthoic acid-0-)luidide
5 parts N,N'-diphenylbenzamidine 10 parts benzanilide
10 parts calcium carbonate
20 parts 100 parts of a 10% aqueous solution of polyvinyl alcohol The above composition was dispersed in a ball mill for 48 hours to prepare Solution B.

The coating liquid obtained by mixing 50 parts of the above dispersion A and 100 parts of the dispersion B was coated on 49 g/f high-quality paper using a wire bar so that the dry weight was 8 g/rrr, and dried to make a thermal recording. I got a body.

Example 2 B of Example 1? &N,N',N" instead of N,N'-diphenylbenzamidine in the preparation.

A thermosensitive recording material was obtained in the same manner as in Example 1 except that N-tetraphenylhexanecyamidine was used.

Example 3 B of Example 1? & In the preparation, N,N'-di(p-tolyl)acetamidine was used instead of N,N'-diphenylbenzamidine, and phenylacetanilide was used instead of benzanilide, but in the same manner as in Example 1. A thermosensitive recording medium was obtained.

Example 4 In the preparation of lacquer A in Example 1, 4-morpholino-2,5
A thermosensitive recording material was obtained in the same manner as in Example 1 except that p-N,N-diethylaminobenzenediazonium phosphorus hexafluoride salt was used instead of dibutoxybenzenediazonium phosphorus hexafluoride salt.

Examples 5 to 6 A thermosensitive recording material was obtained in the same manner as in Example 1 except that O-methylphenylacetanilide and acetanilide were used in place of benzanilide in the preparation of liquid B in Example 1.

Comparative Example 1 A thermosensitive recording material was obtained in the same manner as in Example 1 except that benzanilide was not blended in the preparation of liquid B in Example 1.

Comparative Examples 2 to 3 A thermosensitive recording material was obtained in the same manner as in Example 1, except that stearamide and di-4-methylphenyl carbonate were used in place of benzanilide in the preparation of liquid B in Example 1.

Comparative tests were conducted on the recording sensitivity and storage stability of the nine types of heat-sensitive recording bodies thus obtained. That is, regarding recording sensitivity, thermal recording is performed using a G type practical facsimile (UF-2, manufactured by Matsushita Densen), the image is fixed by exposure to ultraviolet light, and the color density is measured using a Macbeth densitometer (yellow filter). ) was measured. In addition, regarding the storage stability of the recording material, the thermal recording material immediately after coating and the storage stability at 40℃
The capri densities of the recording layers of the heat-sensitive recording bodies after being left under the condition of -90% RH for 24 hours were measured using a Macbeth densitometer (yellow filter) and compared.

The test results obtained are shown in Table 1.

Table 1 "Effects" As is clear from the results in Table 1, the heat-sensitive recording bodies obtained in each example of the present invention all have excellent recording sensitivity and are stable in storage. She had excellent sex.

Although the reason why such excellent effects are obtained is not necessarily clear, the present inventors estimate that the microcapsules containing the diazonium compound and the specific amide compound exhibit an excellent synergistic effect, As a result, it is presumed that the storage stability and recording sensitivity of the recording medium can be significantly improved. That is, the above-mentioned specific amide compound not only lowers the melting point of coupler compounds and compounds that exhibit a basic atmosphere when heated, but also significantly improves the permeability of the coupler compound through the capsule wall membrane when heated, and as a result, the capsule It is thought that this promotes the coupling reaction within, contributing to improved recording sensitivity.

Claims (2)

[Claims] (1) In a photofixable thermosensitive recording material provided with a recording layer containing a microcapsule containing a diazonium compound, a coupler compound, and a compound that exhibits a basic atmosphere when melted, the recording layer further includes a melting point of 70 to 70. A heat-sensitive recording material containing an amide compound represented by the following general formula [I] at 180°C. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [I] [In the formula, R_1 is a C_1 to C_4 alkyl group; represents an aryl group or aralkyl group that may be substituted with a halogen atom or a C_1 to C_4 alkyl group. , R_2 is a hydrogen atom; a halogen atom,
Indicates an aryl group or aralkyl group which may be substituted with a C_1 to C_4 alkyl group or phenyl group. However, at least one of R_1 and R_2 represents the above-mentioned aryl group or aralkyl group. ] (2) The heat-sensitive recording material according to claim (1), wherein the compound exhibiting a basic atmosphere during thermal melting is an amidine derivative represented by the following general formula [II] or [III]. ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [II] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [III] [In the formula, R_3 is a linear or branched alkyl group of C_1 to C_1_0; C_7 to Aralkyl group of C_1_4; represents phenyl group or naphthyl group, R_7 is C_1
~C_1_2 represents a linear or branched alkylene group, R_4, R_5, R_6, R_8, R_9, R_1
_0 represents a phenyl group or a naphthyl group. In addition, the benzene ring contained in the formula is a halogen atom, a C_1 to C_4 alkyl group, a C_1 to C_4
may be substituted with an alkoxyl group, phenyl group or benzyl group. ]