JP3331383B2 - Thermal recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material,
More specifically, the present invention relates to a heat-sensitive recording material having excellent storage stability of a recorded image.

[0002]

2. Description of the Related Art Various recording materials have been proposed which utilize a color-forming reaction between a colorless or pale-colored leuco dye and a color developing agent upon contact with color by heat and pressure. One such heat-sensitive recording material does not require complicated processing such as development and fixing, and can be recorded in a short time with a relatively simple device, has less noise, and has advantages such as low cost. It is useful as various recording materials for electronic calculators, facsimile machines, ticket vending machines, label printers, recorders and the like.

As a color-forming dye used in a heat-sensitive recording material, for example, a colorless or light-colored leuco dye having a lactone, lactam or spiropyran ring is used, and as a developer, an organic acid, a phenolic substance or the like is conventionally used. ing. Thermosensitive recording materials using this leuco dye and a developer are widely used because of their high image density and high whiteness of the background.

On the other hand, as the demand for the thermosensitive recording system has increased in recent years, there has been an increasing demand for improvement in the preservability of recording chemicals, light, heat, and the like. ing. In order to cope with high storage stability of recorded images, high-reliability developers such as those disclosed in JP-A-58-82788 and JP-A-60-138 are used.
No. 52, etc., a phenol sulfone compound is disclosed in
A metal salt of benzoic acid as disclosed in Japanese Patent Application Laid-Open No. 1-47292 and a substituted salicylic acid compound have been proposed in Japanese Patent Application Laid-Open No. Sho 62-169681, and the like. However, it is not yet sufficient in terms of the fastness of parts to fats and oils, plasticizers, water and the like.

[0005] On the other hand, it has been proposed to provide various intermediate layers as means for improving recording sensitivity, and a method using various inorganic pigments, a method using non-foamable intermediate particles for the intermediate layer, and the like have been proposed. However, the recording materials proposed in these methods have disadvantages of insufficient color sensitivity and poor recording characteristics.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material which is excellent in storage stability of a recorded image and is suitable for a high-speed recording material.

[0007]

According to the present invention, there is provided a heat-sensitive recording material having a heat-sensitive coloring layer comprising, as a main component, a leuco dye and a developer which causes the leuco dye to develop color when heated. The following general formula (I) is used as a developer.
A heat-sensitive recording material characterized by using the compound represented by the formula:

Wherein R represents an alkyl group, an aralkyl group, or an aryl group, provided that the alkyl group may have an alkoxy group, an acyl group, an acyloxy group, a halogen atom, a nitro group, and an aralkyl group. , The aromatic ring of the aryl group may have an alkyl group, an alkoxy group, an acyl group, an acyloxy group, a halogen atom, or a nitro group.)
The heat-sensitive recording material is provided, comprising an intermediate layer between the support and the heat-sensitive coloring layer, the intermediate layer being mainly composed of plastic spherical hollow particles made of a thermoplastic resin.

The present inventors have conducted intensive studies on a heat-sensitive recording material which has solved the conventional drawbacks, has excellent storage stability of recorded images, and is particularly suitable for high-speed recording materials. By using the compound represented by the general formula (I) as a color developer that develops color upon heating, it has been found that the intended purpose can be achieved, and the present invention has been completed. In the general formula (I), the substituent represented by R is preferably an alkyl group or an aralkyl group, and the substituent of the alkyl group is preferably an alkoxy group or a halogen atom, and the substituent of the aralkyl group is an alkyl group. Alkoxy groups and halogen atoms are preferred.

In the following, general formula (I) used in the present invention will be described.
Specific examples of the compound represented by are shown in Table 1 below, but the present invention is not limited thereto.

[Table 1- (1)]

[Table 1- (2)]

The intermediate layer comprising the plastic hollow spherical particles of the present invention as a main component acts as a heat insulating layer to improve the sensitivity by the efficient activation of heat energy from a thermal head or the like. Is 2
10 to 10 μm and a hollow ratio of 90% or more,
Flexibility is further improved, adhesion to the head is improved, and dot reproducibility is improved. The hollow particles used in the present invention are made of a thermoplastic resin as a shell and contain air or other gas inside, are already hollow microparticles, and have an average particle diameter of 2 to 10 μm. Is used. When the average particle diameter (particle outer diameter) is smaller than 2 μm, there is a problem in production such as difficulty in obtaining an arbitrary hollow ratio. On the contrary, when the average particle diameter is larger than 10 μm,
Since the smoothness of the surface after coating and drying is reduced, the adhesion to the thermal head is reduced, and the effect of improving sensitivity is reduced. Therefore, it is preferable that such a particle distribution is such that the particle diameter is within the above-mentioned range and the distribution peak with a small variation is uniform. Further, the minute hollow particles used in the present invention preferably have a hollow ratio of 50% or more from the heat insulating effect,
More than 90% is more preferable. A material having a low hollow ratio has an insufficient heat insulating effect, so that thermal energy from the thermal head is released through the support to the outside of the thermosensitive recording material, and the sensitivity improving effect is poor. The hollow particles referred to herein are the ratio of the outer diameter to the inner diameter of the hollow particles and are represented by the following formula. Hollow ratio = (inner diameter of hollow particle) / (outer diameter of hollow particle) × 100

The hollow microparticles used in the present invention have a shell of a thermoplastic resin as described above, and the resin is preferably a copolymer resin mainly containing vinylidene chloride and acrylonitrile. In the present invention, an inorganic or / and organic pigment is optionally used for the intermediate layer. In this case, the pigment may have an oil absorption of 30 ml.
/ 100 g or more, preferably 80 ml / 100 g or more. As these inorganic and / or organic pigments, one or more of pigments commonly used in this type of heat-sensitive recording material can be selected. Specific examples thereof include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, surface-treated inorganic pigments such as calcium and silica, and urea-formalin resin. And organic pigments such as styrene / methacrylic acid copolymer and polystyrene resin.

In the present invention, the leuco dye used in the heat-sensitive coloring layer is used alone or in combination of two or more.
As such leuco dyes, those applied to this type of heat-sensitive recording material are arbitrarily applied, and examples thereof include triphenylmethanephthalide, triallylmethane, fluoran, phenothiazine, and thioferoran. , Xanthene type, spiropyran type, indolinophthalide type,
Azaphthalide type, chromenopyrazole type, methine type, rhodamine anilinolactam type, rhodamine lactam type,
Leuco compounds of dyes such as quinazoline, diazaxanthene and bislactone are preferably used. Specific examples of such leuco dyes include, for example, those shown below.

3,3-bis (p-dimethylaminophenyl)-
Phthalide, 3,3-bis (p-dimethylaminophenyl) -6
-Dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis (p-dimethylaminophenyl)
-6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-
Dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofluoran, 3-dimethylamino-5,
7-dimethylfluoran, 3-N-methyl-N-isobutyl-6-
Methyl-7-anilinofluoran, 3-N-ethyl-N-isoamyl-6-methyl-7-anilinofluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-7,8-benzfluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3- (N-p-tolyl-N-ethylamino) -6-
Methyl-7-anilinofluoran, 3-pyrrolidino-6-
Methyl-7-anilinofluoran, 2- {N- (3'-trifluoromethylphenyl) amino} -6-diethylaminofluoran, 2- {3,6-bis (diethylamino) -9- (o-
(Chloranilino) xanthylbenzoate lactam｝, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-dibutylamino-7- (o -Chloroanilino) fluoran, 3-N-methyl-N-amylamino-6-methyl-7-anilinofluoran, 3-N-methyl-N
-Cyclohexylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino- 6-methyl-7- (2 ′, 4′-dimethylanilino) fluoran, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) fluoran, benzoylleucomethylene blue, 6'-chloro-8 '
-Methoxy-benzoindolino-spiropyran, 6'-bromo-8'-methoxy-benzoindolino-spiropyran, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5 '-Chlorophenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl) phthalide, 3- (2'-hydroxy-4'- (Diethylaminophenyl) -3- (2'-methoxy-5'-methylphenyl) phthalide, 3- (2'-methoxy-4'-dimethylaminophenyl)
-3- (2'-hydroxy-4'-chloro-5'-methylphenyl) phthalide, 3-morpholino-7- (N-propyl-trifluoromethylanilino) fluoran, 3-pyrrolidino-7-trifluoromethyl Anilinofluoran, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethylanilino) fluoran, 3-pyrrolidino-7- (di-p-
(Chlorophenyl) methylaminofluoran, 3-diethylamino-5-chloro-7- (α-phenylethylamino) fluoran, 3- (N-ethyl-p-toluidino) -7- (α-phenylethylamino) fluoran, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluoran, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluoran, 3-diethylamino-7-piperidinofluoran,
2-chloro-3- (N-methyltoluidino) -7- (pn-butylanilino) fluoran, 3- (N-methyl-N-isopropylamino)
-6-methyl-7-anilinofluoran, 3-dibutylamino-6
-Methyl-7-anilinofluoran, 3,6-bis (dimethylamino) fluorenespiro (9,3 ')-6'-dimethylaminophthalide, 3- (N-ethyl-N-cyclohexylamino) -5 ,
6-benzo-7-α-naphthylamino-4′-bromofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-N-ethyl-N- (2-ethoxypropyl) amino-6 -Methyl-7-anilinofluoran, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluoran, 3-
Diethylamino-6-methyl-7-mesitidino-4 ', 5'-benzofluoran, 3- (p-dimethylaminophenyl) -3- {1,1-bis (p-dimethylaminophenyl) ethylene-2-yl } Phthalide, 3- (p-dimethylaminophenyl) -3- {1,1-bis (p-dimethylaminophenyl) ethylene-2-yl} -6-dimethylaminophthalide, 3- (p-dimethylaminophenyl ) -3- (1-p-
Dimethylaminophenyl-1-phenylethylene-2-yl)
Phthalide, 3- (p-dimethylaminophenyl) -3- (1-p-dimethylaminophenyl-1-p-chlorophenylethylene-2-yl) -6-dimethylaminophthalide, 3- (4'-dimethylamino
-2'-methoxy) -3- (1 ''-p-dimethylaminophenyl-1 ''-
p-chlorophenyl-1 '', 3 ''-butadiene-4 ''-yl) benzophthalide, 3- (4'-dimethylamino-2'-benzyloxy) -3- (1 ''-p-dimethylaminophenyl -1 ''-phenyl-
1 '', 3 ''-butadiene-4 ''-yl) benzophthalide, 3-dimethylamino-6-dimethylamino-fluorene-9-spiro
3 '(6'-dimethylamino) phthalide, 3,3-bis {2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl} -4,5,6,7-tetrachlorophthalide , 3-bis {1,1-bis
(4-pyrrolidinophenyl) ethylene-2-yl} -5,6-dichloro-4,7-dibromophthalide, bis (p-dimethylaminostyryl) -1-naphthalenesulfonylmethane, bis (p-dimethylaminostyryl) ) -1-p-Tolylsulfonylmethane and the like.

In order to produce the heat-sensitive recording material of the present invention,
When the leuco dye and the developer are bound and supported on the support, various conventional binders can be appropriately used, and specific examples thereof include the following.

Polyvinyl alcohol, starch and derivatives thereof, methoxycellulose, hydroxymethylcellulose
, Hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, etc., cellulose derivatives, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide / acryl Water-soluble polymers such as acid ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, etc. Besides, polyvinyl acetate,
Polymethacrylates such as polyurethane, polyacrylic acid, polyacrylate, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene
Emulsions such as styrene / vinyl acetate copolymers and latexes such as styrene / butadiene copolymers and styrene / butadiene / acrylic copolymers.

In the present invention, various heat-fusible substances can be used as the sensitivity improver, and specific examples thereof include the following, but are not limited thereto. . Fatty acids such as stearic acid and behenic acid, fatty acid amides such as stearic acid amide and palmitic acid amide, fatty acid metal salts such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate and zinc behenate, p-benzyl Biphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, phenyl β-naphthoate, phenyl 1-hydroxy-2-naphthoate, methyl 1-hydroxy-2-naphthoate, diphenyl Carbonate, gliacol carbonate, dibensil terephthalate, dimethyl terephthalate, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 1,2-diphenoxyethane, 1,2 -
Bis (3-methylphenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane, 1,4-diphenoxybutane, 1,4-diphenoxy-2-butene, 1,2-bis (4-methoxyphenyl Thio) ethane, dibenzoylmethane, 1,4-diphenylthiobutane, 1,4-diphenylthio-2-butene, 1,3-bis (2-vinyloxyethoxy) benzene, 1,4-bis (2-vinyl (Oxyethoxy) benzene, p- (2-vinyloxyethoxy) bifel, p-aryloxybiphenyl, p-propargyloxybiphenyl, dibenzoyloxymethane, dibenzoyloxypropane, dibenzyldisulfide, 1,1-diphenylethanol, 1,1-diphenylpropanol, p-
Benzyloxybenzyl alcohol, 1,3-phenoxy-2
-Propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-octadecylcarbamoylbenzene, 1,2-bis (4-methoxyphenoxy) propane, 1,
5-bis (4-methoxyphenoxy) -3-oxapentane, dibenzyl oxalate, bis (4-methylbenzyl) oxalate,
Bis (4-chlorobenzyl) oxalate and the like.

When a heat-sensitive recording material is obtained according to the present invention, a leuco dye, the compound of the present invention as a color developer, if necessary, another color developer and an additive commonly used in this type of heat-sensitive recording material. Ingredients such as fillers, surfactants, lubricants, pressure-coloring inhibitors and the like can be used in combination. In this case, as a filler, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, kaolin, talc, surface-treated inorganic fine powder such as calcium and silica, Organic fine powders such as urea-formalin resin, styrene-methacrylic acid copolymer, polystyrene resin, and vinylidene chloride-based resin can be mentioned. As the lubricant, higher fatty acids and metal salts thereof, higher fatty acid amides, higher fatty acids Examples include esters, animal, vegetable, mineral or petroleum waxes.

In the present invention, a layer containing a pigment, a binder, a heat-fusible substance and the like can be provided between the intermediate layer and the heat-sensitive coloring layer, if necessary, as another intermediate layer. Furthermore, the recording material of the present invention can further improve the storage stability of a recorded image, and can be provided with a protective layer on the heat-sensitive coloring layer for the purpose of improving the writability of the recording material. In this case, the above-mentioned pigments, binders, heat-fusible substances and the like can be used as components constituting the protective layer. As for the layer configuration, it may be a single layer or a multilayer.

[0019]

Next, examples of the heat-sensitive recording material of the present invention will be described. All parts and percentages shown below are based on weight.

Example 1 The following mixtures were pulverized in a magnetic ball mill for 2 days to prepare [Solution A], [Solution B], and [Solution C]. [Solution A] 3-N, N-dibutylamino-6-methyl-7-anilinofluoran 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [Solution B] 2- (phenylacetamido) -benzoic acid 20 Part (Compound No. 2) 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [Liquid C] Calcium carbonate 20 parts Methylcellulose 20 parts Water 60 parts Next, [Liquid A] 10 parts, [Liquid B] 30 parts, [C Liquid] 40
And Chukyo Yushi zinc stearate dispersion (trade name
10 parts of Hydrin Z730 (concentration: 30%) were mixed to form a thermosensitive coloring layer-forming solution, which was commercially available high-quality paper (weighing 52 g).
/ M ² ) is applied and dried so that the amount of dye after drying is 0.5 g / m ² to form a heat-sensitive coloring layer, and the surface smoothness is further adjusted to 500 to 600 seconds. A thermosensitive recording material was prepared by calendering the surface of the layer.

Example 2 The following mixture was stirred and dispersed to obtain an intermediate layer forming liquid. [Liquid D] Fine hollow particle dispersion (copolymer resin mainly composed of 30 parts of styrene and acrylic) (solid content: 38%, average particle diameter: 0.7 μm, hollow ratio: 80%) Styrene / butadiene copolymer latex 10 Part water 60 parts The above-mentioned intermediate layer forming liquid was mixed with commercially available high quality paper (weighing 52 g / m2).
² ) Coating and drying were performed on the surface so that the weight after drying was 5 g / m ² to obtain an intermediate layer coated paper. Next, after applying the thermosensitive coloring layer forming liquid in Example 1 to the surface of the above-mentioned intermediate layer coated paper so that the amount of dye applied after drying becomes 0.5 g / m ² , the thermosensitive coloring layer was provided. And its surface smoothness is 500-6.
The surface of the layer was calendered so as to be 00 seconds to prepare a heat-sensitive recording material.

Example 3 A heat-sensitive recording material was prepared in the same manner as in Example 2 except that the following [Solution E] was used in place of the [Solution D]. [Solution E] Fine hollow particle dispersion (copolymer containing vinylidene chloride and acryloyl 30 parts nitrile as main components) (solid content: 32%, average particle diameter: 5 µm, hollow ratio: 92%) Styrene / butadiene copolymer latex 20 Part (solid content 47%) 60 parts water

Comparative Example 1 A heat-sensitive recording material was prepared in the same manner as in Example 1, except that the following [Solution F] was used instead of the [Solution B]. [Solution F] 4,4'-isopropylidenediphenol 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts

Comparative Example 2 A heat-sensitive recording material was prepared in the same manner as in Example 2 except that the above [Liquid F] was used instead of the [Liquid B].

Comparative Example 3 A heat-sensitive recording material was prepared in the same manner as in Example 2 except that the following [Solution G] was used in place of the [Solution B]. [Solution G] 4,4'-dihydroxy-3,3'-diallyldiphenylsulfone 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts

The thermosensitive recording material prepared as described above was printed by a printing device manufactured by Matsushita Electronic Components. The color density was measured with a Macbeth densitometer RD-914. Table 2 shows the above results.

[Table 2] Applied power: 0.68 w / dot, line cycle: 10 ms
/ Line

Further, the heat-sensitive recording material was printed with a heat block at 150 ° C. under the conditions of a pressure of 2 kg / cm ² and one second, and each of the printed samples was tested for water resistance, oil resistance and plasticizer resistance. . Table 3 shows the results.

[Table 3] Test conditions Oil resistance: Concentration after applying cottonseed oil for 16 hours under dry conditions at 40 ° C Plasticizer resistance: Applying DOA (di-2-ethylhexyl adipate) and storing for 16 hours under dry conditions at 40 ° C Later concentration

[0028]

As is clear from the above results, the heat-sensitive recording material of the present invention is excellent in color sensitivity, density and storage stability of recorded images, and is extremely practical.
Moreover, it has excellent high-speed recording characteristics.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-49-28411 (JP, A) JP-A-54-111905 (JP, A) JP-A-5-573 (JP, A) JP-A-4- 241987 (JP, A) JP-A-4-153080 (JP, A) JP-A-6-155925 (JP, A) Patent 3123825 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) B41M 5/28-5/34

Claims (2)

(57) [Claims] 1. A heat-sensitive recording material having a heat-sensitive coloring layer mainly composed of a leuco dye and a color developing agent for coloring the leuco dye on heating on a support, wherein the color developing agent is represented by the following general formula (I): A heat-sensitive recording material comprising a compound represented by the formula (1). Embedded image (In the formula, R represents an alkyl group, an aralkyl group, or an aryl group. However, the alkyl group is an alkoxy group, an acyl group,
The aromatic ring of the aralkyl group or the aryl group may have an alkyl group, an alkoxy group, an acyl group, an acyloxy group, a halogen atom, or a nitro group. ) 2. The heat-sensitive recording material according to claim 1, wherein an intermediate layer mainly composed of fine plastic spherical hollow particles made of a thermoplastic resin is provided between the support and the heat-sensitive coloring layer.