JP3239148B2 - 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,
In particular, the present invention relates to a heat-sensitive recording material which is excellent in color developability, preservability of an image portion and a background portion.

[0002]

2. Description of the Related Art A thermosensitive recording material is a recording material having a structure in which a thermosensitive coloring layer which develops a color by heating is formed on a support such as paper, synthetic paper, resin film or the like. Thermal printers with a built-in thermal head are used. This recording method is different from other methods in development,
There is no need to perform fixing or other processing, so that recording can be performed in a short time using a relatively simple device and the cost is low. In addition to copying books and documents, facsimile and ticket sales It is used in various fields such as printers and label recorders.

[0003]

However, as a problem of such a heat-sensitive recording material, a color image may fade or a background may be colored due to contact with chemicals such as fats and oils and plasticizers. Was. As a countermeasure against such a drawback, a protective layer containing a water-soluble polymer resin as a main component is conventionally provided on the thermosensitive coloring layer. Yes, not enough. Accordingly, an object of the present invention is to provide a heat-sensitive recording paper having high color-forming sensitivity without causing fading of a color-formed image due to chemicals such as oils and fats and a plasticizer, and coloration of the background.

[0004]

According to the present invention, there is provided a thermosensitive recording material comprising a support having thereon a thermosensitive coloring layer containing a leuco dye and a color developer as main components. There is provided a heat-sensitive recording material characterized by containing compounds represented by the following structural formulas [1], [2] and [3].

Embedded image

Embedded image

Embedded image The heat-sensitive recording material of the present invention contains the compound represented by the structural formula [1], [2], or [3] in the heat-sensitive coloring layer, so that the background portion and the image portion of the heat-sensitive coloring layer itself are included. The stability to oils and fats, plasticizers, etc. is improved, so that a protective layer mainly composed of a water-soluble polymer resin laminated on the thermosensitive coloring layer can be omitted, and if not, the adhesion of the protective layer can be reduced. The amount can be reduced, and the color sensitivity becomes high. Further, by providing an intermediate layer having a non-foamable plastic fine hollow body having an average particle size of 0.1 to 20 μm and a hollow ratio of 30% or more between the thermosensitive coloring layer and the support, the coloring sensitivity is further improved. be able to. With respect to the amount of the compound represented by the structural formulas [1], [2] and [3], the compound represented by the structural formula [2] is added to 1 part by weight of the compound represented by the structural formula [1]. 0.01-0.1
0 parts by weight of the compound represented by Structural Formula [3]
It is preferable that the content be about 0.15 parts by weight. If the amount of the compound represented by the structural formula [2] and the structural formula [3] is less than this, the effect on the above problem is not sufficient,
The effect does not change even if it is larger than this.

[0005] The intermediate layer comprising the plastic spherical hollow particles of the present invention as a main component acts as a heat insulating layer, and improves sensitivity by efficiently utilizing heat energy from a thermal head or the like. The average particle diameter of the plastic hollow particles is 0.1
２０20 μm and a hollow ratio of 30% or more,
The flexibility is further improved, the adhesion to the head is improved, and the dot reproducibility is improved.

The hollow particles used in the present invention are fine hollow particles which have a thermoplastic resin as a shell and contain air or other gas inside, and are already in a foamed state, and have an average particle diameter of 0.1. Those having a size of 1 to 20 μm are used. When the average particle diameter (particle outer diameter) is smaller than 0.1 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 20 μm, 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 30% or more in view of the heat insulating effect.
Those having 0% or more are more preferable. Those with a low hollow ratio
Due to insufficient heat insulation effect, heat energy from the thermal head is released through the support to the outside of the thermosensitive recording material,
Poor sensitivity improvement effect. Here, the hollow ratio is a ratio of the outer diameter to the inner diameter of the hollow particles, and is represented by the following equation (1).

## EQU1 ## The hollow ratio = (inner diameter of hollow particles) / (outer diameter of hollow particles) × 100 The fine hollow particles used in the present invention have a shell of a thermoplastic resin as described above. As the resin, a copolymer resin mainly containing vinylidene chloride and acrylonitrile is particularly preferable.

In the present invention, an inorganic or / and organic pigment is optionally used for the intermediate layer. In this case, a pigment having a lubricating amount of 30 ml / 100 g or more, preferably 80 ml / 100 g or more is selected. Is done. As these inorganic and / or organic pigments, one or more of the 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,
In addition to surface-treated inorganic pigments such as calcium and silica,
Organic pigments such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin can be used.

In the present invention, the leuco dye used in the thermosensitive coloring layer is applied alone or in combination of two or more.
As such leuco dyes, those applied to this type of heat-sensitive material are arbitrarily applied, and examples thereof include triphenylmethane, fluoran, phenothiazine, auramine, spiropyran, and indolinophthalide. A leuco compound of a dye is 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) xanthyl lactam 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- (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-
3'-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-trifluoromethylanilinofluoran, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethyl (Anilino) 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-benzyl-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.

The developer used in the heat-sensitive coloring layer of the present invention is a compound represented by the above structural formulas [I], [II] and [III]. Various other compounds having an electron accepting property, for example, phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof can be used in combination.
Specific examples thereof include the following.

4,4′-isopropylidenebisphenol,
4,4′-isopropylidenebis (o-methylphenol),
4,4′-secondary butylidenebisphenol 4,4′-isopropylidenebis (2-tert-butylphenol), 4,4′-cyclohexylidenediphenol,
4,4′-isopropylidenebis (2-chlorophenol),
2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis
(6-tert-butyl-2-methylphenol), 1,1,3
-Tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 4,4'-thiobis ( 6-tert-butyl-2-methylphenol),
4,4′-diphenolsulfone, 4-isopropoxy-4′-hydroxydiphenylsulfone, 4-benzyloxy-4′-hydroxydiphenylsulfone, 4,4′-diphenolsulfoxide, isopropyl P-hydroxybenzoate, P -Benzyl hydroxybenzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate, 1,7-bis (4-hydroxyphenylthio) -3,
5-dioxaheptane, 1,5-bis (4-hydroxyphenylthio) -3-oxapentane, 1,3-bis (4-hydroxyphenylthio) -propane, 1,3-bis (4-hydroxyphenylthio ) -2-Hydroxypropane, N, N′-diphenylthiourea, N, N′-di (m-chlorophenyl) thiourea, salicylanilide, 5-chloro-salicylanilide, 2-hydroxy-3-naphthoic acid, 2 -Hydroxy-1
-Naphthoic acid, 1-hydroxy-2-naphthoic acid, metal salts of hydroxynaphthoic acid such as zinc, aluminum and calcium, bis- (4-hydroxyphenyl) acetic acid methyl ester, bis- (4-hydroxyphenyl) acetic acid benzyl ester , 1,3-bis (4-hydroxycumyl) benzene, 1,4
-Bis (4-hydroxycumyl) benzene, 2,4'-diphenolsulfone, 3,3'-diallyl-4,4'-diphenolsulfone, α, α-bis (4-hydroxyphenyl) -α- Methyltoluene, antipyrine complex of zinc thiocyanate,
Tetrabromobisphenol A, tetrabromobisphenol S, 4,4'-thiobis (2-methylphenol), 4,4'-
Thiobis (2-chlorophenol) 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, cellulose derivatives such as hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, etc .; -Da, polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, styrene /
Maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein and other water-soluble polymers, polyvinyl acetate, polyurethane, polyacrylic acid, Polyacrylate, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene /
Emulsions such as 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-diphenoxy-2-butene, 1,2-
Bis (4-methoxyphenylthio) ethane, dibenzoylmethane, 1,4-diphenylthiobutane, 1,4-diphenylthio
2-butene, 1,3-bis (2-vinyloxyethoxy) benzene, 1,4-bis (2-vinyloxyethoxy) benzene, p- (2
-Vinyloxyethoxy) bifer, p-aryloxyphenyl, 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, oxalic acid Bis (4-chlorobenzyl) and the like.

In the present invention, if necessary, auxiliary additives commonly used in this type of heat-sensitive recording material, for example,
A filler, a surfactant, a lubricant, a pressure coloring inhibitor and the like can be used in combination. In this case, as the 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 or silica Other examples include fine organic powders such as urea-formalin resin, styrene / methacrylic acid copolymer, polystyrene resin, and vinylidene chloride resin. Examples of the lubricant include higher fatty acids and metal salts thereof, higher fatty acid amides, Examples include fatty acid esters, various animal, vegetable, mineral or petroleum waxes.

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

In the present invention, the amounts of the leuco dye, the developer and the sensitizer are 0.5 to 10.0 parts by weight of the developer and 0.5 to 10.0 parts by weight, based on 1 part by weight of the leuco dye. 10.0 parts by weight, preferably 1 to 5 parts by weight are preferred.

[0018]

[A liquid]

3-dibutylamino-6-methyl-7-anili 20 parts Nofluoran 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [Solution B] 4-isopropoxy-4'-hydroxydiph 20 parts phenyl sulfone 2,2'-methylenebis (4-methyl-6-t 1 part-butylphenol) 4,4'-isopropylidenebis (2,6-di 2 parts bromophenol) 10% aqueous solution of polyvinyl alcohol 23 parts Water 54 parts [Solution C] Calcium carbonate 20 Parts methylcellulose 20 parts water 60 parts Next, [Solution A] 10 parts, [Solution B] 30 parts, [Solution C] 40
The resulting mixture was mixed to form a thermosensitive coloring layer-forming solution, which was applied to the surface of a commercially available high-quality paper (basis weight: 52 g / m ² ) so that the amount of dye after drying was 0.5 g / m ² , followed by drying. After the heat-sensitive coloring layer was provided, the above [Solution C]: 10 parts, a 10% aqueous solution of polyvinyl alcohol: 50 parts, and a dispersion of zinc stearate manufactured by Chukyo Yushi (trade name: Hydrin Z730, concentration: 3)
0%): 2 parts and water: 38 parts were mixed to form a protective layer liquid, and the amount of the liquid after drying on the thermosensitive coloring layer was 3 g / m ²
After coating and drying to provide a protective layer, the surface of the layer was further calendered so that the surface smoothness was 500 to 600 seconds, to produce a heat-sensitive recording material of Example-1. Example 2 The following mixture was stirred and dispersed to obtain an intermediate layer forming liquid. [D Liquid] Fine hollow particle dispersion (copolymer resin mainly composed of 30 parts of styrene and acryl) (solid content concentration: 27.5%, average particle diameter: 0.6 μm, hollow ratio: 40%) Styrene / butadiene copolymerization Latex (10 parts solids, 47.5% concentration) Water 60 parts
After drying, the surface of ² ) was applied and dried so as to have a weight of 5 g / m ² to obtain an intermediate layer coated paper. Next, the heat-sensitive color-forming layer was formed by applying the heat-sensitive color-forming layer forming liquid of Example-1 on the surface of the intermediate coated paper so that the amount of dye after drying was 0.5 g / m ² . After that, the surface smoothness further becomes 500 ~
The surface of the layer was calendered so as to have a duration of 600 seconds to prepare a heat-sensitive recording material of Example-2. Comparative Example 1 The following mixtures were each pulverized in a magnetic ball mill for 2 days to prepare [Solution E]. [Solution E] 2,2'-bis (4-hydroxyphenyl) propane 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts The above [Solution E] is used in place of [Solution B] in Example-1. Except for the above, the heat-sensitive recording paper of Comparative Example-1 was obtained in the same manner as in Example-1. Comparative Example-2 The 2,2'-methylenebis (4-
Except for methyl-6-t-butylphenol), a thermal recording paper of Comparative Example-2 was obtained in the same manner as in Example-1, except that 22 parts of a 10% aqueous solution of polyvinyl alcohol and 56 parts of water were used. . Comparative Example-3 Except for 4,4'-isopropylidenebis (2,6-dibromophenol) of [Solution B] of Example-1, 21 parts of a 10% aqueous solution of polyvinyl alcohol was used, and water was 58 parts. Except for the above, a thermosensitive recording paper of Comparative Example-3 was obtained in the same manner as in Example-1. Comparative Example-4 2,2'-Methylenebis (4-
Except for methyl-6-t-butylphenol) and 4,4'-isopropylidenebis (2,6-dibromophenol), except that 20 parts of a 10% aqueous solution of polyvinyl alcohol and 60 parts of water were used. In the same manner as in -1, a thermosensitive recording paper of Comparative Example-4 was obtained. The thermal recording material prepared as described above is printed by a thermal paper coloring tester manufactured by Okura Electric Co., Ltd., and the coloring density is measured by a Macbeth densitometer RD.
The concentration was measured at -914. Further, cottonseed oil was applied to the image area and the background area printed at 0.6 ms,
After standing for 24 hours under RY environmental conditions, the density of the image area and the background area were measured. Table 1 shows the above results. (Below)

[Table 1]

As is clear from Table 1, the heat-sensitive recording material of the present invention has a high color-forming sensitivity, and is excellent in background color development by contact with chemicals such as oils and fats and stability of a color-formed image.

Continuation of the front page (72) Inventor Shinji Takano 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (56) References JP-A-2-239977 (JP, A) JP-A-5-278342 (JP, A) JP-A-62-144991 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/28-5/34 CAPLUS (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] 1. A thermosensitive recording material comprising a support and a thermosensitive coloring layer comprising a leuco dye and a color developer as main components, wherein the thermosensitive coloring layer comprises the following structural formulas [1] and [2]. And a compound represented by [3]. Embedded image Embedded image Embedded image 2. An intermediate layer having a non-foamable plastic fine hollow body having an average particle diameter of 0.1 to 20 μm and a hollow ratio of 30% or more is provided between the thermosensitive coloring layer of claim 1 and a support. The heat-sensitive recording material according to claim 1, wherein: 3. The amount of the compound represented by Structural Formulas [1], [2] and [3] of claim 1 is added to 1 part by weight of the compound represented by Structural Formula [1] with respect to 1 part by weight of the compound represented by Structural Formula [2] 2. The heat-sensitive recording according to claim 1, wherein the compound represented by the formula (1) is 0.01 to 0.10 parts by weight, and the compound represented by the structural formula (3) is 0.05 to 0.15 parts by weight. material.