JPH11254824A - Thermal recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording medium which has design properties with a vividly colored face and outstanding anti marring properties. SOLUTION: A layer composed mainly of a colorant and an acidic material is formed using a coating obtained by dispersing or dissolving the colorant and the acidic material in an organic solvent, on one of the faces of a support. Further, a layer composed mainly of a leuco dye is formed on the layer composed mainly of the colorant and the acidic material using a coating obtained by dispersing the leuco dye in water. In addition, a protecting layer composed mainly of a water-soluble polymer and/or a synthetic resin emulsion or a protecting layer composed mainly of an ultraviolet-curable resin, is formed on the layer composed mainly of the leuco dye. Next, a protecting layer composed mainly of the water-soluble polymer and/or the synthetic resin emulsion is formed on the layer composed mainly of the leuco dye, and then a second protecting layer composed mainly of the ultraviolet-curable resin is formed on the protecting layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive recording medium capable of recording an image by a thermosensitive recording system. More specifically, the present invention relates to a thermosensitive recording medium whose background is vividly colored.

[0002]

2. Description of the Related Art In general, a thermosensitive recording medium comprises a support and a thermosensitive coloring layer formed on the support. The thermosensitive coloring layer is heated by a thermal head, a hot pen, a laser beam or the like to obtain a thermosensitive coloring. This is to react a coloring agent in a layer instantly to form a recorded image. For example, according to JP-B-43-4160 and JP-B-45-14039, the principle based on the reaction between a leuco dye and an acidic substance is disclosed. Is a widely known thermosensitive recording medium.

[0003] Such a thermosensitive recording medium has such advantages that a recorded image can be formed by a relatively simple apparatus, maintenance is easy, and no noise is generated at the time of recording. , Facsimile, measuring recorder, computer and other terminal printers, automatic ticket vending machines, bar code labels, etc.

In particular, in recent years, the use of heat-sensitive recording materials has been expanding to various types of tickets, receipts, ATMs for banks, gas and electricity meter reading, and the like. Therefore, characteristics that were not required in the past have been demanded. As one of them, there has been a demand for coloring a background portion in order to give a design and a sense of quality.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material colored in an arbitrary color.

[0006]

According to the present invention, a layer comprising a colorant and an acidic substance as main components is provided on one side of a support by a coating material in which both are dispersed or dissolved in an organic solvent. This is a heat-sensitive recording medium provided with a coating material in which a layer containing a leuco dye as a main component is dispersed in water.

Further, according to the present invention, a protective layer mainly composed of a water-soluble polymer and / or a synthetic resin emulsion or a protective layer mainly composed of an ultraviolet curable resin is provided on the layer mainly composed of the leuco dye. Thermal recording medium.

The present invention further provides a protective layer mainly composed of a water-soluble polymer and / or a synthetic resin emulsion on the layer mainly composed of the leuco dye, and a second layer mainly composed of an ultraviolet-curable resin. It is a thermosensitive recording medium provided with a protective layer.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention have studied a coloring method. The method includes: a method of providing a coloring layer on a support and then providing a thermosensitive coloring layer, or a method of providing a coloring on a support. A method of providing a thermosensitive coloring layer containing an agent is conceivable, but 1 has a drawback that the coloring layer is seen through the thermosensitive coloring layer and lacks vividness, and 2 has a possibility that the coloring agent reacts with the thermosensitive coloring component. There is a problem that there is a limitation on the hues that can be obtained.

The present inventors have conducted intensive studies in order to eliminate these disadvantages and have accomplished the present invention. That is, the layer above the colored layer should be as thin as possible to maintain vividness. It has been found that it is preferable that the developer and the leuco dye are separated from each other in terms of obtaining a clear colored hue and background fog.

When the colored layer is applied using an organic solvent-based paint, a vivid hue is obtained. That is, after providing a colored layer on a support using a paint composed of a colorant soluble or dispersed in an organic solvent and an acidic substance (a color developer), a paint in which a leuco dye is dispersed in water is applied to the colored layer. It was found that an excellent colored thermosensitive recording medium could be obtained by providing a leuco dye layer by coating on top.

Since the colorant and the developer are dissolved or dispersed in an organic solvent, the applied colored layer has a vivid hue, and since the developer is separated from the leuco dye, background fogging occurs. Absent.

The thickness of the leuco dye layer provided on the upper side is thinner than that of the color developing agent and can be made to be half or less of the thickness of the ordinary thermosensitive coloring layer, so that the lower hue is not hindered. The reason for using a water-based paint for the application of the leuco dye layer is that when an organic solvent is used, the developer of the colored layer dissolves and reacts with the leuco dye to cause background fog.

Hereinafter, each element constituting the present invention will be described in more detail. As the organic solvent, xylene, toluene, isopropyl alcohol, methyl ethyl ketone, methyl isobutyl ketone, mineral spirit, solvent naphtha and the like can be used.

As the coloring agent, a coloring dye or pigment which is soluble or dispersible in these organic solvents can be used. Examples thereof are as follows. I. S
solvent Yellow 16, C.I. I. Solv
ent Yellow 61, C.I. I. Solvent
Yellow 56, C.I. I. Solvent Or
angel 6, C.I. I. Solvent Orange
37, C.I. I. Solvent Red 25, C.I.
I. Solvent Red 27, C.I. I. Solv
ent Red 83, C.I. I. Solvent Vi
olet 21, C.I. I. Solvent Violet
t13, C.I. I. Solvent Blue 2,
C. I. Solvent Blue 25, C.I. I. D
isperse Yellow 4, C.I. I. Disp
erse Yellow 31, C.I. I. Disper
se Red 11, C.I. I. Disperse Bl
ue27, C.I. I. Disperse Violet
24 and the like.

The acidic substance is a solid at room temperature, melts by heating and comes into contact with the leuco dye compound to become a color developer, and is a phenol derivative, an aromatic carboxylic acid derivative, N, N'-diarylthioate. Polyvalent metal salts such as urea derivatives and zinc salts of organic compounds can be used. A substance that is more soluble in an organic solvent is more preferable.

Specifically, 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-ethyl-6
-Tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-2-methylphenol), 4,4'-diphenolsulfone, 4-isopropoxy-4'-hydroxyphenylsulfone, 4-benzyloxy- 4'-hydroxydiphenyl sulfone, 4,
4'-diphenol sulfoxide, 2,2-bis (3-
Allyl-4-hydroxyphenyl) sulfone,

Isopropyl p-hydroxybenzoate, p
-Benzyl hydroxybenzoate, benzyl protocaquitenate, 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, zinc of hydroxynaphthoic acid, aluminum,
Metal salts such as calcium, bis (4-hydroxyphenyl) acetic acid methyl ester, bis (4-hydroxyphenyl) acetic acid benzyl ester, bis (4-hydroxyphenyl) acetic acid butyl ester,

1,3-bis (4-hydroxycumyl) benzene, 1,4-bis (4-hydroxycumyl) benzene, 2,4'-diphenol sulfone, 3,3'-diallyl-4,4 '-Diphenol sulfone, α, α-bis (4-hydroxyphenyl) α-methyltoluene, antipyrine complex of zinc thiocyanate, tetrabromobisphenol A, tetrabromobisphenol S and the like are used.

As a binder for fixing a layer containing a colorant and an acidic substance as main components on a support, the above-mentioned resins soluble in an organic solvent can be used. For example, a vinyl chloride / vinyl acetate copolymer, a vinyl chloride / vinyl acetate / maleic acid copolymer, polyurethane, saturated polyester, polyester polyurethane, epoxy resin, phenoxy resin, nitrocellulose, melamine resin, chlorinated polyethylene, and the like are included.

Examples of the method for providing a layer containing the colorant and the acidic substance as main components of the present invention include coating methods such as blade coater, air knife coater, rod coater, reverse roll coater, gravure printing, letterpress printing, Printing methods, such as lithographic printing, can be mentioned, and are selected according to the properties of the coating agent. The coating amount of the layer is not particularly limited, but is generally 1 to 15 g / m ² , preferably 1 to 10 g in terms of dry weight.
/ M ² .

The layer containing a leuco dye as a main component and provided on the layer containing a colorant and an acidic substance as main components of the present invention will be described. Conventionally known leuco dyes are used, examples of which are shown below.

(1) Triarylmethane compound, for example, 3,3-bis (p-dimethylaminophenyl)
-6-dimethylaminophthalide (crystal violet lactone), 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl)
Phthalide, 3- (p-dimethylaminophenyl) -3-
(2-phenylindol-3-yl) phthalide, 3,
3-bis (p-ethylcarbazol-3-yl) -3-
Dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -5-dimethylaminophthalide and the like;

(2) Diphenylmethane compounds, for example, 4,4-bis-dimethylaminobenzhydrin benzyl ether, N-halophenylleucouramine, N-2,4,5-trichlorophenylleucouramine;

(3) Xanthene compounds For example, rhodamine B-anilinolactam, 3-diethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-butylaminofluoran, 3-diethylamino-7- (2- Chloroanilino) fluoran, 3
-Diethylamino-6-methyl-7-anilinofluoran, 3-piperidino-6-methyl-7-anilinofluoran, 3-ethyl-tolylamino-6-methyl-7-anilinofluoran, 3-cyclohexyl- Methylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-chloro-7- (β-ethoxyethyl) aminofluoran, 3-diethylamino-6-chloro-7-
(Γ-chloropropyl) aminofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-
N-cyclohexyl-N-methylamino-6-methyl-
7-anilinofluoran, 3-diethylamino-7-phenylfluoran, 3- (N-isoamyl-N-ethylamino) -6-methyl-7-anilinofluoran, 3-
Dibutylamino-6-methyl-7-anilinofluoran and the like;

(4) Thiazine compounds such as benzoyl leucomethylene blue and p-nitrobenzoyl leucomethylene blue; (5) Spiro compounds such as 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran and 3-benzyl -Spiro-dinaphthopyran, 3-methylnaphtho- (3-methoxy-benzo) -spiropyran, and the like, and a mixture thereof is used, and is selected based on desired properties according to the use of the thermosensitive recording medium.

As the binder used in the layer containing leuco dye of the present invention as a main component, an aqueous binder is used. Starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, denatured Water-soluble binders such as polyvinyl alcohol, styrene-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, methyl acrylate-butadiene copolymer, etc. And hydrophobic resin emulsions.

In the layer containing leuco dye as a main component, if necessary, other additives, for example, inorganic or organic pigments such as clay, calcium carbonate, synthetic silica, aluminum hydroxide, talc, titanium oxide, zinc oxide, etc. Antioxidants for stabilization, ultraviolet absorbers, water-resistant agents for improving water resistance, phenolic resins, surfactants, conventionally used waxes, metal salts of higher fatty acids, etc. can be added. . Although the coating amount of the layer is not particularly limited, it is generally applied in a dry weight range of about 1 to 15 g / m ² , preferably about 1 to 10 g / m ² .

For the purpose of promoting color development, the following heat-fusible substances are added to a layer mainly containing a colorant and an acidic substance or a layer mainly containing a leuco dye or between two layers. You may. For example, fatty acids such as stearic acid and behenic acid, stearic acid amide, p-benzylbiphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, β-naphthoic acid phenyl ester, -Hydroxy-2-naphthoic acid phenyl ester, 1-hydroxy-
2-naphthoic acid methyl ester,

Alternatively, diphenyl carbonate, dibenzyl terephthalate, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-dibenzyloxoinaphthalene, 1,2-bis (phenoxy) ethane, , 2- (3-methylphenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane,
1,4-bis (phenoxy) butane, 1,4-bis (phenoxy) -2-butene, dibenzoylmethane, 1,4
-Bis (phenylthio) butane, 1,4-bis (phenylthio) -2-butene,

Further, 1,3-bis (2-vinyloxyethoxy) benzene, 1,4-bis (2-vinyloxyethoxy) benzene, p- (2-vinyloxyethoxy) biphenyl, p-aryloxybiphenyl, p-
Propargyloxybiphenyl, dibenzoyloxymethane, 1,3-dibenzoyloxypropane, dibenzyldisulfide, 1,1-diphenylethane, 1,1-diphenylpropanol, p- (benzyloxy) benzyl alcohol, 1,3- One or more of diphenoxy-2-propanol, N-octadecylcarbonyl-p-methoxycarbonylbenzene, N-octadecylcarbamoylbenzene, and the like are used.

By providing a protective layer mainly containing a water-soluble polymer and / or a synthetic resin emulsion or a protective layer mainly containing an ultraviolet-curable resin on a layer mainly containing a leuco dye, It is preferable because a stable thermosensitive recording medium can be obtained. For the protective layer, any of the materials used for a conventionally known protective layer can be used.
A, modified PVA, starch, casein, and a synthetic resin emulsion can be used. The UV-curable resin will be described later.

By providing a protective layer mainly composed of an ultraviolet curable resin on the protective layer or on a layer mainly composed of leuco dye, excellent heat sensitivity which is glossy and is not affected by mechanical pressure. A recording medium can be obtained, which is preferable. Both the protective layer containing a water-soluble polymer and / or a synthetic resin emulsion as a main component and the protective layer containing a UV-curable resin as a main component have a coating amount of 1 to 10 g / m ² , preferably ² to 5 g / m ^{2 on} a dry weight basis. If it is ² , a sufficient effect can be obtained.

The UV-curable resin is described in detail in published books and magazines such as “Taiseisha: Light / Radiation Curing Technology”. In short, photopolymerizable monomers, prepolymers, or It is obtained by polymerizing by irradiating ultraviolet rays to an ultraviolet-curable resin composition containing polymers and a photopolymerization initiator as essential components. The monomer and the prepolymer or polymer are compatible and have copolymerizability. As the prepolymer, unsaturated polyester, epoxy, acrylic, various polyesters and the like can be used, and as the monomer, various ethylene derivatives can be mentioned. The protective layer mainly composed of an ultraviolet curable resin is preferably provided by a normal printing method.

The support used in the present invention is not particularly limited, and examples thereof include high quality paper, recycled paper, matte paper, oil resistant paper, coated paper, art paper, cast coated paper, finely coated paper, and resin laminated paper. And polyolefin-based synthetic paper, synthetic fiber paper, synthetic resin film and the like can be used as appropriate. It is also effective to perform a smoothing process using a super calendar after forming each layer in order to improve the image quality.

[0038]

EXAMPLES The present invention will be described more specifically with reference to production examples, but the present invention is not limited to these examples. Formulation,
The coating amount and the like are indicated by solid components or active ingredients on a weight basis.

Example 1 Preparation of “Layer Containing Colorant and Acidic Substance as Main Components” A paint having the following composition was applied by a gravure coater and dried. Toyo Ink Multiset (Blue) 100g Toyo Ink LPNYB Additive 3g Toyo Ink 150TC 5g Toyo Ink LP-402 25-30g Bis (3-allyl-4-hydroxyphenyl) -sulfone 100g Toluene 500g Coating A liquid was prepared, and applied to a polyolefin-based synthetic paper of 60 g / m ² in a rice area such that the coating amount after drying was 4 g / m ² to provide a layer mainly composed of a colorant and an acidic substance.

Preparation of “Layco Dye-Based Layer” Preparation of Leuco Dye Solution 3-Di (N-butylamino) -7- (2-chloroanilino) fluoran ... 10 g 20% polyvinyl alcohol (Kuraray Povar 105, Kuraray) This composition was pulverized with a sand mill until the average particle diameter became 0.8 μm. 20% polyvinyl alcohol
(Kuraray Povar 105, made by Kuraray) 6 g, silica (P
-527 Mizusawa Chemical Co., Ltd.) (5 g) and a 30% zinc stearate dispersion (D-523 made by Chukyo Yushi) were mixed and stirred to obtain a leuco dye solution. The obtained coating liquid was provided on a layer mainly containing a colorant and an acidic substance so that the dry weight was 2 g / m ² . Thus, the sample of Example 1 was obtained.

Example 2 Example 1 was repeated except that silica and zinc stearate were omitted from the leuco dye solution composition of Example 1.
A recording medium A was obtained in exactly the same manner as described above, and the following protective layer was formed thereon. Formation of protective layer 40 g of 10% carboxy-modified polyvinyl alcohol (T-215 manufactured by Nippon Gosei Co., Ltd.), silica (P-52)
7 Mizusawa Chemical Co., Ltd.) 10 g, 30% zinc stearate dispersion (D-523, Chukyo Yushi Co., Ltd.) 0.9 g, glyoxal 10 g, and water 200 g were mixed and stirred to obtain a coating solution for a protective layer. The obtained coating liquid was applied onto the recording medium A so as to have a dry weight of 2 g / m ² and dried to obtain a sample of Example 2.

(Examples 3 and 4) On the recording medium A of Example 2,
In addition, a UV curable resin (N-1815 manufactured by Nippon Kayaku Co., Ltd.) was applied on the sample of Example ² at 2 g / m ² to obtain samples of Examples 3 and 4.

(Printing test) A commercially available label printer (Nippon Shinbo XP-
6250). It was confirmed that all of the samples obtained in Examples 1 to 4 were able to perform clear black printing on the surface having vivid coloring.

(Scratch test) Even if the heat-sensitive recording materials of Examples 1 to 4 were strongly rubbed with nails, no color was formed. Usually, the leuco dye and the acidic substance have been significantly improved as compared with a normal thermosensitive recording paper in which they are present in the same recording layer.

[0045]

As described above, by adopting the constitution of the present invention, a heat-sensitive recording medium having a vividly colored surface, having a design property and having excellent abrasion resistance was obtained.

Claims (3)

[Claims] 1. A layer comprising a colorant and an acidic substance as main components is provided on one side of a support with a coating material in which both are dispersed or dissolved in an organic solvent. A heat-sensitive recording material comprising a coating layer in which a coating layer is dispersed in water. 2. A method according to claim 1, wherein a protective layer mainly composed of a water-soluble polymer and / or a synthetic resin emulsion or a protective layer mainly composed of an ultraviolet curable resin is provided on the layer mainly composed of a leuco dye. The heat-sensitive recording material according to claim 1, wherein 3. A protective layer mainly composed of a water-soluble polymer and / or a synthetic resin emulsion is provided on a layer mainly composed of a leuco dye, and a second layer mainly composed of an ultraviolet-curable resin is provided.
2. The heat-sensitive recording material according to claim 1, wherein a protective layer is provided.