JPH08282114A - Thermal recording material and production thereof - Google Patents

Abstract

PURPOSE: To obtain a thermal recording material excellent in preservation characteristics and high in background whiteness by adding a specific ultraviolet absorber and a fluorescent brightener composed of a 4,4-diaminostilbene-2,2'- disulfonic acid derivative to a thermal color forming layer. CONSTITUTION: In a thermal recording material wherein a thermal color forming layer based on a leuco dye and a coupler allowing the dye to form a color at a time of heating is provided on a support, the thermal color forming layer contains an ultraviolet absorber represented by formula and a fluorescent brightener composed of a 4,4'-diaminostilbene-2,2'-disulfonic acid derivative. Or, the protective layer based on an org. polymeric substance formed on the thermal color forming layer contains two kinds of the above mentioned compds. The content of the fluorescent brightener in the thermal color forming layer is set to 0.01 pts.wt. or less per 1 pts.wt. of the leuco dye. The content of the fluorescent brightener in the protective layer is set to 0.01 pts.wt. or less per 1 pts.wt. of the resin of the protective layer.

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, and more particularly to a heat-sensitive recording material having excellent storage characteristics such as light resistance and high whiteness of the background, and a method for producing the same.

[0002]

2. Description of the Related Art A general heat-sensitive recording material is a colorless or pale color developing agent such as a leuco dye on a support such as paper or film, and a phenol as a color developing agent for developing the color when heated.
With a thermosensitive coloring layer formed by dispersing a coloring component composed of an acidic substance such as an organic compound or an organic acid together with a binder, or by further adding a filler, a sensitivity improver, a lubricant, and other auxiliaries thereto. For example, Japanese Patent Publication No. 43-4160 and Japanese Patent Publication No. 4160
It is disclosed in No. 5-14039, Japanese Patent Publication No. 48-127736, etc. Since this type of heat-sensitive recording material obtains a color image by an instantaneous chemical reaction between a color-developing agent and a color-developing agent during heating, it is subjected to complicated processing such as development and fixing as compared with other recording materials. In addition to being used for copying books, documents, etc., it is possible to obtain records in a short time with a relatively simple device, there is little noise and environmental pollution, and there is no cost. It is widely used as a recording material for various information and measuring instruments such as facsimiles, telesixes, and medical measuring instruments, as well as CAD paper, food POS label, and industrial label.

In such a usage environment of the heat-sensitive recording material, the heat-sensitive recording material may be exposed to light such as sunlight or a fluorescent lamp, and the color-developing component of the heat-sensitive recording material undergoes a change due to light energy, resulting in fading of a color-developed image. However, there are drawbacks such that the background is easily colored and the light resistance is poor. In order to prevent this, the following methods have been studied conventionally. That is, a method of incorporating a benzophenone-based UV absorber or a phenol-based antioxidant in a thermosensitive coloring layer containing a color-forming substance and a phenolic substance that develops color when heated (JP-A-54-18752), heat-sensitive A method of providing a protective layer containing an ultraviolet absorber on the color forming layer (JP-A-60-1)
No. 12487), and a method of incorporating a pigment or dye having light absorption in the light wavelength range of 400 to 600 nm into the thermosensitive coloring layer and / or the protective layer provided on the thermosensitive coloring layer (JP-A-61-61).
-134292) and the like are known.

[0004]

In the conventional method using an ultraviolet absorber or the like, the ultraviolet absorber or the like has a light wavelength of 400 n.
In many cases, it has absorption near m, and the UV absorbers are light yellow or yellowish, so the background of the heat-sensitive recording material is light yellow or yellowish and the whiteness of the background is lowered. There's a problem. Further, when an optical brightener is added to improve this, the function of the ultraviolet absorber or other organic compound contained in the layer such as the thermosensitive coloring layer or the protective layer to which the optical brightener is added is It adversely affects the storage stability such as light resistance, or deteriorates the stability of the coating liquid such that the coating liquid for forming the thermosensitive coloring layer or the protective layer thickens with time or liquid separation occurs. There's a problem. An object of the present invention is to provide a heat-sensitive recording material having a high degree of whiteness of the background and excellent light resistance without causing the background to be colored by light, and a coating for forming a thermosensitive coloring layer or a protective layer. It is an object of the present invention to provide a method for producing a heat-sensitive recording material having excellent liquid stability.

[0005]

The above object of the present invention can be achieved by a heat-sensitive recording material and a method for producing the same as set forth in the claims. That is, according to the present invention, in a thermosensitive recording material having a thermosensitive coloring layer containing a leuco dye and a color developing agent for coloring the dye on heating as a main component, on a support,
The heat-sensitive coloring layer contains an ultraviolet absorber represented by the following structural formula (1) and a fluorescent whitening agent composed of a 4,4'-diaminostilbene-2,2'-disulfonic acid derivative. Recording material is provided.

Embedded image Further, according to the present invention, a leuco dye and a thermosensitive coloring layer containing, as a main component, a color developer capable of coloring the dye when heated, on a support,
And a heat-sensitive recording material having a protective layer containing an organic polymer as a main component formed in the heat-sensitive color forming layer, wherein the heat-sensitive color forming layer or the protective layer comprises an ultraviolet absorber represented by the structural formula (1), There is provided a heat-sensitive recording material containing a fluorescent whitening agent composed of a'-diaminostilbene-2,2'-disulfonic acid derivative. Further, according to the present invention, a main component is a thermosensitive coloring layer mainly composed of a leuco dye and a color developing agent for coloring the dye on a support, and an organic polymer substance formed on the thermosensitive coloring layer. In the heat-sensitive recording material having a protective layer, the ultraviolet absorber represented by the structural formula (1) and 4,4′-diaminostilbene-2,
There is provided a heat-sensitive recording material characterized in that one of the fluorescent whitening agents comprising a 2'-disulfonic acid derivative is contained in the heat-sensitive color forming layer and the other is contained in the protective layer. Further, according to the present invention, the content of the fluorescent whitening agent in the thermosensitive coloring layer is 0.01 parts by weight or less with respect to 1 part by weight of the leuco dye, and the content of the fluorescent whitening agent in the protective layer is protected. The heat-sensitive recording material is provided in an amount of 0.01 parts by weight or less with respect to 1 part by weight of the layer resin. Furthermore, according to the present invention, an aqueous dispersion containing a leuco dye and a color developer and a binder for coloring the dye on heating is applied on a support and dried to form a thermosensitive coloring material. In the production method, the aqueous dispersion comprises an ultraviolet absorber represented by the structural formula (1) and 4,
Provided is a method for producing a heat-sensitive recording material, which comprises a fluorescent whitening agent composed of a 4'-diaminostilbene-2,2'-disulfonic acid derivative, and to provide a support on a support,
A leuco dye and an aqueous dispersion containing a developer and a binder that cause the dye to develop color when heated are applied and dried to form a thermosensitive coloring layer, on which a solution containing an organic polymer as a main component is applied and dried. In the method for producing a heat-sensitive recording material in which a protective layer is formed, the aqueous dispersion containing a leuco dye, a developer and a binder, or a solution containing an organic polymer as a main component is the above structural formula (1). And an ultraviolet absorber represented by 4,4'-
There is provided a method for producing a heat-sensitive recording material, characterized in that it contains both or either of a fluorescent whitening agent comprising a diaminostilbene-2,2'-disulfonic acid derivative.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have investigated the types of ultraviolet absorbers and optical brighteners, the layers to which these are added, the amount added, etc., and as a result, used the compound of the above structural formula as an ultraviolet absorber, In addition to this, 4,4 'as a fluorescent whitening agent
-Using a diaminostilbene-2,2'-disulfonic acid derivative, both of which are contained in the thermosensitive color forming layer or the protective layer, or one of them is contained in the thermosensitive color forming layer and the other is contained in the protective layer, A heat-sensitive recording material having a high degree of whiteness on the background and excellent light resistance without coloring of the background due to light is obtained, and in the production of the heat-sensitive recording material, these ultraviolet absorbers and / or fluorescent whitening agents are used. The coating liquid for the thermosensitive color developing layer or the coating liquid for the protective layer containing the agent does not thicken with time or liquid separation occurs, and the stability of the coating liquid is excellent and uniform coating can be performed. The present invention has been found out and the present invention has been completed.

The content of the ultraviolet absorber in the thermosensitive coloring layer is preferably 0.1 part by weight to 5 parts by weight, more preferably 0.2 part by weight to 2 parts by weight, based on 1 part by weight of the leuco dye. The content of the ultraviolet absorber in the protective layer is preferably 0.01 part by weight to 1 part by weight, and particularly preferably 0.1 part by weight to 0.5 part by weight, based on 1 part by weight of the resin for the protective layer. When the content of the ultraviolet absorber is less than the above range, the light resistance becomes inferior, and when it is more than the above range, the heat-sensitive recording material becomes yellowish and dust is apt to adhere to the thermal head. The content of the fluorescent whitening agent in the thermosensitive coloring layer is preferably 0.05 parts by weight or less, and particularly preferably 0.01 parts by weight or less, relative to 1 part by weight of the leuco dye. The content of the fluorescent whitening agent in the protective layer is preferably 0.05 parts by weight or less, more preferably 0.01 parts by weight or less, relative to 1 part by weight of the resin for the protective layer. When the content of the fluorescent whitening agent is higher than the above, the heat-sensitive recording material tends to be yellowish. The 4,4'-diaminostilbene-2,2'-disulfonic acid derivative which is a fluorescent whitening agent is represented by the following general formula (II).

Embedded image (However, X, Y, Z, and W represent a substituent (including hydrogen).)

The leuco dye in the thermosensitive color developing layer of the present invention may be used alone or in combination of two or more kinds. As such a leuco dye, those applied to the recording material of this kind may be optionally used. For example, triphenylmethane type, fluorane type, phenothiazine type, olamine type,
Leuco compounds of dyes such as spiropyran and indolinophthalide are preferably used. Specific examples of leuco dyes include, for example, 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-
Chlorfluorane, 3-dimethylamino-5,7-dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane,
3-diethylamino-7,8-benzfluorane, 3-
Diethylamino-6-methyl-7-chlorofluorane,
3- (Np-tolyl-N-ethylamino) -5-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- [N- (3'- Trifluoromethylphenyl) amino] -6-diethylaminofluorane, 2- [3,6-bis (diethylamino) -9- (o-chloroanilino) xanthyl] benzoate lactam, 3-diethylamino-6-methyl-7-
(M-Trichloromethylanilino) fluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-di-n-butylamino-7- (o-chloroanilino) fluorane, 3-N-methyl-Nn -Amylamino-6-methyl-7-anilinofluorane, 3-N-
Methyl-N-cyclohexylamino-6-methyl-7-
Anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) fluorane, benzoylleuco methylene 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- (N-ethyl-N-tetrahydrofuran Furyl) amino-6-methyl-
7-anilinofluorane, 3-N-ethyl-N- (2-
(Ethoxypropyl) amino-6-methyl-7-anilinofluorane, 3-N-methyl-N-isobutyl-6-methyl-7-anilinofluorane, 3-morpholino-7-
(N-propyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7-m-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-
7- (N-benzyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluorane, 3-diethylamino-
5-chloro-7- (α-phenylethylamino) fluorane, 3- (N-ethyl-p-toluidino) -7- (α
-Phenylethylamino) fluorane, 3-diethylamino-7- (o-methoxycarbonylphenylamino)
Fluoran, 3-diethylamino-5-methyl-7-
(Α-Phenylethylamino) fluorane, 3-diethylamino-7-piperidinofluorane, 2-chloro-3
-(N-methyltoluidino) -7- (pn-butylanilino) fluorane, 3- (N-methyl-N-isopropylamino) -6-methyl-7-anilinofluorane,
3-di-n-butylamino-6-methyl-7-anilinofluorane, 3,6-bis (dimethylamino) fluorenspyrro (9,3 ')-6'-dimethylaminophthalide, 3- (N -Benzyl-N-cyclohexylamino)
-5,6-benzo-7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-chloro-7
-Anilinofluorane, 3-diethylamino-6-methyl-7-mesitidino-4 ', 5'-benzofluorane,
3-N-methyl-N-isopropyl-6-methyl-7-
Anilinofluorane, 3-N-ethyl-N-isoamyl-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (2 ', 4'-dimethylanilino) fluorane, etc. Can be mentioned.

As the color developer in the heat-sensitive color developing layer of the present invention, various electron-accepting compounds that cause the leuco dye to develop color when heated, or oxidizing agents are used. Such a material is conventionally known, and specific examples thereof include 4,
4'-isopropylidene diphenol, 4,4'-isopropylidene bis (o-methylphenol), 4,4 '
-Secondary-butylidene bisphenol, 4,4'-
Isopropylidene bis (2-tert-butylphenol), zinc p-nitrobenzoate, 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-)
Dimethylbenzyl) isocyanuric acid, 2,2- (3,
4'-dihydroxydiphenyl) propane, bis (4-
Hydroxy-3-methylphenyl) sulfide, 4-
[Β- (p-Methoxyphenoxy) ethoxy] salicylic acid, 1,7-bis (4-hydroxyphenylthio)-
3,5-dioxaheptane, 1,5-bis (4-hydroxyphenylthio) -5-oxapentane, phthalic acid monobenzyl ester monocalcium salt, 4,4'-cyclohexylidene diphenol, 4,4'- Isopropylidene bis (2-chlorophenol), 2,2'-methylene bis (4-methyl-6-tert-butylphenol), 4,4'-butylidene bis (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'-diphenol sulfone, 4-isopropoxy-4'-hydroxydiphenyl sulfone, 4-benzyloxy-4'-hydroxydiphenyl sulfone, 4,4'-diphenol sulfoxide,
Isopropyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate,
1,3-bis (4-hydroxyphenylthio) -propane, N, N'-diphenylthiourea, N, N'-di (m
-Chlorophenyl) thiourea, salicylanilide, methyl bis- (4-hydroxyphenyl) acetate, bis- (4
-Hydroxyphenyl) benzyl acetate, 1,3-bis (4-hydroxycumyl) benzene, 1,4-bis (4
-Hydroxycumyl) benzene, 2,4'-diphenol sulfone, 2,2'-diallyl-4,4'-diphenol sulfone, 3,4-dihydroxyphenyl-4'-
Methyldiphenyl sulfone, 1-acetyloxy-2-
Zinc naphthoate, zinc 2-acetyloxy-1-naphthoate, zinc 2-acetyloxy-3-naphthoate, α,
α-bime (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 can be mentioned.

In the thermosensitive color developing layer of the present invention, various conventional binders can be appropriately used in order to bond and support the leuco dye and the color developer on the support. Specific examples thereof include, for example, as water-soluble polymers, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, starch and its derivatives, methoxy cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, cellulose derivatives such as ethyl cellulose,
Sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester / methacrylic acid terpolymer,
Examples include styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, and the like, and as an aqueous polymer emulsion, a styrene / butadiene copolymer, Latex such as styrene / butadiene / acrylic copolymer, polyvinyl acetate, vinyl acetate / acrylic acid copolymer, styrene / acrylic acid ester copolymer, polyurethane, polyacrylic acid ester, polymethacrylic acid ester, vinyl chloride / Examples thereof include emulsions of vinyl acetate copolymer, ethylene / vinyl acetate copolymer and the like.

In the heat-sensitive color developing layer of the present invention, an auxiliary additive component such as a filler or a heat-fusible agent which is commonly used in heat-sensitive recording materials of this kind may be further added together with the leuco dye and the color developer. It is possible to use together a substance and a surfactant. In this case, as the filler, for example, calcium carbonate, silica, zinc oxide, titanium oxide,
Inorganic fine powders such as aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, surface-treated calcium and silica, as well as organic systems such as urea-formalin resin, styrene / methacrylic acid copolymer, polystyrene resin The fine powder of Examples of heat-fusible substances include higher fatty acids or their esters, amides or metal salts, as well as various waxes, condensates of aromatic carboxylic acids and amines, benzoic acid phenyl esters, higher linear glycols, 3 , 4-epoxy-dialkyl hexahydrophthalate, higher ketone, p-benzylbiphenyl,
Other examples include heat-fusible organic compounds having a melting point of about 50 to 200 ° C.

In order to form the thermosensitive coloring layer in the present invention, a leuco dye, a developer, a binder and the ultraviolet absorber or the fluorescent brightening agent 4,4'-diaminostilbene-2,
Both or either of the 2'-disulfonic acid derivatives, if necessary with auxiliary additives, are dispersed in water to prepare a coating solution for the heat-sensitive color forming layer, which is coated on a support,
It can be dried.

As the organic polymer substance in the protective layer of the present invention, various resins commonly used in the protective layer of this type of heat-sensitive recording material can be used, and examples thereof include polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol and amino group. Modified polyvinyl alcohol, epoxy group-modified polyvinyl alcohol, starch and its derivatives, methoxycellulose, hydroxyethyl cellulose, carboxydimethyl cellulose, methyl cellulose, ethyl cellulose and other cellulose derivatives, polyacrylic acid and its derivatives, styrene / acrylic acid copolymer and its Derivatives, poly (meth) acrylamides and their derivatives, styrene / acrylic acid / acrylamide copolymers, polyethyleneimine, aqueous polyesters, aqueous polyurethanes, isobutylene / maleic anhydride And water-soluble resins such as polymers and derivatives thereof, Boriesuteru, polyurethane, acrylic ester (co) polymer, a styrene / acrylic copolymer,
Epoxy resin, polyvinyl acetate, polyvinylidene chloride,
Examples thereof include polyvinyl chloride and derivatives thereof. It is particularly preferable to use a water-soluble resin in order to improve the plasticizer resistance and oil resistance of the color image.

Further, in order to improve the water resistance of the protective layer, it is particularly preferable to use the water-soluble resin together with a conventional water-proofing agent for making it water resistant. Specific examples of the water-proofing agent include formaldehyde and glyoxal. , Chrome alum, melamine, melamine-formaldehyde resin,
Examples thereof include polyamide resin and polyamide-epichlorohydrin resin. Furthermore, in order to prevent sticking to the thermal head, the protective layer may contain conventional auxiliary additives such as fillers, heat-fusible substances (or lubricants), surfactants, and pressure-color-preventing agents, if necessary. Can be included. Specific examples of the filler and the heat-fusible substance are the same as those exemplified in connection with the thermosensitive coloring layer. The protective layer may be provided in one layer or two or more layers.

To form the protective layer in the present invention, for example, a water-soluble resin, the ultraviolet absorber or the fluorescent brightener 4,4'-diaminostilbene-2,2'-disulfonic acid derivative and / or either One aqueous solution, or a water-proofing agent, a filler, a heat-fusible substance (lubricant), a surfactant, a pressure color-developing inhibitor, etc., is added to prepare a coating solution, which is coated on the thermosensitive color-developing layer. It can be dried.

In the thermosensitive recording material of the present invention, an intermediate layer may be provided between the support and the thermosensitive coloring layer. For the intermediate layer, the materials listed as the materials for the protective layer can be used.

[0017]

EXAMPLES Next, the present invention will be described in more detail by way of examples. The parts and% shown below are based on weight.

Example 1 [Liquid A] 3-di-n-butylamino-6-methyl-7-anilinofluoran 20 parts Polyvinyl alcohol 10% aqueous solution 20 parts Water 60 parts [Liquid B] 4,4'-isopropylidene Dendiphenol 10 parts Polyvinyl alcohol 10% aqueous solution 25 parts Calcium carbonate 15 parts Water 50 parts [C liquid] 2- (2-hydroxy-3-t-butyl-5-methylphenyl) -5-chlorobenzotriazole [Compound (I )] 20 parts Polyvinyl alcohol 10% aqueous solution 20 parts Water 60 parts Disperse a mixture having the above composition using a sand mill so that the average particle diameter is 2 μm or less [Liquid A],
[B liquid] and [C liquid] were prepared. Next, the above [liquid A],
[Solution B], [Solution C] and 1 of 4,4′-diaminostilbene-2,2′-disulfonic acid derivative which is a fluorescent whitening agent
% Aqueous solution (Brand name = BLANKOPHOR Z-PSG
/ Bayer Japan Co., Ltd.), respectively 1: 8:
The coating liquid for the thermosensitive color forming layer was prepared by mixing and stirring so that the ratio became 1: 0.4. Next, the coating liquid is applied onto a high-quality paper having a basis weight of 50 g / m ^{2 so} that the dry weight is 7 g / m ² ,
It was dried to form a thermosensitive coloring layer. [Solution D] Polyvinyl alcohol 10% aqueous solution 63 parts Polyamide epichlorohydrin (solid content 25%) 10 parts Silica 3 parts Zinc stearate 1 part Water 23 parts Further, the above [Solution D] has a dry weight of 5 on the thermosensitive coloring layer.
The heat-sensitive recording material of the present invention was obtained by applying the coating solution so that the coating amount was g / m ² and drying it to provide a protective layer, and then subjecting it to calendering at a pressure of 35 kg / cm ² .

Example 2 The same procedure as in Example 1 was carried out except that, in Example 1, [D solution] was replaced with [E solution] below, and no optical brightener was added when the coating solution for the thermosensitive color developing layer was prepared. A heat-sensitive recording material of the present invention was obtained. [Solution E] Polyvinyl alcohol 10% aqueous solution 63 parts Polyamide epichlorohydrin (solid content 25%) 10 parts BLANKOPHOR Z-PSG (solid content 1%) 13 parts Silica 3 parts Zinc stearate 1 part Water 10 parts

Example 3 A thermosensitive recording material of the present invention was obtained in the same manner as in Example 2 except that the [F liquid] was replaced with the [E liquid]. [F liquid] Polyvinyl alcohol 10% aqueous solution 63 parts Polyamide epichlorohydrin (solid content 25%) 10 parts BLANKOPHOR Z-PSG (solid content 1%) 3 parts Silica 3 parts Zinc stearate 1 part Water 20 parts

Example 4 In Example 1, a coating solution for a thermosensitive color forming layer was prepared without using [C liquid] and a fluorescent whitening agent, and [D liquid] was added to the following [G].
Liquid solution] was obtained in the same manner as in Example 1 to obtain a heat-sensitive recording material of the present invention. [G liquid] 10% aqueous solution of polyvinyl alcohol 63 parts Polyamide epichlorohydrin (solid content 25%) 10 parts BLANKOPHOR Z-PSG (solid content 1%) 13 parts [C liquid] (ultraviolet absorber dispersion liquid) 10 parts silica 3 parts stearin Zinc acidate 1 part

Example 5 The same as Example 1 except that the coating solution for the thermosensitive color developing layer was prepared without using the [C liquid] and the [D liquid] was replaced with the following [H liquid]. The thermosensitive recording material of the present invention was obtained. [H liquid] Polyvinyl alcohol 10% aqueous solution 63 parts Polyamide epichlorohydrin (solid content 25%) 10 parts [C liquid] (ultraviolet absorber dispersion liquid) 10 parts Silica 3 parts Zinc stearate 1 part Water 13 parts

Example 6 The present invention was carried out in the same manner as in Example 1 except that the mixing ratio of the coating liquid of Example 1 was changed from 1: 8: 1: 0.4 to 1: 8: 1: 0.2. A thermosensitive recording material was obtained.

Example 7 [Liquid A] [Liquid B] [Liquid C] of Example 1, BLANKOP
HOR Z-PSG and zinc stearate,
The coating liquid for the heat-sensitive color forming layer was prepared by mixing and stirring so as to be 1: 8: 1: 0.4: 0.1. Next, the coating liquid was applied to a high-quality paper having a basis weight of 50 g / m ^{2 so} that the dry weight was 7 g / m ^2, and dried to form a thermosensitive coloring layer. Then, calendering was performed at a pressure of 20 kg / cm ² to obtain a heat-sensitive recording material of the present invention.

Comparative Example 1 A heat-sensitive recording material of Comparative Example 1 was obtained in the same manner as in Example 2 except that [Equipment E] was changed to [Equipment D].

Comparative Example 2 A thermosensitive recording material of Comparative Example 2 was obtained in the same manner as in Example 4, except that the above [Solution H] was used instead of [Solution G].

Comparative Example 3 The heat sensitivity of Comparative Example 3 was the same as in Example 4 except that the compound (I) was changed to 2,4-dihydroxybenzophenone in [C solution] in [G solution] of Example 4. A recording material was obtained.

Comparative Example 4 In the [C liquid] of the [G liquid] of Example 4, the compound (I) was replaced with 2- (2'-hydroxy-5'-methylphenyl) -benzotriazole. A thermal recording material of Comparative Example 4 was obtained in the same manner as in Example 4.

Each of the heat-sensitive recording materials obtained as described above was tested for light resistance, coating liquid stability and the like. The results are shown in Tables 1 and 2. The test was conducted as follows. (1) Light resistance test 0.35 W / m ² (340 mm) using a xenon weatherometer ATLAS Ci35A (manufactured by Toyo Seiki Co., Ltd.)
Irradiate for 15 hours under the following conditions to determine the background density of Macbeth RD
It measured with the blue filter of -914. The background density before the test was also measured with a Macbeth RD-914 blue filter. (2) Stability of coating liquid After coating, the coating liquid was left at room temperature (20 ° C) for 1 day with stirring. The state of the liquid was visually observed and evaluated as follows. ×: Vigorous thickening and liquid separation are observed. △: Thickening and separation were slightly observed. ○: Thickened but no separation. ◎ …… Neither thickening nor separation was observed at all.

[0030]

[Table 1]

[0031]

[Table 2]

As described above, the heat-sensitive recording material of the present invention has a higher degree of whiteness of the background than the heat-sensitive recording materials of the comparative examples and is excellent in light resistance without causing coloration of the background due to light. It is a material and has excellent stability of the coating liquid.

[0033]

The heat-sensitive recording material of the present invention is a heat-sensitive recording material having a high degree of whiteness of the background and excellent light resistance without causing the background to be colored by light. According to the method for producing a thermosensitive recording material of the present invention, the stability of the coating liquid for forming the thermosensitive coloring layer or the protective layer is excellent, and uniform coating of the thermosensitive coloring layer or the protective layer can be performed.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuji Miyamoto 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (7)

[Claims] 1. A heat-sensitive recording material having a leuco dye and a heat-sensitive color-developing layer mainly composed of a color developer capable of coloring the dye when the heat-sensitive color-developing layer is represented by the following structural formula (1). A heat-sensitive recording material containing an ultraviolet absorber and a fluorescent whitening agent comprising a 4,4'-diaminostilbene-2,2'-disulfonic acid derivative. Embedded image 2. A thermosensitive coloring layer mainly composed of a leuco dye and a color developer capable of coloring the dye on a support, and a protective layer mainly composed of an organic polymer substance formed in the thermosensitive coloring layer. A heat-sensitive recording material having a heat-sensitive color forming layer or a protective layer, and an ultraviolet absorber represented by the following structural formula (1):
A heat-sensitive recording material containing a fluorescent whitening agent comprising a 4'-diaminostilbene-2,2'-disulfonic acid derivative. Embedded image 3. A thermosensitive coloring layer mainly composed of a leuco dye and a color developing agent for coloring the dye on a support, and a protection mainly composed of an organic polymer substance formed on the thermosensitive coloring layer. In a thermal recording material having a layer, the following structural formula (1)
One of the ultraviolet absorber and the fluorescent whitening agent consisting of 4,4'-diaminostilbene-2,2'-disulfonic acid derivative represented by the above is contained in the thermosensitive coloring layer, and the other is contained in the protective layer. Heat sensitive recording material Embedded image 4. The heat-sensitive recording material according to claim 1, wherein the content of the fluorescent whitening agent in the heat-sensitive color developing layer is 0.01 part by weight or less relative to 1 part by weight of the leuco dye. . 5. The heat-sensitive recording material according to claim 2, wherein the content of the fluorescent whitening agent in the protective layer is 0.01 part by weight or less with respect to 1 part by weight of the resin for the protective layer. 6. A method for producing a heat-sensitive recording material comprising a support, a leuco dye, and an aqueous dispersion containing a developer and a binder for coloring the dye when the dye is heated and dried to form a heat-sensitive coloring layer. In the method, the aqueous dispersion contains an ultraviolet absorber represented by the following structural formula (1) and 4,4'-diaminostilbene-
A method for producing a heat-sensitive recording material, which comprises a fluorescent whitening agent comprising a 2,2'-disulfonic acid derivative. Embedded image 7. A thermosensitive color forming layer is formed by coating and drying an aqueous dispersion containing a leuco dye and a color developing agent and a binder that cause the dye to develop a color when heated on a support. In a method for producing a heat-sensitive recording material in which a solution containing a substance as a main component is applied and dried to form a protective layer, an aqueous dispersion containing a leuco dye, a developer and a binder, or an organic polymer substance as a main component The solution is a UV absorber represented by the following structural formula (1) and 4,4′-diaminostilbene-2,2 ′.
-A method for producing a heat-sensitive recording material, characterized in that it contains both or one of a fluorescent whitening agent composed of a disulfonic acid derivative. Embedded image