JPH0632054A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a heat-sensitive recording material having a favorable long term keeping quality of a color development image, by a method wherein a heat-sensitive recording layer containing a dicarboxylic acid derivative having leuco dye, a developer and two aliphatic carboxylic groups are provided on a substrate. CONSTITUTION:After fixed quantities each of leuco dye, a developer which develops a color by contacting with the dye and a dicarboxylic acid derivative having two dicarboxylic groups to be represented by a formula I (A shows a 1 to 8C alkylene group and vinylene group, R1 and R2 show a hydrogen atom or an alkyl group or a cycloalkyl group or hydroxl group or a halogen atom are pulverized and agitated along with a binder such as water-soluble fat, they are mixed up with each other and a coating liquid for a heat sensitive recording layer is prepared. This heat-sensitive recording coating is applied onto a substrate such as a plastic film or paper, dried, the heat sensitive recording layer is laminated and heat sensitive recording material is obtained. The heat-sensitive recording layer may be either a single layer or multiple layer and an over layer or an under layer or a back layer can be laminated when necessity arises.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material having good image stability.

[0002]

2. Description of the Related Art Generally, a heat-sensitive recording material is mainly composed of a color-forming system comprising a colorless or light-colored color-forming dye as a color-forming agent on a support such as paper, synthetic paper, plastic film and a color-developing agent which makes the color develop when heated. A thermosensitive coloring layer as a component is provided, and a colored image can be obtained by heating with a hot pen, a thermal head, a laser beam, a strobe lamp, or the like. Compared with other recording materials, this recording material does not require complicated processing such as development and fixing, and recording can be obtained in a short time with a relatively simple device, noise generation and environmental pollution are small, and cost is low. It is used for copying books, documents, etc. due to its low price, electronic calculator, facsimile, ticket vending machine,
It is useful as various recording materials such as label printers and recorders.

Color-forming dyes used in heat-sensitive recording materials include, for example, colorless or light-colored leuco dyes having a lactone, lactam or spiropyran ring, and conventional developers include organic acids and phenolic substances. ing. The recording material using the color former and the developer is widely used because of its high image density and high whiteness of the background.

However, such a leuco dye-based color image has poor storability and it is difficult to store a printed image as it is for a long period of time. Further, there is a defect that the image is easily erased by touching oils and fats such as fingerprints and mechanical fats.

In order to improve the long-term storability of such a leuco dye-based color image, for example, JP-A-60-187584 is used.
Proposes a method of incorporating a hindered amine and a hindered phenol as an image stabilizer in the heat-sensitive recording layer. Further, JP-A-59-194890 proposes to use a salicylic acid derivative or a metal salt thereof and a hydroxybenzoic acid derivative as a color developer.

Further, in order to improve image stability against oils and fats, in JP-A-57-6795, a metal salt of an aliphatic carboxylic acid or a metal salt of an aromatic carboxylic acid is used alone or together with a phenolic compound as a developer. Proposed to be used. Further, in JP-A-59-185693, it is proposed to use a polyvalent metal salt of an aliphatic organic acid and an aromatic carboxylic acid as a color developer. However, it is difficult to say that any of these methods have sufficient image storability and stability, and at present, they are not practical.

[0007]

SUMMARY OF THE INVENTION The present invention is intended to provide a heat-sensitive recording material excellent in long-term storage stability of a color image and stability against oils and fats.

[0008]

According to the present invention, there is provided a heat-sensitive recording material comprising a support and a heat-sensitive recording layer comprising a leuco dye and a color developer which develops a color when the leuco dye is brought into contact, as a main component. Provided is a heat-sensitive recording material characterized in that the heat-sensitive recording layer contains at least one selected from dicarboxylic acid derivatives represented by the following general formula.

General Formula HOOC-A-COOH In the formula, A is a divalent group which may have a substituent and may contain an ether bond or an unsaturated bond hetero atom.

Specific examples of the compound of the above general formula used in the present invention include those shown in Table 1 below, but the present invention is not limited thereto.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

The leuco dye used in the present invention is
These leuco dyes may be applied singly or in a mixture of two or more, and as such leuco dyes, those applied to the recording material of this type may be arbitrarily applied, for example, triphenylmethanephthalide type and triallylmethane type. , Fluorane, phenothiazine, thioferolane, xanthene, indophthalyl, spiropyran, azaphthalide, chromenopyrazole, methine, rhodamineanilinolactam, rhodaminelactam, quinazoline, diazaxanthene, Leuco compounds such as bislactones are preferably used. Examples of such compounds include those shown below. 3,3-bis (p-dimethylaminophenyl) -phthalide 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide 3,3-bis (p-dimethylaminophenyl) -6-diethylaminophthali De 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide 3,3-bis (p-dibutylaminophenyl) phthalide 3-cyclohexylamino-6-chlorofluorane 3-dimethylamino-5,7-dimethyl Fluoran 3- (N-methyl-N-isoamylamino) -6-methyl-7-anilinofluorane 3- (N-methyl-N-isobutylamino) -6-methyl-7-anilinofluorane 3- (Np-tolyl-N-ethylamino) -6-methyl-7-anilinofluorane 3- (N-methyl-N-amylamino) -6-methyl-
7-anilinofluorane 3- (N-methyl-N-cyclohexylamino) -6-
Methyl-7-anilinofluorane 3- (N-methyl-N-iso-propylamino) -6
-Methyl-7-anilinofluorane 3- (N-methyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane 3-diethylamino-7,8-benzfluorane 3-diethylamino-7 -Chlorofluorane 3-diethylamino-7-methylfluorane 3-diethylamino-6-methyl-7-chlorofluorane 3-pyrrolidino-6-methyl-7-anilinofluorane 3-diethylamino-6-methyl-7- (M-Trichloroanilino) fluorane 3-diethylamino-7- (o-chloroanilino) fluorane 3-dibutylamino-7- (o-chloroanilino) fluorane 3-diethylamino-6-methyl-7-anilinofluorane 3-dibutyl Amino-6-methyl-7-anilinofluorane 3-diethylamino- - methyl-7- (2 ', 4'-
Dimethylanilino) fluorane 3- (N, N-diethylamino) -5-methyl-7-
(N, N-Dibenzylamino) fluorane benzoyl leuco methylene blue 6'-chloro-8'-methoxybenzoindolinospiropyran 6'-bromo-8'-methoxybenzoindolinospiropyran 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-propyltrifluoromethylanilino) fluorane 3-pyrrolidino-7-trifluoromethylanilinofluorane 3-diethylamino-5-chloro-7- (N-benzyl-tri Fluoromethylanilino) fluorane 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluorane 3-diethylamino-5-chloro-7- (α-phenylethylamino) fluorane 3- (N-ethyl-N- p-toluidino) -7- (α-
Phenylethylamino) fluorane 3-diethylamino-7- (o-methoxycarbonylphenylethyl) fluorane 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluorane 3-diethylamino-7-piperidinoaminofluorane 2-chloro-3- (N-methyltoluidino) -7- (p
-N-butylanilino) fluorane 3,6-bis (dimethylamino) fluorene spiro (9,3 ')-6'-dimethylaminophthalide 3- (N-ethyl-N-cyclohexylamino) -5
6-benzo-7-α-naphthylamino-4′-bromofluorane 3-diethylamino-6-chloro-7-anilinofluorane 3- (N-ethyl-N-2-ethoxypropylamino)
-6-Methyl-7-anilinofluorane 3- (N-ethyl-N-tetrafurfurylamino) -6
-Methyl-7-anilinofluorane 3-diethylamino-6-methyl-7-mesitidino-
4 ', 5'-benzofluorane 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-dichloro4,7-dibromophthalide bis (p-dimethylaminostyryl ) -1-Naphthalenesulfonylmethane bis (p-dimethylaminostyryl) -1-p-tolylsulfonylmethane and the like.

In the present invention, various electron-accepting compounds such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof can be used as the color developer. The specific examples thereof include, but are not limited to, those shown below.

4,4'-isopropylidenediphenol 4,4'-isopropylidene bis-o-methylphenol 4,4'-sec-butylidene bisphenol 4,4'-isopropylidene bis (2-tert-butylphenol) Zinc p-nitrobenzoate 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzylisocyanuric acid 2,2- (3,4′-dihydroxyphenyl) 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) -3-oxapentane phthalic acid monobenzyl ester monocalcium salt 4,4′-cyclohexylidenediphenol 4,4′-isopropylidenebis (2-chlorophenol ) 2,2′-Methylenebis (4-methyl-6-tert-)
Butylphenol) 4,4'-butylidene bis (6-tert-butyl-2)
-Methylphenol) 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'-diphenol sulfoxide p-Hydroxybenzoate isopropyl p-Hydroxybenzoate benzyl protocatechuate benzyl stearyl gallate Stearyl gallate lauryl gallate Octyl 1,3-bis (4-hydroxyphenylthio) -propane N , N'-diphenylthiourea N, N'-di (m-chlorophenyl) thiourea salicylanilide bis- (4-hydroxyphenyl) acetic acid methyl bis (4-hydroxyphenyl) acetic acid benzyl 1,3-bis (4-hydroxy) Phenyl ) Benzene 1,4-bis (4-hydroxyphenyl) benzene 2,4′-diphenol sulfone 2,2′-diallyl-4,4′-hydroxyphenyl sulfone 3,4-dihydroxy-4′-methyldiphenyl sulfone 1 -Zinc acetyloxy-2-naphthoate 2-Acetyloxy-3-zincnaphthoate Zinc 2-acetyloxy-1-naphthoate 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.

To produce the heat-sensitive recording material of the present invention, a leuco dye, a color developer, the compound of the present invention and other auxiliaries may be supported and bound on a support. As the binder in this case, various conventional binders can be used in appropriate amounts, and specific examples thereof include the following.

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, styrene /
Maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein and other water-soluble polymers, as well as polyvinyl acetate, polyurethane, polyacrylic ester, poly Methacrylic acid ester, vinyl chloride / vinyl acetate copolymer, ethylene / vinyl acetate copolymer emulsion, styrene / butadiene / acrylic copolymer latex and the like.

In the present invention, various heat-fusible substances can be used as the sensitivity improver, and specific examples thereof include the followings, but the present invention is 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, Greacol Carbonate, Dibenzyl 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-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) biphenyl, p-aryloxybiphenyl, p -Propargyloxybiphenyl, dibenzoyloxymethane, dibenzoyloxypropane, dibenzyl disulfide,
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.

In the case of obtaining a heat-sensitive recording material according to the present invention, a leuco dye, a color developer, and the compound of the present invention are optionally added together with an additive component which is commonly used in this kind of heat-sensitive recording material.
For example, a filler, a surfactant, a lubricant, a pressure color-developing inhibitor, etc. 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, inorganic fine powder such as surface-treated calcium or silica, and urea. -Formalin resins, styrene / methacrylic acid copolymers, polystyrene resins, vinylidene chloride resins, and other organic fine powders can be mentioned.

Regarding the layer structure, it may be a single layer or a multilayer, and an over layer, an under layer and a back layer may be provided if necessary.

[0022]

EXAMPLES The present invention will now be described in more detail with reference to Examples. The parts and% shown below are based on weight.

Examples 1 to 5 and Comparative Examples 1 to 3 The following mixtures were pulverized in a magnetic ball mill for 2 days to prepare [solution A], [solution B], [solution C] and [solution D]. .

[Liquid A] 3- (N, N-Dinormalbutylamino) -6-methyl-7-anilinofluorane 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 60 parts [liquid B] 4,4′- Isopropylidenediphenol 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [C liquid] Compound having image stabilizing action shown in Table 2 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [D liquid] Carbonate Calcium 20 parts 5% aqueous solution of methyl cellulose 20 parts Water 60 parts Next, [solution A] 10 parts, [solution B] 30 parts, [solution C] 30
Part, [D liquid] 30 parts, and 10 parts of a 20% aqueous solution of an isobutylene / maleic anhydride copolymer are mixed to prepare a thermosensitive color forming layer-forming liquid, which is dried on a wood free paper having a basis weight of 50 g / m ² . A thermosensitive recording material is prepared by coating and drying the coating so that the amount of dye deposited is 0.5 g / m ^2, and then calendering the layer surface so that the surface smoothness is 500 to 600 seconds. Was produced.

The heat-sensitive recording material obtained as described above was heated at a temperature of 150 using a thermal gradient tester manufactured by Toyo Seiki Seisakusho.
Printing was performed under the conditions of ° C and a pressure of 2 kg / cm ^{2 for} 1 second, and the image density and background density were measured with a Macbeth densitometer RD-914 (filter: W-106), and the value was taken as the density before the test.

Next, the samples after printing were tested for storability and oil resistance as follows. The results are shown in Table 4.

Storability: Print sample at a temperature of 40 ° C.
The density of the image area was measured after storage under a humidity condition of 90% and a temperature of 60 ° C. for 48 hours.

Oil resistance: Cotton seed oil was applied to the printed part, and the density of the image part was measured after the product was stored under a drying condition at a temperature of 40 ° C. for 16 hours.

The concentration after each of the above storage tests was also measured by a Macbeth densitometer RD-914 (filter: W-106).

[0030]

[Table 4]

It can be seen from Table 4 that the heat-sensitive recording material of the present invention is excellent in storability and oil resistance in the image area and hardly causes image fading.

[0032]

As described above, the heat-sensitive recording material of the present invention in which the dicarboxylic acid derivative represented by the above general formula is contained in the heat-sensitive color forming layer of the present invention has extremely high stability in the image area and is practical. It is expensive.

Claims (2)

[Claims] 1. A heat-sensitive recording material having a heat-sensitive recording layer comprising, on a support, a leuco dye and a color developer which develops a color when the leuco dye is brought into contact with a main component, wherein the heat-sensitive recording layer further has the following general formula: A heat-sensitive recording material containing a dicarboxylic acid derivative having two aliphatic carboxyl groups represented by: General formula: However, in the above general formula, A: an alkylene group having 1 to 8 carbon atoms (which may be through a hetero atom such as an oxygen atom or a sulfur atom, a benzene ring or a carbonyl group) and a vinylene group are shown. R ₁ and R ₂ : hydrogen atom, alkyl group, cycloalkyl group,
A hydroxyl group, a halogen atom, a phenyl group, a benzoyl group and an aralkyl group are shown. 2. The heat-sensitive recording material according to claim 1, wherein the dicarboxylic acid derivative having two aliphatic carboxyl groups represented by the general formula is one of the following compounds. [Chemical 2]