JPH01114484A - heat sensitive recording material - Google Patents

Abstract

PURPOSE:To improve stability of an image, by a method wherein a thermal color-developing layer containing leuco dye and a catechol complex salt as a color developing agent which allows the leuco dye to form color on contact is provided on a substrate to form a thermal recording material. CONSTITUTION:A coating liquor is prepared by dissolving, dispersing a leuco dye, catechol complex salt of a color developer to allow the leuco dye to form color on contact in a solvent or water. The coating liquor is applied and dried on a substrate such as paper for lamination of a thermal color-developing layer, and thus a thermal recording material is formed. The catechol complex salt to be used as a color developer is represented by formula I (wherein Me represents an n-valent metal ion, m is a number obtained by reducing n from the coordination number of Me, R represents H, a metal ion or a colorless mono- or multi-dentate ligand which forms a complex through a hetero atom), as metal ions Na, K, Mg, Ca, Ba ions may be mentioned.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording material, and particularly to a heat-sensitive recording material with good image stability.

[Prior art]

Heat-sensitive recording materials are generally heat-sensitive recording materials that are coated on a support such as paper, synthetic paper, or plastic film, and have a color-forming system that is mainly composed of a colorless or light-colored dye as a coloring agent and a color developer that causes the dye to develop a specific color under heat. It has layers, and a colored image can be obtained by heating it with a thermal pen, thermal head, laser beam, strobe lamp, etc. Compared to other recording materials, this recording material does not require complicated processing such as development and fixing.
Records can be obtained in a short time using a relatively simple device.

Due to its advantages such as low noise generation, low environmental pollution, and low cost, it is used for copying books, documents, etc., and is also useful as a variety of recording materials for computers, facsimiles, ticket vending machines, labels, recorders, etc. be.

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 organic acids, phenolic substances, and the like have been conventionally used as color developers. Recording materials using color formers and color developers are widely used because of their high image density and whiteness of the background, but as the demand for heat-sensitive recording methods has increased in recent years, the quality of heat-sensitive recording materials has improved. In particular, in fields where the reliability of recorded images is important, it is essential for thermal recording materials to provide images that are highly stable against plasticizers contained in oils, fats, and plastics. It is a condition.

Conventionally, in order to improve the stability of recorded images, for example, a thermosensitive coloring layer containing a large amount of water-resistant and chemical-resistant resin, a thermosensitive coloring layer containing a resin that hardens with heat or light, or a resin protective layer on the surface. However, there are problems in that the process becomes complicated and the cost increases, and the thermal responsiveness decreases.

On the other hand, as proposals for improving image stability by improving color developers,
No. 59-96991, No. 60-13852, etc., methods using derivatives of bisphenol S, JP-A-58
-160191, a method using trisphenols, and JP-A-57-6795, JP-A-61-47292.
There are methods using carboxylic acid metal salts etc. in Japanese Patent Publications, etc.
It is difficult to say that any of these methods is sufficient in terms of image stability and the like.

〔the purpose〕

An object of the present invention is to provide a heat-sensitive recording material with excellent stability of colored images.

〔composition〕

According to the present invention, there is provided a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer that causes the leuco dye to develop color upon contact, characterized in that a catechol complex salt is used as the color developer. Recording materials will be provided.

Since the heat-sensitive recording material of the present invention uses a catechol complex salt as a color developer, it has excellent image stability without decoloring of colored images due to plasticizers, cottonseed oil, etc.

In the present invention, the catechol complex salt used as a color developer is a metal complex salt represented by the following formula, and these compounds may be used alone or in a mixture of two or more kinds.

In the formula, Me is an n-valent metal ion, n is a number obtained by subtracting n from the coordination number of Me, and R is a colorless metal ion that can form a complex through a hydrogen atom, a metal ion, or a petro atom. is a monodentate or polydentate ligand.

Specific examples of metal ions in the catechol metal complex used in the present invention include sodium, potassium, magnesium, calcium, barium, aluminum, silicon, tin, zinc, and zirconium.

In addition, as a ligand, various nitrogen-containing organic compounds such as
Examples include aliphatic amines having 1 to 18 carbon atoms, pyridines, picolines, imidazoles, benzimidazoles, and anilines, and particularly preferred examples include pyridine, imidazole, 1-methylimidazole, and 2-methylimidazole. , 2-phenylimidazole, N-vinylimidazole, 2-methylindole, 2-phenylindole, benzimidazole, 1,2-dimethylimidazole, antipyrine, isopropylantipyrine, bromoantipyrine, aniline, quinoline, and the like.

The leuco dyes used in the present invention may be applied singly or in a mixture of two or more types. As such leuco dyes, those applied to this type of heat-sensitive material can be arbitrarily applied. For example, triphenyl Methane type, fluoran type, phenothiazine type, auramine type, spiropyran type,
Leuco compounds of dyes such as indolinophthalide are preferably used. Specific examples of such leuco dyes include 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-dibutylaminophenyl, 3.3-bis(p-dimethylaminophenyl)-6-chlorophthalide.

3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3
-N-methyl-N-isobutyl-6-methyl-7-anilifluorane, 3-N-ethyl-N-isoamyl-6-methyl-7-anilinofluorane, 3-diethylamino-7-chlorofluoran.

3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-(N-p-tolyl-N-ditylamino) -6-Methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2-(N-(3'-trifluoromethylphenyl)
amino)-6-dinithylaminofluorane, 2-(3
, 6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid 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-
Anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane.

3-diethylamino-6-methyl-7-(2',4'-
dimethylanilino)fluoran, 3-(N,N-diethylamino)-5-methyl-7-(
N,N-dibenzylamino)fluorane, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrylosvirane, 3-(2 '-Hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phthalide, 3-(2'-hydroxy-4'-diethylaminof"
enyl)-3-(2'-methoxy-5'-nitrophenyl) phthalide, 3-(2'-hydroxy-4'-diethylaminophenyl)-3-(2'-methoxy-57-methylphenyl) phthalide, 3-(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-5'
-methylphenyl)phthalide, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane.

3-diethylamino-5-chloro-7-(N-benzyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluorane, 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)fluorane, 3-diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(p-n
-butylanilino)fluoran, 3-(N-methyl-N-isopropylamino)-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran.

3.6-bis(dimethylamino)fluorene spiro(9
゜3')-6'-dimethylaminophthalide, 3-(N
-benzyl-N-cyclohexylamino)-5,6-penzo7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-N-ethyl-N -(2-ethoxypropyl)amino-6-methyl-7-anilinofluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-
6-methyl-7-anilite fluorane, 3-diethylamino-6-methyl-7-mesitidino 4',5'-benzofluoran, and the like.

In addition, in the present invention, the color developer represented by the above-mentioned ``-tsuri'' is used, but if necessary, other color developers can be used in combination.In this case, the color developer used in combination includes the leuco dye. Various electron-accepting compounds that develop color when contacted, such as phenolic compounds, thiophenolic compounds, and thiourea derivatives.

Organic acids and metal salts thereof are preferably used, and specific examples thereof include those shown below.

4.4'-isopropylidene bisphenol, 4.4
′ -isopropylidene bis(0-methylphenol)
, 4.4'-Secondary-butylidene bisphenol 4.4'-Isopropylidene bis(2-tert-
butylphenol).

4.4'-cyclohexylidene diphenol, 4.4
′ -isopropylidene bis(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, Gallic octyl.

1,7-bis(4-hydroxyphenylthio)-3,5
-Dioxahebutane, 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, etc.

In order to produce the heat-sensitive recording material of the present invention, a leuco dye, a color developer, and auxiliary components may be bonded and supported on a support.
As the binder in this case, various commonly used binders can be appropriately used, and specific examples thereof include the following.

Polyvinyl alcohol, starch and its derivatives, hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, cellulose derivatives such as ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide/acrylic ester copolymer, acrylamide/acrylic ester/methacrylic In addition to water-soluble polymers such as acid ternary copolymers, styrene/maleic anhydride copolymer alkali salts, isobutylene/maleic anhydride copolymer alkali salts, polyacrylamide, sodium alginate, gelatin, and casein, polyvinyl acetate , polyurethane, polyacrylic acid, polyacrylic ester.

Emulsions such as vinyl chloride/vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer, and styrene/butadiene copolymer.

Latex such as styrene/butadiene/acrylic copolymer.

Further, in the present invention, if necessary, auxiliary additive components 1 commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, thermofusible substances (or lubricants), etc., can be used in combination. In this case, fillers include 1, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated inorganic fine powders such as calcium and silica. , urea-formalin resin, styrene/methacrylic acid copolymer, polystyrene resin, and other organic fine powders. Examples of thermofusible substances include fatty acids such as stearic acid and behenic acid, fatty acid amides such as stearic acid amide and palmitic acid amide, zinc stearate, aluminum stearate, calcium stearate, zinc palmitate, and behenic acid. Fatty acid metal salts such as zinc acid, p-benzylbiphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, β-naphthoic acid phenyl ester, phenyl 1-hydroxy-2-naphthoic acid ester, l-hydroxy-2-naphthoic acid methyl ester, diphenyl carbonate, terephthalic acid dibenzyl ester, terephthalic acid dimethyl ester, 1,4
-dimethoxynaphthalene, 1,4-jethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 1,2-bis(phenoxy)ethane, 1,2-bis(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, 1,3-bis(
2-vinyloxyethoxy)benzene, l,4-bis(
2-vinyloxyethoxy)benzene, p-(2-vinyloxyethoxy)biphenyl, p-aryloxybiphenyl, p-propargyloxybiphenyl, dibenzoyloxymethane, 1,3-dibenzoyloxypropane, dibenzyl disulfide, 1.1-diphenylethanol, 1.1-diphenylpropatol, p-(benzyloxy)benzyl alcohol, 1<3>-diphenoxy-2-propatol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene.

Examples include N-octadecylcarbamoylbenzene.

〔effect〕

The heat-sensitive recording material of the present invention using the catechol complex salt as a color developer has extremely high stability in the image area and is highly practical.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples. Note that all parts and percentages shown below are based on weight.

Examples 1 to 3 and Comparative Examples The following mixtures were each ground in a magnetic ball mill for two days to prepare [Liquid A], [Liquid CB] and [Liquid C].

[Liquid A]

10% aqueous solution of polyvinyl alcohol 20 parts water
60 parts [Liquid B] Color developer in Table 1 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water
60
Part [Liquid C] Calcium carbonate 20 parts Methyl cellulose Part Aqueous solution 20 parts Water
60 parts Next, 10 parts of [Liquid A], 30 parts of [Liquid B], 30 parts of [Liquid C], and 10 parts of a 20% alkaline aqueous solution of isobutylene/maleic anhydride copolymer were mixed to form a thermosensitive coloring layer forming liquid. .

This was coated on high-quality paper with a basis weight of 50 g/rrr so that the dye adhesion amount after drying was 0.5 g/m, and dried to form a heat-sensitive coloring layer. A heat-sensitive recording material was prepared by calendering the surface of the layer so as to obtain the following properties.

Regarding the heat-sensitive recording material obtained as described above.

Temperature 150℃ using Toyo Seiki Seisakusho thermal gradient tester
The image density and background density were measured using a Macbeth densitometer R-914 (filter: V-106).

Next, the printed sample was tested for plasticizer resistance and oil resistance. In these tests, a plasticizer (DOA) and cottonseed oil were applied to the sample, and the density of the image area after -8 was measured.

The above results are shown in Table-1.

Note) The phase and R of the color developer in Table 1 each represent the same meaning as in the general formula in the specification.

From the above, it can be seen that the heat-sensitive recording material of the present invention is extremely superior in that there is no browning caused by plasticizers or oil in the image area.6 Patent Applicant Rico Co., Ltd. -

Claims (1)

[Claims] (1) A heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer that causes the leuco dye to develop color upon contact, characterized in that a catechol complex salt is used as the color developer.